Experiments of de-ionized water flowing in microchannels made in copper blocks were carried out to obtain pressure drop and friction factor and to investigate any possible discrepancies from conventional theory. Three...Experiments of de-ionized water flowing in microchannels made in copper blocks were carried out to obtain pressure drop and friction factor and to investigate any possible discrepancies from conventional theory. Three channels with widths of 0.5 mm, 1.0 mm, 1.71 mm, a depth of 0.39 mm and a length of 62 mm were tested. For adiabatic tests, the temperature of the working fluid was maintained at 30 ℃, 60 ℃ and 90 ℃ without any heat fluxes supplied to the test section. The experimental conditions covered a range of Reynolds numbers from 234 to 3,430. For non-adiabatic tests, the inlet temperature and heat flux applied were 30 ℃ and 147 kW/m2 and only for the 0.635 mm channel. The friction factors obtained for the widest channel （Dh = 0.635 mm） are reported for both adiabatic and non-adiabatic experiments to assess possible temperature effects. The paper focuses on the effect of hydraulic diameter on pressure drop and friction factor over the experimental conditions. The pressure drop was found to decrease as the inlet temperature was increased, while the friction factors for the three test sections did not show significant differences. The experimental friction factors were in reasonable agreement with conventional developing flow theory. The effect of temperature on friction factor was not considerable as the friction factor with and without heat flux was almost the same.展开更多
C. taylorii （Chrysophaeum taylorii） Lewis and Bryan （Pelagophyceae） are benthic mucilage-producing microalgae recently recorded in the Mediterranean Sea, where its summer blooms are having detrimental effects on b...C. taylorii （Chrysophaeum taylorii） Lewis and Bryan （Pelagophyceae） are benthic mucilage-producing microalgae recently recorded in the Mediterranean Sea, where its summer blooms are having detrimental effects on benthic communities, fisheries and tourism, especially along the Sardinian coasts （western Mediterranean Sea）. Although few informations on the bloom dynamics of this microalga are available in literature jet, recent studies have hypothesized that sea water temperature plays a major role in determining the distribution and abundance of C. taylorii. The goal of this pilot study was to verify the above-mentioned statement providing experimental evidence for it. To this purpose, C. taylorii presence and abundance were investigated along a temperature gradient near the powerhouse of Torre Valdaliga （Latium coasts）, where a stream of hot water is continuously pumped out from the powerhouse into the sea. The obtained data showed that C. taylorii abundance was significantly higher in the study sites nearer to the powerhouse and a positive correlation between water temperature and cell densities was found, thus confirming that water temperature is one of the environmental variables directly influencing the bloom dynamics of this microalga in the Mediterranean Sea.展开更多
In order to fulfil the microgravity requirements for space experiments, improved technology for the microgravity environment is proposed, including that for raising the orbital altitude, optimizing the layout of the d...In order to fulfil the microgravity requirements for space experiments, improved technology for the microgravity environment is proposed, including that for raising the orbital altitude, optimizing the layout of the disturbance source, using IN-thrusters instead of 5 N-thrusters, etc. In addition, evaluation of the microgravity environment of the recoverable satellite was also conducted using on-orbit micro-vibration measurement, on-orbit experiment and data analysis technologies. The microgravity level of the SJ-l0 recoverable satellite in China is compared with the spacecraft used for carrying out space science experiments internationally. This paper describes the microgravity environment of the SJ- 10 recoverable satellite, and its importance for analysing space experimental results.展开更多
The orientation of the dimple increases the flow distance in the dimple and produces fluid cumulative effect in the dimple length direction, which leads to obvious hydrodynamic effect as a result. In order to investig...The orientation of the dimple increases the flow distance in the dimple and produces fluid cumulative effect in the dimple length direction, which leads to obvious hydrodynamic effect as a result. In order to investigate the hydrodynamic effect of orientation dimples, a series of experiments was carried out on a ring-on-ring test. Multi-pored faces were tested with different dimple inclination angles and slender ratios. Film thickness and frictional torque were measured under different conditions of load and rotation speed. Experimental results showed that the orientation dimple could produce obvious dynamic effect by change of the flow direction and the increasing dimple orientation leads to increase of the load capability. The hydrodynamic effect strongly depends on dimple orientation parameters such as inclination angle and slender ratio. A larger load capability can be available by increasing dimple orientation and rotation speed. Experimental results agreed well with the theory that orientation micro-pores can significantly improve hydrodynamic performance of surfaces.展开更多
The aim of the Daya Bay reactor antineutrino experiment is to determine the neutrino mixing angle 813 with a sensitivity of 0.01 or better at 90% confidence level. In order to improve the position resolution of both t...The aim of the Daya Bay reactor antineutrino experiment is to determine the neutrino mixing angle 813 with a sensitivity of 0.01 or better at 90% confidence level. In order to improve the position resolution of both the positron interaction and the neu- tron capture, the inside of the antineutrino detectors should be as unreflecting as possible. A black matt fluorocarbon paint is coated on the inner surface of the detectors made of 304L stainless steel to meet the physical requirement. This paint is com- patible with mineral oil, has low radioactivity, is easy to spray and fast curing at normal temperatures. The coating has excel- lent performance such as good adhesive force, uniformity, compact, scratch and wear resistance, and so on. It is the first appli- cation of such paint to large physical devices.展开更多
文摘Experiments of de-ionized water flowing in microchannels made in copper blocks were carried out to obtain pressure drop and friction factor and to investigate any possible discrepancies from conventional theory. Three channels with widths of 0.5 mm, 1.0 mm, 1.71 mm, a depth of 0.39 mm and a length of 62 mm were tested. For adiabatic tests, the temperature of the working fluid was maintained at 30 ℃, 60 ℃ and 90 ℃ without any heat fluxes supplied to the test section. The experimental conditions covered a range of Reynolds numbers from 234 to 3,430. For non-adiabatic tests, the inlet temperature and heat flux applied were 30 ℃ and 147 kW/m2 and only for the 0.635 mm channel. The friction factors obtained for the widest channel （Dh = 0.635 mm） are reported for both adiabatic and non-adiabatic experiments to assess possible temperature effects. The paper focuses on the effect of hydraulic diameter on pressure drop and friction factor over the experimental conditions. The pressure drop was found to decrease as the inlet temperature was increased, while the friction factors for the three test sections did not show significant differences. The experimental friction factors were in reasonable agreement with conventional developing flow theory. The effect of temperature on friction factor was not considerable as the friction factor with and without heat flux was almost the same.
