Including widespread geometry formats in semantic graphs using RDF literals

The exchange of building data involves both geometric and non-geometric data. A promising Linked Data approach is to embed data from existing geometry formats inside Resource Description Framework (RDF) literals. Based on a study of relevant specifications and related work, this toolset-independent approach was found suitable for the exchange of geometric construction data. To implement the approach in practice, the File Ontology for Geometry formats (FOG) and accompanying modelling method is developed. In a proof-of-concept web application that uses FOG, is demonstrated how geometry descriptions of different existing formats are automatically recognised and parsed

A dynamic day-ahead paratransit planning problem

Abstract We consider a dynamic planning problem for the transport of elderly and disabled people. The focus is on a decision to make one day ahead: which requests to serve with own vehicles, and which ones to assign to subcontractors, under uncertainty of late requests which are gradually revealed during the day of operation. We call this problem the Dynamic Day-ahead Paratransit Planning problem. The developed model is a nonstandard two-stage recourse model in which ideas from stochastic programming and online optimization are combined: in the first stage clustered requests are assigned to vehicles, and in the dynamic second-stage problem an event-driven approach is used to cluster the late requests once they are revealed and subsequently assign them to vehicles. A genetic algorithm is used to solve the model. Computational results are presented for randomly generated data sets. Furthermore, a comparison is made to a similar problem we studied earlier in which the simplifying but unrealistic assumption has been made that all late requests are revealed at the beginning of the day of operation.

Implementation of new regulatory rules in a multistage ALM model for Dutch pension funds

This paper discusses the implementation of new regulatory rules in a multistage recourse ALM model for Dutch pension funds. The new regulatory rules, which are called the ?Financieel Toetsingskader?, are effective as of January 2007 and have deep impact on the issues of valuation of liabilities, solvency, contribution rate, and indexation. Multistage recourse models have proved to be valuable for pension fund ALM. The ability to include the new regulatory rules would increase the practical value of these models.

Integrated chance constraints: reduced forms and an algorithm

We consider integrated chance constraints (ICC), which provide quantitative alternatives for traditional chance constraints.We derive explicit polyhedral descriptions for the convex feasible sets induced by ICCs, for the case that the underlying distribution is discrete. Based on these reduced forms, we propose an efficient algorithm for this problem class. The relation to conditional value-at-risk models and (simple) recourse models is discussed, leading to a special purpose algorithm for simple recourse models with discretely distributed technology matrix. For both algorithms, numerical results are presented.

Asset liability management modeling using multi-stage mixed-integer stochastic programming

A pension fund has to match the portfolio of long-term liabilities with the portfolio of assets. Key instruments in strategic Asset Liability Management (ALM) are the adjustments of the contribution rate of the sponsor and the reallocation of the investments in several asset classes at various points of time. We formulate a multistage mixed-integer stochastic program to model this ALM process. Special attention is paid to the use of binary variables.

ALM model for pension funds : numerical results for a prototype model

A multistage mixed-integer stochastic programming model is formulated for an Asset Liability Management problem for pension funds. Since these models are too difficult to solve for realistically sized problems, a heuristic is described. Numerical results for several instances of a prototype model are presented and discussed.

Optimizing electricity distribution using two-stage integer recourse models

We consider two planning problems faced by an electricity distributor. Electricity can be ob-tained both from power plants and small generators such as hospitals and greenhouses, whereas the future demand for electricity is uncertain. The price of electricity obtained from the power plants depends on quota that are to be determined in a yearly contract, whereas the (given) contracts with small generators contain various constraints on switching them on or off