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Identification of time-varying system and energy-based optimization of adaptive control in seismically excited structure

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 227-240页

作者： Elham Aghabarari Fereidoun Amini Pedram Ghaderi department of Civil Engineering Iran University of Science and TechnologyTehran 16844Iran

The combination of structural health monitoring and vibration control is of great importance to provide components of smart *** synthetic algorithms have been proposed,adaptive control that is compatible with changing conditions still needs to be used,and time-varying systems are required to be simultaneously estimated with the application of adaptive *** this research,the identification of structural time-varying dynamic characteristics and optimized simple adaptive control are ***,reduced variations of physical parameters are estimated online using the multiple forgetting factor recursive least squares(MFRLS)***,the energy from the structural vibration is simultaneously specified to optimize the control force with the identified parameters to be *** is also performed based on the probability density function of the energy under the seismic excitation at any ***,the optimal control force is obtained by the simple adaptive control(SAC)algorithm and energy coefficient.A numerical example and benchmark structure are employed to investigate the efficiency of the proposed *** simulation results revealed the effectiveness of the integrated online identification and optimal adaptive control in systems.

关键词： integrated online identification time-varying systems structural energy multiple forgetting factor recursive least squares optimal simple adaptive control algorithm

Facile synthesis of transition metal complexes with five coplanar metal-carbon σ-bonds

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National science Review 2024年第4期11卷 11-12页

作者： Guocheng Jia department of Chemistry Hong Kong University of Science and Technology

Carbon is one of the most important elements in chemistry, forming a vast number of organic compounds. It can also form a variety of organometallic compounds with a metal–carbon bond. Metal alkyl, carbene and carbyne complexes are classical examples of organometallic compounds. A particularly interesting class of organometallic compounds are all-carbon metallacycles formed by combination of a metal and a hydrocarbon chain serving as a chelating agent with only carbon atoms as the donor atoms. Many interesting monocyclic metallacycles made of a chelating bidentate hydrocarbon chain are known, for example, metallacyclobutadienes, metallacyclopentadienes and metallabenzenes[1].

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Nonlinear interaction of head-on solitary waves in integrable and nonintegrable systems

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Chinese Physics B 2024年第5期33卷 480-487页

作者：张树甜刘世鲲矫滕菲孙敏胡凤兰黄德财 department of Applied Physics Nanjing University of Science and TechnologyNanjing 210094China

This study numerically investigates the nonlinear interaction of head-on solitary waves in a granular chain(a nonintegrable system)and compares the simulation results with the theoretical results in fluid(an integrable system).Three stages(the pre-in-phase traveling stage,the central-collision stage,and the post-in-phase traveling stage)are identified to describe the nonlinear interaction processes in the granular *** nonlinear scattering effect occurs in the central-collision stage,which decreases the amplitude of the incident solitary *** with the leading-time phase in the incident and separation collision processes,the lagging-time phase in the separation collision process is *** asymmetrical nonlinear collision results in an occurrence of leading phase shifts of time and space in the post-in-phase traveling *** next find that the solitary wave amplitude does not influence the immediate space-phase shift in the granular *** space-phase shift of the post-in-phase traveling stage is only determined by the measurement position rather than the wave *** results are reversed in the *** increase in solitary wave amplitude leads to decreased attachment,detachment,and residence times for granular chains and *** the immediate time-phase shift,leading and lagging phenomena appear in the granular chain and the fluid,*** results offer new knowledge for designing mechanical metamaterials and energy-mitigating systems.

关键词： integrable system nonintegrable system granular chain solitary wave

Dissolution mechanism and kinetics ofβ(Mg_(17)Al_(12))phases in AZ91 magnesium alloy

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Journal of Magnesium and Alloys 2024年第4期12卷 1581-1592页

作者： Sultan Alomairy department of Physics College of ScienceTaif UniversityTaif 21944Saudi Arabia

In this study,the phase transformations,crystallization kinetics and dissolution mechanism ofβphase(Mg_(17)Al_(12))in magnesium alloy AZ91 were investigated by optical microscopy,X-ray diffraction,differential scanning calorimetry and differential *** results indicate that this AZ91 alloy undergoes a phase transformation during aging,a discontinuous precipitation of theβphase(Mg_(17)Al_(12))at 150℃at the grain boundaries and another continuous at 350℃within the *** activation energy of the dissolution reaction of theβphase(Mg_(17)Al_(12))under non-isothermal conditions is 116.781 kJ/mol,while it is 129.7383 kJ/mol under isothermal *** Avrami coefficient,n,relevant for the dissolution kinetics of theβphase(Mg_(17)Al_(12))is 1.152 and 1.211 in the non-isothermal and isothermal conditions *** numerical coefficients m and Avrami n are 0.993 and 1.152.

