Evaluación de la resistencia a la compresión del concreto 210 kg/cm2 utilizando agregados de la cantera Samanco 2021

El propósito principal de esta investigación es estudiar el diseño de la mezcla de concreto con piedra Zarandeada de la Cantera Samanco y comparar las propiedades mecánicas del concreto en el área de Chimbote 2021. Para su desarrollo, se utilizó relación igual de agua/cemento, sin factor de seguridad con una proporción de agregado fino y grueso (piedra Zarandeada) para evaluarse la resistencia a la compresión del concreto 210 kg/cm2 de dos años anteriores y con los mismos agregados fino y grueso, comparándose de tres diseños de mezcla, el tipo de investigación fue cuantitativa y diseño cuasi experimental, Según los resultados de la resistencia a la compresión del concreto, utilizando los agregados con su respectiva gradación, de la cantera Samanco del año 2019 , para los días 28 días de curado llego a un porcentaje de 102.42% pasando la curva proyectada, con una resistencia promedio de 215,09 kg/cm2, En el año 2020 a los 28 días de curado consiguió un porcentaje promedio de 113.10% pasando la curva proyectada, con una resistencia promedio de 237,51 kg/cm2, finalmente para el año 2021 , para los 28 días de curado alcanzó un porcentaje de 106,41% pasando la curva proyectada, con una resistencia promedio de 223,47 kg/cm2, finalmente nos damos cuenta que en los tres años de evaluación cumple con los parámetro s normativos de la resistencia a la compresión del concreto 210 kg/cm2, pero nos damos cuenta que en el año 2020 se obtiene mejor resultado esto es debido a la buena exploración y gradación de losa agregados.Tesi

Imagens hiperespectrais para o controle da qualidade de alimentos : híbridos de graos de cacau e vida de prateleira de sementes de chia

