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Model of Universe as Described by Dynamic Universe Model
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作者 Satyavarapu Naga Parameswara Gupta 《Open Journal of Modelling and Simulation》 2019年第1期41-78,共38页
In this paper we will see the model of Universe according to Dynamic Universe Model of Cosmology by visualizing various processes that are happening in the Universe as per experimental evidences. For simplifying the m... In this paper we will see the model of Universe according to Dynamic Universe Model of Cosmology by visualizing various processes that are happening in the Universe as per experimental evidences. For simplifying the matter here, we will see in part 1: about the Galaxy life cycle, where the birth and death of Galaxies discussed. Probably Universe gives guidance for the movement of Galaxies. We call this Part 1: Thinking and Reproducing Universe or Mindless Universe? (Galaxy life cycle). We see every day Sun, Stars, Galaxies etc., dissipating enormous energy in the form of radiation by the way of fusion of Hydrogen to helium. So after sometime all the Hydrogen is spent and Universe will die, is it not? … Dynamic Universe Model says that the energy in the form of electromagnetic radiation passing grazingly near any gravitating mass changes in frequency and finally will convert into neutrinos (mass). Hence Dynamic Universe Model proposes another process where energy will be converted back into matter and the cycle energy to mass to energy continues, sustaining the Universe to maintain this present status for ever in this form something like a Steady state model without any expansion. This we will see in Part 2: Energy - Mass - Energy Cycle. After converting energy into mass “how various elements are formed and where they are formed?” will be next logical question. Dynamic Universe Model says that these various particles change into higher massive particles or may get bombarded into stars or planets and various elements are formed. Here we bifurcate the formation of elements into 6 processes. They are for Elementary particles and elements generated in frequency changing process, By Cosmic rays, By Small stars, By Large Stars, By Super Novae and Manmade elements By Neutron Stars. This we will discuss in Part 3: Nucleosynthesis. 展开更多
关键词 dynamic UNIVERSE MODEL Hubble Space Telescope (HST) SITA Simulations (SITA-Simulation of Inter Intra Tautness Attraction Forces Used by dynamic UNIVERSE Model) Singularity-Free COSMOLOGY Blue Shifted GALAXIES Red Shifted GALAXIES Grazing Radiation Frequency Changes Formation of Elements Nucleosynthesis dynamic UNIVERSE MODEL Energy to Mass Conversion Methods: N-Body Simulations-Gravitation-Cosmology
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Nonlinear Differential Equation of Macroeconomic Dynamics for Long-Term Forecasting of Economic Development
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作者 Askar Akaev 《Applied Mathematics》 2018年第5期512-535,共24页
In this article we derive a general differential equation that describes long-term economic growth in terms of cyclical and trend components. Equation is based on the model of non-linear accelerator of induced investm... In this article we derive a general differential equation that describes long-term economic growth in terms of cyclical and trend components. Equation is based on the model of non-linear accelerator of induced investment. A scheme is proposed for obtaining approximate solutions of nonlinear differential equation by splitting solution into the rapidly oscillating business cycles and slowly varying trend using Krylov-Bogoliubov-Mitropolsky averaging. Simplest modes of the economic system are described. Characteristics of the bifurcation point are found and bifurcation phenomenon is interpreted as loss of stability making the economic system available to structural change and accepting innovations. System being in a nonequilibrium state has a dynamics with self-sustained undamped oscillations. The model is verified with economic development of the US during the fifth Kondratieff cycle (1982-2010). Model adequately describes real process of economic growth in both quantitative and qualitative aspects. It is one of major results that the model gives a rough estimation of critical points of system stability loss and falling into a crisis recession. The model is used to forecast the macroeconomic dynamics of the US during the sixth Kondratieff cycle (2018-2050). For this forecast we use fixed production capital functional dependence on a long-term Kondratieff cycle and medium-term Juglar and Kuznets cycles. More accurate estimations of the time of crisis and recession are based on the model of accelerating log-periodic oscillations. The explosive growth of the prices of highly liquid commodities such as gold and oil is taken as real predictors of the global financial crisis. The second wave of crisis is expected to come in June 2011. 展开更多
关键词 Long-Term Economic Trend Cycles Nonlinear Accelerator Induced and Autonomous Investment Differential Equations of MACROECONOMIC dynamics Bifurcation Stability CRISIS RECESSION Forecasting Explosive Growth in the PRICES of Highly Liquid Commodities as a PREDICTOR of CRISIS
