Aiming at the discontinuous traction on contact elements of roller bearing,new concepts of sub- and micro-element are put forward. In the sub-element and micro-element,traction influence coefficient has been modified,...Aiming at the discontinuous traction on contact elements of roller bearing,new concepts of sub- and micro-element are put forward. In the sub-element and micro-element,traction influence coefficient has been modified, which is calculated by the former boundary elementmethod (BEM) with roller bearing load. Hence, three-dimensional distribution of load on rollerbearing is calculated accurately. In practice, it has been proved that this method has highercalculation accuracy. An effective numerical method is offered for analyzing load characteristics ofroller bearing to improve service longevity of roller bearing and operation efficiency of rollingmill.展开更多
This study describes the details of how to construct a three-dimensional （3D） finite element model of a maxillary first premolar tooth based on micro-CT data acquisition technique, MIMICS soft- ware and ANSYS softwa...This study describes the details of how to construct a three-dimensional （3D） finite element model of a maxillary first premolar tooth based on micro-CT data acquisition technique, MIMICS soft- ware and ANSYS software. The tooth was scanned by micro-CT, in which 1295 slices were obtained and then 648 slices were selected for modeling. The 3D surface mesh models of enamel and dentin were created by MIMICS （STL file）. The solid mesh model was constructed by ANSYS. After the material properties and boundary conditions were set, a loading analysis was performed to demonstrate the ap- plicableness of the resulting model. The first and third principal stresses were then evaluated. The re- suits showed that the number of nodes and elements of the finite element model were 56 618 and 311801, respectively. The geometric form of the model was highly consistent with that of the true tooth, and the deviation between them was ~）.28%. The loading analysis revealed the typical stress patterns in the contour map. The maximum compressive stress existed in the contact points and the maximum tensile stress existed in the deep fissure between the two cusps. It is concluded that by using the micro-CT and highly integrated software, construction of the 3D finite element model with high quality will not be difficult for clinical researchers.展开更多
Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding （LFW） were investigated by us...Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding （LFW） were investigated by using finite element method. The effect of micro-pore defect on the axial shortening of joints during LFW was examined. The x- and y-direction displacements of micro-pore during the LFW process were also studied. In addition, the shape of micro-pore after LFW was observed. The heat conducted from the weld inteace to the specimen interior. The fluctuation range of the temperature curves for the joint with micro-pore is larger than that without micro-pore. Position of micro-pore changes with the change of the friction time. The circular shape of micro-pore becomes oval after welding.展开更多
Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental mic...Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.展开更多
Heterogeneity is an inherent component of rock and may be present in different forms including mineralheterogeneity, geometrical heterogeneity, weak grain boundaries and micro-defects. Microcracks areusually observed ...Heterogeneity is an inherent component of rock and may be present in different forms including mineralheterogeneity, geometrical heterogeneity, weak grain boundaries and micro-defects. Microcracks areusually observed in crystalline rocks in two forms： natural and stress-induced; the amount of stressinducedmicrocracking increases with depth and in-situ stress. Laboratory results indicate that thephysical properties of rocks such as strength, deformability, P-wave velocity and permeability areinfluenced by increase in microcrack intensity. In this study, the finite-discrete element method （FDEM）is used to model microcrack heterogeneity by introducing into a model sample sets of microcracks usingthe proposed micro discrete fracture network （mDFN） approach. The characteristics of the microcracksrequired to create mDFN models are obtained through image analyses of thin sections of Lac du Bonnetgranite adopted from published literature. A suite of two-dimensional laboratory tests including uniaxial,triaxial compression and Brazilian tests is simulated and the results are compared with laboratory data.The FDEM-mDFN models indicate that micro-heterogeneity has a profound influence on both the mechanicalbehavior and resultant fracture pattern. An increase in the microcrack intensity leads to areduction in the strength of the sample and changes the character of the rock strength envelope. Spallingand axial splitting dominate the failure mode at low confinement while shear failure is the dominantfailure mode at high confinement. Numerical results from simulated compression tests show thatmicrocracking reduces the cohesive component of strength alone, and the frictional strength componentremains unaffected. Results from simulated Brazilian tests show that the tensile strength is influenced bythe presence of microcracks, with a reduction in tensile strength as microcrack intensity increases. Theimportance of microcrack heterogeneity in reproducing a bi-linear or S-shape failure envelope and itseffects on the mechanisms leading to spalling damage near an underground opening are also discussed.展开更多
