The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing(MRF)and surface of MRF,as well as interaction between efficie...The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing(MRF)and surface of MRF,as well as interaction between efficiency and surface.Based on theoretical and experimental research,the law of material removal was explored and a new process variable based material removal model(PVMR)was proposed.The experimental findings demonstrate that PVMR reveals the law of the material removal with introduction of three concepts and makes a material removal function z(y i)where the magnetorheological finishing process parameters are considered since they are easy to control and adjust.So the material function of this model is quadratic curve function which is readily suitable for stability and online control magnetorheological finishing.展开更多
AIM To investigate the possible long-term psychological harm of participating in colorectal cancer(CRC)screening in Norway.METHODS In a prospective, randomized trial, 14294 participants(aged 50-74 years) were invited ...AIM To investigate the possible long-term psychological harm of participating in colorectal cancer(CRC)screening in Norway.METHODS In a prospective, randomized trial, 14294 participants(aged 50-74 years) were invited to either flexible sigmoidoscopy(FS) screening, or a faecal immunochemical test(FIT)(1:1). In total, 4422 screening participants(32%) completed the questionnaire, which consisted of the Hospital Anxiety and Depression Scale and the SF-12, a generic health-related quality of life(HRQOL) measurement, when invited to screening and one year after the invitation. A control group of 7650 individuals was invited to complete the questionnaire only, at baseline and one year after, and 1911(25%) completed the questionnaires.RESULTS Receiving a positive or negative screening result and participating in the two different screening modalities did not cause clinically relevant mean changes in anxiety, depression or HRQOL after one year. FS screening, but not FIT, was associated with an increased probability of being an anxiety case(score ≥ 8) at the one-year follow-up(5.6% of FS participants transitioned from being not anxious to anxious, while 3.0% experienced the reverse). This increase was moderately significantly different from the changes in the control group(in which the corresponding numbers were 4.8% and 4.5%, respectively), P = 0.06. CONCLUSION Most individuals do not experience psychological effects of CRC screening participation after one year, while FS participation is associated with increased anxiety for a smaller group.展开更多
The purpose, classification, required accuracy and surveying methods of control work for close range photogrammetry have been briefly stated. The different methods for definition of space, object coordinate system are...The purpose, classification, required accuracy and surveying methods of control work for close range photogrammetry have been briefly stated. The different methods for definition of space, object coordinate system are also reviewed. It is suggested that the habitu-ally-practised rotation angle system for aerophotogrammetry in China should be used for the future teaching and resaarching work in the close range photogrammetry, and that the rotation angle system for terrestrial deformation photogrammetry should be left out in order to avoid the confuse and reduce the amount of expanse for making softwares. It has been emphasized that there are three improtant aspects in the close range control work with high accurary using the conventional method of engineering surveying: the use of standard scale for measurement of distance between two general stations, the accurate determination of start direction line between two general stations and the handling method of influence of 2C change. A method for setting up industrial surveying control net with extra-high accuracy ±(0.05–0.20) mm is presented by the author. This kind of industrial control net is necessary for batch process of large industrial components with purposes of measurement, inspect and lofting. There are some special methods of control work in the close range photogrammetry, including two methods presented by the author.展开更多
This paper focuses on the dynamic control of distillation column with side reactors(SRC) for methyl acetate production. To obtain the optimum integrated structure and steady state simulation, the systematic design app...This paper focuses on the dynamic control of distillation column with side reactors(SRC) for methyl acetate production. To obtain the optimum integrated structure and steady state simulation, the systematic design approach based on the concept of independent reaction amount is applied to the process of SRC for methyl acetate production. In addition to the basic control loops, multi-variable model predictive control modular with methyl acetate concentration and temperature of sensitive plate is designed. Then, based on process simulation software Aspen Plus, dynamic simulation of SRC for methyl acetate production is used to verify the effectiveness of the control scheme.展开更多
A cable dome has no stiffness or load carrying capacity unless it has been prestressed.Analyses of cable domes are based on successful prestressing designs,making force finding analysis very important.A new force find...A cable dome has no stiffness or load carrying capacity unless it has been prestressed.Analyses of cable domes are based on successful prestressing designs,making force finding analysis very important.A new force finding method named the imbal-ance force iterative method is proposed,which can overcome some limitations of the integrity feasible prestressing method.For instance,even if groups are assigned by mistake,the pretension distribution that satisfies the known geometry form can also be found.This method possess good stability and calculation efficiency,and a case study indicates that it is applicable to the force finding of large and complicated cable domes.On the other hand,form finding analysis of cable domes is also a key engineering problem.However,rigid displacement occurs in this process,which makes the analysis more complex.In this pa-per,the dynamic relaxation method was selected,and the problem of rigid displacement was therefore effectively solved.The method includes two steps:first,the stretching cables are released,and secondly,an axial force is imposed on the two ends of each released cable.This method is convenient in its calculation and clear in its conception.A case study indicates that the method is suitable for the simulation of the construction process of various cable domes and cable-strut tension structures.Moreover,a form finding experiment was conducted on a model of a cable dome with a diameter of 4.8 m by tensing diagonal cables.The behavior of the model in the form finding process was investigated.The experimental results indicate that the ini-tial lengths of members and prestress loss are key issues in cable domes design.The results also prove that the methods of form finding and force finding proposed in this paper are reliable and effective.展开更多
基金National Science and Technology Major Project,China(No.2009ZX04001-101)National Program on Key Basic Research Project(973Program)(No.2009CB724400)Shanghai Leading Academic Discipline Project,China(No.B602)
文摘The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing(MRF)and surface of MRF,as well as interaction between efficiency and surface.Based on theoretical and experimental research,the law of material removal was explored and a new process variable based material removal model(PVMR)was proposed.The experimental findings demonstrate that PVMR reveals the law of the material removal with introduction of three concepts and makes a material removal function z(y i)where the magnetorheological finishing process parameters are considered since they are easy to control and adjust.So the material function of this model is quadratic curve function which is readily suitable for stability and online control magnetorheological finishing.
