A requirements analysis approach for addressing the functional requirements of embedded systems has been proposed. Also proposed is a design approach based on the concurrent object-oriented programming paradigm. The design approach takes a specification created using the requirements analysis approach and transforms it into a detailed design. The detailed design is implemented using ACf++, a concurrent C++ that derives its concurrency semantics from the Actor model. The two approaches are illustrated by a simple but representative process control problem. The requirements analysis approach in conjunction with the design approach provides a high level of traceability and promotes the reusability of specifications and design. Improved reliability and reduced development and maintenance costs also are potential benefits. Extensions of the work include an integrated software development environment for embedded systems. / Master of Science

Yes

WebAssembly (Wasm) is an emerging technology for web development that has garnered significant popularity in web-based applications. It enables web browsers to execute codewritten in multiple languages seamlessly, delivering high performance across different platforms. With the introduction of The WebAssembly System Interface (WASI), facilitating the execution of Wasm beyond the confines of the web, Wasm is gaining traction in cloud computing as well. Recently, Docker introduced the support of running Wasm binaries in a container runtime using WasmEdge. This thesis investigates the performance implications and the usability benefits/issues of Wasm in container runtimes using WasmEdge compared to traditional Linux containers. To assess these aspects, two separate applications are utilized within the containers: the first application, inspired by the TPC-C benchmark, is created from the ground up to mimic a database workload, whereas the second application is WordPress, a widely adopted content management system. In evaluating the performance implications of Wasm containers, our experiments focus on gathering metrics relevant to container usage and management. These include image size, start-up times, CPU utilization, latency, and throughput differences between Wasm containers and traditional Linux containers. Additionally, we assess the usability of Wasm containers by examining aspects such as building, managing, deploying, portability, and language support. The finding of the thesis indicates that Wasm containers feature lower image sizes, up to 500% smaller image sizes than the Linux containers, and can improve cold-start times by 160%. However, due to the lack of multi-threading support of Wasm, the application performance becomes significantly degraded, resulting in increased latencies and reduced throughput compared to traditional containers. Furthermore, we underscore the portability advantage of Wasm containers over traditional ones in terms of usability. Nonetheless, the current language limitations of Wasm present more challenges than benefits compared totraditional containers.

Within the context of Industry 4.0, many devices have become more intelligent and connected, leading to challenges on how to meet the stringent requirements on latency and reliability in networks of critical cyber-physical systems. In particular, timely channel access and high reliability are of essence to guarantee real-time deadlines. To this end, time-division multiple-access (TDMA) schemes are often used in industrial applications to get contention-free access to the channel. Using pairwise non-orthogonal multiple access (NOMA) on top of such an existing TDMA scheme has recently emerged as a promising solution. With pairwise NOMA, two nodes are served simultaneously using the same time-frequency resources but with different power levels. To separate the signals, successive interference cancellation is used at the receiver. In addition, by adjusting the power allocation, pairwise NOMA can easily switch to TDMA by assigning zero power to one user, if and when needed. Due to this flexibility, pairwise NOMA can be integrated into existing wireless networks and schedulers with improved performance as a result. In particular, if pairwise NOMA could be tailored to the requirements of systems of collaborating cyber-physical systems, it would be possible to enhance performance in terms of latency and reliability, while still providing timely channel access to critical users using TDMA. This is the scope of the thesis work. In order to evaluate the communication reliability for each user in the system as well as for the overall system, the individual outage probability (IOP) and the overall outage probability (OOP) are of essence, but have so far not been available for pairwise NOMA used on top of TDMA. In this thesis work, closed-form expressions for the IOP and the OOP of both uplink and downlink NOMA are derived – also in the presence of a mobile smart jammer. Using these performance metrics, insightful guidelines on the impact of some key parameters on the communication reliability such as power allocation, decoding order, node placements and so on are provided. It should be noted that the conclusions on node placement can be used for smart user pairing, but also for placement of access points (AP) or even mobile APs, using a UAV. Moreover, by formulating a non-cooperative game between a malicious smart mobile jammer and a friendly mobile AP serving two friendly sensor nodes simultaneously, Nash equilibrium points are obtained to reduce power consumption for the AP, while satisfying the communication reliability requirements. Using the derived expressions for OOP and IOP to select proper settings for pairwise NOMA, it is shown that NOMA can be tailored to ensure user fairness, provide timely channel access and high reliability, which is useful for enhancing performance of critical cyber-physical systems even in the presence of jamming.

