主动授权规则实施支持空间特性的RBAC*

为满足安全策略或者角色定义的变化,系统或模型应该提供一种灵活的机制实施支持空间特性的RBAC。引入了OITE（on-if-then-else）主动授权规则实施支持空间特性的RBAC,定义了支持空间特性的RBAC中各基本元素与OITE之间的映射关系。使用OITE作为实施机制,可以在不同粒度上实施带有空间特性角色约束,并且可以将支持空间特性的RBAC应用在多个领域中。最后简要讨论了授权规则如何从支持空间特性的RBAC安全策略中自动产生。     

Characteristics of oxygen consumption of coal at programmed temperatures

Oxygen consumption is an important index of coal oxidation.In order to explore the coal-oxygen reaction,we developed an experimental system of coal spontaneous combustion and tested oxygen consumption of differently ranked coals at programmed temperatures.The size of coal samples ranged from 0.18~0.42 mm and the system heat-rate was 0.8℃/min.The results show that,for high ranked coals,oxygen consumption rises with coal temperature as a piecewise non-linear process.The critical coal temperature is about 50%.Below this temperature,oxygen consumption decreases with rising coal temperatures and reached a minimum at 50℃,approximately.Subsequently,it begins to increase and the rate of growth clearly increased with temperature.For low ranked coals,this characteristic is inconspicuous or even non-existent.The difference in oxygen consumption at the same temperatures varies for differently ranked coals.The results show the difference in oxygen consumption of the coals tested in our study reached 78.6% at 100 ℃.Based on the theory of coal-oxygen reaction,these phenomena were analyzed from the point of view of physical and chemical characteristics,as well as the appearance of the coal-oxygen complex.From theoretical analyses and our experiments,we conclude that the oxygen consumption at programmed temperatures reflects the oxidation ability of coals perfectly.     

Decarburization rate of RH refining for ultra low carbon steel

The decarburization behaviors of ultra low carbon steel in a 210-t RH vacuum degasser were investigated under practical operating conditions.According to the apparent decarburization rate constant (KC) calculated by the carbon content in the samples taken from the hot melt in a ladle at an interval of 1-2 min,it is observed that the total decarburization reaction period in RH can be divided into the quick decarburization period and the stagnant decarburization period,which is quite different from the tradit...     

Additive-aided electrochemical deposition of bismuth telluride in a basic electrolyte

A new basic electrolyte with two cationic plating additives,polydiaminourea and polyaminosulfone,was investigated for the electrochemical deposition of the bismuth telluride film on a nickel-plated copper foil.Tellurium starts to deposit at a higher potential(-0.35 V) than bismuth(-0.5 V) in this electrolyte.The tellurium-to-bismuth ratio increases while the deposition potential declines from-1 to-1.25 V, indicating a kinetically quicker bismuth deposition at higher potentials.The as-deposited film featu...     

高等教育与农村经济发展关联分析

本文从高等教育的角度入手,采用关联分析的方法研究了高等教育对农村经济发展的作用。并根据研究结果得出了一些关于发展高等教育和农村经济的建议。     

非典型SVOC结构构式义分析

根据构式语法,典型SVOC结构（即NP2后是名词短语和形容词短语）的构式义是致使变化。而SVOC结构研究中争议较大之处是如何看待和界定NP2后是非限定结构的情况。根据语义分析,这类情况中有些是属于非典型SVOC结构,其意义仍然是致使变化,而另外一些则应视为其它句式,如SVO。不同的学者从不同的角度出发往往得出不同的结论,这种情况从原型范畴理论的角度来看是完全可以理解并且是非常正常的。     

基于PDCA循环工作法实施科学化管装

针对当前我军科学化管装的现状,本文从提高科学化管装的水平入手,综合运用PDCA循环工作法的相关原理,结合当前的实际,就如何提高科学化管装水平进行了探索性的思考,并提出了相关的改进措施。     

Synthesis and characterization of soluble aromatic azopolyamides containing sulfone and ether units

A series of new polyamides 3a–d containing aryl-azo, ether and sulfone groups in the main chain were synthesized from bis[4-(4-aminophenoxy)phenyl sulfone] 1 and several azo aromatic diacyl chlorides 2a–d by the low temperature solution polycondensation technique. FTIR spectroscopy, nuclear magnetic resonance (NMR) and elemental analyses confirmed the structure of these polymers. Owing to the aryl and amide groups in the main chain, these polymers exhibit photochromic properties as well as excellent thermal stabilities. The transition temperatures (T _g) are between 242 and 265 °C, and the char yields at 800 °C in nitrogen atmosphere were above 39%. Based on incorporation of flexible ether linkages and polar sulfone groups, the polyamides show desirable solubility in organic solvents such as DMAc, N,N-dimethylformamide (DMF), N-methyl-2-pyrroidinone (NMP) and dimethylsulfoxide (DMSO). And it is exemplified that polyamide containing 2 and 2′ substitutes performed better solubility. Funded by the National Natural Science Foundation of China (No. 50572081)     

Evolution of carbides and carbon content in matrix of an ultra-high carbon sintered steel during heat treatment process

DTA, thermal expansion, XRD, and SEM were used to evaluate the effect of quenching temperature on the mechanical properties and microstructure of a novel sintered steel Fe-6Co-1Ni-5Cr-5Mo-1C. Lattice parameters and the mass fraction of carbon dissolved in the matrix of the steel quenched were investigated. It is discovered that the hardness of the steel increases with quench-ing temperature in the range of 840-900℃ and remains constant in the range of 900 to 1100℃. It decreases rapidly when the tem-perature is higher than 1100℃. The mass fraction of carbon dissolved in the matrix of the steel quenched at 840℃ is 0.38, but when the quenching temperature is increased to 1150℃, it increases to 0.98. The carbides formed during sintering are still present at grain boundaries and in the matrix of the steel quenched at low quenching temperatures, such as 840℃. When the quenching temperature is increased to 1150℃, most of the carbides at grain boundaries are dissolved with just a small amount of spherical M23C6 existing in the matrix of the quenched steel.     

Failure mode and strength anisotropic characteristic of stratified rock mass under uniaxial compressive situation

A stratified rock mass model was founded by FLAC^3D. The failure mode and anisotropic characteristic of strength for stratified rock mass were analyzed. The analysis results show that the numerical simulation can visually reflect the failure modes of rock samples under different inclination angles β of structural plane. The stiffness of rock sample before peak strength changes in the compressive procedure. With the increase of β, the compressive strength σ _c of rock sample decreases firstly and then increases; when β is in the range of 20°–30° and 80°–90°, σ _c has the largest sensitivity to β; while β falls in the range of 30°–70°, σ _c varies little. When ϕ _j <β<90° (β _j is friction angle of structure plane), the results obtained from numerical simulation and theoretical analysis are in almost the same values; while β⩽ ϕ _j or β=90°, they are in great different values. The results obtained from theoretical analysis are obvious larger than those from numerical simulation; and the results from numerical simulation can reflect the difference of compressive strength of rock samples for the two situations of β⩾ ϕ _j and β=90°, which is in more accordance with the real situation. Foundation item: Project (50099620) supported by the National Natural Science Foundation of China