Orientador: Douglas Fernandes BarbinDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de AlimentosResumo: A imagem hiperespectral (HSI) permite a aquisição simultânea de informações espectrais e espaciais. Neste trabalho, HSI foi utilizado para o controle de qualidade de produtos agrícolas, que inclui a autenticação de híbridos de cacau e a estimativa do prazo de validade de sementes de chia. Para o trabalho com sementes de chia, as amostras foram armazenadas a 25, 35 e 45 ° C por 180 dias, para análises aceleradas do prazo de validade. Periodicamente, as amostras de chia eram removidas do armazenamento para obter imagens hiperespectrais (900 - 2500 nm), análise de acidez e perfil de ácidos graxos. O objetivo foi usar imagens hiperespectrais e análises multivariadas para desenvolver uma metodologia para estimar a vida de prateleira de sementes de chia, denominada Multivariate Accelerated Shelf Life Testing (MASLT). A Análise de Componentes Principais (PCA) foi usada para estudar a variabilidade durante o armazenamento e, em seguida, as pontuações do PC foram usadas para modelar a cinética e estimar os parâmetros da Equação de Arrhenius e, finalmente, para estimar a vida de prateleira. Além disso, pela primeira vez, uma nova estratégia foi proposta para validar essa metodologia, que chamamos de "Re-sampling", onde as amostras do conjunto de validação foram projetadas no conjunto de calibração com um número razoável de iterações. Os escores PC1 e gráficos cinéticos foram construídos ajustando os escores PC1 relacionados ao tempo versus o tempo por um modelo cinético fundido (R2> 0,85). Os espectros de sementes de chia onde a acidez aumentou em 75% a partir do valor inicial foram usados para calcular o valor de corte (-0,9853). As estimativas de vida de prateleira foram 1300, 798 e 90 dias para sementes de chia armazenadas a 25, 35 e 45 ° C, respectivamente. Pela primeira vez, uma metodologia confiável é proposta para validar que todas as amostras foram previstas corretamente usando as pontuações PC1. No segundo estudo, cinco híbridos de cacau foram cultivados e processados nas mesmas condições na CEPLAC (Medicilândia, Pará, Brasil). Os grãos de cacau foram então transportados para o Wallonie Research Center (Bélgica), onde foram obtidas imagens hiperespectrais na faixa de 1100 - 2500 nm. A análise parcial discriminante dos mínimos quadrados (PLS-DA) e a máquina de vetores de suporte (SVM) foram implementadas para classificar os híbridos de cacau, (1) duas classes de híbridos e (2) cinco classes de híbridos. Além disso, um novo conjunto de imagens foi usado para validação externa pixel a pixel. Os resultados mostraram que PLS-DA e SVM tiveramresultados comparáveis para modelos de duas classes (híbridos), mas o SVM (erro de previsão de 3,8 a 23,1%) foi superior ao PLS-DA (erro de previsão de 4,4 a 34,4%) quando todas as cinco classes de híbridos foram incluídas em um modelo. Os resultados de previsão pixel a pixel em um conjunto de imagens externas mostraram uma taxa de classificação correta de 50 a 100%. Os resultados para os modelos de duas classes e cinco foram comparáveis às técnicas de reação em cadeia da polimerase. Os resultados mostram o potencial do HSI para o controle de qualidade de produtos agrícolas, tanto para autenticação quanto para estimativa do prazo de validadeAbstract: Hyperspectral imaging (HSI) enables simultaneous acquisition of spectral and spatial information. In this work, HSI was used for quality control of agricultural products, which includes the authentication of cocoa bean hybrids and the estimation of shelf-life of chia seeds. Regarding the chia seeds study, samples were stored at 25, 35 and 45 ° C for 180 days, for accelerated shelf life analyzes. From time to time, chia samples were removed from storage to acquire hyperspectral images (900 - 2500 nm), acidity analysis, and fatty acid profile. The objective was to use hyperspectral images and multivariate analysis to develop a methodology for estimating the shelf-life of chia seeds, called Multivariate Accelerated Shelf Life Testing (MASLT). Principal Component Analysis (PCA) was used to study the variability during storage, and then, the PC scores were used to model the kinetics and estimate the parameters of the Arrhenius Equation, and finally to estimate the shelf life. Furthermore, for the first time a new strategy was proposed to validate this methodology, which we called "Re-sampling", where the samples from the validation set were projected onto the calibration set with a reasonable number of iterations. PC1 scores and kinetic charts were built fitting the time-related PC1 scores versus time by a fused kinetic model (R2 > 0.85). The spectra of chia seeds where acidity increased at 75% from initial value were used to calculate the cut-off value (-0.9853). The shelf life estimations were 1300, 798 and 90 days for chia seeds stored at 25, 35 and 45 °C, respectively. For the first time, a reliable methodology is proposed to validate that all samples were correctly predicted using PC1 scores. In the second study, cocoa beans hybrids (five) were grown and processed under the same conditions in CEPLAC (Medicilândia, Para, Brazil). The cocoa beans were then transported to the Wallonie Research Center (Belgium), where hyperspectral images in the 1100 - 2500 nm range were acquired. Partial least square discriminant analysis (PLS-DA) and Support vector machine (SVM) was implemented to classify cocoa bean hybrids, (1) two classes of hybrids and (2) five classes of hybrids. Additionally, a new set of images was used for external pixel-to-pixel validation. The results showed that PLS-DA and SVM demonstrate comparable results for two-class (hybrids) models, but SVM (3.8–23.1% prediction error) was superior to PLS-DA (4.4–34.4% prediction error) when all five classes (hybrids) were included in a model. Pixel-to-pixel prediction results on a set of external images showed a correct classification rate of 50 - 100%. The results for both the two-class models and the five-class model were comparable with polymerase chain reaction techniques. The results show the potential of HSI for quality control of agricultural products, both for authentication and estimation of shelf lifeMestradoEngenharia de AlimentosMestre em Engenharia de Alimentos2018/02500-4; 2019/04833-3; 2015/24351-288882.329557/2019-01FAPESPCAPE

