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Online Education in HEIs in Bangladesh moderated by COVID-19: Modified UTAUT2 受COVID-19影响的孟加拉国高等学校在线教育:修改后的UTAUT2
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.197
S. Khan, Nurakmal Ahmad Mustaffa, M. Habib
The whole world, including Bangladesh is brought to a standstill by the pandemic of COVID-19.  All the hustling-bustling of a densely populated country has come to a quiescent halt; the only sound remaining is the whisper of anxiety. The HEIs in Bangladesh is also struggled to react to this sudden catastrophe; magnified by uncertainties.  Compared to public universities, the private universities of the country managed to react the fastest and are making sweeping changes in a very short period of time, shifting traditional face-to-face course content/teaching to online content/teaching. The shift to fully functional online teaching learning platform was sudden and with minimum preparation. To investigate the perception of the private universities community in Bangladesh with this new teaching learning method, this paper adopted the Unified Theory of Acceptance and Use of Technology (UTAUT) model, focuses on stakeholders’ behavioral intention, availability of the online platform, prior experience, attitude towards usage (ease of use and usefulness) and most importantly the impact of COVID-19 pandemic. Additionally, the paper also discusses the issues of social and cultural impact. It was found that all the UTAUT attributes are positively correlated with the Behavioral Intention and eventually to Use Behavior of students in adopting online education. Moreover, unexpected, and unprecedented impact of COVID-19 pandemic also effected their behavioral intention towards accepting online education.
包括孟加拉国在内的整个世界都被COVID-19大流行所困扰。在这个人口稠密的国家,一切熙熙攘攘的喧嚣都安静地停止了;唯一剩下的声音是焦虑的低语。孟加拉国的高等教育机构也在努力应对这场突如其来的灾难;被不确定性放大了。与公立大学相比,该国的私立大学反应最快,并在很短的时间内进行了彻底的改变,将传统的面对面课程内容/教学转变为在线内容/教学。向功能齐全的在线教学平台的转变是突然的,几乎没有准备。为了调查孟加拉国私立大学社区对这种新的教学方法的看法,本文采用了技术接受和使用统一理论(UTAUT)模型,重点关注利益相关者的行为意图、在线平台的可用性、先前的经验、对使用的态度(易用性和有用性),最重要的是COVID-19大流行的影响。此外,本文还讨论了社会和文化影响的问题。研究发现,所有UTAUT属性都与学生接受在线教育的行为意向和最终使用行为呈正相关。此外,出乎意料的、前所未有的疫情影响也影响了他们接受在线教育的行为意愿。
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引用次数: 3
Energy Harvesting Technology by Converting Waste Heat Energy from Automobiles 利用汽车余热转化的能量收集技术
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.180
Md. Abdullah Al Rakib, Md. Saniat Rahman Zishan, Md. Abid Hasan Abid
In this project, heat energy is used for generatingelectrical energy by a conversion process. The energy harvestingfrom the heat of motorbike has become a new source of portableenergy for rechargeable gadgets. In contrary, the conventionalnonrenewable energy sources have likewise added to anexpansion in contamination on the planet and a disintegration ofhuman wellbeing. From the electrical energy, the mobile phonewill be charged. A thermoelectric generator has been connectedto the hot portion of the motorbike and while riding the bike, anykind of chargeable device will get charged. The prototype of thisresearch work has effectively harvested electrical energy fromheat using thermoelectric generator and has managed to provideenough power at different speeds of the motorbike.
