Sample records for radar absorbing materials

  1. The design of broadband radar absorbing surfaces

    NASA Astrophysics Data System (ADS)

    Suk, Go H.

    1990-09-01

    There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order to escape detection while a covert mission is being carried on. These requirements have led to the very low observable or stealth technology that reduces the probability of detection of an aircraft. The design of radar absorbing materials is limited by constraints on the allowable volume and weight of the surface coating, and it is difficult to design a broadband radar absorbing structure in limited volume. This thesis investigates the use of lossy dielectric materials of high dielectric permittivity in multilayer composites for the production of low radar cross section (RCS). The analysis is done by computing the plane wave reflection coefficient at the exterior surface of the composite coating by means of a computer program which selects layer parameters which determine low reflection coefficients for electromagnetic radiation under constraint of limited layer thickness as well as maximum frequency bandwidth.

  2. A Novel, Real-Valued Genetic Algorithm for Optimizing Radar Absorbing Materials

    NASA Technical Reports Server (NTRS)

    Hall, John Michael

    2004-01-01

    A novel, real-valued Genetic Algorithm (GA) was designed and implemented to minimize the reflectivity and/or transmissivity of an arbitrary number of homogeneous, lossy dielectric or magnetic layers of arbitrary thickness positioned at either the center of an infinitely long rectangular waveguide, or adjacent to the perfectly conducting backplate of a semi-infinite, shorted-out rectangular waveguide. Evolutionary processes extract the optimal physioelectric constants falling within specified constraints which minimize reflection and/or transmission over the frequency band of interest. This GA extracted the unphysical dielectric and magnetic constants of three layers of fictitious material placed adjacent to the conducting backplate of a shorted-out waveguide such that the reflectivity of the configuration was 55 dB or less over the entire X-band. Examples of the optimization of realistic multi-layer absorbers are also presented. Although typical Genetic Algorithms require populations of many thousands in order to function properly and obtain correct results, verified correct results were obtained for all test cases using this GA with a population of only four.

  3. Fabrication of Radar Absorbing Shells Made of Hybrid Composites and Evaluation of Radar Cross Section

    Microsoft Academic Search

    Woo-Kyun Jung; Sung-Hoon Ahn; Bierng-Chearl Ahn

    2005-01-01

    ** , Seoung-Bae Park ** and Myung-Shik Won *** ABSTRACT The avoidance of enemy's radar detection is very important issue in the modern electronic weapon system. Researchers have been studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), \\

  4. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  5. Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

    SciTech Connect

    Huang, Xianjun, E-mail: xianjun.huang@manchester.ac.uk [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Hu, Zhirun [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Liu, Peiguo [College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-11-15

    This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications.

  6. Advanced Reflector and Absorber Materials (Fact Sheet)

    SciTech Connect

    Not Available

    2010-08-01

    Fact sheet describing NREL CSP Program capabilities in the area of advanced reflector and absorber materials: evaluating performance, determining degradation rates and lifetime, and developing new coatings.

  7. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J. (Oak Ridge, TN); Hamby, Jr., Clyde (Harriman, TN); Akerman, M. Alfred (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN)

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  8. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  9. Design and Manufacture of Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-05-28

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  10. Design and Manufacture of Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2014-05-30

    Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  11. Absorber Materials at Room and Cryogenic Temperatures

    SciTech Connect

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  12. Tech Transfer Webinar: Energy Absorbing Materials

    ScienceCinema

    Duoss, Eric

    2014-07-15

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  13. Tech Transfer Webinar: Energy Absorbing Materials

    SciTech Connect

    Duoss, Eric

    2014-06-17

    A new material has been designed and manufactured at LLNL that can absorb mechanical energy--a cushion--while also providing protection against sheering. This ordered cellular material is 3D printed using direct ink writing techniques under development at LLNL. It is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

  14. Engineering, Modeling and Testing of Composite Absorbing Materials for

    E-print Network

    Koledintseva, Marina Y.

    , the materials that would absorb electromagnetic energy in RF, microwave, and potentially mm-wave bands electromagnetic near-fields of the sources, or far-field electromagnetic waves of the given configuration of absorbing materials are of great importance as well. The materials must comply with requirements on thermal

  15. Numerical prediction of absorbing materials via Computational AeroAcoustics

    E-print Network

    Paris-Sud XI, Université de

    contributors, namely 1) the airframe noise, and 2) the propulsive noise. A way for reducing those noisesNumerical prediction of absorbing materials via Computational AeroAcoustics M. Escouflaire and S of the propulsive noise of airplanes, manufacturers are led to generalize the employment of "sound absorbing

  16. Determining factors for high performance silicone rubber microwave absorbing materials

    Microsoft Academic Search

    Hua Zou; Shuhuan Li; Liqun Zhang; Shani Yan; Hanguang Wu; Shuai Zhang; Ming Tian

    2011-01-01

    Silicone rubber microwave absorbing materials (RMAMs) based on ferrite as the major absorbent were prepared by the mechanical blending method. The determining factors for the complex permittivity, complex permeability, and reflectivity of RMAM were thoroughly investigated with various samples including different crystal structures of Ba-ferrite (M-type, W-type, and Y-type), the ferrite with doped elements (Ba, Sr), the materials' thickness, the

  17. EXAFS of Materials with Multiple Absorbing Sites

    Microsoft Academic Search

    Scott Calvin; Roman Izaac; Mihail Rivlin; M. L. Denboer

    2002-01-01

    Extended x-ray absorption fine structure (EXAFS) spectroscopy is widely used to investigate the short-range structure of many materials. Ordinarily the best results are obtained for materials in which each element whose absorption is measured occupies a single crystallographic site. However, in many important compounds a single element may occupy two or more distinct crystallographic sites. This complicates the analysis as

  18. EXAFS of Materials with Multiple Absorbing Sites

    Microsoft Academic Search

    Scott Calvin; Roman Iskhakov; Mihail Rivlin; M. L. Denboer

    2001-01-01

    Extended x-ray absorption fine structure (EXAFS) spectroscopy is widely used to investigate the short-range structure of many materials. Ordinarily the best results are obtained for materials in which each element whose absorption is measured occupies a single crystallographic site. However, in many important compounds a single element may occupy two or more distinct crystallographic sites. This complicates the analysis as

  19. Observation of ?-ray spectra after penetrating absorbing materials

    Microsoft Academic Search

    Y. Kawada; T. Yamada; J. Itoh; Y. Sato; A. Yunoki; Y. Hino

    2008-01-01

    ?-Ray spectra after penetrating absorbing materials of various thicknesses were observed by the use of a scintillation-type ?-ray spectrometer equipped with a flat NE-102 plastic scintillator of 5mm thickness for sources of 60Co, 90Sr–90Y, 137Cs, 147Pm and 204Tl. Although the spectra changed rapidly with increasing absorber thickness, the average ?-ray energy was kept nearly constant for a wider range. These

  20. Computation of radar absorbing silicon carbide foams and their silica matrix composites

    Microsoft Academic Search

    Hongtao Zhang; Jinsong Zhang; Hongyan Zhang

    2007-01-01

    SiC-foams and their composites were studied as novel stealthy materials by numerical simulations. The reflection coefficients of various SiC-foams are found to be strongly dependent on the SiC volume fractions, electric conductivities and frequency. A foaming SiC allows to reach high level of electromagnetic wave absorbing ability when the SiC volume fraction and the conductivity at proper values comparing to

  1. Permittivity and Permeability Extraction of Magnetically Loaded Absorbing Materials

    E-print Network

    . To extract permittivity and permeability parameters from measured scattering parameters following approaches and permeability extraction needs both transmission and reflection measurements and is very sensitive to noisy dataPermittivity and Permeability Extraction of Magnetically Loaded Absorbing Materials I.Zivkovic, A

  2. Determination of optical properties of absorbing materials: a generalized scheme.

    PubMed

    Nagendra, C L; Thutupalli, G K

    1983-02-15

    A generalized reflectance method for determination of optical properties of absorbing materials is developed and compared with other reflectance methods. In the present scheme the specimen is coated with dielectric transparent layer(s) and the reflectance ratios are measured. This novel scheme of specimen preparation and the method of measurement allow the specimen to be free from surface layers and at the same time account for possible effects of surface roughness. It can be applied to a wide variety of materials regardless of their surface conditions and is particularly useful for metals. PMID:18195831

  3. Fabrication and optimization of radar absorbing structures composed of glass\\/carbon fibers\\/epoxy laminate composites filled with carbon nanotubes

    Microsoft Academic Search

    Zhengquan Zhang; Tiehu Li; Deqi Jing; Qiang Zhuang

    2008-01-01

    The radar absorbing structures (RAS), which cannot only load bearing but absorb electromagnetic wave energy by inducing dielectric loss and minimize reflected waves, is a multifunctional composite. Therefore, many researchers have paid attention on the development of RAS. The essence of the RAS was reducing RCS of the object. The composites possess excellent specific stiffness and strength. The electromagnetic wave

  4. Absorbing materials with applications in radiotherapy and radioprotection.

    PubMed

    Spunei, M; Malaescu, I; Mihai, M; Marin, C N

    2014-11-01

    The radiotherapy centres are using linear accelerators equipped with multi-leaf collimators (MLCs) for treatments of various types of cancer. For superficial cancers located at a maximum depth of 3 cm high-energy electrons are often used, but MLC cannot be used together with electron applicators. Due to the fact that the tumour shape is not square (as electron applicators), searching for different materials that can be used as absorbents or shields for the protection of adjacent organs is of paramount importance. This study presents an experimental study regarding the transmitted dose through some laboratory-made materials when subjected to electron beams of various energies (ranging from 6 to 15 MeV). The investigated samples were composite materials consisting of silicon rubber and micrometre aluminium particles with different thicknesses and various mass fraction of aluminium. The measurements were performed at a source surface distance of 100 cm in the acrylic phantom. The experimental results show that the transmitted dose through tested samples is ranging between ?1.8 and 90%, depending on the electron beam energy, sample thickness and sample composition. These preliminary results suggest that the analysed materials can be used as absorbers or shields in different applications in radiotherapy and radioprotection. PMID:25071243

  5. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    NASA Astrophysics Data System (ADS)

    Zhong, Qiwen

    The conservation and transformation of energy is essential to the survival of mankind, and thus concerns every modern society. Solar energy, as an everlasting source of energy, holds one of the key solutions to some of the most urgent problems the world now faces, such as global warming and the oil crisis. Advances in technologies utilizing clean, abundant solar energy, could be the steering wheel of our societies. Solar cells, one of the major advances in converting solar energy into electricity, are now capturing people's interest all over the globe. While solar cells have been commercially available for many years, the manufacturing of solar cells is quite expensive, limiting their broad based implementation. The cost of solar cell based electricity is 15-50 cents per kilowatt hour (¢/kwh), depending on the type of solar cell, compared to 0.7 ¢/kwh for fossil fuel based electricity. Clearly, decreasing the cost of electricity from solar cells is critical for their wide spread deployment. This will require a decrease in the cost of light absorbing materials and material processing used in fabricating the cells. Organic photovoltaics (OPVs) utilize organic materials such as polymers and small molecules. These devices have the advantage of being flexible and lower cost than conventional solar cells built from inorganic semiconductors (e.g. silicon). The low cost of OPVs is tied to lower materials and fabrication costs of organic cells. However, the current power conversion efficiencies of OPVs are still below 15%, while convention crystalline Si cells have efficiencies of 20-25%. A key limitation in OPVs today is their inability to utilize the near infrared (NIR) portion of the solar spectrum. This part of the spectrum comprises nearly half of the energy in sunlight that could be used to make electricity. The first and foremost step in conversion solar energy conversion is the absorption of light, which nature has provided us optimal model of, which is photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

  6. Resolution function of nonsinusoidal radar signals. I - Range-velocity resolution with rectangular pulses

    Microsoft Academic Search

    Nasser J. Mohamed

    1990-01-01

    A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has recently attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by

  7. Resolution function of nonsinusoidal radar signals. I. Range-velocity resolution with rectangular pulses

    Microsoft Academic Search

    N. J. Mohamed

    1990-01-01

    A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by a

  8. Material Model Evaluation of a Composite Honeycomb Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

    2012-01-01

    A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

  9. Boron-copper neutron absorbing material and method of preparation

    DOEpatents

    Wiencek, Thomas C. (Bolingbrook, IL); Domagala, Robert F. (Indian Head Park, IL); Thresh, Henry (Palos Hts., IL)

    1991-01-01

    A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

  10. Alternative materials to cadmium for neutron absorbers in safeguards applications

    SciTech Connect

    Freeman, Corey R [Los Alamos National Laboratory; Geist, William H [Los Alamos National Laboratory; West, James D [Los Alamos National Laboratory

    2009-01-01

    Cadmium is increasingly difficult to use in safeguards applications because of rising cost and increased safety regulations. This work examines the properties of two materials produced by Ceradyne, inc. that present alternatives to cadmium for neutron shielding. The first is an aluminum metal doped with boron and the second is a boron carbide powder, compressed into a ceramic. Both are enriched in the {sup 10}B isotope. Two sheets of boron doped aluminum (1.1 mm and 5.2mm thick) and one sheet of boron carbide (8.5mm thick) were provided by Ceradyne for testing. An experiment was designed to test the neutron absorption capabilities of these three sheets against two different thicknesses of cadmium (0.6mm and 1.6mm thick). The thinner piece of aluminum boron alloy (1.1mm) performed as well as the cadmium pieces at absorbing neutrons. The thicker aluminum-boron plate provided more shielding than the cadmium sheets and the boron carbide performed best by a relatively large margin. Monte Carlo N-Particle eXtended (MCNPX) transport code modeling of the experiment was performed to provide validaLed computational tools for predicting the behavior of systems in which these materials may be incorporated as alternatives to cadmium. MCNPX calculations predict that approximately 0.17mm of the boron carbide is equivalent to 0.6mm of cadmium. There are drawbacks to these materials that need to be noted when considering using them as replacements for cadmium. Notably, they may need to be thicker than cadmium, and are not malleable, requiring machining to fit any curved forms.

  11. Radar

    Microsoft Academic Search

    James R. Zimbelman; Kenneth S. Edgett

    1994-01-01

    Over 1,000,000 km2 of the equatorial surface of Mars west of the Arsia Mons volcano displays no 3.5-cm radar echo to the very low level of the radar system noise for the Very Large Array; the area displaying this unique property has been terms \\

  12. Distribution of absorbed doses in the materials irradiated by \\

    Microsoft Academic Search

    A. KolchuzhkinJ; S. Korenev; O. Krivosheev; I. Tropin

    2001-01-01

    This paper describes the experimental setup and presents studies of absorbed doses in different metals and dielectrics along with corresponding Monte Carlo energy deposition simulations. Experiments were conducted using a 5 MeV electron accelerator. We used several Monte Carlo code systems, namely MARS, MCNP, and GEANT to simulate the absorbed doses under the same conditions as in experiment. We compare

  13. Numerical predictions for radar absorbing silicon carbide foams using a finite integration technique with a perfect boundary approximation

    Microsoft Academic Search

    Hongtao Zhang; Jinsong Zhang; Hongyan Zhang

    2006-01-01

    Modeling and prediction of electromagnetic wave absorbing properties of SiC foams as novel stealth materials in the X-band range of 8.2-12.4 GHz are presented. Appropriate material parameters, including the conductivity, volume fraction, cell size, thickness, and surface modified foam structure, are determined through optimization calculations, where the impedance difference between the SiC foam and free space is minimized. The minimum

  14. NREL Highlights SCIENCE Use of Earth-abundant materials in solar absorber films

    E-print Network

    NREL Highlights SCIENCE Use of Earth-abundant materials in solar absorber films is critical was proposed more than 25 years ago in the form of FeS2 pyrite--fool's gold. Unfortunately, the material has that can be used to identify new Fe-containing materials that can circumvent the limitations of FeS2 pyrite

  15. Investigation of the effectiveness of absorbent materials in oil spills clean up

    Microsoft Academic Search

    Ch. Teas; S. Kalligeros; F. Zanikos; S. Stournas; E. Lois; G. Anastopoulos

    2001-01-01

    The present study examines the absorption capacity of five different types of materials for oil spills clean up. The absorbents were a commercial cellulosic material from processed wood, a commercial synthetic organic fiber from polypropylene and three commercial types of local expanded perlite from the island of Milos. The absorption capacities of the above materials were evaluated in a wet

  16. Negative Refraction in a Uniaxial Absorbent Dielectric Material

    ERIC Educational Resources Information Center

    Jen, Yi-Jun; Lakhtakia, Akhlesh; Yu, Ching-Wei; Lin, Chin-Te

    2009-01-01

    Refraction of light from an isotropic dielectric medium to an anisotropic dielectric material is a complicated phenomenon that can have several different characteristics not usually discussed in electromagnetics textbooks for undergraduate students. With a simple problem wherein the refracting material is uniaxial with its optic axis normal to the…

  17. Levelized cost of coating (LCOC) for selective absorber materials.

    SciTech Connect

    Ho, Clifford Kuofei; Pacheco, James Edward

    2013-09-01

    A new metric has been developed to evaluate and compare selective absorber coatings for concentrating solar power applications. Previous metrics have typically considered the performance of the selective coating (i.e., solar absorptance and thermal emittance), but cost and durability were not considered. This report describes the development of the levelized cost of coating (LCOC), which is similar to the levelized cost of energy (LCOE) commonly used to evaluate alternative energy technologies. The LCOC is defined as the ratio of the annualized cost of the coating (and associated costs such as labor and number of heliostats required) to the average annual thermal energy produced by the receiver. The baseline LCOC using Pyromark 2500 paint was found to be %240.055/MWht, and the distribution of LCOC values relative to this baseline were determined in a probabilistic analysis to range from -%241.6/MWht to %247.3/MWht, accounting for the cost of additional (or fewer) heliostats required to yield the same baseline average annual thermal energy produced by the receiver. A stepwise multiple rank regression analysis showed that the initial solar absorptance was the most significant parameter impacting the LCOC, followed by thermal emittance, degradation rate, reapplication interval, and downtime during reapplication.

  18. Maxwellian material-based absorbing boundary conditions for lossy media in 3-D

    Microsoft Academic Search

    David C. Wittwer; Richard W. Ziolkowski

    2000-01-01

    A two time-derivative Lorentz material (2TDLM), which has been shown previously to be the correct Maxwellian medium choice to match an absorbing layer to a lossy region, is extended here to a complete absorbing boundary condition (ABC) for three-dimensional (3-D) finite-difference time-domain (FDTD) simulators. The implementation of the lossy 2TDLM (L2TDLM) ABC is presented. It is shown that in contrast

  19. Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material

    Microsoft Academic Search

    K. Sridharan; T. J. Renk; E. J. Lahoda; M. L Corradini

    2004-01-01

    Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added

  20. Absorber Materials for Transition-Edge Sensor X-ray Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Brown, Ari-David; Bandler, Simon; Brekosky, Regis; Chervenak, James; Figueroa-Feliciano, Enectali; Finkbeiner, Fred; Sadleir, Jack; Iyomoto, Naoko; Kelley, Richard; Kilbourne, Caroline; Porter, F. Scott; Smith, Stephen; Saab, Tarek; Sadleir, Jac,

    2007-01-01

    Arrays of superconducting transition-edge sensors (TES) can provide high spatial and energy resolution necessary for x-ray astronomy. High quantum efficiency and uniformity of response can be achieved with a suitable absorber material, in which absorber x-ray stopping power, heat capacity, and thermal conductivity are relevant parameters. Here we compare these parameters for bismuth and gold. We have fabricated electroplated gold, electroplated gold/electroplated bismuth, and evaporated gold/evaporated bismuth 8x8 absorber arrays and find that a correlation exists between the residual resistance ratio (RRR) and thin film microstructure. This finding indicates that we can tailor absorber material conductivity via microstructure alteration, so as to permit absorber thermalization on timescales suitable for high energy resolution x-ray microcalorimetry. We show that by incorporating absorbers possessing large grain size, including electroplated gold and electroplated gold/electroplated bismuth, into our current Mo/Au TES, devices with tunable heat capacity and energy resolution of 2.3 eV (gold) and 2.1 eV (gold/bismuth) FWHM at 6 keV have been fabricated.

  1. Identification of Potential Photovoltaic Absorbers Based on First-Principles Spectroscopic Screening of Materials

    SciTech Connect

    Yu, L.; Zunger, A.

    2012-02-10

    There are numerous inorganic materials that may qualify as good photovoltaic (PV) absorbers, except that the currently available selection principle - focusing on materials with a direct band gap of {approx}1.3 eV (the Shockley-Queisser criteria) - does not provide compelling design principles even for the initial material screening. Here we offer a calculable selection metric of 'spectroscopic limited maximum efficiency (SLME)' that can be used for initial screening based on intrinsic properties alone. It takes into account the band gap, the shape of absorption spectra, and the material-dependent nonradiative recombination losses. This is illustrated here via high-throughput first-principles quasiparticle calculations of SLME for {approx}260 generalized I{sub p}III{sub q}VI{sub r} chalcopyrite materials. It identifies over 20 high-SLME materials, including the best known as well as previously unrecognized PV absorbers.

  2. Computed phase equilibria for burnable neutron absorbing materials for advanced pressurized heavy water reactors

    NASA Astrophysics Data System (ADS)

    Corcoran, E. C.; Lewis, B. J.; Thompson, W. T.; Hood, J.; Akbari, F.; He, Z.; Reid, P.

    2009-03-01

    Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for the Advanced CANDU ®[CANDU is as a registered trademark of Atomic Energy of Canada Limited.] Reactor. The neutron absorbing material is composed of gadolinia and dysprosia dissolved in an inert cubic-fluorite yttria-stabilized zirconia matrix. A thermodynamic model based on Gibbs energy minimization has been created to provide estimated phase equilibria as a function of composition and temperature. This work includes some supporting experimental studies involving X-ray diffraction.

  3. Development of a Weldable Neutron Absorbing Structural Material

    SciTech Connect

    R. E. Mizia; W. L. Hurt; C. V. Robino; J. N. DuPont

    2006-04-01

    The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory, coordinates and integrates national efforts in management and disposal of U.S. Department of Energy (DOE)-owned spent nuclear fuel. These management functions include development of standardized systems for packaging, storage, treatment, transport, and long-term disposal in the proposed Yucca Mountain Repository. Nuclear criticality control measures are needed in these systems to avoid restrictive fissile loading limits because of the enrichment and total quantity of fissile material in some types of the DOE spent nuclear fuel. This paper will outline the results to date of a metallurgical development program that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this program includes chemical composition definition, primary melting and secondary refining studies, ingot conversion process evaluations, mechanical/physical properties and corrosion testing, welding studies, and national consensus codes, and standards work.

  4. Acoustic behavior of a fibrous bulk material. [Kevlar 29 sound absorber

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Walker, B.

    1979-01-01

    A semiempirical model is presented describing the acoustic behavior of Kevlar 29, a bulk absorbing material. The model is based on an approximate solution to the one-dimensional equations representing conservation of fluctuating mass, momentum and energy. By treating the material as a momentum sink, theoretical expressions of the material complex propagation constants and characteristic impedance were derived in terms of a single constant. Evaluating the constant at a single frequency for a particular specimen, excellent agreement between prediction and measurement was achieved for a large range of sound frequencies and material porosities and thicknesses. Results show that Kevlar 29 absorbs sound efficiently even at low frequencies. This is explained in terms of a frequency dependent material phase speed.

  5. Absorbent Material

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A superabsorbent fabric developed by Johnson Space Center and described in Tech Briefs was adapted by Honeywell and fabricated into special containment devices used on Navy "smart" torpedos. The superabsorbent fabric can sequester up to 400 times its own weight in water and protects the torpedo electronic controls from possible short circuiting by deepwater hull seepage.

  6. Realizing thin electromagnetic absorbers for wide incidence angles from commercially available planar circuit materials

    SciTech Connect

    Glover, Brian B [Los Alamos National Laboratory; Whites, Kieth W [SDSMT; Radway, Matthew J [CU-BOULDER

    2009-01-01

    In this study, recent work on engineering R-card surface resistivity with printed metallic patterns is extended to the design of thin electromagnetic absorbers. Thin electromagnetic absorbers for wide incidence angles and both polarizations have recently been computationally verified by Luukkonen et al.. These absorbers are analytically modeled high-impedance surfaces with capacitive arrays of square patches implemented with relatively high dielectric constant and high loss substrate. However, the advantages provided by the accurate analytical model are largely negated by the need to obtain high dielectric constant material with accurately engineered loss. Fig. I(c) illustrates full-wave computational results for an absorber without vias engineered as proposed by Luukkonen et al.. Unique values for the dielectric loss are required for different center frequencies. Parameters for the capacitive grid are D=5.0 mm and w=O.l mm for a center frequency of 3.36 GHz. The relative permittivity and thickness is 9.20(1-j0.234) and 1=3.048 mm. Consider a center frequency of5.81 GHz and again 1=3.048 mm, the required parameters for the capacitive grid are D=2.0 mm and w=0.2 mm where the required relative permittivity is now 9.20(1-j0.371) Admittedly, engineered dielectrics are themselves a historically interesting and fruitful research area which benefits today from advances in monolithic fabrication using direct-write of dielectrics with nanometer scale inclusions. However, our objective in the present study is to realize the advantages of the absorber proposed by Luukkonen et al. without resort to engineered lossy dielectrics. Specifically we are restricted to commercially available planer circuit materials without use of in-house direct-write technology or materials engineering capability. The materials considered here are TMM 10 laminate with (35 {mu}lm copper cladding with a complex permittivity 9.20-j0.0022) and Ohmegaply resistor conductor material (maximum 250 {Omega}/sq.). A thin electromagnetic absorber for incidence angles greater than 30deg. but less than 60deg. and both polarizations is computationally demonstrated. This absorber utilizes high-permittivity, low-loss microwave substrate in conjunction with an engineered lossy sheet impedance. The lossy sheet impedance is easily engineered with simple analytical approximations and can be manufactured from commercially available laminate materials on microwave substrate.

  7. Research and application of kapok fiber as an absorbing material: a mini review.

    PubMed

    Zheng, Yian; Wang, Jintao; Zhu, Yongfeng; Wang, Aiqin

    2015-01-01

    Kapok fiber corresponds to the seed hairs of the kapok tree (Ceiba pentandra), and is a typical cellulosic fiber with the features of thin cell wall, large lumen, low density and hydrophobic-oleophilic properties. As a type of renewable natural plant fiber, kapok fiber is abundant, biocompatible and biodegradable, and its full exploration and potential application have received increasing attention in both academic and industrial fields. Based on the structure and properties of kapok fiber, this review provides a summary of recent research on kapok fiber including chemical and physical treatments, kapok fiber-based composite materials, and the application of kapok fiber as an absorbent material for oils, metal ions, dyes, and sound, with special attention to its use as an oil-absorbing material, one predominant application of kapok fiber in the coming future. PMID:25597659

  8. Layout of Sound Absorbing Materials in 3D Rooms Using Damping Contributions with Eigenvectors as Weight Coefficients

    Microsoft Academic Search

    Takao Yamaguchi; Junichi Tsugawa; Hideki Enomoto; Yoshio Kurosawa

    2010-01-01

    In this study, we estimate an efficient layout of sound absorbing materials in three-dimensional spaces. For this purpose, we use damping contributions with eigenvectors as weight coefficients. Three-dimensional finite Elements of absorbing materials are modeled using a complex effective density and a complex bulk modulus of elasticity. By expanding the solution of complex eigenvalue problem with a small parameter related

  9. Decontamination of skin exposed to nanocarriers using an absorbent textile material and PEG-12 dimethicone

    NASA Astrophysics Data System (ADS)

    Lademann, J.; Richter, H.; Baier, G.; Landfester, K.; Frazier, L.; Gefeller, H.; Wunderlich, U.; Gross, I.; Rühl, E.; Knorr, F.

    2014-11-01

    The removal of noxious particulate contaminants such as pollutants derived from particle-to-gas conversions from exposed skin is essential to avoid the permeation of potentially harmful substances into deeper skin layers via the stratum corneum or the skin appendages and their dispersion throughout the circulatory system. This study is aimed at evaluating the efficacy of using the silicone glycol polymer PEG-12 dimethicone and an absorbent textile material to remove fluorescing hydroxyethyl starch nanocapsules implemented as model contaminants from exposed porcine ear skin. Using laser scanning microscopy, it could be shown that while the application and subsequent removal of the absorbent textile material alone did not result in sufficient decontamination, the combined application with PEG-12 dimethicone almost completely eliminated the nanocapsules from the surface of the skin. By acting as a wetting agent, PEG-12 dimethicone enabled the transfer of the nanocapsules into a liquid phase which was taken up by the absorbent textile material. Only traces of fluorescence remained detectable in several skin furrows and follicular orifices, suggesting that the repeated implementation of the procedure may be necessary to achieve total skin surface decontamination.

  10. Investigation of titanium and polyethylene as UCN absorber materials with AbEx

    NASA Astrophysics Data System (ADS)

    Picker, R.; Altarev, I.; Amos, P.; Franke, B.; Geltenbort, P.; Gutsmiedl, E.; Hartmann, F. J.; Mann, A.; Materne, S.; Müller, A. R.; Paul, S.; Stoepler, R.; Wirth, H.-F.

    2009-12-01

    Marginally trapped neutrons are a major source of systematic errors in storage experiments with ultra-cold neutrons (UCN): their energies slightly exceed the trapping potential and their storage lifetimes are of the same order of magnitude as the neutron ?-decay lifetime to be measured. Hence, they have to be removed before the actual neutron storage period starts. For the magneto-gravitational neutron-lifetime experiment PENeLOPE, a novel absorber scheme was proposed; its efficiency to reduce the systematic influence of marginally trapped UCN on the extracted ?-decay lifetime value had to be investigated. To this end, the cryogenic material-storage experiment AbEx ( Ab sorber Ex periment) was conducted at ILL, Grenoble; neutron-optical properties of storage and absorption materials were investigated. Storage lifetimes shorter than 10 s could be reached for high-energy UCN with the proposed scheme. This translates to a systematic effect on the neutron-lifetime measurement with PENeLOPE of ??n<0.03 s. Polyethylene (PE) and titanium were tested as absorber materials. The temperature dependence of their UCN absorbing efficiency was determined to be rather small and connected not with the upscattering cross-section, but probably with surface contaminations.

  11. Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite

    Microsoft Academic Search

    Y. B. Feng; T. Qiu; C. Y. Shen

    2007-01-01

    Carbonyl iron and barium ferrite powder (BaZn1.5Co0.5Fe16O27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2–18GHz was

  12. Absorbing properties and structural design of microwave absorbers based on carbonyl iron and barium ferrite

    Microsoft Academic Search

    Y. B. Feng; T. Qiu; C. Y. Shen

    2007-01-01

    Carbonyl iron and barium ferrite powder (BaZn1.5Co0.5Fe16O27) were prepared in this work. The complex permittivity and permeability spectra for rubber radar absorbing materials employing carbonyl iron and barium ferrite powders were measured. A database describing the frequency dependence of the permittivities and permeabilities of the carbonyl iron and barium ferrite microwave absorbers with various powder percentage compositions in 2 18

  13. Absorb & Repel

    NSDL National Science Digital Library

    Kohl Children's Museum

    2012-01-01

    In this activity, learners investigate how different materials repel or absorb water. Learners use spray bottles to explore how everyday items like sponges, cardboard, feathers, etc. respond to water differently. This activity also introduces learners to the scientific method as learners make predictions about which materials will absorb or repel water.

  14. Development of microwave absorbing materials prepared from a polymer binder including Japanese lacquer and epoxy resin

    NASA Astrophysics Data System (ADS)

    Iwamaru, T.; Katsumata, H.; Uekusa, S.; Ooyagi, H.; Ishimura, T.; Miyakoshi, T.

    Microwave absorption composites were synthesized from a poly urushiol epoxy resin (PUE) mixed with one of microwave absorbing materials; Ni-Zn ferrite, Soot, Black lead, and carbon nano tube (CNT) to investigate their microwave absorption properties. PUE binders were specially made from Japanese lacquer and epoxy resin, where Japanese lacquer has been traditionally used for bond and paint because it has excellent beauty. Japanese lacquer solidifies with oxygen contained in air's moisture, which has difficulty in making composite, but we improved Japanese lacquer's solidification properties by use of epoxy resin. We made 10 mm thickness composite samples and cut them into toroidal shape to measure permittivity, permeability, and reflection loss in frequencies ranging from 50 Hz to 20 GHz. Electric magnetic absorber's composites synthesized from a PUE binders mixed either with Soot or CNT showed significantly higher wave absorption over -27 dB than the others at frequencies around 18 GHz, although Japanese lacquer itself doesn't affect absorption. This means Japanese lacquer can be used as binder materials for microwave absorbers.

  15. Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object

    DOEpatents

    Crane, Thomas W. (Los Alamos, NM)

    1986-01-01

    The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

  16. Method and apparatus for determining the content and distribution of a thermal neutron absorbing material in an object

    DOEpatents

    Crane, T.W.

    1983-12-21

    The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The object is placed between the neutron generator and the neutron detector. The reduction in the neutron flux corresponds to the amount of thermal neutron absorbing material in the object. The object is advanced past the neutron generator and neutron detector to obtain neutron flux data for each segment of the object. The object may comprise a space reactor heat pipe and the thermal neutron absorbing material may comprise lithium.

  17. A Doppler Radar for Measuring Irregularities in Rolled Sheet Material

    Microsoft Academic Search

    Frank G. Alexander

    1963-01-01

    This 9-Gc system used a microwave signal reflected from the surface of a rotating roll of paper or plastic film to detect irregularities in the outer layers of the rolled material. The microwave package comprised a klystron oscillator, silicon dector crystal, and flared wave-guide horn antenna. A standard laboratory oscilloscope was used as the ``receiver'' and display system. Examples of

  18. Nanostructured thin film-based near-infrared tunable perfect absorber using phase-change material

    NASA Astrophysics Data System (ADS)

    Kocer, Hasan

    2015-01-01

    Nanostructured thin film absorbers embedded with phase-change thermochromic material can provide a large level of absorption tunability in the near-infrared region. Vanadium dioxide was employed as the phase-change material in the designed structures. The optical absorption properties of the designed structures with respect to the geometric and material parameters were systematically investigated using finite-difference time-domain computations. Absorption level of the resonance wavelength in the near-IR region was tuned from the perfect absorption level to a low level (17%) with a high positive dynamic range of near-infrared absorption intensity tunability (83%). Due to the phase transition of vanadium dioxide, the resonance at the near-infrared region is being turned on and turned off actively and reversibly under the thermal bias, thereby rendering these nanostructures suitable for infrared camouflage, emitters, and sensors.

  19. [New surgical technique of pulmonary segmentectomy by ultrasonic scalpel and absorbable sealing materials].

    PubMed

    Matsumura, Y; Okada, Y; Shimada, K; Endo, C; Chida, M; Sakurada, A; Sato, M; Kondo, T

    2004-01-01

    We developed new surgical technique of pulmonary segmentectomy by ultrasonic scalpel to sever intersegmental pulmonary tissue and absorbable sealing materials to cover the cut surface of lung. This method is expected to preserve more anatomical lung volume than the segmentectomy with surgical stapler. Two cases of post surgical recurrent lung cancer, 3 cases of pulmonary metastasis and 4 cases of primary lung cancer were applied this technique to preserve function. Among 3 materials examined, best result was obtained with polyglycolic acid felt (PGAF:Neoveil). PGAF is a very soft and thin (0.15 mm depth) new absorbable material that is able to closely adhere to irregular sections of the lung with fibrin glue and effectively seals air leakage. Mean chest drainage period after surgery in 6 cases with PGAF was 3.3 days. Excellent lung expansion was obtained immediately after the surgery and PGAF was disappeared completely on chest CT within 1 year. Although the possible superiority of this method is suggested in the present study, further comparative study is necessary to clarify the advantage of this new technique. PMID:14733096

  20. Scientists Identify New Quaternary Materials for Solar Cell Absorbers (Fact Sheet), NREL Highlights, Science

    SciTech Connect

    Not Available

    2011-10-01

    Research provides insight for exploring use of earth-abundant quaternary semiconductors for large-scale solar cell applications. For large-scale solar electricity generation, it is critical to find new material that is Earth abundant and easily manufactured. Previous experimental studies suggest that Cu{sub 2}ZnSnS{sub 4} could be a strong candidate absorber materials for large-scale thin-film solar cells due to its optimal bandgap, high adsorption coefficient, and ease of synthesis. However, due to the complicated nature of the quaternary compound, it is unclear whether other quaternary compounds have physical properties suitable for solar cell application. Researchers at the National Renewable Energy Laboratory (NREL), Fudan University, and University College London have performed systematic searches of quaternary semiconductors using a sequential cation mutation method in which the material properties of the quaternary compounds can be derived and understood through the evolution from the binary, to ternary, and to quaternary compounds. The searches revealed that in addition to Cu{sub 2}ZnSnS{sub 4}, Cu{sub 2}ZnGeSe{sub 4} and Cu{sub 2}ZnSnSe{sub 4} are also suitable quaternary materials for solar cell absorbers. Through the extensive study of defect and alloy properties of these materials, the researchers propose that to maximize solar cell performance, growth of Cu{sub 2}ZnSnS{sub 4} under Cu-poor/Zn-rich conditions will be optimal and the formation of Cu{sub 2}ZnSn(S,Se){sub 4} alloy will be beneficial in improving solar cell performance.

  1. Efficient positioning of absorbing material in complex systems by using the Patch Transfer Function method

    NASA Astrophysics Data System (ADS)

    Totaro, N.; Guyader, J. L.

    2012-06-01

    Given the need to decrease energy consumption in the automobile industry, vehicle weight has become an important issue. Regarding acoustic comfort, the weight of noise reduction devices must be minimized inside vehicle compartments. Consequently, these devices, for example those using poro-elastic materials, must be designed carefully to maximize their influence on noise reduction. The present paper describes a method developed to obtain an efficient positioning of a given surface (or mass) of absorbing material characterized by its surface impedance. This technique is based on the Patch Transfer Function method used to couple complex vibro-acoustic sub-domains and which has been successfully applied in the European ViSPeR and Silence projects. First, a numerical analysis of the possibilities of this method is performed on a non-rectangular cavity with rigid walls after which an experimental validation of this numerical analysis is performed to evaluate the accuracy of the method under real conditions.

  2. Measurements of the light-absorbing material inside cloud droplets and its effect on cloud albedo

    NASA Technical Reports Server (NTRS)

    Twohy, C. H.; Clarke, A. D.; Warren, Stephen G.; Radke, L. F.; Charleson, R. J.

    1990-01-01

    Most of the measurements of light-absorbing aerosol particles made previously have been in non-cloudy air and therefore provide no insight into aerosol effects on cloud properties. Here, researchers describe an experiment designed to measure light absorption exclusively due to substances inside cloud droplets, compare the results to related light absorption measurements, and evaluate possible effects on the albedo of clouds. The results of this study validate those of Twomey and Cocks and show that the measured levels of light-absorbing material are negligible for the radiative properties of realistic clouds. For the measured clouds, which appear to have been moderately polluted, the amount of elemental carbon (EC) present was insufficient to affect albedo. Much higher contaminant levels or much larger droplets than those measured would be necessary to significantly alter the radiative properties. The effect of the concentrations of EC actually measured on the albedo of snow, however, would be much more pronounced since, in contrast to clouds, snowpacks are usually optically semi-infinite and have large particle sizes.

