In this paper, we present a simple annealing procedure (which we refer to as ''flash-annealing'' because of short duration) that results in the formation of an ultralow friction surface film on vanadium diboride (VB{sub 2}) surfaces. This annealing is done in a box furnace at 800 C for a period of 5 min. During annealing, the exposed surface of the VB{sub 2} undergoes oxidation and forms a layer of boron oxide (B{sub 2}O{sub 3}). In open air, the B{sub 2}O{sub 3} layer reacts spontaneously with moisture and forms a boric acid (H{sub 3}BO{sub 3}) film. The friction coefficient of a 440C steel pin against this H{sub 3}BO{sub 3} film is {approx}0.05, compared to 0.8 against the as-received VB{sub 2}. Based on Raman spectroscopy and electron microscopy studies, we elucidate the ultralow friction mechanism of the flash-annealed VB{sub 2} surfaces.

Structural dynamic testing is concerned with the estimation of system properties, including frequency response functions and modal characteristics. These properties are derived from tests on the structure of interest, during which excitations and responses are measured and Fourier techniques are used to reduce the data. The inputs used in a test are frequently random, and they excite random responses in the structure of interest When these random inputs and responses are analyzed they yield estimates of system properties that are random variable and random process realizations. Of course, such estimates of system properties vary randomly from one test to another, but even when deterministic inputs are used to excite a structure, the estimated properties vary from test to test. When test excitations and responses are normally distributed, classical techniques permit us to statistically analyze inputs, responses, and some system parameters. However, when the input excitations are non-normal, the system is nonlinear, and/or the property of interest is anything but the simplest, the classical analyses break down. The bootstrap is a technique for the statistical analysis of data that are not necessarily normally distributed. It can be used to statistically analyze any measure of input excitation or response, or any system …

Fifty nanosecond pulses of visible light have been used to produce hard, hydrogen-free diamond-like-carbon (DLC) films at irradiances between 5 x 10{sup 8} and 5 x 10{sup 10} W/cm{sup 2} The films were characterized by a number of techniques including: Raman spectroscopy, Electron Energy Loss Spectroscopy (EELS), atomic force microscopy, and spectroscopic ellipsometry. The cost for manufacturing DLC with high average power, high-pulse repetition frequency, visible light is low enough to compete with other diamond thin film production methods.

The numerical simulation of chemically reacting flows is a topic that has attracted a great deal of current research. At the heart of numerical reactive flow simulations are large sets of coupled, nonlinear partial differential equations (PDEs). Due to the stiffness that is usually present, explicit time differencing schemes are not used despite their inherent simplicity and efficiency on parallel and vector machines, since these schemes require prohibitively small numerical stepsizes. Implicit time differencing schemes, although possessing good stability characteristics, introduce a great deal of computational overhead necessary to solve the simultaneous algebraic system at each timestep. This paper proposes an algorithm based on a preconditioned time differencing scheme. The algorithm is explicit and permits a large stable time step. A study of the algorithm's performance on a parallel architecture is presented.

The carbonate fuel cell promises highly efficient, cost-effective, environmentally superior power generation from pipeline natural gas, coal gas, biogas, and other gaseous and liquid fuels. ERC has been engaged in the development of this unique technology since the late 1970s, primarily focusing on the development of the Direct Fuel Cell (DFC) technology [1-6] pioneered by ERC. The DFC design incorporates the unique internal reforming feature which allows utilization of a hydrocarbon fuel directly in the fuel cell without requiring any external reforming reactor and associated heat exchange equipment. This approach provides upgrading of waste heat to chemical energy; thereby, it contributing to higher overall efficiency for conversion of fuel energy to electricity with low levels of environmental emissions. Among the internal reforming options, ERC has selected the Indirect Internal Reforming (IIR) - Direct Internal Reforming (DIR) combination as its baseline design. ERC plans to offer commercial DFC power plants in various sizes, initially focusing on the MW-scale units. The plan is to offer standardized, packaged MW-scale DFC power plants operating on natural gas or other hydrocarbon-containing fuels for commercial sale by the end of the decade. These power plants, which can be shop-fabricated and sited near the user, are ideally …

