In order to further simulate the real condition of pavements during the service life,moisture is considered in long-term aging tests based on the existing researches about thermal aging and oxidation aging of asphalt....In order to further simulate the real condition of pavements during the service life,moisture is considered in long-term aging tests based on the existing researches about thermal aging and oxidation aging of asphalt.Water is injected into the pressure aging vessel（PAV）to simulate the aging process during the service life.The performance-based strategic highway research program（SHRP）parameters G/sinδ and S（t）are adopted to evaluate the high-temperature properties and low-temperature properties of the aged asphalt,respectively.The Thailand 90# asphalt,the modified Thailand 90# asphalt and the Shell 70# asphalt are used in the test.It is found that the moisture has a significant influence on parameter G/sinδ when combined with heat and oxygen,so water aging makes high-temperature performance decay more seriously.But the low-temperature performance does not change remarkably after water aging.Since the influences of temperature,oxygen and water are taken into account in the PAV test,the accuracy of asphalt aging tests can be improved and the long-term aging process of asphalt pavement can be exactly simulated.展开更多
Social stock for metal determines secondary or recoverable resources to a certain extent.Top-down analysis method for the studying of metal in social stock was given.Influences of metal consumption under three circums...Social stock for metal determines secondary or recoverable resources to a certain extent.Top-down analysis method for the studying of metal in social stock was given.Influences of metal consumption under three circumstances,that is keeping constant,varying in a linear trend and in an exponential trend,on one kind of metal’s social stock,recyclable ratio and average age were analyzed.Al-contents and Cu-contents in social stock for China during the period 2006-2009 were calculated.The results reveal that Al-contents and Cu-contents in social stock kept increasing and reached 88.9 million tons and 51.4 millions tons in 2009,respectively,their average recyclable ratios are 1.45% and 0.30%,and the average ages are 4.65 years and 6.89 years,respectively.The recyclable ratios and average ages of Al-contents and Cu-contents in social stock will rise in future along with the decline of the increasing rate of aluminum consumption and copper consumption.展开更多
Anthropogenic aluminum cycle in China was analyzed by the aluminum flow diagram based on the life cycle of aluminum products. The whole anthropogenic aluminum cycle consists of four stages： alumina and aluminum produ...Anthropogenic aluminum cycle in China was analyzed by the aluminum flow diagram based on the life cycle of aluminum products. The whole anthropogenic aluminum cycle consists of four stages： alumina and aluminum production, fabrication and manufacture, use and reclamation. Based on the investigation on the 2003-2007 aluminum cycles in China, a number of changes can be found. For instance, resources self-support ratio （RSR） in alumina production dropped from 95.42%to 55.50%, while RSR in the aluminum production increased from 52.45%to 79.25%. However, RSR in the Chinese aluminum industry leveled off at 50%in the period of 2003-2007. The respective use ratios of domestic and imported aluminum scrap in the aluminum industry of 2007 were 5.38% and 9.40%. In contrast, both the net imported Al-containing resources and the lost quantity of Al-containing materials in aluminum cycle increased during the same period, as well as the net increased quantity of Al-containing materials in social stock and recycled Al-scrap. Proposals for promoting aluminum cycle were put forward. The import/export policy and reducing the loss of Al-containing materials for the aluminum industry in China in the future were discussed.展开更多
Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated ...Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use （39.20%） and waste management＆recycling （33.13%）. The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory.展开更多
Aim To study the theory and method for the prediction of service life of solid rocket propellant grain. Methods With the aid of discontiguous diagnostic technology and method of accumulated damage using accelerated...Aim To study the theory and method for the prediction of service life of solid rocket propellant grain. Methods With the aid of discontiguous diagnostic technology and method of accumulated damage using accelerated aging or heat air oven, the aging isotherms for void content versus aging time were determined. According to the principle of time temperature equivalence the viscoelastic master curve for the prediction of service life were obtained. Results and Conclusion The service life of HMX CMDB solid rocket propellant grain were obtained. Because the critical storage life is measured, the accuracy of predicting the service life of the grain has been increased greatly.展开更多
