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1. Estudio y modelación matemática del cambio metabólico de las bacterias responsables de la eliminación biológica de fósforo en el tratamiento de aguas residuales

  • ACEVEDO JUÁREZ, BRENDA
Subjects
PAO, GAO, EBPR, SBR, Fósforo, Fosfatos, Polifosfatos, Glucógeno, PHA, VFA, Metabolismo, Modelo metabólico, Cambio metabólico, Recuperación de fósoro, PAO Tipo I, PAO Tipo II, Corto plazo, Largo plazo, Estequiometría, Cinética, Monod, and TECNOLOGIA DEL MEDIO AMBIENTE
Abstract
[EN] Phosphorus is very important in life because it plays an essential role in biological processes. The main use of phosphorus is in the fertilizer industry in the form of phosphates. These phosphates come mainly from phosphate rocks which might be exhausted in 50-100 years. The overexploitation of phosphate rocks has resulted in decreased quality of reserves, and it has raised the cost of extraction, processing and shipping. Moreover, phosphorus coming from wastewater, phosphate rock dissolution, and soil with an excessive supply of fertilizer, is deposited on the surface water bodies causing a serious pollution problem called eutrophication. One of the systems most used to reduced phosphorus levels in the wastewater is the enhanced biological phosphorus removal (EBPR). This process involves capturing biologically, alternating between anaerobic oxic/anoxic conditions, the wastewater phosphorus through the phosphorus accumulating organisms (PAOs). However, one of the main problems of this process is that the glycogen accumulating organisms (GAOs) compete with PAOs for volatile fatty acids (VFA). Even though there have been many studies on the factors affecting competition between PAOs and GAOs, there are still many unanswered questions regarding the metabolism of PAOs when they lack energy reserves in the form of intracellular polyphosphates (poly-P) and its effect on the population dynamics of PAOs and GAOs in an activated sludge system. Therefore, the main goal of this dissertation is to study short- and long-term the metabolic behavior of the PAOs to different levels of poly-P; to analyze the population dynamics of microorganisms involved in the process EBPR; to model mathematically that metabolic behavior; and finally, to evaluate the possible recovery of phosphorus by extracting poly-P present in the PAOs. In the short- and long-term study was observed a metabolic shift correlates with the content in poly-P so that under low contents of poly-P the PAOs are able to behave as GAOs but without a significant development of the GAO population. Although, in both studies was observed the same metabolic behavior, from the microbiological point of view were observed some differences. In the short-term, the PAO Type II clearly showed the metabolic shift, while long-term were the PAO Type I. From the experiments performed, necessary expressions (stoichiometric and kinetic) were developed to include new behaviors observed (metabolic rate) in metabolic models existing today. Monod type expressions were developed and implemented on the model of the PAOs to represent the change between the typical stoichiometric parameters of PAO and GAO metabolism. The model was calibrated and validated showing the ability to correctly represent the metabolic change of PAOs under low concentrations of poly-P. When was observed that with low concentrations of poly-P the PAOs have the ability to change its metabolism, without the process was deteriorated by the development of the GAO population, two operating strategies were evaluated to obtain a stream rich in phosphorus to allow later retrieval. The strategies studied differed in the level of extraction of the poly-P from PAOs. In the first strategy, it was extracted less than 40 % of poly-P, while the second strategy, it came to extract more than 90 % of poly-P. The second strategy showed a higher extraction efficiency, achieving recover up to 81 % of the phosphorus present in the wastewater. As a result, of work performed four articles were generated, three of them published in journals of particular importance (2 in the journal Water Research and 1 in the journal Chemical Engineering Journal) constituting the main body of this thesis.

2. Estudio y modelación matemática del cambio metabólico de las bacterias responsables de la eliminación biológica de fósforo en el tratamiento de aguas residuales

Subjects
PAO, GAO, EBPR, SBR, Fósforo, Fosfatos, Polifosfatos, Glucógeno, PHA, VFA, Metabolismo, Modelo metabólico, Cambio metabólico, Recuperación de fósoro, PAO Tipo I, PAO Tipo II, Corto plazo, Largo plazo, Estequiometría, Cinética, Monod, and TECNOLOGIA DEL MEDIO AMBIENTE

3. Complementariedad de las inversiones a largo plazo y de capital de trabajo ante oportunidades de negocios y consideraciones de liquidez en países latinoamericanos [2015]

  • Valencia Herrera, Humberto
  • In Estudios Gerenciales October-December 2015 31(137):364-372

4. Desempenho de ações de empresas brasileiras após seu IPO: evidências de curto e de longo prazo [2015]

  • de Oliveira, Bruno Cals and Kayo, Eduardo Kazuo
  • In REGE - Revista de Gestão April-June 2015 22(2):173-186

