The finite element artificial transmitting boundary method is employed here to treat the near field scattering of a cylindrical wave from an irregular cylinder. A comparison is made between this method and the analy...The finite element artificial transmitting boundary method is employed here to treat the near field scattering of a cylindrical wave from an irregular cylinder. A comparison is made between this method and the analytical one. And then examples are given to demonstrate the solution of several problems of the irregular object scattering. The method can not only produce clear physical pictures, but can efficiently handle many complicated scattering problems.展开更多
Combined with a digital bored photography system and in-situ statistics concerning the joints and fissures of both ore-body and surrounding rock,a 2D discrete model was constructed using UDEC.The stress field and disp...Combined with a digital bored photography system and in-situ statistics concerning the joints and fissures of both ore-body and surrounding rock,a 2D discrete model was constructed using UDEC.The stress field and displacement field changes of different sublevel stoping systems were also studied.Changes in the overlying rock strata settlement pattern has been analyzed and validated by in-situ monitoring data.The results show that:in the caving process,there exists an obvious delay and jump for the overlying rock strata displacement over time,and a stable arch can be formed in the process of caving,which leads to hidden goafs.Disturbed by the mining activity,a stress increase occurred in both the hanging wall and the foot wall,demonstrating a hump-shaped distribution pattern.From the comparison between simulation results and in-situ monitoring results,land subsidence shows a slow-development,suddenfailure,slow-development cycle pattern,which leads eventually to a stable state.This pattern validates the existence of balanced arch and hidden goafs.展开更多
In order to consider the effects of elastohydrodynamic lubrication(EHL) on contact fatigue reliability of spur gear, an accurate and efficient method that combines with response surface method(RSM) and first order sec...In order to consider the effects of elastohydrodynamic lubrication(EHL) on contact fatigue reliability of spur gear, an accurate and efficient method that combines with response surface method(RSM) and first order second moment method(FOSM) was developed for estimating the contact fatigue reliability of spur gear under EHL. The mechanical model of contact stress analysis of spur gear under EHL was established, in which the oil film pressure was mapped into hertz contact zone. Considering the randomness of EHL, material properties and fatigue strength correction factors, the proposed method was used to analyze the contact fatigue reliability of spur gear under EHL. Compared with the results of 1.5×105 by traditional Monte-Carlo, the difference between the two failure probability results calculated by the above mentioned methods is 2.2×10-4, the relative error of the failure probability results is 26.8%, and time-consuming only accounts for 0.14% of the traditional Monte-Carlo method(MCM). Sensitivity analysis results are in very good agreement with practical cognition. Analysis results show that the proposed method is precise and efficient, and could correctly reflect the influence of EHL on contact fatigue reliability of spur gear.展开更多
OBJECTIVE:To evaluate the effectiveness of a combined Traditional Chinese Medicine(TCM) therapy versus conventional treatment on adolescent idiopathic scoliosis.METHODS:One hundred twenty outpatients with mild and mod...OBJECTIVE:To evaluate the effectiveness of a combined Traditional Chinese Medicine(TCM) therapy versus conventional treatment on adolescent idiopathic scoliosis.METHODS:One hundred twenty outpatients with mild and moderate adolescent idiopathic scoliosis were randomly divided into a TCM group(TCMG)and a brace group(CG).TCMG patients underwent Daoyin,Tuina,and acupotomology therapies.CG patients were treated with a Milwaukee brace.Each patient's Cobb angle was measured after 12 and 24 months of treatment,and pulmonary function was determined after 12 months of treatment.Average electromyogram(AEMG) ratio of the surface electromyogram was measured after 6 and 12 months of treatment and followed-up after 18 and 24 months.RESULTS:The Cobb angle significantly decreased in both groups after 12 months of treatment compared with before treatment(P< 0.05).The percentages of original Cobb angle in TCMG and CG were51.4%and 47.8%(P > 0.05) after 12 months and62.5%and 34.7%(P < 0.05) after 24 months,respectively.Pulmonary function significantly improved after 12 months in TCMG(P < 0.05) but significantly decreased in CG(P < 0.05).The AEMG ratio was significantly lower(P < 0.01) and tended to remain at1 after stopping treatment in TCMG,but increased in CG(P<0.05).CONCLUSION:TCM combined therapy can prevent the progression of scoliosis.The AEMG ratio is a promising index that could replace radiography in the evaluation of treatment effect and progression in scoliosis.展开更多
The effective propagation constants of plane longitudinal and shear waves in nanoporous material with random distributed parallel cylindrical nanoholes are studied. The surface elastic theory is used to consider the s...The effective propagation constants of plane longitudinal and shear waves in nanoporous material with random distributed parallel cylindrical nanoholes are studied. The surface elastic theory is used to consider the surface stress effects and to derive the nontraditional boundary condition on the surface of nanoholes. The plane wave expansion method is used to obtain the scattering waves from the single nanohole. The multiple scattering effects are taken into consideration by summing the scat- tered waves from all scatterers and performing the configuration averaging of random distributed scatterers. The effective propagation constants of coherent waves along with the associated dynamic effective elastic modulus are numerically evaluat- ed. The influences of surface stress are discussed based on the numerical results.展开更多
文摘The finite element artificial transmitting boundary method is employed here to treat the near field scattering of a cylindrical wave from an irregular cylinder. A comparison is made between this method and the analytical one. And then examples are given to demonstrate the solution of several problems of the irregular object scattering. The method can not only produce clear physical pictures, but can efficiently handle many complicated scattering problems.
