Radiative transfer model simulations were used to investigate the erythemal ultraviolet(EUV) correction factors by separating the UV-A and UV-B spectral ranges. The correction factor was defined as the ratio of EUV ca...Radiative transfer model simulations were used to investigate the erythemal ultraviolet(EUV) correction factors by separating the UV-A and UV-B spectral ranges. The correction factor was defined as the ratio of EUV caused by changing the amounts and characteristics of the extinction and scattering materials. The EUV correction factors(CFEUV) for UV-A[CFEUV(A)] and UV-B [CFEUV(B)] were affected by changes in the total ozone, optical depths of aerosol and cloud, and the solar zenith angle. The differences between CFEUV(A) and CFEUV(B) were also estimated as a function of solar zenith angle, the optical depths of aerosol and cloud, and total ozone. The differences between CFEUV(A) and CFEUV(B) ranged from-5.0% to 25.0% for aerosols, and from-9.5% to 2.0% for clouds in all simulations for different solar zenith angles and optical depths of aerosol and cloud. The rate of decline of CFEUV per unit optical depth between UV-A and UV-B differed by up to 20% for the same aerosol and cloud conditions. For total ozone, the variation in CFEUV(A) was negligible compared with that in CFEUV(B) because of the effective spectral range of the ozone absorption band. In addition, the sensitivity of the CFEUVs due to changes in surface conditions(i.e., surface albedo and surface altitude) was also estimated by using the model in this study. For changes in surface albedo, the sensitivity of the CFEUVs was 2.9%–4.1% per 0.1 albedo change,depending on the amount of aerosols or clouds. For changes in surface altitude, the sensitivity of CFEUV(B) was twice that of CFEUV(A), because the Rayleigh optical depth increased significantly at shorter wavelengths.展开更多
The offshore turbine system was installed on a floating platform moored in Hakata Bay, offshore of Fukuoka, Japan. An identical turbine system was also installed at the adjacent waterfront. The separation of the two t...The offshore turbine system was installed on a floating platform moored in Hakata Bay, offshore of Fukuoka, Japan. An identical turbine system was also installed at the adjacent waterfront. The separation of the two turbines was 3.7 km. Wind flow tends to be more stable and the average wind speed is often larger in offshore areas than adjacent land areas at typical wind turbine hub height. This study focused on the wind condition of a nearshore area to clarify the advantages of nearshore wind farming. Prior to field experiment, wind conditions were predicted by using numerical simulation. It is useful for estimating topographical effect in nearshore areas. Next, field verification test was done by directly comparing wind data obtained from the identical wind turbine systems installed at an offshore location and the adjacent waterfront over the same extended period. The corresponding power output of these turbines was also compared. The data set exhibits 23% larger annual average wind speed at the offshore location and smaller turbulent intensity, resulting doubled annual power production.展开更多
To grow high-quality and large-size monocrystalline silicon at low cost, we proposed a single-seed casting technique. To realize this technique, two challenges—polycrystalline nucleation on the crucible wall and disl...To grow high-quality and large-size monocrystalline silicon at low cost, we proposed a single-seed casting technique. To realize this technique, two challenges—polycrystalline nucleation on the crucible wall and dislocation multiplication inside the crystal—needed to be addressed. Numerical analysis was used to develop solutions for these challenges. Based on an optimized furnace structure and operating conditions from numerical analysis, experiments were performed to grow monocrystalline silicon using the single-seed casting technique. The results revealed that this technique is highly superior to the popular high-performance multicrystalline and multiseed casting mono-like techniques.展开更多
Hydriding properties of uranium alloys have been studied to search for new hydrogen storage materials to be applied to hydrogen energy systems. Application of uranium-base hydrogen storage materials can be expected to...Hydriding properties of uranium alloys have been studied to search for new hydrogen storage materials to be applied to hydrogen energy systems. Application of uranium-base hydrogen storage materials can be expected to alleviate the risk, as well as to reduce the cost incurred by globally-stored large amounts of depleted uranium left after uranium enrichment. Various uranium alloys have been examined in terms of hydrogen absorptiondesorption properties, among which UNi Al intermetallic compound showed promising characteristics, such as lower absorption-desorption temperatures and better anti-powdering strength. First principle calculation has been carried out on UNi Al hydride to predict the change of crystal structure and the lattice constant with increasing hydrogen content, which showed this calculation to be promising in predicting candidates for good hydrogen absorbers.展开更多
