In the United States, economic growth increasingly requires that greater volumes of freshwater be made available for new users, yet supplies of freshwater are already allocated to existing users. Currently, water for new users is made available through re-allocation of xisting water supplies-for example, by cities purchasing agricultural water rights. Water may also be made available through conservation efforts and, in some locales, through the development of ''new'' water from non-traditional sources such as the oceans, deep aquifer rackish groundwater, and water reuse.
Finite-element analyses were performed to simulate the response of a hypothetical masonry shear wall with and without continuous filament ties to various lateral loads. The loads represented three different scenarios: (1) 100 mph wind, (2) explosive attack, and (3) an earthquake. In addition, a static loading analysis and cost comparison were performed to evaluate optimal materials and designs for the spacers affixed to the filaments. Results showed that polypropylene, ABS, and polyethylene (high density) were suitable materials for the spacers based on performance and cost, and the short T-spacer design was optimal based on its performance and functionality. Results of the shear-wall loading simulations revealed that simulated walls with the continuous filament ties yielded factors of safety that were at least ten times greater than those without the ties. In the explosive attack simulation (100 psi), the simulated wall without the ties failed (minimum factor of safety was less than one), but the simulated wall with the ties yielded a minimum factor of safety greater than one. Simulations of the walls subject to lateral loads caused by 100 mph winds (0.2 psi) and seismic events with a peak ground acceleration of 1 ''g'' (0.66 psi) yielded no failures with or without the ties. Simulations of wall displacement during the seismic scenarios showed that the wall with the ties resulted in a maximum displacement that was 20% less than the wall without the ties.
In February of 2005, a joint exercise involving Sandia National Laboratories (SNL) and the National Institute for Occupational Safety and Health (NIOSH) was conducted in Albuquerque, NM. The SNL participants included the team developing the Building Restoration Operations and Optimization Model (BROOM), a software product developed to expedite sampling and data management activities applicable to facility restoration following a biological contamination event. Integrated data-collection, data-management, and visualization software improve the efficiency of cleanup, minimize facility downtime, and provide a transparent basis for reopening. The exercise was held at an SNL facility, the Coronado Club, a now-closed social club for Sandia employees located on Kirtland Air Force Base. Both NIOSH and SNL had specific objectives for the exercise, and all objectives were met.
Polarimetric imaging applications at the 2 to 5 μm or Mid-Wave Infrared (MWIR) range use large pixel-count focal plane arrays (FPA) with small pixel size. This project is centered in designing, fabricating and testing micropolarizers that work in that wavelength regime and intended for that type of FPAs. The micro-polarizers will be used in conjunction with a FPA in snapshot mode and will be in the near field of the imaging device. The pixel pitches for some commercial FPAs are small enough that the finite apertures of the polarizing devices may significantly affect their performance given that their aperture size varies between 3 and 5 waves. We are interested in understanding the effect on extinction ratio due to variations in the edge terminations of a polarizer with a small aperture. Edge terminations are the spaces between the first or last wire with the perimeter of the aperture of the polarizer. While this parameter has negligible effects on a larger polarizer, it will be significant for apertures that are about 3 to 5 waves. We will present data that indicates significant variation in performance due to edge terminations.
Subwavelength diffractive features etched into a substrate lead to form birefringence that can be utilized to produce polarization sensitive elements such as waveplates. Using etched features allows for the development of pixilated devices to be used in conjunction with focal plane arrays in polarimetric imaging systems. Typically, the main drawback from using diffractive devices is their high sensitivity to wavelength. Taking advantage of the dispersion of the form birefringence, diffractive waveplates with good achromatic characteristics can be designed. We will report on diffractive waveplates designed for minimal phase retardation error across the 2-5 micron spectral regime. The required fabrication processes of the sub-wavelength feature sizes will be discussed as well as the achromatic performance and transmission efficiency of final devices. Previous work in this area has produced good results over a subset of this wavelength band, but designing for this extended band is particularly challenging. In addition, the effect of the finite size of the apertures of the pixilated devices is of particular interest since they are designed to be used in conjunction with a detector array. The influence of small aperture sizes will also be investigated.
