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Sample records for active main reflector

  1. Secondary pattern computation of an arbitrarily shaped main reflector

    NASA Technical Reports Server (NTRS)

    Lam, P. T. C.; Lee, S. W.; Acosta, R.

    1984-01-01

    The secondary pattern of a perfectly conducting offset main reflector being illuminated by a point feed at an arbitrary location was studied. The method of analysis is based upon the application of the Fast Fourier Transform (FFT) to the aperture fields obtained using geometrical optics (GO) and geometrical theory of diffraction (GTD). Key features of the reflector surface is completely arbitrary, the incident field from the feed is most general with arbitrary polarization and location, and the edge diffraction is calculated by either UAT or by UTD. Comparison of this technique for an offset parabolic reflector with the Jacobi-Bessel and Fourier-Bessel techniques shows good agreement. Near field, far field, and scan data of a large reflector are presented.

  2. Design of subreflectors to compensate for Cassegrain main reflector deformations

    NASA Astrophysics Data System (ADS)

    Milner, M. O.; Bates, R. H. T.

    1980-10-01

    There can be economic and technical advantages in compensating for measured errors in the main reflector of a Cassegrain antenna by refiguring the subreflector. A design procedure (realized as a software package) is described whereby, given a set of measured main reflector errors, ordinates defining a comprehensively checked redesign for the subreflector are provided. Efficient ray tracing and interpolation algorithms are included in the software package, which is illustrated with numerical results indicating the improvements in antenna performance to be expected when a Cassegrain subreflector is redesigned.

  3. Secondary pattern computation of an arbitrarily shaped main reflector

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Lam, P. T. C.; Acosta, R. J.

    1985-01-01

    The secondary pattern of a perfectly conducting offset main reflector being illuminated by a point feed at an arbitrary location is studied. The method of analysis is based upon the application of the Fast Fourier Transform (FFT) to the aperture fields obtained using geometrical optics (GO) and geometrical theory of diffraction (GTD). Key features of the present work are (1) the reflector surface is completely arbitrary, (2) the incident field from the feed is most general with arbitrary polarization and location, and (3) the edge diffraction is calculated by either UAT or by UTD. Comparison of this technique for an offset parabolic reflector with the Jacobi-Bessel and Fourier-Bessel techniques shows good agreement. Near field, far field, and scan data of a large refelctor are presented.

  4. Main-Reflector Manufacturing Technology for the Deep Space Optical Communications Ground Station

    NASA Astrophysics Data System (ADS)

    Britcliffe, M. J.; Hoppe, D. J.

    2001-01-01

    The Deep Space Network (DSN) has plans to develop a 10-m-diameter optical communications receiving station. The system uses the direct detection technique, which has much different requirements from a typical astronomical telescope. The receiver must operate in daylight and nighttime conditions. This imposes special requirements on the optical system to reject stray light from the Sun and other sources. One of the biggest challenges is designing a main-reflector surface that meets these requirements and can be produced at a reasonable cost. The requirements for the performance of the reflector are presented. To date, an aspherical primary reflector has been assumed. A reflector with a spherical reflector has a major cost advantage over an aspherical design, with no sacrifice in performance. A survey of current manufacturing techniques for optical mirrors of this type was performed. Techniques including solid glass, lightweight glass, diamond-turned aluminum, and composite mirrors were investigated.

  5. Control of active reflector system for radio telescope

    NASA Astrophysics Data System (ADS)

    Zhou, Guo-hua; Li, Guo-ping; Zhang, Yong; Zhang, Zhen-chao

    2016-10-01

    According to the control requirements of the active reflector surface in the 110 m radio telescope at QiTai(QTT) Xinjiang, a new displacement actuator and a new displacement control system were designed and manufactured and then their characteristics were tested by a dual-frequency laser interferometer in the micro-displacement laboratory. The displacement actuator was designed by a scheme of high precision worm and roller screw structures, and the displacement control system was based on a ARM micro-processor. Finally, the S curve acceleration control methods were used to design the hardware platform and software algorithm for the active reflection surface of the control system. The test experiments were performed based on the laser metrology system on an active reflector close-loop antenna prototype for large radio telescope. Experimental results indicate that it achieves a 30 mm working stroke and 5 μm RMS motion resolution. The accuracy (standard deviation) is 3.67 mm, and the error between the determined and theoretical values is 0.04% when the rated load is 300 kg, the step is 2 mm and the stroke is 30mm. Furthermore, the active reflector integrated system was tested by the laser sensors with the accuracy of 0.25 μm RMS on 4-panel radio telescope prototype, the measurement results show that the integrated precision of the active reflector closed-loop control system is less than 5 μm RMS, and well satisfies the technical requirements of active reflector control system of the QTT radio telescope in 3 mm wavelength.

  6. Correcting Thermal Deformations in an Active Composite Reflector

    NASA Technical Reports Server (NTRS)

    Bradford, Samuel C.; Agnes, Gregory S.; Wilkie, William K.

    2011-01-01

    Large, high-precision composite reflectors for future space missions are costly to manufacture, and heavy. An active composite reflector capable of adjusting shape in situ to maintain required tolerances can be lighter and cheaper to manufacture. An active composite reflector testbed was developed that uses an array of piezoelectric composite actuators embedded in the back face sheet of a 0.8-m reflector panel. Each individually addressable actuator can be commanded from 500 to +1,500 V, and the flatness of the panel can be controlled to tolerances of 100 nm. Measuring the surface flatness at this resolution required the use of a speckle holography interferometer system in the Precision Environmental Test Enclosure (PETE) at JPL. The existing testbed combines the PETE for test environment stability, the speckle holography system for measuring out-of-plane deformations, the active panel including an array of individually addressable actuators, a FLIR thermal camera to measure thermal profiles across the reflector, and a heat source. Use of an array of flat piezoelectric actuators to correct thermal deformations is a promising new application for these actuators, as is the use of this actuator technology for surface flatness and wavefront control. An isogrid of these actuators is moving one step closer to a fully active face sheet, with the significant advantage of ease in manufacturing. No extensive rib structure or other actuation backing structure is required, as these actuators can be applied directly to an easy-to-manufacture flat surface. Any mission with a surface flatness requirement for a panel or reflector structure could adopt this actuator array concept to create lighter structures and enable improved performance on orbit. The thermal environment on orbit tends to include variations in temperature during shadowing or changes in angle. Because of this, a purely passive system is not an effective way to maintain flatness at the scale of microns over several

  7. Multiphysics modeling and uncertainty quantification for an active composite reflector

    NASA Astrophysics Data System (ADS)

    Peterson, Lee D.; Bradford, S. C.; Schiermeier, John E.; Agnes, Gregory S.; Basinger, Scott A.

