Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF she...Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner.展开更多
In operating flotation plants, the viscosity of the pulp can vary significantly. Consequently, the resulting impact on bubble size is of interest as many plants experience seasonal changes in water temperature, or par...In operating flotation plants, the viscosity of the pulp can vary significantly. Consequently, the resulting impact on bubble size is of interest as many plants experience seasonal changes in water temperature, or particle size changes as ore hardness, mineralogy and throughput fluctuate. However, given its importance in flotation, there existed no mathematical relationship linking bubble size created in flotation machines to the key process variable of fluid viscosity. In this study, a program of investigation to develop such a model was utilizing a pilot-scale mechanical flotation machine, to investigate the effect of water viscosity due to temperature on bubble size distribution. The bubble sizes were determined using a specific bubble viewer and imaging technology. The temperature itself was varied as a method for introducing significant viscosity change. The viscosity-temperature effect introduced a correspondingly significant change in the water viscosity（1619 to 641 μPa·s）. It is suggested that a considerably stronger relationship may exist, yielding D32 versus（μ/μ20）0.776, and hence viscosity becomes an important design consideration for plants operating where pulp temperature fluctuations, very small particles or high solid fractions are present.展开更多
The method proposed by Stammer (1998) is modified using eddy statistics from altimeter observation to obtain more realistic eddy diffusivity (K) for the North Pacific. Compared with original estimates, the modified K ...The method proposed by Stammer (1998) is modified using eddy statistics from altimeter observation to obtain more realistic eddy diffusivity (K) for the North Pacific. Compared with original estimates, the modified K has remarkably reduced values in the Kuroshio Extension (KE) and North Equatorial Counter Current (NECC) regions, but slightly enhanced values in the Subtropical Counter Current (STCC) region. In strong eastward flow areas like the KE and NECC, owing to a large difference between mean flow velocity and propagation velocity of mesoscale eddies, tracers inside the mesoscale eddies are transported outside rapidly by advection, and mixing length L is hence strongly suppressed. The low eddy probability (P) is also responsible for the reduced K in the NECC area. In the STCC region, however, L is mildly suppressed and P is very high, so K there is enhanced. The zonally-averaged K has two peaks with comparable magnitudes, in the latitude bands of the STCC and KE. In the core of KE, because of the reduced values of P and L, the zonally-averaged K is a minimum. Zonally-integrated eddy heat transport in the KE band, calculated based on the modified K, is much closer to the results of previous independent research, indicating the robustness of our modified K. The map of modified K provides useful information for modeling studies in the North Pacific.展开更多
Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly. This step involves generating multiple thin layers of polymeric coatings on the vehicle surface thr...Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly. This step involves generating multiple thin layers of polymeric coatings on the vehicle surface through paint spray and curing in a multistage, dynamically changing environment. Traditionally, the quality control is solely post-process inspection based, and process operational adjustment is only experience based, thus the manufacturing may not be （highly） sustainable. In this article, a multiscale system modeling and analysis methodology is introduced for achieving a sustainable application of polymeric materials through paint spray and film curing in automotive surface coating manufacturing. By this methodology, the correlations among paint material, application processes and coating performance can be identified. The model-based analysis allows a comprehensive and deep study of the dynamic behaviors of the material, process, and product in a wide spectrum of length and time. Case studies illustrate the efficacy of the methodology for sustainable manufacturing.展开更多
