Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CP...Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.展开更多
A modified one-dimensional transient hygrothermal model for multilayer wall was proposed using air humidity ratio and temperature as the driving potentials.The solution for the governing equations was obtained numeric...A modified one-dimensional transient hygrothermal model for multilayer wall was proposed using air humidity ratio and temperature as the driving potentials.The solution for the governing equations was obtained numerically by implementing the finite-difference scheme.To evaluate the accuracy of the model,a test system was built up to measure relative humidity and temperature within a porous wall and compare with the prediction of the model.The prediction results have good agreement with the experimental results.For the interface close to indoor side,the maximum deviation of temperature between calculated and test data is 1.87 K,and the average deviation is 0.95 K;the maximum deviation of relative humidity is 11.4%,and the average deviation is 5.7%.For the interface close to outdoor side,the maximum deviation of temperature between prediction and measurement is 1.78 K,and the average deviation is 1.1 K;the maximum deviation of relative humidity is 9.9%,and the average deviation is 4.2%.展开更多
The transmission and distribution of moisture in cement-based materials are of great significance to the properties and durability of materials. Traditional macro-humidity monitoring equipment in civil engineering can...The transmission and distribution of moisture in cement-based materials are of great significance to the properties and durability of materials. Traditional macro-humidity monitoring equipment in civil engineering cannot capture the microscale humidity inside cement-based materials in situ. In this paper, a method of using rhodamine 6G fluorescence to characterize the change in relative humidity in cement-based materials is proposed. Two kinds of moulding processes are designed, which are premixed and smeared after moulding, and the optimal preparation concentration is explored. The results showed that rhodamine 6G can reflect the relative humidity of cement-based materials in situ by its fluorescence intensity and had little effect on the hydration heat release and hydration products of cement-based materials;the fluorescence intensity was much higher when the internal relative humidity was 63% and 75%. The research results lead the application of polymer materials in the field of traditional building materials, help to explore the performance evolution law of cement-based materials in micro scale, and have important significance for the evolution from single discipline to interdisciplinary.展开更多
Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe w...Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe way to control biological contamination was to limit relative humidity in HVAC system and conditioned environment in the range that is more unsuitable for microorganism to survive. In this paper,by referring to bio-clean project experiences,a system-based humidity priority control manner came into being by lowering outdoor air humidity ratio to eliminate all indoor latent load and using self recirculation units to bear indoor sensible load. Based on the whole-course residue humidity contaminant control concept,dynamic step models for coil and conditioned zone were developed to describe mass and energy conservation and transformation processes. Then,HVAC system and conditioned zone dynamic models were established on LabVIEW+Matlab platform to investigate optimized regulation types,input signatures and control logics. Decoupling between cooling and dehumidification processes can be achieved and a more simplified and stable control system can be acquired by the system-based humidity priority control strategy. Therefore,it was a promising way for controlling biological pollution in buildings in order to achieve better IAQ.展开更多
Relative humidity(RH)plays a pivotal role in regulating plant transpiration by modulating stomatal conductance().Accurate modeling under varying RH conditions is essential for predicting plant water use and gas exchan...Relative humidity(RH)plays a pivotal role in regulating plant transpiration by modulating stomatal conductance().Accurate modeling under varying RH conditions is essential for predicting plant water use and gas exchange,with important implications for both agricultural management and bionic applications.In this study,field experiments were conducted to measure in plants exposed to moderate-and high-RH environments.The results demonstrated that is greater and transpiration rates are lower in high-RH environments than in moderate-RH environments.The response functions of stomatal conductance to environmental factors were further developed via a boundary line technique.These functions elucidate how stomatal conductance is correlated with environmental conditions.Specifically,stomatal conductance reaches saturation at a photosynthetically active radiation(PAR)of approximately 300 and 500μmol·m^(−2)·s^(−1) in both high-and moderate-RH environments.Furthermore,the vapor pressure deficit(VPD)threshold triggering stomatal closure was shifted by ambient RH,occurring at approximately 1000 Pa under high RH and 2000 Pa under moderate RH.This RH-dependent adjustment highlights the indirect yet critical role of RH in modulating stomatal sensitivity to atmospheric dryness.On the basis of the established response functions,stomatal conductance models tailored for high-and moderate-RH environments were constructed by extending the Jarvis empirical framework.These models offer improved predictive capacity for simulating plant physiological responses under diverse humidity conditions and provide new insights into the stomatal regulation of plants in natural field settings.