Due to the spread of COVID-19 worldwide, a large number of universities had to close their campuses. To maintain teaching and learning during this disruption to the traditional teaching, most universities have adopted online teaching model. The current study aimed at investigating the efficacy of various online teaching modes as well as comparing a proposed combined model of online and flipped learning to other online and traditional models. The Learning under COVID-19questionnaire was designed and administered to undergraduate engineering students at Chengdu University of Information Technology (CUIT). The questionnaire included five parts: demographic questions, frequencies of online courses, types of online courses, the communication and Q&A in online classes and the effect of online classes, as well as the effect of combined model learning. The results of the study showed that, students were dissatisfied with online learning in general, and they were especially dissatisfied with the communication and Q&A modes. In addition, the combined model of online teaching with the flipped learning improved students' learning, attention, and evaluation of courses.

Abstract-In this paper, a triangular patch antenna (TPA) with 15 • -75 • -90 • angles is studied. The simulation results, using the full wave simulator, IE3D, for this TPA shape are compared with those for the equilateral triangular patch antennas (ETPA), the right angle isosceles triangular patch antenna (RAITPA), the 30

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As a result of the risks that waterborne bacteria bring to the human body, identifying them in drinking water has become a global concern. In this article, a highly sensitive surface plasmon resonance (SPR) biosensor consisting of prism, Ag, graphene, affinity layer and sensing medium is proposed for rapid detection of the waterborne bacteria. Four SPR‐based sensors are first studied with the structures prism/Ag/sensing medium, prism/Ag/affinity layer/sensing medium, prism/Ag/graphene/sensing medium, and prism/Ag/graphene/affinity layer/sensing medium. The latter structure is found to have the highest sensitivity so it is considered for further investigations. Four different commonly used prisms are then demonstrated which are N‐FK51A, 2S2G, SF10 and BK7. The structure with the prism N‐FK51A is found to correspond to the highest sensitivity so it is considered for further investigations. The structure parameters are then optimized. The proposed SPR sensor can achieve high sensitivity of about 221.63 °/RIU for Escherichia coli and 178.12 °/RIU for Vibrio cholera bacteria with an average value of 199.87 °/RIU. We believe that the proposed structure will open a new window in the field of microorganism detections.

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With the advances in the field of plasmonics, techniques for trapping and localizing light have become more feasible at the nanoscale. Several works have shown that plasmonics-based photovoltaic devices have yielded an improved absorption capability, enabling the design of thin-layered photovoltaic absorbers. In this review, we shed light on recent advances that employ plasmonics and nano-sized structures and thin-film technologies intended to increase solar cell efficiency. In this work, we provide an overview of the challenges associated with developing high-efficiency solar cells. Despite significant efforts by numerous groups to improve the efficiency of solar cells, practical realization of these concepts has yet to materialize. The conclusions made here hope to encourage researchers to re-examine the factors and challenges that could have created barriers to full realization of all concepts proposed over the past 15 years. In fact, because of the immense impact of improving the efficiency of solar cells on the environment and economy, it is hoped that this review encourages new technology paradigms that can be translated into commercially viable products.

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