Influence of railway wheel tread damage on wheel-rail impact loads and the durability of wheelsets

Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation model.The relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is investigated.The calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are assessed.The results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.

Parallel Processing Based on Ship Maneuvering in Identification of Interaction Force Coefficients

The parallel processing based on the free running model test was adopted to predict the interaction force coefficients （flow straightening coefficient and wake fraction） of ship maneuvering. And the multipopulation genetic algorithm （MPGA） based on real coding that can contemporarily process the data of free running model and simulation of ship maneuvering was applied to solve the problem. Accordingly the optimal individual was obtained using the method of genetic algorithm. The parallel processing of multiopulation solved the prematurity in the identification for single population, meanwhile, the parallel processing of the data of ship maneuvering （turning motion and zigzag motion） is an attempt to solve the coefficient drift problem. In order to validate the method, the interaction force coefficients were verified by the procedure and these coefficients measured were compared with those ones identified. The maximum error is less than 5%, and the identification is an effective method.

SOLUBILITY OF Ca IN Mn AND INTERACTION COEFFICIENTS OF Al AND Fe ON Ca IN Mn AT 1350℃

Solubility of Ca in manganese and manganese alloys was measured under sealed conditions at 1350℃.The interaction coefficients of Al and Fe on Ca in Mn were evaluated with the exper- imental data.The standard free energy of liquid Ca in liquid Mn based on the 1 wt-% solu- tion standard was estimated as well.

SELF-INTERACTION COEFFICIENTS OF Ca AND Mg IN DILUTE Sn-BASED SOLUTION

The interaction coefficients of Ca.Ti and Mg in the dilute Sn-based solution have been de- termined at 1500℃.Experimental measurements were taken by equilibrating the slag-alloy systems with metallic Sn as flux and graphite as reducing agent under Ar atmosphere mixed with different portion of CO.It was found that a considerable error may produce if the coefficients of ε_(Ca)^(Ca),ε_(Mg)^(Mg)and ε_(Ti)^(Ti)in the molten Sn were neglected when the activities of the components CaO,MgO and TiO_2 in the slags were estimated by this method.

Comparison of Some Methods on Prediction of Activity Interaction Coefficient

Based on Miedema's semiempirical formation enthalpy model for binary alloys, free volume theory and ageneral solution model, a new model for prediction of activity interaction coefficient ε is proposed. The calculatedresults are better in agreement with the experimental values than the two previous models. The related theories andmodels are discussed according to the degree of agreement with experimental values.

Relation between stabilization energy, crystal field coefficient and the magnetic exchange interaction for Tb^(3+) ion

Based on a single ion model, Hamiltonian of the simplest form about magnetocrystalline anisotropy for Tb3+ ion was solved by using the numerical method. The relation between the stabilization energy, crystal field coefficient B20 and the magnetic exchange interaction was studied as temperature approaches to 0 K. The results show that the stabilization energy contributed by Tb3+ is linear with crystal field coefficient B20 approximately, but it is insensitive to the change of magnetic exchange interaction for the strong magnetic substances such as TbCo5, Tb2Co17 and Tb2Fe14B compounds.

Activity Interaction Coefficients of Si in Cu-Ti-Si Melts at 1550℃

Activitibs of Si in binary Cu-Si and ternary Cu-Ti-Si melts were measured at 1 550℃ by using a method of chemical equilIbrium between gas and liquid. The activity interaction coefficients of Si in the melts have been determined from the experimental data (lny = -5.69. s = 6.69. P2: = -26.22. E; =-43.96) and activity interaction coefficients of Ti in binary Cu-Ti melt at 1550℃ has been estimated from Sommer's data based on the regular solution model (lny =-1 .10. : = 2.95.p:=-2.10).

EFFECT OF TRACE ELEMENTS WITH ZERO SELF－INTERACTIONCOEFFICIENT ON CRYSTALLIZATION TEMPERATUREOF IRON CARBON ALLOYS

The effect of trace elements with zero self-interaction coefficient on crystallization temperature of iron carbon alloys was studied and the mathematic equation was developed based on thermodynamics in the present researeh. With the equation developed in this paper, the effects of nitrogen on crystallization temperature of Fe-3.45C-2.15Si0. 16Mn and Fe-3.45C-2. 15Si-0. 80Mn alloys were discussed.

