Shenzhen University

About: Shenzhen University is a education organization based out in Shenzhen, China. It is known for research contribution in the topics: Computer science & Laser. The organization has 28054 authors who have published 35378 publications receiving 522023 citations.

Joint Power Allocation and Beamforming for Non-Orthogonal Multiple Access (NOMA) in 5G Millimeter Wave Communications

Abstract: In this paper, we explore non-orthogonal multiple access (NOMA) in millimeter-wave (mm-wave) communications (mm-wave-NOMA). In particular, we consider a typical problem, i.e., maximization of the sum rate of a 2-user mm-wave-NOMA system. In this problem, we need to find the beamforming vector to steer towards the two users simultaneously subject to an analog beamforming structure, while allocating appropriate power to them. As the problem is non-convex and may not be converted to a convex problem with simple manipulations, we propose a suboptimal solution to this problem. The basic idea is to decompose the original joint beamforming and power allocation problem into two sub-problems which are relatively easy to solve: one is a power and beam gain allocation problem, and the other is a beamforming problem under a constant-modulus constraint. Extension of the proposed solution from 2-user mm-wave-NOMA to more-user mm-wave-NOMA is also discussed. Extensive performance evaluations are conducted to verify the rational of the proposed solution, and the results also show that the proposed sub-optimal solution achieves close-to-bound sum-rate performance, which is significantly better than that of time-division multiple access.

Student enrollment, motivation and learning performance in a blended learning environment: The mediating effects of social, teaching, and cognitive presence

Abstract: This study investigated the effects of student enrolment and learning motivation on learning performance in a blended learning setting at the university level with social, teaching, and learning presence as mediating factors. Data samples were collected from 96 students taking blended learning course and 111 students taking a traditional course. The comparison between these two groups does not show a significant difference in the three presences and learning performance. Structural equation modelling results revealed that student enrolment has a positive impact on social presence and cognitive presence. Enrolment also positively influences learning performance through the above two presences. Learning motivation positively influence social presence only. Learning motivation also plays a vital role in enhancing the enrolment but does not directly influence learning performance in a blended learning setting. Teaching presence was found to have direct positive impacts on the cognitive presence and social presence, and indirect positive impacts on learning performance. These findings highlight the importance of student enrolment and course design from the teaching perspective in a blended learning setting.

New designs for phototherapeutic transition metal complexes

Abstract: In this Minireview, we highlight recent advances in the design of transition metal complexes for photodynamic therapy (PDT) and photoactivated chemotherapy (PACT), and discuss the challenges and opportunities for the translation of such agents into clinical use. New designs for light-activated transition metal complexes offer photoactivatable prodrugs with novel targeted mechanisms of action. Light irradiation can provide spatial and temporal control of drug activation, increasing selectivity and reducing side-effects. The photophysical and photochemical properties of transition metal complexes can be controlled by the appropriate choice of the metal, its oxidation state, the number and types of ligands, and the coordination geometry.

Flexible Asymmetrical Solid-State Supercapacitors Based on Laboratory Filter Paper

Abstract: In this study, a flexible asymmetrical all-solid-state supercapacitor with high electrochemical performance was fabricated with Ni/MnO2—filter paper (FP) as the positive electrode and Ni/active carbon (AC)—filter paper as negative electrode, separated with poly(vinyl alcohol) (PVA)–Na2SO4 electrolyte. A simple procedure, such as electroless plating, was introduced to prepare the Ni/MnO2–FP electrode on the conventional laboratory FP, combined with the subsequent step of electrodeposition. Electrochemical results show that the as-prepared electrodes display outstanding areal specific capacitance (1900 mF/cm2 at 5 mV/s) and excellent cycling performance (85.1% retention after 1000 cycles at 20 mA/cm2). Such a flexible supercapacitor assembled asymmetrically in the solid state exhibits a large volume energy density (0.78 mWh/cm3) and superior flexibility under different bending conditions. It has been demonstrated that the supercapacitors could be used as a power source to drive a 3 V light-emitting diode in...

High sensitivity and good selectivity of ultralong MoO3 nanobelts for trimethylamine gas

Abstract: In the present work, ultralong MoO3 nanobelts are prepared by a facile hydrothermal method, which are flexible with an average length of 200 μm and width of 200–400 nm. Gas sensor based on ultralong MoO3 nanobelts shows a remarkable gas sensing properties towards trimethylamine (TMA) from 100 °C to 380 °C with a humidity level of about 55%. The optimum operating temperature is 240 °C with a response of 582 to 50 ppm TMA in static mode. The selectivity test among various reducing gases shows that the sensor has a quite good response towards TMA if compared with others gases, such as ethanol, ammonia, toluene, methanol and acetone. The probable gas sensing mechanism of the prepared MoO3 nanobelts is discussed as well. The results indicate that this kind of sensor has a promising application in TMA detection.