电压互感器二次中心线接地方式的分析和改进

分析了电压互感器二次回路中心线电压产生漂移的原因，指出了现有的回路在某些特殊故障情况下的隐患，提出了中心线接线的改进方法和建议。     

S‐N curves in the very‐high‐cycle fatigue regime: statistical modeling based on the hydrogen embrittlement consideration

The continuous increment of durability and reliability requirements for many machinery components is significantly enhancing the research activity in the Very‐High‐Cycle Fatigue (VHCF) characterization of metallic materials, in particular of high‐strength steels for critical structural applications. According to the model, the VHCF strength of high‐strength steels can be estimated from the projected area of the ‘Optically Dark Area’ (ODA), which plays a key role in the VHCF response of high‐strength steels: more than 95% of the total VHCF life is consumed in the ODA formation, with crack growing even though the Stress Intensity Factor (SIF) is below the threshold for crack growth. Following the hydrogen embrittlement theory proposed by Murakami, hydrogen is supposed to assist crack growth within the ODA. The present paper proposes a general SIF formulation for the analytical model of the hydrogen assisted crack growth within the ODA. Starting from the general SIF formulation, a general expression for the material fatigue limit is obtained in the paper. The statistical method for the estimation of the parameters involved in the proposed model is finally illustrated in the paper and numerically applied to an experimental dataset.     

Apparent Molar Volumes of N,N – Disubstituted Monoamides: A Convenient Tool to Interpret Iron(Iii) Extraction Profiles from Hydrochloric Acid Solutions

New iron(III) extraction data involving two N,N-disubstituted monoamides, N-ethyl-N-phenyloctanamide (EPHOA) and N-ethyl-N-cyclohexyloctanamide (ECHOA), from hydrochloric acid media, are presented and discussed. These, and earlier results obtained with other similar N,N-disubstituted monoamides, are interpreted in this work through their apparent molar volumes in 1,2-dichloroethane, and all the information is being used to screen for solute-solute and solute-diluent interactions. The results collected help to understand why N-cyclohexyl monoamides are generally more efficient than their N-phenyl analogues as liquid-liquid extractants for iron(III) from 3 to 5 M hydrochloric acid solutions, and clearly denote that N-phenyl monoamides are essentially monomeric whereas N-cyclohexyl monoamide derivatives have a tendency to aggregate in the organic solution.     

N,N-二异丙基乙二胺的合成工艺改进

以丙烯酰胺和二异丙胺为原料,创新性地采用三氟甲磺酸脯氨酸盐为催化剂,经过Michael加成反应合成N,N-二异丙氨基丙酰胺;再经过Hofmann降解反应得到N,N-二异丙基乙二胺,总收率54.0%,产品结构经过1H NMR、MS表征确证。     

Study on micellization of poly(N‐isopropylacrylamide‐butyl acrylate) macromonomers in aqueous solution

A kind of thermo‐sensitive macromonomer, styrene‐terminated poly(N‐isopropylacrylamide‐butyl acrylate) [P(NIPAm‐BA)] has been synthesized in this work. With the help of ultraviolet spectrum (UV), proton nuclear magnetic resonance (¹H‐NMR), potentiometric titration and dynamic light scattering (DLS), the molecular structure, thermo‐sensitive characteristics, and micellization behaviors of this kind of macromonomer have been investigated. The obtained results demonstrate that, the molecular structure of thermo‐sensitive macromonomer, including the content of comonomer unit on the backbones and the variety of terminal groups, has great influence on its low critical solution temperature (LCST) and critical micelle concentration (CMC). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A new fundamental solution for differential Riccati equations arising in control

