Abstract: We propose a new XOR based scheduling algorithm for network coding in cooperative local repair. The algorithm makes use of knowledge of the packets availability at neighboring nodes to improve the overall network throughput. In our proposed algorithm, we use network coding to determine which node should transmit and in which time slot (sequential MAC) that would provide the best improvement.
Abstract: We study the performance of differential space-time codes with linear constellation precoding (LCP) for orthogonal frequency division multiplexing (OFDM) cooperative networks over frequency selective channels. Through exploiting the unitary structure of the orthogonal STBCs, we design a low complexity differential STBC-LCP-OFDM receiver for cooperative networks. We assume the amplify-and-forward protocol and consider both single relay and multi-relay scenarios. Under the assumption of perfect power control for the relay terminal and high signal-to-noise ratio for the underlying links, our performance analysis demonstrates that the considered scheme is able to exploit fully the spatial diversity.
Abstract: Routing in Ad Hoc Networks is a critical issue. It must deal with the dynamic topology and lack of centralized operations guaranteeing the message delivery. In these networks, data messages might be dropped by malicious nodes, buffer overflows or even due to collisions. A technique to reduce the impact of the data messages discard in ad hoc networks is presented in this paper. This technique combines a Redundant Residue Number System and multipath routing. The Redundant Residue Number System allows a message to be split into n partial parts, and reconstructed using only t > n/2 parts. The proposed mechanism uses the Redundant Residue Number System to split data messages into n parts which are sent to the destination through disjoint routes using a multipath routing protocol. The multipath routing protocol is used to guarantee that the n parts of a message do not travel over a unique route from the source to the destination. In this way, the proposed technique can avoid malicious or congested nodes w
Abstract: In this paper, we try to monitor and optimize the productivity of network operations and management centers in a big telecommunication company. To achieve this goal, we apply linear programming and simulation techniques and propose a system architecture. Linear programming and simulation are most frequently used techniques in management science field. We apply these techniques to obtain the best staffing level of network operations and management centers and verify the result. We also propose a system architecture that implements the linear programming model in the real situation and monitor the productivity of network operations and management centers. This research will help to increase the competitiveness of a telecommunication company as well as other organizations by reducing the operating expenditure in today’s fierce competitive environment.
Abstract: Currently, we are working on the integration of the FHMIPv6/MPLS protocol to provide QoS in hybrids scenarios the quality of service values were obtained when a handover occurred and the results were satisfactory. In general terms, we can affirm that during a handover, not only metrics such as delay jitter and throughput improved but also the default quality level was maintained in the integrations performed. The results obtained allowed us to identify which integration protocols were the most suitable to ensure QoS in all IPv6/MPLS network. An architectures for new generation hybrid networks is proposal, In general, the coupling between the quality of service and mobility protocols mentioned before is an excellent option to provide QoS in wireless mobile networks and, especially, in the hybrids mobile networks.
Abstract: The aim of this investigation is to improve the performance of a basic microstrip antenna array using a tree structure patch supplied by electromagnetic coupling. The developed network which contains two subnets, a distribution subnet and a scanning subnet, is considered as a first step to design an adaptive microstrip antenna for UMTS use. The patch distribution structure used in this experiment allowed a great improvement of gain, directivity as well as the adaptation level of the studied array. The following work was realized in the laboratory signals, systems and components of FST-Fes, in colaboration with the Microwave Laboratory of the National Institute of Posts and Telecommunications of Rabat.
Abstract: We propose a method to improve traditional character-based PPM text compression algorithms. Consider a text file as a sequence of alternating words and non-words, the basic idea of our algorithm is to encode non-words and prefixes of words using character-based context models and encode suffixes of words using dictionary models. By using dictionary models, the algorithm can encode multiple characters as a whole, and thus enhance the compression efficiency. The advantages of the proposed algorithm are: 1) it does not require any text preprocessing; 2) it does not need any explicit codeword to identify switch between context and dictionary models; 3) it can be applied to any character-based PPM algorithms without incurring much additional computational cost. Test results show that significant improvements can be obtained over character-based PPM, especially in low order cases.
