Macro-Micro Mechanical Behavior of Crushable Granular Materials under Generalized Stress Conditions

Yiming Liu,Chenming Xu,Guofang Xu,Haijun Mao,Zunqun Xiao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

This paper investigated the joint influence of particle crushing and intermediate principal stress coefficient on the macro and micro performances of granular assembles by using 3D discrete element method. The soil particle was modeled by crushable agglomerate. Numerical true triaxial tests with crushable agglomerates were performed. The mechanical behaviors of specimens with unbreakable agglomerates were also tested in this study. The results demonstrated that grain breakage can significantly affect the behaviors of granular soils in both macro and micro scales. Moreover, the present paper also showed that particle breakage did not influence the unique relationship between the intermediate principal stress coefficient band the deviatoric fabric of strong contacts. This can provide a good basis for developing micro-parameter-based constitutive model considering particle breakage for granular soils.

Self-Adaptive Power Flow Optimization Method for Multi-Terminal SNOP Considering the Difference of Risk of Node Voltage beyond Limit

Yiming Xu,Zhiqiang Wang,Zheng Fang,Sichao Xun,Guirong Hu,Yusheng Shen,Hongyi Xiao,Dongning Wu 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.5

Soft Normally Open Point (SNOP) is a power electronic device used widely in power distribution network. It can solve many problems by adjusting reactive power compensation and active power transmission. The uncertainty and fluctuation of distributed generation (DG) may cause many problems to the distribution network. In order to balance the safety and economy in power flow optimization better, a self-adaptive power flow optimization method for active distribution network with multi-terminal SNOP considering difference of the risk of node voltage beyond limit is put forward. It takes both weighted voltage deviation and the network loss into objective function to construct the optimal operation model and mainly has two improvements: one is considering initial voltage deviation and real-time penetration of the DG to establish the self-adaptive weight model of the sum of voltage deviation in the objective function; the other is putting forward the weighting strategy for node voltage deviation which decided by the electrical distance, DG position and correlation between source output and load. Then, taking three improved IEEE33 node feeders as an example to verify the validity of the strategy. The results validate that the self-adaptive strategy can reduce the loss and improve the regulation of voltage better and is useful in distribution network under different penetration

Performance of Homologous and Heterologous Prime-Boost Immunization Regimens of Recombinant Adenovirus and Modified Vaccinia Virus Ankara Expressing an Ag85B-TB10.4 Fusion Protein against Mycobacterium tuberculosis

( Yiming Kou ),( Mingming Wan ),( Wei Shi ),( Jie Liu ),( Zhilei Zhao ),( Yongqing Xu ),( Wei Wei ),( Bo Sun ),( Feng Gao ),( Linjun Cai ),( Chunlai Jiang ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.6

Tuberculosis (TB) remains a serious health issue around the word. Adenovirus (Ad)-based vaccine and modified vaccinia virus Ankara (MVA)-based vaccine have emerged as two of the most promising immunization candidates over the past few years. However, the performance of the homologous and heterologous prime-boost immunization regimens of these two viral vector-based vaccines remains unclear. In the present study, we constructed recombinant Ad and MVA expressing an Ag85B-TB10.4 fusion protein (AdH4 and MVAH4) and evaluated the impact of their different immunization regimens on the humoral and cellular immune responses. We found that the viral vector-based vaccines could generate significantly higher levels of antigen-specific antibodies, IFN-γ-producing splenocytes, CD69⁺CD8⁺ T cells, and IFN-γ secretion when compared with bacillus Calmette-Guerin (BCG) in a mouse model. AdH4-containing immunization regimens (AdH4-AdH4, AdH4-MVAH4, and MVAH4-AdH4) induced significantly stronger antibody responses, much more IFN-γ-producing splenocytes and CD69⁺CD8⁺ T cells, and higher levels of IFN-γ secretion when compared with the MVAH4-MVAH4 immunization regimen. The number of IFN-γ-producing splenocytes sensitive to CD8⁺ T-cell restricted peptides of Ag85B (9-1p and 9-2p) and Th1-related cytokines (IFN-γ and TNF-α) in the AdH4-MVAH4 heterologous prime-boost regimen immunization group was significantly higher than that in the other viral vector-based vaccine- and BCG-immunized groups, respectively. These results indicate that an immunization regimen involving AdH4 may have a higher capacity to induce humoral and cellular immune responses against TB in mice than that by regimens containing BCG or MVAH4 alone, and the AdH4-MVAH4 prime-boost regimen may generate an ideal protective effect.

