12,971 research outputs found
Execution replay and debugging
As most parallel and distributed programs are internally non-deterministic --
consecutive runs with the same input might result in a different program flow
-- vanilla cyclic debugging techniques as such are useless. In order to use
cyclic debugging tools, we need a tool that records information about an
execution so that it can be replayed for debugging. Because recording
information interferes with the execution, we must limit the amount of
information and keep the processing of the information fast. This paper
contains a survey of existing execution replay techniques and tools.Comment: In M. Ducasse (ed), proceedings of the Fourth International Workshop
on Automated Debugging (AADebug 2000), August 2000, Munich. cs.SE/001003
Tourism and the smartphone app: capabilities, emerging practice and scope in the travel domain.
Based on its advanced computing capabilities and ubiquity, the smartphone has rapidly been adopted as a tourism travel tool.With a growing number of users and a wide varietyof applications emerging, the smartphone is fundamentally altering our current use and understanding of the transport network and tourism travel. Based on a review of smartphone apps, this article evaluates the current functionalities used in the domestic tourism travel domain and highlights where the next major developments lie. Then, at a more conceptual level, the article analyses how the smartphone mediates tourism travel and the role it might play in more collaborative and dynamic travel decisions to facilitate sustainable travel. Some emerging research challenges are discussed
Context of Production Control in Construction
It is commonly accepted that production control systems should correspond to the context within which they are operating, i.e. the production situation. However, rarely is this context indicated or made explicit; for example, the boundary conditions or the range of validity of a particular production control method. Thus, it is the aim of this paper to analyze how the production context could more sys- tematically be taken into account when determining which production control system to use. Whilst it is acknowledged that contextual issues can be approached in a variety of ways, this is dependent on the perspective being considered (e.g. from a management hierarchy perspective, or a process stage perspective). This investigation looks at context from a process stage perspective and firstly considers the major production control approaches (such as CPM, Line-of-Balance, Last Planner System and Critical Chain) to determine their range of validity. Secondly, we endeavour to identify a typology of production control situations (ideal types), together with a suggestion for production control in each case. Finally, we attempt to deconstruct production control into its constituent elements and evaluate the alternative suggestions at this elemental level in relation to their contextual assumptions. In the paper, all three approaches are discussed and illustrated, based on prior literature and field observations
Overregulation of Health Care: Musings on Disruptive Innovation Theory
Disruptive innovation theory provides one lens through which to describe how regulations may stifle innovation and increase costs. Basing their discussion on this theory, Curtis and Schulman consider some of the effects that regulatory controls may have on innovation in the health sector
Overregulation of Health Care: Musings on Disruptive Innovation Theory
Disruptive innovation theory provides one lens through which to describe how regulations may stifle innovation and increase costs. Basing their discussion on this theory, Curtis and Schulman consider some of the effects that regulatory controls may have on innovation in the health sector
The Use of Contact Heat Generators of the New Generation for Heat Production
We substantiated the need for searching for, and realization of, fundamentally new approaches, using more efficient physical, heat-mass-exchanging and aerodynamic processes, which will make it possible to improve energy effectiveness and ecological cleanliness of heat generation in the systems for individual and decentralized heat supply.For the heat supply to large cities and industrial regions, we examined the advantages of using highly efficient contact heat-generators of different types, which include compactness due to low metal consumption and, as a result, attractive price.It is proposed to use a heat-generator of contact type of the new generation, with the aid of which it was possible to solve a set of problems on the qualitative combustion of fuel and effective heat exchange of gases with the heated water. The use of tubular technology for the combustion of gas is its special feature. Due to it, quality heat exchanging characteristics are provided.In view of further studies, we presented the relevance of creating heat-generators with the use of highly effective hydrogen technologies, which will make it possible to devise the new energy paradigm of heat supply for residential areas and industrial zones through the possibility of accumulation of electrical energy and accumulation of hydrogen
Cloud-efficient modelling and simulation of magnetic nano materials
Scientific simulations are rarely attempted in a cloud due to the substantial
performance costs of virtualization. Considerable communication overheads,
intolerable latencies, and inefficient hardware emulation are the main reasons why
this emerging technology has not been fully exploited. On the other hand, the
progress of computing infrastructure nowadays is strongly dependent on
perspective storage medium development, where efficient micromagnetic
simulations play a vital role in future memory design.
