Mechano-catalytic overall water splitting on some mixed oxides

Simple transition metal oxides such as NiO, Co₃O₄, Fe₃O₄ and Cu₂O were found to catalytically decompose water into H₂ and O₂ by mechanical energy. The reaction is regarded as “mechano-catalytic” overall water splitting” and is a quite novel catalytic reaction. In this paper, some general aspects on the mechano-catalytic overall water splitting are reviewed on simple oxides. In addition, recent results on the mechano-catalytic activity of a groups of mixed oxides, wolramite-type oxides with a formula of ABO₄ (A=Fe, Co, Ni and Cu, etc., B=W, Mo), are shown. AWO₄ (A=Fe, Co, Ni and Cu) decomposed water into H₂ and O₂ under the supply of mechanical energy, indicating that mechano-catalytic overall water splitting proceeded on wolframite-type compounds containing 3d-transition metals. AMoO₄ (A=Fe, Co, Ni) also decomposed water into H₂ and O₂ under supply of mechanical energy. The reaction properties on wolframite-type oxides are discussed.     

数模混合电路衬底耦合模型研究

提出了数模混合集成电路衬底耦合噪声的一种建模方案将集成电路芯片的衬底划分为多个Voronoi图,计算各区域的R、C值,在将衬底RC网络映射到原电路网表之后,对新网表进行SPICE模拟,分析数模混合集成电路中的衬底噪声.用此模型模拟了两个数模混合集成电路的衬底耦合噪声,指出了在模拟电路关键器件周围加保护环是减少衬底耦合噪声的一种有效途径.     

有分支天然气管线优化设计

管道系统的优化设计,即是寻求管径、壁厚、压气站数和输气压力等主要工艺参数的最佳组合,使系统在技术上可行经济上合理。考虑到天然气管道沿线 擀分气会导致各段管径、壁碍等设计参数的变化,同时根据技术经济学原理,引入终值费用作为管线的经济指标,建立优化模型,并 混合离散变量优化方法进行求解。算例实践证明该设计方法具有可行性     

适用于纯梁原油的天然混合羧酸盐ASP体系

胜利纯梁采油厂原油含蜡量高 ,凝固点高 ,地层渗透率低 ,粘土含量多 ,而且对碱敏感性高。以天然混合羧酸盐为主 ,通过正交实验设计和界面张力最低值测定获得针对纯梁采油厂的最佳三元复合驱配方 ,界面张力最低值为 5 .2× 10 -4 mN/m ,对此配方进行了室内模拟驱油实验研究 ,采收率提高达 14.6 %— 16 .7%OOIP。     

A criterion for brittle fracture in U-notched components under mixed mode loading

A failure criterion is proposed for brittle fracture in U-notched components under mixed-mode static loading. The criterion, called UMTS, is developed based on the maximum tangential stress criterion and also a criterion proposed in the past for mode I failure of rounded V-shaped notches [Gomez FJ, Elices M. A fracture criterion for blunted V-notched samples. Int J Fracture 2004;127:239-64]. Using the UMTS criterion, a set of fracture curves are derived in terms of the notch stress intensity factors. These curves can be used to predict the mixed mode fracture toughness and the crack initiation angle at the notch tip. An expression is also obtained from this criterion for predicting fracture toughness of U-notched components in pure mode II loading. It is shown that there is a good agreement between the results of UMTS criterion and the experimental data obtained by other authors from three-point bend specimens.     

