检索结果-内蒙古大学图书馆

9th IFAC International symposium on dynamics and control of process systems (DYCOPS)/11th IFAC International symposium on Computer Applications in Biotechnology (CAB)

作者： Bernard, Olivier BIOCORE INRIA F-06902 Sophia Antipolis France LOV UPMC CNRS UMR 7093 Stn Zool F-06234 Villefranche Sur Mer France

Oleaginous microalgae are considered to be a potential major biofuel producer in the future since, under conditions of nitrogen deprivation, they are capable of containing high amounts of lipids, while consuming industrial CO2. These photosynthetic microorganisms are, however, rather different from the microorganisms usually used in biotechnology. In particular, predicting the behaviour of microalgal based processes is delicate because of the strong interaction between biology (microalgal development and respiration). and physics (light attenuation and hydrodynamics). This paper reviews existing models, and in particular the Droop model which has been widely used to predict microalgal behaviour under nutrient limitation. It details a model for raceways or planar photobioreactors, when both light and nutrients are limiting. The challenges and hurdles to improve microalgal culture process modelling and control in order to optimise biomass or biofuel production are then discussed. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Microalgae Photobioreactors Raceways Modelling Optimisation Biofuel CO2 mitigation

来源：评论

学校读者我要写书评

暂无评论

A Novel Magnetic-Levitation System: Design, Implementation, and Nonlinear control

引用

IEEE TRANSACTIONS ON PLASMA SCIENCE 2011年第1期39卷 492-497页

作者： Hasirci, Ugur Balikci, Abdulkadir Zabar, Zivan Birenbaum, Leo Gebze Inst Technol Dept Elect Engn TR-41400 Kocaeli Turkey NYU Polytech Inst Dept Elect & Comp Engn New York NY 10004 USA

This paper concerns the design, implementation, and nonlinear velocity-tracking control of a novel magnetic-levitation (maglev) system for magnetically levitated trains. The proposed system uses only one tubular linear induction motor to produce three forces required in a maglev system: propulsion, levitation, and guidance. Classical maglev systems, on the other hand, contain a separate force-generating system to build each of these three forces. Another benefit that the proposed system offers is that there is no need to control the guidance, and particularly, the levitation forces, one of the most challenging tasks in maglev systems. The system always centers the moving part during operation and eliminates the necessity for control of the levitation and guidance forces. However, the propulsion force strongly requires some control efforts because a linear induction motor has nonlinear system dynamics. This paper gives a condensed design guideline based on the mature theory of electromagnetic launchers, particularly the linear induction launcher type. It explains the implementation process, shows experimental test results, and finally, presents a nonlinear partial state-feedback controller for the proposed system.

关键词： Electromagnetic launchers (EMLs) linear induction launchers (LILs) magnetic-levitation (maglev) trains nonlinear control

来源：评论

学校读者我要写书评

暂无评论

LFT-free μ-analysis of LTI/LPTV systems

LFT-free μ-analysis of LTI/LPTV systems

引用

1st Joint symposium on Computer-Aided control System Design, CACSD 2011 and systems with Uncertainty, SU 2011

作者： Zhao, Yun-Bo Kim, Jongrae Bates, Declan G. Biomedical Engineering University of Glasgow Glasgow G12 8QQ United Kingdom Centre for Systems Dynamics and Control College of Engineering Mathematics and Physical Sciences University of Exeter Exeter EX4 4QF United Kingdom

ISBN: (纸本)9781457710667

μ-analysis has for many years been the de facto standard robustness analysis tool in a wide variety of control applications. To use μ-analysis, the uncertain system must be cast in the form of a linear fractional transformation (LFT). Once it is appropriately transformed, a variety of algorithms are available to calculate the upper and the lower bounds on μ. Several difficulties arise during this process. Firstly, the uncertainties in the system must appear as polynomial fractions - if they do not, then some approximation steps must be applied in order to write the system as an LFT. Secondly, symbolic manipulations are required in general in order to obtain linear fractional transformation automatically. Finally, for problems involving real parametric uncertainties calculating the lower bound is a well known NP(Non-deterministic Polynomialtime)-hard problem. Therefore, there will always be some conservatism introduced in the bound or else the computation time will increase exponentially with the number of uncertain parameters. We present an efficient algorithm to overcome these issues by combining a randomisation approach and a geometric interpretation of the robustness analysis problem. The uncertainty is re-defined by a subtraction between the uncertain system and the nominal system. Thus the procedure does not require that the uncertain parameters are actually decoupled from the system (as with LFT's) but only requires the evaluation of the difference between the nominal system and the perturbed system. Here, we illustrate the application of the proposed approach to the robustness analysis of uncertain linear periodically time-varying systems, and in particular to magnetic torquer controlled spacecraft attitude dynamics. © 2011 IEEE.

