基于行车轨迹通信算法

随着城市中汽车数量的大增,汽车与汽车之间的通信系统显得尤为重要。因此互联网在行车过程中起到了重要的作用,其中的车载网便扮演着物物通信的功能。本文提出行车过程中复杂特性的分发算法,首先对多个城市中的汽车进行汽车行动路线的统计与分析,其中包含了通信车辆之间的距离、所连车辆的数量分布以及聚集指标,从结论分析得到车与车之间联系的数量呈现一定的指数分布;并且在小范围内,聚集指标比较高。根据上述特性分,推算出一种车辆行进轨迹数据的分发算法,以便于进行车辆与车辆的实时通信,这样就能大大提高车辆行驶的有效性和降低车祸之间的发生。     

Microstructural evidence for short-circuit oxygen diffusion paths in the oxidation of a dilute Ni-Cr alloy

A comparative study of high-temperature oxidation of Ni containing 1 at.% Cr and pure Ni was carried out. Instead of the conventional kinetics study using thermogravimetry, a microlithographic marker experiment was designed. Observation of the markers using cross-sectional TEM and SEM has revealed striking differences in the scale morphology, microstructures, and oxidation mechanisms between pure Ni and the Cr-doped Ni substrates. In particular, the results suggest that a small addition of Cr promotes significant inward transport of oxygen. Marker experiments revealed that NiO grown on pure Ni is wholly attributable to outward-cation diffusion. In contrast, NiO grown on Ni–1 at.% Cr exhibited formation of a substantial inner layer having a submicron grain size, established by the markers to have formed from oxygen ingress. For pure Ni, voids were observed to be distributed only within oxide grains. In contrast, for Ni containing 1 at.% Cr, elongated pores formed extensively along oxide-grain boundaries. Formation of new fine-grain oxide in these pores was observed to have sometimes completely resealed the void. It is, therefore, proposed that the transport of oxygen in the case of oxide scale grown on Ni–1 at.% Cr occurs via voids (pores) formed by vacancy coalescence at the grain boundaries.     

Synthesis of Dimethyl Carbonate from Methanol and Carbon dioxide using Potassium Methoxide as Catalyst under Mild Conditions

Pd-supported on WO₃–ZrO₂ (W/Zr atomic ratio=0.2) calcined at 1073 K was found to be highly active and selective for gas-phase oxidation of ethylene to acetic acid in the presence of water at 423 K and 0.6 MPa. Contact time dependence demonstrated that acetic acid is formed via acetaldehyde formed by a Wacker-type reaction, not through ethanol by hydration of ethylene.     

分子蒸馏过程模型化研究进展

介绍了分子蒸馏基本原理和常用分子蒸馏设备 ,系统地对分子蒸馏过程模型化的研究进展情况进行了叙述 ,重点介绍了蒸发系数法、液体内部传质传热和蒸馏区惰性气体压力对分子蒸馏的影响等方面的研究结果 ,并对其进行了评述 ,同时对分子蒸馏过程研究的进一步发展提出了一些展望。     

多层水平气流带式干燥机的数学模型

根据干燥传质传热学原理和干燥动力学特性，建立了水平气流带式干燥机干燥过程的数学模型。该模型可以预测干燥机合理的通风道高度、带翻转最佳时间和热风风速等。为优化多层带式干燥机的结构或设计新的水平气流带式干燥机提供了理论依据。     

分子蒸馏技术与日用化工(Ⅰ)——分子蒸馏技术的原理及特点

介绍了分子蒸馏技术发展简况，并从分子运动平均自由程的定义出发，介绍了分子蒸馏技术的基本原理、特点以及与常规蒸馏、超临界萃取与层析分离等方法的不同。分子蒸馏操作温度低、受热时间短及分离效率高，特别适用于热敏性物质的提纯，有广阔的应用前景。     

基于分层的改进A＊算法在路径规划中的应用

智能交通中的路径诱导系统能够极大地提高人们的出行效率与出行体验。经典A＊算法只注重搜索精度而忽略了搜索效率,在城市道路网络分层的基础上,对高层道路使用的A＊算法进行了改进,对于道路网络中的不同节点,设置估价函数具有不同的权值,同时给定权值的一个上下限阈值,以平衡算法的搜索效率与搜索精度。实验表明,得到的最短路径虽然不是常规的距离最短却是实际行驶时间最优的。     

Tool path generation framework for accurate manufacture of complex 3D sheet metal parts using single point incremental forming

The prototyping of complex sheet metal parts using single point incremental forming (SPIF) requires the generation of optimal tool paths and/or tool path sequences that ensure that the formed part is within geometric design specifications. The presence of a multitude of features on complex parts leads to multiple inaccuracy inducing phenomena occurring simultaneously due to interactions between the features. This paper proposes a network analysis methodology using topological conceptual graphs to capture the effects of different phenomena on the final accuracy of a sheet metal part manufactured by SPIF. Using this framework optimized tool paths can be generated that compensate for the inaccuracy inducing behavior. Tool path generation algorithms to create partial tool paths that account for the accuracy of specific features in the part based on the proposed framework are also presented. Finally, the creation of integrated tool paths maintaining complementarity between tool paths and desired continuity behavior using non-uniform cubic B-splines is illustrated. A number of case studies demonstrating the applicability of the integrated framework are discussed, where the maximum deviations in the part are significantly reduced and the average absolute deviations for the complete part are brought down to less than 0.5 mm.     

杭州市城西地区洪水出路研究

杭州市城西地区地势低洼,上承山水,下受杭嘉湖平原河流水位顶托,为易受洪涝灾害地区。以抵挡2007年"罗莎"台风洪水为目标,根据城西地区水系分布、城市布局,初步提出了洪水外排、湿地调蓄、建圩挡水的排涝布局及10种洪水出路方案。对10个方案从水位、水量、工程投资、对周边地区影响、政策处理等方面进行比较,最终提出以建设西溪湿地至钱塘江的地下排水通道、西溪湿地内部调蓄、分区建圩的组合方案为推荐方案。经分析认为,推荐方案可有效减轻杭州市城西地区的洪涝问题。     

Adaptive tracking control of an autonomous underwater vehicle

This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller.