Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investiga...Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed channel.The investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence model.The numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement.展开更多
A meshless simulation system is presented for elastic deformation driven by skeleton in this paper. In this system, we propose a new method for calculating node rotation while applying a similar technique with stiffne...A meshless simulation system is presented for elastic deformation driven by skeleton in this paper. In this system, we propose a new method for calculating node rotation while applying a similar technique with stiffness warping to tackle the nonlinear large deformation. In our method, all node rotations are evaluated from sampling points in attached skeleton by con- structing and solving the diffusion partial differential equation. The experiments indicated that the method can enhance the sta- bility of the dynamics and avoid fussy sub-step calculation in static deformation edition. Moreover, rational deformation results for the area around the skeleton joints can be simulated without user interaction by adopting the simplified technique.展开更多
Fracture system plays a very important role in the enrichment and accumulation of oil and gas in the reservoirs. Based on scattering wave information, Fracture Orientation Function （FOF） was built, which can be used...Fracture system plays a very important role in the enrichment and accumulation of oil and gas in the reservoirs. Based on scattering wave information, Fracture Orientation Function （FOF） was built, which can be used to predict the fracture orientations. However, this method has only been verified by physical experiments without studies on the application scope. In this study, based on the linear sliding theory, F0F of the scattering wave was applied to the numerical simulation and the application scope was further studied according to fracture flexibility tensor. According to the fractures filled with gas and liquid, numerical simulation was conducted on the models with various fracture flexibilities. Numerical simulation results were used to inverse fracture orientation with the aid of the FOF of the scattering wave. The results show that it is workable to predict the vertical fracture orientation with the F0F of the scattering wave. Application of this method is more effective when the fractures are filled with gas than liquid. Moreover, the application scope can be predicted by the fracture flexibility.展开更多
A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbit...A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbits were osteotomized and fixed with rigid plates and stress-relaxation plates, respectively. Stress shielding rate and ultimate bending strength of the healing bone were measured at 2 to 48 weeks postoperatively. Ratios of stress stimulation and fracture strength of the healing bone to those of intact bone were taken as the system input and output. The assumed first order system model can approximate the experimental data on fracture strength from the input of stress stimulation over time, both for the rigid plate group and the stress-relaxation plate group, with different system parameters of time constant and gain. The fitting curve indicates that the effect of mechanical stimulus occurs mainly in late stages of healing. First order system can model the stress adaptation process of fracture healing. This approach presents a simple bio-mathematical model of the relationship between stress stimulation and fracture strength, and has the potential to optimize planning of functional exercises and conduct parametric studies.展开更多
Apatite coating with nanobelt structure was fabricated on single crystal silicon by a two-step method of electrodeposition at 1.0-2.0 mA/cm2 with DC power and vapor-thermal treatment(VTT) at 150-180℃ for 6 h over alk...Apatite coating with nanobelt structure was fabricated on single crystal silicon by a two-step method of electrodeposition at 1.0-2.0 mA/cm2 with DC power and vapor-thermal treatment(VTT) at 150-180℃ for 6 h over alkali medium.Scanning electron microscopy(SEM),X-ray diffractometry(XRD),and electron diffraction spectrometry(EDS) were employed to investigate the compositions and morphologies of specimens before or after vapor-thermal treatment.The results demonstrate that nanobelt crystals of coating,0.5-2 μm in width,100 nm in thickness,and 6-10 μm in length,are Ca-deficient apatite(CDA) with a mole ratio of Ca to P approximately of 1.60,which shows similarity of the nanobelt coating to inorganic phase in composition and to collagen in dimension appearing in human hard tissue.Induced nucleation and growth of bone-like apatite were observed on the nanobelt after soaking in a simulated body fluid(SBF) for 6 h and for 3 d,respectively,identifying that nanobelt has good ability for induction of bone-like apatite in SBF.展开更多
