bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro hole drilling of high frequency printed circuit board containing hard fillers
Authors: Shi Hongyan , Liu Xianwen , Gao Zhisen , Huang Guang , Tao Sha , Fu Lianyu , Liang Xiong
Published: March 2021

High frequency printed circuit board (PCB), as the significant support for 5G technology, has been receiving intense attention from the increasing number of scholars. Concerning precision fabrication of high frequency PCBs, micro hole drilling is deemed as one of the extremely crucial challenges. In this study, the coated drill bits’ wear and micro hole quality were investigated through the drilling experiments of high frequency PCBs. Results showed that two kinds of coated drill bits exhibited well in terms of hole registration accuracy. Using diamond like carbon coated drill bits could obtain fewer burrs than drilled with diamond coated drill bits before drilling 200 holes, but the burr height increased very slowly with the increment of hole number when using diamond coated drill bits. Taking the combination of aluminum sheet and phenolic aldehyde board as the entry board was conducive to obtaining less burr, and the micro drill bits with helix angles of 40° and 42° were contributed to achieving less burr too. Additionally, decreasing the feed rate could lessen the hole blocking.
Pentagonal B2N3-based 3D metallic boron nitride with high energy density
Authors: Shen Yiheng , Xie Huanhuan , Wang Qian
Published: March 2021

Different from conventional insulating or semiconducting boron nitride, metallic BN has received increasing attention in recent years as its intrinsic metallicity grants it great potential for broad applications. In this study, by assembling the experimentally synthesized pentagonal B2N3 units, we have proposed the first pentagon-based three-dimensional (3D) metallic boron nitride, labeled penta-B4N7. First-principles calculations together with molecular dynamics simulations and convex hull diagram show that penta-B4N7 is not only thermally, dynamically and mechanically stable, but also three dimensionally metallic. A detailed analysis of its electronic structure reveals that the intrinsic metallicity comes from the delocalized electrons in the partially occupied antibonding N–N π orbitals. Equally important, the energy density of penta-B4N7 is found to be 4.07 kJ g−1, which is the highest among that of all the 3D boron nitrides reported so far.
Model reduction techniques for quantitative nano-mechanical AFM mode
Authors: Chang X , Hallais S , Roux S , Danas K
Published: March 2021

A recently developed atomic force microscope process, the PeakForce quantitative nanomechanical mapping (PF-QNM) mode, allows us to probe over a large spatial region surface topography together with a variety of mechanical properties (e.g. apparent modulus, adhesion, viscosity). The resulting large set of data often exhibits strong coupling between material response and surface topography. This letter proposes the use of a proper orthogonal decomposition (POD) technique to analyze and segment the force-indentation data obtained by the PF-QNM mode in a highly efficient and robust manner. Two examples illustrate the proposed methodology. In the first one, low-density polyethylene nanopods are deposited on a polystyrene film. The second is made of carbonyl iron particles embedded in a polydimethylsiloxane matrix. The proposed POD method permits us to seamlessly identify the underlying phase constituents in both samples and decouple them from the surface topography by compressing voluminous force-indentation data into a subset with a much lower dimensionality.
Two-dimensional talc as a van der Waals material for solid lubrication at the nanoscale
Authors: Vasić Borislav , Czibula Caterina , Kratzer Markus , R A Neves Bernardo , Matković Aleksandar , Teichert Christian
Published: March 2021

Talc is a van der Waals and naturally abundant mineral with the chemical formula Mg3Si4O10(OH)2. Two-dimensional (2D) talc could be an alternative to hBN as van der Waals dielectric in 2D heterostructures. Furthermore, due to its good mechanical and frictional properties, 2D talc could be integrated into various hybrid microelectromechanical systems, or used as a functional filler in polymers. However, properties of talcas one of the main representatives of the phyllosilicate (sheet silicates) group are almost completely unexplored when ultrathin crystalline films and monolayers are considered. We investigate 2D talc flakes down to single layer thickness and reveal their efficiency for solid lubrication at the nanoscale. We demonstrate by atomic force microscopy based methods and contact angle measurements that several nanometer thick talc flakes have all properties necessary for efficient lubrication: a low adhesion, hydrophobic nature, and a low friction coefficient of 0.10 ± 0.02. Compared to the silicon-dioxide substrate, 2D talc flakes reduce friction by more than a factor of five, adhesion by around 20%, and energy dissipation by around 7%. Considering our findings, together with the natural abundance of talc, we put forward that 2D talc can be a cost-effective solid lubricant in micro- and nano-mechanical devices.
Porous and hydrophobic graphene-based core–shell sponges for efficient removal of water contaminants
Authors: Wu Shiting , Xing Zhihao , Yuan Yongjun , Bai Wangfeng , Bao Liang , Pei Lang , Zhang Huaiwei
Published: March 2021

