A theoretical model of a humidifier of proton exchange membrane （PEM） fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the...A theoretical model of a humidifier of proton exchange membrane （PEM） fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the system is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. The experimental data acquired from the test bench are used for identification. The one-step-ahead predictions and the five-step-ahead predictions are compared with the real measurements, respectively. It shows that the identified model can effectively describe the real system.展开更多
The work presents a parametric analysis of the performance of a solar-driven thermoelectric system to dehumidify air and produce fresh water. The system is combined with a solar distiller humidifying ambient air to en...The work presents a parametric analysis of the performance of a solar-driven thermoelectric system to dehumidify air and produce fresh water. The system is combined with a solar distiller humidifying ambient air to enhance distillate output to meet the specified fresh water needs for a residential application. The presented system is a totally renewable energy-based system taking advantage of the clean solar energy. A model is developed to simulate the air dehumidification process using TEC （thermoelectrically cooled） channels. An optimization problem for setting system operational parameters is formulated to meet the fresh water requirement of 10 liters per day for a typical residential application in the Lebanese coastal humid climate. Using five TEC channels of length of 1.2 m and area of 0.07 - 0.05 m^2 integrated with 1.2 m^2 solar distiller is capable of meeting the water demand, where the air mass flow rate introduced to each TEC channel is optimally set at 0.0155 kg/s. The optimal electrical current input to the TEC modules from the photovoltaic solar panels varied depending on the month and is set at 2.2 A in June, 2.1 A in July and 2.0 A in August, September and October per each TEC module.展开更多
The perfect combination of renewable energy and desalination technologies is the key to meeting water demands in a cost-effective,efficient and environmentally friendly way.The desalination technique by humidification...The perfect combination of renewable energy and desalination technologies is the key to meeting water demands in a cost-effective,efficient and environmentally friendly way.The desalination technique by humidificationdehumidification is non-conventional approach suitable for areas with low infrastructure(such as rural and decentralized regions)since it does not require permanent maintenance.In this study,this technology is implemented by using solar energy as a source of thermal power.A seawater desalination unit is considered,which consists of a chamber with two evaporators(humidifiers),a wetted porous material made of a corrugated cellulose cardboard and a condenser(dehumidifier).The evaporation system is tested with dry bulb temperature and relative air humidity data.The results of numerical simulations indicate that higher inlet air velocities(from 0.75 to 3 m/s)lead to a decrease in theΔT,ΔRH,and effectiveness.With the air remaining within the evaporator for 30 cm,the temperature differential increases to 5.7°C,accompanied by a 39%rise in relative humidity contrast.These changes result in a significant enhancement in humidification efficiency,achieving a remarkable efficiency level of 78%.However,a wettability value of 630 m^(2)/m^(3)leads to a smaller reduction of these parameters.Increasing the pad thickness,particularly to 0.3 m,improves performance by boostingΔT,ΔRH,and effectiveness,especially for pads with a wettability of 630 m^(2)/m^(3),for which superior performances are predicted by the numerical tests.展开更多
The Tibetan Plateau(TP),known as the“Third Pole of Earth”,and its ecosystem is quite sensitive to climate change(Yao et al.,2012;Qiu,2008).In recent decades,the main TP has experienced warming and humidification(alt...The Tibetan Plateau(TP),known as the“Third Pole of Earth”,and its ecosystem is quite sensitive to climate change(Yao et al.,2012;Qiu,2008).In recent decades,the main TP has experienced warming and humidification(although there has been a drying trend in the southern region),and researchers anticipate that this change will continue in the future(Jiang et al.,2023;Sun et al.,2020;Chen et al.,2015).展开更多
Hydrophilicity is critical in Nafion membranes during fuel cell operation as insufficient membrane hydration leads to brittle behavior and a drop in proton conductivity.The incorporation of APTS(3-(aminopro pyl)trieth...Hydrophilicity is critical in Nafion membranes during fuel cell operation as insufficient membrane hydration leads to brittle behavior and a drop in proton conductivity.The incorporation of APTS(3-(aminopro pyl)triethoxysilane)into exfoliated graphene oxide(EGO)by covalent functionalization to be used as filler into Nafion membranes allows higher hydrophilicity for these membranes.This is associated with promoting hydroxyl,carbonyl,siloxane,silane,and amine groups within the EGO-APTS matrix.The incorporation of these materials as Fuel Cell MEAs leads to a significant reduction of the ohmic resistance measured at high frequency resistance(HFR)in electrochemical impedance spectroscopy(EIS)experiments and achieves maximum power densities of 1.33 W cm^(-2)at 60℃ at 100%RH(APTS-EGO,0.2 wt%)and1.33 W cm^(-2)at 60℃ at 70%RH(APTS-EGO,0.3 wt%),which represents an improvement of 190%compared to the commercial Nafion 212 when utilizing low humidification conditions(70%).Moreover,the as-synthesized membrane utilizes lower Nafion ionomer mass,which,in conjunction with the excellent cell performance,has the potential to decrease the cost of the membrane from 87 to 80￡/W as well as a reduction of fluorinated compounds within the membrane.展开更多
Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and...Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and utilize saturated atmospheric water such as fog, dew and condensed water. So far, however, there have been few studies on the aerial parts of desert plants in their absorption of unsaturated water from the atmosphere. This study presents an ultrasonic humidification fluorescent tracing method of detecting unsaturated atmospheric water absorption by the aerial parts of desert plants. We constructed an organic glass room based on the sizes of field plants. Then, the aboveground parts of the plants were humidified in the sealed glasshouse using an ultrasonic humidifier containing fluorescent reagents. The humidity and wetting time were controlled by turning on or off the humidifier according to the reading of a thermo-hygrometer suspended in the glasshouse. Fluorescence microscopy was employed to observe these plant samples. This method can generate unsaturated atmospheric water vapor and incorporate other fluorescent reagents or water-soluble chemical reagents for gasified humidification. In addition, it can identify plant parts that absorb unsaturated atmospheric water from the air, detect water absorption sites on the surface of leaves or tender stems, and determine the ability of tissues or microstructure of aerial parts to absorb water. This method provides a direct visual evidence for the inspection of leaf or tender stem microstructure in response to unsaturated atmospheric water absorption. Moreover, this method shows that aqueous pores in the cuticles of leaves or tender stems of desert plants are large enough to allow the passage of ionic fluorescent brightener with a molecular weight of up to 917 g/mol. Thus, this paper provides an important approach that explores the mechanism by which desert plants utilize unsaturated atmospheric water.展开更多
