Table of Content

28 January 2025, Volume 59 Issue 1 Previous Issue   

New Type Power System and the Integrated Energy

Select

Summary of Research and Practice on V2G Technology of Transportation and Energy Fusion LIU Dongchen, JI Yu, HU Yue 2025, 59 (1):  1-15.  doi: 10.16183/j.cnki.jsjtu.2023.287 Abstract ( 346 )   HTML ( 18 )   PDF (13810KB) ( 103 )   Save Energy transformation in China is accelerating, with electrified transportation rapidly developing. However, the existing transportation system may struggle to meet the growing demand for renewable energy consumption, and the energy supply from the power grid could face challenges under increased load pressure. As a result, the integrated development of energy and transportation has become a pressing issue, with vehicle-to-grid (V2G) technology emerging as an area of research. This paper first examines the current status of V2G application both domestically and internationally. Then, it focuses on important V2G applications, reviewing the research and practical implementations of V2G in rail transit and new energy electric vehicles. It also introduces a novel V2G mode based on the personal rapid transit (PRT) system and compares the three V2G modes. Finally, it explores the potential of building an energy internet around V2G within the framework of “fusion of transportation and energy” and identifies future research directions. Figures and Tables | References | Related Articles | Metrics

Select

A Combined Clearing Model of Electric Energy, Inertia, and Primary Frequency Regulation Considering Emergency Interruptible Load Service ZHU Lan, ZHANG Xuehan, TANG Longjun, QIU Nianhang, TIAN Yingjie 2025, 59 (1):  16-27.  doi: 10.16183/j.cnki.jsjtu.2023.177 Abstract ( 237 )   HTML ( 12 )   PDF (2746KB) ( 330 )   Save The ever-increasing proportion of new energy units has led to prominent frequency safety issues in the power system. In order to avoid serious accidents after the system encounters large disturbance, it is necessary to purchase inertia and primary frequency regulation auxiliary services and integrate rapid response resources such as emergency interruptible load service into the system. Therefore, based on a review of the domestic and foreign inertia ancillary service market, the frequency safety constraints considering the emergency interruptible load service are derived, and a joint clearing model of electric energy, inertia, and primary frequency regulation auxiliary services is proposed, considering emergency interruptible load service. Then, the model is transformed into a mixed integer second-order cone programming model for optimization. Finally, the effectiveness of the model is verified based on a numerical example, and the influence of the frequency safety constraints on the system clearing results is discussed. Figures and Tables | References | Supplementary Material | Related Articles | Metrics

Select

Adaptive Frequency Regulation of Doubly-Fed Pumped Storage Unit Considering Speed and Power Limit LAO Wenjie, SHI Linjun, WU Feng, YANG Dongmei, LI Yang 2025, 59 (1):  28-37.  doi: 10.16183/j.cnki.jsjtu.2023.187 Abstract ( 153 )   HTML ( 7 )   PDF (1929KB) ( 78 )   Save Doubly-fed pumped storage unit can adjust its power flexibly through variable-speed operation, enabling it to participate in the frequency regulation of the grid in both generating and pumping modes. To explore the frequency regulation capability of doubly-fed pumped storage unit, frequency regulation modules adapted to the characteristics of units under different operating conditions are built, and a frequency regulation strategy with adaptive variable parameters considering the speed and power limit of the unit is proposed. First, based on the dynamic model of the unit considering reversible pump turbine, the frequency regulation modules are built, in which the frequency deviation is converted to additional power command in generating mode but to additional speed command in pumping mode. Then, the impacts of control parameters on the frequency dynamic response are analyzed, and the calculation method of optimal frequency regulation parameters under multi conditions is proposed based on the improved particle swarm optimization algorithm, which aims at minimizing the frequency deviation and takes the speed and power limit of the unit as constraints. Based on the proposed method, an adaptive frequency regulation strategy is further presented in which frequency regulation parameters adjust with the change of operating conditions of the unit. Finally, a four-machine two-zone system model with doubly-fed pumped storage unit is built, and the simulation results show that the frequency regulation strategy proposed can make the unit achieve a great frequency regulation performance under different operating conditions. Figures and Tables | References | Supplementary Material | Related Articles | Metrics

