Oscillating heat pipes (OHPs) are very promising cooling devices. Their heat transfer performance is af- fected by many factors, and the form of the relationship between the performance and the factors is complex and ...Oscillating heat pipes (OHPs) are very promising cooling devices. Their heat transfer performance is af- fected by many factors, and the form of the relationship between the performance and the factors is complex and non-linear. In this paper, the effects of charging ratio, inclination angle, and heat input and their interaction effects on heat transfer performance of a looped copper-water OHP are analyzed. First, suppose that the relationship between the response and the variables approximates a second-order model. And use the central composite design to arrange the ex- periment. Then, the method of least squares is used to estimate the parameters in the second-order model. Finally, multi- variate variance analysis is used to analyze the model. The results show that the assumption is right, that is to say, the re- lationship is well modeled by a second-order function. Among the three main effect variables, the effect of inclination angle is the most significant, but their interaction effects are not significant. In the range of the considered factors, both the optimum charging ratio and the optimum inclination angle increase as the heating water flow rate increases.展开更多
As for the factors affecting the heat transfer performance of complex and nonlinear oscillating heat pipe (OHP),grey relational analysis (GRA) was used to deal with the relationship between heat transfer rate of a loo...As for the factors affecting the heat transfer performance of complex and nonlinear oscillating heat pipe (OHP),grey relational analysis (GRA) was used to deal with the relationship between heat transfer rate of a looped copper-water OHP and charging ratio,inner diameter,inclination angel,heat input,number of turns,and the main influencing factors were defined.Then,forecasting model was obtained by using main influencing factors (such as charging ratio,interior diameter,and inclination angel) as the inputs of function chain neural network.The results show that the relative average error between the predicted and actual value is 4%,which illustrates that the function chain neural network can be applied to predict the performance of OHP accurately.展开更多
The pressure characteristics inside single loop oscillating heat pipe (OHP) having 4.5 mm inner diameter copper tube with the loop height of 440 mm were addressed. Distilled water was used as working fluid inside th...The pressure characteristics inside single loop oscillating heat pipe (OHP) having 4.5 mm inner diameter copper tube with the loop height of 440 mm were addressed. Distilled water was used as working fluid inside the OHP with different filling ratios of 40%, 60% and 80% of total inside volume. Experimental results show that the thermal characteristics are significantly inter-related with pressure fluctuations as well as pressure frequency. And the pressure frequency also depends upon the evaporator temperature that is maintained in the range of 60-96 ℃. Piezoresistive absolute pressure sensor (Model-Kistler 4045A5) was used to take data. The investigation shows that the filling ratio of 60% gives the highest inside pressure magnitude at maximum number of pressure frequency at any of set evaporator temperature and the lowest heat flow resistance is achieved at 60% filling ratio.展开更多
The effects of air-sea coupling over the tropical Indian Ocean(TIO) on the eastward propagating boreal winter intraseasonal oscillation(MJO) are investigated by comparing a fully coupled and a partially decoupled ...The effects of air-sea coupling over the tropical Indian Ocean(TIO) on the eastward propagating boreal winter intraseasonal oscillation(MJO) are investigated by comparing a fully coupled and a partially decoupled Indian Ocean experiment using the SINTEX-F coupled model.Air-sea coupling over the TIO significantly enhances the intensity of the eastward propagations of the MJO along the5°-10°S zonal areas.The zonal asymmetry of the SST anomaly(SSTA) is responsible for the enhanced eastward propagation.A positive SSTA appears to the east of the MJO convection,which results in the boundary layer moisture convergence and positively feeds back to the MJO convection.In addition,the air-sea interaction effect on the eastward propagation of the MJO is related to the interannual variations of the TIO.Air-sea coupling enhances(reduces) the eastward-propagating spectrum during the negative Indian Ocean dipole mode and positive Indian Ocean basin mode.Such phase dependence is attributed to the role of the background mean westerly in affecting the wind-evaporation-SST feedback.Air-sea coupling(decoupling) enhances(reduces) the zonal asymmetry of the low-level specific humidity,and thus the eastward propagation spectrum of the MJO.展开更多
Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop pl...Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop plate oscillating heat pipe with parallel channels(POHP-PC) were experimentally investigated by varying liquid filled ratios(50%, 70%, 85%), section scales(1 mm×1 mm and 1 mm×1.5 mm), inclination angles, working fluids and heating inputs. It was found that during operating there was mixed flow consisting of plug flow and annular flow in channels of oscillating heat pipe at steady-state. There was an equilibrium position for working fluid of condenser during oscillating, and periodic oscillations occurred up and down in the vicinity of equilibrium position. With heat input increasing, equilibrium position rose slowly as a result of vapor pressure of evaporation.Evaporation temperature oscillating amplitude possessed a trend of small-large-small and frequency trend was of small-large during steady-state. It may be generally concluded that temperature, whether evaporator or condenser, fluctuated sharply or rose continuously when oscillating heat pipe coming to dry burning state. Simultaneously, it was found that temperature difference of cooling water possibly dropped with heat input rising during dry burning state. Thermal resistance of No. 2 with acetone was lower than that of No. 1 during experiments, but No. 2 achieving heat transfer limit was earlier than No. 1. However, with ethanol, thermal resistance of No. 1 and No. 2 were similar with the heating input less than 110-120 W and filling ratios of 50% and 70%. And with filling ratio of 85%, heating transfer performance of No. 2 was better compared to No. 1 during all the experiments.展开更多
The temporal variations in the frequency of tropical cyclones (TCs) traversing the Taiwan and Hainan Islands (TH islands), were analyzed using a best-track TC dataset from the Joint Typhoon Warning Center for the peri...The temporal variations in the frequency of tropical cyclones (TCs) traversing the Taiwan and Hainan Islands (TH islands), were analyzed using a best-track TC dataset from the Joint Typhoon Warning Center for the period 1945-2007. Results show that the oscillations were interannual and interdecadal on the timescales of 2-8 and 8-12 years, respectively. It is also shown that the number of TCs formed in the western North Pacific basin (WNP) and of those traversing the TH islands varied intraseasonally. These results also held for typhoons traversing the TH islands, although the oscillations were less apparent. This study identified interrelationships between the frequency of TCs making landfall on the TH islands and the East Asia summer monsoon (EASM), the South Asia summer monsoon (SASM), and the South China Sea summer monsoon (SCSSM). The SCSSM significantly influenced the number of TCs traversing Hainan Island, but had little influence on the number of TCs traversing Taiwan Island. By contrast, the SASM influenced the numbers of TCs traversing both of the TH islands, shown by correlation coefficients of 0.41 for Taiwan Island and -0.25 for Hainan Island. In addition, the frequency of TC landfall on Taiwan Island increased during years of enhanced EASM, as indicated by a correlation coefficient of 0.4.展开更多
Using the daily average outgoing longwave radiation and NCEP/NCAR reanalysis data in boreal summer(Mays to Octobers)from 1979 to 2007,the propagating characteristics of convection intraseasonal oscillations(ISOs)in th...Using the daily average outgoing longwave radiation and NCEP/NCAR reanalysis data in boreal summer(Mays to Octobers)from 1979 to 2007,the propagating characteristics of convection intraseasonal oscillations(ISOs)in the Asian-western Pacific(AWP)region and the relationship between tropical synoptic waves and ISOs are examined by means of finite-domain wavenumber-frequency energy spectrum analysis and lagged linear regression technique.The results are shown as follows.(1)The AWP ISOs propagate both eastward and westward,showing seasonality and regionality.The ISOs propagate eastward with a period of 30 to 60 days over equatorial regions in the whole AWP region,while the westward propagation occurs over 10 to 20°N western Pacific or in the late summers(August,September and October) with periods of 20 to 40 days.The ISOs eastward propagation mainly occurs in primary summers while the westward propagation enhances in late summers.(2)Deep ISO convections associate with westerly and cyclonic circulation anomalies that first form in the Indian Ocean,propagate eastward to the dateline in the Pacific and then turn northwestward.The ISOs convections show northwestward propagating characteristics in the western North Pacific.(3)The ISOs link with the tropical synoptic waves closely.Both convection signals,though with different spatio-temporal scale,enhance simutaneously in the northwestern Pacific,and the ISOs facilitate the forming of a cluster of tropical cyclones(TCs),while a cluster of TCs convection becomes one portion of the northwestward ISOs.展开更多
