Marching Cubes算法改进研究及应用

对MC算法进行了改进和优化,运用渐近线判别法解决了原有算法的二义性问题,改善了生成图形的质量;利用线性八叉树结构提高了图形的绘制速度,使实时绘制和交互操作成为可能。运用改进后的MC算法,结合某铁矿实测数据进行矿体表面三维重构,得到了满意的效果。     

基于Max-tree的连通区域标记新算法

采用灰度图像创建Maxtree的基本思想,提出一种新的二值图像连通区域标记算法。该算法主要采用8邻域搜索及排序队列方式实现,通过一次扫描二值图像即可完成连通区域标记。提出一种新的8邻域搜索策略,可以将邻域搜索次数由八次减少到平均四次以下,从而提高了系统效率。此外,还给出一种排序队列的快速实现方法,并将其应用到标记算法中。而且,该算法的运行时间仅与待标记图像的大小有关,与连通区数目和图像内容无关。该算法已应用于海藻图像识别,实验结果表明该算法是快速、高效的。     

Relative expression and regulation by short-term fasting of lysophosphatidic acid receptors and autotaxin in white and brown adipose tissue depots

Lysophosphatidic acid (lysoPtdOH) levels have previously been reported to decrease in rodents with short-term fasting. We investigated whether a 16 h fast would change expression of autotaxin, the predominant phospholipase D responsible for adipose-derived lysoPtdOH synthesis, or any of the lysophosphatidic acid receptors (1–6) in four white adipose tissue (WAT) depots and interscapular brown adipose tissue (BAT) in male C57Bl/6J mice fed ad libitum, or fasted for 16 h. Aside from small inductions of Lpar1 in epididymal WAT and Lpar2 in epididymal and inguinal WAT, no significant changes were observed in expression of the Lpar family members, or autotaxin in perirenal, retroperitoneal, epididymal, or inguinal WAT or BAT with fasting. Comparison of the relative expression of Lpar1-6 in various depots showed that Lpar6 was the predominant Lpar in both WAT and BAT, and suggests that further work on the adipose-specific role of Lpar6 is warranted.     

Comparison of two low-hazard organic solvents as individual and cosolvents for the fabrication of polysulfone membranes

Petroleum-derived solvents commonly used in membrane fabrication are often hazardous and toxic, so the investigation of safer alternatives is important. In this study, two low-hazard solvents, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate (Rhodiasolv® PolarClean) and gamma-valerolactone (GVL), were investigated as sole solvents and as cosolvents to cast polysulfone membranes via nonsolvent induced phase inversion. Normalized viscosity was introduced as an indicator of dope solution homogeneity and was used to compare the required time of mixing to achieve full dissolution of the polymer in the different solvents/solvent mixtures. All dope solutions made with low-hazard solvents were found to be more viscous than those made with traditional solvents, which meant additional mixing time was needed, and that fabricated membranes were morphologically different. With respect to operation, membranes cast from dope solutions containing equal amounts of PolarClean and GVL displayed the most similar flux curves and solute rejection to those made using the traditional solvent tested.     

The grain-boundary resistance of CeO2 ceramics: A combined microscopy-spectroscopy-simulation study of a dilute solution

Weakly acceptor-doped ceria ceramics were characterized structurally and compositionally with advanced transmission electron microscopy (TEM) techniques and electrically with electrochemical impedance spectroscopy (EIS). The grain boundaries studied with TEM were found to be free of second phases. The impedance spectra, acquired in the range 703 ≤ T/K ≤ 893 in air, showed several arcs that were analyzed in terms of bulk, grain-boundary, and electrode responses. We ascribed the grain-boundary resistance to the presence of space-charge layers. Continuum-level simulations were used to calculate charge-carrier distributions (of acceptor cations, oxygen vacancies, and electrons) in these space-charge layers. The acceptor cations were assumed to be mobile at high (sintering) temperatures but immobile at the temperatures of the EIS measurements. Space-charge formation was assumed to be driven by the segregation of oxygen vacancies to the grain-boundary core. Comparisons of data from the simulations and from the EIS measurements yielded space-charge potentials and the segregation energy of vacancies to the grain-boundary core. The space-charge potentials from the simulations are compared with values obtained by applying the standard, analytical (Mott–Schottky and Gouy–Chapman) expressions. The importance of modelling space-charge layers from the thermodynamic level is demonstrated.     

