Department of Electrical Engineering
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Item Nowcasting of RSSL in wireless communication channel over the sea using machine learning algorithms(COMSATS University Islamabad Lahore Campus, 0023) Farwa Jafar,; FA20-REE-005; Dr. Khurram Zaidi; LHR TP 7896The presence of naturally occurring evaporation duct (ED) phenomenon is very high in the tropical/equatorial regions of the world. Although, refractivity estimation of EM and Radio waves in ED is well studied in the literature, still, the signal propagation through ED over-the-horizon needs to be thoroughly researched to help determine the received-signal-strength-level (RSSL) for a reliable wireless communication link. In order to accurately predict RSSL in ED, we have acquired RSSL (avg.) per-minute data for three months over-the-horizon distance of 50 km (Tx-Rx) from onshore-to-offshore Oil & Gas Platform. This data was collected using fixed antenna heights in ED. Applying deep learning algorithms on real-time RSSL data, we have nowcasted the future RSSL values for next 5 seconds timescale in this thesis. A thorough comparison is made between the CNN and LSTM deep learning methods for real-time series prediction analysis. These deep learning networks are linked with numerous convolution layers to grasp the nonlinear mapping between measured and future RSSL values. Coding and Simulation work is performed in Python 3.9 environment and results are generated in Kaggle Notebook. CNN and LSTM networks have never been used earlier for predicting “signal strength” over-the-horizon and over-the-sea under ED environment. The contribution of this research is to bridge this gap and examine the accuracy of LSTM and CNN for nowcasting RSSL data. According to what we've discovered, both of these neural network models are capable of achieving adequate to high prediction power given that the "datasets" are suitably big. Both methods, when taken as a whole, are reliable with regard to their hyperparameters. However, with increasing number of training courses, LSTM didn’t improve its performance, whereas CNNs performed correspondingly more accurate each time. For 3rd training, CNN has given the most optimal fitting of training data as compare to test data. The RMSE achieved for CNN after third training was 4.47 which is the least of all simulations. Hence, CNNs proved to be superior, since they operate one order of magnitude quicker than LSTM. We proposed that the early predictive capability, speed, and resilience of CNN open its door to nowcasting’s future.Item Module level power electronics in distrubted power system for solar PV application(COMSATS University Islamabad Lahore Campus, 0022) Muhammad Talha Naveed; , SP20-REE-015; Dr. Muhammad Yaqoob Javed; LHR TP 7895hotovoltaic (PV) solar energy is as promising as other renewable energies. Different researchers and engineers are attempting to increase the efficiency of solar PV system. As a result, for PV modules, this enhancement may be accomplished at almost the same level. As is well known, solar PV systems are less efficiency as a result of changing climatic conditions. Module-level power electronics (MLPE) do this by providing the performance improvements of a distributed transmission system in both partial and full shading conditions. As a result, MLPE successfully harvests the distributed maximum power point (DMPP) from solar to accept DC from PV or the grid. Each PV module is connected to the power system via a separate dc/dc converter with Maximum Power Point Tracking (MPPT) capabilities in the DMPP scheme. Each PV panel has a built in power optimization or micro-inverter that helps it work better in partial shade. In order to design the MLPE the efficiency of contemporary string inverters are comparing. The efficiency may be measured in a variety of situations, including uniform irradiation and partial shade. As a result, a DC-DC converter that is attached to each PV module is required to offset shading losses. The optimizer identifies the Local peak using a DC-DC converter from the unit, shuts down the modules during fire situations, troubleshoots, and monitoring a module in a highly efficient manner in this work. On the Matlab software tool, the effectiveness of the proposed power optimizer is displayed. To calculate efficiency, several firms such as SMA, Solar Edge, Huawei, Tigo, and Enphase can use helioscope to compare production and loses data. The results suggest that MLPE produces superior outcomes.Item Active Fault Tolerant Control Scheme For Dissimil(COMSATS University Islamabad Lahore Campus, 2018) Ghazala Mushtaq, FA16-REE-016 Contributor(s): Dr. Mirza Tariq Hamayun, Assistant Profesor [Supervisor]; LHR TP 7474The increasing demand of Fault Tolerant Control (FTC) schemes in research is due to reliability and safety needed in industrial systems, especially in life critical systems such as spacecraft, passenger aircrafts, Unmanned Aerial Vehicle (UAV), nuclear and chemical plants. FTC is expected to deal with fault or failure while maintaining the stability and desired performance. It is classified as Passive Fault Tolerant Control (PFTC) and Active Fault Tolerant Control (AFTC). Dissimilar Redundant Actuating Systems (DRAS) are mostly used in modern aircrafts to improve the reliability by evading the Common Mode/Common Cause (CM/CC) failure issue of similar redundant actuating systems. DRAS consists of two actuators i.e. Hydraulic Actuator (HA) and Electro Hydraulic Actuators (EHA). The DRAS are operated in two different modes namely active/active (A/A) mode and Active/Passive (A/P) mode. In A/P mode, the HA actively involve controlling the concerned control surface while the EHA and control surface act as a load to HA while in A/A mode, both actuators are engaged in controlling the control surface at the same time resulting in a force fighting exist between them that can even damage the control surface if the actuators are not synchronized. A lot of research has been carried out on DRAS in different operating modes and a significant contribution has been made to improve its stability. This thesis is about an AFTC scheme for modern aircrafts equipped with DRAS in A/A mode to affirm the reliable actuation and efficient control. The dynamics of both actuators of DRAS are considered that gives the desired control surface deflection. The force fighting issue of actuators being in A/A mode, is also addressed in this research. The effect of fault or failure of HA on system performance is analyzed and an Integral Sliding Mode Controller (ISMC) is designed which together with Control Allocation scheme (CA) improves the system performance at different fault severity level.Item Output Feedback FTC Scheme For Linear Parameter(Publisher COMSATS University Islambad Lahore Campus, 2016) Izhar Ul Haq; , FA13-MSEE-006; Dr. Mirza Tariq Hamayun, Assistant Profesor [Supervisor]; LHR TP 6820The proposed research has been carried out for an Active Fault Tolerant Control (FTC) of Linear Parameter Varying (LPV) systems using output feedback mechanism. Output feedback is a practical approach due to the fact that all the plant states are not accessible or measurable, therefore estimating the unknown states and maintaining the closed loop stability in an LPV framework is closer to the control of nonlinear systems. At the same time, it utilizes the mature nature of linear control theory. In this research, LPV observers in LMI framework have been designed for affine LPV plant, using two different LPV approaches namely affine and polytopic, in order to estimate the unknown states. These estimated states are used as a feedback to LPV controller. Integral sliding mode controller in LPV framework has been designed along with control allocation scheme to control the controlled states as well as to counter for actuators faults and failures. It has been assumed that Fault Detection and Isolation unit, also called FDI, is providing updated actuator faults or failures information to the control allocation (CA) scheme. Detailed performance and stability of the proposed control scheme has been checked in fault-free case, i.e. nominal condition, as well as in the situation when actuator fault occurs. To validate the proposed output feedback FTC mechanism, an LPV model of longitudinal plant of aircraft, taken from the literature, has been considered as a benchmark in the simulation. The simulation results show that the system is quadratically stable and give good tracking capability by the LPV controller-observer pair in nominal as well as in actuator’s fault or failure situation.Item Design Of Hemispherical Antenna For Breast Cancer(Publisher COMSATS University Islambad Lahore Campus, 2017) Iqra Asghar,; SP15-REE-005; Dr. Asim Ali Khan, Assistant Profesor [Supervisor]; LHR TP 6824Microwave imaging has proven to be successful for medical imaging applications including breast cancer, lungs cancer, brain stroke detection, cardiac imaging etc. Microwave imaging has the ability to detect malignancy present at depth of tissue, providing non-invasive imaging, measuring dielectric contrast between tissues. This imaging procedure provides an effective substitute of mammography, ultrasound or MRI as all these screenings provide unreliable and uncomfortable detection. In this thesis, microwave imaging system has been simulated for breast tumor detection. The designed microwave imaging system includes the use of holographic imaging. For the design of holographic imaging array, two-dimensional (2D) and three-dimensional (3D) breast models have been designed in MATLAB. Holographic array simulations have been carried out in MATLAB. To efficiently reconstruct an image, inverse scattering algorithm has been applied in holography imaging array. The building block of microwave imaging is to design a suitable antenna that must efficiently transmit and receive electromagnetic signals. An efficient compact double layer antenna has been designed in HFSS for the breast malignancy detection system. The antenna provides good impedance matching, wide bandwidth, stable and symmetric radiation pattern for near field imaging. To improve the performance of imaging system, the antenna was simulated in an array configuration. To overcome the drawbacks of array system, a novel array topology has been simulated in HFSS. The designed array system consists of separate transmitters and receivers for imaging, to provide low cost, reliable and effective detecti