Wave-current interaction with a vertical square cylinder at different Reynolds numbers

Large eddy simulation is performed to study three-dimensional wave-current interaction with a square cylinder at different Reynolds numbers, ranging from 1,000 to 600,000. The Keulegan-Carpenter number is relevantly a constant of 0.6 for all cases. The Strouhal number, the mean and the RMS values of the effective drag coefficient in the streamwise and transverse directions are computed for various Reynolds numbers, and the velocity of a rep- resentative point in the turbulent zone is simulated to find the turbulent feature. It is found that the wave-current interaction should be considered as three-dimensional flow when the Reynolds number is high; under wave-current effect, there exists a critical Reynolds number, and when the Reynolds number is smaller than the critical one, current effect on wave can be nearly neglected; conversely, with the Reynolds number increasing, wave-currentstructure interaction is sensitive to the Reynolds number.

Attenuation coefficients of gamma and X-rays passing through six materials

The aim of this study was to determine the attenuation of gamma and X-rays with different energies caused by passage through different materials.To this end,different materials with a range of atomic numbers were chosen to measure gamma and X-ray attenuation coefficients and to explore the mechanisms of interaction of gamma and X-rays with matter of various kinds.It is shown that the attenuation coefficients first decrease and then increase with increase in the radiation(photon)energy.The attenuation of gamma and X-rays passing through materials with high atomic number is greater than that in materials with low atomic number.The attenuation minimum is related to the atomic number of the irradiated materials.The larger the atomic number is,the lower the energy corresponding to attenuation minimum is.Photoelectric and Compton effects are the main processes when gamma rays pass through individual materials with high and low atomic numbers,respectively.Therefore,for radiotherapy and radiation protection,different methods should be considered and selected for the use of gamma and X-rays of different energies for use in different materials.

Examination of wind-wave interaction source term in WAVEWATCH Ⅲ with tropical cyclone wind forcing

Results of drag coefficient（CD） from field observations and laboratory wave tank experiments indicate that the operational wave model can overestimate wind energy input under high wind conditions. The wind-wave interaction source term in WAVEWATCH Ⅲ has been modified to examine its behavior with tropical cyclone wind forcing. Using high resolution wind input,numerical experiments under idealized wind field and tropical cyclone Bonnie（1998） were designed to evaluate performance of the modified models. Both experiments indicate that the modified models with reduced CD significantly decrease wind energy input into the wave model and then simulate lower significant wave height（SWH） than the original model. However,the effects on spatial distribution of SWH,mean wavelength,mean wave direction,and directional wave spectra are insignificant. Due to the reduced wind energy input,the idealized experiment shows that the modified models simulate lower SWH than the original model in all four quadrants. The decrease in the front quadrants is significantly larger than that in the rear quadrants;it is larger under higher winds than lower winds. The realistic experiment on tropical cyclone Bonnie shows that the modified model with the various downward trends of CD in high winds creates a simulation that agrees best with scanning radar altimeter observations.

Time-dependent Diffusion Coefficient and Conventional Diffusion Constant of Nanoparticles in Polymer Melts by Mode-coupling Theory

Time-dependent diffusion coefficient and conventional diffusion constant are calculated and analyzed to study diffusion of nanoparticles in polymer melts. A generalized Langevin equa- tion is adopted to describe the diffusion dynamics. Mode-coupling theory is employed to calculate the memory kernel of friction. For simplicity, only microscopic terms arising from binary collision and coupling to the solvent density fluctuation are included in the formalism. The equilibrium structural information functions of the polymer nanocomposites required by mode-coupling theory are calculated on the basis of polymer reference interaction site model with Percus-Yevick closure. The effect of nanoparticle size and that of the polymer size are clarified explicitly. The structural functions, the friction kernel, as well as the diffusion coefficient show a rich variety with varying nanoparticle radius and polymer chain length. We find that for small nanoparticles or short chain polymers, the characteristic short time non-Markov diffusion dynamics becomes more prominent, and the diffusion coefficient takes longer time to approach asymptotically the conventional diffusion constant. This constant due to the microscopic contributions will decrease with the increase of nanoparticle size, while increase with polymer size. Furthermore, our result of diffusion constant from mode- coupling theory is compared with the value predicted from the Stokes-Einstein relation. It shows that the microscopic contributions to the diffusion constant are dominant for small nanoparticles or long chain polymers. Inversely, when nanonparticle is big, or polymer chain is short, the hydrodynamic contribution might play a significant role.

