Both the repeated triaxial test （RTT） and the Hamburg wheel tracking test （HWTT） are adopted to evaluate the high temperature performance of the stone mastic asphalt （SMA） and the mastic asphalt （MA）. The corr...Both the repeated triaxial test （RTT） and the Hamburg wheel tracking test （HWTT） are adopted to evaluate the high temperature performance of the stone mastic asphalt （SMA） and the mastic asphalt （MA）. The correlation of the permanent deformations of the MA and the correlation of the deformation developments of the SMA between the two tests are analyzed, respectively. Results show that both the two tests can effectively identify the high temperature performance of mixtures, and the correlation between the final results of the two tests as well as that between the deformation developments of the two tests are excellent with R20.9. In order to further prove the correlation, viscoelastic parameters estimated from the RTT results is used to simulate the rutting development in the HWTT slabs by the finite element method （FEM）. Results indicate that the correlation between the two tests is significant with errors less than 10%. It is suitable to predict the rutting development with the viscoelastic parameters obtained from the RTT.展开更多
The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. ...The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. In this paper, a new method was established to compute the equivalent stress amplitude to evaluate the fatigue damage based on the measurable randomness, since the equivalent stress is the key parameter for assessment of structure fatigue life and load derivation. The equivalent stress amplitude of a high-speed train welded bogie frame was found to obey normal distribution under uniform operation route that verified by on-track dynamic stress data, and the proposed model is, in effect, an improved version of the mathematical model used to calculate the equivalent stress amplitude. The data of a long-term, on-track dynamic stress test program was analyzed to find that the normal distribution parameters of equivalent stress amplitude values differ across different operation route. Thus, the fatigue damage of the high-speed train welded bogie frame can be evaluated by the proposed method if the running schedule of the train is known a priori. The results also showed that the equivalent stress amplitude of the region connected to the power system is more random than in other regions of the bogie frame.展开更多
The rutting resistance of maltilayer asphalt overlay was researched by using laboratoty wheel tracking test.The effects of loading level and test temperature on rutting resistance of asphalt overlay structure were eva...The rutting resistance of maltilayer asphalt overlay was researched by using laboratoty wheel tracking test.The effects of loading level and test temperature on rutting resistance of asphalt overlay structure were evahuaed by means of multilayer specimens.In comparison with multilayer tests,standard specimens of various layers were also conducted to evaluate the rutting resistance.Experimental results indicated that the test tempercature and applied load have a significant effect on rutting resistance of asphalt concrete.Higher test tempercature and heavier applied load resulted in higher rut depths.In addition,the mutilayer wheel tracking test has been demonstrated to be a more reasonable solution in evaluation on rutting resistance of asphatt pavement structure beasuse it reflects the cumulative permanent deformation in all of asphalt layers.展开更多
Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating s...Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex, and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting countermeasures.展开更多
Background: Malaria is a disease of public health concern, which causes significant mortality and morbidity in the tropics, particularly in Africa. Ghana as a country has been implementing a combination of preventive ...Background: Malaria is a disease of public health concern, which causes significant mortality and morbidity in the tropics, particularly in Africa. Ghana as a country has been implementing a combination of preventive and curative interventions as outlined in the Strategic Plan for Malaria Control in Ghana, 2014-2020. Additionally, Ghana subscribes to sub-regional and global initiatives such as the test, treat and track (T3) initiative which seeks to ensure that every suspected malaria case is tested, every case tested positive is treated with the recommended quality-assured antimalarial medicine, and every case treated with antimalarial is followed up to ensure complete parasite clearance. However, the implementation of this policy is a challenge, hence the need to study provider adherence to the testing, treating, and tracking. Materials and method: The study is cross-sectional in nature and data for this research was collected from consulting room registers, patients’ folders, the District Health Information Management System and a structured questionnaire designed to interview healthcare providers. The data was exported into Stata for cleaning and analysis. The results of the study were presented in the form of statistical charts and tables. Results: The study revealed that generally, provider adherence to the T3 policy was encouraging in the Binduri district, and a high level of testing (100%) of suspected malaria cases eliminated the practice of presumptive treatment. However, tracking of patients (68.2%) was not as high as testing and treatment which was revealed by the number asked to return for a review during the folder review. Conclusion: Significant progress in clinicians’ adherence to policy on malaria case management (T3) in the Binduri District. Continued training and facilitative supervision are essential to sustain gains and close existing gaps in clinicians’ adherence to malaria case management policy.展开更多
