Short—range structural change in indium melt by Gaussian peaks decomposing of RDF

Liquid indium‘s structure was studied at 280,390,550,650,and 750℃ respectively by suing an elevated temperature Xray diffractometer,and its radial distribution function(RDF)at different temperatures was decomposed into 4 Gaussian peaks in the range of 0.2-0.6nm.postitons of the decomposed Gaussian peaks were compared with the nearest and the second nearest neighbor atomic distances,respectively.It is shown that the position of the first decomposed gaussian peak is similar to the nearest neighbor atomic distance in liquid In at the corresponding temperature,and that of the thuird decomposed Gaussian peak is similar to the second nearest neighbor atomic distance.Morevoer,the first and the third Gaussian peaks correspond to the first and the second atom shells of liqud In at the corresponding temperatures,respectively.Therefore,the position and the area of Gaussian peaks can represent the postion and atom number of corresponding shells,Based on this result.short-range structural change in liquid In was studied.It was found that the first and the second shells are close to the referred atom.and the atom number at the shells decreases with the inreasing temperature from 280 to 750℃.In different ranges of temperature,structural Changes in the first and the second shells show diferent features.     

A statistical approach to fit Gaussian part of full-energy peaks from Si(PIN) and SDD X-ray spectrometers

A new statistical fitting approach,named Statistical Distribution-Based Analytic(SDA)method,is proposed to fit single Gaussian-shaped Kαand KβX-ray peaks recorded by Si(PIN)and silicon drift detector(SDD).In this method,we use the discrete distribution theory to calculate standard deviation of energy resolutionσ.The calibration ofσand energy(E)for two detectors between the energy ranges of 4.5–26 keV are also completed by measuring characteristic X-ray spectra of nineteen types of pure elements.With the spectrum fraction(SF)parameter proposed in this paper,the SDA method can be used to resolve overlapping peaks.In measured spectra,the Gaussian part of X-ray peaks can be fitted by a Gaussian function with two parameters,σand SF.This new fitting approach is simpler than traditional methods and it achieves relatively good results when fitting the complex X-ray spectra of national standard alloy samples detected by Si(PIN)and SDD detectors.The2r values are obtained for each spectrum to assess fitting results,and the SDA fitting method gives a preferable fit for the SDD detector.     

A study on the bonding structure of CaO-SiO_2 slag by means of molecular dynamics simulation

The investigation results of the bonding structure of CaO-SiO_2 slag by means of molecular dynamics simulation are presented. The characteristics of partial radial distribution function g_(ij) (r) are in good agreement with the measurement of X-ray diffraction, and the variation of Q_n with different SiO_4 tefrahedra following the change of X_(CaO) is consistent with the results of Raman spectroscopy. The partial vibrational density of states F_(Si)(ω) shows that two bands appear in the range of 636-737 cm~(-1) and 800-1200 cm~(-1) respectively which are also consistent with Raman spectroscopy.     

Molecular Dynamics Simulation of Hydrate Decomposition Under Action of Alcohol Inhibitors

The molecular dynamics method is used to investigate decomposition of methane hydrate at different temperatures, pressures and concentrations of inhibitor. By analyzing the parameters of system conformation, mean square displacement and radial distribution function, the decomposition of hydrate in the presence of alcohol inhibitors ethylene glycol and glycerol is explored. The results show that the hydroxyl groups in alcohol molecules can destroy the cage structure of hydrate, and form hydrogen ...     

A theory of constructing locally supported radial wavelet frame and its application

A new method for constructing locally supported radial wavelet frame or basis, which is different from the multiresolution analysis, is proposed. A continuously differentiable radial function with a local support is chosen at first.Then a radial wavelet is obtained by the first and second derivatives of the radial function, If the radial function is both locally supported and infinitely differentiable, so is the radial wavelet. It is shown that the radial wavelet is a multidimensional dyadic one. I. Daubechies' wavelet frame Theorem is extended from one dimension to n dimensions. It is proven that the family generated by dilations and translations from a single radial wavelet can constitute a frame in L~2(R~n). Consequently, it is concluded that the radial wavelet family generated by dilations and translations combined with their linear combination can constitute an orthonormal basis in L~2(R~n). Finally, an example of the radial wavelet,which is inseparable and with a local support and infinitely high     

