The experimental installation and measurement system of ultrasonic wave property in rocks during complete stress-strain process were established and perfected. The interrelations between ultrasonic wave property of mu...The experimental installation and measurement system of ultrasonic wave property in rocks during complete stress-strain process were established and perfected. The interrelations between ultrasonic wave property of muds tone, sands tone and limestone specimens during complete stress-strain process and their mechanic property were investigated. A new type of device for the observation of surrounding rock stability-borehole ultrasonic device with completely dry coupling was developed to get better coupling and more accurate measurement data comparing with those of water coupling situation. Preliminary study on the application of ultrasonic measurement technique at belt conveyor roadway of north wing in Baodian Coal Mine (Shandong province) was conducted. Based on the interrelations between the complete stress-strain properties of specimens and their wave properties, the structural properties of surrounding rocks, the range of yield zones, and the change of stresses within surrounding rocks when a longwall face was across over the roadway were analyzed.Therefore,a new and feasible way was found for the research on the deformation law of surrounding rock of roadway and rational selection of support parameters.展开更多
The experimental tests for limestone specimens at 700 °C in uniaxial compression were carried out to inves- tigate the mechanical effects of loading rates on limestone by using a MTS810 rock mechanics servo- cont...The experimental tests for limestone specimens at 700 °C in uniaxial compression were carried out to inves- tigate the mechanical effects of loading rates on limestone by using a MTS810 rock mechanics servo- controlled testing system considering the loading rate as a variable. The mechanical properties of limestone such as the stress-strain curve, variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the strain rates ranging from 1.1 10à5 to 1.1 10à1 sà1. (1) Sharp decreases were shown for the peak strength and elastic modulus of limestone from 1.1 10à5 to 1.1 10à4 sà1 at 700 °C as well as a downward trend was shown from 1.1 10à4 to 1.1 10à1 sà1 with the rise of the strain rate. (2) The peak strain increased from 1.1 10à5 to 1.1 10à4 sà1, however, there was no obvious changes shown for the peak strain of limestone from 1.1 10à4 to 1.1 10à1 sà1. These results can provide valuable references for the rock blasting effect and design of mine.展开更多
The aim of this research was to find out whether the effect of chemical corrosion changes mechanical characteristics of surface layers of wooden construction elements. Degradation of the surface layers of wood was cau...The aim of this research was to find out whether the effect of chemical corrosion changes mechanical characteristics of surface layers of wooden construction elements. Degradation of the surface layers of wood was caused by chemical reactions of the basic substances of wood mass with compounds contained in antifire coatings. Fire retardants containing corrosive substances were often and repeatedly used in the Czech Republic on many wooden building constructions. This process of chemical corrosion is in practise called as ＂surface defibering of wood＂. This contribution presents standard and special experimental methods used for measuring the selected mechanical characteristics （compression strength, tension strength, bending strength, hardness and impact resistance） in the damaged surface layer of wooden construction elements. The material for experimental measuring was a construction element removed from a historical roof （ca 150 years old）. Mechanical characteristics of the surface layer of the defibered element were compared with the values measured in the deeper subsurface layer of non-damaged wood. The results of the experiments proved loss of cohesive strength and decrease of mechanical characteristics of wood only in a thin surface layer.展开更多
As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation...As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation is usually referenced in the evaluation of pulmonary status and assessment of respiratory therapy. In order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, in this paper, a new mathematical model of mechanical ventilation system was set up. Furthermore, a prototype mechanical ventilation system for an artificial simulating lung was designed and experimentally studied. Lastly, in order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, the air flow dynamics of the mechanical ventilation system was illustrated through simulation and experimental studies. The study can be helpful to the optimization of the mechanical ventilation system.展开更多
As the nano-motor becomes a mechanical reality, its prototype can be envisaged as nano-sized rotating machinery at a situation,albeit for different purposes, like that in the first half of the 20th century during whic...As the nano-motor becomes a mechanical reality, its prototype can be envisaged as nano-sized rotating machinery at a situation,albeit for different purposes, like that in the first half of the 20th century during which rotor dynamics has contributed toboosting machine power capacity. Accordingly, we take the benefit of hindsight to develop a classical framework of vibrationanalysis. Essentially, the equations of motion are formulated to cope with both the special carbon-nanotube properties and thefirst author’s previously developed spinning beam formalism, establishing a model satisfactorily verified by some availablemolecular dynamics (MD) data and classical spinning beam results extracted from the literature. The model is inexpensivebased on continuum mechanics as an alternative to the less-flexible MD method for simulating wave motion of the spinningsingle-walled carbon nanotube, yielding several interesting phenomena, including the fall-off and splitting of the wave charac-teristic curves and the unexpected gyroscopic phase property. Potential applications are proposed.展开更多