Water pollution is a global environmental problem that has attracted great concern, and functional carbon nanomaterials are widely used in water treatment. Here, to optimize the removal performance of both oil/organic matter and dye molecules, we fabricated porous and hydrophobic core–shell sponges by growing graphene on three-dimensional stacked copper nanowires. The interconnected pores between the one-dimensional nanocore–shells construct the porous channels within the sponge, and the multilayered graphene shells equip the sponge with a water contact angle over 120° even under acidic and alkaline environments, which enables fast and efficient cleanup of oil on or under the water. The core–shell sponge can absorb oil or organic solvents with densities 40–90 times its own, and its oil-sorption capacity is much larger than those of other porous materials like activated carbon and loofah. On the other hand, the adsorption behavior of the core–shell sponge to dyes including methyl orange (MO) and malachite green (MG), also common water pollutants, was also measured. Dynamic adsorption of MG under cyclic compression demonstrated a higher adsorption rate than that in the static state, and an acidic environment was favorable for the adsorption of MO molecules. Finally, the adsorption isotherm for MO molecules was analyzed and fitted with the Langmuir model, and the adsorption kinetics were studied in depth as well.
Time-dependent expansion of a weakly-collisional plasma beam in a paraxial magnetic nozzle
Authors: Zhou J , Sánchez-Arriaga G , Ahedo E
Published: March 2021

The transient and steady-state expansion of a weakly-collisional plasma beam in a paraxial magnetic nozzle is studied with a kinetic Boltzmann–Poisson model. Only intraspecies collisions involving electrons are considered and these are modeled with a Bhatnagar–Gross–Krook operator. Simulations show that occasional collisions progressively populate the phase-space region of isolated trapped electrons until a steady state is reached, which is independent of transient history. The steady state is characterized by a partial occupancy of that region increasing with the collisionality rate but far away from the full occupancy postulated by an alternative steady-state kinetic model. The changes on the amount of trapped electrons with the collisionality rate explain, in turn, the changes on the spatial profiles of main plasma magnitudes. Conclusions on the momentum and energy balances of ions and electrons agree, in terms of general trends, with those of the steady-state kinetic model. In the downstream region of the expansion, ions and electrons lose all their perpendicular energy but they still keep part of their parallel thermal energy. Electron heat fluxes of parallel energy are not negligible and are approximately proportional to enthalpy fluxes.
An improved conversion of the microwave energy into plasma in an optimized microwave plasma sheet source at 2.45 GHz designed for surface treatment
Authors: Miotk Robert , Jasiński Mariusz , Mizeraczyk Jerzy
Published: March 2021

Efficient conversion of the microwave energy into an atmospheric-pressure argon plasma in a microwave plasma sheet source (MPSS) operating at 2.45 GHz in ambient air is the subject of this work. The MPSSs, capable of providing an atmospheric pressure plasma in the shape of a narrow sheet are an innovative technology for variety of surface treatments with no impact on the environment. The existing designs of the MPSS exhibit unsatisfactory efficiency of the conversion of microwave energy produced by the microwave source into the microwave plasma (about 80%), which hinders implementation of the MPSSs in the industry. In this paper, after an analytical approach based on the equivalent electrical circuit method we proposed an optimization of the design of MPSS in terms of the microwave energy conversion efficiency. The MPSS design improvement consisted in reducing the electrical impedance in the input plane of the MPSS by introducing a capacitive diaphragm into the MPSS transmission line, which compensated the inductive character of the plasma sheet. The experimental measurement of the electrodynamic characteristics of the MPSS with diaphragm showed that using the diaphragm significantly decreased the microwave power losses due to the microwave reflection from about (20–30)% to a level of several percent. This substantially increased the MPSS energy conversion efficiency up to about 97%, 93% and 87% for incident powers P
I of 500 W, 750 W and 1000 W, respectively. The electrodynamic characteristics of the MPSS appeared a very convenient tool for determining the conditions of maximum efficiency of conversion of the microwave energy into the microwave plasma. The electrodynamic characteristics were measured at argon flow rate of 20 Nl min−1. The analysis of the calculated input impedances of the MPSSs with and without diaphragm, based on the equivalent electrical circuits of both MPSSs confirmed that the change of the character of the input reactance of the MPSS from inductive to capacitive after introducing the diaphragm is the cause of the increase in the MPSS energy conversion efficiency. The MPSSs having the energy conversion efficiency such high as presented in this paper appears to be attractive innovative technology for economic use in industrial applications.
Optimal system, symmetry reductions and group-invariant solutions of (2+1)-dimensional ZK-BBM equation
Authors: Tanwar Dig Vijay
Published: March 2021

The present article intends to generate optimal system of one dimensional subalgebra and group–invariant solutions of ZK–BBM equation with the aid of Lie group theory. The ZK–BBM equation is long wave equation with large wavelength, which describes the water wave phenomena in nonlinear dispersive system. The infinitesimal vectors, commutative relations and invariant functions for optimal system of ZK–BBM equation are derived under invariance of Lie groups. The invariance property leads to the reduction of independent variable and leaves the system invariant. Based on the optimal system, ZK–BBM equation is transformed into ordinary differential equations by twice reductions. These ODEs are solved under parametric constraints and result into invariant solutions. The obtained solutions are analyzed physically based on their numerical simulation. Consequently, elastic multisoliton, dark and bright lumps, compacton and annihilation profiles of the solutions are well presented graphically.
The Lyman Alpha Spectral Database (LASD)
Authors: Runnholm Axel , Gronke Max , Hayes Matthew
Published: March 2021

