Application of the monitoring and early warning system for internal solitary waves:Take the second natural gas hydrates production test in the South China Sea as an example

Internal solitary waves(ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ISWs was developed using technologies of double buoys monitoring, intelligent realtime data transmission, and automatic software identification. The system was applied to the second natural gas hydrates(NGHs) production test in the Shenhu Area, South China Sea(SCS) and successfully provided the early warning of ISWs for 173 days(from October 2019 to April 2020). The abrupt changes in the thrust force of the drilling platform under the attack of ISWs were consistent with the early warning information, proving the reliability of this system. A total of 93 ISWs were detected around the drilling platform. Most of them occurred during the spring tides in October–December 2019 and April 2020, while few of them occurred in winter. As suggested by the theoretical model, the full-depth structure of ISWs was a typical current profile of mode-1, and the velocities of wave-induced currents can reach 80 cm/s and30 cm/s, respectively, in the upper ocean and near the seabed. The ISWs may be primarily generated from the interactions between the topography and semidiurnal tides in the Luzon Strait, and then propagate westward to the drilling platform. This study could serve as an important reference for the early warning of ISWs for offshore engineering construction in the future.

Ecological risk assessment and early warning of heavy metal cumulation in the soils near the Luanchuan molybdenum polymetallic mine concentration area,Henan Province,central China

The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great significance to study the ecological risk and the accumulation trends of heavy metals in the soil of mining areas for scientific prevention and control of heavy metal pollution.Taking the Taowanbeigou River Basin in the mine concentration area as the research object,the ecological pollution risk and cumulative effect of heavy metals in the soil of the basin were studied by using the comprehensive pollution index method,potential ecological risk assessment method and geoaccumulation index method.On this basis,the cumulative exceeding years of specific heavy metals were predicted by using the early warning model.The comprehensive potential ecological risk of heavy metals in the soil near the Luanchuan mine concentration area is moderate,and the single element Cd is the main ecological risk factor,with a contribution rate of 53.6%.The overall cumulative degrees of Cu and Pb in the soil are“none-moderate”,Zn and Cd are moderate,Mo has reached an extremely strong cumulative level,Hg,As and Cr risks are not obvious,and the overall cumulative risks order is Mo>Cd>Zn>Cu>Pb>Hg.According to the current accumulation rate and taking the risk screening values for soil contamination of agricultural land as the reference standard,the locations over standard rates of Cu,Zn and Cd will exceed 78%in 90years,and the over standard rate of Pb will reach approximately 57%in 200 years.The cumulative exceeding standard periods of As,Cr and Hg are generally long,which basically indicates that these elements do not pose a significant potential threat to the ecological environment.Mining activities will accelerate the accumulation of heavy metals in soil.With the continuous development of mining activities,the potential pollution risk of heavy metals in the soil of mining areas will also increase.

基于PS-InSAR技术的晋城矿区地表形变监测及地质灾害风险预警

地表形变是一种严重的地质灾害现象,不仅严重影响灾害区居民的日常生活,而且会造成巨大的社会经济危害,尤其在采煤区。针对传统地表沉陷监测方法费时费力、无法获取地表沉降面状信息、难以进行地表沉陷灾害评估的不足,基于高分辨率SAR卫星影像,利用永久散射体合成孔径雷达干涉测量(PS-InSAR)技术对山西省晋城市晋城矿区2018年1月至2018年12月期间地表沉陷进行监测,分析获取了该地区地表连续形变情况,并利用该技术获取的海量PS点建立支持向量机(SVM)地质灾害风险评估预警模型,对晋城矿区周边居民点地质灾害风险进行了识别和预测。结果表明:晋城矿区10个煤矿及其周边区域存在较大的地表形变;晋城矿区平均LOS向年平均地表形变速率范围为-37~30.3 mm/a;PS-InSAR技术在晋城矿区地表形变监测中具有可行性,且可以实现矿区地质灾害风险综合识别和预警。

Drivers’ Reaction of Warning Messages in Work Zone Termination Areas with Left Turn

