Search results for: voltage reference
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 1627

Search results for: voltage reference

457 Using Electrical Impedance Tomography to Control a Robot

Authors: Shayan Rezvanigilkolaei, Shayesteh Vefaghnematollahi

Abstract:

Electrical impedance tomography is a non-invasive medical imaging technique suitable for medical applications. This paper describes an electrical impedance tomography device with the ability to navigate a robotic arm to manipulate a target object. The design of the device includes various hardware and software sections to perform medical imaging and control the robotic arm. In its hardware section an image is formed by 16 electrodes which are located around a container. This image is used to navigate a 3DOF robotic arm to reach the exact location of the target object. The data set to form the impedance imaging is obtained by having repeated current injections and voltage measurements between all electrode pairs. After performing the necessary calculations to obtain the impedance, information is transmitted to the computer. This data is fed and then executed in MATLAB which is interfaced with EIDORS (Electrical Impedance Tomography Reconstruction Software) to reconstruct the image based on the acquired data. In the next step, the coordinates of the center of the target object are calculated by image processing toolbox of MATLAB (IPT). Finally, these coordinates are used to calculate the angles of each joint of the robotic arm. The robotic arm moves to the desired tissue with the user command.

Keywords: Electrical impedance tomography, EIT, Surgeon robot, image processing of Electrical impedance tomography.

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456 Control of Grid Connected PMSG-Based Wind Turbine System with Back-To-Back Converter Topology Using Resonant Controller

Authors: Fekkak Bouazza, Menaa Mohamed, Loukriz Abdelhamid, Krim Mohamed L.

Abstract:

This paper presents modeling and control strategy for the grid connected wind turbine system based on Permanent Magnet Synchronous Generator (PMSG). The considered system is based on back-to-back converter topology. The Grid Side Converter (GSC) achieves the DC bus voltage control and unity power factor. The Machine Side Converter (MSC) assures the PMSG speed control. The PMSG is used as a variable speed generator and connected directly to the turbine without gearbox. The pitch angle control is not either considered in this study. Further, Optimal Tip Speed Ratio (OTSR) based MPPT control strategy is used to ensure the most energy efficiency whatever the wind speed variations. A filter (L) is put between the GSC and the grid to reduce current ripple and to improve the injected power quality. The proposed grid connected wind system is built under MATLAB/Simulink environment. The simulation results show the feasibility of the proposed topology and performance of its control strategies.

Keywords: Wind, grid, PMSG, MPPT, OTSR.

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455 The Decentralized Nonlinear Controller of Robot Manipulator with External Load Compensation

Authors: Sun Lim, Il-Kyun Jung

Abstract:

This paper describes a newly designed decentralized nonlinear control strategy to control a robot manipulator. Based on the concept of the nonlinear state feedback theory and decentralized concept is developed to improve the drawbacks in previous works concerned with complicate intelligent control and low cost effective sensor. The control methodology is derived in the sense of Lyapunov theorem so that the stability of the control system is guaranteed. The decentralized algorithm does not require other joint angle and velocity information. Individual Joint controller is implemented using a digital processor with nearly actuator to make it possible to achieve good dynamics and modular. Computer simulation result has been conducted to validate the effectiveness of the proposed control scheme under the occurrence of possible uncertainties and different reference trajectories. The merit of the proposed control system is indicated in comparison with a classical control system.

Keywords: Robot manipulator control, nonlinear controller, Lyapunov based stability, Interconnection compensation.

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454 Wind Diesel Hybrid System without Battery Energy Storage Using Imperialist Competitive Algorithm

Authors: H. Rezvani, A. Hekmati

Abstract:

Nowadays, the use of renewable energy sources has been increasingly great because of the cost increase and public demand for clean energy sources. One of the fastest growing sources is wind energy. In this paper, Wind Diesel Hybrid System (WDHS) comprising a Diesel Generator (DG), a Wind Turbine Generator (WTG), the Consumer Load, a Battery-based Energy Storage System (BESS), and a Dump Load (DL) is used. Voltage is controlled by Diesel Generator; the frequency is controlled by BESS and DL. The BESS elimination is an efficient way to reduce maintenance cost and increase the dynamic response. Simulation results with graphs for the frequency of Power System, active power, and the battery power are presented for load changes. The controlling parameters are optimized by using Imperialist Competitive Algorithm (ICA). The simulation results for the BESS/no BESS cases are compared. Results show that in no BESS case, the frequency control is more optimal than the BESS case by using ICA. 