  3. Comparative study of the holding strength of slipknots using absorbable and nonabsorbable ligature materials.

    PubMed

    Shimi, S M; Lirici, M; Vander Velpen, G; Cuschieri, A

    1994-11-01

    The holding and tensile characteristics of five extracorporeal slipknots in relation to absorbable and nonabsorbable ligature materials have been evaluated in a standardized in vitro test rig. The knots studied: Tayside, Roeder, Melzer (modified Roeder), Cross square, and Blood knots were tied with the following materials: silk, polyamide, Dacron, polydioxanone (PDS), and lactomer (Polysorb). Following construction and slippage (run down) to a fixed-diameter loop around a cylinder, the knots were locked (tightened) using a standardized force after which they were removed from the test rig and subjected to holding strength (force required to induce reverse slippage) and other tensile characteristics (stress, strain, elasticity) by a tensiometer. Analysis of the data has demonstrated the following: (1) The safest slip knots (resist slippage) are the Tayside, Melzer, and Roeder knots tied with lactomer and Dacron. (2) The holding strengths of the Cross square and Blood knots are weak with all ligature materials tested. (3) Polydioxanone is a safe ligature material for the Melzer and Tayside but not the Roeder knot. (4) Extracorporeal slipknots tied with silk and polyamide are less secure than the equivalent knots tied with Dacron, lactomer, and polydioxanone. PMID:7831597

  4. Black phosphorus a new saturable absorber material for ultrashort pulse generation

    E-print Network

    Sotor, Jaroslaw; Macherzynski, Wojciech; Paletko, Piotr; Abramski, Krzysztof M

    2015-01-01

    Low-dimensional materials, due to their versatile properties are very interesting for numerous electronics and optoelectronics applications. Recently rediscovered black phosphorus, with a graphite-like structure can be exfoliated up to the single atomic layer. In contrary to graphene it possesses a direct band gap controllable by the number of stacked atomic layers. For those reasons, it is now intensively investigated. Here we demonstrate, that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation. The mechanically exfoliated ~300 nm thick layers of black phosphorus were transferred onto the fiber core and under pulsed excitation at 1560 nm wavelength its transmission increases by 4.4%. It was used to generate 272 fs-short pulses at 1550 nm and 739 fs at 1910 nm. The obtained results shows that black phosphorus can be effectively used for ultrashort pulse generation and proves its great potential to future applications.

  5. Resolution function of nonsinusoidal radar signals. I - Range-velocity resolution with rectangular pulses

    NASA Astrophysics Data System (ADS)

    Mohamed, Nasser J.

    1990-05-01

    A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has recently attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by a look-down radar, which calls for a thumbtack ambiguity function. Since a small radar cross section in this application is typically due to the small size of the target that is coated with absorbing material, the antistealth feature of the nonsinusoidal radar is implicitly being used. The principle is presented of a resolution function (tentatively called the range-velocity or the range-Doppler resolution function) based on processing a nonsinusoidal signal consisting of N characters with a time separation TD and each character consisting of a sequence of L binary pulses of duration T. It is shown that range-velocity resolution functions approaching the ideal thumbtack function are easy to obtain. The blind speeds of the pulse-Doppler radar with sinusoidal carrier do not inherently occur, and all velocities are observed as true velocities rather than as velocities modulo the first blind speed (velocity ambiguity).

  6. Characterization of volcanic materials using ground penetrating radar: A case study at Teide volcano (Canary Islands, Spain)

    Microsoft Academic Search

    D. Gómez-Ortiz; S. Martín-Velázquez; T. Martín-Crespo; A. Márquez; J. Lillo; I. López; F. Carreño

    2006-01-01

    Ground penetrating radar (GPR) is a useful geophysical technique that can be used to characterize the nature, geometry and spatial distribution of subsurface volcanic materials, being these valuable data to complete field observations in those areas where information obtained from the surface is restricted. We have analyzed the GPR response in several volcanic materials (massive and heterogeneous lava flows, pahoehoe

  7. Modeling Dielectric-constant values of Geologic Materials: An Aid to Ground-Penetrating Radar Data Collection and Interpretation

    Microsoft Academic Search

    Alex Martinez; Alan P. Byrnes

    2001-01-01

    Ground-penetrating radar (GPR) is a near-surface geophysical imaging technique used for non- intrusive subsurface geologic and engineering investigations. Dielectric constant is a critical parameter for GPR surveys because it controls propagation velocity of electromagnetic waves through material, reflection coefficients across interfaces of different materials, and vertical and horizontal imaging resolution. Dielectric constant in rocks and sediments is primarily a function

  8. 2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications.

    PubMed

    Cao, Duyen H; Stoumpos, Constantinos C; Farha, Omar K; Hupp, Joseph T; Kanatzidis, Mercouri G

    2015-06-24

    We report on the fabrication and properties of the semiconducting 2D (CH3(CH2)3NH3)2(CH3NH3)n-1PbnI3n+1 (n = 1, 2, 3, and 4) perovskite thin films. The band gaps of the series decrease with increasing n values, from 2.24 eV (CH3(CH2)3NH3)2PbI4 (n = 1) to 1.52 eV CH3NH3PbI3 (n = ?). The compounds exhibit strong light absorption in the visible region, accompanied by strong photoluminescence at room temperature, rendering them promising light absorbers for photovoltaic applications. Moreover, we find that thin films of the semi-2D perovskites display an ultrahigh surface coverage as a result of the unusual film self-assembly that orients the [PbnI3n+1](-) layers perpendicular to the substrates. We have successfully implemented this 2D perovskite family in solid-state solar cells, and obtained an initial power conversion efficiency of 4.02%, featuring an open-circuit voltage (Voc) of 929 mV and a short-circuit current density (Jsc) of 9.42 mA/cm(2) from the n = 3 compound. This result is even more encouraging considering that the device retains its performance after long exposure to a high-humidity environment. Overall, the homologous 2D halide perovskites define a promising class of stable and efficient light-absorbing materials for solid-state photovoltaics and other applications. PMID:26020457

  9. Orbital Radar Response of Near Surface Materials in Southern Egypt and Implications for Cenozoic History

    NASA Astrophysics Data System (ADS)

    Maxwell, T. A.; Grant, J. A.; Johnston, A. K.

    2004-05-01

    Although the existence of "trunk" and tributary drainage channels beneath the sand in the northeast Sahara has been known for two decades, data from the SIR-C mission continues to be useful in solving geologic problems and understanding the radar response from specific types of near surface materials. In the Kiseiba Oasis region of southwest Egypt, SIR-C data revealed a complex tributary pattern of varying brightness that indicated the presence of paleodrainage not noted in the field. The orbital imaging radar uniquely specified key areas for detailed field studies that were not apparent in visible wavelengths. Twenty-two trenches up to 3 m deep, hundreds of shallow pits, several auger holes, and ground penetrating radar reveal that this area has had a history of fluctuating climatic conditions responsible for excavation and enlargement of the local depression by fluvial erosion and preservation of relict surfaces by aeolian blanketing of sand sheet deposits. The resulting near-surface stratigraphy is a complex mixture of fluvial pebble lags in the subsurface and on the surface, where aeolian mixing and local transport have modified the original geometry. In L-band (23 cm wavelength) SIR-C data, a hierarchy of returned signal strength and geometric patterns enables us to predict the type of surface and near-surface materials, sequentially from shallow bedrock to subsurface and surficial lags to sand sheet-veneered weathered anhydrite. Integrating the pattern of sedimentary deposits with relict channels and interfluves enables a better understanding of the origin of the Kiseiba-Dungul depression and its Cenozoic history. What was once thought to be a continuous deposit of Eocene limestone from southern Egypt into northern Sudan is cast in doubt as even the most optimistic estimates of scarp retreat don't permit hundred's of kms of retreat to the present position. Instead, the E-W pattern of the depression, the relict hills, and fracture zones all suggest structural control and erosion patterns that started with N-S compression in the latest Cretaceous. A humid climate during the Tertiary aided fluvial dissection of the broken surface, with drainage leading to the north into the present Kharga depression. The drainage patterns of the Quaternary seen now in orbital radar result from remnants of large-scale structural patterns and Tertiary drainage, confused by alternating hyperarid and semiarid climatic cycles that inverted topography, protected former erosion surfaces, and reversed drainage.

  10. Heat defect of low energy X-rays in some materials of interest in absorbed dose calorimetry

    Microsoft Academic Search

    M. Saebel; Th. Schmidt; H. Pauly

    1974-01-01

    Summary The amount of energy absorbed in material and not converted to heat is identical with the (negative or positive) heat of reactions and other processes induced by radiation. This fraction of energy is called “heat defect”. In order to determine the heat defect, which is generally a very small effect, a precise isothermal twin calorimeter was constructed [description see

  11. Rice straw-wood particle composite for sound absorbing wooden construction materials.

    PubMed

    Yang, Han-Seung; Kim, Dae-Jun; Kim, Hyun-Joong

    2003-01-01

    In this study, rice straw-wood particle composite boards were manufactured as insulation boards using the method used in the wood-based panel industry. The raw material, rice straw, was chosen because of its availability. The manufacturing parameters were: a specific gravity of 0.4, 0.6, and 0.8, and a rice straw content (10/90, 20/80, and 30/70 weight of rice straw/wood particle) of 10, 20, and 30 wt.%. A commercial urea-formaldehyde adhesive was used as the composite binder, to achieve 140-290 psi of bending modulus of rupture (MOR) with 0.4 specific gravity, 700-900 psi of bending MOR with 0.6 specific gravity, and 1400-2900 psi of bending MOR with a 0.8 specific gravity. All of the composite boards were superior to insulation board in strength. Width and length of the rice straw particle did not affect the bending MOR. The composite boards made from a random cutting of rice straw and wood particles were the best and recommended for manufacturing processes. Sound absorption coefficients of the 0.4 and 0.6 specific gravity boards were higher than the other wood-based materials. The recommended properties of the rice straw-wood particle composite boards are described, to absorb noises, preserve the temperature of indoor living spaces, and to be able to partially or completely substitute for wood particleboard and insulation board in wooden constructions. PMID:12653275

  12. ANNUAL REPORT. MATERIAL PROPERTY ESTIMATION FOR DIRECT DETECTION OF DNAPL USING INTEGRATED GROUND-PENETRATING RADAR VELOCITY, IMAGING, AND ATTRIBUTE ANALYSIS

    EPA Science Inventory

    The focus of our work is direct detection of DNAPLs, specifically chlorinated solvents, via material property estimation from surface ground-penetrating radar (GPR) data. We combine sophisticated GPR processing methodology with quantitative attribute analysis and material propert...

  13. Reaction behavior of B sub 4 C absorber material with stainless steel and Zircaloy in severe light water reactor accidents

    Microsoft Academic Search

    P. Hofmann; M. E. Markiewicz; J. L. Spino

    1990-01-01

    The chemical reaction behavior of BâC absorber material with stainless steel 1.4919 (type 316) and Zircaloy-4 is studied in the 800 to 1600°C temeprature range. The reaction kinetics for both systems can be described by parabolic rate laws. Above 100°C, the reaction zone growth rates in the BâC\\/stainless steel system are about two orders of magnitude higher than those in

  14. The use of slow waves to design simple sound absorbing materials

    NASA Astrophysics Data System (ADS)

    Groby, J.-P.; Huang, W.; Lardeau, A.; Aurégan, Y.

    2015-03-01

    We demonstrate that the phenomenon of slow sound propagation associated with its inherent dissipation (dispersion + attenuation) can be efficiently used to design sound absorbing metamaterials. The dispersion relation of the wave propagating in narrow waveguides on one side of which quarter-wavelength resonators are plugged with a square lattice, whose periodicity is smaller than the wavelength, is analyzed. The thermal and viscous losses are accounted for in the modeling. We show that this structure slows down the sound below the bandgap associated with the resonance of quarter-wavelength resonators and dissipates energy. After deriving the effective parameters of both such a narrow waveguide and a periodic arrangement of them, we show that the combination of slow sound together with the dissipation can be efficiently used to design a sound absorbing metamaterial which totally absorbs sound for wavelength much larger than four times the thickness structure. This last claim is supported by experimental results.

  15. Nonlinear inversion of borehole-radar tomography data to reconstruct velocity and attenuation distribution in earth materials

    USGS Publications Warehouse

    Zhou, C.; Liu, L.; Lane, J.W., Jr.

    2001-01-01

    A nonlinear tomographic inversion method that uses first-arrival travel-time and amplitude-spectra information from cross-hole radar measurements was developed to simultaneously reconstruct electromagnetic velocity and attenuation distribution in earth materials. Inversion methods were developed to analyze single cross-hole tomography surveys and differential tomography surveys. Assuming the earth behaves as a linear system, the inversion methods do not require estimation of source radiation pattern, receiver coupling, or geometrical spreading. The data analysis and tomographic inversion algorithm were applied to synthetic test data and to cross-hole radar field data provided by the US Geological Survey (USGS). The cross-hole radar field data were acquired at the USGS fractured-rock field research site at Mirror Lake near Thornton, New Hampshire, before and after injection of a saline tracer, to monitor the transport of electrically conductive fluids in the image plane. Results from the synthetic data test demonstrate the algorithm computational efficiency and indicate that the method robustly can reconstruct electromagnetic (EM) wave velocity and attenuation distribution in earth materials. The field test results outline zones of velocity and attenuation anomalies consistent with the finding of previous investigators; however, the tomograms appear to be quite smooth. Further work is needed to effectively find the optimal smoothness criterion in applying the Tikhonov regularization in the nonlinear inversion algorithms for cross-hole radar tomography. ?? 2001 Elsevier Science B.V. All rights reserved.

  16. Mode-locked Nd: GdVO4 laser with graphene oxide/polyvinyl alcohol composite material absorber as well as an output coupler

    NASA Astrophysics Data System (ADS)

    Wang, YongGang; Chen, Houren; Hsieh, Wenfeng; Tsang, YuenHong

    2013-02-01

    Graphene oxide/polyvinyl alcohol (GO/PVA) composite material saturable absorbers were fabricated. Sandwich structured GO/PVA absorber was used as an absorber as well as an output coupler in mode-locked Nd: GdVO4 laser. The laser pulses with the duration of 12 ps, repetition rate of 120 MHz and the maximum average output power of 680 mW were produced.

  17. Microstructural Characterization of Burnable Absorber Materials Being Evaluated for Application in LEU U-Mo Fuel Plates

    SciTech Connect

    J. F. Jue; B. Miller; B. Yao; E. Perez; Y. H. Sohn

    2011-03-01

    The starting microstructure of a fuel plate will impact how it performs during irradiation. As a result, microstructural characterization has been performed on as-fabricated monolithic fuel plates to determine the changes in fuel plate microstructure that may result from changes in fabrication parameters. Particular focus has been given to the fuel plate U-10Mo/Zr and Zr/AA6061 cladding interfaces, since the integrity of these interfaces will play a big role in determining the overall performance of the fuel plate during irradiation. In addition, burnable absorber materials for potential incorporation into monolithic fuel plates have been characterized to identify their as-fabricated microstructures. This information will be important when trying to understand the PIE data from fuel plates with burnable absorbers that are irradiated in future irradiation experiments. This paper will focus on the microstructures observed using optical metallography, X-ray diffraction, and scanning and transmission electron microscopy for monolithic fuel plates exposed to different fabrication parameters and for as-fabricated burnable absorber materials.

  18. Lunar radar backscatter studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1979-01-01

    The lunar surface material in the Plato area is characterized using Earth based visual, infrared, and radar signatures. Radar scattering in the lunar regolith with an existing optical scattering computer program is modeled. Mapping with 1 to 2 km resolution of the Moon using a 70 cm Arecibo radar is presented.

  19. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K. (Aiken, SC); Wicks, George G. (Aiken, SC); Enz, Glenn L. (N. Augusta, SC)

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  20. Preparation and study on microwave absorbing materials of boron nitride coated pyrolytic carbon particles

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Xiao, Peng; Li, Yang

    2012-09-01

    Boron nitride coatings were synthesized on pyrolytic carbon (BN-coated PyC) particles via chemical reaction of boric acid and urea in nitrogen. The results of Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FI-IR) and X-ray photoelectron spectroscopy (XPS) show the formation of boron nitride coating. The TGA curves indicate that the oxidation resistance of the PyC particles is improved by incorporating BN coating on the surface. The mass of the BN-coated PyC particles remains over 60% at 1200 °C whereas the PyC particles are oxidized completely at 920 °C. The investigation of microwave absorbing property reveals that compared with the PyC particles, the BN-coated PyC particles have lower permittivity (?', ??) and better absorbing property. The BN-coated PyC particles show a strong absorbing peak at 10.64 GHz, where the lowest reflectivity -21.72 dB is reached. And the reflectivity less than -10 dB is over the range of 9.6-12 GHz.

  1. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  2. Carbon black\\/silicone rubber blends as absorbing materials to reduce Electro Magnetic Interferences (EMI)

    Microsoft Academic Search

    Anna A. Barba; Gaetano Lamberti; Matteo d’Amore; Domenico Acierno

    2006-01-01

    Summary  In this work the microwave absorbing properties of carbon black\\/silicone rubber blends were investigated in the frequency\\u000a range 0.26.0 GHz, varying the carbon black contents. In particular, the permittivity of the samples was measured by a network\\u000a analyzer and then the experimental data were fitted as function of microwave frequency and carbon black content, ?*=?*(f,C).\\u000a \\u000a The reflection loss for a layer

  3. Two-photon or higher-order absorbing optical materials and methods of use

    NASA Technical Reports Server (NTRS)

    Marder, Seth (Inventor); Perry, Joseph (Inventor)

    2001-01-01

    Compositions capable of simultaneous two-photon absorption and higher order absorptivities are disclosed. Many of these compositions are compounds satisfying the formulae D-.PI.-D, A-.PI.-A, D-A-D and A-D-A, wherein D is an electron donor group, A is an electron acceptor group and .PI. comprises a bridge of .pi.-conjugated bonds connecting the electron donor groups and electron acceptor groups. In A-D-A and D-A-D compounds, the .pi. bridge is substituted with electron donor groups and electron acceptor groups, respectively. Also disclosed are methods that generate an electronically excited state of a compound, including those satisfying one of these formulae. The electronically excited state is achieved in a method that includes irradiating the compound with light. Then, the compound is converted to a multi-photon electronically excited state upon simultaneous absorption of at least two photons of light. The sum of the energies of all of the absorbed photons is greater than or equal to the transition energy from a ground state of the compound to the multi-photon excited state. The energy of each absorbed photon is less than the transition energy between the ground state and the lowest single-photon excited state of the compound is less than the transition energy between the multi-photon excited state and the ground state.

  4. Development of High Band Gap Absorber and Buffer Materials for Thin Film Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Dwyer, Dan

    2011-12-01

    CuInGaSe2 (CIGS) device efficiencies are the highest of the thin film absorber materials (vs. CdTe, alpha-Si, CuInSe2). However, the band gap of the highest efficiency CIGS cells deviates from the expected ideal value predicted by models [1]. Widening the band gap to the theoretically ideal value is one way to increase cell efficiencies. Widening the band gap can be accomplished in two ways; by finding a solution to the Ga-related defects which limit the open circuit voltage at high Ga ratios, or by utilizing different elemental combinations to form an alternative high band gap photoactive Cu-chalcopyrite (which includes any combination of the cations Cu, Al, Ga, and In along with the anions S, Se, and Te). This thesis focuses on the second option, substituting aluminum for gallium in the chalcopyrite lattice to form a CuInAlSe2 (CIAS) film using a sputtering and selenization approach. Both sequential and co-sputtering of metal precursors is performed. Indium was found to be very mobile during both sputtering processes, with a tendency to diffuse to the film surface even when deposited as the base layer in a sequential sputtering process. Elemental diffusion was controlled to a degree using thicker Cu top layer in co-sputtering. The greater thermal conductivity of stainless steel foil (16 W/mK) vs. glass (0.9-1.3 W/mK) can also be used to limit indium diffusion, by keeping the substrate cooler during sputtering. In both sputtering methods aluminum is deposited oxygen-free by capping the film with a Cu capping layer in combination with controlling the indium diffusion. Selenization of metal precursor films is completed using two different techniques. The first is a thermal evaporation approach from a heated box source (method 1 -- reactive thermal evaporation (RTE-Se)). The second is batch selenization using a heated tube furnace (method 2 -- batch selenization). Some batch selenized precursors were capped with ˜ 1mum of selenium. In both selenization methods elemental selenium is used at the selenium source. In method 1 films selenized above 500°C showed low Al incorporation and phase separation. Films selenized with a Se depositional rate of 12 A/s showed poor adhesion compared to samples selenized at 4 A/s. Segregation of aluminum towards the back contact as well as oxygen incorporation appears to cause adhesion loss in extreme cases, and poor interface electrical characteristics in others. The maximum device efficiency measured for method 1 was 5.2% under AM1.5 for a device with ˜ 2 at. % aluminum. For method 2, samples deposited on glass demonstrated poor adhesion and similar attributes to the RTE-Se samples. No improvements were seen with the additional Se capping layer on the film. Metal foil samples show improved adhesion vs. glass samples deposited under the same conditions. Samples still showed oxidation of aluminum at the Mo interface. Increasing the temperature to 550°C resulted in the loss of Mo adhesion due to excessive MoSe 2 formation. Samples selenized for 90 minutes at 520°C showed decreased adhesion compared to those selenized for 40 minutes. Again excess MoSe 2 growth was seen, though not to the extent of the samples selenized at 550°C. The effective heat of formation model suggests the low Al incorporation found in all films is due the favorable formation of InSe vs. In2Se3. It predicts InSe will form first at the growing film interface, and this phase is then consumed in the formation of CuInSe2 at temperatures above 220°C. This results in the consumption of In before the (Al,In)2Se 3 phase can form, and therefore minimal formation of the CuInAlSe 2 chalcopyrite phase. Due to minimal (Al,In)2Se3 formation, free Al is able to react with H2O or form Al2Se 3 which is also able to react with H2O. Both reactions result in the formation of Al2O3 and H2Se. This Al2O3 forms a resistive barrier at the back contact, which results in loss of adhesion in high Al films, and an I-V "roll-over" effect in low Al devices. In addition to CIAS studies, a study of alternative buffer layers to chemical b

  5. Quantitation of absorbed or deposited materials on a substrate that measures energy deposition

    DOEpatents

    Grant, Patrick G.; Bakajin, Olgica; Vogel, John S.; Bench, Graham

    2005-01-18

    This invention provides a system and method for measuring an energy differential that correlates to quantitative measurement of an amount mass of an applied localized material. Such a system and method remains compatible with other methods of analysis, such as, for example, quantitating the elemental or isotopic content, identifying the material, or using the material in biochemical analysis.

  6. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    John H. Bradford; Stephen Holbrook; Scott B. Smithson

    2004-12-09

    The focus of this project is direct detection of DNAPL's specifically chlorinated solvents, via material property estimation from multi-fold surface ground-penetrating radar (GPR) data. We combine state-of-the-art GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects.

  7. Two-photon or higher-order absorbing optical materials for generation of reactive species

    NASA Technical Reports Server (NTRS)

    Cumpston, Brian (Inventor); Lipson, Matthew (Inventor); Marder, Seth R. (Inventor); Perry, Joseph W. (Inventor)

    2003-01-01

    Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

  8. Two-photon or higher-order absorbing optical materials for generation of reactive species

    NASA Technical Reports Server (NTRS)

    Cumpston, Brian (Inventor); Lipson, Matthew (Inventor); Marder, Seth R (Inventor); Perry, Joseph W (Inventor)

    2007-01-01

    Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

  9. Plasmonic materials based on ZnO films and their potential for developing broadband middle-infrared absorbers

    NASA Astrophysics Data System (ADS)

    Kesim, Yunus E.; Battal, Enes; Okyay, Ali K.

    2014-07-01

    Noble metals such as gold and silver have been extensively used for plasmonic applications due to their ability to support plasmons, yet they suffer from high intrinsic losses. Alternative plasmonic materials that offer low loss and tunability are desired for a new generation of efficient and agile devices. In this paper, atomic layer deposition (ALD) grown ZnO is investigated as a candidate material for plasmonic applications. Optical constants of ZnO are investigated along with figures of merit pertaining to plasmonic waveguides. We show that ZnO can alleviate the trade-off between propagation length and mode confinement width owing to tunable dielectric properties. In order to demonstrate plasmonic resonances, we simulate a grating structure and computationally demonstrate an ultra-wide-band (4-15 ?m) infrared absorber.

  10. Plasmonic materials based on ZnO films and their potential for developing broadband middle-infrared absorbers

    SciTech Connect

    Kesim, Yunus E., E-mail: yunus.kesim@bilkent.edu.tr; Battal, Enes [Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800 (Turkey); UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800 (Turkey); Okyay, Ali K. [Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800 (Turkey); UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800 (Turkey)

    2014-07-15

    Noble metals such as gold and silver have been extensively used for plasmonic applications due to their ability to support plasmons, yet they suffer from high intrinsic losses. Alternative plasmonic materials that offer low loss and tunability are desired for a new generation of efficient and agile devices. In this paper, atomic layer deposition (ALD) grown ZnO is investigated as a candidate material for plasmonic applications. Optical constants of ZnO are investigated along with figures of merit pertaining to plasmonic waveguides. We show that ZnO can alleviate the trade-off between propagation length and mode confinement width owing to tunable dielectric properties. In order to demonstrate plasmonic resonances, we simulate a grating structure and computationally demonstrate an ultra-wide-band (4–15 ?m) infrared absorber.

  11. Canyon transfer neutron absorber to fissile material ratio analysis. Revision 1

    SciTech Connect

    Clemmons, J.S.

    1994-03-04

    Waste tank fissile material and non-fissile material estimates are used to evaluate criticality safety for the existing sludge inventory and batches of sludge sent to Extended Sludge Processing (ESP). This report documents the weight ratios of several non-fissile waste constituents to fissile waste constituents from canyon reprocessing waste streams. Weight ratios of Fe, Mn, Al, Mi, and U-238 to fissile material are calculated from monthly loss estimates from the F and H Canyon Low Heat Waste (LHW) and High Heat Waste (HHW) streams. The monthly weight ratios for Fe, Mn and U-238 are then compared to calculated minimum safe weight ratios. Documented minimum safe weight ratios for Al and Ni to fissile material are currently not available. Total mass data for the subject sludge constituents is provided along with scatter plots of the monthly weight ratios for each waste stream.

  12. Comparison of amorphous silicon absorber materials: Light-induced degradation and solar cell efficiency

    NASA Astrophysics Data System (ADS)

    Stuckelberger, M.; Despeisse, M.; Bugnon, G.; Schüttauf, J.-W.; Haug, F.-J.; Ballif, C.

    2013-10-01

    Several amorphous silicon (a-Si:H) deposition conditions have been reported to produce films that degrade least under light soaking when incorporated into a-Si:H solar cells. However, a systematic comparison of these a-Si:H materials has never been presented. In the present study, different plasma-enhanced chemical vapor deposition conditions, yielding standard low-pressure VHF a-Si:H, protocrystalline, polymorphous, and high-pressure RF a-Si:H materials, are compared with respect to their optical properties and their behavior when incorporated into single-junction solar cells. A wide deposition parameter space has been explored in the same deposition system varying hydrogen dilution, deposition pressure, temperature, frequency, and power. From the physics of layer growth, to layer properties, to solar cell performance and light-induced degradation, a consistent picture of a-Si:H materials that are currently used for a-Si:H solar cells emerges. The applications of these materials in single-junction, tandem, and triple-junction solar cells are discussed, as well as their deposition compatibility with rough substrates, taking into account aspects of voltage, current, and charge collection. In sum, this contributes to answering the question, "Which material is best for which type of solar cell?"

  13. A summary of measurements of permittivities and permeabilities of some microwave absorbing materials

    NASA Astrophysics Data System (ADS)

    Spurgeon, W. A.; Elrayess, M.; Dorsey, P.; Vittoria, C.

    1990-05-01

    This report presents results of measurements of permittivities and permeabilities of assorted materials collected by the U.S. Army Office of Low Observables Technology and Applications (LOTA), and by the U.S. Army Materials Technology Laboratory (MTL). The samples fell into the following categories: (1) Pure materials (Teflon, plexiglasses and casting plastic); (2) Metal-coated microspheres; (3) Carbospheres, both uncoated and metal coated; (4) Ferrites; (5) Magnetic metal flake; (6) Ceramic matrix composites; and (7) A standard paint. The data and its limitations and plans for additional testing are presented in the text. The most interesting results were obtained for a Rockwell Ferrite and for a 50/50 ferronickel flake which showed magnetic loss from 2 to 18 GHz.

  14. Hydrogen Absorbing Materials for Use as Radiation Shielding During Extended Space Flight Missions

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Minimizing radiation exposure from the galactic cosmic ray (GCR) environment during extended space missions is particularly crucial to crew health and safety. Here, an ideal candidate for shielding would be pure solid or liquid hydrogen, a material that effectively fragments heavy ions into ones of lower mass and energy that are more easily attenuated. Unfortunately, utilizing pure hydrogen is not presently feasible. It is, however, known that the hydrogen content of other materials (for example, metal hydrides, palladium alloys, and organic compounds) can exceed that of pure solid hydrogen and thus merit consideration as shielding candidates. This presentation will discuss an ongoing effort to develop novel shielding from such materials in concert with a coordinated testing/evaluation and modeling effort.

  15. Design of energy absorbing materials and composite structures based on porous shape memory alloys (SE)

    Microsoft Academic Search

    Ying Zhao

    2006-01-01

    Recently, attention has been paid to porous shape memory alloys. This is because the alloys show large and recoverable deformation, i.e. superelasticity and shape memory effect. Due to their light weight and potential large deformations, porous shape memory alloys have been considered as excellent candidates for energy absorption materials. In the present study, porous NiTi alloy with several different porosities

  16. Design and Analysis of Wideband Antenna with Application to Ground Penetrating Radar System

    Microsoft Academic Search

    G. E. Atteia; K. F. A. Hussein; A. A. Shaalan

    2007-01-01

    In this paper, a wide band antenna is proposed for ground-penetrating radar (GPR) system. This antenna consists of dipole antenna housed in a rectangular conducting reflector whose inner walls are coated by an absorbing material. The coating is composed of a number of layers with a conductivity profile designed to achieve the minimum voltage standing wave ratio (VSWR) of the

  17. 1998 SPIE Smart Structures and Materials Conf. Paper #332919/332742 High bandwidth tunability in a smart vibration absorber

    E-print Network

    Flatau, Alison B.

    in a smart vibration absorber Alison B. Flatau, + Marcelo J. Dapino ++ and Frederick T. Calkins Terfenol­D vibration absorber is developed in this paper. An overview of magnetostriction including to achieve high bandwidth tunability in the performance of a Terfenol­D vibration absorber. Keywords

  18. Analysis of SnS2 hyperdoped with V proposed as efficient absorber material.

    PubMed

    Seminovski, Yohanna; Palacios, Pablo; Wahnón, Perla

    2014-10-01

    Intermediate-band materials can improve the photovoltaic efficiency of solar cells through the absorption of two subband-gap photons that allow extra electron-hole pair formations. Previous theoretical and experimental findings support the proposal that the layered SnS2 compound, with a band-gap of around 2 eV, is a candidate for an intermediate-band material when it is doped with a specific transition-metal. In this work we characterize vanadium doped SnS2 using density functional theory at the dilution level experimentally found and including a dispersion correction combined with the site-occupancy-disorder method. In order to analyze the electronic characteristics that depend on geometry, two SnS2 polytypes partially substituted with vanadium in symmetry-adapted non-equivalent configurations were studied. In addition the magnetic configurations of vanadium in a SnS2 2H-polytype and its comparison with a 4H-polytype were also characterized. We demonstrate that a narrow intermediate-band is formed, when these dopant atoms are located in different layers. Our theoretical predictions confirm the recent experimental findings in which a paramagnetic intermediate-band material in a SnS2 2H-polytype with 10% vanadium concentration is obtained. PMID:25204457

  19. Nanosized Ce-Zn substituted microwave absorber material for X-band applications

    NASA Astrophysics Data System (ADS)

    Sadiq, Imran; Ali, Irshad; Rebrov, Evgeny; Naseem, Shahzad; Ashiq, M. Naeem; Rana, M. U.

    2014-12-01

    The sol-gel autocombustion method has been used to synthesize the Ce-Zn substituted with composition Sr2-xCexNi2Fe28-yZnyO46 (x=0.02, 0.04, 0.06, 0.08, 0.010 and y=0.1, 0.2, 0.3, 0.4, 0.5) X-type hexagonal ferrites. The XRD analysis confirms the single phase of the material. The variation in lattice parameters can be observed with addition of Ce-Zn dopant. The ferrites substituted with Ce-Zn contents have low value of grain size than the unsubstituted ferrites. The crystallite size measured from TEM and HRTEM analysis was found in the range of 40-45 nm which is in good agreement with the theoretically measured by Scherer formula. The room temperature electrical resistivity lies in the range of ~109 ?-cm, so the investigated sample can be considered good material for reducing the eddy current losses. The enhancement in magnetic properties (saturation magnetization, retentivity and coercivity) has been observed with the substitution of Ce-Zn contents in pure ferrites. The increment in resistivity and magnetic properties with the substitution of Ce-Zn dopant makes it important candidate to be used in the formation of multilayer chip inductors (MLCIs). The maximum reflection loss of -23.4 dB at 12.858 GHz is obtained by Ce-Zn doped ferrites and attenuation constant agrees well with the reflection loss. The microwave absorption properties of this substituted material reflect its applications in super high frequency (SHF) devices.

  20. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    SciTech Connect

    Aguiar, Vitor A. P.; Medina, Nilberto H. [Instituto de Fisica, Universidade de Sao Paulo, SP (Brazil); Moreira, Ramon H.; Silveira, Marcilei A. G. [Departamento de Fisica, Centro Universitario da FEI, Sao Bernardo do Campo, SP (Brazil)

    2010-05-21

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely {sup 40}K, {sup 232}Th and {sup 238}U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  1. Quantum storage of polarization qubits in birefringent and anisotropically absorbing materials

    E-print Network

    Christoph Clausen; Felix Bussieres; Mikael Afzelius; Nicolas Gisin

    2012-02-24

    Storage of quantum information encoded into true single photons is an essential constituent of long-distance quantum communication based on quantum repeaters and of optical quantum information processing. The storage of photonic polarization qubits is, however, complicated by the fact that many materials are birefringent and have polarization-dependent absorption. Here we present and demonstrate a simple scheme that allows compensating for these polarization effects. The scheme is demonstrated using a solid-state quantum memory implemented with an ensemble of rare-earth ions doped into a biaxial yttrium orthosilicate ($Y_2SiO_5$) crystal. Heralded single photons generated from a filtered spontaneous parametric downconversion source are stored, and quantum state tomography of the retrieved polarization state reveals an average fidelity of $97.5 \\pm 0.4%$, which is significantly higher than what is achievable with a measure-and-prepare strategy.

  2. Multiple-layer Radiation Absorber

    NASA Astrophysics Data System (ADS)

    Baker, Robert M. L.; Baker, Bonnie Sue

    A structure is discussed for absorbing incident radiation, either electromagnetic (EM) or sound. Such a surface structure is needed, for example, in a highly sensitive high-frequency gravitational wave or HFGW detector such as the Li-Baker. The multi-layer absorber, which is discussed, is constructed with metamaterial [MM] layer or layers on top. This MM is configured for a specific EM or sound radiation frequency band, which absorbs incident EM or sound radiation without reflection. Below these top MM layers is a substrate of conventional EM-radiation absorbing or acoustical absorbing reflective material, such as an array of pyramidal foam absorbers. Incident radiation is partially absorbed by the MM layer or layers, and then it is more absorbed by the lower absorbing and reflecting substrate. The remaining reflected radiation is even further absorbed by the MM layers on its "way out_ so that essentially all of the incident radiation is absorbed _ a nearly perfect black-body absorber. In a HFGW detector a substrate, such as foam absorbers, may outgas into a high vacuum and reduce the capability of the vacuum-producing equipment, however, the layers above this lowest substrate will seal the absorbing and reflecting substrate from any external vacuum. The layers also serve to seal the absorbing material against air or water flow past the surfaces of aircraft, watercraft or submarines. Other applications for such a multiple-level radiation absorber include stealth aircraft, missiles and submarines.

  3. Polypyrrole Based Microwave Absorbers

    Microsoft Academic Search

    V.-T. Truong; S. Z. Riddell; R. F. Muscat

    1998-01-01

    Reflection of microwave radiations from single layer and two-layer materials is calculated. Microwave absorbing materials are formulated by mixing a commercially available paint or rubber with the conducting polypyrrole (PPy) powder. The reflection loss strongly depends on thickness and complex permittivity of the material. For a single layer material, optimum values of the real part, ?', and imaginary part, ?'',

  4. Comparison of three measurement techniques for the normal absorption coefficient of sound absorbing materials in the free field.

    PubMed

    Hirosawa, Kunikazu; Takashima, Kazuhiro; Nakagawa, Hiroshi; Kon, Makoto; Yamamoto, Aki; Lauriks, Walter

    2009-12-01

    Three different techniques for evaluating the absorption coefficient of sound absorbing materials in free field conditions are discussed. One technique measures the acoustic impedance at one point nearby a specimen, the other two techniques evaluate the impedance from the transfer function of two sound pressures and two particle velocities at two points. These are called "PU-method," "PP-method," and "UU-method," respectively. An iterative algorithm to estimate the acoustic impedance of the locally reactive specimen in the spherical wave field is also applied. First, the effect of receiver positions, specimen areas, and source heights to the measured normal absorption coefficient is investigated by the boundary element method. According to these investigations, the PU-method is most stable against the effect of specimen area, and the UU-method is easily affected by that effect. Closer source to the specimen distance is advantageous for the signal to noise ratio of these measurement techniques, but correction for the effect of the spherical wave field has to be applied. As a finding, the iterative algorithm works for all of three techniques. Finally, the PU-method is applied experimentally with a pressure-velocity sensor and a loudspeaker in a hemi-anechoic room. As a result, the calculated results have been verified. PMID:20000915

  5. Distribution of absorbed doses in the materials irradiated by ''RHODOTRON'' electron accelerator: Experiment and Monte Carlo simulations

    SciTech Connect

    Oleg E. Krivosheev et al.

    2001-07-02

    This paper describes the experimental setup and presents studies of absorbed doses in different metals and dielectrics along with corresponding Monte Carlo energy deposition simulations. Experiments were conducted using a 5 MeV electron accelerator. We used several Monte Carlo code systems, namely MARS, MCNP, and GEANT to simulate the absorbed doses under the same conditions as in experiment. We compare calculated and measured high and low absorbed doses (from few kGy to hundreds kGy) and discuss the applicability of these computer codes for applied accelerator dosimetry.

  6. Shock absorber

    Microsoft Academic Search

    G. F. Kalb; D. M. Brown

    1987-01-01

    A shock absorber is described for a wireline instrument for use in a liquid containing well to reduce sock if the instrument impacts on an object while being lowered, the shock absorber comprising: a sleeve, having an inner surface; a mandrel, telescopically movable within the sleeve from an outward extended position to an inward retracted position if a sufficient impact

  7. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  8. Light scattering by dust particles (PROGRA2 experiment): size and structure effects for transparent and absorbing materials

    NASA Astrophysics Data System (ADS)

    Hadamcik, E.; Renard, J.-B.; Lasue, J.; Levasseur-Regourd, A. C.

