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Fluid Dynamics & Materials Processing 2025年第1期21卷 61-70页

作者： Chakar Khadija El Mouden Mahmoud Hajjaji Abdelowahed Laboratory of Engineering Sciences for energy(LabSIPE) University Research Center(CUR)in Renewable Energies&Intelligent Systems for Energy“EnR&SIE”National School of Applied SciencesChouaib Doukkali UniversityEl Jadida24000Morocco

The primary objective of this study is to develop an innovative theoretical model to accurately predict the thermophysicalproperties of hybrid nanofluids designed to enhance cooling in solar panel *** researchlays the groundwork for our future studies,which will focus on photovoltaic thermal *** nanofluidsconsist of water and nanoparticles of alumina(Al_(2)O_(3)),titanium dioxide(TiO_(2)),and copper(Cu),exploringvolumetric concentrations ranging from 0%to 4%for each type of nanoparticle,and up to 10%for total *** developed model accounts for complex interactions between the nanoparticles and the base fluid,as well assynergistic effects resulting from the coexistence of different *** simulations have shownexceptional agreement with experimental results,reinforcing the credibility of our approach in accurately capturingthe thermophysical behavior of these hybrid *** on these results,our study proposes significantadvancements in the design and optimization of nanofluids for cooling applications in solar *** developmentsare crucial for improving the efficiency of solar installations by mitigating overheating effects,providinga solid foundation for practical applications in this rapidly evolving field.

关键词： Nanoparticle thermophysical properties solar panel thermal conductivity specific heat

Effect of preprocessing on performances of machine learning-based mineral composition analysis on gas hydrate sediments, Ulleung Basin, East Sea

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Petroleum Science 2025年第1期22卷 151-162页

作者： Hongkeun Jin Ju Young Park Sun Young Park Byeong-Kook Son Baehyun Min Kyungbook Lee Department of Geoenvironmental Sciences Kongju National University Tunnel & Underground Facility Division ESCO Consultant & Engineers Company Yellow Sea Institute of Geoenvironmental Sciences Petroleum and Marine research Division Korea Institute of Geoscience and Mineral Resources Department of Climate and energy systems Engineering Ewha Womans University Center for Climate/Environment Change Prediction research Ewha Womans University

Gas hydrate(GH) is an unconventional resource estimated at 1000-120,000 trillion *** on GH is ongoing to determine its geological and flow characteristics for commercial production. After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin, the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD). Because the analysis is costly and dependent on experts, a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data. However, the model's performance was limited because of improper preprocessing of the intensity profile. Because preprocessing was applied to each feature, the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition. In this study, the profile was preprocessed for each sample using minmax scaling because relative intensity is critical for mineral analysis. For 49 test data among the 488data, the convolutional neural network(CNN) model improved the average absolute error and coefficient of determination by 41% and 46%, respectively, than those of CNN model with feature-based preprocessing. This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data. The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau. In addition, the overall procedure can be applied to any XRD data of sediments worldwide.

关键词： Sample-based preprocessing X-ray diffraction (XRD) Machine learning Mineral composition Gas hydrate (GH) Ulleung basin

Experimental study on energy Storage Characteristics of Sintered Ore Particle Packed Beds

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Journal of Thermal Science 2025年第1期34卷 242-253页

作者： LAI Zhenya DING Liwei LYU Hongkun HOU Chenglong CHEN Jiaying GUOXutao HAN Gaoyan ZHANG Kang State Grid Zhejiang Electric Power research Institute Hangzhou 310014China State Key Laboratory of Clean energy Utilization Zhejiang UniversityHangzhou 310027China

