时速200公里客货共线铁路接触网热滑动态数据分析及缺陷克服措施探讨

分析了既有铁路时速200公里客货共线改造工程接触网竣工后不同速度试验检测车的热滑动态数据，对接触网不同速度下缺陷存在的规律进行了研判，探讨了相应的缺陷整改措施，就如何改进工艺、减少缺陷、提高时速200公里客货共线改造工程接触网施工的一次性成功率提出了展望。

无刷直流电机混沌动态滑膜变结构算法研究

无刷直流电机(BLDCM)在运行过程中会产生非线性混沌运动,从而造成电机转矩脉动。针对BLDCM的不确定模型和存在干扰项的混沌运动系统,根据BLDCM的混沌特性、相轨迹法分析法和滑膜变结构原理,提出一种新的多模式混沌动态滑膜变结构算法。为了消除系统中存在的抖振现象,特设计一个滑模面为时变的动态PID滑模面,推导出混沌动态滑模变结构的BLDCM控制器,采用趋近律方法,对BLDCM的非线性混沌运动进行消除或抑制,最后在Matlab中建立Simulink模型。理论分析与数值仿真结果表明,混沌动态滑膜变结构算法具有可行性,能有效降低电机噪声并抑制电机的混沌运动,且控制器具有较好的动态品质。

鞋子动态止滑试验机的研制

为开发出滑倒状态更接近现实、测试结果重现性更好的高性能动态止滑试验机,采用了在电机和滑动平台之间增加一级电磁离合器和以电气比例阀控制气缸出力大小的方法,以及研制出可开合鞋楦,试验结果表明,所研制的鞋子动态止滑试验机,能够更加真实的反映出人体滑倒时的速度状态和力值大小,彻底避免了因电机的加速过程、普通调压阀控制气缸出力大小不稳定,以及鞋楦的相符性较差等对试验结果重现性的不利影响。

鞋子动态止滑试验机测试功能多样化研究

为进一步拓展鞋子动态止滑试验机的适用范围,通过对具有实用价值的木地板、冰面和雪面等测试介质的开发和鞋子与路面接触方式的研究,以及软件的合理设计,实现了测试介质和模式的多样化,以及软件中试验方法、介质和润滑剂种类等资料的自行修改及添加功能,有效促进了仪器的测试功能多样化。

关于滑模变结构控制系统中滑动状态可达性探讨

推导出了被控对象的状态方程为一般形式下的滑动状态可达性条件,并在滑模变结构控制的直流调速系统中得到了数字仿真验证。

用于沥青路面抗滑表层的石灰岩碎石筛选技术

为了探索用于沥青路面抗滑表层的石灰岩集料筛选技术,研究了不同岩性集料及其互掺集料的压碎值、磨耗值、磨光值、矿物组成及动态抗滑性能。结果表明:不同岩性互掺集料的压碎值、磨耗值、磨光值均与其互掺比例间存在较好的线性相关性,在已知单一集料的压碎值、磨耗值与磨光值的前提下,能够预测出不同比例下不同岩性互掺集料的压碎值、磨耗值与磨光值。确定了利用矿物组成筛选石灰岩的原则:首先选择白云石和石英含量较多的石灰岩,其次选择方解石含量相对较少的石灰岩,再次选择黏土矿物含量要少,甚至为0的石灰岩。基于自研仪器,提出了集料的抗滑性能控制指标Dμ集-临值。

采用不同摩擦定律动态模拟断层阶跃

众所周知,断层阶跃在某些情况下可使破裂贯通,而在另外的一些情况下则可能使破裂终止。然而,不同摩擦定律公式对跨越破裂的影响尚未得到广泛的探讨。本研究采用二维动态有限元方法探讨张性和压性两种环境下不同摩擦参数如何影响破裂跨越阶跃的能力。我们比较了线性滑动弱化摩擦和三种速率—状态依从摩擦:衰变定律、滑动定律、强速率弱化滑动定律。我们发现,对于相同有效滑动弱化距离的摩擦参数,该摩擦定律的函数形式可对最大跨越距离有显著影响。将摩擦定律调整为具有等效破裂能量时,我们发现这种摩擦定律的函数形式对跨越破裂的影响次之。最后,我们发现采用特定参数时,一旦破裂在次断层段重新起始,跨越阶跃系统的破裂延迟可导致先前未曾见到的超剪切转换模式,即使初始应力场阻碍这种转换也如此。对复杂几何形态如断层阶跃采用多种摩擦定律进行研究可有助于更好地认识和理解破裂性质对模型及统计分析中采用的摩擦定律类型的依赖性。

