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Photonics research 2019年第6期7卷 I0026-I0033页

作者： ANDrEW M.ArMSTrONG BrIANNA A.KLEIN ANDrEW A.ALLErMAN ALBErT G.BACA MArY H.CrAWFOrD JACOB PODKAMINEr carlos r.perez MICHAEL P.SIEGAL ErICA A.DOUGLAS VINCENT M.ABATE FrANCOIS LEONArD Sandia National Laboratories Albuquerque New Mexico 87185 USA Current address: 3M Corporate research Labs St. Paul Minnesota 55144 USA Sandia National Laboratories Livermore California 94550 USA

AlGaN-channel high electron mobility transistors(HEMTs) were operated as visible-and solar-blind photodetectors by using GaN nanodots as an optically active floating gate. The effect of the floating gate was large enough to switch an HEMT from the off-state in the dark to an on-state under illumination. This opto-electronic response achieved responsivity >10^8 A∕W at room temperature while allowing HEMTs to be electrically biased in the offstate for low dark current and low DC power dissipation. The influence of GaN nanodot distance from the HEMT channel on the dynamic range of the photodetector was investigated, along with the responsivity and temporal response of the floating gate HEMT as a function of optical intensity. The absorption threshold was shown to be controlled by the AlN mole fraction of the HEMT channel layer, thus enabling the same device design to be tuned for either visible-or solar-blind detection.

关键词： photodetectors high electron mobility transistors

L^1→L^q Poincare Inequalities for 0representation Formulas

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Acta Mathematica Sinica,English Series 2002年第1期18卷 1-20页

作者： perez carlos Departamento dr Matematicas. Universidad Autónoma de Madrid. 28049 Madrid. Spain

Civen two doubling measures μ and v in a metric apace (S.p)of homogeneous type. let B_0 S be a given ball. It has been a well-known result bv now (see)[1 4])theat the validity of an L^1→L^1 Poincaré inequality of the following form: f_B|f-f_B|dv≤cr(B)f_Bgdμ. for all metric balls B B_0 S, implies a variant of representation formula of fractonal integral type: |f(x)-f_(B(11))|≤C integral from n=B_(11) g(y)p(x, y)/μ(B(x, p(x, y)))dμ(y)+C(r(B_0))/(μ(B_0))integral from n=B_0 g(y)dμ(y). One of the main results of this paper shows that an L^1 to L^q Poincaré inequality for some 01, i.e.. (f_B|f-f_B|~q dv)^(1/q)≤cr(B) f_B gdμ, for all metric balls B B_0. will suffice to imply the above representation formula. As an immediate corollary, we can show that the weak-type condition. sup_(λ>0)(λv({x ∈ B:|f(x)-f_B|>λ}))/v(B)≤Gr (B)f_B gdμ. also implies the same formula. Analogous theorems related to high-order Poincaréinequalities and Sobolev spaces in metric spaces are also proved.

关键词： Sobolev spaces representation formulas High-order derivatives Vector fields Metric spaces Polynomials Doubling measures Poincare inequalities

An unsupervised pattern recognition methodology based on factor analysis and a genetic-DBSCAN algorithm to infer operational conditions from strain measurements in structural applications

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Chinese Journal of Aeronautics 2021年第2期34卷 165-181页

作者： Juan carlos PErAFAN-LOPEZ Julian SIErrA-perez Grupo de Investigacion en Ingenieria Aeroespacial Universidad Pontificia BolivarianaCircular 170-01Medellin 050031Colombia

Structural Health Monitoring(SHM) suggests the use of machine learning algorithms with the aim of understanding specific behaviors in a structural system. This work introduces a pattern recognition methodology for operational condition clustering in a structure sample using the well known Density Based Spatial Clustering of Applications with Noise(DBSCAN) *** methodology was validated using a data set from an experiment with 32 Fiber Bragg Gratings bonded to an aluminum beam placed in cantilever and submitted to cyclic bending loads under 13 different operational conditions(pitch angles). Further, the computational cost and precision of the machine learning pipeline called FA + GA-DBSCAN(which employs a combination of machine learning techniques including factor analysis for dimensionality reduction and a genetic algorithm for the automatic selection of initial parameters of DBSCAN) was measured. The obtained results have shown a good performance, detecting 12 of 13 operational conditions, with an overall precision over 90%.

