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Network Applications (network + application)
Selected AbstractsArtificial neural networks for estimating soil hydraulic parameters from dynamic flow experimentsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2005G. H. Schmitz Summary Inverse methods are often used for estimating soil hydraulic parameters from experiments on flow of water through soil. We propose here an alternative method using neural networks. We teach a problem-adapted network of radial basis functions (RBF) the relationship between soil parameters and transient flow patterns using a numerical flow model. The trained RBF network accurately identifies soil parameters from flow patterns not contained in the training scenarios. A comparison with the inverse method (Annealing-Simplex) reveals a similarly good prediction by both approaches for randomly perturbed data and data from the real world. Nonetheless, the inverse method showed dependency on initial parameter estimates not required by the RBF network. Training demands moderately more computation and manpower than the inverse technique, but the absolutely stable and simple network application requires negligible resources. Thus, for individual applications, the network approach is slightly surpassed by the Annealing-Simplex method. However, the RBF network has to be trained only once and, subsequently, it can be applied easily and without effort upon any number of laboratory experiments with standardized experimental setups. [source] Cross-validation of neural network applications for automatic new topic identificationJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 3 2008H. Cenk Ozmutlu The purpose of this study is to provide results from experiments designed to investigate the cross-validation of an artificial neural network application to automatically identify topic changes in Web search engine user sessions by using data logs of different Web search engines for training and testing the neural network. Sample data logs from the FAST and Excite search engines are used in this study. The results of the study show that identification of topic shifts and continuations on a particular Web search engine user session can be achieved with neural networks that are trained on a different Web search engine data log. Although FAST and Excite search engine users differ with respect to some user characteristics (e.g., number of queries per session, number of topics per session), the results of this study demonstrate that both search engine users display similar characteristics as they shift from one topic to another during a single search session. The key finding of this study is that a neural network that is trained on a selected data log could be universal; that is, it can be applicable on all Web search engine transaction logs regardless of the source of the training data log. [source] Error resilient data transport in sensor network applications: A generic perspective,INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 2 2009Rachit Agarwal Abstract The error recovery problem in wireless sensor networks is studied from a generic resource-constrained energy-optimization perspective. To characterize the features of error recovery schemes that suit the majority of applications, an energy model is developed and inferences are drawn based on a suitable performance metric. For applications that require error control coding, an efficient scheme is proposed based on an interesting observation related to shortened Reed,Solomon (RS) codes for packet reliability. It is shown that multiple instances (,) of RS codes defined on a smaller alphabet combined with interleaving results in smaller resource usage, while the performance exceeds the benefits of a shortened RS code defined over a larger alphabet. In particular, the proposed scheme can have an error correction capability of up to , times larger than that of the conventional RS scheme without changing the rate of the code with much lower power, timing and memory requirements. Implementation results show that such a scheme is 43% more power efficient compared with the RS scheme with the same code rate. Besides, such an approach results in 46% faster computations and 53% reduction in memory requirements. Copyright © 2008 John Wiley & Sons, Ltd. [source] Online end-to-end quality of service monitoring for service level agreement managementINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2008Xiaoyuan Ta Abstract A major challenge in network and service level agreement (SLA) management is to provide Quality of Service (QoS) demanded by heterogeneous network applications. Online QoS monitoring plays an important role in the process by providing objective measurements that can be used for improving network design, troubleshooting and management. Online QoS monitoring becomes increasingly difficult and complex due to the rapid expansion of the Internet and the dramatic increase in the speed of network. Sampling techniques have been explored as a means to reduce the difficulty and complexity of measurement. In this paper, we investigate several major sampling techniques, i.e. systematic sampling, simple random sampling and stratified sampling. Performance analysis is conducted on these techniques. It is shown that stratified sampling with optimum allocation has the best performance. However, stratified sampling with optimum allocation requires additional statistics usually not available for real-time applications. An adaptive stratified sampling algorithm is proposed to solve the problem. Both theoretical analysis and simulation show that the proposed adaptive stratified sampling algorithm outperforms other sampling techniques and achieves a performance comparable to stratified sampling with optimum allocation. A QoS monitoring software using the