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Exploring spherical units as perceptual clues in enumerating 3d arrays

MATHEMATICS EdUCATION RESEARCH JOURNAL 2024年第3期36卷 671-693页

作者： Alstad, Edgar Berre, Maren Nilsson, Per Nord Univ Levanger Norway Linnaeus Univ Linnaeus Sweden

This study continues an investigation of how spherical units, compared to cubical units, can facilitate students' units-locating and organizing units in composites. We analyze how Norwegian grade 3 students enumerate 3d arrays with cubical and spherical units. Our results show how spherical units can act as perceptual clues that facilitate cognitive processes, underlying students' strategies in the enumeration of 3d arrays. In particular, the results show how spherical units facilitate the units-locating process, which, in turn, supports processes of organizing-by-composites and spatial structuring of the array, in the action of developing a proper iterative strategy such as layer-based thinking.

关键词： Perceptual clues Enumerating units 3d arrays Spherical units

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Exploring units-locating in enumerating units of 3d arrays: linking units-locating to units-representation

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MATHEMATICS EdUCATION RESEARCH JOURNAL 2023年第3期35卷 583-605页

作者： Alstad, Edgar Berre, Maren Nilsson, Per Nord Univ Levanger Norway Orebro Univ Orebro Sweden

The aim of the present study is to explore strategies in enumerating units of three dimensional (3d) arrays. We analyse enumeration strategies of students in grade 3 (ages 8 to 9) in situations of cubical and spherical representations of units of 3d arrays. By exploring students' strategies in these two situations, we find that difficulties in enumerating units in 3d arrays can be traced to difficulties in units-locating, with the consequence of applying double and triple counting. Our results also indicate that spherical units can serve as perceptual clues in units-locating and in assembling units into relevant composites. With input from our findings, we suggest research to investigate the following three hypotheses: (i) spherical units can turn students away from double and triple counting, (ii) spherical units can support students' units-locating process and their ability to assemble units into relevant composites and (iii) teaching of enumerating 3d arrays should start with spherical units before cubical units.

关键词： 3d arrays Units-locating Enumerating Perceptual clues Units-representation

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design of 2d and 3d differential Microphone arrays With a Multistage Framework

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IEEE-ACM TRANSACTIONS ON AUdIO SPEECH ANd LANGUAGE PROCESSING 2023年 31卷 2016-2031页

作者： Zhao, Xudong Huang, Gongping Chen, Jingdong Benesty, Jacob Northwestern Polytech Univ Ctr Intelligent Acoust & Immers Commun Xian 710072 Peoples R China Northwestern Polytech Univ Shaanxi Prov Key Lab Artificial Intelligence Xian 710072 Peoples R China Wuhan Univ Sch Elect Informat Wuhan 430072 Peoples R China Univ Quebec INRS EMT Montreal PQ H5A 1K6 Canada

differential microphone arrays (dMAs) have demonstrated a great potential for high-fidelity acoustic and speech signal acquisition in a wide range of applications since such arrays are able to achieve frequency-invariant beampatterns with high directivity. Consequently, a great number of efforts have been devoted to the design of dMAs and the associated beamformers in the literature. However, most of the methods only work for arrays with particular topologies, e.g., linear, circular, concentric circular, and spherical ones. How to design general two-dimensional (2d) and three-dimensional (3d) dMAs that can measure the desired differential sound field and form the desired spatial response in the 3d space remains an unsolved problem. This article investigates this problem and presents a multistage design approach. The major contributions of this work are as follows. First, we reexamine the differentials of the acoustic pressure field in the 3d space and derive the general expression of the directivity patterns resulting from the spatial differential operation, which serves as the foundation for differential beamforming with 2d or 3d microphone arrays. Second, we present a multistage approach to the design of 2d and 3d dMAs, and deduce the relationship between the global beamformer and the beamformers at different stages as well as the relationship between their beampatterns. Third, several algorithms are presented for the design of differential as well as robust differential beamformers in this multistage framework. Simulation results validate the proposed approach and justifies its properties.

关键词： Three-dimensional displays Array signal processing Acoustics Microphone arrays Speech processing Acoustic arrays Shape differential beamforming microphone arrays beampattern 2d arrays 3d arrays

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A 3d hierarchical TiO2/CaIn2S4/C3N4 arrays photoanode with dual-heterojunction for enhanced photoelectrochemical performance

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NANOTECHNOLOGY 2024年第15期35卷 155402-155402页

作者： Zhang, Wei Zhang, Xing Zhang, Lina Ma, Jinwen Yin, Xiaotong Tian, Yuxin Wang, Chuang Wang, Qiushi Bohai Univ Coll Phys Sci & Technol Jinzhou 121013 Peoples R China Bohai Univ Inst Ocean Res Jinzhou 121013 Peoples R China Bohai Univ Coll Chem & Mat Engn Jinzhou 121013 Peoples R China

