激光涂层零件的多冲碰撞形变效应与分析

报道了多冲碰撞载荷下激光涂层零件塑性变形现象。利用坐标网格法、显微分析法等分析了激光涂层零件的多碰累积变形现象和规律。这种塑性变形在常温即可发生,且具有低应力和累积特性。变形发生在涂层表面及以下一段区域内,并由大到小呈梯度变化。碰撞能量驱动、冲击温升效应、晶界滑动与迁移、亚结构的形成与孪晶等,是引起多碰累积变形的可能原因。     

分散有ZnS:Mn2+纳米超微粒的有机薄膜的制备和光学性质

近年来,半导体超微粒的合成及光物理性质研究已成为活跃的领域.由于量子尺寸效应引起的量子点能级结构的变化及其光学性质已经作了大量研究[1-4].1993年,Bhar-gava首次报导了化学反应合成的ZnS Mn超微粒的光学性质[5],掺杂半导体纳米材料的出现,为纳米科学的研究开辟了新的领域.     

空间有理参数多项式曲线的整数级绘制算法

讨论了空间有理曲线中心投影后导数上界的估计，基于曲线各阶差分的递推计算，给出了空间有理参数多项式曲线的快速绘制算法．算法只用到整数的加减法，效率高．     

数字电视条件接收系统的研究

条件接收系统是数字电视的关键部分,也是密码学的一种应用.从密码学的角度及信息安全的角度对数字电视条件接收系统进行了分析.     

Simulating Single Event Transients in VDSM ICs for Ground Level Radiation

This work considers a SET (single event transient) fault simulation technique to evaluate the probability that a transient pulse, born in the combinational logic, may be latched in a storage cell. Fault injection procedures and a fast fault simulation algorithm for transient faults were implemented around an event driven simulator. A statistical analysis was implemented to organize data sampled from simulations. The benchmarks show that the proposed algorithm is capable of injecting and simulating a large number of transient faults in complex designs. Also specific optimizations have been carried out, thus greatly reducing the simulation time compared to a sequential fault simulation approach.     

Enzymatic hydrolysis of steam-exploded and ethanol organosolv-pretreated douglas-fir by novel and commercial fungal cellulases

Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delignification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBC1 and MSUBC2) and two commercial cellulase preparations (TR1 and TR2) to hydrolyze cellulose in Douglas-fir pretreated by steam explosion or ethanol organosolv process. MSUBC1 showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBC1 achieved >76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (～44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without β-glucosidase supplementation.     

A Subtree-Partitioning Algorithm for Inducing Parallelism in Network Simplex Dual Updates

This paper reports on thedevelopment of a very efficient method for partitioning the networksimplex basis subtree in which dual values must be updated duringa pivot. The partitioning procedure may be concurrently executedby multiple processes. The resulting rapid decomposition of thesubtree allows an arbitrary number of processes to be utilized inthe actual dual update. This approach alleviates a primary limitationof the most efficient parallel network simplex implementationpublished to date. The new code performs at least as well as theprevious implementation on medium-scale problems and reduces averagesolution time by over 34% on large-scale problems.     

Thermal decomposition of ammonia-borane under pressures up to 600 bar

The thermal decomposition of ammonia-borane BH₃NH₃ in the temperature range up to 450 K has been studied by differential scanning calorimetry (DSC) and volumetric analysis of the released volatile decomposition products. Measurements were performed in a transitiometer ST6-VI under pressures up to 600 bar and in a DSC C-80 in the pressure range 1-100 bar hydrogen. Above 360 K ammonia-borane undergoes an exothermic decomposion, which proceeds in two steps with rising temperature. The decomposition is accompanied by hydrogen release. Formation of further volatile products, beside hydrogen, seems to be negligible. The heat evolution and hydrogen release terminates near 430 K. The final amount of released hydrogen is approximately equal to 2 mol H₂/mol ammonia-borane. Variation of pressure does not influence significantly the reaction enthalpy and hydrogen release. The transitiometer ST6-VI is well-suitable for the monitoring of solid-gas reaction under high-pressure conditions. This instrument enables a reliable determination of the reaction heat and the amount of gas release/gas uptake.     

Curve Complexes and Finite Index Subgroups of Mapping Class Groups

Let Mod(S) be the extended mapping class group of a surface S. For S the twice-punctured torus, we show that there exists an isomorphism of finite index subgroups of Mod(S) which is not the restriction of any inner automorphism. For S a torus with at least three punctures, we show that every injection of a finite index subgroup of Mod(S) into Mod(S) is the restriction of an inner automorphism of Mod(S); this completes a program begun by Irmak. We also establish the co-Hopf property for finite index subgroups of Mod(S).Dan Margalit: Partially supported by an NSF postdoctoral fellowship     

Propagation of very short pulses at millimeter wavelengths through rain filled medium

Distortion of pulses with pulse widths ranging from 0.1 to 1 ns propagating with carrier frequencies in the range 10–100 GHz through rain filled medium has been estimated considering the absorptive and dispersive effects produced by rain drops on the propagation of millimeter waves. It is found that the rain induced broadening or compression can be quite appreciable for very short pulses in the window region of millimeter wave band under intense and extensive raining conditions.