When conducting dynamic tests of underground structure by a rigid container, reasonable boundary conditions are one of the essential factors related to the accuracy of test results, especially the artificial boundary ...When conducting dynamic tests of underground structure by a rigid container, reasonable boundary conditions are one of the essential factors related to the accuracy of test results, especially the artificial boundary perpendicular to the excitation direction. On the basis of numerous studies, shaking table tests with four different typical boundaries are performed in this study. The tests consider the seismic intensity and seismic wave types. Then, the simulation effects of the four boundary conditions are evaluated from four aspects as follows: the differential rate of peak acceleration, acceleration curve, similarity of Fourier frequency spectra, and uneven soil settlement in rigid containers. Results show that the simulation effects of the boundary conditions are not only affected by the nature of the boundary material but also related to the seismic intensity, types of seismic waves, and filter characteristic of the filling medium in containers. In comparison with the other three types of boundary condition, foamed polyethylene shows the best simulation effect and its effect decreases gradually with the increase in earthquake intensity. Finally, on the basis of existing studies, the evaluation criteria of boundary effect, the principle for the selection of boundary material type and the thickness of boundary material are discussed and summarized, and the corresponding design methods and suggestions are then provided.展开更多
Intermodal containers have many advantages in the bulk supply chain, but idle times may cause freezing problems for containers in terminals and long-lasting deliveries, especially during the winter time in Nordic cond...Intermodal containers have many advantages in the bulk supply chain, but idle times may cause freezing problems for containers in terminals and long-lasting deliveries, especially during the winter time in Nordic conditions. The aim of the cold tests was to study metal and composite containers’ ability to tolerate wood chips freezing into the inner surface of the container. Two of the containers were normal metal containers and one was a composite container. The loaded containers were put inside the laboratory hall, the temperature of which was -30°C, and kept there for variable times: less than 24 hours. The inner surface of one of metal containers was treated with a special coolant, EC1. After the test, the chips were unloaded, and the container walls were checked to determine whether there was any material left on them. The test results indicated the advantages of composite containers having a thermally insulated structure without freezing problems. At the same time, chips were freezing badly onto the floor of both metal containers. A frozen chip layer with a thickness of approximately 50 cm - 60 cm was stuck to the floors. As such, EC1 did not seem to prevent the freezing of the chips onto the inner surfaces. The results proved that intermodal logistics of truck and train transportation would be more suitable for composite containers than for metal containers in the winter time in Nordic conditions.展开更多
Aimed at the current treatment status of the polymer-flooding wastewater in Bohai oilfield, electrochemical technology used for polymer-degradation and oil-removal was researched. It formed the process flow of cyclone...Aimed at the current treatment status of the polymer-flooding wastewater in Bohai oilfield, electrochemical technology used for polymer-degradation and oil-removal was researched. It formed the process flow of cyclone mixed dosing → electrochemical removal oil → inclined tube removal oil → walnut shell filter, and a set of skid mounted wastewater containing polymer treatment plant was designed and manufactured, which was used for the field test of electrochemical treatment of wastewater containing polymer in offshore oilfield. The result shows that the oil removal rate of the electrochemical treatment process is over 98%, and the synergistic effect is significant especially used in conjunction with water clarifier of BHQ-04. When the amount of water clarifier is 50 - 150 mg/L, the oil content, the median particle diameter and the suspended solids content of the filtered water is 8 - 18 mg/L, 1.9 - 2.26 μm and 1.39 - 2.04 mg/L respectively, which reach the scene water quality standards for water injection.展开更多
