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Shift to a low carbon society through energy systems design

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Science China(Technological Sciences) 2010年第1期53卷 134-143页

作者： toshihiko nakata Mikhail RODIONOV Diego SILVA Joni JUPESTA Department of Management Science and Technology Graduate School of EngineeringTohoku UniversityAoba-yama 6-6-11-815Sendai 980-8579Japan

Concern about global warming calls for an advanced approach for designing an energy system to reduce carbon emissions as well as to secure energy security for each *** energy systems tend to introduce different technologies with high conversion efficiency,leading to a higher average *** energy systems can be achieved not by an aggregate form of conversion technologies but by an innovative system design *** concept of LCS(low carbon society) is a unique approach having multi-dimensional considerations such as social,economic and environmental *** LCS aims at an extensive restructuring of worldwide energy supply/demand network system by not only replacing the conventional parts with the new ones,but also integrating all the necessary components and designing absolutely different energy *** a core tool for the LCS design,energy-economic models are applied to show feasible solutions in future with alternatives such as renewable resources,combined heat and power,and smart grid *** can introduce changes in energy markets,technology learning in capacity,and penetration of innovative technologies,leading to an optimum system configuration under priority *** paper describes recent trials of energy models application related to waste-to-energy,clean coal,transportation and rural *** the modelling approach is still under investigation,the output clearly shows possible options having variety of technologies and linkages between supply and demand *** of the LCS means an energy systems design with the modelling approach,which gives solution for complex systems,choices among technologies,technology feasibility,R&D targets,and what we need to start.

关键词： low carbon society(LCS) energy systems systems approach clean energy technologies energy models

Rough set-based rule generation and Apriori-based rule generation from table data sets: a survey and a combination

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CAAI Transactions on Intelligence Technology 2019年第4期4卷 203-213页

作者： Hiroshi Sakai Michinori nakata Graduate School of Engineering Kyushu Institute of TechnologySensui 1-1TobataKitakyushu 804-8550Japan Faculty of Management and Information Science Josai International UniversityGumyoToganeChiba 283-0002Japan

The authors have been coping with new computational methodologies such as rough sets,information incompleteness,data mining,granular computing,etc.,and developed some software tools on association rules as well as new mathematical *** simply term this research Rough sets Non-deterministic Information Analysis(RNIA).They followed several novel types of research,especially Pawlak’s rough sets,Lipski’s incomplete information databases,Or?owska’s non-deterministic information systems,Agrawal’s Apriori *** are outstanding researches related to information incompleteness,data mining,and rule *** have been trying to combine such novel researches,and they have been trying to realise more intelligent rule generator handling data sets with information *** study surveys the authors’research highlights on rule generators,and considers a combination of them.

关键词： Apriori rule incomplete

A Fast and Memory-Efficient Direct Rendering Method for Polynomial-Based Implicit Surfaces

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Computer Modeling in Engineering & Sciences 2024年第11期141卷 1033-1046页

作者： Jiayu Ren Susumu nakata Graduate School of Information Science and Engineering Ritsumeikan UniversityIbarakiOsaka567-8570Japan2 College School of Information Science and Engineering Ritsumeikan UniversityIbarakiOsaka567-8570Japan

Three-dimensional surfaces are typically modeled as implicit ***,direct rendering of implicit surfaces is not simple,especially when such surfaces contain finely detailed *** approach is ray-casting,where the field of the implicit surface is assumed to be piecewise polynomials defined on the grid of a rectangular domain.A critical issue for direct rendering based on ray-casting is the computational cost of finding intersections between surfaces and *** particular,ray-casting requires many function evaluations along each ray,severely slowing the rendering *** this paper,a method is proposed to achieve direct rendering of polynomial-based implicit surfaces in real-time by strategically narrowing the search range and designing the shader to exploit the structure of piecewise *** experiments,the proposed method achieved a high framerate performance for different test cases,with a speed-up factor ranging from 1.1 to *** addition,the proposed method demonstrated better efficiency with high cell *** terms of memory consumption,the proposed method saved between 90.94%and 99.64%in different test ***,the proposed method became more memory-efficient as the cell resolution increased.

