Universidad Centroccidental Lisandro Alvarado
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SIMULACI 3N NUM\uc9RICA DEL COMPORTAMIENTO ESTRUCTURAL DE PERFILES TUBULARES SOMETIDOS A FATIGA DE ULTRA-BAJO CICLAJE
Get PDFEn el presente trabajo de investigaci\uf3n se estudia el comportamiento num\ue9rico de perfiles estructurales de acero de pared delgada, de producci\uf3n nacional venezolana Conduven ECO, de secci\uf3n transversal cuadrada, construidos en forma de viga tipo cantil\ue9ver, bajo los efectos de Fatiga de Ultra-Bajo Ciclaje. Se realizaron ensayos experimentales donde se aplicaron historias de desplazamientos c\uedclicos, con muy baja velocidad y actuando en un rango que va desde el esfuerzo cedente hasta el esfuerzo \ufaltimo del elemento, obteniendo una degradaci\uf3n de la capacidad resistente de los perfiles, estos resultados experimentales fueron comparados con las simulaciones num\ue9ricas realizadas mediante un programa comercial de elementos finitos, obteniendo resultados satisfactorios.
Palabras clave: fatiga de ultra-bajo ciclaje; elementos tubulares de acero; falla por pandeo local
ABSTRACT
In the present work of investigation the numerical behavior of structural profiles of steel of thin wall is studied, of Venezuelan national production Conduven ECO, of square cross section, constructed in the form of beam type cantilever, under the effects of Fatigue of Ultra-Low Cycling. Experimental tests were carried out where histories of cyclic displacements were applied, with very low speed and acting in a range that goes from the yielding effort to the last effort of the element, obtaining a degradation of the resistant capacity of the profiles, these experimental results were compared with the numerical simulations made through a commercial program of finite elements, obtaining satisfactory results.
Keywords: ultra-low cycling fatigue; tubular steel elements; fails due to local buckling <br
ESTUDIO F\ucdSICO MEC\uc1NICO DE CONCRETOS SUSTITUIDOS CON POLVO DE S\ucdLICE EXPUESTOS EN AMBIENTE AGRESIVO SIMULADO
No full textEl presente trabajo de investigaci\uf3n tuvo como prop\uf3sito ensayar probetas cil\uedndricas normalizadas, para evaluar sus propiedades en un ambiente de exposici\uf3n simulado por inmersi\uf3n en soluci\uf3n de NaCl al 3%. Se realiz\uf3 la evaluaci\uf3n f\uedsica y mec\ue1nica en probetas cil\uedndricas armadas de 30 cm de alto y 15 cm de di\ue1metro, de concretos elaborados con sustituci\uf3n parcial del cemento por dosis s\uedlice en 10% y 15% relaciones agua cemento de 0,45 y 0,65 y resistencia de dise\uf1o de 250 Kgf/cm2. En un per\uedodo de 5 meses se analiz\uf3 la influencia de las sustituciones de polvo s\uedlice en las mezclas de concreto con respecto a las mezclas patr\uf3n, obteniendo un aumento en la resistencia mec\ue1nica con respecto a la de dise\uf1o, en la relaci\uf3n a/c 0,45, para la relaci\uf3n a/c 0,65 alcanz\uf3 valores aceptables en cuanto a las mezclas sustituidas con respecto a la resistencia mec\ue1nica comparada con la de dise\uf1o, en cuanto a los ensayos de porosidad y absorci\uf3n capilar no fueron satisfactorios para ninguna relaci\uf3n a/c probablemente por la falta de curado previo a la exposici\uf3n.
Palabras clave: ambiente agresivo; concreto sustituido; polvo de s\uedlice; resistencia a la compresi\uf3n.