In the classical theory of elasticity,a body is initially modeled as a homogeneous and dense assemblage of constituent ＂material particles＂.The kernel concept of elastic deformation is the displacement of the partic...In the classical theory of elasticity,a body is initially modeled as a homogeneous and dense assemblage of constituent ＂material particles＂.The kernel concept of elastic deformation is the displacement of the particle that associates the current configuration with the reference one.In this paper,we exploit an alternative constituent ＂micro-finite element＂,and use the stretch of the element as the essential quality to recast the theory of elasticity.It should be realized that such a treatment means that the elastic body can be modeled as a finite covering of elements and consequently characterized by a manifold.The recasting of the elasticity theory becomes more feasible for dealing with defects and topological evolution.展开更多
On the basis of the in situ data of DO2, pH, SiO2. PO4-P, NO3-N and NO2-N collected in the north of the East China Sea during 1987-1988, the following points are mainly expounded.1.The inorgonic nutrients are obviousl...On the basis of the in situ data of DO2, pH, SiO2. PO4-P, NO3-N and NO2-N collected in the north of the East China Sea during 1987-1988, the following points are mainly expounded.1.The inorgonic nutrients are obviously affected by continent runoff in the north of the East China Sea. Their distributions are characteristic of its distribution of terrigenous materials.2.There are three transport paths of nutrients from the shelf to the Kuroshio area. The first is mixing-diffusing-advec-tion and upwelling process, the process of biology and biochemistry belongs to the second, and the sinking process is the last one.3.The swing of the Kuroshio axis affectes both the range of the migration of substances through mixing-diffusing-advec-tion process and the upwelling degree of the subsurface Kuroshio water to the shelf.4.Most part of the substances sink as macroparticles to the deep layer before reaching the Kuroshio area.展开更多
AIM To reduce post treatments of kyphoplasty, as a common treatment for osteoporotic vertebrae.METHODS This study suggests a new method for treating vertebrae by setting the hexagonal porous structure instead of the r...AIM To reduce post treatments of kyphoplasty, as a common treatment for osteoporotic vertebrae.METHODS This study suggests a new method for treating vertebrae by setting the hexagonal porous structure instead of the rigid bone cement mass in the kyphoplasty(KP). The KP procedure was performed on the fresh ovine vertebra of the level L1. Micro finite element modeling was performed based on micro computed tomography of ovine trabecular cube. The hexagonal porous structure was set on one cube instead of the bone cement mass. For the implant designing, two geometrical parameters were considered: Spacing diameter and thickness.RESULTS The results of micro finite element analyses indicated the improvement in the mechanical behavior of the vertebra treated by the hexagonal porous structures, as compared to those treated by vertebroplasty(VP) and KP under static loading. The improvement in the mechanical behavior of the vertebra, was observed as 54% decrease in the amount of maximum Von Misses stress(improvement of stress distribution), in trabecular cube with embedded hexagonal structure, as compared to VP and KP. This is comparable to the results of the experimental study already performed; it was shown that the improvement of mechanical behavior of the vertebra was observed as: 83% increase in the range of displacements before getting to the ultimate strength(increasing the toughness) after setting hexagonal pearls inside vertebrae. Both the material and geometry of implant influenced the amount of Von Mises stress in the structure.CONCLUSION The new proposed method can be offered as a substitute for the KP. The implant geometry had a more obvious effect on the amount of Von Mises stress, as compared to the implant material.展开更多
Several approaches to fabricate micro optical elements by use of half tone masks are studied and compared. It is shown that half tone masks employed in filtering image systems can obtain gray patterns with considerabl...Several approaches to fabricate micro optical elements by use of half tone masks are studied and compared. It is shown that half tone masks employed in filtering image systems can obtain gray patterns with considerably high precision, but it is hard to operate from the viewpoint of operation. The method using contacting lithography technology or laser ablation can be easily operated with the cost of reducing fabrication precision and the trouble of choosing appropriate materials. For all of these methods, the coding of half tone masks with corrections for the nonlinear characteristics of coding, imaging and photoresist is recommended.展开更多