Blind source separation based on generalized gaussian model

Since in most blind source separation(BSS)algorithms the estimations of probability density function(pdf)of sources are fixed or can only switch between one sup-Gaussian and other sub-Gaussian model,they may not be efficient to separate sources with different distributions.So to solve the problem of pdf mismatch and the separation of hybrid mixture in BSS,the generalized Gaussian model(GGM)is introduced to model the pdf of the sources since it can provide a general structure of univariate distributions.Its great advantage is that only one parameter needs to be determined in modeling the pdf of different sources,so it is less complex than Gaussian mixture model.By using maximum likelihood(ML)approach,the convergence of the proposed algorithm is improved.The computer simulations show that it is more efficient and valid than conventional methods with fixed pdf estimation.     

Probabilistic analysis of geomembrane puncture from granular material under liquid pressure

A simplified probabilistic analysis of geomembrane punctures from granular material was presented when subjected to liquid pressure. The probability distribution of contact force between geomembrane and granular material was obtained based on the principle of equal probability and assumptions that grains are spheres with constant size. A particle flow code PFC^3D was employed to simulate the contact process which indicates a good agreement with the theoretical probabilistic analysis. The odds of geomembrane puncture from grains of constant size were obtained by evaluating the puncture force which should not exceed the puncture resistance of geomembrane. The effects of grain radius, grain rigidity and liquid pressure were studied in more detail and displayed in graphs. Both high-level of liquid pressure and large grain can result in high risk of geomembrane puncture. The influence of grain rigidity on the geomembrane puncture odds is significant. For granular material with a grain size distribution, the geomembrane puncture odds can be estimated by the grain size distribution, served as weight function and it is a cautious design if the largest grain is chosen as the design grain size.     

STUDY ON THE STRUCTURE OF IONIC CONDUCTOR FOR LiH-LiF-P_2O_5 GLASS SYSTEM

The system of LiH-LiF-P_2O_5 ionic conductorglass is prepared in neutral atmosphere and glass-forming region is given. The structure and coor-dination of glass are analyzed by IR spectra. Ramanspectra and RDF(r). The result indicates that the(PO_4), (PO_3F) and (LiF_4) tetrahedra are basicalstructure units of glass network and the coordina-tion number of Li is 4. The coordination number ofP is 4. The glass random network structure model isgiven. The study on structure shows that Li~+, H~- andpartial F~- are charge carriers in glass system.     

Equation of state of Zr41 Ti14 Cu12.5 Ni10 Be22.5 bulk metallic glass

The knowledge of the equation of state （EOS） and the compressibility of a solid are of central importance for the understanding of the behavior and the application of a condensed matter. The compression behavior of Zr41Ti14Cu12.5Ni10Be22. 5 bulk metallic glass （BMG） is investigated at room temperature up to 24 GPa using in-situ high pressure energy dispersive X-ray diffraction with synchrotron radiation. A model of basic cell volume has been established and the equation of state of BMG is determined by the calculation of radial distribution function. The experimental results indicate that the BMG contains a large amount of vacancy-like free volume. Low pressure （ below 7 GPa） induces the collapse of the free volume to some extent and structure relaxation in the BMG.     

Effect of Tire Repeated Root Modal on Tire Modelling with Experimental Modal

The effect of tire repeated root modal (RRM) on tire modeling with an experimental modal is studied. Firstly, a radial tire with radial and tangential RRMs is tested and analyzed. By multi-point exciting of the radial tire, a multiple reference frequency domain method based on a least squares (LMS PolyMAX) algorithm is used to identify modal parameters. Then, modal stability diagram (MSD), modal indication function (MIF) and modal assurance criteria (Auto-MAC) matrix are utilized to induce multiple inputs multiple outputs (MIMO) frequency response function (FRF) matrixes. The tests reveal that notable repeated roots exist in both radial and tangential response modes. Their modal frequencies and damping factors are approximately the same, the amplitudes of modal vectors are in the same order of magnitude, and the mode shapes are orthogonal. Based on the works mentioned, the method of trigonometric series modal shapes fitting is adopted, the effects of RRM model on tire modeling with a vertical experimental modal are discussed. The final results show that the effects of considering the RRM shapes are equivalent to the tire mode shapes depended on rotating the tire''s different exciting points during tire modeling, and since considering the RRM, the tire mode shapes can be unified and fixed during tire modeling.     

