One quarter scale experiment device of a typical L-shape architecture structure including a burning room and an adjacent hallway is established to carry out the research.The smoke characteristics at the sampling point...One quarter scale experiment device of a typical L-shape architecture structure including a burning room and an adjacent hallway is established to carry out the research.The smoke characteristics at the sampling points below the ceiling of the burning compartment and the roof of the hallway are studied systematically to find out the effects of different ceilings on the local fire origin compartment and the smoke transportation to a remote area.A series of tests is reported and the smoke residence time,the concentration peak and the concentration build up rate are investigated as functions of the type of the ceiling.The smoke residence time,the most important factor concerning smoke toxicity,is described by a novel concept,wavelength,in this study.Furthermore,it is worth emphasizing that the PVC ceiling exhibits a phenomenon of frequent collapse during the fire developing period.The single heat action is conducted to judge the smoke and the heat effect on the fire risk.展开更多
Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely u...Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.展开更多
The architectural?complexes?of Hasan Basha Tahir?were suffering from many damages and deformation in different elements as load bearing walls, arches and wooden ceiling. Ground water, salt weathering, air pollution, b...The architectural?complexes?of Hasan Basha Tahir?were suffering from many damages and deformation in different elements as load bearing walls, arches and wooden ceiling. Ground water, salt weathering, air pollution, biological colonization and environmental aspects were the main degradation factors which caused a lot of damage and deterioration phenomena in the complexes. Horizontal and vertical cracks, salts, loss of decorations, and featured dark of the stone surface were noticed at the complexes elements. In addition, the celling of the complex was in a very bad condition;?it had lost a lot of decoration elements, cracking, soot deposition, insects’ holes, and fungi growth. This research will discuss the various deterioration phenomena that?have?effect on the main building materials and cause the damages and discuss the general scientific methodology of the architectural and structural conservation project which was?carried out.展开更多
The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morpholog...The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morphology of the gecko toes was recorded by a high speed camera.The study aims to understand the relationship between adhesive and shear forces generated by the toes of the gecko and the locomotion behavior when it walks on walls and ceilings.Results showed that shear force is along the toe-only 12.6° and 3.1° away from the toe for wall-climbing and ceiling-crawling,respectively while the adhesion is big enough to balance the body weight and moment.The shear forces generated by the first and the fifth toes are in opposite directions;this redundant force increases the reliability of adhesion and stability of locomotion.The support angles of toes are equal approximately for ceiling-crawling and wall-climbing.The study greatly inspires the design of a gecko-like robot.展开更多
After the decoupling of the US dollar from gold in 1971,US Treasuries replaced gold as the value benchmark of the international monetary system and acquired an exorbitant privilege.Subsequently,the total amount of US ...After the decoupling of the US dollar from gold in 1971,US Treasuries replaced gold as the value benchmark of the international monetary system and acquired an exorbitant privilege.Subsequently,the total amount of US debt exhibited an exponential expansion trend,unbound by any substantial constraints.The so-called debt ceiling is a partisan game rather than a rigid fiscal constraint on the United States.As long as there are no fundamental changes in the global monetary system,the international credit of US Treasuries will stay stable,and their trend of infinite expansion will be sustained.Massive quantitative easing policies have failed to significantly shake this stability,and the notion of global investors offloading US Treasuries is more an illusion than a fact.The exorbitant privilege of US Treasuries grants its federal government the“freedom to borrow,”shielding the American financial sector from due penalties during global financial crises and securing excessive returns in global capital cycles.In the old days when running“twin surpluses”on capital and current accounts,China kept the value of Renminbi low to support its export manufacturing sector along the southeast coast.As a result,China accumulated huge foreign exchange reserves,mainly US Treasuries.Nowadays,this practice is no longer necessary,yielding low returns and posing significant security risks.展开更多
A non-noble metal oxygen reduction reaction （ORR） catalyst labeled as Co-C-N（800） was synthesized by heat-treating a mixture of urea, cobalt chloride and acetylene black for 2 h at 800 ℃ in an inert nitrogen atmo...A non-noble metal oxygen reduction reaction （ORR） catalyst labeled as Co-C-N（800） was synthesized by heat-treating a mixture of urea, cobalt chloride and acetylene black for 2 h at 800 ℃ in an inert nitrogen atmosphere. X-ray diffraction pattern indicates that a metallic β-Co is generated after the heat-treating process. The results from cyclic voltammograms show that the obtained Co-C-N（800） catalyst has good ORR catalytic activity in 0.5 mol/L H2SO4 solution. The catalyst is also good at methanol tolerance and stability in the acidic solution.展开更多
This paper summarizes the research on non-structural elements and building contents being conducted at University of Canterbury in New Zealand. Since the 2010-2011 series of Canterbury earthquakes, in which damage to ...This paper summarizes the research on non-structural elements and building contents being conducted at University of Canterbury in New Zealand. Since the 2010-2011 series of Canterbury earthquakes, in which damage to non-structural components and contents contributed heavily to downtime and overall financial loss, attention to seismic performance and design of non-structural components and contents in buildings has increased exponentially in NZ. This has resulted in an increased allocation of resources to research leading to development of more resilient non-structural systems in buildings that would incur substantially less damage and cause little downtime during earthquakes. In the last few years, NZ researchers have made important developments in understanding and improving the seismic performance of secondary building elements such as partitions, facades, ceilings and contents.展开更多
文摘One quarter scale experiment device of a typical L-shape architecture structure including a burning room and an adjacent hallway is established to carry out the research.The smoke characteristics at the sampling points below the ceiling of the burning compartment and the roof of the hallway are studied systematically to find out the effects of different ceilings on the local fire origin compartment and the smoke transportation to a remote area.A series of tests is reported and the smoke residence time,the concentration peak and the concentration build up rate are investigated as functions of the type of the ceiling.The smoke residence time,the most important factor concerning smoke toxicity,is described by a novel concept,wavelength,in this study.Furthermore,it is worth emphasizing that the PVC ceiling exhibits a phenomenon of frequent collapse during the fire developing period.The single heat action is conducted to judge the smoke and the heat effect on the fire risk.
