Chaff Jamming Recognition of Radar

A modified chaff jamming recognition method of radar is investigated using grey relational analysis (GRA) based on the difference in echo correlation characteristics between a complex rigid target and chaff cloud in time domain.Slice method (SM),a novel modeling approach,is proposed to construct an electromagnetic scattering model of chaff cloud in a scenario with slowly moving platform that is targeted.The diffusion characteristics and echo characteristics of the chaff cloud are analyzed.The GRA of a real target and chaff cloud shows that the adjacent return waves have a good correlation for the target but a weak correlation for chaff cloud.Since the correlation degree of chaff cloud's echo is far lower than that of a complex rigid target's,the chaff jamming can be identified by setting a reasonable threshold.Simulation results are presented to verify the effectiveness of this method.     

基于空间曲线啮合轮的同平面多轴输出微小减速器研究进展

微小减速器是微小机械系统的重要组成部分,是目前重要研究领域之一。介绍了基于空间曲线啮合轮传动机构而设计的同平面多轴输出微小减速器,包括不同特点的两种结构形式,即基于正多边形轴分布的串联式多轴输出微小减速器和并联式多轴输出微小减速器,并例举了应用实例。最后,归纳了其工业化应用需研究的主要方向。     

Influence of poly(n‐octadecyl acrylate) on mechanical properties,melting behavior,and morphology of polypropylene/aluminum trihydroxide composites

Poly(n‐octadecyl acrylate) (PnOA) was used as an interfacial compatibilizer for improving the performance of polypropylene/alumina trihydrate (PP/ATH) composites in this study. The influences of PnOA on the properties of fire‐retardant PP/ATH composites were evaluated by tensile and impact tests, differential scanning calorimetry (DSC), scanning electron microscope (SEM) observation, thermogravimetric analysis, and mass flow rate tests. The results suggested that PnOA significantly improved the mechanical properties and rheological behavior of the PP/ATH composites. SEM observation helped formulate reasons for these differences. A pronounced difference in DSC curves was detected for the composites with and without PnOA when the temperature is near the melt temperature of PnOA. Tentative theoretical explanation was also provided based on related DSC and SEM analysis. PnOA is a promising new compatibilizer for polyolefin composites with aluminum trihydrate as a flame retardant. Copyright © 2011 John Wiley & Sons, Ltd.     

Superior reinforcement in polyamide 1010/multiwalled carbon nanotube composites realized by high‐rate drawing and incorporation of compatibilizer

To realize the full potential of carbon nanotubes (CNTs) in polymer/CNT nanocomposites, many complicated chemical treatments have been developed to modify the CNTs. Nevertheless, the reinforcing efficiency is still not satisfactory in most cases. In this study, a dramatically improved mechanical enhancement is obtained for polyamide 1010/multiwalled carbon nanotube (MWNT) composites simply by exerting high‐rate drawing and incorporating a commercially available compatibilizer. For the fibers prepared at high draw ratio, their tensile strength and modulus are improved by 137 and 132%, respectively, through adding only 0.5 wt% MWNTs. In particular, the increase in strength is at a very high level for the case of non‐covalent interaction since CNTs could be stretched to failure according to theoretical calculation. It is demonstrated that this reinforcement is mainly attributed to the compatibilizer inducing good dispersion, and the high‐rate drawing inducing strong interfacial interaction and orientation of MWNTs. Copyright © 2012 Society of Chemical Industry     

Investigation of the copper concentration on photocurrent collection of CuInSe2 solar cells

In this study, CuInSe₂ (CISe) thin films were prepared from thermally evaporated Cu/In precursors, having various Cu/In atomic ratio, under the same selenization conditions. The precursors were converted into CISe absorber by annealing in a quartz tube furnace in the selenium vapours at substrate temperature of 500 °C. We developed four CISe films with Cu/In atomic ratio of 0.81–1.19, denoted as Cu‐very rich, Cu‐rich, Cu‐poor, and Cu‐very poor CISe thin films respectively. The effects of Cu/In atomic ratio on grain size, surface morphology, micro‐structure and defect formation of the resulting CISe films were examined. It has been found that the photovoltaic properties were strongly related to Cu concentration, as well as carrier transport mechanism. Defects at the surface and in the bulk of CISe thin films were observed using X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy, Raman spectroscopy, energy dispersive X‐ray spectroscopy and scanning electron microscopy. Moreover, XRD revealed that the CISe film surface had a preferred orientation along the (112) plane. The XRD intensity and full width at half maximum of the (112) plane of CISe varied according to the Cu/In atomic ratio. Our experimental results show that the Cu‐rich solar cell achieves conversion efficiency of 4.55% and exhibits an exceptional high short‐circuit current density. Copyright © 2016 John Wiley & Sons, Ltd.     

On the performance of a class‐4 partial response digital communication system

Abstract

The dark conductivity of phosphorus‐doped amorphous‐silicon alloys (a‐Si:H:F) prepared by the RF plasma decomposition of a gaseous mixture of SiF₄, H₂ and diluted PH₃ is extremely high; it exceeds 10 (O‐cm)^‐1 with only a small amount of PH₃ (～500 ppm) added in the gas phase. These doping characteristics represent a significant improvement over the doping characteristics of a‐Si:H alloys prepared by a glow‐discharge of SiH₄. The improvement was found to be due to the fact that P‐doped a‐Si:H:F contains microcrystallites which are embedded in an amorphous network. The percolation process in these two‐phase systems gives rise to high conductivity. We have used transmission electron microscopy (TEM) and diffraction (TED) to determine the critical surface fraction, ρ_c, of crystallinity at the onset of extended conduction. The measured ρ_c is approximately 0.46. This percolation limit provides a basis for the analysis of the electrical properties of P‐doped a‐Si:H:F.     

计算机节能监视系统的设计与实现

计算机节能是节能减排的一项举措,通过编制程序来获取目的计算机的活动性,有效的掌握计算机开机情况。     

A Galerkin isoparametric finite element analysis of acoustic field in lined ducts

Abstract

A Galerkin based finite element method is used to solve acoustic pressure distribution in unlined or lined ducts of arbitrary profile with circular cross section. For isoparametric elements with cubic polynomials as shape functions, two elements per wavelength is proved necessary to keep solution error within 2.5%. Several examples are solved to show the capability of the derived technique, and the results, are good.     

ZTE Communications Call for Papers Special Issue on Using Artificial Intelligence in Internet of Things

Internet of Things has received much attention over the past de-cade.With the rapid increase in the use of smart devices,we arenow able to collect big data on a daily basis.The data we are gather-ing and related problems are becoming more complex and uncer-tain.Researchers have therefore turned to AI as an efficient way ofdealing with the problems created by big data.This special issue of ZTE