展开更多
To explore the effects of relative humidity(RH)on the quality of walnut kernels and establish a rapid,effective method/model for identifying their deterioration degree,walnut kernels were stored at 45℃for 90 days und...To explore the effects of relative humidity(RH)on the quality of walnut kernels and establish a rapid,effective method/model for identifying their deterioration degree,walnut kernels were stored at 45℃for 90 days under different RH conditions(35%,50%,65%and 80%)in this study.Every 15 days,changes in the kernels'color,acid values(AV),peroxide values(POV),fatty acid composition,contents of total phenols and soluble quinones,synchronous fluorescence spectra,and the compositions/contents of volatile organic compounds(VOCs)were analyzed.Partial least squares discriminant analysis(PLS-DA)and variable importance in projection(VIP)were used to conduct differential analysis of VOCs.The deterioration degree of walnut kernels was predicted using Pearson correlation analysis and a Back Propagation Neural Network(BPNN)model.The results showed that RH had a significant effect on the quality of walnut kernels,with 65%RH being the suitable storage condition for them.According to gas chromatography-mass spectrometry(GC-MS)analysis,a total of 40,34,23 and 17 characteristic VOCs were identified in the walnut kernels stored at RH of 35%,50%,65%and 80%,respectively.Among these VOCs,hexanal,1-octen-3-ol,4,5-dimethyltetrahydrofuran-2-one and DL-pantolactone were identified as potential volatile deterioration markers(PVDMs).Based on the POV limit standard of 1.0 mmol/kg for walnut oil,the threshold concentrations of these four PVDMs were 500-1000,50-100,10-15,and 30-60μg/100g,respectively.This research provides a reference for the quality monitoring and evaluation of walnut kernels during storage.展开更多
The hybrid system with radiant cooling and dedicated outdoor air not only possesses high energy efficiency, but also creates a healthy and comfortable indoor environment. Indoor air quality will be improved by the ded...The hybrid system with radiant cooling and dedicated outdoor air not only possesses high energy efficiency, but also creates a healthy and comfortable indoor environment. Indoor air quality will be improved by the dedicated outdoor air system(DOAS) and indoor thermal comfort can be enhanced by the radiant cooling system(RCS). The optimal air-supply mode of the hybrid system and the corresponding design approach were investigated. A full-scale experimental chamber with various air outlets and the ceiling radiant cooling panels(CRCP) was designed and established. The performances of different air-supply modes along with CRCPs were analyzed by multi-index evaluations. Preliminary investigations were also conducted on the humidity stratification and the control effect of different airflow modes to prevent condensation on CRCP. The overhead supply air is recommended as the best combination mode for the hybrid system after comprehensive comparison of the experiment results. The optimal proportion of CRCP accounting for the total cooling capacities in accord with specific cooling loads is found, which may provide valuable reference for the design and operation of the hybrid system.展开更多
To investigate the static compressive properties and mechanical damage evolution of rubber cement-based materials(RCBMs) with dry-and wet-curing conditions, uniaxial compression and cyclic loading-unloading tests were...To investigate the static compressive properties and mechanical damage evolution of rubber cement-based materials(RCBMs) with dry-and wet-curing conditions, uniaxial compression and cyclic loading-unloading tests were carried out on rubber cement mortar(RCM). The mechanical properties of the uniaxial compression specimens cured at 95%(wet-curing) and 50%(dry-curing) relative humidities and cyclic loading-unloading specimens cured at wet-curing were analyzed. Under uniaxial compression, the peak stress loss ratio is higher for dry-curing than for wet-curing. The peak strain decreases with the increase of rubber content, and the peak strain increases with the decrease of curing humidity. Under cyclic loading-unloading, the variation trends of residual strain differences of the normal cement mortar and RCM at each cyclic level with the number of cycles are basically the same, but the failure modes are different. The analysis of the internal mesostructure by a scanning electron microscope(SEM) shows that initial damage is further enhanced by reducing curing humidity and adding rubber aggregate. The damage constitutive model based on strain equivalence principle and statistical theories was used to describe the uniaxial compression characteristics of RCM, and the law of mechanical damage evolution was predicted.展开更多