A split-grating-gate detector design has been implemented in an effort to combine the tunabiliry of the basic gratinggate detector with the high responsivity observed in these detectors when approaching the pinchoff regime. The redesign of the gates by itself offers several orders of magnitude improvement in resonant responsivity. Further improvements are gained by placing the detector element on a thermally isolating membrane in order to increase the effects of lattice heating on the device response.
Hyperspectral imaging provides complex image data with spectral information from many fluorescent species contained within the sample such as the fluorescent labels and cellular or pigment autofluorescence. To maximize the utility of this spectral imaging technique it is necessary to couple hyperspectral imaging with sophisticated multivariate analysis methods to extract meaningful relationships from the overlapped spectra. Many commonly employed multivariate analysis techniques require the identity of the emission spectra of each component to be known or pure component pixels within the image, a condition rarely met in biological samples. Multivariate curve resolution (MCR) has proven extremely useful for analyzing hyperspectral and multispectral images of biological specimens because it can operate with little or no a priori information about the emitting species, making it appropriate for interrogating samples containing autofluorescence and unanticipated contaminating fluorescence. To demonstrate the unique ability of our hyperspectral imaging system coupled with MCR analysis techniques we will analyze hyperspectral images of four-color in-situ hybridized rat brain tissue containing 455 spectral pixels from 550 - 850 nm. Even though there were only four colors imparted onto the tissue in this case, analysis revealed seven fluorescent species, including contributions from cellular autofluorescence and the tissue mounting media. Spectral image analysis will be presented along with a detailed discussion of the origin of the fluorescence and specific illustrations of the adverse effects of ignoring these additional fluorescent species in a traditional microscopy experiment and a hyperspectral imaging system.
Proceedings of SPIE - The International Society for Optical Engineering
Palmer, Jeremy A.; Hsieh, Wen T.; Quijada, Manuel; Mott, Brent; Akpan, Eddie; Brown, Gary L.; Jacobson, Mindy B.; Greenhouse, Matthew A.
A miniature Fabry-Perot tunable infrared filter under development at the NASA Goddard Space Flight Center is fabricated using micro opto electromechanical systems (MOEMS) technology. Intended for wide-field imaging spectroscopy in space flight, it features a large 10-mm diameter aperture structure that consists of a set of opposing suspended thin films 500 nanometers in thickness, supported by annular silicon disks. Achieving the desired effective finesse in the MOEMS instrument requires maximizing the RMS flatness in the film. This paper presents surface characterization data for the suspended aperture film prior to, and following application of a multi-layer dielectric mirror. A maximum RMS flatness of 38 nanometers was measured prior to coating, leading to an estimate of the maximum effective finesse of 14. Results show evidence of initial deformation of the silicon support structure due to internal stress in the substrate and thin film layers. Film stress gradients in the dielectric coating on either side of the aperture add convexity and other localized deflections. The design of a tuning system based upon electrostatic positioning with feedback control is presented.
Optical lime-domain reflectometry (OTDR) is an effeclive technique for locating faults in fiber communication links. The fact that most OTDR measurements are performed manually is a significant drawback, because it makes them too costly for use in many short-distance networks and too slow for use in military avionic platforms. Here we describe and demonstrate an automated, low-cost, real-time approach to fault monitoring that can be achieved by integrating OTDR functionality directly into VCSEL-based transceivers. This built-in test capability is straightforward to implement and relevant to both multimode and single mode networks. In-situ OTDR uses the transmitter VCSEL already present in data transceivers. Fault monitoring is performed by emitting a brief optical pulse into the fiber and then turning the VCSEL off. If a fault exists, a portion of the optical pulse returns to the transceiver after a time equal to the round-trip delay through the fiber. In multimode OTDR, the signal is detected by an integrated photodetector, while in single mode OTDR the VCSEL itself can be used as a detector. Modified driver electronics perform the measurement and analysis. We demonstrate that VCSEL-based OTDR has sufficient sensitivity to determine the location of most faults commonly seen in short-haul networks (i.e., the Fresnel reflections from improperly terminated fibers and scattering from raggedly-broken fibers). Results are described for single mode and multimode experiments, at both 850 nm and 1.3 μm. We discuss the resolution and sensitivity that have been achieved, as well as expected limitations for this novel approach to network monitoring.
