Non-negligible Increase Research Articles

Temperature and pressure distribution in the laser-heated diamond–anvil cell

Thermomechanical modeling of a sample assembly (sample plus pressure transmitting medium) in a laser-heated diamond–anvil cell (LHDAC) is presented. Finite elements numerical calculation afforded to obtain the temperature distribution and the induced thermal pressure field, showing that a non-negligible pressure increase (called thermal pressure) occurs in the laser-heated zone. When argon is used as a pressure transmitting medium, thermal pressure can reach 20%–30% of the normal pressure measured in the cold zone. This modeling is supported by experimental studies. It is shown that discrepancies between diamond–anvil cell and large volume press experiments on the coesite to stishovite transition are quantitatively explained by the thermal pressure effect. Moreover, thermal pressure also explains the anomalous low thermal expansion coefficient obtained by x-ray diffraction studies in LHDAC.

Band bending at semiconductor interfaces and its effect on photoemission line shapes.

We show that, contrary to intuition and under normal experimental conditions, the band bending at a semiconductor surface or interface does not strongly increase the linewidth of photoemission core-level peaks. The increase is smaller than the magnitude of the band bending, and in most cases negligible. Non-negligible increases are found only when the linewidth is smaller than and, simultaneously, the photoelectron escape depth larger than in a typical experiment.

Inlet Reverse Flow Mechanism in Axial Flow Turbomachines With Neither Stall Nor Significant Radial Flow

The cause of inlet reverse flow was studied in axial flow turbo machinery. A helical inducer, in which neither stall nor significant radial flow was observed, was selected as the experimental model. The flow between the blades was measured by a laser-Doppler velocimeter and investigated using the end-wall boundary-layer theory. Results showed that the inlet reverse flow occurs adjacent to the pressure surface between the blades in the vicinity of the casing wall. Inlet reverse flow, caused by a momentum defect in the axial direction in the boundary layer on the casing wall and a significant pressure gradient in the axial direction adjacent to the inlet blade pressure surface at partial flow rate, was found even though there was no significant radial flow or stall. In this paper, radial flow is defined as flow that causes a nonnegligible increase in the pressure on the casing wall.

On the dependence of the phase velocity of equatorial irregularities on the polarization electric field and theoretical implications

We have studied the mean Doppler shift of equatorial irregularities in the E region, using data from a coherent radar situated in Ethiopia between 1976 and 1980. We found that even though the primary two‐stream (or type I) waves are drifting at a speed close to the expected ion acoustic speed, there is a small but nonnegligible increase in the phase velocity with increasing electron drift in the electrojet. We attribute this increase to a heating of the electron gas by the large‐amplitude, low‐frequency waves that are present in the region when conditions are favorable to the production of large‐scale gradient drift instabilities. On the other hand, for the single day when the production of large‐scale gradient drift instabilities was inhibited, the behavior of the irregularities was quite different. Namely, the Doppler shift of 10‐m waves (type O waves) was usually below the linear threshold value while the spectra remained narrow and type I‐like rather than type II‐like. On the other hand, the Doppler shift followed a dependence similar to that expected from type II waves. We have tentatively attributed this type O behavior to weak mode coupling, following similar inferences from recent Condor observations made near the top of the electrojet.

Higher-order interaction-induced effects on depolarized light scattering from fluids of optically anisotropic molecules

The effect of higher-order terms in dipole-induced dipole (DID) interactions on the depolarized light scattering intensity in liquid oxygen is calculated using molecular dynamics computer simulation. The total induced dipole moment in the system is evaluated iteratively. Inclusion of multiple DID interaction terms is found to lead to a non-negligible increase in the depolarized intensity over the first-order result.

Program behavior prediction and prepaging

The design and evaluation of a prepaging technique is presented. It consists in the preloading, at instants at which page-faults occur, of those pages whose use in the future is the most likely. These pages are determined as a function of an a-priori knowledge of program behavior. We shall first present two tools for predicting that behavior. The first is based on a Markov memory reference transition model, the second on a semi-Markov model of page-fault transitions. Both methods are successively experimented by a paging algorithm allowing prepaging. Experimentation shows that prepaging can significantly improve the performance of the paging algorithm, especially when the prediction is based on the transitions between page-faults. The sensitivity of prepaging performance to various working conditions is tested. Implementation of prepaging is examined and is shown to be feasible without the use of special hardware devices. The study is completed by an evaluation of the influence of prepaging on global system performance. Some common cases of system architecture experimentation show a non-negligible increase in CPU utilization.

Symmetric and asymmetric fission in electron induced fission of 232Th

We have measured fragment kinetic energies in electron induced fission of 232Th for electron energies in the range 7 MeV ≦ E e ≦ 66 MeV. The relative contribution of the distribution peak associated with high fragment kinetic energies decreases continuously with electron energy. This is interpreted as a relative increase of the symmetric fission yield as compared to the asymmetric fission yield; this fact in turn indicates a non-negligible increase in the average excitation of the fissioning nucleus, with the energy of the bombarding electrons, even above the giant dipole resonance.

Effect of Many Particle, Many Hole States in 16O on Positive Pion Photoproduction

The 1p–1h odd parity T = 1 states of 16N (2−, 0−, 3−, 1−) are amended to include the 3p–3h configuration admixtures consistent with the choice of a 16O ground state containing 2p–2h correlations. Estimates indicate that these 3p–3h admixtures result in a nonnegligible increase or decrease of the cross sections depending upon the amount of 2p–2h correlations in the ground state of 16O.