This paper presents research that investigated algorithms for high-precision identification of contextual information in location-aware engineering applications. The primary contribution of the presented work is the d...
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This paper presents research that investigated algorithms for high-precision identification of contextual information in location-aware engineering applications. The primary contribution of the presented work is the design and implementation of a dynamic user-viewpoint tracking scheme in which mobile users' spatial context is defined not only by their position (i.e., location), but also by their three-dimensional head orientation (i.e., line of sight). This allows the identification of objects and artifacts visible in a mobile user's field of view with much higher accuracy than was possible by tracking position alone. For outdoor applications, a georeferencing based algorithm has been developed using the Global Positioning System (GPS) and magnetic orientation tracking devices [5] to track a user's dynamic viewpoint. For indoor applications, this study explored the applicability of wireless technologies, in particular Indoor GPS, for dynamic user position tracking in situations where GPS is unavailable. The objectives of this paper are to describe the details of the three-stage-algorithm that has been designed and implemented, and to demonstrate the extent to which positioning technologies such as GPS and Indoor GPS can be used together with high-precision orientation trackers to accurately interpret the fully-qualified spatial context of a mobile user in challenging environments such as those found on construction sites. The obtained results highlight the potential of using location-aware technologies for rapidly identifying and retrieving contextual information in engineering applications. (C) 2009 Elsevier Ltd. All rights reserved.
An algorithm utilising direct feedbacks of torque and reactive power for the control of a doubly fed induction generator (DFIG) is proposed. Although the algorithm is based on field-oriented control, the algorithm cal...
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An algorithm utilising direct feedbacks of torque and reactive power for the control of a doubly fed induction generator (DFIG) is proposed. Although the algorithm is based on field-oriented control, the algorithm calculates the feedback and feed-forward variables in the stator reference frame to reduce the number of coordinate transformations. Since the algorithm uses a single-loop approach instead of a cascaded loop design, the tuning of the controller is easier and the response time is faster when compared to those of most existing methods. The internal model control (IMC) design method is used in the proposed scheme to formulate the controller parameters. Measures on the possible voltage variations are included to increase the robustness of the system. computer simulation and experimental implementation are reported. The results show that the algorithm can control the torque and reactive power independently. Harmonic distortions generated by the system are not noticeable because of the use of constant switching frequency.
In many network and IT (information technology) systems, users submit loosely defined (or "fuzzy") requests to obtain answers, solutions, or resources. Fuzzy requests are often presented in problem tickets a...
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In many network and IT (information technology) systems, users submit loosely defined (or "fuzzy") requests to obtain answers, solutions, or resources. Fuzzy requests are often presented in problem tickets and processed by an IT service management system. In such a system, problems are typically reported using vague user-generated descriptions of the symptoms (e. g., "my e-mail is not working"). Making use of the reported symptoms, the incident management system is then responsible for identifying the component causing the problem. An accurate and quick diagnosis from the fuzzy symptoms becomes critical for an efficient and timely resolution of the problem. In this paper, we propose a system for automated incident management using historical information (AIM-HI), a framework for autonomous routing of requests in large-scale IT global service delivery. AIM-HI incorporates historical request resolution information and frequency, together with queue bouncing trends to extrapolate algorithms for streamlining and automating the dispatch of requests or work among support groups and IT specialists. The simplicity and scalability of AIM-HI should lead to deployment in actual real operational systems in the future.
Packet-level measurement is now critical to many aspects of broadband networking, for example for guaranteeing service level agreements, facilitating measurement-based admission control algorithms and performing netwo...
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Packet-level measurement is now critical to many aspects of broadband networking, for example for guaranteeing service level agreements, facilitating measurement-based admission control algorithms and performing network tomography. Because it is often impossible to measure all the data passing across a network, the most widely used method of measurement works by injecting probe packets. The probes provide samples of the packet loss and delay, and from these samples the loss and delay performance of the traffic as a whole can be deduced. However, measuring performance like this is prone to errors. Recent work has shown that some of these errors are minimised by using a gamma renewal process as the optimal pattern for the time instants at which to inject probes. This leaves the best rate at which to inject probes as the key unsolved problem, and this is addressed here by using the statistical principles of the design of experiments. The experimental design approach allows one to treat packet-level measurements as numerical experiments that can be designed optimally. Modelling the overflow of buffers as a 2-state Markov chain, the system's likelihood function is deduced, and from this a technique ( using the Fisher information matrix) to determine the upper-bound on the optimal rate of probing is developed. A generalisation of this method accounts for the effect of the probed observations interfering with the experiment. The numerical results focus on VoIP traffic, allowing one to show how this methodology would be used in practice. One application of this is in measurement-based admission control algorithms, where the technique can be used to provide an upper-bound on the rate at which probes should be injected to monitor the loss performance of the target network, prior to making an admit/do not admit decision.
