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• The proposed approach is mainly based on the magnetic behavior of the power system before and during faulty conditions. • The strategy of the approach is much simpler, and imposes less computational burden. However, it is applicable only for unsymmetrical faults with lower resistances. • The efficiency of the new method depends on the reliable determination of the current's and voltage's phasors, and the accuracy of instruments measurements. A power distribution system (PDS) is a crucial component of the electrical power system. Faults frequently occur over the PDS; which can usually cause damage to the entire power system and need time and effort to detect, locate and eliminate them. The proposed parameter-free fault location algorithms used measurements from two or multi-terminals of the power system, which are not always available, especially in power distribution systems, where measurements are usually available only from a single-end. This paper proposes a new parameter-free fault location approach in a PDS. The approach is mainly based on the magnetic behavior of the power distribution system before and during faulty conditions. The suggested approach only takes advantage of post-fault voltage and current measurement from one-terminal disregarding line parameters. Computer simulations using standard and real field power distribution systems are reported and have shown quite encouraging results. The strategy of the approach is much simpler, and imposes less computational burden. However, it is applicable only for unsymmetrical faults with lower resistances. Evaluation studies on two different PDS have demonstrated quite promising results. However, the present work does not consider the sensitivity of the new approach to the quality of phasors' extraction and the impact of CTs and VTs [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract The design, modeling, optimization, and development of the entire ultrasonic imaging system is a complex task which involves an understanding of acoustic physics of transducer, acoustic properties of propagating medium, transmission cables and analog front-end electronics for generating and receiving of ultrasonic signals. Such immersion systems are extensively utilized in non-destructive testing (NDT) application for flaw detection, dimensional measurements, material characterization and many more. This paper presents the one-dimensional simulation modeling of the entire ultrasonic imaging system. For validation purpose, a single channel real-time ultrasonic imaging system has been designed and developed for laboratory application which contains high voltage ultrasonic spike pulser, high voltage protection circuits, ultrasonic receiver amplifiers, co-axial cables and an ultrasonic transducer. Lossless and lossy (low-loss) simulations have been performed for ultrasonic transducer and propagation medium using the transmission line model. Effects of non-ideal, frequency-dependent and non-linear components in high voltage excitation circuit (pulser), the receiver circuit and the effects of cables are also considered for modeling and simulation. Validation results of the entire ultrasonic imaging system provide very close agreement with lossy simulated results. [ABSTRACT FROM AUTHOR]

The paper proposes a novel adaptive control of the human musculoskeletal arm model in order to simulate reaching movements of the human upper extremity. The controller is based on a normalized radial basis function neural network, which takes the Actor-Critic structure. The normalized radial basis function neural network simultaneously approximates the policy function of the actor network and the value function of the critic network. An adaptive adjustment mechanism is dynamically established to realize the state space constructions. The approach could effectively overcome the curse of dimensionality caused by state space division and always keep the structure in an optimal state. The human arm model adopts a Hill-type model with two joints, six muscles. As a validation, numerical simulations are performed to achieve the reaching movements of the human upper extremity. The results show that the adaptive control can well instruct the human arm model to mimic the reaching movements. [ABSTRACT FROM AUTHOR]

With the increasing consumption of energy in data centers, the demand for energy efficient multiprocessor job scheduling is growing dramatically. Besides flow time, energy conservation has become a significant issue and drawn enormous interest. In this paper, an online non-clairvoyant scheduling algorithm Significance-based Multiprocessor Round Robin (SbMRR) is proposed. SbMRR utilizes the unbounded speed model, where the range of the speed of any processor is from zero to infinity. To validate the effectiveness of the algorithm, mathematical and simulation-based analysis are conducted which demonstrates that SbMRR provides the minimum sum of significance-based flow time and energy consumed. SbMRR is O(α)-competitive, more precisely ((α + 1)⁄((1–1⁄αβ)))-competitive, where β ≥ 4 a constant. The competitive ratio of SbMRR is least to date. SbMRR provides the minimum sum of energy consumed and significance-based flow-time. [ABSTRACT FROM AUTHOR]

The paradigm of the Social Internet of Things (SIoT) boosts a new trend wherein the connectivity and user friendliness benefits of Social Network Services (SNS) are exhibited within the network of connected objects, i.e. the Internet of Things (IoT). The SIoT exceeds the more traditional paradigm of IoT with an enhanced intelligence and context-awareness. In this paper, a novel service framework based on a cognitive reasoning approach for dynamic SIoT services discovery in smart spaces is proposed. That is, reasoning about users’ situational needs, preferences, and other social aspects along with users’ surrounding environment is proposed for generating a list of situation-aware services which matches users’ needs. This reasoning approach is then implemented as a proof-of-concept prototype, namely Airport Dynamic Social, within a smart airport. Finally, an empirical study to evaluate the reasoning approach's efficiency shows improved services adaptability to situational needs compared to common approaches proposed in literature. [ABSTRACT FROM AUTHOR]

Although the IEEE 802.11 wireless local area network (WLAN) provides users of mobile device a convenient method to connect to the Internet, the load of access points (APs) may have a strong impact on the performance of a WLAN, such as the congestion problem. To avoid this issue and to maximize the performance and scalability of a WLAN, an effective method for balancing the load of APs, called a modified multiple-search multi-start framework based micro-genetic algorithm, is presented in this paper. Simulation results show that the proposed algorithm gives a much better solution than the original genetic algorithm does in terms of both the quality and the computation time. [ABSTRACT FROM AUTHOR]

