CFD simulation of micro-particle trapping under water tweezers

In early research, capture and manipulation of particles were mainly achieved by means of light, electricity and plasma in micro-fabficaton and micro-assembly. A new method is proposed using micro-water jet to form water tweezers to capture solid particles and implement position control of micro-particles. This paper analyzes the basic prin- ciple of water tweezers, and the discrete element method and smoothed particle hydrodynamics method are employed to establish a solid-liquid coupling model used in analyzing the trapping mechanism. A flow field model is set up to simulate dynamic characteristic of water tweezers based on computa- tional fluid dynamics （CFD）. Selection of boundary conditions, initial guess, solver control and convergence strategies of the model are discussed. Velocity and pressure of streamline are predicted and discussed under certain input conditions. Simu- lation results demonstrate that it is an efficiently theoretical method to eventually trap solid particles by water tweezers.     

如何培养计算思维——基于2006-2016年研究文献及最新国际会议论文

计算思维是当前国际计算机领域广为关注的重要概念,也是信息技术教育中的研究热点。计算思维是思维方式的一种,是利用计算科学的基本概念和方法,结合工程思维、数学思维等多种思维方式和特点,进行问题求解、系统建构和人类行为理解的思维过程。关注问题解决方案的形成过程,培养学生像计算机科学家那样去思考问题,是计算思维培养的宗旨。计算思维的培养不等同于程序设计或编程教学。从国际上的经验来看,可以通过多学科整合和不同教育阶段共同关注,将计算思维融入学生知识学习和问题解决过程,从而达到培养学生计算思维的目的。目前美国及欧洲各国的研究中,计算思维受到国家政策与项目支撑较多,亚洲各国在计算思维领域重视程度相对较低。计算思维教育的测评是现阶段研究的薄弱环节,是未来研究的重点内容。我国计算思维教育实践和研究刚刚起步,需要国家和相关研究机构更多重视和支持,在借鉴国外经验基础上,构建符合我国教育实践需求的计算思维培养课程体系、评价方法和教师专业发展策略。     

广义量词的计算复杂性

广义量词的复杂性有两个层次：句法层面的复杂性和语义层面的复杂性,我们集中研究了广义量词的语义复杂性。在有穷的语境中可以找出自然语言量化语句真值的复杂性。这些复杂性与图灵机中的可计算性、作为算法的意义的等价性、计算复杂性、易处理性和不易处理性等内容相关。广义量词计算复杂性已有诸多相关研究成果。     

基于问题求解思维能力培养的程序设计教学实践--以累加求和问题为例

问题求解思维是程序设计的重要特点,也是计算思维的重要形式。以累加求和问题为例,呈现了课堂教学的组织方式,详细分析了算法形成过程,有助于学生掌握问题求解的思维规律和方法,培养计算思维能力。     

Linguistic metrics for patent disclosure: Evidence from university versus corporate patents

Encouraging disclosure is important for the patent system, yet the technical information in patent applications is often inadequate. We use algorithms from computational linguistics to quantify the effectiveness of disclosure in patent applications. Relying on the expectation that universities have more ability and incentive to disclose their inventions than corporations, we analyze 64 linguistic measures of patent applications, and show that university patents are more readable by 0.4 SD of a synthetic measure of readability. Results are robust to controlling for non-disclosure-related invention heterogeneity. The linguistic metrics are evaluated by a panel of “expert” student engineers and further examined by USPTO 112(a) – lack of disclosure – rejection. The ability to quantify disclosure opens new research paths and potentially facilitates improvement of disclosure.     

系统生物学研究进展

人类基因组计划把生物学由分子生物学时代推向系统生物学时代,生物学由分解转向整合,由叙述科学转变为定量预测科学。     

滚筒洗衣机噪声分析

本文具体针对全自动滚筒洗衣机,研究其在脱水状态下以每分钟1200转运转时所产生噪声的成因,接着提出三个改进方案,然后重新研究改进方案产生的噪声大小,以此验证改进方案的有效性。本文采用CFD软件FLUENT对所有模型进行模拟仿真分析。因为是搅拌模型,所以具体计算时采用动参考系法(MRF)进行计算。通过研究发现加强筋结构会造成涡流气流,是导致噪声问题的主要成因。在各个改进方案中,填充外围第四和第五圈栅格的方案被验证为最佳方案,既起到减噪效果又能节省填充材料。     

Numerical simulation and optimization design of the EGR cooler in vehicle

The EGR （exhaust gas recirculation） technique can greatly reduce the NOx emission of diesel engines, especially when an EGR cooler is employed. Numerical simulations are applied to study the flow field and temperature distributions inside the EGR cooler. Three different models of EGR cooler are investigated, among which model A is a traditional one, and models B and C are improved by adding a helical baffle in the cooling area. In models B and C the entry directions of cooling water are different, which mostly influences the flow resistance. The results show that the improved structures not only lengthen the flow path of the cooling water, but also enhance the heat exchange rate between the cool and hot media. In conclusion we suggest that the improved structures are more powerful than the traditional one.