电子束熔炼提纯钨中杂质脱除静态动力学研究

研究了电子束熔炼提纯钨过程中典型杂质的脱除,考察了电子束熔炼提纯钨的可行性,对电子束熔炼过程中的除杂动力学进行了分析,并确定了110、130、250 kW功率条件下杂质Fe、Si、Ti的脱除速率控制机制。结果表明:除Mo外,电子束熔炼对基体钨中各种杂质均有不同程度的脱除,其脱除率与饱和蒸气压差存在对应关系;通过分析并结合电子束熔炼实验,确定了Si、Fe、Ti在110 kW时的传质系数分别为0.21、0.56、0.11×10-4 m/s,在130 kW时的传质系数分别为0.83、3.04、1.78×10-4 m/s,在250 kW时的传质系数分别为0.36、2.37、1.48×10-4 m/s,表明其脱除速率控制机制均为液/气界面中的扩散。

一种热轧双相钢在γ和γ+α相区的静态软化动力学研究

对含 0 .1 9%碳的热轧双相钢分别在γ和γ +α相区进行双道次压缩试验 ,研究在不同变形温度和变形速率下钢的静态软化比随着间隙时间的变化规律。结果表明 ,在γ相区 ,随着变形温度的升高、变形速率的增加和间隙时间的延长 ,钢的静态软化比增加。在一定条件下 ,静态软化比可以达到 1 0 0 %。根据研究结果 ,对γ相区的静态再结晶动力学进行模型化。在γ +α相区 ,钢的静态软化比较低 ,它不仅受到变形温度、变形速率和间隙时间的影响 ,还受到两相组织组份的影响。

离子交换树脂对冰葡萄汁总酸和总酚的静态吸附动力学研究

该实验研究了D354树脂对冰葡萄汁总酸和总酚的静态吸附动力学模型。结果表明,随吸附温度的升高,D354树脂对冰葡萄汁总酸和总酚的吸附速率显著提高(P<0.05)。在0℃、10℃和20℃条件下,D354树脂对冰葡萄汁总酸的最大吸附量分别为151.69 mg/g、190.09 mg/g及222.16 mg/g;对冰葡萄汁总酚的最大吸附量分别为3.65 mg/g、4.20 mg/g及4.67 mg/g;D354树脂吸附冰葡萄汁总酸和总酚的过程符合拟二阶动力学模型(R^2>0.998 0),并确定了D354树脂对冰葡萄汁总酸和总酚的拟二阶动力学方程;利用W-M(WeberMorris)动力学模型对数据拟合(R^2>0.930 0),结果表明整个静态吸附过程受粒内扩散和液膜扩散共同控制。

八杆压力机机构的动力学研究

本文对八杆压力机机构的动态静力学进行了研究,将八杆机构分为三个模块,对每一个模块的各杆分别进行动力学分析,列出各杆力及力矩的平衡方程,并整理成矩阵的形式,通过求解矩阵方程即可求出各杆的受力情况,为八杆机构各构件的性能分析奠定理论基础。

飘带式子弹气动力工程计算方法

本文在试验与理论分析的基础上,建立了飘带—弹体组合体气动力计算的数学模型,导出了飘带式子弹气动力工程计算公式。计算结果表明与实验值是相当一致的,这说明本方法可行。

非静态种群动力学过程影响下的渔业资源评估与管理

科学有效的渔业资源评估与管理是实现渔业资源可持续开发和利用的重要保障。传统的渔业资源评估与管理基于不变性假设,认为关键种群动力学过程不随时间发生变化。随着气候变化和人类活动的影响,种群的关键动力学过程可能随时间发生系统性的变化,形成非静态种群动力学过程,并在很大程度上颠覆了传统的不变性假设。结合近年来国际相关领域的研究成果,系统地阐述了非静态种群动力学过程的形成机制以及其对渔业资源评估模型、生物学参考点和渔业管理理念的影响。分析认为,在非静态种群动力学过程影响下,渔业资源评估模型和生物学参考点都需要考虑到关键种群动力学过程的时间变化,需要通过引入外部环境变量或者随时间变化的种群动力学参数,来应对非静态种群动力学过程对资源评估与管理带来的影响。研究建议,基于弹性的渔业管理是我们未来应对非静态种群动力学过程、维持渔业社会-生态系统稳定和健康的重要发展方向。

盐酸文拉法辛药物树脂的制备及其静态交换特性的研究

目的制备盐酸文拉法辛药物树脂复合物,并考察在静态条件下影响药物树脂形成的因素。方法以强酸性阳离子交换树脂(001×7)为载体,在静态条件下考察了离子交换树脂的粒径、交换温度、树脂用量对药物树脂的制备即静态交换动力学特性的影响,并对交换动力学曲线进行拟合,考察了不同条件下的交换反应速率常数、平衡速率常数、活化能、反应热和熵值。结果树脂颗粒越小、反应温度越高,达到平衡所需时间越短。树脂用量越大,平衡时交换率越高。交换反应活化能约为52 kJ mol-1,且温度为293 K时,交换反应可自发正向进行。结论上述因素对药物树脂复合物的制备均有不同程度的影响。

