The Fabry–Perot(FP) resonant cavity is widely used in laser and spectroscopic measurements due to its unique interference transfer function(ITF). In the ideal case of parallel incident light, the ITF of the FP resona...The Fabry–Perot(FP) resonant cavity is widely used in laser and spectroscopic measurements due to its unique interference transfer function(ITF). In the ideal case of parallel incident light, the ITF of the FP resonant cavity can be expressed by the Airy function. However, in reality, it is difficult to achieve perfect parallelism with collimated beams. In this article, a theoretical model is established for non-parallel light incidence, which assumes that the non-parallel incident light is a cone-shaped beam, and the cone angle is used to quantify the non-parallelism of the beam. The transmittance function of the FP resonant cavity under non-parallel light incidence is derived. The accuracy of the model is experimentally verified. Based on this model, the effects of divergence angle, tilt angle and FP cavity parameters(reflectivity, cavity length)on the ITF are studied. The reasons for the decrease in peak value, broadening and asymmetry of the interference peak under non-parallel light incidence are explained. It is suggested that a fine balance between the interference peak and the collimation effect of the incident light should be considered in the design and application of FP resonant cavities, especially for tilted applications such as angle-scanned spectroscopy. The research results of this article have certain significance for the design and application of FP resonant cavities.展开更多
The metal transfer mode of electron beam welding (EBW) with filler wire was studied experimentally. The spatial position between the electron beam and the filler wire was defined. Basing on the charge coupled device...The metal transfer mode of electron beam welding (EBW) with filler wire was studied experimentally. The spatial position between the electron beam and the filler wire was defined. Basing on the charge coupled device (CCD) visual sensing system, the metal transfer mode of filler wire was investigated. The results showed that there were five transfer modes during EBW process due to different wire feed rates and spatial positions between beam and filler wire, such as short-circuiting mode, molten metal bridge mode, small droplet mode, big droplet mode and mixed mode. By comparing the weld appearance of different transfer modes, the molten metal bridge transfer was proved to be the best transfer mode.展开更多
Under three-dimensional plane geometrical constraints ( X,Y,θ ), with two asymmetric achromatic sections, the combined three-section structural FODO-like magnet lattice design is adopted and finely optimized in the S...Under three-dimensional plane geometrical constraints ( X,Y,θ ), with two asymmetric achromatic sections, the combined three-section structural FODO-like magnet lattice design is adopted and finely optimized in the SSRF electron-beam transfer lines. The magnet lattice has high flexibility and robustness, and the Courant–Snyder parameters can be easily adjusted within a wide range to meet the requirements of transmission and injection for different operation modes of the linear accelerator, booster synchrotron, and storage ring. In this article, the main parameters of the linear optics design of the SSRF electron-beam transfer lines are described, involving the physical design criteria, the total geometrical layout, the magnet lattice, and the beam Courant–Snyder parameters matching. The studies of the variant beam dynamic simulation program calculations show that the design purpose of the efficient beam transmission and injection will be basically achieved.展开更多
Compliant mechanisms with curved flexure hinges/beams have potential advantages of small spaces,low stress levels,and flexible design parameters,which have attracted considerable attention in precision engineering,met...Compliant mechanisms with curved flexure hinges/beams have potential advantages of small spaces,low stress levels,and flexible design parameters,which have attracted considerable attention in precision engineering,metamaterials,robotics,and so forth.However,serial-parallel configurations with curved flexure hinges/beams often lead to a complicated parametric design.Here,the transfer matrix method is enabled for analysis of both the kinetostatics and dynamics of general serial-parallel compliant mechanisms without deriving laborious formulas or combining other modeling methods.Consequently,serial-parallel compliant mechanisms with curved flexure hinges/beams can be modeled in a straightforward manner based on a single transfer matrix of Timoshenko straight beams using a step-by-step procedure.Theoretical and numerical validations on two customized XY nanopositioners comprised of straight and corrugated flexure units confirm the concise modeling process and high prediction accuracy of the presented approach.In conclusion,the present study provides an enhanced transfer matrix modeling approach to streamline the kinetostatic and dynamic analyses of general serial-parallel compliant mechanisms and beam structures,including curved flexure hinges and irregular-shaped rigid bodies.展开更多
Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and us...Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections.展开更多
A digital transfer function measurement system has been embedded in the low-level radio frequency (LLRF) system of the storage ring of the Shanghai Synchrotron Radiation Facility. The measurement results indicate that...A digital transfer function measurement system has been embedded in the low-level radio frequency (LLRF) system of the storage ring of the Shanghai Synchrotron Radiation Facility. The measurement results indicate that the decreased control accuracy at high current is primarily owing to ripples from the high-voltage power supply, the transient beam loading effect, and the digital aliasing effect. The current LLRF algorithm is not able to suppress these disturbances.展开更多
Low-energy ion beam implantation (10 - 200 keV) has been proved to have a wide range of biological effects and is broadly used in the breeding of crops and micro-organisms.To understand its mechanisms better and fac...Low-energy ion beam implantation (10 - 200 keV) has been proved to have a wide range of biological effects and is broadly used in the breeding of crops and micro-organisms.To understand its mechanisms better and facilitate its applications, the developments in the bioeffects of low energy ion beam implantation in the past twenty years are summarized in this paper.展开更多
A three-dimensional mathematical model using volume-of-fluid method is developed to investigate the heat transfer, fluid flow and keyhole dynamics during electron beam welding of 2219 aluminum alloy plate. In the mode...A three-dimensional mathematical model using volume-of-fluid method is developed to investigate the heat transfer, fluid flow and keyhole dynamics during electron beam welding of 2219 aluminum alloy plate. In the model, an adaptive heat source is employed to simulate the heating process of electron beam. Fluid flow is mainly driven by surface tension, thermo-capillary force, recoil pressure, hydrostatic pressure and thermal buoyancy. The thermal-fluid transport behaviors of welding pool during the drilling and backfilling stages of keyhole and the formation reason of the nail-shaped weld with an arc crater are systematically analyzed. Finally, all calculation results are validated by experiments and show good agreements.展开更多
A multi-objective optimization of non-uniform beams is presented for minimum radiated sound power and weight. The transfer matrix method is used to compute the structural and acoustic responses of a non-uniform beam a...A multi-objective optimization of non-uniform beams is presented for minimum radiated sound power and weight. The transfer matrix method is used to compute the structural and acoustic responses of a non-uniform beam accurately and efficiently. The multi-objective particle swarm optimization technique is applied to search the Pareto optimal solutions that represent various compromises between weight and sound radiation. Several constraints are imposed, which substantially reduce the volume fraction of feasible solutions in the design space. Two nonuniform beams with different boundary conditions are studied to demonstrate the multi-objective optimal designs of the structure.展开更多
Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical properties.This study aims to explore t...Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical properties.This study aims to explore the dynamic behaviors of an FGM stepped beam with different boundary conditions based on an efficient solving method.Under the assumptions of the Euler-Bernoulli beam theory,the governing differential equations of an individual FGM beam are derived with Hamilton’s principle and decoupled via the separation-of-variable approach.Then,the free and forced vibrations of the FGM stepped beam are solved with the transfer matrix method(TMM).Two models,i.e.,a three-level FGM stepped beam and a five-level FGM stepped beam,are considered,and their natural frequencies and mode shapes are presented.To demonstrate the validity of the method in this paper,the simulation results by ABAQUS are also given.On this basis,the detailed parametric analyses on the frequencies and dynamic responses of the three-level FGM stepped beam are carried out.The results show the accuracy and efficiency of the TMM.展开更多
The propagation of coupled flexural-torsional vibration in the periodic beam including warping effect is investigated with the transfer matrix theory. The band structures of the periodic beam, both including warping e...The propagation of coupled flexural-torsional vibration in the periodic beam including warping effect is investigated with the transfer matrix theory. The band structures of the periodic beam, both including warping effect and ignoring warping effect, are obtained. The frequency response function of the finite periodic beams is simulated with finite element method, which shows large vibration attenuation in the frequency range of the gap as expected. The effect of warping stiffness on the band structure is studied and it is concluded that substantial error can be produced in high frequency range if the effect is ignored. The result including warping effect agrees quite well with the simulated result.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.U19A2044)the National Natural Science Foundation of China (Grant No.41975037)the Key Technologies Research and Development Program of Anhui Province (Grant No.202004i07020013)。
