Experimentally, the electron drag effect on carbon nanotube surface in flowing liquids was investigated. It was found that electric current could be generated in metallic carbon nanotubes immersed in the liquids. Carb...Experimentally, the electron drag effect on carbon nanotube surface in flowing liquids was investigated. It was found that electric current could be generated in metallic carbon nanotubes immersed in the liquids. Carbon nanotubes were synthesized on Si substrate by hot filament chemical vapor deposition. The experimental results showed that the flow-induced current on the surface of carbon nanotube films was closely depended on the flow rate, concentration, properties and temperature of liquids. The flow-induced current was increased with the increasing of flow rate, concentration and temperature of liquids. The obtained results were discussed in detail.展开更多
This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and ...This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters. Then, the response of PWCP for the oil-water stratified flow is calculated, and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness, and is almost independant of the angle between the oil-water interface and the sensor electrode. Finally, the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.展开更多
A special device was designed to measure temperature difference in this study of heat transfer of water and oil cross flow inside vertical upward tubes. A new heat transfer correlation was obtained for cross flow. The...A special device was designed to measure temperature difference in this study of heat transfer of water and oil cross flow inside vertical upward tubes. A new heat transfer correlation was obtained for cross flow. The experimental results showed that the dependence of heat transfer on Reynolds is much smaller in a narrow space than that in a wide space. It was found that the heat transfer correlation of cross flow in a narrow space is obviously different from that in a wide space, and that the heat transfer correlation obtained in a wide space may not be applicable to the cross-flow heat transfer in a narrow space. Further, the single-phase heat transfer capability of water cross flow was compared with that of oil cross flow. The experimental results showed that the average heat transfer coefficient of water is about 2～3 times that ofoil when they have the same superficial velocity.展开更多
Based on flow loss, a new automatic pipe-routing algorithm is proposed for electromechanical product in 3D space, which consists of pre-processing and optimization search. Utilizing chaos theory, a chaos grid preproce...Based on flow loss, a new automatic pipe-routing algorithm is proposed for electromechanical product in 3D space, which consists of pre-processing and optimization search. Utilizing chaos theory, a chaos grid preprocessing model （CGPM） is established to efficiently pick up the solution space and reduce the search range in the pre-processing, which simplifies the optimization search. A modified particle swarm optimization （PSO） algorithm is presented to seek for an approximate optimal trajectory in the solution space in the optimization search based on standard PSO algorithm and migration characters of people. The comparison of experiments and analysis results shows that the modified PSO algorithm is capable of preventing prematurity effectively and searching for the optimal trajectory more efficiently. Theoretical analysis proves that the modified PSO algorithm converges at global optimum. The examples show that the automatic pipe-routing algorithm based on flow loss is effective and practical for eleetromechanieal product.展开更多
In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature ...In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature of BD （bypass diodes） mounted on PV modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BDs. Measuring BD temperatures is easier than other conventional methods of fault detection. From the results of the rise in BD temperature under dark conditions, the increase in temperature increased linearly with increasing current flow. There is a proportional relationship between heat generated and the increasing temperature of the terminal box. The experimental results about surface temperature of the junction box in actual system operation suggested that the electric current through a BD in a terminal box can be known by measuring the surface temperature of the terminal box for PV module fault detection without a system shutdown. Moreover, we tried to evaluate temperature distribution of a terminal box using heat conduction equations. The evaluated results agreed well with the measured results.展开更多
Objective:To investigate the relationship between the temperature and the microvascular blood flow of the cerebral cortex, and the influence of electro-acupuncture (EA) on the cortical microcirculation. Methods: High ...Objective:To investigate the relationship between the temperature and the microvascular blood flow of the cerebral cortex, and the influence of electro-acupuncture (EA) on the cortical microcirculation. Methods: High temperature spots on the anterior ectosylvian and low temperature spots on the posterior suprasylvian on the cortical surface of 20 cats were identified using cortical infrared thermography (CIT); the blood flow in the microcirculation on these spots was measured with laser-Doppler flowmetry. EA was given at Zusanli (ST 36) and changes in the blood flow in the cerebral cortex microcirculation were detected. Results: 1) The mean temperatures on the high (34.83±0.24°C) and low (32.28±0.27°C) temperature spots were significantly different (P<0.001); this was indicative of a temperature difference on the cortical surface; 2) The average blood flow in the microcirculation of the high (266.8±19.2 PU) and low (140.8±9.9 PU) temperature spots was significantly different (P<0.001). 3) On the cortical high temperature spots, the mean blood flow in the microcirculation significantly increased from 266.8±86.8 PU before EA, to 422.5±47.4 PU following 5 minutes of EA (58.35%; P<0.01), and 431.8±52.8 PU 5 minutes after ceasing EA (61.84%; P<0.01). 4) On the low temperature spots, there were no significant differences in blood flow following 5 minutes of EA (146.3±11.5 PU), and 5 minutes after ceasing EA (140.5±11.6 PU), when compared with that before acupuncture (140.8±9.9 PU; P>0.9). Conclusion: The high temperature spots of the cortex are active functional regions of neurons with higher blood flow and a stronger response to EA. EA induces a significant increase in blood flow in the high temperature spots of the cortex.展开更多
