Joint Monitoring of Ground and Sky for Cereal Crops Based on Scatterometer Measurement and ASAR Images

The joint monitoring of the ground and sky for cereal crops based on microwave data has become a popular method for researches on earth surface objects. Focused on the sensitivity of backscatter from the scatterometer measurement and advanced synthetic aperture radar (ASAR) images to cereal parameters of rice, nine acquisitions, including rice parameters related eco-physiological variables and scattering coefficients, have been carried over the paddy field corresponding to rice growth stages. This paper analyzes the relationship between the corresponding backscatter to the cereal parameters based on the measurement at the interesting bands, polarizations, and incidence angels. Further, a modified water cloud model is built based on the ground measurement and advanced integrated equation model (AIEM), and then cereal parameters from ASAR images are retrieved and verified. The research results show that the sensitivity of backscatter to cereals from the sensor of the radar scatterometer could be helpful to build the retrieve model for synthetic aperture radar (SAR) images, which can achieve the scientific goals of the joint monitoring of ground and sky for cereal crops.

Comparison of Rectangular and Elliptical Control Region EWMA Schemes for Joint Quality Monitoring

The exponential weighted moving average technique used in process mean and variance monitoring charts was combined by Gan in 1997 and proposed two combined joint monitoring schemes one with rectangular control region and the other with elliptical control region. Performance of these two schemes may very depend on the shifts in mean or variance to be detected quickly. In this paper, performances of these two schemes are evaluated with respect to the average run length properties. The results reveal that elliptical scheme is little faster in detecting the shifts in process mean and increase in variance within a limit.

Continuous Damage Monitoring of a Thin Composite Structural with Mismatched Stiffener in a Combined Joint Using Fiber Bragg Grating under Tension and Three-Point Loading

A joint combining riveting and bonding is considered in terms of structural performance if the composite structure has a mismatched stiffener. The transfer loading is correlated with high performance aerospace joints to increase delamination resistance in the out-of-plane direction. However, combined joints (rivet/bonded) will create a bearing area that induces another potential damage source aside from secondary bending moment on the edge of the stiffener. Another problem is that the structure is difficult to be inspected by using conventional methods because of limited accessibility. The use of embedded fiber Bragg grating (FBG) technology in the structure as a strain sensor can potentially solve the problem in structures that have a stiffness mismatch. The FBG can be used to detect and characterize delamination before it reaches a critical stage. The model used to represent this problem is a thin composite stiffened skin under two load cases: tension and three-point bending. Finite element modeling using a traction versus separation theory is performed to determine the critical area on the specimen for placement of the FBG before manufacturing and testing. Experiments were presented to determine the distribution of load in a combined joint under both loading cases using ideal loads to create a secondary bending moment and bearing loads in the stiffness-mismatched structure. In this research, the FBG successfully detected and characterized the delamination caused in both loading cases. In addition, FBG can predict the delamination growth quantitatively. A spectrum graph of the FBG results can be used to replace the conventional mechanical graph in composite structural health monitoring in real applications.

Russia and China Signed a Statement on a Joint GNSS Monitoring and Assessment Service

At the recent,4th meeting of the Chinese-Russian Committee on Important Projects of Strategic Cooperation in the field of Satellite Navigation held in St.Petersburg,Russia.The China Academy of Aerospace Electronics Technology and FSUE Ts NIIMASS,the main research institute of Roscosmos State Corporation signed a statement on a new joint GNSS monitoring

Safety evaluation of replacement reinforcement quality in abutment contact zones of ultra-high arch dam in first impoundment period based on prototype monitoring

Reinforcement quality evaluation at the abutment is an important research direction. Prototype monitoring and theoretical derivation were integrated to study the replacement reinforcement quality in abutment contact zones of the Xiaowan ultra-high arch dam. The principles of monitoring layout and design are introduced in detail. Prototype monitoring shows that the increment of the interfacial compressive stress is much larger in the impoundment stage than in the regulating stage. The water pressure and time-effect are two main factors affeeting the interfacial stress. The time-effect is the key factor in the initial impoundment stage, and the water pressure is the key factor after impoundment. The contact properties are significantly improved by grouting. This study shows that there are three typical stages in the joint opening hydrographs, namely the compression stage, opening stage, and stable stage. There is a nonlinear relationship between the joint opening and temperature, which can be well described by the S-function. In conclusion, the reinforcement effect is satisfying, and the abutment is safe.

