To simulate the actual flowfield at the exit of the supersonic/hypersonic inlet, a wind tunnel is designed to study the flow in the scramjet isolator under the asymmetric incoming flow. And compression fields in the i...To simulate the actual flowfield at the exit of the supersonic/hypersonic inlet, a wind tunnel is designed to study the flow in the scramjet isolator under the asymmetric incoming flow. And compression fields in the isolator are investigated using wall static and pitot pressure measurements. Three incoming Mach numbers are considered as 1.5, 1.8 and 2. Results show that the increase of the asymmetry of the flow at the isolator entrance leads to the increase of the shock train length in the isolator for a given pressure ratio. Based on the analysis of the flow asymmetry effect at the isolator entrance on the shock train length, a modified correlation is proposed to calculate the length of the shock train. Predicted results of the proposed correlation are in good agreement with the experimental data.展开更多
Split Hopkinson Pressure Bar(SHPB) test was simulated to investigate the distribution of the first principal stress and damage zone of specimen subjected to dynamic compressive load. Numerical models of plate-type spe...Split Hopkinson Pressure Bar(SHPB) test was simulated to investigate the distribution of the first principal stress and damage zone of specimen subjected to dynamic compressive load. Numerical models of plate-type specimen containing cracks with inclined angles of 0°,45° and 90° were also established to investigate the crack propagation and damage evolution under dynamic loading. The results show that the simulation results are in accordance with the failure patterns of specimens in experimental test. The interactions between stress wave and crack with different inclined angles are different; damage usually appears around the crack tips firstly; and then more damage zones develop away from the foregoing damage zone after a period of energy accumulation; eventually,the damage zones run through the specimen in the direction of applied loading and split the specimen into pieces.展开更多
Nanoindentation tests were conducted to investigate the near-surface mechanical properties of the individual components(fiber and matrix) for three-dimensional reinforced carbon/carbon composites(3D C/C).Optical micro...Nanoindentation tests were conducted to investigate the near-surface mechanical properties of the individual components(fiber and matrix) for three-dimensional reinforced carbon/carbon composites(3D C/C).Optical microscope and polarizing light microscope were used to characterize the microstructure of 3D C/C.The microscopy results show that large number of pores and cracks exist at both bundle/matrix interface and pitch carbon matrix.These defects have important effect on the mechanical behavior of 3D C/C.The in situ properties for components of 3D C/C were acquired by nanoindentation technique.Relative to the matrix sample,the fiber samples have more larger values for modulus,stiffness and hardness.However,there is no significant difference of modulus and stiffness among fiber samples with different directions.展开更多
The hot compression test of 6063 Al alloy was performed on a Gleeble-1500 thermo-simulation machine, and the forming of 6063 rod cxtrudate in low-temperature high-speed extrusion was simulated with extrusion ratio of ...The hot compression test of 6063 Al alloy was performed on a Gleeble-1500 thermo-simulation machine, and the forming of 6063 rod cxtrudate in low-temperature high-speed extrusion was simulated with extrusion ratio of 25 on the platform of DEFORM 2D successfully. From the compression experimental results, the flow stress model of this Al alloy is obtained which could be the constitutive equation in the simulation of low-temperature high-speed extrusion process. From the numerical simulation results, there is a higher strain concentration at the entrance of the die and the exit temperature reaches up to 522 ℃ in low-temperature high-speed extrusion, which approaches to the quenching temperature of the 6063 Al alloy. The results show that the low-temperature high-speed extrusion method as a promsing one can reduce energy consumption effectively.展开更多
Overheating of the engine, the transmission and the hydraulic device is a problem when the construction machinery works on plateau. To solve this problem, we proposed an electro-controlled hydraulic driving fan coolin...Overheating of the engine, the transmission and the hydraulic device is a problem when the construction machinery works on plateau. To solve this problem, we proposed an electro-controlled hydraulic driving fan cooling system (ECHDFCS). The system was applied to a 50-wheel loader. We carried out the coolant temperature simulation using fluid modeling software FLOWMASTER, followed by laboratory experiments and road tests. The results show that ECHDFCS can adjust the cooling capability of the system automatically based on machine heat dissipation requirements. The coolant temperature is consequently remained within an appropriate range. The simulation results are consistent with the experiment results when the experiment is performed on the plain, but are different from the road tests in some investigated parameters on the plateau.展开更多