This paper describes the required testing and approval procedures of new track systems operated in Europe. To begin with, test methods and performance specifications according to European Standard （EN） are outlined....This paper describes the required testing and approval procedures of new track systems operated in Europe. To begin with, test methods and performance specifications according to European Standard （EN） are outlined. These include the repeated loading test, the determination of the static and dynamic stiffness of rail pads, clamping force and longitudinal rail resistance. The fact that labor tests are unable to simulate all the conditions in situ shows that these labor tests are not sufficient for the evaluation of the long term behaviour of a new track system： a test track of sufficient length must be constructed and exposed to traffic loads. In Europe to be accredited as a new system, a new slab track system must have a trial time of more than two years, during which the features of the whole system can be recognized. In the second part of this paper, the experience of the Institute of Road, Railway and Airfield Construction of TUM concerning the measuring methods of slab track systems carrying traffic are outlined. Also the approval procedure of the new slab tracks in Germany is discussed.展开更多
A prototype thick-GEM-based cooling storage ring external-target experiment(CEE) time projection chamber(TPC) is constructed and tested with the pulsed ultraviolet laser beams. The results indicate that the prototype ...A prototype thick-GEM-based cooling storage ring external-target experiment(CEE) time projection chamber(TPC) is constructed and tested with the pulsed ultraviolet laser beams. The results indicate that the prototype TPC has a good performance in three-dimensional track resolution. In X direction the position resolution is about 0.2 mm, and in Y direction the position resolution is about 0.5 mm. The results also determine that the energy resolution is about 5.4%, which achieve the requirements of the CEE experiment and can be used to study the nuclear state equation and the quantum chromo dynamics.展开更多
基金The Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry (No.6821001005)
文摘Both the repeated triaxial test （RTT） and the Hamburg wheel tracking test （HWTT） are adopted to evaluate the high temperature performance of the stone mastic asphalt （SMA） and the mastic asphalt （MA）. The correlation of the permanent deformations of the MA and the correlation of the deformation developments of the SMA between the two tests are analyzed, respectively. Results show that both the two tests can effectively identify the high temperature performance of mixtures, and the correlation between the final results of the two tests as well as that between the deformation developments of the two tests are excellent with R20.9. In order to further prove the correlation, viscoelastic parameters estimated from the RTT results is used to simulate the rutting development in the HWTT slabs by the finite element method （FEM）. Results indicate that the correlation between the two tests is significant with errors less than 10%. It is suitable to predict the rutting development with the viscoelastic parameters obtained from the RTT.
基金Supported by National Key Research and Development Program of China(Grant No.2018YFB1201704)National Natural Science Foundation of China(Major Program,Grant No.11790281)
文摘The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. In this paper, a new method was established to compute the equivalent stress amplitude to evaluate the fatigue damage based on the measurable randomness, since the equivalent stress is the key parameter for assessment of structure fatigue life and load derivation. The equivalent stress amplitude of a high-speed train welded bogie frame was found to obey normal distribution under uniform operation route that verified by on-track dynamic stress data, and the proposed model is, in effect, an improved version of the mathematical model used to calculate the equivalent stress amplitude. The data of a long-term, on-track dynamic stress test program was analyzed to find that the normal distribution parameters of equivalent stress amplitude values differ across different operation route. Thus, the fatigue damage of the high-speed train welded bogie frame can be evaluated by the proposed method if the running schedule of the train is known a priori. The results also showed that the equivalent stress amplitude of the region connected to the power system is more random than in other regions of the bogie frame.
