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Super resolution (SR) is one of the techniques to enhance image resolution in terms of the number of pixels and noise reduction. In SR techniques, a sequence of low resolution (LR) images captured by moderate camera is used to generate a high resolution (HR) image. In this thesis a new Iterative Back Projection (IBP) based SR technique is proposed. In the proposed techniques, IBP technique is improved by using interpolation. This SR technique is achieved by adding an up-sampling and down sampling in each iteration. First of all, four observed LR images are generated by an observation LR model. One of these LR images is considered as a reference image, then interpolation techniques are used to increase the size of the reference image to the size of the ground truth image. This image is considered as an initial guess image. Then the size of initial image is increased and decreased respectively by using interpolation techniques. The interpolated image is decimated to four LR images. The LR images are registered to generate an HR image, then the HR image is sent back to the first step. This process is repeated iteratively until an error criterion is met. The proposed technique is called Iterative Interpolation and Back Projection (IIBP), since an interpolation (up-sampling followed by down-sampling) module is embedded in each iteration. The embedded interpolation module speeds up the convergence of the standard IBP and generates faster results than the standard IBP. The proposed techniques are tested on various well-known benchmark images. The quantitative Peak Signal-to-Noise Ratio (PSNR) results as well as the visual results show the superiority of the proposed techniques over the standard IBP whenever limited numbers of iterations are allowed. As the number of iterations approach to infinity, generally standard IBP gives better results. Keywords: Super Resolution, Iterative Back Projection, Image Registration
Two matching techniques namely linearly tapered and multistep transition were used to design two dimensional radiators between parallel plate regions and 50 microstrip feed line. Transitions for different aperture widths were designed at 2.45GHz, by using a full wave simulation software. As these radiators are not point radiators, they may cause phase errors. In this study, a simple method is suggested to estimate the phase center of the radiating apertures and reduce the phase errors. The suggested method is based on the phase equally in the broadside direction and at another constant angle. The study has been carried out by using a full wave simulation software. The results show that there is almost no phase error over the range of angles of interest for the estimated phase center at the design frequency. The position of the phase does not vary with the distance from the radiator, which means that there are no phase errors as the distance from the radiator varies. Although there is some phase errors as the frequency is decreased or increased, these errors are not significant over a wide band of frequencies. For the multistep transition it is observed that the position of the phase center is closer to the center of the radiator aperture, for the wide apertures. Keyword: Phase center, parallel plate, two dimensional radiation, far field region
Several modern-day antenna applications require the radiated fields to be focused at a predetermined point away from the antenna to perform different tasks, such as sensing, testing, charging, diagnosing, and treatment of different medical conditions. In this thesis, a thorough study has been made to investigate the characteristics of near-field focusing. In many applications, along with focusing the radiated fields at a focal point, it is also required to move that focused beam to scan a specific region i.e., usually carried out either electronically or physically by changing the position of the antenna array. The thesis proposes a robust mechanism to move the focused beam at single and dual focal points to improve the scanning properties of the antenna array. The proposed mechanism does not depend upon any external phase shifter circuit or changing the position of the array for focusing and scanning the focused beam. The movement of the focused beam is achieved as a result of introducing extra transmission lines to the scanning axis of the array. Antenna designs for single-focal and dual-focal points are analyzed using MATLAB and CST simulation software. The simulation results show that the proposed designs work efficiently as the movement of the beam is controlled by the change in frequency. Furthermore, in the case of dual focal point near field focused antenna array, there is a significant increase in the scanning distance as compared to the single focal point. The proposed mechanism results in an increment in scanning distance of around 53%. The proposed designs can be used in applications such as RFID, Non-destructive industrial inspection and testing, and wireless power transfer, where the focused beam is to be directed at a point in the near-field and the scanning of the focused beam is required as well. Keywords: microstrip patch antenna array, near-field focusing, parasitic patch, hyperthermia, beam scanning.
