Based on microscope and image processing, a new method of auto tool setting for micro milling was presented. Firstly, a realtime image of tool setting area was obtained by microscope and CCD camera, then image process...Based on microscope and image processing, a new method of auto tool setting for micro milling was presented. Firstly, a realtime image of tool setting area was obtained by microscope and CCD camera, then image processing was carried out on this image and the gap between the tool and workpiece was calculated. The gap measurement was sent to motion controlling card to make the tool approach to the surface of workpiece. These steps were repeated until the gap is zero, which means that tool setting was finished. Moreover, a reliability verification test was conducted. Results indicated that the precision of tool setting is satisfactory.展开更多
We made an experimental study and analysis on the relationships between filtration collecting efficiency and porosity, fiber diameter, and particles diameters for differential porosity media when fibrous media collect...We made an experimental study and analysis on the relationships between filtration collecting efficiency and porosity, fiber diameter, and particles diameters for differential porosity media when fibrous media collecting lube-oil. The influencing extent of porosity, dust concentration, and velocity impacting on collecting efficiency were researched by orthogonal experimental test. The results showed that porosity had the best salience affection on collecting efficiency, and the affection of velocity and dust concentration was less. The main factors of impacting on collecting efficiency were porosity, fiber diameter, particles diameter, dust concentration, filtration time and filtration velocity. The correlation formula between collecting efficiency and porosity, aperture diameter, fiber diameter, particles diameter, the thickness of media, and filtration time was obtained. It can forecast the collecting efficiency of lube-oil filtration media and provide a guide for selecting suitable fibrous filtration media.展开更多
Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the...Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.展开更多
The aim of presented study was to determine the behavioural response of precopulatory pairs of Gammarus tigrinus exposed to the 17α-ethinylestradiol （EE2）. It was hypothesized that 17α-ethinylestradiol would incre...The aim of presented study was to determine the behavioural response of precopulatory pairs of Gammarus tigrinus exposed to the 17α-ethinylestradiol （EE2）. It was hypothesized that 17α-ethinylestradiol would increase the time needed for a male to re-capture a female. Hypothesis was tested in a laboratory with 20 precopula pairs exposed to different treatment conditions. Paired animals were exposed to two different compound concentrations of 50 ng·L-1 and 500 ng·L-1. The control and solvent control was artificial sea water and artificial sea water with ethanol （the diluent for EE2）. The couples were tested several times under different experimental treatments. The obtained results indicate that EE2 affects the precopulatory mate guarding behaviour of Gammarus tigrinus. EE2 in concentration of 50 ng·L-1 and 500 ng·L-1 prolonged the time needed for re-pairing. However, relative to the controls only EE2 in concentration of 500 ng·L-1 significantly prolonged the time needed for male-female re-coupling. In summary, EE2 affects the reproductive behaviour of Gammarus tigrinus.展开更多
Recently, a lightning surge is recognized as one of the biggest risks to the society. If the surges induced by lightning invade into low voltage distribution lines, there might be a possibility of giving some severe d...Recently, a lightning surge is recognized as one of the biggest risks to the society. If the surges induced by lightning invade into low voltage distribution lines, there might be a possibility of giving some severe damages to the systems. Therefore, it is necessary to examine these induced phenomena. FDTD （finite difference time domain） method which treats objects as three-dimensional solid circuits is applied to analyze these induced phenomena. VSTL （Virtual Surge Test Lab.） is the surge analysis simulation program using FDTD method. In this paper, the lightning induced phenomena on the low voltage distribution line in the house are analyzed by using VSTL. In this paper, investigation results about induced surge when a lightning struck the point nearby the house, and about a suppressing effect of surges by comparing the results of analysis with and without SPD （surge protective device） are shown. As a result, it is confirmed that SPD is effective for suppressing lightning surge.展开更多
The hypersonic flow at orbital speeds is a fundamental issue for the ground tests of aerospace crafts.The detonation-driven high-enthalpy expansion tube(JF16 expansion tube)was developed to investigate re-entry physic...The hypersonic flow at orbital speeds is a fundamental issue for the ground tests of aerospace crafts.The detonation-driven high-enthalpy expansion tube(JF16 expansion tube)was developed to investigate re-entry physics.A forward detonation cavity(FDC)driver was applied in the JF16 expansion tube to create stable driving flows.The sound speed ratio of the detonated to test gas was examined to minimize the magnitude of test flow perturbations.The acceleration section length,incident shock decay and diaphragms thickness were investigated in detail to obtain optimal operation parameters.Flow visualization was also carried out with schlieren system to demonstrate the test flow stability and the effective test duration.Experimental data showed that the test flow with a velocity of 8.3 km/s and a total enthalpy up to 40 MJ/kg can be generated successfully and the test duration lasts for more than 50μs.展开更多
基金Supported by National Natural Science Foundation of China (No. 50935003)
文摘Based on microscope and image processing, a new method of auto tool setting for micro milling was presented. Firstly, a realtime image of tool setting area was obtained by microscope and CCD camera, then image processing was carried out on this image and the gap between the tool and workpiece was calculated. The gap measurement was sent to motion controlling card to make the tool approach to the surface of workpiece. These steps were repeated until the gap is zero, which means that tool setting was finished. Moreover, a reliability verification test was conducted. Results indicated that the precision of tool setting is satisfactory.
