The plastic gear is widely used in agricultural equipment,electronic products,aircraft,and other fields because of its light weight,corrosion resistance,and self-lubrication ability.However,it has a limited range of w...The plastic gear is widely used in agricultural equipment,electronic products,aircraft,and other fields because of its light weight,corrosion resistance,and self-lubrication ability.However,it has a limited range of working conditions due to the low modulus and thermal deformation of the material,especially in high-speed and heavy-duty situations.A compensation modification method(CMM)is proposed in this paper to restrain the heat production of the plastic gear tooth surface by considering the meshing deformation,and the corresponding modification formulas are derived.Improving the position of the maximum contact pressure(CP)and the relative sliding velocity(RSV)of the tooth surface resulted in a 30%lower steady-state temperature rise of the modified plastic gear tooth surface than that of the unmodified plastic gear.Meanwhile,the temperature rise of plastic gear with CMM is reduced by 19%compared with the traditional modification of removal material.Then,the influences of modification index and the segment number of modification on the meshing characteristics of plastic gear with CMM are discussed,such as maximum CP and steadystate temperature rise,RSV,transmission error,meshing angle,and contact ratio.A smaller segment number and modification index are beneficial to reduce the temperature rise of plastic gear with CMM.Finally,an experiment is carried out to verify the theoretical analysis model.展开更多
According to spatial conjugate principle and theory of elastic contact, a method to pre-control transmission properties and contact mark of point meshing gear is presented, while the deformation of tooth surface is un...According to spatial conjugate principle and theory of elastic contact, a method to pre-control transmission properties and contact mark of point meshing gear is presented, while the deformation of tooth surface is under consideration. A new approach to improve the quality of spiral bevel gear is illustrated emphatically.展开更多
Alcohol influences human health condition by starving red blood cells (RBCs) of oxygen, which results in poor blood circulation. Starved RBCs clump together and restrict blood flow, especially in capillaries. In this ...Alcohol influences human health condition by starving red blood cells (RBCs) of oxygen, which results in poor blood circulation. Starved RBCs clump together and restrict blood flow, especially in capillaries. In this study, a finite element method-based moving mesh technique was applied to simulate the motion and deformation of a single RBC under different flow conditions. A 2-D model of a single RBC floating in plasma-alcohol solution was created using Arbitrary Lagrangian-Eulerian (ALE) method with moving mesh for a fluid structure interaction problem. Cell deformability and stability were studied in an alcoholic plasma solution at different fluid flow conditions. Poor blood circulation was observed with RBC tending to rotate and oscillate at low flow rates. Moreover, RBC exhibited a parachute shape while moving without oscillation, which indicated improved micro-circulation at increased flow rates. In both cases, RBC exhibited a parachute shape while moving through micro-channel at increased flow rates. The simulation also showed the significant increase of RBC deformability with the increasing viscosity of plasma as a result of alcohol presence in blood.展开更多
Objective To investigate the effect of invisible full-thickness mesh skin graft in the treatment of scar contracture deformity of the dorsal hand.Methods From January 2016 to February 2019,25 patients with cicatricial...Objective To investigate the effect of invisible full-thickness mesh skin graft in the treatment of scar contracture deformity of the dorsal hand.Methods From January 2016 to February 2019,25 patients with cicatricial contracture deformity of dorsal hand admitted to our hospital underwent full thickness skin graft.During the operation,the scar healed completely and the superficial fascia remained intact.The wound surface was transplanted with invisible mesh full thickness skin graft.The survival of the skin graft and the recovery of hand function and appearance in the later period were observed after the operation.Results The skin grafts of 20 patients survived with high quality,3 cases had partial epidermis exfoliation,and 2 cases had partial epidermis scattered in blisters.After intensive dressing change,all wounds healed and no complications occurred after the operation.The hand function and appearance of the patients were obviously improved.Conclusion The application of full thickness skin graft to correct scar deformity has the advantages of good functional and appearance recovery and difficult postoperative contracture.Invisible full-thickness mesh skin graft is one of the ideal methods to correct scar contracture deformity of the dorsal hand.展开更多
The traditional pipeline for non-rigid registration is to iteratively update the correspondence and alignment such that the transformed source surface aligns well with the target surface.Among the pipeline,the corresp...The traditional pipeline for non-rigid registration is to iteratively update the correspondence and alignment such that the transformed source surface aligns well with the target surface.Among the pipeline,the correspondence construction and iterative manner are key to the results,while existing strategies might result in local optima.In this paper,we adopt the widely used deformation graph-based representation,while replacing some key modules with neural learning-based strategies.Specifically,we design a neural network to predict the correspondence and its reliability confidence rather than the strategies like nearest neighbor search and pair rejection.Besides,we adopt the GRU-based recurrent network for iterative refinement,which is more robust than the traditional strategy.The model is trained in a self-supervised manner and thus can be used for arbitrary datasets without ground-truth.Extensive experiments demonstrate that our proposed method outperforms the state-of-the-art methods by a large margin.展开更多
