改进的点集凸包的增量算法

凸包是计算几何中得到广泛研究的问题之一,在图像处理、地理信息系统中有着广泛应用.对传统点集快速凸包算法进行改进,在脱机算法中首先进行排序,通过比较当前凸壳中极值点与新增点来避免一些不必要的运算.在联机算法中,通过保持一个各方向极值点的表来快速确定新增点的粗略位置,排除对凸包内的点的运算,并有效减少了不必要的运算.算法可使用双向链接表或栈这样的数据结构.整个过程达到复杂度下限.本算法结构清晰,易于编程实现.     

无约束最优化问题的二次梯度算法

根据无约束最优化问题的梯度算法,提出了二次梯度算法,并证明了其收敛性。     

A Multiagent Approach to Modelling Complex Phenomena

Designing models of complex phenomena is a difficult task in engineering that can be tackled by composing a number of partial models to produce a global model of the phenomena. We propose to embed the partial models in software agents and to implement their composition as a cooperative negotiation between the agents. The resulting multiagent system provides a global model of a phenomenon. We applied this approach in modelling two complex physiological processes: the heart rate regulation and the glucose-insulin metabolism. Beyond the effectiveness demonstrated in these two applications, the idea of using models associated to software agents to give reason of complex phenomena is in accordance with current tendencies in epistemology, where it is evident an increasing use of computational models for scientific explanation and analysis. Therefore, our approach has not only a practical, but also a theoretical significance: agents embedding models are a technology suitable both to representing and to investigating reality.

The Chinese ‘‘HumanFlesh’’ Web:the first decade and beyond

Human flesh search （HFS）, a Web-enabled crowd- sourcing phenomenon, originated in China a decade ago. In this article, we present the first comprehensive empirical analysis of HFS, focusing on the scope of HFS activities, the patterns of HFS crowd collaboration process, and the characteristics of HFS participant networks. A survey of HFS participants was conducted to provide an in-depth understanding of the HFS com- munity and various factors that motivate these participants to contribute. This article also advocates a new stream of Web science and social computing research that will be important in predicting the future growth and use of the World Wide Web.     

Acetone hydrogenation in exothermic reactor of an isopropanol–acetone–hydrogen chemical heat pump: effect of intra-particle mass and heat transfer

Intra-particle mass and heat transfer plays an important role in performance of the exothermic fixed-bed reactor for an isopropanol-acetone-hydrogen chemical heat pump. In this work, an exothermic fixed-bed reactor model, taking into account the actual packing structure, is established in the commercial software Fluent. A 120° segment of a tube with tube-to-particle diameter ratio （n） of 4, where realistic particles are packed and set to porous media, is used to simulate the 3D external flow, concen- tration and temperature fields in the exothermic packed-bed reactor. The influence of catalyst particle diameter （dp） and micropore diameter （do） on the intra-particle temperature, species distribution, reaction rate and selectivity is dis- cussed. The appropriate dp and do are obtained. Simulation results showed that intra-particle temperature gradient is not obvious. Large dp and small do lead to remarkable gradient of reaction rate inside the catalyst particle and the decrease in the catalyst efficiency and reduce the acetone conversion and the selectivity in isopropanol. The optimal results reveal that the spherical catalyst with dp of 1 mm and dpore of 10 nm is appropriate for high-temperature acetone hydrogenation.     

伞罩除尘器内黑烟颗粒浓度分布特性的数值分析

采用FLUENT软件模拟了伞罩除尘器内黑烟颗粒浓度的分布特性.在气相和颗粒相分别选用雷诺应力模型(RSM)和离散相模型(DPM)的基础上,计算了入口含尘质量浓度(1～7 g/m3)、入口气速(10～16 m/s)和黑烟颗粒粒径(0.24～11μm)对伞罩除尘器内黑烟颗粒浓度的轴向和径向分布的影响.模拟结果表明:黑烟颗粒...     

自动武器凸轮传动分析的数值法

本文对自动武器凸轮机构工作时的分析计算提供一种数值方法。主要研究和确定了若干典型凸轮机构工作构件位移与基础构件位移的解析函数式,重新推导了相应的传速比和传动效率。它为编制通用计算程序提供了理论依据。     

火药气体作用时期活塞运动诸元的数值解法

本文介绍导气式自动武器在火药气体作用时期内活塞运动诸元的数值解法,据气体动力学原理建立的理论公式,必须采用数值解法才能求解。数值解法中用龙格一库塔法比差分解法更为简便,精度也较高。并编制了一个计算活塞运动诸元?导气装置结构诸元的通用程序,利用它对四种不同的导气式武器进行了计算,结果与实际比较符合。     

一种改进型无线传感器网络HCRL定位算法

节点定位是无线传感器网络应用的基础,是其关键技术之一.随着无线传感器网络应用的不断发展.改善定位算法成为最急迫和最具挑战性的工作.笔者详细地分析了HCRL定位算法的原理和过程,在继承了HCRL低系统通信开销优点的基础上,针对其在计算复杂度和定位精度方面的不足,应用四种改进策略,提出了一种改进算法IMP-HCRL.仿真实验表明:IMP-HCRL定位算法不仅保持了HCRL在节省系统通信量上的优势,同时提高了定位精度,降低了系统的计算复杂度.     

基于坐标法的涡喷发动机特性计算①②

压气机特性数据是通过大量实验而获取的,结合发动机调节规律对压气机特性数据进行计算,可获得整台发动机的特性,从而缩短发动机研制周期。该文根据某研制中的压气机特性数据,使用坐标数值方法对航空发动机特性进行了计算研究,且基于VB语言开发了相关的程序,实现了高压压气机和低压压气机共同工作线的计算、绘制以及发动机的特性的计算。