Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of t...Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of the alloy were investigated. The results show that with the increase of the growth rate and the decrease of the diameter, the fullyβphase solidification changes to the peritectic solidification, and the final microstructure is composed of theα2/γlamellar structure and a multiphase microstructure （B2 phase,α2/γlamellar structure） respectively, which can be attributed to the solute enrichment resulting from the decreasing diffusion and convection ability. The occurrence of peritectic reaction at high growth rate promotes the solute segregation heavily and the coarse lamellar spacing in Al-and Nb-rich region, which greatly decreases the hardness values and leads to the discontinuity of the hardness curves with the increase of the growth rate. Comparatively, the Ti-46Al-8Nb alloy has lower hardness values than the other applied TiAl-based alloys in previous studies.展开更多
A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der dif...A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effec-tive diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.展开更多
In order to explore drum instability problems of thinning spinning ultra thin-walled tubes with large diameter-to-hickness ratio, experiments of thinning spinning ultra thin-walled tubes with different clearances betw...In order to explore drum instability problems of thinning spinning ultra thin-walled tubes with large diameter-to-hickness ratio, experiments of thinning spinning ultra thin-walled tubes with different clearances between the mandrel and the tube were carried out. The phenomena of drum instability were analyzed. Drum instability mechanism was studied. The important influence of the mandrel-locked ring on stable thinning spinning was found. Besides, two important parameters, namely drum ratio and drum stiffness, were proposed to characterize the drum instability of spinning ultra thin-walled tubes with large diameter-to-thickness ratio. What's more, numerical simulations were applied to explore the influences of different clearance ratios and diameter-to-thickness ratios on the drum instability. As a result, it is found that the mandrel-locked ring is the key to the stability and precision of spinning; drum ratio can reflect the degree of the deformation of the tubes; drum stiffness is a comprehensive index to measure the influences of the tube's own parameters on the spinning instability; both the clearance ratio and diameter-thickness ratio have significant influences on the drum ratio and drum stiffness.展开更多
For a graph G, let D denote an orientation of G having minimum diameter. Define f（G） =diamD. In this paper, we concentrate on exploring the minimum diameter of Km ∨ Kn（m ≥ 1, n ≥ 1）. Some special cases are know...For a graph G, let D denote an orientation of G having minimum diameter. Define f（G） =diamD. In this paper, we concentrate on exploring the minimum diameter of Km ∨ Kn（m ≥ 1, n ≥ 1）. Some special cases are known： f（Km ∨ Kn） = ∞, 2, 3, where m = landn ≥ 1, m = 2 or m ≥ 4 andn = 1, m=3 and n = 1, respectively. So we only consider the case when m ≥ 2 and n ≥ 2. The following results are obtained. （1） f（Km ∨ Kn） = 3, where m = 2, 3, n ≥ 2 and m = n = 4. （2） f（Km ∨ Kn） = 2, m where m ≥ 5 andmisodd, 2 ≤ n ≤ （m[m/2]）-m. （3） f（Km ∨ Kn） = 2, whereto ≥ 4 and m≡ 0（rood4）, 2 ≤ n ≤ （m m/2）-（m/2＋1）. （4） ]（Km ∨ Kn） = 2, where m ≥ 6 and m ≡ 2（mod4）, 2 ≤ n ≤ （m m/2）-m/2. （5）/（Km ∨ Kn） = 3, where m ≥ 4, n 〉 （m[m/2]）.展开更多
In order to explain the oscillation heat transfer dynamics of closed loop oscillation heat pipe (CLOHP) with two liquid slugs,analysis on the forces and heat transfer process of the partial gas-liquid phase system inv...In order to explain the oscillation heat transfer dynamics of closed loop oscillation heat pipe (CLOHP) with two liquid slugs,analysis on the forces and heat transfer process of the partial gas-liquid phase system involving multiple parameters was carried out,and a new type oscillation heat transfer dynamic model of the CLOHP was set up based on conservation laws of mass,momentum and energy.Application results indicate that its oscillation heat transfer dynamics features depend largely on the filling rate,pipe diameter and difference in temperature.Besides,oscillation intensity and transfer performance can be improved to a large extent by increasing the temperature difference properly and enlarging the pipe diameter within a certain range under a certain filling rate.展开更多