Abstract: Today it is very much essential to use renewable fuels for power generation and transport applications because of energy security, environmental concerns, foreign exchange savings and socio-economic issues. The new process technologies developed during the last years made it possible to produce biodiesel from different vegetable oils comparable in quality to that of fossil diesel fuels with added attractive advantages. The transesterification process is well-established and becoming increasingly important, but there remain considerable inefficiencies in existing transesterification processes. There is an imperative need to improve the existing biodiesel production methods from technological, economical and environmental viewpoint and to investigate alternative and innovative production processes. In view of this, the review is carried out on biodiesel production and this study mainly highlights the different techniques used in the production of biodiesel from different edible and non-edible oils, advantages and limitations of each technique, and the optimization conditions for each process. The emerging technologies which can be utilized in this field of research are also investigated.
Abstract: This paper proposes a new method to trace the transmission loss in deregulated power system by incorporating the Genetic Algorithm (GA) and Least Squares Support Vector Machine (LS-SVM). The idea is to use GA to find the optimal values of hyper-parameters of LS-SVM and adopts a supervised learning approach to train the LS-SVM model. The proportional sharing method (PSM) is proposed to trace the transmission loss at each transmission line which is then utilized as a teacher in the proposed hybrid technique called GA-SVM method. Based on load profile as inputs and PSM output for transmission loss allocation, the GA-SVM model is expected to learn which generators are responsible for transmission losses. In this paper, 4-bus system and IEEE 14-bus system are used to show the effectiveness of the proposed method.
Abstract: The model for the Software Industrialization in the Coffee Triangle seeks to establish a productive alternative to the growing of coffee. This model will permit the economic and social development of the so called “Coffee Triangle” located in the central part of Colombia in the Andean region, composed by the departments (states) of Caldas, QuindÃo and Risaralda. Through the consolidation of the software industry which is knowledge based, the lessons learned from the successful endogenous knowledge of the Coffee Triangle Region should be present in such a software model. Also successful International Software Models from other countries are being used to establish an international software industry in the Coffee Triangle of Colombia.
Abstract: Project-Based Learning (PBL) has become a necessity for the Moroccan higher education reform. PBL is an approach that transforms teaching from "teachers telling" to "students doing". However, implementing PBLs brings new challenges to higher education. In this paper, we present a set of Technology-enhanced Learning environments integrating the needed aspects in a synergetic way to fit well PBLs, especially in our context of use. The collaborative environments we developed, called respectively Smart-Project, Moulinette, Maroc Teleformation and Multi Agent Reporting System (MARS), were used to support PBL in the process of reform. In response to the challenges, the synergetic way in which our developed environments collaborated to provide interactive tracking data and semantic reports plays, in our sense, an important role in structuring and supporting effective PBL sessions.
Abstract: The process of ranking management information systems with the goal of finding the appropriate system to buy is complex. Measuring the importance of conflicting criteria by different stakeholders having varying interests can be challenging. Multi-criteria decision making (MCDM) offers promising solutions to this problem. The Analytic Hierarchy Process (AHP) and some of the ELECTRE methods are among the leading methods used in multi-criteria decision making. However, it is shown that these techniques suffer from rank irregularities which ultimately lead to inconsistent and unreliable decisions. This paper discusses the Routing Decision Support (RDS) method as a possible alternative to these techniques and the implementation of the method by way of a new software decision support system called Aki-Decisions. We examine the step by step process of how the Aki-Decisions software was used to make a recommendation for the selection of a Student Management System for the University College of Barbados.
