The energetics process of offehore typhoon in three kinds of explosive enhancement (TEE) are ana lyzed using ECMWF data. The results are as follows: (a) During the explosive development process，the enhancement of the...The energetics process of offehore typhoon in three kinds of explosive enhancement (TEE) are ana lyzed using ECMWF data. The results are as follows: (a) During the explosive development process，the enhancement of the rotational kinetic enersy (K) is mainly in the lower troposphere while that ofthe potential energy (PE) is in the upper troposphere. The magnitude of rotational kinetic energy islargely bigger than that of divergent enersy (KX). (b) The environmental energy advected into the typhoon was about 30% of the internal increment of typhoon energy. The magnitude of energy was an order larger than increment of typhoon energy. (c) Among those three kinds of explosively developed typhoon, the enersy transformation mechanisms are different. (d) The influence of environment fields onabrupt intensification of typhoons couldn’t be overestimated.展开更多
The air infiltration of buildings is closely related to its indoor and outdoor environment and energy consumption.However,measuring air infiltration of a building under natural conditions is time-consuming,easily affe...The air infiltration of buildings is closely related to its indoor and outdoor environment and energy consumption.However,measuring air infiltration of a building under natural conditions is time-consuming,easily affected and expensive,so it’s often inferred based on building airtightness in practical engineering.Empirical models can nevertheless make a rapid prediction without building parameters,which are widely applied in practical engineering.At present,most of the existing empirical models take residential buildings as objects,therefore they are difficult to be applied to public buildings.Hence,it is imperative to build an empirical model applicable to public buildings.In this study,the conversion coefficients between the airtightness(air change rate under the pressure difference of 50Pa)and the air infiltration rates under natural conditions of four typical zones of public buildings were analyzed.Firstly,the airtightness of four zones of public buildings in the cold region of China was measured.Secondly,their air infiltration rates under 1800 combined conditions of wind pressure and stack effect pressure were simulated based on the airtightness measured results.Finally,calculation and statistical analysis of the conversion coefficient were carried out based on the measured and simulated results,and the recommended value of conversion coefficient was proposed.Analysis results show that the CC of each zone is significantly affected by outdoor meteorological conditions and varies in a wide range(1#zone:3.21 to 188.44).It is advised to ignore the extreme data and take the mean value of the CC corresponding to 95%of the data volume as the recommended value(22.2).This study can provide theoretical basis for the formulation of standards for the performance evaluation of building airtightness.展开更多
With the aim to enhance the energy conversion efficiency of the rainbow shape piezoelectric transducer, an analysis model of energy conversion efficiency is established based on the elastic mechanics theory and piezoe...With the aim to enhance the energy conversion efficiency of the rainbow shape piezoelectric transducer, an analysis model of energy conversion efficiency is established based on the elastic mechanics theory and piezoelectricity theory. It can be found that the energy conversion efficiency of the rainbow shape piezoelectric transducer mainly depends on its shape parameters and ma- terial properties from the analysis model. Simulation results show that there is an optimal length ratio to generate maximum en- ergy conversion efficiency and the optimal length ratios and energy conversion efficiencies of beryllium bronze substrate trans- ducer and steel substrate transducer are （0.65, 2.21%） and （0.65, 1.64%） respectively. The optimal thickness ratios and energy conversion efficieneies of beryllium bronze substrate transducer and steel substrate transducer are （1.16, 2.56%） and （1.49, 1.57%） respectively. With the increase of width ratio and initial curvature radius, both the energy conversion efficiencies de- crease. Moreover, beryllium bronze flexible substrate transducer is superior to the steel flexible substrate transducer.展开更多
The failure modes of rock and soil under compression are complex phenomena that have not been explained in a mechanical perspective. However, large amounts of studies indicate that the failure modes of rock and soil s...The failure modes of rock and soil under compression are complex phenomena that have not been explained in a mechanical perspective. However, large amounts of studies indicate that the failure modes of rock and soil samples can be categorized into eight types. In this work, the inner tensile stress and the dissipation and conversion of energy of rock and soil under compression are analyzed, then the effective conversion coefficient of energy is deduced, thus the tensile failure criterion of rock and soil under compression is established. Combined with the shear strength criterion of Mohr–Coulomb, a tensile joint shear strength criterion for rock and soil under compression is built. Therefore, a mechanical criterion model concerning the failure modes of rock and soil under compression is established and verified by tests. This model easily explains the test results in the existing literature and many natural phenomena, such as collapse.展开更多
文摘The energetics process of offehore typhoon in three kinds of explosive enhancement (TEE) are ana lyzed using ECMWF data. The results are as follows: (a) During the explosive development process，the enhancement of the rotational kinetic enersy (K) is mainly in the lower troposphere while that ofthe potential energy (PE) is in the upper troposphere. The magnitude of rotational kinetic energy islargely bigger than that of divergent enersy (KX). (b) The environmental energy advected into the typhoon was about 30% of the internal increment of typhoon energy. The magnitude of energy was an order larger than increment of typhoon energy. (c) Among those three kinds of explosively developed typhoon, the enersy transformation mechanisms are different. (d) The influence of environment fields onabrupt intensification of typhoons couldn’t be overestimated.