Safety evaluation of a vehicle–bridge interaction system using the pseudo-excitation method

A method for analysing the vehicle-bridge interaction system with enhanced objectivity is proposed in the paper, which considers the time-variant and random characteristics and allows finding the power spectral densities(PSDs) of the system responses directly from the PSD of track irregularity. The pseudo-excitation method is adopted in the proposed framework, where the vehicle is modelled as a rigid body and the bridge is modelled using the finite element method. The vertical and lateral wheel-rail pseudo-excitations are established assuming the wheel and rail have the same displacement and using the simplified Kalker creep theory, respectively. The power spectrum function of vehicle and bridge responses is calculated by history integral. Based on the dynamic responses from the deterministic and random analyses of the interaction system, and the probability density functions for three safety factors(derailment coefficient, wheel unloading rate, and lateral wheel axle force) are obtained, and the probabilities of the safety factors exceeding the given limits are calculated. The proposed method is validated by Monte Carlo simulations using a case study of a high-speed train running over a bridge with five simply supported spans and four piers.

Study of velocity effects on parachute inflation performance based on fluid-structure interaction method

The inflation of a five-ring cone parachute with the airflow velocity of 18 m/s is studied based on the simplified arbitrary Lagrange Euler （SALE）/fluid-structure interaction （FSI） method. The numerical results of the canopy shape, stability, opening load, and drag area are obtained, and they are well consistent with the experimental data gained from wind tunnel tests. The method is then used to simulate the opening process under different velocities. It is found that the first load shock affected by the velocity often occurs at the end of the initial inflation stage. For the first time, the phenomena that the inflation distance proportion coefficient increases and the dynamic load coefficient decreases, respectively, with the increase in the velocity are revealed. The above proposed method is competent to solve the large deformation problem without empirial coefficients, and can collect more space-time details of fluid-structure-motion information when it is compared with the traditional method.

Electron impact excitation rate coefficients of N II ion

This paper calculates the electron impact excitation rate coefficients from the ground term 2s^22p^2 3p to the excited terms of the 2s^22p^2, 2s^2p^3, 2s^22p3s, 2s^22p3p, and 2s^22p3d configurations of N II. In the calculations, multiconfiguration Dirac-Fork wave functions have been applied to describe the target-ion states and relativistic distorted-wave calculation has been performed to generate fine-structure collision strengths. The collision strengths are then averaged over a Maxwellian distribution of electron velocities in order to generate the effective collision strengths. The calculated rate coefficients are compared with available experimental and theoretical data, and some good agreements are found for the outer shell electron excitations. But for the inner shell electron excitations there are still some differences between the present calculations and available experiments.

FPGA Implementation of Extended Kalman Filter for Parameters Estimation of Railway Wheelset

It is necessary to know the status of adhesion conditions between wheel and rail for efficient accelerating and decelerating of railroad vehicle.The proper estimation of adhesion conditions and their real-time implementation is considered a challenge for scholars.In this paper,the development of simulation model of extended Kalman filter(EKF)in MATLAB/Simulink is presented to estimate various railway wheelset parameters in different contact conditions of track.Due to concurrent in nature,the Xilinx®System-on-Chip Zynq Field Programmable Gate Array(FPGA)device is chosen to check the onboard estimation ofwheel-rail interaction parameters by using the National Instruments(NI)myRIO®development board.The NImyRIO®development board is flexible to deal with nonlinearities,uncertain changes,and fastchanging dynamics in real-time occurring in wheel-rail contact conditions during vehicle operation.The simulated dataset of the railway nonlinear wheelsetmodel is tested on FPGA-based EKF with different track conditions and with accelerating and decelerating operations of the vehicle.The proposed model-based estimation of railway wheelset parameters is synthesized on FPGA and its simulation is carried out for functional verification on FPGA.The obtained simulation results are aligned with the simulation results obtained through MATLAB.To the best of our knowledge,this is the first time study that presents the implementation of a model-based estimation of railway wheelset parameters on FPGA and its functional verification.The functional behavior of the FPGA-based estimator shows that these results are the addition of current knowledge in the field of the railway.