The character of Sn-Bi plating chips,such as the effect of whisker preventing, solder ability,temperature cycle(T/C) test and thermal humidity bias(THB) test result was introduced.The research result shows that the Sn...The character of Sn-Bi plating chips,such as the effect of whisker preventing, solder ability,temperature cycle(T/C) test and thermal humidity bias(THB) test result was introduced.The research result shows that the Sn-Bi plating chips have good effect of prevent whisker from growing,these chips can pass the T/C test and THB test.展开更多
To relieve the increasing traffic load, many early built highways need to be widened or reconstructed. The rapid performance detection to existing subgrades is important to their reasonable evaluation and maximized ut...To relieve the increasing traffic load, many early built highways need to be widened or reconstructed. The rapid performance detection to existing subgrades is important to their reasonable evaluation and maximized utilization. Based on five kinds of soils taken from an existing highway in southern China, three commonly detecting methods were used to determine their moisture contents, compaction degrees and resilient moduli. The results showed that the measured moisture contents were greater than the design value, and the compaction degrees decreased sharply compared to the original ones. The moisture and heat exchange produced a decrease in the resilient modulus of plate loading test(PLT) from the standard 60 MPa down to 40 MPa. Afterwards, the portable falling weight deflectometer(PFWD) and dynamic cone penetrometer(DCP) were used to evaluate the subgrade performances. The measured PFWD moduli and the DCP penetration rates were correlated with the resilient moduli of PLT, deflections of the Beckman beam test, compaction degrees and moisture contents. The correlation analysis indicates that both of two methods are suitable in rapid detecting subgrade performances, but PFWD method is more recommended for it has higher accuracy and efficiency.展开更多
Due to the fact that the turbine outlet temperature of aeroderivative three-shaft gas turbine is low,the conventional combined cycle is not suitable for three-shaft gas turbines.However,the humid air turbine(HAT)cycle...Due to the fact that the turbine outlet temperature of aeroderivative three-shaft gas turbine is low,the conventional combined cycle is not suitable for three-shaft gas turbines.However,the humid air turbine(HAT)cycle provides a new choice for aeroderivative gas turbine because the humidification process does not require high temperature.Existing HAT cycle plants are all based on single-shaft gas turbines due to their simple structures,therefore converting aeroderivative three-shaft gas turbine into HAT cycle still lacks sufficient research.This paper proposes a HAT cycle model on a basis of an aeroderivative three-shaft gas turbine.Detailed HAT cycle modelling of saturator,gas turbine and heat exchanger are carried out based on the modular modeling method.The models are verified by simulations on the aeroderivative three-shaft gas turbine.Simulation results show that the studied gas turbine with original size and characteristics could not reach the original turbine inlet temperature because of the introduction of water.However,the efficiency still increases by 0.16%when the HAT cycle runs at the designed power of the simple cycle.Furthermore,simulations considering turbine modifications show that the efficiency could be significantly improved.The results obtained in the paper can provide reference for design and analysis of HAT cycle based on multi-shaft gas turbine especially the aeroderivative gas turbine.展开更多
Guilin area is situated in the northeastern part of the Guangxi Zhuang Autonomous Region, 110°9′to 110°42′E and 24°40′to 25°40′N. It has a subtropical monsoon humid climate characterized by sha...Guilin area is situated in the northeastern part of the Guangxi Zhuang Autonomous Region, 110°9′to 110°42′E and 24°40′to 25°40′N. It has a subtropical monsoon humid climate characterized by sharp contrast between dry season and rainy season, with an annual mean temperature of 18.3℃ and precipitation of 1936mm, which coincide with the thresholds of temperature and precipitation for tropical karst.展开更多
