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International Conference on Indoor Positioning and Indoor Navigation (IPIN)

作者： Mathias Pelka Christian Bollmeyer Horst Hellbrück Department of Electrical Engineering and Computer Science Luebeck University of Applied Sciences (LUAS) Germany University of Luebeck Graduate School for Computing in Medicine and Life Sciences Germany

Indoor localization is important for logistics, industrial applications and for several consumer applications. In the area of logistics, e.g. warehouses, localization accuracy within a few meters is desired. Available radio based systems within that accuracy are neither cost effective nor easy to deploy. Distance estimation together with triangulation are one of the standard solutions for localization. In this work, we propose phase measurements between two wireless sensor nodes for distance estimation. We introduce a mathematical model to estimate distances from phase measurements with multiple frequencies and provide a systematic analysis of possible sources of errors. Additionally, we derive requirements, e.g. resolution for a phase measurement unit to achieve a given accuracy. We present measurements for evaluation to confirm our theoretical results. Our implementation comprises a low cost IEEE 802.15.4 hardware with a built-in phase measurement unit. We implement the developed algorithm for distance estimation in our wireless sensor networks and use two wireless sensor nodes to perform a phase measurement. The contributions of the paper comprise a new model for phase measurements to estimate distances and a preliminary evaluation with our hardware.

关键词： Phase measurement Accuracy Estimation Frequency measurement Receivers Wireless sensor networks Indoor navigation

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Custom error control schemes for energy efficient bluetooth sensor networks

Custom error control schemes for energy efficient bluetooth ...

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International Symposium on Telecommunications

作者： Joao H. Kleinschmidt Walter C. Borelli Marcelo E. Pellenz Department of Telematics School of Electrical and Computer Engineering State University of Campinas Sao Paulo Brazil Graduate Program in Computer Science Pontifical Catholic University of Paraná Curitiba Parana Brazil

This paper analyzes the effect of custom error control schemes on the energy efficiency in Bluetooth sensor networks. The energy efficiency metric considers in just one parameter the energy and reliability constraints of the wireless sensor networks. New packet types are introduced using some error control strategies in the AUX1 packet, such as Hamming and BCH codes, with and without CRC for error detection. Two adaptive techniques are proposed that change the error control strategy based on the number of hops traversed by a packet through the network. The performance results are obtained through simulations in a channel with Rayleigh fading for networks with different number of hops, showing that error control can improve the energy efficiency of a Bluetooth-based sensor network.

关键词： Error correction Energy efficiency Bluetooth Wireless sensor networks Media Access Protocol Energy consumption Sensor phenomena and characterization Automatic repeat request Analytical models Cyclic redundancy check

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Deformation of Porous, Nanostructured Silver at Room Temperature and 150 °C

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MRS Online Proceedings Library 2013年第1期1513卷 1-6页

作者： Noiseau, Guillaume Becker, Michael F. Keto, John W. Kovar, Desiderio Materials Science and Engineering Graduate Program The University of Texas at Austin Austin USA Department of Electrical and Computer Engineering The University of Texas Austin USA Department of Physics The University of Texas Austin USA Department of Mechanical Engineering The University of Texas Austin USA

Porous, nanostructured silver samples were produced using a direct-write method where a nanoparticle aerosol consisting of particles with a mean size of approximately 5 nm were accelerated to speeds of approximately 1000 m/sec and impacted onto a translating substrate [1]. The impacting particles have sufficient energy to stick to the substrate, allowing patterned thick films to be directly written from the aerosol without a mask. Unlike other low temperature processing routes for achieving patterned films, no organics are added that can interfere with postdeposition processing. Typical films are 5- 100 μm thick, up to several centimeters long, and have an as-deposited relative densities as high as 70% of bulk Ag. Compression tests were carried out in steps at room temperature and at 150°C under constant displacement rates. Local strain and densification were measured by optical profilometry between each compression step. The results can be used as a starting point to better understand the mechanisms that govern plasticity, creep, and sintering in nanostructured, porous silver at low processing temperatures.