The properties and thickness of the bubbles in the froth control the flotation process. There is no work showing how to measure bubble film composition and thickness by a straightforward manner. In this work, a novel ...The properties and thickness of the bubbles in the froth control the flotation process. There is no work showing how to measure bubble film composition and thickness by a straightforward manner. In this work, a novel approach, a custom-designed bubble cell associated with layer interferometry(in the UV-vis region) and FT-IR spectroscopy was used to investigate the effect of solid particle type(hydrophilic vs hydrophobic), concentration and bubble diameter on stability of a bubble blown in air. Stability was quantified by measuring bubble lifetime and hydrated film thickness. Kerosene with silicone oil as a foaming agent was used to evaluate the impact of bubble diameter(test series I). Frother solutions(MIBC, Dowfroth 250, Hexanol and F-150) were used for the solid type concentration experiments(test series II). In the first series of experiments, it was determined that as the diameter of a bubble increased from 10 to 25 mm, so did the hydrated film thickness from 350 to 1000 nm. In the second series, as the silica concentration increased(0 to 10%), an increase in bubble lifetime and hydrated film thickness was resulted(130%-250%). An impact of solid hydrophobicity was found but to a lesser degree than expected. It is possible that the small particle size(<0.1 m) of silica was responsible for this behavior. The findings are used to interpret the effect of solids in flotation froth.展开更多
Essential oils are effective antimicrobials on important some pathogenic bacteria and can be added packaging materials due to absorb various surfaces. In this study, the aim is to determinate of antimicrobial effects ...Essential oils are effective antimicrobials on important some pathogenic bacteria and can be added packaging materials due to absorb various surfaces. In this study, the aim is to determinate of antimicrobial effects of methyl cellulose films with containing various proportions thyme, rosemary, coriander, basil and pimento berry oils （1%, 2%, 3% and 4% g/cc） against important bacteria as a surface contaminant Listeria innocua by in vitro. For this purpose, 1 cm diameter discs were cut from methyl cellulose films containing essential oils and inhibition zone diameter which were measured by the agar diffusion method. As the results of these analyses, all prepared active edible methyl cellulose films were antimicrobial effects on Listeria innocua. The most powerful antimicrobial effect achieved with methyl cellulose film including coriander oil on Listeria innocua. And also the weakest antimicrobial effect achieved with methyl cellulose film including rosemary oil on Listeria. All results were significant by statistically （p 〈 0.01） and all analyses were replicated in three times.展开更多
This paper presents an adaptive friction compensation method based on LuGre model for large diameter electric-hydraulic proportional valves in which the valve core contains friction.A mathematic model of the electric-...This paper presents an adaptive friction compensation method based on LuGre model for large diameter electric-hydraulic proportional valves in which the valve core contains friction.A mathematic model of the electric-hydraulic proportional valve is established,and the friction characteristics are described based on the LuGre model.The global asymptotic stability of the control system with the adaptive friction compensation controller is guaranteed over Lyapunov theorem.The adaptive compensation of the friction on LuGre friction model is verified by simulation and experiment.The steady-state error is about [-4.23 × 10^(-5)m,5.91 × 10^(-5)m]and[-2.5 × 10^(-4)m,2.6 ×10^(-4) m] on simulation and experiment,the position tracking accuracy is higher,and the lag time of the main valve through the dead zone is shorter.The result proves that the adaptive friction compensation method can effectively compensate for the negative effects of nonlinear friction.展开更多
Because pipeline has large pipe diameter, large throughout and high pressure, once pipeline leakage accident happens, the damage is quite serious. In addition, pipeline leakage accident caused by man-made drilling oil...Because pipeline has large pipe diameter, large throughout and high pressure, once pipeline leakage accident happens, the damage is quite serious. In addition, pipeline leakage accident caused by man-made drilling oil stolen every year results in huge economic losses on oilfield. Therefore, a real-time and accurate pipeline leak detection and location system not only can effectively decrease leakage loss and reduce the waste of manpower and material resources in patrolling work, but also is conductive to the management of oil pipeline and improvement of economic efficiency of enterprise. The paper determines leak detection and location project giving priority to negative pressure wave and supplemented by flow parameter analysis. The method not only can judge the accidence of leakage timely and accurately, but also can effectively avoid leakage false alarm caused by start or stop pumps in pipeline.展开更多