Trends in application of NIR and hyperspectral imaging for food authentication

Food fraud can cause damage to consumer health and affect their confidence, destroy brands and generate large economic losses in the industry. Food authenticity allows to identify if food composition, geographical origin, genetic variety and farming system corresponds to what has been declared on the label. Although there are currently standardized methods to identify certain adulterants, the complexity of the food, the complexity of the supply chain and the appearance of new adulterants require the continuous development of analytical techniques to detect food fraud. NIR and Hyperspectral imaging (HSI) in tandem with chemometrics are non-destructive, non-invasive and accurate techniques for food authentication. This review focuses on NIR and HIS approaches to food authentication, including adulteration by substitution, geographical origin and farming system. In this context, the advances in NIR and HSI approaches reported since 2014 are discussed regarding their potential use in food authentication. Both techniques have shown to have efficiency, precision and selectivity to detect adulterants and identify geographic origin, genetic variety and farming system. Portability and remote access are shown as the next step for the industrialization of NIR and HSI devices

Data reduction by randomization subsampling for the study of large hyperspectral datasets

Large amount of information in hyperspectral images (HSI) generally makes their analysis (e.g., principal component analysis, PCA) time consuming and often requires a lot of random access memory (RAM) and high computing power. This is particularly problematic for analysis of large images, containing millions of pixels, which can be created by augmenting series of single images (e.g., in time series analysis). This tutorial explores how data reduction can be used to analyze time series hyperspectral images much faster without losing crucial analytical information. Two of the most common data reduction methods have been chosen from the recent research. The first one uses a simple randomization method called randomized sub-sampling PCA (RSPCA). The second implies a more robust randomization method based on local-rank approximations (rPCA). This manuscript exposes the major benefits and drawbacks of both methods with the spirit of being as didactical as possible for a reader. A comprehensive comparison is made considering the amount of information retained by the PCA models at different compression degrees and the performance time. Extrapolation is also made to the case where the effect of time and any other factor are to be studied simultaneously.J.P Cruz-Tirado acknowledges scholarship funding from FAPESP, grant number 2020/09198–1

Propiedades mecánicas de bandejas elaboradas con almidón de especies vegetales nativas y fibras de residuos agroindustriales

The aim of this study was to evaluate the effect of natural fibers derived from agro-industrial waste in density, weight and mechanical properties of the termoprensadas foams made of starch native species, such as sweet potatoes, oca and arracacha. The thermoforming process was carried out at a temperature of 145 ° C and a pressure of 60 bar. The baking time was 10-15 min depending on water content in the mixture. The trays were characterized by their density, weight, impact test, deflection tests, colorimetry, hardness, and fracturability values. The trays prepared by thermopressure based on sweet potato starch-bagasse fiber from sugar cane at 15%, and arracacha starch -peladilla asparagus fiber at 30% had higher values in flexural strength versus those made with other types of starches and fibers, including blank tests. Generally, the hardness of the trays is favored with increasing fiber, however fracturability decreases or does not improve the integrity of the polymeric matrix. The results shown in this study allow the preparation of biodegradable trays for various industrial applications.El objetivo de este trabajo fue evaluar el efecto de las fibras naturales obtenidas de residuos agroindustriales en la densidad, el gramaje y las propiedades mecánicas de las espumas termoprensadas elaboradas de almidón de especies nativas, como lo son el camote, la oca y la arracacha. El proceso de termoformado se llevó a cabo a una temperatura de 145 °C y una presión de 60 bar. El tiempo de horneado fue de 10-15 min dependiendo del contenido de agua en la mezcla. Las bandejas fueron caracterizadas por su densidad, gramaje, ensayo de impacto, ensayos de deflexión, colorimetría y sus valores de dureza y fracturabilidad. Las bandejas elaboradas por termopresión a base de almidón de camote-fibra de bagazo de caña de azúcar al 15%, y de almidón de arracacha-fibra peladilla de espárrago al 30% presentaron mayores valores en resistencia a la flexión frente a las elaboradas con otros tipos de almidones y fibras, incluyendo a pruebas en blanco. De manera general, la dureza de las bandejas se ve favorecida con el incremento de fibra, sin embargo, la fracturabilidad decrece o no mejora la integridad de la matriz polimérica. Los resultados mostrados en esta investigación permitirán la elaboración de bandejas biodegradables para distintas aplicaciones industriales

