5,632 research outputs found

    Don’t Look Back: The Paradoxical Role of Recording in the Fashion Design Process

    Get PDF
    Although there is little systematic research in academia or industry examining design processes in Fashion, anecdotal evidence, based on self- reports and observations, suggests that designers very rarely record the process of designing. Conversely, benefits and requirements of recording the design process within other domains, such as Engineering and Architecture, are well supported in the literature. This paper attempts to explore the dichotomy of recording and non-recording practice across these fields through a review of the literature, semi-structured interviews and a report on one case study in particular, drawing out further detail. Commonalities and differences are identified and new directions for research proposed

    Lamp reliability studies for improved satellite rubidium frequency standard

    Get PDF
    In response to the premature failure of Rb lamps used in Rb atomic clocks onboard NAVSTAR GPS satellites experimental and theoretical investigations into their failure mechanism were initiated. The primary goal of these studies is the development of an accelerated life test for future GPS lamps. The primary failure mechanism was identified as consumption of the lamp's Rb charge via direct interaction between Rb and the lamp's glass surface. The most effective parameters to accelerate the interaction between the Rb and the glass are felt to be RF excitation power and lamp temperature. Differential scanning calorimetry is used to monitor the consumption of Rb within a lamp as a function of operation time. This technique yielded base line Rb consumption data for GPS lamps operating under normal conditions

    In-situ measurements of dendrite tip shape selection in a metallic alloy

    Full text link
    The size and shape of the primary dendrite tips determine the principal length scale of the microstructure evolving during solidification of alloys. In-situ X-ray measurements of the tip shape in metals have been unsuccessful so far due to insufficient spatial resolution or high image noise. To overcome these limitations, high-resolution synchrotron radiography and advanced image processing techniques are applied to a thin sample of a solidifying Ga-35wt.%In alloy. Quantitative in-situ measurements are performed of the growth of dendrite tips during the fast initial transient and the subsequent steady growth period, with tip velocities ranging over almost two orders of magnitude. The value of the dendrite tip shape selection parameter is found to be σ∗=0.0768\sigma^* = 0.0768, which suggests an interface energy anisotropy of Δ4=0.015\varepsilon_4 = 0.015 for the present Ga-In alloy. The non-axisymmetric dendrite tip shape amplitude coefficient is measured to be A4≈0.004A_4 \approx 0.004, which is in excellent agreement with the universal value previously established for dendrites.Comment: 9 pages, 6 figures, submitted to "Physical Reviews Materials

    A deterministic cavity-QED source of polarization entangled photon pairs

    Get PDF
    We present two cavity quantum electrodynamics proposals that, sharing the same basic elements, allow for the deterministic generation of entangled photons pairs by means of a three-level atom successively coupled to two single longitudinal mode high-Q optical resonators presenting polarization degeneracy. In the faster proposal, the three-level atom yields a polarization entangled photon pair via two truncated Rabi oscillations, whereas in the adiabatic proposal a counterintuitive Stimulated Raman Adiabatic Passage process is considered. Although slower than the former process, this second method is very efficient and robust under fluctuations of the experimental parameters and, particularly interesting, almost completely insensitive to atomic decay.Comment: 5 pages, 5 figure

    On single-photon quantum key distribution in the presence of loss

    Get PDF
    We investigate two-way and one-way single-photon quantum key distribution (QKD) protocols in the presence of loss introduced by the quantum channel. Our analysis is based on a simple precondition for secure QKD in each case. In particular, the legitimate users need to prove that there exists no separable state (in the case of two-way QKD), or that there exists no quantum state having a symmetric extension (one-way QKD), that is compatible with the available measurements results. We show that both criteria can be formulated as a convex optimisation problem known as a semidefinite program, which can be efficiently solved. Moreover, we prove that the solution to the dual optimisation corresponds to the evaluation of an optimal witness operator that belongs to the minimal verification set of them for the given two-way (or one-way) QKD protocol. A positive expectation value of this optimal witness operator states that no secret key can be distilled from the available measurements results. We apply such analysis to several well-known single-photon QKD protocols under losses.Comment: 14 pages, 6 figure

    Tuning Heavy Fermion Systems into Quantum Criticality by Magnetic Field

    Full text link
    We discuss a series of thermodynamic, magnetic and electrical transport experiments on the two heavy fermion compounds CeNi2Ge2 and YbRh2Si2 in which magnetic fields, B, are used to tune the systems from a Non-Fermi liquid (NFL) into a field-induced FL state. Upon approaching the quantum-critical points from the FL side by reducing B we analyze the heavy quasiparticle (QP) mass and QP-QP scattering cross sections. For CeNi2Ge2 the observed behavior agrees well with the predictions of the spin-density wave (SDW) scenario for three-dimensional (3D) critical spin-fluctuations. By contrast, the observed singularity in YbRh2Si2 cannot be explained by the itinerant SDW theory for neither 3D nor 2D critical spinfluctuations. Furthermore, we investigate the magnetization M(B) at high magnetic fields. For CeNi2Ge2 a metamagnetic transition is observed at 43 T, whereas for YbRh2Si2 a kink-like anomaly occurs at 10 T in M vs B (applied along the easy basal plane) above which the heavy fermion state is completely suppressed.Comment: 15 pages, 8 figures, submitted to Journal of Low Temperature Physics, special Series on "High Magnetic Field Facilities

    Is there a reentrant glass in binary mixtures?

    Full text link
    By employing computer simulations for a model binary mixture, we show that a reentrant glass transition upon adding a second component only occurs if the ratio α\alpha of the short-time mobilities between the glass-forming component and the additive is sufficiently small. For α≈1\alpha \approx 1, there is no reentrant glass, even if the size asymmetry between the two components is large, in accordance with two-component mode coupling theory. For αâ‰Ș1\alpha \ll 1, on the other hand, the reentrant glass is observed and reproduced only by an effective one-component mode coupling theory.Comment: 4 pages, 3 figure

    Origin of non-exponential relaxation in a crystalline ionic conductor: a multi-dimensional 109Ag NMR study

    Full text link
    The origin of the non-exponential relaxation of silver ions in the crystalline ion conductor Ag7P3S11 is analyzed by comparing appropriate two-time and three-time 109Ag NMR correlation functions. The non-exponentiality is due to a rate distribution, i.e., dynamic heterogeneities, rather than to an intrinsic non-exponentiality. Thus, the data give no evidence for the relevance of correlated back-and-forth jumps on the timescale of the silver relaxation.Comment: 4 pages, 3 figure

    Financial Competence and Expectations Formation: Evidence from Australia

    Full text link
    We study the financial competence of Australian retirement savers using self-assessed and quantified measures. Responses to financial literacy questions show large variation and compare poorly with some international surveys. Basic and sophisticated financial literacy vary significantly with most demographics, self-assessed financial competence, income, superannuation accumulation and net worth. General numeracy scores are largely constant across gender, age, higher education and income. Financial competence also significantly affects expectations of stock market performance. Using a discrete choice model, we show that individuals with a higher understanding of risk, diversification and financial assets are more likely to assign a probability to future financial crises rather than expressing uncertainty. © 2011 The Economic Society of Australia
    • 

    corecore