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Comparison of optimizers for model predictive thermal control of buildings

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Energy and AI 2024年第1期15卷 279-287页

作者： Torben Andersen department of {1. Lund UniversityProfessorsgatan 1Lund22663Sweden

Considering recent developments in the energy sector,further reduction of electricity cost and flattening of the electric power demand curve are *** have focused on an autonomous electric heater control system that can easily be implemented in existing buildings without strict comfort *** are winter heating of warehouses and vacation homes,and heat drying of buildings under *** have set up a system that typically reduces electricity cost by about 40%on the basis of automatic weather and real time pricing *** system uses the building as an energy reservoir over periods with high electricity *** a model predictive control system,we compare use of a genetic algorithm,a particle swarm optimization,and a neural network for heater control,all working in a closed loop to reduce the influence of modeling *** have simulated the performance of the systems using realistic data and found that all three optimizers give about the same performance,varying only a few percent in ***,the computational and memory requirements of the neural network are much lower than for the other optimizers,so it is preferable for use with inexpensive *** carried out a full-scale experiment at a residential house and found agreement with simulation results.

关键词： Home energy management system Demand response Genetic algorithm Particle swarm optimization Neural network Model predictive control

Are hydrides under high-pressure-high-temperature superconductors?

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National Science Review 2024年第7期11卷 9-12页

作者： J.E.Hirsch department of {1. University of California

Contrary to the current consensus, I argue that the existing evidence for high-temperature superconductivity in hydrides under high pressure is not compelling. I suggest that the focus of the field should urgently shift to establish unequivocally experimentally whether or not superconductivity in pressurized hydrides exists, instead of continuing to search for new materials that might show elusive signals of unproven superconductivity at ever higher temperatures. The implications of a negative finding for the theoretical understanding of superconductivity are discussed.

关键词： Hydrides

Injection of a Self-propelled Polymer into a Small Circular Cavity

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Chinese Journal of Polymer Science 2024年第6期42卷 886-894页

作者： Chao Wang Yan-Li Zhou Xiao Yang Fan Wu Meng-Bo Luo department of {1. Taizhou UniversityTaizhou318000China department of {1. Zhejiang UniversityHangzhou310027China

The injection of a polymer chain into a small circular cavity under tangential self-propelled force is studied by using Langevin dynamics *** indicate that the injection dynamics of the active polymer shows strong correlation with the polymer conformation inside the cavity depending on the polymer rigidity(k_(b)).The injection timeτvaries nonmonotonously with increasing k_(b),and reaches its minimum at k_(b)^(*).When k_(b) is small(k_(b)≪k_(b)^(*)),the polymer is nearly random coil in the cavity,and spends a long time at the final stage of the injection process due to the large repulsion between monomers inside the *** k_(b) is moderate(k_(b)∼k_(b)^(*)),the part of polymer inside the cavity forms spiral configuration under the tangential active force,and the whole polymer moves synchronously with a constant velocity during the injection process,leading to a small injection *** k_(b) is large(k_(b)≫k_(b)^(*)),the polymer is nearly straight at the initial stage of the injection process,and takes a long time to bend itself,leading to a large injection time.

关键词： Active Polymer Injection Dynamics Simulation

Effects of Rattling Behavior of K and Cd Atoms along Different Directions in Anisotropic KCdAs on Lattice Thermal Transport and Thermoelectric Properties

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Energy & Environmental Materials 2024年第6期7卷 388-398页

作者： Yue Wang Yinchang Zhao Jun Ni Zhenhong Dai department of {1. Yantai UniversityYantai 264005China State Key Laboratory of Low-Dimensional Quantum physics Department of PhysicsTsinghua UniversityBeijing 100084China

We employ advanced first principles methodology,merging self-consistent phonon theory and the Boltzmann transport equation,to comprehensively explore the thermal transport and thermoelectric properties of ***,the study accounts for the impact of quartic anharmonicity on phonon group velocities in the pursuit of lattice thermal conductivity and investigates 3ph and 4ph scattering processes on phonon *** various methodologies,including examining atomic vibrational modes and analyzing 3ph and 4ph scattering processes,the article unveils microphysical mechanisms contributing to the lowκL within *** features include significant anisotropy in Cd atoms,pronounced anharmonicity in K atoms,and relative vibrations in non-equivalent As atomic *** atoms,situated between As layers,exhibit rattling modes and strong lattice anharmonicity,contributing to the observed lowκ*** flat bands near the valence band maximum translate into high PF,aligning with ultralowκL for exceptional thermoelectric *** optimal temperature and carrier concentration doping,outstanding ZT values are achieved:4.25(a(b)-axis,p-type,3×1.^(1.)cm^(−3),500 K),0.90(c-axis,p-type,5×1.^(20)cm^(−3),700 K),1.61.a(b)-axis,n-type,2×1.^(1.)cm^(−3),700 K),and 3.06(c-axis,n-type,9×1.^(1.)cm^(−3),700 K).

关键词： anharmonic lattice dynamics electron transport characteristics first principles calculation lattice thermal transport octahedron thermoelectric properties

Consistency between domain wall oscillation modes and spin wave modes in nanostrips

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Chinese physics B 2024年第6期33卷 511-516页

作者：董新伟吴振江 department of {1. and Institute of Theoretical {1. and Astro{1. Xiamen UniversityXiamen 361005China

Investigations on domain wall(DW) and spin wave(SW) modes in a series of nanostrips with different widths and thicknesses have been carried out using micromagnetic simulation. The simulation results show that the frequencies of SW modes and the corresponding DW modes are consistent with each other if they have the same node number along the width direction. This consistency is more pronounced in wide and thin nanostrips, favoring the DW motion driven by *** analysis of the moving behavior of a DW driven by SWs is also carried out. The average DW speed can reach a larger value of ~ 1.0 m/s under two different SW sources. We argue that this study is very meaningful for the potential application of DW motion driven by SWs.

