Study of CNG/diesel dual fuel engine's emissions by means of RBF neural network

Great efforts have been made to resolve the serious environmental pollution and inevitable declining of energy resources. A review of Chinese fuel reserves and engine technology showed that compressed natural gas (CNG)/diesel dual fuel engine (DFE) was one of the best solutions for the above problems at present. In order to study and improve the emission performance of CNG/diesel DFE, an emission model for DFE based on radial basis function (RBF) neural network was developed which was a black-box input-output training data model not require priori knowledge. The RBF centers and the connected weights could be selected automatically according to the distribution of the training data in input-output space and the given approximating error. Studies showed that the predicted results accorded well with the experimental data over a large range of operating conditions from low load to high load. The developed emissions model based on the RBF neural network could be used to successfully predict and optimize the emissions performance of DFE. And the effect of the DFE main performance parameters, such as rotation speed, load, pilot quantity and injection timing, were also predicted by means of this model. In resume, an emission prediction model for CNG/diesel DFE based on RBF neural network was built for analyzing the effect of the main performance parameters on the CO, NOx emissions of DFE. The predicted results agreed quite well with the traditional emissions model, which indicated that the model had certain application value, although it still has some limitations, because of its high dependence on the quantity of the experimental sample data.     

Transient response of piles-bridge under horizontal excitation

Moving ships and other objects drifting on water often impact a bridge's pile foundation. The mechanical model of the piles-bridge structure under horizontal forcing was established, and a time-domain approach based on Finite-difference Method was developed for analyzing the dynamic response of the piles-bridge structure. For a single pile, good agreement between two computed results validated the present approach. The slenderness ratio of the pile, the pile-soil stiffness ratio and the type of the structure influence the dynamic response of the piles-bridge structure. The computed results showed that the stiffness of the structure determines the dynamic response of the piles-bridge structure under horizontal forcing. Project (No. 001110442) supported by the Science and Technology Bureau of Zhejiang Province, China.     

激光淬火活塞顶环槽的耐磨性

研究活塞顶环槽激光淬火层的组织、耐磨性和磨损机理．激光淬火的环槽表面具有良好的耐磨性，比经原高频淬火和镀铬工艺处理的环槽的耐磨性有较大的提高．实验运行结果表明，激光淬火是提高活塞使用寿命的有效途径     

搜索引擎的发展概况与趋势

搜索引擎是随着网上信息不断丰富应运而生的一种检索工具。1994年,Internet上诞生了第一个搜索引擎W ebCraw ler,通过对网页做索引来提供检索服务。2000年,Google的出现使搜索引擎市场发生了新的变化。近年来,中文搜索引擎的发展快,数量多。搜索引擎的发展有以下趋势:数据库小型化,专业化;强化全文检索功能;检索智能化、服务个性化;语种多样化;元搜索引擎的发展;搜索服务等。     

一种降低柴油机有害排放物方法的研究

利用进气预混甲醇来降低柴油机碳烟和NOx排放量,在柴油机高负荷情况下,对喷醇柴油机与原柴油机的负荷特性与外特性进行了对比试验,试验证明采用喷醇柴油机在碳烟、NOx排放方面明显优于原柴油机。     

高等教育中教研室的建设与发展

教研室是高校"机体"中重要的"活性"细胞,对其职能和功能的重新定位,是高等教育职能实现的重要保证。本文以教研室建设存在的问题为切入点,从目标、机制、人员等方面对教研室的未来发展策略进行了探讨。     

新时期运用新的教学方法进行教学改革以提升教学质量——论“三激”教学法在公安院校警体教学中的运用

本文运用体育教学法与心理训练法对公安院校学员在警体训练中进行综合分析,在课堂教学预先设计下运用各种心理训练手段,使学员能充分掌握每节课的警务技术技能内容并达到高效、优化的程度。     

“百度一下”中“百度”的词性确定

通过对"百度"词性的辨证分析及搭配的考量,再有与"V+一下"结构语义成分做对比,我们最终确定"百度一下"是一种特殊的"V+一下"述宾短语。作为网络流行语,它的语义内涵在扩大,它的词性已经动词化。     

国外网络教学资源的发掘研究

论文提出了围绕线索深度挖掘,从而找到高质量国外网络教学资源的方法:即了解国外网络教学资源的各种特征,选择合适的搜索引擎作为检索工具,结合搜索引擎的高级语法,对初步检索结果进行分析推理。     

欧美科技论文网络共享的实践方式及发展特点

随着数字化时代的来临,网络技术的不断创新发展,科技论文亦逐步迈向期刊网络化及快速共享的道路。本文在陈述欧美国家科技论文网络共享的主要四种实践方式基础上,进一步分项探讨其发展特点,以供中国科技论文于网络共享实践发展之借鉴参考。