基于Simulink和FlightGear软件的机载惯性测量单元仿真

包含动力学和运动学特性的机载IMU数据对于飞行对准等惯性系统算法研究具有重要意义。基于人在回路仿真的思想,设计了一种可包含完整飞机模型,不需要设计特定的自动驾驶仪,来实现任意机动下机载惯性测量单元仿真的方案。给出了惯性测量单元仿真模型,设计了基于Simulink、AeroSim模块集及FlightGear模拟飞行软件的新方案,实现了一个机载惯性测量单元的仿真模型,该模型采用飞行摇杆,由人实现对飞机的控制和机动飞行。仿真结果表明,采用该仿真方案,避免了复杂的自动驾驶仪设计,可以得到机动飞行条件下的机载惯性测量单元仿真数据和导航参数基准数据,方案切实可行。     

基于虚拟节点连接的道路网络模型

利用传统的基于节点连接的道路网络模型来表达真实世界中的道路网络,其存在的缺陷越来越突出,大大降低了导航系统的鲁棒性。为了消除这些缺陷,提出一个新的道路网络模型,即基于虚拟节点连接的道路网络模型;其虚拟节点是汇交路段的各个端点所围成的区域,具有真实道路路口的形状。与传统模型相比,该模型更能表达真实世界道路网络中的交通流,所以它能更好地满足地图匹配理论要求。另外,该模型能很好地表达真实道路路口参数,所以它在交通规划、交通管理和交通流模拟中都有着十分广阔的应用前景。     

Virtual experimentation through 3D full-loop simulation of a circulating fluidized bed

Eulerian granular multiphase model with a drag coefficient correction based on the energy-minimization multi-scale （EMMS） model was used to simulate a semi-industry scale circulating fluidized bed （CFB）. Three-dimensional （3D）, time-dependent simulation of a full-loop CFB revealed that the axial profiles of cross-sectionally averaged solid volume fraction, and the radial profiles of solid axial velocity and solid volume fraction were in reasonable agreement with experimental data. Based on this agreement, database derived from experiments not yet accomplished was replenished with such simulations, and fluid regime diagrams and pressure balance around the CFB loop were derived accordingly. This work presents an integrated viewpoint on CFB and unfolds a fresh paradigm for CFB modeling, which can be expected to help resolve certain issues long in dispute but bard for experiments.     

Assessing mixing characteristics of particle-mixing and granulation devices

The mixing of particulates such as powders is an important process in many industries including pharmaceuticals, plastics, household products （such as detergents） and food processing. The quality of products depends on the degree of mixing of their constituent materials which in turn depends on both geometric design and operating conditions. Unfortunately, due to lack of understanding of the interaction between mixer geometry and the granular material, limited progress has been made in optimizing mixer design. The discrete element method （DEM） is a computational technique that allows particle systems to be simulated and mixing to be predicted. Simulation is an effective way of acquiring information on the performance of different mixers that is difficult and/or expensive to obtain using traditional experimental approaches. Here we demonstrate how DEM can be used to unravel flow dynamics and assess mixing in several different types of devices. These devices used for mixing and/or granulation of particulates, are classified broadly as gravity controlled, bladed and high shear. We also explore the role of particle shape in mixing performance and use DEM to test whether Froude number scaling is suitable for predicting scale performance of rotating mixers.     

Pattern formation in particle systems driven by color field

The structural evolution of systems with two kinds of particles driven in opposite directions, i.e., driven by a color field, is investigated by molecular dynamics simulations. Gaussian thermostat, a common treatment to restrict the thermal velocity of the particles in the systems, has been used so as to account for the dissipation of heat and allow the system to reach a steady state. It has been found that with the increase of the strength of driving force （F）, the system undergoes an obvious structural transition from an initially random mixing state to a state characterized by separate lanes and in each lane only one kind of particles exists. The analysis shows that the reason for the formation of lane structure is not only the increase of F but also the variation of particle friction coefficient. While using Gaussian thermostat the particle friction coefficient becomes a function of F. Increasing F leads to high particle friction coefficient and inevitably results in lane formation for strong enough driving force. When lifting the effect of F on friction coefficient and choosing a constant friction coefficient, our results show that for a given F there always exists a critical value of friction coefficient higher than which the system will develop into lane structure.     

DEM simulations of die filling during pharmaceutical tabletting

The flow behaviour of powders from a stationary shoe into a moving die, which mimics the die filling process in a rotary tablet press, was analysed using a discrete element method （DEM）, in which 2D irregular shaped particles were considered. The influence of the particle shape, size and size distribution, the number of particles used in the simulation, the initial height of powder bed in the shoe, and the filling speed on the average mass flow rate and the critical filling speed （the highest speed at which the die can be completely filled） were explored. It has been found that a maximum flow rate is obtained at the critical filling speed for all systems investigated and poly-disperse systems have higher mass flow rates and higher critical filling speeds than mono-disperse systems. In addition, the powder with particles which can tessellate generally has a lower filling rate and a lower critical titling speed.     

平带驱动系统的振动分析研究进展

综述汽车发动机中带张紧装置的平带驱动系统振动分析的研究进展,在转动振动的力学模型和相应数学模型基础上,总结了用数值方法,复模态分析方法和增量谐波平衡法进行线性振动和非线性振动分析以及打滑预测的结果,在转动－横向耦合振动的力学模型和数学模型基础上,总结了用数值方法,Holzer法,模态分析法和直接多尺度法进行线性振动和非线性振动分析的结果,最后提出需要深入研究的若干问题。     

基于卡尔曼滤波算法的汽车运动参数测试方法研究

提出了一种采用多维组合惯性测量元件进行汽车运动参数测试的方法,并利用卡尔曼滤波算法提高了测试系统的精度。仿真结果表明：卡尔曼滤波算法对汽车姿态、速度等的解算具有较好的效果。     

自适应卡尔曼滤波方法及其在容错组合导航系统的系统级故障检测中的应用

提出了采用自适应加权和卡尔曼滤波相结合的自适应滤波方法进行组合导航系统极故障检测的新思路。该方法不仅可以判断出故障是否出现,而且可以对故障量的值进行跟踪估计,在估计的同时可以判断故障值出现在哪一个量测通道中。SINS／GPS组合导航系统故障检测和隔离的系统仿真结果验证了本算法的有效性。     

某型工程车系统可靠性分析

本应用失效树分析法,以某型工程车进行了可靠性分析,建立了该系统的失效树,在此基础上用最小割集法和系统失效树的可靠性仿真法计算了该系统的可靠性参数,并对一些结果进行了比较。