Theoretical Analysis and Experiment on Flow Allocation Characteristics of Dual Discharging Axial Piston Pump

通过改变缸体结构、柱塞数、端盖油路、配流盘形状等,设计了双排油内外环并联配流结构的轴向柱塞泵,实现了单柱塞泵两路高压供油。针对单环柱塞数减少,腔; 内压力冲击增大,脉动变大等问题,对配流结构进行重新设计。在排油腰形槽和吸油腰形槽过渡区取消卸荷槽,利用加大配错角,在排油完毕未接通吸油时,腔内封; 闭体积增大,未排尽的高压油液压力降低;在吸油腰形槽和排油腰形槽过渡区,排油卸荷槽利用阶梯变化通流面积代替原连续变化的通流面积,削弱了卸荷槽几何形; 状要求。重新设计后的双排油配流结构,以45mL轴向柱塞泵结构为参考,对配流结构进行了理论分析,建立了双排油轴向柱塞泵仿真模型。以单柱塞腔内压力; 冲击、输出流量进行分析研究,得外环压力冲击小,与传统配流结构相比较双排油输出口压力脉动变化率变小,并试制双排油轴向柱塞泵。对试制泵进行压力脉动测; 试、容积效率测试和噪声测试,结果表明,与45mL轴向柱塞泵进行对比,压力脉动降低了约30%,噪声也降低,容积效率不低于0.92。该双排油轴向柱; 塞泵可以代替双联泵,使系统结构简化,能耗降低。When providing two-way independent high-pressure high-flow oil sources,; hydraulic system generally adopts two separate piston pumps or coaxial; ones in series, causing complex structure and high cost. Therefore,; single piston pump was proposed to achieve two-way high-pressure oil; supply. Axial piston pump was designed with dual discharging inter-outer; ring parallel allocation structure by changing cylinder structure,; piston number, cap circuit and valve plate shape. Flow allocation; structure was redesigned due to decreased single ring piston number,; increased pressure shock and fluctuation in the chamber. Relief notch; was cancelled in transition region from oil-discharging to oil-absorbing; waist slots. After that, mismatch angle was increased to enlarge closed; volume in chamber and reduce the pressure of unexhausted high-pressure; oil in the interval between oil extraction and absorption. In transition; region from oil-absorbing to oil-discharging waist slots, stepped flow; area was used to replace original continuous flow area to weaken; geometry requirements of relief notch. The optimized dual discharging; flow allocation structure was conducted with theoretical analysis to; establish dual discharging axial piston pump simulation model based on; 45mL axial piston pump structure. There was small pressure shock in; outer race by analyzing pressure shock and output flow in single piston; chamber. Compared with traditional flow allocation structure, dual; discharging oil output had smaller pressure fluctuation rate. Based on; this, the designed dual discharging axial piston pump was piloted. The; pilot dual discharging oil pump was compared with the original 45mL; pump through pressure fluctuation, volumetric efficiency and noise; tests. Result showed that the former had lower pressure fluctuation; (decreased by 30%) and noise level, while its volumetric efficiency was; not smaller than 92%. In general, the dual discharging axial piston pump; can replace duplex pump to simplify system structure and reduce energy; consumption. This new pump can also be used in closed circuit and; differential cylinder hydraulic systems to make the system simpler and; cost-effective.山西省自然科学基金项目; 国家自然科学基金项

光环境生物效应及其模拟实验装备研究进展

光是人、动物和植物赖以生存的基本条件。光环境作为一种物理环境因素,其生物效应具有十分重要的理论和应用价值。光环境对人的生理、心理及行为产生重要影响,对动物昼夜节律、定位系统和生长繁育的影响也已受到诸多关注;同时,光是植物赖以生存的基础,是植物一切生化反应的能量来源。综述了光环境生物效应的研究进展,指出已有的文献仅限于以复色光为研究对象,对特定波长的光效应、光暴露时间及光质效应的研究甚少。进一步阐明目前光环境模拟实验装备的研制所遇到的关键\"瓶颈\"是缺乏能够在一定波长范围内输出较高功率的单色光光源,且无配备生物学培养装置,不可能在实验室实现对单色光环境的模拟。因此,其发展当务之急是先构建光环境暴露的科学实验平台。同时对光环境生物效应的研究方向及光模拟实验装备的应用前景进行了展望。中国科学院科研装备研制项目(YZ201104,YZ201303);中国科学院STS计划(Y6I0921A20)资