载人飞船返回舱外测高精度弹道计算与落点预报

针对返回舱再入返回过程中外测弹道计算精度低、稳定性差的问题,仿真分析比较了单点定位、滤波方法和动态滑窗处理等多种外弹道计算方法的精度,提出了一种弹道加权融合计算的实时自动弹道优选方法。结果表明:动态滑窗处理方法精度最高,实时自动弹道优选方法可全程获取多测元跟踪条件下的最优弹道;返回舱外测弹道计算精度和稳定性有明显提高,外测弹道落点预报精度可达到百米量级,着陆时间偏差在1 min以内。

井下高台阶柱状药包爆破技术及其应用

井下高台阶柱状药包爆破技术是利用侧向和下向两个乃至多个自由面进行爆破回采的工艺技术，是露天大孔台阶爆破技术在井下开采中的应用。通过对井下高台阶柱状药包爆破机理的初步探讨和理论分析计算，为露天台阶爆破井下化提供了依据和参考，并结合实践介绍了其在某矿的具体应用情况。

Crystal plasticity based modeling of grain boundary sliding in magnesium alloy AZ31B sheet

The aim of present work is to develop a crystal plasticity modeling approach to integrate slip,dynamic recrystallization(DRX)and grain boundary sliding(GBS)for simulating the deformation behavior and texture evolution of magnesium alloys at high temperatures.Firstly,the deformation mechanisms of an AZ31B Mg alloy sheet at 300°C were investigated by examining texture and microstructure evolution during uniaxial tension and compression tests.DRX refines microstructure at strains less than 0.2,and subsequently GBS plays a significant role during deformation process.A GBS model is developed to evaluate strain and grain rotation induced by GBS,and implemented into the polycrystal plasticity framework VPSC.The VPSC-DRX-GBS model can well reproduce the stress−strain curves,grain size,texture evolution and significant texture differences in tension and compression tests due to GBS.The calculated GBS contribution ratio in tension is obviously higher than that in compression due to easier cavity nucleation at grain boundaries under tension loading.

Trajectory tracking control for underactuated unmanned surface vehicles with dynamic uncertainties

The trajectory tracking control problem for underactuated unmanned surface vehicles(USV) was addressed, and the control system took account of the uncertain influences induced by model perturbation, external disturbance, etc. By introducing the reference, trajectory was generated by a virtual USV, and the error equation of trajectory tracking for USV was obtained, which transformed the tracking problem of underactuated USV into the stabilization problem of the trajectory tracking error equation. A backstepping adaptive sliding mode controller was proposed based on backstepping technology and method of dynamic slide model control. By means of theoretical analysis, it is proved that the proposed controller ensures that the solutions of closed loop system have the ultimate boundedness property. Simulation results are presented to illustrate the effectiveness of the proposed controller.

Dynamic assessment of rainfall-induced shallow landslide hazard

The assessment of rainfall-induced shallow landslide hazards is a significant issue in the Three Gorges Reservoir area in China due to the rapid development of land in the past two decades. In this study, a probabilistic analysis method that combines TRIGRS and the point-estimate method for evaluating the hazards of shallow landslides have been proposed under the condition of rainfall over a large area. TRIGRS provides the transient infiltration model to analyze the pore water pressure during a rainfall. The point-estimate method is used to analyze the uncertainty of the soil parameters, which is performed in the geographic information system(GIS). In this paper, we use this method to evaluate the hazards of shallow landslides in Badong County,Three Gorges Reservoir, under two different types of rainfall intensity, and the results are compared with the field investigation. The results showed that the distribution of the hazard map is consistent with the observed landslides. To some extent, the distributionof the hazard map reflects the spatial and temporal distribution of the shallow landslide caused by rainfall.

