Nonlinear dynamic response and buckling of laminated cylindrical shells with axial shallow groov
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ResearchAccelerator PhysicsTom Katsouleas: use of plasmas as novel particle accelerators and light sources Ying Wu: nonlinear dynamics of charged particle beams, coherent radiation sources, and the development of novel accelerators and light sourcesBiological PhysicsNick Buchler: Molecular mechanisms and the evolution of switches and oscillators in gene networks; systems biology; comparative genomicsGlenn Edwards: Interests include 1) the transduction of light to vibrations to heat and pressure in biological systems and 2) how biology harnesses physical mechanisms during pattern formation in early Drosophila development.Gleb Finkelstein: Electronic transport in carbon nanotubes and graphene; Inorganic nanostructures based on self-assembled DNA scaffolds.Henry Greenside: Theoretical neurobiology in collaboration with Dr. Richard Mooney's experimental group on birdsong.Calvin Howell: Measurement of the neutron-neutron scattering length, carbon and nitrogen accumulation and translocation in plants.Joshua Socolar: Organization and function of complex dynamical networks, especially biological networks, including electronic circuits and social interaction networksWarren Warren: novel pulsed techniques, using controlled radiation fields to alter dynamics; ultrafast laser spectroscopy or nuclear magnetic resonanceCondensed Matter PhysicsHarold Baranger: Theory of quantum phenomena at the nanometer scale;many-body effects in quantum dots and wires; conduction through single molecules; quantum computing; quantum phase transitionsRobert Behringer: Experiments on instabilities and pattern formation in fluids; flow, jamming, and stress patterns in granular materials.David Beratan: molecular underpinnings of energy harvesting and charge transport in biology; the mechanism of solar energy capture and conversion in man-made structuresShailesh Chandrasekharan: Theoretical studies of quantum phase transitions using quantum Monte Carlo methods; lattice QCDAlbert Chang: Experiments on quantum transport at low temperature;one-dimensional superconductivity; dilute magnetic semiconductor quantum dots; Hall probe scanning.Patrick Charbonneau: in- and out-of-equilibrium dynamical properties ofself-assembly. Important phenomena, such as colloidal microphase formation, protein aggregation.Stefano Curtarolo: Nanoscale/microscale computing systems & Quantum Information.Gleb Finkelstein: Experiments on quantum transport at low temperature; carbon nanotubes; Kondo effect; cryogenic scanning microscopy; self-assembled DNA templates.Jianfeng Lu: Mathematical analysis and algorithm development for problems from computational physics, theoretical chemistry, material sciences and others. Maiken H. Mikkelsen: Experiments in Nanophysics & Condensed Matter Physics Richard Palmer: Theoretical models of learning and memory in neural networks; glassy dynamics in random systems with frustrated interactions.Joshua Socolar: Theory of dynamics of complex networks; Modeling of gene regulatory networks; Structure formation in colloidal systems; Tiling theory and nonperiodic long-range order.David Smith: theory, simulation and characterization of unique electromagnetic structures, including photonic crystals and metamaterialsStephen Teitsworth: Experiments on nonlinear dynamics of currents in semiconductors.Weitao Yang: developing methods for quantum mechanical calculations of large systems and carrying out quantum mechanical simulations of biological systems and nanostructuresHigh Energy PhysicsAyana Arce: Searches for top quarks produced in massive particle decays, Jet substructure observable reconstruction, ATLAS detector simulation software frameworkAlfred T. Goshaw: Study of Nature's most massive particles, the W and Z bosons (carriers of the weak force) and the top quark.Ashutosh Kotwal: Experimental elementary particle physics; instrumentation, Precisely measure the mass of the W boson, which is sensitive to the quant um mechanical effects of new particles or forces.Mark Kruse: Higgs boson, production of vector boson pairs, andmodel-independent analysis techniques for new particle searches.Seog Oh: High mass di-lepton search, WW and WZ resonance search, A SUSY particle search, HEP detector R&DKate Scholberg: Experimental particle physics and particle astrophysics; neutrino physics with beam, atmospheric and supernova neutrinos (Super-K, T2K, LBNE, HALO, SNEWS)Chris Walter: Experimental Particle Physics, Neutrino Physics,Particle-Astrophysics, Unification and CP ViolationImaging and Medical PhysicsJames T. Dobbins III: advanced imaging applications to improve diagnostic accuracy in clinical imaging, scientific assessment of image quality, developing lower cost imaging for the developing worldBastian Driehuy: developing and applying hyperpolarized gases to enable fundamentally new applications in MRIAlan Johnson: engineering physics required to extend the resolution of MR imaging and in a broad range of applications in the basic sciencesEhsan Samei: design and utilization of advanced imaging techniques aimed to achieve optimum interpretive, quantitative, and molecular performanceWarren Warren: novel pulsed techniques, using controlled radiation fields to alter dynamics; ultrafast laser spectroscopy or nuclear magnetic resonanceNonlinear and Complex SystemsThe Center for Nonlinear and Complex Systems (CNCS) is an interdisciplinar y University-wide organization that fosters research and teaching of nonlinear dynamics, chaos, pattern formation and complex nonlinear systems with many degrees of freedom.Robert Behringer: Experiments on instabilities and pattern formation in fluids; flow, jamming, and stress patterns in granular materials.Patrick Charbonneau: in- and out-of-equilibrium dynamical properties ofself-assembly. Important phenomena, such as colloidal microphase formation, protein aggregation.Henry Greenside: Theory and simulations of spatiotemporal patterns in fluids; synchronization and correlations in neuronal activity associated with bird song. Daniel Gauthier: Experiments on networks of chaotic elements; generation and control of high speed chaos in electronic and optical systems; electrodynamics of cardiac tissue and the onset of fibrillation.Jian-Guo Liu: Applied mathematics, nonlinear dynamics, complex system, fluid dynamics, computational sciencesRichard Palmer: Theoretical models of learning and memory in neural networks; glassy dynamics in random systems with frustrated interactions.Joshua Socolar: Theory of dynamics of random networks with applications to gene regulation; stress patterns in granular materials; stabilization of periodic orbits in chaotic systems.Stephen Teitsworth: Experiments on nonlinear dynamics of currents in semiconductors.Ying Wu: nonlinear dynamics of charged particle beams, coherent radiation sources, and the development of novel accelerators and light sourcesTom Katsouleas: use of plasmas as novel particle accelerators and light sourcesExperimental Nuclear PhysicsThe Duke physics department is the host of the Triangle Universities Nuclear Laboratory consisting of three experimental facilities: LENA, FN tandem Van de Graff, and The High Intensity Gamma Source (HIGS) at the Free Electron Laser Laboratory.Mohammad Ahmed: Study of few nucleon systems with hadronic and gamma-ray probes.Phillip Barbeau: Experimental Nuclear & Particle Astro-Physics, Double Beta Decay, Neutrinos and Dark MatterHaiyan Gao: Neutron EDM, Precision measurement of proton charge radius, Polarized Compton scattering, neutron and proton transversity, search for phi-N bound state, polarized photodisintegration of 3HeCalvin Howell: quantum chromodynamics (QCD) description of structure and reactions of few-nucleon systems, Big Bang and explosive nucleosynthesis, and applications of