    2013-09-01

    A multiphysics, high resolution simulation of an actively controlled, composite reflector panel is developed to extrapolate from ground test results to flight performance. The subject test article has previously demonstrated sub-micron corrected shape in a controlled laboratory thermal load. This paper develops a model of the on-orbit performance of the panel under realistic thermal loads, with an active heater control system, and performs an uncertainty quantification of the predicted response. The primary contribution of this paper is the first reported application of the Sandia developed Sierra mechanics simulation tools to a spacecraft multiphysics simulation of a closed-loop system, including uncertainty quantification. The simulation was developed so as to have sufficient resolution to capture the residual panel shape error that remains after the thermal and mechanical control loops are closed. An uncertainty quantification analysis was performed to assess the predicted tolerance in the closed-loop wavefront error. Key tools used for the uncertainty quantification are also described.

  8. Active feed array compensation for reflector antenna surface distortions. Ph.D. Thesis - Akron Univ., Ohio

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.

    1988-01-01

    The feasibility of electromagnetic compensation for reflector antenna surface distortions is investigated. The performance characteristics of large satellite communication reflector antenna systems degrade as the reflector surface distorts, mainly due to thermal effects from solar radiation. The technique developed can be used to maintain the antenna boresight directivity and sidelobe level independent of thermal effects on the reflector surface. With the advent of monolithic microwave integrated circuits (MMIC), a greater flexibility in array fed reflector antenna systems can be achieved. MMIC arrays provide independent control of amplitude and phase for each of the many radiating elements in the feed array. By assuming a known surface distortion profile, a simulation study is carried out to examine the antenna performance as a function of feed array size and number of elements. Results indicate that the compensation technique can effectively control boresight directivity and sidelobe level under peak surface distortion in the order of tenth of a wavelength.

  9. Case study of active array feed compensation with sidelobe control for reflector surface distortion

    NASA Technical Reports Server (NTRS)

    Acosta, R. J.; Zaman, A. J. M.; Bobinsky, E. A.; Cherrette, A. R.; Lee, S. W.

    1988-01-01

    The feasibility of electromagnetically compensating for reflector surface distortions has been investigated. The performance characteristics (gain, sidelobe levels, etc.) of large communication antenna systems degrade as the reflector surface distorts mainly due to thermal effects from a varying solar flux. The techniques described in this report can be used to maintain the design performance characteristics independently of thermal effects on the reflector surface. With the advent of monolithic microwave integrated circuits (MMIC), a greater flexibility in array-fed reflector system design can be achieved. MMIC arrays provide independent control of amplitude and phase for each of many radiating elements of the feed array. It is assumed that the surface characteristics (x,y,z, its first and second derivatives) under distorted conditions are known.

  10. Rapid prototyping of reflectors for vehicle lighting using laser activated remote phosphor

    NASA Astrophysics Data System (ADS)

    Lachmayer, Roland; Kloppenburg, Gerolf; Wolf, Alexander

    2015-03-01

    Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class vehicles mainly use HID or LED as light source. As a further step in this development laser diode based systems offer high luminance, efficiency and allow the realization of new styling concepts and new dynamic lighting functions. These white laser diode systems can either be realized by mixing different spectral sources or by combining diodes with specific phosphors. Based on the approach of generating light using a laser and remote phosphor, lighting modules are manufactured. Four blue laser diodes (450 nm) are used to activate a phosphor coating and thus to achieve white light. A segmented paraboloid reflector generates the desired light distribution for an additional car headlamp. We use high speed milling and selective laser melting to build the reflector system for this lighting module. We compare the spectral reflection grade of these materials. Furthermore the generated modules are analyzed regarding their efficiency and light distribution. The use of Rapid Prototyping technologies allows an early validation of the chosen concept and is supposed to reduce cost and time in the product development process significantly. Therefor we discuss costs and times of the applied manufacturing technologies.

  11. Extravehicular activity compatibility evaluation of developmental hardware for assembly and repair of precision reflectors

    NASA Technical Reports Server (NTRS)

    Heard, Walter L., Jr.; Lake, Mark S.; Bush, Harold G.; Jensen, J. Kermit; Phelps, James E.; Wallsom, Richard E.

    1992-01-01

    This report presents results of tests performed in neutral buoyancy by two pressure-suited test subjects to simulate Extravehicular Activity (EVA) tasks associated with the on-orbit construction and repair of a precision reflector spacecraft. Two complete neutral buoyancy assemblies of the test article (tetrahedral truss with three attached reflector panels) were performed. Truss joint hardware, two different panel attachment hardware concepts, and a panel replacement tool were evaluated. The test subjects found the operation and size of the truss joint hardware to be acceptable. Both panel attachment concepts were found to be EVA compatible, although one concept was judged by the test subjects to be considerably easier to operate. The average time to install a panel from a position within arm's reach of the test subjects was 1 min 14 sec. The panel replacement tool was used successfully to demonstrate the removal and replacement of a damaged reflector panel in 10 min 25 sec.

  12. Active member vibration control for a 4 meter primary reflector support structure

    NASA Technical Reports Server (NTRS)

    Umland, J. W.; Chen, G.-S.

    1992-01-01

    The design and testing of a new low voltage piezoelectric active member with integrated load cell and displacement sensor is described. This active member is intended for micron level vibration and structural shape control of the Precision Segmented Reflector test-bed. The test-bed is an erectable 4 meter diameter backup support truss for a 2.4 meter focal length parabolic reflector. Active damping of the test-bed is then demonstrated using the newly developed active members. The control technique used is referred to as bridge feedback. With this technique the internal sensors are used in a local feedback loop to match the active member's input impedance to the structure's load impedance, which then maximizes vibrational energy dissipation. The active damping effectiveness is then evaluated from closed loop frequency responses.

  13. Multiple Reflector Scanning Antennas

    NASA Astrophysics Data System (ADS)

    Shen, Bing

    Narrow beamwidth antenna systems are important to remote sensing applications and point-to-point communication systems. In many applications the main beam of the antenna radiation pattern must be scannable over a region of space. Scanning by mechanically skewing the entire antenna assembly is difficult and in many situations is unacceptable. Performance during scan is, of course, also very important. Traditional reflector systems employing the well-focused paraboloidal -shaped main reflector accomplish scan by motion of a few feeds, or by phase steering a focal plane feed array. Such scanning systems can experience significant gain loss. Traditional reflecting systems with a spherical main reflector have low aperture efficiency and poor side lobe and cross polarization performance. This dissertation introduces a new approach to the design of scanning spherical reflector systems, in which the performance weaknesses of high cross polarization and high side lobe levels are avoided. Moreover, the low aperture utilization common in spherical reflectors is overcome. As an improvement to this new spherical main reflector configuration, a flat mirror reflector is introduced to minimize the mechanical difficulties to scan the main beam. In addition to the reflector system design, reflector antenna performance evaluation is also important. The temperature resolution issue important for earth observation radiometer antennas is studied, and a new method to evaluate and optimize such temperature resolution is introduced.

  14. Activities with Goto 45-CM Reflector at Bosscha Observatory, Lembang, Indonesia: Results and Aspects for Future Development

    NASA Astrophysics Data System (ADS)

    Malasan, H. L.