    2007-08-01

    1- Introduction Cometary and possibly interplanetary dust particles seem to be mainly made of agglomerates of submicron and micron-sized grains. These particles are among the most primitive in our solar system. Regoliths on asteroidal and planetary surfaces seem to be loose materials produced by impinging meteorites on the surface of small bodies. Comparing their physical properties is thus fundamental to understand their evolution. To interpret remote observations of solar light scattered by dust particles and regoliths, it is necessary to use numerical and experimental simulations [1,2,3]. 2- PROGRA2 experiment PROGRA2 instruments are polarimeters; the light sources are two randomly polarized lasers (632.8 nm and 543.5 nm). Levitating particles (in microgravity or lifted by an air-draught) are studied by imaging polarimetry. Details on the instruments can be found in [4,5]. 3- Samples Two kinds of samples are studied: compact particles in the (1-400) micrometer size range and fluffy aggregates in the same size range, made from submicron and micronsized grains. The materials are transparent silica and absorbing carbon. Some deposited particles are huge agglomerates of micron-sized grains produced by random ballistic deposition of single grains [6,7] or produced by evaporation of mixtures in alcohol of fluffy aggregates of submicron-sized grains. Two samples are made of silica spheres coated by a carbonaceous black compound. Cometary analogues are mixtures of silica and amorphous carbon or Mg-Fe silicates mixed with amorphous carbon. 4- Results Phase curves and their main parameters (negative polarization at small phase angles and maximum polarization, Pmax, at 90-100° phase angle) for the different materials will be compared and related to the physical properties. For example, it is well known by numerical simulations and/or by experiments that the maximum polarization decreases when the size (submicrometer range) of the grains increases [2,8,9]. An inverse rule is found for compact grains, larger than the wavelength. Mixtures of fluffy silica and fined grained amorphous carbon or better Mg-Fe silicates with amorphous carbon are excellent cometary particles analogues (as light scattering is concerned) if they are mixed with some compact micron-sized grains [9]. Nevertheless the structure of the aggregates seems to play a major role to obtain the negative branch found on the polarimetric phase curves for comets [10]. 5- Discussion and conclusions The experiments purpose is to help to disentangle the different physical properties of dust particles that can be deduced from remote observations (cometary dust, regoliths). Differences between the main parameters influencing the variations of Pmax and the presence of a negative branch on the polarimetric phase curves for lifted and deposited particles (in huge agglomerates or not) will be discussed. Acknowledgments: Technische Universität Carolo-Wilhelmina, Braunschweig, Deutschland (Pr Blum, Dr Schräpler); University of New Mexico, Albuquerque, USA (Pr Rietmeijer); NASA Goddard Space Flight Center, Maryland, USA (Dr Nuth) References [1] A.C. Levasseur-Regourd, E. Hadamcik, JQSRT 79-80, 903 (2003) [2] J. Lasue, A.C. Levasseur-Regourd, JQSRT 100, 220 (2006) [3] J.-B. Renard et al., ASR 31, 2511 (2003) [4] J.-B. Renard et al., Appl. Opt. 91, 609 (2002) [5] E. Hadamcik et al., JQSRT 106, 74 (2007) [6] J. Blum, R. Schreapler, Phys. Rev Let 93:115031 (2004) [7] J. Blum et al., Astrophys J 652, 1768 (2006) [8] R. West, Appl. Opt. 30, 5216 (1991) [9] E. Hadamcik et al., JQSRT 100, 143 (2006) [10] E. Hadamcik et al., Icarus, in press (2007)

  9. Combining linear polarization spectroscopy and the Representative Layer Theory to measure the Beer-Lambert law absorbance of highly scattering materials.

    PubMed

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2015-01-01

    Visible and Near Infrared (Vis-NIR) Spectroscopy is a powerful non destructive analytical method used to analyze major compounds in bulk materials and products and requiring no sample preparation. It is widely used in routine analysis and also in-line in industries, in-vivo with biomedical applications or in-field for agricultural and environmental applications. However, highly scattering samples subvert Beer-Lambert law's linear relationship between spectral absorbance and the concentrations. Instead of spectral pre-processing, which is commonly used by Vis-NIR spectroscopists to mitigate the scattering effect, we put forward an optical method, based on Polarized Light Spectroscopy to improve the absorbance signal measurement on highly scattering samples. This method selects part of the signal which is less impacted by scattering. The resulted signal is combined in the Absorption/Remission function defined in Dahm's Representative Layer Theory to compute an absorbance signal fulfilling Beer-Lambert's law, i.e. being linearly related to concentration of the chemicals composing the sample. The underpinning theories have been experimentally evaluated on scattering samples in liquid form and in powdered form. The method produced more accurate spectra and the Pearson's coefficient assessing the linearity between the absorbance spectra and the concentration of the added dye improved from 0.94 to 0.99 for liquid samples and 0.84-0.97 for powdered samples. PMID:25467494

  10. A broad-line NMR investigation of water absorbed by cured epoxy resin graphite-fiber composite materials

    Microsoft Academic Search

    Fuller

    1980-01-01

    The effect of water absorption on the mechanical properties of epoxy resin-graphite fiber composites was investigated. Data collected from nuclear magnetic resonance spectra were used to determine three things: (1) the state of the water in the bulk resin and how tightly the water is bound (2) if the water in the composite is being absorbed primarily in the matrix

  11. Tungsten-aluminum brazed material application on to the internal target or radiation absorber in electron storage rings

    Microsoft Academic Search

    T Momose; K Nishida; H Hirayama; T Toga; H Ishimaru

    1996-01-01

    The requirement for radiation absorbers electron storage rings must contain anticorrosion characteristics at the water\\/metal boundary under synchrotron irradation. To reduce the corrosion, radiation dose can be decreased by increasing the thickness. This increases temperature difference and therefore deteriorates its thermal duarability. Tungsten (W) and molybdenum (Mo) have high melting point and short absorption length but are weak at a

  12. Radar Entomology

    NSDL National Science Digital Library

    0000-00-00

    Radar tracking used to profile insect migration, mating and flight patterns. Many links to various pages include current workers in radar entomology, historical uses of the technology, and many images.

  13. Dependence of Yb-169 absorbed dose energy correction factors on self-attenuation in source material and photon buildup in water

    SciTech Connect

    Medich, David C.; Munro, John J. III [Radiation Laboratory, University of Massachusetts Lowell, 1 University Avenue, Lowell, Massachusetts 01854 (United States); Source Production and Equipment Co., Inc., 113 Teal Street, St. Rose, Louisiana 70087 (United States)

    2010-05-15

    Purpose: Absorbed dose energy correction factors, used to convert the absorbed dose deposited in a LiF thermoluminescent dosimeter (TLD) into the clinically relevant absorbed dose to water, were obtained for both spherical volumetric sources and for the model 4140 HDR Yb-169 source. These correction factors have a strong energy dependence below 200 keV; therefore, spectral changes were quantified as Yb-169 photons traveled through both source material (Yb{sub 2}O{sub 3}) and water with the corresponding absorbed dose energy correction factors, f(r,{theta}), calculated as a function of location in a phantom. Methods: Using the MCNP5 Monte Carlo radiation transport simulation program, the Yb-169 spectrum emerging from spherical Yb{sub 2}O{sub 3} sources (density 6.9 g/cm{sup 3}) with radii between 0.2 and 0.9 mm were analyzed and their behavior compared against those for a point-source. The absorbed dose deposited to both LiF and H{sub 2}O materials was analyzed at phantom depths of 0.1-10 cm for each source radius and the absorbed dose energy correction factor calculated as the ratio of the absorbed dose to water to that of LiF. Absorbed dose energy correction factors for the Model 4140 Yb-169 HDR brachytherapy source similarly were obtained and compared against those calculated for the Model M-19 Ir-192 HDR source. Results: The Yb-169 average spectral energy, emerging from Yb{sub 2}O{sub 3} spherical sources 0.2-0.9 mm in radius, was observed to harden from 7% to 29%; as these photons traveled through the water phantom, the photon average energy softened by as much as 28% at a depth of 10 cm. Spectral softening was dependent on the measurement depth in the phantom. Energy correction factors were found to vary both as a function of source radius and phantom depth by as much as 10% for spherical Yb{sub 2}O{sub 3} sources. The Model 4140 Yb-169 energy correction factors depended on both phantom depth and reference angle and were found to vary by more than 10% between depths of 1 and 10 cm and angles of 0 deg. and 180 deg. This was in contrast to that of the Model M-19 Ir-192 source which exhibited approximately 3.5%-4.4% variation in its energy correction factors from phantom depths of 0.5-10 cm. The absorbed dose energy correction factor for the Ir-192 source, on the other hand, was independent of angle to within 1%. Conclusions: The application of a single energy correction factor for Yb-169 TLD based dosimetry would introduce a high degree of measurement uncertainty that may not be reasonable for the clinical characterization of a brachytherapy source; rather, an absorbed dose energy correction function will need to be developed for these sources. This correction function should be specific to each source model, type of TLD used, and to the experimental setup to obtain accurate and precise dosimetric measurements.

  14. Radar principles

    NASA Technical Reports Server (NTRS)

    Sato, Toru

    1989-01-01

    Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

  15. Investigation of transmitted, reflected, and absorbed powers of periodic and aperiodic multilayered structures composed of bi-anisotropic metamaterial slab and conventional material

    NASA Astrophysics Data System (ADS)

    Hasar, Ugur Cem; Barroso, Joaquim José; Kaya, Yunus; Karacali, Tehvit; Ertugrul, Mehmet

    2015-01-01

    In this study, we investigate transmitted, reflected, and absorbed powers in forward and backward directions of periodic and aperiodic multilayered structures composed of bi-anisotropic metamaterial (MM) slab and conventional material. Aperiodic multilayered structure is realized by a change in thickness of any bi-anisotropic MM slab or of any conventional material. From this analysis, we note the following key results. First, identical (non-identical) forward and backward transmitted (reflected and absorbed) powers are observed for the analyzed periodic and aperiodic multilayered structures due to reciprocity (reflection-asymmetry) of bi-anisotropic MM slabs. Second, thickness-resonance phenomenon of conventional materials produces some peaks in the transmitted powers of periodic multilayered structures aside from the resonance frequency region of bi-anisotropic MM slabs. Third, each thickness-resonance frequency splits into many frequencies upon increasing the number of sections of periodic multilayered structures (no splitting when number of periods is one). Fourth, while the effect of changing the thickness of any bi-anisotropic MM slab within the aperiodic multilayered structure has no considerable effect around the resonance region of bi-anisotropic MM slabs (resonance of resonating structures such as MM slabs does not change with thickness), the same change in thickness of the conventional material drastically alters forward/backward reflected and absorbed powers aside from the resonance region of bi-anisotropic MM slabs (thickness-resonance totally depends on the value of thickness of conventional materials). The outcomes presented here can be particularly useful for propagation-related applications requiring cascade connection of various MM slabs.

  16. Potential of short Si–Ti–C–O fiber-reinforced epoxy matrix composite as electromagnetic wave absorbing material

    Microsoft Academic Search

    Y. Kagawa; K. Matsumura; H. Iba; Y. Imahashi

    2007-01-01

    The effects of fiber electrical properties on electromagnetic wave absorbing potential in short Si–Ti–C–O fiber-dispersed\\u000a epoxy matrix composites were studied. Six kinds of short Si–Ti–C–O fibers with different respective electrical resistivity\\u000a were incorporated into an epoxy matrix and the dielectric properties of the composites in a frequency range from 1 MHz to\\u000a 1 GHz were measured. The penetration depth of electromagnetic wave,

  17. Design and realization of one-dimensional double hetero-structure photonic crystals for infrared-radar stealth-compatible materials applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhixun; Cheng, Yongzhi; Nie, Yan; Wang, Xian; Gong, Rongzhou

    2014-08-01

    In this paper, a new type one-dimensional (1D) double hetero-structure composite photonic crystal (CPC) for infrared-radar stealth-compatible materials applications was proposed and studied numerically and experimentally. First, based on transfer matrix method of thin-film optical theory, the propagation characteristics of the proposed structure comprising a stack of different alternating micrometer-thick layers of germanium and zinc sulfide were investigated numerically. Calculation results exhibit that this 1D single hetero-structure PC could achieve a flat high reflectivity gradually with increasing the number of the alternating media layers in a single broadband range. Then, based on principles of distributed Bragg reflector micro-cavity, a 1D double hetero-structure CPC comprising four PCs with thickness of 0.797 ?m, 0.592 ?m, 1.480 ?m, and 2.114 ?m, respectively, was proposed. Calculation results exhibit that this CPC could achieve a high reflectance of greater than 0.99 in the wavelength ranges of 3-5 ?m and 8-14 ?m and agreed well with experiment. Further experiments exhibit that the infrared emissivity of the proposed CPC is as low as 0.073 and 0.042 in the wavelength ranges of 3-5 ?m and 8-12 ?m, respectively. In addition, the proposed CPC can be used to construct infrared-radar stealth-compatible materials due to its high transmittance in radar wave band.

  18. Design and realization of one-dimensional double hetero-structure photonic crystals for infrared-radar stealth-compatible materials applications

    SciTech Connect

    Wang, Zhixun; Cheng, Yongzhi, E-mail: cyz0715@126.com; Nie, Yan; Wang, Xian; Gong, Rongzhou, E-mail: rzhgong@mail.hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-07

    In this paper, a new type one-dimensional (1D) double hetero-structure composite photonic crystal (CPC) for infrared-radar stealth-compatible materials applications was proposed and studied numerically and experimentally. First, based on transfer matrix method of thin-film optical theory, the propagation characteristics of the proposed structure comprising a stack of different alternating micrometer-thick layers of germanium and zinc sulfide were investigated numerically. Calculation results exhibit that this 1D single hetero-structure PC could achieve a flat high reflectivity gradually with increasing the number of the alternating media layers in a single broadband range. Then, based on principles of distributed Bragg reflector micro-cavity, a 1D double hetero-structure CPC comprising four PCs with thickness of 0.797??m, 0.592??m, 1.480??m, and 2.114??m, respectively, was proposed. Calculation results exhibit that this CPC could achieve a high reflectance of greater than 0.99 in the wavelength ranges of 3–5??m and 8–14??m and agreed well with experiment. Further experiments exhibit that the infrared emissivity of the proposed CPC is as low as 0.073 and 0.042 in the wavelength ranges of 3–5??m and 8–12??m, respectively. In addition, the proposed CPC can be used to construct infrared-radar stealth-compatible materials due to its high transmittance in radar wave band.

  19. Structural and electronic properties of CuSbS2 and CuBiS2: potential absorber materials for thin-film solar cells.

    PubMed

    Dufton, Jesse T R; Walsh, Aron; Panchmatia, Pooja M; Peter, Laurie M; Colombara, Diego; Islam, M Saiful

    2012-05-28

    As the demand for photovoltaics rapidly increases, there is a pressing need for the identification of new visible light absorbing materials for thin-film solar cells that offer similar performance to the current technologies based on CdTe and Cu(In,Ga)Se(2). Metal sulphides are the ideal candidate materials, but their band gaps are usually too large to absorb significant fractions of visible light. However, by combining Cu(+) (low binding energy d(10) band) and Sb(3+)/Bi(3+) (low binding energy s(2) band), the ternary sulphides CuSbS(2) and CuBiS(2) are formed, which have been gathering recent interest for solar cell applications. Using a hybrid density functional theory approach, we calculate the structural and electronic properties of these two materials. Our results highlight the stereochemical activity of the Sb and Bi lone pair electrons, and predict that the formation of hole carriers will occur in the Cu d(10) band and hence will involve oxidation of Cu(I). PMID:22514020

  20. Development of BaAlxFe12-xO19-NPR nanocomposite as an efficient absorbing material in the X-band

    NASA Astrophysics Data System (ADS)

    Ozah, S.; Bhattacharyya, N. S.

    2015-01-01

    An efficient BaAlxFe12-xO19- novolac phenolic resin (NPR) nanocomposite material is developed to use as absorbing material in the X band. The material developed has a hexagonal structure of nanosize aluminium substituted barium ferrite, as is confirmed by X-ray diffraction pattern studies. The average grain size of barium nanoparticles is found to be ~26 nm. Measurement of complex permittivity and complex permeability in the X-band indicates increase of the properties with increase in Al3+ ions in the ferrite. A measured absorption study has been carried out on absorber fabricated on a metal backing based on the transmission line theory. Substitution of Fe3+ with Al3+ is found to increase the absorption properties of barium ferrite. Reflection loss measurement of the samples shows an enhancement of absorption from -27.56 dB to -40.06 dB with the variation of Al3+ substitution, x=1.0-1.6 in the BaAlxFe12-xO19 in NPR matrix.

  1. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo, E-mail: guanjg@whut.edu.cn [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Zhai, Pengcheng [School of Science, Wuhan University of Technology, Wuhan 430070 (China)

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7?mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple ?/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  2. Effect of short carbon fibers and MWCNTs on microwave absorbing properties of polyester composites containing nickel-coated carbon fibers

    Microsoft Academic Search

    Igor Maria De Rosa; Adrian Dinescu; Fabrizio Sarasini; Maria Sabrina Sarto; Alessio Tamburrano

    2010-01-01

    Multiphase composite materials filled with multiwall carbon nanotubes (MWCNTs), short nickel-coated carbon fibers and millimeter-long carbon fibers with various weight fractions and compositions are developed and used for the design of wide-band thin radar-absorbing screens. The effective complex permittivity of several composite samples is measured in the frequency range from 8GHz to 18GHz. The obtained results show that the addition

  3. Radar background signal reduction study

    Microsoft Academic Search

    E. F. Knott; C. J. Ray; M. S. West; R. J. Wohlers

    1980-01-01

    This report summarizes a study whose objective was to identify materials and\\/or techniques to reduce radar background signals for ground plane radar cross section (RCS) ranges. Background signal reduction is essential for improving the accuracy of RCS measurements and the primary application is for operations at the RATSCAT range on the White Sands Missile Range in New Mexico. A survey

  4. Apollo couch energy absorbers

    NASA Technical Reports Server (NTRS)

    Wesselski, C. J.; Drexel, R. E.

    1972-01-01

    Load attenuators for the Apollo spacecraft crew couch and its potential applications are described. Energy absorption is achieved through friction and cyclic deformation of material. In one concept, energy absorption is accomplished by rolling a compressed ring of metal between two surfaces. In another concept, energy is absorbed by forcing a plastically deformed washer along a rod. Among the design problems that had to be solved were material selection, fatigue life, ring slippage, lubrication, and friction loading.

  5. Technical evaluation of Russian aircraft stealth coating and structural materials

    Microsoft Academic Search

    F. D. Gac; A. T. Jr. Young; A. Migliori

    1996-01-01

    Treating aircraft, missiles, and ships with materials that absorb electromagnetic energy continues to be an important technique for reducing a vehicle`s radar cross section (RCS) and improving tis combat effectiveness and survivability. Work at the Russian Scientific Center for Applied Problems in Electrodynamics (SCAPE) has produced and experimentally validated an accurate predictor of the interaction of electromagnetic radiation with discontinuous

  6. Theoretical and experimental study of the diffuse transmission of light through highly concentrated absorbing and scattering materials. Part I: Monte-Carlo simulations

    NASA Astrophysics Data System (ADS)

    Bressel, L.; Reich, O.

    2014-10-01

    In many technical materials and commercial products like sunscreen or paint high particle and absorber concentrations are present. An important parameter for slabs of these materials is the diffuse transmission of light, which quantifies the total amount of directly and diffusely transmitted light. Due to the high content of scattering particles not only multiple scattering but also additional dependent scattering occurs. Hence, simple analytical models cannot be applied to calculate the diffuse transmission. In this work a Monte-Carlo program for the calculation of the diffuse transmission of light through dispersions in slab-like geometry containing high concentrations of scattering particles and absorbers is presented and discussed in detail. Mie theory is applied for the calculation of the scattering properties of the samples. Additionally, dependent scattering is considered in two different models, the well-known hard sphere model in the Percus-Yevick approximation (HSPYA) and the Yukawa model in the Mean Spherical Approximation (YMSA). Comparative experiments will show the accurateness of the program as well as its applicability to real samples [1].

  7. Synthesis and characterisation of Copper Zinc Tin Sulphide (CZTS) compound for absorber material in solar-cells

    Microsoft Academic Search

    Vipul Kheraj; K. K. Patel; S. J. Patel

    2013-01-01

    The development of thin-film semiconductor compounds, such as Copper Indium Gallium Selenide (CIGS), has caused remarkable progress in the field of thin-film photovoltaics. However, the scarcity and the increasing prices of indium impose the hunt for alternative materials. The Copper Zinc Tin Sulphide (CZTS) is one of the promising emerging materials with Kesterite-type crystal structure and favourable material properties like

  8. The design of Maxwellian absorbers for numerical boundary conditions and for practical applications using engineered artificial materials

    Microsoft Academic Search

    R. W. Zislkowski

    1997-01-01

    A Maxwellian material interpretation of the Berenger (see J. Computat. Phys., vol.114, p.185-200, 1994) perfectly matched layer (PML) is developed using polarization and magnetization fields. The PML material is found to be a passive lossy electric and magnetic medium with particular conductivity and Debye dispersion characteristics. Although it is recognized that the PML medium is physically unrealizable, this polarization and

  9. CONTROLLABLE ABSORBING STRUCTURE OF METAMATERIAL AT MICROWAVE

    Microsoft Academic Search

    Zhanxian Xu; Weigan Lin; Lidu Kong

    2007-01-01

    Akind of controllable metamaterial absorbing structure is presented in this paper, both transmission coefficient and single radar cross section (RCS) are electrically controlled. This structure is composed from split ring resonators (SRRs) and metallic wire arrays including pin diodes, pin diodes are periodically inserted at these wire arrays discontinuous, and they can be either in an on state or in

  10. Spaceborne radar

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Eckerman, J.; Meneghini, R.; Atlas, D.; Boerner, W. M.; Cherry, S.; Clark, J. F.; Doviak, R. J.; Goldhirsh, J.; Lhermitte, R. M.

    1981-01-01

    The spaceborne radar panel considered how radar could be used to measure precipitation from satellites. The emphasis was on how radar could be used with radiometry (at microwave, visible (VIS), and infrared (IR) wavelengths) to reduce the uncertainties of measuring precipitation with radiometry alone. In addition, the fundamental electromagnetic interactions involved in the measurements were discussed to determine the key work areas for research and development to produce effective instruments. Various approaches to implementing radar systems on satellites were considered for both shared and dedicated instruments. Finally, a research and development strategy was proposed for establishing the parametric relations and retrieval algorithms required for extracting precipitation information from the radar and associated radiometric data.

  11. Diffuse and coherent backscattering by discrete random media—I. Radar reflectivity, polarization ratios, and enhancement factors for a half-space of polydisperse, nonabsorbing and absorbing spherical particles

    Microsoft Academic Search

    Michael I. Mishchenko

    1996-01-01

    It has been demonstrated recently that diffuse, incoherent multiple scattering of electromagnetic waves by media composed of randomly positioned, discrete scattering particles is always accompanied by coherent backscattering and may explain intriguing opposition phenomena observed for some solar system bodies, in particular peculiar characteristics of radar returns from icy satellite surfaces. In this paper, we study theoretically photometric and polarization

  12. Mesoflowers: A new class of highly efficient surface-enhanced Raman active and infrared-absorbing materials

    Microsoft Academic Search

    Panikkanvalappil Ravindranathan Sajanlal; Thalappil Pradeep

    2009-01-01

    A method for the synthesis of a new class of anisotropic mesostructured gold material, which we call “mesoflowers”, is demonstrated.\\u000a The mesoflowers, unsymmetrical at the single particle level, resemble several natural objects and are made up of a large number\\u000a of stems with unusual pentagonal symmetry. The mesostructured material has a high degree of structural purity with star-shaped,\\u000a nano-structured stems.

  13. Measurement of absorbed doses near metal and dental material interfaces irradiated by X- and gamma-ray therapy beams

    Microsoft Academic Search

    M. Farahani; F. C. Eichmiller; W. L. McLaughlin

    1990-01-01

    Soft-tissue damage adjacent to dental restorations is a deleterious side effect of radiation therapy which is associated with low-energy electron scatter from dental materials of high electron density. This study was designed to investigate the enhancement of dose to soft tissue (or water) close to high electron-density materials and to measure the detailed lateral and depth-dose profiles in soft-tissue-simulating polymer

  14. Composite sandwich constructions for absorbing the electromagnetic waves

    Microsoft Academic Search

    Po Chul Kim; Dai Gil Lee

    2009-01-01

    RAS (radar absorbing structures) is a key component for weapon systems such as aircrafts, warships, and missiles to achieve both the stealth performance by absorbing EM (Electromagnetic) waves incident on and load bearing capability. In this work, the RAS was fabricated as sandwich constructions composed of nanocomposite, carbon fabric\\/epoxy composite, and PVC foam. The nanocomposite composed of E-glass fabric, epoxy

  15. Influence on the laser induced backside dry etching of thickness and material of the absorber, laser spot size and multipulse irradiation

    NASA Astrophysics Data System (ADS)

    Smausz, T.; Csizmadia, T.; Kresz, N.; Vass, Cs.; Márton, Zs.; Hopp, B.

    2007-12-01

    Laser induced backside dry etching method (LIBDE) was developed - analogously to the well-known laser induced backside wet etching (LIBWE) technique - for the micromachining of transparent materials. In this procedure, the absorbing liquid applied during LIBWE was replaced with solid metal layers. Fused silica plates were used as transparent targets. These were coated with 15-120 nm thick layers of different metals (silver, aluminium and copper). The absorbing films were irradiated by a nanosecond KrF excimer laser beam through the quartz plate. The applied fluence was varied in the 150-2000 mJ/cm 2 range, while the irradiated area was between 0.35 and 3.6 mm 2. At fluences above the threshold values, it was found that the metal layers were removed from the irradiated spots and the fused silica was etched at the same time. In our experiments, we investigated the dependence of the main parameters (etch rate and threshold) of LIBDE on the absorption of the different metal layers (silver, copper, aluminium), on the size of the irradiated area, on the film thickness and on the number of processing laser pulses.

  16. Spatial-spectral processing for imaging systems: Multibeam RF imaging and radar systems using spectral hole burning materials

    NASA Astrophysics Data System (ADS)

    Braker, Benjamin M.

    Systems which form many spatial beams (beamformers) for the RF and microwave spectral bands output either a few simultaneous spatial beams across a wide bandwidth---using true-time-delay beamformers---or many simultaneous spatial beams across a moderate bandwidth---using digital aperture synthesis imagers. The simultaneous spatial beams in true-time-delay beamformers require parallel hardware while digital aperture synthesis imagers requires both high speed digitizers and huge digital processors. Moreover; each output beam is typically processed further by a spectrum analyzer or a radar processor. Simultaneous formation and processing of all spatial beams is intractable for wide bandwidths and many beams. This dissertation develops and demonstrates a new class of photonic processing architectures which form and process many simultaneous, wide bandwidth spatial beams. These photonic architectures modulate RF signals from an emulated array of antennas onto an array of coherent optical carriers. I show the theory, the methods, and the results for systems which use Fourier optics and spectral hole burning (SHB) crystals; the demonstrated applications are: wideband RF imaging, Doppler radar, and multi-static radar applications. Proof-of-concept results show 20-beam RF images across a 1 GHz bandwidth and 20-beam radar correlations across bandwidths up to 150 MHz, but these systems can be scaled to process antenna arrays with thousands of beams across bandwidths up to 20 GHz. While these systems can process wide bandwidths for large antenna arrays, I also show an analysis that claims these systems can offer sensitivity levels comparable to other digital or analog beamformers.

  17. 1998 SPIE Smart Structures and Materials Conf. Paper #3329-19/3327-42 High bandwidth tunability in a smart vibration absorber

    E-print Network

    Flatau, Alison B.

    in a smart vibration absorber Alison B. Flatau, Marcelo J. Dapino and Frederick T. Calkinsà , Aerospace Engr, Phantom Works, Seattle WA 98124-2499 ABSTRACT The theory of an electrically tunable Terfenol-D vibration bandwidth tunability in the performance of a Terfenol-D vibration absorber. Keywords: vibration absorber

  18. Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers.

    PubMed

    Arenas, Celia; Leiva, Carlos; Vilches, Luis F; Cifuentes, Héctor

    2013-11-01

    The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk. PMID:23916843

  19. Characterization of the Mechanical Strength, Resorption Properties, and Histologic Characteristics of a Fully Absorbable Material (Poly-4-hydroxybutyrate—PHASIX Mesh) in a Porcine Model of Hernia Repair

    PubMed Central

    Deeken, Corey R.; Matthews, Brent D.

    2013-01-01

    Purpose. Poly-4-hydroxybutyrate (P4HB) is a naturally derived, absorbable polymer. P4HB has been manufactured into PHASIX Mesh and P4HB Plug designs for soft tissue repair. The objective of this study was to evaluate mechanical strength, resorption properties, and histologic characteristics in a porcine model. Methods. Bilateral defects were created in the abdominal wall of n = 20 Yucatan minipigs and repaired in a bridged fashion with PHASIX Mesh or P4HB Plug fixated with SorbaFix or permanent suture, respectively. Mechanical strength, resorption properties, and histologic characteristics were evaluated at 6, 12, 26, and 52 weeks (n = 5 each). Results. PHASIX Mesh and P4HB Plug repairs exhibited similar burst strength, stiffness, and molecular weight at all time points, with no significant differences detected between the two devices (P > 0.05). PHASIX Mesh and P4HB Plug repairs also demonstrated significantly greater burst strength and stiffness than native abdominal wall at all time points (P < 0.05), and material resorption increased significantly over time (P < 0.001). Inflammatory infiltrates were mononuclear, and both devices exhibited mild to moderate granulation tissue/vascularization. Conclusions. PHASIX Mesh and P4HB Plug demonstrated significant mechanical strength compared to native abdominal wall, despite significant material resorption over time. Histological assessment revealed a comparable mild inflammatory response and mild to moderate granulation tissue/vascularization. PMID:23781348

  20. Liquid metal reactor absorber technology

    SciTech Connect

    Pitner, A.L.

    1990-10-01

    The selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts. 3 refs., 3 figs.

  1. SHARAD Sounding Radar Observations of the Medusae Fossae Formation, Mars

    Microsoft Academic Search

    L. M. Carter; B. A. Campbell; T. R. Watters; R. Seu; R. J. Phillips; D. Biccari; J. W. Holt; C. Leuschen; J. J. Plaut; A. Safaeinili; R. Orosei; S. E. Smrekar; N. E. Putzig; A. F. Egan; F. Bernardini

    2008-01-01

    The SHARAD sounding radar on MRO sees through up to 560 m of the Medusae Fossae Formation material in two separate locations. The radar data can be used to measure the physical properties of this enigmatic deposit.

  2. Absorbent product to absorb fluids. [for collection of human wastes

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (inventors)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  3. Design and validation of optimal experiments for estimating thermal properties of composite materials

    Microsoft Academic Search

    Taktak

    1992-01-01

    Composite materials have gained an unprecedented interest in the last twenty years. Their superior strength-to-weight ratios have made them very popular with aerospace, automotive, boat, biomedical, and even the sporting goods industry. The radar-absorbing quality of composite materials, together with their strength-to-weight ratios, make these attractive for military applications. When used in air and space vehicles, composite materials are exposed

  4. RADAR PRINCIPLES I Introduction

    E-print Network

    Sato, Toru

    ) bands. Antenna size of weather radarsis a few to about ten metersin diameter, but an} atmospheric radar atmospheric radars have antennas witli dialneter of 10- 300 in. Weather radars cover a wide horizontal areaRADAR PRINCIPLES I Introduction Radar is a general technique, willcli has a wide range

  5. Limitations of Radar Coordinates

    E-print Network

    Donato Bini; Luca Lusanna; Bahram Mashhoon

    2004-12-17

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  6. Perfect Metamaterial Absorber

    Microsoft Academic Search

    N. I. Landy; S. Sajuyigbe; J. J. Mock; D. R. Smith; W. J. Padilla

    2008-01-01

    We present the design for an absorbing metamaterial (MM) with near unity absorbance A(omega). Our structure consists of two MM resonators that couple separately to electric and magnetic fields so as to absorb all incident radiation within a single unit cell layer. We fabricate, characterize, and analyze a MM absorber with a slightly lower predicted A(omega) of 96%. Unlike conventional

  7. Absorbent product and articles made therefrom

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (inventors)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  8. TRMM radar

    NASA Technical Reports Server (NTRS)

    Okamoto, Kenichi

    1993-01-01

    The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

  9. Radar observations in low earth orbit

    NASA Astrophysics Data System (ADS)

    Mehrholz, Dieter

    1997-05-01

    This paper presents an overview on radar techniques for the observation of space debris in low Earth orbits which were developed at FGAN in the frame of DARA and ESA/ESOC study contracts for the employment of the Tracking and Imaging Radar (TIRA) system in the past five years. For space debris observations TIRA is mainly operated in two different modes: In a tracking mode and in a beam-park mode of operation. Methods and algorithms were developed to analyse raw radar data, to compute radar images, and to estimate physical characteristics of space objects like size, shape, attitude, orbit, orbital lifetime, ballistic coefficient, mass, and material composition.

  10. Neutron absorbers and methods of forming at least a portion of a neutron absorber

    DOEpatents

    Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

    2014-12-02

    Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

  11. Radar: The Cassini Titan Radar Mapper

    Microsoft Academic Search

    C. Elachi; M. D. Allison; L. Borgarelli; P. Encrenaz; E. Im; M. A. Janssen; W. T. K. Johnson; R. L. Kirk; R. D. Lorenz; J. I. Lunine; D. O. Muhleman; S. J. Ostro; G. Picardi; F. Posa; C. G. Rapley; L. E. Roth; R. Seu; L. A. Soderblom; S. Vetrella; S. D. Wall; C. A. Wood; H. A. Zebker

    2004-01-01

    The Cassini RADAR instrument is a multimode 13.8 GHz multiple-beam sensor that can operate as a synthetic-aperture radar (SAR) imager, altimeter, scatterometer, and radiometer. The principal objective of the RADAR is to map the surface of Titan. This will be done in the imaging, scatterometer, and radiometer modes. The RADAR altimeter data will provide information on relative elevations in selected

  12. Future Trends in Automotive Radar \\/ Imaging Radar

    Microsoft Academic Search

    J. Wenger

    1998-01-01

    There is a growing interest of car manufacturers in sensors monitoring the car's surrounding area in order to improve safety systems from mere crash survival to crash prediction or prevention by early detection of hazardous situations. Therefore radar sensors have been intensively investigated for many years. A large variety of radar based vehicular sensors have been developed. Narrow-beam radars are

  13. Radar frequency radiation

    Microsoft Academic Search

    E. Malowicki

    1981-01-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar.

  14. GMTI MIMO radar

    Microsoft Academic Search

    D. W. Bliss; K. W. Forsythe; S. K. Davis; G. S. Fawcett; D. J. Rabideau; L. L. Horowitz; S. Kraut

    2009-01-01

    Multiple-input multiple-output (MIMO) extensions to radar systems enable a number of advantages compared to traditional approaches. These advantages include improved angle estimation and target detection. In this paper, MIMO ground moving target indication (GMTI) radar is addressed. The concept of coherent MIMO radar is introduced. Comparisons are presented comparing MIMO GMTI and traditional radar performance. Simulations and theoretical bounds for

  15. Spaceborne weather radar

    Microsoft Academic Search

    Robert Meneghini; Toshiaki Kozu

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of

  16. Wind shear radar simulation

    NASA Technical Reports Server (NTRS)

    Britt, Charles L.

    1988-01-01

    Viewgraphs used in a presentation on wind shear radar simulation are given. Information on a microburst model of radar reflectivity and wind velocity, radar pulse output, the calculation of radar return, microburst power spectrum, and simulation plans are given. A question and answer session is transcribed.

  17. Comet radar explorer

    NASA Astrophysics Data System (ADS)

    Farnham, Tony; Asphaug, Erik; Barucci, Antonella; Belton, Mike; Bockelee-Morvan, Dominique; Brownlee, Donald; Capria, Maria Teresa; Carter, Lynn; Chesley, Steve; Farnham, Tony; Gaskell, Robert; Gim, Young; Heggy, Essam; Herique, Alain; Klaasen, Ken; Kofman, Wlodek; Kreslavsky, Misha; Lisse, Casey; Orosei, Roberto; Plaut, Jeff; Scheeres, Dan

    The Comet Radar Explorer (CORE) is designed to perform a comprehensive and detailed exploration of the interior, surface, and inner coma structures of a scientifically impor-tant Jupiter family comet. These structures will be used to investigate the origins of cometary nuclei, their physical and geological evolution, and the mechanisms driving their spectacular activity. CORE is a high heritage spacecraft, injected by solar electric propulsion into orbit around a comet. It is capable of coherent deep radar imaging at decameter wavelengths, high resolution stereo color imaging, and near-IR imaging spectroscopy. Its primary objective is to obtain a high-resolution map of the interior structure of a comet nucleus at a resolution of ¿100 elements across the diameter. This structure shall be related to the surface geology and morphology, and to the structural details of the coma proximal to the nucleus. This is an ideal complement to the science from recent comet missions, providing insight into how comets work. Knowing the structure of the interior of a comet-what's inside-and how cometary activity works, is required before we can understand the requirements for a cryogenic sample return mission. But more than that, CORE is fundamental to understanding the origin of comets and their evolution in time. The mission is made feasible at low cost by the use of now-standard MARSIS-SHARAD reflec-tion radar imaging hardware and data processing, together with proven flight heritage of solar electric propulsion. Radar flight heritage has been demonstrated by the MARSIS radar on Mars Express (Picardi et al., Science 2005; Plaut et al., Science 2007), the SHARAD radar onboard the Mars Reconnaissance Orbiter (Seu et al., JGR 2007), and the LRS radar onboard Kaguya (Ono et al, EPS 2007). These instruments have discovered detailed subsurface structure to depths of several kilometers in a variety of terrains on Mars and the Moon. A reflection radar deployed in orbit about a comet will enjoy significant simplifying benefits compared to using the same instrument for Mars or lunar radar science: (1) The proximity of operations leads to a much higher signal to noise, as much as +30 dB. (2) The lack of an ionosphere simplifies data modeling and analysis. (3) The body is globally illuminated during every data acquisition, minimizing ambiguity or 'clutter' and allowing for tomographic reconstruction. What is novel is the data processing, where instead of a planar radargram approach we coherently process the data into an image of the deep interior. CORE thus uses a MARSIS-SHARAD heritage radar to make coherent reflection sounding measurements, a 'CAT SCAN' of a comet nucleus. What is unique about this mission compared to the Mars radars mentioned above, is that the target is a finite mass of dirty ice in free space, rather than a sheet of dirty ice draped on a planet surface. The depth of penetration (kilometers), attainable resolution (decameters), and the target materials, are more or less the same. This means that the science story is robust, and the radar implementation is robust. The target is comet 10P/Tempel 2, discovered by Wilhelm Tempel in 1873 and observed on most apparitions since. It has been extensively studied, in part because of interest as a CRAF target in the mid-1980s, and much is known about it. Tempel 2 is one of the largest known comet nuclei, 16×8×8 km (about the same size as Halley) [1] and has rotation period 8.9 hours [3,5,6,7,9]. The spin state is evolving with time, spinning up by ˜10 sec per perihelion pass [5,7]. The comet is active, but not exceedingly so, especially given its size. The water production is measured at ˜ 4 × 1028 mol/sec at its peak [2], a factor of 25 lower than comet Halley, and it is active over only ˜2% of its surface. The dust environment is well known, producing a factor of ˜100 less dust than Halley. Comet References: [1] A'Hearn et al., ApJ 347, 1155, 1989 [2] Feldman and Festou, ACM 1991, p. 171, 1992 [3] Jewitt and Luu, AJ 97, 1766, 1989 [4] Lamy et al., Comets II p 223. 2009 [5] Muel

  18. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P. (Idaho Falls, ID); Longhurst, Glen R. (Idaho Falls, ID); Porter, Douglas L. (Idaho Falls, ID); Parry, James R. (Idaho Falls, ID)

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  19. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J. (Latham, NY)

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  20. Modified Berenger PML absorbing boundary condition for FDTD meshes

    Microsoft Academic Search

    B. Chen; D. G. Fang; B. H. Zhou

    1995-01-01

    A new modified, perfectly matched layer absorbing boundary condition (MPML ABC) is presented. In the MPML, the introducing of extra degrees of freedom provides the possibility of adjusting the parameters of nonphysical material absorber (PML) for the purpose of enhancing the attenuation rate of the evanescent modes. Compared to Berenger PML, the MPML is more efficient in absorbing the evanescent

  1. Synthetic-aperture radar imaging through dispersive media

    E-print Network

    Cheney, Margaret

    ) the frequency bands of most radar systems are not wide enough for dispersive effects to be important. However homogeneous dispersive material, the scene to be imaged lies on a known surface, and the radar antenna flight vegetation. However, the method is also applicable to other dielectric materials where the dispersion

  2. Remorque RADAR Description technique

    E-print Network

    Heurteaux, Yanick

    ANNEXE: Remorque RADAR Description technique Le but de la remorque est de transporter un RADAR et pour héberger l'électronique radar et son opérateur. Caractéristiques générales de la remorque : · PTC'un côté, une baie de l'autre. Un hublot sur le toit et une baie donnant sur la partie RADAR. Un plafonnier

  3. UWB RADAR Receiver Architecture

    Microsoft Academic Search

    Nuno Paulino; Adolfo Steiger Garção; João Goes

    this chapter describes the operation of a radar system. The differences and advantages of using UWB signals in the radar system,\\u000a over traditional narrow band signals, are discussed. The radar equation, usually defined for narrow band signals, is redefined\\u000a for UWB signals. This new radar equation is used to analyze the echo signals from targets with basic shapes, resulting in

  4. Active Absorbers M. Rousseaua

    E-print Network

    Paris-Sud XI, Université de

    the theory for a point active absorber immersed in the anechoic field from a point source. This will apply with a plane wave. An extra oscillatory interference term occurs which should largely cancel in rooms due to the varying distances between all the source images and the absorber. Responses were measured in several rooms

  5. Cassini Titan Radar Mapper

    Microsoft Academic Search

    CHARLES ELACHI; E. Im; L. E. Roth; C. L. Werner

    1991-01-01

    The Cassini Titan Radar Mapper is a multimode radar instrument designed to probe the optically inaccessible surface of Titan, Saturn's largest moon. The instrument is to be included in the payload of the Cassini Saturn Mission, scheduled for launch in 1995. The individual modes of Cassini Radar Mapper will allow topographic mapping and surface imaging at few hundred meters resolution.

