56 research outputs found
Corrosion Resistance of GMAW Duplex Stainless Steels Welds
No full textThe hydrocarbon industry constantly requires a better understanding of stainless-steel welding metallurgy. Despite the fact that gas metal arc welding (GMAW) is one of the most commonly employed welding processes in the petrochemical industry, the process is characterized by the presence of a high number of variables to control in order to obtain components that are dimensionally repeatable and satisfy the functional requirements. In particular, corrosion is still a phenomenon that highly affects the performance of the exposed materials, and special attention must be paid when welding is applied. In this study, the real operating conditions of petrochemical industry were reproduced through an accelerated test in a corrosion reactor at 70 °C for 600 h, exposing robotic GMAW samples free of defects with suitable geometry. The results show that, even if duplex stainless steels are characterized for being more corrosion resistant than other stainless steels, under these conditions it was possible to identify microstructural damage. In detail was found that the corrosion properties were strongly related to the heat input during welding and that the best corrosion properties can be obtained with the higher heat input
Recent Advances in Additive Manufacturing of Soft Magnetic Materials: A Review
No full textAdditive manufacturing (AM) is an attractive set of processes that are being employed lately to process specific materials used in the fabrication of electrical machine components. This is because AM allows for the preservation or enhancement of their magnetic properties, which may be degraded or limited when manufactured using other traditional processes. Soft magnetic materials (SMMs), such as Fe–Si, Fe–Ni, Fe–Co, and soft magnetic composites (SMCs), are suitable materials for electrical machine additive manufacturing components due to their magnetic, thermal, mechanical, and electrical properties. In addition to these, it has been observed in the literature that other alloys, such as soft ferrites, are difficult to process due to their low magnetization and brittleness. However, thanks to additive manufacturing, it is possible to leverage their high electrical resistivity to make them alternative candidates for applications in electrical machine components. It is important to highlight the significant progress in the field of materials science, which has enabled the development of novel materials such as high-entropy alloys (HEAs). These alloys, due to their complex chemical composition, can exhibit soft magnetic properties. The aim of the present work is to provide a critical review of the state-of-the-art SMMs manufactured through different AM technologies. This review covers the influence of these technologies on microstructural changes, mechanical strengths, post-processing, and magnetic parameters such as saturation magnetization (MS), coercivity (HC), remanence (Br), relative permeability (Mr), electrical resistivity (r), and thermal conductivity (k)
Análise sobre a obra Latifúndio, Escravidão e Dependência Econômica de Ramiro Guerra
No full textThis work aims to analyze the work of Ramiro Guerra (Latifundia, slavery and economic dependence), one of his main works dealing with the region of Barbados located in the Lesser Antilles in Central America. Thus, the analysis shows how Ramiro Guerra demystifies a whole theory regarding the substitution of the work of the small owner for the cheap labor of the slave. The same author emphasizes that this substitution was not due to a question of races or of climate or even of the superiority of the human will. But due to a purely social and economic cause: the destruction of small property by the sugar estates and the consequent emigration of a social class that would be expelled in a "voluntary" way due to lack of work. Thus, according to Guerra's analysis, the analysis emphasizes that it was not the Antillean climate that drove out the white servants but the capitalist sugar company that would settle in the region, annihilating the small property and eliminating the independent cultivator and converting the robust communities with their own lives in mere low-wage workshops, all for the benefit of metropolises. And also the consequences of this sugar trade in Cuba with the same consequences of the destruction of small-scale agriculture.
JEL Classification: Q1.Este trabalho tem como objetivo analisar a obra de Ramiro Guerra (Latifúndio, escravidão e dependência econômica), uma das suas principais obras que trata da região de Barbados localizada nas Pequenas Antilhas na América Central. Assim, a análise mostra como Ramiro Guerra desmistifica toda uma teoria em relação à substituição do trabalho do pequeno proprietário pela mão de obra barata do escravo. O mesmo autor ressalta que essa substituição não foi devido a uma questão de raças ou de clima ou até mesmo da superioridade da vontade humana. Mas sim, devido a uma causa puramente social e econômica: a destruição da pequena propriedade pelo latifúndio açucareiro e pela conseguinte emigração de uma classe social que seria expulsa de forma “voluntária” devido à falta de trabalho. Dessa forma, a análise de acordo com o pensamento de Guerra, enfatiza que não foi o clima antilhano que expulsou os servos brancos, mas sim a empresa açucareira capitalista que se instalaria na região, aniquilando a pequena propriedade e eliminando o cultivador independente e convertendo as comunidades robustas com vidas próprias em meras oficinas de trabalho com salários baixos, tudo em prol das metrópoles. E também as consequências desse comércio açucareiro em Cuba trazendo as mesmas consequências de destruição da pequena agricultura.
