A dual-RPA based lateral flow strip for sensitive,on-site detection of CP4-EPSPS and Cry1Ab/Ac genes in genetically modified crops

Traditional transgenic detection methods require high test conditions and struggle to be both sensitive and efficient.In this study,a one-tube dual recombinase polymerase amplification(RPA)reaction system for CP4-EPSPS and Cry1Ab/Ac was proposed and combined with a lateral flow immunochromatographic assay,named“Dual-RPA-LFD”,to visualize the dual detection of genetically modified(GM)crops.In which,the herbicide tolerance gene CP4-EPSPS and the insect resistance gene Cry1Ab/Ac were selected as targets taking into account the current status of the most widespread application of insect resistance and herbicide tolerance traits and their stacked traits.Gradient diluted plasmids,transgenic standards,and actual samples were used as templates to conduct sensitivity,specificity,and practicality assays,respectively.The constructed method achieved the visual detection of plasmid at levels as low as 100 copies,demonstrating its high sensitivity.In addition,good applicability to transgenic samples was observed,with no cross-interference between two test lines and no influence from other genes.In conclusion,this strategy achieved the expected purpose of simultaneous detection of the two popular targets in GM crops within 20 min at 37°C in a rapid,equipmentfree field manner,providing a new alternative for rapid screening for transgenic assays in the field.

A rapid on-site calibration method for measuring dynamic envelope curve of high-speed trains

Dynamic envelope curve is a significant parameter to assess the running safety of high-speed trains.Up to now the method based on binocular stereo vision is the only way available to measure the dynamic envelope curve of a train,the speed of which is over200km/h.Nevertheless the method has two limitations,one is large field-〇f-view(FO V),the other is calibration time.Hence portable calibration equipment,easy-t〇-build target and rapid calibration algorithm are required to complete the calibration.In this paper,a new rapid on-site calibration method with large FOV based on binocular stereo vision is proposed.To address these issues,a light target has been designed,the rail coordinate system(RCS)is represented by40fixed retroreflective points on the target,and they are utilized to calibrate the parameters of two cameras.In addition,two cameras merely capture a single image of the target simultaneously,and the intrinsic and extrinsic parameters of the cameras can be calculated rapidly.To testify the proposed method,the experiments have been conducted and the results reveal that the accuracy can reach+1mm,which can meet the measurement requirement.

On-Site Calibration Method of Dosimeter Based on X-Ray Source

The real-time monitoring of environmental radiation dose for nuclear fa-cilities is an important part of safety, in order to guarantee the accuracy of the monitoring results regular calibration is necessary. Around nuclear facilities there are so many environmental dosimeters installed dispers-edly, because of its huge quantity, widely distributed, and in real-time monitoring state;it will cost lots of manpower and finance if it were tak-en to calibrate on standard laboratory;what’s more it will make the en-vironment out of control. To solve the problem of the measurement ac-curacy of the stationary gamma radiation dosimeter, an on-site calibra-tion method is proposed. The radioactive source is X-ray spectrum, and the dose reference instrument which has been calibrated by the national standard laboratory is a high pressure ionization. On-site calibration is divided into two parts;firstly the energy response experiment of dosim-eter for high and low energy is done in the laboratory, and the energy response curve is obtained combining with Monte Carlo simulation;sec-ondly experiment is carried out in the field of the measuring dosimeter, and the substitution method to calibrate the dosimeter is used;finally the calibration coefficient is gotten through energy curve correction. In order to verify the accuracy of on-site calibration method, the calibrated dosimeter is test in the standard laboratory and the error is 3.4%. The re-sult shows that the on-site calibration method using X-ray is feasible, and it can improves the accuracy of the measurement results of the stationary γ-ray instrument;what’s more important is that it has great reference value for the radiation safety management and radiation environment evaluation.

结合GUM和MCM的R-Test在机标定不确定度评定方法

R-Test因其高精度、操作便捷等的优点而被广泛应用于五轴数控机床转动轴误差测量,但其测量精度受其标定不确定度的影响。针对原有通用的评定方法不能对接触式R-Test标定不确定度进行准确评定,基于接触式R-Test标定原理,提出一种结合GUM和MCM的在机标定不确定度评定方法,首先分析了不确定度的影响因素并采用变参数方法确定了其灵敏度系数,然后根据测量不确定度导则(GUM)计算传感器位置的标准不确定度分量,最后采用蒙特卡洛方法(MCM)实现对标定方法最终的不确定度评定。通过具体的评定实例,与独立使用GUM的评定结果进行对比,验证了该方法具有更高的评定精度。

Integration of Tracer Test Data to Refine Geostatistical Hydraulic Conductivity Fields Using Sequential Self-Calibration Method