ABSTRACT
The present research resulted in a standardized laboratory test for the evaluation of properties in a simulated exposure environment by immersion in 3% NaCl solution. The physical and mechanical evaluation was performed on reinforced cylindrical specimens of 30 cm high and 15 cm in diameter, made of concrete with partial replacement of the cement by dose silica in
10% and 15% water cement ratio of 0,45 and 0,65 and design strength of 50 Kgf/cm2. Settlement tests, porosity, capillary absorption and mechanical resistance were performed In a period of 5 months, the influence of the substitutions of silica dust in the concrete mixtures with respect to the standard mixtures was analyzed, obtaining an increase in the mechanical resistance with respect to the design, in the ratio a/c 0,45, for the a/c ratio 0,65 reached acceptable values for the substituted mixtures with respect to the mechanical strength compared with the design, as for the porosity and capillary absorption tests were not satisfactory for any relation to a/c probably due to lack of curing prior to exposure.
Keywords: aggressive environment; substituted concrete; silica powder; compression resistance. <br
EFECTO DE LA FERTILIZACI 3N ORG\uc1NICA E INORG\uc1NICA SOBRE EL CRECIMIENTO DE TOMATE (Solanum Lycopersicum) EN AMBIENTES PROTEGIDOS
Get PDFEl tomate (Solanum lycopersicum) es una de las hortalizas de mayor producci\uf3n a nivel mundial, para mantener sus rendimientos es necesario una adecuada fertilizaci\uf3n, por lo que se deben buscar fuentes de fertilizantes que suplan los nutrientes requeridos por las plantas, por ello se evalu\uf3 el efecto de diferentes tratamientos de fertilizaci\uf3n org\ue1nica e inorg\ue1nica sobre el crecimiento de plantas de tomate, para ello se condujo una investigaci\uf3n a nivel de invernadero, se realiz\uf3 un experimento completamente al azar donde se evalu\uf3 el efecto de 5 tratamientos: (T0) testigo, (T1) fertilizaci\uf3n inorg\ue1nica, (T2) compost, (T3) vermicompost, (T4) compost +vermicompost, los cuales fueron replicados 5 veces para 25 unidades experimentales. Durante el ciclo del cultivo se evaluaron variables biom\ue9tricas: altura de planta, n\ufamero de hojas, di\ue1metro del tallo y los cambios en las variables ed\ue1ficas: materia org\ue1nica, f\uf3sforo, potasio, calcio, magnesio, conductividad el\ue9ctrica y pH. El an\ue1lisis estad\uedstico se realiz\uf3 aplicando un an\ue1lisis de varianza y agrupaci\uf3n DGC con un valor de probabilidad p
Palabras Clave: Agroecolog\ueda, fertilidad, horticultura, sostenibilidad, vermicompost.
ABSTRACT
The tomato (Solanum lycopersicum) is one of the vegetables with the highest production in the world, to maintain its yields it is necessary improve fertilization to soil, so it is necessary that fertilizers supply the nutrients required by the plants, for this reason the effect of different treatments of organic and inorganic fertilization on the growth of tomato plants was evaluated, for this a research was conducted at greenhouse level, a completely randomized experiment was carried out, where the effect of 5 treatments was evaluated: (T0) control, (T1) inorganic fertilization, (T2) compost, (T3) vermicompost, (T4) compost + vermicompost, which were replicated 5 times for 25 experimental units. During the crop cycle, biometric variables were evaluated: plant height, number of leaves, stem diameter and changes in edaphic variables: organic matter, phosphorus, potassium, calcium, magnesium, electrical conductivity and pH. The statistical analysis was carried out applying a variance analysis and DGC grouping with a probability value p
Keywords: Agroecology, fertility, horticulture, sustainability, vermicompost. <br
PURIFICACI 3N DE LA PAPA\ucdNA DEL L\uc1TEX DE LA LECHOSA Y CUANTIFICACI 3N DE LA ACTIVIDAD ENZIM\uc1TICA
