A comparative study on kinetics and dynamics of two dump truck lifting mechanisms using MATLAB simscape

In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.

Rainfall-triggered waste dump instability analysis based on surface 3D deformation in physical model test

Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.

Shear resistance characteristics and influencing factors of root-soil composite on an alpine metal mine dump slope with different recovery periods

Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic changes and the influencing factors of the soil reinforcement effect of plant species after artificial vegetation restoration under different recovery periods.We selected dump areas of the Delni Copper Mine in Qinghai Province,China to study the relationship between the shear strength and the peak displacement of the root-soil composite on the slope during the recovery period,and the influence of the root traits and soil physical properties on the shear resistance characteristics of the root-soil composite via in situ direct shear tests.The results indicate that the shear strength and peak displacement of the rooted soil initially decreased and then increased with the increase of the recovery period.The shear strength of the rooted soil and the recovery period exhibited a quadratic function relationship.There is no significant function relationship between the peak displacement and the recovery period.Significant positive correlations(P<0.05)exists between the shear strength of the root-soil composite and the root biomass density,root volume density,and root area ratio,and they show significant linear correlations(P<0.05).There are no significant correlations(P>0.05)between the shear strength of the root-soil composite and the root length density,and the root volume ratio of the coarse roots to the fine roots.A significant negative linear correlation(P<0.05)exists between the peak displacement of the rooted soil and the coarse-grain content,but no significant correlations(P>0.05)with the root traits,other soil physical property indices(the moisture content and dry density of the soil),and slope gradient.The coarse-grain content is the main factor controlling the peak displacement of the rooted soil.

A Predictive Energy Management Strategies for Mining Dump Trucks

The plug-in hybrid vehicles(PHEV)technology can effectively address the issues of poor dynamics and higher energy consumption commonly found in traditional mining dump trucks.Meanwhile,plug-in hybrid electric trucks can achieve excellent fuel economy through efficient energy management strategies(EMS).Therefore,a series hybrid system is constructed based on a 100-ton mining dump truck in this paper.And inspired by the dynamic programming(DP)algorithm,a predictive equivalent consumption minimization strategy(P-ECMS)based on the DP optimization result is proposed.Based on the optimal control manifold and the SOC reference trajectory obtained by the DP algorithm,the P-ECMS strategy performs real-time stage parameter optimization to obtain the optimal equivalent factor(EF).Finally,applying the equivalent consumption minimization strategy(ECMS)realizes real-time control.The simulation results show that the equivalent fuel consumption of the P-ECMS strategy under the experimentally collected mining cycle conditions is 150.8 L/100 km,which is 10.9%less than that of the common CDCS strategy(169.3 L/100 km),and achieves 99.47%of the fuel saving effect of the DP strategy(150 L/100 km).

Multi-objective Stability Control Algorithm of Heavy Tractor Semi-trailer Based on Differential Braking

Rollover and jack-knifing of tractor semi-trailer are serious threats for vehicle safety, and accordingly active safety technologies have been widely used to reduce or prevent the occurrence of such accidents. However, currently tractor semi-trailer stability control is generally only a single hazardous condition (rollover or jack-knifing) control, it is difficult to ensure the vehicle comprehensive stability of various dangerous conditions. The main objective of this study is to introduce a multi-objective stability control algorithm which can improve the vehicle stability of a tractor semi-trailer by using differential braking. A vehicle controller is designed to minimize the likelihood of rollover and jack-knifing. First a linear vehicle model of tractor semi-trailer is constructed. Then an optimal yaw control for tractor using differential braking is applied to minimize the yaw rate and lateral acceleration deviation of tractor, as well as the hitch articulation angle of tractor semi-trailer, so as to improve the vehicle stability. Second a braking scheme and variable structure control with sliding mode control are introduced in order to achieve the best braking effect. Last Fishhook maneuver is introduced to the active safety simulation and the active control system effect verification. The simulation results show that multi-objective stability control algorithm of semi-trailer could improve the vehicle stability significantly during the transient maneuvers. The proposed multi-objective stability control algorithm is effective to prevent the vehicle rollover and jackknifing.

Optimization for vehicle scheduling in iron and steel works based on semi-trailer swap transport

In order to solve internal logistics problems of iron and steel works,such as low transportation efficiency of vehicles and high transportation cost,the production process and traditional transportation style of iron and steel works were introduced.The internal transport tasks of iron and steel works were grouped based on cluster analysis according to demand time of the transportation.An improved vehicle scheduling model of semi-trailer swap transport among loading nodes and unloading nodes in one task group was set up.The algorithm was designed to solve the vehicle routing problem with simultaneous pick-up and delivery(VRPSPD) problem based on semi-trailer swap transport.A solving program was written by MATLAB software and the method to figure out the optimal path of each grouping was obtained.The dropping and pulling transportation plan of the tractor was designed.And an example of semi-trailer swap transport in iron and steel works was given.The results indicate that semi-trailer swap transport can decrease the numbers of vehicles and drivers by 54.5% and 88.6% respectively compared with decentralized scheduling in iron and steel works,and the total distance traveled reduces by 43.5%.The semi-trailer swap transport can help the iron and steel works develop the production in intension.