Keywords: Renewable Energy, Wind Diesel System, Induction Generator, Energy Storage, Imperialist Competitive Algorithm.

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453 Design Application Procedures of 15 Storied 3D Reinforced Concrete Shear Wall-Frame Structure

Authors: H. Nikzad, S. Yoshitomi

Abstract:

This paper presents the design application and reinforcement detailing of 15 storied reinforced concrete shear wall-frame structure based on linear static analysis. Databases are generated for section sizes based on automated structural optimization method utilizing Active-set Algorithm in MATLAB platform. The design constraints of allowable section sizes, capacity criteria and seismic provisions for static loads, combination of gravity and lateral loads are checked and determined based on ASCE 7-10 documents and ACI 318-14 design provision. The result of this study illustrates the efficiency of proposed method, and is expected to provide a useful reference in designing of RC shear wall-frame structures.

Keywords: Structural optimization, linear static analysis, ETABS, MATLAB, RC shear wall-frame structures.

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452 Analysis of Electrocardiograph (ECG) Signal for the Detection of Abnormalities Using MATLAB

Authors: Durgesh Kumar Ojha, Monica Subashini

Abstract:

The proposed method is to study and analyze Electrocardiograph (ECG) waveform to detect abnormalities present with reference to P, Q, R and S peaks. The first phase includes the acquisition of real time ECG data. In the next phase, generation of signals followed by pre-processing. Thirdly, the procured ECG signal is subjected to feature extraction. The extracted features detect abnormal peaks present in the waveform Thus the normal and abnormal ECG signal could be differentiated based on the features extracted. The work is implemented in the most familiar multipurpose tool, MATLAB. This software efficiently uses algorithms and techniques for detection of any abnormalities present in the ECG signal. Proper utilization of MATLAB functions (both built-in and user defined) can lead us to work with ECG signals for processing and analysis in real time applications. The simulation would help in improving the accuracy and the hardware could be built conveniently.

Keywords: ECG Waveform, Peak Detection, Arrhythmia, Matlab.

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451 Temporal Analysis of Magnetic Nerve Stimulation–Towards Enhanced Systems via Virtualisation

Authors: Stefan M. Goetz, Thomas Weyh, Hans-Georg Herzog

Abstract:

The triumph of inductive neuro-stimulation since its rediscovery in the 1980s has been quite spectacular. In lots of branches ranging from clinical applications to basic research this system is absolutely indispensable. Nevertheless, the basic knowledge about the processes underlying the stimulation effect is still very rough and rarely refined in a quantitative way. This seems to be not only an inexcusable blank spot in biophysics and for stimulation prediction, but also a fundamental hindrance for technological progress. The already very sophisticated devices have reached a stage where further optimization requires better strategies than provided by simple linear membrane models of integrate-and-fire style. Addressing this problem for the first time, we suggest in the following text a way for virtual quantitative analysis of a stimulation system. Concomitantly, this ansatz seems to provide a route towards a better understanding by using nonlinear signal processing and taking the nerve as a filter that is adapted for neuronal magnetic stimulation. The model is compact and easy to adjust. The whole setup behaved very robustly during all performed tests. Exemplarily a recent innovative stimulator design known as cTMS is analyzed and dimensioned with this approach in the following. The results show hitherto unforeseen potentials.

Keywords: Theory of magnetic stimulation, inversion, optimization, high voltage oscillator, TMS, cTMS.

