Mark Polman

Coordination in a supply chain for bulk chemicals

A chemical plant in the Netherlands uses large annual supplies of a bulk chemical. A number of suppliers deliver their parcels from overseas by short sea vessel to a transshipment point where they are stored using a tank farm. Transportation from the transshipment point to the plant takes place by barge. Coordination of the schedules of vessels and barge provides the opportunity for board to board loading. Board to board loading provides clear benefits for the plants operator, as it requires less handling and intermediate storage at the transshipment point. We demonstrate this by experiments conducted with a simulation model. The results are confirmed by analytical means.

A structured design technique for distributed programs

A non-formal motivation and description is given of ADL-d, a graphical design technique for parallel and distributed software. ADL-d allows a developer to construct an application in terms of communicating processes. The technique distinguishes itself from others by its rigid orthogonal approach to communication modeling, which is advantageous in many areas. Without being committed to one particular design method, ADL-d as a technique can be used from the early phases of application design through phases that concentrate on algorithmic design, and final implementation on some target platform. The authors discuss and motivate all ADL-d components, including recently incorporated features such as support for connection-oriented communication, and support for modeling dynamically changing communication structures.

Complexity Dimensions and Learnability

In a discussion of the Vapnik Chervonenkis (VC) dimension ([7]), which is closely related to the learnability of concept classes in Valiants PAC-model ([6]), we will give an algorithm to compute it. Furthermore, we will take Natarajans equivalent dimension for well-ordered classes into a more general scheme, by showing that these well-ordered classes happen to satisfy some general condition, which makes it possible to construct for a class a number of equivalent dimensions. We will give this condition, as well as a relatively efficient algorithm for the calculation of one such dimension for well-ordered classes.

Formalizing a design technique for distributed programs

ADL-d is a graphical design technique for parallel and distributed software, in which communication modeling plays a central part. Recently the authors have used formal methods to define ADL-ds semantics. The original objective was to provide well-defined guidelines for future implementations of ADL-ds communication constructs, but, as it turned out, significant feedback resulted to the notation itself. They give an outline of the ADL-d notation and its intuitive semantics. They also introduce the formal semantics, and discuss what impact this formalization has had on the original notation.

Design Level Support for Parallel and Distributed Applications

The growing interest in using a cluster of workstations as the target platform for high-performance applications, has again emphasized the need for support tools in application design, which is the subject of this paper. Here, we use as a discussion vehicle a graphical technique, ADL-D, that allows a developer to construct an application in terms of communicating processes. The technique distinguishes itself by its use of highly orthogonal concepts, and the support for automated code generation. Developers are encouraged to concentrate on designing components in isolation, making the complex design space more manageable than would otherwise be the case. Adl-d can be used from the early stages of application design through phases concerning algorithmic design, and final implementation on some target platform.