Adsorption kinetics and isotherm of anionic dyes onto organo-bentonite from single and multisolute systems

The performances of polydiallydimethylammonium modified bentonite (PDADMA–bentonite) as an adsorbent to remove anionic dyes, namely Acid Scarlet GR (AS-GR), Acid Turquoise Blue 2G (ATB-2G) and Indigo Carmine (IC), were investigated in single, binary and ternary dye systems. In adsorption from single dye solutions with initial concentration of 100 μmol/L, the dosage of PDADMA–bentonite needed to remove 95% dye was 0.42, 0.68 and 0.75 g/L for AS-GR, ATB-2G and IC, respectively. The adsorption isotherms of the three dyes obeyed the Langmuir isotherm model with the equilibrium constants of 0.372, 0.629 and 4.31 L/μmol, the saturation adsorption amount of 176.3, 149.2 and 228.7 μmol/g for ATB-2G, IC and AS-GR, respectively. In adsorption from mixed dye solutions, the isotherm of each individual dye followed an expanded Langmuir isotherm model and the relationship between the total amount of dyes adsorbed and the total equilibrium dye concentration was interpreted well by Langmuir isotherm model. In the region of insufficient dosage of PDADMA–bentonite, the dye with a larger affinity was preferentially removed by adsorption. Desorption was observed in the kinetic curve of the dye with lower affinity on PDADMA–bentonite surface by the competitive adsorption. The kinetics in single dye solution and the total adsorption of dyes in binary and ternary dye systems nicely followed pseudo-second-order kinetic model.     

An investigation into the mechanics of cutting using data from orthogonally cutting Nylon 66

Cutting force data for Nylon 66 has been examined in terms of various different models of cutting. Theory that includes significant work of separation at the tool tip was found to give the best correlation with experimental data over a wide range of rake angles for derived primary shear plane angle. A fracture toughness parameter was used as the measure of the specific work of separation. Variation in toughness with rake angle determined from cutting is postulated to be caused by mixed mode separation at the tool tip. A rule of mixtures using independently determined values of toughness in tension (mode I) and shear (mode II) is found to describe well the variation with rake angle. The ratio of modes varies with rake angle and, in turn, with the primary shear plane angle. Previous suggestions that cutting is a means of experimentally determining fracture toughness are now seen to be extended to identify the mode of fracture toughness as well.     

Crack growth prediction and non-linear analysis for an elasto-plastic solid

In this paper, a variable radius for the plastic zone is introduced and a maximum principal stress criterion is proposed for the prediction of crack initiation and growth. It is assumed that the direction of crack initiation coincides with the direction of the maximum principal stress. The von Mises yield criterion is applied to define the plastic zone, instead of assuming a plastic zone with a constant distance r from the crack tip. An improvement is made to this fracture criterion, and the criterion is extended to study the crack growth characteristics of mixed mode cracks. Based on the concept of frictional stress intensity factor, k_f, the rate of fatigue crack propagation, db/dN, is postulated to be a function of the effective stress intensity factor range, Δk_eff. Subsequently, this concept is applied to predict crack growth due to fatigue loads. The proposed crack growth model is discussed by comparing the experimental results with those obtained using the maximum principal stress criterion.     

Fermentative biohydrogen production by mixed anaerobic consortia: Impact of glucose to xylose ratio

Glucose and xylose are the dominant monomeric carbohydrates present in agricultural materials which can be used as potential building blocks for various biotechnological products including biofuels production. Hence, the imperative role of glucose to xylose ratio on fermentative biohydrogen production by mixed anaerobic consortia was investigated. Microbial catabolic H₂ and VFA production studies revealed that xylose is a preferred carbon source compared to glucose when used individually. A maximum of 1550 and 1650 ml of cumulative H₂ production was observed with supplementation of glucose and xylose at a concentration of 5.5 and 5.0 g L⁻¹, respectively. A triphasic pattern of H₂ production was observed only with studied xylose concentration range. pH impact data revealed effective H₂ production at pH 6.0 and 6.5 with xylose and glucose as carbon sources, respectively. Co-substrate related biohydrogen fermentation studies indicated that glucose to xylose ratio influence H₂ and as well as VFA production. An optimum cumulative H₂ production of 1900 ml for 5 g L⁻¹ substrate was noticed with fermentation medium supplemented with glucose to xylose ratio of 2:3 at pH 6. Overall, biohydrogen producing microbial consortia developed from buffalo dung could be more effective for H₂ production from lignocellulosic hydrolysates however; maintenance of glucose to xylose ratio, inoculum concentration and medium pH would be essential requirements.