基金financially supported by the National Natural Science Foundation of China(No.51374033)the Doctoral Program of Higher Education Research Fund(No.20120006110022)the Chenchao Iron Mine and the technical support of Itasca
文摘Combined with a digital bored photography system and in-situ statistics concerning the joints and fissures of both ore-body and surrounding rock,a 2D discrete model was constructed using UDEC.The stress field and displacement field changes of different sublevel stoping systems were also studied.Changes in the overlying rock strata settlement pattern has been analyzed and validated by in-situ monitoring data.The results show that:in the caving process,there exists an obvious delay and jump for the overlying rock strata displacement over time,and a stable arch can be formed in the process of caving,which leads to hidden goafs.Disturbed by the mining activity,a stress increase occurred in both the hanging wall and the foot wall,demonstrating a hump-shaped distribution pattern.From the comparison between simulation results and in-situ monitoring results,land subsidence shows a slow-development,suddenfailure,slow-development cycle pattern,which leads eventually to a stable state.This pattern validates the existence of balanced arch and hidden goafs.
基金Project(CX2014B060)supported by Hunan Provincial Innovation for Postgraduate,ChinaProject(8130208)supported by General Armament Pre-research Foundation,China
文摘In order to consider the effects of elastohydrodynamic lubrication(EHL) on contact fatigue reliability of spur gear, an accurate and efficient method that combines with response surface method(RSM) and first order second moment method(FOSM) was developed for estimating the contact fatigue reliability of spur gear under EHL. The mechanical model of contact stress analysis of spur gear under EHL was established, in which the oil film pressure was mapped into hertz contact zone. Considering the randomness of EHL, material properties and fatigue strength correction factors, the proposed method was used to analyze the contact fatigue reliability of spur gear under EHL. Compared with the results of 1.5×105 by traditional Monte-Carlo, the difference between the two failure probability results calculated by the above mentioned methods is 2.2×10-4, the relative error of the failure probability results is 26.8%, and time-consuming only accounts for 0.14% of the traditional Monte-Carlo method(MCM). Sensitivity analysis results are in very good agreement with practical cognition. Analysis results show that the proposed method is precise and efficient, and could correctly reflect the influence of EHL on contact fatigue reliability of spur gear.
基金Supported by Outstanding Youth Fund of the Administration of Traditional Chinese Medicine of Zhejiang Province,China(No.2012ZQ011)
文摘OBJECTIVE:To evaluate the effectiveness of a combined Traditional Chinese Medicine(TCM) therapy versus conventional treatment on adolescent idiopathic scoliosis.METHODS:One hundred twenty outpatients with mild and moderate adolescent idiopathic scoliosis were randomly divided into a TCM group(TCMG)and a brace group(CG).TCMG patients underwent Daoyin,Tuina,and acupotomology therapies.CG patients were treated with a Milwaukee brace.Each patient's Cobb angle was measured after 12 and 24 months of treatment,and pulmonary function was determined after 12 months of treatment.Average electromyogram(AEMG) ratio of the surface electromyogram was measured after 6 and 12 months of treatment and followed-up after 18 and 24 months.RESULTS:The Cobb angle significantly decreased in both groups after 12 months of treatment compared with before treatment(P< 0.05).The percentages of original Cobb angle in TCMG and CG were51.4%and 47.8%(P > 0.05) after 12 months and62.5%and 34.7%(P < 0.05) after 24 months,respectively.Pulmonary function significantly improved after 12 months in TCMG(P < 0.05) but significantly decreased in CG(P < 0.05).The AEMG ratio was significantly lower(P < 0.01) and tended to remain at1 after stopping treatment in TCMG,but increased in CG(P<0.05).CONCLUSION:TCM combined therapy can prevent the progression of scoliosis.The AEMG ratio is a promising index that could replace radiography in the evaluation of treatment effect and progression in scoliosis.
基金the National Natural Science Foundation of China (Grant Nos. 10972029 and 40906044)the Youth Scientific Research Foundation PLA University of Science and Technology (Grant No. 20110510)
文摘The effective propagation constants of plane longitudinal and shear waves in nanoporous material with random distributed parallel cylindrical nanoholes are studied. The surface elastic theory is used to consider the surface stress effects and to derive the nontraditional boundary condition on the surface of nanoholes. The plane wave expansion method is used to obtain the scattering waves from the single nanohole. The multiple scattering effects are taken into consideration by summing the scat- tered waves from all scatterers and performing the configuration averaging of random distributed scatterers. The effective propagation constants of coherent waves along with the associated dynamic effective elastic modulus are numerically evaluat- ed. The influences of surface stress are discussed based on the numerical results.