Moiré inteferometry and FEA (finite element analysis) were used to evaluate the thermal deformation of two electronic packages, QFP (quad flat package) and MCM (multi chip module).Thermal loading was applied by c...Moiré inteferometry and FEA (finite element analysis) were used to evaluate the thermal deformation of two electronic packages, QFP (quad flat package) and MCM (multi chip module).Thermal loading was applied by cooling the packages from 100℃ to room temperature (25℃). Moiré fringes were obtained on the cross sections of the packages to clarify the effect of the CTE (coefficient of thermal expansion) mismatch of the micro components, such as silicon, metal and resin. In QFP, the effects of packaging resin and PCB (printed circuit board) on the thermal deformation were investigated. The effect of location of three silicon chips in MCM was also examined.展开更多
The purpose of this study is to improve the efficiency of the power generation system of a solar tower using fluid dynamics. The power generation system of a solar tower can be designed and constructed at relatively l...The purpose of this study is to improve the efficiency of the power generation system of a solar tower using fluid dynamics. The power generation system of a solar tower can be designed and constructed at relatively low cost. However, the energy output tends to be low for its physical size compared with other renewable energy production systems. The technical and scientific improvement of these types of generation systems has lost its momentum since the shutdown of the wellknown Spanish pilot plant “Manzanares Solar Chimney” in 1989, although it still has the potential to play a role in renewable energy in the future. We have focused on the tower component of the system to seek possible enhancements of the power output of the internal turbine. As a result of our fluid dynamic shape optimization, a diffuser-shaped tower was employed to increase the internal flow speed of a scaled model. The results show a remarkable improvement in the power output of the internal wind turbine.展开更多
Possibility of the measurement of radiated waves derived from the thermally emittedelectron Bernstein wave(EBW)is numerically investigated based on the assumption of the superdense core(SDC)plasma generated in LHD.EBW...Possibility of the measurement of radiated waves derived from the thermally emittedelectron Bernstein wave(EBW)is numerically investigated based on the assumption of the superdense core(SDC)plasma generated in LHD.EBW that is thermally emitted in the electroncyclotron resonance(ECR)layer may couple with the electromagnetic wave and be emitted to thevacuum via the EBW-extraordinary-ordinary(B-X-O)mode conversion process.We consider theuse of one of the transmission lines for electron cyclotron heating(ECH)in LHD as a receivingsystem of the emission.It is derived that the waves in the fundamental cyclotron frequency rangeare emitted as the EBW near their upper hybrid resonance(UHR)layer outside the last close fluxsurface(LCFS).On the other hand,waves in the second harmonics cyclotron frequency range areemitted in the core region.It means that successful measurement of waves of the second harmonicfrequency range emitted from extremely high dense core plasma with setting an aim angle forreceiving indicates a possibility of the second harmonic ECH by EBW in the core region withsetting the same aim angle and the same polarization for launching.展开更多
The author’s research group has been conducting research on applications of various meteorological Grid Point Value (GPV) data offered by the Japan Meteorological Agency (JMA) to the field of wind power generation. I...The author’s research group has been conducting research on applications of various meteorological Grid Point Value (GPV) data offered by the Japan Meteorological Agency (JMA) to the field of wind power generation. In particular, the group’s research has been focusing on the following areas: 1) the use of GPV data from the JMA Meso-Scale Model (MSM-S;horizontal resolution: 5 km) and the JMA Local Forecast Model (LFM-S;horizontal resolution: 2 km), and 2) examinations of the prediction accuracy of local wind assessment with the use of these data. In both the MSM-S and the LFM-S, grid points are fixed at 10 m above the sea (ground) surface. The purpose of the present study is to establish a method in which the values of the MSM-S and LFM-S wind speed data from the 10 m height are used as the reference wind speed and are, using a power law, vertically extrapolated to 80 to 90 m heights, typical hub-heights of offshore wind turbines. For this purpose, the present study examined time-averaged vertical profiles of wind speed over the ocean based on the MSM-S data and in-situ data in the Hibikinada area, Kitakyushu City, Fukuoka Prefecture, Japan. As a result, it was revealed that a strong wind shear existed close to the sea surface, between the 10 and 30 m heights. In order to address the above-mentioned wind shear, a two-step vertical extrapolation method was proposed in the present study. In this method, two values of N, specifically for low and high altitudes (below and above approximately 30 m, respectively), were calculated and used. The data were created for the five years between 2012 and 2016. Similarly to previous analyses, the analysis of the created data set indicated that the potential of offshore wind power generation in the Hibikinada area, Kitakyushu City is quite high.展开更多