Naval Architecture, Ocean and Civil Engineering

Select

Centrifuge Tests on Vertical Bearing Capacity of Jacket Pile Foundation in Clay Seabed Under Different Grouting Effects SONG Junlin, LIU Bo, TANG Liheng, LIAO Chencong 2025, 59 (1):  38-47.  doi: 10.16183/j.cnki.jsjtu.2023.110 Abstract ( 133 )   HTML ( 7 )   PDF (15124KB) ( 159 )   Save Jacket foundations are often used as the main support structure for offshore wind turbines in waters with a depth of 40—60 meters. The jacket foundation is connected to the top of the pile foundation through underwater high-strength grouting to form a top sealing section, which together bears the vertical load. In this paper, centrifugal model tests are conducted for three different grouting effects: normal grouting at the top of a pile foundation, insufficient grouting, and poor grouting with through-holes. The vertical bearing capacity of the foundation and the bearing capacity sharing ratio between the grouting section and the pile body section under the limit state are analyzed, and compared with existing theoretical calculation methods. The results show that the bearing capacity of the grouting sealing cap depends on the sealing effect. For foundations with normal grouting and insufficient grouting of grouting sealing caps, the bearing capacity of grouting sealing caps accounts for approximately 25%—30% of the total bearing capacity of the foundation. When there are through-holes in poor grouting, the bearing capacity of the foundation grouting section develops early and quickly reaches its limit, whose sharing ratio is far lower than the other two bearing capacities. The test results in this paper can provide a reference for the calculation of bearing capacity in foundation design. Figures and Tables | References | Related Articles | Metrics

Select

Analysis Method for Ground Settlement Induced by Ultra-Deep Excavation in Hangzhou Soft Clay Considering Time-Space Effect XIONG Yifan, YING Hongwei, ZHANG Jinhong, CHENG Kang, LI Binghe 2025, 59 (1):  48-59.  doi: 10.16183/j.cnki.jsjtu.2023.199 Abstract ( 167 )   HTML ( 4 )   PDF (6054KB) ( 85 )   Save The PLAXIS 3D software and the soft soil creep model were used to establish a 3D numerical model of the B2 excavation within an ultra-deep excavation group, allowing for analysis of the effects of time-space factors on ground settlements. Then, the complementary error function and trilinear model were introduced. After that, the numerical results were used to correct the complementary error function. Finally, a rapid approach was proposed for predicting ground settlements while accounting for the temporal and spatial influences. The results indicate that soft soil creep not only causes additional wall deflections resulting in soil settlements but also induces soil settlements independent of these deflections. The impact of ignoring soft soil creep on prediction of ground settlement is not weaker than that of wall deflections. The excavation area determines the construction duration when the excavation depth and rate are identical, impacting ground settlements induced by soft soil creep. Figures and Tables | References | Related Articles | Metrics

Select

Force and Deformation Analysis of H(t)-T Loaded Pile Based on Pasternak Foundation Model JIANG Jie, CHEN Lijun, CHAI Wencheng, AI Yonglin, OU Xiaoduo, GONG Jian 2025, 59 (1):  60-69.  doi: 10.16183/j.cnki.jsjtu.2023.146 Abstract ( 180 )   HTML ( 5 )   PDF (2963KB) ( 154 )   Save The force and deformation of the pile foundation under the combined action of horizontal dynamic load H(t) and torque T are rather complicated. In order to more accurately analyze the internal force and displacement of the H(t)-T combined loaded piles, the shear effect of soil on the pile side is considered based on the Pasternak foundation model, and the H(t)-T coupling factor is introduced to reveal the influence mechanism of multi-directional load on pile response. Then, the virtual work principle is used to derive the comprehensive stiffness matrix of the pile element, and the modified finite beam element method is used to obtain the numerical solution of the internal force and displacement of the H(t)-T combined loaded piles. The results are compared with the results of the existing theoretical solutions and finite element simulation. The parametric analysis shows that soil shear effect can restrain the horizontal displacement of the pile, but has less effect on torsional deformation. The horizontal dynamic load enhances the torsional bearing capacity of the pile, and the torsional angle of the pile top is reduced by 22.6% when the horizontal dynamic load amplitude increases from 0.2Qu to 1.0Qu. Increasing the dimensionless frequency of the dynamic load will reduce the displacement of pile top and the maximum bending moment of pile body. The dynamic effect of simple harmonic load will be weakened with the increase of pile burial depth. The beam element model significantly reduces the number of discrete units and computation time, which can effectively improve the computational efficiency. Figures and Tables | References | Related Articles | Metrics