基金Supported by the Ministry of Health and Care Services in Norway
文摘AIM To investigate the possible long-term psychological harm of participating in colorectal cancer(CRC)screening in Norway.METHODS In a prospective, randomized trial, 14294 participants(aged 50-74 years) were invited to either flexible sigmoidoscopy(FS) screening, or a faecal immunochemical test(FIT)(1:1). In total, 4422 screening participants(32%) completed the questionnaire, which consisted of the Hospital Anxiety and Depression Scale and the SF-12, a generic health-related quality of life(HRQOL) measurement, when invited to screening and one year after the invitation. A control group of 7650 individuals was invited to complete the questionnaire only, at baseline and one year after, and 1911(25%) completed the questionnaires.RESULTS Receiving a positive or negative screening result and participating in the two different screening modalities did not cause clinically relevant mean changes in anxiety, depression or HRQOL after one year. FS screening, but not FIT, was associated with an increased probability of being an anxiety case(score ≥ 8) at the one-year follow-up(5.6% of FS participants transitioned from being not anxious to anxious, while 3.0% experienced the reverse). This increase was moderately significantly different from the changes in the control group(in which the corresponding numbers were 4.8% and 4.5%, respectively), P = 0.06. CONCLUSION Most individuals do not experience psychological effects of CRC screening participation after one year, while FS participation is associated with increased anxiety for a smaller group.
文摘The purpose, classification, required accuracy and surveying methods of control work for close range photogrammetry have been briefly stated. The different methods for definition of space, object coordinate system are also reviewed. It is suggested that the habitu-ally-practised rotation angle system for aerophotogrammetry in China should be used for the future teaching and resaarching work in the close range photogrammetry, and that the rotation angle system for terrestrial deformation photogrammetry should be left out in order to avoid the confuse and reduce the amount of expanse for making softwares. It has been emphasized that there are three improtant aspects in the close range control work with high accurary using the conventional method of engineering surveying: the use of standard scale for measurement of distance between two general stations, the accurate determination of start direction line between two general stations and the handling method of influence of 2C change. A method for setting up industrial surveying control net with extra-high accuracy ±(0.05–0.20) mm is presented by the author. This kind of industrial control net is necessary for batch process of large industrial components with purposes of measurement, inspect and lofting. There are some special methods of control work in the close range photogrammetry, including two methods presented by the author.
基金Supported by the National Natural Science Foundation of China(61673205,61503181,21727818)National Key R&D Program of China(2017YFB0307304)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20141461,BK20140953)the State Key Laboratory of Materials-Oriented Chemical Engineering Open Subject(kl16-07)
文摘This paper focuses on the dynamic control of distillation column with side reactors(SRC) for methyl acetate production. To obtain the optimum integrated structure and steady state simulation, the systematic design approach based on the concept of independent reaction amount is applied to the process of SRC for methyl acetate production. In addition to the basic control loops, multi-variable model predictive control modular with methyl acetate concentration and temperature of sensitive plate is designed. Then, based on process simulation software Aspen Plus, dynamic simulation of SRC for methyl acetate production is used to verify the effectiveness of the control scheme.
文摘A cable dome has no stiffness or load carrying capacity unless it has been prestressed.Analyses of cable domes are based on successful prestressing designs,making force finding analysis very important.A new force finding method named the imbal-ance force iterative method is proposed,which can overcome some limitations of the integrity feasible prestressing method.For instance,even if groups are assigned by mistake,the pretension distribution that satisfies the known geometry form can also be found.This method possess good stability and calculation efficiency,and a case study indicates that it is applicable to the force finding of large and complicated cable domes.On the other hand,form finding analysis of cable domes is also a key engineering problem.However,rigid displacement occurs in this process,which makes the analysis more complex.In this pa-per,the dynamic relaxation method was selected,and the problem of rigid displacement was therefore effectively solved.The method includes two steps:first,the stretching cables are released,and secondly,an axial force is imposed on the two ends of each released cable.This method is convenient in its calculation and clear in its conception.A case study indicates that the method is suitable for the simulation of the construction process of various cable domes and cable-strut tension structures.Moreover,a form finding experiment was conducted on a model of a cable dome with a diameter of 4.8 m by tensing diagonal cables.The behavior of the model in the form finding process was investigated.The experimental results indicate that the ini-tial lengths of members and prestress loss are key issues in cable domes design.The results also prove that the methods of form finding and force finding proposed in this paper are reliable and effective.
