WorldWideScience

Sample records for aperture lightweight space

  1. Hybrid Electrostatic/Flextensional Mirror for Lightweight, Large-Aperture, and Cryogenic Space Telescopes

    Science.gov (United States)

    Patrick, Brian; Moore, James; Hackenberger, Wesley; Jiang, Xiaoning

    2013-01-01

    A lightweight, cryogenically capable, scalable, deformable mirror has been developed for space telescopes. This innovation makes use of polymer-based membrane mirror technology to enable large-aperture mirrors that can be easily launched and deployed. The key component of this innovation is a lightweight, large-stroke, cryogenic actuator array that combines the high degree of mirror figure control needed with a large actuator influence function. The latter aspect of the innovation allows membrane mirror figure correction with a relatively low actuator density, preserving the lightweight attributes of the system. The principal components of this technology are lightweight, low-profile, high-stroke, cryogenic-capable piezoelectric actuators based on PMN-PT (piezoelectric lead magnesium niobate-lead titanate) single-crystal configured in a flextensional actuator format; high-quality, low-thermal-expansion polymer membrane mirror materials developed by NeXolve; and electrostatic coupling between the membrane mirror and the piezoelectric actuator assembly to minimize problems such as actuator print-through.

  2. Last results of technological developments for ultra-lightweight, large aperture, deployable mirror for space telescopes

    Science.gov (United States)

    Gambicorti, Lisa; D'Amato, Francesco; Vettore, Christian; Duò, Fabrizio; Guercia, Alessio; Patauner, Christian; Biasi, Roberto; Lisi, Franco; Riccardi, Armando; Gallieni, Daniele; Lazzarini, Paolo; Tintori, Matteo; Zuccaro Marchi, Alessandro; Pereira do Carmo, Joao

    2017-11-01

    The aim of this work is to describe the latest results of new technological concepts for Large Aperture Telescopes Technology (LATT) using thin deployable lightweight active mirrors. This technology is developed under the European Space Agency (ESA) Technology Research Program and can be exploited in all the applications based on the use of primary mirrors of space telescopes with large aperture, segmented lightweight telescopes with wide Field of View (FOV) and low f/#, and LIDAR telescopes. The reference mission application is a potential future ESA mission, related to a space borne DIAL (Differential Absorption Lidar) instrument operating around 935.5 nm with the goal to measure water vapor profiles in atmosphere. An Optical BreadBoard (OBB) for LATT has been designed for investigating and testing two critical aspects of the technology: 1) control accuracy in the mirror surface shaping. 2) mirror survivability to launch. The aim is to evaluate the effective performances of the long stroke smart-actuators used for the mirror control and to demonstrate the effectiveness and the reliability of the electrostatic locking (EL) system to restraint the thin shell on the mirror backup structure during launch. The paper presents a comprehensive vision of the breadboard focusing on how the requirements have driven the design of the whole system and of the various subsystems. The manufacturing process of the thin shell is also presented.

  3. Technological developments for ultra-lightweight, large aperture, deployable mirror for space telescopes

    Science.gov (United States)

    Zuccaro Marchi, Alessandro; D'Amato, Francesco; Gallieni, Daniele; Biasi, Roberto; Molina, Marco; Duò, Fabrizio; Ruder, Nikolaus; Salinari, Piero; Lisi, Franco; Riccardi, Armando; Gambicorti, Lisa; Simonetti, Francesca; Pereira do Carmo, Joao Pedro N.

    2017-11-01

    The increasing interest on space telescopes for scientific applications leads to implement the manufacturing technology of the most critical element, i.e. the primary mirror: being more suitable a large aperture, it must be lightweight and deployable. The presented topic was originally addressed to a spaceborne DIAL (Differential Absorption LIDAR) mission operating at 935.5 nm for the measurement of water vapour profile in atmosphere, whose results were presented at ICSO 2006 and 2008. Aim of this paper is to present the latest developments on the main issues related to the fabrication of a breadboard, covering two project critical areas identified during the preliminary studies: the design and performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch via Electrostatic Locking (EL) between mirror and backplane. The described work is developed under the ESA/ESTEC contract No. 22321/09/NL/RA. The lightweight mirror is structured as a central sector surrounded by petals, all of them actively controlled to reach the specified shape after initial deployment and then maintained within specs for the entire mission duration. The presented study concerns: a) testing the Carbon Fiber Reinforced Plastic (CFRP) backplane manufacturing and EL techniques, with production of suitable specimens; b) actuator design optimisation; c) design of the deployment mechanism including a high precision latch; d) the fabrication of thin mirrors mock-ups to validate the fabrication procedure for the large shells. The current activity aims to the construction of an optical breadboard capable of demonstrating the achievement of all these coupled critical aspects: optical quality of the thin shell mirror surface, actuators performances and back-plane - EL subsystem functionality.

  4. Large aperture telescope technology: a design for an active lightweight multi-segmented fold-out space mirror

    Science.gov (United States)

    Thompson, S. J.; Doel, A. P.; Whalley, M.; Edeson, R.; Edeson, R.; Tosh, I.; Poyntz-Wright, O.; Atad-Ettedgui, E.; Montgomery, D.; Nawasra, J.

    2017-11-01

    Large aperture telescope technology (LATT) is a design study for a differential lidar (DIAL) system; the main investigation being into suitable methods, technologies and materials for a 4-metre diameter active mirror that can be stowed to fit into a typical launch vehicle (e.g. ROKOT launcher with 2.1-metre diameter cargo) and can self-deploy - in terms of both leaving the space vehicle and that the mirrors unfold and self-align to the correct optical form within the tolerances specified. The primary mirror requirements are: main wavelength of 935.5 nm, RMS corrected wavefront error of λ/6, optical surface roughness better than 5 nm, areal density of less than 16 kg/m2 and 1-2 mirror shape corrections per orbit. The primary mirror consists of 7 segments - a central hexagonal mirror and 6 square mirror petals which unfold to form the 4-meter diameter aperture. The focus of the UK LATT consortium for this European Space Agency (ESA) funded project is on using lightweighted aluminium or carbon-fibre-composite materials for the mirror substrate in preference to more traditional materials such as glass and ceramics; these materials have a high strength and stiffness to weight ratio, significantly reducing risk of damage due to launch forces and subsequent deployment in orbit. We present an overview of the design, which includes suitable actuators for wavefront correction, petal deployment mechanisms and lightweight mirror technologies. Preliminary testing results from manufactured lightweight mirror samples will also be summarised.

  5. Ultra-Lightweight Large Aperture Support Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Ultra-lightweight membranes may prove to be very attractive for large aperture systems, but their value will be fully realized only if they are mated with equally...

  6. Hybrid Electrostatic/Flextensional Deformable Membrane Mirror for Lightweight, Large Aperture and Cryogenic Space Telescopes, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes innovative hybrid electrostatic/flextensional membrane deformable mirror capable of large amplitude aberration correction for large...

  7. Lightweight Space Tug body structure

    International Nuclear Information System (INIS)

    Lager, J.R.

    1976-01-01

    Lightweight honeycomb sandwich construction using a wide variety of metal and fibrous composite faceskins was used in the design of a typical Space Tug skirt structure. Relatively low magnitude combined loading of axial compression and torsion resulted in designs using ultrathin faceskins, light-weight honeycomb cores, and thin faceskin/core adhesive bond layers. Two of the designs with metal faceskins (aluminum and titanium) and four with fibrous composite faceskins (using combinations of fiberglass, boron, and graphite) were evaluated through the fabrication and structural test of a series of small development panels. The two most promising concepts with aluminum and graphite/epoxy faceskins, were further evaluated through the fabrication and structural test of larger compression and shear panels. All panels tested exceeded design ultimate load levels, thereby, verifying the structural integrity of the selected designs. Projected skirt structural weights for the graphite/epoxy and aluminum concepts fall within original weight guidelines established for the Space Tug vehicle

  8. Cryogenic Piezo Actuators for Lightweight, Large Aperture, Deployable Membrane Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Single crystal piezoelectric actuators are proposed to enable large stroke, high precision, shape control for cryogenic lightweight deployable membrane mirror...

  9. Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Future astrophysics missions will require lightweight, thermally stable, submillimeter reflectors in sizes of 4m and greater. To date, graphite fiber reinforced...

  10. Precision Membrane Optical Shell (PMOS) Technology for Lightweight LIDAR Apertures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision membrane optical shell (PMOS) technology is an innovative combination of 1) ultra lightweight optically smooth membrane thin films, 2) advanced mold based...

  11. Advanced lightweight optics development for space applications

    International Nuclear Information System (INIS)

    Bilbro, James W.

    1998-01-01

    A considerable amount of effort over the past year has been devoted to exploring ultra-lightweight optics for two specific NASA programs, the Next Generation Space Telescope (NGST), and the High Throughput X-ray Spectrometer (HTXS). Experimental investigations have been undertaken in a variety of materials including glass, composites, nickel, beryllium, Carbon fiber reinforced Silicon Carbide (CSiC), Reaction Bonded Silicon Carbide, Chemical Vapor Deposited Silicon Carbide, and Silicon. Overall results of these investigations will be summarized, and specific details will be provided concerning the in-house development of ultra-lightweight nickel replication for both grazing incidence and normal incidence optics. This will include x-ray test results of the grazing incidence optic and cryogenic test results of the normal incidence optic. The status of two 1.5 meter diameter demonstration mirrors for NGST will also be presented. These two demonstrations are aimed at establishing the capability to manufacture and test mirrors that have an areal density of 15 kilograms per square meter. Efforts in thin membrane mirrors and Fresnel lenses will also be briefly discussed

  12. A High Resolution, Light-Weight, Synthetic Aperture Radar for UAV Application

    International Nuclear Information System (INIS)

    Doerry, A.W.; Hensley, W.H.; Stence, J.; Tsunoda, S.I.; Pace, F.; Walker, B.C.; Woodring, M.

    1999-06-01

    (U) Sandia National Laboratories in collaboration with General Atomics (GA) has designed and built a high resolution, light-weight, Ku-band Synthetic Aperture Radar (SAR) known as ''Lynx''. Although Lynx can be operated on a wide variety of manned and unmanned platforms, its design is optimized for use on medium altitude Unmanned Aerial Vehicles (UAVS). In particular, it can be operated on the Predator, I-GNAT, and Prowler II platforms manufactured by GA. (U) The radar production weight is less than 120 lb and operates within a 3 GHz band from 15.2 GHz to 18.2 GHz with a peak output power of 320 W. Operating range is resolution and mode dependent but can exceed 45 km in adverse weather (4 mm/hr rain). Lynx has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in strip map mode, over substantial depression angles (5 to 60 deg) and squint angles (broadside and ±45 deg). Real-time Motion Compensation is implemented to allow high-quality image formation even during vehicle turns and other maneuvers

  13. New technologies for the actuation and controls of large aperture lightweight quality mirrors

    Science.gov (United States)

    Lih, S. S.; Yang, E. H.; Gullapalli, S. N.; Flood, R.

    2003-01-01

    This paper presents a set of candidate components: MEMS based large stroke (>100 microns) ultra lightweight (0.01 gm) discrete inch worm actuator technology, and a distributed actuator technology, in the context of a novel lightweight active flexure-hinged substrate concept that uses the nanolaminate face sheet.

  14. Apertures

    CERN Document Server

    Hansen, R C

    2014-01-01

    Microwave Scanning Antennas, Volume I: Apertures is a comprehensive account of phased arrays, multiple beam arrays, time domain and synthetic apertures, and adaptive antennas. Advances in continuous apertures and near field theory are discussed. Low noise and monopulse apertures, optical scanners, and large radomes are also covered, along with radio astronomy instruments and associated theory.Comprised of five chapters, this volume begins with an overview of aperture theory as well as aperture distributions and near field theory. The second and third chapters deal with mechanically steered and

  15. Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structures Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance and high impact resistance are desirable to...

  16. Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structures Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance, EMI shielding, and high impact resistance are...

  17. Lightweight High Efficiency Electric Motors for Space Applications

    Science.gov (United States)

    Robertson, Glen A.; Tyler, Tony R.; Piper, P. J.

    2011-01-01

    Lightweight high efficiency electric motors are needed across a wide range of space applications from - thrust vector actuator control for launch and flight applications to - general vehicle, base camp habitat and experiment control for various mechanisms to - robotics for various stationary and mobile space exploration missions. QM Power?s Parallel Path Magnetic Technology Motors have slowly proven themselves to be a leading motor technology in this area; winning a NASA Phase II for "Lightweight High Efficiency Electric Motors and Actuators for Low Temperature Mobility and Robotics Applications" a US Army Phase II SBIR for "Improved Robot Actuator Motors for Medical Applications", an NSF Phase II SBIR for "Novel Low-Cost Electric Motors for Variable Speed Applications" and a DOE SBIR Phase I for "High Efficiency Commercial Refrigeration Motors" Parallel Path Magnetic Technology obtains the benefits of using permanent magnets while minimizing the historical trade-offs/limitations found in conventional permanent magnet designs. The resulting devices are smaller, lower weight, lower cost and have higher efficiency than competitive permanent magnet and non-permanent magnet designs. QM Power?s motors have been extensively tested and successfully validated by multiple commercial and aerospace customers and partners as Boeing Research and Technology. Prototypes have been made between 0.1 and 10 HP. They are also in the process of scaling motors to over 100kW with their development partners. In this paper, Parallel Path Magnetic Technology Motors will be discussed; specifically addressing their higher efficiency, higher power density, lighter weight, smaller physical size, higher low end torque, wider power zone, cooler temperatures, and greater reliability with lower cost and significant environment benefit for the same peak output power compared to typically motors. A further discussion on the inherent redundancy of these motors for space applications will be provided.

  18. A future large-aperture UVOIR space observatory: reference designs

    Science.gov (United States)

    Rioux, Norman; Thronson, Harley; Feinberg, Lee; Stahl, H. Philip; Redding, Dave; Jones, Andrew; Sturm, James; Collins, Christine; Liu, Alice

    2015-09-01

    Our joint NASA GSFC/JPL/MSFC/STScI study team has used community-provided science goals to derive mission needs, requirements, and candidate mission architectures for a future large-aperture, non-cryogenic UVOIR space observatory. We describe the feasibility assessment of system thermal and dynamic stability for supporting coronagraphy. The observatory is in a Sun-Earth L2 orbit providing a stable thermal environment and excellent field of regard. Reference designs include a 36-segment 9.2 m aperture telescope that stows within a five meter diameter launch vehicle fairing. Performance needs developed under the study are traceable to a variety of reference designs including options for a monolithic primary mirror.

  19. Flextensional Microactuators for Large-Aperture Lightweight Cryogenic Deformable Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes large stroke and high precision single crystal flextensional piezoelectric microactuators for cryogenic optic devices such as large...

  20. Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Phase II effort will be an affordable demonstrated full-scale design for a thermally stable multi-meter submillimeter reflector. The Phase I...

  1. Precision Membrane Optical Shell (PMOS) Technology for RF/Microwave to Lightweight LIDAR Apertures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Membrane Optical Shell Technology (MOST) is an innovative combination of 1) very low areal density (40 to 200g/m2) optically smooth (<20 nm rms), metallic coated...

  2. Lightweight Radiator for in Space Nuclear Electric Propulsion

    Science.gov (United States)

    Craven, Paul; Tomboulian, Briana; SanSoucie, Michael

    2014-01-01

    Nuclear electric propulsion (NEP) is a promising option for high-speed in-space travel due to the high energy density of nuclear fission power sources and efficient electric thrusters. Advanced power conversion technologies may require high operating temperatures and would benefit from lightweight radiator materials. Radiator performance dictates power output for nuclear electric propulsion systems. Game-changing propulsion systems are often enabled by novel designs using advanced materials. Pitch-based carbon fiber materials have the potential to offer significant improvements in operating temperature, thermal conductivity, and mass. These properties combine to allow advances in operational efficiency and high temperature feasibility. An effort at the NASA Marshall Space Flight Center to show that woven high thermal conductivity carbon fiber mats can be used to replace standard metal and composite radiator fins to dissipate waste heat from NEP systems is ongoing. The goals of this effort are to demonstrate a proof of concept, to show that a significant improvement of specific power (power/mass) can be achieved, and to develop a thermal model with predictive capabilities making use of constrained input parameter space. A description of this effort is presented.

  3. NIAC Phase I Study Final Report on Large Ultra-Lightweight Photonic Muscle Space Structures

    Science.gov (United States)

    Ritter, Joe

    2016-01-01

    way to make large inexpensive deployable mirrors where the cost is measured in millions, not billions like current efforts. For example we seek an interim goal within 10 years of a Hubble size (2.4m) primary mirror weighing 1 pound at a cost of 10K in materials. Described here is a technology using thin ultra lightweight materials where shape can be controlled simply with a beam of light, allowing imaging with incredibly low mass yet precisely shaped mirrors. These " Photonic Muscle" substrates will eventually make precision control of giant s p a c e apertures (mirrors) possible. OCCAM substrates make precision control of giant ultra light-weight mirror apertures possible. This technology is posed to create a revolution in remote sensing by making large ultra lightweight space telescopes a fiscal and material reality over the next decade.

  4. Lightweight Metal Rubber Wire and Cable for Space Power Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA STTR program is to produce ultra-lightweight electrical wire and cable harnesses to reduce the liftoff weight of future space flight...

  5. Ultra-Lightweight High Efficiency Nanostructured Materials and Coatings for Deep Space Mission Environments, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic has developed a nanostructured spray self-assembly manufacturing method that has resulted in ultra-lightweight ( 1000%), and multi-layer, high efficiency...

  6. Innovative, Lightweight Thoraeus RubberTM for MMOD and Space Radiation Shielding, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic offers an innovative manufacturing process to yield ultra-lightweight radiation shielding nanocomposites by exploiting the concept of the Thoraeus filter...

  7. Multi-aperture digital coherent combining for free-space optical communication receivers.

    Science.gov (United States)

    Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

    2016-06-13

    Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

  8. Exo-planet Direct Imaging with On-Axis and/or Segmented Apertures in Space: Adaptive Compensation of Aperture Discontinuities

    Science.gov (United States)

    Soummer, Remi

    Capitalizing on a recent breakthrough in wavefront control theory for obscured apertures made by our group, we propose to demonstrate a method to achieve high contrast exoplanet imaging with on-axis obscured apertures. Our new algorithm, which we named Adaptive Compensation of Aperture Discontinuities (ACAD), provides the ability to compensate for aperture discontinuities (segment gaps and/or secondary mirror supports) by controlling deformable mirrors in a nonlinear wavefront control regime not utilized before but conceptually similar to the beam reshaping used in PIAA coronagraphy. We propose here an in-air demonstration at 1E- 7 contrast, enabled by adding a second deformable mirror to our current test-bed. This expansion of the scope of our current efforts in exoplanet imaging technologies will enabling us to demonstrate an integrated solution for wavefront control and starlight suppression on complex aperture geometries. It is directly applicable at scales from moderate-cost exoplanet probe missions to the 2.4 m AFTA telescopes to future flagship UVOIR observatories with apertures potentially 16-20 m. Searching for nearby habitable worlds with direct imaging is one of the top scientific priorities established by the Astro2010 Decadal Survey. Achieving this ambitious goal will require 1e-10 contrast on a telescope large enough to provide angular resolution and sensitivity to planets around a significant sample of nearby stars. Such a mission must of course also be realized at an achievable cost. Lightweight segmented mirror technology allows larger diameter optics to fit in any given launch vehicle as compared to monolithic mirrors, and lowers total life-cycle costs from construction through integration & test, making it a compelling option for future large space telescopes. At smaller scales, on-axis designs with secondary obscurations and supports are less challenging to fabricate and thus more affordable than the off-axis unobscured primary mirror designs

  9. Performance of Scattering Matrix Decomposition and Color Spaces for Synthetic Aperture Radar Imagery

    Science.gov (United States)

    2010-03-01

    Color Spaces and Synthetic Aperture Radar (SAR) Multicolor Imaging. 15 2.3.1 Colorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.3.2...III. Decomposition Techniques on SAR Polarimetry and Colorimetry applied to SAR Imagery...space polarimetric SAR systems. Colorimetry is also introduced in this chapter, presenting the fundamentals of the RGB and CMY color spaces, defined for

  10. Daris, a low-frequency distributed aperture array for radio astronomy in space

    NARCIS (Netherlands)

    Boonstra, A.J.; Saks, N.; Bentum, Marinus Jan; van 't Klooster, K.; Falcke, H.

    2010-01-01

    DARIS (Distributed Aperture Array for Radio Astronomy in Space) is a radio astronomy space mission concept aimed at observing the low-frequency radio sky in the range 1-10 MHz. Because of the Earth's ionospheric disturbances and opaqueness, this frequency range can only be observed from space. The

  11. Lightweight CNT Shielded Cables for Space Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The effects of electromagnetic interactions in electrical systems are of growing concern due to the increasing susceptibility of system components to electromagnetic...

  12. Scale-dependent Patterns in One-dimensional Fracture Spacing and Aperture Data

    Science.gov (United States)

    Roy, A.; Perfect, E.

    2013-12-01

    One-dimensional scanline data about fracture spacing and size attributes such as aperture or length are mostly considered in separate studies that compute the cumulative frequency of these attributes without regard to their actual spatial sequence. In a previous study, we showed that spacing data can be analyzed using lacunarity to identify whether fractures occur in clusters. However, to determine if such clusters also contain the largest fractures in terms of a size attribute such as aperture, it is imperative that data about the size attribute be integrated with information about fracture spacing. While for example, some researchers have considered aperture in conjunction with spacing, their analyses were either applicable only to a specific type of data (e.g. multifractal) or failed to characterize the data at different scales. Lacunarity is a technique for analyzing multi-scale non-binary data and is ideally-suited for characterizing scanline data with spacing and aperture values. We present a technique that can statistically delineate the relationship between size attributes and spatial clustering. We begin by building a model scanline that has complete partitioning of fractures with small and large apertures between the intercluster regions and clusters. We demonstrate that the ratio of lacunarity for this model to that of its counterpart for a completely randomized sequence of apertures can be used to determine whether large-aperture fractures preferentially occur next to each other. The technique is then applied to two natural fracture scanline datasets, one with most of the large apertures occurring in fracture clusters, and the other with more randomly-spaced fractures, without any specific ordering of aperture values. The lacunarity ratio clearly discriminates between these two datasets and, in the case of the first example, it is also able to identify the range of scales over which the widest fractures are clustered. The technique thus developed for

  13. Lightweight power bus for a baseload nuclear reactor in space

    International Nuclear Information System (INIS)

    Oberly, C.E.; Massie, L.D.; Hoffman, D.J.

    1989-01-01

    Space environmental interactions with the power distribution/power processing subsystem can become a serious problem for power systems rated at 10's to 100's of kilowatts. Utilization of ceramic superconductors at 1000 A/cm/sup 2/, which has already been demonstrated at 77 K in a conductor configuration may eliminate both bus mass and distribution voltage problems in a high power satellite. The analytical results presented here demonstrate that a superconducting coaxial power transmission bus offers significant benefits in reduced distribution voltage and mass

  14. Lightweight space radiator with leakage control by internal electrostatic fields

    International Nuclear Information System (INIS)

    Kim, H.; Bankoff, S.G.; Miksis, M.J.

    1991-01-01

    An electrostatic liquid film space radiator is proposed. This will employ an internal electrostatic field to prevent leakage of the liquid-metal coolant out of a puncture. This overcomes the major disadvantage of membrane radiators, which is their vulnerability to micrometeorite impacts. Calculations show that leaks of liquid lithium at 700 degree K can easily be stopped from punctures which are several mm in diameter, with very large safety factors. The basic idea lends itself to a variety of radiator concepts, both rotating and non-rotating. Some typical film thickness and pressure calculations in the presence of an electric field are shown

  15. Ultra High Temperature and Multifunctional Ceramic Matrix Composite – Coating Systems for Light-Weight Space and Aero Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — Revolutionary ultra-high temperature, high mechanical loading capable, oxidation resistant, durable ceramic coatings and light-weight fiber-reinforced Ceramic Matrix...

  16. An Engineering Design Reference Mission for a Future Large-Aperture UVOIR Space Observatory

    Science.gov (United States)

    Thronson, Harley A.; Bolcar, Matthew R.; Clampin, Mark; Crooke, Julie A.; Redding, David; Rioux, Norman; Stahl, H. Philip

    2016-01-01

    From the 2010 NRC Decadal Survey and the NASA Thirty-Year Roadmap, Enduring Quests, Daring Visions, to the recent AURA report, From Cosmic Birth to Living Earths, multiple community assessments have recommended development of a large-aperture UVOIR space observatory capable of achieving a broad range of compelling scientific goals. Of these priority science goals, the most technically challenging is the search for spectroscopic biomarkers in the atmospheres of exoplanets in the solar neighborhood. Here we present an engineering design reference mission (EDRM) for the Advanced Technology Large-Aperture Space Telescope (ATLAST), which was conceived from the start as capable of breakthrough science paired with an emphasis on cost control and cost effectiveness. An EDRM allows the engineering design trade space to be explored in depth to determine what are the most demanding requirements and where there are opportunities for margin against requirements. Our joint NASA GSFC/JPL/MSFC/STScI study team has used community-provided science goals to derive mission needs, requirements, and candidate mission architectures for a future large-aperture, non-cryogenic UVOIR space observatory. The ATLAST observatory is designed to operate at a Sun-Earth L2 orbit, which provides a stable thermal environment and excellent field of regard. Our reference designs have emphasized a serviceable 36-segment 9.2 m aperture telescope that stows within a five-meter diameter launch vehicle fairing. As part of our cost-management effort, this particular reference mission builds upon the engineering design for JWST. Moreover, it is scalable to a variety of launch vehicle fairings. Performance needs developed under the study are traceable to a variety of additional reference designs, including options for a monolithic primary mirror.

  17. CeSiCò - a new technology for lightweight and cost effective space instruments structures and mirrors

    Science.gov (United States)

    Devilliers, Christophe; Krödel, Matthias

    2017-11-01

    Alcatel Alenia Space and ECM have jointly developed a new ceramic material to produce lightweight, stiff, stable and cost effective structures and mirrors for space instrument the CesicÒ. Its intrinsic properties, added to ample manufacturing capabilities allow to manufacture stiff and lightweight cost effective mirrors and structure for space instruments. Different scale 1 flight representative CesicÒ optical structures have been manufactured and successfully tested under very strong dynamic environment and cryogenic condition down to 30K CesicÒ is also envisaged for large and lightweight space telescopes mirrors, a large CesicÒ 1 meter class mirror with an area mass of less than 25 Kg/m2 has been sized again launch loads and WFE performance and manufactured. CesicÒ applicability for large focal plane have been demonstrated through different scale 1 breadboards. Based on these successful results, AlcatelAleniaSpace and ECM are now in position to propose for space this technology with new innovative concepts thanks to the CesicÒ manufacturing capabilities. CesicÒ has therefore been selected for the structure and mirrors parts of a flight instrument payload and the manufacturing of the flight hardware is already underway. An high temperature high gain lightweight antenna breadboard is also under manufacturing for Bepi colombo mission. CesicÒ is therefore a good candidate for future challenging space instruments and is currently proposed for Japan and US space projects.

  18. Characterising rock fracture aperture-spacing relationships using power-law relationships: some considerations

    Science.gov (United States)

    Brook, Martin; Hebblewhite, Bruce; Mitra, Rudrajit

    2016-04-01

    The size-scaling of rock fractures is a well-studied problem in geology, especially for permeability quantification. The intensity of fractures may control the economic exploitation of fractured reservoirs because fracture intensity describes the abundance of fractures potentially available for fluid flow. Moreover, in geotechnical engineering, fractures are important for parameterisation of stress models and excavation design. As fracture data is often collected from widely-spaced boreholes where core recovery is often incomplete, accurate interpretation and representation of fracture aperture-frequency relationships from sparse datasets is important. Fracture intensity is the number of fractures encountered per unit length along a sample scanline oriented perpendicular to the fractures in a set. Cumulative frequency of fractures (F) is commonly related to fracture aperture (A) in the form of a power-law (F = aA-b), with variations in the size of the a coefficient between sites interpreted to equate to fracture frequency for a given aperture (A). However, a common flaw in this approach is that even a small change in b can have a large effect on the response of the fracture frequency (F) parameter. We compare fracture data from the Late Permian Rangal Coal Measures from Australia's Bowen Basin, with fracture data from Jurassic carbonates from the Sierra Madre Oriental, northeastern Mexico. Both power-law coefficient a and exponent b control the fracture aperture-frequency relationship in conjunction with each other; that is, power-laws with relatively low a coefficients have relatively high b exponents and vice versa. Hence, any comparison of different power-laws must take both a and b into consideration. The corollary is that different sedimentary beds in the Sierra Madre carbonates do not show ˜8× the fracture frequency for a given fracture aperture, as based solely on the comparison of coefficient a. Rather, power-law "sensitivity factors" developed from both

  19. Spacecraft Conceptual Design for the 8-Meter Advanced Technology Large Aperture Space Telescope (ATLAST)

    Science.gov (United States)

    Hopkins, Randall C.; Capizzo, Peter; Fincher, Sharon; Hornsby, Linda S.; Jones, David

    2010-01-01

    The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8-meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

  20. Nonlinear Analysis of the Space Shuttle Super-Lightweight External Fuel Tank

    Science.gov (United States)

    Nemeth, Michael P.; Britt, Vicki O.; Collins, Timothy J.; Starnes, James H., Jr.

    1996-01-01

    The results of buckling and nonlinear analyses of the Space Shuttle External Tank super-lightweight liquid oxygen (LOX) tank are presented. Modeling details and results are presented for two prelaunch loading conditions and for two full-scale structural tests conducted on the original external tank. These results illustrate three distinctly different types of nonlinear responses for thin-walled shells subjected to combined mechanical and thermal loads. These nonlinear response phenomena consist of bifurcation-type buckling, short-wavelength nonlinear bending, and nonlinear collapse associated with a limit point. For each case, the results show that accurate predictions of nonlinear behavior generally require a large scale high-fidelity finite element model. Results are also presented that show that a fluid filled launch vehicle shell can be highly sensitive to initial geometric imperfections. In addition, results presented for two full scale structural tests of the original standard weight external tank suggest that the finite element modeling approach used in the present study is sufficient for representing the nonlinear behavior of the super lightweight LOX tank.

  1. SpaceWire- Based Control System Architecture for the Lightweight Advanced Robotic Arm Demonstrator [LARAD

    Science.gov (United States)

    Rucinski, Marek; Coates, Adam; Montano, Giuseppe; Allouis, Elie; Jameux, David

    2015-09-01

    The Lightweight Advanced Robotic Arm Demonstrator (LARAD) is a state-of-the-art, two-meter long robotic arm for planetary surface exploration currently being developed by a UK consortium led by Airbus Defence and Space Ltd under contract to the UK Space Agency (CREST-2 programme). LARAD has a modular design, which allows for experimentation with different electronics and control software. The control system architecture includes the on-board computer, control software and firmware, and the communication infrastructure (e.g. data links, switches) connecting on-board computer(s), sensors, actuators and the end-effector. The purpose of the control system is to operate the arm according to pre-defined performance requirements, monitoring its behaviour in real-time and performing safing/recovery actions in case of faults. This paper reports on the results of a recent study about the feasibility of the development and integration of a novel control system architecture for LARAD fully based on the SpaceWire protocol. The current control system architecture is based on the combination of two communication protocols, Ethernet and CAN. The new SpaceWire-based control system will allow for improved monitoring and telecommanding performance thanks to higher communication data rate, allowing for the adoption of advanced control schemes, potentially based on multiple vision sensors, and for the handling of sophisticated end-effectors that require fine control, such as science payloads or robotic hands.

  2. Distress detection, location, and communications using advanced space technology. [satellite-borne synthetic aperture radar

    Science.gov (United States)

    Sivertson, W. E., Jr.

    1977-01-01

    This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

  3. Ergonomic Evaluation of Space Shuttle Light-Weight Seat Lever Position and Operation

    Science.gov (United States)

    Maida, J.; Rajulu, Sudhakar L.; Bond, Robert L. (Technical Monitor)

    2000-01-01

    During a Shuttle flight in the early part of 1999, one of the crewmembers was unable to operate the backrest lever for the light-weight seat in microgravity. It is essential that the crewmembers are able to adjust this back-rest lever, which is titled forward 2 degrees from vertical during launch and then moved backwards to 10 degrees aft of vertical upon reaching orbit. This adjustment is needed to cushion the crewmembers during an inadvertent crash landing situation. The original Shuttle seats, which had seat controls located on the front left and right sides of the seat, were replaced recently with the new light-weight seats. The controls for these new, seats were moved to the night side with one control at the front and the other at the back. While it was uncertain whether the problem encountered was unique to that crewmember or not it was clear to the personnel responsible for maintaining the Shuttle seats that not knowing the cause of the problem posed a safety concern for NASA. Hence the Anthropometry and Biomechanics Facility (ABF) of the Johnson Space Center was requested to perform an evaluation of the seat controls and provide NASA with appropriate recommendations on whether the seat lever positions and operations should be modified. The ABF designed an experiment to investigate the amount of pull force exerted by subjects, wearing an unpressurized or pressurized crew launch escape suit, when controls were placed in the front and back (on the right side) of the light-weight seat. Single-axis load cells were attached to the seat levers, which measured the maximum static pull forces that were exerted by the subjects. Twelve subjects, six male and six female, participated in this study. Each subject was asked to perform the pull test at least three times for each combination of lever position and suit pressure conditions. The results from this study showed that as a whole (or in general), the subjects were able to pull on the lever at the back position with

  4. Digital Beamforming Synthetic Aperture Radar Developments at NASA Goddard Space Flight Center

    Science.gov (United States)

    Rincon, Rafael; Fatoyinbo, Temilola; Osmanoglu, Batuhan; Lee, Seung Kuk; Du Toit, Cornelis F.; Perrine, Martin; Ranson, K. Jon; Sun, Guoqing; Deshpande, Manohar; Beck, Jaclyn; hide

    2016-01-01

    Advanced Digital Beamforming (DBF) Synthetic Aperture Radar (SAR) technology is an area of research and development pursued at the NASA Goddard Space Flight Center (GSFC). Advanced SAR architectures enhances radar performance and opens a new set of capabilities in radar remote sensing. DBSAR-2 and EcoSAR are two state-of-the-art radar systems recently developed and tested. These new instruments employ multiple input-multiple output (MIMO) architectures characterized by multi-mode operation, software defined waveform generation, digital beamforming, and configurable radar parameters. The instruments have been developed to support several disciplines in Earth and Planetary sciences. This paper describes the radars advanced features and report on the latest SAR processing and calibration efforts.

  5. Analysis of compound parabolic concentrators and aperture averaging to mitigate fading on free-space optical links

    Science.gov (United States)

    Wasiczko, Linda M.; Smolyaninov, Igor I.; Davis, Christopher C.

    2004-01-01

    Free space optics (FSO) is one solution to the bandwidth bottleneck resulting from increased demand for broadband access. It is well known that atmospheric turbulence distorts the wavefront of a laser beam propagating through the atmosphere. This research investigates methods of reducing the effects of intensity scintillation and beam wander on the performance of free space optical communication systems, by characterizing system enhancement using either aperture averaging techniques or nonimaging optics. Compound Parabolic Concentrators, nonimaging optics made famous by Winston and Welford, are inexpensive elements that may be easily integrated into intensity modulation-direct detection receivers to reduce fading caused by beam wander and spot breakup in the focal plane. Aperture averaging provides a methodology to show the improvement of a given receiver aperture diameter in averaging out the optical scintillations over the received wavefront.

  6. Calibration and performance measurements for the nasa deep space network aperture enhancement project (daep)

    Science.gov (United States)

    LaBelle, Remi C.; Rochblatt, David J.

    2018-06-01

    The NASA Deep Space Network (DSN) has recently constructed two new 34-m antennas at the Canberra Deep Space Communications Complex (CDSCC). These new antennas are part of the larger DAEP project to add six new 34-m antennas to the DSN, including two in Madrid, three in Canberra and one in Goldstone (California). The DAEP project included development and implementation of several new technologies for the X, and Ka (32 GHz) -band uplink and downlink electronics. The electronics upgrades were driven by several different considerations, including parts obsolescence, cost reduction, improved reliability and maintainability, and capability to meet future performance requirements. The new antennas are required to support TT&C links for all of the NASA deep-space spacecraft, as well as for several international partners. Some of these missions, such as Voyager 1 and 2, have very limited link budgets, which results in demanding requirements for system G/T performance. These antennas are also required to support radio science missions with several spacecraft, which dictate some demanding requirements for spectral purity, amplitude stability and phase stability for both the uplink and downlink electronics. After completion of these upgrades, a comprehensive campaign of tests and measurements took place to characterize the electronics and calibrate the antennas. Radiometric measurement techniques were applied to characterize, calibrate, and optimize the performance of the antenna parameters. These included optical and RF high-resolution holographic and total power radiometry techniques. The methodology and techniques utilized for the measurement and calibration of the antennas is described in this paper. Lessons learned (not all discussed in this paper) from the commissioning of the first antenna (DSS-35) were applied to the commissioning of the second antenna (DSS-36). These resulted in achieving antenna aperture efficiency of 66% (for DSS-36), at Ka-Band (32-Ghz), which is

  7. 8 Meter Advanced Technology Large-Aperture Space Telescope (ATLAST-8m)

    Science.gov (United States)

    Stahl, H. Philip

    2010-01-01

    ATLAST-8m (Advanced Technology Large Aperture Space Telescope) is a proposed 8-meter monolithic UV/optical/NIR space observatory (wavelength range 110 to 2500 nm) to be placed in orbit at Sun-Earth L2 by NASA's planned Ares V heavy lift vehicle. Given its very high angular resolution (15 mas @ 500 nm), sensitivity and performance stability, ATLAST-8m is capable of achieving breakthroughs in a broad range of astrophysics including: Is there life elsewhere in the Galaxy? An 8-meter UVOIR observatory has the performance required to detect habitability (H2O, atmospheric column density) and biosignatures (O2, O3, CH4) in terrestrial exoplanet atmospheres, to reveal the underlying physics that drives star formation, and to trace the complex interactions between dark matter, galaxies, and intergalactic medium. The ATLAST Astrophysics Strategic Mission Concept Study developed a detailed point design for an 8-m monolithic observatory including optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; mass and power budgets; and system cost. The results of which were submitted by invitation to NRC's 2010 Astronomy & Astrophysics Decadal Survey.

  8. Structural Feasibility Analysis of a Robotically Assembled Very Large Aperture Optical Space Telescope

    Science.gov (United States)

    Wilkie, William Keats; Williams, R. Brett; Agnes, Gregory S.; Wilcox, Brian H.

    2007-01-01

    This paper presents a feasibility study of robotically constructing a very large aperture optical space telescope on-orbit. Since the largest engineering challenges are likely to reside in the design and assembly of the 150-m diameter primary reflector, this preliminary study focuses on this component. The same technology developed for construction of the primary would then be readily used for the smaller optical structures (secondary, tertiary, etc.). A reasonable set of ground and on-orbit loading scenarios are compiled from the literature and used to define the structural performance requirements and size the primary reflector. A surface precision analysis shows that active adjustment of the primary structure is required in order to meet stringent optical surface requirements. Two potential actuation strategies are discussed along with potential actuation devices at the current state of the art. The finding of this research effort indicate that successful technology development combined with further analysis will likely enable such a telescope to be built in the future.

  9. A novel lightweight Fizeau infrared interferometric imaging system

    Science.gov (United States)

    Hope, Douglas A.; Hart, Michael; Warner, Steve; Durney, Oli; Romeo, Robert

    2016-05-01

    Aperture synthesis imaging techniques using an interferometer provide a means to achieve imagery with spatial resolution equivalent to a conventional filled aperture telescope at a significantly reduced size, weight and cost, an important implication for air- and space-borne persistent observing platforms. These concepts have been realized in SIRII (Space-based IR-imaging interferometer), a new light-weight, compact SWIR and MWIR imaging interferometer designed for space-based surveillance. The sensor design is configured as a six-element Fizeau interferometer; it is scalable, light-weight, and uses structural components and main optics made of carbon fiber replicated polymer (CFRP) that are easy to fabricate and inexpensive. A three-element prototype of the SIRII imager has been constructed. The optics, detectors, and interferometric signal processing principles draw on experience developed in ground-based astronomical applications designed to yield the highest sensitivity and resolution with cost-effective optical solutions. SIRII is being designed for technical intelligence from geo-stationary orbit. It has an instantaneous 6 x 6 mrad FOV and the ability to rapidly scan a 6x6 deg FOV, with a minimal SNR. The interferometric design can be scaled to larger equivalent filled aperture, while minimizing weight and costs when compared to a filled aperture telescope with equivalent resolution. This scalability in SIRII allows it address a range of IR-imaging scenarios.

  10. Results from a multi aperture Fizeau interferometer ground testbed: demonstrator for a future space-based interferometer

    Science.gov (United States)

    Baccichet, Nicola; Caillat, Amandine; Rakotonimbahy, Eddy; Dohlen, Kjetil; Savini, Giorgio; Marcos, Michel

    2016-08-01

    In the framework of the European FP7-FISICA (Far Infrared Space Interferometer Critical Assessment) program, we developed a miniaturized version of the hyper-telescope to demonstrate multi-aperture interferometry on ground. This setup would be ultimately integrated into a CubeSat platform, therefore providing the first real demonstrator of a multi aperture Fizeau interferometer in space. In this paper, we describe the optical design of the ground testbed and the data processing pipeline implemented to reconstruct the object image from interferometric data. As a scientific application, we measured the Sun diameter by fitting a limb-darkening model to our data. Finally, we present the design of a CubeSat platform carrying this miniature Fizeau interferometer, which could be used to monitor the Sun diameter over a long in-orbit period.

  11. Registered particles onboard identification in the various apertures of GAMMA-400 space gamma-telescope

    Science.gov (United States)

    Arkhangelskaja, Irene

    2016-07-01

    GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the gamma-telescope onboard international satellite gamma-observatory designed for particle registration in the wide energy band. Its parameters are optimized for detection of gamma-quanta with the energy ˜ 100 GeV in the main aperture. The main scientific goals of GAMMA-400 are to investigate fluxes of γ-rays and the electron-positron cosmic ray component possibly generated by dark matter particles decay or annihilation and to search for and study in detail discrete γ-ray sources, to investigate the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-emission from the active Sun. This article presents analysis of detected events identification procedures and energy resolution in three apertures provide particles registration both from upper and lateral directions based on GAMMA-400 modeling due special designed software. Time and segmentation methods are used to reject backsplash (backscattering particles created when high energy γ-rays interact with the calorimeter's matter and move in the opposite direction) in the main aperture while only energy deposition analysis allows to reject this effect in the additional and lateral ones. The main aperture provides the best angular (all strip layers information analysis) and energy (energy deposition in the all detectors studying) resolution in the energy range 0.1 - 3 × 10^{3} GeV. The energy resolution in this band is 1%. Triggers in the main aperture will be formed using information about particle direction provided by time of flight system and presence of charged particle or backsplash signal formed according to analysis of energy deposition in combination of all two-layers anticoincidence systems individual detectors. In the additional aperture gamma-telescope allows to register events in the energy band 10 × 10^{-3} - 3 × 10^{3} GeV. The additional aperture energy resolution provides due to

  12. Thermal Analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8 Meter Primary Mirror

    Science.gov (United States)

    Hornsby, Linda; Stahl, H. Philip; Hopkins, Randall C.

    2010-01-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The primary mirror will be maintained at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop(R) SINDA/FLUINT(R) was used for the thermal analysis and the radiation environment was analyzed using RADCAD(R). A XX node model was executed in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew or 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the environment which influences the thermal performance. All assumptions that were used in the analysis are also documented. Parametric analyses are summarized for design parameters including primary mirror coatings and sunshade configuration. Estimates of mirror heater power requirements are reported. The thermal model demonstrates results for the primary mirror heated from the back side and edges using a heater system with multiple independently controlled zones.

  13. Active galactic nucleus and quasar science with aperture masking interferometry on the James Webb Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Ford, K. E. Saavik; McKernan, Barry [Department of Science, Borough of Manhattan Community College, City University of New York, New York, NY 10007 (United States); Sivaramakrishnan, Anand; Martel, André R.; Koekemoer, Anton [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lafrenière, David [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, QC H3C 3J7 (Canada); Parmentier, Sébastien [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2014-03-10

    Due to feedback from accretion onto supermassive black holes (SMBHs), active galactic nuclei (AGNs) are believed to play a key role in ΛCDM cosmology and galaxy formation. However, AGNs extreme luminosities and the small angular size of their accretion flows create a challenging imaging problem. We show that the James Webb Space Telescope's Near Infrared Imager and Slitless Spectrograph (JWST-NIRISS) Aperture Masking Interferometry (AMI) mode will enable true imaging (i.e., without any requirement of prior assumptions on source geometry) at ∼65 mas angular resolution at the centers of AGNs. This is advantageous for studying complex extended accretion flows around SMBHs and in other areas of angular-resolution-limited astrophysics. By simulating data sequences incorporating expected sources of noise, we demonstrate that JWST-NIRISS AMI mode can map extended structure at a pixel-to-pixel contrast of ∼10{sup –2} around an L = 7.5 point source, using short exposure times (minutes). Such images will test models of AGN feedback, fueling, and structure (complementary with ALMA observations), and are not currently supported by any ground-based IR interferometer or telescope. Binary point source contrast with NIRISS is ∼10{sup –4} (for observing binary nuclei in merging galaxies), significantly better than current ground-based optical or IR interferometry. JWST-NIRISS's seven-hole non-redundant mask has a throughput of 15%, and utilizes NIRISS's F277W (2.77 μm), F380M (3.8 μm), F430M (4.3 μm), and F480M (4.8 μm) filters. NIRISS's square pixels are 65 mas per side, with a field of view ∼2' × 2'. We also extrapolate our results to AGN science enabled by non-redundant masking on future 2.4 m and 16 m space telescopes working at long-UV to near-IR wavelengths.

  14. Low cost realization of space-borne synthectic aperture radar - MicroSAR

    Science.gov (United States)

    Carter, D.; Hall, C.

    associated with implementing spaceborne SAR systems is an aspect of work that has been addressed over the past decade by the main S RA system expert companies. As the experimental systems have been realized and understood, so there has been a move to transfer these systems from the research and scientific domains into operational and commercial implementations. The end of the cold war, combined with the ever increasingly competitive telecommunications market, have assisted in driving down the launch costs, a significant cost element in any space system budget. To take maximum benefit from this it is still necessary to be able to make light weight satellites, in the region of 450 Kgs or less. Typically SAR satellites have been in the neighbourhood of 1.5 to 2.5 Tonnes. In order to achieve the low cost systems, not only the satellite mass needs to be tackled but also several other factors:- Design complexity- Production costs- Performance- Calibration and verification A novel approach has been established to address all of these factors. Developments are already in progress to prove the approach and that the low costs are achievable. This is called MicroSAR. This paper starts with an overview of the market status. A description of the MicroSAR system, its developments, calibration philosophy, trade-offs carried out, its performance envelope and an outline of the steps taken to achieve a low cost Synthetic Aperture Radar system are then presented.

  15. Development of technology for lightweight Beryllium Cassegrain Telescope for space applications and lessons learnt

    Science.gov (United States)

    Greger, R.; Rugi, E.; Hausner, Th.; Jahnen, W.; Frei, S.; Pellaton, D.; Mueller, P.; Hollenbach, I.

    2017-11-01

    This paper gives an overview on the development of a light weighted Cassegrain telescope with a 200 mm optical aperture as one key element of the Laser Altimeter which will fly on the BepiColombo mission to Mercury (BELA).The Receiver Telescope (RTL) collects the light pulse transmitted to Mercury and reflected from the planet's surface. Mercury's challenging thermal environment, the thermo-mechanical stability of the telescope and the stringent instrument's mass budget require the implementation of an innovative design solution to achieve the requested optical performance over an extended temperature range.

  16. Lightweight, High-Flow, Low Connection-Force, In-Space Cryogenic Propellant Coupling, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Three of the key abilities needed for making future NASA and commercial in-space transportation systems more affordable and capable are: a) the ability to 'live off...

  17. Lightweight, High-Flow, Low Connection-Force, In-Space Cryogenic Propellant Coupling, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Three of the key abilities needed for making future NASA and commercial launch and in-space transportation systems more affordable and capable are: a) the ability to...

  18. Near-Space TOPSAR Large-Scene Full-Aperture Imaging Scheme Based on Two-Step Processing

    Directory of Open Access Journals (Sweden)

    Qianghui Zhang

    2016-07-01

    Full Text Available Free of the constraints of orbit mechanisms, weather conditions and minimum antenna area, synthetic aperture radar (SAR equipped on near-space platform is more suitable for sustained large-scene imaging compared with the spaceborne and airborne counterparts. Terrain observation by progressive scans (TOPS, which is a novel wide-swath imaging mode and allows the beam of SAR to scan along the azimuth, can reduce the time of echo acquisition for large scene. Thus, near-space TOPS-mode SAR (NS-TOPSAR provides a new opportunity for sustained large-scene imaging. An efficient full-aperture imaging scheme for NS-TOPSAR is proposed in this paper. In this scheme, firstly, two-step processing (TSP is adopted to eliminate the Doppler aliasing of the echo. Then, the data is focused in two-dimensional frequency domain (FD based on Stolt interpolation. Finally, a modified TSP (MTSP is performed to remove the azimuth aliasing. Simulations are presented to demonstrate the validity of the proposed imaging scheme for near-space large-scene imaging application.

