水工混凝土空蚀过程中的热学作用研究

随着坝工技术水平的提高和水力资源的深入开发利用,高坝建设发展迅速,其泄量大、流速高时的泄洪消能和防冲保护问题是目前建设中主要技术难题。传统设计以力学破坏机理为基础,采用高强混凝土未从根本上解决水工抗空蚀问题。通过电火花空泡发生装置的研制结合高速摄像机观察了空泡的发生及溃灭过程,并利用超声波空化设备进行了水泥净浆空蚀试验,探讨了热学作用在混凝土空蚀破坏中可能性,尝试从另一角度研究高速水流下水工混凝土的空蚀作用机理,剖析目前水工混凝土建筑物空蚀破坏中力学作用和热学作用关系,为高速水流下水工混凝土材料的防空蚀技术提供对策依据。

DIS Lab在中学热学教学中的应用

随着科学技术的发展进步,信息技术和与教育改革相结合,以技术为辅助的教育方式成为新世纪教育发展的方向。在这样的教育改革形势下,中学热学教学作为中学物理课程的难点必须应用现代高科技的实验器材和试验手段进行教学,使中学热学教学内容通俗易懂和深入浅出。本文对DIS实验进行了全面介绍,并对DIS实验在中学热学教学中的作用和优劣势进行了分析。

Comparison of mechanical properties in high temperature and thermal treatment granite

Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious form, stress-strain curve, peak strength, peak strain and elastic modulus with temperature were analyzed and the essence of rock failure modes was explored. The results indicate that, compared with granite after the high temperature treatment, the brittle-ductile transition critical temperature is lower, the densification stage is longer, the elastic modulus is smaller and the damage is larger under high temperature. In addition, the peak stress is lower and the peak strain is greater, but both of them change more obviously with the increase of temperature compared with that of granite after the high temperature treatment. Furthermore, the failure modes of granite after the high temperature treatment and under high temperature show a remarkable difference. Below 100 ℃, the failure modes of granite under both conditions are the same, presenting splitting failure. However, after 100 ℃, the failure modes of granite after the high temperature treatment and under high temperature present splitting failure and shear failure, respectively.

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in aqueous solutions and its applications in binary and ternary aqueous solutions

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.

Thermodynamic Analysis of Desulfurization of Fine Coal by Electrochemical Reduction Flotation

Problems in desulfurization of coal by electrochemical reduction is analyzed and calculated. The result shows that 1 ) the △rGm function of the reaction of pyrite into FeS and the modifying reaction decreasing the oxygenous functions on coal surface is smaller than zero in a spontaneous reaction, and greater than zero in a non-spontaneous reaction; 2) the △rGm value can be adjusted by pH and the dosage of electrolyte to make it be greaterthan zero , which is favorable for the modifying reaction and useful for desulfurization of coal. The research has provided a theoretical foundation for determining reasonable technical parameters of desulfurization。

Hydrothermal synthesis and characterization of two novel inorganic-organic hybrid materials

By using different organic ligands, two 3D inorganic-organic hybrid compounds Co（C4H4N2）（VO3）2 1 and Co（C12H12N2）（VO3）2 2 were synthesized by hydrothermal reaction and characterized by X-ray crystallography. Crystal data： 1. crystal system orthorhombic, space group Pnna, a=1 0.188（2） A, b=1 1.497（2） A, c=7.3975（15） A, V=866.5（3） A^3, Z=4, Dcalcd= 2.705 g/cm^3; 2. crystal system triclinic, space group P1^- （No. 2）, a=8.3190（17） A, b=8.4764（17） A, c=1 1.183（2） A, a=95.48（3）°, β=92.03（3）°, γ=107.24（3）°,V=748.0（3） A^3, Z=2, Dcalcd= 1.958 g/cm^3. The framework of compound 1 contains both {Co（C4H4N2）} and infinite metavanadate chains. Crystal structure of compound 2 is constructed with inorganic {CoV2O6} layers across-linked by organic 1,2-bis（4-pyridyl） ethane ligands. The two compounds are thermally stable to approximately 410 ℃ and 350 ℃, respectively. Their optical band gaps are determined to be 2.13 eV and 2.12 eV by UV-VIS-NIR diffuse reflectance spectra, which revealed their nature of semiconductor and optical absorption features.

