Aim:To investigate the effect of home-based cardiac rehabilitation on functional capacity,health behavior,and risk factors in patients with acute coronary syndrome in China.Methods:Eighty patients with acute coronary ...Aim:To investigate the effect of home-based cardiac rehabilitation on functional capacity,health behavior,and risk factors in patients with acute coronary syndrome in China.Methods:Eighty patients with acute coronary syndrome were enrolled in this prospective randomized controlled study.Patients in the cardiac rehabilitation group(n=52)received home-based cardiac rehabilitation with a heart manual and a home exercise video for 3 months and patients in the control group(n=28)received only routine secondary prevention.The 6-min walk distance,laboratory test results,healthy behavior(questionnaire),quality of life(12-item Short Form Health Survey),anxiety(7-item Generalized Anxiety Disorder Questionnaire),and depression(9-item Patient Health Questionnaire)were evaluated at the beginning and after treatment for 3 months.Results:Compared with baseline data,52 patients who participated in cardiac rehabilitation had longer 6-min walk distance(515.26±113.74 m vs 0.445.30±97.92 m,P<0.0002),higher proportions of“always exercise”(78.26% vs.28%,P<0.05),“always limit food with sugar”(65.22% vs 12%,P<0.05),“always eat fruits 200–400 g every day”(82.61% vs.4%,P<0.05).and“always eat vegetables 300–500 g every day”(21.74%vs.12%,P<0.06)after treatment for 3 months.The low-density lipoprotein cholesterol control rate(52.17% vs.28%,P<0.05)and the systolic blood pressure control rate(100%vs.68%,P<0.05)were also signifi cantly increased after treatment for 3 months in the cardiac rehabilitation group.No signifi cant increase was found in the control group after treatment for 3 months.No cardiac-event related to home exercise was reported in both groups.Conclusion:Home-based cardiac rehabilitation is a feasible and available cardiac rehabilitation mode in China.展开更多
The influence of different coating formulas and times on the water and oil resistance of paperboard was studied. The water and oil resistance of paperboard coated with a modified butadiene-styrene copolymer latex and ...The influence of different coating formulas and times on the water and oil resistance of paperboard was studied. The water and oil resistance of paperboard coated with a modified butadiene-styrene copolymer latex and fluorinated anion grease-proof agent was better than that coated with modified butadiene-styrene copolymer latex,where the modified butadiene-styrene copolymer latex was used as the pre-coating substrate and the F1516 fluorinated grease-proof agent was used as the top coating material. By coating modified butadiene-styrene copolymer latex with 30% solid content and F1516 fluorinated grease-proof agent with 24% solid content,the oil resistance of paperboard could reach anti-oil grade 12 and the water resistance could increased by98. 64%( compared with the base paperboard without any coating treatment).展开更多
A three-dimensional viscous code has been developed to solve Reynolds-averaged Navier-Stokes equations. The governing equations in finite volume form are solved by two-step Runge-Kutta scheme with implicit residual sm...A three-dimensional viscous code has been developed to solve Reynolds-averaged Navier-Stokes equations. The governing equations in finite volume form are solved by two-step Runge-Kutta scheme with implicit residual smoothing. The eddy viscous is obtained using the Baldwin-Lomax model. A prediction of the 3-D turbulent flow and the performance in the “all-over controlled vortex distribution” centrifugal impeller with a vaneless diffuser has been made for the compressor at design and off-design condition. The predicted effi-ciency is a little higher than the experiment data. These results suggest that the present calculation code is able to determine the flow development in the impeller and also the turbulence model in the centrifugal im-peller should be improved.展开更多
The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large num...The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density.展开更多
