bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implicit and coupled fluid plasma solver with adaptive Cartesian mesh and its applications to non-equilibrium gas discharges
Authors: Arslanbekov Robert R , Kolobov Vladimir I 
Published: March 2021

Abstract
We present a new fluid plasma solver with adaptive Cartesian mesh (ACM) based on a full-Newton (nonlinear, implicit) scheme for non-equilibrium gas discharge plasma. The electrons and ions are described using drift–diffusion approximation coupled to Poisson equation for the electric field. The electron-energy transport equation is solved to account for electron thermal conductivity, Joule heating, and energy loss of electrons in collisions with neutral species. The rate of electron-induced ionization is a function of electron temperature and could also depend on electron density (important for plasma stratification). The ion and gas temperature are kept constant. The transport equations are discretized using a non-isothermal Scharfetter–Gummel scheme to resolve possible large temperature gradients in the sheaths. We demonstrate the new solver for simulations of direct current (DC) and radiofrequency (RF) discharges. The implicit treatment of the coupled equations allows using large time steps. The full-Newton method (FNM) enables fast nonlinear convergence at each time step, offering significantly improved simulation efficiency. We discuss the selection of time steps for solving different plasma problems. The new solver enables solving several problems we could not solve before with existing software: two- and three-dimensional structures of the entire DC discharges including cathode and anode regions, electric field reversals and double-layer formation, the normal cathode spot and an anode ring, moving striations in diffuse and constricted DC discharges, and standing striations in RF discharges. The developed FNM-ACM technique offers many benefits for tackling the disparity of gas discharge plasma systems' time scales and nonlinearity.
Ultralow-power instant-on photon-pair counting and photon-entanglement analysis
Authors: Liu Xinghua , Fedotov Ilya V , Liu Jiru , Maleki Yusef , Vincent Christapher , Blakley Sean M , Zheltikov Aleksei M 
Published: March 2021

Abstract
The latest breakthroughs in quantum technologies, such as satellite quantum communications, present new challenges, imposing stringent restrictions on weight, size, and power consumption of quantum information systems. Here, we show that nonlinear and quantum optics provides powerful resources to confront these challenges by offering attractive solutions for photon-pair counting and quantum-entanglement detection. We demonstrate a low-cost, readily miniaturizable photon-pair counting module, which consumes less than 100 μAh during a sub-10 ms power-on/off measurement cycle, thus providing a meaningful performance as a promising component for satellite quantum technologies.
QCD phase diagram at finite isospin and baryon chemical potentials with the self-consistent mean field approximation *
Authors: Wu Zu-Qing , Ping Jia-Lun , Zong Hong-Shi 
Published: March 2021

Abstract
The self-consistent mean field approximation of the two-flavor NJL model, with a free parameter

to reflect the competition between the "direct" channel and the "exchange" channel, is employed to study the QCD phase structure at finite isospin chemical potential

, finite baryon chemical potential

and finite temperature T, and especially to study the location of the QCD critical point. Our results show that in order to match the corresponding lattice results of isospin density and energy density, the contributions of the "exchange" channel need to be considered in the framework of the NJL model, and a weighting factor

should be taken. It is also found that for fixed isospin chemical potentials, the lower temperature of the phase transition is obtained with increasing

in the

plane, and the largest difference of the phase transition temperature with different

's appears at

. At

the temperature of the QCD critical end point (CEP) decreases with increasing

, while the critical baryon chemical potential increases. At high isospin chemical potential (

MeV), the temperature of the QCD tricritical point (TCP) increases with increasing

, and in the low temperature regions the system will transition from the pion superfluidity phase to the normal phase as

increases. At low density, the critical temperature of the QCD phase transition with different

's rapidly increases with

at the beginning, and then increases smoothly around

MeV. In the high baryon density region, the increase of the isospin chemical potential will raise the critical baryon chemical potential of the phase transition.
Belief propagation guided decimation algorithms for random constraint satisfaction problems with growing domains
Authors: Zhao Chun-Yan , Fu Yan-Rong 
Published: March 2021