关键词： AZ91 kinetics β(Mg_(17)Al_(12)) Activation energy Discontinuous precipitation Continuous precipitation DSC

Omnidirectional color wavelength tuning of stretchable chiral liquid crystal elastomers

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Light(science & Applications) 2024年第6期13卷 1062-1074页

作者： Seungmin Nam Wontae Jung Jun Hyuk Shin Su Seok Choi department of Electrical Engineering Pohang University of Science and Technology(POSTECH)PohangKorea

Wavelength-tunable structural colors using stimuli-responsive materials,such as chiral liquid crystals(CLCs),have attracted increasing attention owing to their high functionality in various tunable photonic ***,on-demand omnidirectional wavelength control is highly desirable from the perspective of wavelength-tuning ***,despite numerous previous research efforts on tunable CLC structural colors,only mono-directional wavelength tuning toward shorter wavelengths has been employed in most studies to *** this study,we report the ideally desired omnidirectional wavelength control toward longer and shorter wavelengths with significantly improved tunability over a broadband wavelength *** using areal expanding and contractive strain control of dielectric elastomer actuators(DEAs)with chiral liquid crystal elastomers(CLCEs),simultaneous and omnidirectional structural color-tuning control was *** breakthrough in omnidirectional wavelength control enhances the achievable tuning freedom and versatility,making it applicable to a broad range of high-functional photonic applications.

关键词： tuning tunable directional

Rotating effects on the thermophysical properties of a two-dimensional GaAs quantum ring

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Communications in Theoretical Physics 2024年第6期76卷 165-173页

作者： Ahmad Ghanbari department of Physics College of ScienceYasouj UniversityYasoujIran

In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ***,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered *** to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered *** the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free *** results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum *** also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the *** results are discussed in detail.

关键词： Schrodinger equation quantum ring rotation effect thermophysical properties

How to achieve energy efficiency in buildings without compromising indoor air quality:A case study on enthalpy exchangers

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science China(Technological sciences) 2024年第9期67卷 2648-2658页

作者： LI Hao ZHANG Tao LIU XiaoHua department of Building science Tsinghua UniversityBeijing 100084China

As a representative heat recovery device,the fixed-plate enthalpy exchanger possesses the advantages of high recovery effectiveness,low pressure drop,and small space ***,indoor contaminants may transfer to fresh air through the enthalpy exchanger simultaneously,causing cross-contamination ***,the cross-contamination risk of the fixed-plate enthalpy exchanger has been under-researched in previous *** a result,this study experimentally investigates the energy performance,formaldehyde and ammonia transfer rates of paper-based and membrane-based enthalpy *** results illustrate that the enthalpy recovery effectiveness of the plate exchangers ranges from 60%–85%.The formaldehyde transfer rate through the exchangers varies from 5%–23%,and the ammonia transfer rate is 0–15%.The high effectiveness and low contaminant transfer rates are conducive to the promising application of the fixed-plate enthalpy *** addition,the energy reclaimed increases with the increase of the absolute indoor-outdoor enthalpy *** formaldehyde and ammonia transfer rates and cross-contamination risk slightly decrease with increasing temperature but significantly increase with increasing ***,the experimental results demonstrate that the contaminant transfer rates through the membranebased exchanger are lower than those of the paper-based *** study provides a reference for the fixed-plate enthalpy exchanger design in practical applications.

关键词： building energy efficiency enthalpy recovery heat recovery effectiveness cross-contamination

On optimal streaming kernelization algorithms

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science China(Information sciences) 2024年第8期67卷 337-338页

作者： Hao FENG Wei YANG Jianer CHEN School of Computer science Guangzhou University department of Computer science and Engineering Texas A&M University

The streaming model has been a popular model in big data computation. Streaming kernelization algorithms can be regarded as data compression processes on streaming data. In this study, we give a general method for developing computational lower bounds for streaming kernelization algorithms that is applicable to a large class of computational problems. As an example, we use the method to prove computational lower bounds for the well-known problem d-Hi TTin GSET.

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DIR:Dynamic Request Interleaving for Improving the Read Performance of Aged Solid-State Drives

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Journal of Computer science & Technology 2024年第1期39卷 82-98页

作者：聂世强张驰伍卫国 department of Computer science and Technology Xi'an Jiaotong UniversityShaanci 710049China

Triple-level cell(TLC)NAND flash is increasingly adopted to build solid-state drives(SSDs)for modern computer *** TLC NAND flash effectively improves storage density,it faces severe reliability issues;in partic-ular,the pages exhibit different raw bit error rates(RBERs).Integrating strong low-density parity-check(LDPC)code helps to improve reliability but suffers from prolonged and proportional read latency due to multiple read retries for worse *** straightforward idea is that dispersing page-size data across several pages in different types can achieve a low-er average RBER and reduce the read ***,directly implementing this simple idea into flash translation lay-er(FTL)induces the read amplification issue as one logic page residing in more than one physical page brings several read *** this paper,we propose the Dynamic Request Interleaving(DIR)technology for improving the performance of TLC NAND flash-based SSDs,in particular,the aged ones with large *** exploits the observation that the la-tency of an I/O request is determined,without considering the queuing time,by the access of the slowest device page,i.e.,the page that has the highest *** grouping consecutive logical pages that have high locality and interleaving their encoded data in different types of device pages that have different RBERs,DIR effectively reduces the number of read re-tries for LDPC with limited read *** meet the requirement of allocating hybrid page types for interleaved data,we also design a page-interleaving friendly page allocation scheme,which splits all the planes into multi-plane re-gions for storing the interleaved data and single-plane regions for storing the normal *** pages in the multi-plane re-gion can be read/written in parallel by the proposed multi-plane command and avoid the read amplification *** on the DIR scheme and the proposed page allocation scheme,we build DIR-enable FTL,which integrates the pro

关键词： triple-layer cell solid-state drive(TLC SSD) performance interleaving data unbalanced bit error rate