Lymanα (Lyα) emission from star-forming galaxies is an important tool to study a large range of astrophysical questions: it has the potential to carry information about the source galaxy, its nearby circumgalactic medium, and also the surrounding intergalactic medium. Substantial observational and theoretical work has therefore focused on understanding the details of this emission line. These efforts have been hampered, however, by an absence of spectroscopic reference samples that can be used both as comparisons for observational studies and as critical tests for theoretical work. For this reason, we have compiled a large sample of Lyα spectra, at both low and high redshift, and created a publicly available online database, at lasd.lyman-alpha.com. The Lyman Alpha Spectral Database (LASD) hosts these spectra, as well as a large set of spectral and kinematic quantities that have been homogeneously measured for the entire sample. As part of this we have developed an automated redshift determination algorithm which we show is accurate to within less than ±180 kms−1 on average, across many different Lyα profiles. The measurements can conveniently be viewed online and downloaded in tabular form. The LASD has the capacity for users to easily upload their own Lyα spectra, and all the same spectral measurements will be made, reported, and ingested into the database. We actively invite the community to do so, and the LASD is intended to be a long-term community resource. In this paper we present the design of the database as well as descriptions of the underlying algorithms and the initial Lyα emitter samples that are in the database.
Controllable Goos–Hänchen shift and optical switching in an Er3 + -doped yttrium aluminum garnet crystal
Authors: Chen Xiu-Mei , Shui Tao , Meng Chun , Zhang Tong , Deng Xu , Yang Wen-Xing
Published: March 2021

We propose an efficient scheme to control Goos–Hänchen (GH) shifts of the reflected and transmitted beams in a cavity containing Er3 + -doped yttrium-aluminum-garnet (YAG) crystal with a four-level Er3 +  ionic system. It is found that both the values and signs of the reflected and transmitted GH shifts can be coherently controlled by tuning the relevant optical parameters, such as the incoherent pumping rate, and the intensity and detuning of the driving field. Furthermore, we propose a scheme for such a configuration of the reflected GH shift as a family of reflection-type optical switchings. It is shown that the average port spacing and reflectivity of the optical switching can reach approximately 1.03 mm and 16.88, respectively, which indicate the high performance of switching function. Our proposal may provide a possibility to implement optically tuned optical switching.
Novel rubidium polyfluorides with F3, F4, and F5 species*
Authors: Lin Ziyue , Yu Hongyu , Song Hao , Zhang Zihan , Liang Tianxiao , Du Mingyang , Duan Defang
Published: March 2021

Pressure has an important effect on chemical bonds and their chemical properties. The atypical compounds NaCl3 and CsF3 are predicted to be stable at high pressure and show unique physical and chemical properties. By using ab initio random structure searching and density functional theory calculations, we predicted multiple thermodynamically stable atypical compounds, which are RbF2, RbF3, RbF4, and RbF5 in the pressure range of 0–300 GPa. In these stable compounds, homonuclear bondings of F3, F4, and F5 species are easily formed. The electron structure calculation showed that except for Fd-3m phase of RbF2, these stable compounds are insulators and F 5p orbitals play an important role in the Fermi level. It is interesting that the compounds RbF5 could be stable at nearly ambient pressure and 0 K which will stimulate experimental studies in the future.
ASH: an Automatic pipeline to generate realistic and individualized chronic Stroke volume conduction Head models
Authors: Carla Piastra Maria , van der Cruijsen Joris , Piai Vitória , Jeukens Floor E M , Manoochehri Mana , Schouten Alfred C , Selles Ruud W , Oostendorp Thom
Published: March 2021

Objective. Large structural brain changes, such as chronic stroke lesions, alter the current pathways throughout the patients’ head and therefore have to be taken into account when performing transcranial direct current stimulation simulations. Approach. We implement, test and distribute the first MATLAB pipeline that automatically generates realistic and individualized volume conduction head models of chronic stroke patients, by combining the already existing software SimNIBS, for the mesh generation, and lesion identification with neighborhood data analysis, for the lesion identification. To highlight the impact of our pipeline, we investigated the sensitivity of the electric field distribution to the lesion location and lesion conductivity in 16 stroke patients’ datasets. Main results. Our pipeline automatically generates 1 mm-resolution tetrahedral meshes including the lesion compartment in less than three hours. Moreover, for large lesions, we found a high sensitivity of the electric field distribution to the lesion conductivity value and location. Significance. This work facilitates optimizing electrode configurations with the goal to obtain more focal brain stimulations of the target volumes in rehabilitation for chronic stroke patients.
Hybrid asynchronous brain–computer interface for yes/no communication in patients with disorders of consciousness
Authors: Huang Jianyong , Qiu Lina , Lin Qianmin , Xiao Jun , Huang Yuanqiu , Huang Haiyun , Zhou Xinjie , Shi Xiangyu , Wang Fei , He Yanbin , Pan Jiahui
Published: March 2021

