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Modeling the dynamics of innovation ecosystems

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International Journal of Innovation Studies 2023年第2期7卷 142-158页

作者： jaakko Paasi Henri Wiman Tina Apilo Katri Valkokari VTT Technical Research Centre of Finland Ltd. P.O.Box 1000FI-02044VTTFinland

Demand for solving systemic problems has resulted in the need for new forms of ***,the concept of innovation ecosystem has *** are intrinsically more fluid than networks,which set ups the need to understand and orchestrate the internal dynamics of innovation ecosystem in order to have successful innovation *** dynamics of ecosystems,however,is not well *** this paper the dynamics of innovation ecosystems has been studied by applying the methodology of system *** purpose of the study is to support the creation of innovation ecosystems and the orchestration of existing ecosystems so that they could be more *** factors generating dynamics in innovation ecosystems were *** form the elements of the system dynamics model of innovation *** causal loop structure between the model elements indicates how the key factors of dynamics influence the outcome of ecosystem.

关键词： Ecosystem Innovationecosystem Open innovation Systemdynamics Modeling

Radial Forces in a Centrifugal Compressor; Experimental Investigation by Using Magnetic Bearings and Static Pressure Distribution

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Journal of Thermal Science 2005年第1期14卷 1-8页

作者： Arttu REUNANEN jaakko LARJOLA Department of Energy and Environmental Technology Lappeenranta University of Technology LappeenrantaFinlandDepartment of Energy and Environmental Technology Lappeenranta University of TechnologyLappeenrantaFinland

The volute of a centrifugal compressor causes a non-uniform pressure distribution which leads to a radial force on the impeller. This force was measured using magnetic bearings. In addition, the radial force was estimated using the static pressure distribution measured at the impeller outlet. The impeller force was found to be the highest at choke, the lowest at the design flow and moderate at stall. The radial force determined from the pressure measurements was only slightly different from the force obtained from the bearing measurements. The rotational speed was seen to affect the force to some extent.

关键词：离心压气机径向力实验观测静态压力分布磁性轴承

Unsteady Pressure Field in a Vaneless Diffuser of a Centrifugal Compressor: An Experimental and Computational Analysis

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Journal of Thermal Science 2004年第4期13卷 302-309页

作者： Teemu TURUNEN-SAARESTI jaakko LARJOLA Lappeenranta University of Technology Laboratory of Fluid Dynamics P.O. Box 20 53851 Lappeenranta FinlandLappeenranta University of Technology Laboratory of Fluid Dynamics P.O. Box 20 53851 Lappeenranta Finland

Unsteady static pressure was measured and time-accurate numerical simulations were conducted in order to analyze unsteady behaviour of the centrifugal compressor diffuser. The unsteady static pressure was measured at the diffuser inlet and outlet at three different circumferential positions. Operation points near the surge, the design operation point and operation point near the choke were used in measurements. The time-accurate simulations were conducted at the design operation point and operation point near the choke. The whole compressor was modelled and the low Reynolds number k-εturbulence model was utilized in numerical simulations. The gathered numerical and experimental unsteady pressures were compared with each other.

关键词： centrifugal compressor vaneless diffuser unsteady pressure.

Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings

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Journal of Materials Science & Technology 2022年第5期100卷 91-100页

作者： Nikolaus Jager Michael Meindlhumer Michal Zitek Stefan Spor Hynek Hruby Farwah Nahif jaakko Julin Martin Rosenthal Jozef Keckes Christian Mitterer Rostislav Daniel Christian Doppler Laboratory for Advanced Synthesis of Novel Multifunctional Coatings at the Department of Materials Science Montanuniversität LeobenAustria voestalpine eifeler Vacotec GmbH DüsseldorfGermany Institute of Ion Beam Physics and Materials Research Helmholtz-Zentrum Dresden-RossendorfDresdenGermany Department of Physics University of JyvaskylaFinland European Synchrotron Radiation Facility GrenobleFrance Erich Schmid Institute for Materials Science Austrian Academy of SciencesAustria Department of Materials Science Montanuniversität LeobenAustria