Fatigue failure has long been an important issue for ships and offshore structures. Among the numerous methods for predicting fatigue life, the spectral method is accepted as the most reliable. Although the theory beh...Fatigue failure has long been an important issue for ships and offshore structures. Among the numerous methods for predicting fatigue life, the spectral method is accepted as the most reliable. Although the theory behind spectral analysis is straight-forward, the analysis itself is complicated and time-consuming because it is closely related to critical technical details such as the application of fatigue loading (wave pressures and the inertial forces due to cargoes), the extraction of the stress, and the calculation of stress RAO. Here, four key technical details-loading application, displacement boundary condition, the calculation of stress RAO, and the extraction of the fatigue stress-are discussed thoroughly. For each aspect, a resolution is presented based on the finite element pre-and post-processing software MSC/PATRAN or FE solver MSC/NASTRAN. The resolutions are effective and efficient, which can help engineers perform spectral fatigue analysis accurately and faster.展开更多
Predicting the life of Ni-Cd battery for electric multiple units(EMU)can not only improve the safety and reliability of battery,but also reduce the operating costs of EMU.For this reason,a life prediction method based...Predicting the life of Ni-Cd battery for electric multiple units(EMU)can not only improve the safety and reliability of battery,but also reduce the operating costs of EMU.For this reason,a life prediction method based on linear Wiener process is proposed,which is suitable for both monotonic and non-monotonic degraded systems with accurate results.Firstly,a unary linear Wiener degradation model is established,and the parameters of the model are estimated by using the expectation-maximization algorithm(EM).With the established model,the remaining useful life(RUL)of Ni Cd battery and its distribution are obtained.Then based on the unary Wiener process degradation model,the correlation between capacity and energy is analyzed through Copula function to build a binary linear Wiener degradation model,where its parameters are estimated using Markov Chain Monte Carlo(MCMC)method.Finally,according to the binary Wiener process model,the battery RUL and its distribution are acquired.The experimental results show that the binary linear Wiener degradation model based on capacity and energy possesses higher accuracy than the unary linear wiener process degradation model.展开更多
Pavement performance and economic efficiency are researched on the perpetual test pavement of Yijiang-Suzhou Express Highway in Jiangsu province, China. Test sections were continuously monitored. The conditions and de...Pavement performance and economic efficiency are researched on the perpetual test pavement of Yijiang-Suzhou Express Highway in Jiangsu province, China. Test sections were continuously monitored. The conditions and developing laws of deflection, rutting and cracking are compared among the perpetual pavement with the rich binder layer （RBL）, the perpetual pavement without the RBL, and the conventional semi-rigid asphalt pavement in the past eight years after opening for traffic. Economical evaluation is conducted via life cycle cost analysis （LCCA）. Based on the performance comparison and LCCA analysis, sections with the RBL have good crack resistance, but they are not very satisfactory in the aspect of permanent deformation; the conventional semi-rigid asphalt pavement is the least economic one due to requiring more frequent maintenance. Research results show that the perpetual pavement without RBL is a more appropriate structure for the test site.展开更多
Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degrad...Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.展开更多
The La-Mg-Ni-Co-Al-based AB2-type La0.8-xCe0.2YxMgNi3.4Co0.4Al0.1(x=0,0.05,0.1,0.15,0.2)alloys were prepared via melt spinning.The analyses of the X-ray diffraction(XRD)and scanning electron microscopy(SEM)proved that...The La-Mg-Ni-Co-Al-based AB2-type La0.8-xCe0.2YxMgNi3.4Co0.4Al0.1(x=0,0.05,0.1,0.15,0.2)alloys were prepared via melt spinning.The analyses of the X-ray diffraction(XRD)and scanning electron microscopy(SEM)proved that the experimental alloys contain the main phase LaMgNi4 and the second phase LaNi5.Increasing Y content and spinning rate lead to grain refinement and obvious change of the phase abundance without changing phase composition.Y substitution for La and melt spinning make the life-span of the alloys improved remarkably,which is attributed to the improvement of anti-oxidation,anti-pulverization and anti-corrosion abilities.In addition,the discharge capacity visibly decreases with increasing the Y content,while it firstly increases and then decreases with increasing spinning rate.The electrochemical kinetics increases to the optimum performance and then reduces with increasing spinning rate.Moreover,all the alloys achieve to the highest discharge capacities just at the initial cycle without activation.展开更多