Abstract
We propose three kinds of belief propagation (BP) guided decimation algorithms using asynchronous updating strategy to solve a prototype of random constraint satisfaction problem with growing domains referred to as model RB. For model RB, the exact satisfiability phase transitions have been established rigorously, and almost all instances are intrinsic hard in the transition region. Finding solutions of a random instance of model RB is very challenging, and the problem size is limited to 102. The BP guided decimation algorithms we proposed are called asynchronous updating belief propagation (ABP) algorithm, asynchronous updating belief propagation* (ABP*) algorithm, and asynchronous updating belief propagation with variable order (VABP) algorithm, respectively. In the BP part of the algorithms, we adopt asynchronous updating strategy to obtain the latest passing messages between constraints and variables, which can improve the convergence of BP equations. We also use a damping factor that adds the old messages with a certain weight into the new messages sent from variables to constraints, to reduce the occurrence of oscillation during the convergence of BP equations. In the ABP algorithm, we compute the marginal probability distribution of all variables according to the messages obtained after the BP equations converge, then select the most biased variable and fix its value on the component with the maximum probability. While the ABP* algorithm considers how to continue the decimation process if the BP equations do not converge. Different from the previous two algorithms, in the VABP algorithm, we first choose a random order of the variables, and then assign values to the variables according to the given order after BP converges. Experimental results suggest that the three kinds of BP guided decimation algorithms appear to be very effective in solving random instances of model RB even when the constraint tightness is close to the theoretical satisfiability threshold. To evaluate the performance of the ABP algorithm, we also provide synchronous updating BP algorithms as a comparison. The entropy of the selected variable at each time step and the average freedom of the variables at different constraint tightness are also discussed. Besides, we analyze the convergence of BP equations and the influence of the order of the selected variables in the decimation process of the BP guided decimation algorithms.
Weak Guidance, Multi-index and Exact Mode Eigenvalue Calculation for Mode Intensity Profiles in Tapers
Authors: Ek-Ek J R , Martinez-Pinon F , Perez-Sanchez G G , Offerhaus H L , Alvarez-Chavez J A 
Published: March 2021

Abstract
The fundamental mode intensity profile is calculated for different points along the transition of an optical fibre taper from standard size (125 μm external cladding diameter and 8 μm core diameter) down to micro (1 μm external fibre diameter) and submicro size (down to 440 nm fibre diameter) at 1550 nm operational wavelength. The first section of the taper was evaluated using weak guidance approximation, the second section was treated as a three-index layer structure (double-clad) and evaluated with eigenvalue equations for three refractive indices. An external medium being a liquid with a refractive index close to silica is being considered. The third and thinnest section of the taper was evaluated with the exact mode eigenvalue equation. The results show that the fundamental mode intensity for the third section show a discontinuity just at the fibre edge with a peak amplitude larger than the optical field at the centre of the fibre. The taper shape that complies with the adiabaticity criterion and how the mode intensity profile and the spot size (Petermann 1 definition) of the fundamental mode change along their position on the taper were determined.
Construction of dual-axis sun tracker controlled by Arduino
Authors: Alvarez-Herrera C 
Published: March 2021

Abstract
In this work a dual-axis sun tracker was constructed using an Arduino to control two DC electric motors. The motors together with gears move a structure that tracks the sun. To achieve that purpose, an arrangement of four photoresistors was made to input the sun position into the Arduino in form of electric signal. The output signal from the Arduino is used in four relays with their respective optocouplers to transmit power into two DC electric motors to move the tracker. The Arduino uses an algorithm that processes the photoresistors signal and produce it an output signal that is transmitted to the relays. The sun tracker was applied in parabolic dish with good performance.
Thermal and Exergy Evaluation of a Parabolic Solar Cooker for Domestic use at Home
Authors: Terres H , Chávez S , Lizardi A , López R , Vaca M , Lara A , Morales J 
Published: March 2021

