Amorphous and nanostructural Fe-B alloys made by mechanical alloying of elemental Fe and amorphous B powders have been studied using X-ray diffraction, differential scanning calorimetry and Mossbauer spectroscopy. It ...Amorphous and nanostructural Fe-B alloys made by mechanical alloying of elemental Fe and amorphous B powders have been studied using X-ray diffraction, differential scanning calorimetry and Mossbauer spectroscopy. It has been shown that the milling conditions have a strong effect on the alloying. The single phase amorphous alloy, which is limited at nominal composition of Fe60B40, has been produced only by milling in Ar atmosphere and in other composition range the mixture of nanostructure Fe-like phase and Fe2B compound with a little amorphous phase are obtained. While by milling in air atmosphere the introduction of oxygen in air may suppress the formation of amorphous phase, thus the compounds Fe2B may be synthesized with no trace of amorphous phase. The crystallization temperatures of amorphous phase in the resultant products are higher than those of a single amorphous alloy Fe60B40, and hardly independent of the milling conditions and the composition. In addition, it is revealed that detectable B content in the final products is lower than the nominal composition of all the initial samples, which indicates that some B atoms may be located in the disordered interfacial regions of the nanostructural alloyed mixtures.展开更多
This paper provides analytical diagnosis of mechanical conditions of medical waste incinerators used for healthcare waste (HCW) treatment in Tanzania. The main features assessed were types of incinerators, features of...This paper provides analytical diagnosis of mechanical conditions of medical waste incinerators used for healthcare waste (HCW) treatment in Tanzania. The main features assessed were types of incinerators, features of incinerators and incinerator house. The assessment was conducted in three levels of health care facilities (HCFs), that is, Regional, district hospitals and health centers, existed in 26 regions of Tanzania. Questionnaires, interview and checklists were used as tools for data collection. It was observed that High-Tech incinerators are mainly used in regional hospitals, while district hospital and health center use both High-Tech and De-Montfort incinerators. About 60% of the incinerators have defective doors. More than 55% of incinerators are corroded in regional and district hospitals. The chimney, top plates and grate which are good condition are 55.6% and 60% in regional hospitals and health centers, respectively. The situation is below 50% in district hospitals. The leakage of the roof and loose structures were observed in district hospitals and health center to be more than 50% of the incinerator houses. On other hand, the performance of burners and incinerator housing cleanliness are generally good. It was concluded that the incinerators in the HCFs are in bad conditions, necessitating maintenance.展开更多
An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindri...An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindrical lithium-ion battery consists of a spring-damping parallel unit.Therefore,a spring-damping parallel unit connecting a damping unit in series is selected to construct the constitutive characteristics of the battery under mechanical abuse.Comparison results show that the equivalent mechanical model can more effectively describe the mechanical properties of the batteries than most cubic fitting models,of which the average relative error of the equivalent mechanical model under different states-of-charge is less than 6.75%.Combined with the proposed equivalent mechanical model,the failure process of the batteries was simulated and analyzed using LS-Dyna and HyperWorks.Under rigid rod tests,failure occurred at the core and bottom of the batteries;under hemispherical punch tests,failure occurred at the core and top,consistent with the experimental results.The average prediction error for the failure displacement under different abuse conditions is less than 4%in the simulations.The equivalent mechanical model requires only a few parameters and can be recognized easily.In the future,the model can be used in safety warning devices based on mechanical penetration.展开更多
文摘Amorphous and nanostructural Fe-B alloys made by mechanical alloying of elemental Fe and amorphous B powders have been studied using X-ray diffraction, differential scanning calorimetry and Mossbauer spectroscopy. It has been shown that the milling conditions have a strong effect on the alloying. The single phase amorphous alloy, which is limited at nominal composition of Fe60B40, has been produced only by milling in Ar atmosphere and in other composition range the mixture of nanostructure Fe-like phase and Fe2B compound with a little amorphous phase are obtained. While by milling in air atmosphere the introduction of oxygen in air may suppress the formation of amorphous phase, thus the compounds Fe2B may be synthesized with no trace of amorphous phase. The crystallization temperatures of amorphous phase in the resultant products are higher than those of a single amorphous alloy Fe60B40, and hardly independent of the milling conditions and the composition. In addition, it is revealed that detectable B content in the final products is lower than the nominal composition of all the initial samples, which indicates that some B atoms may be located in the disordered interfacial regions of the nanostructural alloyed mixtures.
文摘This paper provides analytical diagnosis of mechanical conditions of medical waste incinerators used for healthcare waste (HCW) treatment in Tanzania. The main features assessed were types of incinerators, features of incinerators and incinerator house. The assessment was conducted in three levels of health care facilities (HCFs), that is, Regional, district hospitals and health centers, existed in 26 regions of Tanzania. Questionnaires, interview and checklists were used as tools for data collection. It was observed that High-Tech incinerators are mainly used in regional hospitals, while district hospital and health center use both High-Tech and De-Montfort incinerators. About 60% of the incinerators have defective doors. More than 55% of incinerators are corroded in regional and district hospitals. The chimney, top plates and grate which are good condition are 55.6% and 60% in regional hospitals and health centers, respectively. The situation is below 50% in district hospitals. The leakage of the roof and loose structures were observed in district hospitals and health center to be more than 50% of the incinerator houses. On other hand, the performance of burners and incinerator housing cleanliness are generally good. It was concluded that the incinerators in the HCFs are in bad conditions, necessitating maintenance.
基金Supported by National Key R&D Program of China(Grant No.2017YFB0103801).
文摘An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindrical lithium-ion battery consists of a spring-damping parallel unit.Therefore,a spring-damping parallel unit connecting a damping unit in series is selected to construct the constitutive characteristics of the battery under mechanical abuse.Comparison results show that the equivalent mechanical model can more effectively describe the mechanical properties of the batteries than most cubic fitting models,of which the average relative error of the equivalent mechanical model under different states-of-charge is less than 6.75%.Combined with the proposed equivalent mechanical model,the failure process of the batteries was simulated and analyzed using LS-Dyna and HyperWorks.Under rigid rod tests,failure occurred at the core and bottom of the batteries;under hemispherical punch tests,failure occurred at the core and top,consistent with the experimental results.The average prediction error for the failure displacement under different abuse conditions is less than 4%in the simulations.The equivalent mechanical model requires only a few parameters and can be recognized easily.In the future,the model can be used in safety warning devices based on mechanical penetration.