Analytical Research on Deformation Monitoring of Large Span Continuous Rigid Frame Bridge during Operation

Based on a large span continuous rigid frame bridge in Chongqing of China, the main pier vertical displacement and deviation, the bridge deck alignment and the expansion joint deformation are analytically researched during operation. Firstly, the monitoring content and method of the large span continuous rigid frame bridge are clearly stated. Secondly, by finite element software Midas Civil, the relevant deformation values of the bridge are calculated. Thirdly, in practice, the relevant deformation values of the bridge are measured. Finally, the measured values in practice are compared with the calculated ones by the finite element software Midas Civil, finding that the former is less than the latter, and it can be concluded that the bridge is basically in the normal working condition. In this paper, the analytical research on the deformation monitoring can provide the basis for similar bridges, which has good practical significance.

A Multi-scale Perspective on Drought Monitoring and Assessment for the Pearl River Basin

It is accepted that climate change has a great impact on water cycle and regional water balance,and thus it would change the formation and evolution conditions of drought in some degree. By using data at 42 meteorological stations of the Pearl River Basin,the Standardized Precipitation Evapotranspiration Index（ SPEI） at different time scales was calculated. Based on the SPEIs of 1- 12 months,a newly proposed index for drought--Joint Drought Index（ JDI） was established under the multi-scale perspective through the copula function. Since short-term SPEIs are essential for the identification of emerging droughts and long-term SPEIs are useful for prolonged droughts,the JDI,which integrates all the usefull informations of drought and can thus form an overall judgement,is superior than the single SPEI in drought monitoring. By the forcast evaluation system and comparison to the actual drought,the accuracy and effectiveness of JDI in drought monitoring were verified. In general,JDI can be used as a new ideal index for future drought monitoring and assessment. Additionly,we analyzed the spatio-temperal characteristics of drought across the Pearl River Basin using the JDI. The results indicate that mild drought was the most frequent drought occurred in the Pearl River Basin over the past half century,and moderate drought followed. Severe drought and extreme drought would appear occasionally while exceptional drought could hardly be found. A dry-wet-dry interdecadal variation pattern had been found from the 1960 s to the 2000 s. Since the 21 stcentury,an obvious trend toward drought can be observed in the whole basin,especially in the Xijiang subbasin,which,consequently,poses an increasing challenge for the water resource planning and management.

A 3D microseismic data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions and its application

Rock mass is a fractured porous medium usually subjected to complex geostress and fluid pressure simultaneously.Moreover,the properties of rock mass change in time and space due to mining-induced fractures.Therefore,it is always challenging to accurately measure rock mass properties.In this study,a three-dimensional(3D)microseismic(MS)data-driven damage model for jointed rock mass under hydro-mechanical coupling conditions is proposed.It is a 3D finite element model that takes seepage,damage and stress field effects into account jointly.Multiple factors(i.e.joints,water and microseismicity)are used to optimize the rock mass mechanical parameters at different scales.The model is applied in Shirengou iron mine to study the damage evolution of rock mass and assess the crown pillar stability during the transition from open-pit to underground mining.It is found that the damage pattern is mostly controlled by the structure,water and rock mass parameters.The damage pattern is evidently different from the two-dimensional result and is more consistent with the field observations.This difference is caused by the MS-derived damage acting on the rock mass.MS data are responsible for gradually correcting the damage zone,changing the direction in which it expands,and promoting it to evolve close to reality.For the crown pillar,the proposed model yields a more trustworthy safety factor.In order to guarantee the stability of the pillar,it is suggested to take waterproof and reinforcement measures in areas with a high degree of damage.

中国石化油藏地球物理二十年发展与思考

油藏地球物理技术是综合应用多种地球物理资料与油藏动静态信息进行复杂油藏精细表征和动态监测的跨学科技术,对于提高油藏的储量动用程度和提高采收率具有重要的意义,是当前地球物理技术的重要发展方向。系统回顾了中国石化油藏地球物理提出的背景和过去二十年的发展历程,梳理了油藏地球物理技术系列,总结了在油藏地球物理基础研究、井中地球物理技术、多尺度资料联合反演、地球物理约束确定性建模、时移地震剩余油气预测、地震地质工程一体化、微地震油藏监测等方面的技术创新和应用效果。面对中国油气田勘探开发的深层、深水、非常规及老油田(“两深一非一老”)形势和一体化、智能化、绿色化挑战,油藏地球物理在油气产业技术致胜阶段仍然大有可为,要持续创新油藏地球物理技术,井、震、动、模一体化联合和人工智能应用,构建高水平的油藏地球物理勘探开发一体化、地质工程一体化解决方案,支撑油藏全生命周期建设。