Abstract
The results of the thermal behavior and exergy efficiency of a prototype of a parabolic solar cooker are shown. The design and construction of the prototype consider aspects that have not been addressed in other devices of the same nature, such as easy construction and low cost. The results of the temperature reached approximately 96 ° C can be useful for use in domestic applications of cooking and heating food in homes. The evaluation of the efficiencies both first and second law show values less than 45% and 5% respectively and these generate the possibility of carrying out improvements in the solar cooker, which would allow significant improvements to be made in the times required for cooking. and food heating. If the construction-cost relationship of the device is considered, the analysis presented in this work can contribute to its promotion and use in the society that demands alternatives to current and future energy problems.
Energy and exergy analyses of a portable air conditioner system.
Authors: López R , Vaca M , Terres H , Lizardi A , Chávez S , Lara A 
Published: March 2021

Abstract
In this analysis the main objective is to evaluate the thermodynamic behavior of a portable air conditioning system. The power is 4,103 kW. To achieve this, the device was implemented with pre-calibrated thermocouples, taking care that there was always a proper contact with the pipes in order to minimize the differences between the measurement and the actual value. The ESS software and the coolant thermodynamic diagram were used to determine the value of the properties at the considered points. The refrigerant used by this device is the R 410A. Although the first law of thermodynamics can be used to assess the energy consumption, it makes no distinction between quantity and quality of energy. Energy analysis provides only the amount of supplied energy. Exergy analysis provides the maximum useful work that can be obtained by a system that is in balance with the environment. The COP (Coefficient of Performance), turned out to be 7.35, which is acceptable for this type of device. The exergetic efficiency was 4.17. Finally, the hot air flow coming from the condenser was 3.15 kW, this value is significant and will be used in some drying application.
Characterization of a pulsed rhodamine/ethanol dye laser
Authors: García-Villarreal A. , Robledo-Martinez A. , Espejo-Ramos H. , Sobral H. 
Published: March 2021

Abstract
We present here the implementation and characterization of a rhodamine dye laser pumped by a pulsed, high-power solid-state laser. The employed dye consisted of a solution of rhodamine 6G in ethanol at different concentrations. To maximize the laser efficiency the second harmonic of a pulsed Nd: YAG was used to collinearly pump the cavity. In particular, the effect of rhodamine concentration and pump energy on the laser emission were investigated. The laser emission obtained was found to have, on average, a width at half maximum (FWHM) of 12 nm. It was found, for example, that the wavelength of the output line varies linearly with the dye’s concentration. Under the employed experimental conditions, maximum efficiency of 12% is obtained with a concentration of 2.5×10−7 mol/l rhodamine in alcohol.
Lower Limb Design for a Child Test Dummy, based on Osteogenesis Imperfecta characteristics
Authors: Cuautle-Estrada A , Torres-SanMiguel C R , Rivera-Hernández M A , Ramírez O , Urriolagoitia-Calderón G M 
Published: March 2021

Abstract
Active and passive safety have played an essential role in solidifying ground transportation. However, safety-focused on children with some rare diseases is little attacked. This article shows the design of a diseased leg prototype into a crash test dummy Q3, the novelty of this work is based on the morphology and biocompatibility of the lower limbs, which principal characteristics of this prototype replicate the shape of a child with bone-degenerative diseases. In this work, it shows the essential features that a child dummy of this type must contain in order to generate a homologation and approval under the strictest passive safety standards used in the automotive industry. Results show the important kinematics parameters and CAD bones development necessary to conform a new numerical crash test dummy prototype.
Extraction of main elements from a TEM composite laser pattern
Authors: Zúñiga V Torres , Velázquez Aguilar V M , Bañuelos Muñeton J G 
Published: March 2021