We report here on an effort to design and fabricate a polarization splitter that utilizes form-birefringence to disperse an input beam as a function of polarization content as well as wavelength spectrum. Our approach is unique in the polarization beam splitting geometry and the potential for tailoring the polarized beams' phase fronts to correct aberrations or add focusing power. A first cut design could be realized with a chirped duty cycle grating at a single etch depth. However, this approach presents a considerable fabrication obstacle since etch depths are a strong function of feature size, or grating period. We fabricated a period of 1.0 micron form-birefringent component, with a nominal depth of 1.7 microns, in GaAs using a CAIBE system with a 2-inch ion beam source diameter. The gas flows, ion energy, and sample temperature were all optimized to yield the desired etch profile.
Proceedings of SPIE - The International Society for Optical Engineering
Palmer, Jeremy A.; Williams, John D.; Lemp, Tom; Lehecka, Tom M.; Medina, Francisco; Wicker, Ryan B.
This paper describes improvements that enable engineers to create three-dimensional MEMS in a variety of materials. It also provides a means for selectively adding three-dimensional, high aspect ratio features to pre-existing PMMA micro molds for subsequent LIGA processing. This complimentary method involves in situ construction of three-dimensional micro molds in a stand-alone configuration or directly adjacent to features formed by X-ray lithography. Three-dimensional micro molds are created by micro stereolithography (MSL). an additive rapid prototyping technology. Alternatively, three-dimensional features may be added by direct femtosecond laser micro machining. Parameters for optimal femtosecond laser micro machining of PMMA at 800 nanometers are presented. The technical discussion also includes strategies for enhancements in the context of material selection and post-process surface finish. This approach may lead to practical, cost-effective 3-D MEMS with the surface finish and throughput advantages of X-ray lithography. Accurate three-dimensional metal inicrostructures are demonstrated. Challenges remain in process planning for micro stereolithography and development of buried features following femtosecond laser micro machining.
Long-term reliability testing of Micro-Electro-Mechanical Systems (MEMS) is important to the acceptance of these devices for critical and high-impact applications. In order to make predictions on aging mechanisms, these validation experiments must be performed in controlled environments. Additionally, because the aging acceleration factors are not understood, the experiments can last for months. This paper describes the design and implementation of a long-term MEMS reliability test bed for accelerated life testing. The system is comprised of a small environmental chamber mounted on an electrodynamic shaker with a laser Doppler vibrometer (LDV) and digital camera for data collection. The humidity and temperature controlled chamber has capacity for 16 MEMS components in a 4×4 array. The shaker is used to dynamically excite the devices using broadband noise, chirp or any other programmed signal via the control software. Driving amplitudes can be varied to maintain the actuation of the test units at the desired level. The actuation is monitored optically via the LDV which can report the displacement or velocity information of the surface. A springmass accelerated aging experiment was started using a controlled environment of 5000 ppmv humidity (roughly 13% at room temperature), temperature of 29 °C, and ±80μm maximum displacement of the mass. During the first phase of the experiment, the resonant frequency was measured every 2 hours. From 114.5 to 450 hours under stress, measurements were taken every 12 hours and after that every 24 hours. Resonant frequency tracking indicates no changes in the structures for 4200 hours of testing.
A novel dual stage chemiluminescence detection system incorporating individually controlled hot stages has been developed and applied to probe for material interaction effects during polymer degradation. Utilization of this system has resulted in experimental confirmation for the first time that in an oxidizing environment a degrading polymer A (in this case polypropylene, PP) is capable of infecting a different polymer B (in this case polybutadiene, HTPB) over a relatively large distance. In the presence of the infectious degrading polymer A, the thermal degradation of polymer B is observed over a significantly shorter time period. Consistent with infectious volatiles from material A initiating the degradation process in material B it was demonstrated that traces (micrograms) of a thermally sensitive peroxide in the vicinity of PP could induce degradation remotely. This observation documents cross-infectious phenomena between different polymers and has major consequences for polymer interactions, understanding fundamental degradation processes and long-term aging effects under combined material exposures.