On the basis of local measurements of hydraulic conductivity, geostatistical methods have been found to be useful in heterogeneity characterization of a hydraulic conductivity field on a regional scale. However, the methods are not suited to directly integrate dynamic production data, such as, hydraulic head and solute concentration, into the study of conductivity distribution. These data, which record the flow and transport processes in the medium, are closely related to the spatial distribution of hydraulic conductivity. In this study, a three-dimensional gradient-based inverse method--the sequential self-calibration （SSC） method--is developed to calibrate a hydraulic conductivity field, initially generated by a geostatistical simulation method, conditioned on tracer test results. The SSC method can honor both local hydraulic conductivity measurements and tracer test data. The mismatch between the simulated hydraulic conductivity field and the reference true one, measured by its mean square error （MSE）, is reduced through the SSC conditional study. In comparison with the unconditional results, the SSC conditional study creates the mean breakthrough curve much closer to the reference true curve, and significantly reduces the prediction uncertainty of the solute transport in the observed locations. Further, the reduction of uncertainty is spatially dependent, which indicates that good locations, geological structure, and boundary conditions will affect the efficiency of the SSC study results.

New Explorations of Laboratory and On-site Testing of Broadband Seismographs in China

According to different testing purposes, methods and available environmental conditions, the seismograph testing can be divided into laboratory and on-site testing, respectively. The testing of the seismograph's key parameters and other concerning technical specifications are well described in guide documents(China Earthquake Administration, 2017). This includes seismometer sensitivity, linearity and clip levels based on the shake table test, as well as the seismometer natural period, damping constant based on electrical calibration(Wang Guangfu,1986; Ple?inger A.,1993) and instrumental self-noise collocation estimation(Holcomb L.G., 1989; Sleeman R. et al., 2006). However, with the development of seismic observation technology, many new requirements for the performance evaluation of seismographs have been put forward, and new testing items and methods have emerged.

Calibration of Four Nonlinear Failure Envelopes from Triaxial Test Data and Influence of Nonlinearity on Geotechnical Computations

It is now recognized that many geomaterials have nonlinear failure envelopes. This non-linearity is most marked at lower stress levels, the failure envelope being of quasi-parabolic shape. It is not easy to calibrate these nonlinear failure envelopes from triaxial test data. Currently only the power-type failure envelope has been studied with an established formal procedure for its determination from triaxial test data. In this paper, a simplified procedure is evolved for the development of four different types of nonlinear envelopes. These are of invaluable assistance in the evaluation of true factors of safety in problems of slope stability and correct computation of lateral earth pressure and bearing capacity. The use of the Mohr-Coulomb failure envelopes leads to an overestimation of the factors of safety and other geotechnical quantities.

An Experience of On-site PD Testing for Condition Monitoring of an 11 kV PILC Cable Insulation System

A cable circuit of a substation in the United Kingdom showed high level of PD activities during a survey using hand hold PD testing equipment. The authors were invited to carry out on-site PD testing experiment to further diagnose and locate the potential problem of the cable system. This paper presents the experience of the present authors carrying out the cable test. Following a brief introduction to the experiment equipments and physical connections, the paper analyses the data collected from the testing, including PD pulse shape analysis, frequency spectrum analysis and phase resolved PD pattern analysis. Associated with PD propagation direction identification, PD source diagnosis and localisation was made. Four different types of sensors, which were adapted during the testing, are shown to have different frequency bandwidths and performed differently. Aider comparing the parameters of the sensor and the PD signals detected by individual sensor, optimal PD monitoring bandwidth for cable system is suggested.

Calibration Method of Capacitive Soil Moisture Sensor

Soil properties and water content vary from place to place. The calibration method based on capacitive soil moisture and humidity sensor is carried out. The sensor readings are compared with the mass water content measured by the oven dried method,and the calibration formula of sensor reading and mass moisture content is established.Results show that the sensor reading has a good linear relationship with the mass water content measured by the oven dried method,and has high precision. It can calibrate the mass moisture content of the data obtained from the moisture migration test in the soil column.

Field measurements for calibration of simplified models of the stiffening effect of infill masonry walls in high-rise RC framed and shear-wall buildings

As a type of nonstructural component, infill walls play a significant role in the seismic behavior of high-rise buildings. However, the stiffness of the infill wall is generally either ignored or considered by simplified empirical criteria that lead to a period shortening. The difference can be greatly decreased by using a structural identification methodology. In this study, an ambient vibration test was performed on four on-site reinforced concrete high-rise buildings, and the design results were compared with the PKPM models using corresponding finite element(FE) models. A diagonal strut model was used to simulate the behavior of the infill wall, and the identified modal parameters measured from the on-site test were employed to calibrate the parameters of the diagonal strut in the FE models. The SAP2000 models with calibrated elastic modulus were used to evaluate the seismic response in the elastic state. Based on the load-displacement relationship of the infill wall, nonlinear dynamic analysis models were built in PERFORM-3 D and calibrated using the measured modal periods. The analysis results revealed that the structural performance under small/large earthquake records were both strengthened by infill walls, and the contribution of infill walls should be considered for better accuracy in the design process.

