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Quantitative insight into fracture distribution during supercritical CO2 fracturing in tight sandstone formation

Petroleum Science 2025年第4期22卷 1670-1685页

作者： Yang, Bing Huang, Hai Ren, Qian-Qian Wang, Hai-Zhu Wang, Bin Ni, Jun Zheng, Yong Zhang, Wen-Tong The Key Laboratory of Well Stability and Fluid & Rock Mechanics in Oil and Gas Reservoir of Shaanxi Province Xi'an Shiyou University Shaanxi Xi'an710065 China College of Petroleum Engineering Xi'an Shiyou University Shaanxi Xi'an710065 China Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil & Gas Reservoirs Xi'an Shiyou University Shaanxi Xi'an710065 China State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum Beijing102249 China Co. Ltd Shaanxi Xi'an710065 China College of New Energy Xi'an Shiyou University Shaanxi Xi'an710065 China

Supercritical CO2 (SC-CO2) fracturing stands out a promising waterless stimulation technique in the development of unconventional resources. While numerous studies have delved into the induced-fracture mechanism of SC-CO2, the small scale of rock samples and synthetic materials used in many studies have limited a comprehensive understanding of fracture propagation in unconventional formations. In this study, cubic tight sandstone samples with dimensions of 300 mm were employed to conduct SC-CO2 fracturing experiments under true-triaxial stress conditions. The spatial morphology and quantitative attributes of fracture induced by water and SC-CO2 fracturing were compared, while the impact of in-situ stress on fracture propagation was also investigated. The results indicate that the SC-CO2 fracturing takes approximately ten times longer than water fracturing. Furthermore, under identical stress condition, the breakdown pressure (BP) for SC-CO2 fracturing is nearly 25% lower than that for water fracturing. A quantitative analysis of fracture morphology reveals that water fracturing typically produces relatively simple fracture pattern, with the primary fracture distribution predominantly controlled by bedding planes. In contrast, SC-CO2 fracturing results in a more complex fracture morphology. As the differential of horizontal principal stress increases, the BP for SC-CO2 fractured rock exhibits a downward trend, and the induced fracture morphology becomes more simplified. Moreover, the presence of abnormal in-situ stress leads to a further increase in the BP for SC-CO2 fracturing, simultaneously enhancing the development of a more conductive fracture network. These findings provide critical insights into the efficiency and behavior of SC-CO2 fracturing in comparison to traditional water-based fracturing, offering valuable implication for its potential applications in unconventional reservoirs. © 2025 The Authors

关键词： Sandstone

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Enhancing IC substrate manufacturing through differential geometry and lightweight networks for etching defect detection

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Journal of Manufacturing Systems 2025年 80卷 902-915页

作者： Yu, Yongxing Huang, Dan Hu, Yueming School of Automation Science and Engineering South China University of Technology Guangzhou510641 China Engineering Research Center of Precision Electronic Manufacturing Equipment Ministry of Education and Guangdong Provincial Engineering Laboratory for Advanced Chip Intelligent Packaging Equipment South China University of Technology Guangzhou510641 China Department of Automation North China Electric Power University Baoding071003 China Baoding key Laboratory of State Detection and Optimization Regulation for Integrated Energy System North China Electric Power University Baoding071003 China

With the advancement of high-density interconnect technology in semiconductor manufacturing, the precision and complexity of integrated circuit (IC) substrates have significantly increased, placing higher demands on quality control. Efficient and accurate detection of complex etching defects, which often occur during manufacturing, has become critical to preventing potential product defects. A defect detection method is proposed that combines a lightweight network with differential geometry tools to address the issue of etching defects in IC substrates. First, an improved deformable model is used to rapidly extract regular circuit trace contours from complex metallographic images, and morphological processing is applied to enhance the details, achieving precise image segmentation. For under-etching defects between circuit traces, differential processing of the original and segmented images is performed to locate abnormal regions. Subsequently, an optimized lightweight network based on MobileNet, termed OMNet, is designed to achieve the rapid identification of under-etching defects in these regions. For etching defects occurring on circuit traces, the DGEtch method employs a high-precision discrete curvature calculation based on the Frenet frame to evaluate angular discontinuities in contours, enabling accurate detection of etching defects. Experimental results demonstrate that the proposed method achieves an average recall rate of over 95% and maintains a precision above 90%. It exhibits high accuracy and stability in detecting etching defects and consistently outperforms existing models, particularly in handling complex mixed defects. This study provides an effective solution for detecting complicated defects in high-density IC substrate manufacturing. © 2025 The Society of Manufacturing Engineers