    In 1989 a 45-cm telescope of a cassegrainian type was installed, tested and commissioned at the Bosscha Observatory, Institut Teknologi Bandung. It was immediately put into use for UBV photometric observations of close binary systems. While the main function of the telescope was for photometric observations, the versatile design inherent to a reflector made possible to include a spectrograph which spectral dispersion could match the MK spectral classification. Activities related both to education and research conducted using this reflector since its installation comprise of scientific (photometry, spectroscopy, imagery) and experiment in instrumentation (fiber-fed spectrograph, CCD camera insitu testing). An important side result of the photometric observations is atmospheric study based on long-term atmospheric extionction coefficients. A multidiscipline approach, involving meteorologist and mathematiciants, on the study of natural and antrophogenic pollution of the atmosphere over Lembang has been recently undertaken. At present the telescope is, however, suffered from obsolete technology in its control functions. This has hampered it to be utilized fully, and therefore a plan to upgrade and extend the capability of the telescope has been made. The background, activities and results with emphasize to the collaborative work will be presented. Aspects for future development of the telescope and its auxiliary instruments will be discussed.

  15. Solar reflector

    SciTech Connect

    Stone, D. C.

    1981-02-17

    A solar reflector having a flexible triangular reflective sheet or membrane for receiving and reflecting solar energy therefrom. The reflector is characterized by the triangular reflective sheet which is placed under tension thereby defining a smooth planar surface eliminating surface deflection which heretofore has reduced the efficiency of reflectors or heliostats used in combination for receiving and transmitting solar energy to an absorber tower.

  16. Monitoring glaciers and indications of subglacial volcanic activity using small-scale Top-Hat reflectors - An IsViews experiment on Myrdalsjökull, Iceland

    NASA Astrophysics Data System (ADS)

    Minet, Christian; Duque Biarge, Sergi; Jaenicke, Julia; Münzer, Ulrich; Mayer, Christoph; Franke, Jonas; Guðmundsson, Águst; Parizzi, Alessandro; Fritz, Thomas; Eineder, Michael

    2014-05-01

    Subglacial volcanic eruptions often provide indications of activity some time before the actual catastrophic event. Surface undulations appear on top of the ice cap and meltwater torrents can occur at the glacier margin. Even large scale uplifts of ice caps have been observed. Within the project IsViews a processing chain, based on high spatially and temporally resolved remote sensing imagery, will be developed in order to automatically identify such early indications. The main data used for this analysis are acquired by the TerraSAR-X, TanDEM-X and RapidEye satellites. First investigations concerning the feasibility of the near real-time warning system and the general baseline conditions are carried out on two large plateau glaciers in southern Iceland, namely Mördalsjökull and Vatnajökull. Within the 2013 IsViews field work an experiment was started in order to test a new way of glacier monitoring. Two test sites were established on the Mördalsjökull ice cap (one at the equilibrium line and one below), each consisting of a permanent GPS station and two nearby RADAR reflectors. These RADAR reflectors are specially designed Top-Hat reflectors, which are cheap to manufacture, small (50 cm diameter) and lightweight and therefore easy to handle, transport and deploy. Their special design makes them visible in SAR images independent of orientation, so different acquisition geometries and even different sensors can be used. The drawback of the small, low reflecting Top-Hat can be overcome by using the newly implemented Staring Spotlight Mode of the German SAR Satellite TerraSAR-X, providing an unprecedented resolution of down to 20 cm in the azimuth direction. The reflectors, as point targets, allow absolute positioning within the cm-level in the TerraSAR-X data. Time series of SAR data can be used to derive position and altitude changes of the reflector itself and possibly even melting rates by exploiting the different signal paths. The visibility of the Top

  17. Making Curved Frequency-Selective Microwave Reflectors

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory S.; Wu, Te-Kao

    1995-01-01

    Prototype curved lightweight dichroic microwave reflectors designed to be highly reflective in X and K(suba) frequency bands and highly transmissive in K(subu) and S bands. Conductive grid elements formed photolithographically on curved reflector surfaces. Intended for use as subreflectors of main paraboloidal antenna reflector to enable simultaneous operation in both prime-focus configuration in K(subu) and S bands and Cassegrain configuration in X and K(suba) bands. Basic concepts of reflectors described in "Frequency-Selective Microwave Reflectors" (NPO-18701). "Double Square-Loop Dichroic Microwave Reflector" (NPO-18676), "Triband Circular-Loop Dichroic Microwave Reflector" (NPO-18714), and "Improved Dichroic Microwave Reflector" (NPO-18664).

  18. Temperature Knowledge and Model Correlation for the Soil Moisture Active and Passive (SMAP) Reflector Mesh

    NASA Technical Reports Server (NTRS)

    Mikhaylov, Rebecca; Dawson, Douglas; Kwack, Eug

    2014-01-01

    NASA's Earth observing Soil Moisture Active & Passive (SMAP) Mission is scheduled to launch in November 2014 into a 685 km near-polar, sun synchronous orbit. SMAP will provide comprehensive global mapping measurements of soil moisture and freeze/thaw state in order to enhance understanding of the processes that link the water, energy, and carbon cycles. The primary objectives of SMAP are to improve worldwide weather and flood forecasting, enhance climate prediction, and refine drought and agriculture monitoring during its 3 year mission. The SMAP instrument architecture incorporates an L-band radar and an L-band radiometer which share a common feed horn and parabolic mesh reflector. The instrument rotates about the nadir axis at approximately 15 rpm, thereby providing a conically scanning wide swath antenna beam that is capable of achieving global coverage within 3 days. In order to make the necessary precise surface emission measurements from space, a temperature knowledge of 60 deg C for the mesh reflector is required. In order to show compliance, a thermal vacuum test was conducted using a portable solar simulator to illuminate a non flight, but flight-like test article through the quartz window of the vacuum chamber. The molybdenum wire of the antenna mesh is too fine to accommodate thermal sensors for direct temperature measurements. Instead, the mesh temperature was inferred from resistance measurements made during the test. The test article was rotated to five separate angles between 10 deg and 90 deg via chamber breaks to simulate the maximum expected on-orbit solar loading during the mission. The resistance measurements were converted to temperature via a resistance versus temperature calibration plot that was constructed from data collected in a separate calibration test. A simple thermal model of two different representations of the mesh (plate and torus) was created to correlate the mesh temperature predictions to within 60 deg C. The on-orbit mesh

