检索结果-内蒙古大学图书馆

VERTICAL MOTION DIAGNOSTICS RELATED TO Q-VECTORS, AND THE REORGANIZATION OF A COLD FRONTAL SYSTEM

METEOROLOGY AND ATMOSPHERIC PHYSICS 1988年第2期39卷 65-73页

作者： TAPP, RG 1. Bureau of Meteorology Research Centre Gr-O Box 1289K 3001 Melbourne Australia

Estimates of vertical motion obtained by explicit solution of the quasi-geostrophic omega equation expressed in terms of Q-vectors (Hoskins et al., 1978) were compared with qualitative estimates based on the divergence of Q-vectors. The horizontal distributions of each were broadly similar, but differed in their detail. At any level, the relative magnitudes of centres of vertical motion varied between the parameters. The precise locations of the main centres also differed. Greater differences existed in the vertical distributions of the parameters. The divergence ofQ andF _Q of Hoskins et al. (1978) both reached maximum values in upper levels, whereas peak values of ω occurred in middle levels. A vertical distribution similar to ω was achieved ifF _Q was divided by a stability parameter. The diagnosed vertical velocities appeared consistent with the restructuring of a summertime cold front as it crossed waters south of Australia.

关键词： Diagnosis divergence Reorganisation Explicit Solution Divergence Divergence vertical motion cold front maximum value divergence Vertical distribution distributed parameter

来源：评论

学校读者我要写书评

暂无评论

From conservation laws to wave propagation and back -dynamics and control in combined heat/electricity generation

引用

IFAC-PapersOnLine 2015年第11 11期48卷 402-407页

作者： Râsvan, Vladimir Department of Automatic Control University of Craiova 13 A.I.Cuza str. CraiovaRO-200585 Romania

Starting from some pioneering papers in distributed parameter control systems for steam turbines and their auxiliaries, a bilinear model for steam turbines with steam extraction and “long” steam pipes was elaborated and the feedback control synthesis has been performed using a suitable control Liapunov functional of quadratic type, both for distributed parameters systems and their lumped parameter approximation. The synthesized control ensures global stabilization of the steady state solution. It has been observed much later that the linearized steam wave propagation equations underlying the model were in fact a simplified linearized version of the conservation laws of the isentropic flow. Following this remark and bearing in mind the recent advances in the control of the systems described by conservation laws, the model of the combined heat electricity generation is re-written as a system which is linear in control; consequently the feedback stabilization also requires re-examination. © 2015

关键词： distributed parameter control systems Control system synthesis Feedback Linearization Physical properties Stabilization Steam Steam turbines Wave propagation Conservation law distributed parameter Electricity generation Feedback stabilization Liapunov functionals Lumped parameter approximation Steady state solution Wave propagation equations

来源：评论

学校读者我要写书评

暂无评论

Structure of the earth's magnetosheath at small fluctuations in the interplanetary magnetic field direction

引用

COSMIC RESEARCH 2011年第4期49卷 281-291页

作者： Chugunova, O. M. Pilipenko, V. A. Zastenker, G. N. Shevyrev, N. N. Russian Acad Sci Space Res Inst Moscow 117810 Russia Russian Acad Sci Schmidt Joint Inst Phys Earth Moscow 123810 Russia

Spatial structure of the magnetosheath of the Earth was studied under the conditions when no sharp (more than 40A degrees during 5 min) changes in the interplanetary magnetic field direction were observed. On the basis of 24 flights of the Interball-1 satellite through the magnetosheath, it is found that three regions differing from each other by parameters of the field and plasma can be observed in the magnetosheath under the above-indicated conditions. These regions also differ from the solar wind region before front of the Earth's magnetospheric bow shock. Empirical distributions of parameters were studied in each region. Taking into account the influence of the interplanetary magnetic field direction on the processes in the magnetosheath, the cases of quasi-perpendicular and quasi-parallel shock waves were considered separately. The study showed that the distribution of parameters in the selected regions (in the solar wind before front of the bow shock, in the magnetosheath behind the bow shock (post-shock), in the region of the magnetosheath with minimal fluctuations in the field, and in the inner magnetosheath) differ from each other at any interplanetary magnetic field direction.

