Strong normalisation in the π-calculus

We introduce a typed π-calculus where strong normalisation is ensured by typability. Strong normalisation is a useful property in many computational contexts, including distributed systems. In spite of its simplicity, our type discipline captures a wide class of converging name-passing interactive behaviour. The proof of strong normalisability combines methods from typed λ-calculi and linear logic with process-theoretic reasoning. It is adaptable to systems involving state, non-determinism, polymorphism, control and other extensions. Strong normalisation is shown to have significant consequences, including finite axiomatisation of weak bisimilarity, a fully abstract embedding of the simply typed λ-calculus with products and sums and basic liveness in interaction. Strong normalisability has been extensively studied as a fundamental property in functional calculi, term rewriting and logical systems. This work is one of the first steps to extend theories and proof methods for strong normalisability to the context of name-passing processes.     

Factors affecting the dynamics of a π‐cell (Invited Paper)

Abstract— The basic factors related to the dynamics of a π‐cell device are reviewed. Specifically, the director dynamics are studied for the case of a periodic drive voltage that is sometimes referred to as “impulse drive.” It is found for this type of drive waveform the desired bend state is more stable against the twisting effect of transverse electric fields found in AMLCD devices. This effect causes the reduction in light transmission due to “impulse drive” to be smaller in π‐cell devices than is expected to be found in other AMLCD modes.     

Low voltage fast response display using dual π‐cells with quarter‐wave thickness

In this paper, a design for a fast response display consisting of dual π‐cells is investigated. The thickness of each liquid crystal cell layer is only half of a single LC cell device with the same retardation change, which results in about one quarter of the response time for a single π‐cell device. While this result is obviously anticipated, an additional advantage is that a good viewing angle can be achieved by using negative C plates, which allows a lower cost device with a more uniform black state across the area of the display than the case of a single cell compensated by a discotic compensator. We also propose a solution to solve parallax issue from two‐layer structure of liquid crystal cell, and it opens a window of opportunity for a device with two‐layer structure.     

Probabilistic π-Calculus and Event Structures

This paper proposes two semantics of a probabilistic variant of the π-calculus: an interleaving semantics in terms of Segala automata and a true concurrent semantics, in terms of probabilistic event structures. The key technical point is a use of types to identify a good class of non-deterministic probabilistic behaviours which can preserve a compositionality of the parallel operator in the event structures and the calculus. We show an operational correspondence between the two semantics. This allows us to prove a “probabilistic confluence” result, which generalises the confluence of the linearly typed π-calculus.     

EO characteristics for a photoaligned VA‐1/4 π cell on a photopolymer layer

The generation of a liquid‐crystal (LC) tilt angle on a copolymer with chalconyl and cholesteryl moiety characteristics was performed, and the electro‐optical (EO) performance of the photoaligned vertical‐alignment (VA) 1/4 π cell by polarized UV exposure on a homeotropic photopolymer surfaces was studied. The LC tilt angles decreased as UV exposure time increased on the copolymer surfaces. A tilt angle of 87° in NLC was observed with an UV exposure of 3 min on the photoalignment‐2 surface. The LC tilt angle is attributed to increased chalcone moiety with increasing UV exposure time. Excellent voltage‐transmittance (V‐T) curves of the photoaligned VA 1/4 π cell by polarized UV exposure on the photopolymer surface for 3 min containing a cholesteryl moiety of 8% were obtained. The V‐T and response‐time characteristics can be improved by the presence of a cholesteryl moiety in the photopolymer.     

A Proof Search Specification of the π-Calculus

We present a meta-logic that contains a new quantifier (for encoding “generic judgments”) and inference rules for reasoning within fixed points of a given specification. We then specify the operational semantics and bisimulation relations for the finite π-calculus within this meta-logic. Since we restrict to the finite case, the ability of the meta-logic to reason within fixed points becomes a powerful and complete tool since simple proof search can compute this one fixed point. The quantifier helps with the delicate issues surrounding the scope of variables within π-calculus expressions and their executions (proofs). We shall illustrate several merits of the logical specifications we write: they are natural and declarative; they contain no side conditions concerning names of variables while maintaining a completely formal treatment of such variables; differences between late and open bisimulation relations are easy to see declaratively; and proof search involving the application of inference rules, unification, and backtracking can provide complete proof systems for both one-step transitions and for bisimulation.     

A non‐smooth lower bound on ν

A non‐smooth optimization technique to directly compute a lower bound on the skew structured singular value ν is developed. As corroborated by several real‐world challenging applications, the proposed technique can provide tighter lower bounds when compared with currently available techniques. Moreover, in many cases, the determined lower bound equals the true value of ν. Thanks to the efficiency of the non‐smooth technique, the algorithm can be applied to problems involving even a significant number of uncertain parameters. Another appealing feature of the proposed non‐smooth approach is that the dimension of repeated scalar uncertainties in the overall structured uncertainty matrix has little impact on the computational time. The technique can be used to compute a lower bound on the structured singular value μ as well. Copyright © 2012 John Wiley & Sons, Ltd.     

A generalized χ 2 divergence for multisource information fusion and its application in fault diagnosis

Dempster–Shafer theory is invaluable for handing uncertain problems in multisource information fusion field. But how to fuse highly conflicting information remains a pending issue. To deal with the issue, we propose a novel reinforced belief ${\chi }^2$ divergence measure (named as $\mathrm{??}{\chi }^2$ divergence) to calculate the conflict degree between evidence. The proposed $\mathrm{??}{\chi }^2$ divergence comprehensively considers the effects of the single-element subset and the multielement subset. In addition, the $\mathrm{??}{\chi }^2$ divergence has been proved to be a bounded, nondegenerate, and symmetrical divergence measure. Then, we design a new $\mathrm{??}{\chi }^2$ divergence-based multisource information fusion method. This method combines information volume weights and supports degree weights to modify the evidence before fusion. Finally, an application for fault diagnosis is provided to show that the proposed method is superior to other existing methods.