identifier: Charron, Rémi  (2007) Development of a genetic algorithm optimisation tool for the early stage design of low and net-zero energy solar homes.  PhD thesis, Concordia University.

abstract: Homes that utilise solar thermal and solar photovoltaic (PV) technologies to generate as much energy as they consume in a year are referred to as net-Zero Energy Solar Homes (ZESH). This thesis presents the methodology used to develop a Genetic Algorithm (GA) Optimisation Tool that finds optimal configurations of low and net-zero energy solar homes taking into consideration effects from the use of different technologies, local climate, economics, and other factors. The tool links a low energy solar home model developed in TRNSYS with a GA optimisation program that automates the search for cost-effective building designs. The tool varies a predefined set of parameters including building width to length ratio, heating system type, solar thermal collector type and size, and more.  The results from the TRNSYS model are compared with monitored data of an energy efficient house to verify that the model was correctly implemented. A total of 40 test cases were evaluated with the tool in order to verify the effects of climate, energy consumption target, control strategy, utility price structures, and other factors, to examine their impact on the resulting optimal design configurations. The GA program was capable of finding designs that were on average within 0.5% of the best known solution with the evaluation of only 0.00012% of the solution space. Results indicated that homes could be built with near equivalent monthly costs of conventional homes, while reducing the annual net-energy consumption by an order of magnitude. A reduction in PV system costs or the introduction of appropriate feed-in-tariffs had significant impacts on the overall cost-effectiveness of ZESH.  The thesis clearly demonstrated the extent to which local climate, economic factors, and specific design constraints can have a major impact on the optimal design configuration, which limits the usefulness of generic design guidelines. The methodology developed was also a novel way of using TRNSYS for the optimisation of whole building design through the use in updated input and parameter files. The development of building design optimisation tools will lead to various applications ranging from policy development work where the benefits of different incentive mechanisms are quantified, to design assistance, and building code development work.


identifier: Oblin, George  (2007) The Paix des Braves agreement of 2002 : an analysis of Cree responses.  PhD thesis, Concordia University.

type: Thesis NonPeerReviewed

abstract: The original contribution of this thesis is the juxtaposition of postmodernist notions with Cree societal issues, an approach that offers a new perspective on contemporary Cree reality and opens up a broader discursive space within which to consider the challenges the Cree are facing. This case study of Cree responses to the Paix des Braves Agreement of 2002 provides material evidence for a qualitative, contextual, genealogical analysis of existing social and communicative practices, including discursive practice, competing ideologies and organisation and power. Various social practices constitute what is conceptualised as communication. In order to understand communication from this perspective, it is important to focus on such practices. There are communicative aspects to matters of social organisation, leadership and decision-making, and values and ethics. Since all these practices have been undergoing rapid change for the Cree of northern Quebec, especially in the last few decades, the people are struggling to position themselves within this new reality and find a way to articulate it. The Agreement considered in this thesis is one reached between the government of Quebec and the political leadership of the Cree of James Bay, northern Quebec on major developmental issues. Its touted benefits were recognition of Cree interests over all the Cree territory and economic benefits totalling approximately $3.5 billion for the fifty-year duration of the Agreement. Opposition to the Agreement was based on perceived lack of consultation, haste and secrecy in signing, and probably foremost, the sense some had that their leaders had sacrificed the land for economic gain. The purpose of this thesis is not to favour any discourse on the issues pertaining to the Paix des Braves but to attempt to understand the conditions of their emergence. These conditions include a long-held tradition of decision-making through consensus, on the one hand, and external pressures from governments and industries to align Cree modes of governance and functioning with mainstream ones, on the other. Cree responses have been mixed and often based on totalising and essentialist notions, such as with regard to what it means to be Cree or pertaining to progress and development. Employing a genealogical approach implies accounting for social practices and meanings without conceptualising the subject in a transcendental or essentialist way. It also entails tracing how norms that are often assumed and taken for granted within a particular social context are linked to regulative rationality. By focusing on the social construction of such notions it is hoped that a better understanding will result and that possibilities of action for the Cree will emerge.


identifier: Qasaimeh, Mohammad Ameen Yousef  (2007) Polyvinylidene fluoride - based MEMS tactile sensor for minimally invasive surgery.  Masters thesis, Concordia University.

abstract: Minimally invasive surgery (MIS) procedures have been growing rapidly for the past couple of decades. In MIS operations, endoscopic tools are inserted through a small incision on human's body. Although these procedures have many advantages such as fast recovery time, minimum damage to human body and reduced post operative complications, it does not provide any tactile feedback to the surgeon.  This thesis reports on design, finite element analysis, fabrication and testing of a micromachined piezoelectric endoscopic tactile sensor. Similar to the commercial endoscopic graspers, the sensor is teeth like in order to grasp slippery tissues. It consists of three layers; the first layer is a silicon layer of teeth shapes on the top and two supports at the bottom forming a thin plate and a U-Channel. The second layer is a patterned Polyvinylidene Fluoride (PVDF) film, and the third layer is a supporting Plexiglas. The patterned PVDF film was placed on the middle between the other two layers. When a concentric load is applied to the sensor, the magnitude and the position of the applied load are obtained from the outputs of the sensing elements which are sandwiched between the silicon supports and the Plexiglas. In addition, when a soft object/tissue is place on the sensor and load is applied the degree of the softness/compliance of the object is obtained from the outputs from the middle PVDF sensing elements, which are glued to the back of the thin silicon plate. The outputs are related to the deformation of the silicon plate which related to the contacting object softness.  The sensor has high sensitivity and high dynamic range as a result it can potentially detect a small dynamic load such as a pulse load as well as a high load such as a firm grasping of a tissue by an endoscopic grasper. The entire surface of the tactile sensor is also active, which is an advantage in detecting the precise position of the applied point load on the grasper. The finite element analysis and experimental results are in close agreement with each other. The sensor can potentially be integrated with the gasper of a commercially available endoscopic grasper


identifier: Rababah, Mahmoud  (2007) Damage tolerance analysis using the eXtended finite element method.  Masters thesis, Concordia University.

abstract: While the regular Finite Element Method (FEM) is well developed and robust, it is not particularly well suited to model evolving discontinuities, since the construction of a discontinuous space requires the element topology to be aligned with the geometry of the discontinuity. This in turn requires regeneration of the mesh as the discontinuity evolves, resulting in projection errors and a significant computational cost.  The eXtended Finite Element Method (XFEM) is a new technique which was developed recently to account for the evolving discontinuities in the crack growth problems. In XFEM, special functions (discontinuous and near tip functions) are added to the regular FEM to model the discontinuities without regenerating the mesh. Using this property in XFEM, and assuming Linear Elastic Fracture Mechanics (LEFM) concept, the damage tolerance analysis to determine the time or the number of loading cycles required for a smaller pre-existent crack to grow to critical size can be accomplished more efficiently than that in the regular FEM.  The derived XFEM-formulation has been effectively implemented and in-house computer code has been developed to find the stress intensity factors and to model the crack growth efficiently without re-meshing the structure. Numerous benchmark 2-D problems with cracks located at different locations and inclined in different angles have been investigated and the results are validated with those available in the literature.  Finally, the potential application of XFEM in damage tolerance analysis has been demonstrated.


identifier: Vukov, Tamara  (2007) Affective politics, effective borders : news media events and the governmental formation of Canadian immigration policy.  PhD thesis, Concordia University.

abstract: In the wake of the widespread media focus on the securitization of Canadian immigration policy and its harmonization in a North American "smart border" regime, this thesis examines the role that large-scale news media events around immigration and refugee asylum play in the formation of Canadian immigration policy. Two crucial news events in particular, the 1999 landings of Fujian Chinese migrants off the coast of British Columbia, and the focus on the ostensibly porous Canadian border following the September 2001 attacks in the United States, are analyzed in terms of their impacts on the introduction and intensification of trafficking and security policies, as well as selection, interdiction and enforcement (deportation/detention) practices. This project draws on and reworks theories of biopolitics and governmentality, along with the emerging literature on affect in cultural studies, to consider the effects that spectacular news events around migration have on the governmental formation of immigration policies. Methodologically, it draws on elements of interpretive and discourse analysis, qualitative interviews, along with an approach developed to account for the affective dimensions of news events in everyday life. The thesis argues that these highly affective news media events have been crucial to the formation of an increasingly racialized and sexualized biopolitics of migration focused on the preventative targeting of "risky" migrant bodies and their precarious movements and labour, as crystallized in the recent Immigration and Refugee Protection Act (2002) and the Safe Third Country Agreement (2004)


identifier: Sanyal, Joydip  (2007) Dynamic response of geared shaft systems with time-dependent boundary conditions subjected to static transmission error.  Masters thesis, Concordia University.

abstract: A rotating gear pair experiences high vibration and noise mainly due to tooth profile error, mounting error, tooth wear, friction backlash and periodic change of meshing stiffness. The combined effect of the manufacturing error, mounting error and elastic tooth deformation is considered as the static transmission error that introduces internal displacement excitation within the gear pair. Such internal excitation generates torsional vibration through the driving and driven shafts even in absence of external excitations. Thus the vibration problem of a geared system involves homogeneous equations of motion with time dependent boundary conditions. The present research is to investigate the torsional vibrations of a geared system by developing a continuous model that converts the homogeneous equations with non-homogeneous boundary conditions into non-homogeneous equations with homogeneous boundary conditions. The influence of friction, tooth wear, backlash and other nonlinear variables have been ignored in the formulation.  The free vibration results of the proposed model are validated by developing the classical Rayleigh-Ritz model with Bhat's boundary characteristic orthogonal polynomial functions. The results are also validated by performing experiments in the laboratory for a simple geared system. Torsional vibration responses are determined in both time and frequency domains. In addition to the proposed continuous model the discrete model is simulated to determine torsional vibrations and dynamic torque generated due to static tooth error.  The experimental investigations are carried out by measuring free torsional vibrations with strain gauge and frequency analysis by a spectrum analyzer


identifier: Uzzal, Md. Rajib Ul Alam  (2007) Role of railway vehicle-track system and design parameters on flat-induced impact load.  Masters thesis, Concordia University.