nuclear physics in biology, medicine and national security Werner Tornow: weak-interaction physics, especially in double-beta decay studies and in neutrino oscillation physics using large scale detectors at the Kamland project in Japan.Henry Weller: Using radiative capture reactions induced by polarized beams of protons and deuterons to study nuclear systemsYing Wu: nonlinear dynamics of charged particle beams, coherent radiation sources, and the development of novel accelerators and light sourcesTheoretical Nuclear and Particle PhysicsSteffen A. Bass: Physics of the Quark-Gluon-Plasma (QGP) and ultra-relativistic heavy-ion collisions used to create such a QGP under controlled laboratory conditions.Shailesh Chandrasekharan: Quantum Critical Behavior in Fermion Systems, Using the generalized fermion bag algorithm, Applications to Graphene and Unitary Fermi Gas.Thomas Mehen: Quantum Chromodynamics (QCD) and the application of effective field theory to hadronic physics.Berndt Müller: Nuclear matter at extreme energy density; Quantum chromodynamics.Roxanne P. Springer: Weak interactions (the force responsible for nuclear beta decay) and quantum chromodynamics (QCD, the force that binds quarks into hadrons).Geometry and Theoretical PhysicsPaul Aspinwall: String theory is hoped to provide a theory of all fundamental physics encompassing both quantum mechanics and general relativity.Hubert Bray: geometric analysis with applications to general relativity and the large-scale geometry of spacetimes.Ronen Plesser: String Theory, the most ambitious attempt yet at a comprehensive theo ry of the fundamental structure of the universe.Arlie Petters: problems connected to the interplay of gravity and light (gravitational lensing, general relativity, astrophysics, cosmology)Quantum Optics/Ultra-cold atomsDaniel Gauthier: Topics in the fields of nonlinear and quantum optics, and nonlinear dynamical systems.Jungsang Kim: Quantum Information & Integrated Nanoscale SystemsMaiken H. Mikkelsen: Experiments in Nanophysics & Condensed Matter Physics∙Duke University Department of Physics∙Physics Bldg., Science Dr.∙Box 90305∙Durham, NC 27708∙Phone: 919-660-2500∙Fax: 919-660-2525NetID LoginE-Newsletter Sign UpSign up to receive a monthly E-Newsletter or an Annual print Newsletter and keep up with the Physics Department’s scholarly activities∙∙∙∙∙DUKE UNIVERSITY∙GIVING @ DUKE∙WORKING ENVIRONMENT POLICY。
Control Systems Engineering Research Report2002Control Systems EngineeringSection CROSS(Control,Risk,Optimization,Stochastics and Systems)Faculty of Information Technology and SystemsDelft University of TechnologyPostal address:Visiting addressP.O.Box5031Mekelweg42600GA Delft2628CD DelftThe Netherlands The NetherlandsPhone:+31-15-2785119Fax:+31-15-2786679Email:control@its.tudelft.nlc 2002Control Systems Engineering,rmation Technology and Systems,Delft University ofTechnologyAll rights reserved.No part of the publication may be reproduced in any form by print,photoprint, microfilm or any other means without written permission from the publisher.Contents1Introduction11.1Overview (1)1.2Address and location (3)1.3Staffin2002 (4)2Intelligent modeling,control&decision making52.1Affordable digitalfly-by-wireflight control systems for small commercial aircraft52.2Intelligent adaptive control of bioreactors (6)2.3Fuzzy control of multivariable processes (7)2.4Neuro-fuzzy modeling in model-based fault detection,fault isolation and con-troller reconfiguration (7)2.5Intelligent molecular diagnostic systems (7)2.6Model based optimization of fed-batch bioprocesses (9)2.7Estimation of respiratory parameters via fuzzy clustering (10)2.8Fuzzy model based control with use of a priori knowledge (10)3Distributed and hybrid systems123.1Modeling and analysis of hybrid systems (12)3.2Model predictive control for discrete-event systems (13)3.3Model predictive control for piece-wise affine systems (13)3.4Model predictive control for hybrid systems (14)3.5Optimal traffic control (14)3.6Advanced control techniques for optimal adaptive traffic control (15)3.7Optimal transfer coordination for railway systems (16)3.8Real-time control of smart structures (17)4Fault-tolerant control194.1Model-based fault detection and controller reconfiguration for wind turbines.194.2Model-based fault detection and identification of sensor and actuator faults forsmall commercial aircraft (20)5Nonlinear analysis,control and identification215.1System identification of bio-technological processes (21)5.2Classification of buried objects based on ground penetrating radar signals..215.3Control of a jumbo container crane(JCC project) (22)5.4X-by-wire (23)5.5Analysis and design of nonlinear control systems for switching networks (24)5.6Bounding uncertainty in subspace identification (25)5.7New passivity properties for nonlinear electro-mechanical systems (26)5.8Relating Lagrangian and Hamiltonian descriptions of electrical circuits (27)5.9Discrete-time sliding mode control (27)5.10Nonlinear control systems analysis (28)5.11Model and controller reduction for nonlinear systems (28)5.12Robust and predictive control using neural networks (29)5.13The standard predictive control problem (30)5.14Predictive control of nonlinear systems in the process industry (30)5.15Identification of nonlinear state-space systems (31)5.16Development of computationally efficient and numerically robust system iden-tification software (32)1Introduction1.1OverviewThis report presents an overview of the ongoing research projects during2002at the Control Systems Engineering(CSE)group of the Faculty of Information Technology and Systems of Delft University of Technology.As revealed by the new logo of the group,a number of major changes have taken place. Three of these major events will be briefly discussed.First,the stronger emphasis on a systems oriented research approach has motivated a change of the name from Control Laboratory into Control Systems Engineering group.Second,in September2001Prof.dr.ir.M.Verhaegen was appointed as the new chairman of the CSE group.With his arrival an impulse was given to strengthen the development of new methods and techniques for identification and fault-tolerant control design.The primary focus of the programme development is to formulate new research initiatives and to initiate research alliances with established Dutch and European research-oriented laboratories and industry.New research proposals will be formulated within the four main themes:intelligent modeling,control and decision making;distributed and hybrid systems;fault-tolerant control; and analysis,control and identification of nonlinear systems—as depicted by the vertical columns in Figure1.The overall focus will remain on complex nonlinear systems,new application directions,however,may be included,such as adaptive optics which more and more rely on advanced control techniques.The CSE group is also taking part in new research programme definitions of the Faculty of Information Technology and Systems,such as the Intelligent Systems Consortium(iSc)chaired by Prof.P.Dewilde.Third,the CSE group strives to strengthen the research and teaching cooperation in the area of control systems engineering with other leading Systems and Control Engineering groups in Delft.To accomplish this goal,the CSE actively supports the creation of a joint Delft Center on Systems and Control Engineering.The research interests of the CSE group are focused on the following areas:•Intelligent modeling,control and decision making:black-box and gray-box modeling of dynamic systems with fuzzy logic and neural net-works,and design of controllers using fuzzy set techniques.•Distributed and hybrid systems:analysis and control methods,multi-agent control,hierarchical control,and model pre-dictive control of hybrid systems.•Fault-tolerant control:fault detection and isolation with system identification and extended Kalmanfiltering, probabilistic robust control.