389 research outputs found

    X-ray photoelectron spectroscopy study of nickel and nickel-base alloy surface alterations in simulated hot corrosion conditions with emphasis on eventual application to turbine blade corrosion

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    Research on the high temperature oxidation and Na2SO4 induced hot corrosion of some nickel base superalloys was accomplished by using ESCA to determine the surface composition of the oxidized or corroded samples. Oxidation was carried out at 900 or 1000 C in slowly flowing O2 for samples of B-1900, NASA-TRW VIA, 713C, and IN-738. Oxidation times ranged from 0.5 to 100 hr. Hot corrosion of B-1900 was induced applying a coating of Na2SO4 to peroxidized samples, the heating to 900 C in slowly flowing O2. For oxidized samples, the predominant type of scale formed by each superalloy was determined, and a marked surface enrichment of Ti was found in each case. For corroded samples, the transfer of significant amounts of material from the oxide layer to the surface of the salt layer was observed to occur long before the onset of accelerating weight-gain. Changes in surface composition were observed to coincide with the beginning of accelerating corrosion, the most striking of which was a tenfold decrease in the sulfur to sodium ration and an increase in the Cr(VI) ratio

    Urinary bladder melanosis with complete resolution case report

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    Background Melanosis of the bladder is a rare condition characterized by multifocal, diffuse melanin pigmentation of the urothelial mucosa or lamina propria without any proliferation of melanocytes. Less than 25 cases have been reported so far of which only four patients had concurrent urothelial carcinoma. Case presentation We are reporting a case of melanosis of the bladder in a 58-year-old female associated with pTaG1 transitional urothelial cell carcinoma (TCC) of the bladder who presented with symptoms of recurrent urinary tract infection (UTI). Cystoscopy and biopsy results confirmed benign melanosis. Conclusion Our case is unique because bladder melanosis associated low grade TCC with complete resolution of both conditions within one year

    USE OF AN INNOVATIVE METHOD FOR STRUCTURAL ANALYSIS OF THE DISTRIBUTION DEVICE USED IN PNEUMATIC MACHINES FOR WEEDING PLANT SOWING

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    The topic addressed is a computer-aided design (CAD) method combined with computer-aided engineering (CAE) used in the analysis of choosing the optimal constructive variant of the distribution device used in pneumatic machines for weeding plant sowing. The CAD configurations, realized by the 3D parametric modeling using the SolidWorks program, were subjected to structural analysis (von Mises equivalent stress distribution, relative displacement field distribution and safety factor). Based on the resulting data, the mass/resistance coefficient for the 3 analyzed configurations were determined. The comparison of these indicators led to the choice of the optimal constructive variant, namely the most efficient one

    Nuclear magnetic resonance spectroscopy: An experimentally accessible paradigm for quantum computing

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    We present experimental results which demonstrate that nuclear magnetic resonance spectroscopy is capable of efficiently emulating many of the capabilities of quantum computers, including unitary evolution and coherent superpositions, but without attendant wave-function collapse. Specifically, we have: (1) Implemented the quantum XOR gate in two different ways, one using Pound-Overhauser double resonance, and the other using a spin-coherence double resonance pulse sequence; (2) Demonstrated that the square root of the Pound-Overhauser XOR corresponds to a conditional rotation, thus obtaining a universal set of gates; (3) Devised a spin-coherence implementation of the Toffoli gate, and confirmed that it transforms the equilibrium state of a four-spin system as expected; (4) Used standard gradient-pulse techniques in NMR to equalize all but one of the populations in a two-spin system, so obtaining the pseudo-pure state that corresponds to |00>; (5) Validated that one can identify which basic pseudo-pure state is present by transforming it into one-spin superpositions, whose associated spectra jointly characterize the state; (6) Applied the spin-coherence XOR gate to a one-spin superposition to create an entangled state, and confirmed its existence by detecting the associated double-quantum coherence via gradient-echo methods.Comment: LaTeX + epsfig + amsmath packages, 27 pages, 12 figures, to appear in Physica D; revision updates list of authors and reference

    Unambiguous 1-Uniform Morphisms

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    A morphism h is unambiguous with respect to a word w if there is no other morphism g that maps w to the same image as h. In the present paper we study the question of whether, for any given word, there exists an unambiguous 1-uniform morphism, i.e., a morphism that maps every letter in the word to an image of length 1.Comment: In Proceedings WORDS 2011, arXiv:1108.341

    CAD-CAE METHOD FOR STRUCTURAL ANALYSIS OF THE WELDED FRAME WITHIN THE COMPONENT OF A SEED DRILL USED FORDIRECTLY SOWING STRAW CEREALS

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    This paper presents a Computer Assisted Design (CAD) method combined with computer-aided engineering (CAE) used in the analysis of choosing the constructive variant of the welded frame from within the component of a seed drill used fordirectly sowing straw cereals, so that the ratio between the consumption of material for the construction structure per unit of safety coefficient to be minimal and the carrying capacity to be maximal. For this purpose 3D modeling with SolidWorks software has effectively managed three dimensional configurations of the welded frame using Design Table. The three configurations were subjected to structural analysis (the von Mises equivalent of the tension field distribution, the relative displacement of field distribution and the safety coefficient). Based on the resulting data, the mass / resistance ratios for the three configurations analyzed were determined. The comparison of these indicators led to the choice of the optimal constructive variant in the most efficient way. The presented method contributes to reducing the design validation time by eliminating physical performance and testing

    Comment on "Long-range electrostatic interactions between like-charged colloids: Steric and confinement effects"

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    In a recent study [Phys. Rev. E 60, 6530 (1999)], Trizac and Raimbault showed that the effective pair interaction between like charged colloids immersed in a cylindrically confined electrolyte remains repulsive even when the size of the micro-ions or the finite longitudinal extension of the confining cylinder are taken into account. Contrary to their claim, we argue that the case of finite longitudinal confinement doesn't always generate repulsive interactions and to illustrate this point we also provide a simple example.Comment: 3 pages, 1 figure. Accepted for publication in Phys. Rev. E 200

    Formal Analysis of a Fault-Tolerant Routing Algorithm for a Network-on-Chip

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    International audienceA fault-tolerant routing algorithm in Network-on-Chip architectures provides adaptivity for on-chip communications. Adding fault-tolerance adaptivity to a routing algorithm increases its design complexity and makes it prone to deadlock and other problems if improperly implemented. Formal verification techniques are needed to check the correctness of the design. This paper performs formal analysis on an extension of the link-fault tolerant Network-on-Chip architecture introduced by Wu et al. that supports multiflit wormhole routing. This paper describes several lessons learned during the process of constructing a formal model of this routing architecture. Finally, this paper presents how the deadlock freedom and tolerance to a single-link fault is verified for a two-by-two mesh version of this routing architecture
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