基金The National Natural Science Foundation of China(No.50878054)
文摘In order to further simulate the real condition of pavements during the service life,moisture is considered in long-term aging tests based on the existing researches about thermal aging and oxidation aging of asphalt.Water is injected into the pressure aging vessel（PAV）to simulate the aging process during the service life.The performance-based strategic highway research program（SHRP）parameters G/sinδ and S（t）are adopted to evaluate the high-temperature properties and low-temperature properties of the aged asphalt,respectively.The Thailand 90# asphalt,the modified Thailand 90# asphalt and the Shell 70# asphalt are used in the test.It is found that the moisture has a significant influence on parameter G/sinδ when combined with heat and oxygen,so water aging makes high-temperature performance decay more seriously.But the low-temperature performance does not change remarkably after water aging.Since the influences of temperature,oxygen and water are taken into account in the PAV test,the accuracy of asphalt aging tests can be improved and the long-term aging process of asphalt pavement can be exactly simulated.
基金Project (71003018) supported by the National Natural Science Foundation of ChinaProject (N110402003) supported by the Fundamental Research Funds for the Central Universities,China
文摘Social stock for metal determines secondary or recoverable resources to a certain extent.Top-down analysis method for the studying of metal in social stock was given.Influences of metal consumption under three circumstances,that is keeping constant,varying in a linear trend and in an exponential trend,on one kind of metal’s social stock,recyclable ratio and average age were analyzed.Al-contents and Cu-contents in social stock for China during the period 2006-2009 were calculated.The results reveal that Al-contents and Cu-contents in social stock kept increasing and reached 88.9 million tons and 51.4 millions tons in 2009,respectively,their average recyclable ratios are 1.45% and 0.30%,and the average ages are 4.65 years and 6.89 years,respectively.The recyclable ratios and average ages of Al-contents and Cu-contents in social stock will rise in future along with the decline of the increasing rate of aluminum consumption and copper consumption.
基金Projects (71003018,71373003) supported by the National Natural Science Foundation of ChinaProjects (N110402003,N120302004) supported by the Fundamental Research Funds for the Central Universities,ChinaProject (13YJCZH172) supported by the Ministry of Education of China of Humanities and Social Sciences
文摘Anthropogenic aluminum cycle in China was analyzed by the aluminum flow diagram based on the life cycle of aluminum products. The whole anthropogenic aluminum cycle consists of four stages： alumina and aluminum production, fabrication and manufacture, use and reclamation. Based on the investigation on the 2003-2007 aluminum cycles in China, a number of changes can be found. For instance, resources self-support ratio （RSR） in alumina production dropped from 95.42%to 55.50%, while RSR in the aluminum production increased from 52.45%to 79.25%. However, RSR in the Chinese aluminum industry leveled off at 50%in the period of 2003-2007. The respective use ratios of domestic and imported aluminum scrap in the aluminum industry of 2007 were 5.38% and 9.40%. In contrast, both the net imported Al-containing resources and the lost quantity of Al-containing materials in aluminum cycle increased during the same period, as well as the net increased quantity of Al-containing materials in social stock and recycled Al-scrap. Proposals for promoting aluminum cycle were put forward. The import/export policy and reducing the loss of Al-containing materials for the aluminum industry in China in the future were discussed.
基金Project (41171361) supported by the National Natural Science Foundation of China
文摘Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use （39.20%） and waste management＆recycling （33.13%）. The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory.
文摘Aim To study the theory and method for the prediction of service life of solid rocket propellant grain. Methods With the aid of discontiguous diagnostic technology and method of accumulated damage using accelerated aging or heat air oven, the aging isotherms for void content versus aging time were determined. According to the principle of time temperature equivalence the viscoelastic master curve for the prediction of service life were obtained. Results and Conclusion The service life of HMX CMDB solid rocket propellant grain were obtained. Because the critical storage life is measured, the accuracy of predicting the service life of the grain has been increased greatly.