Select

Optimization Method of Underwater Flapping Foil Propulsion Performance Based on Gaussian Process Regression and Deep Reinforcement Learning YANG Yinghe, WEI Handi, FAN Dixia, LI Ang 2025, 59 (1):  70-78.  doi: 10.16183/j.cnki.jsjtu.2023.188 Abstract ( 167 )   HTML ( 9 )   PDF (6630KB) ( 35 )   Save In order to overcome the complexity and variability of underwater working environments, as well as the difficulty of controlling the flapping motion due to the significant nonlinear characteristics and numerous variables involved, a direct exploration approach is proposed to search for the optimal flapping foil propulsion parameters in the environment. The Latin hypercube sampling technique is utilized to obtain the samples of multi-dimensional flapping parameters in actual water pool data, and a Gaussian process regression (GPR) machine learning model is established based on these samples to generalize the working environment. Under different propulsion performance requirements, the TD3 algorithm in deep reinforcement learning (DRL) is trained for maximizing rewards and obtaining the optimal combination of multiple parameter actions in continuous intervals. The experimental results demonstrate that the GPR-TD3 method is capable of learning the globally optimal solution for flapping propulsion in the experimental environment, including maximum speed and maximum efficiency. Furthermore, the accuracy of this optimal solution can be intuitively verified through a two-dimensional contour plot in the GPR. Meanwhile, with 290 sets of real samples provided for any given propulsion speed requirement, the agent can recommend a set of action combinations with an error range of 0.23% to 6.68%, which can provide reference for practical applications. Figures and Tables | References | Related Articles | Metrics

Select

Ship Pipe Layout Based on Grid Normalized Astar Algorithm LIN Yan, ZHANG Qiaoyu, LOU Jiandi 2025, 59 (1):  79-88.  doi: 10.16183/j.cnki.jsjtu.2023.206 Abstract ( 226 )   HTML ( 8 )   PDF (12731KB) ( 134 )   Save In order to solve the existing problems of relying on manual experience to adjust the algorithm parameters, large difference of weight coefficient, and single result in ship pipe layout, a grid normalized Astar (GNAstar) is proposed. First, the mathematical models are established using bounding box and the grid method. Then, each path node is determined by the normalized weight values of different targets using the branch pipes splitting method, grid marking values, and the parent-child grid search strategy. The cost objective of traditional Astar only considering path length is extended to the comprehensive layout objective of pipes including length, bend consumption, and installation suitability. Finally, the GNAstar proposed is compared with the traditional Astar in a simulation case, and different pipe systems in ship engine room are taken as cases to further compare with the ant colony algorithm and particle swarm-Astar. The results show that the GNAstar proposed can obtain effective engineering solutions, and designers can obtain the corresponding layout result by setting the normalized weight coefficients of different targets. Figures and Tables | References | Related Articles | Metrics

Select

A Design Method of Inland River Channel Based on Hydrodynamic Response of Ship ZHANG Lei, FENG Shaoxiong, TAN Kun, GUO Tao, SONG Chengguo, CHU Xiumin, MIAO Yang 2025, 59 (1):  89-98.  doi: 10.16183/j.cnki.jsjtu.2023.175 Abstract ( 195 )   HTML ( 4 )   PDF (4707KB) ( 121 )   Save Channel is the navigable area for ships in rivers and canals. The analyses of flow details and experiences of engineers are extensively used for the design of channel nowadays, without thorough consideration of the fluid-structure interaction between flow and ships. In this paper, an inland channel design method based on ship hydrodynamic response is proposed. First of all, the secondary development is undertaken based on Fluent for the problem of ship-flow interaction, in which flow domain is simulated by using the finite volume method, and governing equations of ship are embedded through user defined function (UDF) and solved by using the fourth-order Runge-Kutta method. The dynamic mesh technique is adopted to update the changing computation domains. The hydrodynamic motion response of freely drifting ships in inland waterway is simulated, as well as trajectory. Then, the weighted least square method is used for curve fitting from the drifting trajectories of different ships, by which the channel boundaries are designed. The weight coefficients are obtained through the statistic of sailing frequencies of different ships. Dongliu route with typical navigation obstructions of curve and branch is chosen for the verification of the channel design method. It is found that the channel designed by the method with consideration of ship-flow interaction is consistent with the existing one. Besides, the analyses of flow details and ship responses indicate that ships sailing in this channel can avoid the influences of oblique flow and make use of the energy of flow, which maintains the sailing safety and economy. Figures and Tables | References | Related Articles | Metrics

