Search results for: Frequency regulation

Authors: Leila Motamed-Jahromi, Mohsen Hatami, Alireza Keshavarz

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This research aims at obtaining the equations of pulse propagation in nonlinear plasmonic waveguides created with As₂S₃ chalcogenide materials. Via utilizing Helmholtz equation and first-order perturbation theory, two components of electric field are determined within frequency domain. Afterwards, the equations are formulated in time domain. The obtained equations include two coupled differential equations that considers nonlinear dispersion.

Keywords: Nonlinear optics, propagation equation, plasmonic waveguide.

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Authors: Batel Noureddine, Mehenni Mohamed, Kouadik Smain

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In a transcutanious inductive coupling of a biomedical implant, a new formula is given for the study of the Radio Frequency power attenuation by the biological tissue. The loss of the signal power is related to its interaction with the biological tissue and the composition of this one. A confrontation with the practical measurements done with a synthetic muscle into a Faraday cage, allowed a checking of the obtained theoretical results. The supply/data transfer systems used in the case of biomedical implants, can be well dimensioned by taking in account this type of power attenuation.

Keywords: Biological tissue, coupled coils, implanted device, power attenuation.

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Authors: Young-Dal Kim, Jae-Myung Shim, Woo-Yong Park, Sung-joong Kim, Dong Seok Hyun, Dae-Dong Lee

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The most common cause of power transformer failures is mechanical defect brought about by excessive vibration, which is formed by the combination of multiples of a frequency of 120 Hz. In this paper, the types of mechanical exciting forces applied to the power transformer were classified, and the mechanical damage mechanism of the power transformer was identified using the vibration transfer route to the machine or structure. The general effects of 120 Hz-vibration on the enclosure, bushing, Buchholz relay, pressure release valve and tap changer of the transformer were also examined.

Keywords: Structure-Vibration, Transformer.

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Authors: Long Kim Vu, Ban Dang Nguyen

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In this paper, the finite element method (FEM) is utilized to simulate the comprehensive process including tightening, releasing and self-loosening of a bolt joint under transverse vibration. Following to the accurate geometry of helical threads, an absolutely hexahedral meshing is implemented. The accuracy of simulation process is verified and validated by comparison with the experimental results on clamping force-vibration relationship, which shows the sufficient correlation. Further analysis with different amplitude and frequency of transverse vibration is done to determine the dominant factor inducing the failure.

Keywords: Bolt self-loosening, contact state, FEM, transverse vibration.

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Authors: Bhaba Priyo Das, Neville Watson, Yonghe Liu

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In recent years Operational Transconductance Amplifier based high frequency integrated circuits, filters and systems have been widely investigated. The usefulness of OTAs over conventional OP-Amps in the design of both first order and second order active filters are well documented. This paper discusses some of the tunability issues using the Matlab/Simulink® software which are previously unreported for any commercial OTA. Using the simulation results two first order voltage controlled all pass filters with phase tuning capability are proposed.

Keywords: All pass filter, Operational Transconductance Amplifier, Simulation.

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Authors: Payam Foroutan Yekta

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The formation of theatre in ancient Greece and the different reasons and arguments about it are still left as an interesting case of discussion, and the origin of the Greek drama is usually sought in the Dionysus Festival. One fundamental element for the transformation of ritual into theatre was the establishment of theatre or places specifically used for performing Greek drama. Despite the theories of social Darwinists in the field of theatre historiography, the present study takes as its point of departure the hypothesis that the procedure of the transformation of Dionysus rituals to theatre has not been an evolutionary one. Our arguments will be based on Michel Foucault’s theory in his seminal book Discipline and Punish, where he holds “power” to be always aiming at the regulation of formless and unpredictable masses in order to predict their movements and behaviours. Thus, it could be argued that by founding theatra, in less than two centuries, Athens’s political system has transformed the primitive, violent and chaotic Dionysus rituals, turning them into theatre in order to control the society as much as possible.

Keywords: Dionysus Rituals, Greek Drama, Theatron, Michel Foucault, Discipline and Punish, Political System.