The emergence of curved shield tunnels poses a significant construction challenge.If the quality of the segment assembly is not guaranteed,many segment cracks and damage will result from the stress concentration.Sensi...The emergence of curved shield tunnels poses a significant construction challenge.If the quality of the segment assembly is not guaranteed,many segment cracks and damage will result from the stress concentration.Sensing the contact stresses between segmental joints is necessary to improve the quality of segments assembled for shield tunnel construction.Polyvinylidene difluoride(PVDF)piezoelectric material was chosen for the sensor because it can convert contact stresses into electrical signals,allowing the state of the segmental joints to be effectively sensed.It matches the working environment between the segmental joints of the shield tunnel,where flexible structures such as rubber gaskets and force transfer pads are present.This study proposes a piezoelectric sensing method for segmental joints in shield tunnels and conducts laboratory tests,numerical analyses,and field tests to validate the feasibility of the method.The results indicate that the PVDF film sensor can effectively sense the entire compression process of the gasket with different amounts of compression.The piezoelectric cable sensor can effectively sense the joint offset direction of the gasket.For differently shaped sections,the variation in the force sensed by the piezoelectric cable sensors was different,as verified by numerical simulation.Through the field test,it was found that the average contact stress between the segmental joints was in the range of 1.2–1.8 MPa during construction of the curved shield tunnels.The location of the segmental joints and the type of segment affect the contact stress value.The field monitoring results show that piezoelectric sensing technology can be successfully applied during assembly of the segments for effective sensing of the contact stress.展开更多
To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compres...To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compressor cascades.Considering the limited samples,the leadingedge angle and leading-edge radius distribution forms were evaluated by Shapiro-Wilk test and quantile–quantile plot.Their statistical characteristics provided can be introduced to later related researches.The parameterization design method B-spline and Bezier are adopted to create geometry models with manufacturing error based on leading-edge angle and leading-edge radius.The influence of real manufacturing error is quantified and analyzed by self-developed non-intrusive polynomial chaos and Sobol’indices.The mechanism of leading-edge manufacturing error on aerodynamic performance is discussed.The results show that the total pressure loss coefficient is sensitive to the leading-edge manufacturing error compared with the static pressure ratio,especially at high incidence.Specifically,manufacturing error of the leading edge will influence the local flow acceleration and subsequently cause fluctuation of the downstream flow.The aerodynamic performance is sensitive to the manufacturing error of leading-edge radius at the design and negative incidences,while it is sensitive to the manufacturing error of leading-edge angle under the operation conditions with high incidences.展开更多
An optical-based technique using Pressure-Sensitive Paint（PSP） is a promising method to measure the distribution of surface pressure on an aerodynamic model. The static and dynamic characteristics of a fast-response...An optical-based technique using Pressure-Sensitive Paint（PSP） is a promising method to measure the distribution of surface pressure on an aerodynamic model. The static and dynamic characteristics of a fast-response PSP that is developed in the Chinese Academy of Sciences（CAS）are analyzed and tested to serve as the basis for experiments on unsteady surface measurement using a fast-response PSP. Two calibration systems used for this study are set up to investigate the temperature dependency, response time, and resolution. A data processing method, used for dynamic data, is analyzed and selected carefully to determine the optimum signal. Results show that the fastresponse PSP can be used normally at temperatures from 25 ℃ to 80 ℃. The effect of temperature on the accuracy of the measurement must be considered when temperatures are beyond the temperature range of 30–40 ℃. The dynamic calibration device with a solenoid valve can achieve a pressure jump within a millisecond order. The resolution is determined by the signal-to-noise ratio of the photo-multiplier tube. Results of the measurement show that the response time of the PSP decreases with a large pressure variation, and the response time is below 0.016 s when the pressure variation is under 40 kPa.展开更多
