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Design the wheel mold according to the cross-sectional view of the lightweight aluminum alloy wheel profile, determine the length of its working belt and use HyperXtrude software to simulate it, verify the rationality of the working belt design, analyze the flow velocity and temperature of the mold outlet, and determine the 7075 aluminum alloy The alloy wheel profile is most reasonable to be produced on a 10 MN extruder. Finally, the optimized working belt length is used for production. The quality of hot extrusion profile is qualified, which proves the accuracy of the simulation.

Q235 steel components have poor corrosion resistance and are susceptible to erosion by corrosive media, so they are generally passivated before being put into service. This paper investigates the corrosion behaviour and corrosion mechanism of passivated Q235 steel in atmospheric environments through macro and micro morphological characterisation and electrochemical simulation analysis.

In order to improve the quality of welded joints and increase the service life of pipelines, ABAQUS finite element software was used to simulate the temperature field of 18,4 mm thick X80 pipeline steel in multi-layer and multi pass welding. The peak temperature of different passes was compared, and the change trend of temperature field in the welding process was obtained,. The results show that the peak temperature of the weld and its adjacent areas is higher, and the peak temperature of the weld center is the highest. Due to the fast welding speed, the heat cannot be transferred to other areas in time, resulting in uneven heating of the entire test panel.

Q345C steel is welded under two different pre-welding heating methods of traditional flame heating and ceramic sheet heating. The finite element analysis of the butt joint weldment by ABAQUS software is used to summarize the law of welding deformation and compare the welding quality under different pre-welding heating methods according to the residual stress and deformation trend of the welding joint weld. The results show that the main stress after welding is concentrated in the weld seam and the surrounding area. The residual stress after welding after the heating and welding of the ceramic sheet is significantly less than the residual stress after the traditional flame heating welding, and the welding after the heating of the ceramic sheet can obtain better welding quality.

According to the practical engineering application, three-dimensional modeling of electric hoist and I-beam track is carried out, and the model is simplified to determine the electric hoist load, roller acceleration and speed, and the Abaqus software is used to simulate, analyze the simulation results, observe the actual maximum load under the track stress and strain to meet the requirements, calculate the allowable stress, Observe whether it exceeds the allowable stress and whether plastic deformation occurs. If the numerical simulation results of stress and strain are within the safety requirements, the project can be implemented.

In this study, a 72-h neutral salt spray test was conducted on two low-carbon alloy steels and their corrosion kinetic equations were constructed, and tensile tests were conducted on specimens with different corrosion cycles to evaluate the mechanical properties of the two experimental steels. The test results showed that the corrosion resistance of TZ750MS was better than that of H750MS during the whole test cycle; however, the predicted results of the corrosion kinetic equation showed that the corrosion resistance of TZ750MS was lower than that of H750MS after 144 h. The tensile test results showed that the strength of both steels did not change substantially after corrosion, and the tensile stress-strain diagram showed that the specimens would fracture earlier after passing through the plastic deformation zone .

In order to meet the requirements for the quality of steel structure welding projects in severe cold areas, reasonable and effective technical research and welding scheme improvement are carried out for welding in low temperature environments. Based on ABAQUS software to simulate different welding conditions, mainly for welding after traditional flame heating and ceramic sheet heating in low temperature environment, the corresponding temperature field is obtained. Compared with the actual welding results, it is concluded that the weldment welded after heating with ceramic sheet is of better quality, fully verify the accuracy of welding simulation, optimize process design, shorten the time required for practical inspection accumulation.

Hot forging forming of railway wagon bogie adapter is a new railway wagon bogie adapter processing technology. In this paper, a hot forging die for railway wagon bogie adapter was designed, and the forming quality were analyzed by using DEFORM-3D software. Then, the feasibility of the process was verified by experiments. It was found that using this mold can eliminate the defects such as loose as-cast in metal smelting process, optimize the microstructure, forging products with good density, product quality and other characteristics of stability.

