Seismic force demands on acceleration-sensitive nonstructural components:a state-of-the-art review

Nonstructural components(NSCs)are parts,elements,and subsystems that are not part of the primary loadbearing system of building structures but are subject to seismic loading.Damage to NSCs may disrupt the functionality of buildings and result in significant economic losses,injuries,and casualties.In past decades,extensive studies have been conducted on the seismic performance and seismic design methods of NSCs.As the input for the seismic design of NSCs,floor response spectra(FRS)have attracted the attention of researchers worldwide.This paper presents a state-of-the-art review of FRS.Different methods for generating FRS are summarized and compared with those in current seismic design codes.A detailed review of the parameters influencing the FRS is presented.These parameters include the characteristics of ground motion excitation,supporting building and NSCs.The floor acceleration response and the FRS obtained from experimental studies and field observations during earthquakes are also discussed.Three RC frames are used in a case study to compare the peak floor acceleration(PFA)and FRS calculated from time history analyses(THA)with that generated using current seismic design codes and different methods in the literature.Major knowledge gaps are identified,including uncertainties associated with developing FRS,FRS generation methods for different types of buildings,the need for comprehensive studies on absolute acceleration,relative velocity,and relative displacement FRS,and the calibration of FRS by field observations during earthquakes.

Preparation and Performance of a Fluorine-Free and Alkali-Free Liquid Accelerator for Shotcrete

Based on aluminum sulfate,a fluorine-free and alkali-free liquid accelerator(FF-AF-A)was prepared in this study.The setting time and compressive strength of three cement types with different FF-AF-A dosages were fully investigated.The compatibility of the FF-AF-A with the superplasticizers were also investigated,and the early hydration behavior and morphology of the hydration products of reference cement paste with the FF-AF-A were explored by hydration heat,X-ray diffractometry(XRD),and scanning electron microscopy(SEM).Test results indicated that adding the FF-AF-A at 8 wt%of the cement weight resulted in 2 min 35 s initial setting time and 6 min 30 s final setting time.The 1-day compressive strength of the cement mortar with 8 wt%of FF-AF-A reached 13.5 MPa,which represents an increase of 35%as compared to the strength of cement mortar without the FF-AF-A,and the 28-day compressive strength ratio was 119%.In addition,the FF-AF-A also showed good compatibility with different superplasticizer dosages.The results show that,when the FF-AF-A was added to the cement paste,it promoted the formation of ettringite crystals due to the aluminum ions(Al^(3+))and sulfate ions(SO_(4)^(2-))reacted with gypsum in the cement,as well as promoted the hydration of tricalcium aluminate(C_(3)A)and tricalcium silicate(C3S)leading to the overall structure becomes more compact.As a consequence,the hydration heat rate of the cement sharply increased,the cement paste setting time is shortened,and the compressive strength of cement mortar is improved.

Algorithm of the Simulation Type Expert System for Accelerator Single-Freedom Nonlinear Components

For accelerator single-freedom nonlinear components,a general mathematicalmodel with its solution algorithm is developed,based on which a simulation type expertsystem can be built on IBM PC,automatically yielding any order approximate analyti-cal solutions.

Expert System for the Transport Operator of Accelerator Single-Freedom Nonlinear Components

An expert system by Arity Prolog is developed for the transport operator of accelera-tor single-freedom nonlinear components. It automatically yields any order transport operatorand its inverse transport operator for various accelerator single-freedom nonlinear components.As an example, the fifth order inverse transport operator derived by the expert system is given.

Expert System for Accelerator Single-Freedom Nonlinear Components

An expert system by Arity Prolog is developed for accelerator single-freedomnonlinear components.It automatically yields any order approximate analytical solu-tions for various accelerator single-freedom nonlinear components.As an example,theeighth order approximate analytical solution is derived by this expert system for a gen-eral accelerator single-freedom nonlinear component,showing that the design of the ex-pert system is successful.

Transport Operator of Accelerator Single-Freedom Nonlinear Components

For accelerator single-freedom nonlinear components,the general theory of nonlinear transportis developed,and the algorithm for the inverse transport operator is given,based on which an expert sys-tem can be built to automatically yield any order transport operator and its inverse transport operator forvarious accelerator single-freedom nonlinear components.

