Energy spectra of metastable oxygen atoms produced by electron impact dissociation of O2

Kinetic energies of metastable oxygen atoms formed by electron impact dissociation of oxygen and measured in time of flight experimen

Production of CO(a 3 Pi) and other metastable fragments by electron impact dissociation of CO2

Dissociative excitation of CO(a 3 Pi) and other metastable fragments such as O(5S) produced by electron impact on CO

Excitation of the metastable E(3 Sigma g plus) state of N2 by electron impact

The contribution of the N2(E(3 Sigma g plus)) state to the total metastable excitation function of N2 assessed on the basis of time-of-flight studies of metastable nitrogen molecules. The cross section for electron impact excitation state was determined in the domain of the resonance form threshold (11.87 eV) to an energy of about 13 eV. The maximum value of the cross section was found to be (7.0 + or - 4.0) x 10 to the -18th power sq cm at an energy of 12.2 eV. The measurement was made absolute by using the previously determined yield of the metastable detector, the lifetime of the E state, and by eliminating the energy spread in the electron beam from the raw data. The half-width (FWHM) of the resonance-like excitation function near threshold was found to be about 0.4 eV. No substantial evidence was obtained from the present data for the presence of the nonresonant part of the excitation function for the state studied

A mass spectrometer observation of NO in an auroral arc

NO measurement in auroral arc by mass spectrometer onboard Aerobee rocke

Energy conservation during remeshing in the analysis of dynamic fracture

The analysis of (dynamic) fracture often requires multiple changes to the discretisation during crack propagation. The state vector from the previous time step must then be transferred to provide the initial values of the next time step. A novel methodology based on a least‐squares fit is proposed for this mapping. The energy balance is taken as a constraint in the mapping, which results in a complete energy preservation. Apart from capturing the physics better, this also has advantages for numerical stability. To further improve the accuracy, Powell‐Sabin B‐splines, which are based on triangles, have been used for the discretisation. Since urn:x-wiley:nme:media:nme6142:nme6142-math-0001 continuity of the displacement field holds at crack tips for Powell‐Sabin B‐splines, the stresses at and around crack tips are captured much more accurately than when using elements with a standard Lagrangian interpolation, or with NURBS and T‐splines. The versatility and accuracy of the approach to simulate dynamic crack propagation are assessed in two case studies, featuring mode‐I and mixed‐mode crack propagation

Asymptotic Expansions for the Conditional Sojourn Time Distribution in the M/M/1M/M/1-PS Queue

We consider the $M/M/1$ queue with processor sharing. We study the conditional sojourn time distribution, conditioned on the customer's service requirement, in various asymptotic limits. These include large time and/or large service request, and heavy traffic, where the arrival rate is only slightly less than the service rate. The asymptotic formulas relate to, and extend, some results of Morrison \cite{MO} and Flatto \cite{FL}.Comment: 30 pages, 3 figures and 1 tabl

Finite thickness of shear bands in frictional viscoplasticity and implications for lithosphere dynamics

Permanent deformations in the lithosphere can occur in the brittle as well as in the ductile domain. For this reason, the inclusion of viscous creep and frictional plastic deformation is essential for geodynamic models. However, most currently available models of frictional plasticity are rate independent and therefore do not incorporate an internal length scale, which is an indispensible element for imposing a finite width of localized shear zones. Therefore, in computations of localization, either analytical or numerical, resulting shear zone widths tend to zero. In numerical computations, this manifests itself in a severe mesh sensitivity. Moreover, convergence of the global iterative procedure to solve the nonlinear processes is adversely affected, which negatively affects the reliability and the quality of predictions. The viscosity that is inherent in deformation processes in the lithosphere can, in principle, remedy this mesh sensitivity. However, elasto‐viscoplastic models that are commonly used in geodynamics assume a series arrangement of rheological elements (Maxwell‐type approach), which does not introduce an internal length scale. Here, we confirm that a different rheological arrangement that puts a damper in parallel to the plastic slider (Kelvin‐type approach) introduces an internal length scale. As a result, pressure and strain and strain rate profiles across the shear bands converge to finite values upon decreasing the grid spacing. We demonstrate that this holds for nonassociated plasticity with constant frictional properties and with material softening with respect to cohesion. Finally, the introduction of Kelvin‐type viscoplasticity also significantly improves the global convergence of nonlinear solvers