Work-zone crashes have always drawn public attention. A number of fatalities are recorded every year nationwide within work zone areas. Most existing countermeasures have been dedicated more to the advance warning areas, transition areas, and activity areas of work zone, than the termination areas, where drivers might play less attention to safety threats. In this study, the vehicle-to-vehicle communication based left turn warning system was applied at a work zone termination area, which is immediately followed by a T-intersection. The work-zone is located on the minor road side, while left turn vehicles will be appearing from the major street through the said T-intersection. A smart phone application was designed using Android coding system to provide several types of warning messages to drivers. Corresponding scenarios were designed in a driving simulator, and 20 subjects were recruited to participate in the simulation test followed by a questionnaire survey. The subjects received a warning message when driving to the termination area of a work zone on the coming left turn vehicles. Twenty test drivers’ driving speed, acceleration rates, and break reaction distance to the warning messages were studied in four different scenarios. Results show that the smartphone application has a great impact on driving behaviors, especially the female voice and the beep tone warning, which are recommended for possible field tests. Besides, the developed smartphone applications can be further updated for practical applications of similar needs.

An investigation of merging and diverging cars on a multi-lane road using a cellular automation model

In this paper, we have investigated two observed situations in a multi-lane road. The first one concerns a fast merging vehicle. The second situation is related to the case of a fast vehicle leaving the fastest lane back into the slowest lane and targeting a specific way out. We are interested in the relaxation time T, i.e., which is the time that the merging （diverging） vehicle spends before reaching the desired lane. Using analytical treatment and numerical simulations for the NaSch model, we have found two states, namely, the free state in which the merging （diverging） vehicle reaches the desired lane, and the trapped state in which T diverges. We have established phase diagrams for several values of the braking probability. In the second situation, we have shown that diverging from the fast lane targeting a specific way out is not a simple task. Even if the diverging vehicle is in the free phase, two different states can be distinguished. One is the critical state, in which the diverging car can probably reach the desired way out. The other is the safe state, in which the diverging car can surely reach the desired way out. In order to be in the safe state, we have found that the driver of the diverging car must know the critical distance （below which the way out will be out of his reach） in each lane. Furthermore, this critical distance depends on the density of cars, and it follows an exponential law.

Detection of Spatial, Temporal and Trend of Meteorological Drought Using Standardized Precipitation Index (SPI) and Effective Drought Index (EDI) in the Upper Tana River Basin, Kenya

Drought events across the world are increasingly becoming a critical problem owing to its negative effects on water resources. There is need to understand on-site drought characteristics for the purpose of planning mitigation measures. In this paper, meteorological drought episodes on spatial, temporal and trend domains were detected using Standardized Precipitation Index (SPI) and Effective Drought Index (EDI) in the upper Tana River basin. 41 years (1980-2016) monthly precipitation data from eight meteorological stations were used in the study. The SPI and EDI were used for reconstruction of the drought events and used to characterize the spatial, temporal and trend distribution of drought occurrence. Drought frequency was estimated as the ratio of a defined severity to its total number of events. The change in drought events was detected using a non-parametric man-Kendall trend test. The main drought conditions detected by SPI and EDI are severe drought, moderate drought, near normal, moderate wet, very wet and extremely wet conditions. From the results the average drought frequency between 1970 and 2010 for the south-eastern and north-western areas ranged from 12.16 to 14.93 and 3.82 to 6.63 percent respectively. The Mann-Kendall trend test show that drought trend increased in the south-eastern parts of the basin at 90% and 95% significant levels. However, there was no significant trend that was detected in the North-western areas. This is an indication that the south-eastern parts are more drought-prone areas compared to the North-western areas of the upper Tana River basin. Both the SPI and the EDI were effective in detecting the on-set of drought, description of the temporal variability, severity and spatial extent across the basin. It is recommended that the findings be adopted for decision making for drought-early warning systems in the river basin.

Risk monitoring and early-warning technology of coal mine production

This article was written according to the secudty information theory and the secudty cybernetics basic principle, for reducing the accident risk effectively and safeguarding the production safety in coal mine. First, each kind of risk characteristic has carried on the earnest analysis to the coal-mining production process. Then it proposed entire wrap technology system of the risk management and the risk monitoring early warning in the coal-mining production process, and developed the application software-coal mine risk monitoring and the early warning system which runs on the local area network. The coal-mining production risk monitoring and early warning technology system includes risk information gathering, risk identification and management, risk information transmission; saving and analysis, early warning prompt of accident risk, safety dynamic monitoring, and safety control countermeasure and so on. The article specifies implementation method and step of this technology system, and introduces application situations in cooperating mine enterprise, e.g. Xiezhuang coal mine. It may supply the risk management and the accident prevention work of each kind of mine reference.

