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1.
根据无人作战模拟研究、开发过程中分队级作战单位建模与仿真环节上所存在的VV&A问题,从军事建模的过程与军事工程技术的角度出发,将一般仿真过程中的VV&A技术与军事作战模拟的特点以及无人作战模拟的特殊性三者有机的结合在一起,深入的探讨了在无人作战模拟仿真过程中VV&A问题的解决办法以及实现过程。通过对无人作战模拟仿真中VV&A的研究与解决,为今后的作战模拟,特别是无人作战模拟中如何解决建模及仿真过程中所存在的类似问题提出了一套系统的、科学的实现办法,具有一定的理论及实践意义。对于我军无人作战研究的深入开展以及跨越式发展具有一定的参考价值。  相似文献   

2.
Modulation of absorption of middle-infrared radiation in double tunneling-coupled quantum wells in longitudinal electric fields is studied. A specific feature of the quantum wells is the small separation in energy between the two lower levels. As a consequence, the levels may exhibit “anticrossing” even in low transverse electric fields. An interpretation of the change in intersubband absorption is suggested. The interpretation is based on the assumption that a transverse electric-field component may appear in the structure. The change in the absorption coefficient is calculated taking into account the redistribution of electrons between size-quantization subbands and the changes in the temperature of electrons in the subbands in the longitudinal electric field, as well as the changes in the optical matrix elements, the energies of transitions, and the concentrations of electrons in the subbands in the transverse electric field. The possibility of using the structure for the efficient modulation of middle-infrared light with the photon energy 136 meV is shown.  相似文献   

3.
An attempt is made to determine if investment in R&D and the hiring of college-educated employees result in a higher rate of inventions. The relationship between the input of R&D and inventive output is studied in two samples of Japanese factories, 34 in 1982 and 44 in 1970. These results are compared with findings in a parallel American study. The correlations between R&D and inventive output are similar in Japan and America in the 1980s, despite some differences in the management of innovation in the two nations. Moreover, the most Westernized subsample of Japanese firms in the 1970s had correlations between R&D and invention similar to those observed in the American study. Thus, it is concluded that some degree of convergence may be taking place in R&D management strategies in the two nations  相似文献   

4.
Changes in biosynthesis of cholesterol and free fatty acids from 2-14C-acetate in the host liver and tumour tissue as well as concentrations of various classes of lipids in blood were determined in rats bearing the transplanted Pliss lymphosarcoma. The transplantation of the tumour stimulates cholesterol biosynthesis de novo in the liver, but produces no changes in the fatty acid synthesis. Tumour growth is accompanied by a progressive increase in the content of triglycerides and beta-lipoproteins with a parallel drop in the alpha-cholesterol level in the animal blood. The concentration of total cholesterol is of phasic character depending on the stage of tumour growth. The possible mechanisms determining such alterations in lipids metabolism are discussed.  相似文献   

5.
Special features of metal-organic chemical vapor deposition of AlGaN epitaxial layers and AlGaN/GaN superlattices either in an Epiquip VP-50 RP research and development reactor (for a single wafer 2 in. in diameter) or in an AIX2000HT production-scale reactor (for up to six wafers 2 in. in diameter) are stud-ied. It is found that the dependence of the aluminum content in the solid phase on the trimethylaluminum (TMA) flux in a reactor levels off; this effect hinders the growth of the layers with a high aluminum content in both types of reactors and is more pronounced in the larger reactor (AIX2000HT). Presumably, this effect is a consequence of spurious reactions in the vapor phase and depends on the partial pressure of TMA in the reactor. The aluminum content in the layers can be increased not only by reducing the total pressure in the reactor but also by increasing the total gas flow through the reactor and reducing the trimethylgallium flux. The approaches described above were used to grow layers with a mole fraction of AlN as large as 20% in the AIX2000HT production-scale reactor at a pressure of 400 mbar (this fraction was as large as 40% at 200 mbar). AlGaN layers with the entire range of composition were grown in the Epiquip VP-50 RP reactor.  相似文献   

6.
微视频在学校各类教育中应用越来越普遍.依据微视频的教学特点,针对高校计算机操作性课程中存在的问题,本研究依据ADDIE模型和ARCS动机理论,探索构建微视频在高校计算机操作性课程中的教学应用模型,通过教学案例展示微视频在课堂应用中教与学的过程,利用微视频提高课堂教学质量.  相似文献   

