According to EU legislation pigs must have access to rooting material, and the aim of the study was to quantify growing pigs’ preferences among six different rooting materials. The relative attractiveness of six rooting materials was assessed in an operant conditioning set-up using concurrent schedules of reinforcement. Twelve pigs were tested with all six combinations of the reference material...

in a structural time series regression model, binary variables have been used to quantify qualitative or categorical quantitative events such as politic and economic structural breaks, regions, age groups and etc. the use of the binary dummy variables is not reasonable because the effect of an event decreases (increases) gradually over time not at once. the simple and basic idea in this paper i...

the results of performance evaluation in the creation of employment during the recent years indicates that employment goals in the third development plan were not achieved while goals in the area of production and investment growth rates were fulfilled accordingly. the analysis of labor demand models in the third development plan is conducted in order to identify their weaknesses in predicting ...

today, companies need to make use of appropriate patterns such as supply chain management system to gain and preserve a position in competitive world-wide market. supply chain is a large scaled network consists of suppliers, manufacturers, warehouses, retailers and final customers which are in coordination with each other in order to transform products from raw materials into finished goods wit...

in this paper, a robust model presented is developed for hub covering flow problem in which hubs have capacity. this problem has two objective functions converting to a single-objective problem by using weighting method. firstly, the problem will be formulated in a certain case. then, by considering the demand as a non-random variable, it will be modeled by robust optimization. finally, by usin...