热处理工艺对2.25Cr1MoR钢组织和力学性能的影响

本文研究了热处理工艺对2.25C r1M oR钢组织和力学性能的影响。结果表明,该钢在780℃时可获得良好的强韧化效果和较高的抗回火脆性能力,在此基础上得到了该钢板生产制造的热处理工艺参数。实践证明,该工艺合理可行。     

Sliding mode control for two-time scale systems: stability issues

The paper presents some results on global exponential stability of linear time invariant systems with different time scales. The full system is decomposed in two reduced ones by means of singular perturbations and a smooth approximation of a Variable Structure Control is synthesized for each of them using Reaching Law approach. The global closed loop stability is then proved for the whole system using Lyapunov methods and a particular state space decomposition. Moreover a literal form for ε∗ (a parameter which measures the minimum separation between time scales) is derived.     

提升小波实现技术的优化改进

回顾了提升小波的发展，以及它在信号处理领域的广泛应用，讨论了在实际应用中考虑节约存储器容量、提高硬件利用率和增加处理速度等便于VLSI实现因素而进行的改进措施。     

居住区环境设计新思维初探──跨世纪住宅设计竞赛的思考与研究

本文结合’96上海国际住宅设计竞赛方案，就居住区环境设计的理论与方法进行了探讨。     

State-variable planning under structural restrictions: algorithms and complexity

Computationally tractable planning problems reported in the literature so far have almost exclusively been defined by syntactical restrictions. To better exploit the inherent structure in problems, it is probably necessary to study also structural restrictions on the underlying state-transition graph. The exponential size of this graph, though, makes such restrictions costly to test. Hence, we propose an intermediate approach, using a state-variable model for planning and defining restrictions on the separate state-transition graphs for each state variable. We identify such restrictions which can tractably be tested and we present a planning algorithm which is correct and runs in polynomial time under these restrictions. The algorithm has been implemented and it outperforms Graphplan on a number of test instances. In addition, we present an exhaustive map of the complexity results for planning under all combinations of four previously studied syntactical restrictions and our five new structural restrictions. This complexity map considers both the optimal and non-optimal plan generation problem.     

晶体概念新释

提出了晶体的新概念，修改了晶体中原子排列周期性的传统提法。按照晶体结构中原子是否有周期性重复排列将晶体分成了单胞晶和双胞晶两大类。     

预制挑檐的几种构造作法

挑檐是建筑屋面的一个组成部分。本文介绍了挑檐自重平衡法、屋面板压重平衡法、圈梁压重平衡法、螺栓锚固法等四种预制挑檐的构造 ,在施工过程中应根据现场环境合理选用     

Optical, electrical and structural characteristics of Al:ZnO thin films with various thicknesses deposited by DC sputtering at room temperature and annealed in air or vacuum

Transparent and conductive Al-doped ZnO (AZO) films have been grown with various thicknesses between 0.3 and 1.1 μm by magnetron sputtering at room temperature onto soda lime glass substrates. After deposition, the samples have been annealed at temperatures ranging from 150 to 450 °C in air or vacuum. The optical, electrical, and structural characteristics of the AZO coatings have been analyzed as a function of the film thickness and the annealing parameters by spectrophotometry, Hall effect measurements, and X-ray diffraction. As-grown layers are found polycrystalline, with hexagonal structure that shows some elongation of the unit cells along the c-axis, having visible transmittance ∼85-90% and resistivity ∼1.6-2.0 mΩ cm, both parameters slightly decreasing when the film thickness increases. Heating in air or vacuum produces further elongation of the crystalline lattice together with some increase of the visible transmittance and a decrease of the electrical resistance that depends on the heating temperature and atmosphere. The best characteristics have been obtained after treatment in vacuum at 350 °C, where the highest carrier concentrations are achieved, giving visible transmittance ∼90-95% and resistivity ∼0.8-0.9 mΩ cm for the AZO layers with various thicknesses. Some relationships between the analyzed properties have been established, showing the dependence of the lattice distortion, the band gap energy and the mobility on the carrier concentration.     

Structure factors of modified liquid Al–Si alloys

The structure factor and the coordination numbers of liquid Al–Si alloys with different Si content have been measured by a high temperature X-ray diffractometer. Radial distribution functions (RDFs), the nearest atomic distance and the coordination numbers of eutectic Al–Si alloys before and after being modified with Sr and Sb were studied. The RDFs of the liquid alloy were decomposed by five Gaussian peaks. The results show that a Si–Si covalent bond exists in the liquid of eutectic and hyper-eutectic alloys. Sr in the liquid Al–Si has a capability to weaken the covalent bonds of Si–Si, suppressing the nucleation of the eutectic silicon phase. On the other hand, Sb in the liquid Al–Si increases the order degree of Si atoms, decreasing the supercooling degree of the nucleation and promoting the nucleation of eutectic silicon.     

基于结构相似性和压缩变换的聚类方法

针对聚类分析在处理任意形状、任意密度和具有一定结构特征的数据集时存在的不足,首先在数据空间中建立离散拓扑流形,通过在此结构上定义邻域密度相似性和邻域密度变化光滑性两个相对性度量标准,并利用可达性给出样本结构相似性和类结构的定义,证明类结构关系是一个等价关系。然后将结构相似性当作吸引力,设计基于压缩变换的聚类方法,该方法具备处理任意形状、任意密度和解释性好等许多优点。最后在人工数据集和标准数据集上的比较实验结果表明,该方法在聚类效率和有效性上都明显优于其它聚类算法。