关键词： Uncertain systems

来源：评论

学校读者我要写书评

暂无评论

control system with evolving Gaussian process models

Control system with evolving Gaussian process models

引用

symposium Series on Computational Intelligence, IEEE SSCI 2011 - 2011 IEEE 5th Workshop on Evolving and Adaptive Intelligent systems, EAIS 2011

作者： Petelin, Dejan Kocijan, Juš Institute Jozef Stefan Jamova cesta 39 SI-1000 Ljubljana Slovenia University of Nova Gorica Vipavska cesta 13 SI-5000 Nova Gorica Slovenia

ISBN: (纸本)9781424499793

control system based on evolving Gaussian process (GP) models is an example of self-learning closed-loop control system. It is meant for closed-loop control of dynamic systems where not much prior knowledge exists or where systems dynamics varies with time or operating region. GP models are non-parametric black-box models which represent a new method for system identification. GP models differ from most other frequently used black-box identification approaches as they do not try to approximate the modeled system by fitting the parameters of the selected basis functions, but rather search for the relationships among measured data. While GP models are Bayesian models, their output is normal distribution, expressed in terms of mean and variance. Latter can be interpreted as a confidence in prediction and used in many fields, especially in control system. Successful control system needs as much as possible data about process to be controlled. If the prior knowledge about the system to be controlled is scarce or the system varies with time or operating region, this control problem can be solved with an iterative method which adapts model with information obtained with streaming data and concurrently optimizes hyperparameter values. While that kind of method for GP models does not yet exist, concepts for evolving GP models and control system based on evolving GP models are proposed in this paper. It is flexible approach within which various ways of model adaptations can be used. One of those possibilities is illustrated with a control of a benchmark problem. © 2011 IEEE.

关键词： Iterative methods

来源：评论

学校读者我要写书评

暂无评论

Application of an extended IHMPC to an unstable reactor system: Study of feasibility and performance

Application of an extended IHMPC to an unstable reactor syst...

引用

9th IFAC International symposium on dynamics and control of process systems (DYCOPS)/11th IFAC International symposium on Computer Applications in Biotechnology (CAB)

作者： Gonzalez, A. H. Adam, E. J. Marcovecchio, M. G. Odloak, D. UNL CONICET INTEC Inst Desarrollo Tecnol Ind Quim RA-3000 Santa Fe Santa Fe Argentina Consejo Nacl Invest Cient & Tecn INGAR Inst Desarrollo & Diseno RA-3000 Santa Fe Santa Fe Argentina Univ Sao Paulo Dept Chem Engn BR-61548 Sao Paulo Brazil

Almost all the theoretical aspects of model predictive control (MPC), such as stability, recursive feasibility and even the optimality are now well established for both, the nominal and the robust case. The stability and recursive feasibility are usually guaranteed by means of additional terminal constraints, while the optimality is achieved considering closed-loop predictions. However, these significant improvements are not always applicable to real processes. An interesting case is the control of open-loop unstable reactor systems. There, the traditional infinite horizon MPC (IHMPC), which constitutes the simplest strategy ensuring stability, needs to include an additional terminal constraint to cancel the unstable modes, producing in this way feasibility problems. The terminal constraint could be an equality or an inclusion constraint, depending on the local controller assumed for predictions. In both cases, however, a prohibitive length of the control horizon is necessary to produce a reasonable domain of attraction for real applications. In this work, we study the application of an IHMPC formulation that has maximal domain of attraction (i.e., the domain of attraction is determined by the system and the constraints, and not by the controller) to an unstable reactor system. It is shown that the method is suitable for real applications in the sense that it accounts for the case of output tracking and it is offset free if the output target is reachable, and minimizes the offset if some of the constraints become active at steady-state. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Model predictive control Domain of attraction Unstable reactor

来源：评论

学校读者我要写书评

暂无评论

Development of grey-box unscented Kalman filter for systems subjected to correlated unmeasured disturbances

Development of grey-box unscented Kalman filter for systems ...

引用

作者： Bavdekar, Vinay A. Patwardhan, Sachin C. Department of Chemical Engineering IIT Bombay Mumbai India

The performance of Bayesian state estimators is dependent on accurate characterisation of the uncertainties in the unmeasured disturbances and in the measurements. The structure of the unmeasured disturbance dynamics is seldom known. Moreover, the disturbances could be correlated in time. In this work a constrained optimisation problem based on the MLE framework is presented to identify the dynamics of the process noise and the covariances of both, the measurement noise and the process noise. The unmeasured process disturbances are modelled as entering the process through known inputs. The efficacy of this approach is tested on a continuous fermenter, which is a benchmark simulation case study. The results on the simulation case study reveal that the proposed approach generates reasonably accurate estimates of the noise dynamics and the covariances. © 2011 Zhejiang University.