关键词： Implicit surfaces direct rendering ray marching

Towards tailoring basal texture of rolled Mg alloy sheet by recrystallization for high room-temperature formability: A review

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Journal of Magnesium and Alloys 2023年第11期11卷 3992-4010页

作者： T.nakata S.Kamado Nagaoka University of Technology 1603-1KamitomiokaNagaoka 940-2188Japan

Room-temperature(RT) formability is a key factor to broaden the applications of rolled Mg alloy sheets in the industry. However, rolled Mg alloy sheets generally form strong basal texture, where the(0001) poles align parallel to the normal direction(ND). This hinders the activation of(0001) [1120] basal slip, limiting the RT formability. Therefore, texture weakening, i.e., the inclination of the(0001) poles from the ND, plays an important role to improve the RT formability. Recrystallization is crucial to control the textural development in Mg,and currently, the texture weakening is commonly achieved using static recrystallization(SRX). However, the type of slipping and twinning,which are activated during rolling, affect the textural features after SRX. It is also demonstrated that shear bands and preferential grain growth are important factors to tailor the texture during SRX. Indeed, dynamic recrystallization(DRX) easily occurs during rolling in Mg, which also affects the final rolling texture, while the effect of DRX on the textural formation is not extensively studied for the development of RT-formable Mg alloy sheets. Therefore, the effect of these factors on the textural development in rolled Mg is reviewed in this ***, the ideal microstructure and texture for RT-formable Mg alloy sheets are still controversial. The RT-formability includes stretch forming(biaxial tension), bending(plane strain tension), and deep-drawing. In particular, the stretch forming is commonly used to evaluate the RT-formability of rolled Mg. Although the stretch formability has been improved by recent studies, the further improvement is necessary owing to the relatively low formability of rolled Mg compared with that of rolled Fe and Al. Based on the relationship between the microstructure/texture and stretch formability provided in the literature, the design guidance for high stretch formability is proposed in this review.

关键词： Magnesium alloy Rolling Recrystallization Texture Formability

Effects of wing deformation on aerodynamic performance of a revolving insect wing

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Acta Mechanica Sinica 2014年第6期30卷 819-827页

作者： Ryusuke Noda Toshiyuki nakata Hao Liu Graduate School of Engineering Chiba University 1-33 Yayoi-cho Inage-ku Chiba Japan Shanghai Jiao Tong University and Chiba University International Cooperative Research Center (SJTU-CUICRC) Structure and Motion Laboratory The Royal Veterinary CollegeUniversity of London Hawkshead LaneNorth Mymms Hatfield AL9 7TA United Kingdom

Flexible wings of insects and bio-inspired micro air vehicles generally deform remarkably during flapping flight owing to aerodynamic and inertial forces,which is of highly nonlinear fluid-structure interaction（FSI）*** elucidate the novel mechanisms associated with flexible wing aerodynamics in the low Reynolds number regime,we have built up a FSI model of a hawkmoth wing undergoing revolving and made an investigation on the effects of flexible wing deformation on aerodynamic performance of the revolving wing *** take into account the characteristics of flapping wing kinematics we designed a kinematic model for the revolving wing in two-fold：acceleration and steady rotation,which are based on hovering wing kinematics of hawkmoth,Manduca *** results show that both aerodynamic and inertial forces demonstrate a pronounced increase during acceleration phase,which results in a significant wing *** the aerodynamic force turns to reduce after the wing acceleration terminates due to the burst and detachment of leading-edge vortices（LEVs）,the dynamic wing deformation seem to delay the burst of LEVs and hence to augment the aerodynamic force during and even after the *** the phase of steady rotation,the flexible wing model generates more ver-tical force at higher angles of attack（40°–60°）but less horizontal force than those of a rigid wing *** is because the wing twist in spanwise owing to aerodynamic forces results in a reduction in the effective angle of attack at wing tip,which leads to enhancing the aerodynamics performance by increasing the vertical force while reducing the horizontal ***,our results point out the importance of the fluid-structure interaction in evaluating flexible wing aerodynamics：the wing deformation does play a significant role in enhancing the aerodynamic performances but works differently during acceleration and steady rotation,which is mainly induced by inertial force in accelerati

关键词： Insect flight Flexible wing Revolving wing Fluid-structure interaction

Rule induction based on rough sets from information tables having continuous domains

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CAAI Transactions on Intelligence Technology 2019年第4期4卷 237-244页

作者： Michinori nakata Hiroshi Sakai Keitarou Hara Faculty of Management and Information Science Josai International UniversityGumyoToganeChiba 283-0002Japan Graduate School of Engineering Kyushu Institute of TechnologySensui 1-1TobataKitakyushu 804-8550Japan Department of Informatics Tokyo University of Information Sciences4-1 OnaridaiWakaba-kuChiba 265-8501Japan

Information tables having continuous domains are handled by neighborhood rough *** approximations in complete information tables are extended to handle incomplete ***,four approximations are obtained:certain and possible lower ones and certain and possible upper ones without computational *** extended approximations create the same results as the ones from possible world semantics by using possible indiscernibility ***,the extension is *** complete information tables two types of single rules that an object supports are obtained:consistent and inconsistent *** single rule has low *** increase applicability,a series of single rules are brought into one combined rule with an interval *** incomplete information tables four kinds of single rules are *** them,four kinds of combined rules are obtained:certain and consistent,possible and consistent,certain and inconsistent,and possible inconsistent ones.A combined rule has higher applicability than the single rules from which it is assembled.