AIM To evaluate the clinical and radiographic results of patients with complicated infectious spondylitis treated with single-stage anterior debridement and reconstruction using tantalum mesh cage(TaMC) followed by im...AIM To evaluate the clinical and radiographic results of patients with complicated infectious spondylitis treated with single-stage anterior debridement and reconstruction using tantalum mesh cage(TaMC) followed by immediate instrumentation.METHODS Single-stage radical debridement and subsequent reconstruction with TaMC instead of autograft or allograft were performed to treat 20 patients with spinal deformity or instability due to complicated infectious spondylitis. Clinical outcomes were assessed by careful physical examination and regular serological tests to determine the infection control. In addition, the visual analog score(VAS), neurologic status, length of vertebral body reconstruction, and the correction of sagittal Cobb angle on radiography were recorded and compared before and after surgery. The conditions of the patients were evaluated based on the modified Brodsky's criteria.RESULTS The average VAS score significantly decreased after the surgery(from 7.4 ± 0.8 to 3.3 ± 0.8, P < 0.001). The average Cobb angle correction was 14.9 degrees. The neurologic status was significantly improved after the surgery(P = 0.003). One patient experienced refractory infection and underwent additional debridement. Eighteen patients achieved good outcome based on the modified Brodsky's criteria and significant improvement after the surgery(P < 0.001). No implant breakage orTaMC dislodgement was found during at least 24 mo of follow-up.CONCLUSION Single-stage anterior debridement and reconstruction with TaMC followed by immediate instrumentation could be an alternative method to manage the patients with spinal deformity or instability due to complicated infectious spondylitis.展开更多
A mutual information-based non-rigid medical image registration algorithm is presented. An approximate function of Hanning windowed sinc is used as kernel function of partial volume (PV) interpolation to estimate the ...A mutual information-based non-rigid medical image registration algorithm is presented. An approximate function of Hanning windowed sinc is used as kernel function of partial volume (PV) interpolation to estimate the joint histogram, which is the key to calculating the mutual information. And a new method is proposed to compute the gradient of mutual information with respect to the model parameters. The transformation of object is modeled by a free-form deformation (FFD) based on B-splines. The experiments on 3D synthetic and real image data show that the algorithm can converge at the global optimum and restrain the emergency of local extreme.展开更多
An exact-designed mesh shape with favorable surface accuracy is of practical significance to the performance of large cable-network antenna reflectors. In this study, a novel design approach that could guide the gener...An exact-designed mesh shape with favorable surface accuracy is of practical significance to the performance of large cable-network antenna reflectors. In this study, a novel design approach that could guide the generation of exact spatial parabolic mesh configurations of such reflector was proposed. By incorporating the traditional force density method with the standard finite element method, this proposed approach had taken the deformation effects of flexible ring truss supports into consideration, and searched for the desired mesh shapes that can satisfy the requirement that all the free nodes are exactly located on the objective paraboloid. Compared with the conventional design method,a remarkable improvement of surface accuracy in the obtained mesh shapes had been demonstrated by numerical examples. The present work would provide a helpful technical reference for the mesh shape design of such cable-network antenna reflector in engineering practice.展开更多
Traditional variation analysis methods are not applicable to non-rigid assemblies due to possible part deformation during the assembly process. This paper presents the use of finite element methods to simulate assembl...Traditional variation analysis methods are not applicable to non-rigid assemblies due to possible part deformation during the assembly process. This paper presents the use of finite element methods to simulate assembly deformation. The relationship between the parts’ variation and the variation of the key points in final assembly for quality control is set up by calculating the spring back deformation after assembly. Moreover, the optimization method for non-rigid assembly variations based on finite element analysis is presented. The optimal objective is to reduce the manufacturing cost. The approach is implemented by using ANSYS and MATLAB. The test example shows that the proposed method is effective and applicable.展开更多
A mixed finite element solution of contact stresses in meshing gears is investigated with the consideration of coupled thermo-elastic deformation and impact behavior. A simulation procedure of finite element solution ...A mixed finite element solution of contact stresses in meshing gears is investigated with the consideration of coupled thermo-elastic deformation and impact behavior. A simulation procedure of finite element solution of meshing gears is developed. The versatility of the procedure for both numerical accuracy and computational efficiency is verified by numerical analysis of meshing gear teeth.展开更多
基金supported by the Core Technology Application of Hubei Agricultural Machinery Equipment,China(Grant No.HBSNYT202221).