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450 Performance Analysis of a Series of Adaptive Filters in Non-Stationary Environment for Noise Cancelling Setup

Authors: Anam Rafique, Syed Sohail Ahmed

Abstract:

One of the essential components of much of DSP application is noise cancellation. Changes in real time signals are quite rapid and swift. In noise cancellation, a reference signal which is an approximation of noise signal (that corrupts the original information signal) is obtained and then subtracted from the noise bearing signal to obtain a noise free signal. This approximation of noise signal is obtained through adaptive filters which are self adjusting. As the changes in real time signals are abrupt, this needs adaptive algorithm that converges fast and is stable. Least mean square (LMS) and normalized LMS (NLMS) are two widely used algorithms because of their plainness in calculations and implementation. But their convergence rates are small. Adaptive averaging filters (AFA) are also used because they have high convergence, but they are less stable. This paper provides the comparative study of LMS and Normalized NLMS, AFA and new enhanced average adaptive (Average NLMS-ANLMS) filters for noise cancelling application using speech signals.

Keywords: AFA, ANLMS, LMS, NLMS.

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449 Transient Analysis of Central Region Void Fraction in a 3x3 Rod Bundle under Bubbly and Cap/Slug Flows

Authors: Ya-Chi Yu, Pei-Syuan Ruan, Shao-Wen Chen, Yu-Hsien Chang, Jin-Der Lee, Jong-Rong Wang, Chunkuan Shih

Abstract:

This study analyzed the transient signals of central region void fraction of air-water two-phase flow in a 3x3 rod bundle. Experimental tests were carried out utilizing a vertical rod bundle test section along with a set of air-water supply/flow control system, and the transient signals of the central region void fraction were collected through the electrical conductivity sensors as well as visualized via high speed photography. By converting the electric signals, transient void fraction can be obtained through the voltage ratios. With a fixed superficial water velocity (Jf=0.094 m/s), two different superficial air velocities (Jg=0.094 m/s and 0.236 m/s) were tested and presented, which were corresponding to the flow conditions of bubbly flows and cap/slug flows, respectively. The time averaged central region void fraction was obtained as 0.109-0.122 with 0.028 standard deviation for the selected bubbly flow and 0.188-0.221with 0.101 standard deviation for the selected cap/slug flow, respectively. Through Fast Fourier Transform (FFT) analysis, no clear frequency peak was found in bubbly flow, while two dominant frequencies were identified around 1.6 Hz and 2.5 Hz in the present cap/slug flow.

Keywords: Central region, rod bundles, transient void fraction, two-phase flow.

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448 A New Approach for Predicting and Optimizing Weld Bead Geometry in GMAW

Authors: Farhad Kolahan, Mehdi Heidari

Abstract:

Gas Metal Arc Welding (GMAW) processes is an important joining process widely used in metal fabrication industries. This paper addresses modeling and optimization of this technique using a set of experimental data and regression analysis. The set of experimental data has been used to assess the influence of GMAW process parameters in weld bead geometry. The process variables considered here include voltage (V); wire feed rate (F); torch Angle (A); welding speed (S) and nozzle-to-plate distance (D). The process output characteristics include weld bead height, width and penetration. The Taguchi method and regression modeling are used in order to establish the relationships between input and output parameters. The adequacy of the model is evaluated using analysis of variance (ANOVA) technique. In the next stage, the proposed model is embedded into a Simulated Annealing (SA) algorithm to optimize the GMAW process parameters. The objective is to determine a suitable set of process parameters that can produce desired bead geometry, considering the ranges of the process parameters. Computational results prove the effectiveness of the proposed model and optimization procedure.

Keywords: Weld Bead Geometry, GMAW welding, Processparameters Optimization, Modeling, SA algorithm

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447 Barriers and Strategies for Effective Communication between Parents and Children in the Family

Authors: Sadhana Ghnayiem

Abstract:

This article deals with the issue of effective communication between parents and children and its impact on the family in general and on the child in particular. The aim of this article is to provide information to parents, students, anyone interested in family communication between parents and children, and to provide them with tools to deal with barriers to communication in the family unit. The article presented a literature review of the importance of effective communication in the family, the definition of the concept of communication, and was a reference to factors and barriers in communication between parents and children leading to conflict destructive to the extent that barriers to effective communication in the family unit. At the end of the article, strategies were introduced to motivate children to behave appropriately, and to equip parents best to foster the healthy development of their children when they can create an atmosphere of effective communication. From the literature review, it's found that effective communication between parents and children prevents problematic behavior and helps children understand how to communicate effectively with others. Communication between parents and children is the cornerstone of a happy family life and is the basis for positive interactions between parents and children and increases self-esteem in children.