V-variable fractals and superfractals have recently been introduced by Barnsley [Barnsley Michael, Hutchinson John, Stenflo Orjan. A fractal valued random iteration algorithm and fractal hierarchy. Fractals 2005;13(2)...
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V-variable fractals and superfractals have recently been introduced by Barnsley [Barnsley Michael, Hutchinson John, Stenflo Orjan. A fractal valued random iteration algorithm and fractal hierarchy. Fractals 2005;13(2):111-46 [MR2151094 (2006b:28014)]] to the world of mathematics and computer graphics. In this paper, we introduce superior iterates to study the role of contractive and non-contractive operators in relation to superfractals. A modified algorithm along with details of computer implementation is also provided to compute V-variable fractals. A brief discussion about the various aspects of the computed figures indicates usefulness of the study. (C) 2009 Elsevier Ltd. All rights reserved.
Radio resource management algorithms ranging from bearer admission control to semi-persistent and dynamic packet scheduling, fast link adaptation, and transmission control of multi-antenna transmission modes are addre...
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Radio resource management algorithms ranging from bearer admission control to semi-persistent and dynamic packet scheduling, fast link adaptation, and transmission control of multi-antenna transmission modes are addressed in this article for UTRAN long-term evolution. First, a high-level system overview of LTE is given, with special emphasis on the important components related to RRM. The quality of service parameter framework is outlined, as one of the main objectives for the families of RRM algorithms is to maximize system capacity while serving all users according to their minimum QoS constraints. It is demonstrated how the collocation of the RRM algorithms at the base station with easy access to air interface measurements offers opportunities for efficient cross-functional optimization between layers 1, 2, and 3. Examples of performance results for different traffic mixes and antenna transmission schemes are also presented, and the article is concluded with recommendations-on how to operate the various RRM options under different load and traffic conditions.
A novel hash algorithm based on a spatiotemporal chaos is proposed. The original message is first padded with zeros if needed. Then it is divided into a number of blocks each contains 32 bytes. In the hashing process,...
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A novel hash algorithm based on a spatiotemporal chaos is proposed. The original message is first padded with zeros if needed. Then it is divided into a number of blocks each contains 32 bytes. In the hashing process, each block is partitioned into eight 32-bit values and input into the spatiotemporal chaotic system. Then, after iterating the system for four times. the next block is processed by the same way. To enhance the confusion and diffusion effect, the cipher block chaining (CBC) mode is adopted in the algorithm. The hash value is obtained from the final state value of the spatiotemporal chaotic system. Theoretic analyses and numerical simulations both show that the proposed hash algorithm possesses good statistical properties, strong collision resistance and high efficiency, as required by practical keyed hash functions. (C) 2009 Elsevier Ltd. All rights reserved.
I report on a two-particle analysis package in which the algorithmic part is strictly separated from the input data format such that it can be used to analyze data from different experiments. After introducing the ana...
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I report on a two-particle analysis package in which the algorithmic part is strictly separated from the input data format such that it can be used to analyze data from different experiments. After introducing the analysis scheme and briefly discussing some aspects of the implementation I go through a collection of histograms obtained by running the package on data from three heavy-ion experiments.
In this article we discuss the design and implementation of a real-time parallel anomaly detection system. The key idea is to use multiple existing anomaly detection algorithms in parallel on thousands of network traf...
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In this article we discuss the design and implementation of a real-time parallel anomaly detection system. The key idea is to use multiple existing anomaly detection algorithms in parallel on thousands of network traffic subclasses, which not only enables us to detect hidden anomalies but also to increase the accuracy of the system. The main challenge then is the management and aggregation of the vast amount of data generated. We propose a novel aggregation process that uses the internal continuous anomaly metrics used by the algorithms to output a single system-wide anomaly metric. The evaluation on real-world attack traces shows a lower false positive rate and false negative rate than any individual anomaly detection algorithm.
A simple program for constructing a cellular self-reproducing rectangular loop of arbitrary size is developed based on the parallel substitution algorithm (PSA), which provides a spatial model for representing fine-gr...
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A simple program for constructing a cellular self-reproducing rectangular loop of arbitrary size is developed based on the parallel substitution algorithm (PSA), which provides a spatial model for representing fine-grained parallel computations. In order to launch the self-reproduction of a loop of some specified size, one should enter its description into the input tape. The program includes operators for preliminary cleaning the cellular array, which makes it possible to easily change its internal functional structure. Two variants of the program are developed. The first variant constructs a chain of self-reproducing loops of the given size, and the second variant constructs an array of such loops.
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