  19. Reflector Surface Error Compensation in Dual-Reflector Antennas

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Imbriale, William

    2010-01-01

    By probing the field on a small subreflector at a minimal number of points, the main reflector surface errors can be obtained and subsequently used to design a phase-correction subreflector that can compensate for main reflector errors. The compensating phase-error profile across the subreflector can be achieved either by a surface deformation or by the use of an array of elements such as patch antennas that can cause a phase shift between the incoming and outgoing fields. The second option is of primary interest here, but the methodology can be applied to either case. The patch array is most easily implemented on a planar surface. Therefore, the example of a flat subreflector and a parabolic main reflector (a Newtonian dual reflector system) is considered in this work. The subreflector is assumed to be a reflector array covered with patch elements. The phase variation on a subreflector can be detected by a small number of receiving patch elements (probes). By probing the phase change at these few selected positions on the subreflector, the phase error over the entire surface can be recovered and used to change the phase of all the patch elements covering the subreflector plane to compensate for main reflector errors. This is accomplished by using a version of sampling theorem on the circular aperture. The sampling is performed on the phase-error function on the circular aperture of the main reflector by a method developed using Zernike polynomials. This method is based upon and extended from a theory previously proposed and applied to reflector aperture integration. This sampling method provides for an exact retrieval of the coefficients of up to certain orders in the expansion of the phase function, from values on a specifically calculated set of points in radial and azimuthal directions in the polar coordinate system, on the circular reflector aperture. The corresponding points on the subreflector are then obtained and, by probing the fields at these points, a

  20. Jet screech reduction with perforated flat reflector

    NASA Astrophysics Data System (ADS)

    Khan, Md. Tawhidul Islam; Teramoto, Kenbu; Matsuo, Shigeru; Setoguchi, Toshiaki

    2008-09-01

    In the present experimental study, investigations have been carried out to evaluate the performance of the new control technique of jet screech with different perforated flat reflectors. Mainly two types of porous flat reflectors had been used in the experiment. One reflector (reflector-V) designed for placing the reflector surface vertical to the jet axis, when, another type of reflector (reflector-H) designed for placing the reflecting surface horizontal to the jet axis. In both cases the reflectors had been placed at the nozzle (base tube with uniform cross-sectional area) exit. The diameter of the reflector-V was 15D when the diameter of the reflector-H was 10D. The porous area of the reflector-V was 6D and 4.5D for reflector-H where D indicated the diameter of the nozzle exit. The placement of the reflector at the exit of the nozzle reduces the sound pressure at the nozzle exit. Thus the muted sound can not excite the unstable disturbance at the nozzle exit and the loop of the feedback mechanism disappeared, finally, the generation of jet screech be cancelled. The suction space located at the back side of the porous surface of the reflector-V improves the efficiency of the screech control technique. However, in the case of reflector-H, the receptivity process of feedback loop had been controlled by reducing the disturbances at the effective shock fronts as well as at the nozzle exit. The performance of the proposed method was verified with a flat reflector concept and good performance in jet screech suppression has been confirmed in the case of porous reflector.

  1. Neutral buoyancy test evaluation of hardware and extravehicular activity procedures for on-orbit assembly of a 14 meter precision reflector

    NASA Astrophysics Data System (ADS)

    Heard, Walter L., Jr.; Lake, Mark S.

    1993-02-01

    A procedure that enables astronauts in extravehicular activity (EVA) to perform efficient on-orbit assembly of large paraboloidal precision reflectors is presented. The procedure and associated hardware are verified in simulated Og (neutral buoyancy) assembly tests of a 14 m diameter precision reflector mockup. The test article represents a precision reflector having a reflective surface which is segmented into 37 individual panels. The panels are supported on a doubly curved tetrahedral truss consisting of 315 struts. The entire truss and seven reflector panels were assembled in three hours and seven minutes by two pressure-suited test subjects. The average time to attach a panel was two minutes and three seconds. These efficient assembly times were achieved because all hardware and assembly procedures were designed to be compatible with EVA assembly capabilities.

  2. Neutral buoyancy test evaluation of hardware and extravehicular activity procedures for on-orbit assembly of a 14 meter precision reflector

    NASA Technical Reports Server (NTRS)

    Heard, Walter L., Jr.; Lake, Mark S.

    1993-01-01

    A procedure that enables astronauts in extravehicular activity (EVA) to perform efficient on-orbit assembly of large paraboloidal precision reflectors is presented. The procedure and associated hardware are verified in simulated Og (neutral buoyancy) assembly tests of a 14 m diameter precision reflector mockup. The test article represents a precision reflector having a reflective surface which is segmented into 37 individual panels. The panels are supported on a doubly curved tetrahedral truss consisting of 315 struts. The entire truss and seven reflector panels were assembled in three hours and seven minutes by two pressure-suited test subjects. The average time to attach a panel was two minutes and three seconds. These efficient assembly times were achieved because all hardware and assembly procedures were designed to be compatible with EVA assembly capabilities.

  3. Bifocal dual reflector antenna

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    A bifocal dual reflector antenna is similar to and has better scan capability than classical cassegrain reflector antenna. The method used in determining the reflector surfaces is a modification of a design method for the dielectric bifocal lens. The three dimensional dual reflector is obtained by first designing an exact (in geometrical optics sense) two-point corrected two dimensional reflector and then rotating it around its axis of symmetry. A point by point technique is used in computing the reflector surfaces. Computed radiation characteristics of the dual reflector are compared with those of a cassegrain reflector. The results confirm that the bifocal antenna has superior performance.

  4. Differential correction method applied to measurement of the FAST reflector

    NASA Astrophysics Data System (ADS)

    Li, Xin-Yi; Zhu, Li-Chun; Hu, Jin-Wen; Li, Zhi-Heng

    2016-08-01

    The Five-hundred-meter Aperture Spherical radio Telescope (FAST) adopts an active deformable main reflector which is composed of 4450 triangular panels. During an observation, the illuminated area of the reflector is deformed into a 300-m diameter paraboloid and directed toward a source. To achieve accurate control of the reflector shape, positions of 2226 nodes distributed around the entire reflector must be measured with sufficient precision within a limited time, which is a challenging task because of the large scale. Measurement of the FAST reflector makes use of stations and node targets. However, in this case the effect of the atmosphere on measurement accuracy is a significant issue. This paper investigates a differential correction method for total stations measurement of the FAST reflector. A multi-benchmark differential correction method, including a scheme for benchmark selection and weight assignment, is proposed. On-site evaluation experiments show there is an improvement of 70%-80% in measurement accuracy compared with the uncorrected measurement, verifying the effectiveness of the proposed method.

  5. Computer prediction of dual reflector antenna radiation properties

    NASA Technical Reports Server (NTRS)

    Christodoulou, C.

    1981-01-01

    A program for calculating radiation patterns for reflector antennas with either smooth analytic surfaces or with surfaces composed of a number of panels. Techniques based on the geometrical optics (GO) approach were used in tracing rays over the following regions: from a feed antenna to the first reflector surface (subreflector); from this reflector to a larger reflector surface (main reflector); and from the main reflector to a mathematical plane (aperture plane) in front of the main reflector. The equations of GO were also used to calculate the reflected field components for each ray making use of the feed radiation pattern and the parameters defining the surfaces of the two reflectors. These resulting fields form an aperture distribution which is integrated numerically to compute the radiation pattern for a specified set of angles.

  6. Shaped cassegrain reflector antenna. [design equations

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    Design equations are developed to compute the reflector surfaces required to produce uniform illumination on the main reflector of a cassegrain system when the feed pattern is specified. The final equations are somewhat simple and straightforward to solve (using a computer) compared to the ones which exist already in the literature. Step by step procedure for solving the design equations is discussed in detail.

