This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the acc...This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.展开更多
The study aimed to develop efficient techniques with different novel graft structures to enhance the treatment of acetabular bone deficiency.The inhomogeneous material properties Finite Element Analysis(FEA)model was ...The study aimed to develop efficient techniques with different novel graft structures to enhance the treatment of acetabular bone deficiency.The inhomogeneous material properties Finite Element Analysis(FEA)model was reconstructed according to computed tomography images based on a healthy patient without any peri-acetabular bony defect according to the American Academy of Orthopedic Surgeons(AAOS).The FEA model of acetabular bone deficiency was performed to simulate and evaluate the mechanical performances of the grafts in different geometric structures,with the use of fixation implants(screws),along with the stress distribution and the relative micromotion of graft models.The stress distribution mainly concentrated on the region of contact of the screws and superolateral bone.Among the different structures,the mortise-tenone structure provided better relative micromotion,with suitable biomechanical property even without the use of screws.The novel grafting structures could provide sufficient biomechanical stability and bone remodeling,and the mortise-tenone structure is the optimal treatment option for acetabulum reconstruction.展开更多
Junior English for China’ is based on the ’Five-Step’ teachingmethod: Revision, Presentation, Drilling, Practice, Consolidation. Each step has itsown particular methodology and requires the teacher to adopt a certa...Junior English for China’ is based on the ’Five-Step’ teachingmethod: Revision, Presentation, Drilling, Practice, Consolidation. Each step has itsown particular methodology and requires the teacher to adopt a certain role. Thispaper is a discussion of the "Five-Step Method".展开更多
传统水煮法虽操作简单,但受人为影响较大,缺乏定量分析评价指标。为有效测试沥青与集料界面的黏附性能,通过图像处理技术引入剥落率定量评价指标,对传统水煮法进行修正,采用Image Pro Plus(IPP)软件定量分析沸煮过程中沥青剥落率,并对70...传统水煮法虽操作简单,但受人为影响较大,缺乏定量分析评价指标。为有效测试沥青与集料界面的黏附性能,通过图像处理技术引入剥落率定量评价指标,对传统水煮法进行修正,采用Image Pro Plus(IPP)软件定量分析沸煮过程中沥青剥落率,并对70#基质沥青、水激活冷拌冷铺液体沥青与玄武岩集料的黏附特性开展研究。结果表明:1)同一试验条件下,70#基质沥青平均剥落率达71%,水激活冷拌冷铺沥青为44%,说明水激活冷拌冷铺沥青表现出显著优越的黏附性;2)修正水煮法能定量测试沥青-集料界面黏附性,可为沥青-集料界面黏附性评价提供依据,可用于水激活冷拌冷铺沥青混合料耐久性设计。展开更多
基金supported by the Advance Research Project of Civil Aerospace Technology(Grant No.D020304)National Nat-ural Science Foundation of China(Grant Nos.52205257 and U22B2083).
文摘This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.
基金supported and funded by the following grants:National Natural Science Foundation of China[Grant Numbers 82072456 and 81802174]National Key R&D Program of China[Grant Number.2018YFB1105100]+7 种基金Bethune plan of Jilin University[Grant Number 419161900014]Wu Jieping Medical Foundation[3R119C073429]Department of Science and Technology of Jilin Province,P.R.C.[Grant Numbers 20200404202YY and 20200201453JC]Department of Finance in Jilin province[Grant Numbers 2019SCZT046,2020SCZT037]undergraduate teaching reform research project of Jilin University[Grant Number 4Z2000610852]key training plan for outstanding young teachers of Jilin University[Grant Number 419080520253]Jilin Province Development and Reform Commission,P.R.C.[Grant Number 2018C010]Natural Science Foundation of Jilin Province[Grant Number 20200201345JC].
文摘The study aimed to develop efficient techniques with different novel graft structures to enhance the treatment of acetabular bone deficiency.The inhomogeneous material properties Finite Element Analysis(FEA)model was reconstructed according to computed tomography images based on a healthy patient without any peri-acetabular bony defect according to the American Academy of Orthopedic Surgeons(AAOS).The FEA model of acetabular bone deficiency was performed to simulate and evaluate the mechanical performances of the grafts in different geometric structures,with the use of fixation implants(screws),along with the stress distribution and the relative micromotion of graft models.The stress distribution mainly concentrated on the region of contact of the screws and superolateral bone.Among the different structures,the mortise-tenone structure provided better relative micromotion,with suitable biomechanical property even without the use of screws.The novel grafting structures could provide sufficient biomechanical stability and bone remodeling,and the mortise-tenone structure is the optimal treatment option for acetabulum reconstruction.
文摘Junior English for China’ is based on the ’Five-Step’ teachingmethod: Revision, Presentation, Drilling, Practice, Consolidation. Each step has itsown particular methodology and requires the teacher to adopt a certain role. Thispaper is a discussion of the "Five-Step Method".
文摘传统水煮法虽操作简单,但受人为影响较大,缺乏定量分析评价指标。为有效测试沥青与集料界面的黏附性能,通过图像处理技术引入剥落率定量评价指标,对传统水煮法进行修正,采用Image Pro Plus(IPP)软件定量分析沸煮过程中沥青剥落率,并对70#基质沥青、水激活冷拌冷铺液体沥青与玄武岩集料的黏附特性开展研究。结果表明:1)同一试验条件下,70#基质沥青平均剥落率达71%,水激活冷拌冷铺沥青为44%,说明水激活冷拌冷铺沥青表现出显著优越的黏附性;2)修正水煮法能定量测试沥青-集料界面黏附性,可为沥青-集料界面黏附性评价提供依据,可用于水激活冷拌冷铺沥青混合料耐久性设计。