The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical ...The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical model for simulating unsteady flows called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COM putational Prediction of Airflow over Complex Terrain), which is based on the LES (Large-Eddy Simulation) technique. The computational domain of RIAM-COMPACT can be varied from several meters to several kilometers, and the model is able to predict airflow over complex terrain with high accuracy. The present paper discusses the application of RIAM-COMPACT to the micro-siting of wind turbines at sites outside Japan. The results from two case studies will be presented.展开更多
The original online version of this article (Masataka Motoyama, Kenichiro Sugitani, Yuji Ohya, et al. (2014) “Improving the Power Generation Performance of a Solar Tower Using Thermal Updraft Wind”, 2014, 6, 362-370...The original online version of this article (Masataka Motoyama, Kenichiro Sugitani, Yuji Ohya, et al. (2014) “Improving the Power Generation Performance of a Solar Tower Using Thermal Updraft Wind”, 2014, 6, 362-370. http://dx.doi.org/10.4236/epe.2014.611031) was published in October, 2014.The author wishes to correct the following error in text and Figures 9-11.展开更多
To obtain the interaction characteristics between Internal solitary waves(ISWs)and submerged bodies,a three-dimensional numerical model for simulating ISWs was established in the present study based on the RANS equati...To obtain the interaction characteristics between Internal solitary waves(ISWs)and submerged bodies,a three-dimensional numerical model for simulating ISWs was established in the present study based on the RANS equation.The velocity entrance method was adopted to generate the ISWs.First,the reliability of this numerical model was validated by comparing it with theoretical and literature results.Then,the influence of environmental and navigation parameters on interactions between ISWs and a fixed SUBOFF-submerged body was studied.According to research,the hydrodynamic performance of the submerged body has been significantly impacted by the ISWs when the body is nearing the central region of the wave.Besides,the pitching moment(y')will predominate when the body encounters the ISWs at a certain angle between 0°and 180°,and the lateral force is larger than the horizontal force.Additionally,the magnitude of the force acting on the body is mostly affected by the wave amplitude.The variation of the vertical force is the main way that ISWs affect the hydrodynamic performance of the bodies.The investigations and findings discussed above can serve as a guide to forecast how ISWs will interact with submerged bodies.展开更多
A power-supply system was developed for Ohmic heating(OH)to double×10^(18)the amount of change magnetic flux in the primary central solenoid(CS)on the QUEST spherical tokamak.Two power supplies are connected with...A power-supply system was developed for Ohmic heating(OH)to double×10^(18)the amount of change magnetic flux in the primary central solenoid(CS)on the QUEST spherical tokamak.Two power supplies are connected with stacks of insulated-gate bipolar transistors,and sequentially operated to generate positive and negative CS currents.This bipolar power-supply system is controlled via a field-programmable gate array,which guarantees the safety of the entire system operation.The new OH system,assisted by electron cyclotron heating,enables the stable generation of plasma currents exceeding 100 k A.Moreover,the achieved electron density over the wide range in the major radial direction exceeds the cut-off density for one of the highpower microwave sources in QUEST.This strategy yields target plasmas for future experiments with the electron Bernstein wave.展开更多
