Structural analysis of Aleksinac oil shale kerogen by high-resolution solid-state C n.m.r. spectroscopy

A sample of kerogen from Aleksinac oil shale was examined by high-resolution solid-state ¹³C n.m.r. spectroscopy. The presence and relative proportions of kerogen structural units were estimated using a combination of NQS and T_1C methods with a peak-synthesis technique applied to the ¹³C CP—MAS spectrum. Relaxation parameters from these experiments were used to estimate differences in relative ‘mobility’ of various structural units. The kerogen was found to be highly aliphatic and to contain 79% long-chain aliphatic plus alicyclic structures, as well as 9% aromatic structures. These findings are in good agreement with the characterization of the same kerogen from its oxidation products.     

Stabilization of PCC dispersions prepared directly in the mother-liquid after synthesis through the carbonation of (hydrated) lime

Various CaCO₃-based products are often used in the form of concentrated aqueous dispersions. This study investigates the stabilization of PCC dispersions prepared directly in the mother-liquid after the carbonation of (hydrated) lime through the adsorption of a commercial sodium polyacrylate dispersant. The results demonstrate that the composition of the mother-liquid, particularly the Ca²⁺ activity, profoundly influences virtually all processes pertinent to dispersion stabilization—from the initial charging of the CaCO₃ surface in base PCC dispersions, to the surface charge regulation and dispersion stabilization efficiency of the polyacrylate dispersing agent. Rising prominence of the counterion condensation effects in Ca²⁺ rich solutions limits the conditions conducive to the surface charge regulation through dispersant adsorption to an optimum pH range of about 8-11. Furthermore, dispersion stability analysis, based on the classical DLVO theory of colloid stability, and corroborated by experimental evidence in the form of particle size distribution analyses, also indicates that optimum stability conditions for such PCC dispersions are established with small dispersant doses (0.25-0.5% per dry weight) in the pH range of about 9-11.     

PDM型立磨在矿渣粉磨中的应用

针对目前球磨机粉磨超细矿渣的缺点，本文探讨使用PDM型立磨来生产超细矿渣。研究表明，经过改造的立磨－－PDM型立磨生产的超细矿渣的粒度、活性系数等性能均与球磨机粉磨的矿渣相当，但立磨的电耗、磨损远小于球磨。     

添加石英对莫来石－刚玉制品结构的影响

探讨了引入石英颗粒的莫来石－刚玉制品中大气孔的成因。认为与液相的生成及其在毛细管力作用下的转移有关；与莫来石生成膨胀效应对颗粒拉紧的阻碍有关；与石英相交所引起的体积膨胀有关。     

Activities of MFI-Supported Rhenium Catalysts for the Aromatization of Methane: Effect of Cationic Form of the Inorganic Carrier

MFI type inorganic carrier was used in two different cationic forms, hydrogen and calcium respectively. MFI-supported molybdenum and rhenium catalysts were prepared. The activities of the catalysts were compared for the aromatization reaction of methane. Higher activity values were attained with the catalysts supported on HZSM-5. Aromatics were also observed with the catalysts supported on CaZSM-5, despite their deficiency in acid sites. Highly dispersed rhenium is expected to be formed with the use of the inorganic carrier in calcium form. On the other hand, lower reaction rates were observed with rhenium supported on CaZSM-5, in spite of the improved dispersion of the active rhenium species on this catalyst. This was interpreted in terms of the critical role of the acid sites in the conversion of methane to aromatics, compared to the improved dispersion of the active metal.     

Large-scale SRAM-based IP lookup architectures using compact trie search structures

SRAM-based pipelined architectures for high-speed IP lookup using Field Programmable Gate Arrays (FPGAs) has recently attracted a great deal of attention from researchers. Due to the limited amount of on-chip memory and the number of I/O pins of FPGAs, compact data structures providing high memory efficiency are in great demand.     

Feedback control for multi-resource usage of virtualised database server

Virtualisation and cloud computing have recently received significant attention. Resource allocation and control of multiple resource usages among virtual machines in virtualised data centres remains an open problem. Therefore, in this paper, our focus is to control CPU (central processing unit) usage and memory consumption of a virtual database machine in a data centre under a time-varying heavy workload. In addition to existing work, we attempt to control multiple outputs, such as the CPU usage and memory consumption of a virtualised database server (DBVM), via changing multiple server parameters, such as the CPU allocation and memory allocation, in real time. We indicated that a virtualised database server might be modelled as a linear time-unvarying system. We obtained and compared both MIMO (multi input–multi output) and multiple SISO (single input–single output) models of that system. We designed multiple SISO feedback controllers to achieve desired CPU usages and memory consumptions under workload.     

Scalable Realistic Rendering with Many‐Light Methods

Recent years have seen increasing attention and significant progress in many‐light rendering, a class of methods for efficient computation of global illumination. The many‐light formulation offers a unified mathematical framework for the problem reducing the full lighting transport simulation to the calculation of the direct illumination from many virtual light sources. These methods are unrivaled in their scalability: they are able to produce plausible images in a fraction of a second but also converge to the full solution over time. In this state‐of‐the‐art report, we give an easy‐to‐follow, introductory tutorial of the many‐light theory; provide a comprehensive, unified survey of the topic with a comparison of the main algorithms; discuss limitations regarding materials and light transport phenomena and present a vision to motivate and guide future research. We will cover both the fundamental concepts as well as improvements, extensions and applications of many‐light rendering.     

对二位六通事故配压阀油路切换的探讨

通过对平班水电站两种不同油路切换方式的事故配压阀的结构分析以及在极端情况下两种不同油路切换方式所造成的影响,探讨了两种不同油路切换方式的事故配压阀的优劣。     

The determination of molecular weights of polymers from critical concentrations of ternary systems polymer-polymer-solvent

The dependence of the critical concentration of the ternary system polymer-polymer-solvent on the molecular weight can be expressed by the relation where c_c is the critical concentration, M? the appropriate average of the molecular weight of both polymers; A and c_c∞ are constants for the given system. The possibility of determining the molecular weight of one of the polymers from the value c_c and the molecular weight of the known polymer with the aid of equation (1) is discussed.