  6. Multispectral metamaterial absorber.

    PubMed

    Grant, J; McCrindle, I J H; Li, C; Cumming, D R S

    2014-03-01

    We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 ?m. This resonance is in addition to the THz metamaterial absorption resonance at 109 ?m (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging. PMID:24690713

  7. Selection of neutron-absorbing materials to improve the low-energy response of a Zr-based extended neutron monitor using Monte Carlo simulations.

    PubMed

    Biju, K; Sunil, C; Tripathy, S P; Joshi, D S; Bandyopadhyay, T; Sarkar, P K

    2015-02-01

    Monte Carlo simulations have been carried out using the FLUKA code to improve the neutron ambient dose equivalent [H*(10)] response of the ZReC (zirconium-lined portable neutron counter responding satisfactorily to neutrons up to 1 GeV) by introducing various neutron absorbers in the system such as cadmium, gadolinium, natural boron, enriched (10)B and borated polythene. It was found that ZReC can be effectively used as a portable neutron monitor by introducing any one of the following perforated layers: 5 mm thick natural boron, 0.5 mm thick enriched (10)B or 1 cm high-density polythene mixed with 50 % boron by weight. The integral response of the instrument was also calculated for some typical reference neutron fields. The relative ambient dose equivalent response of the said system is also found comparable with that of the existing LINUS neutron monitor. PMID:24891404

  8. Precision setup for certification of the modulus of reflection coefficients of radiation absorbing materials in the 1–3 GHz frequency range

    Microsoft Academic Search

    G. A. Vedyushkin; A. I. Svarovskaya; P. P. Tal'ko-Grintsevich; M. G. Chernyshev

    1985-01-01

    089.14:621.37\\/.39 Extensive use of radiolocationsystems, improved sensitivity of radio reception systems, and new developments in the field of special low-reflection materials and coatings have stimulated considerable interest in the measurement of reflection of magnetic waves from materials and natural media in the microwave range. Measurements of high reflection coefficients (RC) of materials are carried out by traditional methods based on

  9. Radar Meteorology Tutorial

    NSDL National Science Digital Library

    McNoldy, Brian

    Brian McNoldy at Multi-community Environmental Storm Observatory (MESO) educates the public about the use of radar in meteorology in this pdf document. After reading about the history of radar, visitors can find out how radar can detect storms by transmitting a high-power beam of radiation. Students can learn how scatter, absorption, frequencies, scan angles, and moments impact the radar display. With the help of many example images, the author also discusses how to interpret the images collected. At the end of the online document, visitors can learn about the characteristics and capabilities of NEXRAD WSR-88D, the radar used throughout the United States.

  10. Porous absorber for solar air heaters

    SciTech Connect

    Finch, J.A.

    1980-09-10

    A general discussion of the factors affecting solar collector performance is presented. Bench scale tests done to try to determine the heat transfer characteristics of various screen materials are explained. The design, performance, and evaluation of a crude collector with a simple screen stack absorber is treated. The more sophisticated absorber concept, and its first experimental approximation is examined. A short summary of future plans for the collector concept is included. (MHR)

  11. Multidimensional radar picture

    NASA Astrophysics Data System (ADS)

    Waz, Mariusz

    2010-05-01

    In marine navigation systems, the three-dimensional (3D) visualization is often and often used. Echosonders and sonars working in hydroacustic systems can present pictures in three dimensions. Currently, vector maps also offer 3D presentation. This presentation is used in aviation and underwater navigation. In the nearest future three-dimensional presentation may be obligatory presentation in displays of navigation systems. A part of these systems work with radar and communicates with it transmitting data in a digital form. 3D presentation of radar picture require a new technology to develop. In the first step it is necessary to compile digital form of radar signal. The modern navigation radar do not present data in three-dimensional form. Progress in technology of digital signal processing make it possible to create multidimensional radar pictures. For instance, the RSC (Radar Scan Converter) - digital radar picture recording and transforming tool can be used to create new picture online. Using RSC and techniques of modern computer graphics multidimensional radar pictures can be generated. The radar pictures mentioned should be readable for ECDIS. The paper presents a method for generating multidimensional radar picture from original signal coming from radar receiver.

  12. TECHNICAL NOTE: Design and development of electromagnetic absorbers with carbon fiber composites and matching dielectric layers

    NASA Astrophysics Data System (ADS)

    Neo, C. P.; Varadan, V. K.

    2001-10-01

    Radar absorbing materials are designed and developed with carbon fibers and suitable matching layers. Complex permittivities of carbon fiber composite are predicted on the basis that the modulus of permittivity obeys a logarithmic law of mixtures and the dielectric loss tangents are related through a linear law of mixtures. Linear regression analysis performed on the data points provides the constants which are used to predict the effective permittivities of carbon fiber composite at different frequencies. Using the free space measurement system, complex permittivities of the lossy dielectric at different frequencies are obtained. These complex permittivities are used to predict the reflectivity of a thin lossy dielectric layer on carbon fiber composite substrate. The predicted results agree quite well with the measured data. It is interesting to note that the thin lossy dielectric layer, about 0.03 mm thick, has helped to reduce the reflectivity of the 5.2 mm thick carbon fiber composite considerably.

  13. Multistatic radar systems signal processing

    Microsoft Academic Search

    I. Bradaric; G. T. Capraro; D. D. Weiner; M. C. Wicks

    2006-01-01

    In this paper, a multistatic radar system with multiple receivers and one transmitter is analyzed. We address the rules for selecting the weights for fusing multiple receivers in order to meet pre-specified performance goals. A multistatic radar ambiguity function is used to relate different radar performance measures to system parameters such as radar geometry and radar waveforms. Simulations are used

  14. Flexible metamaterial absorbers for stealth applications at terahertz frequencies.

    PubMed

    Iwaszczuk, Krzysztof; Strikwerda, Andrew C; Fan, Kebin; Zhang, Xin; Averitt, Richard D; Jepsen, Peter Uhd

    2012-01-01

    We have wrapped metallic cylinders with strongly absorbing metamaterials. These resonant structures, which are patterned on flexible substrates, smoothly coat the cylinder and give it an electromagnetic response designed to minimize its radar cross section. We compare the normal-incidence, small-beam reflection coefficient with the measurement of the far-field bistatic radar cross section of the sample, using a quasi-planar THz wave with a beam diameter significantly larger than the sample dimensions. In this geometry we demonstrate a near-400-fold reduction of the radar cross section at the design frequency of 0.87 THz. In addition we discuss the effect of finite sample dimensions and the spatial dependence of the reflection spectrum of the metamaterial. PMID:22274387

  15. Apollo experience report: Lunar module landing radar and rendezvous radar

    NASA Technical Reports Server (NTRS)

    Rozas, P.; Cunningham, A. R.

    1972-01-01

    A developmental history of the Apollo lunar module landing and rendezvous radar subsystems is presented. The Apollo radar subsystems are discussed from initial concept planning to flight configuration testing. The major radar subsystem accomplishments and problems are discussed.

  16. MIMO radar, SIMO radar, and IFIR radar: a P. P. Vaidyanathan and Piya Pal

    E-print Network

    Vaidyanathan, P. P.

    MIMO radar, SIMO radar, and IFIR radar: a comparison P. P. Vaidyanathan and Piya Pal Dept and SIMO radar systems for the case where the transmitter and receiver are collocated. The simplicity of the application allows one to see clearly where the advantages of MIMO radar come from, and what the tradeoffs are

  17. Radar in transition

    NASA Astrophysics Data System (ADS)

    Barton, D. K.

    1984-12-01

    It is pointed out that radar engineers, at the end of 1984, find their field in transition between the conventional designs of the post War II era and the digitally controlled, solid-state systems which will be in place for the year 2000. The U.S. Navy has two major phased array radar systems in operation, including the rotating three-dimensional (3D) AN/SPS-48, and the phased-scanned AN/SPY-1 (Aegis) radars. The Aegis represents a major step beyond the conventional 3D and mechanical fire-control radars. However, it requires a special ship, dedicated to its use. Attention is given to questions regarding an extension of the application of Aegis technology to other U.S. Navy applications and to other navies, an ambitious solid-state radar program in the UK, and Army radars.

  18. Radar performance improvement

    Microsoft Academic Search

    G. R. Little

    1976-01-01

    The AN\\/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made

  19. Caribbean Radar Cases

    NSDL National Science Digital Library

    2014-09-14

    This module presents radar case studies taken from events in the Caribbean that highlight radar signatures of severe weather. These cases include examples of deep convection, squall lines, bow echoes, tornadoes, and heavy rain resulting in flooding. Each case study includes a discussion of the conceptual models of each type of event as a review before showing the radar signatures and allowing the learner to analyze each one.

  20. OSCEE fan exhaust bulk absorber treatment evaluation

    NASA Technical Reports Server (NTRS)

    Bloomer, H. E.; Samanich, N. E.

    1980-01-01

    The acoustic suppression capability of bulk absorber material designed for use in the fan exhaust duct walls of the quiet clean short haul experiment engine (OCSEE UTW) was evaluated. The acoustic suppression to the original design for the engine fan duct which consisted of phased single degree-of-freedom wall treatment was tested with a splitter and also with the splitter removed. Peak suppression was about as predicted with the bulk absorber configuration, however, the broadband characteristics were not attained. Post test inspection revealed surface oil contamination on the bulk material which could have caused the loss in bandwidth suppression.

  1. Equatorial radar system

    NASA Technical Reports Server (NTRS)

    Rukao, S.; Tsuda, T.; Sato, T.; Kato, S.

    1989-01-01

    A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan Island, Indonesia (0.03 N, 109.3 E). The system is a 47 MHz monostatic Doppler radar with an active phased array configuration similar to that of the MU radar in Japan, which has been in successful operation since 1983. It will have a PA product of more than 5 x 10(9) sq. Wm (P = average transmitter power, A = effective antenna aperture) with sensitivity more than 10 times that of the MU radar. This system configuration enables pulse-to-pulse beam steering within 25 deg from the zenith. As is the case of the MU radar, a variety of sophisticated operations will be made feasible under the supervision of the radar controller. A brief description of the system configuration is presented.

  2. The Invisible Radar Triangle

    NSDL National Science Digital Library

    2014-09-18

    Students learn about radar imaging and its various military and civilian applications that include recognition and detection of human-made targets, and the monitoring of space, deforestation and oil spills. They learn how the concepts of similarity and scaling are used in radar imaging to create three-dimensional models of various targets. Students apply the critical attributes of similar figures to create scale models of a radar imaging scenario using infrared range sensors (to emulate radar functions) and toy airplanes (to emulate targets). They use technology tools to measure angles and distances, and relate the concept of similar figures to real-world applications.

  3. Generalized radar/radiometry imaging problems

    E-print Network

    Genève, Université de

    Paper Generalized radar/radiometry imaging problems Ivan Prudyus, Sviatoslav Voloshynovskiy, Andriy- ing simulation based on radar, synthetic aperture radar (SAR) and radiometry systems are presented systems, synthetic aperture radar, spatio-temporal imaging. 1. Introduction Resolution of radar

  4. Shock absorber servicing tool

    NASA Technical Reports Server (NTRS)

    Koepler, Jack L. (Inventor); Hill, Robert L. (Inventor)

    1981-01-01

    A tool to assist in the servicing of a shock absorber wherein the shock absorber is constructed of a pair of aligned gas and liquid filled chambers. Each of the chambers is separated by a movable separator member. Maximum efficiency of the shock absorber is achieved in the locating of a precise volume of gas within the gas chamber and a precise volume of liquid within the liquid chamber. The servicing tool of this invention employs a rod which is to connect with the separator and by observation of the position of the rod with respect to the gauge body, the location of the separator is ascertained even though it is not directly observable.

  5. Mechanical energy absorber

    NASA Astrophysics Data System (ADS)

    Wesselski, Clarence J.

    1995-06-01

    An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

  6. Mechanical energy absorber

    NASA Astrophysics Data System (ADS)

    Wesselski, Clarence J.

    1993-07-01

    An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

  7. A hybrid mesoporous material functionalized by 1,8-naphthalimide-base receptor and the application as chemosensor and absorbent for Hg2+ in water.

    PubMed

    Meng, Qingtao; Zhang, Xiaolin; He, Cheng; Zhou, Peng; Su, Weiping; Duan, Chunying

    2011-03-15

    A novel hybrid material (SBA-P1) is prepared through the functionalization of mesoporous silica (SBA-15) with a 1,8-naphthalimide-based dye by sol-gel reaction. The characterization results of elemental analysis (EA), X-ray powder diffractometer (XRD) and spectroscopic methods demonstrate the fluorescence dye P1 is successfully grafted onto the inner surface of SBA-15 and the organized structure is preserved. SBA-P1 can detect Hg(2+) with high selectivity to Cu(2+), Zn(2+), Cd(2+), Pb(2+), Mn(2+), Ni(2+), Co(2+), Ag(+), Cr(3+), and Mg(2+), Ca(2+), Li(+), Na(+), K(+) in water and sensitivity to environmentally relevant mercury in complex natural samples. The quenching fluorescence detection is also reversible by treating with EDTA/base. Furthermore, its fluorescence intensity keeps stable in the physiologically relevant pH range. The extraction ability of SBA-P1 is also estimated by inductively coupled plasma source mass spectrometer (ICP), showing that approximately 90% of the Hg(2+) ion is extracted. These results imply that the hybrid material has potential application for sensing and removing of Hg(2+) ions in waste water and working as toxicide for acute mercury poisoning. PMID:21315897

  8. Shock Absorbing Helmets

    NASA Technical Reports Server (NTRS)

    1978-01-01

    This paper presents a description of helmets used by football players that offer three times the shock-absorbing capacity of earlier types. An interior padding for the helmets, composed of Temper Foam, first used by NASA's Ames Research Center in the design of aircraft seats is described.

  9. Internal absorber solar collector

    Microsoft Academic Search

    S. B. Herskovitz; F. S. Holt; C. J. Sletten; E. J. Sletten

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60° in

  10. Internal absorber solar collector

    Microsoft Academic Search

    Carlyle J. Sletten; Sheldon B. Herskovitz; F. S. Holt; E. J. Sletten

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in

  11. Java Radar Analysis Tool

    NASA Technical Reports Server (NTRS)

    Zaczek, Mariusz P.

    2005-01-01

    Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

  12. Noncooperative rendezvous radar system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

  13. Decoders for MST radars

    NASA Technical Reports Server (NTRS)

    Woodman, R. F.

    1983-01-01

    Decoding techniques and equipment used by MST radars are described and some recommendations for new systems are presented. Decoding can be done either by software in special-purpose (array processors, etc.) or general-purpose computers or in specially designed digital decoders. Both software and hardware decoders are discussed and the special case of decoding for bistatic radars is examined.

  14. Phased-array radars

    Microsoft Academic Search

    Eli Brookner

    1985-01-01

    The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US

  15. Determination of radar MTF

    SciTech Connect

    Chambers, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  16. Active radar stealth device

    Microsoft Academic Search

    R. N. Cain; Albert J. Corda

    1991-01-01

    This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector\\/emitter pairs contained within the coating detect and actively cancel, respectively,

  17. Perfect terahertz absorber using fishnet based metafilm

    SciTech Connect

    Azad, Abul Kalam [Los Alamos National Laboratory; Shchegolkov, Dmitry Yu [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; Smirnova, E I [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  18. Looking at Radar Images

    NSDL National Science Digital Library

    These activities pertain to the value of the different types of images, including a false color mosaic, a Compressed Stokes image, a vegetation map and key, and various ground photographs. Students are given specific directions on how to decide what features of a radar image indicate such structures as upland forest, clear-cut areas, and roads. In a second activity, students look at the radar images to see if they can produce a vegetation map similar to the one they have been given. The third activity introduces 15 Decade Volcanoes that pose a particular threat to humans. Using the Decade Volcanoes as examples, students view radar images of volcanoes that occur around the world. The final exercise is aimed at helping students distinguish the differences between radar image data and visible photographs. Students will look at radar data and photographs of three sites taken by the astronauts.

  19. Spaceborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

  20. Browse > Conferences> Radar Conference, 2008. RADAR ... INDEX TERMS

    E-print Network

    Préaux, Jean-Philippe

    Browse > Conferences> Radar Conference, 2008. RADAR ... INDEX TERMS REFERENCES CITING DOCUMENTS Force, MorphoAnalysis in Signal Process. Lab., Salon-de-Provence This paper appears in: Radar Conference, 2008. RADAR '08. IEEE Issue Date: 26-30 May 2008 On page(s): 1 - 5 Location: Rome ISSN: 1097-5659 Print

  1. Shock absorbing mount for electrical components

    NASA Technical Reports Server (NTRS)

    Dillon, R. F., Jr.; Mayne, R. C. (inventors)

    1975-01-01

    A shock mount for installing electrical components on circuit boards is described. The shock absorber is made of viscoelastic material which interconnects the electrical components. With this system, shocks imposed on one component of the circuit are not transmitted to other components. A diagram of a typical circuit is provided.

  2. Optimization and engineering of microwave absorbers

    Microsoft Academic Search

    Kuo-Liang Chen

    1998-01-01

    In this thesis, a concerted effort has been made to study and evaluate the individual electromagnetic properties of the absorbing components including carbon black, conducting fibers, metal flakes, magnetic materials such as carbonyl iron, ferrite and the chiral type of micro- carbon coil. The study of the electromagnetic properties covers functions such as dielectric dissipation, random scattering effect at low

  3. Use and Interpretation of Radar

    NSDL National Science Digital Library

    John Nielsen-Gammon

    1996-01-01

    This undergraduate meteorology tutorial from Texas A&M University discusses the basic principles of operation of weather radars, describes how to interpret radar mosaics, and discusses the use of radar in weather forecasting. Students learn the relationship between range and elevation and how to use radar images and mosaics in short-range forecasting.

  4. Ground-penetrating radar methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground-penetrating radar geophysical methods are finding greater and greater use in agriculture. With the ground-penetrating radar (GPR) method, an electromagnetic radio energy (radar) pulse is directed into the subsurface, followed by measurement of the elapsed time taken by the radar signal as it ...

  5. Radar remote sensing in biology

    USGS Publications Warehouse

    Moore, Richard K.; Simonett, David S.

    1967-01-01

    The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

  6. FREQUENCY DEPENDENT ATTENUATION ANALYSIS OF GROUND-PENETRATING RADAR DATA

    E-print Network

    Barrash, Warren

    FREQUENCY DEPENDENT ATTENUATION ANALYSIS OF GROUND- PENETRATING RADAR DATA John H. Bradford, CGISS, Boise State University, Boise, ID Abstract I investigate the frequency dependence of attenuation materials attenuation is approximately linear with frequency over the bandwidth of the GPR signal

  7. An overview of impulse radar phenomenon

    Microsoft Academic Search

    David L. Black; ASDIENA CR; Wright-Patterson AFB

    1992-01-01

    An overview is presented of some of the interesting issues concerning impulse waveforms on materials. An attempt is made to analyze such phenomena as molecular relaxation, signal precursor effects, self-induced transparency, and the natural resonance theory. Proposed applications for impulse radar are discussed

  8. Radar detection of wetland ecosystems: a review

    Microsoft Academic Search

    Floyd M. Henderson; Anthony J. Lewis

    2008-01-01

    Periodically, reviews of our knowledge of radar–wetland relationships and detection parameters have been provided by various authors. Since the publication of these works, additional research has been completed. Five major remote sensing journals spanning the years 1965–2007 formed the basis of this review. The vast majority of significant material found its way into these mainstream journals in one aspect or

  9. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  10. Radar frequency radiation

    NASA Astrophysics Data System (ADS)

    Malowicki, E.

    1981-11-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar. The method is based on the following main assumptions that: (a) the total field can be computed as the vector summation of the individual fields due to each antenna element; (b) the individual field can be calculated using distances for which the field point is in the far field of the antenna element. An RFR computer program was coded for the RADC HE 6180 digital computer and exercised to calculate the radiation levels in the air and ground space for the present baseline and the possible Six DB and 10 DB growth systems of the PAVE PAWS radar system at OTIS AFB MA. The average radiation levels due to the surveillance fence were computed for three regions: in the air space in front of the radar, at the radar hazard fence at OTIS AFB MA and at representative ground points in the OTIS AFB vicinity. It was concluded that the radar frequency radiation of PAVE PAWS does not present a hazard to personnel provided there is no entry to the air hazard zone or to the area within the hazard fence. The method developed offers a cost effective way to determine radiation levels from a phased array radar especially in the near field and transition regions.

  11. SELECTIVE ABSORBER COATED FOILS FOR SOLAR COLLECTORS

    SciTech Connect

    Lampert, Carl M.

    1980-04-01

    Solar absorber metal foils are discussed in terms of materials and basic processing science. Also included is the use of finished heavy sheet stock for direct fabrication of solar collector panels. Both the adhesives and bonding methods for foils and sheet are surveyed. Developmental and representative commercial foils are used as illustrative examples. As a result it was found that foils can compete economically with batch plating but are limited by adhesive temperature stability. Also absorber foils are very versatile and direct collector fabrication from heavy foils appears very promising.

  12. Spaceborne laser radar.

    PubMed

    Flom, T

    1972-02-01

    Laser radar systems are being developed to acquire and track targets in applications such as the rendezvous and docking of two spacecraft. To search effectively for and locate a target using a narrow laser beam, a scanning system is needed. This paper describes a scan technique whereby a narrow laser beam is synchronously scanned with an equally narrow receiver field-of-view without the aid of mechanical gimbals. Equations are developed in order to examine the maximum acquisition and tracking rates, and the maximum target range for a scanning laser radar system. A recently built prototype of a small, lightweight, low-power-consuming scanning laser radar is described. PMID:20111497

  13. Radar transmitter procedures

    NASA Astrophysics Data System (ADS)

    1993-03-01

    This ITOP outlines the test methods used in evaluating the performance and characteristics of general types of radar transmitters to include single or variable frequency transmitters. The test methods serve as a guide in determining the overall efficiency of such equipment as a function of their design and their recorded performance. This ITOP is limited to methods for measuring the performance of the radar transmitter under test as a major component. Some performance aspects of the transmitter can be tested only when configured as part of a total radar system.

  14. Infrared Imaging Video Bolometer with a Double Layer Absorbing Foil

    Microsoft Academic Search

    Igor V. MIROSHNIKOV; Artem Y. KOSTRYUKOV; Byron J. PETERSON

    2007-01-01

    The object of the present paper is an infrared video bolometer with a bolometer foil consisting of two layers: the first layer is constructed of radia tion absorbing blocks and the second layer is a thermal isolating base. The absorbing blocks made of a material with a high photon attenuation coefficient (gold) were spatially separated from each other while the

  15. Infrared Imaging Video Bolometer with a Double Layer Absorbing Foil

    Microsoft Academic Search

    Igor V. Miroshnikov; Artem Y. Kostryukov; Byron J. Peterson

    2008-01-01

    The object of the present paper is an infrared video bolometer with a bolometer foil consisting of two layers: the first layer is constructed of radiation absorbing blocks and the second layer is a thermal isolating base. The absorbing blocks made of a material with a high photon attenuation coefficient (gold) were spatially separated from each other while the base

  16. Absorption properties of carbon black\\/silicon carbide microwave absorbers

    Microsoft Academic Search

    Xiangxuan Liu; Zeyang Zhang; Youpeng Wu

    2011-01-01

    An absorbing medium is prepared using nanosize carbon black (CB) blended with nanosize silicon carbide (SiC). The medium improves the wave absorption properties and the wave band of the single CB absorbent. The microstructure, conductivity, dielectric property, and microwave absorption of the material are studied by means of field emission scanning electron microscopy, trielectrode method, and vector network analyzer respectively.

  17. Passive-adaptive vibration absorbers using shape memory alloys

    Microsoft Academic Search

    Keith A. Williams; George T. Chiu; Robert Bernhard

    1999-01-01

    The passive-adaptive approach to vibration control shows promise in its ability to combine the robust stability and low-complexity of passive tuned absorbers with the adaptability of active control schemes. Previous tunable vibration absorbers have been complex and bulky. Shape memory alloys (SMA) with their variable material properties, offer an alternative adaptive mechanism. Heating an SMA causes a change in the

  18. A new type of EM wave absorbing coating

    NASA Astrophysics Data System (ADS)

    Gauss, A., Jr.

    1982-06-01

    Research on radar anti-reflection coatings has been actively pursued both theoretically and experimentally since World War II. Interference, (1,2) dielectric (3), and magnetic-dielectric (4,5) absorptive coatings have been tried. Recently a new type of radar absorbing chaff (RAC) has been suggested (6). Calculations done at BRL indicate that by compacting the RAC filaments a new type of radar absorbing coating (called RACO) may be possible. The filaments would be fixed in a solid binder having near unity dielectric constant. The primary mechanism for attenuation of the incident radiation by a RAC cloud or RACO layer is by resistive dissipation in the relatively long, thin chaff filaments. The tiny RAC-RACO filaments have length to diameter ratios on the order of one thousand with diameters of about 500A. Filament separations in a RACO are about one-half to one-third of a filament length thus requiring the inclusion of dipole and perhaps higher order interactions. Each filament can be modeled simply as a series resistive-capacitive circuit, single filament theory will be discussed in Section 2.

  19. The Comet Radar Explorer Mission

    NASA Astrophysics Data System (ADS)

    Asphaug, Erik; Belton, Mike; Bockelee-Morvan, Dominique; Chesley, Steve; Delbo, Marco; Farnham, Tony; Gim, Yonggyu; Grimm, Robert; Herique, Alain; Kofman, Wlodek; Oberst, Juergen; Orosei, Roberto; Piqueux, Sylvain; Plaut, Jeff; Robinson, Mark; Sava, Paul; Heggy, Essam; Kurth, William; Scheeres, Dan; Denevi, Brett; Turtle, Elizabeth; Weissman, Paul

    2014-11-01

    Missions to cometary nuclei have revealed major geological surprises: (1) Global scale layers - do these persist through to the interior? Are they a record of primary accretion? (2) Smooth regions - are they landslides originating on the surface? Are they cryovolcanic? (3) Pits - are they impact craters or sublimation pits, or rooted in the interior? Unambiguous answers to these and other questions can be obtained by high definition 3D radar reflection imaging (RRI) of internal structure. RRI can answer many of the great unknowns in planetary science: How do primitive bodies accrete? Are cometary nuclei mostly ice? What drives their spectacular activity and evolution? The Comet Radar Explorer (CORE) mission will image the detailed internal structure of the nucleus of 10P/Tempel 2. This ~16 x 8 x 7 km Jupiter Family Comet (JFC), or its parent body, originated in the outer planets region possibly millions of years before planet formation. CORE arrives post-perihelion and observes the comet’s waning activity from safe distance. Once the nucleus is largely dormant, the spacecraft enters a ~20-km dedicated Radar Mapping Orbit (RMO). The exacting design of the RRI experiment and the precise navigation of RMO will achieve a highly focused 3D radar reflection image of internal structure, to tens of meters resolution, and tomographic images of velocity and attenuation to hundreds of meters resolution, tied to the gravity model and shape. Visible imagers will produce maps of the surface morphology, albedo, color, texture, and photometric response, and images for navigation and shape determination. The cameras will also monitor the structure and dynamics of the coma, and its dusty jets, allowing their correlation in 3D with deep interior structures and surface features. Repeated global high-resolution thermal images will probe the near-surface layers heated by the Sun. Derived maps of thermal inertia will be correlated with the radar boundary response, and photometry and texture, probing surface materials attainable by future robotic excavation missions. Thermal images will reveal areas of sublimation cooling around vents and pits, and the secular response of the outer meters as the nucleus moves farther from the Sun.

  20. Radar - The Future

    NASA Astrophysics Data System (ADS)

    Warwick, G.

    1985-02-01

    Progress in civil and military radar units since the invention of radar in 1935 is summarized, noting the trend to multipurpose units. The earliest systems functioned at 10 cm, then 3 cm after development of a cavity magnetron to provide power for shorter wavelengths. Military needs are driving improvements in three-dimensional scanning capabilities, Primarily to locate aircraft in the presence of ground clutter and sea surface scattering. Autonomous, separate transmitter and receiver units are being tested. Lengthening ground-based radar wavelengths to tens of meters will permit over-the-horizon sensing with backscattering, ionospheric bounce, or induction of a potential in the sea surface as the possible techniques. Mode S monopulse radars will permit transponder queries between small and large aircraft. Finally, pulse Doppler SAR systems may afford terrain recognition with no corroborating data except an expert systems data base.

  1. Caribbean Radar Products

    NSDL National Science Digital Library

    2014-09-14

    This module provides examples of radar imagery from various locations in the Caribbean to demonstrate the different types of images available. Also, examples of different meteorological and non meteorological features are presented to show features seen in island locations.

  2. Millimeter Waves Ballistic Radar

    Microsoft Academic Search

    A. N. Zubkov; V. S. Gavrilov; Ya. M. Kempa; Z. V. Dufanets; N. A. Naumets

    2006-01-01

    Solid-state Doppler millimeter waves ballistic radar designed for measuring of exterior and interior ballistic parameters of highly dynamical faint objects is developed. The coherence characteristics of transmit-receive module are supported by the floating heterodyne oscillation behavior

  3. Active radar stealth device

    NASA Astrophysics Data System (ADS)

    Cain, R. N.; Corda, Albert J.

    1991-07-01

    This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector/emitter pairs contained within the coating detect and actively cancel, respectively, the microwave field at each respective detector/emitter pair.

  4. Cassini Radar hardware technologies

    SciTech Connect

    Wheeler, K.; Renick, P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

    1996-03-01

    The hardware development portion of the Cassini Radar task is complete. The flight model Digital Assembly and Energy Storage Assembly have been integrated and tested, as has the engineering/qualification model Radio Frequency Electronics Assembly. Integration of the flight model Radio Frequency Electronics Assembly is ready to begin. The intent of this paper is to describe some of the more interesting technologies implemented in the electronics to achieve the requirements of the Cassini Radar experiment. {copyright} {ital 1996 American Institute of Physics.}

  5. Phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, E.

    1985-02-01

    The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.

  6. Multiresolution GMTI radar

    Microsoft Academic Search

    J. R. Guerci; A. O. Steinhardt

    2003-01-01

    The detection and tracking of ground moving vehicles from airborne radar can be challenging at slow target velocities due to the close space-time (angle-Doppler) proximity of strong competing mainbeam clutter. Moreover, in complex non-stationary clutter environments, conventional space-time adaptive processing (STAP) cannot be relied upon to provide precision ing. In this paper, we re-examine GMTI radar from a multiresolution perspective

  7. Weather Radar Network Design

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2008-01-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively amounting to a greater ability to measure

  8. Terminal Doppler weather radar

    Microsoft Academic Search

    M. Michelson; W. W. Shrader; J. G. Wieler

    1990-01-01

    The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver\\/exciter, the digital signal processor, and the radar product generator\\/remote monitoring subsystem. Attention is also given to the processes of the

  9. Doppler Radar Technology

    NSDL National Science Digital Library

    This resource provides an introduction to the function and uses of the The National Weather Service's (NWS) Weather Surveillance Doppler Radar (WSR-88D). Topics include the components of the system, an overview of the products and overlays the system creates, and some example images with captions explaining what is being shown. There are also links to radar meteorology tutorials and to information on training to use the system and interpret its imagery.

  10. Radar network characterization

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2007-01-01

    The use of dense networks of small radars for weather sensing is being investigated by the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere, with a first test-bed of this new paradigm well underway. The potential benefits of closely-deployed, overlapping, short-range weather radars are easy to see intuitively, and can be summarized as a greater ability to mitigate

  11. Electrochemical Corrosion Testing of Neutron Absorber Materials

    SciTech Connect

    Tedd Lister; Ron Mizia; Arnold Erickson; Tammy Trowbridge

    2007-05-01

    This report summarizes the results of crevice-corrosion tests for six alloys in solutions representative of ionic compositions inside the Yucca Mountain waste package should a breech occur. The alloys in these tests are Neutronit A978a (ingot metallurgy, hot rolled), Neutrosorb Plus 304B4 Grade Ab (powder metallurgy, hot rolled), Neutrosorb Plus 304B5 Grade Ab (powder metallurgy, hot rolled), Neutrosorb Plus 304B6 Grade Ab (powder metallurgy, hot rolled), Ni-Cr-Mo-Gd alloy2 (ingot metallurgy, hot rolled), and Alloy 22 (ingot metallurgy, hot rolled).

  12. Sensing with THz metamaterial absorbers

    E-print Network

    Cong, Longqing

    2014-01-01

    Metamaterial perfect absorbers from microwaves to optical part of the electromagnetic spectrum has been intensely studied for its ability to absorb electromagnetic radiation. Perfect absorption of light by metamaterials have opened up new opportunities for application oriented functionalities such as efficient sensors and emitters. We present an absorber based sensing scheme at the terahertz frequencies and discuss optimized designs to achieve high frequency and amplitude sensitivities. The major advantage of a perfect metamaterial absorber as a sensor is the sensitive shift in the absorber resonance frequency along with the sharp change in the amplitude of the resonance due to strong interaction of the analyte with the electric and the magnetic fields at resonant perfect absorption frequency. We compare the sensing performance of the perfect metamaterial absorber with its complementary structural design and planar metasurface with identical structure. The best FoM values obtained for the absorber sensor here...

  13. Metamaterial saturable absorber mirror.

    PubMed

    Dayal, Govind; Ramakrishna, S Anantha

    2013-02-01

    We propose a metamaterial saturable absorber mirror at midinfrared wavelengths that can show a saturation of absorption with intensity of incident light and switch to a reflecting state. The design consists of an array of circular metallic disks separated by a thin film of vanadium dioxide (VO(2)) from a continuous metallic film. The heating due to the absorption in the absorptive state causes the VO(2) to transit to a metallic phase from the low temperature insulating phase. The metamaterial switches from an absorptive state (R?0.1%) to a reflective state (R>95%) for a specific threshold intensity of the incident radiation corresponding to the phase transition of VO(2), resulting in the saturation of absorption in the metamaterial. The computer simulations show over 99.9% peak absorbance, a resonant bandwidth of about 0.8 ?m at 10.22 ?m wavelengths, and saturation intensity of 140 mW cm(-2) for undoped VO(2) at room temperature. We also carried out numerical simulations to investigate the effects of localized heating and temperature distribution by solving the heat diffusion problem. PMID:23381408

  14. Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers (Ligda)

    E-print Network

    Rutledge, Steven

    Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers similar observations in the early 1940's (U.S. Air Corps meteorologists receiving "radar" training at MIT in 1943 First operational weather radar, Panama, 1943 Science of radar meteorology born from WWII research

  15. Coherent backscatter and the radar characteristics of outer planet satellites

    Microsoft Academic Search

    Bruce Hapke

    1990-01-01

    It is presently suggested that the diffuse component-dominated high radar reflectivities and large polarization of Europa, Ganymede, and Callisto could be due to the illumination by a collimated source of a weakly absorbing particulate medium in which wavelength-scaled scatterers are separated by distances somewhat larger than the wavelength. A plausible medium could be a regolith composed of voids and\\/or silicate

  16. Weather Radar and Instrumentation: Laboratory Modules

    NSDL National Science Digital Library

    These 16 radar education modules, developed for the Weather Radar and Instrumentation Curriculum at the University of Oklahoma, provide hands-on instruction for beginning, intermediate, or advanced students to learn about radar systems, especially weather radar. Topics include hardware, weather radar, adaptive systems, advanced hydrometeors, applications of weather radar, and atmospheric interpretations. The modules may be downloaded.

  17. Microphysical cross validation of spaceborne radar and ground polarimetric radar

    Microsoft Academic Search

    V. Chandrasekar; Steven M. Bolen; Eugenio Gorgucci

    2003-01-01

    Ground-based polarimetric radar observations along the beam path of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), matched in resolution volume and aligned to PR measurements, are used to estimate the parameters of a gamma raindrop size distribution (RSD) model along the radar beam in the presence of rain. The PR operates at 13.8 GHz, and its signal returns

  18. RADAR: THE CASSINI TITAN RADAR MAPPER C. ELACHI1,

    E-print Network

    RADAR: THE CASSINI TITAN RADAR MAPPER C. ELACHI1, , M. D. ALLISON2 , L. BORGARELLI3 , P. ENCRENAZ4; Accepted in final form 3 June 1999) Abstract. The Cassini RADAR instrument is a multimode 13.8 GHz multiple coefficient as low as -40 dB. 1. Introduction The Cassini spacecraft, launched on October 15, 1997, carries

  19. Minimum radar cross section bounds for passive radar responsive tags

    Microsoft Academic Search

    P. Bidigare; T. Stevens; B Correll; M. Beauvais

    2004-01-01

    A common problem in ground moving target indication (GMTI) radar is detecting a target with even a large radar cross section (RCS) when its line-of-sight velocity falls below the minimum detectable velocity (MDV) for that radar system. In a cooperative scenario, a target may employ a tagging device, which can shift or spread its Doppler signature to become more detectable.

  20. Microwave emissions from police radar 

    E-print Network

    Fink, John Michael

    1994-01-01

    The purpose of this study was to evaluate police officers exposures to microwaves emitted by traffic radar units at the ocular and testicular level. Additionally, comparisons were made of the radar manufacturers published maximum power density...

  1. Venus wind-altitude radar

    NASA Technical Reports Server (NTRS)

    Levanon, N.

    1974-01-01

    A design study on adding a radar altimeter to the Pioneer Venus small probe is review. Block and timing diagrams are provided. The inherent and interface ambiguities, resolution, and data handling logic for radar altimeters are described.

  2. Systems and Methods for Radar Data Communication

    NASA Technical Reports Server (NTRS)

    Bunch, Brian (Inventor); Szeto, Roland (Inventor); Miller, Brad (Inventor)

    2013-01-01

    A radar information processing system is operable to process high bandwidth radar information received from a radar system into low bandwidth radar information that may be communicated to a low bandwidth connection coupled to an electronic flight bag (EFB). An exemplary embodiment receives radar information from a radar system, the radar information communicated from the radar system at a first bandwidth; processes the received radar information into processed radar information, the processed radar information configured for communication over a connection operable at a second bandwidth, the second bandwidth lower than the first bandwidth; and communicates the radar information from a radar system, the radar information communicated from the radar system at a first bandwidth.

