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Metal-modulated epitaxy of Mg-doped Al_(0.80)In_(0.20)N-based layer for application as the electron blocking layer in deep ultraviolet light-emitting diodes

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Journal of Semiconductors 2024年第5期45卷 80-89页

作者： horacio Irán Solís-Cisneros Carlos Alberto Hernández-Gutiérrez Enrique Campos-González Máximo López-López Optomechatronics Group Tecnológico Nacional de México Campus Tuxtla Gutiérrezcarretera Panamericana 1080C.P.29050Tuxtla GutiérrezChiapasMéxico Departamento de Física Instituto Nacional de Investigaciones NuclearesCarretera México-Toluca s/nC.P.52750La Marquesa OcoyoacacMéxico Departamento de Física Centro de Investigación y estudios Avanzados del Instituto Politécnico NacionalAv.Instituto Politécnico Nacional 2508San Pedro ZacatencoGustavo A.Madero07360 Ciudad de MéxicoCDMXMéxico

This work reports the growth and characterization of p-AlInN layers doped with Mg by plasma-assisted molecular beam epitaxy(PAMBE).AlInN was grown with an Al molar fraction of 0.80 by metal-modulated epitaxy(MME)with a thickness of 180 nm on Si(111)substrates using AlN as buffer *** substrate temperatures were used to enhance the incorporation of indium atoms into the alloy without clustering,as confirmed by X-ray diffraction(XRD).Cathodoluminescence measurements revealed ultraviolet(Uv)range ***,Hall effect measurements indicated a maximum hole mobility of 146 cm^(2)/(v∙s),corresponding to a free hole concentration of 1.23×10^(19)cm^(−3).The samples were analyzed by X-ray photoelectron spectroscopy(XPS)estimating the alloy composition and extracting the Fermi level by valence band ***-doped AlInN layers were studied for use as the electron-blocking layer(EBL)in LED *** varied the Al composition in the EBL from 0.84 to 0.96 molar fraction to assess its theoretical effects on electroluminescence,carrier concentration,and electric field,using SILvACO *** results from this study highlight the importance and capability of producing high-quality Mg-doped p-AlInN layers through *** simulations suggest that an Al content of 0.86 is optimal for achieving desired outcomes in electroluminescence,carrier concentration,and electric field.

关键词： metal-modulated epitaxy AlInN DUv-LED EBL simulation

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Numerical simulation of sedimentation processes in reservoirs as a function of outlet location

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International Journal of Sediment Research 2009年第3期24卷 339-351页

作者： horacio TONIOLO Civil and Environmental Engineering Department University of Alaska Fairbanks

This paper builds on a recently published one-dimensional moving-boundary model of the coevolution of topset, foreset and bottomset in a reservoir that captures the dynamics of the internal muddy pond typical to reservoirs. This model was modified to account for different outlet locations at the reservoir’s downstream end. This model considers a river carrying two sustained phases of sediments: coarse (sand) and fine (mud). The coarse phase deposits in the topset and delta foreset, while the fine phase forms a dilute suspension of wash load in the river. As the river enters the reservoir, the muddy water plunges on the foreset to form a Froude-supercritical (purely depositional) turbidity current. This turbidity current emplaces the bottomset. The modified numerical model was tested against five laboratory experiments previously reported by the author. The model successfully locates the muddy-water/clear-water interface. In addition, modeled and measured bed deposits are in good agreement. Results clearly indicate that the location of the internal hydraulic jump plays a key role in the final bed deposit.

关键词： Numerical model Delta Ponded turbidity currents Outlet location Reservoirs

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Piezoelectric constant temperature dependence in strained [111]-oriented zinc-blende MQW-SOAs

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Chinese Optics Letters 2023年第9期21卷 107-112页

作者： horacio Soto-Ortiz Gerson Torres-Miranda Applied Physics Division Center for Scientific Research and Higher Education of Ensenada

Here,we present a study of the effective piezoelectric constant(e_(14_(e)))temperature dependence in strained[111]-oriented zinc-blende quantum wells(QWs)embedded within a semiconductor optical amplifier(SOA).We determined e_(14_(e)) using a method that was insensitive to the segregation phenomenon and to the temperature dependence of the bandgap energy,which required neither fitting parameters nor temperature-dependent expressions for energy and out-of-plane effective masses of electrons and heavy *** e_(14_(e))=−0.0534±0.0040 C·m^(−2) at 23°C was obtained for an SOA with 1.2 nm[111]-oriented strained In0.687Ga0.313As/In0.807Ga0.193As0.304P0.696 *** previously published research,where e_(14_(e)) magnitude increased as temperature rised,we extracted an e_(14_(e)) magnitude that decreased as temperature increased.

