江西铜业集团公司会议电视系统建设方案初探

本文从会议电视系统的概况出发 ,分析了基于多种网络环境会议电视系统的特点 ,提出了江西铜业集团公司会议电视系统的建设方案及实现方法     

离散坐标SN方法在中子测井数值模拟中的应用

本文介绍离散坐标 S_N 方法在测井数值模拟中的应用,计算时应用程序 DOT3.5。本文中能区划分为四群,采用 S_4、P_1散射近似,群常数由少群群常数计算程序 FSMP/D 产生。对江汉石油测井研究所的石灰岩、砂岩、白云岩三种岩性、不同孔隙度的模型井群进行了计算,并作出了理论岩性校正图版。与实验岩性校正图版相比,二者符合良好。     

新型填料结构旋转床流体力学特性

以空气-水为工作介质,研究了填料特性、超重力因子、气体流景和液体流量等对不同填料结构旋转床床层压降特性的影响.实验结果表明,离心压降、干床压降、湿床压降与填料的材质、板间距、空隙率等密切相关;床层压降随超重力因子、气体流量的增加而增大,与液体流量几乎无关;在相近的操作条件下,床层压降与文献报道丝网错流旋转床的相近,为逆流床的十分之一;运用最小二乘法对实验数据回归得出了干湿床压降的关联式,计算的干湿床压降与实验值的平均误差小于15%.     

Synthesis and properties of homogeneously dispersed polyamide 6/MWNTs nanocomposites via simultaneous in situ anionic ring‐opening polymerization and compatibilization

Toluene 2, 4‐diisocyanate (TDI) functionalized multiwalled carbon nanotubes (MWNTs‐NCO) were used to prepare monomer casting polyamide 6 (MCPA6)/MWNTs nanocomposites via in situ anionic ring‐opening polymerization (AROP). Isocyanate groups of MWNTs‐NCO could serve as AROP activators of ?‐caprolactam (CL) in the in situ polymerization. Fourier transform infrared (FTIR) showed that a graft copolymer of PA6 and MWNTs was formed in the in situ polymerization. MWNTs‐PA6 covalent bonds of the graft copolymer constituted a strong type of interfacial interaction in the nanocomposites and increased the compatibility of MWNTs and MCPA6 matrix. The nanocomposites were characterized for the morphology, mechanical, crystallization, and thermal properties through field emission transmission electron microscopy (FETEM), tensile testing, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). FETEM analysis showed that MWNTs were homogeneously dispersed in MCPA6 matrix. The initial tensile strengths and tensile modulus of the nanocomposite with 1.5 wt % loading of MWNTs were enhanced by about 16 and 13%, respectively, compared with the corresponding values for neat MCPA6. DSC analysis indicated that the crystallization temperature of the nanocomposites was increased by 8°C by adding 1.5 wt % MWNTs compared with pure MCPA6. Besides, it was found that the thermal stability of MCPA6 was improved by the addition of the MWNTs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Cracking in poly(trimethylene terephthalate) spherulites

The crack behavior of poly(trimethylene terephthalate) spherulites was studied mainly by polarizing optical microscopy, along with scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition to the effects of temperature and constraining substrate, another important factor, film thickness, on the formation of crack was first put forward and investigated. The emergence of the first crack occurred at 120°C during cooling after crystallization at 190°C for the sample with a thickness of 31.0 μm. For the spherulites growing between glass sheets, it was interesting that the sample with a thickness of 26.0 μm exhibited the largest number of cracks measured per 200 μm of radius, whereas samples thicker than 100 μm or thinner than 1 μm did not induce the formation of crack. Also, spherulites growing between two polyimide and two Teflon sheets showed no crack. Glass sheets lubricated with silicon oil restrained the number of cracks but did not eliminate cracks. SEM revealed that the cracking was about 900 nm in width. In addition, the AFM results suggest that the cracks had a depth of at least 150 nm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

On clutter dof for phased array airborne early warning radars

In recent years, considerable attention has been paid to adaptive clutter suppression for airborne early warning (AEW) radars. A necessary condition for efficient clutter suppression is that the number of adaptive degrees of freedom (DOF) is no less than that of clutter DOF. This paper analyzes the DOF of clutter for phased array AEW radars. The new results obtained here are helpful to design and adaptive system for clutter suppression.     

Pb(Mg1/3Nb2/3)O3-PbTiO3晶体组分对结构与性能的影响

用熔体Modified Brdgman法生长出尺寸直径40 mm长度80 mm的弛豫铁电单晶PMNT90/10,表明该方法不仅适合在准同型相界(MPB)附近生长PMNT单晶,也适合生长PT含量很低的PMNT单晶.在生长出的PMNT90/10晶体中,铁电相与顺电相两相共存,并呈现亚微畴结构特征.随着晶体组分由PMN组元变化到MPB组分附近,PMNT的电畴结构呈现微畴-亚微畴-不规则宏畴-规则宏畴演化系列,而介电弛豫特性则逐步弱化.PMNT固熔体的电学性能依赖于晶体组分,(001)切型PMNT90/10晶体的压电常数d33约80 pC/N,显著低于MPB附近组分,但其介电常数ε达到12600,明显高于后者.     

一种小快拍情况下的稳健的波束形成方法

小快拍情况下采样协方差矩阵没有收敛,假设的白噪声表现为色噪声,从而导致了自适应波束形成畸变.本文从采样协方差矩阵特征值分析出发,提出了一种自适应对其修正的方法,相当于对采样协方差矩阵进行扰动,改善了采样协方差矩阵的收敛性,从而提高了波束形成的性能和稳健性.最后性能分析和计算机仿真验证了所提方法的有效性和优越性.     

Applications of high-gravity technologies in gas purifications: A review

The traditional gas purification techniques such as wet gas desulfurization, with their advantages of large-scale implementation and maturity, have still been widely used. However, the main drawback of these techniques is the low transfer efficiency, which normally needs towers as tall as tens of meters to remove the pollutants. Therefore, new technologies which could enhance the mass transfer efficiency and are less energy-intensive are highly desirable. As a process intensification technology, high-gravity technology, which is carried out in a rotating packed bed(RPB), has recently demonstrated great potential for industrial applications due to its high mass transfer efficiency, energy-saving, and smaller volume. This consequently provides higher efficiency in toxic gas removal, and can significantly reduce the investment and operation costs. In this review, the mechanism,characteristics, recent developments, and the industry applications of high-gravity technologies in gas purifications, such as hydrogen sulfide, nitrogen oxide, carbon dioxide, sulfur dioxide, volatile organic compounds and nanoparticle removal are discussed, most of the demonstration projects and practical application examples in gas purification come from China. The perspective and prospective of this technology in gas purification and other fields are also briefly discussed.     

基于Hilbert信号空间的未知干扰自适应识别方法

针对大样本下未知干扰类型的分类识别问题,该文提出一种基于信号特征空间的未知干扰自适应识别方法。首先,基于Hilbert信号空间理论对干扰信号进行处理,建立干扰信号特征空间,进而利用投影定理对未知干扰进行最佳逼近,提出基于信号特征空间的概率神经网络(PNN)分类算法,并设计了未知干扰分类识别器的处理流程。仿真结果表明,与两种传统方法相比,该方法在已知干扰的分类精度方面分别提高了12.2%和2.8%;满足条件的未知干扰最佳逼近效果随功率强度呈线性变化,设计的分类识别器在满足最佳逼近的各类干扰中总体识别率达到91.27%,处理干扰识别的速度明显改善;在信噪比达到4 dB时,对未知干扰识别准确率达到92%以上。