3,124 research outputs found

    Bubble Bursting in Molten Glass

    Get PDF

    Generalized Pauli-Villars regularization for undoubled lattice fermions

    Full text link
    A manifestly gauge invariant formulation of chiral theories with fermions on the lattice is developed. It combines SLAC lattice derivative \cite{DWY}, \cite{ACS}, \cite{S} and generalized Pauli-Villars regularization \cite{FS}. The theory is free of fermion doubling, requires only local gauge invariant counterterms and produces correct results when applied to exactly solvable two dimensional models.Comment: 10 pages LATEX fil

    Sheet SK 00 SW and SK 00 SE ALDRIDGE - BROWNHILLS : part of 1:50 000 Sheet 154 (Lichfield)

    Get PDF
    This report embodies some of the results of a study commissioned by the Department of the Environment in 1983 to provide a geological information base, to enable informed consideration to be given to development proposals for the Aldridge - Brownhills area. It is mainly concerned with hydrogeology, subsidence and bulk minerals resources.There is a substantial introductory section on general geology, to give the geological context of these planning-related aspects

    Stochastic ϕ4−\phi^4-Theory in the Strong Coupling Limit

    Full text link
    The stochastic ϕ4\phi^4-theory in d−d-dimensions dynamically develops domain wall structures within which the order parameter is not continuous. We develop a statistical theory for the ϕ4\phi^4-theory driven with a random forcing which is white in time and Gaussian-correlated in space. A master equation is derived for the probability density function (PDF) of the order parameter, when the forcing correlation length is much smaller than the system size, but much larger than the typical width of the domain walls. Moreover, exact expressions for the one-point PDF and all the moments are given. We then investigate the intermittency issue in the strong coupling limit, and derive the tail of the PDF of the increments ϕ(x2)−ϕ(x1)\phi(x_2) - \phi(x_1). The scaling laws for the structure functions of the increments are obtained through numerical simulations. It is shown that the moments of field increments defined by, Cb=C_b=, behave as ∣x1−x2âˆŁÎŸb|x_1-x_2|^{\xi_b}, where Οb=b\xi_b=b for b≀1b\leq 1, and Οb=1\xi_b=1 for b≄1b\geq1Comment: 22 pages, 6 figures. to appear in Nuclear. Phys.

    Structural reliability-based assessment of Nigerian Anogeissus schimperi timber bridge beam in shear and bearing forces

    Get PDF
    This research investigates the reliability of Anogeissus schimperi timber specie grown in North Western Nigeria as a bridge beam in shear and bearing forces. Specimens for laboratory tests were prepared using the timber specie in accordance with BS 373 (1957). Tests were carried out to determine the physical and mechanical properties at 12% moisture content in line with BS 5268 (2002). Statistical analysis was carried out using strength properties obtained and the specie was classified to strength class D60, confirmed to be Hardwood. Anogeissus schimperi timber bridge beam was designed in accordance to BS5268 (2002), using deterministicapproach. While, reliability analysis to confirm the safety level of the timber bridge beam designed was carried out using constant failure rate model in accordance with Jimoh, (2018). Sensitivity analysis to ascertain the safety margin of a simply supported timber bridge beam subjected to Shear and bearing by varying the span, depth, width and live load was carried out. Results of reliability analysis showed that Anogeissus schimperi met the minimum reliability index of 0.5 under ultimate state of loading in Shear and bearing. Safety index was found to be directly proportional to the depth and width but inversely proportional to the span and live loadof the timber bridge beam during Sensitivity Analysis. The result confirmed that Anogeissus schimperi specie from north western Nigeria at 400mm depth, 150mm breadth and 5000mm span under ultimate limit state loading in Shear and bearing can be used as a reliable timber bridge beam material. Keywords: Bridge Beam, Nigerian Anogeissus schimperi Reliability, Structural Material, Timber, Ultimate Limit State

    Reliability-Based Design of Solid and Nail-jointed I-Section of Nigerian-Grown African Birch (Anogeissus leiocarpus) Timber Column