基金The authors are indebted to the Natural Science Foundation of Shan-dong Province Youth Project(Grant no.ZR2020QE224).
文摘The air infiltration of buildings is closely related to its indoor and outdoor environment and energy consumption.However,measuring air infiltration of a building under natural conditions is time-consuming,easily affected and expensive,so it’s often inferred based on building airtightness in practical engineering.Empirical models can nevertheless make a rapid prediction without building parameters,which are widely applied in practical engineering.At present,most of the existing empirical models take residential buildings as objects,therefore they are difficult to be applied to public buildings.Hence,it is imperative to build an empirical model applicable to public buildings.In this study,the conversion coefficients between the airtightness(air change rate under the pressure difference of 50Pa)and the air infiltration rates under natural conditions of four typical zones of public buildings were analyzed.Firstly,the airtightness of four zones of public buildings in the cold region of China was measured.Secondly,their air infiltration rates under 1800 combined conditions of wind pressure and stack effect pressure were simulated based on the airtightness measured results.Finally,calculation and statistical analysis of the conversion coefficient were carried out based on the measured and simulated results,and the recommended value of conversion coefficient was proposed.Analysis results show that the CC of each zone is significantly affected by outdoor meteorological conditions and varies in a wide range(1#zone:3.21 to 188.44).It is advised to ignore the extreme data and take the mean value of the CC corresponding to 95%of the data volume as the recommended value(22.2).This study can provide theoretical basis for the formulation of standards for the performance evaluation of building airtightness.
基金National Natural Science Foundation of China (10972 102)Research Fund for the Doctoral Program of Higher Education of China (200802870007)Technology Research and Development Program of Jiangsu Province (BE2009163)
文摘With the aim to enhance the energy conversion efficiency of the rainbow shape piezoelectric transducer, an analysis model of energy conversion efficiency is established based on the elastic mechanics theory and piezoelectricity theory. It can be found that the energy conversion efficiency of the rainbow shape piezoelectric transducer mainly depends on its shape parameters and ma- terial properties from the analysis model. Simulation results show that there is an optimal length ratio to generate maximum en- ergy conversion efficiency and the optimal length ratios and energy conversion efficiencies of beryllium bronze substrate trans- ducer and steel substrate transducer are （0.65, 2.21%） and （0.65, 1.64%） respectively. The optimal thickness ratios and energy conversion efficieneies of beryllium bronze substrate transducer and steel substrate transducer are （1.16, 2.56%） and （1.49, 1.57%） respectively. With the increase of width ratio and initial curvature radius, both the energy conversion efficiencies de- crease. Moreover, beryllium bronze flexible substrate transducer is superior to the steel flexible substrate transducer.
基金Projects(41572277,41402239)supported by the National Natural Science Foundation of ChinaProject(2015A030313118)supported by the Natural Science Foundation of Guangdong Province,China+1 种基金Project(20120171110031)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(201607010023)supported by the Science and Technology Program of Guangzhou,China
文摘The failure modes of rock and soil under compression are complex phenomena that have not been explained in a mechanical perspective. However, large amounts of studies indicate that the failure modes of rock and soil samples can be categorized into eight types. In this work, the inner tensile stress and the dissipation and conversion of energy of rock and soil under compression are analyzed, then the effective conversion coefficient of energy is deduced, thus the tensile failure criterion of rock and soil under compression is established. Combined with the shear strength criterion of Mohr–Coulomb, a tensile joint shear strength criterion for rock and soil under compression is built. Therefore, a mechanical criterion model concerning the failure modes of rock and soil under compression is established and verified by tests. This model easily explains the test results in the existing literature and many natural phenomena, such as collapse.
