Cyber-physical systems (CPSs) represent a new generation of engineered systems that tightly integrates computations, communications (cyber) and physics. Simulation plays a considerable role in validating CPSs as it substantially reduces the costs and risks in the design-testing cycles. Reliable simulations, however, mandate realistic modeling for both the cyber and the physical aspects. This is especially the case in various networked mobile CPSs (e.g., excavation robots and vehicular networks), where cost and risk may become substantial. Current CPS modeling tools lack complete models of communication. Co-simulation attempts to overcome this limitation by integrating multiple modeling and simulation tools to offer complete models of all aspects of CPSs. In this thesis, we design and implement a co-simulation environment for modeling and simulating networked CPSs. The environment is called AcumenNS3 and it integrates Acumen, a language for modeling hybrid physical systems, with NS-3, a discrete-event network simulator. This environment allows users to augment network simulations with physical models using an easy-to-use modeling language. It provides a seamless integration between network and physics models by providing mobility based on the physical simulation in addition to generic access to the physical state. Using the AcumenNS3 environment, we demonstrate and model example simulation scenarios of networked CPSs. / Thesis (Master, Computing) -- Queen's University, 2014-04-24 14:38:30.039

Numerical oceanographic models are constantly improving and must be validated when improvements are made. One means of determining how to improve these models and performing validations is to compare model predictions to the future observed outcome, which is measured many ways, including satellite imagery. Comparisons of model forecasts to future satellite images result in error measurements. One common problem with modern oceanographic models is spatial error, i.e., the incorrect placement and shape of ocean features, rendering traditional error metrics such as mean-square and cross-correlation ineffective. Such problems are common in meteorological forecast verification as well, so the application of spatial error metrics have been a recently popular topic in that field of study. Spatial error metrics separate model error into a displacement component and an amplitude component, providing a more reliable assessment of numerical model inaccuracies and a more descriptive portrayal of model prediction skill.The application of spatial error metrics to oceanographic models has been sparse, and significantly further advances exist in the medical imaging and registration field. These advances are presented, along with modifications necessary for application to oceanographic model output and satellite imagery. Standard approaches and options for those methods in the literature are explored, and where the best arrangements of options are unclear, comparison studies are conducted. The first of these trials require the reproduction of synthetic displacements in conjunction with synthetic amplitude perturbations across 480 Navy Coastal Ocean Model (NCOM) temperature fields from various regions of the globe throughout 2009. Results revealed the success of certain approaches novel to both meteorology and oceanography, including B-spline transforms and mutual information. That, combined with other common methods, such as quasi-Newton optimization and land masking, could best recover the synthetic displacements under various synthetic intensity changes. The second set of trials compare temperature fields from NCOM and Navy Layered Ocean Model (NLOM), both 1/16-degree and 1/32-degree, to Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. Lessons learned from the first trials were applied and extended. The resulting methods algorithmically reproduced portions of a previous hand-analyzed study and were successful in separating spatial from amplitude (temperature) errors.

Urban activities involving planning, preparing for and responding to time critical situations often demands sound situational awareness of overall settings. Decision makers, who are tasked to respond effectively to emergencies, must be equipped with information on the details of what is happening, and must stay informed with updates as the event unfolds and remain attentive to the extent of impact the dynamics of the surrounding settings might have. Recent increases in the volumes of geo-spatial data such as satellite imageries, elevation maps, street-level photographs and real-time imageries from remote sensory devices affect the way decision makers make assessments in time-critical situations. When terrain related spatial information are presented accurately, timely, and are augmented with terrain analysis such as viewshed computations, enhanced situational understanding could be formed. Painting such enhanced situational pictures, however, demands efficient techniques to process and present volumes of geo-spatial data. Modern Graphics Processing Units (GPUs) have opened up a wide field of applications far beyond processing millions of polygons. This dissertation presents approaches that harness graphics rendering techniques and GPU programmability to visualize urban terrain with accuracy, viewshed analysis and real-time imageries. The GPU ray tracing and image fusion visualization techniques presented herein have the potential to aid in achieving enhanced urban situational awareness and understanding. Current state of the art polygon based terrain representations often use coarse representations for terrain features of less importance to improve rendering rate. This results in reduced geometrical accuracy for selective terrain features that are considered less critical to the visualization or simulation needs. Alternatively, to render highly accurate urban terrain, considerable computational effort is needed. A compromise between achieving real-time rendering rate and iv accurate terrain representations would have to be made. Likewise, computational tasks involved in terrain-related calculations such as viewshed analysis are highly computational intensive and are traditionally performed at a non-interactive rate. The first contribution of the research involves using GPU ray tracing, a rendering approach, conventionally not employed in the simulation community in favor of rasterization, to achieve accurate visualization and improved understanding of urban terrain. The efficiency of using GPU ray tracing is demonstrated in two areas, namely, in depicting complex, large scale terrain and in visualizing viewshed terrain effects at interactive rate. Another contribution entails designing a novel approach to create an efficient and real-time mapping system. The solution achieves updating and visualizing terrain textures using 2D georeferenced imageries for enhanced situational awareness. Fusing myriad of multi-view 2D inputs spatially for a complex 3D urban scene typically involves a large number of computationally demanding tasks such as image registrations, mosaickings and texture mapping. Current state of the art solutions essentially belongs to two groups. Each strives to either provide near real-time situational pictures in 2D or off-line complex 3D reconstructions for subsequent usages. The solution proposed in this research relies on using prior constructed synthetic terrains as backdrops to be updated with real-time geo-referenced images. The solution achieves speed in fusing information in 3D. Mapping geo-referenced images spatially in 3D puts them into context. It aids in conveying spatial relationships among the data. Prototypes to evaluate the effectiveness of the aforementioned techniques are also implemented. The benefits of augmenting situational displays with viewshed analysis and real-time geo-referenced images in relation to enhancing the user's situational awareness are also evaluated. Preliminary results v from user evaluation studies demonstrate the usefulness of the techniques in enhancing operators' performances, in relation to situational awareness and understanding.

