Investigation on Pore-fracture of Coal and Its Influence Mechanism on Uniaxial Compression Failure Behavior

Yutao Li,Qingwei Guo,Yaodong Jiang,Bo Zhang,Xuehua Li 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

Pore-fracture is an important component of coal, affecting the uniaxial compression failure behavior. However, it is difficult to effectively characterize the influence mechanism because of the complexity and randomness of components in coal. In this paper, scanning electron microscope (SEM), computed tomography (CT), indentation hardness and uniaxial compressiontests are conducted for specimens with high, medium and no bursting proneness to investigate it. The results indicate that distribution of three components (matrix, minal and pore-fracture) in specimens are extremely different, which is the embodiment of tectonic structure activity and geological condition of mineralization. The levels of bursting proneness of coal, the tectonic structure features, tectonic structure activities and external functions are related. 3-D reconstruction on the basis of CT images can visualize internal complex structure of specimens. The numerical simulation results demonstrate that distribution of pore-fracture, mechanical properties of matrix and minal are significant inducement of specimen’s failure difference in the identical loading mode. Main failure mode of specimens with high, medium and no bursting proneness are different, which proves that main failure mode of specimen correlates with its mechanical properties. The mechanical failure behavior of specimen under uniaxial compression is influenced by loading mode, mechanical properties of matrix and minal, pore-fracture feature and other considerations. The loading mode is extrinsic cause of mechanical failure behavior of specimens, also an inducing factor and could be intervened. Furthermore, mechanical properties of matrix and minal determine bearing capacity and ultimate failure mode of specimens. Primary pore-fracture seriously affects extension process and extension mode of secondary pore-fracture, and the internal damage development of specimens. Notably, coal composed by the convergence of matrix, minal and pore-fracture, all these are internal cause of mechanical failure behavior of specimens, which belong to basic factors and hard to be intervened.

Robust Positive Consensus for Heterogeneous Multi-agent Systems

Ruonan Li,Yutao Tang,Shurong Li 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

This paper investigates a robust positive consensus problem for a class of heterogeneous high-order multi-agent systems subject to external inputs. Compared with existing multi-agent consensus results, the most distinct feature of the formulated problem is that the state variables of all heterogeneous agents are confined in the positive orthant. To solve this problem, we present a two-step design procedure. By constructing an auxiliary multi-agent system as positive local reference generators, we incorporate the reference generator into an applicable decentralized robust tracking controller for each agent. The proposed distributed algorithm is proven to ensure a robust consensus fulfilling certain prescribed pattern for the multi-agent system under switching topology in the sense of finite-gain stability with respect to the external inputs. A simulation example is finally given to illustrate the effectiveness of our design.

Measure for Reducing the Tensile Stress in Cement-Treated Soil Layerin Deep Excavation in Soft Clay

Li Wang,Yong Liu,Yutao Pan,William Danovan,Jeyatharan Kumarasamy,Fook-Hou Lee 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.9

Cement-stabilised soil layers (CSSLs) are often created to enhance lateral support to the retaining wall below the excavation level, such as those widely used in the construction of common service tunnels in Singapore. The CSSLs may be subjected to tensile stress or even cracks due to the underlying uplift pressure. Fully-coupled effective stress analyses were carried out using ABAQUS to explore the effectiveness of three measures for reducing the upheave-induced hogging of the CSSLs, i.e., increasing the thickness, usage of pressure-relief wells and usage of openings in the CSSLs. The results show that the usage of the opening is a more effective and more widely applicable measure compared to the other two measures.

Increase in Hypotonic Stress-Induced Endocytic Activity in Macrophages via ClC-3

Yutao Yan,Yu Ding,Bingxia Ming,Wenjiao Du,Xiaoling Kong,Li Tian,Fang Zheng,Min Fang,Zheng Tan,Feili Gong 한국분자세포생물학회 2014 Molecules and cells Vol.37 No.5

Extracellular hypotonic stress can affect cellular function. Whether and how hypotonicity affects immune cell function remains to be elucidated. Macrophages are immune cells that play key roles in adaptive and innate in immune reactions. The purpose of this study was to investigate the role and underlying mechanism of hypotonic stress in the function of bone marrow-derived macrophages (BMDMs). Hypotonic stress increased endocytic activity in BMDMs, but there was no significant change in the expression of CD80, CD86, and MHC class II molecules, nor in the secretion of TNF- or IL-10 by BMDMs. Furthermore, the enhanced endocytic activity of BMDMs triggered by hypotonic stress was significantly inhibited by chloride channel-3 (ClC-3) siRNA. Our findings suggest that hypotonic stress can induce endocytosis in BMDMs and that ClC-3 plays a central role in the endocytic process.

Yaw effects on train aerodynamics on a double-track viaduct: A wind tunnel study

Wenhui Li,Tanghong Liu,Pedro Martinez-Vazquez,Zhengwei Chen,Xiaoshuai Huo,Zijian Guo,Yutao Xia 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.3

The aerodynamic performance of a scaled high-speed train model mounted on a double-track viaduct was studied through a wind tunnel test. The pressure distribution of different loops and the centerline on the streamlined nose region, as well as the aerodynamic load coefficients of the leading car were explored under yaw effects ranging from β=-30° to β=30°. Results showed that Reynolds effects became independent when the wind speed surpassed 40 m/s, the corresponding Re of which equals 6.51 × 105 . The pressures recorded along the centerline of train nose for the upstream scenario, was more sensitive to the yaw effects as the largest pressure difference gradually broadened against yaw angles. In addition, the pressure coefficients along the centerline and symmetrical taps of the loops, approximately fit a quadratic relationship with respect to yaw angles. The presence of the tracks and viaduct decks somehow mitigated the intensity of the airflow at downstream side. The experimental test also revealed that, the upstream configuration provided higher mean side force, yawing, and rolling moments up to β=20° whereas over that angle the force and moments exhibited the opposite performance.