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Novel disturbance compensating dynamic positioning of dredgers based on adaptive backstepping 被引量:1
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作者 张宇华 姜建国 郜登科 《Journal of Southeast University(English Edition)》 EI CAS 2011年第1期36-39,共4页
In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and... In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and compensated for by the adaptive method without extra sensors on dredging equipment,and the control mechanism is simplified.Adaptive control is used to compensate for the reaction and environmental disturbances on the dredger,so the dredger can maintain the desired position with a minimum error and shock.The proposed adaptive robust controller guarantees the global asymptotic stability of the closed-loop system and rapid position tracking of the dredger.The simulation results show that the proposed controller has superior performance in position tracking and robustness to large disturbances. 展开更多
关键词 dynamic positioning(DP) adaptive backstepping nonlinear control DREDGER disturbance compensating
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Design and Reliability Analysis of DP-3 Dynamic Positioning Control Architecture 被引量:4
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作者 王芳 万磊 +1 位作者 姜大鹏 徐玉如 《China Ocean Engineering》 SCIE EI 2011年第4期709-720,共12页
As the exploration and exploitation of oil and gas proliferate throughout deepwater area, the requirements on the reliability of dynamic positioning system become increasingly stringent. The control objective ensuring... As the exploration and exploitation of oil and gas proliferate throughout deepwater area, the requirements on the reliability of dynamic positioning system become increasingly stringent. The control objective ensuring safety operation at deep water will not be met by a single controller for dynamic positioning. In order to increase the availability and reliability of dynamic positioning control system, the triple redundancy hardware and software control architectures were designed and developed according to the safe specifications of DP-3 classification notation for dynamically positioned ships and rigs. The hardware redundant configuration takes the form of triple-redundant hot standby configuration including three identical operator stations and three real-time control computers which connect each other through dual networks. The function of motion control and redundancy management of control computers were implemented by software on the real-time operating system VxWorks. The software realization of task loose synchronization, majority voting and fault detection were presented in details. A hierarchical software architecture was planed during the development of software, consisting of application layer, real-time layer and physical layer. The behavior of the DP-3 dynamic positioning control system was modeled by a Markov model to analyze its reliability. The effects of variation in parameters on the reliability measures were investigated. The time domain dynamic simulation was carried out on a deepwater drilling rig to prove the feasibility of the proposed control architecture 展开更多
关键词 DP-3 dynamic positioning system reliability triple redundancy motion control redundancy management
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Simplified Coarse-Grained Dynamic Model for Real Gases
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作者 Panagis G. Papadopoulos Christopher G. Koutitas +1 位作者 Yannis N. Dimitropoulos Elias C. Aifantis 《Open Journal of Physical Chemistry》 2017年第2期50-71,共22页
A simplified model is proposed for an easy understanding of the coarse-grained technique and for achieving a first approximation to the behavior of gases. A mole of a gas substance, within a cubic container, is repres... A simplified model is proposed for an easy understanding of the coarse-grained technique and for achieving a first approximation to the behavior of gases. A mole of a gas substance, within a cubic container, is represented by six particles symmetrically moving. The impacts of particles on container walls, the inter-particle collisions, as well as the volume of particles and the inter-particle attractive forces, obeying a Lennard-Jones curve, are taken into account. Thanks to the symmetry, the problem is reduced to the nonlinear dynamic analysis of a SDOF oscillator, which is numerically solved by a step-by-step time integration algorithm. Five applications of proposed model, on Carbon Dioxide, are presented: 1) Ideal gas in STP conditions. 2) Real gas in STP conditions. 3) Condensation for small molar volume. 4) Critical point. 5) Iso-kinetic energy curves and iso-therms in the critical point region. Results of the proposed model are compared with test data and results of the Van der Waals model for real gases. 展开更多
关键词 Real Gases COARSE-GRAINED Molecular dynamics Particles Volume Inter-Particle ATTRACTIVE Forces LENNARD-JONES Curve STEP-BY-STEP Time Integration Algorithm Condensation Critical Point Iso-Kinetic Energy Curves Iso-Therms Van der WAALS Model
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Virtual Reality Simulation of Fuzzy-logic Control during Underwater Dynamic Positioning 被引量:4