Keywords: Children, communication, conflict, family.

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446 Islamic Banking: An Ultimate Source of Financial Inclusion

Authors: Tasawar Nawaz

Abstract:

Promotion of socioeconomic justice through redistribution of wealth is one of the most salient features of Islamic economic system. Islamic financial institutions known as Islamic banks are used to implement this in practice under the guidelines of Islamic Shariah law. Islamic banking systems strive to promote and achieve financial inclusion among the society by offering interest-free banking and risk-sharing financing solutions. Shariah-compliant micro finance is one of the most popular financial instruments used by Islamic banks to enhance access to finance. Benevolent loan (or Qard-al-Hassanah) is one of the popular financial tools used by the Islamic banks to promote financial inclusion. This aspect of Islamic banking is empirically examined in this paper with specific reference to firm’s resources, largely defined here as intellectual capital. The paper finds that Islamic banks promote financial inclusion by exploiting available resources especially, the human intellectual capital.

Keywords: Financial inclusion, intellectual capital, Qard-al-Hassanah, Islamic banking.

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445 Neural Network Optimal Power Flow(NN-OPF) based on IPSO with Developed Load Cluster Method

Authors: Mat Syai'in, Adi Soeprijanto

Abstract:

An Optimal Power Flow based on Improved Particle Swarm Optimization (OPF-IPSO) with Generator Capability Curve Constraint is used by NN-OPF as a reference to get pattern of generator scheduling. There are three stages in Designing NN-OPF. The first stage is design of OPF-IPSO with generator capability curve constraint. The second stage is clustering load to specific range and calculating its index. The third stage is training NN-OPF using constructive back propagation method. In training process total load and load index used as input, and pattern of generator scheduling used as output. Data used in this paper is power system of Java-Bali. Software used in this simulation is MATLAB.

Keywords: Optimal Power Flow, Generator Capability Curve, Improved Particle Swarm Optimization, Neural Network

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444 Molding Properties of Cobalt-Chrome-Based Feedstocks Used in Low-Pressure Powder Injection Molding

Authors: Ehsan Gholami, Vincent Demers

Abstract:

Low-pressure powder injection molding is an emerging technology for cost-effectively producing complex shape metallic parts with the proper dimensional tolerances, either in high or in low production volumes. In this study, the molding properties of cobalt-chrome-based feedstocks were evaluated for use in a low-pressure powder injection molding process. The rheological properties of feedstock formulations were obtained by mixing metallic powder with a proprietary wax-based binder system. Rheological parameters such as reference viscosity, shear rate sensitivity index, and activation energy for viscous flow, were extracted from the viscosity profiles and introduced into the Weir model to calculate the moldability index. Feedstocks were experimentally injected into a spiral mold cavity to validate the injection performance calculated with the model.

Keywords: Binder, feedstock, moldability, powder injection molding, viscosity.

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443 Novel Intrinsic Conducting Polymer Current Limiting Device (CLD) for Surge Protection

Authors: Noor H Jabarullah

Abstract:

In the past many uneconomic solutions for limitation and interruption of short-circuit currents in low power applications have been introduced, especially polymer switch based on the positive temperature coefficient of resistance (PCTR) concept. However there are many limitations in the active material, which consists of conductive fillers. This paper presents a significantly improved and simplified approach that replaces the existing current limiters with faster switching elements. Its elegance lies in the remarkable simplicity and low-cost processes of producing the device using polyaniline (PANI) doped with methane-sulfonic acid (MSA). Samples characterized as lying in the metallic and critical regimes of metal insulator transition have been studied by means of electrical performance in the voltage range from 1V to 5 V under different environmental conditions. Moisture presence is shown to increase the resistivity and also improved its current limiting performance. Additionally, the device has also been studied for electrical resistivity in the temperature range 77 K-300 K. The temperature dependence of the electrical conductivity gives evidence for a transport mechanism based on variable range hopping in three dimensions.

