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排序方式: 共有2819条查询结果,搜索用时 140 毫秒
1.
This paper proposes a comprehensive thermodynamic and economic model to predict and compare the performance of concentrated solar power plants with traditional and novel receivers with different configurations involving operating temperatures and locations. The simulation results reveal that power plants with novel receivers exhibit a superior thermodynamic and economic performance compared with traditional receivers. The annual electricity productions of power plants with novel receivers in Phoenix, Sevilla, and Tuotuohe are 8.5%, 10.5%, and 14.4% higher than those with traditional receivers at the outlet temperature of 550°C. The levelized cost of electricity of power plants with double-selective-coated receivers can be decreased by 6.9%, 8.5%, and 11.6%. In Phoenix, the optimal operating temperature of the power plants is improved from 500°C to 560°C by employing a novel receiver. Furthermore, the sensitivity analysis of the receiver heat loss, solar absorption, and freeze protection temperature is also conducted to analyze the general rule of influence of the receiver performance on power plants performance. Solar absorption has a positive contribution to annual electricity productions, whereas heat loss and freeze protection temperature have a negative effect on electricity outputs. The results indicate that the novel receiver coupled with low melting temperature molten salt is the best configuration for improving the overall performance of the power plants. 相似文献
2.
This study details the numerical modelling and optimization of natural convection heat suppression in a solar cavity receiver with plate fins. The use of plate fins attached to the inner aperture surface is presented as a possible low cost means of suppressing natural convection heat loss in a cavity receiver. In the first part of the study a three-dimensional numerical model that captures the heat transfer and flow processes in the cavity receiver is analyzed, and the possibilities of optimization were then established. The model is laminar in the range of Rayleigh number, inclination angle, plate height and thickness considered. In the second part of the study, the geometric parameters considered were optimized using optimization programme with search algorithm. The results indicate that significant reduction on the natural convection heat loss can be achieved from cavity receivers by using plate fins, and an optimal plate fins configuration exit for minimal natural convection heat loss for a given range of Rayleigh number. Reduction of up to a maximum of 20% at 0° receiver inclination was observed. The results obtained provide a novel approach for improving design of cavity receiver for optimal performance. 相似文献
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针对宽带调制解调技术中广泛存在的IQ不平衡问题,在IQ不平衡模型及补偿原理的分析基础上提出了一种宽带数字接收机IQ不平衡估计与自适应补偿算法。首先利用解调数据对IQ不平衡参数进行实时估计,然后利用估计参数对接收信号进行自适应补偿。实验结果表明,所提算法可以有效解决宽带调制解调系统中普遍存在的IQ不平衡问题,提升系统误码性能。 相似文献
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Bekir Sami Yilbas 《国际能源研究杂志》2019,43(2):616-620
Surface cleaning remains essential for the sustainable operation of high performance solar thermal receivers. Cleaning of optical surfaces, such as solar troughs and absorbers, requires energy intensive efforts because of the large surface area involvement such as those observed in solar farms. In addition, self‐cleaning of such surfaces becomes demanding because of lowering the cleaning costs, reducing the waste of resources, such as clean water, and minimizing the complication of the mechanical systems incorporated. Self‐cleaning of surfaces is associated with the low adhesion between the surface and the foreign particles; in which case, these particles can be removed easily from the surfaces in a cost‐effective way. The surface energy and contact area of the surface are two main important parameters influencing the particle adhesion on the surfaces. In this case, reducing the surface energy and forming micro/nano size pillars on the surface through texturing lower the particle adhesion on the surfaces significantly. In solar thermal energy harvesting applications, metallic or composite materials are used and texturing the surface remains challenging in terms of cost and precision of operation when conventional texturing methods are used. One of the methods to create surface texture consisting of micro/nano pillars is to use the laser beam ablation. This results in hierarchical distribution of surface texture with desired pillar heights1. In addition, laser surface texturing offers significant advantages over the conventional techniques. Some of these advantages include fast processing, precision of operation, and low cost. Although the laser processing involves with high temperature processing and thermally induced stresses remain important, the defects sites can be minimized via controlling the process parameters during the texturing. Introducing the assisting gas on the texturing surface enables to generate compounds such as oxide or nitride species, which lower the surface energy considerably. Consequently, investigation of laser texturing of solar energy materials while incorporating the assisting gas becomes essential. In the present perspective, the laser surface texturing of solar energy materials for thermal power applications is presented together with challenges and future perspectives. Specifically, the followings will be presented: (1) the texture characteristics of laser treated metallic and ceramic surfaces; (2) wetting state of the textured surface, and optical properties of textured surface in terms of absorption of the solar irradiation. 相似文献
8.