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作者 Midhin Das Thekkedan Cheng Siong Chin Wai Lok Woo 《Journal of Marine Science and Application》 CSCD 2015年第1期14-24,共11页
In this paper, graphical-user-interface (GUI) software for simulation and fuzzy-logic control of a remotely operated vehicle (ROV) using MATLABTM GUI Designing Environment is proposed. The proposed ROV's GUI plat... In this paper, graphical-user-interface (GUI) software for simulation and fuzzy-logic control of a remotely operated vehicle (ROV) using MATLABTM GUI Designing Environment is proposed. The proposed ROV's GUI platform allows the controller such as fuzzy-logic control systems design to be compared with other controllers such as proportional-integral-derivative (PID) and sliding-mode controller (SMC) systematically and interactively. External disturbance such as sea current can he added to improve the modelling in actual underwater environment. The simulated results showed the position responses of the fuzzy-logic control exhibit reasonable performance under the sea current disturbance. 展开更多
关键词 graphical-user-interface GUI fuzzy-logic control remotely operated vehicle ROV proportional-integral-derivative PID sliding-mode controller SMC underwater dynamic positioning
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Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials
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作者 Hong Shih 《Materials Sciences and Applications》 2019年第3期253-292,共40页
In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arre... In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general. 展开更多
关键词 Aluminum Spherical Power GAS FLUIDIZATION Bed Oxidation Mechanism Oxide Growth Rate Gibbs Free Energy Ellingham Diagram Mathematical Modeling dynamic System Plasma DIFFUSION DIFFUSION Coefficient Crystallographic Defect Vacancy Pressure Temperature Flow Laplace Transform Equation Boundary Condition Ficks Second Law Software Experimental Theoretical SURGE ARRESTING MATERIALS Analytical Solution
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Dynamic Positioning System Design for A Marine Vessel with Unknown Dynamics Subject to External Disturbances Including Wave Effect
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作者 Alireza HOSSEINNAJAD Mehdi LOUEIPOUR 《China Ocean Engineering》 SCIE EI CSCD 2020年第5期651-663,共13页
In this paper, a new control system is proposed for dynamic positioning(DP) of marine vessels with unknown dynamics and subject to external disturbances. The control system is composed of a substructure for wave filte... In this paper, a new control system is proposed for dynamic positioning(DP) of marine vessels with unknown dynamics and subject to external disturbances. The control system is composed of a substructure for wave filtering and state estimation together with a nonlinear PD-type controller. For wave filtering and state estimation, a cascade combination of a modified notch filter and an estimation stage is considered. In estimation stage, a modified extended-state observer(ESO) is proposed to estimate vessel velocities and unknown dynamics. The main advantage of the proposed method is its robustness to model uncertainties and external disturbances and it does not require prior knowledge of vessel model parameters. Besides, the stability of the cascade structure is analyzed and input to state stability(ISS) is guaranteed. Later on, a nonlinear PD-type controller with feedforward of filtered estimated dynamics is utilized. Detailed stability analyses are presented for the closed-loop DP control system and global uniform ultimate boundedness is proved using large scale systems method. Simulations are conducted to evaluate the performance of the proposed method for wave filtering and state estimation and comparisons are made with two conventional methods in terms of estimation accuracy and the presence of uncertainties. Besides, comparisons are made in closed-loop control system to demonstrate the performance of the proposed method compared with conventional methods. The proposed control system results in better performance in the presence of uncertainties,external disturbance and even in transients when the vessel is subjected to sudden changes in environmental disturbances. 展开更多
关键词 dynamic positioning environmental disturbances marine vessel state estimation unknown dynamics wave filtering
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Fixed Time Control of Dynamic Positioning Ship with Unknown Interference
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作者 Peng Xu 《Open Journal of Applied Sciences》 2020年第5期246-257,共12页
This paper proposes a fixed-time control scheme to ensure that the dynamic positioning can accurately reach the specified position under external interference. A fixed-time state observer was developed to accurately e... This paper proposes a fixed-time control scheme to ensure that the dynamic positioning can accurately reach the specified position under external interference. A fixed-time state observer was developed to accurately estimate the total external unknown interference. Based on the dynamic positioning ship motion model, the inversion design method is used to ensure the stability of the system and eliminate various uncertain effects. A fixed-time backstepping sliding mode controller is designed. Finally, the simulation results show that the method has good performance and advantages. 展开更多