文摘The plastic gear is widely used in agricultural equipment,electronic products,aircraft,and other fields because of its light weight,corrosion resistance,and self-lubrication ability.However,it has a limited range of working conditions due to the low modulus and thermal deformation of the material,especially in high-speed and heavy-duty situations.A compensation modification method(CMM)is proposed in this paper to restrain the heat production of the plastic gear tooth surface by considering the meshing deformation,and the corresponding modification formulas are derived.Improving the position of the maximum contact pressure(CP)and the relative sliding velocity(RSV)of the tooth surface resulted in a 30%lower steady-state temperature rise of the modified plastic gear tooth surface than that of the unmodified plastic gear.Meanwhile,the temperature rise of plastic gear with CMM is reduced by 19%compared with the traditional modification of removal material.Then,the influences of modification index and the segment number of modification on the meshing characteristics of plastic gear with CMM are discussed,such as maximum CP and steadystate temperature rise,RSV,transmission error,meshing angle,and contact ratio.A smaller segment number and modification index are beneficial to reduce the temperature rise of plastic gear with CMM.Finally,an experiment is carried out to verify the theoretical analysis model.
文摘According to spatial conjugate principle and theory of elastic contact, a method to pre-control transmission properties and contact mark of point meshing gear is presented, while the deformation of tooth surface is under consideration. A new approach to improve the quality of spiral bevel gear is illustrated emphatically.
文摘Alcohol influences human health condition by starving red blood cells (RBCs) of oxygen, which results in poor blood circulation. Starved RBCs clump together and restrict blood flow, especially in capillaries. In this study, a finite element method-based moving mesh technique was applied to simulate the motion and deformation of a single RBC under different flow conditions. A 2-D model of a single RBC floating in plasma-alcohol solution was created using Arbitrary Lagrangian-Eulerian (ALE) method with moving mesh for a fluid structure interaction problem. Cell deformability and stability were studied in an alcoholic plasma solution at different fluid flow conditions. Poor blood circulation was observed with RBC tending to rotate and oscillate at low flow rates. Moreover, RBC exhibited a parachute shape while moving without oscillation, which indicated improved micro-circulation at increased flow rates. In both cases, RBC exhibited a parachute shape while moving through micro-channel at increased flow rates. The simulation also showed the significant increase of RBC deformability with the increasing viscosity of plasma as a result of alcohol presence in blood.
文摘Objective To investigate the effect of invisible full-thickness mesh skin graft in the treatment of scar contracture deformity of the dorsal hand.Methods From January 2016 to February 2019,25 patients with cicatricial contracture deformity of dorsal hand admitted to our hospital underwent full thickness skin graft.During the operation,the scar healed completely and the superficial fascia remained intact.The wound surface was transplanted with invisible mesh full thickness skin graft.The survival of the skin graft and the recovery of hand function and appearance in the later period were observed after the operation.Results The skin grafts of 20 patients survived with high quality,3 cases had partial epidermis exfoliation,and 2 cases had partial epidermis scattered in blisters.After intensive dressing change,all wounds healed and no complications occurred after the operation.The hand function and appearance of the patients were obviously improved.Conclusion The application of full thickness skin graft to correct scar deformity has the advantages of good functional and appearance recovery and difficult postoperative contracture.Invisible full-thickness mesh skin graft is one of the ideal methods to correct scar contracture deformity of the dorsal hand.
基金supported by National Natural Science Foundation of China(No.62122071)the Youth Innovation Promotion Association CAS(No.2018495)“the Fundamental Research Funds for the Central Universities”(No.WK3470000021).
