627 research outputs found

    Detection Improvised Explosive Device (IED) Emplacement Using Infrared Image

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    This paper presents a method to detect an improvised explosive device (IED) by using infrared thermography (IRT) technology. The detection of IED will be done automatically and accurately even the IED detection expert is not present. Combining the advantage of IRT and image processing technique, the proposed method is very efficient and responsive to detect the existence of hidden IED. The captured images are filtered and segmented to extract the heat pattern before the decision is made. Based on the experimental result, the proposed system produced about 92 % of detection accuracy

    Solid deuterium surface degradation at ultracold neutron sources

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    Solid deuterium (sD_2) is used as an efficient converter to produce ultracold neutrons (UCN). It is known that the sD_2 must be sufficiently cold, of high purity and mostly in its ortho-state in order to guarantee long lifetimes of UCN in the solid from which they are extracted into vacuum. Also the UCN transparency of the bulk sD_2 material must be high because crystal inhomogeneities limit the mean free path for elastic scattering and reduce the extraction efficiency. Observations at the UCN sources at Paul Scherrer Institute and at Los Alamos National Laboratory consistently show a decrease of the UCN yield with time of operation after initial preparation or later treatment (`conditioning') of the sD_2. We show that, in addition to the quality of the bulk sD_2, the quality of its surface is essential. Our observations and simulations support the view that the surface is deteriorating due to a build-up of D_2 frost-layers under pulsed operation which leads to strong albedo reflections of UCN and subsequent loss. We report results of UCN yield measurements, temperature and pressure behavior of deuterium during source operation and conditioning, and UCN transport simulations. This, together with optical observations of sD_2 frost formation on initially transparent sD_2 in offline studies with pulsed heat input at the North Carolina State University UCN source results in a consistent description of the UCN yield decrease.Comment: 15 pages, 22 figures, accepted by EPJ-

    Inequalities For Numerical Radius And The Spectral Norm Of Hilbert Space Operators

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    Let (H,< .,. >) be a complex Hilbert space and B(H) denote the C-algebra of all bounded linear operators on H. In this paper we establishinequalities for numerical radius and the spectral norm of Hilbert spaceoperators , from the previous inequalitiesMathematics Subject Classi?cation: 47A12,47A63; 47A99.Keywords: Numerical Radius, Complex Hilbert Space, Operator Norm,Boundedlinear operators, Inequalities for norms and numerical radius

    Soluble tumor necrosis factor receptor 1 and 2 predict outcomes in advanced chronic kidney disease : a prospective cohort study

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    Background : Soluble tumor necrosis factor receptors 1 (sTNFR1) and 2 (sTNFR2) have been associated to progression of renal failure, end stage renal disease and mortality in early stages of chronic kidney disease (CKD), mostly in the context of diabetic nephropathy. The predictive value of these markers in advanced stages of CKD irrespective of the specific causes of kidney disease has not yet been defined. In this study, the relationship between sTNFR1 and sTNFR2 and the risk for adverse cardiovascular events (CVE) and all-cause mortality was investigated in a population with CKD stage 4-5, not yet on dialysis, to minimize the confounding by renal function. Patients and methods : In 131 patients, CKD stage 4-5, sTNFR1, sTNFR2 were analysed for their association to a composite endpoint of all-cause mortality or first non-fatal CVE by univariate and multivariate Cox proportional hazards models. In the multivariate models, age, gender, CRP, eGFR and significant comorbidities were included as covariates. Results : During a median follow-up of 33 months, 40 events (30.5%) occurred of which 29 deaths (22.1%) and 11 (8.4%) first non-fatal CVE. In univariate analysis, the hazard ratios (HR) of sTNFR1 and sTNFR2 for negative outcome were 1.49 (95% confidence interval (CI): 1.28-1.75) and 1.13 (95% CI: 1.06-1.20) respectively. After adjustment for clinical covariables (age, CRP, diabetes and a history of cardiovascular disease) both sTNFRs remained independently associated to outcomes (HR: sTNFR1: 1.51, 95% CI: 1.30-1.77; sTNFR2: 1.13, 95% CI: 1.06-1.20). A subanalysis of the non-diabetic patients in the study population confirmed these findings, especially for sTNFR1. Conclusion : sTNFR1 and sTNFR2 are independently associated to all-cause mortality or an increased risk for cardiovascular events in advanced CKD irrespective of the cause of kidney disease

    First Measurement of the Neutron β\beta-Asymmetry with Ultracold Neutrons

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    We report the first measurement of angular correlation parameters in neutron β\beta-decay using polarized ultracold neutrons (UCN). We utilize UCN with energies below about 200 neV, which we guide and store for 30\sim 30 s in a Cu decay volume. The μnB\vec{\mu}_n \cdot \vec{B} potential of a static 7 T field external to the decay volume provides a 420 neV potential energy barrier to the spin state parallel to the field, polarizing the UCN before they pass through an adiabatic fast passage (AFP) spin-flipper and enter a decay volume, situated within a 1 T, 2×2π2 \times 2\pi superconducting solenoidal spectrometer. We determine a value for the β\beta-asymmetry parameter A0A_0, proportional to the angular correlation between the neutron polarization and the electron momentum, of A0=0.1138±0.0051A_0 = -0.1138 \pm 0.0051.Comment: 4 pages, 2 figures, 1 table, submitted to Phys. Rev. Let

    Special Cases for Numerical Radius and Spectral Radius Inequalities

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    In  this paper, the aim of this study  is to find special cases  of  some inequalities for numerical radius and spectral radius of a bounded linear operator on a Hilbert space, Finally, some new results about this subject are obtained. Keywords: Spectral norm, Numerical radius, Spectral radius
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