Mission-critical military operations with dismounted soldiers are frequently characterized by high battlefield dynamics. In such scenarios a mobility model can manage soldiers’ movements dynamically especially under enemy attacks. This paper presents a group mobility model simulating realistic soldier and leader battlefield behaviors. Our model analyzes communication between a group of dismounted soldiers deployed in a mobile ad hoc network (MANET) and their leader under several perturbation factors (e.g., noise and enemies attacks) which affect movements and topology connectivity. Results show that the dismounted soldiers’ collective movement improves the capacity of communication channels, whereas noise uncertainty may dramatically destroy the network. Moreover, the enemy’s presence, another disorder parameter, changes qualitatively and quantitatively the army’s wireless communication topology. Enemy numbers decrease almost linearly the throughput at the sink node (commander). A discussion of results follows, using distributions of path lifetimes, path lengths, packet delivery and group sizes in the communication soldiers’ network. [ABSTRACT FROM AUTHOR]

In wireless sensor networks, hostile deployment terrains make resource constrained sensor nodes vulnerable to failures. Sometimes, even a single node failure can partition a network into many disjoint segments and can fail the application mission completely. Since, in most scenarios manual intervention is not possible and hence network must have self-healing capability by detecting and recovering faults at its own. In this paper, a distributed connectivity restoration (DCR) scheme is proposed which on node failure(s) reconstructs the network topology by using cascaded node movements enabling self-healing capability in the network. The DCR is based on partial network information including topological overhead associated with each node. The selection of befitting nodes to be relocated during cascaded movement is done strategically by using partial network information such that the relocation and message overheads are reduced. Ns-2 based simulation experiments are performed to evaluate the performance of the proposed scheme and is compared with other baseline approaches. [ABSTRACT FROM AUTHOR]

This paper presents a new particle swarm optimization (PSO) algorithm, called the PSO-IAC algorithm, to resolve the goal of reaching with the obstacle avoidance problem for a 6-DOF manipulator of the home service robot. The proposed PSO-IAC algorithm integrates the improved adaptive inertia weight and the constriction factor with the standard PSO. Both the free-space and obstacle avoidance states are established for evaluations in computer simulations and real-time experiments. The performance comparisons of the PSO-IAC algorithm with respect to the existing inertia weighted PSO (PSO-W), constriction factor based PSO (PSO-C), constriction factor and inertia weighted PSO (PSO-CW), and adaptive inertia weighted PSO (PSO-A) algorithms are examined. Simulation results indicate that the PSO-IAC algorithm provides the fastest convergence capability. Finally, the proposed control scheme can make the manipulator of the home service robot arrive at the goal position with and without obstacles in all real-time experiments. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with robust blind linear minimum mean square error (LMMSE) detection using the particle swarm optimization (PSO) algorithm in the presence of code mismatch. The paper shows that the PSO algorithm incorporating the linear system of the LMMSE detector, which is termed as LPSO, can significantly improve the bit error rate (BER) and the system capacity. As the code mismatch occurs, the output BER performance is vulnerable to degradation for LPSO. To remedy this problem, a blind LMMSE scheme is proposed and combined with PSO to form a robust blind LPSO (BLPSO) detector under code mismatch scenarios. Several computer simulations are provided to demonstrate the effectiveness of the proposed scheme. [Copyright &y& Elsevier]

Abstract: This paper introduces a nonlinear function into the frequency spectrum that improves the detection of vowels, diphthongs, and semivowels within the speech signal. The lower efficiency of consonant detection was solved by implementing the hangover and hangbefore criteria. This paper presents a procedure for faster definition of those optimal constants used by hangover and hangbefore criteria. A nonlinearly changed frequency spectrum is used in the proposed GMM (Gaussian Mixture Model) based VAD (Voice Activity Detection) algorithm. Comparative tests between the proposed VAD algorithm and seven other VAD algorithms were made on the Aurora 2 database. The experiments were based on frame error detection and on speech recognition performance for two types of acoustic training modes (multi-condition and clean only). The lowest average percentage of frame errors was obtained by the proposed VAD algorithm, which also achieved positive improvement in the speech recognition performance for both types of acoustic training modes. [Copyright &y& Elsevier]

Abstract: This paper addresses the field of stereophonic acoustic echo cancellation (SAEC) with adaptive filtering algorithms. In SAEC applications, using the least mean square (LMS) algorithm, it is usually assumed that the lengths of the adaptive filters are equal to that of the unidentified system responses. Although, in many realistic situations, under-modelled lengths adaptive filters, whose lengths are less than that of the unidentified systems (under-modelled systems), are employed, and analysis results for the exact modelled stereophonic LMS algorithm are not automatically appropriate to the under-modeled lengths. In this paper, we present a statistical analysis of the under-modeled stereophonic LMS algorithm. Exact expressions and deterministic recursive equations to the mean coefficients behavior of the adaptive LMS filters are derived to completely characterize and assess the performances (transient and steady-state) of the under-modeling stereophonic LMS algorithm. The expected theoretical behaviour is compared with Monte Carlo simulations and practical experimental results, showing a very good agreement. [Copyright &y& Elsevier]