文摘C. taylorii （Chrysophaeum taylorii） Lewis and Bryan （Pelagophyceae） are benthic mucilage-producing microalgae recently recorded in the Mediterranean Sea, where its summer blooms are having detrimental effects on benthic communities, fisheries and tourism, especially along the Sardinian coasts （western Mediterranean Sea）. Although few informations on the bloom dynamics of this microalga are available in literature jet, recent studies have hypothesized that sea water temperature plays a major role in determining the distribution and abundance of C. taylorii. The goal of this pilot study was to verify the above-mentioned statement providing experimental evidence for it. To this purpose, C. taylorii presence and abundance were investigated along a temperature gradient near the powerhouse of Torre Valdaliga （Latium coasts）, where a stream of hot water is continuously pumped out from the powerhouse into the sea. The obtained data showed that C. taylorii abundance was significantly higher in the study sites nearer to the powerhouse and a positive correlation between water temperature and cell densities was found, thus confirming that water temperature is one of the environmental variables directly influencing the bloom dynamics of this microalga in the Mediterranean Sea.
文摘In order to fulfil the microgravity requirements for space experiments, improved technology for the microgravity environment is proposed, including that for raising the orbital altitude, optimizing the layout of the disturbance source, using IN-thrusters instead of 5 N-thrusters, etc. In addition, evaluation of the microgravity environment of the recoverable satellite was also conducted using on-orbit micro-vibration measurement, on-orbit experiment and data analysis technologies. The microgravity level of the SJ-l0 recoverable satellite in China is compared with the spacecraft used for carrying out space science experiments internationally. This paper describes the microgravity environment of the SJ- 10 recoverable satellite, and its importance for analysing space experimental results.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50805130, 50775206)the Zhejiang Nature Science Foundation of China (Grant Nos. Y1090620, R1090833)+1 种基金the Tribology Science Fund of State Key Laboratory of Tribology of China (Grant No. SKLTKF08B01)the Program of Young Leaders and Core Instructors of Disciplines in Science of Zhejiang University of Technology (Grant No. 102004829)
文摘The orientation of the dimple increases the flow distance in the dimple and produces fluid cumulative effect in the dimple length direction, which leads to obvious hydrodynamic effect as a result. In order to investigate the hydrodynamic effect of orientation dimples, a series of experiments was carried out on a ring-on-ring test. Multi-pored faces were tested with different dimple inclination angles and slender ratios. Film thickness and frictional torque were measured under different conditions of load and rotation speed. Experimental results showed that the orientation dimple could produce obvious dynamic effect by change of the flow direction and the increasing dimple orientation leads to increase of the load capability. The hydrodynamic effect strongly depends on dimple orientation parameters such as inclination angle and slender ratio. A larger load capability can be available by increasing dimple orientation and rotation speed. Experimental results agreed well with the theory that orientation micro-pores can significantly improve hydrodynamic performance of surfaces.
基金supported in part by the Ministry of Science and Technology of China (Gramt No. 2006CB808100)supported by the National Natural Science Foundation of China(Grant No. 11005117)
文摘The aim of the Daya Bay reactor antineutrino experiment is to determine the neutrino mixing angle 813 with a sensitivity of 0.01 or better at 90% confidence level. In order to improve the position resolution of both the positron interaction and the neu- tron capture, the inside of the antineutrino detectors should be as unreflecting as possible. A black matt fluorocarbon paint is coated on the inner surface of the detectors made of 304L stainless steel to meet the physical requirement. This paint is com- patible with mineral oil, has low radioactivity, is easy to spray and fast curing at normal temperatures. The coating has excel- lent performance such as good adhesive force, uniformity, compact, scratch and wear resistance, and so on. It is the first appli- cation of such paint to large physical devices.