The particle packed bed energy storage system has advantages such as low costs and wide temperature ranges,which can be combined with solar thermal power generation systems to solve the inherent volatility and discontinuity of renewable *** new materials with low costs and excellent storage performances is one of the eternal research hotspots in the field of energy *** paper innovatively uses sintered ore particles as energy storage material and studies the effect of particle size on the airflow resistance characteristics,energy storage characteristics,and thermocline evolution characteristics of the packed bed through thermal energy storage *** results indicate that for the particles in the macro scale,the smaller the particle,the lower the absolute permeability of the bed and the greater the airflow *** packed bed with smaller particles has a larger specific surface area,larger bulk mass,and smaller bed ***,the packed beds with smaller particles have better thermocline characteristics,less irreversible loss,and can achieve higher thermal efficiency and higher exergy efficiency in the heat storage *** cycle thermal efficiency in packed beds with 25-40 mm,16-25 mm,and 10-16 mm particles is 53.58%,56.27%,and 57.60%,respectively,and the cycle exergy efficiency is 61.81%,69.25%,and 74.13%,***,this paper also studies the effect of discharging airflow rates on thermal storage *** experimental results indicate that suitable discharging strategies should be selected based on different heat demands.

关键词： particle packed bed airflow resistance thermal energy storage thermocline evolution

Accretion disk of a white hole

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Chinese Physics C 2025年第02期 259-269页

作者：李丽仿曹周键凌意吴小宁 Institute of Mechanics Chinese Academy of Sciences Academy of Mathematics and systems Science Chinese Academy of Sciences School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCAS Institute of High energy Physics Chinese Academy of Sciences School of Physics University of Chinese Academy of Sciences

A white hole is simply a region of spacetime described by general relativity. Black holes are often assumed to form through star collapses. Based on such an assumption, the white hole region does not present. Recent research on quantum gravity indicates that a black hole must convert into a white one to avoid the singularity difficulty encountered in general relativity. If such a theory is true, it is important to ask how white holes can be observed. Anything inside a white hole must be pushed outside. However, if a white hole is empty, nothing will escape from it. We can only observe the interaction behavior between the objects falling outside and the white hole. In this paper, we observe that the structure of the accretion disk around a white hole is exactly the same as the one around a black hole. The only possibility to distinguish a white hole from a black one is the light passing through the white hole. The image properties of white holes for such scenarios are investigated in this paper. Based on our analysis and current observation facts, we cannot certainly determine if M87 and Sgr A*are black or white holes.

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On the Stability Analysis of Switched Nonlinear systems with Time Varying Delay Under Arbitrary Switching

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Journal of systems Science & Complexity 2017年第2期30卷 329-346页

作者： KERMANI Marwen SAKLY Anis research unit of Industrial systems study and renewable energy(ESIER) National Engineering School of MonastirIbn El JazzarSkaness5019University of MonastirTunisia

This paper addresses the stability problem for a class of switched nonlinear time varying delay systems modeled by delay differential equations. By transforming the system representation under the arrow form and using a new constructed Lyapunov function,the aggregation techniques,the Borne-Gentina practical stability criterion associated with the properties, new delay-independent stability conditions of the considered systems are established. Compared with the existing results in this area, the obtained result is explicit, simple to use and allows us to avoid the problem of searching a common Lyapunov function. Finally, an example is provided, with numerical simulations,to demonstrate the effectiveness of the proposed method.

关键词： Arbitrary switching arrow form statepunov function continuous-time switched nonlinearstability.matrix Borne-Gentina criterion common Lya-time varying delay systems global asymptotic

Rivers increasingly warmer:Prediction of changes in the thermal regime of rivers in Poland

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Journal of Geographical Sciences 2025年第1期35卷 139-172页

作者： Mariusz PTAK Teerachai AMNUAYLOJAROEN Mariusz SOJKA Department of Hydrology and Water Management Adam Mickiewicz UniversityKrygowskiego 1061-680PoznańPoland School of energy and Environment University of PhayaoPhayao56000Thailand Atmospheric Pollution and Climate research unit School of Energy and EnvironmentUniversity of PhayaoPhayao56000Thailand Department of Land Improvement Environmental Development and Spatial ManagementPoznańUniversity of Life SciencesPiątkowska 94E60-649PoznańPoland