关键词： Clustering DBSCAN Factor analysis FBGs Pattern recognition Strain field

Generalized Multiscale rBF Networks and the DCT for Breast Cancer Detection

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International Journal of Automation and computing 2020年第1期17卷 55-70页

作者： carlos Beltran-perez Hua-Liang Wei Adrian rubio-Solis Department of Automatic Control and Systems Engineering University of SheffieldSheffield S13JDUK Tecnologico de Monterrey Campus TolucaEduardo Monroy Cardenas 2000San Antonio BuenavistaToluca 50110Mexico

The use of the multiscale generalized radial basis function(MSrBF)neural networks for image feature extraction and medical image analysis and classification is proposed for the first time in this *** MSrBF networks hold a simple and flexible architecture that has been successfully used in forecasting and model structure detection of input-output nonlinear *** this work instead,MSrBF networks are part of an integrated computer-aided diagnosis(CAD)framework for breast cancer detection,which holds three stages:an input-output model is obtained from the image,followed by a high-level image feature extraction from the model and a classification module aimed at predicting breast *** the first stage,the image data is rendered into a multiple-input-single-output(MISO)*** order to improve the characterisation,the nonlinear autoregressive with exogenous inputs(NArX)model is introduced to rearrange the available input-output data in a nonlinear *** forward regression orthogonal least squares(FrOLS)algorithm is then used to take advantage of the previous arrangement by solving the system as a model structure detection problem and finding the output layer weights of the NArX-MSrBF *** the second stage,once the network model is available,the feature extraction takes place by stimulating the input to produce output signals to be compressed by the discrete cosine transform(DCT).In the third stage,we leverage the extracted features by using a clustering algorithm for classification to integrate a CAD system for breast cancer *** test the method performance,three different and well-known public image repositories were used:the mini-MIAS and the MMSD for mammography,and the BreaKHis for histopathology images.A comparison exercise was also made between different database partitions to understand the mammogram breast density effect in the performance since there are few remarks in the literature on this *** results show that

关键词： Nonlinear system identification image processing discrete cosine transform radial basis functions computer-aided diagnosis neural networks

Memory for location and visual cues in white-eared hummingbirds Hylocharis leucotis

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Current Zoology 2011年第4期57卷 468-476页

作者： Guillermo perez carlos LArA Jose VICCON-PALE Martha SIGNOrET-POILLON Doctorado en Ciencias Biologicas Universidad Autonoma Metropolitana. Unidad Xochimilco. Calzada del Hueso 1100 Col. Villa Quietud 04960 Moxico D.F. Moxico Laboratorio de Ecologfa de la Conducta Centro Tlaxcala de Biologfa de la Conducta UAT-UNAM Km 1.5 carretera Tlaxcala- Puebla s/n Colonia Xicohtoncatl Apdo. Postal 262 Tlaxcala Tlaxcala 90070 Moxico. Departamento el Hombre y su Ambiente. Universidad Autdnoma Metropolitana. Unidad Xochimilco. Calzada del Hueso 1100 Col. Villa Quietud 04960 MExico D.F. Mexico

In nature hummingbirds face floral resources whose availability, quality and quantity can vary spatially and temporally. Thus, they must constantly make foraging decisions about which patches, plants and flowers to visit, partly as a function of the nectar reward. The uncertainty of these decisions would possibly be reduced if an individual could remember locations or use visual cues to avoid revisiting recently depleted flowers. In the present study, we carried out field experiments with white-eared hummingbirds Hylocharis leucotis, to evaluate their use of locations or visual cues when foraging on natural flowers Penstemon roseus. We evaluated the use of spatial memory by observing birds while they were foraging between two plants and within a single plant. Our results showed that hummingbirds prefer to use location when foraging in two plants, but they also use visual cues to efficiently locate unvisited rewarded flowers when they feed on a single plant. However, in absence of visual cues, in both experiments birds mainly used the location of previously visited flowers to make subsequent visits. Our data suggest that hummingbirds are capable of learning and employing this flexibility depending on the faced environmental conditions and the information acquired in previous visits [Current Zoology 57 （4）： 468-476, 2011].

