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Applying the Shearlet-Based Complexity Measure for Analyzing Mass Transfer in Continuous-Flow Microchannels

Fluid Dynamics & Materials Processing 2024年第8期20卷 1743-1758页

作者： Elena Mosheva Ivan Krasnyakov institute of Continuous Media Mechanics UB RAS Perm614013Russia Department of applied Physics Perm National Research Polytechnic UniversityPerm614990Russia

Continuous-flow microchannels are widely employed for synthesizing various materials,including nanoparticles,polymers,and metal-organic frameworks(MOFs),to name a *** technology allows precise control over reaction parameters,resulting in purer,more uniform,and structurally stable products due to more effective mass transfer ***,continuous-flow synthesis processes may be accompanied by the emergence of spatial convective structures initiating convective *** the one hand,convection can accelerate reactions by intensifying mass *** the other hand,it may lead to non-uniformity in the final product or defects,especially in MOF microcrystal *** ability to distinguish regions of convective and diffusive mass transfer may be the key to performing higher-quality reactions and obtaining purer *** this study,we investigate,for the first time,the possibility of using the information complexity measure as a criterion for assessing the intensity of mass transfer in microchannels,considering both spatial and temporal non-uniformities of liquid’s distributions resulting from convection *** calculate the complexity using shearlet transform based on a local *** contrast to existing methods for calculating complexity,the shearlet transform based approach provides a more detailed representation of local *** analysis involves experimental images illustrating the mixing process of two non-reactive liquids in a Y-type continuous-flow microchannel under conditions of double-diffusive convection *** obtained complexity fields characterize the mixing process and structure formation,revealing variations in mass transfer intensity along the *** compare the results with cases of liquid mixing via a pure diffusive *** analysis,it was revealed that the complexity measure exhibits sensitivity to variations in the type of mass transfer,establishing its feasibility as an ind

关键词： Shearlet analysis complexity measure entropy measure convection microchannels double-diffusive instability

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Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

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Carbon Energy 2024年第4期6卷 164-221页

作者： Huilin Hou Gang Shao Yang Wang Wai‐Yeung Wong Weiyou Yang institute of Micro/Nano Materials and Devices Ningbo University of TechnologyNingboChina School of Materials Science and Engineering Zhengzhou UniversityZhengzhouChina Department of applied Biology and Chemical Technology and research institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongChina

Conversion of solar energy into H_(2) by photoelectrochemical(PEC)water splitting is recognized as an ideal way to address the growing energy crisis and environmental *** a typical PEC cell,the construction of photoanodes is crucial to guarantee the high efficiency and stability of PEC reactions,which fundamentally rely on rationally designed semiconductors(as the active materials)and substrates(as the current collectors).In this review work,we start with a brief introduction of the roles of substrates in the PEC ***,we provide a systematic overview of representative strategies for the controlled fabrication of photoanodes on rationally designed substrates,including conductive glass,metal,sapphire,silicon,silicon carbide,and flexible ***,some prospects concerning the challenges and research directions in this area are proposed.

关键词： hydrogen photoanode photoelectrochemical substrates water splitting

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Efficient micrometer-scale thick-film perovskite solar cells with superior stability

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Rare Metals 2024年第4期43卷 1647-1657页

作者： Jian-Fei Hu Gang Chen Shun-Zhang Yu Yue-Xin Lin Kai-Yu Wang Zong-Wei Li Guo-Dong Zhang Teng-Fei Pan Ya-Jing Li Ming-Jie Li Ying-Dong Xia Yi-Fan Lv Yong-Hua Chen Key Laboratory of Flexible Electronics(KLoFE)and institute of Advanced Materials(IAM) School of Flexible Electronics(Future Technologies)Nanjing Tech University(NanjingTech)Nanjing211816China Department of applied Physics The Hong Kong Polytechnic UniversityHong Kong999077China Shenzhen research institute The Hong Kong Polytechnic UniversityShenzhen518057China Optics Valley Laboratory Hubei430074China

It is essential to enhance the thickness of the absorber layer for perovskite solar cells(PSCs)to improve device performance and reduce industry ***,thick perovskite films(>1μm)are difficult to be fabricated by employing traditional solvents,such as N,N-dimethylformamide(DMF),dimethyl sulfoxide(DMSO).Besides,it is a challenge to fabricate thick-film perovskite owing to the deteriorated surface morphology and serious defect ***,a simple method was reported to deposit uniform pinhole-free perovskite films with a thickness of more than 2μm utilizing the methylamine acetate(MAAc)ionic liquid as the *** with methylammonium chloride(MACl)as an additive,thick-film perovskite with~2μm in grain size and few grain boundaries(GBs)was prepared,which dramatically improved the perovskite crystal quality and enhanced carrier transport *** final PSCs exhibited a power conversion efficiency(PCE)of 20.16%.The device showed improved stability with 95%of its initial efficiency in a nitrogen environment over 5000 *** work provides an alternative strategy to produce extremely efficient and stable thick-film *** can be believed that this device has great potential in the application of large areas and laminated PSCs.