  19. Cryogenic explosion environment modeling and testing of space shuttle and light-weight radioisotope heater unit interactions

    International Nuclear Information System (INIS)

    Johnson, E.W.

    1985-10-01

    In order to assess the risk to the world's populace in the event of a Space Shuttle accident when radioisotope-containing heat sources are on board, testing of that system must be performed to determine release point, environments required, and the size distribution of the released fuel. To evaluate the performance of the Light-Weight Radioisotope Heater Unit (LWRHU) (101 of these 1-W items are placed on the Galileo spacecraft which will be launched from the Space Shuttle), some high-velocity impact and flyer plate testing was carried out. The results showed that a bare urania-fueled LWRHU clad (approximately 1-mm thick platinum-30 wt % rhodium alloy) will withstand 1100 m/s flyer plate (3.5-mm thick aluminum) impacts and 330 m/s impacts upon the Space Shuttle floor (approximately 12-mm thick aluminum) without rupture or fuel release. Velocities in the order of 600 m/s on a steel surface will cause clad failure with fuel release. The fuel breakup patterns were characterized as to quantity in a specific size range. These data were employed in the formal Safety Analysis Report for the LWRHU to support the planned 1986 Galileo launch. 19 figs

  20. Programmable Ultra Lightweight System Adaptable Radio (PULSAR) Low Cost Telemetry - Access from Space Advanced Technologies or Down the Middle

    Science.gov (United States)

    Sims. Herb; Varnavas, Kosta; Eberly, Eric

    2013-01-01

    Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 1990's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast, presently qualified satellite transponder applications were developed during the early 1960's space program. Programmable Ultra Lightweight System Adaptable Radio (PULSAR, NASA-MSFC SDR) technology revolutionizes satellite transponder technology by increasing data through-put capability by, at least, an order of magnitude. PULSAR leverages existing Marshall Space Flight Center SDR designs and commercially enhanced capabilities to provide a path to a radiation tolerant SDR transponder. These innovations will (1) reduce the cost of NASA Low Earth Orbit (LEO) and Deep Space transponders, (2) decrease power requirements, and (3) a commensurate volume reduction. Also, PULSAR increases flexibility to implement multiple transponder types by utilizing the same hardware with altered logic - no analog hardware change is required - all of which can be accomplished in orbit. This provides high capability, low cost, transponders to programs of all sizes. The final project outcome would be the introduction of a Technology Readiness Level (TRL) 7 low-cost CubeSat to SmallSat telemetry system into the NASA Portfolio.

  1. Lightweight, Radiation Resistant, Low Tg, Thoraeus Rubber Inflatable Space Habitats, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic's Shape Memory Metal RubberTM (SM-MR) exhibits reconfigurable and recoverable changes in structural and RF properties as it can be mechanically and...

  2. Super Lightweight, Metal Rubber Fabric for Extreme Space Environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic has fabricated revolutionary nanostructured, yet macroscale, multifunctional Metal RubberTM films via layer-by-layer, molecular self-assembly, which...

  3. Light-weight Self-correcting Inflatable/rigidizable Space Antennas, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA/L'Garde Inflatable Antenna Experiment (IAE)flown in STS-77 has showed the potential of this class of structures in significantly reducing the costs for...

  4. Space robotics--DLR's telerobotic concepts, lightweight arms and articulated hands.

    Science.gov (United States)

    Hirzinger, G; Brunner, B; Landzettel, K; Sporer, N; Butterfass, J; Schedl, M

    2003-01-01

    The paper briefly outlines DLR's experience with real space robot missions (ROTEX and ETS VII). It then discusses forthcoming projects, e.g., free-flying systems in low or geostationary orbit and robot systems around the space station ISS, where the telerobotic system MARCO might represent a common baseline. Finally it describes our efforts in developing a new generation of "mechatronic" ultra-light weight arms with multifingered hands. The third arm generation is operable now (approaching present-day technical limits). In a similar way DLR's four-fingered hand II was a big step towards higher reliability and yet better performance. Artificial robonauts for space are a central goal now for the Europeans as well as for NASA, and the first verification tests of DLR's joint components are supposed to fly already end of 93 on the space station.

  5. OCCAMS: Optically Controlled and Corrected Active Meta-material Space Structures (Ultra-Lightweight Photonic Muscle Space Structures Phase II)

    Data.gov (United States)

    National Aeronautics and Space Administration — Photons weigh nothing. Why must even small space telescopes have high mass? Our team has demonstrated this is not the case using a completely novel approach to...

  6. A high-order integral solver for scalar problems of diffraction by screens and apertures in three-dimensional space

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Oscar P., E-mail: obruno@caltech.edu; Lintner, Stéphane K.

    2013-11-01

    We present a novel methodology for the numerical solution of problems of diffraction by infinitely thin screens in three-dimensional space. Our approach relies on new integral formulations as well as associated high-order quadrature rules. The new integral formulations involve weighted versions of the classical integral operators related to the thin-screen Dirichlet and Neumann problems as well as a generalization to the open-surface problem of the classical Calderón formulae. The high-order quadrature rules we introduce for these operators, in turn, resolve the multiple Green function and edge singularities (which occur at arbitrarily close distances from each other, and which include weakly singular as well as hypersingular kernels) and thus give rise to super-algebraically fast convergence as the discretization sizes are increased. When used in conjunction with Krylov-subspace linear algebra solvers such as GMRES, the resulting solvers produce results of high accuracy in small numbers of iterations for low and high frequencies alike. We demonstrate our methodology with a variety of numerical results for screen and aperture problems at high frequencies—including simulation of classical experiments such as the diffraction by a circular disc (featuring in particular the famous Poisson spot), evaluation of interference fringes resulting from diffraction across two nearby circular apertures, as well as solution of problems of scattering by more complex geometries consisting of multiple scatterers and cavities.

  7. Figure and Dimension Metrology of Extremely Lightweight X-Ray Mirrors for Space Astronomy Applications

    Science.gov (United States)

    Zhang, William W.

    2010-01-01

    The International X-ray Observatory (IXO) is the next major space X-ray observatory, performing both imaging and spectroscopic studies of all kinds of objects in the Universe. It is a collaborative mission of the National Aeronautics and Space Administration of the United States, the European Space Agency, and Japan Aerospace Exploration Agency. It is to be launched into a Sun-Earth L2 orbit in 2021. One of the most challenging aspects of the mission is the construction of a flight mirror assembly capable focusing X-rays in the band of 0.1 to 40 keY with an angular resolution of better than 5 arc-seconds and with an effective collection area of more than 3 sq m. The mirror assembly will consist of approximately 15,000 parabolic and hyperbolic mirror segments, each of which is approximately 200mm by 300mm with a thickness of 0.4mm. The manufacture and qualification of these mirror segments and their integration into the giant mirror assembly have been the objectives of a vigorous technology development program at NASA's Goddard Space Flight Center. Each of these mirror segments needs to be measured and qualified for both optical figure and mechanical dimensions. In this talk, I will describe the technology program with a particular emphasis on a measurement system we are developing to meet those requirements, including the use of coordinate measuring machines, Fizeau interferometers, and custom-designed, and -built null lens. This system is capable of measuring highly off-axis aspherical or cylindrical mirrors with repeatability, accuracy, and speed.

  8. The status of lightweight photovoltaic space array technology based on amorphous silicon solar cells

    Science.gov (United States)

    Hanak, Joseph J.; Kaschmitter, Jim

    1991-01-01

    Ultralight, flexible photovoltaic (PV) array of amorphous silicon (a-Si) was identified as a potential low cost power source for small satellites. A survey was conducted of the status of the a-Si PV array technology with respect to present and future performance, availability, cost, and risks. For existing, experimental array blankets made of commercial cell material, utilizing metal foil substrates, the Beginning of Life (BOL) performance at Air Mass Zero (AM0) and 35 C includes total power up to 200 W, power per area of 64 W/sq m and power per weight of 258 W/kg. Doubling of power per weight occurs when polyimide substrates are used. Estimated End of Life (EOL) power output after 10 years in a nominal low earth orbit would be 80 pct. of BOL, the degradation being due to largely light induced effects (-10 to -15 pct.) and in part (-5 pct.) to space radiation. Predictions for the year 1995 for flexible PV arrays, made on the basis of published results for rigid a-Si modules, indicate EOL power output per area and per weight of 105 W/sq m and 400 W/kg, respectively, while predictions for the late 1990s based on existing U.S. national PV program goals indicate EOL values of 157 W/sq m and 600 W/kg. Cost estimates by vendors for 200 W ultralight arrays in volume of over 1000 units range from $100/watt to $125/watt. Identified risks include the lack of flexible, space compatible encapsulant, the lack of space qualification effort, recent partial or full acquisitions of US manufacturers of a-Si cells by foreign firms, and the absence of a national commitment for a long range development program toward developing of this important power source for space.

  9. High resolution inverse synthetic aperture radar imaging of three-axis-stabilized space target by exploiting orbital and sparse priors

    International Nuclear Information System (INIS)

    Ma Jun-Tao; Gao Mei-Guo; Xiong Di; Feng Qi; Guo Bao-Feng; Dong Jian

    2017-01-01

    The development of inverse synthetic aperture radar (ISAR) imaging techniques is of notable significance for monitoring, tracking and identifying space targets in orbit. Usually, a well-focused ISAR image of a space target can be obtained in a deliberately selected imaging segment in which the target moves with only uniform planar rotation. However, in some imaging segments, the nonlinear range migration through resolution cells (MTRCs) and time-varying Doppler caused by the three-dimensional rotation of the target would degrade the ISAR imaging performance, and it is troublesome to realize accurate motion compensation with conventional methods. Especially in the case of low signal-to-noise ratio (SNR), the estimation of motion parameters is more difficult. In this paper, a novel algorithm for high-resolution ISAR imaging of a space target by using its precise ephemeris and orbital motion model is proposed. The innovative contributions are as follows. 1) The change of a scatterer projection position is described with the spatial-variant angles of imaging plane calculated based on the orbital motion model of the three-axis-stabilized space target. 2) A correction method of MTRC in slant- and cross-range dimensions for arbitrarily imaging segment is proposed. 3) Coarse compensation for translational motion using the precise ephemeris and the fine compensation for residual phase errors by using sparsity-driven autofocus method are introduced to achieve a high-resolution ISAR image. Simulation results confirm the effectiveness of the proposed method. (paper)

  10. Aperture Averaging of Scintillation for Space-to-Ground Optical Communication Applications.

    Science.gov (United States)

    1983-08-15

    SCINTILLATION FOR SPACE-TO-GROUND OPTICAL COMUNICATION APPLICATIONS ........................ 5 REFERENCES...theoretical investigations necessary for the evaluation and applica- tion of scientific advances to now military space systems. Versatility and flexibility...systems. Expertise in the latest scientific developments is vital to the accomplishment of tasks related to these problems. The laboratories that con

  11. Lightweight structural design of a bolted case joint for the space shuttle solid rocket motor

    Science.gov (United States)

    Dorsey, John T.; Stein, Peter A.; Bush, Harold G.

    1988-01-01

    The structural design of a bolted joint with a static face seal which can be used to join Space Shuttle Solid Rocket Motor (SRM) case segments is given. Results from numerous finite element parametric studies indicate that the bolted joint meets the design requirement of preventing joint opening at the O-ring locations during SRM pressurization. A final design recommended for further development has the following parameters: 180 one-in.-diam. studs, stud centerline offset of 0.5 in radially inward from the shell wall center line, flange thickness of 0.75 in, bearing plate thickness of 0.25 in, studs prestressed to 70 percent of ultimate load, and the intermediate alcove. The design has a mass penalty of 1096 lbm, which is 164 lbm greater than the currently proposed capture tang redesign.

  12. High Speed, Low Cost Telemetry Access from Space Development Update on Programmable Ultra Lightweight System Adaptable Radio (PULSAR)

    Science.gov (United States)

    Simms, William Herbert, III; Varnavas, Kosta; Eberly, Eric

    2014-01-01

    Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 1990's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast, the foundations of transponder technology presently qualified for satellite applications were developed during the early space program of the 1960's. Conventional transponders are built to a specific platform and must be redesigned for every new bus while the SDR is adaptive in nature and can fit numerous applications with no hardware modifications. A SDR uses a minimum amount of analog / Radio Frequency (RF) components to up/down-convert the RF signal to/from a digital format. Once the signal is digitized, all processing is performed using hardware or software logic. Typical SDR digital processes include; filtering, modulation, up/down converting and demodulation. NASA Marshall Space Flight Center (MSFC) Programmable Ultra Lightweight System Adaptable Radio (PULSAR) leverages existing MSFC SDR designs and commercial sector enhanced capabilities to provide a path to a radiation tolerant SDR transponder. These innovations (1) reduce the cost of NASA Low Earth Orbit (LEO) and Deep Space standard transponders, (2) decrease power requirements, and (3) commensurately reduce volume. A second pay-off is the increased SDR flexibility by allowing the same hardware to implement multiple transponder types simply by altering hardware logic - no change of hardware is required - all of which will ultimately be accomplished in orbit. Development of SDR technology for space applications will provide a highly capable, low cost transponder to programs of all sizes. The MSFC PULSAR Project results in a Technology Readiness Level (TRL) 7 low-cost telemetry system available to Smallsat and CubeSat missions, as well as other platforms. This paper documents the continued development and

  13. Lightweight Robotic Excavation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Robust, lightweight, power-efficient excavation robots are mission enablers for lunar outposts and surface systems. Lunar excavators of this type cost-effectively...

  14. Approximate analytical method to evaluate diffraction crosstalk in free-space optical interconnects systems that use circular microlenses with finite uniform apertures

    Science.gov (United States)

    Al-Ababneh, Nedal

    2014-07-01

    We propose an accurate analytical model to calculate the optical crosstalk of a first-order free space optical interconnects system that uses microlenses with circular apertures. The proposed model is derived by evaluating the resulted finite integral in terms of an infinite series of Bessel functions. Compared to the model that uses complex Gaussian functions to expand the aperture function, it is shown that the proposed model is superior in estimating the crosstalk and provides more accurate results. Moreover, it is shown that the proposed model gives results close to that of the numerical model with superior computational efficiency.

  15. A Stepped Frequency CW SAR for Lightweight UAV Operation

    National Research Council Canada - National Science Library

    Morrison, Keith

    2005-01-01

    A stepped-frequency continuous wave (SF-CW) synthetic aperture radar (SAR), with frequency-agile waveforms and real-time intelligent signal processing algorithms, is proposed for operation from a lightweight UAV platform...

  16. Forecasting slope failures from space-based synthetic aperture radar (SAR) measurements

    Science.gov (United States)

    Wasowski, J.; Bovenga, F.; Nutricato, R.; Nitti, D. O.; Chiaradia, M. T.; Tijani, K.; Morea, A.

    2017-12-01

    New space-borne radar sensors enable multi-scale monitoring of potentially unstable slopes thanks to wide-area coverage (tens of thousands km2), regular long-term image acquisition schedule with increasing re-visit frequency (weekly to daily), and high measurement precision (mm). In particular, the recent radar satellite missions e.g., COSMO-SkyMed (CSK), Sentinel-1 (S-1) and improved multi-temporal interferometry (MTI) processing techniques allow timely delivery of information on slow ground surface displacements. Here we use two case study examples to show that it is possible to capture pre-failure slope strains through long-term MTI-based monitoring. The first case is a retrospective investigation of a huge 500ML m3 landslide, which occurred in Sept. 2016 in a large, active open-cast coal mine in central Europe. We processed over 100 S-1 images acquired since Fall 2014. The MTI results showed that the slope that failed had been unstable at least since 2014. Importantly, we detected consistent displacement trends and trend changes, which can be used for slope failure forecasting. Specifically, we documented significant acceleration in slope surface displacement in the two months preceding the catastrophic failure. The second case of retrospectively captured pre-failure slope strains regards our earlier study of a small 50 m long landslide, which occurred on Jan. 2014 and caused the derailment of a train on the railway line connecting NW Italy to France. We processed 56 CSK images acquired from Fall 2008 to Spring 2014. The MTI results revealed pre-failure displacements of the engineering structures on the slope subsequently affected by the 2014 slide. The analysis of the MTI time series further showed that the displacements had been occurring since 2009. This information could have been used to forewarn the railway authority about the slope instability hazard. The above examples indicate that more frequent and consistent image acquisitions by the new radar

  17. A synthetic aperture microwave radiometer to measure soil moisture and ocean salinity from space

    Science.gov (United States)

    Le Vine, D. M.; Hilliard, L. M.; Swift, C. T.; Ruf, C. S.; Garrett, L. B.

    1991-01-01

    A concept is presented for a microwave radiometer in space to measure soil moisture and ocean salinity as part of an 'Earth Probe' mission. The measurements could be made using an array of stick antennas. The L-band channel (1.4 GHz) would be the primary channel for determining soil moisture, with the S-band (2.65-GHz) and C-band (5.0-GHz) channels providing ancillary information to help correct for the effects of the vegetation canopy and possibly to estimate a moisture profile. A preliminary study indicates that an orbit at 450 km would provide coverage of better than 95 percent of the earth every 3 days. A 10-km resolution cell (at nadir) requires stick antennas about 9.5-m long at L-band. The S-band and C-band sticks would be substantially shorter (5 m and 2.7 m, respectively).

  18. Multiplier-free DCT approximations for RF multi-beam digital aperture-array space imaging and directional sensing

    International Nuclear Information System (INIS)

    Potluri, U S; Madanayake, A; Rajapaksha, N; Cintra, R J; Bayer, F M

    2012-01-01

    Multi-beamforming is an important requirement for broadband space imaging applications based on dense aperture arrays (AAs). Usually, the discrete Fourier transform is the transform of choice for AA electromagnetic imaging. Here, the discrete cosine transform (DCT) is proposed as an alternative, enabling the use of emerging fast algorithms that offer greatly reduced complexity in digital arithmetic circuits. We propose two novel high-speed digital architectures for recently proposed fast algorithms (Bouguezel, Ahmad and Swamy 2008 Electron. Lett. 44 1249–50) (BAS-2008) and (Cintra and Bayer 2011 IEEE Signal Process. Lett. 18 579–82) (CB-2011) that provide good approximations to the DCT at zero multiplicative complexity. Further, we propose a novel DCT approximation having zero multiplicative complexity that is shown to be better for multi-beamforming AAs when compared to BAS-2008 and CB-2011. The far-field array pattern of ideal DCT, BAS-2008, CB-2011 and proposed approximation are investigated with error analysis. Extensive hardware realizations, implementation details and performance metrics are provided for synchronous field programmable gate array (FPGA) technology from Xilinx. The resource consumption and speed metrics of BAS-2008, CB-2011 and the proposed approximation are investigated as functions of system word size. The 8-bit versions are mapped to emerging asynchronous FPGAs leading to significantly increased real-time throughput with clock rates at up to 925.6 MHz implying the fastest DCT approximations using reconfigurable logic devices in the literature. (paper)

  19. Technology development for the Advanced Technology Large Aperture Space Telescope (ATLAST) as a candidate large UV-Optical-Infrared (LUVOIR) surveyor

    Science.gov (United States)

    Bolcar, Matthew R.; Balasubramanian, Kunjithapatham; Clampin, Mark; Crooke, Julie; Feinberg, Lee; Postman, Marc; Quijada, Manuel; Rauscher, Bernard; Redding, David; Rioux, Norman; Shaklan, Stuart; Stahl, H. Philip; Stahle, Carl; Thronson, Harley

    2015-09-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) team has identified five key technologies to enable candidate architectures for the future large-aperture ultraviolet/optical/infrared (LUVOIR) space observatory envisioned by the NASA Astrophysics 30-year roadmap, Enduring Quests, Daring Visions. The science goals of ATLAST address a broad range of astrophysical questions from early galaxy and star formation to the processes that contributed to the formation of life on Earth, combining general astrophysics with direct-imaging and spectroscopy of habitable exoplanets. The key technologies are: internal coronagraphs, starshades (or external occulters), ultra-stable large-aperture telescopes, detectors, and mirror coatings. Selected technology performance goals include: 1x10-10 raw contrast at an inner working angle of 35 milli-arcseconds, wavefront error stability on the order of 10 pm RMS per wavefront control step, autonomous on-board sensing and control, and zero-read-noise single-photon detectors spanning the exoplanet science bandpass between 400 nm and 1.8 μm. Development of these technologies will provide significant advances over current and planned observatories in terms of sensitivity, angular resolution, stability, and high-contrast imaging. The science goals of ATLAST are presented and flowed down to top-level telescope and instrument performance requirements in the context of a reference architecture: a 10-meter-class, segmented aperture telescope operating at room temperature (~290 K) at the sun-Earth Lagrange-2 point. For each technology area, we define best estimates of required capabilities, current state-of-the-art performance, and current Technology Readiness Level (TRL) - thus identifying the current technology gap. We report on current, planned, or recommended efforts to develop each technology to TRL 5.

  20. A Nanotechnology Approach to Lightweight Multifunctional Polyethylene Composite Materials for Use Against the Space Environment, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Polyethylene-based composite materials are under consideration as multifunctional structural materials, with the expectation that they can provide radiation...

  1. High Efficency Lightweight Radiators, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — XC Associates proposes to build on prior work to develop and characterize a very high efficiency, lightweight radiator constructed from high thermal conductivity...

  2. Titanium Nanocomposite: Lightweight Multifunction Structural Material

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to research and develop lightweight metal matrix nanocomposites (MMnC) using a Titanium (Ti) metal matrix. Ti MMnC will crosscut the advancement of both...

  3. Lightweight and Energy Efficient Heat Pump, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Future Spacecraft from the JPL will require increasingly sophisticated thermal control technology. A need exists for efficient, lightweight Vapor Compression Cycle...

  4. Integrated electrochromic aperture diaphragm

    Science.gov (United States)

    Deutschmann, T.; Oesterschulze, E.

    2014-05-01

    In the last years, the triumphal march of handheld electronics with integrated cameras has opened amazing fields for small high performing optical systems. For this purpose miniaturized iris apertures are of practical importance because they are essential to control both the dynamic range of the imaging system and the depth of focus. Therefore, we invented a micro optical iris based on an electrochromic (EC) material. This material changes its absorption in response to an applied voltage. A coaxial arrangement of annular rings of the EC material is used to establish an iris aperture without need of any mechanical moving parts. The advantages of this device do not only arise from the space-saving design with a thickness of the device layer of 50μm. But it also benefits from low power consumption. In fact, its transmission state is stable in an open circuit, phrased memory effect. Only changes of the absorption require a voltage of up to 2 V. In contrast to mechanical iris apertures the absorption may be controlled on an analog scale offering the opportunity for apodization. These properties make our device the ideal candidate for battery powered and space-saving systems. We present optical measurements concerning control of the transmitted intensity and depth of focus, and studies dealing with switching times, light scattering, and stability. While the EC polymer used in this study still has limitations concerning color and contrast, the presented device features all functions of an iris aperture. In contrast to conventional devices it offers some special features. Owing to the variable chemistry of the EC material, its spectral response may be adjusted to certain applications like color filtering in different spectral regimes (UV, optical range, infrared). Furthermore, all segments may be switched individually to establish functions like spatial Fourier filtering or lateral tunable intensity filters.

  5. ULTRA-LIGHTWEIGHT CEMENT

    International Nuclear Information System (INIS)

    Fred Sabins

    2001-01-01

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Issues, Task 2: Review Russian Ultra-Lightweight Cement Literature, Task 3: Test Ultra-Lightweight Cements, and Task 8: Develop Field ULHS Cement Blending and Mixing Techniques. Results reported this quarter include: preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; summary of pertinent information from Russian ultra-lightweight cement literature review; laboratory tests comparing ULHS slurries to foamed slurries and sodium silicate slurries for two different applications; and initial laboratory studies with ULHS in preparation for a field job

  6. Evolving Design Criteria for Very Large Aperture Space-Based Telescopes and Their Influence on the Need for Integrated Tools in the Optimization Process

    Science.gov (United States)

    Arnold, William R., Sr.

    2015-01-01

    NASA's Advanced Mirror Technology Development (AMTD) program has been developing the means to design and build the future generations of space based telescopes. With the nearing completion of the James Webb Space Telescope (JWST), the astrophysics community is already starting to define the requirements for follow on observatories. The restrictions of available launch vehicles and the possibilities of planned future vehicles have fueled the competition between monolithic primaries (with better optical quality) and segmented primaries (with larger apertures, but with diffraction, costs and figure control issues). Regardless of the current shroud sizes and lift capacities, these competing architectures share the need for rapid design tools. As part of the AMTD program a number of tools have been developed and tested to speed up the design process. Starting with the Arnold Mirror Modeler (which creates Finite Element Models (FEM) for structural analysis) and now also feeds these models into thermal stability analyses. They share common file formats and interchangeable results. During the development of the program, numerous trade studies were created for 4 meter and 8 meter monolithic primaries, complete with support systems. Evaluation of these results has led to a better understanding of how the specification drives the results. This paper will show some of the early trade studies for typical specification requirements such as lowest mirror bending frequency and suspension system lowest frequency. The results use representative allowable stress values for each mirror substrate material and construction method and generic material properties. These studies lead to some interesting relationships between feasible designs and the realities of actually trying to build these mirrors. Much of the traditional specifications were developed for much smaller systems, where the mass and volume of the primary where a small portion of the overall satellite. JWST shows us that as

  7. Aperture area measurement facility

    Data.gov (United States)

    Federal Laboratory Consortium — NIST has established an absolute aperture area measurement facility for circular and near-circular apertures use in radiometric instruments. The facility consists of...

  8. Evolving Design Criteria for Very Large Aperture Space Based Telescopes and Their Influence on the Need for Integrated Tools in the Optimization Process

    Science.gov (United States)

    Arnold, William R., Sr.

    2015-01-01

    NASA's Advanced Mirror Technology Development (AMTD) program has been developing the means to design and build the future generations of space based telescopes. With the nearing completion of the James Webb Space Telescope (JWST), the astrophysics community is already starting to define the requirements for follow-on observatories. The restrictions of available launch vehicles and the possibilities of planned future vehicles have fueled the competition between monolithic primaries (with better optical quality) and segmented primaries (with larger apertures, but with diffraction, costs and figure control issues). Regardless of the current shroud sizes and lift capacities, these competing architectures share the need for rapid design tools. As part of the AMTD program a number of tools have been developed and tested to speed up the design process. Starting with the Arnold Mirror Modeler (which creates Finite Element Models (FEM) for structural analysis) and now also feeds these models into thermal stability analyses. They share common file formats and interchangeable results. During the development of the program, numerous trade studies were created for 4-meter and 8-meter monolithic primaries, complete with support systems. Evaluation of these results has led to a better understanding of how the specification drives the results. This paper will show some of the early trade studies for typical specification requirements such as lowest mirror bending frequency and suspension system lowest frequency. The results use representative allowable stress values for each mirror substrate material and construction method and generic material properties. These studies lead to some interesting relationships between feasible designs and the realities of actually trying to build these mirrors. Much of the traditional specifications were developed for much smaller systems, where the mass and volume of the primary where a small portion of the overall satellite. JWST shows us that as

  9. Overview and Recent Accomplishments of the Advanced Mirror Technology Development (AMTD) for Large Aperture UVOIR Space Telescopes Project

    Science.gov (United States)

    Stahl, H. Philip

    2013-01-01

    Per Astro2010, a new, larger UVO telescope is needed to answer fundamental scientific questions, such as: is there life on Earth-like exoplanets; how galaxies assemble stellar populations; how baryonic matter interacts with intergalactic medium; and how solar systems form and evolve. And, present technology is not mature enough to affordably build and launch any potential UVO concept. Advanced Mirror Technology Development (AMTD) is a funded SAT project. Our objective is to mature to TRL-6 the critical technologies needed to produce 4-m or larger flight-qualified UVOIR mirrors by 2018 so that a viable mission can be considered by the 2020 Decadal Review. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND result in a high-performance low-cost low-risk system. To provide the science community with options, we are pursuing multiple technology paths. We have assembled an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes. One of our key accomplishments is that we have derived engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicle and its inherent mass and volume constraints. We defined and initiated a program to mature 6 key technologies required to fabricate monolithic and segmented space mirrors.

  10. Imaging with Synthetic Aperture Radar

    CERN Document Server

    Massonnet, Didier

    2008-01-01

    Describing a field that has been transformed by the recent availability of data from a new generation of space and airborne systems, the authors offer a synthetic geometrical approach to the description of synthetic aperture radar, one that addresses physicists, radar specialists, as well as experts in image processing.  

  11. Light-weight plastination.

    Science.gov (United States)

    Steinke, Hanno; Rabi, Suganthy; Saito, Toshiyuki; Sawutti, Alimjan; Miyaki, Takayoshi; Itoh, Masahiro; Spanel-Borowski, Katharina

    2008-11-20

    Plastination is an excellent technique which helps to keep the anatomical specimens in a dry, odourless state. Since the invention of plastination technique by von Hagens, research has been done to improve the quality of plastinated specimens. In this paper, we have described a method of producing light-weight plastinated specimens using xylene along with silicone and in the final step, substitute xylene with air. The finished plastinated specimens were light-weight, dry, odourless and robust. This method requires less use of resin thus making the plastination technique more cost-effective. The light-weight specimens are easy to carry and can easily be used for teaching.

  12. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2001-10-23

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses tasks performed in the fourth quarter as well as the other three quarters of the past year. The subjects that were covered in previous reports and that are also discussed in this report include: Analysis of field laboratory data of active cement applications from three oil-well service companies; Preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; Summary of pertinent information from Russian ultra-lightweight cement literature review; and Comparison of compressive strengths of ULHS systems using ultrasonic and crush methods Results reported from the fourth quarter include laboratory testing of ULHS systems along with other lightweight cement systems--foamed and sodium silicate slurries. These comparison studies were completed for two different densities (10.0 and 11.5 lb/gal) and three different field application scenarios. Additional testing included the mechanical properties of ULHS systems and other lightweight systems. Studies were also performed to examine the effect that circulation by centrifugal pump during mixing has on breakage of ULHS.

  13. ULTRA-LIGHTWEIGHT CEMENT

    International Nuclear Information System (INIS)

    Fred Sabins

    2001-01-01

    The objective of this project is to develop an improved ultra-lightweight cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary of Halliburton Energy Services (HES) and BJ Services historical performance data for lightweight cement applications. These data are analyzed and compared to ULHS cement and foamed cement performances. Similar data is expected from Schlumberger, and an analysis of this data will be completed in the following phases of the project. Quality control testing of materials used to formulate ULHS cements in the laboratory was completed to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS and foamed cement. This protocol is presented and discussed. Results of further testing of ULHS cements are presented along with an analysis to establish cement performance design criteria to be used during the remainder of the project. Finally, a list of relevant literature on lightweight cement performance is compiled for review during the next quarter

  14. Mastering Apple Aperture

    CERN Document Server

    Fitzgerald, Thomas

    2013-01-01

    Written in a conversational style, the author will share his knowledge on advanced Aperture topics with detailed discussions of advanced topics, the theory behind some of those topics and lots of hints and tips for ways to improve your workflow.Photographer's who have a basic understanding of Aperture

  15. APT: Aperture Photometry Tool

    Science.gov (United States)

    Laher, Russ

    2012-08-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  16. Foamed Antenna Support for Very Large Apertures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase I program will demonstrate the feasibility of the in-space production of large aperture antenna structures. The use of a novel open cell foam,...

  17. Detailed IR aperture measurements

    CERN Document Server

    Bruce, Roderik; Garcia Morales, Hector; Giovannozzi, Massimo; Hermes, Pascal Dominik; Mirarchi, Daniele; Quaranta, Elena; Redaelli, Stefano; Rossi, Carlo; Skowronski, Piotr Krzysztof; Wretborn, Sven Joel; CERN. Geneva. ATS Department

    2016-01-01

    MD 1673 was carried out on October 5 2016, in order to investigate in more detail the available aperture in the LHC high-luminosity insertions at 6.5 TeV and β∗=40 cm. Previous aperture measurements in 2016 during commissioning had shown that the available aperture is at the edge of protection, and that the aperture bottleneck at β∗=40 cm in certain cases is found in the separation plane instead of in the crossing plane. Furthermore, the bottlenecks were consistently found in close to the upstream end of Q3 on the side of the incoming beam, and not in Q2 on the outgoing beam as expected from calculations. Therefore, this MD aimed at measuring IR1 and IR5 separately (at 6.5 TeV and β∗=40 cm, for 185 µrad half crossing angle), to further localize the bottlenecks longitudinally using newly installed BLMs, investigate the difference in aperture between Q2 and Q3, and to see if any aperture can be gained using special orbit bumps.

  18. Ultra-Lightweight Self-Deployable SMP Nanocomposite Sandwich for Habitat Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Space deployable and rigidizable structures that are ultra-lightweight, and have gas barrier property, space durability, and high impact resistance are desirable to...

  19. Self Deployable Ultra-Lightweight Modular Unit for Habitat Structural Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Space deployable and rigidizable structures which are ultra-lightweight, and have high rigidity, space durability, and high impact resistance are desirable to...

  20. Lightweight Phase-Change Material For Solar Power

    Science.gov (United States)

    Stark, Philip

    1993-01-01

    Lightweight panels containing phase-change materials developed for use as heat-storage elements of compact, lightweight, advanced solar dynamic power system. During high insolation, heat stored in panels via latent heat of fusion of phase-change material; during low insolation, heat withdrawn from panels. Storage elements consist mainly of porous carbon-fiber structures imbued with germanium. Developed for use aboard space station in orbit around Earth, also adapted to lightweight, compact, portable solar-power systems for use on Earth.

  1. Lightweight landscape enhancing design through minimal mass structures

    CERN Document Server

    Spinelli, Luigi; Monticelli, Carol; Pedrali, Paolo

    2016-01-01

    This book explains how lightweight materials and structures can be deployed in buildings to meet high environmental and aesthetic standards and emphasizes how the concept of lightness in building technology and design dovetails with the desire to enhance landscape. The first part of the book, on lightweight construction, aims to foster the use of membranes within the specific climatic context and in particular considers how lightweight materials and innovative technologies can enrich the quality of temporary spaces. The second part focuses exclusively on landscape, presenting novel approaches in the search for visual lightness and the quest to improve urban spaces. Particular attention is paid to the Italian experience, where the traditional appreciation of brick and stone has limited the scope for use of lightweight structures and membrane materials, often relegating them to a secondary or inappropriate role. The reader will come to appreciate how this attitude demeans a very advanced productive sector and n...

  2. Beam aperture modifier design with acoustic metasurfaces

    Science.gov (United States)

    Tang, Weipeng; Ren, Chunyu

    2017-10-01

    In this paper, we present a design concept of acoustic beam aperture modifier using two metasurface-based planar lenses. By appropriately designing the phase gradient profile along the metasurface, we obtain a class of acoustic convex lenses and concave lenses, which can focus the incoming plane waves and collimate the converging waves, respectively. On the basis of the high converging and diverging capability of these lenses, two kinds of lens combination scheme, including the convex-concave type and convex-convex type, are proposed to tune up the incoming beam aperture as needed. To be specific, the aperture of the acoustic beam can be shrunk or expanded through adjusting the phase gradient of the pair of lenses and the spacing between them. These lenses and the corresponding aperture modifiers are constructed by the stacking ultrathin labyrinthine structures, which are obtained by the geometry optimization procedure and exhibit high transmission coefficient and a full range of phase shift. The simulation results demonstrate the effectiveness of our proposed beam aperture modifiers. Due to the flexibility in aperture controlling and the simplicity in fabrication, the proposed modifiers have promising potential in applications, such as acoustic imaging, nondestructive evaluation, and communication.

  3. Lightweight enterprise architectures

    CERN Document Server

    Theuerkorn, Fenix

    2004-01-01

    STATE OF ARCHITECTUREArchitectural ChaosRelation of Technology and Architecture The Many Faces of Architecture The Scope of Enterprise Architecture The Need for Enterprise ArchitectureThe History of Architecture The Current Environment Standardization Barriers The Need for Lightweight Architecture in the EnterpriseThe Cost of TechnologyThe Benefits of Enterprise Architecture The Domains of Architecture The Gap between Business and ITWhere Does LEA Fit? LEA's FrameworkFrameworks, Methodologies, and Approaches The Framework of LEATypes of Methodologies Types of ApproachesActual System Environmen

  4. Security Isolation Strategy Mechanism for Lightweight Virtualization Environment

    Directory of Open Access Journals (Sweden)

    Liu Qian

    2017-01-01

    Full Text Available For cloud service providers, lightweight virtualization is a more economical way of virtualization. While the user is worried about the safety of applications and data of the container, due to the container sharing the underlying interface and the kernel, therefore the security and trusted degree of lightweight virtualization container isolation mechanism is critical for the promotion of lightweight virtualization service. Because the user cannot directly participate in the process of the construction and management of container isolation mechanism, it is difficult for them to establish confidence in the security and trusted degree of container isolation mechanism. Based on the research and analysis of system credible and virtualization isolation mechanism, this paper puts forward a set of lightweight virtualization security isolation strategy mechanism, divides lightweight virtualization container storage address space into several parts, puts forward the definition of lightweight virtualization security isolation, gives the formal description and proof of container security isolation strategy, and combines with related technology to verify the feasibility of lightweight virtualization security isolation strategy mechanism. The mechanism has important guiding significance for cloud services providers to deploy container security isolation.

  5. Spaceborne synthetic aperture radar: Current status and future directions. A report to the Committee on Earth Sciences, Space Studies Board, National Research Council

    Science.gov (United States)

    Evans, D. L. (Editor); Apel, J.; Arvidson, R.; Bindschadler, R.; Carsey, F.; Dozier, J.; Jezek, K.; Kasischke, E.; Li, F.; Melack, J.

    1995-01-01

    This report provides a context in which questions put forth by NASA's Office of Mission to Planet Earth (OMPTE) regarding the next steps in spaceborne synthetic aperture radar (SAR) science and technology can be addressed. It summarizes the state-of-the-art in theory, experimental design, technology, data analysis, and utilization of SAR data for studies of the Earth, and describes potential new applications. The report is divided into five science chapters and a technology assessment. The chapters summarize the value of existing SAR data and currently planned SAR systems, and identify gaps in observational capabilities needing to be filled to address the scientific questions. Cases where SAR provides complementary data to other (non-SAR) measurement techniques are also described. The chapter on technology assessment outlines SAR technology development which is critical not only to NASA's providing societally relevant geophysical parameters but to maintaining competitiveness in SAR technology, and promoting economic development.

  6. Aperture Photometry Tool

    Science.gov (United States)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

    2012-07-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source

  7. Lightweight superconducting alternators

    International Nuclear Information System (INIS)

    Keim, T.A.

    1988-01-01

    One of the most efficient and most lightweight means of converting high-temperature heat energy to electricity is a turboalternator set. Turboalternators are potentially important components of burst-mode power systems, either chemical or nuclear powered. Also, they are probable key components in future electric propulsion systems. Existing examples of multimegawatt turbomachines have been optimized for a variety of aerospace uses, ranging from aircraft propulsion to rocket engine fuel pump drives. There is no corresponding history of multimegawatt alternators built to aerospace standards of mass, performance, and reliability. This paper discusses one of the few such development efforts presently in progress, and gives an indication of possible future potential. In large power ratings, superconducting generators offer substantial power density, specific weight, and efficiency advantages over competing technologies. A program at GE has led to the construction of a lightweight high-voltage 20-MW generator with a superconducting field winding. The first part of this paper describes the design of the generator. The second projects the capabilities of the generator to other ratings

  8. The LHC dynamic aperture

    CERN Document Server

    Koutchouk, Jean-Pierre

    1999-01-01

    In 1996, the expected field errors in the dipoles and quadrupoles yielded a long-term dynamic aperture of some 8sigma at injection. The target was set to 12sigma to account for the limitations of our model (imperfections and dynamics). From scaling laws and tracking, a specification for the field imperfections yielding the target dynamic aperture was deduced. The gap between specification and expected errors is being bridged by i) an improvement of the dipole field quality, ii) a balance between geometric and persistent current errors, iii) additional correction circuits (a3 ,b4 ). With the goal in view, the emphasis has now turned to the sensitivity of the dynamic aperture to the optical parameters.The distortion of the dynamics at the lower amplitudes effectively reached by the particles is minimized by optimizing the distribution of the betatron phase advance. At collision energy, the dynamic aperture is limited by the field imperfections of the low-beta triplets, enhanced by the crossing angle. With corre...

  9. Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2008-01-01

    A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective is to im......A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective...... is to improve and obtain a more range independent lateral resolution compared to conventional dynamic receive focusing (DRF) without compromising frame rate. SASB is a two-stage procedure using two separate beamformers. First a set of Bmode image lines using a single focal point in both transmit and receive...... is stored. The second stage applies the focused image lines from the first stage as input data. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The performance of SASB with a static image object is compared with DRF...

  10. LIGHTWEIGHT CONCRETE BASED GRANSHLAK

    Directory of Open Access Journals (Sweden)

    NETESA M. I.

    2016-02-01

    Full Text Available Raising of problem. Concrete advisable to obtain a low strength with local secondary resources for recycling and reduce the environmental burden on the environment. But it is important to design such concrete compositions with a reduced flow of cement. It is known that the coefficient of efficiency of use of cement in the concrete of the heavy and B10 is less than about 0.5, which is almost two times smaller than in class B15 concrete and above. Even lower coefficient of efficiency in light concrete cement low strength. Therefore, it is important to find patterns determining the composition of lightweight concrete based on local-products industry with more efficient use of cement in them. Purpose.. Based on the analysis of earlier research results, including with the use of methods of mathematical planning of experiments to determine the concrete contents, which can provide the requirements for the underlying layers of the floor, the compressive strength of which should correspond to the class B5. It is important to provide the required strength at minimum flow of the cement, which is the most expensive and energy-intensive part of concrete. Conclusion. Analysis of the test results of control samples of concrete in 28-day-old, the following laws. The required tensile strength of concrete compressive strength of 7.0 MPa can be obtained in the test range when used in formulations as a filler as the Dnieper hydroelectric power station fly ash and tailings Krivoy Rog iron ore YuGOK. To ensure providing the required characteristic strength of the concrete in the underlying layers of the floor is advisable to use a nominal composition per cubic meter of concrete: cement 160 kg granshlaka Plant named after Petrovsky, 675 kg of fly ash Dnieper HPP 390 kg, 400 kg of sand, 230 liters of water. Thus, while ensuring rational grain composition components can obtain the desired strength lightweight concrete based granshlaka plant Petrovsky, using as fillers

  11. Computational imaging using lightweight diffractive-refractive optics

    KAUST Repository

    Peng, Yifan

    2015-11-23

    Diffractive optical elements (DOE) show great promise for imaging optics that are thinner and more lightweight than conventional refractive lenses while preserving their light efficiency. Unfortunately, severe spectral dispersion currently limits the use of DOEs in consumer-level lens design. In this article, we jointly design lightweight diffractive-refractive optics and post-processing algorithms to enable imaging under white light illumination. Using the Fresnel lens as a general platform, we show three phase-plate designs, including a super-thin stacked plate design, a diffractive-refractive-hybrid lens, and a phase coded-aperture lens. Combined with cross-channel deconvolution algorithm, both spherical and chromatic aberrations are corrected. Experimental results indicate that using our computational imaging approach, diffractive-refractive optics is an alternative candidate to build light efficient and thin optics for white light imaging.

  12. Computational imaging using lightweight diffractive-refractive optics

    KAUST Repository

    Peng, Yifan; Fu, Qiang; Amata, Hadi; Su, Shuochen; Heide, Felix; Heidrich, Wolfgang

    2015-01-01

    Diffractive optical elements (DOE) show great promise for imaging optics that are thinner and more lightweight than conventional refractive lenses while preserving their light efficiency. Unfortunately, severe spectral dispersion currently limits the use of DOEs in consumer-level lens design. In this article, we jointly design lightweight diffractive-refractive optics and post-processing algorithms to enable imaging under white light illumination. Using the Fresnel lens as a general platform, we show three phase-plate designs, including a super-thin stacked plate design, a diffractive-refractive-hybrid lens, and a phase coded-aperture lens. Combined with cross-channel deconvolution algorithm, both spherical and chromatic aberrations are corrected. Experimental results indicate that using our computational imaging approach, diffractive-refractive optics is an alternative candidate to build light efficient and thin optics for white light imaging.

  13. A lightweight universe?

    Science.gov (United States)

    Bahcall, Neta A.; Fan, Xiaohui

    1998-01-01

    How much matter is there in the universe? Does the universe have the critical density needed to stop its expansion, or is the universe underweight and destined to expand forever? We show that several independent measures, especially those utilizing the largest bound systems known—clusters of galaxies—all indicate that the mass-density of the universe is insufficient to halt the expansion. A promising new method, the evolution of the number density of clusters with time, provides the most powerful indication so far that the universe has a subcritical density. We show that different techniques reveal a consistent picture of a lightweight universe with only ∼20–30% of the critical density. Thus, the universe may expand forever. PMID:9600898

  14. Lightweight flywheel containment

    Science.gov (United States)

    Smith, James R.

    2004-06-29

    A lightweight flywheel containment composed of a combination of layers of various material which absorb the energy of a flywheel structural failure. The various layers of material act as a vacuum barrier, momentum spreader, energy absorber, and reaction plate. The flywheel containment structure has been experimentally demonstrated to contain carbon fiber fragments with a velocity of 1,000 m/s and has an aerial density of less than 6.5 g/square centimeters. The flywheel containment, may for example, be composed of an inner high toughness structural layer, and energy absorbing layer, and an outer support layer. Optionally, a layer of impedance matching material may be utilized intermediate the flywheel rotor and the inner high toughness layer.

  15. A Compact, Light-weight, Reliable and Highly Efficient Heat Pump for, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — RTI proposes to develop an efficient, reliable, compact and lightweight heat pump for space applications. The proposed effort is expected to lead to (at the end of...

  16. High Efficiency Advanced Lightweight Fuel Cell (HEAL-FC), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Infinity's High Efficiency Advanced Lightweight Fuel Cell (HEAL FC) is an improved version of its current fuel cell technology developed for space applications. The...

  17. Large-Scale Molded Silicon Oxycarbide Composite Components for Ultra-Low-Cost Lightweight Mirrors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Next-generation telescopes need mirrors that are extremely stable, lightweight, and affordable. Semplastics has developed a novel, innovative ceramic material which...

  18. Lightweight Ultrahigh Temperature CMC-Encased C/C Structure for Reentry and Hypersonic Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Future reentry and hypersonic vehicles require advanced lightweight leading edge thermal protection systems that can provide the dual functionality of...

  19. Survey of coded aperture imaging

    International Nuclear Information System (INIS)

    Barrett, H.H.

    1975-01-01

    The basic principle and limitations of coded aperture imaging for x-ray and gamma cameras are discussed. Current trends include (1) use of time varying apertures, (2) use of ''dilute'' apertures with transmission much less than 50%, and (3) attempts to derive transverse tomographic sections, unblurred by other planes, from coded images

  20. Congenital pyriform aperture stenosis

    International Nuclear Information System (INIS)

    Osovsky, Micky; Aizer-Danon, Anat; Horev, Gadi; Sirota, Lea

    2007-01-01

    Nasal airway obstruction is a potentially life-threatening condition in the newborn. Neonates are obligatory nasal breathers. The pyriform aperture is the narrowest, most anterior bony portion of the nasal airway, and a decrease in its cross-sectional area will significantly increase nasal airway resistance. Congenital nasal pyriform aperture stenosis (CNPAS) is a rare, unusual form of nasal obstruction. It should be considered in the differential diagnosis of any neonate or infant with signs and symptoms of upper airway compromise. It is important to differentiate this level of obstruction from the more common posterior choanal stenosis or atresia. CNPAS presents with symptoms of nasal airway obstruction, which are often characterized by episodic apnea and cyclical cyanosis. (orig.)