Enhancements of edge zonal flows,radial electric fields,and turbulence are observed in electron cyclotron resonance heating-heated plasmas(Zhao et al 2013 Nucl.Fusion 53083011).In this paper,the effects of sawtooth he...Enhancements of edge zonal flows,radial electric fields,and turbulence are observed in electron cyclotron resonance heating-heated plasmas(Zhao et al 2013 Nucl.Fusion 53083011).In this paper,the effects of sawtooth heat pulses on flows and turbulence are presented.These experiments are performed using multiple Langmuir probe arrays in the edge plasmas of the HL-2A tokamak.The edge zonal flows,radial electric fields,and turbulence are all enhanced by sawteeth.Propagation of the zonal flow and turbulence intensities is also observed.The delay time of the maximal intensity of the electric fields,zonal flows,and turbulence with respect to the sawtooth crashes is estimated as~1 ms and comparable to that of the sawtooth-triggered intermediate phases.Not only the zonal flows but also the radial electric fields lag behind the turbulence.Furthermore,the intensities of both the zonal flows and electric fields nearly linearly increase/decrease with the increase/decrease of the turbulence intensity.A double-source predator-prey model analysis suggests that a relatively strong turbulence source may contribute to the dominant zonal flow formation during sawtooth cycles.展开更多
The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tro...The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tropospheric ozone in March 1998. The calculated mixing ratios of ozone and carbon monoxide are compared with ground level observations at three remote sites in Japan and it is found that the model reproduces the observed features very well. Examination of several high episodes of ozone and carbon monoxide indicates that these elevated levels are found in association with continental outflow,demonstrating the critical role of the rapid transport of carbon monoxide and other ozone precursors from the continental boundary layer. In comparison with available ozonesonde data, it is found that the model-calculated ozone concentrations are generally in good agreement with the measurements, and the stratospheric contribution to surface ozone mixing ratios is quite limited.展开更多
In this paper,two novel numerical computation methods are introduced which have been recently developed at Research Institute for Applied Mechanics(RIAM),Kyushu University,for strongly nonlinear wave-body interaction ...In this paper,two novel numerical computation methods are introduced which have been recently developed at Research Institute for Applied Mechanics(RIAM),Kyushu University,for strongly nonlinear wave-body interaction problems,such as ship motions in rough seas and resulting green-water impact on deck.The first method is the CIP-based Cartesian grid method,in which the free surface flow is treated as a multi-phase flow which is solved using a Cartesian grid.The second method is the MPS method,which is a so-called particle method and hence no grid is used.The features and calculation procedures of these numerical methods are described.One validation computation against a newly conducted experiment on a dam break problem,which is also described in this paper,is presented.展开更多
The Duogu Wind Farm, China Huadian Group Corporation’s first wind project in Yunnan, China, has been approved by the Provincial Development and Reform Commission. The acquired site is in Mengzi, in the south-east of ...The Duogu Wind Farm, China Huadian Group Corporation’s first wind project in Yunnan, China, has been approved by the Provincial Development and Reform Commission. The acquired site is in Mengzi, in the south-east of Yunnan Province. The developer has deployed thirty-three 1.5 MW turbines in this wind farm (49.5 MW), and the total cost of construction has been estimated to be CNY449.7 million ($69.61 million). The present study compared the prediction accuracy of two CFD software packages for simulating flow over an escarpment with a steep slope. The two software packages were: 1) Open FOAM (Turbulence model: SST k-ω RANS), which is a free, open source CFD software package developed by Open CFD Ltd at the ESI Group and distributed by the Open FOAM Foundation and 2) RIAM-COMPACT (Turbulence model: Standard Smagorinsky LES), which has been developed by the lead author of the present paper. Generally good agreement was obtained between the results from the simulations with Open FOAM and RIAM-COMPACT.展开更多
The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5...The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5 × 103-1.2 × 104 and stratification parameters kd 0-2.0. The non-dimensional parameter kd is defined as kd = Nd/U, where N is the Brunt-Vaisala frequency, d, the diameter of the cylinder, and U, the approaching flow velocity. The study demonstrates that as kd increases from zero, the vortex shedding from a circular cylinder progressively strengthens, while the Strouhal number gradually becomes lower than that for homogeneous flow. This phenomenon can be explained by the effect of the increasingly stable stratification which enhances the two-dimensionality of the near-wake flow of the circular cylinder;the enhanced two-dimensionality of the flow strengthens the roll-up of the separated shear layer. Above a certain value of kd, however, vortex formation and shedding are strongly suppressed and the Strouhal number rises sharply. This observation is attributable to the development of stationary lee waves downstream of the circular cylinder because the lee waves strongly suppress vertical fluid motions.展开更多
