51,559 research outputs found

    Why Reinvent the Wheel? The Efficacy of the Systematic Problem Solving Method 'TRIZ' and it Value for Innovation in Engineering and Implications for Engineering Management

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    The engineering industry needs to be more innovative. A case study of a recent breakthrough innovative development by Michelin is discussed. The influence of prior training with systematic problem solving method TRIZ, on the innovation team, is assessed using a questionnaire. The questionnaire is based on a company innovation audit model proposed by Mann and influenced by the creativity model of Baille. Results are discussed which show significant innovation development when using TRIZ. The efficacy of training key workers in systematic problem solving and creative methods is discussed and the implications for managers in innovation promotion and workplace environment change are highlighted

    Preface and Thank You, Arthur!

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    Very Massive Stars and the Eddington Limit

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    We use contemporary evolutionary models for Very Massive Stars (VMS) to assess whether the Eddington limit constrains the upper stellar mass limit. We also consider the interplay between mass and age for the wind properties and spectral morphology of VMS, with reference to the recently modified classification scheme for O2-3.5If*/WN stars. Finally, the death of VMS in the local universe is considered in the context of pair instability supernovae.Comment: 6 pages, 4 figures, from "Four Decades of Massive Star Research" (Quebec, Jul 2011), ASP Conf Ser, in press (L. Drissen, C. Robert, N. St-Louis, A.F.J. Moffat, eds.

    AN EMPIRICAL TEST OF THE INTERVAL APPROACH FOR ESTIMATING RISK PREFERENCES

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    Previous attempts to measure agricultural decision makers' risk preferences have obtained values of the Arrow-Pratt coefficient in the range of approximately -.0002 to .0012. The recently developed interval approach for elicitation of risk preferences was used to estimate risk attitudes for Minnesota swine producers. Constant and decreasing absolute risk aversion were predominant among the sample. Seventy-eight percent of the respondents were in the Arrow-Pratt interval of -.0002 to .0003. A discriminant analysis using producer attributes and three estimated risk intervals concluded that 50 percent of the respondents could be classified in the correct risk interval.Risk and Uncertainty,

    Operational Trans-Resistance Amplifier Based Tunable Wave Active Filter

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    In this paper, Operational Trans-Resistance Amplifier (OTRA) based wave active filter structures are presented. They are flexible and modular, making them suitable to implement higher order filters. The circuits implement the resistors using matched transistors, operating in linear region, making them well suited for IC fabrication. They are insensitive to parasitic input capacitances and input resistances due to the internally grounded input terminals of OTRA. As an application, a doubly terminated third order Butterworth low pass filter has been implemented, by substituting OTRA based wave equivalents of passive elements. PSPICE simulations are given to verify the theoretical analysis

    Sensitivity of the r-process to nuclear masses

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    The rapid neutron capture process (r-process) is thought to be responsible for the creation of more than half of all elements beyond iron. The scientific challenges to understanding the origin of the heavy elements beyond iron lie in both the uncertainties associated with astrophysical conditions that are needed to allow an r-process to occur and a vast lack of knowledge about the properties of nuclei far from stability. There is great global competition to access and measure the most exotic nuclei that existing facilities can reach, while simultaneously building new, more powerful accelerators to make even more exotic nuclei. This work is an attempt to determine the most crucial nuclear masses to measure using an r-process simulation code and several mass models (FRDM, Duflo-Zuker, and HFB-21). The most important nuclear masses to measure are determined by the changes in the resulting r-process abundances. Nuclei around the closed shells near N=50, 82, and 126 have the largest impact on r-process abundances irrespective of the mass models used.Comment: 5 pages, 4 figures, accepted in European Physical Journal

    Overlapping Resonances Interference-induced Transparency: The S0→S2/S1S_0 \to S_2/S_1 Photoexcitation Spectrum of Pyrazine