基于离散元法的面粉颗粒接触参数标定试验

为设计和优化面粉输送设备,应用离散元法对面粉进行准确地工程建模和分析,需要对其接触参数进行必要的标定。该研究依据颗粒缩放理论,用“Hertz-Mindlin with Johnson-Kendall-Roberts”接触模型表征面粉颗粒间黏性的影响,提出了一种基于静/动态休止角的接触参数标定方法。运用正交试验方法,对接触参数的敏感性和方差分析,表明面粉颗粒间的滚动摩擦系数、面粉颗粒与不锈钢表面间的静摩擦系数、表面能对静态休止角的影响极显著(P<0.01),并且多组接触参数都可以模拟出与试验相同的静态休止角。进一步研究表明,面粉颗粒与不锈钢表面间的静摩擦系数的合理取值范围为0.2~0.4。通过2种填充率、4种转速下基于动态休止角的参数标定,将其中与试验最为吻合的一组参数作为标定结果,其值如下:面粉颗粒之间恢复系数为0.6、面粉颗粒之间静摩擦系数为0.2、面粉颗粒之间滚动摩擦系数为0.1、面粉颗粒与不锈钢容器表面之间恢复系数为0.6、面粉颗粒与不锈钢容器表面之间静摩擦系数为0.6、面粉颗粒与不锈钢容器表面之间滚动摩擦系数为0.5、表面能为0.12 J/m^(2)。使用该组参数对矩形容器中物料自由坍塌试验进行仿真,其结果与试验结果相符,验证了该标定方法的有效性。该研究提出的标定方法简单、易执行,对粉料输送设备的设计及优化具有一定的工程应用价值。

低速水下机器人水动力试验系统设计

针对低速水下机器人模型试验测取水动力特性的需求,设计一款满足相似理论要求的室内小型低速开口式直流水洞;利用Fluent软件仿真得到试验段各截面速度分布云图,选出满足试验条件的截面范围;搭建试验平台并进行流场标定,结果表明稳流段速度达到2 m/s,稳流段的流场均匀且稳定,范围大于200 mm×68 mm×300 mm,满足阻塞率不大于25%、试验段长度通常是模型长度3倍的要求,验证了仿真结果的正确性且满足预期水下机器人模型试验的要求。此试验系统适用于速度不大于2 m/s,模型长不大于200 mm,模型来流方向的横截面积不大于5000 mm^(2)的试验条件。

苹果颗粒离散元接触参数标定与仿真试验

为精准确定红富士、花牛和黄元帅苹果的接触参数,该研究基于离散元法对3种苹果颗粒的仿真模型进行接触参数标定试验。首先,创建3种苹果的离散元填充模型,并通过电子秤、万能试验机等试验设备,确定其本征参数。其次,通过碰撞弹跳试验、斜面滑移试验和斜面滚动试验,得到红富士、花牛和黄元帅苹果与亚克力板的碰撞恢复系数分别为0.473、0.432和0.466;与亚克力板的静摩擦系数分别为0.435、0.536和0.519;与亚克力板的滚动摩擦系数分别为0.007 7、0.013 8和0.008 8。最后,通过堆积角试验、最陡爬坡试验确定二次回归正交旋转组合试验,得到红富士、花牛和黄元帅同种苹果间的碰撞恢复系数分别为0.487、0.348和0.469;静摩擦系数分别为0.584、0.869和0.644;滚动摩擦系数分别为0.084、0.096和0.093。试验结果表明,红富士、花牛和黄元帅苹果仿真试验与物理试验的休止角相对误差分别为5.95%、6.55%、8.67%。研究结果可为苹果物理特性和低损采收技术研究提供理论依据和模型支撑。

基于正弦式波纹膜片的压差式FBG静力水准仪

为解决建筑物不均匀沉降长期、可靠监测的问题,基于连通器原理,推导了膜片半径r、刚度K、光纤自由段长度l、波长变化量Δλ_(B)等参数和沉降量的线性关系式。以此设计了带有正弦式波纹膜片的压差式光纤布拉格光栅(FBG)静力水准仪,并通过标定试验验证压差式FBG静力水准仪的传感性能。结果表明:此静力水准仪灵敏度不小于13.2 pm/mm,综合误差不大于3.26%,相关性系数均在0.99以上。该型静力水准仪传感性能满足工程结构沉降测量的要求,丰富了FBG静力水准仪的研究,具有理论和现实意义。