基金Research fund for earthquake engineering of China Earthquake Administration(201508023)a project of the National Science&Technology Support Program during the Twelfth Five-year Plan Period of China(2015BAK17B03)a general program of National Natural Science Foundation of China(51578515)
文摘Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.
文摘The architectural?complexes?of Hasan Basha Tahir?were suffering from many damages and deformation in different elements as load bearing walls, arches and wooden ceiling. Ground water, salt weathering, air pollution, biological colonization and environmental aspects were the main degradation factors which caused a lot of damage and deterioration phenomena in the complexes. Horizontal and vertical cracks, salts, loss of decorations, and featured dark of the stone surface were noticed at the complexes elements. In addition, the celling of the complex was in a very bad condition;?it had lost a lot of decoration elements, cracking, soot deposition, insects’ holes, and fungi growth. This research will discuss the various deterioration phenomena that?have?effect on the main building materials and cause the damages and discuss the general scientific methodology of the architectural and structural conservation project which was?carried out.
基金supported by the National High Technology Research and Development Program of China ("863" Program)(Grant No. 2007AA04Z201)National Natural Science Foundation of China (Grant Nos. 60535020,60910007,30770285,30700068)
文摘The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morphology of the gecko toes was recorded by a high speed camera.The study aims to understand the relationship between adhesive and shear forces generated by the toes of the gecko and the locomotion behavior when it walks on walls and ceilings.Results showed that shear force is along the toe-only 12.6° and 3.1° away from the toe for wall-climbing and ceiling-crawling,respectively while the adhesion is big enough to balance the body weight and moment.The shear forces generated by the first and the fifth toes are in opposite directions;this redundant force increases the reliability of adhesion and stability of locomotion.The support angles of toes are equal approximately for ceiling-crawling and wall-climbing.The study greatly inspires the design of a gecko-like robot.
文摘After the decoupling of the US dollar from gold in 1971,US Treasuries replaced gold as the value benchmark of the international monetary system and acquired an exorbitant privilege.Subsequently,the total amount of US debt exhibited an exponential expansion trend,unbound by any substantial constraints.The so-called debt ceiling is a partisan game rather than a rigid fiscal constraint on the United States.As long as there are no fundamental changes in the global monetary system,the international credit of US Treasuries will stay stable,and their trend of infinite expansion will be sustained.Massive quantitative easing policies have failed to significantly shake this stability,and the notion of global investors offloading US Treasuries is more an illusion than a fact.The exorbitant privilege of US Treasuries grants its federal government the“freedom to borrow,”shielding the American financial sector from due penalties during global financial crises and securing excessive returns in global capital cycles.In the old days when running“twin surpluses”on capital and current accounts,China kept the value of Renminbi low to support its export manufacturing sector along the southeast coast.As a result,China accumulated huge foreign exchange reserves,mainly US Treasuries.Nowadays,this practice is no longer necessary,yielding low returns and posing significant security risks.
文摘A non-noble metal oxygen reduction reaction （ORR） catalyst labeled as Co-C-N（800） was synthesized by heat-treating a mixture of urea, cobalt chloride and acetylene black for 2 h at 800 ℃ in an inert nitrogen atmosphere. X-ray diffraction pattern indicates that a metallic β-Co is generated after the heat-treating process. The results from cyclic voltammograms show that the obtained Co-C-N（800） catalyst has good ORR catalytic activity in 0.5 mol/L H2SO4 solution. The catalyst is also good at methanol tolerance and stability in the acidic solution.
基金co-funded by the University of Canterbury,Natural Hazards Platform (NHP)the Ministry of Business,Innovation and Employment (MBIE),New Zealand
文摘This paper summarizes the research on non-structural elements and building contents being conducted at University of Canterbury in New Zealand. Since the 2010-2011 series of Canterbury earthquakes, in which damage to non-structural components and contents contributed heavily to downtime and overall financial loss, attention to seismic performance and design of non-structural components and contents in buildings has increased exponentially in NZ. This has resulted in an increased allocation of resources to research leading to development of more resilient non-structural systems in buildings that would incur substantially less damage and cause little downtime during earthquakes. In the last few years, NZ researchers have made important developments in understanding and improving the seismic performance of secondary building elements such as partitions, facades, ceilings and contents.