关键词 dynamic positioning Fixed-Time OBSERVER SLIDING Mode CONTROL
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Dynamic NMR and Twisted Intramolecular Charge Transfer Excited States
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作者 Iraj Parchamazad Debra Hornyak Melvin Miles 《American Journal of Analytical Chemistry》 2015年第5期402-410,共9页
In this paper the results of dynamic NMR studies on ethylmethylamino-tertiary-butyl-phenylborane (EMABPB) with or without light are reported. The NMR data were recorded on a Bruker 400 MHz NMR equipped with our custom... In this paper the results of dynamic NMR studies on ethylmethylamino-tertiary-butyl-phenylborane (EMABPB) with or without light are reported. The NMR data were recorded on a Bruker 400 MHz NMR equipped with our custom-made optical probe and with our custom-made 450 watts (W) monochromatic light sources. The molecular photochemistry including twisted intramolecular charge-transfer-excited-state (TICT) of the EMABPB in several solvents has been investigated. These results indicate that the aminoborane demonstrates multiple configurations in CD3Cl and CD2Cl2 resulting in the shifts of the signals of the alkyl groups on the nitrogen and boron. This indicates that there are some time-dependent changes at constant temperature over the irradiation interval. At ﹣60&deg;C and the presence of light (λ = 265 nm), we observed a large change in the populations of the two sites, and this by itself indicates a modification in the rotation around the boron nitrogen bond in the excited state. By considering the existence of the TICT state, many important energy technologies may be developed with higher efficiency by controlling the back-electron transfer processes. 展开更多
关键词 TWISTED Intramolecular Charge TRANSFER STATE Back Electron TRANSFER TWISTED Excited STATE dynamic NMR Rotation around B-N Bond Molecular PHOTOCHEMISTRY inside NMR PROBE Customized Optical PROBE Solvent Effect Low Temperature Spectra
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Model Predictive Controller Design for the Dynamic Positioning System of a Semi-submersible Platform 被引量:3
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作者 Hongli Chen Lei Wan Fang Wang Guocheng Zhang 《Journal of Marine Science and Application》 2012年第3期361-367,共7页
This paper researches how to apply the advanced control technology of model predictive control (MPC) to the design of the dynamic positioning system (DPS) of a semi-submersible platform. First, a linear low-freque... This paper researches how to apply the advanced control technology of model predictive control (MPC) to the design of the dynamic positioning system (DPS) of a semi-submersible platform. First, a linear low-frequency motion model with three degrees of freedom was established in the context of a semi-submersible platform. Second, a model predictive controller was designed based on a model which took the constraints of the system into account. Third, simulation was carried out to demonstrate the feasibility of the controller. The results show that the model predictive controller has good performance and good at dealing with the constraints or the system. 展开更多
关键词 dynamic positioning system model predictive controller constraints handling semi-submersibleplatform low-frequency motion model
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Positioning in Dynamic Testing of Slender Bridges
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作者 Alexander Tesar Jan Bencat 《Positioning》 2011年第3期103-111,共9页
The positioning combined with multi-functioning and interactive mechanics in dynamic testing of slender bridges are treated in present paper. The approach takes into account multiple functions in dynamic testing of sl... The positioning combined with multi-functioning and interactive mechanics in dynamic testing of slender bridges are treated in present paper. The approach takes into account multiple functions in dynamic testing of slender bridges constructed of thin-walled structural members with their hierarchical configuration. Theoretical, numerical and experimental in situ assessments of the problem are presented. Some results of the application in situ are submitted. 展开更多
关键词 BRIDGES Deformation positioning dynamic Testing Interactive MECHANICS FOURIER Transformation Mul-ti-functioning Optimization Virtual Monitoring Wave Propagation
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Fully Coupled Time-Domain Simulation of Dynamic Positioning Semi-Submersible Platform Using Dynamic Surface Control 被引量:1
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作者 LIANG Haizhi LI Luyu OU Jinping 《Journal of Ocean University of China》 SCIE CAS 2014年第3期407-414,共8页
A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force d... A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning(DP) system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control(DSC) is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function(RBF) neural networks(NNs) can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers' wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN centers are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed control strategy. 展开更多