Objective. For patients with disorders of consciousness (DOC), such as vegetative state (VS) and minimally conscious state (MCS), communication is challenging. Currently, the communication methods of DOC patients are limited to behavioral responses. However, patients with DOC cannot provide sufficient behavioral responses due to motor impairments and limited attention. In this study, we proposed a hybrid asynchronous brain–computer interface (BCI) system that provides a new communication channel for patients with DOC. Approach. Seven patients with DOC (3 VS and 4 MCS) and eleven healthy subjects participated in our experiment. Each subject was instructed to focus on the square with the Chinese words ‘Yes’ and ‘No’. Then, the BCI system determined the target square with both P300 and steady-state visual evoked potential (SSVEP) detections. For the healthy group, we tested the performance of the hybrid system and the single-modality BCI system. Main results. All healthy subjects achieved significant accuracy (ranging from 72% to 100%) in both the hybrid system and the single modality system. The hybrid asynchronous BCI system outperformed the P300-only and SSVEP-only systems. Furthermore, we employed the asynchronous approach to dynamically collect the electroencephalography signal. Compared with the synchronous system, there was a 21% reduction in the average required rounds and a reduction of 105 s in the online experiment time. This asynchronous system was applied to detect the ‘yes/no’ communication function of seven patients with DOC, and the results showed that three of the patients (3 MCS) not only showed significant accuracies (67 ± 3%) in the online experiment, and their Coma Recovery Scale-Revised scores were also improved compared with the scores before the experiment. This result demonstrated that 3 of 7 patients were able to communicate using our hybrid asynchronous BCI system. Significance. This hybrid asynchronous BCI system can be used as a useful auxiliary bedside tool for simple communication with DOC patients.
Optimizing thermal block length during infrared neural inhibition to minimize temperature thresholds
Authors: Ford Jeremy B , Ganguly Mohit , Zhuo Junqi , McPheeters Matthew T , Jenkins Michael W , Chiel Hillel J , Jansen E Duco
Published: March 2021

Objective. Infrared neural inhibition (INI) is a method of blocking the generation or propagation of neural action potentials through laser heating with wavelengths strongly absorbed by water. Recent work has identified that the distance heated along axons, the block length (BL), modulates the temperature needed for inhibition; however, this relationship has not been characterized. This study explores how BL during INI can be optimized towards minimizing its temperature threshold. Approach. To understand the relationship between BL and the temperature required for INI, excised nerves from Aplysia californica were laser-heated over different lengths of axon during electrical stimulation of compound action potentials. INI was provided by irradiation (λ = 1470 nm) from a custom probe (n = 6 nerves), and subsequent validation was performed by providing heat block using perfused hot media over nerves (n = 5 nerves). Main Results. Two BL regimes were identified. Short BLs (thermal full width at half maximum (tFWHM) = 0.81–1.13 mm) demonstrated that increasing the tFWHM resulted in lower temperature thresholds for INI (p < 0.0125), while longer BLs (tFWHM = 1.13–3.03 mm) showed no significant change between the temperature threshold and tFWHM (p > 0.0125). Validation of this longer regime was performed using perfused hot media over different lengths of nerves. This secondary heating method similarly showed no significant change (p > 0.025) in the temperature threshold (tFWHM = 1.25–4.42 mm). Significance. This work characterized how the temperature threshold for neural heat block varies with BL and identified an optimal BL around tFWHM = 1.13 mm which minimizes both the maximum temperature applied to tissue and the volume of tissue heated during INI. Understanding how to optimally target lengths of nerve to minimize temperature during INI can help inform the design of devices for longitudinal animal studies and human implementation.
Critical points in the RP

N−1 model
Authors: Diouane Youness , Lamsen Noel , Delfino Gesualdo
Published: March 2021

The space of solutions of the exact renormalization group fixed point equations of the two-dimensional RP

N−1 model, which we recently obtained within the scale invariant scattering framework, is explored for continuous values of N ⩾ 0. Quasi-long-range order occurs only for N = 2, and allows for several lines of fixed points meeting at the Berezinskii–Kosterlitz–Thouless transition point. A rich pattern of fixed points is present below N* = 2.244 21‥, while only zero temperature criticality in the O(N(N + 1)/2 − 1) universality class can occur above this value. The interpretation of an extra solution at N = 3 requires the identification of a path to criticality specific to this value of N.
Probability density of fractional Brownian motion and the fractional Langevin equation with absorbing walls
Authors: Vojta Thomas , Warhover Alex
Published: March 2021

Fractional Brownian motion and the fractional Langevin equation are models of anomalous diffusion processes characterized by long-range power-law correlations in time. We employ large-scale computer simulations to study these models in two geometries, (i) the spreading of particles on a semi-infinite domain with an absorbing wall at one end and (ii) the stationary state on a finite interval with absorbing boundaries at both ends and a source in the center. We demonstrate that the probability density and other properties of the fractional Langevin equation can be mapped onto the corresponding quantities of fractional Brownian motion driven by the same noise if the anomalous diffusion exponent α is replaced by 2 − α. In contrast, the properties of fractional Brownian motion and the fractional Langevin equation with reflecting boundaries were recently shown to differ from each other qualitatively. Specifically, we find that the probability density close to an absorbing wall behaves as P(x) ∼ x