Classificação JEL: Q1
Diseño de un modelo de gestión financiero y contable aplicado a la empresa Megahimersa Cía. Ltda., ubicada en el norte de la ciudad de Quito.
No full textEn la actualidad la empresa Megahimersa Cía. Ltda., tiene dificultades para definir los procesos contables así como la gestión financiera de sus actividades, dichas dificultades se debe a que no existe un modelo de gestión preestablecido que ayude al correcto desenvolvimiento de la gestión financiera en la misma.
La empresa al no poseer un modelo de gestión financiero y contable, puede tener dificultades en la realización de sus actividades, lo que conlleva al entorpecimiento de sus procesos y la mala utilización de recursos tanto humanos como financieros, irrecuperables para la empresa, conllevando en un futuro cercano a no contar con un margen de utilidad aceptable.
En base a lo antes mencionado, se ha diseñado un Modelo de Gestión Financiera para la empresa, con el fin de tener una guía para conocer su situación financiera a través del análisis de los estados financieros y evaluar el desempeño económico real, apoyando a la administración para la buena toma de decisiones frente a las circunstancias de crecimiento operacional y estratégico con el correcto uso de los recursos, de tal manera que mejore la eficiencia, eficacia y efectividad de sus actividades y logre mantenerse dentro de un rango razonable en el mercado nacional.Currently the company Megahimersa Cia. Ltda. has difficulty defining accounting processes and financial management of their activities, these difficulties is that there is no preset management model that helps the smooth development of the financial management in the same.
The company in the absence of a model of a financial and accounting management, may have difficulty in carrying out their activities, leading to some obstructions of their processes and the misuse of resources both human and financial, unrecoverable for the company, leading a near future will not have an acceptable profit margin.
Taking into account the above, it has been designed a financial management model for the company, in order to have a guide to know its financial situation through the analysis of financial statements and assess the actual economic performance, supporting management for good decision making dealing with the circumstances of operational and strategic growth with the proper use of resources, so as to improve the effectiveness and efficiency of this activities and achieve staying within a reasonable range at local level
Aplicación de la gestión de almacén para optimizar los costos logísticos en la empresa Plaza Victoria Trujillo 2022
No full textLa presente investigación titulada “Aplicación de gestión de almacén para
optimizar costos logísticos en la empresa Plaza Victoria Trujillo 2022” con una
metodología aplicada, pre experimental. Esta investigación tuvo como objetivo
principal optimizar los costos logísticos en la empresa. Para el primer objetivo
específico se aplicó como instrumento la entrevista, la clasificación ABC y
diagrama Ishikawa en el almacén. Acto seguido, en el segundo objetivo
específico se elaboró un control de merma para ver cuáles son los insumos
principales que más se dañan y los motivos de estas pérdidas, un estudio de
tiempos para disminuir los costos de despacho e inventariar la rotación para
disminuir el costo improductivo. Por consiguiente, para el tercer objetivo se
procedió a implementar el layout y capacitaciones para mejorar el orden y los
espacios, creación de diagramas de recorrido. Y finalmente como cuarto
objetivo se procedió a evaluar los cálculos de los costos logísticos después
que se implementos las mejoras a la empresa demostrando así logrando
reducir un 62% de los costos logísticos de la empresa Plaza Victoria Trujillo
The Vanadium Micro-Alloying Effect on the Microstructure of HSLA Steel Welded Joints by GMAW
No full textStructural applications that use High-Strength Low-Alloy (HSLA) steels require detailed microstructural analysis to manufacture welded components that combine strength and weldability. The balance of these properties depends on both the chemical composition and the welding parameters. Moreover, in multi-pass welds, thermal cycling results in a complex Heat-Affected Zone (HAZ), characterized by sub-regions with a multitude of microstructural constituents, including brittle phases. This study investigates the influence of Vanadium addition on the microstructure and performance of the HAZ. Multi-pass welded joints were manufactured on 15 mm thick S355 steels with different Vanadium contents using a robotic GMAW process. A steel variant containing both Vanadium and Niobium was also considered, and the results were compared to those of standard S355 steel. Moving through the different sub-regions of the welded joints, the results show a heterogeneous microstructure characterized by ferrite, bainite and martensite/austenite (M/A) islands. The presence of Vanadium reduces carbon solubility during the phase transformations involved in the welding process. This results in the formation of very fine (average size 11 ± 4 nm) and dispersed precipitates, as well as a lower percentage of the brittle M/A phase, in the variant with a high Vanadium content (0.1 wt.%), compared to the standard S355 steel. Despite the presence of the brittle phase, the micro-alloyed variants exhibit strengthening without loss of ductility. The combined presence of both hard and soft phases in the HAZ provides stress-damping behavior, which, together with the very fine precipitates, promises improved resistance to crack propagation under different loading conditions
Desarrollo de un software para procesamiento y corrección de registros, y generación de espectros de respuesta sísmica
No full textEl presente proyecto técnico se basa en el Desarrollo de un Software para Procesamiento y Corrección de Registros, y Generación de Espectros de Respuesta Sísmica.