文摘The traditional pipeline for non-rigid registration is to iteratively update the correspondence and alignment such that the transformed source surface aligns well with the target surface.Among the pipeline,the correspondence construction and iterative manner are key to the results,while existing strategies might result in local optima.In this paper,we adopt the widely used deformation graph-based representation,while replacing some key modules with neural learning-based strategies.Specifically,we design a neural network to predict the correspondence and its reliability confidence rather than the strategies like nearest neighbor search and pair rejection.Besides,we adopt the GRU-based recurrent network for iterative refinement,which is more robust than the traditional strategy.The model is trained in a self-supervised manner and thus can be used for arbitrary datasets without ground-truth.Extensive experiments demonstrate that our proposed method outperforms the state-of-the-art methods by a large margin.
文摘AIM To evaluate the clinical and radiographic results of patients with complicated infectious spondylitis treated with single-stage anterior debridement and reconstruction using tantalum mesh cage(TaMC) followed by immediate instrumentation.METHODS Single-stage radical debridement and subsequent reconstruction with TaMC instead of autograft or allograft were performed to treat 20 patients with spinal deformity or instability due to complicated infectious spondylitis. Clinical outcomes were assessed by careful physical examination and regular serological tests to determine the infection control. In addition, the visual analog score(VAS), neurologic status, length of vertebral body reconstruction, and the correction of sagittal Cobb angle on radiography were recorded and compared before and after surgery. The conditions of the patients were evaluated based on the modified Brodsky's criteria.RESULTS The average VAS score significantly decreased after the surgery(from 7.4 ± 0.8 to 3.3 ± 0.8, P < 0.001). The average Cobb angle correction was 14.9 degrees. The neurologic status was significantly improved after the surgery(P = 0.003). One patient experienced refractory infection and underwent additional debridement. Eighteen patients achieved good outcome based on the modified Brodsky's criteria and significant improvement after the surgery(P < 0.001). No implant breakage orTaMC dislodgement was found during at least 24 mo of follow-up.CONCLUSION Single-stage anterior debridement and reconstruction with TaMC followed by immediate instrumentation could be an alternative method to manage the patients with spinal deformity or instability due to complicated infectious spondylitis.
基金Supported bythe National Basic Research Programof China ("973"Program) (No2003CB716103)Key Project of Shanghai Scienceand Technology Committee(No05DZ19509)
文摘A mutual information-based non-rigid medical image registration algorithm is presented. An approximate function of Hanning windowed sinc is used as kernel function of partial volume (PV) interpolation to estimate the joint histogram, which is the key to calculating the mutual information. And a new method is proposed to compute the gradient of mutual information with respect to the model parameters. The transformation of object is modeled by a free-form deformation (FFD) based on B-splines. The experiments on 3D synthetic and real image data show that the algorithm can converge at the global optimum and restrain the emergency of local extreme.
文摘An exact-designed mesh shape with favorable surface accuracy is of practical significance to the performance of large cable-network antenna reflectors. In this study, a novel design approach that could guide the generation of exact spatial parabolic mesh configurations of such reflector was proposed. By incorporating the traditional force density method with the standard finite element method, this proposed approach had taken the deformation effects of flexible ring truss supports into consideration, and searched for the desired mesh shapes that can satisfy the requirement that all the free nodes are exactly located on the objective paraboloid. Compared with the conventional design method,a remarkable improvement of surface accuracy in the obtained mesh shapes had been demonstrated by numerical examples. The present work would provide a helpful technical reference for the mesh shape design of such cable-network antenna reflector in engineering practice.
基金Supported by the Natural Science Foundation of China (No. 50205028) and the Natural Science Foundation of Chongqing City (No. 2005BB2022 ).
文摘Traditional variation analysis methods are not applicable to non-rigid assemblies due to possible part deformation during the assembly process. This paper presents the use of finite element methods to simulate assembly deformation. The relationship between the parts’ variation and the variation of the key points in final assembly for quality control is set up by calculating the spring back deformation after assembly. Moreover, the optimization method for non-rigid assembly variations based on finite element analysis is presented. The optimal objective is to reduce the manufacturing cost. The approach is implemented by using ANSYS and MATLAB. The test example shows that the proposed method is effective and applicable.
文摘A mixed finite element solution of contact stresses in meshing gears is investigated with the consideration of coupled thermo-elastic deformation and impact behavior. A simulation procedure of finite element solution of meshing gears is developed. The versatility of the procedure for both numerical accuracy and computational efficiency is verified by numerical analysis of meshing gear teeth.
