676 research outputs found

    Quantification and prediction of the concentration of different dilutions of Lambda Cyhalothrin through colorimetry and neural networks

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    The Lambda Cyhalothrin is an insecticide of broad spectrum used in agriculture, to reduce the loss in crops, due to the attack of some pests. This compound has the presence of the radicals chlorine, fluorine and cyano, which can cause serious effects on human health when are ingested. Because of this, exist the need of develop non - destructive methods, capable of determining the concentration of the pesticide in farming, for eradicate the presence of this substance on the fruit used as food. To achieve this, commercial Lambda Cyhalothrin and distilled water were used, to obtain the recommended dilutions for the treatment of various pests in agriculture. The samples were analyzed through colorimetry, obtaining the characteristic color spaces for the pesticide, with a correlation of 0.92 for the parameters "a" and "b", and 0.98 for the parameter "L". The Cab chroma and Hue angle were determined in 9.72 and 275° respectively for the pure compound. in the dilution, the value of Hue angle decreases until 220°. Through neural networks in Matlab, the relationship between the reflection spectrum of the dilutions with the concentration thereof was established. Estimating a prediction in the accuracy higher than 0.98 in the coefficient of determination

    Efecto termosifón en sistemas con colectores cilíndrico parabólicos

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    Thermosyphon effect is a natural convection phenomenon that gives a fluid the possibility to circulate inside a closed loop without any external pump sources. Numerical and simulation analysis are driven to check the behavior of thermosyphon effect in different heat transfer fluids, using parabolic trough collectors as the heating section of the system. Also, convection and radiation losses are considered. Simulations show variations in fluids density caused by different temperature and specific heat values, altering the velocity of the fluid inside the system with the same initial conditions.El efecto termosifón es un fenómeno de convección natural que le da a un fluido la posibilidad de circular dentro de un circuito cerrado sin ninguna fuente de bomba externa. En el presente artículo de investigación se realiza el análisis numérico y de simulación para verificar el comportamiento del efecto termosifón en diferentes fluidos de transferencia de calor, utilizando colectores cilindroparabólicos como sección de calentamiento del sistema. Además, se consideran las pérdidas por convección y radiación. Se obtiene que las simulaciones muestran variaciones en la densidad de los fluidos causadas por diferentes temperaturas y valores de calor específicos, alterando la velocidad del fluido dentro del sistema bajo las mismas condiciones iniciales

    Algorithm of temperature prediction for 2017 year in the municipality of Cajicá

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    Los factores climáticos son determinantes para el ser humano, porque con el paso de los años muestran una mayor variación y afectan drásticamente el comportamiento del medio ambiente. Uno de los factores más importantes es la temperatura, que se analiza constantemente en la agricultura, para predecir si el clima será favorable en todo tipo de cultivos, y si las condiciones no son adecuadas.Climatic factors are decisive for human being, because with the passing of the years they show greater variation and drastically affect the behavior of the environment. One of the most important factors is the temperature, which is constantly analyzed in agriculture, to predict if the weather will be favorable in all types of crops, and if the conditions are not adequate.Pregrad

    Revisión de las Tecnologías y Aplicaciones del Habla Sub-vocal

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    This paper presents a review of the main applicative and methodological approaches that have been developed in recent years for sub-vocal speech or silent language. The sub-vocal speech can be defined as the identification and characterization of bioelectric signals that control the vocal tract, when is not produced sound production by the caller. The first section makes a deep review of methods for detecting silent language. In the second part are evaluated the technologies implemented in recent years, followed by a review of the main applications of this type of speech and finally present a broad comparison between jobs that have been developed in industry and academic applications.Este trabajo presenta una revisión de estado de las principales temáticas aplicativas y metodológicas del habla sub-vocal que se han venido desarrollando en los últimos años. La primera sección hace una honda revisión de los métodos de detección del lenguaje silencioso. En la segunda parte se evalúan las tecnologías implementadas en los últimos años, seguido de un análisis en las principales aplicaciones de este tipo de lenguaje y finalmente presentado una amplia comparación entre los trabajos que se han hecho en industria y academia utilizando este tipo de desarrollos

    Sistemas de soporte de decisiones (SSD) aplicados a la formulación de políticas públicas agrarias

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    Context: The process of formulating agricultural public policies is very complex due to the large number of variables involved in the process. That is why the development of decision support systems (DSS) help to improve this process. The article reviews the developments that have been made regarding the subject. Method: The method was to conduct a bibliographic review in several scientific databases, looking for developments of DSS systems applied to the process of formulating agricultural policies. When determining which DSS systems have been developed, a qualitative and descriptive analysis of the systems was carried out.Contexto: El proceso de formulación de políticas públicas agrarias es muy complejo por la gran cantidad de variables que intervienen en el proceso. Por eso el desarrollo de sistemas de soporte de decisiones (SSD) ayudan a mejorar dicho proceso. El artículo revisa los desarrollo que se han realizado con respecto al tema. Método: El método fue realizar una revisión bibliográfica en varias bases de datos científicas, buscando desarrollos de sistemas SSD aplicados al proceso de formulación de políticas agrarias. Al determinar cuales sistemas SSD se han desarrollado, se procedió a realizar un análisis cualitativo y también descriptivo de los sistemas.  Resultados: Se encontraron 30 sistemas SSD aplicados a la formulación de políticas agrarias, donde la mayoría están enfocados al proceso de producción agrícola y su relación con el medio ambiente. Conclusiones: La más relevante es la necesidad de generar sistemas SSD que determinen posibles comportamientos futuros de los interesados, al desarrollar potenciales políticas agrarias. Ajustadas a las características propias de los países ubicados en la zona tropical

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

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    Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

    Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

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    The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

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    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV
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