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

突发公共事件下的数据集成平台建设——对约翰·霍普金斯大学新冠肺炎仪表盘的调研与启示

&nbsp;[目的/意义]调研约翰&middot;霍普金斯大学新冠肺炎仪表盘快速成为此次新冠肺炎疫情大流行中全球最具权威性和影响力的数据源的成功经验,为我国突发公共事件下的数据集成平台建设提供参考启示。[方法/过程]以该仪表盘为研究对象,从响应速度、平台依托、数据质量和理念导向四个维度深入剖析其成功因素。[结果/结论]总结出对我国突发公共事件下数据集成平台建设的六点启示:强化建设服务主体责任担当意识;预先储备搭建工具包和半成品式平台框架;提升数据集成、响应速度、实时监测等服务能力;提高团队多学科协作能力、重视跨学科人才组织运用;提供充足经费保障和加强知识发现与情报咨询支持能力。&nbsp;</p

浆细胞样树突状细胞在宿主抵御隐球菌肺部感染中的作用及机制研究进展

肺隐球菌病是由隐球菌感染引起的常见真菌病,由于症状的非特异性,临床上诊断较为困难。作为条件致病性真菌感染,肺隐球菌病的结局主要与宿主免疫力有关。目前肺隐球菌病免疫学发病机制研究主要局限在T细胞和巨噬细胞。近年研究表明,作为树突状细胞亚群之一的浆细胞样树突细胞,由于其激活后可以产生大量的I型干扰素并活化相关的T细胞,所以在机体抵抗病毒和细菌免疫中发挥着重要的作用。但是浆细胞样树突细胞在真菌病,尤其是在隐球菌病的发生发展中发挥的作用尚不明确。本文将介绍肺隐球菌病的临床表现、诊治及T细胞和巨噬细胞在肺隐球菌病中的免疫机制,并通过介绍肺隐球菌病和浆细胞样树突细胞及二者之间已有报道的联系,初步阐述浆细胞样树突细胞在肺隐球菌病免疫学发病机制中的相关作用。国家自然科学基金(31770161);;上海市科学技术委员会基金(14DZ2272900);;国家卫生部基金(2018ZX10101003);;上海市科委技术标准专项(16DZ0500401)~

Predictive Study of Bubble Mean Diameter in Subcooled Flow Boiling

通道内截面汽泡平均直径是计算两相流相间界面传递方程以及计算汽液相界面浓度的重要参数。综合考虑过冷沸腾工况下汽泡动力学、两相热力学以及汽泡聚合效应; 对通道内汽泡尺寸的影响,提出过冷沸腾通道内截面汽泡平均直径预测模型。将该模型与实验数据进行比较,预测值与实验值偏差12.5%。Bubble mean diameter is a key parameter to calculate the interfacial; transfer equation of two phase flow and interfacial concentration.; Taking into account the effects of both the thermal, hydrodynamic; conditions and bubble coalescence rate on the mean bubble size in the; channel, a model has been developed. The proposed model agreed well with; the experimental data within the averaged relative deviation of 12.5%.福建省自然科学基

锂氧电池双功能还原石墨烯-LaFeO复合纳米催化剂的制备及性能

制备具有氧还原（ORR）与氧释放（OER）双功能催化活性的特殊孔道结构电催化剂是锂氧电池研究的挑战之一。本文以氧化石墨烯、硝酸铁、硝酸镧、柠檬酸为原料,结合溶胶凝胶和水热合成方法,制备出还原氧化石墨烯（RGO）与铁酸镧（LaFeO）复合的双功能催化剂（RGO-LaFeO）。X射线衍射（XRD）、傅里叶变换红外（FTIR）光谱和Raman光谱分析结果确认该复合催化剂由纯相钙钛矿结构LaFeO和还原氧化石墨烯组成,扫描电子显微镜（SEM）观察到LaFeO纳米颗粒均匀地负载在RGO片层表面。锂氧电池测试结果指出,相对于LaFeO纳米粒子（NP-LaFeO）,RGO-LaFeO催化剂具有更好的ORR和OER催化活性,归因于RGO特殊的三维导电多孔结构与LaFeO纳米粒子的协同催化作用。以RGO-LaFeO作为阴极催化剂的锂氧电池在限1000 m Ah?g比容量、100 m A?g电流密度条件下,可实现36周稳定的充放电循环,展示出良好的应用前景。国家自然科学基金(21621091)；国家重点研发计划(2016YFB0100202)资助项目~~

美国研究生负责任研究行为(RCR)教育计划及启示

介绍了美国负责任研究行为(rCr)教育的发展、教学内容、教育资源及作为美国rCr教育体系的重要组成部分的研究生rCr教育计划,并对美国rCr教育给我国研究生的科研诚信教育的启示进行了讨论

Reduced Graphene Oxide-LaFeO3 Composite Nanomaterials as Bifunctional Catalyst for Rechargeable Lithium-Oxygen Batteries

