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1.
谢应涛 《大众科技》2010,(4):63-64,51
在全局光照渲染模式下,最常用的方法是光辐射的方法,由于光辐射法对于光线的反射计算量过大,一般只用于静态渲染.使用蒙特卡罗随机积分的方法来产生光照,可以减少计算量,达到动态产生全局光照的效果;使用分层的方法使光能辐射能使用于各种反射情况和复杂物体表面,同时可以减少随机光线产生的噪点.介绍一种通过以随机光线和物体反射表面分层渲染的思想来达到实时动态的光能辐射方法。  相似文献   

2.
郑海滨 《科技风》2011,(23):37+43
本文分别介绍用灯光模拟、光能传递、光影追踪和基于点云等方法实现三维影像的全局照明渲染,介绍了目前GPU在全局照明渲染计算上的应用情况,并分析了未来渲染技术的发展趋势。  相似文献   

3.
伴随着数据库技术以及海量数据不断产生,如何最大限度的挖掘数据成为了目前云计算下环境下的研究热点,本文首先分析了云计算下的聚类算法存在的不足,其次,将模拟退火算法和遗传算法运用到聚类分析中,依靠模拟退火算法的良好局部搜索能力和遗传算法的全局搜索能力,构造矢量量化器,提高聚类的效果。通过仿真实验说明,本文算法在标准效率,加速比和扩展效率方面都具有明显的提高。  相似文献   

4.
耿强  黄雪琴 《科技通报》2019,35(8):129-133
针对云计算下的负载均衡存在效率低的问题,本文首先在鲸鱼算法的基础上,通过种群初始化,淘汰和竞争机制提高算法的局部搜索能力,然后通过人工蜂群算法进行融合提高算法全局搜索能力,融合后算法用于云计算负载均衡中,在调度时间跨度,负载均衡度和任务平均等待时间方面都具有较好效果。  相似文献   

5.
葛伟宽  王保平 《科技通报》2019,35(11):72-75,80
针对传统方法无法有效解决物流机器人一次访问若干点的全局路径规划问题。为此,提出一种基于栅格图法的移动物流机器人全局路径规划方法。通过栅格图法构造容易被移动物流机器人理解的仓储环境。在不考虑点和点间准确路径的情况下,按照移动物流机器人初始点是否处于出口,把全局路径规划问题划分成典型的TSP问题和TS-TSP问题,针对典型的TSP问题,将全局路径点看作种群个体,针对TS-TSP问题,将中间节点看作种群个体,以此构建移动物流机器人全局路径规划数学模型,并通过势场蚁群法对其进行求解,获取全局路径点的最优访问顺序,在此基础上,通过A*法计算准确的移动物流机器人全局路径规划结果。实验结果表明,采用所提方法收敛速度快,可快速得到全局最优解,且全局路径规划结果所需时间少,实用性强。  相似文献   

6.
基于改进遗传算法的堆垛机调度路径建模与优化研究   总被引:1,自引:0,他引:1  
为提高广东电网计量检定中心自动化立体仓库的堆垛机出入库作业效率,详细分析了堆垛机出入库的作业方式,建立了数学模型,提出了一种基于改进遗传算法的路径优化方法。该方法在寻找全局最优解时引入了贪心交叉算子和高斯变异算子,提高了该算法全局的搜索能力。仿真实验结果表明该方法能提高堆垛机出入库作业的效率,在路径的优化方面达到了满意的效果。  相似文献   

7.
在对云计算网络漏洞进行检测的过程中,涉及的数据量巨大,传统方法依据先验知识建立云计算网络漏洞库,通过和漏洞库的匹配实现漏洞检测,实现过程非常复杂,且建立的漏洞库也存在局限性,检测精度低,因此,提出一种基于风险数据挖掘追踪的云计算网络漏洞检测技术。将特征相关性看作是计算数据差异的依据对风险数据进行初聚类,将和风险数据有较大差异的正常数据剔除,完成初步的处理。引入模糊关联规则,依据风险数据属性关联规则,对经初聚类处理后的风险数据进行挖掘追踪,构成云计算网络漏洞数据库,通过隶属度分布函数对漏洞数据库的连续属性进行模糊处理,依据模糊关联规则挖掘构建云计算网络存在漏洞状态时的关联规则集,用相似度对云计算网络当前状态和存在漏洞状态的背离程度进行描述,实现云计算网络的漏洞检测。仿真实验结果表明,所提方法具有很高的检测精度和检测效率。  相似文献   

8.
地球面在接受太阳光照的过程中,存在着光照直射的区域,必然有一条光线与地球半径的延伸线重合,无论传播光线在大气层中是否发生折射,这条光线方向都不改变,这就是大气层传光过程中的主光轴。从高中物理知识中可以知道"大气层对太阳光以及从其他星球射过来的光确有折射作用,天边恒星射过来的光线最多偏转37分,天顶恒星的光线不偏转。"传播光线存在了折射,便存在了人们分析折射过程中的法线,大气层在地球周围以地球重力的吸引而存在,大气层中每一个折射点的法线就是这一点地球半径的延伸线。当我们把发生平面折射的折射面逐渐倾斜,入射角会随之逐渐增大,折射角也会随入射角的增加而逐渐增大,折射光线的偏转聚集逐渐增强,这也就是大气层传播折射光线的基本方式。  相似文献   

9.
本文介绍了基于VRAY渲染器的三维动画场景灯光照明及渲染系统的设置方法,以动画场景为例,详细讨论了如何解决三维动画灯光照明及渲染成图的一些关键技术,如全局光照、HDR技术的运用、集群渲染技术的实现等。  相似文献   

10.
针对云计算下的任务调度存在花费时间长、消耗成本高和负载率大等缺点,提出了一种改进的鲸鱼算法用于云计算中的任务调度。首先,提出了以时间、成本和负载为主要指标的云计算任务调度模型,其次使用改进的鲸鱼算法进行任务调度,采用改进的Bernouilli Shift混沌映射进行了种群初始化提高种群的多样性,使用自适应因子优化参数平衡了局部和全局搜索的能力,使用差分算法进行个体更新。最后在仿真实验中将本文算法进行与其他算法进行对比,实验结果说明本文算法具有一定的优势,能够有效的提高云计算下的任务调度效率。  相似文献   

11.
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.  相似文献   

12.
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China's science enterprise by making S&T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party's Leading-member Group at CAS, which was held from 7 to 11 January in Beijing.  相似文献   

13.
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.  相似文献   

14.
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants."  相似文献   

15.
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.  相似文献   

16.
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.  相似文献   

17.
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction.  相似文献   

18.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.  相似文献   

19.
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment.  相似文献   

20.
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.  相似文献   

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