This study utilizes a new monthly-assimilated sea temperature and analyzes trend and decadal oscillations in tropical Pacific 100 200 m subsurface ocean temperature (SOT) from 1945 to 2005 on the basis of the harmonic...This study utilizes a new monthly-assimilated sea temperature and analyzes trend and decadal oscillations in tropical Pacific 100 200 m subsurface ocean temperature (SOT) from 1945 to 2005 on the basis of the harmonic analysis and Empirical Orthogonal Function (EOF) methods.Significant cooling trends in the SOT in the tropical western Pacific were found over this 60-year period.The first EOF of the SOT in tropical Pacific displays an ENSO-like zonal dipole pattern on decadal time scale,and we considered this pattern in subsurface ocean temperature the tropical Pacific decadal oscillation (TPDO).Our analysis suggests that TPDO is closely correlated with the Pacific decadal oscillation (PDO) in the surface sea temperature (SST).The correlation coefficient between the indices of TPDO and PDO is +0.81 and reaches a maximum of +0.84 when TPDO lags behind PDO by 2 months.Therefore,a change of TPDO is likely related to the variation of PDO.The long-term change in TPDO best explains decadal warming in the tropical eastern Pacific SST and implies potential impact on the weakening of East Asian summer monsoons after the late 1970s.展开更多
Gene transcriptional regulation (TR) processes are often described by coupled nonlinear ordinary differential equations (ODEs). When the dimension of TR circuits is high (e.g. n≥3) the motions of the correspond...Gene transcriptional regulation (TR) processes are often described by coupled nonlinear ordinary differential equations (ODEs). When the dimension of TR circuits is high (e.g. n≥3) the motions of the corresponding ODEs may, very probably, show self-sustained oscillations and chaos. On the other hand, chaoticity may be harmful for the normal biological functions of TR processes. In this letter we numerically study the dynamics of 3-gene TR ODEs in great detail, and investigate many 4-, 5-, and lO-gene TR systems by randomly choosing figures and parameters in the conventionally accepted ranges. And we find that oscillations are very seldom and no chaotic motion is observed, even if the dimension of systems is sufficiently high (n≥3). It is argued that the observation of nonchaoticity of these ODEs agrees with normal functions of actual TR processes.展开更多
Effective thermal performance of oscillating heat pipe(OHP)is driven by inside pressure distribution.Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP c...Effective thermal performance of oscillating heat pipe(OHP)is driven by inside pressure distribution.Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP charged with aqueous Al2O3 and MWCNTs/Al2O3 nanoparticles.The influences on thermal resistance of aqueous Al2O3,MWCNTs as well as the hybrid of them in OHP having 3 mm in inner diameter were investigated at 60% filling ratio.Experimental results show that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations with time.Frequency of pressure depends upon the power input in evaporative section.A little inclusion of MWCNTs into aqueous Al2O3 at 60% filling ratio achieves the highest fluctuation frequency and the lowest thermal resistance at any evaporator power input though different nanofluids cause different thermal performances of OHPs.展开更多
This paper focuses on the impacts of convective momentum transport(CMT) on simulations of the tropical intraseasonal oscillation(TIO) in SAMIL. Two sets of experiments are performed, which give different reality of th...This paper focuses on the impacts of convective momentum transport(CMT) on simulations of the tropical intraseasonal oscillation(TIO) in SAMIL. Two sets of experiments are performed, which give different reality of the Madden-Julian Oscillation(MJO). The Tiedtke cumulus parameterization scheme is used for all experiments. It is found that simulations of the TIO can be influenced by CMT, and the impacts on the simulated TIO depend on the model capability in simulating the MJO. CMT tends to have large influences to the model that can simulate the eastward propagation of the MJO. CMT can further influence the long-term mean of zonal wind and its vertical shear. Zonal wind suffers from easterlies biases at low level and westerlies biases at upper level when CMT is introduced. Such easterlies biases at low level reduce the reality of the simulated tropical intraseasonal oscillation. When CMT is introduced in the model, MJO signals disappear but the model's mean state improves. Therefore, a more appropriate way is needed to introduce CMT to the model to balance the simulated mean state and TIO signals.展开更多
In order to explain the oscillation heat transfer dynamics of closed loop oscillation heat pipe (CLOHP) with two liquid slugs,analysis on the forces and heat transfer process of the partial gas-liquid phase system inv...In order to explain the oscillation heat transfer dynamics of closed loop oscillation heat pipe (CLOHP) with two liquid slugs,analysis on the forces and heat transfer process of the partial gas-liquid phase system involving multiple parameters was carried out,and a new type oscillation heat transfer dynamic model of the CLOHP was set up based on conservation laws of mass,momentum and energy.Application results indicate that its oscillation heat transfer dynamics features depend largely on the filling rate,pipe diameter and difference in temperature.Besides,oscillation intensity and transfer performance can be improved to a large extent by increasing the temperature difference properly and enlarging the pipe diameter within a certain range under a certain filling rate.展开更多
