Papers by Keyword: Channel

Abstract: By adopting the first-principles calculation based on density functional theory (DFT), the diffuse pattern and the energy landscape for Li transfer in the LiFePO4 are investigated for the three different directions. The results of relaxed structure are compared with those of the non-relaxed structure and the energy barriers are significantly reduced and the effect of structure relaxation is most obvious for Li displacement along [100] direction. Energy barrier for the Li diffusion along [010] direction is lower than the other two direction in both calculation which indicates that the Li diffusion in LiFePO4 is one dimensional.

Abstract: Influences of arc-shaped baffles turbulators (ASB) on thermal behaviors in a solar air heater channel are studied. In the experiment, the ASB with three pitch ratios (P/e) are placed on the absorber plate (bottom channel wall in this case) to generate stronger turbulence intensity in the channel. The distributions of temperature and local Nusselt number contours in the absorber plate fitted with ASB are observed with thermochromic liquid crystal (TLC) sheet. The results reveal that the heat transfer increases with the decrease in P/e due to longitudinal vortex flow effect. The heat transfer from employing the ASB at P/e = 4.0, 6.0 and 8.0 is higher than the smooth channel around 116%, 120% and 127%, respectively. This indicates that the ASB pitch spacing is optimal at 8 times baffle height in the present work.

Abstract: This paper analyzes the characteristics of four kinds of possible channels in UHF RFID communication system, and makes a deep analysis on additive white Gaussian noise channel and binary symmetric channel. At the same time, it sets up the ASK modulation and demodulation simulation models of those two kinds of channels, summarizing the relationship between the bit error rate and the variety of signal to noise ratio of those two kinds of system. Finally, it concludes the optimal parameter of transmission process in the RFID system in experiments.

Abstract: In the campus WLAN wireless networks, transfer speed of network data is attracted great attention of users. How to solve conflict problem occurred in the network data transmission process has become the main goal of the campus WLAN network optimization. This paper presents campus WLAN wireless networks conflict resolution based channel mapping anti-collision algorithm. According to the amount of data to be transmitted in the network, the data length is estimated to provide conflict resolution with support data. On the basis of the channel mapping anti-collision algorithm related theory, conflict resolution model is established. Experimental results show that the proposed algorithm used in resolving conflict in campus WLAN wireless network can reduce the probability of data conflict happened in channel, so as to improve the performance of campus WLAN wireless network.

Abstract: In order to realize the accurate identification of the image color vegetable diseases in Greenhouse, In this paper, by using computer image processing technology in the intelligent recognition of vegetable diseases in greenhouse leaf, First, the moving average method can effectively remove the noise by the image of R,G, B three channel gray level, Then separate three channel image using Sobel-operator and the 4 template based on the direction of gradient magnitude ,and then integrate the three channel edge ,it can overcome the shortcoming of traditional gray image information, and make up the deficiency of the traditional Sobel operator edge thinning geometric features.

Abstract: The OFDM technology is applied in the mobile communication system of underground coal mine, the wireless communication system channel of underground coal mine is researched. The underground channel model is established, and the simulation is taken for testing the performance of system. The simulation results show that the OFDM technology can be applied in the mobile communication system in underground coal mine, and the transmission rate of the system and the ability of anti-interference are improved.

Abstract: This article presents the study of heat transfer enhancement in a uniform heat-fluxed channel fitted with discrete V-shaped baffles. The experiments are carried out by varying airflow rate for Reynolds number ranging from 4100 to 22,000. The V-baffles with relative height ratio, e/H = 0.15 and the attack angle, α = 45^o, are mounted repeatedly on the upper plate only, similar to an absorber plate of solar air heater systems. The effects of four baffle-pitch to channel-height ratios (PR= 0.5, 1.0, 1.5 and 2.0) on heat transfer in terms of Nusselt number and pressure loss in the form of friction factor are experimentally investigated. The experimental results show that the use of the discrete V-baffles leads to a considerable increase in Nusselt number and friction factor in comparison to the smooth channel alone. The V-baffled channel with PR=0.5 provides the highest heat transfer, friction factor and thermal enhancement factor.

Abstract: The South-to-North Water Transfer Project is a cross century water diversion project. So it is very important to ensure its normal operation. The hydraulic calculation of Jiping Canal of the South-to-North Water Transfer Project is carried out in this paper, working out cross section, the profile and the X-Y-Z perspective plot of Jiping Canal respectively. An analysis of the canal stability enables us to get the condition in which the canal is stable, which will provide strong technical support for the design and construction of the canal. Therefore, the analysis has important practical significance. The study will be effective guidance on the normal operation of Jiping Canal of South-to-North Water Transfer Project.

Abstract: Microfluidics offers methods of miniaturization for numerous chemical, electrochemical and biological processes. Thermal diffusion of molecular species through microfluidic channels is involved in many of such processes. High specific surface in microchannels complicates the theoretical assessment of diffusion rate in such channels as both the diffusion coefficient and the physisorption rate to the channel walls are temperature-sensitive. In this work, it is shown that both of these parameters vary in the same direction with temperature and the superposition of their respective effects makes the process rate highly temperature-sensitive. The molecular diffusion rates for three different molecular species, 2-butanol, tert-butanol and hydrogen, through a centimeter-long microchannel are experimentally monitored at the ambient temperature. Repeating such recording at different ambient temperatures facilitates the measurement and comparison of the temperature sensitivities of these processes. Among the fluids examined, those with lower diffusion coefficients showed more significant temperature dependences. The fabrication of the microfluidic system and the method utilized for monitoring the diffusion rate are also described in this paper.

Abstract: The MIMO technology, namely through many antenna clear signal transmission and the receive, in does not increase the extra band width under the premise, enhanced the channel capacity greatly. Understood the MIMO channel the characteristic, studies the channel modelling method, unified the FPGA parallel characteristic, the design has manufactured one kind based on XILINX FPGA the platform MIMO channel analog meter, through the massive test confirmation, and did with the theoretically simulation performance compares, has confirmed the accuracy.