基金funded by the Korea Meteorological Administration Research and Development Program (Grant No. KMIPA 2015-5170)
文摘Radiative transfer model simulations were used to investigate the erythemal ultraviolet(EUV) correction factors by separating the UV-A and UV-B spectral ranges. The correction factor was defined as the ratio of EUV caused by changing the amounts and characteristics of the extinction and scattering materials. The EUV correction factors(CFEUV) for UV-A[CFEUV(A)] and UV-B [CFEUV(B)] were affected by changes in the total ozone, optical depths of aerosol and cloud, and the solar zenith angle. The differences between CFEUV(A) and CFEUV(B) were also estimated as a function of solar zenith angle, the optical depths of aerosol and cloud, and total ozone. The differences between CFEUV(A) and CFEUV(B) ranged from-5.0% to 25.0% for aerosols, and from-9.5% to 2.0% for clouds in all simulations for different solar zenith angles and optical depths of aerosol and cloud. The rate of decline of CFEUV per unit optical depth between UV-A and UV-B differed by up to 20% for the same aerosol and cloud conditions. For total ozone, the variation in CFEUV(A) was negligible compared with that in CFEUV(B) because of the effective spectral range of the ozone absorption band. In addition, the sensitivity of the CFEUVs due to changes in surface conditions(i.e., surface albedo and surface altitude) was also estimated by using the model in this study. For changes in surface albedo, the sensitivity of the CFEUVs was 2.9%–4.1% per 0.1 albedo change,depending on the amount of aerosols or clouds. For changes in surface altitude, the sensitivity of CFEUV(B) was twice that of CFEUV(A), because the Rayleigh optical depth increased significantly at shorter wavelengths.
文摘The offshore turbine system was installed on a floating platform moored in Hakata Bay, offshore of Fukuoka, Japan. An identical turbine system was also installed at the adjacent waterfront. The separation of the two turbines was 3.7 km. Wind flow tends to be more stable and the average wind speed is often larger in offshore areas than adjacent land areas at typical wind turbine hub height. This study focused on the wind condition of a nearshore area to clarify the advantages of nearshore wind farming. Prior to field experiment, wind conditions were predicted by using numerical simulation. It is useful for estimating topographical effect in nearshore areas. Next, field verification test was done by directly comparing wind data obtained from the identical wind turbine systems installed at an offshore location and the adjacent waterfront over the same extended period. The corresponding power output of these turbines was also compared. The data set exhibits 23% larger annual average wind speed at the offshore location and smaller turbulent intensity, resulting doubled annual power production.
基金partly supported by the New Energy and Industrial Technology Development Organization (NEDO) under the Ministry of Economy,Trade and Industry (METI),Japan
文摘To grow high-quality and large-size monocrystalline silicon at low cost, we proposed a single-seed casting technique. To realize this technique, two challenges—polycrystalline nucleation on the crucible wall and dislocation multiplication inside the crystal—needed to be addressed. Numerical analysis was used to develop solutions for these challenges. Based on an optimized furnace structure and operating conditions from numerical analysis, experiments were performed to grow monocrystalline silicon using the single-seed casting technique. The results revealed that this technique is highly superior to the popular high-performance multicrystalline and multiseed casting mono-like techniques.
基金This project is supported by the Grants from Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP), China(No.20040698049)Natural Science Foundation of Xi'an Jiaotong University, China(No.2004).
基金Supported by Grants-in-Aid for Scientific Research(No.25420903)from the Ministry of Education,Culture,Sports,Science and Technology of Japan and Japan Industrial Location Center
文摘Hydriding properties of uranium alloys have been studied to search for new hydrogen storage materials to be applied to hydrogen energy systems. Application of uranium-base hydrogen storage materials can be expected to alleviate the risk, as well as to reduce the cost incurred by globally-stored large amounts of depleted uranium left after uranium enrichment. Various uranium alloys have been examined in terms of hydrogen absorptiondesorption properties, among which UNi Al intermetallic compound showed promising characteristics, such as lower absorption-desorption temperatures and better anti-powdering strength. First principle calculation has been carried out on UNi Al hydride to predict the change of crystal structure and the lattice constant with increasing hydrogen content, which showed this calculation to be promising in predicting candidates for good hydrogen absorbers.