关键词： Ag densification nanoscale

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SINR: Deconvolving Circular SAS Images Using Implicit Neural Representations

arXiv

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arXiv 2022年

作者： Reed, Albert Blanford, Thomas Brown, Daniel C. Jayasuriya, Suren The School of Electrical Computer and Energy Engineering Arizona State University United States The Applied Research Laboratory United States The Applied Research Laboratory Graduate Program in Acoustics Pennsylvania State University United States The School of Arts Media and Engineering The School of Electrical Computer and Energy Engineering Arizona State University United States

Circular synthetic aperture sonars (CSAS) capture multiple observations of a scene to reconstruct high-resolution images. We can characterize resolution by modeling CSAS imaging as the convolution between a scene's underlying point scattering distribution and a system-dependent point spread function (PSF). The PSF is a function of the system bandwidth and determines a fixed degree of blurring on reconstructed imagery. In theory, deconvolution overcomes bandwidth limitations by reversing the PSF-induced blur and recovering the scene's scattering distribution. However, deconvolution is an ill-posed inverse problem and sensitive to noise. We propose an optimization method that leverages an implicit neural representation (INR) to deconvolve CSAS images. We highlight the performance of our SAS INR pipeline, which we call SINR, by implementing and comparing to existing deconvolution methods. Additionally, prior SAS deconvolution methods assume a spatially-invariant PSF, which we demonstrate yields subpar performance in practice. We provide theory and methods to account for a spatially-varying CSAS PSF, and demonstrate that doing so enables SINR to achieve superior deconvolution performance on simulated and real acoustic SAS data. We provide code (click here) to encourage reproducibility of research. © 2022, CC BY.

关键词： Optical transfer function

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On the Perception of Transients: Applying Psychophysical Constraints to Improve Audio Analysis and Synthesis 26

On the Perception of Transients: Applying Psychophysical Con...

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26th International computer Music Conference, ICMC 2000

作者： Wakefield, Gregory H. Heller, Laurie M. Carney, Laurel H. Mellody, Maureen Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States Naval Submarine Medical Research Laboratory GrotonCT06359 United States Hearing Research Center Dept. of Biomedical Engineering Boston University BostonMA02215 United States Applied Physics Program University of Michigan United States

In a psychophysical experiment, a wideband, 4-ms noise is compared with spectrally smoothed versions of the noise. To isolate on the magnitude spectrum, the phase spectrum is controlled by assigning the same random phase spectrum to both the original and smoothed signals. Depending on the choice of phase spectrum, discrimination thresholds for spectral shape vary from a maximum spectral deviation of 2-3 dB to as much as 25 dB. The exact source of this effect remains an open question. However, it suggests that not all transients require the same signal fidelity. Given a proper characterization of the perceptual response, it may be possible to reduce the size of the codebook required to maintain acceptable perceptual results. © 2000 ICMC. All Rights Reserved.

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A fuzzy inference system to determine the number of clones in the clonal selection algorithm

A fuzzy inference system to determine the number of clones i...

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World Congress on Nature & Biologically Inspired Computing (NaBIC)

作者： Luiz Antonio Carraro Leandro Nunes de Castro Angelita Maria de Ré Computer and Informatics Faculty & Graduate Program in Electrical Engineering Mackenzie University São Paulo Brazil Computer Science Department State University of West-Center Parana Guarapuava Brazil

Artificial Immune Systems (AISs) are composed of techniques inspired by immunology. The clonal selection principle ensures the organism adaptation to fight invading antigens by an immune response activated by the binding of antigens and antibodies. As an immune response can be elicited even when the binding between an antigen and an antibody is not perfect, an approximate binding might suffice, and a Fuzzy Logic mechanism might be the most appropriate mechanism to control such process. This paper presents a novel hybrid model based on concepts of Immune and Fuzzy Systems with applications to pattern recognition problems. The preliminary results obtained here suggest the proposed model is a promising pattern recognition tool.

