High latency and loss rates in the Internet make it difficult to stream audio and video without introducing a large playback delay. To address these problems, we propose a prefix caching technique whereby a proxy stor...
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High latency and loss rates in the Internet make it difficult to stream audio and video without introducing a large playback delay. To address these problems, we propose a prefix caching technique whereby a proxy stores the initial frames of popular clips. Upon receiving a request for the stream, the proxy initiates transmission to the client and simultaneously requests the remaining frames from the server. In addition to hiding the delay, throughput, and loss effects of a weaker service model between the server and the proxy, this novel yet simple prefix caching technique aids the proxy in performing workahead smoothing into the client playback buffer. By transmitting large frames in advance of each burst, workahead smoothing substantially reduces the peak and variability of the network resource requirements along the path from the proxy to the client. We describe how to construct a smooth transmission schedule, based on the size of the prefix, smoothing, and playback buffers, without increasing client playback delay. Experiments with MPEG traces show how a few megabytes of buffer space at the proxy can substantially reduce the bandwidth requirements of variable-bit-rate video. Drawing on these results, we present guidelines for allocating buffer space for each stream, and how to effectively share buffer and bandwidth resources among multiple clients and streams.
A novel concurrent programming paradigm called hypersequential programming (HSP) is being developed. HSP aims to eliminate all undesirable behaviours from a given application. A fundamental part of that system require...
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A novel concurrent programming paradigm called hypersequential programming (HSP) is being developed. HSP aims to eliminate all undesirable behaviours from a given application. A fundamental part of that system requires the use of test cases for the serialization of a program. Only those test cases found to be correct are used in the final concurrent program. Therefore, HSP relies on all the functionality being included into a program. This is opposite to traditional software engineering practice, which is to ensure that all unwanted behaviours have been removed. We briefly examine the HSP method with reference to test cases and scenarios. We examine a couple of brief examples and discuss the limitations of test cases, with particular respect to HSP. We conclude that finding a method of ensuring the correct set of test cases is used in development is essential to the success of HSP.
The problem of improving the performance and scalability of current monitoring systems, which generally follow a centralised and static management model is considered herein. Several alternative solutions based on Mob...
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The rapid evolution of computer graphics hardware and software has made it easy to construct three dimensional (3D) virtual environments with real-time functionality and more reality. For example, a few years ago most...
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The rapid evolution of computer graphics hardware and software has made it easy to construct three dimensional (3D) virtual environments with real-time functionality and more reality. For example, a few years ago most virtual environments consisted of only static objects such as buildings and mountains. The latest virtual environment has both static and dynamic objects such as moving cars, flying birds and clouds. However, it is not so easy to create such a environment, because dynamic objects such as clouds and water called dynamic natural objects (DNO) change kaleidoscopically from time to time. It takes users more time and effort to create these DNOs and their motions by using animation modeling tools. When creating the shape and motion of DNO in their own brains, the users should be skilled at how to use the modeler. Therefore, we propose a new interactive modeling method to easily make DNOs in the virtual environment. The particle system is one of the most popular methods to represent such objects. This system represents DNOs as a set of points. In our method, we classify a modeling process into three stages: particle generation, particle control and particle animation. Moreover, we classify these stages to some attributes, and we give an attribute to some visualized nodes for modeling rules. Each node has some rules which decide the shape or motion of DNOs. Users create a hierarchical tree to combine these nodes. The particle animation is replayed according to its tree structure. This paper proposes a new interactive modeling method introduced into firework modeling as an example of DNOs and its simulation system, describing processes to create fireworks using this method.
Prediction of problematic software components is an important activity today for many organizations as they manage their legacy systems and the maintenance problems they cause. This means that there is a need for meth...
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Prediction of problematic software components is an important activity today for many organizations as they manage their legacy systems and the maintenance problems they cause. This means that there is a need for methods and models to identify troublesome components. We apply a model for classification of software components as green, yellow and red according to the number of times they required corrective maintenance over successive releases. Further, we apply a principal component and box plot analysis to investigate the causes for the code decay and try to characterize the releases. The case study includes eight releases and 130 software components. The outcome indicates a large number of healthy components as well as a small set of troublesome components requiring extensive repair repeatedly. The analysis characterizes the releases and indicates that it is the relationship between components that causes many of the problems.
While the demand for 3D technologies is growing rapidly, there are some fundamental problems remaining unresolved, such as a way to intuitively create 3D object data in a virtual environment. This paper proposes a new...
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While the demand for 3D technologies is growing rapidly, there are some fundamental problems remaining unresolved, such as a way to intuitively create 3D object data in a virtual environment. This paper proposes a new method for creating 3D objects using bi-manual gestures. To realize an easy-to-use yet powerful modeling capability, we designed a framework defining a dozen primitive hand actions to be used for modeling tasks. Then a 3D modeler was developed to substantiate the framework in a virtual environment, allowing the users to create complex shapes by combining the defined hand actions. We prove that the hand actions described in the framework are essential, and are generally applicable for various modeling tasks, by exemplifying some interesting and practical shapes.
As software systems mature, there is the danger that not only code decays, but software architectures as well. We adapt a reverse architecting technique to defect reports of a series of releases. Relationships among s...
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As software systems mature, there is the danger that not only code decays, but software architectures as well. We adapt a reverse architecting technique to defect reports of a series of releases. Relationships among system components are identified based on whether they are involved in the same defect report, and for how many defect reports this occurs. There are degrees of fault-coupling between components depending on how often two components are involved in a defect fix. After these fault-coupling relationships between components are extracted, they are abstracted to the subsystem level. The resulting fault architecture figures show for each release what its most fault-prone relationships are. Comparing across releases shows whether some relationships between components are repeatedly fault prone, indicating an underlying systemic architecture problem. We illustrate our technique on a large commercial system consisting of over 800 KLOC of C, C++, and microcode.
This paper discusses dynamic load balancing mechanisms for a massively parallel database programming language. Instead of accurate information on object allocation, the proposed approach utilizes approximate informati...
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This paper discusses dynamic load balancing mechanisms for a massively parallel database programming language. Instead of accurate information on object allocation, the proposed approach utilizes approximate information to determine the relocation candidate objects and the destination. The simulation tests reported in this paper confirms the performance improvement achieved by the proposed approach.
Though generally most of chemical processes are complex multivariable systems with strong interactions, PID controllers are used in most cases even nowadays. However, it is well known that the tuning of their paramete...
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