Carbon-9 beams represent one of the possible alternatives (presently under consideration and investigation) to conventional 12C beams for heavy-ion cancer treatment. Interest in this exotic isotope stems from the expe...
In this short paper, we review the TrustNeighborhoods system for 2D and 3D visualization of trust relationships on the Internet for novice and intermediate-level users. Intended to convey a tangible mental model of se...
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This paper introduces a pattern for almost compositional functions over recursive data types, and over families of mutually recursive data types. Here "almost compositional" means that for a number of the co...
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Inter-object occlusion is inherent to 3D environments and is one of the challenges of using 3D instead of 2D computer graphics for information visualization. In this paper, we examine this occlusion problem by buildin...
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ISBN:
(纸本)1595933530
Inter-object occlusion is inherent to 3D environments and is one of the challenges of using 3D instead of 2D computer graphics for information visualization. In this paper, we examine this occlusion problem by building a theoretical framework of its causes and components. As a result of this analysis, we present an interaction technique for view projection animation that reduces inter-object occlusion in 3D environments without modifying the geometrical properties of the objects themselves. The technique provides smooth on-demand animation between parallel and perspective projection modes as well as online manipulation of view parameters, allowing the user to quickly and easily adapt the view to avoid occlusion. A user study indicates that the technique significantly improves object discovery over normal perspective views. We have also implemented a prototype of the technique in the Blender 3D modeller. Copyright 2006 ACM.
This paper presents an empirical quality assessment of use cases with the purpose to provide defect data from industry. In the assessment, twelve criteria, based on earlier research, were applied to 43 use cases from ...
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ISBN:
(纸本)1595932186
This paper presents an empirical quality assessment of use cases with the purpose to provide defect data from industry. In the assessment, twelve criteria, based on earlier research, were applied to 43 use cases from Volvo Car Corporation developed according to current practice. The collected defect data were statistically analyzed to determine significant intensity differences and to establish a partial order between the defects types based on their intensity. In addition, a qualitative assessment was made to assess the effect of remaining defects on the established order. The study shows that the defect types with the highest defect intensity are Missing element and Incorrect linguistics. Further, the established defect order is the basis for a comparison between the criteria used and earlier research on guidelines and checklists for use case authoring, resulting in improvement propositions. Copyright 2006 ACM.
The problem of information flow in multithreaded programs remains an important open challenge. Existing approaches to specifying and enforcing information-flow security often suffer from over-restrictiveness, relying ...
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The traditional single-core processors are being replaced by chip multiprocessors (CMPs) where several processor cores are integrated on a single chip. While this is beneficial for multithreaded applications and multi...
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The traditional single-core processors are being replaced by chip multiprocessors (CMPs) where several processor cores are integrated on a single chip. While this is beneficial for multithreaded applications and multiprogrammed workloads, CMPs do not provide performance improvements for single-threaded applications. Thread-level speculation (TLS) has been proposed as a way to improve single-thread performance on such systems. TLS is a technique where programs are aggressively parallelized at run-time - threads speculate on data and control dependences but have to be squashed and start over in case of a dependence violation. Unfortunately, various sources of overhead create a major performance problem for TLS. This thesis quantifies the impact of overheads on the performance of TLS systems, and suggests remedies in the form of a number of overhead-reduction techniques. These techniques target run-time parallelization that do not require recompilation of sequential binaries. The main source of parallelism investigated in this work is module continuations, i.e. functions or methods are run in parallel with the code following the call instruction. Loops is another source. Run-length prediction, a technique aimed at reducing the amount of short threads, is introduced. An accurate predictor that avoids short threads, or dynamically unrolls loops to increase thread lengths, is shown to improve speedup for most of the bench-marks applications. Another novel technique is misspeculation prediction, which can remove most of the TLS overhead by reducing the number of misspeculations. The interaction between thread-level parallelism and instruction-level parallelism is studied - in many cases, both sources can be exploited for additional performance gains, but in some cases there is a trade-off. Communication overhead and memory-level parallelism are found to play an important role. For some applications, prefetching from threads that are squashed contributes more to speedup tha
Certain problems associated with reliable digital wireless communication over a frequency-flat slow Rayleigh fading channel are treated, when the transmitted signal is modulated using continuous phase modulation (CPM)...
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Certain problems associated with reliable digital wireless communication over a frequency-flat slow Rayleigh fading channel are treated, when the transmitted signal is modulated using continuous phase modulation (CPM) due to the desirable properties of CPM. The primary focus of attention is on detection strategies, and the thesis proposes iterative detection algorithms for CPM signals transmitted over frequency-flat slow Rayleigh fading channels. First, detection of space-time coded CPM (STC-CPM) signals is investigated, and a symbol-by-symbol iterative detector with an optimum front-end is derived. According to numerical examples, the proposed detector performs around 1 dB away from the no-fading scenario suggesting its effectiveness to mitigate adverse effects of fading. The detection algorithms are later extended to multiuser CPM communication, where the transmitter multiplexes several users into the same frequency band. The proposed multiuser detector performs very close to a single user detector when each user has more than one receiving antenna. Also, when the ratio between the number of users and the number of receiving antennas decreases, the performance difference between the single user system and the multiuser system becomes small. The study is further extended to propose new detection procedures for serially concatenated CPM (SCCPM) when the receiver has no information of the channel state information (CSI). The proposed receiver adds a separate low-complexity module to the iterative SCCPM detector, to systematically handle the detection process using the sum-product algorithm (SPA) running on a factor graph (FG). Two algorithms based on SPA are proposed, for Wiener phase noise (PN), and flat-fading.
Currently there exist dozens of web controller frameworks that are incompatible, but at the same time have large portions of overlapping functionality that is implemented over and over again. Web programmers are facin...
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ISBN:
(纸本)3939352055
Currently there exist dozens of web controller frameworks that are incompatible, but at the same time have large portions of overlapping functionality that is implemented over and over again. Web programmers are facing limitations on code reuse, application and framework integration, extensibility, expressiveness of programming model and productivity. In this paper we propose a minimalistic component model Aranea that is aimed at constructing and integrating server-side web controller frameworks in Java. It allows assembling most of available web programming models out of reusable components and patterns. We also show how to integrate different existing frameworks using Aranea as a common protocol. In its default configuration Aranea supports both developing sophisticated user interfaces using stateful components and nested processes as well as high-performance stateless components. We propose to use this model as a platform for framework development, integration and research. This would allow combining different ideas and avoid reimplementing the same features repeatedly. An open source implementation of Aranea framework together with reusable controls, such as input forms and data lists, and a rendering engine are ready for real-life applications. Copyright 2006 ACM.
The use of Radio Frequency Identification systems (RFID) is growing rapidly. Today, mostly "passive" RFID systems are used because no onboard energy source is needed on the transponders. However, "activ...
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