43 research outputs found

    Radio communication via near vertical incidence skywave system

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    While the overall picture of our cutting-edge communication framework is one of high unwavering quality, the practical experience could be completely different during catastrophic situations, when communication services are disrupted due to damages in the communications infrastructure. Moreover, wireless connectivity in remote areas of the works is still a highly significant problem, with an estimated two billion people being outside of the connected world. This thesis studies the use of high frequencies communications as a way to address the abovementioned cases. High frequency (HF) communication utilizes radio waves between 3 and 30 MHz with the wavelengths of 100 to 10 m. The dominant means of long-distance communication in this band is skywave propagation, in which radio waves that are directed at an angle into the sky are reflected on Earth by the ionized layers of the atmosphere. HF ionospheric reflection technique is commonly used specifically for military, maritime, aeronautical, and emergency communication in remote areas, and as backup system. Factors such as season, sunspot cycle, solar activity, as well as polar aurora plays significant roles in the sustainability of HF radio communications. Propagation plays the most significant role while designing a communication network. Radio waves propagates with an objective of transmitting signal successfully without having an error. So, studies on wave propagation mechanisms, channel and noises are equally important. This thesis focuses on high frequency near vertical incidence skywave (HF NVIS) technology. NVIS, exploiting a frequency range of 2–10 MHz, can provide continuous coverage up to a couple of hundred kilometres from the transmitter without skip zone. NVIS operation is considered during disaster relief operations when infrastructure is severely damaged or where tactical communication is needed in military operations. NVIS operation requires the presence of substantial ionization in the ionosphere directly above the transmitter. For optimizing a NVIS communication system, the most important parameters to consider are elevation angle, fading, noise and polarization. Furthermore, NVIS operation requires careful selection of antennas, operating frequency, maximum usable frequency (MUF), lowest usable frequency (LUF), as well as frequency of optimum transmission (FOT) for successful communication. At the time of emergency, low data services such as voice and text could be easily established with NVIS system. A comprehensive overview of NVIS based on number of research articles is given which highlights ionospheric propagation, antennas, the operational use of HF communications, as well as applications. Further, we highlight the challenges with possible solutions, and future research direction to ensure NVIS system sustainability. From this literature review, the significant relationship between NVIS antenna and NVIS propagation mechanism is discussed. Furthermore, thesis provides a reference text to understand various elements of NVIS system and demonstrate how modern technology can be used to solve HF issues. We believe that this article will encourage more interests in addressing the technical challenges on the research and development of future HF radio communication systems

    Radio communication via near vertical incidence skywave system

    Get PDF
    Abstract. While the overall picture of our cutting-edge communication framework is one of high unwavering quality, the practical experience could be completely different during catastrophic situations, when communication services are disrupted due to damages in the communications infrastructure. Moreover, wireless connectivity in remote areas of the works is still a highly significant problem, with an estimated two billion people being outside of the connected world. This thesis studies the use of high frequencies communications as a way to address the abovementioned cases. High frequency (HF) communication utilizes radio waves between 3 and 30 MHz with the wavelengths of 100 to 10 m. The dominant means of long-distance communication in this band is skywave propagation, in which radio waves that are directed at an angle into the sky are reflected on Earth by the ionized layers of the atmosphere. HF ionospheric reflection technique is commonly used specifically for military, maritime, aeronautical, and emergency communication in remote areas, and as backup system. Factors such as season, sunspot cycle, solar activity, as well as polar aurora plays significant roles in the sustainability of HF radio communications. Propagation plays the most significant role while designing a communication network. Radio waves propagates with an objective of transmitting signal successfully without having an error. So, studies on wave propagation mechanisms, channel and noises are equally important. This thesis focuses on high frequency near vertical incidence skywave (HF NVIS) technology. NVIS, exploiting a frequency range of 2–10 MHz, can provide continuous coverage up to a couple of hundred kilometres from the transmitter without skip zone. NVIS operation is considered during disaster relief operations when infrastructure is severely damaged or where tactical communication is needed in military operations. NVIS operation requires the presence of substantial ionization in the ionosphere directly above the transmitter. For optimizing a NVIS communication system, the most important parameters to consider are elevation angle, fading, noise and polarization. Furthermore, NVIS operation requires careful selection of antennas, operating frequency, maximum usable frequency (MUF), lowest usable frequency (LUF), as well as frequency of optimum transmission (FOT) for successful communication. At the time of emergency, low data services such as voice and text could be easily established with NVIS system. A comprehensive overview of NVIS based on number of research articles is given which highlights ionospheric propagation, antennas, the operational use of HF communications, as well as applications. Further, we highlight the challenges with possible solutions, and future research direction to ensure NVIS system sustainability. From this literature review, the significant relationship between NVIS antenna and NVIS propagation mechanism is discussed. Furthermore, thesis provides a reference text to understand various elements of NVIS system and demonstrate how modern technology can be used to solve HF issues. We believe that this article will encourage more interests in addressing the technical challenges on the research and development of future HF radio communication systems

    An Overview on the Basics of Islamic Audit

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    Today is the age of globalization and business is considering as the leading global factor for social and   economic development. It is said that, Accounting is the language of business but it is another gigantic thought that Auditing is the side language of business. Audit is the vital factor to ensure the accountability of an organization, this paper events to explore audit on the perspective of Islam which further enables a practitioners and intended users to be self-confident and inspirational in using his or her acquired knowledge both in traditional system of auditing as well as Islamic perspective. The plot of the paper is as follows: In the first part we shall examine the development and approach of established auditing and point out some of its inadequacies from the Islamic point of view. In the last part, we shall state the role of auditing in the Islamic framework. Keywords: Islamic Auditing, Conventional Auditing, Islamic Shari’ah

    Development of a Framework for More Effective Implementation of Total Quality Management Principles in Apparel Manufacturing

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    The purpose of this paper is to develop a model or framework of total quality management (TQM) implementation in Textile and RMG industry. Textile and RMG Industry is an important sector for Bangladesh in terms of industrial expansion of the country, earning foreign currency and creating job opportunities. However, it faces subtle problems due to labor unrest, political instability and owner’s ignorance. TQM is an approach that focuses on customer satisfaction. Therefore, implementation of TQM is a challenging task. Through a self-administrative survey from 50 Industries of textile and RMG industry in Bangladesh data have been collected. This paper identifies ten key factors of TQM implementation in the Textile and RMG Industry in Bangladesh. These are Leadership, Communication, Strategic Quality Planning, Training, Customer Satisfaction, Continuous Improvement, Employee Involvement & Satisfaction, Culture, Supplier Satisfaction and Teamwork

    The impact of COVID-19 pandemic on mental health & wellbeing among home-quarantined Bangladeshi students: A cross-sectional pilot study.

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    BACKGROUND:COVID-19 is imposing threat both on physical and mental health since its outbreak. Bangladesh adopted lockdown strategy with potential consequences on day to day life, mental and physical health and this study aims to explore the impact of COVID-19 on mental health and wellbeing among Bangladeshi students. METHODS:A cross-sectional study was conducted between 9th and 23rd April 2020 among 505 college and university students. Data was collected by using online questionnaire including DASS 21 and IES. Descriptive analysis and bivariate linear regression were performed to examine the association of variables. RESULTS:28.5 % of the respondents had stress, 33.3% anxiety, 46.92% depression from mild to extremely severe, according to DASS 21 and 69.31% had event-specific distress from mild to severe in terms of severity according to IES. Perceiving physical symptoms as COVID-19 was significantly associated with DASS stress subscale (B = 3.71, 95% CI: 1.01 to 6.40), DASS anxiety subscale (B = 3.95, 95% CI: 1.95 to 5.96), DASS depression subscale (B = 3.82, 95% CI: 0.97 to 6.67) and IES scale (B = 7.52, 95% CI: 3.58 to 11.45). Additionally, fear of infection, financial uncertainty, inadequate food supply, absence of physical exercise and limited or no recreational activity had significant association with stress, anxiety, depression and post-traumatic symptoms. CONCLUSION:This COVID-19 outbreak imposes psychological consequences on people to a great extent which requires attention from the concerned authorities to cope with this situation mentally. The perception about the outbreak can also play a big role in psychological impact

    Achieving Bangladesh's Tourism Potential: Linkages to Export Diversification, Employment Generation and the 'Green Economy'

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    Bangladesh's international image is not as a popular tourism destination, and many people might be surprised to learn it has three World Heritage sites, including the Sundarbans tiger reserves. Moreover, it is part of important travel circuits for cultural and religious tourism, and has demonstrated potential for sports tourism. The objective of this working paper is to critically test the assertion that pro-poor "green" tourism is one of the best development options for the majority of least developed countries (LDCs) - a challenging task in Bangladesh in the face of the country's success as an exporter of readymade garments - by comparing tourism to the available alternatives with regard to the crucial government priorities of export diversification, employment generation and the "green economy". It is well-known that Bangladesh is under strong pressure to diversify its exports, to generate new employment (especially in rural areas), and to respond to critical environmental issues. The government has identified over 30 "thrust sectors" (including tourism) to help address these challenges, but otherwise tourism is rarely mentioned as a major trade and development option for Bangladesh. Within the limitations of data availability, this working paper reaches the conclusion that greater efforts to develop "green" tourism would be highly beneficial for facilitating rural development, environmental and cultural protection, gender equality, and export diversification in services. The most obvious current impediments are inadequate infrastructure, lack of investment and (typically election year) political conflict, but behind these factors appear to be a serious lack of stakeholder coordination, insufficient regulatory and administrative transparency and coherence, as well as some government reluctance to relinquish greater commercial autonomy in tourism to the private sector. This paper offers extensive analysis and some suggestions to help address the impediments, including the recommendation to create a Bangladesh Tourism Stakeholders Forum