  7. The Planck Telescope reflectors

    NASA Astrophysics Data System (ADS)

    Stute, Thomas

    2004-09-01

    The mechanical division of EADS-Astrium GmbH, Friedrichshafen is currently engaged with the development, manufacturing and testing of the advanced dimensionally stable composite reflectors for the ESA satellite borne telescope Planck. The objective of the ESA mission Planck is to analyse the first light that filled the universe, the cosmic microwave background radiation. Under contract of the Danish Space Research Institute and ESA EADS-Astrium GmbH is developing the all CFRP primary and secondary reflectors for the 1.5-metre telescope which is the main instrument of the Planck satellite. The operational frequency ranges from to 25 GHz to 1000 GHz. The demanding high contour accuracy and surface roughness requirements are met. The design provides the extreme dimensional stability required by the cryogenic operational environment at around 40 K. The elliptical off-axis reflectors display a classical lightweight sandwich design with CFRP core and facesheets. Isostatic mounts provide the interfaces to the telescope structure. Protected VDA provides the reflecting surface. The manufacturing is performed at the Friedrichshafen premises of EADS-Space Transportation GmbH, the former Dornier composite workshops. Advanced manufacturing technologies like true angle lay-up by CNC fibre placement and filament winding are utilized. The protected coating is applied at the CAHA facilities at the Calar Alto Observatory, Spain. The exhaustive environmental testing is performed at the facilities of IABG, Munich (mechanical testing) and for the cryo-optical tests at CSL Liege. The project is in advanced state with both Qualification Models being under environmental testing. The flight models will be delivered in 2004. The paper gives an overview over the requirements and the main structural features how these requirements are met. Special production aspects and available test results are reported.

  8. Advanced Manufacture of Reflectors

    SciTech Connect

    Angel, Roger

    2014-12-17

    The main project objective has been to develop an advanced gravity sag method for molding large glass solar reflectors with either line or point focus, and with long or short focal length. The method involves taking standard sized squares of glass, 1.65 m x 1.65 m, and shaping them by gravity sag into precision steel molds. The method is designed for high volume manufacture when incorporated into a production line with separate pre-heating and cooling. The performance objectives for the self-supporting glass mirrors made by this project include mirror optical accuracy of 2 mrad root mean square (RMS), requiring surface slope errors less than 1 mrad rms, a target not met by current production of solar reflectors. Our objective also included development of new methods for rapidly shaping glass mirrors and coating them for higher reflectivity and soil resistance. Reflectivity of 95% for a glass mirror with anti-soil coating was targeted, compared to the present ~94% with no anti-soil coating. Our mirror cost objective is ~$20/m2 in 2020, a significant reduction compared to the present ~$35/m2 for solar trough mirrors produced for trough solar plants.

  9. Beam diffraction by planar and parabolic reflectors

    NASA Astrophysics Data System (ADS)

    Suedan, Gibreel A.; Jull, Edward V.

    1991-04-01

    In the complex source point (CSP) technique, an omnidirectional source diffraction solution becomes that for a directive beam when the coordinates of the source position are given appropriate complex values. This is applied to include feed directivity in reflector edge diffraction. Solutions and numerical examples for planar strip and parabolic cylinder reflectors are given, including an offset parabolic reflector. The main beams of parabolic reflectors are calculated by aperture integration and the edge diffracted fields by uniform diffraction theory. In both cases, a complex source point feed in the near or far field of the reflector may be used in the pattern calculation, with improvements in accuracy in the lateral and spillover pattern lobes.

  10. An experimental study on reflector wave-front error correction using PZT actuators

    NASA Astrophysics Data System (ADS)

    Lan, Lan; Jiang, Shuidong; Zhou, Yang; Fang, Houfei; Wu, Zhigang; Du, Jianming

    2016-04-01

    An adaptive control system for correcting wave-front error of a CFRC reflector has been studied. Errors investigated in this paper were mainly introduced by fabrication and gravity. 72 Piezoelectric Ceramic Transducer (PZT) actuators were integrated to the CFRC reflector to conduct wave-front error control. The adaptive CFRC reflector was fixed on an optical platform without any external loads. The temperature and humidity were well controlled during the experimental study. The wave-front error correction algorithm is based on influence matrix approach coupled with least squares optimization method. The linear relationship between the PZT actuator's input voltage and the output displacement of the adaptive CFRC reflector surface is validated. A laser displacement sensor was used for measuring the displacements. The influence matrix was obtained experimentally by measuring the displacements of the associated points while each actuator was activated separately. The wave-front error and influence matrix were measured using a V-Stars photogrammetry system. Experimental investigation validated that this adaptive control system is capable to significantly reduce the reflector surface geometry error. Experimental results are correlated very well with simulation results which were obtained by using a multidisciplinary analytical approach. Conclusions of this study suggest that the adaptive CFRC reflector technology can provide a low cost method to significantly increase the precision of a CFRC reflector.

  11. Nuclear reactor reflector

    DOEpatents

    Hopkins, Ronald J.; Land, John T.; Misvel, Michael C.

    1994-01-01

    A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled.

  12. Nuclear reactor reflector

    DOEpatents

    Hopkins, R.J.; Land, J.T.; Misvel, M.C.

    1994-06-07

    A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled. 12 figs.

  13. Precision antenna reflector structures

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.

    1985-01-01

    The assembly of the Large Precise Reflector Infrared Telescope is detailed. Also given are the specifications for the Aft Cargo Carrier and the Large Precision Reflector structure. Packaging concepts and options, stowage depth and support truss geometry are also considered. An example of a construction scenario is given.

  14. Spacecraft reflectors thermomechanical analysis

    NASA Astrophysics Data System (ADS)

    Ponomarev, Viktor S.; Gerasimov, Alexander V.; Ponomarev, Sergey V.; Shendalev, Denis O.

    2015-01-01

    In this article, thermo-mechanical analysis results of the composite reflectors for the use on the geostationary Earth orbit possibility studies are described. The behavior of two different space reflector structures manufactured on composite materials is investigated. The estimates of reflecting surfaces RMS deviations for the two extreme cases orbital inclinations are presented.

  15. REFLECTOR FOR NEUTRONIC REACTORS

    DOEpatents

    Fraas, A.P.

    1963-08-01

    A reflector for nuclear reactors that comprises an assembly of closely packed graphite rods disposed with their major axes substantially perpendicular to the interface between the reactor core and the reflector is described. Each graphite rod is round in transverse cross section at (at least) its interface end and is provided, at that end, with a coaxial, inwardly tapering hole. (AEC)

  16. Gravity deformation measurements of 70m reflector surfaces

    NASA Technical Reports Server (NTRS)

    Brenner, Michael; Imbriale, William A.; Britcliffe, Michael K.

    2001-01-01

    Two of NASA's Deep Space Network (DSN) 70-meter reflectors are measured using a Leica TDM-5000 theodolite. The main reflector surface was measured at five elevation angles so that a gravity deformation model could be derived that described the main reflector distortions over the entire range of elevation angles. The report describes the measurement equipment and accuracy and the results derived from the data.

