Hydrochemical Constraints on the Flowing Paths of Groundwater in Limestone Reservoirs beneath the Pingdingshan Coalfield in North China

The karst groundwater of Cambrian limestone may become an important water source for industry and agriculture in the Pingdingshan area,and is also a potential threat to mining safety.Therefore,to find out the origin,flow paths,and hydrogeochemical processes of karst groundwater beneath the Pingdingshan coalfield,a total of 16 water samples were collected.Our findings confirmed that the karst groundwater is mainly recharged by precipitation.The precipitation can directly supply the deep aquifer of the karst water system through the southwest limestone outcrops,and this area mostly includes the southern part of mines No.11,No.9,and the hidden outcrops in the southern part of mine No.2.What is more,the areas adjacent to the synclinal axis,including mines No.10,No.12,and No.8,may be the main discharge areas.A mixing model of^(87)Sr/^(86)Sr and Sr showed that in the southwest Pingdingshan coalfield,the proportion of precipitation decreased gradually from the recharge area to the discharge area,ranging from 89.1%to 17.1%.Besides,the northeast Pingdingshan coalfield is another recharge area for the whole karst system,thus,the infiltrating groundwater will indirectly supply the deep aquifer through Quaternary deposition near the mine No.13.Our research results can provide theoretical support for the prevention and control of groundwater disasters and the development and utilization of regional groundwater resources in the coalfield in Northern China.

A Study on Optimizing the Double-Spine Type Flow Path Design for the Overhead Transportation System Using Tabu Search Algorithm

Optimizing Flow Path Design(FPD)is a popular research area in transportation system design,but its application to Overhead Transportation Systems(OTSs)has been limited.This study focuses on optimizing a double-spine flow path design for OTSs with 10 stations by minimizing the total travel distance for both loaded and empty flows.We employ transportation methods,specifically the North-West Corner and Stepping-Stone methods,to determine empty vehicle travel flows.Additionally,the Tabu Search(TS)algorithm is applied to branch the 10 stations into two main layout branches.The results obtained from our proposed method demonstrate a reduction in the objective function value compared to the initial feasible solution.Furthermore,we explore howchanges in the parameters of the TS algorithm affect the optimal result.We validate the feasibility of our approach by comparing it with relevant literature and conducting additional tests on layouts with 20 and 30 stations.

The Full Flowpath Analysis of a Hypersonic Vehicle

A numerical study has been carried out to investigate the full flow path and aerodynamic characteristics of a hypersonic vehicle at a 7.0 free stream Mach number. Results indicate that the inlet started and unstarted operations have remarkable effects on the flow pattern of the full flow path. When the inlet operates in a started mode, the transverse pressure gradient generated by the forebody alters the air captured characteristics and the entering flow quality of the inlet. Furthermore, the expansion process of the nozzle jet flow is obviously affected by the external flow field around the afterbody with the cross section shape transiting from a near rectangle at the exit of the nozzle to a near triangle at the tail of the vehicle. When the inlet operates in an unstarted mode, the aerodynamic instability can be observed in the full flow path of the vehicle. Due to the oscillation of the external compressed shock wave and nozzle jet flow, the aerodynamic characteristics of the vehicle vary periodically with the lift-drag ratio changing from 0.25 to 2.09. Finally, by comparing to the experimental data, the reliability of the CFD is verified.

Hydrogeochemistry and Water Quality Evaluation along the Flow Path in the Unconfined Aquifer of the Düzce Plain, North-western Turkey

The Diizce Plain has a multi-aquifer system, which consists of a near surface unconfined aquifer, along with first and second deeper confined aquifers. Hydrochemical evolution and water quality are related to infiltration of the precipitation, recharge from the formations surrounding the plain, flow path of groundwater and the relationship between surface and groundwater. The groundwater in the unconfined aquifer flows towards the Efteni Lake and the Biiyiik Melen River. Surface waters are divided into two main hydrochemical facies in the study area： （a） Ca2＋-HCO3-; and （b） Ca2＋, Mg2＋-HCOc-, SO4^2-. The groundwater has generally three main hydrochemical facies： （a） Ca2＋-HCO3-; （b） Ca2＋, Mg2＋-HCO3-; and （c） Ca2＋, Mg2＋-HCO3-, Cl-. The hydrochemical facies ＂a＂ and ＂b＂ dominate within shallow depths in recharge areas under rapid flow conditions, while hydrochemical facies ＂c＂ characterizes shallow and mixed groundwater, which dominate intermediate or discharge areas （near Efteni Lake and Biiyiik Melen River） during low flow conditions and agricultural contamination. Calcium and bicarbonate ions, total hardness and electrical conductivity of total dissolved solids （EC-TDS） values increase along the groundwater flow path; but these parameters remain within the limits specified by the standards set for industrial and agricultural usages.