No full textEl l\ue1tex es un flu\ueddo tixotr\uf3pico contenido en vasos lat\uedferos bajo el exocarpo de la lechosa. Su contenido de enzimas proteol\uedticas lo ha hecho un sujeto muy estudiado, en particular la papa\uedna, que a\ufan estando entre los menores constituyentes de esas enzimas es la de mayor uso industrial. En esta investigaci\uf3n se purific\uf3 la papa\uedna del l\ue1tex de la lechosa y se evalu\uf3 el efecto de dos condiciones de secado sobre la actividad enzim\ue1tica. Se extrajo el l\ue1tex del exocarpo de la fruta, se deshidrat\uf3 bajo dos condiciones (C), C1: 25\ubaC y 20 h y C2: 60\ubaC y 4 h, se calcul\uf3 el rendimiento seco y se caracteriz\uf3. Posteriormente, se purific\uf3 la papa\uedna y se cuantific\uf3 la actividad enzim\ue1tica; luego se estim\uf3 el factor de purificaci\uf3n (FP) y finalmente, se determin\uf3 la actividad proteol\uedtica evaluando la eficiencia de remoci\uf3n de prote\uednas de un efluente industrial. El l\ue1tex seco en C1, con un rendimiento de 1,38%, se caracteriz\uf3 por poseer 52 \ub0Brix, pH 6,26, humedad 8,50%, 39,48% de cenizas; mientras que en C2 rendimiento 1,45%, 42,96 \ub0Brix, pH 6,76, humedad 4,73%, 30,80% de cenizas. El FP fue de 91,19-108,64%. Finalmente, se demostr\uf3 el poder de la enzima al determinar la eficiencia de remoci\uf3n del contenido proteico de un efluente l\ue1cteo obteni\ue9ndose que, con la papa\uedna purificada, se removi\uf3 en promedio 60,03%.
Palabras Clave: Carica papaya L., extracci\uf3n alcoh\uf3lica en dos pasos, Balls y Hoover, suero l\ue1cteo.
ABSTRACT
Latex is a thixotropic fluid contained in latiferous vessels under the exocarp of the papaya. Its content of proteolytic enzymes has made it a highly studied subject, in particular papain, which, even being among the minor constituents of these enzymes, it has the highest industrial use. In this investigation papain was purified from papaya latex and the effect of two drying conditions on enzyme activity was evaluated. The latex was extracted from the fruit\ub4s exocarp, dehydrated under two conditions (C), C1: 25\ubaC and 20 h and C2: 60\ubaC and 4 h, the dry yield was calculated and characterized. Subsequently, the papain was purified and quantified the enzymatic activity; then the purification factor (FP) was estimated and finally, the proteolytic activity was determined by evaluating the efficiency of removal of proteins from an industrial effluent. The dry latex in C1, with a yield of 1.38%, was characterized by having 52 \ub0 Brix, pH 6.26, humidity 8.50%, 39.48% ash; while in C2 yield 1.45%, 42.96 \ub0 Brix, pH 6.76, humidity 4.73%, 30.80% ash. The FP was 91.19-108.64%. Finally, the power of the enzyme was demonstrated by determining the efficiency of removal of the protein content of a dairy effluent. With the purified papain, an average protein removal of 60.03% was achieved.
Keywords: Carica papaya L., alcohol extraction in two steps, Balls and Hoover, dairy effluent. <br
CULTURA E INTERCULTURA EN LATINOAM\uc9RICA: PRESENCIA DE LOS INMIGRANTES CANARIOS EN EL ESTADO LARA, 1961-1981
Get PDFEl art\uedculo tiene como objetivo general reconstruir bajo una perspectiva te\uf3rico-metodol\uf3gica de la historia social el proceso cultural e intercultural en Latinoam\ue9rica, a partir de la presencia de los inmigrantes canarios en el estado Lara: 1961-1981. Para ello se analiza el proceso hist\uf3rico desde la realidad social, econ\uf3mica, pol\uedtica y cultural, con el prop\uf3sito de comprender la realidad intercultural generada a trav\ue9s de la recepci\uf3n, inserci\uf3n y adaptaci\uf3n canaria, para demostrar el desarrollo humano, econ\uf3mico y cultural dentro de la regi\uf3n larense, donde realza la actividad agr\uedcola y todo lo que la engloba. Metodol\uf3gicamente se fundamenta en la Historia Social y en el m\ue9todo hist\uf3rico, con el uso de fuentes primarias y secundarias. Se concluye la efectividad del sincretismo y la interculturalidad a partir de la construcci\uf3n de la cultura: agr\uedcola, de riego y hort\uedcola, donde prevalecen los valores humanos, sociales, religiosos, deportivos, econ\uf3micos, productivos y culturales.
