Architectural design of E1 distributed operating system

Запропоновано архітектуру розподіленої операційної системи, засновану на концепції реплікації розподілених об’єктів. В кожному вузлі, де використовується розподілений об’єкт, розміщується повна або часткова копія його стану. Когерентність копій забезпечується алгоритмами реплікації. При цьому, для кожного об’єкта може використовуватись найбільш ефективний алгоритм доступу, який враховує його семантику. Всі підсистеми ОС спроектовані с урахуванням механізму реплікації, що перетворює Е1 на зручну платформу для розробки надійних розподілених додатків.Предложена архитектура распределенной операционной системы, основанная на концепции репликации распределенных объектов. В каждом узле, где используется распределенный объект, размещается полная или частичная копия его состояния. Когерентность копий обеспечивается алгоритмами репликации. При этом для каждого объекта может применяться наиболее эффективный алгоритм доступа, учитывающий его семантику. Все подсистемы ОС изначально спроектированы с учетом механизма репликации, что делает Е1 удобной платформой для разработки надежных распределенных приложений.This paper presents the distributed operating system architecture based on the concept of replication of distributed objects. A complete or partial copy of distributed object’s state is placed in each node where the object is used. Copy coherence is ensured by replication algorithms. For each object the most efficient access algorithm, taking its semantics into account, can be applied. All E1 subsystems are designed to support replication, which makes E1 a convenient platform for developing reliable distributed applications

Group Performance in Military Scenarios Under Deceptive Conditions

The goal of this research was to investigate how changes in modality (communication type) and external conditioning (warnings of player deception) relate to perceptions of deception and task difficulty and in turn how these perceptions relate to the final group game scores in a cooperative effort with conflicting goals. One hundred and eight participants were grouped into teams of three, given similar instructions but different goals, and asked to play a cooperative game called StrikeCOM that mimics the intelligence gathering needed to develop an air tasking order and subsequent air strike on three military targets. The analysis of the post-game surveys showed support for participants in games using a face-to-face communication method to have lower perceptions of deception and task difficulty when compared to games using real-time plain text chat

Systems support for distributed learning environments

This thesis contends that the growing phenomena of multi-user networked "learning environments" should be treated as distributed interactive systems and that their developers should be aware of the systems and networks issues involved in their construction and maintenance. Such environments are henceforth referred to as distributed learning environments, or DLEs. Three major themes are identified as part of systems support: i) shared resource coherence in DLEs; ii) Quality of Service for the end- users of DLEs; and iii) the need for an integrating framework to develop, deploy and manage DLEs. The thesis reports on several distinct implementations and investigations that are each linked by one or more of those themes. Initially, responsiveness and coherence emerged as potentially conflicting requirements, and although a system was built that successfully resolved this conflict it proved difficult to move from the "clean room" conditions of a research project into a real world learning context. Accordingly, subsequent systems adopted a web-based approach to aid deployment in realistic settings. Indeed, production versions of these systems have been used extensively in credit-bearing modules in several Scottish Universities. Interactive responsiveness then emerged as a major Quality of Service issue in its own right, and motivated a series of investigations into the sources of delay, as experienced by end users of web-oriented distributed learning environments. Investigations into this issue provided insight into the nature of web-oriented interactive distributed learning and highlighted the need to be QoS-aware. As the volume and the range of usage of distributed learning applications increased the need for an integrating framework emerged. This required identifying and supporting a wide variety of educational resource types and also the key roles occupied by users of the system, such as tutors, students, supervisors, service providers, administrators, examiners. The thesis reports on the approaches taken and lessons learned from researching, designing and implementing systems which support distributed learning. As such, it constitutes a documented body of work that can inform the future design and deployment of distributed learning environments

Virtually-Synchronous Communication Based on a Weak Failure Suspector

Failure detectors (or, more accurately Failure Suspectors -- FS) appear to be a fundamental service upon which to build fault-tolerant, distributed applications. This paper shows that a FS with very weak semantics (i.e. that delivers failure and recovery information in no specific order) suffices to implement virtually-synchronous communication (VSC) in an asynchronous system subject to process crash failures and network partitions. The VSC paradigm is particularly useful in asynchronous systems and greatly simplifies building fault-tolerant applications that mask failures by replicating processes. We suggest a three-component architecture to implement virtuallysynchronous communication : 1) at the lowest level, the FS component; on top of it, 2a) a component that defines new views, and 2b) a component that reliably multicasts messages within a view. 1 Introduction There have recently been several papers about membership services in asynchronous systems [2, 12, 16, 17, 18]. A member..

Review of Particle Physics

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,062 new measurements from 721 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 117 reviews are many that are new or heavily revised, including new reviews on Pentaquarks and Inflation. The complete Review is published online in a journal and on the website of the Particle Data Group (http://pdg.lbl.gov). The printed PDG Book contains the Summary Tables and all review articles but no longer includes the detailed tables from the Particle Listings. A Booklet with the Summary Tables and abbreviated versions of some of the review articles is also available.The publication of the Review of Particle Physics is supported by the Director, Office of Science, Office of High Energy Physics of the U.S. Department of Energy under Contract No. DE–AC02–05CH11231; by the European Laboratory for Particle Physics (CERN); by an implementing arrangement between the governments of Japan (MEXT: Ministry of Education, Culture, Sports, Science and Technology) and the United States (DOE) on cooperative research and development; by the Institute of High Energy Physics, Chinese Academy of Sciences; and by the Italian National Institute of Nuclear Physics (INFN).The authors are grateful to Vincent Vennin for his careful reading of this manuscript and preparing Fig. 23.3 for this review. The work of J.E. was supported in part by the London Centre for Terauniverse Studies (LCTS), using funding from the European Research Council via the Advanced Investigator Grant 267352 and from the UK STFC via the research grant ST/L000326/1. The work of D.W. was supported in part by the UK STFC research grant ST/K00090X/1

Review of particle physics

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,062 new measurements from 721 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 117 reviews are many that are new or heavily revised, including those on Pentaquarks and Inflation. The complete Review is published online in a journal and on the website of the Particle Data Group (http://pdg.lbl.gov). The printed PDG Book contains the Summary Tables and all review articles but no longer includes the detailed tables from the Particle Listings. A Booklet with the Summary Tables and abbreviated versions of some of the review articles is also available