在这个项目中,热能被用于通过转换过程产生电能。从摩托车的热量中收集能量已经成为可充电设备的一种新的便携式能源。相反,传统的不可再生能源同样加剧了地球上污染的扩大和人类福祉的瓦解。从电能中,手机将被充电。一个热电发电机已经连接到摩托车的发热部分,当骑自行车时,任何可充电的设备都可以充电。这项研究工作的原型利用热电发电机有效地从热量中收集电能,并设法在不同速度的摩托车上提供足够的电力。
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引用次数: 0
FRT and Transient Stability Augmentation of Grid-Connected PV Station Using Virtual Synchronous Generator 利用虚拟同步发电机增强并网光伏电站的FRT和暂态稳定
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.171
M. Islam, M. Mannan, Md. Rifat Hazari
Due to the extensive integration of renewable energy sources (RESs), i.e., photovoltaic (PV) system, the future power system is developing into an inverter-based system from a dominated alternator-based power system. This massive penetration of inverter-based PV system reduced the system inertia and damping characteristics of the power grid, impacting the fault ride-through (FRT) capability and causes frequency instability. Modern grid codes require that PV systems should work in the same way as conventional power plants and assist the system during transient state. However, most of the conventional inverter control mechanisms failed to fulfill the requirements of grid codes, especially when the penetration ratio of the PV system is close to the conventional unit. Therefore, this paper proposes a virtual synchronous generator (VSG) control mechanism of PV system inverter to augment FRT competency and frequency stability. The proposed VSG control system mimics the behavior of conventional power plants. To observe and evaluate the proposed controller behavior, simulation analyses were executed in the PSCAD/EMTDC software for both proposed and conventional controllers. The simulation results clearly indicate that the proposed VSG control system has sufficient damping characteristics to ensure FRT capability and frequency stability.       
由于可再生能源(RESs)即光伏(PV)系统的广泛集成,未来的电力系统正从以交流发电机为主的电力系统向以逆变器为主的电力系统发展。基于逆变器的光伏系统的大规模渗透降低了电网的系统惯性和阻尼特性,影响了故障穿越(FRT)能力并导致频率不稳定。现代电网规范要求光伏发电系统应以与传统电厂相同的方式工作,并在暂态状态下辅助系统。然而,传统的逆变器控制机制大多不能满足电网规范的要求,特别是当光伏系统的渗透比接近常规机组时。为此,本文提出了一种光伏系统逆变器的虚拟同步发电机(VSG)控制机制,以增强其FRT能力和频率稳定性。所提出的VSG控制系统模拟了传统电厂的运行行为。为了观察和评估所提出的控制器的行为,在PSCAD/EMTDC软件中对所提出的控制器和传统控制器进行了仿真分析。仿真结果清楚地表明,所提出的VSG控制系统具有足够的阻尼特性,以保证FRT能力和频率稳定性。
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引用次数: 0
Integrated Mobile Learning Education Supply Chain Management for Higher Learning Institution 高校集成移动学习教育供应链管理
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.289
Mashiour Rahman, R. A. Rahman, M. Habib
The mobile devices are used to execute the teaching-learning-evaluation process in Mobile Learning (m-learning) methodology. M-learning is a trending field in educational organizations, companies, and for individual study. With the explosion of mobile device ownership among the users aged within 18–29 years who are also the attendees of the higher learning institution (HLI), gives us the opportunity to consider the use of m-learning methodology to be embedded in the HLI beside traditional methodologies. Exceptional circumstances such as the COVID-19 pandemic when traditional face-to-face methodology suddenly changed to online paradigm, is also forcing us to strongly consider the m-learning approach. However, HLI may not have a general policy to implement m-learning into the traditional learning environment. A proper educational outcome needs to be configured to implement a new process into the traditional process. Therefore, a model integrating the m-learning aspects and the education supply chain management factors obtained from this study may benefit the stakeholders of HLI, especially educators and students.
在移动学习(m-learning)方法中,使用移动设备来执行教学-学习-评估过程。移动学习在教育机构、公司和个人学习中是一个趋势领域。随着18-29岁用户中移动设备所有权的爆炸式增长,这些用户也是高等教育机构(HLI)的参与者,这使我们有机会考虑将移动学习方法嵌入传统方法之外的HLI中。像COVID-19大流行这样的特殊情况,传统的面对面学习方法突然转变为在线范式,也迫使我们强烈考虑移动学习方法。然而,HLI可能没有在传统学习环境中实施移动学习的一般政策。需要配置一个适当的教育结果,以便在传统过程中实现一个新的过程。因此,从本研究中获得的整合移动学习方面和教育供应链管理因素的模型可能有利于HLI的利益相关者,特别是教育者和学生。
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引用次数: 1
Study and Analysis of Photonic Crystal Fiber for Broadband Laser Source Design 用于宽带激光光源设计的光子晶体光纤的研究与分析
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.200
M. Faisal, Sk. M. Jahangir Kabir
Photonic Crystal Fiber (PCF) has been a topic of extensive research in the field of nonlinear fiber optics. It is due to its combination of linear and nonlinear properties which ultimately results in the phenomenon having various types of applications. One of the phenomena is supercontinuum generation that has been extensively studied numerically and experimentally over the last few decades as it has important applications in the field of medical imaging and sensing. In this paper, we numerically analysed and studied PCF of hexagonal core with various parameters and propose our novel ‘Star in Hexagon’ design as a good candidate for the broadband supercontinuum generation and hence a broadband laser source. We numerically pumped a long 10 mm PCF of this kind at 3.1 um wavelength with a pulse having a power of 4000 W and a temporal width of 50 fs. A broadband supercontinuum ranging from 1.7 um to 18 um was obtained. The generated spectrum is quite well in the mid-infrared region. Hence it can be utilised for Mid – Infrared (MIR) applications.
