Mobile Networks and Applications - In this paper, we study the performance of a full-duplex (FD) relay system in vehicle-to-vehicle (V2V) communication. In this relay communication system, the... 相似文献
Edge caching has received much attention as a promising technique to overcome the stringent latency and data-hungry challenges in the future generation wireless networks. Meanwhile, full-duplex (FD) transmission can potentially double the spectral efficiency by allowing a node to receive and transmit at the same frequency band simultaneously. In this paper, we investigate the delivery time performance of a cache-aided FD system, in which an edge node, operates in FD mode, serves users via wireless channels and is equipped with a cache memory. Firstly, we derive a closed-form expression for the average delivery time by taking into account the uncertainties of both backhaul and access wireless channels. The derived analysis allows the examination of the impact of key parameters, e.g., cache size and transmit power. Secondly, a power optimization problem is formulated to minimize the average delivery time. To deal with the non-convexity of the formulated problem, we propose an iterative optimization algorithm based on the bisection method. Finally, numerical results are presented to demonstrate the effectiveness of the proposed algorithm. A significant delivery time reduction is achieved by the proposed optimization compared to the FD reference and half-duplex counterpart.
Specific graphene architectures at the macroscopic scale are paramount for exploring new functions and practical uses of graphene. In this study, macroscopic, freestanding, and tubular graphene (TG) architectures were successfully fabricated through a versatile and robust process based on the annealing of cellulose acetate (CA) on Ni templates. These TG architectures can be obtained as woven tubes with diameters of approximately 50 μm; they possess high graphitic crystallinity, strong electrical conductivity, and favorable corrosion resistance. The effects of processing parameters, such as annealing temperature, annealing time, and amount of CA, on the graphene properties of these architectures were investigated and are discussed in this paper. The graphene properties were characterized through field emission scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy, four-point probe resistivity, and electrochemical measurements. 相似文献
In this paper, a zinc oxide (ZnO) nanotube, fabricated by the hydrothermal growth method on triple-junction (T-J) solar cell devices to enhance efficiency, is investigated. Compared to those of bare T-J solar cells (without antireflection (AR) coating) and solar cells with Si3N4 AR coatings, the experimental results show that the T-J solar cells, which use a ZnO nanotube as an AR coating, have the lowest reflectance in the short wavelength spectrum. The ZnO nanotube has the lowest light reflection among all experimental samples, especially in the range of 350 to 500 nm from ultraviolet (UV) to visible light. It was found that a ZnO nanotube can enhance the conversion efficiency by 4.9%, compared with a conventional T-J solar cell. The Si3N4 AR coatings also enhance the conversion efficiency by 3.2%.The results show that a cell with ZnO nanotube coating could greatly improve solar cell performances. 相似文献
We report the effect of temperature on the extent of graphene oxide reduction by hydrazine and the dispersibility of the resulting
chemically converted graphene (CCG) in polar organic solvents. The extent of graphene oxide reduction at high temperatures
was only slightly higher than at low temperatures (30–50 °C), while the dispersibility of the resulting CCG in organic solvents
decreased markedly with increasing temperature. The low dispersibility of CCGs prepared at high temperatures was greatly affected
by reduction and influenced by the formation of an irreversible agglomerate of CCG at high temperatures. The reduction of
graphene oxide at low temperatures is necessary to prepare highly dispersible CCG in organic solvents. CCG prepared at 30
°C is dispersible in N-methyl-2-pyrrolidone concentrations as high as 0.71 mg/mL. The free-standing paper made of this CCG
possessed an electrical conductivity of more than 22,000 S/m, one of the highest values ever reported. 相似文献