切削中防止积屑瘤产生的几种措施

在机械切削过程中,积屑瘤的产生,将直接影响工件表面质量和尺寸精度。针对这一情况,所采用的几种措施防止积屑瘤的产生。     

大侧倾角下轮胎稳态侧倾刷子模型

针对国内外关于轮胎侧倾力学特性模型的研究现状,在小侧倾角下轮胎稳态侧倾理论模型基础上,通过引入“临界侧倾角”和“饱和侧倾角”的概念,建立了大侧倾角下的轮胎稳态侧倾理论模型．     

高等学校学生助学金量化评定方法研究与实践

本研究对高等学校助学金量化评定方法进行了一番探索,确定了班级综合测评名次值、班级贫困状况名次值、贫困名次值调整系数三个量化指标参数,并在此基础上归纳总结出了助学金评定的量化公式,给出了评定过程流程图,对高校助学金评定工作有一定的参考价值。     

Adsorption characteristics of activated carbon derived from scrap tires for malachite green: Influence of small organics

The influence of small organics on the adsorption characteristics of activated carbon produced from industrial pyrolytic tire char（APTC）for malachite green（MG） was investigated by a batch method. Phenol was chosen as the representative of small organics. The effects of phenol on adsorption equilibrium, kinetics and thermodynamics were studied systematically. The results indicate that APTC is a potential adsorbent for MG. The presence of phenol decreases the adsorption capacity of APTC for MG, but improves the rate of adsorption, while the adsorption characteristics, such as equilibrium, kinetics and thermodynamics are not affected by phenol. The adsorption equilibrium data follow Langmuir isotherm and the kinetic data are well described by the pseudo-second-order kinetic model. The adsorption process follows intra-particle diffusion model and the adsorption rate is determined by more than one process. Thermodynamic study shows that the adsorption is an endothermic and spontaneous physisorption process.     

Fe基激光熔覆工艺参数对涂层成形的影响

在离焦量、送粉量、送粉气流量一定的情况下,研究了激光功率、扫描速度、激光束与送粉束相对位置等对激光熔覆成形的影响。结果表明:送粉束在前,激光束在后,激光功率为6 kW时,扫描速度为1.5 m/min时的熔覆层成形较好;激光功率为7 kW,扫描速度为1.2～1.4 m/min时的激光熔覆层成形较好。送粉束在后,激光束在前,激光功率为7 kW,扫描速度为0.5～0.6m/min时的激光熔覆成形较好。熔覆层的组织形态主要有平面层、胞状晶和树枝晶。     

“后方法”教学理论及其对高校英语课堂教学的启示

中国高校英语课堂存在诸多亟待解决的问题.研究依据“后方法”教学理论的教学参量与宏观策略,通过调查问卷方式调查高校英语课堂教学现状并诊断其存在的问题,在此基础上总结出如下四方面的启示：转换教师角色;从实践循环到理论创造;注重课堂活动,打造和谐氛围：将语言与文化有机结合.这些启示对于提高课堂教学质量将起到一定的促进作用.     

汽车轮胎的科学使用与养护

主要介绍了汽车轮胎的功用、类型和规格型号,探究了轮胎的选用及轮胎的使用与养护等方面的问题。     

推理公式中汇流参数对洪水计算的影响分析

在我国小型水利水电工程设计的洪水计算中,水科院推理公式法使用最广,其汇流参数m值是推理公式计算洪峰流量的重要参数,本文用具体计算实例,通过对m取值对洪水计算结果影响的定量分析,说明该值在洪水计算中的重要性,并推荐一种检验m取值合理性的简单方法。     

The effects of eccentric exercise-induced muscle damage on running kinematics at different speeds

Abstract

This study investigated the effects of knee localised muscle damage on running kinematics at varying speeds. Nineteen young women (23.2 ± 2.8 years; 164 ± 8 cm; 53.6 ± 5.4 kg), performed a maximal eccentric muscle damage protocol (5 × 15) of the knee extensors and flexors of both legs at 60 rad · s^-1. Lower body kinematics was assessed during level running on a treadmill at three speeds pre- and 48 h after. Evaluated muscle damage indices included isometric torque, muscle soreness and serum creatine kinase activity. The results revealed that all indices changed significantly after exercise, indicating muscle injury. Step length decreased and stride frequency significantly increased 48 h post-exercise only at the fastest running speed (3 m · s^-1). Support time and knee flexion at toe-off increased only at the preferred transition speed and 2.5 m · s^-1. Knee flexion at foot contact, pelvic tilt and obliquity significantly increased, whereas hip extension during stance-phase, knee flexion during swing-phase, as well as knee and ankle joints range of motion significantly decreased 48 h post-exercise at all speeds. In conclusion, the effects of eccentric exercise of both knee extensors and flexors on particular tempo-spatial parameters and knee kinematics of running are speed-dependent. However, several pelvic and lower joint kinematics present similar behaviour at the three running speeds examined. These findings provide new insights into how running kinematics at different speeds are adapted to compensate for the impaired function of the knee musculature following muscle damage.