Models for the nonlinear instability of finite thickness shells driven by pressure are constructed in the style of Layzer. Equations for both Cartesian and cylindrically convergent/divergent geometries are derived. The resulting equations are appropriate for incompressible shells with unity Atwood number. Predictions from the equations compare well with two-dimensional simulations.

To assist the University of California in obtaining biological assessment information for the ''2004 Environmental Impact Statement for Continued Operation of Lawrence Livermore National Laboratory (LLNL)'', Jones & Stokes conducted an inventory of small mammals in six major vegetation communities at Site 300. These communities were annual grassland, native grassland, oak savanna, riparian corridor, coastal scrub, and seep/spring wetlands. The principal objective of this study was to assess the diversity and abundance of small mammal species in these communities, as well as the current status of any special-status small mammal species found in these communities. Surveys in the native grassland community were conducted before and after a controlled fire management burn of the grasslands to qualitatively evaluate any potential effects of fire on small mammals in the area.

Using molecular dynamics simulations, we have studied the deformation of polysynthetically twinned (PST) TiAl at room temperature with a bicrystal model. The simulation cell was pre-strained and thermodynamically relaxed to a criterion that all stress components of the simulation cell have gone to zeros; in this way no dislocations were pre-existed in {gamma}-{alpha}{sub 2} interfaces. A uniaxial compression was then applied along one 1/6<112] direction in the surface. The results show that under the compression, the interfacial dislocation pairs were prolifically generated due to the structural transformation of {alpha}{sub 2}-lamella. The gliding and agglomerating of these dislocations would finally cause the nucleation of deformation twins from the interface. This is suggested to be a new possible twinning mechanism in the dual phase TiAl alloy. The propagation of this deformation twin, or specifically, its interaction with {gamma}-{gamma} and {gamma}-{alpha}{sub 2} interfaces has been discussed. It shows that the {alpha}{sub 2}-lamella is intent to block the propagation of the deformation twin.

The overall objective of this study was to develop probabilistic seismic hazard estimates for the coastal and offshore area of Ventura, Los Angeles and Orange counties for use as a basis for the University of Southern California (USC) to develop physical models of tsunami for the coastal regions and by the California State Lands Commission (SLC) to develop regulatory standards for seismic loading and liquefaction evaluation of marine oil terminals. The probabilistic seismic hazard analysis (PSHA) was carried out by the Lawrence Livermore National Laboratory (LLNL), in several phases over a time period of two years, following the method developed by LLNL for the estimation of seismic hazards at Department Of Energy (DOE) facilities, and for 69 locations of nuclear plants in the Eastern United States, for the Nuclear Regulatory Commission (NRC). This method consists in making maximum use of all physical data (qualitative, and quantitative) and to characterize the uncertainties by using a set of alternate spatiotemporal models of occurrence of future earthquakes, as described in the SSHAC, PSHA Guidance Document (Budnitz et al., 1997), and implemented for the NRC (Savy et al., 2002). In general, estimation of seismic hazard is based not only on our understanding of the …

Methods and results for calculations of the ground state energy of the bulk system of {sup 3}He atoms are discussed. Results are encouraging: they believe that they demonstrate that their methods offer a solution of the ''fermion sign problem'' and the possibility of direct computation of many-fermion systems with no uncontrolled approximations. Nevertheless, the method is still rather inefficient compared with variational or fixed-node approximate methods. There appears to be a significant populations size effect. The situation is improved by the inclusion of ''Second Stage Importance Sampling'' and of ''Acceptance/Rejection'' adapted to their needs.

Reliable quantitative prediction of contaminant transport in subsurface environments is critical to evaluating the risks associated with radionuclide migration. As part of the Underground Test Area (UGTA) program, radionuclide transport away from selected underground nuclear tests conducted in the saturated zone at the Nevada Test Site (NTS) is being examined. In the near-field environment, reactive transport simulations must account for changes in water chemistry and mineralogy as a function of time and their effect on radionuclide migration. Unlike the Kd approach, surface complexation reactions, in conjunction with ion exchange and precipitation, can be used to describe radionuclide reactive transport as a function of changing environmental conditions. They provide a more robust basis for describing radionuclide retardation in geochemically dynamic environments. In a companion report (Zavarin and Bruton, 2004), a database of radionuclide surface complexation reactions for calcite and iron oxide minerals was developed. In this report, a second set of reactions is developed: surface complexation (SC) and ion exchange (IE) to aluminosilicate minerals. The most simplified surface complexation model, the one-site non-electrostatic model (NEM), and the Vanselow IE model were used to fit a large number of published sorption data and a reaction constant database was developed. Surface complexation of …