For years, contamination has been known to degrade the performance of optics and to sometimes initiate laser-induced damage to initiate. This study has W to quantify these effects for fused silica windows used at 355 mm Contamination particles (Al, Cu, TiO{sub 2} and ZrO{sub 2}) were artificially deposited onto the surface and damage tests were conducted with a 3 ns NdYAG laser. The damage morphology was characterized by Nomarski optical microscopy. The results showed that the damage morphology for input and output surface contamination is different. For input surface contamination, both input and output surfaces can damage. In particular, the particle can induce pitting or drilling of the surface where the beam exits. Such damage usually grows catastrophically. Output surface contamination is usually ablated away on the shot but can also induce catastrophic damage. Plasmas are observed during illumination and seem to play an important role in the damage mechanism. The relationship between fluence and contamination size for which catastrophic damage occurred was plotted for different contamination materials. The results show that particles even as small as 10 {micro}m can substantially decrease the damage threshold of the window and that metallic particles on the input surface have a more negative …

This paper describes a fiber-optic pH sensor based upon sol-gel encapsulation of a self-referencing dye, seminaphthorhodamine-1 carboxylate (SNARF-1C). The simple sol-gel fabrication procedure and low coating leachability are ideal for encapsulation and immobilization of dye molecules onto the end of an optical fiber. A miniature bench-top fluorimeter system was developed for use with the optical fiber to obtain pH measurements. Linear and reproducible responses were obtained in human blood in the pH range 6.8 to 8.0, which encompasses the clinically-relevant range. Therefore, this sensor can be considered for in vivo use.

We have presented a fast linear time algorithm for recognizing tandem repeats. Our algorithm is a one pass algorithm. No information about the periodicity of tandem repeats is needed. The use of the indices calculated from non-continuous and overlapping {kappa}-tuples allow tandem repeats with insertions and deletions to be recognized.

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This paper introduces PS300, a plasma sprayed, self-lubricating composite coating for use in sliding contacts at temperatures to 800{degrees}C. PS300 is a metal bonded chrome oxide coating with silver and BaF{sub 2}/CaF{sub 2} eutectic solid lubricant additives. PS300 is similar to PS200, a chromium carbide based coating; which is currently being investigated for a variety of tribological applications. In pin-on-disk testing up to 650{degrees}C, PS300 exhibited comparable friction and wear properties to PS200. The PS300 matrix, which is predominantly chromium oxide rather than chromium carbide, does not require diamond grinding and polishes readily with silicon carbide abrasives greatly reducing manufacturing costs compared to PS200. It is anticipated that PS300 has potential for sliding bearing and seal applications in both aerospace and general industry.

Ames Laboratory will develop an integrated sampling and analysis system suitable for on-line monitoring of mercury (Hg) and hydrogen chloride (HCl) in advanced coal-based gasifiers. The objectives of this project are to (1) summarize current technology for monitoring Hg and HCl in gaseous effluents; (2) identify analytical techniques for such determinations in high-temperature, high-pressure gases from coal-based systems for producing electrical power; (3) evaluate promising analytical approaches, and (4) produce reliable on-line monitors which are adaptable to plant-scale diagnostics and process control. For HG, the techniques selected for further consideration were atomic absorption and atomic fluorescence. For HCl, non-dispersive infrared absorption, a dry colorimetric procedure, and ion mobility spectroscopy were selected for testing in the laboratory. Results to date are described.

A general model for predicting the solubility properties of refrigerant/lubricant mixtures has been developed based on applicable theory for the excess Gibbs energy of non-ideal solutions. In our approach, flexible thermodynamic forms are chosen to describe the properties of both the gas and liquid phases of refrigerant/lubricant mixtures. After an extensive study of models for describing non-ideal liquid effects, the Wohl-suffix equations, which have been extensively utilized in the analysis of hydrocarbon mixtures, have been developed into a general form applicable to mixtures where one component is a POE lubricant. In the present study we have analyzed several POEs where structural and thermophysical property data were available. Data were also collected from several sources on the solubility of refrigerant/lubricant binary pairs. We have developed a computer code (NISC), based on the Wohl model, that predicts dew point or bubble point conditions over a wide range of composition and temperature. Our present analysis covers mixtures containing up to three refrigerant molecules and one lubricant. The present code can be used to analyze the properties of R-410a and R-407c in mixtures with a POE lubricant. Comparisons with other models, such as the Wilson or modified Wilson equations, indicate that the Wohl-suffix equations …

A diode-side-pumped discrete-optic E{sup 3+}:YAG laser employs pump-light coupling through a sapphire plate diffusion-bonded to the laser slab, giving reduced thermal lensing and exceptional beam quality (M{sup 2} {approx} 1.3.) The novel architecture is also applicable to other side-pumped lasers.