5. Fuentes de financiamiento para el impulso del emprendimiento de los granjeros de Riohacha, Departamento de La Guajira, Colombia [2020]

  • Rodrigo Daniel Gámez Pitre, Elizabeth Palma Cardoso, and Iris Jiménez -Pitre
  • Revista de Micro e Pequenas Empresas e Empreendedorismo da Fatec-Osasco, Vol 6, Iss 2, Pp 289-311 (2020)
Subjects
granjas, corto plazo, largo prazo, producción, gerencia, Small and medium-sized businesses, artisans, handicrafts, trades, HD2340.8-2346.5, Business, and HF5001-6182
Abstract
Las empresas tratan de sobrevivir a los diversos cambios económicos de la actualidad que se están generando a nivel global en todas las áreas, por ello con el objetivo de analizar las fuentes de financiamiento para el impulso de emprendimiento de los granjeros de Riohacha, en el departamento de la Guajira, Colombia, se realizó una investigación descriptiva y no experimental por medio de encuestas a 86 sujetos, asociados a cinco granjas de Riohacha; el instrumento empleado fue un cuestionario con respuestas de escala tipo Lickert con valoraciones ponderadas. Por medio del cuestionario se pretendió dar respuesta a los financiamientos a corto plazo, largo plazo, y a los costos de producción como dimensiones de la variable Fuentes de Financiamiento. Los resultados indican que las dimensiones y la variable estudiada presentan un nivel moderado de aplicación en las granjas estudiadas. Se evidencio que la Fuentes de Financiamiento de los granjeros en el municipio Riohacha se implementa con moderada atención, por cuanto que dichas empresas buscan obtener el equilibrio entre las necesidades, crecimiento y recursos financieros, mediante la adquisición de inversión, financiamiento, administración y control de los recursos. En función de los resultados y conclusión se proponen lineamientos que potenciaron el emprendimiento en este sector económico del departamento de la Guajira en Colombia.

6. El plan de negocios y la rentabilidad [2020]

  • Juan Gaytán Cortés
  • Mercados y Negocios , Vol 1, Iss 42, Pp 143-156 (2020)
Subjects
plan de negocios, finanzas, corto plazo, Commerce, HF1-6182, Business, and HF5001-6182
Abstract
La información cuantitativa y cualitativa debe estar sustentada en propuestas estratégicas, del recurso humano, de operación, comerciales, económicas y financieras. Los objetivos que justifican la elaboración primero de la planeación estratégica y después del plan de negocios difieren según el ciclo de vida por el que cruza organización, los ciclos de la organización en general se dividen en: inicio, crecimiento, consolidación o declinación, a más del plan de negocios, también influye de forma significativa el sector en que se incorporará o la tipología de negocio en que se clasifique.

7. Revisión sistemática de literatura sobre modelos de pronósticos de consumo de energía eléctrica. [2020]

  • Mazzeo, Agustín, Sepúlveda-Cano, Lina, Villa, Luisa F., and Gallego-Burgos, Ricardo
  • Revista Ingenierías Universidad de Medellin. Ene-Jun2020, Vol. 19 Issue 36, p107-142. 36p.
Subjects
ENERGY consumption, ELECTRICAL energy, SUSTAINABLE development, ARTIFICIAL neural networks, and SCIENCE databases
Abstract
The growing consumption of electrical energy, climate change and the development of new technologies demand improvements for efficient energy management. An adequate forecast of the energy consumption is relevant for the sustainable development of any country. This article proposes a systematic review of selected literature based on search chains formed by the terms forecasting, energy and consumption applied to the scientific databases. In the article are compared mostly the models/techniques used, the considered variables and the error metrics used for obtaining knowledge on each one of the proposals, relieve its features and thus highlight the void in the literature that might be determinant for new research work. As conclusions are made evident the continuous use of neural networks for forecasting the energy consumption, the importance of determining the input variables and the error measuring for evaluating the precision of the models. Finally, the development of a model for the CEE short term forecast of a Latin-American developing country based on the comparison and evaluation of different techniques/models, variables and already existing tools is proposed as a new line of research. [ABSTRACT FROM AUTHOR]