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Authors: Morteza Fathipour, Seyed Nasrolah Anousheh, Kaveh Ghiafeh Davoudi, Vala Fathipour

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A device analysis of the photoconductive semiconductor switch is carried out to investigate distribution of electric field and carrier concentrations as well as the current density distribution. The operation of this device was then investigated as a switch operating in X band. It is shown that despite the presence of symmetry geometry, switch current density of the on-state steady state mode is distributed asymmetrically throughout the device.

Keywords: Band X, Gallium-Arsenide, Mixed mode, PCSS, Photoconductivity.

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Authors: Slavka Zeković

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A preliminary evaluation of the urban land system is presented in the article together with the instruments of land policy in Serbia. The main reason for the analysis is demand for definition of reform framework for urban land management in Serbia in the period of transition towards market-led system. It is concluded that due to the limitations of the current regulation it will be impossible in the future to apply market principles in the urban land policy (supply and demand of land, land capitalization, investment efficiency, et al.). Based on the estimation that the urban land system and land policy are key factors of competitiveness between regions and towns in Serbia, it is necessary to initiate changes in this field. There are indicated on an option of privatization of urban public land and possible establishment of leasehold land. A comparative analysis of the possibilities of the reform urban land system in Serbia has been carried out in relation to two approaches of market systems: (a) with dominant private ownership of urban land (neo/liberal approach) and (b) with dominant public ownership of urban land (system of leasehold)whose findings can be a basis for further study of the new system in Serbia.. The attanied results are part of studies matter for the making of Strategy of territorial development of Serbia.

Keywords: Urban Land System, Urban Land Management, Instruments of Land Policy, Evaluation, Market.

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Authors: Indradip Banerjee, Souvik Bhattacharyya, Gautam Sanyal

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In this paper, an approach is presented to investigate the performance of Pixel Factor Mapping (PFM) and Extended PMM (Pixel Mapping Method) through the qualitative and quantitative approach. These methods are tested against a number of well-known image similarity metrics and statistical distribution techniques. The PFM has been performed in spatial domain as well as frequency domain and the Extended PMM has also been performed in spatial domain through large set of images available in the internet.

Keywords: Qualitative, quantitative, PFM, EXTENDED PMM.

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Authors: O. P. Sharma, V. Janyani, S. Sancheti

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Data rate, tolerable bit error rate or frame error rate and range & coverage are the key performance requirement of a communication link. In this paper performance of MFSK link is analyzed in terms of bit error rate, number of errors and total number of data processed. In the communication link model proposed, which is implemented using MATLAB block set, an improvement in BER is observed. Different parameters which effects and enables to keep BER low in M-ary communication system are also identified.

Keywords: Additive White Gaussian Noise (AWGN), Bit Error Rate (BER), Frequency Shift Keying (FSK), Orthogonal Signaling.

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Authors: Ebru Belkıs Kamanlıoğlu, Cem Güzeloğlu

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As the new industrial revolution advances in the nanotechnology have been followed with interest throughout the world and also in Turkey. Media has an important role in conveying these advances to public, rising public awareness and creating attitudes related to nanotechnology. As well as representing how a subject is treated, media frames determine how public think about this subject. In literature definite frames related to nanoscience and nanotechnology such as process, regulation, conflict and risks were mentioned in studies focusing different countries. So how nanotechnology news is treated by which frames and in which news categories in Turkey as a one of developing countries? In this study examining different variables about nanotechnology that affect public attitudes such as category, frame, story tone, source in Turkish media via framing analysis developed in agenda setting studies was aimed. In the analysis data between 2005 and 2009 obtained from the first five national newspapers with wide circulation in Turkey will be used. In this study the direction of the media about nanotechnology, in which frames nanotechnologic advances brought to agenda were reported as news, and sectoral, legal, economic and social scenes reflected by these frames to public related to nanotechnology in Turkey were planned.

Keywords: Agenda, frames, media, nanotechnology, Turkey.

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Authors: Yanting Cao, Kazumitsu Nawata

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As smartphones are continually upgrading, their software and hardware are getting smarter, so the smartphone-based human activity recognition will be described more refined, complex and detailed. In this context, we analyzed a set of experimental data, obtained by observing and measuring 30 volunteers with six activities of daily living (ADL). Due to the large sample size, especially a 561-feature vector with time and frequency domain variables, cleaning these intractable features and training a proper model become extremely challenging. After a series of feature selection and parameters adjustments, a well-performed SVM classifier has been trained. 