FPGA Accelerators for Computing Interatomic Potential-Based Molecular Dynamics Simulation for Gold Nanoparticles:Exploring Different Communication Protocols

Molecular Dynamics(MD)simulation for computing Interatomic Potential(IAP)is a very important High-Performance Computing(HPC)application.MD simulation on particles of experimental relevance takes huge computation time,despite using an expensive high-end server.Heterogeneous computing,a combination of the Field Programmable Gate Array(FPGA)and a computer,is proposed as a solution to compute MD simulation efficiently.In such heterogeneous computation,communication between FPGA and Computer is necessary.One such MD simulation,explained in the paper,is the(Artificial Neural Network)ANN-based IAP computation of gold(Au_(147)&Au_(309))nanoparticles.MD simulation calculates the forces between atoms and the total energy of the chemical system.This work proposes the novel design and implementation of an ANN IAP-based MD simulation for Au_(147)&Au_(309) using communication protocols,such as Universal Asynchronous Receiver-Transmitter(UART)and Ethernet,for communication between the FPGA and the host computer.To improve the latency of MD simulation through heterogeneous computing,Universal Asynchronous Receiver-Transmitter(UART)and Ethernet communication protocols were explored to conduct MD simulation of 50,000 cycles.In this study,computation times of 17.54 and 18.70 h were achieved with UART and Ethernet,respectively,compared to the conventional server time of 29 h for Au_(147) nanoparticles.The results pave the way for the development of a Lab-on-a-chip application.

贮后乙烯利处理对1-甲基环丙烯保鲜花牛苹果催熟品质的影响

目的研究乙烯利催熟对低温贮藏10个月、经不同浓度1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理的花牛苹果果实品质和香气成分的影响。方法以天水花牛苹果为试材,采用不同浓度1-MCP熏蒸处理(0、1、2μL/L)后,置(0±1)℃低温下贮藏10个月,研究乙烯利催熟处理对其感官品质(果实硬度、可溶性固形物、可滴定酸、呼吸速率和乙烯释放量)、挥发性香气物质成分等指标的影响。结果不同浓度乙烯利处理均使花牛苹果果实贮后呼吸强度、乙烯释放量增加,果实硬度、可滴定酸含量降低;乙烯利催熟后,果实香气有效恢复,贮后经1、3、5 mL/L乙烯利处理的果实常温货架10 d时,分别检测出70、87和81种香气成分,较同期不经乙烯利催熟果实分别增加16.7%、45.0%和35.0%,且3 mL/L乙烯利处理对0、1μL/L 1-MCP处理果实催熟效果最佳,5 ml/L乙烯利处理对2μL/L 1-MCP处理果实催熟效果最佳。结论贮后乙烯利催熟处理可加快经保鲜处理花牛苹果的后熟进程,促进果实香气成分的产生,提高其感官品质和食用价值。

花椒油和藤椒油加速氧化过程中风味品质变化

旨在为提高花椒油和藤椒油品质稳定性和预测其货架期提供参考,研究储存过程中花椒油和藤椒油风味品质变化。采用Schaal烘箱法探讨加速氧化过程中(0~35 d)花椒油和藤椒油的酸值、过氧化值、麻味物质及挥发性风味成分的变化。结果表明:加速氧化过程中花椒油和藤椒油的酸值(KOH)均满足国家限量标准(≤3 mg/g),而过氧化值分别在15 d和20 d时超出国家限量标准(≤0.25 g/100 g)。花椒油和藤椒油分别加速氧化10 d和15 d时麻味物质总量损失率分别为5.86%和10.42%,挥发性风味成分总量损失率分别为35.07%和70.01%;加速氧化结束时,花椒油和藤椒油中麻味物质总量和挥发性风味成分总量大幅减少,麻味物质总量损失率分别为37.15%和37.30%,挥发性风味成分总量损失率分别为82.03%和89.08%;对挥发性风味物质进行主成分分析(PCA)发现,未加速氧化的油与加速氧化后的油区分明显。花椒油和藤椒油在储存过程中麻味物质和香气成分存在着不同程度的损失,且长时间储存易氧化酸败,对产品风味品质影响较大。

卫星高压电子组件可靠性评估技术研究

可靠性是指产品在规定的条件下和规定时间内完成规定功能的能力。在航天系统,可靠性评估是型号产品研制过程中的关键工作,是决定产品能否稳定运行的重要指标之一。主要针对卫星高压电子组件小子样、长寿命的特点,以电推进系统中离子电推进的电源处理单元为例,结合故障模式和失效机理分析,实施加速寿命试验,根据试验数据开展卫星高压电子组件可靠性评估技术的研究。