关键词： value. inconsistent incomplete

GLOBAL STABILITY OF SIRS EPIDEMIC MODELS WITH A CLASS OF NONLINEAR INCIDENCE RATES AND DISTRIBUTED DELAYS

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Acta Mathematica Scientia 2012年第3期32卷 851-865页

作者： Yoichi Enatsu Yukihiko nakata Yoshiaki Muroya Department of Pure and Applied Mathematics Waseda University3-4-1 OhkuboShinjuku-kuTokyo169-8555Japan Basque Center for Applied Mathematics Mazarredo14 E-48009 BilbaoSpain Department of Mathematics Waseda University 3-4-1 OhkuboShinjuku-kuTokyo 169-8555Japan

In this article, we establish the global asymptotic stability of a disease-free equilibrium and an endemic equilibrium of an SIRS epidemic model with a class of nonlin- ear incidence rates and distributed delays. By using strict monotonicity of the incidence function and constructing a Lyapunov functional, we obtain sufficient conditions under which the endemic equilibrium is globally asymptotically stable. When the nonlinear inci- dence rate is a saturated incidence rate, our result provides a new global stability condition for a small rate of immunity loss.

关键词： SIRS epidemic model nonlinear incidence rate global asymptotic stability distributed delays Lyapunov functional

Unsteady bio-fluid dynamics in flying and swimming

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Acta Mechanica Sinica 2017年第4期33卷 663-684页

作者： Hao Liu Dmitry Kolomenskiy Toshiyuki nakata Gen Li Graduate School of Engineering Chiba University 1-33Yayoi-cho Inage-ku Chiba Japan Shanghai-Jiao Tong University and Chiba UniversityInternational Cooperative Research Centre (SJTU-CU ICRC) Shanghai 200240 China

Flying and swimming in nature present sophisticated and exciting ventures in biomimetics, which seeks sustainable solutions and solves practical problems by emulating nature＇s time-tested patterns, functions, and strategies. Bio-fluids in insect and bird flight, as well as in fish swimming are highly dynamic and unsteady; however, they have been studied mostly with a focus on the phenomena associated with a body or wings moving in a steady flow. Characterized by unsteady wing flapping and body undulation, fluid-structure interactions, flexible wings and bodies, turbulent environments, and complex maneuver, bio-fluid dynamics normally have challenges associated with low Reynolds number regime and high unsteadiness in modeling and analysis of flow physics. In this article, we review and highlight recent advances in unsteady bio-fluid dynamics in terms of leading-edge vortices, passive mechanisms in flexible wings and hinges, flapping flight in unsteady environments, and micro-structured aerodynamics in flapping flight, as well as undulatory swimming, flapping-fin hydrodynamics, body–fin interac-tion, C-start and maneuvering, swimming in turbulence,collective swimming, and micro-structured hydrodynamics in swimming. We further give a perspective outlook on future challenges and tasks of several key issues of the field.

关键词： swimming wings unsteady turbulence hydrodynamics turbulent body kinematics vortex street

Interactive Restoration of Three-Dimensional Implicit Surface with Irregular Parts

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Computer Modeling in Engineering & Sciences 2023年第9期136卷 2111-2125页

作者： Jiayu Ren Yoshihisa Fujita Susumu nakata Graduate School of Information Science and Engineering Ritsumeikan UniversityShiga525-8577Japan College of Information Science and Engineering Ritsumeikan UniversityShiga525-8577Japan

Implicit surface generation based on the interpolation of surface points is one of the well-known modeling methods in the area of computer *** methods for the implicit surface reconstruction from surface points have been proposed on the basis of radial basis functions,a weighted sum of local functions,splines,wavelets,and combinations of ***,if the surface points contain errors or are sparsely distributed,irregular components,such as curvature-shaped redundant bulges and unexpectedly generated high-frequency components,are commonly *** paper presents a framework for restoring irregular components generated on and around *** are assumed to specify local masks that cover irregular components and parameters that determine the degree of *** algorithm in this paper removes the defects based on the user-specific masks and *** have shown that the proposed methods can effectively remove redundant protrusions and jaggy noise.

关键词： Shape modeling implicit surfaces interactive restoration