The mechanical properties of jointed rock masses, such as strength, deformation and the failure mechanism, can be understood only by studying the sensitivity of jointed rock mass strength (both the peak and residual s...The mechanical properties of jointed rock masses, such as strength, deformation and the failure mechanism, can be understood only by studying the sensitivity of jointed rock mass strength (both the peak and residual strengths) to the factors that affect it. An orthogonal design of uniaxial compression tests was simulated on eighteen groups of jointed rock specimens having different geometric and mechanical properties using RFPA2D (Rock Failure Process Analysis) code. The results show that the peak strength is controlled by the geometric parameters of the joints, but that the residual strength is controlled by the mechanical prop- erties of the joint interfaces. The failure mode of jointed rock specimens is mainly shear failure. Joint quantity, or density, is the most important index that affects jointed rock mass strength and engineering quality.展开更多
Venous thromboembolism （VTE） is the commonest cause of preventable death in hospitalized patients. Elderly patients have higher risk of VTE because of the high prevalence of predisposing co-morbidities and acute ill...Venous thromboembolism （VTE） is the commonest cause of preventable death in hospitalized patients. Elderly patients have higher risk of VTE because of the high prevalence of predisposing co-morbidities and acute illnesses. Clinical diagnosis of VTE in the elderly patient is particularly difficult and, as such, adequate VTE prophylaxis is of pivotal importance in reducing the mortality and morbidities of VTE. Omission of VTE prophylaxis is, however, very common despite continuous education. A simple way to overcome this problem is to implement universal VTE prophylaxis for all hospitalized elderly patients instead of selective prophylaxis for some patients only according to individual＇ s risk of VTE. Although pharmacological VTE prophylaxis is effective for most patients, a high prevalence of renal impairment and drug interactions in the hospitalized elderly patients suggests that a multimodality approach may be more appropriate. Mechanical VTE prophylaxis, including calf and thigh compression devices and/or an inferior vena cava filter, are often underutilized in hospitalized elderly patients who are at high-risk of bleeding and VTE. Because pneumatic compression devices and thigh length stockings are virtually risk free, mechanical VTE prophylaxis may allow early or immediate implementation of VTE prophylaxis for all hospitalized elderly patients, regardless of their bleeding and VTE risk. Although the cost-effectiveness of this Multimodality Universal STat （＇MUST＇） VTE prophylaxis approach for hospitalized elderly patients remains uncertain, this strategy appears to offer some advantages over the traditional ＇selective and single-modal＇ VTE prophylaxis approach, which often becomes ＇hit or miss＇ or not implemented promptly in many hospitalized elderly patients. A large clustered randomized controlled trial is, however, needed to assess whether early, multimodality, universal VTE prophylaxis can improve important clinical outcomes of hospitalized elderly patients.展开更多
A test system of the permeability of broken coal samples mainly consists of a CMT5305 electronic universal test machine, crushed rock compaction containing cylinder and a self-designed seepage circuit, which is compos...A test system of the permeability of broken coal samples mainly consists of a CMT5305 electronic universal test machine, crushed rock compaction containing cylinder and a self-designed seepage circuit, which is composed of a gear pump, a reversing valve, a relief valve and other components. By using the steady penetration method, the permeability and non-Darcy flow β factor of broken coal samples under five different porosity levels were measured, the grain diameters of the coal samples were selected as 2.5-5 mm, 5-10 mm, 10-15 mm, 15-20 mm, 20-25 mm and 2.5-25 ram, respectively. After measuring the permeability under each porosity, the overfall pressure of the relief valve continuously increased until the coal sample was broken down. In this way, the flow type of liquid inside the broken coal samples changed from seepage to pipe flow. The correlation between breakdown pressure gradient （BPG） and porosity was analyzed, and the BPG was compared with the pressure gradient when seepage instability occurred. The results show that, ①the non-Darcy flow β factor was negative before broken coal samples with six kinds of diameters were broken down; ②the BPG of coal samples with a grain size of 2.5-25 mm was lower than that of the others; ③ the BPG of coal samples with a single diameter under the same porosity increased as the grain size increased; ④ the BPG could be fitted by an exponential function with porosity, and the exponent decreased as the grain size increased for coal samples with a single diameter; ⑤ the BPG was slightly less than the seepage instability pressure gradient. The change in liquid flow type from seepage to pipe flow could be regarded as the performance of the seepage instability.展开更多
