数字电位器的应用技术

从应用的角度出发，介绍合理设计应用电路和合理选择数字电位器的种类与型号，来克服数字电位器普遍存在的主要缺点的方法。文章具有较强的针对性和可操作性，对数字电位器的应用实践具有指导作用。     

PURIFICATION AND PROPERTIES OF TRANSGLUTAMINASE FROM STREPTOVERTICILLIUM MOBARAENSE

Transglutaminase (TGase) was separated from the culture broth of an isolated strain of Streptoverticillium mobaraense. The crude enzyme was prepared by centrifugation, ultrafiltration, precipitation by alcohol, centrifugation and freeze‐drying. The yield after these processes was 65–70%. Then the enzyme was purified to homogeneity by chromatography on CM‐cellulose and Sephadex G‐75 on which the yields were about 70% and 80%, respectively; the purified folds reached 2.5–4.7 and 1.08–2.06, respectively. The molecular weight of this TGase was 39,500–40,100 Da by gel filtration chromatography. Optimum enzyme activity was observed in the pH range of 5.0–7.0, and it was maintained stable at 20–40C. The optimal temperature and pH was 52C and 6.0, respectively. At 1 mM and 5 mM metal ion or inhibitors concentration, TGase activity was strongly inhibited by Zn²⁺ and NEM, and not affected obviously by Ba²⁺, Ca²⁺, Co²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Mg²⁺, Mn²⁺, Na⁺ as well as PMSF and EDTA. The effects of these additions on this TGase were compared with those of other microbial TGases.     

粉煤灰降失水水泥浆在天然气井固井中的研究与应用

长庆天然气田属于低压、低渗透气田,存在承压能力较低的地层,固井设计要求全井段封固,并且采用双级双凝施工工艺。但由于用于低密度水泥浆中的漂珠生产量降低,价格上升,研究应用替代产品是固井技术发展的方向。在一级领浆中研究应用了粉煤灰水泥浆体系,其性能和固井质量可完全满足固井要求。粉煤灰水泥浆体系价格低和固井质量优良,使其成为漂珠水泥浆体系的替代配方。     

Collision-Free Interleaver Composed of a Latin Square for Parallel-Architecture Turbo Codes

In parallel-architecture turbo codes, the constituent interleavers must avoid memory collision. This paper proposes a collision-free interleaver structure composed of a Latin square (LS) and pre-designed interleavers. Our proposed interleavers can be easily optimized for various information block sizes and for various degrees of parallelism. Their performances were evaluated by computer simulation.     

烧结成品运输自动控制系统的改进

对烧结成品运输自控系统不稳定性因素进行了分析，提出了采取优化硬件外围工作环境，完善软件保护程序等改进措施。改进后的自控系统稳定性明显提高。     

Effects of Y and Ce on Microstructures and Properties of Nb-Si System Composites

The effects of yttrium and cerium on microstructures and properties of Nb-Si system composites were investigated by scanning electron microscopy( SEM), energy dispersive spectrum(EDS), X-ray diffraction(XRD) and high temperature oxidation experiments.It is found that the coarse primary silicide phase became finer and more homogeneous with Y and Ce addition.The results of high temperature oxidation experiments show that the oxidation rates of NbSi system composites with an appropriate amount of Y and Ce decrease compared with those of alloys without Y or Ce addition, and oxidation products mainly distribute along the phase boundaries between the Nb solid solution and silicide.     

一种前馈型全摆幅恒跨导准恒增益CMOS运放设计

设计了一种适合在低电源电压下工作的前馈型输入级放大结构，在全摆幅的动态工作范围内，输入级跨导保持不变，采用负载电流补偿以保证增益近似恒定，输出采用前馈型AB类输结构，实现全摆幅输出。     

国产螺旋槽密封在进口压缩机上的应用

介绍了国产螺旋槽密封在进口压缩机上的应用，分析了原进口机械-浮环组合密封的失效原因，叙述了改造后国产浮环螺旋槽组合密封的结构和特点。     

Multi-antenna scheme for high capacity transmission in the digital audio broadcasting

In this paper, we apply multi-antenna scheme to DAB system for high-rate transmission. In the MIMO-DAB system with a number of transmitting and receiving antennas increases the transmission rate efficiently with low multiplication operations. For channel estimation in the MIMO-DAB system, we propose a new PRS structure and evaluate the channel estimation performance. The proposed PRS structure can estimate multi-channel information based on the semi-blind processing. The performance of proposed PRS is compared with that of conventional training sequence employing Tarokh's transmission matrix. And also we investigate the performance limitation due to the imperfect channel estimation in a MIMO-DAB receiver. It has been shown that the MIMO-DAB system with multi-antennas can achieve the high-rate transmission for multimedia broadcasting and the performance of MIMO-DAB system is impaired by imperfect channel information.