Experimental study on the accumulative effect of multiple pulses on acceleration sensor

Intentional electromagnetic interference is a serious threat to the safety of electronic devices. Multiple electromagnetic pulses will be coupled and transmitted to electronic devices through the cables.Accumulative effects are generated, which make it easier for damage to occur in the electronic devices. In this article, the working principle of micro-silicon acceleration sensors is introduced. The accumulative effects of multiple pulses on acceleration sensors is studied by a large number of injection experiments.The accumulation trends of multiple pulses with different pulse numbers and intervals are analyzed. The damaged structures inside abnormal sensor amplifiers were observed via optical microscopy and scanning electron microscopy. The experimental results show that the accumulative effect is strengthened with increased pulse number or decreased pulse interval, and the threshold voltage for multiple pulses on the acceleration sensor decreases. The threshold voltage for a single pulse is 321.57 V. When the pulse interval is 1 μs and the pulse number is 5, the threshold voltage for multiple pulses is 163.42 V,which is reduced by 49.12% compared with a single pulse. These results provide a reference for the damage design of electromagnetic pulse weapons.

QUICK ASSESSMENT METHODOLOGY FOR RELIABILITY OF SOLDER JOINTS IN BALL GRID ARRAY(BGA)ASSEMBLY——PART Ⅱ:RELIABILITY EXPERIMENT AND NUMERICAL SIMULATION

In the present study,a facility,i.e.,a mechanical deflection system (MDS),was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly.It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days,but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests. Based on the MDS and ATC reliability experiments,the acceleration factors (AF) were obtained for different reliability testing conditions.Furthermore,by using the creep constitutive relation and fatigue life model developed in part I,a numerical approach was established for the purpose of virtual life prediction of solder joints. The simulation results were found to be in good agreement with the test results from the MDS.As a result,a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.

Theoretical Study of Similar Experimental Method for Durability of Concrete under Artifi cial Climate Environment

Based on the similarity theory,a new experimentalmethod named Similar ExperimentalMethod for Durability of Concrete（SEMDC）was established.The existing experimentalmethods for durability of concrete were summarized,and the merits and demerits of these experimentalmethods were analyzed.Major factors affecting the durability of concrete were found through literature review.These factors were analyzed and the similarity criteria were established according to the similarity theory,and then the SEMDC was established according to the rules of these criteria.The various influentialfactors of the experimentalmethod were analyzed and the merits and demerits of this new experimentalmethod were discussed.According to SEMDC,changing the geometry shrinkage ratio was the only way to accelerate the test in order to keep the experiment similar to the reality.There were few other parameters which need to be changed in SEMDC,making the test easy to be achieved.According to SEMDC,time shrinkage ratio was the square of geometric shrinkage ratio,so an appropriate increase of the geometric shrinkage ratio could accelerate the test.Finally,an example of experimentaldesign for durability of concrete was devised theoretically base on SEMDC theory.

Experimental and numerical studies on vibration characteristics of a railway embankment

In order to study the dynamic response of the rail embankment under different speeds and moving load of following vehicles,a model experiment with a ratio of 1:10 is established to test the time history of acceleration and the earth pressure of the embankment at various train speeds.Using the ABAQUS finite element calculation software,a train load is applied through the FORTRAN subroutine,thereby establishing a three-dimensional finite element model with the same size as the model experiment.The data and conclusions of the finite element method model are verified by the model experiment.The model also makes some supplements to the model experiment.The experimental results show that with the increase of speed,the peak acceleration and earth pressure of the embankment also increase.By analyzing the experimental data,it can also be found that the vertical acceleration of the embankment is much greater than the axial acceleration and the lateral acceleration.In addition,the elastic modulus of the soil and the sleeper pitch also have some influence on the acceleration.

Research on the Mechanism of Abrasive Particles Accelerated and a Cutting System of a Premixed Abrasive Jet

Forces acting on abrasive in the process of speeding up have been analyzed. Motion differential equation of abrasive in a pipeline and nozzle has been given, respectively. Mechanisms of abrasive particles accelerated in a premixed abrasive jet has been analyzed. The study shows that driven by high-pressure water, velocity of an abrasive is near to velocity of water in pipeline through the acceleration distance. In the taper section of a nozzle, water and abrasive particles are greatly accelerated at the same time. But velocity of an abrasive always lags behind velocity of water. A premixed abrasive jet cutting system has been introduced. The structure and working principles of the system have been given. The system is an assembly of abrasive screening and filling. By use of the premixed abrasive jet cutting system established, cutting experiments have been made to test the main parameters which influence the cutting performances such as working pressure, standoff and traverse velocity, and the nozzle diameter affecting cutting chink width.