For Gu-Ag alloy, an important parameter called workability in the forming process of materials can be evaluated by processing maps yielded from the stress-strain data generated by hot compression tests at temperatures...For Gu-Ag alloy, an important parameter called workability in the forming process of materials can be evaluated by processing maps yielded from the stress-strain data generated by hot compression tests at temperatures of 700-850 °C and strain rates of 0.01-10 s-1. And at the true strain of 0.15, 0.35 and 0.55, respectively, the responses of strain-rate sensitivity, power dissipation efficiency and instability parameter to temperature and strain rate were studied. Instability maps and power dissipation maps were superimposed to form processing maps, which reveal the determinate regions where individual metallurgical processes occur and the limiting conditions of flow instability regions. Furthermore, the optimal processing parameters for bulk metal working are identified clearly by the processing maps.展开更多
This work describes a study of tabletting of selected Malaysian herbs such as Eurycoma longifolia Jack, Ficus deltoidea and Morinda citrifolia. These herbs are famous for their therapeutic properties and are used as h...This work describes a study of tabletting of selected Malaysian herbs such as Eurycoma longifolia Jack, Ficus deltoidea and Morinda citrifolia. These herbs are famous for their therapeutic properties and are used as herbal medicine or as medicinal food. A cylindrical uniaxial die of 13 mm was used to compress the herb powders into tablets. Pressures ranging from 7.5 MPa to 75 MPa were applied using a universal testing machine. Two feed weights, 0.5 g and 1.0 g, were used to produce the tablets. A binder, the microcrystalline cellulose known as Avicel, was used to investigate its effect on tabletting. Properties associated with both the binder and the compounds were studied, and binary mixtures with compositions ranging from 10% to 60% were examined. The strength of the herb tablets was then tested using an indirect tensile strength test. Upon compression, the Morinda citrifolia powder showed the highest density compared to that of Avicel. However, due to its high elasticity, the tensile strength of the Morinda citrifolia tablet was the lowest. The experimental data were also verified using an established model for compression property development. The results indicated that this simple approach can be used to understand the tabletting characteristics of these herbs.展开更多
This paper presents a detailed experimental investigation concerning the influence of blade loading (incidence) on the three-dimensional flow in an annular compressor cascade.The data are acquired at four incidence an...This paper presents a detailed experimental investigation concerning the influence of blade loading (incidence) on the three-dimensional flow in an annular compressor cascade.The data are acquired at four incidence angles under low Mach number and low Reynolds number conditions.Experimental techniquss include the oil-film visualization on the profile and the endwall surfaces,the laser-sheet visualization of the flow field inside the blade passage,and the measurement by radial-circumferential traveress using a seven-hole probe.The behavior and nature of the three-dimensional flow with severe separations inside the blade passage and at the exit are obtained.The distributions of the total pressure loss,static pressure,velocity and outflow angle are also given. These results are valuable for establishing the physical model of the three-dimensional complex flow in axial compressors and for examining the computational procedures.展开更多