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    The phenomenon of "overlapping resonances interference-induced transparency" (ORIT) is introduced and studied in detail for the S0→S2/S1S_0 \to S_2/S_1 photoexcitation of cold pyrazine (C4_4H4_4N2_2). In ORIT a molecule becomes transparent at specific wavelengths due to interferences between envelopes of spectral lines displaying overlapping resonances. An example is the S2↔S1S_2\leftrightarrow S_1 internal conversion in pyrazine where destructive interference between overlapping resonances causes the S0→S2/S1S_0 \to S_2/S_1 light absorption to disappear at certain wavelengths. ORIT may be of practical importance in multi-component mixtures where it would allow for the selective excitation of some molecules in preference to others. Interference induced cross section enhancement is also shown.Comment: 13 pages, 7 figure

    Quantum and Fisher Information from the Husimi and Related Distributions

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    The two principal/immediate influences -- which we seek to interrelate here -- upon the undertaking of this study are papers of Zyczkowski and Slomczy\'nski (J. Phys. A 34, 6689 [2001]) and of Petz and Sudar (J. Math. Phys. 37, 2262 [1996]). In the former work, a metric (the Monge one, specifically) over generalized Husimi distributions was employed to define a distance between two arbitrary density matrices. In the Petz-Sudar work (completing a program of Chentsov), the quantum analogue of the (classically unique) Fisher information (montone) metric of a probability simplex was extended to define an uncountable infinitude of Riemannian (also monotone) metrics on the set of positive definite density matrices. We pose here the questions of what is the specific/unique Fisher information metric for the (classically-defined) Husimi distributions and how does it relate to the infinitude of (quantum) metrics over the density matrices of Petz and Sudar? We find a highly proximate (small relative entropy) relationship between the probability distribution (the quantum Jeffreys' prior) that yields quantum universal data compression, and that which (following Clarke and Barron) gives its classical counterpart. We also investigate the Fisher information metrics corresponding to the escort Husimi, positive-P and certain Gaussian probability distributions, as well as, in some sense, the discrete Wigner pseudoprobability. The comparative noninformativity of prior probability distributions -- recently studied by Srednicki (Phys. Rev. A 71, 052107 [2005]) -- formed by normalizing the volume elements of the various information metrics, is also discussed in our context.Comment: 27 pages, 10 figures, slight revisions, to appear in J. Math. Phy

    Ring Expansion Of Alkylidenecarbenes Derived From Lactams, Lactones, And Thiolactones Into Strained Heterocyclic Alkynes: A Theoretical Study

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    Strained cycloalkynes are of considerable interest to theoreticians and experimentalists, and possess much synthetic value as well. Herein, a series of cyclic alkylidenecarbenes—formally obtained by replacing the carbonyl oxygen of four-, five-, and six-membered lactams, lactones, and thiolactones with a divalent carbon—were modeled at the CCSD(T)/cc-pVTZ//B3LYP/6-311+G** and CCSD(T)/cc-pVTZ//CCSD/6-311+G** levels of theory. The singlet carbenes were found to be more stable than the triplets. The strained heterocyclic alkynes formed by ring expansion of these singlet carbenes were also modeled. Interestingly, the C≡C bonds in the five-membered heterocycles, obtained from the rearrangement of β-lactam- and β-lactone-derived alkylidenecarbenes, displayed lengths intermediate between formal double and triple bonds. Furthermore, 2-(1-azacyclobutylidene)carbene was found to be nearly isoenergetic with its ring-expanded isomer, and 1-oxacyclopent-2-yne was notably higher in energy than its precursor carbene. In all other cases, the cycloalkynes were lower in energy than the corresponding carbenes. The transition states for ring-expansion were always lower for the 1,2-carbon shifts than for 1,2-nitrogen or oxygen shifts, but higher than for the 1,2-sulfur shifts. These predictions should be verifiable using carbenes bearing appropriate isotopic labels. Computed vibrational spectra for the carbenes, and their ring-expanded isomers, are presented and could be of value to matrix isolation experiments
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