文摘Fatigue failure has long been an important issue for ships and offshore structures. Among the numerous methods for predicting fatigue life, the spectral method is accepted as the most reliable. Although the theory behind spectral analysis is straight-forward, the analysis itself is complicated and time-consuming because it is closely related to critical technical details such as the application of fatigue loading (wave pressures and the inertial forces due to cargoes), the extraction of the stress, and the calculation of stress RAO. Here, four key technical details-loading application, displacement boundary condition, the calculation of stress RAO, and the extraction of the fatigue stress-are discussed thoroughly. For each aspect, a resolution is presented based on the finite element pre-and post-processing software MSC/PATRAN or FE solver MSC/NASTRAN. The resolutions are effective and efficient, which can help engineers perform spectral fatigue analysis accurately and faster.
基金Project(2017 YFB 1200801-12)supported by the National Natural Science Foundation of China。
文摘Predicting the life of Ni-Cd battery for electric multiple units(EMU)can not only improve the safety and reliability of battery,but also reduce the operating costs of EMU.For this reason,a life prediction method based on linear Wiener process is proposed,which is suitable for both monotonic and non-monotonic degraded systems with accurate results.Firstly,a unary linear Wiener degradation model is established,and the parameters of the model are estimated by using the expectation-maximization algorithm(EM).With the established model,the remaining useful life(RUL)of Ni Cd battery and its distribution are obtained.Then based on the unary Wiener process degradation model,the correlation between capacity and energy is analyzed through Copula function to build a binary linear Wiener degradation model,where its parameters are estimated using Markov Chain Monte Carlo(MCMC)method.Finally,according to the binary Wiener process model,the battery RUL and its distribution are acquired.The experimental results show that the binary linear Wiener degradation model based on capacity and energy possesses higher accuracy than the unary linear wiener process degradation model.
基金The Science and Technology Project of Jiangsu Provincial Communications Department(No.7621000078)
文摘Pavement performance and economic efficiency are researched on the perpetual test pavement of Yijiang-Suzhou Express Highway in Jiangsu province, China. Test sections were continuously monitored. The conditions and developing laws of deflection, rutting and cracking are compared among the perpetual pavement with the rich binder layer （RBL）, the perpetual pavement without the RBL, and the conventional semi-rigid asphalt pavement in the past eight years after opening for traffic. Economical evaluation is conducted via life cycle cost analysis （LCCA）. Based on the performance comparison and LCCA analysis, sections with the RBL have good crack resistance, but they are not very satisfactory in the aspect of permanent deformation; the conventional semi-rigid asphalt pavement is the least economic one due to requiring more frequent maintenance. Research results show that the perpetual pavement without RBL is a more appropriate structure for the test site.
基金Projects(51475462,61374138,61370031)supported by the National Natural Science Foundation of China
文摘Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.
基金Projects(51761032,51471054)supported by the National Natural Science Foundation of ChinaProject(2015MS0558)supported by the Natural Science Foundation of Inner Mongolia,China
文摘The La-Mg-Ni-Co-Al-based AB2-type La0.8-xCe0.2YxMgNi3.4Co0.4Al0.1(x=0,0.05,0.1,0.15,0.2)alloys were prepared via melt spinning.The analyses of the X-ray diffraction(XRD)and scanning electron microscopy(SEM)proved that the experimental alloys contain the main phase LaMgNi4 and the second phase LaNi5.Increasing Y content and spinning rate lead to grain refinement and obvious change of the phase abundance without changing phase composition.Y substitution for La and melt spinning make the life-span of the alloys improved remarkably,which is attributed to the improvement of anti-oxidation,anti-pulverization and anti-corrosion abilities.In addition,the discharge capacity visibly decreases with increasing the Y content,while it firstly increases and then decreases with increasing spinning rate.The electrochemical kinetics increases to the optimum performance and then reduces with increasing spinning rate.Moreover,all the alloys achieve to the highest discharge capacities just at the initial cycle without activation.
