13,843 research outputs found

    X-ray film holder permits single continuous picture of tubing joint

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    X ray technique produces a clear continuous picture of a welded brazed tubing joint on a single film with one exposure. A stationary X ray source located in the plane of the joint to be inspected, a means of rotating the tube, and a unique internal film holder and positioning fixture are used

    Remote sensing of atmospheric winds using a coherent, CW lidar and speckle-turbulence interaction

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    Speckle turbulence interaction has the potential for allowing single ended remote sensing of the path averaged vector crosswind in a plane perpendicular to the line of sight to a target. If a laser transmitter is used to illuminate a target, the resultant speckle field generated by the target is randomly perturbed by the atmospheric turbulence as it propagates back to the location of the transmitter-receiver. When a cross wind is present, this scintillation pattern will move with time across the receiver. A continuous wave (cw) laser transmitter of modest power level in conjunction with optical heterodyne detection was used to exploit the speckel turbulence interaction and measure the crosswind. The use of a cw transmitter at 10.6 microns and optical heterodyne detection has many advantages over direct detection and a double pulsed source in the visible or near infrared. These advantages include the availability of compact, reliable and inexpensive transmitters, better penetration of smoke, dust and fog; stable output power; low beam pointing jitter; and considerably reduced complexity in the receiver electronics

    Solar silicon via the Dow Corning process

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    Carbon, as a reductant for quartz, must be made available so as to have suitable reactivity in conjunction with high purity, especially with respect to boron and phosphorus. A detailed experimental plan was developed to do this. Different sources of carbon were selected to be subjected to various purification methods and reactivity-enhancement processes. A developmental scale arc furnace was installed to perform quartz-carbon reactivity testing

    Fusiform Rust Trends in East Texas

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    Four surveys of pine plantations in East Texas between 1969 and 1984 indicate that fusiform rust (Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. fusiforme) infection rates are increasing on slash pine (Pinus elliottii Engelm. var. elliottii) and either decreasing or about constant on loblolly pine (Pinus taeda L.). Currently, stem infections occur on about 1 in 2 slash pines and 1 in 14 loblolly pines. South. J. Appl. For. 10:215-216, Nov. 1986

    Bicriteria Network Design Problems

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    We study a general class of bicriteria network design problems. A generic problem in this class is as follows: Given an undirected graph and two minimization objectives (under different cost functions), with a budget specified on the first, find a <subgraph \from a given subgraph-class that minimizes the second objective subject to the budget on the first. We consider three different criteria - the total edge cost, the diameter and the maximum degree of the network. Here, we present the first polynomial-time approximation algorithms for a large class of bicriteria network design problems for the above mentioned criteria. The following general types of results are presented. First, we develop a framework for bicriteria problems and their approximations. Second, when the two criteria are the same %(note that the cost functions continue to be different) we present a ``black box'' parametric search technique. This black box takes in as input an (approximation) algorithm for the unicriterion situation and generates an approximation algorithm for the bicriteria case with only a constant factor loss in the performance guarantee. Third, when the two criteria are the diameter and the total edge costs we use a cluster-based approach to devise a approximation algorithms --- the solutions output violate both the criteria by a logarithmic factor. Finally, for the class of treewidth-bounded graphs, we provide pseudopolynomial-time algorithms for a number of bicriteria problems using dynamic programming. We show how these pseudopolynomial-time algorithms can be converted to fully polynomial-time approximation schemes using a scaling technique.Comment: 24 pages 1 figur

    Progression and assessment in foreign languages at Key Stage 2

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    The teaching of primary languages has been increasing steadily, in response to the future entitlement for all Key Stage 2 (KS2) pupils aged 7-11 to learn a foreign language by 2010. However, there remain concerns about progression both within KS2 and through to secondary school and about how learners' progress is assessed. This paper presents findings on the issues of progression and assessment taken from case studies which formed part of a project funded by the then Department for Education and Skills (DfES), now the Department for Children, Schools and Families (DCSF). This project set out to evaluate 19 local authority (LA) Pathfinders in England that were piloting the introduction of foreign language learning at KS2 between 2003 and 2005. Findings revealed that there was inconsistency between schools, even within each LA Pathfinder, in the use of schemes of work and that assessment was generally underdeveloped in the majority of the Pathfinders. In order to set these findings in context, this paper examines the issues of progression and assessment in foreign language learning in England. Finally, it investigates the challenges English primary schools face in terms of progression and assessment in the light of the new entitlement and discusses implications for the future. Managing progression, both within KS2 and through to secondary school at KS3 (ages 11-14), is one of the key factors in determining the overall success of starting languages in primary school

    Construction 4.0:A Systematic Review of Its Application in Developing Countries

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    This study conducts a literature review to analyse the incorporation of Industry 4.0 in the construction sector, known as Construction 4.0, in developing countries. This study utilises an effective technique, encompassing academic databases, journals, and conference proceedings, to carefully examine relevant studies published with respect to developing countries. The primary areas of emphasis involve the definition of Construction 4.0. The technologies of execution include six cutting-edge technologies such as Building Information Modelling (BIM), Internet of Things (IoT), robotics, 3D printing, UAVs, and artificial intelligence in construction procedures. This analysis also explores the awareness and understanding of Industry 4.0 in the construction sector (Construction 4.0) in developing countries before identifying where it is being applied therein. Furthermore, obstacles that impede the mainstream adoption in developing countries are identified, including but not limited to such things as insufficient technological infrastructure, skill deficiencies, and budgetary limitations. This review consolidates various studies to provide a thorough comprehension of the present condition of Construction 4.0 in developing nations. As such, this paper aims to provide a guide for future research, policy making, and industry practices in order to promote sustainable and technologically advanced construction methods in these settings

    Probability of local bifurcation type from a fixed point: A random matrix perspective

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    Results regarding probable bifurcations from fixed points are presented in the context of general dynamical systems (real, random matrices), time-delay dynamical systems (companion matrices), and a set of mappings known for their properties as universal approximators (neural networks). The eigenvalue spectra is considered both numerically and analytically using previous work of Edelman et. al. Based upon the numerical evidence, various conjectures are presented. The conclusion is that in many circumstances, most bifurcations from fixed points of large dynamical systems will be due to complex eigenvalues. Nevertheless, surprising situations are presented for which the aforementioned conclusion is not general, e.g. real random matrices with Gaussian elements with a large positive mean and finite variance.Comment: 21 pages, 19 figure

    Structure of 10N in 9C+p resonance scattering

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    The structure of exotic nucleus 10N was studied using 9C+p resonance scattering. Two L=0 resonances were found to be the lowest states in 10N. The ground state of 10N is unbound with respect to proton decay by 2.2(2) or 1.9(2) MeV depending on the 2- or 1- spin-parity assignment, and the first excited state is unbound by 2.8(2) MeV.Comment: 6 pages, 4 figures, 1 table, submitted to Phys. Lett.
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