The resistance of wear protective coatings against oxidation is crucial for their use at high ***,three nanocomposite AlCr(Si)N coatings with a fixed Al/Cr atomic ratio of 70/30 and a varying Si-content of 0 at.%,2.5 at.% and 5 at.% were analyzed by differential scanning calorimetry,thermogravimetric analysis and X-ray in order to understand the oxidation behavior depending on their ***,a partially oxidized AlCrSiN coating with 5 at.%Si on a sapphire substrate was studied across the coating thickness by depth-resolved cross-sectional X-ray nanodiffraction and scanning trans-mission electron microscopy to investigate the elemental composition,morphology,phases and residual stress evolution of the oxide scale and the non-oxidized coating *** results reveal enhanced oxidation properties of the AlCr(Si)N coatings with increasing Si-content,as demonstrated by a retarded onset of oxidation to higher temperatures from 1100℃ for AlCrN to 1260℃ for the Si-containing coatings and a simultaneous deceleration of the oxidation *** annealing of the AlCrSiN sample with5 at.%Si at an extraordinary high temperature of 1400℃ for 60 min in ambient air,three zones developed throughout the coating strongly differing in their composition and structure:(i)a dense oxide layer comprising an Al-rich and a Cr-rich zone formed at the very top,followed by(ii)a fine-grained transition zone with incomplete oxidation and(iii)a non-oxidized zone with a porous *** varying elemental composition of these zones is furthermore accompanied by micro-structural variations and a complex residual stress development revealed by cross-sectional X-ray *** results provide a deeper understanding of the oxidation behavior of AlCr(Si)N coatings depending on their Si-content and the associated elemental,microstructural and residual stress evolution during high-temperature oxidation.

关键词： AlCrSiN Nanocomposite Cathodic arc Oxidation behaviour Cross-sectional X-ray nanodiffraction

Numerical and Experimental Modelling of Gas Flow and Heat Transfer in the Air Gap of an Electric Machine

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Journal of Thermal Science 2004年第3期13卷 264-278页

作者： Maunu KUOSA Petri SALLINEN jaakko LARJOLA Lappeenranta University of Technology (LUT) Department of Energy and Environmental Technology P.O. Box 20 53851 Lappeenranta FinlandLappeenranta University of Technology (LUT) Department of Energy and Environmental Technology P.O. Box 20 53851 Lappeenranta FinlandLappeenranta University of Technology (LUT) Department of Energy and Environmental Technology P.O. Box 20 53851 Lappeenranta Finland

This work deals with the cooling of high-speed electric machines, such as motors and generators, through an air gap. It consists of numerical and experimental modeling of gas flow and heat transfer in an annular channel. Velocity and temperature profiles are modeled in the air gap of a high-speed test machine. Friction and heat transfer coefficients are presented in a large velocity range. The goals are reached acceptably using numerical and experimental research. The velocity field by the numerical method does not match in every respect the estimated flow mode. The absence of secondary Taylor vortices is evident when using time averaged numerical simulation.

关键词： heat transfer electric machine air gap friction coefficient CFD.

THE EFFECT OF WORKER LEARNING ON SCHEDULING JOBS IN A HYBRID FLOW SHOP： A BI-OBJECTIVE APPROACH

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Journal of Systems Science and Systems Engineering 2018年第3期27卷 265-291页

作者： Farzad Pargar Mostafa Zandieh Osmo Kauppila jaakko Kujala Industrial Engineering and Management Faculty of Technology University ofOulu Oulu Finland Department of Industrial Management Management and Accounting Faculty Shahid Beheshti University G.C.Tehran Iran

This paper studies learning effect as a resource utilization technique that can model improvement in worker＇s ability as a result of repeating similar tasks. By considering learning of workers while performing setup times, a schedule can be determined to place jobs that share similar tools and fixtures next to each other. The purpose of this paper is to schedule a set of jobs in a hybrid flow shop （HFS） environment with learning effect while minimizing two objectives that are in conflict： namely maximum completion time （makespan） and total tardiness. Minimizing makespan is desirable from an internal efficiency viewpoint, but may result in individual jobs being scheduled past their due date, causing customer dissatisfaction and penalty costs. A bi-objective mixed integer programming model is developed, and the complexity of the developed bi-objective model is compared against the bi-criteria one through numerical examples. The effect of worker learning on the structure of assigned jobs to machines and their sequences is analyzed. Two solution methods based on the hybrid water flow like algorithm and non-dominated sorting and ranking concepts are proposed to solve the problem. The quality of the approximated sets of Pareto solutions is evaluated using several performance criteria. The results show that the proposed algorithms with learning effect perform well in reducing setup times and eliminate the need for setups itself through proper scheduling.