Abstract: This paper addresses the field of stereophonic acoustic echo cancellation (SAEC) by adaptive filtering algorithms. Recently, we have proposed a new version of the fast Newton transversal FNTF algorithm for SAEC applications. In this paper, we propose an efficient modification of this algorithm for the same applications. This new algorithm uses a new proposed and simplified numerical stabilization technique and takes into account the cross-correlation between the inputs of the channels. The basic idea is to introduce a small nonlinearity into each channel that has the effect of reducing the inter-channel coherence while not being noticeable for speech due to self masking. The complexity of the proposed algorithm does not alter the complexity of the original version and is kept less than half the complexity of the fastest two-channel FTF filter version. Simulation results and comparisons with the extended two-channel normalized least mean square NLMS and FTF algorithms are presented. [Copyright &y& Elsevier]

Abstract: Compressed sensing (CS) is considered as a promising signal processing technique, and successful applications of the CS theory depend mainly on the accuracy and speed of the reconstruction algorithms. In this paper, a generalized objective functional, which has been developed using the combinational estimation and an extended stabilizing functional, is proposed. An efficient iterative scheme, which integrates the beneficial advantages of the homotopy method, the shuffled frog-leaping (SFL) algorithm and the harmony search (HS) algorithm, is designed for searching a possible global optimal solution. Numerical simulations are implemented to evaluate the numerical performances and effectiveness of the proposed algorithm. Excellent numerical performances and encouraging results are observed. For the cases considered in this paper, a dramatic improvement in the reconstruction accuracy is achieved, which indicates that the proposed algorithm is a promising candidate for solving CS inverse problem. [Copyright &y& Elsevier]

Abstract: In this paper, we will investigate the implementation of the parallelization approaches used in the program of discharge simulation along resin insulator surfaces in SF6/N2 gas mixture which initially consumes a great deal of computational time. In a general way, this simulation program spent 10 days of execution to achieve satisfactory research results. For this reason, the goal of our paper is to reduce the execution time by parallelizing this program. Three parallelization approaches were used in our simulation: (i) splitting by different types of the charged particles using a distributed-memory approach, (ii) splitting by physical domain using a distributed-memory approach, and (iii) splitting by both domain and charged particles using multi-level distributed and shared memory approach. At last, the three approaches are tested on a Linux cluster composed of six dual-core PCs, and the experimental results show that all the parallelization approaches achieve the goal of reducing the execution time to a certain extent. In addition, among these approaches, the multi-level approach offers the most effective parallelization method for implementing this simulation on symmetrical multi-processing (SMP) clusters. [ABSTRACT FROM AUTHOR]

Abstract: non-preemptive priority queue with bulk arrivals has already been analysed in many papers. Two problems are known in this area: first, when the number of priorities is greater than 2, the analysis for priority processes is obviously very difficult to handle. Therefore, the earlier work on the subject was restricted mostly to two priority classes; and second, although analytically explicit results are available, they require sophisticated closed-form expressions of the mean queue length. One particular bulk size distribution – the GE distribution – is motivated by an ME (Maximum Entropy) formulation for the behavior of a G/G/1 queue. The choice of a GE distribution is motivated by the fact that measurements of actual inter-arrival traffic or service times may be generally limited and so only few parameters, such as mean and variance, can be computed reliably. Thus this paper we can obtain very simple and analytic closed-form expression for the mean queue length of a GE/G/1 priority queue and a significant increase in performance evaluation has been achieved. We present the four-class priority queues, performance analysis and simulation of the LER (Label Edge Router) system in the ATM-based MPLS (Multiprotocol Label Switching) network. We wish to obtain the boundary conditions of the mean queue lengths and the mean queueing delays for each priority class, since this metric is one of the most important in performance evaluation parameters for improving QoS and system performance of the LER system in ATM-based MPLS network. A significant numerical example is presented and discussed as well. In order to obtain optimizing the performance analysis for EF flow, AF 1 flow, AF 2 flow and BE flow, the optimum ratios of COV (Coefficient of Variation) can be found via many numerical experiments carried out by the authors for queueing network model with HOL (Head of Line) priority rules. However, the ratios of COV value constraints exist. Furthermore, we find that each service class gradually begins to deteriorate when SQVs (Squared Coefficient of Variations), , and traffic intensity is greater than 0.95. We also find the values of maximum allowed burst size for EF flow and AF 1 flow and perform necessary policing actions on EF flow and AF 1 flow at the boundary node of the network. Finally, the four-class GE/G/1 priority queues and performance analysis of the LER system are shown accurate and robust after the comparison between theoretical evaluates and computer simulation results. [Copyright &y& Elsevier]

Abstract: This paper presents a transaction level SystemC model of an avionics mission system data bus that provides cycle-accurate simulation of the bus. The mission system is a complex distributed computer network consisting of a mission control computer, radars, an array of subsystems and sensors. The data bus plays a critical role in the system as it carries all the information between the system components. Therefore modelling the bus at an appropriate level of abstraction using appropriate technology is important for evaluation of the performance of both the bus and the entire system. While models based on traditional hardware description languages (HDL) provide cycle-accurate performance estimates they are very slow and have high code complexity. In order to enhance model performance this paper presents a transaction level model (TLM) utilizing the enhanced SystemC features and levels of abstraction. The TLM model incorporates a clock-based synchronisation strategy thereby providing cycle-accurate performance estimates like the HDL models. The developed model has been validated for various payloads and system sizes. Simulation results show that the proposed SystemC transaction level model is much more efficient than models developed using conventional hardware description languages. [Copyright &y& Elsevier]