The micro-mechanical response of asphalt mixtures was studied using the discrete element method. The discrete element sample of stone mastic asphalt was generated first and the vehicle load was applied to the sample. ...The micro-mechanical response of asphalt mixtures was studied using the discrete element method. The discrete element sample of stone mastic asphalt was generated first and the vehicle load was applied to the sample. A user-written program was coded with the FISH language in PFC3 D to extract the contact forces within the sample and the displacements of the particles. Then, the contact forces within the whole sample, in asphalt mastic, in coarse aggregates and between asphalt mastic and coarse aggregates were investigated. Finally, the movement of the particles in the sample was analyzed. The sample was divided into 15 areas and a figure was drawn to show how the balls move in each area according to the displacements of the balls in each area. The displacements of asphalt mastic balls and coarse aggregates were also analyzed. The experimental results explain how the asphalt mixture bears vehicle load and the potential reasons why the rutting forms from a micro-mechanical view.展开更多
Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher ...Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.展开更多
Coupled thermo-mechanical analysis of two bonded functionally graded materials subjected to thermal loads is conducted in this study with the graded finite element method. The thermal-mechanical properties of the bi-m...Coupled thermo-mechanical analysis of two bonded functionally graded materials subjected to thermal loads is conducted in this study with the graded finite element method. The thermal-mechanical properties of the bi-material interfaces are classified based on discontinuity degrees of their material properties and their derivatives at the interfaces. Numerical results indicate that discontinuity exerts remarkable effect on the temperature profile and stress value at the interface of two bonded functionally-graded materials. Under the thermal flux loading conditions, the stronger the interface discontinuity is, the smaller the heat flux is.展开更多
Vibrational behavior of thermally actuated cantilever micro-beams and their mechanical response at moderately high frequency under a non-harmonic periodic loading is studied in this paper. Two different configurations...Vibrational behavior of thermally actuated cantilever micro-beams and their mechanical response at moderately high frequency under a non-harmonic periodic loading is studied in this paper. Two different configurations are considered: 1) a straight beam with two actuation layers on top and bottom which utilizes the bimorph effect to induce bending;2) a uniform beam with base excitation, where the beam is mounted on an actuator which moves it periodically at its base perpendicular to its axis. Generally, vibrating micro-cantilevers are required to oscillate at a specified frequency. In order to increase the efficiency of the system, and achieve deflections with low power consumption, geometrical features of the beams can be quantified so that the required vibrating frequency matches the natural frequencies of the beam. A parametric modal analysis is conducted on two configurations of micro-cantilever and the first natural frequency of the cantilevers as a function of geometrical parameters is extracted. To evaluate vibrational behavior and thermo-mechanical efficiency of micro-cantilevers as a function of their geometrical parameters and input power, a case study with a specified vibrating frequency is considered. Due to significant complexities in the loading conditions and thermo-mechanical behavior, this task can only be tackled via numerical methods. Selecting the geometrical parameters in order to induce resonance at the nominal frequency, non-linear time-history (transient) thermo-mechanical finite element analysis (using ANSYS) is run on each configuration to study its response to the periodic heating input. Approaches to improve the effectiveness of actuators in each configuration based on their implementation are investigated.展开更多
Content of macro- and microelements in plant and soil was studied after biochar, compost, digestate, lignite, and lignohumate application. Pot experiments were carried out in Phytotron CLF Plant Master （Wertingen, Ge...Content of macro- and microelements in plant and soil was studied after biochar, compost, digestate, lignite, and lignohumate application. Pot experiments were carried out in Phytotron CLF Plant Master （Wertingen, Germany）. As tested plant lettuce （Lactucasativa） was used. Elemental composition was determined by AAS and XRF spectroscopy. Macronutrients content （Ca, Mg, K, and P） was determined by Mehlich III. Total content of carbon and nitrogen were determined by LECO TruSpec CN analyser. Results showed that different exogenous organic amendments statistically significantly influenced macro and micronutrients content in soil and plant. Satisfactory C/N ratio for soil microorganisms was measured only after compost and digestate application. As concerns hazardous elements, no legislation limits were overstepped after application of the tested organic amendments. Bioavailability and their uptake by plants followed the order： Cd 〉 Mn 〉 Zn 〉 Fe.展开更多
基金This project is supported by National Natural Science Foundation of China (No.50205004, No. 50075075).
