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arXiv 2024年

作者： Ruben, Benjamin S. Tong, William L. Chaudhry, Hamza Tahir Pehlevan, Cengiz Biophysics PhD Program Harvard University CambridgeMA02138 United States School of engineering and Applied Science Center for Brain Sciences Kempner Institute Harvard University CambridgeMA02138 United States School of engineering and Applied Science Center for Brain Sciences Harvard University CambridgeMA02138 United States

Given a budget on total model size, one must decide whether to train a single, large neural network or to combine the predictions of many smaller networks. We study this trade-off for ensembles of random-feature ridge regression models. We prove that when a fixed number of trainable parameters are partitioned among K independently trained models, K = 1 achieves optimal performance, provided the ridge parameter is optimally tuned. We then derive scaling laws which describe how the test risk of an ensemble of regression models decays with its total size. We identify conditions on the kernel and task eigenstructure under which ensembles can achieve near-optimal scaling laws. Training ensembles of deep convolutional neural networks on CIFAR-10 and a transformer architecture on C4, we find that a single large network outperforms any ensemble of networks with the same total number of parameters, provided the weight decay and feature-learning strength are tuned to their optimal values. Copyright © 2024, The Authors. All rights reserved.

关键词： Budget control

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Facile synthesis of copper cobalt sulfide and nickel hydroxide tube-like composites as battery-type active material of energy storage devices

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Journal of Energy Storage 2023年 65卷

作者： Kuo, Tsung-Rong Fitriannisa, Istikhori Chung, Ren-Jei Lin, Kuan-Hsien Yougbaré, Sibidou Lin, Lu-Yin Wu, Yung-Fu International PhD Program in Biomedical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Graduate Institute of Nanomedicine and Medical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan BP 218 11 Nanoro Burkina Faso Department of Chemical Engineering Ming Chi University of Technology New Taipei City24301 Taiwan

Bimetallic sulfide has attracted much attentions as efficient electroactive materials of battery supercapacitor hybrid (BSH), because of numerous redox states, high conductivity and good energy efficiency. Developing composites having excellent chemical and electrochemical properties is necessary to enhance the energy storage features of bimetallic sulfides. In this study, CuCo2S4 and Ni(OH)2 composites (CuCo2S4@Ni(OH)2) are designed on Ni foam via the facial hydrothermal process and chemical bath deposition as the electroactive material of BSH at first time. Effects of Ni(OH)2 amounts on CuCo2S4 on electrochemical and physical properties of CuCo2S4@Ni(OH)2 are investigated. The physical mixed CuCo2S4 and Ni(OH)2 composite is also fabricated to verify synergistic effects of CuCo2S4@Ni(OH)2. A higher specific capacitance (CF) of 1583.9 F/g along with the capacity of 220.0 mAh/g are got for optimal CuCo2S4@Ni(OH)2 electrode, respectively comparing to 831.7 and 1063.3 F/g of CuCoS4 and Ni(OH)2 electrodes. A BSH is fabricated by the CuCo2S4@Ni(OH)2 electrode and the activated carbon electrode. The potential window of 1.6 V and maximum energy density of 32.1 Wh/kg at 1.1 kW/kg are achieved. The CF retention of 78% and Coulombic efficiency higher than 97% in 8000 charge/discharge cycles are also obtained for this BSH. © 2023

关键词： Sulfur compounds

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Quantitative Study of Angiogenesis in Three-Dimensional Matrigel Barrier Using Electric Impedance Measurement Technique

SSRN

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SSRN 2022年

作者： Huang, Chun-Hao Lei, Kin Fong PhD Program in Biomedical Engineering College of Engineering Chang Gung University Taoyuan Taiwan Department of Biomedical Engineering Chang Gung University Taoyuan Taiwan Department of Radiation Oncology Chang Gung Memorial Hospital Linkou Taiwan