文摘Moiré inteferometry and FEA (finite element analysis) were used to evaluate the thermal deformation of two electronic packages, QFP (quad flat package) and MCM (multi chip module).Thermal loading was applied by cooling the packages from 100℃ to room temperature (25℃). Moiré fringes were obtained on the cross sections of the packages to clarify the effect of the CTE (coefficient of thermal expansion) mismatch of the micro components, such as silicon, metal and resin. In QFP, the effects of packaging resin and PCB (printed circuit board) on the thermal deformation were investigated. The effect of location of three silicon chips in MCM was also examined.
文摘The purpose of this study is to improve the efficiency of the power generation system of a solar tower using fluid dynamics. The power generation system of a solar tower can be designed and constructed at relatively low cost. However, the energy output tends to be low for its physical size compared with other renewable energy production systems. The technical and scientific improvement of these types of generation systems has lost its momentum since the shutdown of the wellknown Spanish pilot plant “Manzanares Solar Chimney” in 1989, although it still has the potential to play a role in renewable energy in the future. We have focused on the tower component of the system to seek possible enhancements of the power output of the internal turbine. As a result of our fluid dynamic shape optimization, a diffuser-shaped tower was employed to increase the internal flow speed of a scaled model. The results show a remarkable improvement in the power output of the internal wind turbine.
基金supported in part by the JSPS-CAS Core-University program in the field of 'Plasma and Nuclear Fusion'
文摘Possibility of the measurement of radiated waves derived from the thermally emittedelectron Bernstein wave(EBW)is numerically investigated based on the assumption of the superdense core(SDC)plasma generated in LHD.EBW that is thermally emitted in the electroncyclotron resonance(ECR)layer may couple with the electromagnetic wave and be emitted to thevacuum via the EBW-extraordinary-ordinary(B-X-O)mode conversion process.We consider theuse of one of the transmission lines for electron cyclotron heating(ECH)in LHD as a receivingsystem of the emission.It is derived that the waves in the fundamental cyclotron frequency rangeare emitted as the EBW near their upper hybrid resonance(UHR)layer outside the last close fluxsurface(LCFS).On the other hand,waves in the second harmonics cyclotron frequency range areemitted in the core region.It means that successful measurement of waves of the second harmonicfrequency range emitted from extremely high dense core plasma with setting an aim angle forreceiving indicates a possibility of the second harmonic ECH by EBW in the core region withsetting the same aim angle and the same polarization for launching.
文摘The author’s research group has been conducting research on applications of various meteorological Grid Point Value (GPV) data offered by the Japan Meteorological Agency (JMA) to the field of wind power generation. In particular, the group’s research has been focusing on the following areas: 1) the use of GPV data from the JMA Meso-Scale Model (MSM-S;horizontal resolution: 5 km) and the JMA Local Forecast Model (LFM-S;horizontal resolution: 2 km), and 2) examinations of the prediction accuracy of local wind assessment with the use of these data. In both the MSM-S and the LFM-S, grid points are fixed at 10 m above the sea (ground) surface. The purpose of the present study is to establish a method in which the values of the MSM-S and LFM-S wind speed data from the 10 m height are used as the reference wind speed and are, using a power law, vertically extrapolated to 80 to 90 m heights, typical hub-heights of offshore wind turbines. For this purpose, the present study examined time-averaged vertical profiles of wind speed over the ocean based on the MSM-S data and in-situ data in the Hibikinada area, Kitakyushu City, Fukuoka Prefecture, Japan. As a result, it was revealed that a strong wind shear existed close to the sea surface, between the 10 and 30 m heights. In order to address the above-mentioned wind shear, a two-step vertical extrapolation method was proposed in the present study. In this method, two values of N, specifically for low and high altitudes (below and above approximately 30 m, respectively), were calculated and used. The data were created for the five years between 2012 and 2016. Similarly to previous analyses, the analysis of the created data set indicated that the potential of offshore wind power generation in the Hibikinada area, Kitakyushu City is quite high.