关键词： Inspection

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Aerodynamic Impact of Guide Vanes on a Two-Stage Counter-Rotating Lift Fan

Aerodynamic Impact of Guide Vanes on a Two-Stage Counter-Rot...

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15th Asia Conference on Mechanical and Aerospace engineering, ACMAE 2024

作者： Yang, Wenyu Shao, Weiping Deng, Jinlai Xu, Chenzhou School of Mechanical Engineering Shenyang Ligong University Shenyang China Liaoning Key Laboratory of Advanced Manufacturing Technology and Equipment Liaoning China Department of Precision Instrument Tsinghua University Beijing100084 China State Key Laboratory of Precision Space-time Information Sensing Technology Beijing100084 China

ISBN: (纸本)9781643685892

The lift fan is a critical component in vertical short takeoff and landing (VSTOL) fighters, enhancing thrust and offering significant applications in aerospace. To streamline airflow and optimize flow field distribution, guide vanes are often incorporated into lift fans to improve efficiency. However, studies on the aerodynamic impact of inlet and outlet guide vanes remain limited. This research examines the effects of inlet guide vane number and deflection angle, as well as the influence of outlet guide vanes on flow characteristics, using a two-stage counter-rotating lift fan as the subject. Findings indicate that fan lift increases steadily with the number of inlet guide vanes until reaching ten, after which additional vanes cause a rapid decrease in lift. The total pressure loss coefficient initially remains constant and then rises with increased inlet guide vane deflection angle. As adjustable vanes, the inlet guide vanes can pivot from approximately 80° to 20° to achieve gradual lift improvement. Compared to configurations without outlet guide vanes, the addition of outlet guide vanes significantly enhances airflow uniformity near the fan's exit, reducing aerodynamic losses and stabilizing the overall flow. © 2025 The Authors.

关键词： Flight simulators

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Synergistic effects of precursor reduction and ion migration blocking result in highly sensitive MAPbI₃ X-ray detectors with a low detection limit

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Journal of Materials Chemistry C 2025年第10期13卷 5317-5325页

作者： Jiang, Long Xue, Chengzhi Cheng, Jiatian Li, Nan Fan, Xinyu Yang, Yuanbo Li, Tiantian Li, Liwei Liu, Yucheng Feng, Jiangshan Liu, Shengzhong Yang, Zhou State Key Laboratory of Oil and Gas Equipment CNPC Tubular Goods Research Institute Shaanxi Xi’an 710077 China Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education Shaanxi Key Laboratory for Advanced Energy Devices Shaanxi Engineering Lab for Advanced Energy Technology School of Materials Science and Engineering Shaanxi Normal University Xi'an 710119 China Dalian Institute of Chemical Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Dalian 116023 China Dalian National Laboratory for Clean Energy iChEM Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian 116023 China