Angiogenesis refers to the development of new blood vessels in tumors and is a vital indicator of cancer metastasis which is the major cause of cancer-related deaths. Study of angiogenesis is critical for the development of potential therapeutic strategies of suppressing cancer metastasis. In the current work, a microfluidic device has been developed and was composed of 2 reservoirs connecting with a Matrigel-filled microchannel. The microchannel was mimicked as a biological barrier and embedded with measurement microelectrodes. New blood vessels were successfully induced to extend along the microchannel. Meanwhile, real-time impedance measurement was conducted to quantitatively monitor the angiogenesis process. The results revealed the extension speed of new blood vessels was proportional to chemical induction level, i.e., VEGF concentration. Moreover, angiogenesis was shown to be induced by the VEGF released from cancer cells and significantly correlated to the number of cancer cells. In addition, anti-VEGF suppressor was quantitatively evaluated to study the suppression efficacy of angiogenesis. The current microfluidic device provides a promising tool to study angiogenesis in 3D biological barrier. The impedance technique offers reliable and quantitative evidences for evaluating drug efficacy. Development of angiogenesis analytical platform can potentially lead to develop novel therapeutic strategies of suppressing cancer metastasis. © 2022, The Authors. All rights reserved.

关键词： Diseases

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Characterisation and issues with the use of a conductivity meter to monitor the level of liquid in a cane diffuser bed

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Transactions of the Royal Society of South Africa 2020年第3期75卷 282-294页

作者： Segura Angel, Diana Maritza Fonseca, Rafael F. PhD in Sciences in the Mechanical Engineering Program Brazil University of São Paulo Av. Trab São-Carlense Brazil

The extraction of sucrose in a cane diffuser depends mainly on the percolation rate, and its optimisation requires the monitoring and control of the liquid holdup with the cane bed. However, most conventional methods that measure liquid levels are not suitable for this application. Operators control the observed liquid level through diffusers’ sight glasses, adjusting the spray position according to visual inspections. The method is inefficient, and a more accurate and reliable measurement process should be implemented towards maximising the sucrose extraction. This article proposes a novel methodology that uses conductance measurements as indicators of the liquid level in cane beds. Conductance, observed liquid level and flow rate variations were analysed under several conditions, such as steady and unsteady states. The effects of the main variables on the observed liquid level and their mathematical relationship were assessed for the validation of the measurements, and experimental tests were conducted on a BMA cane diffuser at Maidstone factory in South Africa. The results are reproducible and show conductance can qualitatively characterise a flooded cane bed. © 2020 Royal Society of South Africa.

关键词： cane bed height conductance flooding liquid level variation in operating conditions

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Efficient photodecoloration catalysts, based on ZnO nanoparticles coated in two steps on glass substrates 19

Efficient photodecoloration catalysts, based on ZnO nanopart...

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19th International Conference on Electrical engineering, Computing Science and Automatic Control, CCE 2022

作者： Dominguez-Flores, R. Estrella-Suarez, M.V. Vega-Perez, J. Maldonado, A. Centro de Investigación y de Estudios Avanzados Del I.P.N. Nanoscience and Nanotechnology PhD Program Mexico City Mexico Instituto Tecnológico de Tlalnepantla Department of Electrical Engineering State of Mexico Mexico Sees Centro de Investigación y de Estudios Avanzados Del I.P.N. Department of Electrical Engineering Mexico City Mexico

ISBN: (数字)9781665455084

ISBN: (纸本)9781665455084

ZnO, ZnO:Ag and ZnO:Cu thin coatings were prepared on glass substrates by an innovative dip-coating technique coupled with the addition of ZnO nanoparticles and their structural, morphological and optical properties were investigated. X-ray Diffraction (XRD) analysis revealed the coatinǵs hexagonal wurtzite phase with a preferred (002) plane orientation. The mean crystallite size calculated on the basis of the Debye-Scherrer model was 31 nm and a small dislocation density of 1.04×10-3 nm-2 was obtained, indicating the existence of few lattice defects and good crystallinity. The atomic force microscopy (AFM) observation showed the coatinǵs granular nature composed of spherical nanoparticles with almost homogeneous distribution. The average transmittance in the visible región is around 75-80% and optical bandgap, 3.25 eV, respectively were obtained for our coatings indicating their suitability in photocatalytic applications. UV-vis spectrometry reveals a methylene blue (MB) dye decoloration efficiency of 96% after 180 min using ZnO:Ag (3:3 layers) film. © 2022 IEEE.