Currently, one of the most significant health issues affecting women is breast cancer. Breast cancer, which has the highest mortality and morbidity rates among diseases that affect women, poses a severe threat to their lives and health. It is crucial to diagnose breast cancer early. Recently, the technological and theoretical developments in innovative techniques such as machine learning made it possible to achieve early diagnoses of breast cancer. Using Convolutional Neural Networks (CNNs) and Support Vector Machines (SVMs) for breast cancer detection, we developed a Computer-Aided Diagnosis (CAD) system to identify breast tumors from mammogram images. The proposed system is composed of four stages. Firstly, CNN is used to classify mammogram images. Secondly, CNN-based features are extracted and used with a standard classifier, which is SVM, to identify potential tumors. Thirdly, SVM is used to distinguish between different types of tumors based on the extracted features. Finally, a data fusion method is employed to combine the results obtained from the first, second, and third methods to improve the overall performance of the system. The individual techniques, accuracy is increased, and it reaches around 99% by using fusion methods. Keywords: Breast Cancer, Convolutional Neural Network, Computer-Aided Diagnosis, Support Vector Machine, Fusion Methods
Robust adaptive beamforming has long been an attractive research topic over several decades due to wide applications in vast fields of signal processing such as, radar, sonar, wireless communications, medical imaging, microphone array speech processing and other areas. Adaptive beamforming improves the reception of desired signals in the presence of interference signals automatically by sensing the presence of interferences and suppressing them while simultaneously enhancing desired signal reception without prior knowledge of the signal and interference environment. However, under certain circumstances, adaptive beamformers suffer performance degradation due to several reasons which include small sample size, the presence of the desired signal in the training data, the presence of nonstationary interference, or imprecise knowledge of the steering vector of the desired signal. Moreover, conventional approaches are very sensitive to these types of mismatches, do not provide sufficient robustness and may suffer from severe performance degradation in such situations. In this thesis, we propose three different types of novel adaptive beamforming techniques to resolve the effects caused by some of the aforementioned difficulties. A general goal in adaptive beamforming is to adaptively steer a beam towards a desired signal, while placing nulls at interference directions. The well-known minimum variance distortionless response (MVDR) adaptive beamformer is designed to linearly combine the outputs of the sensors in order to minimize the array output power, while maintaining a fixed response towards the desired signal. However, it is well known that the MVDR beamformer is quiet sensitive to the mismatch between the actual steering vector and the assumed one, which could be caused by any array imperfection. In the first approach, a robust adaptive beamforming technique based on a modification of the robust Capon beamforming approach is introduced which estimates the steering vector using eigenspace projection-based approximation. The steering vector is estimated as a reasonable approximation for the orthogonal projection of the presumed steering vector of the desired signal onto the signal-plus-interference subspace. In this approach, the optimal diagonal loading factor corresponds to the minimum of the estimated beamformer output power. Also, estimation of the desired signal’s direction-of-arrival is utilized to update the presumed steering vector. On the other hand, during the past decade, many approaches based on the processing of the sample covariance matrix have been proposed. However, since the desired signal component is usually included in this matrix, the beamformer is sensitive to slight mismatches. Although, some techniques have been proposed to remove the signal-of-interest (SOI) component from the signal covariance matrix using the reconstruction of the interference-plus-noise covariance (IPNC) matrix, these have a number of drawbacks. In the second approach, we introduce a low complexity procedure for IPNC matrix construction. The main motivation of this algorithm is to simplify the estimation of the IPNC matrix using its theoretical expression which is based on projection processing for covariance matrix construction and desired-signal steering vector estimation. In this accordance, the optimal minimum variance distortion-less response beamformer is closely achieved through approximating the interference-plus-noise covariance matrix by utilizing the eigenvalue decomposition of the received signal’s covariance matrix. Moreover, the direction-of-arrival (DOA) of the desired signal is estimated by maximizing the beamformer output power in a certain angular sector. In particular, the proposed beamformer utilizes the aforementioned DOA in order to estimate the desired-signal’s steering vector for general steering vector mismatches. In addition, adaptive beamforming methods are sensitive to underlying assumptions on the environment, sources, or sensor array violation, especially when interferences are moving fast. In recent years, research efforts have been devoted to the development of beamforming using covariance matrix taper (CMT) or additional constraints in the optimization programming for suppression of pre-defined angular ranges. This research presents an innovative beamforming approach in which the nonstationary interference source is estimated during the period in which snapshots are taken. Then, a new interference-plus-noise covariance matrix reconstruction is introduced which is derived from a simplified power spectral density function that can be used to shape the directional response of the beamformer. Finally, the beamformer is designed to impose nulls toward the regions of the moving interference based on the reconstructed covariance matrix. The essence of the proposed method is to express the inverse of the reconstructed covariance matrix in such a way that significantly reduces computational complexity. Theoretical analysis and simulation results indicate the superior performance of the introduced proposed approaches in the presence of mismatches relative to other some existing methods.
