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Science China Technological Sciences 2024年第8期67卷 2436-2448页

作者： ZHU YanLong LI SuNing FAN JianHua KONG WeiQiang YUAN Yuan TAN HePing school of Energy Science and engineering Harbin Institute of Technology Department of civil engineering and mechanical engineering Technical University of Denmark school of Vehicle and Energy Yanshan University

In this study, a novel model of photothermal conversion in a direct absorption solar collector based on the Monte Carlo and finite volume methods was built and validated and the temperatures of the novel and traditional solar collectors were compared. The sensitivity of the parameters to the radiative heat loss was investigated. Finally, the radiative heat transfer characteristics were discussed using the radiative exchange factor. The results of this study validated the advantages of the novel solar collector at both the surface and fluid temperatures. Under the conditions used in this study, the maximum temperature difference of the novel solar collector was 30 K, compared with 193 K for the traditional solar collector. Furthermore, the collector was divided into several units along the flow direction. The radiative exchange factor indicated that with an increase in the attenuation coefficient, the percentage of radiation intensity in the total solar radiation absorbed by the corresponding unit ***, it decreased with an increase in the incident angle and scattering albedo. These results provide a reference for addressing the low efficiency and thermal damage caused by traditional solar collectors at high temperatures.

关键词： direct absorption solar collector radiative heat transfer Monte Carlo

Determining rock crack stress thresholds using ultrasonic through-transmission measurements

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International Journal of Coal Science & Technology 2024年第2期11卷 67-80页

作者： Jiangwan He Mehdi Serati Martin Veidt Arthur De Alwis school of civil engineering The University of QueenslandBrisbaneQLD 4072Australia school of mechanical and Mining engineering The University of QueenslandBrisbaneQLD 4072Australia

The crack initiation stress threshold is widely used in excavation industries as rock spalling strength when designing deep underground structures to avoid unwanted brittle *** various strain-based methods have been developed for the estimation of this critical design parameter,such methods are destructive and often requires subjective interpretations of the stress–strain curves,particularly in rocks with pre-existing microcracks or high *** study explore the applicability of non-destructive ultrasonic through-transmission methods for determining rock damage levels by assessing the changes in transmitted signal characteristics during *** change in velocity,amplitude,dominant frequency,and root-mean-square voltage are investigated with four different rock types including marble,sandstone,granite,and basalt under various stress *** suggest the rate of signal variations can be reliably used to estimate crack closure and crack initiation stress levels across the tested rocks before *** of the results between the conventional techniques and the new proposed methods based on ultrasonic monitoring are further discussed.

关键词： Ultrasonic Non-destructive testing Brittle rock Crack initiation Velocity Amplitude Frequency

In-depth analysis of VARTM-based solid-state supercapacitors utilizing CNT-dispersed cobalt-bismuth-samarium ternary hydroxide on woven carbon fiber for enhanced energy storage

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Journal of Energy Chemistry 2024年第10期97卷 498-512页

作者： Fouzia Mashkoor Mohd Shoeb Hongjun Jeong Mohammad Naved Khan Changyoon Jeong school of mechanical engineering Yeungnam University

Multi-metal hydroxides possess unique physical and chemical properties,making them promising candidates for supercapacitor working *** their electrochemical performance can be achieved through a combination with carbon *** this study,we synthesized a composite material by hydrothermally dispersed 4,6,and 10 wt% carbon nanotubes(CNT) into ternary cobaltbismuth-samarium hydroxide(CoBiSm-TOH).These nanocomposites were employed as the material for the working electrode in a *** findings reveal that at 1.5 A/g,the specific capacitance of CNT3@CoBiSm-TOH,using a three-electrode system,was found to be 852.91 F/g,higher than that of CoBi-BOH,CoBiSm-TOH,CNT1@CoBiSm-TOH and CNT5@CoBiSm-TOH-measuring 699.69,750.34,789.54 and 817.79 F/g,***,CNT3@CoBiSm-TOH electrodes exhibited a capacitance retention of around 88% over 10,000 *** demonstrate practical applicability,CNT3@CoBiSm-TOH was grown on woven carbon fiber(WCF),and a solid-state supercapacitor device was developed using the VARTM(vacuum-assisted resin transfer molding).This device displayed a specific capacitance of 272.67 F/g at 2.25 A/***,it achieved a maximum energy density of 53.01 Wh/kg at a power density of 750 W/kg and sustained excellent cycle stability over 50,000 cycles,maintaining 70% of its initial *** results underscore the importance of interfacial nanoengineering and provide crucial insights for the development of future energy storage devices.

