A Lifetime-based Garbage Collector for LISP Systems on General-Purpose Computers

Garbage collector performance in LISP systems on custom hardware has been substantially improved by the adoption of lifetime-based garbage collection techniques. To date, however, successful lifetime-based garbage collectors have required special-purpose hardware, or at least privileged access to data structures maintained by the virtual memory system. I present here a lifetime-based garbage collector requiring no special-purpose hardware or virtual memory system support, and discuss its performance.

Computational modelling of multi-physics processes on high performance parallel computer systems

The demands of the process of engineering design, particularly for structural integrity, have exploited computational modelling techniques and software tools for decades. Frequently, the shape of structural components or assemblies is determined to optimise the flow distribution or heat transfer characteristics, and to ensure that the structural performance in service is adequate. From the perspective of computational modelling these activities are typically separated into: • fluid flow and the associated heat transfer analysis (possibly with chemical reactions), based upon Computational Fluid Dynamics (CFD) technology • structural analysis again possibly with heat transfer, based upon finite element analysis (FEA) techniques.

Emerging Technologies

This book, written when Walker was Visiting Professor at the Technical University Munich in 2011, describes his research on the effects of digital technology on architectural design and construction, and on the development of ‘digital craft’. The primary example given is The Swarm, a digitally designed and manufactured pavilion, produced with students while Walker was at TU Munich. It now stands outside the Bayerischen Architektenkammer (Bavarian Chamber of Architects) in Munich. Through such research-by-design, Walker asks larger questions: what can designers craft without a master craftsman’s skills, and how can craft skills be recovered through digital fabrication? Another example in the book is the Swoosh Pavilion, one of two public-space-scale architectural pavilion prototypes Walker developed between 2008 and 2009 at the Architectural Association (AA), using applied digital modelling and CNC techniques to investigate methods of teaching and testing digital processes through making. Swoosh (2008) and a second AA pavilion, Driftwood (2009), were discussed by Walker and Martin Self, his co-investigator, in ‘Fractal, bad hair, Swoosh and Driftwood pavilions of Intermediate Unit 2, 2006–2009’, published in the AD reader, Manufacturing the Bespoke (2012), which includes essays by well-known critics and designers such as Mathias Kohler and Michael Stacey. Both AA pavilions were sponsored by FinnForest Merk, Arup, HOK and Building Design Magazine, and were seen by large international audiences in Bedford Square, London during the 2008–9 ‘AA Projects Review’ shows. The book Making Pavilions (Walker and Self, AA Agenda No. 9, Architectural Association Press, 2011) also discusses their work over seven years of teaching at the Architectural Association. At the same time, Walker collaborated on a series of Serpentine pavilions, commissioned annually by the Serpentine Gallery, London, co-designing these experimental structures with internationally renowned architects Daniel Libeskind, Oscar Niemeyer, Toyo Ito and Alvaro Siza.

Using a prioritized MAC protocol to execute the database operation join in networked embedded computer systems

Database query languages on relations (for example SQL) make it possible to join two relations. This operation is very common in desktop/server database systems but unfortunately query processing systems in networked embedded computer systems currently do not support this operation; specifically, the query processing systems TAG, TinyDB, Cougar do not support this. We show how a prioritized medium access control (MAC) protocol can be used to efficiently execute the database operation join for networked embedded computer systems where all computer nodes are in a single broadcast domain.