Abstract
We examined the atypical formation and superposition of transverse electromagnetic modes (TEM) of high order in a commercial He-Ne laser (@543.5 nm). The competence of the dominant modes exhibits a periodic and stable dynamic, uncommon in industrialized systems. Also, the intensity shows a smooth transition. The origin of the phenomenon is only a product of intra-cavity diffractive components. We found the promotors are a stable optical cavity but quasi-degenerated, with large transversal section (the Fresnel number is irregular), and a breaking the axial symmetry (producing astigmatism). The analysis of the average intensity patterns, and a correlation algorithm — via bi-orthogonal decomposition based on Hermite-Gauss polynomials — expose the five principal TEM elements. These results could be meaningful and inspiring both in courses of optics, laser engineering as in image processing.
Magnetic and Electrical properties of Vitrovac/Au/Vitrovac multilayered obtained by means of magnetron sputtering
Authors: Pinzón-Escobar E F , Montiel H , García A Esparza , Alvarez G 
Published: March 2021

Abstract
We report the effect of the intermediate nonmagnetic layer and the influence of the thickness on the magnetic and electrical properties in Co-based amorphous multilayered, whose composition is VITROVAC-6030/Au/VITROVAC-6030; and these were deposited by DC magnetron sputtering technique. In all samples, the first VITROVAC-6030 layer was deposited on silica glasses substrate, with thickness from 30 to 125 nm, and the middle layer is Au with 5 nm thickness; in top, the VITROVAC-6030 layer was deposited with 30 nm thickness. Additionally, the photolithography process was employed to etch strip patterns on multilayered with length 1 cm and width between 0.1 mm to 1 mm; that it can induce magnetic anisotropy, therefore a change in easy magnetic axis. Finally, we have also made a comparison of magnetic and electrical properties between multilayered and strip patterns on multilayered; where the electrical resistance of multilayered depends on both VITROVAC and Au layer thickness, and electrical measurements show a conductive behavior with high resistance value.
Finding meaning in quadratic equations through a physical context: falling objects motion
Authors: Fallas-Soto R D , Orozco-del-Castillo M G , Perez-Oxté I , Hernández-Gómez J J , Yañez-Casas G A 
Published: March 2021

Abstract
This paper presents the results of the implementation of a design focused on the resignification of the parameters of the quadratic equation (parabolas) through the context of a physical phenomenon. This design was based on an epistemology of practices framed in principles of cognitive and social constructivism, particularly the socioepistemological theory of mathematics education, based also on the model of guided discovery. Based on the students’ arguments, evidence of resignification is shown in the parameters of the quadratic equation in such a way that relationships between algebraic and graphical expressions were established. It was identified that the students’ experiences, as well as the context, were determining elements for success in the resolution of the design.
Alternatives for improving the compressive strength of clay-based bricks
Authors: Jiménez-Quero V.G. , Guerrero-Paz J. , Ortiz-Guzmán M. 
Published: March 2021

Abstract
In this work three alternatives to improve the compressive strength of clay-based bricks were evaluated. Four mixtures were prepared: the control with only CLAY (without any treatment), one single mixture with the ground and screened clay (CLAYGS), one binary mixture in which CLAYGS was partially replaced by fly ash (FA) and one ternary mixture in which CLAYGS was partially replaced by FA plus Sugar Cane Bagasse Ash (SCBA). Apparent densities and porosities (ASTM C-20), initial rates of absorption (ASTM C-67) and compressive strengths (ASTM C-67) were determined. The results showed that the use of CLAYGS has positive effects on the density, porosity and compressive strength of bricks made with this material. Bricks made with CLAYGS were 23.08% denser, 20% less porous and 64.41% more resistant to compression than control bricks. According to the ASTM C-62 standard, the bricks obtained correspond to the MW grade. The partial replacement of CLAYGS with 20% FA improves the quality of bricks made only with CLAYGS and with CLAY. According to the ASTM C 62 standard, the bricks made with binary mixture (CLAYGS+FA) have the compressive strength required to be considered SW grade bricks. The addition of SCBA in binary bricks negatively affects their compressive strength.
Effect of the position of the internal reflectors on the thermal operation of a solar cooker box-type
Authors: Terres H , Chávez S , Lizardi A , Alvarez E 
Published: March 2021

