In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of fragments.Attention is paid to eluc...In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of fragments.Attention is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of fragments.The results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural parameters.In this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.展开更多
A multi-residual module stacked hourglass network(MRSH)was proposed to improve the accuracy and robustness of human body pose estimation.The network uses multiple hourglass sub-networks and three new residual modules....A multi-residual module stacked hourglass network(MRSH)was proposed to improve the accuracy and robustness of human body pose estimation.The network uses multiple hourglass sub-networks and three new residual modules.In the hourglass sub-network,the large receptive field residual module(LRFRM)and the multi-scale residual module(MSRM)are first used to learn the spatial relationship between features and body parts at various scales.Only the improved residual module(IRM)is used when the resolution is minimized.The final network uses four stacked hourglass sub-networks,with intermediate supervision at the end of each hourglass,repeating high-low(from high resolution to low resolution)and low-high(from low resolution to high resolution)learning.The network was tested on the public datasets of Leeds sports poses(LSP)and MPII human pose.The experimental results show that the proposed network has better performance in human pose estimation.展开更多
To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by ...To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by using a variable transmission ratio was developed.This method ensures that the rake angles on the indexing torus of each tooth are approximately 0°.Based on the gear meshing theory and the hourglass worm forming method,the discretization mathematical model of the rake face of a planar double enveloping worm gear hob was established by using cylindrical generating surface,and the feed parameters for machining the rake face for a variable transmission ratio were obtained.The spiral flute was simulated and the hob was machined on a four axis CNC milling machine.A contourgraph was used to measure the rake angle.The measurement results showed that the proposed method can reduce the absolute value of the rake angle on both sides of the cutting teeth,which can be used for machining the spiral flute rake face of an hourglass worm gear hob.展开更多
In gear transmission,temperature rise has a non-negligible impact on the accuracy,noise and transmission efficiency.However,there is no relevant research on the temperature rise of the anti-backlash single-roller enve...In gear transmission,temperature rise has a non-negligible impact on the accuracy,noise and transmission efficiency.However,there is no relevant research on the temperature rise of the anti-backlash single-roller enveloping hourglass worm(ASEHW)gear.To solve this problem,based on tribology principle and Hertz contact theory,the thermal power calculation method of the ASEHW gear was proposed for the first time and thermal analysis was carried out by Ansys software.The bulk temperature of the ASEHW gear under four different rotating speed(300 r/min,600 r/min,900 r/min,1200 r/min)is calculated.The main factors causing temperature rise of the ASEHW gear are analyzed theoretically.Meanwhile,an experimental study is performed to verify the simulation results and validate the theory methods.The theory presented in this paper provides a solution for the thermal power calculation of ASEHW gear.This research provides a theoretical basis for further optimization of ASEHW gear.展开更多
Based on solid modeling, the geometry and the FE model of the hourglass worm gearing are established. By the hybrid method of FEM and penalty function, the load sharing among tooth paris and the stress of contact teet...Based on solid modeling, the geometry and the FE model of the hourglass worm gearing are established. By the hybrid method of FEM and penalty function, the load sharing among tooth paris and the stress of contact teeth are calculated, the contact zones and the distribution of the contact pressure are investigated. The variation of the contact states with the load is investigated by comparision of its contact patterns under different loads.展开更多
The explosive growth of data volume in mobile networks makes fast online diagnose a pressing search problem. In this paper, an object-oriented detection framework with a two-step clustering, named as Hourglass Cluster...The explosive growth of data volume in mobile networks makes fast online diagnose a pressing search problem. In this paper, an object-oriented detection framework with a two-step clustering, named as Hourglass Clustering, is given. Where three object parameters are chosen as Synthetical Quality of Experience(SQo E) Key Quality Indicators(KQIs) to reflect accessibility, integrality, and maintainability of networks. Then, we choose represented Key Performance Indicators(r KPIs) as cause parameters with correlation analysis. For these two kinds of parameters, a hybrid algorithm combining the self-organizing map(SOM)展开更多
An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented, which is based on a 3-D elastic contact finite element method (FEM) model that accommodates the influen...An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented, which is based on a 3-D elastic contact finite element method (FEM) model that accommodates the influence of errors and load. As compared with existing tooth contact analysis model that assumes rigidity for the contacting surfaces, the proposed model provides a more realistic analysis on the contact patterns, the distribution of contact load and transmission errors. It is also capable of exploring the influence of different errors on meshing performances, the contact deformation, the shift of the contact zone and load share among the meshing tooth-pairs under different load.展开更多