Aerodynamic analysis on the step types of a railway tunnel with non-uniform cross-section

Wenhui Li,Tanghong Liu,Xiaoshuai Huo,Zijian Guo,Yutao Xia 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.4

The pressure-mitigating effects of a high-speed train passing through a tunnel with a partially reduced cross-section are investigated via the numerical approach. A compressible, three-dimensional RNG k-ε turbulence model and a hybrid mesh strategy are adopted to reproduce that event, which is validated by the moving model test. Three step-like tunnel forms and two additional transitions at the tunnel junction are proposed and their aerodynamic performance is compared and scrutinized with a constant cross-sectional tunnel as the benchmark. The results show that the tunnel step is unrelated to the pressure mitigation effects since the case of a double-step tunnel has no advantage in comparison to a single-step tunnel, but the excavated volume is an essential matter. The pressure peaks are reduced at different levels along with the increase of the excavated earth volume and the peaks are either fitted with power or logarithmic function relationships. In addition, the Arc and Oblique-transitions have very limited gaps, and their pressure curves are identical to each other, whereas the Rec-transition leads to relatively lower pressure peaks in CP max, CP min, and ΔCP, with 5.2%, 4.0%, and 4.1% relieved compared with Oblique-transition. This study could provide guidance for the design of the novel railway tunnel.

Increase in Hypotonic Stress-Induced Endocytic Activity in Macrophages via ClC-3

Yan, Yutao,Ding, Yu,Ming, Bingxia,Du, Wenjiao,Kong, Xiaoling,Tian, Li,Zheng, Fang,Fang, Min,Tan, Zheng,Gong, Feili Korean Society for Molecular and Cellular Biology 2014 Molecules and cells Vol.37 No.5

Extracellular hypotonic stress can affect cellular function. Whether and how hypotonicity affects immune cell function remains to be elucidated. Macrophages are immune cells that play key roles in adaptive and innate in immune reactions. The purpose of this study was to investigate the role and underlying mechanism of hypotonic stress in the function of bone marrow-derived macrophages (BMDMs). Hypotonic stress increased endocytic activity in BMDMs, but there was no significant change in the expression of CD80, CD86, and MHC class II molecules, nor in the secretion of TNF-${\alpha}$ or IL-10 by BMDMs. Furthermore, the enhanced endocytic activity of BMDMs triggered by hypotonic stress was significantly inhibited by chloride channel-3 (ClC-3) siRNA. Our findings suggest that hypotonic stress can induce endocytosis in BMDMs and that ClC-3 plays a central role in the endocytic process.

Research on Intelligent Decision Based on Compound Traffic Field

Luo Yutao,Dai Jinkun,Li Hongluo 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4

Artificial potential fields (APF) and reinforcement learning (RL) are two common methods for the intelligent decision of autonomous vehicles. The process of vehicle driving includes the constraints of vehicle dynamics, traffic rules, road conditions, and other traffic vehicles, which are quite complex. The existing APF methods perform inadequately since they consider only limited factors and their effects. As such, it is difficult to adapt to increasingly complex traffic environments. In this paper, we propose a new concept, compound traffic field (CTF). The concept makes use of field theory to model various traffic environments based on the physical properties and traffic rules, besides, introduces the concept of the force correction field to reveal the interaction between the vehicle and the surrounding environment during driving. Moreover, an intelligent decision method and a co-simulation platform are established based on combining RL and CTF. The method has passed the tests in various scenarios built by PreScan and compared with the Conventional APF and modeless algorithm. For solving intelligent decision problems in the complex environment provides an applicable field model and its application method.

INTEGRATED COORDINATION CONTROL FOR DISTRIBUTED DRIVE ELECTRIC VEHICLE TRAJECTORY TRACKING

Hongluo Li,Yutao Luo 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.4

In order to fully explore the potential of distributed drive electric vehicle, an integrated coordination control method consists of model predictive control (MPC) and speed tracking control for trajectory tracking is proposed in this paper. Firstly, the vehicle dynamics model including the slip ratio of each wheel is established. Then, a multi-objective function of the MPC controller is established based on the principle of minimum tracking error, control vector, and control increment. And the optimal control sequences are obtained by optimizing the solution and correcting the feedback of the MPC, which satisfy both the actual kinematic constraints and the actuator performance constraints. The steering angle signal is sent to the steering motor directly, and the torque signal of each wheel which is obtained by superimposing the torque value output by the MPC controller and speed tracking controller is sent to the driving motor simultaneously. Finally, the proposed method is validated by using MATLAB/Simulink-Carsim co-simulation on different roads with conventional and severe pavement conditions. The simulation results show that the designed integrated coordination controller has obvious advantages in terms of tracking accuracy and body attitude stability during the course of lane change.

Band structure engineering of 2D materials using a 1D superlattice

Pilkyung Moon,Yutao Li,Carlos Forsythe,Takashi Taniguchi,Kenji Watanabe,Cory R. Dean 한국진공학회 2020 한국진공학회 학술발표회초록집 Vol.2020 No.8