  1. The science case and data processing strategy for the Thinned Aperture Light Collector (TALC): a project for a 20 m far-infrared space telescope

    International Nuclear Information System (INIS)

    Sauvage, Marc; Durand, Gilles A.; Rodriguez, Louis R.; Starck, Jean-Luc; Ronayette, Samuel; Aussel, Herve; Minier, Vincent; Motte, Frederique; Pantin, Eric J.; Sureau, Florent

    2014-01-01

    The future of far-infrared observations rests on our capacity to reach sub-arc-second angular resolution around 100 μm, in order to achieve a significant advance with respect to our current capabilities. Furthermore, by reaching this angular resolution we can bridge the gap between capacities offered by the JWST in the near infrared and those allowed by ALMA in the submillimeter, and thus benefit from similar resolving capacities over the whole wavelength range where interstellar dust radiates and where key atomic and molecular transitions are found. In an accompanying paper, we present a concept of a deployable annular telescope, named TALC for Thinned Aperture Light Collector, reaching 20 m in diameter. Being annular, this telescope features a main beam width equivalent to that of a 27 m telescope, i.e. an angular resolution of 0.92'' at 100 μm. In this paper we focus on the science case of such a telescope as well on the aspects of unconventional data processing that come with this unconventional optical configuration. The principal science cases of TALC revolve around its imaging capacities, that allow resolving the Kuiper belt in extra-solar planetary systems, or the filamentary scale in star forming clouds all the way to the Galactic Center, or the Narrow Line Region in Active Galactic Nuclei of the Local Group, or breaking the confusion limit to resolve the Cosmic Infrared Background. Equipping this telescope with detectors capable of imaging polarimetry offers as well the extremely interesting perspective to study the influence of the magnetic field in structuring the interstellar medium. We will then present simulations of the optical performance of such a telescope. The main feature of an annular telescope is the small amount of energy contained in the main beam, around 30% for the studied configuration, and the presence of bright diffraction rings. Using simulated point spread functions for realistic broad-band filters, we study the observing

  2. Thermal Inertia Performance Evaluation of Light-Weighted Construction Space Envelopes Using Phase Change Materials in Mexico City’s Climate

    Directory of Open Access Journals (Sweden)

    Adriana Lira-Oliver

    2017-10-01

    Full Text Available The present study’s main objective was to determine the applicability of organic phase change materials (PCMs in a building’s envelope construction system for the passive provision of comfortable indoor thermal conditions over one year based on thermal inertia in Mexico City. Research on PCMs relate mainly to their use in building envelope construction systems to reduce energy consumption for mechanical indoor thermal conditioning—not in passive systems. Computer simulation results of mean indoor temperature variations are presented with the objective of evaluating these construction systems’ thermal inertia properties. In the present study, dynamic thermal simulations (DTS, using EnergyPlus software, of ten 1 m3 test units with envelope construction systems combining organic PCMs of different fusion temperatures with conventional materials were performed. Based on the results, it is concluded that the implementation of organic PCMs with a fusion temperature around 25 °C in combination with aerated concrete in a space envelope results in the highest number of hours the indoor temperatures remain within the comfort range throughout a typical year, due to the decrement of indoor temperature oscillations and, to a large extent, to thermal lag.

  3. The chaotic dynamical aperture

    International Nuclear Information System (INIS)

    Lee, S.Y.; Tepikian, S.

    1985-01-01

    Nonlinear magnetic forces become more important for particles in the modern large accelerators. These nonlinear elements are introduced either intentionally to control beam dynamics or by uncontrollable random errors. Equations of motion in the nonlinear Hamiltonian are usually non-integrable. Because of the nonlinear part of the Hamiltonian, the tune diagram of accelerators is a jungle. Nonlinear magnet multipoles are important in keeping the accelerator operation point in the safe quarter of the hostile jungle of resonant tunes. Indeed, all the modern accelerator design have taken advantages of nonlinear mechanics. On the other hand, the effect of the uncontrollable random multipoles should be evaluated carefully. A powerful method of studying the effect of these nonlinear multipoles is using a particle tracking calculation, where a group of test particles are tracing through these magnetic multipoles in the accelerator hundreds to millions of turns in order to test the dynamical aperture of the machine. These methods are extremely useful in the design of a large accelerator such as SSC, LEP, HERA and RHIC. These calculations unfortunately take tremendous amount of computing time. In this paper, we try to apply the existing method in the nonlinear dynamics to study the possible alternative solution. When the Hamiltonian motion becomes chaotic, the tune of the machine becomes undefined. The aperture related to the chaotic orbit can be identified as chaotic dynamical aperture. We review the method of determining chaotic orbit and apply the method to nonlinear problems in accelerator physics. We then discuss the scaling properties and effect of random sextupoles

  4. Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Gammelmark, Kim Løkke

    2006-01-01

    The paper describes the use of synthetic aperture (SA) imaging in medical ultrasound. SA imaging is a radical break with today's commercial systems, where the image is acquired sequentially one image line at a time. This puts a strict limit on the frame rate and the possibility of acquiring...... a sufficient amount of data for high precision flow estimation. These constrictions can be lifted by employing SA imaging. Here data is acquired simultaneously from all directions over a number of emissions, and the full image can be reconstructed from this data. The talk will demonstrate the many benefits...

  5. Microfabricated high-bandpass foucault aperture for electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Glaeser, Robert; Cambie, Rossana; Jin, Jian

    2014-08-26

    A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

  6. Lightweight Monorail Transport System

    Science.gov (United States)

    Weir, Harold F.; Wood, Kenneth E.; Strecker, Myron T.

    1987-01-01

    Report proposes monorail transportation system for zero-gravity environment. System carries materials and parts between locations on space station. Includes tubular rails instead of open channels usually found in overhead conveyor systems. Since resistance to torque of closed tube greater than that of open channel for same amount of material, tubular monorail designed for higher loads or for greater spacing between support points.

  7. Tibial valgus aperture osteotomy

    International Nuclear Information System (INIS)

    De los Rios G, Adolfo Leon; Saavedra Abadia, Adolfo Leon; Palacios, Julio

    2005-01-01

    This study is based on work carried out a The knee clinic at the arthroscopic surgery unit of the Institute of osteo-articular diseases, Imbanaco Medical Centre, The University Hospital of the Valle (Cali-Colombia) and The Fractures Clinic Ltd. (Palmira-Valle). This is a descriptive study, which demonstrates very positive outcomes for aperture osteotomy, without detracting from the importance of, and the progress made in uni-compartmental and total joint articular replacements of the knee. 10 patients were treated with a highs tibial open osteotomy between November 1988 and December 2002: 3 had post-traumatic deformities, without arthrosic alterations; 1 had pseudo-arthrosis caused by a failed corrective procedure; 1 had complex instability of the knee with osseous varus; 6 had a degenerative lesion of the medial meniscus with medial condral alterations. Follow-up was form 12 to 54 months. Treatment involved a tibial valgus aperture osteotomy and osteo-synthesis. Evaluation was carried out using the International Knee Documentation Committee (IKDC) scale, the For Special Surgery and The Knee Society Score

  8. Tissue Harmonic Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Rasmussen, Joachim

    The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB...

  9. Lightweight Light Sail Propulsion

    Data.gov (United States)

    National Aeronautics and Space Administration — The areal density of solar sails and laser sails is large due to the heavy support structure made of Mylar, Kapton or CP-1. Replacing this support structure with...

  10. Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk

    and the limiting factor is the amount of memory IO resources available. An equally high demand for memory throughput is found in the computer gaming industry, where a large part of the processing takes place on the graphics processing unit (GPU). Using the GPU, a framework for synthetic aperture imaging......Medical ultrasound imaging is used for many purposes, e.g. for localizing and classifying cysts, lesions, and other processes. Almost any mass is first observed using B-mode imaging and later classified using e.g. color flow, strain, or attenuation imaging. It is therefore important that the B......-mode images have high contrast. Like all imaging modalities, ultrasound is subject to a number of inherent artifacts that compromise image quality. The most prominent artifact is the degradation by coherent wave interference, known as “speckle”, which gives a granular appearance to an otherwise homogeneous...

  11. Transionospheric synthetic aperture imaging

    CERN Document Server

    Gilman, Mikhail; Tsynkov, Semyon

    2017-01-01

    This landmark monograph presents the most recent mathematical developments in the analysis of ionospheric distortions of SAR images and offers innovative new strategies for their mitigation. As a prerequisite to addressing these topics, the book also discusses the radar ambiguity theory as it applies to synthetic aperture imaging and the propagation of radio waves through the ionospheric plasma, including the anisotropic and turbulent cases. In addition, it covers a host of related subjects, such as the mathematical modeling of extended radar targets (as opposed to point-wise targets) and the scattering of radio waves off those targets, as well as the theoretical analysis of the start-stop approximation, which is used routinely in SAR signal processing but often without proper justification. The mathematics in this volume is clean and rigorous – no assumptions are hidden or ambiguously stated. The resulting work is truly interdisciplinary, providing both a comprehensive and thorough exposition of the field,...

  12. A new automatic synthetic aperture radar-based flood mapping application hosted on the European Space Agency's Grid Processing of Demand Fast Access to Imagery environment

    Science.gov (United States)

    Matgen, Patrick; Giustarini, Laura; Hostache, Renaud

    2012-10-01

    This paper introduces an automatic flood mapping application that is hosted on the Grid Processing on Demand (GPOD) Fast Access to Imagery (Faire) environment of the European Space Agency. The main objective of the online application is to deliver operationally flooded areas using both recent and historical acquisitions of SAR data. Having as a short-term target the flooding-related exploitation of data generated by the upcoming ESA SENTINEL-1 SAR mission, the flood mapping application consists of two building blocks: i) a set of query tools for selecting the "crisis image" and the optimal corresponding "reference image" from the G-POD archive and ii) an algorithm for extracting flooded areas via change detection using the previously selected "crisis image" and "reference image". Stakeholders in flood management and service providers are able to log onto the flood mapping application to get support for the retrieval, from the rolling archive, of the most appropriate reference image. Potential users will also be able to apply the implemented flood delineation algorithm. The latter combines histogram thresholding, region growing and change detection as an approach enabling the automatic, objective and reliable flood extent extraction from SAR images. Both algorithms are computationally efficient and operate with minimum data requirements. The case study of the high magnitude flooding event that occurred in July 2007 on the Severn River, UK, and that was observed with a moderateresolution SAR sensor as well as airborne photography highlights the performance of the proposed online application. The flood mapping application on G-POD can be used sporadically, i.e. whenever a major flood event occurs and there is a demand for SAR-based flood extent maps. In the long term, a potential extension of the application could consist in systematically extracting flooded areas from all SAR images acquired on a daily, weekly or monthly basis.

  13. Lightweight, Thermally Insulating Structural Panels

    Science.gov (United States)

    Eisen, Howard J.; Hickey, Gregory; Wen, Liang-Chi; Layman, William E.; Rainen, Richard A.; Birur, Gajanana C.

    1996-01-01

    Lightweight, thermally insulating panels that also serve as structural members developed. Honeycomb-core panel filled with low-thermal-conductivity, opacified silica aerogel preventing convection and minimizes internal radiation. Copper coating on face sheets reduces radiation. Overall thermal conductivities of panels smaller than state-of-art commercial non-structurally-supporting foam and fibrous insulations. On Earth, panels suitable for use in low-air-pressure environments in which lightweight, compact, structurally supporting insulation needed; for example, aboard high-altitude aircraft or in partially evacuated panels in refrigerators.

  14. Production of lightweight Geopolymer concrete using artificial local lightweight aggregate

    Directory of Open Access Journals (Sweden)

    Abbas Waleed

    2018-01-01

    Full Text Available Due to the rapid depletion of natural resources, the use of waste materials and by-products from different industries of building construction has been gaining increased attention. Geopolymer concrete based on Pozzolana is a new material that does not need the presence of Portland cement as a binder. The main focus of this research is to produce lightweight geopolymer concrete (LWGPC using artificial coarse lightweight aggregate which produced from locally available bentonite clays. In this investigation, the binder is low calcium fly ash (FA and the alkali activator is sodium hydroxide and sodium silicate in different molarities. The experimental tests including workability, fresh density, also, the compressive strength, splitting tensile strength, flexural strength, water absorption and ultrasonic pulse velocity at the age of 7, 28 and 56 days were studied. The oven dry density and thermal conductivity at 28 days age are investigated. The results show that it is possible to produce high strength lightweight geopolymer concrete successfully used as insulated structural lightweight concrete. The 28-day compressive strength, tensile strength, flexural strength, dry density, and thermal conductivity of the produced LWGPC are 35.8 MPa, 2.6MPa, 5.5 MPa, 1835kg/m3, and 0.9567 W/ (m. K, respectively.

  15. Range Compressed Holographic Aperture Ladar

    Science.gov (United States)

    2017-06-01

    entropy saturation behavior of the estimator is analytically described. Simultaneous range-compression and aperture synthesis is experimentally...4 2.1 Circular and Inverse -Circular HAL...2.3 Single Aperture, Multi-λ Imaging ...................................................................................... 14 2.4 Simultaneous Range

  16. Lightweight Hybrid Ablator Incorporating Aerogel-Filled Open-Cell Foam Structural Insulator, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In previous work for NASA and DoD, Ultramet developed lightweight open-cell foam insulators composed of a carbon or ceramic structural foam skeleton filled with a...

  17. Next Generation , Lightweight, Durable Boot Materials to Provide Active & Passive Thermal Protection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA Phase I SBIR program is to leverage lightweight, durable materials developed by NanoSonic for use within extra vehicular activity (EVA)...

  18. Ultra-Lightweight, High Efficiency Silicon-Carbide (SIC) Based Power Electronic Converters, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business of Innovation Research Phase I proposal seeks to investigate and prove the feasibility of developing highly efficient, ultra-lightweight SiC...

  19. Efficient Lightweight AC-AC Power Control for Solar UAV, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A highly efficient and lightweight dual bridge matrix power controller development is proposed that will provide high performance to a solar powered high altitude...

  20. Lightweight Design of an HTS Coil for the VASIMR Experiment, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Phase II SBIR contract Tai-Yang Research Company of Tennessee proposes to design, fabricate, and test an ultra-lightweight High Temperature Superconducting...

  1. Lightweight Ultrahigh Temperature CMC-Lined C/C Combustion Chambers, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA and DoD are seeking high-performance, lightweight liquid rocket combustion chambers with future performance goals that cannot be achieved using state-of-the-art...

  2. Lightweight and Compace Multifunction Computer-Controlled Strength and Aerobic Training Device, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TDA Research proposes to develop a computer-controlled lightweight and compact device for aerobic and resistive training (DART) to counteract muscular atrophy and...

  3. Silicon Carbide Lightweight Optics With Hybrid Skins for Large Cryo Telescopes, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical Physics Company (OPC) has developed new silicon carbide (SiC) foam-based optics with hybrid skins that are composite, athermal and lightweight (FOCAL) that...

  4. Silicon Carbide Lightweight Optics With Hybrid Skins for Large Cryo Telescopes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical Physics Company (OPC) proposes to manufacture new silicon carbide (SiC) foam-based optics that are composite, athermal and lightweight (FOCAL) that provide...

  5. Spongent: A lightweight hash function

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Knežević, Miroslav; Leander, Gregor

    2011-01-01

    This paper proposes spongent - a family of lightweight hash functions with hash sizes of 88 (for preimage resistance only), 128, 160, 224, and 256 bits based on a sponge construction instantiated with a present-type permutation, following the hermetic sponge strategy. Its smallest implementations...

  6. FY2016 Lightweight Materials Annual Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2017-10-31

    The Lightweight Materials research and development (R&D) area within the DOE Vehicle Technologies Office (VTO) provides support and guidance for many cutting-edge automotive technologies under development. Research focuses on addressing critical barriers to commercializing lightweight materials for passenger and commercial vehicles. This report describes the progress made on the research and development projects funded by the Lightweight Materials area.

  7. Lightweighted ZERODUR for telescopes

    Science.gov (United States)

    Westerhoff, T.; Davis, M.; Hartmann, P.; Hull, T.; Jedamzik, R.

    2014-07-01

    The glass ceramic ZERODUR® from SCHOTT has an excellent reputation as mirror blank material for earthbound and space telescope applications. It is known for its extremely low coefficient of thermal expansion (CTE) at room temperature and its excellent CTE homogeneity. Recent improvements in CNC machining at SCHOTT allow achieving extremely light weighted substrates up to 90% incorporating very thin ribs and face sheets. In 2012 new ZERODUR® grades EXPANSION CLASS 0 SPECIAL and EXTREME have been released that offer the tightest CTE grades ever. With ZERODUR® TAILORED it is even possible to offer ZERODUR® optimized for customer application temperature profiles. In 2013 SCHOTT started the development of a new dilatometer setup with the target to drive the industrial standard of high accuracy thermal expansion metrology to its limit. In recent years SCHOTT published several paper on improved bending strength of ZERODUR® and lifetime evaluation based on threshold values derived from 3 parameter Weibull distribution fitted to a multitude of stress data. ZERODUR® has been and is still being successfully used as mirror substrates for a large number of space missions. ZERODUR® was used for the secondary mirror in HST and for the Wolter mirrors in CHANDRA without any reported degradation of the optical image quality during the lifetime of the missions. Some years ago early studies on the compaction effects of electron radiation on ZERODUR® were re analyzed. Using a more relevant physical model based on a simplified bimetallic equation the expected deformation of samples exposed in laboratory and space could be predicted in a much more accurate way. The relevant ingredients for light weighted mirror substrates are discussed in this paper: substrate material with excellent homogeneity in its properties, sufficient bending strengths, space radiation hardness and CNC machining capabilities.

  8. Ultra-low Cost, Lightweight, Molded, Chalcogenide Glass-Silicon Oxycarbide Composite Mirror Components, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — After optical performance, the most important metric for advanced optical systems is the areal cost (cost per square meter of collecting aperture). Future NASA space...

  9. A comparison of performance of lightweight mirrors

    Science.gov (United States)

    Cho, Myung K.; Richard, Ralph M.; Hileman, Edward A.

    1990-01-01

    Four lightweight solid contoured back mirror shapes (a double arch, a single arch, a modified single arch, and a double concave mirror) and a cellular sandwich lightweight meniscus mirror, have been considered for the primary mirror of the Space Infrared Telescope Facility (SIRTF). A parametric design study using these shapes for the SIRTF 40 inch primary mirror with a focal ratio f/2 is presented. Evaluations of the optical performance and fundamental frequency analyses are performed to compare relative merits of each mirror configuration. Included in these are structural, optical, and frequency analyses for (1) different back contour shapes, (2) different number and location of the support points, and (3) two gravity orientations (ZENITH and HORIZON positions). The finite element program NASTRAN is used to obtain the structural deflections of the optical surface. For wavefront error analysis, FRINGE and PCFRINGE programs are used to evaluate the optical performance. A scaling law relating the optical and structural performance for various mirror contoured back shapes is developed.

  10. Coded aperture tomography revisited

    International Nuclear Information System (INIS)

    Bizais, Y.; Rowe, R.W.; Zubal, I.G.; Bennett, G.W.; Brill, A.B.

    1983-01-01

    Coded aperture (CA) Tomography never achieved wide spread use in Nuclear Medicine, except for the degenerate case of Seven Pinhole tomagraphy (7PHT). However it enjoys several attractive features (high sensitivity and tomographic ability with a statis detector). On the other hand, resolution is usually poor especially along the depth axis and the reconstructed volume is rather limited. Arguments are presented justifying the position that CA tomography can be useful for imaging time-varying 3D structures, if its major drawbacks (poor longitudinal resolution and difficulty in quantification) are overcome. Poor results obtained with 7PHT can be explained by both a very limited angular range sampled and a crude modelling of the image formation process. Therefore improvements can be expected by the use of a dual-detector system, along with a better understanding of its sampling properties and the use of more powerful reconstruction algorithms. Non overlapping multipinhole plates, because they do not involve a decoding procedure, should be considered first for practical applications. Use of real CA should be considered for cases in which non overlapping multipinhole plates do not lead to satisfactory solutions. We have been and currently are carrying out theoretical and experimental works, in order to define the factors which limit CA imaging and to propose satisfactory solutions for Dynamic Emission Tomography

  11. Aperture modulated arc therapy

    International Nuclear Information System (INIS)

    Crooks, S M; Wu, Xiaodong; Takita, C; Watzich, M; Xing Lei

    2003-01-01

    We show that it is possible to translate an intensity modulated radiation therapy (IMRT) treatment plan and deliver it as a single arc. This technique is referred to in this paper as aperture modulation arc therapy (AMAT). During this arc, the MLC leaves do not conform to the projection of the target PTV and the machine output of the accelerator has a constant value. Dose was calculated using the CORVUS 4.0 IMRT system, which uses a pencil beam dose algorithm, and treatments were delivered using a Varian 2100C/D Clinac. Results are presented for a head and neck and a prostate case, showing the equivalence of the IMRT and the translated AMAT delivery. For a prostate AMAT delivery, coronal plane film dose for the IMRT and AMAT deliveries agreed within 7.19 ± 6.62%. For a meningioma the coronal plane dose distributions were similar to a value of 4.6 ± 6.62%. Dose to the isocentre was measured as being within 2% of the planned value in both cases

  12. Wind retrieval from synthetic aperture radar - an overview

    DEFF Research Database (Denmark)

    Dagestad, Knut-Frode; Horstmann, Jochen; Mouche, Alexis

    2013-01-01

    This paper represents a consensus on the state-of-the-art in wind retrieval using synthetic aperture radar (SAR), after the SEASAR 2012 workshop “Advances in SAR Oceanography” hosted by the European Space Agency (ESA) and the Norwegian Space Centre in Tromsø, Norway 18–22 June 2012. We document...

  13. Fast-neutron, coded-aperture imager

    Science.gov (United States)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  14. Large aperture optical switching devices

    International Nuclear Information System (INIS)

    Goldhar, J.; Henesian, M.A.

    1983-01-01

    We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

  15. Experimental research on reinforced lightweight plugging composites.

    Directory of Open Access Journals (Sweden)

    BEKBAEV Arstan Abaevich

    2017-08-01

    Full Text Available Practical aspects of the well construction show that the use of conventional cementing materials do not always provide the necessary level of quality of well casing when the requirements to resources conservation are enhanced. This is true for such complex geological conditions as the alternation of beds with different formation pressures, low fracturing pressure gradients, drilling with ERD tc. The main problems in well casing under these conditions are the losses of cement slurries, low cement top, low-quality formation isolation, and as the result of this – the emergence of cross-flows. The high quality of well casing will be provided only by means of safe contact between cement stone and limiting surfaces (casing and rock, therefore to use expansion materials for cementing is a well-recognized method. Thus, it is obvious that their application does not give positive results for intervals with a thick filter cake or intervals with cavities, i.e. where space for expansion is greater than the magnitude of the expansion. At the same time it is very challenging to create high-quality cement in formations with abnormally low formation pressure or low fracture gradient. The solution of this problem is the use of lightweight cements, which scarcely expand while hardening. This is due to the fact that lightweight cement slurries are generally obtained by increasing the content of grouting fluid in the solution, resulting in increase of the distance between the crystal hydrates – hardening products, that leads to decrease of crystallization pressure of expansion agents on the space frame of the cement stone]. Moreover, such works as secondary reservoir developing (perforation, well completion and fracturing operations create high dynamic load on the cement stone, which leads to its destruction. The stone can be completely destroyed, that often causes premature flooding of wells and incurring additional costs. In this regard, it is necessary to

  16. Lightweight design: mass in transit

    OpenAIRE

    MALBURET, François; KRYSINSKI, Tomasz; NAUZIN, Jean-Paul

    2012-01-01

    This paper is part of an effort to reduce a vehicle’s CO2 emissions through lightweight design. The originality of the approach consists in harnessing the optimal vehicle architecture with regard to CO2 emissions. Reducing a vehicle’s weight provides an opportunity to reassess performance features like shock, noise, vibrations and road holding, thereby generating additional savings through a virtuous cycle of weight reduction. The paper sheds light on some methodological aspects used by PSA P...

  17. Applications of Foamed Lightweight Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Sari Kamarul Aini

    2017-01-01

    Full Text Available Application of foamed concrete is increasing at present due to high demand on foamed concrete structures with good mechanical and physical properties. This paper discusses on the use of basic raw materials, their characteristics, production process, and their application in foamed lightweight concrete with densities between 300 kg/m3 and 1800 kg/m3. It also discusses the factors that influence the strengths and weaknesses of foamed concrete based on studies that were conducted previously.

  18. Lightweight cryptography for constrained devices

    DEFF Research Database (Denmark)

    Alippi, Cesare; Bogdanov, Andrey; Regazzoni, Francesco

    2014-01-01

    Lightweight cryptography is a rapidly evolving research field that responds to the request for security in resource constrained devices. This need arises from crucial pervasive IT applications, such as those based on RFID tags where cost and energy constraints drastically limit the solution...... complexity, with the consequence that traditional cryptography solutions become too costly to be implemented. In this paper, we survey design strategies and techniques suitable for implementing security primitives in constrained devices....

  19. Sea Ice Movements from Synthetic Aperture Radar

    Science.gov (United States)

    1981-12-01

    correlating these components. B-l8 These correlations are also plotted in figure l1. 5.3.3.2 AUlications of the space correlation. The spatial...aperture radar. To appear in J. of Geophys. Res. Hastings, A. D. Jr., 1971. Surface climate of the Arctic Basin. Report ETL- TR-71-5, Earth Sciences Division...Administration Grant NA50-AA-D-00015, which was funded in part by the Global Atmospheric Research Program and the Office of Climate Dynarics, Divisic

  20. NIAC Phase II Orbiting Rainbows: Future Space Imaging with Granular Systems

    Science.gov (United States)

    Quadrelli, Marco B.; Basinger, Scott; Arumugam, Darmindra; Swartzlander, Grover

    2017-01-01

    Inspired by the light scattering and focusing properties of distributed optical assemblies in Nature, such as rainbows and aerosols, and by recent laboratory successes in optical trapping and manipulation, we propose a unique combination of space optics and autonomous robotic system technology, to enable a new vision of space system architecture with applications to ultra-lightweight space optics and, ultimately, in-situ space system fabrication. Typically, the cost of an optical system is driven by the size and mass of the primary aperture. The ideal system is a cloud of spatially disordered dust-like objects that can be optically manipulated: it is highly reconfigurable, fault-tolerant, and allows very large aperture sizes at low cost. This new concept is based on recent understandings in the physics of optical manipulation of small particles in the laboratory and the engineering of distributed ensembles of spacecraft swarms to shape an orbiting cloud of micron-sized objects. In the same way that optical tweezers have revolutionized micro- and nano-manipulation of objects, our breakthrough concept will enable new large scale NASA mission applications and develop new technology in the areas of Astrophysical Imaging Systems and Remote Sensing because the cloud can operate as an adaptive optical imaging sensor. While achieving the feasibility of constructing one single aperture out of the cloud is the main topic of this work, it is clear that multiple orbiting aerosol lenses could also combine their power to synthesize a much larger aperture in space to enable challenging goals such as exo-planet detection. Furthermore, this effort could establish feasibility of key issues related to material properties, remote manipulation, and autonomy characteristics of cloud in orbit. There are several types of endeavors (science missions) that could be enabled by this type of approach, i.e. it can enable new astrophysical imaging systems, exo-planet search, large apertures

  1. First TSI observations of the new Compact Lightweight Absolute Radiometer (CLARA)

    Science.gov (United States)

    Walter, B.; Finsterle, W.; Koller, S.; Levesque, P. L.; Pfiffner, D.; Schmutz, W. K.

    2017-12-01

    Continuous and precise Total Solar Irradiance (TSI) measurements are indispensable to evaluate the influence of short- and long-term solar radiative emission variations on the Earth's energy budget. The existence of a potentially long-term trend in the suns activity and whether or not such a trend could be climate effective is still a matter of debate. The Compact Lightweight Absolute Radiometer (CLARA) is one of PMOD/WRC's future contributions to the almost seamless series of space borne TSI measurements since 1978. CLARA is one of three payloads of the Norwegian micro satellite NORSAT-1, along with Langmuir probes for space plasma research and an Automatic Identification System (AIS) receiver to monitor maritime traffic in Norwegian waters. NORSAT-1 was launched July 14th 2017 and the nominal operation of CLARA will start after the instrument commissioning beginning August 21st2017. We present the design, calibration and first TSI observations of CLARA, a new generation of active cavity Electrical Substitution Radiometers (ESR) comprising the latest radiometer developments of PMOD/WRC: i) A three-cavity design for degradation tracking and redundancy, ii) a digital control loop with feed forward system allowing for measurement cadences of 30s, iii) an aperture arrangement to reduce internal scattered light and iv) a new cavity and heatsink design to minimize non-equivalence, size and weight of the instrument. CLARA was end-to-end calibrated against the SI traceable cryogenic radiometer of the TSI Radiometer Facility (TRF) in Boulder (Colorado). The absolute measurement uncertainties for the three SI-traceable TSI detectors of CLARA are 567, 576 and 912 ppm (k = 1).

  2. Lightweight Bathrooms with Increased Durability

    DEFF Research Database (Denmark)

    Morelli, Martin; Brandt, Erik

    2017-01-01

    vulnerable and less robust than the old type of heavy wet rooms made from concrete and masonry. For example damage due to ingress of water and moisture in a lightweight construction is normally associated with very expensive repair work. However, they might perform fully satisfactorily on condition...... wet room floor made with 2 watertight layers separated by an inorganic layer e.g. fibre reinforced concrete. Both layers are drained to the floor gully in order to reduce the risk of damage from leaks in the watertight layer; i.e. if one layer fails, the layer beneath will be able to provide...

  3. Fast-neutron, coded-aperture imager

    International Nuclear Information System (INIS)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-01-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  4. Fast-neutron, coded-aperture imager

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F., E-mail: bernard.phlips@nrl.navy.mil; Hutcheson, Anthony L., E-mail: anthony.hutcheson@nrl.navy.mil; Wulf, Eric A., E-mail: eric.wulf@nrl.navy.mil

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  5. Spaceborne L-band Radiometers: Push-broom or Synthetic Aperture?

    DEFF Research Database (Denmark)

    Skou, Niels

    2004-01-01

    L-band radiometers can measure ocean salinity and soil moisture from space. A synthetic aperture radiometer system, SMOS, is under development by ESA for launch in 2007. A real aperture push-broom system, Aquarius, has been approved by NASA for launch in 2008. Pros et cons of the two fundamentally...

  6. Nonparaxial propagation and focusing properties of azimuthal-variant vector fields diffracted by an annular aperture.

    Science.gov (United States)

    Gu, Bing; Xu, Danfeng; Pan, Yang; Cui, Yiping

    2014-07-01

    Based on the vectorial Rayleigh-Sommerfeld integrals, the analytical expressions for azimuthal-variant vector fields diffracted by an annular aperture are presented. This helps us to investigate the propagation behaviors and the focusing properties of apertured azimuthal-variant vector fields under nonparaxial and paraxial approximations. The diffraction by a circular aperture, a circular disk, or propagation in free space can be treated as special cases of this general result. Simulation results show that the transverse intensity, longitudinal intensity, and far-field divergence angle of nonparaxially apertured azimuthal-variant vector fields depend strongly on the azimuthal index, the outer truncation parameter and the inner truncation parameter of the annular aperture, as well as the ratio of the waist width to the wavelength. Moreover, the multiple-ring-structured intensity pattern of the focused azimuthal-variant vector field, which originates from the diffraction effect caused by an annular aperture, is experimentally demonstrated.

  7. High-flexibility, noncollapsing lightweight hose

    Science.gov (United States)

    Williams, D.A.

    1993-04-20

    A high-flexibility, noncollapsing, lightweight, large-bore, wire-reinforced hose is inside fiber-reinforced PVC tubing that is flexible, lightweight, and abrasion resistant. It provides a strong, kink- and collapse-free conduit for moving large quantities of dangerous fluids, e.g., removing radioactive waste water or processing chemicals.

  8. A Lightweight Compact Multi-Spectral Imager Using Novel Computer-Generated Micro-Optics and Spectral-Extraction Algorithms

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA Early-stage research proposal is to demonstrate an ultra-compact, lightweight broadband hyper- and multi-spectral imaging system that is...

  9. Lightweight Ultrahigh Temperature CMC-Encased C/C Structure for Reentry and Hypersonic Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The reentry spacecraft and hypersonic cruisers of the future will require advanced lightweight thermal protection systems that can provide the dual functionality of...

  10. Dynamic aperture and transverse proton diffusion in HERA

    International Nuclear Information System (INIS)

    Zimmermann, F.

    1994-04-01

    The dynamic aperture caused by persistent-current nonlinear field errors is an important concern in the design of superconducting hadron storage rings. The HERA proton ring is the second superconducting accelerator in operation. In this lecture note, its measured dynamic aperture is compared with that inferred from comprehensive trackig studies. To understand the difference between prediction and measurement, a semi-analytical method is developed for evaluating transverse diffusion rates due to various processes, such as modulational diffusion or sweeping diffusion this analysis makes use of parameters for high-order resonances in the transverse phase space, which are obtained by normal-form algorithms using differential-algebra software. This semi-analytical results are consistent wit the measurements, and suggest that the actual dynamic aperture is caused by an interplay of tune modulation and nonlinear magnetic fields

  11. Medium-sized aperture camera for Earth observation

    Science.gov (United States)

    Kim, Eugene D.; Choi, Young-Wan; Kang, Myung-Seok; Kim, Ee-Eul; Yang, Ho-Soon; Rasheed, Ad. Aziz Ad.; Arshad, Ahmad Sabirin

    2017-11-01

    Satrec Initiative and ATSB have been developing a medium-sized aperture camera (MAC) for an earth observation payload on a small satellite. Developed as a push-broom type high-resolution camera, the camera has one panchromatic and four multispectral channels. The panchromatic channel has 2.5m, and multispectral channels have 5m of ground sampling distances at a nominal altitude of 685km. The 300mm-aperture Cassegrain telescope contains two aspheric mirrors and two spherical correction lenses. With a philosophy of building a simple and cost-effective camera, the mirrors incorporate no light-weighting, and the linear CCDs are mounted on a single PCB with no beam splitters. MAC is the main payload of RazakSAT to be launched in 2005. RazakSAT is a 180kg satellite including MAC, designed to provide high-resolution imagery of 20km swath width on a near equatorial orbit (NEqO). The mission objective is to demonstrate the capability of a high-resolution remote sensing satellite system on a near equatorial orbit. This paper describes the overview of the MAC and RarakSAT programmes, and presents the current development status of MAC focusing on key optical aspects of Qualification Model.

  12. RFID security a lightweight paradigm

    CERN Document Server

    Khattab, Ahmed; Amini, Esmaeil; Bayoumi, Magdy

    2017-01-01

    This book provides a comprehensive treatment of security in the widely adopted, Radio Frequency Identification (RFID) technology. The authors present the fundamental principles of RFID cryptography in a manner accessible to a broad range of readers, enabling them to improve their RFID security design. This book also offers the reader a range of interesting topics portraying the current state-of-the-art in RFID technology and how it can be integrated with today’s Internet of Things (IoT) vision. The authors describe a first-of-its-kind, lightweight symmetric authenticated encryption cipher called Redundant Bit Security (RBS), which enables significant, multi-faceted performance improvements compared to existing cryptosystems. This book is a must-read for anyone aiming to overcome the constraints of practical implementation in RFID security technologies.

  13. Algorithms for Lightweight Key Exchange.

    Science.gov (United States)

    Alvarez, Rafael; Caballero-Gil, Cándido; Santonja, Juan; Zamora, Antonio

    2017-06-27

    Public-key cryptography is too slow for general purpose encryption, with most applications limiting its use as much as possible. Some secure protocols, especially those that enable forward secrecy, make a much heavier use of public-key cryptography, increasing the demand for lightweight cryptosystems that can be implemented in low powered or mobile devices. This performance requirements are even more significant in critical infrastructure and emergency scenarios where peer-to-peer networks are deployed for increased availability and resiliency. We benchmark several public-key key-exchange algorithms, determining those that are better for the requirements of critical infrastructure and emergency applications and propose a security framework based on these algorithms and study its application to decentralized node or sensor networks.

  14. Adjustable liquid aperture to eliminate undesirable light in holographic projection.

    Science.gov (United States)

    Wang, Di; Liu, Chao; Li, Lei; Zhou, Xin; Wang, Qiong-Hua

    2016-02-08

    In this paper, we propose an adjustable liquid aperture to eliminate the undesirable light in a holographic projection. The aperture is based on hydrodynamic actuation. A chamber is formed with a cylindrical tube. A black droplet is filled in the sidewall of the cylinder tube and the outside space is the transparent oil which is immiscible with the black droplet. An ultrathin glass sheet is attached on the bottom substrate of the device and a black shading film is secured to the central area of the glass sheet. By changing the volume of the black droplet, the black droplet will move to the middle or sidewall due to hydrodynamic actuation, so the device can be used as an adjustable aperture. A divergent spherical wave and a solid lens are used to separate the focus planes of the reconstructed image and diffraction beams induced by the liquid crystal on silicon in the holographic projection. Then the aperture is used to eliminate the diffraction beams by adjusting the size of the liquid aperture and the holographic projection does not have undesirable light.

  15. Surface accuracy analysis and mathematical modeling of deployable large aperture elastic antenna reflectors

    Science.gov (United States)

    Coleman, Michael J.

    One class of deployable large aperture antenna consists of thin light-weight parabolic reflectors. A reflector of this type is a deployable structure that consists of an inflatable elastic membrane that is supported about its perimeter by a set of elastic tendons and is subjected to a constant hydrostatic pressure. A design may not hold the parabolic shape to within a desired tolerance due to an elastic deformation of the surface, particularly near the rim. We can compute the equilibrium configuration of the reflector system using an optimization-based solution procedure that calculates the total system energy and determines a configuration of minimum energy. Analysis of the equilibrium configuration reveals the behavior of the reflector shape under various loading conditions. The pressure, film strain energy, tendon strain energy, and gravitational energy are all considered in this analysis. The surface accuracy of the antenna reflector is measured by an RMS calculation while the reflector phase error component of the efficiency is determined by computing the power density at boresight. Our error computation methods are tailored for the faceted surface of our model and they are more accurate for this particular problem than the commonly applied Ruze Equation. Previous analytical work on parabolic antennas focused on axisymmetric geometries and loads. Symmetric equilibria are not assumed in our analysis. In addition, this dissertation contains two principle original findings: (1) the typical supporting tendon system tends to flatten a parabolic reflector near its edge. We find that surface accuracy can be significantly improved by fixing the edge of the inflated reflector to a rigid structure; (2) for large membranes assembled from flat sheets of thin material, we demonstrate that the surface accuracy of the resulting inflated membrane reflector can be improved by altering the cutting pattern of the flat components. Our findings demonstrate that the proper choice

  16. Aperture measurements with AC dipole

    CERN Document Server

    Fuster Martinez, Nuria; Dilly, Joschua Werner; Nevay, Laurence James; Bruce, Roderik; Tomas Garcia, Rogelio; Redaelli, Stefano; Persson, Tobias Hakan Bjorn; CERN. Geneva. ATS Department

    2018-01-01

    During the MDs performed on the 15th of September and 29th of November 2017, we measured the LHC global aperture at injection with a new AC dipole method as well as using the Transverse Damper (ADT) blow-up method used during the 2017 LHC commissioning for benchmarking. In this note, the MD procedure is presented as well as the analysis of the comparison between the two methods. The possible benefits of the new method are discussed.

  17. Graphene for Expandable Space Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Graphene's tightly bonded impermeable single atomic layer of carbon offers unrivalled potential for lightweight flexible gas barrier applications. Graphene has been...

  18. Determination of the paraxial focal length using Zernike polynomials over different apertures

    Science.gov (United States)

    Binkele, Tobias; Hilbig, David; Henning, Thomas; Fleischmann, Friedrich

    2017-02-01

    The paraxial focal length is still the most important parameter in the design of a lens. As presented at the SPIE Optics + Photonics 2016, the measured focal length is a function of the aperture. The paraxial focal length can be found when the aperture approaches zero. In this work, we investigate the dependency of the Zernike polynomials on the aperture size with respect to 3D space. By this, conventional wavefront measurement systems that apply Zernike polynomial fitting (e.g. Shack-Hartmann-Sensor) can be used to determine the paraxial focal length, too. Since the Zernike polynomials are orthogonal over a unit circle, the aperture used in the measurement has to be normalized. By shrinking the aperture and keeping up with the normalization, the Zernike coefficients change. The relation between these changes and the paraxial focal length are investigated. The dependency of the focal length on the aperture size is derived analytically and evaluated by simulation and measurement of a strong focusing lens. The measurements are performed using experimental ray tracing and a Shack-Hartmann-Sensor. Using experimental ray tracing for the measurements, the aperture can be chosen easily. Regarding the measurements with the Shack-Hartmann- Sensor, the aperture size is fixed. Thus, the Zernike polynomials have to be adapted to use different aperture sizes by the proposed method. By doing this, the paraxial focal length can be determined from the measurements in both cases.

  19. Lightweight Solar Power for Small Satellites

    Science.gov (United States)

    Nabors, Sammy A.

    2015-01-01

    The innovation targets small satellites or CubeSats for which conventional deployable arrays are not feasible due to their size, weight and complexity. This novel solar cell array includes a thin and flexible photovoltaic cell applied to an inflatable structure to create a high surface area array for collecting solar energy in a lightweight, simple and deployable structure. The inflatable array, with its high functional surface area, eliminates the need and the mechanisms required to point the system toward the sun. The power density achievable in these small arrays is similar to that of conventional high-power deployable/pointable arrays used on large satellites or space vehicles. Although inflatable solar arrays have been previously considered by others, the arrays involved the use of traditional rigid solar cells. Researchers are currently working with thin film photovoltaics from various suppliers so that the NASA innovation is not limited to any particular solar cell technology. NASA has built prototypes and tested functionality before and after inflation. As shown in the current-voltage currents below, deployment does not damage the cell performance.

  20. The High-Resolution Lightweight Telescope for the EUV (HiLiTE)

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Galarce, D S; Boerner, P; Soufli, R; De Pontieu, B; Katz, N; Title, A; Gullikson, E M; Robinson, J C; Baker, S L

    2008-06-02

    The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that will be made entirely of Silicon Carbide (SiC), optical substrates and metering structure alike. Using multilayer coatings, this instrument will be tuned to operate at the 465 {angstrom} Ne VII emission line, formed in solar transition region plasma at {approx}500,000 K. HiLiTE will have an aperture of 30 cm, angular resolution of {approx}0.2 arc seconds and operate at a cadence of {approx}5 seconds or less, having a mass that is about 1/4 that of one of the 20 cm aperture telescopes on the Atmospheric Imaging Assembly (AIA) instrument aboard NASA's Solar Dynamics Observatory (SDO). This new instrument technology thus serves as a path finder to a post-AIA, Explorer-class missions.

  1. EVOLUTION OF LIGHTWEIGHT WOOD COMPOSITES

    Directory of Open Access Journals (Sweden)

    Marius C. BARBU

    2016-01-01

    Full Text Available Lightweight boards and beams in the wood-based construction and furniture industry are not a new topic. The density reduction of panels using sandwich structure with light cores was confirmed by users like doors or mobile homes more than three decades ago. Today many ways to attain a lighter wooden structure are on offer, partially in industrial application. The first one is the use of light-weight wood species like balsa, lime, pine from southern hemisphere plantations etc. limited by the availability, strength properties, gluability and so on. A second one is the sandwich structure made from hard faces like thick veneer, thin plywood, particleboard or high density thin fiberboard and cores made from honeycomb paper, very light wood species or foams like the polystyrene one. A third way to produce a light structure is to reduce the core drastically, using predesigned skeletons with special shapes and connections to the faces. The engines for these developments are on the one hand the fast growing market of knockdown furniture and on the other hand the increasing costs for energy and raw materials. Additional factors that make weight saving a primary economical objective for most producers are transportation costs, easier handling and higher acceptance among the end users. Moreover, customers demand more for ergonomical solutions regarding packaging. Many patents were generated by researchers and developers for new one-stage production processes for sandwich panels with wood- and impregnated paper-based facings made from veneers, particles or fibres and a core consisting of expandable foams, particles or embedded hard skeletons. These ideas or prototypes could be integrated in existing continuous pressing lines for wood based panels keeping some of the advantages of the continuous production technique in matters of efficiency. Some of the challenges of the light weight wooden structure are the connection in half or final parts, resistance to

  2. Lightweight Composite Materials for Heavy Duty Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Pruez, Jacky; Shoukry, Samir; Williams, Gergis; Shoukry, Mark

    2013-08-31

    The main objective of this project is to develop, analyze and validate data, methodologies and tools that support widespread applications of automotive lightweighting technologies. Two underlying principles are guiding the research efforts towards this objective: • Seamless integration between the lightweight materials selected for certain vehicle systems, cost-effective methods for their design and manufacturing, and practical means to enhance their durability while reducing their Life-Cycle-Costs (LCC). • Smooth migration of the experience and findings accumulated so far at WVU in the areas of designing with lightweight materials, innovative joining concepts and durability predictions, from applications to the area of weight savings for heavy vehicle systems and hydrogen storage tanks, to lightweighting applications of selected systems or assemblies in light–duty vehicles.

  3. Volume changes in unrestrained structural lightweight concrete.

    Science.gov (United States)

    1964-08-01

    In this study a comparator-type measuring system was developed to accurately determine volume change characteristics of one structural lightweight concrete. The specific properties studied were the coefficient of linear thermal expansion and unrestra...

  4. 3D-printed lightweight drones

    DEFF Research Database (Denmark)

    Geiger, Raphael

    2018-01-01

    New Materials within additive manufacturing offer new potentials for drone production - especially in lightweight design. Flying drones benefit significantly from this developments. In regards to quality assurance the technical challenge is to offer a complete quality control within production. T...

  5. Vibro-acoustics of lightweight sandwich structures

    CERN Document Server

    Lu, Tianjian

    2014-01-01

    Vibro-Acoustics of Lightweight Sandwich Structures introduces the study of the coupled vibration and acoustic behavior of lightweight sandwich structures in response to harmonic force and sound pressure. This book focuses on the theoretical modeling and experimental investigation of lightweight sandwich structures in order to provide a predictive framework for vibro-acoustic characteristics of typical engineering structures. Furthermore, by developing solution tools, it concentrates on the influence of key systematic parameters leading to effective guidance for optimal structure design toward lightweight, high-stiffness and superior sound insulation capability. This book is intended for researchers, scientists, engineers and graduate students in mechanical engineering especially in structural mechanics, mechanics and acoustics. Fengxian Xin and Tianjian Lu both work at the School of Aerospace, Xi’an Jiaotong University.

  6. Cryptanalysis of Some Lightweight Symmetric Ciphers

    DEFF Research Database (Denmark)

    Abdelraheem, Mohamed Ahmed Awadelkareem Mohamed Ahmed

    In recent years, the need for lightweight encryption systems has been increasing as many applications use RFID and sensor networks which have a very low computational power and thus incapable of performing standard cryptographic operations. In response to this problem, the cryptographic community...... on a variant of PRESENT with identical round keys. We propose a new attack named the Invariant Subspace Attack that was specifically mounted against the lightweight block cipher PRINTcipher. Furthermore, we mount several attacks on a recently proposed stream cipher called A2U2....... of the international standards in lightweight cryptography. This thesis aims at analyzing and evaluating the security of some the recently proposed lightweight symmetric ciphers with a focus on PRESENT-like ciphers, namely, the block cipher PRESENT and the block cipher PRINTcipher. We provide an approach to estimate...

  7. High-contrast imaging with an arbitrary aperture: Active compensation of aperture discontinuities

    International Nuclear Information System (INIS)

    Pueyo, Laurent; Norman, Colin

    2013-01-01

    We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential deformable mirrors (DMs) to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of DM surfaces that yield high-contrast point-spread functions is not linear, and nonlinear methods are needed to find the true minimum in the optimization topology. We solve the highly nonlinear Monge-Ampere equation that is the fundamental equation describing the physics of phase-induced amplitude modulation. We determine the optimum configuration for our two sequential DM system and show that high-throughput and high-contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to the James Webb Space Telescope, ACAD can attain at least 10 –7 in contrast and an order of magnitude higher for both the future extremely large telescopes and on-axis architectures reminiscent of the Hubble Space Telescope. We show that the converging nonlinear mappings resulting from our DM shapes actually damp near-field diffraction artifacts in the vicinity of the discontinuities. Thus, ACAD actually lowers the chromatic ringing due to diffraction by segment gaps and struts while not amplifying the diffraction at the aperture edges beyond the Fresnel regime. This outer Fresnel ringing can be mitigated by properly designing the optical system. Consequently, ACAD is a true broadband solution to the problem of high-contrast imaging with segmented and/or on-axis apertures. We finally show that once the nonlinear solution is found, fine tuning with linear methods used in wavefront control can be applied to further contrast by another order of magnitude. Generally speaking, the

  8. A Lightweight Loudspeaker for Aircraft Communications and Active Noise Control

    Science.gov (United States)

    Warnaka, Glenn E.; Kleinle, Mark; Tsangaris, Parry; Oslac, Michael J.; Moskow, Harry J.

    1992-01-01

    A series of new, lightweight loudspeakers for use on commercial aircraft has been developed. The loudspeakers use NdFeB magnets and aluminum alloy frames to reduce the weight. The NdFeB magnet is virtually encapsulated by steel in the new speaker designs. Active noise reduction using internal loudspeakers was demonstrated to be effective in 1983. A weight, space, and cost efficient method for creating the active sound attenuating fields is to use the existing cabin loudspeakers for both communication and sound attenuation. This will require some additional loudspeaker design considerations.

  9. Lightweight energetic particle detector EPONA and its performance on Giotto

    Energy Technology Data Exchange (ETDEWEB)

    McKenna-Lawlor, S.; Kirsch, E.; Thompson, A.; O' Sullivan, D.; Wenzel, K.-P.

    1987-06-01

    A lightweight energetic particle detector system (EPONA/EPA) is described which was designed to operate in those novel environmental conditions (i) characterised by the varying solar aspect angles and temperatures pertaining during the cruise phase of the Giotto spacecraft and (ii) during the dust bombardment characterising closest approach (approx. 600 km) to the nucleus of comet Halley. Representative data, illustrating the functioning of EPONA during both the Giotto cruise phase and at comet encounter, are represented. The instrument has a wide range of applications to other space experiments where reliable plasma diagnostics are required.

  10. Compact and Light-Weight Solar Spaceflight Instrument Designs Utilizing Newly Developed Miniature Free-Standing Zone Plates: EUV Radiometer and Limb-Scanning Monochromator

    Science.gov (United States)

    Seely, J. F.; McMullin, D. R.; Bremer, J.; Chang, C.; Sakdinawat, A.; Jones, A. R.; Vest, R.

