TA2/TA15 graded structural material(GSM) was fabricated by the laser additive manufacturing(LAM) process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The ...TA2/TA15 graded structural material(GSM) was fabricated by the laser additive manufacturing(LAM) process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The results show that the TA2 part of exhibiting near-equiaxed grains was Widmanst?tten α-laths microstructure. The TA15 part containing large columnar grains was fine basket-weave microstructure. The graded zone was divided into four deposited layers with 3000 μm in thickness. As the distance from the TA2 part increases, the alloy element contents and the β phase volume fraction increase, the α phase volume fraction decreases and the microstructure shows the evolution from Widmanst?tten α-laths to basket-weave α-laths gradually. The micro-hardness increases from the TA2 part to the TA15 part due to the solid solution strengthening and grain boundary strengthening.展开更多
This paper reviews the land expropriation dispute research literature from three dimensions: the structure-institution analysis, action research of the dispute parties, ethics and concept research of the dispute part...This paper reviews the land expropriation dispute research literature from three dimensions: the structure-institution analysis, action research of the dispute parties, ethics and concept research of the dispute parties. The paper makes a summary on the research contents and research methods of each dimension. More- over, the contributions and the limitations are pointed out and suggestions for future展开更多
This study investigates the influence of different curing regimes on the microstructure and macro properties of ultra-high performance fiber reinforced cementitious composite (UHPFRCC), and aims to discover whether ...This study investigates the influence of different curing regimes on the microstructure and macro properties of ultra-high performance fiber reinforced cementitious composite (UHPFRCC), and aims to discover whether it is possible to produce qualified UHPFRCC using different curing regimes. A control mix of UHPFRCC is prepared. The mechanical performance and the short-term durability of the UHPFRCC matrix under three curing regimes are studied. In addition, the microstructures of the UHPFRCC matrix with different curing conditions are analyzed by combining scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). The results explore how different UHPFRCC curing regimes affect its microstructure and how the microstructure affects its macro behavior. Heat and steam curing for 3 d is succeeded to produce the UHPFRCC with nearly the same mechanical properties and durability as those of the 90 d standard curing. However, the heat cured UHPFRCC does not show great resistance to chloride-ion penetration.展开更多
A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical prope...A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction.The results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains occurs.The content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μm.Both TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-phase.However,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in microhardness.The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.展开更多
The microstructures and mechanical properties of Mg-8Li and Mg-8Li-2Al-2RE alloy sheets were evaluated after cold rolling.Both alloys contain α-phase and β-phase which consists of a solid solution of Mg in BCC Li.Th...The microstructures and mechanical properties of Mg-8Li and Mg-8Li-2Al-2RE alloy sheets were evaluated after cold rolling.Both alloys contain α-phase and β-phase which consists of a solid solution of Mg in BCC Li.The proportion ofβ-phase in both alloys is approximately 60%.Theα-phase andβ-phase are elongated approximately parallel to the rolling direction and there is no sign of recrystallization even after being annealed at 200℃for 1 h.The yield strength of Mg-8Li-2Al-2RE sheets is about 165 MPa with elongation of 35%along rolling direction,while the yield strength is about 187 MPa with elongation of 21%along the direction titled 45ü to rolling direction.Theα-phase in both alloys exhibits basal texture,and the intensity of basal texture in Mg-8Li is larger than that in Mg-8Li-2Al-2RE.However,theβ-phase shows(100)texture,and the intensity of(100)texture in Mg-8Li is twice of that in Mg-8Li-2Al-2RE.It could be attributed to the existence of RE-containing particles in Mg-8Li-2Al-2RE.展开更多
The focus of this paper is to investigate different control structures(single-loop PI control) for a dividing wall(Petlyuk) column for separating ethanol, n-propanol and n-butanol. Four control structures are studied....The focus of this paper is to investigate different control structures(single-loop PI control) for a dividing wall(Petlyuk) column for separating ethanol, n-propanol and n-butanol. Four control structures are studied. All the results are simulations based on Aspen Plus. Control structure 1(CS1) is stabilizing control structure with only temperature controllers. CS2, CS3 and CS4, containing also composition controllers, are introduced to reduce the steady state composition deviations. CS2 adds a distillate composition controller(CCDB) on top of CS1. CS3 is much more complicated with three temperature-composition cascade controllers and in addition a selector to the reboiler duty to control the maximum controller output of light impurity composition control in side stream and bottom impurity control in the prefractionator. CS4 adds another high selector to control the light impurity in the sidestream. Surprisingly, when considering the dynamic and even steady state performance of the proposed control structures, CS1 proves to be the best control structure to handle feed disturbances inserted into the three-product Petlyuk column.展开更多
