Browsing University of Hertfordshire by Author "Christianson, B."

Now showing items 81-100 of 144

    • A Note About the Semantics of Delegation 

      Crispo, B.; Christianson, B. (ACM Press, 1999)
      In many applications, mobile agents are used by a client to delegate a task. This task is usually performed by the agent on behalf of the client, by visiting various service provider's sites distributed over a network. ...

    • Optimization and automatic differentiation in Ada : some practical experience 

      Bartholomew-Biggs, M.; Bartholomew-Biggs, Lynda; Christianson, B. (1994)
      This paper describes an investigation into the performance of three Ada packages for automatic differentiation. Two of these implement the forward accumulation approach while the third employs reverse accumulation. Each ...

    • Optimizing Preventive Maintenance Models 

      Bartholomew-Biggs, M.; Christianson, B.; Zuo, M. (2006)
      We deal with the problem of scheduling preventive maintenance (PM) for a system so that, over its operating life, we minimize a performance function which reflects repair and replacement costs as well as the costs of the ...

    • Optimizing Preventive Maintenance Models. 

      Christianson, B.; Bartholomew-Biggs, M. (2005)
      We consider the problem of scheduling preventive maintenance so as to minimize the expected total repair and replacement costs over the lifetime of a system. Our AD-based approach involves some non-standard features, such ...

    • Optimizing real-time transport protocols 

      Christianson, B. (University of Hertfordshire, 1990)
      A real-time transport protocol must trade delay against loss. Here we consider the problem of minimizing the mean transport delay subject to a given maximum acceptable loss rate. This form of the trade-off is appropriate ...

    • Oxford Blues: the search for the origins of the lay bachelors' hood 

      Christianson, B. (2003)
      By way of introduction to his discussion of the system of academic dress at the University of Oxford, Franklyn writes: "At the present day, although Oxford, Southampton, and Hull undoubtedly possess the most beautiful, ...

    • A Performance Comparison of Wireless Ad Hoc Network Routing Protocols under Security Attack 

      Bo, S.M.; Xiao, Hannan; Adereti, A.; Malcolm, J.; Christianson, B. (Institute of Electrical and Electronics Engineers (IEEE), 2007)

    • Pico without public keys 

      Christianson, B.; Stajano, Frank; Lomas, Mark; Jenkinson, Graeme; Jeunese, Payne; Stafford-Fraser, Quentin; Spencer, Max (Springer Nature, 2015-11-25)
      Pico is a user authentication system that does not require remembering secrets. It is based on a personal handheld token that holds the user’s credentials and that is unlocked by a “personal aura” generated by digital ...

    • Pictures Can’t Lie under Oath 

      Christianson, B.; Malcolm, J.; Robinson, B. (2000)
      Because image manipulation by computer is so easy, it is hard to be sure that an image was indeed created at the date, time and place claimed, and that it has not been altered since. To gain this confidence requires a ...

    • The positive fixed points of Banach lattices 

      Christianson, B. (1989)
      Let Z be a Banach lattice endowed with positive cone C and an order-continuous norm j.j . Let G be a left-amenable semigroup of positive linear endomorphisms of Z . Then the positive fixed points Co of Z under G form a ...

    • Positive fixed points of lattices under semigroups of positive linear operators 

      Christianson, B. (1995)
      Let Z be a Banach lattice endowed with positive cone C and an order-continuous norm ||.||. Let G be a semigroup of positive linear endomorphisms of Z...

    • Positive fixed points of lattices under semigroups of positive linear operators 

      Christianson, B. (University of Hertfordshire, 1993)
      Let Z be a Banach lattice endowed with positive cone C and an order-continuous norm [...]. Let G be a semigroup of positive linear endomorphisms of Z. We seek conditions on G sufficient to ensure that the positive fixed ...

    • Preface 

      Christianson, B.; Malcolm, J.; Crispo, B.; Stajano, F. (2011)
      This volume collects the revised proceedings of the 19th International Security Protocols Workshop, held in Sidney Sussex College, Cambridge, March 2011

    • Preface: Special issue dedicated to Andreas Griewank on the occasion of his 60th birthday Preface 

      Christianson, B.; Naumann, Uwe; Utke, Jean; Walther, Andrea (2012)

    • Public-Key Crypto-systems Using Symmetric-Key Crypto-algorithms 

      Christianson, B.; Crispo, B.; Malcolm, J. (2001)
      The prospect of quantum computing makes it timely to consider the future of public-key crypto-systems. Both factorization and discrete logarithm correspond to a single quantum measurement, upon a superposition of candidate ...

    • A Purchase Protocol with Live Cardholder Authentication for Online Credit Card Payment 

      Xiao, Hannan; Christianson, B.; Zhang, Y. (Institute of Electrical and Electronics Engineers (IEEE), 2008)

    • A Purchase Protocol with Multichannel Authentication 

      Xiao, Hannan; Christianson, B.; Zhang, Ying (2009)
      While online shopping are becoming more accepted by people in modern life, cardholders are more concerned about card fraud and the lack of cardholder authentication in the current online credit card payment. This paper ...

    • A Purple Passion? : Queen's College Oxford and the Blood of the Lord 

      Christianson, B. (2012)
      The Queen’s College Oxford was founded in 1341 ‘under the name of the Hall of the Queen’s scholars of Oxford’ by the endowment of Robert de Eglesfield. The queen in question was Queen Philippa of Hainault, consort of King ...

    • Recognizing Facial Expressions : A Comparison of Computational Approaches 

      Shenoy, A.; Gale, T.M.; Davey, N.; Christianson, B.; Frank, R. (2008)
      Recognizing facial expressions are a key part of human social interaction,and processing of facial expression information is largely automatic, but it is a non-trivial task for a computational system. The purpose of this ...

    • Reducing the Branch Power Cost In Embedded Processors Through Static Scheduling, Profiling and SuperBlock Formation 

      Hicks, M.; Egan, C.; Christianson, B.; Quick, P. (2006)
      Dynamic branch predictor logic alone accounts for approximately 10% of total processor power dissipation. Recent research indicates that the power cost of a large dynamic branch predictor is offset by the power savings ...