Digital signal processors (DSPs) are very important in various engineering disciplines. Fast multiplication is very ­important in DSPs for convolution, Fourier transforms etc. A fast method for multiplication based on ancient Indian Vedic mathematics is proposed in this paper. Among the various methods of multiplications in Vedic mathematics, Urdhva tiryakbhyam is discussed in detail. Urdhva tiryakbhyam is a general multiplication formula applicable to all cases of multiplication. This algorithm is applied to digital arithmetic and multiplier architecture is formulated. This is a highly modular design in which smaller blocks can be used to build higher blocks. The coding is done in VHDL (very high speed integrated circuits hardware description language) and synthesis is done using Xilinx ISE series. The combinational delay obtained after synthesis is compared with the performance of the modified Booth Wallace multiplier which is a fast multiplier. This Vedic multiplier can bring about great improvement in DSP performance.

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In this paper, the blind code extraction of Direct Sequence Code - Division Multiple Access signals is considered based on independent component analysis (ICA), some propositions are defined in order to estimate the number of active users, to distinguish between correct and incorrect extracted codes, and also to determine the quality of detection along with the ICA-based blind detection procedure. These propositions are used to improve the performance of the ICA blind detection-based method. Principal component analysis and gaussian mixture model are employed as analyzing tools in proposed criteria. Experimental results show that the defined criteria are verified.

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In medical imaging, image denoising has become a very essential exercise all through the diagnosis. Compromise between the preservation of useful diagnostic information and noise suppression must be respected in medical ­images. One of the ultimate goals of an imaging modality is to provide the clinician with the best possible information needed to make an accurate diagnosis. Ultrasound images suffer from an intrinsic artifact called speckle. Speckle degrades spatial and contrast resolution and obscures the underlying anatomy. Thus, it seems sensible to reduce speckle ­artifacts before performing image analysis, provided the image that might distinguish one tissue from another is preserved. The main goal of this thesis was the development of novel methods for suppression of speckle in medical ultrasound images in the wavelet domain. We have adopted weighted variance for estimating the threshold and multiscale product scheme for thresholding the coefficients. To employ the wavelet interscale dependencies, the adjacent wavelet subbands are multiplied. Multiplying the adjacent wavelet scales would sharpen the important structures while reducing noise. In the multiscale products, edges can be efficiently discriminated from noise. Then, an adaptive threshold was calculated and imposed on the products, instead of on the wavelet coefficients, to identify important features. Fundamentally speckle noise is a signal-dependent one, and so weighted variance of each background pixel was taken into account while calculating threshold. Experiments show that the proposed scheme better suppresses noise and preserves edges than other wavelet-denoising methods. Experiments with synthetic and real ultrasound imagery show that the proposed method improves the signal-to-noise ratio and preserves edge clarity.

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This paper deals with various multipulse AC-DC converters for improving the power quality in vector-controlled induction motor drives (VCIMDs) at the point of common coupling. These multipulse AC-DC converters are realized using a reduced rating autotransformer. Moreover, DC ripple reinjection is used to double the rectification pulses resulting in an effective harmonic mitigation. The proposed AC-DC converter is able to eliminate up to 21st harmonics in the supply current. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC-DC converter. A set of power quality indices on input AC mains and on the DC bus for a VCIMD fed from different AC-DC converters is also given to compare their performance.

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Use of conventional two-level pulse width modulation (PWM) inverters provide less distorted current and voltage but at the cost of higher switching losses due to high switching frequencies. Multilevel inverters are emerging as a viable alternative for high power, medium voltage applications. This paper compares total harmonic distortion and switching losses in conventional two-level inverters with multilevel inverters (three-level and five-level) at different switching frequencies. An optimized switching frequency has been obtained for a lower level of total harmonic distortion and switching losses. Diode-clamped, three-phase topology is considered for study. A sinusoidal PWM technique is used to control the switches of the inverter. Simulation study confirms the reduction in harmonic distortion and switching losses as the number of the levels increases.