关键词： micromagnetic simulation domain wall spin wave

Synthesis of nanostructured zinc oxide and its composite with carbon dots for DSSCs applications using flexible electrode

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Materials Reports(Energy) 2024年第3期4卷 77-83页

作者： Habtamu Fekadu Etefa Francis Birhanu Dejene department of {1. Walter Sisulu UniversityPrivate Bag X-1Mthatha5117South Africa

ZnO nanowires(ZnO NWs),ZnO nanoparticles(ZnO NPs)and carbon dots(C-dots)were synthesized by hydrothermal,sol-gel and hydrothermal methods *** were also characterized and applied for dye sensitized solar cells(DSSCs).The effects of C-dots on ZnO NWs and ZnO NPs have been *** C-dots were used at a mole ratio of citric acid(CA)to ethylene diamine(EDA)of 1.*** C-dots were found to enhance the performance of the flexible electrode *** the addition of C-dots,the power conversion efficiency(PCE)of ZnO NPs was boosted to be two times higher than that of ZnO NPs DSSCs without ***,the ultraviolet(UV)-band revealed a blue shift,resulting in a lower band gap and a reduced charge transfer resistance,which can enhance the PCE of *** loaded quantity on the flexible electrode substrate made of polyethylene terephthalate(PET)was optimized(50 mg).For DSSCs,the PET flexible electrode conductive polymer has produced positive *** ZnO NWs and ZnO NWs@C-dots,the PCE values were 1.45%and 4.25%;while for ZnO NPs and ZnO NPs@C-dots,they were 2.34%and 5.81.,*** work achieved remarkable and competitive performance when compared to solid(indium tin oxides/glass)-based substrate.

关键词： ZnO NWs@C-dots ZnO NPs@C-dots PET DSSCs Flexible electrode

Prospects and challenges in electrochemical nitrogen activation for ammonia synthesis

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Science China Chemistry 2024年第11期67卷 3510-3514页

作者： Xianbiao Fu Ib Chorkendorff department of {1. Technical University of Denmark

“The fixation of atmospheric nitrogen stands as one of the profound discoveries awaiting the ingenuity of chemists,”proclaimed William Crookes in his 1.98 speech [1.. This statement swiftly surged like a colossal wa... 详细信息

关键词： REDUCTION EFFICIENCY N-2

On the half-quantized Hall conductance of massive surface electrons in magnetic topological insulator films

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Science China(physics,Mechanics & Astronomy) 2024年第6期67卷 127-136页

作者： Rui Chen Shun-Qing Shen department of {1. The University of Hong KongHong Kong 999077China department of {1. Hubei UniversityWuhan 430062China

In topological insulators,massive surface states resulting from local symmetry breaking were thought to exhibit a half-quantized Hall conductance,obtained from the low-energy effective model in an infinite Brillouin *** a lattice model,the surface band is composed of a combination of surface states and bulk *** massive surface states alone may not be enough to support an exact one-half quantized surface Hall conductance in a finite Brillouin zone and the whole surface band always gives an integer quantized Hall conductance as enforced by the TKNN *** explore this,we investigate the band structures of a lattice model describing the magnetic topological insulator film that supports the axion insulator,Chern insulator,and semi-magnetic topological insulator *** reveal that the gapped and gapless surface bands in the three phases are characterized by an integer-quantized Hall conductance and a half-quantized Hall conductance,*** propose an effective model to describe the three phases and show that the low-energy dispersion of the surface bands inherits from the surface Dirac *** gapped surface band manifests a nearly half-quantized Hall conductance at low energy near the center of Brillouin zone,but is compensated by another nearly half-quantized Hall conductance at high energy near the boundary of Brillouin zone because a single band can only have an integer-quantized Hall *** gapless band hosts a zero Hall conductance at low energy but is compensated by another half-quantized Hall conductance at high energy,and thus the half-quantized Hall conductance can only originate from the gapless ***,we calculate the layer-resolved Hall conductance of the *** conclusion suggests that the individual gapped surface band alone does not support the half-quantized surface Hall effect in a lattice model.

关键词： magnetic topological insulator Dirac equation half-quantized Hall conductance

First-principles calculation on the electronic structures, phonon dynamics, and electrical conductivities of Pb_(1.)(PO_(4))_(6O) and Pb_(9)Cu(PO_(4))_(6O) compounds

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Journal of Materials Science & Technology 2024年第6期173卷 218-224页

作者： L.Y.Hao E.G.Fu State Key Laboratory of Nuclear physics and Technology Department of Technical PhysicsSchool of PhysicsPeking UniversityBeijing 100871China

Superconducting materials with high critical temperature have the potential to revolutionize many fields,including military,electronic communications,and power ***,scientists around the world have been tirelessly working with the ultimate goal of achieving high-temperature *** 2023,a preprint by Lee et *** South Korea claimed the discovery of ultra-high-temperature superconductivity with a critical temperature of up to 423 K in Cu-doped lead-apatite(LK-99)(arXiv:2307.1.008,arXiv:2307.1.037),which caused a worldwide sensation and ***,the electronic structures,phonon dynamics,and electrical conductivities of LK-99 and its parent compound lead-apatite have been calculated using first-principles *** results show that the lead-apatite compound and the LK-99 compound are insulator and half-metal *** flat band characteristic is consistent with previous *** electrical conductivity of the LK-99 compound shows two extreme points,and the electrical conductivity along the C-axis increases significantly after 400 *** phonon dispersion spectra of the compounds were investigated,demonstrating their dynamic instability.

关键词： Superconductivity LK-99 Lead-apatite First-principles calculation