The present paper aims at introducing Shear-Sensitive Liquid Crystal Coating(SSLCC)technology into compressor cascade measurement for the first time and serves as a basis for better understanding of the influence from...The present paper aims at introducing Shear-Sensitive Liquid Crystal Coating(SSLCC)technology into compressor cascade measurement for the first time and serves as a basis for better understanding of the influence from the boundary layers. Optical path layout, which is the most significant difficulty in internal flow field measurement, will be solved in this paper by selfdesigned image acquisition device. Massive experiments with different Mach number and incidence are conducted at a continuous subsonic cascade wind tunnel to capture the boundary layer phenomenon. Image processing methods, such as Three-Dimensional(3-D) reconstruction and Hue conversion, are used to improve the accuracy for transition position detection. The analysis of the color-images indicates that complex flow phenomena including transition, flow separation,and reattachment are captured successfully, and the effect of Mach number and incidence on the boundary layer flow is also discussed. The results show that: the Mach number has a significant effect on transition position; the incidence has little effect on transition position, but it has a great impact on the transition distance and leading-edge separation; influenced by the end-walls, the reattachment occurs in advance under positive angle of attack conditions.展开更多
The paper presented topology optimization of 2 D and 3 D Nanofluid-Cooled Heat Sink(NCHS). The flow and heat transfer problem in the NCHS was treated as a single-phase nanofluid based convective heat transfer model. T...The paper presented topology optimization of 2 D and 3 D Nanofluid-Cooled Heat Sink(NCHS). The flow and heat transfer problem in the NCHS was treated as a single-phase nanofluid based convective heat transfer model. The temperature-dependent fluid properties were taken into account in the model due to the strong temperature-dependent features of nanofluids. An average temperature minimum problem was studied subject to the fluid area and energy dissipation constraints by using the density method. In the method, the design variable is updated according to the gradient information obtained by an adjoint based sensitivity analysis process. The effects of the energy dissipation constraint, temperature-dependent fluid properties and nanofluid characteristics on optimal configurations of NCHS were numerically investigated with following conclusions.Firstly, branched flow channels in the optimal configuration increased with the rise of the allowed energy dissipation. Secondly, temperature-dependent fluid properties were significant for obtaining the appropriate optimal results with best cooling performance. Thirdly, heat transfer performances of optimal configurations were enhanced by reducing the nanoparticle diameter or increasing the nanoparticle volume fraction. Fourthly, the optimal configuration for nanofluid had better cooling performance than that for its base fluid.展开更多
文摘Aim:To investigate the effect of home-based cardiac rehabilitation on functional capacity,health behavior,and risk factors in patients with acute coronary syndrome in China.Methods:Eighty patients with acute coronary syndrome were enrolled in this prospective randomized controlled study.Patients in the cardiac rehabilitation group(n=52)received home-based cardiac rehabilitation with a heart manual and a home exercise video for 3 months and patients in the control group(n=28)received only routine secondary prevention.The 6-min walk distance,laboratory test results,healthy behavior(questionnaire),quality of life(12-item Short Form Health Survey),anxiety(7-item Generalized Anxiety Disorder Questionnaire),and depression(9-item Patient Health Questionnaire)were evaluated at the beginning and after treatment for 3 months.Results:Compared with baseline data,52 patients who participated in cardiac rehabilitation had longer 6-min walk distance(515.26±113.74 m vs 0.445.30±97.92 m,P<0.0002),higher proportions of“always exercise”(78.26% vs.28%,P<0.05),“always limit food with sugar”(65.22% vs 12%,P<0.05),“always eat fruits 200–400 g every day”(82.61% vs.4%,P<0.05).and“always eat vegetables 300–500 g every day”(21.74%vs.12%,P<0.06)after treatment for 3 months.The low-density lipoprotein cholesterol control rate(52.17% vs.28%,P<0.05)and the systolic blood pressure control rate(100%vs.68%,P<0.05)were also signifi cantly increased after treatment for 3 months in the cardiac rehabilitation group.No signifi cant increase was found in the control group after treatment for 3 months.No cardiac-event related to home exercise was reported in both groups.Conclusion:Home-based cardiac rehabilitation is a feasible and available cardiac rehabilitation mode in China.
