Rocky Dunlap

Performance of Full Text Search in Structured and Unstructured Peer-to-Peer Systems

While structured P2P systems (such as DHTs) are often regarded as an improvement over unstructured P2P systems (such as super-peer networks) in terms of routing efficiency, it is not clear which architecture is better for full text search. This paper provides a quantitative comparison of full text keyword search in structured and unstructured P2P systems. We examine three techniques (and optimizations to those techniques) proposed in the literature: using a DHT along with inverted lists and Bloom filters; using a super-peer network; and using a random walk over an unstructured network. We use real Web documents and user queries to measure the cost for both document publishing and query processing, in terms of bandwidth and response time. Our results show that all three techniques use roughly the same bandwidth to process queries (with the super-peer technique having a slight edge). The structured network provides the best response time (30 percent better than a super-peer network), but has a high cost of document publishing, using six times as much bandwidth as the super-peer system. The random walk technique requires no publishing, but has a very long response time unless multiple random walks operate in parallel.

A feature model of coupling technologies for Earth System Models

Couplers that link together two or more numerical simulations are well-known abstractions in the Earth System Modeling (ESM) community. In the past decade, reusable software assets have emerged to facilitate scientists in implementing couplers. While there is a large amount of overlap in the features supported by software coupling technologies, their implementations differ significantly in terms of both functional and non-functional properties. Using a domain analysis method called feature analysis, we explore the spectrum of features supported by coupling technologies used to build todays production ESMs.

Second Workshop on Coupling Technologies for Earth System Models

In final form 22 May 2013 ©2014 American Meteorological Society T he Second Workshop on Coupling Technologies for Earth System Models (CW2013) continued the momentum of the first workshop held two years prior (Valcke and Dunlap 2011a,b) by bringing together researchers and practitioners from over 20 institutions across the globe. Coupling technologies are software packages designed to instantiate a system of interacting components by offering support for parallel data exchange, repartitioning of distributed data structures across processor sets, grid interpolation and remapping, control f low management, and other utilities. The goals of the workshop were to update participants on recent developments in coupling technologies, share experiences deploying existing coupling infrastructure into new contexts, discuss common challenges and goals, and identify possible avenues for community convergence via software interoperability, benchmarking, and sharing infrastructure. The three-day workshop included 31 talks in five major sessions: coupling technologies overviews and recent developments, experience reports, interoperability (I/O), benchmarking, and performance of new and emerging architectures. After hearing all talks, participants discussed common themes that emerged during the workshop and identified possible next steps. The workshop program including presentation slides and abstracts are available on the CW2013 wiki (located at https:// wiki.cc.gatech.edu/CW2013).

Managing Software Complexity and Variability in Coupled Climate Models

Coupled climate models exhibit scientific, numerical, and architectural variability. This variability introduces requirements that give rise to complexity. However, techniques exist that can tame this complexity; one such technique is feature analysis. As climate model fidelity and complexity increase, the climate-modeling community should adopt a systematic way to deal with software variability.

Offshore wind metadata management

Offshore wind energy is gaining more and more attention from industry and research community due to its high potential in producing green energy and lowering price on electricity consumption. However, offshore wind is facing many challenges, and hence it is still expensive to install in large scale. It therefore needs to be considered from different aspects of technologies in order to overcome these challenges. One of the problems of the offshore wind is that information comes from different sources with diversity in types and format. Besides, there are existing wind databases that should be utilised in order to enrich the knowledge base of the wind domain. This paper describes an approach to managing offshore wind metadata effectively using semantic technologies. An offshore wind ontology has been developed. The semantic gap between the developed ontology and the relational database is investigated. A prototype system has been developed to demonstrate the use of the ontology.