None

The values of ion-atom ionization cross sections are frequently needed for many applications that utilize the propagation of fast ions through matter. When experimental data and theoretical calculations are not available, approximate formulas are frequently used. This paper briefly summarizes the most important theoretical results and approaches to cross section calculations in order to place the discussion in historical perspective and offer a concise introduction to the topic. Based on experimental data and theoretical predictions, a new fit for ionization cross sections is proposed. The range of validity and accuracy of several frequently used approximations (classical trajectory, the Born approximation, and so forth) are discussed using, as examples, the ionization cross sections of hydrogen and helium atoms by various fully stripped ions.

Prevalent authentication and authorization models for distributed systems provide for the protection of computer systems and resources from unauthorized use. The rules and policies that drive the access decisions in such systems are typically configured up front and require trust establishment before the systems can be used. This approach does not work well for computer software that moderates human-to-human interaction. This work proposes a new model for trust establishment and management in computer systems supporting collaborative work. The model supports the dynamic addition of new users to a collaboration with very little initial trust placed into their identity and supports the incremental building of trust relationships through endorsements from established collaborators. It also recognizes the strength of a users authentication when making trust decisions. By mimicking the way humans build trust naturally the model can support a wide variety of usage scenarios. Its particular strength lies in the support for ad-hoc and dynamic collaborations and the ubiquitous access to a Computer Supported Collaboration Workspace (CSCW) system from locations with varying levels of trust and security.

This report summarizes the interconnect work being performed at Delphi. Materials were chosen for this interconnect project were chosen from ferritic and austenitic stainless steels, and nickel-based superalloys. The alloys are thermally cycled in air and a wet hydrogen atmosphere. The oxide scale adherence, electrical resistance and oxidation resistance are determined after long-term oxidation of each alloy. The oxide scale adherence will be observed using a scanning electron microscope. The electrical resistance of the oxidized alloys will be determined using an electrical resistance measurement apparatus which has been designed and is currently being built. Data from the electrical resistance measurement is expected to be provided in the second quarter.

This conference paper considers how to use reaction path diagrams to better understand the output of reacting flow simulations. Briefly, these diagrams have long been used to depict the reactants and products in networks of chemical reactions. The diagrams can be generated in several ways from computer simulations of chemically reacting fluids to depict how the fluid moderates the chemistry by determining which species are brought into contact to react in quantity. The concept of a conditional diagram is introduced which depicts the reactions occurring in only a portion of the fluid domain, thus enabling comparisons between different regions of the fluid and the overall reaction network. Several examples are provided of the paths occurring in methane diffusion flames.

Radon gas concentrations have been monitored as part of the operation of a tunnel (the Exploratory Studies Facility-ESF) at Yucca Mountain to ensure worker safety. The objective of this study was to examine the potential use of the radon data to estimate large-scale formation properties of fractured tuffs. This objective was examined by developing a numerical model, based upon the characteristics of the ESF and the Topopah Spring welded (TSw) tuff unit, capable of predicting radon concentrations for prescribed ventilation conditions. The model was used to address two specific issues. First, it was used to estimate the permeability and porosity of the fractures in the TSw at the length scale of the ESF and extending tens of meters into the TSw, which surrounds the ESF. Second, the model was used to understand the mechanism leading to radon concentrations exceeding a specified level within the ESF. The mechanism controlling radon concentrations in the ESF is a function of atmospheric barometric fluctuations being propagated down the ESF along with ventilated air flow and the slight suction induced by the ventilation exhaust fans at the South Portal of the ESF. These pressure fluctuations are dampened in the TSw fracture continuum according to its …

OAK B262 Annual report. We have investigated the thermodynamics of several nanoscale systems: Iron oxides: We have completed and published heat capacity and entropy data on goethite, lepidocrocite, and maghemite, as well as measured their heats of formation. We also have enthalpy of formation data for several poorly crystalline nanophase oxides (schwertmannite, ferrihydrite, and epsilon-Fe{sub 2}O{sub 3}). The next step is to measure thermodynamic properties as a function of surface area for several oxides. CoO-MgO: Thermochemical data for bulk samples are in press. Heat capacities have been measured for CoO, MgO, and some intermediate samples. Nanosized samples at several compositions are being prepared this summer. Thin films have been prepared and some solution calorimetry done, but additional sample preparation and characterization is needed. Hydration energetics: Our setups for gas adsorption calorimetry and water immersion calorimetry are being completed. We will test them with known materials (Al{sub 2}O{sub 3}, selected zeolites) and then proceed to work on TiO{sub 2}, Fe{sub 2}O{sub 3}, and zeolites.

The Projectile Based Excavation (ProjEX) program has as its goal, the reduction of energy required for production mining and secondary breakage through the use of a projectile based excavation system. It depends on the development of a low cost family of projectiles that will penetrate and break up different types of ore/rock and a low cost electric launch system. The electric launch system will eliminate the need for high cost propellant considered for similar concepts in the past. This document reports on the program findings through the first two phases. It presents projectile design and experiment data and the preliminary design for electric launch system. Advanced Power Technologies, Inc., now BAE SYSTEMS Advanced Technologies, Inc., was forced to withdraw from the program with the loss of one of our principal mining partners, however, the experiments conducted suggest that the approach is feasible and can be made cost effective.

TART 2002 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo radiation transport code. This code can run on any modern computer. It is a complete system to assist you with input preparation, running Monte Carlo calculations, and analysis of output results. TART 2002 is also incredibly FAST; if you have used similar codes, you will be amazed at how fast this code is compared to other similar codes. Use of the entire system can save you a great deal of time and energy. TART 2002 is distributed on CD. This CD contains on-line documentation for all codes included in the system, the codes configured to run on a variety of computers, and many example problems that you can use to familiarize yourself with the system. TART 2002 completely supersedes all older versions of TART, and it is strongly recommended that users only use the most recent version of TART 2002 and its data files.

This report discusses several constitutive models for joint behavior with emphasis upon the experimental data which motivates them. Particular emphasis is placed upon data available for granite. The LDEC joint model is presented in detail and LDEC simulations using this model are compared against data from constant normal stiffness and constant normal load tests.