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81.
Karun Rawat Fadhel M. Ghannouchi Meenakshi Rawat Mohammad S. Hashmi 《国际射频与微波计算机辅助工程杂志》2011,21(3):325-335
This article proposes an analytical design methodology for dual‐band hybrid couplers and baluns structures for any arbitrary frequency ratio using a stub‐loaded transmission line. An analysis of changing the impedance behavior of the stub, is carried out for the two bands of operation, which along with a dispersive analysis, emphasizes certain conditions where the existing methodology is not applicable. In addition, an extra degree of freedom has been included to increase the solutions for a given frequency ratio, thus providing greater flexibility and feasibility of the proposed structure. The design methodology is experimentally validated with the design and fabrication of dual‐band branch‐line and rat‐race couplers for various commercial frequency bands. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011. 相似文献
82.
Sudip Misra Author Vitae Author Vitae Mohammad S. Obaidat Author Vitae Pushkar Gupta Author Vitae Author Vitae Prayag Narula Author Vitae 《Journal of Systems and Software》2010,83(11):2188-2199
Primitive routing protocols for ad-hoc networks are “power hungry” and can therefore consume considerable amount of the limited amount of battery power resident in the nodes. Thus, routing in ad-hoc networks is very much energy-constrained. Continuous drainage of energy degrades battery performance as well. If a battery is allowed to intermittently remain in an idle state, it recovers some of its lost charge due to the charge recovery effect, which, in turn, results in prolonged battery life.In this paper, we use the ideas of naturally occurring ants’ foraging behavior (Dorigo and Stuetzle, 2004) [1] and based on those ideas, we design an energy-aware routing protocol, which not only incorporates the effect of power consumption in routing a packet, but also exploits the multi-path transmission properties of ant swarms and, hence, increases the battery life of a node. The efficiency of the protocol with respect to some of the existing ones has been established through simulations. It has been observed that the energy consumed in the network, the energy per packet in the case of EAAR are 60% less compared to MMBCR and the packets lost is only around 12% of what we have in AODV, in mobility scenarios. 相似文献
83.
Mohammad Shorfuzzaman Peter Graham Rasit Eskicioglu 《The Journal of supercomputing》2010,51(3):374-392
Data grids support access to widely distributed storage for large numbers of users accessing potentially many large files.
Efficient access is hindered by the high latency of the Internet. To improve access time, replication at nearby sites may
be used. Replication also provides high availability, decreased bandwidth use, enhanced fault tolerance, and improved scalability.
Resource availability, network latency, and user requests in a grid environment may vary with time. Any replica placement
strategy must be able to adapt to such dynamic behavior. In this paper, we describe a new dynamic replica placement algorithm,
Popularity Based Replica Placement (PBRP), for hierarchical data grids which is guided by file “popularity”. Our goal is to
place replicas close to clients to reduce data access time while still using network and storage resources efficiently. The
effectiveness of PBRP depends on the selection of a threshold value related to file popularity. We also present Adaptive-PBRP
(APBRP) that determines this threshold dynamically based on data request arrival rates. We evaluate both algorithms using
simulation. Results for a range of data access patterns show that our algorithms can shorten job execution time significantly
and reduce bandwidth consumption compared to other dynamic replication methods. 相似文献
84.
Oliver Schreer Ingo Feldmann Isabel Alonso Mediavilla Pedro Concejero Abdul H. Sadka Mohammad Rafiq Swash Sergio Benini Riccardo Leonardi Tijana Janjusevic Ebroul Izquierdo 《Multimedia Tools and Applications》2010,48(1):23-49
Multimedia analysis and reuse of raw un-edited audio visual content known as rushes is gaining acceptance by a large number
of research labs and companies. A set of research projects are considering multimedia indexing, annotation, search and retrieval
in the context of European funded research, but only the FP6 project RUSHES is focusing on automatic semantic annotation,
indexing and retrieval of raw and un-edited audio-visual content. Even professional content creators and providers as well
as home-users are dealing with this type of content and therefore novel technologies for semantic search and retrieval are
required. In this paper, we present a summary of the most relevant achievements of the RUSHES project, focusing on specific
approaches for automatic annotation as well as the main features of the final RUSHES search engine. 相似文献
85.
