Dinámica no lineal del mercado del café en Colombia

Abstract

El presente artículo tiene como objetivo modelar las variables de oferta, demanda y stock del mercado del café verde colombiano comercializado como commodity. A partir de estas variables se formula un modelo de sistemas dinámicos usando ecuaciones diferenciales ordinarias, las cuales permiten observar el comportamiento del mercado de este producto. El análisis realizado tiene en cuenta algunos parámetros, como las tasas de exportación e importación, estimados a partir de datos históricos sobre el mercado del café reportados por las entidades oficiales. En el documento se muestra la formulación del modelo, seguido por el cálculo de los puntos de equilibrio y su estabilidad. Por último, se presenta la simulación de las variables de estado.

Environmental Impacts Assessment in Suspension PVC Production Process Using Computer-Aided Process Engineering

“…The results of Cases 3 and 4 show that energy consumption has significant effects on the PEI generation of the process due to the emission of gaseous substances with high environmental impacts. Environmental assessments in the literature are conducted for other polymer processes, such as the polypropylene (PP) process studied by Jimenez-Varon [31] and the polyethylene (PE) process analyzed by Velasquez-Barrios [32]. The global impact indicators such as output PEI per ton of product and per day can be used to compare each production process.…”

“…Environmental assessments in the literature are conducted for other polymer processes, such as the polypropylene (PP) process studied by Jimenez-Varon [31] and the polyethylene (PE) process analyzed by Velasquez-Barrios [32]. The global impact indicators such as output PEI per ton of product and per day can be used to compare each production process.…”

Chemical and Process Inherent Safety Analysis of Large-Scale Suspension Poly(Vinyl Chloride) Production

“…In terms of operating conditions, the process exhibits a good score thanks to its moderate to low operating conditions (temperature and pressure) at 250 • C and 13.5 bar, while the acetone production process has a higher temperature of 507 • C and the benzene production process has a pressure of 25 bar [38]. Meanwhile, the ethylene production process involves temperatures close to 300 • C and pressures of 2000 bar [39]. The Safety Structure Index of the PVC suspension process was determined as mostly unsafe, but this could be an overestimation since Carvalho et al estimated the I ST,max for the VCM production process as neutral [38]; at the same time, Lozano assigned a score of 0 to the acetone, butyl acetate and cumene production processes, arguing that all processes are proven technologies-however, accident reports point out that there is at least a source of concern regarding how the VCM is handled throughout some process units, but the risk is lower in certain parts of the process due to the removal of the VCM, such as the drying section.…”

“…In terms of operating conditions, the process exhibits a good score thanks to its moderate to low operating conditions (temperature and pressure) at 250 °C and 13.5 bar, while the acetone production process has a higher temperature of 507 °C and the benzene production process has a pressure of 25 bar [38]. Meanwhile, the ethylene production process involves temperatures close to 300 °C and pressures of 2000 bar [39]. The Safety Structure Index of the PVC suspension process was determined as mostly unsafe, but this could be For the PVC suspension process, the risks from the chemical side cannot be removed, only contained, while the safety process indexes are more approachable in terms of elimination.…”