The single-walled carbon nanotube （SWCNT） is a promising nanostructure in the design of future high- frequency system-on-chip, especially in network-on-chip, where the quality of communication between intellectual p...The single-walled carbon nanotube （SWCNT） is a promising nanostructure in the design of future high- frequency system-on-chip, especially in network-on-chip, where the quality of communication between intellectual property （IP） modules is a major concern. Shrinking dimensions of circuits and systems have restricted the use of high-frequency signal characteristics for frequencies up to 1000 GHz. Four key electrical parameters, impedance, propagation constant, current density, and signal delay time, which are crucial in the design of a high-quality interconnect, are derived for different structural configurations of SWCNT. Each of these parameters exhibits strong dependence on the frequency range over which the interconnect is designed to operate, as well as on the configuration of SWCNT. The novelty of the proposed model for solving next-generation high-speed integrated circuit （IC） interconnect challenges is illustrated, compared with existing theoretical and experimental results in the literature.展开更多
We present an ultrasensitive ultraviolet （UV） detector based on a p-type ZnS nanoribbon （NR）/indium tin oxide （ITO） Schottky barrier diode （SBD）. The device exhibits a pseudo-photovoltaic behavior which can al...We present an ultrasensitive ultraviolet （UV） detector based on a p-type ZnS nanoribbon （NR）/indium tin oxide （ITO） Schottky barrier diode （SBD）. The device exhibits a pseudo-photovoltaic behavior which can allow the SBD to detect UV light irradiation with incident power of 6 × 10^-17 W （-85 photons/s on the NR） at room temperature, with excellent reproducibility and stability. The corresponding detectivity and photoconductive gain are calculated to be 3.1 × 10^20 cm.Hz1/2.W^-1 and 6.6 × 10^5, respectively. It is found that the presence of the trapping states at the p-ZnS NWITO interface plays a crucial role in determining the ultrahigh sensitivity of this nanoSBDs. Based on our theoretical calculation, even ultra-low photon fluxes on the order of several tens of photons could induce a significant change in interface potential and consequently cause a large photocurrent variation. The present study provides new opportunities for developiphigh-performance optoelectronic devices in the future.展开更多
文摘Experimentally, the electron drag effect on carbon nanotube surface in flowing liquids was investigated. It was found that electric current could be generated in metallic carbon nanotubes immersed in the liquids. Carbon nanotubes were synthesized on Si substrate by hot filament chemical vapor deposition. The experimental results showed that the flow-induced current on the surface of carbon nanotube films was closely depended on the flow rate, concentration, properties and temperature of liquids. The flow-induced current was increased with the increasing of flow rate, concentration and temperature of liquids. The obtained results were discussed in detail.
基金Supported by the National Natural Science Foundation of China （50974095, 41174109, 61104148）, and the National Science and Technology Mai or Projects （2011ZX05020-006）.
文摘This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters. Then, the response of PWCP for the oil-water stratified flow is calculated, and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness, and is almost independant of the angle between the oil-water interface and the sensor electrode. Finally, the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.
文摘A special device was designed to measure temperature difference in this study of heat transfer of water and oil cross flow inside vertical upward tubes. A new heat transfer correlation was obtained for cross flow. The experimental results showed that the dependence of heat transfer on Reynolds is much smaller in a narrow space than that in a wide space. It was found that the heat transfer correlation of cross flow in a narrow space is obviously different from that in a wide space, and that the heat transfer correlation obtained in a wide space may not be applicable to the cross-flow heat transfer in a narrow space. Further, the single-phase heat transfer capability of water cross flow was compared with that of oil cross flow. The experimental results showed that the average heat transfer coefficient of water is about 2～3 times that ofoil when they have the same superficial velocity.
文摘Based on flow loss, a new automatic pipe-routing algorithm is proposed for electromechanical product in 3D space, which consists of pre-processing and optimization search. Utilizing chaos theory, a chaos grid preprocessing model （CGPM） is established to efficiently pick up the solution space and reduce the search range in the pre-processing, which simplifies the optimization search. A modified particle swarm optimization （PSO） algorithm is presented to seek for an approximate optimal trajectory in the solution space in the optimization search based on standard PSO algorithm and migration characters of people. The comparison of experiments and analysis results shows that the modified PSO algorithm is capable of preventing prematurity effectively and searching for the optimal trajectory more efficiently. Theoretical analysis proves that the modified PSO algorithm converges at global optimum. The examples show that the automatic pipe-routing algorithm based on flow loss is effective and practical for eleetromechanieal product.