Flight testing has been the historical standard for determining aircraft airworthiness - however, increases in the cost of flight testing and the accuracy of inexpensive CFD promote certification by analysis to reduce or replace flight testing. A framework is introduced to predict the performance in the special case of a modification to an existing, previously certified aircraft. This framework uses a combination of existing flight test or high fidelity data of the original aircraft as well as lower fidelity data of the original and modified configurations. Two methods are presented which estimate the model form uncertainty of the modified configuration, which is then used to conduct non-deterministic simulations. The framework is applied to an example aircraft system with simulated flight test data to demonstrate the ability to predict the performance and associated uncertainty of modified aircraft configurations. However, it is important that the models and methods used are applicable and accurate throughout the intended use domain. The factors and limitations of the framework are explored to determine the range of applicability of the framework. The effects of these factors on the performance and uncertainty results are demonstrated using the example aircraft system. The framework is then applied to NASA's X-57 Maxwell and each of its modifications. The estimated performance and associated uncertainties are then compared to the airworthiness criteria to evaluate the potential of the framework as a component to the certification by analysis process. / Doctor of Philosophy / Aircraft are required to undergo an airworthiness certification process to demonstrate the capability for safe and controlled flight. This has historically been satisfied by flight testing, but there is a desire to use computational analysis and simulations to reduce the cost and time required. For aircraft which are based on an aircraft which has already been certified, but contain minor changes, computational tools have the potential to provide a large benefit. This research proposes a framework to estimate the flight performance of these modified aircraft using inexpensive computational or ground based methods and without requiring expensive flight testing. The framework is then evaluated to ensure that it provides accurate results and is suitable for use as a supplement to the airworthiness certification process.

Global pressure to reduce greenhouse gas (GHG) emissions, energy security concerns and increasing demand for liquid fuels incentivize the search for more sustainable and secure alternative methods for producing liquid fuels with improved efficiency and reduced environmental impacts. One of the economically attractive examples of these alternate methods is the gas-to-liquid process, however, its environmental impacts are worse than traditional petroleum refining. Carbon capture and sequestration is an option to reduce greenhouse gas emissions of processes, but it decreases the efficiency of the process and often results in economic infeasibility. Instead, integrating different processes and feedstocks was demonstrated to improve the efficiency, economic and environmental performance of the processes. The focus of this thesis is to design and simulate a novel integrated biomass, gas, nuclear to liquids (BGNTL) process with negative greenhouse gas emissions. In this process, nuclear heat from a high temperature gas-cooled reactor (HTGR) is used as the heat source for a steam methane reforming (SMR) process. The integrated HTGR and SMR process requires detailed analysis and modeling to address key challenges on safety, operability, economic and environmental impacts of the integrated process. To this end, a rigorous first principle based mathematical model was developed in gPROMS modeling environment for the integrated HTGR/SMR process. The results for a large scale design of this system indicate that hydrogen rich syngas with H2/CO ratio in the range of 6.3 can be achieved. To meet the desired H2/CO ratio (around 2) required for the downstream fuel synthesis processes, the HTGR/SMR derived syngas can be blended with a hydrogen lean syngas from biomass gasification. In this thesis, the large scale design of the BGNTL process to synthesize gasoline, diesel and dimethyl ether (DME) is investigated. The results from the gPROMS model of the integrated HTGR/SMR system are used for simulating the BGNTL process in Aspen Plus. The performance of the BGNTL process was compared with a biomass, gas to liquids (BGTL) process. The efficiency, economics, and environmental impact analyses show that the BGNTL process to produce DME is the most efficient, economic and environmentally friendly process among all the considered designs. The results demonstrate that process integration exploits certain synergies that leads to significantly higher carbon and energy efficiencies and lower greenhouse gas emissions. In addition, it was found that all the studied designs yield a net negative greenhouse gas emissions when carbon capture and storage technology is implemented. As another sustainable alternative to meet the required H2/CO ratio of the syngas when biomass resources are not available, it is proposed to apply the nuclear heat to the mixed reforming of methane. This represents using steam and waste CO2 to reform methane into valuable syngas. The developed model for the integrated HTGR/SMR system is extended to the mixed reforming of methane (MRM) process and it was demonstrated that integrated HTGR/MRM process can be a promising option to achieve certain desired H2/CO ratios for the downstream energy conversion processes. / Thesis / Doctor of Philosophy (PhD)