The heat distributions in the upper layers of the ocean have been studied and some important low frequency oscillations (LFOs) are already found and quantified by using various characteristic factors. In this paper,...The heat distributions in the upper layers of the ocean have been studied and some important low frequency oscillations (LFOs) are already found and quantified by using various characteristic factors. In this paper, the ‘heat center' of a sea area is defined with a simple method. Then the temperature data set of the upper layer of the global ocean (from surface down to 400 m, 1955-2003) is analyzed to detect the possible LFOs. Not only some zonal LFOs, which were reported early, but also some strong LFOs of the vertical and meridional heat distribution, which might imply some physical sense, are detected. It should be noted that the similar vertical oscillation pattern can be found in the Pacific Ocean, Atlantic Ocean and Indian Ocean. Results from some preliminary studies show that the vertical LFO might be caused by the solar irradiance anomalies. This study may help reveal some unknown dynamical processes in the global oceans and may also benefit other related studies.展开更多
This study evaluates the performance of the Grid-point Atmospheric Model of IAP LASG,version 3(GAMIL3),in simulating the Madden–Julian Oscillation(MJO),based on the CMIP6(phase 6 of the Coupled Model Intercomparison ...This study evaluates the performance of the Grid-point Atmospheric Model of IAP LASG,version 3(GAMIL3),in simulating the Madden–Julian Oscillation(MJO),based on the CMIP6(phase 6 of the Coupled Model Intercomparison Project)AMIP(Atmospheric Model Intercomparison Project)simulation.Results show that GAMIL3 reasonably captures the main features of the MJO,such as the eastward-propagating signal in the MJO frequency band,the symmetric and asymmetric structures of the MJO,several convectively coupled equatorial waves,and the MJO life cycle.However,GAMIL3 underestimates the MJO amplitude,especially for outgoing longwave radiation,as do most CMIP5 models,and simulates slow eastward propagation.展开更多
Drum level sloshing is the latest discovery in the application of heat recovery steam generator (HRSG) in combined cycle, and shows certain negative influence on drum level controlling. In order to improve drum level ...Drum level sloshing is the latest discovery in the application of heat recovery steam generator (HRSG) in combined cycle, and shows certain negative influence on drum level controlling. In order to improve drum level controlling, influence factors on the drum level sloshing were investigated. Firstly, drum sub-modules were developed using the method of modularization modeling, and then the model of drum level sloshing was set up as well. Experiments were carried out on the experimental rig, and the model was validated using the obtained experimental results. Dynamic simulation was made based on the model to get a 3-D graph of drum level sloshing, which shows a vivid procedure of drum level sloshing. The effect of feed-water flow rate, main-steam flow rate and heating quantity on the drum level sloshing was analyzed. The simulation results indicate that the signals with frequency higher than 0.05 Hz are that of drum level sloshing, the signals with frequency of 0.0-0.05 Hz are that of drum level trendy and "false water level", and variation of the feed-water flow rates, main-steam flow rates and heating quantities can change the frequency of drum level sloshing, i.e., the frequency of sloshing increases with the increase of feed-water flow rate, or the decrease of the main-steam flow rate and the heating quantity. This research work is fundamental to improve signal-to-noise ratio of drum level signal and precise controlling of drum level.展开更多
El Nifio and Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific sea-air interactions. An asymptotic method of solving equations for the ENSO model is proposed. Based on a class...El Nifio and Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific sea-air interactions. An asymptotic method of solving equations for the ENSO model is proposed. Based on a class of oscillator of ENSO model and by employing a simple and valid method of the variational iteration, the coupled system for a sea-air oscillator model of interdecadal climate fluctuations is studied. Firstly, by introducing a set of functionals and computing the variationals, the Lagrange multipliers are obtained. And then, the generalized variational iteration expressions are constructed. Finally, by selecting appropriate initial iteration, and from the iterations expressions, the approximations of solution for the sea-air oscillator ENSO model are solved successively. The approximate dissipative travelling wave solution of equations for corresponding ENSO model is studied. It is proved from the results that the method of the variational iteration can be used for analyzing the sea surface temperature anomaly in the equatorial Pacific of the sea-air oscillator for ENSO model.展开更多
基金Supported by the Natural Science Foundation of Ministry of Education of Jiangsu Province (02KJB470001).