文摘In recent years, PV （photovoltaic） systems have been installed rapidly around the world. However, there is often a delay in the practical application of fault detection in PV systems. In this study, the temperature of BD （bypass diodes） mounted on PV modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BDs. Measuring BD temperatures is easier than other conventional methods of fault detection. From the results of the rise in BD temperature under dark conditions, the increase in temperature increased linearly with increasing current flow. There is a proportional relationship between heat generated and the increasing temperature of the terminal box. The experimental results about surface temperature of the junction box in actual system operation suggested that the electric current through a BD in a terminal box can be known by measuring the surface temperature of the terminal box for PV module fault detection without a system shutdown. Moreover, we tried to evaluate temperature distribution of a terminal box using heat conduction equations. The evaluated results agreed well with the measured results.
基金supported by a grant from the National Natural Science Fund of China (No. 39770925)Science Research Fund of The Ministry of Personnel for Excellent Returnees (1998)Beijing Key Laboratory Fund of The Science and Technology Commission of Beijing (951890600)
文摘Objective:To investigate the relationship between the temperature and the microvascular blood flow of the cerebral cortex, and the influence of electro-acupuncture (EA) on the cortical microcirculation. Methods: High temperature spots on the anterior ectosylvian and low temperature spots on the posterior suprasylvian on the cortical surface of 20 cats were identified using cortical infrared thermography (CIT); the blood flow in the microcirculation on these spots was measured with laser-Doppler flowmetry. EA was given at Zusanli (ST 36) and changes in the blood flow in the cerebral cortex microcirculation were detected. Results: 1) The mean temperatures on the high (34.83±0.24°C) and low (32.28±0.27°C) temperature spots were significantly different (P<0.001); this was indicative of a temperature difference on the cortical surface; 2) The average blood flow in the microcirculation of the high (266.8±19.2 PU) and low (140.8±9.9 PU) temperature spots was significantly different (P<0.001). 3) On the cortical high temperature spots, the mean blood flow in the microcirculation significantly increased from 266.8±86.8 PU before EA, to 422.5±47.4 PU following 5 minutes of EA (58.35%; P<0.01), and 431.8±52.8 PU 5 minutes after ceasing EA (61.84%; P<0.01). 4) On the low temperature spots, there were no significant differences in blood flow following 5 minutes of EA (146.3±11.5 PU), and 5 minutes after ceasing EA (140.5±11.6 PU), when compared with that before acupuncture (140.8±9.9 PU; P>0.9). Conclusion: The high temperature spots of the cortex are active functional regions of neurons with higher blood flow and a stronger response to EA. EA induces a significant increase in blood flow in the high temperature spots of the cortex.
文摘The single-walled carbon nanotube （SWCNT） is a promising nanostructure in the design of future high- frequency system-on-chip, especially in network-on-chip, where the quality of communication between intellectual property （IP） modules is a major concern. Shrinking dimensions of circuits and systems have restricted the use of high-frequency signal characteristics for frequencies up to 1000 GHz. Four key electrical parameters, impedance, propagation constant, current density, and signal delay time, which are crucial in the design of a high-quality interconnect, are derived for different structural configurations of SWCNT. Each of these parameters exhibits strong dependence on the frequency range over which the interconnect is designed to operate, as well as on the configuration of SWCNT. The novelty of the proposed model for solving next-generation high-speed integrated circuit （IC） interconnect challenges is illustrated, compared with existing theoretical and experimental results in the literature.
文摘We present an ultrasensitive ultraviolet （UV） detector based on a p-type ZnS nanoribbon （NR）/indium tin oxide （ITO） Schottky barrier diode （SBD）. The device exhibits a pseudo-photovoltaic behavior which can allow the SBD to detect UV light irradiation with incident power of 6 × 10^-17 W （-85 photons/s on the NR） at room temperature, with excellent reproducibility and stability. The corresponding detectivity and photoconductive gain are calculated to be 3.1 × 10^20 cm.Hz1/2.W^-1 and 6.6 × 10^5, respectively. It is found that the presence of the trapping states at the p-ZnS NWITO interface plays a crucial role in determining the ultrahigh sensitivity of this nanoSBDs. Based on our theoretical calculation, even ultra-low photon fluxes on the order of several tens of photons could induce a significant change in interface potential and consequently cause a large photocurrent variation. The present study provides new opportunities for developiphigh-performance optoelectronic devices in the future.