κ
with the distance x from the wall in the long-time limit. In the case of fractional Brownian motion, κ varies with the anomalous diffusion exponent α as κ = 2/α − 1, as was conjectured previously. We also compare our simulation results to a perturbative analytical approach to fractional Brownian motion.
Mechanical properties improvement in an advanced automotive steel
Authors: Duran-Núñez A , Aburto-Perdomo E , Hernandez-Garcia P , Ramírez-Ledesma A L , Juárez-Islas J A
Published: March 2021

Due to the increase in environmental and safety regulations that have been applied worldwide, the automotive industry has seen the need to develop steel alloys whose mechanical properties perform, not only reliably, but at a low cost. This is why the study of the third – generation steel has taken a defining position in the industry; due to the high mechanical properties, it offers and the advantages that will be reflected in the production of vehicles. In this sense, this study proposes an alternative to traditional materials, which not only reduces costs but also meets the characteristics required by the market based on two different processing routes: 1) hot – rolling + water quenching (HR + WQ), and 2)hot – rolling + water quenching + sub-zero treatment (HR + WQ + ST).
Irreversibility and First and Second Law Efficiencies Analysis in three different Solar Cookers Box-Type
Authors: Terres H , Chávez S , Lizardi A , López R , Vaca M , Lara A , Morales J
Published: March 2021

This work shows the results and evaluation of three box-type solar cookers. The cooker designs are octagonal, rectangular and square. Irreversibility, first and second law results are obtained considering the water heating process. These values indicate that the rectangular design has the highest efficiency values, although it does not have the highest temperature values. It is shown how the area of the glass cover of the cookers influences its efficiency since the increase in this value is not reflected in an improvement in efficiency. The effect of irreversibility and its impact over the second-law efficiency when the water heating process increases in the solar cookers are explained. The results are very useful because they allow us to assess the potential ranges of exergy when it is applied to energy devices such as solar cookers, which can contribute to the design and improvement of solar devices with the same characteristics.
Mechano-optical analysis of piezoelectric hydroxyapatite composites
Authors: Islas-García E , Torres-San Miguel C , García-Merino J
Published: March 2021

The piezoelectric behavior of Hydroxyapatite (HAp) composites by the mechanical action of high optical irradiances was studied. The piezoelectric and optical properties of HAp composites were considered based on previous researches. Using a finite method element and computational software, is obtained a numerical approximation of mechanical deformation by using a direct current voltage as input. It was considered a mechano-optical model to reproduce a normal force acting on the surface of the HAp composites provided by a nanosecond pulsed laser irradiation. The generated voltage was estimated under high optical irradiance using a proposed mathematical approach. This study can assist in the characterization of piezoelectric crystals by noninvasive disturbances. These results exposed the possibility of developing novel measurement procedures that involve nonlinear optical processes.
Energetic, Exergetic and Entropy Evaluation in the Solar Distillation
Authors: Chávez S , Terres H , Lizardi A , López R , Lara A , Vaca M
Published: March 2021

This work shows the evaluation of energy, exergy and entropy for the process of solar distillation of river water. The solar still is of the slope with fins and is tested for 3 initial volumes: 2, 4 and 6 L, for which data of temperature and solar radiation are recorded. Subsequently, the Dunkle’s thermal model is applied and the energy, exergy and entropy balance are established to determine the efficiencies. The results show that the maximum energy efficiency in the solar still for 2, 4 and 6 L is 45%, 36% and 30% respectively, in exergy efficiency its maximum values are 4.7%, 3.8% and 2.9% for 2, 4 and 6 L of river water and finally the analysis of the entropy change, reached the maximum value of 1 kJ/Kg K in the 3 experimental tests.
A device inspired by the mantis shrimp’s strike to produce cavitation bubbles on solid surfaces
Authors: Godínez F A , Guzmán J E V , Valdés R , Chávez O , De La Rosa K G , Cruz S
Published: March 2021

We discuss a low-cost mechanical device designed to generate cavitation bubbles through the impact of rigid surfaces. The process is triggered by a pivoting limb, which develops speeds as high as 180 rad/s (9 m/s) while submerged in water. A mathematical model is proposed to describe the limb’s dynamics whose results are in good agreement with the experimental data. The model shows that more than 65 % of the elastic-potential energy to power the limb is dissipated by drag/friction effects. This key aspect must be considered when developing efficient devices for applications such as lithotripsy.
Multiwavelength confocal fiber optic microscopy
Authors: Sosa-Acosta J A , Sánchez-Pérez C A
Published: March 2021

We present a multiwavelength fiber optic confocal microscope (MCFOM) based on the use of a wide spectral emission light source and some commercially available fiber optic components to make a reliable and compact system. We use single mode fiber optics SMF-28 to illuminate and collect the reflected light from the sample avoiding the use of a pinhole as a filter for the unfocused planes; as well as two lenses to collimate the light. The chromatic aberration produced by the lenses is used to interrogate several planes simultaneously, eliminating the confocal scanning movement obtaining an average confocal resolution of 4 μm and a surface scanning resolution of 1 μm. We demonstrated enough sensitivity to scan biological samples with a depth of penetration of 26 μm showing the potential use of this proposal in research laboratories as an alternative low cost confocal microscopy.
Neural network within a Bayesian inference framework
Authors: Gómez-Vargas Isidro , Esquivel Ricardo Medel , García-Salcedo Ricardo , Vázquez J Alberto
Published: March 2021