In this paper, we study the complete bounded λ-hypersurfaces in the weighted volume-preserving mean curvature flow. Firstly, we investigate the volume comparison theorem of complete bounded λ-hypersurfaces with |A|...In this paper, we study the complete bounded λ-hypersurfaces in the weighted volume-preserving mean curvature flow. Firstly, we investigate the volume comparison theorem of complete bounded λ-hypersurfaces with |A|≤α and get some applications of the volume comparison theorem. Secondly, we consider the relation among λ, extrinsic radius k, intrinsic diameter d, and dimension n of the complete λ-hypersurface,and we obtain some estimates for the intrinsic diameter and the extrinsic radius. At last, we get some topological properties of the bounded λ-hypersurface with some natural and general restrictions.展开更多
Immunomagnetic bead（IMB）-based enzyme-linked immunosorbent assay（ELISA） has been the tool frequently used for protein detection in research and clinical laboratories.For most ELISA reactions the recommended dosage...Immunomagnetic bead（IMB）-based enzyme-linked immunosorbent assay（ELISA） has been the tool frequently used for protein detection in research and clinical laboratories.For most ELISA reactions the recommended dosage of IMBs is usually according to their weight（mg） or mass fraction（w/v） instead of the bead number.Consequently, the processes occurring in the immediate vicinity of the IMBs have always been ignored by researchers and they cannot be revealed in detail during the ELISA reaction.In this paper, we established the relationship between number of IMBs and colorimetric results, and further proposed a new concept of ＂nominal effective immunoreaction volume（NEIV）＂ to characterize a single IMB during ELISA reaction.Results showed that the NEIV of a single IMB has a constant value, which is unrelated to the amount of beads and the concentration of antigen.Optimal results of the colorimetric ELISA are achieved when the incubation volume meets each IMB＇s NEIV and is no longer enhanced by increasing the incubation volume.Thus, the reliable and relatively precise number of IMBs for ELISA detection during practical application could be determined.Most importantly, a study using IMB＇s NEIV would lay the foundation for a kinetics analysis of IMBs and antigens for future study.展开更多
基金Projects(51071062,51274077,51271068)supported by the National Natural Science Foundation of ChinaProject(2011-P03)supported by Open Fund of State Key Laboratory of Mold and Die Technology of Huazhong University of Science and Technology+1 种基金Project(HIT.NSRIF.2013002)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2011CB605504)supported by the National Basic Research Program of China
文摘Bridgman-type directional solidification experiments were conducted for Ti-46Al-8Nb （mole fraction, %） alloy. The effects of the growth rate and the diameter on the microstructure, phase transition and hardness of the alloy were investigated. The results show that with the increase of the growth rate and the decrease of the diameter, the fullyβphase solidification changes to the peritectic solidification, and the final microstructure is composed of theα2/γlamellar structure and a multiphase microstructure （B2 phase,α2/γlamellar structure） respectively, which can be attributed to the solute enrichment resulting from the decreasing diffusion and convection ability. The occurrence of peritectic reaction at high growth rate promotes the solute segregation heavily and the coarse lamellar spacing in Al-and Nb-rich region, which greatly decreases the hardness values and leads to the discontinuity of the hardness curves with the increase of the growth rate. Comparatively, the Ti-46Al-8Nb alloy has lower hardness values than the other applied TiAl-based alloys in previous studies.
文摘A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effec-tive diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.
基金Project(2014CB046600)supported by the National Basic Research Program of China
文摘In order to explore drum instability problems of thinning spinning ultra thin-walled tubes with large diameter-to-hickness ratio, experiments of thinning spinning ultra thin-walled tubes with different clearances between the mandrel and the tube were carried out. The phenomena of drum instability were analyzed. Drum instability mechanism was studied. The important influence of the mandrel-locked ring on stable thinning spinning was found. Besides, two important parameters, namely drum ratio and drum stiffness, were proposed to characterize the drum instability of spinning ultra thin-walled tubes with large diameter-to-thickness ratio. What's more, numerical simulations were applied to explore the influences of different clearance ratios and diameter-to-thickness ratios on the drum instability. As a result, it is found that the mandrel-locked ring is the key to the stability and precision of spinning; drum ratio can reflect the degree of the deformation of the tubes; drum stiffness is a comprehensive index to measure the influences of the tube's own parameters on the spinning instability; both the clearance ratio and diameter-thickness ratio have significant influences on the drum ratio and drum stiffness.