identifier: Zhang, Hongda  (2007) Optimal cutter size determination for finish pocketing of NURBS profile parts.  Masters thesis, Concordia University.


identifier: Zhao, Tianbo  (2007) An approach to feed rate determination for high-speed machining of 2-D NURBS profiles.  Masters thesis, Concordia University.

abstract: High-speed machining is a new trend in the manufacturing industry, especially in the mould and aerospace industries. Compared to conventional CNC machining techniques, high-speed machining has two obvious advantages: high feed rates and high part accuracy, which requires some new requirements on machining parameters. One requirement is on the material removal rate (MRR). In non-high speed machining, the MRR is not necessary to be kept constant. However, a constant MRR is a basic requisite in high-speed machining (HSM) processes, because the tool load is very sensitive to the MRR in high-speed machining. Quick tool wear, unexpected breakage, and deflection of tool occur frequently if the MRR is higher. Generally, the mould and aerospace industries have many parts including free surface or complex curves represented by NURBS (Non-Uniform Rational B-Splines). In this work, research is conducted to ensure the MRR be constant in machining 2-D NURBS curve profiles. Another peculiarity of the high-speeding machining is that its toolpath must be smooth without sharp direction changes. Overcut or gouging may occur for momentum of the tool is too big in this machining. If there are many sharp connections in linear toolpath, the feed rate cannot reach to the specified high value, because of frequent starts and stops of the servomotor, shortening the motor life. In this research, effective NURBS toolpaths are generated to machine complex curve profiles, like NURBS or B-Spline contours.  In this thesis, an intelligent approach to determining the machining parameters for NURBS profiles is established. First, a 2-D geometric model of machining NURBS profiles is given. Second, a cutting force model is established based on the artificial neural-network. Third, appropriate feed rates are gotten from the predicted cutting force of machining. Then new NURBS segments are proposed to represent the previous curve in the specified tolerance. Finally, simulation and NC programs are given to demonstrate the advantages of this research


identifier: Yang, Zhiyong  (2007) The impact of parenting on susceptibility to peer influence : role of self-concept and culture.  PhD thesis, Concordia University.

abstract: The influence from peers is viewed as the most important factor that causes substance use among teenagers (e.g., Akers et al. 1979; Kandel 1996). Among a variety of preventive factors, certain aspects of parenting (e.g., parental responsiveness, psychological control) are believed to affect adolescents' susceptibility to negative peer influence. These studies have produced some intriguing findings. Nonetheless, three significant gaps remain in the literature. First, previous research of parent-peer linkages has exclusively focused on deviance behaviors. We know little about how parental practices may affect adolescents' susceptibility to peer influence (SPI) on consumer choices. Second, past studies have mainly examined the direct effects of parenting on negative peer pressure, while the process by which parents affect peer relationships remains an area that to date has been underexplored. Lastly, interpersonal influence is inherently a cultural process. Despite the importance of culture as a contextual factor, there has been little academic research on the topic of SPI in a cross-cultural setting.  The purpose of this research is to fill these gaps by further explicating parental influences on SPI. Different from previous studies, we will examine parent-peer linkages not only from the angle of negative peer pressure, but also from a more general perspective to study peer influence on purchasing patterns. More importantly, we will investigate not only the direct effects of relevant parent practices on SPI per se, but also the mediated effects of parenting on SPI through the adolescent self-concept. In addition, we will extend the proposed parent-self-peer paradigm developed in Western cultures to Eastern cultures, in order to investigate the moderating role of culture on the proposed relationships among parenting dimensions, key elements of self, and SPI.  In Study 1, triadic data from 109 English-Canadian families was collected to verify the proposed parent-self-peer model in the Western context. Consistent with our expectations, results revealed that the effects of parental responsiveness on SPI were fully mediated by key aspects of self-concept, including interdependent self-construal, self-esteem, and self-monitoring. Since Study 1 was cross-sectional and could not verify the causality proposed in our framework, we conducted Study 2 to determine the causal directions of the parent-self-peer relationships through a longitudinal analysis of the National Longitudinal Survey of Children and Youth (NLSCY) data. Findings of the longitudinal analysis largely supported our assumption that parenting dimensions are more likely to be the antecedents of peer influence than conversely.  In Study 3, we gathered 1,142 sets of family triadic data from mainland China and selected a part of the sample (n = 216) to test the hypothesized moderating effects of culture on the parent-self-peer linkages. Cross-cultural similarities as well as differences were found in this study. Specifically, in both cultures, parental responsiveness tended to be negatively associated with SPI, while psychological control tended to be positively associated with it. The magnitudes of these relationships and the way through which parents affect SPI, however, were different across the English-Canadian and the Chinese samples. These findings are broadly supportive of our hypotheses. Theoretical and managerial implications to the literature will also be discussed.


identifier: Mohsni, Sana  (2008) Earnings, idiosyncratic volatility and costs of capital.  PhD thesis, Concordia University.

abstract: This thesis consists of three essays. The first essay (chapter two) examines short- and long-term persistence and predictability of earnings and cash-flow growth rates. Aggregate results show that the mean firm exhibits persistence in short-term earnings growth rates, but little persistence in growth at the long-run. More consistent with economic intuition, aggregate cash-earnings growth rates show some short-term mean-reversion and little persistence in the long-run. Consistent with the earnings smoothing theory, cross-sectional results show short-term persistence in earnings growth rates. Cash-earnings, which suffer less manipulation than accrual earnings, show short-term cross-sectional mean-reversion. Long-term growth rates show evidence of mean-reversion in both cases. Our most interesting findings are related to various examined attributes such as age, industry characteristics, listing exchange, and the number of analysts following the stock which are shown to have an impact on the growth persistence of individual firms.  The second essay (chapter three) examines the increasing trend in idiosyncratic volatility of stock returns, which has been documented by Campbell et al. (2001). Using the Campbell (1991) return decomposition framework, we relate idiosyncratic volatility of returns to the volatility of changes in expected ROEs for one-, two- and three-year horizon forecasts (i.e., to the volatility of cash-flow news). The upward trend in idiosyncratic volatility documented by Campbell et al. (2001) is associated with a similar increasing trend in the volatilities of cash-flow news for the three forecast horizons. This relationship is persistent after correcting for analysts' forecast biases and is consistent for newly-listed and mature firms and for earnings (non-) announcement periods. Our findings support an informational explanation to the increasing trend in idiosyncratic volatility, and are consistent with the market efficiency hypothesis which implies that stock return volatility is caused by an increase in the uncertainty of fundamental variables.  In the third essay (chapter four) we estimate the internal rates of return (IRR) for domestic and cross-listed Canadian firms, nine GICS sectors, and cap-based portfolios. Using the Fama and French (1999) methodology, we distinguish between the IRR on value or the cost of capital as expected by stakeholders and the IRR on cost that represents the implied real cost of investments. The real cost of capital [equity] over the period 1960-2003 is 5.90 [6.58] percent for the entire nonfinancial sector. The real return on such cost is 6.64 [7.78] percent indicating that, similar to the U.S., the Canadian corporate sector creates value. As expected, cross-listed firms enjoy, on average, lower costs of capital and equity than domestic firms. Although the cost of capital varies considerably across GICS sectors, value is created almost equally by all GICS sectors. IRR values on cap-based portfolios are consistent with the negative relationship between costs of capital and firm size. While both types of IRRs decrease on average after we correct for replacement costs and include extraordinary items, the IRR on cost remains higher than the IRR on value confirming the positive value creation hypothesis. Allowing for inflation illusion, our findings suggest that equity was undervalued during most of the sample period and that the misvaluation was lower for cross-listed firms


identifier: Shi, Ning Yaqi  (2007) Cross listing, management earning forecasts, and firm values.  PhD thesis, Concordia University.