文摘The influence of different coating formulas and times on the water and oil resistance of paperboard was studied. The water and oil resistance of paperboard coated with a modified butadiene-styrene copolymer latex and fluorinated anion grease-proof agent was better than that coated with modified butadiene-styrene copolymer latex,where the modified butadiene-styrene copolymer latex was used as the pre-coating substrate and the F1516 fluorinated grease-proof agent was used as the top coating material. By coating modified butadiene-styrene copolymer latex with 30% solid content and F1516 fluorinated grease-proof agent with 24% solid content,the oil resistance of paperboard could reach anti-oil grade 12 and the water resistance could increased by98. 64%( compared with the base paperboard without any coating treatment).
文摘A three-dimensional viscous code has been developed to solve Reynolds-averaged Navier-Stokes equations. The governing equations in finite volume form are solved by two-step Runge-Kutta scheme with implicit residual smoothing. The eddy viscous is obtained using the Baldwin-Lomax model. A prediction of the 3-D turbulent flow and the performance in the “all-over controlled vortex distribution” centrifugal impeller with a vaneless diffuser has been made for the compressor at design and off-design condition. The predicted effi-ciency is a little higher than the experiment data. These results suggest that the present calculation code is able to determine the flow development in the impeller and also the turbulence model in the centrifugal im-peller should be improved.
基金the foundation of National Natural Science Foundation of China(No.52376163)National Key Laboratory of Science and Technology on Aerodynamic Design and Research(No.614220121050327).
文摘The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density.
基金supported by the National Natural Science Foundation of China(Grant Nos.51978162 and 52278398).
文摘The emergence of curved shield tunnels poses a significant construction challenge.If the quality of the segment assembly is not guaranteed,many segment cracks and damage will result from the stress concentration.Sensing the contact stresses between segmental joints is necessary to improve the quality of segments assembled for shield tunnel construction.Polyvinylidene difluoride(PVDF)piezoelectric material was chosen for the sensor because it can convert contact stresses into electrical signals,allowing the state of the segmental joints to be effectively sensed.It matches the working environment between the segmental joints of the shield tunnel,where flexible structures such as rubber gaskets and force transfer pads are present.This study proposes a piezoelectric sensing method for segmental joints in shield tunnels and conducts laboratory tests,numerical analyses,and field tests to validate the feasibility of the method.The results indicate that the PVDF film sensor can effectively sense the entire compression process of the gasket with different amounts of compression.The piezoelectric cable sensor can effectively sense the joint offset direction of the gasket.For differently shaped sections,the variation in the force sensed by the piezoelectric cable sensors was different,as verified by numerical simulation.Through the field test,it was found that the average contact stress between the segmental joints was in the range of 1.2–1.8 MPa during construction of the curved shield tunnels.The location of the segmental joints and the type of segment affect the contact stress value.The field monitoring results show that piezoelectric sensing technology can be successfully applied during assembly of the segments for effective sensing of the contact stress.
基金the National Natural Science Foundation of China(No.51790512)the 111 Project(No.B17037)the National Key Laboratory Foundation,Industry-Academia-Research Collaboration Project of Aero Engine Corporation of China(No.HFZL2018CXY011-1)and MIIT。
文摘To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compressor cascades.Considering the limited samples,the leadingedge angle and leading-edge radius distribution forms were evaluated by Shapiro-Wilk test and quantile–quantile plot.Their statistical characteristics provided can be introduced to later related researches.The parameterization design method B-spline and Bezier are adopted to create geometry models with manufacturing error based on leading-edge angle and leading-edge radius.The influence of real manufacturing error is quantified and analyzed by self-developed non-intrusive polynomial chaos and Sobol’indices.The mechanism of leading-edge manufacturing error on aerodynamic performance is discussed.The results show that the total pressure loss coefficient is sensitive to the leading-edge manufacturing error compared with the static pressure ratio,especially at high incidence.Specifically,manufacturing error of the leading edge will influence the local flow acceleration and subsequently cause fluctuation of the downstream flow.The aerodynamic performance is sensitive to the manufacturing error of leading-edge radius at the design and negative incidences,while it is sensitive to the manufacturing error of leading-edge angle under the operation conditions with high incidences.
