In three-dimensional television (3DTV), an interactive free viewpoint selection application has received more attention so far. This paper presents a novel method that synthesizes a free-viewpoint based on multiple te...In three-dimensional television (3DTV), an interactive free viewpoint selection application has received more attention so far. This paper presents a novel method that synthesizes a free-viewpoint based on multiple textures and depth maps in multi-view camera configuration. This method solves the cracks and holes problem due to sampling rate by performing an inverse warping to retrieve texture images. This step allows a simple and accurate re-sampling of synthetic pixels. To enforce the spatial consistency of color and remove the pixels wrapped incorrectly because of inaccuracy depth maps, we propose some processing steps. The warped depth and warped texture images are used to classify pixels as stable, unstable and disoccluded pixels. The stable pixels are used to create an initial new view by weighted interpolation. To refine the new view, Graph cuts are used to select the best candidates for each unstable pixel. Finally, the remaining disoccluded regions are filled by our inpainting method based on depth information and texture neighboring pixel values. Our experiment on several multi-view data sets is encouraging in both subjective and objective results. Furthermore, our proposal can flexibly use more than two views in multi-view system to create a new view with higher quality.展开更多
Cutting tests were done using a test bed designed to measure pick cutting forces when cutting coal and rock.The test equipment has a drum with two starting helical vanes.Cutting forces on a pick were measured as a fun...Cutting tests were done using a test bed designed to measure pick cutting forces when cutting coal and rock.The test equipment has a drum with two starting helical vanes.Cutting forces on a pick were measured as a function of coal compressive strength,pick carbide tip diameter and the cutting depth per drum revolution.The results show that the cutting force is linearly related to the compressive strength.The relationship between the cutting force and both the carbide tip diameter and the cutting depth are exponential.Fluctuation in the cutting force does not increase with coal compressive strength but it has a linear relationship to tip diameter.A plot of cutting force fluctuations versus the cutting depth follows a sigmoidal curve.Based on the analysis of these test results a theoretical basis is supplied for design and effective use of shearer drums.展开更多
This paper describes the application of orthogonal test design coupled with non-linear regression analysis to optimize abrasive suspension jet （AS J） cutting process and construct its cutting model. Orthogonal test ...This paper describes the application of orthogonal test design coupled with non-linear regression analysis to optimize abrasive suspension jet （AS J） cutting process and construct its cutting model. Orthogonal test design is applied to cutting stainless steel. Through range analysis on experiment results, the optimal process conditions for the cutting depth and the kerr ratio of the bottom width to the top width can be determined. In addition, the analysis of ranges and variances are all employed to identify various factors： traverse rate, working pressure, nozzle diameter, standoff distance which denote the importance order of the cutting parameters affecting cutting depth and the kerf ratio of the bottom width to the top width. ~rthermore, non-linear regression analysis is used to establish the mathematical models of the cutting parameters based on the cutting depth and the kerr ratio. Finally, the verification experiments of cutting parameters＇ effect on cutting performance, which show that optimized cutting parameters and cutting model can significantly improve the prediction of the cutting ability and quality of ASJ.展开更多
One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets...One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption.展开更多
A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cut...A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.展开更多
This study deals with Nd：YAG laser cutting nonmetallic materials, which is one of the most important and popular industrial applications of laser. The main theme is to evaluate the effects of Nd：YAG laser beam power...This study deals with Nd：YAG laser cutting nonmetallic materials, which is one of the most important and popular industrial applications of laser. The main theme is to evaluate the effects of Nd：YAG laser beam power besides work piece scanning speed. For approximate cutting depth, a theoretical study is conducted in terms of material property and cutting speed. Results show a nonlinear relation between the cutting depth and input energy. There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s. An extra energy is utilized in the deep cutting. It is inferred that as the laser power increases, cutting depth increases. The experimental outcomes are in good agreement with theoretical results. This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting, scribing, trimming, engraving, and marking nonmetallic materials.展开更多
