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 ev...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
Objective To investigate the feasibility of acquiring the similar homogeneous enhancement using bolus-tracking techniques with shortened respiratory time in prospectively electrocardiogram-gated high-pitch spiral acqu...Objective To investigate the feasibility of acquiring the similar homogeneous enhancement using bolus-tracking techniques with shortened respiratory time in prospectively electrocardiogram-gated high-pitch spiral acquisition mode (Flash mode) coronary computed tomography angiography (CCTA) compared with test bolus technique. Methods One hundred and eighty-four consecutive patients with mean heart rate ≤65 beats per minute undergoing CCTA were prospectively included in this study. The patients were randomly divided into two groups. Patients in the group A (n=92) instructed to shorten respiratory time received CCTA using bolus-tracking technique with high-pitch spiral acquisition mode (Flash mode), while those in the group B (n=92) underwent CCTA with test bolus technique. The attenuation in the ascending aorta, image noise, contrast-to-noise ratio and radiation doses of the two groups were assessed. Results There were no significant differences in the mean attenuation values in the ascending aorta (483.18±59.07 HU vs. 498.7±83.51 HU, P=0.183), image noise (21.4±4.5 HU vs. 20.9±4.3 HU, P=0.414), contrast-to-noise ratio (12.1±4.2 vs. 13.8±5.1, P=0.31) between the groups A and B. There were no significant differences in the radiation dose of dynamic monitoring scans (0.056±0.026 mSv vs. 0.062±0.018 mSv, P=0.068) and radiation dose of angiography (0.94±0.07 mSv vs. 0.96±0.15 mSv,P=0.926) between the two groups, while 15 mL less contrast material volume was administered in the group A than the group B. Conclusion Bolus-tracking technique with shortened time of respiratory in Flash mode of dual-source CT yields the similar homogeneous enhancement with less contrast material in comparison to the test bolus technique.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
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Supported by the Ministry of Science and Technology of Inner Mongolia, China (20110504)
文摘Objective To investigate the feasibility of acquiring the similar homogeneous enhancement using bolus-tracking techniques with shortened respiratory time in prospectively electrocardiogram-gated high-pitch spiral acquisition mode (Flash mode) coronary computed tomography angiography (CCTA) compared with test bolus technique. Methods One hundred and eighty-four consecutive patients with mean heart rate ≤65 beats per minute undergoing CCTA were prospectively included in this study. The patients were randomly divided into two groups. Patients in the group A (n=92) instructed to shorten respiratory time received CCTA using bolus-tracking technique with high-pitch spiral acquisition mode (Flash mode), while those in the group B (n=92) underwent CCTA with test bolus technique. The attenuation in the ascending aorta, image noise, contrast-to-noise ratio and radiation doses of the two groups were assessed. Results There were no significant differences in the mean attenuation values in the ascending aorta (483.18±59.07 HU vs. 498.7±83.51 HU, P=0.183), image noise (21.4±4.5 HU vs. 20.9±4.3 HU, P=0.414), contrast-to-noise ratio (12.1±4.2 vs. 13.8±5.1, P=0.31) between the groups A and B. There were no significant differences in the radiation dose of dynamic monitoring scans (0.056±0.026 mSv vs. 0.062±0.018 mSv, P=0.068) and radiation dose of angiography (0.94±0.07 mSv vs. 0.96±0.15 mSv,P=0.926) between the two groups, while 15 mL less contrast material volume was administered in the group A than the group B. Conclusion Bolus-tracking technique with shortened time of respiratory in Flash mode of dual-source CT yields the similar homogeneous enhancement with less contrast material in comparison to the test bolus technique.
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.