文摘The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical model for simulating unsteady flows called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COM putational Prediction of Airflow over Complex Terrain), which is based on the LES (Large-Eddy Simulation) technique. The computational domain of RIAM-COMPACT can be varied from several meters to several kilometers, and the model is able to predict airflow over complex terrain with high accuracy. The present paper discusses the application of RIAM-COMPACT to the micro-siting of wind turbines at sites outside Japan. The results from two case studies will be presented.
文摘The original online version of this article (Masataka Motoyama, Kenichiro Sugitani, Yuji Ohya, et al. (2014) “Improving the Power Generation Performance of a Solar Tower Using Thermal Updraft Wind”, 2014, 6, 362-370. http://dx.doi.org/10.4236/epe.2014.611031) was published in October, 2014.The author wishes to correct the following error in text and Figures 9-11.
基金financially supported by the Shandong Province Taishan Scholars Project (Grant No.tsqn201909172)Fundamental Research Funds for the Central Universities (Grant No.HIT.OCEF.2021037)+1 种基金the University Young Innovational Team Program,Shandong Province (Grant No.2019KJB004)the China Scholarship Council (Grant No.202106120123)。
文摘To obtain the interaction characteristics between Internal solitary waves(ISWs)and submerged bodies,a three-dimensional numerical model for simulating ISWs was established in the present study based on the RANS equation.The velocity entrance method was adopted to generate the ISWs.First,the reliability of this numerical model was validated by comparing it with theoretical and literature results.Then,the influence of environmental and navigation parameters on interactions between ISWs and a fixed SUBOFF-submerged body was studied.According to research,the hydrodynamic performance of the submerged body has been significantly impacted by the ISWs when the body is nearing the central region of the wave.Besides,the pitching moment(y')will predominate when the body encounters the ISWs at a certain angle between 0°and 180°,and the lateral force is larger than the horizontal force.Additionally,the magnitude of the force acting on the body is mostly affected by the wave amplitude.The variation of the vertical force is the main way that ISWs affect the hydrodynamic performance of the bodies.The investigations and findings discussed above can serve as a guide to forecast how ISWs will interact with submerged bodies.
基金supported by the NIFS Bilateral Collaboration Research Program(Nos.NIFS19-KUTR136,NIFS22KUTR169)Grant-in-Aid for Scientific Research(C)(No.21K03510)Collaborative Research Program of the RIAM in Kyushu University。
文摘A power-supply system was developed for Ohmic heating(OH)to double×10^(18)the amount of change magnetic flux in the primary central solenoid(CS)on the QUEST spherical tokamak.Two power supplies are connected with stacks of insulated-gate bipolar transistors,and sequentially operated to generate positive and negative CS currents.This bipolar power-supply system is controlled via a field-programmable gate array,which guarantees the safety of the entire system operation.The new OH system,assisted by electron cyclotron heating,enables the stable generation of plasma currents exceeding 100 k A.Moreover,the achieved electron density over the wide range in the major radial direction exceeds the cut-off density for one of the highpower microwave sources in QUEST.This strategy yields target plasmas for future experiments with the electron Bernstein wave.
