Factors Influencing Students Engagement in Virtual Classrooms and Their Impact on Satisfaction

During the COVID-19 pandemic, many universities switched to virtual classrooms. Online learning has benefits, but faculty and students have to overcome barriers to adjust to this new educational process. This research explores the factors most influencing students engagement in online tertiary education, and examines their relation to instructors and students satisfaction. Following a broad literature review for the factors that may affect engagement in online learning in general and virtual classrooms in specific, a quantitative descriptive survey was designed and pilot-tested to examine the impact of the extracted factors on students engagement from the faculty and students’ perspectives. This self-reported questionnaire was then distributed via Microsoft Forms to 273 students and 109 faculty members (382 total respondents). The results showed that the most significant factors affecting students engagement from the perspectives of instructors and students are the behavioral and the learning-experience design. The results also revealed that satisfaction can be impacted greatly by only the technical factor and the behavioral factor from the instructors perspectives, however from the students perspectives it can be impacted by the psychological, behavioral, and learning experience deign factors

Discrete Element Modeling Of Railroad Ballast Under Simulated Train Loading

Ballasted tracks have been widely used in many countries around the world. Ballast layer is the main element in ballasted track. After service, ballast aggregates degrade and deform. Periodical maintenance for ballast layer is required; which is a cost and time expensive activity. Researchers used numerical approaches to understand the behavior of railroad ballast that leads to efficient design and maintenance. The Discrete Element Method (DEM) has been used increasingly to understand the mechanical behavior of railroad ballast, more frequently through box test. Most researches in the literature simulate the train loading as a pure continuous sinusoid based on train speed and axle spacing; unlike the actual loading induced by trains. This study aims to show the influence of simulated train loadings on ballast mechanical behavior using DEM via box test. The study utilizes the theory of Beam on Elastic Foundation to simulate a more realistic train load. The results from the more realistic simulated train load are compared with those from a sinusoidal load. The compared results highlight the influence of the simulated train load on the mechanical behavior of railroad ballast.Author: " I would like to acknowledge Qatar Rail for their sponsorship to this research under a project entitled “Framework for Research on Railway Engineering” with a grant reference number: QUEX-CENG-Rail 17/18.

A Numerical and Experimental Investigation of a Special Type of Floating-Slab Tracks

This thesis presents a research study on the dynamic behavior of a special type of FST used in recently built subway system in Doha, Qatar. The special FST has a continuous concrete slab with periodic grooves for which the track can be modeled as periodic structure with a slab unit having two elements with different cross sections. Extensive numerical and experimental investigations were conducted on a multi-unit full-scale mockup track. The numerical investigations were carried out using both a fast running model based on the Dynamic Stiffness Method and a detailed Finite Element model. In the experimental campaign, experimental vibration test was performed to identify the actual vibration response of the mockup track. Results from the experimental investigations were then used for verifying the numerical models and carrying out a model updating exercise for the fast running model. The model updating process was carried out according to an automated hybrid optimization approach. Finally, the updated model was extended to an infinite model and used in a parametric study to investigate the influence of varying groove’s thickness on the dynamic behavior of the special track with infinite length for both bending and torsion scenarios. The parametric study suggested that reducing the thickness below 50% of the full thickness of the slab significantly affects the dynamic behavior of the special FST

Comparison of the Mechanical Behavior of Railroad Ballast in a Box Test under Sinusoidal and Realistic Train Loadings Using Discrete Element Method

A ballasted track is a popular type of railway track and its use is increasing all over the world. A ballasted track consists of different structural elements like rails, fasteners, sleepers, ballast layer, sub-ballast layer and subgrade. A ballast layer is considered as the main structural element of ballasted tracks; it has a significant contribution to track stability and alignment. After service, periodical maintenance of ballast layer is required to maintain its functionality. Ballast maintenance is a cost and time expensive operation. Better understanding of ballast mechanical behavior leads to better ballast design and efficient maintenance. Discrete Element Method has been used extensively in the literature to understand the mechanical behavior of railroad ballast in a box test. Nevertheless, in the literature most of the studies simulate train loading as pure continuous sinusoidal loading unlike the real train loading. This paper aims to investigate the influence of the simulated train loading on the mechanical behavior of railroad ballast after 1000 loading cycles. There are two simulated train-loading cases used in this study for comparison purposes; continuous sinusoidal loading and a more realistic train loading utilizing the Beam on Elastic Foundation theory. The results show a difference of ballast vertical settlement up to 14% between the two simulated train-loading cases

Designing a W-type index praseodymium-doped chalcogenide fiber for strongly-efficient MIR Laser beyond 4 μm