•Nonlinear analysis,control and identification:nonlinear predictive control,sliding mode control,iterative learning control,nonlinear dynamic model inversion,Lagrangian and Hamiltonian modeling and control frame-works(energy based),identification of a composite of numerical local linear state space models to approximate nonlinear dynamics.The goal of the CSE group is to develop innovative methodologies in thefields indicated above.An important motive in demonstrating their relevance is to cooperate with nationalFigure1:Overview of the research topics of the Control System Engineering group. and international research organizations and industry to validate the real-life potential of the new methodologies.The main applicationfields are:•Smart structures:X-by-wire,road traffic sensors,high performance control using smart materials,adaptive optics,laboratory-on-a-chip,micro robotics.•Power engineering:switching networks,power distribution and conversion,condition monitoring in off-shore wind turbines.•Telecommunication•Motion control:autonomous and intelligent mobile systems,mobile robots,container transport,aircraft and satellite control,traffic control.•Bioprocess technology:fermentation processes,waste-water treatment.The CSE group currently consists of27scientific and support staff:8permanent scientific staff,10PhD students,2postdoctoral researchers,and7support personnel.The research activities are for a large partfinanced from external sources including the Dutch National Science Foundation(STW),Delft University of Technology,the European Union,and indus-try.Additional information can be found at http://lcewww.et.tudelft.nl/.1.2Address and locationControl Systems EngineeringFaculty of Information Technology&SystemsDelft University of TechnologyPostal address:P.O.Box50312600GA DelftThe NetherlandsVisiting address:Mekelweg42628CD DelftThe NetherlandsPhone:+31-15-2785119Fax:+31-15-27866791.3Staffin2002Scientific staffProf.dr.ir.M.H.G.VerhaegenProf.dr.ir.J.HellendoornProf.dr.ir.R.Babuˇs kaDr.ir.T.J.J.van den BoomDr.ir.B.De SchutterDr.ir.J.B.KlaassensDr.ir.J.M.A.ScherpenDr.ir.V.VerdultPhD students&postdoctoral researchers Dr.J.Clemente GallardoIr.P.R.FraanjeIr.A.HegyiIr.K.J.G.HinnenIr.D.JeltsemaR.Lopez Lena,MScIr.S.Meˇs i´cIr.M.L.J.OosteromIr.G.PastoreNon-scientific staffC.J.M.DukkerIng.P.M.EmonsP.MakkesIng.W.J.M.van GeestD.NoteboomG.J.M.van der WindtIng.R.M.A.van PuffelenAdvisorsProf.ir.G.Honderd,em.Prof.ir.H.R.van Nauta Lemke,em. Prof.ir.H.B.Verbruggen,em.2Intelligent modeling,control&decision makingThis research theme focuses on the use of fuzzy logic,neural networks and evolutionary al-gorithms in the analysis and design of models and controllers for nonlinear dynamic systems. Fuzzy logic systems offer a suitable framework for combining knowledge of human experts with partly known mathematical models and data,while artificial neural networks are effec-tive black-box function approximators with learning and adaptation capabilities.Evolution-ary algorithms are randomized optimization techniques useful in searching high-dimensional spaces and tuning of parameters in fuzzy and neural systems.These techniques provide tools for solving complex design problems under uncertainty by providing the ability to learn from past experience,perform complex pattern recognition tasks and fuse information from various sources.Application domains include fault-tolerant control,nonlinear system identification, autonomous and adaptive control,among others.2.1Affordable digitalfly-by-wireflight control systems for small commer-cial aircraftProject members:M.L.J.Oosterom,R.Babuˇs ka,H.B.VerbruggenSponsored by:European Community GROWTH project ADFCS–IIThe objective of this project is to apply thefly-by-wire(FBW)technology inflight control systems of a smaller category of aircraft(see Figure2).In FBW digitalflight control systems, there is no direct link between the control stick and pedals,which are operated by the pilot, and the control surfaces.All measured signals,including the pilot inputs,are processed by the flight control computer that computes the desired control surface deflections.This scheme enables theflight control engineer to alter the dynamic characteristics of the bare aircraft through an appropriate design of theflight control laws.Moreover,important safety features can be included in the control system,such asflight envelope protection.This increases the safety level compared to aircraft with mechanical control systems.Our task in the project is to assess the benefits and to verify the validity of the soft-computing techniques in the FBW control system design and sensor management.These novel techniques are combined with standard,well-proven methods of the aircraft industry.Figure2:The Galaxy business jet(left)and validation of the control system through pilot-in-the-loop simulations at the Research Flight Simulator of the NLR(right).Figure3:The experimental laboratory setup(left)and the basic model-based adaptive control scheme(right).The research topics are the design of gain-scheduled control laws,fault detection,isolation and reconfiguration,and an expert system monitoring of the overall operational status of both the pilot and the aircraft.For control design,fault detection and identification system,fuzzy logic approaches are adopted in order to extend linear design techniques to nonlinear systems. Moreover,a neuro-fuzzy virtual sensor will be developed in close cooperation with Alenia to replace hardware sensors.For the pilot-aircraft status monitor a fuzzy expert system will be developed that has the functionality of a warning and advisory/decision aiding system.2.2Intelligent adaptive control of bioreactorsProject members:R.Babuˇs ka,M.Damen,S.Meˇs i´cSponsored by:SenterThe goal of this research is the development and implementation of a robust self-tuning con-troller for fermentation processes.To ensure an optimal operating conditions,the pH value, the temperature and the dissolved oxygen concentration in the fermenter must be controlled within tight bounds.Ideally,the same control unit should be able to ensure the required performance for a whole variety of fermentation processes(different microorganisms),differ-ent scales(volume of1liter to10000liters)and throughout the entire process run.Figure3 shows an experimental laboratory setup used in this project.The main control challenge is the fact that the dynamics of the system depend on the particular process type and scale and moreover are strongly time-varying,due to gradual changes in the process operating conditions.Controllers withfixed parameters cannot fulfill these requirements.Self-tuning(adaptive) control is applied to address the time-varying nature of the process.Among the different types of adaptive controllers(model-free,model-based,gain-scheduled,etc.),the model-based approach is pursued.The model is obtained through a carefully designed local identification experiment.Special attentions is paid to the robustness of the entire system in order to ensure safe and stable operation under all circumstances.The main contribution of this research is the development,implementation and experimental validation of a complete self-tuning control system.The robustness of the system is achieved by combining well-proven identification and control design methods with a supervisory fuzzy expert system.This research is being done a cooperation between Applikon Dependable Instruments B.V.,Schiedam,Faculty of Electrical Engineering,Eindhoven University of Technology and Faculty of Information Technology and Systems and Kluyver Laboratory for Biotechnology, both at Delft University of Technology.2.3Fuzzy control of multivariable processesProject members:R.Babuˇs ka,S.Mollov,H.B.VerbruggenFuzzy control provides effective solutions for nonlinear and partially unknown processes, mainly because of its ability to combine information form