Abstract
The results of the effect that five internal reflectors have on the operation of a box-type solar cooker are shown. Variations in the angular position of the reflectors generate new dimensions for the cooker. For this reason, in order to carry out the comparison of four solar cookers with different dimensions under the same operating conditions, it is used the numerical simulation that allows obtaining the representative temperatures that describe the thermal operation of the solar cooker. The temperature values achieved and expressly referred to the heating of 1 liter of water are obtained from the numerical solution of a mathematical model under initial conditions. The results show that for a tilt of the reflector angles with respect to the horizontal of 40°, 50°, 60°, 70° and 81° the highest values of the water temperature are obtained, specifically, the highest value among these is 98.1 ° C. While for reflector inclinations of 13°, 18°, 21°, 24° and 30°, there are the lowest temperature values and among these, the highest value is 83.9 °C. The results, together with their discussion, contribute to the knowledge of the behavior of the components of box-type solar cookers.
Data Mining applied to interventional cardiology procedures
Authors: Toledo M R , Vázquez E R , García-Salcedo R , Gómez-Vargas I , Uruchurtu E S , Rivera-Montalvo T 
Published: March 2021

Abstract
The diagnosis in the cardiological treatment is fundamental. Computational algorithms allow to analyse better the available medical data from a huge number of patients and use it to improve the diagnosis mechanism. In this work data from several patients of a Mexican cardiological Institute was recollected and prepossessed to analyse it with a data mining technique called clustering.
Optical properties of InAs quantum dots embedded in InGaAs/AlGaAs/GaAs structures with different capping layers
Authors: Cisneros-Tamayo R , Torchynska T , Casas-Espinola J L , Polupan G , Reséndiz-Chincoya M 
Published: March 2021

Abstract
The InAs quantum dots (QDs) embedded in Al0.30Ga0.70As/InGaAs/AlGaInAs/Al0.30Ga0.70As structures and covered by strain reduced AlGaInAs capping layer have been investigated in as grown state by means of a photoluminescence method. Three types of QD structures with different QD capping layers: GaAs (#1), Al0.10In0.15Ga0.75As (#2) and Al0.40In0.15Ga0.45As (#3) are compared. It is revealed that the QD emission in the structure with Al0.10In0.15Ga0.75As capping is characterized by the highest PL intensity of the ground state (GS) band and smaller the full with at half maximum (FWHM), compared to #1 and #3 structures. The variation of the GS emission peak versus temperature has been monitored within the range of 10-500K for the as grown film states and compared with shrinkage of the energy bandgaps in the InAs and GaAs bulk crystals. The results show that the efficiency of Ga/Al/In intermixing in #2 and #3 is less than in #1. Finally, the peculiarities of PL spectra of the studied QD structures have been analyzed and discussed.
Design of a method for the evaluation of natural and anthropic radionuclides in Chilean soils
Authors: Mera E , Correa R , Camacho E , Osorio R , Godoy S , Donoso S 
Published: March 2021

Abstract
The present work search to design a method for the evaluation of natural and anthropic radionuclides in Chilean soils, for which the international literature was reviewed, a hybrid method is generated product of the literature analysis and equipment availability in Chile, and is executed an example based on the recommended method.
Modeling of cloudiness based on the difference between the theoretical solar irradiance and the real solar irradiance on the earth’s surface for the installation of photovoltaic energy projects
Authors: Mera E , Pacheco P , Parodi C , Gutiérrez L 
Published: March 2021

Abstract
Considering that the solar irradiance on the surface is a direct indicator of cloudiness [1], we proceeded to make a model that determines the cloudiness, contrasting the differences that are generated between the theoretical solar irradiance estimated on the surface [1] [2] and real solar irradiance recorded on the surface. To evaluate the quality of the model, the real cloud values and the estimates were contrasted in a dispersion diagram, both in eighths at the daily average level, obtaining a correlation coefficient of 0.7. The modeling of cloudiness is a relevant variable for the installation of photovoltaic energy projects.