aforementioned sampling techniques is designed and tested in various real networks. Copyright © 2007 John Wiley & Sons, Ltd. [source] Energy-efficient target detection in sensor networks using line proxiesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2008Jangwon Lee Abstract One of the fundamental and important operations in sensor networks is sink,source matching, i.e. target detection. Target detection is about how a sink finds the location of source nodes observing the event of interest (i.e. target activity). This operation is very important in many sensor network applications such as military battlefield and environment habitats. The mobility of both targets and sinks brings significant challenge to target detection in sensor networks. Most existing approaches are either energy inefficient or lack of fault tolerance in the environment of mobile targets and mobile sinks. Motivated by these, we propose an energy-efficient line proxy target detection (LPTD) approach in this paper. The basic idea of LPTD is to use designated line proxies as rendezvous points (or agents) to coordinate mobile sinks and mobile targets. Instead of having rendezvous nodes for each target type as used by most existing approaches, we adopt the temporal-based hash function to determine the line in the given time. Then the lines are alternated over time in the entire sensor network. This simple temporal-based line rotation idea allows all sensor nodes in the network to serve as rendezvous points and achieves overall load balancing. Furthermore, instead of network-wide flooding, interests from sinks will be flooded only to designated line proxies within limited area. The interest flooding can further decrease if the interest has geographical constraints. We have conducted extensive analysis and simulations to evaluate the performance of our proposed approach. Our results show that the proposed approach can significantly reduce overall energy consumption and target detection delay. Copyright © 2007 John Wiley & Sons, Ltd. [source] Impact of Redhat IPv6 router on heterogeneous host connectionsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2007Sulaiman Syed Mohamed Abstract Internet's popularity has been expanding on dramatic pace and the number of people getting connected to it multiplies regularly. With this high demand, the current Internet Protocol (IPv4) has reached its limits. The next generation Internet Protocol version6 (IPv6) has been incorporated into various operating systems. The motivation behind this work is how well IPv6 co-operates with various operating systems. The performance of the IP stack, together with the behaviour of the OS greatly affects the efficiency of network applications built on top of it. The acceptance of IPv6 implementations on various operating systems heavily relies on the end-user performance. In this paper, we propose to analyse these various IPv6 implementations for its host and router-level supports. In this paper, we investigate the impact of Redhat-based IPv6 router on IPv6 stacks of three different operating systems namely, Windows2003, Redhat Linux 9.0 (Redhat9.0) and FreeBSD4.9. Copyright © 2006 John Wiley & Sons, Ltd. [source] A study on a receiver-based management scheme of access link resources for QoS-controllable TCP connectionsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2006Kazuhiro Azuma Abstract Although the bandwidth of access networks is rapidly increasing with the latest techniques such as DSL and FTTH, the access link bandwidth remains a bottleneck, especially when users activate multiple network applications simultaneously. Furthermore, since the throughput of a standard TCP connection is dependent on various network parameters, including round-trip time and packet loss ratio, the access link bandwidth is not shared among the network applications according to the user's demands. In this thesis, we present a new management scheme of access link resources for effective utilization of the access link bandwidth and control of the TCP connection's throughput. Our proposed scheme adjusts the total amount of the receive socket buffer assigned to TCP connections to avoid congestion at the access network, and assigns it to each TCP connection according to characteristics in consideration of QoS. The control objectives of our scheme are (1) to protect short-lived TCP connections from the bandwidth occupation by long-lived TCP connections, and (2) to differentiate the throughput of the long-lived TCP connections according to the upper-layer application's demands. One of the results obtained from the simulation experiments is that our proposed scheme can reduce the delay of short-lived document transfer perceived by the receiver host by up to about 90%, while a high utilization of access link bandwidth is maintained. Copyright © 2006 John Wiley & Sons, Ltd. [source] Reliable ALE middleware for RFID network applicationsINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 3 2009Nong-Kun Chen Radio frequency identification (RFID) technology adopts the air interface to deliver the information required for object identification. The RFID system is convenient to manage and operate, and is widely encouraged by the large-scale chain industry. Additionally, electronic product code (EPC) network technology allows immediate, automatic identification and sharing of information on items in the supply chain. This work proposes an RFID service middleware with a highly reliable and efficient application-level event (ALE)-based prototype mechanism according to EPCglobal. A Student Muster Roll (SMR) application test bed is implemented in the proposed ALE-based scheme. The SMR system can be employed to manage the absentee records of students in a class, and can manage and control several operation multi-reader devices simultaneously. The proposed