Palabras clave: Cultura, Intercultura, Inmigrantes Canarios.
ABSTRACT
The aim of the research article is to reconstruct the cultural and intercultural process based on the presence of the Canary Islands in Latin America and the Lara State, as this entity is a representation of the Canarian immigration issue from 1961 to 1981. In view of this, the resulting methodology is taken of the historical science and the foundations of the French School of Annales, through the use of primary and secondary sources to apply the historical method, which starts from defining the area under study, the time scale, the construction of a source bank for contextualize the historical reality and understand the social and institutional structures during the process of cultural syncretism generated through the Canarian reception, insertion and adaptation. It concludes the participation and effectiveness in the Canarian insertion in the Venezuelan society, resulting in a sustainable human, economic and cultural development within the Larense region, where it enhances the agricultural, irrigation and horticultural culture, and human, social values, religious, sporting, economic, productive and cultural.
Keywords: Culture, Interculture, Immigrants Canaries.<br
EXPOSICI 3N "ARPEGIOS DE COLORES" EN HOMENAJE AL MAESTRO ALIRIO D\ucdAZ. 12 AL 26 DE JULIO DE 2018 GALER\ucdA RAFAEL MONASTERIOS DE LA UCLA
Get PDFOSTEOCONDROSIS EQUINA: UNA ENFERMEDAD CONTROVERTIDA CON ETIOLOG\ucdA MULTIFACTORIAL
Get PDFLa osteocondrosis (OC) es un desorden osteoarticular que afecta principalmente a humanos, cerdos, caballos y perros. Es una de las enfermedades articulares m\ue1s comunes de los caballos en crecimiento, perteneciendo al complejo de enfermedades ortop\ue9dicas del desarrollo. Se caracteriza por una alteraci\uf3n de la osificaci\uf3n endocondral que afecta al cart\uedlago de crecimiento y al hueso subcondral, y es considerada la fase primaria del da\uf1o al complejo articular-epifiseal. Su etiolog\ueda se reporta como multifactorial y los factores etiol\uf3gicos descritos con mayor frecuencia son la herencia, los desequilibrios diet\ue9ticos y endocrinos, el r\ue1pido crecimiento, el trauma y los defectos vasculares del cart\uedlago de crecimiento, pero en la actualidad permanece incompletamente entendida y existe gran controversia sobre la participaci\uf3n e interacci\uf3n de estos factores en la aparici\uf3n de la enfermedad. La osteocondrosis es una enfermedad que causa grandes p\ue9rdidas econ\uf3micas en la industria equina, representando un problema importante para el sector, de ah\ued el gran inter\ue9s en determinar su origen.
Palabras clave: equino, osteocondrosis, cart\uedlago de crecimiento, hueso subcondral, etiolog\ueda multifactorial.
ABSTRACT
Osteochondrosis (OC) is an osteoarticular disorder that mainly affects humans, pigs, horses and dogs. Is one of the most common joint diseases of growing horses, belonging to developmental orthopedic diseases complex. It is characterized by an alteration of the endochondral ossification that affects growth of cartilage and the subchondral bone, and is considered the primary phase of damage to joint-epiphyseal complex. Its etiology is reported to be multifactorial and etiological factors most often described are heredity, dietary and endocrine imbalances, rapid growth, trauma and vascular defects of the growth cartilage, but it is incompletely understood, and there is great controversy about the participation and interaction of these factors in appearance of the disease. Osteochondrosis is a disease that causes great economics losses in horse industry, representing an important problem for the sector, hence the great interest in determining its origin.