High temperature tribological behaviors of aluminum matrix composites reinforced with solid lubricant particles

The AA6061-10 wt.%B4 C mono composite, AA6061-10 wt.%B4 C-Gr(Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10 wt.%B4 C-Mo S2 hybrid composites containing 2.5, 5, and 7.5 wt.% Mo S2 particles were fabricated through stir casting. The dry sliding tribological behaviors of the mono composite and hybrid composites were studied as a function of temperature on high temperature pin-on-disc tribotester against EN 31 counterface. The wear rate and friction coefficient of the Gr-reinforced and Mo S2-reinforced hybrid composites decreased in the temperature range of 30-100 ℃ due to the combined lubrication offered by the wear protective layer and its solid lubricant phase. Scanning electron microscopy(SEM) observation of the worn pin surface revealed severe adhesion, delamination, and abrasion wear mechanisms at temperatures of 150, 200, and 250 ℃, respectively. At 150 ℃, transmission electron microscopy(TEM) observation of the hybrid composites revealed the formation of deformation bands due to severe plastic deformation and fine crystalline structure due to dynamic recrystallization.

Effective grouting area of jointed slope and stress deformation responses by numerical analysis with FLAC^(3D)

To study the grouting reinforcement mechanism in jointed rock slope, first, the theoretical deduction was done to calculate the critical length of slipping if the slope angle is larger than that of joint inclination; Second, the numerical calculation model was founded by FLAG^3D, so as to find the stress and deformation responses of rock mass in the state before and after grouting, the analysis results show that the range between the boundary of critical slipping block and the joint plane that passes the slope toe is the effective grouting area （EGA）. After excavation, large deformation occurs along the joint plane. After grouting, the displacements of rock particles become uniform and continuous, and large deformations along the joint plane are controlled; the dynamic displacement can re- flect the deformation response of slope during excavation in the state before and after grouting, as well as the shear location of potential slip plane. After grouting, the dynamic displacement of each monitoring point reaches the peak value with very few time steps, which indicate that the parameters of the joint plane, such as strength and stiffness, are improved; the stress field becomes uniform. Tensile area reduces gradually; whole stability of the slope and its ability to resist tensile and shear stress are improved greatly.

Dynamic wetting of rolling oil on aluminum surfaces

Static and dynamic contact angles of stock oil and its solutions with additives（fatty acid, fatty alcohol, fatty methyl ester usually used in rolling aluminum） were measured on aluminum surface （Alloy 1145） by sessile drop technique on an OCA35 dynamic contact angle tester. The effect of additive on the drop spreading was investigated as well. It is shown that the drop spreads very quickly in the first 500 ms after the lubricant contacts with the aluminum surface, and then does slowly later. The dynamic contact angle decreases exponentially with time. In contrast to the stock oil, although addition of polarity additive of long chain alkyl into stock oil is able to decrease the surface tension of solutions, it weakens the wetting dynamic, which results fi＇om the adsorption at the expanding solid/liquid interface. Among the same long chain polarity organic compounds used, dynamic wetting decreases in the order of fatty acid, fatty alcohol and fatty ester. The blend of fatty alcohol and fatty methyl ester can improve the oil wetting dynamics and promote the lubricant spreading.

Flow field simulation and establishment for mathematical models of flow area of spool valve with sloping U-shape notch machined by different methods

Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape notch on the spool, such as mass flow rates, flow coefficients, effiux angles and steady state flow forces under different operating conditions. At last, the reliability of the mathematical model of the flow area for the sloping U-shape notch orifice on the spool was demonstrated by the comparison between the orifice area curve derived and the corresponding experimental data provided by the test. It is presented that the bottom arc of sloping U-shape notch （ABU） should not be omitted when it is required to accurately calculate the orifice area of ABU. Although the theoretical flow area of plain bottom sloping U-shape notch （PBU） is larger than that of ABU at the same opening, the simulated mass flow and experimental flow area of ABU are both larger than these of PBU at the same opening, while the simulated flow force of PBU is larger than that of ABU at the same opening. Therefore, it should be prior to adapt the ABU when designing the spool with proportional character.

Nonlinear dynamic fractional sliding mode control to the motor of mining locomotive

The harsh operating environment and complex operating conditions of the mine electric locomotive affect the control performance of the locomotive traction motor.In order to improve the speed control performance of electric locomotive traction motors,a dynamic fractional-order sliding mode control(DFOSMC)algorithm considering uncertain factors was proposed.A load torque sliding mode observer was designed for the complex load disturbance of the traction motor,and its observations were integrated into the DFOSMC controller to overcome the influence of load disturbance.Finally,the stability of the designed controller was proved by Lyapunov's theorem.Besides,the control performance of DFOSMC controller was compared with integer-order sliding mode controller and fractional-order sliding mode controller through simulation experiments.Compared with integer-order sliding mode and fractional-order sliding mode controllers,the dynamic and static performance of the DFOSMC controller with load observation is better,and it has stronger anti-interference ability.The DFOSMC controller effectively improves the control performance of the traction motor of the mining locomotive.