scheme can filter attendance accurately, eliminating the possibility of reduplication in student records. Performance evaluation results indicate that the proposed novel scheme is much more efficient and reliable than a naive ALE scheme. Copyright © 2008 John Wiley & Sons, Ltd. [source] A new video compression algorithm for different videoconferencing standardsINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2003Dr Awad Kh. In this paper, a new and simple predictive coding algorithm for video compression and multimedia communication for different network applications is investigated. This algorithm is called semi-hexagonal absolute moment block truncation coding (SH-AMBTC). It enjoys better objective and subjective qualities over the standard square shaped AMBTC. This technique based on the prediction of the bit-map of the middle frames in a sequence from the bit-map of the end frames (the first and the last frames in the group). It is of very low complexity comparing to the standard algorithm MPEG. The new algorithm adds no complexity to the existing AMBTC algorithm. Copyright © 2002 John Wiley & Sons, Ltd. [source] Cross-validation of neural network applications for automatic new topic identificationJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 3 2008H. Cenk Ozmutlu The purpose of this study is to provide results from experiments designed to investigate the cross-validation of an artificial neural network application to automatically identify topic changes in Web search engine user sessions by using data logs of different Web search engines for training and testing the neural network. Sample data logs from the FAST and Excite search engines are used in this study. The results of the study show that identification of topic shifts and continuations on a particular Web search engine user session can be achieved with neural networks that are trained on a different Web search engine data log. Although FAST and Excite search engine users differ with respect to some user characteristics (e.g., number of queries per session, number of topics per session), the results of this study demonstrate that both search engine users display similar characteristics as they shift from one topic to another during a single search session. The key finding of this study is that a neural network that is trained on a selected data log could be universal; that is, it can be applicable on all Web search engine transaction logs regardless of the source of the training data log. [source] Dual-band filter design of combined half and quarter wavelength SIRs for WLAN applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2008Pow-Wen Chen Abstract This article presents a dual-band bandpass filter composed of ,/2 and ,/4 stepped impedance resonators for the wireless local area network applications. The filter covers both the operating frequencies of 2.45 GHz and 5.2-5.8 GHz. The doubly parallel-coupling mechanism is used in the filter design to reduce the insertion losses and to gain a wider bandwidth. The cross coupling configuration and the tapped-line I/O feed are adopted in this filter design to provide the attenuation poles for improving the signal selectivity and stopband rejection levels. Experiments were conducted to verify the circuit performance. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 13,15, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22979 [source] Miniaturized microstrip meander-line antenna with very high-permittivity substrate for sensor applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2007Haiwen Liu Abstract This article presents a compact microstrip meander-line antenna for sensor network applications in the 290 MHz band. The antenna is fed by coplanar waveguide and its dimension is 15 mm × 15 mm × 2 mm. Because of the use of a very high relative permittivity substrate (,r = 90) and meander-line structure simultaneously, the side length of the designed antenna is about ,g/12 (,g is the guided wavelength) so that the circuit size is reduced greatly. Measurements verify that the proposed antenna has bandwidth of 12% at the resonant frequency of 293 MHz. Also, the radiation patterns measured at resonance frequencies are very close to omnidirectional in the E-plane. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2438,2440, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22798 [source] Microstrip dual-band bandpass filter using slow-wave resonators for WLAN applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2007Xuehui Guan Abstract A dual-band bandpass filter using microstrip slow-wave resonators is developed for wireless local area network applications. The fundamental and higher order resonant harmonics of a microstrip open-loop resonator are analyzed against the length of the loading open stub. Then a dual-band bandpass filters is designed in the form of slow-wave open-loop resonators. A zero-degree feed structure is employed to produce transmission zeros near the passband to increase the rate of attenuations, and a quarter-wavelength feed line for impedance matching is added to get desired external quality factor at the input and output. The theoretical analysis and design procedures are successfully verified by experimental results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 14,16, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22055 [source] Maximum likelihood estimators of clock offset and skew under exponential delaysAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 4 2009Jun Li Abstract Accurate clock synchronization is essential for many data network applications. Various algorithms for synchronizing clocks rely on estimators of the offset and skew parameters that describe the relation between times measured by two different clocks. Maximum likelihood estimation (MLE) of these parameters has previously been