Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

Efficient openMP over sequentially consistent distributed shared memory systems

Nowadays clusters are one of the most used platforms in High Performance Computing and most programmers use the Message Passing Interface (MPI) library to program their applications in these distributed platforms getting their maximum performance, although it is a complex task. On the other side, OpenMP has been established as the de facto standard to program applications on shared memory platforms because it is easy to use and obtains good performance without too much effort. So, could it be possible to join both worlds? Could programmers use the easiness of OpenMP in distributed platforms? A lot of researchers think so. And one of the developed ideas is the distributed shared memory (DSM), a software layer on top of a distributed platform giving an abstract shared memory view to the applications. Even though it seems a good solution it also has some inconveniences. The memory coherence between the nodes in the platform is difficult to maintain (complex management, scalability issues, high overhead and others) and the latency of the remote-memory accesses which can be orders of magnitude greater than on a shared bus due to the interconnection network. Therefore this research improves the performance of OpenMP applications being executed on distributed memory platforms using a DSM with sequential consistency evaluating thoroughly the results from the NAS parallel benchmarks. The vast majority of designed DSMs use a relaxed consistency model because it avoids some major problems in the area. In contrast, we use a sequential consistency model because we think that showing these potential problems that otherwise are hidden may allow the finding of some solutions and, therefore, apply them to both models. The main idea behind this work is that both runtimes, the OpenMP and the DSM layer, should cooperate to achieve good performance, otherwise they interfere one each other trashing the final performance of applications. We develop three different contributions to improve the performance of these applications: (a) a technique to avoid false sharing at runtime, (b) a technique to mimic the MPI behaviour, where produced data is forwarded to their consumers and, finally, (c) a mechanism to avoid the network congestion due to the DSM coherence messages. The NAS Parallel Benchmarks are used to test the contributions. The results of this work shows that the false-sharing problem is a relative problem depending on each application. Another result is the importance to move the data flow outside of the critical path and to use techniques that forwards data as early as possible, similar to MPI, benefits the final application performance. Additionally, this data movement is usually concentrated at single points and affects the application performance due to the limited bandwidth of the network. Therefore it is necessary to provide mechanisms that allows the distribution of this data through the computation time using an otherwise idle network. Finally, results shows that the proposed contributions improve the performance of OpenMP applications on this kind of environments

Simulation Modelling of Distributed-Shared Memory Multiprocessors

Institute for Computing Systems ArchitectureDistributed shared memory (DSM) systems have been recognised as a compelling platform for parallel computing due to the programming advantages and scalability. DSM systems allow applications to access data in a logically shared address space by abstracting away the distinction of physical memory location. As the location of data is transparent, the sources of overhead caused by accessing the distant memories are difficult to analyse. This memory locality problem has been identified as crucial to DSM performance. Many researchers have investigated the problem using simulation as a tool for conducting experiments resulting in the progressive evolution of DSM systems. Nevertheless, both the diversity of architectural configurations and the rapid advance of DSM implementations impose constraints on simulation model designs in two issues: the limitation of the simulation framework on model extensibility and the lack of verification applicability during a simulation run causing the delay in verification process. This thesis studies simulation modelling techniques for memory locality analysis of various DSM systems implemented on top of a cluster of symmetric multiprocessors. The thesis presents a simulation technique to promote model extensibility and proposes a technique for verification applicability, called a Specification-based Parameter Model Interaction (SPMI). The proposed techniques have been implemented in a new interpretation-driven simulation called DSiMCLUSTER on top of a discrete event simulation (DES) engine known as HASE. Experiments have been conducted to determine which factors are most influential on the degree of locality and to determine the possibility to maximise the stability of performance. DSiMCLUSTER has been validated against a SunFire 15K server and has achieved similarity of cache miss results, an average of +-6% with the worst case less than 15% of difference. These results confirm that the techniques used in developing the DSiMCLUSTER can contribute ways to achieve both (a) a highly extensible simulation framework to keep up with the ongoing innovation of the DSM architecture, and (b) the verification applicability resulting in an efficient framework for memory analysis experiments on DSM architecture

Sensitivity analysis in a scoping review on police accountability : assessing the feasibility of reporting criteria in mixed studies reviews

