The model of a three-terminal thermoelectric refrigerator with ideal tunneling quantum dots is established. It consists of a cavity connected to two quantum dots embedded between two electron reservoirs at different t...The model of a three-terminal thermoelectric refrigerator with ideal tunneling quantum dots is established. It consists of a cavity connected to two quantum dots embedded between two electron reservoirs at different temperatures and chemical potentials. According to the Landauer formula the expressions for the heat current, the cooling rate and the coefficient of performance （COP） are derived analytically. The performance characteristic curves of the cooling rate versus the coefficient of performance are plotted with numerical calculation. The optimal regions of the cooling rate and the COP are determined. Moreover, we optimize the cooling rate and the COP with respect to the position of energy level of the right quantum dot, respectively. The influence of the width of energy level and the temperature ratio on performance of the three-terminal thermoelectric refrigerator is analyzed. Lastly, when the width of energy level is small enough, the optimal performance of the refrigerator is discussed in detail.展开更多
To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality c...To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality comparative analysis(MAIRCA)approaches are proposed.According to the features of LTE-M system,the risk evaluation system is established.The enhanced structural entropy weight method is used to obtain the weight.Furthermore,it is combined with nine-element fuzzy mathematics to transform the degree of membership,modifying the conflict and fusion rules to solve the confidence degree clashed problem of evidence theory.Then,the system risk grade assessment result is obtained.For the purpose of forming the ranking of indicator importance,the MAIRCA is introduced and the ranking is three-dimensional.The operational state of the metro line is used as the data source in various ways the obtained risk grade increased by 7.12%.It is verified that MAIRCA can be applied to the field of urban rail transit because it has based on the test and calculation.The results show that the method is effective;compared with others,the confidence degree of excellent stability and the ranking result of risk factors is reasonable.The influencing indicator with the highest importance is the'equipment failure rate".展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11365015
文摘The model of a three-terminal thermoelectric refrigerator with ideal tunneling quantum dots is established. It consists of a cavity connected to two quantum dots embedded between two electron reservoirs at different temperatures and chemical potentials. According to the Landauer formula the expressions for the heat current, the cooling rate and the coefficient of performance （COP） are derived analytically. The performance characteristic curves of the cooling rate versus the coefficient of performance are plotted with numerical calculation. The optimal regions of the cooling rate and the COP are determined. Moreover, we optimize the cooling rate and the COP with respect to the position of energy level of the right quantum dot, respectively. The influence of the width of energy level and the temperature ratio on performance of the three-terminal thermoelectric refrigerator is analyzed. Lastly, when the width of energy level is small enough, the optimal performance of the refrigerator is discussed in detail.
基金supported by grants from the National Natural Science Foundation of China(Grant No.61661027)the Gansu Provincial Department of Education:Excellent Postgraduate‘Innovation Star’Project(Grant No.2022CXZX-619).
文摘To assess the operational safety risk of long-term evolution for the metro(LTE-M)communication system more accurately,the guide maintenance strategy,the improved evidence theory and the multi-attribute ideal reality comparative analysis(MAIRCA)approaches are proposed.According to the features of LTE-M system,the risk evaluation system is established.The enhanced structural entropy weight method is used to obtain the weight.Furthermore,it is combined with nine-element fuzzy mathematics to transform the degree of membership,modifying the conflict and fusion rules to solve the confidence degree clashed problem of evidence theory.Then,the system risk grade assessment result is obtained.For the purpose of forming the ranking of indicator importance,the MAIRCA is introduced and the ranking is three-dimensional.The operational state of the metro line is used as the data source in various ways the obtained risk grade increased by 7.12%.It is verified that MAIRCA can be applied to the field of urban rail transit because it has based on the test and calculation.The results show that the method is effective;compared with others,the confidence degree of excellent stability and the ranking result of risk factors is reasonable.The influencing indicator with the highest importance is the'equipment failure rate".
