Application of Disaggregated Logit Modeling with Stated Preference Method in Park and Ride Behavior for Non-local Private Car Travelers in Big Events

During big events, non-local private car travelers can be divided into two types which were returning in one day and in several days. It was demonstrated that those two kinds of travelers have distinct behavior on park and ride （P＆R）, due to their different travel demand and behavior attributes. In this paper focusing on the travelers returning in several days, the travel attributes and requirements for P＆R were analyzed with stated preference survey. A P＆R choice behavior disaggregated logit model was established and calibrated based on random utility theory. The model concludes three variables, which were travel time, parking fee and comprehensive attractiveness index for suburban satellite towns comparing to urban district. The results revealed that for travelers returning in several days the primary key point is increasing the attractiveness of suburban satellite towns.     

Analysis of Policy Factors in the Stock Market

One model of stochastic time series - Markov chain was presented in this paper. We study and discuss the application of this model. Some results that the policy factor make to stock price were offered when this model is applied to analyze the index of Shanghai stock market quantitatively.     

Research on improved integrated FDD/FTC with effectiveness factors

This paper investigates the integrated fault detection and diagnosis(FDD) with fault tolerant control(FTC) method of the control system with recoverable faults.Firstly,a quasi-linear parameter-varying(QLPV) model is set up,in which effectiveness factors are modeled as time-varying parameters to quantify actuators and sensors faults.Based on the certainty equivalency principle,replacing the real time states in the nonlinear term of the QLPV model with the estimated states,the parameters and states can be estimated by a two-stage Kalman filtering algorithm.Then,a polynomial eigenstructure assignment(PEA) controller with time-varying parameters and states is designed to guarantee the performance of the system with recoverable faults.Finally,mathematical simulation is performed to validate the solution in a satellite closed-loop attitude control system,and simulation results show that the solution is fast and effective for on-orbit real-time computation.     

在线订餐生产配送联合调度模型及算法

The delays of online meal ordering delivery are currently serious. How to coordinate the production and distribution to minimize arrival time has become an urgent problem for online meal ordering during the peak period. Considering the fact that the order information are unknown in advance, a parallel machine production and multi-trip vehicle distribution joint optimization model was established to minimize the makespan of total orders. Besides, a three phase heuristic algorithm was proposed. Through a series of experiments where the orders were generated based on Poisson distribution (),the results were compared with those of the traditional algorithm. Several enlightening findings are discovered: when the order arrival rate, the makespan of total orders of the three phase heuristic algorithm is shorter. Meanwhile with the growth of order arrival rate, the improvement amplitude increases gradually. The model and algorithms proposed are conducive to generating efficiently production and distribution joint scheduling solution during the peak period.     

Single channel signal component separation using Bayesian estimation

A Bayesian estimation method to separate multicomponent signals with single channel observation is presented in this paper. By using the basis function projection, the component separation becomes a problem of limited parameter estimation. Then, a Bayesian model for estimating parameters is set up. The reversible jump MCMC （Monte Carlo Markov Chain） algorithmis adopted to perform the Bayesian computation. The method can jointly estimate the parameters of each component and the component number. Simulation results demonstrate that the method has low SNR threshold and better performance.     

Dual loop feedback pre-distortion in satellite communication

Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.     

Identification of linear continuous-time system using wavelet modulating filters

An approach to identification of linear continuous-time system is studied with modulating functions. Based on wavelet analysis theory, the multi-resolution modulating functions are designed, and the corresponding filters have been analyzed. Using linear modulating filters, we can obtain an identification model that is parameterized directly in continuous-time model parameters. By applying the results from discrete-time model identification to the obtained identification model, a continuous-time estimation method is developed. Considering the accuracy of parameter estimates, an instrumental variable (Ⅳ) method is proposed, and the design of modulating integral filter is discussed. The relationship between the accuracy of identification and the parameter of modulating filter is investigated, and some points about designing Gaussian wavelet modulating function are outlined. Finally, a simulation study is also included to verify the theoretical results.     