关键词： Visual cues Location White-eared hummingbird Foraging

Zeta potential measurement on lithium lanthanum titanate nanoceramics

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Particuology 2016年第1期14卷 69-72页

作者： carlos ricardo Milian Pila Eduardo perez Cappe Yodalgis Mosqueda Laffita Oswaldo Luiz Alves Institute of Materials Science and Technology (IMrE) Havana University Havana CP 10400 Cuba Solid state Chemistry Laboratory Institute of Chemistry Campinas University Campinas CP 13083-970 SP Brazil

The zeta potential, isoelectric point, and agglomeration of ***3 （LLTO） nanoparticles dispersed in aqueous media at different ionic strengths have been studied. The zeta potential was determined from electrophoretic mobility measurements, according to Smoluchowski＇s equation, for Li0.5La0.5TiO3 suspen- sions in NaCl and KCI electrolytes with ionic strengths of 1, 10, and 100 mmol/dm3. The isoelectric point （IEP）, zeta potential （ζ）, and the agglomeration were shown to strongly depend on the ionic strength of the Li0.5La0.5TiO3 aqueous colloidal suspension in both NaCI and KCI electrolytes, which allows the deter- mination of the effects of environmental conditions for ***3 manipulation in aqueous colloidal systems. The suspensions of Li0.5La0.5TiO3 nanoparticles reach the IEP in the pH range 0f3-5. The （ of Li0.5La0.5TiO3 nanoparticles varied from positive to negative values with a pH increase, which allows for the control of the surface charge depending on the purpose. The pH range of 7-g and an ionic strength ≤1 mmol/dm3 are recommended as the most suitable conditions for both the LLTO colloidal shaping techniques application and the LLTO-based nanocomposite formation.

关键词： Titanate Nanoparticles Zeta potential Colloidal suspension

Domain Decomposition for Quasi-Periodic Scattering by Layered Media via robust Boundary-Integral Equations at All Frequencies

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Communications in Computational Physics 2019年第6期26卷 265-310页

作者： carlos perez-Arancibia Stephen P.Shipman Catalin Turc Stephanos Venakides Institute for Mathematical and Computational Engineering School of Engineering and Faculty of MathematicsPontificia Universidad Catlica de ChileSantiagoChile Department of Mathematics Louisiana State UniversityBaton RougeLA 70803USA Department of Mathematical Sciences New Jersey Institute of TechnologyNewarkNJ 07102USA Department of Mathematics Duke UniversityDurhamNC 27708USA

We develop a non-overlapping domain decomposition method(DDM)for scalar wave scattering by periodic layered *** approach relies on robust boun-dary-integral equation formulations of robin-to-robin(rtr)maps throughout the frequency spectrum,including cutoff(or Wood)*** overcome the obsta-cle of non-convergent quasi-periodic Green functions at these frequencies by incor-porating newly introduced shifted Green *** the latter in the defini-tion of quasi-periodic boundary-integral operators leads to rigorously stable computations of rtr *** develop Nystr̈om discretizations of the rtr maps that rely on trigonometric interpolation,singularity resolution,and fast convergent windowed quasi-periodic Green *** solve the tridiagonal DDM system via recursive Schur complements and establish rigorously that this procedure is always completed *** present a variety of numerical results concerning Wood frequencies in two and three dimensions as well as large numbers of layers.