文摘The Fabry–Perot(FP) resonant cavity is widely used in laser and spectroscopic measurements due to its unique interference transfer function(ITF). In the ideal case of parallel incident light, the ITF of the FP resonant cavity can be expressed by the Airy function. However, in reality, it is difficult to achieve perfect parallelism with collimated beams. In this article, a theoretical model is established for non-parallel light incidence, which assumes that the non-parallel incident light is a cone-shaped beam, and the cone angle is used to quantify the non-parallelism of the beam. The transmittance function of the FP resonant cavity under non-parallel light incidence is derived. The accuracy of the model is experimentally verified. Based on this model, the effects of divergence angle, tilt angle and FP cavity parameters(reflectivity, cavity length)on the ITF are studied. The reasons for the decrease in peak value, broadening and asymmetry of the interference peak under non-parallel light incidence are explained. It is suggested that a fine balance between the interference peak and the collimation effect of the incident light should be considered in the design and application of FP resonant cavities, especially for tilted applications such as angle-scanned spectroscopy. The research results of this article have certain significance for the design and application of FP resonant cavities.
文摘The metal transfer mode of electron beam welding (EBW) with filler wire was studied experimentally. The spatial position between the electron beam and the filler wire was defined. Basing on the charge coupled device (CCD) visual sensing system, the metal transfer mode of filler wire was investigated. The results showed that there were five transfer modes during EBW process due to different wire feed rates and spatial positions between beam and filler wire, such as short-circuiting mode, molten metal bridge mode, small droplet mode, big droplet mode and mixed mode. By comparing the weld appearance of different transfer modes, the molten metal bridge transfer was proved to be the best transfer mode.
基金Supported by National Important Scientific Project "Shanghai Synchrotron Radiation Facility".
文摘Under three-dimensional plane geometrical constraints ( X,Y,θ ), with two asymmetric achromatic sections, the combined three-section structural FODO-like magnet lattice design is adopted and finely optimized in the SSRF electron-beam transfer lines. The magnet lattice has high flexibility and robustness, and the Courant–Snyder parameters can be easily adjusted within a wide range to meet the requirements of transmission and injection for different operation modes of the linear accelerator, booster synchrotron, and storage ring. In this article, the main parameters of the linear optics design of the SSRF electron-beam transfer lines are described, involving the physical design criteria, the total geometrical layout, the magnet lattice, and the beam Courant–Snyder parameters matching. The studies of the variant beam dynamic simulation program calculations show that the design purpose of the efficient beam transmission and injection will be basically achieved.
基金funded by the National Natural Science Foundation of China(Grant/Award Numbers:52075179 and 52130508)Jiangsu Policy Guidance Program(International Science and Technology Cooperation)the Belt and Road Initiative Innovative Cooperation Projects:BZ2021016.
文摘Compliant mechanisms with curved flexure hinges/beams have potential advantages of small spaces,low stress levels,and flexible design parameters,which have attracted considerable attention in precision engineering,metamaterials,robotics,and so forth.However,serial-parallel configurations with curved flexure hinges/beams often lead to a complicated parametric design.Here,the transfer matrix method is enabled for analysis of both the kinetostatics and dynamics of general serial-parallel compliant mechanisms without deriving laborious formulas or combining other modeling methods.Consequently,serial-parallel compliant mechanisms with curved flexure hinges/beams can be modeled in a straightforward manner based on a single transfer matrix of Timoshenko straight beams using a step-by-step procedure.Theoretical and numerical validations on two customized XY nanopositioners comprised of straight and corrugated flexure units confirm the concise modeling process and high prediction accuracy of the presented approach.In conclusion,the present study provides an enhanced transfer matrix modeling approach to streamline the kinetostatic and dynamic analyses of general serial-parallel compliant mechanisms and beam structures,including curved flexure hinges and irregular-shaped rigid bodies.