关键词： Perovskite solar cells Thick-film Stability Ionic liquid

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Mitigating Lattice Distortion of High‑Voltage LiCoO_(2)via Core‑Shell Structure Induced by Cationic Heterogeneous Co‑Doping for Lithium‑Ion Batteries

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Nano-Micro Letters 2024年第3期16卷 169-182页

作者： Zezhou Lin Ke Fan Tiancheng Liu Zhihang Xu Gao Chen Honglei Zhang Hao Li Xuyun Guo Xi Zhang Ye Zhu Peiyu Hou Haitao Huang Department of applied Physics and research institute for Smart Energy The Hong Kong Polytechnic UniversityHong KongPeople’s Republic of China Department of applied Physics The Hong Kong Polytechnic UniversityHong KongPeople’s Republic of China institute of Nanosurface Science and Engineering Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics EngineeringShenzhen UniversityShenzhenPeople’s Republic of China School of Physics and Technology University of JinanJinanShandongPeople’s Republic of China

Inactive elemental doping is commonly used to improve the structural stability of high-voltage layered transition-metal oxide ***,the one-step co-doping strategy usually results in small grain size since the low diffusivity ions such as Ti^(4+)will be concentrated on grain boundaries,which hinders the grain *** order to synthesize large single-crystal layered oxide cathodes,considering the different diffusivities of different dopant ions,we propose a simple two-step multi-element co-doping strategy to fabricate core–shell structured LiCoO_(2)(CS-LCO).In the current work,the high-diffusivity Al^(3+)/Mg^(2+)ions occupy the core of single-crystal grain while the low diffusivity Ti^(4+)ions enrich the shell *** Ti^(4+)-enriched shell layer(~12 nm)with Co/Ti substitution and stronger Ti–O bond gives rise to less oxygen ligand ***-situ XRD demonstrates the constrained contraction of c-axis lattice parameter and mitigated structural *** a high upper cut-off voltage of 4.6 V,the single-crystal CS-LCO maintains a reversible capacity of 159.8 mAh g^(−1)with a good retention of~89%after 300 cycles,and reaches a high specific capacity of 163.8 mAh g^(−1)at *** proposed strategy can be extended to other pairs of low-(Zr^(4+),Ta^(5+),and W6+,etc.)and high-diffusivity cations(Zn^(2+),Ni^(2+),and Fe^(3+),etc.)for rational design of advanced layered oxide core–shell structured cathodes for lithium-ion batteries.

关键词： Lithium-ion battery LiCoO_(2) Heterogeneous co-doping Core-shell structure High-voltage stability

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Audio-Text Multimodal Speech Recognition via Dual-Tower Architecture for Mandarin Air Traffic Control Communications

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Computers, Materials & Continua 2024年第3期78卷 3215-3245页

作者： Shuting Ge Jin Ren Yihua Shi Yujun Zhang Shunzhi Yang Jinfeng Yang School of Computer Science and Software Engineering University of Science and Technology LiaoningAnshan114051China institute of applied Artificial Intelligence of the Guangdong-Hong Kong-Macao Greater Bay Area Shenzhen Polytechnic UniversityShenzhen518055China Shenzhen institutes of Advanced Technology Chinese Academy of SciencesShenzhen518055China Industrial training Centre Shenzhen Polytechnic UniversityShenzhen518055China

In air traffic control communications (ATCC), misunderstandings between pilots and controllers could result in fatal aviation accidents. Fortunately, advanced automatic speech recognition technology has emerged as a promising means of preventing miscommunications and enhancing aviation safety. However, most existing speech recognition methods merely incorporate external language models on the decoder side, leading to insufficient semantic alignment between speech and text modalities during the encoding phase. Furthermore, it is challenging to model acoustic context dependencies over long distances due to the longer speech sequences than text, especially for the extended ATCC data. To address these issues, we propose a speech-text multimodal dual-tower architecture for speech recognition. It employs cross-modal interactions to achieve close semantic alignment during the encoding stage and strengthen its capabilities in modeling auditory long-distance context dependencies. In addition, a two-stage training strategy is elaborately devised to derive semantics-aware acoustic representations effectively. The first stage focuses on pre-training the speech-text multimodal encoding module to enhance inter-modal semantic alignment and aural long-distance context dependencies. The second stage fine-tunes the entire network to bridge the input modality variation gap between the training and inference phases and boost generalization performance. Extensive experiments demonstrate the effectiveness of the proposed speech-text multimodal speech recognition method on the ATCC and AISHELL-1 datasets. It reduces the character error rate to 6.54% and 8.73%, respectively, and exhibits substantial performance gains of 28.76% and 23.82% compared with the best baseline model. The case studies indicate that the obtained semantics-aware acoustic representations aid in accurately recognizing terms with similar pronunciations but distinctive semantics. The research provides a novel modeling pa