文摘Oscillating heat pipes (OHPs) are very promising cooling devices. Their heat transfer performance is af- fected by many factors, and the form of the relationship between the performance and the factors is complex and non-linear. In this paper, the effects of charging ratio, inclination angle, and heat input and their interaction effects on heat transfer performance of a looped copper-water OHP are analyzed. First, suppose that the relationship between the response and the variables approximates a second-order model. And use the central composite design to arrange the ex- periment. Then, the method of least squares is used to estimate the parameters in the second-order model. Finally, multi- variate variance analysis is used to analyze the model. The results show that the assumption is right, that is to say, the re- lationship is well modeled by a second-order function. Among the three main effect variables, the effect of inclination angle is the most significant, but their interaction effects are not significant. In the range of the considered factors, both the optimum charging ratio and the optimum inclination angle increase as the heating water flow rate increases.
基金Project(531107040300) supported by the Fundamental Research Funds for the Central Universities in ChinaProject(2006BAJ04B04) supported by the National Science and Technology Pillar Program during the Eleventh Five-year Plan Period of China
文摘As for the factors affecting the heat transfer performance of complex and nonlinear oscillating heat pipe (OHP),grey relational analysis (GRA) was used to deal with the relationship between heat transfer rate of a looped copper-water OHP and charging ratio,inner diameter,inclination angel,heat input,number of turns,and the main influencing factors were defined.Then,forecasting model was obtained by using main influencing factors (such as charging ratio,interior diameter,and inclination angel) as the inputs of function chain neural network.The results show that the relative average error between the predicted and actual value is 4%,which illustrates that the function chain neural network can be applied to predict the performance of OHP accurately.
基金Project(2011-0009022) supported by Basic Science Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education,Science and Technology of Korea
文摘The pressure characteristics inside single loop oscillating heat pipe (OHP) having 4.5 mm inner diameter copper tube with the loop height of 440 mm were addressed. Distilled water was used as working fluid inside the OHP with different filling ratios of 40%, 60% and 80% of total inside volume. Experimental results show that the thermal characteristics are significantly inter-related with pressure fluctuations as well as pressure frequency. And the pressure frequency also depends upon the evaporator temperature that is maintained in the range of 60-96 ℃. Piezoresistive absolute pressure sensor (Model-Kistler 4045A5) was used to take data. The investigation shows that the filling ratio of 60% gives the highest inside pressure magnitude at maximum number of pressure frequency at any of set evaporator temperature and the lowest heat flow resistance is achieved at 60% filling ratio.
基金supported by the National Basic Research Program of China[grant number 2014CB953901],support from the National Basic Research Program of China[grant number 2015CB453200]the National Natural Science Foundation of China[grant numbers 41675096,41575043,41375095,and 41505067],the National Natural Science Foundation of China[grant numbers 41475084 and 41630423]
文摘The effects of air-sea coupling over the tropical Indian Ocean(TIO) on the eastward propagating boreal winter intraseasonal oscillation(MJO) are investigated by comparing a fully coupled and a partially decoupled Indian Ocean experiment using the SINTEX-F coupled model.Air-sea coupling over the TIO significantly enhances the intensity of the eastward propagations of the MJO along the5°-10°S zonal areas.The zonal asymmetry of the SST anomaly(SSTA) is responsible for the enhanced eastward propagation.A positive SSTA appears to the east of the MJO convection,which results in the boundary layer moisture convergence and positively feeds back to the MJO convection.In addition,the air-sea interaction effect on the eastward propagation of the MJO is related to the interannual variations of the TIO.Air-sea coupling enhances(reduces) the eastward-propagating spectrum during the negative Indian Ocean dipole mode and positive Indian Ocean basin mode.Such phase dependence is attributed to the role of the background mean westerly in affecting the wind-evaporation-SST feedback.Air-sea coupling(decoupling) enhances(reduces) the zonal asymmetry of the low-level specific humidity,and thus the eastward propagation spectrum of the MJO.