7.
Using the spectral domain technique, changes in the characteristics of electromagnetically coupled stacked rectangular patch antennas due to variations in the alignment of patches and patch sizes are investigated. Some of the observations can be used in the design of these antennas in order to equalize the input impedances at the resonances, shift the resonant frequencies, broaden the bandwidth, and estimate changes in the radiation patterns. It is specifically shown that a displacement in the top patch in the direction of resonance can broaden the beamwidth in the E-plane at the upper resonance at the expense of some distortion in the radiation pattern  相似文献   

8.
Regulatory reform has changed the organization of the broadcasting industry in Brazil and Argentina in the past decade. Although responding to a similar set of pressure, the pace, instruments, and character of reforms have been different in the 2 countries, resulting in media markets of diverse natures. This study argues that these different policy outcomes in the reform of broadcasting regulation in Brazil and Argentina reflect variations in three factors: the nature of the political system, the structure of the existing broadcasting industry, and the ideological legacy in the regulation of communication industries. The case of regulatory reform in the broadcasting industry illustrates different policy patterns in the restructuring of state-industry relations in communications and information technology industries in the 2 neighboring countries.  相似文献   

9.
The primary results of the study of hemoglobin and ferritin in erythrocytes in leukemia are considered in the light of the M?ssbauer spectroscopy data. The quantitative changes in hemoglobin and ferritin during differentiation of cells in the Friend erythroleukemia are shown. The qualitative changes in iron electronic structure of oxyhemoglobin in different forms of human leukemias are shown.  相似文献   

10.
《Microelectronics Reliability》2014,54(6-7):1119-1124
O vacancy formation and the associated electronic defect states in Hf-based oxides have been investigated over a wide range of compositions using first-principles hybrid density functional calculations. Based on the generated structure models, we have identified the most probable O coordination structures in amorphous HfO2 and in Hf-silicates, respectively. Our calculations showed that the formation energies of O vacancy and the positions of the induced defect states in the band gap are largely dependent on the local structures of the vacancy site rather than on the compositions of Hf-silicates. Considering the measured valence band offset between Si and Hf-silicates, a considerable amount of O vacancies are likely to stay in the charge neutral state in Hf-silicates when the Fermi level lies in the band gap region of Si. Furthermore, the concentration of O vacancy in Hf-silicates was found to be much lower than that in HfO2 when the Fermi level lies in/below the mid-gap region of Si. Consequently, the flat band voltage shift and the transient threshold voltage instability can be significantly reduced in Hf-silicates in comparison to that in HfO2, indicating that the presence of a Hf-silicate layer in between the gate oxides and the Si substrate could be beneficial to the performance of the CMOS device.  相似文献   

11.
在闭箱、开口箱、被动辐射体箱和带通箱系统的设计中,人们已认识到单元的TS参数和箱体的声学参数有紧密的配合关系。一旦箱体的结构设计有所确定,安装在箱体上的扬声器单元的TS参数也必须确定,这样,系统的低音频特性就因此而定。但是在批量投产时,TS参数的偏差将对系统的低音频特性产生变化。以开口箱的系统频率响应曲线为分析目标,要观察TS参数的偏差所产生的变化。为此,采用LEAP5扬声器设计软件作相应的模拟,证明只要TS参数的偏差在一定的范围内,频率响应曲线的变化也可以维持在一个偏差带内。这样,可根据系统的技术指标来确定TS参数的偏差。  相似文献   

12.
This paper presents an exact field theory treatment for the H-plane waveguide junction with three-sided ferrite prism. The treatment is general, being independent of the geometrical symmetry of the junction, the number of ports, and the location of the ferrite post inside the junction. The solution of the wave equations in the ferrite post and in the surrounding region is written in the form of an infinite summation of cylindrical modes. The fields at the ferrite-air interface are matched using the point-matching technique. This results in two amplitudes for the cylindrical modes describing the fields in the air region in the form of a matrix. The fields at the arbitrary boundary between the air region and the waveguides are also matched using the point-matching technique. This results in a finite system of nonhomogeneous equations in the field amplitudes. The three-port waveguide junction circulator with central triangular ferrite post is analyzed using this technique. Two specific arrangements are considered. In the first arrangement, the points of the triangles are in the centers of the waveguides, and in the second, the sides of the triangles are in the centers of the waveguides. The method used in this paper can also be applied to study the effect of the ferrite-post geometry on the circulator performance in order to seek the best possible circulator structure. Excellent agreement has been found between published experimental measurements and the numerical results obtained by this technique in the case of a waveguide junction circulator with cylindrical ferrite post.  相似文献   