Dynamic analysis, simulation, and control of a 6-DOF IRB-120 robot manipulator using sliding mode control and boundary layer method

Because of its ease of implementation,a linear PID controller is generally used to control robotic manipulators.Linear controllers cannot effectively cope with uncertainties and variations in the parameters;therefore,nonlinear controllers with robust performance which can cope with these are recommended.The sliding mode control(SMC)is a robust state feedback control method for nonlinear systems that,in addition having a simple design,efficiently overcomes uncertainties and disturbances in the system.It also has a very fast transient response that is desirable when controlling robotic manipulators.The most critical drawback to SMC is chattering in the control input signal.To solve this problem,in this study,SMC is used with a boundary layer(SMCBL)to eliminate the chattering and improve the performance of the system.The proposed SMCBL was compared with inverse dynamic control(IDC),a conventional nonlinear control method.The kinematic and dynamic equations of the IRB-120 robot manipulator were initially extracted completely and accurately,and then the control of the robot manipulator using SMC was evaluated.For validation,the proposed control method was implemented on a 6-DOF IRB-120 robot manipulator in the presence of uncertainties.The results were simulated,tested,and compared in the MATLAB/Simulink environment.To further validate our work,the results were tested and confirmed experimentally on an actual IRB-120 robot manipulator.

Directly searching method for slip plane and its influential factors based on critical state of slope

In order to determine the slip plane of slope directly by the calculation results of strength reduction method, and analyze the influential factors of slope stability, a numerical model was established in plane strain mode by FLAC3D for homogeneous soil slope, whose parameters were reduced until the slope reached the critical state. Then FISH program was used to get the location data of slip plane from displacement contour lines. Furthermore, the method to determine multiple slip planes was also proposed by setting different heights of elastic areas. The influential factors for the stability were analyzed, including cohesion, internal friction angle, and tensile strength. The calculation results show that with the increase of cohesion, failure mode of slope changes from shallow slipping to the deep slipping, while inclination of slip plane becomes slower and slipping volume becomes larger; with the increase of friction angle, failure mode of slope changes from deep slipping to shallow slipping, while slip plane becomes steeper and upper border of slip plane comes closer to the vertex of slope; the safety factor increases little and slip plane goes far away from vertex of slope with the increase of tensile strength.

Plan IQ和Monaco优化乳腺癌改良根治术后放射治疗计划的剂量学研究

目的研究分析Monaco计划系统设计乳腺癌改良根治术放射治疗动态滑窗调强(DMLC)计划和容积弧形调强(VMAT)计划的剂量学特点,并与乳腺癌的三维适形放射治疗(3D-CRT)计划进行比较,归纳DMLC、VMAT、3D-CRT 3种放射治疗技术的剂量学优缺点,并利用Plan IQ软件技术预测和评估乳腺癌改良根治术放射治疗计划质量水平和难易程度,从而为物理师和临床医师优化放射治疗计划提供指导。方法选取2017年6月至2018年6月医院收治的10例乳腺癌改良根治术后患者(左乳5例、右乳5例),先应用Plan IQ预测各乳腺癌计划靶区和危及器官所能达到的剂量学范围,然后根据Plan IQ的预测值和Monaco计划系统优化乳腺癌DMLC、VMAT计划,最后将优化的计划导入Plan IQ进行评估,从而比较DMLC、VMAT、3D-CRT 3种放射治疗技术的剂量学差异。结果与3D-CRT计划相比,7野DMLC和VMAT计划在很大程度上提高了靶区剂量均匀性和适形性,且对危及器官的保护较好;7野DMLC计划可以获得更加良好的靶区剂量分布,均匀性指数(HI)值较低,尤其是对肺、心脏等危及器官的保护较好;而VMAT计划适形性指数(CI)值较高,具有更好的适形性,且计划执行时间较少。DMLC和VMAT计划结果可以很好地符合Plan IQ的预测结果。结论在使用Monaco计划系统设计乳腺癌改良根治术放射治疗计划时,7野DMLC和VMAT两种调强计划均能满足临床要求,推荐使用7野DMLC技术,以获得更好的靶区剂量分布和较低的危及器官受量,而Plan IQ在计划预测和优化评估方面具有很好的临床指导作用。