In order to investigate the effects of probe support on the stall characteristics of micro compressors, an experiment was carried out on a large-scale low-speed research compressor according to the principle of geomet...In order to investigate the effects of probe support on the stall characteristics of micro compressors, an experiment was carried out on a large-scale low-speed research compressor according to the principle of geometric similarity. A cylindrical probe support intruding to 50% blade span was mounted at 50% chord upstream from the rotor blade leading edge. The static pressure rise characteristic of the compressor is measured, with and without the probe support respectively. The dynamic compressor behavior from pre-stall to full stall was also measured. The results indicate that the stability margin of the compressor is lowered after installing the probe support. The stall inception is aroused by modal wave disturbances. The disturbances developed into two stall cells smoothly before installing the probe support, while the disturbances first developed into a single stall cell then splitting into two stall cells after installing the probe support. The presence of probe support lowers the initial intensity of the rotating stall of the compressor, while it doesn't alter the intensity of the rotation stall after the compressor enters into full stall.展开更多
Objective:To explore the efficacy and mechanism of warm needling moxibustion plus percutaneous kyphoplasty(PKP)for osteoporotic vertebral compression fracture(OVCF)due to kidney deficiency and blood stasis.Methods:A t...Objective:To explore the efficacy and mechanism of warm needling moxibustion plus percutaneous kyphoplasty(PKP)for osteoporotic vertebral compression fracture(OVCF)due to kidney deficiency and blood stasis.Methods:A total of 70 OVCF patients were randomized into a control group and an observation group,with 35 cases in each group.The control group was given PKP treatment,and the observation group was treated with warm needling moxibustion on the basis of the treatment in the control group.The visual analog scale(VAS)and Oswestry disability index(ODI)were scored and the Cobb angle of fractured vertebrae was measured before and after treatment.The re-fracture rate of the adjacent vertebrae was recorded at 1-year follow-up.The serum levels of transforming growth factor(TGF)-β1 and omentin-1 were measured before and after treatment.Results:After treatment,the VAS and ODI scores in both groups decreased(all P<0.05),and all the scores in the observation group were lower than those in the control group(both P<0.05).After treatment,the Cobb angle of fractured vertebrae in both groups decreased(both P<0.05),and the Cobb angle in the observation group was smaller than that in the control group(P<0.05).At 1-year follow-up,the re-fracture rate of the adjacent vertebrae in the observation group was lower than that in the control group(P<0.05).After treatment,the serum levels of TGF-β1 and omentin-1 in both groups increased significantly(all P<0.05),and the serum levels of TGF-β1 and omentin-1 in the observation group were higher than those in the control group(both P<0.05).Conclusion:The treatment of warm needling moxibustion plus PKP can relieve pain,improve dysfunction,promote healing of the injured vertebrae,and reduce the re-fracture rate of the adjacent vertebrae in patients with OVCF due to kidney deficiency and blood stasis,which may be related to the increase of serum TGF-β1 and omentin-1 levels.展开更多
文摘To simulate the actual flowfield at the exit of the supersonic/hypersonic inlet, a wind tunnel is designed to study the flow in the scramjet isolator under the asymmetric incoming flow. And compression fields in the isolator are investigated using wall static and pitot pressure measurements. Three incoming Mach numbers are considered as 1.5, 1.8 and 2. Results show that the increase of the asymmetry of the flow at the isolator entrance leads to the increase of the shock train length in the isolator for a given pressure ratio. Based on the analysis of the flow asymmetry effect at the isolator entrance on the shock train length, a modified correlation is proposed to calculate the length of the shock train. Predicted results of the proposed correlation are in good agreement with the experimental data.
基金Projects(50534030, 50674107, 50490274) supported by the National Natural Science Foundation of ChinaProject(06JJ3028) supported by the Provincial Natural Science Foundation of Hunan, China
文摘Split Hopkinson Pressure Bar(SHPB) test was simulated to investigate the distribution of the first principal stress and damage zone of specimen subjected to dynamic compressive load. Numerical models of plate-type specimen containing cracks with inclined angles of 0°,45° and 90° were also established to investigate the crack propagation and damage evolution under dynamic loading. The results show that the simulation results are in accordance with the failure patterns of specimens in experimental test. The interactions between stress wave and crack with different inclined angles are different; damage usually appears around the crack tips firstly; and then more damage zones develop away from the foregoing damage zone after a period of energy accumulation; eventually,the damage zones run through the specimen in the direction of applied loading and split the specimen into pieces.