  3. A review of array radars

    Microsoft Academic Search

    E. Brookner

    1981-01-01

    Achievements in the area of array radars are illustrated by such activities as the operational deployment of the large high-power, high-range-resolution Cobra Dane; the operational deployment of two all-solid-state high-power, large UHF Pave Paws radars; and the development of the SAM multifunction Patriot radar. This paper reviews the following topics: array radars steered in azimuth and elevation by phase shifting

  4. Electrochemical cells having hydrogen gas absorbing agent

    Microsoft Academic Search

    F. E. Parsen; T. T. Yatabe

    1982-01-01

    An agent which absorbs hydrogen gas for electrochemical cells is made from an oxide of manganese and nickel, cobalt or iron. At temperatures above about 40°C., the oxide of manganese can be replaced by lead oxide. Hydrophobic binders can be added to the agent or the agent can be microencapsulated in water-impermeable but hydrogen-gas-permeable materials. The agent is preferably added

  5. Radar sector blanker

    NASA Astrophysics Data System (ADS)

    Hall, Roger B.

    1994-03-01

    A radar sector blanker comprises in analog-to-digital converter and a sector controller unit. The analog-to-digital converter receives the analog synchro voltages describing the positioning of a radar antenna and changes these voltages into binary-coded decimal (BCD) information. The sector controller unit comprises a portable housing, a controller system, and a power supply. The controller system includes an OFF comparator circuit, an ON comparator circuit, an S-R latch, and a solid-state switch. Each comparator circuit comprises three cascaded transistor-transistor logic (TTL) integrated chips. The power supply gives a direct-current voltage to the solid-state switch and the TTL chips. The sector blanker blocks transmission for a predetermined rotational region or sector of a radar system.

  6. The Clementine Bistatic Radar Experiment

    Microsoft Academic Search

    S. Nozette; C. L. Lichtenberg; P. Spudis; R. Bonner; W. Ort; E. Malaret; M. Robinson; E. M. Shoemaker

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar

  7. The Shuttle Radar Topography Mission

    Microsoft Academic Search

    Tom G. Farr; Paul A. Rosen; Edward Caro; Robert Crippen; Riley Duren; Scott Hensley; Michael Kobrick; Mimi Paller; Ernesto Rodriguez; Ladislav Roth; David Seal; Scott Shaffer; Joanne Shimada; Jeffrey Umland; Marian Werner; Michael Oskin; Douglas Burbank; Douglas Alsdorf

    2007-01-01

    The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution.

  8. Target identification from radar signatures

    Microsoft Academic Search

    R. Strattan

    1978-01-01

    Modern high resolution radar techniques and real time digital signal processing advances indicate the feasibility of extracting characteristic features of aircraft targets from their radar signatures. Two basic approaches have been suggested. The low frequency approach utilizes harmonically related radar frequencies with wavelengths comparable to the target dimensions. The microwave approach utilizes spread spectrum techniques to achieve high range resolution.

  9. SEASAT Synthetic Aperture Radar Data

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.

    1981-01-01

    The potential of radar imagery from space altitudes is discussed and the advantages of radar over passive sensor systems are outlined. Specific reference is made to the SEASAT synthetic aperture radar. Possible applications include oil spill monitoring, snow and ice reconnaissance, mineral exploration, and monitoring phenomena in the urban environment.

  10. Review of current radar interests

    Microsoft Academic Search

    M. I. Skolnik

    1974-01-01

    Current radar applications and problem areas are reviewed. Air traffic control, aircraft and ship navigation, remote sensing, and law enforcement are some of the applications mentioned. Both the Gemini and the Apollo space vehicles used radar for rendezvous and docking, and Apollo also utilized it for lunar landing. Equipment improvements suggested include better isolation in CW radar, efficient linear transmitters,

  11. A radar tour of Venus

    Microsoft Academic Search

    J. K. Beatty

    1985-01-01

    The surface of Venus is briefly characterized in a summary of results obtained by the Soviet Venera 15 and 16 8-cm synthetic-aperture radars, IR radiometers, and radar altimeters. A series of radar images, mainly from Kotelnikov et al. (1984), are presented and discussed, and the descent vehicles to be released by the two Vega spacecraft as they pass Venus in

  12. Analysis of Random Radar Networks

    E-print Network

    Adve, Raviraj

    a design tradeoff between spatial diversity and interference cancellation for multistatic radar networksAnalysis of Random Radar Networks Rani Daher, Raviraj Adve Department of Electrical and Computer.daher@utoronto.ca, rsadve@comm.utoronto.ca Abstract--We introduce the notion of random radar networks to analyze the effect

  13. Analysis of weather radar return

    Microsoft Academic Search

    D. Payne

    1977-01-01

    A mathematical model of detected clutter from an airborne weather radar of conventional design is developed. The model is the joint probability density of samples of radar return from hydrometeors at the same nominal range and scan angle. It is developed from analysis of the effect on the received signal of the following parameters: inhomogeneous hydrometeor motion, radar frequency stability,

  14. Spaceborne Imaging Radar Symposium

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1983-01-01

    An overview of the present state of the art in the different scientific and technological fields related to spaceborne imaging radars was presented. The data acquired with the SEASAT SAR (1978) and Shuttle Imaging Radar, SIR-A (1981) clearly demonstrated the important emphasis in the 80's is going to be on in-depth research investigations conducted with the more flexible and sophisticated SIR series instruments and on long term monitoring of geophysical phenomena conducted from free-flying platforms such as ERS-1 and RADARSAT.

  15. Spaceborne laser radar.

    NASA Technical Reports Server (NTRS)

    Flom, T.

    1972-01-01

    Development of laser systems to acquire and track targets in applications such as the rendezvous and docking of two spacecraft. A scan technique is described whereby a narrow laser beam is simultaneously scanned with an equally narrow receiver field-of-view without the aid of mechanical gimbals. Equations are developed in order to examine the maximum acquisition and tracking rates, and the maximum target range for a scanning laser radar system. A recently built prototype of a small, lightweight, low-power-consuming scanning laser radar is described.

  16. Microwave radar oceanographic investigations

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.

    1988-01-01

    The Radar Ocean Wave Spectrometer (ROWS) technique was developed and demonstrated for measuring ocean wave directional spectra from air and space platforms. The measurement technique was well demonstrated with data collected in a number of flight experiments involving wave spectral comparisons with wave buoys and the Surface Contour Radar (SCR). Recent missions include the SIR-B underflight experiment (1984), FASINEX (1986), and LEWEX (1987). ROWS related activity is presently concentrating on using the aircraft instrument for wave-processes investigations and obtaining the necessary support (consensus) for a satellite instrument development program. Prospective platforms include EOS and the Canadian RADARSAT.

  17. Radar Investigations of Asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    Radar investigations of asteroids, including observations during 1984 to 1985 of at least 8 potential targets and continued analyses of radar data obtained during 1980 to 1984 for 30 other asteroids is proposed. The primary scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements yield estimates of target size, shape, and spin vector; place constraints on topography, morphology, density, and composition of the planetary surface; yield refined estimates of target orbital parameters; and reveals the presence of asteroidal satellites.

  18. Thermal performance of an air solar collector with an absorber plate made of recyclable aluminum cans

    Microsoft Academic Search

    G. Alvarez; J. Arce; L. Lira; M. R. Heras

    2004-01-01

    The present paper describes the development and testing of an efficient single-glass air solar collector with an absorber plate made of recyclable aluminum cans (RAC). This collector was designed as a proposal to use recycle recyclable materials to build absorber plates of air solar collectors at an acceptable cost. The absorber plate of the collector consisted of eight circular cross

  19. Structural investigation and microwave characteristics of (Ba{sub 0.2}La{sub 0.8})Fe{sub 0.2}Mn{sub 0.4}Ti{sub 0.4}O{sub 3} absorbing materials

    SciTech Connect

    Manaf, Azwar [Dept. of Physics, Faculty of Mathematics and Natural Sciences, Indonesia of University (Indonesia); Adi, Wisnu Ari, E-mail: dwisnuaa@batan.go.id [Center for Technology of Nuclear Industry Material, National Nuclear Energy Agency (Indonesia)

    2014-03-24

    Synthesis and characterization of (Ba{sub 0.2}La{sub 0.8})Fe{sub 0.2}Mn{sub 0.4}Ti{sub 0.4}O{sub 3} absorbing material by mechanical alloying process has been performed. The absorbing material was prepared by oxide materials, namely BaCO{sub 3}, La{sub 2}O{sub 3}, TiO{sub 2}, Fe{sub 2}O{sub 3}, and MnCO{sub 3}. The mixture was milled for 10 h and then sintered at a temperature of 1000 ° C for 10 h. The refinement results of x-ray diffraction pattern of lanthanum manganite substituted with barium showed that the sample consisted of two phases, namely, La{sub 0.9125}MnO{sub 3} phase which has a structure monoclinic (I12/a1) with lattice parameters a = 5.527(1) Å, b = 5.572(1) Å and c = 7.810(1) Å, ? = ? = 90° and ? = 89.88(5)°, the unit cell volume of V = 240.57(8) Å{sup 3}, and the atomic density of ? = 6.238 gr.cm{sup ?3}. The microstructure analyses showed that the particle shapes was polygonal with the varied particle sizes of 1 ? 3 ?m distributed homogeneously on the surface of the samples. The results of the electromagnetic wave absorption curve analysis by using a vector network analyzer (VNA) showed that the sample can absorb microwaves in the frequency range of 8-15 GHz with a very wide absorption bandwidth. It indicates that the as prepared absorber presents potential absorbing property in X and Ku-band. We concluded that the (Ba{sub 0.2}La{sub 0.8})Fe{sub 0.2}Mn{sub 0.4}Ti{sub 0.4}O{sub 3} material can be applied as a candidate absorber material of microwaves or electromagnetic wave.

  20. [Osteosynthesis using absorbable implants].

    PubMed

    Arva, G; Fröhlich, P

    1994-01-01

    Authors report on one case of malleolar synthesis with the use of biodegradable implants. The advantages of the resorbing osteosynthesis materials and the possible complications are described. PMID:8162144

  1. Abbe's law, 210 absorbing media

    E-print Network

    Stanford University

    Index Abbe's law, 210 absorbing media apparent lack of energy conservation, 197--198 exceptions--199 absorbing medium, 193, 194 absorption coefficient, 195 absorption estimator, 47 acceptance probability, 336 distribution function, see BTDF birefringence, 20 black body, 179 Boltzmann equation, 23 boundary distance

  2. Energy absorber for the CETA

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  3. Unglazed transpired solar collector having a low thermal-conductance absorber

    DOEpatents

    Christensen, Craig B. (Boulder, CO); Kutscher, Charles F. (Golden, CO); Gawlik, Keith M. (Boulder, CO)

    1997-01-01

    An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprising an unglazed absorber formed of low thermal-conductance material having a front surface for receiving the solar radiation and openings in the unglazed absorber for passage of the incoming air such that the incoming air is heated as it passes towards the front surface of the absorber and the heated air passes through the openings in the absorber for distribution.

  4. Bistatic synthetic aperture radar

    Microsoft Academic Search

    A. M. Horne; G. Yates

    2002-01-01

    Synthetic aperture radar (SAR) is becoming increasingly important in many military ground surveillance and targeting roles because of its ability to operate in all weather, day and night, and to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and receiver are on separate platforms, is seen as a potential means of countering vulnerability. This

  5. Rain radar instrument definition

    NASA Astrophysics Data System (ADS)

    Vincent, Nicolas; Chenebault, J.; Suinot, Noel; Mancini, Paolo L.

    1996-12-01

    As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of instrument concepts associated with rain rate retrieval algorithms in order to select the most performing one. Several trade-off analysis at subsystem level leads then to the definition of the proposed design. In particular, as pulse compression is implemented in order to increase the radar sensitivity, the selected method to achieve a pulse response with a side-lobe level below--60 dB is presented. Antenna is another critical rain radar subsystem and several designs are com pared: direct radiating array, single or dual reflector illuminated by single or dual feed arrays. At least, feasibility of centralized amplification using TWTA is compared with criticality of Tx/Rx modules for distributed amplification. Mass and power budgets of the designed instrument are summarized as well as standard deviations and bias of simulated rain rate retrieval profiles. The feasibility of a compliant rain radar instrument is therefore demonstrated.

  6. Bistatic radar meteorological satellite

    NASA Technical Reports Server (NTRS)

    Nathanson, F. E.

    1981-01-01

    A technique is discussed that employs a radar transmitter with a moderate size antenna placed in a geosynchronous orbit with either a 0 degree or a low inclination orbit. The reflected signals from the precipitation are then received either on a single beam from a satellite having a beamwidth of about 6 degrees or preferably with a beam that scans the U.S. in a raster pattern with about 0.9 degrees beamwidth. While it would seem that a bistatic system with the transmitter at synchronous altitude and the receivers near the surface would not be a very efficient way of designing a radar system, it is somewhat surprising that the required power and antenna sizes are not that great. Two factors make the meteorological application somewhat more attractive than the bistatic detection of point targets. First, the bistatic reflections of radar signals from precipitation are to a large extent omnidirectional, and while raindrops are spheriods rather than spheres, the relationship of the reflectivity of the rain to rainfall rate can be easily derived. The second reason is that the rain echo signal level is independent of range from a receive only radar, and if the bistatic system works at all, it will work at long ranges.

  7. Weather and radar interactions

    Microsoft Academic Search

    J. P. Booth

    2005-01-01

    This paper discusses the effects of weather on radar system performance. This discussion were based on computer simulations and climatological data. The relationships between frequency and range were explored as they interact with the weather. This effort is being conducted in the RF Technology Division of the Applied Sensors, Guidance, and Electronics Directorate, US Army Aviation and Missile Research, Development,

  8. Distributed aperture OFDM radar

    Microsoft Academic Search

    Byung Wook Jung; R aviraj S. Adve; Joohwan Chun

    2009-01-01

    This paper presents a new method of obtaining frequency diversity using orthogonal frequency division multiplexing (OFDM). Exploiting spatial diversity, the key advantage of a distributed aperture radar, requires orthogonality in, for example, the frequency, time, waveform, dimensions across sensors. This paper focuses on the simplest of these cases; frequency orthogonality. Here we address the key drawback associated with frequency diversity:

  9. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  10. Energy deposition studies for the LBNE beam absorber

    E-print Network

    Rakhno, Igor L; Tropin, Igor S

    2015-01-01

    Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system -- all with corresponding radiation shielding -- was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

  11. Determination of Seabird Density using Marine Radar Robert McFarlane* & James Lester

    E-print Network

    Holberton, Rebecca L.

    Conservation Office of Texas, were to: (1) determine the efficacy of marine radar for observing coastal birdsFarlane & Associates, 2604 Mason St., Houston, Texas 77006-3116, USA, Email: rwmcf@swbell.net The upper coast of Texas water because water absorbs, rather than reflects, laser beams. Visual counts are limited to daylight

  12. Impedance matched thin metamaterials make metals absorbing

    NASA Astrophysics Data System (ADS)

    Mattiucci, N.; Bloemer, M. J.; Aközbek, N.; D'Aguanno, G.

    2013-11-01

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin (<1 micron), polarization independent, extremely efficient absorbers (in principle being capable to reach A > 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  13. Imaging highly absorbing nanoparticles using photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Lussier, Simon-Alexandre; Moradi, Hamid; Price, Alain; Murugkar, Sangeeta

    2015-03-01

    Gold nanoparticles (NPs) have tremendous potential in biomedicine. They can be used as absorbing labels inside living cells for the purpose of biomedical imaging, biosensing as well as for photothermal therapy. We demonstrate photothermal imaging of highly-absorbing particles using a pump-probe setup. The photothermal signal is recovered by heterodyne detection, where the excitation pump laser is at 532 nm and the probe laser is at 638 nm. The sample is moved by a scanning stage. Proof of concept images of red polystyrene microspheres and gold nanoparticles are obtained with this home-built multimodal microscope. The increase in temperature at the surface of the gold NPs, due to the pump laser beam, can be directly measured by means of this photothermal microscope and then compared with the results from theoretical predictions. This technique will be useful for characterization of nanoparticles of different shapes, sizes and materials that are used in cancer diagnosis and therapy.

  14. Optimization of the acoustic absorption coefficients of certain functional absorbents

    NASA Technical Reports Server (NTRS)

    Pocsa, V.; Biborosch, L.; Veres, A.; Halpert, E.; Lorian, R.; Botos, T.

    1974-01-01

    The sound absorption coefficients of some functional absorbents (mineral wool plates) are determined by the reverberation chamber method. The influence of the angle of inclination of the sound absorbing material with respect to the surface to be treated is analyzed as well as the influence of the covering index, defined as the ratio of the designed area of a plate and the area of the treated surface belonging to another plate. As compared with the conventional method of applying sound-absorbing plates, the analyzed structures have a higher technological and economical efficiency. The optimum structure corresponds to an angle of inclination of 15 deg and a covering index of 0.8.

  15. METR 4624--Radar Meteorology SPRING 2012

    E-print Network

    Droegemeier, Kelvin K.

    METR 4624--Radar Meteorology SPRING 2012 Dr. Michael I. Biggerstaff; drdoppler@ou.edu (best method Principles of weather radar and storm observations including: radar system design, em wave propagation, radar&Q, moments of the power spectrum, ground clutter, attenuation, rainfall measurements using radar reflectivity

  16. METR 4624--Radar Meteorology SPRING 2014

    E-print Network

    Droegemeier, Kelvin K.

    METR 4624--Radar Meteorology SPRING 2014 Dr. Michael I. Biggerstaff; drdoppler@ou.edu (best method Principles of weather radar and storm observations including: radar system design, em wave propagation, radar&Q, moments of the power spectrum, ground clutter, attenuation, rainfall measurements using radar reflectivity

  17. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater spectral efficiency than the MSK waveform, such as linear frequency modulation (LFM) and Costas frequency hopping, have a fixed peak sidelobe level that is therefore not configurable, and can be exceeded by high contrast targets. Furthermore, in the case of a multistatic experiment observing a target in motion, self-interference from the transmitter to the receiver is mitigated by the MSK waveform. Waveforms that have delay Doppler coupling, such as LFM, provide no such protection.

  18. Radar images of Mars

    NASA Technical Reports Server (NTRS)

    Muhleman, Duane O.; Butler, Bryan J.; Grossman, Arie W.; Slade, Martin A.

    1991-01-01

    VLA radar-reflected flux-density mappings have yielded full disk images of Mars which reveal near-surface features, including a region in the Tharsis volcano area that displayed no echo to the very low level of the radar-system noise. This feature is interpreted as a deposit of dust or ash whose density is less than about 0.5 g/cu cm; it must be several meters thick, and may be much deeper. The most strongly reflecting geological feature was the south polar ice cap, which is interpretable as arising from nearly-pure CO2 or H2O ice, with less than 2 vol pct Martian dust. Only one anomalous reflecting feature was identified outside the Tharsis region.

  19. New weather radar coming

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    What would you call the next generation of radar for severe weather prediction? NEXRAD, of course. A prototype for the new system was recently completed in Norman, Okla., and by the early 1990s up to 195 stations around the United States will be tracking dangerous weather and sending faster, more accurate, and more detailed warnings to the public.NEXRAD is being built for the Departments of Commerce, Transportation, and Defense by the Unisys Corporation under a $450 million contract signed in December 1987. Th e system will be used by the National Weather Service, the Federal Aviation Administration (FAA), and the U.S. Air Force and Navy. The NEXRAD radar tower in Norman is expected to be operational in October.

  20. Absorbing WIPP brines : a TRU waste disposal strategy.

    SciTech Connect

    Yeamans, D. R. (David R.); Wright, R. (Robert)

    2002-01-01

    Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250-liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WlPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent would still function normally at that pressure and would not degrade in the approximately 5e-4 Sv/hr radioactive field produced by the waste. Heat generation from the absorption was minimal. The in situ absorption created a single waste stream of 8 SWBs whereas the least complicated alternate method of disposal would have yielded at least an additional 2600 liters of mixed low level liquid waste plus about two cubic meters of mixed low level solid waste, and would have resulted in higher risk of radiation exposure to workers. The in situ absorption saved $3 1 lk in a combination of waste treatment, disposal, material and personnel costs compared to the least expensive alternative and $984k compared to the original plan.

  1. ABSORBING WIPP BRINES: A TRU WASTE DISPOSAL STRATEGY

    SciTech Connect

    Yeamans, D. R.; Wrights, R. S.

    2002-02-25

    Los Alamos National Laboratory (LANL) has completed experiments involving 15 each, 250- liter experimental test containers of transuranic (TRU) heterogeneous waste immersed in two types of brine similar to those found in the underground portion of the Waste Isolation Pilot Plant (WIPP). To dispose of the waste without removing the brine from the test containers, LANL added commercially available cross-linked polyacrylate granules to absorb the 190 liters of brine in each container, making the waste compliant for shipping to the WIPP in a Standard Waste Box (SWB). Prior to performing the absorption, LANL and the manufacturer of the absorbent conducted laboratory and field tests to determine the ratio of absorbent to brine that would fully absorb the liquid. Bench scale tests indicated a ratio of 10 parts Castile brine to one part absorbent and 6.25 parts Brine A to one part absorbent. The minimum ratio of absorbent to brine was sought because headspace in the containers was limited. However, full scale testing revealed that the ratio should be adjusted to be about 15% richer in absorbent. Additional testing showed that the absorbent would not apply more than 13.8 kPa pressure on the walls of the vessel and that the absorbent would still function normally at that pressure and would not degrade in the approximately 5e-4 Sv/hr radioactive field produced by the waste. Heat generation from the absorption was minimal. The in situ absorption created a single waste stream of 8 SWBs whereas the least complicated alternate method of disposal would have yielded at least an additional 2600 liters of mixed low level liquid waste plus about two cubic meters of mixed low level solid waste, and would have resulted in higher risk of radiation exposure to workers. The in situ absorption saved $311k in a combination of waste treatment, disposal, material and personnel costs compared to the least expensive alternative and $984k compared to the original plan.

  2. Cognitive processing for nonlinear radar

    NASA Astrophysics Data System (ADS)

    Martone, Anthony; Ranney, Kenneth; Hedden, Abigail; Mazzaro, Gregory; McNamara, David

    2013-05-01

    An increasingly cluttered electromagnetic environment (EME) is a growing problem for radar systems. This problem is becoming critical as the available frequency spectrum shrinks due to growing wireless communication device usage and changing regulations. A possible solution to these problems is cognitive radar, where the cognitive radar learns from the environment and intelligently modifies the transmit waveform. In this paper, a cognitive nonlinear radar processing framework is introduced where the main components of this framework consist of spectrum sensing processing, target detection and classification, and decision making. The emphasis of this paper is to introduce a spectrum sensing processing technique that identifies a transmit-receive frequency pair for nonlinear radar. It will be shown that the proposed technique successfully identifies a transmit-receive frequency pair for nonlinear radar from data collected from the EME.

  3. A review of array radars

    NASA Astrophysics Data System (ADS)

    Brookner, E.

    1981-10-01

    Achievements in the area of array radars are illustrated by such activities as the operational deployment of the large high-power, high-range-resolution Cobra Dane; the operational deployment of two all-solid-state high-power, large UHF Pave Paws radars; and the development of the SAM multifunction Patriot radar. This paper reviews the following topics: array radars steered in azimuth and elevation by phase shifting (phase-phase steered arrays); arrays steered + or - 60 deg, limited scan arrays, hemispherical coverage, and omnidirectional coverage arrays; array radars steering electronically in only one dimension, either by frequency or by phase steering; and array radar antennas which use no electronic scanning but instead use array antennas for achieving low antenna sidelobes.

  4. Outline of the Mu radar

    NASA Technical Reports Server (NTRS)

    Kato, S.

    1983-01-01

    A middle and upper atmospheric radar system is described. The antenna array consists of 25 groups each of which consists of 19 crossed-Yagis with three elements; each antenna has semiconductor transmitter and receiver, called a module, and each group of 19 antennas works as an independent small radar steering its radar beam under the control of a microcomputer. Thus, the total system consists of 25 small radars of this kind, enabling one to do various sophisticated operations with the system. The system is controlled by two other computers, one for radar controlling (HP9835A) and the other for data taking and on-line analysis (VAX11/750). The computer-controlled system is simple in operation for users and reliable in observation. Very quick beam steering (as quick as in a msec) is also possible because of electronic phase-changing of each module output under control of the microcomputer which is further controlled by the radar controller.

  5. Airborne bistatic radar applications

    Microsoft Academic Search

    James A. Foster

    1987-01-01

    Applications of bistatic radar when one or both of the units are airborne are discussed. Scenarios that merit deeper consideration are covert strike and head-on SAR using a stand-off illuminator, either airborne or space-based; area air defense with passive ground-based receivers and stand-off illuminators; an airborne picket line to detect stealth aircraft and missiles; AWACS aircraft providing mutual support in

  6. Radar receiver procedures

    NASA Astrophysics Data System (ADS)

    1990-04-01

    This International Test Operations Procedures (ITOP) outlines the test methods used in evaluating the performance and characteristics of general types of radar receivers to include single or variable frequency receivers. The test methods serve as a guide in determining the overall efficiency of such equipment as a function of their design and their recorded performance. If a conflict exists between the accuracies, frequency, and levels stated in this ITOP and those stated in the appropriate requirements documents, the requirements documents must be used.

  7. Imaging synthetic aperture radar

    DOEpatents

    Burns, Bryan L. (Tijeras, NM); Cordaro, J. Thomas (Albuquerque, NM)

    1997-01-01

    A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

  8. Shuttle imaging radar experiment

    USGS Publications Warehouse

    Elachi, C.; Brown, W.E.; Cimino, J.B.; Dixon, T.; Evans, D.L.; Ford, J.P.; Saunders, R.S.; Breed, C.; Masursky, H.; McCauley, J.F.; Schaber, G.; Dellwig, L.; England, A.; MacDonald, H.; Martin-Kaye, P.; Sabins, F.

    1982-01-01

    The shuttle imaging radar (SIR-A) acquired images of a variety of the earth's geologic areas covering about 10 million square kilometers. Structural and geomorphic features such as faults, folds, outcrops, and dunes are clearly visible in both tropical and arid regions. The combination of SIR-A and Seasat images provides additional information about the surface physical properties: topography and roughness. Ocean features were also observed, including large internal waves in the Andaman Sea. Copyright ?? 1982 AAAS.

  9. Packed Alumina Absorbs Hypergolic Vapors

    NASA Technical Reports Server (NTRS)

    Thomas, J. J.; Mauro, D. M.

    1984-01-01

    Beds of activated alumina effective as filters to remove hypergolic vapors from gas streams. Beds absorb such substances as nitrogen oxides and hydrazines and may also absorb acetylene, ethylene, hydrogen sulfide, benzene, butadiene, butene, styrene, toluene, and xoylene. Bed has no moving parts such as pumps, blowers and mixers. Reliable and energy-conservative. Bed readily adapted to any size from small portable units for use where little vapor release is expected to large stationary units for extensive transfer operations.

  10. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, W.H.

    1984-10-16

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system. 9 figs.

  11. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, William H. (Columbus, OH)

    1984-01-01

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

  12. Radar gun hazards

    SciTech Connect

    Not Available

    1991-12-20

    Radar guns - hand-held units used by the law to nail speeders - have been in use since the early '60s. Now they've been accused of causing cancer. Police officers in several states have so far filed eight suits against the manufacturer, claiming that they have contracted rare forms of cancer, such as of the eyelid and the testicle, from frequent proximity to the devices. Spurred by concerns expressed by police groups, researchers at the Rochester Institute of Technology are conducting what they believe to be the first research of its kind in the nation. Last month psychologist John Violanti, an expert in policy psychology and health, sent out a one-page survey to 6,000 active and retired police officers in New York State, asking them about their health and their use of radar guns. Violanti says melanoma, leukemia, and lymph node cancer may be linked to these as well as other electromagnetic devices. The Food and Drug Administration earlier this year issued a warning about radar guns, telling users not to operate them closer than 6 inches from the body. But this may not be a sufficient safeguard since the instruments can give off crisscrossing wave emissions within a police vehicle. The survey will be used to help determine if it would be safer to mount the guns, which are currently either hand-held or mounted on dashboards, outside troopers' cars.

  13. Spaceborne Imaging Radar Project

    NASA Technical Reports Server (NTRS)

    Herman, Neil

    1986-01-01

    In June of 1985 the Project Initiation Agreement was signed by the Jet Propulsion Laboratory and the NASA Office of Space Science and Applications for the Spaceborne Imaging Radar Project (SIR). The thrust of the Spaceborne Imaging Radar Project is to continue the evolution of synthetic aperture radar (SAR) science and technology developed during SEASAT, SIR-A and SIR-B missions to meet the needs of the Earth Observing System (EOS) in the mid 1990's. As originally formulated, the Project plans were for a reflight of the SIR-B in 1987, the development of a new SAR, SIR-C, for missions in mid 1989 and early 1990, and the upgrade of SIR-C to EOS configuration with a qualification flight aboard the shuttle in the 1993 time frame (SIR-D). However, the loss of the shuttle Challenger has delayed the first manifest for SIR to early 1990. This delay prompted the decision to drop SIR-B reflight plans and move ahead with SIR-C to more effectively utilize this first mission opportunity. The planning for this project is discussed.

  14. The Shuttle Radar Topography Mission

    NASA Astrophysics Data System (ADS)

    Farr, Tom G.; Rosen, Paul A.; Caro, Edward; Crippen, Robert; Duren, Riley; Hensley, Scott; Kobrick, Michael; Paller, Mimi; Rodriguez, Ernesto; Roth, Ladislav; Seal, David; Shaffer, Scott; Shimada, Joanne; Umland, Jeffrey; Werner, Marian; Oskin, Michael; Burbank, Douglas; Alsdorf, Douglas

    2007-06-01

    The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution. Details of the development, flight operations, data processing, and products are provided for users of this revolutionary data set.

  15. Space-based radar handbook

    Microsoft Academic Search

    Leopold J. Cantafio

    1989-01-01

    The design and operation of space-based radar (SBR) systems are discussed in chapters contributed by leading experts. An overview of current and planned SBRs is presented, and particular attention is given to SBR-platform orbits, the ionospheric environment and its effects on SBR detection, space-based SARs, bistatic SBRs, rendezvous radars, radar altimeters for space vehicles, scatterometers and other modest-resolution systems, and

  16. Radar-aeolian roughness project

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

    1991-01-01

    The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

  17. Overview of Radar Data Compression Valliappa Lakshmanan

    E-print Network

    Lakshmanan, Valliappa

    Overview of Radar Data Compression Valliappa Lakshmanan Cooperative Institute of Mesoscale Meteorological Studies University of Oklahoma & National Severe Storms Laboratory Abstract Radar data is routinely transmitted in real-time from the coterminous United States (CONUS) radar sites and placed

  18. REVIEW ARTICLE Interferometric Synthetic Aperture Radar

    E-print Network

    Kansas, University of

    REVIEW ARTICLE Interferometric Synthetic Aperture Radar Christopher T. Allen Department of Electrical Engineering and Computer Science and Radar Systems and Remote Sensing Laboratory University of Kansas Abstract. This paper provides a brief review of interferometric synthetic aperture radar (In

  19. Solid-state radar transmitters

    NASA Astrophysics Data System (ADS)

    Ostroff, E. D.; Borkowski, M.; Thomas, H.; Curtis, J.

    The technology and design procedures for introducing transistors into radio transmitters are discussed. The design characteristics of solid-state radar transmitters are described, with emphasis given to power amplifier/modules and devices for summing the output power in space or in an output combiner. Some design issues related to power supplies, pulse waveform amplitude regulation; reliability; and cost; and also considered. Some examples of successful solid-state radar systems are described, including the AN/TPS-59 radar, the AN/SPS-40 system, and the Pave/PAWS phased array radar. Black and white photographs of the different systems are provided.

  20. Radar data processing and analysis

    NASA Technical Reports Server (NTRS)

    Ausherman, D.; Larson, R.; Liskow, C.

    1976-01-01

    Digitized four-channel radar images corresponding to particular areas from the Phoenix and Huntington test sites were generated in conjunction with prior experiments performed to collect X- and L-band synthetic aperture radar imagery of these two areas. The methods for generating this imagery are documented. A secondary objective was the investigation of digital processing techniques for extraction of information from the multiband radar image data. Following the digitization, the remaining resources permitted a preliminary machine analysis to be performed on portions of the radar image data. The results, although necessarily limited, are reported.

  1. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  2. Radar Image, Hokkaido, Japan

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The southeast part of the island of Hokkaido, Japan, is an area dominated by volcanoes and volcanic caldera. The active Usu Volcano is at the lower right edge of the circular Lake Toya-Ko and near the center of the image. The prominent cone above and to the left of the lake is Yotei Volcano with its summit crater. The city of Sapporo lies at the base of the mountains at the top of the image and the town of Yoichi -- the hometown of SRTM astronaut Mamoru Mohri -- is at the upper left edge. The bay of Uchiura-Wan takes up the lower center of the image. In this image, color represents elevation, from blue at the lowest elevations to white at the highest. The radar image has been overlaid to provide more details of the terrain. Due to a processing problem, an island in the center of this crater lake is missing and will be properly placed when further SRTM swaths are processed. The horizontal banding in this image is a processing artifact that will be removed when the navigation information collected by SRTM is fully calibrated. This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 100 by 150 kilometers (62 by 93 miles) Location: 42.5 deg. North lat., 140.3 deg. East lon. Orientation: North towards upper left Image Data: SRTM Original Data Resolution: SRTM 30 meters (99 feet) Date Acquired: February 17, 2000

  3. Millimeter Wave Cloud Radar (MMCR) Handbook

    SciTech Connect

    KB Widener; K Johnson

    2005-01-30

    The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

  4. Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

    PubMed Central

    Grant, James P.; McCrindle, Iain J.H.; Cumming, David R.S.

    2012-01-01

    Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ ?/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems. PMID:23299442

  5. Infrared Imaging Video Bolometer with a Double Layer Absorbing Foil

    NASA Astrophysics Data System (ADS)

    Miroshnikov, Igor V.; Kostryukov, Artem Y.; Peterson, Byron J.

    The object of the present paper is an infrared video bolometer with a bolometer foil consisting of two layers: the first layer is constructed of radiation absorbing blocks and the second layer is a thermal isolating base. The absorbing blocks made of a material with a high photon attenuation coefficient (gold) were spatially separated from each other while the base should be made of a material having high tensile strength and low thermal conductance (stainless steel). Such a foil has been manufactured in St. Petersburg and calibrated in NIFS using a vacuum test chamber and a laser beam as an incident power source. A finite element method (FEM) code was applied to simulate the thermal response of the foil. Simulation results are in good agreement with the experimental calibration data. The temperature response of the double layer foil is a factor of two higher than that of a single foil IR video bolometer using the same absorber material and thickness.

  6. Removing interfering clutter associated with radar pulses that an airborne radar receives from a radar transponder

    DOEpatents

    Ormesher, Richard C. (Albuquerque, NM); Axline, Robert M. (Albuquerque, NM)

    2008-12-02

    Interfering clutter in radar pulses received by an airborne radar system from a radar transponder can be suppressed by developing a representation of the incoming echo-voltage time-series that permits the clutter associated with predetermined parts of the time-series to be estimated. These estimates can be used to estimate and suppress the clutter associated with other parts of the time-series.

  7. Planetary radar studies. [radar mapping of the Moon and radar signatures of lunar and Venus craters

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Cutts, J. A.

    1981-01-01

    Progress made in studying the evolution of Venusian craters and the evolution of infrared and radar signatures of lunar crater interiors is reported. Comparison of radar images of craters on Venus and the Moon present evidence for a steady state Venus crater population. Successful observations at the Arecibo Observatory yielded good data on five nights when data for a mix of inner and limb areas were acquired. Lunar craters with radar bright ejects are discussed. An overview of infrared radar crater catalogs in the data base is included.

  8. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  9. Parallel-Plate Acoustic Absorbers For Hot Environments

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph; Parrot, Tony L.

    1995-01-01

    Stacking patterns and materials chosen to suppress noise. Acoustic liners incorporating parallel-plate absorbing elements proposed for use in suppressing broadband aerodynamic noise originating in flows of hot gases in ducts. One potential application lies in suppressing noise generated in exhaust-jet mixer/ejectors in propulsion system of proposed High-Speed Civil Transport. In addition, such absorbers useful in any situation in which high temperature limits use of such conventional resonant acoustic-liner materials as perforated face sheets bonded to honey-comb-core panels.

  10. Imaging Radar for Ecosystem Studies

    NASA Technical Reports Server (NTRS)

    Waring, Richard H.; Way, JoBea; Hunt, E. Raymond J.; Morrissey, Leslie; Ranson, K. Jon; Weishampel, John F.; Oren, Ram; Franklin, Steven E.

    1996-01-01

    Recently a number of satellites have been launched with radar sensors, thus expanding opportunities for global assessment. In this article we focus on the applications of imaging radar, which is a type of sensor that actively generates pulses of microwaves and, in the interval between sending pulses, records the returning signals reflected back to an antenna.

  11. Rendezvous radar for orbital vehicles

    Microsoft Academic Search

    John W. Locke; Larry D. Casey

    1992-01-01

    In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of

  12. OFDM waveforms for multistatic radars

    Microsoft Academic Search

    Y. Paichard

    2010-01-01

    In this paper, the benefits of OFDM waveforms are analyzed for multistatic radar systems, where several radar stations cooperate in the same frequency band. The signal is coded over a 2D pattern, in the time and the frequency domains, using orthogonal Golay complementary sets derived from Reed-Muller codes. Binary data are also encoded in the signal. The obtained ambiguity and

  13. Frequency diversity in multistatic radars

    Microsoft Academic Search

    Byung Wook Jung; R aviraj S. Adve; Joohwan Chun

    2008-01-01

    This paper presents the model and analysis of a frequency-diverse radar system. Multistatic radar systems provide an inherent spatial diversity by processing signals from different platforms which view a potential target from different aspect angles. By using different frequencies at each platform, an additional diversity gain can be obtained on top of the advantages of spatial diversity. Here, since platforms

  14. Classification algorithms for weather radar

    Microsoft Academic Search

    Felix Yanovsky; Vitaly Marchuk; Yaroslav Ostrovsky; Yulia Averyanova

    2008-01-01

    Theory, measurements, and signal processing applying to the radar remote sensing of weather objects are considered. Algorithms for hydrometeor type and turbulence intensity recognition are developed and analyzed. Particularly, fuzzy logic and neural network approaches are applied for weather radar signal processing.

  15. Space Radar Images of Earth

    NSDL National Science Digital Library

    This collection of images was captured by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar, which was flown on two flights of the space shuttle Endeavour in 1994. Images are classified into categories for ease in searching: archaeological sites, cities, ecology and agriculture, geology, interferometry, oceans, rivers, snow and ice, and volcanoes.

  16. Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles: II. A Study of Three Radars with Different Sensitivity

    NASA Astrophysics Data System (ADS)

    Janches, D.; Swarnalingam, N.; Plane, J. M. C.; Nesvorný, D.; Feng, W.; Vokrouhlický, D.; Nicolls, M. J.

    2015-07-01

    The sensitivity of radar systems to detect different velocity populations of the incoming micrometeoroid flux is often the first argument considered to explain disagreements between models of the Near-Earth dust environment and observations. Recently, this was argued by Nesvorný et al. to support the main conclusions of a Zodiacal Dust Cloud (ZDC) model which predicts a flux of meteoric material into the Earth’s upper atmosphere mostly composed of small and very slow particles. In this paper, we expand on a new methodology developed by Janches et al. to test the ability of powerful radars to detect the meteoroid populations in question. In our previous work, we focused on Arecibo 430 MHz observations since it is the most sensitive radar that has been used for this type of observation to date. In this paper, we apply our methodology to two other systems, the 440 MHz Poker Flat Incoherent Scatter Radar and the 46.5 Middle and Upper Atmosphere radar. We show that even with the less sensitive radars, the current ZDC model over-predicts radar observations. We discuss our results in light of new measurements by the Planck satellite which suggest that the ZDC particle population may be characterized by smaller sizes than previously believed. We conclude that the solution to finding agreement between the ZDC model and sensitive high power and large aperture meteor observations must be a combination of a re-examination not only of our knowledge of radar detection biases, but also the physical assumptions of the ZDC model itself.

  17. A radar image time series

    NASA Technical Reports Server (NTRS)

    Leberl, F.; Fuchs, H.; Ford, J. P.

