فهرست مطالب

Engineering - Volume:26 Issue: 11, Nov 2013

International Journal of Engineering
Volume:26 Issue: 11, Nov 2013

  • IJE TRANSACTIONS B: Applications
  • تاریخ انتشار: 1392/07/03
  • تعداد عناوین: 15
|
  • H. Hassanpour, A. Rostami Ghadi Pages 1267-1274
    In this paper, a new approach is presented for improving image quality. It provides a new outlook on how to apply the enhancment methods on images. Image enhancement techniques may deal with the illumination, resolution, or distribution of pixels values. Issues such as the illumination of the scene and reflectance of objects affect on image captures. Generally, the pixels value of an image is proportional to the illumination of point in the scene and the reflectance of the object. Indeed, the captured image is the results of illumination and reflectance of the object. Hence, impairment of the image may be due to each of the illumination or reflectance component. In this paper, it is shown that various types of impairments have different effects on the illumination and reflectance of image components. Studies showed that effects of image impairment on one of its components are more than on the other component depending on the type of impairment. Unlike conventional methods which do enhancement process on the original image for any type of impairment, in this paper it is to reduce the impairement effects from image components. Results of this research show that image enhancement based on the proposed method has better results compared to applying enhancement methods on original image
    Keywords: Image Enhancement, Image Component, Illumination, Reflectance
  • A. Hassanzadeh, Y. Zou, R. G. Lindquist Pages 1275-1280
    In this paper excitation characteristics of the Liquid Crystal (LC) capacitive chemical and biological sensor are examined and the optimum frequency and voltage range for the sensor interface are introduced. Interdigitated capacitor has been used for the sensor capacitance measurement and two different molecular orientations, homeotropic and homogenous, have been considered. The LC sensor capacitance has been measured for different frequencies from 20Hz to 2MHz and voltages from 0.5V to 20V. In both cases, the effects of excitation on the capacitance value and the accuracy of the measurement are investigated. Simulation and experimental results support the proposed range of measurement
    Keywords: Liquid Crystal Capacitive Sensor, Liquid Crystal Excitation, Interdigitated Capacitor
  • R. Ahilapriyadharshini, S. Arivazhagan Pages 1281-1288
    The proposed method is to recognize objects based on application of Local Steering Kernels (LSK) as Descriptors to the image patches. In order to represent the local properties of the images, patch is to be extracted where the variations occur in an image. To find the interest point, Wavelet based Salient Point detector is used. Then, Local Steering Kernel is applied to the resultant pixels in order to obtain the most promising features. The features extracted will be over complete; so, in order to reduce dimensionality, Principal Component Analysis (PCA) is applied. Further, the sparse histogram is taken over the PCA output. The classifier used here is Support Vector Machine (SVM) Classifier. Bench mark database used is UIUC car database and the results obtained are satisfactory. The results obtained using LSK kernel is compared by varying parameters such as patch size, number of salient points/patches, smoothing parameter and scaling parameter
    Keywords: Object Recognition, Salient Point Detector, Patch Extraction, Local Steering Kernel, Principal Component Analysis
  • M. Rezaei Darestani, A. A. Nikkhah, A. Khaki Sedigh Pages 1289-1298
    An integrated robust optimal control is presented to enhance the closed loop performance in the presence of disturbance and uncertainties, to ensure smooth tracking and elimination of high frequency disturbances especially in accurate systems with minimum power consumption. Simulation result of the proposed controller based on the combination of ℋ2 and ℋ∞ controllers is used to show the effectiveness of the proposed methodology. A 3 axis gyro-stabilized MIMO platform is considered and the results of the NLPID and a single ℋ∞ controller are compared with the proposed ℋ∞/ℋ2 controller
    Keywords: 3 Axis GSP, Predictive Control, ℋ2, ℋ∞ Control
  • R. Gholipour, A. Khosravi, H. Mojallali Pages 1299-1306
    The nonlinear behavior analysis and chaos control for Duffing-Holmes chaotic system is discussed in this paper. In order to suppress the irregular chaotic motion, an optimal back-stepping controller is designed. The back-stepping method consists of parameters with positive values. The improper selection of the parameters leads to inappropriate responses or even may lead to instability of the system. In this paper, the Unified particle swarm optimization (UPSO) algorithm is utilized to determine the convenient and optimal values of the parameters. The minimized objective function viaUPSO algorithm is a weighted sum of the Integral of Time multiplied Absolute Error (ITAE) and squared control signal. Fast control of chaos in a very short time and having more limited control signal for this purpose, are the great advantages of the proposed controller. Numerical simulationsshow the high performance of this method for chaos elimination in Duffing-Holmes system