Advanced sludge reduction and phosphorous removal process

An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ（COD） is 332 - 420 mg/L, concentration of ammonia p（NH3-N） is 30 - 40 mg/L and concentration of total phosphorous p（TP） is 6.0 -9.0 mg/L in influent, the system still ensures ρ（COD）〈23 mg/L, ρ（NH3-N）〈3.2 mg/L and ρ（TP）〈0. 72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ（DO） is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91 %. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.     

Characteristics of pressure drop for single-phase and two-phase flow across sudden contraction in microtubes

Single-phase and gas-liquid two-phase pressure drops caused by a sudden contraction in microtubes were experimentally investigated at room temperature and atmospheric pressure, using nitrogen and water. The experimental results on pressure drop with a novel measurement method, the tiny gaps on the tubes, were used to characterize the sudden contraction pressure drop for tube diameters from 850 to 330 μm. The ranges of the gas and liquid superficial velocity were 2.55–322.08 and 0.98–9.78 m/s in the smaller tube respectively. In single-phase flow experiments, the contraction loss coefficients were larger than the experimental results from conventional tubes in the laminar flow. While in the turbulent flow, the contraction loss coefficients were slightly smaller than those from conventional tubes and predicted well by K _c=0.5×(1−σ²)^0.75. In two-phase flow experiments, the slip flow model with a velocity slip ratio S=(ρ_L/ρ_G)^1/3 showed a good prediction that reveals the occurrence of velocity slip. An empirical correlation for two-phase flow pressure drops caused by the sudden contraction was developed based on the proposed contraction loss coefficients correlation for single-phase flow and Martinelli factor. Supported by the National Key Basic Research Program (Grant No. G2000026300) and Beijing Open Fund     

Direct rapid determination of traces of sulfide in environment samples

An improved ethylene blue method for determination of sulfide is developed. It has been adapted to a direct determination of sulfide by both common spectrophotometric method and total differential spectrophotometric method. In common spectrophotometric method, the calibration curve is A=1.69ρ+0.006 and the correlation coefficient is 0.9994.The apparent molar absorptivity is 5.42×104 L*mol-1*cm-1 and calibration curve is liner when ρ is in the range of 0-0.9 mg*L-1. In total differential spectrophotometric method, the calibration curve is A=9.25ρ+0.004 and the correlation coefficient is 0.9996. The apparent molar absorptivity is 2.96×105 L*mol-1*cm-1and calibration curve is liner when ρ is in the range of 0-0.10 mg*L-1. The sensitivity of this method is increased significantly compared with the former ethylene blue method. The speed of reaction is also faster than the former one. The limit of detection is found to be 1.0 ng*mL-1 by both common spectrophotometric method and total differential spectrophotometric method. Ten replicate analyses of a sample solution containing 100 ng*mL-1sulfide give a relative standard deviation of 1.8%. The effects of various cations and anions on the determination of sulfide are studied and procedures for removal of interference is described. The method is used for the determination of sulfide in environment samples with satisfactory results.     

Asymptotic analysis of weakly nonlinear and forced oscillations

The restriction ofK-B averaging method is discussed and asymptotic solution of the weakly nonlinear and forced oscillationu″+ω ₀ ² u=εkcosωt−εu ³ is obtained by Struble technique. The conclusion about this oscillation derived with other method is discussed. The results show thatK-B method will break down whena andθ in the zeroth solution of above eqation are not slowly varying functions of timet. The stationary solution of weakly nonlinear oscillation,u″+ω ₀ ² u=εkcosω(ε)t-εu ³ is also analysed. Synopsis of the author Chen Feng, associated professor, born in October 1948, worked on experimental fracture mechanics in Sweden from 1990 to 1995 as a visiting scholar. Major research fields include perturbation and weight function method and its application, experimental mechanics. currently interested in rock fracture mechanics.     