A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several...A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several operating conditions on the productivity and thermal efficiency of the column were investigated. The results show that both the productivity and thermal efficiency of the column enhance with the elevation of the inlet water temperature. The flow rates of water and carrier gas both have optimal operating ranges, which are 10-30 kg·h^-1 and 4-7kg·h^-1 for the present column, respectively. Meanwhile, the increase of external steam flow rate will promote the productivity of the column but reduce its thermal efficiency.展开更多
Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water t...Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water temperature and large water flow are needed. The water temperature is the most sensitive parameter to the humidification tower. And it is better for the humidification tower to work at temperature higher than 523 K when the system pressure is higher than 5 MPa. The comparison between the model used in this paper and ideal model shows that the ideal model can be used in simulation to simply the calculation when the temperature is lower than 473 K and pressure is lower than 5 MPa.展开更多
Solar humidification-dehumidification desalination technology has been reviewed in detail in this paper. This review would also throw light on the scope for further research and recommendations in active distillation ...Solar humidification-dehumidification desalination technology has been reviewed in detail in this paper. This review would also throw light on the scope for further research and recommendations in active distillation system by humidification and dehumidification (HDH). Also in this article, a review has been done on different types of (HDH) systems. Thermal modeling was done for various types of humidification and dehumidification(HDH) distillation system. From the present review, it is found that the humidification-dehumidification desalination process HDH will be a suitable choice for fresh water production when the demand is decentralized. HDH is a low temperature process where total required thermal energy can be obtained from solar energy. Capacity of HDH units is between that produced by conventional methods and solar stills. Moreover, HDH is distinguished by simple operation and maintenance. Also from the present condensed review, it was observed that an increase in evaporator and condenser surface areas significantly improves system productivity. But prior to implementing any techniques in design improvement, it is necessary to optimize the MEH unit by optimizing its component size to understand the effect of feed water and air flow rates. Although a fair amount of simulation studies have been conducted in the past, further design simulation is required to fully understand the complicated effects of air and water flow rates, the optimum size of individual components or modules of the unit and to generate a comprehensive model for the system.展开更多
A parameter, known as the parameter of humidification vibration deformation, was proposed, describing quantitatively the impact of water content on vibration settlement deformation, and its relationship with humidific...A parameter, known as the parameter of humidification vibration deformation, was proposed, describing quantitatively the impact of water content on vibration settlement deformation, and its relationship with humidification water content, dynamic shear stress peak value, initial consolidation stress and vibration frequency was built. The result shows that 1） the parameter of humidification vibration deformation increases with the vibration shear stress peak value increasing. 2） The humidification water content has significant influence on the curve of the parameter of humidification vibration deformation and the peak vibration shear stress. When the humidification water content is low, the curve increases slowly. However, when the humidification water content is high, the curve increases rapidly. 3） Initial consolidation stress has significant influence on the humidification vibration deformation coefficient. When initial consolidation stress is not large enough to destroy the loess structure, with initial consolidation stress increasing, the humidification vibration deformation coefficient decreases. On the contrary, the humidification vibration deformation coefficient increases with initial consolidation stress increasing. 4） With the increase of vibration time, the parameter of humidification vibration settlement shows an increasing trend overall. The initial dynamic shear stress peak value and humidification water content all have significant effects on the curve of the parameter of humidification vibration settlement and vibration time. However, the humidification water content is even more significant.展开更多
[Objective] This study aimed to analyze the evolution characteristics and occurrence patterns of droughts and floods in Weifang City. [Method] Based on the monthly precipitation data during 1961-2010 obtained from nin...