Abstract
The recording of temperatures in different positions in the firing process in an intermittent kiln to produce ceramic materials is presented, which led to the energy evaluation, determining ...the heat used for the clay firing process and the heat losses. In addition, a study of the emissions of pollutant gases released into the environment was carried out, as stipulated in the protocol of control, and monitoring of stationary source. In the energy balance, large energy losses were detected in heat accumulation in the masonry of 7.20×10
6
KJ of the energy supplied, representing 16.99%, and in the kiln walls of 5.20×10 KJ, representing 12.17%. As a result, it is necessary to make constructive and operative changes in the operation of the kilns, which will lead to the recovery of residual heat in the use of drying of parts, drying, and preheating of combustion air, reducing energy consumption and emissions of pollutants into the atmosphere. The average concentration of particulate matter released into the environment was 1056.60 mg/m
3
, 422% higher than the standard, affecting people’s health.
Abstract
In buildings, each component contributes to resisting seismic forces and an important part in this activity are the masonry walls composed of: fired clay solid brick of 120 mm width and ...horizontally perforated clay blocks of 100 mm and 150 mm width. The main focus of this research is to determine the flexural strength of the horizontally perforated clay block-mortar joint, using different types of mortar as established in the “Reglamento Colombiano de Construcion Sismo Resistente” for four suppliers used in the municipality of Ocaña, Colombia. A semi-automatic machine that takes into account the physics in the application of loads was designed to carry out the flexural test in mortar-block joints. The average flexural strength in mortar-block joints was determined for three types of mortar corresponding to 0.219 MPa, 0.232 MPa, and 0.291 MPa respectively, for the municipality of Ocaña, Colombia. This research established a direct relationship between the compressive strength of the mortar and the flexural strength of the 100 mm wide horizontally perforated clay mortar-block joint. A physical comparison was made in terms of the compressive strength of the prism and the flexural strength of the clay mortar-block joint with that obtained by other researchers in India and found quite similar results.
Magnetite Fe
3O
4 nanoparticles of controlled size within 6 and 20
nm in diameter were synthesised by thermal decomposition of an iron organic precursor in an organic medium. Particles were coated ...with oleic acid. For all samples studied, saturation magnetisation
M
s is size-independent, and reaches a value close to that expected for bulk magnetite, in contrast to results in small particle systems for which
M
s is usually much smaller due to surface spin disorder. The coercive field for the 6
nm particles is in agreement with coherent rotation, taking the bulk magnetocrystalline anisotropy into account. Both results suggest that the oleic acid molecules covalently bonded to the nanoparticle surface yield a strong reduction in the surface spin disorder. However, although the saturated state may be similar, the approach to saturation is different and, in particular, the high-field differential susceptibility is one order of magnitude larger than in bulk materials. The relevance of these results in biomedical applications is discussed.
Abstract
Buildings are generally composed of reinforced concrete elements and understanding the response of these elements to the actions to which they are subjected is crucial for the design of a ...feasible, safe, and economic structure. This paper analyzes 3D finite element modeling using the commercial software ANSYS for a reinforced concrete beam subjected to three-point bending, simply supported with a doubly reinforced cross-section and transverse reinforcement. This work validated the results of a numerical model with theoretical results for a reinforced concrete beam subjected to monotonic loading. This work was carried out for the civil engineering program of Universidad Francisco de Paula Santander, Ocaña, Colombia, in order to reduce student attrition, increase motivation, and broaden the professional skills of future graduates.
This investigation analyzed the uncertainty of compression resistance in the average statistics, standard error, asymmetry, kurtosis and confidence intervals taking into account the Bootstrap method. ...The implementation of the Bootstrap method in determining the physical properties of the material used in the construction of buildings, is a fundamental tool to establish the physical behavior of existing buildings. The application of the Bootstrap method allowed estimating the statistics for the reported dosages with different samples; 1:2:2, allowing to estimate statistics. The results allowed to determine the probability density function of the average value of the compressive strength and with it, probabilistic resistance values can be established. This research determined statistical results of the compressive strength vital to carry out revision, vulnerability and structural reinforcement studies of existing buildings in the municipality of Ocaña, Colombia.