considered under the assumption of exponentially distributed network delays with known means. We derive the MLEs under the more common case of exponentially distributed network delays with unknown means and compare their mean-squared error properties to a recently proposed alternative estimator. We investigate the robustness of the derived MLE to the assumption of non-exponential network delays, and demonstrate the effectiveness of a bootstrap bias-correction technique. Copyright © 2009 John Wiley & Sons, Ltd. [source] Multiple neural networks modeling techniques in process control: a reviewASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009Zainal Ahmad Abstract This paper reviews new techniques to improve neural network model robustness for nonlinear process modeling and control. The focus is on multiple neural networks. Single neural networks have been dominating the neural network ,world'. Despite many advantages that have been mentioned in the literature, some problems that can deteriorate neural network performance such as lack of generalization have been bothering researchers. Driven by this, neural network ,world' evolves and converges toward better representations of the modeled functions that can lead to better generalization and manages to sweep away all the glitches that have shadowed neural network applications. This evolution has lead to a new approach in applying neural networks that is called as multiple neural networks. Just recently, multiple neural networks have been broadly used in numerous applications since their performance is literally better than that of those using single neural networks in representing nonlinear systems. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Generalized MPLS-based distributed control architecture for automatically switched transport networksBELL LABS TECHNICAL JOURNAL, Issue 1 2001Yangguang Xu Current circuit-switched transport networks, such as plesiochronous digital hierarchy (PDH) and synchronous optical network/synchronous digital hierarchy (SONET/SDH), have traditionally used centralized network management for connection control. To facilitate the value-added capabilities of today's networks,such as the rapid provisioning of services, dynamic setup of bandwidth requests, and fast mesh-based restoration,distributed connection control using signaling protocols has quickly gained industry momentum. Efforts have been initiated in various standards bodies to define the automatically switched transport network (ASTN). Although many architectural choices are now available, this paper describes a distributed control plane architecture that can be applied to various circuit-switching technologies and different network applications. This architecture adopts the concept of a generalized version of multiprotocol label switching (MPLS), which extends and modifies MPLS and other protocols on the Internet to make them applicable to various transport networks and also facilitates optical data networking. Four major functional components are incorporated in this architecture: element-level resource discovery, state information dissemination, path selection, and path control modules. Using these concepts, the transport network can be viewed as a virtual nonblocking, reconfigurable backplane of different network clients. This view represents a radical departure from the traditional data networking view of transport networks as providing fixed pipes and will have a dramatic impact on future network interworking and end-to-end traffic engineering (TE). [source] Artificial neural networks applications in building energy predictions and a case study for tropical climatesINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2005Melek Yalcintas Abstract This study presents artificial neural network (ANN) methods in building energy use predictions. Applications of the ANN methods in energy audits and energy savings predictions due to building retrofits are emphasized. A generalized ANN model that can be applied to any building type with minor modifications would be a very useful tool for building engineers. ANN methods offer faster learning time, simplicity in analysis and adaptability to seasonal climate variations and changes in the building's energy use when compared to other statistical and simulation models. The model herein is presented for predicting chiller plant energy use in tropical climates with small seasonal and daily variations. It was successfully created based on both climatic and chiller data. The average absolute training error for the model was 9.7% while the testing error was 10.0%. This indicates that the model can successfully predict the particular chiller energy consumption in a tropical climate. Copyright © 2005 John Wiley & Sons, Ltd. [source] Design of triangular slot antenna for triple-band (2.4/5.2/5.8 GHz) antenna with fork-like tuning stubMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2007J. H. Yoon Abstract A novel design for a triangular slot antenna with fork-like tuning stub for 2.4/5.2/5.8 GHz triple-band applications is presented in this article. The prototype consists of a triangular slot and a fork-like tuning stub. The triangular slot is fed by a 50-, microstrip line with a fork-like tuning stub, which is printed on the opposite side of the microwave substrate. As seen in the experimental results, the impedance bandwidth (VSWR 1:2) of the proposed bandwidth is about 550 MHz for the 2.4-GHz band and 1.736 GHz for the 5-GHz band. This is a microstrip antenna for IEEE 802.11a/b wireless local area networks applications. Simulated and experimental results for the return loss, radiation patterns, and gains are presented and discussed.© 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1561,1565, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22499 [source] | ||||||||||||||||