Hourglass is remarkably aroused in ring rolling simulation with reduced integration element because of violent ring vibration and small contact area of ring with forming rollers. Hourglass energy can be reduced by imp...Hourglass is remarkably aroused in ring rolling simulation with reduced integration element because of violent ring vibration and small contact area of ring with forming rollers. Hourglass energy can be reduced by improving mesh density. Combined approach of artificial damping and artificial stiffness can control the hourglass. A ring with rectangular section is simulated with the weight factor of artificial stiffness resistance set to 0.2. The artificial damping hourglass control coefficient is set to 0.1, and the artificial stiffness hourglass control coefficient is set to 0.001. The ratio of hourglass energy to internal energy is reduced to 2.5 percent. Compared with axial spread width test, the effectiveness of hourglass control in ring rolling simulation is verified.展开更多
Recently,stacked hourglass network has shown outstanding performance in human pose estimation.However,repeated bottom-up and top-down stride convolution operations in deep convolutional neural networks lead to a signi...Recently,stacked hourglass network has shown outstanding performance in human pose estimation.However,repeated bottom-up and top-down stride convolution operations in deep convolutional neural networks lead to a significant decrease in the initial image resolution.In order to address this problem,we propose to incorporate affinage module and residual attention module into stacked hourglass network for human pose estimation.This paper introduces a novel network architecture to replace the stacked hourglass network of up-sampling operation for getting high-resolution features.We refer to the architecture as an affinage module which is critical to improve the performance of the stacked hourglass network.Additionally,we also propose a novel residual attention module to increase the supervision of up-sample process.The effectiveness of the introduced module is evaluated on standard benchmarks.Various experimental results demonstrated that our method can achieve more accurate and more robust human pose estimation results in images with complex background.展开更多
In this article,the design of the hourglass truss sandwich structure is improved by optimizing the number of layers to enhance the compressive strength of both the core and the face sheet and then its mechanical perfo...In this article,the design of the hourglass truss sandwich structure is improved by optimizing the number of layers to enhance the compressive strength of both the core and the face sheet and then its mechanical performance. The hourglass truss structures characterized by three different numbers of layers are manufactured using an interlocking and vacuum brazing method. The effect of the layer number of the hourglass core panels on their out-of-plane compression and in-plane compression performance is investigated,and the results from calculations and experiments are in reasonable agreement. The results show that as the layer number of the hourglass core increases,the out-of-plane compressive strengths show little change,but their energy absorption properties are effectively increased. The in-plane compressive failure mechanism maps are constructed,and the specimens are designed to examine the local elastic and inelastic buckling failure modes of the face sheets. The results suggest that as the number of layers of the hourglass core increases,its maximum in-plane compressive load increases. The maximum in-plane compressive loads of the two-layer hourglass truss panels are 57%–70% higher than those of the single-layer panels. It can also be concluded that the out-of-plane and in-plane compression mechanical properties of the multilayer hourglass truss outperform those of the pyramidal truss. Furthermore,the number of layers of the hourglass core is optimized in consideration of both mechanical properties and fabrication cost.展开更多
基金supported by the Defense Industrial Technology Development Program(Grant No.JCKY2018604B004)the National Natural Science Foundation of China(Grant No.11972007)。
文摘In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of fragments.Attention is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of fragments.The results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural parameters.In this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.
基金Supported by the National Natural Science Foundation of China(61401001,61501003,61672032)。
文摘A multi-residual module stacked hourglass network(MRSH)was proposed to improve the accuracy and robustness of human body pose estimation.The network uses multiple hourglass sub-networks and three new residual modules.In the hourglass sub-network,the large receptive field residual module(LRFRM)and the multi-scale residual module(MSRM)are first used to learn the spatial relationship between features and body parts at various scales.Only the improved residual module(IRM)is used when the resolution is minimized.The final network uses four stacked hourglass sub-networks,with intermediate supervision at the end of each hourglass,repeating high-low(from high resolution to low resolution)and low-high(from low resolution to high resolution)learning.The network was tested on the public datasets of Leeds sports poses(LSP)and MPII human pose.The experimental results show that the proposed network has better performance in human pose estimation.
基金supported by the National Natural Science Foundation of China (No. 51475460)
文摘To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by using a variable transmission ratio was developed.This method ensures that the rake angles on the indexing torus of each tooth are approximately 0°.Based on the gear meshing theory and the hourglass worm forming method,the discretization mathematical model of the rake face of a planar double enveloping worm gear hob was established by using cylindrical generating surface,and the feed parameters for machining the rake face for a variable transmission ratio were obtained.The spiral flute was simulated and the hob was machined on a four axis CNC milling machine.A contourgraph was used to measure the rake angle.The measurement results showed that the proposed method can reduce the absolute value of the rake angle on both sides of the cutting teeth,which can be used for machining the spiral flute rake face of an hourglass worm gear hob.
基金National Natural Science Foundation of China(Grant No.51875479)Innovation Fund of Postgraduate of Xihua University,China(Grant No.ycjj2019040).
