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Zhiyi Wu,Yumei Wen,Ping Li,Jin Yang,Xianzhi Dai 한국자기학회 2011 Journal of Magnetics Vol.16 No.2
The magnetostrictive material is magnetized in magnetic field and produces a nonuniform demagnetizing field inside and outside it. The demagnetization is decided by the permeability of magnetostrictive material and its size. The magnetoelectric performances are determined by the synthesis of the applied and demagnetizing fields. An analytical model is proposed to predict the magnetoelectric voltage coefficient (MEVC) of magnetostrictive/piezoelectric laminate composite using equivalent circuit method, in which the nonuniform demagnetizing field is taken into account. The theoretical and experimental results indicate that the MEVC is positively connected with the permeability and the piezomagnetic coefficient of magnetostrictive material. To obtain the maximum MEVC, both the permeability and the piezomagnetic coefficient of magnetostrictive material should be taken into account in selecting the suitable magnetostrictive material.
Zhiyi Tu,Liangliang Chen,Qiong Li,Xiaoguang Jin,Jiaju Wu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12
This paper proposes a new design method for sleeve thickness and interference based on a multi-dimensional visualization algorithm that overcomes difficulties in solving. The contact pressure between the rotor core and the permanent magnet, the maximum equivalent Mises stress of the permanent magnet, and the maximum equivalent Mises stress of the sleeve are selected as the optimization objectives. The stress limit strength of the permanent magnet and sleeve are taken as constraints, and the sleeve thickness and interference are selected as decision variables. Then the multi-dimensional visualization algorithm is used to find the optimal region of sleeve thickness and interference. Finally, the design solution is validated by the finite element method. The results show that the design method proposed in this paper can obtain the optimal region of sleeve thickness and interference with the characteristics of a simple solution process and intuitive results.
Comparison of Deformation Behavior of Saturated Sand under Constant and Variable Deviatoric Stress
Zhiyi Zhao,Gang Deng,Yunshan Han,Zhaopeng Zhang,Yanli Dong,Ying Gao 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.3
The cyclic triaxial tests were carried out on Fujian standard sand under two stress paths, the constant deviatoric stress path (CDS) and constant stress-ratio path (variable deviatoric stress, VDS), and the influence of cyclic deviatoric stress on the development characteristics of saturated sand was preliminarily discussed. Under the condition of the same consolidation stress state and amplitude of cyclic spherical stress, the amplitude of deviatoric stress under the two stress paths was different. The test results indicated that cyclic deviatoric stress had significant effect on the volumetric and shear strain in soil. When the consolidation deviatoric stress was relatively small, the volumetric and shear strain curves under these two stress paths almost coincided. However, the cyclic deviatoric stress had a stronger effect with an increase in the consolidation deviatoric stress. During the loading and unloading stages, the slope of the volumetric strain curve under the VDS path was smaller than that under the CDS path. The accumulated volumetric strain under the VDS path was greater than that under the CDS path. In the loading stage, the growth rate of shear strain under the VDS path was greater than that under the CDS path, but the opposite relationship was observed in the unloading stage. The presence of cyclic deviatoric stress accelerated or slowed down the accumulation of shear strain. These phenomena were related to the positional relationship between the stress state of soil and the critical state line.
Zhiyi Li,You Du,Yiwei Zhao,Guanfeng Lin,Haoran Zhang,Chenkai Li,Xiaohan Ye,Yang Yang,Shengru Wang,Jianguo Zhang 대한척추신경외과학회 2023 Neurospine Vol.20 No.4
Objective: To compare the radiological outcomes in Lenke 5C type patients whose lowest instrumented vertebra (LIV) was L3 or L4 in a case-match study. Methods: We conducted a retrospective case-match study and included 82 patients in the study. Radiological results before surgery, after surgery, and at last follow-up were recorded and analyzed in the L3 and L4 groups. Results: After matching the age, Risser’s sign, sex, and main Cobb, 41 pairs of patients were enrolled in our study. The total fusion segments in the L3 group (median [interquartile range]: 5.0 [6.0–5.0]) were shorter than those in the L4 group (6.0 [6.5–6.0]). The main curve was significantly corrected after surgery in both groups, and was comparable at the last followup between groups. In addition, according to the results of Fisher precision probability test, there was no significant difference of coronal or sagittal imbalance between the 2 groups at the 2-year follow-up. Conclusion: The correction in coronal and sagittal planes in L3 group and L4 group remains similar. On account of more motion segments, L3 could be an ideal choice as LIV in moderate Lenke 5C type AIS. Long-term follow-up is needed to evaluate the effect of larger compensatory lumbar-sacral curve when stopping at L3.
An improved Big Bang-Big Crunch algorithm for structural damage detection
Zhiyi Yin,Jike Liu,Wei-Li Luo,Zhongrong Lu 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6
The Big Bang-Big Crunch (BB-BC) algorithm is an effective global optimization technique of swarm intelligence with drawbacks of being easily trapped in local optimal results and of converging slowly. To overcome these shortages, an improved BB-BC algorithm (IBB-BC) is proposed in this paper with taking some measures, such as altering the reduced form of exploding radius and generating multiple mass centers. The accuracy and efficiency of IBB-BC is examined by different types of benchmark test functions. The IBB-BC is utilized for damage detection of a simply supported beam and the European Space Agency structure with an objective function established by structural frequency and modal data. Two damage scenarios are considered: damage only existed in stiffness and damage existed in both stiffness and mass. IBB-BC is also validated by an existing experimental study. Results demonstrated that IBB-BC is not trapped into local optimal results and is able to detect structural damages precisely even under measurement noise.
Extracting Topics from Texts Based on Situations
( Ma Zhiyi ),( Zhan Xuegong ),( Yao Tianshun ) 한국언어정보학회 1996 국제 워크샵 Vol.1996 No.-
To understand text, we must relate it with specified situations. This paper, on the basis of such an idea, discusses how the things that a text describes and the situation that the text relates to are expressed in a computer and how the topic of a text is extracted.
Topology optimization of reinforced concrete structure using composite truss-like model
Yang Zhiyi,Zhou Kemin,Qiao Shengfang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.1
Topology optimization of steel and concrete composite based on truss-like material model is studied in this paper. First, the initial design domain is filled with concrete, and the steel is distributed in it. The problem of topology optimization is to minimize the volume of steel material and solved by full stress method. Then the optimized steel and concrete composite truss-like continuum is obtained. Finally, the distribution of steel material is determined based on the optimized truss-like continuum. Several numerical results indicate the numerical instability and rough boundary are settled. And more details of manufacture and construction can be presented based on the truss-like material model. Hence, the truss-like material model of steel and concrete is efficient to establish the distribution of steel material in concrete.