When plants absorb more light than that can be used for photosynthesis, the excessive energy can cause photoinhibition and even photooxidation of photosynthetic apparatus. Xanthophyll cycle-dependent photo-protection ...When plants absorb more light than that can be used for photosynthesis, the excessive energy can cause photoinhibition and even photooxidation of photosynthetic apparatus. Xanthophyll cycle-dependent photo-protection is believed to be the main mechanism for plants to deal with excessive light energy. This review focuses on molecular biological aspects and regulations of violaxanthin de-epoxidase and zeaxanthin epoxidase involved in xanthophyll cycle. We will summarize the functions of xanthophyll cycle, especially recent advances in its thermal dissipation mechanism of photoprotection. Some interesting issues deserving further study will be discussed.展开更多
Heat strain experienced by individuals wearing chemical protective clothing(CPC)is severe and dangerous especially in hot-humid environment.The development of material science and interdisciplinary studies including e...Heat strain experienced by individuals wearing chemical protective clothing(CPC)is severe and dangerous especially in hot-humid environment.The development of material science and interdisciplinary studies including ergonomics,physiology and heat transfer is urgently required for the reduction of heat strain.The aim of this paper was to study the relationship among clothing thermal properties,physiological responses and environmental conditions.Three kinds of CPC were selected.Eight participants wore CPC and walked(4 km/h,two slopes with 5%and 10%)on a treadmill in an environment with(35±0.5)℃ and RH of(60±5)%.Core temperature,mean skin temperature,heart rate,heat storage and tolerance time were recorded and analyzed.Physiological responses were significantly affected by the clothing thermal properties and activity intensity in hot-humid environment.The obtained results can help further development of heat strain model.New materials with lower evaporative resistance and less weight are necessary to release the heat strain in hot-humid environments.展开更多
Mine refuge chambers are used to shield miners who fail to escape from the mine when incidents occur. Environment maintaining system plays a key role in stabilizing thermal environment of a mine refuge chamber against...Mine refuge chambers are used to shield miners who fail to escape from the mine when incidents occur. Environment maintaining system plays a key role in stabilizing thermal environment of a mine refuge chamber against heat emitted from metabolism and transferred from outside. The safety and comfort of refugees are closely related to the environment maintaining system design. In order to improve the comfort of refugees, optimization on the environment maintaining system has been done based on the previous work. To evaluate the environment of the chamber, eight volunteers were involved into the experiment. Under close observation and safety protection, they lived in a heat-isolated test chamber for 106 hours. The volunteers were asked to maintain low level of activities to simulate refugees＇ situation. It shows that the environment maintaining system worked well and the temperature, relative humidity and emitted harmful air content such as CO2 and CO were all kept in the safety level, and no discomfort was felt by volunteers at all.展开更多
Heat moving source models along with transient heat analysis by finite element method were used to determine weld thermal cycles and isothermal sections obtained from the application of a gas tungsten arc welding bead...Heat moving source models along with transient heat analysis by finite element method were used to determine weld thermal cycles and isothermal sections obtained from the application of a gas tungsten arc welding beads on Inconel 718 plates. Analytical (Rosenthal’s thick plate model) and finite element results show an acceptable approximation with the experimental weld thermal cycles. The isothermal sections determined by numerical simulation show a better approximation with the experimental welding profile for double-ellipse model heat distribution than Gauss model. To analyze the microstructural transformation produced by different cooling rates in the fusion and heat affected zones, Vickers microhardness measurements (profile and mapping representation) were conducted. A hardness decrement for the heat affected zone (~200 HV0.2) and fusion zone (~240 HV0.2) in comparison with base material (~350 HV0.2) was observed. This behavior has been attributed to the heterogeneous solubilization process of the γ″ phase (nickel matrix), which, according to the continuous-cooling-transformation curve, produced the Laves phase,δ and MC transition phases, generating a loss in hardness close to the fusion zone.展开更多