关键词： INTERPLANETARY MAGNETIC FIELDS solar wind magnetosheath field direction distributed parameter

来源：评论

学校读者我要写书评

暂无评论

Controller design of a distributed slewing flexible structure - A frequency domain approach

引用

JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME 1997年第4期119卷 809-814页

作者： Yang, SM Jeng, JA Liu, YC Natl Cheng Kung Univ Inst Aeronaut & Astronaut Tainan 70101 Taiwan Kaohsiung Polyteech Inst Dept Engn Mech Kaohsiung Taiwan

The vibration control of a slewing flexible structure by collocated and noncollocated feedback is presented in this paper. A stability criterion derived from the root locus method in frequency domain is applied to predict the closed-loop system stability of the distributed parameter model whose analytical transfer functions are formulated It is shown that the control law design requires neither distributed state sensing/estimation nor functional feedback gain;moreover, the spillover problem associated with discrete parameter model can be prevented. Implementation of the noncollocated feedback in a slewing beam experiment validates that the control law is effective in pointing accuracy while suppressing the tip vibration.

关键词： POINTING ACCURACY Distribute Flexible structures controller design Stability criteria distributed parameter root-locus technique vibration control TRANSFER FUNCTIONS control law

来源：评论

学校读者我要写书评

暂无评论

Conformational transitions of DNA induced by changing water content of the sample: A theoretical study

引用

JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS 2000年第5期17卷 913-920页

作者： Tolstorukov, MY Maleev, VY Kharkov State Univ Chair Mol & Appl Biophys UA-310077 Kharkov Ukraine

A semi-phenomenological model with spatially distributed parameters is suggested to describe the processes of conformational transitions induced with change of water content of wet DNA samples. It allows describing conformational dynamics of DNA molecules with heterogeneous primary structures. It has been shown that the process of cooperative conformational transition can be simulated as propagating front of a new conformation. The evolution of a conformational perturbation of DNA molecule has been described. It can collapse for finite time or occupy the whole molecule depending on the water content of the sample.

关键词： DNA Nucleic Acid Conformation Water 核酸构象水 Nucleic Acid Conformation conformational transition moisture content Theoretical Study distributed parameter DNA

来源：评论

学校读者我要写书评

暂无评论

A new extension of the infinite-dimensional KYP lemma in the coercive case

引用

IFAC-PapersOnLine 2015年第11 11期48卷 246-251页

作者： Proskurnikov, Anton V. ENTEG Institute at the University of Groningen Netherlands St.-Petersburg State University Institute for Problems of Mechanical Engineering RAS ITMO University Russia

The Kalman-Yakubovich-Popov (KYP) Lemma, giving the frequency-domain criteria for solvability of LQR problems and feasibility of related LMIs and Lur'e-Riccati equations, is undoubtedly one of the cornerstone results in modern control theory. Numerous applications of the KYP lemma in nonlinear and robust control motivated its extension to systems with distributed parameters. Unlike the finite-dimensional case, where the KYP lemma admits elegant proofs by means of algebraic techniques and methods from convex analysis, a prerequisite for its infinite-dimensional extensions is feasibility of the corresponding LQR problem, resulting on assumptions of exponential or L2-stabilizability. This property is restrictive and not easily verifiable for general infinite-dimensional systems. Being quite natural in the problems of absolute stability, it seems unnecessary in other applications of the KYP lemma which require only solvability of the operator inequality, but not positivity of its solution, such as e.g. instability or dichotomy criteria. In the present paper we show, that in the “strict” or coercive case the KYP lemma retains its validity, replacing stabilizability assumption with some technical assumption which holds, for instance, whenever the linear system is exponentially dichotomic. © 2015

关键词： Riccati equations Algebra Frequency domain analysis Linear systems Robust control Stability criteria Dissipation inequality distributed parameter Infinite dimensional Infinite dimensional system Kalman Yakubovich Popov lemma KYP lemma Modern control theory Operator inequalities

来源：评论

学校读者我要写书评

暂无评论

Flatness-Based Model Predictive Control with Linear Programming for a Single Mast Stacker Crane

引用

IFAC-PapersOnLine 2018年第2期51卷 31-36页

作者： Galkina, A. Schlacher, K. Institute of Automatic Control and Control Systems Technology Johannes Kepler University Linz Altenberger Strasse 69 Linz4040 Austria

