Chunlei Ruan^1,2,*, Cengceng Dong¹, Zeyue Zhang¹, Boyu Chen¹, Zhijun Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.3, pp. 2707-2728, 2024, DOI:10.32604/cmes.2024.050003

Abstract Transient heat conduction problems widely exist in engineering. In previous work on the peridynamic differential operator (PDDO) method for solving such problems, both time and spatial derivatives were discretized using the PDDO method, resulting in increased complexity and programming difficulty. In this work, the forward difference formula, the backward difference formula, and the centered difference formula are used to discretize the time derivative, while the PDDO method is used to discretize the spatial derivative. Three new schemes for solving transient heat conduction equations have been developed, namely, the forward-in-time and PDDO in space (FT-PDDO) scheme,… More >

Mengdong An¹, Weiyuan Zhong¹, Wei Xu², Xiuli Wang^1,*

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1331-1349, 2024, DOI:10.32604/fdmp.2023.046604

Abstract The reactor coolant pump (RCP) rotor seizure accident is defined as a short-time seizure of the RCP rotor. This event typically leads to an abrupt flow decrease in the corresponding loop and an ensuing reactor and turbine trip. The significant reduction of core coolant flow while the reactor is being operated at full load can have very negative consequences. This potentially dangerous event is typically characterized by a complex transient behavior in terms of flow conditions and energy transformation, which need to be analyzed and understood. This study constructed transient flow and rotational speed mathematical More > Graphic Abstract

Ying Qu¹, Jinhao Wang¹, Xueting Cheng¹, Jie Hao¹, Weiru Wang¹, Zhewen Niu², Yuxiang Wu^2,*

Energy Engineering, Vol.121, No.7, pp. 1847-1863, 2024, DOI:10.32604/ee.2024.048300

Abstract The data-driven transient stability assessment (TSA) of power systems can predict online real-time prediction by learning the temporal features before and after faults. However, the accuracy of the assessment is limited by the quality of the data and has weak transferability. Based on this, this paper proposes a method for TSA of power systems based on an improved extreme gradient boosting (XGBoost) model. Firstly, the gradient detection method is employed to remove noise interference while maintaining the original time series trend. On this basis, a focal loss function is introduced to guide the training of… More >

Yuping Bian^*, Xiu Wan, Xiaoyu Zhou

Energy Engineering, Vol.121, No.6, pp. 1637-1656, 2024, DOI:10.32604/ee.2024.047678

Abstract To address uncertainty as well as transient stability constraints simultaneously in the preventive control of wind farm systems, a novel three-stage optimization strategy is established in this paper. In the first stage, the probabilistic multi-objective particle swarm optimization based on the point estimate method is employed to cope with the stochastic factors. The transient security region of the system is accurately ensured by the interior point method in the second stage. Finally, the verification of the final optimal objectives and satisfied constraints are enforced in the last stage. Furthermore, the proposed strategy is a general More >

Dawei Ruan¹, Mingwei Hu^1,2,3,4,5,*

CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.1, pp. 821-844, 2024, DOI:10.32604/cmes.2024.048392

Abstract The specialized equipment utilized in long-line tunnel engineering is evolving towards large-scale, multifunctional, and complex orientations. The vibration caused by the high-frequency units during regular operation is supported by the foundation of the units, and the magnitude of vibration and the operating frequency fluctuate in different engineering contexts, leading to variations in the dynamic response of the foundation. The high-frequency units yield significantly diverse outcomes under different startup conditions and times, resulting in failure to meet operational requirements, influencing the normal function of the tunnel, and causing harm to the foundation structure, personnel, and property… More >

Fei Wang, Qinpeng Meng, Jinchi Zhao, Xin Wang, Yuhong Liu, Qianru Zhang^*

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.4, pp. 829-846, 2024, DOI:10.32604/fdmp.2023.026917

Abstract Buildings with large open spaces in which chemicals are handled are often exposed to the risk of explosions. Computational fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large spaces. The turbulent Schmidt number (Sc_t) concept has typically been used in this regard, and most studies have adopted a default value. We studied the concentration distribution for sulfur hexafluoride (SF₆) assuming different emission rates and considering the effect of Sc_t. Then we examined the same problem for a light gas by assuming hydrogen gas (H₂) as the contaminant. When SF₆ was considered as More >

Shichao Cao^*, Yonggang Dong, Xiaoying Liu

Energy Engineering, Vol.121, No.4, pp. 1109-1125, 2024, DOI:10.32604/ee.2023.043004

Abstract The synchronous virtual machine uses inverter power to imitate the performance of the conventional synchronous machine. It also has the same inertia, damping, frequency, voltage regulation, and other external performance as the generator. It is the key technology to realize new energy grid connections’ stable and reliable operation. This project studies a dynamic simulation model of an extensive new energy power system based on the virtual synchronous motor. A new energy storage method is proposed. The mathematical energy storage model is established by combining the fixed rotor model of a synchronous virtual machine with the… More >

Chenlin Zhu¹, Yan Zhao¹, Zhitao Jiang¹, Jiafeng Xie³, Lifang Zeng^2,*, Lijuan Qian^1,*

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 107-127, 2024, DOI:10.32604/fhmt.2023.044433

Abstract Efficient and secure refueling within the vehicle refueling systems exhibits a close correlation with the issues concerning fuel backflow and gasoline evaporation. This paper investigates the transient flow behavior in fuel hose refilling and simplified tank fuel replenishment using the volume of fluid method. The numerical simulation is validated with the simplified hose refilling experiment and the evaporation simulation of Stefan tube. The effects of injection flow rate and injection directions have been discussed in the fuel hose refilling part. For both the experiment and simulation, the pressure at the end of the refueling pipe… More >

Muthasim Fahmy^†, Zhifa Sun

Frontiers in Heat and Mass Transfer, Vol.2, No.4, pp. 1-14, 2011, DOI:10.5098/hmt.v2.4.3003

Abstract A gas-liquid solute transfer process initiated in a closed vessel can exhibit Rayleigh-Bénard-Marangoni (RBM) convection enhanced mass transfer. For short exposure times experimental and theoretical results demonstrate that for deep liquid systems prior to solute penetration across the depth of the fluid, the stability thresholds of the system decreases with time. For thin liquid layers at longer exposure times the mass transfer enhancement under RBM convection can be affected in two ways: (1) solute penetration to the bottom liquid-solid boundary causing a departure from a penetration type concentration profile; (2) solute penetration to the top… More >

Arunn Narasimhan^*, Kaushal Kumar Jha

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-8, 2011, DOI:10.5098/hmt.v2.3.3005

Abstract Pan Retinal photocoagulation (PRP), a retinal laser surgical process, is simulated using a three-dimensional bio-heat transfer numerical model. Spots of two different type of array, square array of 3 × 3 spots and a circular array of six spots surrounding a central spot, are sequentially irradiated. Pennes bio-heat transfer model is used as the governing equation. Finite volume method is applied to find the temperature distribution due to laser irradiation inside the human eye. Each spot is heated for 100 ms and subsequently cooled for 100 ms with an initial laser power of 0.2 W. More >