Emphasis on future environmental changes grows due to climate change,with simulations predicting rising river temperatures *** Poland,which has a long history of thermal studies of rivers,such an approach has not been implemented to *** study used 9 Global Climate Models and tested three machine-learning techniques to predict river temperature *** Forest performed best,with R^(2)=0.88 and lowest error(RMSE:2.25,MAE:1.72).The range of future water temperature changes by the end of the 21st century was based on the Shared Socioeconomic Pathway scenarios SSP2-4.5 and *** was determined that by the end of the 21st century,the average temperature will increase by 2.1°C(SSP2-4.5)and 3.7°C(SSP5-8.5).A more detailed analysis,divided by two major basins Vistula and Odra,covered about 90%of Poland's *** average temperature increase,according to scenarios SSP2-4.5 and SSP5-8.5 for the Odra basin rivers,is 1.6°C and 3.2°C and for the Vistula basin rivers 2.3°C and 3.8°C,*** Vistula basin's higher warming is due to less groundwater input and continental climate *** findings provide a crucial basis for water management to mitigate warming effects in Poland.

关键词： global warming forecasting water temperature Poland

Actuator fault diagnosis and severity identification of turbofan engines for steady-state and dynamic conditions

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Chinese Journal of Aeronautics 2025年第1期38卷 427-443页

作者： Yuzhi CHEN Weigang ZHANG Zhiwen ZHAO Elias TSOUTSANIS Areti MALKOGIANNI Yanhua MA Linfeng GOU School of Power and energy Northwestern Polytechnical UniversityXi’an 710129China Sichuan Gas Turbine research Establishment Aero Engine Corporation of ChinaChengdu 610500China Propulsion and Space research Center Technology Innovation InstituteAbu Dhabi 9639United Arab Emirates School of Integrated Circuits Dalian University of TechnologyDalian 116023China

Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed ***,fault diagnosis of gas turbine actuators has attracted considerable attention,from both academia and ***,the extensive literature that exists on this topic does not address identifying the severity of actuator faults and focuses mainly on actuator fault detection and *** addition,previous studies of actuator fault identification have not dealt with multiple concurrent faults in real time,especially when these are accompanied by sudden failures under dynamic *** study develops component-level models for fault identification in four typical actuators used in high-bypass ratio turbofan engines under both dynamic and steady-state conditions and these are then integrated with the engine performance model developed by the *** research results reported here present a novel method of quantifying actuator faults using dynamic effect *** maximum error for each actuator is less than0.06%and 0.07%,with average computational time of less than 0.0058 s and 0.0086 s for steady-state and transient cases,*** results confirm that the proposed method can accurately and efficiently identify concurrent actuator fault for an engine operating under either transient or steady-state conditions,even in the case of a sudden *** research results emonstrate the potential benefit to emergency response capabilities by introducing this method of monitoring the health of aero engines.

关键词： Turbofan engines Actuators Real time systems Fault identification Steady-state conditions Dynamic conditions

Bulk photovoltaic effect in two-dimensional ferroelectric α-In2Se3

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Science China(Information Sciences) 2025年第2期68卷 285-292页

作者： Huiting WANG Shuaiqin WU Yan CHEN Qianru ZHAO Jinhua ZENG Ruotong YIN Yuqing ZHENG Chang LIU Shukui ZHANG Tie LIN Hong SHEN Xiangjian MENG Jun GE Xudong WANG Junhao CHU Jianlu WANG State Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Shanghai Frontiers Science research Base of Intelligent Optoelectronics and Perception Institute of OptoelectronicsFudan University Hangzhou Institute for Advanced study University of Chinese Academy of Sciences Frontier Institute of Chip and System Fudan University

Non-centrosymmetric material systems can generate spontaneous photocurrent without a p-n junction under uniform illumination, which is known as the bulk photovoltaic effect（BPVE）. It has garnered significant attention for its application potential in the fields of energy harvesting and photoelectric detection. In this study, we report the BPVE observed in twodimensional ferroelectric α-In2Se3multilayer flakes. The reversal in spontaneous photocurrent polarity is observed and associated with the out-of-plane ferroelectric polarization direction. The spontaneous photocurrent originating from the shift current is also polarization-sensitive. The amplitude of spontaneous photocurrent is further increased by one order of magnitude through vacuum annealing. Our results provide a further application potential for new-generation photodetectors based on BPVE with low power consumption and multi-dimensional optoelectronic detection.

