1,231 research outputs found

    Load-shedding probabilities with hybrid renewable power generation and energy storage

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    The integration of renewable energy resources, such as solar and wind power, into the electric grid presents challengs partly due to the intermittency in the power output. These difficulties can be alleviated by effectively utilizing energy storage. We consider, as a case study, the integration of renewable resources into the electric power generation portfolio of an island off the coast of Southern California, Santa Catalina Island, and investigate the feasibility of replacing diesel generation entirely with solar photovoltaics (PV) and wind turbines, supplemented with energy storage. We use a simple storage model alongside a combination of renewables and varying load-shedding characterizations to determine the appropriate area of PV cells, number of wind turbines, and energy storage capacity needed to stay below a certain threshold probability for load-shedding over a pre-specified period of time and long-term expected fraction of time at load-shedding

    The use of design activity for research into Computer Supported Co-operative Working (CSCW)

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    This paper describes current research at Loughborough University in the field of Computer Supported Co-operative Working (CSCW). The project, which is funded by the Information Engineering Directorate (IED) within the Science and Engineering Research Council (SERC), is titled 'Establishing the Communicational Requirements of Information Technology (IT) Systems that Support Humans Co-operating Remotely'. The research group have adopted a less cumbersome acronym for the project - ROCOCO which is derived from REmote COoperation and COmmunication. Design activity has been proposed as offering a suitable context for a study of co-operation and at the time of writing the first phase of the experiments - involving face to face or proximal co-operation - has been undertaken and the analysis begun. The ROCOCO project is about to embark on phase two involving remote co-operation. This paper presents, in some detail, the construction and operation of a pilot study that allowed project members to assess and adjust the experimental design prior to the start of Phase One. A selection of initial findings illustrate the nature of the investigation to be undertaken. The paper also seeks to highlight the importance of CSCW research for the design community. The substance of the paper is concerned with a presentation of issues involved in an analysis of co-operation, involving as it does, verbal and non-verbal communication

    The Gain Reduction Method for manual tracking of radio-tagged fish in streams

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    Background: Manual tracking has been used since the 1970s as an effective radio telemetry approach for evaluating habitat use of fish in fluvial systems. Radio tags are often located by continually reducing the gain when approaching the tag along a watercourse to estimate its location, termed here as the 'Gain Reduction Method'. However, to our knowledge the accuracy of this method has not been empirically evaluated and reported in the literature. Here, the longitudinal and lateral positional errors of radio tags are assessed when applying the Gain Reduction Method in a small stream environment. Longitudinal and lateral positional errors (i.e. the difference between the e

    Measures of Parent-Infant Interaction

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    Increasingly, programs for handicapped infants and toddlers are including in their intervention activities objectives related to the quality of parent-child interaction. As a consequence, it has become necessary for programs to assess the impact of these intervention efforts on parent behaviors. This article considers tools available for assessing parent-child interaction for program planning and evaluation. Lastly, recommendations are offered to guide the selection of a measure of parent-child interactions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69100/2/10.1177_027112148600600204.pd

    Food-Web Structure of Seagrass Communities across Different Spatial Scales and Human Impacts

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    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis is critical for determining results

    Photonic Doppler velocimetry probe used to measure grain boundaries of dynamic shocked materials

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    Author Institution: Mission Support and Test Services, LLC; Los Alamos National LaboratorySlides presented at the 2018 Photonic Doppler Velocimetry (PDV) Users Workshop, Drury Plaza Hotel, Santa Fe, New Mexico, May 16-18, 2018

    Continuous and transparent multimodal authentication: reviewing the state of the art

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    Individuals, businesses and governments undertake an ever-growing range of activities online and via various Internet-enabled digital devices. Unfortunately, these activities, services, information and devices are the targets of cybercrimes. Verifying the user legitimacy to use/access a digital device or service has become of the utmost importance. Authentication is the frontline countermeasure of ensuring only the authorized user is granted access; however, it has historically suffered from a range of issues related to the security and usability of the approaches. They are also still mostly functioning at the point of entry and those performing sort of re-authentication executing it in an intrusive manner. Thus, it is apparent that a more innovative, convenient and secure user authentication solution is vital. This paper reviews the authentication methods along with the current use of authentication technologies, aiming at developing a current state-of-the-art and identifying the open problems to be tackled and available solutions to be adopted. It also investigates whether these authentication technologies have the capability to fill the gap between high security and user satisfaction. This is followed by a literature review of the existing research on continuous and transparent multimodal authentication. It concludes that providing users with adequate protection and convenience requires innovative robust authentication mechanisms to be utilized in a universal level. Ultimately, a potential federated biometric authentication solution is presented; however it needs to be developed and extensively evaluated, thus operating in a transparent, continuous and user-friendly manner
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