Perfect Blind-Channel Shortening for Multicarrier Systems

In multicarrier systems, when the order of a channel impulse response is larger than the length of the cyclic prefix (CP), there is a significant performance degradation due to interblock interference (IBI). This paper proposes a blind-channel shortening method in which the equalizer parameter vector is formed by the noise subspace of the received signal correlation matrix so that the output power is maximized. The proposed method can not only shorten the effective channel impulse response to within the CP length but also maximize the output signal-to-interference-and-noise ratio while eliminating the IBI. We point out that the performance depends on the choice of a decision delay and propose a simple method for determining the appropriate delay. We propose both a batch algorithm and an adaptive algorithm and show by simulation that they are superior to the conventional algorithms.     

ADI-FDTD Method With Fourth Order Accuracy in Time

This letter presents an unconditionally stable alternating direction implicit finite-difference time-domain (ADI-FDTD) method with fourth order accuracy in time. Analytical proof of unconditional stability and detailed analysis of numerical dispersion are presented. Compared to second order ADI-FDTD and six-steps SS-FDTD, the fourth order ADI-FDTD generally achieves lower phase velocity error for sufficiently fine mesh. Using finer mesh gridding also reduces the phase velocity error floor, which dictates the accuracy limit due to spatial discretization errors when the time step size is reduced further.     

新型低伤害压裂液的研究与应用

针对安棚油田特低孔特低渗、储层温度高、微裂缝发育等地质特征 ,通过室内实验 ,研制出具有耐高温、低伤害、延迟交联等特点的新型压裂液体系 ,并进行了 2 0多井次的现场试验。结果表明 ,该压裂液具有很好的适应性 ,完全可满足安棚油田特低孔特低渗储层压裂改造的要求     

Investigation of Mechanical and Electrical Characteristics for Cracked Conductive Particle in Anisotropic Conductive Adhesive (ACA) Assembly

In an anisotropic conductive adhesive (ACA) assembly, the electrical conduction is usually achieved with the conductive particles between the bumps of integrated circuit (IC) and corresponding conductive tracks on the glass substrate. Fully understanding of the mechanical and electrical characteristics of ACA particles can help to optimize the assembly process and improve the reliability of ACA interconnection. Most conductive particles used in the ACA assembly are with cracks in the metal coating of the particles after the ACA bonding. This paper introduced the fracture analysis by applying the cohesive elements in the numerical model of the nickel-coated polymer particle and further simulating the cracks initiation and propagation in the nickel coating during the ACA bonding. The simulation results showed that the stress distribution on the nickel-coated particle with cracks was significantly different from that on the nickel-coated particle without crack, indicating that the stress analysis by taking the crack into consideration is very important for the reliability assessment of the ACA interconnection. The stress analysis of cohesive elements indicated that the cracks initiated at the central area of the nickel coating and propagated to the polar area. Furthermore, by the introduction of a new parameter of the virtual resistance, a mathematical model was established to describe the electrical characteristics of the nickel-coated particle with cracks. The particle resistance of the nickel-coated particle with cracks was found to be much higher than that of the particle without crack in the optimized bonding pressure range, indicating that it is necessary to take the crack into consideration for the particle conduction analysis as well. Therefore, the fracture analysis on the conductive particle by taking the crack into consideration could accurately evaluate the reliability of ACA interconnection and avoid serious reliability issues.     

计算机高速并行通信的实现方案

利用CPLD芯片实现单片机与ISA总线接口之间的高速并行通信，给出系统的总体设计方法及程序框图。采用这种通信方式，在12MHz晶振的MCS51单片机控制的数据采集系统中，可以满足与PCI04 ISA总线接口实时通信的要求，通信速率达200khit／s。在开发工具MAX plusⅡ下，完成了整个设计的输入、编译和仿真，达到了预期效果。本设计方案能够推广应用到计算机的高速并行通信中。     

Plasma spraying of nanostructured partially yttria stabilized zirconia powders

Nanosized partially yttria stabilized zirconia particles, prepared using a co-precipitation method, were reprocessed into agglomerate powders using two methods for plasma spraying. The first method was to make micrometer-sized agglomerates directly following the grinding of the calcined yttria–zirconia agglomerates. The second method was to reconstitute the nanosized particles into micrometer agglomerates using spray drying. The deposition efficiency, porosity, microhardness and average grain size of the deposits made from these two reprocessed powders were studied. Distinct results related to the process parameters were obtained for the two types of powders. The second type of powder was more suitable for plasma spraying than the first one. Using the second type of powder, some unique results distinguished from those of the conventional partially yttria stabilized zirconia powders were observed and an optimized coating with a porosity of 3.8%, Hv_0.3 of 953 and mainly consisting of 1–3 μm columnar grains in the columnar direction and smaller than 100 nm in their cross-sections was achieved.     

贵冶二期闪速炉失重给料螺旋运行实践

本文介绍了贵冶失重给料螺旋的性能、生产准备、点检维修、技术攻关、缺陷改进。     

RTK技术在黄土塬地震勘探测量中的应用

在对RTK技术进行简要介绍的基础上，叙述了这一技术在黄土塬地区地震勘探测量中的应用，及所取得的良好测量资料。     

薄板坯连铸生产SS400钢工艺技术研究

对唐钢薄板坯连铸机生产的SS400钢的生产工艺进行了分析,认为薄板坯连铸机生产的SS400钢,在采取了精炼站在线定氧,将钢水全氧控制在25×10~(-6)左右,同时连铸采取保护浇注和轻压下等技术后,能够确保薄板坯连铸SS400钢的顺利浇注,轧制的板带材表面质量良好,机械性能符合要求。     

扇形段电磁搅拌对82B钢连铸坯成分和组织的影响

进行了结晶器搅拌和结晶器 +扇形段电磁搅拌连铸 82B钢 2 80mm× 380mm方坯的工业试验。结果表明 ,扇形段搅拌降低和改善了铸坯的中心偏析、疏松和夹杂物分布。 82B钢铸坯经扇形段搅拌后 ,中心部位碳含量峰值明显减小 ,碳偏析指数降低 5 7%～ 1 0 8% ,铸坯成分的方差值 (σ)减小 32 %～ 34 9%。