ASCOT: solving the kinetic equation of minority particle species in tokamak plasmas

A comprehensive description of methods, suitable for solving the kinetic equation for fast ions and impurity species in tokamak plasmas using Monte Carlo approach, is presented. The described methods include Hamiltonian orbit-following in particle and guiding center phase space, test particle or guiding center solution of the kinetic equation applying stochastic differential equations in the presence of Coulomb collisions, neoclassical tearing modes and Alfv\'en eigenmodes as electromagnetic perturbations relevant to fast ions, together with plasma flow and atomic reactions relevant to impurity studies. Applying the methods, a complete reimplementation of the well-established minority species code ASCOT is carried out as a response both to the increase in computing power during the last twenty years and to the weakly structured growth of the code, which has made implementation of additional models impractical. Also, a benchmark between the previous code and the reimplementation is accomplished, showing good agreement between the codes.Comment: 13 pages, 9 figures, submitted to Computer Physics Communication

Second NASA Technical Interchange Meeting (TIM): Advanced Technology Lifecycle Analysis System (ATLAS) Technology Tool Box (TTB)

The Advanced Technology Lifecycle Analysis System (ATLAS), a spreadsheet analysis tool suite, applies parametric equations for sizing and lifecycle cost estimation. Performance, operation, and programmatic data used by the equations come from a Technology Tool Box (TTB) database. In this second TTB Technical Interchange Meeting (TIM), technologists, system model developers, and architecture analysts discussed methods for modeling technology decisions in spreadsheet models, identified specific technology parameters, and defined detailed development requirements. This Conference Publication captures the consensus of the discussions and provides narrative explanations of the tool suite, the database, and applications of ATLAS within NASA s changing environment

RippleNet: Propagating User Preferences on the Knowledge Graph for Recommender Systems

To address the sparsity and cold start problem of collaborative filtering, researchers usually make use of side information, such as social networks or item attributes, to improve recommendation performance. This paper considers the knowledge graph as the source of side information. To address the limitations of existing embedding-based and path-based methods for knowledge-graph-aware recommendation, we propose Ripple Network, an end-to-end framework that naturally incorporates the knowledge graph into recommender systems. Similar to actual ripples propagating on the surface of water, Ripple Network stimulates the propagation of user preferences over the set of knowledge entities by automatically and iteratively extending a user's potential interests along links in the knowledge graph. The multiple "ripples" activated by a user's historically clicked items are thus superposed to form the preference distribution of the user with respect to a candidate item, which could be used for predicting the final clicking probability. Through extensive experiments on real-world datasets, we demonstrate that Ripple Network achieves substantial gains in a variety of scenarios, including movie, book and news recommendation, over several state-of-the-art baselines.Comment: CIKM 201

Goldfield Studies

The dialogue within this essay serves as a response to the series, Goldfield Studies, a work itself prompted by the history and landscape of this eponymous region of Victoria, Australia. The imagery produced takes the form of paired and multiple still photographs and a digital video sequence, displayed in triple-projection. The discussion is framed by the artist’s introduction, which defines the project as a critical consideration of cultural memory in relation to the opposing perspectives of indigenous and colonial settler narratives, pastoral landscape representations, folklore and myth. A collaborative dialogue between an artist and art historian who share common research concerns follows the introduction. The conversation that ensues addresses the work’s multiple access points while questioning the ontological status of photographic representation and its subsequent relation to metaphysical questions of Being. The essay concludes with a response by the artist, furthering the participatory nature of the dialogue in relation to experience and representation

Data Model for Storage and Retrieval of Legislative Documents in Digital Libraries Using Linked Data

Many countries have provided online access to some types of legislative documents by subject, keywords or date. Nevertheless, the possibility of querying historical versions of the documents is usually an uncommon feature. The dispersion of laws and other legislative documents and their continuous changes make difficult the generation and querying of valid legislative information at a given date. Furthermore, the ripple effect of modifications such as updates, insertions or derogations affecting the entire body of a law or part of it is not always visible for the citizens who are looking for legislative information. Some issues related to change management of legislative documents can be identified: how to apply the history of changes to a version of a legislative document to obtain a new version, and what type of data model might be better to satisfy temporal queries, to store new versions of documents or to obtain them dynamically. The access to all versions of a document and its fragments is important in legislative queries to be sure which law was in force to apply when a case happened. Law documents are produced and stored in information systems with different data models to access and retrieve information about them in a large-scale manner, but most of them do not have law change management functions. Web standards, such as XML, XSLT and RDF, facilitate the separation between content, presentation and metadata, thus contributing to a better annotation and exploitation of information from these documents and their fragments to improve the historical queries and the version generation of legislative documents. This paper presents a proposal of a data model for storage and retrieval of different versions of legislative documents using Linked Data, a method of publishing structured interlinked data, for managing relations between legislative documents and its changes. Document structures, changes to legislation, metadata, requirements of historical queries are analyzed in this work. Furthermore, the proposed model facilitates historical querying of legislative documents and consolidation procedures, allowing update relationships between documents and fragments without changes on the original documents. The model has been tested with Ecuadorian laws, but it could be used for law systems of other countries because the model is independent of the legislative framework.This work has been partially supported by the Prometeo Project by SENESCYT, Ecuadorian Government

