Regular Trace Event Structures

We propose trace event structures as a starting point for constructing effective branching time temporal logics in a non-interleaved setting. As a first step towards achieving this goal, we define the notion of a regular trace event structure. We then provide some simple characterizations of this notion of regularity both in terms of recognizable trace languages and in terms of finite 1-safe Petri nets

Methods of shell cleaning and polishing

From very early time in the history of mankind molluscan shells have been used for various purposes. Primitive man who lived in the cave used shells as ornaments, vessels and weapons. Ancient tribes used conch and triton shells as trumpets to summon people

A green Hibiscus cannabinus oil emollient cream for potential topical applications

A green emollient cream with Hibiscus cannabinus seed oil and an alkyl polyglucoside surfactant has been formulated. It can serve as biological alternatives to synthetic formulations that normally incorporate chemical constituents as surfactants and stabilizers mainly to increase consumer compliance in terms of textural and visual aesthetics. FAME analysis of the oil showed the presence octanoic and decanoic acids. The cream after formulation and ultrasonication, presented a smooth and soft appearance with visual and textural appeal. It showed a mean particle size of 138 nm with a zeta potential of -59.2 mV and an electrophoretic mobility of -0.000459 cm2/Vs. Its SEM image projected well dispersed oil globules in water. FTIR spectrum showed extensive hydrogen bonding. Accelerated stability tests under conditions of freeze thawing, heating cooling and centrifugation revealed no cracking, creaming or phase separation. Similar results were observed during the shelf life studies. It is concluded that this Hibiscus cannabinus cream can be utilized as an emollient base for loading cosmopharmaceutic ingredients for their topical delivery, without any toxicity concerns, as it is formulated from completely natural constituents

Product interval automata

We identify a subclass of timed automata called product interval automata and develop its theory. These automata consist of a network of timed agents with the key restriction being that there is just one clock for each agent and the way the clocks are read and reset is determined by the distribution of shared actions across the agents. We show that the resulting automata admit a clean theory in both logical and language theoretic terms. We also show that product interval automata are expressive enough to model the timed behaviour of asynchronous digital circuits

An expressively complete linear time temporal logic for Mazurkiewicz traces

A basic result concerning LTL, the propositional temporal logic of linear time, is that it is expressively complete; it is equal in expressive power to the first order theory of sequences. We present here a smooth extension of this result to the class of partial orders known as Mazurkiewicz traces. These partial orders arise in a variety of contexts in concurrency theory and they provide the conceptual basis for many of the partial order reduction methods that have been developed in connection with LTL-specifications. We show that LTrL, our linear time temporal logic, is equal in expressive power to the first order theory of traces when interpreted over (finite and) infinite traces. This result fills a prominent gap in the existing logical theory of infinite traces. LTrL also provides a syntactic characterisation of the so-called trace consistent (robust) LTL-specifications. These are specifications expressed as LTL formulas that do not distinguish between different linearisations of the same trace and hence are amenable to partial order reduction methods

Comparison of added mass coefficients for a floating tanker evaluated by conformal mapping and boundary element methods

One of the important parameters needed to model ship motions in a seaway is the added mass matrix of the hull. Current state-ofthe- art boundary element methods routinely evaluate the 6 x 6 added mass matrices as part of the radiation problem solution. These developments have largely superseded conventional approaches to sectional added mass evaluation using conformal mapping techniques. However, conformal mapping techniques are still attractive in terms of their mathematical explicitness and computational simplicity. The recurrent form of Bieberbach Method of conformal mapping was developed for mapping the exterior of a closed curve i.e. the two-dimensional ship cross section and its mirror image, into the exterior of the circle oscillating vertically at free surface and to compute the added mass coefficients. By incorporating a strip theory approximation the added mass coefficients of a three dimensional structure can be estimated from its two-dimensional section coefficients at different drafts. In this paper we have applied this method to calculate the heave, pitch and heave induced pitch added mass coefficients of a tanker. The applicability of these conformal mapping techniques to floating platforms under consideration is discussed, by comparing the results with state-of-the-art industry standard boundary element methods, AQWA and SESAM

Elementary Transition Systems and Refinement

The model of Elementary Transition Systems has been introduced by the authors as an abstraction of Elementary Net Systems - with a formal embedding in terms of a categorical coreflection, keeping behavioural information like causality, concurrency and conflict, but forgetting the concrete programming of a particular behaviour over an event set using conditions. In this paper we give one example of the advantages of ETS over ENS, - the definition of local state refinement. We show that the well known problems in understanding within nets the simple notion of syntactic substitution of conditions by (sub) nets behaviourally, - these problems seem to disappear when moving to the more abstract level of ETS. Formally, we show that the ETS-version of condition-substitution does satisfy nice and natural properties, e.g., projection and compositionality results w.r.t. a standard notion of transition system morphisms

Transition Systems, Event Structures and Unfoldings

Elementary transition systems were introduced by the authors in DAIMI PB-310. They were proved to be, in a strong categorical sense, the transition system version of elementray net systems. The question arises whether the notion of a region and the axioms (mostly based on regions) imposed on ordinary transition systems to obtain elementray net systems. Stated differently, one colud ask whether elementray transition systems could also play a role in characterizing other models of concurrency. We show here that by smoothly stengthening the axioms of elementary transition systems one obtains a subclass called occurrence transitions systems which turn out to be categorically equivalent to the well-known model of concurrency called prime event structures. Next we show that occurrence transition systems are to elementry transition systems what occurrence nets are to elementary nets systems. We define an ''unfold'' operation on elementry transition systems which yields occurrence transistion systems. We then prove that this operation uniquely extends to a functor which is the right adjoint to the inclusion functor from (the full subcategory of) occurrence transition systems to (the category of) elementary transition systems. Thus the results of this paper also show that the semantic theory of elementray net systems has a nice counterpart in the more abstract world of transition systems

Elementary Transition Systems and Refinement

The model of Elementary Transition Systems has been introduced by the authors as an abstraction of Elementary Net Systems - with a formal embedding in terms of a categorical coreflection, keeping behavioural information like causality, concurrency and conflict, but forgetting the concrete programming of a particular behaviour over an event set using conditions. In this paper we give one example of the advantages of ETS over ENS, - the definition of local state refinement. We show that the well known problems in understanding within nets the simple notion of syntactic substitution of conditions by (sub) nets behaviourally, - these problems seem to disappear when moving to the more abstract level of ETS. Formally, we show that the ETS-version of condition-substitution does satisfy nice and natural properties, e.g., projection and compositionality results w.r.t. a standard notion of transition system morphisms