Keywords: smart sensors, human activity recognition, artificial intelligence, SVM

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Authors: M. D. Prokhorov, V. I. Ponomarenko, A. S. Karavaev, A. R. Kiselev, V. I. Gridnev

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Synchronization between the slow oscillations of heart rate and blood pressure having in humans a basic frequency close to 0.1 Hz is investigated. A method is proposed for quantitative estimation of synchronization between these oscillating processes based on calculation of relative time of phase synchronization of oscillations. It is shown that healthy subjects exhibit in average substantially longer epochs of synchronization between the slow oscillations in heart rate and blood pressure than patients after acute myocardial infarction

Keywords: Cardiovascular system, slow oscillating processes, synchronization.

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Authors: Adam Niewiadomski

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The research objective of the project and article “European Ecological Network Natura 2000 – opportunities and threats” Natura 2000 sites constitute a form of environmental protection, several legal problems are likely to result. Most controversially, certain sites will be subject to two regimes of protection: as national parks and as Natura 2000 sites. This dualism of the legal regulation makes it difficult to perform certain legal obligations related to the regimes envisaged under each form of environmental protection. Which regime and which obligations resulting from the particular form of environmental protection have priority and should prevail? What should be done if these obligations are contradictory? Furthermore, an institutional problem consists in that no public administration authority has the power to resolve legal conflicts concerning the application of a particular regime on a given site. There are also no criteria to decide priority and superiority of one form of environmental protection over the other. Which regulations are more important, those that pertain to national parks or to Natura 2000 sites? In the light of the current regulations, it is impossible to give a decisive answer to these questions. The internal hierarchy of forms of environmental protection has not been determined, and all such forms should be treated equally.

Keywords: Natura 2000, European Ecological Network.

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Authors: R. Balamurugan, A. M. Natarajan, K. Premalatha

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Microarray gene expression data play a vital in biological processes, gene regulation and disease mechanism. Biclustering in gene expression data is a subset of the genes indicating consistent patterns under the subset of the conditions. Finding a biclustering is an optimization problem. In recent years, swarm intelligence techniques are popular due to the fact that many real-world problems are increasingly large, complex and dynamic. By reasons of the size and complexity of the problems, it is necessary to find an optimization technique whose efficiency is measured by finding the near optimal solution within a reasonable amount of time. In this paper, the algorithmic concepts of the Particle Swarm Optimization (PSO), Shuffled Frog Leaping (SFL) and Cuckoo Search (CS) algorithms have been analyzed for the four benchmark gene expression dataset. The experiment results show that CS outperforms PSO and SFL for 3 datasets and SFL give better performance in one dataset. Also this work determines the biological relevance of the biclusters with Gene Ontology in terms of function, process and component.

Keywords: Particle swarm optimization, Shuffled frog leaping, Cuckoo search, biclustering, gene expression data.

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Authors: C. Kocatepe, E. Taslak, C. F. Kumru, O. Arıkan

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While choosing insulating oil, characteristic features such as thermal cooling, endurance, efficiency and being environment-friendly should be considered. Mineral oils are referred as petroleum-based oil. In this study, vegetable oils investigated as an alternative insulating liquid to mineral oil. Dissipation factor, breakdown voltage, relative dielectric constant and resistivity changes with the frequency and voltage of mineral, rapeseed and nut oils were measured. Experimental studies were performed according to ASTM D924 and IEC 60156 standards.

Keywords: Breakdown voltage, dielectric dissipation factor, mineral oil, vegetable oils.

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Authors: S. Summart, C. Saetiaw, T. Thosdeekoraphat, C. Thongsopa

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This article presents new current-mode oscillator circuits using CDTAs which is designed from block diagram. The proposed circuits consist of two CDTAs and two grounded capacitors. The condition of oscillation and the frequency of oscillation can be adjusted by electronic method. The circuits have high output impedance and use only grounded capacitors without any external resistor which is very appropriate to future development into an integrated circuit. The results of PSPICE simulation program are corresponding to the theoretical analysis.