关键词： dynamics

来源：评论

学校读者我要写书评

暂无评论

Heat-Exchanger Bypass control

引用

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2011年第2期50卷 965-973页

作者： Luyben, William L. Lehigh Univ Dept Chem Engn Bethlehem PA 18015 USA

Many methods are used for controlling temperatures in heat exchanger systems. Direct manipulation of the flow rate of either the hot or the cold stream is most often used when that stream is a utility (cooling water, steam, hot oil, or refrigerant). When the flow rates of both streams are set by process requirements, heat-exchanger bypassing is widely used. A portion of one of the streams (either hot or cold) is sent through the heat exchanger, and the remainder is bypassed around the exchanger. The temperature of the mixed steam is controlled by valves in each path. This system provides very tight temperature control, since the dynamics of blending a hot stream and a cold stream are very fast. This paper explores the design and control issues when heat-exchanger bypassing is used. The design optimization variables include the fraction of bypassing, the area of the heat exchanger, and the design pressure drops over the control valves. Dynamic rangeability requires heat-transfer rates to be adjustable over a wide range. As expected, results demonstrate that a larger area and more bypassing improve the ratio of maximum-to-design heat transfer rates, which is important for dynamic controllability. An unexpected, counterintuitive result is that control valve design pressure drops have little effect on rangeability in heat-exchanger bypass systems in which variable-speed pumps are used to maintain total flow rates.

关键词： Separation science Liquids Chemical structure Animal feed Water

来源：评论

学校读者我要写书评

暂无评论

Analysis of heterogeneous cell populations: A density-based modeling and identification framework

Analysis of heterogeneous cell populations: A density-based ...

引用

9th IFAC International symposium on dynamics and control of process systems (DYCOPS)/11th IFAC International symposium on Computer Applications in Biotechnology (CAB)

作者： Hasenauer, Jan Waldherr, Steffen Doszczak, Malgorzata Scheurich, Peter Radde, Nicole Allgoewer, Frank Univ Stuttgart Inst Syst Theory & Automat Control Stuttgart Germany Univ Stuttgart Inst Cell Biol & Immunol Stuttgart Germany

In many biological processes heterogeneity within clonal cell populations is an important issue. One of the most striking examples is a population of cancer cells in which after a common, identical death signal some cells die whereas others survive. The reason for this heterogeneity is intrinsic and extrinsic noise. In this paper we present a mechanistic multi-scale modeling framework for cell populations, in which the dynamics of every individual cell is captured by a parameter dependent stochastic differential equation (SDE). Heterogeneity among individual cells is accounted for by differences in parameter values, modeling extrinsic influences. Based on the statistical properties of the extrinsic noise and the SDE model for the individual cell, a partial differential equation (PDE) model is derived. This PDE describes the evolution of the population density. To determine the statistics of the extrinsic noise from experimental population data, a density-based statistical data model of the noise-corrupted data is derived. Employing this data model we show that the statistics of the extrinsic can be computed using a convex optimization. This efficient way of assessing the parameters allows for a so far infeasible uncertainty analysis via bootstrapping. To evaluate the proposed method, a model for the caspase activation cascade is considered. It is shown that for known noise properties the unknown parameter densities in this model are well estimated by the proposed method. 2011 Elsevier Ltd. All rights reserved.

关键词： Cell population Parameter estimation Density estimation Convex optimization Bootstrapping Apoptotic signaling

来源：评论

学校读者我要写书评

暂无评论

Effects of user habituation in keystroke dynamics on password security policy

Effects of user habituation in keystroke dynamics on passwor...

引用

13th IEEE International symposium on High Assurance systems Engineering, HASE 2011

作者： Syed, Zahid Banerjee, Sean Cheng, Qi Cukic, Bojan Lane Department of Computer Science and Electrical Engineering West Virginia University Morgantown WV United States

ISBN: (纸本)9780769546155

Access control systems rely on a variety of methods for authenticating legitimate users and preventing malicious ones from accessing the system. The most commonly used system is a simple username and password approach. This technology has been the de-facto standard for remote authentication applications. A username-password based system assumes that only the genuine users know their own credentials. However, breaching this type of system has become a common occurrence in today's age of social networks and modern computational devices. Once broken, the system will accept every authentication trial using compromised credentials until the breach is detected. In this paper, we explore certain aspects of utilizing keystroke dynamics in username-password based systems. We show that as users get habituated to typing their credentials, there is a significant reduction in the variance of the keystroke patterns. This trend is more pronounced for long and complex passwords as opposed to short dictionary based passwords. We also study the time window necessary to perceive habituation in user typing patterns. Furthermore, we show that habituation plays a key role in classification of genuine login attempts by reducing the equal error rate (EER) over time. Finally, we explore an authentication scheme that employs the security of complex passwords and keystroke dynamics. © 2011 IEEE.

关键词： Authentication

来源：评论

学校读者我要写书评

暂无评论

Heat-Exchanger Bypass control

Heat-Exchanger Bypass Control

引用

International symposium on New Frontiers in Chemical and Biochemical Engineering

作者： Luyben, William L. Lehigh Univ Dept Chem Engn Bethlehem PA 18015 USA

关键词： Blending

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：