空间挠性作动器的可靠性验证试验方法

为了对空间挠性作动器在轨运行的可靠性进行评估,针对作动器在轨工况复杂、小子样、长寿命的特点,给出了作动器可靠性验证试验方法。首先,在分析作动器结构组成及工作原理的基础上,确定了作动器可靠性特征量。然后,以寿命型可靠性试验为基本思路,针对挠性元件在轨疲劳断裂失效这一主要故障模式,根据在轨典型工况载荷数据进行疲劳试验载荷谱设计,采用试验载荷谱开展挠性元件加速疲劳寿命试验,基于试验结果给出作动器的可靠性评估结果。最后,以某型号空间挠性作动器为例,基于挠性元件加速疲劳试验进行可靠性试验验证,得到作动器可靠性评估结果。研究结果表明,该作动器可靠度满足指标要求,评估结果符合工程实际。运用所提出的可靠性验证试验方法,可为空间挠性作动器在轨运行可靠性的定量评估提供有效的技术途径,可为航天器运动机构的可靠性验证提供参考。

工业氟硅酸改性硫酸铝基无碱液体速凝剂性能的研究

以硫酸铝作为主料,复配三乙醇胺、碳酸锂等物料,制备无碱液体速凝剂,再将工业氟硅酸作为改性组分,考察了不同工业氟硅酸掺量下硫酸铝无碱速凝剂对P·O 42.5普通硅酸盐水泥的凝结时间、抗压强度性能的影响。采用XRD、SEM和TG-DTG分析探究试样水化产物的物相组成及微观形貌,进一步探讨了掺改性组分硫酸铝速凝剂的水泥水化反应进程及改性组分的作用机理。结果表明,工业氟硅酸掺入速凝剂中,能显著缩短水泥的凝结时间。当速凝剂中工业氟硅酸掺量为10%时,水泥凝结时间达到最小值,初凝和终凝时间分别为1.67 min和4.28 min。随着速凝剂中不同掺量工业氟硅酸的加入,砂浆的1 d抗压强度以及28 d抗压强度先增大后减小,抗压强度在工业氟硅酸掺量为6%时达到最大值,1 d和28 d强度分别为12.4 MPa和48.4 MPa。对比未掺入工业氟硅酸的速凝剂,加入工业氟硅酸后水泥浆体会消耗CH成更多针棒状AFt,且加快C_(3)S水化,形成C—S—H凝胶。但是,当工业氟硅酸掺量过量时,生成的CaF_(2)沉淀物会抑制水化反应,影响砂浆1 d的抗压强度形成。

基于FPGA的多路视频采集及AI加速

基于MES50HP开发板及PC主机实现了多源视频采集、拼接及AI协同处理的加速工作。所提出的系统可支持同时采集HDMI、网口、摄像头和光纤4路视频数据,视频采集拼接后,将缩放后存入双倍速率同步动态随机存储器(DDR)中,输出部分分为2路,其中1路数据用于HDMI回环输出,另外1路通过PCIE传至PC主机用于结果显示,并在PC端读取PCIE传回的数据并显示目标检测结果,其中视频采集和目标识别加速部分主要由2块MES50HP开发板构成。本系统在FPGA上实现了卷积加速器,卷积加速器计算完神经网络的一层后再通过PCIE传至主机进行结果显示,卷积计算与图像采集进行深度融合,具有实时、低成本的特点,可广泛应用于边缘计算等领域。实验结果表明:针对红绿灯数据集,该方法在低成本PC主机上实现的最大平均精度均值(mAP)为0.746,最高帧率达45帧。

基于CESMD数据的楼面加速度放大系数研究

为了合理地估算楼面加速度放大系数(f),确定施加在加速度敏感型非结构构件上的地震作用力,基于CESMD地震数据库中73座混凝土结构的地面和楼面加速度实测数据,给出不同高度类型、场地类别以及地震强度的混凝土结构f抛物线参数值与房屋顶层f的取值建议,采用台湾集集地震实测数据验证基于抛物线模型的f正确性。研究表明,多层和高层混凝土结构,随着输入地面峰值加速度的增大,不同场地类别相差85%和43%,f与场地类别相关,以往研究并未指出,所拟合f的抛物线曲线可较好地反映出混凝土结构实测f的分布特点。该研究为加速度敏感型非结构构件的设计提供了f的取值建议。

