Combustion Waves on the Point Set Surface

This paper introduces a combustion model of heat transfer and fuel consumption for the propagation of a fire front on a point cloud surface. The heat transfer includes the heat advection by the airflow as well as diffusion, chemical reaction, and heat loss to generate complex, but controllable heat flows with a designed airflow velocity. For the stable heat advection, we solve a semi‐Lagrangian method on point samples using discrete exponential maps to trace the position from which the wind blows while preserving the geodesic distance. We also propose angular Voronoi weights for a discrete Laplace‐Beltrami operator that shows better isotropic diffusion on the inhomogeneous distribution of point clouds than the cotangent or moving least‐squares schemes. We demonstrate a diversity of burning scenarios by incorporating factors affecting the fire spreading such as buoyancy and object geometries in the airflow velocity fields, or by synthesizing patterns.     

The data warehouse virtualization framework for operational business intelligence

In order to explore the most current information and react faster to changing business conditions, organizations consider real‐time data warehousing a powerful technique to achieve operational business intelligence (BI). We propose in this paper a novel real‐time data warehouse (RTDW) framework based on the virtualization concept. Our approach introduces a conceptual modelling technique, known as ring modelling, for real‐time data management and multidimensional analysis. This technique produces a flexible semi‐structured data model that accommodates unknown business process data and relationships as they evolve, handles schema changes and aggregate‐management efficiently, and scales well with the large size of increasing data volumes. With the help of a telecommunication business example, We evaluated our proposed approach in an extensive experimental study where we compared our approach Ring Model with existing structured multidimensional conceptual models (MCMs), i.e. relational OLAP and multidimensional OLAP, and with semi‐structured MCM, i.e. XML Cubes, in terms of scalability, data storage estimations, data updates loading time, and query response times. Our performance results show that encouraging speedups are achieved.     

Practical stabilization of exponentially unstable linear systems subject to actuator saturation nonlinearity and disturbance

This paper investigates the problem of practical stabilization for linear systems subject to actuator saturation and input additive disturbance. Attention is restricted to systems with two anti‐stable modes. For such a system, a family of linear feedback laws is constructed that achieves semi‐global practical stabilization on the asymptotically null controllable region. This is in the sense that, for any set χ₀ in the interior of the asymptotically null controllable region, any (arbitrarily small) set χ_∞ containing the origin in its interior, and any (arbitrarily large) bound on the disturbance, there is a feedback law from the family such that any trajectory of the closed‐loop system enters and remains in the set χ_∞ in a finite time as long as it starts from the set χ₀. In proving the main results, the continuity and monotonicity of the domain of attraction for a class of second‐order systems are revealed. Copyright © 2001 John Wiley & Sons, Ltd.     

2,2,6,6‐Tetramethylpiperidine‐1‐oxyl‐mediated living mini‐emulsion polymerization of styrene under ambient pressure in a semi‐batch process: effect of ascorbic acid

2,2,6,6‐Tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated living mini‐emulsion polymerization of styrene with feeding of an ascorbic acid aqueous solution throughout the polymerization was performed at 90 °C under ambient pressure. The concentrations of sodium dodecylbenzenesulfonate (SDBS) and ascorbic acid were varied to study the shell polymerization mechanism of latex particles and evolution of growing chains. Interactions between SDBS and ascorbic acid and incompatibility between ascorbic acid and styrene were evident from UV‐visible analyses. High hydrophilicity of ascorbic acid in the aqueous phase was proved using a gravimetric method. Accordingly, the formation of a surface barrier on particles was proposed because of the interactions between SDBS and ascorbic acid. For higher SDBS concentration, the surface barrier on the particles was denser. Therefore, the polymerization rate decreased with increasing SDBS concentration. However, the polymerization rate increased with increasing ascorbic acid concentration. This was due to a higher consumption rate of TEMPO by ascorbic acid. Free TEMPO tended to reside in surface zones of the particles because of the surface activity between the aqueous and oil phases. The surface zones were thus the main loci where TEMPO was consumed by ascorbic acid. The estimated number‐average molecular weight (M_n) of growing chains increased in a linear fashion with conversion. This indicated that the growing chains were produced via living mini‐emulsion polymerization. For these growing chains, the estimated M_n and final polydispersity increased with increasing SDBS concentration. This was caused by a decrease in TEMPO concentration in the surface zones of particles with increasing SDBS concentration. The ‘livingness’ of polystyrene was identified by conducting bulk polymerization of chain extension. Based on the results obtained, a shell polymerization mechanism of latex particles was proposed, and living mini‐emulsion polymerization was limited to the surface zones of particles. Copyright © 2010 Society of Chemical Industry     

Absorption of ethylene from ethylene‐ethane gaseous mixture by AgNO3 solution in a semi‐continuous process

Ethylene absorption from an ethylene–ethane gaseous mixture in the silver nitrate solution is studied at different temperatures and concentrations. Unlike the previous studies, in which the absorption was studied by batch processes, a semi‐continuous process is applied in the present research. The results show that increase in temperature reduces the amount of absorbed ethylene and absorption time. The amount of absorbed ethylene is increased in solutions with higher concentrations of AgNO₃, whereas the mole ratio of absorbed ethylene per silver nitrate is decreased by increasing the AgNO₃ concentration. Total absorption is modelled as a function of the temperature and concentration of absorbing solution. The estimated values from the model are in good agreement with the experimental data.     