abstract: This dissertation investigates the incentives for and consequences of management earnings forecasts released by foreign firms opting into the U.S. markets. It also attempts to measure how country-level governance mechanisms (e.g., legal institutions and the SEC enforcement) and firm-level governance mechanisms (e.g., ownership and auditor) interact to influence the answers. It is the earliest study to link management earnings forecasts, corporate governance and firm valuation in an international setting. Additionally, by investigating issues on voluntary information that cross-listed firms sequentially provide, this dissertation extends the Investor Recognition Hypothesis by Merton (1987), and adds to our understanding about reputational bonding mechanisms (Coffee, 1999; Siegel, 2005).  Essay I provides a primer on the institutional background of cross-listed firms, and demonstrates that these firms are unique in regulatory, economic and legal schemes. Specifically, foreign firms listing in the U.S. are characterized by various home-country legal institutional environments, different listing statuses (ADR Level I, II, III, and direct listing), active global product market interactions and different firm-level concentrated ownerships. These distinctive aspects of cross-listed firms make my study relevant to the literature on management earnings forecasts as well as firm valuation.  Essay 2 focuses on the incentives to provide management earnings forecasts released by foreign firms listing in the U.S. I document that legal institutions, as measured by legal origin, investor protection and judicial efficiency, are positively associated with the likelihood of forecast occurrence. In addition, cross-listed firms are more apt to release forecast disclosures when they list on major U.S. stock exchanges, and have a higher proportion of foreign sales. Further, I indicate that the likelihood of forecasts is positively associated with institutional ownership, but negatively associated with the proportion of cash flow rights controlled by the largest shareholders.  Essay 3 explores how management earnings forecasts, other firm attributes, and country institutional factors interact with each other to affect firm values. I find that forecasting cross-listed firms enjoy higher valuation premiums relative to non-forecasting firms. I also provide evidence that cross-listed firms from weaker legal institutions benefit more from disclosing management earnings forecasts. Moreover, I demonstrate that forecast precision and forecast frequency are favorably associated with firm valuation. Overall, this essay suggests that cross-listed firms are rewarded for their voluntary bonding to transparent financial reporting practices.  Key words. Crass Listing, Firm Values, International Governance Convergence, Legal Regimes, Management Earnings Forecasts, Reputational Bonding.


identifier: Ding, Yu  (2008) Tableau-based reasoning for description logics with inverse roles and number restrictions.  PhD thesis, Concordia University.

abstract: The tableaux algorithm is a general technique for deciding concept satisfiability problems in description logics (DLs). It is useful not only for practical implementations, but also for studying the correctness and complexity of concrete decision procedures.  There is a family of DLs that currently lack appropriate optimization techniques. The research focuses on these DLs which typically have inverse roles and number restrictions (corresponding to ontology languages OWL-lite and OWL-DL respectively). We provide solutions to known problems such as the unsoundness of global tableaux caching, and present new tableau-based algorithms for concept satisfiability problems in these DLs. The research presented in this thesis is significant in several aspects. Firstly, based on an equivalence discovered during the course of the research, we are able to show an elimination of inverse roles for a sub-family of DLs. Our experiments have confirmed the practicality of this technique. Secondly, we provide three sub-tableaux caching techniques that are sound and global (but with different power in caching functionality). Finally, we present two ExpTime tableau-based decision procedures, with the one for [Special characters omitted.] achieving an improved worst-case upper bound in the strong sense of binary coding of numbers (based on the integer linear programming technique)


identifier: Hassine, Jameleddine  (2008) Formal semantics and verification of use case maps.  PhD thesis, Concordia University.

abstract: Common to most software development processes is that system functionalities are defined early in the life cycle in terms of informal requirements and visual models. As requirement descriptions evolve, they quickly become error-prone and difficult to understand leading to prolonged detrimental effects on reliability, cost, and safety of a software system that are very costly to fix in later phases of the software development process. Thus, the development of techniques and tools to support requirement specification development, understanding, validation, verification, maintenance and reuse becomes an important issue.  This thesis proposes a novel methodology named Early Stages V&V (Early Stages Validation & Verification), which combines the semi-formal scenario-based Use Case Maps language with formal techniques to help comprehend, validate and verify requirements. UCM models allow the description of functional requirements and high-level designs at early stages of the development process. Use Case Maps is being standardized as part of the User Requirements Notation (URN), the most recent addition to ITU-Ts family of languages. In the first part of the thesis, we propose a concise and rigorous formal semantics for Use Case Maps based on Abstract State Machines (ASM) formalism. The resulting semantics are embedded in an ASM-UCM simulation engine and are expressed in AsmL, an advanced ASM-based executable specification language, which is used to validate UCM models through simulation.  Timing issues are often overlooked during the initial system design and treated as separate behavioral issues and therefore described in separate models. In the second part of the thesis, we extend the Use Case Maps language to cover timing constraints. A potential timed version of UCM (called Timed UCM ) is formalized using Clocked Transition Systems (CTS) and Timed Automata (TA). The proposed semantics can be applied to comprehend, analyze, validate and verify (using model checking) timed UCM models. In addition, we have proposed a novel UCM-based property pattern system that combines qualitative, real-time and architectural properties into single graphical representation. The resulting pattern system is mapped to popular temporal logics CTL, TCTL and ArTCTL (Architectural real-time temporal logic), which is an extension to TCTL introduced in this research that provides temporal logics with architectural scopes.  In order to achieve an efficient validation and verification of UCM models and to assess the impact of a specification change (e.g. as a result of a bug fixing or a feature upgrade), we extend the application of the well-known technique of program slicing to Use Case Maps language.  An ongoing example of a simple telephone system is used to illustrate these concepts. The thesis validates the Early Stage V&V methodology by implementing it and applying it to two case studies: IP Multicast Protocol and an Online Store application.


identifier: Rahman, Md Mahmudur  (2008) Semantical representation and retrieval of natural photographs and medical images using concept and context-based feature spaces.  PhD thesis, Concordia University.

abstract: The growth of image content production and distribution over the world has exploded in recent years. This creates a compelling need for developing innovative tools for managing and retrieving images for many applications, such as digital libraries, web image search engines, medical decision support systems, and so on. Until now, content-based image retrieval (CBIR) addresses the problem of finding images by automatically extracting low-level visual features, such as odor, texture, shape, etc. with limited success. The main limitation is due to the large semantic gap that currently exists between the high-level semantic concepts that users naturally associate with images and the low-level visual features that the system is relying upon. Research for the retrieval of images by semantic contents is still in its infancy. A successful solution to bridge or at least narrow the semantic gap requires the investigation of techniques from multiple fields. In addition, specialized retrieval solutions need to emerge, each of which should focus on certain types of image domains, users search requirements and applications objectivity.  This work is motivated by a multi-disciplinary research effort and focuses on semantic-based image search from a domain perspective with an emphasis on natural photography and biomedical image databases. More precisely, we propose novel image representation and retrieval methods by transforming low-level feature spaces into concept-based feature spaces using statistical learning techniques. To this end, we perform supervised classification for modeling of semantic concepts and unsupervised clustering for constructing codebook of visual concepts to represent images in higher levels of abstraction for effective retrieval. Generalizing upon vector space model of Information Retrieval, we also investigate automatic query expansion techniques from a new perspective to reduce concept mismatch problem by analyzing their correlations information at both local and global levels in a collection. In addition, to perform retrieval in a complete semantic level, we propose an adaptive fusion-based retrieval technique in content and context-based feature spaces based on relevance feedback information from users. We developed a prototype image retrieval system as a part of the CINDI (Concordia INdexing and DIscovery system) digital library project, to perform exhaustive experimental evaluations and show the effectiveness of our retrieval approaches in both narrow and broad domains of application.


identifier: Yao, Shengji  (2007) Experimental approaches for understanding conceptual design activities.  PhD thesis, Concordia University.

abstract: Designers play an important and critical role in developing innovative product design, which is the key for a company to survive in the highly competitive market with ever-increasing demands from customers. However, how designers think, reason, judge, and make decisions has not yet been studied well. This thesis aims to develop experimental approaches to qualitatively and quantitatively understand designers' cognitive activities in order to explore product innovation in the early design stages.  To study designers' cognitive activities, a new protocol analysis method is developed. In the protocol analysis experiment, designers' activities were recorded when solving a design problem. Designers were interviewed to recall their design process immediately after finishing the design. Then, the recorded verbal data were analyzed by transcribing, segmentation and encoding for further analysis. In general, protocol analysis is used to transform the unstructured data collected from designers into structured data. Existing protocol analysis methods used to study designers' cognitive activities heavily depend on specific design problems, specific domains and the persons who analyze the protocol data. The new protocol analysis method presented in this thesis is based on the concept of the state of design and recursive object model. It can be easily applied to any design problem and any domain. Using this method, the changes of designers' cognitive activities during the design process can be quantified. Some guidelines and recommendations for assisting designers to deliver an innovative design are summarized at the end of the present thesis based on the experimental results. The protocol analysis results have also been used to evaluate Environment-Based Design (EBD) as a descriptive design model; hence, EBD can be used as the theoretical foundation to illustrate, describe, and explain how designers conduct a design task.  Another part of my thesis is to simulate the design process by developing a virtual experiment. In the virtual experiment, the selected design problem: finite element mesh design, can be automatically solved using a program developed in the computer environment of Visual C++. Net 2003. Then, different settings of the parameters, different strategies, different formulations of design requirements, and different sequences for solving the design problem are simulated to compare the differences of meshes. Three routes leading designers to innovative designs are proposed and examined through this virtual experiment. Based on the three routes, an ANN-based element extraction method for finite element mesh design is developed to illustrate the feasibility of the three routes for changing design solutions.  Therefore, the two experimental approaches proposed in this thesis can be used for understanding design activities in a more systematic manner


identifier: Yan, Guorong  (2008) Liquid slosh and its influence on braking and roll responses of partly filled tank vehicles.  PhD thesis, Concordia University.