Accelerated discovery of novel high-performance zinc-ion battery cathode materials by combining high-throughput screening and experiments

Aqueous zinc ion batteries(AZIBs)have attracted much attention in recent years due to their high safety,low cost,and decent electrochemical performance.However,the traditional electrodes development process requires tedious synthesis and testing procedures,which reduces the efficiency of developing highperformance battery devices.Here,we proposed a high-throughput screening strategy based on firstprinciples calculations to aid the experimental development of high-performance spinel cathode materials for AZIBs.We obtained 14 spinel materials from 12,047 Mn/Zn-O based materials by examining their structures and whether they satisfy the basic properties of electrodes.Then their band structures and density of states,open circuit voltage and volume expansion rate,ionic diffusion coefficient and energy barrier were further evaluated by first-principles calculations,resulting in five potential candidates.One of the promising candidates identified,Mg_(2)MnO_(4),was experimentally synthesized,characterized and integrated into an AZIB based cell to verify its performance as a cathode.The Mg_(2)MnO_(4)cathode exhibits excellent cycling stability,which is consistent with the theoretically predicted low volume expansion.Moreover,at high current density,the Mg_(2)MnO_(4)cathode still exhibits high reversible capacity and excellent rate performance,indicating that it is an excellent cathode material for AZIBs.Our work provides a new approach to accelerate the development of high-performance cathodes for AZIBs and other ion batteries.

Design,fabrication,and testing of an X-band 9-MeV standing-wave electron linear accelerator

In this study,an X-band standing-wave biperiodic linear accelerator was developed for medical radiotherapy that can accel-erate electrons to 9 MeV using a 2.4-MW klystron.The structure works atπ/2 mode and adopts magnetic coupling between cavities,generating the appropriate adjacent mode separation of 10 MHz.The accelerator is less than 600-mm long and constitutes four bunching cells and 29 normal cells.Geometry optimizations,full-scale radiofrequency(RF)simulations,and beam dynamics calculations were performed.The accelerator was fabricated and examined using a low-power RF test.The cold test results showed a good agreement with the simulation and actual measurement results.In the high-power RF test,the output beam current,energy spectrum,capture ratio,and spot size at the accelerator exit were measured.With the input power of 2.4 MW,the pulse current was 100 mA,and the output spot root-mean-square radius was approximately 0.5 mm.The output kinetic energy was 9.04 MeV with the spectral FWHM of 3.5%,demonstrating the good performance of this accelerator.

An <i>e</i>⁺<i>e</i>^-/<i>γγ</i>/<i>ep</i>Accelerator Complex at a Future Circular Collider

This is the second paper by the author describing versatile accelerator complexes that could be built at a Future Circular Collider (FCC) in order to produce e+e-, γγ and ep collisions. The facility described here features an ILC-based e+e- collider placed tangentially to the FCC tunnel. If the collider is positioned asymmetrically with respect to the FCC tunnel, electron (or positron) bunches could be accelerated by both linacs before they are brought into collision with the 50-TeV beams from the FCC proton storage ring (FCC-pp). The two linacs may also form a part of the injector chain for FCC-pp. The facility could be converted into a γγ collider or a source of multi-MW beams for fixed-target experiments.

Measurement of Acceleration Due to Gravity Using Arduino and Ultrasonic Sensor

In this study, a simple Arduino-based experiment was designed to examine the acceleration of the object during free fall and to calculate the value of “g” (acceleration due to gravity). Experimental data on the free fall of a plastic box through the air was gathered with the help of an ultrasonic distance sensor (HC-SR04). Readings were taken at different intervals during the fall to obtain distance time curves. Acceleration during the free fall was then determined by applying the standard kinematic equations. The shape of the distance-time graphs obtained from the experimental setup was in good agreement with the predicted graphs and the calculated values of g lie within the expected range. After repeated experiments, value of gravitational acceleration was found to be 9.805 m/s2. Hardware and software prepared for the experiment are sufficient to examine movement of ordinary objects during free fall, therefore the experiment can be easily settled in a laboratory for the purpose of learning and teaching.

超大颗粒肥水田气力深施加速器设计及参数优化

为解决水稻撒施追肥存在的肥料流失、利用率低及机械深施肥工作部件易堵塞、伤根等问题,该研究设计了一种用于水田深施追肥机的超大颗粒肥气力式加速器。该加速器利用双螺旋高压气流,在其与肥料上端构成的近封闭空间内加速超大颗粒肥,实现其高速射入泥壤,并可避免肥料颗粒与管壁碰撞;出口设置渐扩管扩散气流,可减轻对泥壤的冲击,提高施肥位置的稳定性。根据超大颗粒肥参数与加速器功能要求,确定了加速器的结构参数,并根据肥料入泥深度所需的射出速度,分析确定了加速器的工作参数。在此基础上,基于Fluent软件的六自由度重叠动网格建立了加速器仿真模型,以进口气流速度、螺旋角和加速管直径为试验因素,进行单因素仿真试验与三因素三水平Box Behnken组合仿真试验,研究各因素对肥料射出速度与气流扩散率的影响。多因素试验分析及响应面分析结果表明,加速器的最佳工作参数为进口气流速度47 m/s、加速管直径21 mm、螺旋进气口螺旋角43°。在此条件下进行台架验证试验,得到肥料射出速度均值为12.61 m/s,出口气流扩散率均值为85.5%,肥料入泥平均深度为4.7 cm,达到了水稻追肥要求。该研究可为超大颗粒肥水田气力深施追肥机设计提供参考。