基金Project(61391) supported by the National Security Basic Research Program of ChinaProject (91016029) supported by the National Natural Science Foundation of China
文摘Nanoindentation tests were conducted to investigate the near-surface mechanical properties of the individual components(fiber and matrix) for three-dimensional reinforced carbon/carbon composites(3D C/C).Optical microscope and polarizing light microscope were used to characterize the microstructure of 3D C/C.The microscopy results show that large number of pores and cracks exist at both bundle/matrix interface and pitch carbon matrix.These defects have important effect on the mechanical behavior of 3D C/C.The in situ properties for components of 3D C/C were acquired by nanoindentation technique.Relative to the matrix sample,the fiber samples have more larger values for modulus,stiffness and hardness.However,there is no significant difference of modulus and stiffness among fiber samples with different directions.
基金Project(2008A09030004) supported by the Major Science and Technology Project of Guangdong Province,ChinaProject(30815009) supported by the Foundation of State Key Laboratory of Advanced Design and Manufacture for Vehicle Body
文摘The hot compression test of 6063 Al alloy was performed on a Gleeble-1500 thermo-simulation machine, and the forming of 6063 rod cxtrudate in low-temperature high-speed extrusion was simulated with extrusion ratio of 25 on the platform of DEFORM 2D successfully. From the compression experimental results, the flow stress model of this Al alloy is obtained which could be the constitutive equation in the simulation of low-temperature high-speed extrusion process. From the numerical simulation results, there is a higher strain concentration at the entrance of the die and the exit temperature reaches up to 522 ℃ in low-temperature high-speed extrusion, which approaches to the quenching temperature of the 6063 Al alloy. The results show that the low-temperature high-speed extrusion method as a promsing one can reduce energy consumption effectively.
基金Funded by the Innovation Foundation of Guangzhou, P. R. China (No. 2005V42C0021)
文摘Overheating of the engine, the transmission and the hydraulic device is a problem when the construction machinery works on plateau. To solve this problem, we proposed an electro-controlled hydraulic driving fan cooling system (ECHDFCS). The system was applied to a 50-wheel loader. We carried out the coolant temperature simulation using fluid modeling software FLOWMASTER, followed by laboratory experiments and road tests. The results show that ECHDFCS can adjust the cooling capability of the system automatically based on machine heat dissipation requirements. The coolant temperature is consequently remained within an appropriate range. The simulation results are consistent with the experiment results when the experiment is performed on the plain, but are different from the road tests in some investigated parameters on the plateau.
基金The financial supports from the National Natural Science Foundation of China (No.50674083)the Eleventh Five-Year Plan of National Scientific and Technological Support of China (No.2008BAB36 B07)the Jiangsu Civil Engineering Graduate Center for Innovation and Academic Communication Foundation
文摘The mechanical properties of jointed rock masses, such as strength, deformation and the failure mechanism, can be understood only by studying the sensitivity of jointed rock mass strength (both the peak and residual strengths) to the factors that affect it. An orthogonal design of uniaxial compression tests was simulated on eighteen groups of jointed rock specimens having different geometric and mechanical properties using RFPA2D (Rock Failure Process Analysis) code. The results show that the peak strength is controlled by the geometric parameters of the joints, but that the residual strength is controlled by the mechanical prop- erties of the joint interfaces. The failure mode of jointed rock specimens is mainly shear failure. Joint quantity, or density, is the most important index that affects jointed rock mass strength and engineering quality.