abstract: Liquid cargo contained in a partly-filled tank is known to experience the sloshing movement when subjected to manoeuvre-induced disturbances. Large amplitude slosh can be induced within a partly-filled road tank vehicle under mild to severe directional manoeuvres, which could severely degrade the vehicle stability and directional control limits. A three-dimensional computational fluid dynamics slosh model is implemented for the partly-filled cleanbore and baffled tanks on the basis of the Navier-Stokes equations incorporating the VOF technique. A comprehensive experimental study is conducted to analyze the fluid slosh within a scale model tank with and without the baffles under continuous as well as single-cycle sinusoidal lateral and longitudinal acceleration excitations. The three-dimensional fluid slosh responses are further investigated for full scale baffled and unbaffled vehicle tanks using the validated fluid slosh model. The fluid slosh characteristics are analyzed under different fill volumes corresponding to a constant load and subjected to excitations representing steady-turning, straight-line braking, braking-in-turn and path change maneuvers. The fluid slosh analyses are also carried out to explore the anti-slosh effectiveness of baffles and to evaluate the effects of baffle design factors, such as equalizer and the orifice size.  The influences of transient fluid slosh on the tank vehicle stability and responses are studied by incorporating the fluid slosh model to in-plane vehicle models. The two-dimensional roll-plane slosh models of partly-filled tanks of different cross-sections are integrated with the roll moment equilibrium of an articulated vehicle to derive the vehicle roll stability limits. The roll stability analyses are performed for circular and "Reuleaux triangular" tanks under the conditions of constant and variable cargo loads. The results attained are compared with the quasi-static solutions to demonstrate the role of transient slosh loads on the roll stability limits. The three-dimensional slosh model of a partly-filled tank is also integrated into a 7-DOF pitch plane model of a tridem truck to analyze its straight-line braking characteristics in the presence of fluid slosh. The straight-line braking responses of the coupled tank-vehicle model with and without baffles are analyzed under different fill volumes but constant load for different magnitudes of braking treadle pressure and road surface adhesion limits


identifier: Samadi, Behzad  (2008) Stability analysis and controller synthesis for a class of piecewise smooth systems.  PhD thesis, Concordia University.

abstract: This thesis deals with the analysis and synthesis of piecewise smooth (PWS) systems. In general, PWS systems are nonsmooth systems, which means their vector fields are discontinuous functions of the state vector. Dynamic behavior of nonsmooth systems is richer than smooth systems. For example, there are phenomena such as sliding modes that occur only in nonsmooth systems. In this thesis, a Lyapunov stability theorem is proved to provide the theoretical framework for the stability analysis of PWS systems. Piecewise affine (PWA) and piecewise polynomial (PWP) systems are then introduced as important subclasses of PWS systems.  The objective of this thesis is to propose efficient computational controller synthesis methods for PWA and PWP systems. Three synthesis methods are presented in this thesis. The first method extends linear controllers for uncertain nonlinear systems to PWA controllers. The result is a PWA controller that maintains the performance of the linear controller while extending its region of convergence. However, the synthesis problem for the first method is formulated as a set of bilinear matrix inequalities (BMIs), which are not easy to solve. Two controller synthesis methods are then presented to formulate PWA and PWP controller synthesis as convex problems, which are numerically tractable. Finally, to address practical implementation issues, a time-delay approach to stability analysis of sampled-data PWA systems is presented. The proposed method calculates the maximum sampling time for a sampled-data PWA system consisting of a continuous-time plant and a discrete-time emulation of a continuous-time PWA state feedback controller.


identifier: Cao, Dongpu  (2008) Theoretical analyses of roll- and pitch-coupled hydro-pneumatic strut suspensions.  PhD thesis, Concordia University.

abstract: Vehicle suspension design and dynamics analysis play a key role in enhancement of automotive system performance. Despite extensive developments in actively-controlled suspensions, their commercial applications have been limited due to the associated high cost and weight. Alternative designs in either passive or semi-active suspensions are highly desirable to achieve competitive vehicle performance with relatively lower cost and greater reliability. This dissertation research proposes two hydro-pneumatic suspension strut designs, including a twin-gas-chamber strut, and systematically investigates various concepts in roll- and pitch-coupled suspensions employing hydraulic, pneumatic and hybrid fluidic interconnections between the wheel struts. The proposed strut designs, including single- and twin-gas-chamber struts, offer larger working area and thus lower operating pressure, and integrate damping valves. Nonlinear mathematical models of the strut forces due to various interconnected and unconnected suspension configurations are formulated incorporating fluid compressibility, floating piston dynamics, and variable symmetric and asymmetric damping valves, which clearly show the feedback damping effects of the interconnections between different wheel struts.  The properties and dynamic responses of the proposed concepts in roll- and pitch-coupled suspension struts are evaluated in conjunction with in-plane and three-dimensional nonlinear vehicle models. The validity of the vehicle models is demonstrated by comparing their responses with the available measured data. The analyses of the proposed coupled suspensions are performed to derive their bounce-mode, anti-roll, anti-pitch and warp-mode properties, and vehicle dynamic responses to external excitations. These include road roughness, steering and braking, and crosswinds. The results suggest that the fluidically-coupled passive suspension could yield considerable benefits in enhancing vehicle ride and handing performance. Furthermore these offer superior design flexibility.  The suspension struts offer a large number of coupling possibilities in the three-dimensions, some of which however would not be feasible, particularly for commercial vehicles where suspension loads may vary considerably. A generalized analytical model for a range of interconnected suspensions is thus developed, and a performance criterion is formulated to assess the feasibility of a particular interconnection in a highly efficient manner. The handling and directional responses of a three-dimensional vehicle model employing X-coupled hydro-pneumatic suspension are evaluated under split-o straight-line braking and braking-in-a-turn maneuvers. The results clearly show that the X-coupled suspension offers enhanced anti-roll and anti-pitch properties while retaining the soft vertical ride and warp properties. Fundamental pitch and vertical dynamics of a road vehicle are also considered to derive a set of essential design rules for suspension design and tuning for realizing desirable pitch performance


identifier: Taraboulsi, Choucri-Gabriel  (2008) Development, implementation and testing of an expert system for detection of defects in gas turbine engines.  PhD thesis, Concordia University.

abstract: Unbalance and misalignment are the major causes of vibration in rotating machinery, yet only limited research has been conducted on misalignment. The literature reports that misalignment results in an increase in the vibration at a frequency corresponding to two times the rotating speed (2x responses). The research on misalignment conducted so far has modeled the rotor as two coupled shafts supported on linear and non linear bearings, while misalignment is at the coupler. The results reported to date are inconsistent and the vibration response of a misaligned rotor system is not clearly understood. This dissertation presents a study on the effects of a single shaft misalignment on the dynamic response of a rotor-shaft system. A rotor system supported on two rigid bearings with unbalance and misalignment is modeled using the energy method, and Lagrange formulation is used to establish the equations of motion. The misalignment is modeled through introduction of pre-load and nonlinear shaft stiffness in the direction of pre-load. The model is validated by comparing the natural frequencies predicted using the simulation to the rotor system eigenvalue and the forced response from the simulation is verified using finite element method. A response due to perfectly aligned case is compared with those for parallel and angular misalignments of various magnitudes. Simulations are carried out for a speed range of 0 to 10,000 rpm, and the response of the rotor at the 2x is carefully examined to establish the effects of various misalignment and non-linear parameters on the response. Experiments are conducted using a rig test to compare with analytically predicted trends. Various gas turbine engine data gathered from the field are also used to confirm the vibration pattern predicted by the simulations. The simulated results are finally used to develop an expert system that can identify unbalance and misalignment in a rotor system. The expert system is developed using Neural Network. Two types of Neural Networks are explored, the back-propagation and the Logicon Projection Network. Finally, both networks are modified, trained and tested using simulation data. The Logicon projection network showed superior performance during training, and was chosen over the back-propagation network. The developed expert system is tested using field test data of gas turbine engines to demonstrate its effectiveness.


identifier: Cai, Zhi Yong  (2008) Parameterization methods for dynamic design of gas turbine engine control systems.  Masters thesis, Concordia University.


identifier: Etezad-Borojerdi, Mohammad  (2007) Geotechnical performance of group of stone columns.  PhD thesis, Concordia University.

abstract: Stone columns are known to be a cost effective and environmental friendly ground improvement technique, which is widely used to enhance the performance of shallow foundations built on soft ground. Stone columns increase bearing capacity, reduce settlement, reduce significantly the consolidation period and minimize the liquefaction potential of the ground.  The current design of these columns is generally based on theories developed for single columns, ignoring the group interaction and accordingly the group efficiency. In the literature, reports can be found to confirm that the failure of single stone column is mostly due to bulging, meantime for a group of stone columns, the failure mechanism takes place by massive shear failure of the group and the surrounding soils.  The objective of this thesis is to develop a numerical model, based on a two dimensional finite element technique. The model is capable to identify the different mode of failures of single and group of stone columns for a given columns/soil/loading condition. In these cases, group interactions were examined and evaluated. Parametric study was conducted on the parameters believed to govern this behavior. The results produced in this study showed that ground reinforced by group of stone columns may fail by general, local or punching shear failure, depending on geometry of the group and properties of the surrounding soils.  Analytical models were developed for the ultimate bearing capacity of single and groups of stone columns. The models take into consideration the column interaction among the group and the strength of the surrounding soils and accordingly depict the appropriate mode of failure. Furthermore, analytical model was developed for the prediction of settlement of foundations under single or widely spaced stone columns. The design theories are provided with design procedures and charts for practical use.


identifier: Fu, Chunyan  (2008) Signaling for conferencing in mobile ad hoc networks.  PhD thesis, Concordia University.