Modal Correlation Based Analysis on Dynamic Characters of a Commercial Semi-Trailer's Chassis Frames

In order to evaluate two different schemes＇ structural dynamic characters, dynamic response analysis of a commercial truck＇s main chassis frames is carried out. On the basis of correlation study between the tested and calculated modal results, the assembled frames＇ finite element analysis （FEA） models with sufficient precision are built up. Random response analysis in frequency domain is carried out with these FEA models, RMS values of yon Mises and main principle stresses of these two frames are obtained. It shows that the analysis resuits of the distributing tendency and concrete value ranges are coincident very well with test results. And from the results, it could be concluded that frames of scheme A endures relative better loading conditions and should be adopted as the final scheme.

600WM汽轮机高压主汽门及高压调门DUMP阀故障分析与处理

介绍了DUMP阀的作用、结构原理,结合某电厂高压主汽门、高压调门几次故障案例,分析研究DUMP阀发生故障的原因,并提出相应的处理措施,为类似问题的解决提供了参考和借鉴。

The Roll Stability Analysis of Semi-Trailer Based on the Wheel Force

It is different for the liquid tank semi-trailer to keep roll stability during turning or emergency voidance,and that may cause serious accidents.Although the scholars did lots of research about the roll stability of liquid tank semi-trailer in theory by calculating and simulation,how to make an effective early warning of rollover is still unsolved in practice.The reasons include the complex driving condition and the difficulty of the vehicle parameter obtaining.The feasible method used currently is evaluating the roll stability of a liquid tank semi-trailer by the lateral acceleration or the attitude of the vehicle.Unfortunately,the lateral acceleration is more useful for sideslip rather than rollover,and the attitude is a kind of posterior way,which means it is hard to take measures to cope with the rollover accident when the attitude exceeds the safety threshold.Considering the movement of the vehicle is totally caused by the wheel force,the rollover could also be predicted by the changing of the wheel force.Therefore,in this paper,we developed a method to analyze the roll stability by the vertical wheel force.A thorough experiment environment is established,and the effectiveness of the proposed method is verified in real driving conditions.

Legacy Gold Mine Sites & Dumps in the Witwatersrand: Challenges and Required Action

Legacy mine shafts and waste dumps in the Witwatersrand continue to create social and environmental challenges for communities, even in areas where gold mining ceased over 100 years ago. The slow pace of eradication of these gold mine shafts and waste dumps (or lack thereof) results in conflict between the communities and authorities, particularly the Department of Mineral Resources and Energy (DMRE) as the relevant authority in the field of environmental management in mining. This paper examines, through a literature review, the past and present legislative framework that resulted in legacy mine shafts and dumps and how communities find themselves living next to these mine sites, which results in social and environmental problems. The paper further explores the governments, particularly the DMRE, proposed initiatives to empower those who intend to extract value from the abandoned mines while curbing the scourge of crime in affected communities.

Cycle Time Analysis of Open Pit Mining Dump Trucks

This study demonstrates a practical cycle time analysis of dump truck haulage system of “Ukhaa Khudag” open-pit coal mine located in Umnugobi Province, Mongolia. It examines the possibility of minimizing the cycle time of the haulage system as well as factors impacting the speed of the dump truck. The current study divides the open pit mine road for the dump trucks into five sections which are bench road, ramp, surface road, dump road uphill, and dump road. Meanwhile, it investigates the influence of the length, the grade, and the rolling resistance of the road section on the cycle time. The data is analyzed using mathematical regression methods via Microsoft Excel program. For each of the five road sections, we compare the statistical calculations of three regression models: linear, quadratic and exponential;thus, a total of thirty regression models are obtained in this research. Accordingly, the cycle time for each road section is predicted by the most accountable model. The loaded and empty direction of the movement is measured and calculated for each road section, and it appears that the difference between the calculated mean value and the actual cycle time of the models is 0.82 seconds with a relative error of 2.51 percent.