关键词： Helmholtz transmission problem domain decomposition periodic layered media lattice sum

Prognostic utility of NT-proBNP greater than 70,000 pg/mL in patients with end stage renal disease

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Journal of Geriatric Cardiology 2018年第7期15卷 476-478页

作者： Julio perez-Downes carlos Palacio Saif Ibrahim Patrisha Shelley Alan Miller Pramod reddy Division of General Internal Medicine University of Florida College of Medicine-Jacksonville USA Department of Interventional Cardiology University of Alabama Birmingham Birmingham AL USA Division of Cardiology Department ofMedicine University of Florida College of Medicine- Jacksonville USA

Natriuretic peptides are synthesized in ventricular myocytes and released into the circulation in response to increased myocardial wall stress, Causes of myocardial wall stress include pulmonary hypertension, ventricu... 详细信息

关键词： End stage renal disease Heart failure Heart failure reduced ejection fraction Mortality NT-proBNP

Highly accessible aqueous synthesis of well-dispersed dendrimer type platinum nanoparticles and their catalytic applications

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Nano research 2019年第5期12卷 1083-1092页

作者： Adrian Fernandez-Lodeiro Jamila Djafari David Lopez-Tejedor carlos perez-rizquez Benito rodriguez-Gonzalez Jose Luis Capelo Jose M.Palomo carlos Lodeiro Javier Fernandez-Lodeiro BIOSCOPE Group LAQV@REQUIMTEChemistry DepartmentFaculty of Science and TechnologyUniversity NOVA of LisbonCaparica CampusCaparica 2829-516Portugal PrOTEOMASS Scientific Society Rua dos InventoresMadan ParqueCaparica CampusCaparica 2829-516Portugal Department of Biocatalysis Institute of Catalysis(CSIC)MadridSpainMarie Curie 2CantoblancoUAM CampusMadrid 28049Spain Scientific and Technological research Assistance Center(CACTI) University of VigoLagoas-MarcosendeVigo 36310Spain

The application of novel methodologies to the synthesis of nanomaterials is still a challenge in many different technological and scientific *** efficient and reproducible synthetic methodologies,that produce fewer residues and reduce the cost of raw materials must be *** the present work,we have explored the attractive possibility to apply the cheap iron (Ⅱ) sulphate salt in the reduction process of the K2PtCl4 to produce colloids *** synthesis took places in water and was assisted by sodium citrate (SC) using polyvinylpyrrolidone (PVP) as a *** adjustment of this novelty process allows obtaining well-dispersed and sub-20 nm dendrimer-type platinum nanoparticles (Pt D-NPs).The nano-dendrimers produced have been characterized using dynamic light scattering (DLS),transmission electron microscopy (TEM),high-resolution TEM (Hr-TEM),XrD spectroscopy,inductive couple plasma (ICP) analysis,Fourier transform infrared (FT-Ir) and ultraviolet-visible (UV-vis) *** conformational results derived from the size and shape will be *** application of the Pt D-NPs has been explored in the reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) in aqueous media at room temperature obtained TOF value of 253 min^-***,our Pt D-NPs were tested as artificial metalloenzyme showing catechol oxidase activity for oxidation of L-DOPA.

关键词： platinum dendrimer NPs catalytic application green synthesis cateohol oxidase-like activity

Training data selection for accuracy and transferability of interatomic potentials

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npj Computational Materials 2022年第1期8卷 1795-1803页

作者： David Montes de Oca Zapiain Mitchell A.Wood Nicholas Lubbers carlos ZP.ereyra Aidan P.Thompson Danny perez Sandia National Laboratories AlbuquerqueNM87185USA Computer Computationaland Statistical Sciences DivisionLos Alamos National LaboratoryLos AlamosNM87545USA Mechanical and Aerospace Engineering University of California DavisDavisCA95616USA Theoretical Division Los Alamos National LaboratoryLos AlamosNM87545USA

Advances in machine learning(ML)have enabled the development of interatomic potentials that promise the accuracy of first principles methods and the low-cost,parallel efficiency of empirical ***,ML-based potentials struggle to achieve transferability,i.e.,provide consistent accuracy across configurations that differ from those used during *** order to realize the promise of ML-based potentials,systematic and scalable approaches to generate diverse training sets need to be *** work creates a diverse training set for tungsten in an automated manner using an entropy optimization ***,multiple polynomial and neural network potentials are trained on the entropy-optimized dataset.A corresponding set of potentials are trained on an expert-curated dataset for tungsten for *** models trained to the entropy-optimized data exhibited superior transferability compared to the expert-curated ***,the models trained to the expert-curated set exhibited a significant decrease in performance when evaluated on out-of-sample configurations.

关键词： entropy transfer configuration