数值模拟在半因态金属加工中的应用

本文在综合有关半固态金属加工过程模拟文献资料的基础上，简要分析了半固金属加工过程模拟的特点，对数值模拟技术在半固态加工方面研究的发展，现状和趋势进行了详细的评述。     

Dehydrogenation of 11α‐hydroxy‐16α, 17‐epoxyprogesterone by encapsulated Arthrobacter simplex cells in an aqueous/organic solvent two‐liquid‐phase system

BACKGROUND: Arthrobacter simplex cells immobilised in sodium cellulose sulfate/poly‐dimethyl‐diallyl‐ammonium chloride microcapsules were used for the microbial dehydrogenation of 11α‐hydroxy‐16α,17‐epoxyprogesterone to 11α‐hydroxy‐16α,17α‐epoxypregn‐1,4‐diene‐3,20‐dione in an aqueous/organic solvent two‐liquid‐phase system, which is a key reaction in the production of glucocorticoid pharmaceuticals. The aim of the study was to establish a suitable aqueous/organic solvent two‐liquid‐phase system for performing semi‐continuous production in an airlift loop reactor by encapsulated A. simplex cells with the addition of suitable surfactants to achieve a higher yield of the product. RESULTS: n‐Hexane was selected as the most suitable organic solvent. In optimised Tween‐80 emulsion feed mode the conversion in the airlift loop reactor was as high as 97.54% when the time of reaction was 2 h, and the reaction time was greatly shortened. In semi‐continuous production the cultivation with immobilised cells was carried out for five batches in total. The conversion in each batch was above 95% and the enzymatic activity still remained quite high after five batches of biotransformation. CONCLUSION: The results showed that performing the conversion by this method shortened the reaction time and increased the productivity, thus demonstrating the great potential of the method for the dehydrogenation of 11α‐hydroxy‐16α,17‐epoxyprogesterone. Copyright © 2008 Society of Chemical Industry     

半封闭活塞式和螺杆式冷水机组性能分析

以两种产品为例，归纳了半封闭螺杆式和活塞式冷水机组的特点，分析了在不同冷水出水温度及不同制冷量情况下两种机组的性能，认为它们的制冷量、输入功率及COP值的变化趋势相近，但螺杆式冷水机组的COP值较活塞式的约高0.5.     

Hydrologic thresholds for riparian forest conservation in a regulated large Mediterranean river

Most riparian trees are phreatophytic, water table‐dependent plants which broadly differ in their tolerance to drought and permanent flooding. In semi‐arid settings, as water is limiting, inundations may be regarded as inputs rather than stresses for the survival of phreatophytes. In this study, the mortality rates and abundances of Populus alba, P. nigra, Salix alba and local Tamarix spp. were examined in 43 plots with different hydrologic conditions distributed across the floodplain of a large semi‐arid and Mediterranean river, the Ebro River (Spain). The objectives were to determine hydrologic thresholds for the maintenance of declining populations of those species, while providing novel information on their phreatophytic nature, and to examine shifts in the species composition along hydrologic gradients. All species exhibited significant relationships between mortality rates and hydrologic variables (deepest water table—WT, flood duration—FD and flood frequency—FF). S. alba was found to be the species with lowest tolerance to drier conditions (hydrologic thresholds for maintaining a mortality rate <50%: WT > ?1.22 m; FD: out of observation range; FF > 5.4 events y^?1), followed by P. nigra (WT > ?2.18 m; FD > 11.1%; FF > 3.8 events y^?1), Tamarix spp. (WT > ?2.96 m; FD > 3.7%; FF > 2.5 events y^?1) and P. alba (WT > ?3.45 m; FD > 1.7%; FF > 2.0 events y^?1). Only a significant reduction in S. alba relative abundance was observed as conditions got drier. The results provided quantitative information useful to guide management plans for the protection of Mediterranean phreatophytic tree species from further degradation and suggested that eventual natural or regulation‐induced droughts and groundwater declines would accelerate the loss of all phreatophytic species, especially S. alba. Copyright © 2010 John Wiley & Sons, Ltd.     

水电工程混凝土喷护方法的探讨

通过对干喷、湿喷、并列法喷护的剖析，针对其利弊开发出另一种介于干喷和半湿喷护方法，并对半湿喷护法的优缺点加以分析，探讨了半湿喷护法的工艺流程、喷嘴结构形式、水环结构及其效应。初步试验成果表明，半湿喷护法在技术上是可行的，经济效益也显著，可在逐步研究完善后推广应用。