旋转管式膜分离器内流体的剪切力分布

推导了稳流下旋转管式膜器环隙间流体的轴向和径向速度，得出切向和轴向剪切力解析式以及剪切力分布曲线。在非稳流下，采用函数拟合法，得出流体切向速度随半径变化的表达式及流体所受切向剪切力和分布曲线。运用端流理论，分别讨论了水力光滑膜器内和水力粗糙膜器内轴向湍流的速度分布，得出了轴向剪切力的表达式及分布曲线。     

层间接触对环氧沥青混凝土复合道面结构性能的影响

为了探究环氧沥青混凝土加铺层这种快速、有效的机场道面修建技术,利用ANSYS有限元程序,基于足尺多板体系,考虑了结构层之间不同的接触状态以及旧道面板之间的传荷能力,对复合道面结构层间受力状态进行了分析,结果表明:旧水泥混凝土道面板与基础之间的接触状况对加铺层弯沉影响略大,环氧沥青混凝土与旧水泥混凝土道面板之间的接触状况对复合道面结构应力指标影响明显,增强加铺层界面粘结强度能够改善复合道面结构受力状态,因此,在进行加铺层设计时要考虑选取合理的层间接触状态。     

城区屋面雨水径流水文水质特征研究

研究城区屋面径流水文过程与污染物浓度变化特征,为有效利用城市雨水、控制非点源污染提供依据。通过体积法对新乡市城区屋面降雨径流进行采样,水质指标分析包括pH、SS、COD和DO。屋面径流系数为0.92~0.98间。研究结果表明:径流初期污染严重,后期COD、SS浓度分别在25 mg/L和30 mg/L以下。径流曲线形态与降雨过程线类似,两者波动幅度相对较小。径流中COD与SS之间的相关性较好,而DO与其之间的相关性较差。径流水质主要受降雨量、降雨强度、屋面材料、季节和气温等因素影响。     

凸显科学思维训练的计算机网络原理课程教学改革

科学思维是人类获得和发现知识的基本思维方法。在教学活动中,将知识传授与科学思维训练有机结合起来,对于增强学生的学习积极性和主动性、提升人才培养质量都是有益的。本文从教学方法改革、教学内容优化、教学实施环节、教学条件建设等方面介绍了在计算机网络原理课程中开展科学思维训练的基本做法和经验,分析了科学思维训练与专业知识学习之间的关系,指出了在课程教学中开展科学思维训练有待解决的问题。     

Fatigue behaviors of Z2CND18.12N stainless steel under thermal-mechanical cycling

Tests under mechanical strain control were performed to investigate the TMF behavior of Z2CND18.12N within the temperature range between 150–550 ? C. Different strain amplitudes and phase-angles were applied. Total strain controlled low cycle fatigue test was also performed at the peak temperature of TMF cycling. The results show that the cyclic stress response of the material displayed an initial hardening regime followed by a saturation period and then cyclic softening till failure. The TMF cycling leads to the development of significant amounts of mean stress. Some life prediction models were employed to predict the TMF life of Z2CND18.12N, and the results indicate that the energy-based models provide good prediction on the thermal-mechanical fatigue behaviors of this material. An optical microscopic observation shows that the surface crack initiations and crack propagations are typically transgranular mode.     

Langmuir Probe Measurements of an Expanding Argon Plasma

In this work,we studied the effects of the discharge current,gas flow rate and vessel pressure on the electron temperature and density of Ar plasma by Langmuir probe measurement.The argon plasma was created by a one-cathode arc source.The experimental results show that with increasing discharge current and gas flow rate,the electron temperature and density increase.It is found that when the discharge current is 70 A,90 A and HO A at an argon flow rate of2000 seem,the electron densities at about 0.186 m distance from the nozzle are 13.00×10~(18) m~(-3),14.04×10~(18) m~(-3) and 15.62×10~(18) m~(-3),and the electron temperatures are 0.38 eV,0.58 eV and0.71 eV,respectively.The positive I-V characteristic is explained.