An Intelligent Early Warning Method of Press-Assembly Quality Based on Outlier Data Detection and Linear Regression

Focusing on controlling the press-assembly quality of high-precision servo mechanism,an intelligent early warning method based on outlier data detection and linear regression is proposed.Linear regression is used to deal with the relationship between assembly quality and press-assembly process,then the mathematical model of displacement-force in press-assembly process is established and a qualified press-assembly force range is defined for assembly quality control.To preprocess the raw dataset of displacement-force in the press-assembly process,an improved local outlier factor based on area density and P weight(LAOPW)is designed to eliminate the outliers which will result in inaccuracy of the mathematical model.A weighted distance based on information entropy is used to measure distance,and the reachable distance is replaced with P weight.Experiments show that the detection efficiency of the algorithm is improved by 5.6 ms compared with the traditional local outlier factor(LOF)algorithm,and the detection accuracy is improved by about 2%compared with the local outlier factor based on area density(LAOF)algorithm.The application of LAOPW algorithm and the linear regression model shows that it can effectively carry out intelligent early warning of press-assembly quality of high precision servo mechanism.

基于SBAS-InSAR技术的松宜矿区形变监测与分析

矿区开采往往会带来地面沉降、地面塌陷等多种相关的地质环境问题,依靠传统的地面调查或仪器监测去收集矿区的地表形变信息效率不高且成本相对昂贵,InSAR技术的出现为此类有地表形变的地质灾害提供了更高效、更具性价比的监测方式。基于Sentinel-1A数据,利用SBAS-InSAR技术对松宜矿区进行地表形变监测,获取2017-03-12—2019-10-28地表形变结果,划定四个沉降区,即无沉降区、轻微沉降区、较大沉降区和严重沉降区,并着重分析6个沉降现象较为严重的子矿区逐年地表沉降速率及其变化趋势。结果表明,通过SBAS-InSAR技术解译的形变活跃范围与地面调查获取的成果有着较好的一致性,该技术可以为复杂山区中矿区地质灾害防治工作提供重点靶区,同时也为矿区地面沉降的监测预警研究提供新的思路。

Development and Application of On-line Wind Power Risk Assessment System

Because of the large-scale integration of wind power,the dynamic characteristics of power system have many uncertain effects.Based on deterministic analysis methods,traditional on-line security assessment system cannot quantitatively estimate the actual operating conditions of the power system for only considering the most serious and credible accidents.Therefore,the risk theory is introduced into an on-line security assessment system and then an on-line risk assessment system for wind power is designed and implemented by combining with the dynamic security assessment system.Based on multiple data integration,the wind power disturbance probability is available and the security assessment of the power grid can obtain security indices in different aspects.The operating risk index is an expectation of severity,computed by summing up all the products of the result probability and its severity.Analysis results are reported to the dispatchers in on-line environment,while the comprehensive weak links are automatically provided to the power dispatching center.The risk assessment system in operation can verify the reasonableness of the system.

基于数据驱动的快速路合流区加速车道长度的研究

设计长度合理的加速车道能有效地缓解快速路合流区频繁出现的交通瓶颈问题,因此采用数据驱动方法对快速路合流区的加速车道长度进行研究。利用无人机设备测取了快速路合流区的交通数据,从交通流特性及车辆汇入行为这两个角度对实测数据进行分析,得到了合流区车辆的驾驶行为;根据合流区交通流特点,对数据集进行聚类分析,使用生成对抗式网络训练不同合流区汇入行为车辆的跟驰换道模型,并与实测数据和SUMO仿真软件中内置模型进行对比分析;应用生成对抗式网络模型进行交通环境仿真,选取速度、交通密度、交通冲突率指标建立奖励评价函数,得出了加速车道长度设计的推荐值。研究结果表明:采用主线车辆提前减速和向内侧车道换道这两种手段,可实现协同换道避让匝道汇入的车辆;相比SUMO软件内置模型,生成对抗式网络模型更加贴近实际情况;仿真得出的单车道平行式加速车道长度分别在100、80、60 km/h情况下的推荐值为280、240、200 m。