Thermodynamic behaviors of Cu in interaction with chlorine, sulfur, phosphorus and minerals during sewage sludge co-incineration

Thermodynamic equilibrium calculations were performed to reveal effects of interactions among Cl, S, P and other minerals on Cu migration. Our results showed that HCl（g）, SO2（g） and （P2O5）2（g） were released from the sewage sludge co-incineration. Cl was found to weaken adsorption of Cu by Al2O3, CaO and Fe2O3, while S de- layed reactions of Fe2O3 and Al2O3 with Cu, with P having no effect on reactions between the minerals and Cu. Among the coupled systems ofCl, S and P, the co-existences of Cl and S, and Cl, S and P were determined to inhibit Cu volatilization, and the co-existence of Cl and P had an enhancing effect Cu migration was affected only by S in the S and P system. With the SiO2, CaO and Al2O3 system, both Cl alone and Cl and P led to failed reactions be- tween the minerals and Cu. In the systems of S, S and Cl, S and P, and S, Cl and P, the migration behavior of Cu was mainly affected by S at low temperatures and by Cl at high temperatures, whereas P had no effect on Cu mi- gration during the entire nrocess.

Salt Effect on the Liquid-Liquid Equilibrium of （Water ＋ Propionic Acid ＋ Cyclohexanol） System at T=（298.2,303.2,and 308.2） K

Effects of salt and temperature on the liquid phase equilibrium of the(water + propionic acid + cyclohexanol) system were investigated.The liquid-liquid equilibrium data in the presence of KCl for various salt ionic strength of 0.5,1.0,1.5,2.0,and 2.5 mol·dm3 and in absence of the salt at T=(298.2,303.2,and 308.2)K were determined.The experimental results were correlated based on the Othmer-Tobias equation and Pitzer ion-interaction model.Thermodynamic properties such as distribution coefficients and activity coefficients of propionic acid in water + cyclohexanol were determined.In addition,the separation factor,S,of the chosen solvent was obtained for the investigated system.

Determination of thermodynamic properties in full composition range of Ti-Al binary melts based on atom and molecule coexistence theory

The results of predicting thermodynamic properties in the full composition range of Ti-Al binary melts in a temperature range from 1973 to 2273 K were obtained by coupling with the developed thermodynamic model for calculating mass action concentration N_i of structural units in Ti-Al system based on the atom and molecule coexistence theory（AMCT）. Temperature dependence of the activity coefficients of Ti and Al in natural logarithmic form in the infinitely dilute solution（0x_（Ti）0.01） of Ti-Al binary melts was also determined from the calculated activity coefficients of Ti and Al at temperatures of 1973, 2073, 2173, and 2273 K. The standard molar Gibbs free energy change of dissolving pure liquid element i（l） for forming 1%（mass fraction） element i in Ti-Al binary melts further was deduced. With the aid of this model, meanwhile, the determined excess thermodynamic properties, such as the excess molar mixing Gibbs free energy/entropy/enthalpy were also calculated.

Advance in Research on Biological Function and TranscriptionalControl of Heat Shock Proteins

The regulation of heat shock transcription factor to heat shock protein expression and the newest knowledge about the effect of heat shock protein on aging,immune response and the balance of cell survival and apoptosis are summarized in the paper.

Study on the Irreversible Thermodynamics of a Marine Engine Exhaust-powered Adsorption Refrigerating System

This study investigates the heat and mass transfer mechanism of a marine engifie exhaust-powered adsorption refrigerating system by using irreversible thermodynamics. The equations of entropy-production rate and the linear phenomenological equations of thermodynamic flux and force are established. The conventional experimental facilities of unit tube are developed and the phenomenological coefficients are obtained by fitting the experimental data. It is concluded that the thermodynamic process in the adsorbent bed is determined by the coupling effect of the heat and mass transfer; furthermore, the mass transfer is determined by the heat transfer. Taking some measures to increase heat transfer can improve the performance of the adsorption refrigerating system. The conclusions presented in this paper may be of value to the engineering applications of the system.

ADSORPTION OF MACROPOROUS PHOSPHONIC ACID RESIN FOR INDIUM

The adsorption kinetics and mechanism of a novel chelate resin, macroporous phosphonic acid resin (PAR) for In(III) were investigated. The statically saturated adsorption capacity is 216mg穏-1resin at 298K in HAc-NaAc medium. The apparent adsorption rate constant is k298=4.84?0-5 s-1. The adsorption behavior of PAR for In(III) obeys the Freundlich isotherm. The thermodynamic adsorption parameters, enthalpy change △H, free energy change △G and entropy change △S of PAR for In(III) are 11.5kJ/mol, -12.6kJ/mol and 80.8J/mol稫, respectively. The apparent activation energy is Ea=3.5kJ/mol. The molar coordination ratio of the functional group of PAR to In(III) is about 3∶1.