基金the National Natural Science Foundation of China(10671095)
文摘For a graph G, let D denote an orientation of G having minimum diameter. Define f（G） =diamD. In this paper, we concentrate on exploring the minimum diameter of Km ∨ Kn（m ≥ 1, n ≥ 1）. Some special cases are known： f（Km ∨ Kn） = ∞, 2, 3, where m = landn ≥ 1, m = 2 or m ≥ 4 andn = 1, m=3 and n = 1, respectively. So we only consider the case when m ≥ 2 and n ≥ 2. The following results are obtained. （1） f（Km ∨ Kn） = 3, where m = 2, 3, n ≥ 2 and m = n = 4. （2） f（Km ∨ Kn） = 2, m where m ≥ 5 andmisodd, 2 ≤ n ≤ （m[m/2]）-m. （3） f（Km ∨ Kn） = 2, whereto ≥ 4 and m≡ 0（rood4）, 2 ≤ n ≤ （m m/2）-（m/2＋1）. （4） ]（Km ∨ Kn） = 2, where m ≥ 6 and m ≡ 2（mod4）, 2 ≤ n ≤ （m m/2）-m/2. （5）/（Km ∨ Kn） = 3, where m ≥ 4, n 〉 （m[m/2]）.
基金Project(531107040300)supported by the Fundamental Research Funds for the Central Universities in ChinaProject(51176045)supported by the National Natural Science Foundation of China
文摘In order to explain the oscillation heat transfer dynamics of closed loop oscillation heat pipe (CLOHP) with two liquid slugs,analysis on the forces and heat transfer process of the partial gas-liquid phase system involving multiple parameters was carried out,and a new type oscillation heat transfer dynamic model of the CLOHP was set up based on conservation laws of mass,momentum and energy.Application results indicate that its oscillation heat transfer dynamics features depend largely on the filling rate,pipe diameter and difference in temperature.Besides,oscillation intensity and transfer performance can be improved to a large extent by increasing the temperature difference properly and enlarging the pipe diameter within a certain range under a certain filling rate.
基金Project(2013BAB14B05)supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China
文摘The properties and thickness of the bubbles in the froth control the flotation process. There is no work showing how to measure bubble film composition and thickness by a straightforward manner. In this work, a novel approach, a custom-designed bubble cell associated with layer interferometry(in the UV-vis region) and FT-IR spectroscopy was used to investigate the effect of solid particle type(hydrophilic vs hydrophobic), concentration and bubble diameter on stability of a bubble blown in air. Stability was quantified by measuring bubble lifetime and hydrated film thickness. Kerosene with silicone oil as a foaming agent was used to evaluate the impact of bubble diameter(test series I). Frother solutions(MIBC, Dowfroth 250, Hexanol and F-150) were used for the solid type concentration experiments(test series II). In the first series of experiments, it was determined that as the diameter of a bubble increased from 10 to 25 mm, so did the hydrated film thickness from 350 to 1000 nm. In the second series, as the silica concentration increased(0 to 10%), an increase in bubble lifetime and hydrated film thickness was resulted(130%-250%). An impact of solid hydrophobicity was found but to a lesser degree than expected. It is possible that the small particle size(<0.1 m) of silica was responsible for this behavior. The findings are used to interpret the effect of solids in flotation froth.
文摘Essential oils are effective antimicrobials on important some pathogenic bacteria and can be added packaging materials due to absorb various surfaces. In this study, the aim is to determinate of antimicrobial effects of methyl cellulose films with containing various proportions thyme, rosemary, coriander, basil and pimento berry oils （1%, 2%, 3% and 4% g/cc） against important bacteria as a surface contaminant Listeria innocua by in vitro. For this purpose, 1 cm diameter discs were cut from methyl cellulose films containing essential oils and inhibition zone diameter which were measured by the agar diffusion method. As the results of these analyses, all prepared active edible methyl cellulose films were antimicrobial effects on Listeria innocua. The most powerful antimicrobial effect achieved with methyl cellulose film including coriander oil on Listeria innocua. And also the weakest antimicrobial effect achieved with methyl cellulose film including rosemary oil on Listeria. All results were significant by statistically （p 〈 0.01） and all analyses were replicated in three times.
