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991.
Molecular dynamical simulation has been carried out to investigate the structure and dynamics of a dipolar fluid under strong shear. Dipolar fluid consists of polarizable particles, which have an induced dipole moment in the applied field direction. Shear stress is perpendicular to the field direction. When shear stress is small, the flow has a flowing-chain structure. If shear stress increases to pass a critical value, flowing-chain structure changes to flowing layer structure. Each layer is parallel to the flow direction and shear direction. Within one layer, particles form strings in the flow direction.  相似文献   
992.
Comparative analysis of urban reflectance and surface temperature   总被引:1,自引:0,他引:1  
Urban environmental conditions are strongly dependent on the biophysical properties and radiant thermal field of the land cover elements in the urban mosaic. Observations of urban reflectance and surface temperature provide valuable constraints on the physical properties that are determinants of mass and energy fluxes in the urban environment. Consistencies in the covariation of surface temperature with reflectance properties can be parameterized to represent characteristics of the surface energy flux associated with different land covers and physical conditions. Linear mixture models can accurately represent Landsat ETM+ reflectances as fractions of generic spectral endmembers that correspond to land surface materials with distinct physical properties. Modeling heterogeneous land cover as mixtures of rock and/or soil Substrate, Vegetation and non-reflective Dark surface (SVD) generic endmembers makes it possible to quantify the dependence of aggregate surface temperature on the relative abundance of each physical component of the land cover, thereby distinguishing the effects of vegetation abundance, soil exposure, albedo and shadowing. Comparing these covariations in a wide variety of urban settings and physical environments provides a more robust indication of the global variability in these parameter spaces than could be inferred from a single study area. A comparative analysis of 24 urban areas and their non-urban peripheries illustrates the variability in the urban thermal fields and its dependence on biophysical land surface components. Contrary to expectation, moderate resolution intra-urban variations in surface temperature are generally as large as regional surface heat island signatures in these urban areas. Many of the non-temperate urban areas did not have surface heat island signatures at all. However, the multivariate distributions of surface temperature and generic endmember fractions reveal consistent patterns of thermal fraction covariation resulting from land cover characteristics. The Thermal-Vegetation (TV) fraction space illustrates the considerable variability in the well-known inverse correlation between surface temperature and vegetation fraction at moderate (< 100 m) spatial resolutions. The Thermal-Substrate (TS) fraction space reveals energetic thresholds where competing effects of albedo, illumination and soil moisture determine the covariation of maximum and minimum temperature with illuminated substrate fraction. The dark surface endmember fraction represents a fundamental ambiguity in the radiance signal because it can correspond to either absorptive (e.g. low albedo asphalt), transmissive (e.g. deep clear water) or shadowed (e.g. tree canopy shadow) surfaces. However, in areas where dark surface composition can be inferred from spatial context, the different responses of these surfaces may still allow them to be distinguished in the thermal fraction space.  相似文献   
993.
A plasma discharge initiation system for the explosive volumetric combustion charge was designed, investigated and developed for practical application. Laboratory scale experiments were carried out before conducting the large scale field tests. The resultant explosions gave rise to less noise, insignificant seismic vibrations and good specific explosive consumption for rock blasting. Importantly, the technique was found to be safe and environmentally friendly.  相似文献   
994.
杨力  莫文杰  向臻锋 《山西建筑》2007,33(33):140-141
堆载预压过程中,进行相应的稳定分析对于控制加载速率、确定加载高度是必须进行的一项工作,采用有限单元法对此进行了探讨,详细阐述了有限元理论分析边坡稳定的几种重要因素,并考虑分步堆载的特点,模拟堆载过程,具有一定的工程实际意义。  相似文献   
995.
A new approach for the estimation and the validation of a structural equation model with a formative-reflective scheme is presented. The basis of the paper is a proposal for overcoming a potential deficiency of PLS path modeling. In the PLS approach the reflective scheme assumed for the endogenous latent variables (LVs) is inverted; moreover, the model errors are not explicitly taken into account for the estimation of the endogenous LVs. The proposed approach utilizes all the relevant information in the formative manifest variables (MVs) providing solutions which respect the causal structure of the model. The estimation procedure is based on the optimization of the redundancy criterion. The new approach, entitled redundancy analysis approach to path modeling (RA-PM) is compared with both traditional PLS Path Modeling and LISREL methodology, on the basis of real and simulated data.  相似文献   
996.
In this paper, a new image analysis based method for electrospun nanofiber diameter measurement has been presented. The method was tested by a simulated image with known characteristics and a real web. Mean (M) and standard deviation (STD) of fiber diameter obtained using this method for the simulated image were 15.02 and 4.80 pixels respectively, compared to the true values of 15.35 and 4.47 pixels. For the real web, applying the method resulted in M and STD of 324 and 50.4 nm which are extremely close to the values of 319 and 42 nm obtained using manual method. The results show that this approach is successful in making fast, accurate automated measurements of electrospun fiber diameters.  相似文献   
997.
高层建筑结构设计特点与剪力墙设计   总被引:6,自引:0,他引:6  
夏卓文 《住宅科技》2007,27(2):29-32
围绕高层建筑结构,总结了高层建筑结构设计的特点,提出了剪力墙设计的几个问题,以及高层建筑结构分析和各种体系相对应的方法。  相似文献   
998.
999.
简要介绍了一种用于维弹道修正引信的执行机构。通过数学模型,结合MDT三机械设计软件和Working Model动力学仿真软件,对机构的受力情况和工作过程进行了数字仿真和系统分析,并通过对飞行弹道的模拟,得出了一维时间控制射程修正规律。  相似文献   
1000.
徐巧明  高清  韩仿  夏冰 《现代农药》2002,1(4):17-18
本文采用高效液相色谱法,以乙腈+水(60+40)作为流动相,使用C18柱,在同一条件下,同时成功地测定出20%乙·苄可湿性粉剂中的二元有效成份含量。该方法快速准确,乙草胺测定方法的相关系数为0.99986,平均回收率99.2%,苄黄隆测定方法的相关系数为0.99996,平均回收率为99.5%。  相似文献   
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