关键词： Variable speed drives Animals

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Lattice vibration modes in type-II superlattice InAs/GaSb with no-common-atom interface and overlapping vibration spectra

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Physical Review B 2015年第23期91卷 235317-235317页

作者： Henan Liu Naili Yue Yong Zhang Pengfei Qiao Daniel Zuo Ben Kesler Shun Lien Chuang Jae-Hyun Ryou James D. Justice Russell Dupuis Optical Science and Engineering Graduate Program University of North Carolina at Charlotte Charlotte North Carolina USA Department of Electrical and Computer Engineering University of North Carolina at Charlotte Charlotte North Carolina USA Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Champaign Illinois USA Center for Compound Semiconductors and School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta Georgia USA

Heterostructures like InAs/GaSb superlattices (SLs) are distinctly different from well-studied ones like GaAs/AlAs SLs in terms of band alignment, common interface atom, and phonon spectrum overlapping of the constituents, which manifests as stark differences in their electronic and vibrational properties. This paper reports a comprehensive examination of all four types of phonon modes (confined, quasiconfined, extended, and interface) that have long been predicted for the InAs/GaSb SL, with the observation and interpretation of a set of phonon modes by performing cleaved edge μ-Raman study with polarization analysis. Furthermore, we show a signature of symmetry reduction from D2d for GaAs/AlAs SL to C2v for InAs/GaSb SL revealed as a phonon-polariton effect.

关键词： SUPERLATTICES HETEROJUNCTIONS VIBRATIONAL spectra PHONON spectra RAMAN spectroscopy

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Overcoming the surface paradox: Buried perovskite quantum dots in wide-bandgap perovskite thin films

arXiv

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arXiv 2025年

作者： Zhang, Hao Pasha, Altaf Metcalf, Isaac Zhou, Jianlin Staunstrup, Mathias Zhu, Yunxuan Liao, Shusen Ssennyimba, Ken Chen, Jia-Shiang Reddy, Surya Prakash Thébaud, Simon Hou, Jin Shuai, Xinting Mandani, Faiz Sidhik, Siraj Jones, Matthew R. Ma, Xuedan Balakrishna, R. Geetha Susarla, Sandhya Ginger, David S. Katan, Claudine Kanatzidis, Mercouri G. Bawendi, Moungi G. Natelson, Douglas Tamarat, Philippe Lounis, Brahim Even, Jacky Mohite, Aditya D. Department of Chemical and Biomolecular Engineering Rice University HoustonTX77005 United States Applied Physics Program Smalley‐Curl Institute Rice University HoustonTX77005 United States Centre for Nano and Material Sciences Jain University Jain Global Campus Kanakapura Karnataka Bangalore562112 India Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Université de Bordeaux LP2N Talence France Institut d’Optique CNRS LP2N Talence France Department of Physics and Astronomy Rice University HoustonTX77005 United States Center for Nanoscale Materials Argonne National Laboratory LemontIL60439 United States School for Engineering of Matter Transport and Energy Arizona State University TempeAZ85281 United States UMR 6082 CNRS INSA de Rennes Rennes35708 France Department of Chemistry Rice University HoustonTX77005 United States Department of Chemistry University of Washington Box 351700 SeattleWA98195-1700 United States UMR 6226 Rennes35000 France Department of Chemistry Northwestern University EvanstonIL United States Department of Chemistry Massachusetts Institute of Technology 77 Massachusetts Avenue CambridgeMA02139 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States