[Objective] This study aimed to analyze the evolution characteristics and occurrence patterns of droughts and floods in Weifang City. [Method] Based on the monthly precipitation data during 1961-2010 obtained from nine meteorological sta- tions of Weifang City, by using standardized precipitation index, monthly SPI index of Weifang City during the past 50 years was calculated to analyze the spatial and temporal distribution characteristics of drought and humidification in Weifang City. [Result] The results showed that the variation of drought and humidification had stage characteristics in Weifang City, which was relatively humid in the 1960s and 1970s and developed from extremely humid in early 1960s to dry in late 1970s, persistent drought was observed throughout the range of Weifang City in the 1980s, and the variation tended to be smooth during the 1990s-2000s. Spatial distribution of drought and humidification in Weifang City showed certain regional characteristics. In the 1960s, the mid-west region of Weifang City was relatively humid, while the southeastern region was relatively dry; in the 1970s, there was little difference among the drought and humidification extent in each region; in the 1980s, each region of Weifang City was generally dry, specifically, drought in the southeastern region was the most severe, while drought in the northern region was the slightest; in the 1990s and 2000s, variation of drought and humidification in each region of Weifang City was basically the same. The uneven spatial and temporal distribution of precipi- tation led to abnormal distribution of drought and humidification in some areas, such as the abnormal phenomenon in 1999; the spatial distribution of drought and humidi- fication duration in each generation had their own characteristics, which brought diffi- culties to the unified deployment of drought and flood control departments. [Conclu- sion] This study provided theoretical basis for the drought resistance, waterlogging prevention and disaster reduction in Weifang City under the background of climate change.展开更多
Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution ...Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution characteristics, and analyzes the mass concentration and the particulate number concentration distribution of different sizes of particulates with time under each condition of the purified water humidification, the tap water humidification and the cold boiled water humidification in the office. The results show that under the three kinds of wetting conditions, the concentration of the fine particulates is higher. More minerals are contained in the tap water and the cold boiled water, so the two kinds of humidification have more significant impact on indoor particulate matter. But the purified water humidification has nearly no significant effect on it. The calcium and magnesium ionic compounds are partly removed after the water boiled, so the cold boiled water humidification has less impact on the indoor particulate matter than the tap water humidification. The mass concentration and particulate number concentration of the particle may also be affected due to the frequency of ultrasonic vibration.展开更多
The polypropylene tubes with surface modification were installed in a baffled shell-tube column to conduct the thermally coupled humidification and dehumidification desalination process. The effects of several operati...The polypropylene tubes with surface modification were installed in a baffled shell-tube column to conduct the thermally coupled humidification and dehumidification desalination process. The effects of several operating parameters （feed water temperature, water flow rate, carrier air flow rate, and external steam flow rate） on the productivity and thermal efficiency of this column were investigated experimentally. The results show that the feed water temperature has a positive effect on the productivity and thermal efficiency, while the flow rates of external steam, feed water, and carrier air should be optimized within the ranges of 0.006-0.020 kg·m^-2·s^-1 , 0.005-0.015 kg·m^-2·s^-1, and 0.7-1.3kg·m^-2·s^-1, respectively; the flow rates of feed water and carrier air are greatly controlled by the wetting state of the tubes. In comparison with the previous desalination column installing the coppery tubes, the present column can reach nearly the same production capacity of distilled water, which demonstrates the feasibility of applying such a plastic column to the humidification and dehumidification desalination process.展开更多
Background:Bird nests are an important part of avian ecology.They are a powerful tool for studying not only the birds that built them,but a wide array of topics ranging from parasitology,urbanisation and climate chang...Background:Bird nests are an important part of avian ecology.They are a powerful tool for studying not only the birds that built them,but a wide array of topics ranging from parasitology,urbanisation and climate change to evolu-tion.Despite this,bird nests tend to be underrepresented in natural history collections,a problem that should be redressed through renewed focus by collecting institutions.Methods:Here we outline the history and current best practice collection and curatorial methods for the nest col-lection of the Australian National Wildlife Collection(ANWC).We also describe an experiment conducted on nests in the ANWC using ultrasonic humidification to restore the shape of nests damaged by inappropriate storage.Results:The experiment showed that damaged nests can be successfully reshaped to close to their original dimen-sions.Indeed,restored nests were significantly closer to their original shape than they were prior to restoration.Thus,even nests damaged by years of neglect may be fully incorporated into active research collections.Best practice techniques include extensive note taking and photography in the field,subsampling of nests that cannot or should not be collected,appropriate field storage,metadata management,and prompt treatment upon arrival at the collec-tion facility.Conclusions:Renewed focus on nest collections should include appropriate care and restoration of current col-lections,as well as expansion to redress past underrepresentation.This could include collaboration with researchers studying or monitoring avian nesting ecology,and nest collection after use in bird species that rebuild anew each nesting attempt.Modern expansion of museum nest collections will allow researchers and natural history collections to fully realise the scientific potential of these complex and beautiful specimens.展开更多
This paper introduced a novel self-adjustment of parameters of fuzzy neural networks. Then, the effects of cathode humidification temperature and anode flow rate on the performance of direct methanol fuel celI（DMFC）...This paper introduced a novel self-adjustment of parameters of fuzzy neural networks. Then, the effects of cathode humidification temperature and anode flow rate on the performance of direct methanol fuel celI（DMFC） were described respectively. Two dynamic performance models of DMFC under the influences of cathode humidification temperature and anode flow rate were established separately based on fuzzy neural networks. The simulation results show the accuracy of the models established is satisfactory.展开更多
Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and m...Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and maxillofacial surgery with tracheal intubation, continuous infusion can be adjusted to the wet method;according to the wet pipe, insertion depth of the flow rate is divided into four groups, by four different depths and velocities of the wetting effect, to be analyzed. Results: B group was significantly lower than other groups satisfied with indicators of four significantly different effects of humidification. Conclusion: When continuous humidification tube insertion depth of endotracheal intubation is 10 - 12 cm, and flow rate is 15 - 20 ml/h, the wetting effect will achieve greater satisfaction.展开更多