MySQL密码认证算法的FPGA优化实现

My SQL数据库软件被广泛地应用于WEB项目中,因此它的安全性极为重要。本文针对My SQL密码认证算法的FPGA实现以及应用进行研究,利用并行化、流水线架构实现My SQL认证算法。提出一种基于BRAM的SHA-1算法流水线架构并对其流水线级数进行优化,从而实现高性能。同时利用多模块并行,多密码验证算法,以提高硬件运行速度和计算资源的利用效率。通过优化,高性能实现了基于FPGA硬件的My SQL认证算法,单块芯片的口令恢复速度为18亿个口令密码每秒,多个FPGA构成子板的认证速度为72亿/秒,比采用GPU GTX 690平台的速度提高了5倍。本研究项目获得集成电路设计与测试分析福建省高校重点实验室建设资金.厦门市科技局科技专项经费以及2017年厦门大学教学改革研究项目资金的支持

Polishing of Laser Lift-off-Induced GaN Surface

激光剥离(llO)技术是研制新型氮化镓(gAn)基谐振腔结构光电子器件的关键技术。然而llO后的gAn表面往往具有较大的粗糙度,而制作谐振腔结构器件需要很高的表面平整度,因此需要对llO后的gAn表面进行抛光。分别采用金刚石粉抛光液和胶粒二氧化硅抛光液进行机械抛光和化学机械抛光(CMP),并对比了两种方法获得的抛光结果,研究发现前者会在抛光后的gAn表面引入划痕,而采用后者可以得到亚纳米级平整度的表面。进一步的实验结果表明,胶粒二氧化硅抛光液同样适用于图形化衬底外延片激光剥离后的gAn表面抛光。Laser lift-off( LLO) is a key technology in development of new GaN-based resonant-cavity optoelectronic devices.For cavity-dependent devices,a smooth surface is highly required.However,the GaN surface after LLO is usually rough,and the polishing is necessary.The mechanical polishing of diamond powder and the chemical mechanical polishing of colloidal silica were compared.It is found that diamond powder leads to scratches on the GaN surface whereas colloidal silica leads to smooth surface with sub-nanometer roughness.The experiment results indicate that polishing with colloidal silica solutions can be applied to smoothen the LLO-produced GaN surface from an epitaxial wafer grown on patterned-sapphire substrate.国家自然科学基金资助项目(61274052;61106044); 中国科学院纳米器件与应用重点实验室开放课题资助项目(14ZS02

Melody Similarity Algorithm Based on DTW Applied in Query by Humming System

哼唱搜索由于其用户要求低,应用方便,易于普及的特点,是当前音乐搜索应用中的主流方式,而旋律的相似度计算是哼唱搜索中直接影响搜索排名结果的关键技术。动态时间规整作为度量时间序列相似性的经典方法,是旋律相似度计算的主要方法之一。根据哼唱搜索的特点,提出了一种基于dTW的旋律相似度算法,实验结果表明,该算法进一步提高了哼唱搜索结果的精准度。Query by humming is the most popular method used in music research applications for its features of user-friendly and easy to popularize.Melody similarity calculation is the key technology in query by humming which would decide the result of retrieval directly.Dynamic time warping ,as a classic method used for time based on sequence similarity measuring,is also one of the most important methods applied in melody similarity calculation.A melody similarity algorithm based on DTW is provided.The experimental results show that great improvements have been achieved by this algorithm in accuracy of the result of query by humming

A Silver Nanoparticle-Enhanced Fluorimetry for Determination of Trace Enrofloxacin in Water

在实验条件下建立了水溶液中痕量恩诺沙星的荧光分析方法;在课题组已有工作的基础上,采用“绿色“化学方法合成了银纳米粒子;研究了所制得的银纳米粒子对水溶液中恩诺沙星荧光行为的影响,并最终建立了水溶液中痕量恩诺沙星的银纳米粒子增强荧光分析方法。Firstly, a fluorimetry for determination of trace enrofloxacin in water was established in laboratory conditions.Secondly, the silver nanoparticle was synthesized based on our previous studies.In addition, effect of silver nanoparticle on the fluorescence behavior of enrofloxacin in water was investigated.Finally, a silver nanoparticle-enhanced fluorimetry for determination of trace enrofloxacin in water was also established.国家自然科学基金项目;项目号:21207103; 浙江省大学生科技创新活动计划暨新苗人才计划;项目号:2013R413010; 浙江省公益项目;项目号:2012C31025

