We studied simultaneously the 4 He(e, e p), 4 He(e, e pp), and 4 He(e, e pn) reactions at Q 2 = 2 (GeV/c) 2 and xB > 1, for an (e, e p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A = 2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum, in a region where the nucleon-nucleon (N N ) force is expected to change from predominantly tensor to repulsive. The abundance of neutron-proton pairs is reduced as the nucleon momentum increases beyond ∼500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum. Our data are compared with calculations of two-nucleon momentum distributions in 4 He and discussed in the context of probing the elusive repulsive N N force.

In addition to the well-known positive space charge, electron irradiation of MOS capacitors with 25-keV electrons is shown to introduce additional uncharged electron traps into the oxide layer. These traps persist after most of the positively charged defects have been removed by the usual low-temperature (~ 0c) anneals. Their presence after this anneal is determined by injecting hot electrons into the oxide where they are captured by existing defects. The effective trap densities increase with increasing electron fluence and are reduced by forming-gas anneals at temperatures in excess of 500°C. Observed electron-capture cross sections are between 10-15 and 10-18 cm 2 • The residual radiation damage in oxides exposed to 10-4 Ccm-2 of 25-keV electrons and subsequently annealed at 4OQ°C results in an additional neutral density of 5 X 1011 trapscm-2 with cross sections distributed over the above range. Electron-trapping cross sections and effective trap densities associated with this damage are found to be identical at 77 and 295 K. The traps are possibly associated with dipolar defects formed when valence electrons localize around an ion after the bonds are broken.

Smoothed particle hydrodynamics (SPH) is aLagrangian method based on a meshless discretization of partial differential equations. In this review, we present SPH discretization of the Navier-Stokes and advection-diffusionreaction equations, implementation of various boundary conditions, and time integration of the SPH equations, and we discuss applications of the SPH method for modeling pore-scale multiphase flows and reactive transport in porous and fractured media.

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We report the first measurement of the target single-spin asymmetry, A y , in quasielastic scattering from the inclusive reaction 3 He ↑ ðe; e 0 Þ on a 3 He gas target polarized normal to the lepton scattering plane.

To achieve the performance of a mechanism to a higher degree of accuracy requires that the elastic deformations of a member in a mechanism under dynamic loading conditions be taken into account. Coupled nonlinear governing partial differential equations have been derived for transverse and longitudinal vibrations of an elastic connecting rod in a slider-crank mechanism operating at high speed conditions. The derived coupled governing nonlinear partial differential equations of motion were transformed into ordinary differential equations by use of the Kantorovich method and the method of weighted residuals. The resulting coupled ordinary differential equations were solved numerically by use of the piecewise polynomial method and the fourth-order Runge-Kutta method. The dynamic response of the system has been investigated on the basis of natural frequencies of the first mode free vibrations, the ratios of the length of crank to the length of connecting rod, viscous damping, and rotating speeds of crank. These parameters can be used by the designer to predict the vibrations of an elastic mechanism under high-speed conditions.

The parity-violating asymmetries between a longitudinally polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep-inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published earlier, but are presented here in more detail