    Keywords: Duffing, holmes System, Control of Chaos, Back, stepping Controller, UPSO Algorithm
  • T. Taleshian, A. Ranjbar, R. Ghaderi Pages 1307-1322
    In this paper, an intelligent-gradient based algorithm is proposed to solve time optimal bang-bang control problem. The proposed algorithm is a combination of an intelligent algorithm called improved particle swarm optimization algorithm (IPSO) in the first stage of optimization process together with a gradient-based algorithm called successive quadratic programming method (SQP) in the second stage. The proposed algorithm is called MIPSO-SQP algorithm which in essence is a modification of the previous IPSO-SQP algorithm (PIPSO-SQP). New steps in optimization process of the proposed MIPSO-SQP algorithm causes the algorithm to reach to global optimal solution regardless of any guess of the initial control input and/or the number of switching. Validity of results is verified through adding some arcs to present arcs. The proposed algorithm is successfully applied in time optimal bang-bang control of the Van Der Pol equations, Rayleigh system and F8 aircraft model. A comparison study is also performed to assess the performance of MIPSO-SQP with respect to Switching Time Optimal method (TOS), mathematical programming method and PIPSO-SQP algorithm. It is shown that MIPSO-SQP algorithm is more effective than these algorithms due to ability to find global optimum solution in less iteration and in a more systematic way
    Keywords: MIPSO, SQP Algorithm, Time Optimal Bang, Bang Control, Nonlinear Systems, Intelligent algorithm, Gradients, Based Algorithm
  • M. Taybi, B. A. Ganji Pages 1323-1330
    In this paper the effect of corrugations on mechanical sensitivity of diaphragm for MEMS capacitive microphone is investigated. Analytical analyses have been carried out to derive mathematic expression for mechanical sensitivity and displacement of corrugated diaphragm with residual stress. It is shown that the mechanical sensitivity and displacement of diaphragm can be modeled using thin plate theory. The mechanical stress of corrugated diaphragm is calculated using mathematical model and its relationship with residual stress is expressed. The analytical results show that the mechanical sensitivity of diaphragm can be increased using corrugations, because of reducing the effect of residual stress in corrugated diaphragm
    Keywords: Corrugated Diaphragm, Residual Stress, Mechanical Sensitivity, Diaphragm Displacement
  • B. A. Ganji, M. Shams Nateri Pages 1331-1336
    In this paper, for the first time, the modeling of capacitance and sensitivity for MEMS capacitive pressure sensor with clamped square diaphragm is presented. In capacitive sensor the sensitivity is proportional to deflection and capacitance changes with pressure. Therefore, first the diaphragm displacement, capacitance and sensitivity of sensor with square diaphragm have been modeled and then simulated using finite element method (FEM). It can be seen that the analytical results agree with simulation. The results also show that the high sensitivity can be achieved by decreasing the diaphragm thickness and increasing its size.
    Keywords: MEMS, Modeling, Displacement, Capacitance, Sensitivity
  • B. A. Ganji, A. Razeghi Pages 1337-1346
    This paper presents a new design of microwave microelectromechanical systems (MEMS) phase shifter for dual band wireless local area network (WLAN) applications. A bit is designed which produce a constant phase shift of 11.25° by switching between two lines that consist of 12 and 6 unitcells in each frequency band. A unitcell is constructed by gold membrane suspended over the coplanar waveguide (CPW) that can be moved vertically by electrostatic actuation. It can also ultimately be used for changing the operating frequency band. Two states of unitcell are used to switch between two frequency bands of 2.4 GHz and 5.2 GHz (IEEE 802.11 standard employed in dual band WLAN systems). First, a closed form equation of simplified model of the structure is obtained. Then, using this equation and advanced design system (ADS) simulator, the dual band phase shifter is designed. The validation of modeling and equations are demonstrated using the High Frequency Structure Simulator (HFSS). At the frequency of 2.4 GHz, maximum return and insertion losses are - 16.96 and -0.12 dB, respectively that exhibit a phase shift efficiency of 93.75 °/dB (60.22 °/cm). At the frequency of 5.2 GHz, maximum return and insertion loss are -16.86 and -0.15 dB, respectively exhibiting a phase shift efficiency of 75 °/dB (60.22 °/cm). The new proposed design is only to achieve a dual band phase shifter using MEMS technology which has low loss and weight with high linearity respect to the other technologies
    Keywords: MEMS, Dual Band, Phase Shifter, Coplanar Waveguide, Return, Insertion Losses
  • M. Ashourian, N. Daneshmandpour, O. Sharifi Tehrani, P. Moallem Pages 1347-1356