The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this ...The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this paper, based on Lu and Torquato＇s most nearest surface distribution function, a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete. Then, quantitative formulas are put forward to measure the influencing factors on the ｜TZ vol- ume fraction. In order to validate the given model, the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation. The results show that the two are in good agreement. The order of the factors influencing the ITZ volume fraction is the ITZ thickness, the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn. The 1TZ volume fraction obtained from the equal volume fraction （EVF） gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.展开更多
Objective:To observe the clinical efficacy of acupoint injection with salmon calcitonin for back pain in elderly patients with primary osteoporosis.Methods:A total of 76 patients were selected and randomly divided int...Objective:To observe the clinical efficacy of acupoint injection with salmon calcitonin for back pain in elderly patients with primary osteoporosis.Methods:A total of 76 patients were selected and randomly divided into two groups by the random number table method,with 39 cases in the treatment group and 37 cases in the control group,respectively.Patients in both groups received routine anti-osteoporosis treatment.Patients in the treatment group received additional acupoint injection with salmon calcitonin at bilateral Pishu(BL 20)and Shenshu(BL 23),while patients in the control group received additional intramuscular injection with salmon calcitonin.The treatments for both groups were given once a day and lasted for 4 weeks.Visual analog scale(VAS)and Chinese Oswestry disability index(CODI)scores were observed before treatment,after 2 weeks and 4 weeks of treatment,and the use of analgesics during the treatment were recorded.Results:After treatment,the clinical efficacy in the treatment group was more significant than that in the control group(P<0.05).After 2 weeks and 4 weeks of treatment,the VAS scores in both groups showed significant intra-group and between-group differences(all P<0.05),and the CODI scores in both groups showed significant intra-group differences(all P<0.05).After 2 weeks of treatment,the CODI score showed no significant between-group difference(P>0.05).After 4 weeks of treatment,the improvement of CODI score in the treatment group was more significant than that in the control group(P<0.05).During the treatment,2 cases in the treatment group took analgesics versus 8 cases in the control group,and the result showed a significant between-group difference(P<0.05).Conclusion:For back pain in elderly patients with primary osteoporosis,based on the routine treatment of oral medication,the clinical efficacy of acupoint injection with salmon calcitonin at bilateral Pishu(BL 20)and Shenshu(BL 23)is more significant than that of intramuscular injection.Acupoint injection treatment can improve patients'conditions and reduce the use of analgesics.展开更多
基金Supported by the Guangdong Science and Technology Project (2008A01070003)
文摘Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed channel.The investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence model.The numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement.
基金Project supported by the National Basic Research Program (973) of China (No. 2002CB312102) and the National Natural Science Foun-dation of China (Nos. 60021201, 60333010 and 60505001)
文摘A meshless simulation system is presented for elastic deformation driven by skeleton in this paper. In this system, we propose a new method for calculating node rotation while applying a similar technique with stiffness warping to tackle the nonlinear large deformation. In our method, all node rotations are evaluated from sampling points in attached skeleton by con- structing and solving the diffusion partial differential equation. The experiments indicated that the method can enhance the sta- bility of the dynamics and avoid fussy sub-step calculation in static deformation edition. Moreover, rational deformation results for the area around the skeleton joints can be simulated without user interaction by adopting the simplified technique.
基金supported by the National Basic Research Program of China ( No. 2014CB239104 and No. 2012CB214800)National Science and Technology Major Project of the Ministry of Science and Technology of China ( No. 2011ZX05066-002)
文摘Fracture system plays a very important role in the enrichment and accumulation of oil and gas in the reservoirs. Based on scattering wave information, Fracture Orientation Function （FOF） was built, which can be used to predict the fracture orientations. However, this method has only been verified by physical experiments without studies on the application scope. In this study, based on the linear sliding theory, F0F of the scattering wave was applied to the numerical simulation and the application scope was further studied according to fracture flexibility tensor. According to the fractures filled with gas and liquid, numerical simulation was conducted on the models with various fracture flexibilities. Numerical simulation results were used to inverse fracture orientation with the aid of the FOF of the scattering wave. The results show that it is workable to predict the vertical fracture orientation with the F0F of the scattering wave. Application of this method is more effective when the fractures are filled with gas than liquid. Moreover, the application scope can be predicted by the fracture flexibility.