abstract: Mobile Ad hoc NETworks (MANETs) are networks that do not need to be pre-configured. They are composed of transient nodes connected through wireless interfaces. Due to their flexibility, the ease to build and the associated low cost, they are gaining more and more momentum. They are also seen as part of the fourth generation wireless networks. New applications, such as conferencing, are emerging for such networks. Conferencing enables a set of applications such as audio/video conferencing, debating, distance-learning and multi-party gaming. The implementation of conferencing in MANETs is not an easy task due to scarce network resources, heterogeneous devices, frequently changing topology and unstable wireless connections. It challenges each technical aspect of conferencing: signaling, media handling and conference control. Signaling is the control component of conferencing. It handles the session initiation, modification and termination.  In this work, we focus on signaling for conferencing in MANETs. Two types of MANETs are considered: standalone MANETs and integrated MANETs/3G networks. Background information is provided, requirements are derived and the state of the art, including signaling protocols such as SIP and H.323, are reviewed. Since there is no existing solution that meets all of the derived requirements, we propose a novel cluster-based signaling architecture that meets the requirements of signaling for standalone MANETs. The clusters are application-layer clusters that are dynamically created and deleted for a conference. We also propose a signaling architectures for integrated MANETs/3G networks. The solution is based on conference gateways. We implement the architectures using SIP extensions. Experimental results are obtained from prototypes and OPNET based simulations. In the prototype, we built the signaling system on a small scale network using IEEE 802.11 ad hoc settings. In the OPNET simulation, we use MANET features. From experiments, we found that clustering is a very promising approach for solving signaling problems in MANETs. Being aware of several performance issues of our signaling systems, we further propose optimization schemes that are based on cross-layer design. We also implement some of these schemes and apply them to our signaling systems. The evaluation shows that the schemes significantly improve the signaling performance.


identifier: Moghaddas, Mahsa  (2008) Finite element analysis and passive vibration control of the Timoshenko beam traversed by a moving vehicle using an optimized tuned mass damper.  Masters thesis, Concordia University.

abstract: In the present work, the behavior of a combined bridge-vehicle system in which, the bridge is modeled as a Timoshenko beam and the vehicle is considered as a half car model has been investigated using the finite element method. Responses of the beam and the vehicle model have been obtained and then validated with those reported in literature. The limitation of considering the vehicle as a quarter car model and also the effect of taking into account the rotatory inertia and shear deformation i.e. using the Timoshenko beam model has also been investigated.  The finite element formulation of the Timoshenko with the attached Tuned Mass Dampers (TMDs) has been derived. Then the general equation of motion of a Timoshenko beam element with the attached TMDs traversed by a moving half car model has been obtained by the combination of two previously derived finite element equations of motion; for the beam with attached TMDs and the beam under the moving vehicle.  Finally, a design optimization algorithm has been developed in which the derived finite element analysis module has been combined with the optimization procedure. The algorithm is based on the Sequential Programming Technique (SQP), to determine the optimum values of the parameters (frequency and damping ratios) of one TMD, for minimization of the maximum frequency response of the beam midspan under the moving vehicle.  The obtained results show that by adding an optimally tuned mass damper to the system a significant faster damping can be achieved


identifier: Mizouni, Rabeb  (2008) Formal composition of partial system behaviors.  PhD thesis, Concordia University.

abstract: Modeling the behavior of a system under development has shown to be a very effective way to ensure that it will have better chance to be constructed correctly. With the growing complexity of systems, building this model has become a major task that requires a significant time investment and a high level of expertise. Incremental approaches that help construct a system model from partial behavioral descriptions have been widely adopted. The challenge in such approaches lies in finding both the adequate behavioral formalism that fits the needs of the analyst as well as the formal composition mechanism that facilitates the generation of the expected behavioral model and produces a verifiable model.  Within this framework, use case approaches have been accepted in the industry because they make the process of requirements engineering simpler. In the first stage of their development, use cases have been associated with requirements gathering and domain analysis since they allow the partial description of system behavior in a more intuitive manner. During the last decade, their use has been expanded to include all phases of the lifecycle. Consequently, the model representing use cases has an increasing importance.  Although use case approaches present benefits in terms of improving the communication among stakeholders, permitting incremental construction of the system specification, and improving the requirements traceability, such approaches have some drawbacks in relation to their lack of formality. In fact, it is difficult to validate and verify use cases for completeness and consistency.  This thesis addresses the problem of modeling use cases and their composition based on formal models in order to generate a system specification that can be used for validation and verification. We tackled the problem of both composing overlapping use cases that share partial similar behaviors, and composing non overlapping use cases according to additional criteria.  We experimented with different formal models of use cases having different levels of expressivenesses to develop an approach for use case composition. All use case models we tackled are state-based models. We first started by proposing an approach for composing use cases expressed as extended finite state machines with variables that characterize their states. The use case model allows the definition of explicit loops. The state characterization is used as the criterion of composition. It allows the detection of common states between use cases that have to be merged in the overall system model. When composing, we proposed an approach that protects the user-defined loops from unexpected scenarios that may threaten their behavior.  As a second step, we proposed to compose use cases based on the interactions they are making between each other. In this context, an interaction is defined as an invocation of a use case by another. Unlike the first approach, use cases are no more considered overlapping. When composing, we developed an approach that avoids unexpected scenarios.  Finally, we proposed a general approach for composing system behaviors where partial system behaviors are defined as state based model using imperative expressions. Each use case describes a certain system concern. The imperative expression represents the composition criterion. In fact, it defines the semantics of the composition to perform. Our approach is fully automated and provides the advantage of generating a state based model that meets the intended behavior without allowing unexpected scenarios. The approach is formalized in the case of finite state machines and extended finite state machines.


identifier: Pai Screenivasan, Murali Manohar  (2008) Acousto optic modulated stroboscopic interferometer for comprehensive characterization of microstructure.  Masters thesis, Concordia University.

abstract: Mechanical and electro-mechanical advancements to the nano-scale require comprehensive and systematic testing at the micro-scale in order to understand the underlying influences that define the micro/nano-device both from fabrication and operational points of view. In this regard, surface metrology measurements, as well as static and dynamic characteristics will become very important and need to be experimentally determined to describe the system fully. These integrated tests are difficult to be implemented at dimensions where interaction with the device can seriously impact the results obtained. Hence, a characterization method to obtain valid experimental information without interfering with the functionality of the device needs to be developed. In this work, a simple yet viable Acousto Optic Modulated Stroboscopic Interferometer (AOMSI) was developed using a frequency stabilized Continuous Wave (CW) laser together with an Acousto Optic Modulator for comprehensive mechanical characterization to obtain surface, static and dynamic properties of micro-scale structures. An optimized methodology for measurement was established and sensitivity analysis was conducted. Being a whole-field technique, unlike single point or scanning interferometers, AOMSI can provide details of surface properties as well as displacements due to static/dynamic loads and modal profiles. Experiments for surface profiling were carried out on a micro-mirror, along with 2D and 3D profile measurements. The ability of AOMSI to perform dynamic measurements was tested on Micro-Cantilevers and on AFM (Atomic Force Microscopy) cantilevers. The resolution of AOMSI was identified as 10nms. The results for static deflections, 1 st and 2 nd natural frequencies and mode shapes were found to be in good agreement with results from the developed theoretical model and manufacturers specifications. The approach is a novel approach to investigate the surface, static and dynamic behavior of microstructures using a single interferometer.


identifier: Ben Khedher, Dhafer  (2007) Media handling for conferencing in MANETs.  PhD thesis, Concordia University.

abstract: Mobile Ad hoc NETworks (MANETs) are formed by devices set up temporarily to communicate without using a pre-existing network infrastructure. Devices in these networks are disparate in terms of resource capabilities (e.g. processing power, battery energy). Multihop Cellular Networks (MCNs) incorporate multihop mobile ad-hoc paradigms into 3G conventional single-hop cellular networks. Conferencing, an essential category of applications in MANETs and MCNs, includes popular applications such as audio/video conferencing. It is defined as an interactive multimedia service comprising online exchange of multimedia content among several users. Conferencing requires two sessions: a call signaling session and a media handling session. Call signaling is used to set up, modify, and tear down conference sessions. Media handling deals with aspects such as media transportation, media mixing, and transcoding. In this thesis, we are concerned with media handling for conferencing in MANETs and MCNs.  We propose an architecture based on two overlay networks: one for mixing and one for control. The first overlay is composed of nodes acting as mixers. Each node in the network has a media connection with one mixer in the first overlay. A novel distributed mixing architecture that minimizes the number of mixers in end-to-end paths is proposed as an architectural solution for this first overlay. A sub-network of nodes, called controllers, composes the second overlay. Each controller controls a set of mixers, and collectively, they manage and control the two-overlay network. The management and control tasks are assured by a media signaling architecture based on an extended version of Megaco/H.L248.  The two-overlay network is self-organizing, and thus automatically assigns users to mixers, controls mixers and controllers, and recovers the network from failures. We propose a novel self-organizing scheme that has three components: self-growing, self-shrinking and self-healing. Self-growing and self-shrinking use novel workload balancing schemes that make decisions to enable and disable mixers and controllers. The workload balancing schemes use resources efficiently by balancing the load among the nodes according to their capabilities. Self-healing detects failed nodes and recovers the network when failures of nodes with responsibilities (mixers and controllers) occur. Detection of failed nodes is based on a novel application-level failure detection architecture.  A novel architecture for media handling in MCNs is proposed. We use mediator concepts to connect the media handling entities of a MANET with the media entities of a 3G cellular network. A media mediator assures signaling and media connectivity between the two networks and acts as a translator of the different media handling protocols.


identifier: Nasery, Hesam  (2008) Fabrication of AlN-MgO-MgAl2O4 ceramic composite by spontaneous reactive infiltration.  Masters thesis, Concordia University.