Centroid depth of earthquakes is essential for seismic hazard mitigation. But, various studies provided different solutions for the centroid depth of the damaging 2013 Lushan earthquake, thus hindering further studies...Centroid depth of earthquakes is essential for seismic hazard mitigation. But, various studies provided different solutions for the centroid depth of the damaging 2013 Lushan earthquake, thus hindering further studies of the earthquake processes. To resolve its centroid depth and assess the uncertainties, we apply the teleseismic cut and paste method to invert for centroid depth with teleseismic body waves in the epicentral distance of 300-90~. We performed the inversion for P waves only as well the case of both P and SH waves and found that both cases lead to depth solutions with difference less than 0.5 km. We also investigated the effects on depth inversion from azimuth gap of seismic stations, source duration, and comer fre- quency of filter. These various tests show that even azi- muthal distribution of seismic stations is helpful for accurate depth inversion. It is also found that estimate of centroid depth is sensitive to source duration. Moreover, the depth is biased to larger values when corner frequency of low-pass filter is very low. The uncertainty in the velocity model can also generate some error in the depth estimation （- 1.0 km）.With all the above factors consid- ered, the centroid depth of Lushan earthquake is proposed to be around 12 km, with uncertainty about 2 km.展开更多
CFRP （carbon fiber reinforced plastic）, which is composed of carbon fibers in a resin matrix, is an extremely strong and light composite material that has found use in the aerospace and automotive industries. CFRP b...CFRP （carbon fiber reinforced plastic）, which is composed of carbon fibers in a resin matrix, is an extremely strong and light composite material that has found use in the aerospace and automotive industries. CFRP boards are very difficult to machine using common machining processes. Various machining artifacts, such as burrs and delamination, occur frequently when machining CFRP. Adequate techniques for machining CFRP have not yet been established. Recently, electroplated diamond wire machining technology has found use in cutting hard, brittle materials such as silicon and sapphire. In this study, we used an electroplated diamond wire saw to cut a CFRP workpiece. We quantified the cutting forces imposed on the workpiece and observed the surface state of the workpiece after cutting. We demonstrated that an electroplated diamond wire tool is suitable for the high-quality machining of CFRP boards.展开更多
In precision machining processes such as grinding,for example,analysis of machined surface is important one of most parameters to evaluate process performance.Equally important is to perform tribological analysis to u...In precision machining processes such as grinding,for example,analysis of machined surface is important one of most parameters to evaluate process performance.Equally important is to perform tribological analysis to understand chip formation and abrasive wheel wear,thus enabling manufacturing of components free of thermal damages.In grinding,due to high hardness of abrasive grains that remove material from workpiece in chip form and very low values of radial depth of cut,combination of low roughness values and tight dimensional tolerances is attained.Accordingly,the parameters involved in this process are determinant in surface quality that is primarily evaluated in terms of surface roughness and workpiece functionality.In this work,surface roughness(Rt parameter)and scanning electron microscope(SEM)images of ground surfaces of the AISI 420 martensitic stainless steel samples were evaluated.Tests were carried out in surface grinding with a white aluminum oxide wheel and an environmentally-friendly semisynthetic water-soluble coolant.Two values of radial depth of cut(10μm and 25μm)were tested.The results showed that the highest roughness values,deeper grooves on the machined surfaces as well as poorer surface quality were obtained after grinding under the severest cutting conditions.展开更多
文摘In three-dimensional television (3DTV), an interactive free viewpoint selection application has received more attention so far. This paper presents a novel method that synthesizes a free-viewpoint based on multiple textures and depth maps in multi-view camera configuration. This method solves the cracks and holes problem due to sampling rate by performing an inverse warping to retrieve texture images. This step allows a simple and accurate re-sampling of synthetic pixels. To enforce the spatial consistency of color and remove the pixels wrapped incorrectly because of inaccuracy depth maps, we propose some processing steps. The warped depth and warped texture images are used to classify pixels as stable, unstable and disoccluded pixels. The stable pixels are used to create an initial new view by weighted interpolation. To refine the new view, Graph cuts are used to select the best candidates for each unstable pixel. Finally, the remaining disoccluded regions are filled by our inpainting method based on depth information and texture neighboring pixel values. Our experiment on several multi-view data sets is encouraging in both subjective and objective results. Furthermore, our proposal can flexibly use more than two views in multi-view system to create a new view with higher quality.
基金Projects 2008AA062202 supported by the Hi-tech Research and Development Program of ChinaCX08B_041Z by the Innovation Foundation of Jiangsu Graduate Students
文摘Cutting tests were done using a test bed designed to measure pick cutting forces when cutting coal and rock.The test equipment has a drum with two starting helical vanes.Cutting forces on a pick were measured as a function of coal compressive strength,pick carbide tip diameter and the cutting depth per drum revolution.The results show that the cutting force is linearly related to the compressive strength.The relationship between the cutting force and both the carbide tip diameter and the cutting depth are exponential.Fluctuation in the cutting force does not increase with coal compressive strength but it has a linear relationship to tip diameter.A plot of cutting force fluctuations versus the cutting depth follows a sigmoidal curve.Based on the analysis of these test results a theoretical basis is supplied for design and effective use of shearer drums.