    1981-01-01

    A set of ten side-looking radar images of a mining area in Arizona that were aquired over a period of 14 yr are studied to demonstrate the photogrammetric differential-rectification technique applied to radar images and to examine changes that occurred in the area over time. Five of the images are rectified by using ground control points and a digital height model taken from a map. Residual coordinate errors in ground control are reduced from several hundred meters in all cases to + or - 19 to 70 m. The contents of the radar images are compared with a Landsat image and with aerial photographs. Effects of radar system parameters on radar images are briefly reviewed.

  18. Space-based radar handbook

    NASA Astrophysics Data System (ADS)

    Cantafio, Leopold J.

    The design and operation of space-based radar (SBR) systems are discussed in chapters contributed by leading experts. An overview of current and planned SBRs is presented, and particular attention is given to SBR-platform orbits, the ionospheric environment and its effects on SBR detection, space-based SARs, bistatic SBRs, rendezvous radars, radar altimeters for space vehicles, scatterometers and other modest-resolution systems, and thermal control for SBRs. Also considered are the radar cross sections of satellites and other space targets, SBR clutter and interference, space antenna technology, onboard radar-signal processors, space power systems, and SBR structures. Diagrams, drawings, graphs, maps, and tables of numerical data are provided.

  19. Radar image registration and rectification

    NASA Technical Reports Server (NTRS)

    Naraghi, M.; Stromberg, W. D.

    1983-01-01

    Two techniques for radar image registration and rectification are presented. In the registration method, a general 2-D polynomial transform is defined to accomplish the geometric mapping from one image into the other. The degree and coefficients of the polynomial are obtained using an a priori found tiepoint data set. In the second part of the paper, a rectification procedure is developed that models the distortion present in the radar image in terms of the radar sensor's platform parameters and the topographic variations of the imaged scene. This model, the ephemeris data and the digital topographic data are then used in rectifying the radar image. The two techniques are then used in registering and rectifying two examples of radar imagery. Each method is discussed as to its benefits, shortcomings and registration accuracy.

  20. Cassini RADAR at Titan : Results in 2014/2015

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.

    2015-04-01

    Since the last EGU meeting, two Cassini flybys of Titan will have featured significant RADAR observations, illuminating our understanding of this enigmatic, complex world and its hydrocarbon seas in particular. T104, which executed in August 2014, featured a nadir-pointed altimetry swath over the northern part of Kraken Mare, Titan's largest sea. The echo characteristics showed that the sea surface was generally flat (to within a few mm), although a couple of areas appear to show some evidence of roughness. Intriguingly, altimetry processing which yielded (Mastrogiuseppe et al., GRL, 2014) the detection of a prominent bottom echo 160m beneath the surface of Ligeia Mare on T91 failed to yield a similar echo over most of Kraken on T104, suggesting either that Kraken is very deep (perhaps consistent with rather steep shoreline topography) or that the liquid in Kraken is more radar-absorbing than that in Ligeia, or both. The absorbing-liquid scenario may be consistent with a hydrological model for Titan's seas (Lorenz, GRL, 2014) wherein the most northerly seas receive more 'fresh' methane input, flushing ethane and other lower-volatility (and more radar-absorbing) solutes south into Kraken. T108, the last northern seas radar observation until T126 at the very end of the Cassini tour in 2017, is planned to execute on 11th January 2015, and preliminary results will be presented at the EGU meeting. This flyby features altimetry over part of Punga Mare, which will provide surface roughness information and possible bathymetry, permitting comparison of nadir-pointed data over all of Titan's three seas (Ligeia on T91; Kraken Mare on T104). The flyby also includes SAR observation of the so-called Ligeia 'Magic Island', the best-observed of several areas of varying radar brightness on Titan's seas. This brightness may be due to sediments suspended by currents, or by roughening of the surface either by local wind stress ('catspaw') or non-local stress (wind-driven currents). SAR imaging and altimetry over land areas on T104 and T108 will be reviewed (current flybys devote more close-approach time to altimetry, in part because of solar heating pointing constraints for other Cassini instruments), and selected interpretations and products of earlier coverage will be discussed.

  1. Waveform-dependent absorbing metasurfaces

    E-print Network

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  2. Waveform-dependent absorbing metasurfaces.

    PubMed

    Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2013-12-13

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW's), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications. PMID:24483674

  3. Waveform-Dependent Absorbing Metasurfaces

    NASA Astrophysics Data System (ADS)

    Wakatsuchi, Hiroki; Kim, Sanghoon; Rushton, Jeremiah J.; Sievenpiper, Daniel F.

    2013-12-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high-power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high-power pulses but not for high-power continuous waves (CW’s), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e., CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  4. SMAP Radar Processing and Expected Performance

    NASA Astrophysics Data System (ADS)

    West, R. D.; Jaruwatanadilok, S.

    2011-12-01

    This presentation will describe the processing algorithms being developed for the Soil Moisture Active Passive (SMAP) radar data and the expected characteristics of the measured backscattering cross sections. The SMAP radar combines some unique features such as a conically scanned antenna with SAR processing of the data. The rapidly varying squint angle gives the measurements variable resolution and noise characteristics and poses a challenge to the processor to maintain accuracy around the wide (1000 km) swath. Rapid variation of Doppler around the scan leads to a time domain azimuth correlation algorithm, and variation of the Doppler geometry will likely require varying the processing bandwidth to manage ambiguity contamination errors. The basic accuracy requirement is 1-dB (one-sigma) in the backscatter measurements at a resolution of 3 km. The main error contributions come from speckle noise, calibration uncertainty, and radio frequency interference (RFI). Speckle noise is determined by system design parameters and details of the processing algorithms. The calibration of the backscatter measurements will be based on pre-launch characterization of the radar components which allow corrections for short term (~1 month) variations in performance. Longer term variations and biases will be removed using measurements of stable reference targets such as parts of the Amazon rain forest, and possibly the oceans and ice sheets. RFI survey measurements will be included to measure the extent of RFI around the world. The SMAP radar is designed to be able to hop the operating frequency within the 80 MHz allocated band to avoid the worst RFI emitters. Data processing will detect and discard further RFI contaminated measurements. This work is supported by the SMAP project at JPL - CalTech. The SMAP mission has not been formally approved by NASA. The decision to proceed with the mission will not occur until the completion of the National Environmental Policy Act (NEPA) process. Material in this document related to SMAP is for information purposes only.

  5. Coherent backscatter and the radar characteristics of outer planet satellites

    NASA Technical Reports Server (NTRS)

    Hapke, Bruce

    1990-01-01

    It is presently suggested that the diffuse component-dominated high radar reflectivities and large polarization of Europa, Ganymede, and Callisto could be due to the illumination by a collimated source of a weakly absorbing particulate medium in which wavelength-scaled scatterers are separated by distances somewhat larger than the wavelength. A plausible medium could be a regolith composed of voids and/or silicate rocks imbedded in an icy matrix; multiply-scattered parts of the wavefront traversing the same path in opposite directions combine coherently in the backscatter direction to generate increased intensity, and the enhancement is different for the two components of polarized reflected radiation.

  6. Porous Carbon Nanoparticle Networks with Tunable Absorbability

    PubMed Central

    Dai, Wei; Kim, Seong Jin; Seong, Won-Kyeong; Kim, Sang Hoon; Lee, Kwang-Ryeol; Kim, Ho-Young; Moon, Myoung-Woon

    2013-01-01

    Porous carbon materials with high specific surface areas and superhydrophobicity have attracted much research interest due to their potential application in the areas of water filtration, water/oil separation, and oil-spill cleanup. Most reported superhydrophobic porous carbon materials are fabricated by complex processes involving the use of catalysts and high temperatures but with low throughput. Here, we present a facile single-step method for fabricating porous carbon nanoparticle (CNP) networks with selective absorbability for water and oils via the glow discharge of hydrocarbon plasma without a catalyst at room temperature. Porous CNP networks were grown by the continuous deposition of CNPs at a relatively high deposition pressure. By varying the fluorine content, the porous CNP networks exhibited tunable repellence against liquids with various degrees of surface tension. These porous CNP networks could be applied for the separation of not only water/oil mixtures but also mixtures of liquids with different surface tension levels. PMID:23982181

  7. An improved radar detection range plotting method based on radar equation

    Microsoft Academic Search

    Li-Wei Wang; Xiao-Song Jiang

    2011-01-01

    In this paper, an improved radar detection range plotting method based on radar equation is proposed. Radar equation can be used to plot the radar detection range in theory from the point of view of energy. But in practice, the condition can not be satisfied. Based on radar equation, this method takes ground reflection, atmospheric refraction, earth curvature and obstacle

  8. Understanding Radar Refractivity: Sources of Uncertainty

    E-print Network

    Droegemeier, Kelvin K.

    Understanding Radar Refractivity: Sources of Uncertainty David Bodine1,2 , Dan Michaud1,2 , Robert Radar Research Center, University of Oklahoma, Norman, OK, USA 3 NOAA/OAR National Severe Storms validation of WSR-88D radar refractiv- ity retrievals, and discusses some challenges to implementing radar

  9. Shuttle rendezvous radar performance: evaluation and simulation

    Microsoft Academic Search

    J. W. Griffin; A. C. Lindberg; T. B. Ahn; P. L. Harton

    1989-01-01

    The authors describe the performance evaluation and simulation of the Ku-band shuttle rendezvous radar. Computer simulation, using the radar cross section for specific spacecraft, provided an estimate of rendezvous radar range performance for that spacecraft. The radar cross section model included smooth metallic surfaces, rough surfaces, and shadowing effects, as well as phase differences due to different path lengths to

  10. Evaluation of high frequency radar wave measurement

    Microsoft Academic Search

    L. R Wyatt; S. P Thompson; R. R Burton

    1999-01-01

    The spatial coverage, temporal availability and spectral and parameter accuracy of wave measurements using radars operating at the upper end of the high frequency (HF) radio band are discussed. The two radars used are the Ocean Surface Current Radar (OSCR) developed in the UK and the Wellen Radar (WERA) developed in Germany. The measurements show that useful accuracy is obtainable

  11. Soviet oceanographic synthetic aperture radar (SAR) research

    Microsoft Academic Search

    D. N. Held; R. F. Gasparovic; A. W. Mansfield; W. K. Melville; E. L. Mollo-Christensen; H. A. Zebker

    1991-01-01

    Radar non-acoustic anti-submarine warfare (NAASW) became the subject of considerable scientific investigation and controversy in the West subsequent to the discovery by the Seasat satellite in 1978 that manifestations of underwater topography, thought to be hidden from the radar, were visible in synthetic aperture radar (SAR) images of the ocean. In addition, the Seasat radar produced images of ship wakes

  12. The applicability of GMTI MIMO Radar

    Microsoft Academic Search

    Michael Zatman

    2010-01-01

    MIMO Radar has been proposed as a technique for improving the Minimum Detectable Velocity (MDV) performance of airborne radar systems. However, the increased pulse repetition frequency associated with waveform multiplexing techniques used in GMTI MIMO Radar increases the amount of range ambiguous clutter the radar must suppress, reducing the amount of clutter-free Doppler space available to detect targets and often

  13. Aircraft absorbers - Promise and practice

    Microsoft Academic Search

    A. O. Andersson

    1981-01-01

    Attention is given to the application of sound absorbers to aircraft engine ducts. Fan duct application is discussed with reference to the frequency spectrum of fan noise, the wave number spectrum of fan noise, and both local and extended reactions to lining types. The design of duct linings is examined, noting a number of analysis techniques for non-uniform ducts and

  14. Oil and fat absorbing polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr. (inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  15. GEOS-2 C-band system project. C-band radars and their use on the GEOS-2 project

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The material presented covers the general topic of C-band radars and their use throughout the GEOS-2 C-band Radar System Project and has direct application to the general problem of gathering accurate radar tracking data. The material is hardware oriented and all analyses and evaluations described pertain to the gathering of accurate data rather than to the application of the gathered data. The radar oriented investigations formed a basic and necessary part of the overall C-band experiment. The successful completion of these efforts led to the definition of how the radars were to be operated and calibrated. These hardware decisions directly affected the quality of the radar data and therefore played a large part in the successful application of these data to geodetic research.

  16. Experimental Investigation into the Radar Anomalies on the Surface of Venus

    NASA Technical Reports Server (NTRS)

    Kohler, E.; Gavin, P.; Chevrier, V.; Johnson, Natasha M.

    2012-01-01

    Radar mapping of thc surface of Venus shows areas of high reflectivity (low emissivity) in the Venusian highlands at altitudes between 2.5-4.75 kilometers. The origin of the radar anomalies found in the Venusian highlands remains unclear. Most explanations of the potential causes for these radar anomalies come from theoretical work. Previous studies suggest increased surface roughness or materials with higher dielectric constants as well as surface atmospheric interactions. Several possible candidates of high-dielectric materials are tellurium) ferroelectric materials, and lead or bismuth sulfides. While previous studies have been influential in determining possible sources for the Venus anomalies, only a very few hypotheses have been verified via experimentation. This work intends to experimentally constrain the source of the radar anomalies on Venus. This study proposes to investigate four possible materials that could potentially cause the high reflectivities on the surface of Venus and tests their behavior under simulated Venusian conditions.

  17. Large phased-array radars

    SciTech Connect

    Brookner, D.E.

    1988-12-15

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  18. Large phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, Eli, Dr.

    1988-12-01

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  19. Venus Express bistatic radar: High-elevation anomalous reflectivity

    Microsoft Academic Search

    Richard A. Simpson; G. Leonard Tyler; Bernd Häusler; Riccardo Mattei; Martin Pätzold

    2009-01-01

    Magellan (MGN) bistatic radar observations in 1994 confirmed earlier Pioneer Venus reports of unusual Venus surface reflectivity and emissivity at elevations above 6054 km radius. They also revealed that the anomalous values of surface dielectric constant $\\\\varepsilon$ near Cleopatra Patera included a large imaginary component ($\\\\varepsilon$ ? ?i 100) at 13 cm wavelength, consistent with a semiconducting surface material. The

  20. Historical aspects of radar atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Kato, Susumu

    1989-01-01

    A review of the history of radar techniques which have been applied to atmospheric observation is given. The author starts with ionosphere observation with the ionosonde, symbolizing as it does the earliest history of radar observation, and proceeds to later developments in radar observation such as the use of partial reflection, meteor, and incoherent scatter radars. Mesosphere stratosphere troposphere (MST) radars are discussed in terms of lower atmosphere observation.

  1. Imaging radar applications to mapping and charting

    NASA Technical Reports Server (NTRS)

    Leberl, F.

    1976-01-01

    The paper outlines the major actual and potential radar mapping applications, gives an account of the present state of satellite radar imaging, and reviews the radargrammetric work achieved since 1972. Attention is focused on the mapping methods and accuracy regarding single-image radar mapping, stereo radargrammetry, and mapping from blocks of overlapping imagery. It is recommended that more radargrammetric expertise be applied in radar mapping projects so that full advantage may be taken of the metric information potential of imaging radar.

  2. The Clementine bistatic radar experiment.

    PubMed

    Nozette, S; Lichtenberg, C L; Spudis, P; Bonner, R; Ort, W; Malaret, E; Robinson, M; Shoemaker, E M

    1996-11-29

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole. PMID:8929403

  3. The Clementine bistatic radar experiment

    USGS Publications Warehouse

    Nozette, S.; Lichtenberg, C.L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E.M.

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, ??, for selected lunar areas. Observations of the lunar south pole yield a same- sense polarization enhancement around ?? = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  4. Space Radar Images of Earth

    NSDL National Science Digital Library

    Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR), part of NASA's Mission to Planet Earth, is studying how our global environment is changing. From the unique vantage point of space, the radar system observes, monitors and assesses large-scale environmental processes with a focus on climate change. The spaceborne data, complemented by aircraft and ground studies, gives scientists highly detailed information that will help them distinguish natural environmental changes from those that are the result of human activity. The images are divided into nine categories for easier viewing.

  5. The Clementine Bistatic Radar Experiment

    NASA Technical Reports Server (NTRS)

    Nozette, S.; Lichtenberg, C. L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E. M.

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  6. Radar Subsurface Exploration of Icy Moons: Understanding Radar Wave Propagation Through Europa, Ganymede and Callisto

    NASA Astrophysics Data System (ADS)

    Heggy, E.; Scabbia, G.; Pappalardo, R. T.; Bruzzone, L.

    2013-12-01

    Orbital low frequency ice penetrating radars are proposed as a unique tool to probe the first 10 km of the subsurface icy crust of the Jovian satellites, Europa, Ganymede and Callisto. The main objective of our study is to characterize the radar response to the potential presence of aquifers, global ocean and ice tectonic structural elements associated to the moons thermal evolution. We performed a parametric detectability study of the above-mentioned features using the Finite Difference Time Domain (FDTD) method. The forward propagation were performed for a central frequency of 9 MHz, as suggested for future sounding experiments. Simulations were performed for several geoelectrical models that in turn represent different geological hypothesis of Europa, Ganymede and Callisto. We investigated the radar detectability and identification of three main subsurface features: brine aquifers, brittle-ductile interfaces and shallow faults. For each of them we studied the effect of their structural and dielectric properties on their identification considering different geological and geophysical scenarios. In particular we studied the effect of surface clutter and volume scattering on the detectability of the above-mentioned features. The amplitude and losses of the backscattered electromagnetic field of the incident radar pulse were evaluated as a function of the radar range time. Our simulations suggest that aquifer detectability is compromised by its depth, ice impurities content and by the surface and volume scattering. Aquifers are detectable between 7 and 25 dB above the 65 dB galactic noise level at depths ranging respectively from 4 to 2 km. Beyond 4 km of depth and considering the validity of the topographic and dielectric parameters used in our modeling, aquifers could be more challenging for a non ambiguous detection. For the brittle-ductile interface our simulation results suggests that it is identifiable between 2 and 3 km even under highly fractured subsurface conditions. Additionally the depth variation of the brittle ductile interface can be assessed from radar sounding. On contrary, detectability of faults on Ganymede is highly dependent on the dielectric properties of their inner fill materials that is yet to be characterized by our ongoing laboratory characterization of icy moon analog materials.

  7. The performance of sound absorbers in a radial diffuser configuration

    Microsoft Academic Search

    H. L. Scott

    1971-01-01

    A classical wave theory approach is used to determine the radial attenuation in a simulated centrifugal fan or pump diffuser lined with sound absorbing material. For all circumferential modes the attenuation at large radii is virtually the same as that of the lowest mode in a rectangular duct lined on two opposite sides. However, at small radii, the attenuation rate

  8. Polymers used to absorb fats and oils: A concept

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.

    1974-01-01

    One approach to problem of excessive oils and fats is to develop method by which oil is absorbed into solid mixture for elimination as solid waste. Materials proposed for these purposes are cross-linked (network) polymers that have high affinity for aliphatic substances, i. e., petroleum, animal, and vegetable oils.

  9. Design of absorber assemblies with intentional pellet-cladding mechanical interaction. [LMFBR

    SciTech Connect

    Hollenberg, G.W.; Birney, K.R.; Pitner, A.L.; Basmajian, J.A.

    1980-04-01

    A number of improvements in absorber assembly performance characteristics can be achieved through implementation of absorber cladding mechanical interaction (ACMI). Benefits include lower operating temperatures, less potential for material relocation, longer lifetime, and increased reactivity worth. Analyses indicate that substantial cladding strains may be attainable without significant risk of breach. However, actual in-reactor testing of ACMI in absorber elements will be required before design criteria can be revised to accept ACMI.

  10. Venus - Concentrations of radar-reflective minerals by wind

    SciTech Connect

    Greeley, R.; Marshall, J.R.; Dobrovolskis, A.R.; Clemens, D.; Pollack, J.B. (Arizona State Univ., Tempe (USA) NASA, Moffett Field, CA (USA))

    1991-03-01

    The effectiveness of wind in concentrating minerals with high radar reflectiveness on the surface of Venus is investigated experimentally in the Venus Wind Tunnel (Greeley et al., 1984) under CO{sub 2} densities typical of Venusian conditions. Density sorting of sand particles during the formation of microdunes is demonstrated, and calculations show that wind-blown deposits of dense conductive material such as ilmenite need to be only a few cm thick to account for the local enhancements of radar reflectivity observed by Pioneer Venus at wavelength 17 cm. 28 refs.

  11. Probing the Martian Subsurface with Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Campbell, B. A.; Maxwell, T. A.; Freeman, A.

    2005-01-01

    Many regions of the martian surface are covered by fine-grained materials emplaced by volcanic, fluvial, or aeolian processes. These mantling deposits likely hide ancient channel systems (particularly at smaller scale lengths) and volcanic, impact, glacial, or shoreline features. Synthetic aperture radar (SAR) offers the capability to probe meters below the surface, with imaging resolution in the 10 s of m range, to reveal the buried terrain and enhance our understanding of Mars geologic and climate history. This presentation focuses on the practical applications of a Mars orbital SAR, methods for polarimetric and interferometric radar studies, and examples of such techniques for Mars-analog sites on the Moon and Earth.

  12. Airborne bistatic radar applications

    NASA Astrophysics Data System (ADS)

    Foster, James A.

    1987-09-01

    Applications of bistatic radar when one or both of the units are airborne are discussed. Scenarios that merit deeper consideration are covert strike and head-on SAR using a stand-off illuminator, either airborne or space-based; area air defense with passive ground-based receivers and stand-off illuminators; an airborne picket line to detect stealth aircraft and missiles; AWACS aircraft providing mutual support in ECM environments; and passive surveillance of hostile air space using illuminators of opportunity and an airborne receiver. Scenarios considered impractical are bistatic air-to-air missile guidance using an aircraft other than the launch aircraft as illuminator; passive interdiction using illuminators of opportunity; and scenarios involving a ground based illuminator and an aircraft as the receiver.

  13. Radar backscatter modelling

    NASA Astrophysics Data System (ADS)

    Schaber, G. G.; Kozak, R. C.; Gurule, R. L.

    1984-04-01

    The terrain analysis software package was restructured and documentation was added. A program was written to test Johnson Space Center's four band scatterometer data for spurious signals data. A catalog of terrain roughness statistics and calibrated four frequency multipolarization scatterometer data is being published to support the maintenance of Death Valley as a radar backscatter calibration test site for all future airborne and spacecraft missions. Test pits were dug through sand covered terrains in the Eastern Sahara to define the depth and character of subsurface interfaces responsible for either backscatter or specular response in SIR-A imagery. Blocky sandstone bedrock surfaces at about 1 m depth were responsible for the brightest SIR-A returns. Irregular very dense CaCO3 cemented sand interfaces were responsible for intermediate grey tones. Ancient river valleys had the weakest response. Reexamination of SEASAT l-band imagery of U.S. deserts continues.

  14. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

  15. Is the Martian Water Table Hidden from Radar View?

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Plaut, J. J.; Cummer, S. A.; Gurnett, D. A.; Picardi, G.; Watters, T. R.; Safaeinili, A.

    2009-01-01

    Mars may possess a global sub-surface groundwater table as an integral part of its current hydrological system, However, the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the 'Mars Express (MEx) spacecraft has yet to make a definitive detection of such a body of liquid water. In this work, we quantify. the conditions that would allow a detection of a deep aquifer and demonstrate that the lack of radar detection doses not uniquely role out the presence of such a body. Specifically, if the overlying crustal material has a conductivity above approximately 10(exp -5) S/m (equivalent to a loss tangent of 0.008), a radar echo frown an aquifer could be sufficiently attenuated by the intetvening medium to prevent its detection by MARSIS. As such, the lack of direct detection by MARSIS -- a "null result" does not rule out the possibility of the water table's existence.

  16. Advanced Borehole Radar for Hydrogeology

    NASA Astrophysics Data System (ADS)

    Sato, M.

    2014-12-01

    Ground Penetrating Radar is a useful tool for monitoring the hydrogeological environment. We have developed GPR systems which can be applied to these purposes, and we will demonstrate examples borehole radar measurements. In order to have longer radar detection range, frequency lower than100MHz has been normally adopted in borehole radar. Typical subsurface fractures of our interests have a few mm aperture and radar resolution is much poorer than a few cm in this frequency range. We are proposing and demonstrating to use radar polarimetry to solve this problem. We have demonstrated that a full-polarimetry borehole radar can be used for characterization of subsurface fractures. Together with signal processing for antenna characteristic compensation to equalize the signal by a dipole antenna and slot antennas, we could demonstrate that polarimetric borehole radar can estimate the surface roughness of subsurface fractures, We believe the surface roughness is closely related to water permeability through the fractures. We then developed a directional borehole radar, which uses optical field sensor. A dipole antenna in a borehole has omni-directional radiation pattern, and we cannot get azimuthal information about the scatterers. We use multiple dipole antennas set around the borehole axis, and from the phase differences, we can estimate the 3-diemnational orientation of subsurface structures. We are using optical electric field sensor for receiver of borehole radar. This is a passive sensor and connected only with optical fibers and does not require any electric power supply to operate the receiver. It has two major advantages; the first one is that the receiver can be electrically isolated from other parts, and wave coupling to a logging cable is avoided. Then, secondary, it can operate for a long time, because it does not require battery installed inside the system. It makes it possible to set sensors in fixed positions to monitor the change of environmental conditions for a long period. We demonstrated this idea using cross- hole borehole radar measurement. We think this method is useful for detecting any changes in hydrogeological situations, which will be useful for subsurface storage such as LNG and nuclear waste.

  17. Absorbable biologically based internal fixation.

    PubMed

    Ibrahim, Ahmed M S; Koolen, Pieter G L; Kim, Kuylhee; Perrone, Gabe S; Kaplan, David L; Lin, Samuel J

    2015-01-01

    Absorbable devices for use in internal fixation have advanced over the years to become reliable and cost-effective alternatives to metallic hardware. In the past, biodegradable fixation involved a laborious implantation process, and induced osteolysis and inflammatory reactions. Modern iterations exhibit increased strength, smoother resorption, and lower rates of reactivity. A newer generation manufactured from silk has emerged that may address existing limitations and provide a greater range of fixation applications. PMID:25440418

  18. Radar imaging of Saturn's rings

    Microsoft Academic Search

    Philip D. Nicholson; Richard G. French; Donald B. Campbell; Jean-Luc Margot; Michael C. Nolan; Gregory J. Black; Heikki J. Salo

    2005-01-01

    We present delay–Doppler images of Saturn's rings based on radar observations made at Arecibo Observatory between 1999 and 2003, at a wavelength of 12.6 cm and at ring opening angles of 20.1°?|B|?26.7°. The average radar cross-section of the A ring is ?77% relative to that of the B ring, while a stringent upper limit of 3% is placed on the

  19. Rendezvous radar for orbital vehicles

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Casey, Larry D.

    1992-03-01

    In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of hi-rel electronics hardware for space is discussed.

  20. The NASA Polarimetric Radar (NPOL)

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; Wolff, David B.

    2013-01-01

    Characteristics of the NASA NPOL S-band dual-polarimetric radar are presented including its operating characteristics, field configuration, scanning capabilities and calibration approaches. Examples of precipitation science data collections conducted using various scan types, and associated products, are presented for different convective system types and previous field campaign deployments. Finally, the NASA NPOL radar location is depicted in its home base configuration within the greater Wallops Flight Facility precipitation research array supporting NASA Global Precipitation Measurement Mission ground validation.

  1. Absorbing properties of ?-manganese dioxide/carbon black double-layer composites

    NASA Astrophysics Data System (ADS)

    Duan, Yuping; Yang, Yang; He, Ma; Liu, Shunhua; Cui, Xiaodong; Chen, Huifeng

    2008-06-01

    In order to improve the absorbing properties of the electromagnetic wave absorbing plate, double-layer wave absorbing materials, which are composed of a matching layer and an absorbing layer, were devised. The matching layer is a surface layer of the wave absorbing sample, from which most of the incident waves easily enter the sample, and the absorbing layer is a second layer under the matching layer, which plays an important role in incident wave attenuation. The total thickness of the double-layer composites is the sum of the thicknesses of the matching layer and the absorbing layer. In this paper, ?-manganese dioxide and carbon black (CB) were used as absorbents in the matching layer and the absorbing layer respectively. Meanwhile, the structure of the ?-manganese dioxide and the CB particles were analysed by x-ray diffraction and transmission electron microscopy, and the dielectric property and absorbing mechanics were also studied. The results showed that, in the case of the mass fraction of CB in the absorbing layer being 30% and the thickness of the absorbing layer being 3 mm, the effectual absorption band (below -10 dB) of the double-layer wave absorbing materials reaches 8.6 GHz and 7.6 GHz in the testing frequency range between 8 GHz and 18 GHz, respectively, when the mass fraction of ?-MnO2 in the matching layer was 10% and the thicknesses of the matching layer were 2 mm and 1 mm, respectively, and the effectual absorption band (below -10 dB) reaches 8.7 GHz in 8 18 GHz when the mass fraction of ?-MnO2 in the matching layer was 20% and the thickness of the matching layer was 2 mm.

  2. Study of Coupling on Parallel Microstrip Lines Due to Magnetic-Loaded Absorber Sheet

    Microsoft Academic Search

    Jure Koselj; Andrej Znidarsic; Vladimir B. Bregar

    2008-01-01

    Coupling effect of magnetic-loaded absorbing materials on parallel microstrip lines was investigated numerically and experimentally. A microstrip circuits with two 50 Omega parallel lines with different distances between the lines were used to experimentally evaluate coupling effect and the same configuration was modeled and evaluated with finite-element method numerical program. Results showed that absorber sheets, placed over microstrip lines significantly

  3. Iodide-capped PbS quantum dots: full optical characterization of a versatile absorber.

    PubMed

    Stadler, Philipp; Mohamed, Shaimaa A; Gasiorowski, Jacek; Sytnyk, Mykhailo; Yakunin, Sergii; Scharber, Markus C; Enengl, Christina; Enengl, Sandra; Egbe, Daniel A M; El-Mansy, Mabrouk K; Obayya, Salah S A; Sariciftci, N Serdar; Hingerl, Kurt; Heiss, Wolfgang

    2015-03-01

    Lead sulfide quantum dots represent an emerging photovoltaic absorber material. While their associated optical qualities are true for the colloidal solution phase, they change upon processing into thin-films. A detailed view to the optical key-parameters during solid-film development is presented and the limits and outlooks for this versatile and promising absorber are discussed. PMID:25612163

  4. Space-based radar antenna thermal control

    NASA Astrophysics Data System (ADS)

    Vrable, Daniel L.; Vrable, Michael D.

    2001-02-01

    Improved thermal management for large planar phased array antennas proposed for future spaced-based radar applications in Low Earth Orbit (LEO) is a critical issue. Effective and lightweight thermal management concepts are required to enhance thermal control and provide near isothermal operation during transit between daylight and eclipse periods and radar electronic power-on and off operation. Due to the planar array's large area the antenna has sufficient area to radiate the deposited power during both eclipse and daylight periods. The critical issue is keeping the antenna warm during the eclipse period, thereby maintaining the structure and sensitive electronic components near an isothermal condition. The thermal concept discussed provides a totally passive, lightweight and highly effective thermal control approach. The concept utilizes a phase change material (PCM), which exploits the large latent heat capacity for effective energy storage. In addition, the concept utilizes a new lightweight and high thermal conductivity carbon foam material to integrally contain or encapsulate the PCM. The carbon foam thermal conductivity and cell geometric characteristics result in effective thermal transfer during both thermal energy storage and extraction. The overall design concept provides a weight efficient and highly effective thermal control approach that requires no additional parasitic power. High payoff includes improved temperature control for near isothermal operation of the antenna array during the entire orbit. .

  5. Numerical modeling of ground-penetrating radar in 2-D using MATLAB

    NASA Astrophysics Data System (ADS)

    Irving, James; Knight, Rosemary

    2006-11-01

    We present MATLAB codes for finite-difference time-domain (FDTD) modeling of ground-penetrating radar (GPR) in two dimensions. Surface-based reflection GPR is modeled using a transverse magnetic (TM-) mode formulation. Crosshole and vertical radar profiling (VRP) geometries are modeled using a transverse electric (TE-) mode formulation. Matrix notation is used in the codes wherever possible to optimize them for speed in the MATLAB environment. To absorb waves at the edges of the modeling grid, we implement perfectly matched layer (PML) absorbing boundaries. Although our codes are two-dimensional and do not incorporate features such as dispersion in electrical properties, they capture many of the important elements of GPR surveying and run at a fraction of the computational cost of more elaborate algorithms. In addition, the codes are well commented, relatively easy to understand, and can be easily modified for the user's specific purpose.

  6. Radar reflectivity calibration using differential propagation phase measurement

    E-print Network

    Zhang, Guifu

    Radar reflectivity calibration using differential propagation phase measurement J. Vivekanandan,1 reflectivity using polarization radar measurements in rain is described. Accurate calibration of radar reflectivity is essential for obtaining reliable rain rate estimation. In the case of polarization radar, rain

  7. Neutron absorbed dose determination by calculations of recoil energy.

    PubMed

    Wrobel, F; Benabdesselam, M; Iacconi, P; Lapraz, D

    2004-01-01

    The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy. PMID:15353750

  8. Fabrication and microwave absorbing properties of NixPy nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Haoran; Wan, Lei; Chen, Yaqiong; Hu, Wenbin; Liu, Lei; Zhong, Cheng; Deng, Yida

    2015-06-01

    Materials possessing microwave absorbing properties have been a researching hotspot for their important applications amid a high frequency electromagnetic waves environment. This paper focuses on the preparation of a series of NixPy(x:y = 2.65–2.73) nanotubes (NTs) and their corresponding microwave absorbing properties. After being heat-treated, different NixPy phases would appear, without damaging their initial hollow morphologies. These processes were accompanied with the alteration of related physical properties. Low enough minimum reflection loss (RL) has been achieved in all of these samples, with??48.63?dB as the lowest one being obtained at the non-heat-treated sample. Besides, a large proportion of the microwave frequency band could be covered on the 450?°C heat-treated sample (over a 4.5?GHz bandwidth). These are indicative of the superior microwave absorbing nature of NixPy NTs.

  9. VLA/Goldstone (California) planetary radar results

    NASA Technical Reports Server (NTRS)

    Grossman, A. W.; Muhleman, D. O.; Slade, M. A.; Butler, B. J.

    1991-01-01

    Recent results from an entirely new technique of planetary radar astronomy are presented. The Very Large Array (VLA)/Goldstone planetary radar combines the transmitter of the Goldstone antenna and the receivers of the VLA interferometer to create a synthesis imaging radar instrument with unprecedented capabilities. The technique yields improved sensitivity and produces a direct sky map of radar flux density while avoiding the ambiguities associated with conventional range Doppler mapping. The method is illustrated by application to radar mapping of Mars and radar detection of Titan.

  10. Australian Weather Watch Radar Home Page

    NSDL National Science Digital Library

    The Commonwealth Bureau of Meteorology's Weather Watch Radar website provides up-to-date radar images of the locations of rain in Australia in relation to local features such as coast lines. The newly developed Loops provide four consecutive radar images so that users can view how the weather has been changing in the last forty to fifty minutes. The website provides radar images of past cyclone events as well as updates on severe weather throughout Australia. Those interested in radar systems can discover how the weather radars work and how to interpret the maps. [RME

  11. Results of the design and testing of a porous ceramic absorber for a volumetric air receiver

    SciTech Connect

    Chavez, J.M. (Sandia National Labs., Albuquerque, NM (USA)); Chaza, C. (Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Almeria (Spain))

    1990-05-10

    A new absorber for a volumetric receiver was designed, built and tested on an existing volumetric receiver test bed (200 kW{sub t}) at the Plataforma Solar de Almeria test facility in Spain. Volumetric air receivers are currently being investigated for use in solar central receiver power plants because of their inherent simplicity. The volume air receiver is a unique type of solar central receiver that uses a porous absorber (heat exchanger), on which the solar energy is concentrated and absorbed within its volume. Air flows through the absorber, convectively transferring energy from the absorber to the air. Volumetric receivers have applications in electricity production, industrial process heat, and chemical processing. We designed this new volumetric receiver absorber to use a porous ceramic. This material was selected because of its structural strength, high temperature capability, and the potential for using smaller pieces to build up an absorber. The ceramic absorber was tested at the Plataforma Solar de Almeria with a solar flux of up to 1200 kW/m{sup 2}, and it produced outlet air temperatures of 730{degree}C. The porous ceramic material has exhibited reasonable thermal efficiencies and excellent structural integrity in the high-flux, high-temperature environment. In this paper we summarize previous tests on the volumetric air receiver and present the current absorber design and test results. 12 refs., 6 figs.

  12. Semiconductor nanowire optical antenna solar absorbers.

    PubMed

    Cao, Linyou; Fan, Pengyu; Vasudev, Alok P; White, Justin S; Yu, Zongfu; Cai, Wenshan; Schuller, Jon A; Fan, Shanhui; Brongersma, Mark L

    2010-02-10

    Photovoltaic (PV) cells can serve as a virtually unlimited clean source of energy by converting sunlight into electrical power. Their importance is reflected in the tireless efforts that have been devoted to improving the electrical and structural properties of PV materials. More recently, photon management (PM) has emerged as a powerful additional means to boost energy conversion efficiencies. Here, we demonstrate an entirely new PM strategy that capitalizes on strong broad band optical antenna effects in one-dimensional semiconductor nanostructures to dramatically enhance absorption of sunlight. We show that the absorption of sunlight in Si nanowires (Si NWs) can be significantly enhanced over the bulk. The NW's optical properties also naturally give rise to an improved angular response. We propose that by patterning the silicon layer in a thin film PV cell into an array of NWs, one can boost the absorption for solar radiation by 25% while utilizing less than half of the semiconductor material (250% increase in the light absorption per unit volume of material). These results significantly advance our understanding of the way sunlight is absorbed by one-dimensional semiconductor nanostructures and provide a clear, intuitive guidance for the design of efficient NW solar cells. The presented approach is universal to any semiconductor and a wide range of nanostructures; as such, it provides a new PV platform technology. PMID:20078065

  13. Mulitlayered Nanostructured Broad Band Absorber

    NASA Astrophysics Data System (ADS)

    Corrigan, Timothy; Ide, Benjamin

    2013-03-01

    Wasted energy in the form of heat is perhaps the largest source of lost energy making many power systems inefficient. Systems designed to convert heat into useful energy need a method of collecting the heat. We previously described a multilayer design with successive thin metallic and dielectric (non-metal and transparent) layers, where each successive metallic layer absorbs a small fraction of the radiation. However, the regular thickness of the dielectric layer causes reflection peaks, or regions where no absorption occurs. In this work we describe a similar design where we eliminated the undesirable reflection peaks using varying thicknesses of the dielectric layer.

  14. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...false Absorbable implant (scleral buckling method). 886.3300 Section...3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a device intended...

  15. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...false Absorbable implant (scleral buckling method). 886.3300 Section...3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a device intended...

  16. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...false Absorbable implant (scleral buckling method). 886.3300 Section...3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a device intended...

  17. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...false Absorbable implant (scleral buckling method). 886.3300 Section...3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a device intended...

  18. Microwave absorbance properties of zirconium–manganese substituted cobalt nanoferrite as electromagnetic (EM) wave absorbers

    SciTech Connect

    Khan, Kishwar, E-mail: kknano@hotmail.com; Rehman, Sarish

    2014-02-01

    Highlights: • Good candidates for EM materials with low reflectivity. • Good candidates for broad bandwidth at microwave frequency. • Microwave absorbing bandwidth was modulated simply by manipulating the Zr–Mn. • Higher the Zr–Mn content, the higher absorption rates for the electromagnetic radiation. • The predicted reflection loss shows that this can be used for thin ferrite absorber. - Abstract: Nanocrystalline Zr–Mn (x) substituted Co ferrite having chemical formula CoFe{sub 2?2x}Zr{sub x}Mn{sub x}O{sub 4} (x = 0.1–0.4) was prepared by co-precipitation technique. Combining properties such as structural, electrical, magnetic and reflection loss characteristics. Crystal structure and surface morphology of the calcined samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). By using two point probe homemade resistivity apparatus to find resistivity of the sample. Electromagnetic (EM) properties are measured through RF impedance/materials analyzer over 1 MHz–3 GHz. The room-temperature dielectric measurements show dispersion behavior with increasing frequency from 100 Hz to 3 MHz. Magnetic properties confirmed relatively strong dependence of saturation magnetization on Zr–Mn composition. Curie temperature is also found to decrease linearly with addition of Zr–Mn. Furthermore, comprehensive analysis of microwave reflection loss (RL) is carried out as a function of substitution, frequency, and thickness. Composition accompanying maximum microwave absorption is suggested.

