1643372
Fault Tolerance by Transparent Replication for Distributed Ada 95
This paper presents the foundations of RAPIDS ("Replicated Ada Partitions In Distributed Systems"), an implementation of the Distributed Systems Annex E incorporating the transparent replication of partitions in distributed Ada 95 applications. RAPIDS is a replication manager for semi-active replication based on a piecewise deterministic computation model. It guarantees replica consistency for arbitrary Ada 95 partitions despite the inherent non-determinism of multitasking, offering k-resilient partitions. The RAPIDS prototype is implemented for the GNAT compiler and evolved from its PCS, Garlic.
62754021
Transparent replication for fault tolerance in distributed Ada 95
In this paper we present the foundations of RAPIDS ("Replicated Ada Partitions In Distributed Systems"), an implementation of the PCS supporting the transparent replication of partitions in distributed Ada 95 using semi-active replication. The inherently non-deterministic executions of multi-tasked partitions are modeled as piecewise deterministic histories. I discuss the validity and correctness of this model of computation and show how it can be used for efficient semi-active replication. The R APIDS prototype ensures that replicas of a partition all go through the same history and are hence consistent.
1084067
On exceptions as first-class objects in Ada 95
This short position paper argues that it might be beneficial to try to bring the exception model of Ada 95 more in-line with the object-oriented model of programming. In particular, it is felt that exceptions --- being such an important concept for the development of fault-tolerant software --- have deserved a promotion to first-class objects of the language. It is proposed to resolve the somewhat awkward dichotomy of exceptions and exception occurrences as it exists now in Ada 95 by treating exceptions as (tagged) types, and exception occurrences as their instances.
31197886
Object-Oriented Programming and Protected Objects in Ada 95
Integrating concurrent and object-oriented programming has been an active research topic since the late 1980s. The majority of approaches have taken a sequential object-oriented language and made it concurrent. A few approaches have taken a concurrent language and made it object-oriented. The most important of this latter class is the Ada 95 language which is an extension to the object-based concurrent programming language Ada 83. Arguably, Ada 95 does not fully integrate its models of concurrency and object-oriented programming. This paper discusses ways in which protected objects can be made more extensible.
196094
Integrating object-oriented programming and protected objects in Ada 95
Integrating concurrent and object-oriented programming has been an active research topic since the late 1980's. There is a now a plethora of methods for achieving this integration. The majority of approaches have taken a sequential object-oriented language and made it concurrent. A few approaches have taken a concurrent language and made it object-oriented. The most important of this latter class is the Ada 95 language, which is an extension to the object-based concurrent programming language Ada 83. Arguably, Ada 95 does not fully integrate its models of concurrency and object-oriented programming. For example, neither tasks nor protected objects are extensible. This article discusses ways in which protected objects can be made more extensible.
895386
Size Reduction and Partial Decoupling of Systems of Equations
A method is presented that reduces the number of terms of systems of linear equations (algebraic, ordinary and partial differential equations). As a byproduct these systems have a tendency to become partially decoupled and are more likely to be factorizable or integrable. A variation of this method is applicable to nonlinear systems. Modifications to improve efficiency are given and examples are shown. This procedure can be used in connection with the computation of the radical of a differential ideal (differential Grobner basis).
27997406
Forward Pruning and Other Heuristic Search Techniques in Tsume Go
Abstract G o T ools is the name of a computer program to analyse life and death fights in the game of go. First, a motivation for programing go is given. General aspects of the heuristic search performed in G o T ools are discussed. The absolute strength and the effect of forward tree pruning are tested in a competition between G o T ools and dan level human players. It is found that with a speed up of a factor of 30 the program still finds for 70% of the problems of a test set the correct first move. A suggestion is made to compare intelligence between contestants (in solving fully enclosed life/death problems) by comparing their relative increase in the time to solve problems with the increase of the difficulty of the problems. The rules of go are explained in the shortest possible form in Appendix A .
1220
A comparison of four approaches to the calculation of conservation laws
The paper compares computational aspects of four approaches to compute conservation laws of single differential equations or systems of them, ODEs and PDEs. The only restriction, required by two of the four corresponding computer algebra programs, is that each DE has to be solvable for a leading derivative. Extra constraints may be given. Examples of new conservation laws include non-polynomial expressions, an explicit variable dependence and conservation laws involving arbitrary functions. Examples involve the following equations: Ito, Liouville, Burgers, Kadomtsev-Petviashvili, Karney-Sen-Chu-Verheest, Boussinesq, Tzetzeica, Benney.
35976809
VIRTAB - Ein Programmsystem zur Generierung großer und reich strukturierter virtueller Tabellen und deren Aufteilung auf beschränkte Ausgabemedien
30440565
Ein optisches Meßsystem zur Echtzeitanalyse von Konturen mit der PLL-Schaltung
Mit einer einfachen analogen Phasenmestechnik, der PLL-Schaltung, lassen sich Phasenmessungen mit hoher Genauigkeit in Echtzeit realisieren. Insbesondere in optischen Messystemen, in denen mit einer Phasenbestimmung aus einem harmonischen Intensitatsmuster die gesuchte physikalische Mesgrose extrahiert werden mus, stellt die hier vorgestellte Methode eine lohnende Alternative zu den bekannten digitalen Auswertemethoden dar. Dabei entfallen sowohl die Beschrankung auf statische Phasenbilder sowie Problematiken bei der Phasenentfaltung. Die Konturmessung an einem Kalibrierkor per sowie ein Versuch zur Bestimmung des Kriechverhaltens eines PE-Schaumes werden als Beispielmessungen vorgestellt.