Den gemene svensken befinner sig allt oftare i digitala miljöer, inte minst i sociala medier. En inblick i dessa medier visar en mörkare sida som inkluderar kränkningar, sexuella trakasserier och andra kriminella handlingar. Snapchat är en av många samlingspunkter för dessa aktiviteter, bland annat för dess inbyggda funktion som automatiskt raderar meddelanden efter en viss tid. Men är datan verkligen raderad? Går det att skapa ett verktyg som gör det lika lätt att återställa datan som att radera den? Målet med denna uppsats är att utforska hur extraheringen av raderade meddelanden i Snapchat kan automatiseras, i syfte att underlätta IT-forensiska utredningar och minska IT-forensikerns höga arbetsbelastning. Resultatet visar att raderade meddelanden förekommer i filsystemet, med tillräcklig struktur för att ett skript ska kunna skrivas som automatiskt extraherar dessa tillsammans med resterande icke-raderade meddelanden. / <p>Källkod till programmet ReSnap:</p><p>https://github.com/8urle/ReSnap</p>

published_or_final_version / abstract / Computer Science and Information Systems / Master / Master of Philosophy

With the increasing demand for online learning, well-designed computer online learning resources are indispensable. User interfaces evaluation has become a critical quality attribute of interactive software intended to meet the requirements of the user groups. It is this aspect of adaptations that make them critical for the study of evaluation of user interfaces. This study describes a preliminary evaluation of the user interface design of a new online learning resource (Open Learning System). The main objectives of the study are to investigate the effect of the interaction on the user (usability, efficiency, effectiveness and satisfaction), to assess the extent of the system (resource) functionality and to identify specific problems in the design (aspects of design that cause unexpected results or confusion). This will form part of iterative design and testing process of the new interface, which seeks to evaluate the success of the interface within the framework of the fundamental HCI principles under guidelines of the constructivists learning approach. The Open Learning System (OLS) is grounded on the constructivist-based learning approach. The underlying philosophy of the system assumes when learners are engaged in a social learning context, they actively construct knowledge, therefore the resource is considered as a tool to support learning and not an end in itself. By so doing it is geared to provide greater access to information, support Computer-Mediated Communication (CMC) using tools such as e-mail, chat and discussion foruI? and creating context for learners' work and peer review. A theoretical framework for evaluating the OLS was developed and proposed which comprised of the constructivist epistemology, Rich Environment for Active Learning (REAL), the User Centred Design (UCD) approach and the Human Computer Interface (HCI) design principles. This integrated theoretical framework has been referred to as 'Designing-by-Constructivism' model. The study investigates the use of the OLS by two sets of users: staff members (module creators) and learners (module consumers). In view of the fact that the data collected is qualitative, the approach assumes the use of semi-structured questionnaires, evaluation matrix and interviews. The information/feedback gathered will assist the developers to do preliminary reviews. The study will also be useful to academics pursuing more HCI issues or those with an interest in developing learning resources. The main elements of the 'Designing-by-Constructivism' model were present in the resource. The results analysis indicates that the resource supports collaborative learning and the use of authentic activities in learning. This serves as an intrinsic motivation to most of the users. The results also show a high degree of user satisfaction and appreciation of OLS resource. Largely, the participants are satisfied that the overall OLS design met their needs. The major contribution being, "OLS is interactive and user friendly". However, some users have expressed the desire to have more tools incorporated into the resource, while others have expressed concern about difficulties in logging into the system. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

Wireless sensor networks are used in areas that are inaccessible, inhospitable or for continuous monitoring. The main use of such networks is for event detection. Event detection is used to monitor a particular environment for an event such as fire or flooding. Composite event detection is used to break down the detection of the event into the specific conditions that need to be present for the event to occur. Using this method, each sensor node does not need to carry every sensing component necessary to detect the event. Since energy efficiency is important the sensor nodes need to be scheduled so that they consume [sic] consume as little energy as possible to extend the network lifetime. In this thesis, a solution to the sensor Scheduling for Composite Event Detection (SCED) problem will be presented as a way to improve the network lifetime when using composite event detection. / by Arny I. Ambrose. / Thesis (M.S.C.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.