  17. Active Asteroids: Main-Belt Comets and Disrupted Asteroids

    NASA Astrophysics Data System (ADS)

    Hsieh, Henry H.

    2016-10-01

    The study of active asteroids has attracted a great deal of interest in recent years since the recognition of main-belt comets (which orbit in the main asteroid belt, but exhibit comet-like activity due to the sublimation of volatile ices) as a new class of comets in 2006, and the discovery of the first disrupted asteroids (which, unlike MBCs, exhibit comet-like activity due to a physical disruption such as an impact or rotational destabilization, not sublimation) in 2010. In this paper, I will briefly discuss key areas of interest in the study of active asteroids.

  18. Inflatable Reflector For Solar Power And Radio Communication

    NASA Technical Reports Server (NTRS)

    Sercel, Joel; Gilchriest, Carl; Ewell, Rich; Herman, Martin; Rascoe, Daniel L.; Nesmith, Bill J.

    1995-01-01

    Report proposes installation of lightweight inflatable reflector structure aboard spacecraft required to both derive power from sunlight and communicate with Earth by radio when apparent position of Earth is at manageably small angle from line of sight to Sun. Structure contains large-aperture paraboloidal reflector aimed toward Sun and concentrates sunlight onto photovoltaic power converter and acts as main reflector of spacecraft radio-communication system.

  19. Suzaku observations of Markarian 335: evidence for a distributed reflector

    NASA Astrophysics Data System (ADS)

    Larsson, J.; Miniutti, G.; Fabian, A. C.; Miller, J. M.; Reynolds, C. S.; Ponti, G.

    2008-03-01

    We report on a 151-ks net exposure Suzaku observation of the narrow-line Seyfert 1 galaxy Mrk 335. The 0.5-40 keV spectrum contains a broad Fe line, a strong soft excess below about 2 keV and a Compton hump around 20-30 keV. We find that a model consisting of a power law and two reflectors provides the best fit to the time-averaged spectrum. In this model, an ionized, heavily blurred, inner reflector produces most of the soft excess, while an almost neutral outer reflector (outside ~ 40rg) produces most of the Fe line emission. The spectral variability of the observation is characterized by spectral hardening at very low count rates. In terms of our power-law + two-reflector model it seems like this hardening is mainly caused by pivoting of the power law. The rms spectrum of the entire observation has the curved shape commonly observed in active galactic nuclei, although the shape is significantly flatter when an interval which does not contain any deep dip in the light curve is considered. We also examine a previous 133-ks XMM-Newton observation of Mrk 335. We find that the XMM-Newton spectrum can be fitted with a similar two-reflector model as the Suzaku data and we confirm that the rms spectrum of the observation is flat. The flat rms spectra, as well as the high-energy data from the Suzaku PIN detector, disfavour an absorption origin for the soft excess in Mrk 335.

  20. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.; Dunn, D.

    1992-01-01

    The topics covered include the following: (1) performance analysis of the Gregorian tri-reflector; (2) design and performance of the type 6 reflector antenna; (3) a new spherical main reflector system design; (4) optimization of reflector configurations using physical optics; (5) radiometric array design; and (7) beam efficiency studies.

  1. Evolution of Pre-Main Sequence Stellar Activity

    NASA Astrophysics Data System (ADS)

    Kuin, N. Paul

    The best known low mass pre-main sequence stars, the T Tauri stars. have very active chromospheres and show a variable emission line spectrum. There is a large variety in activity amongst than. Recently another type of pre-main sequence stars was identified which may be post T Tauri stars (PTTS) and were named 'naked T Tauri stars' (NTTS). These PTTS/NTTS are strong X-Ray sources, and do not have a T Tauri type spectrum. The age of these sources is comparable to those of the T Tauri stars, which implies that either the activity evolves much faster in pre-main sequence stars than the timescale in which they move towards the main sequence, or that an external source is responsible for their activity. We propose to obtain low resolution long- and short wavelength RE spectra of two of the PTTS/NTTS and of a T Tauri star of comparable activity. Archival data will be used from three other T Tauri stars having larger activity. The data will enable us to derive models for the chromosphere and transition region. Those will clarify whether there is a gradual change in activity, or a sudden one as way be caused by the closing up of an open magnetic field. Because they cover a large range in chromoshperic activity the models will enable us to improve the alfven wave wind models used for T Tau and RU Lup. In particular the question of the wave dissipation scale length and wave leakage will be considered.

  2. A dielectric omnidirectional reflector

    PubMed

    Fink; Winn; Fan; Chen; Michel; Joannopoulos; Thomas

    1998-11-27

    A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices.

  3. Deployable Reflector for Solar Cells

    NASA Technical Reports Server (NTRS)

    Johnson, K. L.

    1982-01-01

    Unfoldable-membrane-reflector concept leads to mobile photovoltaic generators. Hinged containers swing open for deployment, and counterbalance beam swings into position. Folded reflector membranes are unfolded as deployment mast is extended, until stretched out flat.

  4. Nuclear Transmutations in HFIR's Beryllium Reflector and Their Impact on Reactor Operation and Reflector Disposal

    SciTech Connect

    Chandler, David; Maldonado, G Ivan; Primm, Trent; Proctor, Larry Duane

    2012-01-01

    The High Flux Isotope Reactor located at the Oak Ridge National Laboratory utilizes a large cylindrical beryllium reflector that is subdivided into three concentric regions and encompasses the compact reactor core. Nuclear transmutations caused by neutron activation occur in the beryllium reflector regions, which leads to unwanted neutron absorbing and radiation emitting isotopes. During the past year, two topics related to the HFIR beryllium reflector were reviewed. The first topic included studying the neutron poison (helium-3 and lithium-6) buildup in the reflector regions and its affect on beginning-of-cycle reactivity. A new methodology was developed to predict the reactivity impact and estimated symmetrical critical control element positions as a function of outage time between cycles due to helium-3 buildup and was shown to be in better agreement with actual symmetrical critical control element position data than the current methodology. The second topic included studying the composition of the beryllium reflector regions at discharge as well as during decay to assess the viability of transporting, storing, and ultimately disposing the reflector regions currently stored in the spent fuel pool. The post-irradiation curie inventories were used to determine whether the reflector regions are discharged as transuranic waste or become transuranic waste during the decay period for disposal purposes and to determine the nuclear hazard category, which may affect the controls invoked for transportation and temporary storage. Two of the reflector regions were determined to be transuranic waste at discharge and the other region was determined to become transuranic waste in less than 2 years after being discharged due to the initial uranium content (0.0044 weight percent uranium). It was also concluded that all three of the reflector regions could be classified as nuclear hazard category 3 (potential for localized consequences only).

  5. The Corner Reflector.

    ERIC Educational Resources Information Center

    Harris, Whitney S., Jr.