Lead halide perovskites have emerged as promising materials for sensitive, low-dose-rate X-ray imaging. However, the dark current drift caused by ion migration poses challenges to their long-term operational stability and performance. To address this issue, we explored the synergistic effects of precursor reduction and ion migration blocking. Reducing the precursor solution decreases the defect density, enhancing the carrier lifetime and mobility-lifetime product, thus boosting X-ray sensitivity. However, this approach alone does not effectively suppress dark current drift. By incorporating an ion migration blocker, the optimized device exhibits a significantly reduced dark current drift of 3.62 × 10⁻⁴ nA cm⁻¹ s⁻¹ V⁻¹, an improved X-ray sensitivity of 1.22 × 10⁵ μC Gy_air⁻¹ cm⁻² and a low detection limit of 3.93 nGy_air s⁻¹ under a 40 kV X-ray source and 12.66 V mm⁻¹ electrical field, positioning it among the best of polycrystalline perovskite X-ray detectors. Additionally, it can capture a clear X-ray image of a metal key at an X-ray dose of 2.85 μGy_air s⁻¹, highlighting its potential for low-dose X-ray imaging applications. © 2025 The Royal Society of Chemistry.

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Development of Ti–Mn alloys with low hysteresis and high capacity by introducing Cr

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International Journal of Hydrogen Energy 2025年 120卷 315-322页

作者： Zeng, Liang Luo, Liu He, Jian Zhu, Ding Mu, Shijia Wang, Wei Yan, Yigang Wu, Chaoling Chen, Yungui Institute of New Energy and Low-Carbon Technology Sichuan University Chengdu610041 China Engineering Research Center of Alternative Energy Materials & Devices Ministry of Education Sichuan University Chengdu610065 China State Key Laboratory of Environment-friendly Energy Materials Southwest University of Science and Technology Mianyang621010 China Department of Advanced Energy Materials College of Materials Science and Engineering Sichuan University Chengdu610065 China

Ti–Mn hydrogen storage alloys have excellent comprehensive advantages, including high reversible capacity, good cycling stability, and cost-effectiveness. However, the significant hydrogen absorption and desorption hysteresis hinders its practical applications. In this work, a systematic investigation is conducted into the effects of Cr content on the composition, structure, and hydrogen storage properties of Ti1.25Mn1.75-xCrx (x = 0, 0.05, 0.15, and 0.25) alloys, with a particular focus on the impact of Cr introduction on the hydrogen absorption and desorption hysteresis of these alloys. The experimental results indicate that the alloy exhibits the best overall hydrogen storage properties when x = 0.15, with a maximum reversible hydrogen storage capacity of 1.96 wt%. The introduction of Cr can significantly reduce hysteresis without notably altering the hydrogen absorption and desorption properties. The hysteresis factor decreases from 0.1881 (x = 0) to 0.0496 (x = 0.25). Notably, a reasonable explanation for how the introduction of Cr reduces hysteresis in Ti–Mn alloys based on the material's plastic deformation properties is given. This study provides insights for the design of Ti–Mn alloys with low hysteresis and high capacity. © 2025

关键词： Manganese alloys

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Main Protection Optimization Scheme for Generator Parallel Operation of Rotating Asynchronous Machine in Nuclear Power Plants

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IEEE Transactions on Power Delivery 2025年

作者： Wang, Yikai Xu, Chaozheng Qiao, Jian Dai, Zhihui Tan, Liming Yin, Xianggen State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources Baoding071003 China State Grid Hunan Electric Power Company Limited Research Institute Changsha410208 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology Wuhan430074 China

The Rotating Asynchronous Machine (RAM) system of a nuclear power plant provides a stable and reliable power supply for the control rod drive mechanism (CRDM) through two parallel generators. At present, the main protection of the generators in the RAM system is only configured with longitudinal differential protection, which cannot reflect the interturn short circuit fault and interbranch short circuit fault of the stator winding. Based on the characteristics of parallel connection of RAM generators in nuclear power plants, this article proposes a dual-generator split phase transverse differential protection and a dual-generator incomplete longitudinal differential protection. Through the internal fault set of the generator and the internal fault potential splitting model of the generator, the quantitative analysis of different main protection configuration schemes is carried out. It is concluded that the existing longitudinal differential protection and the incomplete longitudinal differential protection of two parallel generators can correctly reflect the vast majority of internal short-circuit faults. Finally, the dynamic experiment is carried out to prove the feasibility of the protection method in the actual unit operation. © 1986-2012 IEEE.

