A novel probabilistic feasible region method for reliability-based design optimization with varying standard deviation

Zihao Wu,Zhenzhong Chen,Ge Chen,Xiaoke Li,Chen Jiang,Xuehui Gan,Haobo Qiu,Liang Gao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

An effective method for reliability-based design optimization (RBDO) problems taking uncertainties into account is the probabilistic feasible region (PFR) approach. The PFR approach is built around the fixed nature of the standard deviation in general RBDO problems. Therefore, the accuracy of the PFR approach will be affected when dealing with RBDO problems with varying standard deviation. To improve the accuracy of PFR method in solving the RBDO problems with varying standard deviation, a novel probabilistic feasible region strategy considering varying standard deviations (PFR-vstd) approach is suggested in this paper. In place of the initial probabilistic feasible region in standard normal space, a new probabilistic feasible region is established in original design space in this novel approach. The results of four applications demonstrate the high accuracy and sufficient efficiency of PFR-vstd method. The findings demonstrate that PFR-vstd method is capable of accurately resolving RBDO problems with varying standard deviation.

An efficient time-variant reliability-based design optimization method based on probabilistic feasible region

Zihao Wu,Zhenzhong Chen,Ge Chen,Xiaoke Li,Chen Jiang,Xuehui Gan,Haobo Qiu,Liang Gao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

Time-variant reliability-based design optimization (T-RBDO) issues are probabilistic design problems that assess the dependability of the design across time. The engineering situation is most closely resembled by it. The approaches to resolving T-RBDO problems, nevertheless, are convoluted and time-consuming. In this paper, an effective strategy for solving RBDO issues are extended to resolving TRBDO problems in order to increase efficiency. To solve T-RBDO challenges, the time-variant probabilistic feasible region (T-PFR) approach, which is based on the PFR method for resolving RBDO issues, was presented. The idea of the equivalent inverse most probable point (EIMPP) is put out in this methodology. Based on the EIMPP, the probabilistic feasible region is likewise developed for time-variant constraints. The effective tactic of the proposed method is to identify the non-active time-variant constraints using the probabilistic feasible region and to forego conducting time reliability analysis on them. Three mathematics and two engineering issues demonstrate that the suggested solution is viable and effective.

Sparse decision feedback equalization for underwater acoustic channel based on minimum symbol error rate

Wang Zhenzhong,Chen Fangjiong,Yu Hua,Shan Zhilong 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1

Underwater Acoustic Channels (UAC) have inherent sparse characteristics. The traditional adaptive equalization techniques do not utilize this feature to improve the performance. In this paper we consider the Variable Adaptive Subgradient Projection (V-ASPM) method to derive a new sparse equalization algorithm based on the Minimum Symbol Error Rate (MSER) criterion. Compared with the original MSER algorithm, our proposed scheme adds sparse matrix to the iterative formula, which can assign independent step-sizes to the equalizer taps. How to obtain such proper sparse matrix is also analyzed. On this basis, the selection scheme of the sparse matrix is obtained by combining the variable step-sizes and equalizer sparsity measure. We call the new algorithm Sparse-Control Proportional-MSER (SC-PMSER) equalizer. Finally, the proposed SC-PMSER equalizer is embedded into a turbo receiver, which perform turbo decoding, Digital Phase-Locked Loop (DPLL), time-reversal receiving and multi-reception diversity. Simulation and real-field experimental results show that the proposed algorithm has better performance in convergence speed and Bit Error Rate (BER).

Research on Automatic Compensation Technology for Eccentricity of Grinding Wheel

Shi-Ping Chen,Zhenzhong Wang,Hui Yu,Long-Qiao Lin 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.8

To ensure the installation precision of grinding wheel in precision grinding, the attitude of spindle axis must be adjusted to coincide with the geometric center of grinding wheel before the process. A special device that combined with piezoelectric actuators with threedegrees- of-freedom is designed. The corresponding method of automatic compensation technology for eccentricity of grinding wheel is developed. In order to calculate accurately eccentric angle and the eccentricity of the grinding wheel, high accuracy detection algorithm for eccentric signal of grinding wheel is given by the principle of rotary roundness error minimization firstly. Then a decomposition algorithm is proposed to decompose the eccentricity into three directions and the eccentricity can be eliminated by the coordinated control of the three piezoelectric actuators. Experimental results show that the average accuracy of the system is about 5.48 μm. Compared with the sine fitting algorithm, the algorithm presented for adjusting the eccentricity of grinding wheel in this paper is more stable and the accuracy is improved by about 78.2%, which shows that the proposed approach works successfully.