RFID电缆中间接头无线无源湿度监测

针对电缆中间接头受潮导致的运行故障问题,提出一种基于13.56 MHz RFID技术的无源湿度监测方法。该文利用HFSS建立传感器模型,调整天线匝距使天线达到理想状态,并对天线进行谐振匹配;然后研究传感器天线在水中的传输效果及存在金属屏蔽层时金属对天线性能的影响;最后将所设计的传感器放置于中间接头内部进行性能测试。结果表明:天线匝距为0.6 mm时传感器性能最佳;在天线外部增加47μH电容可实现13.56 MHz谐振匹配;传感器天线在水中的传输效果良好;加装金属屏蔽层可解决路径上金属对传感器信号传输的抑制作用;实际测量距离可达到8.2 cm、相对湿度测量误差最大为0.48%,最大波动幅度仅为0.3%,传感器长期处于高湿度环境仍能准确测量。该方法可实现电缆中间接头内部湿度的直接、快速及无源测量,对防止电缆受潮具有一定的参考意义。

多场耦合的冲击地压防治研究

研究煤岩体中断层、采空区、陷落柱等异常地质体的活化规律,对煤矿开采过程中可能发生的冲击地压、煤与瓦斯突出、突水等地质灾害进行及时预警,对回采过程中长壁工作面斜交正断层围岩应力场和位移场演变特征进行数值模拟,同时采用高精度微地震监测系统对其活化孕灾过程进行监测,将数值模拟结果和微震监测结果进行耦合分析。结果表明:断层和采空区附近的煤岩体属于高应力区,发生微震事件频次高,能量大,工作面推采至断层处顶板的位移变化更加显著。本文采用微地震监测和数值模拟耦合分析方法,能够有效地揭示煤岩中异常地质体活化过程,对冲击地压灾害进行预警,该方法为具有相同类型地质特点的工作面安全回采提供了参考。

基于物联网的高温热风炉膨胀节无线监测系统

针对某钢厂热风炉管道系统膨胀节设计了一套位移与泄漏的在线监测系统。传感器采用基于窄带物联网无线传输方式与监控平台连接,无须现场布线与外部供电,安装简便。对于无线传感器需在高温条件下工作,采取特殊散热设计,并通过Fluent软件仿真计算验证散热性能。最后在现场运行整个系统,实现了热风炉管道系统膨胀节在线监测,可为同类型高温膨胀节的无线监测方案设计作参考。

管网用膨胀节在线监测技术与应用

膨胀节是一个具有使用寿命的结构元件,当膨胀节的使用达到一定时间后,膨胀节就会发生失效。文章设计开发了一种基于无线传感网络的膨胀节在线监测系统,将物联网、大数据以及分布式软件等热点技术与膨胀节产品有机结合。通过试验测试及工程应用,能够有效地实时监测产品的运行工况,并进行预警及报警。

基于BCALoD的FPSO软刚臂系泊系统疲劳分析

针对软刚臂系泊系统铰节点在服役过程中出现的疲劳损伤问题,提出一种基于原型监测和局部密度双向聚类算法(Bidirectional Clustering Algorithm based on Local Density,BCALoD)的疲劳寿命计算方法。采用BCALoD算法对获得的船体六自由度进行工况分类,运用多体动力学将运动数据转算为受力时程,将其作为铰节点疲劳寿命分析的载荷谱。采用Abaqus软件建立各铰节点有限元模型以计算热点应力,结合Miner线性疲劳累积损伤理论和雨流计数方法计算疲劳寿命。进一步分析评估基于实测数据的铰节点疲劳设计指标,指出该FPSO软刚臂上铰节点的疲劳寿命不足以支持其完成服役,且各铰节点难以统一维护和更换。本研究可为在役软刚臂系泊系统的疲劳寿命计算提供一种新的载荷处理方法,为未来海洋平台的设计提供参考。