关键词： II-VI semiconductors

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Vulnerability Assessment for IoT Nodes Using OpenBTS and Software Defined Radios 3

Vulnerability Assessment for IoT Nodes Using OpenBTS and Sof...

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3rd International Conference on Signal Processing and Information Security, ICSPIS 2020

作者： De Jesus Rugeles Uribe, Jose Guillen, Edward Paul Applied Sciences PhD Program Universidad Militar Nueva Granada Bogotá Colombia Telecommunications Engineering Program Universidad Militar Nueva Granada Bogota Colombia

ISBN: (纸本)9781728189987

Large-scale cyber attacks using IoT devices have increased in recent years. One of the strategies to deal with this problem is the use of penetration test techniques. The aim of this study was to develop a vulnerability assessment for an IoT M2M node that uses GSM technology. A test scenario was designed consisting of a GMS network created using USRP N210 and OpenBTS radios in a multicell configuration. An IoT-GSM node was designed from a sim8001 radio module, used in several M2M devices. The IoT node stores the measurements of the radio bases operational parameters that make up the GSM network. An algorithm for controlling an attacking base radio was designed using the OpenBTS API, which allows the deployment of a 'man in the middle' attack. The entire test deployment can be carried out remotely. Analysis of the results of the measurements obtained lets us understand the attack's behavior in detail and determine the IoT-GSM node's vulnerability. The results obtained show the potential of SDR and OpenBTS technology as penetration test tools to analyze vulnerabilities of IoT systems. © 2020 IEEE.

关键词： Internet of things

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To Sharpen or not to Sharpen? On the Effect of Sharpening Filters Applied to Magnified Images 14

To Sharpen or not to Sharpen? On the Effect of Sharpening Fi...

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14th International Conference on Digital Image Processing, ICDIP 2022

作者： Emmendorfer, Leonardo R. de Olviveira, Vinicius Menezes Schein, Tatiana T. de Jesus, Junior C. Rodriguez, Bárbara D.A. Electrical Energy Processing Department Federal University of Santa Maria 97105-340 Brazil Center for Computational Science Federal University of Rio Grande 96201-900 Brazil Computational Modeling PhD Program Federal University of Rio Grande 96201-900 Brazil Computer Engineering Graduate Program Federal University of Rio Grande 96201-900 Brazil Institute of Mathematics Statistics and Physics Federal University of Rio Grande 96201-900 Brazil

ISBN: (纸本)9781510657564

Super-resolution algorithms aim to produce magnified high-resolution versions from low-resolution images. Some methods, however, are prone to generate blur during the process. Simple sharpening filters are adopted to alleviate this type of artifact. However, the actual effectiveness of this approach is not clear-cut in the literature. This work evaluates the effect of three simple sharpening filters on the quality of images obtained from super-resolution methods. Two metrics were considered in the evaluation: the Peak signal-to-noise ratio (PSNR) metric, and the Learned Perceptual Image Patch Similarity (LPIPS). One of the filters could consistently improve the LPIPS metric of magnified images from diverse benchmark sets on top of seven super-resolution methods. The increments obtained for the perceptual metric seem to occur due to the sharpening effect. Improvements on PSNR values were not as consistent. © 2022 SPIE.

关键词： Quality control

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Comparative Analysis of AD8232 and BioAmp EXG Pill Analog Front-End Devices in ECG Signal Processing

Comparative Analysis of AD8232 and BioAmp EXG Pill Analog Fr...

