A unified analysis of a micro-beam,droplet and CNT ring adhered on a substrate:Calculation of variation with movable boundaries

In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube （CNT） ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thor- oughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materi- als, and hold potential for enhancing their mechanical, chemical, optical and electronic properties.

Compact and broadband circularly polarized ring antenna with wide beam-width for multiple global navigation satellite systems

A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.

The Calibration and Use of a New Ring-Shaped Ionization Chamber for Monitoring and Dosimetry of X-Ray Beams

Today, dosimeters are used generally for dosimetry of the diagnostic X-ray beam. Ionization chambers are appropriate instruments for monitoring and also the dosimetry of X-ray beam in medical diagnostic equipment. The present work introduces design and investigation of a new ring-shaped monitor chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick), a special graphite-foil central electrode (0.1 mm thick, 0.7 g/cm3 dense) that creating two sensitive volumes and a central hole for crossing the radiation beam with less attenuation. The results of performance tests conducted at the Nuclear Science and Technology Research Institute, AEOI in Karaj- Iran proved the high short and long-term stability, the very low leakage current, the low directional dependence and very high ion collection efficiency through the special design of the collecting electrode. Moreover, the FLUKA Monte Carlo simulations certified the negligible effect of central electrode on this new ring-shaped monitor chamber. According to the results of the performance tests, the new monitor chamber can be used as a standard dosimeter in order to monitor X-ray beam in primary standard dosimetry laboratories.

Study of orbit stability in the SSRF storage ring

In this paper, analysis of the beam orbit stability and conceptual study of the dynamic orbit feedback inthe SSRF storage ring are presented. It is shown that beam orbit position movement at the photon source points issmaller than the orbit stability requirements in horizontal plane, but exceeds the orbit stability requirements in verticalplane. A dynamic global orbit feedback system, which consists of 38 high-bandwidth air-coil correctors and 40high-precise BPMs, is proposed to suppress the vertical beam orbit position movement. Numerical simulations showthat this dynamic orbit feedback system can stabilize the vertical beam orbit position movement in the frequencyrange up to 100 Hz.

A modeling GUI for accelerator physics of the storage ring at SSRF

In this paper,we report a MATLAB-based GUI tool,bodgui,which integrates functions of lattice editor,linear match,and nonlinear optimization,and visualized tracking functions for beam optics design.A user can switch his/her design procedures one to another.Flexibilities are provided for adjusting or optimizing the lattice settings in commissioning or operation of the accelerators.The algorithm of the linear match and nonlinear optimization,and the GUI windows including the main functions and running status,are presented.The SSRF storage ring was employed as a test lattice.Several optics modes designed and optimized by the GUI tools were used for commissioning the storage ring.Functions of bodgui tool are machine-independent,and it can be well applied to modern light sources being built in other parts of the world.

Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction, an axial gradient magnetic field can be generated, with the field range changing from-Bo to Bo- A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage, it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

弹性环梁支撑下圆形深基坑支护结构变形解析解

将环梁和支护结构分别视为弹性圆环和弹性圆柱薄壳,基于环梁和圆柱壳的变形协调,得到了具有任意数目弹性环梁支撑圆形深基坑支护结构变形的解析解.在验证解析解合理性和可靠性的基础上,针对某一实际圆形基坑工程,比较了在刚性和弹性环梁支撑下支护结构变形和内力的差异,并分析了支护结构底部边界条件、环梁弹性模量、尺寸和数量以及位置等参数对支护结构变形和内力分布的影响.研究结果表明:相对于刚性环梁支撑,弹性环梁支撑处内力变化较小,环梁弹性模量和尺寸的改变只对基坑挖掘面以上支护结构变形和内力影响显著,而对挖掘面以下的支护结构变形和内力几乎没有影响.该研究成果为圆形基坑支护结构设计提供了理论依据和指导.

Thermal Stress Monitoring on Piston Rings by Real Time Holographic Interferometry

In this paper, real time holographic Interferometry (RTHI) technique was used to monitor the thermal stress on the piston rings. The piston rings holograms were recorded and the holographic plate replaced on the holder after development. The piston ring was subjected to thermal stress as it was illuminated by Laser beam acting as the object beam. This process led to generation of interferograms which were captured by a CCD camera at different temperatures. The captured interferograms were analyzed using atmosfringe version 3.3 software. From the analysis, the peak to valley (P-V) aberrations measured for each of the piston ring varied for the same temperature value. The P-V aberrations ranging from 0.0128λ to 1.2989λ were obtained. From this result, it was evident that the three rings on the piston had different unique structural characteristics due to their function.