Finite Time Fully Distributed Consensus Control for Multi-agent System With Input Saturation and Limited Communication Resources

Miao Xu,Yiming Fang,Jianxiong Li,Xiaodong Zhao 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.11

A finite-time fully distributed consensus (FTFDC) control problem is studied for a second-order multiagent system (MAS) with input saturation, limited communication resources and external bounded disturbances. Firstly, to deal with the input saturation characteristics, a second-order auxiliary system is designed to obtain the compensation signal. Secondly, because the leader information can only be obtained by a group of agents connected with the leader, a distributed estimator for each agent is designed to estimate the leader information. Then, to save communication resources, an event trigger condition is designed without continuous communication between agents. Based on the estimator and event trigger condition, a FTFDC controller is designed to realize the finite time fully distributed consensus control of MAS under limited communication resources and external bounded disturbances. Finally, the designed controller is verified by simulation on a multi-spacecraft attitude system model.

Application of Next Generation Sequencing in Laboratory Medicine

Zhong Yiming,Xu Feng,Wu Jinhua,Schubert Jeffrey,Li Marilyn M. 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.1

The rapid development of next-generation sequencing (NGS) technology, including advances in sequencing chemistry, sequencing technologies, bioinformatics, and data interpretation, has facilitated its wide clinical application in precision medicine. This review describes current sequencing technologies, including short- and long-read sequencing technologies, and highlights the clinical application of NGS in inherited diseases, oncology, and infectious diseases. We review NGS approaches and clinical diagnosis for constitutional disorders; summarize the application of U.S. Food and Drug Administration-approved NGS panels, cancer biomarkers, minimal residual disease, and liquid biopsy in clinical oncology; and consider epidemiological surveillance, identification of pathogens, and the importance of host microbiome in infectious diseases. Finally, we discuss the challenges and future perspectives of clinical NGS tests.

Review of Research Advances in Fruit and Vegetable Harvesting Robots

Xiao Xu,Wang Yaonan,Jiang Yiming 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

The idea of applying machine technology for fruit and vegetable harvesting has been around for 50 years. Various prototypes have been developed through the joint eforts of scholars worldwide. However, the existing prototypes of harvesting robots are still in the experimental research stage due to their low harvesting efciency. With the help of information technology, related research has reached a milestone, which is full of opportunities and challenges for harvesting robot researchers. This paper briefy introduces the composition and operation process of harvesting robots, so that readers have a clear understanding of harvesting robots and their harvesting principles. Then the research results of harvesting robots at home and abroad are systematically summarized, and the research progress of harvesting robots is analyzed in detail from three aspects: rapid and accurate identifcation and positioning of target fruits, end-efector of harvesting robots, and application of harvesting path planning in harvesting robots. The results show that improving harvesting efciency is the focus and hot spot of harvesting robot research. With the impetus of information technology, how to achieve fast and accurate recognition of multiple environments and multi-information outcomes, obtain reasonable path planning, and further optimize control strategies are all important research directions.

Simplified PWM Strategy for Neutral-Point-Clamped (NPC) Three-Level Converter

Zongbin Ye,Yiming Xu,Fei Li,Xianming Deng,Yuanzheng Zhang 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3

A novel simplified pulse width modulation(PWM) strategy for neutral point clamped (NPC) three-level converter is proposed in this paper.The direct output voltage modulation is applied to reduce the calculation time. Based on this strategy, several optimized control methods are proposed. The neutral point potential balancing algorithm is discussed and a fine neutral point potential balancing scheme is introduced. Moreover, the minimum pulse width compensation and switching losses reduction can be easily achieved using this modulation strategy. This strategy also gains good results even with the unequal DC link capacitor. The modulation principle is studied in detail and the validity of this simplified PWM strategy is experimentally verified in this paper. The experiment results indicated that the proposed PWM strategy has excellent performance, and the neutral point potential can be balanced well with unequal DC link captaincies.

