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中国科学:技术科学（英文版）
中国科学:技术科学（英文版）

周光召

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中国科学:技术科学（英文版）/Journal Science China Technological SciencesCSCDCSTPCDEISCI
查看更多>>《中国科学》是中国科学院主办、中国科学杂志社出版的自然科学专业性学术刊物。《中国科学》任务是反映中国自然科学各学科中的最新科研成果，以促进国内外的学术交流。《中国科学》以论文形式报道中国基础研究和应用研究方面具有创造性的、高水平的和有重要意义的科研成果。在国际学术界，《中国科学》作为代表中国最高水平的学术刊物也受到高度重视。国际上最具有权威的检索刊物SCI，多年来一直收录《中国科学》的论文。1999年《中国科学》夺得国家期刊奖的第一名。
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    Experimental study and correlation development for the two-phase frictional pressure drop of flow boiling in copper foam fin microchannels

    FU KaiXU XiangHuaLIANG XinGang
    2758-2776页
    查看更多>>摘要：Flow boiling in microchannels with porous walls has received extensive attention in recent years.Compared with the emphasis on heat transfer,there is a lack of research on the effect of the porous wall structures on the pressure drop characteristics.In this study,systematic experiments are performed to measure the pressure drop of water-vapor two-phase flow in five microchannels with copper foam fins,which consist of nine or six channels and fins of copper foam.The porosities of the foam fins range from 0.78 to 0.82 and ratios of fin width to channel width range from 0.5 to 2.The channels are approximately 0.5 or 1 mm in width and 1 mm in height.Both adiabatic and flow boiling experiments are conducted with water at mass fluxes ranging from 66 to 407 kg/(m2 s).In the adiabatic experiments,the average quality in channels is between 0.017 and 0.846.In the flow boiling experiments,the outlet quality of channels is between 0.040 and 0.863.Slug flow,churn flow,annular flow,and wispy-annular flow are observed in adiabatic experiments.A two-phase frictional pressure drop correlation based on the Lockhart-Martinelli model is developed for copper foam fin microchannels by introducing the effects of the mass flux,porosity,ratio of fin width to channel width,and heating condition step by step.The mean absolute percentage errors of the new correlation are 7.53％for 325 data points under adiabatic conditions and 5.51％for 268 data points under flow boiling conditions,respectively.This work provides insight into the correlations of frictional pressure drop in microchannels with porous walls.
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    Multi-objective constructal design for quadrilateral heat generation body based on thermal-entransy theory and NSGA-Ⅱ

    CHEN LinGenZHU HongWeiGE YanLinSHI ShuangShuang...
    2777-2786页
    查看更多>>摘要：Based on thermal-entransy theory,the multi-objective constructal design of quadrilateral heat generation body(HGB)with similar shapes of leaves is studied further.The relationship between the aspect ratio of quadrilateral HGB and average tem-perature difference based on thermal-entransy dissipation is compared with that between the aspect ratio of quadrilateral HGB and the maximum temperature difference(MTD).The relationship between a composite function,consisting of linear weighting sum of the average temperature difference and MTD,and aspect ratio is obtained,and the optimal aspect ratios under minimum composite function with different weighting coefficients are obtained.Using the NSGA-Ⅱ algorithm,the Pareto frontier con-taining a series of compromise results of average temperature difference and MTD is obtained,and optimization results are compared using the deviation index.There is no aspect ratio to make both MTD and average temperature difference reach the minimum,and the optimal aspect ratio under the minimum MTD is smaller than that under the minimum average temperature difference.The optimal aspect ratio is obtained by making the composite function reach the minimum,and the optimal aspect ratios obtained by minimizing the composite function with different weighting coefficients are different.Compared with the construct of the initial design,the value of the composite function with optimal construct decreases by 1.9％,and the aspect ratio of the quadrilateral HGB decreases by 9.1％.The average temperature difference with the optimal construct increases by 2.1％,and the MTD with the optimal construct decreases by 5.6％.The deviation index under multi-objective optimization is smaller than that under single-objective optimization,and the obtained construct has better comprehensive thermal conductivity.Compared with TOPSIS and LINMAP decision-making methods,the average temperature difference with composite function optimization in-creases by 0.55％and 0.62％respectively,but the MTD with composite function optimization decreases by 0.84％and 0.96％.
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    Untrained neural network for linear tomographic absorption spectroscopy