This paper describes a novel method of chaotic time series prediction, which is based on the fundamental characteristic of chaotic behavior that sensitive dependence upon initial conditions (SDUIC), and Lyapunov exponents (LEs) is a measure of the SDUIC in chaotic systems. Because LEs of chaotic time series data provide a quantitative analysis of system dynamics in different embedding dimension after embedding a chaotic time series in different embedding dimension phase spaces, a novel multi-dimension chaotic time series prediction method using LEs is proposed in this paper. This is done by first reconstructing a phase space using chaotic time series, then using LEs as a quantitative parameter to predict an unknown phase space point, after transferring the phase space point to time domain, the predicted chaotic time series data can be obtained. The computer simulation result of simulation showed that the proposed method is simple, practical and effective. [Copyright &y& Elsevier]

The Multi-Carrier Interleave Division Multiple Access (MC-IDMA) scheme combines Orthogonal Frequency Division Multiplexing and IDMA. The scheme combats both Inter-Symbol Interference (ISI) and Multiple Access Interference (MAI). For coherent detection of the transmitted signals at the receiver, Channel State Information (CSI) is crucial. There are several schemes that can be used to obtain CSI at the receiver, such as pilot-based schemes and decision directed scheme, semi-blind and as blind channel estimation schemes. This paper focuses on developing semi-blind channel estimation scheme for the MC-IDMA systems. The developed scheme is based on Minimum Mean Square Error (MMSE) algorithm. The estimator employs applications of the eigenvalue and eigenvector decomposition (EVD) techniques to simplify the MMSE algorithm, and is named Simplified Mean Value Estimator (SMVE). Simulation results show that the proposed SMVE-based estimator outperforms Least Mean Square (LMS) algorithm-based estimator, Modified Minimized Mean Value Estimator (MMMVE), and the Minimized Mean Value-MMSE Estimator (MMVE). [ABSTRACT FROM AUTHOR]

In this paper, an improved particle swarm optimization guidance (IPSOG) is proposed. The particle swarm optimization guidance (PSOG) is presented to solve nonlinear and dynamic missile guidance problems. However, the miss distance (MD) tends to be large. The objective function of the relative distance in the PSOG leads the missile to the current position of a target. Therefore, the PSOG is similar to pursuit guidance. In the IPSOG, a new objective function for the PSOG is introduced to improve the guidance performance. The line-of-sight (LOS) rate is taken as the objective function. The fitness function is then evaluated according to the defined objective function. Numerical simulation results show that the guidance performance of the IPSOG is better than the PSOG. [ABSTRACT FROM AUTHOR]

This paper proposes a dual mode guidance, which is called the proportional navigation-improved particle swarm optimization guidance (PN-IPSOG), in order to optimize the guidance performance of a missile. The improved particle swarm optimization guidance (IPSOG) has the advantages of a robustness and fast reaction, but the attitude of the missile is unstable in the initial phase. Therefore, proportional navigation (PN) guidance is used to adjust the attitude of the missile in the initial phase. Meanwhile, the angle μ that is between the tangent of the current line-of-sight (LOS) rate and the horizontal reference line is calculated. When a set of μ is close to zero, the PN-IPSOG switches from the PN guidance to the IPSOG. Numerical simulation results show that the performance of the PN-IPSOG is better than the PN guidance at miss distance and lateral accelerations. [ABSTRACT FROM AUTHOR]

Embedding secret information into a cover media and extracting the information and the image without any distortion is known as reversible watermarking (RW). This paper analyzes the performance of hybrid local prediction error-based RW using difference expansion (DE). The cover medical image is split into non-overlapping blocks. The border pixels in each block are predicted using median edge detection (MED) prediction. The other pixels in the block are predicted using least square prediction, and the prediction error is expanded. The secret data are embedded into the cover medical image corresponding to the prediction error using the DE method. The predictor is also embedded into the cover medical image to recover the data at detection without any additional information. The simulation results show that, this method achieves better watermarked image quality and high embedding capacity when compared to other classical prediction methods: Median, MED, Rhombus and Gradient Adjusted Prediction. [ABSTRACT FROM AUTHOR]

The traditional approach for energy detection (ED) consists in the comparison of the energy received against a fixed detection threshold, estimated according to an expected noise level. However, the noise power is not a static parameter since it varies as a function of the random sources of noise and interference present in the network. This random nature of the noise power originates the so-called noise uncertainty problem which adversely affects the performance of the ED. In this paper, we propose and evaluate by means of computer simulation an adaptive energy detector that incorporates a noise power estimation strategy for adjusting the detection threshold according to the noise power present at each sensing epoch. As it can be proved by simulation results, our strategy helps in reducing the sensing errors and to improve the ED's sensitivity by alleviating the negative effects of the noise uncertainty. [ABSTRACT FROM AUTHOR]