Effects of Extrusion Temperature on the Properties of a 0.5 wt.% GNP/Al Composite in Porthole Die Extrusion

Shumei Lou,Yiming Li,Baojia Cheng,Lingwei Ran,Yue Wang,Leyao Xu,Ben Ma,Chungjian Su,Qingbiao Wang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.12

A 0.5 wt% GNP/Al composite was prepared by powder metallurgy and hot pressing. The numerical simulations and experimentsof porthole die extrusion were performed at 440 °C, 460 °C, 480 °C and 500 °C. The effect of extrusion temperatureon the microstructure and mechanical properties of the composites was studied. The results showed that the composite nearthe welding zone underwent dynamic recrystallization due to the large strain to form fine grains, some of which grew tocoarse grains because of the local high temperature. The extrusion temperature influenced the properties of the 0.5 wt%GNP/Al composite along both the extrusion and transverse directions. This influence is combined with synergistic effectson the recrystallization of the grain, fluidity and plasticity of the matrix, determined by the delamination, distribution andstructure of graphene and welding behavior in the welding zone. Therefore, the comprehensive mechanical properties ofthe composite reached the highest values in the extrusion direction and the transverse direction at 460 °C; the TEM imagesshowed that the graphene and aluminum matrix were in contact with each other via a small wavy transition overlapping zoneor that interaction forces caused by welding and shearing allowed the formation of a direct interface with the Al matrix. Thedeformed graphene formed a good interface with the matrix, ensuring outstanding mechanical properties in the welding zone.

Simplified PWM Strategy for Neutral-Point-Clamped (NPC) Three-Level Converter

Ye, Zongbin,Xu, Yiming,Li, Fei,Deng, Xianming,Zhang, Yuanzheng The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3

A novel simplified pulse width modulation(PWM) strategy for neutral point clamped (NPC) three-level converter is proposed in this paper.The direct output voltage modulation is applied to reduce the calculation time. Based on this strategy, several optimized control methods are proposed. The neutral point potential balancing algorithm is discussed and a fine neutral point potential balancing scheme is introduced. Moreover, the minimum pulse width compensation and switching losses reduction can be easily achieved using this modulation strategy. This strategy also gains good results even with the unequal DC link capacitor. The modulation principle is studied in detail and the validity of this simplified PWM strategy is experimentally verified in this paper. The experiment results indicated that the proposed PWM strategy has excellent performance, and the neutral point potential can be balanced well with unequal DC link captaincies.

Characteristics and prediction methods for tunnel deformations induced by excavations

Zheng, Gang,Du, Yiming,Cheng, Xuesong,Diao, Yu,Deng, Xu,Wang, Fanjun Techno-Press 2017 Geomechanics & engineering Vol.12 No.3

The unloading effect from excavations can cause the deformation of adjacent tunnels, which may seriously influence the operation and safety of those tunnels. However, systematic studies of the deformation characteristics of tunnels located along side excavations are limited, and simplified methods to predict the influence of excavations on tunnels are also rare. In this study, the simulation capability of a finite element method (FEM) considering the small-strain characteristics of soil was verified using a case study. Then, a large number of FEM simulations examining the influence of excavations on adjacent tunnels were conducted. Based on the simulation results, the deformation characteristics of tunnels at different positions and under four deformation modes of the retaining structure were analyzed. The results indicate that the deformation mode of the retaining structure has a significant influence on the deformation of certain tunnels. When the deformation magnitudes of the retaining structures are the same, the influence degree of the excavation on the tunnel increased in this order: from cantilever type to convex type to composite type to kick-in type. In practical projects, the deformation mode of the retaining structure should be optimized according to the tunnel position, and kick-in deformation should be avoided. Furthermore, two methods to predict the influence of excavations on adjacent tunnels are proposed. Design charts, in terms of normalized tunnel deformation contours, can be used to quantitatively estimate the tunnel deformation. The design table of the excavation influence zones can be applied to determine which influence zone the tunnel is located in.