105,944 research outputs found

    Black body cavity radiometer Patent

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    Black body radiometer having isothermally surrounded cavity for ultraviolet, visible, and infrared radiatio

    Tire/wheel concept

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    A tire and wheel assembly is disclosed in which a low profile pneumatic tire (having sidewalls which deflect inwardly under load) and a wheel (having a rim featuring a narrow central channel and extended rim flanges) form the combination. The extended rim flanges support the tire sidewalls under static and dynamic loading conditions to produce a combination particularly suited to aircraft applications

    The 22-Year Hale Cycle in Cosmic Ray Flux – Evidence for Direct Heliospheric Modulation

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    Abstract The ability to predict times of greater galactic cosmic ray (GCR) fluxes is important for reducing the hazards caused by these particles to satellite communications, aviation, or astronauts. The 11-year solar-cycle variation in cosmic rays is highly correlated with the strength of the heliospheric magnetic field. Differences in GCR flux during alternate solar cycles yield a 22-year cycle, known as the Hale Cycle, which is thought to be due to different particle drift patterns when the northern solar pole has predominantly positive (denoted as qA>0 cycle) or negative (qA0 cycles than for qA0 and more sharply peaked for qA0 solar cycles, when the difference in GCR flux is most apparent. This suggests that particle drifts may not be the sole mechanism responsible for the Hale Cycle in GCR flux at Earth. However, we also demonstrate that these polarity-dependent heliospheric differences are evident during the space-age but are much less clear in earlier data: using geomagnetic reconstructions, we show that for the period of 1905 – 1965, alternate polarities do not give as significant a difference during the declining phase of the solar cycle. Thus we suggest that the 22-year cycle in cosmic-ray flux is at least partly the result of direct modulation by the heliospheric magnetic field and that this effect may be primarily limited to the grand solar maximum of the space-age

    The JPL standard total-radiation absolute radiometer

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    Standard total-radiation absolute radiometer with improved accuracy for calibrating radiometers for simulated solar radiation measuremen

    Radiometer for accurate (+ or - 1%) measurement of solar irradiance equal to 10,000 solar constants

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    The 10,000 solar constant radiometer was developed for the accurate (+ or - 1%) measurement of the irradiance produced in the image formed by a parabolic reflector or by a multiple mirror solar installation. This radiometer is water cooled, weighs about 1 kg, and is 5 cm (2 in.) in diameter by 10 cm (4 in.) long. A sting is provided for mounting the radiometer in the solar installation capable of measuring irradiances as high as 20,000 solar constants, the instrument is self calibrating. Its accuracy depends on the accurate determination of the cavity aperture, and absorptivity of the cavity, and accurate electrical measurements. The spectral response is flat over the entire spectrum from far UV to far IR. The radiometer responds to a measurement within 99.7% of the final value within 8 s. During a measurement of the 10,000 solar constant irradiance, the temperature rise of the water is about 20 C. The radiometer has perfect cosine response up to 60 deg off the radiometer axis

    Optical tomography using the SCIRun problem solving environment: Preliminary results for three-dimensional geometries and parallel processing

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    We present a 3D implementation of the UCL imaging package for absorption and scatter reconstruction from time-resolved data (TOAST), embedded in the SCIRun interactive simulation and visualization package developed at the University of Utah. SCIRun is a scientific programming environment that allows the interactive construction, debugging, and steering of large-scale scientific computations. While the capabilities of SCIRun's interactive approach are not yet fully exploited in the current TOAST implementation, an immediate benefit of the combined TOAST/SCIRun package is the availability of optimized parallel finite element forward solvers, and the use of SCIRun's existing 3D visualisation tools. A reconstruction of a segmented 3D head model is used as an example for demonstrating the capability of TOAST/SCIRun of simulating anatomically shaped meshes

    Improved cavity-type absolute total-radiation radiometer

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    Conical cavity-type absolute radiometer measures the intensity of radiant energy to an accuracy of one to two percent in a vacuum of ten to the minus fifth torr or lower. There is a uniform response over the ultraviolet, visible, and infrared range, and it requires no calibration or comparison with a radiation standard

    Micro-mechanical finite element analysis of Z-pins under mixed-mode loading

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    © 2015 Elsevier Ltd. All rights reserved.This paper presents a three-dimensional micro-mechanical finite element (FE) modelling strategy for predicting the mixed-mode response of single Z-pins inserted in a composite laminate. The modelling approach is based upon a versatile ply-level mesh, which takes into account the significant micro-mechanical features of Z-pinned laminates. The effect of post-cure cool down is also considered in the approach. The Z-pin/laminate interface is modelled by cohesive elements and frictional contact. The progressive failure of the Z-pin is simulated considering shear-driven internal splitting, accounted for using cohesive elements, and tensile fibre failure, modelled using the Weibulls criterion. The simulation strategy is calibrated and validated via experimental tests performed on single carbon/BMI Z-pins inserted in quasi-isotropic laminate. The effects of the bonding and friction at the Z-pin/laminate interface and the internal Z-pin splitting are discussed. The primary aim is to develop a robust numerical tool and guidelines for designing Z-pins with optimal bridging behaviour

    A Rare Case of Isolated torsion of Haematosalphinx Presenting as Acute Abdomen During Pregnancy

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    Isolated fallopian tubal torsion is a rare non obstetric cause for pain abdomen during pregnancy.We report a case of a 34 year old second gravida who presented with history of amennorrhoe of 7 months, colicky pain in the left iliac fossa , with 2 episodes of vomiting. A Trans vaginal scan revealed a left ovarian cyst. An emergency laparotomy was performed for suspected torsion or haemorrhage into an ovarian cyst. Surprisingly ovaries were normal and a congested and necrotic left tubal torsion with a tubal collection (haematosalphinx) was identified and a salpingectomy was then performed. The differential diagnosis is discussed and the literature is reviewed as it is a very rare clinical entity

    3-manifold groups are virtually residually p

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    Given a prime pp, a group is called residually pp if the intersection of its pp-power index normal subgroups is trivial. A group is called virtually residually pp if it has a finite index subgroup which is residually pp. It is well-known that finitely generated linear groups over fields of characteristic zero are virtually residually pp for all but finitely many pp. In particular, fundamental groups of hyperbolic 3-manifolds are virtually residually pp. It is also well-known that fundamental groups of 3-manifolds are residually finite. In this paper we prove a common generalization of these results: every 3-manifold group is virtually residually pp for all but finitely many pp. This gives evidence for the conjecture (Thurston) that fundamental groups of 3-manifolds are linear groups
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