Ti/Cu/Ti laminated composites were fabricated by corrugated rolling(CR) and flat rolling(FR) method.Microstructure and mechanical properties of CR and FR laminated composites were investigated by scanning electron mic...Ti/Cu/Ti laminated composites were fabricated by corrugated rolling(CR) and flat rolling(FR) method.Microstructure and mechanical properties of CR and FR laminated composites were investigated by scanning electron microscopy, numerical simulation methods, peel and tensile examinations. The effect of CR and FR was comparatively analyzed. The results showed that the CR and FR laminated composites exhibited different effective plastic strain distributions of the Ti layer and Cu layer at the interface. The recrystallization texture, prismatic texture and pyramidal texture were developed in the Ti layer by CR, while the R-Goss texture and shear texture were developed in the Cu layer by CR. The typical deformation texture components were developed in the Ti layer and Cu layer of FR laminated composites. The CR laminated composites had higher bond strength, tensile strength and ductility.展开更多
Middle East and North Africa (MENA) has been experiencing a unique demographic transition in the world especially after September 11, whilst, its social, political and economic structures have considerably remained ...Middle East and North Africa (MENA) has been experiencing a unique demographic transition in the world especially after September 11, whilst, its social, political and economic structures have considerably remained inflexible and can hardly meet the increasing demands of employment among the youth whose expectations are raised through expansion in education. In spite of various common causes for the Arab uprisings, the paper spotlights the "Youth role" and its regarded issues of "Youth Bulge", "Education" and "Unemployment" with a glimpse to the overturned regimes of "Tunisia, Egypt, Libya, and Yemen". According to published statistics these countries are among the countries with the highest rate of youth as working age population in MENA. Therefore, the paper is to present the importance and impact of youth as a social parameter in challenging political structure of the countries in the MENA and leading to topple their political systems. Thus, the paper reasons the MENA political upheavals, in general, and the mentioned countries' uprisings, in particular, can not be well understood disregarding to natural tensions between economic, population structures, and political demographic challenges. This is to be done drawing on data from different international institutions. The intervened variables such as "ethnicity, race, religion and sexuality" and international parameters have not been considered.展开更多
Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions was analyzed. ...Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions was analyzed. The resultant forces and velocities of the laminates were calculated, and the structural intensity was evaluated. The SI streamlines of carbon fiber reinforced epoxy composite laminates and the steel plates were discussed. The results show that the SI streamlines of the graphite/epoxy laminates are different from that of the steel plates, and the SI streamlines are influenced by the boundaries, the stacking sequence of the composite laminates. The change of the historical central displacement of the graphite/epoxy laminates is fasten than that of the steel plates.展开更多
An optimal control procedure is developed for the front and rear wheels of a three-axle vehicle moving on a complex typical road based on model following variable structure control strategy. The actual vehicle may be ...An optimal control procedure is developed for the front and rear wheels of a three-axle vehicle moving on a complex typical road based on model following variable structure control strategy. The actual vehicle may be considered as an uncertain system. Cornering stiffness of front and rear wheels and external disturbances are varied in a limited range. The model-following variable structure control method is used to control both front and rear wheels steering operations of the vehicle, so that steering responses of the vehicle follow from those of the reference model. By numerical results obtained from computer simulation, it is demonstrated that the control system model can cope with the effects of parameter perturbations and outside disturbances.展开更多
By inserting the variable of the exactness of corporate valuation into the classic model of Contract Theory, this paper, on the bases of the interaction of the variables of the veraciousness of corporate valuation, ma...By inserting the variable of the exactness of corporate valuation into the classic model of Contract Theory, this paper, on the bases of the interaction of the variables of the veraciousness of corporate valuation, managerial incentives and operational risks, explores the deep-seated reasons for changes in corporate structures, and draws the conclusion that the divestment of the subsidiary is beneficial to shareholders when the parent corporate is undervalued and that the relation between the parent and the subsidiary is disordered, or vice versa. This conclusion is consistent with the motives of many divestiture cases in reality.展开更多