Macao,a special administrative region(SAR)of the People’s Republic of China,is located in southern China and shares the border with China's Mainland.It is the most densely populated region in the world,with a pop...Macao,a special administrative region(SAR)of the People’s Republic of China,is located in southern China and shares the border with China's Mainland.It is the most densely populated region in the world,with a population of 667400 and a total land area of 32.9 square kilometers in 2019.Since the first case diagnosed on January 22,2020,there was a total of 45 laboratory-confirmed coronavirus disease 2019(COVID-19)cases in Macao,of which 43 patients(96%)were imported cases.To date,all patients had been discharged successfully from Centro Hospitalar Conde de São Januário,a designated hospital to manage all COVID-19 patients in Macao.Eventually,no patient died,and no local community outbreak was noted.This opinion review describes the underlying factors that could have contributed to the successful experience in Macao SAR,China,which include the following:(1)Early implementation of containment measures;(2)Large-scale quarantine using hotel rooms to reduce the risk of a local outbreak;and(3)Multidisciplinary co-operation and transparency of information to the public.Although the successful experience in Macao SAR,China,may not be generalized to other regions,it should not be unreasonable to be well prepared with sufficient logistic support to conduct timely containment and early detection of episodic cases to prevent the backsliding of COVID-19 outbreak.展开更多
A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing b...A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing behavior without precedent cyclic-loading histories of sands containing crushed mudstone.The tested materials with a main particle diameter of 2-0.85 mm were prepared by mixing sands and crushed mudstone to reach the prescribed mudstone content defined by dry mass ranging from 0% to 50%.The mixtures were subjected to immersion under a certain stress level and were subsequently tested.In addition,one-dimensional compression tests were also supplementally performed to visually observe the immersion-induced degradation of crushed mudstone.The test results mainly showed that: (1) the liquefaction resistance,the post-liquefaction undrained strength,and the undrained strength without a precedent cyclic-loading history decreased significantly with increasing mudstone content,M c ,up to 20%;(2) even a small amount of crushed mudstone affected these strengths;(3) the above-mentioned large reductions in the strengths were attributed to the immersion-induced degradation of crushed mudstone;(4) at M_(c) >20%,the liquefaction resistance increased while the significant increase in the undrained static strengths with and without precedent cyclic-loading histories was not observed;and (5) the increase in the liquefaction resistance at M_(c) >20% may have been attributed to both the gradual increase in the plasticity and the formation of the soil aggregates among deteriorated crushed mudstone,while the increase in the specimen density did not play an important role in such behavior.展开更多
基金Projects(51978669,U1734208)supported by the National Natural Science Foundation of ChinaProject(2018JJ3657)supported by the Natural Science Foundation of Hunan Province,China
文摘When conducting dynamic tests of underground structure by a rigid container, reasonable boundary conditions are one of the essential factors related to the accuracy of test results, especially the artificial boundary perpendicular to the excitation direction. On the basis of numerous studies, shaking table tests with four different typical boundaries are performed in this study. The tests consider the seismic intensity and seismic wave types. Then, the simulation effects of the four boundary conditions are evaluated from four aspects as follows: the differential rate of peak acceleration, acceleration curve, similarity of Fourier frequency spectra, and uneven soil settlement in rigid containers. Results show that the simulation effects of the boundary conditions are not only affected by the nature of the boundary material but also related to the seismic intensity, types of seismic waves, and filter characteristic of the filling medium in containers. In comparison with the other three types of boundary condition, foamed polyethylene shows the best simulation effect and its effect decreases gradually with the increase in earthquake intensity. Finally, on the basis of existing studies, the evaluation criteria of boundary effect, the principle for the selection of boundary material type and the thickness of boundary material are discussed and summarized, and the corresponding design methods and suggestions are then provided.
