Monitoring damage evolution of steel strand using acoustic emission technique and rate process theory

Utilizing the acoustic emission(AE) technique, an experimental investigation into the damage evolution for steel strand under axial tension was described. The damage evolution model for steel stand relating the damage evolution to acoustic emission parameters was proposed by incorporating the AE rate process theory. The AE monitoring results indicate that damages occur in both elastic and plastic phases of steel strand. In elastic phase, AE signals are mainly sent out from the micro damage due to the surface friction among the wires of steel strand, while in plastic phase, AE signals emitted from the plastic deformation of wires. In addition, the AE cumulative parameters curves closely resemble the loading curve. The AE cumulative parameters curves can well describe the damage evolution process including the damage occurrence and damage development for steel strands. It is concluded that the AE technique is an effective and useful nondestructive technique for evaluating the damage characteristics of steel strand.

Effect of Rolling Process on Comprehensive Properties of Corrosion Resistant Steel for Bottom Plate of Cargo Oil Tanks

A new kind of corrosion resistant steelfor cargo oiltanks（COT）was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling process parameters were obtained through multi-pass thermalsimulation test.The finalrolling temperature is about 820 ℃,the finalcooling temperature is about 600 ℃,and the cooling rate should be controlled between 10 ℃/s and 20 ℃/s.Based on the above analysis of the results,three groups of rolling samples by thermo mechanicalcontrolprocess are prepared.The tensile strength,yield strength,and toughness of the corrosion resistant steelare measured,which meet the requirements of DH36 steel,it can instruct the actualrolling production.The corrosion behaviour is also researched by weight loss and electrochemicalimpedance spectroscopic method,and it is found that the steelhas good corrosion resistance performance,the best one is No.3 steel,the corrosion rate of which is about 1/4 of the accepted criterion.

Mathematical model and magnetic-control mechanism of the stability of rotating spray transfer

To realize stable rotating spray transfer in the region of high constant current is the key of realizing high deposition rate MAG welding process without helium in shielding gas and extending the welding current range of traditional MAG welding process. In this paper, the magnetic control mechanism of the rotating spray transfer is stated and mathematical model is given. Theoretic basis is established, which implements high deposition rate MAG welding process with magnetic control instead of helium in shielding gas.

Dynamic Behavior of Interest Rates in China

This paper intuitively examines the dynamic behavior of two highly relevant interest rates in China. The first one is the government rate, which is decided and published by the central bank and can be simulated by pure jump process. Estimation of the jump intension is given out. And by different robustness test, it keeps stable. The jump size has met the condition to make interest rate within reasonable bounds and shown some meaning of economic cycle behavior. The second one is the market rate, which is estimated by spline approximation based on the transaction data of government bonds. Several models, including Vasicek model, Vasicek-GARCH （1,1） model, CIR model, and CIR-GARCH（1,1）, are empirically tested and the best performance is done by the Vasicek-GARCH（1,1） model. Furthermore, the estimate bias problem due to the near unit root process is tested and evidenced by both traditional methods and GPH test. Impact of government rate on market rate is finally checked and analyzed.

Fine analysis on advanced detection of transient electromagnetic method

Fault fracture zones and water-bearing bodies in front of the driving head are the main disasters in mine laneways,thus it is important to perform their advanced detection and prediction in advance in order to provide reliable technical support for the excavation.Based on the electromagnetic induction theory,we analyzed the characteristics of primary and secondary fields with a positive and negative wave form of current,proposed the fine processing of the advanced detection with variation rate of apparent resistivity and introduced in detail the computational formulae and procedures.The result of physical simulation experiments illustrate that the tectonic interface of modules can be judged by first-order rate of apparent resistivity with a boundary error of 5%,and the position of water body determined by the fine analysis method agrees well with the result of borehole drilling.This shows that in terms of distinguishing structure and aqueous anomalies,the first-order rate of apparent resistivity is more sensitive than the secondorder rate of apparent resistivity.However,some remaining problems are suggested for future solutions.