    2014-12-01

    Two solar instrument designs are presented that utilize newly developed miniature free-standing zone plates having interconnected Au opaque bars and no support membrane resulting in excellent long-term stability in space. Both instruments are based on a zone plate having 4 mm outer diameter and 1 to 2 degree field of view. The zone plate collects EUV radiation and focuses a narrow bandpass through a pinhole aperture and onto a silicon photodiode detector. As a miniature radiometer, EUV irradiance is accurately determined from the zone plate efficiency and the photodiode responsivity that are calibrated at the NIST SURF synchrotron facility. The EUV radiometer is pointed to the Sun and measures the absolute solar EUV irradiance in high time cadence suitable for solar physics and space weather applications. As a limb-scanning instrument in low earth orbit, a miniature zone-plate monochromator measures the extinction of solar EUV radiation by scattering through the upper atmosphere which is a measure of the variability of the ionosphere. Both instruments are compact and light-weight and are attractive for CubeSats and other missions where resources are extremely limited.

  11. Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando

    The main objective of this project was to continue the development of a synthetic aperture vector flow estimator. This type of estimator is capable of overcoming two of the major limitations in conventional ultrasound systems: 1) the inability to scan large region of interest with high temporal......, this thesis showed that novel information can be obtained with vector velocity methods providing quantitative estimates of blood flow and insight into the complexity of the hemodynamics dynamics. This could give the clinician a new tool in assessment and treatment of a broad range of diseases....

  12. Slit aperture technique for mammography

    International Nuclear Information System (INIS)

    Friedrich, M.

    1984-01-01

    Following a discussion of various principles used in the elimination of scatter, the prototype of a simple slit aperture mammography apparatus is described (modified Mammomat, Siemens). The main advantage of this technique compared with grid mammography is a halving of the radiation dose for identical image quality, using an identical film system. The technical requirements (heavy duty tube, new generator) are, however, considerable. If the film-screen systems currently in use are to remain the common systems for the future, then the development of a multi-lamellar slit diaphragm technique carries much promise for mammography. (orig.) [de

  13. Polarizing aperture stereoscopic cinema camera

    Science.gov (United States)

    Lipton, Lenny

    2012-07-01

    The art of stereoscopic cinematography has been held back because of the lack of a convenient way to reduce the stereo camera lenses' interaxial to less than the distance between the eyes. This article describes a unified stereoscopic camera and lens design that allows for varying the interaxial separation to small values using a unique electro-optical polarizing aperture design for imaging left and right perspective views onto a large single digital sensor, the size of the standard 35 mm frame, with the means to select left and right image information. Even with the added stereoscopic capability, the appearance of existing camera bodies will be unaltered.

  14. Low aperture magnetic elements measurements

    International Nuclear Information System (INIS)

    Aleksandrov, V.A.; Mikhajlichenko, A.A.; Parkhomchuk, V.V.; Seryj, A.A.; Shil'tsev, V.D.

    1991-01-01

    Two new methods of magnetic field measurements in low aperture elements are discussed. The first method uses thin magnetoresistive bismuth wire and the second-strained wire with AC. Principles of measuring used in the last technique are different from well known SLAC method of vibrating wire. Results of testing 0.38 T/mm quadrupole and VLEPP final focus test 3 T/mm lens are presented. Brief comparing of the lens axis determination precision of these methods is also discussed. 4 refs.; 8 figs

  15. 5cm aperture dipole studies

    International Nuclear Information System (INIS)

    McInturff, A.D.; Bossert, R.; Carson, J.; Fisk, H.E.; Hanft, R.; Kuchnir, M.; Lundy, R.; Mantech, P.; Strait, J.

    1986-01-01

    The results obtained during the evolution of the design, construction, and testing program of the design ''B'' dipole are presented here. Design ''B'' is one of the original three competing designs for the Superconducting Super Collider ''SSC'' arc dipoles. The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5 cm cold aperture. There have been fourteen 64 cm long 5 cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the ''Tevatron'' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were ''dry welding,'' a technique with the cable covered with Kapton insulation only and ''wet winding'' where the Kapton was covered with a light coat of ''B'' stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, loss per cycle, and harmonics were measured as a function of the magnitude and rate of change of the magnetic field, and helium bath temperature

  16. Hand aperture patterns in prehension.

    Science.gov (United States)

    Bongers, Raoul M; Zaal, Frank T J M; Jeannerod, Marc

    2012-06-01

    Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip. Objects (3, 5, or 7cm in diameter) were placed at 30, 60, 90, or 120cm from the hands' starting location. Usually the hand was opened gradually to a maximum immediately followed by hand closing, called the standard hand opening pattern. In the alternative opening patterns the hand opening was bumpy, or the hand aperture stayed at a plateau before closing started. Two participants in particular delayed the start of grasping with respect to start of reaching, with the delay time increasing with object distance. For larger object distances and smaller object sizes, the bumpy and plateau hand opening patterns were used more often. We tentatively concluded that the alternative hand opening patterns extended the hand opening phase, to arrive at the appropriate hand aperture at the appropriate time to close the hand for grasping the object. Variations in hand opening patterns deserve attention because this might lead to new insights into the coordination of reaching and grasping. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Hierarchical resilience with lightweight threads

    International Nuclear Information System (INIS)

    Wheeler, Kyle Bruce

    2011-01-01

    This paper proposes methodology for providing robustness and resilience for a highly threaded distributed- and shared-memory environment based on well-defined inputs and outputs to lightweight tasks. These inputs and outputs form a failure 'barrier', allowing tasks to be restarted or duplicated as necessary. These barriers must be expanded based on task behavior, such as communication between tasks, but do not prohibit any given behavior. One of the trends in high-performance computing codes seems to be a trend toward self-contained functions that mimic functional programming. Software designers are trending toward a model of software design where their core functions are specified in side-effect free or low-side-effect ways, wherein the inputs and outputs of the functions are well-defined. This provides the ability to copy the inputs to wherever they need to be - whether that's the other side of the PCI bus or the other side of the network - do work on that input using local memory, and then copy the outputs back (as needed). This design pattern is popular among new distributed threading environment designs. Such designs include the Barcelona STARS system, distributed OpenMP systems, the Habanero-C and Habanero-Java systems from Vivek Sarkar at Rice University, the HPX/ParalleX model from LSU, as well as our own Scalable Parallel Runtime effort (SPR) and the Trilinos stateless kernels. This design pattern is also shared by CUDA and several OpenMP extensions for GPU-type accelerators (e.g. the PGI OpenMP extensions).

  18. Aperture averaging in strong oceanic turbulence

    Science.gov (United States)

    Gökçe, Muhsin Caner; Baykal, Yahya

    2018-04-01

    Receiver aperture averaging technique is employed in underwater wireless optical communication (UWOC) systems to mitigate the effects of oceanic turbulence, thus to improve the system performance. The irradiance flux variance is a measure of the intensity fluctuations on a lens of the receiver aperture. Using the modified Rytov theory which uses the small-scale and large-scale spatial filters, and our previously presented expression that shows the atmospheric structure constant in terms of oceanic turbulence parameters, we evaluate the irradiance flux variance and the aperture averaging factor of a spherical wave in strong oceanic turbulence. Irradiance flux variance variations are examined versus the oceanic turbulence parameters and the receiver aperture diameter are examined in strong oceanic turbulence. Also, the effect of the receiver aperture diameter on the aperture averaging factor is presented in strong oceanic turbulence.

  19. Development of lightweight radiators for lunar based power systems

    International Nuclear Information System (INIS)

    Juhasz, A.J.; Bloomfield, H.S.

    1994-05-01

    This report discusses application of a new lightweight carbon-carbon (C-C) space radiator technology developed under the NASA Civil-Space Technology Initiative (CSTI) High Capacity Power Program to a 20 kWe lunar based power system. This system comprises a nuclear (SP-100 derivative) heat source, a Closed Brayton Cycle (CBC) power conversion unit with heat rejection by means of a plane radiator. The new radiator concept is based on a C-C composite heat pipe with integrally woven fins and a thin walled metallic liner for containment of the working fluid. Using measured areal specific mass values (1.5 kg/m2) for flat plate radiators, comparative CBC power system mass and performance calculations show significant advantages if conventional heat pipes for space radiators are replaced by the new C-C heat pipe technology

  20. Optimization of Dynamic Aperture of PEP-X Baseline Design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min-Huey; /SLAC; Cai, Yunhai; /SLAC; Nosochkov, Yuri; /SLAC

    2010-08-23

    SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-{angstrom} x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

  1. Optimization of Dynamic Aperture of PEP-X Baseline Design

    International Nuclear Information System (INIS)

    Wang, Min-Huey

    2010-01-01

    SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-(angstrom) x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

  2. Fast decoding algorithms for geometric coded apertures

    International Nuclear Information System (INIS)

    Byard, Kevin

    2015-01-01

    Fast decoding algorithms are described for the class of coded aperture designs known as geometric coded apertures which were introduced by Gourlay and Stephen. When compared to the direct decoding method, the algorithms significantly reduce the number of calculations required when performing the decoding for these apertures and hence speed up the decoding process. Experimental tests confirm the efficacy of these fast algorithms, demonstrating a speed up of approximately two to three orders of magnitude over direct decoding.

  3. Space Vehicle Valve System

    Science.gov (United States)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  4. Ion mobility spectrometer with virtual aperture grid

    Science.gov (United States)

    Pfeifer, Kent B.; Rumpf, Arthur N.

    2010-11-23

    An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.

  5. Motion measurement for synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-01-01

    Synthetic Aperture Radar (SAR) measures radar soundings from a set of locations typically along the flight path of a radar platform vehicle. Optimal focusing requires precise knowledge of the sounding source locations in 3-D space with respect to the target scene. Even data driven focusing techniques (i.e. autofocus) requires some degree of initial fidelity in the measurements of the motion of the radar. These requirements may be quite stringent especially for fine resolution, long ranges, and low velocities. The principal instrument for measuring motion is typically an Inertial Measurement Unit (IMU), but these instruments have inherent limi ted precision and accuracy. The question is %22How good does an IMU need to be for a SAR across its performance space?%22 This report analytically relates IMU specifications to parametric requirements for SAR. - 4 - Acknowledgements Th e preparation of this report is the result of a n unfunded research and development activity . Although this report is an independent effort, it draws heavily from limited - release documentation generated under a CRADA with General Atomics - Aeronautical System, Inc. (GA - ASI), and under the Joint DoD/DOE Munitions Program Memorandum of Understanding. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of En ergy's National Nuclear Security Administration under contract AC04-94AL85000.

  6. Geopolymerization of lightweight aggregate waste

    Directory of Open Access Journals (Sweden)

    Labrincha, J. A.

    2008-09-01

    Full Text Available Geopolymerization is a viable way to process and re-use alumino-silicate industrial waste while producing highstrength, high chemical inertia materials that can effectively immobilize other industrial by-products, and even hazardous waste. In this study industrial waste from different stages of the manufacture of lightweight expanded clay aggregate was characterized for its possible transformation, via alkali activation, to geopolymers. The ultimate aim was to assess the possibility of using such geopolymers to develop thermal and acoustic insulation panels. The containment of hazardous materials is another important application for these new materials. Geopolymers were prepared for this study with different particles size distributions and activator concentrations. Their mechanical properties, composition and microstructure were characterized and a material with promising insulating properties was produced. A preliminary analysis was conducted of the salt formation observed in these geopolymers, the chief drawback to their use.La geopolimerización es una manera viable para procesar y agregar valor a los residuos industriales de alumino-silicato dando lugar a materiales con elevadas resistencias mecánmicas, alta inercia química y que permiten encapsular otros residuos, incluso peligrosos. Los residuos industriales que proceden de diversos tipos de arcillas para la fabricación de áridos ligeros se han caracterizado para la producción de geopolímeros mediante el proceso de ataque alcalino. Su incorporación en una matriz geopolimérica permite la posibilidad de desarrollo de paneles de aislamiento (térmico y acústico. Además, la inmovilización de materiales peligrosos es un logro adicional importante. Los geopolímeros se han producido con fórmulas diferentes y se han caracterizado sus propiedades mecánicas, composición y microestructura, para dar lugar a una composición interesante con propiedades aislantes. Se ha llevado a cabo

  7. Parameter scans and accuracy estimates of the dynamical aperture of the CERN LHC

    CERN Document Server

    Giovannozzi, Massimo

    2006-01-01

    Techniques to make use of large distributed computing facilities allow for denser parameter scans of the dynamic aperture, i.e., the domain in phase space where bounded single-particle motion prevails. Moreover, one can also increase the number of 'seeds' each of which represents a possible realization of multipolar components around the machine. In this paper the dependence of the dynamic aperture on the step size of the grid of initial conditions and on the number of seeds is studied. Estimates on the accuracy of the dynamic aperture are derived and the definition of an improved protocol for numerical simulations is presented.

  8. Lightweight Gearbox Technology, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — To date, the majority of the gearboxes used on the rovers have been based on very conventional materials, process and designs. This has primarily been a result of...

  9. Modular Orbital Demonstration of an Evolvable Space Telescope (MODEST)

    Science.gov (United States)

    Baldauf, Brian; Conti, Alberto

    2016-01-01

    The "Search for Life" via imaging of exoplanets is a mission that requires extremely stable telescopes with apertures in the 10 m to 20 m range. The High Definition Space Telescope (HDST) envisioned for this mission would have an aperture >10 m, which is a larger payload than what can be delivered to space using a single launch vehicle. Building and assembling the mirror segments enabling large telescopes will likely require multiple launches and assembly in space. Space-based telescopes with large apertures will require major changes to system architectures.The Optical Telescope Assembly (OTA) for HDST is a primary mission cost driver. Enabling and affordable solutions for this next generation of large aperture space-based telescope are needed.This paper reports on the concept for the Modular Orbital Demonstration of an Evolvable Space Telescope (MODEST), which demonstrates on-orbit robotic and/or astronaut assembly of a precision optical telescope in space. It will also facilitate demonstration of active correction of phase and mirror shape. MODEST is proposed to be delivered to the ISS using standard Express Logistics Carriers (ELCs) and can mounted to one of a variety of ISS pallets. Post-assembly value includes space, ground, and environmental studies, and a testbed for new instruments. This demonstration program for next generation mirror technology provides significant risk reduction and demonstrates the technology in a six-mirror phased telescope. Other key features of the demonstration include the use of an active primary optical surface with wavefront feedback control that allows on-orbit optimization and demonstration of precise surface control to meet optical system wavefront and stability requirements.MODEST will also be used to evaluate advances in lightweight mirror and metering structure materials such as SiC or Carbon Fiber Reinforced Polymer that have excellent mechanical and thermal properties, e.g. high stiffness, high modulus, high thermal

  10. Performance of lightweight large C/SiC mirror

    Science.gov (United States)

    Yui, Yukari Y.; Goto, Ken; Kaneda, Hidehiro; Katayama, Haruyoshi; Kotani, Masaki; Miyamoto, Masashi; Naitoh, Masataka; Nakagawa, Takao; Saruwatari, Hideki; Suganuma, Masahiro; Sugita, Hiroyuki; Tange, Yoshio; Utsunomiya, Shin; Yamamoto, Yasuji; Yamawaki, Toshihiko

    2017-11-01

    Very lightweight mirror will be required in the near future for both astronomical and earth science/observation missions. Silicon carbide is becoming one of the major materials applied especially to large and/or light space-borne optics, such as Herschel, GAIA, and SPICA. On the other hand, the technology of highly accurate optical measurement of large telescopes, especially in visible wavelength or cryogenic circumstances is also indispensable to realize such space-borne telescopes and hence the successful missions. We have manufactured a very lightweight Φ=800mm mirror made of carbon reinforced silicon carbide composite that can be used to evaluate the homogeneity of the mirror substrate and to master and establish the ground testing method and techniques by assembling it as the primary mirror into an optical system. All other parts of the optics model are also made of the same material as the primary mirror. The composite material was assumed to be homogeneous from the mechanical tests of samples cut out from the various areas of the 800mm mirror green-body and the cryogenic optical measurement of the mirror surface deformation of a 160mm sample mirror that is also made from the same green-body as the 800mm mirror. The circumstance and condition of the optical testing facility has been confirmed to be capable for the highly precise optical measurements of large optical systems of horizontal light axis configuration. Stitching measurement method and the algorithm for analysis of the measurement is also under study.

  11. The Design of a Lightweight RFID Middleware

    Directory of Open Access Journals (Sweden)

    Fengqun Lin

    2009-10-01

    Full Text Available Radio Frequency Identification (RFID middleware is often regarded as the central nervous system of RFID systems. In this paper, a lightweight RFID middleware is designed and implemented without the need of an Application Level Events (ALE structure, and its implementation process is described using a typical commerical enterprise. A short review of the current RFID middleware research and development is also included. The characteristics of RFID middleware are presented with a two-centric framework. The senarios of RFID data integration based on the simplified structure are provided to illuminats the design and implementation of the lightweight middleware structure and its development process. The lightweight middleware is easy to maintain and extend because of the simplified and streamlined structure and the short development cycle.

  12. Lightweight Cryptography for Passive RFID Tags

    DEFF Research Database (Denmark)

    David, Mathieu

    2012-01-01

    were mostly unsatisfactory. As a conclusion, a new branch of cryptography, commonly called Lightweight Cryptography, emerged to address the issues of these tiny ubiquitous devices. This Thesis presents a comprehensive engineering to lightweight cryptography, proposes a classification and explores its...... various ramifications by giving key examples in each of them. We select two of these branches, ultralightweight cryptography and symmetric-key cryptography, and propose a cryptographic primitive in each of them. In the case of symmetric-key cryptography, we propose a stream cipher that has a footprint...... of an integrator for a particular application. Finally, we conclude that the research for finding robust cryptographic primitive in the branch of lightweight cryptography still has some nice days ahead, and that providing a secure cryptosystem for printed electronics RFID tags remains an open research topic....

  13. Infinte Periodic Structure of Lightweight Elements

    DEFF Research Database (Denmark)

    Domadiya, Parthkumar Gandalal; Andersen, Lars Vabbersgaard; Sorokin, Sergey

    2013-01-01

    Lightweight wooden structures have become more popular as a sustainable, environmental- friendly and cost-effective alternative to concrete, steel and masonry buildings. However, there are certain drawbacks regarding noise and vibration due to the smaller weight and stiffness of wooden buildings....... Furthermore, lightweight building elements are typically periodic structures that behave as filters for sound propagation within certain frequency ranges (stop bands), thus only allowing transmission within the pass bands. Hence, traditional methods based on statistical energy analysis cannot be used...... for proper dynamic assessment of lightweight buildings. Instead, this paper discusses and compares the use of finite element analysis and a wave approach based on Floquet theory. The present analysis has focus on the effect of periodicity on vibration transmission within semi-infinite beam structures. Two...

  14. LIGHT-WEIGHT LOAD-BEARING STRUCTURE

    DEFF Research Database (Denmark)

    2009-01-01

    The invention relates to a light-weight load-bearing structure (1) with optimized compression zone (2), where along one or more compression zones (2) in the structure (1) to be cast a core (3) of strong concrete is provided, which core (3) is surrounded by concrete of less strength (4) compared...... to the core (3) of strong concrete. The invention also relates to a method of casting of light-weight load-bearing structures (1) with optimized compression zone (2) where one or more channels, grooves, ducts, pipes and/or hoses (5) formed in the load-bearing structure (1) serves as moulds for moulding one...... or more cores (3) of strong concrete in the light-weight load-bearing structure (1)....

  15. Application of Ruze Equation for Inflatable Aperture Antennas

    Science.gov (United States)

    Welch, Bryan W.

    2008-01-01

    Inflatable aperture reflector antennas are an emerging technology that NASA is investigating for potential uses in science and exploration missions. As inflatable aperture antennas have not been proven fully qualified for space missions, they must be characterized properly so that the behavior of the antennas can be known in advance. To properly characterize the inflatable aperture antenna, testing must be performed in a relevant environment, such as a vacuum chamber. Since the capability of having a radiofrequency (RF) test facility inside a vacuum chamber did not exist at NASA Glenn Research Center, a different methodology had to be utilized. The proposal to test an inflatable aperture antenna in a vacuum chamber entailed performing a photogrammetry study of the antenna surface by using laser ranging measurements. A root-mean-square (rms) error term was derived from the photogrammetry study to calculate the antenna surface loss as described by the Ruze equation. However, initial testing showed that problems existed in using the Ruze equation to calculate the loss due to errors on the antenna surface. This study utilized RF measurements obtained in a near-field antenna range and photogrammetry data taken from a laser range scanner to compare the expected performance of the test antenna (via the Ruze equation) with the actual RF patterns and directivity measurements. Results showed that the Ruze equation overstated the degradation in the directivity calculation. Therefore, when the photogrammetry study is performed on the test antennas in the vacuum chamber, a more complex equation must be used in light of the fact that the Ruze theory overstates the loss in directivity for inflatable aperture reflector antennas.

  16. Synthetic aperture radar: principles and applications

    International Nuclear Information System (INIS)

    Khan, N.A.; Yahya, K.M.

    2003-01-01

    In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information. (author)

  17. A MAC Mode for Lightweight Block Ciphers

    DEFF Research Database (Denmark)

    Luykx, Atul; Preneel, Bart; Tischhauser, Elmar Wolfgang

    2016-01-01

    Lightweight cryptography strives to protect communication in constrained environments without sacrificing security. However, security often conflicts with efficiency, shown by the fact that many new lightweight block cipher designs have block sizes as low as 64 or 32 bits. Such low block sizes lead...... no effect on the security bound, allowing an order of magnitude more data to be processed per key. Furthermore, LightMAC is incredibly simple, has almost no overhead over the block cipher, and is parallelizable. As a result, LightMAC not only offers compact authentication for resource-constrained platforms...

  18. Cases of Lightweight Structures for Polar Areas

    DEFF Research Database (Denmark)

    Pedreros, Jessica Fernandoy; Christ, Julian; Shepherd, Paul

    2017-01-01

    The paper focuses on what the authors call ‘Polar Lightweight Structures’. The first part presents a collection of lightweight structures (LWS) designed and built for Antarctic conditions, with the aim of demonstrating the diversity of approaches attempted by designers. The second part of the paper...... presents two studies where different computational methods were applied for the design of generic LWS based on the local conditions of two particular Polar locations; namely, the Arctic region and Glacier Union in the Antarctic plateau. Both studies were conducted independently with the aim...

  19. Environmental assessment of lightweight electric vehicles

    CERN Document Server

    Egede, Patricia

    2017-01-01

    This monograph adresses the challenge of the environmental assessment of leightweight electric vehicles. It poses the question whether the use of lightweight materials in electric vehicles can reduce the vehicles’ environmental impact and compares the environmental performance of a lightweight electric vehicle (LEV) to other types of vehicles. The topical approach focuses on methods from life cycle assessment (LCA), and the book concludes with a comprehensive concept on the environmental assessment of LEVs. The target audience primarily comprises LCA practitioners from research institutes and industry, but it may also be beneficial for graduate students specializing in the field of environmental assessment.

  20. Southern Regional Center for Lightweight Innovative Design

    Energy Technology Data Exchange (ETDEWEB)

    Horstemeyer, Mark F. [Mississippi State Univ., Mississippi State, MS (United States); Wang, Paul [Mississippi State Univ., Mississippi State, MS (United States)

    2011-12-27

    The three major objectives of this Phase III project are: To develop experimentally validated cradle-to-grave modeling and simulation tools to optimize automotive and truck components for lightweighting materials (aluminum, steel, and Mg alloys and polymer-based composites) with consideration of uncertainty to decrease weight and cost, yet increase the performance and safety in impact scenarios; To develop multiscale computational models that quantify microstructure-property relations by evaluating various length scales, from the atomic through component levels, for each step of the manufacturing process for vehicles; and To develop an integrated K-12 educational program to educate students on lightweighting designs and impact scenarios.

  1. High-Pressure Lightweight Thrusters

    Science.gov (United States)

    Holmes, Richard; McKechnie, Timothy; Shchetkovskiy, Anatoliy; Smirnov, Alexander

    2013-01-01

    Returning samples of Martian soil and rock to Earth is of great interest to scientists. There were numerous studies to evaluate Mars Sample Return (MSR) mission architectures, technology needs, development plans, and requirements. The largest propulsion risk element of the MSR mission is the Mars Ascent Vehicle (MAV). Along with the baseline solid-propellant vehicle, liquid propellants have been considered. Similar requirements apply to other lander ascent engines and reaction control systems. The performance of current state-ofthe- art liquid propellant engines can be significantly improved by increasing both combustion temperature and pressure. Pump-fed propulsion is suggested for a single-stage bipropellant MAV. Achieving a 90-percent stage propellant fraction is thought to be possible on a 100-kg scale, including sufficient thrust for lifting off Mars. To increase the performance of storable bipropellant rocket engines, a high-pressure, lightweight combustion chamber was designed. Iridium liner electrodeposition was investigated on complex-shaped thrust chamber mandrels. Dense, uniform iridium liners were produced on chamber and cylindrical mandrels. Carbon/carbon composite (C/C) structures were braided over iridium-lined mandrels and densified by chemical vapor infiltration. Niobium deposition was evaluated for forming a metallic attachment flange on the carbon/ carbon structure. The new thrust chamber was designed to exceed state-of-the-art performance, and was manufactured with an 83-percent weight savings. High-performance C/Cs possess a unique set of properties that make them desirable materials for high-temperature structures used in rocket propulsion components, hypersonic vehicles, and aircraft brakes. In particular, more attention is focused on 3D braided C/Cs due to their mesh-work structure. Research on the properties of C/Cs has shown that the strength of composites is strongly affected by the fiber-matrix interfacial bonding, and that weakening

  2. Portable and Lightweight Ramp Structure

    Science.gov (United States)

    2001-04-09

    long side of which is in abutting relationship with the 12 short side of the end of the ramp. Fastener receivers are equi- 13 spaced in duplicate...The modular sections are conveniently prefabricated 18 1 and provided in kit form to the number of sections corresponding 2 to the desired ramp

  3. Large-Aperture Membrane Active Phased-Array Antennas

    Science.gov (United States)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  4. Pavement evaluation using a portable lightweight deflectometer.

    Science.gov (United States)

    2012-12-01

    The use of Zorn ZFG-3000 portable Lightweight Deflectometer (LWD) in the in-situ : assessment of pavement quality was investigated in this research. A lower load and a : shorter load pulse duration are used in a LWD as compared to a Falling Weight : ...

  5. Compact, Lightweight Servo-Controllable Brakes

    Science.gov (United States)

    Lovchik, Christopher S.; Townsend, William; Guertin, Jeffrey; Matsuoka, Yoky

    2010-01-01

    Compact, lightweight servo-controllable brakes capable of high torques are being developed for incorporation into robot joints. A brake of this type is based partly on the capstan effect of tension elements. In a brake of the type under development, a controllable intermediate state of torque is reached through on/off switching at a high frequency.

  6. FY 2012 Lightweight Materials Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-04-15

    The FY 2012 Annual Progress Report for Lightweight Materials provides a detailed description of the activities and technical accomplishments which focuses on the development and validation of advanced materials and manufacturing technologies to significantly reduce light and heavy duty vehicle weight without compromising other attributes such as safety, performance, recyclability, and cost.

  7. FY2015 Lightweight Materials R&D Annual Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2016-09-30

    The Lightweight Materials research and development (R&D) area within the DOE Vehicle Technologies Office (VTO) provides support and guidance for many cutting-edge automotive technologies under development. Research focuses on addressing critical barriers to commercializing lightweight materials for passenger and commercial vehicles. This report describes the progress made on the research and development projects funded by the Lightweight Materials area.

  8. Silicon Carbide Corrugated Mirrors for Space Telescopes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Trex Enterprises Corporation (Trex) proposes technology development to manufacture monolithic, lightweight silicon carbide corrugated mirrors (SCCM) suitable for...

  9. Lightweight, high-frequency transformers

    Science.gov (United States)

    Schwarze, G. E.

    1983-01-01

    The 25-kVA space transformer was developed under contract by Thermal Technology Laboratory, Buffalo, N. Y. The NASA Lewis transformer technology program attempted to develop the baseline technology. For the 25-kVA transformer the input voltage was chosen as 200 V, the output voltage as 1500 V, the input voltage waveform as square wave, the duty cycle as continuous, the frequency range (within certain constraints) as 10 to 40 kHz, the operating temperatures as 85 deg. and 130 C, the baseplate temperature as 50 C, the equivalent leakage inductance as less than 10 micro-h, the operating environment as space, and the life expectancy as 10 years. Such a transformer can also be used for aircraft, ship and terrestrial applications.

  10. Vehicle Lightweighting: 40% and 45% Weight Savings Analysis: Technical Cost Modeling for Vehicle Lightweighting

    Energy Technology Data Exchange (ETDEWEB)

    Mascarin, Anthony [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hannibal, Ted [Idaho National Lab. (INL), Idaho Falls, ID (United States); Raghunathan, Anand [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ivanic, Ziga [Idaho National Lab. (INL), Idaho Falls, ID (United States); Francfort, James [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-04-01

    The U.S. Department of Energy’s Vehicle Technologies Office, Materials area commissioned a study to model and assess manufacturing economics of alternative design and production strategies for a series of lightweight vehicle concepts. The strategic targets were a 40% and a 45% mass reduction relative to a standard North American midsize passenger sedan at an effective cost of $3.42 per pound (lb) saved. The baseline vehicle was an average of several available vehicles in this class. Mass and cost breakdowns from several sources were used, including original equipment manufacturers’ (OEMs’) input through U.S. Department of Energy’s Vehicle Technologies Office programs and public presentations, A2Mac1 LLC’s teardown information, Lotus Engineering Limited and FEV, Inc. breakdowns in their respective lightweighting studies, and IBIS Associates, Inc.’s decades of experience in automotive lightweighting and materials substitution analyses. Information on lightweighting strategies in this analysis came from these same sources and the ongoing U.S. Department of Energy-funded Vehma International of America, Inc. /Ford Motor Company Multi-Material Lightweight Prototype Vehicle Demonstration Project, the Aluminum Association Transportation Group, and many United States Council for Automotive Research’s/United States Automotive Materials Partnership LLC lightweight materials programs.

  11. Integrated High-Speed Digital Optical True-Time-Delay Modules for Synthetic Aperture Radars, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Crystal Research, Inc. proposes an integrated high-speed digital optical true-time-delay module for advanced synthetic aperture radars. The unique feature of this...

  12. SUPERPOLISHED SI COATED SIC OPTICS FOR RAPID MANUFACTURE OF LARGE APERTURE UV AND EUV TELESCOPES, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — SSG/Tinsley proposes an innovative optical manufacturing process that will allow the advancement of state-of-the-art Silicon Carbide (SiC) mirrors for large aperture...

  13. Aperture meter for the Large Hadron Collider

    International Nuclear Information System (INIS)

    Mueller, G.J.; Fuchsberger, K.; Redaelli, S.

    2012-01-01

    The control of the high intensity beams of the CERN Large Hadron Collider (LHC) is particular challenging and requires a good modeling of the machine and monitoring of various machine parameters. During operation it is crucial to ensure a minimal distance between the beam edge and the aperture of sensitive equipment, e.g. the superconducting magnets, which in all cases must be in the shadow of the collimator's that protect the machine. Possible dangerous situations must be detected as soon as possible. In order to provide the operator with information about the current machine bottlenecks an aperture meter application was developed based on the LHC online modeling tool-chain. The calculation of available free aperture takes into account the best available optics and aperture model as well as the relevant beam measurements. This paper describes the design and integration of this application into the control environment and presents results of the usage in daily operation and from validation measurements. (authors)

  14. A Lightweight, User-controlled System For The Home

    Directory of Open Access Journals (Sweden)

    Lynne Baillie

    2006-01-01

    Full Text Available This paper explores how we designed, with input from some elderly persons, a multi-agent user-controlled network for the home. The system was designed to support the elderly in living longer at home with minimal support. We describe how our work attempts to tackle issues such as privacy, control of personal space, and enjoyment within the home. As the number of elderly individuals’ increases, a certain amount of information gathering or support may be required to assist the elderly in their homes. However, we strongly believe that we should preserve people’s privacy in their homes and ensure that any artifact we propose is seen as enjoyable, aesthetically pleasing and, most importantly, not stigmatizing. We describe in this paper how a lightweight setup, using a multimodal mobile robot, a PDA, and an interactive television, can assist the elderly in the home in an enjoyable and unobtrusive way.

  15. An Ultra-Lightweight Encryption Scheme in Underwater Acoustic Networks

    Directory of Open Access Journals (Sweden)

    Chunyan Peng

    2016-01-01

    Full Text Available We tackle a fundamental security problem in underwater acoustic networks (UANs. The S-box in the existing block encryption algorithm is more energy consuming and unsuitable for resources-constrained UANs. In this paper, instead of S-box, we present a lightweight, 8-round iteration block cipher algorithm for UANs communication based on chaotic theory and increase the key space by changing the number of iteration round. We further propose secure network architecture of UANs. By analysis, our algorithm can resist brute-force searches and adversarial attacks. Simulation results show that, compared with traditional AES-128 and PRESENT algorithms, our cryptographic algorithm can make a good trade-off between security and overhead, has better energy efficiency, and applies to UANs.

  16. Programmable Ultra-Lightweight System Adaptable Radio Satellite Base Station

    Science.gov (United States)

    Varnavas, Kosta; Sims, Herb

    2015-01-01

    With the explosion of the CubeSat, small sat, and nanosat markets, the need for a robust, highly capable, yet affordable satellite base station, capable of telemetry capture and relay, is significant. The Programmable Ultra-Lightweight System Adaptable Radio (PULSAR) is NASA Marshall Space Flight Center's (MSFC's) software-defined digital radio, developed with previous Technology Investment Programs and Technology Transfer Office resources. The current PULSAR will have achieved a Technology Readiness Level-6 by the end of FY 2014. The extensibility of the PULSAR will allow it to be adapted to perform the tasks of a mobile base station capable of commanding, receiving, and processing satellite, rover, or planetary probe data streams with an appropriate antenna.

  17. Chinese very small aperture terminal system for ministries

    Science.gov (United States)

    Dan, Sen

    The objective and technologic approach of the Chinese very small aperture terminal (VSAT) system of data communications is described in this paper. The system is primarily designed for the management business of many governmental ministries and administrations. It consists of a centralized processing and switching facility and a number of groups of remote terminals. The network is constructed in a star configuration because of simplicity and the inherent nature of the management business. Either Intelsat of Chinese domestic communications satellite can be used for the space segment. The system performance has been verified by field trials. Some results of system analysis can be used for traffic design.

  18. Monitoring coastal inundation with Synthetic Aperture Radar satellite data

    Science.gov (United States)

    Suzuoki, Yukihiro; Rangoonwala, Amina; Ramsey, Elijah W.

    2011-01-01

    Maps representing the presence and absence of surface inundation in the Louisiana coastal zone were created from available satellite scenes acquired by the Japanese Aerospace Exploration Agency's Advanced Land Observing Satellite and by the European Space Agency's Envisat from late 2006 through summer 2009. Detection of aboveground surface flooding relied on the well-documented and distinct signature of decreased backscatter in Synthetic Aperture Radar (SAR), which is indicative of inundated marsh in the Gulf of Mexico. Even though decreases in backscatter were distinctive, the multiplicity of possible interactions between changing flood depths and canopy height yielded complex SAR-based representations of the marshes.

  19. Southern Regional Center for Lightweight Innovative Design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Paul T. [Mississippi State Univ., Mississippi State, MS (United States)

    2012-12-01

    The Southern Regional Center for Lightweight Innovative Design (SRCLID) has developed an experimentally validated cradle-to-grave modeling and simulation effort to optimize automotive components in order to decrease weight and cost, yet increase performance and safety in crash scenarios. In summary, the three major objectives of this project are accomplished: To develop experimentally validated cradle-to-grave modeling and simulation tools to optimize automotive and truck components for lightweighting materials (aluminum, steel, and Mg alloys and polymer-based composites) with consideration of uncertainty to decrease weight and cost, yet increase the performance and safety in impact scenarios; To develop multiscale computational models that quantify microstructure-property relations by evaluating various length scales, from the atomic through component levels, for each step of the manufacturing process for vehicles; and To develop an integrated K-12 educational program to educate students on lightweighting designs and impact scenarios. In this final report, we divided the content into two parts: the first part contains the development of building blocks for the project, including materials and process models, process-structure-property (PSP) relationship, and experimental validation capabilities; the second part presents the demonstration task for Mg front-end work associated with USAMP projects.

  20. Shock Response of Lightweight Adobe Masonry

    Science.gov (United States)

    Sauer, C.; Bagusat, F.; Heine, A.; Riedel, W.

    2018-04-01

    The behavior of a low density and low-strength building material under shock loading is investigated. The considered material is lightweight adobe masonry characterized by a density of 1.2 g/cm3 and a quasi-static uniaxial compressive strength of 2.8 MPa. Planar-plate-impact (PPI) tests with velocities in between 295 and 950 m/s are performed in order to obtain Hugoniot data and to derive parameters for an equation of state (EOS) that captures the occurring phenomenology of porous compaction and subsequent unloading. The resulting EOS description is validated by comparing the experimental free surface velocity time curves with those obtained by numerical simulations of the performed PPI tests. The non-linear compression behavior, including the pore compaction mechanism, constitutes a main ingredient for modelling the response of adobe to blast and high-velocity impact loading. We hence present a modeling approach for lightweight adobe which can be applied to such high rate loading scenarios in future studies. In general, this work shows that PPI tests on lightweight and low-strength geological materials can be used to extract Hugoniot data despite significant material inhomogeneity. Furthermore, we demonstrate that a homogenous material model is able to numerically describe such a material under shock compression and release with a reasonable accuracy.

  1. Innovative lightweight substrate for stable optical benches and mirrors

    Science.gov (United States)

    Rugi Grond, E.; Herren, A.; Mérillat, S.; Fermé, J. J.

    2017-11-01

    High precision space optics, such as spectrometers, relay optics, and filters, require ultra stable, lightweight platforms. These equipped platforms have on one side to survive the launch loads, on the other side they have to maintain their stability also under the varying thermal loads occurring in space. Typically such platforms have their equipment (prisms, etalons, beam expanders, etc.) mounted by means of classical bonding, hydro-catalytic bonding or optical contacting. Therefore such an optical bench requires to provide an excellent flatness, minimal roughness and is usually made of the same material as the equipment it carries (glass, glass ceramics). For space systems, mass is a big penalty, therefore such optical platforms are in most cases light weighted by means of machining features (i.e. pockets). Besides of being not extremely mass efficient, such pockets reduce the load carrying capability of the base material significantly. The challenge for Oerlikon Space, in this context, was to develop, qualify and deliver such optical benches, providing a substantial mass reduction compared to actual light weighted systems, while maintaining most of the full load carrying capacity of the base material. Additionally such a substrate can find an attractive application for mirror substrates. The results of the first development and of the first test results will be presented.

  2. Calibration of the TUD Ku-band Synthetic Aperture Radiometer

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1995-01-01

    The TUD Synthetic Aperture Radiometer is a 2-channel demonstration model that can simulate a thinned aperture radiometer having an unfilled aperture consisting of several small antenna elements. Aperture synthesis obtained by interferometric measurements using the antenna elements in pairs, follo...

  3. Design of the polar neutron-imaging aperture for use at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Fatherley, V. E., E-mail: vef@lanl.gov; Martinez, J. I.; Merrill, F. E.; Oertel, J. A.; Schmidt, D. W.; Volegov, P. L.; Wilde, C. H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barker, D. A.; Fittinghoff, D. N.; Hibbard, R. L. [Lawrence Livermore National Laboratory, Livermore, California 94551-0808 (United States)

    2016-11-15

    The installation of a neutron imaging diagnostic with a polar view at the National Ignition Facility (NIF) required design of a new aperture, an extended pinhole array (PHA). This PHA is different from the pinhole array for the existing equatorial system due to significant changes in the alignment and recording systems. The complex set of component requirements, as well as significant space constraints in its intended location, makes the design of this aperture challenging. In addition, lessons learned from development of prior apertures mandate careful aperture metrology prior to first use. This paper discusses the PHA requirements, constraints, and the final design. The PHA design is complex due to size constraints, machining precision, assembly tolerances, and design requirements. When fully assembled, the aperture is a 15 mm × 15 mm × 200 mm tungsten and gold assembly. The PHA body is made from 2 layers of tungsten and 11 layers of gold. The gold layers include 4 layers containing penumbral openings, 4 layers containing pinholes and 3 spacer layers. In total, there are 64 individual, triangular pinholes with a field of view (FOV) of 200 μm and 6 penumbral apertures. Each pinhole is pointed to a slightly different location in the target plane, making the effective FOV of this PHA a 700 μm square in the target plane. The large FOV of the PHA reduces the alignment requirements both for the PHA and the target, allowing for alignment with a laser tracking system at NIF.

  4. Effects of surface-mapping corrections and synthetic-aperture focusing techniques on ultrasonic imaging

    International Nuclear Information System (INIS)

    Barna, B.A.; Johnson, J.A.

    1981-01-01

    Improvements in ultrasonic imaging that can be obtained using algorithms that map the surface of targets are evaluated. This information is incorporated in the application of synthetic-aperture focusing techniques which also have the potential to improve image resolution. Images obtained using directed-beam (flat) transducers and the focused transducers normally used for synthetic-aperture processing are quantitatively compared by using no processing, synthetic-aperture processing with no corrections for surface variations, and synthetic-aperture processing with surface mapping. The unprocessed images have relatively poor lateral resolutions because echoes from two adjacent reflectors show interference effects which prevent their identification even if the spacing is larger than the single-hole resolution. The synthetic-aperture-processed images show at least a twofold improvement in lateral resolution and greatly reduced interference effects in multiple-hole images compared to directed-beam images. Perhaps more importantly, in images of test blocks with substantial surface variations portions of the image are displaced from their actual positions by several wavelengths. To correct for this effect an algorithm has been developed for calculating the surface variations. The corrected images produced using this algorithm are accurate within the experimental error. In addition, the same algorithm, when applied to the directed-beam data, produced images that are not only accurately positioned, but that also have a resolution comparable to conventional synthetic-aperture-processed images obtained from focused-transducer data. This suggests that using synthetic-aperture processing on the type of data normally collected during directed-beam ultrasonic inspections would eliminate the need to rescan for synthetic-aperture enhancement

  5. Sensor-Oriented Path Planning for Multiregion Surveillance with a Single Lightweight UAV SAR.

    Science.gov (United States)

    Li, Jincheng; Chen, Jie; Wang, Pengbo; Li, Chunsheng

    2018-02-11

    In the surveillance of interested regions by unmanned aerial vehicle (UAV), system performance relies greatly on the motion control strategy of the UAV and the operation characteristics of the onboard sensors. This paper investigates the 2D path planning problem for the lightweight UAV synthetic aperture radar (SAR) system in an environment of multiple regions of interest (ROIs), the sizes of which are comparable to the radar swath width. Taking into account the special requirements of the SAR system on the motion of the platform, we model path planning for UAV SAR as a constrained multiobjective optimization problem (MOP). Based on the fact that the UAV route can be designed in the map image, an image-based path planner is proposed in this paper. First, the neighboring ROIs are merged by the morphological operation. Then, the parts of routes for data collection of the ROIs can be located according to the geometric features of the ROIs and the observation geometry of UAV SAR. Lastly, the route segments for ROIs surveillance are connected by a path planning algorithm named the sampling-based sparse A* search (SSAS) algorithm. Simulation experiments in real scenarios demonstrate that the proposed sensor-oriented path planner can improve the reconnaissance performance of lightweight UAV SAR greatly compared with the conventional zigzag path planner.

  6. Sensor-Oriented Path Planning for Multiregion Surveillance with a Single Lightweight UAV SAR

    Science.gov (United States)

    Li, Jincheng; Chen, Jie; Wang, Pengbo; Li, Chunsheng

    2018-01-01

    In the surveillance of interested regions by unmanned aerial vehicle (UAV), system performance relies greatly on the motion control strategy of the UAV and the operation characteristics of the onboard sensors. This paper investigates the 2D path planning problem for the lightweight UAV synthetic aperture radar (SAR) system in an environment of multiple regions of interest (ROIs), the sizes of which are comparable to the radar swath width. Taking into account the special requirements of the SAR system on the motion of the platform, we model path planning for UAV SAR as a constrained multiobjective optimization problem (MOP). Based on the fact that the UAV route can be designed in the map image, an image-based path planner is proposed in this paper. First, the neighboring ROIs are merged by the morphological operation. Then, the parts of routes for data collection of the ROIs can be located according to the geometric features of the ROIs and the observation geometry of UAV SAR. Lastly, the route segments for ROIs surveillance are connected by a path planning algorithm named the sampling-based sparse A* search (SSAS) algorithm. Simulation experiments in real scenarios demonstrate that the proposed sensor-oriented path planner can improve the reconnaissance performance of lightweight UAV SAR greatly compared with the conventional zigzag path planner. PMID:29439447

  7. Experimental study on microstructure characters of foamed lightweight soil

    Science.gov (United States)

    Qiu, Youqiang; Li, Yongliang; Li, Meixia; Liu, Yaofu; Zhang, Liujun

    2018-01-01

    In order to verify the microstructure of foamed lightweight soil and its characters of compressive strength, four foamed lightweight soil samples with different water-soild ratio were selected and the microstructure characters of these samples were scanned by electron microscope. At the same time, the characters of compressive strength of foamed lightweight soil were analyzed from the microstructure. The study results show that the water-soild ratio has a prominent effect on the microstructure and compressive strength of foamed lightweight soil, with the decrease of water-solid ratio, the amount and the perforation of pores would be reduced significantly, thus eventually forming a denser and fuller interior structure. Besides, the denser microstructure and solider pore-pore wall is benefit to greatly increase mechanical intensity of foamed lightweight soil. In addition, there are very few acicular ettringite crystals in the interior of foamed lightweight soil, its number is also reduced with the decrease in water-soild ratio.

  8. Design of ultra-lightweight concrete: towards monolithic concrete structures

    Directory of Open Access Journals (Sweden)

    Yu Qing Liang

    2014-04-01

    Full Text Available This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K; and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm . This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

  9. Lightweight and Statistical Techniques for Petascale PetaScale Debugging

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Barton

    2014-06-30

    This project investigated novel techniques for debugging scientific applications on petascale architectures. In particular, we developed lightweight tools that narrow the problem space when bugs are encountered. We also developed techniques that either limit the number of tasks and the code regions to which a developer must apply a traditional debugger or that apply statistical techniques to provide direct suggestions of the location and type of error. We extend previous work on the Stack Trace Analysis Tool (STAT), that has already demonstrated scalability to over one hundred thousand MPI tasks. We also extended statistical techniques developed to isolate programming errors in widely used sequential or threaded applications in the Cooperative Bug Isolation (CBI) project to large scale parallel applications. Overall, our research substantially improved productivity on petascale platforms through a tool set for debugging that complements existing commercial tools. Previously, Office Of Science application developers relied either on primitive manual debugging techniques based on printf or they use tools, such as TotalView, that do not scale beyond a few thousand processors. However, bugs often arise at scale and substantial effort and computation cycles are wasted in either reproducing the problem in a smaller run that can be analyzed with the traditional tools or in repeated runs at scale that use the primitive techniques. New techniques that work at scale and automate the process of identifying the root cause of errors were needed. These techniques significantly reduced the time spent debugging petascale applications, thus leading to a greater overall amount of time for application scientists to pursue the scientific objectives for which the systems are purchased. We developed a new paradigm for debugging at scale: techniques that reduced the debugging scenario to a scale suitable for traditional debuggers, e.g., by narrowing the search for the root-cause analysis

  10. Class of near-perfect coded apertures

    International Nuclear Information System (INIS)

    Cannon, T.M.; Fenimore, E.E.

    1978-01-01

    The encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. If the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. The authors propose to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. The correlation of the decoding array with the aperture results in a delta function with deterministically zero sidelobes. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. 12 refs

  11. Solar energy apparatus with apertured shield

    Science.gov (United States)

    Collings, Roger J. (Inventor); Bannon, David G. (Inventor)

    1989-01-01

    A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

  12. Limited aperture effects on ultrasonic image reconstruction

    International Nuclear Information System (INIS)

    Kogan, V.G.; Rose, J.H.

    1985-01-01

    In the inverse Born approximation the shape of a weak scatterer can be determined from a knowledge of the backscattered ultrasonic amplitude for all directions of incidence and all frequencies. Two questions are considered. First, what information on the scatterer shape is preserved and what is degraded if the scattering data are available only within a limited set of incident directions (limited aperture). This problem is addressed for a spherical weakly scattering uniform flaw. It is shown that the problem of a general uniform ellipsoidal flaw can be reduced to the spherical case by a scale transformation; however, the apertures in these two cases must be related by the same transformation. Second, limited aperture and finite bandwidth Born inversions were performed for strongly scattering flaws (voids and cracks) using numerically generated scattering amplitudes. These inversions were then compared with the weak scattering analytic results, which show many common features

  13. Synthetic aperture tissue and flow ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav

    imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture......, on the other hand, can create a Bmode image with as little as 2 emissions, thus significantly speeding-up the scan procedure. The first part of the dissertation describes the synthetic aperture tissue imaging. It starts with an overview of the efforts previously made by other research groups. A classification...

  14. SPONGENT: The Design Space of Lightweight Cryptographic Hashing

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Knezevic, Miroslav; Leander, Gregor

    2013-01-01

    construction instantiated with present-type permutations. The resulting family of hash functions is called spongent. We propose 13 spongent variants--or different levels of collision and (second) preimage resistance as well as for various implementation constraints. For each of them, we provide several ASIC...

