A.T.M. Aerts

A flexible, agent-based ICT architecture for virtual enterprises

Virtual enterprises (VEs), in our view, are conglomerates of regular enterprises that collaborate on an ad hoc basis to carry out an inter-organisational business process. The virtual enterprise has a dynamic structure that depends on the particular process that needs to be carried out. Enterprises can join or leave the virtual enterprise at short notice, depending on the capacity and the opportunity. In recent papers, we studied the use of a mobile agent framework to support the co-ordination of the primary process in a virtual enterprise. We argued that the installation of standard software modules, called service bridges or docks, at the participant enterprises provides a suitable infrastructure for the use of mobile agents for this purpose.The deployment of mobile software agents using such modules has been studied in applications such as networked electronic trading and mediation of negotiations. The emphasis in these applications lies on demonstrating the potential of mobile agents for the support of complex decision problems. In this paper, we study the flexibility requirements an agile enterprise such as the VE imposes on its ICT support. We argue that a mobile agent-based ICT architecture will provide the required flexibility. We will discuss a number of change cases to illustrate flexibility. We examine the impact of these change cases on the requirements on the agent-agent and on the agent-system interaction.

A reliable mobile agents architecture

This paper describes the design of a novel mobile agent system that supports the flexible and reliable interaction of autonomous components in an object-oriented distributed system. It discusses the object-oriented design of the overall system together with a number of important components in terms of the most important design decisions. A detailed description of the reliability model is given in terms of the failure hypothesis and the related recovery protocols. Special emphasis is given to the generality and efficiency of the implementation and a number of preliminary experiences are described.

Mediating negotiations in a virtual enterprise via mobile agents

In this paper, we propose a systematisation of the monitoring and control aspects in a virtual enterprise (VE). As an instrument, we use the mobile agent paradigm, defining the concept of a mobile agent Web (MA-Web). One of the roles of the agents in this environment is to mediate negotiations between the parties of the VE. We make some assumptions about the new behaviour and code of conduct in the MA-Web, such as the willingness to share data and knowledge.

Narrow dibaryons of strangeness S = −1?

Abstract In a simple model consisting of wave function rearrangement followed by a final state interaction, we estimate the widths for the decay of S = −1 six-quark dibaryons into hyperon + nucleon (YN). For the lowest-lying dibaryons D s,t , in the bag model of quark cluster structure Q 4 ⊗ Q 2 ( 1 P 1 or 3 P 0, 1, 2 ), we predict very small widths ( Γ ≲ 10 MeV for m D ≲ 2.2 GeV).

QCD, bags, and hadron masses

Abstract Hadronic mass spectra are systematically fitted to a QCD and bag motivated expression in which the quark interaction matrix elements are allowed to assume best values. A statistically significant fit is found with B 1 4 ≈ 170 MeV. The inclusion of surface energy σ has been studied and we have found a second, equally significant fit with B 1 4 ≈ 210 MeV and σ ≈ 40 MeV/fm2. However, the corresponding hadrons are unacceptably small, i.e. R ≈ 0.5 fm. Selected strange multiquark states are recomputed and found to have generally a higher mass than currently believed.

On the design of a mobile agent Web for supporting virtual enterprises

In this paper we discuss the design of a mobile agent based infrastructure for monitoring and controlling activities in a Virtual Enterprise (VE). We define the concepts of the Virtual Enterprise and the Mobile Agent Web (MA-web).

THERMODYNAMICS OF BOSON-FERMION DUALITY IN CONFINED TWO-DIMENSIONAL MODELS

Abstract The partition functions of massless (QED) 2 and (QCD) 2 are calculated in a weak coupling limit defined by using a finite volume as infrared cut-off. A coherent state formalism is used to treat constraints from gauge invariance and show that the results are those expected from bosonization. We also present a simple derivation of the physical spectrum of (QED) 2 confined to a bag for any coupling.

Flexible Infrastructure for Virtual Enterprises

In recent papers we studied the use of a mobile agent framework to support the primary process in a Virtual Enterprise. We argued that the installation of standard software modules, called service bridges or docks, at the participant enterprises provides a suitable infrastructure for the use of mobile agents. The deployment of mobile software agents using such modules has been studied in applications such as networked electronic trading and mediation of negotiations. The emphasis in these applications lies on demonstrating the potential of mobile agents for the support of complex decision problems. As such they focus on the agent — agent interaction. In this paper we study the agent — system interaction. We will discuss a number of change cases and examine their impact on the requirements on the agent — agent and on the agent — system interaction arising from the need for flexibility.

Message Flow Control

High level communication by means of the exchange of messages between different organizations or organizational units is studied. The concepts of business transaction and business transaction protocol are discussed. Message exchanges are controlled by a message handler that enforces a transaction protocol. The design and implementation of a generic message handler is described. The design is independent of a specific application. It offers a flexible implementation of protocols: dedicated subprocesses handle each message type. Changes in a protocol can easily be accommodated by adapting the subprocesses. A prototype has been written in the executable specification language ExSpect. The protocols can be validated by simulating the message exchange for a number of cases. As an application of the prototype, a party in a logistic chain using EDI is described.

A database perspective on CMS detector data

Building a state of the art high energy physics detector like CMS (Compact Muon Solenoid) requires strict interoperability and coherency in the design and construction of all sub-systems comprising the detector. This issue is especially critical for the many database components that are planned for storage of the various categories of data related to the construction, operation, and maintenance of the detector like slow control data, conditions data, calibration data, and event meta data. The data structures needed to operate the detector as a whole need to be present in the database before the data is entered. Changing these structures for a database system that already contains a substantial amount of data is a very time and labour consuming exercise that needs to be avoided. Cases where the detector needs to be treated as a whole are detector operation (control, error tracking, conditions monitoring) and the interfacing of the reconstruction and simulation software. In this paper we propose to use the detector geometry as the structure connecting the various elements. The design and implementation of a relational database that captures the CMS detector geometry and the detector components is discussed. The detector geometry can serve as a core component in several other databases in order to make them interoperable. It also provides a common viewpoint between the physical detector and its image in the reconstruction software. Some of the necessary extensions to the detector description are discussed.