    Chen JingRuoXu ShiJieLiu HeCongHuang JianQing...
    2787-2796页
    查看更多>>摘要：Linear tomographic absorption spectroscopy(LTAS)is a non-destructive diagnostic technique widely employed for gas sensing.The inverse problem of LTAS represents a classic example of an ill-posed problem.Linear iterative algorithms are commonly employed to address such problems,yielding generally poor reconstruction results due to the incapability to incorporate suitable prior conditions within the reconstruction process.Data-driven deep neural networks(DNN)have shown the potential to yield superior reconstruction results;however,they demand a substantial amount of measurement data that is challenging to acquire.To surmount this limitation,we proposed an untrained neural network(UNN)to tackle the inverse problem of LTAS.In con-junction with an early-stopping method based on running variance,UNN achieves improved reconstruction accuracy without supplementary training data.Numerical studies are conducted to explore the optimal network architecture of UNN and to assess the reliability of the early-stopping method.A comparison between UNN and superiorized ART(SUP-ART)substantiates the exceptional performance of UNN.
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    A novel distributed solar refrigeration system based on evacuated U-tube solar collector and elastocaloric refrigerator

    LI HaoZHANG HouCheng
    2797-2810页
    查看更多>>摘要：Refrigeration challenges in regions with electricity shortages significantly decrease the quality of life for residents.In response to the prevalent refrigeration challenges in power-deficient areas,a novel distributed solar refrigeration system,comprising an evacuated U-tube solar collector and elastocaloric refrigerator,is theoretically introduced.Theoretical formulations for the energy efficiency and cooling power of the solar refrigeration system are presented to facilitate predictive assessments of the performance properties.Under typical conditions,the energy efficiency and cooling power of the solar refrigeration system are,respectively,4.84％and 200.15 W.Subsequently,an extensive parameter study is conducted to comprehensively uncover key performance influencers and identify avenues for improvement.In addition,local sensitivity analyses identify that the length ratio is the top influential parameter,while the heat transfer fluid flow rate is the least sensitivity.A pragmatic case study,conducted with the weather data of Ningbo City,China,serves to empirically predict the performance of the hybrid system within the constraints of practical circumstances.
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    Reconfigurable paper-based metamaterial antenna:Structural transition from 2D to 3D

    PANG YaChenGAO SongYAO HuiMingWANG LiWei...
    2811-2816页
    查看更多>>摘要：Paper-based electronics offer a simple and cost-effective means to fabricate reconfigurable devices.In response to the problem of fixed shape and single function of most antennas,which limits their applications,a reconfigurable paper-based metamaterial antenna with 2D and 3D forms is presented for tunable operating frequency.The proposed antenna consists of two square split resonant rings fed by a coplanar waveguide.The working frequency of the 2D antenna is adjusted by the length,width,and opening size of the internal open resonant ring.While the folding angle of the antenna turns from 0° to 90°,the operating frequency of the paper-based metamaterial antenna changes from 2.759 to 4.223 GHz.In terms of 3D form,an additional resonant peak is generated by bending the paper-based metamaterial antenna,thus further realizing dual-band antenna design.After a simple process flow,a series of proposed antennas are fabricated and evaluated.The simulated and measured results both demonstrate that the proposed antenna has a good performance in turning the working band.The environment-friendly nature and pliability of paper,as well as simple fabrication procedures,make paper-based metamaterial promising candidates for future green electronics.
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    Instance segmentation from small dataset by a dual-layer semantics-based deep learning framework

    CHEN YiMingLI JianWeiHU XiaoBingLIU YiRui...
    2817-2833页
    查看更多>>摘要：Efficient and accurate segmentation of complex microstructures is a critical challenge in establishing process-structure-property(PSP)linkages of materials.Deep learning(DL)-based instance segmentation algorithms show potential in achieving this goal.However,to ensure prediction reliability,the current algorithms usually have complex structures and demand vast training data.To overcome the model complexity and its dependence on the amount of data,we developed an ingenious DL framework based on a simple method called dual-layer semantics.In the framework,a data standardization module was designed to remove extraneous microstructural noise and accentuate desired structural characteristics,while a post-processing module was employed to further improve segmentation accuracy.The framework was successfully applied in a small dataset of bimodal Ti-6Al-4V microstructures with only 112 samples.Compared with the ground truth,it realizes an 86.81％accuracy IoU for the globular αphase and a 94.70％average size distribution similarity for the colony structures.More importantly,only 36 s was taken to handle a 1024 x 1024 micrograph,which is much faster than the treatment of experienced experts(usually 900 s).The framework proved reliable,interpretable,and scalable,enabling its utilization in complex microstructures to deepen the understanding of PSP linkages.
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    Friction of graphene on a substrate with a cavity defect