Fe3S4 is important magnetic mineral that widely exists in the sediments of lakes and oceans. It can not only instruct reducing environment that contains organic matter and sulfate, but also provide paleomagnetic signa...Fe3S4 is important magnetic mineral that widely exists in the sediments of lakes and oceans. It can not only instruct reducing environment that contains organic matter and sulfate, but also provide paleomagnetic signal for paleoenvironmet research. Simultaneously, as a new type of magnetic material, it causes attention. Because Fe3S4 generally exists as an unstable intermediate, it is stringent in preparation conditions. Although some scholars have conducted on the synthesis experiments of Fe3S4 materials, the research on its stable conditions, formation mechanism and evolution process is not yet depth. Accordingly, defining the stable conditions and revealing evolution law of Fe3S4 nanocrystals have important significance for the determination of environmental conditions and the preparation of pure Fe3S4 nanomaterials.展开更多
Wet bulb globe temperature(WBGT)is a comprehensive index obtained mainly from three parameters:black globe temperature(Tg),wet bulb temperature(Tw),and dry bulb temperature(Ta).While in field observation and numerical...Wet bulb globe temperature(WBGT)is a comprehensive index obtained mainly from three parameters:black globe temperature(Tg),wet bulb temperature(Tw),and dry bulb temperature(Ta).While in field observation and numerical simulation,black globe temperature and wet bulb temperature were not easy to obtain,so WBGT was difficult to measure and calculate directly.In order to solve this problem,air dry bulb temperature,wet bulb temperature,globe temperature,relative humidity,mean air velocity,solar radiation and wet bulb globe temperature were collected during the summer(July)in Guangzhou.Correlation analysis and regression analysis were used to get a simplified method to calculate WBGT.The results showed that dry bulb temperature,relative humidity,solar radiation and WBGT were interrelated to some extent.These three parameters could be used in the simplified method to predict WBGT,and the linear correlation and precision of this model were high.In addition,we used the measured data to verify the simplified method,and the results showed that the error of the calculated value and the measured value was all below 5%,which means the simplified calculating method is feasible and can be used in field observation and simulation research of urban thermal environment.展开更多
基金Project(51408184)supported by the National Natural Science Foundation of ChinaProject(E2017202136)supported by the Natural Science Foundation of Hebei Province,China+1 种基金Project(BSBE2017-05)supported by the Opening Funds of State Key Laboratory of Building Safety and Built Environment and National Engineering Research Center of Building Technology,ChinaProject(QG2018-3)supported by Hebei Provincial Department of Transportation,China
文摘Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.
基金Project(51078127) supported by the National Natural Science Foundation of ChinaProject(JJ201109091631) supported by the Foundation for Young Scientists of Jiangxi Education Department, China
文摘A modified one-dimensional transient hygrothermal model for multilayer wall was proposed using air humidity ratio and temperature as the driving potentials.The solution for the governing equations was obtained numerically by implementing the finite-difference scheme.To evaluate the accuracy of the model,a test system was built up to measure relative humidity and temperature within a porous wall and compare with the prediction of the model.The prediction results have good agreement with the experimental results.For the interface close to indoor side,the maximum deviation of temperature between calculated and test data is 1.87 K,and the average deviation is 0.95 K;the maximum deviation of relative humidity is 11.4%,and the average deviation is 5.7%.For the interface close to outdoor side,the maximum deviation of temperature between prediction and measurement is 1.78 K,and the average deviation is 1.1 K;the maximum deviation of relative humidity is 9.9%,and the average deviation is 4.2%.
基金Project(2018YFD1101002) supported by the National Key R&D Program of ChinaProject(51308405) supported by the National Natural Science Foundation of China。
文摘The transmission and distribution of moisture in cement-based materials are of great significance to the properties and durability of materials. Traditional macro-humidity monitoring equipment in civil engineering cannot capture the microscale humidity inside cement-based materials in situ. In this paper, a method of using rhodamine 6G fluorescence to characterize the change in relative humidity in cement-based materials is proposed. Two kinds of moulding processes are designed, which are premixed and smeared after moulding, and the optimal preparation concentration is explored. The results showed that rhodamine 6G can reflect the relative humidity of cement-based materials in situ by its fluorescence intensity and had little effect on the hydration heat release and hydration products of cement-based materials;the fluorescence intensity was much higher when the internal relative humidity was 63% and 75%. The research results lead the application of polymer materials in the field of traditional building materials, help to explore the performance evolution law of cement-based materials in micro scale, and have important significance for the evolution from single discipline to interdisciplinary.