文摘Aiming at the discontinuous traction on contact elements of roller bearing,new concepts of sub- and micro-element are put forward. In the sub-element and micro-element,traction influence coefficient has been modified, which is calculated by the former boundary elementmethod (BEM) with roller bearing load. Hence, three-dimensional distribution of load on rollerbearing is calculated accurately. In practice, it has been proved that this method has highercalculation accuracy. An effective numerical method is offered for analyzing load characteristics ofroller bearing to improve service longevity of roller bearing and operation efficiency of rollingmill.
文摘This study describes the details of how to construct a three-dimensional （3D） finite element model of a maxillary first premolar tooth based on micro-CT data acquisition technique, MIMICS soft- ware and ANSYS software. The tooth was scanned by micro-CT, in which 1295 slices were obtained and then 648 slices were selected for modeling. The 3D surface mesh models of enamel and dentin were created by MIMICS （STL file）. The solid mesh model was constructed by ANSYS. After the material properties and boundary conditions were set, a loading analysis was performed to demonstrate the ap- plicableness of the resulting model. The first and third principal stresses were then evaluated. The re- suits showed that the number of nodes and elements of the finite element model were 56 618 and 311801, respectively. The geometric form of the model was highly consistent with that of the true tooth, and the deviation between them was ~）.28%. The loading analysis revealed the typical stress patterns in the contour map. The maximum compressive stress existed in the contact points and the maximum tensile stress existed in the deep fissure between the two cusps. It is concluded that by using the micro-CT and highly integrated software, construction of the 3D finite element model with high quality will not be difficult for clinical researchers.
基金The authors would like to appreeiate the National Natural Science Foundation of China （51005180）, the Fok Ying-Tong Educalion Fuundalion for Young Teachers in the Higher Education Institutions of China （131052） , the Fundamental Research Fund of NPU（JC201233） , and the 111 Project of China （B08040）.
文摘Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding （LFW） were investigated by using finite element method. The effect of micro-pore defect on the axial shortening of joints during LFW was examined. The x- and y-direction displacements of micro-pore during the LFW process were also studied. In addition, the shape of micro-pore after LFW was observed. The heat conducted from the weld inteace to the specimen interior. The fluctuation range of the temperature curves for the joint with micro-pore is larger than that without micro-pore. Position of micro-pore changes with the change of the friction time. The circular shape of micro-pore becomes oval after welding.
基金supported by National Natural Science Foundation of China(No.81303218)Beijing Municipal Government for the University Affiliated with the Party Central CommitteeDoctoral Fund of Ministry of Education of China(No.20130013120006)
文摘Laser-induced breakdown spectroscopy （LIBS） was used to decipher the unique multi-elemental characteristics of Juncus effusus L. The spectral fingerprints of Juncus effusus L. were established based on elemental microanalysis via LIBS. Microanalysis and multimode sampling methodologies were designed in this study. The relative standard deviation （RSD） approach was performed to optimize the multi-shot measurements. Taking advantage of the capability with no or minimal sample pre-treatment of LIBS, a thermodynamic chart of four elements （Mg, Ca, Ba, and Na） was created from twelve collection regions. The diagram of elemental distribution on a micro-scale was generated to explore the nature of Juncus effusus L. by LIBS. The results demon- strated that LIBS is a promising technique for rapid elemental microanalysis of heterogeneous samples.