Keywords: Current-mode, Quadrature Oscillator, Block Diagram, CDTA.

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Authors: Adel Hamad Rafa

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This paper, proposes a control system for use with microgrid consiste of  multiple small scale embedded generation networks (SSEG networks) connected to the 33kV distribution network. The proposed controller controls power flow in the grid-connected mode of operation, enables voltage and frequency control when the SSEG networks are islanded, and resynchronises the SSEG networks with the utility before reconnecting them. The performance of the proposed controller has been tested in simulations using PSCAD.

Keywords: Microgrid, Small scale embedded generation, island mode, resynchronisation.

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Authors: Abolfazl Jalilvand, Mohammad Reza Feyzi, Sohrab Khanmohammad, Mohammad Bagher Bana Sharifian, Ali Sajjadi

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Nowadays the control of stator voltage at a constant frequency is one of the traditional and low expense methods in order to control the speed of induction motors near its nominal speed. The torque of induction motor is a nonlinear function of the firing angle, phase angle and speed. In this paper the speed control of induction motor regarding various load torque and under different conditions will be investigated based on a fuzzy controller with inverse training.

Keywords: Three phase induction motor, AC converter, speedcontrol, fuzzy control.

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Authors: Sylvain Chardon, Timotéo Payre, Hugo Grardel, Yann Quentel, Mathieu Thomachot, Gérald Aigouy, Frank Claeyssen

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With the increasing digitalization of society, access to data has become vital and strategic for individuals and nations. In this context, the number of satellite constellation projects is growing drastically worldwide and is a next-generation challenge of the New Space industry. So far, existing satellite constellations have been using radio frequencies (RF) for satellite-to-ground communications, inter-satellite communications, and feeder link communication. However, RF has several limitations, such as limited bandwidth and low protection level. To address these limitations, space optical communication will be the new trend, addressing both very high-speed and secured encrypted communication. Fast Steering Mirrors (FSM) are key components used in optical communication as well as space imagery and for a large field of functions such as Point Ahead Mechanisms (PAM), Raster Scanning, Beam Steering Mirrors (BSM), Fine Pointing Mechanisms (FPM) and Line of Sight stabilization (LOS). The main challenges of space FSM development for optical communication are to propose both a technology and a supply chain relevant for high quantities New Space approach, which requires secured connectivity for high-speed internet, Earth planet observation and monitoring, and mobility applications. CTEC proposes a mini-FSM technology offering a stroke of +/-6 mrad and a resonant frequency of 1700 Hz, with a mass of 50 g. This FSM mechanism is a good candidate for giant constellations and all applications on board NanoSats and CubeSats, featuring a very high level of miniaturization and optimized for New Space high quantities cost efficiency. The use of piezo actuators offers a high resonance frequency for optimal control, with almost zero power consumption in step and stay pointing, and with very high-reliability figures > 0,995 demonstrated over years of recurrent manufacturing for Optronics applications at CTEC.

Keywords: Fast steering mirror, feeder link, line of sight stabilization, optical communication, pointing ahead mechanism, raster scan.

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Authors: A. Ujunwa, P. O. Salami, A. H. Umar

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The recommendation of the committee on corporate governance for public companies in Nigeria, that the position of the CEO be separated from board chair has generated serious debate among scholars and practitioners. They have questioned the appropriateness of implementing corporate governance model that is based on Anglo-Saxon agency problem characterized by dispersed ownership structure; where markets for corporate control, legal regulation, and contractual incentives are the key governance mechanisms. This paper strives to resolve the argument by adopting an institutional perspective in testing the agency theory on board duality. The study developed a theoretical and empirical model to better understand how ownership structure influences agency conflict and how such affects firm performance. Hence, the study examines the relationship between CEO duality and firm performance using two institutional ownership structures – dispersed ownership and concentrated ownership structures. The empirical results show that CEO duality is negatively correlated with firm performance in Nigeria irrespective of the firm-s ownership structure. The findings give credence to the recommendation of the Peterside Commission on the need to separate the position of CEO from board chair.

Keywords: Corporate Governance, CEO-Duality, Firm Performance.

