惯性力学与整体科学体系

古代人无法理解地球下面的人为什么不会掉下去，此困惑是由于以自己为参考系而产生的。今天的人们无法理解自由落体运动及天体的公转运动也是惯性运动，此困惑是由于以牛顿惯性为“参考系”而产生的。惯性的实质就是：物体通过某种运动状态来保持或主动改变某种运动状态来达到其内部的熵状态的一种属性。整体科学体系是研究自然整体的整体性质与功能、有序内部结构及其起源与演化过程的科学理论系统。

浅谈惯性力学

物体在受到外力(去掉外力性质的重力-引力及合外力不为零的情况下)的时候其内部到底发生了什么情况?这是区别物体是否是广义惯性运动状态的根本标准。这涉及到牛顿力学物体概念内涵的改变。如果把熵状态(熵空间)作为力学思维的出发点,许多纠缠不清的问题都好解决。

Exact Computation of Parallel Robot's Generalized Inertia Matrix

According to the definition of the new hypothetical states which have obvious physical significance and are termed as no-gravity static and accelerated states, a method for exact computation of the parallel robot＇s generalized inertia matrix is presented. Based on the matrix theory, the generalized inertia matrix of the parallel robot can be computed on the assumption that the robot is in these new hypothetical states respectively. The approach is demonstrated by the Delta robot as an example. Based on the principle of the virtual work, the inverse dynamics model of the robot is formulized after the kinematics analysis. Finally, a numerical example is given and the element distribution of the Delta robot＇s inertia matrix in the workspace is studied. The method has computationa＇, advantage of numerical accuracy for the Delta robot and can be parallelized easily.

Equivalent bending stiffness of simply supported preflex beam bridge with variable cross-section

In order to understand mechanical characters and find out a calculating method for preflex beams used in particular bridge engineering projects, two types of simply supported preflex beams with variable crosssection, preflex beam with alterative web depth and preflex beam with aherative steel flange thickness, are dis- cussed on how to achieve the equivalent moment of inertia and Young＇ s modulus. Additionally, methods of cal- culating the equivalent bending stiffness and post-cracking deflection are proposed. Results of the experiments on 6 beams agree well with the theoretical analysis, which proves the correctness of the proposed formulas.

基于反演法的智能汽车连续换道轨迹控制技术

汽车在连续换道中容易出现轨迹偏离和失稳,需要进行智能汽车连续换道轨迹控制设计,提高汽车控制稳定性,提出一种基于反演法的智能汽车连续换道轨迹控制方法。在常规滑膜面上建立汽车连续换道轨迹运动模型,结合汽车连续换道的惯性力学特征和车体偏移特征进行位姿调整和参量镇定性处理,采用实时反馈修正方法进行汽车连续换道轨迹渐进修正,避免轨迹偏离修正过程中的车身失稳,采用反演积分法进行稳态调节控制,提高汽车连续换道过程中稳态调节性能和车身平衡性。仿真结果表明,采用该方法进行智能汽车连续换道轨迹控制能有效避免轨迹偏离,车身的稳定性和轨迹跟踪性能较好,提高了汽车换道控制品质。

Deployment dynamics and topology optimization of a spinning inflatable structure

Inflatable space structures may undergo the vibration of a long duration because of their features of dynamic deployment,high flexibility,and low-frequency modes.In this paper,a topology optimization methodology is proposed to reduce the vibration of a spinning inflatable structure.As the first step,a variable-length shell element is developed in the framework of arbitrary Lagrange-Euler(ALE)and absolute nodal coordinate formulation(ANCF)to accurately model the deployment dynamics of the inflatable structure.With the help of two additional material coordinates,the shell element of ALE-ANCF has the ability to describe the large deformation,large overall motion,and variable length of an inflatable structure.The nonlinear elastic forces and additional inertial forces induced by the variable length are analytically derived.In the second step,a topology optimization procedure is presented for the dynamic response of an inflatable structure through the integration of the equivalent static loads(ESL)method and the density method.The ESL sets of the variable-length inflatable structure are defined to simplify the dynamic topology optimization into a static one,while the density-based topology optimization method is used to describe the topology of the inflatable structure made of two materials and solve the static optimization problem.In order to obtain more robust optimization results,sensitivity analysis,density filter,and projection techniques are also utilized.Afterwards,a benchmark example is presented to validate the ALE-ANCF modeling scheme.The deployment dynamics and corresponding topology optimization of a spinning inflatable structure are studied to show the effectiveness of the proposed topology optimization methodology.