  19. SUBMITTED TO IEE PROCEEDINGS RADAR, SONAR & NAVIGATION 1 Region-Enhanced Passive Radar Imaging

    E-print Network

    Willsky, Alan S.

    SUBMITTED TO IEE PROCEEDINGS RADAR, SONAR & NAVIGATION 1 Region-Enhanced Passive Radar Imaging M;SUBMITTED TO IEE PROCEEDINGS RADAR, SONAR & NAVIGATION 2 Abstract We adapt and apply a recently-developed region-enhanced synthetic aperture radar (SAR) image reconstruction technique to the problem of passive

  20. Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility

    E-print Network

    Paris-Sud XI, Université de

    Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility D. M is a new polar cap HF radar facility which is to be deployed on Svalbard. The principal capabilities of SPEAR will include the generation of arti®cial plasma irregularities, operation as an `all-sky' HF radar

  1. Multifrequency and multipolarization radar scatterometry of sand dunes and comparison with spaceborne and airborne radar images

    Microsoft Academic Search

    Ronald Blom; Charles Elachi

    1987-01-01

    Understanding the unusual radar scattering characteristics of sand dunes is necessary in the analysis of radar images of aeolian landscapes of the earth and of other planets. In this paper we report on airborne radar scatterometer data of sand dunes, acquired at multiple frequencies and polarizations. Radar backscatter from sand dunes is very sensitive to the imaging geometry. At small

  2. Imaging radar techniques for remote sensing applications.

    NASA Technical Reports Server (NTRS)

    Zelenka, J. S.

    1972-01-01

    The basic concepts of fine-resolution, imaging radar systems are reviewed. Both side-looking and hologram (downward-looking) radars are described and compared. Several examples of microwave imagery obtained with these two types of systems are shown.

  3. Obstacle penetrating dynamic radar imaging system

    DOEpatents

    Romero, Carlos E. (Livermore, CA); Zumstein, James E. (Livermore, CA); Chang, John T. (Danville, CA); Leach, Jr.. Richard R. (Castro Valley, CA)

    2006-12-12

    An obstacle penetrating dynamic radar imaging system for the detection, tracking, and imaging of an individual, animal, or object comprising a multiplicity of low power ultra wideband radar units that produce a set of return radar signals from the individual, animal, or object, and a processing system for said set of return radar signals for detection, tracking, and imaging of the individual, animal, or object. The system provides a radar video system for detecting and tracking an individual, animal, or object by producing a set of return radar signals from the individual, animal, or object with a multiplicity of low power ultra wideband radar units, and processing said set of return radar signals for detecting and tracking of the individual, animal, or object.

  4. Exploring Materials: Hydrogel

    NSDL National Science Digital Library

    Nanoscale Informal Science Education Network

    2011-01-01

    In this activity, learners discover how a super-absorbing material can be used to move a straw. Learners discover that hydrogels can absorb a lot of water, like the one used in this activity, which can absorb 1,000 times its weight in water! Use this activity to discuss how hydrogels can be used at the nanoscale to manipulate tiny structures. Activities with Jell-O® are a great complement to this activity, since Jell-O® is also a hydrogel!

  5. Radar Mosaic of Africa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is an image of equatorial Africa, centered on the equator at longitude 15degrees east. This image is a mosaic of almost 4,000 separate images obtained in 1996 by the L-band imaging radar onboard the Japanese Earth Resources Satellite. Using radar to penetrate the persistent clouds prevalent in tropical forests, the Japanese Earth Resources Satellite was able for the first time to image at high resolution this continental scale region during single flooding seasons. The area shown covers about 7.4 million square kilometers (2.8 million square miles) of land surface, spans more than 5,000 kilometers(3,100 miles) east and west and some 2,000 kilometers (1,240 miles) north and south. North is up in this image. At the full resolution of the mosaic (100 meters or 330 feet), this image is more than 500 megabytes in size, and was processed from imagery totaling more than 60 gigabytes.

    Central Africa was imaged twice in 1996, once between January and March, which is the major low-flood season in the Congo Basin, and once between October and November, which is the major high-flood season in the Congo Basin. The red color corresponds to the data from the low-flood season, the green to the high-flood season, and the blue to the 'texture' of the low-flood data. The forests appear green as a result, the flooded and palm forests, as well as urban areas, appear yellow, the ocean and lakes appear black, and savanna areas appear blue, black or green, depending on the savanna type, surface topography and other factors. The areas of the image that are black and white were mapped only between January and March 1996. In these areas, the black areas are savanna or open water, the gray are forests, and the white areas are flooded forests or urban areas. The Congo River dominates the middle of the image, where the nearby forests that are periodically flooded by the Congo and its tributaries stand out as yellow. The Nile River flows north from Lake Victoria in the middle right of the color portion of the mosaic.

    This image is one of the products resulting from the Global Rain Forest Mapping project, a joint project between the National Space Development Agency of Japan, the Space Applications Institute of the Joint Research Centre of the European Commission, NASA's Jet Propulsion Laboratory and an international team of scientists. The goal of the Global Rain Forest Mapping mission is to map with the Japanese Earth Resources Satellite the world's tropical rain forests. The Japanese satellite was launched in 1992 by the National Space Development Agency of Japan and the Japanese Ministry of International Trade and Industry, with support from the Remote Sensing Technology Center of Japan.

  6. Radar reflection off extensive air showers

    E-print Network

    Stasielak, J; Bertaina, M; Blümer, J; Chiavassa, A; Engel, R; Haungs, A; Huege, T; Kampert, K -H; Klages, H; Kleifges, M; Krömer, O; Ludwig, M; Mathys, S; Neunteufel, P; Pekala, J; Rautenberg, J; Riegel, M; Roth, M; Salamida, F; Schieler, H; Šmída, R; Unger, M; Weber, M; Werner, F; Wilczy?ski, H; Wochele, J

    2012-01-01

    We investigate the possibility of detecting extensive air showers by the radar technique. Considering a bistatic radar system and different shower geometries, we simulate reflection of radio waves off the static plasma produced by the shower in the air. Using the Thomson cross-section for radio wave reflection, we obtain the time evolution of the signal received by the antennas. The frequency upshift of the radar echo and the power received are studied to verify the feasibility of the radar detection technique.

  7. Bird-aircraft strike avoidance radar

    Microsoft Academic Search

    Ning Huansheng; Chen Weishi; Mao Xia; Li Jing

    2010-01-01

    Avian radar system has been developed for bird-aircraft strike hazard avoidance. Two representative systems, which are countrywide and airport-based avian radar systems, are surveyed to summarize the state-of-the-art in this research field. Avian radar experimental system built by Beihang University is introduced in detail, including system architecture, performance analysis, and processing algorithm for bird target detection and tracking. This radar

  8. Radar Images of the Earth: Volcanoes

    NSDL National Science Digital Library

    This site features links to thirty-five NASA radar images of the world's volcanoes, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

  9. Bistatic synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Yates, Gillian

    Synthetic aperture radar (SAR) allows all-weather, day and night, surface surveillance and has the ability to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and the receiver are on separate platforms, is seen as a potential means of countering the vulnerability of conventional monostatic SAR to electronic countermeasures, particularly directional jamming, and avoiding physical attack of the imaging platform. As the receiving platform can be totally passive, it does not advertise its position by RF emissions. The transmitter is not susceptible to jamming and can, for example, operate at long stand-off ranges to reduce its vulnerability to physical attack. This thesis examines some of the complications involved in producing high-resolution bistatic SAR imagery. The effect of bistatic operation on resolution is examined from a theoretical viewpoint and analytical expressions for resolution are developed. These expressions are verified by simulation work using a simple 'point by point' processor. This work is extended to look at using modern practical processing engines for bistatic geometries. Adaptations of the polar format algorithm and range migration algorithm are considered. The principal achievement of this work is a fully airborne demonstration of bistatic SAR. The route taken in reaching this is given, along with some results. The bistatic SAR imagery is analysed and compared to the monostatic imagery collected at the same time. Demonstrating high-resolution bistatic SAR imagery using two airborne platforms represents what I believe to be a European first and is likely to be the first time that this has been achieved outside the US (the UK has very little insight into US work on this topic). Bistatic target characteristics are examined through the use of simulations. This also compares bistatic imagery with monostatic and gives further insight into the utility of bistatic SAR.

  10. Scanning ARM Cloud Radar Handbook

    SciTech Connect

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  11. The PROUST radar: First results

    NASA Technical Reports Server (NTRS)

    Bertin, F.; Cremieu, A.; Glass, M.; Massebeuf, M.; Petitdidier, M.

    1986-01-01

    Two campaigns took place in 1984 with the PROUST Radar operating in a bistatic mode, the transmitting antenna pointing at the vertical and the receiving one, 1 deg. off the vertical axis. The antenna beam intersection covers an altitude range between 3 and 9 km. The first of these campaigns are analyzed. The results analyzed show the capability of the PROUST Radar to measure the turbulent parameters and study the turbulence-wave interaction. In its present configuration (bistatic mode and 600 m vertical resolution), it has been necessary to make some assumptions that are known not to be truly fulfilled: homogeneous turbulence and constant vertical wind intensity over a 600-m thickness. It is clear that a more detailed study of the interaction between wave and turbulence will be possible with the next version of PROUST Radar (30-m altitude resolution and monostatic mode) that will soon be achieved.

  12. Spaceborne radar studies of Venus

    SciTech Connect

    Nozette, S.

    1980-01-01

    Data obtained from the Pioneer Venus radar mapper experiment are discussed. The mission was primarily developed to study the atmosphere of Venus. A highly eccentric orbit (eccentricity of 0.84, period of 24 h) was selected. The instrumentation has two operating modes: altimetry and imaging. Three parameters were measured for every radar spot size: altitude, surface roughness and radar reflectivity at a normal incidence. The measurements have been extended to a topographic map. The results suggest that the Beta region consists of two large shields and that the equatorial region is dominated by Aphrodite Terra. It also appears that the surface of Venus is very smooth and that it lacks great basins and the global plate tectonics present on earth.

  13. SMAP RADAR Processing and Calibration

    NASA Astrophysics Data System (ADS)

    West, R. D.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M. J.

    2013-12-01

    The Soil Moisture Active Passive (SMAP) mission uses L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This presentation will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation. To obtain the desired high spatial resolution the level 1 radar ground processor employs synthetic aperture radar (SAR) imaging techniques. Part of the challenge of the SMAP data processing comes from doing SAR imaging on a conically scanned system with rapidly varying squint angles. The radar echo energy will be divided into range/Doppler bins using time domain processing algorithms that can easily follow the varying squint angle. For SMAP, projected range resolution is about 250 meters, while azimuth resolution varies from 400 meters to 1.2 km. Radiometric calibration of the SMAP radar means measuring, characterizing, and where necessary correcting the gain and noise contributions from every part of the system from the antenna radiation pattern all the way to the ground processing algorithms. The SMAP antenna pattern will be computed using an accurate antenna model, and then validated post-launch using homogeneous external targets such as the Amazon rain forest to look for uncorrected gain variation. Noise subtraction is applied after image processing using measurements from a noise only channel. Variations of the internal electronics are tracked by a loopback measurement which will capture most of the time and temperature variations of the transmit power and receiver gain. Long-term variations of system performance due to component aging will be tracked and corrected using stable external reference targets. Candidate targets include the Amazon rain forest and a model-corrected global ocean measurement. Radio frequency interference (RFI) signals are expected in the L-band frequency window used by the SMAP radar because many other users also operate in this band. Based on results of prior studies at JPL, SMAP L1 radar processing will use a "Slow-time thresholding" or STT algorithm to handle RFI contamination. The STT technique looks at the slow-time series associated with a given range sample, sets an appropriate threshold, and identifies any samples that rise above this threshold as RFI events. The RFI events are removed and the data are azimuth compressed without those samples. Faraday rotation affects L-band signals by rotating the polarization vector during propagation through the ionosphere. This mixes HH, VV, HV, and VH results with each other introducing another source of error. The SMAP radar is not fully polarimetric so the radar data do not provide a correction by themselves. Instead a correction must be derived from other sources. L1 radar processing will use estimates of Faraday rotation derived from externally supplied GPS-based measurements of the ionosphere total electron content (TEC). This work is supported by the SMAP project at the Jet Propulsion Laboratory, California Institute of Technology.

  14. Comprehensive soil surface characterisation by RADAR

    NASA Astrophysics Data System (ADS)

    Seeger, Manuel; Gronz, Oliver; Beiske, Joshua

    2015-04-01

    The characteristics of the soil's surface have been revealed to be extremely relevant for soil surface processes. Texture, aggregates and roughness are interdependent across scales and have a strong influence on infiltration, runoff generation, water flow velocity as well as on particle detachment and transport. They also have shown to be relevant for splash detachment and initialisation of concentrated flow. But these soil surface characteristics are also highly variable during erosive events, and thus, their impact on the processes mentioned above may change. Therefore it is necessary to develop methods for a comprehensive and quantitative characterisation of the soils' surface across scales. Here, we present a first approach using a frequency modulated polarimetric radar to characterise different surfaces (from flat to rough in a scale of cm to dm size of the roughness elements) and of different materials (steel plates as strong reflector, sand [0.5-1 mm], fine [2-4 mm] and coarse [15-30 mm] rock fragments. The radar is a prototype built by IMST GmbH (Kamp-Lintfort, Germany), emitting on the 24 GHz band, allowing for a frequency modulation between 500 and 2500 MHz with variable ramp times. The emission is on a circular clockwise polarisation, whilst it is able to receive both, clockwise and counter-clockwise polarisations. We tested also the dependency of the reflected signals on imaging position and angle, as well as on the different emission parameters, such as amplitude modulation and ramp time. The results show that the angle of acquisition influences clearly the received signal intensity (in both polarisation directions). This implies the need to develop topographical corrections for further applications. In addition we could observe a significant influence of the device position on the results, which implies, on one hand, a high sensitivity relating to the soil's surface, but on the other hand it leads to a high level of uncertainty. The reflection characteristics of the different targets, as expressed by the median and the standard deviation of the intensity of both received polarisations, allow the differentiation of different roughness levels. In addition, the radar signals allow also the differentiation of the different mineral substrates. Thus, the radar system shows a capability to characterise soil surface characteristics at different scale levels between mm and dm size of the elements. But until now, the signal composition and their evaluation did not make it possible to develop a clear index for the different surface properties. This makes the development of further evaluation routines mandatory, but also the development of comprehensive indexes for characterising soil surface roughness.

  15. WAVE-DRIVEN SURFACE FROM HF RADAR

    E-print Network

    Miami, University of

    FEATURE INTERNAL CURRENTS WAVE-DRIVEN SURFACE FROM HF RADAR By Lynn K. Shay Observations from-fre- quency (HF) radar have revealed that not only are the low-frequency and tidal currents resolved of the horizontal flow structure from HF radar pro- vides the spatial context for moored and ship- based

  16. Spaceborne imaging radar-C instrument

    Microsoft Academic Search

    BRYAN L. HUNEYCUTT

    1989-01-01

    The Shuttle Imaging Radar (SIR)-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low Earth orbit. It is a multiparameter imaging radar that will be flown during two different seasons. The instrument has been designed to operate in innovative modes such as the squint mode, the extended aperture mode, and the scansar mode,

  17. High-power transmitters for radar applications

    Microsoft Academic Search

    Meppalli K. Shandas

    2009-01-01

    High-power transmitters are one of the critical elements in a radar system. The radar waveform needs to be amplified without distortion to the desired output power level by the high-power transmitter. In addition to affecting the overall performance of the radar system, the design of the transmitter affects many other factors, such as size, weight, power consumption, operating cost, reliability

  18. Radar geomorphology of coastal and wetland environments

    NASA Technical Reports Server (NTRS)

    Lewis, A. J.; Macdonald, H. C.

    1973-01-01

    Details regarding the collection of radar imagery over the past ten years are considered together with the geomorphic, geologic, and hydrologic data which have been extracted from radar imagery. Recent investigations were conducted of the Louisiana swamp marsh and the Oregon coast. It was found that radar imagery is a useful tool to the scientist involved in wetland research.

  19. Installed performance analysis of radar antenna systems

    Microsoft Academic Search

    Jacob J. Kim; Oren B. Kesler

    1998-01-01

    If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Previously, most radar antennas were designed and tested in a clean antenna environment, i.e., there are no near field scattering from host structures, or radome effects. However, these higher order effects are a matter of increasing concern with added performance demands in

  20. Performance analysis of radar antenna systems

    Microsoft Academic Search

    J. J. Kim; O. B. Kesler

    1999-01-01

    If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Until recently, most radar antennas were designed and tested in a clean antenna environment, i.e., there is no near field scattering from host structures or radome effects. However, these higher order effects are the matter of increasing concern with added performance demands

  1. Environmental effects on airborne radar performance

    Microsoft Academic Search

    William A. Skillman

    2011-01-01

    A radar is designed to meet customer specifications of range performance, angle accuracy, etc. However, an airborne radar must operate in an environment which may be different from the assumptions used in writing the performance specification. In an aircraft installation, the radar antenna is protected from the atmospheric environment by a radome which may introduce distortions and reflections of the

  2. 46 CFR 15.815 - Radar observers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...vessels of 300 gross tons or over which are radar equipped, shall hold an endorsement...

  3. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

  4. 46 CFR 15.815 - Radar observers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...vessels of 300 gross tons or over which are radar equipped, shall hold an endorsement...

  5. 46 CFR 167.40-40 - Radar.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

  6. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

  7. 46 CFR 130.310 - Radar.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

  8. 46 CFR 130.310 - Radar.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

  9. 46 CFR 108.717 - Radar.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar. 108.717 Section 108.717 Shipping...Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1...coastwise service must have— (a) A marine radar system for surface navigation; and...

  10. 46 CFR 184.404 - Radars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

  11. 46 CFR 11.480 - Radar observer.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar observer. 11.480 Section 11.480...Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter...

  12. 46 CFR 184.404 - Radars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

  13. 46 CFR 167.40-40 - Radar.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

  14. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

  15. 46 CFR 108.717 - Radar.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar. 108.717 Section 108.717 Shipping...Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1...coastwise service must have— (a) A marine radar system for surface navigation; and...

  16. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

  17. 46 CFR 11.480 - Radar observer.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar observer. 11.480 Section 11.480...Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter...

  18. Radar Technology Applied to Air Traffic Control

    Microsoft Academic Search

    WILLIAM W. SHRADER

    1973-01-01

    Use of primary radars for air traffic control (ATC) is discussed. The location and the parameters of various ATC radars are described. The clutter environment (land clutter, birds, automobiles, and weather) has had a major impact on the configuration of these radars. Signal-processing techniques and antenna techniques utilized to cope with the clutter are described. Future signal-processing techniques for the

  19. Radar target classification of commercial aircraft

    Microsoft Academic Search

    ANTHONY ZYWECK; ROBERT E. BOGNER

    1996-01-01

    With the increased availability of coherent wideband radars there has been a renewed interest in radar target recognition. A large bandwidth gives high resolution in range which means target discrimination may be possible. Coherence makes cross-range resolution and radar images possible. Some of the problems of classifying high resolution range profiles (HRRPs) are examined and simple preprocessing techniques which may

  20. The nature of bistatic and multistatic radar

    Microsoft Academic Search

    Wang Beide

    2001-01-01

    Bistatic and multistatic radar has some properties which are completely different from current monostatic radar. Some special properties that are closely related to tactical applications are derived. Through overall analysis, we believe that this will become one of the most important military radar systems

  1. Fifty years of bistatic and multistatic radar

    Microsoft Academic Search

    J. I. Glaser

    1986-01-01

    The article begins with a review of bistatic and multistatic radars, including the simultaneous introduction of radar technology in several countries during the 1930s and the various areas of technology development pursued by those countries. Technical descriptions are presented of nine different experimental systems. The article continues with a discussion of the potential military and nonmilitary advantages of bistatic radars

  2. Noise modulated multistatic surveillance radar concept

    Microsoft Academic Search

    Vesa-Jukka Salminen; Timo Lensu; Pekka Eskelinen; Simo Mertanen

    2006-01-01

    Noise modulated surveillance radars have many desirable properties. However, practical problems with signal processing and system design have inhibited noise modulated radars to become common. Fast improving signal processing will probably change this in future. We have studied what kind of noise modulated radar might be realistic in 15 years. Advantages are good LPI, good ECCM, good ARM avoidance, good

  3. Course Syllabus Course name: Radar Meteorology

    E-print Network

    Course Syllabus Course name: Radar Meteorology Course number: AT741 Instructor: Prof. Steven a foundational understanding of radar meteorology. Topics presented include microwave scattering theory, Doppler is to provide the student with a working knowledge of radar meteorology including applications to remote sensing

  4. Radar Soundings of the Ionosphere of Mars

    E-print Network

    Gurnett, Donald A.

    Radar Soundings of the Ionosphere of Mars D. A. Gurnett,1 * D. L. Kirchner,1 R. L. Huff,1 D. D4 We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types

  5. MIMO Phased-Array for SMTI Radar

    Microsoft Academic Search

    Jameson Bergin; Steven McNeil; Linda Fomundam; Peter A. Zulch

    2008-01-01

    Waveform diversity techniques for radar have gained considerable interest over the past several years. Novel radar waveforms have been proposed to improve detection performance and metric accuracy (i.e., angle estimation performance). This paper explores the potential for using a waveform diversity technique known as multiple input, multiple output (MIMO) radar to improve the detection performance of slow moving surface targets

  6. APPLICATION OF SENSOR SCHEDULING CONCEPTS TO RADAR

    E-print Network

    Nehorai, Arye

    Chapter 10 APPLICATION OF SENSOR SCHEDULING CONCEPTS TO RADAR William Moran University of Melbourne time illustrating the ideas on sensor schedul- ing in a specific context: that of a radar system. A typical pulse radar system operates by illuminating a scene with a short pulse of electromagnetic energy

  7. Dual-use air traffic control radar

    Microsoft Academic Search

    Lewis Buckler

    1998-01-01

    During the past seven years the Federal Aviation Administration has had a research program called the Terminal Area Surveillance System (TASS) to develop the next generation airport surveillance radar. At present the FAA has two radars for aircraft and weather surveillance at the major airports. One of these radars, the ASR-9, is for aircraft surveillance and rain intensity. The other,

  8. ESTIMATING HYDROGEOLOGIC PARAMETERS FROM RADAR DATA

    Microsoft Academic Search

    Charles T. Young

    Radar reflections for a layered medium are dependant on the dielectric constants of the layers, which is closely linked to saturated porosity, and more loosely to hydraulic conductivity. Radar data have been obtained at a site where hydraulic conductivity has been measured in great detail. The radar cross section from the site clearly shows layering within the section, and it

  9. AESA upgrade option for Eurofighter Captor radar

    Microsoft Academic Search

    M. Barclay; U. Pietzschmann; G. Gonzalez; P. Tellini

    2008-01-01

    The Euroradar consortium has successfully developed and demonstrated an AESA technology upgrade for the Eurofighter Typhoon Captor radar. This technology demonstrator, designated CAESAR, enables E-scan capability to be fully exploited by the existing Captor radar, while retaining all features and capabilities of the original system. Advanced waveforms, designed and optimised for electronically scanned radar systems, have been evaluated in recent

  10. AESA upgrade option for Eurofighter Captor Radar

    Microsoft Academic Search

    M. Barclay; U. Pietzschmann; G. Gonzalez; P. Tellini

    2010-01-01

    The Euroradar Consortium has successfully developed and demonstrated an Active Electronically Scanned Array (AESA) technology upgrade for the Eurofighter Typhoon Captor Radar. This technology demonstrator, designated Captor Active Electronically Scanned Array Radar (CAESAR), enables E-scan capability to be fully exploited by the existing Captor radar, while retaining all features and capabilities of the original system. Advanced waveforms, designed and optimized

  11. Nonsinusoidal radar signal design for stealth targets

    Microsoft Academic Search

    Nasser J. Mohamed

    1995-01-01

    The detection of stealth point targets challenges the design of conventional radars using sinusoidal carriers since the objective of stealth technology is to reduce the radar cross section (RCS) of targets to a level where the radar receiver cannot detect the target. While there are a number of techniques employing different technologies to reduce the RCS of targets, shaping and

  12. Optimum Radar Parameters for Mapping Soil Moisture

    Microsoft Academic Search

    Fawwaz Ulaby; Percy Batlivala

    1976-01-01

    The radar response to soil moisture content was experimentally determined for each of three bare fields with considerably different surface roughnesses at eight frequencies in the 2-8 GHz band for HH and VV polarizations. Analysis of the data indicates that the effect of roughness on the radar backscattering coefficient can be minimized by proper choice of the radar parameters. If,

  13. Overview of hydros radar soil moisture algorithm

    Microsoft Academic Search

    Yunjin Kim; Jakob van Zyl

    2005-01-01

    In this paper, we will describe the Hydros algorithms to derive soil moisture from L-band polarimetric radar measurements. The baseline Hydros radar algorithm to estimate soil moisture is composed of three steps: land classification, preliminary soil moisture estimation, and final time-series improvement. Before soil moisture is estimated using Hydros radar data, each pixel will be classified in order to apply

  14. Hybrid array architectures for BMD radar systems

    Microsoft Academic Search

    J. Frank; J. D. Richards; A. Agrawal

    2003-01-01

    The proliferation of long range ballistic missiles has increased the need for radars capable of supporting early midcourse and ascent phase intercepts. In order to support these early midcourse and ascent phase intercepts, the ballistic missile defense (BMD) radar should be forward deployed. While a sea-based capability can be forward deployed, an easily transportable ground-based radar would be advantageous in

  15. Space Radar Image of Colombian Volcano

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a radar image of a little known volcano in northern Colombia. The image was acquired on orbit 80 of space shuttle Endeavour on April 14, 1994, by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). The volcano near the center of the image is located at 5.6 degrees north latitude, 75.0 degrees west longitude, about 100 kilometers (65 miles) southeast of Medellin, Colombia. The conspicuous dark spot is a lake at the bottom of an approximately 3-kilometer-wide (1.9-mile) volcanic collapse depression or caldera. A cone-shaped peak on the bottom left (northeast rim) of the caldera appears to have been the source for a flow of material into the caldera. This is the northern-most known volcano in South America and because of its youthful appearance, should be considered dormant rather than extinct. The volcano's existence confirms a fracture zone proposed in 1985 as the northern boundary of volcanism in the Andes. The SIR-C/X-SAR image reveals another, older caldera further south in Colombia, along another proposed fracture zone. Although relatively conspicuous, these volcanoes have escaped widespread recognition because of frequent cloud cover that hinders remote sensing imaging in visible wavelengths. Four separate volcanoes in the Northern Andes nations ofColombia and Ecuador have been active during the last 10 years, killing more than 25,000 people, including scientists who were monitoring the volcanic activity. Detection and monitoring of volcanoes from space provides a safe way to investigate volcanism. The recognition of previously unknown volcanoes is important for hazard evaluations because a number of major eruptions this century have occurred at mountains that were not previously recognized as volcanoes. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companiesfor the German space agency, Deutsche Agentur fuer Raumfahrtange-legenheiten (DARA), and the Italian space agency,Agenzia SpazialeItaliana (ASI), with the Deutsche Forschungsanstalt fuer Luft undRaumfahrt e.v.(DLR), the major partner in science,operations, and data processing of X-SAR.

  16. Analysis of Active Lava Flows on Kilauea Volcano, Hawaii, Using SIR-C Radar Correlation Measurements

    NASA Technical Reports Server (NTRS)

    Zebker, H. A.; Rosen, P.; Hensley, S.; Mouginis-Mark, P. J.

    1995-01-01

    Precise eruption rates of active pahoehoe lava flows on Kilauea volcano, Hawaii, have been determined using spaceborne radar data acquired by the Space Shuttle Imaging Radar-C (SIR-C). Measurement of the rate of lava flow advance, and the determination of the volume of new material erupted in a given period of time, are among the most important observations that can be made when studying a volcano.

  17. Radar test range design considerations

    NASA Astrophysics Data System (ADS)

    Sofianos, D.

    1980-04-01

    This report presents considerations for and the preliminary design of a synthetic aperture RADAR (SAR) test range. The purpose is to present a methodology and conceptual design for a Flexible Test Bed (FTB) digital processor operational test. The objectives of this operational test are to: (1) determine whether the processor modifications improved image quality, (2) establish a processor performance baseline, and (3) determine whether the system will attain desired levels of probability of detection. It is assumed that SAI would develop a test design while GAC will fabricate and install the required radar test range.

  18. Oxalate: Effect on calcium absorbability

    SciTech Connect

    Heaney, R.P.; Weaver, C.M. (Creighton Univ., Omaha, NE (USA))

    1989-10-01

    Absorption of calcium from intrinsically labeled Ca oxalate was measured in 18 normal women and compared with absorption of Ca from milk in these same subjects, both when the test substances were ingested in separate meals and when ingested together. Fractional Ca absorption from oxalate averaged 0.100 +/- 0.043 when ingested alone and 0.140 +/- 0.063 when ingested together with milk. Absorption was, as expected, substantially lower than absorption from milk (0.358 +/- 0.113). Nevertheless Ca oxalate absorbability in these women was higher than we had previously found for spinach Ca. When milk and Ca oxalate were ingested together, there was no interference of oxalate in milk Ca absorption and no evidence of tracer exchange between the two labeled Ca species.

  19. Radar volcano monitoring system in Iceland

    NASA Astrophysics Data System (ADS)

    Arason, Þórður; Yeo, Richard F.; Sigurðsson, Geirfinnur S.; Pálmason, Bolli; von Löwis, Sibylle; Nína Petersen, Guðrún; Bjornsson, Halldór

    2013-04-01

    Weather radars are valuable instruments in monitoring explosive volcanic eruptions. Temporal variations in the eruption strength can be monitored as well as variations in plume and ash dispersal. Strength of the reflected radar signal of a volcanic plume is related to water content and droplet sizes as well as type, shape, amount and the grain size distribution of ash. The Icelandic Meteorological Office (IMO) owns and operates three radars and one more is planned for this radar volcano monitoring system. A fixed position 250 kW C-band weather radar was installed in 1991 in SW-Iceland close to Keflavík International Airport, and upgraded to a doppler radar in 2010. In cooperation with the International Civil Aviation Organization (ICAO), IMO has recently invested in two mobile X-band radars and one fixed position C-band radar. The fixed position 250 kW doppler C-band weather radar was installed in April 2012 at Fljótsdalsheiði, E-Iceland, and in June 2012 IMO received a mobile 65 kW dual-polarization doppler X-band radar. Early in 2013 IMO will acquire another mobile radar of the same type. Explosive volcanic eruptions in Iceland during the past 22 years were monitored by the Keflavík radar: Hekla 1991, Gjálp 1996, Grímsvötn 1998, Hekla 2000, Grímsvötn 2004, Eyjafjallajökull 2010 and Grímsvötn 2011. Additionally, the Grímsvötn 2011 eruption was mointored by a mobile X-band radar on loan from the Italian Civil Protection Authorities. Detailed technical information is presented on the four radars with examples of the information acquired during previous eruptions. This expanded network of radars is expected to give valuable information on future volcanic eruptions in Iceland.

  20. Electron absorbed dose measurements in LINACs by thermoluminescent dosimeters.

    PubMed

    Cortés, J Rodríguez; Romero, R Alvarez; Nieto, J Azorín; Montalvo, T Rivera

    2014-01-01

    In this work, electron absorbed doses measurements in radiation therapy (RT) were obtained. Radiation measurements were made using thermoluminescent dosimeters of calcium sulfate doped with dysprosium (CaSO4:Dy) and zirconium oxide (ZrO2). TL response calibration was obtained by irradiating TLDs and a Farmer cylindrical ionization chamber PTW 30013 at the same time. Each TL material showed a typical glow curve according to each material. Both calcium sulfate doped with dysprosium and zirconium oxide exhibited better light intensity to high energy electron beam compared with lithium fluoride. TL response as a function of absorbed dose was analyzed. TL response as a function of high energy electron beam was also studied. PMID:24060149

  1. Beam Pipe HOM Absorber for 750 MHz RF Cavity Systems

    SciTech Connect

    Johnson, Rolland; Neubauer, Michael

    2014-10-29

    This joint project of Muons, Inc., Cornell University and SLAC was supported by a Phase I and Phase II grant monitored by the SBIR Office of Science of the DOE. Beam line HOM absorbers are a critical part of future linear colliders. The use of lossy materials at cryogenic temperatures has been incorporated in several systems. The design in beam pipes requires cylinders of lossy material mechanically confined in such a way as to absorb the microwave energy from the higher-order modes and remove the heat generated in the lossy material. Furthermore, the potential for charge build-up on the surface of the lossy material requires the conductivity of the material to remain consistent from room temperature to cryogenic temperatures. In this program a mechanical design was developed that solved several design constraints: a) fitting into the existing Cornell load vacuum component, b) allowing the use of different material compositions, c) a thermal design that relied upon the compression of the lossy ceramic material without adding stress. Coating experiments were performed that indicated the design constraints needed to fully implement this approach for solving the charge build-up problem inherent in using lossy ceramics. In addition, the ACE3P program, used to calculate the performance of lossy cylinders in beam pipes in general, was supported by this project. Code development and documentation to allow for the more wide spread use of the program was a direct result of this project was well.

  2. Electromagnetic scattering by pyramidal and wedge absorber

    NASA Technical Reports Server (NTRS)

    Dewitt, Brian T.; Burnside, Walter D.

    1988-01-01

    Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for near-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength.

  3. L-band radar scattering from grass

    NASA Technical Reports Server (NTRS)

    Chauhan, N.; O'Neill, P.; Le Vine, D.; Lang, R.; Khadr, N.

    1992-01-01

    A radar system based on a network analyzer has been developed to study the backscatter from vegetation. The radar is operated at L-band. Radar measurements of a grass field were made in 1991. The radar returns from the grass were measured at three incidence angles. Ground truth and canopy parameters such as blade and stem dimensions, moisture content of the grass and the soil, and blade and stem density, were measured. These parameters are used in a distorted Born approximation model to compute the backscatter coefficients from the grass layer. The model results are compared with the radar data.

  4. Radar in the wake of WARC

    NASA Astrophysics Data System (ADS)

    Tompkins, R. D.

    1981-08-01

    The World Administrative Radio Conference of 1979 (WARC-79) will have a significant effect on the design, development, and operation of radar systems. This paper discusses the changes in the Table of Frequency Allocations which will affect radar and notes some of the problems which will be faced by the radar community in maintaining system performance requirements. An urgent need is shown for expanding the participation by radar developers in the affairs of the International Radio Consultative Committee (CCIR). This participation is essential to create and maintain a technical basis for radar which will define spectrum needs, examine spectrum usage, and describe techniques for efficient spectrum utilization within the International Telecommunications Union (ITU).

  5. Evaluation of Composite Electromagnetic Wave Absorber Made of Isolated Ni-Zn Ferrite or Permalloy

    Microsoft Academic Search

    Kenji Sakai; Kiyohiro Hiraki; Shinzo Yoshikado

    2007-01-01

    It has been found that if magnetic materials isolate in dielectric medium, permeability of composite material doesn't obey Lichtenecker's law, which is well known to explain permeability and permittivity of composite material. This characteristic leads to absorption of electromagnetic wave above 1 GHz. We proposed isolated model to simulate the frequency dispersion of permeability and developed composite electromagnetic wave absorber

  6. Metal Oxide/Zeolite Combination Absorbs H2S

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E.; Sharma, Pramod K.

    1989-01-01

    Mixed copper and molybdenum oxides supported in pores of zeolite found to remove H2S from mixture of gases rich in hydrogen and steam, at temperatures from 256 to 538 degree C. Absorber of H2S needed to clean up gas streams from fuel processors that incorporate high-temperature steam reformers or hydrodesulfurizing units. Zeolites chosen as supporting materials because of their high porosity, rigidity, alumina content, and variety of both composition and form.

  7. Permittivity of highly absorbing oxide ceramics in millimeter waves

    Microsoft Academic Search

    Mohammed N. Afsar; King Wang; Peter Liu; Konstantin A. Korolev

    2008-01-01

    Complex dielectric permittivity of highly absorbing oxide ceramics have been studied in a broadband millimeter wave frequency range for the first time. Transmittance and reflectance measurements have been performed using a free space quasi-optical spectrometer, equipped with a set of high power backward wave oscillators, tunable in Q-, V- and W-frequency bands. Ceramic materials have found to be almost non-transparent

  8. Recycling of waste tyre rubber into oil absorbent

    Microsoft Academic Search

    B. Wu; M. H. Zhou

    2009-01-01

    The abundant and indiscriminant disposal of waste tyres has caused both health and environmental problems. In this work, we provide a new way to dispose off waste tyres by reusing the waste tyre rubber (WTR) for oil absorptive material production. To investigate this feasibility, a series of absorbents were prepared by graft copolymerization-blending method, using waste tyre rubber and 4-tert-butylstyrene

  9. Absorbable staples in continent ileal urinary pouch.

    PubMed

    Bonney, W W; Robinson, R A

    1990-01-01

    Continent ileal urinary reservoirs were created in dogs to study absorbable surgical staples. Within each pouch, certain controlled observations were possible. The staples and chemically similar polyglactin absorbable sutures caused almost identical tissue reactions. The staples outlasted the sutures, probably because of greater size. Inverted and everted staple closures worked equally well. It appears feasible to consider clinical urinary diversion with absorbable staples, a time-saving method. PMID:2404367

  10. Physical Properties of Volcanic Deposits on Venus from Radar Polarimetry

    NASA Technical Reports Server (NTRS)

    Carter, Lynn M.; Campbell, Donald B.; Campbell, Bruce A.

    2005-01-01

    Studies of the morphology and radar properties of volcanic deposits can aid in understanding their differences and formation. On Venus, volcanoes range in size from large highland edifices, such as Theia Mons, to small shields and domes which are often found in groups of tens to hundreds. In plains regions, windstreaks are sometimes found near shield fields, suggesting that there may be fine grained deposits associated with the volcanoes. Previous studies of Bell Regio suggest the presence of fine-grained material in a low dielectric constant triangular shaped region on the flank of Tepev Mons, which may be crater ejecta or a pyroclastic deposit spread westward by wind. The eastern caldera on Tepev Mons shows a steep trend in backscattered power with incidence angle and has high RMS-slopes, implying a finegrained covering such as ash. Radar waves can easily penetrate smooth mantling layers such as ash and aeolian deposits. If a radar system can measure two orthogonal polarizations, it is possible to detect subsurface scattering and infer the presence of surficial deposits. The Magellan spacecraft could only measure one polarization and was therefore not able to fully characterize the polarization state of the radar echoes. We compare Arecibo dual-polarization data for Venus to Magellan images and emissivity data to investigate the physical properties of volcanic deposits.

  11. Enhanced Weather Radar (EWxR) System

    NASA Technical Reports Server (NTRS)

    Kronfeld, Kevin M. (Technical Monitor)

    2003-01-01

    An airborne weather radar system, the Enhanced Weather Radar (EWxR), with enhanced on-board weather radar data processing was developed and tested. The system features additional weather data that is uplinked from ground-based sources, specialized data processing, and limited automatic radar control to search for hazardous weather. National Weather Service (NWS) ground-based Next Generation Radar (NEXRAD) information is used by the EWxR system to augment the on-board weather radar information. The system will simultaneously display NEXRAD and on-board weather radar information in a split-view format. The on-board weather radar includes an automated or hands-free storm-finding feature that optimizes the radar returns by automatically adjusting the tilt and range settings for the current altitude above the terrain and searches for storm cells near the atmospheric 0-degree isotherm. A rule-based decision aid was developed to automatically characterize cells as hazardous, possibly-hazardous, or non-hazardous based upon attributes of that cell. Cell attributes are determined based on data from the on-board radar and from ground-based radars. A flight path impact prediction algorithm was developed to help pilots to avoid hazardous weather along their flight plan and their mission. During development the system was tested on the NASA B757 aircraft and final tests were conducted on the Rockwell Collins Sabreliner.

