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851.
塔河油田缝洞型油藏以溶洞、裂缝为主要储运空间,缝洞非均质性很强,其流体流动机理和含水率变化特征与一般砂岩油藏区别较大。基于管流理论建立了一种新的流动模型,并分别模拟了弹性开发和注水开发时缝洞型定容油藏的开发特征和含水率变化特点。该研究对于认识缝洞型油藏流体流动机理具有一定的借鉴意义。  相似文献   
852.
针对矿车铸件的生产工艺,大胆引进消失模工艺,通过实践及对生产过程的经验总结,为进一步完善提高生产技术和改进措施,扩大消失模工艺在其他产品的应用提出了意见。  相似文献   
853.
UV-Vis spectroscopy was used to directly determine the concentration of Eu(Ⅱ) during electroreduction of Eu(Ⅲ) in hydrochloric acid medium. Electroreduction was carried out in a flow type electrolyzer with glassy carbon cathode at the constant potential of -800 mV vs. Ag/AgCl. The effects of oxygen and concentration of hydrochloric acid on the system were investigated. For 0.01 mol·L-1 hydrochloric acid, calibration curves for Eu(Ⅱ) absorption bands at 248 and 320 nm were constructed. Molar absorption coefficients were estimated to be 2016 and 648 L·mol-1·cm-1, respectively. The absorbance strongly decreased with decrease in pH of the solution, whereas concentration of chloride had only a negligible effect.  相似文献   
854.
介绍柳钢质量管理系统的结构和功能以及存在问题,并提出改进措施。  相似文献   
855.
莱钢采用LD-LF-CC(方坯连铸)生产45^#钢铸坯质量存在较多问题,主要是表面气孔数量多、轧材顶锻裂纹等。从对顶锻裂纹缺陷进行金相分析、扫描电镜分析出发,研究45^#钢铸坯表面气孔形成的原因;生产实践中,通过采取控制钢中气体含量的措施,使45^#钢铸坯质量得到全面改善。  相似文献   
856.
Computational models have been used widely in tissue engineering research and have proven to be powerful tools for bio-mechanical analysis (i.e., blood flow, growth models, drug delivery, etc). This paper focuses on developing higher-fidelity models for vascular structures and blood vessels that integrate computational shape representations with biomedical properties and features. Previous work in computer-aided vascular modeling comes from two communities. For those in biomedical imaging, the goal of past research has been to develop image understanding techniques for the interpretation of x-ray, magnetic resonance imaging (MRI), or other radiological data. These representations are predominantly discrete shape models that are not tied to physiological properties. The other corpus of existing work comes from those interested in developing physiological models for vascular growth and behavior based on bio-medical attributes. These models usually either have a highly simplified shape representation, or lack one entirely. Further, neither of these representations are suitable for the kind of interactive modeling required by tissue engineering applications.This paper aims to bridge these two approaches and develop a set of mathematical tools and algorithms for feature-based representation and computer-aided modeling of vascular trees for use in computer-aided tissue engineering applications. The paper offers a multi-scale representation based on swept volumes and a feature-based representation that can attribute the geometric representation with information about blood flow, pressure, and other biomedical properties. The paper shows how the resulting representation can be used as part of an overall approach for designing and visualizing vascular scaffolds. As a real-world example, we show how this computational model can be used to develop a tissue scaffold for liver tissue engineering. Such scaffolds may prove useful in a number of biomedical applications, including the growth of replacement tissue grafts and in vitro study of the pharmacological affects of new drugs on tissue cultures.  相似文献   
857.
The recently developed high-order accurate multiple image approximation to the reaction field for a charge inside a dielectric sphere [J. Comput. Phys. 223 (2007) 846-864] is compared favorably to other commonly employed reaction field schemes. These methods are of particular interest because they are useful in the study of biological macromolecules by the Monte Carlo and Molecular Dynamics methods.  相似文献   
858.
The transformation of carbides with austenization time of a high speed steel (HSS) roll material, manufactured by a centrifugal casting method, has been studied. The correlation between wear resistance and the type, morphology, volume fraction, and distribution of the carbides has also been investigated. Microstructural observations, X-ray diffraction (XRD) analysis, hardness measurements, and energy dispersive spectroscopy (EDS) have been used to characterize the carbides. The type and volume fraction of carbides were found to change with austenizing time. During austenization, the transformation of the M3C carbides can be postulated as M3C + γ-Fe → M2C, with much finer nodular and rodlike MC carbides also forming through a solid-state transformation. The M2C carbide decomposes as M2C + γ-Fe → MC + M7C3 + M6C. The decomposed carbide substantially maintains a platelike shape until the end of decomposition. The most important finding of this study is that austenization results in changes in the type, morphology, volume fraction, and distribution of carbides and that it can be controlled to produced a homogeneous distribution of hard carbides, resulting in an improvement in the wear resistance of HSS rolls. This finding may be of great use for the industrial production of HSS rolls.  相似文献   
859.
主要介绍了土工布和膨润土防水毯(GCL)在垃圾卫生填埋场应用中的特点和作用,阐述了在卫生填埋场设计中选择土工布和GCL应注意的一些问题。  相似文献   
860.
卷取机前侧导板的作用是把带钢对准轧制中心线送入夹送辊,并在进入夹送辊时导板夹持带钢以减少钢卷的塔形。  相似文献   
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