Abstract
In structural projects, ensuring system performance within the established specifications with a maximum level of safety and taking into account the economic constraints of the project is ...one of the main objectives of structural design. The risks to which any physical system is subjected are called failure probability and are assessed by applying structural reliability analysis methods. The objective of the structural reliability analysis is to ensure that the strength of the elements of the structure is greater than the imposed strength demand over the service life of each of the structural elements. Structural design variables are physical quantities in structural reliability and are considered random, and can be represented in a random vector. The failure probability of a structure is obtained from the evaluation of the uncertainties inherent to the physical variables of the project, through the probability distributions of the random variables. The objective of this work was the application of polynomial chaos expansion to evaluate the failure probability in limit state functions found in the literature using numerical simulation, in order to decrease the sample size for each random variable compared to those needed using Monte Carlo simulation. This research showed that the difference between the sample size between polynomial chaos expansion and Monte Carlo simulation is 5%, saving time and computational effort.
Abstract
The study of the phenomenon of electrical conduction has its origin in two historical antecedents, Fourier’s law and Maxwell’s equations. The mathematical formulation of electrical ...conduction has been extensively studied and the differential equations describing the phenomenon are known. The mathematical solution of the physical model of electrical conduction employs different techniques, the best known of which are the Fourier series, Grenn functions and Bessel equations. The purpose of this research is to present a model of heat conduction with the use of electric current that dissipates heat by convection. The research proposes a method for solving the mathematical model associated with the conduction phenomenon using linear algebra. The advantage of using linear algebra will allow to establish a step-by-step procedure that could be used to study phenomena related to heat conduction, in addition to allowing its implementation through programming. In order to establish the fit of the method derived from linear algebra, the analytical solution and the solution proposed in the research were compared to verify that the proposed method fits with a small error.
Abstract
It is claimed that most of the fundamental principles that govern the physical phenomena of interest in engineering applications can be described by differential equations. Therefore, the ...ability to analyze, solve and understand differential equations is essential for decision-making in the applied areas. In this sense, studying efficient methods to solve differential equations is a fundamental contribution in advancing the understanding of relevant physical models in engineering applications. The purpose of this research allowed to study the differential equation associated with Fourier’s heat transfer law and calculate its solution by two different methods than the traditional method. From this context, the study is related to the phenomenon of heat conduction in a metal bar under ideal conditions to later carry out its application in a particular case. First, the solution of the differential equation that models the physical phenomenon derived from the use of Fourier’s physical heat law is calculated with the use of statistical tools; then, a solution scheme is implemented using method of lines. Given the nature of the investigation, the solutions by both methods are compared about what is expected in the physical interpretation of Fourier’s law.
Relevant electrochemical processes present rate equations with non-unity reaction orders. For such reactions, an analytical treatment is developed for the stationary voltammetric response and the ...surface concentrations at the rotating disc electrode and at microelectrodes of any shape, as frequently/preferably employed to reveal their electrode kinetics. The expressions deduced are applicable when one or both redox species are initially present and cover any degree of reversibility.
From the general solution obtained, the limit cases of fully reversible and irreversible reactions are derived. By linearizing the current–potential response of the former, the reaction orders can be determined, as well as the value of the reversible half-wave potential that strikingly depends on whether one or both species are initially present in contrast with the case of unity orders. For irreversible processes, the linearization of the complete current–potential response is also possible and it enables us to extract the reaction order and the half-wave potential. An expression for the latter is given as a function of the heterogeneous rate constant and the mass transport coefficient. Additional protocols of kinetic analysis are discussed on the basis of Tafel and Koutecký-Levich-like plots.
Abstract
Improvements in cost and speed of next generation sequencing (NGS) have provided a new pathway for delivering disease diagnosis, molecular typing, and detection of antimicrobial resistance ...(AMR). Numerous published methods and protocols exist, but a lack of harmonisation has hampered meaningful comparisons between results produced by different methods/protocols vital for global genomic diagnostics and surveillance. As an exemplar, this study evaluated the sensitivity and specificity of five well-established in-silico AMR detection software where the genotype results produced from running a panel of 436
Escherichia coli
were compared to their AMR phenotypes, with the latter used as gold-standard. The pipelines exploited previously known genotype–phenotype associations. No significant differences in software performance were observed. As a consequence, efforts to harmonise AMR predictions from sequence data should focus on: (1) establishing universal minimum to assess performance thresholds (e.g. a control isolate panel, minimum sensitivity/specificity thresholds); (2) standardising AMR gene identifiers in reference databases and gene nomenclature; (3) producing consistent genotype/phenotype correlations. The study also revealed limitations of in-silico technology on detecting resistance to certain antimicrobials due to lack of specific fine-tuning options in bioinformatics tool or a lack of representation of resistance mechanisms in reference databases. Lastly, we noted user friendliness of tools was also an important consideration. Therefore, our recommendations are timely for widespread standardisation of bioinformatics for genomic diagnostics and surveillance globally.
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