关键词 dynamic positioning system coupled analysis dynamic surface control RBF NNs adaptive control
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Means of Choice for Interactive Management of Dynamic Geometry Problems Based on Instrumented Behaviour
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作者 Philippe R. Richard Michel Gagnon +2 位作者 Josep Maria Fortuny Nicolas Leduc Michèle Tessier-Baillargeon 《American Journal of Computational Mathematics》 2013年第3期41-51,共11页
Our paper presents a project that involves two research questions: does the choice of a related problem by the tutorial system allow the problem solving process which is blocked for the student to be restarted? What i... Our paper presents a project that involves two research questions: does the choice of a related problem by the tutorial system allow the problem solving process which is blocked for the student to be restarted? What information about learning do related problems returned by the system provide us? We answer the first question according to the didactic engineering, whose mode of validation is internal and based on the confrontation between an a priori analysis and an a posteriori analysis that relies on data from experiments in schools. We consider the student as a subject whose adaptation processes are conditioned by the problem and the possible interactions with the computer environment, and also by his knowledge, usually implicit, of the institutional norms that condition his relationship with geometry. Choosing a set of good problems within the system is therefore an essential element of the learning model. Since the source of a problem depends on the student’s actions with the computer tool, it is necessary to wait and see what are the related to problems that are returned to him before being able to identify patterns and assess the learning. With the simultaneity of collecting and analysing interactions in each class, we answer the second question according to a grounded theory analysis. By approaching the problems posed by the system and the designs in play at learning blockages, our analysis links the characteristics of problems to the design components in order to theorize on the decisional, epistemological, representational, didactic and instrumental aspects of the subject-milieu system in interaction. 展开更多
关键词 DIDACTICS of Mathematics Competencies Geometric Thinking TUTORIAL System Related PROBLEMS dynamic Geometry Instrumented Behavior Cognitive Interactions CONCEPTIONS Mathematical Work Space MEANS of CHOICE Didactic Contract
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Dispersion Dynamical Magnetic Radius in Intrinsic Spin Equals the Compton Wavelength
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作者 Antony J. Bourdillon 《Journal of Modern Physics》 2018年第13期2295-2307,共13页
Because magnetic moment is spatial in classical magnetostatics, we progress beyond the axiomatic concept of the point particle electron in physics. Orbital magnetic moment is well grounded in spherical harmonics in a ... Because magnetic moment is spatial in classical magnetostatics, we progress beyond the axiomatic concept of the point particle electron in physics. Orbital magnetic moment is well grounded in spherical harmonics in a central field. There, quantum numbers are integral. The half-integral spinor moment appears to be due to cylindrical motion in an external applied magnetic field;when this is zero , the spin states are degenerate. Consider lifting the degeneracy by diamagnetism in the cylindrical magnetic field: a uniquely derived electronic magnetic radius shares the identical value to the Compton wavelength. 展开更多
关键词 Magnetic RADIUS INTRINSIC SPIN COMPTON WAVELENGTH DISPERSION dynamics Stable Wave Packet Special Relativity Propagation Transverse Plane Functions of Relativistic Free Particles Quantum Physics Quantum Mechanics
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Robustifying Dynamic Positioning of Crane Vessels for Heavy Lifting Operation
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作者 Jun Ye Spandan Roy +2 位作者 Milinko Godjevac Vasso Reppa Simone Baldi 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2021年第4期753-765,共13页
Construction crane vessels make use of dynamic positioning(DP)systems during the installation and removal of offshore structures to maintain the vessel’s position.Studies have reported cases of instability of DP syst... Construction crane vessels make use of dynamic positioning(DP)systems during the installation and removal of offshore structures to maintain the vessel’s position.Studies have reported cases of instability of DP systems during offshore operation caused by uncertainties,such as mooring forces.DP"robustification"for heavy lift operations,i.e.,handling such uncertainties systematically and with stability guarantees,is a long-standing challenge in DP design.A new DP method,composed by an observer and a controller,is proposed to address this challenge,with stability guarantees in the presence of uncertainties.We test the proposed method on an integrated cranevessel simulation environment,where the integration of several subsystems(winch dynamics,crane forces,thruster dynamics,fuel injection system etc.)allow a realistic validation under a wide set of uncertainties. 展开更多