Influencia de la temperatura y velocidad del aire en la obtención de harina a partir de bazo de res (Bos indicus), con el máximo contenido de Hierro

Iron is an important mineral element in food, being found, among other foods, in beef spleen, with high iron content. The objective of this work was to determine the temperature and speed of air drying to obtain flour with maximum iron content from beef spleen (Bos indicus L.) and to determine the physicochemical and organoleptic characteristics of the flour obtained. The beef spleen, previously selected, was washed and cut into thin slices, subjected to a tray dryer, which, in turn, were subjected to three temperatures (45, 55 and 65 ºC) and three hot air speeds (1.5, 2.5 and 3.5 m/s), followed by grinding and sieving on a 220-micron mesh. A DCA design was applied with a factorial arrangement of 3Ax3B, with 3 replicates. Iron concentration was determined using a spectrophotometer at a wavelength of 525 nm. Treatment T5 (55°C and 2.5 m/s) presented the highest iron concentration with 135.02 mg/100g, with 1.01 %; 6.13; 5.54 % and 9.94 % of acidity, pH, ash and moisture, respectively; presenting, at the same time, good organoleptic acceptability.El hierro es un elemento mineral importante en la alimentación, encontrándose, entre otros alimentos, en el bazo de res, con alto contenido de hierro. El presente trabajo tuvo como objetivo determinar la temperatura y velocidad del aire de secado para obtener harina, con el máximo contenido de hierro, a partir de bazo de res (Bos indicus L.) y determinar las características fisicoquímicas y organolépticas de la harina obtenida. El bazo de res, previamente seleccionado, fue lavado y cortado en finas láminas, se sometió a un secador de bandejas, las que, a su vez, se sometieron a tres temperaturas (45, 55 y 65 ºC) y tres velocidades de aire caliente (1.5; 2.5 y 3.5 m/s); procediéndose, luego, a moler y tamizar en una malla de 220 micrones. Se aplicó un diseño DCA con arreglo factorial de 3Ax3B, con 3 repeticiones. Con ayuda de un espectrofotómetro, a una longitud de onda de 525 nm, se determinó la concentración de hierro. El tratamiento T5 (55°C y 2.5 m/s) presentó la mayor concentración de hierro con 135.02 mg/100g, con 1.01 %; 6.13; 5.54 % y 9.94 % de acidez (pH) y una buena aceptabilidad organoléptica

