Study and Implementation of Wideband Bow-Tie Antennas

Demand for multifunctional electronic devices is increasing in modern wireless communication systems. As the antenna plays a vital role in wireless communication, the need to design antennas which will provide better performance and more reliable communication is growing. In this thesis, innovative designs for antennas with wideband characteristic have been proposed to meet the demands of current multi-functional wireless communication systems. First, this thesis explores the design of a wideband pattern reconfigurable antenna with steady realized gain over the operating bandwidth. Another novel design of this thesis work is a highly directive wideband Yagi antenna. Finally, a two-planar structured CPLPDA antenna is designed to overcome the currently existing three-planar structured CPLPDA antenna’s complex design and fabrication process

Analysis of Human Affect and Bug Patterns to Improve Software Quality and Security

The impact of software is ever increasing as more and more systems are being software operated. Despite the usefulness of software, many instances software failures have been causing tremendous losses in lives and dollars. Software failures take place because of bugs (i.e., faults) in the software systems. These bugs cause the program to malfunction or crash and expose security vulnerabilities exploitable by malicious hackers. Studies confirm that software defects and vulnerabilities appear in source code largely due to the human mistakes and errors of the developers. Human performance is impacted by the underlying development process and human affects, such as sentiment and emotion. This thesis examines these human affects of software developers, which have drawn recent interests in the community. For capturing developers’ sentimental and emotional states, we have developed several software tools (i.e., SentiStrength-SE, DEVA, and MarValous). These are novel tools facilitating automatic detection of sentiments and emotions from the software engineering textual artifacts. Using such an automated tool, the developers’ sentimental variations are studied with respect to the underlying development tasks (e.g., bug-fixing, bug-introducing), development periods (i.e., days and times), team sizes and project sizes. We expose opportunities for exploiting developers’ sentiments for higher productivity and improved software quality. While developers’ sentiments and emotions can be leveraged for proactive and active safeguard in identifying and minimizing software bugs, this dissertation also includes in-depth studies of the relationship among various bug patterns, such as software defects, security vulnerabilities, and code smells to find actionable insights in minimizing software bugs and improving software quality and security. Bug patterns are exposed through mining software repositories and bug databases. These bug patterns are crucial in localizing bugs and security vulnerabilities in software codebase for fixing them, predicting portions of software susceptible to failure or exploitation by hackers, devising techniques for automated program repair, and avoiding code constructs and coding idioms that are bug-prone. The software tools produced from this thesis are empirically evaluated using standard measurement metrics (e.g., precision, recall). The findings of all the studies are validated with appropriate tests for statistical significance. Finally, based on our experience and in-depth analysis of the present state of the art, we expose avenues for further research and development towards a holistic approach for developing improved and secure software systems

Numerical simulation & risk analysis of well kick

Oil and gas development is moving into harsh and remote locations where the highest level of safety is required. A blowout is one of the most feared accidents in oil and gas developments projects, which is the result of uncontrolled flow of influx into the wellbore. Limited insights about the rapidly changing physical parameters during a blowout necessitates the exhaustive analysis of kick detection parameters. The risk of blowout consequences can be minimized by appropriate kick detection and well control techniques. This work presents a dynamic numerical simulation of kick detection and experimental studies to analyze hydrodynamic properties of drilling fluid to detect a kick. The experimental results are used to verify dynamic numerical simulation results. A three dimensional CFD simulation of a pressure cell which is a mimic of a scaled down version of a wellbore is performed using commercial CFD package ANSYS Fluent-15. The main objective of this simulation model is to analyze the pressure gradient, rising speed of a gas kick and volumetric behaviour of the gas kick with respect to time. Simulation results exhibit a sudden increase of pressure while the kick enters and volumetric expansion of gas as it flows upward. This improved understanding helps to develop effective well control strategies. The proposed numerical simulation model is validated by comparison with experimentally obtained downhole pressure during an influx into the pressure cell. This study confirms the feasibility and usability of an intelligent drill pipe as a tool to monitor well condition and develop blowout risk management strategies. Furthermore, to quantify the risk of blowout consequences, this work aims to test and validate a blowout risk assessment model using uniquely developed experimental results. Kick detection is a major part of the blowout risk assessment model. The accuracy and timeliness of kick detection are dependent on the monitoring of multiple downhole parameters such as downhole pressure, fluid density, fluid conductivity and mass flow rate. In the present study these four parameters are considered in different logical combinations to assess the occurrence of kick and associated blowout risk. The assessed results are compared against the experimental observations. It is observed that simultaneous monitoring of mass flow rate combined with any one the three parameters provides most reliable detection of kick and potential blowout likelihood. This work confirms that a blowout risk model integrated with real time monitoring is a reliable and effective way of managing blowout risk. Upon success testing of this approach at the pilot and field levels, this approach could provide a paradigm shift in drilling safety

Assessing Public Perception and Proposing an Organized Questionnaire for the Deployment and Adoption of Autonomous Vehicles

