Large-scale two-dimensional nonlinear FE analysis on PGA amplification effect with depth and focusing effect of Fuzhou Basin

Based on the explicit finite element(FE) method and platform of ABAQUS,considering both the inhomogeneity of soils and concave-convex fluctuation of topography,a large-scale refined two-dimensional(2D) FE nonlinear analytical model for Fuzhou Basin was established.The peak ground motion acceleration(PGA) and focusing effect with depth were analyzed.Meanwhile,the results by wave propagation of one-dimensional(1D) layered medium equivalent linearization method were added for contrast.The results show that:1) PGA at different depths are obviously amplified compared to the input ground motion,amplification effect of both funnel-shaped depression and upheaval areas(based on the shape of bedrock surface) present especially remarkable.The 2D results indicate that the PGA displays a non-monotonic decreasing with depth and a greater focusing effect of some particular layers,while the 1D results turn out that the PGA decreases with depth,except that PGA at few particular depth increases abruptly; 2) To the funnel-shaped depression areas,PGA amplification effect above 8 m depth shows relatively larger,to the upheaval areas,PGA amplification effect from 15 m to 25 m depth seems more significant.However,the regularities of the PGA amplification effect could hardly be found in the rest areas; 3) It appears a higher regression rate of PGA amplification coefficient with depth when under a smaller input motion; 4) The frequency spectral characteristic of input motion has noticeable effects on PGA amplification tendency.

Two-dimensional analysis of a negative differential conductance gate transistor as a THz emitter

We investigate plasma modes in a transistor including a negative differential conductance in the gate. The analytical results show that the plasma wave generation is substantially influenced by the lateral direction （width of the transistor）, gate leakage current and ＇viscosity. The injection from the gate （opposed to the gate leakage current） can improve the plasma oscillations and their amplitude with respect to ordinary transistors. We also estimate, which to our best knowledge has been derived for the first time, the total power emitted by the transistor and the emitted pattern which qualitatively gives reasonable agreement with the experimental data. The results show that the radiated power depends on various parameters such as drift velocity, momentum relaxation time, gate leakage current and especially the lateral direction. A negative gate current enhances the power while the gate leakage current decreases the power.

Hydroisomerization of n-Pentane over Zn-Fe-S2O8-2/ZrO2-Al2O3 Superacid Catalyst: Activity, Surface Analysis and the Investigation of Deactivation and Regeneration

The Zn and Fe modified /ZrO2-Al2O3 catalyst (Zn-Fe-SZA) was prepared and mechanisms of deactivation and methods for regeneration of as-prepared catalyst were explored with n-pentane isomerization as a probe reaction. The results indicated that the isopentane yield of the fresh Zn-Fe-SZA-F catalyst was about 57% at the beginning of the run, and declined gradually to 50% within 1500 min, then fell rapidly from 50% to 40% between 1500 and 2500 minutes. The deactivation of Zn-Fe-SZA catalyst may be caused by carbon formation on surface of the catalyst, sulfate group attenuation owing to reduction by hydrogen, removal of sulfur species and the loss of strong acid sites. It was found that the initial catalytic activity over Zn-Fe-SZA-T catalyst was 48%, which recovered by 84.3% as compared to that of fresh catalyst (57%). However, it showed a sharp decrease in isopentane yield from 48% to 29% within 1500 minutes, showing poor stability. This is associated to the loss of acidity caused by removal of sulfur species cannot be basically restored by thermal treatment. Resulfating the calcined catalyst could improve the acidity of catalyst significantly, especially strong acid sites, as compared with the calcined sample. The improved stability of the resulfated catalyst can be explained by: 1) eliminaton of carbon deposition to some extent by calcination process, 2) formation of improved acidic nature by re-sulfation, favoring isomerization on acidic sites, 3) restructuring of the acid and metal sites via the calcination-re-sulfation procedure.

TWO-DIMENSIONAL STRESS WAVE ANALYSIS IN INCOMPRESSIBLE ELASTIC SOLIDS

Two-dimensional stress wares in n general incompressible elastic solid are investigated. First, baxic equations for simple wares and shock waves are presented for a general strain energy junction. Then the characteristic ware speeds and the associated characteristic vectors are deduced. It is shown that there usually exist two simple waves and two shock wares. Finally, two examples are given for the case of plane strain deformation and antiplane strain deformation, respectively. It is proved that, in the case of plane strain deformation, the oblique reflection problem of a plane shock is not solvable in general.