In Bayesian inference, the likelihood functions are evaluated thousands of times. In this paper we explore the use of an Artificial Neural Network to learn how to calculate the likelihood function and thus speed up the Bayesian inference process. We test the performance of the neural network on a parameter estimation of the standard cosmological model and show that this method can reduce the computational time.
Comparative study of the optical response in thin films of CdS:In
Authors: Molina J , Horta S D , Espejo-Bayona L , Castillo S J , Avila D A
Published: March 2021

In this investigation, thin films of indium-doped CdS and CdS were synthesized using the chemical bath deposition technique. These thin films were characterized by optical transmission, optical reflection, diffraction index and optical band gap. The optical spectra reveal that the optical transmission response increases with the concentrations of indium and the refractive index decreases. The CdS:In samples with 1cM, 2cM and 3cM the optical band gap is 2.50 eV, 2.74 eV, and 2.90 eV respectively.
Optimal relations for the allocation and effectiveness of the heat exchangers (hot and cold side) of an irreversible regenerative Stirling cycle
Authors: Alanis-Padrón R , Aragón-González G , León-Galicia A , Morales-Gómez J
Published: March 2021

A stationary irreversible regenerative Stirling cycle model, with two sources of irreversibilities (finite rate of heat transfers and heat leak), is analyzed. The aim of this work is to obtain the criterion of partial optimization presented in [3]. Since with this criterion, the optimal relations for the allocation and effectiveness of the heat exchangers of Carnot-like power plant are obtained; when two design rules are applied, alternatively: internal thermal conductance fixed, or areas fixed. These optimal relations are the same for maximum specific power and efficiency. As an instance, after the substitution of these optimal values in the specific power and efficiency, the maximum specific power and efficiency are obtained. Then the maximum efficiency and specific power are compared, and it is found that the maximum efficiency is greater than maximum specific power for both design rules.
Molecular dynamics for Ti-Ni dimer adsorbed on pristine and defective graphene
Authors: Arellano J S , Cruz Guerrero Harum Hueman
Published: March 2021

Motivated by the oxidation and corrosion processes of the nitinol alloy that has been used in biological applications, we show initial first principles calculations for the interaction of the Ti-Ni dimer, the simplest nitinol alloy, with a graphene layer, (gl). We have selected the graphene layer for the interaction, because our results can be compared with similar results for the interaction of many substances with a graphitic system as the gl. The results of several relaxations of the system Ti-Ni-gl shows that the dimer has been adsorbed to the gl. Temperatures of 300, 800, 1100 and 1300 K are not enough to desorb the dimer from the gl, these results are obtained from the molecular dynamics for those temperatures. The metallic character of the system is obtained from the density of states and projected density of states. Similar results are obtained for the interaction of the dimer when there are one or two carbon vacancies on the gl.
Characterization by FTIR spectroscopy of degradation of polyethylene films exposed to CO2 laser radiation and domestic composting
Authors: Martínez K I , González R , Soto J J , Rosales I
Published: March 2021

Polyethylene (PE) is a non-biodegradable polymer and accumulate easily on environment due its high molecular weight. In order to reduce this problem low-density (LDPE), high-density (HDPE) and biodegradable (BIO-PE) polyethylene films were exposed to CO2 laser radiation at different fluences and to domestic composting, the effects of CO2 laser radiation and domestic composting were characterized by FTIR spectroscopy. LDPE, HDPE and BIO-PE exposed to CO2 laser radiation underwent thermodegradation reactions causing changes in LDPE, HDPE and BIO-PE chemical and physical properties due to chain scission. LDPE, HDPE and BIO-PE biodegradation reactions leading to the formation of carbonyl (C=O), vinyl (CH2=CH) and hydroxyl (OH) groups.
Partial feedback linearization for a path control in a gantry crane used in lifting machinery in civil engineering
Authors: Ospina-Henao P , Carrillo-Suárez A , Guarín-Martínez L , Ortíz-Blanco A , Peñaranda-Vega J
Published: March 2021

This paper presents an alternate form for the dynamic modelling of a mechanical system that simulates in real life a gantry crane type, using Euler Lagrange classical mechanics, which allows find the equations of motion that our model describes. In order to verify the theoretical results obtained, a comparison was made between solutions obtained by simulation in SimMechanics-Matlab and Euler Lagrange equations system, has been solved through Matlab libraries for solving equations systems of the type and order obtained. Based on the partial feedback linearization, an improved nonlinear controller is analyzed and designed for the movement of an overhead crane or industrial shed. Three control inputs composed of bridge movement forces, carriage displacement, and pendulum or load angle are used to handle the state variables consisting of bridge movement, carriage movement, load displacement, and angle of turn of the same. The objective is to bring the mass of the pendulum from one point to another with a specified distance without the oscillation from it, so that, the answer was overdamped. The asymptotic stability of Lyapunov is also studied and the control scheme is of position of the load, constituted by the non-linear feedback of the actuated and non-actuated states. To verify the quality of the control process, verify numerical simulations. The proposed controller asymptotically stabilizes all states in the system.
Ab initio simulation of the effects of substitutional doping of oxygen in the semifullerene (C30)
Authors: Canales-Lizaola M , Ramirez-de-Arellano J M , Arellano J S , Magaña L F
Published: March 2021