基金cosupported by the ‘‘111 Project” of China (No.B17037)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University of China (No.CX201713)the National Natural Science Foundation of China (No.51476132)
文摘An optical-based technique using Pressure-Sensitive Paint（PSP） is a promising method to measure the distribution of surface pressure on an aerodynamic model. The static and dynamic characteristics of a fast-response PSP that is developed in the Chinese Academy of Sciences（CAS）are analyzed and tested to serve as the basis for experiments on unsteady surface measurement using a fast-response PSP. Two calibration systems used for this study are set up to investigate the temperature dependency, response time, and resolution. A data processing method, used for dynamic data, is analyzed and selected carefully to determine the optimum signal. Results show that the fastresponse PSP can be used normally at temperatures from 25 ℃ to 80 ℃. The effect of temperature on the accuracy of the measurement must be considered when temperatures are beyond the temperature range of 30–40 ℃. The dynamic calibration device with a solenoid valve can achieve a pressure jump within a millisecond order. The resolution is determined by the signal-to-noise ratio of the photo-multiplier tube. Results of the measurement show that the response time of the PSP decreases with a large pressure variation, and the response time is below 0.016 s when the pressure variation is under 40 kPa.
基金co-supported by the National Natural Science Foundation of China(No.51476132)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX201713)the 111 Project(No.B17037)
文摘The present paper aims at introducing Shear-Sensitive Liquid Crystal Coating(SSLCC)technology into compressor cascade measurement for the first time and serves as a basis for better understanding of the influence from the boundary layers. Optical path layout, which is the most significant difficulty in internal flow field measurement, will be solved in this paper by selfdesigned image acquisition device. Massive experiments with different Mach number and incidence are conducted at a continuous subsonic cascade wind tunnel to capture the boundary layer phenomenon. Image processing methods, such as Three-Dimensional(3-D) reconstruction and Hue conversion, are used to improve the accuracy for transition position detection. The analysis of the color-images indicates that complex flow phenomena including transition, flow separation,and reattachment are captured successfully, and the effect of Mach number and incidence on the boundary layer flow is also discussed. The results show that: the Mach number has a significant effect on transition position; the incidence has little effect on transition position, but it has a great impact on the transition distance and leading-edge separation; influenced by the end-walls, the reattachment occurs in advance under positive angle of attack conditions.
基金supported by the National Natural Science Foundation of China (No. 51905435)Fundamental Research Funds for the Central Universities (No.G2018KY0306)supported by the National Natural Science Foundation of China (No. 51790512)。
文摘The paper presented topology optimization of 2 D and 3 D Nanofluid-Cooled Heat Sink(NCHS). The flow and heat transfer problem in the NCHS was treated as a single-phase nanofluid based convective heat transfer model. The temperature-dependent fluid properties were taken into account in the model due to the strong temperature-dependent features of nanofluids. An average temperature minimum problem was studied subject to the fluid area and energy dissipation constraints by using the density method. In the method, the design variable is updated according to the gradient information obtained by an adjoint based sensitivity analysis process. The effects of the energy dissipation constraint, temperature-dependent fluid properties and nanofluid characteristics on optimal configurations of NCHS were numerically investigated with following conclusions.Firstly, branched flow channels in the optimal configuration increased with the rise of the allowed energy dissipation. Secondly, temperature-dependent fluid properties were significant for obtaining the appropriate optimal results with best cooling performance. Thirdly, heat transfer performances of optimal configurations were enhanced by reducing the nanoparticle diameter or increasing the nanoparticle volume fraction. Fourthly, the optimal configuration for nanofluid had better cooling performance than that for its base fluid.
