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1
artículo
Support Vector Machines are extensively used to solve classification problems in Pattern Recognition. They deal with small errors in the training data using the concept of soft margin, that allowfor imperfect classification. However, if the training data have systematic errors or outliers such strategy is not robust resulting in bad generalization. In this paper we present a model for robust Support Vector Machine classification that can automatically ignore spurius data. We show then that the model can be solved using a high performance Mixed Integer Quadratic Programming solver and present preliminary numerical experiments using real world data that looks promissing.
2
artículo
Publicado 2020
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The aim of this article is to develop the most relevant strategy approaches and the approaches related to business models, and to demonstrate the close link existing between both concepts. The theoretical referents are Michael Porter, Henry Mintzberg, Kim, and Mauborgne, Osterwalder and Pigneur, with focus on the strategy proposed by Igor Ansoff. We analyze the sequencing of the use of the various strategy approaches and the business models approaches, and the impact on each other. We end up by answering the query: What comes first, the strategy or the business model?
3
artículo
Publicado 2020
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The aim of this article is to develop the most relevant strategy approaches and the approaches related to business models, and to demonstrate the close link existing between both concepts. The theoretical referents are Michael Porter, Henry Mintzberg, Kim, and Mauborgne, Osterwalder and Pigneur, with focus on the strategy proposed by Igor Ansoff. We analyze the sequencing of the use of the various strategy approaches and the business models approaches, and the impact on each other. We end up by answering the query: What comes first, the strategy or the business model?
4
artículo
Publicado 2020
Enlace
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The aim of this article is to develop the most relevant strategy approaches and the approaches related to business models, and to demonstrate the close link existing between both concepts. The theoretical referents are Michael Porter, Henry Mintzberg, Kim, and Mauborgne, Osterwalder and Pigneur, with focus on the strategy proposed by Igor Ansoff. We analyze the sequencing of the use of the various strategy approaches and the business models approaches, and the impact on each other. We end up by answering the query: What comes first, the strategy or the business model?
5
tesis de maestría
Publicado 2015
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Las enfermedades transmitidas por vectores son una preocupación mundial, ya que representan el 17% de todas las enfermedades infecciosas y más de 1 millón de muertes al año. En particular, el dengue y la malaria, transmitidos por mosquitos, son las enfermedades transmitidas por vectores más alarmantes porque la primera es la enfermedad viral transmitida por mosquitos que tuvo la mayor incidencia de crecimiento en los últimos 50 años (30 veces) y la segunda tiene la mayor incidencia de mortalidad con una estimación de 627 mil muertes en 2012. Predecir la incidencia de estas enfermedades es un paso importante para mejorar los programas de control a fin de prevenir brotes con una distribución eficiente de logística y recursos humanos a las zonas afectadas dentro de un plazo razonable; sin embargo, los factores de riesgo que determinaron la incidencia no se comprenden completamente...
6
artículo
Publicado 2022
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Remote sensing with large-scale satellite images for precision studies in grasslands has spatial and spectral resolution limitations. Against this, using spectral signs and vegetation indices obtained with microsensors transported by unmanned aerial vehicles (UAV) constitutes a more accurate alternative for biomass estimation. In the fieldwork, images were acquired with microsensors, and fixed transects of 100 m were used where vegetation samples were collected. The photographs acquired with the UAV were processed in Pix 4D, Arc Gis, and algorithms elaborated in R programming language. The biomass estimation was carried out with Multiple Linear Regression, Vector Support Machine, and Random (Forest Random) models. The Random model showed a Kappa coefficient of 0.94 in the training set and 0.901 in the test set (R2 = 0.482). The Random Forest model predicted 3 g/pixel of MV for Puna grass...
7
artículo
Since it's invention, the Field Orientation Vector Control has been usefully for controlling Induction Machines (IM) for high dynamic performance. Among Field Orientation Vector Control methods. one uses leakage rotor referential flux, in order to reduce non linear model equations of IM to a system based on dq axes model, similar to DC motor. On this article, it is show fundamentals of this Vector Control method as well as a method for calibrating Proportional Integral controllers in order to archive a high dynamic performance IM control.