different sources,such as avail-able mathematical models,experience of operators,process measurements,etc.Extensive research has been devoted to single-input single-output fuzzy control systems,including mod-eling and control design aspects,analysis of stability and robustness,adaptive control.Mul-tivariable fuzzy control,however,have received considerably less attention,despite strong practical needs for multivariable control solutions,indicated among otherfields from process industry,(waste)water treatment,or aerospace engineering.Yet,theoretical foundations and methodological aspects of multivariable control are not well developed.This research project focuses on the use of fuzzy logic in model-based control of multiple-input,multiple-output(MIMO)systems.Recent developments include effective optimization techniques and robust stability constraints for nonlinear model predictive control.The devel-oped predictive control methods have been applied to the design of an Engine Management System for the gasoline direct injection engine benchmark,developed as a case study within the European research project FAMIMO(see Figure4).An extension of the Relative Gain Array approach has been proposed that facilitates the analysis of interactions in MIMO fuzzy models.2.4Neuro-fuzzy modeling in model-based fault detection,fault isolationand controller reconfigurationProject members:M.H.G.Verhaegen,J.Hellendoorn,R.Babuˇs ka,S.Kanev,A.Ichtev Sponsored by:STWMost fault tolerant control systems rely on two modules:(model-based)fault detection and isolation module and controller reconfiguration module.The two key elements in designing these two systems are the development of a mathematical model and a suitable decision mechanism to localize the failure and to select a new controller configuration.This project focuses on the development of a design framework in which the mathematical model and the corresponding observer are represented as a composition of local models,each describing the system in a particular operating regime or failure mode.The use of fuzzy Takagi-Sugeno models for residual generation has been investigated.On the basis of residuals soft fault detection and isolation and controller reconfiguration are performed.2.5Intelligent molecular diagnostic systemsProject members:L.Wessels,P.J.van der Veen,J.HellendoornAir BurngasesFigure4:Fuzzy predictive control of a gasoline directinjection engine. Sponsored by:DIOC-5:Intelligent Molecular Diagnostic SystemsIt is the goal of the DIOC-5(DIOC:Delft Interfaculty Research Center)program to produce an Intelligent Molecular Diagnostic System(IMDS).The IMDS will consist of two basic com-ponents:a measurement device and an information processing unit(IPU).The measurement device is a chemical sensor on a chip,which will be capable of rapidly performing vast num-bers of measurements simultaneously,consuming a minimal amount of chemical reagents and sample(see Figure5).Figure5:A prototype IMDS chip containing a matrix of25pico-liter wells.The IPU transforms the complex,raw measurements obtained from the sensor into output that can be employed as high-level decision support in various application domains.See[41]for a possible realization of the IPU.Members of the Control Systems Engineering group and the Information and Communica-tion Theory group are responsible for the realization of the Information Processing Unit.Un-raveling the metabolic processes and the associated regulatory mechanisms of yeast is a very interesting application area for the DIOC-5technology.We are focusing on problems associ-ated with gene and protein levels,and will integrate this information with existing knowledge about metabolic processes developed at the Kluyver Laboratory(One of the DIOC-5part-ners).More specifically,gene expression data and protein concentration measurements are employed to model the genetic networks,i.e.,to postulate possible‘genetic wiring diagrams’based on the expression data(See[40]for some preliminary results in this area.) It is envisaged that at the end of this project,genetic network information,protein func-tional knowledge and metabolic models can be integrated into a single hierarchical model, capable of providing metabolic engineers with greater insight into the yeast metabolism.For additional information see the IMDS Web page.12.6Model based optimization of fed-batch bioprocessesProject members:J.A.Roubos,P.Krabben,R.Babuˇs ka,J.J.Heijnen,H.B.Verbruggen Sponsored by:DIOC-6:Mastering the Molecules in Manufacturing,DSM Anti Infectives Many biotechnological production systems are based on batch and fed-batch processes.Op-timization of the product formation currently requires a very expensive and time consuming experimental program to determine the optima by trial and error.The aim of this project is to find a more efficient development path for fed-batch bioprocesses by an optimal combination of experiments and process models.The two main research topics of this project are:•Development of a user friendly modeling environment for fed-batch processes.The soft-ware tool must be able to use different types of knowledge coming from experts,experi-ments andfirst-principles,i.e.,conservation laws.New modeling methods such as fuzzy logic,neural networks and hybrid models will be used.•Iterative optimal experiment design.First some basic experiments can be done to esti-mate some preliminary parameters for the system.The idea is to make a rough model to design the next experiment.First,a stoichiometric model is made and thereafter a structured biochemical model that will be gradually improved according to the fermen-tation data.The main objective is to predict the right trends.The actual values are less important at the initial stages.Once the model is sufficient in terms of quantitative prediction of the production process for a variable external environment,it will be used to determine optimal feeding strategies for the reactor in order to improve product quality and/or quantity.These feeding strategies will be applied in an on-line process control environment.Recent developments and publications can be found at the project Web page2.1http://www.ph.tn.tudelft.nl/Projects/DIOC/Progress.html2http://lcewww.et.tudelft.nl/˜roubos/02401020Time [s]p h a s e 1p h a s e 2p h a s e 3phase 4P r e s s u r e [h P a ]Figure 6:Partitioning of the respiratory cycle is obtained automatically by fuzzy clustering.Each segment represents a characteristic phase of the respiratory cycle.2.7Estimation of respiratory parameters via fuzzy clusteringProject members:R.Babuˇs ka,M.S.Lourens,A.F.M.Verbraak and J.Bogaard (University Hospital Rotterdam)The monitoring of respiratory parameters estimated from flow-pressure-volume measurements can be used to assess patients’pulmonary condition,to detect poor patient-ventilator interac-tion and consequently to optimize the ventilator settings.A new method has been investigated to obtain detailed information about respiratory parameters without interfering with the ven-tilation.By means of fuzzy clustering,the available data set is partitioned into fuzzy subsets that can be well approximated by linear regression models locally.Parameters of these models are then estimated by least-squares techniques.By analyzing the dependence of these local parameters on the location of the model in the flow-volume-pressure space,information on the patients’pulmonary condition can be gained.The effectiveness of the proposed approaches has been studied by analyzing the dependence of the expiratory time constant on the volume in patients with chronic obstructive pulmonary disease (COPD)and patients without COPD.2.8Fuzzy model based control with use of a priori knowledgeProject members:R.Babuˇs ka,J.Abonyi (University of Veszpr´e m,Hungary)Effective development of nonlinear dynamic process models is of great importance in the application of model-based control.Typically,one