圆形基坑极正交各向异性支护结构变形解析分析

考虑圆形深基坑支护结构轴向和环向配筋的差异,将支护结构简化为极正交各向异性圆柱薄壳,研究了分层土体中具有弹性支撑环梁约束的支护结构轴对称变形和内力特征.首先,将弹性支撑环梁的约束解除,代之以沿环向分布的未知集中力,基于弹性环梁和圆柱壳的边界条件和变形协调条件,得到了分层土体中具有弹性支撑环梁支护结构轴对称变形的解析解.其次,以上海地区某一圆形深基坑支护结构为例,揭示了支护结构环向和纵向弹性模量、环梁刚度、土体重度和静止土压力系数等因素对支护结构内力和变形的影响,结果表明:支护结构以环向承压为主,轴向弯曲为辅,故其环向刚度对径向位移的影响要明显大于其轴向刚度的影响,但材料参数对内力分布影响较弱;环梁刚度的增加可有效限制支护结构的变形,但会引起支护结构在支撑环梁处内力的显著增大;土层性质相差不大区域的支护结构可按均质土中支护结构进行分析,而土层性质有较大突变区域的支护结构分析则需考虑土层的分层效应.

Ring chromosome aberrations in human lymphocytes induced by 5-20 Gy carbon ion irradiation

In this paper,we study the biological response induced by heavy ions irradiation of high dose,human peripheral blood lymphocytes are irradiated in vitro by the carbon ions of LET=35 keV/μm,and the chromosome aberrations at absorbed doses of 0-20 Gy are analyzed by the calyculin A-induced premature chromosome condensation(PCC).The frequencies of PCC-rings at the stage of G2/M-phase increase steeply with radiation doses up to 20 Gy at a rate of 0.017 Gy^(-1).The G2-PCC index remains more than 5%up to 15 Gy,and 3%after 20 Gy,this is high enough to score a substantial number of chromosome spreads without dose-rate effect.The results show that the calyculin A-induced PCC technique is suitable for analyzing the chromosome damage induced by carbon ions irradiation of high dose.

电力隧道渗漏水成因分析及治理措施研究

电力隧道内电缆数量较多,电缆及其他电力设施对水非常敏感,如果积水淹没电缆(尤其是电缆接头部位),可能会造成事故和损失。文章详细分析了暗挖、盾构等结构形式隧道的渗漏水成因,对管片、环梁、沉降缝、墙体及管孔等部位渗漏水治理措施进行研究,提出了针对性的治理建议并进行了试点应用,为电力隧道渗漏水治理工作提供参考。

考虑环间接头影响的盾构隧道纵向变形简化解

为反映外荷载下盾构隧道相邻环间张开和错台,提出考虑环间接头影响的盾构隧道纵向变形简化解答。首先,引入纵向梁-弹簧模型模拟盾构隧道纵向受力变形,其中采用Timoshenko短梁考虑隧道环段变形,引入转动和剪切弹簧分别模拟环间接头转动与错台。其次,构建弹性地基上纵向梁-弹簧模型的有限差分方程,以解决环间接头-管环非连续变形求解问题,并推导外荷载下既有盾构隧道的纵向变形公式。最后,建立新建隧道上穿和下穿引起既有盾构隧道的纵向变形解答,并与新建隧道上、下穿越工程案例及现有理论方法对比验证。研究结果表明:所提方法预测的隧道位移与Timoshenko连续梁模型,协同变形模型和实测数据均具有较好的一致性,但所提方法得到的环间错台略低于Timoshenko梁模型和协同变形模型;所提方法可考虑环间接头的影响,得到的隧道位移曲线呈现既不光滑也不连续的特征,其中环段变形以刚体位移为主,而环间接头主要发生转动和错台;而基于现有理论所得盾构隧道纵向位移均为连续曲线,无法反映环间接头的真实转动与错台位移。

圆形深基坑环梁径向等效刚度系数研究

弹性支点法是我国现行规范推荐的深基坑支护结构计算方法。在弹性支点法基础上,针对圆形深基坑环梁作为支护桩弹性支点的刚度系数提出明确算法,达到更合理地计算支护结构内力和位移的目的。通过弹塑性力学厚壁圆筒理论,得到环梁径向位移公式,进而推导出环梁径向等效刚度系数和环梁换算截面的等效材料抗力计算公式。将径向等效刚度系数和等效材料抗力作为弹性支点的参数,计算支护结构内力和位移。采用此方法计算沈阳某圆形深基坑支护结构的内力和位移。结果表明:采用等效刚度系数的二维弹性支点法计算得到的支护结构的内力与位移,与现场监测数据比较吻合,比三维有限元计算结果更安全,比常规刚度系数计算结果更经济合理。

预制空腔模壳免支模免振捣构造柱-圈梁一体化技术研究

传统二次结构采用分层现浇方式进行施工,存在振捣质量难以保证、外观成型质量不稳定、入模口范围内密实度较差、施工效率低、成本高等问题。研究分别采用预制免拆模空腔模壳拼接成构造柱和圈梁,在构造柱和圈梁相交部位设置连接模壳,并在形成的构造柱和圈梁模壳内部顶升自密实混凝土,从而完成构造柱–圈梁一体化施工,解决了传统施工方法存在的上述问题,故该技术具有推广价值。

