in this article, multiple-product pvrp with pickup and delivery that is used widely in goods distribution or other service companies, especially by railways, was introduced. a mathematical formulation was provided for this problem. each product had a set of vehicles which could carry the product and pickup and delivery could simultaneously occur. to solve the problem, two meta-heuristic methods...

This paper describes a railway system simulation to be used by train railway system operators. We have developed a learning tool for education, but, besides, different railway system models can be analyzed. Wedonot need to build the physical railway model, but may experiment with the planned system on the computer. The modeled system can be built easily and effectively and its behaviour may be ...

We analyse the role of new weak and strong commensurability conditions on efficiency measures especially productivity measurement. If fails, then a index (indicator) may exhibit homogeneity bias yielding inconsistent contradictory results. In particular, we show that Luenberger indicator is sensitive to proportional changes in input-output quantities, while Malmquist not affected by such change...

Based on the panel data of 284 prefecture-level cities in China from 2005 to 2019, this paper adopts a time-varying difference-in-differences model as quasi-natural experiment empirically test impact and mechanism operation China–Europe Railway Express green total factor productivity. The empirical results show that can significantly improve urban In addition, heterogeneity manifests promotion ...

Agricultural intensification is placing tremendous pressure on the soil's capacity to maintain its functions leading to large-scale ecosystem degradation and loss of productivity in the long term. Therefore, there is an urgent need to find early indicators of soil health degradation in response to agricultural management. In recent years, major advances in soil meta-genomic and spatial studies ...