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Switched Mode Power Supplies (SMPS) of medium power ratings are extensively used in heating, welding and telecommunication power supply applications. Invariably, they use a 3-phase ac-dc converter at the front end. In this paper, different autoconnected transformer-based 9-phase ac-dc converter configurations are designed, modeled and simulated to feed such medium capacity SMPS for improving the power quality indices at the point of common coupling (PCC). The autoconnected transformer is designed suitable for producing 9-phase voltages of same magnitude and having equal phase shift. The proposed 9-phase ac-dc converters are found capable of suppressing up to 17th harmonic in the supply current along with the power factor improvement close to unity at varying loads. A set of power quality indices on input ac mains and magnetic ratings for various autoconnected transformer configurations for this SMPS are also presented so that the best converter configuration can be chosen according to the requirements for a particular application.

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Distribution Static Compensator is an important device in correcting power factor, maintaining constant distribution voltage, and mitigating harmonics in a distribution network. This paper focuses on the comparative study of the control techniques for voltage source converter based Distribution Static Compensator, broadly classified as voltage controlled and current controlled. Under the former, phase shift control is compared with the latter, considering indirect decoupled current control and regulation of AC bus and Dc link voltage with hysteresis current control. The first two schemes have been successfully implemented for Static Compensator control at the transmission level for reactive power compensation and voltage support, and are recently being incorporated to control a Distribution Static Compensator employed at the distribution end. The following indices are considered for comparison - measurement and signal conditioning requirement, performance with varying linear/nonlinear load, total harmonic distortion, DC link voltage variation and switching frequency. The paper briefly describes the salient features of each strategy, with their merits and demerits. A dynamic simulation model of the Distribution Static Compensator has been developed for various control strategies, in Matlab/SimPower System environment.

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The effect of a lossy overlay on the read-range of UHF RFID tags is studied. The design of the tag antenna is optimized for long read-ranges and then the effects of a lossy overlay (cover) on its properties are studied. The tags are simulated with and without the lossy overlay material. The input impedance of tag antenna, power transmission coefficient and read-range are calculated and compared for the two cases of with and without overlay. Further, optimization of tag with lossy dielectric overlay is carried out. It is observed that even with the overlay of a lossy dielectric, read-range up to 9 m can be obtained by properly matching the antenna with the RFID IC.

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This paper presents modeling, simulation and development of high frequency isolation based single-phase buck-boost AC-DC Cuk converter, which consists of only one switch, resulting in simplicity in design and manufacturing, and reduction in input current total harmonic distortion (THD). Design and analysis are carried out for a 13.5 V output voltage and 20.25 W output power. To validate the design of the converter at the primary stage, the simulation is performed in discontinuous conduction mode (DCM) and continuous conduction mode (CCM) of operation, using PSJM 6.0 platform, which shows high-level steady state and dynamic performance. A laboratory prototype of the proposed single switch Cuk buck-boost converter in DCM operation is developed and test results are presented to validate the proposed design and developed model of the system.

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Underwater scenario with all its complexities has been always very challenging for sonar signal processing. The ­reverberation and the fast-fading nature of the channel make it necessary to use chirp waveforms for sonar transmissions. The conventional techniques based on Fourier transforms often fail to fully address the issues like Doppler estimation with chirp waveforms and low signal-to-noise ratio detection due to the vagaries of the medium. Alternately, the fractional Fourier transform (henceforth shortened as FrFT) can be used in sonar signal processing for improved chirp-detection performance. However, this useful signal-processing tool is largely unknown to the sonar signal processing community. This paper demonstrates the application of FrFT in active and intercept sonar signal processing. The motivation to adopt the proposed method is the ability of FrFT to process chirp signals better than the conventional Fourier transform. FrFT is a parameterized transform with parameter a, related to the chirp rate. Many active sonar systems choose to transmit chirp signals for better detection in the presence of reverberation. FrFT if used instead of FFT in the correlation receiver has great potential as it takes advantage of the knowledge of transmitted waveform and can be therefore implemented for the optimum order. In the simulations, performance of matched filtering with FrFT has been compared with performance using conventional FFT. In the case of intercept sonar, FrFT can be used to estimate the parameters of chirps from a multi-component signal. This paper presents a novel parameter-estimation procedure by which chirp parameters are calculated from the two primary estimates, namely, optimum order and FrFT peak position. Simulation results clearly demonstrate the potential advantages of the proposed methods.

