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Journal of Thermal Science 2011年第2期20卷 97-105页

作者： Ahti Jaatinen aki grnman Teemu Turunen-Saaresti Jari Backman Lappeenranta University of Technology

Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotational speeds, and flow angles before and after the diffuser are measured at the design rotational speed and with three mass flow rates. The results are compared to corresponding results of the original vaneless diffuser design. Attention is paid to the performance at lower mass flows than the design mass flow. The results show that it is possible to improve the performance at mass flows lower than the design mass flow with a vaned diffuser designed with high negative incidence. However, with the vaned diffusers, the compressor still stalls at higher mass flow rates than with the vaneless one. The flow angle distributions after the diffuser are more uniform with the vaned diffusers.

关键词： centrifugal compressor vaned diffuser efficiency performance flow field

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Numerical Modelling of a Supersonic Axial Turbine Stator

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Journal of Thermal Science 2010年第3期19卷 211-217页

作者： aki grnman Teemu Turunen-Saaresti Ahti Jaatinen Jari Backman LUT Energy Lappeenranta University of TechnologyP.O.Box 20FI-53851 LappeenrantaFinland

In order to improve the turbocharging process,a supersonic axial turbine stator was modelled numerically with a pulsatile inlet mass *** main objectives of the study were to find out how pulsation affects the flow field and the performance of the *** the beginning of the study,a supersonic turbine stator was modelled using three different techniques:quasi-steady,time-accurate with constant boundary conditions and time-accurate with a pulsatile inlet mass *** time-averaged and quasi-steady flow fields and performance were compared,and the flow field and stator performance with a pulsatile inlet mass flow was studied in detail at different time-steps.A hysteresis-like behaviour was captured when the total-to-static pressure ratio and efficiency were plotted as a function of the inlet mass flow over one pulse *** total-to-static pressure ratio and efficiency followed the sinusoidal shape of the inlet flow as a function of *** was also concluded that the stator efficiency decreases downstream from the stator trailing edge and the amplitude of the pulsating mass flow is decreased at the stator throat.

关键词： CFD Supersonic Turbine Stator Turbocharging

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Characteristics of Energy Fluxes and Cold Frontal Effects on Energy Exchange over a Boreal Lake

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Advances in Atmospheric Sciences 2025年第2期42卷 357-372页

作者： Lujun XU Huizhi LIU Ivan MAMMARELLA aki VÄHÄ Joonatan ALA-KÖNNI Xuefei LI Qun DU Yang LIU Timo VESALA State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100864China Department of Atmospheric Sciences Yunnan UniversityKunming 650091China Institute for Atmospheric and Earth System Research/Physics Faculty of ScienceUniversity of HelsinkiHelsinki 00014Finland

Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable *** on eddy covariance measurements over Lake Vanajavesi in southern Finland,characteristics of energy fluxes and cold frontal effects on energy exchange were *** lake acted as a heat sink in spring and summer and a heat source in *** latent heat flux reached its minimum value in the morning and peaked in the *** diurnal variation of sensible heat flux was opposite to that of latent heat *** factors for the sensible heat flux were mainly the lake-air temperature difference and the product of lake-air temperature difference and wind *** latent heat flux was mainly affected by the vapor pressure deficit and the product of vapor pressure deficit and wind *** annual mean values of bulk transfer coefficients for momentum,heat,and water vapor were 1.98×10^(-3),1.62×10^(-3),and 1.31×10^(-3),*** transfer coefficients for heat and water vapor were not equal,indicating that the parameterization of energy exchange in numerical models,where the assumption that the heat coefficient equals the water vapor coefficient needs *** the ice-free season,cold fronts resulted in 28 sensible heat pulses and 17 latent heat pulses,contributing to 50.59%and 34.89%of sensible and latent heat exchange in Lake *** results indicate that cold fronts significantly impact the surface energy budget and evaporation over lakes.