    1983-01-01

    The nature of the corner reflector array left on the moon by the July 1969 Apollo astronauts is described. The array was used to reflect earth-originating laser beams back to earth, and yielded a more accurate determination (to within six inches) of distance from the earth to the moon. (MP)

  6. Modular reflector concept study

    NASA Technical Reports Server (NTRS)

    Vaughan, D. H.

    1981-01-01

    A study was conducted to evaluate the feasibility of space erecting a 100 meter paraboloidal radio frequency reflector by joining a number of individually deployed structural modules. Three module design concepts were considered: (1) the deployable cell module (DCM); (2) the modular paraboloidal erectable truss antenna (Mod-PETA); and (3) the modular erectable truss antenna (META). With the space shuttle (STS) as the launch system, the methodology of packaging and stowing in the orbiter, and of dispensing, deploying and joining, in orbit, were studied and the necessary support equipment identified. The structural performance of the completed reflectors was evaluated and their overall operational capability and feasibility were evaluated and compared. The potential of the three concepts to maintain stable shape in the space environment was determined. Their ability to operate at radio frequencies of 1 GHz and higher was assessed assuming the reflector surface to consist of a number of flat, hexagonal facets. A parametric study was performed to determine figure degradation as a function of reflector size, flat facet size, and f/D ratio.

  7. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  8. Large space reflector technology on the Space Station

    NASA Technical Reports Server (NTRS)

    Mankins, J. C.; Dickinson, R. M.; Freeland, R. E.; Marzwell, N. I.

    1986-01-01

    This paper discusses the role of the Space Station in the evolutionary development of large space reflector technology and the accommodation of mission systems which will apply large space reflectors during the late 1990s and the early part of the next century. Reflectors which range from 10 to 100 meters in size and which span the electromagnetic spectrum for applications that include earth communications, earth observations, astrophysics and solar physics, and deep space communications are discussed. The role of the Space Station in large space reflector technology development and system performance demonstration is found to be critical; that role involves the accommodation of a wide variety of technology demonstrations and operational activities on the Station, including reflector deployment and/or assembly, mechanical performance verification and configuration refinement, systematic diagnostics of reflector surfaces, structural dynamics and controls research, overall system performance characterization and modification (including both radio frequency field pattern measurements and required end-to-end system demonstrations), and reflector-to-spacecraft integration and staging. A unique facility for Space Station-based, large space reflector research and development is proposed. A preliminary concept for such a Space Station-based Large Space Reflector Facility (LSRF) is described.

  9. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Lapean, J.

    1993-01-01

    There were several tangible products that resulted from the reflector antenna research program. The initial technical effort was to develop techniques to compensate for distortions over the surface of the main reflector of a large reflector antenna system. An in-depth investigation of this problem resulted in a new technique for the electronic correction of surface errors. A journal article on the findings describe the use of the iterative sampling method. Shortly after the 'Mission to Planet Earth' program started, we began investigating the use of large reflector antennas in geostationary orbit for passive earth remote sensing. A study panel was coordinated by Virginia Tech to set technical goals for the effort. These were used to guide the design of several antennas. The original interest stemmed from an industrial (Reynolds Metals) need and currently involves work with industry (Prodelin Corporation) on high technology, low cost reflectors. The intervening years (1987 - 1993) is the period of this report and Virginia Tech's reflector antenna activity then was exclusively with NASA LaRC.

  10. Chromospheric Activity in Pre-Main-Sequence Stars

    NASA Astrophysics Data System (ADS)

    Simon, Theodore

    IUE observations of solar-type stars show a decline of chromospheric and TR emission with age. For main-sequence stars older than 100 million yr, this decay is exponential from a plateau defined by the youngest stars. At an age of ~1 million yr, the pre-main-sequence T Tauri stars have UV emission line fluxes some 2 orders of magnitude above the plateau for mainsequence stars. This suggests that chromospheric activity in the T Tauri stars falls to the levels of the older stars by a separate decay scheme. The decline in pre-mainsequence activity may be caused by the evolutionary shallowing of the convection zone, while on the main-sequence it is due to the star's spindown. This hypothesis needs confirmation, but relatively few T Tauri stars have been observed by IUE. Since the majority of the T Tauri stars thus far observed are probably more massive than the Sun, it may be inappropriate to compare their UV emission with that of the older I Mo dwarf stars. We propose here to observe the ultraviolet chromospheric and TR lines of pre-main-sequence stars we believe to be of ~1 M(sun). We have chosen a sample of low-luminosity M-type T Tauri stars from the T-associations in Lupus; if evolutionary tracks have any validity, a large fraction of those stars should be close to 1 M(sun)in mass. In order to place the stars more accurately on the H-R diagram and to determine their rotation rates (for comparison with the mainsequence stars), we plan concurrent visual spectroscopy and visual-infrared photometry.

  11. Advanced reflector materials for solar concentrators

    SciTech Connect

    Jorgensen, G; Williams, T; Wendelin, T

    1994-10-01

    This paper describes the research and development program at the U.S. National Renewable Energy Laboratory (NREL) in advanced reflector materials for solar concentrators. NREL's research thrust is to develop solar reflector materials that maintain high specular reflectance for extended lifetimes under outdoor service conditions and whose cost is significantly lower than existing products. Much of this work has been in collaboration with private-sector companies that have extensive expertise in vacuum-coating and polymer-film technologies. Significant progress and other promising developments will be discussed. These are expected to lead to additional improvements needed to commercialize solar thermal concentration systems and make them economically attractive to the solar manufacturing industry. To explicitly demonstrate the optical durability of candidate reflector materials in real-world service conditions, a network of instrumented outdoor exposure sites has been activated.

  12. Advanced reflector materials for solar concentrators

    NASA Astrophysics Data System (ADS)

    Jorgensen, Gary; Williams, Tom; Wendelin, Tim

    1994-10-01

    This paper describes the research and development at the US National Renewable Energy Laboratory (NREL) in advanced reflector materials for solar concentrators. NREL's research thrust is to develop solar reflector materials that maintain high specular reflectance for extended lifetimes under outdoor service conditions and whose cost is significantly lower than existing products. Much of this work has been in collaboration with private-sector companies that have extensive expertise in vacuum-coating and polymer-film technologies. Significant progress and other promising developments will be discussed. These are expected to lead to additional improvements needed to commercialize solar thermal concentration systems and make them economically attractive to the solar manufacturing industry. To explicitly demonstrate the optical durability of candidate reflector materials in real-world service conditions, a network of instrumented outdoor exposure sites has been activated.

  13. Secondary pattern computation of an offset reflector antenna

    NASA Technical Reports Server (NTRS)

    Acosta, R. J.

    1985-01-01

    Reflector antennas are widely used in communications satellite systems because they provide high gain at low cost. In analyzing reflector antennas the computation of the secondary pattern is the main concern. A computer program for calculating the secondary pattern of an offset reflector has been developed and implemented at the NASA Lewis Research Center. The theoretical foundation for this program is based on the use of geometrical optics to describe the fields from the feed to the reflector surface and to the aperture plane. The resulting aperture field distribution is then transformed to the far-field zone by the fast Fourier transform algorithm. Comparing this technique with other well-known techniques (the geometrical theory of diffraction, physical optics (Jacobi-Bessel), etc.) shows good agreement for large (diameter of 100 lambda or greater) reflector antennas.