In this paper, we report on the findings of a sensitivity analysis that was carried out within a previously conducted scoping review, hoping to contribute to the ongoing debate about how to assess the quality of research in mixed methods reviews. Previous sensitivity analyses mainly concluded that the exclusion of inadequately reported or lower quality studies did not have a significant effect on the results of the synthesis. In this study, we conducted a sensitivity analysis on the basis of reporting criteria with the aims of analysing its impact on the synthesis results and assessing its feasibility. Contrary to some previous studies, our analysis showed that the exclusion of inadequately reported studies had an impact on the results of the thematic synthesis. Initially, we also sought to propose a refinement of reporting criteria based on the literature and our own experiences. In this way, we aimed to facilitate the assessment of reporting criteria and enhance its consistency. However, based on the results of our sensitivity analysis, we opted not to make such a refinement since many publications included in this analysis did not sufficiently report on the methodology. As such, a refinement would not be useful considering that researchers would be unable to assess these (sub-)criteria

DICO Toolkit for Digital Career Stories

Digital Career Stories – Opening new career paths for arts and culture students, or DICO for short, has been a 2-year-long pedagogical development project. Its main objective was to develop innovative narrative and arts- and design-based methods that together form the Digital Career Story methodology introduced in this toolkit. Through the methodology developed, the project aimed to encourage reflection and self-reflection skills in higher education students, along with their digital and creative skills, and to help them build professional identities and design career paths, as well as enhancing their resilience, self-efficacy and self-esteem. The specific target group of the project was students of arts and culture subjects, but the pedagogical methods can just as well be used with other higher education students. The DICO project was the joint effort of a consortium of five European universities: Turku University of Applied Sciences (TUAS), Finland (as the applicant and coordinator of the project), University of Macerata (UniMC), Italy, Staffordshire University (SU), United Kingdom, Moholy-Nagy University of Art and Design (MOME), Hungary, and the Technical University of Dublin (TU Dublin), Ireland. The project was funded by the Erasmus+ programme and lasted from March 2021 to February 2023.The DICO Toolkit contains the project results in the form of a handbook intended for lecturers, counsellors and mentors in Higher Education Institutions (HEIs), and for cultural and creative organisations and professionals. It aims to provide both theoretical frameworks and practical tools for developing art-based methodologies with HEI students in the arts and culture. The book is structured into three sections – Theories and methodologies, Implementing creative methods, and Project evaluation and further resources – and concludes with an Appendix

The "e" in rave : a profile of young ecstasy users and its implication for educators

The use of methylenedioxymethamphetamine (MDMA) or Ecstasy is a phenomenon that has established itself in the widespread Rave culture. Ecstasy use causes not only physical, social and psychological problems in the development of the adolescent but may also influence his concentration and learning abilities. To prevent these problems educators should be well informed regarding current drug use trends and also be capable of assisting adolescents. Research regarding the nature of Ecstasy use and the characteristics of its users is lacking nationally. The increase in use amongst school going adolescents and young adults and the fact that there are side effects and unknown long term effects has made it imperative that educators learn as much as possible about this drug. The purpose of this research is therefore to furnish the educator with accurate information that will enable him to obtain a reference point from which assistance can be offered to the young Ecstasy user.Psychology of EducationM.Ed.(Guidance and Counselling

NASA Tech Briefs, November 2000

Topics covered include: Computer-Aided Design and Engineering; Electronic Components and Circuits; Electronic Systems; Test and Measurement; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Data Acquisition

The Schizophrenic Sign: a dialectic of semiotics and schizophrenia

This thesis posits as its central argument that placing semiotic theory in dialectic with the discourses of and about ‘schizophrenia’ will produce novel insights into both. Simultaneously, this thesis develops a semiological sign system for ‘schizophrenia’, mapping and critiquing its central narratives, organising ethics, aesthetics and thematics, whilst also offering a practical model as exemplar for a semiotic method of cultural, textual, medical, psychological and social critical analysis. In so doing, this thesis presents and develops the concept of ‘schizomimesis’, a term to describe the process by which the discourse and semiological sign system of ‘schizophrenia’ adopts formal qualities that mimetically embody the ‘disease’ symptomatology. The thesis explores this idea, placing different ‘symptoms’ in dialectic with different discourses: thought insertion, influence and the instability of signs in relation to diagnostics and aetiology; ‘psychotic’ speech and so-called thought disorder; distrubances of ipseity and magical thinking in narrative medicine and illness memoirs; hallucinations and delusions of reference in popular cinematic and televisual representations; deictic crises in the person, in the therapeutic process, and across popular culture and society. Throughout, the thesis constructs a de-psychologised and socialised, inter-subjective model of the self, inseparable from the dynamic of indivisible sign relations, and strives to understand ‘schizophrenia’ within this conceptual context. This thesis thereby offers a model of how medical humanities research can contribute evenly to the discplines from which it draws its materials and methodologies. At the same time, it hopes to offer humane and thoughtful observations on the personal, cultural, medical and social disadvantages and difficulties, and highly idiosyncratic experiences, endured by those with lived experience of ‘schizophrenia’