关键词： Speech-text multimodal automatic speech recognition semantic alignment air traffic control communications dual-tower architecture

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Improved error estimates for a modified exponential Euler method for the semilinear stochastic heat equation with rough initial data

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Science China Mathematics 2024年

作者： Xinping Gui Buyang Li Jilu Wang Beijing Computational Science research Center Department of applied Mathematics The Hong Kong Polytechnic University School of Science Harbin Institute of Technology

A class of stochastic Besov spaces BpL2(Ω;H~α(O)), 1≤ p ≤∞ and α ∈ [-2, 2], is introduced to characterize the regularity of the noise in the semilinear stochastic heat equation du-△udt = f(u)dt + d W(t),under the following conditions for some α ∈(0, 1]:‖(∫t)0e~(-(t-s)A)dW(S)‖_(L2(Ω;L2(O)))≤Cta/2and ‖(∫t)0e~(-(t-s)A)dW(S)‖_(B~∞L2(Ω;H~α(O)))≤C The conditions above are shown to be satisfied by both trace-class noises(with α = 1) and one-dimensional space-time white noises(with α =1/2). The latter would fail to satisfy the conditions with α =1/2 if the stochastic Besov norm ∥·∥_(B~∞L2(Ω;H~α(O)))is replaced by the classical Sobolev norm ∥·∥_(L2(Ω;H~α(O))), and this often causes reduction of the convergence order in the numerical analysis of the semilinear stochastic heat equation. In this paper, the convergence of a modified exponential Euler method, with a spectral method for spatial discretization,is proved to have order α in both the time and space for possibly nonsmooth initial data in L4(Ω;H~β(O)) withβ >-1, by utilizing the real interpolation properties of the stochastic Besov spaces and a class of locally refined stepsizes to resolve the singularity of the solution at t = 0.

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Temporal and spatial differences in human activities performed in Urban Green Spaces of Vilnius(Lithuania)

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Geography and Sustainability 2024年第2期5卷 302-317页

作者： Luís Valença Pinto Carla Sofia Santos Ferreira Paulo Pereira research Centre for Natural Resources Environment and Society(CERNAS) Polytechnic Institute of CoimbraBencanta3045-601 CoimbraPortugal Environmental Management Laboratory Mykolas Romeris UniversityVilniusLithuania polytechnic institute of Coimbra Applied Research InstituteRua da MisericórdiaLagar dos Cortiços-S.Martinho do Bispo3045-093 CoimbraPortugal

Urban green spaces(UGS)are relevant to city well-being,as recognized by the United Nations’Sustainable Development Goals(SDGs).However,few studies have studied the temporal use of *** work assessed the seasonal,weekly,and daily use of three urban green spaces(Vingis Park,Bernardino Garden,and Jomantas Park)in Vilnius(Lithuania).The study is based on an on-site observation-based survey,which recorded users’characteristics,activities,and weather conditions during summer and *** results showed that UGS’s seasonal,weekly,and daily use differed according to park and users’*** with a higher diversity of facilities had a high seasonal difference in the number of observed *** numbers were higher in the summer for activities with children,social activities,sports,and water activities than in the *** Park had the lowest variability in user *** variables were linked to changes in users’*** precipitation and lower temperature were associated with reducing the number of users and the diversity of registered *** of the stationary activities were observed during *** diversity of the observed activities was associated with the available facilities rather than the park *** distribution of stationary activities was spatially correlated with facility/equipment(benches,playgrounds,sports,and fitness equipment)and proximity to water *** results of this study are relevant for UGS design,planning,and management.