This test report covers the SNL modal test results for two nominally identical TX-100 wind turbine blades. The TX-100 blade design is unique in that it features a passive braking, force-shedding mechanism where bending and torsion are coupled to produce desirable aerodynamic characteristics. A specific aim of this test is to characterize the coupling between bending and torsional dynamics. The results of the modal tests and the subsequent analysis characterize the natural frequencies, damping, and mode shapes of the individual blades. The results of this report are expected to be used for model validation--the frequencies and mode shapes from the experimental analysis can be compared with those of a finite-element analysis. Damping values are included in the results of these tests to potentially improve the fidelity of numerical simulations, although numerical finite element models typically have no means of predicting structural damping characteristics. Thereafter, an additional objective of the test is achieved in evaluating the test to test and unit variation in the modal parameters of the two blades.
We have numerically modeled an efficient method of doubling the 1064 nm wavelength of a Q-switched Nd:YAG laser using a lambda-doubling nanosecond optical parametric oscillator (LDOPO). The LDOPO cavity is based on the four-mirror nonplanar RISTRA geometry, denoting rotated-image singly-resonant twisted rectangle, and contains a single type-II KTP crystal. By using the polarization-rotating properties of this cavity, and modifying its geometry to incorporate polarization-selective mirrors with angles of incidence near Brewster's angle, this design obtains stable, singly-resonant oscillation at degeneracy. If the pump laser is injection-seeded, and the LDOPO contains an intra-cavity étalon for single-longitudinal-mode oscillation, the phase of the wavelength-doubled 2128 nm light remains locked to the phase of the pump, independent of cavity length, so active frequency stabilization is not required. Numerical analysis indicates that a pulse-injection-seeded LDOPO can obtain 1064 nm to 2128 nm conversion efficiency exceeding 61%. However, analysis of a complete system incorporating a primary low-energy LDOPO that pulse-injection-seeds a secondary higher-energy LDOPO indicates total 1064 nm to 2128 nm efficiency of approximately 57%. A 2128 nm lambda-doubling system having conversion efficiency > 50% may offer a cost-effective alternative to conventional two micron laser sources such as Tm:Ho:YAG.
We report results from Yb-doped fiber amplifiers seeded with two microchip lasers having 0.38-ns and 2.3-ns pulse durations. The shorter duration seed resulted in output pulses with a peak power of > 1.2 MW and pulse energy of 0.67 mJ. Peak power was limited by nonlinear processes that caused breakup and broadening of the pulse envelope as the pump power increased. The 2.3-ns duration seed laser resulted in output pulses with a peak power of >300 kW and pulse energy of > 1.1 mJ. Pulse energies were limited by the onset of stimulated Brillouin scattering and ultimately by internal optical damage (fluences in excess of 400 J/cm 2 were generated). In both experiments, nearly diffraction-limited beam profiles were obtained, with M 2 values of < 1.2. Preliminary results of a pulse-amplification model are in excellent agreement with the experimental results of the amplifiers operating in the low-to-moderate gain-depletion regime.
As cognitive systems technologies emerge, so too do the ethical issues surrounding their development and use. To develop cognitive systems technologies responsibly, Sandia National Laboratories is establishing a framework to proactively address both real and potential ethical issues. This report contains the principles and guidelines developers can use to guide them as they are confronted with ethical issues related to developing cognitive systems technologies as they apply to U.S. national security. A process to apply these principles offers a practical way to transfer these principles from paper to a working strategy. Case studies are presented to reflect upon potential scenarios and to consider resolution strategies.