This paper considers accounting regulation research from a structuration and cultural perspective. Therefore, accounting regulation research spans over three spheres of enquiry: (1) an accounting focus of standard-...This paper considers accounting regulation research from a structuration and cultural perspective. Therefore, accounting regulation research spans over three spheres of enquiry: (1) an accounting focus of standard-setting; (2) a cultural analysis in an empirical context; and (3) the use of a research methodology drawn from Anthony Giddens' structuration theory. In such approach, accounting regulation research analyzes the accounting regulation actors drawing upon the cultures in their standard-setting actions and interactions, referring to Giddens' three structural properties of meaning, power, and morality. The integration of these three spheres of enquiry is not entirely original. A few prior studies have similar combinations: Although they stress the uses and consequences of accounting systems in producing and reproducing organizational culture and negotiating meaning at the organizational level, this paper chooses the research approach of contextual analysis of accounting systems at more macro-societal and cultural levels. This different research interest and design provides this paper with its distinguishable characteristic from the prior similar studies.展开更多
Abstract: An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNil8-8 steel melt on 30% (mass fraction) Ni-containing alumina based composite ceramic (Ni/Al2O3) at 1 6...Abstract: An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNil8-8 steel melt on 30% (mass fraction) Ni-containing alumina based composite ceramic (Ni/Al2O3) at 1 600 ℃. The infiltration quality and interfacial bonding behavior were investigated by SEM, EDS, XRD and tensile tests. The results show that there is an obvious interfacial reaction layer between the alloying steel and the Ni/Al2O3 composite ceramic. The interfacial reactive products are (FexAly)3O4 intermetallic phase and (AlxCry)2O3 solid solution. The interracial bonding strength is as high as about 67.5 MPa. The bonding mechanism of X10CrNi 18-8 steel with the composite ceramic is that Ni inside the ceramic bodies dissolves into the alloy melt and transforms into liquid channels, consequently inducing the steel melt infiltrating and filling in the pores and the liquid channels. Moreover, the metallurgical bonding and interfacial reactive bonding also play a key role on the stability of the bonding interface.展开更多
An economic topology can have many uses to the academician, student and practitioner. Refining a topology of economic systems helps to bring together seemingly disparate characteristics and to point out potential long...An economic topology can have many uses to the academician, student and practitioner. Refining a topology of economic systems helps to bring together seemingly disparate characteristics and to point out potential long run trends. The progression of economic systems over time and also brief explanations of each system are given. We argue that most modem economic systems have some remnants of earlier forms, that is, most economies today are some mixture of what might be considered pure systems. Measurable characteristics to identify a particular system are developed that allows progress to or from a particular classification to be charted for individual countries.展开更多
Pre-heat treatment is a vital step before cold ring rolling and it has significant effect on the microstructure and mechanical properties of rolled rings.The 100Cr6 steel rings were subjected to pre-heat treatment and...Pre-heat treatment is a vital step before cold ring rolling and it has significant effect on the microstructure and mechanical properties of rolled rings.The 100Cr6 steel rings were subjected to pre-heat treatment and subsequent cold rolling process.Scanning electron microscopy and tensile tests were applied to investigate microstructure characteristic and mechanical property variations of 100Cr6 steel rings undergoing different pre-heat treatings.The results indicate that the average diameter of carbide particles,the tensile strength and hardness increase,while the elongation decreases with the decrease of cooling rate.The cooling rate has minor effect on the yield strength of sample.After cold ring rolling,the ferrite matrix shows a clear direction along the rolling direction.The distribution of cementite is more homogeneous and the cementite particles are finer.Meanwhile,the hardness of the rolled ring is higher than that before rolling.展开更多
This paper is on control system design for visual based indoor inspection by the model helicopters. For the indoor inspection system for large structures, there are some cases where it is difficult for htunans to work...This paper is on control system design for visual based indoor inspection by the model helicopters. For the indoor inspection system for large structures, there are some cases where it is difficult for htunans to work with. This paper introduces indoor inspection helicopter system with only inspection camera and prism for position sensing as payload. The control system is designed to help the operator of the inspection system to control the helicopter to designated position without much practice. The cases of the control by experienced and novice operators are compared and results show that the system has feasibility for indoor inspection system to be used by any kind of users.展开更多
基金Project(2010CB731705)supported by the National Basic Research Program of China
文摘TA2/TA15 graded structural material(GSM) was fabricated by the laser additive manufacturing(LAM) process. The chemical composition, microstructure and micro-hardness of the as-deposited GSM were investigated. The results show that the TA2 part of exhibiting near-equiaxed grains was Widmanst?tten α-laths microstructure. The TA15 part containing large columnar grains was fine basket-weave microstructure. The graded zone was divided into four deposited layers with 3000 μm in thickness. As the distance from the TA2 part increases, the alloy element contents and the β phase volume fraction increase, the α phase volume fraction decreases and the microstructure shows the evolution from Widmanst?tten α-laths to basket-weave α-laths gradually. The micro-hardness increases from the TA2 part to the TA15 part due to the solid solution strengthening and grain boundary strengthening.