  15. Lightweight, High-Temperature Radiator for Space Propulsion

    Science.gov (United States)

    Hyers, R. W.; Tomboulian, B. N.; Crave, Paul D.; Rogers, J. R.

    2012-01-01

    For high-power nuclear-electric spacecraft, the radiator can account for 40% or more of the power system mass and a large fraction of the total vehicle mass. Improvements in the heat rejection per unit mass rely on lower-density and higher-thermal conductivity materials. Current radiators achieve near-ideal surface radiation through high-emissivity coatings, so improvements in heat rejection per unit area can be accomplished only by raising the temperature at which heat is rejected. We have been investigating materials that have the potential to deliver significant reductions in mass density and significant improvements in thermal conductivity, while expanding the feasible range of temperature for heat rejection up to 1000 K and higher. The presentation will discuss the experimental results and models of the heat transfer in matrix-free carbon fiber fins. Thermal testing of other carbon-based fin materials including carbon nanotube cloth and a carbon nanotube composite will also be presented.

  16. A method to select aperture margin in collimated spot scanning proton therapy

    International Nuclear Information System (INIS)

    Wang, Dongxu; Smith, Blake R; Gelover, Edgar; Flynn, Ryan T; Hyer, Daniel E

    2015-01-01

    The use of collimator or aperture may sharpen the lateral dose gradient for spot scanning proton therapy. However, to date, there has not been a standard method to determine the aperture margin for a single field in collimated spot scanning proton therapy. This study describes a theoretical framework to select the optimal aperture margin for a single field, and also presents the spot spacing limit required such that the optimal aperture margin exists. Since, for a proton pencil beam partially intercepted by collimator, the maximum point dose (spot center) shifts away from the original pencil beam central axis, we propose that the optimal margin should be equal to the maximum pencil beam center shift under the condition that spot spacing is small with respect to the maximum pencil beam center shift, which can be numerically determined based on beam modeling data. A test case is presented which demonstrates agreement with the prediction made based on the proposed methods. When apertures are applied in a commercial treatment planning system this method may be implemented. (note)

  17. Fast decoding algorithms for coded aperture systems

    International Nuclear Information System (INIS)

    Byard, Kevin

    2014-01-01

    Fast decoding algorithms are described for a number of established coded aperture systems. The fast decoding algorithms for all these systems offer significant reductions in the number of calculations required when reconstructing images formed by a coded aperture system and hence require less computation time to produce the images. The algorithms may therefore be of use in applications that require fast image reconstruction, such as near real-time nuclear medicine and location of hazardous radioactive spillage. Experimental tests confirm the efficacy of the fast decoding techniques

  18. Aperture and optics–measurements and conclusions

    CERN Document Server

    Redaelli, S; Bruce, R; Buffat, X; Giovannozzi, M; Lamont, M; Miyamoto, R; Müller, G; Tomás, R; Vanbavinckhove, G; Wenninger, J

    2012-01-01

    In 2011, the LHC has delivered collisions with different optics configurations in the four interaction points, at an operating energy of 3.5 TeV. The performance has been pushed during the year until a final configuration with 3 IPs squeezed to 1 m was achieved. Correspondingly, the machine aperture has been measured in the different configurations at injection and at top energy, to ensure a safe operation in all conditions of $\\beta^*$ and crossing angle configuration. In this paper, the 2011 commissioning experience of LHC optics is reviewed and the results of aperture measurements are presented. Measurement requirements for 2012 and possible improvements are also discussed.

  19. Synthetic aperture radar capabilities in development

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  20. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin

    2013-01-01

    Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

  1. Electromagnetic field scattering by a triangular aperture.

    Science.gov (United States)

    Harrison, R E; Hyman, E

    1979-03-15

    The multiple Laplace transform has been applied to analysis and computation of scattering by a double triangular aperture. Results are obtained which match far-field intensity distributions observed in experiments. Arbitrary polarization components, as well as in-phase and quadrature-phase components, may be determined, in the transform domain, as a continuous function of distance from near to far-field for any orientation, aperture, and transformable waveform. Numerical results are obtained by application of numerical multiple inversions of the fully transformed solution.

  2. Type Classes for Lightweight Substructural Types

    Directory of Open Access Journals (Sweden)

    Edward Gan

    2015-02-01

    Full Text Available Linear and substructural types are powerful tools, but adding them to standard functional programming languages often means introducing extra annotations and typing machinery. We propose a lightweight substructural type system design that recasts the structural rules of weakening and contraction as type classes; we demonstrate this design in a prototype language, Clamp. Clamp supports polymorphic substructural types as well as an expressive system of mutable references. At the same time, it adds little additional overhead to a standard Damas-Hindley-Milner type system enriched with type classes. We have established type safety for the core model and implemented a type checker with type inference in Haskell.

  3. Modal analysis for floors in lightweight buildings

    DEFF Research Database (Denmark)

    Sjökvist, Lars-Göran; Brunskog, Jonas

    2007-01-01

    of acoustical prediction methods for those houses. The calculation standard EN 12354 is under evaluation since it cannot include most of the wooden houses that are built. It is important during such a work to have a great understanding of the acoustical behaviour for the wooden houses. The floors in lightweight...... constructions usually consist of plates that are stiffened by beams and by the dividing walls. In this study the wave equation for a plate is expanded by Fourier series and an analytical solution in terms of the eigenmodes of the entire system is presented. The studied system consists of one lightweigt floor...

  4. Lightweight ozonizer for field and airborne use

    Science.gov (United States)

    Stone, E. J.; Caldwell, J. R.; de Waal, C.; Horvath, J. J.; Pearson, R., Jr.; Stedman, D. H.

    1982-12-01

    An efficient, lightweight apparatus for the production of ozone in flowing oxygen or air has been constructed and tested. The exciter is an automotive electronic ignition running from a 28-V dc power source. The discharge tube consists of coaxial conductive-coated flint glass tubing fitting into Teflon end pieces. A single such unit will produce 4% ozone in oxygen flowing at 0.2 l/min, or a maximum of 0.020 l of ozone per minute in a total flow of 1.0 l/min.

  5. Longbow: A Lightweight Remote Job Submission Tool

    Directory of Open Access Journals (Sweden)

    James Gebbie-Rayet

    2016-01-01

    Full Text Available We present Longbow, a lightweight console-based remote job submission tool and library. Longbow allows the user to quickly and simply run jobs on high performance computing facilities without leaving their familiar desktop environment. Not only does Longbow greatly simplify the management of compute- intensive jobs for experienced researchers, it also lowers the technical barriers surrounding high perfor-mance computation for the next generation of scientists and engineers. Longbow has already been used to remotely submit jobs in a number of projects and has the potential to redefine the manner in which high performance computers are used.

  6. A Light-Weight Instrumentation System Design

    International Nuclear Information System (INIS)

    Kidner, Ronald

    1999-01-01

    To meet challenging constraints on telemetry system weight and volume, a custom Light-Weight Instrumentation System was developed to collect vehicle environment and dynamics on a short-duration exo-atmospheric flight test vehicle. The total telemetry system, including electronics, sensors, batteries, and a 1 watt transmitter weighs about 1 kg. Over 80 channels of measurement, housekeeping, and telemetry system diagnostic data are transmitted at 128 kbps. The microcontroller-based design uses the automotive industry standard Controller Area Network to interface with and support in-flight control fimctions. Operational parameters are downloaded via a standard asynchronous serial communications intefiace. The basic design philosophy and functionality is described here

  7. Crushing and Fracture of Lightweight Structures

    DEFF Research Database (Denmark)

    Urban, Jesper

    2003-01-01

    and Latham (1968). Good agreement between the analytical models and the experiments is found. The crushing behaviour of two high speed ferries has been analysed with the numerical and analytical methods and the results are compared with the existing regulations for high speed craft (HSC). Several failure......The overall objective of the present study has been to develop rational analytical and numerical calculation models to quantify the consequences of collision accidents. The work has primarily been focused on high speed craft (HSC) built in lightweight materials such as aluminium and sandwich...

  8. Mix design and properties of fly ash waste lightweight aggregates in structural lightweight concrete

    Directory of Open Access Journals (Sweden)

    Manu S. Nadesan

    2017-12-01

    Full Text Available Concrete is one of the most widely used construction materials and has the ability to consume industrial wastes in high volume. As the demand for concrete is increasing, one of the effective ways to reduce the undesirable environmental impact of the concrete is by the use of waste and by-product materials as cement and aggregate substitutes in concrete. One such waste material is fly ash, which is produced in large quantities from thermal power plants as a by-product. A substantial amount of fly ash is left unused posing environmental and storage problems. The production of sintered lightweight aggregate with fly ash is an effective method to dispose of fly ash in large quantities. Due to lack of a proper mix design procedure, the production and application of lightweight aggregate in structural concrete are not much entertained. The absorption characteristic of lightweight aggregate is a major concern, while developing the mix proportioning of lightweight concretes. The present study is an attempt to establish a new mix design procedure for the development of sintered fly ash lightweight aggregate concretes, which is simple and more reliable than the existing procedures. Also, the proposed methodology has been validated by developing a spectrum of concretes having water cement ratios varying from 0.25 to 0.75. From the study, it is obvious that the development of 70 MPa concrete is possible by using cement alone without any additives. Also, it is ensured that all the concretes have densities less than 2000 kg/m3.

  9. Improved Large Aperture Collector Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    O' Rourke, Deven [Abengoa Solar LLC, Lakewood, CO (United States); Farr, Adrian [Abengoa Solar LLC, Lakewood, CO (United States)

    2015-12-01

    The parabolic trough is the most established CSP technology and carries a long history of design experimentation dating back to the 1970’s. This has led to relatively standardized collector architectures, a maturing global supply chain, and a fairly uniform cost reduction strategy. Abengoa has deployed more than 1,500MWe of CSP troughs across several countries and has built and tested full-scale prototypes of many R&D concepts. The latest trough R&D efforts involved efforts to internalize non-CSP industry experience including a preliminary DFMA principles review done with Boothroyd Dewhurst, a construction literature review by the Arizona State University School of Construction Management, and two more focused manufacturing engineering subcontracts done by Ricardo Inc. and the nonprofit Edison Welding Institute. The first two studies highlighted strong opportunities in lowering part count, standardizing components and fasteners, developing modular designs to support prefabrication and automation, and devising simple, error-proof manual assembly methods. These principles have delivered major new cost savings in otherwise “mature” products in analogous industries like automotive, truck trailer manufacture, metal building fabrication, and shipbuilding. For this reason, they were core in the design development of the SpaceTube® collector, and arguably key to its early successes. The latter two studies were applied specifically to the first-generation SpaceTube® design and were important in setting the direction of the present SolarMat project. These studies developed a methodology to analyze the costs of manufacture and assembly, and identify new tooling concepts for more efficient manufacture. Among the main opportunities identified in these studies were the automated mirror arm manufacturing concept and the need for a less infrastructure-intensive assembly line, both of which now form central pillars of the SolarMat project strategy. These new designs will be

  10. Calibration of circular aperture area using vision probe at inmetro

    Directory of Open Access Journals (Sweden)

    Costa Pedro Bastos

    2016-01-01

    Full Text Available Circular aperture areas are standards of high importance for the realization of photometric and radiometric measurements, where the accuracy of these measures is related to the accuracy of the circular aperture area calibrations. In order to attend the requirement for traceability was developed in Brazilian metrology institute, a methodology for circular aperture area measurement as requirements from the radiometric and photometric measurements. In the developed methodology apertures are measured by non-contact measurement through images of the aperture edges captured by a camera. These images are processed using computer vision techniques and then the values of the circular aperture area are determined.

  11. Dynamic Aperture Studies for SPEAR 3

    International Nuclear Information System (INIS)

    Nosochkov, Yuri

    1999-01-01

    The SSRL is investigating an accelerator upgrade project to replace the present 130 nm.rad FODO lattice with an 18 nm.rad double bend achromat lattice: SPEAR 3. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including optimization of linear optics, betatron tune, chromaticity and coupling correction, and effects of machine errors and insertion devices

  12. Diffraction contrast imaging using virtual apertures

    International Nuclear Information System (INIS)

    Gammer, Christoph; Burak Ozdol, V.; Liebscher, Christian H.; Minor, Andrew M.

    2015-01-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field

  13. Dynamic metamaterial aperture for microwave imaging

    International Nuclear Information System (INIS)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R.

    2015-01-01

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture

  14. Optimization of Synthetic Aperture Image Quality

    DEFF Research Database (Denmark)

    Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando

    2016-01-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameter...

  15. Dynamic metamaterial aperture for microwave imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)

    2015-11-16

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  16. Parametric Transverse Patterns in Broad Aperture Lasers

    DEFF Research Database (Denmark)

    Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik

    1998-01-01

    Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...... on the geometrical size of the system is demonstrated even in the case of large-scale systems....

  17. Sonar path correction in synthetic aperture processing

    NARCIS (Netherlands)

    Groen, J.; Hansen, R.E.; Sabel, J.C.

    2003-01-01

    In the next generation of mine hunting sonars, in particular on Autonomous Underwater Vehicles (AUVs), Synthetic Aperture Sonar (SAS) will play an important role. The benefit of SAS is to increase resolution and signal-tonoise ratio by coherent processing of successive pings. A challenge in SAS is

  18. Synthetic Aperture Beamformation using the GPU

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Schaa, Dana; Jensen, Jørgen Arendt

    2011-01-01

    A synthetic aperture ultrasound beamformer is implemented for a GPU using the OpenCL framework. The implementation supports beamformation of either RF signals or complex baseband signals. Transmit and receive apodization can be either parametric or dynamic using a fixed F-number, a reference...

  19. Wind energy applications of synthetic aperture radar

    DEFF Research Database (Denmark)

    Badger, Merete

    Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting windfields are valuable in offshore wind energy plan...

  20. MD2725: 16L2 aperture measurement

    CERN Document Server

    Mirarchi, Daniele; Rossi, Roberto; CERN. Geneva. ATS Department

    2018-01-01

    Dumps induced by sudden increase of losses in the half-cell 16L2 have been a serious machine limitation during the 2017 run. The aim of this MD was to perform local aperture measurements in order to assess differences after the beam screen regeneration, compared to first measurements in 2017.

  1. A Lightweight Protocol for Secure Video Streaming.

    Science.gov (United States)

    Venčkauskas, Algimantas; Morkevicius, Nerijus; Bagdonas, Kazimieras; Damaševičius, Robertas; Maskeliūnas, Rytis

    2018-05-14

    The Internet of Things (IoT) introduces many new challenges which cannot be solved using traditional cloud and host computing models. A new architecture known as fog computing is emerging to address these technological and security gaps. Traditional security paradigms focused on providing perimeter-based protections and client/server point to point protocols (e.g., Transport Layer Security (TLS)) are no longer the best choices for addressing new security challenges in fog computing end devices, where energy and computational resources are limited. In this paper, we present a lightweight secure streaming protocol for the fog computing "Fog Node-End Device" layer. This protocol is lightweight, connectionless, supports broadcast and multicast operations, and is able to provide data source authentication, data integrity, and confidentiality. The protocol is based on simple and energy efficient cryptographic methods, such as Hash Message Authentication Codes (HMAC) and symmetrical ciphers, and uses modified User Datagram Protocol (UDP) packets to embed authentication data into streaming data. Data redundancy could be added to improve reliability in lossy networks. The experimental results summarized in this paper confirm that the proposed method efficiently uses energy and computational resources and at the same time provides security properties on par with the Datagram TLS (DTLS) standard.

  2. Direct aperture optimization for IMRT using Monte Carlo generated beamlets

    International Nuclear Information System (INIS)

    Bergman, Alanah M.; Bush, Karl; Milette, Marie-Pierre; Popescu, I. Antoniu; Otto, Karl; Duzenli, Cheryl

    2006-01-01

    This work introduces an EGSnrc-based Monte Carlo (MC) beamlet does distribution matrix into a direct aperture optimization (DAO) algorithm for IMRT inverse planning. The technique is referred to as Monte Carlo-direct aperture optimization (MC-DAO). The goal is to assess if the combination of accurate Monte Carlo tissue inhomogeneity modeling and DAO inverse planning will improve the dose accuracy and treatment efficiency for treatment planning. Several authors have shown that the presence of small fields and/or inhomogeneous materials in IMRT treatment fields can cause dose calculation errors for algorithms that are unable to accurately model electronic disequilibrium. This issue may also affect the IMRT optimization process because the dose calculation algorithm may not properly model difficult geometries such as targets close to low-density regions (lung, air etc.). A clinical linear accelerator head is simulated using BEAMnrc (NRC, Canada). A novel in-house algorithm subdivides the resulting phase space into 2.5x5.0 mm 2 beamlets. Each beamlet is projected onto a patient-specific phantom. The beamlet dose contribution to each voxel in a structure-of-interest is calculated using DOSXYZnrc. The multileaf collimator (MLC) leaf positions are linked to the location of the beamlet does distributions. The MLC shapes are optimized using direct aperture optimization (DAO). A final Monte Carlo calculation with MLC modeling is used to compute the final dose distribution. Monte Carlo simulation can generate accurate beamlet dose distributions for traditionally difficult-to-calculate geometries, particularly for small fields crossing regions of tissue inhomogeneity. The introduction of DAO results in an additional improvement by increasing the treatment delivery efficiency. For the examples presented in this paper the reduction in the total number of monitor units to deliver is ∼33% compared to fluence-based optimization methods

  3. Proposal of a relationship between dynamic aperture adn intensity evolution in a storage ring

    CERN Document Server

    Giovannozzi, M

    2010-01-01

    A scaling law for the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers, about ten years ago. The use of fundamental theorems of the theory of dynamical systems allowed showing that the dynamic aperture has a logarithmic dependence on time. In this paper this result, proved by mean of numerical simulations, is used as a basis for deriving a scaling law for the intensity evolution in a storage ring. The proposed scaling law is also tested against experimental data showing a remarkable agreement.

  4. Comparisons of coded aperture imaging using various apertures and decoding methods

    International Nuclear Information System (INIS)

    Chang, L.T.; Macdonald, B.; Perez-Mendez, V.

    1976-07-01

    The utility of coded aperture γ camera imaging of radioisotope distributions in Nuclear Medicine is in its ability to give depth information about a three dimensional source. We have calculated imaging with Fresnel zone plate and multiple pinhole apertures to produce coded shadows and reconstruction of these shadows using correlation, Fresnel diffraction, and Fourier transform deconvolution. Comparisons of the coded apertures and decoding methods are made by evaluating their point response functions both for in-focus and out-of-focus image planes. Background averages and standard deviations were calculated. In some cases, background subtraction was made using combinations of two complementary apertures. Results using deconvolution reconstruction for finite numbers of events are also given

  5. Testosterone and BMD in elite male lightweight rowers

    DEFF Research Database (Denmark)

    Vinther, A; Kanstrup, I-L; Christiansen, E

    2008-01-01

    The purpose of the present study was to investigate if a relationship between BMD and testosterone levels could be identified in elite male lightweight rowers. Thirteen male lightweight national team rowers had their BMD measured in a DEXA scanner. Plasma concentrations of total testosterone (TT)...

  6. Investigation on Wall Panel Sandwiched With Lightweight Concrete

    Science.gov (United States)

    Lakshmikandhan, K. N.; Harshavardhan, B. S.; Prabakar, J.; Saibabu, S.

    2017-08-01

    The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of sandwich wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.

  7. Uncertainty and Variation of Vibration in Lightweight Structures

    DEFF Research Database (Denmark)

    Dickow, Kristoffer Ahrens

    2012-01-01

    Multi-family dwellings and offices build from lightweight materials are becoming a cost efficient and environmentally friendly alternative to traditional heavy structures.......Multi-family dwellings and offices build from lightweight materials are becoming a cost efficient and environmentally friendly alternative to traditional heavy structures....

  8. Olive pomace based lightweight concrete, an experimental approach and contribution

    Directory of Open Access Journals (Sweden)

    Lynda Amel Chaabane

    2018-01-01

    Full Text Available Due to conventional aggregates resources depletion, material recycling has become an economic and ecologic alternative. In this paper, locally available natural residues such as olive pomace were investigated, when partially incorporated in the concrete formulation, since the mechanical characteristics of lightweight aggregate concrete strongly depend on its properties and proportions. Lightweight aggregates are more deformable than the cement matrix because of their high porosity, and their influence on the concrete strength remains complex. The purpose of this paper is to investigate the aggregates properties on lightweight concrete mechanical behaviour through an experimental approach. In addition, the different substitution sequences and the W/C ratio on lightweight concrete behaviour were evaluated, in order to determine the W/C ratio influence on the improvement of the lightweight concrete mechanical properties while knowing that the mixing water quantity gives the cement paste manoeuvrability and mechanical strength effects. The last part of this paper, therefore, was to provide statistical survey for estimating strength and weight reduction through the different natural aggregate substitutions to improve the lightweight concrete properties. The results achieved in a significant olive-pomace lower adhesion with the matrix after the cement setting, making the lightweight concrete mechanical strength weak. However, this work can open several perspectives: Results modeling and correlation with an experimental approach, the evolution and determination of lightweight concrete characteristics when exposed to high temperatures and thermohydric properties.

  9. FY2014 Lightweight Materials R&D Annual Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    None

    2015-03-01

    The Lightweight Materials research and development (R&D) area within the DOE Vehicle Technologies Office (VTO) provides support and guidance for many cutting-edge automotive technologies under development. Research focuses on addressing critical barriers to commercializing lightweight materials for passenger and commercial vehicles.

  10. Mitigation of Flanking Noise Transmission in Periodic Structures of Lightweight Elements

    DEFF Research Database (Denmark)

    Domadiya, Parthkumar Gandalal

    through structural junctions and radiates into neighbouring rooms. To diminish the flanking transmission of sound, frames are usually designed with single or double studs or constructed with layers of foam or another viscoelastic material. This thesis is investigating the behaviour of flanking noise...... transmission in periodic structures of lightweight elements by employing various numerical, analytical and experimental methods. At first, three dimensional finite-element (FE) models of a Z-shaped lightweight panel structure based on various frame designs, inclusion of air and structural coupling between...... elements are considered for describing flanking noise transmission through panels. It is assumed that the ribs are fully fixed to the plates in case of various frame designs, and a parametric study is carried out on the centre panel with regard to various spacing between the ribs. Solid finite elements...

  11. Ships as salient objects in synthetic aperture radar imaginary

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2016-07-01

    Full Text Available The widespread access to Synthetic Aperture Radar data has created a need for more precise ship extraction, specifically in low-to-medium resolution imagery. While Synthetic Aperture Radar pixel resolution is improving for a large swaths...

  12. Sea Ice Monitoring from Space with Synthetic Aperture Radar

    Science.gov (United States)

    Eltoft, T.; Dierking, W.; Doulgeris, A.; Kasapoglu, G.; Kraemer, T.

    2013-03-01

    This paper summarizes the knowledge status in some areas of SAR monitoring of sea ice. It starts with a brief summary of the whitepaper by Breivik et al. from OceanObs’09 [3], and then focuses on segmentation and classification, drift estimation, and assimilation strategies, which are considered as key areas in the development of more mature sea ice products from SAR and polarimetric SAR (PoLSAR) data.

  13. Advanced Gas Sensing Technology for Space Suits, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced space suits require lightweight, low-power, durable sensors for monitoring critical life support materials. No current compact sensors have the tolerance...

  14. Telescope aperture optimization for spacebased coherent wind lidar

    Science.gov (United States)

    Ge, Xian-ying; Zhu, Jun; Cao, Qipeng; Zhang, Yinchao; Yin, Huan; Dong, Xiaojing; Wang, Chao; Zhang, Yongchao; Zhang, Ning

    2015-08-01

    Many studies have indicated that the optimum measurement approach for winds from space is a pulsed coherent wind lidar, which is an active remote sensing tool with the characteristics that high spatial and temporal resolutions, real-time detection, high mobility, facilitated control and so on. Because of the significant eye safety, efficiency, size, and lifetime advantage, 2μm wavelength solid-state laser lidar systems have attracted much attention in spacebased wind lidar plans. In this paper, the theory of coherent detection is presented and a 2μm wavelength solid-state laser lidar system is introduced, then the ideal aperture is calculated from signal-to-noise(SNR) view at orbit 400km. However, considering real application, even if the lidar hardware is perfectly aligned, the directional jitter of laser beam, the attitude change of the lidar in the long round trip time of the light from the atmosphere and other factors can bring misalignment angle. So the influence of misalignment angle is considered and calculated, and the optimum telescope diameter(0.45m) is obtained as the misalignment angle is 4 μrad. By the analysis of the optimum aperture required for spacebased coherent wind lidar system, we try to present the design guidance for the telescope.

  15. Study of Wide Swath Synthetic Aperture Ladar Imaging Techology

    Directory of Open Access Journals (Sweden)

    Zhang Keshu

    2017-02-01

    Full Text Available Combining synthetic-aperture imaging and coherent-light detection technology, the weak signal identification capacity of Synthetic Aperture Ladar (SAL reaches the photo level, and the image resolution exceeds the diffraction limit of the telescope to obtain high-resolution images irrespective to ranges. This paper introduces SAL, including the development path, technology characteristics, and the restriction of imaging swath. On the basis of this, we propose to integrate the SAL technology for extending its swath. By analyzing the scanning-operation mode and the signal model, the paper explicitly proposes that the former mode will be the developmental trend of the SAL technology. This paper also introduces the flight demonstrations of the SAL and the imaging results of remote targets, showing the potential of the SAL in long-range, high-resolution, and scanning-imaging applications. The technology and the theory of the scanning mode of SAL compensates for the defects related to the swath and operation efficiency of the current SAL. It provides scientific foundation for the SAL system applied in wide swath, high resolution earth observation, and the ISAL system applied in space-targets imaging.

  16. Stitching Type Large Aperture Depolarizer for Gas Monitoring Imaging Spectrometer

    Science.gov (United States)

    Liu, X.; Li, M.; An, N.; Zhang, T.; Cao, G.; Cheng, S.

    2018-04-01

    To increase the accuracy of radiation measurement for gas monitoring imaging spectrometer, it is necessary to achieve high levels of depolarization of the incoming beam. The preferred method in space instrument is to introduce the depolarizer into the optical system. It is a combination device of birefringence crystal wedges. Limited to the actual diameter of the crystal, the traditional depolarizer cannot be used in the large aperture imaging spectrometer (greater than 100 mm). In this paper, a stitching type depolarizer is presented. The design theory and numerical calculation model for dual babinet depolarizer were built. As required radiometric accuracies of the imaging spectrometer with 250 mm × 46 mm aperture, a stitching type dual babinet depolarizer was design in detail. Based on designing the optimum structural parmeters the tolerance of wedge angle refractive index, and central thickness were given. The analysis results show that the maximum residual polarization degree of output light from depolarizer is less than 2 %. The design requirements of polarization sensitivity is satisfied.

  17. STITCHING TYPE LARGE APERTURE DEPOLARIZER FOR GAS MONITORING IMAGING SPECTROMETER

    Directory of Open Access Journals (Sweden)

    X. Liu

    2018-04-01

    Full Text Available To increase the accuracy of radiation measurement for gas monitoring imaging spectrometer, it is necessary to achieve high levels of depolarization of the incoming beam. The preferred method in space instrument is to introduce the depolarizer into the optical system. It is a combination device of birefringence crystal wedges. Limited to the actual diameter of the crystal, the traditional depolarizer cannot be used in the large aperture imaging spectrometer (greater than 100 mm. In this paper, a stitching type depolarizer is presented. The design theory and numerical calculation model for dual babinet depolarizer were built. As required radiometric accuracies of the imaging spectrometer with 250 mm × 46 mm aperture, a stitching type dual babinet depolarizer was design in detail. Based on designing the optimum structural parmeters,the tolerance of wedge angle,refractive index, and central thickness were given. The analysis results show that the maximum residual polarization degree of output light from depolarizer is less than 2 %. The design requirements of polarization sensitivity is satisfied.

  18. The COronal Solar Magnetism Observatory (COSMO) Large Aperture Coronagraph

    Science.gov (United States)

    Tomczyk, Steve; Gallagher, Dennis; Wu, Zhen; Zhang, Haiying; Nelson, Pete; Burkepile, Joan; Kolinksi, Don; Sutherland, Lee

    2013-04-01

    The COSMO is a facility dedicated to observing coronal and chromospheric magnetic fields. It will be located on a mountaintop in the Hawaiian Islands and will replace the current Mauna Loa Solar Observatory (MLSO). COSMO will provide unique observations of the global coronal magnetic fields and its environment to enhance the value of data collected by other observatories on the ground (e.g. SOLIS, BBO NST, Gregor, ATST, EST, Chinese Giant Solar Telescope, NLST, FASR) and in space (e.g. SDO, Hinode, SOHO, GOES, STEREO, Solar-C, Solar Probe+, Solar Orbiter). COSMO will employ a fleet of instruments to cover many aspects of measuring magnetic fields in the solar atmosphere. The dynamics and energy flow in the corona are dominated by magnetic fields. To understand the formation of CMEs, their relation to other forms of solar activity, and their progression out into the solar wind requires measurements of coronal magnetic fields. The large aperture coronagraph, the Chromospheric and Prominence Magnetometer and the K-Coronagraph form the COSMO instrument suite to measure magnetic fields and the polarization brightness of the low corona used to infer electron density. The large aperture coronagraph will employ a 1.5 meter fuse silica singlet lens, birefringent filters, and a spectropolarimeter to cover fields of view of up to 1 degree. It will observe the corona over a wide range of emission lines from 530.3 nm through 1083.0 nm allowing for magnetic field measurements over a wide range of coronal temperatures (e.g. FeXIV at 530.3 nm, Fe X at 637.4 nm, Fe XIII at 1074.7 and 1079.8 nm. These lines are faint and require the very large aperture. NCAR and NSF have provided funding to bring the large aperture coronagraph to a preliminary design review state by the end of 2013. As with all data from Mauna Loa, the data products from COSMO will be available to the community via the Mauna Loa website: http://mlso.hao.ucar.edu

  19. Focusing optical waves with a rotationally symmetric sharp-edge aperture

    Science.gov (United States)

    Hu, Yanwen; Fu, Shenhe; Li, Zhen; Yin, Hao; Zhou, Jianying; Chen, Zhenqiang

    2018-04-01

    While there has been various kinds of patterned structures proposed for wave focusing, these patterned structures usually involve complicated lithographic techniques since the element size of the patterned structures should be precisely controlled in microscale or even nanoscale. Here we propose a new and straightforward method for focusing an optical plane wave in free space with a rotationally symmetric sharp-edge aperture. The focusing phenomenon of wave is realized by superposition of a portion of the higher-order symmetric plane waves generated from the sharp edges of the apertures, in contrast to previously focusing techniques which usually depend on a curved phase. We demonstrate both experimentally and theoretically the focusing effect with a series of apertures having different rotational symmetry, and find that the intensity of the hotspots could be controlled by the symmetric strength of the sharp-edge apertures. The presented results would advance the conventional wisdom that light would diffract in all directions and become expanding when it propagates through an aperture. The proposed method is easy to be processed, and might open potential applications in interferometry, image, and superresolution.

  20. Dual aperture dipole magnet with second harmonic component

    Science.gov (United States)

    Praeg, Walter F.

    1985-01-01

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  1. Fractal characteristics of fracture roughness and aperture data

    International Nuclear Information System (INIS)

    Kumar, S.; Boernge, J.

    1991-05-01

    In this study mathematical expressions are developed for the characteristics of apertures between rough surfaces. It has shown that the correlation between the opposite surfaces influences the aperture properties and different models are presented for these different surface correlations. Fracture and apertures profiles measured from intact fractures are evaluated and it is found that they qualitatively follow the mathematically predicted trends

  2. A lightweight communication library for distributed computing

    International Nuclear Information System (INIS)

    Groen, Derek; Rieder, Steven; Zwart, Simon Portegies; Grosso, Paola; Laat, Cees de

    2010-01-01

    We present MPWide, a platform-independent communication library for performing message passing between computers. Our library allows coupling of several local message passing interface (MPI) applications through a long-distance network and is specifically optimized for such communications. The implementation is deliberately kept lightweight and platform independent, and the library can be installed and used without administrative privileges. The only requirements are a C++ compiler and at least one open port to a wide-area network on each site. In this paper we present the library, describe the user interface, present performance tests and apply MPWide in a large-scale cosmological N-body simulation on a network of two computers, one in Amsterdam and the other in Tokyo.

  3. Lightweight, durable lead-acid batteries

    Science.gov (United States)

    Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O; Dudney, Nancy J; Contescu, Cristian I; Baker, Frederick S; Armstrong, Beth L

    2013-05-21

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  4. Lightweight Active Object Retrieval with Weak Classifiers.

    Science.gov (United States)

    Czúni, László; Rashad, Metwally

    2018-03-07

    In the last few years, there has been a steadily growing interest in autonomous vehicles and robotic systems. While many of these agents are expected to have limited resources, these systems should be able to dynamically interact with other objects in their environment. We present an approach where lightweight sensory and processing techniques, requiring very limited memory and processing power, can be successfully applied to the task of object retrieval using sensors of different modalities. We use the Hough framework to fuse optical and orientation information of the different views of the objects. In the presented spatio-temporal perception technique, we apply active vision, where, based on the analysis of initial measurements, the direction of the next view is determined to increase the hit-rate of retrieval. The performance of the proposed methods is shown on three datasets loaded with heavy noise.

  5. Lightweight Active Object Retrieval with Weak Classifiers

    Directory of Open Access Journals (Sweden)

    László Czúni

    2018-03-01

    Full Text Available In the last few years, there has been a steadily growing interest in autonomous vehicles and robotic systems. While many of these agents are expected to have limited resources, these systems should be able to dynamically interact with other objects in their environment. We present an approach where lightweight sensory and processing techniques, requiring very limited memory and processing power, can be successfully applied to the task of object retrieval using sensors of different modalities. We use the Hough framework to fuse optical and orientation information of the different views of the objects. In the presented spatio-temporal perception technique, we apply active vision, where, based on the analysis of initial measurements, the direction of the next view is determined to increase the hit-rate of retrieval. The performance of the proposed methods is shown on three datasets loaded with heavy noise.

  6. Protect sensitive data with lightweight memory encryption

    Science.gov (United States)

    Zhou, Hongwei; Yuan, Jinhui; Xiao, Rui; Zhang, Kai; Sun, Jingyao

    2018-04-01

    Since current commercial processor is not able to deal with the data in the cipher text, the sensitive data have to be exposed in the memory. It leaves a window for the adversary. To protect the sensitive data, a direct idea is to encrypt the data when the processor does not access them. On the observation, we have developed a lightweight memory encryption, called LeMe, to protect the sensitive data in the application. LeMe marks the sensitive data in the memory with the page table entry, and encrypts the data in their free time. LeMe is built on the Linux with a 3.17.6 kernel, and provides four user interfaces as dynamic link library. Our evaluations show LeMe is effective to protect the sensitive data and incurs an acceptable performance overhead.

  7. Development of a lightweight fuel cell vehicle

    Science.gov (United States)

    Hwang, J. J.; Wang, D. Y.; Shih, N. C.

    This paper described the development of a fuel cell system and its integration into the lightweight vehicle known as the Mingdao hydrogen vehicle (MHV). The fuel cell system consists of a 5-kW proton exchange membrane fuel cell (PEMFC), a microcontroller and other supported components like a compressed hydrogen cylinder, blower, solenoid valve, pressure regulator, water pump, heat exchanger and sensors. The fuel cell not only propels the vehicle but also powers the supporting components. The MHV performs satisfactorily over a hundred-kilometer drive thus validating the concept of a fuel cell powered zero-emission vehicle. Measurements further show that the fuel cell system has an efficiency of over 30% at the power consumption for vehicle cruise, which is higher than that of a typical internal combustion engine. Tests to improve performance such as speed enhancement, acceleration and fuel efficiency will be conducted in the future work. Such tests will consist of hybridizing with a battery pack.

  8. Lightweight MIPv6 with IPSec Support

    Directory of Open Access Journals (Sweden)

    Antonio J. Jara

    2014-01-01

    Full Text Available Mobility management is a desired feature for the emerging Internet of Things (IoT. Mobility aware solutions increase the connectivity and enhance adaptability to changes of the location and infrastructure. IoT is enabling a new generation of dynamic ecosystems in environments such as smart cities and hospitals. Dynamic ecosystems require ubiquitous access to Internet, seamless handover, flexible roaming policies, and an interoperable mobility protocol with existing Internet infrastructure. These features are challenges for IoT devices, which are usually constrained devices with low memory, processing, communication and energy capabilities. This work presents an analysis of the requirements and desirable features for the mobility support in the IoT, and proposes an efficient solution for constrained environments based on Mobile IPv6 and IPSec. Compatibility with IPv6-existing protocols has been considered a major requirement in order to offer scalable and inter-domain solutions that were not limited to specific application domains in order to enable a new generation of application and services over Internet-enabled dynamic ecosystems, and security support based on IPSec has been also considered, since dynamic ecosystems present several challenges in terms of security and privacy. This work has, on the one hand, analysed suitability of Mobile IPv6 and IPSec for constrained devices, and on the other hand, analysed, designed, developed and evaluated a lightweight version of Mobile IPv6 and IPSec. The proposed solution of lightweight Mobile IPv6 with IPSec is aware of the requirements of the IoT and presents the best solution for dynamic ecosystems in terms of efficiency and security adapted to IoT-devices capabilities. This presents concerns in terms of higher overhead and memory requirements. But, it is proofed and concluded that even when higher memory is required and major overhead is presented, the integration of Mobile IPv6 and IPSec for

  9. Dynamic Aperture Studies for SPEAR 3

    International Nuclear Information System (INIS)

    Corbett, William

    1998-01-01

    The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm rad FODO lattice with an 18 nm rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity

  10. Dynamic aperture studies for SPEAR 3

    International Nuclear Information System (INIS)

    Nosochkov, Y.; Corbett, J.

    1999-01-01

    The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm·rad FODO lattice with an 18 nm·rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity

  11. High frame rate synthetic aperture duplex imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes

    2013-01-01

    aperture flow imaging as demonstrated in this paper. Synthetic aperture, directional beamforming, and cross-correlation are used to produce B-mode and vector velocity images at high frame rates. The frame rate equals the effective pulse repetition frequency of each imaging mode. Emissions for making the B...... estimation is −1.8% and the relative standard deviation 5.4%. The approach can thus estimate both high and low velocities with equal accuracy and thereby makes it possible to present vector flow images with a high dynamic range. Measurements are made using the SARUS research scanner, a linear array......Conventional color flow images are limited in velocity range and can either show the high velocities in systole or be optimized for the lower diastolic velocities. The full dynamics of the flow is, thus, hard to visualize. The dynamic range can be significantly increased by employing synthetic...

  12. Lightweight males of Podisus nigrispinus (Heteroptera: Pentatomidae neglect lightweight females due low reproductive fitness

    Directory of Open Access Journals (Sweden)

    A. I. A. Pereira

    Full Text Available Abstract Sexual choice by male stink bugs is important because females that experience food shortages lay fewer eggs with lower viability compared with well-fed females. In this study, we investigated whether Podisus nigrispinus (Dallas (Heteroptera: Pentatomidae males fed with a low-quality diet during its nymphal stage show selectivity for sexual partners resulting in high-quality progeny. Lightweight males and females were obtained from nymphs fed weekly with Tenebrio molitor L. (Coleoptera: Tenebrionidae pupae. By contrast, heavyweight males and females were fed three times a week and received an extra nutritional source: cotton leaves, Gossypium hirsutum L. (Malvaceae. Lightweight males preferred to mate with heavy females (77.78 ± 14.69%, whereas heavyweight males did not discriminated between light or heavyweight females. Females mated with lightweight males showed similar levels of reproduction to those mated with heavyweight males. The results provide an indication of the importance of male and female body weight for sexual selection in Asopinae stink bugs.

  13. Class of near-perfect coded apertures

    International Nuclear Information System (INIS)

    Cannon, T.M.; Fenimore, E.E.

    1977-01-01

    Coded aperture imaging of gamma ray sources has long promised an improvement in the sensitivity of various detector systems. The promise has remained largely unfulfilled, however, for either one of two reasons. First, the encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. Second, if the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. It is proposed to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. In the case of a large detector background noise the URA will always do much better than the single pinhole regardless of the structure of the object. In the case of a low detector background noise, the improvement of the URA over the single pinhole will have a lower limit of approximately (1/2f)/sup 1 / 2 / where f is the fraction of the field of view which is uniformly filled by the object

  14. Large-aperture hybrid photo-detector

    International Nuclear Information System (INIS)

    Kawai, Y.; Nakayama, H.; Kusaka, A.; Kakuno, H.; Abe, T.; Iwasaki, M.; Aihara, H.; Tanaka, M.; Shiozawa, M.; Kyushima, H.; Suyama, M.

    2007-01-01

    We have developed the first complete large-aperture (13-inch diameter) hybrid photo-detector (HPD). The withstanding voltage problem has been overcome and we were able to attain an HPD operating voltage of +20 kV. Adoption of our newly developed backside illumination avalanche diode (AD) was also critical in successfully countering the additional problem of an increase in AD leakage after the activation process. We observed single photon signal timing jitter of under 450 ps in FWHM, electron transit time of ∼12 ns, and clear pulse height separation up to several photoelectron peaks, all greatly superior to the performance of any conventional large-aperture photomultiplier tubes (PMTs). In addition, our HPD has a much simpler structure than conventional large-aperture PMTs, which simplifies mass production and lowers manufacturing cost. We believe that these attributes position our HPD as the most suitable photo-detector for the next generation mega-ton class water-Cherenkov detector, which is expected to be more than 20x larger than the Super-Kamiokande (SK) detector

  15. Biomineral repair of abalone shell apertures.

    Science.gov (United States)

    Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

    2013-08-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Initial Technology Assessment for the Large-Aperture UV-Optical-Infrared (LUVOIR) Mission Concept Study

    Science.gov (United States)

    Bolcar, Matthew R.; Feinberg, Lee; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-01-01

    The NASA Astrophysics Division's 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet/optical/infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for biosignatures via direct-imaging and spectroscopic characterization of habitable exoplanets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV/Optical/Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  17. Vehicle Lightweighting: Mass Reduction Spectrum Analysis and Process Cost Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Mascarin, Anthony [IBIS Associates, Inc., Waltham, MA (United States); Hannibal, Ted [IBIS Associates, Inc., Waltham, MA (United States); Raghunathan, Anand [Energetics Inc., Columbia, MD (United States); Ivanic, Ziga [Energetics Inc., Columbia, MD (United States); Clark, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    The U.S. Department of Energy’s Vehicle Technologies Office, Materials area commissioned a study to model and assess manufacturing economics of alternative design and production strategies for a series of lightweight vehicle concepts. In the first two phases of this effort examined combinations of strategies aimed at achieving strategic targets of 40% and a 45% mass reduction relative to a standard North American midsize passenger sedan at an effective cost of $3.42 per pound (lb) saved. These results have been reported in the Idaho National Laboratory report INL/EXT-14-33863 entitled Vehicle Lightweighting: 40% and 45% Weight Savings Analysis: Technical Cost Modeling for Vehicle Lightweighting published in March 2015. The data for these strategies were drawn from many sources, including Lotus Engineering Limited and FEV, Inc. lightweighting studies, U.S. Department of Energy-funded Vehma International of America, Inc./Ford Motor Company Multi-Material Lightweight Prototype Vehicle Demonstration Project, the Aluminum Association Transportation Group, many United States Council for Automotive Research’s/United States Automotive Materials Partnership LLC lightweight materials programs, and IBIS Associates, Inc.’s decades of experience in automotive lightweighting and materials substitution analyses.

  18. Vehicle Lightweighting: Mass Reduction Spectrum Analysis and Process Cost Modeling

    International Nuclear Information System (INIS)

    Mascarin, Anthony; Hannibal, Ted; Raghunathan, Anand; Ivanic, Ziga; Clark, Michael

    2016-01-01

    The U.S. Department of Energy's Vehicle Technologies Office, Materials area commissioned a study to model and assess manufacturing economics of alternative design and production strategies for a series of lightweight vehicle concepts. In the first two phases of this effort examined combinations of strategies aimed at achieving strategic targets of 40% and a 45% mass reduction relative to a standard North American midsize passenger sedan at an effective cost of $3.42 per pound (lb) saved. These results have been reported in the Idaho National Laboratory report INL/EXT-14-33863 entitled Vehicle Lightweighting: 40% and 45% Weight Savings Analysis: Technical Cost Modeling for Vehicle Lightweighting published in March 2015. The data for these strategies were drawn from many sources, including Lotus Engineering Limited and FEV, Inc. lightweighting studies, U.S. Department of Energy-funded Vehma International of America, Inc./Ford Motor Company Multi-Material Lightweight Prototype Vehicle Demonstration Project, the Aluminum Association Transportation Group, many United States Council for Automotive Research's/United States Automotive Materials Partnership LLC lightweight materials programs, and IBIS Associates, Inc.'s decades of experience in automotive lightweighting and materials substitution analyses.

  19. Carbody structural lightweighting based on implicit parameterized model

    Science.gov (United States)

    Chen, Xin; Ma, Fangwu; Wang, Dengfeng; Xie, Chen

    2014-05-01

    Most of recent research on carbody lightweighting has focused on substitute material and new processing technologies rather than structures. However, new materials and processing techniques inevitably lead to higher costs. Also, material substitution and processing lightweighting have to be realized through body structural profiles and locations. In the huge conventional workload of lightweight optimization, model modifications involve heavy manual work, and it always leads to a large number of iteration calculations. As a new technique in carbody lightweighting, the implicit parameterization is used to optimize the carbody structure to improve the materials utilization rate in this paper. The implicit parameterized structural modeling enables the use of automatic modification and rapid multidisciplinary design optimization (MDO) in carbody structure, which is impossible in the traditional structure finite element method (FEM) without parameterization. The structural SFE parameterized model is built in accordance with the car structural FE model in concept development stage, and it is validated by some structural performance data. The validated SFE structural parameterized model can be used to generate rapidly and automatically FE model and evaluate different design variables group in the integrated MDO loop. The lightweighting result of body-in-white (BIW) after the optimization rounds reveals that the implicit parameterized model makes automatic MDO feasible and can significantly improve the computational efficiency of carbody structural lightweighting. This paper proposes the integrated method of implicit parameterized model and MDO, which has the obvious practical advantage and industrial significance in the carbody structural lightweighting design.

  20. Wounding apertures: violence, affect and photography during and after apartheid

    Directory of Open Access Journals (Sweden)

    Kylie Thomas

    2012-01-01

    Full Text Available Between March and September 2012 there have been sixteen instances of 'necklacing' in the townships just outside of Cape Town. This article argues for understanding these events in relation to the violence of apartheid. It approaches the question of the meanings of the persistence of necklacing through an analysis of photographs of people who had been subject to vigilante violence in the 1980s. The article focuses on the work of Gille de Vlieg, a photographer who, during apartheid, was a member of the Black Sash and of the Afrapix photography collective. I read de Vlieg's photographs as a series of 'wounding apertures' that open a space for affective engagements with the violence of both the past and of the present. The importance of such engagements, the article argues, lies in what political philosopher Hannah Arendt has theorised as the constitutive relation between feeling, thinking and judging.

  1. Aperture Synthesis Methods and Applications to Optical Astronomy

    CERN Document Server

    Saha, Swapan Kumar

    2011-01-01

    Over the years long baseline optical interferometry has slowly gained in importance and today it is a powerful tool. This timely book sets out to highlight the basic principles of long baseline optical interferometry. The book addresses the fundamentals of stellar interferometry with emphasis on aperture synthesis using an array of telescopes particularly at optical/IR wavelengths. It discusses the fundamentals of electromagnetic fields, wave optics, interference, diffraction, and imaging at length. There is a chapter dedicated to radio and intensity interferometry corroborating with basic mathematical steps. The basic principle of optical interferometry and its requirements, its limitations and the technical challenges it poses, are also covered in depth. Assisted by illustrations and footnotes, the book examines the basic tricks of the trade, current trends and methods, and it points to the potential of true interferometry both from the ground and space.

  2. Segmented Aperture Interferometric Nulling Testbed (SAINT) II: component systems update

    Science.gov (United States)

    Hicks, Brian A.; Bolcar, Matthew R.; Helmbrecht, Michael A.; Petrone, Peter; Burke, Elliot; Corsetti, James; Dillon, Thomas; Lea, Andrew; Pellicori, Samuel; Sheets, Teresa; Shiri, Ron; Agolli, Jack; DeVries, John; Eberhardt, Andrew; McCabe, Tyler

    2017-09-01

    This work presents updates to the coronagraph and telescope components of the Segmented Aperture Interferometric Nulling Testbed (SAINT). The project pairs an actively-controlled macro-scale segmented mirror with the Visible Nulling Coronagraph (VNC) towards demonstrating capabilities for the future space observatories needed to directly detect and characterize a significant sample of Earth-sized worlds around nearby stars in the quest for identifying those which may be habitable and possibly harbor life. Efforts to improve the VNC wavefront control optics and mechanisms towards repeating narrowband results are described. A narrative is provided for the design of new optical components aimed at enabling broadband performance. Initial work with the hardware and software interface for controlling the segmented telescope mirror is also presented.