In this paper we discuss an on-line turbulent load characterization system that has been designed to acquire loading spectra from turbines of the same design operating in several different environments and from different turbine designs operating in the same environment. This System simultaneously measures the rainflow-counted alternating and mean loading spectra and the hub-height turbulent mean shearing stress and atmospheric stability associated with the turbulent inflow. We discuss the theory behind the measurement configuration and the results of proof-of-concept testing recently performed at the National Wind Technology Center (NWTC) using a Bergey EXCEL-S 10-kW wind turbine. The on-line approach to characterizing the load spectra and the inflow turbulent scaling parameter produces results that are consistent with other measurements. The on-line approximation of the turbulent shear stress or friction velocity u* also is considered adequate. The system can be used to characterize turbulence loads during turbine deployment in a wide variety of environments. Using the WISPER protocol, we found that a wide-range, variable-speed turbine will accumulate a larger number of stress cycles in the low-cycle, high-amplitude (LCHA) region when compared with a constant speed rotor under similar inflow conditions.

Designs for advanced integrated gasification combined cycle (IGCC) power systems call for desulfurization of coal gasifier gas at high-temperature, high-pressure (HTHP) conditions using highly efficient, regenerable metal oxides such as zinc titanate. Regeneration of the sulfided sorbent using an oxygen-containing gas stream results in a sulfur dioxide (SO{sub 2})-containing off-gas at HTHP conditions. The patented Direct Sulfur Recovery Process (DSRP) developed by the Research Triangle Institute (RTI) with Morgantown Energy Technology Center (METC) support is an attractive option for treatment of this regeneration off-gas. Using a slipstream of coal gas as a reducing agent, it efficiently converts the SO{sub 2} to elemental sulfur, an essential industrial commodity that is easily stored and transported.

The stability of bcc-based phases in the Ti-Al-Nb alloy system has been studied from first-principles using a combination of ab-initio total energy and cluster variation method (CVM) calculations. Total energies have been computed for 18 binary and ternary bcc superstructures in order to determine low temperature ordering tendencies. From the results of these calculations a set of effective cluster interaction parameters have been derived. These interaction parameters are required input for CVM computations of alloy thermodynamic properties. The CVM has been used to study the effect of composition on finite-temperature ordering tendencies and site preferences for bcc-based phases. Strong ordering tendencies are observed for binary Nb-Al and Ti-Al bcc phases as well as for ternary alloys with compositions near Ti{sub 2}AlNb. For selected superstructures we have also analyzed structural stabilities with respect to tetragonal distortions which transform the bcc into an fcc lattice. Instabilities with respect to such distortions are found to exist for binary but not ternary bcc compounds.

Fuel Cell Engineering Corporation (FCE) is in the fourth year of a DOE Cooperative Agreement Program (private-sector cost-shared) aimed at the demonstration of ERC's direct carbonate fuel cell (DFC) technology at full scale. FCE is a wholly owned subsidiary of Energy Research Corporation (ERC), which has been pursuing the development of the DFC for commercialization near the end of this decade. The DFC produces power directly from hydrocarbon fuels electrochemically, without the need for external reforming or intermediate mechanical conversion steps. As a result, the DFC has the potential to achieve very high efficiency with very low levels of environmental emissions. Modular DFC power plants, which can be shop-fabricated and sited near the user, are ideally suited for distributed generation, cogeneration, industrial, and defense applications. This project is an integral part of the ERC effort to commercialize the technology to serve these applications. Potential users of the commercial DFC power plant under development at ERC will require that the technology be demonstrated at or near the full scale of the commercial products. The objective of the Santa Clara Demonstration Project (SCDP) is to provide the first such demonstration of the technology. The approach ERC has taken in the commercialization of …

