3,301 research outputs found

    Choice of suitable Identity and Access Management standards for mobile computing and communication

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    © 2017 IEEE. Enterprises have recognised the importance of personal mobile devices for business and official use. Employees and consumers have been freely accessing resources and services from their principal organisation and partners' businesses on their mobile devices, to improve the efficiency and productivity of their businesses. This mobile computing-based business model has one major challenge, that of ascertaining and linking users' identities and access rights across business partners. The parent organisation owns all the confidential information about users but the collaborative organisation has to verify users' identities and access rights to allow access to their services and resources. This challenge involves resolving how to communicate users' identities to collaborative organisations without sending their confidential information. Several generic Identity and Access Management (IAM) standards have been proposed, and three have become established standards: Security Assertion Markup Language (SAML), Open Authentication (OAuth), and OpenID Connect (OIDC). Mobile computing and communication have some specific requirements and limitations; therefore, this paper evaluates these IAM standards to ascertain suitable IAM to protect mobile computing and communication. This evaluation is based on the three types of analyses: Comparative analysis, suitability analysis and security vulnerability analysis of SAML, OAuth and OIDC

    Near-surface remote sensing of spatial and temporal variation in canopy phenology

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    There is a need to document how plant phenology is responding to global change factors, particularly warming trends. “Near-surface” remote sensing, using radiometric instruments or imaging sensors, has great potential to improve phenological monitoring because automated observations can be made at high temporal frequency. Here we build on previous work and show how inexpensive, networked digital cameras (“webcams”) can be used to document spatial and temporal variation in the spring and autumn phenology of forest canopies. We use two years of imagery from a deciduous, northern hardwood site, and one year of imagery from a coniferous, boreal transition site. A quantitative signal is obtained by splitting images into separate red, green, and blue color channels and calculating the relative brightness of each channel for “regions of interest” within each image. We put the observed phenological signal in context by relating it to seasonal patterns of gross primary productivity, inferred from eddy covariance measurements of surface–atmosphere CO2 exchange. We show that spring increases, and autumn decreases, in canopy greenness can be detected in both deciduous and coniferous stands. In deciduous stands, an autumn red peak is also observed. The timing and rate of spring development and autumn senescence varies across the canopy, with greater variability in autumn than spring. Interannual variation in phenology can be detected both visually and quantitatively; delayed spring onset in 2007 compared to 2006 is related to a prolonged cold spell from day 85 to day 110. This work lays the foundation for regional- to continental-scale camera-based monitoring of phenology at network observatory sites, e.g., National Ecological Observatory Network (NEON) or AmeriFlux

    Photodetector Development for the Wheel Abrasion Experiment on the Sojourner Microrover of the Mars Pathfinder Mission

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    On-board the Mars Pathfinder spacecraft, launched in December of 1996, is a small roving vehicle named Sojourner. On Sojourner is an experiment to determine the abrasive characteristics of the Martian surface, called the Wheel Abrasion Experiment (WAE). The experiment works as follows: one of the wheels of the rover has a strip of black anodized aluminum bonded to the tread. The aluminum strip has thin coatings of aluminum, nickel and platinum deposited in patches. There are five (5) patches or samples of each metal, and the patches range in thickness from 200 A to 1000 A. The different metals were chosen for their differing hardness and their environmental stability. As the wheel is spun in the Martian soil, the thin patches of metal are abraded away, exposing the black anodization. The abrasion is monitored by measuring the amount of light reflected off of the samples. A photodetector was developed for this purpose, and that is the subject of this paper

    Alpha voltaic batteries and methods thereof

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    An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material
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