5083铝合金静态再结晶行为研究

本文采用Gleeble热模拟实验、金相实验、硬度实验验,研究了热变形条件及热处理条件对5083铝合金静态再结晶行为的影响。研究结果表明:5083铝合金热变形过程中Zener-Hollomon参数值越大或变形程度越大,则合金在后续退火过程中的再结晶速率越大,再结晶后的晶粒尺寸越细小;热变形后的退火温度越高,则合金在退火过程中的再结晶速率越大,但退火温度对合金再结晶后的晶粒尺寸影响不明显;随着退火时间的延长,合金金相组织从纤维状转变为等轴状,进一步延长退火时间后晶粒将发生长大现象。根据实验结果建立了5083铝合金静态再结晶动力学方程。

6-氨基青霉烷酸在弱碱性阴离子树脂上的吸附研究

用静态法研究6-氨基青霉烷酸(6-APA)在弱碱性阴离子交换树脂D301和330上的吸附行为。在溶液pH为8.0,6-APA起始浓度介于1.5至20mg/mL条件下,测定25℃时D301树脂和330树脂的静态交换动力学曲线、吸附等温线,并求算D301树脂和330树脂的吸附等温线方程。分别用Langmuir型和Freundlich型方程对D301树脂和330树脂吸附等温线进行线性回归拟和,结果表明,6-APA在D301树脂和330树脂上的吸附更符合Langmuir型吸附。

Static and dynamic mechanical behaviour of ECO-RPC

Ecological reactive powder concrete (ECO-RPC) with small sized and differentvolume fraction steel fibers was prepared by substitution of ultra-fine industrial waste powder for50% to 60% cement by weight and replacement of ground fine quartz sand with natural fine aggregate.The effect of steel fiber volume fraction and curing ages on the static mechanical behaviour ofECO-RPC was studied. Using the split Hopkinson pressure bar technique, the dynamic mechanicalbehaviour of ECO-RPC was investigated under different strain rates. The results show that the staticmechanical behaviour of ECO-RPC increases with the increase of steel fiber volume fraction andcuring ages. The type of ECO-RPC with the substitution of 25% ultra-fine slag, 25% ultra-fine flyash and 10% silica fume is better than the others with compressive strength, flexural strength, andfracture energy more than 200 MPa, 60 MPa and 30 kJ/m^2, respectively. ECO-RPC has excellent strainrate stiffening effects under dynamic load. Its peak stress, peak strain and the area understrain-stress curve increase with the increase of strain rate. Its fracture pattern changes frombrittleness to toughness under high strain rates.

Static coarsening behavior of equiaxed α phase in Ti-8Al-1Mo-1V alloy

To get a deep understanding of the evolution behavior of equiaxedαphase in Ti−8Al−1Mo−1V alloy during annealing,its static coarsening mechanism was studied based on the calculations of coarsening exponent n and the activation energy forαboundary migration.The result of n=6 indicates a special coarsening mechanism of equiaxedαphase.The activation energy forαboundary migration is calculated to be 138 kJ/mol,which is close to the activation energy for grain growth of pureα-Ti.It is revealed that the coarsening of equiaxedαcan be mainly attributed to the self-diffusion of Ti atoms across theα/αboundaries.Based on the experimental findings,a static coarsening kinetics model of equiaxedαgrains in theα+βfield is established.At last,the effects of the coarsening behavior of equiaxedαon tensile properties were studied.

Measuring the Internal Velocity of Debris Flows Using Impact Pressure Detecting in the Flume Experiment

Measuring the internal velocity of debris flows is very important for debris flow dynamics research and designing debris flow control works. However, there is no appropriate method for measuring the internal velocity because of the destructive power of debris flow process. In this paper, we address this problem by using the relationship between velocity and kinetic pressure, as described by surface velocity and surface kinetic pressure data. Kinetic pressure is the difference of impact pressure and static pressure. The former is detected by force sensors installed in the flow direction at the sampling section. Observations show that static pressure can be computed using the formula for static water pressure by simply substituting water density for debris flow density. We describe the relationship between surface velocity and surface kinetic pressure using data from seven laboratory flume experiments. It is consistent with the relationship for single phase flow, which is the measurement principle of the Pitot tube.

Static and Dynamic Analyses of Long-Span Spatial Steel-Cable-Membrane Hybrid Structures

With the increment of the complexity of structural systems and the span of spatial structures, the interactions between parts of the structures, especially between some flexible substructures, become too complex to be analyzed clearly. In this paper, taking an actual gymnasium of a long-span spatial steel-cable-membrane hybrid structure as the calculation model, the static and dynamic analyses of the hybrid structures are performed by employing the global analysis of the whole hybrid structure and the substructural analysis of the truss arch substructure, the cable-membrane substructure, etc. In addition, the comparison of stresses and displacements of structural members in the global and substructural analyses is made. The numerical results show that serious errors exist in the substructural analysis of the hybrid structure, and the global analysis is necessary for the hybrid structure under the excitation of static loads and seismic loads.

