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AN EFFICIENT METHOD FOR MULTIOBJECTIVE OPTIMAL CONTROL AND OPTIMAL CONTROL SUBJECT TO INTEGRAL CONSTRAINTS

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Journal of Computational Mathematics 2010年第4期28卷 517-551页

作者： Ajeet Kumar alexander Vladimirsky Department of Theoretical & Applied Mechanics Cornell University Department of Mathematics Cornell University

We introduce a new and efficient numerical method for multicriterion optimal control and single criterion optimal control under integral constraints. The approach is based on extending the state space to include information on a ＂budget＂ remaining to satisfy each constraint; the augmented Hamilton-Jacobi-Bellman PDE is then solved numerically. The efficiency of our approach hinges on the causality in that PDE, i.e., the monotonicity of characteristic curves in one of the newly added dimensions. A semi-Lagrangian ＂marching＂ method is used to approximate the discontinuous viscosity solution efficiently. We compare this to a recently introduced ＂weighted sum＂ based algorithm for the same problem [25]. We illustrate our method using examples from flight path planning and robotic navigation in the presence of friendly and adversarial observers.

关键词： Optimal control Multiobjective optimization Pareto front Vector dynamic programming Hamilton-Jacobi equation Discontinuous viscosity solution Semi-Lagrangian discretization.

Completeness of citizen science biodiversity data from a volunteered geographic information perspective

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Geo-Spatial Information Science 2017年第1期20卷 3-13页

作者： Clemens Jacobs alexander Zipf GIScience Research Group Institute of GeographyHeidelberg UniversityHeidelbergGermany

Observations of living organisms by citizen scientists that are reported to online portals are a valuable source of *** are also a special kind of volunteered geographic information(VGI).VGI data have issues of completeness,which arise from biases caused by the opportunistic nature of the data collection *** examined the completeness of bird species represented in citizen science observation data from eBird and iNaturalist in US National Parks(NPs).We used approaches for completeness estimation which were developed for data from OpenStreetMap,a crowdsourced map of the ***,we used an extrinsic approach,comparing species lists from citizen science data with National Park Service ***,we examined two intrinsic approaches using total observation numbers in NPs and the development of the number of new species being added to the data-set over *** from the extrinsic approach provided appropriate completeness estimations to evaluate the intrinsic *** found that total observation numbers are a good estimator of species completeness of citizen science data from US *** is also a close relationship between species completeness and the ratio of new species added to observation data *** numbers in a given year.

关键词： Citizen science Volunteered Geographic Information(VGI) data quality completeness

Adhesion and surface forces in polymer tribology——A review

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Friction 2018年第2期6卷 143-155页

作者： Nikolai MYSHKIN alexander KOVALEV Metal-Polymer Research Institute of Belarus National Academy of Sciences State Key Laboratory of Tribology Tsinghua University

Polymer tribology is a fast growing area owing to increasing applications of polymers and polymer composites in industry, transportation, and many other areas of economy. Surface forces are very important for polymer contact, but the real origin of such forces has not been fully investigated. Strong adhesive interaction between polymers leads to an increase in the friction force, and hence, the asperities of the material may be removed to form wear particles or transfer layers on the counterface. The theory of polymer adhesion has not been completely elucidated yet and several models of adhesion have been proposed from the physical or chemical standpoints. This paper is focused on the research efforts on polymer adhesion with emphasis on adhesion mechanisms, which are very important in the analysis of polymer friction and wear.

关键词： friction dynamics joint clearance numerical models impact durability

A novel strategy of smart manipulation by micro-scale oscillatory networks of the reactionary zones for enhanced extreme thrust control of the next-generation solid propulsion systems

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Defence Technology（防务技术） 2018年第5期14卷 635-642页

作者： alexander N.Lukin Bldg.9 Tupik ZvezdniyTuapseKrasnodar TerritoryRU 352808Russian Federation

The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro-and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro-and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept,the micro-and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by selforganization of the micro-and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro-and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.