Factors Affecting Chinese Raters' Rating of High-Stakes English Exam Essays

This study consists of two questionnaire surveys conducted in two stages to investigate factors that high-stakes exam essay raters believe to affect their rating behavior. Raters were all university Chinese teachers of English majors. Seventy-three participants in stage one and 75 in stage two responded to the same questionnaire. Both exploratory factor analysis and confirmatory factor analysis were used in data analysis. Results showed that there were generally six broad factors interfering with the rating process： rating scale, rater training, rating supervision, rater characteristics, eye-catching text features and rating condition. The interaction of those factors reflected the tension between the constraints executed by the test institution and raters＇ own knowledge and understanding of essay rating. This study may shed light on measures taken to improve essay rating quality.

Deposition rate of hafnium crystal bar by iodide process

Single variable and deposition weight methods were adopted in the experiment. The hafnium crystal bar was fabricated by the iodide process. Influence of hafnium filament temperature（K value）, temperature controlling method, types of feed, and the loading methods on the deposition rate were studied. The results show that the K value, temperature control method, types of feed, and the loading methods have obvious effects on the deposition rate of the hafnium crystal bar. The deposition rate increases with the K value rising in the range of certain temperature;the salt bath controlling temperature method could effectively obtain the better deposition rate; the greater the contact areas of the feeds are, the faster the deposition rate is.So, the optimal iodide deposition techniques of preparing hafnium crystal bar are as follows： hafnium turnings as feed,molybdenum feed retainer charging, salt bath temperature controlling under the higher K value.

Ergodicity of Reversible Reaction Diffusion Processes with General Reaction Rates

In this paper,a class of reaction diffusion processes with general reaction rates is studied.A necessary and sufficient condition for the reversibility of this calss of reaction diffusion processes is given,and then the ergodicity of these processes is proved.

Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas.Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB（hydroxyl-terminated polybutadiene） hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

Calculation of vibrational energy transition rates in acoustic relaxation processes for excitable gas molecules

To research the correlation between vibrational energy transition rates and acoustic relaxation processes in excitable gases, the vibrational relaxation theory provided by Tanczos [J. Chem. Phy3. 25, 439 （1956）] is applied to calculate the energy transition rates of Vibrational- Vibrational （V-V） and Vibrational-Translational （V-T） energy transfer in gas mixtures. The results of calculation for the multi-relaxation processes in various gas mixtures, consisting of carbon dioxide, methane, chlorine, nitrogen, and oxygen at room temperature, demonstrate that the acoustic energy stagnated in every vibrational mode is coupled with each other through V-V energy exchanges. The vibrational excitation energy will relax through the V-T de-excitation path of the lowest mode because of its fastest V-T transition rate, resulting in that only one absorption peak can be measured for most of excitable gas mixtures. Thus, an effective model is provided to analyze how the vibrational energy transition rates affect the characteristics of acoustic relaxation processes and acoustic propagation in excitable gas mixtures.

On Evaluating the Rate Function of Large Deviations for Jump Processes

This is a sequel to our joint paper in which upper bound estimates for large deviations for Markov chains are studied.The purpose of this paper is to characterize the rate function of large devia- tions for jump processes.In particular,an explicit expression of the rate function is given in the case of the process being symmetrizable.

Non-equilibrium thermodynamics analysis and its application in interfacial mass transfer

Interfacial transfer plays an important role in multi-phase chemical processes. However, it is difficult to describe the complex interfacial transport behavior by the traditional mass transfer model. In this paper, we describe an interfacial mass transfer model based on linear non-equilibrium thermodynamics for the analysis of the rate of interfacial transport. The interfacial transfer process rate J depends on the interface mass transfer coefficient K, interfacial area A and chemical potential gradient at the interface. Potassium compounds were selected as model systems. A model based on linear non-equilibrium thermo-dynamics was established in order to describe and predict the transport rate at the solid-solution interface. Together with accurate experimental kinetic data for potassium ions obtained using ion-selective electrodes, a general model which can be used to describe the dissolution rate was established and used to analyze ways of improving the process rate.