Determination of Integrated Molar Absorption Coefficients for Gaseous Phenol Infrared Bands and Influence of Water Vapor on Their Values

The integrated molar absorption coefficients for ν(OH) (3655 cm-1), δ(OH) (Q branch at 1176 cm-1 or whole bands), [ν(CCring) + δ(OH)] (Q branch at 1344 cm-1 or whole bands) and γ(CH) (752 cm-1) were determined at 342 K, by recording infrared spectra of pure gaseous phenol at different partial pressure (from 0 to 33 Pa). The integrated molar absorption coefficients (ε) values were obtained with a good reproducibility and the relative uncertainty on the given values is below 2%. The influence of water on the integrated molar absorption coefficients of phenol has been investigated in a large range of nwater/nphenol values (from 0.5 to 6.1 and from 44 to 94) using distinct setups. The infrared spectra of a gas mixture containing a constant amount of phenol and different amount of water were recorded (closed cell) whereas in dynamic condition (under flow) the water partial pressure was kept constant at 1.3 kPa and the phenol partial pressure was increased from 0 to 30 Pa. It is here demonstrated that, at 342 or 355 K, the presence of water does not affect the epsilon values of δ(OH) and [ν(CCring) + δ(OH)] bands.

Impact of Surface Exchange Coefficients and Sea Surface Cooling on Tropical Cyclone Simulation

The surface flux exchange associated with the exchange coefficients and upper ocean conditions is essential to the development of tropical cyclones(TCs).Using the Weather Research and Forecasting(WRF)model,the present study has investigated the impact of exchange coefficients and ocean coupling during Super Typhoon Saomai(2006).Firstly,two experiments with different formula of roughness are conducted.The experiment with the Donelan formula for drag coefficient(C_(d))and ramped formula for enthalpy coefficient(C_(k))can simulate stronger intensity compared to other experiments due to the increased surface wind and enthalpy fluxes.That is because the new formulas allows for a smaller C_(d)and larger C_(k)in the high wind regime than the former formulas did.Moreover,two coupled simulations between WRF and a one-dimensional ocean model are conducted to examine the feedback of sea surface cooling to the TC.In the experiments with a horizontal uniform mixed layer depth of 70 m,the sea surface cooling is too weak to change the evolution of TC.While in the experiment with an input mixed layer calculated using the Hybrid Coordinate Ocean Model(HYCOM)data,the significant sea surface cooling induces obvious impact on TC intensity and structure.Under the negative feedback of sea surface cooling,the sensible and latent heat fluxes decreases,especially in the right part of Saomai(2006).The negative feedback with coupled ocean model plays a vital role in simulating the intensity and structure of TC.

The Research of Spin-Orbital Interaction in Intermetallic Compounds of System Gd-In on Paramagnetic Area

Normal,R0,and anomalous,RS,components of the Hall coefficient are determined from the results of experimental investigations of temperature dependences of the Hall coefficient,magnetic susceptibility,and specific electrical resistance for intermetallic Gd3In,Gd3In5 and GdIn3 compounds.Effective parameters of spin-orbital interactionλSO of intermetallic compounds are calculated from anomalous components RS of the Hall coefficient and specific electrical resistance.The results calculated for the band parameters and effective parameters of spin-orbital interactionλSO for Gd-In system intermetallides coincide by orders of magnitude with the results obtained from the optical spectra of pure REMs(rare-earth metals).

一种浮式梳式防波堤的消浪性能试验研究

针对一种新型的浮式梳式防波堤的消浪性能进行模型试验研究,试验模型采用固定结构形式,分析相对宽度、相对波高、水流速度和不规则波等因素对透射系数、反射系数和耗散系数的影响。研究结果表明:浮式梳式防波堤的消浪性能较为稳定,在波长较大的情况下,该型防波堤的消浪性能优于相同尺寸的方箱式防波堤;当相对宽度为0.20~0.27时,透射系数能达到最小值;在波与流共同作用下,同向水流会削弱波浪的消浪性能;在相同波浪参数下,不规则波的透射系数要略高于规则波的透射系数。