一种新型UUV半实物仿真系统设计与实现

针对UUV导航与控制系统高精度仿真的需要,设计了一种支持捷联惯导、多普勒测速仪、深度传感器和GPS接收机接入的半实物仿真系统,解决了GPS卫星导航信号仿真、多普勒测速仪水声回波模拟和UUV深浅水航行深度模拟问题,进行了导航与控制系统的半实物仿真试验,分别测试了GPS导航仿真子系统、多普勒测速仿真子系统和深度模拟子系统。试验结果表明,该仿真系统满足了仿真实时性和计算精度的要求,对于UUV研制具有重要的应用价值。

Abstract：

To satisfy the requirement of high accuracy simulation of complicated navigation and control system of unmanned underwater vehicle, a new plan of simulation system was proposed, which afforded the interface environment for SINS, Doppler velocity instrument, depth sensor and GPS receiver. The GPS satellite navigation signal simulation, the acoustic echo of Doppler velocity instrument and the sailing depth simulation were solved. The simulation experimentation combining hardware was processed, and the GPS simulation subsystem, the Doppler velocity simulation subsystem and the sailing depth simulation subsystem were all tested. The results show that the simulation system meets the real-time and accuracy requirements, and the system has important application value for UUV development.     

CALENDAR EFFECTS IN MONTHLY TIME SERIES MODELS

1. Introduction In the 1960s the attempts to describe an economy by large macroeconometric models were under heavy critique. These models with hundreds of macroeconomic variables and equations, could track the data very well over the historical period where the model parameters are estimated but often performed poorly when are used for out-of-sample forecasting. Part of the disillusionment with these efforts was the discovery that univariate time series models with low order autoregressive and…     

Adaptive fault-tolerant controller design for airbreathing hypersonic vehicle with input saturation

The problem of fault-tolerant control is discussed for the longitudinal model of an airbreathing hypersonic vehicle(AHV) with actuator faults and external disturbances.Firstly,a fault-tolerant control strategy is presented for the longitudinal model of an AHV,which guarantees that velocity and altitude track their reference trajectories at an exponential convergence rate.However,this method needs to know the minimum value of the actuator efficiency factor and the upper bound of the external disturbances,which makes it not easy to implement.Then an improved adaptive fault-tolerant control scheme is proposed,where two adaptive laws are employed to estimate the upper bound of the external disturbances and the minimum value of the actuator efficiency factor,respectively.Secondly,the problem of designing a control scheme with control constraints is further considered,and a new adaptive fault-tolerant control strategy with input saturation is designed to guarantee that velocity and altitude track their reference trajectories.Finally,simulation results are given to show the effectiveness of the proposed methods.     

基于遗传算法的卫星攻击轨道优化方法

在空间攻防与卫星对抗中,当目标卫星周围有若干小卫星以编队形式对其绕飞时,为使拦截卫星成功击中目标卫星,并且避开编队小卫星的防御区,必须对拦截卫星攻击轨道进行规划。寻找到一条既能满足安全性、快速性,又能节省燃料的最优路径。而利用经典数学规划方法,如序列二次规划方法,虽能寻找到最优路径,但并不适应于解决空间对抗中复杂攻防环境模型下的轨道规划问题。为此本文提出基于遗传算法的拦截卫星攻击轨道寻优方法。建立目标卫星编队小卫星的动态防御模型作为环境模型,采用可变长度实数编码方式,根据攻击轨道安全性、快速性、燃料消耗最少等要求建立综合适应度函数,并对遗传算子及置换运算方法进行设计。通过仿真验证,本文提出的轨道优化方法能够寻求到最优攻击路径,并且算法收敛速度较快。     

主星带伴随微小卫星编队SAR系统的模糊性分析

针对主星带伴随微小卫星编队SAR系统的模糊性问题,利用主星带伴随微小卫星编队SAR系统的空间几何关系,提出了一种该系统模糊度的工程计算方法。首先建立了主星与微小卫星构成的双站合成孔径雷达系统模型,然后结合微小卫星天线孔径小的特点,建立了距离模糊度和方位模糊度的计算表达式。仿真结果发现,主星到伴随微小卫星的距离对距离模糊度的影响较大,而对方位模糊度的影响较小,方位模糊度受微小卫星天线孔径大小的影响较大。     

多任务微小卫星姿态仿真研究

为了实现在整星制约条件下,以经济而可靠的手段满足三轴稳定多任务微小卫星(MTMS)姿态控制系统的功能和性能要求,分析了MTMS的运行任务,提出了基于多任务要求的工作模式划分,并对多任务过程的姿态确定和姿态控制系统进行综合分析和设计,建立数学模型。通过仿真验证,可实现多任务微小卫星的复杂任务设计要求。     

