In view of the flaws of component-based software （CBS） reliability modeling and analysis, the low recognition degree of debugging process, too many assumptions and difficulties in obtaining the solution, a CBS relia...In view of the flaws of component-based software （CBS） reliability modeling and analysis, the low recognition degree of debugging process, too many assumptions and difficulties in obtaining the solution, a CBS reliability simulation process is presented incorporating the imperfect debugging and the limitation of debugging resources. Considering the effect of imperfect debugging on fault detec- tion and correction process, a CBS integration testing model is sketched by multi-queue muhichannel and finite server queuing model （MMFSQM）. Compared with the analytical method based on pa- rameters and other nonparametric approaches, the simulation approach can relax more of the usual reliability modeling assumptions and effectively expound integration testing process of CBS. Then, CBS reliability process simulation procedure is developed accordingly. The proposed simulation ap- proach is validated to be sound and effective by simulation experiment studies and analysis.展开更多
The evolution of microstructure on aging of an （α＋β） titanium alloy （Ti-5A1-5Mo-5V-1Cr-1Fe） in the β and （α＋β） solution-treated and quenched conditions was investigated, The presence of very fine to phase...The evolution of microstructure on aging of an （α＋β） titanium alloy （Ti-5A1-5Mo-5V-1Cr-1Fe） in the β and （α＋β） solution-treated and quenched conditions was investigated, The presence of very fine to phase was detected by electron diffraction for samples aged below 400 ℃. The fine a aggregates are uniformly formed within fl grains by nucleating at the to particles or β/ω interfaces. At higher temperature, the formation of to phase is avoided and the a lamellae are precipitated at the preferred site of grain boundary and then within the matrix. The highest hardness values are found when the alloys are aged at 450 ℃ for fl condition and 350 ℃ for （α＋β） condition.展开更多
Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed dow...Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa. The model parameters of Bo and 9 were estimated with the least square method in the time domain. As liquid flow rate was increased, the liquid axial mixing decreased. Under our experimental conditions, the effect of pressure on Bo number on single liquid phase was negligible, and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.展开更多
In South Africa, the nuclear forensics approach and its functions hosted and managed by Necsa, in support of any nuclear security investigations, start from the incident scene when the nuclear or radioactive material ...In South Africa, the nuclear forensics approach and its functions hosted and managed by Necsa, in support of any nuclear security investigations, start from the incident scene when the nuclear or radioactive material （that is out of regulatory control） is being handled and handed over to Necsa Emergency Control Centre by the South African law enforcement agencies in the presence of NOMS Department official. The main objective of this approach is to increase the credibility status of the chain of custody on the handling of the material during incident （crime） scene management process （for both nuclear forensics and traditional forensic evidence collection） and its transportation from the scene to the suitable storage facility at Necsa. Aspects to be looked into during the response process include interactions between law enforcement agencies, Necsa relevant departments and the National Nuclear Regulator of South Africa. This paper focuses on the entire whole response process and associated prior arrangements, in order to show and provide a set of requirements attached to the material, the scope of critical relevant technical and law enforcement information that to be acquired by all parties involving and participating in the nuclear/radiological incident or event response process before the material is authorized for storage at a suitably qualified Necsa＇s nuclear forensics, which is dedicated storage facility on Pelindaba site.展开更多
According to the characteristics of flexible manufacturing systems, the article describes the equipment components and hardware architecture of flexible manufacturing systems in school. Taking welding assemble process...According to the characteristics of flexible manufacturing systems, the article describes the equipment components and hardware architecture of flexible manufacturing systems in school. Taking welding assemble process as an example to elaborate production process automation, the paper put forward a flexible manufacaxring system combined with laboratory equipment and various grades, professional knowledge and teaching characteristics and differentiated teaching programs, the creation of the laboratory project was planned and implemented to specific engineering training programs, so that students has been expanded in the depth of expertise and breadth, experimental skills and innovation capacity has been improved, the teaching effect has also been significantly improved..展开更多