Fuzzy grey relational analysis for software effort estimation 总被引:1,自引:1,他引:0
Accurate and credible software effort estimation is a challenge for academic research and software industry. From many software
effort estimation models in existence, Estimation by Analogy (EA) is still one of the preferred techniques by software engineering
practitioners because it mimics the human problem solving approach. Accuracy of such a model depends on the characteristics
of the dataset, which is subject to considerable uncertainty. The inherent uncertainty in software attribute measurement has
significant impact on estimation accuracy because these attributes are measured based on human judgment and are often vague
and imprecise. To overcome this challenge we propose a new formal EA model based on the integration of Fuzzy set theory with
Grey Relational Analysis (GRA). Fuzzy set theory is employed to reduce uncertainty in distance measure between two tuples
at the k
th
continuous feature ( | ( xo(k) - xi(k) | ) \left( {\left| {\left( {{x_o}(k) - {x_i}(k)} \right.} \right|} \right) .GRA is a problem solving method that is used to assess the similarity between two tuples with M features. Since some of these features are not necessary to be continuous and may have nominal and ordinal scale type, aggregating
different forms of similarity measures will increase uncertainty in the similarity degree. Thus the GRA is mainly used to
reduce uncertainty in the distance measure between two software projects for both continuous and categorical features. Both
techniques are suitable when relationship between effort and other effort drivers is complex. Experimental results showed
that using integration of GRA with FL produced credible estimates when compared with the results obtained using Case-Based
Reasoning, Multiple Linear Regression and Artificial Neural Networks methods. 相似文献
86.
The probabilistic visual tracking methods using color histograms have been proven to be robust to target model variations and background illumination changes as shown by the recent research. However, the required computational cost is high due to intensive image data processing. The embedded solution of such algorithms become challenging due to high computational power demand and algorithm complexity. This paper presents a hardware/software co-design architecture for implementation of the well-known kernel based mean shift tracking algorithm. The design uses color histogram of the target as tracking feature. The target is searched in the consecutive images by maximizing the statistical match of the color distributions. The target localization is based on gradient based iterative search instead of exhaustive search which makes the system capable of achieving frame rate up to hundreds of frames per second while tracking multiple targets. The design, which is fully standalone, is implemented on a low-cost medium-size field programmable gate array (FPGA) device. The hardware cost of the design is compared with some other tracking systems. The performance of the system in terms of speed is evaluated and compared with the software based implementation. It is expected that the proposed solution will find its utility in applications like embedded automatic video surveillance systems. 相似文献
87.
Arya Aghili Ashtiani Mohammad Bagher Menhaj 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2010,14(6):545-557
In this paper, we study and formulate a BP learning algorithm for fuzzy relational neural networks based on smooth fuzzy norms
for functions approximation. To elaborate the model behavior more, we have used different fuzzy norms led to a new pair of
fuzzy norms. An important practical case in fuzzy relational equations (FREs) is the identification problem which is studied
in this work. In this work we employ a neuro-based approach to numerically solve the set of FREs and focus on generalized
neurons that use smooth s-norms and t-norms as fuzzy compositional operators. 相似文献
88.
Hossam Mohammad Khalil Mohammad El-Bardini 《Expert systems with applications》2011,38(11):14249-14256
The performance of a model-based control system depends strongly on the accuracy of the process model used. LS-SVM is a powerful method for modeling nonlinear systems. The main objective of this paper is to implement a conventional controller based on LS-SVM model for hydraulic motor. An off-line model is first identified based on LS-SVM, then via simulation tests the parameters of the discrete PI-Controller and its velocity-form are obtained then the controller parameters are applied experimentally for the hydraulic motor as a speed controller. The system performance has been evaluated; results show good performance over a wide range of operating conditions and load disturbances. 相似文献
89.
A predictive functional controller based on ARMarkov model structure has been designed to control welding current and arc voltage in a GMAW process. The closed loop system performance is investigated through computer simulations and is compared by those achieved from implementing two commonly used controllers i.e. PI and feedback linearization based PID. The local stability of the closed loop system is analyzed in the presence of uncertainties in the linearized model of the process as well as the control parameters. Finally it is shown that the proposed controller performs like a PI controller along with a pre-filter compensator. 相似文献
90.
In this paper, a new algorithm for solving constrained nonlinear programming problems is presented. The basis of our proposed algorithm is none other than the necessary and sufficient conditions that one deals within a discrete constrained local optimum in the context of the discrete Lagrange multipliers theory. We adopt a revised particle swarm optimization algorithm and extend it toward solving nonlinear programming problems with continuous decision variables. To measure the merits of our algorithm, we provide numerical experiments for several renowned benchmark problems and compare the outcome against the best results reported in the literature. The empirical assessments demonstrate that our algorithm is efficient and robust. 相似文献