The matrix differential Riccati equation (DRE) is ubiquitous in control and systems theory. The presence of the quadratic term implies that a simple linear-systems fundamental solution does not exist. Of course it is well-known that the Bernoulli substitution may be applied to obtain a linear system of doubled size. Here, however, tools from max-plus analysis and semiconvex duality are brought to bear on the DRE. We consider the DRE as a finite-dimensional solution to a deterministic linear/quadratic control problem. Taking the semiconvex dual of the associated semigroup, one obtains the solution operator as a max-plus integral operator with quadratic kernel. The kernel is equivalently represented as a matrix. Using the semigroup property of the dual operator, one obtains a matrix operation whereby the kernel matrix propagates as a semigroup. The propagation forward is through some simple matrix operations. This time-indexed family of matrices forms a new fundamental solution for the DRE. Solution for any initial condition is obtained by a few matrix operations on the fundamental solution and the initial condition. In analogy with standard-algebra linear systems, the fundamental solution can be viewed as an exponential form over a certain idempotent semiring. This fundamental solution has a particularly nice control interpretation, and might lead to improved DRE solution speeds.     

Potential recoverable natural gas resources in China

Carbon nanosheet films were deposited on Al substrates by using plasma assisted chemical vapor deposition (PACVD) technique. And after being peeled off from Al substrates, carbon nanosheet powders (CNSPs) were obtained. In Raman spectrum of carbon film, there was a strong and broadened peak at about 1,580 cm-1, indicating a carbon diamond-like film. Atomic force microscope image showed that the carbon diamond-like film had a grain size less than 100 nm, and its surface roughness Ra was 17.95 nm in an area of 5×5 μm2. The CNSPs were irregular sheets with curly edges and a length of several micrometers to several hundreds of micrometers. The BET surface area of CNSPs was 6.66 m2/g with no micro-pore present, which was confirmed by N2 adsorption-desorption characterization. In the adsorption testing, when the relative pressure P/P0 was higher than 0.3, the adsorption behavior did not follow the Langmuir equation. The addition of CNSPs to carbon black (catalyst support) could improve hydrodesuifurization performance of carbon supported Ni-W catalysts for diesel oil.     

Co‐composting an animal fatty‐proteinaceous waste with a solid lignocellulosic by‐product from the olive oil industry (‘alperujo’)

BACKGROUND: The production of biodegradable wastes and their disposal cause a major financial problem in many industrial activities. Co‐composting was thought to be a feasible alternative for disposing of a strongly alkaline waste from the pharmaceutical industry (AW), mainly consisting of animal fats and partially hydrolysed proteins in a stable emulsion. The AW was added gradually, during the early phase of the composting process, to a substrate made up of ‘alperujo’ (AL), the wet, lignocellulosic, solid by‐product of the olive oil industry, and fresh horse manure, which was added to improve the physical structure of the composting substrate. RESULTS: The addition of AW reduced organic matter degradation during composting, enriched the amount of organic compounds in the water‐ and alkali‐soluble fractions and increased mineral salt contents. Thus, significantly higher electrical conductivity, humification indices and contents of organic matter, P, K and Na were recorded in the end‐composts resulting from AW treatments. However, the application of one AW‐based compost led to soil N immobilisation, as revealed by an incubation experiment, which must be considered in order to avoid potential N starvation in the short term. CONCLUSION: According to these results, composting can be used as a disposal alternative for AW, leading to end‐products with potential uses as organic amendments or fertilisers for agricultural systems. In addition, these composts could be used to produce alternative liquid organic fertilisers, based on the extraction of their humic‐like fraction. Copyright © 2009 Society of Chemical Industry     

Robust Multigrid Methods for Nearly Incompressible Elasticity

We consider multigrid methods for problems in linear elasticity which are robust with respect to the Poisson ratio. Therefore, we consider mixed approximations involving the displacement vector and the pressure, where the pressure is approximated by discontinuous functions. Then, the pressure can be eliminated by static condensation. The method is based on a saddle point smoother which was introduced for the Stokes problem and which is transferred to the elasticity system. The performance and the robustness of the multigrid method are demonstrated on several examples with different discretizations in 2D and 3D. Furthermore, we compare the multigrid method for the saddle point formulation and for the condensed positive definite system. Received February 5, 1999; revised October 5, 1999