In order to enhance the ultrasonic degradation rate of organic solutions,a metal plate is placed at the water–air interface of the ultrasonic cleaning tank.Initially,the distribution of the acoustic field in the ultr...In order to enhance the ultrasonic degradation rate of organic solutions,a metal plate is placed at the water–air interface of the ultrasonic cleaning tank.Initially,the distribution of the acoustic field in the ultrasonic water tank was calculated using the simulation software COMSOL.The simulation results demonstrated that the utilization of the metal plate can eliminate the standing-wave acoustic field to a certain extent.Subsequently,the pixel method was selected for a quantitative comparison of the cavitation area in the flume with and without the metal plate.The results demonstrated that,under specific conditions,the area of ultrasonic cavitation in the water tank can be expanded using a metal plate.Thereafter,an acoustic degradation experiment was designed to confirm the feasibility of the simulation method.Furthermore,the impacts of the amplitude of the incident ultrasonic pressure,frequency,and the height of the liquid level in the water tank on the cavitation area were investigated.展开更多
Flange height and lip accuracy are generally restricted by the formability of sheet metals in the conventional hole-flanging operation. A new hole-flanging process, named upsetting-flanging process, was proposed to ob...Flange height and lip accuracy are generally restricted by the formability of sheet metals in the conventional hole-flanging operation. A new hole-flanging process, named upsetting-flanging process, was proposed to obtain a more substantial flange from thick plate. The finite element method （FEM） with DEFORM was utilized to simulate the novel upsetting-flanging process and the influence of geometric parameters on the flange height was studied in details. A series of flanging experiments with A1050P-O were carried out to validate the FEM results, and the variations of Vicker hardness in the plate section were discussed. The results showed that the newly upsetting-flanging process revealed higher flange height and better lip accuracy than the conventional hole-flanging process, and the results between FEM simulations and experiments showed good agreement. Besides, the hardness of the plate around the flange part increases due to the work hardening after the upsetting-flanging process, which reveals better superiority in strength for the subsequent machining or assembling processes.展开更多
Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste ...Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.展开更多
Coal wall stability is a critical factor influencing coal mining efficiency and threatens the safety of working faces,where irregular coal wall surfaces significantly affect the contact and support effectiveness of th...Coal wall stability is a critical factor influencing coal mining efficiency and threatens the safety of working faces,where irregular coal wall surfaces significantly affect the contact and support effectiveness of the support plate,thereby impacting stability.Through a combination of theoretical analysis,mechanical testing,and numerical simulations,this study establishes a mechanical model of irregular coal wall surfaces to investigate the effects of the undulation period and undulation height on coal wall failure characteristics.This research reveals the mechanical response mechanisms of irregular coal wall surfaces and proposes an innovative method to enhance coal wall stability by improving the supporting cushion material of the support plate,which was validated through numerical simulations.The results show that the undulation height and undulation period significantly influence the macroscopic mechanical parameters of the samples,with the undulation height exerting a more pronounced effect.The strength of the samples with undulating surfaces is approximately 50%-60% that of the samples with flat surfaces.The failure mode under uniaxial compression is predominantly tensile,resulting in long and slender block fragments with a characteristic“Ⅲ”-shaped tensile fracture pattern.During the loading process,samples with undu-lating surfaces dissipate energy at all stages,with a greater proportion of energy dissipation occurring during the early loading stage because of structural damage and the formation of internal cracks.The surface compressive and tensile stresses are correlated with the curvature radius of the convex surface and the elastic modulus of the supporting plate.Reducing the elastic modulus of the supporting plate material can effectively alleviate the stress concentration at convex locations and increase the peak strength.This study provides theoretical foundations and technical references for the prevention and control of coal wall spalling in deep thick coal seam mining.展开更多
基金supported by the Doctoral Fund Program of Longdong University(Grant No.XYBYZK2219)the National Natural Science Foundation of China(Grant No.12274277)+1 种基金the Science and Technology Project of Gansu Province of China(Grant No.21JR11RM046)Young Doctor Fund of Gansu Education Department(Grant No.2022QB-171).