基金National Natural Science Foundation of China(Nos.12075057,11775069,11320101005,and 11875020)National Magnetic Confinement Fusion Science Program of China(No.2017YFE0301201)+3 种基金East China University of Technology,Doctoral Foundation(Nos.DHBK 2017134 and DHBK 2018059)Grant-in-Aid for Scientific Research of the Japan Society for the Promotion of Science(Nos.15H02155,15H02335,21K03513)Landmark Achievements in Nuclear Science and Technology(No.xxkjs2018011)Natural Science Foundation of Jiangxi Province(Nos.20202ACBL201002 and 0192ACB80006)。
文摘Enhancements of edge zonal flows,radial electric fields,and turbulence are observed in electron cyclotron resonance heating-heated plasmas(Zhao et al 2013 Nucl.Fusion 53083011).In this paper,the effects of sawtooth heat pulses on flows and turbulence are presented.These experiments are performed using multiple Langmuir probe arrays in the edge plasmas of the HL-2A tokamak.The edge zonal flows,radial electric fields,and turbulence are all enhanced by sawteeth.Propagation of the zonal flow and turbulence intensities is also observed.The delay time of the maximal intensity of the electric fields,zonal flows,and turbulence with respect to the sawtooth crashes is estimated as~1 ms and comparable to that of the sawtooth-triggered intermediate phases.Not only the zonal flows but also the radial electric fields lag behind the turbulence.Furthermore,the intensities of both the zonal flows and electric fields nearly linearly increase/decrease with the increase/decrease of the turbulence intensity.A double-source predator-prey model analysis suggests that a relatively strong turbulence source may contribute to the dominant zonal flow formation during sawtooth cycles.
基金supported by the National Natural Science Foundation of China(Grant No.40245029)the Hundred Talents Program(Global Environmental Change)from the Chinese Academy of Sciences.
文摘The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is applied to East Asia to study the transport and photochemical transformation of tropospheric ozone in March 1998. The calculated mixing ratios of ozone and carbon monoxide are compared with ground level observations at three remote sites in Japan and it is found that the model reproduces the observed features very well. Examination of several high episodes of ozone and carbon monoxide indicates that these elevated levels are found in association with continental outflow,demonstrating the critical role of the rapid transport of carbon monoxide and other ozone precursors from the continental boundary layer. In comparison with available ozonesonde data, it is found that the model-calculated ozone concentrations are generally in good agreement with the measurements, and the stratospheric contribution to surface ozone mixing ratios is quite limited.
文摘In this paper,two novel numerical computation methods are introduced which have been recently developed at Research Institute for Applied Mechanics(RIAM),Kyushu University,for strongly nonlinear wave-body interaction problems,such as ship motions in rough seas and resulting green-water impact on deck.The first method is the CIP-based Cartesian grid method,in which the free surface flow is treated as a multi-phase flow which is solved using a Cartesian grid.The second method is the MPS method,which is a so-called particle method and hence no grid is used.The features and calculation procedures of these numerical methods are described.One validation computation against a newly conducted experiment on a dam break problem,which is also described in this paper,is presented.
文摘The Duogu Wind Farm, China Huadian Group Corporation’s first wind project in Yunnan, China, has been approved by the Provincial Development and Reform Commission. The acquired site is in Mengzi, in the south-east of Yunnan Province. The developer has deployed thirty-three 1.5 MW turbines in this wind farm (49.5 MW), and the total cost of construction has been estimated to be CNY449.7 million ($69.61 million). The present study compared the prediction accuracy of two CFD software packages for simulating flow over an escarpment with a steep slope. The two software packages were: 1) Open FOAM (Turbulence model: SST k-ω RANS), which is a free, open source CFD software package developed by Open CFD Ltd at the ESI Group and distributed by the Open FOAM Foundation and 2) RIAM-COMPACT (Turbulence model: Standard Smagorinsky LES), which has been developed by the lead author of the present paper. Generally good agreement was obtained between the results from the simulations with Open FOAM and RIAM-COMPACT.
文摘The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5 × 103-1.2 × 104 and stratification parameters kd 0-2.0. The non-dimensional parameter kd is defined as kd = Nd/U, where N is the Brunt-Vaisala frequency, d, the diameter of the cylinder, and U, the approaching flow velocity. The study demonstrates that as kd increases from zero, the vortex shedding from a circular cylinder progressively strengthens, while the Strouhal number gradually becomes lower than that for homogeneous flow. This phenomenon can be explained by the effect of the increasingly stable stratification which enhances the two-dimensionality of the near-wake flow of the circular cylinder;the enhanced two-dimensionality of the flow strengthens the roll-up of the separated shear layer. Above a certain value of kd, however, vortex formation and shedding are strongly suppressed and the Strouhal number rises sharply. This observation is attributable to the development of stationary lee waves downstream of the circular cylinder because the lee waves strongly suppress vertical fluid motions.