In making the gas-solid-liquid phase analysis, based on the collaborative study of the internal and external humidification ratio of desulfurization efficiency, determine the humidifier ratio within 60% to 75%, that c...In making the gas-solid-liquid phase analysis, based on the collaborative study of the internal and external humidification ratio of desulfurization efficiency, determine the humidifier ratio within 60% to 75%, that can make the best balance between the respective merits of a simple tower humidifiers tower humidifier way, optimizing the overall desulfurization reaction, effectively reducing the sticky wall, stick in the desulfurization efficiency and reduce the wall to achieve a balance between the balance, without increasing the sorbent and process water, under the premise can promote the desulfurization reaction, improve the desulfurization sorbent utilization and efficiency, help desulfurization reaction system is stable, efficient and economic operation, the gas-liquid-solid three-phase to achieve better synergy.展开更多
Most of the desalination technologies consume a huge quantity of energy resulting from petroleum products in the form of heat or electrical energy. Solar desalination is a promisingly sustainable freshwater production...Most of the desalination technologies consume a huge quantity of energy resulting from petroleum products in the form of heat or electrical energy. Solar desalination is a promisingly sustainable freshwater production technology. Solar desalination humidification dehumidification process showed the best approach as it is of the highest overall energy efficiency. In this review paper, a detailed study of the previous work is performed on solar humidification dehumidification desalination techniques experimentally and theoretically. Also in this review, different types of HDH systems were mentioned. The review showed that the humidification dehumidification desalination systems are suitable for decentralized demand. On the other hand, capacity of HDH units is not as large as conventional methods or small as solar stills. Finally, this study threw light on the scope of the parameters which have a considerable influence on increasing the freshwater output of the HDH systems as feed water flow rate, air flow rate, and design of the evaporator, condenser, and packing material. A brief economical study and a comparison of the costs per liter are performed for various humidification dehumidification desalination systems presented in this study.展开更多
Recent climate change has accelerated the global hydrological cycle, substantially affecting drought metrics such as drought duration and drought propagation;however, knowledge of drought patterns in these metrics rem...Recent climate change has accelerated the global hydrological cycle, substantially affecting drought metrics such as drought duration and drought propagation;however, knowledge of drought patterns in these metrics remains limited. Here, we aimed to address the evolution and influencing factors of major drought metrics under past and future climate scenarios within the Yellow River Basin(YRB) based on Coupled Model Intercomparison Project Phase 6(CMIP6). Accordingly, we investigated the changes in drought duration for meteorological drought and agricultural drought across the YRB and identified the variability in drought propagation time from meteorological drought to agricultural drought by using a standardized precipitation/soil moisture index and run theory. Meteorological and agricultural drought duration, and propagation time, increased from 1850 to 2014, decreased significantly from 2015 to 2100 with change trends of –0.0027, –0.0197, and –0.002 month/year, respectively. Drought duration had a negative sensitivity to humidification, and agricultural drought was more sensitive than meteorological drought. Propagation time exhibited a greater sensitivity to meteorological humidification than agricultural humidification. The results also suggest that precipitation, evapotranspiration, and soil moisture are the main drivers of drought metric changes, with air temperature and crop cover exhibiting a strong indirect effect on drought metrics in the YRB. Decreased propagation time from meteorological to agricultural drought and decreased duration provide evidence for the accelerated occurrence and increased impact of drought, highlighting the importance of a more comprehensive understanding of drought metric changes under rapid climate change.展开更多
The drylands on the Qinghai–Xizang Plateau are extremely sensitive to climate change and grazing activities.However,there is a lack of quantitative study of the combined effects of aridity and grazing pressure,which ...The drylands on the Qinghai–Xizang Plateau are extremely sensitive to climate change and grazing activities.However,there is a lack of quantitative study of the combined effects of aridity and grazing pressure,which are vital in determining the sustainable grazing areas.In this study,a 2-dimensional threshold model was employed to assess the maximum allowable grazing pressure and determine the sustainable grazing areas under both historical conditions and projected climate change scenarios up to 2100.Results showed that 62.2%of the drylands under historical condition were unsuitable for grazing and 6.7%exceeded the ecological threshold,while 31.1%fell within the areas with sustainable grazing.Model projections indicate a trend toward humidification across the drylands under the climate change scenarios of RCP 4.5 and RCP 8.5.This process is expected to partially alleviate the negative impact of grazing,leading to an expansion of sustainable grazing areas to approximately 41.0%by 2100.These findings provide valuable insights for optimizing grazing strategies in the drylands of the Qinghai–Xizang Plateau in the future.展开更多
基金supported by the Young Scholars Developing Fund of Tangshan Teacher’s College (No.06D06)the Doctoral Fund of the Schoolthe Outstanding Overseas Chinese Scholars Fund of Chinese Academy of Sciences (No.2003-1-10)
文摘A theoretical model of a humidifier of proton exchange membrane （PEM） fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the system is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. The experimental data acquired from the test bench are used for identification. The one-step-ahead predictions and the five-step-ahead predictions are compared with the real measurements, respectively. It shows that the identified model can effectively describe the real system.