needs to blend information from different sources:experience of operators and designers,process data and first principle knowledge formulated by mathematical equations.To incorporate a priori knowledge into data-driven identification of dynamic fuzzy models of the Takagi-Sugeno type a constrained identification algorithm has been developed,where the constrains on the model parameters are based on the knowledge about the process stability,minimal or maximal gain,and the settling time.The algorithm has been successfully applied to off-line and on-line adaptation of fuzzy models.When no a priori knowledge about the local dynamic behavior of the process is available, information about the steady-state characteristic could be extremely useful.Because of the difficult analysis of the steady-state behavior of dynamic fuzzy models of the Takagi-Sugeno type,block-oriented fuzzy models have been developed.In the Fuzzy Hammerstein(FH) model,a static fuzzy model is connected in series with a linear dynamic model.The obtained FH model is incorporated in a model-based predictive control scheme.Results show that the proposed FH modeling approach is useful for modular parsimonious modeling and model-based control of nonlinear systems.3Distributed and hybrid systemsHybrid systems typically arise when a continuous-time system is coupled with a logic con-troller,or when we have a system in which external inputs or internal events may cause a sudden change in the dynamics of the system.So hybrid systems exhibit both continuous-variable and discrete-event behavior.Due to the intrinsic complexity of hybrid systems control design techniques for hybrid systems we could either focus on special subclasses of hybrid sys-tems,or use a distributed or hierarchical approach to decompose the controller design problem into smaller subproblems that are easier to solve.In our research we use both approaches.3.1Modeling and analysis of hybrid systemsProject members:B.De Schutter,W.M.P.H.Heemels(Eindhoven University of Technology), A.Bemporad(ETH Z¨u rich)Hybrid systems arise from the interaction between continuous-variable systems(i.e.,systems that can be described by a system of difference or differential equations)and discrete-event systems(i.e.,asynchronous systems where the state transitions are initiated by events;in general the time instants at which these events occur are not equidistant).In general we could say that a hybrid system can be in one of several modes whereby in each mode the behavior of the system can be described by a system of difference or differential equations, and that the system switches from one mode to another due to the occurrence of an event (see Figure7).We have shown that several classes of hybrid systems:piecewise-affine systems,mixed logical dynamical systems,complementarity systems and max-min-plus-scaling systems are equivalent[6,7,24,25].Some of the equivalences are established under(rather mild)addi-tional assumptions.These results are of paramount importance for transferring theoreticalFigure7:Schematic representation of a hybrid system.properties and tools from one class to another,with the consequence that for the study of a particular hybrid system that belongs to any of these classes,one can choose the most convenient hybrid modeling framework.Related research is described under Project3.3.In addition,we have also shown an equivalence between two type of mathematical pro-gramming problems:the linear complementarity problem(LCP)and the extended linear complementarity problem(ELCP)[17].More specifically,we have shown that an ELCP with a bounded feasible set can be recast as an LCP.This result allows us to apply existing LCP algorithms to solve ELCPs[16].3.2Model predictive control for discrete-event systemsProject members:B.De Schutter,T.J.J.van den BoomModel predictive control(MPC)is a very popular controller design method in the process industry.An important advantage of MPC is that it allows the inclusion of constraints on the inputs and ually MPC uses linear discrete-time models.In this project we extend MPC to a class of discrete-event systems.Typical examples of discrete-event systems are:flexible manufacturing systems,telecommunication networks,traffic control systems, multiprocessor operating systems,and logistic systems.In general models that describe the behavior of a discrete-event system are nonlinear in conventional algebra.However,there is a class of discrete-event systems–the max-plus-linear discrete-event systems–that can be described by a model that is“linear”in the max-plus algebra.We have further developed our MPC framework for max-plus-linear discrete-event systems and included the influences of noise and disturbances[33,34,35,36,37].In addition,we have also extended our results to discrete-event systems that can be described by models in which the operations maximization,minimization,addition and scalar multiplication appear[22], and to discrete-event systems with both hard and soft synchronization constraints[19](see also Project3.7).3.3Model predictive control for piece-wise affine systemsProject members:B.De Schutter,T.J.J.van den BoomWe have extended our results on model predictive control(MPC)for discrete event systems (see Project3.2)to a class of hybrid systems that can be described by a continuous piecewise-affine state space model.More specifically,we have considered systems of the formx(k)=P x(x(k−1),u(k))y(k)=P y(x(k),u(k)),where x,u and y are respectively,the state,the input and the output vector of the system,and where the components of P x and P y are continuous piecewise-affine(PWA)scalar functions,i.e.,functions that satisfy the following conditions:1.The domain space of f is divided into afinite number of polyhedral regions;2.In each region f can be expressed as an affine function;3.f is continuous on any boundary between two regions.。
振 动 与 冲 击第18卷第1期JOU RNAL O F V I BRA T I ON AND SHOCK V o l.18N o.11999 Jeffcot转子2滑动轴承系统不平衡响应的非线性仿真Ξ王德强 张直明(山东省内燃机研究所) (上海大学轴承研究室)摘 要 本文用动力仿真法考察了Jeffco t转子2椭圆轴承系统的不平衡响应。
计入了轴承油膜力的非线性。
仿真计算前,先以非定常雷诺方程和雷诺破膜条件为依据,生成了轴瓦非定常油膜力数据库。
用龙格2库塔法对运动方程作步进积分,同时反复对轴瓦力数据库进行插值以获得轴承力的瞬时值。
考察了支撑于一对椭圆轴承上的Jeffco t转子的不平衡响应。
所得的动力学行为以及转子和轴颈的涡动轨迹,均与线性动力学(以轴承的线性化动特性系数为依据)所得的结果相比较。
两者虽在很小的不平衡量下吻合良好,但凡当不平衡量不是很小时就有显著差别。
可见有必要计入油膜力的非线性,特别是当需要计算大不平衡量下的不平衡响应时。
关键词:非线性仿真,不平衡响应,转子动力学中图分类号:TH11330 前 言在工程实践中,常常用线性动力理论来计算转子2滑动轴承系统的不平衡响应,即:计算时以线性化的轴承动力特性(轴承的八个刚度和阻尼)来表达轴承油膜的动态力[1]。
但油膜力实际上是非线性的动力元素,因此这样的线性化不可避免地要导致不平衡响应计算中的误差。
本文目的在于用非线性和线性动力学两种计算来考察不平衡响应,并作比较,以明确其异同。
符 号c m in 轴承最小半径间隙(m) x j、y j 以c m in为参考的轴颈中心坐标无量纲值d轴承直径(m)x r、y r以c m in为参考的转子中心坐标无量纲值e u转子质量中心的偏心距(m)Λ润滑油的动力粘度(Pa.s)E u质量中心的相对偏心(e u c m in)F轴承的静载荷(N)f轴在自重下的静挠度(m)Ξ转子角速度Γ轴的相对挠度(f c m in)Ξk转子固有频率l轴承长度(m)8相对速度(Ξ Ξk)SO k以转子固有频率为参考的轴承7m in轴承的最小间隙化Somm erfeld数7m in=c m in rSO k=FΩ3m in d lΛΞk1 线性分析本文以Jeffco t转子2轴承系统(图1)为考察对象。