饱和砂土液化Finn模型的关键参数

以闽江中细砂层为对象,开展三因素三水平正交设计的小型振动台试验,定性探讨闽江砂土液化特性;同时基于Finn模型,在FLAC3D数值平台上对典型试验过程开展动力时程数值模拟。结果表明:Finn模型可有效模拟地震动作用下饱和砂土孔压的增长与有效应力的降低,能较为准确地反映饱和砂土的液化效应,Finn模型中的关键参数C_(1)、C_(2)对计算结果影响显著。以超孔压比峰值及超孔压比稳定值为指标,通过大量数值模拟结果与试验结果的对比,对上述关键参数进行标定,建议闽江饱和砂土液化Finn模型的关键参数取值为C_(1)=1.30、C_(2)=0.31。饱和砂土激振过程中呈现出轻微剪胀趋势,大致与液化现象同步出现。

100 V输入宽频带电压比例校验系统研究

提出一种基于数字采集装置的50 Hz~10 kHz电压比例校验系统,由电压比例变换和数字采集装置构成。数字采集装置采用了通道切换技术,极大提高数字采集装置测量比例误差的准确度。电压比例变换部分由级联型感应分压器、隔离互感器及高、低压精密电压跟随器构成。为了降低分布参数引起的附加误差,设计了采用双绞线结构的双级隔离互感器;该双级互感器在10 kHz范围内幅值误差不大于5×10^(-6),相位误差不超过10μrad。利用双封装运算放大器特性匹配特征,补偿电压跟随器电路的相位响应,显著提升了低压和高压复合型电压跟随器的相位特性,10 kHz范围内,跟随器的幅值误差不大于10×10^(-6),相位误差不大于20μrad。测量结果表明,校验系统具有较好的测量准确度,50 Hz时的测量偏差不大于1×10^(-6)和1μrad,10 kHz范围内,比值误差偏差不大于80×10^(-6),相位误差偏差不大于60μrad,可满足不同频率场景下的电压比例误差测量需求。

活动门试验中土压力盒标定方法

为确保活动门试验结果的准确性,根据试验填土深度的不同,对一批相同型号的电阻式土压力盒进行了垂直方向上的分级加载和卸载标定,并考虑标定装置内壁摩擦力影响,修正了作用在土压力盒上的有效加载和卸载应力。通过对加卸载过程进行离散元模拟,证明有效加载和卸应力修正方法较为合理。标定试验结果表明,加载过程中微应变量-有效应力曲线呈线性变化,可使用线性函数拟合;卸载过程中微应变量-有效应力曲线存在明显的滞后现象,且滞后程度随有效加载应力的增大而增大,可使用单指数曲线拟合。标定土压力盒后,开展了填土试验,结果表明土压力盒不宜在压力过小或填土深度过小时使用。

利用无人机有源标定仪开展天气雷达远场标定试验

文章针对天气雷达缺乏远场标定能力的现状,提出利用无人机有源标定仪开展天气雷达远场标定的方案。通过给出无人机有源标定仪开展天气雷达远场标定试验的测试项目与条件,完成了对雷达天线、发射通道和接收通道的标定测试,试验结果符合相关技术要求。后期将对标定仪做进一步改进和完善,以期更好地满足雷达标定业务需要。

电池挤压试验机校准现状及实际需求分析

围绕电池挤压试验机开展试验所涉及的量值,充分分析了电池安全试验标准的要求、试验设备的功能性能、试验机构的实际需求,以及目前涉及该设备的校准规范的不足,提出了制定电池挤压试验机校准规范的必要性,并进行了模拟试验,论证了校准工作的可行性,同时提出了制定该校准规范需进一步考虑和确认的问题。

舰载飞机着舰撞击载荷实测技术研究

针对国内飞机起落架载荷测量中普遍存在的静标动测问题,从理论和机理上分析了静标定的应变法实测动态载荷存在问题的原因。同时,考虑到舰载飞机因定点着舰方式遭受严重的动态载荷,重点研究了舰载飞机着舰撞击载荷的静标动测问题。通过动态落震试验模拟飞机着舰过程,根据测力平台的实测载荷分析,获取了应变法实测载荷精度受动态影响的程度,提出一种改进的惯性修正方法,即:通过落震试验数据辨识质量矩阵,通过辨识的质量矩阵和实测加速度修正应变法的实测载荷。试验结果表明,改进的惯性修正方法进一步提高了垂向载荷的测量精度,显著提高了航向和侧向载荷的实测精度。