文摘Venous thromboembolism （VTE） is the commonest cause of preventable death in hospitalized patients. Elderly patients have higher risk of VTE because of the high prevalence of predisposing co-morbidities and acute illnesses. Clinical diagnosis of VTE in the elderly patient is particularly difficult and, as such, adequate VTE prophylaxis is of pivotal importance in reducing the mortality and morbidities of VTE. Omission of VTE prophylaxis is, however, very common despite continuous education. A simple way to overcome this problem is to implement universal VTE prophylaxis for all hospitalized elderly patients instead of selective prophylaxis for some patients only according to individual＇ s risk of VTE. Although pharmacological VTE prophylaxis is effective for most patients, a high prevalence of renal impairment and drug interactions in the hospitalized elderly patients suggests that a multimodality approach may be more appropriate. Mechanical VTE prophylaxis, including calf and thigh compression devices and/or an inferior vena cava filter, are often underutilized in hospitalized elderly patients who are at high-risk of bleeding and VTE. Because pneumatic compression devices and thigh length stockings are virtually risk free, mechanical VTE prophylaxis may allow early or immediate implementation of VTE prophylaxis for all hospitalized elderly patients, regardless of their bleeding and VTE risk. Although the cost-effectiveness of this Multimodality Universal STat （＇MUST＇） VTE prophylaxis approach for hospitalized elderly patients remains uncertain, this strategy appears to offer some advantages over the traditional ＇selective and single-modal＇ VTE prophylaxis approach, which often becomes ＇hit or miss＇ or not implemented promptly in many hospitalized elderly patients. A large clustered randomized controlled trial is, however, needed to assess whether early, multimodality, universal VTE prophylaxis can improve important clinical outcomes of hospitalized elderly patients.
基金Supported by the National Natural Science Foundation of China （50974107） the University Graduate Research and Innovation Project in Jiangsu Province （CXZZI2_0924）+1 种基金 the Applied Basic Research Project of Yancheng Institute of Technology （XKR2010010） the State Key Laboratory Open Foundation of Deep Geomechanics and Underground Engineering of China University of Mining and Technology （SKLGDUEK1014）
文摘A test system of the permeability of broken coal samples mainly consists of a CMT5305 electronic universal test machine, crushed rock compaction containing cylinder and a self-designed seepage circuit, which is composed of a gear pump, a reversing valve, a relief valve and other components. By using the steady penetration method, the permeability and non-Darcy flow β factor of broken coal samples under five different porosity levels were measured, the grain diameters of the coal samples were selected as 2.5-5 mm, 5-10 mm, 10-15 mm, 15-20 mm, 20-25 mm and 2.5-25 ram, respectively. After measuring the permeability under each porosity, the overfall pressure of the relief valve continuously increased until the coal sample was broken down. In this way, the flow type of liquid inside the broken coal samples changed from seepage to pipe flow. The correlation between breakdown pressure gradient （BPG） and porosity was analyzed, and the BPG was compared with the pressure gradient when seepage instability occurred. The results show that, ①the non-Darcy flow β factor was negative before broken coal samples with six kinds of diameters were broken down; ②the BPG of coal samples with a grain size of 2.5-25 mm was lower than that of the others; ③ the BPG of coal samples with a single diameter under the same porosity increased as the grain size increased; ④ the BPG could be fitted by an exponential function with porosity, and the exponent decreased as the grain size increased for coal samples with a single diameter; ⑤ the BPG was slightly less than the seepage instability pressure gradient. The change in liquid flow type from seepage to pipe flow could be regarded as the performance of the seepage instability.
基金Project(CSTC2009BA4065) supported by the Chongqing Natural Science Foundation,China
文摘For Gu-Ag alloy, an important parameter called workability in the forming process of materials can be evaluated by processing maps yielded from the stress-strain data generated by hot compression tests at temperatures of 700-850 °C and strain rates of 0.01-10 s-1. And at the true strain of 0.15, 0.35 and 0.55, respectively, the responses of strain-rate sensitivity, power dissipation efficiency and instability parameter to temperature and strain rate were studied. Instability maps and power dissipation maps were superimposed to form processing maps, which reveal the determinate regions where individual metallurgical processes occur and the limiting conditions of flow instability regions. Furthermore, the optimal processing parameters for bulk metal working are identified clearly by the processing maps.