未折叠蛋白反应在强噪声致豚鼠耳蜗细胞损伤过程中的作用薛秋红;陈小林;龚树生;谢静;陈佳;何坚【摘要】Objective To study the unfolded protein glucose-regulated protein 78 (GRP78) expression level after intense noise exposure,and to find out the relationship between UPR and the intense noise induced cochlea cell damage. Methods Forty-eight guinea pigs were randomly divided into 6 groups(8 guinea pigs/group). The guinea pigs in the experiment groups were exposed to 4 kHz narrow band noise at 120 dB SPL for 4 housr while aninals in control group received no noise exprsure. Auditory brainstem response(ABR) of the guinea pigs in experiment and control groups were tested at 3 hours, 1, 4, 14,30 days post noise exposure. Four guinea pig's cochleas from each group were used for paraffin sectioning, and the rest was used for the total protein extraction. Expression of Bip/GRP78 was studied by immunohistochemistry sectioning and western blot. Results There were significantly higher expressions of Tunel-Positve cells in the OHC,SGC and SV in experiment groups compared with those in the controi group (P<0.01). Protein levels ofBip/GRP78 were significantly increased after noise exposure compared with those in the control group (P<0.01). Conclusion After intense noise exposure, UPR protection mechanisms were initiated and by upregulating the expression of molecular chaperones Bip/GRP78, folded proteins were correctly guided, thus reducing cell damage. This may be one of the endogenous protective mechanisms in the guinea pig cochlea.%目的探讨未折叠蛋白反应(unfolded protein response,UPR)标志物葡萄糖调节蛋白78(Bip/GRP78)在强噪声致豚鼠耳蜗细胞损伤中的作用.方法 48只豚鼠随机分为6组,分别为健康对照组(不给噪声暴露)和强噪声暴露后3 h、1 d、4 d、14 d、30 d 组,每组8只,噪声暴露的5组豚鼠在120 dB SPL、4 kHz窄带噪声环境暴露4 h 后,各组豚鼠于相应时间点处死前及对照组均测试听性脑干反应(ABR),然后每组各取4只豚鼠耳蜗作石蜡切片,余4只豚鼠提取耳蜗总蛋白.用免疫组化及Western Blot方法检测Bip/GRP78的表达及其在耳蜗的分布.结果强噪声暴露后各组Bip/GRP78蛋白表达明显高于正常组,且各时间点都维持在比较高的水平,Bip/GRP78蛋白在噪声暴露后各组豚鼠耳蜗的内外毛细胞、螺旋神经节细胞、侧壁细胞均有表达.结论强噪声暴露后,启动UPR保护机制,通过上调分子伴侣Bip/GRP78的表达,引导蛋白质正确折叠,降低细胞损伤,可能是耳蜗内源性保护机制之一.【期刊名称】《听力学及言语疾病杂志》【年(卷),期】2011(019)002【总页数】4页(P149-152)【关键词】未折叠蛋白反应;葡萄糖调节蛋白78;强噪声;耳蜗;损伤【作者】薛秋红;陈小林;龚树生;谢静;陈佳;何坚【作者单位】武汉科技大学附属天佑医院耳鼻咽喉科,武汉,430064;武汉科技大学附属天佑医院耳鼻咽喉科,武汉,430064;首都医科大学附属北京同仁医院耳鼻咽喉头颈外科;武汉科技大学附属天佑医院耳鼻咽喉科,武汉,430064;武汉科技大学附属天佑医院耳鼻咽喉科,武汉,430064;武汉科技大学附属天佑医院耳鼻咽喉科,武汉,430064【正文语种】中文【中图分类】R764.43+3内质网是细胞加工蛋白质和储存钙离子的场所,许多理化因素可以导致未折叠或错误折叠蛋白质在内质网的蓄积以及细胞内钙稳态的失衡,这种状态称为内质网应激,近年来有关内质网应激的信号通路与效应的研究已成为热点。
文章编号:1000-4750(2021)04-0247-10基于向量有限元的深水管道屈曲行为分析李振眠1,2,余 杨1,2,余建星1,2,赵 宇1,2,张晓铭1,2,赵明仁1,2(1. 天津大学水利工程仿真与安全国家重点实验室,天津大学,天津 300350;2. 天津市港口与海洋工程重点实验室,天津大学,天津 300350)摘 要:局部屈曲破坏是深水管道运行的最大安全问题之一。
采用创新性的向量式有限元方法(VFIFE)分析深水管道结构屈曲行为,推导考虑材料非线性的VFIFE 空间壳单元计算公式,编制Fortran 计算程序和MATLAB 后处理程序,开展外压下深水管道压溃压力和屈曲传播压力计算、压溃和屈曲传播过程模拟。
开展全尺寸深水管道压溃试验,进行深水管道压溃压力和压溃形貌分析,对比验证了VFIFE 、试验、传统有限元方法(FEM)得到的结果。
结果表明:VFIFE 能够直接求解管道压溃压力和屈曲传播压力,模拟管道屈曲和屈曲传播行为,计算结果符合实际情况,与压溃试验、传统有限元方法符合较好,并具有不需特殊计算处理、全程行为跟踪等优势,可以为深水管道结构屈曲行为分析提供一套新的、通用的分析策略。
关键词:管道结构;屈曲行为;向量式有限元;空间壳单元;压力舱试验中图分类号:TU312+.1;P756.2 文献标志码:A doi: 10.6052/j.issn.1000-4750.2020.06.0357BUCKLING ANALYSIS OF DEEPWATER PIPELINES BY VECTOR FORMINTRINSIC FINITE ELEMENT METHODLI Zhen-mian 1,2, YU Yang 1,2, YU Jian-xing 1,2, ZHAO Yu 1,2, ZHANG Xiao-ming 1,2, ZHAO Ming-ren1,2(1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300350, China;2. Tianjin Key Laboratory of Port and Ocean Engineering, Tianjin University, Tianjin 300350, China)Abstract: Local buckling damage is one of the biggest safety issues during the operation of deepwater pipelines.The innovative vector form intrinsic finite element method (VFIFE) is used to analyze the buckling behavior of deepwater pipelines. After deriving the calculation formula of VFIFE space shell elements considering the nonlinear elastoplastic material, we developed a Fortran calculation program and a MATLAB post-processing program to simulate the collapse and buckling propagation process. The collapse pressure and the buckling propagation pressure were calculated. A full-scale pressure chamber test was conducted to analyze the buckling load and buckling morphology. The VFIFE results were compared with those of the test, traditional finite element method (FEM) and DNV method. The VEIFE can directly simulate the pipeline collapse, the buckling propagation, the collapse pressure, and the buckling propagation pressure. The VFIFE results are in line with the actual situation and in good agreement with those of the other methods. The VFIFE has the advantages of not requiring special calculation processing and tracking of the entire behavior, thus providing a new and universal analytic strategy for buckling simulation of deepwater pipelines.Key words: pipeline structure; buckling behavior; vector form intrinsic finite element method; 3D shell element;pressure chamber test深水管道由于外部高静水压作用,其设计通常依据局部屈曲压溃的失稳极限状态[1]。
自适应密度峰值聚类算法
张强;周水生;张颖
【期刊名称】《西安电子科技大学学报》
【年(卷),期】2024(51)2
【摘要】密度峰值聚类(DPC)以其简单、高效的特点被广泛应用。
然而,其有两个不足:(1)集群密度不均匀和不平衡的数据集在DPC所提供的决策图中,很难识别真正的聚类中心;(2)存在一个区域密度最高的点的错误分配将导致该区域内的所有点都指向同一个错误的聚类的“链式效应”。
针对这两个不足,引入新的自然邻域(NaN)的概念,提出了一种基于自然邻域的密度峰值聚类算法(DPC-NaN)。
算法使用新的自然邻域密度识别噪声点,选择初始预聚类中心点,将非噪声点按密度峰值方法进行分配以得到预聚类;并通过确定预聚类的边界点和合并半径,自适应地将预聚类结果合并为最终聚类。
所提算法无需人工预设参数,也缓解了“链式效应”的问题。
实验结果表明,与相关聚类算法相比,所提出的算法可在典型的数据集上获得更好的聚类结果,同时在图像分割表现良好。
【总页数】12页(P170-181)
【作者】张强;周水生;张颖
【作者单位】西安电子科技大学数学与统计学院
【正文语种】中文
【中图分类】TP391
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Materials failure modes BucklingCorrosionCreepFatigueFoulingFractureImpactMechanical overload Thermal shockWearYielding BucklingFrom Wikipedia, the free encyclopediaIn science, buckling is a mathematical instability, leading to a failuremode. Theoretically, buckling is caused by a bifurcation in the solution tothe equations of static equilibrium. At a certain stage under an increasingload, further load is able to be sustained in one of two states of equilibrium:an undeformed state, or a laterally-deformed state. In practice, buckling ischaracterized by a sudden failure of a structural member subjected to highcompressive stress, where the actual compressive stress at the point offailure is less than the ultimate compressive stresses that the material iscapable of withstanding. For example, during earthquakes, reinforcedconcrete members may experience lateral deformation of the longitudinalreinforcing bars. This mode of failure is also described as failure due toelastic instability. Mathematical analysis of buckling makes use of an axialload eccentricity that introduces a moment, which does not form part of theprimary forces to which the member is subjected. When load is constantlybeing applied on a member, such as column, it will ultimately becomelarge enough to cause the member to become unstable. Further load willcause significant and somewhat unpredictable deformations, possiblyleading to complete loss of load-carrying capacity. The member is said tohave buckled, to have deformed.Contents1 Columns■1.1 Self-buckling■2 Limit point vs bifurcation buckling■3 Bicycle wheels■4 Surface materials■5 Energy method■6 Flexural-torsional buckling■7 Lateral-torsional buckling■8 Plastic buckling■9 Dynamic buckling■10 Buckling of thin cylindrical shells subject to axial loads■11 Buckling of pipes and pressure vessels subject to external overpressure■12 References■13 See also■ColumnsThe ratio of the effective length of a column to the least radiusof gyration of its cross section is called the slenderness ratio(sometimes expressed with the Greek letter lambda, λ). Thisratio affords a means of classifying columns. Slenderness ratiois important for design considerations. All the following areapproximate values used for convenience.A column under a concentric axial load exhibiting the characteristic deformation of bucklingThe eccentricity of the axial force results in a bending moment acting on the beam element.A short steel column is one whose slenderness ratio does notexceed 50; an intermediate length steel column has a slenderness ratio ranging from about 50 to 200, and aredominated by the strength limit of the material, while a long steel column may be assumed to have a slenderness ratio greater than 200.■A short concrete column is one having a ratio of unsupportedlength to least dimension of the cross section not greater than 10. If the ratio is greater than 10, it is a long column (sometimes referred to as a slender column).■Timber columns may be classified as short columns if the ratioof the length to least dimension of the cross section is equal to or less than 10. The dividing line between intermediate and long timber columns cannot be readily evaluated. One way of defining the lower limit of long timber columns would be to set it as the smallest value of the ratio of length to least cross sectional area that would just exceed a certain constant K of the material. Since K depends on the modulus of elasticity and the allowable compressive stress parallel to the grain, it can be seen that this arbitrary limit would vary with the species of the timber. The value of K is given in most structural handbooks.