A detailed model for the dynamic resistivity of an exploding conductor presents many difficulties. An electrically-exploded conductor undergoes significant hydrodynamic expansion as it is heated. Resistivity is a function of both the temperature and density of a conductor and realistic models for resistivity over the range of parameter space experienced by an exploding conductor are quite complex. See for example, the model of Lee and More (1984). Calculation of the hydrodynamic expansion of the conductor during and subsequent to the explosion is likewise dependent on detailed knowledge of the equation of state for the conductor in a range where few experimental data exist. A further complication is the strong magnetic field which couples the hydrodynamic expansion to the currents flowing in the expanding material. In spite of the difficulties, progress is being made on detailed modeling of fuses and exploding conductors (Lidemuth and co-workers, 1985). A simpler approach has proved to be quite useful for modeling the electrical behavior of exploding bridgewire and slapper detonators and for modeling the explosionss of large conductors exploded with large capacitor banks. In the work described here, a simple, empirical model was developed which can be expressed as a closed-form algebraic expression involving four …

A method is developed for predicting cutter forces, temperatures, and wear on PDC bits as well as integrated bit performance parameters such as weight-on-bit (WOB), drilling torque, and bit imbalance. A computer code called PDCWEAR has been developed to make this method available as a tool for general bit design. The method uses single-cutter data to provide a measure of rock drillability and employs theoretical considerations to account for interaction among closely spaced cutters on the bit. Experimental data are presented to establish the effects of cutter size and wearflat area on the forces that develop during rock cutting. Waterjet assistance is shown to significantly reduce cutting forces, thereby extending bit life and reducing WOB and torque requirements in hard rock. The effects of bit profile, cutter placement density, bit rotary speed, and wear mode on bit life and drilling performance are investigated. 21 refs., 34 figs., 4 tabs.

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.

Over a wide range of incident energies, the total cross section and angular distributions for elastic scattering of neutrons from nuclei in these mass regions are analyzed using the spherical-optical-statistical model. The effect of a real-surface-peaked potential, predicted by dispersion relations, is considered. It is found that when the data on a given nucleus between say, 4.5 and 10 MeV, are analyzed simultaneously one obtains a smooth energy variation of the optical model parameters. Moreover, this parameterization may be used to predict, quite accurately, at least the total cross sections up to 20 MeV. The parameters characterizing the model are quite different in the two mass regions. However, a comparison of the optical model results for (/sup 89/Y and /sup 93/Nb indicates that near A = 90 the real well parameters are nearly the same for the two nuclei and that the volume integrals of the imaginary potentials are similar. 16 refs., 9 figs., 2 tabs.

Photon (Gamma-Ray) KERMA factors calculated from the LLNL EGDL (Evaluated Gamma-Ray Data Library) file are tabulated for the elements from Z=1 to Z=30 and for 15 composite materials. The KERMA factors are presented for 191 energy groups over the incident photon energy range from 100 eV to 100 MeV. 3 refs.