基金Project(2006BAJ02A10) supported by the National Key Technologies R & D Program of China
文摘Indoor biological contamination and HVAC system secondary contamination problems caused wide public concerns. Biological contamination control will be the next step to achieve better IAQ. The most efficient and safe way to control biological contamination was to limit relative humidity in HVAC system and conditioned environment in the range that is more unsuitable for microorganism to survive. In this paper,by referring to bio-clean project experiences,a system-based humidity priority control manner came into being by lowering outdoor air humidity ratio to eliminate all indoor latent load and using self recirculation units to bear indoor sensible load. Based on the whole-course residue humidity contaminant control concept,dynamic step models for coil and conditioned zone were developed to describe mass and energy conservation and transformation processes. Then,HVAC system and conditioned zone dynamic models were established on LabVIEW+Matlab platform to investigate optimized regulation types,input signatures and control logics. Decoupling between cooling and dehumidification processes can be achieved and a more simplified and stable control system can be acquired by the system-based humidity priority control strategy. Therefore,it was a promising way for controlling biological pollution in buildings in order to achieve better IAQ.
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000046).
文摘Relative humidity(RH)plays a pivotal role in regulating plant transpiration by modulating stomatal conductance().Accurate modeling under varying RH conditions is essential for predicting plant water use and gas exchange,with important implications for both agricultural management and bionic applications.In this study,field experiments were conducted to measure in plants exposed to moderate-and high-RH environments.The results demonstrated that is greater and transpiration rates are lower in high-RH environments than in moderate-RH environments.The response functions of stomatal conductance to environmental factors were further developed via a boundary line technique.These functions elucidate how stomatal conductance is correlated with environmental conditions.Specifically,stomatal conductance reaches saturation at a photosynthetically active radiation(PAR)of approximately 300 and 500μmol·m^(−2)·s^(−1) in both high-and moderate-RH environments.Furthermore,the vapor pressure deficit(VPD)threshold triggering stomatal closure was shifted by ambient RH,occurring at approximately 1000 Pa under high RH and 2000 Pa under moderate RH.This RH-dependent adjustment highlights the indirect yet critical role of RH in modulating stomatal sensitivity to atmospheric dryness.On the basis of the established response functions,stomatal conductance models tailored for high-and moderate-RH environments were constructed by extending the Jarvis empirical framework.These models offer improved predictive capacity for simulating plant physiological responses under diverse humidity conditions and provide new insights into the stomatal regulation of plants in natural field settings.
基金Anhui Province Scientific and Technological Research Project(202423110050025)National Key Research and Development Project(2023YFD2100400)。
文摘To explore the effects of relative humidity(RH)on the quality of walnut kernels and establish a rapid,effective method/model for identifying their deterioration degree,walnut kernels were stored at 45℃for 90 days under different RH conditions(35%,50%,65%and 80%)in this study.Every 15 days,changes in the kernels'color,acid values(AV),peroxide values(POV),fatty acid composition,contents of total phenols and soluble quinones,synchronous fluorescence spectra,and the compositions/contents of volatile organic compounds(VOCs)were analyzed.Partial least squares discriminant analysis(PLS-DA)and variable importance in projection(VIP)were used to conduct differential analysis of VOCs.The deterioration degree of walnut kernels was predicted using Pearson correlation analysis and a Back Propagation Neural Network(BPNN)model.The results showed that RH had a significant effect on the quality of walnut kernels,with 65%RH being the suitable storage condition for them.According to gas chromatography-mass spectrometry(GC-MS)analysis,a total of 40,34,23 and 17 characteristic VOCs were identified in the walnut kernels stored at RH of 35%,50%,65%and 80%,respectively.Among these VOCs,hexanal,1-octen-3-ol,4,5-dimethyltetrahydrofuran-2-one and DL-pantolactone were identified as potential volatile deterioration markers(PVDMs).Based on the POV limit standard of 1.0 mmol/kg for walnut oil,the threshold concentrations of these four PVDMs were 500-1000,50-100,10-15,and 30-60μg/100g,respectively.This research provides a reference for the quality monitoring and evaluation of walnut kernels during storage.