基金Supported by Youth Foundation for Humanities and Social Science Research from the Ministry of Education(10YJC840078)the Fundamental Research Funds for the Central Universities(SWU1209363&SWU1409319)~~
文摘This paper reviews the land expropriation dispute research literature from three dimensions: the structure-institution analysis, action research of the dispute parties, ethics and concept research of the dispute parties. The paper makes a summary on the research contents and research methods of each dimension. More- over, the contributions and the limitations are pointed out and suggestions for future
基金The Scholarship Supported by the China Scholarship Councilthe Technical Research Program from NV Bekaert SA of Belgiumthe National Natural Science Foundation of China(No.50908047)
文摘This study investigates the influence of different curing regimes on the microstructure and macro properties of ultra-high performance fiber reinforced cementitious composite (UHPFRCC), and aims to discover whether it is possible to produce qualified UHPFRCC using different curing regimes. A control mix of UHPFRCC is prepared. The mechanical performance and the short-term durability of the UHPFRCC matrix under three curing regimes are studied. In addition, the microstructures of the UHPFRCC matrix with different curing conditions are analyzed by combining scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). The results explore how different UHPFRCC curing regimes affect its microstructure and how the microstructure affects its macro behavior. Heat and steam curing for 3 d is succeeded to produce the UHPFRCC with nearly the same mechanical properties and durability as those of the 90 d standard curing. However, the heat cured UHPFRCC does not show great resistance to chloride-ion penetration.
基金financial supports from the National Natural Science Foundation of China(Nos.51875041,51875042)。
文摘A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction.The results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains occurs.The content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μm.Both TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-phase.However,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in microhardness.The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.
基金Project(2007CB613704)supported by the National Basic Research Program of ChinaProject(50874100)supported by the National Natural Science Foundation of China
文摘The microstructures and mechanical properties of Mg-8Li and Mg-8Li-2Al-2RE alloy sheets were evaluated after cold rolling.Both alloys contain α-phase and β-phase which consists of a solid solution of Mg in BCC Li.The proportion ofβ-phase in both alloys is approximately 60%.Theα-phase andβ-phase are elongated approximately parallel to the rolling direction and there is no sign of recrystallization even after being annealed at 200℃for 1 h.The yield strength of Mg-8Li-2Al-2RE sheets is about 165 MPa with elongation of 35%along rolling direction,while the yield strength is about 187 MPa with elongation of 21%along the direction titled 45ü to rolling direction.Theα-phase in both alloys exhibits basal texture,and the intensity of basal texture in Mg-8Li is larger than that in Mg-8Li-2Al-2RE.However,theβ-phase shows(100)texture,and the intensity of(100)texture in Mg-8Li is twice of that in Mg-8Li-2Al-2RE.It could be attributed to the existence of RE-containing particles in Mg-8Li-2Al-2RE.