关键词： Urban parks Seasonal differences Temporal use Time of day Spatial distribution of UGS users

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Controllable synthesis of one-dimensional silicon nanostructures based on the dual effects of electro-deoxidation and the Kirkendall effect

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Nano research 2024年第9期17卷 7814-7823页

作者： Jianxin Tu Shuo Yu Kui Hao Le Sun Ruicheng Bai Fangzhou Zhang Aijun Li Hong Liu institute of Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China Department of applied Physics The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shaoxing institute of technology Shanghai UniversityShanghai 200444China

In this study,we successfully synthesized silicon nanotubes(Si-NTs)and silicon nanowires(Si-NWs)in a controllable manner using a catalyst-and template-free method through the direct electrolysis of SiO_(2)in a molten CaCl_(2)-CaO system,while also proposing a novel formation mechanism for ***-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO_(2)decomposition *** subsequently adjusting the voltage to a value between the decomposition potentials of CaCl_(2)and CaO,in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs,leading to the formation of a Ca *** formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs,as the outward diffusion rate of Si exceeds the inward diffusion rate of *** differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall *** vacancies gradually accumulate and merge,forming large voids,which ultimately result in the formation of hollow *** a subsequent dealloying process,the removal of the embedded calcium leads to the formation of *** the application of a carbon coating,the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g^(-1)at 1.5 A·g^(-1)and exhibits exceptional long-term cycling stability,maintaining a capacity of 977 mAh·g^(-1)after 2000 cycles at 3.0 A·g^(-1).

关键词： silicon nanotubes silicon nanowires lithium-ion battery Kirkendall effect

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Polyethylene interfacial dielectric layer for organic semiconductor single crystal based field-effect transistors

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Chinese Chemical Letters 2024年第4期35卷 431-435页

作者： Min Chen Boyu Peng Xuyun Guo Ye Zhu Hanying Li Department of Polymer Science and Engineering MOE Key Laboratory of Macromolecular Synthesis and FunctionalizationInternational Research Center for X PolymersShanxi-Zheda Institute of Advanced Materials and Chemical EngineeringZhejiang UniversityHangzhou 310027China Department of applied Physics Research Institute for Smart EnergyThe Hong Kong Polytechnic UniversityHong Kong 999077China

Organic semiconductor single crystals(OSSCs) have shown their promising potential in high-performance organic field-effect transistors(OFETs). The interfacial dielectric layers are critical in these OFETs as they not only govern the key semiconductor/dielectric interface quality but also determine the growth of OSSCs by their wetting properties. However, reported interfacial dielectric layers either need rigorous preparation processes, rely on certain surface chemistry reactions, or exhibit poor solvent resistance, which limits their applications in low-cost, large-area, monolithic fabrication of OSSC-based OFETs. In this work, polyethylene(PE) thin films and lamellar single crystals are utilized as the interfacial dielectric layers, providing solvent resistive but wettable surfaces that facilitate the crystallization of 6,13-bis(tri-isopropylsilylethynyl)pentacene(TIPS-PEN) and 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene(TIPS-TAP). As evidenced by the presence of ambipolar behavior in TIPS-PEN single crystals and the high electron mobility(2.3 ± 0.34 cm^(2)V^(-1)s^(-1)) in TIPS-TAP single crystals, a general improvement on electron transport with PE interfacial dielectric layers is revealed, which likely associates with the chemically inertness of the saturated C-H bonds. With the advantages in both processing and device operation, the PE interfacial dielectric layer potentially offers a monolithic way for the enhancement of electron transport in solution-processed OSSC-based OFETs.

关键词： Polyethylene Interfacial dielectric layer Organic semiconductor Single crystal Organic field-effect transistors

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Significant annealing-induced hardening effect in nanolaminate d-nanotwinne d(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)me dium-entropy alloy by severe cold rolling

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Journal of Materials Science & Technology 2024年第3期170卷 156-166页

作者： Shuqing Yuan Hui Fu Lei Qian Chi Fai Cheung Xu-Sheng Yang State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong polytechnic University Shenzhen research institute Shenzhen 518060China

Due to the easy coarsening caused by poor thermal stability,the verified annealing-induced hardening in nanograined metals can only maintain at a relatively low-temperature *** this study,a nanolam-inated(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)medium-entropy alloy with an average lamellae thickness of∼20 nm embedded by thinner nanotwins was fabricated by severe cold rolling to achieve superior thermal *** with the conventional nanotwinned CrCoNi with nanotwins inside ultra-fined grains,the hier-archical nanolaminated-nanotwinned(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8) exhibits a significant annealing-induced hard-ening effect,i.e.,hardness increasing from∼250 HV in the original specimen to∼500 HV in the cold-rolled status and finally∼630 HV after annealing at 600℃for 1 *** microstructure characterizations reveal that the reduced dislocation density and formation of L1_(2)ordered domain are mainly responsible for such hardening effect,which is facilitated by the effectively suppressed coarsening with annealing temperature,i.e.,slow detwinning process and well-retained low-angle nanolamellar *** coarsening mechanisms from the cold-rolled nanolamellae to the fully recrystallized micro-equiaxed structures under the annealing temperatures ranging from 400 to 800℃ were also elucidated by atomic observations.

关键词： Annealing-induced hardening Thermal stability Nanolaminated-nanotwinned structure CrCoNi Detwinning Grain boundary migration

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