Impacts of Choerospondias axillaris Growth on Acidity of Udic Ferrosols in Subtropical China

Changes in acidity of Udic Ferrosols, caused by growth of Choerospondias axillaris (Roxb.) Burtt et Hill, in comparison to wild grass, were investigated for pH distribution in the soil profile, exchangeable acidity, and cation status in the soil leachate of a simulated leaching experiment. Soils were sampled in profiles at 5 cm intervals to a depth of 100 cm. In the 15-60 cm layer the soils with 10-year old C. axillaris had significantly lower pH (P < 0.05), with the largest difference being 0.41; and in…

THERMODYNAMICS ADSORPTION OF MANGANESE ION ON 1-(2-PYRIDYLAZO)-2-NAPHTHOL-6-SULPHONIC ACID IMPREGNATED RESIN

An ion-exchange resin of type 201×7 was impregnated with the reagent 1-(2-Pyridylazo)-2-naphthol-6-sulphonic Acid (PAN-S). The adsorption characteristics of PAN-S resin for manganese ion were studied on the static equilibrium adsorption. Within temperature range of 288K^313K and the concentration range investigated, equilibrium data for the adsorption of manganese ions from aqueous solutions by PAN-S resin were obtained and correlated with Freundlich and Langmuir equation. The results showed that the process of the adsorption of manganese ions from aqueous solution by PAN-S was an exothermic process. Estimations of the isothermic enthalpy change of adsorption,free energy change and entropy of adsorption are reported,and the adsorption behaviors are reasonably interpreted.

Ruppeiner Geometry of (2+l)-Dimensional Spinning Dilaton Black Hole

In this paper, we study the geometrothermodynamics of （2 ＋ 1）-dimensional spinning dilaton black hole. We show that the Ruppeiner curvature vanishes, which implies that there exist no phase transitions and thermodynamic interactions. However when the thermodynamics fluctuation is included, the geometry structure is reconsidered. The non-vanishing Ruppeiner curvature is obtained, which means the phase space is non-flat. We also study the phase transitions and show that it can indeed take D/ace at some points.

Molecular modeling study of the effect of base methylation on internal interactions and motions in DNA and implication to B-Z conformation change

Methylation in the bases of DNA is known to induce B-Z conformation change. In this work, molecular mechanics and normal mode analysis are used to probe how certain methylation affects the internal interactions and thermodynamic motions in the DNA double helixes in both B and Z conformations, and its implication to B-Z conformation change. By molecular modeling with Insight II, two cases involving cytosine C5 and guanine C8 methylation on both B and Z-form DNA duplex d(CGCGCG)2 are studied in comparison with the corresponding unmethylated duplexes. The internal interaction energies computed based on a molecular mechanics force field and the entropies due to internal motions computed according to a normal mode analysis are in fare agreement with respective observed thermodynamic quantities. The analysis on the computed individual energy terms suggests that the observed B-Z conformation change induced by methylation is primarily driven by enthalpic factors. A combination of changes in Van der Waals interaction, electrostatic interaction and hydrogen bonding likely contributes to the change of enthalpy that favors Z-conformation in the methylated states.

Determination of a Pore Structure Parameter of Porous Media by Analysis of Percolation Network Model

According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the 'chamber-throat' model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.

Microscopic Theory of Nonlinear Spin Waves in Ferromagnets

Considering the attractive interaction between ferromagnet, we propose the model of magnon-pairs, which two magnons with opposite wave vectors in a Heisenberg is suitable for low-temperature environment. A dressed magnon is an energy quantum of the magnon-pairs whose energy is a monotonically increasing function of absolute temperature. Based on the model, we re-investigate the excitation mechanism and thermodynamic properties of the Heisenberg ferromagnet. The correction factor e（O） plays an important role in studying the low-temperature properties of a ferromagnet.

Rheological characterization of A201 aluminum alloy

The thermodynamic characterization as well as the rheological characterization of the A201 alloy were conducted.Thermodynamic simulations (CALPHAD method) and calorimetric experiments were performed to determine the solidus and liquidus temperatures, the melting range and the sensitivity of the solid fraction at the thixoforming temperatures.The rheology of aluminium alloy A201 was examined using a high temperature Searle rheometer.The flow behaviour was analyzed with concentric cylinders of graphite to avoid chemical interactions with the liquid or semi-solid aluminium.The rotational body was grooved to prevent a phenomenon called wall slippage.Continuous cooling experiment was used to observe the shear rate effects on the flow behaviour.It can be seen that the viscosity level decreases at higher shear rates.Shear rate jump experiment was carried out to evaluate the steady state flow curve within the analyzed shear rate range from 60 s-1 to 260 s-1.It is found that the power law indexes are-1.35 and-1.49 for 35% and 45% solid fraction, respectively.Finally, some mechanical property data of as-cast and as-thixoformed A201 alloy are included indicating the potential for high strength applications.

Inclusion behavior of oxybutynin with hydroxypropyl-β-cyclodextrin

Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of the inclusion behavior. Thermodynamic constants AG, AH and AS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1：1 is formed, and inclusion stability constant between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding ability with HP-β-CD in aqueous solution （stability constant 〈102 L/mol） and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes to the inclusion process. AG, AH and AS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process.