Abstract: Magnetic Induction Tomography (MIT) is a new contactless imaging method for reconstructing the conductivity of objects. In MIT, one of main challenges is image reconstruction computation time, and the use of parallel processing is an effective means of reducing image reconstruction times to practical levels for monitoring applications. In this paper, we evaluated the comparative computational performance of three parallel processing accelerator options for MIT, namely (i) Graphics Processing Unit (GPU), (ii) Clearspeed AdvanceTM accelerator card, and (iii) multi-core processor PC, and discuss their advantages/disadvantages for application in MIT image reconstruction. The paper concentrates on parallelizing the finite difference (FD) algorithm, which is the most computationally demanding part of the forward model, and computation times for the implementation of this algorithm on each of the accelerators are given. The results show that the Clearspeed and quad-core accelerators provided similar perfor
Abstract: A novel BiCMOS voltage-to-voltage converter with logarithmic characteristics and very high accuracy is presented. The relationship between the emitter current and the base-emitter voltage in bipolar transistors is used to realize the logarithmic function. With 1.8 supply voltage, the total power consumption is less than 15.75 mW and an error of < -36dB is shown in the ADS simulations. Compared to the other method in the literature, very better accuracy in logarithm calculation is achieved. The proposed method can be used in arithmetical operation circuits like analog processors.
Abstract: In this work, the electrical modeling and simulation of phase shifter based on distributed CPW transmission lines structure is presented. It presents an analytical study followed by circuit simulation of the phase shifting, the insertion loss and the return loss of proposed phase shifter. The expression of phase shifting is obtained through a global ABCD matrix of 9 sections of proposed phase shifter then obtained by circuit simulation on Matlab. This study is compared with characterized phase shifter.
Abstract: Due to high speed computer networks, the use of digitally formatted data has increased many folds. The digital data can be duplicated and edited with great ease which has led to a need for effective copyright protection tools. The process of embedding additional data along with the digital audio, images and video is called digital watermarking. A number of watermarking techniques have been proposed in literature. This paper is a tutorial in general watermarking principles and focuses on describing various watermarking techniques.
Abstract: Resources assigned to virtual network are not optimal resources, which are caused by some scarce resources. To solve this problem, this paper proposes a novel virtual network mapping algorithm that can realize mapping cost minimizing, called CMVNMA, based on two characteristics of network virtualization environment, that is virtual network has lifecycle and substrate network resources are increased or decreased periodically. CMVNM includes virtual network mapping sub-algorithm (VNMsA) that can label virtual nodes and virtual links which are not allocated optimal resources, and heuristic migration sub-algorithm (HMsA) that can realize saved substrate resources maximization and migration cost minimization. Simulation results show that CMVNMA can save around 15% substrate network resources, and HMsA can use litter time to save the most substrate network resources than greedy migration algorithm (GMA) and random migration algorithm (RMA).
Abstract: This paper introduces a real-time tooth layers identification technique which is based on signal processing of
air-turbine dental handpiece. The technique will serve as an assistive tool in dental restoration procedures; where the tactile and visual senses of dentists are their only feedback sources, to minimize healthy tooth removal. The vibration of the dental handpiece is measured by two sensors i.e. accelerometer and Laser Doppler Vibrometer. The frequency analysis reveals clean and distinguishable peaks and there are no major differences between the sensors readings. It is found that the first vibration peak in the frequency spectrum of the handpiece corresponds to its angular velocity. This frequency is selected as the feature for the discrimination between enamel and dentin. A qualitative analysis is conducted on air-turbine handpieces to obtain and verify the practicality of our strategy for cutting material identification. The experimental results indicated that the angular velocity of an air-turbine handpiece is changed under different loads. It is shown that the angular velocity reduction matched to the pattern predicted by our qualitative study.
Finally, the air-turbine handpiece is tested on a human tooth to investigate the effect of tooth layers in the angular velocity at different supply pressures. The main focus of this analysis is on discrimination of enamel and dentin as the two major tooth components. It is shown that the technique can be expanded to cover other tooth layers as well. Our study shows distinct regions for enamel and dentin on pressure-velocity curves. These curves can accurately differentiate enamel and dentin in a known air pressure supply.