8. Revisión sistemática de literatura sobre modelos de pronósticos de consumo de energía eléctrica [2020]

  • Agustín José Mazzeo, Lina María Sepúlveda Cano, Luisa Fernanda Villa Montoya, and Ricardo Alonso Gallego Burgos
  • Revista Ingenierías Universidad de Medellín, Vol 19, Iss 36, Pp 107-142 (2020)
Subjects
previsión, consumo de energía, corto plazo, largo plazo, redes neuronales, Technology, Engineering (General). Civil engineering (General), and TA1-2040
Abstract
El creciente consumo de energía eléctrica, los cambios climáticos y el desarrollo de nuevas tecnologías exigen mejoras para la gestión eficiente de la energía. El adecuado pronóstico del consumo de energía es relevante para el desarrollo sostenible de cualquier país. En este artículo se propone una revisión sistemática de literatura seleccionada a partir de cadenas de búsqueda formada por las palabras forecasting, energy y consumption aplicadas en las bases de datos científicas. Se comparan principalmente los modelos/técnicas utilizadas, las variables consideradas y las métricas de error usadas con el fin de obtener conocimiento de cada una de las propuestas, relevar sus características y así poder evidenciar el vacío en la literatura que podría determinar la semilla para un nuevo trabajo de investigación. Como conclusiones se observan el uso continuo de redes neuronales artificiales para el pronóstico de consumo, la importancia de determinar las variables de entrada y la medición del error para evaluar la precisión de los modelos. Finalmente, como nueva línea de investigación se propone desarrollar un modelo para el pronóstico de corto plazo de CEE para un país latinoamericano en vías de desarrollo, a partir de la comparación y evaluación de diferentes técnicas/modelos, variables y herramientas ya existentes

9. Evaluación de la hipótesis de Kuznets para Colombia 1977-2005 / Evaluation of the Kuznets Hypothesis for Colombia 1977-2005 / Avaliação da Hipótese de Kuznets para Colômbia 1977-2005 [2017]

  • Alonso Cifuentes, Julio César and González Terán, Ángela María
  • Apuntes del Cenes. June 2017 36(63):43-61
Subjects
SOCIAL SCIENCES, INTERDISCIPLINARY, desigualdad de ingresos, crecimiento económico, tasa de cambio, largo plazo, corto plazo, income inequality, economic growth, exchange rate, long run, short run, desigualdade de renda, o crescimento económico, taxas de câmbio, de longo prazo, and curto prazo
Abstract
Resumen La desigualdad en un país puede tener graves consecuencias en el desarrollo económico, por eso es importante el estudio de las causas de sus variaciones. Este documento pretende explicar cómo se ve afectada la desigualdad ante cambios en el crecimiento económico, la población y la tasa de cambio nominal. Siguiendo la hipótesis de la curva de Kuznets (1955), una desmejora del indicador de inequidad a corto plazo logra mayor igualdad a largo plazo, como efecto del crecimiento económico. El estudio se hace para Colombia, entre 1977 y 2005, con datos trimestrales. Nuestros resultados sugieren que la hipótesis de Kuznets puede explicar la relación entre crecimiento económico y distribución del ingreso en este país.
Inequality in a country can have serious consequences in the economic development and that is why it is important the study of the causes of its variations. Therefore, this document aims to explain how is affected the income inequality by changes in economic growth, population and nominal exchange rate. Following the Kuznets curve hypothesis (1955), a bad indicator of inequality in the short term is necessary to achieve better equality in the long term as an effect of the economic growth. The study is done for Colombia, between 1977 and 2005, with quarterly data. Our results show that the relation between economic growth and income distribution can be explained by the Kuznets hypothesis.
Resumo A desigualdade de renda pode ter consequências prejudiciais para o desenvolvimento de um país, mas especialmente na sua política social. Portanto, este documento tenta explicar como a desigualdade de renda está sendo afetado pelo crescimento econômico, população e a taxa nominal de câmbio. Após a Kuznets (1955) hipótese de um mau indicador da desigualdade no curto prazo é necessário para alcançar uma maior igualdade, a longo prazo como um efeito do crescimento económico. O papel é feito para a série trimestral da Colômbia de 1977 a 2005. Os resultados mostram que a relação entre desigualdade de renda e o crescimento económico pode ser explicada pela hipótese de Kuznets ".

