Design and Simulation of 6 DOF Platform System Based on Virtual Reality

在运载器运动控制领域，运动仿真平台的出现对运动控制技术的发展起着举足轻重的作用。作为模拟运载器运动的机构，运动仿真平台有着广泛的应用：(1)可以作为航空飞行模拟器，(2)可以作为机器人的模拟运动机构，(3)在娱乐界可以作为体感模拟娱乐机，(4)用作飞机、船舶、潜艇、航天器等运动载体中相关仪器设备的试验。Stewart平台机构是运动仿真平台中最著名的一种并联机构平台，Stewart平台的出现始于1965年德国学者Stewart发明的具有六自由度运动能力的并联机构飞行模拟器。目前经典的Stewart平台机构由上、下两个平台和六个可伸缩的支腿以及它们之间的连接铰链构成，其下平台通常为基台（Base-...In the field of motion control, motion simulating platform plays a significant role to improve the development of motion control technology. As a structure for simulating motions, motion simulating platform has various applications, including: simulating the flying simulator, being the simulating structure of robots, simulating the entertaining machine and doing experiments in motion carriers such...学位：工学硕士院系专业：计算机与信息工程学院自动化系_控制理论与控制工程学号：20033100

LonWorks在楼宇自动化中的应用与前景

本文在简要介绍LonWorks现场总线与楼宇自动化的基础上,给出了LonWorks技术在楼宇自动化中应用的实例,并对其发展前景进行了展望

Design of Control System with DSP for Electrical Vehicles

介绍了一种电动汽车用的全数字稀土永磁无刷直流电动机控制系统,本系统以TI公司生产的专用于数字电机控制的DSP芯片TMS320LF2407,采用DC DC变换器提升电池的电压,用IR2132驱动IPM功率开关,实现了全数字PWM控制,实践证明该系统能够降低成本,增强系统性能,同时能够胜任各种操作要求。In this paper,a digital control system rareearth permanent magnetic brushless DC motor is introduced.The system is based on TMS320LF2407 which is especially used to control digital motor produced by TI.The system is mainly made of DCDC converter which can boost the fuel cell voltage,IR2132 and IPM,implements digital PWM control.It proves that this system can reduce cost,improve system performance effectively,and can satisfy any operating requirements

Direct Fabrication of Ultrafine Electrospinning Nanofiber

采用装配有疏水铜网的新型喷头研究了超细纳米纤维的制备.静电纺丝实现之前,首先对铜网进行了疏水处理,并将其安装于喷头前端.静电纺丝过程中,聚合物溶液由精密注射泵输送至喷头处.安装于喷头的铜网可将管道内的聚合物溶液分成多股细流从铜网网孔中流出.从铜网网孔流出的溶液细流受电场力作用被拉伸成多股独立射流,并从喷头携带走聚集的正电荷.受铜网表面疏水性和射流间电荷排斥力的影响,从铜网喷射出的多股射流都将保持其独立的轨迹而不会产生聚集.疏水铜网有利于减小纺丝射流的初始直径,并获得均匀的超细纳米纤维.利用新型的电纺丝喷头成功制备了直径20~80 nM的聚氧化乙烯(PEO)和聚乙烯醇(PVA)超细纳米纤维.实验结果表明,超细纳米纤维的直径随着电纺丝溶液浓度的增加而变大.A novel spinneret assembled with Cu grid was presented in this paper to fabricate ultrafine nanofiber directly.Before electrospinning,hydrophobic treatment was performed on the Cu grid,which was then fixed at the front end of spinneret.During electrospinning,the polymer solution was transferred to the spinneret by the precise syringe pump.Through the holes in the Cu grid,polymer solution flow was divided into several smaller ones.The fine liquid flow from each hole of Cu grid was stretched into individual jets by the electric field force,and the liquid jets carried away the positive charges accumulated on the spinneret.Due to the hydrophobic treatment and the charge repulsive force between charged jets,liquid jets emanated from Cu grid kept their own tracks without aggregation.The initial diameter of liquid jet was greatly decreased by the Cu grid after hydrophobic treatment,and the smaller jet led to finer uniform nanofiber.Polyethylene oxide(PEO) and polyvinyl alcohol(PVA) ultrafine nanofiber with the diameter of 20—80 nm were fabricated by this novel spinneret,and the diameter of ultrafine nanofiber increases with the increase of polymer solution concentration.国家自然科学基金重点资助项目(51035002);国家自然科学基金资助项目(50875222

黄连素对精神分裂症患者血脂水平影响的Meta分析

目的系统评价黄连素对精神分裂症患者血脂水平的影响,为精神分裂症患者血脂干预方案的选择提供参考。方法系统检索英文数据库(PubMed、PsycINFO、Embase、Cochrane Library)和中文数据库(中国期刊全..

Soluble TREM2 ameliorates pathological phenotypes by modulating microglial functions in an Alzheimer's disease model