Seeing the invisible: from imagined to virtual urban landscapes

Urban ecosystems consist of infrastructure features working together to provide services for inhabitants. Infrastructure functions akin to an ecosystem, having dynamic relationships and interdependencies. However, with age, urban infrastructure can deteriorate and stop functioning. Additional pressures on infrastructure include urbanizing populations and a changing climate that exposes vulnerabilities. To manage the urban infrastructure ecosystem in a modernizing world, urban planners need to integrate a coordinated management plan for these co-located and dependent infrastructure features. To implement such a management practice, an improved method for communicating how these infrastructure features interact is needed. This study aims to define urban infrastructure as a system, identify the systematic barriers preventing implementation of a more coordinated management model, and develop a virtual reality tool to provide visualization of the spatial system dynamics of urban infrastructure. Data was collected from a stakeholder workshop that highlighted a lack of appreciation for the system dynamics of urban infrastructure. An urban ecology VR model was created to highlight the interconnectedness of infrastructure features. VR proved to be useful for communicating spatial information to urban stakeholders about the complexities of infrastructure ecology and the interactions between infrastructure features.https://doi.org/10.1016/j.cities.2019.102559Published versio

Rewilding with the beaver in Portugal: an economic analysis

Rivers and streams in Portugal are in poor ecological condition. River restoration programs are therefore seen as essential. It is well established that the beaver is an important tool for improving the ecological state of fresh water habitats. This study aims to determine the potential to use beavers has a tool in future river restoration programs. The work compares, from an economic and environmental perspective, an active management approach in the form of traditional river restoration actions and a passive management strategy in the form of beaver reintroduction. First, a brief overview of the conditions for the European beaver to return to the Portuguese landscape is presented. Second, an economic estimation based on the potential to save on habitat restoration costs, beaver management expenditures and the funds required for a reintroduction program is provided. These estimates are compared with the APA 2018-2020 river restoration program. Third and lastly, the likely large-scale landscape effects are analysed based on documented dynamics for the specie. The results indicate that the conditions exist for the beaver to return to Portugal. The benefits associated with the specie outweigh the costs and the landscape effects are broadly positive. The beaver, besides saving costs in river restoration programs, creates conditions for wildlife to thrive, delivers a wide range of ecosystem services and develops a landscape more resilient to climate change.Os rios e riachos em Portugal estão em más condições ecológicas, programas de restauração de rios são assim essenciais. Vários estudos demonstram que o castor é uma ferramenta importante para melhorar o estado ecológico dos habitats de água doce. Este estudo visa determinar o potencial dos castores para futuros programas de restauro fluvial. O trabalho compara, de uma perspetiva económica e ambiental, uma abordagem de gestão ativa na forma de ações tradicionais de restauro de rios e uma estratégia de gestão passiva na forma de reintrodução de castores. Em primeiro lugar, é apresentado um breve panorama das condições para o castor europeu regressar à paisagem portuguesa. Em segundo lugar, é feita uma estimativa económica com base no potencial de poupança de custos relacionados com o restauro de habitats, despesas de gestão conflitos e os fundos necessários para um programa de reintrodução. Essas estimativas são comparadas com o programa de restauro de rios e ribeiras da APA que decorreu de 2018 a 2020. Em terceiro e último lugar, os prováveis efeitos na paisagem natural são analisados com base em dinâmicas documentadas para a espécie. Os resultados indicam que existem condições para o castor regressar a Portugal. Os benefícios associados à espécie superam os custos e os efeitos na paisagem são amplamente positivos. O castor, além de poupar custos em programas de restauro fluvial, cria condições para a vida selvagem prosperar, fornece uma ampla gama de serviços ecossistémicos e desenvolve uma paisagem mais resistente às alterações climáticas

The Role of Community Values in Wind Energy Development: Exploring the Benefits and Applications of Community Wind for Reducing Local Opposition to Wind Energy Systems

Worldwide, wind energy generation is growing rapidly as a cleaner and less invasive alternative to traditional fossil-fuel energy sources. Yet, in the United States, the advancement of wind energy has been stunted by three factors: (1) the uncertainty of the federal Production Tax Credit; (2) the lack of transmission lines connecting wind projects to electricity grids; and (3) enduring local cultural and aesthetic objections to wind turbines. Frustrated with the imbalanced allocation of costs and benefits imposed by most wind energy projects, some individuals and municipalities have deployed zoning laws, nuisance claims, or environmentalist arguments to discourage wind energy development in their area. “Community wind” is a model of wind energy generation that improves residents’ perception of turbines by using local ownership, services and utility grids to concentrate the economic benefits of wind power in the communities that produce it. This paper sets forth a proposal for applying the community wind model in a suburban context, through the mechanism of the homeowner’s association (HOA). HOAs are uniquely situated to implement community wind to lower their energy costs, provide affordable housing, enhance local schools, and shift Americans’ perception of wind farms in a more positive direction