露天煤矿排土场边坡植被恢复群落稳定性研究

为了揭示露天煤矿排土场边坡植被恢复群落稳定性的动态特征和变化模式,以内蒙古北电胜利露天煤矿4个排土场为研究对象,选取Shannon-Wiener多样性指数、Margalef丰富度指数、Pielou均匀度指数和Simpson优势度指数、植被盖度、植被高度、地上和地下生物量8个指标,构建了基于群落结构稳定性与群落功能稳定性的排土场边坡植被恢复群落稳定性评价体系,采用综合评价法对处于人工植被恢复中的内排土场和恢复年限分别为4 a、5 a、8 a的沿帮排土场、南排土场和北排土场的南、北方向边坡植被恢复群落稳定性进行综合评估,并对群落稳定性因子与土壤含水量、有机质、全氮、全磷、全钾等环境因子间关系进行分析,探究影响排土场边坡群落稳定性的影响因素。结果表明:(1)随着恢复年限的增加,边坡植被群落稳定性整体呈稳步上升趋势,但与草原站背景值相比,其综合评价指数处于较不稳定或不稳定状态。(2)随着恢复年限的增加,排土场边坡群落稳定性由结构稳定性主导转向功能稳定性主导。恢复初期受人工影响,物种多样性提高,结构稳定性较高,随着时间的推移,结构稳定性波动下降,功能稳定性上升,其中地下生物量增长迅速,生物量向地下转移,进而形成矿区特有的植物群落结构稳定与功能稳定转变特征。(3)从坡向来看,随着恢复年限的增加,边坡群落稳定性逐渐由南坡优于北坡转变为北坡优于南坡。(4)南坡的结构稳定性与环境因子的相关性较高,而北坡的功能稳定性与环境因子相关性较高,表明不同坡向的群落采用了不同的响应策略以适应环境的变化,丰富的有机质和全氮含量对排土场边坡群落功能性稳定性会产生积极影响。

基于土壤肥力恢复力模型的河曲露天煤矿复垦治理效果评价

以河曲旧县露天煤矿排土场为研究对象,采用模糊层次分析法(FAHP)和专家评分理论法建立了露天煤矿排土场土壤肥力综合评价模型,获得土壤结构稳定性、土壤保水能力、土壤保肥能力及土壤生物活性4项准则和25个因素,利用YAAHP计算软件确定了排土场土壤肥力恢复力各影响因素的权重。结果表明,评价体系准则层中土壤保肥能力权重最大(0.5477),其次分别是土壤保水能力(0.1980)、土壤生物活性(0.1408)和土壤结构稳定性(0.1135),因素层有机质F1权重最高(0.1162);根据现场抽样,已复垦区的土壤质量水平要高于未复垦区的土壤质量水平,整体来看土壤质量水平均处于中等偏下和较差水平,土壤恢复力的主要因素是土壤保肥能力,特别是土壤有机质含量。土壤肥力恢复力模型为提高排土场土壤质量、加快土壤重构、促进土壤生态系统恢复提供治理思路。

软弱基底排土场边坡逆排堆高速率及稳定性控制方法研究

针对软弱基底排土场逆排堆高过程的稳定性控制需求,构建了堆高速率与软弱土层强度参数对应关系,提出了一种不同堆高速率条件下排土场边坡稳定性分析方法。针对某排土场案例,开展了软弱基底土样不同固结度快剪试验,结果显示,随着固结度增大,内摩擦角以双曲线型函数逐渐增大,黏聚力基本保持不变。结合硬化土模型,利用有限元法分析了预压堆载下软弱土层平均固结度演化规律,联合直剪试验结果构建了强度参数与堆载厚度、固结时长的定量关系。结果表明,较厚软弱层在堆载和固结时长均相同时具有更低的内摩擦角;当堆载较小、固结时长相同时,软弱层具有更高的内摩擦角;当预压固结时长由50 d提高到100 d时,排土场边坡破坏模式从沿基底滑动变成堆排土体内部滑动,继续延长预压时长不再提升整体稳定性。

大型矿用自卸车厢斗装载程序分析及力学特性研究

自主装卸是智能矿山建设中亟待突破的关键技术,电铲-矿用自卸车合理的装载程序能够显著降低电铲装卸作业难度,降低复杂动态载荷对厢斗力学性能的影响。以某型号矿用自卸车厢斗为研究对象,依据厢斗容量标定方法建立了厢斗的堆装模型,确定厢斗堆装容积;分析了厢斗安装特点及结构特征,结合现场实际装载经验,提出了三种不同的装载程序,并利用离散元方法对三种装载程序进行仿真分析,研究不同装载程序下厢斗装载量、物料均匀性及底板承受的压力等;在此基础上,通过仿真分析研究厢斗满载工况下的力学特性。结果表明,在厢斗装载过程中将装载位置放在厢斗满载重心及前侧位置可提升装载量,各铲装载位置尽量靠近厢斗横向方向的中轴线,本文提出的装载程序二的装载量最大,物料可通过自身堆积特性装满厢斗,并在厢斗内部的均匀性更好,且物料装满后厢斗底板的总压力最小,当满载后厢斗的最大变形量为7.50 mm,最大应力为326.85 MPa,满足刚度、强度设计要求。