Since the general public will play a central role in the evolution of AVs, research has been performed to assess their perception and acceptance of AVs. Nevertheless, the most potential users of AVs, i.e., young, students, and more educated people, have not received any particular focus in those studies. This research gap has motivated us to assess their perceptions. Extensive data analyses of the survey at the University of Central Florida with a sample of 315 reveal that on average 57% of the respondents were familiar with AVs, and about 44% of the respondents felt positive perceptions toward AVs. Around 51% of the respondents had some concerns regarding the perceived negative aspects of AVs, however, a significant percentage of people (around 34%) maintained a neutral position regarding the negative aspects of AVs. In addition, structural equation modeling was performed considering five latent variables and 32 observed variables to investigate the inter-relationship among those variables. Model results suggest that as more people have positive primary perceptions about different aspects of AVs, their attitudes toward AVs would be more positive, and the concerns regarding AVs would be reduced. Demographic characteristics do not significantly influence the willingness to possess AVs, and people want to own AVs despite their different demographic backgrounds. These study findings could help policymakers to apprehend different prospects of people\u27s perceptions regarding AVs and have implications for the stakeholders of autonomous vehicles. In addition to that, the study proposed an organized questionnaire based on which the responses of the stakeholders should be collected and analyzed. Findings from literature using heterogeneous questionnaires produced perplexing results for making relevant policies for the adoption and deployment of AVs. The current study addressed this research gap. Particularly this study attempted to identify the organizational pattern of the questionnaire of the previous studies, and eventually proposed a uniform questionnaire based on which future studies might be conducted to obtain varying outcomes from different contexts for the same input. The proposed questionnaire is divided into two portions: a) general content, and b) special content. The general content is applicable to all studies that seek to assess the perceptions of people regarding AVs. This content consists of 4 main categories i.e., perceptions, concerns, expected benefits, and ownership. In addition to general content, special content is also proposed to be added with the general content for some specific cases where the studies will focus on Shared AVs (SAVs) or investigate the perceptions of vulnerable road users or assess the perceptions of the respondents after riding AVs. The current study has the potential to help future studies produce effective policy measures for the quick adoption and deployment of AVs

The Effect of Management by Objectives on Performance Appraisal and Employee Satisfaction in Commercial Banks

Management by Objectives (MBO) is one of the most effective performance appraisal method widely used in the organization. This study deals with the effect of Management by Objectives on performance appraisal and employee satisfaction.  A self-administered questionnaire was used to judge the perception of the employees regarding MBO and its effect on their performance appraisal and employee satisfaction. The number of participants included in the survey was 60 employees from 33 commercial banks at Rajshahi Division in Bangladesh. This study aims to identify the respondent’s demographic profile such as age, education, salary, and banking experience and reveals the importance of MBO on their performance appraisal and employee satisfaction. IBM SPSS v23.0 program has been used to analyze the questionnaire. Descriptive analysis, Pearson correlation analysis, and Regression analysis used to test the hypotheses. Econometric results suggest that MBO should be used as a method of performance appraisal and most of the commercial banks use Management by Objectives as an effective tool. In our correlation analysis we found performance appraisal and employee satisfaction have a significant positive relationship (r=0.715). Performance appraisal increase employee satisfaction. Employee satisfaction increase productivity and effectiveness in the organization. Proper reward mechanism increase satisfaction level of the employees. Keywords: Commercial Banks, Employee Satisfaction, Management by Objectives, Organizational Effectiveness and Performance Appraisal. DOI: 10.7176/EJBM/12-20-02 Publication date:July 31st 202

Topas based high birefringent and low loss single mode hybrid-core porous fiber for broadband application

We present a through numerical analysis of a low loss and highly birefringent hybrid porous core with octagonal cladding structure for terahertz (THz) wave guidance. The proposed photonic crystal fiber (PCF) offers simultaneously low effective material loss (EML) as well as high birefringence in the frequency range of 0.8-1.05 THz with single mode operation. To attain high birefringence we introduce asymmetry in the core using both elliptical and circular air holes (hybrid). The numerical results obtained from the finite element method (FEM) which confirms low EML of 0.044 cm–1 as well as a high birefringence of ~0.043 at 0.73 THz operating frequency. Therefore, the fiber is likely to be useful in different THz polarization maintaining applications

Experimental investigation on the properties of concrete containing post-consumer plastic waste as coarse aggregate replacement

The consumption of various forms of plastic has been increased in recent days due to the boost in industrialization and other human activities. Most of the plastic wastes are abandoned and require large landfill area for storage. More importantly, the low biodegradability of plastic poses a serious threat to environment protection issue. Various methods have been followed for the disposal of plastic in an attempt to reduce the negative impact of the plastic on the environment. Recently, various types of plastic have been incorporated in concrete to minimize the exposure of plastic to the environment. The aim of this study is to investigate the properties of concrete containing polyethylene terephthalate (PET), and high density polyethylene (HDPE) plastic that were used as partial replacement of coarse aggregate (CA). In this study, four compositions of stone aggregate(S): plastic waste ratios have been used by volume basis: 100% S: 0% Plastic (control concrete), 90% S: 10% PET, 90% S: 10% HDPE, and 90% S: 5% PET+5% HDPE. The effects of waste plastic addition on the mechanical properties of concrete are presented in this paper. Test results reveal that minimum reduction in compressive strength has been found 35% in case of 10% PET plastic replaced concrete whereas splitting tensile strength for 10% PET replaced concrete has been increased by 21% while compared to control concrete. In addition, fresh unit weight of concrete containing plastic waste has been decreased by 4% in comparison to control concrete

Low loss topas based porous core single mode photonic crystal fiber for THz communications

In this paper, an extremely low loss hybrid hexagonal porous core and octagonally structured circular cladding photonic crystal fiber (PCF) for low loss terahertz (THz) wave propagation has been designed and proposed.  We have analyzed ultralow effective material loss (EML), high core power fraction and ultra-flattened dispersion in our proposed design. To investigate the transmission characteristics, perfectly matched layer (PML) is used in the outer boundary of the PCF. At an operating frequency of 1 THz, this design exhibits a low effective material loss of 0.045 cm-1 at a high core power fraction of 58.2% with 88% porosity. The proposed PCF shows dispersion variation of 0.225 ps/THz/cm. Also, this designed PCF can operate in single-mode condition successfully. It is anticipated that designed PCF can be employed in applications such as fiber optics communications, sensing and spectroscopy