基金Project(51306198)supported by the National Natural Science Foundation of ChinaProject(NR2013K07)supported by Beijing Key Lab of Heating,Gas Supply,Ventilating and Air Conditioning Engineering,China+1 种基金Project(331614013)supported by Beijing University of Civil Engineering and Architecture,ChinaProject(00921915023)supported by Organization Department of Beijing,China
文摘Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop plate oscillating heat pipe with parallel channels(POHP-PC) were experimentally investigated by varying liquid filled ratios(50%, 70%, 85%), section scales(1 mm×1 mm and 1 mm×1.5 mm), inclination angles, working fluids and heating inputs. It was found that during operating there was mixed flow consisting of plug flow and annular flow in channels of oscillating heat pipe at steady-state. There was an equilibrium position for working fluid of condenser during oscillating, and periodic oscillations occurred up and down in the vicinity of equilibrium position. With heat input increasing, equilibrium position rose slowly as a result of vapor pressure of evaporation.Evaporation temperature oscillating amplitude possessed a trend of small-large-small and frequency trend was of small-large during steady-state. It may be generally concluded that temperature, whether evaporator or condenser, fluctuated sharply or rose continuously when oscillating heat pipe coming to dry burning state. Simultaneously, it was found that temperature difference of cooling water possibly dropped with heat input rising during dry burning state. Thermal resistance of No. 2 with acetone was lower than that of No. 1 during experiments, but No. 2 achieving heat transfer limit was earlier than No. 1. However, with ethanol, thermal resistance of No. 1 and No. 2 were similar with the heating input less than 110-120 W and filling ratios of 50% and 70%. And with filling ratio of 85%, heating transfer performance of No. 2 was better compared to No. 1 during all the experiments.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q11-02)
文摘The temporal variations in the frequency of tropical cyclones (TCs) traversing the Taiwan and Hainan Islands (TH islands), were analyzed using a best-track TC dataset from the Joint Typhoon Warning Center for the period 1945-2007. Results show that the oscillations were interannual and interdecadal on the timescales of 2-8 and 8-12 years, respectively. It is also shown that the number of TCs formed in the western North Pacific basin (WNP) and of those traversing the TH islands varied intraseasonally. These results also held for typhoons traversing the TH islands, although the oscillations were less apparent. This study identified interrelationships between the frequency of TCs making landfall on the TH islands and the East Asia summer monsoon (EASM), the South Asia summer monsoon (SASM), and the South China Sea summer monsoon (SCSSM). The SCSSM significantly influenced the number of TCs traversing Hainan Island, but had little influence on the number of TCs traversing Taiwan Island. By contrast, the SASM influenced the numbers of TCs traversing both of the TH islands, shown by correlation coefficients of 0.41 for Taiwan Island and -0.25 for Hainan Island. In addition, the frequency of TC landfall on Taiwan Island increased during years of enhanced EASM, as indicated by a correlation coefficient of 0.4.
基金National Basic Research Program of China(973 Program)(2009CB421503)Natural Science Foundation of China(41075073+2 种基金40775058)Tropical Marine&Meteorologic Science Foundation(201103)Natural Science Foundation of Guangxi(2010GXNSFA013010)
文摘Using the daily average outgoing longwave radiation and NCEP/NCAR reanalysis data in boreal summer(Mays to Octobers)from 1979 to 2007,the propagating characteristics of convection intraseasonal oscillations(ISOs)in the Asian-western Pacific(AWP)region and the relationship between tropical synoptic waves and ISOs are examined by means of finite-domain wavenumber-frequency energy spectrum analysis and lagged linear regression technique.The results are shown as follows.(1)The AWP ISOs propagate both eastward and westward,showing seasonality and regionality.The ISOs propagate eastward with a period of 30 to 60 days over equatorial regions in the whole AWP region,while the westward propagation occurs over 10 to 20°N western Pacific or in the late summers(August,September and October) with periods of 20 to 40 days.The ISOs eastward propagation mainly occurs in primary summers while the westward propagation enhances in late summers.(2)Deep ISO convections associate with westerly and cyclonic circulation anomalies that first form in the Indian Ocean,propagate eastward to the dateline in the Pacific and then turn northwestward.The ISOs convections show northwestward propagating characteristics in the western North Pacific.(3)The ISOs link with the tropical synoptic waves closely.Both convection signals,though with different spatio-temporal scale,enhance simutaneously in the northwestern Pacific,and the ISOs facilitate the forming of a cluster of tropical cyclones(TCs),while a cluster of TCs convection becomes one portion of the northwestward ISOs.