    ZHOU PengHUO ZhanLeiCHANG TienChong
    2834-2841页
    查看更多>>摘要：The frictional behavior of supported graphene is known to be influenced by the physical properties and surface morphologies of the underlying substrate.However,it is unclear how a surface defect on the substrate affects the friction of supported graphene,and it is even unknown how to define the defect-induced friction force in this context.Here we conduct molecular dynamics(MD)simulations to investigate the friction between a square diamond slider and a graphene sheet supported by a copper substrate with a surface cavity defect.Our results demonstrate that the defect-induced friction exhibits a nonlinear increase with cavity size,while it decreases nonlinearly with slider size.We propose that the definition of defect-induced friction can be linked to the increase in friction work over the length of the slider,and is closely correlated to the defect-induced relative change in indentation depth and the ratio of the cavity area to the contact area.These findings provide a comprehensive evaluation of the impact of a substrate cavity defect on the friction of supported graphene and offer insights that may have broader implications for understanding defect-induced friction in other two-dimensional materials.
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    Predictor and ESO-based adaptive tracking control of heterogeneous vehicle platoon

    SUN ZhiZeLIU YangZHANG LinChuang
    2842-2852页
    查看更多>>摘要：This paper investigates the distributed adaptive platoon tracking problem of third-order heterogeneous vehicles subject to model uncertainties.The design process is divided into two steps.Firstly,an adaptive tracking controller is designed for the dynamic leading vehicle.And then,the distributed adaptive controllers are established for followers.Moreover,the predictor technique is used to improve the estimate performance of the adaptive law,and the total disturbance is approximated and compensated by the variable gain nonlinear extended state observers(NESOs)driven by the estimation error.By introducing the variable gain hyperbolic tangent tracking differentiator(HTTD),the"complexity explosion"problem is avoided.The feasibility and effectiveness of the proposed protocol are verified by simulation tests.
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    Simulation extractable SNARKs based on target linearly collision-resistant oracle

    WANG LiGuanLI YuanZHANG ShuangJunCAI DongLiang...
    2853-2866页
    查看更多>>摘要：The famous zero-knowledge succinct non-interactive arguments of knowledge(zk-SNARK)was proposed by Groth in 2016.Typically,the construction is based on quadratic arithmetic programs which are highly efficient concerning the proof length and the verification complexity.Since then,there has been much progress in designing zk-SNARKs,achieving stronger security,and simulated extractability,which is analogous to non-malleability and has broad applications.In this study,following Groth's pairing-based zk-SNARK,a simulation extractability zk-SNARK under the random oracle model is constructed.Our construction relies on a newly proposed property named target linearly collision-resistant,which is satisfied by random oracles under discrete logarithm assumptions.Compared to the original Groth 16 zk-SNARK,in our construction,both parties are allowed to use such a random oracle,aiming to get the same random number.The resulting proof consists of 3 group elements and only 1 pairing equation needs to be verified.Compared to other related works,our construction is shorter in proof length and simpler in verification while preserving simulation extractability.The results also extend to achieve subversion zero-knowledge SNARKs.
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    Event-triggered predefined-time control for full-state constrained nonlinear systems:A novel command filtering error compensation method

    PAN YingNanCHEN YiLinLIANG HongJing
    2867-2880页
    查看更多>>摘要：In this paper,a command filter-based adaptive fuzzy predefined-time event-triggered tracking control problem is investigated for uncertain nonlinear systems with time-varying full-state constraints.By designing a sliding mode differentiator,the inherent computational complexity problem within the predefined-time backstepping framework is solved.Different from the existing command filter-based finite-time and fixed-time control strategies that the convergence time of the filtering error is adjusted through the system initial value or numerous parameters,a novel command filtering error compensation method is presented,which tunes one control parameter to make the filtering error converge in the predefined time,thereby reducing the complexity of design and analysis of processing the filtering error.Then,an improved event-triggered mechanism(ETM)that builds upon the switching threshold strategy,in which an inverse cotangent function is designed to replace the residual term of the ETM,is proposed to gradually release the controller's dependence on the residual term with increasing time.Furthermore,a tan-type nonlinear mapping technique is applied to tackle the time-varying full-state constraints problem.By the predefined-time stability theory,all signals in the uncertain nonlinear systems exhibit predefined-time stability.Finally,the feasibility of the proposed algorithm is substantiated through two simulation results.
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