A review of the applicability of Pitzer's equations to the aqueous thermodynamics of actinide species in natural waters is presented. This review includes a brief historical perspective on the application of Pitzer's equations to actinides, information on the difficulties and complexities of studying and modeling the different actinide oxidation states, and a discussion of the use of chemical analogs for different actinide oxidation states. included are tables of Pitzer ion-interaction parameters and associated standard state equilibrium constants for each actinide oxidation state. These data allow the modeling of the aqueous thermodynamics of different actinide oxidation states to high ionic strength.

An algorithm known as SMAC (Synthesize Modes And Correlate), based on principles of modal filtering, has been in development for a few years. The new capabilities of the automated version are demonstrated on test data from a complex shell/payload system. Examples of extractions from impact and shaker data are shown. The automated algorithm extracts 30 to 50 modes in the bandwidth from each column of the frequency response function matrix. Examples of the synthesized Mode Indicator Functions (MIFs) compared with the actual MIFs show the accuracy of the technique. A data set for one input and 170 accelerometer outputs can typically be reduced in an hour. Application to a test with some complex modes is also demonstrated.

Silicon crystal monochromators at cryogenic temperatures have been used with great success at third-generation synchrotrons radiation sources. At the Advanced Photon Source (APS) the unique characteristics of silicon at liquid nitrogen temperatures (77 K) have been leveraged to significantly reduce the thermally induced distortions on beamline optical components. Finite element simulations of the nonlinear (temperature-dependent material properties) thermal stress problem were performed and compared with the experimental measurements. Several critical finite element modeling considerations are discussed for their role in accurately predicting the highly coupled thermal and structural response of the optical component's surface distortion to the high thermal heat flux. Depending on the estimated convection heat transfer coefficient, the final refined finite element model's predictions correlated well with the experimental measurements.

Inductive energy storage systems can have high energy density, lending to smaller, less expensive systems. The crucial element of an inductive energy storage system is the opening switch. This switch must conduct current while energy is stored in an inductor, then open quickly to transfer this energy to a load. Plasma can perform this function. The Plasma Opening Switch (POS) has been studied for more than two decades. Success with the conventional plasma opening switch has been limited. A system designed to significantly improve the performance of vacuum opening switches is described in this paper. The gap cleared of plasma is a rough figure-of-merit for vacuum opening switches. Typical opened gaps of 3 mm are reported for conventional switches. The goal for the system described in this paper is more than 3 cm. To achieve this, the command-triggered POS adds an active opening mechanism, which allows complete separation of conduction and opening. This separation is advantageous because of the widely different time scales of conduction and opening. The detrimental process of magnetic field penetration into the plasma during conduction is less important in this switch. The opening mechanism duration is much shorter than the conduction time, so penetration during opening …

Laser-plasma interactions are sensitive to both the fine-scale speckle and the larger scale envelope intensity of the beam. For some time, simulations have been done on volumes taken from part of the laser beam cross-section, and the results from multiple simulations extrapolated to predict the behavior of the entire beam. However, extrapolation could very well miss effects of the larger scale structure on the fine-scale. The only definitive method is to simulate the entire beam. These very large calculations have been infeasible until recently, but they are now possible on massively parallel computers. Whole beam simulations show the dramatic difference in the propagation and break up of smoothed and aberrated beams.

A new high-speed x-ray beam chopper using laser scanner technology has been developed and tested on the SRI-CAT sector 1 beamline at the Advanced Photon Source (APS) storage ring (1). As illustrated in figure 1, it is compact in size and has two sets of transmission windows: BK-7 glass for visible light transmission and 0.23-mm-thick Be for the transmission of x-rays. The rotor is made of aluminum and has a diameter of 50.8 mm. A 0.5-mm-wide and 2.29-mm-tall slit is cut through the center of the rotor. The circumference of the rotor has a coating of 1-mm-thick Ni, which gives an attenuation of 10{sup 8} at 30 keV. Turning at nearly 80000 RPM, this beam chopper has an opening time window of 2450 ns, corresponding to 67% of the revolution time of the APS storage ring. The primary feature in selecting laser scanner technology to develop into an x-ray beam chopper was the high level of rotational speed control of the rotor that makes up the beam chopper element (2). By using an optical feedback circuit to sample the rotational speed four times each revolution, the jitter in the position of the transmission open time window is only 3 ns …

In the past decade, several third-generation synchrotrons x-ray sources have been constructed and commissioned around the world. Many of the major problems in the development and design of the optical components capable of handling the extremely high heat loads of the generated x-ray beams have been resolved. It is expected, however, that in the next few years even more powerful x-ray beams will be produced at these facilities, for example, by increasing the particle beam current. In this paper, the design of a next generation of synchrotron x-ray mirrors is discussed. The author shows that the design of contact-cooled mirrors capable of handing x-ray beam heat fluxes in excess of 500 W/mm{sup 2} - or more than three times the present level - is well within reach, and the limiting factor is the thermal stress rather then thermally induced slope error.

The goal of this study was to develop a three-dimensional imaging method for studies of deformation in low-density materials during loading, and to implement finite element solutions of the elastic equations based on the images. Specimens of silica-reinforced polysiloxane foam pads, 15 mm in diameter by 1 mm thick, were used for this study. The nominal pore density was 50%, and the pores approximated interconnected spheres. The specimens were imaged with microtomography at {approx}16{micro}m resolution. A rotating stage with micrometer driven compression allowed imaging of the foams during deformation with precise registration of the images. A finite element mesh, generated from the image voxels, was used to calculate the mechanical properties of the structure, and the results were compared with conventional mechanical testing. The foam exhibited significant nonlinear behavior with compressive loading. The finite-element calculations from the images, which were in excellent agreement with experimental data, suggested that nonlinear behavior in the load displacement curves arises from buckling of the cell walls during compression and not from any nonlinear properties of the base elastomer. High-resolution microtomography, coupled with efficient finite-element modeling, shows promise for improving our understanding of the deformation behavior of cellular materials.

An experimental setup to perform high-resolution time-resolved X-ray scattering has been commissioned on the side station of beamline 8-ID at the Advanced Photon Source. A Peltier-cooled diode detector array covering an angle range of 20 degrees is mounted on a 4-circle goniometer and is used to temporally resolve X-ray scattering patterns with a resolution up to 10 ms. Metallic ribbon samples can be quickly heated and cooled from temperatures up to 500 C inside a furnace with controllable atmosphere and equipped with a beryllium window. A description of the setup is presented along with actual results showing time-resolved phase transitions and crystallization processes in AlYNi metallic alloys. These results demonstrate the power of this technique to investigate complex crystallization processes as well as the versatility of this time-resolved X-ray scattering spectrometer.

The collisions of ultra-relativistic nuclei provide a window on the behavior of strong interactions at asymptotically high energies. They also will allow the authors to study the bulk properties of hadronic matter at very high densities.