This thesis addresses both these topics by merging micromagnetic simulations
with the latest OpenStack cloud implementation while providing a time and costeffective alternative to expensive computing centers.
However, many challenges have to be addressed before a high-performance cloud
platform emerges as a solution for problems in micromagnetic research
communities. First, the best solver candidate has to be selected and further
improved, particularly in the parallelization and process communication domain.
Second, a 3-level cloud communication hierarchy needs to be recognized and
each segment adequately addressed. The required steps include breaking the VMisolation for the hostâs shared memory activation, cloud network-stack tuning,
optimization, and efficient communication hardware integration.
The project work concludes with practical measurements and confirmation of
successfully implemented simulation into an open-source cloud environment. It is
achieved that the renewed Magpar solver runs for the first time in the OpenStack
cloud by using ivshmem for shared memory communication. Also, extensive
measurements proved the effectiveness of our solutions, yielding from sixty
percent to over ten times better results than those achieved in the standard cloud.Aufgrund der erheblichen Leistungskosten der Virtualisierung werden
wissenschaftliche Simulationen in einer Cloud selten versucht. BetrÀchtlicher
Kommunikationsaufwand, erhebliche Latenzen und ineffiziente
Hardwareemulation sind die HauptgrĂŒnde, warum diese aufkommende
Technologie nicht vollstÀndig genutzt wurde. Andererseits hÀngt der Fortschritt der
Computertechnologie heutzutage stark von der Entwicklung perspektivischer
Speichermedien ab, bei denen effiziente mikromagnetische Simulationen eine
wichtige Rolle fĂŒr die zukĂŒnftige Speichertechnologie spielen.
Diese Arbeit befasst sich mit diesen beiden Themen, indem mikromagnetische
Simulationen mit der neuesten OpenStack Cloud-Implementierung
zusammengefĂŒhrt werden, um eine zeit- und kostengĂŒnstige Alternative zu teuren
Rechenzentren bereitzustellen.
Viele Herausforderungen mĂŒssen jedoch angegangen werden, bevor eine
leistungsstarke Cloud-Plattform als Lösung fĂŒr Probleme in mikromagnetischen
Forschungsgemeinschaften entsteht. ZunĂ€chst muss der beste Kandidat fĂŒr die
Lösung ausgewÀhlt und weiter verbessert werden, insbesondere im Bereich der
Parallelisierung und Prozesskommunikation. Zweitens muss eine 3-stufige CloudKommunikationshierarchie erkannt und jedes Segment angemessen adressiert
werden. Die erforderlichen Schritte umfassen das Aufheben der VM-Isolation, um
den gemeinsam genutzten Speicher zwischen Cloud-Instanzen zu aktivieren, die
Optimierung des Cloud-Netzwerkstapels und die effiziente Integration von
Kommunikationshardware.
Die praktische Arbeit endet mit Messungen und der BestÀtigung einer erfolgreich
implementierten Simulation in einer Open-Source Cloud-Umgebung. Als Ergebnis
haben wir erreicht, dass der neu erstellte Magpar-Solver zum ersten Mal in der
OpenStack Cloud ausgefĂŒhrt wird, indem ivshmem fĂŒr die Shared-Memory
Kommunikation verwendet wird. Umfangreiche Messungen haben auch die
Wirksamkeit unserer Lösungen bewiesen und von sechzig Prozent bis zu zehnmal
besseren Ergebnissen als in der Standard Cloud gefĂŒhrt
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