Total algorithms

We define the notion of total algorithms for networks of processes. A total algorithm enforces that a "decision" is taken by a subset of the processes, and that participation of all processes is required to reach this decision. Total algorithms are an important building block in the design of distributed algorithms. For some important network control problems it can be shown that an algorithm solving it is necessarily total, and that any total algorithm can solve the problem. We study some total algorithms for a variety of network topologies. Constructions are shown to derive algorithms for Mutual Exclusion, Election, and Distributed Infirnum Approximation from arbitrary total algorithms. The paper puts many results and paradigms about designing distributed algorithms in a general framework. This report oulines several other works of the author. Total algorithms, their properties, and some additional examples, as well as traversal algorithms and the time complexity of distributed algorithms are studied in [Tel94, Chap.6]. The construction of algorithms for distributed infirnum approximation is treated in [CBT94, Tel86] and [Tel91, Sec. 4.1]

The derivation of distributed termination detection algorithms from garbage collection schemes

It is shown that the termination detection problem for distributed computations can be modelled as an instance of the garbage collection problem. Consequently, algorithms for the termination detection problem are obtained by applying transformations to garbage collection algorithms. The transformation can be applied to collectors of the "mark-and-sweep" type as well as to reference counting garbage collectors. As examples, the scheme is used to transform the distributed reference counting protocol of Lermen and Maurer, the weighted reference counting protocol, the local reference counting protocol, and Ben-Ari's mark-and-sweep collector into termination detection algorithms. Known termination detection algorithms as well as new variants are obtained

Optimal synchronization of ABD networks

We present in this paper a simple and efficient synchronizer algorithm for Asynchonous Bounded Delay Networks. In these networks each processor has a local clock, and the message delay is bounded by a known constant. The algorithm improves on an earlier synchronizer for this network model, presented by Cou et al. Moreover, using a mathematical model for this type of synchronizer, we show that the round time of new synchronizer is optimal

A chaotically driven model climate: extreme events and snapshot attractors

In a low-order chaotic global atmospheric circulation model the effects of deterministic chaotic driving are investigated. As a result of driving, peak-over-threshold type extreme events, e. g. cyclonic activity in the model, become more extreme, with increased frequency of recurrence. When the characteristic time of the driving is comparable to that of the undriven system, a resonance effect with amplified variance shows up. For very fast driving we find a reduced enhancement of variance, which is also the case with white noise driving. Snapshot attractors and their natural measures are determined as a function of time, and a resonance effects is also identified. The extreme value statistics of group maxima is found to follow a Weibull distribution

An all-in-one web tool to apply CTD quality control, format data, and generate metadata under SeaDataNet criteria

Professional data centres of the Pan-European region active in marine data collection, in particular National Oceanographic Data Centres (NODCs), routinely share diverse datasets through SeaDataNet, a distributed Marine Data Infrastructure. This network provides on-line integrated databases of standardized quality. Sharing marine data through SeaDataNet is an optimal way of ensuring FAIR principles: Findable, Accessible, Interoperable and Reusable. However, submission of data to this infrastructure demands a set of technical tasks that cover quality control processing, adoption of common vocabularies, implement file format standards and preparation of associated metadata. Although common software tools are made available to NODCs to facilitate data and metadata preparation (see https://www.seadatanet.org/Software) these tasks continuous to be complex and time-consuming. For example, the technician must use MIKADO software to generate INSPIRE-complaint metadata and adopt SeaDataNet Common Vocabularies; NEMO software to transform the original file to a common data transport format; and OCTOPUS software to check the compliance of a file. Additional software must be used to quality check and properly flag each individual record.En prens

Simplifying quality control and standardization of CTD data under SeaDataNet requirements

Sharing marine data through SeaDataNet infrastructure ensures preservation and promotes reusability. Submission of data to this infrastructure demands a set of technical tasks that cover quality control processing, adoption of common vocabularies, implement le format standards and preparation of associated metadata. Although common software tools are made available to Data Centres and/or End Users to facilitate data and metadata preparation, these tasks continuous to be complex and time-consuming. To speed-up this process, a Python-Flask web application is presented here to quality check and create metadata and data according to SeaDataNet requirements. The web tool focuses on CTD vertical pro les, although code could be easily adapted to process other type of records