文摘This work describes a study of tabletting of selected Malaysian herbs such as Eurycoma longifolia Jack, Ficus deltoidea and Morinda citrifolia. These herbs are famous for their therapeutic properties and are used as herbal medicine or as medicinal food. A cylindrical uniaxial die of 13 mm was used to compress the herb powders into tablets. Pressures ranging from 7.5 MPa to 75 MPa were applied using a universal testing machine. Two feed weights, 0.5 g and 1.0 g, were used to produce the tablets. A binder, the microcrystalline cellulose known as Avicel, was used to investigate its effect on tabletting. Properties associated with both the binder and the compounds were studied, and binary mixtures with compositions ranging from 10% to 60% were examined. The strength of the herb tablets was then tested using an indirect tensile strength test. Upon compression, the Morinda citrifolia powder showed the highest density compared to that of Avicel. However, due to its high elasticity, the tensile strength of the Morinda citrifolia tablet was the lowest. The experimental data were also verified using an established model for compression property development. The results indicated that this simple approach can be used to understand the tabletting characteristics of these herbs.
文摘This paper presents a detailed experimental investigation concerning the influence of blade loading (incidence) on the three-dimensional flow in an annular compressor cascade.The data are acquired at four incidence angles under low Mach number and low Reynolds number conditions.Experimental techniquss include the oil-film visualization on the profile and the endwall surfaces,the laser-sheet visualization of the flow field inside the blade passage,and the measurement by radial-circumferential traveress using a seven-hole probe.The behavior and nature of the three-dimensional flow with severe separations inside the blade passage and at the exit are obtained.The distributions of the total pressure loss,static pressure,velocity and outflow angle are also given. These results are valuable for establishing the physical model of the three-dimensional complex flow in axial compressors and for examining the computational procedures.
基金funded by the National Natural Science Foundation of China(Grant No.51161130525 and 51136003)the 111 Project,No.B07009
文摘In order to investigate the effects of probe support on the stall characteristics of micro compressors, an experiment was carried out on a large-scale low-speed research compressor according to the principle of geometric similarity. A cylindrical probe support intruding to 50% blade span was mounted at 50% chord upstream from the rotor blade leading edge. The static pressure rise characteristic of the compressor is measured, with and without the probe support respectively. The dynamic compressor behavior from pre-stall to full stall was also measured. The results indicate that the stability margin of the compressor is lowered after installing the probe support. The stall inception is aroused by modal wave disturbances. The disturbances developed into two stall cells smoothly before installing the probe support, while the disturbances first developed into a single stall cell then splitting into two stall cells after installing the probe support. The presence of probe support lowers the initial intensity of the rotating stall of the compressor, while it doesn't alter the intensity of the rotation stall after the compressor enters into full stall.
文摘Objective:To explore the efficacy and mechanism of warm needling moxibustion plus percutaneous kyphoplasty(PKP)for osteoporotic vertebral compression fracture(OVCF)due to kidney deficiency and blood stasis.Methods:A total of 70 OVCF patients were randomized into a control group and an observation group,with 35 cases in each group.The control group was given PKP treatment,and the observation group was treated with warm needling moxibustion on the basis of the treatment in the control group.The visual analog scale(VAS)and Oswestry disability index(ODI)were scored and the Cobb angle of fractured vertebrae was measured before and after treatment.The re-fracture rate of the adjacent vertebrae was recorded at 1-year follow-up.The serum levels of transforming growth factor(TGF)-β1 and omentin-1 were measured before and after treatment.Results:After treatment,the VAS and ODI scores in both groups decreased(all P<0.05),and all the scores in the observation group were lower than those in the control group(both P<0.05).After treatment,the Cobb angle of fractured vertebrae in both groups decreased(both P<0.05),and the Cobb angle in the observation group was smaller than that in the control group(P<0.05).At 1-year follow-up,the re-fracture rate of the adjacent vertebrae in the observation group was lower than that in the control group(P<0.05).After treatment,the serum levels of TGF-β1 and omentin-1 in both groups increased significantly(all P<0.05),and the serum levels of TGF-β1 and omentin-1 in the observation group were higher than those in the control group(both P<0.05).Conclusion:The treatment of warm needling moxibustion plus PKP can relieve pain,improve dysfunction,promote healing of the injured vertebrae,and reduce the re-fracture rate of the adjacent vertebrae in patients with OVCF due to kidney deficiency and blood stasis,which may be related to the increase of serum TGF-β1 and omentin-1 levels.