Abstract: Pervasive computing has become a very hot research field. In our previous work, we have proposed a system named UMP-Percomp, a Ubiquitous MultiProcessor-based Pipeline processing architecture to support high performance pervasive application development. So far we have implemented a prototype system to evaluate the performance of the architecture. However, the structure of the prototype system has some limitations: lack of scalability, inefficient resource allocation algorithm, and lack of flexibility for new kind of tasks. Hence we solve these problems and improve the current UMP system. We add a UDP server to each component to support scalability and component substitution. We also design a parallel algorithm to maximum the usage of PEs (Processing Elements), and we also consider the situation of lacking PEs suitable for requested tasks. Finally, we run extensive experiments on the new system to compare with the old system.
Abstract: New electronics for medical monitoring promise low-cost, maintenance-free, and lightweight devices which are critical in long-term medical measurements and in home-based tele-monitoring services. Operational Transconductance Amplifier (OTA) is a fundamental block of analog signal processing application particularly in Gm-C filter. A modified architecture of linearized subthreshold OTA for low-power, low-voltage, and low-frequency applications which incorporates better linearity and increased output impedance has been proposed in this paper. The OTA uses high output impedance low voltage current mirror to increase its impedance. The achieved open-loop DC gain is 71.49 dB at unity gain bandwidth (UGB) of 98.16 KHz. The OTA runs at power supply of 0.9 volt which makes OTA to consume power is 285.99 nanowatts. The circuit implementation has been done using standard 0.18 micron technology provided by TSMC on BSIM 3v3 level-53 model parameter and verified results through use of ELDO Simulator.
Abstract: With the sound mechanism of Source Address Validation Architecture (SAVA), every packet received and
forwarded in a trustworthy network has been ensured to hold an authenticated source IP address, which can prevent network attacks with spoofed source addresses. However, it is impossible to deploy SAVA all over the Internet in one night. In this paper, we investigate the SAVA mechanism from the point of routing for
trustworthy networks with partial deployments of SAVA nodes. We first describe and compare three different routing policies for trustworthy networks, and then propose a new routing algorithm, called Minimum Hop to First SAVA node algorithm (MHFS).
Extensive simulations show that MHFS can not only guarantee that each route for packets includes at least one SAVA node, but also achieve significant improvements in success probability for routing packets and resource utilization while considering the loop prevention and the load balance for SAVA nodes.
Abstract: In this paper, we analyze the impact of imperfect channel estimation on the performance of pilot symbol assisted modulation (PSAM) scheme used in a cooperative communication system with distributed space time block code (STBC) operating with amplify-and-forward (AaF) relaying protocol. The fading channel is modeled as both Rayleigh fading and cascaded Rayleigh fading, also known as double Rayleigh fading. We derive the correlation coefficient r between the channel gain and its erroneous estimate, due to the imperfect CSI at the receiver terminal; when the R®D link is either nonfading or fading. We present an expression for r in terms of Doppler frequency, number of pilot symbols and SNR. Our performance analysis demonstrates that the presence of fading in the R®D link manifests itself by introducing additional Doppler frequency terms in r . It also reveals that there are additional Doppler frequency terms in case of cascaded Rayleigh
channel compared to the conventional Rayleigh fading channel.
Furthermore, we derive a tight lower bound for the bit error rate (BER) of both channel models with channel estimation errors, in terms of cross-correlation coefficients. Simulation results are also presented to corroborate our analytical studies.
Abstract: Digital image and video in their raw form require an enormous amount of storage capacity. Considering the important role played by digital imaging and video in medical and health science, it is necessary to develop a system that produces high degree of compression while preserving critical image/video information. In this paper, we propose a sub-sample based hybrid DWT-DCT algorithm that performs the discrete cosine
transform on the discrete wavelet transform coefficient.
Simulations have been conducted on several medical and endoscopic images, and endoscopic videos. The results show that the proposed hybrid DWT-DCT algorithm performs much better than the standalone DWT, JPEG-based DCT, and Walsh-Hadamard transform algorithms in terms of peak signal to noise ratio and visual quality with a higher compression ratio. The new scheme reduces “false contouring” and “blocking artifacts”significantly. The rate distortion analysis shows that for a fixed level of distortion, the number of bits required to transmit the hybrid coefficients would be less than those required for other schemes.