文摘Heterogeneity is an inherent component of rock and may be present in different forms including mineralheterogeneity, geometrical heterogeneity, weak grain boundaries and micro-defects. Microcracks areusually observed in crystalline rocks in two forms： natural and stress-induced; the amount of stressinducedmicrocracking increases with depth and in-situ stress. Laboratory results indicate that thephysical properties of rocks such as strength, deformability, P-wave velocity and permeability areinfluenced by increase in microcrack intensity. In this study, the finite-discrete element method （FDEM）is used to model microcrack heterogeneity by introducing into a model sample sets of microcracks usingthe proposed micro discrete fracture network （mDFN） approach. The characteristics of the microcracksrequired to create mDFN models are obtained through image analyses of thin sections of Lac du Bonnetgranite adopted from published literature. A suite of two-dimensional laboratory tests including uniaxial,triaxial compression and Brazilian tests is simulated and the results are compared with laboratory data.The FDEM-mDFN models indicate that micro-heterogeneity has a profound influence on both the mechanicalbehavior and resultant fracture pattern. An increase in the microcrack intensity leads to areduction in the strength of the sample and changes the character of the rock strength envelope. Spallingand axial splitting dominate the failure mode at low confinement while shear failure is the dominantfailure mode at high confinement. Numerical results from simulated compression tests show thatmicrocracking reduces the cohesive component of strength alone, and the frictional strength componentremains unaffected. Results from simulated Brazilian tests show that the tensile strength is influenced bythe presence of microcracks, with a reduction in tensile strength as microcrack intensity increases. Theimportance of microcrack heterogeneity in reproducing a bi-linear or S-shape failure envelope and itseffects on the mechanisms leading to spalling damage near an underground opening are also discussed.
基金the financial support from the NSFC(Grants 1372124)
文摘In the classical theory of elasticity,a body is initially modeled as a homogeneous and dense assemblage of constituent ＂material particles＂.The kernel concept of elastic deformation is the displacement of the particle that associates the current configuration with the reference one.In this paper,we exploit an alternative constituent ＂micro-finite element＂,and use the stretch of the element as the essential quality to recast the theory of elasticity.It should be realized that such a treatment means that the elastic body can be modeled as a finite covering of elements and consequently characterized by a manifold.The recasting of the elasticity theory becomes more feasible for dealing with defects and topological evolution.
文摘On the basis of the in situ data of DO2, pH, SiO2. PO4-P, NO3-N and NO2-N collected in the north of the East China Sea during 1987-1988, the following points are mainly expounded.1.The inorgonic nutrients are obviously affected by continent runoff in the north of the East China Sea. Their distributions are characteristic of its distribution of terrigenous materials.2.There are three transport paths of nutrients from the shelf to the Kuroshio area. The first is mixing-diffusing-advec-tion and upwelling process, the process of biology and biochemistry belongs to the second, and the sinking process is the last one.3.The swing of the Kuroshio axis affectes both the range of the migration of substances through mixing-diffusing-advec-tion process and the upwelling degree of the subsurface Kuroshio water to the shelf.4.Most part of the substances sink as macroparticles to the deep layer before reaching the Kuroshio area.
文摘AIM To reduce post treatments of kyphoplasty, as a common treatment for osteoporotic vertebrae.METHODS This study suggests a new method for treating vertebrae by setting the hexagonal porous structure instead of the rigid bone cement mass in the kyphoplasty(KP). The KP procedure was performed on the fresh ovine vertebra of the level L1. Micro finite element modeling was performed based on micro computed tomography of ovine trabecular cube. The hexagonal porous structure was set on one cube instead of the bone cement mass. For the implant designing, two geometrical parameters were considered: Spacing diameter and thickness.RESULTS The results of micro finite element analyses indicated the improvement in the mechanical behavior of the vertebra treated by the hexagonal porous structures, as compared to those treated by vertebroplasty(VP) and KP under static loading. The improvement in the mechanical behavior of the vertebra, was observed as 54% decrease in the amount of maximum Von Misses stress(improvement of stress distribution), in trabecular cube with embedded hexagonal structure, as compared to VP and KP. This is comparable to the results of the experimental study already performed; it was shown that the improvement of mechanical behavior of the vertebra was observed as: 83% increase in the range of displacements before getting to the ultimate strength(increasing the toughness) after setting hexagonal pearls inside vertebrae. Both the material and geometry of implant influenced the amount of Von Mises stress in the structure.CONCLUSION The new proposed method can be offered as a substitute for the KP. The implant geometry had a more obvious effect on the amount of Von Mises stress, as compared to the implant material.
基金supported by 973 Program of China under Grant No.2006CB302900part by the National Natural Science Foundation of China under Grant No.60825405 and No.60778018
文摘Several approaches to fabricate micro optical elements by use of half tone masks are studied and compared. It is shown that half tone masks employed in filtering image systems can obtain gray patterns with considerably high precision, but it is hard to operate from the viewpoint of operation. The method using contacting lithography technology or laser ablation can be easily operated with the cost of reducing fabrication precision and the trouble of choosing appropriate materials. For all of these methods, the coding of half tone masks with corrections for the nonlinear characteristics of coding, imaging and photoresist is recommended.