The objective of this work is to analyse performance of unstable mobile nodes with self-organization structures in Delay Tolerant Networks (DTN). This process enables the nodes to utilize their power fairly, and ensures that the links are established between nodes and used to improve the connectivity. In this paper two approaches are proposed: 1. Self-Healing (SH) and 2. Unstable Topology Structure (UTS) approaches based on localized computations. The proposed work is proven with simulations by analysing node degree, coverage area and Quality of Service (QoS) parameters. The performance of the work is analysed in a network simulator with mathematical models. [ABSTRACT FROM AUTHOR]

The risk of reinsurance portfolios covering globally occurring natural catastrophes, such as earthquakes and hurricanes, is quantified by employing simulations. These simulations are computationally intensive and require large amounts of data to be processed. The use of many-core hardware accelerators, such as the Intel Xeon Phi and the NVIDIA Graphics Processing Unit (GPU), are desirable for achieving high-performance risk analytics. In this paper, we set out to investigate how accelerators can be employed in risk analytics, focusing on developing parallel algorithms for Aggregate Risk Analysis, a simulation which computes the Probable Maximum Loss of a portfolio taking both primary and secondary uncertainties into account. The key result is that both hardware accelerators are useful in different contexts; without taking data transfer times into account the Phi had lowest execution times when used independently and the GPU along with a host in a hybrid platform yielded best performance. [ABSTRACT FROM AUTHOR]

Aerial image simulation is a fundamental problem in advanced lithography for chip fabrication. Since it requires a huge number of mathematical computations, an efficient yet accurate implementation becomes a necessity. In the literature, graphic processing unit (GPU) or multi-core single instruction multiple data (SIMD) CPU has demonstrated its potential for accelerating simulation. However, the combination of GPU and multi-core SIMD CPU was not exploited thoroughly. In this paper, we present and discuss collaborative computing algorithms for the aerial image simulation on multi-core SIMD CPU and GPU. Our improved method achieves up to 160× speedup over the baseline serial approach and outperforms the state-of-the-art GPU-based approach by up to 4× speedup with a hex-core SIMD CPU and Tesla K10 GPU. We show that the performance on the collaborative computing is promising, and the medium-grained task scheduling is suitable for improving the collaborative efficiency. [ABSTRACT FROM AUTHOR]

The diffusion equation model is a popular tool in room acoustics modeling. The 3-D Finite Difference (3D-FD) implementation predicts the energy decay function and the sound pressure level in closed environments. This simulation is computationally expensive, as it depends on the resolution used to model the room. With such high computational requirements, a high-level programming language (e.g., Matlab) cannot deal with real life scenario simulations. Thus, it becomes mandatory to use our computational resources more efficiently. Manycore architectures, such as NVIDIA GPUs or Intel Xeon Phi offer new opportunities to enhance scientific computations, increasing the performance per watt, but shifting to a different programming model. This paper shows the roadmap to use massively parallel architectures in a 3D-FD simulation. We evaluate the latest generation of NVIDIA and Intel architectures. Our experimental results reveal that NVIDIA architectures outperform by a wide margin the Intel Xeon Phi co-processor while dissipating approximately 50 W less (25%) for large-scale input problems. [ABSTRACT FROM AUTHOR]

This paper discusses the challenge in post-Peta and Exascale era especially that brought by manycore processors of ordinary (i.e., non-GPU type) CPU cores. Though such a processor like Intel Xeon Phi gives us TFlops-class computational power and may lead us to Exascale computing, full exploitation of its potential is far from an easy job due to its source of high performance, namely a large scale multithreading and a wide SIMD mechanism. In fact, in the three-tier parallelism namely inter-node, intra-node and intra-core ones, we found their order does not represent the toughness in HPC programming but the order should be reversed to do that. Our case study with a particle-in-cell plasma simulation code supports our observation revealing that a simple porting of an existing code to Xeon Phi is infeasible from the viewpoint of performance and we have to make a significant change of the code structure so that it conforms with the features of the processor. However the study also confirms that the recoding effort is well rewarded achieving a good single-node performance higher than that obtained from an execution on four dual-socket nodes of Cray XE6. [ABSTRACT FROM AUTHOR]

In this paper a dynamic modeling, simulation, control and energy management of photovoltaic water-pumping network system is presented. A fuzzy-logic controller has been proposed for a real-time control of the system. The controller generates the reference speeds needed for the pulse-width-modulation generator to control each DC/DC boost converter taking into account the water levels in three tanks and the instantaneous value of the solar radiation. The main objectives of the fuzzy-logic controller are the design of an adequate maximum power-point tracker to extract the maximum power, regulate the water in the three tanks and finally ensure the correct operation for all the conversion strings in order to optimize the quantity of pumped water. The system performance under different scenarios has been checked carrying out Matlab/Simulink simulations using a practical load-demand profile and real weather data and comparing them to another control algorithm. [ABSTRACT FROM AUTHOR]

An improved image magnification algorithm for gray and color images is presented in this paper to meet the challenge of preserving high-frequency components of an image, including both image edges and texture structures. In the proposed algorithm, a new edge detection method that uses the well-known Otsu automatic optimum thresholding is proposed to distinguish strong edge pixels. The parameters of the original directional cubic convolution interpolation algorithm, which were selected based on training, were eliminated. As a result, our algorithm achieves more accurate edge detection, better interpolation results, and less computational complexity. Simulation results demonstrate that the improved algorithm can reconstruct the magnified image, preserve edges and textures simultaneously, and reduce common interpolation artifacts. Furthermore, it generates higher visual quality of the magnified images and achieves higher peak signal-to-noise ratio, structural similarity, and feature similarity compared with other state-of-the-art methods. [ABSTRACT FROM AUTHOR]