基金supported by the Science and Technology Development Foundation of Shanghai Municipal Science and Technology Commission (Grant No.037252022)
文摘This paper describes the application of orthogonal test design coupled with non-linear regression analysis to optimize abrasive suspension jet （AS J） cutting process and construct its cutting model. Orthogonal test design is applied to cutting stainless steel. Through range analysis on experiment results, the optimal process conditions for the cutting depth and the kerr ratio of the bottom width to the top width can be determined. In addition, the analysis of ranges and variances are all employed to identify various factors： traverse rate, working pressure, nozzle diameter, standoff distance which denote the importance order of the cutting parameters affecting cutting depth and the kerf ratio of the bottom width to the top width. ~rthermore, non-linear regression analysis is used to establish the mathematical models of the cutting parameters based on the cutting depth and the kerr ratio. Finally, the verification experiments of cutting parameters＇ effect on cutting performance, which show that optimized cutting parameters and cutting model can significantly improve the prediction of the cutting ability and quality of ASJ.
文摘One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption.
基金co-supported by Open National Natural Science Foundation of China(No.51005183)National Science and Technology Major Project(No.2011ZX04016031)China Postdoctoral Science Foundation(No.2012M521804)
文摘A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.
基金supported by the Science Foundation of the Ministry of Science and Technology Malaysiathe Islamic Development Bank Jeddahsupport of the Universiti Teknologi Malaysia for this research work
文摘This study deals with Nd：YAG laser cutting nonmetallic materials, which is one of the most important and popular industrial applications of laser. The main theme is to evaluate the effects of Nd：YAG laser beam power besides work piece scanning speed. For approximate cutting depth, a theoretical study is conducted in terms of material property and cutting speed. Results show a nonlinear relation between the cutting depth and input energy. There is no significant effect of speed on cutting depth with the speed being larger than 30 mm/s. An extra energy is utilized in the deep cutting. It is inferred that as the laser power increases, cutting depth increases. The experimental outcomes are in good agreement with theoretical results. This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting, scribing, trimming, engraving, and marking nonmetallic materials.
文摘Centroid depth of earthquakes is essential for seismic hazard mitigation. But, various studies provided different solutions for the centroid depth of the damaging 2013 Lushan earthquake, thus hindering further studies of the earthquake processes. To resolve its centroid depth and assess the uncertainties, we apply the teleseismic cut and paste method to invert for centroid depth with teleseismic body waves in the epicentral distance of 300-90~. We performed the inversion for P waves only as well the case of both P and SH waves and found that both cases lead to depth solutions with difference less than 0.5 km. We also investigated the effects on depth inversion from azimuth gap of seismic stations, source duration, and comer fre- quency of filter. These various tests show that even azi- muthal distribution of seismic stations is helpful for accurate depth inversion. It is also found that estimate of centroid depth is sensitive to source duration. Moreover, the depth is biased to larger values when corner frequency of low-pass filter is very low. The uncertainty in the velocity model can also generate some error in the depth estimation （- 1.0 km）.With all the above factors consid- ered, the centroid depth of Lushan earthquake is proposed to be around 12 km, with uncertainty about 2 km.
文摘CFRP （carbon fiber reinforced plastic）, which is composed of carbon fibers in a resin matrix, is an extremely strong and light composite material that has found use in the aerospace and automotive industries. CFRP boards are very difficult to machine using common machining processes. Various machining artifacts, such as burrs and delamination, occur frequently when machining CFRP. Adequate techniques for machining CFRP have not yet been established. Recently, electroplated diamond wire machining technology has found use in cutting hard, brittle materials such as silicon and sapphire. In this study, we used an electroplated diamond wire saw to cut a CFRP workpiece. We quantified the cutting forces imposed on the workpiece and observed the surface state of the workpiece after cutting. We demonstrated that an electroplated diamond wire tool is suitable for the high-quality machining of CFRP boards.
文摘In precision machining processes such as grinding,for example,analysis of machined surface is important one of most parameters to evaluate process performance.Equally important is to perform tribological analysis to understand chip formation and abrasive wheel wear,thus enabling manufacturing of components free of thermal damages.In grinding,due to high hardness of abrasive grains that remove material from workpiece in chip form and very low values of radial depth of cut,combination of low roughness values and tight dimensional tolerances is attained.Accordingly,the parameters involved in this process are determinant in surface quality that is primarily evaluated in terms of surface roughness and workpiece functionality.In this work,surface roughness(Rt parameter)and scanning electron microscope(SEM)images of ground surfaces of the AISI 420 martensitic stainless steel samples were evaluated.Tests were carried out in surface grinding with a white aluminum oxide wheel and an environmentally-friendly semisynthetic water-soluble coolant.Two values of radial depth of cut(10μm and 25μm)were tested.The results showed that the highest roughness values,deeper grooves on the machined surfaces as well as poorer surface quality were obtained after grinding under the severest cutting conditions.