关键词： sensible heat flux latent heat flux roughness length bulk transfer coefficient cold front

Characteristics of Energy Fluxes and Cold Frontal Effects on Energy Exchange over a Boreal Lake

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Advances in Atmospheric Sciences 2025年第02期 357-372页

作者： Lujun XU Huizhi LIU Ivan MAMMARELLA aki V?H? Joonatan ALA-K?NNI Xuefei LI Qun DU Yang LIU Timo VESALA State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Atmospheric Sciences Yunnan University Institute for Atmospheric and Earth System Research/Physics Faculty of ScienceUniversity of Helsinki

Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development. Based on eddy covariance measurements over Lake Vanajavesi in southern Finland, characteristics of energy fluxes and cold frontal effects on energy exchange were investigated. The lake acted as a heat sink in spring and summer and a heat source in winter. The latent heat flux reached its minimum value in the morning and peaked in the afternoon. The diurnal variation of sensible heat flux was opposite to that of latent heat flux. Impact factors for the sensible heat flux were mainly the lake-air temperature difference and the product of lake-air temperature difference and wind speed. The latent heat flux was mainly affected by the vapor pressure deficit and the product of vapor pressure deficit and wind speed. The annual mean values of bulk transfer coefficients for momentum, heat,and water vapor were 1.98 × 10–3, 1.62 × 10–3, and 1.31 × 10–3, respectively. Bulk transfer coefficients for heat and water vapor were not equal, indicating that the parameterization of energy exchange in numerical models, where the assumption that the heat coefficient equals the water vapor coefficient needs improvement. During the ice-free season, cold fronts resulted in 28 sensible heat pulses and 17 latent heat pulses, contributing to 50.59% and 34.89% of sensible and latent heat exchange in Lake Vanajavesi. These results indicate that cold fronts significantly impact the surface energy budget and evaporation over lakes.

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Influences of additives on phosphoric acid treatment of titanium dioxide as a novel white pigment

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Journal of Advanced Ceramics 2015年第3期4卷 211-216页

作者： aki MATSUKURA Hiroaki ONODA Department of Informatics and Environmental Sciences Kyoto Prefectual University1-5Shimogamo Nakaragi-cyoSakyo-kuKyoto 606-8522Japan

Titanium dioxide is a photocatalytically active substance used as a white pigment for *** sunlight,titanium dioxide catalyzes decomposition of a certain amount of sebum on the skin by ultraviolet ***,a novel white pigment for use in cosmetics was developed from titanium dioxide and phosphoric acid at pH=4 with and without glycerin,sodium lactate,lactic acid,and *** chemical composition,powder properties,photocatalytic activity,color phase,and smoothness of the samples were *** of glycerin led to a decline in the intensity of the X-ray diffraction(XRD)peak of TiO_(2) relative to that of the other *** particle size of the materials prepared with and without additives was 0.3μm;however,extensive aggregation was observed in the obtained *** photocatalytic activity of TiO_(2) was inhibited by phosphoric acid *** materials prepared with sodium lactate,lactic acid,and glycerin exhibited higher photocatalytic activity than that prepared without *** obtained materials showed a high reflectance in the range of visible light,and the L^(*)values in L^(*)a^(*)b^(*) color space were high(where L^(*)defines lightness,a^(*) denotes the red/green value,and b^(*) the yellow/blue value).These results indicate that the samples prepared in this work are suitable for use as white pigments.

关键词： phosphoric acid titanium dioxide photocatalytic activity particle size

Accurate real-time truck simulation via semirecursive formulation and Adams-Bashforth-Moulton algorithm

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Acta Mechanica Sinica 2019年第3期35卷 641-652页

作者： Yongjun Pan Yansong He aki Mikkola School of Automotive Engineering Chongqing UniversityChongqing 400044China Department of Mechanical Engineering Lappeenranta University of Technology53850 LappeenrantaFinland

In this paper, a tailored four-step Adams-Bashforth-Moulton (ABM) algorithm is applied to a semirecursive formulation to perform a real-time simulation of a semitrailer truck. In the ABM algorithm, each integration step involves two function evaluations, namely predictor and corrector. This is fundamentally different when compared to the classic fourth-order Runge-Kutta (RK) integrator approach that contains four function evaluations. A semitrailer truck under investigation is modeled in term of a semirecursive method and simulated by using the presented ABM algorithm. The results show that the four-step ABM method can reduce CPU time almost 50% for solving the truck dynamics with very similar accuracy, in comparison to the fourth-order RK method. The presented ABM algorithm could be used in the semirecursive formulation to carry out accurate real-time simulation of medium-large vehicle systems.