abstract: Aluminum nitride ceramics are in high demand in electronic industries as substrate materials for applications requiring high thermal conductivity. Sintering and hot pressing are the most common processing methods used to make dense AlN ceramics. However, all methods of AlN sintering involve high temperatures and long times. Therefore, it is an expensive material. Removing oxygen, as a main impurity of aluminum nitride, by a low cost method in order to achieve dense and high thermal conductivity aluminum nitride ceramics has been pursued for many years.  A pressureless infiltration technique at low (650-950°C) temperature was developed to fabricate aluminum nitride-based ceramic matrix composites. The process involves forming a particulate porous compact of non-sintered aluminum nitride and introducing magnesium alloy into the channel network by spontaneous infiltration in a nitrogen atmosphere. Magnesium oxide and spinel phase (MgAl 2 O 4 ) were formed in-situ, when nitrogen gas was used. Densification, thermal properties, and microstructure of the products have been studied. Microstructural, phase, and chemical analysis show that AlN-MgO-MgAl 2 O 4 ceramic composites can be fabricated successfully. Metallic phases were not observed in the samples fabricated at higher than 800°C and electrical conductivity results show that they are insulators. Thermal diffusivity and heat capacity have been measured using nano-flash and differential scanning calorimetry techniques, respectively. Thermal conductivity results are strongly influenced by the residual porosity. Maximum thermal conductivity and density at room temperature were measured to be 95.88 W/m.K and 2.451 g/cm 3 , respectively


identifier: Benharref, Abdelghani  (2007) Passive observation-based architectures for management of web services.  PhD thesis, Concordia University.

abstract: Web Services technologies are emerging as the standard paradigm for program-to-program interactions over the Internet. A Web Service is any application that offers its functionalities through the Internet by publishing a description of its interfaces. Web Services are gaining more and more momentum and their utilization is being spread and even standardized in many areas including e -Government, e -Telecomm, e -Health, and digital imaging.  The management of Web Services will play an important role for the success of this emerging technology and its adoption by both providers and consumers. As the technology matures and spreads, consumers are likely to be very picky and restrictive with regards to the quality of the offered Web Services. Another challenging factor for the management of Web Services is related to the diversity of platforms on which Web Services are developed and deployed.  In this thesis, the focus is on the management of Web Services using passive observation with the intent to have open and platform-independent management architectures capable of assessing both functional and non-functional aspects of Web Services. The bulk of the observation process is carried out by model-based entities known as observers. These observers make use of formal model such as Finite State Machines, Communicating Finite State Machines, and Extended Finite State Machines.  The proposed architectures include observers developed and deployed as Web Services: mono-observer architecture and multi-observer architectures. A single observer is enough for observation of a non-composite Web Service while a network of observers is preferred when observing a composite Web Service. Passive observation requires traces' collection mechanisms which are thoroughly studied and their performance compared for all architectures.  A new approach for online observation based on Extended Finite State Machine is proposed to accelerate misbehaviors' detection. This approach proposes backward and forward walks in the model to reduce possible sets of states and values of variables.  I adopted a pragmatic evaluation approach to assess each of my contributions: analytical analysis and proof, implementation, and real case studies. All components of management architectures have been studied, their complexities determined, developed, and deployed. The use cases used for the evaluation of the effectiveness of the architecture, including simple and composite Web Services, are also fully implemented and deployed.


identifier: Motamedi, Zohreh  (2007) On the spectral efficiency of MIMO ad-Hoc networks.  PhD thesis, Concordia University.


identifier: Tadjalli, Alireza  (2008) Analysis, modeling and design of elliptical dielectric resonator antennas.  PhD thesis, Concordia University.


identifier: Yao, Jie  (2008) A bi-objective multi-population genetic algorithm with applications to function optimization and ellipse detection.  PhD thesis, Concordia University.

abstract: This dissertation presents a novel Bi-objective Multi-population Genetic Algorithm (BMPGA) for multimodal optimization problems. BMPGA is distinguished by its use of two separate but complementary fitness objectives designed to enhance the diversity of the overall population and exploration of the search space. This is coupled with a multi-population strategy and a clustering scheme, both of which together focus selection pressure within sub-populations, resulting in improved exploitation of promising optimum areas as well as effective identification and retention of potential optima.  The practical value of BMPGA is demonstrated in several applications. In optimization of benchmark multimodal functions, it shows clear superiority over other typical multimodal GAs: Multinational GA [1], Dynamic Niche Clustering [2] and Clearing [3], with respect to overall effectiveness, general applicability and reliability.  In the application of imagery ellipses detection, BMPGA is compared with both widely used Randomized Hough Transform (RHT) [4] and Sharing Genetic Algorithm (SGA) [5]. In thorough and fair experimental tests, utilizing both synthetic and real-world images, BMPGA exhibits solid advantages over RHT and SGA in terms of accuracy of recognition - even in the presence of noise or/and multiple imperfect ellipses in an image - and speed of computation.  Finally, we successfully extend BMPGA to the segmentation of microscopic cells, which is a necessary first step of many automated biomedical image processing procedures


identifier: Wu, Chao  (2007) Polyphase structure-based approaches for FIR Mth-band filters and constrained filter banks : design, implementation and applications.  PhD thesis, Concordia University.

abstract: Multirate systems, including M th-band filters and filter banks, have greatly facilitated the analysis, understanding and compression of signals. Polyphase structure plays an important role in the study of multirate systems due to the fact that it provides a parallel and very efficient implementation architecture. In this dissertation, some polyphase structure-based approaches for the design and implementation of M th-band filters as well as filter banks are presented. The emphasis is placed on the development of new structures that satisfy certain constraints and having low computational complexity.  A design algorithm for M th-band filters is first presented based on the generalized polyphase (GP) structure. Both the interpolation and linear-phase conditions are incorporated in the proposed GP realization of M th-band filters. By deriving a closed-form frequency response specification for each of the constituent filters in the GP structure, the design of the original large-tap FIR filter is simplified to the design of short-length constituent filters to reduce the overall design complexity. The GP-based approach is then extended for the design of M th-band filters meeting certain regularity requirements. To show the wide applicability of the proposed method, the design of 2-D M th-band filters via the GP structure is also considered. It is shown that by applying the singular-value decomposition (SVD) to each 2-D subfilter in the GP structure, the implementation complexity of the overall 2-D filter can be significantly reduced without introducing a large error.  The second part of the dissertation is concerned with the development of new lattice structures for perfect reconstruction filter banks (PRFBs) with certain constraints, such as the linear-phase (LP) and the minor-image symmetry (MIS). The innovative work is based on the polyphase matrix representation of the analysis and synthesis filters, and a key idea of devising basic building blocks that are capable of propagating the desirable symmetry properties while being cascaded to generate the required lattice structures. Due to the added constraints, the resulting lattice structures have fewer parameters, leading to a speedy optimization design and a reduction in the heavy implementation burden.  It is proved that there exists a complete and minimal lattice structure for MIS-PRFBs. It is shown that a class of well-known filter banks, namely, the cosine-modulated filter banks (CMFBs), is a subclass of MIS-PRFBs, whose non-singular matrices are of sparse coefficients. By introducing more prototype filters, in conjunction with a proper modulation, new CMFBs with more parameters are generated. Combining the linear-phase and mirror-image symmetries, a lattice structure with further reduced number of parameters is also developed for MIS-LPPRFB. The designed MIS-LPPRFB is then utilized as a block transform for image compression coding. Simulation results show that the MIS-LPPRFB, despite its reduced number of parameters, offers a competitive performance in terms of both the visual quality and the peak signal-to-noise ratio for various images under a wide range of compression ratios


identifier: Zhang, Bowei  (2007) Optical high temperature sensor based on fiber bragg grating.  PhD thesis, Concordia University.

abstract: The aim of this thesis is to fabricate a fiber Bragg grating (FBG) temperature sensor that is capable to measure temperatures in excess of 1100°C. For this purpose, two topics have been studied and investigated during this project. One of them is the development of a high temperature resistant molecular-water induced FBGs; and the other is to investigate the effect of microwave-irradiation on the hydrogen-loaded FBG.  The molecular-water induced FBGs are different from the other types of FBG. In these devices the refractive index is modulated by the periodic changes of molecular-water concentration within the grating. The device was developed using thermal annealing technology based on hydrogen-load FBG. Thermal stability of these devices was studied by measuring the grating reflectivity from room temperature to 1000°C. The stability of the device was tested by examining the FBG reflectivity for a period of time at certain temperatures. The results show that these devices are extremely stable at temperatures in excess of 1000°C.  The hydroxyl concentration in the grating has been also investigated during this thesis. Based on the knowledge of hydroxyl groups inside FBG, a microwave treatment was designed to increase the hydroxyl concentration in the FBG area. The results show that the molecular-water induced grating, which was fabricated using microwave radiated hydrogen-loaded FBI, are stable at temperatures above 1100°C


identifier: Hasan, Osman  (2008) Formal probabilistic analysis using theorem proving.  PhD thesis, Concordia University.