关键词： Carbon nanotube Supercapacitor Synergistic effect Ternary hydroxide VARTM

Semi-analytical Solutions for Wellbores with Graded Skin Zones in Poroelastic Media

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Acta Mechanica Solida Sinica 2024年第3期37卷 385-395页

作者： Zhiqiang Fan Zhihe Jin school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China Department of mechanical engineering University of MaineOronoME04469USA

In analyzing the complex interaction between the wellbore and the reservoir formation,the hydromechanical properties of the region proximal to the wellbore,referred to as the“wellbore skin zone”,play a pivotal role in determining flow dynamics and the resulting formation *** models of the wellbore skin zone generally assume a constant permeability throughout,resulting in a sharp permeability discontinuity at the skin-reservoir *** paper introduces a model for a wellbore with a continuously graded skin zone of finite thickness within a poroelastic *** solutions are derived using the Laplace transform method,addressing both positive and negative skin *** results are presented to illustrate the effects of graded permeability/skin zone thickness on pore pressures and stresses around a *** results highlight a distinct divergence in stress and pore pressure fields when comparing wellbores with negative skin zones to those with positive skin zones or no skin at all.

关键词： Poroelastic Graded permeability Analytical solution Wellbore Skin zone

Reinforcement Learning-Based Energy Management for Hybrid Power Systems:State-of-the-Art Survey,Review,and Perspectives

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Chinese Journal of mechanical engineering 2024年第3期37卷 1-25页

作者： Xiaolin Tang Jiaxin Chen Yechen Qin Teng Liu Kai Yang Amir Khajepour Shen Li College of mechanical and Vehicle engineering Chongqing UniversityChongqing 400044China school of mechanical engineering Beijing Institute of TechnologyBeijing 100081China Department of mechanical and Mechatronics engineering University of WaterlooWaterlooON N2L 3G1Canada school of civil engineering Tsinghua UniversityBeijing 100084China

The new energy vehicle plays a crucial role in green transportation,and the energy management strategy of hybrid power systems is essential for ensuring energy-efficient *** paper presents a state-of-the-art survey and review of reinforcement learning-based energy management strategies for hybrid power ***,it envisions the outlook for autonomous intelligent hybrid electric vehicles,with reinforcement learning as the foundational *** of all,to provide a macro view of historical development,the brief history of deep learning,reinforcement learning,and deep reinforcement learning is presented in the form of a ***,the comprehensive survey and review are conducted by collecting papers from mainstream academic *** most of the contributions based on three main directions—algorithm innovation,powertrain innovation,and environment innovation—provides an objective review of the research ***,to advance the application of reinforcement learning in autonomous intelligent hybrid electric vehicles,future research plans positioned as“Alpha HEV”are envisioned,integrating Autopilot and energy-saving control.

关键词： New energy vehicle Hybrid power system Reinforcement learning Energy management strategy

Automatic Miscalibration Detection and Correction of LiDAR and Camera Using Motion Cues

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Chinese Journal of mechanical engineering 2024年第2期37卷 318-329页

作者： Pai Peng Dawei Pi Guodong Yin Yan Wang Liwei Xu Jiwei Feng school of mechanical engineering Southeast UniversityNanjing 211102China school of mechanical engineering Nanjing University of Science and TechnologyNanjing 210014China school of mechanical and Aerospace engineering Nanyang Technological UniversitySingaporeSingapore

This paper aims to develop an automatic miscalibration detection and correction framework to maintain accurate calibration of LiDAR and camera for autonomous vehicle after the sensor ***,a monitoring algorithm that can continuously detect the miscalibration in each frame is designed,leveraging the rotational motion each individual sensor ***,as sensor drift occurs,the projection constraints between visual feature points and LiDAR 3-D points are used to compute the scaled camera motion,which is further utilized to align the drifted LiDAR scan with the camera ***,the proposed method is sufficiently compared with two representative approaches in the online experiments with varying levels of random drift,then the method is further extended to the offline calibration experiment and is demonstrated by a comparison with two existing benchmark methods.

关键词： Autonomous vehicle LiDAR and camera Miscalibration detection and correction Sensor drift

Experimental,Numerical,and Analytical Studies on the Bending of mechanically Lined Pipe

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China Ocean engineering 2024年第2期38卷 221-232页

作者： WEI Wen-bin YUAN Lin ZHOU Jia-sheng LIU Zheng State Key Laboratory of Hydraulic engineering Simulation and Safety Tianjin UniversityTianjin 300072China school of civil engineering Tianjin UniversityTianjin 300072China school of mechanical engineering Tianjin UniversityTianjin 300072China

mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion *** installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole *** this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical *** types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,*** hydraulic expansion and bending experiments of small-scale MLPs are *** addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive *** contrast,the liner of ALP remains intact without developing any wrinkling and collapse *** addition,a dedicated numerical framework and theoretical models were also *** was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

关键词： lined pipe bending nonlinear ring theory buckling plasticity

Theoretical study on the effect of H_(2)O on the formation mechanism of NO_(x) precursors during indole pyrolysis