进口红花籽油氧化过程中挥发性成分变化分析

以新疆口岸进口红花籽为实验材料,经低温物理压榨获得冷榨红花籽油,采用顶空固相微萃取-气相色谱-质谱(HS-SPME-GC-MS)法分析红花籽油加速氧化期间挥发性成分动态变化。结果表明:新鲜红花籽油中以己醇、己醛、己酸等C6化合物为特征挥发性成分,随着氧化程度的加深,不饱和醛的含量及种类逐渐增加。结合相对气味活度值(Relative Odor Activity Value,ROAV)发现,E,E-2,4-癸二烯醛、E,E-2,4-壬二烯醛、E-2-辛烯醛、E-2-庚烯醛等不饱和醛是氧化红花籽油的特征风味物质,可以作为进口红花籽油品质判定的新指标。主成分分析表明,不同氧化程度的红花籽油可以通过关键挥发性成分得到很好的区分,以期为进口红花籽油的品质判定和品名鉴定提供技术支持。

轨道车辆制动产品橡胶件加速寿命试验研究

根据橡胶件在制动产品中的实际工作状态分析了橡胶件的失效机理,确定了影响使用寿命的特征参数,结合橡胶样件的阿累尼乌斯模型建立某种配方橡胶件的加速寿命模型,研究了一定应力下的高温加速寿命试验方法,并以空重阀橡胶件为例,进行了高温加速寿命试验。研究结果表明,高温加速因子的确定方法具有可操作性,能有效验证制动产品橡胶件使用寿命。

元器件恒定加速度试验工装分析与改进

在军事工业领域,多数环境中都有恒定加速度的存在。为了确定离心力对器件的影响,评估元器件是否存在结构或机械缺陷,军工单位在元器件可靠性筛选环节中加入了恒定加速度试验。由于器件内部结构复杂,芯片、引线、衬底、封装壳体等十分紧凑,如何设计合适的恒定加速度试验固定夹具,保证筛选过程中既能发现结构缺陷又不损伤元器件,已经成为夹具设计中的重要考虑因素。文章针对恒定加速度试验中几种固定方式存在的问题,通过优化夹具设计和试验验证,提出了一种新型的恒定加速度试验工装系统,该工装能有效提升检测效率,并保证了试验过程中产品外观不受影响。

ACCELERATED DISCOVERY AND PROFILING OF PHYSIOLOGICALLY ACTIVE COMPONENTS IN COMPLEX SAMPLES BY HPTLC-EDA-HRMS

On the one hand,the separation of thousands of compounds in a complex extract is thrilling,but may be still be separated unsatisfactorily.Hence,the question arises where to stop in high-sophisticated separation science?Which technical effort is economically justifiable in routine?On the other hand,the separation itself does not imply an effect-directed answer to questions such

基于脉冲数据重构的高速铁路关键零部件检测算法

对运行中的高速铁路(简称“高铁”)关键零部件进行快速准确定位是高铁故障诊断的基础之一。然而,利用普通工业相机对运行中的高铁进行数据采集会存在运动模糊或关键零部件丢失问题,而利用超高速脉冲相机采集的数据进行目标检测模型训练又会存在数据难以标注以及模型难以训练等问题。对此,文章提出一种基于脉冲数据重构的高铁关键零部件检测方法。其首先基于脉冲触发原理,利用脉冲间隔还原不同位置的光强,并通过计算全局光强调整局部光强,且对调整后的结果进行滤波与局部增强处理,重构出高清分辨率灰度图像;在此基础上,对重构后的灰度图像进行数据清洗与标注,并利用标注后的数据进行高铁关键零部件检测模型训练;最后,基于TensorRT对训练后的模型进行加速。试验结果表明,经过加速后的高铁关键零部件目标检测模型能够实现98.7%的平均精确度以及平均3.5 ms的单帧推理速度,为算法的工程化应用奠定基础。

基岩场地强地面运动加速度反应谱统计特征

根据强地面运动加速度数据,采用经验地震动衰减关系公式,利用回归统计分析的方法,研究竖向和水平向加速度反应谱的关系。统计分析结果表明竖向地震动与水平向地震动的关系比较复杂,不同周期竖向与水平向加速度反应谱的比值受震级和震中距的影响不同。用水平向加速度反应谱按简单的系数折算成竖向加速度反应谱的做法应慎重。