精准温度控制半导体激光治疗仪及其可靠性分析

目的探究影响基于保偏光纤温度传感器的半导体激光治疗仪功率稳定输出的关键因素,探索实用化的激光治疗系统光电子器件可靠性分析方法。方法基于可靠性框图法,对系统光电子器件及其外围电路建立可靠度(RSL)、失效率(λSL)和平均寿命(LSL)分析模型,分析使用环境、运行时间(t)和工作温度(T)对系统运行可靠性的影响。基于加速寿命模型分别在室温大驱动电流(T=25℃、I=2.5 A)、高温工作电流(T=50℃、I=1.5 A)和高温大驱动电流(T=50℃、I=2.5 A)条件下,测试LSL与T、I以及T和I相互作用条件下的关系。结果仿真结果表明,λSL随T的增加而增加,LSL随T的增加而降低,RSL随T和t的增加而降低,在I为1.5 A、T为50℃的条件下,λSL、LSL、RSL估计值分别为5.229×10-51/h、17824.500 h、0.11418。实验结果显示,LSL分别为22873、17693和4780 h,实验测试结果与仿真结果吻合。结论基于本研究所提方法,可结合系统架构、设计方法、使用环境,分析计算出设备的λSL是否满足使用规范,进而预测出设备的RSL与LSL,为设计制造与临床使用提供数据支撑。

Xe^(23+)离子束轰击低温工况下的无氧铜表面解吸性能研究

强流重离子加速器运行时产生动态真空效应引起束流寿命缩短,需安装无氧铜束流准直器来降低该效应。为探究无氧铜材料在离子束轰击下的解吸性能,本工作设计并研制了满足低温工况的解吸率测试装置,在兰州重离子加速器国家实验室利用Xe^(23+)离子束完成了无氧铜温度在4.2 K、20 K、77 K和300 K,以及束流能量为0.58 MeV/u、0.96 MeV/u和1.3 MeV/u的在束试验。结果表明,离子束轰击无氧铜表面时解吸出最多的分子为H_(2),其次分别为H2O、CO、CO_(2)、Ar和O_(2);当温度为4.2 K、束流能量为0.58 MeV/u时无氧铜解吸出H2的比例为87.74%。在同一能量下,随着无氧铜表面温度的升高,解吸率呈增加趋势,能量为0.58 MeV/u时,4.2 K下无氧铜的解吸率仅为25 mol/ion,小于300 K时的600 mol/ion,表明温度越高其解吸产额越大。在同一温度下,随着束流能量的升高无氧铜表面解吸率增加,但增加趋势逐渐减缓,解吸产额趋向饱和。

食品加工条件对黑枸杞花青素稳定性的影响

黑枸杞富含花青素,花青素具有多种生理活性,然而其稳定性较差。文章研究了不同食品加工条件对黑枸杞花青素稳定性的影响,包括温度、pH值、光照、食品添加剂和基质等。结果表明,在20℃、pH3、避光条件下的黑枸杞花青素相对稳定,保存率分别为(89.74±5.54)%、(69.56±1.44)%、(57.85±0.50)%。H_(2)O_(2)、Na_(2)SO_(3)、苯甲酸钠和3种糖(葡萄糖、蔗糖、乳糖)均会大幅降低花青素的热稳定性(65℃,30 min)。除抗坏血酸外,草酸、酒石酸和柠檬酸增强花青素热稳定性的效果依次增大。在40℃加速贮存7 d后,草酸对花青素的稳定性仍然具有较好的效果。总之,黑枸杞花青素在食品加工过程中最好在低温、酸性和避光条件下贮存,而在选用食品基质和添加剂时也应该注意其对花青素稳定性的影响。该研究结果为黑枸杞花青素类食品的加工提供了理论依据。

