Simulation analysis of a high efficiency GaInP/Si multijunction solar cell

The solar power conversion efficiency of a gallium indium phosphide(GaInP)/silicon(Si)tandem solar cell has been investigated by means of a physical device simulator considering both mechanically stacked and monolithic structures.In particular,to interconnect the bottom and top sub-cells of the monolithic tandem,a gallium arsenide(GaAs)-based tunnel-junction,i.e.GaAs(n+)/GaAs(p+),which assures a low electrical resistance and an optically low-loss connection,has been considered.The J–V characteristics of the single junction cells,monolithic tandem,and mechanically stacked structure have been calculated extracting the main photovoltaic parameters.An analysis of the tunnel-junction behaviour has been also developed.The mechanically stacked cell achieves an efficiency of 24.27%whereas the monolithic tandem reaches an efficiency of 31.11%under AM1.5 spectral conditions.External quantum efficiency simulations have evaluated the useful wavelength range.The results and discussion could be helpful in designing high efficiency monolithic multijunction GaInP/Si solar cells involving a thin GaAs(n+)/GaAs(p+)tunnel junction.

Analysis of the Impact of Off-farm Employment of Agricultural Labor on Grain Production in Shandong Province and Henan Province

[Objective] This study aimed to investigate the impact of off-farm employment of agricultural labor on grain production. [Method] Impact of off-farm employment of agricultural labor on grain production was investigated based on path analysis by using data from 200 counties and cities in Shandong Province and Henan Province in 2000 and 2008. [Result] Off-farm employment of agricultural labor affects grain production through agricultural land use patterns, off-farm employment of agricultural labor has negative impacts on grain production through multiple cropping index and positive impacts through the proportion of grain planting area. The positive impacts were greater in 2008. [Conclusion] Prerequisite of the positive impacts of off-farm employment on grain production is the substitution of agricultural mechanization development and agricultural technology advancement for agricultural labor. Orderly land circulation and scale land use should be promoted to avoid the lack of agricultural labor due to off-farm employment.

A method for prediction of unstable deformation in hot forging process by simulation

A method is proposed for prediction of the unstable deformation in hot forging process using both the determined thermomechnical parameter windows of the unstable deformation zones and finite element simulation. Taking Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy as the testing material, the thermomechnical parameter windows of the unstable deformation zones for the Ti-alloy are integrated into a commercial finite element simulation software platform. The distribution and variation of the unstable deformation zones of the alloy in hot compression process are simulated and predicted using the tailor-made finite element codes in the finite element platform. The simulation results tally with the physical experiments and the proposed method for simulation and prediction of the unstable deformation is thus verified and its efficiency is validated.

Single-event response of the SiGe HBT in TCAD simulations and laser microbeam experiment

In this paper the single-event responses of the silicon germanium heterojunction bipolar transistors(SiGe HBTs) are investigated by TCAD simulations and laser microbeam experiment. A three-dimensional(3D) simulation model is established, the single event effect(SEE) simulation is further carried out on the basis of Si Ge HBT devices, and then, together with the laser microbeam test, the charge collection behaviors are analyzed, including the single event transient(SET) induced transient terminal currents, and the sensitive area of SEE charge collection. The simulations and experimental results are discussed in detail and it is demonstrated that the nature of the current transient is controlled by the behaviors of the collector–substrate(C/S) junction and charge collection by sensitive electrodes, thereby giving out the sensitive area and electrode of SiGe HBT in SEE.

Optical simulation of CsPbI_(3)/TOPCon tandem solar cells with advanced light management

Monolithic perovskite/Si tandem solar cells(TSCs)have experienced rapid development in recent years,demonstrating its potential to exceed the Shockley-Queisser limit of single junction Si solar cells.Unlike typical organic-inorganic hybrid perovskite/silicon heterojunction TSCs,here we propose CsPbI_(3)/TOPCon TSC,which is a promising architecture in consideration of its pleasurable thermal stability and good compatibility with current PERC production lines.The optical performance of CsPbI_(3)/TOPCon TSCs is simulated by the combination of ray-tracing method and transfer matrix method.The light management of the CsPbI_(3)/TOPCon TSC begins with the optimization of the surface texture on Si subcell,indicating that a bifacial inverted pyramid with a small bottom angle of rear-side enables a further minimization of the optical losses.Current matching between the subcells,as well as the parasitic absorption loss from the front transparent conductive oxide,is analyzed and discussed in detail.Finally,an optimized configuration of CsPbI_(3)/TOPCon TSC with a31.78%power conversion efficiency is proposed.This work provides a practical guidance for approaching high-efficiency perovskite/Si TSCs.