Building cooling, heating and power (BCHP) systems should play an important role in achieving the goals of energy efficient use and environment protection in China. It will make big sense when this type of system show...Building cooling, heating and power (BCHP) systems should play an important role in achieving the goals of energy efficient use and environment protection in China. It will make big sense when this type of system shows a good performance energetically and economically. An on-site BCHP system being the first in the country was installed and put to use five years ago. As the first step to evaluate the project, computations were made based on thermodynamic and thermoeconomic theories to evaluate the system on full load and off-design conditions in summer. Discussion and analyses are made mainly in terms of exergetic efficiency and costs of unit amount of useful exergy produced in this paper.展开更多
The aim of this paper is to present the preliminary experimental analysis results carried out on the commercial internal combustion engine set in a CHP （combined heat and power） mode, fueled by renewable hydrogen an...The aim of this paper is to present the preliminary experimental analysis results carried out on the commercial internal combustion engine set in a CHP （combined heat and power） mode, fueled by renewable hydrogen and methane mixtures. The hydrogen is produced by an alkaline electrolyser fed by a 5.8 kWp grid connected PV （photovoltaic） plant. The acceptance test conducted with hydrogen percentages ranging from 0%-10% has been carried out at partial load： 45 kW^l instead of the full power of 60 kWe~. In order to evaluate the CHP energy consumption and environmental performance （NOx and CO）, the analysis was conducted for 240 h, using a portable flue gas analyser and two mass flow meters for hydrogen and methane. Without engine parameters optimization--relative equivalence ratio （2） and spark advance--increasing hydrogen addition rate, a slight enhancement in electrical efficiency occurs. Furthermore, due to the engine control system and lower blends LHV （lower heating value）, the methane consumption decreases disproportionately to the hydrogen amount in the mixture. Finally, referring to standard operating condition, the environmental results show that using enrichment of 10%, running the engine with 18 degrees spark advance and 2 of 1.4, CO and NOx emissions are reduced by 6.3% and 27% respectively.展开更多
Developing countries as Mexico lack their own emission factors for thermoelectric power plants, so they have the need to develop them, considering specific operation conditions for each plant. This study develops spec...Developing countries as Mexico lack their own emission factors for thermoelectric power plants, so they have the need to develop them, considering specific operation conditions for each plant. This study develops specific emission factors in Mexico for： sulfur dioxide （SO2）, nitrogen oxides （NOx） and particles, for thermoelectric power plants that use fuel oil. This work was necessary due to the differences found between the measured and the calculated emissions, using emission factors of different agencies, such as, US-EPA （Environmental Protection Agency of the United States）, IPCC （Intergovernmental Panel on Climate Change）, and UK-NAEI （National Atmospheric Emissions Inventory of the United Kingdom）. The new emission factors were used to calculate the emissions of a thermoelectric power plant in Mexico. The comparisons between the measured and the calculated emissions （with the new emission factors） for 502, particles and NO2 were not significantly different （p 〉 0.05）.展开更多
文摘When plants absorb more light than that can be used for photosynthesis, the excessive energy can cause photoinhibition and even photooxidation of photosynthetic apparatus. Xanthophyll cycle-dependent photo-protection is believed to be the main mechanism for plants to deal with excessive light energy. This review focuses on molecular biological aspects and regulations of violaxanthin de-epoxidase and zeaxanthin epoxidase involved in xanthophyll cycle. We will summarize the functions of xanthophyll cycle, especially recent advances in its thermal dissipation mechanism of photoprotection. Some interesting issues deserving further study will be discussed.
文摘Heat strain experienced by individuals wearing chemical protective clothing(CPC)is severe and dangerous especially in hot-humid environment.The development of material science and interdisciplinary studies including ergonomics,physiology and heat transfer is urgently required for the reduction of heat strain.The aim of this paper was to study the relationship among clothing thermal properties,physiological responses and environmental conditions.Three kinds of CPC were selected.Eight participants wore CPC and walked(4 km/h,two slopes with 5%and 10%)on a treadmill in an environment with(35±0.5)℃ and RH of(60±5)%.Core temperature,mean skin temperature,heart rate,heat storage and tolerance time were recorded and analyzed.Physiological responses were significantly affected by the clothing thermal properties and activity intensity in hot-humid environment.The obtained results can help further development of heat strain model.New materials with lower evaporative resistance and less weight are necessary to release the heat strain in hot-humid environments.