Retrofit on Low Pressure Cylinder Flow Path Succeeded

The retrofit on flow path of low pressure cylinder of domestic made 200 MW steam turbine undertaken by Longwei Power Generation Technology Service Company Ltd by using Westinghouse technology was successful for the first time on the No. 5 unit of Zhenhai Prover Plant. Zhejiang Province. The test carried out by the Xi’an Thermal Power Research Institute showed that the thermal efficiency after the retrofit

Reservoir stress path and induced seismic anisotropy： results from linking coupled fluid-flow/geomechanical simulation with seismic modelling

We present a workflow linking coupled fluid-flow and geomechanical simulation with seismic modelling to predict seismic anisotropy induced by non-hydrostatic stress changes. We generate seismic models from coupled simulations to examine the relationship between reservoir geometry, stress path and seismic anisotropy. The results indicate that geometry influences the evolution of stress,which leads to stress-induced seismic anisotropy. Although stress anisotropy is high for the small reservoir, the effect of stress arching and the ability of the side-burden to support the excess load limit the overall change in effective stress and hence seismic anisotropy. For the extensive reservoir, stress anisotropy and induced seismic anisotropy are high. The extensive and elongate reservoirs experience significant compaction, where the inefficiency of the developed stress arching in the side-burden cannot support the excess load.The elongate reservoir displays significant stress asymmetry,with seismic anisotropy developing predominantly along the long-edge of the reservoir. We show that the link betweenstress path parameters and seismic anisotropy is complex,where the anisotropic symmetry is controlled not only by model geometry but also the nonlinear rock physics model used. Nevertheless, a workflow has been developed to model seismic anisotropy induced by non-hydrostatic stress changes, allowing field observations of anisotropy to be linked with geomechanical models.

西霞院水库流路演变及泥沙淤积分布特征

西霞院水库是小浪底水库的反调节水库,主要对小浪底水库下泄的不稳定水流进行反调节。系统梳理了2007—2022年西霞院水库调度运行方式、入库水沙、流路演变以及泥沙淤积分布特征,其成果可为西霞院水库优化减淤调度提供科技支撑。结果表明:1)西霞院水库入库年均水量为305.55亿m^(3)、年均沙量为1.34亿t,入库泥沙持续淤积造成库区流路发生显著变化,焦枝铁路老桥至坝前库段由运行初期的4条流路逐渐演变成1条流路。2)至2022年8月,西霞院水库泥沙淤积总量为7 253.6万m^(3),其中大坝—xxy07断面区间泥沙淤积量为6 964.5万m^(3);水库汛限水位131.00 m以下库容为0.184亿m^(3),淤积比为76.71%;库水位131.00~134.00 m反调节库容为0.567亿m^(3),已被侵占0.003亿m^(3)。3)西霞院水库泥沙中SiO_(2)、Al_(2)O_(3)、CaO含量占总组成的80.14%;泥沙颗粒角形因数小于等于1.30。4)西霞院水库距坝5.8 km以上现状滩面高程比淤积平衡后设计滩面高程高3 m以上,建议西霞院水库在小浪底水库排沙期水位降至132.00 m以下运行,避免上游滩面高程持续抬升侵占反调节库容。

图论在网络的可靠性分析中的应用—对基于1-critical-pathsubset网络的性能分析

本文对一种网络流模型的可靠性进行分析 .在这个模型中 ,我们考虑一对源节点和汇节点的图 ,它的弧是随机失效的 .当网络最大流大于正常工作流 ,我们就说系统是正常工作的 .考虑正常工作流的一种特殊情况 ,这里 ,所有的弧都具有相同的容量 .在这种特殊的情况中 ,潜在的系统是 1- critical的 ,也就是说 ,所有的弧的最小截大小为 2 .此时 ,问题转化为在有向图中 ,求所有的失效弧都在同一条路径上的概率 。