Further studies on stability analysis of nonlinear Roesser-type two-dimensional systems

This paper is concerned with further relaxations of the stability analysis of nonlinear Roesser-type two-dimensional （2D） systems in the Takagi-Sugeno fuzzy form. To achieve the goal, a novel slack matrix variable technique, which is homogenous polynomially parameter-dependent on the normalized fuzzy weighting functions with arbitrary degree, is developed and the algebraic properties of the normalized fuzzy weighting functions are collected into a set of augmented matrices. Consequently, more information about the normalized fuzzy weighting functions is involved and the relaxation quality of the stability analysis is significantly improved. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed result.

Numerical solutions of two-dimensional nonlinear integral equations via Laguerre Wavelet method with convergence analysis

In this paper,the approximate solutions for two different type of two-dimensional nonlinear integral equations:two-dimensional nonlinear Volterra-Fredholm integral equations and the nonlinear mixed Volterra-Fredholm integral equations are obtained using the Laguerre wavelet method.To do this,these two-dimensional nonlinear integral equations are transformed into a system of nonlinear algebraic equations in matrix form.By solving these systems,unknown coefficients are obtained.Also,some theorems are proved for convergence analysis.Some numerical examples are presented and results are compared with the analytical solution to demonstrate the validity and applicability of the proposed method.

Stability analysis of nonlinear Roesser-type two-dimensional systems via a homogenous polynomial technique

This paper is concerned with the problem of stability analysis of nonlinear Roesser-type two-dimensional （2D） systems. Firstly, the fuzzy modeling method for the usual one-dimensional （1D） systems is extended to the 2D ease so that the underlying nonlinear 2D system can be represented by the 2D Takagi Sugeno （TS） fuzzy model, which is convenient for implementing the stability analysis. Secondly, a new kind of fuzzy Lyapunov function, which is a homogeneous polynomially parameter dependent on fuzzy membership functions, is developed to conceive less conser- vative stability conditions for the TS Roesser-type 2D system. In the process of stability analysis, the obtained stability conditions approach exactness in the sense of convergence by applying some novel relaxed techniques. Moreover, the obtained result is formulated in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, a numerical example is also given to demonstrate the effectiveness of the proposed approach.

An Analysis of Two-Dimensional Image Data Using a Grouping Estimator

Machine learning methods, one type of methods used in artificial intelligence, are now widely used to analyze two-dimensional (2D) images in various fields. In these analyses, estimating the boundary between two regions is basic but important. If the model contains stochastic factors such as random observation errors, determining the boundary is not easy. When the probability distributions are mis-specified, ordinal methods such as probit and logit maximum likelihood estimators (MLE) have large biases. The grouping estimator is a semiparametric estimator based on the grouping of data that does not require specific probability distributions. For 2D images, the grouping is simple. Monte Carlo experiments show that the grouping estimator clearly improves the probit MLE in many cases. The grouping estimator essentially makes the resolution density lower, and the present findings imply that methods using low-resolution image analyses might not be the proper ones in high-density image analyses. It is necessary to combine and compare the results of high- and low-resolution image analyses. The grouping estimator may provide theoretical justifications for such analysis.

3D FE Analysis of Thermal Behavior of Billet in Rod and Wire Hot Continuous Rolling Process

An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.

Energy Transfer Mechanism and Probability Analysis of Submarine Pipe Laterally Impacted by Dropped Objects

Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine pipe impacted by dropped objects, series of experiments are designed and carried out. The effective yield strength is deduced to make the quasi-static analysis more reliable, and the normal distribution of energy transfer ratio caused by lateral impact on pipes is presented by statistic analysis of experimental results based on the effective yield strength, which provides experimental and theoretical basis for the risk analysis of submarine pipe system impacted by dropped objects. Failure strains of pipe material are confirmed by comparing experimental results with finite element simulation. In addition, impact contact area and impact time are proved to be the major influence factors of energy transfer by sensitivity analysis of the finite element simulation.