In order to accurately predict the flow stress of Q345B steel at high temperature, the Q345B steel was subjected to a hot compression test on the Gleeble-1500D thermal simulation test machine at a deformation temperature of 1 173,15~1 373,15 K and a strain rate of 0,01~10 s-1. Through the obtained true stress-strain curve, strain factors are introduced into the Arrhenius equation to establish a more accurate strain-coupled constitutive model. The results show that the correlation coefficient of the Arrhenius model considering strain compensation is 0,993, and the average absolute error is 4,59 %, which can accurately predict the flow stress. The experimental data and the calculated prediction curve fit well, which verifies the feasibility of the model.

To obtain the exact mechanical properties of TC4 titanium alloy, the compression experiments on TC4 titanium alloy at different strain rates (10-2,10-3,10-4 s-1) were performed at room-temperature on the MTS-810 electrohydraulic servo material testing machine. The data of TC4 titanium alloy compression experiments at different rates were obtained. And furthermore Johnson-Cook constitutive model is established. Due to different conditions, the equation is simplified, the constitutive parameters are obtained by step-by-step estimation method, and the Johnson- Cook (JC) constitutive model of TC4 titanium alloy at room temperature is established. The prediction results of the model were compared with the experimental data, the prediction curve is in good agreement, which verifies the feasibility of the model.

In the process of contemporary industrial pipeline installation, most pipelines must be cleaned before being put into use due to production and operation process requirements. This paper takes the offline trough cleaning of pipelines as the research object, and explores the evolution process of the metal microstructure under this cleaning method and the best cleaning conditions under the influence of the three factors of concentration, temperature and time.

In order to obtain the accurate mechanical properties of 7075 aluminum alloy, the Gleeble-1500D thermal simulation test machine was used to perform compression test on 7075 aluminum alloy. The deformation temperature range is 490 °C~560 °C, and the strain rate is 0,001 s-1~1 s-1. At present, for the high temperature thermal compression process, the Arrhenius constitutive model with strain compensation is usually used. The results show that the correlation coefficient of the Arrhenius constitutive model of 7075 aluminum alloy with strain compensation is 0,9894, and the average relative error is 5,6 %, realizing the fitting of flow stress and prediction, verified the feasibility of the model.

The downhole expansion process of the expansion tube is the dynamic deformation process of the expansion tube metal material at different temperatures. In this paper, the dynamic tensile test is used to measure the dynamic tensile stress-strain curve of low-carbon alloy steel in the temperature range of 25 – 300 °C. upon analyzed the dynamic tensile test results, with the strain rate factor Z and McCormick physical model, the paper set up low carbon alloy steel constitutive equation of underground temperature field. The calculation results of the Sellars creep equation are compared with the residual stress value after expansion in the finite element analysis of the solid steel pipe expansion to verify the actual application reliability of the steel for the expansion pipe with high expansion rate.

Thermal compression test temperature ranged from 800 to 1 200 °C, the strain rate ranged from 0,01 to 10 s-1, and the deformation degree was 60 % of engineering strain, the deformation behavior of 42CrMo gear steel was studied. As the deformation temperature increases and the strain rate decreases, the stress decreases significantly. By polynomial fitting the relationship between strain(0,05 – 0,9, at intervals of 0,05) and material constants, the straincompensationed Arrhenius constitutive equation for 42CrMo gear steel is established. The correlation coefficient between the experimental data and the predicted data reached 0,9925. This shows that the Arhenius constitutive equation has high accuracy in predicting steel 42CrMo for gear.

The 3Cr23Ni8Mn3N heat-resistant steel was subjected to isothermal constant strain rate compression experiments using a Gleeble - 1 500D thermal simulator. The thermal deformation behavior in the range of deformation temperature 1 000 - 1 180 °C and strain rate 0,01 - 10 s-1 was studied. Based on experimental data, the stress-strain curves of 3Cr23Ni8Mn3N were established. And the constitutive relation of BP neural network (3 × 10 × 10 × 1) was constructed. The flow stress was predicted and compared by the ANN constitutive model. The correlation coefficient (R) is 0,999, and the average relative error (AARE) is 0,697 %. The results show that the ANN constitutive model has high accuracy for predicting the thermal deformation behavior of 3Cr23Ni8Mn3N. The model can provide a good reference value for thermal processing.

