1,228 research outputs found

    Appropriate technology for sustainable food security:

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    CONTENTS: Brief 1. Overview / Per Pinstrup-Andersen Brief 2. Farmer-Based Agro-Ecological Technology / Jules Pretty Brief 3. Conventional Research-Based Technology / Prabhu Pingali Brief 4. Modern Biotechnology / Calestous Juma Brief 5. Modern Technology for African Agriculture / Jennifer Thomson Brief 6. Information and Communcations Technologies / Nuimuddin Chowdhury Brief 7. GIS, GPS, and Remote Sensing / Uwe Deichmann and Stanley Wood Brief 8. Alternative Energy Sources / R. K. Pachauri and Pooja Mehrotra Brief 9. Food Irradiation / Morton SatinTechnology., Technological innovations., Food security., Sustainability.,

    A Decomposed Fourier-Motzkin Elimination Framework to Derive Vessel Capacity Models

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    Accurate Vessel Capacity Models (VCMs) expressing thetrade-off between different container types that can be stowed on containervessels are required in core liner shipping functions such as uptake-,capacity-, and network management. Today, simple models based on volume,weight, and refrigerated container capacity are used for these tasks,which causes overestimations that hamper decision making. Though previouswork on stowage planning optimization in principle provide finegrainedlinear Vessel Stowage Models (VSMs), these are too complexto be used in the mentioned functions. As an alternative, this papercontributes a novel framework based on Fourier-Motzkin Eliminationthat automatically derives VCMs from VSMs by projecting unneededvariables. Our results show that the projected VCMs are reduced byan order of magnitude and can be solved 20–34 times faster than theircorresponding VSMs with only a negligible loss in accuracy. Our frameworkis applicable to LP models in general, but are particularly effectiveon block-angular structured problems such as VSMs. We show similarresults for a multi-commodity flow problem

    A second order cone formulation of continuous CTA model

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    The final publication is available at link.springer.comIn this paper we consider a minimum distance Controlled Tabular Adjustment (CTA) model for statistical disclosure limitation (control) of tabular data. The goal of the CTA model is to find the closest safe table to some original tabular data set that contains sensitive information. The measure of closeness is usually measured using l1 or l2 norm; with each measure having its advantages and disadvantages. Recently, in [4] a regularization of the l1 -CTA using Pseudo-Huber func- tion was introduced in an attempt to combine positive characteristics of both l1 -CTA and l2 -CTA. All three models can be solved using appro- priate versions of Interior-Point Methods (IPM). It is known that IPM in general works better on well structured problems such as conic op- timization problems, thus, reformulation of these CTA models as conic optimization problem may be advantageous. We present reformulation of Pseudo-Huber-CTA, and l1 -CTA as Second-Order Cone (SOC) op- timization problems and test the validity of the approach on the small example of two-dimensional tabular data set.Peer ReviewedPostprint (author's final draft

    Progress toward developing the TMT adaptive optical systems and their components

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    Atmospheric turbulence compensation via adaptive optics (AO) will be essential for achieving most objectives of the TMT science case. The performance requirements for the initial implementation of the observatory's facility AO system include diffraction-limited performance in the near IR with 50 per cent sky coverage at the galactic pole. This capability will be achieved via an order 60x60 multi-conjugate AO system (NFIRAOS) with two deformable mirrors optically conjugate to ranges of 0 and 12 km, six high-order wavefront sensors observing laser guide stars in the mesospheric sodium layer, and up to three low-order, IR, natural guide star wavefront sensors located within each client instrument. The associated laser guide star facility (LGSF) will consist of 3 50W class, solid state, sum frequency lasers, conventional beam transport optics, and a launch telescope located behind the TMT secondary mirror. In this paper, we report on the progress made in designing, modeling, and validating these systems and their components over the last two years. This includes work on the overall layout and detailed opto-mechanical designs of NFIRAOS and the LGSF; reliable wavefront sensing methods for use with elongated and time-varying sodium laser guide stars; developing and validating a robust tip/tilt control architecture and its components; computationally efficient algorithms for very high order wavefront control; detailed AO system modeling and performance optimization incorporating all of these effects; and a range of supporting lab/field tests and component prototyping activities at TMT partners. Further details may be found in the additional papers on each of the above topics

    A Machine Verified Distributed Sorting Algorithm

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    We present a verification of a distributed sorting algorithm in ALF,an implementation of Martin L¨of's type theory. The implementationis expressed as a program in a prioritized version of CBS, (the Calculus of Broadcasting Systems) which we have implemented in ALF. The specification is expressed in terms of an ALF type which represents the set of all sorted lists and an HML (Hennesey-Milner Logic) formula which expresses that the sorting program will input any number of data until it hears a value triggering the program to begin outputting the data in a sorted fashion. We gain expressive power from the type theory by inheriting the language of data, state expressions, and propositions

    Where is the Target? An Examination of the Conceptions of Student Engagement within a School Community

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    In 2017, the Kansas State Department of Education (KSDE) launched an ambitious school redesign project. High Plains High School (pseudonym) was among the schools selected for redesign, and as part of their plan, High Plains High School (HPHS) faculty and staff administered a survey to students. Survey results indicated approximately 38% of students felt “disengaged” at school. HPHS administrators found these results worthy of study, in an attempt to understand how students, faculty, and families were conceptualizing school engagement. Results indicate that each constituency tended toward differing concepts of what it means to be engaged in the classroom. Implications include the need for teacher educators to more deeply address preservice students’ understanding of engagement, as well as a shift to a conceptual understanding of student engagement that is more agentic. Results could catalyze changes in educator preparation programs to improve candidates’ understanding of engagement and its role in student success
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