  3. Optimization of coronagraph design for segmented aperture telescopes

    Science.gov (United States)

    Jewell, Jeffrey; Ruane, Garreth; Shaklan, Stuart; Mawet, Dimitri; Redding, Dave

    2017-09-01

    The goal of directly imaging Earth-like planets in the habitable zone of other stars has motivated the design of coronagraphs for use with large segmented aperture space telescopes. In order to achieve an optimal trade-off between planet light throughput and diffracted starlight suppression, we consider coronagraphs comprised of a stage of phase control implemented with deformable mirrors (or other optical elements), pupil plane apodization masks (gray scale or complex valued), and focal plane masks (either amplitude only or complex-valued, including phase only such as the vector vortex coronagraph). The optimization of these optical elements, with the goal of achieving 10 or more orders of magnitude in the suppression of on-axis (starlight) diffracted light, represents a challenging non-convex optimization problem with a nonlinear dependence on control degrees of freedom. We develop a new algorithmic approach to the design optimization problem, which we call the "Auxiliary Field Optimization" (AFO) algorithm. The central idea of the algorithm is to embed the original optimization problem, for either phase or amplitude (apodization) in various planes of the coronagraph, into a problem containing additional degrees of freedom, specifically fictitious "auxiliary" electric fields which serve as targets to inform the variation of our phase or amplitude parameters leading to good feasible designs. We present the algorithm, discuss details of its numerical implementation, and prove convergence to local minima of the objective function (here taken to be the intensity of the on-axis source in a "dark hole" region in the science focal plane). Finally, we present results showing application of the algorithm to both unobscured off-axis and obscured on-axis segmented telescope aperture designs. The application of the AFO algorithm to the coronagraph design problem has produced solutions which are capable of directly imaging planets in the habitable zone, provided end

  4. Parameters for HL-LHC aperture calculations and comparison with aperture measurements

    CERN Document Server

    Bruce, R; Fartoukh, S; Giovannozzi, M; Redaelli, S; Tomas, R; Wenninger, J

    2014-01-01

    When β∗ is squeezed to smaller values in the LHC, the beam size in the inner triplet increases so that the aperture risks to be exposed to unwanted beam losses. A 2D calculation model was used during the design stage to study the aperture margins, both there and at other potential bottlenecks. Based on assumptions on orbit and optics errors, as well as mechanical tolerances, it gives the available aperture in units of the RMS beam size, which can be compared with what can be protected by the collimation system. During the LHC Run I in 2010-2013, several of the error tolerances have been found smaller than the design assumptions. Furthermore, the aperture has been measured with beam several times and the results are compatible with a very well aligned machine, with results close to the design values. In this report, we therefore review the assumptions in the model and propose an updated set of input parameters to be used for aperture calculations at top energy in HL-LHC. The new parameter set is based on th...

  5. Filled aperture concepts for the Terrestrial Planet Finder

    Science.gov (United States)

    Ridgway, Stephen T.

    2003-02-01

    Filled aperture telescopes can deliver a real, high Strehl image which is well suited for discrimination of faint planets in the vicinity of bright stars and against an extended exo-zodiacal light. A filled aperture offers a rich variety of PSF control and diffraction suppression techniques. Filled apertures are under consideration for a wide spectral range, including visible and thermal-IR, each of which offers a significant selection of biomarker molecular bands. A filled aperture visible TPF may be simpler in several respects than a thermal-IR nuller. The required aperture size (or baseline) is much smaller, and no cryogenic systems are required. A filled aperture TPF would look and act like a normal telescope - vendors and users alike would be comfortable with its design and operation. Filled aperture telescopes pose significant challenges in production of large primary mirrors, and in very stringent wavefront requirements. Stability of the wavefront control, and hence of the PSF, is a major issue for filled aperture systems. Several groups have concluded that these and other issues can be resolved, and that filled aperture options are competitive for a TPF precursor and/or for the full TPF mission. Ball, Boeing-SVS and TRW have recently returned architecture reviews on filled aperture TPF concepts. In this paper, I will review some of the major considerations underlying these filled aperture concepts, and suggest key issues in a TPF Buyers Guide.

  6. Lightweight Structures Utilizing CNFs, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — AxNano proposes a novel method for producing robust, high-volume, cost-effective carbon fibers in support of next-generation materials for structural composite space...

  7. Lightweight cordierite–mullite refractories with low coefficients of ...

    Indian Academy of Sciences (India)

    of thermal conductivity and high mechanical properties ... compositions and microstructures of lightweight refractories were measured by X-ray .... of matrices were determined by calibration with EDAX ZAF .... Guzman I Ya 2003 Glass Ceram.

  8. Ontology learning from interpretations in lightweight description logics

    CSIR Research Space (South Africa)

    Klarman, S

    2015-08-01

    Full Text Available International Conference on Inductive Logic programming (ILP), Kyoto, Japan, 20-22 August 2015 Ontology Learning from Interpretations in Lightweight Description Logics Szymon Klarman1 and Katarina Britz2 1 Department of Computer Science, Brunel...

  9. Mechanical Properties of Steel Fiber Reinforced all Lightweight Aggregate Concrete

    Science.gov (United States)

    Yang, Y. M.; Li, J. Y.; Zhen, Y.; Nie, Y. N.; Dong, W. L.

    2018-05-01

    In order to study the basic mechanical properties and failure characteristics of all lightweight aggregate concrete with different volume of steel fiber (0%, 1%, 2%), shale ceramsite is used as light coarse aggregate. The shale sand is made of light fine aggregate and mixed with different volume of steel fiber, and the mix proportion design of all lightweight aggregate concrete is carried out. The cubic compressive strength, axial compressive strength, flexural strength, splitting strength and modulus of elasticity of steel fiber all lightweight aggregate concrete were studied. Test results show that the incorporation of steel fiber can restrict the cracking of concrete, improve crack resistance; at the same time, it shows good plastic deformation ability and failure morphology. It lays a theoretical foundation for further research on the application of all lightweight aggregate concrete in structural systems.

  10. Durability of lightweight concrete : Phase I : concrete temperature study.

    Science.gov (United States)

    1968-08-01

    This report describes a study conducted to determine the temperature gradient throughout the depth of a six inch concrete bridge deck. The bridge deck selected for study was constructed using lightweight concrete for the center spans and sand and gra...

  11. Annotating Evidence Based Clinical Guidelines : A Lightweight Ontology

    NARCIS (Netherlands)

    Hoekstra, R.; de Waard, A.; Vdovjak, R.; Paschke, A.; Burger, A.; Romano, P.; Marshall, M.S.; Splendiani, A.

    2012-01-01

    This paper describes a lightweight ontology for representing annotations of declarative evidence based clinical guidelines. We present the motivation and requirements for this representation, based on an analysis of several guidelines. The ontology provides the means to connect clinical questions

  12. Lightweight geopolymer composites as structural elements with improved insulation capacity

    Directory of Open Access Journals (Sweden)

    Kakali Glikeria

    2018-01-01

    Full Text Available This study concerns the development of lightweight fly ash based geopolymers which can be applied as alternatives to the traditional lightweight concrete. Different kinds of expanded polystyrene were used as lightweight agents. The results showed that lightweight geopolymers were successfully prepared, exhibiting compressive strength and density in the range 7.70 – 29.57 MPa and 0.97 – 1.57 g/cm3, respectively. The product containing 3% w/w of commercial expanded polystyrene possesses low thermal conductivity (0.16 W/mK combined with sufficient mechanical strengths (11 MPa, excellent stability and fire resistance while its water absorption is comparable to that of conventional construction materials (cement mortars, concrete.

  13. Feasibility Study on Manufacturing Lightweight Aggregates from Water Purification Sludge

    Science.gov (United States)

    Peng, Ching-Fang; Chen, How-Ji

    2018-02-01

    This study mainly discussed the feasibility of manufacturing lightweight aggregates from water purification sludge in Taiwan. They were analysed for the physical and chemical composition before the sintering test for lightweight aggregates in a laboratory. Then the physical and mechanical properties of the synthesized aggregates were assessed. The result showed that the chemical composition of sludge in the water purification plants was within the appropriate range for manufacturing lightweight aggregate as proposed in the literature. The sintering test demonstrated that the particle density of aggregates from the ten types of water purification sludge were mostly less than 1.8 g/cm3. In addition, the dry unit weight, the organic impurity, the ignition loss, and other characteristics of synthesized aggregates met the requirement of CNS standards, while its water absorption and crushing strength also fulfilled the general commercial specifications. Therefore, reclamation of water purification sludge for production of lightweight aggregate is indeed feasible.

  14. The use of spent glauconite in lightweight aggregate production

    OpenAIRE

    Franus, Wojciech; Franus, Małgorzata; Latosińska, Jolanta; Wójcik, Rafał

    2011-01-01

    The presented work has shown an application of spent glauconite bed after purification of wastewater for production of lightweight expanded clay aggregates. Sewage, from which it was removed Zn ions, came from technological line (zincworks) of Communication Equipment Factory „PZL” Świdnik. Spent glauconite bed was used as an additive in lightweight aggregate production which was obtained using plastic method by sintering, at temperature 1140 ºC and 1200 ºC, of spent glauconite amouts 10, 15, ...

  15. Acoustic Modeling of Lightweight Structures: A Literature Review

    Science.gov (United States)

    Yang, Shasha; Shen, Cheng

    2017-10-01

    This paper gives an overview of acoustic modeling for three kinds of typical lightweight structures including double-leaf plate system, stiffened single (or double) plate and porous material. Classical models are citied to provide frame work of theoretical modeling for acoustic property of lightweight structures; important research advances derived by our research group and other authors are introduced to describe the current state of art for acoustic research. Finally, remaining problems and future research directions are concluded and prospected briefly

  16. A new approach to dynamic aperture problems

    International Nuclear Information System (INIS)

    Schonfeld, J.F.

    1986-01-01

    We develop the theory of a passive magnetic system intended to suppress nonlinear orbit distortion in high-energy proton storage rings. The system is designed to immediately reduce 'Collins distortion functions,' which describe the size of nonlinear orbit distortion in first-order perturbation theory. Such a scheme could permit one significantly to decrease the physical aperture of a storage ring over most - but not necessarily all -of its length. This work was motivated by design needs of the proposed Superconducting Super Collider (SSC). (author)

  17. Parametric Beamformer for Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2006-01-01

    . The beamformer consists of a number of identical beamforming blocks, each processing data from several channels and producing part of the image. A number of these blocks can be accommodated in a modern field-programmable gate array device (FPGA), and a whole synthetic aperture system can be implemented using...... with 255 levels. A beamforming block uses input data from 4 elements and produces a set of 10 lines. Linear interpolation is used to implement sub-sample delays. The VHDL code for the beamformer has been synthesized for a Xilinx V4FX100 speed grade 11 FPGA, where it can operate at a maximum clock frequency...

  18. Lightweight SIP/SDP compression scheme (LSSCS)

    Science.gov (United States)

    Wu, Jian J.; Demetrescu, Cristian

    2001-10-01

    In UMTS new IP based services with tight delay constraints will be deployed over the W-CDMA air interface such as IP multimedia and interactive services. To integrate the wireline and wireless IP services, 3GPP standard forum adopted the Session Initiation Protocol (SIP) as the call control protocol for the UMTS Release 5, which will implement next generation, all IP networks for real-time QoS services. In the current form the SIP protocol is not suitable for wireless transmission due to its large message size which will need either a big radio pipe for transmission or it will take far much longer to transmit than the current GSM Call Control (CC) message sequence. In this paper we present a novel compression algorithm called Lightweight SIP/SDP Compression Scheme (LSSCS), which acts at the SIP application layer and therefore removes the information redundancy before it is sent to the network and transport layer. A binary octet-aligned header is added to the compressed SIP/SDP message before sending it to the network layer. The receiver uses this binary header as well as the pre-cached information to regenerate the original SIP/SDP message. The key features of the LSSCS compression scheme are presented in this paper along with implementation examples. It is shown that this compression algorithm makes SIP transmission efficient over the radio interface without losing the SIP generality and flexibility.

  19. Light-weight radioisotope heater impact tests

    International Nuclear Information System (INIS)

    Reimus, M.A.H.; Rinehart, G.H.; Herrera, A.

    1998-01-01

    The light-weight radioisotope heater unit (LWRHU) is a 238 PuO 2 -fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed 238 PuO 2 fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s

  20. Testnodes: a Lightweight node-testing infrastructure

    International Nuclear Information System (INIS)

    Fay, R; Bland, J

    2014-01-01

    A key aspect of ensuring optimum cluster reliability and productivity lies in keeping worker nodes in a healthy state. Testnodes is a lightweight node testing solution developed at Liverpool. While Nagios has been used locally for general monitoring of hosts and services, Testnodes is optimised to answer one question: is there any reason this node should not be accepting jobs? This tight focus enables Testnodes to inspect nodes frequently with minimal impact and provide a comprehensive and easily extended check with each inspection. On the server side, Testnodes, implemented in python, interoperates with the Torque batch server to control the nodes production status. Testnodes remotely and in parallel executes client-side test scripts and processes the return codes and output, adjusting the node's online/offline status accordingly to preserve the integrity of the overall batch system. Testnodes reports via log, email and Nagios, allowing a quick overview of node status to be reviewed and specific node issues to be identified and resolved quickly. This presentation will cover testnodes design and implementation, together with the results of its use in production at Liverpool, and future development plans.

  1. Lightweight autonomous chemical identification system (LACIS)

    Science.gov (United States)

    Lozos, George; Lin, Hai; Burch, Timothy

    2012-06-01

    Smiths Detection and Intelligent Optical Systems have developed prototypes for the Lightweight Autonomous Chemical Identification System (LACIS) for the US Department of Homeland Security. LACIS is to be a handheld detection system for Chemical Warfare Agents (CWAs) and Toxic Industrial Chemicals (TICs). LACIS is designed to have a low limit of detection and rapid response time for use by emergency responders and could allow determination of areas having dangerous concentration levels and if protective garments will be required. Procedures for protection of responders from hazardous materials incidents require the use of protective equipment until such time as the hazard can be assessed. Such accurate analysis can accelerate operations and increase effectiveness. LACIS is to be an improved point detector employing novel CBRNE detection modalities that includes a militaryproven ruggedized ion mobility spectrometer (IMS) with an array of electro-resistive sensors to extend the range of chemical threats detected in a single device. It uses a novel sensor data fusion and threat classification architecture to interpret the independent sensor responses and provide robust detection at low levels in complex backgrounds with minimal false alarms. The performance of LACIS prototypes have been characterized in independent third party laboratory tests at the Battelle Memorial Institute (BMI, Columbus, OH) and indoor and outdoor field tests at the Nevada National Security Site (NNSS). LACIS prototypes will be entering operational assessment by key government emergency response groups to determine its capabilities versus requirements.

  2. Chlorinated drinking water for lightweight laying hens

    Directory of Open Access Journals (Sweden)

    A.F. Schneider

    Full Text Available ABSTRACT The study aimed to evaluate the effect of different levels of chlorine in drinking water of laying hens on zootechnical performance, eggs shell quality, hemogasometry levels and calcium content in tibia. 144 Hy-Line laying hens, 61 weeks old, were used distributed in 24 metabolism cages. They were subjected to water diets, for a period of 28 days, using sodium hypochlorite as a chlorine source in order to obtain the following concentrations: 5ppm (control, 20ppm, 50ppm, and 100ppm. Their performance was evaluated through water consumption, feed intake, egg production and weight, egg mass, feed conversion. Shell quality was measured by specific gravity. At the end of the experiment, arterial blood was collected for blood gas level assessment and a poultry of each replicate was sacrificed to obtain tibia and calcium content measurement. There was a water consumption reduction from 20ppm of chlorine and feed intake reduction in poultry receiving water with 100ppm of chlorine. The regression analysis showed that the higher the level of chlorine in water, the higher the reduction in consumption. There were no differences in egg production and weight, egg mass, feed conversion, specific gravity, tibia calcium content, and hemogasometry levels (hydrogenionic potential, carbon dioxide partial pressure, oxygen partial pressure, sodium, potassium, chloride, bicarbonate, carbon dioxide total concentration, anion gap and oxygen saturation. The use of levels above 5ppm of chlorine is not recommended in the water of lightweight laying hens.

  3. Warm Hydroforming of Lightweight Metal Sheets

    International Nuclear Information System (INIS)

    Aginagalde, A.; Orus, A.; Esnaola, J. A.; Torca, I.; Galdos, L.; Garcia, C.

    2007-01-01

    Hydroforming is well known in steel applications for automotive industry, where complicated shapes can be get with high strength to weight ratios. Nevertheless, the poor formability of light alloys at room temperature has limited the application of hydroforming technology for aluminum and magnesium parts. Increasing the temperature of these materials allows substantially greater elongation without fracture. Warm forming strategy is applied in conventional processes, such as rolling and forging, in order to get complex shapes, but still rare in hydroforming technology. This is the technical base of this research project: the development of the hydroforming process at warm working temperatures. The main tasks of the initial phases of the research were the material characterization, and the heated fluid and tooling system design and set up for warm hydroforming of lightweight alloys. Once these goals were accomplished the present paper shows the obtained results. The uniaxial tensile deformation of 5754H111, 6082-T6, 6082-O and AZ31B at the temperature range of 25 deg. C - 250 deg. C is presented as the output of the material characterization task. Both the system features and the results obtained for a bulge test geometry carried out with a warm hydroforming system are also presented. The selected alloys show an improvement in formability at the studied temperature range under both uniaxial and biaxial state of stress

  4. Abstracting audit data for lightweight intrusion detection

    KAUST Repository

    Wang, Wei

    2010-01-01

    High speed of processing massive audit data is crucial for an anomaly Intrusion Detection System (IDS) to achieve real-time performance during the detection. Abstracting audit data is a potential solution to improve the efficiency of data processing. In this work, we propose two strategies of data abstraction in order to build a lightweight detection model. The first strategy is exemplar extraction and the second is attribute abstraction. Two clustering algorithms, Affinity Propagation (AP) as well as traditional k-means, are employed to extract the exemplars, and Principal Component Analysis (PCA) is employed to abstract important attributes (a.k.a. features) from the audit data. Real HTTP traffic data collected in our institute as well as KDD 1999 data are used to validate the two strategies of data abstraction. The extensive test results show that the process of exemplar extraction significantly improves the detection efficiency and has a better detection performance than PCA in data abstraction. © 2010 Springer-Verlag.

  5. Experimental Study on Fatigue Performance of Foamed Lightweight Soil

    Science.gov (United States)

    Qiu, Youqiang; Yang, Ping; Li, Yongliang; Zhang, Liujun

    2017-12-01

    In order to study fatigue performance of foamed lightweight soil and forecast its fatigue life in the supporting project, on the base of preliminary tests, beam fatigue tests on foamed lightweight soil is conducted by using UTM-100 test system. Based on Weibull distribution and lognormal distribution, using the mathematical statistics method, fatigue equations of foamed lightweight soil are obtained. At the same time, according to the traffic load on real road surface of the supporting project, fatigue life of formed lightweight soil is analyzed and compared with the cumulative equivalent axle loads during the design period of the pavement. The results show that even the fatigue life of foamed lightweight soil has discrete property, the linear relationship between logarithmic fatigue life and stress ratio still performs well. Especially, the fatigue life of Weibull distribution is more close to that derived from the lognormal distribution, in the instance of 50% guarantee ratio. In addition, the results demonstrated that foamed lightweight soil as subgrade filler has good anti-fatigue performance, which can be further adopted by other projects in the similar research domain.

  6. Simultaneous beam sampling and aperture shape optimization for SPORT

    International Nuclear Information System (INIS)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei; Ye, Yinyu

    2015-01-01

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  7. Simultaneous beam sampling and aperture shape optimization for SPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei, E-mail: Lei@stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Ye, Yinyu [Department of Management Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-02-15

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  8. Simultaneous beam sampling and aperture shape optimization for SPORT.

    Science.gov (United States)

    Zarepisheh, Masoud; Li, Ruijiang; Ye, Yinyu; Xing, Lei

    2015-02-01

    Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and neck and a prostate case

  9. Wideband Low Side Lobe Aperture Coupled Patch Phased Array Antennas

    Science.gov (United States)

    Poduval, Dhruva

    Low profile printed antenna arrays with wide bandwidth, high gain, and low Side Lobe Level (SLL) are in great demand for current and future commercial and military communication systems and radar. Aperture coupled patch antennas have been proposed to obtain wide impedance bandwidths in the past. Aperture coupling is preferred particularly for phased arrays because of their advantage of integration to other active devices and circuits, e.g. phase shifters, power amplifiers, low noise amplifiers, mixers etc. However, when designing such arrays, the interplay between array performance characteristics, such as gain, side lobe level, back lobe level, mutual coupling etc. must be understood and optimized under multiple design constraints, e.g. substrate material properties and thicknesses, element to element spacing, and feed lines and their orientation and arrangements with respect to the antenna elements. The focus of this thesis is to investigate, design, and develop an aperture coupled patch array with wide operating bandwidth (30%), high gain (17.5 dBi), low side lobe level (20 dB), and high Forward to Backward (F/B) ratio (21.8 dB). The target frequency range is 2.4 to 3 GHz given its wide application in WLAN, LTE (Long Term Evolution) and other communication systems. Notwithstanding that the design concept can very well be adapted at other frequencies. Specifically, a 16 element, 4 by 4 planar microstrip patch array is designed using HFSS and experimentally developed and tested. Starting from mutual coupling minimization a corporate feeding scheme is designed to achieve the needed performance. To reduce the SLL the corporate feeding network is redesigned to obtain a specific amplitude taper. Studies are conducted to determine the optimum location for a metallic reflector under the feed line to improve the F/B. An experimental prototype of the antenna was built and tested validating and demonstrating the performance levels expected from simulation predictions

  10. Fractal apertures in waveguides, conducting screens and cavities analysis and design

    CERN Document Server

    Ghosh, Basudeb; Kartikeyan, M V

    2014-01-01

    This book deals with the design and analysis of fractal apertures in waveguides, conducting screens and cavities using numerical electromagnetics and field-solvers. The aim is to obtain design solutions with improved accuracy for a wide range of applications. To achieve this goal, a few diverse problems are considered. The book is organized with adequate space dedicated for the design and analysis of fractal apertures in waveguides, conducting screens, and cavities, microwave/millimeter wave applications followed by detailed case-study problems to infuse better insight and understanding of the subject. Finally, summaries and suggestions are given for future work. Fractal geometries were widely used in electromagnetics, specifically for antennas and frequency selective surfaces (FSS). The self-similarity of fractal geometry gives rise to a multiband response, whereas the  space-filling nature of the fractal geometries makes it an efficient element in antenna and FSS unit cell miniaturization. Until now, no e...

  11. Coded aperture optimization using Monte Carlo simulations

    International Nuclear Information System (INIS)

    Martineau, A.; Rocchisani, J.M.; Moretti, J.L.

    2010-01-01

    Coded apertures using Uniformly Redundant Arrays (URA) have been unsuccessfully evaluated for two-dimensional and three-dimensional imaging in Nuclear Medicine. The images reconstructed from coded projections contain artifacts and suffer from poor spatial resolution in the longitudinal direction. We introduce a Maximum-Likelihood Expectation-Maximization (MLEM) algorithm for three-dimensional coded aperture imaging which uses a projection matrix calculated by Monte Carlo simulations. The aim of the algorithm is to reduce artifacts and improve the three-dimensional spatial resolution in the reconstructed images. Firstly, we present the validation of GATE (Geant4 Application for Emission Tomography) for Monte Carlo simulations of a coded mask installed on a clinical gamma camera. The coded mask modelling was validated by comparison between experimental and simulated data in terms of energy spectra, sensitivity and spatial resolution. In the second part of the study, we use the validated model to calculate the projection matrix with Monte Carlo simulations. A three-dimensional thyroid phantom study was performed to compare the performance of the three-dimensional MLEM reconstruction with conventional correlation method. The results indicate that the artifacts are reduced and three-dimensional spatial resolution is improved with the Monte Carlo-based MLEM reconstruction.

  12. Beam focusing by aperture displacement in multiampere ion sources

    International Nuclear Information System (INIS)

    Stewart, L.D.; Kim, J.; Matsuda, S.

    1975-05-01

    Results are given of an experimental study of beam focusing by aperture displacement (Δx) in duoPIGatron ion sources. Measurements with a single aperture, accel-decel electrode geometry show that the beam deflection angle is linear with Δx/z for the round aperture and with Δx/z* 2 for the slit aperture where z and z* are respectively the extraction gap distance and the effective gap distance. Applying the result of the single aperture study to the multiaperture, duoPIGatron sources, it was possible to increase the neutral beam injection power to the ORMAK plasma by approximately 40 percent. Also presented are discussion and comparison of other work on the effect of aperture displacement on beam deflection. (U.S.)

  13. Measurements of pore-scale flow through apertures

    Energy Technology Data Exchange (ETDEWEB)

    Chojnicki, Kirsten [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Pore-scale aperture effects on flow in pore networks was studied in the laboratory to provide a parameterization for use in transport models. Four cases were considered: regular and irregular pillar/pore alignment with and without an aperture. The velocity field of each case was measured and simulated, providing quantitatively comparable results. Two aperture effect parameterizations were considered: permeability and transmission. Permeability values varied by an order of magnitude between the cases with and without apertures. However, transmission did not correlate with permeability. Despite having much greater permeability the regular aperture case permitted less transmission than the regular case. Moreover, both irregular cases had greater transmission than the regular cases, a difference not supported by the permeabilities. Overall, these findings suggest that pore-scale aperture effects on flow though a pore-network may not be adequately captured by properties such as permeability for applications that are interested in determining particle transport volume and timing.

  14. Dynamic aperture of NR-2000 in the work regime with a small radiation emittance

    International Nuclear Information System (INIS)

    Zelinskij, A.Yu.; Karnaukhov, I.M.; Kononenko, S.G.; Tarasenko, A.S.

    1991-01-01

    NR-2000 is an electron storage ring installation with 6-pole magnets compensating its chromatism. The results of NR-2000 dynamic aperture numerical modelling in 6-dimension space are given. Perturbation of the equilibrium orbit and that of magnetic field up to the third order of magnitude were taken into consideration. Calculations were made according to DeCA programme. 7 refs.; 5 figs. (author)

  15. Numerical simulation of microwave pulse coupling into the rectangular cavity with aperture arrays

    International Nuclear Information System (INIS)

    Li Rui; Yang Yiming; Qian Baoliang

    2008-01-01

    In this paper, the finite-difference time-domain (FDTD) algorithm is employed to simulate microwave pulse coupling into the rectangular cavity with aperture arrays. In the case in which the long-side of the slot in aperture arrays is perpendicular to the incident electrical field, and the electrical distribution of each center of slot in the aperture arrays in the process of microwave pulse coupling into the rectangular cavity with aperture arrays is analyzed in detail. We find that the effect of field enhancement of the slot in the middle of all the slots which distribute in the direction parallel to the incident electrical field is minimum and increases in turn from the middle to both sides symmetrically. We also find that the effect of field enhancement of the slot in the middle of all the slots which distribute in the direction perpendicular to the incident electrical field is maximum and decreases in turn from the middle to both sides symmetrically. In the same time, we investigate the factors that influence the effect of field enhancement of the center of each slot and the coupling electrical distribution in the cavity, including the number of slots and the spacing between slots. (authors)

  16. Position measurement of the direct drive motor of Large Aperture Telescope

    Science.gov (United States)

    Li, Ying; Wang, Daxing

    2010-07-01

    Along with the development of space and astronomy science, production of large aperture telescope and super large aperture telescope will definitely become the trend. It's one of methods to solve precise drive of large aperture telescope using direct drive technology unified designed of electricity and magnetism structure. A direct drive precise rotary table with diameter of 2.5 meters researched and produced by us is a typical mechanical & electrical integration design. This paper mainly introduces position measurement control system of direct drive motor. In design of this motor, position measurement control system requires having high resolution, and precisely aligning the position of rotor shaft and making measurement, meanwhile transferring position information to position reversing information corresponding to needed motor pole number. This system has chosen high precision metal band coder and absolute type coder, processing information of coders, and has sent 32-bit RISC CPU making software processing, and gained high resolution composite coder. The paper gives relevant laboratory test results at the end, indicating the position measurement can apply to large aperture telescope control system. This project is subsidized by Chinese National Natural Science Funds (10833004).

  17. Collarless, close-in, shaped iron aperture designs for the SSC [Superconducting Super Collider] dipole

    International Nuclear Information System (INIS)

    Gupta, R.C.; Morgan, G.H.

    1989-01-01

    The nominal-design SSC (Superconducting Super Collider) dipole encloses the coil in an iron yoke having a circular aperture. The radial gap between the coil and the iron is about 15 mm to provide space for a strong annular collar around the coil, and also to reduce the effects of iron saturation on central field harmonics. The 15 mm gap also reduces the desirable dipole field contributed by the iron. The present paper gives a coil and aperture configuration in which the gap is reduced to 5 mm at the midplane, in which the aperture is shaped to reduce the unwanted effects of iron saturation. The transfer function is increased about 5% at 6.6 Tesla and the unwanted harmonics are within SSC tolerances at all field levels. These designs would require that the yoke and containment vessel absorb the stresses due to assembly and magnetic forces. A short magnet is being built with a close-in shaped iron aperture and existing coil geometry to assess the benefits of this concept. 7 refs., 3 figs., 6 tabs

  18. Field measurements for low-aperture magnetic elements

    International Nuclear Information System (INIS)

    Mikhajlichenko, A.A.

    1989-01-01

    The method of the field measurements with help of bismuth wire in low aperture magnetic elements is revised. The quadrupole with permanent magnets was tested. It has aperture diameter about 4 mm and length 40 mm. Gradient about 38 kOe/cm was measured. The accuracy of the magnetic axis position definition is better than 1 μm. This method is a good kandidate for linear colider low aperture magnetic elements measurements. 7 refs.; 6 figs

  19. Extended Aperture Photometry of K2 RR Lyrae stars

    Directory of Open Access Journals (Sweden)

    Plachy Emese

    2017-01-01

    Full Text Available We present the method of the Extended Aperture Photometry (EAP that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC pipeline applied on the automated Single Aperture Photometry (SAP and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP data.

  20. Extended Aperture Photometry of K2 RR Lyrae stars

    Science.gov (United States)

    Plachy, Emese; Klagyivik, Péter; Molnár, László; Sódor, Ádám; Szabó, Róbert

    2017-10-01

    We present the method of the Extended Aperture Photometry (EAP) that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC) pipeline applied on the automated Single Aperture Photometry (SAP) and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP) data.

  1. Mask design and fabrication in coded aperture imaging

    International Nuclear Information System (INIS)

    Shutler, Paul M.E.; Springham, Stuart V.; Talebitaher, Alireza

    2013-01-01

    We introduce the new concept of a row-spaced mask, where a number of blank rows are interposed between every pair of adjacent rows of holes of a conventional cyclic difference set based coded mask. At the cost of a small loss in signal-to-noise ratio, this can substantially reduce the number of holes required to image extended sources, at the same time increasing mask strength uniformly across the aperture, as well as making the mask automatically self-supporting. We also show that the Finger and Prince construction can be used to wrap any cyclic difference set onto a two-dimensional mask, regardless of the number of its pixels. We use this construction to validate by means of numerical simulations not only the performance of row-spaced masks, but also the pixel padding technique introduced by in ’t Zand. Finally, we provide a computer program CDSGEN.EXE which, on a fast modern computer and for any Singer set of practical size and open fraction, generates the corresponding pattern of holes in seconds

  2. Genetic algorithm enhanced by machine learning in dynamic aperture optimization

    Science.gov (United States)

    Li, Yongjun; Cheng, Weixing; Yu, Li Hua; Rainer, Robert

    2018-05-01

    With the aid of machine learning techniques, the genetic algorithm has been enhanced and applied to the multi-objective optimization problem presented by the dynamic aperture of the National Synchrotron Light Source II (NSLS-II) Storage Ring. During the evolution processes employed by the genetic algorithm, the population is classified into different clusters in the search space. The clusters with top average fitness are given "elite" status. Intervention on the population is implemented by repopulating some potentially competitive candidates based on the experience learned from the accumulated data. These candidates replace randomly selected candidates among the original data pool. The average fitness of the population is therefore improved while diversity is not lost. Maintaining diversity ensures that the optimization is global rather than local. The quality of the population increases and produces more competitive descendants accelerating the evolution process significantly. When identifying the distribution of optimal candidates, they appear to be located in isolated islands within the search space. Some of these optimal candidates have been experimentally confirmed at the NSLS-II storage ring. The machine learning techniques that exploit the genetic algorithm can also be used in other population-based optimization problems such as particle swarm algorithm.

  3. Experiment in Onboard Synthetic Aperture Radar Data Processing

    Science.gov (United States)

    Holland, Matthew

    2011-01-01

    Single event upsets (SEUs) are a threat to any computing system running on hardware that has not been physically radiation hardened. In addition to mandating the use of performance-limited, hardened heritage equipment, prior techniques for dealing with the SEU problem often involved hardware-based error detection and correction (EDAC). With limited computing resources, software- based EDAC, or any more elaborate recovery methods, were often not feasible. Synthetic aperture radars (SARs), when operated in the space environment, are interesting due to their relevance to NASAs objectives, but problematic in the sense of producing prodigious amounts of raw data. Prior implementations of the SAR data processing algorithm have been too slow, too computationally intensive, and require too much application memory for onboard execution to be a realistic option when using the type of heritage processing technology described above. This standard C-language implementation of SAR data processing is distributed over many cores of a Tilera Multicore Processor, and employs novel Radiation Hardening by Software (RHBS) techniques designed to protect the component processes (one per core) and their shared application memory from the sort of SEUs expected in the space environment. The source code includes calls to Tilera APIs, and a specialized Tilera compiler is required to produce a Tilera executable. The compiled application reads input data describing the position and orientation of a radar platform, as well as its radar-burst data, over time and writes out processed data in a form that is useful for analysis of the radar observations.

  4. The Affordable Pre-Finishing of Silicon Carbide for Optical Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Large aperture, lightweight optical mirror technologies are critical for the future of lightweight telescopes and their attendant missions to explore the planets in...

  5. Avian Feathers: An Examination of Lightweight Resilience and Bioinspired Designs

    Science.gov (United States)

    Sullivan, Tarah Naoe

    In bird flight, the majority of the wing surface consists of highly refined and hierarchically organized beta-keratinous feathers. Thus, flight feathers contain ingenious combinations of components that optimize lift, stiffness, aerodynamics, and damage resistance. Their design involves two main parts: a central shaft which prescribes stiffness and lateral vanes that allow for the capture of air. Within the feather vane, barbs branch from the shaft and barbules branch from barbs, forming a flat surface and ensuring lift. Microhooks at the end of barbules hold barbs tightly together, providing a close-knit, unified structure and enabling repair of the vane through the reattachment of un-hooked junctions. In this dissertation, unique aspects of feather architecture are explored to uncover principles translatable to the design of modern aerospace materials and structures. Specifically, understudied aspects of the feather's lightweight yet resilient properties are investigated. This research has revealed several novel characteristics of the feather. Allometric scaling relationships are developed linking the geometry of a bird's wing components to its flight characteristics and total mass. Barbule spacing within the feather vane is found to be 8-16 microm for birds ranging from 0.02-11 kg. Additionally, it is discovered that strength is recovered with the shape recovery property of feathers, and a mechanism for this phenomenon is proposed. Barbule adhesion within the vane is found to prevent barbs from twisting in flexure, maintaining the vane's stiffness, and the extent to which unzipping these connections affects the feather's ability to capture air is related to barb shape. Directional permeability of the feather vane is experimentally confirmed and related to the intricate microstructure of barbules. Lastly, the exceptional architecture of the feather motivated the design of novel bioinspired structures with tailored and unique properties. The avian feather serves

  6. Clinical evaluation of synthetic aperture sequential beamforming

    DEFF Research Database (Denmark)

    Hansen, Peter Møller; Hemmsen, Martin Christian; Lange, Theis

    2012-01-01

    In this study clinically relevant ultrasound images generated with synthetic aperture sequential beamforming (SASB) is compared to images generated with a conventional technique. The advantage of SASB is the ability to produce high resolution ultrasound images with a high frame rate and at the same...... time massively reduce the amount of generated data. SASB was implemented in a system consisting of a conventional ultrasound scanner connected to a PC via a research interface. This setup enables simultaneous recording with both SASB and conventional technique. Eighteen volunteers were ultrasound...... scanned abdominally, and 84 sequence pairs were recorded. Each sequence pair consists of two simultaneous recordings of the same anatomical location with SASB and conventional B-mode imaging. The images were evaluated in terms of spatial resolution, contrast, unwanted artifacts, and penetration depth...

  7. Optimization of Spatiotemporal Apertures in Channel Sounding

    DEFF Research Database (Denmark)

    Pedersen, Troels; Pedersen, Claus; Yin, Xuefeng

    2008-01-01

    a spatiotemporal model which can describe parallel as well as switched sounding systems. The proposed model is applicable for arbitrary layouts of the spatial arrays. To simplify the derivations we investigate the special case of linear spatial arrays. However, the results obtained for linear arrays can......In this paper we investigate the impact of the spatio-temporal aperture of a channel sounding system equipped with antenna arrays at the transmitter and receiver on the accuracy of joint estimation of Doppler frequency and bi-direction. The contribution of this work is three-fold. Firstly, we state...... be generalized to arbitrary arrays. Secondly, we give the necessary and sufficient conditions for a spatio-temporal array to yield the minimum Cramér-Rao lower bound in the single-path case and Bayesian Cramér-Rao Lower Bound in the multipath case. The obtained conditions amount to an orthogonality condition...

  8. Tissue Harmonic Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Rasmussen, Joachim; Jensen, Jørgen Arendt

    2014-01-01

    Synthetic aperture sequential beamforming (SASB) and tissue har- monic imaging (THI) are combined to improve the image quality of medical ultrasound imaging. The technique is evaluated in a compar- ative study against dynamic receive focusing (DRF). The objective is to investigate if SASB combined...... with THI improves the image qual- ity compared to DRF-THI. The major benet of SASB is a reduced bandwidth between the probe and processing unit. A BK Medical 2202 Ultraview ultrasound scanner was used to acquire beamformed RF data for oine evaluation. The acquisition was made interleaved between methods......, and data were recorded with and without pulse inversion for tissue harmonic imaging. Data were acquired using a Sound Technol- ogy 192 element convex array transducer from both a wire phantom and a tissue mimicking phantom to investigate spatial resolution and pen- etration. In-vivo scans were also...

  9. Defocus morphing in real aperture images.

    Science.gov (United States)

    Chaudhuri, Subhasis

    2005-11-01

    A new concept called defocus morphing in real aperture images is introduced. View morphing is an existing example of shape-preserving image morphing based on the motion cue. It is proved that images can also be morphed based on the depth-related defocus cue. This illustrates that the morphing operation is not necessarily a geometric process alone; one can also perform a photometry-based morphing wherein the shape information is implicitly buried in the image intensity field. A theoretical understanding of the defocus morphing process is presented. It is shown mathematically that, given two observations of a three-dimensional scene for different camera parameter settings, we can obtain a virtual observation for any camera parameter setting through a simple nonlinear combination of these observations.

  10. Common aperture multispectral spotter camera: Spectro XR

    Science.gov (United States)

    Petrushevsky, Vladimir; Freiman, Dov; Diamant, Idan; Giladi, Shira; Leibovich, Maor

    2017-10-01

    The Spectro XRTM is an advanced color/NIR/SWIR/MWIR 16'' payload recently developed by Elbit Systems / ELOP. The payload's primary sensor is a spotter camera with common 7'' aperture. The sensor suite includes also MWIR zoom, EO zoom, laser designator or rangefinder, laser pointer / illuminator and laser spot tracker. Rigid structure, vibration damping and 4-axes gimbals enable high level of line-of-sight stabilization. The payload's list of features include multi-target video tracker, precise boresight, strap-on IMU, embedded moving map, geodetic calculations suite, and image fusion. The paper describes main technical characteristics of the spotter camera. Visible-quality, all-metal front catadioptric telescope maintains optical performance in wide range of environmental conditions. High-efficiency coatings separate the incoming light into EO, SWIR and MWIR band channels. Both EO and SWIR bands have dual FOV and 3 spectral filters each. Several variants of focal plane array formats are supported. The common aperture design facilitates superior DRI performance in EO and SWIR, in comparison to the conventionally configured payloads. Special spectral calibration and color correction extend the effective range of color imaging. An advanced CMOS FPA and low F-number of the optics facilitate low light performance. SWIR band provides further atmospheric penetration, as well as see-spot capability at especially long ranges, due to asynchronous pulse detection. MWIR band has good sharpness in the entire field-of-view and (with full HD FPA) delivers amount of detail far exceeding one of VGA-equipped FLIRs. The Spectro XR offers level of performance typically associated with larger and heavier payloads.

  11. Production of lightweight refractory material by hydrothermal process

    International Nuclear Information System (INIS)

    Sulejmani, Ramiz B.

    2002-01-01

    Many different processes of production of lightweight refractories are well known over the World. Traditional production of lightweight refractories is by addition of combustibles or by a special frothing process. This work is concerned with hydrothermal of lightweight refractories from rice husk ash. The rice husk ash, used in present investigations were from Kocani region, R. Macedonia. The chemical analysis of the rice husk ash shows that it contains 91,8 - 93,7% SiO 2 and some alkaline and alkaline earth oxides. Microscopic and X - ray diffraction examinations of the rice husk ash have shown that it is composed of cristobalite, tridimite and amorphous silica. The composition of the mixture for lightweight refractory brick production is 93,4% rice husk ash and 6,6% Ca(OH) 2 . The mixtures were well mixed, moistened and pressed at 5 - 10 MPa. The hydrothermal reactions between calcium hydroxide and rice husk ash over the temperature range 80 - 160 o C were investigated. The period of autoclave treatment was from 2 to 72 h. After the hydrothermal treatment of the samples, the mineralogical composition, bulk density, density, cold crushing strength, porosity, refractoriness and thermal expansion were examined. Analysing the properties of the obtained samples it can be concluded that from rice husk ash and calcium hydroxide under hydrothermal condition it is possible to obtain lightweight acid refractory material with high quality.(Author)

  12. Wide-swath Shared Aperture Cloud Radar

    Data.gov (United States)

    National Aeronautics and Space Administration — The Goddard Space Flight Center (GSFC) and Northrop Grumman Electronic Systems (NGES) seek to advance key enabling technologies for next generation multi-frequency...

  13. Forming mandrels for making lightweight x-ray mirrors

    Science.gov (United States)

    Blake, Peter N.; Saha, Timo; Zhang, William W.; O'Dell, Stephen; Kester, Thomas; Jones, William

    2011-09-01

    Future x-ray astronomical missions, similar to the proposed International X-ray Observatory (IXO), will utilize replicated mirrors to reduce both mass and production costs. Accurately figured and measured molds (called mandrels) - on which the mirror substrates are thermally formed, replicating the surface of the mandrels - are essential to enable these missions. The Optics Branches of the Goddard Space Flight Center (GSFC) and Marshall Space Flight Center (MSFC) have developed fabrication processes along with metrologies that yield high-precision mandrels; and through the SBIR program, they encourage small businesses to attack parts of the remaining problems. The Goddard full-aperture mandrel polisher (the MPM-500) has been developed to a level where mandrel surfaces match the 1.5 arcsec HPD level allocation in a 5 arcsec telescope program. This paper reviews this current technology and describes a pilot program to design a suite of machine tools and process parameters capable of producing many hundreds of these precision objects. A major challenge is to keep mid-spatial frequency errors below 2 nm rms - a severe specification; but we must also note the factors which work to our advantage: e.g., how the figure departs from a pure cone by only one micron, and how the demanding figure specifications which apply in the axial direction are relaxed by an order of magnitude in the azimuthal. Careful study of other large optical fabrication programs in the light of these challenges and advantages has yielded a realistic plan for the economical production of mandrels that meet program requirements in both surface and quantity.

  14. Lightweight, Composite Cryogenic Tank Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcosm has developed and qualified strong, all-composite LOX tanks for launch vehicles. Our new 42-inch diameter tank design weighs 486 lbs and burst without...

  15. Lightweight Materials and Structures (LMS): Inflatable Structures

    Data.gov (United States)

    National Aeronautics and Space Administration —  Current inflatable structures are designed on the restraint layer’s short term properties with a Factor of Safety of 4 due to lack of long-term data on structural...

  16. Synthetic aperture design for increased SAR image rate

    Science.gov (United States)

    Bielek, Timothy P [Albuquerque, NM; Thompson, Douglas G [Albuqerque, NM; Walker, Bruce C [Albuquerque, NM

    2009-03-03

    High resolution SAR images of a target scene at near video rates can be produced by using overlapped, but nevertheless, full-size synthetic apertures. The SAR images, which respectively correspond to the apertures, can be analyzed in sequence to permit detection of movement in the target scene.

  17. Growth Adapted Tensegrity Structures - A New Calculus for the Space Economy

    Data.gov (United States)

    National Aeronautics and Space Administration — We describe a novel approach to create and engineer an economically viable space habitat development technology, for deployment of a lightweight tensegrity habitat...

  18. Lightweight acoustic treatments for aerospace applications

    Science.gov (United States)

    Naify, Christina Jeanne

    2011-12-01

    Increase in the use of composites for aerospace applications has the benefit of decreased structural weight, but at the cost of decreased acoustic performance. Stiff, lightweight structures (such as composites) are traditionally not ideal for acoustic insulation applications because of high transmission loss at low frequencies. A need has thus arisen for effective sound insulation materials for aerospace and automotive applications with low weight addition. Current approaches, such as the addition of mass law dominated materials (foams) also perform poorly when scaled to small thickness and low density. In this dissertation, methods which reduce sound transmission without adding significant weight are investigated. The methods presented are intended to be integrated into currently used lightweight structures such as honeycomb sandwich panels and to cover a wide range of frequencies. Layering gasses of differing acoustic impedances on a panel substantially reduced the amount of sound energy transmitted through the panel with respect to the panel alone or an equivalent-thickness single species gas layer. The additional transmission loss derives from successive impedance mismatches at the interfaces between gas layers and the resulting inefficient energy transfer. Attachment of additional gas layers increased the transmission loss (TL) by as much as 17 dB at high (>1 kHz) frequencies. The location and ordering of the gasses with respect to the panel were important factors in determining the magnitude of the total TL. Theoretical analysis using a transfer matrix method was used to calculate the frequency dependence of sound transmission for the different configurations tested. The method accurately predicted the relative increases in TL observed with the addition of different gas layer configurations. To address low-frequency sound insulation, membrane-type locally resonant acoustic materials (LRAM) were fabricated, characterized, and analyzed to understand their

  19. Flexible Graphene-Based Energy Storage Devices for Space Application

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this project is to develop a graphene-based battery/ultra-capacitor prototype that is flexible, thin, lightweight, durable, low cost, and safe and...

  20. Durability of Geopolymer Lightweight Concrete Infilled LECA in Seawater Exposure

    Science.gov (United States)

    Razak, R. A.; Abdullah, M. M. A. B.; Yahya, Z.; Hamid, M. S. A.

    2017-11-01

    This paper describes a development of lightweight concrete using lightweight expanded clay aggregate (LECA) in fly ash (FA) based geopolymer immersed in seawater. The objective of this research is to compare the performance of geopolymer concrete (GPC) with ordinary Portland cement (OPC) concrete infilled lightweight expanded clay aggregate (LECA) in seawater exposure. Geopolymer concrete is produced by using alkaline activator to activate the raw material, FA. The highest compressive strength of this study is 42.0 MPa at 28 days and 49.8 MPa at 60 days. The density for this concrete is in the range of 1580 kg/m3 to 1660 kg/m3. The result for water absorption is in the range of 6.82% to 14.72%. However, the test results of weight loss is in the range between 0.30% to 0.43%.

  1. Light-weight Mutual Authentication with Non-repudiation

    Directory of Open Access Journals (Sweden)

    V. Clupek

    2018-04-01

    Full Text Available In this paper, we focused on a problem of authentication on low-cost devices. We have proposed a new light-weight protocol for mutual authentication of communication entities with non-repudiation of realized events. The protocol is simple and suitable for implementation on low-cost devices. Non-repudiation of realized events is achieved by involving a Trusted Third Party (TTP to the communication. The proposed protocol uses only an appropriate lightweight hash function and pre-shared secret data. Security of the proposed protocol was verified by the BAN (Burrows-Abadi-Needham logic.

  2. 47 CFR 25.134 - Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal...

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal (CSAT) networks. 25.134 Section 25.134 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS...

  3. High resolution earth observation from geostationary orbit by optical aperture synthesys

    Science.gov (United States)

    Mesrine, M.; Thomas, E.; Garin, S.; Blanc, P.; Alis, C.; Cassaing, F.; Laubier, D.

    2017-11-01

    In this paper, we describe Optical Aperture Synthesis (OAS) imaging instrument concepts studied by Alcatel Alenia Space under a CNES R&T contract in term of technical feasibility. First, the methodology to select the aperture configuration is proposed, based on the definition and quantification of image quality criteria adapted to an OAS instrument for direct imaging of extended objects. The following section presents, for each interferometer type (Michelson and Fizeau), the corresponding optical configurations compatible with a large field of view from GEO orbit. These optical concepts take into account the constraints imposed by the foreseen resolution and the implementation of the co-phasing functions. The fourth section is dedicated to the analysis of the co-phasing methodologies, from the configuration deployment to the fine stabilization during observation. Finally, we present a trade-off analysis allowing to select the concept wrt mission specification and constraints related to instrument accommodation under launcher shroud and in-orbit deployment.