Abstract: Unwanted feedback between the donor (receive) and coverage (service) antennas of a relay (repeater) are created by the radio echoes from the local scatters and direct path antenna isolation limitations. These radio echoes create interference not only in the incoming signal from the base station, but also cause instability in the repeater. In this paper, we present an interference cancellation system (ICS) for the multi-hop cellular networks. We propose a novel multiple-tap radio echo suppressor to give better performance. Our proposed architecture requires new taps and the complexity is greatly reduced. Interference cancellation ability of the ICS is confirmed using a test bench realized on a Xilinx Virtex-4 FPGA platform.
Abstract: This work presents a novel design of two-wheeled vehicles. The proposed design provides the vehicle with more flexibility in terms of the increased degrees of freedom which enable the vehicle to enlarge its working space. The additional translational degree of freedom (DOF), offered by the linear actuator, assists any attached payload to reach higher levels as and when required. The model of the system mimics the scenario of double inverted pendulum on a moving base. However, it is further complicated due to the addition of a one more (DOF). As adding more degrees of freedom to the system increases the degree of complexity, Lagrangian dynamic formulation is used, due to its relative simplicity, to derive the system dynamics. The new developed configurations is of great importance in various applications including self balance robots, wheelchairs on two wheels, stability analysis of multi segment gaits and multi links cranes etc. In order to maintain the system nonlinear characteristics, the system model is derived with the consideration of the joints friction based on the Coulomb friction model. An investigation is carried out on the impact of the joints damping on the stability of the system.
Abstract: The use of nanoscale structures in sensing applications has been heavily investigated in recent years, with many significant breakthroughs that suggest a bright future for the technology. Silicon nanowires have received particular attention for their use as sense elements because of their large surface areato-volume ratios and ability to be chemically altered to facilitate the binding of chemical or biological agents. The binding of these agents induces a conductance change in the wire, which can be monitored to detect the presence of trace amounts of an agent in a sample. The goal of the Addressable Internetworked Microscale Sensor (AIMS) system is to design a lab on a chip capable of detecting these small changes in conductance, and transmitting the data for analysis. The Complementary Metal Oxide Semiconductor (CMOS) integrated circuit is a 1.5mm by 1.5mm chip built in AMI C5F 0.5µm technology with a 4 × 4 array of nanowire sensors. A response time of 30 µs is measured with a tunability of 100kilo-Ohm to 100Mega-Ohm in nanowire resistance for sensitivity to external binding agents.
Abstract: Since the initial discovery of anomalous increases in the thermal conductivity of particle-fluid suspensions (nanofluids), they have become the topic of much research. Other potentially useful properties of nanofluids have also been studied extensively, yet our fundamental understanding of the mechanisms which create these exciting and promising properties is limited. This lack of understanding places limits on the applicability of nanofluids and our ability to accurately model them. As a consequence, further experimental and numerical research is needed that will help to develop better understanding of nanofluid flows and their heat transfer properties. One of the first theoretical investigations regarding the effective thermal conductivity of particle-fluid suspensions was conducted by Maxwell as early as 1873: Unfortunately, the resulting empirical expressionhas been found to have limited predictive capability, but since then, several other investigations have expanded on that original work with some success. While the initial experimentation on the effective thermal conductivity of nanoparticle suspension was not performeduntil the end of last century, other approximate empirical equations have been developed. In 2004, systematic surveys of experimental and modeling reviews revealed that most models were phenomenological in nature, and that they address the problems partially. That work also demonstrated that the effectiveness of nanofluids depended not only on the enhanced thermal conductivity, but also on other properties such as viscosity and specific heat. The current thinking is that we may have to apply the full Navier Stokes, energy and continuity equations in order to help explain flow property variations in microfluid flow, with heat transfer.