From 1994 through 2005, the Environmental Management Department of Sandia National Laboratories (SNL) at the Tonopah Test Range (TTR), NV, has collected soil samples at numerous locations on-site, on the perimeter, and off-site for the purpose of determining potential impacts to the environs from operations at TTR. These samples were submitted to an analytical laboratory of metal-in-soil analyses. Intercomparisons of these results were then made to determine if there was any statistical difference between on-site, perimeter, and off-site samples, or if there were increasing or decreasing trends which indicated that further investigation may be warranted. This work provided the SNL Environmental Management Department with a sound baseline data reference against which to compare future operational impacts. In addition, it demonstrates the commitment that the Laboratories have to go beyond mere compliance to achieve excellence in its operations. This data is presented in graphical format with narrative commentaries on particular items of interest.
In this report, we characterize the key themes of transformation and tie them together in a ''how to'' guide. The perspectives were synthesized from strategic management literature, case studies, and from interviews with key management personnel from private industry on their transformation experiences.
Structured adaptive mesh refinement methods are being widely used for computer simulations of various physical phenomena. Parallel implementations potentially offer realistic simulations of complex three-dimensional applications. But achieving good scalability for large-scale applications is non-trivial. Performance is limited by the partitioner's ability to efficiently use the underlying parallel computer's resources. Designed on sound SAMR principles, Nature+Fable is a hybrid, dedicated SAMR partitioning tool that brings together the advantages of both domain-based and patch-based techniques while avoiding their drawbacks. But the original bi-level partitioning approach in Nature+Fable is insufficient as it for realistic applications regards frequently occurring bi-levels as ''impossible'' and fails. This document describes an improved bi-level partitioning algorithm that successfully copes with all possible bi-levels. The improved algorithm uses the original approach side-by-side with a new, complementing approach. By using a new, customized classification method, the improved algorithm switches automatically between the two approaches. This document describes the algorithms, discusses implementation issues, and presents experimental results. The improved version of Nature+Fable was found to be able to handle realistic applications and also to generate less imbalances, similar box count, but more communication as compared to the native, domain-based partitioner in the SAMR framework AMROC.
Military test and training ranges operate with live-fire engagements to provide realism important to the maintenance of key tactical skills. Ordnance detonations during these operations typically produce minute residues of parent explosive chemical compounds. Occasional low-order detonations also disperse solid-phase energetic material onto the surface soil. These detonation remnants are implicated in chemical contamination impacts to groundwater on a limited set of ranges where environmental characterization projects have occurred. Key questions arise regarding how these residues and the environmental conditions (e.g., weather and geostratigraphy) contribute to groundwater pollution. This final report documents the results of experimental and simulation model development for evaluating mass transfer processes from solid-phase energetics to soil-pore water.
This research focuses on the development of a constitutive model for carbon nanotube polymer composites incorporating nanoscale attributes of the interface between the nanotube and polymer. Carbon nanotube polymer composites exhibit promising properties, as structural materials and the current work will motivate improvement in their load transfer capabilities. Since separation events occur at different length and time scales, the current work also addresses the challenge of multiscale modeling in interpreting inputs at different length and time scales. The nanoscale phase separation phenomena are investigated using molecular dynamics (MD) simulations. The simulations based on MD provide grounds for developing a cohesive zone model for the interface based on laws of thermodynamics.
Exergy is the elixir of life. Exergy is that portion of energy available to do work. Elixir is defined as a substance held capable of prolonging life indefinitely, which implies sustainability of life. In terms of mathematics and engineering, exergy sustainability is defined as the continuous compensation of irreversible entropy production in an open system with an impedance and capacity-matched persistent exergy source. Irreversible and nonequilibrium thermodynamic concepts are combined with self-organizing systems theories as well as nonlinear control and stability analyses to explain this definition. In particular, this paper provides a missing link in the analysis of self-organizing systems: a tie between irreversible thermodynamics and Hamiltonian systems. As a result of this work, the concept of ''on the edge of chaos'' is formulated as a set of necessary and sufficient conditions for stability and performance of sustainable systems. This interplay between exergy rate and irreversible entropy production rate can be described as Yin and Yang control: the dialectic synthesis of opposing power flows. In addition, exergy is shown to be a fundamental driver and necessary input for sustainable systems, since exergy input in the form of power is a single point of failure for self-organizing, adaptable systems.