  12. Mode trap for absorbing transverse modes of an accelerated electron beam

    DOEpatents

    Chojnacki, E.P.

    1994-05-31

    A mode trap to trap and absorb transverse modes formed by a beam in a linear accelerator includes a waveguide having a multiplicity of electrically conductive (preferably copper) irises and rings, each iris and ring including an aperture, and the irises and rings being stacked in a side-by-side, alternating fashion such that the apertures of the irises and rings are concentrically aligned. An absorbing material layer such as a dielectric is embedded in each iris and ring, and this absorbing material layer encircles, but is circumferentially spaced from its respective aperture. Each iris and ring includes a plurality of circumferentially spaced slots around its aperture and extending radially out toward its absorbing material layer. 9 figs.

  13. Cognitive radar: A way forward

    Microsoft Academic Search

    Michael Wicks

    2011-01-01

    The desire to autonomously anticipate, find, fix, track, target, engage, and assess, anything, anytime, anywhere (AF2T2EA4) in spectrally dense environments will require changes to how we build, modify, and deploy radar and radio frequency systems. These spectrally dense environments coupled with the twenty-first century threat are already causing havoc throughout the world.

  14. An interferometer tracking radar system

    NASA Technical Reports Server (NTRS)

    Broderick, R. F.

    1969-01-01

    Fine tuning acquisition and tracking interferometer radar system uses a first antenna array of at least three receiving antennas. Array includes a reference antenna, a coarse tuning antenna, and a fine tuning antenna aligned on a receiving axis. Short range rendezvous system provides increased position accuracy.

  15. Spatial Coverage of Radar Reflectors

    Microsoft Academic Search

    Daniel Levine; William H. Welch

    1964-01-01

    Passive reflectors may be employed to enhance the radar return of a space vehicle for some phases of tracking, as in orbital rendezvous. Contour charts prepared on a suitable base grid provide an objective means of evaluating the spatial coverage of different designs for this application. The superiority of a circular corner reflector over square or triangular designs is demonstrated

  16. CFAR detection for multistatic radar

    Microsoft Academic Search

    Vahideh Amanipour; Ali Olfat

    2011-01-01

    In this paper a multistatic radar system with n transmitters and one receiver is considered and several constant false alarm rate (CFAR) algorithms for detection are introduced. The decision statistics of the proposed detectors are the sum of the n largest returning signals in an array of N+n range cells. It is shown that the proposed decision statistic satisfies the

  17. Solid-state radar transmitters

    Microsoft Academic Search

    E. D. Ostroff; M. Borkowski; H. Thomas; J. Curtis

    1985-01-01

    The technology and design procedures for introducing transistors into radio transmitters are discussed. The design characteristics of solid-state radar transmitters are described, with emphasis given to power amplifier\\/modules and devices for summing the output power in space or in an output combiner. Some design issues related to power supplies, pulse waveform amplitude regulation; reliability; and cost; and also considered. Some

  18. Pioneer Venus radar mapper experiment

    USGS Publications Warehouse

    Pettengill, G.H.; Ford, P.G.; Brown, W.E.; Kaula, W.M.; Keller, C.H.; Masursky, H.; McGill, G.E.

    1979-01-01

    Altimetry and radar scattering data for Venus, obtained from 10 of the first 13 orbits of the Pioneer Venus orbiter, have disclosed what appears to be a rift valley having vertical relief of up to 7 kilometers, as well as a neighboring, gently rolling plain. Planetary oblateness appears unlikely to exceed 112500 and may be substantially smaller. Copyright ?? 1979 AAAS.

  19. Test equipment for coherent radar

    Microsoft Academic Search

    D. B. Leeson; W. K. Saunders

    1974-01-01

    Test equipment for pulsed Doppler and CW coherent radar is described. Equipment developed for testing the Vulcan tracking system is discussed, and the test procedure is outlined. The Vulcan equipment provides measurements of STAMO quality, the additive noise contributed by the sideband modulator and klystron amplifier, limitations on subclutter visibility and the minimum detected signal in the receiving chain, lock

  20. Radar Imagery of Oil Slicks

    Microsoft Academic Search

    R. O. Pilon; C. G. Purves

    1973-01-01

    A joint agency controlled oil slick experiment, sponsored by the United States Coast Guard, was conducted in the Pacific Ocean in the Fall of 1970. The Naval Research Laboratory's synthetic aperature radar was used to detect and monitor the slicks at frequencies of 428, 1228, 4455, and 8910 MHz during the low sea state conditions encountered. At frequencies of 1228

  1. UK airborne AESA radar research

    Microsoft Academic Search

    Stephen Moore

    2010-01-01

    This reviews current UK airborne active electronically scanned array (AESA) designs, discusses current trends toward higher digitisation and multi-function aperture concepts, and details key future challenges that this technology faces. Specifically, we discuss applications to fast-jets. Key requirements are for higher levels of digitisation to provide the performance required in ECCM, STAP, GMTI, and ESM modes. Building radar systems with

  2. Fractal radar scattering from soil.

    PubMed

    Oleschko, Klaudia; Korvin, Gabor; Figueroa, Benjamin; Vuelvas, Marco Antonio; Balankin, Alexander S; Flores, Lourdes; Carreón, Dora

    2003-04-01

    A general technique is developed to retrieve the fractal dimension of self-similar soils through microwave (radar) scattering. The technique is based on a mathematical model relating the fractal dimensions of the georadargram to that of the scattering structure. Clear and different fractal signatures have been observed over four geosystems (soils and sediments) compared in this work. PMID:12786363

  3. Radar attenuation in desert soil

    Microsoft Academic Search

    Gary Koh

    2008-01-01

    Soil properties make a significant impact in the observed responses of various sensors for subsurface target detection. Ground penetrating radars (GPRs) have been extensively researched as a tool for subsurface target detection. A key soil parameter of interest for evaluating GPR performance is the soil attenuation rate. The information about the soil attenuation rate coupled with target properties (size, shape,

  4. Fractal radar scattering from soil

    Microsoft Academic Search

    Klaudia Oleschko; Gabor Korvin; Benjamin Figueroa; Marco Antonio Vuelvas; Alexander S. Balankin; Lourdes Flores; Dora Carreón

    2003-01-01

    A general technique is developed to retrieve the fractal dimension of self-similar soils through microwave (radar) scattering. The technique is based on a mathematical model relating the fractal dimensions of the georadargram to that of the scattering structure. Clear and different fractal signatures have been observed over four geosystems (soils and sediments) compared in this work.

  5. Statement of capabilities: Micropower Impulse Radar (MIR) technology applied to mine detection and imaging

    SciTech Connect

    Azevedo, S.G.; Gavel, D.T.; Mast, J.E.; Warhus, J.P.

    1995-03-13

    The Lawrence Livermore National Laboratory (LLNL) has developed radar and imaging technologies with potential applications in mine detection by the armed forces and other agencies involved in demining efforts. These new technologies use a patented ultra-wideband (impulse) radar technology that is compact, low-cost, and low power. Designated as Micropower Impulse Radar, these compact, self-contained radars can easily be assembled into arrays to form complete ground penetrating radar imaging systems. LLNL has also developed tomographic reconstruction and signal processing software capable of producing high-resolution 2-D and 3-D images of objects buried in materials like soil or concrete from radar data. Preliminary test results have shown that a radar imaging system using these technologies has the ability to image both metallic and plastic land mine surrogate targets buried in 5 to 10 cm of moist soil. In dry soil, the system can detect buried objects to a depth of 30 cm and more. This report describes LLNL`s unique capabilities and technologies that can be applied to the demining problem.

  6. Planetary Radars Operating Centre PROC

    NASA Astrophysics Data System (ADS)

    Catallo, C.; Flamini, E.; Seu, R.; Alberti, G.

    2007-12-01

    Planetary exploration by means of radar systems, mainly using Ground Penetrating Radars (GPR) plays an important role in Italy. Numerous scientific international space programs are currently carried out jointly with ESA and NASA by Italian Space Agency, the scientific community and the industry. Three important experiments under Italian leadership ( designed and manufactured by the Italian industry), provided by ASI either as contribution to ESA programs either within a NASA/ASI joint venture framework, are now operating: MARSIS on-board Mars Express, SHARAD on-board Mars Reconnaissance Orbiter and CASSINI Radar on-board Cassini spacecraft. In order to support all the scientific communities, institutional customers and experiment teams operation three Italian dedicated operational centers have been realized, namely SHOC, (Sharad Operating Centre), MOC (Marsis Operating Center) and CASSINI PAD ( Processing Altimetry Data). Each center is dedicated to a single instrument management and control, data processing and distribution. Although they had been conceived to operate autonomously and independently one from each other, synergies and overlaps have been envisaged leading to the suggestion of a unified center, the Planetary Radar Processing Center (PROC). PROC is conceived in order to include the three operational centers, namely SHOC, MOC and CASSINI PAD, either from logistics point of view and from HW/SW capabilities point of view. The Planetary Radar Processing Center shall be conceived as the Italian support facility to the scientific community for on-going and future Italian planetary exploration programs. Therefore, scalability, easy use and management shall be the design drivers. The paper describes how PROC is designed and developed, to allow SHOC, MOC and CASSINI PAD to operate as before, and to offer improved functionalities to increase capabilities, mainly in terms of data exchange, comparison, interpretation and exploitation. Furthermore, in the frame of an operative experimental platform, where a specific payload ( to be developed by the Italian Industry) a GPR will be accommodated on-board the Italian Space Agency stratospheric balloon and the data analysed by PROC; as a minimum two flight campaigns over polar regions are foreseen. The system shall be capable of acquiring radar data upon scientists requests in order to help them refine their models, experiment new algorithms, improve data interpretation capabilities. The paper also describes how the system will be integrated in the PROC, sharing the operational resources and aiding scientists to increase their knowledge in the field of surface radar sounding. A specific PROC Web facility is foreseen to allow data gathering, request submission, data exchange and dissemination.

  7. Polarization-insensitive FSS-based perfect metamaterial absorbers for GHz and THz frequencies

    NASA Astrophysics Data System (ADS)

    Sabah, Cumali; Dincer, Furkan; Karaaslan, Muharrem; Unal, Emin; Akgol, Oguzhan

    2014-04-01

    New perfect frequency selective surface (FSS) metamaterial absorbers (MAs) based on resonator with dielectric configuration are numerically presented and investigated for both microwave and terahertz frequency ranges. Also, to verify the behaviors of the FSS MAs, one of the MAs is experimentally analyzed and tested in the microwave frequency range. Suggested FSS MAs have simple configuration which introduces flexibility to adjust their FSS metamaterial properties and to rescale the structure easily for any desired frequency range. There is no study which simultaneously includes microwave and terahertz absorbers in a single design in the literature. Besides, numerical simulations verify that the FSS MAs could achieve very high absorption levels at wide angles of incidence for both transverse electric and transverse magnetic waves. The proposed FSS MAs and their variations enable many potential application areas in radar systems, communication, stealth technologies, and so on.

  8. The intergration of liquid and solid muon absorbers into afocusing magnet of a muon cooling channel

    SciTech Connect

    Green, M.A.; Black, E.L.; Cummings, M.A.; Kaplan, D.M.; Ishimoto,S.; Cobb, J.H.; Lau, W.; Yang, S.; Palmer, R.B.

    2003-05-01

    This report describes how one can integrate the muonabsorber with the focusing coils of a SFOFO muon cooling channel [1]. Theabsorber material must be a low Z material that reduces the muon momentumwith minimum scattering. The best materials to use for muon ionizationcooling absorbers are hydrogen, helium, lithium hydride, lithium, andberyllium. Hydrogen or helium in an absorber would normally be in theliquid state. Lithium hydride, lithium, and beryllium would normally bein the solid state. This report limits the absorber materials discussedto hydrogen, helium, lithium, and beryllium. In order to achieve the samelevel of ionization cooling with a solid absorber as a liquid hydrogenabsorber, the beta of the muon beam must be reduced more than a factor oftwo. This affects both the designs of the absorber and the magnet aroundit. Reducing the beam beta reduces the momentum acceptance of thechannel. Integration of a liquid hydrogen absorber and solid absorberswith a superconducting focusing solenoid is discussed. The choice ofabsorber material affects the design of the superconducting focusingmagnet and the superconductor that is used to generate the magneticfield.

  9. The Basic Radar Altimetry Toolbox

    NASA Astrophysics Data System (ADS)

    Benveniste, Jerome

    J. Benveniste (1), V. Rosmorduc (2) S. Niemeijer (3), N. Picot (4) (1) European Space Agency (2) CLS, France, (3) STCorp, NL (4) CNES, France (www.altimetry.info) The field of satellite radar altimetry has matured to a point where it is now time to encourage a multimission approach (between various altimetry systems) and conceive an "all-altimeter" toolbox and tutorial. Such an integrated approach and view is vital not only for assessing the current status of what offers altimeter products but also to show the system and consistency with the past. The Basic Radar Altimetry Toolbox (BRAT) is a collection of tools, tutorials and documents designed to facilitate the use of radar altimetry data for altimetry users, experienced as well as beginners, and particularly the users of the upcoming CryoSat mission. It is able . to read most distributed radar altimetry data, from ERS-1 and 2, Topex/Poseidon, Geosat Follow-on, Jason-1, Envisat, and the future Cryosat missions, . to perform some processing, data editing and statistic, . and to visualise the results. A version 2 is being developed with additional visualisation features such as waveform viewing. Also, a release for the MacOS is planned. As part of the Toolbox, a Radar Altimetry Tutorial gives general information about altimetry, the technique involved and its applications, as well as an overview of past, present and future missions, including information on how to access data and additional software and documentation. It also presents a series of data use cases, covering all uses of altimetry over ocean, cryosphere and land, showing the basic methods for some of the most frequent manners of using altimetry data BRAT is being developed under contract with ESA and CNES. It is available at http://www.altimetry.info

  10. Recycling of waste tyre rubber into oil absorbent.

    PubMed

    Wu, B; Zhou, M H

    2009-01-01

    The abundant and indiscriminant disposal of waste tyres has caused both health and environmental problems. In this work, we provide a new way to dispose off waste tyres by reusing the waste tyre rubber (WTR) for oil absorptive material production. To investigate this feasibility, a series of absorbents were prepared by graft copolymerization-blending method, using waste tyre rubber and 4-tert-butylstyrene (tBS) as monomers. Divinylbenzene (DVB) and benzoyl peroxide (BPO) were employed as crosslinker and initiator, respectively. The existence of graft-blends (WTR-g-tBS) was determined by FTIR spectrometry and verified using thin-layer chromatography (TLC). In addition, the thermal properties of WTR-g-tBS were confirmed by a thermogravimetric analyzer (TGA). Oil absorbency of the grafted-blends increased with increases in either feed ratio of WTR to tBS or DVB concentration. This absorbency reached a maximum of 24.0gg(-1) as the feed ratio and DVB concentration were 60/40 and 1wt%, respectively, after which it decreased. At other ratios and concentrations the absorbency decreased. The gel fraction of grafted-blends increased with increasing concentration of DVB. Oil-absorption processes in pure toluene and crude oil diluted with toluene were found to adhere to first-order absorption kinetics. Furthermore, the oil-absorption rate in diluted crude oil was observed to be lower than pure toluene. PMID:18455384

  11. Photothermal response of near-infrared-absorbing NanoGUMBOS.

    PubMed

    Dumke, Jonathan C; Qureshi, Ammar; Hamdan, Suzana; El-Zahab, Bilal; Das, Susmita; Hayes, Daniel J; Boldor, Dorin; Rupnik, Kresimir; Warner, Isiah M

    2014-01-01

    The photothermal properties of several near-infrared-absorbing nanoparticles derived from group of uniform materials based on organic salts (GUMBOS) and composed of cationic dyes coupled with biocompatible anions are evaluated. These nanoparticles were synthesized using a reprecipitation method performed at various pH values: 2.0, 5.0, 7.0, 9.0, and 11.0. The cations for the nanoparticles derived from GUMBOS (nanoGUMBOS), [1048] and [1061], have absorbance maxima at wavelengths overlapping with human soft tissue absorbance minima. Near-infrared-absorbing nanoGUMBOS excited with a 1064 nm continuous laser led to heat generation, with an average temperature increase of 20.4 ± 2.7 °C. Although the [1061][Deoxycholate] nanoGUMBOS generated the highest temperature increase (23.7 ± 2.4 °C), it was the least photothermally efficient compound (13.0%) due to its relatively large energy band gap of 0.892 eV. The more photothermally efficient compound [1048][Ascorbate] (64.4%) had a smaller energy band gap of 0.861 eV and provided an average photothermal temperature increase of 21.0 ± 2.1 °C. PMID:24666951

  12. A Monte Carlo evaluation of three Compton camera absorbers.

    PubMed

    Uche, C Z; Round, W H; Cree, M J

    2011-09-01

    We present a quantitative study on the performance of cadmium zinc telluride (CZT), thallium-doped sodium iodide (NaI(Tl)) and germanium (Ge) detectors as potential Compton camera absorbers. The GEANT4 toolkit was used to model the performance of these materials over the nuclear medicine energy range. CZT and Ge demonstrate the highest and lowest efficiencies respectively. Although the best spatial resolution was attained for Ge, its lowest ratio of single photoelectric to multiple interactions suggests that it is most prone to inter-pixel cross-talk. In contrast, CZT, which demonstrates the least positioning error due to multiple interactions, has a comparable spatial resolution with Ge. Therefore, we modelled a Compton camera system based on silicon (Si) and CZT as the scatterer and absorber respectively. The effects of the detector parameters of our proposed system on image resolution were evaluated and our results show good agreement with previous studies. Interestingly, spatial resolution which accounted for the least image degradation at 140.5 keV became the dominant degrading factor at 511 keV, indicating that the absorber parameters play some key roles at higher energies. The results of this study have validated the predictions by An et al. which state that the use of a higher energy gamma source together with reduction of the absorber segmentation to sub-millimetre could achieve the image resolution of 5 mm required in medical imaging. PMID:21710232

  13. Tests of absorbents and solidification techniques for oil wastes

    SciTech Connect

    Lin, M.; MacKenzie, D. R.

    1983-11-01

    A representative of each of six classes of commonly used adsorbents was chosen for a series of tests. After reviewing ASTM and other related standard tests, uncomplicated procedures were developed for carrying out specific tests to determine absorbency for simulated oil waste and for water, under static and simulated transportation (repetitive shock) conditions. The tests were then applied to the six representative absorbents. Solidification tests were performed using these absorbents saturated with oil and loaded to 50% of saturation. The binders used were Portland I cement and Delaware Custom Material (DCM) cement shale silicate. Samples were checked for proper set, and the amounts of free liquid were measured. Another series of tests was performed on samples of simulated oil waste without absorbent, using Portland cement and DCM cement shale silicate. Samples were checked for proper set, free liquid was measured, and compressive strengths were determined. The state-of-the-art parameters were identified which satisfy NRC disposal criteria for solidified radioactive waste. The literature was reviewed for alternative methods of managing oil wastes. Conclusions are drawn on the relative utility of the various methods. 17 references, 3 tables.

  14. A doubly periodic moment method solution for the analysis and design of an absorber covered wall

    NASA Technical Reports Server (NTRS)

    Yang, Chang-Fa; Burnside, Walter D.; Rudduck, Roger C.

    1993-01-01

    The periodic moment method (PMM) solution for scattering from a doubly periodic array of lossy dielectric bodies is developed in this paper. The purpose of this study is to design electromagnetic wedge and pyramidal absorber for low reflectivity so that one can improve the performance of anechoic chamber measurements. The spectral-domain formulation and the moment method volume polarization current approach are applied to obtain the expressions used to determine the scattering from a doubly periodic array of lossy dielectric bodies. Through these studies, some wedge and pyramidal absorber configurations have been designed, fabricated, and then tested in the OSU/ESL compact range measurement facility. In this paper, wedge absorber, commercial pyramidal absorber, and some low-frequency pyramidal absorber designs are presented. By considering the complexity of dealing with real-world material structures, good agreement between calculations and measurements has been obtained.

  15. A uniflow absorbent oil regenerator

    SciTech Connect

    Sidogin, V.P.; Babitsin, S.M.; Brodskii, E.V.; Gulyaev, V.M.; Khomin, V.T.

    1984-01-01

    The uniflow absorbent oil regenerator presented in this article has been developed and introduced at the Dnepropetrovsk Coking Plant in conjunction with the Dnepropetrovsk Chemical and Technological Institute. The body of the device is a convergent duct with a cylindrical neck and a diffuser. A conical oil receptacle and conical inserts are positioned in the convergent duct. A connecting pipe for gas input and a connecting pipe for injecting oil into a conical receptacle are placed on the upper end shield of the body. A swirler made out of inclined vanes which partly overlap inside is placed at the diffuser outlet. A cylinder, contained in a steam jacket with chokes for letting in steam and letting out condensate, is positioned under the diffuser. The gas-removal connecting pipe, mounted on a lower end shield of the device, is partially recessed inside the cylinder, and forms with its inside walls a collector for the annular section which is supplied with a connecting pipe for removal of the liquid phase (polymers).

  16. Alpine radar conversion for LAWR

    NASA Astrophysics Data System (ADS)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this class of radars, because it accounts for the large variability of hydrometeors reflectivity and vertical hydrometeors positioning (echo-top), which is strongly influenced by the high location of the radar. The ARCOM procedure is in addition embedded in a multistep quality control framework, which also includes the calibration on raingauge observations, and can be summarized as follow: 1) correction of both LAWR and raingauge observations for known errors (e.g. magnetron decay and heated-related water loss) 2) evaluation of the local Pearson's correlation coefficient (PCC) as estimator of the linear correlation between raingauge and LAWR observations (logarithmic receiver); 3) computation of the local ACF in the form of the local linear regression coefficient between raingauge and LAWR observations; 4) calibration of the ARCOM, i.e. definition of the parametrization able to reproduce the spatial variability of ACF as function of the local sP, being the PCCs used as weight in the calibration procedure. The resulting calibrated ARCOM finally allows, in any ungauged mountain spot, to convert LAWR observations into precipitation rate. The temporal and the spatial transferability of the ARCOM are evaluated via split-sample and a take-one-out cross validation. The results revealed good spatial transferability and a seasonal bias within 7%, thus opening new opportunities for local range distributed measurements of precipitation in mountain regions.

  17. Absorbance Changes of Carotenoids in Different Solvents

    Microsoft Academic Search

    Lun-Yi Zang; Olaf Sommerburg; Frederik J. G. M van Kuijk

    1997-01-01

    Carotenoids are typically measured in tissues with the high performance liquid chromatography (HPLC) and quantitation is usually done by calibrating with stock solutions in solvents. Four carotenoids including lutein, zeaxanthin, lycopene and ?-carotene were dissolved in hexane and methanol respectively, and their absorbance characteristeris were compared. Lutein shows absorbance spectra that are almost independent of solvents at various concentrations. Spectra

  18. Absorbed radiation dose on LHC interconnects

    E-print Network

    Versaci, R; Vlachoudis, V; CERN. Geneva. ATS Department

    2011-01-01

    Here we present the results of our FLUKA simulations devoted to the evaluation of the peak dose absorbed by the busbar insulator in the LHC Interaction Region 7 interconnects. The peak dose absorbed by the cold magnet coils are also presented.

  19. Proton Absorber Feasibility Study Chris Rogers,

    E-print Network

    McDonald, Kirk

    Proton Absorber ­ Feasibility Study Chris Rogers, ASTeC, Rutherford Appleton Laboratory 14 Sept 2010 #12;Overview We have a problem with secondary protons in the front end Deposit significant Need remote handling (ouch) One way to fix this is using a proton absorber Change in beam power

  20. Method of fabricating a solar absorber panel

    Microsoft Academic Search

    Severson

    1982-01-01

    A low-cost method of fabricating a solar absorber panel for use with a flat plate solar collector system is disclosed in which a plurality of formed elongated substantially u-shaped members are fixed in a predetermined configuration to the reverse side of a single sheet absorber member forming therewith hollow fluid passages or ducts. The fluid duct members are provided with

  1. SYNCHROTRON RADIATION ABSORBERS FOR HADRON COLLIDERS

    Microsoft Academic Search

    P. Bauer; K. Ewald; C. Darve; P. J. Limon; T. Nicol; N. Solyak; I. Terechkine; A. Barcikowski; J. Noonan; R. Rosenberg; E. Rotela; B. Rusthoven; S. Sharma

    We present the results of a design study of synchrotron radiation absorbers, or photon stops, conducted in the context of a recent study of a Very Large Hadron Collider (VLHC), (1). Photon stops protrude into the beam tube at the end of each bending magnet to absorb the synchrotron radiation emitted by the beams. They operate at room temperature and

  2. Estimates of surface roughness derived from synthetic aperture radar (SAR) data

    NASA Technical Reports Server (NTRS)

    Evans, Diane L.; Farr, Tom G.; Van Zyl, Jakob J.

    1992-01-01

    Radar remote sensing data provide a unique perspective of the earth's crust and the processes that have influenced its evolution. Physically based models are required, however, to relate the geophysical quantities being measured by the radar sensor to useful geologic information. In this study, synthetic aperture radar (SAR) data over the Cima volcanic field in the Mojave Desert of California are quantitatively connected with microtopography through inversion of a radar backscatter model. Changes in surface roughness inferred from the derived microtopography are modeled and found to be consistent with aeolian mantling as surfaces age. Estimated rates of aeolian deposition for the Cima area are compared to the Lunar Crater volcanic field in Nevada. Rates of deposition appear to be higher at Cima volcanic field, most likely because of its proximity to Soda Lake, the main source of the aeolian material.

  3. Radar target recognition system using 3D mathematical model

    Microsoft Academic Search

    Yosuke Nakano; Yoshihisa Hara; Jun Saito; Yoshio Inasawa

    1998-01-01

    A target recognition system is described using 3-D mathematical models which simulate radar images. The simulated radar images are created from radar cross section (RCS) responses of the 3-D models and compared with measured target radar images. The 3-D models consist of several thousands facets, and one facet size is less than the radar resolution. An RCS response of each

  4. Capabilities of radar as they might relate to entomological studies

    NASA Technical Reports Server (NTRS)

    Skolnik, M. I.

    1979-01-01

    A tutoral background of radar capabilities and its potential for insect research is provided. The basic principles and concepts of radar were reviewed. Information on current radar equipment was examined. Specific issues related to insect research included; target cross-section, radar frequency, tracking target recognition and false alarms, clutter reduction, radar transmitter power, and ascertained atmospheric processes.

  5. Preparation of active absorbent for dry-type flue gas desulfurization from calcium oxide, coal fly ash, and gypsum

    Microsoft Academic Search

    Tomohiro Ishizuka; Hiroaki Tsuchiai; Takeshi Murayama; Tsunehiro Tanaka; Hideshi Hattori

    2000-01-01

    As compared to a commercial absorbent prepared from Ca(OH)â, gypsum (CaSOâ) and coal fly ash, an absorbent prepared by use of CaO in place of Ca(OH)â, exhibited a higher activity for dry-type flue gas desulfurization. The order of the addition of the raw materials in the slaking procedure has an effect on the activity of the resulting absorbent. The activity

  6. Comparison of TRMM Precipitation Radar and Airborne Radar Data.

    NASA Astrophysics Data System (ADS)

    Durden, S. L.; Im, E.; Haddad, Z. S.; Li, L.

    2003-06-01

    The first spaceborne weather radar is the precipitation radar (PR) on the Tropical Rainfall Measuring Mission (TRMM), which was launched in 1997. As part of the TRMM calibration and validation effort, an airborne rain-mapping radar (ARMAR) was used to make underflights of TRMM during the B portion of the Texas and Florida Underflights (TEFLUN-B) and the third Convection and Moisture Experiment (CAMEX-3) in 1998 and the Kwajalein Experiment (KWAJEX) in 1999. The TRMM PR and ARMAR both operate at 14 GHz, and both instruments use a downward-looking, cross-track scanning geometry, which allows direct comparison of data. Nearly simultaneous PR and ARMAR data were acquired in seven separate cases. These data are compared to examine the effects of larger resolution volume and lower sensitivity in the PR data relative to ARMAR. The PR and ARMAR data show similar structures, although the PR data tend to have lower maximum reflectivities and path attenuations because of nonuniform beam-filling effects. Nonuniform beam filling can also cause a bias in the observed path attenuation relative to that corresponding to the beam-averaged rain rate. The PR rain-type classification is usually consistent with the ARMAR data.

  7. Radar penetrates only the youngest geological units on Mars

    NASA Astrophysics Data System (ADS)

    Stillman, David E.; Grimm, Robert E.

    2011-03-01

    Signals from the Shallow Radar were intended to penetrate hundreds of meters or more into Mars, but subsurface reflections are abundant only in known or inferred ice-rich units and young (middle to late Amazonian), apparently pristine, volcanic units. As volcanic units age, fewer subsurface reflections are detected. Also, no subsurface reflections are detected from any northern hemisphere units inferred to be altered by water. We suggest that the general lack of subsurface reflections on Mars is not likely an indication that the shallow interior is devoid of structure and stratigraphy but rather an indication that dielectric contrasts cannot be detected due to signal attenuation originating from scattering and/or absorption. We constrained the attenuation rate in regions with no subsurface reflections to 0.065-0.27 dB/m. This corresponds to scattering losses from meter-scale fractures and/or lithologic density variations of 0.27-1.03 g/cm3. Alternatively, our laboratory measurements have shown that three monolayers of adsorbed water on 2.2-14 vol % smectite clays can completely absorb radar energy and would be equivalent to a global water layer just ˜0.2-0.6 m thick. We suggest that the increased attenuation in volcanic units comes from an increase in fracture density. Attenuation in water-altered units may be due to the greater heterogeneity in sedimentary units and/or chemical alteration that has formed high-surface-area smectites capable of holding the necessary amount of adsorbed water. Overall, the lack of widespread, deep subsurface reflections is due to the more Earth-like radar properties of Mars, as compared to the Moon-like properties that were anticipated.

  8. DIGITAL VISION he advent of phased array radars and space-time adaptive processing has given radar

    E-print Network

    Nehorai, Arye

    © DIGITAL VISION T he advent of phased array radars and space-time adaptive processing has given radar designers the ability make radars adaptable on receive. The current state of radar technolo- gy of pairs of complementary sequences. Shortly thereafter, Welti proposed to use Golay sequences in radar

  9. Broadband Polarization-Independent Perfect Absorber Using a Phase-Change Metamaterial at Visible Frequencies

    NASA Astrophysics Data System (ADS)

    Cao, Tun; Wei, Chen-Wei; Simpson, Robert E.; Zhang, Lei; Cryan, Martin J.

    2014-02-01

    We report a broadband polarization-independent perfect absorber with wide-angle near unity absorbance in the visible regime. Our structure is composed of an array of thin Au squares separated from a continuous Au film by a phase change material (Ge2Sb2Te5) layer. It shows that the near perfect absorbance is flat and broad over a wide-angle incidence up to 80° for either transverse electric or magnetic polarization due to a high imaginary part of the dielectric permittivity of Ge2Sb2Te5. The electric field, magnetic field and current distributions in the absorber are investigated to explain the physical origin of the absorbance. Moreover, we carried out numerical simulations to investigate the temporal variation of temperature in the Ge2Sb2Te5 layer and to show that the temperature of amorphous Ge2Sb2Te5 can be raised from room temperature to > 433 K (amorphous-to-crystalline phase transition temperature) in just 0.37 ns with a low light intensity of 95 nW/?m2, owing to the enhanced broadband light absorbance through strong plasmonic resonances in the absorber. The proposed phase-change metamaterial provides a simple way to realize a broadband perfect absorber in the visible and near-infrared (NIR) regions and is important for a number of applications including thermally controlled photonic devices, solar energy conversion and optical data storage.

  10. Simulation of a weather radar display for over-water airborne radar approaches

    NASA Technical Reports Server (NTRS)

    Clary, G. R.

    1983-01-01

    Airborne radar approach (ARA) concepts are being investigated as a part of NASA's Rotorcraft All-Weather Operations Research Program on advanced guidance and navigation methods. This research is being conducted using both piloted simulations and flight test evaluations. For the piloted simulations, a mathematical model of the airborne radar was developed for over-water ARAs to offshore platforms. This simulated flight scenario requires radar simulation of point targets, such as oil rigs and ships, distributed sea clutter, and transponder beacon replies. Radar theory, weather radar characteristics, and empirical data derived from in-flight radar photographs are combined to model a civil weather/mapping radar typical of those used in offshore rotorcraft operations. The resulting radar simulation is realistic and provides the needed simulation capability for ongoing ARA research.

  11. The instrumental principles of MST radars and incoherent scatter radars and the configuration of radar system hardware

    NASA Technical Reports Server (NTRS)

    Roettger, Juergen

    1989-01-01

    The principle of pulse modulation used in the case of coherent scatter radars (MST radars) is discussed. Coherent detection and the corresponding system configuration is delineated. Antenna requirements and design are outlined and the phase-coherent transmitter/receiver system is described. Transmit/receive duplexers, transmitters, receivers, and quadrature detectors are explained. The radar controller, integrator, decoder and correlator design as well as the data transfer and the control and monitoring by the host computer are delineated. Typical operation parameters of some well-known radars are summarized.

  12. Application of advanced methods for durability assessment of new absorber coatings

    SciTech Connect

    Frei, U.; Brunold, S. [Inst. of Technology, Rapperswil (Switzerland). Solarenergie Pruef- und Forschungsstelle; Koehl, M.; Brucker, F. [Fraunhofer Inst. fuer Solare Energiesysteme, Freiburg (Germany); Carlsson, B.; Moeller, K. [Swedish National Testing and Research Inst., Boraas (Sweden)

    1995-12-31

    Accelerated Life Testing of Solar Energy Materials has been one of the main topics within the former Task X, Solar Materials Research and Development, of the International Energy Agency (IEA) Solar Heating and Cooling Programme. In the case study of some selective solar absorber coating materials for domestic hot water systems procedures are presented for service time assessment, applicable for example to absorber coating materials. As a continuation of the finalized Task X a working group, Materials in Solar Thermal Systems, also in the framework of the International Energy Agency (IEA) Solar Heating and Cooling Programme was initiated. One of the first projects is described here. Its aim is to investigate the conformity of the durability assessment, applied on solar absorber coatings tested by different laboratories. Each lab is working independently, this means there is no information exchange between the labs until the results are on paper. Test samples are delivered by the participants. Four different absorber coatings are identified to be useful for the project. The coating materials as well as the production procedures of the coatings are not relevant for the study, therefore no information is given. The experimental procedures as well as the judgment over the different absorber coatings are described in detail. Some comparisons between individual results of the different labs indicates possible weaknesses and further necessary refinements.

  13. Two terminal micropower radar sensor

    DOEpatents

    McEwan, Thomas E. (Livermore, CA)

    1995-01-01

    A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground.

  14. Radar observations of Comet Halley

    NASA Technical Reports Server (NTRS)

    Campbell, D. B.; Harmon, J. K.; Shapiro, I. I.

    1989-01-01

    Five nights of Arecibo radar observations of Comet Halley are reported which reveal a feature in the overall average spectrum which, though weak, seems consistent with being an echo from the comet. The large radar cross section and large bandwidth of the feature suggest that the echo is predominantly from large grains which have been ejected from the nucleus. Extrapolation of the dust particle size distribution to large grain sizes gives a sufficient number of grains to account for the echo. The lack of a detectable echo from the nucleus, combined with estimates of its size and rotation rate from spacecraft encounters and other data, indicate that the nucleus has a surface of relatively high porosity.

  15. Goldstone Solar System Radar (GSSR)

    NASA Technical Reports Server (NTRS)

    Renzetti, N. A.

    1991-01-01

    The primary objective of the Goldstone Solar System Radar is the investigation of solar system bodies by means of Earth-based radar. Targets of primary interest include the Galilean moons, Saturn's rings and moons, and Earth-approaching asteroids and comets. Planets are also of interest, particularly Mercury and the planets to which NASA has not yet planned spacecraft visits. Based on a history of solid achievement, including the definition of the Astronomical Unit, imaging and topography of Mars, Venus, and Mercury, and contributions to the general theory of relativity, the program will continue to support flight project requirements and its primary objectives. The individual target objectives are presented, and information on the following topics are presented in tabular form: Deep Space Network support, compatibility tests, telemetry, command, and tracking support responsibility.

  16. Radar waveform diversity for tracking

    NASA Astrophysics Data System (ADS)

    Grishin, Yury

    2009-06-01

    The paper presents a brief survey of the main approaches for solving the problem of radar waveform selection for optimal tracking. The traditional approach to the system design has been to treat the detection and tracking subsystems as completely separate entities. In last years some new types of radars equipped with highly agile software driven waveform generators have appeared. This makes it possible to change the transmitted waveform at each time step for obtaining minimal tracking errors. Thus the problem of the waveform selection can be formulated as the optimisation problem of the following form: for given class of signals and target movement model to find the tracking filter structure and waveform parameter sequence which result in a minimum variance estimate of the target state vector. Two main approaches to waveform optimising have been considered in the paper: the control theoretic approach and information theoretic approach. The relationships between sensor characteristics and tracking algorithm are discussed.

  17. Radar altimeter data quality flagging

    NASA Astrophysics Data System (ADS)

    Laxon, S. W.; Rapley, C. G.

    The Seasat radar altimeter was designed to provide precise and accurate surface height measurements over the ocean. These data have been used in studies of the ocean geoid, tides, and currents. Several factors can affect the quality of the height measurements produced by the on-board processor. In particular, radar returns with time profiles which depart from a standard form can introduce significant errors. These arise over very calm seas, over rain cells or when sea ice or land are present within the altimeter footprint. Blunder point algorithms are used in the ground processing to flag outlying data points, but these fail to identify some of the anomalies that are observed. An alternative method for flagging poor quality data using a simple algorithm based on pulse shape is presented. It is demonstrated that the algorithm provides a sensitive means of editing altimeter ocean data. Furthermore, changes in surface type, such as transitions between open water and sea ice can be accurately located.

  18. Two terminal micropower radar sensor

    DOEpatents

    McEwan, T.E.

    1995-11-07

    A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground. 3 figs.

  19. The Arecibo Observatory as an MST radar

    NASA Technical Reports Server (NTRS)

    Woodman, R. F.

    1983-01-01

    The radars and other systems at the Arecibo Observatory were designed and built, originally, for incoherent-scatter and radio-astronomy research. More recently, important additions have been made for planetary radar and artificial RF heating of the ionosphere. Although designed and built for a different application, these systems have shown to be very powerful tools for tropospheric, stratospheric and mesospheric research. The Observatory at present has two main radars: one at 430 and the other at 2380 MHz. In addition, 50-MHz MST radar work has been done using portable transmitters brought to the Observatory for this purpose. This capability will become permanent with the recent acquisition of a transmitter at this frequency. Furthermore, control and data processing systems have been developed to use the powerful HF transmitter and antennas of the HF-heating facility as an HF bistatic radar. A brief description of the four radars available at the Observatory is presented.

  20. Spaceborne Imaging Radar-C instrument

    NASA Technical Reports Server (NTRS)

    Huneycutt, Bryan L.

    1993-01-01

    The Spaceborne Imaging Radar-C is the next radar in the series of spaceborne radar experiments, which began with Seasat and continued with SIR-A and SIR-B. The SIR-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low earth orbit. It is a multiparameter imaging radar that will be flown during at least two different seasons. The instrument operates in the squint alignment mode, the extended aperture mode, the scansar mode, and the interferometry mode. The instrument uses engineering techniques such as beam nulling for echo tracking, pulse repetition frequency hopping for Doppler centroid tracking, generating the frequency step chirp for radar parameter flexibility, block floating-point quantizing for data rate compression, and elevation beamwidth broadening for increasing the swath illumination.