  4. X-ray lenses with large aperture

    International Nuclear Information System (INIS)

    Simon, Markus

    2010-01-01

    Up to now, most X-ray imaging setups are based on absorption contrast imaging. There is a demand for focused X-rays in many X-ray analysis applications, either to increase the resolution of an imaging system, or, to reduce the time effort of an experiment through higher photon flux. For photon energies higher than 15 keV refractive X-ray optics are more efficient in comparison to non-refractive X-ray optics. The aim of this work was to develop X-ray lenses with large apertures and high transparency. By increasing the number of refracting surfaces while removing unnecessary lens material such lenses have been developed. Utilizing this approach the overall beam deflection angle is large with respect to the lens material it propagates through and so the transparency of the lens is increased. Within this work, X-ray lenses consisting of several thousands of prisms with an edge length in the range of micrometers have been developed and fabricated by deep X-ray lithography. Deep X-ray lithography enables high precision microstrucures with smooth sidewalls and large aspect ratios. The aperture of high-transparency X-ray lenses made this way is greater than 1 mm. They are suitable for photon energies in the range of 8 keV to 24 keV and offer a focal width of smaller than 10 μm at a transparency of around 40%. Furthermore, rolled X-ray lenses have been developed, that are made out of a microstructured polyimide film, which is cut according to the requirements regarding focal length and photon energy. The microstructured film is fabricated by molding, using an anisotropically etched silicon wafer as molding tool. Its mean roughness is in the range of nanometers. The film features prismatic structures, its surface topology is similar to an asparagus field. The measured diameter of the point focus was 18 μm to 31 μm, the calculated opticla efficiency was 37%. Future work will concentrate on increasing the aspect ratio of Prism Lenses and on increasing the rolling accuracy

  5. Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

    Science.gov (United States)

    Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

    2006-01-01

    As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

  6. Crew Systems for Asteroid Exploration: Concepts for Lightweight & Low Volume EVA Systems

    Science.gov (United States)

    Mueller, Rob; Calle, Carlos; Mantovani, James

    2013-01-01

    This RFI response is targeting Area 5. Crew Systems for Asteroid Exploration: concepts for lightweight and low volume robotic and extra-vehicular activity (EVA) systems, such as space suits, tools, translation aids, stowage containers, and other equipment. The NASA KSC Surface Systems Office, Granular Mechanics and Regolith Operations (GMRO) Lab and the Electrostatics & Surface Physics Lab (ESPL) are dedicated to developing technologies for operating in regolith environments on target body surfaces. We have identified two technologies in our current portfolio that are highly relevant and useful for crews that will visit a re-directed asteroid in Cis-Lunar Space. Both technologies are at a high TRL of 5/6 and could be rapidly implemented in time for an ARM mission in this decade.

  7. Joint synthetic aperture radar plus ground moving target indicator from single-channel radar using compressive sensing

    Science.gov (United States)

    Thompson, Douglas; Hallquist, Aaron; Anderson, Hyrum

    2017-10-17

    The various embodiments presented herein relate to utilizing an operational single-channel radar to collect and process synthetic aperture radar (SAR) and ground moving target indicator (GMTI) imagery from a same set of radar returns. In an embodiment, data is collected by randomly staggering a slow-time pulse repetition interval (PRI) over a SAR aperture such that a number of transmitted pulses in the SAR aperture is preserved with respect to standard SAR, but many of the pulses are spaced very closely enabling movers (e.g., targets) to be resolved, wherein a relative velocity of the movers places them outside of the SAR ground patch. The various embodiments of image reconstruction can be based on compressed sensing inversion from undersampled data, which can be solved efficiently using such techniques as Bregman iteration. The various embodiments enable high-quality SAR reconstruction, and high-quality GMTI reconstruction from the same set of radar returns.

  8. Large Aperture "Photon Bucket" Optical Receiver Performance in High Background Environments

    Science.gov (United States)

    Vilnrotter, Victor A.; Hoppe, D.

    2011-01-01

    The potential development of large aperture groundbased "photon bucket" optical receivers for deep space communications, with acceptable performance even when pointing close to the sun, is receiving considerable attention. Sunlight scattered by the atmosphere becomes significant at micron wavelengths when pointing to a few degrees from the sun, even with the narrowest bandwidth optical filters. In addition, high quality optical apertures in the 10-30 meter range are costly and difficult to build with accurate surfaces to ensure narrow fields-of-view (FOV). One approach currently under consideration is to polish the aluminum reflector panels of large 34-meter microwave antennas to high reflectance, and accept the relatively large FOV generated by state-of-the-art polished aluminum panels with rms surface accuracies on the order of a few microns, corresponding to several-hundred micro-radian FOV, hence generating centimeter-diameter focused spots at the Cassegrain focus of 34-meter antennas. Assuming pulse-position modulation (PPM) and Poisson-distributed photon-counting detection, a "polished panel" photon-bucket receiver with large FOV will collect hundreds of background photons per PPM slot, along with comparable signal photons due to its large aperture. It is demonstrated that communications performance in terms of PPM symbol-error probability in high-background high-signal environments depends more strongly on signal than on background photons, implying that large increases in background energy can be compensated by a disproportionally small increase in signal energy. This surprising result suggests that large optical apertures with relatively poor surface quality may nevertheless provide acceptable performance for deep-space optical communications, potentially enabling the construction of cost-effective hybrid RF/optical receivers in the future.

  9. Strength properties of cement slurries with lightweights applied in oil and gas wells

    International Nuclear Information System (INIS)

    Bubnov, A S; Drilling Mud and Cement Slurry (Russian Federation))" data-affiliation=" (Head of Laboratory Drilling Mud and Cement Slurry (Russian Federation))" >Boyko, I A; Drilling Mud and Cement Slurry (Russian Federation))" data-affiliation=" (PhD, Engineer, Laboratory Drilling Mud and Cement Slurry (Russian Federation))" >Khorev, V S

    2015-01-01

    The article is focused on the cement stone strength properties resulted from lightweight cement slurries that meet GOST-1581-96 (state Standards) requirements. Exfoliated vermiculite, hollow aluminosilicate microspheres (HAMs), diatomite and perlite were used as lightweighting additives

  10. PTBS segmentation scheme for synthetic aperture radar

    Science.gov (United States)

    Friedland, Noah S.; Rothwell, Brian J.

    1995-07-01

    The Image Understanding Group at Martin Marietta Technologies in Denver, Colorado has developed a model-based synthetic aperture radar (SAR) automatic target recognition (ATR) system using an integrated resource architecture (IRA). IRA, an adaptive Markov random field (MRF) environment, utilizes information from image, model, and neighborhood resources to create a discrete, 2D feature-based world description (FBWD). The IRA FBWD features are peak, target, background and shadow (PTBS). These features have been shown to be very useful for target discrimination. The FBWD is used to accrue evidence over a model hypothesis set. This paper presents the PTBS segmentation process utilizing two IRA resources. The image resource (IR) provides generic (the physics of image formation) and specific (the given image input) information. The neighborhood resource (NR) provides domain knowledge of localized FBWD site behaviors. A simulated annealing optimization algorithm is used to construct a `most likely' PTBS state. Results on simulated imagery illustrate the power of this technique to correctly segment PTBS features, even when vehicle signatures are immersed in heavy background clutter. These segmentations also suppress sidelobe effects and delineate shadows.

  11. Experimental study on the effect of volcanic residue on the performance of recycled lightweight aggregate concrete

    Science.gov (United States)

    Xiao, Li-guang; Li, Ji-heng; Liu, Qing-shun

    2017-08-01

    Recycled lightweight aggregate concrete prepared with waste brick recycled light aggregate has high water absorption, large apparent density and poor frost resistance. The technical measures of regen-erating lightweight aggregate concrete with modified waste bricks from volcanic slag are put forward. The effects of volcanic slag on the properties of waste lightweight aggregate concrete were studied. The experi-mental results show that volcanic slag can significantly reduce the apparent density of recycled lightweight aggregate concrete and improve its frost resistance.

  12. Imaging with rotating slit apertures and rotating collimators

    International Nuclear Information System (INIS)

    Gindi, G.R.; Arendt, J.; Barrett, H.H.; Chiu, M.Y.; Ervin, A.; Giles, C.L.; Kujoory, M.A.; Miller, E.L.; Simpson, R.G.

    1982-01-01

    The statistical quality of conventional nuclear medical imagery is limited by the small signal collect through low-efficiency conventional apertures. Coded-aperture imaging overcomes this by employing a two-step process in which the object is first efficiently detected as an ''encoded'' form which does not resemble the object, and then filtered (or ''decoded'') to form an image. We present here the imaging properties of a class of time-modulated coded apertures which, unlike most coded apertures, encode projections of the object rather than the object itself. These coded apertures can reconstruct a volume object nontomographically, tomographically (one plane focused), or three-dimensionally. We describe a new decoding algorithm that reconstructs the object from its planar projections. Results of noise calculations are given, and the noise performance of these coded-aperture systems is compared to that of conventional counterparts. A hybrid slit-pinhole system which combines the imaging advantages of a rotating slit and a pinhole is described. A new scintillation detector which accurately measures the position of an event in one dimension only is presented, and its use in our coded-aperture system is outlined. Finally, results of imaging test objects and animals are given

  13. Imaging with rotating slit apertures and rotating collimators

    International Nuclear Information System (INIS)

    Gindi, G.R.; Arendt, J.; Barrett, H.H.; Chiu, M.Y.; Ervin, A.; Giles, C.L.; Kujoory, M.A.; Miller, E.L.; Simpson, R.G.

    1982-01-01

    The statistical quality of conventional nuclear medical imagery is limited by the small signal collected through low-efficiency conventional apertures. Coded-aperture imaging overcomes this by employing a two-step process in which the object is first efficiently detected as an encoded form which does not resemble the object, and then filtered (or decoded) to form an image. We present here the imaging properties of a class of time-modulated coded apertures which, unlike most coded apertures, encode projections of the object rather than the object itself. These coded apertures can reconstruct a volume object nontomographically, tomographically (one plane focused), or three-dimensionally. We describe a new decoding algorithm that reconstructs the object from its planar projections. Results of noise calculations are given, and the noise performance of these coded-aperture systems is compared to that of conventional counterparts. A hybrid slit-pinhole system which combines the imaging advantages of a rotating slit and a pinhole is described. A new scintillation detector which accurately measures the position of an event in one dimension only is presented, and its use in our coded-aperture system is outlined. Finally, results of imaging test objects and animals are given

  14. A lightweight portable, walk-in trap for catching vultures

    African Journals Online (AJOL)

    Two holes are drilled through the tubing and the piece of wood is attached to the tubing using 8.7 cm screws (Figure. 3). The location of the latch on the ... lightweight, walk-in trap, with door (shaded area) open, small black square shows location of gate latch. Figure 3. Close-up of gate latch. (photograph: David R. Barber).

  15. Design of Light-Weight High-Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Rui Feng

    2016-09-01

    Full Text Available High-entropy alloys (HEAs are a new class of solid-solution alloys that have attracted worldwide attention for their outstanding properties. Owing to the demand from transportation and defense industries, light-weight HEAs have also garnered widespread interest from scientists for use as potential structural materials. Great efforts have been made to study the phase-formation rules of HEAs to accelerate and refine the discovery process. In this paper, many proposed solid-solution phase-formation rules are assessed, based on a series of known and newly-designed light-weight HEAs. The results indicate that these empirical rules work for most compositions but also fail for several alloys. Light-weight HEAs often involve the additions of Al and/or Ti in great amounts, resulting in large negative enthalpies for forming solid-solution phases and/or intermetallic compounds. Accordingly, these empirical rules need to be modified with the new experimental data. In contrast, CALPHAD (acronym of the calculation of phase diagrams method is demonstrated to be an effective approach to predict the phase formation in HEAs as a function of composition and temperature. Future perspectives on the design of light-weight HEAs are discussed in light of CALPHAD modeling and physical metallurgy principles.

  16. LETOS -- A Lightweight Execution Tool for Operational Semantics

    NARCIS (Netherlands)

    Hartel, Pieter H.

    A lightweight tool is proposed to aid in the development of operational semantics. To use LETOS an operational semantics must be expressed in its meta-language, which itself is a superset of Miranda. The LETOS compiler is smaller than comparable tools, yet LETOS is powerful enough to support

  17. Lightweight aluminum shock absorbers; Leichtbau-Stossdaempfer aus Aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Kusche, R. [Serienentwicklung, ThyssenKrupp Bilstein GmbH, Ennepetal (Germany)

    2004-12-01

    One way in which the automotive industry is striving to reduce costs and environmental impact is by continuously lowering the fuel consumption of vehicles. To achieve this objective, lightweight materials are increasingly being used in automotive design. Increasing demands are also being made on shock absorber suppliers to reduce weight. (orig.)

  18. Developments in Emission Measurements Using Lightweight Sensors and Samplers.

    Science.gov (United States)

    Lightweight emission measurement systems making use of miniaturized sensors and samplers have been developed for portable and aerial sampling for an array of pollutants. Shoebox-sized systems called “Kolibri”, weighing 3-5 kg, have been deployed on NASA-flown unmanned...

  19. Performance of Lightweight Natural-Fiber Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Hardjasaputra Harianto

    2017-01-01

    Full Text Available Concrete, the most common construction material, has negligible tension capacity. However, a reinforcement material such as natural fibers, can be used to improve the tensile properties of concrete. This paper presents experiments conducted on Super Lightweight Concrete mixed with coconut fibers (SLNFRC. Coconut fibers are regarded as one of the toughest natural fibers to strengthen concrete. Coconut fiber reinforced composites have been considered as a sustainable construction material because the fibers are derived from waste. These wastes, which are available in large quantities in Asia, have to be extracted from the husk of coconut fruits and must pass a mechanical process before being added to a concrete mixture. The Super Lightweight Concrete was made by mixing concrete paste with foam agent that can reduce the overall weight of concrete up to 60% with compressive strength up to 6 MPa. The Super Lightweight Concrete is intended to be used for non-structural walls, as alternative conventional construction materials such as brick walls. The influence of coconut fibers content in increasing the flexural tensile strength of Super Lightweight Concrete was studied in this research. The fiber content studied include 0%, 0.1%, 0.175%, and 0.25% by weight of cement content. Sixteen specimens of SLNFRC mini beams of 60 mm x 60 mm x 300 mm were tested to failure to investigate their flexural strengths. The optimum percent fibers yielding higher tensile strength was found to be 0.175%

  20. Reuse of thermosetting plastic waste for lightweight concrete.

    Science.gov (United States)

    Panyakapo, Phaiboon; Panyakapo, Mallika

    2008-01-01

    This paper presents the utilization of thermosetting plastic as an admixture in the mix proportion of lightweight concrete. Since this type of plastic cannot be melted in the recycling process, its waste is expected to be more valuable by using as an admixture for the production of non-structural lightweight concrete. Experimental tests for the variation of mix proportion were carried out to determine the suitable proportion to achieve the required properties of lightweight concrete, which are: low dry density and acceptable compressive strength. The mix design in this research is the proportion of plastic, sand, water-cement ratio, aluminum powder, and lignite fly ash. The experimental results show that the plastic not only leads to a low dry density concrete, but also a low strength. It was found that the ratio of cement, sand, fly ash, and plastic equal to 1.0:0.8:0.3:0.9 is an appropriate mix proportion. The results of compressive strength and dry density are 4.14N/mm2 and 1395 kg/m3, respectively. This type of concrete meets most of the requirements for non-load-bearing lightweight concrete according to ASTM C129 Type II standard.

  1. data sets Simulations in articulating light-weight PRS

    NARCIS (Netherlands)

    Van den Berg, Bert

    2008-01-01

    The data sets are output of 3 different steps in the development a simulations of a PRS as described in chapter 3.3: Simulations in articulating light-weight PRS A case for Pedagogy-oriented and Rating-based Hybrid Recommendation Strategies Rob Nadolski, Bert van den Berg, Adriana Berlanga, Hans

  2. Influence of site curing on bond properties of reinforced lightweight ...

    African Journals Online (AJOL)

    ... the requirements for structural lightweight concrete. The developed compressive strength and pull-out strength under both site curing conditions were relatively lower than full water curing condition but still were higher than minimum requirement as per standard. Journal of Civil Engineering Research and Practice Vol.

  3. Reducing CO2 Emissions through Lightweight Design and Manufacturing

    Science.gov (United States)

    Carruth, Mark A.; Allwood, Julian M.; Milford, Rachel L.

    2011-05-01

    To meet targeted 50% reductions in industrial CO2 emissions by 2050, demand for steel and aluminium must be cut. Many steel and aluminium products include redundant material, and the manufacturing routes to produce them use more material than is necessary. Lightweight design and optimized manufacturing processes offer a means of demand reduction, whilst creating products to perform the same service as existing ones. This paper examines two strategies for demand reduction: lightweight product design; and minimizing yield losses through the product supply chain. Possible mass savings are estimated for specific case-studies on metal-intensive products, such as I-beams and food cans. These estimates are then extrapolated to other sectors to produce a global estimate for possible demand reductions. Results show that lightweight product design may offer potential mass savings of up to 30% for some products, whilst yield in the production of others could be improved by over 20%. If these two strategies could be combined for all products, global demand for steel and aluminium would be reduced by nearly 50%. The impact of demand reduction on CO2 emissions is presented, and barriers to the adoption of new, lightweight technologies are discussed.

  4. Robustness of Modal Parameter Estimation Methods Applied to Lightweight Structures

    DEFF Research Database (Denmark)

    Dickow, Kristoffer Ahrens; Kirkegaard, Poul Henning; Andersen, Lars Vabbersgaard

    2013-01-01

    On-going research is concerned with the losses that occur at junctions in lightweight building structures. Recently the authors have investigated the underlying uncertainties related to both measurement, material and craftsmanship of timber junctions by means of repeated modal testing on a number...

  5. Accuracy of Dynamic and Acoustic Analysis of Lightweight Panel Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Dickow, Kristoffer Ahrens; Andersen, Lars Vabbersgaard

    2012-01-01

    in such buildings is important. In the lowfrequency range, prediction of sound and vibration in building structures may be achieved by finite-element analysis (FEA). The aim of this paper is to compare the two commercial codes ABAQUS and ANSYS for FEA of an acoustic-structural coupling in a timber lightweight panel...

  6. Study of the strength characteristics of protein-based lightweight ...

    African Journals Online (AJOL)

    Compressive strength test was carried out on the protein-based lightweight foamed concrete produced with cement partially replaced by rice husk ash to ascertain its strength characteristics. Standard concrete cubes of 150 x 150 x 150 mm were produced using ordinary Portland cement (OPC), fine aggregate, aqueous ...

  7. APE: Authenticated Permutation-Based Encryption for Lightweight Cryptography

    DEFF Research Database (Denmark)

    Andreeva, Elena; Bilgin, Begül; Bogdanov, Andrey

    2015-01-01

    The domain of lightweight cryptography focuses on cryptographic algorithms for extremely constrained devices. It is very costly to avoid nonce reuse in such environments, because this requires either a hardware source of randomness, or non-volatile memory to store a counter. At the same time, a lot...

  8. Metal-bending brake facilitates lightweight, close-tolerance fabrication

    Science.gov (United States)

    Ercoline, A. L.; Wilton, K. B.

    1964-01-01

    A lightweight, metal bending brake ensures very accurate bends. Features of the brake that adapt it for making complex reverse bends to close tolerances are a pronounced relief or cutaway of the underside of the bodyplate combined with modification in the leaf design and its suspension.

  9. STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

    Directory of Open Access Journals (Sweden)

    NOZEMTСEV Alexandr Sergeevich

    2013-02-01

    Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

  10. Lightweighting Impacts on Fuel Economy, Cost, and Component Losses

    Energy Technology Data Exchange (ETDEWEB)

    Brooker, A. D.; Ward, J.; Wang, L.

    2013-01-01

    The Future Automotive Systems Technology Simulator (FASTSim) is the U.S. Department of Energy's high-level vehicle powertrain model developed at the National Renewable Energy Laboratory. It uses a time versus speed drive cycle to estimate the powertrain forces required to meet the cycle. It simulates the major vehicle powertrain components and their losses. It includes a cost model based on component sizing and fuel prices. FASTSim simulated different levels of lightweighting for four different powertrains: a conventional gasoline engine vehicle, a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a battery electric vehicle (EV). Weight reductions impacted the conventional vehicle's efficiency more than the HEV, PHEV and EV. Although lightweighting impacted the advanced vehicles' efficiency less, it reduced component cost and overall costs more. The PHEV and EV are less cost effective than the conventional vehicle and HEV using current battery costs. Assuming the DOE's battery cost target of $100/kWh, however, the PHEV attained similar cost and lightweighting benefits. Generally, lightweighting was cost effective when it costs less than $6/kg of mass eliminated.

  11. FY2013 Lightweight Materials R&D Annual Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2014-02-01

    As part of the U.S. Department of Energy’s (DOE’s) Vehicle Technologies Program (VTO), the Lightweight Materials (LM) activity focuses on the development and validation of advanced materials and manufacturing technologies to significantly reduce light and heavy duty vehicle weight without compromising other attributes such as safety, performance, recyclability, and cost.

  12. Closing the innovation cycle in lightweighting compressor pistons technolog

    NARCIS (Netherlands)

    Wentzel, C.; Eijk, A.; Groenewegen, G.; Bergsma, O.

    2016-01-01

    What started out as an exercise in exploring the weight reduction potential of those allegedly “heavy recip crossheads”, turned out to be a fast leap towards implementation of a new hybrid material concept for very lightweight pistons. This was enabled by a next phase in the EFRC R&D group research

  13. Closing the innovation cycle in lightweighting compressor pistons technology

    NARCIS (Netherlands)

    Wentzel, C.M.; Eijk, A.; Groenewegen, G.; Bergsma, O.K.

    2016-01-01

    What started out as an exercise in exploring the weight reduction potential of those allegedly “heavy recip crossheads”, turned out to be a fast leap towards implementation of a new hybrid material concept for very lightweight pistons. This was enabled by a next phase in the EFRC R&D group

  14. FY2010 Annual Progress Report for Lightweighting Materials

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2011-01-15

    The Lightweight Materials activity (LM) within the Vehicle Technologies Program focuses on the development and validation of advanced materials and manufacturing technologies to significantly reduce light and heavy duty vehicle weight without compromising other attributes such as safety, performance, recyclability, and cost.

  15. Lightweight Inexpensive Ozone Lidar Telescope Using a Plastic Fresnel Lens

    Science.gov (United States)

    DeYoung, Russell J.; Notari, Anthony; Carrion, William; Pliutau, Denis

    2014-01-01

    An inexpensive lightweight ozone lidar telescope was designed, constructed and operated during an ozone lidar field campaign. This report summarizes the design parameters and performance of the plastic Fresnel lens telescope and shows the ozone lidar performance compared to Zemax calculations.

  16. HOKES/POKES : Light-weight resource sharing

    NARCIS (Netherlands)

    Bos, Herbert; Samwel, Bart

    2003-01-01

    In this paper, we explain mechanisms for providing embedded network processors and other low-level programming environments with light-weight support for safe resource sharing. The solution consists of a host part, known as HOKES, and a network processor part, known as POKES. As common operating

  17. Vibrations in a Multi-Storey Lightweight Building Structure

    DEFF Research Database (Denmark)

    Andersen, Lars Vabbersgaard; Kirkegaard, Poul Henning

    2013-01-01

    This paper provides a quantification of the changes in vibration level that can be expected in a lightweight multi-storey wooden building due to reduced connection stiffness or added nonstructural mass. Firstly, the impact of changes in the floor-to-wall connections is examined. Secondly, a study...

  18. Development of lightweight mortars targeted on the high strength, low density and low permeability

    NARCIS (Netherlands)

    Spiesz, P.R.; Yu, Q.; Brouwers, H.J.H.; Uzoegbo, H.C.; Schmidt, W.

    2013-01-01

    This article presents a mix design methodology for the development of cement-based lightweight mortars. Expanded-glass lightweight aggregates were used in this study as the lightweight material. The mix design was developed applying the packing theory using the modified Andreasen and Andersen model

  19. Lightweight panel study 2012: Perceptions and usage by North American wood products manufacturers

    Science.gov (United States)

    Urs Buehlmann; Matt Bumgardner; Karl D. Forth

    2012-01-01

    Lightweight panels (panels made of two thin panels on the outside and a lightweight material in the core) can offer enhanced performance, reduced material use, and new design opportunities over traditional types of panels. Opportunities exist for the adoption of lightweight panels by the secondary wood industry in North America, as 62 percent of respondents to a recent...

  20. Dynamic Aperture Measurements at the Advanced Light Source

    International Nuclear Information System (INIS)

    Decking, W.; Robin, D.

    1999-01-01

    A large dynamic aperture for a storage ring is of importance for long lifetimes and a high injection efficiency. Measurements of the dynamic aperture of the third generation synchrotron light source Advanced Light Source (ALS) using beam excitation with kicker magnets are presented. The experiments were done for various accelerator conditions, allowing us to investigate the influence of different working points, chromaticities, insertion devices, etc.. The results are compared both with tracking calculations and a simple model for the dynamic aperture yielding good agreements. This gives us confidence in the predictability of the nonlinear accelerator model. This is especially important for future ALS upgrades as well as new storage ring designs

  1. Electromagnetic Formation Flight (EMFF) for Sparse Aperture Arrays

    Science.gov (United States)

    Kwon, Daniel W.; Miller, David W.; Sedwick, Raymond J.

    2004-01-01

    Traditional methods of actuating spacecraft in sparse aperture arrays use propellant as a reaction mass. For formation flying systems, propellant becomes a critical consumable which can be quickly exhausted while maintaining relative orientation. Additional problems posed by propellant include optical contamination, plume impingement, thermal emission, and vibration excitation. For these missions where control of relative degrees of freedom is important, we consider using a system of electromagnets, in concert with reaction wheels, to replace the consumables. Electromagnetic Formation Flight sparse apertures, powered by solar energy, are designed differently from traditional propulsion systems, which are based on V. This paper investigates the design of sparse apertures both inside and outside the Earth's gravity field.

  2. MD1405: Demonstration of forced dynamic aperture measurements at injection

    CERN Document Server

    Carlier, Felix Simon; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2017-01-01

    Accurate measurements of dynamic aperture become more important for the LHC as it advances into increasingly nonlinear regimes of operations, as well as for the High Luminosity LHC where machine nonlinearities will have a significantly larger impact. Direct dynamic aperture measurements at top energy in the LHC are challenging, and conventional single kick methods are not viable. Dynamic aperture measurements under forced oscillation of AC dipoles have been proposed as s possible alternative observable. A first demonstration of forced DA measurements at injections energy is presented.

  3. Complementary bowtie aperture for localizing and enhancing optical magnetic field

    Science.gov (United States)

    Zhou, Nan; Kinzel, Edward C.; Xu, Xianfan

    2011-08-01

    Nanoscale bowtie antenna and bowtie aperture antenna have been shown to generate strongly enhanced and localized electric fields below the diffraction limit in the optical frequency range. According to Babinet's principle, their complements will be efficient for concentrating and enhancing magnetic fields. In this Letter, we discuss the enhancement of magnetic field intensity of nanoscale complementary bowtie aperture as well as complementary bowtie aperture antenna, or diabolo nanoantenna. We show that the complementary bowtie antenna resonates at a smaller wavelength and thus is more suitable for applications near visible wavelengths. The near-field magnetic intensity can be further enhanced by the addition of groove structures that scatter surface plasmon.

  4. Precise Alignment and Permanent Mounting of Thin and Lightweight X-ray Segments

    Science.gov (United States)

    Biskach, Michael P.; Chan, Kai-Wing; Hong, Melinda N.; Mazzarella, James R.; McClelland, Ryan S.; Norman, Michael J.; Saha, Timo T.; Zhang, William W.

    2012-01-01

    To provide observations to support current research efforts in high energy astrophysics. future X-ray telescope designs must provide matching or better angular resolution while significantly increasing the total collecting area. In such a design the permanent mounting of thin and lightweight segments is critical to the overall performance of the complete X-ray optic assembly. The thin and lightweight segments used in the assemhly of the modules are desigued to maintain and/or exceed the resolution of existing X-ray telescopes while providing a substantial increase in collecting area. Such thin and delicate X-ray segments are easily distorted and yet must be aligned to the arcsecond level and retain accurate alignment for many years. The Next Generation X-ray Optic (NGXO) group at NASA Goddard Space Flight Center has designed, assembled. and implemented new hardware and procedures mth the short term goal of aligning three pairs of X-ray segments in a technology demonstration module while maintaining 10 arcsec alignment through environmental testing as part of the eventual design and construction of a full sized module capable of housing hundreds of X-ray segments. The recent attempts at multiple segment pair alignment and permanent mounting is described along with an overview of the procedure used. A look into what the next year mll bring for the alignment and permanent segment mounting effort illustrates some of the challenges left to overcome before an attempt to populate a full sized module can begin.

  5. Design of lightweight magnesium car body structure under crash and vibration constraints

    Directory of Open Access Journals (Sweden)

    Morteza Kiani

    2014-06-01

    Full Text Available Car body design in view of structural performance and lightweighting is a challenging task due to all the performance targets that must be satisfied such as vehicle safety and ride quality. In this paper, material replacement along with multidisciplinary design optimization strategy is proposed to develop a lightweight car body structure that satisfies the crash and vibration criteria while minimizing weight. Through finite element simulations, full frontal, offset frontal, and side crashes of a full car model are evaluated for peak acceleration, intrusion distance, and the internal energy absorbed by the structural parts. In addition, the first three fundamental natural frequencies are combined with the crash metrics to form the design constraints. The wall thicknesses of twenty-two parts are considered as the design variables. Latin Hypercube Sampling is used to sample the design space, while Radial Basis Function methodology is used to develop surrogate models for the selected crash responses at multiple sites as well as the first three fundamental natural frequencies. A nonlinear surrogate-based optimization problem is formulated for mass minimization under crash and vibration constraints. Using Sequential Quadratic Programming, the design optimization problem is solved with the results verified by finite element simulations. The performance of the optimum design with magnesium parts shows significant weight reduction and better performance compared to the baseline design.

  6. Lightweight Sensor Authentication Scheme for Energy Efficiency in Ubiquitous Computing Environments.

    Science.gov (United States)

    Lee, Jaeseung; Sung, Yunsick; Park, Jong Hyuk

    2016-12-01

    The Internet of Things (IoT) is the intelligent technologies and services that mutually communicate information between humans and devices or between Internet-based devices. In IoT environments, various device information is collected from the user for intelligent technologies and services that control the devices. Recently, wireless sensor networks based on IoT environments are being used in sectors as diverse as medicine, the military, and commerce. Specifically, sensor techniques that collect relevant area data via mini-sensors after distributing smart dust in inaccessible areas like forests or military zones have been embraced as the future of information technology. IoT environments that utilize smart dust are composed of the sensor nodes that detect data using wireless sensors and transmit the detected data to middle nodes. Currently, since the sensors used in these environments are composed of mini-hardware, they have limited memory, processing power, and energy, and a variety of research that aims to make the best use of these limited resources is progressing. This paper proposes a method to utilize these resources while considering energy efficiency, and suggests lightweight mutual verification and key exchange methods based on a hash function that has no restrictions on operation quantity, velocity, and storage space. This study verifies the security and energy efficiency of this method through security analysis and function evaluation, comparing with existing approaches. The proposed method has great value in its applicability as a lightweight security technology for IoT environments.

  7. The LASS [Larger Aperture Superconducting Solenoid] spectrometer

    International Nuclear Information System (INIS)

    Aston, D.; Awaji, N.; Barnett, B.

    1986-04-01

    LASS is the acronym for the Large Aperture Superconducting Solenoid spectrometer which is located in an rf-separated hadron beam at the Stanford Linear Accelerator Center. This spectrometer was constructed in order to perform high statistics studies of multiparticle final states produced in hadron reactions. Such reactions are frequently characterized by events having complicated topologies and/or relatively high particle multiplicity. Their detailed study requires a spectrometer which can provide good resolution in momentum and position over almost the entire solid angle subtended by the production point. In addition, good final state particle identification must be available so that separation of the many kinematically-overlapping final states can be achieved. Precise analyses of the individual reaction channels require high statistics, so that the spectrometer must be capable of high data-taking rates in order that such samples can be acquired in a reasonable running time. Finally, the spectrometer must be complemented by a sophisticated off-line analysis package which efficiently finds tracks, recognizes and fits event topologies and correctly associates the available particle identification information. This, together with complicated programs which perform specific analysis tasks such as partial wave analysis, requires a great deal of software effort allied to a very large computing capacity. This paper describes the construction and performance of the LASS spectrometer, which is an attempt to realize the features just discussed. The configuration of the spectrometer corresponds to the data-taking on K + and K - interactions in hydrogen at 11 GeV/c which took place in 1981 and 1982. This constitutes a major upgrade of the configuration used to acquire lower statistics data on 11 GeV/c K - p interactions during 1977 and 1978, which is also described briefly

  8. RADARSAT-1 synthetic aperture radar analysis

    Energy Technology Data Exchange (ETDEWEB)

    Simecek-Beatty, D. [National Oceanic and Atmospheric Adminstration, National Ocean Service, Seattle, WA (United States). Office of Response and Restoration; Pichel, W.G. [National Oceanic and Atmospheric Administration, National Environmental Satellite, Data and Information Service, Camp Springs, MD (United States). Office of Research and Applications

    2006-07-01

    The M/V Selendang Ayu grounded off Unalaska Island in Alaska on December 8, 2004, and spilled over 1270 m{sup 3} of oil and an unknown quantity of soybeans. The freighter grounded nearshore in a high-wave energy zone along a remote and rugged coastline, a terrain which can cause difficulties for remote sensors in detecting oil slicks. In addition, guano, kelp beds, whale and fish sperm, and releases from fishing activities generated biogenic films on the sea surface that had a signature similar to that of petroleum films. RADARSAT-1 synthetic aperture radar (SAR) imagery was used as part of the response effort to assist in the pollution monitoring effort. This paper described the methodology and results of the RADARSAT-1 analysis. Detailed information on the spill response was reported daily, and provided an opportunity to compare field observations with RADARSAT-1 SAR imagery. Observers recorded observations onto electronic maps during 35 aerial surveillance flights. Fifty-seven incident reports describing the vessel status were also used for comparison. Using screening criteria for the favorable wind and wave conditions, 37 images were available for viewing the wreck, and 22 images were acceptable for oil slick viewing. Image analysis for the wreck suggested that the sensor has the resolution and capability to monitor a grounded freighter. Visual inspection of the images showed that SAR can capture changes in vessel status, such as the gradual sinking of the bow. However, SAR's oil slick detection capability was disappointing due to the significant number of biogenic films in the nearshore areas of Alaska. It was concluded that future work should concentrate on developing a ranking system to indicate analysis confidence that a particular image does in fact contain a petroleum pocket. 25 refs., 2 tabs., 10 figs.

  9. The LASS (Larger Aperture Superconducting Solenoid) spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Aston, D.; Awaji, N.; Barnett, B.; Bienz, T.; Bierce, R.; Bird, F.; Bird, L.; Blockus, D.; Carnegie, R.K.; Chien, C.Y.

    1986-04-01

    LASS is the acronym for the Large Aperture Superconducting Solenoid spectrometer which is located in an rf-separated hadron beam at the Stanford Linear Accelerator Center. This spectrometer was constructed in order to perform high statistics studies of multiparticle final states produced in hadron reactions. Such reactions are frequently characterized by events having complicated topologies and/or relatively high particle multiplicity. Their detailed study requires a spectrometer which can provide good resolution in momentum and position over almost the entire solid angle subtended by the production point. In addition, good final state particle identification must be available so that separation of the many kinematically-overlapping final states can be achieved. Precise analyses of the individual reaction channels require high statistics, so that the spectrometer must be capable of high data-taking rates in order that such samples can be acquired in a reasonable running time. Finally, the spectrometer must be complemented by a sophisticated off-line analysis package which efficiently finds tracks, recognizes and fits event topologies and correctly associates the available particle identification information. This, together with complicated programs which perform specific analysis tasks such as partial wave analysis, requires a great deal of software effort allied to a very large computing capacity. This paper describes the construction and performance of the LASS spectrometer, which is an attempt to realize the features just discussed. The configuration of the spectrometer corresponds to the data-taking on K and K interactions in hydrogen at 11 GeV/c which took place in 1981 and 1982. This constitutes a major upgrade of the configuration used to acquire lower statistics data on 11 GeV/c K p interactions during 1977 and 1978, which is also described briefly.

  10. Mathematical Problems in Synthetic Aperture Radar

    Science.gov (United States)

    Klein, Jens

    2010-10-01

    This thesis is concerned with problems related to Synthetic Aperture Radar (SAR). The thesis is structured as follows: The first chapter explains what SAR is, and the physical and mathematical background is illuminated. The following chapter points out a problem with a divergent integral in a common approach and proposes an improvement. Numerical comparisons are shown that indicate that the improvements allow for a superior image quality. Thereafter the problem of limited data is analyzed. In a realistic SAR-measurement the data gathered from the electromagnetic waves reflected from the surface can only be collected from a limited area. However the reconstruction formula requires data from an infinite distance. The chapter gives an analysis of the artifacts which can obscure the reconstructed images due to this problem. Additionally, some numerical examples are shown that point to the severity of the problem. In chapter 4 the fact that data is available only from a limited area is used to propose a new inversion formula. This inversion formula has the potential to make it easier to suppress artifacts due to limited data and, depending on the application, can be refined to a fast reconstruction formula. In the penultimate chapter a solution to the problem of left-right ambiguity is presented. This problem exists since the invention of SAR and is caused by the geometry of the measurements. This leads to the fact that only symmetric images can be obtained. With the solution from this chapter it is possible to reconstruct not only the even part of the reflectivity function, but also the odd part, thus making it possible to reconstruct asymmetric images. Numerical simulations are shown to demonstrate that this solution is not affected by stability problems as other approaches have been. The final chapter develops some continuative ideas that could be pursued in the future.

  11. Autofocus algorithm for synthetic aperture radar imaging with large curvilinear apertures

    Science.gov (United States)

    Bleszynski, E.; Bleszynski, M.; Jaroszewicz, T.

    2013-05-01

    An approach to autofocusing for large curved synthetic aperture radar (SAR) apertures is presented. Its essential feature is that phase corrections are being extracted not directly from SAR images, but rather from reconstructed SAR phase-history data representing windowed patches of the scene, of sizes sufficiently small to allow the linearization of the forward- and back-projection formulae. The algorithm processes data associated with each patch independently and in two steps. The first step employs a phase-gradient-type method in which phase correction compensating (possibly rapid) trajectory perturbations are estimated from the reconstructed phase history for the dominant scattering point on the patch. The second step uses phase-gradient-corrected data and extracts the absolute phase value, removing in this way phase ambiguities and reducing possible imperfections of the first stage, and providing the distances between the sensor and the scattering point with accuracy comparable to the wavelength. The features of the proposed autofocusing method are illustrated in its applications to intentionally corrupted small-scene 2006 Gotcha data. The examples include the extraction of absolute phases (ranges) for selected prominent point targets. They are then used to focus the scene and determine relative target-target distances.

  12. Strain hardening by dynamic slip band refinement in a high-Mn lightweight steel

    International Nuclear Information System (INIS)

    Welsch, E.; Ponge, D.; Hafez Haghighat, S.M.; Sandlöbes, S.; Choi, P.; Herbig, M.; Zaefferer, S.; Raabe, D.

    2016-01-01

    The strain hardening mechanism of a high-Mn lightweight steel (Fe-30.4Mn-8Al-1.2C (wt%)) is investigated by electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM). The alloy is characterized by a constant high strain hardening rate accompanied by high strength and high ductility (ultimate tensile strength: 900 MPa, elongation to fracture: 68%). Deformation microstructures at different strain levels are studied in order to reveal and quantify the governing structural parameters at micro- and nanometer scales. As the material deforms mainly by planar dislocation slip causing the formation of slip bands, we quantitatively study the evolution of the slip band spacing during straining. The flow stress is calculated from the slip band spacing on the basis of the passing stress. The good agreement between the calculated values and the tensile test data shows dynamic slip band refinement as the main strain hardening mechanism, enabling the excellent mechanical properties. This novel strain hardening mechanism is based on the passing stress acting between co-planar slip bands in contrast to earlier attempts to explain the strain hardening in high-Mn lightweight steels that are based on grain subdivision by microbands. We discuss in detail the formation of the finely distributed slip bands and the gradual reduction of the spacing between them, leading to constantly high strain hardening. TEM investigations of the precipitation state in the as-quenched state show finely dispersed atomically ordered clusters (size < 2 nm). The influence of these zones on planar slip is discussed.

  13. Highly uniform parallel microfabrication using a large numerical aperture system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zi-Yu; Su, Ya-Hui, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [School of Electrical Engineering and Automation, Anhui University, Hefei 230601 (China); Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Chu, Jia-Ru; Wu, Dong, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)

    2016-07-11

    In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

  14. Thermal front propagation in variable aperture fracture–matrix system

    Indian Academy of Sciences (India)

    Abstract. A numerical study on the effect of complex fracture aperture geometry .... have revealed that natural porous media exhibit self-similarity up to a certain scale (Feder 1988) ...... Handbook of terrestrial heat-flow density determination.

  15. The development of deep learning in synthetic aperture radar imagery

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2017-05-01

    Full Text Available sensing techniques but comes at the price of additional complexities. To adequately cope with these, researchers have begun to employ advanced machine learning techniques known as deep learning to Synthetic Aperture Radar data. Deep learning represents...

  16. Ambiguity Of Doppler Centroid In Synthetic-Aperture Radar

    Science.gov (United States)

    Chang, Chi-Yung; Curlander, John C.

    1991-01-01

    Paper discusses performances of two algorithms for resolution of ambiguity in estimated Doppler centroid frequency of echoes in synthetic-aperture radar. One based on range-cross-correlation technique, other based on multiple-pulse-repetition-frequency technique.

  17. Stellwagen Bank National Marine Sanctuary - Synthetic Aperture Radar (SAR) Imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geodatabase contains Synthetic Aperture Radar images (SAR), which consist of a fine resolution (12.5-50m), two-dimensional radar backscatter map of the...

  18. Design of a space-based infrared imaging interferometer

    Science.gov (United States)

    Hart, Michael; Hope, Douglas; Romeo, Robert

    2017-07-01

    Present space-based optical imaging sensors are expensive. Launch costs are dictated by weight and size, and system design must take into account the low fault tolerance of a system that cannot be readily accessed once deployed. We describe the design and first prototype of the space-based infrared imaging interferometer (SIRII) that aims to mitigate several aspects of the cost challenge. SIRII is a six-element Fizeau interferometer intended to operate in the short-wave and midwave IR spectral regions over a 6×6 mrad field of view. The volume is smaller by a factor of three than a filled-aperture telescope with equivalent resolving power. The structure and primary optics are fabricated from light-weight space-qualified carbon fiber reinforced polymer; they are easy to replicate and inexpensive. The design is intended to permit one-time alignment during assembly, with no need for further adjustment once on orbit. A three-element prototype of the SIRII imager has been constructed with a unit telescope primary mirror diameter of 165 mm and edge-to-edge baseline of 540 mm. The optics, structure, and interferometric signal processing principles draw on experience developed in ground-based astronomical applications designed to yield the highest sensitivity and resolution with cost-effective optical solutions. The initial motivation for the development of SIRII was the long-term collection of technical intelligence from geosynchronous orbit, but the scalable nature of the design will likely make it suitable for a range of IR imaging scenarios.

  19. Scaling Laws for Dynamic Aperture due to Chromatic Sextupoles

    CERN Document Server

    Scandale, Walter

    1997-01-01

    Scaling laws for the dynamic aperture due to chromatic sextupoles are investigated. The problem is addressed in a simplified lattice model containing 4 N identical cells and one linear betatron phase shifter to break the overall cell-lattice symmetry. Two families of chromatic sextupoles are used to compensate the natural chromaticity. Analytical formulae for the dynamic apertur as a function of the number of cells and of the cell length are found and confirmed through computer tracking.

  20. Transmission of high-power electron beams through small apertures

    International Nuclear Information System (INIS)

    Tschalär, C.; Alarcon, R.; Balascuta, S.; Benson, S.V.; Bertozzi, W.; Boyce, J.R.; Cowan, R.; Douglas, D.; Evtushenko, P.; Fisher, P.; Ihloff, E.; Kalantarians, N.; Kelleher, A.; Legg, R.; Milner, R.G.; Neil, G.R.; Ou, L.; Schmookler, B.; Tennant, C.; Williams, G.P.

    2013-01-01

    Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 h continuous run

  1. Phase Centers of Subapertures in a Tapered Aperture Array.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  2. Apodised aperture using rotation of plane of polarization

    International Nuclear Information System (INIS)

    Simmons, W.W.; Leppelmeier, G.W.; Johnson, B.C.

    1975-01-01

    An apodised aperture based on the rotation of plane of polarization producing desirable characteristics on a transmitted light beam such as beam profiling in high flux laser amplifier chains is described. The apodised aperture is made with a lossless element by using one or more polarizers and/or analyzers and magneto-optical Faraday means for selectively rotating the plane of polarized radiation over the cross section to effect the desired apodisation

  3. Miniature Sensor Probe for O2, CO2, and H2O Monitoring in Space Suits, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced space suits require lightweight, low-power, durable sensors for monitoring critical life support materials. No current compact sensors have the tolerance...

  4. Space space space

    CERN Document Server

    Trembach, Vera

    2014-01-01

    Space is an introduction to the mysteries of the Universe. Included are Task Cards for independent learning, Journal Word Cards for creative writing, and Hands-On Activities for reinforcing skills in Math and Language Arts. Space is a perfect introduction to further research of the Solar System.

  5. Transport of Particle Swarms Through Variable Aperture Fractures

    Science.gov (United States)

    Boomsma, E.; Pyrak-Nolte, L. J.

    2012-12-01

    Particle transport through fractured rock is a key concern with the increased use of micro- and nano-size particles in consumer products as well as from other activities in the sub- and near surface (e.g. mining, industrial waste, hydraulic fracturing, etc.). While particle transport is often studied as the transport of emulsions or dispersions, particles may also enter the subsurface from leaks or seepage that lead to particle swarms. Swarms are drop-like collections of millions of colloidal-sized particles that exhibit a number of unique characteristics when compared to dispersions and emulsions. Any contaminant or engineered particle that forms a swarm can be transported farther, faster, and more cohesively in fractures than would be expected from a traditional dispersion model. In this study, the effects of several variable aperture fractures on colloidal swarm cohesiveness and evolution were studied as a swarm fell under gravity and interacted with the fracture walls. Transparent acrylic was used to fabricate synthetic fracture samples with (1) a uniform aperture, (2) a converging region followed by a uniform region (funnel shaped), (3) a uniform region followed by a diverging region (inverted funnel), and (4) a cast of a an induced fracture from a carbonate rock. All of the samples consisted of two blocks that measured 100 x 100 x 50 mm. The minimum separation between these blocks determined the nominal aperture (0.5 mm to 20 mm). During experiments a fracture was fully submerged in water and swarms were released into it. The swarms consisted of a dilute suspension of 3 micron polystyrene fluorescent beads (1% by mass) with an initial volume of 5μL. The swarms were illuminated with a green (525 nm) LED array and imaged optically with a CCD camera. The variation in fracture aperture controlled swarm behavior. Diverging apertures caused a sudden loss of confinement that resulted in a rapid change in the swarm's shape as well as a sharp increase in its velocity

  6. Oil Slick Characterization Using Synthetic Aperture Radar

    Science.gov (United States)

    Jones, C. E.; Breivik, O.; Brekke, C.; Skrunes, S.; Holt, B.