In this paper,we introduce our finding of the effects of C_(60) nanoparticles (NP) infiltration on mechanical properties of cell and its membrane.Atomic force microscopy (AFM) is used to perform indentation on both no...In this paper,we introduce our finding of the effects of C_(60) nanoparticles (NP) infiltration on mechanical properties of cell and its membrane.Atomic force microscopy (AFM) is used to perform indentation on both normal and C_(60) infiltrated red blood cells (RBC) to gain data of mechanical characteristics of the membrane.Our results show that the mechanical properties of human RBC membrane seem to be altered due to the presence of C_(60) NPs.The resistance and ultimate strength of the C_(60) infiltrated RBC membrane significantly decrease.We also explain the mechanism of how C_(60) NPs infiltration changes the mechanical properties of the cell membrane by predicting the structural change of the lipid bilayer caused by the C_(60) infiltration at molecular level and analyze the interactions among molecules in the lipid bilayer.The potential hazards and application of the change in mechanical characteristics of the RBCs membrane are also discussed.Nanotoxicity of C_(60) NPs may be significant for some biological cells.展开更多
A new type of homoclinic arid heteroclinic solutions, i.e. homoclinic and heteroclinic breather solutions, for Zakharov system are obtained using extended homoclinic test and two-soliton methods, respectively. Moreove...A new type of homoclinic arid heteroclinic solutions, i.e. homoclinic and heteroclinic breather solutions, for Zakharov system are obtained using extended homoclinic test and two-soliton methods, respectively. Moreover, the homoclinic and heteroclinic structure with local oscillation and mechanicaL feature different from homoclinic and heterocliunic solutions are investigated. Result shows complexity of dynamics for complex nonlineaR evolution system. Moreover, the similarities and differences between homoclinic （heteroclinic） breather and homoclinic （heteroclinic） tube are exhibited. These results show that the diversity of the structures of homoclinic and heteroclinic solutions.展开更多
Objective： To explore the mechanical behavior of lumbar spine loaded by stress and provide the mechanical basis for clinical analysis and judgement of lumbar spine fracture classification, mechanical distribution and...Objective： To explore the mechanical behavior of lumbar spine loaded by stress and provide the mechanical basis for clinical analysis and judgement of lumbar spine fracture classification, mechanical distribution and static stress. Methods： By means of computer simulation method, the constructed lumbar spine three-dimensional model was introduced into three-dimensional finite element analysis by software Ansys 7.0. The lumbar spine mechanical behavior in different parts of the stress loading were calculated. Impact load is 0-8000 N. The peak value was 8000 N. The loading time is 0-40 minutes. The values of the main stress, stress distribution and the lumbar spine unit displacement in the direction of main stress were analyzed. Results： The lumbar spine model was divided into a total of 121 239 nodes, 112 491 units. It could objectively reflect the true anatomy of lumbar spine and its biomechanical behavior and obtain the end-plate images under different stress. The stress distribution on the lumbar intervertebral disc （L3-L4） under the axial, lateral flexion and extension stress, and the displacement trace of the corresponding processus articularis were analyzed. Conclusion： It is helpful to analyze the stress distribution of lumbar spine and units displacement in static stress loading in the clinical research of lumbar spine injury and the distribution of internal stress.展开更多
基金This project is supported by returned specialists fund of China National Coal Corporation
文摘The experimental installation and measurement system of ultrasonic wave property in rocks during complete stress-strain process were established and perfected. The interrelations between ultrasonic wave property of muds tone, sands tone and limestone specimens during complete stress-strain process and their mechanic property were investigated. A new type of device for the observation of surrounding rock stability-borehole ultrasonic device with completely dry coupling was developed to get better coupling and more accurate measurement data comparing with those of water coupling situation. Preliminary study on the application of ultrasonic measurement technique at belt conveyor roadway of north wing in Baodian Coal Mine (Shandong province) was conducted. Based on the interrelations between the complete stress-strain properties of specimens and their wave properties, the structural properties of surrounding rocks, the range of yield zones, and the change of stresses within surrounding rocks when a longwall face was across over the roadway were analyzed.Therefore,a new and feasible way was found for the research on the deformation law of surrounding rock of roadway and rational selection of support parameters.