关键词： Nuclear power plants

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Enhanced subacute ischemic stroke treatment via multistage drug delivery system design for combination therapy

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Science China Chemistry 2025年

作者： Xihan Xu Juan-Juan Li Jiamin Li Hui-Yan Zhang Yilin Qi Bing-Sen Shi Tianqi Li Shan-Shan Su Weitao Zhao Chang Chen Zhongying Gong Huiyu Liu Ke-Rang Wang Dong-Sheng Guo Xue Xue State Key Laboratory of Medicinal Chemical Biology College of Pharmacy Nankai University College of Chemistry State Key Laboratory of Elemento-Organic Chemistry Key Laboratory of Functional Polymer Materials (Ministry of Education) Frontiers Science Center for New Organic Matter Collaborative Innovation Center of Chemical Science and EngineeringNankai University College of Chemistry and Materials Science State Key Laboratory of New Pharmaceutical Preparations and Excipients Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Ministry of Education) Key Laboratory of Chemical Biology of Hebei Province Hebei Research Center of the Basic Discipline of Synthetic Chemistry Hebei University Department of Neurology Tianjin First Central Hospital School of Medicine Nankai University Beijing Advanced Innovation Center for Soft Matter Science and Engineering State Key Laboratory of Organic-Inorganic Composites Beijing Laboratory of Biomedical Materials Bionanomaterials & Translational Engineering Laboratory Beijing Key Laboratory of BioprocessBeijing University of Chemical Technology

The management of acute ischemic stroke remains challenging due to its abrupt onset and the narrow treatment window,resulting in high rates of disability and *** therapy for neuroprotection and neurorepair strategies provided new hopes for subacute stroke *** we designed a multistage nanodelivery system that matches the unique microenvironment of the subacute phase of stroke,which utilizes calixarene as a building block to effectively load the neuroprotective drug *** calixarene is designed with glycosidic linkages targeting the glucose transporter 1 (GLUT1)on the blood-brain barrier (BBB) and azo bonds that are responsive to hypoxic ***,the decomposed calixarene molecules themselves possess intrinsic bio-activation to modulate inflammatory responses,achieving a multistage therapeutic approach that transitions from targeting to release and finally to *** approach combines anti-inflammation and neuroprotection,providing a multi-level treatment *** system was validated in a rat model of permanent middle cerebral artery occlusion (pMCAO),demonstrating that intravenous administration of the nanodelivery system repairs brain damage and improves motor function 24 h post-pMCAO *** work offers a precise and integrative strategy for stroke patients missing the acute therapy window to improve functional recovery and enhance the effect of comprehensive treatment.

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Theoretical Research on the Combustion Characteristics of Ammonium Dinitramide-Based Non-Toxic Aerospace Propellant

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Aerospace 2025年第4期12卷 295-295页

作者： Han, Jianhui Wen, Ming Hong, Yanji Du, Baosheng Jiang, Luyun Cui, Haichao Feng, Gaoping Song, Junling State Key Laboratory of Advanced Space Propulsion Department of Aerospace Science and Technology Space Engineering University Beijing101416 China

Propellants play a crucial role in the propulsion systems of aerospace vehicles, and their combustion characteristics are susceptible to external environmental conditions. This study systematically investigated the impact of various initial conditions on the combustion process of ADN-based propellant, including combustion products, equilibrium pressure, adiabatic temperature, and ignition delay time. The results indicate that the primary combustion products of ADN-based propellant include N2O, N2, CO2, OH, and others. ADN-based propellant exhibits a distinct two-stage combustion process under low pressure and temperature conditions (P0 = 2 atm, T0 = 586 K). Conversely, under high pressure and temperature conditions (P0 = 10 atm, T0 = 2930 K), the two stages of combustion occur almost simultaneously, making them difficult to distinguish. Furthermore, as the initial temperature increases, the ignition delay time decreases significantly, and the combustion rate accelerates. When the initial temperature rises from 400 K to 2800 K at a pressure of P0 =10 atm, the ignition delay time decreases from 3.5 ms to 0.6 μs. Interestingly, changes in initial pressure have a relatively minor impact on the ignition delay time compared to changes in temperature. Therefore, temperature has a more crucial influence on the combustion characteristics of ADN-based propellant than pressure. This study holds promise for providing new combustion optimization strategies for the aerospace industry and promoting the development of aircraft designs towards higher performance and sustainability. © 2025 by the authors.