基于新型智慧城市视角的地质灾害监测——以广州市为例

新型智慧城市建设为广州地质灾害监测提供了新机遇、新思路。笔者结合近年来地灾监测的科学研究和工程实践,从感知、调度、共治的角度浅谈对于广州地灾监测的一些思考。感知方面:广州市地貌结构复杂,北部丘陵台地作为地灾易发区,建议构建重点区域天-空-地三查体系,及时识别潜在风险源。预警调度:广州市地灾的发生与降雨有很强的时间相关性和空间耦合性,建议在广州市雨窝、降雨集中区构建精细化气象预警网格,提高监测预警精准度;针对地灾监测预警存在的重监测、轻预警现象,建议构建基于数据-知识双驱动的预警模型,实现高精度可解释的地灾预测建模;针对疑难边坡,建立专家研判系统,实现精准“把脉”,精准“治疗”。共建共治:加强跨部门跨层级合作,加强新建工程项目地灾评估,消减地灾存量,控制地灾增量。

铁路地质灾害勘察识别与监测预警

地质灾害对铁路建设、安全运营构成了极大威胁,“天空地”一体化综合勘察技术有效解决了地质灾害勘察识别难题。“天”基多源立体卫星遥感技术实现艰险复杂山区地质灾害的大范围精准判识,长时序InSAR与高精度GPS实现高陡岸坡的稳定性监测分析;“空”基真实感大场景、机载倾斜摄影和机载LiDAR扫描技术实现高植被覆盖区隐蔽性地质灾害判识;“地”基三维立体勘探技术获取岩土体结构、属性、参数;共同构建沟谷山地灾害链风险评价方案,为建设工程合理选址和工程设置提供依据。介绍地质灾害监测预警的方法、内容、技术和预警模型,对监测预警技术发展方向进行展望。

河北省涿州市“23.7”洪水模拟反演分析及思考

河北涿州“23.7”洪水影响大、损失重。为分析其原因,以及为灾后的恢复重建与今后的防洪治理等提供参考思路,建立了涿州市相关区域二维洪水数值仿真模型,对涿州市“23.7”洪水进行模拟反演及淹没影响对比分析。结果表明:除极端暴雨引发的洪水量级大外,涿州市特殊的地理位置,防洪工程薄弱,蓄滞洪区内建设用地大量增加,是本次洪水影响大、损失重的主要原因。涿州市今后的防洪治理及其蓄滞洪区内的土地开发建设,除参考相关区域的开发经验外,更应加强防洪工程建设、完善洪水防御体系、加强蓄滞洪区的建设与管理,强化洪水风险分析及实时预报预警,提高公众的洪水风险防范意识等。

考虑椭圆模型M_W≥5.5地震震源参数时域计算方法

为提高时效性,地震预警系统对震源的处理一般采用“点源”假定,不考虑震源尺度、破裂方向和震源区应力降,对震源参数简化处理使得预测地震动参数分布过于粗略,特别是对破坏性大震.本文应用日本地震(M_W≥5.5)强震动数据,考虑椭圆震源模型,提出了一种适用于中、大地震矩震级、拐角频率和应力降等震源参数时域计算方法,并分析了场地效应、地震动传播衰减、震源效应和滤波频带等因素对时域方法的影响.结果表明,该方法能利用P波信息快速获取震源能量释放过程,量化随破裂传播震源谱拐角频率、应力降和破裂面积的演化过程,为地震动预测提供更多重要的震源参数.

基于车路协同的快速路合流区可变限速控制方法

针对快速路合流区通行效率低的问题,利用车路协同环境下实时信息采集与交互技术,基于Gipps安全距离模型,对METANET模型进行改进;将动态安全距离融入可变限速控制中,建立起主线可变限速的控制方法和模型,引导匝道车辆利用主线可插间隙汇入,提高了快速路合流区的通行效率和匝道汇入的成功率;利用VISSIM与MATLAB联合搭建仿真控制环境,在不同流量下对所提出的控制策略进行仿真评估。研究结果表明:在中、高流量下,可变限速的控制策略使得速度分别提升了8.75%、 9.28%,密度分别降低了9.45%、 9.77%,行程时间分别降低了9.29%、 8.88%;延误分别降低了9.21%、 8.84%;证明了该可变限速控制策略能提升合流区通行效率,改善交通流运行状态。