This paper presents our ongoing efforts toward the development of a multi-agent distributed framework for autonomous control of mobile manipulators. The proposed scheme assigns a reactive agent to control each degree-of-freedom of the manipulator(s), a hybrid agent to control the mobile base, and a supervisory agent to coordinate and synchronize the work of the control agents. Each control agent implements a Simulation-Verification technique to optimize, locally and independently from the other agents, a predefined objective function. The final goal consists of bringing the end-effector as close as possible to imposed operational targets (reaching tasks). Different simulation scenarios are described and carried out for the case of RobuTER / ULM robot, with and without considering failures of some articulations of the manipulator or the mobile base. Results show that the main advantage of the proposed approach is that the system pledges a fault-tolerant response to some breakdowns without needing any specific additional treatment. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, optimal sets of filter coefficients are searched by a meta-heuristic optimization technique called Harmony Search (HS) algorithm for infinite impulse response (IIR) system identification problem. For different optimization problems, HS algorithm undergoes three basic rules; namely Random Selection (RS), Harmony Memory Consideration (HMC), and Pitch Adjustment (PA) rules, which are inspired from the process that the musicians use to improvise a perfect state of harmony with the consummate skill of blending notes in tune. With the help of the properly selected control parameters, a perfect balance is achieved in exploration and exploitation in searching phases. The detailed analysis of simulation results emphasizes the strength of HS algorithm to find the near-global optimal solution, quality of convergence profile and the speed of convergence while tested against standard benchmark examples for same and reduced order models. [Copyright &y& Elsevier]

Abstract: Here, the design and implementation of an on-chip clock generator which is needed for a switched capacitor based embedded DC–DC converter is described. The strategies that should be taken during making the design by predicting the occurrence of the parasitic issues at the time of implementation to keep the performance of the clock generator at per in silicon are also elaborated. The reported measurement results closely match with the simulation results in clock generation. It can be a helpful tutorial paper to design and implement an on-chip clock generator suitable for mid-frequency, real time applications. [Copyright &y& Elsevier]

Abstract: High density of coexisting networks in the Industrial, Scientific and Medical (ISM) band leads to static and self interferences among different communication entities. The inevitability of these interferences demands for interference avoidance schemes to ensure reliability of network operations. This paper proposes a novel Diversified Adaptive Frequency Rolling (DAFR) technique for frequency hopping in Bluetooth piconets. DAFR employs intelligent hopping procedures in order to mitigate self interferences, weeds out the static interferer efficiently and ensures sufficient frequency diversity. We compare the performance of our proposed technique with the widely used existing frequency hopping techniques, namely, Adaptive Frequency Hopping (AFH) and Adaptive Frequency Rolling (AFR). Simulation studies validate the significant improvement in goodput and hopping diversity of our scheme compared to other schemes and demonstrate its potential benefit in real world deployment. [Copyright &y& Elsevier]

Abstract: Opportunistic routing is an emerging research area in Wireless Mesh Networks (WMNs), that exploits the broadcast nature of wireless networks to find the optimal routing solution that maximizes throughput and minimizes packet loss. Opportunistic routing protocols mainly suffer from computational overheads, as most of the protocols try to find the best next forwarding node. In this paper we address the key issue of computational overhead by designing new routing technique without using pre-selected list of potential forwarders. We propose a novel opportunistic routing technique named, Coordinated Opportunistic Routing Protocol for WMNs (CORP-M). We compare CORP-M with well-known protocols, such as AODV, OLSR, and ROMER based on throughput, delivery ratio, and average end-to-end delay. Simulation results show that CORP-M, gives average throughput increase upto 32%, and increase in delivery ratio (from 10% to 20%). We also analyze the performance of CORP-M and ROMER based on various parameters, such as duplicate transmissions and network collisions, by analysis depicts that CORP-M reduces duplicate transmissions upto 70% and network collisions upto 30%. [Copyright &y& Elsevier]

Abstract: The use of WiMAX cellular networks has arisen as a promising solution in order to provide broadband access over large, often shadowed, areas. As in other cellular networks, localization of users is extremely useful for many services and even essential for some civilian and/or military logistic operations. In a cellular WiMAX network, a node can obtain its position from beacons received by several cell base stations. Therefore, securing the localization method against potential false or erroneous feedback is of paramount importance in order to allow the nodes to get reliable position estimations. This fact implies not only making the localization method robust against erroneous or forged measurements, but also identifying which WiMAX base stations are providing such measurements. In this paper, we propose a robust localization method that can identify up to k malicious or misbehaving base stations and provide with an accurate estimation of the node position even in their presence. Simulation results prove that this proposal outperforms other existing detection techniques. [Copyright &y& Elsevier]

Abstract: Robustness is an important issue in Wireless Sensor Networks (WSNs). In this paper, two topology evolution models based on complex network theory are proposed. A bayesian game clustering algorithm is used to achieve a uniform clustering, and topology evolution is executed among cluster heads according to random walk. Residual energy, node fitness, node saturation and communication radius are considered in the processes of topology evolution. Simulation results show that network topologies formed by the models are more in line with the practical application of WSNs and have a good robustness in harsh environment. [Copyright &y& Elsevier]