关键词： bulk photovoltaic effect 2D ferroelectrics 3R $\alpha$-In$_2$Se$_3$ shift current self-powered photodetection

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Contribution of the FPGAs for Complex Control Algorithms: Sensorless DTFC with an EKF of an Induction Motor

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International Journal of Automation and computing 2019年第2期16卷 226-237页

作者： Saber Krim Soufien Gdaim Abdellatif Mtibaa Mohamed Faouzi Mimouni Laboratory of Electronics and Microelectronics EE Faculty of SciencesUniversity of Monastir research unit "Industrial systems study and renewable energy" University of Monastir Polytechnic School of Engineering (PSE) University of Sousse National Engineering School University of Monastir

In a conventional direct torque control(CDTC) of the induction motor drive, the electromagnetic torque and the stator flux are characterized by high ripples. In order to reduce the undesired ripples, several methods are used in the literature. Nevertheless,these methods increase the algorithm complexity and dependency on the machine parameters such as the space vector modulation(SVM). The fuzzy logic control method is utilized in this work to decrease these ripples. Moreover, to eliminate the mechanical sensor the extended kalman filter(EKF) is used, in order to reduce the cost of the system and the rate of maintenance. Furthermore, in the domain of controlling the real-time induction motor drives, two principal digital devices are used such as the hardware(FPGA) and the digital signal processing(DSP). The latter is a software solution featured by a sequential processing that increases the execution time. However, the FPGA is featured by a high processing speed because of its parallel processing. Therefore, using the FPGA it is possible to implement complex algorithms with low execution time and to enhance the control bandwidth. The large bandwidth is the key issue to increase the system performances. This paper presents the interest of utilizing the FPGAs to implement complex control algorithms of electrical systems in real time. The suggested sensorless direct torque control using the fuzzy logic(DTFC) of an induction motor is successfully designed and implemented on an FPGA Virtex 5 using xilinx system generator. The simulation and implementation results show proposed approach s performances in terms of ripples, stator current harmonic waves, execution time, and short design time.

关键词： Direct torque control fuzzy logic control (FLC) extended Kalman filter Xilinx system generator (XSG) field programmable gate array (FPGA)

SDG space:Revealing the structure and complementarities among sustainable development goals in China

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Fundamental research 2025年第1期5卷 360-369页

作者： Mimi Gong Ke Yu Changchang Zhou Zhouyi Liu Zhenci Xu Ming Xu Shen Qu Center for systems Integration and Sustainability Department of Fisheries and WildlifeMichigan State UniversityEast LansingMI 48824USA Center for energy and Environmental Policy research Beijing Institute of TechnologyBeijing 100081China School of Geography Nanjing Normal UniversityNanjing 210023China Department of Geography The University of Hong KongHong Kong 999077China School of Environment Tsinghua UniversityBeijing 100084China

To achieve the united Nations Sustainable Development Goals(SDGs)by 2030,it is essential to understand the interlinkages between the *** research has investigated these interactions by focusing on their ***,few studies have systematically prioritized them from a structural perspective through the complementarity measurements and empirically validated their policy effectiveness,such as which goals and indicators impact other SDGs most,especially in *** study introduces a new concept known as the‘SDG space’by employing the“Product Space”approach in network science and *** measures the complementarities between SDGs and indicators through their network structures in investigating effective policy *** the most recent available but unpublished data for 31 Chinese provinces,the SDG space was constructed at the 17 SDG and 118 indicator levels by analyzing the probability of comparative advantage between each SDG or indicator pair co-occurring in the same *** data confirm that in the‘SDG Space’network,a goal connected to other well-developed goals would enjoy better future growth and vice *** structure reveals that SDG 4(Quality Education),15(Life on Land),and 1(No Poverty)are critical goals with transformative synergies to other ***,we identified strong complementarities between land-based ecosystems and clean water and climate actions using the finer-grained indicator-level *** findings help pave the way for China toward a sustainable future by providing science-based policy recommendations for *** can be generally applied to other countries and regions to assist in navigating toward sustainable development.

关键词： Sustainable development goals Network analysis SDG space Product space China