光子晶体光纤(PCF)是非线性光纤领域中一个广泛研究的课题。正是由于它的线性和非线性特性的结合,最终导致了这种现象具有各种类型的应用。其中一种现象是超连续统的产生,由于它在医学成像和传感领域有重要的应用,在过去的几十年里得到了广泛的数值和实验研究。在本文中,我们数值分析和研究了不同参数的六角形核心的PCF,并提出了我们的新颖的“六角形星”设计作为宽带超连续谱产生的良好候选者,从而成为宽带激光源。我们在3.1 um波长处用功率为4000 W、时间宽度为50 fs的脉冲数值泵浦了一个长10 mm的这种PCF。得到了1.7 ~ 18 μ m的宽带超连续谱。生成的光谱在中红外区域相当好。因此,它可以用于中红外(MIR)应用。
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引用次数: 0
A PLS-SEM Approach to Connect Fertility, GDP, and Childhood Mortality with Female life Expectancy (FLE) in Bangladesh PLS-SEM方法将生育率、GDP和儿童死亡率与孟加拉国女性预期寿命(FLE)联系起来
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.210
M. Ahmmed, M. Babu, M. A. Hoque, M. M. Rahman
A reasonable number of studies on the effect of Female life expectancy (FLE) upon the quality of women's lives in developed countries have been done. Bangladesh lacks such a study. We explore the effect of decreasing fertility and childhood mortality rates on FLE in Bangladesh and evaluate the potential impthe act of the demographic transition on GDP. Also, we investigate the trends and patterns of different factors from 1995 to 2018. Partial Least Squares-Structural Equation Modeling (PLS-SEM) is functioned to fit an appropriate model to link fertility, GDP, and childhood mortality with FLE. The significance of the relationships has also been assessed. Results indicate that declines in fertility and childhood mortality have made significant improvements in FLE. The prospects of demographic transition due to fertility decline have been analyzed, and challenges to achieve it are highlighted.
已就发达国家妇女预期寿命对妇女生活质量的影响进行了相当数量的研究。孟加拉国缺乏这样的研究。我们探讨了孟加拉国生育率和儿童死亡率下降对儿童死亡率的影响,并评估了人口结构转变对GDP的潜在影响。此外,我们还研究了1995 - 2018年不同因素的变化趋势和格局。偏最小二乘-结构方程模型(PLS-SEM)的作用是拟合一个适当的模型,将生育率,GDP和儿童死亡率与FLE联系起来。这些关系的重要性也被评估了。结果表明,生育率和儿童死亡率的下降使FLE得到了显著改善。分析了生育率下降导致的人口转型的前景,并强调了实现这一目标所面临的挑战。
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引用次数: 3
Review of Different Error Metrics: A Case of Solar Forecasting 不同误差度量的回顾:以太阳预报为例
Pub Date : 2021-12-30 DOI: 10.53799/ajse.v20i4.212
Pardeep Singla, M. Duhan, Sumit Saroha
Renewable energy systems (RES) are no longer confined to being used as a stand-alone entity in the modern era. These RES, especially solar panels are also used with the grid power systems to supply electricity. However, precise forecasting of solar irradiance is necessary to ensure that the grid operates in a balanced and planned manner. Various solar forecasting models (SFM) are presented in the literature to produce an accurate solar forecast. Nevertheless, each model has gone through the step of evaluation of its accuracy using some error measures. Many error measures are discussed in the literature for deterministic as well as probabilistic solar forecasting. But, each study has its own selected error measure which sometimes landed on a wrong interpretation of results if not selected appropriately. As a result, this paper offers a critical assessment of several common error metrics with the goal of discussing alternative error metrics and establishing a viable set of error metrics for deterministic and probabilistic solar forecasting. Based on highly cited research from the last three years (2019-2021), error measures for both types of forecasting are presented with their basic functionalities, advantages & limitations which equipped the reader to pick the required compatible metrics
在现代,可再生能源系统(RES)不再局限于作为一个独立的实体使用。这些可再生能源,特别是太阳能电池板也与电网电力系统一起使用来供电。然而,太阳辐照度的精确预测是必要的,以确保电网以平衡和有计划的方式运行。各种太阳预报模型(SFM)提出了在文献中产生一个准确的太阳预报。然而,每个模型都经过了使用一些误差度量来评估其准确性的步骤。对于确定性和概率太阳预报,文献中讨论了许多误差措施。但是,每个研究都有自己选择的误差测量方法,如果选择不当,有时会对结果产生错误的解释。因此,本文对几种常见误差指标进行了批判性评估,目的是讨论可选的误差指标,并为确定性和概率性太阳预报建立一套可行的误差指标。基于过去三年(2019-2021)被高度引用的研究,本文介绍了两种预测的误差测量方法及其基本功能、优势和局限性,使读者能够选择所需的兼容指标