Se desarrolló el software a través de la herramienta computacional Matlab, entre sus principales funciones tenemos el cálculo con el uso de matrices, la implementación de algoritmos y la creación de interfaces de usuario.
Se empezó realizando la corrección de los registros, primero se realizó la corrección de línea base por medio del método de Berg y Housner el cual es un método clásico que da buenos resultados. La segunda corrección que se realizó es la corrección del ruido presente en la señal a través de los distintos filtros.
Posteriormente se obtuvieron los espectros de respuesta de aceleración, velocidad y desplazamiento con base en métodos en el dominio del tiempo y de la frecuencia, cuyos métodos fueron el de Newmark, Integral de Duhamel y la Transformada de Fourier.
Una vez obtenido los resultados tanto de las correcciones como de los espectros de respuesta de un registro se procedieron a realizar las verificaciones con el programa Prism, de la Universidad INHA.
Una vez comprobados los resultados, realizamos una comparación entre los tres métodos para saber la similitud entre ellos, se verifico que entre el método de Newmark y la Integral de Duhamel hay mayor similitud que, con respecto al método de la Transformada de Fourier, debido a que cada método sigue diferentes caminos para llegar a resultados similares.This technical project is based on the Development of a Software for Processing and Correction of Records, and Generation of Seismic Response Spectra.
The software was developed through the Matlab computational tool, among its main functions we have the calculation with the use of matrices, the implementation of algorithms and the creation of user interfaces.
The correction of the records began, first the baseline correction was carried out by means of the Berg and Housner method, which is a classic method that gives good results. The second correction that was made is the correction of the noise present in the signal through the different filters.
Subsequently, the response spectra of acceleration, velocity and displacement were obtained based on methods in the time and frequency domain, whose methods were the Newmark, the Duhamel integral and the Fourier transform.
Once the results of both the corrections and the response spectra of a record had been obtained, the verifications were carried out with the Prism program, from INHA University.
Once the results were verified, we made a comparison between the three methods to know the similarity between them, it was verified that between the Newmark method and the Duhamel Integral there is greater similarity, than with respect to the Fourier transform method, due to that each method follows different paths to reach similar results
Evaluating Hamming Distance as a CRC-based Side-channel Detection Measure in Wi-Fi Networks
No full textAbstractWireless technology has become a main player in communication through its desirable mobility characteristic. However, like many technologies, there are ways that it can be exploited. One of these ways is through side-channel communication, whereby secret messages are passed along by the purposeful corruption of frames. These side channels can be established by intentionally corrupting the Frame Check Sequence (FCS) field by using a Cyclic Redundancy Check (CRC) polynomial that is different from the standard CRC polynomial. Malicious nodes can exploit the fact that normal unsuspecting nodes will drop these frames since they appear as naturally corrupted frames. This paper presents a CRC Hamming distance metric as a feature for the detection of this type of side-channel communication. We previously proposed the use of Hamming distance as a metric to compare CRC values that are generated by different CRC polynomials. The hypothesis is that the mean Hamming distance between two CRC values generated by two different CRC polynomials would be significantly far apart than the mean Hamming distance of a CRC value of a frame that was naturally corrupted but was generated by the same CRC polynomial. Previously, to test that hypothesis, we used F-Scores on real data experiments under varying noisy conditions and side-channel throughput to show that there is a consistent and significant difference between the mean Hamming values of naturally corrupted frames to those that use the Koopman polynomial to calculate the CRC for side-channel communications. In the present work we evaluate the Hamming distance using Perceptron Learning and the Pocket Algorithm to classify packets as side-channel or otherwise
Evaluating Hamming Distance as a Metric for the Detection of CRC-based Side-channel Communications in MANETs