This study is to propose an efficient design based on W-type index praseodymium (Pr 3+ )-doped chalcogenide fiber to enhance the emission of mid-infrared (MIR) wavelength beyond 4 μm. The advantage of the proposed design is to enlarge the core diameter to 32 μm under single mode guidance in order to restrict any impacts of nonlinearity and enhance the applied pumping power before the damage threshold. The effective mode field areas are about 979 μm 2 and 812 μm 2 at 4.5μm emitted MIR wavelength and 2.04μm pump wavelength, respectively. In the considered laser layout within this paper, a single pair of Fiber Bragg Gratings FBGs lay is adopted in the overlapping area of the emitting cross-sections parts of Pr 3+ ions in the transitions ( 3 F 2 , 3 H 6 → 3 H 5 and 3 H 5 → 3 H 4 ). This selected laser layout avoids the difficulties in the fabrication of concatenated FBGs in Pr 3+ -doped chalcogenide glass fibers. In addition, the efficiency of the laser can be also enhanced at this laser layout by emitting two photons in MIR wavelengths from one excited ion. The simulation outcomes indicate the possibility to exceed 61% of slope efficiency at 4.5 μm for 1dB/m loss in the fiber

HUMAN GENDER CLASSIFICATION USING KINECT SENSOR: A REVIEW

Human Gender Classification using Kinect sensor aims to classifying people’s gender based on their outward appearance. Application areas of Kinect sensor technology includes security, marketing, healthcare, and gaming. However, because of the changes in pose, attire, and illumination, gender determination with the Kinect sensor is not a trivial task. It is based on a variety of characteristics, including biological, social network, face, and body aspects. In recent years, gender classification that utilizes the Kinect sensor became a popular and essential way for accurate gender classification. A variety of methods and approaches, like machine learning, convolutional neural networks, sport vector machine (SVM), etc., have been used for gender classification using a Kinect sensor. This paper presents the state of the art for gender classification, with a focus on the features, databases, procedures, and algorithms used in it. A review of recent studies on this subject using the Kinect sensor and other technologies is provided, together with information on the variables that affect the classification\u27s accuracy. In addition, several publicly accessible databases or datasets are used by researchers to classify people by gender are covered. Finlay, this overview offers insightful information about the potential future avenues for research on Kinect-based human gender classification

An Approach to Calculate Exact Coverage Area for Connected Wireless Sensor Network

واحدة من التقنيات المتقدمة المستخدمة في أنظمة الاتصالات للشبكة الذكية هي شبكة الاستشعار اللاسلكية (WSN). WSN لديها مجموعة واسعة من التطبيقات تغطي العديد من المجالات مثل، إدارة الكوارث، اكتشاف حقل المعركة، التأمين على الحدود، مراقبة صحة المرضى، وغيرها. أن مشاكل الربط والتغطية للمستشعرات في الآونة الاخيرة لها أهمية عظيمة.  في البحث، قمنا بعرض الاتصال وتغطية العقد في WSN, تم اعداد خوارزمية لحساب مساحة التغطية المضبوطة لمجموعة عقد شبكة الاستشعار بالتوزيع المتجانس المستوي لنموذج القرص البسيط. هذه الخوارزمية تعتمد ارتباطات العقد ضمن مدى الاتصالات الاقصى للعقدة لذلك لايوجد في المساحات مناطق منفصلة. في حين تم احتساب كل المساحات غير المغطاة بالاستشعار ضمن المنطقة قيد الاهتمام (RoI) ضمن المساحة المغطاة. لذا تم احتساب النسبة المئوية للمساحة المغطاة بالضبط. ان استخدام هذه الطريقة سيكون الحجر الاساس للدراسات التي تتطلب سيطرة أفضل لنشر عقد المتحسسات. One of the advanced technologies used in the communicating systems of the intelligent grid is Wireless Sensor Network (WSN). WSN has a wide range of applications covers many fields like catastrophe management, hostilities field recognition, border insurance, patient health monitoring, and others. The sensor connectivity and coverage problems recently have a great attention. In this paper, we presented the connectivity and coverage of nodes in WSN, a new algorithm is prepared to extract exact coverage area of plain uniform depletion of node samples according to simple disk model. This algorithm considers the connection of nodes within maximum range of transmission communications, therefore no disconnected graph occurs. While uncovered area within region of interest (RoI) inside coverage area is calculated, although many uncovered regions occurred. So the coverage percentage area is calculated in an exact solution. This algorithm will be one of keystone study to better control of sensor depletion.    &nbsp

Green distributed algorithm for energy saving in IP wired networks using sleep scheduling

Energy saving has become a critical issue and a great challenge in the past few decades, and a great effort as well is being made to reduce consumed energy. The Internet forms a major source for energy consumption. Therefore, in this work we propose an algorithm for energy saving in distributed backbone networks, the reduced energy consumption (RedCon) algorithm. In this paper, we introduce a new version for saving energy on the Internet by switching off underutilized links and switching on idle links when the network is overloaded in a distributed manner over the network nodes based on LSA messages and without any knowledge of the traffic matrix. Our algorithm is more accurate and outperforms other algorithms with its time checks and advanced learning algorithm