基于NCS-ESKF算法的飞机姿态估计

传统误差状态卡尔曼滤波算法在无航向参考情况下进行飞机姿态估计时,由于其线性化不精确会导致误差较大。针对以上问题,提出了基于导航坐标系的误差状态卡尔曼滤波算法(NCS-ESKF),并设计了飞机姿态估计系统,开展了室内静态转台实验和通航飞机DA40机载飞行实验。实验结果表明,与3种传统算法相比,所提出的NCS-ESKF算法误差更小,其横滚角和俯仰角的平均绝对误差(MAE)仅为0.809°和0.934°;在机载飞行实验的滑跑阶段和飞行阶段,利用分段阈值法设定不同水平机动加速度阈值,其横滚角和俯仰角的MAE分别为0.954°和0.867°,有效提高了飞机姿态估计的准确性。NCS-ESKF算法能够有效减小估计误差,具有更高的飞机姿态估计性能,有助于提高通航飞机飞行控制的稳定性。

An improved bound on accelerated light dark matter

Light(sub-GeV)dark matter has gained increasing interest in terms of direct detection.Accelerated dark matter is a promising candidate that can generate detectable nuclear recoil energy within the sub-GeV range.Because of the large kinetic energy,its interactions with the nucleus are predominantly governed by inelastic scattering,including quasi-elastic and deep inelastic scattering.In this work,we calculated the inelastic effects in dark matter-Earth scattering mediated by a vector particle.Our analysis revealed that the impact of inelastic scattering relies on the mediator mass and the kinetic energy spectrum of dark matter.The results exhibited considerable disparity:the upper bounds of the exclusion limit for the spin-independent cross-section between accelerated dark matter and nuclei via a heavy mediator differ by several tens of times when inelastic scattering is considered.

基于Uni-app框架的高中物理实验App设计——以加速度传感器为例

基于Uni-app框架自主开发了高中物理实验App软件,详细阐述了基于手机传感器的App开发流程,并基于此实现了电梯加速度测量实验,讨论了气垫导轨测量重力加速度的实验过程,实验结果与理论值相符.与Phyphox软件进行对比发现:二者采集的实验数据吻合度较高.该自主软件的开发流程和实验过程描述,将为基于智能手机实验的App开发提供技术参考.

冲击试验机波形预测方法研究

在使用冲击试验机对产品进行考核时,其往往达不到规定脉冲波形的峰值加速度和脉宽,需要靠试验人员的经验以及多次重复试验进行调整。因此,为了在冲击试验前准确地预测冲击波形,节省调试时间和资源,提出了一种采用非线性回归模型对波形峰值加速度和脉宽进行预测的方法。首先,采用Mooney-Rivlin模型拟合了波形发生器超弹性本构参数,建立了冲击系统有限元模型,并进行了冲击试验,对有限元模型的准确性进行了验证;然后,采用有限元和正交实验法研究了波形发生器硬度、厚度、直径和冲击台跌落高度等参数对冲击波形的影响;最后,选用幂函数作为多元非线性回归的函数形式,并剔除了显著性较低因素项,建立了冲击波形峰值加速度和脉宽的预测模型,并通过冲击试验对预测模型的准确性进行了验证。研究结果表明:波形发生器的厚度和直径及其交互作用是影响冲击波形的主要因素;通过对比回归模型预测值与冲击试验数据,发现两者误差不超过10%,表明该冲击波形回归预测模型具有有效性。

对比三种单摆实验测量工具并利用Tracker软件探究锥摆运动

单摆测量重力加速度是大学物理实验中的一项基本内容,也是测量重力加速度的一种常规方法,实验中通常使用智能手机、多功能计时器、Tracker软件三种测量工具进行周期测量,利用固定单摆摆长直接计算和改变单摆摆长使用最小二乘法间接计算两种测量方法,对三种测量工具的精度进行了对比。实验结果表明,三种测量工具的精度由高到低依次是:Tracker软件、多功能计时器、智能手机。实验中,单摆周期往往受圆锥摆运动的影响而产生误差,使用Tracker软件分析得出:单摆做圆锥摆运动将导致所测重力加速度偏小。

原位格氏法合成甲基苯基二甲氧基硅烷

以氯苯(PhCl)、甲基三甲氧基硅烷(MTMS)和镁(Mg)为原料,甲基三氯硅烷(MTCS)为促进剂,通过原位格氏法一步制得甲基苯基二甲氧基硅烷[MePhSi(OMe)_(2)],并设计了4因素3水平的正交实验考察各工艺条件对产物收率的影响。结果表明,较佳的工艺条件为:Mg、PhCl、MTMS和MTCS的物质的量之比为1.0∶1.4∶2.5∶0.3,回流反应8 h,此时产物收率可达78%。

Experimental investigation of a pulse line ion accelerator in Lanzhou

In order to put the Pulse Line Ion Accelerator （PLIA） concept to its practical application, a small experimental platform was built. It was found that the actual axial electric field is smaller than the theoretical calculation, so the accelerated ions will enter into the deceleration zone before leaving the helix, which will seriously affect the acceleration process. Based on the improved parameters, the He＋ with 24 keV is accelerated to 55 keV, and the proof-of-principle experiment is completed on this platform.