Using first principles calculations, we studied the effects of substitutionally doping a 30-atom semifullerene (C30) with oxygen atoms, within the Density Functional Theory (DFT) and the pseudopotential formalism. We analyzed two C30 structures, one with a pentagonal and one with a hexagonal base. In both cases, the substitutionally absorbed oxygen atoms break the bonds between pentagons and hexagons of the semifullerene. We show that each semifullerene breaks into two geometrically flat structures, one of them being consistent with a known ring isomer of the fullerene C20. We used the Quantum ESPRESSO package code and the generalized gradient corrected Perdew-Burke-Ernzerhof (PBE) approximation for the exchange and correlation functional.
Phonocardiography in an Echocardiography room
Authors: Granados J , Rodríguez J A , Tavera F , Cid A , González A M , Hernández R T , Velázquez J M
Published: March 2021

In Mexico City at Universidad Autónoma Metropolitana Azcapotzalco (UAMA), with the aim to build a Computerized Diagnostics System of Cardiac Diseases based on the sound emitted by the heart, a research project is conducting. Cardiac sound is captured in a computer through a data acquisition system which it transforms in an image that will be analyzed later. Along years, several methods had been developed in different institutions of various countries looking for identify in phonocardiograms cardiac pathologies, some of them using complex mathematical algorithms for medical sector, which make difficult to understand and apply. At UAMA we can recognize image alterations of acoustic wave by means of a visual and computerized method in which its possible identify possible damages in the different heart’s components. To get a set of images of phonocardiograms of people with different heart disease, diagnosed and being treated, phonocardiograms were taken to ambulatory patients seen in the Echocardiography office at a High Specialty Hospital. We show the obtained images and his correlation with the diagnosed cardiac diseases.
Numerical Study of the movement of a mobile object in different trajectories with a coupled pendulum
Authors: Espíndola R , Valle G Del , Hernández G , Muciño D
Published: March 2021

Coupled systems are studied within classical mechanics, we study and analyse numerically the movement of the mobile object when it moves in a single dimension (y direction) with the pendulum oscillations: 1) in 2D (zy-plane) and 2) 3D (surface xyz). Subsequently, the movement of the object is studied when it moves in a circle of radius R with the same oscillation conditions referred in the pendulum. We obtained the numerical solutions of this system as well as the analysis for the different phase diagrams and the numerical solution for the intersection of the trajectory and surface, to begin with the study of chaos of this system.
Optimization of heat engines using different heat transfer laws by means of the method of saving functions
Authors: Barranco-Jiménez M A , Pacheco-Paez J C , Angulo-Brown F
Published: March 2021

In 2000 Velasco et al [1] introduced a new optimization criterion for the CA-engine model in terms of a profitable type process in the operation of a power plant model. This approach is based on using the so-called saving function as a measure of possible reduction of undesired side effects in heat engine operation. Velasco et al [1] defined two saving functions; one associated with fuel consumption and another associated with thermal pollution, where each saving function takes into account three weight coefficients that measure the participation degree of the corresponding process in the optimization criterion. We made use of this criterion to analyse the Novikov’s power engine model [2] but by using different heat transfer laws: Newtonian and Dulong-Petit (DP) heat transfer laws [3]. We compare our results with those reported by Velasco et al [1]. Our results show a saving in fuel consumption of approximately 44% and a reduction in thermal pollution of 42% with respect to the operating regime of maximum power, a value that is in agreement with some reported in the literature.
Numerical modeling of low strength reinforced concrete column strengthened with CFRP jacketing
Authors: Kurniawan P , Kasyanto H , Mauludin L M
Published: March 2021

Reinforced concrete column strengthened with Carbon Fiber Reinforced Polymer (CFRP) has been investigated numerically. Reinforced concrete column with low compression strength is used in this study. Concrete column is modeled by 3D solid elements with 8 nodes linear brick elements (C3D8R), whereas reinforcement bars modeled by 3D truss elements with 2 nodes first order elements (T3D2). In order to simulate concrete response in the specimen, concrete damage plasticity model with specifying damage parameters in both of compression and tension has been adopted in this paper. The specimen is subjected to uniaxial compression loading applied with displacement-controlled method. The effects of CFRP jacketing on reinforced concrete column with low compression strength are observed. The characteristic of reinforced concrete column combined with CFRP in terms of load-displacement behaviour and stress distributions are also evaluated. It is found that the numerical technique proposed in this study is quite efficient to predict the behaviour of low strength reinforced concrete column strengthened with CFRP with regard to the ultimate load, CFRP strain, and concrete strain distribution.
Students’ thinking process at the level of analysis in understanding square concept
Authors: Rizqika P , Sunardi  , Susanto  , Nuryami  , Shofyan A
Published: March 2021