关键词： piezoelectric constant pyroelectric effect quantum-confined Stark effect excitons semiconductor optical amplifiers zinc-blende quantum wells

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Machine learning assisted design of shape-programmable 3D kirigami metamaterials

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npj Computational Materials 2022年第1期8卷 1817-1828页

作者： Nicolas A.Alderete Nibir Pathak horacio D.Espinosa Theoretical and Applied Mechanics Northwestern UniversityEvanstonIL60208USA Department of Mechanical Engineering Northwestern UniversityEvanstonIL60208USA

Kirigami-engineering has become an avenue for realizing multifunctional metamaterials that tap into the instability landscape of planar surfaces embedded with ***,it has been shown that two-dimensional Kirigami motifs can unfurl a rich space of out-of-plane deformations,which are programmable and controllable across spatial *** Kirigami’s versatility,arriving at a cut layout that yields the desired functionality remains a ***,we introduce a comprehensive machine learning framework to shed light on the Kirigami design space and to rationally guide the design and control of Kirigami-based materials from the meta-atom to the metamaterial *** employ a combination of clustering,tandem neural networks,and symbolic regression analyses to obtain Kirigami that fulfills specific design constraints and inform on their control and *** systematic approach is experimentally demonstrated by examining a variety of applications at different hierarchical levels,effectively providing a tool for the discovery of shape-shifting Kirigami metamaterials.

关键词： shape hierarchical shifting

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DISCUSSION ON “NUMERICAL SIMULATION OF SEDIMENT RELEASE FROM RESERvOIRS” (No. 1,2006) BY KHOSROWNEJAD A. AND NEISHABORI A.

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International Journal of Sediment Research 2007年第1期22卷 80-86页

作者： horacio TONIOLO Alfredo TRENTO Civil and Environmental Engineering Department University of Alaska Fairbanks Facultad de Ingenieria y Ciencias Hidricas Universidad Nacional del Litoral

Sedimentation processes in reservoirs can be studied by performing theoretical analysis, laboratory experimentation, numerical simulation, or a combination of these three methods. Available literature focused on reservoirs is abundant. For instance, the works conducted by Hotchkiss and Parker (1991), Morris and Fan (1997), and De Cesare et al.

关键词： AND NEISHABORI A BY KHOSROWNEJAD A DISCUSSION ON NUMERICAL SIMULATION OF SEDIMENT RELEASE FROM RESERvOIRS No

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Nonlinear robust H-infinity filtering for a class of uncertain systems via convex optimization

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控制理论与应用（英文版） 2012年第2期10卷 152-158页

作者： Masoud ABBASZADEH horacio J. MARQUEZ United Technologies Research Center East HartfordCT 06108U.S.A. Department of Electrical and Computer Engineering University of AlbertaEdmontonAlbertaCanada T6G 2V4

A new approach for robust H-infinity filtering for a class of Lipschitz nonlinear systems with time-varying uncertainties both in the linear and nonlinear parts of the system is proposed in an LMI framework. The admissible Lipschitz constant of the system and the disturbance attenuation level are maximized simultaneously through convex multi-objective optimization. The resulting H-infinity filter guarantees asymptotic stability of the estimation error dynamics with exponential convergence and is robust against nonlinear additive uncertainty and time-varying parametric uncertainties. Explicit bounds on the nonlinear uncertainty are derived based on norm-wise and element-wise robustness analysis.

关键词： Nonlinear uncertain systems Robust observers Nonlinear H-infinity filtering Convex optimization

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Biomass and dominance of conservative species drive above-ground biomass productivity in a mediterranean-type forest of Chile

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Forest Ecosystems 2019年第4期6卷 339-351页

作者： Ariel Isaías Ayma-Romay horacio E.Bown Facultad de Ciencias Forestales y Conservación de la Naturaleza Universidad de Chile

Background: Forest productivity has a pivotal role in human well-being. vegetation quantity, niche complementarity, mass-ratio, and soil resources are alternative/complementary ecological mechanisms driving productivity. One challenge in current forest management depends on identifying and manipulating these mechanisms to enhance productivity. This study assessed the extent to which these mechanisms control aboveground biomass productivity(AGBP) of a Chilean mediterranean-type matorral. AGBP measured as tree aboveground biomass changes over a 7-years period, was estimated for twelve 25 m × 25 m plots across a wide range of matorral compositions and structures. variables related to canopy structure, species and functional diversity, species and functional dominance, soil texture, soil water and soil nitrogen content were measured as surrogates of the four mechanisms proposed. Linear regression models were used to test the hypotheses. A multimodel inference based on the Akaike’s information criterion was used to select the best models explaining AGBP and for identifying the relative importance of each ***: vegetation quantity(tree density) and mass-ratio(relative biomass of Cryptocarya alba, a conservative species) were the strongest drivers increasing AGBP, while niche complementarity(richness species) and soil resources(sand, %) had a smaller effect either decreasing or increasing AGBP, respectively. This study provides the first assessment of alternative mechanisms driving AGBP in mediterranean forests of Chile. There is strong evidence suggesting that the vegetation quantity and mass-ratio mechanisms are key drivers of AGBP, such as in other tropical and temperate forests. However, in contrast with other studies from mediterranean-type forests, our results show a negative effect of species diversity and a small effect of soil resources on ***: AGBP in the Chilean matorral depends mainly on the vegetation quantity and mass-ratio mechanisms