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Authors: Yi He, Nutdechatorn Puangngernmak, Suramate Chalermwisutkul

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Microwave heating process has been developed about sixty years while measurement system has also progressed. Because of irradiation of high frequency of microwave, researchers have been utilized many costly technical instrument measuring parameters to evaluate the performance of microwave heating system. Therefore, this paper is intended to present an easier and feasible efficiency measurement method. It can help inspecting efficiency of microwave heating system with good accuracy, while the method can also give reference to optimizing procedure for microwave heating system for various load material

Keywords: measurement, microwave heating system, systemic power efficiency

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Authors: Zuzana Dideková, Beata Mikovičová

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Characterization of radio communication signals aims at automatic recognition of different characteristics of radio signals in order to detect their modulation type, the central frequency, and the level. Our purpose is to apply techniques used in image processing in order to extract pertinent characteristics. To the single analysis, we add several rules for checking the consistency of hypotheses using fuzzy logic. This allows taking into account ambiguity and uncertainty that may remain after the extraction of individual characteristics. The aim is to improve the process of radio communications characterization.

Keywords: fuzzy classification, fuzzy inference system, radio communication signals, telecommunications

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Authors: K.Amrithavarshini, S.Chandrachudeswaran

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This paper presents an idea to improve the efficiency of security checks in airports through the active tracking and monitoring of passengers and staff using OFDM modulation technique and Finger print authentication. The details of the passenger are multiplexed using OFDM .To authenticate the passenger, the fingerprint along with important identification information is collected. The details of the passenger can be transmitted after necessary modulation, and received using various transceivers placed within the premises of the airport, and checked at the appropriate check points, thereby increasing the efficiency of checking. OFDM has been employed for spectral efficiency.

Keywords: Orthogonal Frequency Division Multiplexing, FFT Algorithm, Fingerprint Authentication, Airport Security

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Authors: T. Damak, S. Houidi, M. A. Ben Ayed, N. Masmoudi

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The Versatile Video Coding standard (VVC) is actually under development by the Joint Video Exploration Team (or JVET). An Adaptive Multiple Transforms (AMT) approach was announced. It is based on different transform modules that provided an efficient coding. However, the AMT solution raises several issues especially regarding the complexity of the selected set of transforms. This can be an important issue, particularly for a future industrial adoption. This paper proposed an efficient hardware implementation of the most used transform in AMT approach: the DCT II. The developed circuit is adapted to different block sizes and can reach a minimum frequency of 192 MHz allowing an optimized execution time.

Keywords: AMT, DCT II, hardware, transform, VVC.

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Authors: Cheng-Chung Yang, Jr-Ming Miao, Fuh-Lin Lih, Tsung-Lung Liu, Ming-Hui Ho

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The operation performance of a valveless micro-pump is strongly dependent on the shape of connected nozzle/diffuser and Reynolds number. The aims of present work are to compare the performance curves of micropump with the original straight nozzle/diffuser and contoured nozzle/diffuser under different back pressure conditions. The tested valveless micropumps are assembled of five pieces of patterned PMMA plates with hot-embracing technique. The structures of central chamber, the inlet/outlet reservoirs and the connected nozzle/diffuser are fabricated with laser cutting machine. The micropump is actuated with circular-type PZT film embraced on the bottom of central chamber. The deformation of PZT membrane with various input voltages is measured with a displacement laser probe. A simple testing facility is also constructed to evaluate the performance curves for comparison. In order to observe the evaluation of low Reynolds number multiple vortex flow patterns within the micropump during suction and pumping modes, the unsteady, incompressible laminar three-dimensional Reynolds-averaged Navier-Stokes equations are solved. The working fluid is DI water with constant thermo-physical properties. The oscillating behavior of PZT film is modeled with the moving boundary wall in way of UDF program. With the dynamic mesh method, the instants pressure and velocity fields are obtained and discussed.Results indicated that the volume flow rate is not monotony increased with the oscillating frequency of PZT film, regardless of the shapes of nozzle/diffuser. The present micropump can generate the maximum volume flow rate of 13.53 ml/min when the operation frequency is 64Hz and the input voltage is 140 volts. The micropump with contoured nozzle/diffuser can provide 7ml/min flow rate even when the back pressure is up to 400 mm-H2O. CFD results revealed that the flow central chamber was occupied with multiple pairs of counter-rotating vortices during suction and pumping modes. The net volume flow rate over a complete oscillating periodic of PZT

Keywords: valveless micropump、PZT diagraph、contoured nozzle/diffuser、vortex flow.