Rationale: Discordant alternans, a phenomenon in which the action potential duration (APDs) and/or intracellular calcium transient durations (CaDs) in different spatial regions of cardiac tissue are out of phase, present a dynamical instability for complex spatial dispersion that can be associated with long-QT syndrome (LQTS) and the initiation of reentrant arrhythmias. Because the use of numerical simulations to investigate arrhythmic effects, such as acquired LQTS by drugs is beginning to be studied by the FDA, it is crucial to validate mathematical models that may be used during this process. Objective: In this study, we characterized with high spatio-temporal resolution the development of discordant alternans patterns in transmembrane voltage (Vm) and intracellular calcium concentration ([Cai]+2) as a function of pacing period in rabbit hearts. Then we compared the dynamics to that of the latest state-of-the-art model for ventricular action potentials and calcium transients to better understand the underlying mechanisms of discordant alternans and compared the experimental data to the mathematical models representing Vm and [Cai]+2 dynamics. Methods and Results: We performed simultaneous dual optical mapping imaging of Vm and [Cai]+2 in Langendorff-perfused rabbit hearts with higher spatial resolutions compared with previous studies. The rabbit hearts developed discordant alternans through decreased pacing period protocols and we quantified the presence of multiple nodal points along the direction of wave propagation, both in APD and CaD, and compared these findings with results from theoretical models. In experiments, the nodal lines of CaD alternans have a steeper slope than those of APD alternans, but not as steep as predicted by numerical simulations in rabbit models. We further quantified several additional discrepancies between models and experiments. Conclusions: Alternans in CaD have nodal lines that are about an order of magnitude steeper compared to those of APD alternans. Current action potential models lack the necessary coupling between voltage and calcium compared to experiments and fail to reproduce some key dynamics such as, voltage amplitude alternans, smooth development of calcium alternans in time, conduction velocity and the steepness of the nodal lines of APD and CaD.

MicroRNAs (miRs) are key posttranscriptional regulators of gene expression in all eukaryotic cells and have a vital role in the evolution of hypertension and cardiovascular remodelling and, therefore, have emerged as potential biomarkers for cardiovascular disease. We assessed 240 participants, including 60 healthy volunteers with normal carotid intima-media thickness (nCIMT), 60 healthy volunteers with increased CIMT (iCIMT), 60 hypertensive patients with nCIMT and 60 hypertensive patients with iCIMT. All patients underwent measurements of CIMT, carotid-femoral pulse wave velocity (cfPWV) and ambulatory blood pressure (BP) monitoring. Plasma miR-92a expression was quantified by real-time reverse transcription PCR. Correlations between miR-92a expression and BP parameters, CIMT and cfPWV were assessed using the Spearman correlation coefficient. We observed the lowest miR-92a expression (24.59±1.30 vs 27.76±2.13 vs 29.29±1.89 vs 33.76±2.08; P

We analytically and numerically investigate the ground state of the spin-orbit coupled spin-1 Bose-Einstein condensates in an external parabolic potential. When the spin-orbit coupling strength $\kappa$ is comparable with that of the trapping potential, the density distribution centers of different components of the spinor condensate deviate evidently from the trap center in the plane wave and stripe phases. When $\kappa\gg1$, the magnitude of this deviation decreases as $\kappa$ is getting larger and larger. Correspondingly, periphery half-skyrmions textures arise. This deviation can be reflected by the non-uniform magnetic moment in the $z$ direction, $\mathcal{F}_z$. With the manipulation of the external trap, the local magnitude of $\mathcal{F}_z$ can be increased evidently. This kind of increase of $\mathcal{F}_z$ is also observed in the square vortex lattice phase of the condensate., Comment: 7pages,8 figures