旋转恒定磁场治疗激素性股骨头坏死的效果与病理机制

【目的】探讨旋转恒定磁场(RPMF)治疗激素性股骨头坏死的疗效和病理机理。【方法】制备新西兰兔股骨头坏死动物模型,予旋转恒定磁场(铋铁硼永磁体以8Hz频率旋转、形成其上方20cm直径60cm的半球形磁场、表面强度在0.32～0.60T之间)处理4周和8周(A1、A2组),使用组织切片和X线片以及显微CT观察股骨头内部结构变化,同时监测其血液黏稠度、胆固醇、甘油三酯以及髋关节腔压力等的变化,和相应阳性假处理4周、8周组(B1组\B2组)、空白对照(C组)进行统计学分析和比较。【结果】经旋转恒定磁场(RPMF)处理后,动物模型的股骨头骨小梁形态结构显著改善,尤以显微CT表现明显,髋关节腔压力、血液流变学及血脂检测值改善具有显著统计学意义(PEta2A*B>Eta2B)。【结论】磁场可以针对股骨头坏死主要环节高脂血症、血液黏稠度增加、关节腔压力增高等发挥调节作用,有效治疗激素性股骨头坏死,尤其是早期病变;显微CT在诊断激素性股骨头坏死方面具有灵敏性和直观的优越性

Initial Study on Management and Operation Mode of Analysis and Test Center in Universities

国家科技发展的要求,“985“、“211“工程的投入,使各高校分析测试中心面临新的机遇与挑战;新形势下如何应对,使其在学科建设、科学研究、人才培养及高新技术开发等方面发挥重要作用,寻找能够适合测试中心可持续发展的管理和运行模式,是亟待解决的问题。文中结合厦门大学分析测试中心的实际运行经验,在分析测试中心的管理和运行模式以及如何为教学、科研发展和学科建设发挥更大的作用等方面进行探讨。With the development of science and technology,especially with the input of the "985 project" and the "211 project" to universities in China,most of the analysis and test centers in Chinese universities are facing new challenges and opportunities as well.In order to play a sustainable role in subject construction,scientific research,personnel training and high technology,analysis and test centers need to solve the problems of management and operation.Based on the practical experiences of the management and running analysis and test center in Xiamen university in the past years,this paper explores the following respects:how to set up a new management and operation mode on analysis and test center,how to promote its effectiveness to subject construction,scientific research and so on

Human-oriented and mechanism innovation to promote the open sharing of large-scale instruments and equipment

提出通过加强队伍建设来促进贵重仪器设备的开放共享工作。针对实验工程技术队伍中存在的问题,提出相应的各种举措,从调整职称评价体系、设立专项基金、建立新的激励机制、加强培训、优化人员队伍结构、参与共享平台建设等方面入手,通过实验工程技术人员队伍素质和服务能力的提高,从而提高贵重仪器设备的使用率和开放共享率。This paper puts forward the facilitation of the open sharing for large-scale instruments and equipment by strengthening the technician team 's construction.Corresponding measures are presented to resolve the problems of technician team,including reforming evaluation system,setting up special funds,innovating system,enhancing training,optimizing the structure of the team and building an open-sharing platform.The utilization and open sharing rates of large-scale instruments and equipment will be increased by the improvement of technicians's quality and services capabilities

数字微流控技术及其在生物分析中的应用

数字微流控技术是一种基于微电极阵列来实现离散液滴精确控制的新型液滴操纵技术。这种基于介电润湿现象实现的液滴电操纵体系,相比于传统微流控芯片具有自动化、可寻址、可动态配置、易集成等特点。该文介绍了数字微流控技术液滴驱动原理,总结了芯片的结构和常用的制作方法,举例阐述了现阶段该技术在生物分析化学领域的应用,并对其应用前景做了展望。国家自然科学基金资助项目(21735004,21435004,21775128,21705024,21521004);;长江学者和创新研究团队项目(IRT13036