10. Evaluación de la Hipótesis de Kuznets para Colombia con una aproximación de series de tiempo de corto y largo plazo: 1977-2005 [2017]

  • Julio César Alonso Cifuentes and Ángela María González Terán
  • Apuntes del CENES, Vol 36, Iss 63, Pp 43-62 (2017)
Subjects
Desigualdad de ingresos, crecimiento económico, tasa de cambio, largo plazo, corto plazo, Economics as a science, and HB71-74
Abstract
La desigualdad en un país puede tener graves consecuencias en el desarrollo económico, especialmente en lo que respecta a la política social, siendo de alta relevancia el estudio de las causas de sus variaciones. En ese sentido, este documento pretende explicar cómo se ve afectada la desigualdad ante cambios en el crecimiento económico, la población y la tasa de cambio nominal. Siguiendo la hipótesis de la curva de Kuznets (1955) una desmejora del indicador de inequidad en el corto plazo logra mayor igualdad en el largo plazo como efecto del crecimiento económico. El estudio se hace para Colombia con datos trimestrales, para el período entre 1977 y 2005. Nuestros resultados sugieren que la hipótesis de Kuznets puede explicar la relación entre crecimiento económico y distribución del ingreso en Colombia. Por otro lado, no se encuentra efecto de corto plazo sobre la distribución del ingreso con respecto al crecimiento poblacional, ni a la tasa de cambio. En el largo plazo, se encuentra que el aumento en la población empeora la desigualdad y que la depreciación del peso incrementa la desigualdad.

11. Short and long-term energy intake patterns and their implications for human body weight regulation [2014]

  • CHOW, Carson C, HALL, Kevin D, MATTES, Richard D, IBRC Symposium “Eating Patterns, Diet Quality and Energy Balance”(Purdue, IN, ; 2013-09-24), and Purdue University
  • IBRC SYMPOSIUM EATING PATTERNS, DIET QUALITY AND ENERGY BALANCE, Purdue University, September 24-26, 2013Physiology & behavior. 134:60-65
Subjects
Alimentation, Feeding, Alimentación, Bilan énergétique, Energy balance, Balance energético, Consommation alimentaire, Food intake, Consumo alimenticio, Court terme, Short term, Corto plazo, Homme, Human, Hombre, Long terme, Long term, Largo plazo, Modèle mathématique, Mathematical model, Modelo matemático, Poids corporel, Body weight, Peso corporal, Rétroaction, Feedback regulation, Retroacción, Body weight regulation, Energy intake, Feedback control, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Psychologie. Psychophysiologie, Psychology. Psychophysiology, Psychophysiologie du comportement, Behavioral psychophysiology, Psychologie. Psychanalyse. Psychiatrie, Psychology. Psychoanalysis. Psychiatry, Cognition, Physiology, morphology, Physiologie, morphologie, Psychophysiology, and Psychophysiologie
Abstract
Adults consume millions of kilocalories over the course of a few years, but the typical weight gain amounts to only a few thousand kilocalories of stored energy. Furthermore, food intake is highly variable from day to day and yet body weight is remarkably stable. These facts have been used as evidence to support the hypothesis that human body weight is regulated by active control of food intake operating on both short and long time scales. Here, we demonstrate that active control of human food intake on short time scales is not required for body weight stability and that the current evidence for long term control of food intake is equivocal. To provide more data on this issue, we emphasize the urgent need for developing new methods for accurately measuring energy intake changes over long time scales. We propose that repeated body weight measurements can be used along with mathematical modeling to calculate long-term changes in energy intake and thereby quantify adherence to a diet intervention and provide dynamic feedback to individuals that seek to control their body weight.