基金Supported by the National Basic Research Program of China(973 Program:2012CB720500)the National Supporting Research Program of China(Grant2013BAA03B01)+2 种基金the National Natural Science Foundation of China(21176178)the China Scholarship Council(201506250011)the China Postdoctoral Science Foundation(2017M620587)
文摘The focus of this paper is to investigate different control structures(single-loop PI control) for a dividing wall(Petlyuk) column for separating ethanol, n-propanol and n-butanol. Four control structures are studied. All the results are simulations based on Aspen Plus. Control structure 1(CS1) is stabilizing control structure with only temperature controllers. CS2, CS3 and CS4, containing also composition controllers, are introduced to reduce the steady state composition deviations. CS2 adds a distillate composition controller(CCDB) on top of CS1. CS3 is much more complicated with three temperature-composition cascade controllers and in addition a selector to the reboiler duty to control the maximum controller output of light impurity composition control in side stream and bottom impurity control in the prefractionator. CS4 adds another high selector to control the light impurity in the sidestream. Surprisingly, when considering the dynamic and even steady state performance of the proposed control structures, CS1 proves to be the best control structure to handle feed disturbances inserted into the three-product Petlyuk column.
基金financially supported by the National Key R&D Program of China (No.2018YFA0707300)the Natural Science Foundation of Shanxi Province,China (No.201801D221131)+2 种基金the National Natural Science Foundation of China (Nos.51905372,51904206,51805359,52075359)Shanxi Province Science and Technology Major Project,China (No.20181102011)China Postdoctoral Science Foundation (No.2020M670705)。
文摘Ti/Cu/Ti laminated composites were fabricated by corrugated rolling(CR) and flat rolling(FR) method.Microstructure and mechanical properties of CR and FR laminated composites were investigated by scanning electron microscopy, numerical simulation methods, peel and tensile examinations. The effect of CR and FR was comparatively analyzed. The results showed that the CR and FR laminated composites exhibited different effective plastic strain distributions of the Ti layer and Cu layer at the interface. The recrystallization texture, prismatic texture and pyramidal texture were developed in the Ti layer by CR, while the R-Goss texture and shear texture were developed in the Cu layer by CR. The typical deformation texture components were developed in the Ti layer and Cu layer of FR laminated composites. The CR laminated composites had higher bond strength, tensile strength and ductility.
文摘Middle East and North Africa (MENA) has been experiencing a unique demographic transition in the world especially after September 11, whilst, its social, political and economic structures have considerably remained inflexible and can hardly meet the increasing demands of employment among the youth whose expectations are raised through expansion in education. In spite of various common causes for the Arab uprisings, the paper spotlights the "Youth role" and its regarded issues of "Youth Bulge", "Education" and "Unemployment" with a glimpse to the overturned regimes of "Tunisia, Egypt, Libya, and Yemen". According to published statistics these countries are among the countries with the highest rate of youth as working age population in MENA. Therefore, the paper is to present the importance and impact of youth as a social parameter in challenging political structure of the countries in the MENA and leading to topple their political systems. Thus, the paper reasons the MENA political upheavals, in general, and the mentioned countries' uprisings, in particular, can not be well understood disregarding to natural tensions between economic, population structures, and political demographic challenges. This is to be done drawing on data from different international institutions. The intervened variables such as "ethnicity, race, religion and sexuality" and international parameters have not been considered.
基金the National Natural Science Founda-tion of China (No. 10472084)
文摘Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions was analyzed. The resultant forces and velocities of the laminates were calculated, and the structural intensity was evaluated. The SI streamlines of carbon fiber reinforced epoxy composite laminates and the steel plates were discussed. The results show that the SI streamlines of the graphite/epoxy laminates are different from that of the steel plates, and the SI streamlines are influenced by the boundaries, the stacking sequence of the composite laminates. The change of the historical central displacement of the graphite/epoxy laminates is fasten than that of the steel plates.
文摘An optimal control procedure is developed for the front and rear wheels of a three-axle vehicle moving on a complex typical road based on model following variable structure control strategy. The actual vehicle may be considered as an uncertain system. Cornering stiffness of front and rear wheels and external disturbances are varied in a limited range. The model-following variable structure control method is used to control both front and rear wheels steering operations of the vehicle, so that steering responses of the vehicle follow from those of the reference model. By numerical results obtained from computer simulation, it is demonstrated that the control system model can cope with the effects of parameter perturbations and outside disturbances.