Condor Country Consulting conducted surveys for listed branchiopods in the 2002-2003 wet season to complete requirements of the Guidelines (USFWS 1996) used to determine the distribution of federally-listed branchiopods within the study area. The first survey was performed during the previous wet season (2001-2002). The 2002-2003 wet season survey, combined with the previous season's survey, is intended to provide LLNL with information that will assist them in determining the effects of the proposed action on federally listed branchiopods and provide information useful in the preparation of the associated environmental documentation. It is also expected to satisfy the survey requirements of the USFWS. For the purpose of this report, the term branchiopod refers specifically to phyllopodous branchiopods and not cladocerans. Fairy shrimp, tadpole shrimp, and clam shrimp are all categorized as phyllopodous branchiopods and are currently the only members of the Class Branchiopoda that contain species that are listed under the federal Endangered Species Act. Although cladocerans are branchiopods and were found on the site, they are only referred to by the Order in this report because they are not the target species of this study.

Two methods of up-scaling coupled equations at the microscale to equations valid at the mesoscale and/or macroscale for fluid-saturated and partially saturated porous media are discussed, compared, and contrasted. The two methods are: (1) two-scale and multiscale homogenization, and (2) volume averaging. Both these methods have advantages for some applications and disadvantages for others. For example, homogenization methods can give formulas for coefficients in the up-scaled equations, whereas volume averaging methods give the form of the up-scaled equations but generally must be supplemented with physical arguments and/or data in order to determine the coefficients. Homogenization theory requires a great deal of mathematical insight from the user in order to choose appropriate scalings for use in the resulting power-law expansions, while volume averaging requires more physical insight to motivate the steps needed to find coefficients. Homogenization often is performed on periodic models, while volume averaging does not require any assumption of periodicity and can therefore be related very directly to laboratory and/or field measurements. Validity of the homogenization process is often limited to specific ranges of frequency - in order to justify the scaling hypotheses that must be made - and therefore cannot be used easily over wide ranges of frequency. …

This goal of this project was to perform feasibility experiments and measurements of the fundamental interactions between hydrogen and single wall carbon nanotubes (SWNT) at high pressures. High-pressure is an adjustable experimental parameter for tuning interaction strengths, thereby elucidating and providing insights into the fundamental nature of the H{sub 2}/SWNT system. We have developed and utilized systems and methodologies to make x-ray scattering, optical spectroscopic and electrical transport measurements. These activities have been productive in demonstrating capabilities and measuring properties of SWNTs under high-pressure conditions. We have also developed strong cooperative and complementary relationships with academic research colleagues at Stanford University. Building on these results and relationships, we hope to continue and expand our research as co-investigators in a joint Harvard-LLNL-Stanford proposal to the DOE ''Grand Challenge'' for Basic and Applied Research in Hydrogen Storage (Solicitation No. DE-PS36-03GO93013). Hydrogen storage is an active research topic with important basic science implications and a crucial enabling technology for advanced energy systems. Measurements of the H{sub 2} storage capacity indicate that it may achieve or exceed the storage capacity level (6.5 wt-%) mandated by the DOE hydrogen plan for fielding a hydrogen-fueled vehicle. The H{sub 2}/SWNT system has been the subject of intensive …

The microstructural evolution of high purity steel under irradiation is modeled including a dislocation density that evolves simultaneously with void nucleation and growth. The predicted void swelling trends versus temperature, flux, and time are compared to experiment and to earlier calculations with a fixed dislocation density. The behavior is further analyzed within a simplified picture of segregation of irradiation defects to microstructural sinks. Agreement with experimental swelling behavior improves when dislocations co-evolve with the void content versus simulations with a fixed dislocation density. The time-dependent dislocation content dictates the rate of void nucleation and shapes the overall void size distribution so as to give steady swelling behavior over long times.

There are many accelerator applications for high intensity heavy ion sources, with recent needs including dc beams for RIA, and pulsed beams for injection into synchrotrons such as RHIC and LHC. The present status of sources producing high currents of high charge state heavy ions is reviewed. These sources include ECR, EBIS, and Laser ion sources. Benefits and limitations for these type sources are described. Possible future improvements in these sources are also mentioned.