    2015-12-01

    Oil spills are a hazard worldwide with potential of causing high impact disasters, and require an active oil spill response capability to protect personnel, the ecosystem, and the energy supply. As the amount of oil in traditionally accessible reserves decline, there will be increasing oil extraction from the Arctic and deep-water wells, both new sources with high risk and high cost for monitoring and response. Although radar has long been used for mapping the spatial extent of oil slicks, it is only since the Deepwater Horizon spill that synthetic aperture radar (SAR) has been shown capable of characterizing oil properties within a slick, and therefore useful for directing response to the recoverable thicker slicks or emulsions. Here we discuss a 2015 Norwegian oil-on-water spill experiment in which emulsions of known quantity and water-to-oil ratio along with a look-alike slick of plant oil were released in the North Sea and imaged with polarimetric SAR (PolSAR) by NASA's UAVSAR instrument for several hours following release. During the experiment, extensive in situ measurements were made from ship or aircraft with meteorological instruments, released drift buoys, and optical/IR imagers. The experiment was designed to provide validation data for development of a physical model relating polarization-dependent electromagnetic scattering to the dielectric properties of oil mixed with ocean water, which is the basis for oil characterization with SAR. Data were acquired with X-, C-, and L-band satellite-based SARs to enable multi-frequency comparison of characterization capabilities. In addition, the data are used to develop methods to differentiate mineral slicks from biogenic look-alikes, and to better understand slick weathering and dispersion. The results will provide a basis for modeling oil-in-ice spills, currently a high priority for nations involved in Arctic oil exploration. Here we discuss the Norwegian experiment, the validation data, and the results of

  7. Wind energy applications of synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Bruun Christiansen, M.

    2006-11-15

    Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting wind fields are valuable in offshore wind energy planning as a supplement to on site measurements, which are costly and sparse, and model wind fields, which are not fully validated. Two applications of SAR measurements in offshore wind energy planning are addressed here: the study of wind farm wake effects and the potential of using SAR winds in offshore wind resource assessment. Firstly, wind wakes behind two large offshore wind farms in Denmark Horns Rev and Nysted are identified. A region of reduced wind speed is found downstream of both wind farms from the SAR wind fields. The wake extent and magnitude depends on the wind speed, the atmospheric stability, and the fraction of turbines operating. Wind farm wake effects are detected up to 20 km downwind of the last turbine. This distance is longer than predicted by state-of-the art wake models. Wake losses are typically 10-20% near the wind farms. Secondly, the potential of using SAR wind maps in offshore wind resource assessment is investigated. The resource assessment is made through Weibull fitting to frequency observations of wind speed and requires at least 100 satellite observations per year for a given site of interest. Predictions of the energy density are very sensitive to the wind speed and the highest possible accuracy on SAR wind retrievals is therefore sought. A 1.1 m s{sup -1} deviation on the mean wind speed is found through comparison with mast measurements at Horns Rev. The accuracy on mean wind speeds and energy densities found from satellite measurements varies with different empirical model functions. Additional uncertainties are introduced by the infrequent satellite sampling at fixed times of the day. The accuracy on satellite based wind resource

  8. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, M; Li, R; Xing, L [Stanford UniversitySchool of Medicine, Stanford, CA (United States); Ye, Y [Stanford Univ, Management Science and Engineering, Stanford, Ca (United States); Boyd, S [Stanford University, Electrical Engineering, Stanford, CA (United States)

    2014-06-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  9. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    International Nuclear Information System (INIS)

    Zarepisheh, M; Li, R; Xing, L; Ye, Y; Boyd, S

    2014-01-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  10. A parametric study of rate of advance and area coverage rate performance of synthetic aperture radar.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Hensley, Jr., William H. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Burns, Bryan L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Doerry, Armin Walter [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2014-11-01

    The linear ground distance per unit time and ground area covered per unit time of producing synthetic aperture radar (SAR) imagery, termed rate of advance (ROA) and area coverage rate (ACR), are important metrics for platform and radar performance in surveillance applications. These metrics depend on many parameters of a SAR system such as wavelength, aircraft velocity, resolution, antenna beamwidth, imaging mode, and geometry. Often the effects of these parameters on rate of advance and area coverage rate are non-linear. This report addresses the impact of different parameter spaces as they relate to rate of advance and area coverage rate performance.

  11. The UltraLightweight Technology for Research in Astronomy (ULTRA) Project

    Science.gov (United States)

    Twarog, B. A.; Anthony-Twarog, B. J.; Shawl, S. J.; Hale, R.; Taghavi, R.; Fesen, R.; Etzel, P. B.; Martin, R.; Romeo, R.

    2004-12-01

    The collaborative focus of four academic departments (Univ. of Kansas Aerospace Engineering, Univ. of Kansas Physics & Astronomy, San Diego State University Astronomy and Dartmouth College Astronomy) and a private industry partner (Composite Mirror Applications, Inc.-CMA, Inc.) is a three-year plan to develop and test UltraLightweight Technology for Research in Astronomy (ULTRA). The ULTRA technology, using graphite fiber composites to fabricate mirrors and telescope structures, offers a versatile and cost-effective tool for optical astronomy, including the economical fabrication and operation of telescopes ranging from small (1m or smaller) aperture for education and research to extremely large (30m+) segmented telescopes (ELTs). The specific goal of this NSF-funded three-year Major Research Instrumentation project is to design, build, and test a 1m-class optical tube assembly (OTA) and mirrors constructed entirely from composites. In the first year of the project, the team has built and is field-testing two 0.4m prototypes to validate the optical surfaces and figures of the mirrors and to test and refine the structural dynamics of the OTA. Preparation for design and construction of the 1m telescope is underway. When completed in late 2005, the ULTRA telescope will be operated remotely from Mt. Laguna Observatory east of San Diego, where it will undergo a period of intensive optical and imaging tests. A 0.4m prototype OTA with mirrors (12 kg total weight) will be on display at the meeting. Support of this work by NSF through grants AST-0320784 and AST-0321247, NASA grant NCC5-600, the University of Kansas, and San Diego State University is gratefully acknowledged.

  12. The Hydrological Performance of Lightweight Green Roofs Made From Recycled Waste Materials As the Drainage Layer

    Directory of Open Access Journals (Sweden)

    Afizah Asman Nurul Shahadahtul

    2017-01-01

    Full Text Available Green roofs can be used for promoting infiltration and provide temporary storage spaces. Hence, in urban stormwater structural design, the investigation of the hydrological performance investigation is often required. Thus, this paper presents the results of a hydrological investigation in term of peak flow reduction and green roof’s weight using 0, 2, and 6% slope for three specimens drainage layer in green roofs. Three types of recycled waste are selected for each test bed which is rubber crumbs, palm oil shell, and polyfoam. Another test bed without a drainage layer as a control. The result indicates that rubber crumbs can be used as a stormwater control and runoff reduction while ensuring a good drainage and aeration of the substrate and roofs. From the results obtained shows that rubber crumbs are suitable as a drainage layer and a proposed slope of 6% are suitable for lightweight green roofs.

  13. Experimental Evaluation of Lightweight AAC Masonry Wall Prisms with Ferrocement Layers in Compression and Flexure

    KAUST Repository

    Abdel Mooty, Mohamed; Hendam, Ahmed; Fahmy, Ezzat; Abou Zeid, Mohamed; Haroun, Medhat

    2012-01-01

    An experimental program is designed to evaluate the performance of lightweight autoclaved aerated concrete masonry wall strengthened using ferrocement layers, in a sandwich structure, under in-plane compression and out-of-plane bending. The 25 mm thick ferrocement mortar is reinforced with steel welded wire mesh of 1 mm diameters at 15 mm spacing. Different types of shear connectors are used to evaluate their effect on failure loads. The effect of different design parameters on the wall strength are considered including wall thickness, mortar strength, and type and distribution of shear connectors. A total of 20 prisms are tested in compression and 5 prisms are tested under bending. The proposed ferrocement strengthening technique is easy to apply on existing wall system and results in significant strength and stiffness enhancement of the tested wall specimens. © (2012) Trans Tech Publications.

  14. Advancements of the Lightweight Integrated Solar Array and Transceiver (LISA-T) Small Spacecraft System

    Science.gov (United States)

    Lockett, Tiffany Russell; Martinez, Armando; Boyd, Darren; SanSouice, Michael; Farmer, Brandon; Schneider, Todd; Laue, Greg; Fabisinski, Leo; Johnson, Les; Carr, John A.

    2015-01-01

    This paper describes recent advancements of the Lightweight Integrated Solar Array and Transceiver (LISA-T) currently being developed at NASA's Marshall Space Flight Center. The LISA-T array comprises a launch stowed, orbit deployed structure on which thin-film photovoltaic (PV) and antenna devices are embedded. The system provides significant electrical power generation at low weights, high stowage efficiency, and without the need for solar tracking. Leveraging high-volume terrestrial-market PVs also gives the potential for lower array costs. LISA-T is addressing the power starvation epidemic currently seen by many small-scale satellites while also enabling the application of deployable antenna arrays. Herein, an overview of the system and its applications are presented alongside sub-system development progress and environmental testing plans.

  15. Experimental Evaluation of Lightweight AAC Masonry Wall Prisms with Ferrocement Layers in Compression and Flexure

    KAUST Repository

    Abdel Mooty, Mohamed

    2012-05-01

    An experimental program is designed to evaluate the performance of lightweight autoclaved aerated concrete masonry wall strengthened using ferrocement layers, in a sandwich structure, under in-plane compression and out-of-plane bending. The 25 mm thick ferrocement mortar is reinforced with steel welded wire mesh of 1 mm diameters at 15 mm spacing. Different types of shear connectors are used to evaluate their effect on failure loads. The effect of different design parameters on the wall strength are considered including wall thickness, mortar strength, and type and distribution of shear connectors. A total of 20 prisms are tested in compression and 5 prisms are tested under bending. The proposed ferrocement strengthening technique is easy to apply on existing wall system and results in significant strength and stiffness enhancement of the tested wall specimens. © (2012) Trans Tech Publications.

  16. Weld nugget formation in resistance spot welding of new lightweight sandwich material

    DEFF Research Database (Denmark)

    Sagüés Tanco, J.; Nielsen, Chris Valentin; Chergui, Azeddine

    2015-01-01

    Weldability of a new lightweight sandwich material, LITECOR®, by resistance spot welding is analyzed by experiments and numerical simulations. The spot welding process is accommodated by a first pulse squeezing out the non-conductive polymer core of the sandwich material locally to allow metal......–metal contact. This is facilitated by the use of a shunt tool and is followed by a second pulse for the actual spot welding and nugget formation. A weldability lobe in the time-current space of the second pulse reveals a process window of acceptable size for automotive assembly lines. Weld growth curves...... with experimental results in the range of welding parameters leading to acceptable weld nugget sizes. The validated accuracy of the commercially available software proves the tool useful for assisting the choice of welding parameters....

  17. Linked Metadata - lightweight semantics for data integration (Invited)

    Science.gov (United States)

    Hendler, J. A.

    2013-12-01

    The "Linked Open Data" cloud (http://linkeddata.org) is currently used to show how the linking of datasets, supported by SPARQL endpoints, is creating a growing set of linked data assets. This linked data space has been growing rapidly, and the last version collected is estimated to have had over 35 billion 'triples.' As impressive as this may sound, there is an inherent flaw in the way the linked data story is conceived. The idea is that all of the data is represented in a linked format (generally RDF) and applications will essentially query this cloud and provide mashup capabilities between the various kinds of data that are found. The view of linking in the cloud is fairly simple -links are provided by either shared URIs or by URIs that are asserted to be owl:sameAs. This view of the linking, which primarily focuses on shared objects and subjects in RDF's subject-predicate-object representation, misses a critical aspect of Semantic Web technology. Given triples such as * A:person1 foaf:knows A:person2 * B:person3 foaf:knows B:person4 * C:person5 foaf:name 'John Doe' this view would not consider them linked (barring other assertions) even though they share a common vocabulary. In fact, we get significant clues that there are commonalities in these data items from the shared namespaces and predicates, even if the traditional 'graph' view of RDF doesn't appear to join on these. Thus, it is the linking of the data descriptions, whether as metadata or other vocabularies, that provides the linking in these cases. This observation is crucial to scientific data integration where the size of the datasets, or even the individual relationships within them, can be quite large. (Note that this is not restricted to scientific data - search engines, social networks, and massive multiuser games also create huge amounts of data.) To convert all the triples into RDF and provide individual links is often unnecessary, and is both time and space intensive. Those looking to do on the

  18. Adaptive Backstepping Control of Lightweight Tower Wind Turbine

    DEFF Research Database (Denmark)

    Galeazzi, Roberto; Borup, Kasper Trolle; Niemann, Hans Henrik

    2015-01-01

    the angular deflection of the tower with respect to the vertical axis in response to variations in wind speed. The controller is shown to guarantee asymptotic tracking of the reference trajectory. The performance of the control system is evaluated through deterministic and stochastic simulations including......This paper investigates the feasibility of operating a wind turbine with lightweight tower in the full load region exploiting an adaptive nonlinear controller that allows the turbine to dynamically lean against the wind while maintaining nominal power output. The use of lightweight structures...... for towers and foundations would greatly reduce the construction cost of the wind turbine, however extra features ought be included in the control system architecture to avoid tower collapse. An adaptive backstepping collective pitch controller is proposed for tower point tracking control, i.e. to modify...

  19. Hot stamping advanced manufacturing technology of lightweight car body

    CERN Document Server

    Hu, Ping; He, Bin

    2017-01-01

    This book summarizes the advanced manufacturing technology of original innovations in hot stamping of lightweight car body. A detailed description of the technical system and basic knowledge of sheet metal forming is given, which helps readers quickly understand the relevant knowledge in the field. Emphasis has been placed on the independently developed hot stamping process and equipment, which help describe the theoretical and experimental research on key problems involving stress field, thermal field and phase transformation field in hot stamping process. Also, a description of the formability at elevated temperature and the numerical simulation algorithms for high strength steel hot stamping is given in combination with the experiments. Finally, the book presents some application cases of hot stamping technology such as the lightweight car body design using hot stamping components and gradient hardness components, and the cooling design of the stamping tool. This book is intended for researchers, engineers...

  20. Experimental Validation of a Dynamic Model for Lightweight Robots

    Directory of Open Access Journals (Sweden)

    Alessandro Gasparetto

    2013-03-01

    Full Text Available Nowadays, one of the main topics in robotics research is dynamic performance improvement by means of a lightening of the overall system structure. The effective motion and control of these lightweight robotic systems occurs with the use of suitable motion planning and control process. In order to do so, model-based approaches can be adopted by exploiting accurate dynamic models that take into account the inertial and elastic terms that are usually neglected in a heavy rigid link configuration. In this paper, an effective method for modelling spatial lightweight industrial robots based on an Equivalent Rigid Link System approach is considered from an experimental validation perspective. A dynamic simulator implementing the formulation is used and an experimental test-bench is set-up. Experimental tests are carried out with a benchmark L-shape mechanism.

  1. MODULTEC - Modular technology for lightweight vehicles; MODULTEC - Modultechnologie fuer Leichtmobile

    Energy Technology Data Exchange (ETDEWEB)

    Horlacher, M.; Efler, T.; Wegmann, S.

    2003-07-01

    This final report for the Swiss Federal Office of Energy presents the results of two research projects (MODULTEC I and II) that were carried out between 1995 and 2002. The project's aims were to develop and assess components for light-weight car bodies, study and test novel reinforced plastic materials and to examine the industrial implementation of light-weight vehicles. The report presents details on prototype vehicles and transport systems, as well as crash tests. The development of compound plastics and appropriate adhesives is discussed as is the co-operation with various industrial partners. Various prototype components are described and other associated topics such as recycling, storage of alternative fuels and pedestrian protection issues are discussed.

  2. Performance of Lightweight Natural-Fiber Reinforced Concrete

    OpenAIRE

    Hardjasaputra Harianto; Ng Gino; Urgessa Girum; Lesmana Gabriella; Sidharta Steven

    2017-01-01

    Concrete, the most common construction material, has negligible tension capacity. However, a reinforcement material such as natural fibers, can be used to improve the tensile properties of concrete. This paper presents experiments conducted on Super Lightweight Concrete mixed with coconut fibers (SLNFRC). Coconut fibers are regarded as one of the toughest natural fibers to strengthen concrete. Coconut fiber reinforced composites have been considered as a sustainable construction material beca...

  3. 3D-printing of lightweight cellular composites.

    Science.gov (United States)

    Compton, Brett G; Lewis, Jennifer A

    2014-09-10

    A new epoxy-based ink is reported, which enables 3D printing of lightweight cellular composites with controlled alignment of multiscale, high-aspectratio fiber reinforcement to create hierarchical structures inspired by balsa wood. Young's modulus values up to 10 times higher than existing commercially available 3D-printed polymers are attainable, while comparable strength values are maintained. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Lightweight, high-opacity Bible paper by fiber loading

    Science.gov (United States)

    Klaus Doelle; Oliver Heise; John H. Klungness; Said M. AbuBakr

    2000-01-01

    This paper has been prepared in order to discuss Fiber Loading™ for lightweight, high-opacity bible paper. Incorporating fillers within pulp fibers has been subject to research since 1960 (Green et al. 1962, Scallan et al. 1985, Allen et al. 1992). Fiber Loading™ is a method for manufacturing precipitated calcium carbonate (PCC) directly within the pulp processing...

  5. Lightweight, Durable Army Antennas Using Carbon Nanotube Technology

    Science.gov (United States)

    2013-01-01

    may be adjusted by collecting the sheet on a revolving substrate conveyor belt (e.g., Teflon belt ), as shown in figure 15 (12). SEM images of the... designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an official endorsement or approval of the use...CNT) materials to produce lightweight, flexible, and durable alternatives to existing and future Army antenna designs is explored through fabrication

  6. Tailored Buckling Microlattices as Reusable Light-Weight Shock Absorbers.

    Science.gov (United States)

    Frenzel, Tobias; Findeisen, Claudio; Kadic, Muamer; Gumbsch, Peter; Wegener, Martin

    2016-07-01

    Structures and materials absorbing mechanical (shock) energy commonly exploit either viscoelasticity or destructive modifications. Based on a class of uniaxial light-weight geometrically nonlinear mechanical microlattices and using buckling of inner elements, either a sequence of snap-ins followed by irreversible hysteretic - yet repeatable - self-recovery or multistability is achieved, enabling programmable behavior. Proof-of-principle experiments on three-dimensional polymer microstructures are presented. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Design, Construction, and Testing of Lightweight X-ray Mirror Modules

    Science.gov (United States)

    McClelland, Ryan S.; Biskach, Michael P.; Chan, Kai-Wing; Espina, Rebecca A.; Hohl, Bruce R.; Matson, Elizabeth A.; Saha, Timo C.; Zhang, William W.

    2013-01-01

    Lightweight and high resolution optics are needed for future space-based X-ray telescopes to achieve advances in high-energy astrophysics. The Next Generation X-ray Optics (NGXO) team at NASA GSFC is nearing mission readiness for a 10 arc-second Half Power Diameter (HPD) slumped glass mirror technology while laying the groundwork for a future 1-2 arc-second technology based on polished silicon mirrors. Technology Development Modules (TDMs) have been designed, fabricated, integrated with mirrors segments, and extensively tested to demonstrate technology readiness. Tests include X-ray performance, thermal vacuum, acoustic load, and random vibration. The thermal vacuum and acoustic load environments have proven relatively benign, while the random vibration environment has proven challenging due to large input amplification at frequencies above 500 Hz. Epoxy selection, surface preparation, and larger bond area have increased bond strength while vibration isolation has decreased vibration amplification allowing for space launch requirements to be met in the near term. The next generation of TDMs, which demonstrates a lightweight structure supporting more mirror segments, is currently being fabricated. Analysis predicts superior performance characteristics due to the use of E-60 Beryllium-Oxide Metal Matrix Composite material, with only a modest cost increase. These TDMs will be larger, lighter, stiffer, and stronger than the current generation. Preliminary steps are being taken to enable mounting and testing of 1-2 arc-second mirror segments expected to be available in the future. A Vertical X-ray Test Facility (VXTF) will minimize module gravity distortion and allow for less constrained mirror mounts, such as fully kinematic mounts. Permanent kinematic mounting into a modified TDM has been demonstrated to achieve 2 arc-second level distortion free alignment.

  8. Mechanical Properties of Fiber Reinforced Lightweight Concrete Containing Surfactant

    Directory of Open Access Journals (Sweden)

    Yoo-Jae Kim

    2010-01-01

    Full Text Available Fiber reinforced aerated lightweight concrete (FALC was developed to reduce concrete's density and to improve its fire resistance, thermal conductivity, and energy absorption. Compression tests were performed to determine basic properties of FALC. The primary independent variables were the types and volume fraction of fibers, and the amount of air in the concrete. Polypropylene and carbon fibers were investigated at 0, 1, 2, 3, and 4% volume ratios. The lightweight aggregate used was made of expanded clay. A self-compaction agent was used to reduce the water-cement ratio and keep good workability. A surfactant was also added to introduce air into the concrete. This study provides basic information regarding the mechanical properties of FALC and compares FALC with fiber reinforced lightweight concrete. The properties investigated include the unit weight, uniaxial compressive strength, modulus of elasticity, and toughness index. Based on the properties, a stress-strain prediction model was proposed. It was demonstrated that the proposed model accurately predicts the stress-strain behavior of FALC.

  9. The Development of Lightweight Commercial Vehicle Wheels Using Microalloying Steel

    Science.gov (United States)

    Lu, Hongzhou; Zhang, Lilong; Wang, Jiegong; Xuan, Zhaozhi; Liu, Xiandong; Guo, Aimin; Wang, Wenjun; Lu, Guimin

    Lightweight wheels can reduce weight about 100kg for commercial vehicles, and it can save energy and reduce emission, what's more, it can enhance the profits for logistics companies. The development of lightweight commercial vehicle wheels is achieved by the development of new steel for rim, the process optimization of flash butt welding, and structure optimization by finite element methods. Niobium micro-alloying technology can improve hole expansion rate, weldability and fatigue performance of wheel steel, and based on Niobium micro-alloying technology, a special wheel steel has been studied whose microstructure are Ferrite and Bainite, with high formability and high fatigue performance, and stable mechanical properties. The content of Nb in this new steel is 0.025% and the hole expansion rate is ≥ 100%. At the same time, welding parameters including electric upsetting time, upset allowance, upsetting pressure and flash allowance are optimized, and by CAE analysis, an optimized structure has been attained. As a results, the weight of 22.5in×8.25in wheel is up to 31.5kg, which is most lightweight comparing the same size wheels. And its functions including bending fatigue performance and radial fatigue performance meet the application requirements of truck makers and logistics companies.

  10. Impact of lightweight and conventional jackhammers on the operator.

    Science.gov (United States)

    Campbell-Kyureghyan, Naira; Singh, Gurjeet; Otieno, Wilkistar; Cooper, Karen

    2012-01-01

    Jackhammer manufacturers have recently developed lightweight (45-60 lbs) jackhammers intended to reduce the required lifting and pushing forces during operation. However, the vibration characteristics of the lightweight jackhammers and their effect on muscle activity are currently unknown. The objective of this study was to compare the measured vibration and muscle activity between: (i) conventional (90 lb) and light weight (60 lb) jackhammers, (ii) different pavement type/thickness combinations, and (iii) pneumatic and hydraulic jackhammers. Five jackhammers were tested on 4 and 6 inch thick asphalt and concrete pavements by four experienced operators. Analysis of the results revealed that both weight classes averaged 9.7 m/s(2) at the 20 Hz weighted 1/3 octave band frequency, and the TLV of daily exposure for either weight class of jackhammer was less than 1.5 hours/per day. There was an approximately 33% difference in vibration measured on the hand of the operators due to pavement thickness, 30% due pavement type, and no difference due to power source. Conventional jackhammers overall produced higher muscle activity than lightweight jackhammers. Although selection of the correct jackhammer for the job involves many factors including pavement type and thickness, the results of this research can be used to assist in selecting the appropriate jackhammer.

  11. Broadband low-frequency sound isolation by lightweight adaptive metamaterials

    Science.gov (United States)

    Liao, Yunhong; Chen, Yangyang; Huang, Guoliang; Zhou, Xiaoming

    2018-03-01

    Blocking broadband low-frequency airborne noises is highly desirable in lots of engineering applications, while it is extremely difficult to be realized with lightweight materials and/or structures. Recently, a new class of lightweight adaptive metamaterials with hybrid shunting circuits has been proposed, demonstrating super broadband structure-borne bandgaps. In this study, we aim at examining their potentials in broadband sound isolation by establishing an analytical model that rigorously combines the piezoelectric dynamic couplings between adaptive metamaterials and acoustics. Sound transmission loss of the adaptive metamaterial is investigated with respect to both the frequency and angular spectrum to demonstrate their sound-insulation effects. We find that efficient sound isolation can indeed be pursued in the broadband bi-spectrum for not only the case of the small resonator's periodicity where only one mode relevant to the mass-spring resonance exists, but also for the large-periodicity scenario, so that the total weight can be even lighter, in which the multiple plate-resonator coupling modes appear. In the latter case, the negative spring stiffness provided by the piezoelectric stack has been utilized to suppress the resonance-induced high acoustic transmission. Such kinds of adaptive metamaterials could open a new approach for broadband noise isolation with extremely lightweight structures.

  12. Ceramic/polymer functionally graded material (FGM) lightweight armor system

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; McClellan, K.J.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at room temperature. Thus, they were able to demonstrate the feasibility of producing boron carbide-aluminum and boron carbide-polymer functionally graded materials.

  13. Advantages and challenges of dissimilar materials in automotive lightweight construction

    Science.gov (United States)

    Weberpals, Jan-Philipp; Schmidt, Philipp A.; Böhm, Daniel; Müller, Steffen

    2015-03-01

    The core of future automotive lightweight materials is the joining technology of various material mixes. The type of joining will be essential, particularly in electrified propulsion systems, especially as an improved electrical energy transmission leads to a higher total efficiency of the vehicle. The most evident parts to start the optimization process are the traction battery, the electrical performance modules and the engines. Consequently aluminum plays a very central role for lightweight construction applications. However, the physical-technical requirements of components often require the combination with other materials. Thus the joining of mixed material connections is an essential key technology for many of the current developments, for example in the areas E-Mobility, solar energy and lightweight construction. Due to these advantages mixed material joints are already established in the automotive industry and laser beam remote welding is now a focus technology for mixed material connections. The secret of the laser welding process with mixed materials lies within the different areas of the melting phase diagram depending on the mixing ratio and the cooling down rate. According to that areas with unwanted, prim, intermetallic phases arise in the fusion zone. Therefore, laser welding of mixed material connections can currently only be used with additional filler in the automotive industry.

  14. Development of lightweight THUNDER with fiber composite layers

    Science.gov (United States)

    Yoon, Kwang J.; Shin, Sukjoon; Kim, Jusik; Park, Hoon C.; Kwak, Moon K.

    2000-06-01

    This paper is concerned with design, manufacturing and performance test of lightweight THUNDER using a top fiber composite layer with near-zero CTE, a PZT ceramic wafer and a bottom glass/epoxy layer with high CTE. The main point of this design is to replace the heavy metal layers of THUNDER by the lightweight fiber reinforced plastic layers without losing capabilities to generate high force and displacement. It is possible to save weight up to about 30 percent if we replace the metallic backing materials by the light fiber composite layer. We can also have design flexibility by selecting the fiber direction and the size of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use epoxy resin prepreg system. Glass/epoxy prepregs, a ceramic wafer with electrode surfaces, and a graphite/epoxy prepreg were simply stacked and cured at an elevated temperature by following autoclave bagging process. It was found that the manufactured composite laminate device had a sufficient curvature after detaching form a flat mold. From experimental actuation tests, it was observed that the developed actuator could generate larger actuation displacement than THUNDER.

  15. The utilization of stone ash on cellular lightweight concrete

    Science.gov (United States)

    Karolina, R.; Sianipar, Y. G. C.

    2018-02-01

    Lightweight concrete brick is a brick which made of cement, sand, water, and foam as the basic composition. This brick are divided into 2, based on the foam used such as AAC (Autoclave Aerated Concrete) that use aluminium paste and CLC(Cellular Lightweight Concrete) that use foaming agent from BASF as its foaming material. In this trial, the lightweight brick that are ging to be use are the CLC with foaming agent as its foaming material with the mixture of stone ash that are produced by the Stone Crusher with spesific gravity 2666 kg/m3 as their partly sand substitution . In this research, the stone ash variant that are used are 10%, 15%, and 20% from the amount of sand that planned before. After casting, the result of the 10% will receive a reduction of compressive strength while an increasing in absorption as 25.07% and 39.005% and the 15% variant will recieve a reduction of compressive strength as much as 65.8% and a reduction of absorption as much as 17.441% and the 20% variant will recieve a reduction of compressive strength as much as 67.4% while an increasing of absorption as much as 17.956%.

  16. Lightweight S-Box Architecture for Secure Internet of Things

    Directory of Open Access Journals (Sweden)

    A. Prathiba

    2018-01-01

    Full Text Available Lightweight cryptographic solutions are required to guarantee the security of Internet of Things (IoT pervasiveness. Cryptographic primitives mandate a non-linear operation. The design of a lightweight, secure, non-linear 4 × 4 substitution box (S-box suited to Internet of Things (IoT applications is proposed in this work. The structure of the 4 × 4 S-box is devised in the finite fields GF (24 and GF ((222. The finite field S-box is realized by multiplicative inversion followed by an affine transformation. The multiplicative inverse architecture employs Euclidean algorithm for inversion in the composite field GF ((222. The affine transformation is carried out in the field GF (24. The isomorphic mapping between the fields GF (24 and GF ((222 is based on the primitive element in the higher order field GF (24. The recommended finite field S-box architecture is combinational and enables sub-pipelining. The linear and differential cryptanalysis validates that the proposed S-box is within the maximal security bound. It is observed that there is 86.5% lesser gate count for the realization of sub field operations in the composite field GF ((222 compared to the GF (24 field. In the PRESENT lightweight cipher structure with the basic loop architecture, the proposed S-box demonstrates 5% reduction in the gate equivalent area over the look-up-table-based S-box with TSMC 180 nm technology.

  17. Aperture referral in dioptric systems with stigmatic elements

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2012-12-01

    Full Text Available A previous paper develops the general theory of aperture referral in linear optics and shows how several ostensibly distinct concepts, including the blur patch on the retina, the effective corneal patch, the projective field and the field of view, are now unified as particular applications of the general theory.  The theory allows for astigmatism and heterocentricity.  Symplecticity and the generality of the approach, however, make it difficult to gain insight and mean that the material is not accessible to readers unfamiliar with matrices and linear algebra. The purpose of this paper is to examine whatis, perhaps, the most important special case, that in which astigmatism is ignored.  Symplecticity and, hence, the mathematics become greatly simplified. The mathematics reduces largely to elementary vector algebra and, in some places, simple scalar algebra and yet retains the mathematical form of the general approach.  As a result the paper allows insight into and provides a stepping stone to the general theory.  Under referral an aperture under-goes simple scalar magnification and transverse translation.  The paper pays particular attention to referral to transverse planes in the neighbourhood of a focal point where the magnification may be positive, zero or negative.  Circular apertures are treated as special cases of elliptical apertures and the meaning of referred apertures of negative radius is explained briefly. (S Afr Optom 2012 71(1 3-11

  18. Direct aperture optimization for online adaptive radiation therapy

    International Nuclear Information System (INIS)

    Mestrovic, Ante; Milette, Marie-Pierre; Nichol, Alan; Clark, Brenda G.; Otto, Karl

    2007-01-01

    This paper is the first investigation of using direct aperture optimization (DAO) for online adaptive radiation therapy (ART). A geometrical model representing the anatomy of a typical prostate case was created. To simulate interfractional deformations, four different anatomical deformations were created by systematically deforming the original anatomy by various amounts (0.25, 0.50, 0.75, and 1.00 cm). We describe a series of techniques where the original treatment plan was adapted in order to correct for the deterioration of dose distribution quality caused by the anatomical deformations. We found that the average time needed to adapt the original plan to arrive at a clinically acceptable plan is roughly half of the time needed for a complete plan regeneration, for all four anatomical deformations. Furthermore, through modification of the DAO algorithm the optimization search space was reduced and the plan adaptation was significantly accelerated. For the first anatomical deformation (0.25 cm), the plan adaptation was six times more efficient than the complete plan regeneration. For the 0.50 and 0.75 cm deformations, the optimization efficiency was increased by a factor of roughly 3 compared to the complete plan regeneration. However, for the anatomical deformation of 1.00 cm, the reduction of the optimization search space during plan adaptation did not result in any efficiency improvement over the original (nonmodified) plan adaptation. The anatomical deformation of 1.00 cm demonstrates the limit of this approach. We propose an innovative approach to online ART in which the plan adaptation and radiation delivery are merged together and performed concurrently--adaptive radiation delivery (ARD). A fundamental advantage of ARD is the fact that radiation delivery can start almost immediately after image acquisition and evaluation. Most of the original plan adaptation is done during the radiation delivery, so the time spent adapting the original plan does not

  19. Design and Experimental Verification of Deployable/Inflatable Ultra-Lightweight Structures

    Science.gov (United States)

    Pai, P. Frank

    2004-01-01

    Because launch cost of a space structural system is often proportional to the launch volume and mass and there is no significant gravity in space, NASA's space exploration programs and various science missions have stimulated extensive use of ultra-lightweight deployable/inflatable structures. These structures are named here as Highly Flexible Structures (HFSs) because they are designed to undergo large displacements, rotations, and/or buckling without plastic deformation under normal operation conditions. Except recent applications to space structural systems, HFSs have been used in many mechanical systems, civil structures, aerospace vehicles, home appliances, and medical devices to satisfy space limitations, provide special mechanisms, and/or reduce structural weight. The extensive use of HFSs in today's structural engineering reveals the need of a design and analysis software and a database system with design guidelines for practicing engineers to perform computer-aided design and rapid prototyping of HFSs. Also to prepare engineering students for future structural engineering requires a new and easy-to- understand method of presenting the complex mathematics of the modeling and analysis of HFSs. However, because of the high flexibility of HFSs, many unique challenging problems in the modeling, design and analysis of HFSs need to be studied. The current state of research on HFSs needs advances in the following areas: (1) modeling of large rotations using appropriate strain measures, (2) modeling of cross-section warpings of structures, (3) how to account for both large rotations and cross- section warpings in 2D (two-dimensional) and 1D structural theories, (4) modeling of thickness thinning of membranes due to inflation pressure, pretension, and temperature change, (5) prediction of inflated shapes and wrinkles of inflatable structures, (6) development of efficient numerical methods for nonlinear static and dynamic analyses, and (7) filling the gap between

  20. Integrated Optical Synthetic Aperture Radar Processor.

    Science.gov (United States)

    1987-09-01

    acoustooptic cell was employed to input each radar return into a time-and-space integrating optical architecture comprised of several lenses, a CCD area array...acoustooptic cell and parallel rib waveguide structure. During the course of the literature survey, we became aware of an elegant and poten- tially profound...wave.) scatterer at (f , A(t) is the far-field pattern of the antenna. From the geometry of Si. 1. R can be written as [I-2R,/c - nT1 r(t) = A(nT) rectj

  1. Permeability and dispersivity of variable-aperture fracture systems

    International Nuclear Information System (INIS)

    Tsang, Y.W.; Tsang, C.F.

    1990-01-01

    A number of recent experiments have pointed out the need of including the effects of aperture variation within each fracture in predicting flow and transport properties of fractured media. This paper introduces a new approach in which medium properties, such as the permeability to flow and dispersivity in tracer transport, are correlated to only three statistical parameters describing the fracture aperture probability distribution and the aperture spatial correlation. We demonstrate how saturated permeability and relative permeabilities for flow, as well as dispersion for solute transport in fractures may be calculated. We are in the process of examining the applicability of these concepts to field problems. Results from the evaluation and analysis of the recent Stripa-3D field data are presented. 13 refs., 10 figs

  2. Variable aperture-based ptychographical iterative engine method.

    Science.gov (United States)

    Sun, Aihui; Kong, Yan; Meng, Xin; He, Xiaoliang; Du, Ruijun; Jiang, Zhilong; Liu, Fei; Xue, Liang; Wang, Shouyu; Liu, Cheng

    2018-02-01

    A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  3. Variable aperture-based ptychographical iterative engine method

    Science.gov (United States)

    Sun, Aihui; Kong, Yan; Meng, Xin; He, Xiaoliang; Du, Ruijun; Jiang, Zhilong; Liu, Fei; Xue, Liang; Wang, Shouyu; Liu, Cheng

    2018-02-01

    A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches.

  4. Synthetic aperture integration (SAI) algorithm for SAR imaging

    Science.gov (United States)

    Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

    2013-07-09

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

  5. Central obscuration effects on optical synthetic aperture imaging

    Science.gov (United States)

    Wang, Xue-wen; Luo, Xiao; Zheng, Li-gong; Zhang, Xue-jun

    2014-02-01

    Due to the central obscuration problem exists in most optical synthetic aperture systems, it is necessary to analyze its effects on their image performance. Based on the incoherent diffraction limited imaging theory, a Golay-3 type synthetic aperture system was used to study the central obscuration effects on the point spread function (PSF) and the modulation transfer function (MTF). It was found that the central obscuration does not affect the width of the central peak of the PSF and the cutoff spatial frequency of the MTF, but attenuate the first sidelobe of the PSF and the midfrequency of the MTF. The imaging simulation of a Golay-3 type synthetic aperture system with central obscuration proved this conclusion. At last, a Wiener Filter restoration algorithm was used to restore the image of this system, the images were obviously better.

  6. The roles of frequency and aperture in linac accelerator design

    International Nuclear Information System (INIS)

    Farkas, Z.D.

    1989-01-01

    Expressions for accelerating structure parameters, including those that determine the peak and average power inputs required to attain a given gradient, are given as functions of aperture to wavelength ratio for a 2π/3 mode disk-loaded guide. The value of the wavelength to aperture ratio varies over a large range, corresponding to group velocities that vary from nearly zero to nearly the speed of light. The parameters exhibit proper asymptotic behavior in both limits. These parameters are benchmark values to which parameters for other modes and for other structure shapes can be compared. For example, it will be shown that the increased peak surface field to accelerating field ratio due to increased aperture to wavelength ratio can be reduced by shaping the iris profile. Structure shapes are varied not only to show possible improvement of structure parameters, but also to improve ease of mechanical fabrication and temperature control. 4 refs., 7 figs., 1 tab

  7. Deployable reflector configurations. [for space telescope

    Science.gov (United States)

    Meinel, A. B.; Meinel, M. P.; Woolf, N. J.

    1983-01-01

    Both the theoretical reasons for considering a non-circular format for the Large Deployable Reflector, and a potentially realizable concept for such a device, are discussed. The optimum systems for diffraction limited telescopes with incoherent detection have either a single filled aperture, or two such apertures as an interferometer to synthesize a larger aperture. For a single aperture of limited area, a reflector in the form of a slot can be used to give increased angular resolution. It is shown how a 20 x 8 meter telescope can be configured to fit the Space Shuttle bay, and deployed with relatively simple operations. The relationship between the sunshield design and the inclination of the orbit is discussed. The possible use of the LDR as a basic module to permit the construction of supergiant space telescopes and interferometers both for IR/submm studies and for the entire ultraviolet through mm wave spectral region is discussed.

  8. X-ray lenses with large aperture; Roentgenlinsen mit grosser Apertur

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Markus

    2010-07-01

    Up to now, most X-ray imaging setups are based on absorption contrast imaging. There is a demand for focused X-rays in many X-ray analysis applications, either to increase the resolution of an imaging system, or, to reduce the time effort of an experiment through higher photon flux. For photon energies higher than 15 keV refractive X-ray optics are more efficient in comparison to non-refractive X-ray optics. The aim of this work was to develop X-ray lenses with large apertures and high transparency. By increasing the number of refracting surfaces while removing unnecessary lens material such lenses have been developed. Utilizing this approach the overall beam deflection angle is large with respect to the lens material it propagates through and so the transparency of the lens is increased. Within this work, X-ray lenses consisting of several thousands of prisms with an edge length in the range of micrometers have been developed and fabricated by deep X-ray lithography. Deep X-ray lithography enables high precision microstrucures with smooth sidewalls and large aspect ratios. The aperture of high-transparency X-ray lenses made this way is greater than 1 mm. They are suitable for photon energies in the range of 8 keV to 24 keV and offer a focal width of smaller than 10 {mu}m at a transparency of around 40%. Furthermore, rolled X-ray lenses have been developed, that are made out of a microstructured polyimide film, which is cut according to the requirements regarding focal length and photon energy. The microstructured film is fabricated by molding, using an anisotropically etched silicon wafer as molding tool. Its mean roughness is in the range of nanometers. The film features prismatic structures, its surface topology is similar to an asparagus field. The measured diameter of the point focus was 18 {mu}m to 31 {mu}m, the calculated opticla efficiency was 37%. Future work will concentrate on increasing the aspect ratio of Prism Lenses and on increasing the rolling

  9. Direct-aperture optimization applied to selection of beam orientations in intensity-modulated radiation therapy

    International Nuclear Information System (INIS)

    Bedford, J L; Webb, S

    2007-01-01

    Direct-aperture optimization (DAO) was applied to iterative beam-orientation selection in intensity-modulated radiation therapy (IMRT), so as to ensure a realistic segmental treatment plan at each iteration. Nested optimization engines dealt separately with gantry angles, couch angles, collimator angles, segment shapes, segment weights and wedge angles. Each optimization engine performed a random search with successively narrowing step sizes. For optimization of segment shapes, the filtered backprojection (FBP) method was first used to determine desired fluence, the fluence map was segmented, and then constrained direct-aperture optimization was used thereafter. Segment shapes were fully optimized when a beam angle was perturbed, and minimally re-optimized otherwise. The algorithm was compared with a previously reported method using FBP alone at each orientation iteration. An example case consisting of a cylindrical phantom with a hemi-annular planning target volume (PTV) showed that for three-field plans, the method performed better than when using FBP alone, but for five or more fields, neither method provided much benefit over equally spaced beams. For a prostate case, improved bladder sparing was achieved through the use of the new algorithm. A plan for partial scalp treatment showed slightly improved PTV coverage and lower irradiated volume of brain with the new method compared to FBP alone. It is concluded that, although the method is computationally intensive and not suitable for searching large unconstrained regions of beam space, it can be used effectively in conjunction with prior class solutions to provide individually optimized IMRT treatment plans

  10. Parameter Optimization of Multi-Element Synthetic Aperture Imaging Systems

    Directory of Open Access Journals (Sweden)

    Vera Behar

    2007-03-01

    Full Text Available In conventional ultrasound imaging systems with phased arrays, the further improvement of lateral resolution requires enlarging of the number of array elements that in turn increases both, the complexity and the cost, of imaging systems. Multi-element synthetic aperture focusing (MSAF systems are a very good alternative to conventional systems with phased arrays. The benefit of the synthetic aperture is in reduction of the system complexity, cost and acquisition time. In a MSAF system considered in the paper, a group of elements transmit and receive signals simultaneously, and the transmit beam is defocused to emulate a single element response. The echo received at each element of a receive sub-aperture is recorded in the computer memory. The process of transmission/reception is repeated for all positions of a transmit sub-aperture. All the data recordings associated with each corresponding pair "transmit-receive sub-aperture" are then focused synthetically producing a low-resolution image. The final high-resolution image is formed by summing of the all low-resolution images associated with transmit/receive sub-apertures. A problem of parameter optimization of a MSAF system is considered in this paper. The quality of imaging (lateral resolution and contrast is expressed in terms of the beam characteristics - beam width and side lobe level. The comparison between the MSAF system described in the paper and an equivalent conventional phased array system shows that the MSAF system acquires images of equivalent quality much faster using only a small part of the power per image.

  11. Three dimensional fracture aperture and porosity distribution using computerized tomography

    Science.gov (United States)

    Wenning, Q.; Madonna, C.; Joss, L.; Pini, R.

    2017-12-01

    A wide range of geologic processes and geo-engineered applications are governed by coupled hydromechanical properties in the subsurface. In geothermal energy reservoirs, quantifying the rate of heat transfer is directly linked with the transport properties of fractures, underscoring the importance of fracture aperture characterization for achieving optimal heat production. In this context, coupled core-flooding experiments with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) provide a powerful method to make observations of these properties under representative geologic conditions. This study focuses on quantifying fracture aperture distribution in a fractured westerly granite core by using a recently developed calibration-free method [Huo et al., 2016]. Porosity is also estimated with the X-ray saturation technique using helium and krypton gases as saturating fluids, chosen for their high transmissibility and high CT contrast [e.g., Vega et al., 2014]. The westerly granite sample (diameter: 5 cm, length: 10 cm) with a single through-going rough-walled fracture was mounted in a high-pressure aluminum core-holder and placed inside a medical CT scanner for imaging. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated to have the desired effective pressure (0.5, 5, 7 and 10 MPa) under loading and unloading conditions. 3D reconstructions of the sample have been prepared in terms of fracture aperture and porosity at a maximum resolution of (0.24×0.24×1) mm3. Fracture aperture maps obtained independently using helium and krypton for the whole core depict a similar heterogeneous aperture field, which is also dependent on confining pressure. Estimates of the average hydraulic aperture from CT scans are in quantitative agreement with results from fluid flow experiments. However, the latter lack of the level of observational detail achieved through imaging, which further evidence the

  12. Analytical estimation of the dynamic apertures of circular accelerators

    International Nuclear Information System (INIS)

    Gao, J.

    2000-02-01

    By considering delta function sextupole, octupole, and deca-pole perturbations and using difference action-angle variable equations, we find some useful analytical formulae for the estimation of the dynamic apertures of circular accelerators due to single sextupole, single octupole, single deca-pole (single 2 m pole in general). Their combined effects are derived based on the Chirikov criterion of the onset of stochastic motions. Comparisons with numerical simulations are made, and the agreement is quite satisfactory. These formulae have been applied to determine the beam-beam limited dynamic aperture in a circular collider. (author)

  13. Metrology measurements for large-aperture VPH gratings

    Science.gov (United States)

    Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

    2013-09-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

  14. Synthetic Aperture Sequential Beamformation applied to medical imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is applied to medical ultrasound imaging using a multi element convex array transducer. The main motivation for SASB is to apply synthetic aperture techniques without the need for storing RF-data for a number of elements and hereby devise a system...... with a reduced system complexity. Using a 192 element, 3.5 MHz, λ-pitch transducer, it is demonstrated using tissue-phantom and wire-phantom measurements, how the speckle size and the detail resolution is improved compared to conventional imaging....

  15. Lightweight Brick by Carbon Ash from The Mixed Plastic Waste Treatment Plant

    OpenAIRE

    Chen Kuo-Wei

    2016-01-01

    This study was designed to investigate the mixed plastic waste from the production of light carbon ash bricks performance. The mixed waste plastic pyrolysis process generated waste - Carbon ash. After extrusion, a Lightweight brick was made by carbon ash, additive and Cement mortar. In general, the set compressive strength and insulation effect of lightweight bricks with carbon ash proportion for significant impact. The set water absorption and thermal conductivity of lightweight bricks with ...

  16. Flexible Graphene-based Energy Storage Devices for Space Application Project

    Science.gov (United States)

    Calle, Carlos I.

    2014-01-01

    Develop prototype graphene-based reversible energy storage devices that are flexible, thin, lightweight, durable, and that can be easily attached to spacesuits, rovers, landers, and equipment used in space.

  17. Universal Sample Preparation Module for Molecular Analysis in Space, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Lynntech proposes to develop and demonstrate the ability of a compact, light-weight, and automated universal sample preparation module (USPM) to process samples from...

  18. Multifunctional Shielding and Self-Healing HybridSil Smart Composites for Space, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NanoSonic has developed revolutionary multifunctional, super lightweight, self-healing and radiation shielding carbon fiber reinforced polymer (CFRP) composites as a...

  19. Lightweight Damage Tolerant, High-Temperature Radiators for Nuclear Power and Propulsion

    Science.gov (United States)

    Craven, Paul D.; SanSoucie, Michael P.

    2015-01-01

    NASA is increasingly emphasizing exploration to bodies beyond near-Earth orbit. New propulsion systems and new spacecraft are being built for these missions. As the target bodies get further out from Earth, high energy density systems, e.g., nuclear fusion, for propulsion and power will be advantageous. The mass and size of these systems, including supporting systems such as the heat exchange system, including thermal radiators, will need to be as small as possible. Conventional heat exchange systems are a significant portion of the total thermal management mass and size. Nuclear electric propulsion (NEP) is a promising option for high-speed, in-space travel due to the high energy density of nuclear fission power sources and efficient electric thrusters. Heat from the reactor is converted to power for use in propulsion or for system power. The heat not used in the power conversion is then radiated to space as shown in figure 1. Advanced power conversion technologies will require high operating temperatures and would benefit from lightweight radiator materials. Radiator performance dictates power output for nuclear electric propulsion systems. Pitch-based carbon fiber materials have the potential to offer significant improvements in operating temperature, thermal conductivity, and mass. These properties combine to allow significant decreases in the total mass of the radiators and significant increases in the operating temperature of the fins. A Center-funded project at NASA Marshall Space Flight Center has shown that high thermal conductivity, woven carbon fiber fins with no matrix material, can be used to dissipate waste heat from NEP systems and because of high specific power (kW/kg), will require less mass and possibly less total area than standard metal and composite radiator fins for radiating the same amount of heat. This project uses an innovative approach to reduce the mass and size required for the thermal radiators to the point that in-space NEP and power

  20. Meta-shell Approach for Constructing Lightweight and High Resolution X-Ray Optics

    Science.gov (United States)

    McClelland, Ryan S.

    2016-01-01

    Lightweight and high resolution optics are needed for future space-based x-ray telescopes to achieve advances in high-energy astrophysics. Past missions such as Chandra and XMM-Newton have achieved excellent angular resolution using a full shell mirror approach. Other missions such as Suzaku and NuSTAR have achieved lightweight mirrors using a segmented approach. This paper describes a new approach, called meta-shells, which combines the fabrication advantages of segmented optics with the alignment advantages of full shell optics. Meta-shells are built by layering overlapping mirror segments onto a central structural shell. The resulting optic has the stiffness and rotational symmetry of a full shell, but with an order of magnitude greater collecting area. Several meta-shells so constructed can be integrated into a large x-ray mirror assembly by proven methods used for Chandra and XMM-Newton. The mirror segments are mounted to the meta-shell using a novel four point semi-kinematic mount. The four point mount deterministically locates the segment in its most performance sensitive degrees of freedom. Extensive analysis has been performed to demonstrate the feasibility of the four point mount and meta-shell approach. A mathematical model of a meta-shell constructed with mirror segments bonded at four points and subject to launch loads has been developed to determine the optimal design parameters, namely bond size, mirror segment span, and number of layers per meta-shell. The parameters of an example 1.3 m diameter mirror assembly are given including the predicted effective area. To verify the mathematical model and support opto-mechanical analysis, a detailed finite element model of a meta-shell was created. Finite element analysis predicts low gravity distortion and low thermal distortion. Recent results are discussed including Structural Thermal Optical Performance (STOP) analysis as well as vibration and shock testing of prototype meta-shells.