12. Probabilistic speech feature extraction with context-sensitive Bottleneck neural networks [2014]

  • WÖLLMER, Martin, SCHULLER, Björn, and ISCA Tutorial and Research Workshop on Non-Linear Speech Processing (NOLISP'11)(Las Palmas de Gran Canaria, ; 2011-11-07)
  • Neurocomputing (Amsterdam). 132:113-120
Subjects
Approche probabiliste, Probabilistic approach, Enfoque probabilista, Congestion trafic, Traffic congestion, Congestión tráfico, Contexte, Context, Contexto, Conversation, Conversación, Court terme, Short term, Corto plazo, Critère sélection, Selection criterion, Criterio selección, Décodage, Decoding, Desciframiento, Effet mémoire, Memory effect, Efecto memoria, Extraction forme, Pattern extraction, Extracción forma, Interface utilisateur, User interface, Interfase usuario, Langage naturel, Natural language, Lenguaje natural, Long terme, Long term, Largo plazo, Modélisation, Modeling, Modelización, Perception verbale, Verbal perception, Percepción verbal, Phonème, Phoneme, Fonema, Phonétique, Phonetics, Fonética, Production verbale, Verbal production, Producción verbal, Propagation longue distance, Long distance propagation, Propagación larga distancia, Reconnaissance forme, Pattern recognition, Reconocimiento patrón, Reconnaissance parole, Speech recognition, Reconocimiento voz, Réseau neuronal, Neural network, Red neuronal, Sensibilité contexte, Context aware, Sensibilidad contexto, Spontané, Spontaneous, Espontáneo, Traitement parole, Speech processing, Tratamiento palabra, Extraction caractéristique, Feature extraction, Extracción de características, Réseau neuronal récurrent, Recurrent neural nets, Red neuronal recurrente, Bidirectional speech processing, Bottleneck networks, Long Short-Term Memory, Probabilistic feature extraction, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines classiques de la physique (y compris les applications), Fundamental areas of phenomenology (including applications), Acoustique, Acoustics, Traitement des signaux acoustiques, Acoustic signal processing, Sciences appliquees, Applied sciences, Informatique, automatique theorique, systemes, Computer science, control theory, systems, Logiciel, Software, Organisation des mémoires. Traitement des données, Memory organisation. Data processing, Traitement des données. Listes et chaînes de caractères, Data processing. List processing. Character string processing, Intelligence artificielle, Artificial intelligence, Reconnaissance et synthèse de la parole et du son. Linguistique, Speech and sound recognition and synthesis. Linguistics, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Psychologie. Psychophysiologie, Psychology. Psychophysiology, Langage, Language, Production et perception du langage parlé, Production and perception of spoken language, Psychologie. Psychanalyse. Psychiatrie, Psychology. Psychoanalysis. Psychiatry, and Cognition
Abstract
We introduce a novel context-sensitive feature extraction approach for spontaneous speech recognition. As bidirectional Long Short-Term Memory (BLSTM) networks are known to enable improved phoneme recognition accuracies by incorporating long-range contextual information into speech decoding, we integrate the BLSTM principle into a Tandem front-end for probabilistic feature extraction. Unlike the previously proposed approaches which exploit BLSTM modeling by generating a discrete phoneme prediction feature, our feature extractor merges continuous high-level probabilistic BLSTM features with low-level features. By combining BLSTM modeling and Bottleneck (BN) feature generation, we propose a novel front-end that allows us to produce context-sensitive probabilistic feature vectors of arbitrary size, independent of the network training targets. Evaluations on challenging spontaneous, conversational speech recognition tasks show that this concept prevails over recently published architectures for feature-level context modeling.

13. Complementariedad de las inversiones a largo plazo y de capital de trabajo ante oportunidades de negocios y consideraciones de liquidez en países latinoamericanos. [2015]

  • Herrera, Humberto Valencia
  • Estudios Gerenciales. Oct-Dec2015, Vol. 31 Issue 137, p364-372. 9p.
Abstract
The objective of the study is the analysis of the relation between long term investment and investment in working capital, using the generalized least squares method for panel data with error correction for heteroscedasticity, and panel specific autocorrelation. From the above, it is found that investment in long-term assets in publicly traded companies from 7 major Latin American countries is preceded by increases in working capital, which strengthens the hypothesis that this occurs in response to improved business opportunities. This relationship is statistically significant in general and in companies that have high or medium, but not low leverage. [ABSTRACT FROM AUTHOR]

14. Cuellos de botella y recursos restringidos por la capacidad en las instituciones del sector privado [2018]

  • Sally Reasco Gavilanes, Martha Guadalupe Acosta Roby, July Yojana Gaibor Gaibor, and Georgina Encalada Tenorio
  • Revista Caribeña de Ciencias Sociales, 2018, 2018-05.
Subjects
Marketing, Manufactura, Sistema, Meta, Restricciones, Líneas de comunicación, Extrovertida, Ralentizar, Corto plazo, Largo plazo, and Planta fabril.
Abstract
Según (Pérez, 2017) “La teoría de las restricciones o de cuellos de botella fue descrita por primera vez por Eliyahu Goldratt, un doctor en Física israelí, en los años 80’s, y está basada en el fenómeno de que los procesos de cualquier ámbito solo progresan a la velocidad del paso más lento. La manera de balancear el proceso es lograr acelerar ese paso, tratando de que trabaje hasta el límite de su capacidad, para acelerar así el proceso completo. Los factores limitantes, esos pasos lentos, se denominan restricciones, embudos o cuellos de botella†. Esta teoría es usada frecuentemente en la industria. Decimos que en nuestra cadena de producción tenemos un cuello de botella cuando una fase de nuestro proceso productivo es más lenta que las demás y la producción total se ve limitada a causa de ella. En este ámbito, además, los dividen en dos: a corto y largo plazo. Los a corto plazo son temporales y no suelen ser un problema —un ejemplo de uno sería un trabajador tomando unos días de descanso que provoca un embudo en los pedidos—. Los a largo plazo ocurren todo el tiempo y de forma acumulativa y sí pueden ralentizar considerablemente la producción.