A novel 3d hierarchical TiO2/CaIn2S4/C3N4 arrays with dual heterojunctions photoanode is constructed by stepwise deposition of CaIn2S4 nanosheets and ultrathin C3N4 onto the well-aligned TiO2 nanorods arrays. Integrating the merit of the superior ability of CaIn2S4 and C3N4 to harvest visible light, dual type-II heterojunction band structure and one-dimensional ordered nanostructures, the TiO2/CaIn2S4/C3N4 photoanode exhibits simultaneous significant improvements in visible-light harvesting, charge separation and electron transfer capability. At 1.23 V (versus reversible hydrogen electrode) under AM 1.5 G irradiation, the TiO2/CaIn(2)S(4)75/C3N4 photoanode exhibits a photocurrent density of 4.5 mA cm(-2), which is 5.2 and 51.1-fold higher than that of TiO2/CaIn(2)S(4)75 and pristine TiO2 photoanode, respectively. Moreover, the applied bias photo-to-current efficiency (ABPE) of the TiO2/CaIn(2)S(4)75/C3N4 photoanode reaches 3.5% at 0.36 V (versus reversible hydrogen electrode). These results are helpful for fabricating more efficient heterostructure photoelectrodes.

关键词： hierarchical heterostructures 3d arrays dual-heterojunction photoelectrochemical

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Magnetic field induced controllable self-assembly of maghemite nanocrystals: From 3d arrays to 1d nanochains

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APPLIEd SURFACE SCIENCE 2015年 347卷 202-207页

作者： Tang, Yan Chen, Qianwang Chen, Rongsheng Wuhan Univ Sci & Technol Sch Chem Engn & Technol Wuhan 430081 Peoples R China Univ Sci & Technol China Hefei Natl Lab Phys Sci Microscale Hefei 230026 Peoples R China Univ Sci & Technol China Dept Mat Sci & Engn Hefei 230026 Peoples R China

A hydrothermal process has been used to synthesize walnut-like maghemite superstructures which can be further self-assembled in a controllable manner into ordered three-dimensional (3d) architectures and one-dimensional (1d) nanochains in the presence of different external magnetic field. The assembly behavior of the maghemite nanoparticles isclosely related to the van der Waals interactions and external field-induced magnetic dipole interactions. The magnetic properties of these nanostructures are also investigated. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Maghemite Magnetic field Self-assembly 3d arrays 1d nanochains

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durian-Inspired design of Bismuth-Antimony Alloy arrays for Robust Sodium Storage

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ACS NANO 2020年第7期14卷 9117-9124页

作者： Ni, Jiangfeng Li, Xinyan Sun, Menglei Yuan, Yifei Liu, Tongchao Li, Liang Lu, Jun Soochow Univ Ctr Energy Convers Mat & Phys CECMP Sch Phys Sci & Technol Suzhou 215006 Peoples R China Argonne Natl Lab Chem Sci & Engn Div Lemont IL 60439 USA

Sodium-ion batteries have attracted widespread attention for cost-effective and large-scale electric energy storage. However, their practical deployment has been largely retarded by the lack of choice of efficient anode materials featuring large capacity and electrochemical stability and robustness. Herein, we report a durian-inspired design and template-free fabrication of a robust sodium anode based on triangular pyramid arrays of Bi0.75Sb0.25 alloy electrodeposited on Cu substrates. The Bi0.75Sb0.25 arrays exhibit an appreciable electrochemical robustness for sodium storage, sustaining a reversible capability 335 mAh g(-1) at a high rate of 2.5 A g(-1) and 87% of the initial capacity over 2000 cycles. We further demonstrate the applicability of the Bi0.75Sb0.25 array anode in sodium full cells by pairing it with a Na3V2(PO4)(3)/C cathode. This full cell achieves a high specific energy of 203 Wh kg(-1) (based on both active electrodes). Such an enhanced performance is attributed to the thorny-durian-like architecture and bimetallic alloy composition. The pyramid tip induces ion enrichment for rapid charge-transfer reaction, while the alloy design reduces the electrode volume swelling for stable Na cycling.

关键词： sodium-ion battery anode bismuth antimony 3d arrays

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Solar-driven All-in-One Interfacial Water Evaporator Based on Electrostatic Flocking

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AdVANCEd SUSTAINABLE SYSTEMS 2021年第1期5卷

作者： Guo, Yang Javed, Muhammad Li, Xiaoyan Zhai, Shixiong Cai, Zaisheng Xu, Bi Donghua Univ Coll Chem Chem Engn & Biotechnol Natl Engn Res Ctr Dyeing & Finishing Text 2999 North Renmin Rd Shanghai 201620 Peoples R China