Abstract: Cooperative communication is a new physical technology, which has the potential to improve QoS support for multi-hop wireless network. Existing works did not consider the interference effect among links while designing cooperative QoS routing. To overcome this limitation, this paper targets at designing an interference-aware Cooperative QoS routing algorithm (CQ-routing) to satisfy users’ bandwidth requirement. We formulate the problem of finding cooperative routing path with maximum available bandwidth as an optimization problem, called Coop-routing problem. We prove that the Coop-routing problem is strong NP-hard. We propose both centralized and distributed algorithm to solve the Coop-routing problem. We prove that the centralized algorithm can achieve a constant approximation ratio. We evaluate the performance of these algorithms through simulations. The results show that CQ-routing algorithms can significantly improve the network performance in terms of available bandwidth and number of admitted flows. [Copyright &y& Elsevier]

Abstract: Control message delay is a major factor affecting distributed network utility maximization (NUM) in practical wireless mesh networks, and the inherent delay of the control response leads to severe oscillations and slow convergence. However, existing NUM techniques either fail to pay attention to the convergence rate or achieve suboptimal results. This paper proposes a novel technique to solve the reverse impact of inherent control delay in the distributed NUM of wireless mesh networks with noisy feedback by overcoming the slow convergence induced by control delay in conjunction with feedback noise. A self-tuning algorithm reduces the number of required iterations for convergence while also providing an optimum value in distributed networks, and substantive simulations prove this improved convergence performance within a distributed multi-hop wireless mesh network. A theoretical explanation built from the viewpoint of control theory is also put forward to describe the model. [Copyright &y& Elsevier]

Abstract: Rapid advances in sensor technology and wireless communications have led to the development of wireless sensor networks (WSNs). However, the sensor nodes in WSNs have a finite lifetime since it is often impractical, or even impossible, to recharge their batteries once they have been deployed. When the energy of a sensor node has been fully consumed, it can play no further role within the WSNs. In an attempt to prolong the lifetime of WSNs, various schemes have been proposed. This paper proposed a lifetime-extension under uniform distribution (LEUD) scheme which not only prolongs the lifetime of WSNs, but also optimizes its performance by maximizing the total number of active regions within the networks. To evaluate the effectiveness of our scheme, we chose three uniform distribution algorithms with LEUD to analyze and compared the performance of our scheme. Numerical simulations are performed which demonstrate that when the deployed sensor nodes have an equal initial energy and are distributed uniformly within the networks, LEUD provides an improved networks performance. [Copyright &y& Elsevier]

Abstract: In this paper we propose three packet switching optical network-on-chip architectures, i.e., TON-I, TON-II and TON-III. Micro-ring resonator (MRR)-based optical switches are adopted for wavelength-based routing in TONs. Direct optical channels (DOCs) are introduced as the direct optical paths between nodes. For each node in TON-I, II, and III, the number of DOCs is 4, 8, and 10 respectively. We present the implementations of a packet switching optical NoC with TONs with a limited number of wavelengths. The design of routers and schema for wavelength assignment are presented for each TON. The number of different wavelengths needed for in TON-I, II, and III is 2, 4, and 6. The proposed architectures yield highly scalabilities, high bandwidth, low latency and low power consumption. TON network performances are evaluated by simulation as presented. The transmission power loss analysis is provided as well. Simulation and analysis results show that the proposed architectures can be considered as a viable solution for future NoCs. [Copyright &y& Elsevier]

Abstract: Churn is a basic and inherent problem in P2P networks. A lot of relevant studies have been carried out, but all lack versatility. In this paper, a general solution is proposed which makes a peer-to-peer (P2P) network need not pay much attention to churn problem by introducing a logic layer named Dechurn, and most of churn could be eliminated in the Dechurn layer. For utilizing the complementary nature of node joining and leaving, a network scheme, named Constellation, for handling churn is designed on the Dechurn layer through which the resources cached in a node for its spouse node who has left network would be succeeded by a node in latent period. The simulation results indicate that the proposed solution is effective and efficient in handling churn and easy to put into practice. [Copyright &y& Elsevier]

Abstract: Active queue management has been proved to be an effective mechanism at the intermediate nodes to alleviate network congestion. A novel robust active queue management scheme based on H-infinity feedback control theory is proposed in this paper. A TCP model with link capacity disturbances, modeling uncertainties and time-varying delay is investigated, and the objective is to design a feedback controller which guarantee the queue length stability and robustness against the external disturbances and model perturbations. Meanwhile a simple on-line estimation of TCP window size is adopted instead of state observer which reduces computation burden significantly. The controller parameters are obtained through the standard linear matrix inequality techniques. Finally NS-2 simulation results demonstrate effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: The shrew DDoS attacks are stealth low-rate TCP-targeted DDoS attacks, which conceal their malicious activities into normal traffic. Although the good pretense eludes them from being detected in time domain, the existent energy exposes them in frequency domain. Online Power Spectral Density (PSD) analysis necessitates real-time PSD data conversion is a must. In this paper, an optimized FPGA based real-time PSD converter is proposed, which is based on our innovative component-reusable Auto-Correlation (AC) algorithm and the adapted 2N-point real-valued Discrete Fourier Transform (DFT) algorithm. Further optimization is achieved through the exploration of algorithm characters and hardware parallelism for this case. The evaluation results from both simulation and synthesis are provided. The conversion of a 512-point data sequence can be finished in the time interval of sampling one data point; and the overall design could be easily fitted in a Xilinx Virtex2 Pro FGPA. [Copyright &y& Elsevier]