基于GIS的灌区土壤投入品残留污染监测预警系统

为了解决工业发展导致的灌区土壤投入品残留污染问题,给出一种基于地理信息系统(geographic information system,GIS)的土壤污染监测预警系统。该系统结合VOC-PF1型传感器、STM32主控芯片和GSM通信模块,实现了高效的数据采集和通信功能。通过反距离加权(inverse distance weighted,IDW)插值法进行空间分析,并设立预警阈值,实现对灌区土壤投入品残留污染的实时监测和预警。实验结果表明:该系统的监测精度高达98%,监测时长最高为49 s,具有很高的实用性和效率。研究结果不仅为灌区土壤投入品残留污染监测提供了有效手段,也为环境保护和农业可持续发展提供有力支持。

点融合系统航班进场排序优化元胞自动机模型

针对点融合系统中航班调度问题,构建航班进场排序的二维元胞自动机模型,模拟先来先服务(first come first service, FCFS)和滑动窗口(sliding window, SDW)策略下的航班排序过程,对比不同策略下的终端区运行效率。实验结果表明:若都采用FCFS,使用中国民航航空器尾流重新分类标准(RECAT-CN)代替现行尾流间隔,进场航班流在点融合系统中的总运行时间减少了98 s,运行效率提升了4.3%;若都使用RECAT-CN间隔标准,采用SDW优化后的航班进场序列,较FCFS的总运行时间减少了193 s,运行效率提升了8.5%;点融合技术和RECAT-CN间隔标准可以实现终端区运行安全和效率的同步提升。

多无人车协同规划及突发情况下应急响应与恢复方法

面对环境突变、车辆故障等突发情况,传统集中式协同规划方法无法快速应急响应、实现系统冲突消解和有序恢复。针对以上问题,提出一种运动学约束下多无人车协同规划及突发情况下应急响应与恢复方法。首先,采用集中式搜索架构构建运动学约束下的协同路径规划模型,引入车身约束树以消解连续空间内多无人车碰撞。其次,为确保受突发情况影响的无人车能够安全快速停靠并降低对系统的干扰,提出一种基于预警区域的应急规划起始点选取方法,基于紧急事件发生时无人车状态生成的随机搜索树进行分层搜索,将随机搜索树、系统内部时空约束、无人车运动稳定性需求相结合,确保无人车能平稳过渡到应急停靠点。最后,在系统恢复过程中,针对不同无人车到达应急响应停靠点的时间差异,采用异步规划策略,将未受突发事件影响的车辆轨迹纳入协同规划的时空约束,最终生成应急响应后的恢复轨迹簇。仿真测试中,最优应急响应轨迹生成平均时长0.324 s,应急响应模块将规划成功率由28.7%提高到87.6%,异步模块在突发障碍物高达15个时将运行效率提升接近93%。

基于TTC冲突风险的加速车道合流标线设置方法

为了提高合流区域的安全性,分析了不同形式的交通设施对合流车辆的影响,研究了考虑速度离散性的加速车道安全合流设施设置方法。首先,以减小合流区的速度离散性为目的,基于车辆的实测加速与换道过程,分析了车辆在合流鼻后的运动过程。其次,基于驾驶员实际换道位置需求,构建了合流区禁止跨越同向车行道分界线(禁止跨越标线)长度计算模型,采用了重复仿真的方式确定最大值的要求。然后采用双向4车道作为仿真模型,对比分析了主线、匝道在不同流量、车速下的标线长度,总结了禁止跨越标线长度的演化规律。最后,基于实测数据搭建VISSIM仿真模型,以交通冲突为评价指标对设置效果进行了验证,分析在不同流量、主线速度、匝道速度组合下的禁止跨越标线设置必要性。结果表明:主线交通量增大,需设置的长度越长;主线与匝道速度差越大,标线长度越长;主线车速越大,标线长度越长,匝道车速越大,标线长度越短;主线流量在1级、2级上半段时的追尾与换道冲突明显减少,此时宜设置;在2级下半段之后时,换道冲突有所减少,但追尾冲突显著增加,需要结合最外侧车道车型比例等交通条件进行控制;在3级服务水平下,施画禁止跨越标线导致追尾冲突显著增加,换道冲突无显著变化,不建议设置。禁止跨越标线的设置能够进一步增加车辆加速空间,提高汇入速度,提升合流的安全性。