We investigate the free energy relation for a system contacting with a non-Markovian heat bath and find that the validity of the relation sensitively depends on the non-Markovian memory effect, which is especially rel...We investigate the free energy relation for a system contacting with a non-Markovian heat bath and find that the validity of the relation sensitively depends on the non-Markovian memory effect, which is especially related go the initial preparation effect. This memory effect drives the statistical distribution of the system out of the initial preparation, even if the system starts from an equilibrium state. This leads to the violation of the free energy relation. A possible way of eliminating this memory effect is proposed.展开更多
Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess th...Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h,respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time.Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.展开更多
This paper reports the effects of two trainings-5 km cross-country race and 15 min heat-bath on theimprovement of heat-tolerance. All subjects of the training group were asked to perform a training once daily for 10to...This paper reports the effects of two trainings-5 km cross-country race and 15 min heat-bath on theimprovement of heat-tolerance. All subjects of the training group were asked to perform a training once daily for 10to 12 d within two weeks. The results proved that the cross-country race training both in the artificial hot chamberand on the drill ground of troop could obtain evident training-adaptation. The rectal temperature, heart rate, andsweat volume reduced by 0. 39℃, 13. 2 b/min and 338 g during training in field, respectively. In the same period ofcross-country race training, the normal military exercises, labours and natural heat acclimatization in the summercould only raise slightly the level of heat acclimatization in soldiers. Heat-bath training could reduce rectal temperature by 0. 6℃ during immersion in hot water, however, the level of heat-tolerance in a hot climatic chamber was inferior to that attained by cross-country race, march and running training.展开更多
Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). B...Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m^3·h^-1. Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.展开更多
We examined wood liquefaction using phenol and mixed acid catalysts with microwave heating, and compared that with similar processes that use oil bath heating. The reaction time for microwave heating to achieve a resi...We examined wood liquefaction using phenol and mixed acid catalysts with microwave heating, and compared that with similar processes that use oil bath heating. The reaction time for microwave heating to achieve a residue content was one sixth, one eighteenth, and one twenty-fourth of that from oil bath heating, respectively, for phenol to wood （P/W） ratios of 2.5/1, 2/1 and 1.5/1. A low P/W ratio tended to result in carbonization of liquefied wood due to an insufficient amount of phenol and localized microwave superheating. Fourier transform infrared spectroscopic （FTIR） evaluation of the liquefied residue, showed that the liquefaction rates of wood com- ponents differed. Hemicellulose was most susceptible to liquefaction, crystalline cellulose was most recalcitrant, and guaiacyl units the most prone to re-condensation. From FTIR, the chemical components and substitution patterns of bonded phenol were similar for both methods.展开更多
In this study,we compared the effect of n-pentane and ice-water bath on removing the thermal effect in the poly（p-phenylene terephthalamide）（PPTA） polymerization process.The results indicate that the n-pentane can...In this study,we compared the effect of n-pentane and ice-water bath on removing the thermal effect in the poly（p-phenylene terephthalamide）（PPTA） polymerization process.The results indicate that the n-pentane can help to transfer the reaction heat faster and better.Adding suitable amount of n-pentanes into the PPTA preparation process not only improve the heat transfer,but also reduce the motor power in the polymerization process.Moreover,the introduction of n-pentane properly does not result in decrease of the inherent viscosity（η_（inh）） of polymer.Instead,it leads to increased viscosity of polymer during the PPTA preparation process.The results indicate that n-pentane can effectively transfer the reaction heat and avoid overheating during the polymerization of PPTA.展开更多
A mathematical model describing the flow field, heat transfer and the electromagnetic phenomenon in a DC electric arc furnace has been developed. First the governing equations in the arc plasma region are solved and t...A mathematical model describing the flow field, heat transfer and the electromagnetic phenomenon in a DC electric arc furnace has been developed. First the governing equations in the arc plasma region are solved and the calculated results of heat transfer, current density and shear stresses on the anode surface are used as boundary conditions in a model of molten bath. Then a two-dimensional time-dependent model is used to describe the flow field and electromagnetic phenomenon in the molten bath. Moreover, the effect of bottom electrode diameter on the circulation of molten bath is studied.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10875011 and 11075016)the National Basic Research Program of China (Grant No. 2007CB814805)+1 种基金the Fundamental Research Funds for the Central Universities of China(Grant No. 201001)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100003110007)
文摘We investigate the free energy relation for a system contacting with a non-Markovian heat bath and find that the validity of the relation sensitively depends on the non-Markovian memory effect, which is especially related go the initial preparation effect. This memory effect drives the statistical distribution of the system out of the initial preparation, even if the system starts from an equilibrium state. This leads to the violation of the free energy relation. A possible way of eliminating this memory effect is proposed.