ABSTRACT: In dynamical system it is impossible to avoid dealing with uncertain conditions such as disturbances; that case is applicable on the UPS Inverter. There are many approaches to control inverters; here we are going to introduce a new approach of sliding mode control applied to UPS inverters. We reduce the sliding time of the state trajectory, by defining a function with respect to the error norm. This function gives the system a value of the sliding line at each instance, such that the performance is improved. The function is defined as the norm of both voltage error and its derivative multiplied by a factor. The norm value is saturated for small and large value of λ, which represents the slope of the sliding line. Another parameter (β) is also introduced, which is a gain multiplying the result of the saturated function. When the state is far from the origin, small value of λ is used in the reaching mode, while large value of λ is used when the state reaches the sliding line and start to “slide” on the sliding line. From the definition of the norm error, a function is derived which is used to minimize the reaching time. The results of simulation are compared to Three level hysteresis and rotating sliding mode approaches. The new approach shows a fast response with very small value of the voltage error. Keywords: uninterruptible power supply, inverters, sliding mode control, rotating sliding line. ……………………………………………………………………………………………………………………………………………………………………………………………………………………
This thesis aims to develop new control methods for the single-phase quasi-Z-source inverters (qZSIs). The key challenge lies in the design of suitable control method for the qZSI which is a nonlinear multi-input-multi-output (MIMO) system. Hence, from the control point of view, developing an integrated control technique is a challenging issue. Although the conventional control methods attain reasonable responses, suppression of double frequency ripple (DFR), robustness against parameter variations and simplification issues are still open issues. Thus, the proposed new control methods target to achieve these objectives. A novel approach which is created based on the model of the system while tuning the current of the system (MBCC) with DFR mitigation, virtual time constant and active damping to damp the resonances of the LCL filter is presented for a grid-tied qZSI as the first control method in this thesis. The second control method proposed in this thesis is a MIMO sliding mode control (SMC) which aims to control all variables of qZSI concurrently. This control approach not only synchronizes the control of all state variables at the same time, but also offers simplification in the implementation without using proportional-integral (PI) controllers in the dc-side, robustness to parameter variations, DFR mitigation when the sliding constant in the dc-side is selected appropriately and fixed switching frequency by introducing boundary layer technique. The boundary layer smooths the sliding functions and makes them appropriate for the PWMprocess. The applicability of the MIMO SMC method is also investigated for a single-phase high gain Z-source inverter which is called switched Z-source inverter (SZSI) in the literature. The effectiveness and validity of the proposed control methods are supported by simulation results in MATLAB/Simulink environment and the experimental results. The results show that the DFR mitigation approach can remove the DFR in the inductor current successfully and the MBCC method is also an efficient approach with fast dynamic response, zero steady state error and active damping of the resonance. Moreover, MIMO SMC can also achieve the goals with zero steady state error, robustness against parameter variation and fast dynamic response while attaining fixed switching frequency. Keywords: Active damping, double frequency ripple, quasi-Z-source inverter, LCL filter, proportional-resonant control, boundary layer, sliding mode control, switched Z-source inverter
Within the last decade, with the development of communication technologies and the increasing growth in the internet has become insecure, so it created different techniques to solve this problem. One of these techniques is the digital watermark, which provides the protection of property rights. In this thesis, we suggest new techniques of watermarking image aim to increase the degree of robustness of the watermark against various attacks and to increase the imperceptibility of the watermark image. Also these techniques aim to ensure the watermark image using Arnold transform where the watermark is available only to a legitimate user. The proposed approaches of watermarking image based on DWT, DCT and SVD have been applied on gray and color images in different color spaces like RGB, YIQ and YCbCr. Therefore, we have seven proposed algorithms namely: a gray image watermarking technique, an image watermarking technique in RGB color space (using a gray watermark image), an image watermarking technique in RGB color space (using a color watermark image), an image watermarking technique in YIG color space (using a gray watermark image), an image watermarking technique in YIQ color space (using a color watermark image), an image watermarking technique in YCbCr color space (using a gray watermark image) and an image watermarking technique in YCbCr color space (using a color watermark image). The difference between these algorithms is the type of watermark and the colorspace used (gray or color image: RGB, YIQ or YCbCr). To test the performance of proposed approaches, we calculated the PSNR and the SSIM. The best proposed approach which gives high robustness and imperceptibility of the watermark image against different attacks is an image watermarking technique in YIQ colour space (using a gray watermark image). And, the worst proposed approach which gives low robustness and low imperceptibility of the watermark image against different attacks is an image watermarking technique in YCbCr color space (using a color watermark image). In addition, our proposed approaches give high imperceptibility and high robustness of the watermark image when compared with other techniques [17][22][23]. Through the results, it has been verified superiority of our proposed approaches on many techniques. Our proposed approaches have high robustness of the watermark against various attacks with high quality for the watermarked image and security of the watermark image. Keywords: Watermarking Image, robustness, imperceptibility, PSNR, SSIM.
