基于PolyTrans的IGES文件简化

CAD软件与基于多边形的3D软件之间数据转换需求不断增加,但是CAD模型复杂度和精细度却越来越高,数据转换的难度变大.为了解决这一难题,结合PolyTrans,分析如何解决一般3D软件难以导入大型的IGES(Initial Graphics Exchange Specifi-cation)文件的问题.从PolyTrans模型简化模块的理论依据着手,研究如何控制多边形的数量、降低文件的复杂性和减少文件的数量,使大型CAD装配模型能顺利地以单个实体形式导入Lightwave、3DS MAX以及Maya类的3D软件.并结合具体科研项目,给出了模型优化前后各指标参数对比情况.     

Agent long-term coalition credit

Agent trust researches become more and more important because they will ensure good interactions among the software agents in large-scale open systems. Moreover, individual agents often interact with long-term coalitions such as some E-commerce web sites. So the agents should choose a coalition based on utility and trust. Unfortunately, few studies have been done on agent coalition credit and there is a need to do it in detail. To this end, a long-term coalition credit model (LCCM) is presented. Furthermore, the relationship between coalition credit and coalition payoff is also attended. LCCM consists of internal trust based on agent direct interactions and external reputation based on agent direct observation. Generalization of LCCM can be demonstrated through experiments applied in both cooperative and competitive domain environment. Experimental results show that LCCM is capable of coalition credit computation efficiently and can properly reflect various factors effect on coalition credit. Another important advantage that is a useful and basic property of credit is that LCCM can effectively filter inaccurate or lying information among interactions.     

Evaluation of Landsat 8 OLI imagery for unsupervised inland water extraction

The successful launch of the Landsat 8 satellite continues the Earth observation of the Landsat series, which has been taking place for nearly 40 years. With the increase in the band number and the improved spectral range compared with the previous Landsat imagery, it will be possible to expand the application of the new Landsat 8 imagery. The purpose of this study is to explore water extraction based on the new Landsat 8 Operational Land Imager (OLI) imagery. According to the specific inland water conditions (clear water, turbid water, and eutrophic water), a number of highly adaptable water indices are assessed for water extraction using Landsat OLI imagery. The results show that clear water is the easiest to extract among the different types of waterbodies, with the highest average accuracy of 97%. The highest-accuracy methods are the automated water extraction index for shadow pixels (AWEI_sh), the normalized difference water index using bands 4 and 7 (NDWI₄₇), and the normalized difference water index using bands 3 and 7 (NDWI₃₇), with accuracies of 98.55%, 95.50%, and 96.61%, corresponding to clear water, turbid water, and eutrophic water, respectively. Through the analysis of the different methods for optimal band selection, the seventh band OLI7 (shortwave infrared 2, SWIR-2) of Landsat OLI shows the best performance in water identification. When applying the water indices to water extraction, Otsu’s algorithm has been used to automatically select the water threshold. Using extensive experiments with Otsu’s algorithm and a manual method, it was found that Otsu’s algorithm can replace manual selection and has the ability to select an accurate threshold for water extraction.     

SM45立式球磨机结构的改进

介绍球磨机的结构和工作机理，指出球磨机存在的问题，并对其轴封、轴头、进气口、吸料口等进行了技改，以提高设备的运行周期，满足生产需求。     

SVD-based Preisach hysteresis identification and composite control of piezo actuators

In this paper, the singular value decomposition (SVD) based identification and compensation of the hysteretic phenomenon in piezo actuators are addressed using a Preisach model. First, this paper presents an SVD-based least squares algorithm and a revision approach of the identification through updating the SVD. With the identified parameters and a log of the memory curve, a Preisach-based inversion compensator is constructed which is complemented with a feedback controller to address the inevitable and residual modeling errors. Experimental results are furnished for both the identification and compensation approaches. The Preisach-based feedforward controller significantly improves the tracking performance and reduces the root-mean-square (RMS) tracking error of a PID controller by 76.7% and 89% at 1 Hz and 25 Hz, respectively. With the proposed composite controller, the percent-RMS errors at 1 Hz and 25 Hz are reduced to 0.035% and 0.31%, respectively.     

All-hexahedral mesh generation via inside-out advancing front based on harmonic fields

The generation of hexahedral meshes is an open problem that has undergone significant research. This paper deals with a novel inside-out advancing front method to generate unstructured all-hexahedral meshes for given volumes. Two orthogonal harmonic fields, principal and radial harmonic fields, are generated to guide the inside-out advancing front process based on a few user interactions. Starting from an initial hexahedral mesh inside the given volume, we advance the boundary quadrilateral mesh along the streamlines of radial field and construct layers of hexahedral elements. To ensure high quality and uniform size of the hexahedral mesh, quadrilateral elements are decomposed in such a way that no non-hexahedral element is produced. For complex volume with branch structures, we segment the complex volume into simple sub-volumes that are suitable for our method. Experimental results show that our method generates high quality all-hexahedral meshes for the given volumes.     

四川餐饮业信息化人才状况调查与分析

四川餐饮业发展迅猛,为了解餐饮企业信息化发展情况,尤其是餐饮业信息化人才状况,课题组对四川餐饮企业进行了信息化抽样调查。调查涵盖餐饮企业信息化实施总体情况,包括信息化水平、运用效果以及餐饮企业对信息化的认识,调查侧重于餐饮企业现有信息化人才结构状况和需求期待,并对调查数据进行了科学和客观分析,旨在为信息化人才标准和培养模式探索提供依据、奠定基础。     

Thermodynamic considerations of " solid state engines" based on thermoelastic martensitic transformations and the shape memory effect

Engine applications of the shape memory ("Marmem" ) effect associated with thermoelastic transformations are discussed. Such devices potentially enable the direct conversion of heat(i.e., solar energy or waste heat) into mechanical work. It is shown that efficiencies on the order of 20 pct may be expected and can be improved with alloys having certain transformation hysteresis loop characteristics. Formerly with the University of Illinois     

基于小波分析方法的装备价格指数变化研究

针对传统时间序列方法对物价指数的非平稳现象适应性较差的问题,提出运用小波分析方法,将原始数据分解成不同频率段的平稳信号,进而采用传统方法进行处理,从而提高了预测精度,获得令人满意的效果。     

一种基于CORBA的分布式全文检索系统设计

海量信息的全文检索是人类获取信息的重要手段之一,而网络海量信息的检索使传统的全文检索技术面临新的挑战。如何改善检索系统的结构,提高检索系统的性能和效率,以加快检索速度,成为一个值得研究的课题。公用对象请求代理体系CORBA技术的出现为这一课题提供了一个有效的解决方法。该文在对WEB计算方式和CORBA体系进行详细讨论的基础上,结合实际课题的研究,给出了一种基于CORBA技术的分布式全文检索系统架构设计。