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引用次数: 4
Multi-Modal Case Study on MRI Brain Tumor Detection Using Support Vector Machine, Random Forest, Decision Tree, K-Nearest Neighbor, Temporal Convolution & Transfer Learning 基于支持向量机、随机森林、决策树、k近邻、时间卷积和迁移学习的MRI脑肿瘤检测多模态案例研究
Pub Date : 2021-09-26 DOI: 10.53799/ajse.v20i3.175
P. Sutradhar, Prosenjit Kumer Tarefder, Imran Prodan, Md. Sheikh Saddi, Victor Stany Rozario
In the Medical field, Brain Tumor Detection has become a critical and demanding task because of its several shapes, locations, and intensity of image. That’s why an automated system is important to aid physicians and radiologists in detecting and classifying brain tumors. In this research, we have discussed different machine learning as well as deep learning algorithm which are mostly used for image classification. We have also compared different models that are being used for tumor classification based on machine learning and deep learning. MRI images of Glioma tumor, Pituitary tumor, Meningioma tumor are the base of this research, and we have compared different techniques along with the accuracy of different classification models using those MRI images. We have used different deep learning pre-trained models for training the brain tumor images. Those pre-trained models have provided outstanding performance along with less power consumption and computational time. EfficientNet-B3 has provided the best accuracy of 98.16% among other models as well as traditional machine learning algorithms. The experimental result of this model is proven the best and most efficient for tumor detection and classification in comparison with other recent studies.
在医学领域,脑肿瘤的检测由于其不同的形状、位置和图像强度而成为一项关键而艰巨的任务。这就是为什么自动化系统对帮助医生和放射科医生检测和分类脑肿瘤很重要。在本研究中,我们讨论了不同的机器学习和深度学习算法,这些算法主要用于图像分类。我们还比较了用于基于机器学习和深度学习的肿瘤分类的不同模型。胶质瘤、垂体瘤、脑膜瘤的MRI影像是本研究的基础,我们比较了不同的技术以及使用这些MRI影像的不同分类模型的准确性。我们使用了不同的深度学习预训练模型来训练脑肿瘤图像。这些预训练的模型提供了出色的性能以及更少的功耗和计算时间。在其他模型和传统的机器学习算法中,EfficientNet-B3提供了98.16%的最佳准确率。实验结果表明,该模型对肿瘤的检测和分类是最有效的。
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引用次数: 4
Linearization of High frequency Class E Feedback Amplifier using Negative Impedance Method 高频E类反馈放大器的负阻抗线性化
Pub Date : 2021-09-23 DOI: 10.53799/ajse.v20i3.166
Md. Shoaib Sikder, M. Tanseer Ali
This work represents a novel method of linearization of Switch Mode Power Amplifier (SMPA). For this purpose, class E SMPA was designed and analyzed both before and after applying a linearization technique known as Negative Impedance method. One of the major characteristics of a standard SMPA is that they poses high efficiency than their linear counterpart but on the other hand they show highly nonlinear characteristics. The motivation behind this work is to harness this highly efficient amplifier and make it linear which can very useful for various applications in RF communication fields. All the schematics and simulations that are presented in this paper was performed using Cadence Virtuoso environment using “Spectre” simulator tool. For active components, 280nm process technology was used under “gpdk90” pdk which based on BSIM3v3 model. Circuit was designed to run at 2GHz with 2.5 V supply voltage. A mathematical model is also presented using data found from the analysis, with the help of MATLAB. Linearity was measured using Input referred Intercept Point of 3rd order frequency (IIP3), which was improved from 3.7dBm to 17.86dBm with 57% percent efficiency providing an output power of 15.78dBm.