文摘Intermodal containers have many advantages in the bulk supply chain, but idle times may cause freezing problems for containers in terminals and long-lasting deliveries, especially during the winter time in Nordic conditions. The aim of the cold tests was to study metal and composite containers’ ability to tolerate wood chips freezing into the inner surface of the container. Two of the containers were normal metal containers and one was a composite container. The loaded containers were put inside the laboratory hall, the temperature of which was -30°C, and kept there for variable times: less than 24 hours. The inner surface of one of metal containers was treated with a special coolant, EC1. After the test, the chips were unloaded, and the container walls were checked to determine whether there was any material left on them. The test results indicated the advantages of composite containers having a thermally insulated structure without freezing problems. At the same time, chips were freezing badly onto the floor of both metal containers. A frozen chip layer with a thickness of approximately 50 cm - 60 cm was stuck to the floors. As such, EC1 did not seem to prevent the freezing of the chips onto the inner surfaces. The results proved that intermodal logistics of truck and train transportation would be more suitable for composite containers than for metal containers in the winter time in Nordic conditions.
文摘Aimed at the current treatment status of the polymer-flooding wastewater in Bohai oilfield, electrochemical technology used for polymer-degradation and oil-removal was researched. It formed the process flow of cyclone mixed dosing → electrochemical removal oil → inclined tube removal oil → walnut shell filter, and a set of skid mounted wastewater containing polymer treatment plant was designed and manufactured, which was used for the field test of electrochemical treatment of wastewater containing polymer in offshore oilfield. The result shows that the oil removal rate of the electrochemical treatment process is over 98%, and the synergistic effect is significant especially used in conjunction with water clarifier of BHQ-04. When the amount of water clarifier is 50 - 150 mg/L, the oil content, the median particle diameter and the suspended solids content of the filtered water is 8 - 18 mg/L, 1.9 - 2.26 μm and 1.39 - 2.04 mg/L respectively, which reach the scene water quality standards for water injection.
文摘Macao,a special administrative region(SAR)of the People’s Republic of China,is located in southern China and shares the border with China's Mainland.It is the most densely populated region in the world,with a population of 667400 and a total land area of 32.9 square kilometers in 2019.Since the first case diagnosed on January 22,2020,there was a total of 45 laboratory-confirmed coronavirus disease 2019(COVID-19)cases in Macao,of which 43 patients(96%)were imported cases.To date,all patients had been discharged successfully from Centro Hospitalar Conde de São Januário,a designated hospital to manage all COVID-19 patients in Macao.Eventually,no patient died,and no local community outbreak was noted.This opinion review describes the underlying factors that could have contributed to the successful experience in Macao SAR,China,which include the following:(1)Early implementation of containment measures;(2)Large-scale quarantine using hotel rooms to reduce the risk of a local outbreak;and(3)Multidisciplinary co-operation and transparency of information to the public.Although the successful experience in Macao SAR,China,may not be generalized to other regions,it should not be unreasonable to be well prepared with sufficient logistic support to conduct timely containment and early detection of episodic cases to prevent the backsliding of COVID-19 outbreak.
基金financially supported by JSPS KAKENHI Grant Number JP19K15083.
文摘A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing behavior without precedent cyclic-loading histories of sands containing crushed mudstone.The tested materials with a main particle diameter of 2-0.85 mm were prepared by mixing sands and crushed mudstone to reach the prescribed mudstone content defined by dry mass ranging from 0% to 50%.The mixtures were subjected to immersion under a certain stress level and were subsequently tested.In addition,one-dimensional compression tests were also supplementally performed to visually observe the immersion-induced degradation of crushed mudstone.The test results mainly showed that: (1) the liquefaction resistance,the post-liquefaction undrained strength,and the undrained strength without a precedent cyclic-loading history decreased significantly with increasing mudstone content,M c ,up to 20%;(2) even a small amount of crushed mudstone affected these strengths;(3) the above-mentioned large reductions in the strengths were attributed to the immersion-induced degradation of crushed mudstone;(4) at M_(c) >20%,the liquefaction resistance increased while the significant increase in the undrained static strengths with and without precedent cyclic-loading histories was not observed;and (5) the increase in the liquefaction resistance at M_(c) >20% may have been attributed to both the gradual increase in the plasticity and the formation of the soil aggregates among deteriorated crushed mudstone,while the increase in the specimen density did not play an important role in such behavior.