Abstract: Multimedia services such as IPTV and video conferencing constitute a substantial portion of the traffic sources in new communication systems requiring high-speed IP switching. This paper presents a scalable architecture for a high-performance IP switch based on Priority Active Queue Management (PAQM), which provides multimedia services with improved quality of service (QoS) in the communication system. Better QoS, in terms of delay, throughput, and loss rate, can be provided by a packet scheduling technique and a buffer management architecture for packet switching networks. The proposed architecture consists of a PAQM with a dedicated memory management data structure based on circular linked lists. The linked lists include different priority levels in a pipelined organization for the management of active queues. The architecture also scales dynamically to support a large number of priority levels and a large queue size. A performance analysis of an optimized PAQM algorithm is presented using an NS-2 network simulator to evaluate the capacity of the IP switch to support QoS. The results show that this system can achieve the maximum throughput with low levels of delay. To achieve high performance, we have implemented the proposed algorithm using 0.35-μm CMOS technology, the performance of which is subsequently analyzed. [Copyright &y& Elsevier]

Abstract: This paper presents the effect of a single pulse dither signal injection in adaptive internal model controller for a doubly fed induction generator (DFIG)-based wind farm. Rotor current controller using adaptive internal model controller is designed with different Adjustment Mechanisms like Lyapunov theory, fuzzy and ANFIS to improve the voltage sag ride through. During voltage sag period the dither signal is injected in the controller to improve the performance of the controller. Simulation results are presented to demonstrate the proposed control strategy during variations in fixed and variable gain Adjustment Mechanism. [Copyright &y& Elsevier]

Abstract: Shared-memory multithreaded programs running on chip multiprocessors (CMPs) tend to be nondeterministic. Two-phase deterministic record-replay is an effective approach to resolve this problem. This paper proposes an efficient separate memory race record-replay (SMRR) based on point-to-point logging approach. During recording, SMRR logs predecessors and successors of memory races separately and uses an optimized log entry format for each log entry, achieving small log size and low bandwidth overhead. During replay, SMRR actively produces wakeup messages to trigger stalled successors in time, achieving low communication overhead and fast replay speed. The simulation shows that SMRR writes a small memory race log for SPLASH-2 and PARSEC workloads, and has good scalability in log size. More importantly, SMRR can achieve the lowest bandwidth overhead in the recording phase, and a replay speed within 1–18% of the native execution speed without record-replay. [Copyright &y& Elsevier]

Abstract: A challenge in virtual reality based laparoscopic cholecystectomy simulation is to construct a fast and accurate deformable gallbladder model. This paper proposed a multi-layered mass-spring model which can adapt well to the built-in accelerating algorithms in PhysX-Engine of Graphics Processing Unit (GPU). The gallbladder was first segmented from clinical Computed Tomography (CT) images. From the segmentation result, a surface mesh of a gallbladder was constructed. The inner layers of a mass-spring model were generated from the surface mesh based on the anatomical structure of gallbladder. We configured the parameters of the springs based on the biomechanical properties of gallbladder to ensure the reality of the deformation results. Preliminary experiments demonstrated that our model was able to achieve satisfactory results in terms of both visual perception and time performance. [Copyright &y& Elsevier]

Abstract: Embedded devices have gradually increased the demand for computing performance. In recent years, researches have focused on ways to maximize the performance of embedded multi-core SoC when the hardware consumption is very limited. This paper presents a new queueing network model and performance analysis method for embedded multi-core SoC based on task handling mechanism with priority. To calculate the blocking probability and queueing situation of the implementation for every executing core, finite capacity holding nodes are added to the queueing model, and an equivalent queueing network model is obtained. An adaptive load scheduling algorithm is designed, and the main scheduler is real-time scheduling by blocking and queueing the situation of each core. Common priority FIFO buffer, high-priority FIFO buffer queue, and semi-global FIFO buffer queue are a reasonable distribution. Finally, the approximate iterative algorithm is proposed for evaluating system performance. The experimental results indicate that the adaptive scheduling algorithm significantly improves the balance of task assignment. [Copyright &y& Elsevier]

Abstract: Simultaneous Multi-Threading (SMT) provides a technique to improve resource utilization ability by sharing key data-path components among multiple independent threads. When critical resources are shared by multiple threads, effective use of these resources proves to be the most important factor in fully exploiting the system potential. Transient behaviors of various threads in terms of their execution parallelism can easily affect utilization efficiency of these shared resources. To commit more resources to threads that are more active allows for better resource utilization and thus higher throughput. In this paper, we propose a real-time dynamic scheduler for the SMT which dispatches instructions from threads based on thread-activeness information gathered in real time and dynamically adjusts dispatching priorities among threads accordingly. An extensive simulation shows a significant gain in system throughput by this technique. The performance of the proposed dispatching technique is evaluated on different workload mixtures created based on instruction-level parallelism available in each thread. An average of 6.5% and maximum of 15% performance improvement is observed with the proposed dispatching technique. [Copyright &y& Elsevier]