    Socializing One Health: an innovative strategy to investigate social and behavioral risks of emerging viral threats

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    In an effort to strengthen global capacity to prevent, detect, and control infectious diseases in animals and people, the United States Agency for International Development’s (USAID) Emerging Pandemic Threats (EPT) PREDICT project funded development of regional, national, and local One Health capacities for early disease detection, rapid response, disease control, and risk reduction. From the outset, the EPT approach was inclusive of social science research methods designed to understand the contexts and behaviors of communities living and working at human-animal-environment interfaces considered high-risk for virus emergence. Using qualitative and quantitative approaches, PREDICT behavioral research aimed to identify and assess a range of socio-cultural behaviors that could be influential in zoonotic disease emergence, amplification, and transmission. This broad approach to behavioral risk characterization enabled us to identify and characterize human activities that could be linked to the transmission dynamics of new and emerging viruses. This paper provides a discussion of implementation of a social science approach within a zoonotic surveillance framework. We conducted in-depth ethnographic interviews and focus groups to better understand the individual- and community-level knowledge, attitudes, and practices that potentially put participants at risk for zoonotic disease transmission from the animals they live and work with, across 6 interface domains. When we asked highly-exposed individuals (ie. bushmeat hunters, wildlife or guano farmers) about the risk they perceived in their occupational activities, most did not perceive it to be risky, whether because it was normalized by years (or generations) of doing such an activity, or due to lack of information about potential risks. Integrating the social sciences allows investigations of the specific human activities that are hypothesized to drive disease emergence, amplification, and transmission, in order to better substantiate behavioral disease drivers, along with the social dimensions of infection and transmission dynamics. Understanding these dynamics is critical to achieving health security--the protection from threats to health-- which requires investments in both collective and individual health security. Involving behavioral sciences into zoonotic disease surveillance allowed us to push toward fuller community integration and engagement and toward dialogue and implementation of recommendations for disease prevention and improved health security

    Surface synthesization of magnesium alloys for improving corrosion resistance and implant applications

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    In the field of biodegradable material, a new research area has emerged for magnesium (Mg) and its alloys because of its high biocompatibility and biomechanical compatibility. This review summarizes many important types of research that have been done on degradable coatings on magnesium and its alloys for various implant applications. When magnesium alloys come into contact with other metals, they have a low open circuit potential and are consequently prone to galvanic corrosion. When exposed to air or a humid environment, magnesium may rapidly oxidize and generate a thin layer of loose MgO. Its applications were limited due to these drawbacks. Different types of corrosion have been studied in relation to magnesium and its alloys. Several coating methods are described, split into conversion and deposition coatings based on the individual processing procedures employed. This paper covers the most recent advancements in the development of biodegradable Mg alloy coatings over the last decade, revealing that the corrosion resistance of Mg and its alloys increases in most of circumstances due to coatings. Corrosion rate, coating morphology, adhesion, and surface chemistry were identified and explored as significant elements affecting coating performance. Calcium phosphate coatings made by deposition or conversion processes established for orthopedic purposes are the focus of many investigations according to a review of the literature. More research is needed on organic-based biodegradable coatings to improve corrosion resistance. Improved mechanical qualities are also crucial for coating materials. Developing adequate methodologies for studying the corrosion process in depth and over time is still a hot topic of research

    Advances of lithium-ion batteries anode materials—A review

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    Lithium-ion battery (LIB) research and development has witnessed an immense spike in activity in recent years due to the astonishing surge in demand for portable, environmentally acceptable energy sources across various industries. This need has resulted in a significant increase in the number of companies conducting LIB research and storing electrical energy and the intrinsic features that they contain. LIBs have become the go-to alternative for storing electrical energy in portable devices and electric vehicles. These properties include a lightweight structure, a high energy density, a small size, little memory effects, an extended lifespan, and environmental friendliness. Other advantages include a longer lifespan and a reduced impact on the environment. This review thoroughly examines energy storage technology changes. It shows the move away from environmentally harmful energy sources to greener ones. It highlights the need for creative energy storage options to match our rapidly changing technological world
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