文摘The work presents a parametric analysis of the performance of a solar-driven thermoelectric system to dehumidify air and produce fresh water. The system is combined with a solar distiller humidifying ambient air to enhance distillate output to meet the specified fresh water needs for a residential application. The presented system is a totally renewable energy-based system taking advantage of the clean solar energy. A model is developed to simulate the air dehumidification process using TEC （thermoelectrically cooled） channels. An optimization problem for setting system operational parameters is formulated to meet the fresh water requirement of 10 liters per day for a typical residential application in the Lebanese coastal humid climate. Using five TEC channels of length of 1.2 m and area of 0.07 - 0.05 m^2 integrated with 1.2 m^2 solar distiller is capable of meeting the water demand, where the air mass flow rate introduced to each TEC channel is optimally set at 0.0155 kg/s. The optimal electrical current input to the TEC modules from the photovoltaic solar panels varied depending on the month and is set at 2.2 A in June, 2.1 A in July and 2.0 A in August, September and October per each TEC module.
文摘The perfect combination of renewable energy and desalination technologies is the key to meeting water demands in a cost-effective,efficient and environmentally friendly way.The desalination technique by humidificationdehumidification is non-conventional approach suitable for areas with low infrastructure(such as rural and decentralized regions)since it does not require permanent maintenance.In this study,this technology is implemented by using solar energy as a source of thermal power.A seawater desalination unit is considered,which consists of a chamber with two evaporators(humidifiers),a wetted porous material made of a corrugated cellulose cardboard and a condenser(dehumidifier).The evaporation system is tested with dry bulb temperature and relative air humidity data.The results of numerical simulations indicate that higher inlet air velocities(from 0.75 to 3 m/s)lead to a decrease in theΔT,ΔRH,and effectiveness.With the air remaining within the evaporator for 30 cm,the temperature differential increases to 5.7°C,accompanied by a 39%rise in relative humidity contrast.These changes result in a significant enhancement in humidification efficiency,achieving a remarkable efficiency level of 78%.However,a wettability value of 630 m^(2)/m^(3)leads to a smaller reduction of these parameters.Increasing the pad thickness,particularly to 0.3 m,improves performance by boostingΔT,ΔRH,and effectiveness,especially for pads with a wettability of 630 m^(2)/m^(3),for which superior performances are predicted by the numerical tests.
基金supported by the Basic Science Center for Tibetan Plateau Earth System(No.41988101)the Science and Technology Plan Project of the Xizang Autonomous Region(No.XZ202201ZD0005G01)。
文摘The Tibetan Plateau(TP),known as the“Third Pole of Earth”,and its ecosystem is quite sensitive to climate change(Yao et al.,2012;Qiu,2008).In recent decades,the main TP has experienced warming and humidification(although there has been a drying trend in the southern region),and researchers anticipate that this change will continue in the future(Jiang et al.,2023;Sun et al.,2020;Chen et al.,2015).
基金financially supported by the UK Research Council EPRSC EP/W03395X/1the Program grant SynHiSel EP/V047078/1the Hydrogen and Fuel Cells Hub(H_(2)FC SUPERGEN)EP/P024807/1。
文摘Hydrophilicity is critical in Nafion membranes during fuel cell operation as insufficient membrane hydration leads to brittle behavior and a drop in proton conductivity.The incorporation of APTS(3-(aminopro pyl)triethoxysilane)into exfoliated graphene oxide(EGO)by covalent functionalization to be used as filler into Nafion membranes allows higher hydrophilicity for these membranes.This is associated with promoting hydroxyl,carbonyl,siloxane,silane,and amine groups within the EGO-APTS matrix.The incorporation of these materials as Fuel Cell MEAs leads to a significant reduction of the ohmic resistance measured at high frequency resistance(HFR)in electrochemical impedance spectroscopy(EIS)experiments and achieves maximum power densities of 1.33 W cm^(-2)at 60℃ at 100%RH(APTS-EGO,0.2 wt%)and1.33 W cm^(-2)at 60℃ at 70%RH(APTS-EGO,0.3 wt%),which represents an improvement of 190%compared to the commercial Nafion 212 when utilizing low humidification conditions(70%).Moreover,the as-synthesized membrane utilizes lower Nafion ionomer mass,which,in conjunction with the excellent cell performance,has the potential to decrease the cost of the membrane from 87 to 80￡/W as well as a reduction of fluorinated compounds within the membrane.