关键词： Bi-objective scheduling hybrid flow shop learning effect meta-heuristic

Fluid dynamic modeling of a free piston engine with labyrinth seals

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Journal of Thermal Science 2010年第2期19卷 141-147页

作者： jaakko Larjola Juha Honkatukia Petri Sallinen Jari Backman Lappeenranta University of Technology P.O.Box 2053851 Lappeenranta

Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this *** properties,particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case,and the results are utilized in preliminary main design parameter *** engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology,Tampere University of Technology,and Lappeenranta University of *** of the contact-free labyrinth seal used in the piston,the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston *** the other hand,the lack of bearing losses,and the lack of losses associated with a crankshaft system and a gearbox,as well as the lack of lubrication oil expenses,compensates this *** a net result,this new motor would perform slightly better than the conventional *** completely oil-free,it is very environmentally friendly,and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.

关键词：自由活塞发动机迷宫密封流体动力学模型分布式能源系统模拟仿真密封性能设计参数程序开发

Philosophical Research and General Education

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Frontiers of Philosophy in China 2013年第2期8卷 240-246页

作者： jaakko Hintikka Department of Philosophy Boston University Boston MA 02215 USA

What can philosophical research do today to improve the lot of contemporary societies globally？ What can anyone do for the purpose？ To take the most urgent international problems as an example, what kind of person should the Secretary-General of the UN send to disarm a conflict situation？ Perhaps a religious leader, a priest, an imam or a guru？ But a leader of which religion？ Perhaps a lawyer？ But a lawyer is by definition some particular client＇s advocate. I submit that the best background of such a negotiator would be that of a labor arbitrator. Such a professional is trained to take into account the interest of different and conflicting parties. The success of a persuasive arbitrator presupposes a capacity to analyze objectively and realistically not only the professed goals of different parties, but the actual consequences of the realization of those goals. It presupposes objective knowledge of the consequences of different courses of action and the ability to explain them to the different parties. Above all, it presupposes a skill in finding possibilities of synthesizing apparently conflicting points of view.

关键词： Deductive reasoning Critical thinking Mathematical logic Thinking skills Epistemology Inference Mathematics Educational philosophies

Optimization of the Mean Radius Flow Path of a Multi-Stage Steam Turbine with Evolution Algorithms

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Journal of Thermal Science 2011年第4期20卷 318-323页

作者： Jukka Huttunen jaakko Larjola Teemu Turunen-Saaresti Jari Backman Savonia Power ljytie 678710 VarkausFinlandjukka Lappeenranta University of Technology P.O.Box 2053851 LappeenrantaFinland

A prototype model of the mean radius flow path of a four-stage,high speed 1 MWe axial steam turbine was optimized by using evolution algorithms,DE(differential evolution) algorithm in this *** the cost-benefits of the optimization were *** optimization was successfully performed but the accuracy of the optimization was slightly less than hoped when compared to the control modeling executed with the CFD(computational fluid dynamics).The mentioned inaccuracy could have been hardly avoided because of problems with an initial presumption involving semi-empiric calculations and of the uncertainty concerning the absolute areas of qualification of the *** kind of algebraic modeling was essential for the success of the optimization because ***-calculation could not have been done on each step of the *** the optimization some problems occurred with the adequacy of the computer capacity and with finding a suitable solution that would keep the algorithms within mathematically allowable boundaries but would not restrict the progress of the optimization too *** rest of the problems were due to the novelty of the application and problems with preciseness when handling the areas of qualification of the *** the accuracy of the optimization results was not exactly in accordance with the objective,they did have a favorable effect on the designing of the *** optimization executed with the help of the DE-algorithm got at least about 3.5 % more power out of the turbine which means about 150 000 € cost-benefit per turbine in the form of additional electricity capacity.

关键词：演化算法平均半径汽轮机优化通流部分差分进化算法计算流体力学多级