No full textAbstractSide-channel communication is a form of traffic in which malicious parties communicate secretly over a wireless network. This is often established through the modification of Ethernet frame header fields, such as the Frame Check Sequence (FCS). The FCS is responsible for determining whether or not a frame has been corrupted in transmission, and contains a value calculated through the use of a predetermined polynomial. A malicious party may send messages that appear as nothing more than naturally corrupted noise on a network to those who are not the intended recipient. We use a metric known as Hamming distance in an attempt to differentiate purposely corrupted frames from naturally corrupted ones. In theory, it should be possible to recognize purposely corrupted frames based on how high this Hamming distance value is, as it signifies how many bits are different between the expected and the received FCS values. It is hypothesized that a range of threshold values based off of this metric exist, which may allow for the detection of side-channel communication across all scenarios. We ran an experiment with human subjects in a foot platoon formation and analyzed the data using a support vector machine. Our results show promise on the use of Hamming distance for side-channel detection in MANETs
Intervenciones de enfermería en cáncer de testículo
No full textEl cáncer testicular (CT) se caracteriza por el crecimiento de células malignas en los testículos y es más frecuente en hombres jóvenes, entre los 15 y 40 años. Objetivo: Identificar las intervenciones de enfermería que se emplean en pacientes con cáncer testicular. Metodología: Se llevó a cabo una revisión bibliográfica de estudios publicados desde 2019 en los idiomas inglés, español y portugués. Se consultaron bases de datos científicas como PubMed, Scopus, Web of Science, SciELO, ProQuest y Redalyc, utilizando palabras claves DeCS: "cáncer testicular", "incidencia", "factores asociados", "complicaciones", "abordaje terapéutico" y " atención de enfermería", conjuntamente con el operador booleano AND, se crearon las estrategias de búsqueda. Resultados: En EE. UU. se reportaron 9.470 casos de cáncer testicular, mientras que en Medio Oriente y el Norte de África se identificaron aproximadamente 8.500 casos. Los factores de riesgo incluyen antecedentes familiares, consumo de alcohol, criptorquidia, además, se observó una mayor incidencia en individuos de ascendencia africana. Dentro de las complicaciones más comunes destacan la metástasis a más de la ansiedad y la depresión, derivadas de los cambios físicos, emocionales y el tratamiento, que puede incluir orquiectomía, quimioterapia y radioterapia. El personal de enfermería desempeña un papel fundamental en el bienestar del paciente, proporcionando apoyo físico y emocional antes, durante y después del tratamiento. Conclusión: Aunque el cáncer testicular es poco frecuente, tiene un impacto significativo en la calidad de vida del paciente. Es esencial que los cuidados de enfermería sean multidisciplinarios para mejorar la vida del paciente y prevenir complicaciones asociadas.
Palabras claves
Atención de enfermería, Neoplasia Testicular, Incidencia, Terapéutica, Factores de riesgo.Testicular cancer (TC) is characterized by the growth of malignant cells in the testicles and is more common in young men between the ages of 15 and 40. Objective: To identify the nursing interventions employed in patients with testicular cancer. Methodology: A literature review of studies published since 2019 in English, Spanish, and Portuguese was conducted. Scientific databases such as PubMed, Scopus, Web of Science, SciELO, ProQuest, and Redalyc were consulted, using DeCS keywords: "testicular cancer," "incidence," "associated factors," "complications," "therapeutic approach," and "nursing care," along with the boolean operator AND to create search strategies. Results: In the U.S., 9,470 cases of testicular cancer were reported, while approximately 8,500 cases were identified in the Middle East and North Africa. Risk factors include family history, alcohol consumption, cryptorchidism, and a higher incidence was observed in individuals of African descent. Among the most common complications are metastasis, as well as anxiety and depression resulting from physical and emotional changes and treatment, which may include orchiectomy, chemotherapy, and radiotherapy. Nursing staff play a fundamental role in the patient's well-being, providing physical and emotional support before, during, and after treatment. Conclusion: Although testicular cancer is rare, it has a significant impact on the patient's quality of life. Nursing care must be multidisciplinary to improve the patient's life and prevent associated complications.
Keywords
Nursing care, Testicular Neoplasm, Incidence, Therapeutics, Risk factors.Tesi
- …