Select

Pulsating Bubble Collapse and Jet Characteristics Near the Nozzle of Underwater Tube ZHANG Yueyao, QIAO Feng, LÜ Xiang, ZHANG Tianyuan, HAN Rui, LI Shuai 2025, 59 (1):  99-110.  doi: 10.16183/j.cnki.jsjtu.2023.118 Abstract ( 242 )   HTML ( 4 )   PDF (22230KB) ( 288 )   Save In this paper, the characteristics of a pulsating bubble collapse near the nozzle of an underwater tube were investigated both experimentally and numerically. The experiments involved generating pulsating bubbles using the electric spark discharge technology and capturing their transient behavior by high-speed photography. A boundary integral method based on potential flow theory was used to simulate the coupling between the bubble and the tube in the numerical simulation. The results show that the collapsing bubble can produce a jet directed towards the tube, which poses a safety threat to the pipeline equipment. The numerical simulation results and experimental phenomena are in good agreement. In addition, a systematic study was conducted of two dimensionless parameters, i.e., the ratio of bubble distance from the tube nozzle and the tube nozzle radius γ and the ratio of the maximum radius of the bubble and the tube nozzle radius λ. The findings indicate that when γ≤1.5, bubbles will only produce jets pointing into the tube during the collapse phase, and when γ>1.5, the tendency for bubbles to produce jets pointing into the tube increases as λ increases. Moreover, the maximum velocity of the downward jet increases with the increase of λ, and increases and then decreases with the increase of γ. Additionally, the maximum velocity of the downward jet generally increases with the increase of λ and increases and then decreases with the increase of γ. This study provides valuable insights into the dynamic behavior of bubble collapse near the nozzle of a submerged tube, which can provide safety measures for pipeline equipment. Figures and Tables | References | Related Articles | Metrics

Select

Assessment Method for Early Fatigue Failure of Crankshaft Based on Dispersion of Impact Energy LI Xiangzhe, LIANG Gang, ZHENG Xiaomei, XU Congcong, XU Jinquan 2025, 59 (1):  111-120.  doi: 10.16183/j.cnki.jsjtu.2023.203 Abstract ( 123 )   HTML ( 4 )   PDF (4630KB) ( 26 )   Save Considering scattering behaviors of strength and fatigue life characteristics of actual materials, a method for evaluating the early fatigue failure of crankshafts has been proposed. The micro-mechanism of the scatter of strength and life characteristics is the nonuniform distribution of microstructures (including micro-defects) inside the material, which can be uniformly characterized by the probability distribution of initial damage. For the same grade of alloy, the median values of strength and fatigue life can be basically the same, but the dispersion can be significantly different, which must be determined by sufficient sampling tests. For a diesel engine crankshaft forging made of the 34CrNi3MoA alloy, the dispersion of fatigue limit was estimated based on the scatter of impact sampling test data, while the mean value of probability distribution of fatigue limit was determined by structural fatigue tests. The safety factor recommended in the conventional design manual only implicitly assumes material dispersion. Considering the actual dispersion of the tested material, the quantitative relationship between safety factor and reliability has been established. Early fatigue failure of the crankshaft can easily occur when the actual dispersion of material fails to meet the specified reliability requirement. Figures and Tables | References | Related Articles | Metrics