During the evolution of the binary system, many physical processes occur, which can influence the orbital angular velocity and the spin angular velocities of the two components, and influence the non-synchronous or sy...During the evolution of the binary system, many physical processes occur, which can influence the orbital angular velocity and the spin angular velocities of the two components, and influence the non-synchronous or synchronous rotation of the system. These processes include the transfer of masses and angular momentums between the component stars, the loss of mass and angular momentum via stellar winds, and the deformation of the structure of component stars. A study of these processes indicates that they are closely related to the combined effects of tide and rotation. This means, to study the synchronous or non-synchronous rotation of binary systems, one has to consider the contributions of different physical processes simultaneously, instead of the tidal effect alone. A way to know whether the rotation of a binary system is synchronous or non-synchronous is to calculate the orbital angular velocity and the spin angular velocities of the component stars. If all of these angular velocities are equal, the rotation of the system is synchronous. If not, the rotation of the system is non-synchronous. For this aim, a series of equations are developed to calculate the orbital and spin angular velocities. The evolutionary calculation of a binary system with masses of 10M~ ＋ 6Me shows that the transfer of masses and angular momentums between the two components, and the deformation of the components structure in the semidetached or in the contact phase can change the rotation of the system from synchronous into non-synchronous rotation.展开更多
Slender chiral filaments are ubiquitous in both artificial and biological materials.Due to their chiral microstructures,chiral filaments usually exhibit favorable properties such as superior elasticity and unusual str...Slender chiral filaments are ubiquitous in both artificial and biological materials.Due to their chiral microstructures,chiral filaments usually exhibit favorable properties such as superior elasticity and unusual stretch-twist coupling deformation.However,how these chiral microstructures affect the elastic behavior of filaments remains unclear.In this paper,a refined Cosserat rod model with misfit or mismatching of chirality induced by inhomogeneous arrangement of chiral microstructures incorporated is developed.Using the refined rod model,the force-displacement relationships and variation of structural chirality during the tensile processes of two typical helical structures,i.e.,single-strand helix and double-strand helix,are investigated.The results show that the misfit of chirality can lead to a bend-twist deformation with a high coupling degree,which makes the rod much“soft”when stretched.The chiral filaments undergo an unusual twist when stretched,corresponding to an obviously nonlinear variation of structural chirality.The work suggests that the misfit of chirality can be used to tune the elastic behavior of chiral filaments,which is helpful in guiding the design of flexible actuators and soft devices.展开更多
基金Supported by the National High Technology Research and Development Program of China(No.2008AA01A201)the National Nature Science Foundation of China(No.60503015,90818016)
文摘In view of the flaws of component-based software （CBS） reliability modeling and analysis, the low recognition degree of debugging process, too many assumptions and difficulties in obtaining the solution, a CBS reliability simulation process is presented incorporating the imperfect debugging and the limitation of debugging resources. Considering the effect of imperfect debugging on fault detec- tion and correction process, a CBS integration testing model is sketched by multi-queue muhichannel and finite server queuing model （MMFSQM）. Compared with the analytical method based on pa- rameters and other nonparametric approaches, the simulation approach can relax more of the usual reliability modeling assumptions and effectively expound integration testing process of CBS. Then, CBS reliability process simulation procedure is developed accordingly. The proposed simulation ap- proach is validated to be sound and effective by simulation experiment studies and analysis.
基金Project (50634030) supported by the National Natural Science Foundation of ChinaProject (2007DS04014) supported by the Program of Science and Technology of Shandong Province,ChinaProject supported by the Open Research Fund from the State Key Laboratory of Rolling and Automation,Northeastern University, China
文摘The evolution of microstructure on aging of an （α＋β） titanium alloy （Ti-5A1-5Mo-5V-1Cr-1Fe） in the β and （α＋β） solution-treated and quenched conditions was investigated, The presence of very fine to phase was detected by electron diffraction for samples aged below 400 ℃. The fine a aggregates are uniformly formed within fl grains by nucleating at the to particles or β/ω interfaces. At higher temperature, the formation of to phase is avoided and the a lamellae are precipitated at the preferred site of grain boundary and then within the matrix. The highest hardness values are found when the alloys are aged at 450 ℃ for fl condition and 350 ℃ for （α＋β） condition.
基金Supported by the National Natural Science Foundation of China (No. 20136010).