Determination of Fe and Zn contents and distributions in natural sphalerite/marmatite by various analysis methods

The contents of Fe and Zn in natural sphalerite samples were determined by chemical titration and spectroscopic techniques(portable X-ray fluorescence(P-XRF) spectrometry, electron probe microanalysis with energy dispersive spectroscopy(EPMA-EDS), electron probe microanalysis with wavelength dispersive spectroscopy(EPMA-WDS), and time-of-flight secondary ion mass spectrometry(To F-SIMS)). Besides, the distribution of Fe and Zn in sphalerite samples was analyzed by imaging EPMA-WDS and imaging To F-SIMS. The results show that Fe and Zn contents determined by each spectroscopic technique have good linearity with those determined by chemical titration(R^2>0.77), and the R^2 values of Fe are generally greater than those of Zn. The imaging analysis results revealed that Fe and Zn are not uniformly distributed in the sphalerite.

Topology Optimization of Sound-Absorbing Materials for Two-Dimensional Acoustic Problems Using Isogeometric Boundary Element Method

In this work,an acoustic topology optimizationmethod for structural surface design covered by porous materials is proposed.The analysis of acoustic problems is performed using the isogeometric boundary elementmethod.Taking the element density of porousmaterials as the design variable,the volume of porousmaterials as the constraint,and the minimum sound pressure or maximum scattered sound power as the design goal,the topology optimization is carried out by solid isotropic material with penalization(SIMP)method.To get a limpid 0–1 distribution,a smoothing Heaviside-like function is proposed.To obtain the gradient value of the objective function,a sensitivity analysis method based on the adjoint variable method(AVM)is proposed.To find the optimal solution,the optimization problems are solved by the method of moving asymptotes(MMA)based on gradient information.Numerical examples verify the effectiveness of the proposed topology optimization method in the optimization process of two-dimensional acoustic problems.Furthermore,the optimal distribution of sound-absorbingmaterials is highly frequency-dependent and usually needs to be performed within a frequency band.

Environmental Analysis with 2D Transition-Metal Dichalcogenide-Based Field-Effect Transistors

Field-effect transistors(FETs)present highly sensitive,rapid,and in situ detection capability in chemical and biological analysis.Recently,two-dimensional(2D)transition-metal dichalcogenides(TMDCs)attract significant attention as FET channel due to their unique structures and outstanding properties.With the booming of studies on TMDC FETs,we aim to give a timely review on TMDCbased FET sensors for environmental analysis in different media.First,theoretical basics on TMDC and FET sensor are introduced.Then,recent advances of TMDC FET sensor for pollutant detection in gaseous and aqueous media are,respectively,discussed.At last,future perspectives and challenges in practical application and commercialization are given for TMDC FET sensors.This article provides an overview on TMDC sensors for a wide variety of analytes with an emphasize on the increasing demand of advanced sensing technologies in environmental analysis.

基于纳米压痕反向分析的Fe-32Ni超因瓦合金介观尺度弹塑性本构关系

采用纳米压痕技术和电子背散射衍射分析技术对Fe-32Ni超因瓦合金不同取向的晶粒进行了测试,得到了材料在(001)、(101)和(111)取向下的弹性模量和硬度。同时基于量纲分析提出了一种改进的反向算法,并结合有限元仿真对Fe-32Ni超因瓦合金的纳米压痕过程进行了反向分析和计算,通过纳米压痕实验曲线与仿真曲线的对比,最终获得材料在(001)、(101)和(111)取向下的应力应变关系,结果表明:(001)取向下晶粒的屈服强度最高,(101)取向下晶粒的屈服强度最低。此外,(101)和(111)取向的晶粒屈服后的应力-应变曲线变化趋势较为一致,而(001)取向下的应力-应变曲线变化较为平缓,材料在不同取向下的力学响应具有明显的各向异性。

Thermodynamic analysis of Na−S−Fe−H_(2)O system for Bayer process

Thermodynamic diagrams of Na−S−Fe−H_(2)O system were constructed to analyze the behavior of sulfur and iron in the Bayer process.After digestion,iron mainly exists as Fe_(3)O_(4) and Fe_(2)O_(3) in red mud,and partial iron transfers into solution as Fe(OH)_(3)^(−),HFeO_(2)^(−),Fe(OH)_(4)^(−)and Fe(OH)_(4)^(2−).The dominant species of sulfur is S^(2−),followed by SO_(4)^(2−),and then SO_(3)^(2−)and S_(2)O_(3)^(2−).The thermodynamic analysis is consistent with the iron and sulfur species distribution in the solution obtained by experiments.When the temperature decreases,sulfur and iron can combine and precipitate.Controlling low potential and reducing temperature are beneficial to removing them from the solution.XRD patterns show that NaFeS_(2)·2H_(2)O,FeS and FeS_(2) widely appear in red mud and precipitates of pyrite and high-sulfur bauxite digestion solution.Thermodynamic analysis can be utilized to guide the simultaneous removal of sulfur and iron in the Bayer process.