Multimodal systems can represent and manipulate semantics from different human communication modalities at different levels of abstraction, in which multimodal integration is required to integrate the semantics from two or more modalities and generate an interpretable output for further processing. In this work, we develop a framework pertaining to automatic cross-modality semantic integration of multimodal user interactions using speech and pen gestures. It begins by generating partial interpretations for each input event as a ranked list of hypothesized semantics. We devise a cross-modality semantic integration procedure to align the pair of hypothesis lists between every speech input event and every pen input event in a multimodal expression. This is achieved by the Viterbi alignment that enforces the temporal ordering and semantic compatibility constraints of aligned events. The alignment enables generation of a unimodal paraphrase that is semantically equivalent to the original multimodal expression. Our experiments are based on a multimodal corpus in the navigation domain. Application of the integration procedure to manual transcripts shows that correct unimodal paraphrases are generated for around 96% of the multimodal inquiries in the test set. However, if we replace this with automatic speech and pen recognition transcripts, the performance drops to around 53% of the test set. In order to address this issue, we devised the hypothesis rescoring procedure that evaluates all candidates of cross-modality integration derived from multiple recognition hypotheses from each modality. The rescoring function incorporates the integration score, N-best purity of recognized spoken locative references (SLRs), as well as distances between coordinates of recognized pen gestures and their interpreted icons on the map. Application of cross-modality hypothesis rescoring improved the performance to generate correct unimodal paraphrases for over 72% of the multimodal inquiries of the test set. / We have also performed a latent semantic modeling (LSM) for interpreting multimodal user input consisting of speech and pen gestures. Each modality of a multimodal input carries semantics related to a domain-specific task goal (TG). Each input is annotated manually with a TG based on the semantics. Multimodal input usually has a simpler syntactic structure and different order of semantic constituents from unimodal input. Therefore, we proposed to use LSM to derive the latent semantics from the multimodal inputs. In order to achieve this, we characterized the cross-modal integration pattern as 3-tuple multimodal terms taking into account SLR, pen gesture type and their temporal relation. The correlation term matrix is then decomposed using singular value decomposition (SVD) to derive the latent semantics automatically. TG inference on disjoint test set based on the latent semantics achieves accurate performance for 99% of the multimodal inquiries. / Hui, Pui Yu. / Adviser: Helen Meng. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 294-306). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Due to the rapidly increasing complexity in hardware designs and competitive time to market trends in the industry, there is an inherent need to move designs to a higher level of abstraction. Behavioral Synthesis is the process of automatically compiling such Electronic System Level (ESL) designs written in high-level languages such as C, C++ or SystemC into Register-Transfer Level (RTL) implementation in hardware description languages such as Verilog or VHDL. However, the adoption of this flow is dependent on designers' faith in the correctness of behavioral synthesis tools. Loop pipelining is a critical transformation employed in behavioral synthesis process, and ubiquitous in commercial and academic behavioral synthesis tools. It improves the throughput and reduces the latency of the synthesized hardware. It is complex and error-prone, and a small bug can result in faulty hardware with expensive ramifications. Therefore, it is critical to certify the loop pipelining transformation so that designers can trust the behaviorally synthesized pipelined designs. Certifying a loop pipelining transformation is however, a major research challenge because there is a huge semantic gap between the input sequential design and the output pipelined implementation, making it infeasible to verify their equivalence with automated sequential equivalence checking (SEC) techniques. Complex loop pipelining transformations can be certified by a combination of theorem proving and SEC: (1) creating a certified pipelining algorithm which generates a reference pipeline model by exploiting pipeline generation information from the synthesis flow (e.g. the iteration interval of a generated pipeline) and (2) conduct SEC between the synthesized pipeline and this reference model. However, a key and arguably, the most complex component of this approach is the development of a formal, mechanically verifiable loop pipelining algorithm. We show how to systematically construct such an algorithm, and carry out its verification using the ACL2 theorem prover. We propose a framework of certified pipelining primitives which are essential for designing pipelining algorithms. Using our framework, we build a certified loop pipelining algorithm. We also propose a key invariant in certifying this algorithm, which links sequential loops with their pipelined counterparts. This is unlike other invariants that have been used in proofs of microprocessor pipelines so far. This dissertation provides a framework for creating certified pipelining algorithms utilizing a mechanical theorem prover. Using this framework, we have developed a certified loop pipelining algorithm. This certified algorithm is essential in the overall approach to certify behaviorally synthesized pipelined designs. We demonstrate the scalability and robustness of our algorithm on several ESL designs across various domains.