WAVELET-BASED ANALYSIS OF CEREBROVASCULAR DYNAMICS IN NEWBORN RATS WITH INTRACRANIAL HEMORRHAGES

Intracranial hemorrhage(I)is a major problem of neonatal intensive care.The incidence of Iistypically asymptomatic and'canmot be effectively detected by standard diagnostic methods.The mechanisms underlying IH are unknown but there is evidence that stress-induced disorders inadrenergic regulation of cerebral venous blood flow (CVBF) are among the main reasons.Quantitative and qualitative:could significantly advance understanding ofthe nature of I in newbornslth1sions of CVBF in newborn rats withan experimental model of stinjection.Our analysis is bas ed on theDoppler optical coheavelet-based approachthat provides sensitiv external factors.Theobtained resultsccompanied by asupprectivity to adrenaline.Weintroducd show that the values0<1.23 estimated ithelodinto the sympathicusindicate abnormal reactions associated with the developent of I.We conclude that t he revealed areactivity of the cerebral veins to adrenaline represents a possible mechanism responsible forpat hological changes in CVBF.

Simulation of Nano Si and Al Wires Growth on Si(100) Surface

Growth of nano Si and Al wires on the Si(100) surfaces is investigated by computer simulation, including the anisotropic diffusion and the anisotropic sticking. The diffusion rates along and across the substrate dimer rows are different, so are the sticking probabilities of an adatom, at the end sites of existing islands or the side sites. Both one\|dimensional wires of Si and Al are perpendicular to the dimer rows of the substrate, though the diffusion of Si adatoms is contrary to that of Al adatoms, i.e. Si adatoms diffuse faster along the dimer rows while Al adatoms faster across the dimer rows. The simulation results also show that the shape anisotropy of islands is due to the sticking anisotropy rather than the diffusion anisotropy, which is in agreement with the experiments.

Identification of distant co-evolving residues in antigen 85C from Mycobacterium tuberculosis using statistical coupling analysis of the esterase family proteins

A fundamental goal in cellular signaling is to understand allosteric communication, the process by which sig-nals originating at one site in a protein propagate reliably to affect distant functional sites. The general principles of protein structure that underlie this process remain unknown. Statistical coupling analysis （SCA） is a statistical technique that uses evolutionary data of a protein family to measure correlation between distant functional sites and suggests allosteric communication. In proteins, very distant and small interactions between collections of amino acids provide the communication which can be important for signaling process. In this paper, we present the SCA of protein alignment of the esterase family （pfam ID： PF00756） containing the sequence of antigen 85C secreted by Mycobacterium tuberculosis to identify a subset of interacting residues. Clustering analysis of the pairwise correlation highlighted seven important residue positions in the esterase family alignments. These resi-dues were then mapped on the crystal structure of antigen 85C （PDB ID： 1DQZ）. The mapping revealed corre-lation between 3 distant residues （Asp38, Leu123 and Met125） and suggests allosteric communication between them. This information can be used for a new drug against this fatal disease.

Molecular Simulation study of Alkyl Monolayers on Si(III) Surface

The structure of eight-carbon monolayers on the H-terminated Si(III) surface was investigated by molecular simulation method. The best substitution percent 50% for octene or octyne-derived monolayer can be obtained using molecular mechanics calculation. And the densely packed, well-ordered monolayer on Si(III) surface can be shown through energy minimization in the suitable-size simulation cell.

Computer simulation on primary α-phase of Al-7%Si solidification structure

Finite difference method was used to calculate the macroscopic transportation phenomena(including temperature and concentration fields) of Al 7%Si(mass fraction) alloy. On the basis of the results,coupled with local area magnification, the nucleation and growth of primary α phase of Al 7%Si were simulated. Relating the growth process of α phase of Al 7%Si alloy in space with structures of a sample section, the morphology and precipitating process of primary α phase of Al 7%Si alloy was simulated. The results are in good agreement with those obtained experimentally.

ArcGIS^TMand Principal Component Analysis of Probe Data to Micro-Map Minerals in Round Top Rare Earth Deposit

Rare earth elements (REEs), especially heavy rare earth elements (HREEs), are in demand for their current and emerging applications in advanced technologies. Here we perform computer-driven micro-mapping at the millimeter scale of the minerals that comprise Round Top Mountain, in west Texas, USA. This large rhyolite deposit is enriched in HREEs and such other critical elements as Li, Be, and U. Electron probe microanalysis of 2 × 2 mm areas of thin sections of the rhyolite produced individual maps of 16 elements. These were superimposed to generate a 16-element composition at each pixel. Principal components analysis of elements at each pixel identified the specific mineral at that site. The pixels were then relabeled as the appropriate minerals, thereby producing a single mineral map. The overall mineral composition of the 7 studied samples compared favorably with prior analyses of the Round Top deposit available in the literature. Likewise the range of porosity in the maps was consistent with that of previous direct measurements by water saturation. This new statistical and GIS-based technique provides a robust and unbiased approach to electron microprobe mapping. The study further showed that the high-value yttrofluorite grains exhibited little tendency to cluster with other late-stage trace minerals and that the samples extended the previously documented overall homogeneity of the deposit at field scale to this microscopic scale.