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In this paper, we report design, development and fabrication of high-performance Ka-band micromachined patch antennas using monolithic microwave integrated circuit (MMIC)-compatible process technology. The main emphasis of this paper is to use radio frequency (RF) sputtering as the potential metal-dielectric film deposition process for rapid prototyping of many antenna structures in the absence of access to a well-established MEMS foundry. The fabricated antennas exhibited 4%-5% of impedance bandwidth, which is much wider than the one fabricated on bulk high-index substrates.

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An Intel 8751 microcontroller-based system was developed to monitor and control the temperature of an oven. The IN4148 signal diode was used as the temperature sensor and the on-off control algorithm was utilized with the system switching off the heating process whenever it attains the preset value. The system provides a digital readout of the system temperature and a status/blinker indicator showing whether heating is in progress or terminated. The control programs were loaded onto the memory of the microcontroller and the enable the selection of the different temperature values. The system improves accuracy by eliminating human participation and saves operator time. The system is easy to operate, maintain, and upgrade.

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This paper deals with a voltage and frequency control of an isolated asynchronous generator feeding 3-phase 4-wire loads in constant power applications where terminal voltage, excitation capacitor, speed and generated power of the generator remain constant under all operating conditions. The proposed controller is functioning as an improved electronic load controller (IELC) to regulate the frequency and as a source of reactive power to regulate the terminal voltage. Three single-phase voltage source converters (VSCs) are connected to each phase of the generator through three single-phase transformers and there is an auxiliary load with a chopper at the self-regulated DC bus of the IELC. These VSCs along with transformers provide their function as a voltage regulator, a harmonic eliminator, a load balancer and a neutral current compensator whereas the chopper and the auxiliary load at the DC bus are used to regulate the frequency. The complete system is modelled and simulated in MATLAB along with Simulink and Power system Block set toolboxes. The simulated results are presented to demonstrate the capability of an isolated generating system driven by uncontrolled pico hydro turbine and feeding 3-phase 4-wire linear/non-linear balanced/unbalanced loads.

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In this paper, a non-isolated inductor-capacitor-capacitor (LCC) topology based DC-DC converter for automotive application is practically implemented. The resonant tank with one inductor and two capacitors provides soft switching of the inverter switches and a voltage gain of 2. All possible LCC topologies are listed and categorized based on the order of their voltage gain expression. Based on the source/sink requirement for automotive application, some topologies are found to be realizable. For all these realizable topologies, voltage gain expressions are obtained and plotted against normalized frequency. From the voltage gain plots, one candidate topology is chosen and analyzed further. Expressions for current gain, stress across resonant tank elements, circulating reactive power and stored energy in the tank are obtained. The optimum value of Q which results in smallest possible resonant tank is determined and is found to be 0.545. The resonant tank is designed and implemented based on the optimum value of Q. Experimental results show that soft switching is achieved for a wide load range and is suitable for automotive application.

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This paper proposes a non-isolated 36-pulse controlled AC-DC converter for medium power rating drives. It involves pulse multiplication in a 12-pulse AC-DC converter. The approach employs a polygon autotransformer arrangement, which results in a near equal leakage reactance in series with each thyristor bridge. The volt-ampere rating of the autotransformer is observed to be small and the converter meets IEEE-519 standard power-quality requirements over a wide range of firing angle.