8
tesis de grado
Publicado 2025
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The purpose of the study using 386 monthly data from the period 1992:11 to 2024:12 was to compare the forecasting capacity of two multivariate models: the Vector Autoregressive Model (VAR) and the Vector Error Correction Model (VECM). According to the indicators Root Mean Squared Error (RSME) and the average of the errors measured as the percentage of the difference (in absolute value) between the observed and predicted value (Mean Absolute Percentage Error – MAPE), the VECM model reported better performance, since the RMSE was 174 million dollars lower than that of the VAR, which showed 400 million. The MAPE was 50.44% compared to the VAR MAPE of 263%. The Granger causality test shows that there is causality between the study variables except for exports and the multilateral real exchange rate, which do not explain the inflation of trading partners, which makes economic sense.
9
tesis de maestría
Publicado 2025
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Universidad Nacional Agraria La Molina. Escuela de Posgrado. Maestría en Estadística Aplicada
10
tesis de grado
Publicado 2025
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Un asunto en salud pública de importancia en el Perú es el de la epilepsia; enfermedad que, entre el carácter en esencia, imprevisible de sus manifestaciones - las cuales son conocidas como crisis epilépticas - y los bajos índices de diagnóstico y de tratamiento, repercute en la calidad de vida de las personas que la padecen; siendo esto particularmente notable en quienes sufren de un tipo particular de crisis epilépticas denominadas tónico-clónicas, las cuales se caracterizan por la aparición de una actividad motora descontrolada precedida por la pérdida de conciencia constituyendo un motivo frecuente de atención en los servicios de emergencia y que conlleva a implicancias tanto en el ámbito sanitario como en el económico y social. Ante esta problemática en el presente trabajo se desarrolla un modelo que permite detectar estos tipos de crisis consideradas de alto riesgo, ...
11
artículo
Publicado 2012
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Fish is the cheapest animal protein source in Nigeria, and dry fish in particular has the potential to solve the pervasive protein shortage problem owing to its relative affordability compared with fresh fish. Boosting dry fish consumption will entail retail price reduction which is achievable only if the market for dry fish operates efficiently. This study, after testing and correcting price series for non-stationarity, modelled marketing efficiency in 66 pairs of spatially separated markets. The unit root test was used to reveal the order of econometric integration of the price series. All price series showed non-stationarity at their levels (P<0.05), but on first-differencing, they all rejected the null hypothesis of non-stationarity. This confirmed that they were generated by the same stochastic processes and, thus, capable of exhibiting long-run spatial equilibrium. The vector auto-...
12
tesis de maestría
Publicado 2018
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En la actualidad, el pronóstico de datos espacio - temporales ha sido de especial interés para investigadores académicos y profesionales de la industria por su gran utilidad para planificar y desarrollar medidas de contingencia contra futuras condiciones adversas. En este trabajo se pro¬pone una metodología para el pronóstico de mapas tipo ráster. Siguiendo una metodología de resumir-predecir-y-reconstruir, el método sugiere reducir la dimensionalidad de los datos usando un análisis de componentes principales para luego realizar pronósticos individuales sobre las com¬ponentes o auto vectores más significativos. Finalmente, un algoritmo recursivo, aplicado sobre la reconstrucción inversa espectral de los pronósticos individuales, brinda el pronóstico final de los mapas. La metodología propuesta da lugar a tres modelos: el modelo espacial de componentes princi¬pales (ECP)...
13
artículo
Publicado 2025
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The early prediction of corporate bankruptcy is a key challenge for economic stability and risk management in emerging markets. This study explores the application of various Machine Learning techniques to anticipate the probability of insolvency in companies operating in the Peruvian market. The main objective is to compare the predictive capacity of both classical and modern models, including multiple discriminant analysis, logistic regression, Support Vector Machines, Random Forest, Bagging, Boosting, and neural networks, using accounting and financial information. The methodology involved building a database of financial series from Peruvian firms, normalizing ratios, splitting the data into training and testing sets, and evaluating performance through widely used classification metrics such as accuracy, recall, F1 score, Type I and II errors, and AUC. The results show that ensemble-...
14
tesis de maestría
Publicado 2018
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Nowadays spatio-temporal forecasting has been drawing more and more attention from academia researchers and industrial practitioners for its great utility to plan and develop contingency measures against future adverse conditions. In this thesis, a methodology to forecast maps in spatio- temporal raster datasets is proposed. Following a summarize-predict-and-rebuild methodology, it 1) first suggests a reduction in the dimensionality of data using a principal component analysis, then 2) individual forecasts on the most significant components or eigenvectors are calculated using a neural networks - wavelet decomposition model. Finally, 3) a recursive algorithm, applied on the spectral inverse reconstruction of the individual forecasts, provides the final forecast maps. The devised methodology led to three models according: the spatial principal component anal¬ysis (SPCA) model, the tempor...