Abstract: Security assessment is a crucial process in the application deployment. The network layer plays an important role in the computer infrastructure. Network infrastructure generally consists of firewall, router, and switches etc. The vulnerabilities and technology gaps in the network assets may lead to serious problems in the security and application deployment. Here we study the risk assessment framework for a network layer for making the network layer more effective and secure. The study led to quantifying risk factor of a network layer.
Abstract: In this paper an optimized approach is presented to design & implement WCDMA based digital down converter for Software Defined Radios. The proposed DDC is designed using Park McClellan algorithm to achieve optimal filter order for hardware reduction. A computationally efficient polyphase decomposition structure is presented to enhance the speed and area efficiency. The embedded multipliers and LUTs of target FPGA have been efficiently utilized to enhance the system performance. The proposed DDC model is designed with Matlab, synthesized with Xilinx Synthesis Tool (XST) and implemented on Virtex-II Pro based xc2vp30-7ff896 FPGA device. The results show that proposed design can operate at a maximum frequency of 145.54 MHz by consuming 0.10313W power at 25° C junction temperature. The multiplier based FPGA has been used for hardware implementation to provide cost effective solution for SDR based wireless applications.
Abstract: This work carries out design and implementation of a PID control algorithm utilizing genetic algorithm as an optimization technique for a novel design of a two-wheeled vehicle with an extended rod. The vehicle design offers an additional feature to the conventional inverted pendulum on two wheels. The intermediate body (IB) of the vehicle is composed of two co-axial parts connected by a linear actuator and with a payload attached to the end of the upper part. The linear actuator allows the payload to move up and down along the IB of the vehicle. Considering the various positions, speeds and different sizes of a payload, carried by the vehicle, while maintaining the entire vehicle balanced is the main anxiety of the current study. Dynamic modeling of the system is based on utilizing Lagrangian formulation to drive the system equations of motion.
Abstract: As far as the system of two-wheeled machine is concerned, incorporating a linear actuator to the intermediate body (IB) of two-wheeled vehicles has not presented in literature before. This paper investigates development, modeling and control of a novel design of a two wheeled vehicle with additional mobility features allowing an attached payload to move vertically while maintaining the entire system balance condition. This work aims to develop and build a well designed two-wheeled vehicle with specific features. Certain mechanical issues are discussed in order to build a well designed mechanical prototype. The prototype is designed so as to be able to carry and move a payload in a vertical direction while maintaining a balance condition of the vehicle on two wheels. An approach for modeling the system to characterize its dynamic behavior is also presented. A control strategy is developed and implemented on the system in order to steer the vehicle to perform a certain wheels trajectory. Different wheel trajectory profiles are used to check the capability of the developed control scheme to tackle the control problem while maintaining the balance condition of the entire mechanism.
Abstract: This paper presents an efficient method to design & implement WCDMA based digital up converter for Software Radios. The Park McClellan algorithm has been proposed for optimal filter length to reduce hardware requirements. A computationally efficient polyphase decomposition structure is also proposed to optimize both speed and area. The embedded multipliers and LUTs of target FPGA are efficiently utilized to enhance the system performance. The proposed DUC has been designed with Matlab, synthesized with Xilinx Synthesis Tool (XST) and implemented on Virtex-II Pro based xc2vp30-7ff896 FPGA device. The developed DUC can operate at a maximum frequency of 136.37 MHz by consuming 0.10313W power at 25° C junction temperature. The proposed design has been implemented on multiplier based target FPGA to provide cost effective solution for SDR based wireless applications.
Abstract: Cooperating nodes in wireless networks need to be power-efficient because once they deployed, as in sensor
networks, they might not be recharged or replaced. The choice of relaying technique, therefore, becomes a crucial design parameter. Our work provides a detailed comparative performance analysis of amplify-and-forward and zeroforcing relaying. Our results give valuable insights into the robustness of these two common relaying techniques under different assumptions on power constraints and channel conditions and can be used as a practical guideline in the choice of relaying techniques.