关键词： Ignition

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Pulsating Torque Suppression of Flux Reversal Machines Based on Specific Harmonic Contributions of Rotor Permeance and PM MMF

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IEEE Transactions on Industry Applications 2025年

作者： Li, Junzhou Gao, Yuting Zhang, Chaofeng Zha, Xiaoming Qu, Ronghai Wuhan University School of Electrical Engineering and Automation Wuhan430072 China Key Laboratory of Integrated Energy Power Equipment and System Security Hubei430206 China State Grid Henan Electric Power Research Institute Zhengzhou450052 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

Flux reversal machines (FRMs) exhibit high torque density, but also significant pulsating torque, including cogging torque and torque ripple. Traditional methods fail to separate the harmonics that affect torque density and pulsating torque, leading to a degradation of torque density when reducing pulsating torque. Therefore, to maintain torque density and simultaneously reduce pulsating torque, this paper proposes a novel FRM configuration incorporating shape designs for the rotor and permanent magnets (PMs). First, the key generation mechanisms of cogging torque, average torque, and torque ripple are thoroughly examined, with analytical expressions derived to classify the torque contributions of all air-gap magnetic field harmonics into negative-effect and positive-effect components. Further, the rotor and PM shapes are designed to enhance the positive-effect components and reduce the negative-effect ones of the air-gap permeance and magnetomotive force (MMF). The impacts of geometric parameters are evaluated by using a sensitivity-based hierarchical optimization approach. Then, the proposed FRM is comprehensively compared with a conventional FRM in terms of back-electromotive force (EMF), cogging torque, average torque, torque ripple, efficiency, etc. The results indicate that the proposed machine configuration achieves reductions in cogging torque and torque ripple by 90% and 86.8%, respectively, while maintaining consistent average torque. Finally, a 12-slot/10-pole FRM prototype was built and tested to validate the effectiveness of the proposed machine topology. © 1972-2012 IEEE.

关键词： Permanent magnets

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High-Performance Flexible Magnetic Textile Fabricated Using Porous Juncus effusus Fiber for Biomechanical Energy Harvesting

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engineering 2025年第3期46卷 267-277页

作者： Junyao Gong Chunhua Zhang Liangjun Xia Zhaozixuan Zhou Weihao Long Zhuan Fu Sijie Zhou Hua Ji Lixin Du Weilin Xu State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200China College of Textile Science and Engineering Zhejiang University of Science and TechnologyHangzhou 310018China College of Textiles Donghua UniversityShanghai 201620China Winner Medical Co. Ltd.Wuhan 430200China Luthai Textile Co. Ltd.Zibo 255100China

Mechanical energy produced by human motion is ubiquitous,continuous,and usually not utilized,making it an attractive target for sustainable electricity-harvesting *** this study,flexible magnetic-Juncus effusus(M-JE)fibers were prepared from plant-extracted three-dimensional porous Juncus effusus(JE)fibers decorated with polyurethane and magnetic *** M-JE fibers were woven into fabrics and used for mechanical energy harvesting through electromagnetic *** M-JE fabric and induction coil,attached to the human wrist and waist,yielded continuous and stable voltage(2 V)and current(3 mA)during *** proposed M-JE fabric energy harvester exhibited good energy harvesting potential and was capable of quickly charging commercial capacitors to power small electronic *** proposed M-JE fabric exhibited good mechanical energy harvesting performance,paving the way for the use of natural plant fibers in energy-harvesting fabrics.

关键词： Juncus effusus Magnetic fabrics electromagnetic induction Energy harvest Mechanical-electrical energy conversion

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