水盐体系组分数计算公式的一个条件

给出了水盐体系组分数计算公式（ｃ＝ｍ＋ｎ）的一个证明。

Explosion limits for combustible gases

Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit （LEL） and Upper Explosion-Limit （UEL） of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of HE increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.

Research on Co-seismic Displacement of the Yutian MS7.3 Earthquake Based on the High Frequency Data of GNSS

After the Yutian M_S7.3 earthquake,the authors instantly collected 1Hz high frequency data of the 4 reference stations within 350 km around the epicenter,and calculated the GNSS data with the TRACK module. The results showed that:( 1) The co-seismic displacement of Yutian station,about 54 km from the epicenter,is the most obvious,particularly in the EW component,with a change of about 52.5 ± 11mm,which is more than three times the mean-square error of calculating precision.( 2) In the Yutian reference station,the biggest variation in the EW component appeared within 1 minute after the earthquake.( 3) The change in the NS component is not great.

Generation of Flat Supercontinuum in a Single-mode Optical Fiber with a Convex Chromatic Dispersion Profile

A single-mode optical fiber with a convex chromatic dispersion profile is proposed for generating a flat supercontinuum(SC).The fiber has normal dispersion and the dispersion parameter D(λ,z) is a convex function of wavelengths.It is shown from the numerical results that the chromatic dispersion,the flatness of the dispersion curve and the pump conditions have significant effect on SC generation.A flat and broad SC without strong residual pump component can be obtained when the pump wavelength is set in the vicinity of the wavelength at which the fiber has small normal group-velocity dispersion(GVD) and small dispersion slope.The fiber with a smaller normal GVD,a flatter dispersion profile and a higher nonlinear coefficient are more suitable for broad SC generation.

On the Crossing Numbers of K5 × Sn

By connecting the 5 vertices of K5 to other n vertices, we obtain a special family of graph denoted by Hn. This paper proves that the crossing number of Hn is Z（5, n） ＋2n＋ [n/2] ＋1, and the crossing number of Cartesian products of K5 with star Sn is Z（5, n） ＋ 5n ＋ [n/2] ＋ 1.

The Existence of Solutions of Initial Value Problems for Nonlinear Second Order Impulsive Integro-Differential Equations of Mixed Type in Banach Spaces

By the use of MSnch fixed point theorem and a new comparison result, the solutions of initial value problems for nonlinear second order impulsive integro-differential equations of mixed type in Banach spaces are investigated and the existence theorem is obtained.

Determination of T-stress using finite element analysis

A method that uses finite element analysis to determine the non-singular stress （T-stress） at a crack tip is proposed in this study. T-stress includes two components： the Tx-stress parallel to the tangent of the crack at its tip and the Ty-stress perpendicular to this tangent. The effects of contact and friction on both the Tx- and Ty-stresses on the crack flanks are considered in the method. Because the method uses a single standard elastic finite element analysis derived directly from the equation of the stress fields around the crack tip and does not require any assumptions or simplification, it can be used to determine the T-stress for any given geometry and loading condition. Theoretical results are used to calibrate the results, which exhibited good agreement and to discuss the T-stress computational methodology. Furthermore, the Tx- and Ty-stresses in center-cracked Brazilian disc （CCBD） specimens subjected to diametrical or partially distributed compression were numerically computed, and the effects of contact and friction on the Tx- and Ty-stresses are discussed.

A New Black Box Analysis of Hash Functions Based on Block Ciphers

For the 64 most basic ways to construct a hash function H:{0,1} → {0,1}n from a block cipher E:{0,1}n × {0,1}n → {0,1}n, Black et al.provided a formal and quantitative treatment of the 64 constructions, and proved that 20 schemes are collision resistant.This paper improves the upper and lower bounds and make contrast with a hash constructed from a random oracle.These 20 schemes have only one kind of collision resistance upper and lower bounds.In addition, we present new advantages for finding second preimages.

Molecule-based modeling of heavy oil

A molecular-level kinetics model has been developed for the pyrolysis of heavy residual oil. Resid structure was modeled in terms of three attribute groups: cores, inter-core linkages, and side chains. The concentrations of attributes were constrained by probability density functions (PDFs) that were optimized by minimizing the difference between the properties of the computational representation-which were obtained by juxtaposing the attributes-to measured properties, which were obtained by analytical chemistry measurements. Computational tools were used to build a reaction network that was constructed based upon model compounds and their associated kinetics. For cases with an intractable number of species, equations were written in terms of the three attribute groups and the molecular composition was retained implicitly through the juxtaposition. These modeling methods were applied to the Shengli and Daqing resids. The composition of the simulated molecular feedstock fit well with analytical chemistry measurements. After simulated pyrolysis, both resids showed representative increases in the weight fractions of lighter hydrocarbons. Relevant end-use properties were predicted for the product mixtures.