规制日本向海洋处置核污染水的相关国际法理剖析

日本向海洋处置核污染水问题,违反了《伦敦倾废公约》及其《1996年议定书》有关风险预防、防止与减少及控制海洋环境污染、加强国际合作、开展海洋环评、可持续发展等规定,也暴露出国际法中相关规定在应对此类问题上存在规则不严密、适用局限性以及约束力度不足等缺陷。为了全面、有效规制日本向海洋处置核污染水,《伦敦倾废公约》及其《1996年议定书》需要进一步做出有针对性的修订与完善,切实加强履约工作,充分发挥国际法作用,以维护海洋生态环境安全。

欧盟对中国反倾销的贸易限制效应研究——基于2010—2022年月度贸易数据

本文将欧洲联盟2010—2022年间对我国发起的反倾销案件进行完整梳理,首先选取我国遭受欧盟反倾销的典型涉案产品,详细阐述欧洲联盟进口量和进口额在反倾销前后的变动趋势。其次,使用2010—2022年间欧洲联盟与我国的HS6位码月度贸易数据构建动态面板模型,采用差分广义矩估计,确定以季度为研究周期,更为合理地动态考察欧洲联盟对我国反倾销的贸易限制效应,并区分反倾销节点异质性和产品异质性。最后,采用反事实估计法量化欧洲联盟对我国反倾销典型涉案产品的贸易限制比例。研究结果表明,欧洲联盟对我国反倾销典型涉案产品存在贸易限制效应,立案调查的贸易限制效应通常不存在滞后,而肯定性终裁的贸易限制效应往往存在滞后。本文对我国出口企业如何预警欧洲联盟发起的反倾销具有实际意义,也有助于重点出口行业合理调整生产,避免欧洲联盟对我国反倾销带来的损失。若贸易数据可以细分反倾销涉案产品的HS8位码,则能进一步将产品创新可能带来的影响纳入考察。

海洋倾废行为的立法规制研究

近十几年来,随着中国工业、农业的蓬勃发展,人口数量的增加,海洋运输和海洋开发技术的进步,大批港口和城市的兴起和扩建,出现了未取得许可证或者不按照许可证的规定向海洋倾倒废弃物的现象。大规模地向海洋排放有毒、有害废弃物,会严重污染海洋资源,其中的关键因素之一是对海洋环境污染责任人违法行为的低成本惩罚。海洋倾废行为给海洋生态环境带来极大的隐患,使人类的生活面临严峻的挑战。面对日趋加重的污染情况,整个国际社会认识到通过立法保护海洋环境的关键性和紧迫性。

充水作用下露天煤矿内排土场边坡稳定性分析

为分析废弃矿坑改造成蓄水湖时充水高度对内排土场边坡稳定性的影响,采用室内相似试验、数值模拟和理论分析的方法对不同水位高度下内排土场边坡稳定性进行研究。研究结果表明:随着充水高度的增加,浸润线运移速度、边坡最大位移、孔隙水压力和边坡土体受到的压力整体呈增长趋势。充水高度越大,边坡倾角越大,边坡稳定系数越低。研究结论为露天煤矿改造成蓄水湖或蓄能水电站项目工程提供参考。

反倾销嵌入全球生产网络的级联效应仿真研究

本研究将复杂网络理论应用于投入产出模型并将其引入宏观经济学生产函数理论模型,对反倾销嵌入全球生产网络的内在机理与其产生的级联效应展开探讨与仿真模拟分析.研究发现:基于网络视角与投入产出关系,反倾销冲击对中间产品的贸易抑制作用要明显大于最终产品,多次跨境的中间品将会累积增加反倾销带来的贸易成本;反倾销带来的行业引致需求量降低与出口贸易受到抑制以及行业与国家总产出水平的波动等影响,会沿着以中间品贸易为基础的全球生产网络中的投入产出关系进行传播,从而产生显著的级联效应,并且该效应会随着不同国家-部门节点之间的联系紧密程度(贸易量)的降低而衰减;反倾销产生的级联效应不仅涉及全球生产网络中直接关联节点即涉案国(调查国与被调查国)的国内上下游行业,而且波及间接关联节点即非涉案国的第三方国家和地区,进而影响全球多边贸易发展,同时,级联效应也阻碍了网络节点参与全球价值链生产分工,导致了节点隶属国(地区)的国内价值链被拉长;反倾销嵌入全球生产网络后,会通过整个生产网络产生总量波动效应,从而改变全球生产网络的拓扑结构,即全球生产网络变的相对稀疏、节点间网络距离拉长等.