基金supported by the National Natural Science Foundation of China(9112502531400319)
文摘Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and utilize saturated atmospheric water such as fog, dew and condensed water. So far, however, there have been few studies on the aerial parts of desert plants in their absorption of unsaturated water from the atmosphere. This study presents an ultrasonic humidification fluorescent tracing method of detecting unsaturated atmospheric water absorption by the aerial parts of desert plants. We constructed an organic glass room based on the sizes of field plants. Then, the aboveground parts of the plants were humidified in the sealed glasshouse using an ultrasonic humidifier containing fluorescent reagents. The humidity and wetting time were controlled by turning on or off the humidifier according to the reading of a thermo-hygrometer suspended in the glasshouse. Fluorescence microscopy was employed to observe these plant samples. This method can generate unsaturated atmospheric water vapor and incorporate other fluorescent reagents or water-soluble chemical reagents for gasified humidification. In addition, it can identify plant parts that absorb unsaturated atmospheric water from the air, detect water absorption sites on the surface of leaves or tender stems, and determine the ability of tissues or microstructure of aerial parts to absorb water. This method provides a direct visual evidence for the inspection of leaf or tender stem microstructure in response to unsaturated atmospheric water absorption. Moreover, this method shows that aqueous pores in the cuticles of leaves or tender stems of desert plants are large enough to allow the passage of ionic fluorescent brightener with a molecular weight of up to 917 g/mol. Thus, this paper provides an important approach that explores the mechanism by which desert plants utilize unsaturated atmospheric water.
基金Supported by the National Natural Science Foundation of China China Energy Conservation Investment Corporation as a key project (No. 20236030).
文摘A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several operating conditions on the productivity and thermal efficiency of the column were investigated. The results show that both the productivity and thermal efficiency of the column enhance with the elevation of the inlet water temperature. The flow rates of water and carrier gas both have optimal operating ranges, which are 10-30 kg·h^-1 and 4-7kg·h^-1 for the present column, respectively. Meanwhile, the increase of external steam flow rate will promote the productivity of the column but reduce its thermal efficiency.
基金Supported by the Natural Science Foundation of Jiangsu Province (BK97124) the National Natural Science Foundation (No. 20376032)+1 种基金 the Outstanding Youth Fund of National Natural Science Foundation (No. 29925616)Key Fund of National Natural Science Fo
文摘Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water temperature and large water flow are needed. The water temperature is the most sensitive parameter to the humidification tower. And it is better for the humidification tower to work at temperature higher than 523 K when the system pressure is higher than 5 MPa. The comparison between the model used in this paper and ideal model shows that the ideal model can be used in simulation to simply the calculation when the temperature is lower than 473 K and pressure is lower than 5 MPa.
文摘Solar humidification-dehumidification desalination technology has been reviewed in detail in this paper. This review would also throw light on the scope for further research and recommendations in active distillation system by humidification and dehumidification (HDH). Also in this article, a review has been done on different types of (HDH) systems. Thermal modeling was done for various types of humidification and dehumidification(HDH) distillation system. From the present review, it is found that the humidification-dehumidification desalination process HDH will be a suitable choice for fresh water production when the demand is decentralized. HDH is a low temperature process where total required thermal energy can be obtained from solar energy. Capacity of HDH units is between that produced by conventional methods and solar stills. Moreover, HDH is distinguished by simple operation and maintenance. Also from the present condensed review, it was observed that an increase in evaporator and condenser surface areas significantly improves system productivity. But prior to implementing any techniques in design improvement, it is necessary to optimize the MEH unit by optimizing its component size to understand the effect of feed water and air flow rates. Although a fair amount of simulation studies have been conducted in the past, further design simulation is required to fully understand the complicated effects of air and water flow rates, the optimum size of individual components or modules of the unit and to generate a comprehensive model for the system.
基金Foundation item： Project（51178392） supported by the National Natural Science Foundation of China
文摘A parameter, known as the parameter of humidification vibration deformation, was proposed, describing quantitatively the impact of water content on vibration settlement deformation, and its relationship with humidification water content, dynamic shear stress peak value, initial consolidation stress and vibration frequency was built. The result shows that 1） the parameter of humidification vibration deformation increases with the vibration shear stress peak value increasing. 2） The humidification water content has significant influence on the curve of the parameter of humidification vibration deformation and the peak vibration shear stress. When the humidification water content is low, the curve increases slowly. However, when the humidification water content is high, the curve increases rapidly. 3） Initial consolidation stress has significant influence on the humidification vibration deformation coefficient. When initial consolidation stress is not large enough to destroy the loess structure, with initial consolidation stress increasing, the humidification vibration deformation coefficient decreases. On the contrary, the humidification vibration deformation coefficient increases with initial consolidation stress increasing. 4） With the increase of vibration time, the parameter of humidification vibration settlement shows an increasing trend overall. The initial dynamic shear stress peak value and humidification water content all have significant effects on the curve of the parameter of humidification vibration settlement and vibration time. However, the humidification water content is even more significant.