关键词： Numerical algorithm Semirecursive formulation Vehicle dynamics Computational efficiency

Karyotype differentiation and reproductive isolation among natural populations of Drosophila lacertosa

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Cell Research 2003年第6期13卷 491-497页

作者： HIDE aki WATABE,TADASHI AOTSUKA Biological Laboratory Sapporo College Hokkaido University of Education Sapporo 002-8502 Japan Department of Biology Tokyo Metropolitan University Hachioji-shi 192-0397 Japan

Drosophila lacertosa is widely distributed from northern India to Far East of Russia throughout China. We have studied geographical distributions of three kinds of chromosomal karyotypes, type D (2n=10, 4 pairs of V-shaped metacentric chromosomes and a pair of micro-chromosomes), type L (2n=10, 5V with a pair of large-sized hetero chromatic autosomes) and type M (2n=10, 5V with middle-sized ones). Type D was found exclusively in local populations of D. lacertosa distributed in Yun-Gui Plateau, southwestern China. Both type L and M have a wide range of distribution, and the former occurred in subtropical regions of China including Taiwan Island, whereas the latter in cool temperate regions of East Asia covering Far East of Russia, Korea and the Japan Islands. A strong pre mating isolation was detected between flies with type D and those with type L or M. These data demonstrate that genetic differentiation leading to cryptic speciation might have occurred in natural populations of Drosophila lacertosa.

关键词： Drosophila lacertosa karyotype differentiation geographic distribution reproductive isolation cryptic speciation.

Fabrication of Mie-resonant silicon nanoparticles using laser annealing for surface-enhanced fluorescence spectroscopy

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Microsystems & Nanoengineering 2024年第2期10卷 133-141页

作者： Tatsuya Fukuta Ryo Kato Takuo Tanaka Taka-aki Yano Institute of Post-LED Photonics Tokushima University2-1 Minami-JosanjimaTokushima770-8506Japan Innovative Photon Manipulation Research Team RIKEN Center for Advanced PhotonicsWakoSaitama351-0198Japan Metamaterials Laboratory RIKEN Cluster for Pioneering ResearchWakoSaitama351-0109Japan

Silicon nanostructures with unique Mie resonances have garnered considerable attention in the field of ***,we present a simple and efficient method for the fabrication of silicon(Si)nanoparticle substrates using continuous-wave(CW)laser *** resulting silicon nanoparticles exhibit Mie resonances in the visible region,and their resonant wavelengths can be precisely ***,laser-annealed silicon nanoparticle substrates show a 60-fold enhancement in *** tunable and fluorescence-enhancing silicon nanoparticle platform has tremendous potential for highly sensitive fluorescence sensing and biomedical imaging applications.

关键词： nanoparticles annealing resonant

Addressing e-cigarette health claims made on social media amidst the COVID-19 pandemic

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World Journal of Pediatrics 2021年第1期17卷 3-5页

作者： Nilanga aki Bandara Jay Herath Vahid Mehrnoush University of British Columbia Faculty of Education 6081 University BlvdVancouverBC V6T 1Z1Canada University of British Columbia Faculty of Medicine 317-2194 Health Sciences MallVancouver V6T 1Z3BCCanada

We are in a global pandemic that is responsible for more than 73.6 million confirmed cases and over 1.64 million *** evidence highlights that electronic cigarette(e-cig)use by young people has a strong association with COVID-19 diagnosis[1].The e-cig industry has successfully utilized social media platforms to market e-cigs to adolescents[2].The industry typically posts on various social media sites,such as Ins-tagram and Reddit,frequented by adolescents.

关键词： media typically utilized

SINGLE AND DOUBLE EDGE INTERFACE CRACK SOLUTIONS FOR ARBITRARY FORMS OF MATERIAL COMBINATION

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Acta Mechanica Solida Sinica 2012年第4期25卷 404-416页

作者： Xin Lan Nao-aki Noda Kengo Michinaka Department of Mechanical Engineering Kyushu Institute of Technology

In this paper interfacial edge crack problems are considered by the application of the finite element method. The stress intensity factors are accurately determined from the ratio of crack-tip-stress value between the target given unknown and reference problems. The reference problem is chosen to produce the singular stress fields proportional to those of the given unknown problem. Here the original proportional method is improved through utilizing very refined meshes and post-processing technique of linear extrapolation. The results for a double-edge interface crack in a bonded strip are newly obtained and compared with those of a single-edge interface crack for different forms of combination of material. It is found that the stress intensity factors should be compared in the three different zones of relative crack lengths. Different from the case of a cracked homogeneous strip, the results for the double edge interface cracks are found to possibly be bigger than those for a single edge interface crack under the same relative crack length.

关键词： stress intensity factor single edge interface crack double edge interface crack combination of material bonded strip

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