基于PSO-BP神经网络的广播星历轨道误差预测模型

在卫星导航数据处理实践中,发现广播星历轨道误差中客观存在不确定性的规律现象,针对这种不能用确定数学模型表示的误差信息,建立基于粒子群优化反向传播(back propagation,BP)神经网络的轨道误差预测模型。通过粒子群算法对BP神经网络的初始权值和阈值进行全局寻优,利用广播星历解算出的卫星空间位置和速度,并结合时间信息和摄动改正数对神经网络进行训练和测试。结果表明该模型对广播星历轨道误差具有较好的拟合能力和预测效果,用该模型对卫星位置解算提供误差补偿,可有效提高卫星定轨精度,降低系统级误差。     

微小卫星编队系统的干涉SAR 空间基线稳定性分析

基线在星载干涉SAR的系统设计和数据处理中起着非常重要的作用,对于微小卫星编队系统来说稳定性问题是干涉SAR空间基线的一个重要问题.首先建立了空间基线的几何模型,定义了垂直基线、有效基线和水平基线.根据微小卫星编队飞行的特点,建立了空间基线的动态模型.基于这个模型,提出了一种空间基线稳定度的计算方法.最后,比较了不同编队构形和不同卫星数目两种憎爱分明形下空间基线稳定度.仿真结果表明空间基线稳定度的计算方法是有效的.     

基于模型概率的多模型融合定轨建模及仿真

针对实际定轨系统中存在的不确定性和非线性性,提出了一种基于模型概率的多模型融合定轨方法.通过多个线性模型的组合来逼近卫星定轨复杂非线性时变过程,将卫星状态的最优估计与多模型融合方法相结合,利用残差的大小来设计性能指标函数,给出了两种模型概率的表示形式,并建立了多模型融合估计相应的算法.仿真结果表明,与单一模型定轨方法相比,该方法不仅能大大提高卫星定轨精度和可靠性,而且还可以最终辨识和估计模型参数的真值,且对外界环境发生的变化有很强的自适应能力.     

基于双星定位系统的近地卫星定轨精度仿真

通过对测距误差特性的统计分析,建立了用于近地卫星精密定轨的距离和观测数据仿真方法,在此基础上构建了基于卫星动力学方程的精密定轨模型,设计了一种基于数值融合法的精密定轨改进算法和测距系统误差参数估计算法,并进行了六类仿真实验。仿真计算结果表明,基于一天的距离和观测数据仿真计算得到的近地卫星定轨精度可以达到15.98米,与利用其他精密定轨软件系统在相同仿真条件下得到的近地卫星定轨精度基本相当,但该算法避免求解状态转移矩阵,具有计算速度快,稳健性好等特点。     

海基导弹初始误差分离建模与参数估计

影响海基导弹落点偏差的因素主要是制导工具误差和初始参数误差。首先分析了海基导弹初始误差的来源,包括三项定位误差、三项定向误差以及三项艇速误差。然后详细推导了初始误差对弹道遥测、外差数据的影响,建立了海基导弹初始误差分离的线性模型,结果表明初始误差与工具误差可以实现线性分离。最后根据六自由度弹道仿真程序仿真的遥测数据和外测数据对模型进行了验证,计算结果证实了模型和算法的正确性与可行性。     

微小卫星动量轮非线性模糊控制器的设计

动量轮是所有三轴稳定卫星姿态控制的主要和关键部件。由于微小卫星本身的转动惯量很小，微弱的非控制力矩都有可能导致整个卫星失控，因此对其动量轮控制器提出了无超调、超短响应时间、零稳态误差的理想设计要求，传统的PI控制器无法同时满足这些要求。提出了一种基于非线性模糊控制理论的模糊控制器，并给出了一个具体的设计实例，其仿真结果表明：这种控制器可以同时达到零超调、超小稳态误差(0．004％)、超短响应时间(小于1．5s)等设计要求，十分逼近动量轮的理想设计要求。     

基于不确定链路参数的卫星网络路由算法

对于卫星链路参数在复杂空间环境中存在不确定性的问题,研究了一种基于不确定链路参数的卫星网络路由算法。首先,采用三角模糊数描述链路参数的不确定性;在此基础上,建立卫星网络多约束路由模型;然后,设计保证路径有效性的遗传操作,通过遗传算法对路由模型进行求解;最后,通过仿真分析表明,该算法可以在复杂环境中实现高效路由,在平均时延、时延抖动和丢包率等方面有较好的效果。