文摘[Objective] This study aimed to analyze the evolution characteristics and occurrence patterns of droughts and floods in Weifang City. [Method] Based on the monthly precipitation data during 1961-2010 obtained from nine meteorological sta- tions of Weifang City, by using standardized precipitation index, monthly SPI index of Weifang City during the past 50 years was calculated to analyze the spatial and temporal distribution characteristics of drought and humidification in Weifang City. [Result] The results showed that the variation of drought and humidification had stage characteristics in Weifang City, which was relatively humid in the 1960s and 1970s and developed from extremely humid in early 1960s to dry in late 1970s, persistent drought was observed throughout the range of Weifang City in the 1980s, and the variation tended to be smooth during the 1990s-2000s. Spatial distribution of drought and humidification in Weifang City showed certain regional characteristics. In the 1960s, the mid-west region of Weifang City was relatively humid, while the southeastern region was relatively dry; in the 1970s, there was little difference among the drought and humidification extent in each region; in the 1980s, each region of Weifang City was generally dry, specifically, drought in the southeastern region was the most severe, while drought in the northern region was the slightest; in the 1990s and 2000s, variation of drought and humidification in each region of Weifang City was basically the same. The uneven spatial and temporal distribution of precipi- tation led to abnormal distribution of drought and humidification in some areas, such as the abnormal phenomenon in 1999; the spatial distribution of drought and humidi- fication duration in each generation had their own characteristics, which brought diffi- culties to the unified deployment of drought and flood control departments. [Conclu- sion] This study provided theoretical basis for the drought resistance, waterlogging prevention and disaster reduction in Weifang City under the background of climate change.
文摘Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution characteristics, and analyzes the mass concentration and the particulate number concentration distribution of different sizes of particulates with time under each condition of the purified water humidification, the tap water humidification and the cold boiled water humidification in the office. The results show that under the three kinds of wetting conditions, the concentration of the fine particulates is higher. More minerals are contained in the tap water and the cold boiled water, so the two kinds of humidification have more significant impact on indoor particulate matter. But the purified water humidification has nearly no significant effect on it. The calcium and magnesium ionic compounds are partly removed after the water boiled, so the cold boiled water humidification has less impact on the indoor particulate matter than the tap water humidification. The mass concentration and particulate number concentration of the particle may also be affected due to the frequency of ultrasonic vibration.
基金Supported by National Natural Science Foundation of ChinaChina Energy Conservation Investment Corporation as a key project(No.20236030) .
文摘The polypropylene tubes with surface modification were installed in a baffled shell-tube column to conduct the thermally coupled humidification and dehumidification desalination process. The effects of several operating parameters （feed water temperature, water flow rate, carrier air flow rate, and external steam flow rate） on the productivity and thermal efficiency of this column were investigated experimentally. The results show that the feed water temperature has a positive effect on the productivity and thermal efficiency, while the flow rates of external steam, feed water, and carrier air should be optimized within the ranges of 0.006-0.020 kg·m^-2·s^-1 , 0.005-0.015 kg·m^-2·s^-1, and 0.7-1.3kg·m^-2·s^-1, respectively; the flow rates of feed water and carrier air are greatly controlled by the wetting state of the tubes. In comparison with the previous desalination column installing the coppery tubes, the present column can reach nearly the same production capacity of distilled water, which demonstrates the feasibility of applying such a plastic column to the humidification and dehumidification desalination process.
基金Funding for this project was provided by the CSIRO National Research Collec-tions Australia Strategic Funding and the Australian National Wildlife Collec-tion Curatorial Internship Program.
文摘Background:Bird nests are an important part of avian ecology.They are a powerful tool for studying not only the birds that built them,but a wide array of topics ranging from parasitology,urbanisation and climate change to evolu-tion.Despite this,bird nests tend to be underrepresented in natural history collections,a problem that should be redressed through renewed focus by collecting institutions.Methods:Here we outline the history and current best practice collection and curatorial methods for the nest col-lection of the Australian National Wildlife Collection(ANWC).We also describe an experiment conducted on nests in the ANWC using ultrasonic humidification to restore the shape of nests damaged by inappropriate storage.Results:The experiment showed that damaged nests can be successfully reshaped to close to their original dimen-sions.Indeed,restored nests were significantly closer to their original shape than they were prior to restoration.Thus,even nests damaged by years of neglect may be fully incorporated into active research collections.Best practice techniques include extensive note taking and photography in the field,subsampling of nests that cannot or should not be collected,appropriate field storage,metadata management,and prompt treatment upon arrival at the collec-tion facility.Conclusions:Renewed focus on nest collections should include appropriate care and restoration of current col-lections,as well as expansion to redress past underrepresentation.This could include collaboration with researchers studying or monitoring avian nesting ecology,and nest collection after use in bird species that rebuild anew each nesting attempt.Modern expansion of museum nest collections will allow researchers and natural history collections to fully realise the scientific potential of these complex and beautiful specimens.
文摘This paper introduced a novel self-adjustment of parameters of fuzzy neural networks. Then, the effects of cathode humidification temperature and anode flow rate on the performance of direct methanol fuel celI（DMFC） were described respectively. Two dynamic performance models of DMFC under the influences of cathode humidification temperature and anode flow rate were established separately based on fuzzy neural networks. The simulation results show the accuracy of the models established is satisfactory.