Keywords: Conducting polymer, current limiter, intrinsic, moisture dependence, polyaniline, resettable, surge protection.

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442 A New H.264-Based Rate Control Algorithm for Stereoscopic Video Coding

Authors: Yi Liao, Wencheng Yang, Gangyi Jiang

Abstract:

According to investigating impact of complexity of stereoscopic frame pairs on stereoscopic video coding and transmission, a new rate control algorithm is presented. The proposed rate control algorithm is performed on three levels: stereoscopic group of pictures (SGOP) level, stereoscopic frame (SFrame) level and frame level. A temporal-spatial frame complexity model is firstly established, in the bits allocation stage, the frame complexity, position significance and reference property between the left and right frames are taken into account. Meanwhile, the target buffer is set according to the frame complexity. Experimental results show that the proposed method can efficiently control the bitrates, and it outperforms the fixed quantization parameter method from the rate distortion perspective, and average PSNR gain between rate-distortion curves (BDPSNR) is 0.21dB.

Keywords: Stereoscopic video coding, rate control, stereoscopic group of pictures, complexity of stereoscopic frame pairs.

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441 Spatial Econometric Approaches for Count Data: An Overview and New Directions

Authors: Paula Simões, Isabel Natário

Abstract:

This paper reviews a number of theoretical aspects for implementing an explicit spatial perspective in econometrics for modelling non-continuous data, in general, and count data, in particular. It provides an overview of the several spatial econometric approaches that are available to model data that are collected with reference to location in space, from the classical spatial econometrics approaches to the recent developments on spatial econometrics to model count data, in a Bayesian hierarchical setting. Considerable attention is paid to the inferential framework, necessary for structural consistent spatial econometric count models, incorporating spatial lag autocorrelation, to the corresponding estimation and testing procedures for different assumptions, to the constrains and implications embedded in the various specifications in the literature. This review combines insights from the classical spatial econometrics literature as well as from hierarchical modeling and analysis of spatial data, in order to look for new possible directions on the processing of count data, in a spatial hierarchical Bayesian econometric context.

Keywords: Spatial data analysis, spatial econometrics, Bayesian hierarchical models, count data.

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440 Synthesis of Iron-Modified Montmorillonite as Filler for Electrospun Nanocomposite Fibers

Authors: Khryslyn Araño, Dela Cruz, Michael Leo, Dela Pena, Eden May, Leslie Joy Diaz

Abstract:

Montmorillonite (MMT) is a very abundant clay mineral and is versatile such that it can be chemically or physically altered by changing the ions between the sheets of its layered structure. This clay mineral can be prepared into functional nanoparticles that can be used as fillers in other nanomaterials such as nanofibers to achieve special properties. In this study, two types of iron-modified MMT, Iron-MMT (FeMMT) and Zero Valent Iron-MMT (ZVIMMT) were synthesized via ion exchange technique. The modified clay was incorporated in polymer nanofibers which were produced using a process called electrospinning. ICP analysis confirmed that clay modification was successful where there is an observed decrease in the concentration of Na and an increase in the concentration of Fe after ion exchange. XRD analysis also confirmed that modification took place because of the changes in the d-spacing of Na-MMT from 11.5 Å to 13.6 Å and 12.6 Å after synthesis of FeMMT and ZVIMMT, respectively. SEM images of the electrospun nanofibers revealed that the ZVIMMT-filled fibers have a smaller average diameter than the FeMMT-filled fibers because of the lower resistance of the suspensions of the former to the elongation force from the applied electric field. The resistance to the electric field was measured by getting the bulk voltage of the suspensions.

Keywords: Electrospinning, nanofibers, montmorillonite.