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / We discuss how aspects of telemetry can be effectively incorporated and modeled as a component within network-centric operations and warfare paradigms. Telemetry is particularly vital in Air Force Flight Test and Evaluation. As such, this paper has a specific emphasis and provides discussion within this domain. We also present how an existing framework for networkcentric operations and warfare can be particularly beneficial to telemetry modeling, and discuss the potential insights and utility within this context.

The powertrain design and control strategies for three representative hybrid and plug-in hybrid electric vehicles (HEV/PHEVs), a plug-in hybrid passenger car, a plug-in hybrid race car, and a hybrid electric mining truck, have been investigated through the system modeling, simulation and design optimization. First, the pre-transmission gen-set couple Plug-in Series-Parallel Multi-Regime (SPMR) powertrain architecture was selected for PHEV passenger car. Rule-based load following control schemes based on engine optimal control strategy and Equivalent Consumption Minimization Strategy (ECMS) were used for the operation control of the passenger car PHEV powertrain. Secondly, the rear wheel drive (RWD) post-transmission parallel through road powertrain architecture was selected for race car PHEV. A high level supervisory control system and ECMS control strategy have been developed and implemented through the race car’s on-board embedded controller using dSPACE MicroAutobox II. In addition, longitudinal adaptive traction control has been added to the vehicle controller for improved drivability and acceleration performance. At last, the feasibility and benefits of powertrain hybridization for heavy-duty mining truck have been investigated, and three hybrid powertrain architectures, series, parallel and diesel-electric, with weight adjusting propulsion system have been modeled and studied. The research explored the common and distinct characteristics of hybrid electric propulsion system technology for different vehicular applications, and formed the foundation for further research and development. / Graduate / 0540 / ruicheng@uvic.ca

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / An integrated design, Test and Evaluation (T&E) system for GPS receiver is proposed in the paper, which can perform T&E early in R&D cycle, and combine new designs into a conceptual GPS receiver directly. The flowchart of its development mode is given. The architectures of the system, especially of the signal-computing software are described with frame diagrams. The mathematical models of three reference points are derived, with the impact of oscillator errors modeled. Future plans and further developments are also discussed.

A partir de la définition d'un paradigme espaces - processus énonçant que tout système peut se définir comme une combinaison espaces - processus, les espaces contenant toutes les conditions et moyens nécessaires à l'achèvement du processus, le travail proposé définit une approche modélisatrice permettant de conserver une démarche purement systémique depuis l'identification des concepts du système jusqu'au modèle de représentation. Ce paradigme exprimant simplement qu'un système peut être vu à travers le comportement des différentes propriétés des entités intervenantes, le mémoire va proposer une représentation unifiée de la propriété permettant la manipulation conceptuelle et sémantique. Une forme de représentation des comportements des propriétés sera ensuite proposée. Cette représentation sera définie à partir de l'expression d'un comportement sous forme d'expressions rationnelles; ces expressions étant elles-mêmes des suites de symboles représentatives des propriétés du système observé. Le mémoire montrera comment la forme de représentation proposée permet de retranscrire et d'exploiter simplement les comportements observés ou observables. Le mémoire montrera comment manipuler ces éléments et quelles propriétés s'en dégagent. En particulier, le premier objectif de ce travail est une application à la maîtrise des risques systèmes, on exploitera donc le modèle dans la recherche et l'identification de situations dangereuses mais aussi pour la capacité d'évaluation des critères d'occurrence par un transfert de l'espace de propriétés vers un espace de probabilités.