Species distribution of polymeric aluminium ferrum——timed complexation colorimetric analysis method of Al-Fe-Ferron

The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexatian colorimetric analysis method of Al-Fe-ferron in view of the total concentration of {AI + Fe} was then established to determine the species distribution of polymeric Al-Fe. The testing wavelength was recommended at 362 net and the testing pH value was 5. With a comparison of the ratios of n(Al)/n(Fe), the standard adsorption curves of the polymeric Al-Fe solutions were derived from the experimental results. Furthermore, the solutions' composition were carious in both the molar n(Al)/n(Fe) ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total ( Al + Fe which ranged from 10(-5) to 10(-4) mol/L..

Al-5%Fe-xNi合金的组织演变与热学性能

通过传统铸造法制备Al-5%Fe-xNi(x=0%,1.5%,5%,7.5%,10%,质量分数,下同)合金,观察Ni加入后合金中初生相的形态和尺寸变化,分析合金凝固过程的转变情况以及Ni加入对初生相和共晶组织的影响,探讨Ni含量对合金组织及热学性能的影响。结果表明:随着Ni含量的增加,合金中的初生相由不规则块状转变为针状。当Ni含量超过5%时,共晶组织减少,初生相转变为规则排列的Al_(9)FeNi相。Ni的加入显著改变合金的凝固过程,使得初生相析出反应由L→Al_(13)Fe_(4)转变为L→Al_(9)FeNi或L+Al13Fe4→Al9FeNi,共晶析出反应由L→α-Al+Al_(13)Fe_(4)逐渐转变为L+Al_(13)Fe_(4)→α-Al+Al9FeNi和L→Al3Ni+α-Al+Al9FeNi。随着Ni含量的增加,析出相体积分数增大,合金的热导率和热膨胀系数随之降低,热膨胀系数从Al-5%Fe的19.9×10^(-6)K^(-1)(@25~200℃)降至Al-5%Fe-10%Ni的17.6×10^(-6)K^(-1)(@25~200℃)。采用通用有效介质理论(GEMT)模型和修正的Turner模型分别对合金的热导率和热膨胀系数进行预测,发现模拟值与实验值吻合较好。

以研促教:利用荧光探针检测Fe^(2+)的实验设计

本文以荧光探针的设计合成和监测亚铁离子(Fe^(2+))应用于分析化学拓展实验教学为主题,介绍了一种新型的荧光探针DCM-Fe,其通过引入N-氧化物基团有效抑制了分子内电荷转移的发生,实现了对Fe^(2+)荧光“turn on”型检测。本文还阐述了在实验教学中,通过本实验的设计和实施,学生可以深入理解荧光探针的设计合成原理和荧光检测技术的应用,在实践中掌握荧光探针的合成、分析和应用,并培养了学生的实验技能和创新意识。本实验教学可为分析化学实验教学的拓展提供一种新思路和方法。

Non-steady FE analysis on porthole dies extrusion of aluminum harmonica-shaped tube

According to the rigid-viscoplasticity finite element method,the porthole die extrusion process of an aluminum harmonica-shaped tube was successfully simulated based on software Deform-3D. The distribution of stress field,effective strain field,velocity field and temperature field during the extrusion process were discussed and the metal flow in welding extrusion was analyzed. The simulation results show that the material flow velocities in the bearing exit are non-uniform with the originally designed die and the forepart of the profile is not neat or even. Aiming at solving this problem,the modification method of die structure was improved. The result shows that the uniform material flow velocities in the die exit and a perfect extruded are obtained by modification bearing length.

EFFECTS OF NITRIDING TEMPERATURE ON MAGNETIC PROPERTIES OF MELT-SPUN Pr1.4Fe10.5Mo1.5Nx AND ITS PHASE ANALYSIS

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