文摘In order to enhance the ultrasonic degradation rate of organic solutions,a metal plate is placed at the water–air interface of the ultrasonic cleaning tank.Initially,the distribution of the acoustic field in the ultrasonic water tank was calculated using the simulation software COMSOL.The simulation results demonstrated that the utilization of the metal plate can eliminate the standing-wave acoustic field to a certain extent.Subsequently,the pixel method was selected for a quantitative comparison of the cavitation area in the flume with and without the metal plate.The results demonstrated that,under specific conditions,the area of ultrasonic cavitation in the water tank can be expanded using a metal plate.Thereafter,an acoustic degradation experiment was designed to confirm the feasibility of the simulation method.Furthermore,the impacts of the amplitude of the incident ultrasonic pressure,frequency,and the height of the liquid level in the water tank on the cavitation area were investigated.
基金Project(51175445)supported by the National Natural Science Foundation of ChinaProject(2010DFA52130)supported by the International Cooperation Project of the Ministry of Science and Technology,ChinaProject(CX2013B277)supported by Hunan Provincial Innovation Foundation for Postgraduate,China
文摘Flange height and lip accuracy are generally restricted by the formability of sheet metals in the conventional hole-flanging operation. A new hole-flanging process, named upsetting-flanging process, was proposed to obtain a more substantial flange from thick plate. The finite element method （FEM） with DEFORM was utilized to simulate the novel upsetting-flanging process and the influence of geometric parameters on the flange height was studied in details. A series of flanging experiments with A1050P-O were carried out to validate the FEM results, and the variations of Vicker hardness in the plate section were discussed. The results showed that the newly upsetting-flanging process revealed higher flange height and better lip accuracy than the conventional hole-flanging process, and the results between FEM simulations and experiments showed good agreement. Besides, the hardness of the plate around the flange part increases due to the work hardening after the upsetting-flanging process, which reveals better superiority in strength for the subsequent machining or assembling processes.
文摘Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.
基金the National Key Research and Development Program of China(Nos.2023YFC2907501 and 2023YFC2907503)the National Natural Science Foundation of China(Nos.52374106 and 52274154)the Fundamental Research Funds for the Central Universities(No.2023YQTD02).
文摘Coal wall stability is a critical factor influencing coal mining efficiency and threatens the safety of working faces,where irregular coal wall surfaces significantly affect the contact and support effectiveness of the support plate,thereby impacting stability.Through a combination of theoretical analysis,mechanical testing,and numerical simulations,this study establishes a mechanical model of irregular coal wall surfaces to investigate the effects of the undulation period and undulation height on coal wall failure characteristics.This research reveals the mechanical response mechanisms of irregular coal wall surfaces and proposes an innovative method to enhance coal wall stability by improving the supporting cushion material of the support plate,which was validated through numerical simulations.The results show that the undulation height and undulation period significantly influence the macroscopic mechanical parameters of the samples,with the undulation height exerting a more pronounced effect.The strength of the samples with undulating surfaces is approximately 50%-60% that of the samples with flat surfaces.The failure mode under uniaxial compression is predominantly tensile,resulting in long and slender block fragments with a characteristic“Ⅲ”-shaped tensile fracture pattern.During the loading process,samples with undu-lating surfaces dissipate energy at all stages,with a greater proportion of energy dissipation occurring during the early loading stage because of structural damage and the formation of internal cracks.The surface compressive and tensile stresses are correlated with the curvature radius of the convex surface and the elastic modulus of the supporting plate.Reducing the elastic modulus of the supporting plate material can effectively alleviate the stress concentration at convex locations and increase the peak strength.This study provides theoretical foundations and technical references for the prevention and control of coal wall spalling in deep thick coal seam mining.