Mathematics is important in all aspects of life. However, many students have problems understanding math problems, especially understanding the concept of geometry. Therefore, this study aims to describe the thinking process of students at the level of analysis in understanding the square concept. This research uses a qualitative approach. Data collection techniques were carried out by tests, interviews, and documentation. The research instrument used was the researcher, VHGT, test questions, and interview guidelines. The data source consisted of research subjects, namely two students of grade 8 with a level of analysis. The schematic of the square that S1 has built includes a square that has 4 sides and 4 angles. S1 undergoes an assimilation process when finding that a rectangle has 4 sides and 4 angles, where this property also belongs to square. S1 experiences a disequilibrium during the assimilation process when thinking that a rectangle is the same as a square visually. S1 experiences accommodation when it is found that squares and rectangles have different properties. S1 experiences a disequilibrium when understanding that the properties of a square and the properties of a rectangle are different. S2 experiences a disequilibrium during the assimilation process, which assumes that a rhombus is equal to a square. S2 experiences an accommodation process when understanding that a rhombus is not the same as a square. S2 experiences equilibrium when able to differentiate between a square and a rhombus.
The development of science, technology, engineering, art, and mathematics learning devices – lesson study for learning community to improve students’ creative thinking skill
Authors: Safik M , Hobri  , Yuianti N , Sarjono W , Sa’id I A
Published: March 2021

This research aimed to develop learning devices based on science, technology, engineering, art, and mathematics - lessons study for the learning community to improve students’ creative thinking skills on algebraic operation material. The learning devices developed were lesson plan, students’ workbook, and learning result test. The development model used Thiagarajan’s development model that consisted of four stages: define, design, develop, and disseminate. The subjects of this research were the eighth-grade students from (Islamic Junior High School) MTs. Nurul Islam Bades Pasirian. Students’ creative thinking abilities were measured using a creative thinking skill test. This research described the development process and validity, practicality, and effectiveness results. This research’s results were learning devices that met the criteria of validity, practicality, and effectiveness.
Development cognitive neuroscience based learning to use lesson study for learning community to increase mathematical literacy
Authors: Shodiq L J , Rokhmawati A
Published: March 2021

According to the results of observation with teachers it is known that students still considered topic of fractions were difficult. Students often made mistakes in changing and calculating the fraction of operation. One of the causes in their mathematics literacy was low. Mathematics learning commonly stimulated the work of the right brain and left brain only and ignoring anxiety of students when facing fraction of questions. However, the mathematics learning based on cognitive neuroscience is very needed. This research aims to produce learning model prototype in term of improving students’ mathematical literacy with the accompanying impact on the growth of communicative and collaborative skills. The developed model used is 4D (define, design, develop, and disseminate). Methods of data collection used observation, questionnaires, documentation techniques, and tests. The research was conducted in 3 cycles with lesson study for learning communities, each cycle went through 2 stages of a plan-do-see. The research subjects were 40 students in fifth grade of elementary school in the odd semester of 2020. The data were analyzed descriptive qualitatively through data reduction, data presentation, and conclusions. Based on data validation with learning technology experts, learning evaluation experts, and neurosains experts got a good value category, so that the learning model prototype was suitable to use in learning. The results of the pre-test post-test value of the learning implementation were analyzed using the paired sample T-Test obtained by t Stat = -2,87 < t Critical two-tail = 2,02 which was learning model prototype can improve students’ mathematical literacy. The Mathematical anxiety shown a decreasing, the communicative skill of students grew, the collaborative skill had not shown a significant increase. So it can be concluded that the learning model prototype is effective.
The effectiveness of chitosan from shrimp skin as a natural preservative for meatball
Authors: Gita R S D , Waluyo J , Dafik  , Indrawati
Published: March 2021

Meatball is one of the most favorite processed food in Indonesia it has delicious taste, tasty gravy, and affordable price. It is also easy to find a meatball stall in Indonesia, including Jember. Preservatives are usually used to maintain the condition of a meatball. Some preservatives, however, contain harmful substances, like formalin and borax. Both formalin and borax are not allowable for consumption since it may harm human’s health. The present study aimed to investigate a main ingredients for natural food preservative, to be further recommended as a preservative for meatball. The food preservative to be investigated in this study is chitosan made from shrimps shell wastes. To answer the research objective, a method used was an experiment of making chitosan solution. The concentration of chitosan created in the study is 1,5%. To test preservative efficacy of using chitosan, three treatments were given, (1) meatballs are coated with 1,5% of chitosan; (2) meatballs are mixed with 1,5% chitosan solution; and (3) meatballs without chitosan. These three treatments were observed and tested using organoleptic testing based on the length of storage, on day 1, 2, 3, and 4 in a room with a certain temperature. The parameters used for testing the preservatives included taste, color, odor, and texture. The study indicated that the 1,5% of chitosan solution was found effective for preserving meatballs naturally when used as coating.