The pi-calculus [61] is one the most influential formalisms for modelling and analyzing the behaviour of concurrent systems. This calculus provides a language in which the structure of terms represents the structure of processes together with an operational semantics to represent computational steps. For example, the parallel composition term P | Q, which is built from the terms P and Q, represents the process that results from the parallel execution of the processes P and Q. Similarly, the restriction (v x)P represents a process P with local resource x. The replication !P can be thought of as abbreviating the parallel composition P | P | . . . of an unbounded number of P processes. As for other language-based formalisms (e.g., logic, formal grammars and the pi-calculus) a fundamental part of the research in process calculi involves the study of the expressiveness of fragments or variants of a given process calculus. In this dissertation we shall study the expressiveness of some variants of the pi-calculus focusing on the role of the terms used to represent local and infinite behaviour, namely restriction and replication. The first part of this dissertation is devoted to the expressiveness of the zero-adic variant of the (polyadic) pi-calculus, i.e., CCS with replication (CCS!) [21]. Busi et al [22] show that CCS! is Turing powerful [22]. The result is obtained by encoding Random Access Machines (RAMs) in CCS!. The encoding is said to be non-faithful because it may move from a state which can lead to termination into a divergent one which do not correspond to any configuration of the encoded RAM. I.e., the encoding is not termination preserving. In this dissertation we shall study the existence of faithful encodings into CCS! of models of computability strictly less expressive than Turing Machines. Namely, grammars of Types 1 (Context Sensitive Languages), 2 (Context Free Languages) and 3 (Regular Languages) in the Chomsky Hierarchy. We provide faithful encodings of Type 3 grammars. We show that it is impossible to provide a faithful encoding of Type 2 grammars and that termination-preserving CCS! processes can generate languages which are not Type 2. We finally conjecture that the languages generated by termination-preserving CCS! processes are Type 1 . We also observe that the encoding of RAMs [22] and several encoding of Turing-powerful formalisms in pi-calculus variants may generate an unbounded number of restrictions during the simulation of a given machine. This unboundedness arises from having restrictions under the scope of replication (or recursion) as in e.g., !(v x)P or μX.(v x)(P | X). This suggests that such an interplay between these operators is fundamental for Turing completeness. We shall also study the expressive power of restriction and its interplay with replication. We do this by considering several syntactic variants of CCS! which differ from each other in the use of restriction with respect to replication. We consider three syntactic variations of CCS! which do not allow the generation of unbounded number of restrictions: C2 is the fragment of CCS! not allowing restrictions under the scope of a replication, C3 is the restriction-free fragment of CCS!. The third variant is C4 which extends C2 with Phillips' priority guards [76]. We shall show that the use of an unboundedly many restrictions in CCS! is necessary for obtaining Turing expressiveness in the sense of Busi et al [22]. We do this by showing that there is no encoding of RAMs into C2 which preserves and reflects convergence. We also prove that up to failures equivalence, there is no encoding from CCS! into C2 nor from C2 into C3. Thus up to failures equivalence, we cannot encode a process with an unbounded number of restrictions into one with a bounded number of restrictions, nor one with a bounded number of restrictions into a restriction-free process. As lemmata for the above results we prove that convergence is decidable for C2 and that language equivalence is decidable for C3 but undecidable for C2. As corollary it follows that convergence is decidable for restriction-free CCS. Finally, we show the expressive power of priorities by providing a faithful encoding of RAMs in C4 thus bearing witness to the expressive power of Phillips' priority guards [76]. The second part of this dissertation is devoted to expressiveness of the asynchronous monadic pi-calculus, A [15, 47]. In [70] the authors studied the expressivenessn of persistence in Api [15, 47] wrt weak barbed congruence. The study is incomplete because it ignores divergence. We shall present an expressiveness study of persistence in Api wrt De Nicola and Hennessy's testing scenario which is sensitive to divergence. Following [70],,we consider Api and three sub-languages of it, each capturing one source of persistence: the persistent-input Api-calculus (PIA), the persistent-output Api-calculus (POA) and the persistent Api-calculus (PA). In [70] the authors showed encodings from Api into the semi-persistent calculi (i.e., POA and PIA) correct wrt weak barbed congruence. We show that, under some general conditions related to compositionality of the encoding and preservation of the infinite behaviour, there cannot be an encoding from Api into a (semi)-persistent calculus preserving the must testing semantics. We also prove that convergence and divergence are decidable for POA (and PA). As a consequence there is no encoding preserving and reflecting divergence or convergence from Api into POA (and PA). This study fills a gap on the expressiveness study of persistence in A in [70].