Synthetic Effects of Frequency and Duty Ratio on Growth Characteristics,Energy Consumption and Corrosion Properties of Microarc Oxidized Coating Formed on Ti6Al4V

The synthetic effects of frequency and duty ratio on growth characteristics and corrosion properties of coating on Ti6 Al4 V fabricated by microarc oxidation are investigated comprehensively. Under the condition of uniform cumulating time of positive impulse width, the essence of altering frequency and duty ratio to determine the formation of coating is to vary the duration and interval time of positive pulse. The growth of coating is mainly controlled by duration time of positive pulse and hardly correlated to the interval time of positive pulse, while both duration and interval time of positive pulse have few influences on the morphology and phase structures of coating. The dynamic current is related to positive impulse width and the ratio of positive pulse on-time to pulse off-time. Regardless of uniform duration or interval time of positive pulse, the energy dissipation presents a descending tendency. The relationship between energy consumption and anticorrosion performance is contradictory, and obtaining excellent corrosion resistance is bound to sacrifice lots of energy. The duty ratio and frequency can be designed purposefully to realize the optimal process.     

油田全生命周期价值增值策略分析

基于油田全生命周期的技术和价值双重属性,通过关键技术和经济指标动态综合评价,阐述了勘探开发活动中从资源量向储量、产量及现金流转化的开发策略和流程方法,形成了油田全生命周期实现油田资产价值增值的全面管理策略。分析表明,可采储量评价、产能优化部署和投资时间价值最大化是价值增值管理的重要内容。喀麦隆X油田通过实施基于R因子约束的多阶段产能滚动部署的价值管理策略,充分发掘了新老资产的协同效益,在技术上确定了该油田的储量和产能等油藏参数,在商务上探索了油田全生命周期内实现自我滚动发展的新模式,实现了存量资产和增量资产共同增值的价值管理目标,避免了常规勘探开发建产模式投入大、周期长、储量时间价值弱化且受制于区块生命周期的问题,对国际勘探开发项目全生命周期的价值管理具有积极的参考价值。     

Electroless ultrasonic functionalization of diamond nanoparticles using aryl diazonium salts

We report a novel and very handful strategy for the functionalization of diamond nanoparticles (NDs), based on the ultrasound-assisted grafting of aryl groups from the electroless reduction of diazonium salts. For this study, 4-nitrobenzenediazonium salt was used as a model molecule and the reaction was investigated in neutral and acidic aqueous media. Spectroscopic evidence for the successful attachment of aryl groups to nanodiamonds (NDs) was given by IR and XPS which clearly detect characteristic NO₂ peaks. Moreover, the absence of any peaks from the ⁺N≡N group in the IR spectra is a clear indication of the chemical reduction of the parent diazonium salt at the surface of NDs. This spontaneous chemical modification of NDs by aryl diazonium salts was confined to the surface of the ND particles; indeed, XRD measurements have shown that the crystalline structure of the bulk of the particles was unaffected. It opens up new possibilities towards the control of the surface chemical composition of NDs using simple protocols operated in very soft conditions, i.e. in water at room temperature. It shows conclusively that the chemistry toolbox of experts interested in nanodiamonds should contain aryl diazonium salts, given their versatility in forming active platforms.     

基于Kinect骨骼跟踪技术的人机交互

基于Kinect提供的深度信息和骨骼跟踪技术进行手势识别,利用手势代替鼠标实现人机交互.首先,引入以人体为参考系的人体坐标系统,将手势位置通过坐标系变换映射到计算机屏幕,实现计算机屏幕上光标的位置显示和跟踪.其次,研究计算机操作系统响应鼠标事件的工作模式,设计固定的手势静态及动态工作模式,通过一定的映射关系将特定的一组手势与计算机系统基本操作指令进行对应.并定义状态机,根据手势状态触发系统操作事件,从而达到对计算机系统的体感控制.实验表明,该人机交互系统自然、合理、有效.     

PID参数整定的MCP标准传递函数法公式

根据MCP标准函数,利用控制器标准传递函数设计方法推导得出了一种新的PID参数整定公式.通过理论分析和仿真试验,验证了用MCP法公式整定的系统具有超调量小和鲁棒性高的优点.     

脉冲激光测距中基于多层嵌套状态机的控制系统

设计了基于FPGA与TDC-GP21的高精度、高重频的激光飞行时间测量系统。采用多层嵌套状态机作为控制系统,构建SPI通信接口实现对TDC-GP21的配置、控制以及读取测量结果。使用TimeQuest时序分析工具对系统进行时序约束分析。实验结果表明,系统重复测量频率达40KHz,测量精度达±100ps,可以在高频条件下稳定工作。     

当代大学生价值观的矛盾、成因及其解困路径

当代大学生的政治价值观、人生价值观、道德价值观、择业价值观、择偶价值观均呈现出一定的矛盾,其原因主要有五个方面,"三个结合"是大学生走出价值困境的有效路径。     

高等学校物理教学中培养学生创新能力的研究与实践

以培养创新能力为核心,根据地方院校高师教育的现状,构建"先做后学"的教学模式应用于《光学》课程中,这一模式体现了以学生为中心的教学理念,实现了教学内容和教学方式与高中物理教育相衔接,有助于构建和谐的师生关系,使课堂教学同时完成传授知识与培养能力的双重任务。     

基于多磁盘内存映射的并行湍流相屏生成方法

大气湍流仿真的核心问题是生成较高精度的多层湍流相屏。针对经典谱反演生成方法,占用大量计算机资源,且无法并行计算的问题,本文提出并实现了一种基于多磁盘内存映射的并行计算方法。该方法的基本思想是将数据量较大的文件暂存在多个磁盘上,分块映射部分数据到内存中进行并行计算,使用操作系统提供的函数接口实现了无需人工干预的分块自动化内存映射机制。实验结果表明,新方法运算速度提升明显,仿真结果较为准确。该方法不但可以解决大数据湍流相屏的并行生成,还适用于一般的大数据科学计算和计算机仿真。     

Large eddy simulation and proper orthogonal decomposition analysis of turbulent flows in a direct injection spark ignition engine: Cyclic variation and effect of valve lift

Large eddy simulation(LES)is used to calculate the in-cylinder turbulent flow field in a direct injection spark ignition(DISI)engine.The computations are carried out for three different maximum valve lifts(MVL)and throughout 100 consecutive engine cycles.The simulated results as well as corresponding particle image velocimetry(PIV)measurement database are analyzed by the proper orthogonal decomposition(POD)method.Through a new developed POD quadruple decomposition the instantaneous in-cylinder flow fields are decomposed into four parts,named mean field,coherent field,transition field and turbulent field,respectively.Then the in-cylinder turbulent flow characteristics and cycle-to-cycle variations(CCV)are studied separately upon the four part flow fields.Results indicate that each part exhibits its specific characteristics and has close connection with others.The mean part contains more than 50%of the total kinetic energy and the energy cascade phenomenon occurs among the four part fields;the coherent field part possesses the highest CCV level which dominates CCV of the bulk flow.In addition,it is observed that a change in MVL affects significantly the in-cylinder flow behavior including CCV,especially for the coherent part.Furthermore,the POD analysis demonstrates that at least 25 sample cycles for the mean velocity and 50 sample cycles for the RMS velocity are necessary for obtaining converged and correct results in CCV.