基金The National Natural Science Foundation ofChina (Grant Nos. 90711003 and 40921003)Chinese Coordinated Observation and Prediction of climate System (ChineseCOPES) program (Grant No. GYHY200706005) jointly supportedthis study
文摘This study utilizes a new monthly-assimilated sea temperature and analyzes trend and decadal oscillations in tropical Pacific 100 200 m subsurface ocean temperature (SOT) from 1945 to 2005 on the basis of the harmonic analysis and Empirical Orthogonal Function (EOF) methods.Significant cooling trends in the SOT in the tropical western Pacific were found over this 60-year period.The first EOF of the SOT in tropical Pacific displays an ENSO-like zonal dipole pattern on decadal time scale,and we considered this pattern in subsurface ocean temperature the tropical Pacific decadal oscillation (TPDO).Our analysis suggests that TPDO is closely correlated with the Pacific decadal oscillation (PDO) in the surface sea temperature (SST).The correlation coefficient between the indices of TPDO and PDO is +0.81 and reaches a maximum of +0.84 when TPDO lags behind PDO by 2 months.Therefore,a change of TPDO is likely related to the variation of PDO.The long-term change in TPDO best explains decadal warming in the tropical eastern Pacific SST and implies potential impact on the weakening of East Asian summer monsoons after the late 1970s.
基金National Natural Science Foundation of China under Grant Nos.10335010 and 70431002the Nonlinear Science 973 Project under Grant No.10675020
文摘Gene transcriptional regulation (TR) processes are often described by coupled nonlinear ordinary differential equations (ODEs). When the dimension of TR circuits is high (e.g. n≥3) the motions of the corresponding ODEs may, very probably, show self-sustained oscillations and chaos. On the other hand, chaoticity may be harmful for the normal biological functions of TR processes. In this letter we numerically study the dynamics of 3-gene TR ODEs in great detail, and investigate many 4-, 5-, and lO-gene TR systems by randomly choosing figures and parameters in the conventionally accepted ranges. And we find that oscillations are very seldom and no chaotic motion is observed, even if the dimension of systems is sufficiently high (n≥3). It is argued that the observation of nonchaoticity of these ODEs agrees with normal functions of actual TR processes.
基金Project(NRF-2012R1A1A4A01002052)supported by Basic Science Research Program through the National Research Foundation(NRF)funded by the Ministry of Education,Science and Technology of Korea
文摘Effective thermal performance of oscillating heat pipe(OHP)is driven by inside pressure distribution.Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP charged with aqueous Al2O3 and MWCNTs/Al2O3 nanoparticles.The influences on thermal resistance of aqueous Al2O3,MWCNTs as well as the hybrid of them in OHP having 3 mm in inner diameter were investigated at 60% filling ratio.Experimental results show that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations with time.Frequency of pressure depends upon the power input in evaporative section.A little inclusion of MWCNTs into aqueous Al2O3 at 60% filling ratio achieves the highest fluctuation frequency and the lowest thermal resistance at any evaporator power input though different nanofluids cause different thermal performances of OHPs.
基金sponsored by the Joint Project of Natural Science Foundation of China and Yunnan Province (U0833602)
文摘This paper focuses on the impacts of convective momentum transport(CMT) on simulations of the tropical intraseasonal oscillation(TIO) in SAMIL. Two sets of experiments are performed, which give different reality of the Madden-Julian Oscillation(MJO). The Tiedtke cumulus parameterization scheme is used for all experiments. It is found that simulations of the TIO can be influenced by CMT, and the impacts on the simulated TIO depend on the model capability in simulating the MJO. CMT tends to have large influences to the model that can simulate the eastward propagation of the MJO. CMT can further influence the long-term mean of zonal wind and its vertical shear. Zonal wind suffers from easterlies biases at low level and westerlies biases at upper level when CMT is introduced. Such easterlies biases at low level reduce the reality of the simulated tropical intraseasonal oscillation. When CMT is introduced in the model, MJO signals disappear but the model's mean state improves. Therefore, a more appropriate way is needed to introduce CMT to the model to balance the simulated mean state and TIO signals.
基金Project(531107040300)supported by the Fundamental Research Funds for the Central Universities in ChinaProject(51176045)supported by the National Natural Science Foundation of China
文摘In order to explain the oscillation heat transfer dynamics of closed loop oscillation heat pipe (CLOHP) with two liquid slugs,analysis on the forces and heat transfer process of the partial gas-liquid phase system involving multiple parameters was carried out,and a new type oscillation heat transfer dynamic model of the CLOHP was set up based on conservation laws of mass,momentum and energy.Application results indicate that its oscillation heat transfer dynamics features depend largely on the filling rate,pipe diameter and difference in temperature.Besides,oscillation intensity and transfer performance can be improved to a large extent by increasing the temperature difference properly and enlarging the pipe diameter within a certain range under a certain filling rate.
