The COVID-19 pandemic has forced many organizations around the world to make full use of a variety of emerging online communication platform technologies. Universities are among the organizations that have asked students, tutors, and lecturers to use a number of different online communication platforms to ensure the education process remains uninterrupted. However, the COVID-19 pandemic has generated considerable challenges for the global higher education community while using such emerging technologies. This research has two main goals. First, this paper will begin by investigating whether the online learning platforms used by university students during the COVID-19 period have presented any challenges to their learning. Second, the paper will then go on to address proposed solutions by developing a conceptual model to reduce the impact of such challenges. This research uses an exploratory qualitative research approach, supported by literature content analysis techniques. The data set for this study was collected during the first peak of the pandemic period in Malaysia, between the 16th of May 2020 and the 5th of June 2020. We used SPSS to conduct a descriptive analysis and NVivo12 to analyse data collected from 486 students from different universities in Malaysia. These students disclosed various obstacles they encountered when they used IT platform applications for online learning. These obstacles include (a) work and information overload received from instructors, (b) inadaptability and unfamiliarity of the new online learning environment, and (c) personal health challenges related to stress and anxiety. Based on previous relevant research, this study introduced a set of motivational factors and developed a conceptual motivational model for sustainable and healthy online learning.

The COVID-19 pandemic has forced many organizations in the world to fully utilize variety of emerging online communication platform technologies. Higher Education Institutions (HEIs) are among these organizations that obliged students and instructors to use different online communication platforms to insure uninterrupted education process. However, the COVID-19 pandemic has generated many considerable challenges for the global higher education community while using such emerging technologies. The purpose of this study is to analyze university student’s perceptions on the challenges and hurdles they face during the Covid-19 pandemic when they use IT platform applications for online learning activities. This research used mixed methods research with main emphasis on qualitative research, supported by literature content analysis techniques. The data set for this study was collected during peak time of pandemic period between 16^th of May 2020 to 5^th of Jun 2020. Based on the descriptive analysis using SPSS and the analyzed results using NVivo12 for the data that was collected from 486 students from different universities in Malaysia, students disclosed various obstacles they encounter when they use IT platform applications for online learning. These obstacles are summarized as follows: (1) Work and information overload received from instructors through online learning platforms (2) Technical challenges related to students’ lack of affordability for having online learning support facilities (3) Personal health challenges related to stress and anxiety problems.

In the electric power distribution system, power electronics technologies associated with renewable energy systems (RES) and smart grids have gained growing interest. The power electronics devices are used to convert, control, or transfer electric power from RES to the power grids. However, the continuous increase in switching frequencies resulting from these power electronics technologies has led to the emergence of new emissions in the range of 2-150 kHz, outside the classical frequency range for power quality. These emissions are known worldwide as supraharmonics (SH).These emissions negatively affect the power quality of electrical distribution systems and reduce their efficiency and lifetime. Thus, the supraharmonics emissions have been investigated in the literature, and several methods were developed focusing on identifying, measuring, and setting new standards to mitigate the impact of these emissions on the power quality. Although these individual studies have been well documented, a comparative overview of its identifications, current standards, and measurement techniques had not been described so far. Therefore, this study extensively reviews the related techniques and standards for identifying, measuring, and mitigating SH emissions. Moreover, the current research gap in this important field is highlighted, and an illustration on how this problem was tackled in the past few years is presented. Additionally, the SH characteristics alongside with insights into the mitigations and measurements are highlighted and analyzed accordingly. Finally, some important recommendations to mitigate SH emissions are suggested. This review will hopefully strengthen the efforts toward the development of SH domain by providing the necessary groundwork for further mitigations, standards, and measuring techniques improvement. INDEX TERMS Grid integration; harmonics emissions; high frequency; power quality; renewable energy sources; supraharmonics.

In future 5G systems, the millimeter wave (mmWave) band will be used to support a large capacity for current mobile broadband. Therefore, the radio access technology (RAT) should be made available for 5G devices to help in distinct situations, for example device-to-device communications (D2D) and multi-hops. This paper presents ultra-wideband channel measurements for millimeter wave bands at 19, 28, and 38 GHz. We used an ultra-wideband channel sounder (1 GHz bandwidth) in an indoor to outdoor (I2O) environment for non-line-of-sight (NLOS) scenarios. In an NLOS environment, there is no direct path (line of sight), and all of the contributed paths are received from different physical objects by refection propagation phenomena. Hence, in this work, a directional horn antenna (high gain) was used at the transmitter, while an omnidirectional antenna was used at the receiver to collect the radio signals from all directions. The path loss and temporal dispersion were examined based on the acquired measurement data—the 5G propagation characteristics. Two different path loss models were used, namely close-in (CI) free space reference distance and alpha-beta-gamma (ABG) models. The time dispersion parameters were provided based on a mean excess delay, a root mean square (RMS) delay spread, and a maximum excess delay. The path loss exponent for this NLOS specific environment was found to be low for all of the proposed frequencies, and the RMS delay spread values were less than 30 ns for all of the measured frequencies, and the average RMS delay spread values were 19.2, 19.3, and 20.3 ns for 19, 28, and 38 GHz frequencies, respectively. Moreover, the mean excess delay values were found also at 26.1, 25.8, and 27.3 ns for 19, 28, and 38 GHz frequencies, respectively. The propagation signal through the NLOS channel at 19, 28, and 38 GHz was strong with a low delay; it is concluded that these bands are reliable for 5G systems in short-range applications.

Mode division multiplexing (MDM) is a promising technology for increasing the aggregate bandwidth of multimode fiber (MMF) in conjunction with wavelength division multiplexing (WDM) in face of the impending capacity crunch in optical fiber networks. This paper investigates the effect of radial and azimuthal mode spacings in a 25-channel MDM-WDM system in MMF using a spatial light modulator-controlled VCSEL array for excitation of Laguerre-Gaussian (LG) modes. A data rate of 25Gbps is achieved at a central wavelength of 1550.12 nm. The effects of different azimuthal and radial mode spacings of LG modes are analyzed in terms of the channel impulse response, eye diagram and bit-error rate.