We are in the midst of constructing an amplifier laboratory (Arnplab) that will be the physics and engineering proving ground for fill sized segmented glass amplifiers of designs that will outfit the National Ignition Facility (NIF) and Laser Megajoule (LMJ) projects. Amplab will demonstrate the cornerstone mechanical, electrical and optical concepts that support the NW and LMJ amplifier schemes. Here we address the optical diagnostics that will be used to characterize optical performance of the amplifiers. We describe, the apparatus that will be used in pulsed measurements of gain distribution and wave-front distortions. The large aperture diagnostic system or LADS, is now being built through a collaborative effort between CEL-V and LLNL. The LADS will provide measurements of gain and wave front distortions over the fill extracting aperture of the NIF and LMJ prototype amplifiers. The LADS will be able to address each of eight apertures via motorized stages and following semi-automated alignment, take data on the aperture of interest. The LADS should be operational in mid-1997 at LLNL and will be used to characterize the optical performance of the very first fill scale prototype 4 x 2 NIF and LMJ amplifiers. It will be transported to Bordeaux, France to …

The new capacitive deionization system (CDI) removes ions, contaminants impurities from water and other aqueous process streams, and further selectively places the removed ions back into solution during regeneration. It provides a separation process that does not utilize chemical regeneration processes, and thus significantly reduces or completely eliminates secondary wastes associated with the operation of ion exchange resins. In the CDI, electrolyte flows in open channels formed between adjacent electrodes, and consequently the pressure drop is much lower than conventional separation processes. The fluid flow can be gravity fed through these open channels, and does not require membranes. This feature represents a significant advantage over the conventional reverse osmosis systems which include water permeable cellulose acetate membranes, and over the electrodialysis systems which require expensive and exotic ion exchange membranes. The CDI is adaptable for use in a wide variety of commercial applications, including domestic water softening, industrial water softening, waste water purification, sea water desalination, treatment of nuclear and aqueous wastes, treatment of boiler water in nuclear and fossil power plants, production of high-purity water for semiconductor processing, and removal of salt from water for agricultural irrigation. CDI accomplishes this removal of impurities by a variety of mechanisms, but …

Aerogels area class of colloidal materials which have high surface areas and abundant mesoporous structure. SiO{sub 2} aerogels show unique physical, optical and structural properties. When catalytic metals are incorporated in the aerogel framework, the potential exists for new and very effective catalysts for industrial processes. Three applications of these metal-containing SiO{sub 2} aerogels as catalysts are briefly reviewed in this paper--NO{sub x} reduction, volatile organic compound destruction, and partial oxidation of methane.

This paper describes an innovative and unique autonomous vehicle being developed at the Lawrence Livermore National Laboratory (LLNL) for versatile use in hostile environments. Conventional vehicles used in decommissioning and decontaminating, police activity, and unmanned military operations typically are designed with four-wheels or track in contact with the environment. Although four-wheel and track vehicles work well, they are limited in negotiating saturated terrain, steep hills and soft soils. The Spiral Track Autonomous Robot (STAR) is a versatile and maneuverable multi-terrain mobile vehicle that uses the latest available computer technology and two Archimedes screws, in contact with the local environment to intelligently negotiate a hostile environment.

Vortec has successfully completed Phases 1 and 2 of a technology demonstration program for an ''Innovative Fossil Fuel Fired Vitrification Technology for Soil Remediation.'' The principal objective of the program is to demonstrate the ability of a Vortec Cyclone Melting System (CMS) to remediate DOE contaminated soils and other waste forms containing TM RCRA hazardous materials, low levels of radionuclides and TSCA (PCB) containing wastes. The demonstration program will verify the ability of this vitrification process to produce a chemically stable glass final waste form which passes both TCLP and PCT quality control requirements, while meeting all federal and state emission control regulations. The demonstration system is designed to process 36 ton/day of as-received drummed or bulk wastes. The processing capacity equates to approximately 160 barrels/day of waste materials containing 30% moisture at an average weight of 450 lbs./barrel.

We discuss the study of the top quark at future experiments and machines. Top's large mass makes it a unique probe of physics at the natural electroweak scale. We emphasize measurements of the top quark's mass, width, and couplings, as well as searches for rare or nonstandard decays, and discuss the complementary roles played by hadron and lepton colliders.

The MACHO microlensing experiment's time-sampled photometry database contains blue and red lightcurves for nearly 9 million stars in the central bar region of the Large Magellanic Cloud (LMC). We have identified known LMC Planetary Nebulae (PN) in the database and find one, Jacoby 5, to be variable. We additionally present data on the ``parent populations`` of LMC PN, and discuss the star formation history of the LMC bar. 14 refs., 1 fig.