阿尔茨海默病（Alzheimer’s Disease, AD）是一种以渐进性认知功能丧失为主要特征的神经退行性疾病，是最为常见的老年痴呆类型。随着全球人口老龄化的加剧，AD正在成为二十一世纪最大的疾病之一。该研究首次揭示sTREM2在AD中具有重要的保护功能，提出sTREM2或可用于AD治疗的新观点，同时也进一步佐证了小胶质细胞在AD治疗中的核心作用，研究为AD等神经退行性疾病的防治开辟了新思路、提供了新靶点。 厦门大学医学院博士后钟力和硕士研究生徐颖为论文共同第一作者，陈小芬教授和卜国军教授为该论文的共同通讯作者。厦门大学的文磊、孙灏、卓仁恭等教授和美国Sanford-Burnham-Prebys医学研究所的许华曦教授共同参与了该项目的研究。【Abstract】Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial surface receptor genetically linked to the risk for Alzheimer’s disease (AD). A proteolytic product, soluble TREM2 (sTREM2), is abundant in the cerebrospinal fluid and its levels positively correlate with neuronal injury markers. To gain insights into the pathological roles of sTREM2, we studied sTREM2 in the brain of 5xFAD mice, a model of AD, by direct stereotaxic injection of recombinant sTREM2 protein or by adeno-associated virus (AAV)-mediated expression. We found that sTREM2 reduces amyloid plaque load and rescues functional deficits of spatial memory and long-term potentiation. Importantly, sTREM2 enhances microglial proliferation, migration, clustering in the vicinity of amyloid plaques and the uptake and degradation of Aβ. Depletion of microglia abolishes the neuroprotective effects of sTREM2. Our study demonstrates a protective role of sTREM2 against amyloid pathology and related toxicity and suggests that increasing sTREM2 can be explored for AD therapy.Research by the authors was supported by grants from the National Natural Science Foundation of China 81370459, 31400914 (to X.C.), 81701079 (to L.Z.), 81373999, 81774377 (to L.W.), and 81601227 (to R.Z.), grants from the Natural Science Foundation of Guangdong Province 2016A030306005 (to X.C.), 2016A030310371 (to R.Z.), grants from the Fundamental Research Funds for the Central Universities 20720180055 (to X.C.), grants from the Alzheimer's Association AARG-18-56635 (to X.C.), and C4C-15-369446 (to H.X.). NIH grants RF1AG056130 (to G.B. and H.X.), R01AG035355 (to G.B.), R37AG027924 (to G.B.), and RF1AG056114 (to H.X.), grants from the Postdoctoral Science Foundation of China 2016M600503 and 2017T100469 (to L.Z.), a grant from the Tanz Family Funds (to H.X.), and a grant from the Natural Science Foundation of Fujian Province 2016J05203 (to R.Z.).该工作得到国家自然科学基金、厦门大学校长基金、广东省自然科学杰出青年基金、美国阿尔茨海默氏症协会基金和中国博士后科学基金等的资助

Fabrication of multi-level carbon nanotube arrays with adjustable patterns

通讯作者地址: Li, L (通讯作者),Xiamen Univ, Coll Mat, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Mat, Xiamen 361005, Peoples R China 2. Xiamen Univ, Coll Chem & Chem Engn, Xiamen, Peoples R China 3. Natl Inst Adv Ind Sci & Technol, Next Generat Device Team, Res Ctr Photovolta Technol, Tsukuba, Ibaraki 3058568, Japan 电子邮件地址: [email protected] carbon nanotube (CNT) arrays with adjustable patterns were prepared by a combination of the breath figure (BF) process and chemical vapor deposition. Polystyrene-b-poly(acrylic acid)/ferrocene was dissolved in carbon disulfide and cast onto a Si substrate covered with a transmission electron microscope grid in saturated relative humidity. A two-level microporous hybrid film with a block copolymer skeleton formed on the substrate after evaporation of the organic solvent and water. One level of ordered surface features originates from the contour of the hard templates; while the other level originates from the condensation of water droplets (BF arrays). Ultraviolet irradiation effectively cross-linked the polymer matrix and endowed the hybrid film with improved thermal stability. In the subsequent pyrolysis, the incorporated ferrocene in the hybrid film was oxidized and turned the polymer skeleton into the ferrous inorganic micropatterns. Either the cross-linked hybrid film or the ferrous inorganic micropatterns could act as a template to grow the multi-level CNT patterns, e. g. isolated and honeycomb-structured CNT bundle arrays perpendicular to the substrate.National Natural Science Foundation of China 50703032 51035002 20974089 Ministry of Education of China NCET-08-0475 Natural Science Foundation of Fujian Province 2009J0602

First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow

轴承刚度与齿轮螺旋角对减速器振动噪声影响的研究

以单级圆柱齿轮减速器为研究对象,综合考虑齿轮时变啮合刚度及误差激励的影响建立了传动系统动力学模型。以轴承动载荷为激励,采用FEM/BEM方法对减速器振动与声辐射特性进行了分析,得到了齿轮箱节点动响应时域历程及声场场点噪声谱,论述了激励中各谐波成分对齿轮箱振动噪声辐射的影响。计算了不同轴承刚度的动载荷与齿轮箱声辐射特性,得到了轴承动载荷各频率成分及声辐射随轴承刚度的变化规律。对比分析了直齿轮与斜齿轮及不同螺旋角下,齿轮时变啮合刚度波动与减速器各场点位置的噪声分布情况,为减速器的减振降噪提供了理论基础

Longitudinal aerodynamic modeling and verification for air-launch-to-orbit system during stage separation

The stage separation is one of key issues for air-launch-to-orbit system. In this process, the elastic deformation of carrier causes periodic pulsation in interference aerodynamics and may lead to modal coupling and dynamics instability of spacecraft. The dynamic responses and stability of the two vehicles should be considered carefully. The CFD-based dynamic simulation method has high accuracy but requires large computation cost. In this study, a new reduced-order modeling method is developed, which is for unsteady aerodynamics of the air-launch-to-orbit system with considering the elastic deformations of carrier. Based on the physical mechanism of interference aerodynamics factors, the model input parameters are decoupled and the modeling difficulty is reduced. By coupling the unsteady aerodynamic model, structural dynamics equations and rigid body dynamic equations, the longitudinal dynamic responses of air-launch-to-orbit system during stage separation are simulated. Through comparison, those results have good agreement with traditional CFD-based method, and the simulation efficiency of new method is improved greatly. The new modeling method is applicable to the air-launch-to-orbit system and can provide guidance for similar engineering issues. (C) 2021 Elsevier Masson SAS. All rights reserved