Based on the working principles of particle bed comminution, particles produced by high-pressure grinding rolls （HPGR） have surface properties different from particles produced by other grinding patterns, which exer...Based on the working principles of particle bed comminution, particles produced by high-pressure grinding rolls （HPGR） have surface properties different from particles produced by other grinding patterns, which exert great influence on mineral flotation. Flotation performances of calcite particles under different grinding patterns involving the use of HPGR, a jaw crusher, a dry ball mill, a wet ball mill, and a wet rod mill were studied using single mineral flotation tests. The surface properties of the particles under different grinding patterns were characterized to determine the flotation performance variation in terms of specific surface area, particle size distribution, AFM, XPS, and zeta potential. The results show that particles ground by HPGR exhibited improved flotation performance within the lower range of grinding fineness in both NaOL and dodecyl amine flotation systems compared to the particles prepared using other grinding patterns. Specific surface area, particle size distribution, surface roughness, Fe（III） contamination, binding energy, and zeta potential are greatly influenced by grinding patterns, which is the main cause of the flotation performance variation.展开更多
This study presents a numerical method for optimizing hull form in calm water with respect to total drag which contains a viscous drag and a wave drag. The ITTC 1957 model-ship correlation line was used to predict fri...This study presents a numerical method for optimizing hull form in calm water with respect to total drag which contains a viscous drag and a wave drag. The ITTC 1957 model-ship correlation line was used to predict frictional drag and the corrected linearized thin-ship theory was employed to estimate the wave drag The evolution strategy （ES） which is a member of the evolutionary algorithms （EAs） family obtains an optimum hull form by considering some design constraints. Standard Wigley hull is considered as an initial hull in optimization procedures for two test cases and new hull forms were achieved at Froude numbers 0.24, 0.316 and 0.408. In one case the ES technique was ran for the initial hull form, where the main dimensions were fixed and the only variables were the hull offsets. In the other case in addition to hull offsets, the raain dimensions were considered as variables that are optimized simultaneously. The numerical results of optimization procedure demonstrate that the optimized hull forms yield a reduction in total drag.展开更多
In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inhere...In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.展开更多
Highly active MCM-41 supported nickel phosphide catalysts for hydrodesulfurization （HDS） were synthesized by two different phosphorus sources, in which the surface of Ni2P catalysts were modified by air instead of b...Highly active MCM-41 supported nickel phosphide catalysts for hydrodesulfurization （HDS） were synthesized by two different phosphorus sources, in which the surface of Ni2P catalysts were modified by air instead of being passivated by O2/N2 mixture. In addition, the catalysts need not be activated with flowing H2 （30 ml·min^-1） at 500℃ for 2 h prior to reaction as traditional method. X-ray diffraction （XRD）, X-ray photoelectro spectroscopy （XPS）, N2-adsorption specific surface area measurements and CO chemisorption were used to characterize the resulting catalysts. The effect of modification with air on the surface of the catalysts for HDS performance was investigated. Results showed that the surface modification with air can promote the formation of smaller Ni2P particles and more active Ni sites on surface of catalysts. At 3.0 MPa and 613 K, the dibenzothiophene （DBT） conversion of the catalysts modified with air was 98.7%, which was 7.1% higher than that of catalyst passivated by O2/N2 mixture. The higher activities of Ni2P（x）/M41-O catalysts can be attributed to the smaller Ni2P particles sizes and the increased hydrogen dissociation activity due to the surface modification.展开更多
This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive cor...This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive correlation exists between the preceding summer NAO and the early autumn RCC on the interannual timescale. In order to understand the physical mechanism between them, the role of ocean was investigated. It was found that the strong summer NAO can induce a tripole sea surface temperature anomaly(SSTA) in the North Atlantic; this SSTA pattern can persist until early autumn. The diagnostic analysis showed that the tripole SSTA pattern excites a downstream Atlantic-Eurasian(AEA) teleconnection, which contributes to an increase in RCC. The circulation anomalies related to SSTA caused by the weak NAO are opposite, so the RCC is less than normal. The results imply that the preceding summer NAO may be regarded as a forecast factor for the early autumn RCC.展开更多
文摘Experimental study has been conducted for an interstitial free(IF) sheet steel on its surface roughness evolution and formability with respect to grain size and sheet thickness effect. The surface roughness of IF sheet steel is proportional to effective strain, grain size and inversely proportional to sheet thickness; the larger grain reduces the formability by accelerating the surface roughening rate and enhance formability by raising the workhardening rate, while the latter effect plays the dominate role. The grain size effect on surface roughening and formability is more obvious when the sheets are thinner.