制备具有氧还原(ORR)与氧释放(OER)双功能催化活性的特殊孔道结构电催化剂是锂氧电池研究的挑战之一。本文以氧化石墨烯、硝酸铁、硝酸镧、柠檬酸; 为原料,结合溶胶凝胶和水热合成方法,制备出还原氧化石墨烯(RGO)与铁酸镧(LaFeO_3)复合的双功能催化剂(RGO-LaFeO_3)。X射线; 衍射(XRD)、傅里叶变换红外(FTIR)光谱和Raman光谱分析结果确认该复合催化剂由纯相钙钛矿结构LaFe03和还原氧化石墨烯组成,扫描电子; 显微镜(SEM)观察到LaFe03纳米颗粒均匀地负载在RGO片层表面。锂氧电池测试结果指出,相对于LaFe03纳米粒子(NP-LaFeO_3),; RGO-LaFeO_3催化剂具有更好的ORR和OER催化活性,归因于RGO特殊的三维导电多孔结构与LaFeO_3纳米粒子的协同催化作用。以RGO; -LaFeO_3作为阴极催化剂的锂氧电池在限1000 mAh·g~(-1)比容量、100; mA·g~(-1)电流密度条件下,可实现36周稳定的充放电循环,展示出良好的应用前景。Development of electrocatalysts is one of the challenges in the development of the lithium-oxygen battery, especially the synthesis of catalysts with special pore structures and excellent bifunctional catalytic performance for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). In this article, a reduced graphene oxide-LaFeO3 (RGO-LaFeO3) nanocomposite electrocatalyst was synthesized by combining sol-gel and hydrothermal methods and using graphene oxide, lanthanum nitrate, ferric nitrate, and citric acid as raw materials. The prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The results confirmed that the RGO-LaFeO3 was composed of pure phase LaFeO3 with a perovskite structure and RGO and that the LaFeO3 nanoparticles were loaded uniformly on the RGO layer surface. In comparison with a LaFeO3 nanoparticle (NP-LaFeO3) catalyst, RGO-LaFeO3 exhibited superior activity for both the ORR and the OER when it served as the cathode of a lithium-oxygen battery. The higher catalytic activity of the RGO-LaFeO3 is attributed to the synergistic effect of the special three-dimensional electronic conductive structure of RGO and the intrinsic catalytic property of LaFeO3. It was shown that the lithium-oxygen battery with the RGO-LaFeO3 cathode can be cycled stably up to 36 reversible cycles under conditions of a limit discharge depth of 1000 mAh.g(-1) and a 100 mAg(-1) current density for charge-discharge. The study illustrates that the RGO-LaFeO3 bifunctional electrocatalyst is a promising candidate for the cathode in lithium-oxygen batteries.National Natural Science Foundation of China [21621091]; National Key; Research and Development Program of China [2016YFB0100202

曲锥前体/内转进气道一体化设计与试验研究

介绍了曲锥前体/内转进气道一体化的设计方法,针对进气道侧壁外扩角这一设计因素,设计了具有不同捕获形状的两套一体化构型,并完成了两套模型在马赫数Ma=6.0、0°迎角状态下的风洞试验及数值模拟对比。结果表明,基于该一体化设计方法,曲锥前缘产生的初始入射激波在设计状态下能够完全封闭进气道唇罩,进而起到抑制唇罩溢流和提高一体化构型流量捕获能力的效果。在设计条件下,进气道侧壁外扩角的增加有助于减少侧壁产生的溢流,从而提高一体化构型的流量捕获能力。同时,外扩角的增大将导致下游反压前传速度加快,从而恶化进气道的内部流场并降低一体化构型的反压特性。因此,设计此类一体化构型时,需要考虑外扩角对捕获流量和进气道出口性能的综合影响,选择合适的进气道侧壁外扩角度以达到设计需求。国家自然科学基金项目(51606161,91441128,11602209)中央高校基本科研业务费专项资金项目(20720170055

产前滴滴涕或多氯联苯暴露与出生缺陷风险相关性的Meta分析

目的系统评价孕妇产前暴露于滴滴涕(DDT)或多氯联苯(PCBs)与新生儿出生缺陷风险之间的关系。方法计算机检索PubMed、EMbase、WanFang Data、VIP和CNKI数据库,搜集有关产前DDT或PCBs暴露与出生缺陷关系的病例-对照研究,检索时限均从建库至2017年2月。由2名研究者独立筛选文献、提取资料并评价纳入研究的偏倚风险后,采用Stata 13.0软件进行Meta分析。结果共纳入14个研究,包括2 238例出生缺陷新生儿和2 355例对照新生儿。Meta分析结果显示:产前暴露于高水平的DDT会导致新生儿隐睾发生率增加[OR=1.12,95%CI(1.09,1.15),P<0.001]。而DDT暴露与尿道下裂和神经管畸形发生没有相关性。产前暴露于高水平的PCBs与隐睾、尿道下裂、神经管畸形发生也没有相关性。结论孕妇产前暴露于高水平的DDT可能是隐睾发生的危险因素。受纳入研究数量和质量的限制,上述结论尚待更多高质量研究予以验证。厦门市科技计划项目(编号:3502Z20163006);;厦门市集美区科技计划项目(编号:20142C01

“建筑适应性”主题沙龙

"地域建筑"是当下建筑学界共同尊重的准则,但这一术语的过度使用,也使得其内涵在当代建筑创作中逐渐模糊。本期沙龙主题"建筑适应性",是对"地域建造"这一命题的具体化。"适度"的"适应"是当下应当倡导的地域建筑设计创作原则。"建筑适应性"中的"适应",强调对历史文脉与所处环境的积极回应,研究建筑与环境之间的复杂应答关联;除此,"建筑适应性"还强调对经济、技术、材料的"适度