文摘Mine refuge chambers are used to shield miners who fail to escape from the mine when incidents occur. Environment maintaining system plays a key role in stabilizing thermal environment of a mine refuge chamber against heat emitted from metabolism and transferred from outside. The safety and comfort of refugees are closely related to the environment maintaining system design. In order to improve the comfort of refugees, optimization on the environment maintaining system has been done based on the previous work. To evaluate the environment of the chamber, eight volunteers were involved into the experiment. Under close observation and safety protection, they lived in a heat-isolated test chamber for 106 hours. The volunteers were asked to maintain low level of activities to simulate refugees＇ situation. It shows that the environment maintaining system worked well and the temperature, relative humidity and emitted harmful air content such as CO2 and CO were all kept in the safety level, and no discomfort was felt by volunteers at all.
基金CONACyT-México for the scholarship providedCONACyT (Project 736)SIP-IPN are also acknowledged for funds given to conduct this research
文摘Heat moving source models along with transient heat analysis by finite element method were used to determine weld thermal cycles and isothermal sections obtained from the application of a gas tungsten arc welding beads on Inconel 718 plates. Analytical (Rosenthal’s thick plate model) and finite element results show an acceptable approximation with the experimental weld thermal cycles. The isothermal sections determined by numerical simulation show a better approximation with the experimental welding profile for double-ellipse model heat distribution than Gauss model. To analyze the microstructural transformation produced by different cooling rates in the fusion and heat affected zones, Vickers microhardness measurements (profile and mapping representation) were conducted. A hardness decrement for the heat affected zone (~200 HV0.2) and fusion zone (~240 HV0.2) in comparison with base material (~350 HV0.2) was observed. This behavior has been attributed to the heterogeneous solubilization process of the γ″ phase (nickel matrix), which, according to the continuous-cooling-transformation curve, produced the Laves phase,δ and MC transition phases, generating a loss in hardness close to the fusion zone.
文摘Building cooling, heating and power (BCHP) systems should play an important role in achieving the goals of energy efficient use and environment protection in China. It will make big sense when this type of system shows a good performance energetically and economically. An on-site BCHP system being the first in the country was installed and put to use five years ago. As the first step to evaluate the project, computations were made based on thermodynamic and thermoeconomic theories to evaluate the system on full load and off-design conditions in summer. Discussion and analyses are made mainly in terms of exergetic efficiency and costs of unit amount of useful exergy produced in this paper.
文摘The aim of this paper is to present the preliminary experimental analysis results carried out on the commercial internal combustion engine set in a CHP （combined heat and power） mode, fueled by renewable hydrogen and methane mixtures. The hydrogen is produced by an alkaline electrolyser fed by a 5.8 kWp grid connected PV （photovoltaic） plant. The acceptance test conducted with hydrogen percentages ranging from 0%-10% has been carried out at partial load： 45 kW^l instead of the full power of 60 kWe~. In order to evaluate the CHP energy consumption and environmental performance （NOx and CO）, the analysis was conducted for 240 h, using a portable flue gas analyser and two mass flow meters for hydrogen and methane. Without engine parameters optimization--relative equivalence ratio （2） and spark advance--increasing hydrogen addition rate, a slight enhancement in electrical efficiency occurs. Furthermore, due to the engine control system and lower blends LHV （lower heating value）, the methane consumption decreases disproportionately to the hydrogen amount in the mixture. Finally, referring to standard operating condition, the environmental results show that using enrichment of 10%, running the engine with 18 degrees spark advance and 2 of 1.4, CO and NOx emissions are reduced by 6.3% and 27% respectively.
文摘Developing countries as Mexico lack their own emission factors for thermoelectric power plants, so they have the need to develop them, considering specific operation conditions for each plant. This study develops specific emission factors in Mexico for： sulfur dioxide （SO2）, nitrogen oxides （NOx） and particles, for thermoelectric power plants that use fuel oil. This work was necessary due to the differences found between the measured and the calculated emissions, using emission factors of different agencies, such as, US-EPA （Environmental Protection Agency of the United States）, IPCC （Intergovernmental Panel on Climate Change）, and UK-NAEI （National Atmospheric Emissions Inventory of the United Kingdom）. The new emission factors were used to calculate the emissions of a thermoelectric power plant in Mexico. The comparisons between the measured and the calculated emissions （with the new emission factors） for 502, particles and NO2 were not significantly different （p 〉 0.05）.
