大朝山水电站地下洞室安全监测资料分析

大朝山水电站引水发电系统为地下工程，根据各项安全监测物理量的主要观测成果，对最大观测值分析其对工程的安全影响，为保证其安全运行具有重要意义。为此，分别对大朝山水电站的主要地下建筑物，包括压力引水隧洞、地下厂房、尾水调压室的最大观测值进行了分析研究，并提出了一些建议，有较大的参考价值。     

明渠断面水流流速与边界剪切应力横向分布模型

天然河流的横断面多为由主槽和漫滩组成的复式断面,水流在这种断面中比在单一断面中受到更多因素影响,流态也更加复杂。通过将明渠横断面上微元体在水流方向的N-S控制方程沿水深积分,得出描述垂线平均流速和边界剪切应力横向分布的模型,并通过对实验数据的验证,确定了模型的实用性。     

最值求解技巧:巧变四数

在用基本不等式求最值时,大家都熟悉一个口诀:"一正二定三相等",但是有许多学生在怎样保证定值和相等时不知道该如何变形.为了解决学生的困难和困惑,我根据自己的经验,概括为两句口诀:"一正二定三相等,巧变四数定乾坤".     

The Effect of the Estimation on Goodness‐of‐Fit Tests in Time Series Models

Abstract. We analyze, by simulation, the finite‐sample properties of goodness‐of‐fit tests based on residual autocorrelation coefficients (simple and partial) obtained using different estimators frequently used in the analysis of autoregressive moving‐average time‐series models. The estimators considered are unconditional least squares, maximum likelihood and conditional least squares. The results suggest that although the tests based on these estimators are asymptotically equivalent for particular models and parameter values, their sampling properties for samples of the size commonly found in economic applications can differ substantially, because of differences in both finite‐sample estimation efficiencies and residual regeneration methods.     

浅谈界河倒虹吸预应力混凝土裂缝的预控措施

文章在通过对混凝土裂缝产生的原因进行分析的基础上,阐述了对在界河倒虹吸施工中预应力混凝土裂缝所采取的预控措施。     

川西低渗气藏单井地应力计算方法综合研究

四川盆地新场气田是一个低孔低渗的裂缝性砂岩气田，储层物性差，自然产能低，需经压裂后才能投产，压裂后气井增加的产能与压裂的效果密切相关。提前认识储层当前地应力的特征，有助于压裂设计时确定裂缝产状、缝长、缝宽等参数，减少储层水力压裂改造的盲目性，降低中、低渗透油气田开发的风险。通过大量测井资料的计算，确定了新场气田储层地应力的大小和方向，并综合采用微地震测量、岩石声发射资料、古地磁等岩心测试资料和水力压裂等多种方法进行交互验证，各种方法求得的地应力特征十分相近，说明利用测井资料求取储集层地应力原理简单，计算结果符合实际的地应力特征，是一种低风险研究计算储层地应力特征的方法，可以用于指导低渗透油气田的井网部署和储层的单井压裂改造。     

Effects of hot-carrier stress on high performance polycrystalline silicon thin film transistor with a single perpendicular grain boundary

This paper is a report on the effect of a single perpendicular grain boundary on the hot-carrier and high current stability in high performance polycrystalline silicon (poly-Si) thin film transistors (TFTs). Under a hot carrier stress condition (Vg = Vth + 1 V, Vd = 12 V), the poly-Si TFT with a single grain boundary is superior to the poly-Si without any grain boundary because of the smaller free carriers available for electric conduction. The shift of transconductance in poly-Si TFT with a single grain boundary is less than 5% after hot carrier stress during a period of 1000 s. The shift of transconductance is about 25% in the case of the poly-Si TFTs without a grain boundary in the channel. On high current stress, the poly-Si TFT without the grain boundary is less degraded than the poly-Si TFT with the grain boundary because the concentrated electric field near the drain junction is lower.     

Modelling of Diffuse Interfaces with Temperature Gradients

The work is devoted to capillary phenomena in miscible liquids under the assumption that they have a constant and the same density. The model consists of the heat equation, diffusion equation, and the Navier-Stokes equations with the Korteweg stress. We study several configurations corresponding to the microgravity experiments planned for the International Space Station. The basic conclusion of the numerical simulations is that transient capillary phenomena in miscible liquids exist and can produce convective flows sufficiently strong to be observed experimentally. In particular, there exists a miscible analogue to the Marangoni convection where the temperature gradient is applied along the transition zone between two fluids. Convection also appears if, instead of the temperature gradient, the case where the width of the transition zone varies in space is considered. Finally, similar to the immiscible case, miscible drops move in a temperature gradient.     

Perceived stress management skill mediates the relationship between optimism and positive mood following radical prostatectomy.

This study evaluated relations among optimism, perceived stress management skills (PSMS), and positive mood in 46 men who had surgical treatment for localized prostate cancer. The authors found that optimism, PSMS, and positive mood scores were positively correlated. Positive mood was unrelated to demographic and disease-related control variables. In a hierarchical regression model controlling for PSMS, the relationship between optimism and positive mood became nonsignificant, whereas PSMS remained a correlate of positive mood. Results suggest that the relationship between optimism and positive mood may be mediated by belief in being able to use stress management techniques effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eigenspannungen als Messgröße zur Qualitätssicherung

Residual stress as measured quantity in quality assurance The x‐ray method is used in the Volkswagen Automotive Group at different world‐wide locations as a standard procedure to determine residual stress. As an important measured quantity in the quality assurance residual stresses are specified in drawings of different components (e.g. gears, coil springs). Measurements are carried out during quality assurance, production, damage analyse, technical development department and design control of components from suppliers. An optimum efficiency can be achieved, if it exists a unique correlation between residual stress values and loading capacity of components, and if the processes to introduce residual stress can be optimized using residual stress measurements during the production.