W.H.A. Schilders

Models for integrated components coupled with their EM environment

Purpose – The main aim of this study is the modelling of the interaction of on‐chip components with their electromagnetic environment.Design/methodology/approach – The integrated circuit is decomposed in passive and active components interconnected by means of terminals and connectors which represent intentional and parasitic couplings of a capacitive and inductive nature. Reduced order models are extracted independently for each component.Findings – The paper shows that one of the main theoretical problems encountered in the modelling of RF components is the difficulty to define a unique terminal voltage, independent of the integration path (this independence being a condition to allow the connection of the component in an electric circuit, where the voltage does not depend of the path shape). The concept of an electromagnetic circuit element that allows the interconnection between IC models is proposed as a solution for this drawback. The system is described either with EM field models, or by electric/m...

INDEX-AWARE MODEL ORDER REDUCTION FOR LINEAR INDEX-2 DAES WITH CONSTANT COEFFICIENTS ∗

A model order reduction method for index-2 differential-algebraic equations (DAEs) is introduced, which is based on the intrinsic differential equations and on the remaining algebraic constraints. This extends the method introduced in a previous paper for index-1 DAEs. This procedure is implemented numerically and the results show numerical evidence of its robustness over the traditional methods.

European success stories in industrial mathematics

Foreword.- Preface.- Introduction.- Health Biology.- Energy & Environment.- Finance & Modelling.- Automotive Industry & Manufacturing.- Aerospace & Electronics.- Services, Transport & Logistics.- Annex. Summary Report of the E.S.F. Forward Look.

Delphi4LED — from measurements to standardized multi-domain compact models of LED: A new European R&D project for predictive and efficient multi-domain modeling and simulation of LEDs at all integration levels along the SSL supply chain

There are a few bottlenecks hampering efficient design of products on different integration levels of the SSL supply chain. One major issue is that data sheet information provided about packaged LEDs is usually insufficient and inconsistent among different LED vendors. Many data such as temperature sensitivity of different light output properties are provided to a limited extent only and usually by means of plots. Also, reported light output properties are typically rated for a junction temperature of 25 °C, which is obviously much below the junction temperature expected under real operating conditions. Even if “hot lumens” measured at a junction temperature of 85 °C this is not the actual operating temperature and there is little information about how such “hot lumen” tests are performed. The gap between and reported LED test data and actual operating conditions can be bridged by proper simulation models of LEDs and their environments. Such models should be accurate, hence capable of proper prediction of LED operation but simple enough to assure fast numerical simulations. However, LED integration do not get access to detailed LED information to perform those simulation at system level, thus perform reverse engineering which is time and cost consuming. A bridge, in the form of standardization, has to be established between the semiconductor industry and the LED component integrators. In order to achieve this, the following tools have to be provided: · Generic, multi-domain model of LED chips · Compact thermal model of the LED chips `environment (including the package and module assembly) · Modeling interface towards the luminaire The goal of the project is to develop a standardized method to create multi-domain LED compact models from testing data.

Industrial Mathematics in Europe

In this paper, we give an overview of the development of industrial mathematics in Europe. The advent of activities is in the 1970s, when, especially in Oxford, the potential of applications of mathematics was realized by Alan Tayler and co-workers, and the very successful study groups with industry were started. It led to discussions about European organisations such as ECMI, started in 1987, to a number of reports on mathematics in industry, to commercial institutes exploiting mathematics for industrial applications, and, finally, to a new organisation that was recently founded, EU-MATHS-IN. It is felt that it is important to share these experiences and activities with colleagues, anticipating that mathematics in industry will be a key enabling technology leading, in many respects, to a better world.

Preordering saddle-point systems for sparse LDLT factorization without pivoting

This paper focuses on efficiently solving large sparse symmetric indefinite systems of linear equations in saddle-point form using a fill-reducing ordering technique with a direct solver. Row and column permutations partition the saddle-point matrix into a block structure constituting a priori pivots of order 1 and 2. The partitioned matrix is compressed by treating each nonzero block as a single entry, and a fill-reducing ordering is applied to the corresponding compressed graph. It is shown that, provided the saddle-point matrix satisfies certain criteria, a block LDLT factorization can be computed using the resulting pivot sequence without modification. Numerical results for a range of problems from practical applications using a modern sparse direct solver are presented to illustrate the effectiveness of the approach.

Modeling liquid slugs accelerating in inclined conduits

In this article, we simulate traveling liquid slugs in conduits, as they may occur in systems carrying high-pressure steam. We consider both horizontal and inclined pipes in which the slug is accelerated by a suddenly applied pressure gradient, while at the same time, gravity and friction work in the opposite direction. This causes a steep slug front and an extended slug tail. The shapes of front and tail are of interest since they determine the forces exerted on bends and other obstacles in the piping system. The study also aims at improving existing one-dimensional (1D) models. A hybrid model is proposed that enables us to leave out the larger inner part of the slug. It was found that the hybrid model speeds up the two-dimensional (2D) computations significantly, while having no adverse effects on the shapes of the slugs front and tail.

Differential-Algebraic Equations

In this chapter, we introduce the differential algebraic equations which we abbreviate as DAEs. DAEs arise in a variety of applications such as modelling constrained multibody systems, electrical networks, aerospace engineering, chemical processes, computational fluid dynamics, gas transport networks, see [10–12, 35]. Therefore their analysis and numerical treatment plays an important role in modern mathematics.

Large Scale Problems

In this chapter, we illustrate the robustness of the IMOR method on large scale problems from real-life applications.

Index-aware Model Order Reduction

In this chapter, we discuss the index-aware model order reduction (IMOR) and its invariant the implicit-IMOR(IIMOR) method. We use the decoupled systems ( 3.2.11) and ( 3.7.1) to derive the IMOR and IIMOR method respectively.