Simulation for microstructure evolution of Al-Si alloys in solidification process

The numerical simulation for microstructure evolution of Al-Si alloy in solidification process is carried out with phase field model. The phase field model, solution algorithm and the program of dendrite growth are introduced. The definition of initial condition, boundary condition and the stability condition of differential format are all included. The simulation results show that the evolution of dendrite morphology is as follows: the initial circle nucleus transforms to the rectangle one firstly, then its corners develop to the four trunks and from which the secondary side branches are generated and even the third side branches are produced from secondary ones. The dendrite tip radius decreases quickly at the initial stage and changes slowly at the late stage, which is mainly due to the fact that more and more side branches appear and grow up. The comparisons of dendrite morphology between simulated results and investigations by others are also presented. It is proved that the dendrite morphologies are similar in trunks and arms growth, so the developed phase field program is accurate.

Numerical simulation of thermal-mechanical process of Al-Si-Pb alloy treated by high current pulsed electron beam

The modified microstructure of Al-Si-Pb alloys irradiated by high current electron beam (HCPEB) reveals three distinct regions: a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.

基于SIS模型的网络群体性事件传播及防控研究

[目的/意义]网络群体性事件爆发性强,社会影响大,是近年来众多学者关注的焦点。研究网络群体性事件的传播规律,对政府进一步完善网络治理有一定的理论价值及现实意义。[方法/过程]利用SIS传染病模型中的动力学原理,综合考虑社会环境和各种影响因素,构建网络群体性事件传播的数学模型。模型可转化为一个可分离变量的微分方程,利MATLAB求解出网络群体性事件参与人数的变化轨迹。[结果/结论]模型表明,在促进函数和阻止函数的作用下,网络群体性事件的参与者和未参与者可以相互转换;根据网络群体性事件爆发前、爆发时、爆发后模型的仿真研究结果,认为在事件传播过程中存在着阈值;政府及相关职能部门可以参照阈值采取不同干预措施,有效控制网络群体性事件的发展。

基于熵权TOPSIS法的房地产业对新型城镇化通径分析——以海南省五指山市为例

以21世纪以来特别是"十二五"时期新型城镇化与房地产相关数据为样本,运用改进的熵权TOPSIS法对新型城镇化质量综合测度,采用通径分析法研究五指山市房地产各指标对新型城镇化的影响作用程度。结果表明:2009—2014年五指山的新型城镇化质量综合水平呈现稳步上升状态,始终处于中级与良好状态;2014年新型城镇化各指标发展程度由小到大依次为人口城镇化、土地城镇化、经济城镇化、生活城镇化和社会城镇化,人口与土地始终是制约五指山新型城镇化快速发展的关键因素;商品房销售均价、房地产开发投资额、经济适用房总计划投资额与新型城镇化呈正相关,对新型城镇化的影响作用依次减小,新开工房屋面积与新型城镇化质量呈负相关,但影响作用程度较微弱。

电厂SIS与仿真机连接及其数据的仿真应用

介绍了电厂监控信息系统(SIS)与仿真机的连接及SIS数据的仿真应用。SIS和电站仿真相结合对电厂的安全、经济运行有着重要的意义。在应用中设计了SIS与电站仿真系统之间的连接方式,开发了相应的接口软件,并把SIS数据与仿真机应用相结合。经过多个电厂的实际应用,证明SIS环境下仿真系统不仅能够更快、更逼真地实现仿真机的开发,同时也为培训人员进行现场事故分析和故障重演等提供了很好的应用手段。

基于虚拟DCS与SIS的数据比较系统的开发

以虚拟分散控制系统(DCS)仿真控制技术和系统的相似度理论为基础,利用监控信息系统(SIS)和仿真系统的互联条件,开发了用于大型发电厂真实数据和仿真数据的比较系统。采用系统的相似度理论实现了相似度的算法,利用实时和关系数据库技术对数据进行管理和计算,同时运用ADO(activeX data object)接口技术方便地实现了数据库和应用程序的数据连接。

无标度网络中的SIS模型的计算机模拟

经研究,现实的人际网络与无标度网络是很相似的,而传统的SIS模型是建立在均匀网络上的,已经不能满足现在情况.由于无标度网络的复杂性,建立新的模型是非常困难的,所以本文利用计算机模拟的方式来研究无标度网络中的SIS模型.得到了在无标度网络下,传染病传播是很容易的结论.

电站虚拟仿真系统与SIS数据集成及应用研究

以600MW燃煤机组、Foxboro的I/ADCS系统和GE的XDPSDEH系统为研究对象,采用图形化建模和虚拟DCS技术,开发了基于Web平台的电站虚拟仿真系统,并通过虚拟仿真系统与SIS数据集成,建立虚拟仿真系统的初始工况,为全工况运行分析提供起始运算点。介绍了虚拟仿真系统的设计思想、体系结构以及开发过程,阐述了虚拟仿真系统与SIS数据集成的具体过程及应用。