13.
吴迪  王瑞 《电波科学学报》2019,34(5):655-662
利用2007-2013年的COSMIC掩星数据,分析了E区与F区电离层闪烁的变化特征.发现用闪烁出现频次、闪烁发生率以及闪烁强度来表征的电离层闪烁出现规律比较相似.E区电离层闪烁在夏季半球的中纬地区最强,其次是春秋季的低纬地区和冬季半球.就经度分布来说,春秋季E区电离层闪烁呈四波结构.对F区电离层闪烁来说:南美-大西洋扇区在12月至点最为显著;非洲和太平洋扇区在6月至点最为显著;大西洋扇区在春秋分季最为显著.极区也出现中等强度的闪烁,尤其在南半球的90°E~180°E扇区较为显著.高纬E区电离层闪烁强度随太阳活动的增强而增强,而低纬和南半球的中纬E区闪烁随太阳活动的增强而减弱.高纬和低纬F区闪烁随太阳活动的增强而增强,而中纬F区电离层闪烁对太阳活动无显著依赖关系.对于赤道区来说,北半球60°W~60°E经度区闪烁强度随太阳活动的变化最为显著,其次是南半球60°E~210°E附近;而对于高纬地区来说,F区闪烁强度随太阳活动的变化最为显著的区域在南半球60°E~210°E附近.  相似文献   

14.
氧含量对VO2-x晶格特性和结构相变影响的研究   总被引:2,自引:1,他引:1       下载免费PDF全文
采用沉淀法制备了氧含量不同的VO2-x纳米粉.对样品进行了差式扫描量热(DSC)、X-射线衍射(XRD)和透射电子显微镜(TEM)的测试,并结合第一性原理的计算结果,具体分析了氧含量对氧化钒纳米粉的晶格特性和结构相变造成的影响:缺氧样品中形成钒填隙,富氧样品中形成氧填隙,两种缺陷分别造成晶胞体积的膨胀;缺陷带来的各向异性造成晶粒形状的改变;同时,不同缺陷态造成的能带中电子状态的改变也可能成为影响氧化钒的结构相变特性的重要因素之一.  相似文献   

15.
简季  宋练  谢洪斌  罗真富  谭德军  高波 《红外》2013,34(8):30-34
矿山开采中产生的固体废弃物和废液会使矿区土壤中富集重金属元素,进而影响矿区内的农作物生长。选择重庆市万盛区矿区作为研究区,采集红薯和南瓜的实测高光谱数据和土壤样本的重金属含量数据。通过对土壤重金属含量和农作物的红边位置偏移进行相关分析,发现不同土壤重金属含量对研究区内主要农作物的影响是不同的。可以看出,在研究区内的两种主要农作物中,红薯对矿区土壤中的重金属Cr、Mn和Cd比较敏感,而南瓜则对以上三种土壤重金属具有一定的吸收和抵抗作用。该结果可以为万盛区矿区内农作物种植的选择提供理论依据。  相似文献   

16.
One of the concerns clinicians have relates to the interpretation of noninvasive pulse oximeters in newborns since at birth high levels of fetal hemoglobin (HbF) is present in the blood. Accurate in vivo studies of pulse oximeters in infants with predominantly HbF cannot be easily performed. Therefore, the objective of this in vitro study was to determine whether the presence of high levels of HbF in the blood can significantly affect the accuracy of noninvasive pulse oximeters. It is evident from our results that there is no perceptible difference in the 650-1000 nm wavelength region, which is commonly used in pulse oximetry, between the optical absorption spectra of hemolyzed whole adult and fetal blood. Our observations are in good agreement with in vivo studies published by other investigators showing considerable correlations between SpO2 measured by a pulse oximeter and SaO2 values analyzed in vitro by an IL 282 CO-Oximeter.  相似文献   

17.
A resonator method for measuring the dielectric properties of strongly absorbing materials, which enables one to detect small variations in the permittivity, is developed. By this method, the permittivity of fresh (without anticoagulants) venous and capillary blood and its variation in the process of clotting with time is determined. The dependence of the reflection coefficient of the resonator at the resonance frequencies of the permittivity of venous blood in the course of reading of the glycaemic profile is studied, and a certain correlation between the variation in the glucose content in blood and these quantities is found. The dependence of the reflection coefficient of the resonator loaded to the human hand in the process of reading of the glycaemic profile is studied, and it is shown that the correlation between the glucose content in human blood and the reflection coefficient of the resonator is observed only in the initial section of the increase in the glucose content in blood after glucose intake.  相似文献   