    License plate recognition (LPR) using morphology has the advantage of higher resistance to changes of brightness, high speed processing, and low complexity. However, these approaches are sensitive to the distance of the plate from the camera and imaging angle. Various assumptions reported in other works might be unrealistic, and cause major problems in practical experiences. In this paper we considered morphological approaches and improved them using adaptive techniques in order to provide more compatibility with practical applications. We examined the developed system on several car plate image databases with different conditions such as different camera distance, and different car views. The average achieved rate of success was 89.95% for all car plate location recognition, which is more than 6.0% improvement in comparison to previous morphological methods. We further developed and implemented an FPGA realization of the pre-processing stage of the system which is the main computation load of our LPR system
    Keywords: License Plate Recognition, Car Plate Location Recognition, Real Time Implementation, Adapted Morphology
  • S. M. Rakhtala, A. Ranjbar, R. Ghaderi Pages 1357-1368
    This paper presents a systematic approach to design a Lyapunov based super twisting differentiator. The differentiator will be shown convergent in a finite time whilst the relevant time is accurately estimated. This differentiator is the main part to establish the sliding surface in higher order sliding mode. The differentiator is used in the prescribed control structure to regulate pressures of hydrogen and oxygen of a nonlinear Polymer Electrolyte Membrane Fuel Cells (PEMFCs) to prolong the stack life. The aim of the control strategy is to minimize and keep the deviation between the pressures of hydrogen and oxygen. The deviation forms a sliding surface, where its appropriate differentiation is required in the control law. It is the reason for reconstructing finite time derivatives in a closed-loop control. Finally, simulation result and a comparative study verify the performance of the proposed differentiator and the control structure to provide convergent estimator in finite time
    Keywords: Finite Time Convergent, Nonlinear Modeling, Twisting Algorithm, Convergent Differentiator, Pressure Regulation
  • M. Nandhini Gayathri, T. Ganimozhi Page 1377
    This paper proposes a single-phase five-level inverter with a modified pulse width-modulated (PWM) control scheme. The modified pulse width-modulation technique is developed to reduce switching losses. Also, the proposed multilevel inverter can reduce the requirement of power switches compared to a conventional cascaded multilevel inverter. The modes of operation, control signals, and operating principle of the proposed inverter are analyzed. The inverter is capable of producing five levels of output-voltage (V s, Vs/2, 0, − V s, − V s/2) from the dc supply voltage. In particular, aspects of total harmonic distortion (THD) for the proposed multilevel converters are discussed. The hybrid cascaded H-Bridge inverter with very low switching losses is ideal for such operations. The behaviour of the inverter has been analyzed with the simulation and experimental results. In this paper a new five level inverter with reduced number of switches is proposed and MATLAB/SIMULINK results are presented
    Keywords: Hybrid Cascaded, THD, Modified PWM
  • H. Bagheri Tolabi, M. H. Moradi, F. Bagheri Tolabi Pages 1385-1392
    Solar radiation estimation is integral part for various solar energy systems which requires precise and expensive devices to gage the solar radiation for a particular region. However, researches have proposed different techniques to estimate the solar radiation that hinder using such devices so far. Nonlinear nature and excessive dependence on the meteorological parameters of these methods forced researchers to look for quick and efficient techniques to solve related issues and find solar radiation for a particular region. In this paper, a new method based on the Angstrom model is introduced which estimates the monthly average daily global solar radiation on a horizontal surface by Bees Algorithm as a heuristic and population-based search technique implemented in MATLAB software. The experimental coefficients for Angstrom model are calculated for six different climate regions of Iran using proposed program written in the software. The obtained results proved the efficiency and predominance of the new method to find a more accurate level of solar radiation
    Keywords: Bees Algorithm, Global Solar Radiation, Experimental Coefficients, Statistical Regression Techniques, Intelligent Techniques
  • A. Udawat, P. C. Sharma, S. Katiyal Pages 1393-1400
    In the present paper convergence characteristics of Sample Matrix Inversion (SMI) and Least Mean quare (LMS) adaptive beam-forming algorithms (ABFA) are compared for a Smart Antenna System (SAS) in a multipath environment. SAS are employed at base stations for radiating narrow beams at the desired mobile users. The ABFA are incorporated in the digital signal processors for adjusting the weights to adjust the beam on the desired user and generate null in the direction of interferer. SMI and LMS algorithms are used with SAS for improving the performance of wireless communication system by optimizing the radiation pattern according to the signal environment. This can enhance the coverage and capacity of the system in multipath environment by reducing the interference and noise. The data rate can be enhanced by mitigating fading due to cancellation of multipath components. In this paper, optimization capabilities of SMI and LMS are considered by changing the parameters. The results reveal improvement in gain, speed of convergence and reduction in side-lobe level.
    Keywords: Smart Antenna Systems, SMI, LMS, Angle of Arrival (AOA), Multipath, Array Factor