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439 Design and Implementation of a Hybrid Fuzzy Controller for a High-Performance Induction

Authors: M. Zerikat, S. Chekroun

Abstract:

This paper proposes an effective algorithm approach to hybrid control systems combining fuzzy logic and conventional control techniques of controlling the speed of induction motor assumed to operate in high-performance drives environment. The introducing of fuzzy logic in the control systems helps to achieve good dynamical response, disturbance rejection and low sensibility to parameter variations and external influences. Some fundamentals of the fuzzy logic control are preliminary illustrated. The developed control algorithm is robust, efficient and simple. It also assures precise trajectory tracking with the prescribed dynamics. Experimental results have shown excellent tracking performance of the proposed control system, and have convincingly demonstrated the validity and the usefulness of the hybrid fuzzy controller in high-performance drives with parameter and load uncertainties. Satisfactory performance was observed for most reference tracks.

Keywords: Fuzzy controller, high-performance, inductionmotor, intelligent control, robustness.

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438 Cognitive Landscape of Values – Understanding the Information Contents of Mental Representations

Authors: J. Maksimainen

Abstract:

The values of managers and employees in organizations are phenomena that have captured the interest of researchers at large. Despite this attention, there continues to be a lack of agreement on what values are and how they influence individuals, or how they are constituted in individuals- mind. In this article content-based approach is presented as alternative reference frame for exploring values. In content-based approach human thinking in different contexts is set at the focal point. Differences in valuations can be explained through the information contents of mental representations. In addition to the information contents, attention is devoted to those cognitive processes through which mental representations of values are constructed. Such informational contents are in decisive role for understanding human behavior. By applying content-based analysis to an examination of values as mental representations, it is possible to reach a deeper to the motivational foundation of behaviors, such as decision making in organizational procedures, through understanding the structure and meanings of specific values at play.

Keywords: Content-based Approach, Mental Content, Mental Representations, Organizational values, Values

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437 Research of Dynamic Location Referencing Method Based On Intersection and Link Partition

Authors: Lv Wei-feng, Dai Xi, Zhu Tong-yu

Abstract:

Dynamic location referencing method is an important technology to shield map differences. These method references objects of the road network by utilizing condensed selection of its real-world geographic properties stored in a digital map database, which overcomes the defections existing in pre-coded location referencing methods. The high attributes completeness requirements and complicated reference point selection algorithm are the main problems of recent researches. Therefore, a dynamic location referencing algorithm combining intersection points selected at the extremities compulsively and road link points selected according to link partition principle was proposed. An experimental system based on this theory was implemented. The tests using Beijing digital map database showed satisfied results and thus verified the feasibility and practicability of this method.

Keywords: Dynamic location referencing, inter-sectionreferencing, road link partition, road link point referencing.

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436 Planar Tracking Control of an Underactuated Autonomous Underwater Vehicle

Authors: Santhakumar M., Asokan T.

Abstract:

This paper addresses the problem of trajectory tracking control of an underactuated autonomous underwater vehicle (AUV) in the horizontal plane. The underwater vehicle under consideration is not actuated in the sway direction, and the system matrices are not assumed to be diagonal and linear, as often found in the literature. In addition, the effect of constant bias of environmental disturbances is considered. Using backstepping techniques and the tracking error dynamics, the system states are stabilized by forcing the tracking errors to an arbitrarily small neighborhood of zero. The effectiveness of the proposed control method is demonstrated through numerical simulations. Simulations are carried out for an experimental vehicle for smooth, inertial, two dimensional (2D) reference trajectories such as constant velocity trajectory (a circle maneuver – constant yaw rate), and time varying velocity trajectory (a sinusoidal path – sinusoidal yaw rate).

Keywords: autonomous underwater vehicle, system matrices, tracking control, time – varying feed back, underactuated control.

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435 Principal Role and School Structure

Authors: Behnaz Mohajeran, Alireza Ghaleei

Abstract:

This main purpose of the study reported here was to investigate the extent to which the form of school governance (particularly decision-making) had an impact upon the effectiveness of the school with reference to parental involvement, planning and budgeting, professional development of teachers, school facilities and resources, and student outcomes. Particular attention was given to decision-making within the governance arrangements. The study was based on four case studies of high schools in New South Wales, Australia including one government school, one independent Christian community school, one independent Catholic school, and one Catholic systemic school. The focus of the research was principals, teachers, parents, and students of four schools with varying governance structures. To gain a greater insight into the issues, the researchers collected information by questionnaire, semi-structured interview, and review of school key documents. This study found that it was not so much structure but the centrality of the school Principal and the way that the Principal perceived his/her roles in relation to others that impacted most on school governance.