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In this paper, the authors present a new planar metamaterial loaded electrically small microstrip patch antenna. The rectangular microstrip patch antenna is loaded by metamaterial using planar square spilt ring resonators (SRRs). The unloaded rectangular microstrip patch antenna resonates at 23 GHz, whereas after loading it by metamaterial, the same antenna resonates at 9.51 GHz. In loaded condition, the resonant frequency of rectangular microstrip patch antenna reduces due to magnetic coupling. The dimensions of the antenna structure are 0.161λ × 0.192λ. Using the Chu limit, the size of the antenna comes to ka = 0.775, thus, satisfies the condition of an electrically small antenna (ka < 1). The antenna exhibits an impedance bandwidth of 512 MHz at a resonant frequency of 9.51 GHz. The calculated radiation Q_rad is 18.86 which is larger than Q_chu minimum, that is Q_chu = 3.43. The gain and directivity of this antenna structure are 3.2 dBi and 7.8 dBi, respectively. The proposed antenna structure is simulated on a dielectric substrate with coaxial fed without incorporating any additional matching network.

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Estimation of Dilution of Precision (DOP) plays an important role in aviation, terrestrial and marine navigation applications. In this paper results due to four techniques to estimate DOP namely, Kihara's method, 'all-in-view' SVs, 'best-5' SVs and 'best-4' SVs are investigated. Experiments are performed using Novatel (DL-4plus) GPS receiver and the collected data is used for the analysis. Bancroft algorithm is used to find preliminary position of the receiver. Using this position of the receiver and satellite coordinates, DOP is estimated. Comparative analysis of the specified techniques is performed. For most of the time, DOP values due to 'all-in-view' SVs are found as the best.

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This paper deals with the real time implementation of 11-level cascade multilevel inverter-based STATCOM using personal computer (PC) and ADD-ON cards for power system voltage control at the point of common coupling. Complete hardware and software development procedures have been explained in depth for direct as well as indirect control schemes. Experimental results are presented and it is shown that voltage control is achieved using cascade multilevel inverter based STATCOM, thus verifying the very basic purpose of STATCOM. Real time implementation using PC-based control technique has certain merits over digital signal processor based implementation, and some of these merits are high processing speed and low cost of implementation; therefore, PC-based implementation can be used in industry as well as for utility applications.

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The periodic nonlinearity in nano-metrology systems based on heterodyne interferometers is the most important limitation to the accuracy of displacement measurement. It is mainly produced due to the polarization-mixing and frequency-mixing. In this paper, a new approach based on an ensemble of neural networks for modeling and compensation of nonlinearity in a high-resolution laser heterodyne interferometer is presented. We model the periodic nonlinearity arising from elliptical polarization and non-orthogonality of the laser polarized light based on the neural network approaches, including the multi-layer perceptrons and radial basis function as single neural networks and stacked generalization method as ensemble of neural networks. It is also shown that by using the stacked generalization method, the primary periodic nonlinearity of 1.3 nm is significantly compensated by a factor of 168.

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This paper deals with three different configurations of Distribution Static Synchronous Compensator (DSTATCOM) for distribution system. Detailed analysis, modeling, design and control are discussed for each configuration of DSTATCOM. MATLAB based models are developed for improving power factor/voltage regulation and neutral current compensation. Results show a marked reduction in total harmonic distortion (THD) of supply current levels when applied to nonlinear loads. Dynamics of systems are reported with sudden load addition or removal and performance of system is demonstrated in detail.

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In this paper, an implementation of a space vector modulation (SVM) based hysteresis current controller (HCC) for the control of a three-phase high power factor rectifier is proposed. The SVM-based HCC scheme is designed, simulated and implemented. The technique combines the best features of the SVM and HCC techniques. The controller determines a set of state space vectors from a region detector and then applies a space vector selected according to HCC. A set of space vectors in a region, including the zero space vector for a reduced number of switchings, is determined from the output signals of three comparators with a hysteresis band a little larger than that of the main HCC. A simple experimental implementation is proposed and the simulation and experimental results of the SVM-based HCC are discussed in the paper.

