激光淬火硬化层的硬度分布与冷却速度

激光淬火硬化层的硬度分布,无明显的硬度梯度,这与常规淬火方法的结果不太一样。本文对激光淬火相变硬化层硬度分布状态的形成机理进行了研究,分析了无明显硬度下降梯度的硬化层对提高零件耐磨性的重要意义。     

Influence of cold-water immersion on limb blood flow after resistance exercise*

This study determined the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow following resistance exercise. Twelve males completed 4 sets of 10-repetition maximum squat exercise and were then immersed, semi-reclined, into 8°C or 22°C water for 10-min, or rested in a seated position (control) in a randomized order on different days. Rectal and thigh skin temperature, muscle temperature, thigh and calf skin blood flow and superficial femoral artery blood flow were measured before and after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure). The colder water reduced thigh skin temperature and deep muscle temperature to the greatest extent (P?<?.001). Reductions in rectal temperature were similar (0.2–0.4°C) in all three trials (P?=?.69). Femoral artery conductance was similar after immersion in both cooling conditions, with both conditions significantly lower (55%) than the control post-immersion (P?<?.01). Similarly, there was greater thigh and calf cutaneous vasoconstriction (40–50%) after immersion in both cooling conditions, relative to the control (P?<?.01), with no difference between cooling conditions. These findings suggest that cold and cool water similarly reduce femoral artery and cutaneous blood flow responses but not muscle temperature following resistance exercise.     

集中供热一次热源用于溴化锂机组的分析

通过对太原市集中供热状况的调查,提出使用集中供热一次热水作为溴化锂吸收式制冷的热源,可以提高供热管网的使用率,缓解国内用电紧张的局面。针对我国集中供热一次热源温度在120℃-150℃范围之内,提出在双效并联循环中设增压装置的办法,扩大双效循环对热源温度的适用范围。     

铝合金超常铸轧辊强化内冷实验研究

运用模拟试验方法，探讨了铸轧辊内冷水槽结构型式、冷却水流参数、在冷却水槽内设置扰流元件对铸轧辊强化内冷冷却效果的影响规律。所得结果对铝合金超常铸轧机铸轧辊的内冷结构设计具有重要参考价值。     

带冷气掺混的涡轮级三元流场分析

航空发动机向大幅度提高推重比和降低油耗的方向发展.涡轮进口温度在不断的提高.随着叶片热负荷的加大,冷却用气量也不断加大,最多已占到涡轮进口流量的20%左右.冷却气的喷射对高压涡轮级的三元流场会产生不可忽略的影响.在多叶片排三元N-S方程并行解的基础上,采用冷却气射流源项模型,研究了某带冷气掺混的高压涡轮级的流场和温度场分布特点.     

KIVA-3V程序中碰撞子程序的改进

在应用中发现KIVA-3V碰撞子程序对网格有很强的依赖性,能引起缸内喷雾场的失真。本文分析了原子程序产生失真的原因,并引入新的碰撞子程序。计算表明,新的子程序彻底根除了原子程序对网格的依赖性。     

喷雾碳化法制备超细碳酸钙

用喷雾碳化塔制备超细碳酸钙,并对超细碳酸钙的基本性能进行测定,发现其性能满足 NCC-100的要求。用XRD、SEM对得到的超细碳酸钙进行分析,得到的超细碳酸钙以球文石晶型为主。     

荷电水雾脱硫实验研究

提出塔内荷电水雾脱硫塔外固硫的新型湿法脱硫工艺,重点对荷电水雾的脱硫特性进行了研究,结果表明,增加荷电电压与液／气比均有利于增加脱硫效率,但仅采用水雾作为吸收剂,总的吸收效率相对较低;液／气比低时增加荷电电压对脱硫效率的影响并不明显,随着液／气比增加,荷电电压对脱硫效率的影响有所增强;水雾荷电后能够提高SO2溶解速率,提高SO2吸收率,有利于降低湿法脱硫初期投资及运行成本．     

Effect of controlled rolling/controlled cooling parameters on microstructure and mechanical properties of the novel pipeline steel

The study of controlled rolling/controlled cooling process parameters which affect the microstructure and mechanical properties of a novel pipeline steel has been optimized by the orthogonal experiment with four factors and three levels in this paper. However, the parameters of thermo-mechanical control process （TMCP） optimized by the Gleeble-3500 hot simulator could not satisfy performance requirements of the X100 pipeline steel. In order to improve the performance of this steel, the influence of finish cooling temperature （FCT） on the microstructure and property is studied in detail. It is found that, as this steel is thermo-mechanically treated by this set of parameters （the start heating temperature, finish rolling temperature （FRT）, FCT and cooling rate of 1,180 ℃, 810 ℃, 350 ℃ and 35 ℃/s, respectively）, the micro- structures are mainly composed of granular bainite （GB） and acicular ferrite （AF）. The effective grain sizes are below 20 μm; the steel reaches the optimal balance between the strength and the toughness; the yield strength is 695 MPa; the tensile strength is 768 MPa; the elongation is 16.6 %; the impact energy is 262 J at room temperature. All indexes could meet the requirements of X100 pipeline steel.     

机械手湿喷混凝土施工技术在高天隧道中的应用

为探索高速铁路隧道的快速湿喷技术,以混凝土喷射机械手在贵广铁路高天隧道出口的实践应用为例,从初期支护混凝土的配合比设计、原材料控制、湿喷操作技术、风压风量控制、质量控制、速凝剂掺量等方面对喷射机械手湿喷混凝土的过程进行阐述和分析,并进行了总结。结果表明,经过选择优良的湿喷机械手在高天隧道中的成功运用,以期为其他公路、铁路等隧道的初期支护施工提供一定的借鉴意义。实践证明湿喷机械手具有很好的发展前景。