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16. Stock trading rule discovery with an evolutionary trend following model [2015]

  • YONG HU, BIN FENG, XIANGZHOU ZHANG, NGAI, E. W. T, and MEI LIU
  • Expert systems with applications. 42(1):212-222
Subjects
Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Recherche operationnelle. Gestion, Operational research. Management science, Recherche opérationnelle et modèles formalisés de gestion, Operational research and scientific management, Sélection et gestion de portefeuilles, Portfolio theory, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Informatique théorique, Theoretical computing, Algorithmique. Calculabilité. Arithmétique ordinateur, Algorithmics. Computability. Computer arithmetics, Logiciel, Software, Systèmes informatiques et systèmes répartis. Interface utilisateur, Computer systems and distributed systems. User interface, Intelligence artificielle, Artificial intelligence, Apprentissage et systèmes adaptatifs, Learning and adaptive systems, Algorithme apprentissage, Learning algorithm, Algoritmo aprendizaje, Algorithme évolutionniste, Evolutionary algorithm, Algoritmo evoluciónista, Analyse conceptuelle, Conceptual analysis, Análisis conceptual, Analyse tendance, Trend analysis, Análisis tendencia, Apprentissage renforcé, Reinforcement learning, Aprendizaje reforzado, Arbre décision, Decision tree, Arbol decisión, Bourse valeurs, Stock exchange, Bolsa valores, Court terme, Short term, Corto plazo, Coût transaction, Transaction cost, Coste transacción, Découverte connaissance, Knowledge discovery, Descubrimiento conocimiento, Dérive génétique, Genetic drift, Deriva genética, Economie, Economy, Economía, Efficacité, Efficiency, Eficacia, Fouille donnée, Data mining, Busca dato, Indice économique, Economic index, Indice económico, Intelligence artificielle, Artificial intelligence, Inteligencia artificial, Investissement, Investment, Inversión, Long terme, Long term, Largo plazo, Marché financier, Financial market, Mercado financiero, Marché à la baisse, Bear market, Mercado bajista, Marché à la hausse, Bull market, Mercado alcista, Modèle hybride, Hybrid model, Modelo híbrido, Modélisation, Modeling, Modelización, Poursuite modèle, Model following, Seguimiento modelo, Recherche et développement, Research and development, Investigación desarrollo, Réseau neuronal, Neural network, Red neuronal, Résultat expérimental, Experimental result, Resultado experimental, Transmission en continu, Streaming, Transmisión fluyente, Algorithme sans mémoire, Oblivious algorithm, Algoritmo sin Memória, Concept drift, Evolutionary trend following algorithm (eTrend), Trading rule discovery, and eXtended Classifier System (XCS)
Abstract
Evolutionary learning is one of the most popular techniques for designing quantitative investment (QI) products. Trend following (TF) strategies, owing to their briefness and efficiency, are widely accepted by investors. Surprisingly, to the best of our knowledge, no related research has investigated TF investment strategies within an evolutionary learning model. This paper proposes a hybrid long-term and short-term evolutionary trend following algorithm (eTrend) that combines TF investment strategies with the extended Classifier Systems (XCS). The proposed eTrend algorithm has two advantages: (1) the combination of stock investment strategies (i.e., TF) and evolutionary learning (i.e., XCS) can significantly improve computation effectiveness and model practicability, and (2) XCS can automatically adapt to market directions and uncover reasonable and understandable trading rules for further analysis, which can help avoid the irrational trading behaviors of common investors. To evaluate eTrend, experiments are carried out using the daily trading data stream of three famous indexes in the Shanghai Stock Exchange. Experimental results indicate that eTrend outperforms the buy-and-hold strategy with high Sortino ratio after the transaction cost. Its performance is also superior to the decision tree and artificial neural network trading models. Furthermore, as the concept drift phenomenon is common in the stock market, an exploratory concept drift analysis is conducted on the trading rules discovered in bear and bull market phases. The analysis revealed interesting and rational results. In conclusion, this paper presents convincing evidence that the proposed hybrid trend following model can indeed generate effective trading guidance for investors.