基金financially supported by the Special Scientific Research Fund for Public Service Sectors of Forestry(Grant No.201504603)Science and Technology Projects of Fujian Province(2014NZ003)the National Natural Science Foundation of China(Grant Nos.31370560,31170520)
文摘Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h,respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time.Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.
文摘This paper reports the effects of two trainings-5 km cross-country race and 15 min heat-bath on theimprovement of heat-tolerance. All subjects of the training group were asked to perform a training once daily for 10to 12 d within two weeks. The results proved that the cross-country race training both in the artificial hot chamberand on the drill ground of troop could obtain evident training-adaptation. The rectal temperature, heart rate, andsweat volume reduced by 0. 39℃, 13. 2 b/min and 338 g during training in field, respectively. In the same period ofcross-country race training, the normal military exercises, labours and natural heat acclimatization in the summercould only raise slightly the level of heat acclimatization in soldiers. Heat-bath training could reduce rectal temperature by 0. 6℃ during immersion in hot water, however, the level of heat-tolerance in a hot climatic chamber was inferior to that attained by cross-country race, march and running training.
基金Islamic Azad University(IAU)Shahrood Branch,Shahrood,IranGolestan Province Gas Company,Gorgan,Iran for their sponsorships.
文摘Natural gas is transported from producing regions to consumption regions by using transmission pipelines at high pressures. At consumption regions, the pressure of natural gas is reduced in city gate stations(CGSs). Before the pressure reduction process, the temperature of natural gas is increased usually by using a water bath heater,which burns natural gas as fuel, to protect against freezing of natural gas. These types of heat exchangers have a low efficiency and consume a lot of fuel to generate the required heat. In the current study, the twisted configuration of the heating coil is proposed and investigated to enhance the heat transfer through a water bath heater with a nominal capacity of 1000 m^3·h^-1. Firstly, the implementation procedure is validated with data collected from the CGS of Qaleh-Jiq(located in Golestan province of Iran). A very good agreement is achieved between the obtained results and the real data. Then, three different twist ratios are considered to examine the twisting effects. The proposed technique is evaluated in the terms of velocity, temperature, and pressure variations, and the results are compared with the conventional case, i.e. straight configuration. It is found that both the heat transfer rate and the pressure drop augment as the twist ratio is raised. Finally, it is concluded that the twisted tubes can reduce the length of the gas coil by about 12.5% for the model with low twist ratio, 18.75% for the model with medium twist ratio, and 25% for the model with high twist ratio as compared to the straight configuration.
基金financially supported by the ‘‘948Project’’ of State Forestry Administration(2012-4-28)
文摘We examined wood liquefaction using phenol and mixed acid catalysts with microwave heating, and compared that with similar processes that use oil bath heating. The reaction time for microwave heating to achieve a residue content was one sixth, one eighteenth, and one twenty-fourth of that from oil bath heating, respectively, for phenol to wood （P/W） ratios of 2.5/1, 2/1 and 1.5/1. A low P/W ratio tended to result in carbonization of liquefied wood due to an insufficient amount of phenol and localized microwave superheating. Fourier transform infrared spectroscopic （FTIR） evaluation of the liquefied residue, showed that the liquefaction rates of wood com- ponents differed. Hemicellulose was most susceptible to liquefaction, crystalline cellulose was most recalcitrant, and guaiacyl units the most prone to re-condensation. From FTIR, the chemical components and substitution patterns of bonded phenol were similar for both methods.
基金the National Program on Key Basic Research Project(973 Program)(No 2011 CB606101)National Natural Science Foundation of China(No51003052)National Science Foundation for Post-doctoral Scientists of China(No023205066) for financial support
文摘In this study,we compared the effect of n-pentane and ice-water bath on removing the thermal effect in the poly（p-phenylene terephthalamide）（PPTA） polymerization process.The results indicate that the n-pentane can help to transfer the reaction heat faster and better.Adding suitable amount of n-pentanes into the PPTA preparation process not only improve the heat transfer,but also reduce the motor power in the polymerization process.Moreover,the introduction of n-pentane properly does not result in decrease of the inherent viscosity（η_（inh）） of polymer.Instead,it leads to increased viscosity of polymer during the PPTA preparation process.The results indicate that n-pentane can effectively transfer the reaction heat and avoid overheating during the polymerization of PPTA.
文摘A mathematical model describing the flow field, heat transfer and the electromagnetic phenomenon in a DC electric arc furnace has been developed. First the governing equations in the arc plasma region are solved and the calculated results of heat transfer, current density and shear stresses on the anode surface are used as boundary conditions in a model of molten bath. Then a two-dimensional time-dependent model is used to describe the flow field and electromagnetic phenomenon in the molten bath. Moreover, the effect of bottom electrode diameter on the circulation of molten bath is studied.