文摘By inserting the variable of the exactness of corporate valuation into the classic model of Contract Theory, this paper, on the bases of the interaction of the variables of the veraciousness of corporate valuation, managerial incentives and operational risks, explores the deep-seated reasons for changes in corporate structures, and draws the conclusion that the divestment of the subsidiary is beneficial to shareholders when the parent corporate is undervalued and that the relation between the parent and the subsidiary is disordered, or vice versa. This conclusion is consistent with the motives of many divestiture cases in reality.
文摘This paper considers accounting regulation research from a structuration and cultural perspective. Therefore, accounting regulation research spans over three spheres of enquiry: (1) an accounting focus of standard-setting; (2) a cultural analysis in an empirical context; and (3) the use of a research methodology drawn from Anthony Giddens' structuration theory. In such approach, accounting regulation research analyzes the accounting regulation actors drawing upon the cultures in their standard-setting actions and interactions, referring to Giddens' three structural properties of meaning, power, and morality. The integration of these three spheres of enquiry is not entirely original. A few prior studies have similar combinations: Although they stress the uses and consequences of accounting systems in producing and reproducing organizational culture and negotiating meaning at the organizational level, this paper chooses the research approach of contextual analysis of accounting systems at more macro-societal and cultural levels. This different research interest and design provides this paper with its distinguishable characteristic from the prior similar studies.
基金Project(2009ZM0296) supported by the Fundamental Research Funds for the Central Universities in China
文摘Abstract: An alloy steel/alumina composite was successfully fabricated by pressureless infiltration of X10CrNil8-8 steel melt on 30% (mass fraction) Ni-containing alumina based composite ceramic (Ni/Al2O3) at 1 600 ℃. The infiltration quality and interfacial bonding behavior were investigated by SEM, EDS, XRD and tensile tests. The results show that there is an obvious interfacial reaction layer between the alloying steel and the Ni/Al2O3 composite ceramic. The interfacial reactive products are (FexAly)3O4 intermetallic phase and (AlxCry)2O3 solid solution. The interracial bonding strength is as high as about 67.5 MPa. The bonding mechanism of X10CrNi 18-8 steel with the composite ceramic is that Ni inside the ceramic bodies dissolves into the alloy melt and transforms into liquid channels, consequently inducing the steel melt infiltrating and filling in the pores and the liquid channels. Moreover, the metallurgical bonding and interfacial reactive bonding also play a key role on the stability of the bonding interface.
文摘An economic topology can have many uses to the academician, student and practitioner. Refining a topology of economic systems helps to bring together seemingly disparate characteristics and to point out potential long run trends. The progression of economic systems over time and also brief explanations of each system are given. We argue that most modem economic systems have some remnants of earlier forms, that is, most economies today are some mixture of what might be considered pure systems. Measurable characteristics to identify a particular system are developed that allows progress to or from a particular classification to be charted for individual countries.
基金Project(2011CB706605)supported by the National Basic Research Program of ChinaProject(2011CDA12)supported by the Innovative Research Groups of the Natural Science Foundation of Hubei Province,ChinaProjects(2012-Ia-017,2013-IV-014)supported by the Fundamental Research Funds for the Central Universities,China
文摘Pre-heat treatment is a vital step before cold ring rolling and it has significant effect on the microstructure and mechanical properties of rolled rings.The 100Cr6 steel rings were subjected to pre-heat treatment and subsequent cold rolling process.Scanning electron microscopy and tensile tests were applied to investigate microstructure characteristic and mechanical property variations of 100Cr6 steel rings undergoing different pre-heat treatings.The results indicate that the average diameter of carbide particles,the tensile strength and hardness increase,while the elongation decreases with the decrease of cooling rate.The cooling rate has minor effect on the yield strength of sample.After cold ring rolling,the ferrite matrix shows a clear direction along the rolling direction.The distribution of cementite is more homogeneous and the cementite particles are finer.Meanwhile,the hardness of the rolled ring is higher than that before rolling.
文摘This paper is on control system design for visual based indoor inspection by the model helicopters. For the indoor inspection system for large structures, there are some cases where it is difficult for htunans to work with. This paper introduces indoor inspection helicopter system with only inspection camera and prism for position sensing as payload. The control system is designed to help the operator of the inspection system to control the helicopter to designated position without much practice. The cases of the control by experienced and novice operators are compared and results show that the system has feasibility for indoor inspection system to be used by any kind of users.