基金Funded by Science and Technology Key Project of Hubei Prov-ince(No.2005361)
文摘The rutting resistance of maltilayer asphalt overlay was researched by using laboratoty wheel tracking test.The effects of loading level and test temperature on rutting resistance of asphalt overlay structure were evahuaed by means of multilayer specimens.In comparison with multilayer tests,standard specimens of various layers were also conducted to evaluate the rutting resistance.Experimental results indicated that the test tempercature and applied load have a significant effect on rutting resistance of asphalt concrete.Higher test tempercature and heavier applied load resulted in higher rut depths.In addition,the mutilayer wheel tracking test has been demonstrated to be a more reasonable solution in evaluation on rutting resistance of asphatt pavement structure beasuse it reflects the cumulative permanent deformation in all of asphalt layers.
基金Project supported by the National Natural Science Foundation of China (No. 51008017)the Fundamental Research Funds for the Central Universities of China (Nos. 2009JBM074 and 2009JBM075)
文摘Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex, and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting countermeasures.
文摘Background: Malaria is a disease of public health concern, which causes significant mortality and morbidity in the tropics, particularly in Africa. Ghana as a country has been implementing a combination of preventive and curative interventions as outlined in the Strategic Plan for Malaria Control in Ghana, 2014-2020. Additionally, Ghana subscribes to sub-regional and global initiatives such as the test, treat and track (T3) initiative which seeks to ensure that every suspected malaria case is tested, every case tested positive is treated with the recommended quality-assured antimalarial medicine, and every case treated with antimalarial is followed up to ensure complete parasite clearance. However, the implementation of this policy is a challenge, hence the need to study provider adherence to the testing, treating, and tracking. Materials and method: The study is cross-sectional in nature and data for this research was collected from consulting room registers, patients’ folders, the District Health Information Management System and a structured questionnaire designed to interview healthcare providers. The data was exported into Stata for cleaning and analysis. The results of the study were presented in the form of statistical charts and tables. Results: The study revealed that generally, provider adherence to the T3 policy was encouraging in the Binduri district, and a high level of testing (100%) of suspected malaria cases eliminated the practice of presumptive treatment. However, tracking of patients (68.2%) was not as high as testing and treatment which was revealed by the number asked to return for a review during the folder review. Conclusion: Significant progress in clinicians’ adherence to policy on malaria case management (T3) in the Binduri District. Continued training and facilitative supervision are essential to sustain gains and close existing gaps in clinicians’ adherence to malaria case management policy.
文摘This paper describes the required testing and approval procedures of new track systems operated in Europe. To begin with, test methods and performance specifications according to European Standard （EN） are outlined. These include the repeated loading test, the determination of the static and dynamic stiffness of rail pads, clamping force and longitudinal rail resistance. The fact that labor tests are unable to simulate all the conditions in situ shows that these labor tests are not sufficient for the evaluation of the long term behaviour of a new track system： a test track of sufficient length must be constructed and exposed to traffic loads. In Europe to be accredited as a new system, a new slab track system must have a trial time of more than two years, during which the features of the whole system can be recognized. In the second part of this paper, the experience of the Institute of Road, Railway and Airfield Construction of TUM concerning the measuring methods of slab track systems carrying traffic are outlined. Also the approval procedure of the new slab tracks in Germany is discussed.
基金supported by the National Key Research and Development Program of China(Nos.2016YFA0400502 and 2015CB856904)the National Natural Science Foundation of China(Nos.U1332129,11475243,11421505,11775288 and 11405005)the ‘‘100-talent plan’’ of Shanghai Institute of Applied Physics from the Chinese Academy of Sciences(Nos.Y290061011 and Y526011011)
文摘A prototype thick-GEM-based cooling storage ring external-target experiment(CEE) time projection chamber(TPC) is constructed and tested with the pulsed ultraviolet laser beams. The results indicate that the prototype TPC has a good performance in three-dimensional track resolution. In X direction the position resolution is about 0.2 mm, and in Y direction the position resolution is about 0.5 mm. The results also determine that the energy resolution is about 5.4%, which achieve the requirements of the CEE experiment and can be used to study the nuclear state equation and the quantum chromo dynamics.