瑞利波分析方法及应用进展 总被引:15,自引:4,他引:15
介绍了瑞利波平面及轴对称分析方法,这两种方法对数值模拟场地信号、实测频散曲线及研究各阶振型瑞利波频散曲线十分重要。用二维傅里叶变换或多次滤波,在一定程度上可将信号中瑞利波不同振型分离,得到不同振型频散曲线,而用相位差或互相关分析方法得到的频散曲线可认为是各阶振型瑞利波频散曲线加权平均.瑞利波频散曲线与半无限体分层介质力学参数有关,通过对频散曲线正、反分析可得到各层介质力学参教.此外,还介绍了瑞利波在地下目的物探测中的应用。 相似文献
9.
Jingjing Liu Yimin Zhou Grahame E. Faulkner Dominic C. O'Brien Steve Collins 《International Journal of Circuit Theory and Applications》2015,43(7):840-853
The ability to create and direct beams of light means that optical communications potentially offer a large power advantage over RF communications for sensor networks. This paper presents an optically powered receiver front end for wireless optical communications. A complete optical receiver front end including a photodetector, clock and Manchester data recovery circuits has been fabricated using the UMC 180 nm CMOS process. A novel modulation scheme is described that has been devised so that this front end can recover the clock and Manchester data from an optical beam. Experimental results show that the total current consumption of the optical receiver front end is as low as 18.8 nA for a 0.5 V supply when a 1 kbps Manchester data and 8 kHz clock signal are successfully recovered. This means that photodiodes on the same substrate as the front end circuits extract enough power from the communications beam to allow the front end to work at distances of up to 10 m from the transmitter. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
10.
Mo Huang Dihu Chen Zhao Wang Jianping Guo Elias H. Dagher Bin Xu Ken Xu Hui Ye Weiguo Zheng Zhen Liang Xiaofeng Liang Wesley K. Masenten 《International Journal of Circuit Theory and Applications》2015,43(6):806-821
In this work, a power‐area‐efficient, 3‐band, 2‐RX MIMO, and TD‐LTE (backward compatible with the HSPA+, HSUPA, HSDPA, and TD‐SCDMA) CMOS receiver is presented and implemented in 0.13‐μm CMOS technology. The continuous‐time delta‐sigma A/D converters (CT ?Σ ADCs) are directly coupled to the outputs of the transimpedance amplifiers, eliminating the need of analog anti‐aliasing filters between RX front‐end and ADCs in conventional structures. The strong adjacent channel interference without low‐pass filter attenuation is handled by proper gain control. A low‐power small‐area solution for excess loop delay compensation is implemented in the CT ?Σ ADC. At 20 MHz bandwidth, the CT ?Σ ADC achieves 66 dB dynamic range and 3.5 dB RX chip noise figure is measured. A maximum of 2.4 dB signal‐to‐noise ratio degradation is measured in all the adjacent channel selectivity (ACS) and blocking tests, demonstrating the effectiveness of the strategy against the low‐pass filter removal from the conventional architecture. The receiver dissipates a maximum of 171 mW at 2‐RX MIMO mode. To our best knowledge, it is the first research paper on the design of fully integrated commercial TD‐LTE receiver. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献