文摘The heat distributions in the upper layers of the ocean have been studied and some important low frequency oscillations (LFOs) are already found and quantified by using various characteristic factors. In this paper, the ‘heat center' of a sea area is defined with a simple method. Then the temperature data set of the upper layer of the global ocean (from surface down to 400 m, 1955-2003) is analyzed to detect the possible LFOs. Not only some zonal LFOs, which were reported early, but also some strong LFOs of the vertical and meridional heat distribution, which might imply some physical sense, are detected. It should be noted that the similar vertical oscillation pattern can be found in the Pacific Ocean, Atlantic Ocean and Indian Ocean. Results from some preliminary studies show that the vertical LFO might be caused by the solar irradiance anomalies. This study may help reveal some unknown dynamical processes in the global oceans and may also benefit other related studies.
基金jointly supported by the National Key Research and Development Program of China grant number 2017YFA0603903the National Natural Science Foundation of China grant numbers 41622503 and 41775101。
文摘This study evaluates the performance of the Grid-point Atmospheric Model of IAP LASG,version 3(GAMIL3),in simulating the Madden–Julian Oscillation(MJO),based on the CMIP6(phase 6 of the Coupled Model Intercomparison Project)AMIP(Atmospheric Model Intercomparison Project)simulation.Results show that GAMIL3 reasonably captures the main features of the MJO,such as the eastward-propagating signal in the MJO frequency band,the symmetric and asymmetric structures of the MJO,several convectively coupled equatorial waves,and the MJO life cycle.However,GAMIL3 underestimates the MJO amplitude,especially for outgoing longwave radiation,as do most CMIP5 models,and simulates slow eastward propagation.
基金Project(51276023) supported by the National Natural Science Foundation of ChinaProject(09k069) supported by the Open Project Funded by Universities Innovation Platform, Hunan Province, ChinaProject(2011GK311) supported by the Office of Science and Technology of Hunan Province, China
文摘Drum level sloshing is the latest discovery in the application of heat recovery steam generator (HRSG) in combined cycle, and shows certain negative influence on drum level controlling. In order to improve drum level controlling, influence factors on the drum level sloshing were investigated. Firstly, drum sub-modules were developed using the method of modularization modeling, and then the model of drum level sloshing was set up as well. Experiments were carried out on the experimental rig, and the model was validated using the obtained experimental results. Dynamic simulation was made based on the model to get a 3-D graph of drum level sloshing, which shows a vivid procedure of drum level sloshing. The effect of feed-water flow rate, main-steam flow rate and heating quantity on the drum level sloshing was analyzed. The simulation results indicate that the signals with frequency higher than 0.05 Hz are that of drum level sloshing, the signals with frequency of 0.0-0.05 Hz are that of drum level trendy and "false water level", and variation of the feed-water flow rates, main-steam flow rates and heating quantities can change the frequency of drum level sloshing, i.e., the frequency of sloshing increases with the increase of feed-water flow rate, or the decrease of the main-steam flow rate and the heating quantity. This research work is fundamental to improve signal-to-noise ratio of drum level signal and precise controlling of drum level.
基金Under the auspices of National Natural Science Foundation of China (No. 40876010)Main Direction Program of Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-Q03-08)+3 种基金R & D Special Fund for Public Welfare Industry (meteorology) (No.GYHY200806010)LASG State Key Laboratory Special FundFoundation of E-Institutes of Shanghai Municipal Education Commission (No. E03004)Natural Science Foundation of Zhejiang Province (No. Y6090164)
文摘El Nifio and Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific sea-air interactions. An asymptotic method of solving equations for the ENSO model is proposed. Based on a class of oscillator of ENSO model and by employing a simple and valid method of the variational iteration, the coupled system for a sea-air oscillator model of interdecadal climate fluctuations is studied. Firstly, by introducing a set of functionals and computing the variationals, the Lagrange multipliers are obtained. And then, the generalized variational iteration expressions are constructed. Finally, by selecting appropriate initial iteration, and from the iterations expressions, the approximations of solution for the sea-air oscillator ENSO model are solved successively. The approximate dissipative travelling wave solution of equations for corresponding ENSO model is studied. It is proved from the results that the method of the variational iteration can be used for analyzing the sea surface temperature anomaly in the equatorial Pacific of the sea-air oscillator for ENSO model.