基金Project(51178298)supported by the National Natural Science Foundation of China
文摘The hybrid system with radiant cooling and dedicated outdoor air not only possesses high energy efficiency, but also creates a healthy and comfortable indoor environment. Indoor air quality will be improved by the dedicated outdoor air system(DOAS) and indoor thermal comfort can be enhanced by the radiant cooling system(RCS). The optimal air-supply mode of the hybrid system and the corresponding design approach were investigated. A full-scale experimental chamber with various air outlets and the ceiling radiant cooling panels(CRCP) was designed and established. The performances of different air-supply modes along with CRCPs were analyzed by multi-index evaluations. Preliminary investigations were also conducted on the humidity stratification and the control effect of different airflow modes to prevent condensation on CRCP. The overhead supply air is recommended as the best combination mode for the hybrid system after comprehensive comparison of the experiment results. The optimal proportion of CRCP accounting for the total cooling capacities in accord with specific cooling loads is found, which may provide valuable reference for the design and operation of the hybrid system.
基金Projects(52008003,52074009)supported by the National Natural Science Foundation of ChinaProject(201904a07020081)supported by the Key Research and Development Program Project of Anhui Province,ChinaProject(1908085QE213)supported by the Nature Science Foundation of Anhui Province,China。
文摘To investigate the static compressive properties and mechanical damage evolution of rubber cement-based materials(RCBMs) with dry-and wet-curing conditions, uniaxial compression and cyclic loading-unloading tests were carried out on rubber cement mortar(RCM). The mechanical properties of the uniaxial compression specimens cured at 95%(wet-curing) and 50%(dry-curing) relative humidities and cyclic loading-unloading specimens cured at wet-curing were analyzed. Under uniaxial compression, the peak stress loss ratio is higher for dry-curing than for wet-curing. The peak strain decreases with the increase of rubber content, and the peak strain increases with the decrease of curing humidity. Under cyclic loading-unloading, the variation trends of residual strain differences of the normal cement mortar and RCM at each cyclic level with the number of cycles are basically the same, but the failure modes are different. The analysis of the internal mesostructure by a scanning electron microscope(SEM) shows that initial damage is further enhanced by reducing curing humidity and adding rubber aggregate. The damage constitutive model based on strain equivalence principle and statistical theories was used to describe the uniaxial compression characteristics of RCM, and the law of mechanical damage evolution was predicted.
文摘The character of Sn-Bi plating chips,such as the effect of whisker preventing, solder ability,temperature cycle(T/C) test and thermal humidity bias(THB) test result was introduced.The research result shows that the Sn-Bi plating chips have good effect of prevent whisker from growing,these chips can pass the T/C test and THB test.
基金Project(2017YFC0805307) supported by the National Key Research and Development Program of ChinaProjects(51878078, 51927814, 51911530215) supported by the National Natural Science Foundation of China+4 种基金Project(2018-025) supported by the Training Program for High-level Technical Personnel in Transportation Industry, ChinaProject (2018JJ1026) supported by the Excellent Youth Foundation of Natural Science Foundation of Hunan Province, ChinaProject(17A008) supported by the Key Project of Education Department of Hunan Province, ChinaProjects(kfj150103, kfj170104) supported by the Open Research Fund of State Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, ChinaProject(CX20190644) supported by the Postgraduate Scientific Research Innovation Project of Hunan Province, China。
文摘To relieve the increasing traffic load, many early built highways need to be widened or reconstructed. The rapid performance detection to existing subgrades is important to their reasonable evaluation and maximized utilization. Based on five kinds of soils taken from an existing highway in southern China, three commonly detecting methods were used to determine their moisture contents, compaction degrees and resilient moduli. The results showed that the measured moisture contents were greater than the design value, and the compaction degrees decreased sharply compared to the original ones. The moisture and heat exchange produced a decrease in the resilient modulus of plate loading test(PLT) from the standard 60 MPa down to 40 MPa. Afterwards, the portable falling weight deflectometer(PFWD) and dynamic cone penetrometer(DCP) were used to evaluate the subgrade performances. The measured PFWD moduli and the DCP penetration rates were correlated with the resilient moduli of PLT, deflections of the Beckman beam test, compaction degrees and moisture contents. The correlation analysis indicates that both of two methods are suitable in rapid detecting subgrade performances, but PFWD method is more recommended for it has higher accuracy and efficiency.