Solar-driven interfacial water evaporation is a promising strategy to produce clean water by effectively converting abundant solar energy into localized heat. However, many previously reported interfacial evaporation systems are separate and costly. In this work, an all-in-one interfacial water evaporator with flexibility, low-cost, and large-scale production based on electrostatic flocking technology is proposed. Hydrophilic microfibers (flocks) are vertically planted on the upper side of the textile substrate to enhance the light trapping for photothermal conversion and lower the latent heat for more efficient evaporation. On the other side of the textile, a highly dense and vertically aligned array of hydrophobic flocks are prepared to form a continuous air layer, reducing heat conduction from absorber to bulk water. Taking advantage of those features, the all-in-one evaporator achieves a good evaporation rate of 1.32 kg m(-2)h(-1)for pure water and 1.10 kg m(-2)h(-1)for seawater. Simultaneously, the evaporator demonstrates resistance to salt accumulation, resulting in its stability in brine. This all-in-one evaporator represents an innovative way for designing interfacial evaporators and a convenient approach to mitigate the global freshwater scarcity.

关键词： 3d arrays electrostatic flocking interfacial heat management water purification solar-driven water evaporation

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3d V-shaped Array design for Fully Isotropic Azimuth and Elevation Angle Estimation 27

3D V-shaped Array Design for Fully Isotropic Azimuth and Ele...

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27th Signal Processing and Communications Applications Conference (SIU)

作者： Keskin, Fesih Filik, Tansu Igdir Univ Elekt Elekt Muhendisligi Igdir Turkey Eskisehir Tekn Univ Elekt Elekt Muhendisligi Eskisehir Turkey

ISBN: (纸本)9781728119045

In this study, a new approach for designing a three dimensional (3d) V-shaped antenna array is proposed, which has fully isotropic azimuth and elevation direction of Arrival (dOA) estimation. The proposed method results in a 3d array by adding additional antenna on the given planar V-shaped array to provide the constraints of equalizing the auto-moments and setting the cross-moments to zero. The performance of the designed 3d V-shaped antenna array is compared to the different arrays.

关键词： Array signal processing 2d direction of arrival estimation 3d arrays Isotropic arrays

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A green approach for self-assembly of Ag-Au nanoparticles into 3-d arrays

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MATERIALS LETTERS 2017年 186卷 311-313页

作者： Zamora-Mendoza, M. T. Luis Lopez-Miranda, J. Rosas, G. UMSNH Inst Invest Met Edificio UCiudad Univ Morelia 58060 Michoacan Mexico

In this investigation, we report the formation of new 3-d aggregates consisting of Ag-Au nanoparticles obtained in aqueous solution by a facile method using Aloysia triphylla plant extract as a reducing and stabilizing agent. SEM and EdS analysis reveal that the dimensions of 3-d arrays are estimated to be about 2.5 mu m wide, 0.5 mu m thick, and 2 mu m long. The 3-d geometric aggregates have strong microstructures that are similar to those of ordinary crystalline materials. The microstructures are close-packed with straight edges and facets but do not have grain boundaries. HRTEM images indicate that the 3-d arrays are a consequence of the nanoparticles aggregation inside an organic matrix and the presence of Au forming the BNPs.

关键词： Nanoparticles Ag-Au Electron microscopy Green synthesis Self-assembly 3d arrays

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ZnO-(Cu/Ag)TCNQ heterostructure network over flexible platform for enhanced cold cathode application

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NANOTECHNOLOGY 2016年第26期27卷 265601-265601页

作者： Pal, Shreyasi Maiti, Soumen Maiti, Uday Narayan Chattopadhyay, Kalyan Kumar Jadavpur Univ Dept Phys Thin Films & Nanosci Lab Kolkata 700032 India Indian Inst Technol Dept Phys Gauhati 781039 India St Thomas Coll Engn & Technol Kolkata 700023 India

Multistage field emitters consisting of organic/inorganic hybrid nanostructures with branched geometry are designed via a two-step protocol: a simple wet chemical method followed by a vapor-solid-phase technique. (Cu/Ag)TCNQ (copper/silver-7,7,8,8-tetracyanoquinodimethane) nanowires (NWs) were grown hierarchically on zinc oxide (ZnO) nanorods (NRs) to form ZnO-(Cu/Ag) TCNQ heterostructure assemblies. By monitoring the metallic Cu and Ag coating thickness on ZnO NRs, precise control over the morphology and orientations of the secondary organic NWs is achieved. In-depth analysis of electron field emission (FE) behavior of the ZnO-(Cu/Ag) TCNQ-based hierarchy suggests highest emission performance with low turn-on as well as threshold fields of 1.15 and 3.75 V mu m(-1) respectively from the morphology-optimized hierarchy. Beneficial orientation of the branched organic NWs ensures sequential electric field enhancement in the consecutive stem and branches whereas its low work function eases electron emission;these aspects combined together render an overall enhancement in the emission behavior of the hybrid system. As compared to individual building units, the heterostructures show improved field electron emission. Additionally, successful construction of this novel hybrid over a fabric platform displays great potential in opening up new pathways in the highly-anticipated field of flexible electronics.

关键词： organic/inorganic heterostructures multistage field emitters flexible substrate 3d arrays

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