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Authors: F. Abdul Majeed, H. Karki, Y. Abdel Magid, M. Karkoub

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This paper analyses the non linear properties exhibited by a drill string system under various un balanced mass conditions. The drill string is affected by continuous friction in the form of drill bit and well bore hole interactions. This paper proves the origin of limit cycling and increase of non linearity with increase in speed of the drilling in the presence of friction. The spectrum of the frequency response is also studied to detect the presence of vibration abnormalities arising during the drilling process.

Keywords: Drill strings, Nonlinear, Spectrum analysis, Unbalanced mass

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Authors: Cheima Ben Soltane, Ittansa Yonas Kelbesa

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Speaker Identification (SI) is the task of establishing identity of an individual based on his/her voice characteristics. The SI task is typically achieved by two-stage signal processing: training and testing. The training process calculates speaker specific feature parameters from the speech and generates speaker models accordingly. In the testing phase, speech samples from unknown speakers are compared with the models and classified. Even though performance of speaker identification systems has improved due to recent advances in speech processing techniques, there is still need of improvement. In this paper, a Closed-Set Tex-Independent Speaker Identification System (CISI) based on a Multiple Classifier System (MCS) is proposed, using Mel Frequency Cepstrum Coefficient (MFCC) as feature extraction and suitable combination of vector quantization (VQ) and Gaussian Mixture Model (GMM) together with Expectation Maximization algorithm (EM) for speaker modeling. The use of Voice Activity Detector (VAD) with a hybrid approach based on Short Time Energy (STE) and Statistical Modeling of Background Noise in the pre-processing step of the feature extraction yields a better and more robust automatic speaker identification system. Also investigation of Linde-Buzo-Gray (LBG) clustering algorithm for initialization of GMM, for estimating the underlying parameters, in the EM step improved the convergence rate and systems performance. It also uses relative index as confidence measures in case of contradiction in identification process by GMM and VQ as well. Simulation results carried out on voxforge.org speech database using MATLAB highlight the efficacy of the proposed method compared to earlier work.

Keywords: Feature Extraction, Speaker Modeling, Feature Matching, Mel Frequency Cepstrum Coefficient (MFCC), Gaussian mixture model (GMM), Vector Quantization (VQ), Linde-Buzo-Gray (LBG), Expectation Maximization (EM), pre-processing, Voice Activity Detection (VAD), Short Time Energy (STE), Background Noise Statistical Modeling, Closed-Set Tex-Independent Speaker Identification System (CISI).

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Authors: S. Raja Ratna, R. Ravi

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Wireless networks are built upon the open shared medium which makes easy for attackers to conduct malicious activities. Jamming is one of the most serious security threats to information economy and it must be dealt efficiently. Jammer prevents legitimate data to reach the receiver side and also it seriously degrades the network performance. The objective of this paper is to provide a general overview of jamming in wireless network. It covers relevant works, different jamming techniques, various types of jammers and typical prevention techniques. Challenges associated with comparing several anti-jamming techniques are also highlighted.

Keywords: Channel, Cryptography, Frequency, Jamming, Legitimate, Security, Wavelength.

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Authors: Safdar Tanweer, Abdul Mobin, Afshar Alam

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The performance and analysis of speech recognition system is illustrated in this paper. An approach to recognize the English word corresponding to digit (0-9) spoken by 2 different speakers is captured in noise free environment. For feature extraction, speech Mel frequency cepstral coefficients (MFCC) has been used which gives a set of feature vectors from recorded speech samples. Neural network model is used to enhance the recognition performance. Feed forward neural network with back propagation algorithm model is used. However other speech recognition techniques such as HMM, DTW exist. All experiments are carried out on Matlab.

Keywords: Speech Recognition, MFCC, Neural Network, classifier.

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