文摘Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and maxillofacial surgery with tracheal intubation, continuous infusion can be adjusted to the wet method;according to the wet pipe, insertion depth of the flow rate is divided into four groups, by four different depths and velocities of the wetting effect, to be analyzed. Results: B group was significantly lower than other groups satisfied with indicators of four significantly different effects of humidification. Conclusion: When continuous humidification tube insertion depth of endotracheal intubation is 10 - 12 cm, and flow rate is 15 - 20 ml/h, the wetting effect will achieve greater satisfaction.
文摘In making the gas-solid-liquid phase analysis, based on the collaborative study of the internal and external humidification ratio of desulfurization efficiency, determine the humidifier ratio within 60% to 75%, that can make the best balance between the respective merits of a simple tower humidifiers tower humidifier way, optimizing the overall desulfurization reaction, effectively reducing the sticky wall, stick in the desulfurization efficiency and reduce the wall to achieve a balance between the balance, without increasing the sorbent and process water, under the premise can promote the desulfurization reaction, improve the desulfurization sorbent utilization and efficiency, help desulfurization reaction system is stable, efficient and economic operation, the gas-liquid-solid three-phase to achieve better synergy.
文摘Most of the desalination technologies consume a huge quantity of energy resulting from petroleum products in the form of heat or electrical energy. Solar desalination is a promisingly sustainable freshwater production technology. Solar desalination humidification dehumidification process showed the best approach as it is of the highest overall energy efficiency. In this review paper, a detailed study of the previous work is performed on solar humidification dehumidification desalination techniques experimentally and theoretically. Also in this review, different types of HDH systems were mentioned. The review showed that the humidification dehumidification desalination systems are suitable for decentralized demand. On the other hand, capacity of HDH units is not as large as conventional methods or small as solar stills. Finally, this study threw light on the scope of the parameters which have a considerable influence on increasing the freshwater output of the HDH systems as feed water flow rate, air flow rate, and design of the evaporator, condenser, and packing material. A brief economical study and a comparison of the costs per liter are performed for various humidification dehumidification desalination systems presented in this study.
基金National Natural Science Foundation of China,No.42171095,No.42371123General Project of Key Research and Development Program of Shaanxi Province,No.2024SF-YBXM-532+2 种基金The Social Science Foundation of Shaanxi Province,No.2020D039Fundamental Research Funds for the Central Universities,No.GK202201008Open Foundation of the State Key Laboratory of Urban and Regional Ecology of China,No.SKLURE2022-2-1。
文摘Recent climate change has accelerated the global hydrological cycle, substantially affecting drought metrics such as drought duration and drought propagation;however, knowledge of drought patterns in these metrics remains limited. Here, we aimed to address the evolution and influencing factors of major drought metrics under past and future climate scenarios within the Yellow River Basin(YRB) based on Coupled Model Intercomparison Project Phase 6(CMIP6). Accordingly, we investigated the changes in drought duration for meteorological drought and agricultural drought across the YRB and identified the variability in drought propagation time from meteorological drought to agricultural drought by using a standardized precipitation/soil moisture index and run theory. Meteorological and agricultural drought duration, and propagation time, increased from 1850 to 2014, decreased significantly from 2015 to 2100 with change trends of –0.0027, –0.0197, and –0.002 month/year, respectively. Drought duration had a negative sensitivity to humidification, and agricultural drought was more sensitive than meteorological drought. Propagation time exhibited a greater sensitivity to meteorological humidification than agricultural humidification. The results also suggest that precipitation, evapotranspiration, and soil moisture are the main drivers of drought metric changes, with air temperature and crop cover exhibiting a strong indirect effect on drought metrics in the YRB. Decreased propagation time from meteorological to agricultural drought and decreased duration provide evidence for the accelerated occurrence and increased impact of drought, highlighting the importance of a more comprehensive understanding of drought metric changes under rapid climate change.
基金supported by the China?s Second Scientific Research Project on the Qinghai±Xizang Plateau(grant 2019QZKK0405-02)the National Natural Science Foundation of China Project(grant 42471056)the Fundamental Research Funds for the Central Universities
文摘The drylands on the Qinghai–Xizang Plateau are extremely sensitive to climate change and grazing activities.However,there is a lack of quantitative study of the combined effects of aridity and grazing pressure,which are vital in determining the sustainable grazing areas.In this study,a 2-dimensional threshold model was employed to assess the maximum allowable grazing pressure and determine the sustainable grazing areas under both historical conditions and projected climate change scenarios up to 2100.Results showed that 62.2%of the drylands under historical condition were unsuitable for grazing and 6.7%exceeded the ecological threshold,while 31.1%fell within the areas with sustainable grazing.Model projections indicate a trend toward humidification across the drylands under the climate change scenarios of RCP 4.5 and RCP 8.5.This process is expected to partially alleviate the negative impact of grazing,leading to an expansion of sustainable grazing areas to approximately 41.0%by 2100.These findings provide valuable insights for optimizing grazing strategies in the drylands of the Qinghai–Xizang Plateau in the future.