本文提出了一种新颖的开关功率放大器线性化方法。为此,在应用负阻抗法线性化技术前后,对E级SMPA进行了设计和分析。标准SMPA的一个主要特点是比线性SMPA具有更高的效率,但另一方面又表现出高度的非线性特性。这项工作背后的动机是利用这种高效放大器并使其线性化,这对于射频通信领域的各种应用非常有用。本文给出的所有原理图和仿真都是在Cadence Virtuoso环境下使用“Spectre”仿真工具进行的。对于有源元件,采用基于BSIM3v3模型的“gpdk90”pdk下的280nm制程技术。电路设计工作在2GHz,电源电压为2.5 V。利用分析得到的数据,在MATLAB的帮助下建立了数学模型。利用三阶频率的输入参考截距点(IIP3)测量线性度,从3.7dBm提高到17.86dBm,效率为57%,输出功率为15.78dBm。
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引用次数: 0
Impact of COVID-19 on Academic and Psychological aspects of Undergraduate Students in Bangladesh: A Case Study 2019冠状病毒病对孟加拉国大学生学业和心理方面的影响:个案研究
Pub Date : 2021-09-23 DOI: 10.53799/ajse.v20i3.169
M. Ahmmed, M. M. Rahman, Abhijit Bhowmik, A. Siddiqua
Undergraduate students are considered susceptible in terms of anxiety, drug abuse, depression, and bad dietary habits in comparison to the general people. Their academic and psychological facets have severely been altered due to COVID-19 pandemic. The objective of this study is to identify the effect of COVID-19 on the academic and psychological aspects of undergraduate students in Bangladesh accompanied by other pertinent factors. Data were accumulated from the undergraduate students of the Fall semester 2020-21 of American International University-Bangladesh (AIUB) by questionnaire provided through Microsoft Forms. The associations among the variables were assessed through the chi-square test. All the statistical analyses required to meet the goals of the study were done through Statistical Package for Social Sciences (SPSS). Nearly one-fourth of the students suffered from anxiety and depression at an extreme level while close to one-third of them suffered quite a bit signaling a tormenting psychological state of the students. Chi-square tests found that depression, anxiety, study hour, assessment of online learning, and income issue due to COVID-19 of the student had a highly significant association with effects on their study and psychological aspects. Failure to address the aforesaid issues during an epidemic might have negative consequences on the academic and psychological aspects in the long run.
与一般人相比,大学生被认为在焦虑、滥用药物、抑郁和不良饮食习惯方面容易受到影响。由于新冠肺炎大流行,他们的学术和心理方面都发生了严重变化。本研究的目的是确定COVID-19对孟加拉国本科生学术和心理方面的影响以及其他相关因素。通过微软表格提供问卷调查,收集了来自孟加拉国美国国际大学(AIUB) 2020-21秋季学期本科生的数据。通过卡方检验评估变量之间的相关性。为了达到研究的目标,所有的统计分析都是通过社会科学统计软件包(SPSS)完成的。近四分之一的学生极度焦虑和抑郁,近三分之一的学生极度焦虑和抑郁,这表明学生的心理状态非常痛苦。卡方检验发现,学生的抑郁、焦虑、学习时间、在线学习评估、因新冠肺炎导致的收入问题与他们的学习和心理方面的影响有高度显著的关联。在流行病期间不解决上述问题,从长远来看可能对学术和心理方面产生负面影响。
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引用次数: 3
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AIUB Journal of Science and Engineering (AJSE)
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