基金the Chair in Mineral Processing at McGill University, under the Collaborative Research and Development Program of NSERC (Natural Sciences and Engineering Research Council of Canada) with industrial sponsorship from Vale, Teck Cominco, Xstrata Process Support, Agnico-Eagle, Shell Canada, Barrick Gold, COREM, SGS Lakefield Research and Flottec
文摘In operating flotation plants, the viscosity of the pulp can vary significantly. Consequently, the resulting impact on bubble size is of interest as many plants experience seasonal changes in water temperature, or particle size changes as ore hardness, mineralogy and throughput fluctuate. However, given its importance in flotation, there existed no mathematical relationship linking bubble size created in flotation machines to the key process variable of fluid viscosity. In this study, a program of investigation to develop such a model was utilizing a pilot-scale mechanical flotation machine, to investigate the effect of water viscosity due to temperature on bubble size distribution. The bubble sizes were determined using a specific bubble viewer and imaging technology. The temperature itself was varied as a method for introducing significant viscosity change. The viscosity-temperature effect introduced a correspondingly significant change in the water viscosity（1619 to 641 μPa·s）. It is suggested that a considerably stronger relationship may exist, yielding D32 versus（μ/μ20）0.776, and hence viscosity becomes an important design consideration for plants operating where pulp temperature fluctuations, very small particles or high solid fractions are present.
基金Supported by the Major Program of the National Natural Science Foundation of China (No.40890153)the National High Technology Research and Development Program of China (863 Program) (No.2008AA09A402)
文摘The method proposed by Stammer (1998) is modified using eddy statistics from altimeter observation to obtain more realistic eddy diffusivity (K) for the North Pacific. Compared with original estimates, the modified K has remarkably reduced values in the Kuroshio Extension (KE) and North Equatorial Counter Current (NECC) regions, but slightly enhanced values in the Subtropical Counter Current (STCC) region. In strong eastward flow areas like the KE and NECC, owing to a large difference between mean flow velocity and propagation velocity of mesoscale eddies, tracers inside the mesoscale eddies are transported outside rapidly by advection, and mixing length L is hence strongly suppressed. The low eddy probability (P) is also responsible for the reduced K in the NECC area. In the STCC region, however, L is mildly suppressed and P is very high, so K there is enhanced. The zonally-averaged K has two peaks with comparable magnitudes, in the latitude bands of the STCC and KE. In the core of KE, because of the reduced values of P and L, the zonally-averaged K is a minimum. Zonally-integrated eddy heat transport in the KE band, calculated based on the modified K, is much closer to the results of previous independent research, indicating the robustness of our modified K. The map of modified K provides useful information for modeling studies in the North Pacific.
基金Supported in part by US NSF (CBET 0647113 and 0730383, CMMI 0700178, and DUE 0736739)the Institute of Manufacturing Research of Wayne State University.
文摘Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly. This step involves generating multiple thin layers of polymeric coatings on the vehicle surface through paint spray and curing in a multistage, dynamically changing environment. Traditionally, the quality control is solely post-process inspection based, and process operational adjustment is only experience based, thus the manufacturing may not be （highly） sustainable. In this article, a multiscale system modeling and analysis methodology is introduced for achieving a sustainable application of polymeric materials through paint spray and film curing in automotive surface coating manufacturing. By this methodology, the correlations among paint material, application processes and coating performance can be identified. The model-based analysis allows a comprehensive and deep study of the dynamic behaviors of the material, process, and product in a wide spectrum of length and time. Case studies illustrate the efficacy of the methodology for sustainable manufacturing.
基金Project(2013EG132088)supported by Special Program for Research Institutes of the Ministry of Science and Technology,ChinaProject(12010402c187)supported by Key Science and Technology Program of Anhui Province,ChinaProject(GJKJ-14-89)supported by Science and Technology Program of Nanchang Institute of Science and Technology,China
文摘Based on the working principles of particle bed comminution, particles produced by high-pressure grinding rolls （HPGR） have surface properties different from particles produced by other grinding patterns, which exert great influence on mineral flotation. Flotation performances of calcite particles under different grinding patterns involving the use of HPGR, a jaw crusher, a dry ball mill, a wet ball mill, and a wet rod mill were studied using single mineral flotation tests. The surface properties of the particles under different grinding patterns were characterized to determine the flotation performance variation in terms of specific surface area, particle size distribution, AFM, XPS, and zeta potential. The results show that particles ground by HPGR exhibited improved flotation performance within the lower range of grinding fineness in both NaOL and dodecyl amine flotation systems compared to the particles prepared using other grinding patterns. Specific surface area, particle size distribution, surface roughness, Fe（III） contamination, binding energy, and zeta potential are greatly influenced by grinding patterns, which is the main cause of the flotation performance variation.