基金Funded by the National Natural Science Foundation of China(Nos.51108237 and 51178112)
文摘The micro-mechanical response of asphalt mixtures was studied using the discrete element method. The discrete element sample of stone mastic asphalt was generated first and the vehicle load was applied to the sample. A user-written program was coded with the FISH language in PFC3 D to extract the contact forces within the sample and the displacements of the particles. Then, the contact forces within the whole sample, in asphalt mastic, in coarse aggregates and between asphalt mastic and coarse aggregates were investigated. Finally, the movement of the particles in the sample was analyzed. The sample was divided into 15 areas and a figure was drawn to show how the balls move in each area according to the displacements of the balls in each area. The displacements of asphalt mastic balls and coarse aggregates were also analyzed. The experimental results explain how the asphalt mixture bears vehicle load and the potential reasons why the rutting forms from a micro-mechanical view.
文摘Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.
基金supported by the National Natural Science Foundation of China(Nos.10902046,11032006and11121202)the Fundamental Research Funds for the Central Universities(lzujbky-2012-2)+1 种基金the Fund of Ministry of Education of the Program of Changjiang Scholars and Innovative Research Team in University(No.IRT0628)the Science Foundation of the Ministry of Education of China for Ph.D.program
文摘Coupled thermo-mechanical analysis of two bonded functionally graded materials subjected to thermal loads is conducted in this study with the graded finite element method. The thermal-mechanical properties of the bi-material interfaces are classified based on discontinuity degrees of their material properties and their derivatives at the interfaces. Numerical results indicate that discontinuity exerts remarkable effect on the temperature profile and stress value at the interface of two bonded functionally-graded materials. Under the thermal flux loading conditions, the stronger the interface discontinuity is, the smaller the heat flux is.
文摘Vibrational behavior of thermally actuated cantilever micro-beams and their mechanical response at moderately high frequency under a non-harmonic periodic loading is studied in this paper. Two different configurations are considered: 1) a straight beam with two actuation layers on top and bottom which utilizes the bimorph effect to induce bending;2) a uniform beam with base excitation, where the beam is mounted on an actuator which moves it periodically at its base perpendicular to its axis. Generally, vibrating micro-cantilevers are required to oscillate at a specified frequency. In order to increase the efficiency of the system, and achieve deflections with low power consumption, geometrical features of the beams can be quantified so that the required vibrating frequency matches the natural frequencies of the beam. A parametric modal analysis is conducted on two configurations of micro-cantilever and the first natural frequency of the cantilevers as a function of geometrical parameters is extracted. To evaluate vibrational behavior and thermo-mechanical efficiency of micro-cantilevers as a function of their geometrical parameters and input power, a case study with a specified vibrating frequency is considered. Due to significant complexities in the loading conditions and thermo-mechanical behavior, this task can only be tackled via numerical methods. Selecting the geometrical parameters in order to induce resonance at the nominal frequency, non-linear time-history (transient) thermo-mechanical finite element analysis (using ANSYS) is run on each configuration to study its response to the periodic heating input. Approaches to improve the effectiveness of actuators in each configuration based on their implementation are investigated.
文摘Content of macro- and microelements in plant and soil was studied after biochar, compost, digestate, lignite, and lignohumate application. Pot experiments were carried out in Phytotron CLF Plant Master （Wertingen, Germany）. As tested plant lettuce （Lactucasativa） was used. Elemental composition was determined by AAS and XRF spectroscopy. Macronutrients content （Ca, Mg, K, and P） was determined by Mehlich III. Total content of carbon and nitrogen were determined by LECO TruSpec CN analyser. Results showed that different exogenous organic amendments statistically significantly influenced macro and micronutrients content in soil and plant. Satisfactory C/N ratio for soil microorganisms was measured only after compost and digestate application. As concerns hazardous elements, no legislation limits were overstepped after application of the tested organic amendments. Bioavailability and their uptake by plants followed the order： Cd 〉 Mn 〉 Zn 〉 Fe.