    Get PDF
    The Nigerian-grown African birch timber was used to assemble I- section specimens which were tested in the laboratory for their compressive strengths. Solid square sections of the same specie were similarly tested for an apt comparison of results. A structural reliability analysis was carried out for these two sections to ascertain their performance as structural timber columns using statistical parameters that were determined for the deterministic design of the timber column. A FORTRAN-based program was also developed and used for the reliability analysis of the Nigerian-grown African birch columns designed to ascertain their level of safety using First-Order Reliability Method (FORM). The ‘I’- section was found unsafe to bear the design load unlike its corresponding solid section. An identified I- section of (100 x 400mm) was found adequate (with Pf =1.22 x 10-02) whose compressive resistance corresponds to (200 x 100mm) of the solid section (with Pf =7.76 x 10-02) which is practically half the dimension of the I-section. This shows that the solid section has a capacity twice that of the ‘I’- section of equal dimensions. However, considering the minimum dimension of the of the two sections capable of supporting the design load, the ‘I’- section is more economical than the solid section since it offers a less effective area of 11,200mm2 compared to the solid section with an effective area of 20,000mm2 . The ‘I’-section also showed a higher capacity to bear the Euler load with greater lengths than the solid section because of its greater radius of gyration and rigidity value and would be rather preferable for long columns than the solid section. Considering the limited availability of larger dimensions of solid sections, the built-up I- section would be more relevant where large sized sections are required.Keywords: Solid section, Compressive capacity, Built-up sections, Reliability, Probability of failure (Pf

    Stoke-on-Trent: a geological background for planning and development

    Get PDF
    This study, carried out between 1988 and 1990, was commissioned by the Department of the Environment (DOE) and funded jointly by the Department and the British Geological Survey (BGS). Its main aim was to make a synthesis of geological data relevant to planning of land-use and development in the Stoke-on-Trent area. This report is specifically written for planners and there has been an attempt to avoid complex geological terms. Besides text illustrations the report includes ten thematic maps at a common scale of 1 :25 000. An additional volume concentrates on engineering geology for site investigation companies. Seven further short reports feature geological details of separate 1: 10 000 sheets, couched in more technical language

    Validation of the Virtual Reality Everyday Assessment Lab (VR-EAL):An immersive virtual reality neuropsychological battery with enhanced ecological validity

    Get PDF
    International audienceObjective: The assessment of cognitive functions such as prospective memory, episodic memory, attention, and executive functions benefits from an ecologically valid approach to better understand how performance outcomes generalize to everyday life. Immersive virtual reality (VR) is considered capable of simulating real-life situations to enhance ecological validity. The present study attempted to validate the Virtual Reality Everyday Assessment Lab (VR-EAL), an immersive VR neuropsychological battery, against an extensive paper-andpencil neuropsychological battery. Methods: Forty-one participants (21 females) were recruited: 18 gamers and 23 non-gamers who attended both an immersive VR and a paper-and-pencil testing session. Bayesian Pearson correlation analyses were conducted to assess construct and convergent validity of the VR-EAL. Bayesian t-tests were performed to compare VR and paper-and-pencil testing in terms of administration time, similarity to real life tasks (i.e., ecological validity), and pleasantness. Results: VR-EAL scores were significantly correlated with their equivalent scores on the paper-and-pencil tests. The participants' reports indicated that the VR-EAL tasks were significantly more ecologically valid and pleasant than the paper-and-pencil neuropsychological battery. The VR-EAL battery also had a shorter administration time. Conclusion: The VR-EAL appears as an effective neuropsychological tool for the assessment of everyday cognitive functions, which has enhanced ecological validity, a highly pleasant testing experience, and does not induce cybersickness

    Linear friction weld process monitoring of fixture cassette deformations using empirical mode decomposition

    Get PDF
    Due to its inherent advantages, linear friction welding is a solid-state joining process of increasing importance to the aerospace, automotive, medical and power generation equipment industries. Tangential oscillations and forge stroke during the burn-off phase of the joining process introduce essential dynamic forces, which can also be detrimental to the welding process. Since burn-off is a critical phase in the manufacturing stage, process monitoring is fundamental for quality and stability control purposes. This study aims to improve workholding stability through the analysis of fixture cassette deformations. Methods and procedures for process monitoring are developed and implemented in a fail-or-pass assessment system for fixture cassette deformations during the burn-off phase. Additionally, the de-noised signals are compared to results from previous production runs. The observed deformations as a consequence of the forces acting on the fixture cassette are measured directly during the welding process. Data on the linear friction-welding machine are acquired and de-noised using empirical mode decomposition, before the burn-off phase is extracted. This approach enables a direct, objective comparison of the signal features with trends from previous successful welds. The capacity of the whole process monitoring system is validated and demonstrated through the analysis of a large number of signals obtained from welding experiments

    Phase transitions in two-dimensional anisotropic quantum magnets

    Full text link
    We consider quantum Heisenberg ferro- and antiferromagnets on the square lattice with exchange anisotropy of easy-plane or easy-axis type. The thermodynamics and the critical behaviour of the models are studied by the pure-quantum self-consistent harmonic approximation, in order to evaluate the spin and anisotropy dependence of the critical temperatures. Results for thermodynamic quantities are reported and comparison with experimental and numerical simulation data is made. The obtained results allow us to draw a general picture of the subject and, in particular, to estimate the value of the critical temperature for any model belonging to the considered class.Comment: To be published on Eur. Phys. J.
    • 

    corecore