基金Project(2017YFB0903300)supported by the National Key R&D Program of ChinaProject(2016M601593)supported by the China Postdoctoral Science Foundation
文摘Due to the fact that the turbine outlet temperature of aeroderivative three-shaft gas turbine is low,the conventional combined cycle is not suitable for three-shaft gas turbines.However,the humid air turbine(HAT)cycle provides a new choice for aeroderivative gas turbine because the humidification process does not require high temperature.Existing HAT cycle plants are all based on single-shaft gas turbines due to their simple structures,therefore converting aeroderivative three-shaft gas turbine into HAT cycle still lacks sufficient research.This paper proposes a HAT cycle model on a basis of an aeroderivative three-shaft gas turbine.Detailed HAT cycle modelling of saturator,gas turbine and heat exchanger are carried out based on the modular modeling method.The models are verified by simulations on the aeroderivative three-shaft gas turbine.Simulation results show that the studied gas turbine with original size and characteristics could not reach the original turbine inlet temperature because of the introduction of water.However,the efficiency still increases by 0.16%when the HAT cycle runs at the designed power of the simple cycle.Furthermore,simulations considering turbine modifications show that the efficiency could be significantly improved.The results obtained in the paper can provide reference for design and analysis of HAT cycle based on multi-shaft gas turbine especially the aeroderivative gas turbine.
文摘Guilin area is situated in the northeastern part of the Guangxi Zhuang Autonomous Region, 110°9′to 110°42′E and 24°40′to 25°40′N. It has a subtropical monsoon humid climate characterized by sharp contrast between dry season and rainy season, with an annual mean temperature of 18.3℃ and precipitation of 1936mm, which coincide with the thresholds of temperature and precipitation for tropical karst.
基金Supported by National Natural Science Foundation (Grant No.:40872045 41172047)The Opening Project of Key Laboratory of Solid Waste Treatment and Resource Recycle (SWUST), Ministry of Education (12zxgk01)
文摘Fe3S4 is important magnetic mineral that widely exists in the sediments of lakes and oceans. It can not only instruct reducing environment that contains organic matter and sulfate, but also provide paleomagnetic signal for paleoenvironmet research. Simultaneously, as a new type of magnetic material, it causes attention. Because Fe3S4 generally exists as an unstable intermediate, it is stringent in preparation conditions. Although some scholars have conducted on the synthesis experiments of Fe3S4 materials, the research on its stable conditions, formation mechanism and evolution process is not yet depth. Accordingly, defining the stable conditions and revealing evolution law of Fe3S4 nanocrystals have important significance for the determination of environmental conditions and the preparation of pure Fe3S4 nanomaterials.
基金Supported by the National Natural Science Foundation of China(50538040,50720165805,50808083)the 111 project(111-2-13)State Key Laboratory of Subtropical Building(2008ZB14)
文摘Wet bulb globe temperature(WBGT)is a comprehensive index obtained mainly from three parameters:black globe temperature(Tg),wet bulb temperature(Tw),and dry bulb temperature(Ta).While in field observation and numerical simulation,black globe temperature and wet bulb temperature were not easy to obtain,so WBGT was difficult to measure and calculate directly.In order to solve this problem,air dry bulb temperature,wet bulb temperature,globe temperature,relative humidity,mean air velocity,solar radiation and wet bulb globe temperature were collected during the summer(July)in Guangzhou.Correlation analysis and regression analysis were used to get a simplified method to calculate WBGT.The results showed that dry bulb temperature,relative humidity,solar radiation and WBGT were interrelated to some extent.These three parameters could be used in the simplified method to predict WBGT,and the linear correlation and precision of this model were high.In addition,we used the measured data to verify the simplified method,and the results showed that the error of the calculated value and the measured value was all below 5%,which means the simplified calculating method is feasible and can be used in field observation and simulation research of urban thermal environment.