文摘In gear transmission,temperature rise has a non-negligible impact on the accuracy,noise and transmission efficiency.However,there is no relevant research on the temperature rise of the anti-backlash single-roller enveloping hourglass worm(ASEHW)gear.To solve this problem,based on tribology principle and Hertz contact theory,the thermal power calculation method of the ASEHW gear was proposed for the first time and thermal analysis was carried out by Ansys software.The bulk temperature of the ASEHW gear under four different rotating speed(300 r/min,600 r/min,900 r/min,1200 r/min)is calculated.The main factors causing temperature rise of the ASEHW gear are analyzed theoretically.Meanwhile,an experimental study is performed to verify the simulation results and validate the theory methods.The theory presented in this paper provides a solution for the thermal power calculation of ASEHW gear.This research provides a theoretical basis for further optimization of ASEHW gear.
文摘Based on solid modeling, the geometry and the FE model of the hourglass worm gearing are established. By the hybrid method of FEM and penalty function, the load sharing among tooth paris and the stress of contact teeth are calculated, the contact zones and the distribution of the contact pressure are investigated. The variation of the contact states with the load is investigated by comparision of its contact patterns under different loads.
基金supported by the National Basic Research Program of China(973 Program:2013CB329004)the Fundamental Research Funds for the Central Universities
文摘The explosive growth of data volume in mobile networks makes fast online diagnose a pressing search problem. In this paper, an object-oriented detection framework with a two-step clustering, named as Hourglass Clustering, is given. Where three object parameters are chosen as Synthetical Quality of Experience(SQo E) Key Quality Indicators(KQIs) to reflect accessibility, integrality, and maintainability of networks. Then, we choose represented Key Performance Indicators(r KPIs) as cause parameters with correlation analysis. For these two kinds of parameters, a hybrid algorithm combining the self-organizing map(SOM)
基金the Doctorate Degree Program Foundation of the Ministry of Education (No. 2000061120)
文摘An approach for the contact analysis and load distribution of double-envelop hourglass worm gearing is presented, which is based on a 3-D elastic contact finite element method (FEM) model that accommodates the influence of errors and load. As compared with existing tooth contact analysis model that assumes rigidity for the contacting surfaces, the proposed model provides a more realistic analysis on the contact patterns, the distribution of contact load and transmission errors. It is also capable of exploring the influence of different errors on meshing performances, the contact deformation, the shift of the contact zone and load share among the meshing tooth-pairs under different load.
基金Supported by National Natural Science Foundation of China Key Project (50335060)
文摘Hourglass is remarkably aroused in ring rolling simulation with reduced integration element because of violent ring vibration and small contact area of ring with forming rollers. Hourglass energy can be reduced by improving mesh density. Combined approach of artificial damping and artificial stiffness can control the hourglass. A ring with rectangular section is simulated with the weight factor of artificial stiffness resistance set to 0.2. The artificial damping hourglass control coefficient is set to 0.1, and the artificial stiffness hourglass control coefficient is set to 0.001. The ratio of hourglass energy to internal energy is reduced to 2.5 percent. Compared with axial spread width test, the effectiveness of hourglass control in ring rolling simulation is verified.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.61672375 and 61170118).
文摘Recently,stacked hourglass network has shown outstanding performance in human pose estimation.However,repeated bottom-up and top-down stride convolution operations in deep convolutional neural networks lead to a significant decrease in the initial image resolution.In order to address this problem,we propose to incorporate affinage module and residual attention module into stacked hourglass network for human pose estimation.This paper introduces a novel network architecture to replace the stacked hourglass network of up-sampling operation for getting high-resolution features.We refer to the architecture as an affinage module which is critical to improve the performance of the stacked hourglass network.Additionally,we also propose a novel residual attention module to increase the supervision of up-sample process.The effectiveness of the introduced module is evaluated on standard benchmarks.Various experimental results demonstrated that our method can achieve more accurate and more robust human pose estimation results in images with complex background.
基金This work was supported by the National Natural Science Foundation of China(Grant No.11902096)the China Postdoctoral Science Foundation(Grant No.2020M670886)the Heilongjiang Postdoctoral Fund(Grant No.LBH-Z19010)。
文摘In this article,the design of the hourglass truss sandwich structure is improved by optimizing the number of layers to enhance the compressive strength of both the core and the face sheet and then its mechanical performance. The hourglass truss structures characterized by three different numbers of layers are manufactured using an interlocking and vacuum brazing method. The effect of the layer number of the hourglass core panels on their out-of-plane compression and in-plane compression performance is investigated,and the results from calculations and experiments are in reasonable agreement. The results show that as the layer number of the hourglass core increases,the out-of-plane compressive strengths show little change,but their energy absorption properties are effectively increased. The in-plane compressive failure mechanism maps are constructed,and the specimens are designed to examine the local elastic and inelastic buckling failure modes of the face sheets. The results suggest that as the number of layers of the hourglass core increases,its maximum in-plane compressive load increases. The maximum in-plane compressive loads of the two-layer hourglass truss panels are 57%–70% higher than those of the single-layer panels. It can also be concluded that the out-of-plane and in-plane compression mechanical properties of the multilayer hourglass truss outperform those of the pyramidal truss. Furthermore,the number of layers of the hourglass core is optimized in consideration of both mechanical properties and fabrication cost.