基金Supported by the National Key Basic Research Program of China(No.2014CB046405)Key Projects in the National Science&Technology Pillar Program during the Twelfth Five-year Plan of China(No.2014BAF02B00,2011BAF09B04)
文摘This paper presents an adaptive friction compensation method based on LuGre model for large diameter electric-hydraulic proportional valves in which the valve core contains friction.A mathematic model of the electric-hydraulic proportional valve is established,and the friction characteristics are described based on the LuGre model.The global asymptotic stability of the control system with the adaptive friction compensation controller is guaranteed over Lyapunov theorem.The adaptive compensation of the friction on LuGre friction model is verified by simulation and experiment.The steady-state error is about [-4.23 × 10^(-5)m,5.91 × 10^(-5)m]and[-2.5 × 10^(-4)m,2.6 ×10^(-4) m] on simulation and experiment,the position tracking accuracy is higher,and the lag time of the main valve through the dead zone is shorter.The result proves that the adaptive friction compensation method can effectively compensate for the negative effects of nonlinear friction.
文摘Because pipeline has large pipe diameter, large throughout and high pressure, once pipeline leakage accident happens, the damage is quite serious. In addition, pipeline leakage accident caused by man-made drilling oil stolen every year results in huge economic losses on oilfield. Therefore, a real-time and accurate pipeline leak detection and location system not only can effectively decrease leakage loss and reduce the waste of manpower and material resources in patrolling work, but also is conductive to the management of oil pipeline and improvement of economic efficiency of enterprise. The paper determines leak detection and location project giving priority to negative pressure wave and supplemented by flow parameter analysis. The method not only can judge the accidence of leakage timely and accurately, but also can effectively avoid leakage false alarm caused by start or stop pumps in pipeline.
基金supported by National Natural Science Foundation of China (Grant No. 11271343)
文摘In this paper, we study the complete bounded λ-hypersurfaces in the weighted volume-preserving mean curvature flow. Firstly, we investigate the volume comparison theorem of complete bounded λ-hypersurfaces with |A|≤α and get some applications of the volume comparison theorem. Secondly, we consider the relation among λ, extrinsic radius k, intrinsic diameter d, and dimension n of the complete λ-hypersurface,and we obtain some estimates for the intrinsic diameter and the extrinsic radius. At last, we get some topological properties of the bounded λ-hypersurface with some natural and general restrictions.
基金Project supported by the National Natural Science Foundation of China (No.31571918)Hong Kong, Macao, and Taiwan Scientific and Technological Cooperation Projects (No.2015DFT30150) of Chinathe Zhejiang Provincial Department of Education (No.Y201533676), China
文摘Immunomagnetic bead（IMB）-based enzyme-linked immunosorbent assay（ELISA） has been the tool frequently used for protein detection in research and clinical laboratories.For most ELISA reactions the recommended dosage of IMBs is usually according to their weight（mg） or mass fraction（w/v） instead of the bead number.Consequently, the processes occurring in the immediate vicinity of the IMBs have always been ignored by researchers and they cannot be revealed in detail during the ELISA reaction.In this paper, we established the relationship between number of IMBs and colorimetric results, and further proposed a new concept of ＂nominal effective immunoreaction volume（NEIV）＂ to characterize a single IMB during ELISA reaction.Results showed that the NEIV of a single IMB has a constant value, which is unrelated to the amount of beads and the concentration of antigen.Optimal results of the colorimetric ELISA are achieved when the incubation volume meets each IMB＇s NEIV and is no longer enhanced by increasing the incubation volume.Thus, the reliable and relatively precise number of IMBs for ELISA detection during practical application could be determined.Most importantly, a study using IMB＇s NEIV would lay the foundation for a kinetics analysis of IMBs and antigens for future study.