■If the load on a column is applied through the center of gravityof its cross section, it is called an axial load. A load at anyother point in the cross section is known as an eccentric load. A short column under the action of anaxial load will fail by direct compression before it buckles, but a long column loaded in the same manner will fail by buckling (bending), the buckling effect being so large that the effect of the directload may be neglected. The intermediate-length column will fail by a combination of direct compressive stress and bending.In 1757, mathematician Leonhard Euler derived a formula that gives the maximum axial load that a long, slender, ideal column can carry without buckling. An ideal column is one that is perfectly straight, homogeneous, and free from initial stress. The maximum load, sometimes called the critical load, causes the column to be in a state of unstable equilibrium; that is, any increase in the load, or the introduction of the slightest lateral force, will cause the column to fail by buckling. The formula derived by Euler for columns with no consideration for lateral forces is given below. However, if lateral forces are taken into consideration the value of critical load remains approximately thesame.E = modulus of elasticity,I = area moment of inertia,L = unsupported length of column,K = column effective length factor, whose value depends on the conditions of end support of the column, as follows.For both ends pinned (hinged, free to rotate), K = 1.0.For both ends fixed, K = 0.50.For one end fixed and the other end pinned, K = 0.699....For one end fixed and the other end free to move laterally, K = 2.0.A demonstration model illustrating the different "Euler" buckling modes. The model shows how the boundary conditions affect the critical load of a slender column. Notice that each of the columns are identical, apart from the boundary conditions.KL is the effective length of the column.Examination of this formula reveals the following interesting facts with regard to the load-bearing ability of slender columns.Elasticity and not compressive strength of the materials of the column determines the critical load.1.The critical load is directly proportional to the second moment of area of the cross section.2.The boundary conditions have a considerable effect on the critical load of slender columns. The boundary conditions determine the mode of bending and the distance between inflection points on the deflected column. The closer together the inflection points are, the higher the resulting capacity of the column.3.The strength of a column may therefore be increased by distributing the material so as to increase the moment ofinertia. This can be done without increasing the weight of the column by distributing the material as far from theprincipal axes of the cross section as possible, while keeping the material thick enough to prevent localbuckling. This bears out the well-known fact that a tubular section is much more efficient than a solid section for column service.Another bit of information that may be gleaned from this equation is the effect of length on critical load. For agiven size column, doubling the unsupported length quarters the allowable load. The restraint offered by theend connections of a column also affects the critical load. If the connections are perfectly rigid, the critical load willbe four times that for a similar column where there is no resistance to rotation (hinged at the ends).Since the moment of inertia of a surface is its area multiplied by the square of a length called the radius ofgyration, the above formula may be rearranged as follows. Using the Euler formula for hinged ends, and substituting A·r 2 for I, the followingformula results.where F / A is the allowable stress of the column, and l / r is the slenderness ratio.Since structural columns are commonly of intermediate length, and it is impossible to obtain an ideal column, the Euler formula on its own has little practical application for ordinary design. Issues that cause deviation from the pure Euler strut behaviour include imperfections in geometry in combination with plasticity/non-linear stress strain behaviour of the column's material. Consequently, a number of empirical column formulae have been developed to agree with test data, all of which embody the slenderness ratio. For design, appropriate safety factors are introduced into these formulae.Self-bucklingA free-standing, vertical column, with density ρ, Young's modulus E , and radius r , will buckle under its own weight if its height exceeds a certain critical height:[1][2][3]where g is the acceleration due to gravity, I is the second moment of area of the beam cross section, and B is the first zero of the Bessel function of the first kind of order-1/3, which is equal to 1.86635...Limit point vs bifurcation bucklingBifurcation buckling[4][5] is sometimes called Euler buckling even when applied to structures other than Euler columns. As the applied load is increased by a small amount beyond the critical load, the structure deforms into a buckled configuration which is adjacent to the original configuration. For example, the Euler column pictured will start to bow when loaded slightly above its critical load, but will not suddenly collapse.In structures experiencing limit point instability, if the load is increased infinitesimally beyond the critical load, the structure undergoes a large deformation into a different stable configuration which is not adjacent to the original configuration. An example of this type of buckling is a toggle frame (pictured) which 'snaps' into its buckled configuration.Sun kink in rail tracks Bicycle wheelsA conventional bicycle wheel consists of a thin rim kept under high compressive stress by the(roughly normal) inward pull of a large number of spokes. It can be considered as a loaded column that has been bent into a circle. As such, if spoke tension is increased beyond a safe level, the wheel spontaneously fails into a characteristic saddle shape (sometimes called a "taco" or a "pringle") like a three-dimensional Euler column. This is normally a purely elastic deformation and the rim will resume its proper plane shape if spoke tension is reduced slightly.Surface materialsBuckling is also a failure mode in pavement materials,primarily with concrete, since asphalt is more flexible. Radiant heat from the sun is absorbed in the road surface,causing it to expand, forcing adjacent pieces to push against each other. If the stress is great enough, thepavement can lift up and crack without warning. Going over a buckled section can be very jarring to automobiledrivers, described as running over a speed hump at highway speeds.Similarly, rail tracks also expand when heated, and can fail by buckling, a phenomenon called sun kink. It is morecommon for rails to move laterally, often pulling the underlain railroad ties (sleepers) along .Energy methodOften it is very difficult to determine the exact buckling load in complex structures using the Euler formula, due to the difficulty in deciding the constant K. Therefore, maximum buckling load often is approximated using energy conservation. This way of deciding maximum buckling load is often referred to as the energy method in structural analysis.The first step in this method is to suggest a displacement function. This function must satisfy the most important boundary conditions, such as displacement and rotation. The more accurate thedisplacement function, the more accurate the result.In this method, there are two equations used to approximate the inner energy and outer energy (forsmall deformations).where w (x ) is the displacement function and the subscripts x and xx refer to the first and secondderivatives of the displacement. Energy conservation yields:Lateral-torsional buckling of an aluminium alloy plate girder Flexural-torsional bucklingOccurs in compression members only and it can be described as a