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Frontiers of Chemical Science and engineering 2024年第6期18卷 99-112页

作者： Ziqi Wang Jun Shen Xuesong Liu Sha Wang Shengxiang Deng Hai Zhang Yun Guo school of mechanical and Automotive engineering Shanghai University of Engineering ScienceShanghai 201620China school of mechanical engineering Shanghai Jiao Tong UniversityShanghai 200240China

The incineration technology of kitchen waste is one of the effective technologies to achieve the resource utilization of municipal solid *** is an important stage of *** is a rich initial product in the pyrolysis process of kitchen waste,and the presence of H_(2)O has a significant impact on the decomposition of indole to form NO_(x) ***,this study uses density functional theory method to study the effect of H_(2)O on the thermal decomposition of indole to produce NH_(3),HNCO,and *** H_(2)O participates in the reaction,it can provide oxidative groups to generate a new product HNCO,which is different from the previous findings by indole pyrolysis without the presence of H_(2)***,this study theoretically proves that NH_(3) is easier to form than *** is consistent with the phenomenon that NH_(3) release is higher than HCN release in pyrolysis *** addition,compared with the individual pyrolysis of indole,the participation of H_(2)O reduces the energy barriers for the formation of NH_(3) and HCN during indole pyrolysis,thereby promoting the formation of NH_(3) and HCN.

关键词： indole pyrolysis H_(2)O NO_(x)precursors DFT

Macro electrochemical milling and its hybrid variants

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Chinese Journal of Aeronautics 2024年第8期37卷 1-35页

作者： Ningsong QU Xiaolong FANG Junzhong ZHANG Huanghai KONG Yang LIU Minglu WANG Xiaokang YUE Yuehong MA Zhihao SHEN Jiajie CHEN College of mechanical and Electrical engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China school of mechanical engineering Jiangsu UniversityZhenjiang 212003China school of mechanical engineering Jiangsu University of Science and TechnologyZhenjiang 212003China school of mechanical engineering Hefei University of TechnologyHefei 230009China

Macro electromechanical milling has recently attracted increasing attention because numerous large thin-walled structures composed of difficult-to-cut materials are employed in the aerospace *** paper reviews recent developments in state-of-the-art macro electromechanical *** fundamental aspects of material removal mechanisms,such as the generation and breakdown behaviors of passive oxide films of typical difficult-to-cut materials,were *** methods for breaking down passive films are summarized,and simulation methods for the machining process coupling multiple physical fields are *** electrochemical milling methods,including fly mode electrochemical milling and sink electrochemical milling,are *** made to improve process performance,such as the material removal rate,surface quality,and machining accuracy,are *** addition,the main hybrid electrochemical milling methods,including electrochemical discharge milling,mechano-electrochemical milling,and electrochemical mill grinding,are also presented.

关键词： Electrochemical machining Electrochemical milling Material removal rate Surface quality Electrochemical discharge milling Electrochemical millgrinding

Theoretical Modeling and Surface Roughness Prediction of Microtextured Surfaces in Ultrasonic Vibration-Assisted Milling

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Chinese Journal of mechanical engineering 2024年第2期37卷 163-183页

作者： Chenbing Ni Junjie Zhu Youqiang Wang Dejian Liu Xuezhao Wang Lida Zhu school of mechanical and Automotive engineering Qingdao University of TechnologyQingdao 266525China school of mechanical engineering and Automation Northeastern UniversityShenyang 110819China

Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions,such as reducing friction,improving wear and increasing *** prediction of micro/nano surface textures is of great significance for the design,fabrication and application of functional textured *** this paper,based on the kinematic analysis of cutter teeth,the discretization of ultrasonic machining process,transformation method of coordinate systems and the cubic spline data interpolation,an integrated theoretical model was established to characterize the distribution and geometric features of micro textures on the surfaces machined by different types of ultrasonic vibration-assisted milling(UVAM).Based on the theoretical model,the effect of key process parameters(vibration directions,vibration dimensions,cutting parameters and vibration parameters)on tool trajectories and microtextured surface morphology in UVAM is ***,the effect of phase difference on the elliptical shape in 2D/3D ultrasonic elliptical vibration-assisted milling(UEVAM)was *** to conventional numerical models,the method of the cubic spline data interpolation is applied to the simulation of microtextured surface morphology in UVAM,which is more suitable for characterizing the morphological features of microtextured surfaces than traditional methods due to the presence of numerous micro *** prediction of surface roughness indicates that the magnitude of ultrasonic amplitude in z-direction should be strictly limited in 1D rotary UVAM,2D and 3D UEVAM due to the unfavorable effect of axial ultrasonic vibration on the surface *** study can provide theoretical guidance for the design and fabrication of microtextured surfaces in UVAM.

关键词： Theoretical modeling Microtextured surface Ultrasonic vibration-assisted milling Cubic spline interpolation Surface roughness