利用计算机视觉进行全路径人行桥振动舒适度评估

针对当前结构振动舒适度评估方法和标准只考虑结构响应而忽略结构主要使用者(人)的感受,或仅以结构的振动响应代替行人的实际感受来进行振动舒适度评估,以及传统采集方法不能同时实现结构和人的数据采集的现状,建立一种基于计算机视觉的激励‐传播‐感知全路径人行桥振动舒适度评估方法。方法采用计算机视觉技术获取行人激励下人行桥和行人的运动视频,利用分段光流法和MMTracking算法获取二者的振动响应,通过提取和转换获取相应的行人加速度,进而以加速度均方根值对人行桥振动舒适度进行评估。为验证方法的可行性和准确性,在实验室人行桥模型上进行相关试验。结果表明,基于计算机视觉的方法能够同时实现行人和人行桥响应的非接触测量,并具有较高的精度,而全路径人行桥振动舒适度评估方法比常规只将结构振动响应作为或代替行人实时响应来进行振动舒适度评估更加合理。

CFX-TASCflow在汽轮机通流设计中的应用

从应用CFX TASCflow的角度介绍了哈尔滨汽轮机厂有限责任公司 (简称哈汽 )在汽轮机通流部分全三维流场设计的应用成果 ,典型介绍了分流结构叶片、叶片汽封、多级叶片的三维流场计算和新一代亚临界6 0 0MW汽轮机高压缸通流气动设计。结果证明 ,利用CFX TASCflow能详细地分析三维粘性流场各种参数的特性及变化 ,进一步研究流场中的各种流动情况 ,控制好流场中的相关参数 ,合理地设计出高效三维叶片 。

超声波流量计的压电换能器动态性能一致性研究

超声流量计的关键组成部分是压电换能器,其性能指标决定流量计的计量准确性和稳定性。针对没有关于换能器匹配性技术指标的规范与标准这一问题,提出一种基于动态时间规整的换能器一致性评估方法,并进行快速配对研究。该方法通过回波信号时间序列的规整路径距离,进行换能器动态性能一致性评估,可以高效地实现换能器动态特性分析。水流量测量实验结果表明:通过动态时间规整算法计算得出的规整路径距离越小,配对的换能器一致性越高,零流量时的顺逆流传播时间差最大可减小到0.3 ns,零流量读数小于0.01 m/s,小流量重复性优于0.2%,满足1.5级精度标准,验证了该方法的可行性,满足了实际工程应用的需要。

Mod FLOW 在渗滤液泄漏对地下水环境影响风险分析中的应用

通过垃圾填埋场调节池渗滤液泄漏情景的设定,确定氨氮、COD为污染物的评价因子,基于Visio Mod FLOW软件中的Mod FLOW和MT3DMS模型对模拟区的地下水流场和污染物时空分布加以模拟,给出污染物的运移路径、影响范围、影响时间及污染物浓度分布情况,并布置模拟监测点,给出监测点的污染物浓度实时变化情况。

铁路空车调整的非线性规划模型研究

空车调整在技术上是一个车辆合理运用的优化问题,对其优化模型和算法的研究在理论和实际工作中都具有重要意义。该模型研究对同种铁路空车,在一个班计划时间的阶段内,以降低空车走行公里为优化目标,借鉴和参考以往研究成果,考虑避免铁路空车对流因素,以优化空车调整考虑要素为约束条件,运用运筹学思想,建立相对简洁的非线性规划模型,并通过LINGO商业软件对模型举例进行验算,能够在较短时间内求得较优方案,在验证非线性数学模型有效性的同时,可得出所建立的非线性数学模型能对空车列车开行工作起到辅助决策和对该问题可持续研究提供理论支持的结论。

Debris flow susceptibility and propagation assessment in West Koyulhisar, Turkey

Turkey is highly prone to landslides because of the geological and geographic location.The study area,which is located in a tectonically active region,has been significantly affected by mass movements.Flow type landslides are frequently observed due to this location.This study aims at determining the source area and propagation of debris flows in the study area.We used the heuristic method to extract source areas of debris flow,and then used receiver operating characteristic(ROC)curve analysis to assess the performance of the method,and finally calculated the Area under curve(AUC)values being 83.64%and 80.39%for the success rate and prediction rate,respectively.We calculated potential propagation area and runout distance with Flow-R software.In conclusion,the obtained results(susceptibility map,propagation and runout distance)are very important for decisionmakers at the region located on an active fault zone,which is highly prone to natural disasters.The outputs of this study could be used in site selection studies,designing erosion prevention systems and protecting existing human-made structures.