It is shown that the alkylation of toluene with ethylene to give p-ethyltoluene can be conducted selectively on small crystals (⩽ 1μ) of unmodified H-ZSM-5 zeolites to a level higher than that corresponding to a thermodynamic equilibrium composition. A comparison of the ethyltoluene isomers formed with H-Y and H-ZSM-5 zeolites at various conversions and temperatures indicates that p -ethyltoluene is preferentially formed in the channel intersections of the H-ZSM-5 zeolite, even during the initial alkylation step. The final ethyltoluene isomer composition is a result of competition between the rates of alkylation and isomerization and subsequent diffusional transport of individual isomers through the zeolite channels. Zeolite coking causes an apparent increase in the p -ethyltoluene selectivity; however, a more dramatic decrease in toluene conversion results in the formation of a considerably lower amount of p -ethyltoluene. This is caused by a partial blocking of the zeolite channel system.

We present a measurement of the induced proton polarization P-n in pi(0) electroproduction on the proton around the Delta resonance. The measurement was made at a central invariant mass and a squared four-momentum transfer of W=1231 MeV and Q(2)=0.126 GeV2/c(2), respectively. We measured a large induced polarization, P-n = -0.397 +/- 0.055 +/- 0.009. The data suggest that the scalar background is larger than expected from a recent effective Hamiltonian model. [S0556-2813(98)02012-3].

The first measurements of the induced proton polarization P-n for the C-12(e,e’(p) over right arrow) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w, q) approximate to (294 MeV, 756 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data fur the 1p(3/2) shelf. The data for the continuum suggest that both the 1s(1/2) shell and underlying l > 1 configurations contribute.

For the fatigue failure of 42CrMo, the tensile test was performed on the CT specimen at different load ratios using a fatigue tensile tester. Data on the fatigue crack growth rate of the material and the crack tip factor were obtained. Scanning electron microscopy (SEM) was used to observe the microstructure and crack initiation and propagation of fractures. The crack initiation and propagation path law during fatigue crack propagation were obtained. The fatigue crack life was calculated by Paris formula, and the fatigue crack growth test and microscopic observation were compared. The propagation law and fatigue crack life of different stages of crack propagation were analyzed. The results show that the stable propagation stage of fatigue crack propagation is the key stage to determine fatigue fracture, the rate of growth is related to the stress ratio.

Based on 28 year field data of Stipa bungeana community in arid, semi-arid, semi-humid areas of the Loess Plateau of Northwestern China, we studied species diversity and above ground biomass of S. bungeana community, analyzed the responses of above ground biomass to climate in different areas, and built a model of relationship between biomass and climatic factors. Results showed that there were significant differences for species diversity and above ground biomass among different sampling area. The species diversity range of S. bungeana was from 8.5 - 30.8 (ind/m2), and above ground biomass range was from 407.3 - 817.3 (g/m2) among studied area. The optimal distribution altitude range for S. bungeana is 1400 - 2000 m in arid area, 1200 - 1900 m in semi-arid area, and 600 - 1600 m in semi-humid area. Results also showed that the growth of S. bungeana was affected by different climatic factors, with rainfall as the major factor. Meanwhile, there was a close relationship between monthly biomass and rainfall during the growth stage. The models of monthly biomass and climate were built to compare the results and reveal the relationship between climatic factors and the growth of S. bungeana community.Key words: Stipa bungeana community, biomass model, species diversity, climatic factor, Loess Plateau.

The hot compression test was conducted in Gleeble-1 500D to study the hot flow stress behavior of AA6 111 aluminum alloy belonging to Al-Mg-Si series, at the deformation temperatures ranging from 350 to 500 °C and strain rates ranging from 0,01 s-1 to 1 s-1. And how the flow stress change with variation of strain, temperature and strain rate was investigated. The results show that flow stress increases with decreasing temperature and increasing strain rate; the AA6 111 is positive stain rate sensitive material; the main softening mechanism is dynamic recovery. Furthermore, constitutive equation considering the effect of strain was obtained based on Arrhenius equation. The predicted flow stress values well agree with the experimental results with some little aberration. The coefficient of association can be as high as 0,9 954, which shows high reference value for industry and simulation analysis.