基金Project (No. 39470698) supported by the National Natural Science Foundation of China
文摘A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbits were osteotomized and fixed with rigid plates and stress-relaxation plates, respectively. Stress shielding rate and ultimate bending strength of the healing bone were measured at 2 to 48 weeks postoperatively. Ratios of stress stimulation and fracture strength of the healing bone to those of intact bone were taken as the system input and output. The assumed first order system model can approximate the experimental data on fracture strength from the input of stress stimulation over time, both for the rigid plate group and the stress-relaxation plate group, with different system parameters of time constant and gain. The fitting curve indicates that the effect of mechanical stimulus occurs mainly in late stages of healing. First order system can model the stress adaptation process of fracture healing. This approach presents a simple bio-mathematical model of the relationship between stress stimulation and fracture strength, and has the potential to optimize planning of functional exercises and conduct parametric studies.
基金Project(50702020) supported by the National Natural Science Foundation of China
文摘Apatite coating with nanobelt structure was fabricated on single crystal silicon by a two-step method of electrodeposition at 1.0-2.0 mA/cm2 with DC power and vapor-thermal treatment(VTT) at 150-180℃ for 6 h over alkali medium.Scanning electron microscopy(SEM),X-ray diffractometry(XRD),and electron diffraction spectrometry(EDS) were employed to investigate the compositions and morphologies of specimens before or after vapor-thermal treatment.The results demonstrate that nanobelt crystals of coating,0.5-2 μm in width,100 nm in thickness,and 6-10 μm in length,are Ca-deficient apatite(CDA) with a mole ratio of Ca to P approximately of 1.60,which shows similarity of the nanobelt coating to inorganic phase in composition and to collagen in dimension appearing in human hard tissue.Induced nucleation and growth of bone-like apatite were observed on the nanobelt after soaking in a simulated body fluid(SBF) for 6 h and for 3 d,respectively,identifying that nanobelt has good ability for induction of bone-like apatite in SBF.
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2009CB623200)the National High-Tech Research and Development Program of China ("863" Project)(Grant No. 2008AA030794)
文摘The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this paper, based on Lu and Torquato＇s most nearest surface distribution function, a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete. Then, quantitative formulas are put forward to measure the influencing factors on the ｜TZ vol- ume fraction. In order to validate the given model, the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation. The results show that the two are in good agreement. The order of the factors influencing the ITZ volume fraction is the ITZ thickness, the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn. The 1TZ volume fraction obtained from the equal volume fraction （EVF） gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.
文摘Objective:To observe the clinical efficacy of acupoint injection with salmon calcitonin for back pain in elderly patients with primary osteoporosis.Methods:A total of 76 patients were selected and randomly divided into two groups by the random number table method,with 39 cases in the treatment group and 37 cases in the control group,respectively.Patients in both groups received routine anti-osteoporosis treatment.Patients in the treatment group received additional acupoint injection with salmon calcitonin at bilateral Pishu(BL 20)and Shenshu(BL 23),while patients in the control group received additional intramuscular injection with salmon calcitonin.The treatments for both groups were given once a day and lasted for 4 weeks.Visual analog scale(VAS)and Chinese Oswestry disability index(CODI)scores were observed before treatment,after 2 weeks and 4 weeks of treatment,and the use of analgesics during the treatment were recorded.Results:After treatment,the clinical efficacy in the treatment group was more significant than that in the control group(P<0.05).After 2 weeks and 4 weeks of treatment,the VAS scores in both groups showed significant intra-group and between-group differences(all P<0.05),and the CODI scores in both groups showed significant intra-group differences(all P<0.05).After 2 weeks of treatment,the CODI score showed no significant between-group difference(P>0.05).After 4 weeks of treatment,the improvement of CODI score in the treatment group was more significant than that in the control group(P<0.05).During the treatment,2 cases in the treatment group took analgesics versus 8 cases in the control group,and the result showed a significant between-group difference(P<0.05).Conclusion:For back pain in elderly patients with primary osteoporosis,based on the routine treatment of oral medication,the clinical efficacy of acupoint injection with salmon calcitonin at bilateral Pishu(BL 20)and Shenshu(BL 23)is more significant than that of intramuscular injection.Acupoint injection treatment can improve patients'conditions and reduce the use of analgesics.