基于交通流分析的集装箱码头AGV拥堵消解方法

自动导引车(Automated Guided Vehicles,AGVs)的拥堵问题一直困扰着自动化集装箱码头,通常归结为无冲突路径规划问题来消解,鲜有考虑道路负载对拥堵的重要影响。以垂直布局自动化集装箱码头为背景,将负载均衡性引入了路径规划中,提出一种无拥堵的多AGVs路径规划方法。首先,建立了道路流量、道路占有率、占有率与AGV速度比之间的定量关系,据此给出了自动化集装箱码头拥堵判定方法;然后,通过引入拥堵惩罚机制,提出一种基于冲突搜索的滚动窗口无冲突路径规划方法,可以疏解AGV趋于集中带来的拥堵状况。最后,通过仿真实验验证了该方法的有效性。

Maquet Flow-i麻醉机气路结构工作原理与典型故障维修

阐述了Maquet Flow-i麻醉机稳定运行的重要性,结合麻醉机气路结构的工作原理,详细分析了该款麻醉机的4例气路部分的典型故障,并给出了具体的故障分析思路、排除方法以及检查维护与清洁消毒的操作要点,为同行分析和处理类似故障提供了参考。

Multi-decadal variations in glacier flow velocity and the influencing factors of Urumqi Glacier No.1 in Tianshan Mountains, Northwest China

Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis. Results show that the glacier flow velocity decreased from 5.5 m/a in 1980/1981 to 3.3 m/a in 2010/2011. The annual variation in the direction of glacier flow velocity in the western branch and eastern branch was less than 1°–3°, and the change of glacier flow velocity in the western branch was more dramatic than that in the eastern branch. Glacier flow velocity was influenced by glacier morphology（including glacier area, glacier length, and ice thickness）, glacier mass balance and local climate conditions（air temperature and precipitation）, the glacier morphology being the leading factor. The long-term flow velocity data set of Urumqi Glacier No. 1 contributes to a better understanding of glacier dynamics within the context of climatic warming.

MTSS: multi-path traffic scheduling mechanism based on SDN

Large-scale and diverse businesses based on the cloud computing platform bring the heavy network traffic to cloud data centers.However,the unbalanced workload of cloud data center network easily leads to the network congestion,the low resource utilization rate,the long delay,the low reliability,and the low throughput.In order to improve the utilization efficiency and the quality of services(QoS)of cloud system,especially to solve the problem of network congestion,we propose MTSS,a multi-path traffic scheduling mechanism based on software defined networking(SDN).MTSS utilizes the data flow scheduling flexibility of SDN and the multi-path feature of the fat-tree structure to improve the traffic balance of the cloud data center network.A heuristic traffic balancing algorithm is presented for MTSS,which periodically monitors the network link and dynamically adjusts the traffic on the heavy link to achieve programmable data forwarding and load balancing.The experimental results show that MTSS outperforms equal-cost multi-path protocol(ECMP),by effectively reducing the packet loss rate and delay.In addition,MTSS improves the utilization efficiency,the reliability and the throughput rate of the cloud data center network.

A modification of local path marginal cost on the dynamic traffic network

Path marginal cost （PMC） is the change in totaltravel cost for flow on the network that arises when timedependentpath flow changes by 1 unit. Because it is hardto obtain the marginal cost on all the links, the local PMC,considering marginal cost of partial links, is normallycalculated to approximate the global PMC. When analyzingthe marginal cost at a congested diverge intersection, ajump-point phenomenon may occur. It manifests as alikelihood that a vehicle may unsteadily lift up （down） inthe cumulative flow curve of the downstream links. Previously,the jump-point caused delay was ignored whencalculating the local PMC. This article proposes an analyticalmethod to solve this delay which can contribute toobtaining a more accurate local PMC. Next to that, we usea simple case to calculate the previously local PMC and themodified one. The test shows a large gap between them,which means that this delay should not be omitted in thelocal PMC calculation.

Influence of stress path change on the resistance to plastic deformation of cold rolled sheets

Flat workpieces have been tested in order to investigate the influence of stress path change （loading mode） while keeping strain path unchanged. These investigations are pertinent to the testing of cold rolled strips and to subsequent forming. The workpieces which first compressed by plane strain compression in thickness direction were then tested in perpendicular direction in order to measure the influence of strain and stress path. The tension workpieces came from flat die compression test at different deformation histories. Two different materials were investigated： 18/8 Ti stainless steel and AW-1050 aluminium. The results show that the plastic flow by tension in lengthwise direction after pre-strain by compression in thickness direction will begin at an appreciably lower stress than that of the workpieces unloaded after pre-compression. Comparing with two materials, it can be seen that both 18/8 Ti stainless steel and AW-1050 aluminium behave similarly. The drop in yield stress is lower for AW-1050 aluminium than that for 18/8 Ti stainless steel. However, reloading in different directions than in the precious step results in significantly higher strain hardening.