Solubility parameter estimation and phase inversion modeling of bentonite-doped polymeric membrane systems

Effects of bentonite concentration on morphology and permeation characteristics of bentonite-doped polysulfone membranes were investigated. Solubility sphere for bentonite was constructed to estimate its solubility parameter. Thermodynamic modeling of phase inversion of this system was carried out using Flory–Huggins theory. The trade-off between thermodynamic and kinetic parameters was used to predict the membrane morphology for bentonite concentration varying from 0 to 5 wt %. The porosity of bentonite-doped membranes decreased up to 3 wt % that increased thereafter. Morphological analysis showed dense cross section with finger-like macrovoids at 3 wt % beyond which it changed to honeycomb structure with large circular voids. Permeability of 3 wt % membrane was the lowest (5.6 × 10⁻¹² m/Pa s) with 95% bovine serum albumin rejection. Contact angle of the membranes decreased from 83 to 66° with bentonite addition making the membrane more hydrophilic. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48450.     

基于ANSYS Workbench柱塞泵主轴动、静态性能分析

主轴是液压泵的重要零件之一,起着传递扭矩的作用,对液压泵的性能有着重要的影响。运用ANSYS Workbench对某型开式回路斜盘式柱塞变量泵的主轴进行动、静态性能分析,主要对柱塞泵主轴进行静力分析和模态分析,得到相关参数,并对主轴进行了一定的优化。为该类主轴的设计和优化提供一定的参考。     

Lubrication modes and the IRG transition diagram

The relationship between a Lubrication Mode Diagram (LMD) for concentrated contacts (LCC's) and the ‘IRG transition’ diagram has been studied. In addition, scuffing results, obtained by the IRG (International Research Group) have been analysed, as well as the results of scuffing tests performed by different workers using a two-disc apparatus. It has been found that in Region I of the IRG transition diagram, three sub-regions can be distinguished, representing elastohydrodynamic lubrication, mixed lubrication, and boundary lubrication, respectively. Thus, the IRG transition diagram is not comparable to a ‘lubrication mode diagram’. Furthermore, it has been found that failure of LCC's by scuffing most frequently occurs under conditions of mixed lubrication. Therefore, scuffing criteria based upon the assumption that the load at failure is carried entirely by the micro-contacts are doubtful, and probably wrong.     

Estimation of the effects of an intensive solar intervention in the historical centre of jaén (Spain)

This paper is directed at evaluating the theoretical potential of an intensive solar intervention in the historical centre of the city of Jaén (Spain). Using the outputs of a solar intervention proposal comprising biomass, photovoltaics and solar thermal domestic hot water (DHW) over a 50-building sample (in which those suitable for solar measures have been selected by evaluating each one over a collection of parameters), energy savings, environmental benefits and economic aspects of the envisaged actions are extrapolated over the entire historical centre. A saving of about 70% of conventional source energy annual consumption and a decrease of some 70% and 73% of CO₂ and SO_x annual releases, respectively, could be reached with respect to the present situation. Besides, an amount of conventionally generated electricity equivalent to the yearly photovoltaic-generated electricity would require 131500 m³ of water a year, which is a rather significant feature for a dry climate like that of the city. the unitary cost of energy in the new scenario would be 60.7 pta kWh-¹ for photovoltaics, 329.9 pta m-³ for DHW using solar thermal installations and 4.6 Pta kWh-¹ for biomass heating (1 US$ = 132.7 pta; 1 ECU = 160.9 pta).