非均质环形谐振子结构性能分析方法

传统环形谐振子结构特性分析方法是基于均质弹性力学理论的,无法准确描述非均质材料力学特性对环形谐振子结构静、动态性能的影响规律。基于圆弧形结构的欧拉梁理论,根据非均质本构关系,运用Hamilton原理,提出一种非均质环形谐振子结构性能分析方法。利用非均质环形谐振子理论和布勃诺夫-伽辽金法,获得非均质环形谐振子静态弯曲问题和动态转动问题的理论解。然后,分析了材料的非均质力学特性对环形谐振子弯曲挠度、二阶弯曲角频率及进动系数的影响规律。典型非均质材料性能分析结果表明,传统方法对于二阶弯曲角频率计算误差达59%以上,而所提方法能够精确预测非均质谐振子结构的静、动态响应,计算出二阶弯曲角频率。

多轨道角动量模式谐振环形行波天线设计

为解决目前轨道角动量(OAM)天线难以在同一频率下多模工作的问题,推动OAM在无线通信领域的实际应用,设计、加工并测量了一种基于单层板的谐振环形行波天线,引入4个馈电探针将不同相位差的信号馈入行波天线。经仿真分析和实际测量,该天线可以在3 GHz上谐振并分别产生了携带有OAM模式l=0,l=±1,l=-2的涡旋电磁波束。该天线结构简单并且可以在同一频率下产生多种模式OAM,能够有效增加无线通信的信道容量,具有一定的理论意义和实用价值。

基于BIM技术模拟多向梁与环梁拼接节点的施工应用

多向梁与柱交接位置因受力复杂,各类型结构梁骨架相互交错,钢筋汇集,通常采用设置大直径钢筋混凝土环梁,解决大跨度多向梁结构节点搭接空间不够问题。环梁节点因钢筋、钢板等结构碰撞问题,拼接难度大。该文运用BIM数字技术,建立环梁与多向梁、柱之间拼接模型,制定节点拼接流程,计算各构件、钢筋加工尺寸,模拟现场拼装情况,确定各类钢筋安装顺序,一次性解决节点拼接碰撞等难题,保证施工质量、提高工效。实践证明,该技术实用先进,可以在类似工程中推广。

高功率VCSEL激光器光束发散角的测量方法

垂直腔面发射激光器(Vertical Cavity Surface Emitting Laser,简称VCSEL)由于其能发射出垂直于腔面光束的特性使得多个VCSEL激光器可以在同一片芯片上紧密集成,而不需要大量的空间;且VCSEL激光器使用共振腔的反射镜来增强光并放大,从而实现高效的光发射;通常情况下,VCSEL激光器的发光效率可以达到40至60之间,与传统的激光器相比,VCSEL激光器更容易实现高效率。由于VCSEL激光器的可集成性好、效率高等特点,使其广泛应用于3D感知、自动驾驶、光通信等领域。因此,VCSEL激光器的质量检测工作也显得越来越重要。随着VCSEL激光器进军高功率领域,其发光束的模式也经历了从基模变为高阶模的过程,光束已经从类高斯光束变为了类拉盖尔-高斯空心圆环光束。虽然传统的1/e^(2)、D86等算法在测量基模下的类高斯光束的发散角较为精确,但对于高阶模式下的类拉盖尔-高斯空心圆环光束,这些方法则出现了明显的误差。考虑到VCSEL激光器在自动驾驶等重要领域的广泛应用,其光束精确度的要求也随之提高。因此,本文采用了D4σ算法,针对类拉盖尔-高斯空心圆环光束进行发散角测量,与1/e^(2)、D86等传统算法进行了比较。结果显示,新方法在发散角测量准确度上最高提升了230。

既有办公建筑绿色改造关键技术

为有效利用城市土地资源并提高既有建筑使用价值,在既有建筑的基础上进行加层扩建,符合绿色低碳改造要求。某办公建筑在既有7层框架结构的基础上加层至18层,通过破除加层区域地下室底板,新增钢管桩并浇筑新的筏板基础,提高基础承载力。三桩承台与钢管桩采用环梁加固,确保新增筏板基础与既有基础能够共同工作。通过涂刷水泥基渗透结晶防水涂料和遇水膨胀止水胶,解决新旧混凝土结合面渗漏问题。通过采用改变荷载传递加层法、加大截面法及粘贴钢板法进行加固,确保改造后结构承载力和稳定性。

不同工况下液压插销升降系统定环梁建模策略及有限元分析

为了研究液压插销式升降系统定环梁在不同工况下结构强度,基于载荷传递路径分析、多点约束(MPC)方程,利用不同工况下建模策略开展定环梁有限元分析,并结合船级社规范开展校核验证。结果表明,升降系统的定环梁作业要根据载荷传递路径采取不同的建模策略;MPC方法相比于共节点的方法,克服了不同单元、不同结构交界面处节点不兼容的问题,能够有效的降低网格离散化过程中所消耗的时间,提高计算效率,节约计算资源;结构的校核需要考虑工况组合、应力集中系数、材料系数等综合因素后作出评定。研究成果可为不同工况下液压插销升降系统定环梁的分析校核提供参考。