Static-deformation based fault diagnosis for damping spring of large vibrating screen

Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.

Elastodynamic modeling and joint reaction prediction for 3-PRS PKM

To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used as a case study to illustrate the process of joint reaction analysis. The substructure synthesis method is applied to deriving an analytical elastodynamic model for the 3-PRS PKM device, in which the compliances of limbs and joints are considered. Each limb assembly is modeled as a spatial beam with non-uniform cross-section supported by lumped virtual springs at the centers of revolute and spherical joints. By introducing the deformation compatibility conditions between the limbs and the platform, the governing equations of motion of the system are obtained. After degenerating the governing equations into quasi-static equations, the effects of the gravity on system deflections and joint reactions are investigated with the purpose of providing useful information for the kinematic calibration and component strength calculations as well as structural optimizations of the 3-PRS PKM module. The simulation results indicate that the elastic deformation of the moving platform in the direction of gravity caused by gravity is quite large and cannot be ignored. Meanwhile, the distributions of joint reactions are axisymmetric and position-dependent. It is worthy to note that the proposed elastodynamic modeling method combines the benefits of accuracy of finite element method and concision of analytical method so that it can be used to predict the stiffness characteristics and joint reactions of a PKM throughout its entire workspace in a quick and accurate manner. Moreover, the present model can also be easily applied to evaluating the overall rigidity performance as well as statics of other PKMs with high efficiency after minor modifications.

Asymptotic analysis of mode Ⅰ propagating crack-tip field in a creeping material

Adopting an elastic-viscoplastic, the asymptotic problem of mode I propagat ing crack-tip field is investigated. Various asymptotic solutions resulting from the analysis of crack growing programs are presented. The analysis results show that the quasi-statically growing crack solutions are the special case of the dynamic propagating solutions. Therefore these two asymptotic solutions can be unified.

Effect of Static Magnetic Field on α-Amylase Activity and Enzymatic Reaction

The effect of magnetic field on a-amylase was studied. Under the experimental conditions, a-amylase solution was treated by 0.15 T, 0.30 T and 0.45 T static magnetic fields for a known period of time, then the activity, kinetic parameters, and the secondary conformation were investigated. The results showed that there was a considerable effect of the magnetic exposure on the α-amylase. The activity was increased by 27%, 34.1%, 37.8% compared with the control. It was also found that both kinetic parameters Km and Vm could be decreased due to the increasing magnetic field, Km decreased from 2.20×10^2 to 0.87×10^2, whereas Vm decreased from 2.0×10^3 g/min to 1.1 ×10^3 g/min. At the same time, there were some irregular changes in a-amylase secondary conformation.

Dynamic responses research of offshore wind turbine tripod foundation and upper structure

In order to obtain the performance of the offshore wind turbine tripod foundation, a tripod foundation model was built by ANSYS. The static analysis, modal analysis and the transient dynamic analysis were run. Different parameters such as displacement, velocity, acceleration, stress were obtained and by analyzing these data, it is reasonable to draw a conclusion that the tripod foundation has a good performance used on the offshore wind turbine.

冷轧基板SPHE静态再结晶行为研究

利用Gleeble-3500热力模拟试验机研究了冷轧基板SPHE钢的静态再结晶行为,通过对奥氏体再结晶行为的研究,得到试验钢发生静态再结晶时变形温度越高,发生静态再结晶越容易。试验钢在900、950和1 000℃变形过程中停留不同时间,再结晶分数出现了个别点下降,是试验检测误差所致;随着停留时间的增加,由于溶质原子和碳化物等第二相质点的析出,引起了再结晶速率降低。试验钢SPHE发生静态再结晶的激活能为239.87kJ/mol。

A forward-inverse dynamics modeling framework for human musculoskeletal multibody system

Multibody musculoskeletal modeling of human gait has been proved helpful in investigating the pathology of musculoskeletal disorders.However,conventional inverse dynamics methods rely on external force sensors and cannot capture the nonlinear muscle behaviors.Meanwhile,the forward dynamics approach is computationally demanding and only suited for relatively simple tasks.This study proposed an integrated simulation methodology to fulfill the requirements of estimating foot-ground reaction force,tendon elasticity,and muscle recruitment optimization.A hybrid motion capture system,which combines the marker-based infrared device and markerless tracking through deep convolutional neural networks,was developed to track lower limb movements.The foot-ground reaction forces were determined by a contact model for soft materials,and its parameters were estimated using a two-step optimization method.The muscle recruitment problem was first resolved via a static optimization algorithm,and the obtained muscle activations were used as initial values for further simulation.A torque tracking procedure was then performed by minimizing the errors of joint torques calculated by musculotendon equilibrium equations and inverse dynamics.The proposed approach was validated against the electromyography measurements of a healthy subject during gait.The simulation framework provides a robust way of predicting joint torques,musculotendon forces,and muscle activations,which can be beneficial for understanding the biomechanics of normal and pathological gait.