17. SPC forecasting system to mitigate the bullwhip effect and inventory variance in supply chains [2015]

  • COSTANTINO, Francesco, DI GRAVIO, Giulio, SHABAN, Ahmed, and TRONCI, Massimo
  • Expert systems with applications. 42(3):1773-1787
Subjects
Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Recherche operationnelle. Gestion, Operational research. Management science, Recherche opérationnelle et modèles formalisés de gestion, Operational research and scientific management, Théorie de la décision. Théorie de l'utilité, Decision theory. Utility theory, Gestion des stocks, gestion de la production. Distribution, Inventory control, production control. Distribution, Logistique, Logistics, Carte contrôle, Control chart, Carta control, Commande prédictive, Predictive control, Control predictiva, Court terme, Short term, Corto plazo, Demande marché, Demand(contract), Demanda mercado, Effet coup fouet, Bullwhip effect, Efecto latigazo, Gestion stock, Inventory control, Administración depósito, Lissage exponentiel, Exponential smoothing, Alisado exponencial, Logistique, Logistics, Logística, Maîtrise statistique processus, Statistical process control, Control estadístico proceso, Moyenne mobile, Moving average, Promedio móvil, Politique optimale, Optimal policy, Política óptima, Prévision, Forecasting, Previsión, Règle décision, Decision rule, Regla decisión, Réapprovisionnement, Replenishment, Nuevo abastecimiento, Traitement signal, Signal processing, Procesamiento señal, Variance, Variancia, Inventory variance, Order-up-to, SPC, Simulation, and Supply chain
Abstract
Demand signal processing contributes significantly to the bullwhip effect and inventory instability in supply chains. Most previous studies have been attempting to evaluate the impact of available traditional forecasting methods on the bullwhip effect. Recently, some researchers have employed SPC control charts for developing forecasting and inventory control systems that can regulate the reaction to short-run fluctuations in demand. This paper evaluates a SPC forecasting system denoted as SPC-FS that utilizes a control chart approach integrated with a set of simple decision rules to counteract the bullwhip effect whilst keeping a competitive inventory performance. The performance of SPC-FS is evaluated and compared with moving average and exponential smoothing in a four-echelon supply chain employs the order-up-to (OUT) inventory policy, through a simulation study. The results show that SPC-FS is superior to the other traditional forecasting methods in terms of bullwhip effect and inventory variance under different operational settings. The results confirm the previous researches that the moving average achieves a lower bullwhip effect than the exponential smoothing, and we further extend this conclusion to the inventory variance.

18. Intersection traffic flow forecasting based on v-GSVR with a new hybrid evolutionary algorithm [2015]

  • HUANG, Min-Liang
  • Neurocomputing (Amsterdam). 147:343-349
Subjects
Cognition, Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Informatique théorique, Theoretical computing, Algorithmique. Calculabilité. Arithmétique ordinateur, Algorithmics. Computability. Computer arithmetics, Logiciel, Software, Organisation des mémoires. Traitement des données, Memory organisation. Data processing, Traitement des données. Listes et chaînes de caractères, Data processing. List processing. Character string processing, Transports terrestres, transports aeriens, transports maritimes, constructions navales, Ground, air and sea transportation, marine construction, Transports et trafic routiers, Road transportation and traffic, Algorithme génétique, Genetic algorithm, Algoritmo genético, Algorithme évolutionniste, Evolutionary algorithm, Algoritmo evoluciónista, Analyse conceptuelle, Conceptual analysis, Análisis conceptual, Analyse régression, Regression analysis, Análisis regresión, Carrefour routier, Road junction, Cruce carretera, Chaos, Caos, Chaussée, Pavement, Calzada, Classification à vaste marge, Vector support machine, Máquina ejemplo soporte, Condition météorologique, Atmospheric condition, Condición meteorológica, Corps fonction, Function field, Campo función, Court terme, Short term, Corto plazo, Croisement routier, Cross roads, Intersección carretera, Culture, Cultivo, Ecoulement trafic, Traffic flow, Flujo tráfico, Erreur aléatoire, Random error, Error aleatorio, Etude expérimentale, Experimental study, Estudio experimental, Fonction perte, Loss function, Función pérdida, Gestion trafic, Traffic management, Gestión tráfico, Intersection, Intersección, Intervalle temps, Time interval, Intervalo tiempo, Modélisation, Modeling, Modelización, Processus Gauss, Gaussian process, Proceso Gauss, Prévision, Forecasting, Previsión, Route, Highway, Carretera, Système chaotique, Chaotic systems, Temps séjour, Residence time, Tiempo estancia, Chaos map, Cloud model, Gaussian loss function, Short-term traffic flow forecasting, and Support vector machine
Abstract
To deal well with the normally distributed random error existed in the traffic flow series, this paper introduces the v-Support Vector Regression (v-GSVR) model with the Gaussian loss function to the prediction field of short-term traffic flow. A new hybrid evolutionary algorithm (namely CCGA) is established to search the appropriate parameters of the v-GSVR, coupling the Chaos map, Cloud model and genetic algorithm. Consequently, a new forecasting approach for short-term traffic flow, combining v-GSVR model and CCGA algorithm, is proposed. The forecasting process considers the traffic flow for the road during the first few time intervals, the traffic flow for the upstream road section and weather conditions. A numerical example from the intersection between Culture Road and Shi-Full Road in Banqiao is used to verify the forecasting performance of the proposed model. The experiment indicates that the model yield more accurate results than the compared models in forecasting the short-term traffic flow at the intersection.