This paper deals with a trajectory tracking model predictive control for a single mast stacker crane, which is used for automatic storage or retrieval of payloads in automated warehouses. The mathematical model of the plant is a distributed parameter one, but it admits an excellent approximation by a flat lumped parameter system. The approximate nonlinear system is simplified further and the resulting linear time-varying system is implemented to design a model predictive controller. To provide an efficient formulation of an optimization task for the controller, the LTV-model is parametrized by a special flat output. Then, the model predictive control is formulated in the form of a linear program. For solving the derived linear program, an open-source optimal solver LP_SOLVE is chosen. To reduce a mechanical stress at clamping of a mast and an overall accessibility time, a special optimal trajectory calculated offline is chosen for the tracking by the designed controller. Finally, the simulation results of the nonlinear approximate model, subjected to model uncertainties and external disturbances, with the designed model predictive controller are presented. © 2018

关键词： Model predictive control Controllers Cranes Linear programming Open source software Time varying control systems Uncertainty analysis distributed parameter Efficient formulation External disturbances Flatness Flexible construction Linear time varying systems Lumped parameter systems Model predictive controllers

来源：评论

学校读者我要写书评

暂无评论

A Monte Carlo method for calculating Bayesian uncertainties in internal dosimetry

引用

RADIATION PROTECTION DOSIMETRY 2008年第1期132卷 1-12页

作者： Puncher, M. Birchall, A. HPA Ctr Radiat Chem & Environm Hazards Radiat Protect Div Didcot OX11 0RQ Oxon England

This paper presents a novel Monte Carlo method (WeLMoS, Weighted Likelihood Monte-Carlo sampling method) that has been developed to perform Bayesian analyses of monitoring data. The WeLMoS method randomly samples parameters from continuous prior probability distributions and then weights each vector by its likelihood (i.e. its goodness of fit to the measurement data). Furthermore, in order to quality assure the method, and assess its strengths and weaknesses, a second method (MCMC, Markov chain Monte Carlo) has also been developed. The MCMC method uses the Metropolis algorithm to sample directly from the posterior distribution of parameters. The methods are evaluated and compared using an artificially generated case involving an exposure to a plutonium nitrate aerosol. In addition to calculating the uncertainty on internal dose, the methods can also calculate the probability distribution of model parameter values given the observed data. In other words, the techniques provide a powerful tool to obtain the estimates of parameter values that best fit the data and the associated uncertainty on these estimates. Current applications of the methodology, including the determination of lung solubility parameters, from volunteer and cohort data, are also discussed.

关键词： Probability distribution Posterior distribution Monte Carlo technique Dosimetry PLUTONIUM NITRATES Volunteers measurement data distributed parameter goodness of fit Markov chain monte carlo methods

来源：评论

学校读者我要写书评

暂无评论

Delays. Nonlinearity. Synchronization

引用

IFAC-PapersOnLine 2016年第10期49卷 200-205页

作者： Danciu, Daniela Rsvan, Vladimir Department of Automation and Electronics University of Craiova A.I. Cuza 13 CraiovaRO-200585 Romania

A rather common model of the synchronization is represented by several local oscillators coupled to some (possibly distributed) transmission environment. This model goes back to Huygens. If the transmission environment is represented by a one dimensional distributed parameter structure (vibrating string in the mechanical case or an electric transmission line for electrical systems) then some functional differential equations may be associated by integration along the characteristics. Consequently, the synchronization of the two local oscillators can be analyzed as a problem of forced oscillations for functional differential equations. In this paper two LC local nonlinear oscillators are viewed as connected to a lossless LC transmission line of infinite length. This is the electrical analogue of the Huygens like case where two nonlinear pendula are coupled to a vibrating string. © 2016

关键词： Electric lines Control nonlinearities Differential equations Oscillators (mechanical) Synchronization Time delay distributed parameter Electrical systems Forced oscillations Functional differential equations Local oscillators Non linear oscillators Popov criteria Transmission environment

来源：评论

学校读者我要写书评

暂无评论

ELASTIC-SCATTERING OF POLARIZED ELECTRONS FROM MERCURY AND XENON

引用

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 1986年第21期19卷 3539-3557页

作者： BERGER, O KESSLER, J Phys. Inst. Munster Univ. West Germany

Polarised electrons have been scattered elastically from mercury and xenon. The angular distribution of the parameters that describe the change in the electron polarisation caused by the scattering process has been measured in the energy range from 25 to 150 eV for mercury and from 40 to 350 eV for xenon. With these parameters, in conjunction with the absolute differential cross section, a complete analysis of the scattering amplitudes with respect to their magnitudes and their relative phase is performed for xenon.

关键词： Scattering elastic scattering ENERGY RANGE Electrons Xenon electron polarization distributed parameter mercury

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：