The field of x-ray optics struggles to develop optical systems with the versatility and sophistication of their visible light counterparts. The advent of fourth-generation light sources will make the struggle even more difficult. Fourth-generation light sources include laser/plasma sources, x-ray Free Electron Lasers (FEL), inverse Compton scattering sources, and the National Ignition Facility. LCLS, (Linac Coherent Light Source), and its European cousin, will be the first of the x-ray FELs. The LCLS, to be built at the Stanford Linear Accelerator Center (SLAC), takes advantage of the existing SLAC linear accelerator to send intense, low emittance electron bunches through a 100 m long undulator structure. Through a process called SASE (Self Amplification of Spontaneous Emission) the electrons interact with the radiation fields they produce while in the undulator causing them to collect into micro bunches that emit coherent light. In the case of the LCLS the coherent radiation will have a wavelength in the x-ray regime, and will be tunable from 1.5 to 15 {angstrom}. The LCLS will deliver x-rays in individual coherent packages lasting < 300 fs, making the LCLS a very important source for studying short time phenomenon and for performing high-resolution x-ray structural analysis of molecular sized systems. …

Lawrence Livermore National Laboratory (LLNL), operated under cooperative agreement between the University of California and the U. S. Department of Energy, administers and operates an approximately 11 mi{sup 2} (28 km{sup 2}) test site in the remote hills at the northern end of the South Coast Ranges of Central California (Figure 1). Known as Site 300, this expanse of rolling hills and canyons supports a diverse array of grassland communities typical of lowland central California. The facility serves a variety of functions related to testing non-nuclear explosives, lasers, and weapons subsystems. The primary purpose of this project was to determine the presence of any mesocarnivores on Site 300 that use the property for foraging, denning, and other related activities. The surveys occurred from mid-September to mid-October, 2002.

We present a progressive compression technique for volumetric subdivision meshes based on the slow growing refinement algorithm. The system is comprised of a wavelet transform followed by a progressive encoding of the resulting wavelet coefficients. We compare the efficiency of two wavelet transforms. The first transform is based on the smoothing rules used in the slow growing subdivision technique. The second transform is a generalization of lifted linear B-spline wavelets to the same multi-tier refinement structure. Direct coupling with a hierarchical coder produces progressive bit streams. Rate distortion metrics are evaluated for both wavelet transforms. We tested the practical performance of the scheme on synthetic data as well as data from laser indirect-drive fusion simulations with multiple fields per vertex. Both wavelet transforms result in high quality trade off curves and produce qualitatively good coarse representations.

Multiresolution methods are a common technique used for dealing with large-scale data and representing it at multiple levels of detail. The authors present a multiresolution hierarchy construction based on n{radical}2 subdivision, which has all the advantages of a regular data organization scheme while reducing the drawback of coarse granularity. The n{radical}2-subdivision scheme only doubles the number of vertices in each subdivision step regardless of dimension n. They describe the construction of 2D, 3D, and 4D hierarchies representing surfaces, volume data, and time-varying volume data, respectively. The 4D approach supports spatial and temporal scalability. For high-quality data approximation on each level of detail, they use downsampling filters based on n-variate B-spline wavelets. They present a B-spline wavelet lifting scheme for n{radical}2-subdivision steps to obtain small or narrow filters. Narrow filters support adaptive refinement and out-of-core data exploration techniques.

Despite the rapid combustion typically experienced in Homogeneous Charge Compression Ignition (HCCI), components in fuel mixtures do not ignite in unison or burn equally. In our experiments and modeling of blends of diethyl ether (DEE) and ethanol (EtOH), the DEE led combustion and proceeded further toward completion, as indicated by {sup 14}C isotope tracing. A numerical model of HCCI combustion of DEE and EtOH mixtures supports the isotopic findings. Although both approaches lacked information on incompletely combusted intermediates plentiful in HCCI emissions, the numerical model and {sup 14}C tracing data agreed within the limitations of the single zone model. Despite the fact that DEE is more reactive than EtOH in HCCI engines, they are sufficiently similar that we did not observe a large elongation of energy release or significant reduction in inlet temperature required for light-off, both desired effects for the combustion event. This finding suggests that, in general, HCCI combustion of fuel blends may have preferential combustion of some of the blend components.

An issue of the axial electron heat loss is of a significant importance for mirror-based fusion devices. This problem has been considered in a number of publications but it is still shrouded in misconceptions. In this paper we revisit it once again. We discuss the following issues: (1) Formation of the electron distribution function in the end tank at large expansion ratios; (2) The secondary emission from the end plates and the ways of suppressing it (if needed); (3) Ionization and charge exchange in the presence of neutrals in the end tanks; (4) Instabilities caused by the peculiar shape of the electron distribution function and their possible impact on the electron heat losses; (5) Electron heat losses in the pulsed mode of operation of mirror devices.

A compendium of LLNL Science and Technology Review articles involving scientist and engineers from the Physics and Advanced Technologies Directorate, from January 2002 to the present.