combination of bending andtwisting of a member. And it must be consider for design purposes, since the shape and cross sections are very critical. This mostly occurs in channels, structural tees, double-angle shapes, and equal-leg single angles.Lateral-torsional bucklingWhen a simple beam is loaded in flexure, the top side is incompression, and the bottom side is in tension. When a slender member is subjected to an axial force, failure takes place due tobending or torsion rather than direct compression of the material. If the beam is not supported in the lateral direction (i.e.,perpendicular to the plane of bending), and the flexural load increases to a critical limit, the beam will fail due to lateralbuckling of the compression flange. In wide-flange sections, if the compression flange buckles laterally, the cross section willalso twist in torsion, resulting in a failure mode known as lateral-torsional buckling .Plastic bucklingBuckling will generally occur slightly before the theoretical buckling strength of a structure, due to plasticity of the material. When the compressive load is near buckling, the structure will bow significantly and approach yield. The stress-strain behaviourof materials is not strictly linear even below yield, and the modulus of elasticity decreases as stress increases, with more rapid change near yield. This lower rigidity reduces the buckling strength of the structure and causes premature buckling. This is the opposite effect of the plastic bending in beams, which causes late failure relative to the Euler-Bernoulli beam equation.Dynamic bucklingIf the load on the column is applied suddenly and then released, the column can sustain a load much higher than its static (slowly applied) buckling load. This can happen in a long, unsupported column (rod) used as a drop hammer. The duration of compression at the impact end is the time required for a stress wave to travel up the rod to the other (free) end and back down as a relief wave. Maximum buckling occurs near the impact end at a wavelength much shorter than the length of the rod, at a stress many times the buckling stress if the rod were a statically-loaded column. The critical condition for buckling amplitude to remain less than about 25 times the effective rod straightness imperfectionat the buckle wavelength isBuckling of thin cylindrical shells subject to axial loadsSolutions of Donnel's eight order differential equation gives the various buckling modes of a thin cylinder under compression. But this analysis, which is in accordance with the small deflection theory gives much higher values than shown from experiments. So it is customary to find the critical buckling load for various structures which are cylindrical in shape from pre-existing design curves where critical buckling load F cr is plotted against the ratio R/t, where R is the radius and t is thethickness of the cylinder for various values of L/R, L the length of the cylinder. If cut-outs are present in the cylinder, critical buckling loads as well as pre-buckling modes will be affected. Presence or absence of reinforcements of cut-outs will also affect the buckling load.Buckling of pipes and pressure vessels subject to external overpressurePipes and pressure vessels subject to external overpressure, caused for example by steam cooling down and condensating into water with subsequent massive pressure drop, risk buckling due to compressive hoop stresses. Design rules for calculation of the required wall thickness or reinforcement rings are given in various piping and pressure vessel codes.References^ Kato, K. (1915). "Mathematical Investigation on the Mechanical Problems of Transmission Line". Journal of the Japan Society of Mechanical Engineers 19: 41.1.^ Ratzersdorfer, Julius (1936). Die Knickfestigkeit von Stäben und Stabwerken . Wein, Austria:J. Springer. pp. 107–109.2.^ Cox, Steven J.; C. Maeve McCarthy (1998). "The Shape of the Tallest Column". Society for Industrial and Applied Mathematics 29: 547–554.3.^ "Buckling of Bars, Plates, and Shells" By Robert M. Jones4.^ "Observations on eigenvalue buckling analysis within a finite element context" by Christopher J. Earls5.^ Lindberg, H. E., and Florence, A. L., Dynamic Pulse Buckling , Martinus Nijhoff Publishers, 1987, pp. 11–56, 297–298.6.Timoshenko, S. P., and Gere, J. M., Theory of Elastic Stability , 2 ed.,McGraw-Hill, 1961.■Nenezich, M., Thermoplastic Continuum Mechanics , Journal of Aerospace Structures, Vol. 4, 2004.■The Stability of Elastic Equilibrium(/DigitalCollection/1970/AFFDLTR70-025.pdf) by W. T. Koiter, PhD Thesis, 1945.■Dhakal Rajesh and Koichi Maekawa (October 2002)."Reinforcement Stability and Fracture of Cover Concrete in Reinforced Concrete Members”. [1](:8888/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JSENDH000128000010001253000001&idtype=cvips&ident=freesearch.) ■Willian T. Segui (2007). “Steel Design” Fourth Edition. United States. Chris Carson.■Analysis and design of flight vehicle structures-E.F.Brune■See alsoThe complete theory and example experimental results for long columns are available as a 39-page PDF document at /tech/buklbook.htm■/t_support/tech_pds/files/Tech%20Note-Lateral%20Torsional%20Buckling.pdf■Retrieved from "/wiki/Buckling"Categories: Elasticity (physics) | Materials science | modes Mechanical failureThis page was last modified on 6 April 2011 at 14:12.■■Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.。
专利名称:乏氧响应型比率探针合成方法及其应用专利类型:发明专利
发明人:田捷,冯欣
申请号:CN202111270243.3
申请日:20211029
公开号:CN113984729A
公开日:
20220128
专利内容由知识产权出版社提供
摘要:本发明属于生物分析领域,具体涉及了一种乏氧响应型比率探针合成方法及其应用,旨在解决现有的机体活体乏氧成像往往只能够实现定性的乏氧检测,而无法准确可靠的对乏氧程度进行评估的问题。
本发明包括:采用花青素荧光染料Cy5‑NHS修饰第五代聚酰胺‑胺树枝状大分子PAMAMG5获得PG5‑Cy5;将硝基还原酶响应型荧光分子Cy7‑NO2分子包封于PG5‑Cy5的疏水空腔,形成Cy7‑NO2/PG5‑Cy5;将肿瘤识别基团选取寡透明质酸LWHA修饰于Cy7‑NO2/PG5‑Cy5外层,合成Cy7‑NO2/PG5‑Cy5@LWHA。
本发明制备的乏氧响应型比率探针具有灵敏度高、特异性高、体内长循环的特点。
申请人:中国科学院自动化研究所
地址:100190 北京市海淀区中关村东路95号
国籍:CN
代理机构:北京市恒有知识产权代理事务所(普通合伙)
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用非均匀频率样本设计有限冲激响应数字滤波器的一种新方法戴.,JE;王龙水
【期刊名称】《雷达与对抗》
【年(卷),期】1994(000)002
【摘要】本文提出用非均匀频率样本设计FIR数字滤波器的一各新方法。
在相位上没有线性的约束。
该方法基于在复平面单位圆上牛顿多项式的内插法。
所提方法令人注目的优点是:可运用于不等间距的样本,滤波器参数的递推和半定常(Semiper-manent)的计算结果,有得到短的过渡带或锐截止频率响应的能力,以及对于实时应用高效率算法的设计。
在序列情况下,当下一个样本出现时,只要用校正项修正过去的样本来求设计参数的值,该校正项可用来作为收敛、近似值或滤波器阶减少(Re-duction)的标记。
该方法可推广到m维滤波器的设计、DFT的计算、并行算法的设计等等。
【总页数】13页(P30-42)
【作者】戴.,JE;王龙水
【作者单位】不详;不详
【正文语种】中文
【中图分类】TN713.7
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1.有限冲激响应数字滤波器的优化设计分析 [J], 臧亨
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华;刘君华
3.二阶锥规划方法对于低群延时复系数有限冲激响应数字滤波器优化设计 [J], 周青松;张剑云;李小波;刘春生
4.基于序列锥规划方法的群延时约束等纹波有限冲激响应数字滤波器优化设计 [J], 马鹏;周青松;张剑云;杨星
5.一种数字有限冲激响应滤波器电路的设计 [J], 冯晖;林争辉
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一种描述非线性动力学响应的新方法
杨永锋;任兴民;秦卫阳
【期刊名称】《中国机械工程》
【年(卷),期】2005(016)016
【摘要】针对常用非线性振动分析方法的不足,基于故障诊断理论提出了一种称为周期采样峰-峰值(PSP)图的分析方法,该方法可以有效描述非线性系统的不同类型响应,并用其研究了Duffing方程、滞后非线性汽车悬架系统和裂纹转子系统的非线性动力学响应.数值仿真结果表明,从PSP图可以明显区分响应的周期、拟周期与混沌运动,对应于周期、多倍T周期和拟周期的响应是规则的点集,而对应于混沌运动是无规则的点集.
【总页数】3页(P1468-1470)
【作者】杨永锋;任兴民;秦卫阳
【作者单位】西北工业大学,西安,710072;西北工业大学,西安,710072;西北工业大学,西安,710072
【正文语种】中文
【中图分类】O322
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2.一种储层描述新方法在渤海JX油田开发中的应用 [J], 金宝强;陈建波;杨庆红;孙
红杰
3.一种描述模糊不确定性问题的新方法 [J], 柳佳彬;左廷英
4.基于Hammerstein模型描述的非线性系统辨识新方法 [J], 向微;陈宗海
5.一种利用顶点位形描述的任意正交折线线圈阻抗解析建模新方法 [J], 吴德会;何天府;王晓红;黄一民
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3∶1内共振下超临界输液管受迫振动响应
毛晓晔;丁虎;陈立群
【期刊名称】《应用数学和力学》
【年(卷),期】2016(37)4
【摘要】首次研究了超临界流速输液管在3∶1内共振条件下的稳态幅频响应.考虑超临界速度引起的管道屈曲位形,建立描述连续体非线性振动的偏微分-积分方程.通过Galerkin截断方法,将连续体方程离散化.对于同时含有平方与立方非线性的多自由度系统,发展高阶多尺度法建立可解性条件.稳态幅频响应曲线揭示了内共振条件下,不同模态间能量的转移.最后,数值仿真结果验证了近似解析分析的有效性.【总页数】7页(P345-351)
【关键词】输液管;内共振;超临界;多尺度法;非线性
【作者】毛晓晔;丁虎;陈立群
【作者单位】上海大学上海市应用数学和力学研究所;上海大学力学系
【正文语种】中文
【中图分类】O32
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4.受迫振动的超临界输液管Galerkin数值模拟 [J], 黄慧春;张艳雷;陈立群
5.超临界输流管道3:1内共振下参激振动响应 [J], 张凯凯;谭霞;丁虎;陈立群
因版权原因,仅展示原文概要,查看原文内容请购买。