长轴类零件开式挤压工艺应用及成形极限研究

长轴类零件开式挤压失稳包括弹性失稳和塑性失稳。将压杆失稳原理应用于开式挤压,得到了开式挤压弹性失稳的临界长径比及临界挤压应力的计算方法,建立了开式挤压工艺弹性稳定性校核模型,提出了提高抵抗弹性失稳能力的措施,如降低挤压应力、采用夹持器支承等方法。分析塑性失稳的原因,是零件的传力段的应力达到材料的屈服应力,而在入模口处出现局部镦粗。用上限法计算了圆截面件开式挤压应力,并绘制成可方便查阅的线图。提出了挤压变形程度、凹模半锥角、润滑状态及摩擦因子等是影响塑性失稳成形极限的主要因素,并结合计算线图给出了各影响因素的合理范围。以汽车传动花键轴开式挤压为例,应用失稳理论对挤压工艺参数的合理制定进行指导。     

Interference automata

We propose a computing model, the Two-Way Optical Interference Automata (2OIA), that makes use of the phenomenon of optical interference. We introduce this model to investigate the increase in power, in terms of language recognition, of a classical Deterministic Finite Automaton (DFA) when endowed with the facility of interference. The question is in the spirit of Two-Way Finite Automata With Quantum and Classical States (2QCFA) [A. Ambainis, J. Watrous, Two-way finite automata with quantum and classical states, Theoret. Comput. Sci. 287 (1) (2002) 299–311] wherein the classical DFA is augmented with a quantum component of constant size. We test the power of 2OIA against the languages mentioned in the above paper. We give efficient 2OIA algorithms to recognize languages for which 2QCFA machines have been shown to exist, as well as languages whose status vis-a-vis 2QCFA has been posed as open questions. Having a DFA as a component, it trivially recognizes regular languages. We show that our model can recognize all languages recognized by 1-way deterministic blind counter automata. Finally we show the existence of a language that cannot be recognized by a 2OIA but which can be recognized by an O(n³)$O\left(n^3\right)$ space Turing machine.     

专业课程小型题库管理系统的研究

通常的题库管理系统都要根据教育测量理论．选择样本组进行测量,然后根据测量统计分析的结果,修改或选择合适的测试题以完成题库建设。大学计算机课程的自身特点。使其在选用通用题库系统时存在局限性。该题库一方面充分发挥教师的主动性．另一方面借鉴经典测量理论增强其规范性。     

Continuum structural topological optimizations with stress constraints based on an active constraint technique

Stress‐related problems have not been given the same attention as the minimum compliance topological optimization problem in the literature. Continuum structural topological optimization with stress constraints is of wide engineering application prospect, in which there still are many problems to solve, such as the stress concentration, an equivalent approximate optimization model and etc. A new and effective topological optimization method of continuum structures with the stress constraints and the objective function being the structural volume has been presented in this paper. To solve the stress concentration issue, an approximate stress gradient evaluation for any element is introduced, and a total aggregation normalized stress gradient constraint is constructed for the optimized structure under the r?th load case. To obtain stable convergent series solutions and enhance the control on the stress level, two p‐norm global stress constraint functions with different indexes are adopted, and some weighting p‐norm global stress constraint functions are introduced for any load case. And an equivalent topological optimization model with reduced stress constraints is constructed,being incorporated with the rational approximation for material properties, an active constraint technique, a trust region scheme, and an effective local stress approach like the qp approach to resolve the stress singularity phenomenon. Hence, a set of stress quadratic explicit approximations are constructed, based on stress sensitivities and the method of moving asymptotes. A set of algorithm for the one level optimization problem with artificial variables and many possible non‐active design variables is proposed by adopting an inequality constrained nonlinear programming method with simple trust regions, based on the primal‐dual theory, in which the non‐smooth expressions of the design variable solutions are reformulated as smoothing functions of the Lagrange multipliers by using a novel smoothing function. Finally, a two‐level optimization design scheme with active constraint technique, i.e. varied constraint limits, is proposed to deal with the aggregation constraints that always are of loose constraint (non active constraint) features in the conventional structural optimization method. A novel structural topological optimization method with stress constraints and its algorithm are formed, and examples are provided to demonstrate that the proposed method is feasible and very effective. © 2016 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.     

Process Yield for Multivariate Linear Profiles with One‐sided Specification Limits

The new investigation of profile monitoring is focused mainly on a process with multiple quality characteristics. Process yield has been used widely in the manufacturing industry, as an index for measuring process capability. In this study, we present two indices and to measure the process capability for multivariate linear profiles with one‐sided specification limits under mutually independent normality. Additionally, two indices and are proposed to measure the process capability for multivariate linear profiles with one‐sided specification limits under multivariate normality. These indices can provide an exact measure of the process yield. The approximate normal distributions for and are constructed. A simulation study is conducted to assess the performance of the proposed approach. The simulation results show that the estimated value of performs better as the number of profiles increases. Two illustrative examples are used to demonstrate the applicability of the proposed approach. Copyright © 2015 John Wiley & Sons, Ltd.     

一种考虑交通限制信息的道路网络模型

随着城市交通网络的发展,实际道路中的交通限制信息使得道路网络中的最优路径规划变得更加复杂,针对这一问题,笔者讨论了一种考虑交通限制信息的道路网络模型,并详细阐述了该模型的存储方法及各种常见交通限制信息的解决方案,然后给出了利用此模型求解最优路径的改进的Diiktra算法描述。最后,笔者根据北京市道路数据建立道路网络,通过实际数据进行验证,实验结果表明,该模型及算法能满足实际道路网络的最优路径分析的需要,具有一定的应用价值。     

绘画创作意象论

中国古典美学体系实质上是以"意象"为基础范畴的审美本体体系,绘画美学则侧重于从艺术的角度看待审美,所以"意象"就成为美学本体论的基本范畴。中国古典美学将"象"作为本体之基,是通过对"象"的观察去把握"道",中国绘画创造的思维过程实质上就是意象的思维过程。本文立足从中国画的创作思维的角度探究意象的形成步骤,以达到对情和景二种基本因素构成的"意象",这一中国古典美学的审美本体做出全面的诠释。     

Electrochemical determination of imidacloprid using nanosilver Nafion/nanoTiO2 Nafion composite modified glassy carbon electrode

A novel biocompatible environment friendly nanosilver Nafion^®/nanoTiO₂ Nafion^® modified glassy carbon electrode was prepared by a simple procedure and characterized. This modified electrode was used as a sensing electrode for the detection of imidacloprid. Cyclic voltammetry, differential pulse voltammetry and amperometry were used in this work. The reduction potential of imidacloprid on this electrode is lower compared to other electrodes reported in the literature. The LOD and LOQ values obtained for the sensing of imidacloprid on this modified electrode are comparable to the values reported in the literature.