165,829 research outputs found
A theoretical analysis of the Power of Biased Coin Designs
No full textOutlining some recently obtained results of Hu and Rosenberger [2003. Optimality, variability, power: evaluating responseadaptive
randomization procedures for treatment comparisons. J. Amer. Statist. Assoc. 98, 671–678] and Chen [2006. The power of
Efron’s biased coin design. J. Statist. Plann. Inference 136, 1824–1835] on the relationship between sequential randomized designs
and the power of the usual statistical procedures for testing the equivalence of two competing treatments, the aim of this paper is to
provide theoretical proofs of the numerical results of Chen [2006. The power of Efron’s biased coin design. J. Statist. Plann. Inference
136, 1824–1835]. Furthermore, we prove that the Adjustable Biased Coin Design [Baldi Antognini A., Giovagnoli, A., 2004. A
new “biased coin design” for the sequential allocation of two treatments. J. Roy. Statist. Soc. Ser. C 53, 651–664] is uniformly more
powerful than the other “coin” designs proposed in the literature for any sample size
Far-Field Boundary Conditions for Calculation of Hole-Drilling Residual Stress Calibration Coefficients
No full textThe Hole-Drilling method for residual stress measurement, both in its standard version based on strain gauge rosettes (ASTM E837-08e1 2008) and its derivative using optical methods for estimating the displacement field around the hole (Baldi (2005) J Eng Mater Technol 127(2):165–169; Schajer and Steinzig (2005) Exp Mech 45(6):526–532; Schajer (2010) Exp Mech 50(2):159–168), relies on numerical calibrated coefficients (A and B) to correlate the experimentally acquired strains (displacements) with residual stress components. To estimate the A and B coefficients, two FEM (Finite Element Method) computations are required, the former related to a hydrostatic stress state, the latter to a pure shear case. Both can be implemented using either a semi-analytical approach (i.e. an axis-symmetric mesh expanded in the tangential direction using a Fourier series) or a tri-dimensional mesh, usually exploiting the double symmetry of the problem. Whatever the approach selected, the definition of constraints to be applied to the outer boundary is critical because the hole-drilling method assumes an infinite plate, thus both the usual solutions—fully constrained or free boundaries—are unable to correctly describe the theoretical situation. In the following, the problem of correct simulation of the infinite domain will be discussed and two simple and effective solutions will be proposed
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray source
No full textWe present an analysis of the extreme obscuration variability observed during an XMM–Newton 5-d continuous monitoring of the active galactic nuclei (AGN) in NGC 1365. The source was in a reflection-dominated state in the first ∼1.5 d, then a strong increase in the 7–10 keV emission was observed in ∼10 h, followed by a symmetric decrease. The spectral analysis of the different states clearly shows that this variation is due to an uncovering of the X-ray source. From this observation, we estimate a size of the X-ray source DS < 1013 cm, a distance of the obscuring clouds R∼ 1016 cm and a density n∼ 1011 cm−3. These values suggest that the X-ray absorption/reflection originates from the broad-line region clouds. This is also supported by the resolved width of the iron narrow Kα emission line, consistent with the width of the broad Hβ line
Bifurcation and secondary bifurcation of heavy periodic hydroelastic travelling waves
No full textThe existence question for two-dimensional symmetric steady waves travelling on the surface of a deep ocean beneath a heavy elastic membrane is analyzed as a problem in bifurcation theory. The behaviour of the two-dimensional cross-section of the membrane is modelled as a thin (unshearable), heavy, hyperelastic extensible rod, and the fluid beneath is supposed to be in steady two-dimensional irrotational motion under gravity. When the wavelength has been normalized to be 2π, and when gravity and the density of the undeformed membrane are prescribed, there are two free parameters in the problem: the speed of the wave and the drift velocity of the membrane. It is observed that the problem, when linearized about uniform horizontal flow, has at most two independent solutions for any values of the parameters. When the linearized problem has only one normalized solution, it is shown that the full nonlinear problem has a sheet of solutions consisting of a family of curves bifurcating from simple eigenvalues. Here one of the problem's parameters is used to index a family of bifurcation problems in which the other is the bifurcation parameter. When the linearized problem has two solutions, with wave numbers k and l such that max{k,l}/min{k,l} ∉ Z it is shown that there are three two-dimensional sheets of bifurcating solutions. One consists of "special" solutions with minimal period 2π/k; another consists of "special" solutions with minimal period 2π/l; and the third, apart from those on the curves where it intersects the "special" sheets, consists of "general" solutions with minimal period 2π. The two sheets of "special" solutions are rather similar to those that occur when the linearized problem has only one solution. However, points where the first sheet or the second sheet intersects the third sheet are period-multiplying (or symmetry-breaking) secondary bifurcation points on primary branches of "special" solutions. This phenomenon is analogous to that of Wilton ripples, which arises in the classical water-wave problem when the surface tension has special values. In the case of Wilton ripples, the coefficient of surface tension and the wave speed are the problem's two parameters. In the present context, there are two speed parameters, meaning that the membrane elasticity does not need to be highly specified for this symmetry-breaking phenomenon to occur
A transient kinetic study of VOC complete oxidation over a noble metal catalyst
No full textODOURS&VOCS
High-rate J-testing of toughened polyamide 6/6: Applicability of the load separation criterion and the normalization method
No full textThis paper examines the applicability of the load separation criterion and the normalization method in determining JR curve of a toughened polyamide 6/6 at high loading rates (1 m/s). The analysis of procedure problems associated to this high experimental rate is performed. The results obtained using the normalization method are then compared with those measured via multi-specimen testing procedures proposed by ESIS (Technical Committee 4). The results show that, unlike low loading rate tests, the presence of the oscillations in the load vs displacement traces, due to the inertial effects produced during the impact, complicate considerably the elaboration of the data, with particular reference to the identification of the separable blunting region. The comparison of JIc values obtained according to the different procedures examined indicates that the values of JIc = J0.2 (taken at 0.2 mm crack growth) are in good agreement, whereas consistent differences among the values of JIc = J-blunting (taken at the blunting line) are observed
Steady periodic water waves under nonlinear elastic membranes
No full textThis is a study of two-dimensional steady periodic travelling waves on the surface of an infinitely deep irrotational ocean, when the top streamline is in contact with a membrane which has a nonlinear response to stretching and bending, and the pressure in the air above is constant. It is not supposed that the waves have small amplitude. The problem of existence of such waves is addressed using methods from the calculus of variations. The analysis involves the Hilbert transform and a Riemann-Hilbert formulation
Murder on the mountain: author talk with Peter J. Wosh
No full textAuthor talk by Peter J. Wosh on May 5th, 2022, on his book, "Murder on the Mountain: crime, passion, and punishment in gilded age New Jersey.
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