Numerical Study of U-beam Inertial Separator

A detailed parametric study is conducted on three-dimensional gas-solid multiphase flow characteristics in inertial separators via numerical simulation. The carrier phase is treated in the Eulerian frame, the particles are tracked in the Lagrangian frame, and particle-wall collision and particle-particle collision are considered. The inertial separators are made out of U-beam tube, arranged staggered .The separator has good performance for large particles and its compact structures make it easy to manufacture and install. The simulation is carried out in different inflow rate and provide the pressure losses in the separators, velocity field of gas phase, the trajectories of particles and the separation efficiency of separators. The result from this study not only shows the multiphase flow-dynamic characteristics of the separators, but also gives the relationship among the efficiency, structure and pressure losses of the separator. The comparison between the numerical simulation result and experimental data demonstrate the reliability of the numerical simulation.

GLOBAL DYNAMICS OF DISSIPATIVE GENERALIZED KORTEWEG-DE VRIES EQUATIONS

This work deals with the dissipative generalized Korteweg-de Vries (gKdV) equations of the formu t + u 2u x + u xxx-bu xx+ ru = f, t≥0, u(0,x) = u 0(x)∈V = H 2 2π,with periodic boundary conditions. It is proved that there exists an inertial manifold for the semiflow generated by this equation in space V. Since such a manifold is finite dimensional, positively invariant, and exponentially attracting of all the solution trajectories, the long-time dynamics of the dissipative gKdV equations are determined by a finite number of modes without the soliton phenomena.

Theoretical and simulation research of hydrodynamic instabilities in inertial-confinement fusion implosions

Inertial fusion energy （IFE） has been considered a promising, nearly inexhaustible source of sustainable carbon-free power for the world＇s energy future. It has long been recognized that the control of hydrodynamic instabilities is of critical importance for ignition and high-gain in the inertial-confinement fusion （ICF） hot-spot ignition scheme. In this mini-review, we summarize the progress of theoretical and simulation research of hydrodynamic instabilities in the ICF central hot-spot implosion in our group over the past decade. In order to obtain sufficient understanding of the growth of hydrodynamic instabilities in ICF, we first decompose the problem into different stages according to the implosion physics processes. The decomposed essential physics pro- cesses that are associated with ICF implosions, such as Rayleigh-Taylor instability （RTI）, Richtmyer-Meshkov instability （RMI）, Kelvin-Helmholtz instability （KHI）, convergent geometry effects, as well as perturbation feed-through are reviewed. Analyti- cal models in planar, cylindrical, and spherical geometries have been established to study different physical aspects, including density-gradient, interface-coupling, geometry, and convergent effects. The influence of ablation in the presence of preheating on the RTI has been extensively studied by numerical simulations. The KHI considering the ablation effect has been discussed in detail for the first time. A series of single-mode ablative RTI experiments has been performed on the Shenguang-II laser facility. The theoretical and simulation research provides us the physical insights of linear and weakly nonlinear growths, and nonlinear evolutions of the hydrodynamic instabilities in ICF implosions, which has directly supported the research of ICF ignition target design. The ICF hot-spot ignition implosion design that uses several controlling features, based on our current understanding of hydrodynamic instabilities, to address shell implosion stability, has been briefly described, several of which are novel.

Numerical Simulation of 2-D Radiation-Drive Ignition Implosion Process

A Lagrangian compatible radiation hydrodynamic algorithm and the nuclear dynamics computing module are developed and implemented in the LARED Integration code, which is a radiation hydrodynamic code based on the 2-D cylindrical coordinates for the numerical simulation of the indirect-drive Inertial Confined Fusion. A number of 1-D and 2-D ignition implosion numerical simulations by using the improved LARED Integration code (ILARED) are presented which show that the 1-D numerical results are consistent with those computed by the 1-D radiation hydrodynamic code RDMG, while the simulation results of the 2-D low-mode radiative asymmetry and hydrodynamic instability growth,according to the physical analysis and anticipation, are satisfactory. The capsules driven by the sources from SGII experiments are also simulated by ILARED, and the fuel shapes agree well with the experimental results. The numerical simulations demonstrate that ILARED can be used in the simulation of the 1-D and 2-D ignition capsule implosion using the multi-group diffusion model for radiation.