Keywords: governance structure, principal role, schooleffectiveness, stakeholder involvement

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434 The Capabilities Approach as a Future Alternative to Neoliberal Higher Education in the MENA Region

Authors: Ranya Elkhayat

Abstract:

This paper aims at offering a futures study for higher education in the Middle East. Paying special attention to the negative impacts of neoliberalism, the paper will demonstrate how higher education is now commodified, corporatized and how arts and humanities are eschewed in favor of science and technology. This conceptual paper argues against the neoliberal agenda and aims at providing an alternative exemplified in the Capabilities Approach with special reference to Martha Nussbaum’s theory. The paper is divided into four main parts: the current state of higher education under neoliberal values, a prediction of the conditions of higher education in the near future, the future of higher education using the theoretical framework of the Capabilities Approach, and finally, some areas of concern regarding the approach. The implications of the study demonstrate that Nussbaum’s Capabilities Approach will ensure that the values of education are preserved while avoiding the pitfalls of neoliberalism.

Keywords: Capabilities approach, education future, higher education, MENA.

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433 Modelling and Simulation of Cascaded H-Bridge Multilevel Single Source Inverter Using PSIM

Authors: Gaddafi S. Shehu, T. Yalcinoz, Abdullahi B. Kunya

Abstract:

Multilevel inverters such as flying capacitor, diodeclamped, and cascaded H-bridge inverters are very popular particularly in medium and high power applications. This paper focuses on a cascaded H-bridge module using a single direct current (DC) source in order to generate an 11-level output voltage. The noble approach reduces the number of switches and gate drivers, in comparison with a conventional method. The anticipated topology produces more accurate result with an isolation transformer at high switching frequency. Different modulation techniques can be used for the multilevel inverter, but this work features modulation techniques known as selective harmonic elimination (SHE).This modulation approach reduces the number of carriers with reduction in Switching Losses, Total Harmonic Distortion (THD), and thereby increasing Power Quality (PQ). Based on the simulation result obtained, it appears SHE has the ability to eliminate selected harmonics by chopping off the fundamental output component. The performance evaluation of the proposed cascaded multilevel inverter is performed using PSIM simulation package and THD of 0.94% is obtained.

Keywords: Cascaded H-bridge Multilevel Inverter, Power Quality, Selective Harmonic Elimination.

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432 Dose due the Incorporation of Radionuclides Using Teeth as Bioindicators nearby Caetité Uranium Mines

Authors: Viviane S. Guimarães, Ícaro M. M. Brasil, Simara S. Campos, Roseli F. Gennari, Márcia R. P. Attie, Susana O. Souza.

Abstract:

Uranium mining and processing in Brazil occur in a northeastern area near to Caetité-BA. Several Non-Governmental Organizations claim that uranium mining in this region is a pollutant causing health risks to the local population,but those in charge of the complex extraction and production of“yellow cake" for generating fuel to the nuclear power plants reject these allegations. This study aimed at identifying potential problems caused by mining to the population of Caetité. In this, work,the concentrations of 238U, 232Th and 40K radioisotopes in the teeth of the Caetité population were determined by ICP-MS. Teeth are used as bioindicators of incorporated radionuclides. Cumulative radiation doses in the skeleton were also determined. The concentration values were below 0.008 ppm, and annual effective dose due to radioisotopes are below to the reference values. Therefore, it is not possible to state that the mining process in Caetité increases pollution or radiation exposure in a meaningful way.

Keywords: bioindicators, radiation dose, radioisotopesincorporation, uranium.