Select

Effect of Wear-Resistant Tape Layers on Torsional Characteristics of Unbonded Flexible Pipes Under Internal Pressure LUO Chunmiao, FU Shixiao, ZHANG Mengmeng, CHEN Kunpeng, CUI Xiaoxuan 2025, 59 (1):  121-130.  doi: 10.16183/j.cnki.jsjtu.2023.163 Abstract ( 260 )   HTML ( 6 )   PDF (9450KB) ( 308 )   Save Unbonded flexible pipe has been widely used in the offshore oil and gas industry and its torsional balance plays an important role in safety insurance during the whole service life. However, there are still torsional imbalances due to simplifying assumptions in the current analytical theory. To improve the accuracy of torsion simulation and reduce the impacts on the practical applications of the pipelines, this paper focuses on the wear-resistant layer neglected in previous studies. Based on theoretical derivation, in combination with the finite element method, a correction algorithm for the torsional stiffness and elastic modulus of the tape layer is developed to investigate the effect of tape layer stacking on the overall torsion of the unbonded flexible pipe. The results show that overall torsion results obtained by using the corrected elastic modulus of the tape layer are closer to the test results, which have guiding significance for practical applications. Further sensitivity research shows that the width of the tape layer is positively correlated with the flexible pipe torsion angle, while the tape laying angle is negatively correlated with the overall torsion angle. With an increase in the stacking ratio of the tape, the pipeline torsion angle decreases. Figures and Tables | References | Related Articles | Metrics

Materials Science and Engineering

Select

Phase Transition, Magnetocaloric Effect, and Critical Behavior of Room Temperature Magnetic Refrigerant Material Mn5Ge2.7Zn0.3 XU Tongjie, LIU Zhenhua, JIN Huaiyu, LIU Jie, JIANG Xiuli, LI Zhe, LIU Yongsheng 2025, 59 (1):  131-138.  doi: 10.16183/j.cnki.jsjtu.2023.112 Abstract ( 195 )   HTML ( 7 )   PDF (4574KB) ( 352 )   Save Mn5Ge2.7Zn0.3 alloy was successfully prepared by using the arc-melting method, and its phase transition, magnetocaloric effect, and critical behavior were studied. The thermomagnetic curve determined that the Curie temperature of the sample was 297.2 K, the isothermal magnetization curve found that the sample had no thermal hysteresis. The sample underwent a second-order phase transition through the M2-H/M plot and Banerjee’s criterion, and the isothermal entropy change of the sample was further calculated according to Maxwell’s equation, and the power-law relationship of field-entropy and the normalization curve also verified the fact of the second-order phase transition. The critical index was solved by the modified Arrott plot(MAP) method, the Kouvel-Fisher(KF) method and the critical isothermal (CI) method, and the accuracy of the critical index was verified by Widom scaling ansatz and scaling laws. Finally, the Arrott-Noaks equation was used to further analyze the critical behavior of the sample, and the normalization slope and magnetic interaction distance were analyzed to confirm the complexity of the magnetic interaction inside the sample. Figures and Tables | References | Related Articles | Metrics

Select

Ballistic Penetration of Small-Caliber Bullet in Double-Arrow Honeycomb Core Structures with Negative Poisson’s Ratio LIU Yangzuo, XU Cheng, MA Wuning, REN Jie, ZHANG Zhendong 2025, 59 (1):  139-150.  doi: 10.16183/j.cnki.jsjtu.2023.293 Abstract ( 118 )   HTML ( 7 )   PDF (1784KB) ( 78 )   Save The anti-penetration performance of a double-arrow honeycomb sandwich structure with negative Poisson’s ratio (NPR) is investigated by using finite element simulation. With the penetration of small-caliber projectiles to nine types of arrowhead NPR honeycomb sandwich structures, the ballistic characteristics are obtained. The change in attitude during projectile penetration is obtained through simulation, and the dynamics simulation model of the projectile penetration double-arrow cell element is established. The simulation results show that when the thickness of the upper and lower layers are kept constant and only the double-arrow angle of the core layer is increased, the ballistic limit of the honeycomb sandwich structure is subsequently reduced. For the same honeycomb sandwich structure, there is a nonlinear relationship between the initial velocity of the bullet and the structural kinetic energy absorption rate. In addition, there is a specific velocity range within which the honeycomb sandwich structure exhibits optimal anti-penetration performance. During the penetration process, the projectile experiences an uneven distribution in the circumferential divection, which generates an asymmetric effect, altering the force environment, and leads to an unstable trajectory in the projectile’s penetration. Figures and Tables | References | Related Articles | Metrics