18.
Improved LUT Technique for HPA Nonlinear Pre-Distortion in OFDM Systems   总被引:3,自引:0,他引:3  
In this paper, we focus on the Look-up Table (LUT) technique for the compensation of HPA nonlinear distortion. An improved LUT method is proposed with better performance compared with conventional LUT technique in terms of convergence speeds, BER and total degradation (TD). It can get over 8 dB gain in out-of-band spectrum re-growth suppression and about 0.3 dB BER performance gain than conventional LUT technique with the same iteration times. Also, we propose an actual application of HPA with pre-distorter in OFDM transmitter. Ai Bo was born in Shannxi Province in China on February 7, 1974. He received a BSc. Degree from Engineering Institute of Armed Police Force in 1997, a Master and Dr. degree from Xidian University in 2002 and 2004 in China respectively, and now working as a post dr. in Dept. of E&E, state of key lab. on microwave and digital communications in Tsinghua University in China. He has once participated in the key research project on HDTV in TEEG (Team of Engineering Expert Group) of China. He is an editorial committee member of journal of “Computer Simulations”, “Information and Electronic Engineering”, an IEEE member and a senior member of Electronics Institute of China (CIE). He has published over 60 scientific papers in his research area till now. His current interests are the research and applications of OFDM techniques with emphasis on synchronization and HPA linearization techniques. Yang Zhi-Xing graduated from Tsinghua University, P.R. China in 1970. He is now a Professor and Deputy Director of State Key Lab. on Microwave and Digital Communication at the Department of Electronic Engineering and the Director of the DTV R&D Center in Tsinghua University. As a DTV technical expert for the Chinese government, Professor Yang has also been a member of the DTV standardization Committee of China and a leader of the DTV Standardization Harmonizing Group in Ministry of Information Industry of China. His major research interests include broadband information transmission technologies and DTV broadcasting systems. Pan Chang-Yong received the B.S. and M.S. degrees from the Department of Electronic Engineering in Tsinghua University, P.R. China, in 1996 and 1999, respectively. He is now an associate professor in the Department of Electronic Engineering and a member of the DTV R&D Center in Tsinghua University. His research interests are in the areas of broadband wireless transmission systems and satellite communications. Zhang Tao-Tao was born in Shandong Province in China in 1982, he received BSc. degree from Tsinghua University in 2004 and now pursing his Master degree in Dept. of E&E, state of key lab. on microwave and digital communications in Tsinghua University in China. His research interests is the power amplifier linearization techniques. Wang Yong was born in Shannxi Province in China in 1976. He received a BSc., a Master and a Dr. Degree from Xidian University in China in 1997, 2002 and 2005, respectively, and now is an associate professor in Xidian University. He has once participated in the key research project on HDTV in TEEG (Team of Engineering Expert Group) in China and is an IEEE Member. His interests are broadband multimedia communications. Ge Jian-Hua was born in September, 1961 in JiangSu Province in China. He received the B.Sc., Master and Ph.D. degree from Xidian University in 1982, 1985 and 1989, respectively. He is now the professor in both Xidian University in Xi’an and Shanghai Jiaotong University in Shanghai. He is the senior member of Chinese Electronics Institute. He has won lots of scientific and technical prizes in China and published many papers. His interests are transmission communications and web security.  相似文献   

19.
Studies are being carried out in Italy concerning the strategy for the introduction in the 1990's of optical fiber systems in the distribution network, in order to supply customers with broad-band services (in particular with video services). This paper deals with some of the main choices that are being done, in particular in view of a field trial which is planned in Rome in 1988.  相似文献   

20.
随着时代的发展,国家对人才的需求量不断增加,并且对人才培养的要求越来越高。高校作为人才输出的重要基地,人们对高等教育的重视程度不断加深,尤其是近年来高校在发展的过程中其规模也在不断的扩展,导致固定资产管理中的一些问题逐渐凸显出来。本文就固定资产管理中存在的问题进行分析,进一步探讨云计算技术在高校固定资产管理中的应用。  相似文献   

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