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431 The First Ground Track Maintenance Manoeuvre of THEOS Spacecraft

Authors: Pornthep Navakitkanok, Ammarin Pimnoo, Seksan Jaturat

Abstract:

THEOS is the first earth observation spacecraft of Thailand which was launched on the 1st October 2008 and is currently operated by GISTDA. The transfer phase has been performed by Astrium Flight Dynamics team leading to a hand over to GISTDA teams starting mid-October 2008. The THEOS spacecraft-s orbit is LEO and has the same repetitivity (14+5/26) as the SPOT spacecraft, i.e. the same altitude of 822 km but it has a different mean local solar time (LST). Ground track maintenance manoeuvres are performed to maintain the ground track within a predefined control band around the reference ground track and the band is ±40 km for THEOS spacecraft. This paper presents the first ground track maintenance manoeuvre of THEOS spacecraft and the detailed results. In addition, it also includes one and a half year of operation as seen by GISTDA operators. It finally describes the foreseenable activities for the next orbit control manoeuvre (OCM) preparation.

Keywords: Orbit Control Manoeuvre, Ground Track Error, Local Solar Time Error, LEO, THEOS

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430 The Content Based Objective Metrics for Video Quality Evaluation

Authors: Michal Mardiak, Jaroslav Polec

Abstract:

In this paper we proposed comparison of four content based objective metrics with results of subjective tests from 80 video sequences. We also include two objective metrics VQM and SSIM to our comparison to serve as “reference” objective metrics because their pros and cons have already been published. Each of the video sequence was preprocessed by the region recognition algorithm and then the particular objective video quality metric were calculated i.e. mutual information, angular distance, moment of angle and normalized cross-correlation measure. The Pearson coefficient was calculated to express metrics relationship to accuracy of the model and the Spearman rank order correlation coefficient to represent the metrics relationship to monotonicity. The results show that model with the mutual information as objective metric provides best result and it is suitable for evaluating quality of video sequences.

Keywords: Objective quality metrics, mutual information, region recognition, content based metrics

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429 Fabrication of Carbon Doped TiO2 Nanotubes via In-situ Anodization of Ti-foil in Acidic Medium

Authors: Asma M. Milad, Mohammad B. Kassim, Wan R. Daud

Abstract:

Highly ordered TiO2 nanotube (TNT) arrays were fabricated onto a pre-treated titanium foil by anodic oxidation with a voltage of 20V in phosphoric acid/sodium fluoride electrolyte. A pretreatment of titanium foil involved washing with acetone, isopropanol, ethanol and deionized water. Carbon doped TiO2 nanotubes (C-TNT) was fabricated 'in-situ' with the same method in the presence of polyvinyl alcohol and urea as carbon sources. The affects of polyvinyl alcohol concentration and oxidation time on the composition, morphology and structure of the C-TN were studied by FE-SEM, EDX and XRD techniques. FESEM images of the nanotubes showed uniform arrays of C-TNTs. The density and microstructures of the nanotubes were greatly affected by the content of PVA. The introduction of the polyvinyl alcohol into the electrolyte increases the amount of C content inside TiO2 nanotube arrays uniformly. The influence of carbon content on the photo-current of C-TNT was investigated and the I-V profiles of the nanotubes were established. The preliminary results indicated that the 'in-situ' doping technique produced a superior quality nanotubes compared to post doping techniques.

Keywords: Anodization, photoelectrochemical cell, 'in-situ', post doping, thin film, and titania nanotube arrays.

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428 Determination of Chemical Oxygen Demand in Spent Caustic by Potentiometric Determination

Authors: Hamed Harrafi, Masoumeh Khedri, Karim Karaminejad

Abstract:

Measurement of the COD of a spent caustic solution involves firstly digestion of a test sample with dichromate solution and secondly measurement of dichromate remained by titration by ferrous ammonium sulfate [FAS] to an end point. In this paper we study by a potentiometric end point with Ag/AgCl reference electrode and gold rode electrode. The potentiometric end point is sharp and easily identified especially for the samples with high turbidity and color that other methods such as colorimetric in this type of sample do not result in high precision. Because interim of titration responds quickly to potential changes within the [Cr+6/Cr+3& Fe+2/Fe+3] solution producing stable readings that is lead to accurate COD measurement. Finally results are compared with data determined using colorimetric method for standard samples. It is shown that the potentiometric end point titration with gold rode electrode can be used with equal or better facility

Keywords: chemical oxygen demand, spent caustic and potentiometric determination

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