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IEEE Conference on Systems, Process & Control (ICSPC)

作者： Tanakrit Mamee Panason Manorost Chakkapong Chamroon Kittiya Thunsiri Department of Mechanical Engineering PhD Program in Mechanical Engineering Under the CMU Presidential Scholarship Chiang Mai University Chiang Mai Thailand Faculty of bioscience engineering KU Leuven University Leuven Belgium Biomedical Engineering Institute Chiang Mai University Chiang Mai Thailand Department of Mechanical Engineering Chiang Mai University Chiang Mai Thailand Faculty of Engineering Chiang Mai University Chiang Mai Thailand

The development of compact portable ECG monitoring devices often entails the pursuit of downsizing measurement systems. This objective frequently involves additional efforts, such as custom PCB fabrication for analog front-end systems and exploration of alternative electrode types and configurations. In this study, we investigate the feasibility of using the BioAmp EXG Pill, a miniature commercial analog front-end board, in comparison to the well-established AD8232. Our analysis focuses on comparing ECG signals from five adult subjects, examining both frequency components using the welch estimation method and ECG parameters extracted from time-domain signals. The results reveal that both devices provided similar outcomes in time-domain measurements, with a slightly lower standard deviation observed in the AD8232. In terms of spectral density, both devices proficiently captured low-frequency components within the 0–3 Hz range. However, in higher-frequency domains, the AD8232 demonstrated superior capability in capturing finer frequency details.

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What Role Do Aggregators Play in Power System Security and Resilience?

What Role Do Aggregators Play in Power System Security and R...

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Resilience Week (RWS)

作者： Reiko Matsuda-Dunn Laura Leddy Eliza Hotchkiss Mukesh Gautam Michael Abdelmalak National Renewable Energy Laboratory Golden CO USA Advanced Energy Systems PhD Program Colorado School of Mines Colorado School of Mines Golden CO USA Department of Electrical and Biomedical Engineering University of Nevada at Reno Reno NV USA

Barriers to the participation of distributed energy resources (DERs) in wholesale electricity markets have limited the use of DERs for power system security and resilience. In September 2020, the Federal Energy Regulatory Commission (FERC) approved an order to reduce these barriers. FERC Order No. 2222 enables the participation of DER aggregators in wholesale electricity markets. DERs include renewable generation and technologies that support the integration of renewable generation by increasing grid flexibility and resilience. Requiring wholesale energy markets to allow DER aggregator participation provides a path for DERs to become competitive in these markets. As the contribution from aggregated DERs continues to increase, the aggregator's role in supporting grid security and resilience will become more critical. This paper reviews work that demonstrates how DER aggregators can provide resilience support through technical capabilities, operational strategies, and secure communication architectures. Socioeconomic influences and impacts of aggregators, including implications for social resilience, are presented. In surveying the current state-of-the-art across different but interconnected topics, we illustrate how aggregators can be power system participants that enhance grid security. There is no one-size-fits-all approach to enhancing resilience in a power grid that includes a growing cohort of DER aggregators, but there are many options for aggregators to contribute to a more resilient and secure power grid.

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Probabilistic genotype-phenotype maps reveal mutational robustness of RNA folding, spin glasses, and quantum circuits

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Physical Review Research 2025年第1期7卷 013118-013118页

作者： Anna Sappington Vaibhav Mohanty Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Harvard-MIT Program in Health Sciences and Technology Harvard Medical School Boston Massachusetts 02115 USA and Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Harvard/MIT MD-PhD Program Harvard Medical School Boston Massachusetts 02115 USA and Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Chemistry and Chemical Biology Harvard University Cambridge Massachusetts 02138 USA

Recent studies of genotype-phenotype maps have reported universally enhanced phenotypic robustness to genotype mutations, a feature essential to evolution. Virtually all of these studies make a simplifying assumption that each genotype—represented as a sequence—maps deterministically to a single phenotype, such as a discrete structure. Here we introduce probabilistic genotype-phenotype (PrGP) maps, where each genotype maps to a vector of phenotype probabilities, as a more realistic and universal language for investigating robustness in a variety of physical, biological, and computational systems. We study three model systems to show that PrGP maps offer a generalized framework which can handle uncertainty emerging from various physical sources: (1) thermal fluctuation in RNA folding, (2) external field disorder in the spin-glass ground state search problem, and (3) superposition and entanglement in quantum circuits, which are realized experimentally on IBM quantum computers. In all three cases, we observe a biphasic robustness scaling which is enhanced relative to random expectation for more frequent phenotypes and approaches random expectation for less frequent phenotypes. We derive an analytical theory for the behavior of PrGP robustness, and we demonstrate that the theory is highly predictive of empirical robustness.

关键词： Quantum computers

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