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Machines never break down by chance. Their operating condition gradually deteriorates and this gradual quantitative deterioration transforms into a failure, manifesting a qualitative change. When a fault takes place, some of the machine parameters are subjected to change. The change in the machine parameter depends on the degree of faults and the interaction with other parameters. In most cases, more than one parameter is subjected to change under abnormal conditions. If these machine parameters can be measured, they give information relating to a developing fault and then maintenance can be planned for the next available shutdown. Therefore, condition monitoring requires measurement to be taken from the machine on a continuous basis and is used to indicate the current working condition of that machine. There are a number of parameters that can be considered for monitoring the machine. For induction machines, monitoring parameters are terminal voltages, line currents, stack temperature of stator, rotor speed, torque, stator frame vibration, bearing vibrations, etc. ^{[1],[2],[3],[4]} This paper discusses the results of the laboratory investigations carried out on 10-hp cage induction motors to identify the machine health by monitoring. A data acquisition system, capable of recording vibration, line currents and line voltages, is designed and fabricated. The signals are sampled at a suitable sampling frequency using an add-on card and are saved in a computer for future use. The vibration signals are measured at a load end bearing of the test motor. The recorded vibration signals are then pre-processed both in time and frequency domain to extract the important features that contain the maximum fault information. The selected features are analysed for their class separation capability using the Fisher criterion. These features are then used as an input to the fault classifier. The fault classifier used in this study is the multi-layered perception trained with a back propagation algorithm. Two networks are trained independently, one with time domain parameters, module-TD, and the other with frequency domain parameters, module-FD. It is found that module-TD gives its best performance for incipient fault detection (100%); however, for medium degree fault, it gives an 85% efficiency. The frequency parameter-based module gives a better performance for both the cases (98 and 95% respectively). However, a combination of the two can be used to enhance the decision ability of the system.

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This paper proposes a new approach to enhance peak signal to noise ratio of highly corrupted image affected by impulse noise. The proposed technique is implemented using an adaptive median filter and the bacterial foraging optimization (BFO) technique. The adaptive median filter is used to identify pixels affected by noise and replace them with median value to keep the information uncorrupted. The BFO technique minimizes errors between adaptive median filter output image and noisy image to maintain an error percentage of 0.0001. It has been observed that results of the proposed method are superior to conventional methods in terms of perceptual image quality as well as clarity and smoothness in edge regions of the resultant image. This technique can remove the salt-and-pepper noise of highly corrupted images with a noise as high as 90%.

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The paper presents an improved variant of bacterial foraging optimization (BFO) named as Synchronous Bacterial Foraging Optimization (SBFO). The proposed SBFO is used to optimize multimodal and high dimensional functions. As all the bacteria update their information simultaneously, it has been named synchronous. A mutation operator proposed in this paper performs the global search. In SBFO, all bacteria process information independently in the same generation; hence parallel computers can be used to evaluate fitness values. The performance of SBFO is validated on a set of seven benchmark functions i.e. Sphere, Rosenbrock, Rastrigin, Griewank, Ackley, Schaffer's, Shekel's Foxholes. The results are compared with other published methods such as classical BFO, hybrid BFO (BSO), swarm-based algorithms, differential evaluation and Ashaker. The simulation results on benchmark functions show that the proposed optimization is capable of producing good quality global optima as compared to the above mentioned optimization techniques. The proposed method is a new variant of BFO and suitable for optimization of multimodal and high dimensional functions.

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This paper presents the investigations of various broad banding and minimization techniques for square patch antenna. For bandwidth enhancement, square patch antenna with U shaped slot and L probe feed have been considered. Using these techniques, bandwidth in the range of 30 - 40% has been achieved. In addition to this, techniques to minimize patch antenna's surface area have also been analyzed. The shorting pin and shorting wall methods have been used for minimization. Simulation has been carried out using IE3D software.

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