Colloidal perovskite quantum dots (PQDs) are an exciting platform for on-demand quantum, and classical optoelectronic and photonic devices. However, their potential success is limited by the extreme sensitivity and low stability arising from their weak intrinsic lattice bond energy and complex surface chemistry. Here we report a novel platform of buried perovskite quantum dots (b-PQDs) in a three-dimensional perovskite thin-film, fabricated using one-step, flash annealing, which overcomes surface related instabilities in colloidal perovskite dots. The b-PQDs demonstrate ultrabright and stable single-dot emission, with resolution-limited linewidths below 130 μeV, photon-antibunching (g2(0)=0.1), no blinking, suppressed spectral diffusion, and high photon count rates of 104/s, consistent with unity quantum yield. The ultrasharp linewidth resolves exciton fine-structures (dark and triplet excitons) and their dynamics under a magnetic field. Additionally, b-PQDs can be electrically driven to emit single photons with 1 meV linewidth and photon-antibunching (g2(0)=0.4). These results pave the way for on-chip, low-cost single-photon sources for next generation quantum optical communication and sensing. © 2025, CC BY.

关键词： Photons

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Highly efficient (11.1%) small molecule multi-junction organic photovoltaic cells

Highly efficient (11.1%) small molecule multi-junction organ...

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2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)

作者： Xiaozhou Che Xin Xiao Stephen R. Forrest Applied Physics Program University of Michigan Ann Arbor MI USA Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

We present multi-junction small molecule organic photovoltaic (OPV) cells with efficiencies over 11%. The devices consist of two or three, vacuum thermally evaporated planar-mixed heterojunction sub-cells with minimal absorption overlap between the cells. By introducing a transparent interconnecting layer, a dual element (tandem) cell achieves a power conversion efficiency of 10.0 ± 0.5%. We further improve the cell performance by adding an additional (3 rd ) sub-cell that absorbs at the second order optical interference maximum within the stack. The triple-junction cell significantly improves the quantum efficiency at shorter wavelengths, achieving a power conversion efficiency of 11.1 ± 0.5%, which to our knowledge, is the highest reported for a multi-junction OPV cell in the scientific literature.

关键词： Absorption Photovoltaic cells Interference Adaptive optics Cathodes Current measurement Optical filters

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Total variation superiorized conjugate gradient method for image reconstruction

arXiv

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arXiv 2017年

作者： Zibetti, Marcelo V. W. Lin, Chuan Herman, Gabor T. Graduate Program in Electrical Engineering and Computer Science Federal University of Technology - Paraná Curitiba80230-901 Brazil School of Electrical Engineering Southwest Jiaotong University Chengdu Sichuan610031 China Department of Computer Science Graduate Center City University of New York New YorkNY10016 United States

The conjugate gradient (CG) method is commonly used for the relatively-rapid solution of least squares problems. In image reconstruction, the problem can be ill-posed and also contaminated by noise;due to this, approaches such as regularization should be utilized. Total variation (TV) is a useful regularization penalty, frequently utilized in image reconstruction for generating images with sharp edges. When a non-quadratic norm is selected for regularization, as is the case for TV, then it is no longer possible to use CG. Nonlinear CG is an alternative, but it does not share the efficiency that CG shows with least squares and methods such as fast iterative shrinkage-thresholding algorithms (FISTA) are preferred for problems with TV norm. A different approach to including prior information is superiorization. In this paper it is shown that the conjugate gradient method can be superiorized. Five different CG variants are proposed, including preconditioned CG. The CG methods superiorized by the total variation norm are presented and their performance in image reconstruction is demonstrated. It is illustrated that some of the proposed variants of the superiorized CG method can produce reconstructions of superior quality to those produced by FISTA and in less computational time, due to the speed of the original CG for least squares problems. In the Appendix we examine the behavior of one of the superiorized CG methods (we call it S-CG);one of its input parameters is a positive number ". It is proved that, for any given " that is greater than the half-squared-residual for the least squares solution, S-CG terminates in a finite number of steps with an output for which the half-squared-residual is less than or equal to ". Importantly, it is also the case that the output will have a lower value of TV than what would be provided by unsuperiorized CG for the same value " of the half-squared residual. Copyright © 2017, The Authors. All rights reserved.

关键词： Conjugate gradient method

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