Key words: equine, osteochondrosis, growth cartilage, subchondral bone, multifactorial etiology. <br
ADAPTACI 3N PARCIAL DE LA EMPRESA VENEZOLANA EN UN ENTORNO DE REGULACIONES Y CONTROLES. PER\ucdODO: 2010-2015
Get PDFLa investigaci\uf3n planteada deduce las respuestas adaptativas de la empresa venezolana ante el prop\uf3sito gubernamental de suprimir la econom\ueda de mercado y afectar la propiedad privada. El uso de modelos es frecuente en el an\ue1lisis microecon\uf3mico, ellos permiten anticipar reacciones racionales de las unidades productivas, ante variaciones en las condiciones del mercado, sujetas al cumplimiento de ciertos supuestos. El comportamiento de la empresa ante una eventual supresi\uf3n del mercado, constituye una novedad. Una aproximaci\uf3n a su estudio se emprende tomando como punto de partida el modelo de la Competencia Perfecta (CP), luego se procede a levantar los supuestos b\ue1sicos, introduciendo restricciones que simulan situaciones reales acaecidas en el tercer lustro del presente siglo. Las respuestas son predecibles: ajustes en el nivel de producci\uf3n, en la composici\uf3n de la gama de productos a ofrecer, el n\ufamero de trabajadores, reducci\uf3n de los gastos en adquisici\uf3n de maquinaria y equipo (inversi\uf3n) y en mejoras tecnol\uf3gicas, con el fin de mantener operativas las plantas, y, en caso extremo, cese de operaciones. El principal hallazgo resulta parad\uf3jico: para sobrevivir, la empresa est\ue1 condenada a ser ineficiente en la asignaci\uf3n de los recursos.
Palabras clave: Adaptaci\uf3n empresarial, mercado, regulaci\uf3n, productividad.
ABSTRACT
The proposed research deduces the adaptive responses of the Venezuelan company to the governmental purpose of suppressing the market economy and affecting private property. The use of models is frequent in the microeconomic analysis, they allow to anticipate rational reactions of the productive units, due to variations in the market conditions, subject to the fulfillment of certain assumptions. The behavior of the company in the event of a possible suppression of the market, constitutes a novelty. An approach to their study is undertaken taking as a starting point the Perfect Competition model (PC), then proceeds to raise the basic assumptions, introducing restrictions that simulate real situations occurred in the third luster of the present century. The answers are predictable: adjustments in the level of production, in the composition of the range of products to be offered, the number of workers, reduction of expenses in acquisition of machinery and equipment (investment) and in technological improvements, in order to keep operative the plants and, in extreme cases, cease operations. The main finding is paradoxical: to survive, the company is doomed to be inefficient in the allocation of resources.
Key words: Business adaptation, market, regulation, productivity.
RESUMO
A pesquisa proposta deduz as respostas adaptativas da empresa venezuelana para o prop\uf3sito governamental de suprimir a economia de mercado e afetar a propriedade privada. O uso de modelos \ue9 freq\ufcente na an\ue1lise microecon\uf4mica, permitindo antecipar as rea\ue7\uf5es racionais das unidades produtivas, ante varia\ue7\uf5es nas condi\ue7\uf5es de mercado, sujeito ao cumprimento de certos pressupostos. O comportamento da empresa ante uma eventual supress\ue3o do mercado, constitui uma novidade. Uma abordagem para o seu estudo \ue9 realizada tomando como ponto de partida o modelo da Compet\ueancia Perfeita (PC), logo se procede a levantar os pressupostos b\ue1sicos, introduzindo restri\ue7\uf5es que simulam situa\ue7\uf5es reais ocorridas no terceiro quinquenio do s\ue9culo atual. As respostas s\ue3o previs\uedveis: ajustes no n\uedvel de produ\ue7\ue3o, na composi\ue7\ue3o da gama de produtos a serem oferecidos, no n\ufamero de trabalhadores, na redu\ue7\ue3o das despesas de aquisi\ue7\ue3o de m\ue1quinas e equipamentos (investimento) e em melhorias tecnol\uf3gicas, a fim de manter as instala\ue7\uf5es operacionais e, em casos extremos, cessar as opera\ue7\uf5es. O principal achado \ue9 paradoxal: para sobreviver, a empresa \ue9 condenada a ser ineficiente na aloca\ue7\ue3o de recursos.
Palavras chave: adapta\ue7\ue3o empresarial, mercado, regula\ue7\ue3o, produtividade. <br