基金Shanghai Leading Academic Discipline Project,China(No.B604)
文摘We made an experimental study and analysis on the relationships between filtration collecting efficiency and porosity, fiber diameter, and particles diameters for differential porosity media when fibrous media collecting lube-oil. The influencing extent of porosity, dust concentration, and velocity impacting on collecting efficiency were researched by orthogonal experimental test. The results showed that porosity had the best salience affection on collecting efficiency, and the affection of velocity and dust concentration was less. The main factors of impacting on collecting efficiency were porosity, fiber diameter, particles diameter, dust concentration, filtration time and filtration velocity. The correlation formula between collecting efficiency and porosity, aperture diameter, fiber diameter, particles diameter, the thickness of media, and filtration time was obtained. It can forecast the collecting efficiency of lube-oil filtration media and provide a guide for selecting suitable fibrous filtration media.
文摘Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.
文摘The aim of presented study was to determine the behavioural response of precopulatory pairs of Gammarus tigrinus exposed to the 17α-ethinylestradiol （EE2）. It was hypothesized that 17α-ethinylestradiol would increase the time needed for a male to re-capture a female. Hypothesis was tested in a laboratory with 20 precopula pairs exposed to different treatment conditions. Paired animals were exposed to two different compound concentrations of 50 ng·L-1 and 500 ng·L-1. The control and solvent control was artificial sea water and artificial sea water with ethanol （the diluent for EE2）. The couples were tested several times under different experimental treatments. The obtained results indicate that EE2 affects the precopulatory mate guarding behaviour of Gammarus tigrinus. EE2 in concentration of 50 ng·L-1 and 500 ng·L-1 prolonged the time needed for re-pairing. However, relative to the controls only EE2 in concentration of 500 ng·L-1 significantly prolonged the time needed for male-female re-coupling. In summary, EE2 affects the reproductive behaviour of Gammarus tigrinus.
文摘Recently, a lightning surge is recognized as one of the biggest risks to the society. If the surges induced by lightning invade into low voltage distribution lines, there might be a possibility of giving some severe damages to the systems. Therefore, it is necessary to examine these induced phenomena. FDTD （finite difference time domain） method which treats objects as three-dimensional solid circuits is applied to analyze these induced phenomena. VSTL （Virtual Surge Test Lab.） is the surge analysis simulation program using FDTD method. In this paper, the lightning induced phenomena on the low voltage distribution line in the house are analyzed by using VSTL. In this paper, investigation results about induced surge when a lightning struck the point nearby the house, and about a suppressing effect of surges by comparing the results of analysis with and without SPD （surge protective device） are shown. As a result, it is confirmed that SPD is effective for suppressing lightning surge.
基金The National Natural Science Foundation of China (Grant Nos. 10632090 and 10621202)
文摘The hypersonic flow at orbital speeds is a fundamental issue for the ground tests of aerospace crafts.The detonation-driven high-enthalpy expansion tube(JF16 expansion tube)was developed to investigate re-entry physics.A forward detonation cavity(FDC)driver was applied in the JF16 expansion tube to create stable driving flows.The sound speed ratio of the detonated to test gas was examined to minimize the magnitude of test flow perturbations.The acceleration section length,incident shock decay and diaphragms thickness were investigated in detail to obtain optimal operation parameters.Flow visualization was also carried out with schlieren system to demonstrate the test flow stability and the effective test duration.Experimental data showed that the test flow with a velocity of 8.3 km/s and a total enthalpy up to 40 MJ/kg can be generated successfully and the test duration lasts for more than 50μs.