19. Short-term antidepressant treatment of bipolar depression: Are ISBD recommendations useful in clinical practice? [2015]

  • TUNDO, Antonio, CALABRESE, Joseph R, PROIETTI, Luca, and DE FILIPPIS, Rocco
  • Journal of affective disorders. 171:155-160
Subjects
Trouble de l'humeur, Mood disorder, Trastorno humor, Antidépresseur, Antidepressant agent, Antidepresor, Court terme, Short term, Corto plazo, Psychotrope, Psychotropic, Psicotropo, Recommandation, Recommendation, Recomendación, Traitement, Treatment, Tratamiento, Trouble bipolaire, Bipolar disorder, Trastorno bipolar, Pratique clinique, Antidepressants, Bipolar depression, Short-term treatment, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Pharmacologie. Traitements medicamenteux, Pharmacology. Drug treatments, Neuropharmacologie, Neuropharmacology, Psychoanaleptiques: stimulant snc, antidépresseur, nootrope, normothymique..., (maladie d'alzheimer), Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease), Psychopathologie. Psychiatrie, Psychopathology. Psychiatry, Etude clinique de l'adulte et de l'adolescent, Adult and adolescent clinical studies, Troubles de l'humeur, Mood disorders, Troubles bipolaires, Bipolar disorders, Divers, Miscellaneous, Psychologie. Psychanalyse. Psychiatrie, Psychology. Psychoanalysis. Psychiatry, PSYCHOPATHOLOGIE. PSYCHIATRIE, Psychopharmacologie, Psychopharmacology, Psychoanaleptiques: stimulant SNC antidépresseur, nootrope, normothymique…, Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer…, Cognition, Psychology, psychopathology, psychiatry, and Psychologie, psychopathologie, psychiatrie
Abstract
Objectives: The study aimed to test the effectiveness of the ISBD Guidelines for short-term AD treatment of BP depression. Methods: The study sample included 255 patients with mood disorders (154 UP, 49 BP-I, 52 BP-II). Response was defined as a HDRS21 total score < 7 at 12 weeks of treatment and remission as a > 50% reduction of baseline HDRS21 total score sustained for 8 weeks. Results: Response was achieved by 64.9% of patients with UP disorder, 75.5% of patients with BP-I disorder and 75.0% with BP-II disorder without significant differences (χ2=3.0, p=0.219). The remission rate did not differ significantly among groups (χ2=3.8, p=0.151). The dropout rate was significantly higher for patients with UP (18.2%) than for patients with BP-I (2%) and BP-II (7.7%) disorder (χ2=10.1, p=0.006). Concerning AD safety, one patient with BP-I depression committed a suicide attempt and AD-emerging switch was observed in 2.9% of patients, 2 with BP-I and 1 with BP-II disorder. Limitations: The observational nature of the study and unblinded outcomes assessment. Conclusions: Our findings confirm the usefulness of ISBD Guidelines for short-term AD treatment of BP depression. These patients appear to have similar response and remission rate to those observed in UP depression and do not exhibit significant switch rates or risk of suicide. Our results are limited to patients with pure bipolar depression (excluding those with broadly defined mixed states), treated with ADs-mood stabilizers combination. We suggest to partially modify ISBD Recommendations 1 and 4, to include potential responders and to improve safety.

20. Complementariedad de las inversiones a largo plazo y de capital de trabajo ante oportunidades de negocios y consideraciones de liquidez en países latinoamericanos [2015]

  • Humberto Valencia Herrera
  • Estudios Gerenciales, Vol 31, Iss 137, Pp 364-372 (2015)
Subjects
Administración financiera, Corto plazo, Inversión, Latinoamérica, Business, and HF5001-6182
Abstract
El objetivo del estudio es analizar la relación entre la inversión a largo plazo y la inversión de capital de trabajo, para lo cual se utiliza el método de mínimos cuadrados generalizados para paneles con corrección de errores por hetercedasticidad y autocorrelación específica por panel. A partir de lo anterior se encuentra que la inversión en activos a largo plazo en las empresas que cotizan en la bolsa de 7 de los principales países latinoamericanos está precedida por aumentos en el capital de trabajo, lo que fortalece la hipótesis de que se da en respuesta a mejoras en las oportunidades de negocios. Esta relación es estadísticamente significativa en lo general y en empresas que tienen alto o mediano apalancamiento, más no en las de bajo.

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