Simulation of the effect of a magnetically insulated anode on a low-power cylindrical Hall thruster

The intersection point of the characteristic magnetic field line (CMFL) crossing the anode boundary with the discharge channel wall,and its influence on thruster performance and the energy and flux of ions bombarding the channel wall,have been studied numerically.The simulation results demonstrate that with the increase in distance from the crossover point of the CMFL with the channel wall to the bottom of the thruster channel,the ionization rate in the discharge channel gradually increases;meanwhile,the ion energy and ion current density bombarding the channel wall decreases.When the point of the CMFL with the channel wall is at the channel outlet,the thrust,specific impulse,and efficiency are at a maximum,while the ion energy and ion current density bombarding the channel wall are at a minimum.Therefore,to improve the performance and lifetime of the thruster,it is important to control the point of intersection of the CMFL with the channel wall.     

南水北调中线总干渠豫北"96·8"洪水调查分析

根据南水北调中线总干渠初步设计工程水文计算要求，进行了南水北调中线总干渠交叉河流的洪水调查、分析研究工人和。“９６．８”洪水调查主要是针对豫北地区与总干渠交叉的２５条河流进行的，外业调查范围一般选在总干渠与河流交叉断面上下游１～２ｋｍ的河段上，主要摸清“９６．８”洪水发生日期、洪痕位置、洪水地流情况以胩下游水利工程及卡口工程情况、洪水淹没范围等。重点对洪痕高程进行测量。着重介绍调查洪水洪峰流量计算     

应用型人才培养背景下的参与式教学在分析化学课程教学中的应用

将参与式教学模式应用到分析化学课程的教学中,根据应用型人才培养目标及课程特点提出了六种可行的参与方式,有效地激发学生的学习兴趣,教学效果明显提升。     

采煤机割煤过程中粉尘沿程分布运移的仿真与监测

研究采煤机在割煤落煤过程中,粉尘在综采工作面的沿程分布情况。利用计算流体力学(CFD)软件,结合某煤矿1207工作面的具体特点和实测数据,分别模拟了采煤机在顺风割煤和逆风割煤2种不同工作条件下,工作面的全尘粉尘和呼吸性粉尘在巷道的可视化分布规律。     

1-(2-吡啶基)-3-甲基-4-三氟甲酰基-5-吡唑酮的合成及其与Fe~(3+)显色反应研究

合成了新型的酰基吡唑啉酮标题化合物,通过红外、核磁、质谱和元素分析对其进行表征,并研究了其与Fe~(3+)的显色反应。实验结果表明,该化合物对Fe~(3+)具有高选择的显色反应特性,Fe~(3+)质量浓度为0.18~1.8μg/mL,与相对吸光度呈良好的线性关系A=0.423ρ-0.020(μg/mL),相关性系数r=0.999 3,最低检出限为0.064μg/mL(n=11)。     

综采放顶煤工作面相似模拟研究

综采放顶煤工作面上覆岩层的破坏和冒落是一个复杂的力学过程。用相似材料模拟试验法,对放顶煤开采上覆岩层运动和矿压显现规律进行研究,得出了上覆岩层运动特点和工作支承压力分布规律,并对顶煤破碎与支承压力的关系进行了分析,为工作面矿压控制参数选择提供了依据。     

鹤壁六矿煤与瓦斯突出特点及其控制因素分析

论文以鹤壁六矿34次突出为例,统计分析了该矿的煤与瓦斯突出特点,并总结了控制该矿瓦斯突出的各种因素,即:埋藏深度、地质构造、构造软煤、高压瓦斯、作业工艺,这对有效地防治煤与瓦斯突出,消除或降低煤与瓦斯突出事故造成的危害,具有重要的现实意义。     

浅谈综采放顶煤工作面防灭火措施

潘津煤矿煤层较厚且易自然发火,设计采用综采放顶煤采煤法。为了有效防止采煤工作面自然发火,通过对综放工作面煤层自燃特点的分析,提出了预防性灌浆、注氮、喷洒阻化剂、均压防灭火、地面填埋堵漏和监测监控等防灭火综合措施,为矿井生产中防灭火措施的选用提供了借鉴。     

Investigation of short-channel design on performance optimization effect of Hall thruster with large height–radius ratio

In this study, the neutral gas distribution and steady-state discharge under different discharge channel lengths were studied via numerical simulations. The results show that the channel with a length of 22 mm has the advantage of comprehensive discharge performance. At this time, the magnetic field intensity at the anode surface is 10% of the peak magnetic field intensity. Further analysis shows that the high-gas-density zone moves outward due to the shortening of the channel length, which optimizes the matching between the gas flow field and the magnetic field, and thus increases the ionization rate. The outward movement of the main ionization zone also reduces the ion loss on the wall surface. Thus, the propellant utilization efficiency can reach a maximum of 96.8%. Moreover, the plasma potential in the main ionization zone will decrease with the shortening of the channel. The excessively short-channel will greatly reduce the voltage utilization efficiency. The thrust is reduced to a minimum of 46.1 mN. Meanwhile, because the anode surface is excessively close to the main ionization zone, the discharge reliability is also difficult to guarantee. It was proved that the performance of Hall thrusters can be optimized by shortening the discharge channel appropriately, and the specific design scheme of short-channel of HEP-1350PM was defined, which serves as a reference for the optimization design of Hall thruster with large height–radius ratio. The short-channel design also helps to reduce the thruster axial dimension, further consolidating the advantages of lightweight and large thrust-to-weight ratio of the Hall thruster with large height–radius ratio.