ABSTRACT: 3D models of environments and buildings are widely used in Geographical Information Systems (GIS), building information models, constructional management, environmental planning, city guides, path finding and Robotic applications, where the accuracy of data collection and resolution of the 3D model have been the main concern. 3D models of buildings and other objects can be constructed by following three main steps, namely, data acquisition, alignment and surface reconstruction. This project aims at introducing the process of forming a 3-D model from 3-D scan data and describing the data acquisition, alignment and surface reconstruction sequences in detail. Hardware and software design and implementation has been made for each stage of the 3D modelling process and a full grasp of the system is achieved. However, due to the complexity of the system, and also due to time limitation, it was not possible to achieve sufficient performance from the designed system. Instead, a commercial 3D laser scanner was used for the sake of completing the requirements of the 3D Modelling process with a reasonable performance. Current data acquisition systems have been reviewed and compared to discuss their advantages and drawbacks, as a result of which, 3D laser scanner has been chosen to be the most accurate and fast data acquisition system appropriate for scanning indoor and outdoor environments. Due to some limitations of the available 3D laser scanners, a commercial 1D-laser scanner has been converted into a 3D laser scanner, by designing and constructing a pan-tilt mechanism for the 3 axis control of the 1D laser scanner. The new 3D laser scanner is a simple and light in weight, which is easily adopted to a remote operating and monitoring Vehicle (ROMV) which has been designed in this project to add an indoor and outdoor mobility feature to the device. Although the new 3D Laser scanner operates properly, the accuracy and resolution of the scan results are not as expected yet. In order to complete the 3D modelling process with a reasonable accuracy and resolution, data acquisition is achieved by using the 3D laser scanner provided form the Stevens Institute of technology (CAD eye Scanner). This system is not only able to scan indoor and outdoor environments with acceptable resolution, but also it is able to collect RGB data corresponding to each scanned point in the scanned environment. For the Alignment or Registration of the acquired coordinate data obtained by the 3D Laser scanner, this research has used the semi- automatic method produced by an academic software tool called Mesh-lab. Point cloud model of the Techno park building was obtained by using professional software called Pointools. Surface reconstruction methods are investigated to obtain models with seamless and smooth surfaces from the point cloud model. It is realized that the existing methods fail to produce realistic surfaces under noisy data and a new method based on implicit surface reconstruction using isotropic basis functions has been developed to represent the sharp features more close to their real appearance. Some initial simple results of this method are presented in the thesis. A further work is needed to apply this method to reconstruct the surfaces of a complete 3D building model. Keywords: 3D Laser scanner, surface reconstruction, registration, radial basis functions, generalization..........
Multiple wireless interfaces in modern devices today have given great promise in enhancing multimedia service delivery over wireless networks. However, the IP coupled nature of the conventional TCP/IP protocol inhibits the simultaneous use of these interfaces. Multipath TCP (MPTCP), a protocol undergoing IETF standardization has been developed to simultaneously use multiple interfaces for delivery of services over the Internet. Unlike other earlier studies that use simulations, stationary scenario, and Advanced Video Codec-Dynamic Adaptive Streaming over HTTP (AVC-DASH) to study MPTCP, this thesis uses mobile scenario, real measurements, and Ultra High Definition, High Efficiency Video Codec (UHD HEVC-DASH) to evaluate the performance of MPTCP. The findings show that MPTCP gives a higher performance in terms of throughput, shorter download time, and increased bandwidth compared to Single Path TCP (SPTCP). The results from delivery of multimedia services using UHD HEVC- DASH streaming, though specific instead of general, reveal that under balanced and unbalanced network paths, MPTCP offers good Quality of Experience (QoE) compared to SPTCP. However, with variability in latency, and packet loss between paths, MPTCP underperforms compared to SPTCP in terms of video buffering in the unbalanced network case, and high packet retransmission rate in either balanced or unbalanced network paths.