基金marine research institute (MRC) of AUT for some financial support of this project
文摘This study presents a numerical method for optimizing hull form in calm water with respect to total drag which contains a viscous drag and a wave drag. The ITTC 1957 model-ship correlation line was used to predict frictional drag and the corrected linearized thin-ship theory was employed to estimate the wave drag The evolution strategy （ES） which is a member of the evolutionary algorithms （EAs） family obtains an optimum hull form by considering some design constraints. Standard Wigley hull is considered as an initial hull in optimization procedures for two test cases and new hull forms were achieved at Froude numbers 0.24, 0.316 and 0.408. In one case the ES technique was ran for the initial hull form, where the main dimensions were fixed and the only variables were the hull offsets. In the other case in addition to hull offsets, the raain dimensions were considered as variables that are optimized simultaneously. The numerical results of optimization procedure demonstrate that the optimized hull forms yield a reduction in total drag.
基金Project (No. DEARS/CASR/R-01/2001/D-934 (30)) supported by Directorate of Advisory Extension and Research Services (DAERS), Committee for Advanced Studies & Research (CASR), BUET, Dhaka, Bangladesh
文摘In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.
基金Supported by the National Natural Science Foundation of China(21276048)the Project of Education Department of Heilongjiang Province,China(12541060)the Graduate Innovation Project of Northeast Petroleum University,China(YJSCX2016-019NEPU)
文摘Highly active MCM-41 supported nickel phosphide catalysts for hydrodesulfurization （HDS） were synthesized by two different phosphorus sources, in which the surface of Ni2P catalysts were modified by air instead of being passivated by O2/N2 mixture. In addition, the catalysts need not be activated with flowing H2 （30 ml·min^-1） at 500℃ for 2 h prior to reaction as traditional method. X-ray diffraction （XRD）, X-ray photoelectro spectroscopy （XPS）, N2-adsorption specific surface area measurements and CO chemisorption were used to characterize the resulting catalysts. The effect of modification with air on the surface of the catalysts for HDS performance was investigated. Results showed that the surface modification with air can promote the formation of smaller Ni2P particles and more active Ni sites on surface of catalysts. At 3.0 MPa and 613 K, the dibenzothiophene （DBT） conversion of the catalysts modified with air was 98.7%, which was 7.1% higher than that of catalyst passivated by O2/N2 mixture. The higher activities of Ni2P（x）/M41-O catalysts can be attributed to the smaller Ni2P particles sizes and the increased hydrogen dissociation activity due to the surface modification.
基金supported jointly by the National Basic Research Program of China(973 program,Grant No.2013CB340203)the National Natural Science Foundation of China(NSFC)(Grant Nos.41290255 and 41205046)
文摘This study examined the impact of the preceding boreal summer(June–August) North Atlantic Oscillation(NAO) on early autumn(September) rainfall over Central China(RCC). The results show that a significant positive correlation exists between the preceding summer NAO and the early autumn RCC on the interannual timescale. In order to understand the physical mechanism between them, the role of ocean was investigated. It was found that the strong summer NAO can induce a tripole sea surface temperature anomaly(SSTA) in the North Atlantic; this SSTA pattern can persist until early autumn. The diagnostic analysis showed that the tripole SSTA pattern excites a downstream Atlantic-Eurasian(AEA) teleconnection, which contributes to an increase in RCC. The circulation anomalies related to SSTA caused by the weak NAO are opposite, so the RCC is less than normal. The results imply that the preceding summer NAO may be regarded as a forecast factor for the early autumn RCC.