基金supported by the Fundamental Research Funds for the Central Universities (No. 2011QNB05)the National Basic Research Program of China (No. 2007CB209400)+2 种基金the National Natural Science Foundation of China (Nos. 51074166 and 51104128)the Research Project for Ministry of Housing and Urban-Rural Development of China (No. 2011-K3-5)the Innovation Project of Graduate Students in Jiangsu Province (No. CX09B_108Z)
文摘The experimental tests for limestone specimens at 700 °C in uniaxial compression were carried out to inves- tigate the mechanical effects of loading rates on limestone by using a MTS810 rock mechanics servo- controlled testing system considering the loading rate as a variable. The mechanical properties of limestone such as the stress-strain curve, variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the strain rates ranging from 1.1 10à5 to 1.1 10à1 sà1. (1) Sharp decreases were shown for the peak strength and elastic modulus of limestone from 1.1 10à5 to 1.1 10à4 sà1 at 700 °C as well as a downward trend was shown from 1.1 10à4 to 1.1 10à1 sà1 with the rise of the strain rate. (2) The peak strain increased from 1.1 10à5 to 1.1 10à4 sà1, however, there was no obvious changes shown for the peak strain of limestone from 1.1 10à4 to 1.1 10à1 sà1. These results can provide valuable references for the rock blasting effect and design of mine.
文摘The aim of this research was to find out whether the effect of chemical corrosion changes mechanical characteristics of surface layers of wooden construction elements. Degradation of the surface layers of wood was caused by chemical reactions of the basic substances of wood mass with compounds contained in antifire coatings. Fire retardants containing corrosive substances were often and repeatedly used in the Czech Republic on many wooden building constructions. This process of chemical corrosion is in practise called as ＂surface defibering of wood＂. This contribution presents standard and special experimental methods used for measuring the selected mechanical characteristics （compression strength, tension strength, bending strength, hardness and impact resistance） in the damaged surface layer of wooden construction elements. The material for experimental measuring was a construction element removed from a historical roof （ca 150 years old）. Mechanical characteristics of the surface layer of the defibered element were compared with the values measured in the deeper subsurface layer of non-damaged wood. The results of the experiments proved loss of cohesive strength and decrease of mechanical characteristics of wood only in a thin surface layer.
基金supported by the National Natural Science Foundation of China(Grant No.51575020)
文摘As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation is usually referenced in the evaluation of pulmonary status and assessment of respiratory therapy. In order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, in this paper, a new mathematical model of mechanical ventilation system was set up. Furthermore, a prototype mechanical ventilation system for an artificial simulating lung was designed and experimentally studied. Lastly, in order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, the air flow dynamics of the mechanical ventilation system was illustrated through simulation and experimental studies. The study can be helpful to the optimization of the mechanical ventilation system.