The Peak Detector/Derandomizer ASIC (PDD) provides threshold discrimination, peak detection, time-to-amplitude conversion, analog memory, sparsification, and multiplexing for 32 channels of analog pulse data. In this work the spectroscopic capabilities of the chip (high resolution and high rate) are demonstrated along with correlated measurements of pulse risetime. Imaging and coincidence detection using the PDD chip will also be illustrated.

The use of isoconversional, sometimes called model-free, kinetic analysis methods have recently gained favor in the thermal analysis community. Although these methods are very useful and instructive, the conclusion by some that model fitting is a poor approach is largely due to improper use of model fitting, such as fitting a single heating rate or multiple heating rates separately. The current paper shows the ability of model fitting to correlate reaction data over very wide time-temperature regimes for three polymers of interest for formulating high explosives: Estane 5703 P (poly [ester urethane] block copolymer), Viton A (vinylidene-hexafluoropropene copolymer), and Kel-F 800 (vinylidene-chlorotrifluorethene copolymer). The Kel-F required two parallel reactions--one describing an early decomposition process accounting for {approx}1% weight loss and a second autocatalytic reaction describing the remainder of pyrolysis. Essentially no residue was obtained. Viton A and Estane also required two parallel reactions for primary pyrolysis. For Viton A, the first reaction is also a minor, early process, but for Estane, it accounts for 42% of the mass loss. In addition, these to polymers yield 2-3% of residue, and the amount depends on the heating rate. This is an example of a competitive reaction between volatilization and char formation, which …

We developed the Piecewise-Linear Haar (PLHaar) transform, an integer wavelet-like transform. PLHaar does not have dynamic range expansion, i.e. it is an n-bit to n-bit transform. To our knowledge PLHaar is the only reversible n-bit to n-bit transform that is suitable for lossy and lossless coding. We are investigating PLHaar's use in lossy image coding. Preliminary results from thresholding transform coefficients show that PLHaar does not produce objectionable artifacts like prior n-bit to n-bit transforms, such as the transform of Chao et al. (CFH). Also, at lower bitrates PLHaar images have increased contrast. For a given set of CFH and PLHaar coefficients with equal entropy, the PLHaar reconstruction is more appealing, although the PSNR may be lower.

The problem of robust automatic road detection in remotely sensed images is complicated by the fact that the sensor, spatial resolution, acquisition conditions, road width, road orientation and road material composition can all vary. A novel technique for detecting road pixels in multi-source remotely sensed images based on the phase (i.e., orientation or directional) information in edge pixels is described. A very dense map of edges extracted from the image is separated into channels, each containing edge pixels whose phases lie within a different range of orientations. The edge map associated with each channel is de-cluttered. A map of road pixels is formed by re-combining the de-cluttered channels into a composite edge image which is itself then separately de-cluttered. Road detection results are provided for DigitalGlobe and TerraServerUSA images. Road representations suitable for various applications are then discussed.

Networks have recently emerged as a unifying theme in complex systems research [1]. It is in fact no coincidence that networks and complexity are so heavily intertwined. Any future definition of a complex system should reflect the fact that such systems consist of many mutually interacting components. These components are far from being identical as say electrons in systems studied by condensed matter physics. In a truly complex system each of them has a unique identity allowing one to separate it from the others. The very first question one may ask about such a system is which other components a given component interacts with? This information system wide can be visualized as a graph, whose nodes correspond to individual components of the complex system in question and edges to their mutual interactions. Such a network can be thought of as a backbone of the complex system. Of course, system's dynamics depends not only on the topology of an underlying network but also on the exact form of interaction of components with each other, which can be very different in various complex systems. However, the underlying network may contain clues about the basic design principles and/or evolutionary history of the complex …

The problem of imaging of targets in random media or cluttered environments is found in a wide variety of different applications, including ocean acoustics, medical ultrasound, geophysics, and radar. The solution often requires separating targets of interest from other scatterers, and compensating for wave speed variations in the medium. The problem is not usually the lack of data, but too much data, specifically the lack of a useful organizing principle for the data. The difficult part is separating the meaningful data from the remainder. It would therefore be most helpful if there were some means for skipping over those parts of the data that we do not really want to image very much, and looking at those parts (targets) that do interest us. This sounds challenging (maybe even impossible), but recent developments in acoustics make it clear that certain very limited imaging goals are achievable with much smaller data sets than are traditionally needed in, for example, seismic array processing. Early versions of this new method have been given the names of ''time-reversal acoustics'' or ''time-reversal mirrors,'' and have been developed most extensively by the French ultrasonics group led by Fink.