571 research outputs found
Growth Response of Spathiphyllum ‘Sensation’ and Dracaena sanderiana ‘Celica’ to Iron Concentration
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Effect of HCl in NaCl solution in the determination of exchange acidity and its simulation by MINEQL. 1996.
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Effects of Personal Exposure to Particulate Matter and Ozone on Arterial Stiffness and Heart Rate Variability in Healthy Adults
No full textStudies on friction stir lap welding of Cu-Ni alloy and low carbon steel
No full textIn this study, the experimental apparatus with a friction stir welding dynamometer was employed to investigate the joint characteristics of Cu-Ni alloy plate in thickness of 3.6mm lap-welding to low carbon steel plate in thickness of 4 mm using cylinder type tool (without probe) under the welding parameters of rotating speeds (800~1400 rpm) and traveling speed of tool (10~80 mm/min). To prevent the joint interface from oxidizing during the welding process, the joint interfaces of Cu-Ni alloy and low carbon steel respectively were electroplated with Ni coating layer in different thicknesses before the welding. The effect of the thickness of Ni coating layer on shear strength of joint interface and the mechanism of welding are also investigated.
Experimental results show that under the rotating speed of 1000 rpm and travelling speed of 10 mm/min, the shear strength for without Ni coating layer is measured about 100 MPa. On the other hand, the shear strength is increased to saturated value of 290 MPa with increasing the thickness of Ni coating layer. Especially, the shear strength of joint interface for the Cu-Ni alloy with 5\uce\ubcm thickness of Ni coating layer lap-welding to low carbon steel with thickness of 20\uce\ubcm thickness of Ni coating layer is about 2.9 times of that for without Ni coating layer. Moreover, the downward force (Fd) is decreased and the maximum interface temperature (Tmax) and shear strength (\ucf) are increased with increasing the rotating speed (N). The downward force is increased and the maximum interface temperature and shear strength are decreased with increasing the traveling speed (f). This complex relationship is discussed by the new parameter of Fd\ue2\ua2N/f, the relationship among Fd\ue2\ua2N/f, maximum interface temperature and shear strength shows that the maximum interface temperature is increased and shear strength is increased to saturated value of 290 MPa with increasing Fd\ue2\ua2N/f. The phenomenon is explained that the diffusion bonding between the joint interface of two plates become more homogeneous
Studies on the performance improvement of an integrated apparatus for concentration of ferrous debris and viscosity of lubricant
No full textLubrication is the lifeblood of mechanical device during the operating conditions, so that the lubricating oil detection becomes one of an important modern technology. The operator can be as early as possible to know whether the abnormal wear occurs by detecting concentration of ferrous debris in the lubricating oil. Detecting the viscosity of lubricating oil can also allow the operator to monitor the deterioration degree of lubricating oil due to environmental factors, in order to ensure whether the lubricating oil losing its effectiveness. Our laboratory previously developed a prototype of integrated apparatus for detecting the concentration of ferrous debris and the viscosity of lubricant in a single process. This study focuses on improving this prototype, so that the apparatus possesses a LCD displayer and commercialization. The design of the integrated apparatus contains a sampling unit, a measurement unit of the ferrous debris concentration, a measurement unit of the viscosity, a data acquisition system, and LCD displayer panel.
In measurement unit of the ferrous debris concentration, Hall IC is used as a sensor to measure the concentration of ferrous debris by detecting the change of magnetic flux density between the magnetic poles due to the stacking of ferrous debris. In the measurement unit of the viscosity of the lubricating oils, the piston is used to squeeze the oil into the tank to measure the viscosity by detecting the load.
These two units are integrated into a measuring device, and there is no interference between the values measured by the Hall IC and the load cell. Finally, these two signals are fed to a personal computer for data analysis to obtain the concentration of ferrous debris and the viscosity of lubricant. Consequently, the operator can directly observe the measured results
Effect of shear rate on the Lubrication Characteristics of Oil in Water Emulsions
No full textIn this study, Reometer AR2000 is used to investigate the effect of shear rate on viscosity of emulsion. And a model for the effective viscosity of emulsion is established. Moreover, another model for the hydrodynamic lubrication with binary mixtures of non-Newton fluids is developed. The coupled modified Reynolds are solved by combining the advanced multilevel method with the Newton-Raphson method. The effect of shear rate on lubrication characteristics of hydrodynamic lubrication of emulsion is investigated in cold rolling process.
Research results show that the viscosity of emulsion is decreased with increasing the shear rate. Hence,the oil film thickness, oil preasure and oil concentration under hydrodynamic lubrication are increased with decreasing the slide-to roll ratio. Emulsion will be Newton fluid under high shear rate. In the cold rolling process, the emulsion shows the high shear rate, and the elastic deformation of roller and strip are considersd. Hence the end point of plastic zone of strip is moved to oulet zone due to the lubricated zone is increased, so that the film thickness is higher than that for rigid body. When roller radius is increased, the effective elastic modulus and the thickness reduction of strip are decreased, then the lubrication characteristics in cold rolling process are influenced by elastic deformation. When the rolling speed is increased , the inlet film thickness is increased, and the roll torque is slightly increased, but the rolling force and peak preasure are almost not influenced
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