基金supported by the National Natural Science Foundation of China (Grant Nos.60936001, 11021262 and 11011120245)the National Basic Research Program of China (Grant No. 2007CB310500)
文摘As the nano-motor becomes a mechanical reality, its prototype can be envisaged as nano-sized rotating machinery at a situation,albeit for different purposes, like that in the first half of the 20th century during which rotor dynamics has contributed toboosting machine power capacity. Accordingly, we take the benefit of hindsight to develop a classical framework of vibrationanalysis. Essentially, the equations of motion are formulated to cope with both the special carbon-nanotube properties and thefirst author’s previously developed spinning beam formalism, establishing a model satisfactorily verified by some availablemolecular dynamics (MD) data and classical spinning beam results extracted from the literature. The model is inexpensivebased on continuum mechanics as an alternative to the less-flexible MD method for simulating wave motion of the spinningsingle-walled carbon nanotube, yielding several interesting phenomena, including the fall-off and splitting of the wave charac-teristic curves and the unexpected gyroscopic phase property. Potential applications are proposed.
基金supported by the National Natural Science Foundation of China (Grant Nos.10902128,11072271,10972239,51172291)Fundamental Research Funds for the Central Universities,New Century Excellent Talents in University and Research Funds for the Doctoral Program of Higher Education
文摘In this paper,we introduce our finding of the effects of C_(60) nanoparticles (NP) infiltration on mechanical properties of cell and its membrane.Atomic force microscopy (AFM) is used to perform indentation on both normal and C_(60) infiltrated red blood cells (RBC) to gain data of mechanical characteristics of the membrane.Our results show that the mechanical properties of human RBC membrane seem to be altered due to the presence of C_(60) NPs.The resistance and ultimate strength of the C_(60) infiltrated RBC membrane significantly decrease.We also explain the mechanism of how C_(60) NPs infiltration changes the mechanical properties of the cell membrane by predicting the structural change of the lipid bilayer caused by the C_(60) infiltration at molecular level and analyze the interactions among molecules in the lipid bilayer.The potential hazards and application of the change in mechanical characteristics of the RBCs membrane are also discussed.Nanotoxicity of C_(60) NPs may be significant for some biological cells.
基金Supported by the Natural Science Foundation of China under Grant No.11061028
文摘A new type of homoclinic arid heteroclinic solutions, i.e. homoclinic and heteroclinic breather solutions, for Zakharov system are obtained using extended homoclinic test and two-soliton methods, respectively. Moreover, the homoclinic and heteroclinic structure with local oscillation and mechanicaL feature different from homoclinic and heterocliunic solutions are investigated. Result shows complexity of dynamics for complex nonlineaR evolution system. Moreover, the similarities and differences between homoclinic （heteroclinic） breather and homoclinic （heteroclinic） tube are exhibited. These results show that the diversity of the structures of homoclinic and heteroclinic solutions.
文摘Objective： To explore the mechanical behavior of lumbar spine loaded by stress and provide the mechanical basis for clinical analysis and judgement of lumbar spine fracture classification, mechanical distribution and static stress. Methods： By means of computer simulation method, the constructed lumbar spine three-dimensional model was introduced into three-dimensional finite element analysis by software Ansys 7.0. The lumbar spine mechanical behavior in different parts of the stress loading were calculated. Impact load is 0-8000 N. The peak value was 8000 N. The loading time is 0-40 minutes. The values of the main stress, stress distribution and the lumbar spine unit displacement in the direction of main stress were analyzed. Results： The lumbar spine model was divided into a total of 121 239 nodes, 112 491 units. It could objectively reflect the true anatomy of lumbar spine and its biomechanical behavior and obtain the end-plate images under different stress. The stress distribution on the lumbar intervertebral disc （L3-L4） under the axial, lateral flexion and extension stress, and the displacement trace of the corresponding processus articularis were analyzed. Conclusion： It is helpful to analyze the stress distribution of lumbar spine and units displacement in static stress loading in the clinical research of lumbar spine injury and the distribution of internal stress.