Modification of tool influence function for bonnet polishing tool based on analysis of interfacial contact state

Ri Pan,Xiangxiang Zhu,Zhenzhong Wang,Dongju Chen,Shuting Ji,Jinwei Fan,Rui Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

The polishing mechanism of bonnet polishing (BP) and the tool influence function (TIF) of bonnet tool have been widely studied. However, most of current studies pay little attention to the influence of polishing slurry on the BP mechanism as well as TIF. This study proposes that the interfacial contact state between the polishing tool and the workpiece is in a mixed lubrication state, subsequently the BP mechanism is further explored. It is found that the workpiece material is removed by polishing pad and abrasives. The polishing slurry is not directly involved in workpiece removal, but shares the normal pressure of the polishing tool on workpiece, which affects material removal. Based on the above mechanism, the TIF removal prediction model is established and verified by experiments. The results show that the maximum error of the model prediction value is quiet small, which verifies the model. Moreover, compared with Preston model and the previous model, which ignored the influence of the fluid, the average prediction error of the model in this paper when D 0 = 20 mm is 6.38 %, while the previous model and Preston model are 11.21 % and 49.10 %, respectively. Which illustrates the model in this paper has higher accuracy.

Multi-Epitope Fusion Protein Eg mefAg-1 as a Serodiagnostic Candidate for Cystic Echinococcosis in Sheep

Liu Tianli,Wang Xifeng,Tian Zhenzhong,Wang Lixia,Zhang Xingxing,Qiao Jun,Meng Qingling,Gong Shasha,Chen Ying,Cai Xuepeng 대한기생충학ㆍ열대의학회 2019 The Korean Journal of Parasitology Vol.57 No.1

Cystic echinococcosis (CE) in sheep is a hazardous zoonotic parasitic disease that is caused by Echinococcus granulosus (Eg). At present, serological test is an important diagnostic method for Eg infection in domestic animals. Here, a fusion protein Eg mefAg-1 harboring 8 dominant B-cell epitopes of Eg such as antigen B, tetraspanin 1, tetraspanin 6, reticulon and Eg95 was produced in E. coli and evaluated for CE in sheep by indirect ELISA. Eg mefAg-1 showed in ELI- SA a high sensitivity (93.41%) and specificity (99.31%), with a coincidence rate of 97.02%. Overall, it is suggested that the Eg mefAg-1 could be a potential antigen candidate for CE serodiagnosis in sheep.

Multi-scale heat conduction models with improved equivalent thermal conductivity of TRISO fuel particles for FCM fuel

Wang Mouhao,Bu Shanshan,Zhou Bing,Li Zhenzhong,Chen Deqi 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Fully Ceramic Microencapsulated (FCM) fuel is emerging advanced fuel material for the future nuclear reactors. The fuel pellet in the FCM fuel is composed of matrix and a large number of TRistructural- ISOtopic (TRISO) fuel particles which are randomly dispersed in the SiC matrix. The minimum layer thickness in a TRISO fuel particle is on the order of 105 m, and the length of the FCM pellet is on the order of 102 m. Hence, the heat transfer in the FCM pellet is a multi-scale phenomenon. In this study, three multi-scale heat conduction models including the Multi-region Layered (ML) model, Multi-region Non-layered (MN) model and Homogeneous model for FCM pellet were constructed. In the ML model, the random distributed TRISO fuel particles and coating layers are completely built. While the TRISO fuel particles with coating layers are homogenized in the MN model and the whole fuel pellet is taken as the homogenous material in the Homogeneous model. Taking the results by the ML model as the benchmark, the abilities of the MN model and Homogenous model to predict the maximum and average temperature were discussed. It was found that the MN model and the Homogenous model greatly underestimate the temperature of TRISO fuel particles. The reason is mainly that the conventional equivalent thermal conductivity (ETC) models do not take the internal heat source into account and are not suitable for the TRISO fuel particle. Then the improved ETCs considering internal heat source were derived. With the improved ETCs, the MN model is able to capture the peak temperature as well as the average temperature at a wide range of the linear powers (165 W/ cm~ 415 W/cm) and the packing fractions (20%e50%). With the improved ETCs, the Homogenous model is better to predict the average temperature at different linear powers and packing fractions, and able to predict the peak temperature at high packing fractions (45%e50%).

Ultrafast dynamics control on ablation of Cu using shaped femtosecond pulse trains

Deng Jiannan,Qi Hongxia,Liu Xinyi,Li Xiaoyi,Tong Qiunan,Lian Zhenzhong,Li Juan,Bo Jinqiu,Fei Dehou,Chen Zhou,Hu Zhan 한국물리학회 2021 Current Applied Physics Vol.26 No.-

The ablation processes of Cu film are investigated using temporal shaped femtosecond pulse trains. The depth is modulated by changing the number and interval of the sub-pulses. The underlying ultrafast dynamic processes are discussed based on plasma shielding and electron multiple heating mechanisms. When the sub-pulse interval is less than 0.4 ps electron multiple heating is the dominant mechanism, while the plasma shielding dominates the subsequent ablation processes when the sub-pulse interval is larger than 0.4 ps. The curve of depth obtained by three pulse trains shows more significant oscillation as the function of sub-pulse interval under the lowfluence. We propose that the oscillation of depth is due to the coherent phonon oscillation excited by the pulse train. The study provides a basis for giving insight into the ultrafast dynamics for improving micromachining and nano-fabrications using shaped femtosecond pulse trains.