Teoría del hormigón armado tomando en consideración el esfuerzo cortante

This article is an advanced summary of the original theory elaborated by Messrs. López Jamar and Tirado Cruz, on compound bending in reinforced concrete parts, taking account of shear effects. The authors assume the structure to be similar to an open web girder. The top chord is the uncracked zone, and is assumed to withstand eccentric compression and shear, in the same way as the uncracked diagonal portions of concrete, between cracks. The bottom chord consists of the longitudinal reinforcement and the complementary series of diagonal uncracked concrete portions (which may no actually exist). These are subject to almost pure tensile loads. A parabolic distribution of longitudinal stresses is supposed initially, and from this the normal and tangential forces on the non cracked zone is precisely obtained. Also assuming a parabolic stress distribution for the stirrups, the efficient stress distribution laws in the cracked zone of the concrete are obtained. These stress laws make it possible to study the partial strength of the cracked and uncracked zones: the latter, because of its intrinsic strength. Thus, the shear is mainly dependent on the relative strain of the cracked zone. There are therefore four possible ways of reaching ultimate failure: simultaneous transversal failure of concrete and stirrups; longitudinal reinforcement failure; compression failure and total failure of the structure. The complex resulting system of equations can be solved by means of computers. Graphical and tabulated results are obtained for the various cases and systems of reinforcement. A first check of the theory has been made by means of a test.Este artículo es un resumen, anticipo de la teoría original de los señores López Jamar y Tirado Cruz, sobre flexión compuesta de piezas de hormigón armado, tomando en consideración el esfuerzo cortante. La pieza se asimila a una viga en celosía; la cabeza superior, constituida por la faja sin fisurar, trabaja a compresión excéntrica con esfuerzo cortante, lo mismo que las diagonales de hormigón entre fisuras. La cabeza inferior, constituida por la armadura longitudinal, y la otra serie de diagonales o montantes (que pueden no existir), trabajan prácticamente a tracción pura. Partiendo de una ley parabólica de tensiones normales longitudinales, se obtienen rigurosamente las de tensiones tangenciales y normales verticales de la faja no asurada. Asimismo, partiendo de una ley parabólica de las tensiones de los estribos, se hallan las leyes de tensiones «eficaces» del hormigón de la zona fisurada a lo largo de la sección transversal recta. Estas leyes de tensiones permiten estudiar las resistencias parciales de las fajas fisuradas y sin fisurar, esta última mediante la resistencia intrínseca. Resulta así que el esfuerzo cortante es función principalmente de la deformación unitaria horizontal relativa de la fibra o nivel que alcanzan las fisuras. Del estudio se deducen cuatro posibles formas de agotamiento: transversal simultáneo del hormigón y estribos, armadura longitudinal, fibra más comprimida y agotamiento superior de la pieza. El complicado sistema de ecuaciones resultante se resuelve electrónicamente, obteniéndose listados numéricos y gráficos para los diferentes casos y armaduras posibles, habiéndose efectuado una pri- mera comprobación mediante ensayos

Una teoría de la flexión con esfuerzo cortante en piezas de hormigón armado

En la Monografía número 221, el Instituto Eduardo Torroja de la Construcción y del Cemento ha publicado recientemente el trabajo arriba titulado, original de los ingenieros citados. Creemos constituye un interesante intento de explicar el comportamiento del hormigón armado en el caso de existir esfuerzos cortantes, simultáneamente con la flexión simple o compuesta. Actualmente se están realizando una serie de ensayos de rotura de vigas, en nuestros Laboratorios y bajo el patronato del Instituto, para contrastar esta teoría. Pero como consideramos interesará el asunto a muchos de nuestros lectores, exponemos a continuación un resumen de los principales puntos de aquélla y su comparación con los criterios clásicos que se han venido siguiendo hasta ahora

Properties of baked foams from oca (Oxalis tuberosa) starch reinforced with sugarcane bagasse and asparagus peel fiber

ABSTRACT The aim of this work was evaluate the effect of the addition of sugarcane bagasse and asparagus peel fiber on the physical and mechanical properties of baked foams based on oca starch. Low concentrations of fiber reduce the density of the foams and the addition of fiber does not improve the flexural strength of the foams, but generates harder and deformable trays. High concentrations of sugarcane bagasse fiber generate more compact trays with a lower water absorption capacity than the control. Foams with asparagus peel fiber showed higher rates of thermal degradation than the control but not so extensive as to affect their applicability

Review and new perspectives on non-layered manganese compounds as electrode material for Sodium-Ion batteries

After more than 30 years of delay compared to lithium-ion batteries, sodium analogs are now emerging in the market. This is a result of the concerns regarding sustainability and production costs of the former, as well as issues related to safety and toxicity. Electrode materials for the new sodium-ion batteries may contain available and sustainable elements such as sodium itself, as well as iron or manganese, while eliminating the common cobalt cathode compounds and copper anode current collectors for lithium-ion batteries. The multiple oxidation states, abundance, and availability of manganese favor its use, as it was shown early on for primary batteries. Regarding structural considerations, an extraordinarily successful group of cathode materials are layered oxides of sodium, and transition metals, with manganese being the major component. However, other technologies point towards Prussian blue analogs, NASICON-related phosphates, and fluorophosphates. The role of manganese in these structural families and other oxide or halide compounds has until now not been fully explored. In this direction, the present review paper deals with the different Mn-containing solids with a non-layered structure already evaluated. The study aims to systematize the current knowledge on this topic and highlight new possibilities for further study, such as the concept of entatic state applied to electrodes