桥式起重机箱形梁异种钢焊接接头疲劳损伤的声发射表征

文中通过声发射技术对桥式起重机箱形梁Q345B/Q235B异种钢焊接接头疲劳损伤过程进行表征,发现了声发射特征参数变化取决于疲劳裂纹扩展不同阶段的特点,得以利用声发射动态监测桥式起重机循环载荷下的疲劳损伤状态,从而实现及早预警的目的。另外,通过对异种钢焊接接头焊缝和热影响区2种不同缺陷位置疲劳实验各阶段典型声发射信号的对比分析,获知热影响区比焊缝位置更易发生疲劳断裂,故箱形主梁在服役过程中应重点关注异种钢焊接接头热影响区位置并及早发现危险。

非侵入式综合能源系统源荷状态联合感知方法

区域(如园区或楼宇)综合能源系统(integrated energy system,IES)的多能流源荷协调运行与优化调控潜力评估分析对整体提升能源互联网的能源利用效率、促进可再生能源规模化发展具有重要意义。然而在实际工程中,普遍可获取的是用户IES与外部能源网络进行能量交换的端口处采集的粗粒度总量运行数据,据此往往难以对用户IES运行状态和特性进行准确分析,无法满足不断提高的IES运行调控需求。对此,以园区电/气/热IES为研究对象,提出基于耦合消元准则的IES非侵入式源荷设备状态联合感知方法,它仅利用在园区与外部电/气/热能源网络进行能量交换的端口处采集到的总量电/气/热运行数据及气象数据,辨识园区内部主要源荷设备的运行状态。总体上,基于IES内部各能源子系统间的耦合特性,按照气-电-热的顺序分别对每个子系统中主体设备的工作状态和(等效)运行功率进行非侵入式辨识。基于实测数据的实验结果表明,所提方法能够以“非侵入”的方式联合感知多能源荷设备的运行状态,精细化辨识园区IES内部主体设备的(等效)功率,具有较强的工程实用性,可为IES的仿真分析和运行决策提供细粒度大数据源。

不同节理起伏角的非贯通岩样拉伸剪切过程声发射演化特征

拉伸剪切破坏通常发生在深层现浇隧道施工过程中。本文利用自主研发的多功能岩石力学试验系统,对含有规则锯齿状节理的类岩试样进行直接拉伸剪切试验,研究节理起伏角度变化对拉伸剪切强度、温度和声发射的影响。结果表明,试样的峰值剪切强度随着节理起伏角的增大而降低,节理起伏角的增大导致岩桥更容易拉伸破坏,同时也使裂缝轮廓呈现出明显的阶梯状特征。在接近失效时,试样都产生了强烈的声发射信号,并产生了更多的裂纹,同时伴随能量耗散和温度降低。在三个试样的加载过程中,声发射b值呈现出先增大后减小的总体趋势,在接近峰值强度时急剧下降。根据RAAF值对裂缝进行分类,结果显示,在初始加载过程中,裂缝主要为纯拉伸类型。当试样接近失效时,剪切裂纹和复合裂纹的数量明显增加。

基于轨道雷达在某露天-地下联合开采边坡监测中的应用

为了深入探究轨道雷达在露天-地下联合开采边坡监测中的实际应用效果,选取云南大红山矿业露天采场-哈姆伯祖上废石场为研究区,根据其累计变形量圈出6个重点监测区域,结合矿山边坡雷达2024年2月1日—2024年2月29日的监测数据,对其累计变形量-时间曲线、变形速率-时间曲线、变形加速度-时间曲线变化进行研究。结果表明:地基合成孔径轨道式雷达在露天-地下联合开采边坡监测中起到关键性作用,该结果可为露天-地下联合边坡进行雷达监测工作提供参考。

基于联合时序InSAR技术的矿区沉降隐患区识别

针对目前单一InSAR解译技术方法在复杂地表形变解译中精度及可靠性有限的难点,提出了利用PS-InSAR(persist scatterers InSAR)、SBAS-InSAR(small base-line subsets InSAR)这2种时序InSAR技术联合进行山地矿区地面沉降隐患区圈划的方法。以湖北省宜都市松宜矿区为例,基于大样本理论,利用矿区内高精度的PS点形变结果,校正具有高空间覆盖率的SBAS-InSAR处理结果,从而进一步提高地表形变监测精度并增加形变靶区范围圈划的准确度。通过对比使用单一PS-InSAR技术和经过PS-SBAS联合方法处理后得到的典型形变点时序曲线及野外实地调查,验证了解译结果的可靠性。研究表明:联合时序InSAR技术可以提高地表沉降监测精度并增加地表变形靶区范围圈划的准确度,为类似山地矿区的地面沉降隐患监测与分析提供新的技术思路。