关键词： Above-ground biomass productivity Diversity Niche complementarity Mass-ratio Mediterranean Soil resources

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In Situ Tests of Multiwalled Carbon Nanotubes with Strength Close to Theoretical Predictions

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Chinese Physics Letters 2009年第1期26卷 194-197页

作者：彭倍 horacio D. Espinosa Center for Micro and Nano Electromechanical Systems University of Electronic Science and Technology of China Chengdu 610054 Micro and Nano Mechanics Laboratory Northwestern University Illinois 60208 USA

Using MEMS technology and transmission electron microscopy we show experimentally multiwalled carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceeds the earlier observations by a factor of approximately 3. These results are in excellent agreement with quantum-mechanical estimations. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging is used to directly determine the number of fractured shells and the ehirality of the outer shell. Electron irradiation at 200kev for 10, 100 and 1800s lead to improvements of the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. This procedure is a cost effective way of customizing the properties of multiwall nanotubes for many applications of interest ranging from nanocomposites to nanodevices.

关键词： field emission molybdenum dioxide enhancement factor

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Cerium,manganese and cerium/manganese ceramic monolithic *** of vOCs and PM removal

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Journal of Rare Earths 2016年第7期34卷 675-682页

作者： COLMAN-LERNER Esteban PELUSO Miguel Andres SAMBETH Jorge THOMAS horacio Centro de Investigacion y Desarrollo en Ciencias Aplicadas"Dr.Jorge J.Ronco"CONICET CCT La Plata UNLP47 N0 257(1900)La PlataArgentina Fac.de Ciencias Exactas UNLP47 and 115(1900)La PlataArgentina Centro de Investigaciones del Medio Ambiente(CIMA).Facultad de Ciencias Exactas UNLP.47y 115.1900-La Plata Planta Piloto Multiproposito PLAPIMU CICPBA-UNLPC.Centenario and 506M ***Argentina

Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aq precursor, and characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Brunauer-Emmett-Teller rn （BET）, temperature programmed reduction （Ha-TPR）, X-ray photoelectron spectroscopy （XPS） acidity measurements and elec conductivity. The catalytic activity was evaluated for volatile organic compounds （vOC）（ethanol, methyl ethyl ketone and tol oxidation. Additionally, catalysts were tested in particulate matter （PM） combustion. The characterization results indicated that Ce was in the form of Ce4＋ and Ce3＋, and Mn existed in the form of Mn4＋ and Mn3＋ on the surface of the Mn/AC sample and in the of Mn4＋ in the Ce/Mn/AC monolith. vOC oxidation results revealed that the Ce/Mn/AC sample showed an excellent perforr compared with ceramic supported CeO2 （Ce/AC） and MnO, （Mn/AC） samples. The PM combustion was also higher on Ce/M monoliths. The enhanced catalytic activity was mainly attributed to the Ce and Mn interaction which enhanced the acidity, cond ity and the reducibility of the oxides.

关键词： monolith vOCs MnOx Ce PM clays rare earths

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Hydrogen evolution kinetics on Ni cathodes modified by spontaneous deposition of Ag or Cu

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Journal of Energy Chemistry 2017年第3期26卷 466-475页

作者： Esteban A.Franceschini Gabriela I.Lacconi horacio R.Corti INFIQC-CONICET Departamento de Fisicoquímica–Facultad de Ciencias QuímicasUniversidad Nacional de CórdobaCiudad Universitaria5000 CórdobaArgentina Departamento de Física de la Materia Condensada Centro Atómico ConstituyentesComisión Nacional de Energía AtómicaAv.Gral.Paz 1499(B1650KNA)San MartínBuenos AiresArgentina INQUIMAE-CONICET Facultad de Ciencias Exactas y NaturalesUniversidad de Buenos AiresCiudad UniversitariaPabellón IIC1428EHABuenos AiresArgentina

Nickel modification by spontaneous deposition of transition metals such as Ag and Cu is shown as an economic and simple alternative for the activation of hydrogen evolution reaction（HER） on cathodes in alkaline media. The kinetics of HER is studied on Ni/Ag and Ni/Cu catalysts by cyclic voltammetry and electrochemical impedance spectroscopy（EIS） using a rotating disk electrode（RDE）. Freshly synthesized catalysts, as well as catalysts subjected to a short chronoamperometric ageing procedure, are analyzed and the kinetic and thermodynamic parameters of the HER are obtained. The nickel surface modified with transition metals with an outer shell electronic configuration [xd;（x+1）s;], such as Cu(3d;4s;)and Ag(4d;5s;), shows an improved activity for the HER compared to bare nickel. Furthermore, the Ni/Cu catalyst presents a decreased onset potential. The hydrogen evolution rate, measured as current density at –1.5 v（vs. SCE）, is similar on Ni/Cu and Ni/Ag electrodes.

关键词： Hydrogen evolution reaction Spontaneous deposition Nickel/Silver Nickel/Copper Electrochemical impedance spectroscopy

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