Analysis and Compensation of Power Amplifier Distortions in Wireless Communication Systems

Wireless communication devices transmit message signals which should possess desirable power levels for quality transmission. Power amplifiers are devices in the wireless transmitters which increase the power of signals to the desired levels, but produce nonlinear distortions due to their saturation property, resulting in degradation of the quality of the transmitted signal. This thesis talks about the analysis and performance of communication systems in presence of power amplifier nonlinear distortions. First, the thesis studies the effects of power amplifier nonlinear distortions on communication signals and proposes a simplified design for identification and compensation of the distortions at the receiver end of a wireless communication system using a two-step pilot signal approach. Step one involves the estimation of the channel state information of the wireless channel and step two estimates the power amplifier parameters. Then, the estimated power amplifier parameters are used for transmitter identification with the help of a testing procedure proposed in this thesis. With the evolution of millimeter wave wireless communication systems today, study and analysis of these systems is the need of the hour. Thus, the second part of this thesis is extended to study the performance of millimeter wave wireless communication systems in presence of power amplifier nonlinear distortions and derives an analytical expression for evaluation of the symbol error probability for this system. The proposed analysis evaluates the performance of millimeter wave systems theoretically without the need of simulations, and is helpful in studying systems in the absence of actual hardware

A prospective, open label clinical study to evaluate the safety, efficacy and tolerability of azadvir herbal steam inhaler in asymptomatic, mildly symptomatic COVID-19 patients and health care workers posted to covid wards

Background: COVID-19 patients experience cytokine storm which cause pulmonary and extra-pulmonary complications even with currently available of standard of care. Additional antiviral and immune boosters are the need of hour to treat COVID-19 and to prevent post covid complications.Methods: In this study we enrolled 40 asymptomatic to mild COVID-19 patients to receive azadvir herbal steam inhaler along with standard of care. We evaluated the benefits of azadvir herbal steam inhaler by assessing RT-PCR conversion, clinical outcomes and improvement in immune markers (LDH, CRP, D-DIMER).Results: At the end of the study the immune markers improved significantly in study patients. In mild symptomatic cases IL-6 was 23.2 pg/ml on day 0 and 21.8 pg/ml on day 14. Reduction in IL-6 in mild symptomatic patients was statistically highly significant (p=0.0056). Mean IL-6 in asymptomatic patients was 22.3 pg/ml on day 0 and 21.1 pg/ml on day 14. Reduction in IL-6 in asymptomatic patients was statistically highly significant (p=0.0035).  Mean D-dimer was showing decreasing trend from day 0 to day 14 in mild symptomatic patients. In asymptomatic patients D dimer was 0.8 µg/ml on day 0 and 0.6 µg/ml on day 14. D-dimer decreased significantly from day 0 to day 14 (p value =0.0013). Mean LDH values on day 0 in mild symptomatic patients was 319.4 U/l and 219.3 on day 14. The reduction in LDH values in mild symptomatic patients is statistically significant (p value <0.0122). In asymptomatic patients mean LDH values on day 0 was 237 U/l and 194 U/l on day 14. The reduction in LDH values in asymptomatic group was statistically significant. Mean CRP values in mild symptomatic patients on day 0 was 12.2 mg/l and 3.8 mg/l on day 14. There was significant reduction in CRP values in mild symptomatic group which was statistically significant (p value =0.0546). Mean CRP values in asymptomatic patients on day 0 was 4.9 mg/l and 2.8 mg/l on day 14. There was significant reduction in mean CRP in asymptomatic patients which was statistically significant (p value =0.0446). In the present study all 40 patients (100%) cleared the virus and became negative for RT PCR test within 6 days. None of the patients progressed to severe COVID-19 and none of the patients succumbed to the disease.Conclusions: Azadvir accelerated recovery of COVID-19 patients by RT-PCR conversion, early improvement in clinical symptoms and immune markers in this study. This study results clearly indicates that azadvir has antiviral, immune booster activity and has definitive role in the management of asymptomatic to mild COVID-19 patients along with standard of care (CTRI no. CTRI/2020/06/026181)

Detection of covid 19 from an imbalanced chest x-ray image data set

The Covid-19 pandemic has spread quickly, making identification of the virus critically important in assisting overburdened healthcare systems. Numerous techniques have been used to identify Covid-19, of which the Polymerase chain reaction (PCR) test is the most common. However, obtaining results from the PCR test can take up to two days. An alternative is to use X-ray images of the subject’s chest area as inputs to a deep learning neural networks algorithm. The two problems with this approach are the choice of architecture and the method used to deal with the imbalanced data. In this study a comparative analysis of a standard convolutional neural network (CNN) and a number of transfer learning algorithms with a range of imbalanced data techniques was conducted to detect Covid-19 from a data set of chest x-ray images. This data set was an amalgamation of two data sets extracted from the Kaggle Covid-19 open source data repository and non-Covid illnesses taken from the National Institute of Health. The resulting data set was had over 115k records and 15 different type of findings ranging from no-illness to illnesses such as Covid-19, emphysema and lung cancer. This study addresses the problem of class imbalance on the largest data set used for x-ray detection of Covid-19 by combining undersampling and oversampling methods. The results showed that a CNN model in conjunction with these random over and under sampling methods outperformed all other candidates when identifying Covid-19 with a F1-score of 93%, a precision of 90% and a recall of 91%

Photobiomodulation With Customized Insoles on Maximum Plantar Pressure in Diabetic Foot Syndrome by the Biomechanical Model: A Case Report

A 49-year-old male patient with type 2 diabetes mellitus and Diabetic Foot Syndrome (DFS) was evaluated by comprehensive diabetic foot assessment. A 10-session photobiomodulation therapy (low-level laser therapy) was prescribed for neuropathic pain and symptoms applying the scanning and probe method. Customized insoles were recommended for redistributing the plantar pressures and reducing stress on the diabetic foot’s plantar surface for 4 weeks. Dynamic plantar pressure distribution, lower limb kinematics, and postural sway were evaluated using WinTrack dynamic pressure platform. Photobiomodulation therapy with customized insoles is useful in the redistribution and treatment of plantar pressure and gait kinematics. This approach should be extensively used in DFS as preventive and treatment measures

Investigation of Mechanical Properties of Sisal Fiber Reinforced Polymer Composites

The aim of this work is to study the influence of sisal fiber content on mechanical (i.e. tensile, flexural, impact, hardness and abrasion resistance) and thermal (i.e. TGA) properties of composites by varying the fiber and epoxy percentage. The composite was prepared by melt-mixing method, followed by compression molding process. The percentage of sisal fiber is varied from 4% to 10% in steps of 2%. Similarly epoxy content is varied from 96% to 90% in steps of 2%. Detailed mechanical Properties of Sisal Fiber Reinforced Polymer Composites have been studied. The major mechanical properties viz Tensile, Hardness, Impact, Flexural, Moisture absorption, and Moisture content are studied

3rd National Conference on Image Processing, Computing, Communication, Networking and Data Analytics

This volume contains contributed articles presented in the conference NCICCNDA 2018, organized by the Department of Computer Science and Engineering, GSSS Institute of Engineering and Technology for Women, Mysore, Karnataka (India) on 28th April 2018