Thermochemical Study of Mixed Ligand Complexes of Rare Earths with Glycine and L-alanine

In order to obtain the standard molar enthalpies of formation of Rare-Earth amino acid coordination compounds, precise isothermal solution-reaction calorimetric method was used. The value of Δ_rH _m ^Θ of two coordination reactions was determined at T=298.2 K. From the experimental results and other auxiliary values, the standard molar enthalpies of formation of Ln(Gly)_5/2(Ala)_3/2(ClO₄)₃·H₂O(s) [Ln=La, Yb] at T=298.2 K were obtained. The values of them is to be Δ_rH _m ^Θ [La(Gly)_5/2(Ala)_3/2(ClO₄)₃·H₂O(s)]=−3545.45 kJ/mol and Δ_rH _m ^Θ [Yb(Gly)_5/2(Ala)_3/2)(ClO₄)₃·H₂O(s)]=−3793.81 kJ/mol, respectively. QU Jing-nian: Born in 1954 Funded by the Teaching and Research Award Program for Outstanding Young Professors in High Education Institute, Ministry of Education, P. R. China     

A MIXED METHOD OF DETERMINING THETHERMAL STRESS FOR COLD ROLLER

Coldrollerisanimportantcomponentofthemill.Thecoldrolleroftherollingprocessisusedathightemperature,whichwouldcracktherollerandshortentheservicelifeoftheroller.UPtonow,ageneralcalculationmethodofthethermalstressofthecoldrolleristoincreasethesafetycoefficient.Thiscalculationmethodlackstheoreticalanalysis.Inordertosolvethisproblem,thispaperappliesforthefirsttimethenewlydevelopedfiniteanalyticalmethodandtheboundaryfittingcoordinatetransformationmethodtomillpracticeandprovidesaanalyticalbasisoftemp…     

Electrical Transport and Magnetic Properties of La0.67Ca0.33Mn1-xCrxO3 and La0.67＋xCa0.33-x Mn1-xCrxO3 （0.04≤x≤0.08）

A comparative study for two different series, La0.67Ca0.33Mn1-xCrxO3 and La0.67＋xCa0.33-x Mn1-xCrxO3 is performed with x changing from 0.04 to 0.08 through measurements of zero-field resistivity （p）, magnetoresistance （MR） and ac susceptibility （Z） as functions of temperature （T）. For the second group, a single insulator-metal transition was characterized by the resistivity maximum appears in p vs. T curve. For the first group, besides the resistivity peak appearing at higher temperatures, the sample shows evidence for the existence of another peak appearing at lower temperatures. Compared to the first group, the second group shows a significant enhancement in MR effect, while the measurement ofΧ-T dependence does not display obvious differences for the two series. Different behaviors observed in the two series are discussed by considering possible exchange interaction between Mn^3- ion and Cr^3- ion.     

A study on the bonding structure of CaO−SiO2 slag by means of molecular dynamics simulation

The investigation results of the bonding structure of CaO−SiO₂ slag by means of molecular dynamics simulation are presented. The characteristics of partial radial distribution functiong _ij(r) are in good agreement with the measurement of X-ray diffraction, and the variation ofQ _n with different SiO₄ tetrahedra following the change ofX _CaO is consistent with the results of Raman spectroscopy. The partial vibrational density of states Γ_Si(ω) shows that two bands appear in the range of 636–737 cm⁻¹ and 800–1200 cm⁻¹ respectively which are also consistent with Raman spectroscopy. Project supported by Shanghai Natural Science Foundation.     

Research on atomic states, physical properties and catalytic performance of Ru metal

Using the one-atom theory (OA) of pure metals, the atomic states of Ru metal with hcp structure, fcc structure, bcc structure and liquid state were determined as fol- lows: [Kr](4dn)3.78(4dc)2.22(5sc)1.77(5sf)0.23,Ψa(fcc-Ru)=[Kr](4dn)3.70(4dc)2.44 (5sc)1.42(5sf)0.44, Ψ a(bcc-Ru)=[Kr](4dn)4.00(4dc)2.22(5sc)1.56(5sf)0.22, Ψ a(L-Ru)=[Kr](4dn)4.00(4dc)2.00(5sc)1.52 (5sf)0.48. The potential curve and physical properties as a function of temperature for hcp-Ru such as lattice constant, cohesive energy, linear thermal expansion coeffi- cient, specific heat and Gibbs energy and so on were calculated quantitatively. The theoretical results are in excellent agreement with experimental value. The rela- tionship between the atomic states and catalytic performance was explained qualitatively and these supplied the designation of Ru metal and relative materials with theoretical instruction and complete data.