关键词 Construction crane vessels dynamic positioning system OFFSHORE robust control UNCERTAINTY
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晚粳稻籽粒中砷、镉、铬、镍、铅等重金属含量的品种和粒位效应 被引量:40
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作者 程旺大 张国平 +2 位作者 姚海根 Peter DOMINY 王润屹 《中国水稻科学》 CAS CSCD 北大核心 2005年第3期273-279,共7页
选用籽粒着粒密度差异较大的密穗型品种秀水63和散穗型品种秀水11,种植于受重金属轻度污染的土壤,研究了晚粳稻籽粒中有毒重金属As、Cd、Cr、Ni、Pb含量的品种与粒位效应。结果表明,重金属含量的粒位间差异秀水63明显大于秀水11,As、Cd... 选用籽粒着粒密度差异较大的密穗型品种秀水63和散穗型品种秀水11,种植于受重金属轻度污染的土壤,研究了晚粳稻籽粒中有毒重金属As、Cd、Cr、Ni、Pb含量的品种与粒位效应。结果表明,重金属含量的粒位间差异秀水63明显大于秀水11,As、Cd、Cr、Pb含量粒位间差异显著,Ni含量差异较小。穗上部籽粒As、Cd、Ni含量高于中部籽粒,穗下部籽粒最低,而Cr、Pb则正好相反。稻米中几种重金属含量与粒重的关系因重金属种类不同存在着差异,籽粒As、Cd、Ni含量与粒重呈正相关,而Cr和Pb含量与粒重呈负相关。秀水63和秀水11不同粒位的籽粒灌浆模式存在差异,下位粒灌浆速率较低,使粒重较上、中位粒低,导致粒重有较大的粒位差异,而这种差异也与穗部着粒密度有关,秀水63明显大于秀水11。籽粒As、Cd、Ni含量与最大灌浆速率(GRm)呈正相关,与到达最大灌浆速率时间(Tpoi)呈负相关,而Cr和Pb含量与以上两个籽粒灌浆特性参数分别呈负相关和正相关,说明籽粒As、Cd、Ni的积累与碳水化合物的积累具有相同或相近的模式,而Cr和Pb表现为不同的积累模式。 展开更多
关键词 As Cd Cr Ni Pb
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Global Robust and Adaptive Output Feedback Dynamic Positioning of Surface Ships 被引量:10
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作者 Khac Duc Do 《Journal of Marine Science and Application》 2011年第3期325-332,共8页
A constructive method was presented to design a global robust and adaptive output feedback controller for dynamic positioning of surface ships under environmental disturbances induced by waves, wind, and ocean current... A constructive method was presented to design a global robust and adaptive output feedback controller for dynamic positioning of surface ships under environmental disturbances induced by waves, wind, and ocean currents. The ship's parameters were not required to be known. An adaptive observer was first designed to estimate the ship's velocities and parameters. The ship position measurements were also passed through the adaptive observer to reduce high frequency measurement noise from entering the control system. Using these estimate signals, the control was then designed based on Lyapunov's direct method to force the ship's position and orientation to globally asymptotically converge to desired values. Simulation results illustrate the effectiveness of the proposed control system. In conclusion, the paper presented a new method to design an effective control system for dynamic positioning of surface ships. 展开更多
关键词 dynamic positioning surface vessel robust and adaptive output feedback nonlinear control
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Portable Dynamic Positioning Control System on A Barge in Short-Crested Waves Using the Neural Network Algorithm 被引量:2
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作者 FANG Ming-chung LEE Zi-yi 《China Ocean Engineering》 SCIE EI CSCD 2013年第4期469-480,共12页
This paper develops a nonlinear mathematical model to simulate the dynamic motion behavior of the barge equipped with the portable outboard Dynamic Positioning (DP) system in short-crested waves. The self-tuning Pro... This paper develops a nonlinear mathematical model to simulate the dynamic motion behavior of the barge equipped with the portable outboard Dynamic Positioning (DP) system in short-crested waves. The self-tuning Proportional- Derivative (PD) controller based on the neural network algorithm is applied to control the thrusters for optimal adjustment of the barge position in waves. In addition to the wave, the current, the wind and the nonlinear drift force are also considered in the calculations. The time domain simulations for the six-degree-of-freedom motions of the barge with the DP system are solved by the 4th order Runge-Kutta method which can compromise the efficiency and the accuracy of the simulations. The technique of the portable alternative DP system developed here can serve as a practical tool to assist those ships without being equipped with the DP facility while the dynamic positioning missions are needed. 展开更多
关键词 neural network PD controller dynamic positioning short-crested wave
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Nonlinear observer-controller design for dynamic positioning of ships 被引量:2
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作者 何黎明 田作华 施颂椒 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2004年第3期359-363,共5页
The main focus is nonlinear model-based dynamic positioning (DP) control system design. A nonlinear uniform global exponential stability (UGES) observer produces noise-free estimates of the position, the slowly varyin... The main focus is nonlinear model-based dynamic positioning (DP) control system design. A nonlinear uniform global exponential stability (UGES) observer produces noise-free estimates of the position, the slowly varying environmental disturbances and the velocity, which are used in a proportional-derivative (PD) + feedforward control law. The stability of this observer-controller system is proved by introducing a specific nonlinear cascaded system. The simulation results have successfully demonstrated the performance of designed DP control system. 展开更多
关键词 dynamic positioning nonlinear observer nonlinear PD %PLUS% feedforward control stability analysis.
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