Object Programming in a Rule-Based Language with Strategies

Colloque avec actes et comité de lecture. internationale.International audienceThis paper presents a programming framework that combines the concepts of objects, rules and strategies, built as an extension of the rule-based language with strategies ELAN. This extension is implemented in a reflective way in ELAN itself and relies on the same formal semantics,namely the rewriting calculus

Rule Based Programming with Constraints & Strategies

Colloque avec actes et comité de lecture. internationale.International audienceWe present a framework for Rule Based Programming with Constraints and Strategies. It is based on an extension of the ELAN language, that provides an environment for specifying and prototyping deduction systems. The existence of strategies provides the user with the possibility to make choices, to act upon them, and to retract if needed using backtracking. To illustrate the framework, we formalise a planning problem, namely a controller for printing tasks, that shows how to combine rules, strategies and constraint solving on finite domains

Actions & Plans in ELAN

Colloque avec actes sans comité de lecture.ELAN is a declarative language based on rewriting logic. The ELAN language is based on labelled conditional rewrite rules and on strategies for controlling their application. ELAN provides a strategy language to control labelled rules. In this paper we show how to use the ELAN strategy language for planning. We describe how to encode situations and actions and take advantage of ELAN strategies to build plans. We give an example of our approach by describing an elevator controller

An algebraic semantics for objects in a rule-based language

Colloque avec actes et comité de lecture. internationale.International audienceL'acceptation et la participation à ce workshop sont soumises à l'envoi d'un abstract étendu de quelques page

Rules, strategies and objects in ELAN

Rapport interne.This paper gives an introduction to the ELAN rule-based programming language and presents the extension of the language with objects. The extension with objects is defined as a specific instance of the rewriting calculus, also called rho-calculus. This leads to an expressive programming framework that combines the concepts of objects, rules and strategies which has been prototyped in ELAN

Modelling Planning Problems with Rules & Strategies

Rapport interne.The ELAN system provides an environment for specifying and prototyping deduction systems in a language based on rewrite rules controlled by strategies. We design in ELAN a specific planning problem, namely a controller for printing tasks, by combining rules, strategies and constraint solving on finite domains

Total VOC reactivity in the planetary boundary layer: 2. A new indicator for determining the sensitivity of the ozone production to VOC and NO

A new indicator is proposed for determining if tropospheric ozone production in a specifiacr eai s limitedb yV OC or NOx.T he indicato1r 9= r•ø•C/•oød•Xes cribeths e ratio of the lifetimes of OH against the losses by reacting with VOC and NOx. Whereas •oøx• c anb e obtainebdy c onventionmale asurementthse, n ewp umpa ndp robeO H approach which is described in part one of this publication makes it now possible to obtain also ß_ov •o c ßI ndicator values above a thresholdv alue of 0.2 __+50 % are representativeo f NOx-saturatedc onditionsw here an increaseo f NOx emissionsc auses lower ozone production.F or valuesb elow 0.01 the ozone productioni s very insensitivet o changeso f VOC emissionsT. he robustnesso f this indicator againsts everalp arameters sucha s temperature,h umidity,p hotolysisa, nd initial ozone concentrationsis tested in a box model and comparedt o the robustnesso f other earlier proposedi ndicators.I n contrast to earlier proposed indicators, this new one is not based on photochemically producedl ong-liveds peciesb ut describest he instantaneousr egime of an air parcel. Three-dimensionasl imulations howst hat this indicator is quite successfuiln estimatingt he impact of increasedo r reducede missionso n the ozone concentrationsfo r each location in the modeling area. This will make it a very helpful tool for developing ozone abatement strategies

Total VOC reactivity in the planetary boundary layer: 1. Estimation by a pump and probe OH experiment

The reactivityo f hydroxyrl adical (OH) with total volatile organicc ompounds (VOC), Z kvoc[VOC ], is directly obtained in the planetary boundary layer (PBL). The method is basedo n a perturbationt echniquew here high initial OH concentrationsa re createdb yf lashp hotolysoisf ozonea nds ubsequerneta ctiono f O(•D) withH 20. Laserinduced fluorescence is used to measure the residual OH concentration at different time delays after the perturbation (<100 ms) and obtain a direct estimate of the OH lifetime rOH for different atmospheric conditions. For specific experimental conditions the transportb y the wind may be neglected,a nd the chemicalp rocessesg overningt he OH decaym ay be expressedb y a detailed box model. With a simple chemicale quation derived in this paper using roll and complementarym easurementso f CO, 03, and NOx, an in situ estimate of Z kvoc[VOC ] in the PBL is retrieved with an uncertainty of less than 20% in comparisont o the detailed box model calculationsT. his analysisi s applied to laboratory measurementsw ith three syntheticN Ox/VOC/O 3 gas mixtures,a nd the retrieved OH lifetimes and total VOC reactivitya re discusseda gainstm odel predictions

Results of the Calibration of the Delays of Earth Stations for TWSTFT Using the VSL Satellite Simulator Method

Two-way satellite time and frequency transfer (TWSTFT) is the most accurate and precise method of comparing two remote clocks or time scales. The accuracy obtained is dependent on the accuracy of the determination of the non-reciprocal delays of the transmit and the receive paths. When the same transponders in the satellite at the same frequencies are used, then the non-reciprocity in the Earth stations is the limiting factor for absolute time transfer

Preliminary Comparison of Two-Way Satellite Time and Frequency Transfer and GPS Common-View Time Transfer During the INTELSAT Field Trial

For a decade and a half Global Positioning System (GPS) common-view time transfer has greatly served the needs of primary timing laboratories for regular intercomparisons of remote atomic clocks. However, GPS as a one-way technique has natural limits and may not meet all challenges of the comparison of the coming new generation of atomic clocks. Two-way satellite time and frequency transfer (TWSTFT) is a promising technique which may successfully complement GPS. For two years, regular TWSTFT's have been performed between eight laboratories situated in both Europe and North America, using INTELSAT satellites. This has enabled an extensive direct comparison to be made between these two high performance time transfer methods. The performance of the TWSTFT and GPS common view methods are compared over a number of time-transfer links. These links use a variety of time-transfer hardware and atomic clocks and have baselines of substantially different lengths. The relative merits of the two time-transfer systems are discussed