EFFECTS OF MOIST PROCESS ON SUBTROPICAL FLOW PATTERNS AND MULTIPLE EQUILIBRIUM STATES

A low-order general circulation moisture model is presented, and some experiments with it are described. The model is based on the quasi-geostrophic motion in the β-plane of two layers with landsea distribution. As proposed by Lorenz, the moisture variable in the model is the total dewpoint. Modeled processes consist of evaporation, precipitation, and the effects of clouds and water vapor on radiation.Results of the experiments with the model show that the moisture process enhances subtropical highs significantly and the meridional development of flow. It can also reproduce the hi-equilibrium states in certain parametric combinations, which is similar to the observational fact about the "Eastern pattern" and the "Western pattern" circulations in the subtropical areas during the summer half year.     

EFFECTS OF MOIST PROCESSES ON LOW-FREQUENCY OSCILLATIONS OF GENERAL CIRCULATION OVER NORTHERN HEMISPHERE DURING SUMMER TIME

In this paper the Lorenz's moist low-order spectral model~([1]) is further improved by introducinga parameterization for cumulus convection into it. Numerical experiments by this improved model mani-fest quasi-three week oscillations both in the location of the simulated subtropical high at upper tropo-sphere along cast-west direction and in the simulated vertical velocities and precipitation over South Asia,which is similar to those in the real atmosphere. The results of the experiments and the computationsof parameters of energetics show that introducing moist processes is a necessary condition for stimulat-ing and maintaining the low-frequency oscillations, and that moist convection can also obviously shortenoscillation periods, which is generally in agreement with the conclusions in another paper~([2]) of theauthors.     

热带气旋逆时针打转异常路径的可能原因

本文用一个带有环境加热项和耗散项的正压准地转模式,实施了6组时间积分大于7天的数值试验。模式大气中,清楚地显示出热带气旋在移动过程中逆时针打转的现象。数值地研究了这种异常路径对计算区域的大小、热源扰动、初值扰动和迭代精度扰动的稳定性问题。认为该异常路径是模式大气中一种比较稳定的运动形态,最后分析了逆时针打转异常路径的可能原因。     

基于动压约束的高超声速飞行器机动突防制导策略

针对高超声速飞行器临近空间机动突防问题,提出一种基于最低动压约束的高超声速飞行器临近空间大空域机动策略.对基于模型预测静态规划(MPSP)制导方法进行改进,末端时刻输出量考虑末端时刻时间偏差影响,性能指标函数考虑控制量输入约束影响,推导得到带多个航路点约束的扩展MPSP制导方法.根据战场态势对航路点处的动压进行约束,调...     

气垫车辆土壤参数估值算法

针对气垫车辆具有附加的垂向力控制自由度的特点,提出了基于g函数和扩展卡尔曼滤波器（EKF）联合算法的土壤参数估值方案.g函数通过解耦土壤参数解决了多解问题,EKF通过减小测量不确定度提高了估值准确性.通过不同噪声水平下算法准确性和大噪声重复实验下算法稳定性的实验表明：g-EKF联合算法在各种噪声水平下具有应用鲁棒性,特别是在大噪声工况下,其估值准确性、精确性和稳定性具有明显优势.     

基于主动转向的车辆路径跟随广义预测控制

为了增强车辆在外界干扰存下的路径跟随性能,提出了一种基于广义预测控制(GPC)的主动转向控制器来保证车辆对于路径的跟踪能力.采用受控自回归积分滑动平均模型(CARIMA)作为预测模型,通过带遗忘因子的最小二乘法辨识方法获得CARIMA模型参数,避免了由于车辆非线性造成的参数化建模不准确、繁琐问题.使用车辆路径侧向跟踪误差作为控制器输入,方向盘附加转角作为输出,与驾驶员方向盘转角进行综合,获得车辆方向盘最终转角.在Simulink-CarSim联合仿真环境下,验证了所设计控制器在双移线工况有强侧向风干扰时车辆对路径的跟随性能.     

NONLINEAR MECHANISM OF ABRUPT CHANGE OF ATMOSPHERIC CIRCULATION DURING JUNE AND OCTOBER

By the low-order spectral model, the abrupt change of the circulation in the barotropic atmosphere is studied. In certain parametric combinations, along with the gradual change of the external thermal forcing, the quasi-cusp pattern abrupt changes of both the spectral coefficients and the locations of west jet stream are stimulated, which are similar to the rapid northward jumping and suddenly establishing of the "South-Branch" jet stream during June and October respectively. Depending on the changes of the parametric combinations, the motional form of the abrupt change can be substituted by that of the gradual change of one stable equilibrium, or by that of the branching phenomena of the multiple equilibria. The abrupt change mechanism of the atmospheric circulation is a nonlinear mechanism which contains the thermal forcing, dissipation, and thermal and dynamic effects.     

我国国有资产管理体制改革研究综述

2 0 0 4年 2月 2 4～ 2 5日 ,全国国有资产监督管理工作会议在北京召开。这是一次具有重大意义的会议 ,会议强调 ,要以邓小平理论和“三个代表”重要思想为指导 ,认真贯彻十六大和十六届三中全会精神 ,进一步统一思想 ,明确责任 ,扎实推进国有资产管理体制改革和国有企业改革 ,开创国有资产监督管理工作和国有企业改革发展新局面。深化国有资产管理体制改革极具探索性和挑战性 ,没有现成经验可以借鉴。当前 ,在国有资产管理体制改革和国有企业改革中存在的一些问题 ,包括一些认识上的偏差。本文将阐明对这些问题的理解 ,并说明在完善国有资产监督管理体制和深化国企改革实践和理论中需要继续探索的有关问题。     

BIFURCATIONS FROM STATIONARY TO PERIODIC STATES AND TWO KINDS OF LOW-FREQUENCY OSCILLATIONS OF SUBTROPICAL FLOW PATTERNS

A parameterization for convective heating is introduced into the diabatic term of a two-layer, low-or-der spectral model for estimating the effects of moist convection on bifurcations fro mstationary to period-ic states of flow patterns. In certain parameter combinations, thermal forcing with the parameterizationcan generate bifurcations from stationary to periodic states. However, the forcing without it does not ex-cite such bifurcations. The time scales corresponding to their periodic states are about two-three weeks.In other parameter combinations, the thermal forcing either with or without the convective heating cangenerate the bifurcations from stationary to periodic states; but the effects of convective heating shortenthe time scales and accelerate the amplifications of the excited periodic oscillations. The instabilities of the stationary states, which represent a uniform distribution of the subtropicalflow pattern at the upper layer of the model atmosphere, may form two kinds of low-frequency os