文摘Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m, in which the structured packing, Mellapak 350Y, was installed. Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa. The model parameters of Bo and 9 were estimated with the least square method in the time domain. As liquid flow rate was increased, the liquid axial mixing decreased. Under our experimental conditions, the effect of pressure on Bo number on single liquid phase was negligible, and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.
文摘In South Africa, the nuclear forensics approach and its functions hosted and managed by Necsa, in support of any nuclear security investigations, start from the incident scene when the nuclear or radioactive material （that is out of regulatory control） is being handled and handed over to Necsa Emergency Control Centre by the South African law enforcement agencies in the presence of NOMS Department official. The main objective of this approach is to increase the credibility status of the chain of custody on the handling of the material during incident （crime） scene management process （for both nuclear forensics and traditional forensic evidence collection） and its transportation from the scene to the suitable storage facility at Necsa. Aspects to be looked into during the response process include interactions between law enforcement agencies, Necsa relevant departments and the National Nuclear Regulator of South Africa. This paper focuses on the entire whole response process and associated prior arrangements, in order to show and provide a set of requirements attached to the material, the scope of critical relevant technical and law enforcement information that to be acquired by all parties involving and participating in the nuclear/radiological incident or event response process before the material is authorized for storage at a suitably qualified Necsa＇s nuclear forensics, which is dedicated storage facility on Pelindaba site.
文摘According to the characteristics of flexible manufacturing systems, the article describes the equipment components and hardware architecture of flexible manufacturing systems in school. Taking welding assemble process as an example to elaborate production process automation, the paper put forward a flexible manufacaxring system combined with laboratory equipment and various grades, professional knowledge and teaching characteristics and differentiated teaching programs, the creation of the laboratory project was planned and implemented to specific engineering training programs, so that students has been expanded in the depth of expertise and breadth, experimental skills and innovation capacity has been improved, the teaching effect has also been significantly improved..
基金supported by the National Natural Science Foundation of China(Grant No.10933002)
文摘During the evolution of the binary system, many physical processes occur, which can influence the orbital angular velocity and the spin angular velocities of the two components, and influence the non-synchronous or synchronous rotation of the system. These processes include the transfer of masses and angular momentums between the component stars, the loss of mass and angular momentum via stellar winds, and the deformation of the structure of component stars. A study of these processes indicates that they are closely related to the combined effects of tide and rotation. This means, to study the synchronous or non-synchronous rotation of binary systems, one has to consider the contributions of different physical processes simultaneously, instead of the tidal effect alone. A way to know whether the rotation of a binary system is synchronous or non-synchronous is to calculate the orbital angular velocity and the spin angular velocities of the component stars. If all of these angular velocities are equal, the rotation of the system is synchronous. If not, the rotation of the system is non-synchronous. For this aim, a series of equations are developed to calculate the orbital and spin angular velocities. The evolutionary calculation of a binary system with masses of 10M~ ＋ 6Me shows that the transfer of masses and angular momentums between the two components, and the deformation of the components structure in the semidetached or in the contact phase can change the rotation of the system from synchronous into non-synchronous rotation.
基金the National Natural Science Foundation of China(Grant Nos.12020101001,12021002,11872273,and 11890680)Tianjin Research Program of Application Foundation and Advanced Technology(Grant No.19JCYBJC19300).
文摘Slender chiral filaments are ubiquitous in both artificial and biological materials.Due to their chiral microstructures,chiral filaments usually exhibit favorable properties such as superior elasticity and unusual stretch-twist coupling deformation.However,how these chiral microstructures affect the elastic behavior of filaments remains unclear.In this paper,a refined Cosserat rod model with misfit or mismatching of chirality induced by inhomogeneous arrangement of chiral microstructures incorporated is developed.Using the refined rod model,the force-displacement relationships and variation of structural chirality during the tensile processes of two typical helical structures,i.e.,single-strand helix and double-strand helix,are investigated.The results show that the misfit of chirality can lead to a bend-twist deformation with a high coupling degree,which makes the rod much“soft”when stretched.The chiral filaments undergo an unusual twist when stretched,corresponding to an obviously nonlinear variation of structural chirality.The work suggests that the misfit of chirality can be used to tune the elastic behavior of chiral filaments,which is helpful in guiding the design of flexible actuators and soft devices.