abstract: Probabilistic analysis is a tool of fundamental importance to virtually all scientists and engineers as they often have to deal with systems that exhibit random or unpredictable elements. Traditionally, computer simulation techniques are used to perform probabilistic analysis. However, they provide less accurate results and cannot handle large-scale problems due to their enormous computer processing time requirements. To overcome these limitations, this thesis proposes to perform probabilistic analysis by formally specifying the behavior of random systems in higher-order logic and use these models for verifying the intended probabilistic and statistical properties in a computer based theorem prover. The analysis carried out in this way is free from any approximation or precision issues due to the mathematical nature of the models and the inherent soundness of the theorem proving approach.  The thesis mainly targets the two most essential components for this task, i.e., the higher-order-logic formalization of random variables and the ability to formally verify the probabilistic and statistical properties of these random variables within a theorem prover. We present a framework that can be used to formalize and verify any continuous random variable for which the inverse of the cumulative distribution function can be expressed in a closed mathematical form. Similarly, we provide a formalization infrastructure that allows us to formally reason about statistical properties, such as mean, variance and tail distribution bounds, for discrete random variables. In order to in illustrate the practical effectiveness of the proposed approach, we consider the probabilistic analysis of three examples: the Coupon Collector's problem, the roundoff error in a digital processor and the Stop-and-Wait protocol. All the above mentioned work is conducted using the HOL theorem prover.


identifier: Paquet, Frederick  (2008) A simplified approach to condensed phase combustion modeling.  Masters thesis, Concordia University.

abstract: The combustion modeling of energetic materials still involves a guessing step due to the lack of knowledge in the condensed phase. Quantum dynamical calculations are presently the only way to predict the initial gasification reaction but require tremendous computing power, thus limiting their application. This constitutes a lack of completeness in the design of modeling tools. Through quantum mechanics, it is known that incoming energy will couple only in certain ways with a molecular system. The way this coupling is defined will depend on the selection of an energy model. A simple empirical method was devised which uses an energy coupling assumption and spectroscopic data of energetic molecules as the source for the complete modal molecular picture of the system. The method enables a qualitative prediction of the first combustion reaction through comparison with emission spectra of energy sources. The goal of this work is to present the method developed along with some results and gather tools for future research in the same subject. The thesis will first review the current state of research in the field of condensed phase energetic materials combustion. A discussion on the different theoretical foundations and assumptions used related to quantum mechanics and spectroscopy shall follow culminating with a description of the method developed. The analysis method will then be applied with two example energetic molecules nitroguanidine and nitrocellulose. The study will conclude with an explicit prediction for the two example cases followed by a discussion on future research that could be undertaken based on the conclusions drawn here.


identifier: Shen, Ani  (2008) Hot workability of iron aluminum intermetallics in comparison to ferritic steels.  Masters thesis, Concordia University.

abstract: In this project, torsion tests on hot-rolled and annealed Fe 3 Al (Fe-15.5Al-5.8Cr-1.0Nb-0.05C) were carried out over the ranges 750-950°C and 0.01{598}1s -1 . The experimental results showed that when peak stress v P >90MPa (LogZ>16 -1 , Z: temperature-compensated strain rate, Z = [Special characters omitted.] exp( Q HW / RT ) , R : universal gas constant; Q HW , :activation energy; T : absolute temperature), specimens cracked at randomly low strains. Optical microscopy exhibited original elongated grains and many grain boundary cracks associated with segregation. With v P {600}40MPa (LogZ{600}16s -1 ), specimens deformed with low random v P but considerably high fracture strains; slowly propagating cracks may explain the reduced flow stress. Optical microscopy showed both elongated grains and equiaxed subgrains with some indications of geometric dynamic recrystallization (gDRX) and of static recrystallization (SRX). Compression tests gave higher stress with little effect of the preexisting cracks. Q HW of current material in satisfactory torsion and compression tests is about 10% higher than previously published results.  Fe 3 Al has body-centered cubic structure in the experimental range, so it was compared with ferritic steel 434C (Fe- 16.55Cr-0.96Mo-0.21Ni, wt%). Ferritic steels with approximately 3.0wt%Si are of great interest in transformer applications. Isothermal continuous deformation of Fe-2.7Si-0.06C was analyzed and compared with 434C and 409C (11.0Cr-0.0lMo-0.16Ni-0.19Ti, wt%). Multi-stage deformation of the material was investigated to determine the relative softening and relative stress reduction during the intervals between successive stages. Constitutive constants and restoration mechanism were compared between the materials


identifier: Wang, Tieshan  (2008) Generic models for the integrated design of domestic and global supply chain networks with remanufacturing.  Masters thesis, Concordia University.

abstract: This research focuses on the modeling of strategic supply chain network design. Several comprehensive mixed-integer-programming models are developed for the strategic integrated design of domestic and global supply chain networks with remanufacturing capacity. The models allow simultaneous determination of supplier selection, manufacturing and distribution facility selection and allocation, production quantities, transportation flows, reverse distribution facility selection, and disassembly plant allocation. Additionally, our models incorporate bill of material (BOM) both in the manufacturing process and in disassembly process. Management policies are also considered in the model formulation so that specific management choices, such as multi- sourcing strategy or single sourcing strategy, can be fulfilled in the strategic supply chain network design. Global factors considered in the model include currency exchange rates, transfer prices, allocation of transportation costs, local content requirements, local income taxes, and tariffs. The models are verified by medium-sized numerical examples.  Compared to previous literature, the proposed models have two distinctive features. First, the corresponding integrated logistics problem of a global supply chain is formulated with a generalized mathematical form, and thus is not limited to applications for specific industries. Such a methodological measure is rare in previous literature, and has exhibited its potential advantages in addressing complicated global supply chain problems. Second, remanufacturing factors oriented from the enforcement of corresponding governmental regulations for environmental protection are considered in the proposed model. Thus, the corresponding effects may help to determine solution alternatives to improve the performance of a global supply chain with remanufacturing capacity


identifier: Farajollahi, Yashar  (2007) An experimental investigation on the indoor environmental conditions on diffusion coefficient of VOCs in building materials.  Masters thesis, Concordia University.

abstract: After the energy crisis in 1973, efforts were made to design constructions more airtight to be energy efficient. Since then, sick building syndrome (SBS) has been reported more often as a result of poor indoor air quality (IAQ). Among the proposed strategies to improve IAQ, source control is determined to be the most effective approach. Because of their large surface areas permanently exposed to the indoor environment, building materials are suspected of playing an important role in determining IAQ. Source-specific control, however, requires adequate knowledge about the extent of volatile organic compounds (VOC) emissions of materials so that in decision-making stages, only products with lower emission rates will be chosen and installed. Hence, knowing the characteristics of building materials (diffusion and partition coefficients) is necessary. Moreover, these data are needed as input parameters for VOC emission simulations, which presently suffer from the lack of a database of emission characteristics of materials. Therefore, this study has characterize building materials by measuring their diffusion coefficients ( D ) in different environmental conditions.  Based on the twin-chamber method, an experimental set-up was developed to determine the D of five VOCs (octane, isopropanol, cyclo hexane, ethyl acetate, and hexane) for ceiling tile as the building material. By using Fick's law, D was calculated and linked to physicochemical properties of VOCs. The method used also allowed us to investigate the influence of temperature, humidity, and the mixture of VOCs on D. Based on obtained results, a systematic parametric study was conducted to quantify the importance of investigated factors.  It was found that among different physicochemical properties, the D is positively related to vapor pressure. Additionally, no significant difference was observed between the D of a single VOC and that of a mixture of VOCs. Also, it was observed that temperature and humidity (in the range of a typical indoor environment) had a minor effect on the measured D


identifier: Gibbs, Bernard F  (2007) Enhanced degradation of polychlorinated biphenyls by surfactants and a dioxygenase enzyme complex.  Masters thesis, Concordia University.

abstract: There is a worldwide initiative to remove polychlorinated biphenyls (PCBs) from the environment because of their potential hazard. Animal experiments have shown they can produce liver damage, developmental defects and even cancer. Thirty per cent of the 310,000 tons of PCBs that have been produced globally are now considered as persistent toxicants in the environment. To date, only 4% have been successfully treated. Although a number of technologies are in existence for the treatment of persistent organic pollutants (POPs), they do have several drawbacks including the production of toxic volatiles in incinerators and high cost associated with these procedures. On the other hand, successful bioremediation is relatively inexpensive, as shown for polyaromatic hydrocarbons (PAH) degradation, with the added advantages of being able to be carried out in situ .  In this study, preliminary experiments demonstrated that certain surfactants enhance PCB degradation in aqueous solution in the presence of enzymes, in a concentration-dependent manner. These surfactants have not been previously reported as enhancers in PCB degradation. Conditions were optimized before experiments with soil samples were performed. A soil sample (free of PCBs) was spiked with varying amounts of PCBs and internal standards. Samples were mixed at various speeds, temperatures, incubation periods and concentrations of surfactants, before the metabolites were extracted and mass analyzed. An aged PCB-contaminated soil sample was also studied.  PCBs extraction recoveries for the spiked samples two hours after exposure to the toxicants were 93% whereas average recovery from the samples extracted after 60 days of toxicant exposure was 67%. Within 2 hours of incubation, 47, 28 and 14% of PCBs were biodegraded from the contaminated sample by the addition of surfactin, rhamnolipids and octyl glucoside respectively, at concentrations above their critical micelle concentrations. If the soil composition and mechanism for removal at a contaminated site are fully understood, in situ biodegradation can be exploited.


identifier: Mofidi, Amir  (2008) Strengthening RC T-beams in flexure and shear using new mechanically-anchored FRP and dry fibre systems.  Masters thesis, Concordia University.