We present the use of micron-sized lipid domains, patterned onto planar substrates and within microfluidic channels, to assay the binding of bacterial toxins via total internal reflection fluorescence microscopy (TIRFM). The lipid domains were patterned using a polymer lift-off technique and consisted of ganglioside-populated DSPC:cholesterol supported lipid bilayers (SLBs). Lipid patterns were formed on the substrates by vesicle fusion followed by polymer lift-off, which revealed micron-sized SLBs containing either ganglioside GT1b or GM1. The ganglioside-populated SLB arrays were then exposed to either Cholera toxin subunit B (CTB) or Tetanus toxin fragment C (TTC). Binding was assayed on planar substrates by TIRFM down to 1 nM concentration for CTB and 100 nM for TTC. Apparent binding constants extracted from three different models applied to the binding curves suggest that binding of a protein to a lipid-based receptor is strongly affected by the lipid composition of the SLB and by the substrate on which the bilayer is formed. Patterning of SLBs inside microfluidic channels also allowed the preparation of lipid domains with different compositions on a single device. Arrays within microfluidic channels were used to achieve segregation and selective binding from a binary mixture of the toxin fragments in one device. The binding and segregation within the microfluidic channels was assayed with epifluorescence as proof of concept. We propose that the method used for patterning the lipid microarrays on planar substrates and within microfluidic channels can be easily adapted to proteins or nucleic acids and can be used for biosensor applications and cell stimulation assays under different flow conditions. KEYWORDS. Microarray, ganglioside, polymer lift-off, cholera toxin, tetanus toxin, TIRFM, binding constant.4
The Radiation Effects Sciences (RES) program is responsible for conducting Neutron Gamma Energy Transport (NuGET) code validation. In support of this task, a series of experiments were conducted in the annular core research reactor (ACRR) to investigate the modification of the incident neutron/gamma environment by aluminum (Al6061) and high-density polyethylene (HDPE) spheres with 4-in and 7-in-diameter. The experiment series described in this report addresses several NuGET validation concerns. The validation experiment series also addresses the design and execution of proper reactor testing to match the hostile radiation environments and to match the component stresses that arise from the hostile radiation environments. This report summarizes the RES Validation: n/{gamma} Attenuation through Materials, Environments 1A, experiments conducted at the ACRR in FY 2003 using ACRR Experiment Plans 933 and 949.
HVIS 2005 was a clear success. The Symposium brought together nearly two hundred active researchers and students from thirteen countries around the world. The 84 papers presented at HVIS 2005 constitute an ''update'' on current research and the state-of-the-art of hypervelocity science. Combined with the over 7000 pages of technical papers from the eight previous Symposia, beginning in 1986, all published in the International Journal of Impact Engineering, the papers from HVIS 2005 add to the growing body of knowledge and the progressing state-of-the-art of hypervelocity science. It is encouraging to report that even with the limited funding resources compared to two decades ago, creativity and ingenuity in hypervelocity science are alive and well. There is considerable overlap in different disciplines that allows researchers to leverage. Experimentally, higher velocities are now available in the laboratory and are ideally suited for space applications that can be tied to both civilian (NASA) and DoD military applications. Computationally, there is considerable advancement both in computer and modeling technologies. Higher computing speeds and techniques such as parallel processing allow system level type applications to be addressed directly today, much in contrast to the situation only a few years ago. Needless to say, both experimentally and computationally, the ultimate utility will depend on the curiosity and the probing questions that will be incumbent upon the individual researcher. It is quite satisfying that over two dozen students attended the symposium. Hopefully this is indicative of a good pool of future researchers that will be needed both in the government and civilian industries. It is also gratifying to note that novel thrust areas exploring different and new material phenomenology relevant to hypervelocity impact, but a number of other applications as well, are being pursued. In conclusion, considerable progress is still being made that is beneficial for continuous development of hypervelocity impact technology and applications even with the relatively limited resources that are being directed in this field.