Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 19 of 19 for “"Virtual Time"”.
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Virtual time synchronization in distributed database systems
Distributed systems synchronized by Virtual Time have been topics of recent interest. Virtual Time follows an optimistic philosophy relying on rollback for synchronization instead of abortion or blocKing Although many applications have been suggested as candidates for Virtual Time, few were …
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Controlled virtual time advancement in conjoined emulation and network simulation
… such hybrid systems are generally not scalable. Virtual time systems attempt to provide a feasible solution by defining and controlling a virtual clock to alter an experiment’s notion of time. Previous works have motivated and explored the benefits of virtual time systems in improving the …
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TimeKeeper: a lightweight and scalable virtual time system for the Linux Kernel
The ability to embed certain processes in virtual time is very useful to the Linux Kernel. Each process may be directed to advance in virtual time either more quickly or more slowly than actual (real) time. This allows interactions between processes and physical devices to be artificially scaled. …
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Detection, classification and localization of seabed objects with a virtual time reversal mirror
… objects in shallow water environments using a time reversal approach in a bistatic configuration. The waveguide is insonified at low frequency ('kHz) with an omnidirectional source and the resulting scattered field is sampled by a receiving array towed behind an Autonomous Underwater Vehicle …
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Effect of an exercise based intervention on Virtual Time to Contact and Seated Instability Index as a function of seated postural control
… was assessed using force platform metrics. Virtual Time to Contact (VTC) and Seated Instability Index (SII) were calculated. There were no differences in mean VTC or SII between groups. Additional testing revealed significant percent change from zero was found in VTC (p=0.007) as a result of …
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'Having a mentor made this journey easier' : an exploration of a formal, virtual, time-bound and paid-for mentoring programme in a dispersed third-sector organisation
… approach. This single case study of a formal, virtual, time-bound and paid-for mentoring scheme in a dispersed, third-sector organisation examines how mentoring can be developmental under these particular circumstances. A review of the literature was carried out within three sectors: workplace, …
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Temporal synchronization of emulated and simulated models for assessment of networked systems
… simulated components is synchronized to a shared virtual clock. The practical utility of a co-simulation platform depends on some crucial factors. Precise control over the scheduling order of emulated processes is required to make the behavior of the co-simulation independent of the CPU resources …
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Dynamic strategies of human postural control
… by means of computer graphics. The notion that virtual time-to-contact, which specifies the spatio-temporal proximity of the pressure center to the stability boundary is one of the controllable parameters for postural dynamics, was examined while subjects performed a variety of upright postural …
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Thread Scheduling in Embedded Runtime Systems
… on the resource-constrained embedded run-time system. The current state-of-art priority-based scheduler heavily relies on developers deliberate tuning of the programs to achieve good performance or even correct behavior. A simple mistake in setting the scheduler parameters can lead to …
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A study into concurrent advancement of simulation and emulation using composite synchronization.
… of simulation and emulation is done in virtual time thanks to TimeKeeper, a recent open source tool that brings Linux processes to virtual time. Previous work involved integration of TimeKeeper with simulators such as CORE and ns-3. The purpose of this thesis is to explore and analyze …
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Threaded WARPED : An Optimistic Parallel Discrete Event Simulator for Cluster of Multi-Core Machines
… PDES simulation kernel that implements the Time Warp paradigm. It was originally designed for efficient executionon single-core Beowulf Clusters. The work of this thesis extends the WARPED kernel to contain parallelthreaded execution on each node as well as parallelism between the nodes of …
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Network-simulation-based evaluation of smart grid applications
… testbed using both parallel simulation and virtual- machine-based, virtual-time-embedded emulation to provide both functional and temporal fidelity for running large-scale networking experiments, so that technologies can be appropriately evaluated with modeling and simulation methodologies …
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Adaptive techniques for scalable optimistic parallel discrete event simulation
… DES simulations do not rely on a global time step and simulated entities are only updated at discrete points in virtual time at which events occur. The particular DES simulation engine handles simulation logic and event scheduling, while the particular models written by domain experts …
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Efficient Message Logging to Support Process Replicas in a Volunteer Computing Environment
… same logical program state at different clock times, communicated data objects must be logged to ensure the replicas of a logical process receive identical communication data streams. Logging to support redundancy can be the source of a significant overhead in time and storage. In this thesis …
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An Adaptive Time Window Algorithm for Large Scale Network Emulation
… models like queues and Petri-nets. The Adaptive Time Window algorithm is a bounded optimistic parallel simulation algorithm with the capability to change the degree of optimism with changes in the degree of causality in the network. The optimism at any instant is bounded by the amount of virtual …
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The Distributed Open Network Emulator: Applying Relativistic Time
… programming model based on C, and a scaled real-time method for distributed synchronization. One of the primary challenges in the development of DONE was in reconciling the opposing requirements of emulation and simulation. Emulated code directly executes in real-time which progresses …
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Packet voice/data in local broadcast networks
… performance measures of average packet time delay and throughput cannot adequately characterise protocol performance for packet voice. Rather, the percentage of bits delivered within a given time bound becomes the relevant performance measure. Performance evaluation of the protocols has …
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Collaborative Interaction in Virtual Environments
Collaborative virtual environments (CVEs) extend existing virtual environment (VE) technology to enable it to run over a network (e.g. the Internet), and introduce mechanisms that allow multiple people to co-exist, be aware of each other’s presence (e.g. through avatars) and communicate. CVEs are …
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A novel approach for large-scale flood risk assessments
… is introduced, where the synthetic discharge time series is used as input into flood impact models and flood risk is directly derived from the resulting synthetic damage time series. The bottleneck at this scale is the hydrodynamic simu-lation. To find suitable hydrodynamic approaches for the …