abstract: Current conventional strengthening of reinforced concrete (RC) beams using epoxy-bonded fibre-reinforced polymer (FRP) technique requires difficult surface preparation and is susceptible to a brittle form of failure due to peel-off or debonding of the FRP laminate from the beam. This research presents two new mechanically-anchored FRP and dry fibre strengthening systems that can be used to improve the performance of RC beams in flexure and shear, respectively. Unlike conventional FRP-strengthening methods, the proposed systems require less surface preparation and adhesive application, and eliminate peel-off and debonding of FRP sheets. In order to experimentally evaluate the effectiveness of the new strengthening systems, a total of seven half-scale RC T-beams were tested under four-point loading system up to failure.  Three RC T-beams were tested to evaluate the increase in shear capacity using a new FRP strengthening system. One beam was tested as a control beam. One beam was strengthened by using a U-shaped carbon FRP (CFRP) sheet that was externally bonded to the web of the beam. One beam was strengthened by using new anchored U-shaped dry carbon fibre (CF) sheet method. In this method, dry CF sheets are wrapped around and bonded to two steel rods. Then the rods are anchored to the corners of the web-flange intersection of the T-beam with mechanical bolts. The new method relies on utilizing the full mechanical contribution of the dry CF sheets, which will be activated upon development of strain in the RC web, and transferring them through a longitudinal steel rod to the core of the compression web-flange zone by means of mechanical anchors.  Four RC T-beams were tested to evaluate the increase in flexural capacity and ductility using a new FRP strengthening system. One beam was tested as a control beam. One beam was strengthened with conventional epoxy-bonding method. Two beams were strengthened with the new hybrid FRP sheet / ductile anchor system (one with unbonded CFRP, while the other with bonded CFRP). The proposed system leads to a ductile failure mode by triggering the yield in the steel anchor system (steel links) while avoiding peel- off or debonding of FRP sheets, which is sudden in nature.  The tested beams where modeled to analytically evaluate their performance. The experimental and analytical results indicate that the proposed new retrofitting methods are structurally efficient in enhancing the shear and flexure strengths and ductility of RC T-beams compared to conventional epoxy-bonding methods


identifier: Sultana, Sharmin  (2007) Modeling infrastructure interdependency with extended Petri-Net and Markov chain analysis for emergency management.  Masters thesis, Concordia University.

abstract: This research introduces a novel and dynamic mathematical modeling methodology of infrastructure interdependency which has been examined through two case studies. The urban infrastructure interdependency was illustrated with a case example of California electricity outage in 2001. The developed Petri-Net model captured the interdependencies among the infrastructures in the network of a power plant, oil refinery, natural gas plant, fuel transporting pipes and tanks, water supplying pipes, and telecom. Extended Petri-Net and Markov Chain have been applied to the part of the network to assess the safety of the infrastructures. The developed modeling tools have been used to demonstrate the floodplain infrastructure interdependency with a case study of Canyon Ferry reservoir area having the infrastructures network of a water storage multi-purpose concrete gravity dam, penstock, power plant, transformer substation, intake pipes and pumping station, irrigation systems, municipal water supplying systems, and telecom. Additionally, gravity dam vulnerability assessment with empirical and analytical fragility curves and flood frequency analysis have been integrated with the extended Petri-Net analysis. The obtained results are reasonable showing that the more interdependent infrastructures present in the network, the more vulnerable they are. Also, higher degree of interdependency results in intense coupling leading towards higher vulnerability. Overall, this research contributes to the emergency management planning for safety assessment of the critical infrastructures.


identifier: Zhang, Zhi Hong  (2007) LNAPL volume in the petroleum-contaminated groundwater system-A modeling and experimental study.  Masters thesis, Concordia University.

abstract: LNAPLs, or light non-aqueous phase liquids, are less dense than water. They can co-exist with water in the aquifer, which are hydrocarbons presenting potential health, resource, and environmental risks. Examples of LNAPL are gasoline, diesel, motor oils, and similar materials.  For many decades, the oil production industry has recognized that LNAPLs accidentally released to the subsurface remain in porous media. The study of the distribution of LNAPL in contaminated soil began in the I930s. At that time, LNAPL was considered like "pancakes" over groundwater table. In the past two decades, several methods have been studied to analyze the actual LNAPL thickness present in wells or groundwater and the LNAPL volume in petroleum-contaminated sites. However, previous studies were lack of consideration of the heterogeneous characteristics of the soil. Also few model validations could be found.  A new oil volume computation method is developed in the present study, based on an integrated analysis of oil properties, the characteristics of subsurface porous media, and the interactions between oil, soil, and groundwater. Quantitative analyses and tools are thus provided to quantify LNAPL volumes residing in the petroleum-contaminated groundwater system.  Importantly, a pilot-scale experiment was set up and conducted in the Environmental Engineering laboratory at Concordia University with actual oil spills and measurements. The developed model has been tested and validated through the pilot-scale experiment and applied to a real petroleum-contaminated site. In addition, a user-friendly modeling system has been developed in the present study.  The developed modeling tool can be used to identify the field distribution of LNAPL and its volume present in the soil and groundwater system. The approach can support effective LNAPL recovery action at the contaminated site and thus help solving oil spill contamination problems for the management of groundwater resources


identifier: Xu, Xuxin  (2007) Preventing collusion attacks on the One-way Function Tree (OFT) scheme.  Masters thesis, Concordia University.

abstract: The group key management problem is an important research area in multicast communication security field. The one-way function tree (OFT) scheme proposed by Balenson et al. is widely regarded as an efficient key management solution for multicast communication in large dynamic groups. Following Horng's claim that the original OFT scheme was vulnerable to a collusion attack, Ku et al. proposed a solution to prevent the attack. The solution, however, requires to broadcast about h 2 + h ( h is the height of the key tree) keys for every eviction operation, whereas the original OFT scheme only requires about h keys. This modified OFT scheme thus loses a key advantage that the original OFT has over the logical key hierarchy (LKH) scheme, that is a halving in broadcast size.  In this thesis, we revisit collusion attacks on the OFT scheme. We generalize the examples of attacks given by Horng and Ku et al. to a generic collusion attack on OFT, and derive necessary and sufficient conditions for such an attack to exist. We then show a solution for preventing collusion attacks while minimizing the average broadcast size. Our simulation results show that the proposed solution outperforms LKH in many cases and it has an improved performance over Ku and Chen's scheme. This performance gain is due to the fact that our method requires additional key updates only when attacks become possible.  We also extend our analysis for the case where only the root (group) key needs to be protected. Using this relaxed security assumption, a more efficient key updating scheme is proposed and analyzed. Our simulation results confirm that if only the group key needs to be protected, the proposed OFT-based scheme outperforms LKH in all cases


identifier: Zhang, Ying  (2007) Entropic and statistical approaches for multimedia processing.  Masters thesis, Concordia University.


identifier: Abbas, Abdullah Omer A  (2008) Topological approaches to 3D mesh watermarking.  Masters thesis, Concordia University.

abstract: The recent rapid growth of digital media contents and the increase use of online services have triggered the need for multimedia protection. Watermarking plays an important role to solve the problem of unauthorized replication. Watermarking can be defined as the process of embedding data called "watermark" into a digital object without making changes to the quality of the host substantially. The digital object could be an image, video, or audio. The watermark is used as a signature to prove ownership and can only be detected or extracted by the owner.  This thesis is devoted to three robust watermarking techniques that we have developed for copyright protection. The first watermarking technique inserts a binary number into a set of critical points of a digital elevation map (DEM). Our method starts by extracting the critical points from a DEM depending on the important topographic features of the terrain. Then we embed the fingerprints into the coordinate values of all the critical points. The second watermarking technique partitions a 3D model into sub-meshes, then apply the eigen-decomposition to the Laplace-Beltrami matrix of each sub-mesh, followed by computing the hash value of each sub-mesh. The hash value is defined in terms of the entropy of each submesh. The last watermarking technique applies content-based hashing algorithm to the DEM using higher-order statistics and discrete wavelet transform to define the image fingerprint


identifier: Binsalleeh, Hamad  (2008) Design and implementation of a worm detection and mitigation system.  Masters thesis, Concordia University.

abstract: Internet worms are self-replicating malware programs that use the Internet to replicate themselves and propagate to other vulnerable nodes without any user intervention. In addition to consuming the valuable network bandwidth, worms may also cause other harms to the infected nodes and networks. Currently, the economic damage of Internet worms' attacks has reached a level that made early detection and mitigation of Internet worms a top priority for security professionals within enterprise networks and service providers.  While the majority of legitimate Internet services rely on the Domain Name System (DNS) to provide the translation between the alphanumeric human memorizable host names and their corresponding IP addresses, scanning worms typically use numeric IP addresses to reach their target victims instead of domain names and hence eliminate the need for DNS queries before new connections are established by the worms. Similarly, modern mass-mailing worms employ their own SMTP engine to bypass local mail servers security measures. However, they still rely on the DNS servers for locating the respective mail servers of their intended victims. Creating host-based Mail eXchange (MX) requests is a violation of the typical communication pattern because these requests are supposed to only take place between mail servers and DNS servers. Several researchers have noted that the correlation of DNS queries with outgoing connections from the network can be utilized for the detection zero-day scanning worms and mass-mailing worms.  In this work, we implement an integrated system for the detection and mitigation of zero-day scanning and mass-mailing worms. The detection engine of our system utilizes the above mentioned DNS anomalies of the worm traffic. Once a worm is detected, the firewall rules are automatically updated in order to isolate the infected host. An automatic alert is also sent to the user of the infected host. The system can be configured such that the user response to this alert is used to undo the firewall updates and hence helps reduce the interruption of service resulting from false alarms.  The developed system has been tested with real worms in a controlled network environment. The obtained experimental results confirm the soundness and effectiveness of the developed system