基金Supported by National Natural Science Foundation of China(No.51268054)Natural Science Foundation of Tianjin(No.13JCQNJC07300)the foundation of Key Laboratory of Coast Civil Structure Safety(Tianjin University),Ministry of Education of China(No.2011-1)
文摘Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections.
文摘A digital transfer function measurement system has been embedded in the low-level radio frequency (LLRF) system of the storage ring of the Shanghai Synchrotron Radiation Facility. The measurement results indicate that the decreased control accuracy at high current is primarily owing to ripples from the high-voltage power supply, the transient beam loading effect, and the digital aliasing effect. The current LLRF algorithm is not able to suppress these disturbances.
文摘Low-energy ion beam implantation (10 - 200 keV) has been proved to have a wide range of biological effects and is broadly used in the breeding of crops and micro-organisms.To understand its mechanisms better and facilitate its applications, the developments in the bioeffects of low energy ion beam implantation in the past twenty years are summarized in this paper.
文摘A three-dimensional mathematical model using volume-of-fluid method is developed to investigate the heat transfer, fluid flow and keyhole dynamics during electron beam welding of 2219 aluminum alloy plate. In the model, an adaptive heat source is employed to simulate the heating process of electron beam. Fluid flow is mainly driven by surface tension, thermo-capillary force, recoil pressure, hydrostatic pressure and thermal buoyancy. The thermal-fluid transport behaviors of welding pool during the drilling and backfilling stages of keyhole and the formation reason of the nail-shaped weld with an arc crater are systematically analyzed. Finally, all calculation results are validated by experiments and show good agreements.
基金supported by the National Natural Science Foundation of China (No. 51606180)
文摘A multi-objective optimization of non-uniform beams is presented for minimum radiated sound power and weight. The transfer matrix method is used to compute the structural and acoustic responses of a non-uniform beam accurately and efficiently. The multi-objective particle swarm optimization technique is applied to search the Pareto optimal solutions that represent various compromises between weight and sound radiation. Several constraints are imposed, which substantially reduce the volume fraction of feasible solutions in the design space. Two nonuniform beams with different boundary conditions are studied to demonstrate the multi-objective optimal designs of the structure.
基金the National Natural Science Foundation of China(Nos.12302007,12372006,and 12202109)the Specific Research Project of Guangxi for Research Bases and Talents(No.AD23026051)。
文摘Functionally graded materials(FGMs)are a novel class of composite materials that have attracted significant attention in the field of engineering due to their unique mechanical properties.This study aims to explore the dynamic behaviors of an FGM stepped beam with different boundary conditions based on an efficient solving method.Under the assumptions of the Euler-Bernoulli beam theory,the governing differential equations of an individual FGM beam are derived with Hamilton’s principle and decoupled via the separation-of-variable approach.Then,the free and forced vibrations of the FGM stepped beam are solved with the transfer matrix method(TMM).Two models,i.e.,a three-level FGM stepped beam and a five-level FGM stepped beam,are considered,and their natural frequencies and mode shapes are presented.To demonstrate the validity of the method in this paper,the simulation results by ABAQUS are also given.On this basis,the detailed parametric analyses on the frequencies and dynamic responses of the three-level FGM stepped beam are carried out.The results show the accuracy and efficiency of the TMM.
基金Project supported by the State Key Development Program for Basic Research of China (Grant No 51307)the National Natural Science Foundation of China (Grant No 50575222)
文摘The propagation of coupled flexural-torsional vibration in the periodic beam including warping effect is investigated with the transfer matrix theory. The band structures of the periodic beam, both including warping effect and ignoring warping effect, are obtained. The frequency response function of the finite periodic beams is simulated with finite element method, which shows large vibration attenuation in the frequency range of the gap as expected. The effect of warping stiffness on the band structure is studied and it is concluded that substantial error can be produced in high frequency range if the effect is ignored. The result including warping effect agrees quite well with the simulated result.