15
artículo
Purpose. This article examines whether deviations from fundamental value or closed-end country fund's discounts or premiums forecast future share price returns or net asset returns. Design/methodology/approach. The main empirical (econometric) tool is a vector autoregressive (VAR) model. The authors model share price returns and net asset returns as a function of their lagged values, the discounts or premiums, and a control variable for local market returns. The authors also conduct Dickey Fuller and Granger causality tests as well as impulse response functions. Findings. It was found that deviations from fundamental value do predict share price returns. This predictability is contrary to weak-form market efficiency. Premiums or discounts predict net asset returns but weakly. Originality/value. The findings point to the idea that the closed-end fund market is somewhat predictable and ine...
16
artículo
This paper presents an optimal control strategy for the Zika virus disease with sexual transmission. A mathematical model for the transmission of the Zika virus is considered with three preventive measures as control, namely: the prevention of the sexual contagion with the use of condoms and the orientation in the transmission of Zika in the homosexual and heterosexual relations, the campaigns against vectors and the protection of the society regarding the contagion by mosquito bites. We examine the implementation of various combinations of the control strategies in order to determine the most cost-effective one. The necessary conditions for the optimal controls are determined using Pontryaguin’s maximum principle and the optimality problem is solved using Runge-Kutta fourth order scheme. Based on the computational results, we conclude that the most efficient control strategy is when i...
17
artículo
This paper presents an optimal control strategy for the Zika virus disease with sexual transmission. A mathematical model for the transmission of the Zika virus is considered with three preventive measures as control, namely: the prevention of the sexual contagion with the use of condoms and the orientation in the transmission of Zika in the homosexual and heterosexual relations, the campaigns against vectors and the protection of the society regarding the contagion by mosquito bites. We examine the implementation of various combinations of the control strategies in order to determine the most cost-effective one. The necessary conditions for the optimal controls are determined using Pontryaguin’s maximum principle and the optimality problem is solved using Runge-Kutta fourth order scheme. Based on the computational results, we conclude that the most efficient control strategy is when i...
18
artículo
Publicado 2020
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Zika virus spreads to people primarily through the bite of an infected Aedes aegypti species mosquito. But it Zika can also be passed through sex from an infected to his or her sex partners and it can be spread from a pregnant woman to her fetus. Zika continues to spreading geographically to areas where competent vectors are present. Although a decline in cases of Zika virus infection has been reported in some countries, or in some parts of countries, vigilance needs to remain high. In this work, we present two mathematical models for the Zika diffusion by using (1) ordinary differential equations with exposed state and, (2) ordinary differential equations with delay (discrete), which is the time it takes mosquitoes to develop the virus. We make a comparison between the two modeling variants. Computational simulations is performed for Santa Ana, which is that is prone to develop the epid...
19
artículo
Publicado 2020
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Zika virus spreads to people primarily through the bite of an infected Aedes aegypti species mosquito. But it Zika can also be passed through sex from an infected to his or her sex partners and it can be spread from a pregnant woman to her fetus. Zika continues to spreading geographically to areas where competent vectors are present. Although a decline in cases of Zika virus infection has been reported in some countries, or in some parts of countries, vigilance needs to remain high. In this work, we present two mathematical models for the Zika diffusion by using (1) ordinary differential equations with exposed state and, (2) ordinary differential equations with delay (discrete), which is the time it takes mosquitoes to develop the virus. We make a comparison between the two modeling variants. Computational simulations is performed for Santa Ana, which is that is prone to develop the epid...
20
artículo
Publicado 2019
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Zika virus spreads to people primarily through the bite of an infected Aedes aegypti species mosquito. But it Zika can also be passed through sex from an infected to his or her sex partners and it can be spread from a pregnant woman to her fetus. Zika continues to spreading geographically to areas where competent vectors are present. Although a decline in cases of Zika virus infection has been reported in some countries, or in some parts of countries, vigilance needs to remain high. In this work, we propose a mathematical model that uses diffusion-advection equations to study the impact of the Zika epidemic. We present a numerical scheme linking finite elements (FEM) with finite differences to solve the model. The computer simulations are performed for Paramaribo and Santa Ana that have different demographic characteristics and allow us to extend the study to other regions.