关键词： Solid propulsion systems Extreme thrust control Reactionary zones Micro-scale oscillatory networks Self-organized wave patterns Energy-releasing areas

Graded coal-its role in iron casting production from greensand systems

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China Foundry 2011年第2期8卷 235-238页

作者： alexander Brown James Durrans & Sons Ltd Phoenix WorksPenistoneSheffield S36 9QUEngland

Coal has often been regarded as a problem additive to solve and improve the surface finish of iron castings,but at the same time causes other issues such as increased loss on ignition,total fines and moisture in system *** many altermatives have been tried,there is no real substitute for thw all round properties of this wonderful natural *** the correct choice of coal,the combination of low ash,high volatile and swell index properties coupled with the key element of grading size,ensures castings are produced free from metal penetration and surface related *** careful selection,safe handling and processing coal continues to offer a good simple cost effective *** is subject to regulations in storage,processing and transportation and then further subjected to safe handling and use by the *** these handicaps,it is still economical to the end user and modern processing and grading methods ensure it is used in the optimum condition to help produce quality castings.

关键词： graded coal carbonaceous additive bentonite iron casting greensand system production

Ghosts in the shell:identification of microglia in the human central nervous system by P2Y12 receptor

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Neural Regeneration Research 2017年第4期12卷 570-571页

作者： alexander mildner max-delbrück center berlin Germany

Microglia are the tissue resident macrophages of the brain and represent the sole immune population located in the parenchyma of the central nervous system （CNS）. These cells are hidden be-tween neurons, astrocytes as well as oligodendrocytes and account for only 5-10% of CNS cells. Even though microglia were already identified in 1913 by the Spanish neuroanatomist Ramon y Cajal and further seminally investigated by his student Pio del Rio Hortega,

关键词： Ghosts in the shell identification of microglia in the human central nervous system by P2Y12 receptor

A Converse Theorem for Split SO_(2l) over Finite Fields

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Acta Mathematica Sinica,English Series 2024年第3期40卷 731-771页

作者： alexander HAZELTINE Bai Ying LIU Department of Mathematics Purdue University150 N.University St.West LafayetteIN 47907USA E-mail:ahazelti@purdue.edu liu2053@purdue.edu

We prove a converse theorem for split even special orthogonal groups over finite *** is the only case left on converse theorems of classical groups and the difficulty is the existence of the outer automorphism. In thi... 详细信息

关键词： Converse theorems generic cuspidal representations even special orthogonal groups

Review of Energy Management and Planning of Islanded Microgrids

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CSEE Journal of Power and Energy Systems 2020年第2期6卷 329-343页

作者： alexander A.Anderson Siddharth Suryanarayanan EmpowerPack SPC North BendWA 98045 USA Department of Electrical Engineering Colorado State UniversityFort CollinsCO 80523 USA

This survey paper provides a critical overview of optimization formulations for planning and operation of islanded microgrids,including optimization objectives,constraints,and control *** optimization approaches reviewed address methods both for increasing the resiliency of advanced distribution systems and electrification of remote *** paper examines over 120 individual optimization studies and discovers that all optimizations studies of islanded microgrids are based on formulations selecting a combination of 16 possible objective functions,14 constraints,and 13 control *** of the objectives,constraints,and variables are discussed exhaustively both from the perspective of their importance to islanded microgrids and chronological trends in their popularity.

关键词： Energy system planning islanded microgrids multi-objective optimization power system operation renewables forecasting

ON STABILITY BOUNDARY OF LINEAR MULTI-PARAMETER HAMILTONIAN SYSTEMS

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Acta Mechanica Sinica 2002年第6期18卷 661-670页

作者：齐朝晖 alexander P. Seyranian State Key Laboratory of Structure and Industrial Equipments Department of Engineering Mechanics Dalian University of Technology Dalian China 116023 Institute of Mechanics Moscow State Lomonosov University Moscow 117192 Russia

In this paper an approximate equation is derived to describe smooth parts of the stability boundary for linear Hamiltonian systems, depending on arbitrary number of parameters. With this equation, we can obtain parameters corresponding to the stability boundary, as well as to the stability and instability domains, provided that one point on the stability boundary is known. Then differential equations describing the evolution of eigenvalues and eigenvectors along a curve on the stability boundary surface are derived. These equations also allow us to obtain curves belonging to the stability boundary. Applications to linear gyroscopic systems are considered and studied with examples.

关键词： stability boundary Hamiltonian systems eigenvalues perturbation methods