  14. Adaptive forecasting of aftershock activity after the main shock

    NASA Astrophysics Data System (ADS)

    Omi, Takahiro; Ogata, Yosihiko; Hirata, Yoshito; Aihara, Kazuyuki

    2014-05-01

    Forecasting aftershock activity is useful to reduce seismic risks in the affected area after the main shock. The difficulties to forecast aftershocks are (i) a forecasting model should be tailored to each aftershock sequence because the statistical property varies greatly according to an individual aftershock sequence and (ii) the forecasting model has to be estimated from highly deficient data where a significant fraction of early small aftershocks are missing from seismic records. To overcome this difficulty, we have been developing a statistical model to deal with incompletely detected aftershocks, in which the detection rate of aftershocks is sequentially estimated in a state-space modeling approach. Our method enables us to robustly estimate the forecasting model of underlying aftershocks including not only observed aftershocks but also missing ones from the incomplete catalog. We show that the Omori-Utsu formula can be well estimated only from a few hours of the data, and then it can be revised by the epidemic type aftershock sequence (ETAS) model to adaptively forecast an aftershock sequence with the individual cascading feature as the data size increases in real-time. We demonstrate that how these estimated models can effectively forecast the aftershock activity. We also discuss how these models can be implemented in an operational system for earthquake forecasting. References: T. Omi, Y. Ogata, Y. Hirata, and K. Aihiara, "Forecasting large aftershocks within one day after the main shock", Scientific Reports, 3, 2218 (2013). T. Omi, Y. Ogata, Y. Hirata, and K. Aihiara, "Estimating the ETAS model from an early aftershock sequence", (In submission).

  15. GaInAsP/silicon-on-insulator hybrid laser with ring-resonator-type reflector fabricated by N2 plasma-activated bonding

    NASA Astrophysics Data System (ADS)

    Hayashi, Yusuke; Suzuki, Junichi; Inoue, Satoshi; Tanvir Hasan, Shovon Muhammad; Kuno, Yuki; Itoh, Kazuto; Amemiya, Tomohiro; Nishiyama, Nobuhiko; Arai, Shigehisa

    2016-08-01

    III-V/Si hybrid integration with direct bonding is an attractive method of realizing an electrophotonic convergence router with a small size and a low power consumption. Plasma-activated bonding (PAB) is an effective approach for reducing thermal stress during the bonding process because PAB achieves a high bonding strength with low-temperature annealing. This time, the fabrication of a GaInAsP/silicon-on-insulator (SOI) hybrid laser with Si ring-resonator-type reflectors was demonstrated by N2 PAB. By measuring the lasing spectra, we confirmed the reflective characteristics resulting from the cascaded Si ring resonators. We also investigated kink characteristics, which occur around the threshold current, of the current-light output (I-L) characteristics, and successfully approximated the kink characteristics by considering saturable absorption occurring at the III-V/Si taper tip. The taper structure was investigated in terms of a passive device as well as an active device, and a structure for eliminating saturable absorption was proposed.

  16. Micromachined, Electrostatically Deformable Reflectors

    NASA Technical Reports Server (NTRS)

    Bartman, Randall K.; Wang, Paul K. C.; Miller, Linda M.; Kenny, Thomas W.; Kaiser, William J.; Hadaegh, Fred Y.; Agronin, Michael L.

    1995-01-01

    Micromachined, closed-loop, electrostatically actuated reflectors (microCLEARs) provide relatively simple and inexpensive alternatives to large, complex, expensive adaptive optics used to control wavefronts of beams of light in astronomy and in experimental laser weapons. Micromachining used to make deformable mirror, supporting structure, and actuation circuitry. Development of microCLEARs may not only overcome some of disadvantages and limitations of older adaptive optics but may also satisfy demands of potential market for small, inexpensive deformable mirrors in electronically controlled film cameras, video cameras, and other commercial optoelectronic instruments.

  17. Adaptive feed array compensation system for reflector antenna surface distortion

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Zaman, A.

    1989-01-01

    The feasibility of a closed loop adaptive feed array system for compensating reflector surface deformations has been investigated. The performance characteristics (gain, sidelobe level, pointing, etc.) of large communication antenna systems degrade as the reflector surface distorts mainly due to thermal effects from a varying solar flux. The compensating systems described in this report can be used to maintain the design performance characteristics independent of thermal effects on the reflector surface. The proposed compensating system employs the concept of conjugate field matching to adjust the feed array complex excitation coefficients.

  18. Large Deployable Reflector (LDR)

    NASA Technical Reports Server (NTRS)

    Alff, W. H.

    1980-01-01

    The feasibility and costs were determined for a 1 m to 30 m diameter ambient temperature, infrared to submillimeter orbiting astronomical telescope which is to be shuttle-deployed, free-flying, and have a 10 year orbital life. Baseline concepts, constraints on delivery and deployment, and the sunshield required are examined. Reflector concepts, the optical configuration, alignment and pointing, and materials are also discussed. Technology studies show that a 10 m to 30 m diameter system which is background and diffraction limited at 30 micron m is feasible within the stated time frame. A 10 m system is feasible with current mirror technology, while a 30 m system requires technology still in development.

  19. Incidental Reflector Comparison of Containerized Dry Fire Extinguishing Agents

    SciTech Connect

    Chapman, Bryan Scott; Wysong, Andrew Russell

    2016-12-14

    This document addresses the incidental reflector reactivity worth of containerized fire extinguishing agents authorized for use in PF-4 at Los Alamos National Laboratory (LANL). The intent of the document is to analyze dry fire extinguishing agent that remains in a container and is not actively being used in a fire emergency. The incidental reflector reactivity worth is determined by comparison to various thicknesses of close fitting water reflection which is commonly used to bound incidental reflectors in criticality safety evaluations. The conclusion is that even in unlimited quantities, when containerized the authorized dry fire extinguishing agents are bound by 0.4 inches of close fitting water.

  20. Wavefront Correction for Large, Flexible Antenna Reflector

    NASA Technical Reports Server (NTRS)

    Imbriale, William A.; Jammejad, Vahraz; Rajagopalan, Harish; Xu, Shenheng

    2010-01-01

    A wavefront-correction system has been proposed as part of an outer-space radio communication system that would include a large, somewhat flexible main reflector antenna, a smaller subreflector antenna, and a small array feed at the focal plane of these two reflector antennas. Part of the wavefront-correction system would reside in the subreflector, which would be a planar patch-element reflectarray antenna in which the phase shifts of the patch antenna elements would be controlled via microelectromechanical systems (MEMS) radio -frequency (RF) switches. The system would include the following sensing-and-computing subsystems: a) An optical photogrammetric subsystem built around two cameras would estimate geometric distortions of the main reflector; b) A second subsystem would estimate wavefront distortions from amplitudes and phases of signals received by the array feed elements; and c) A third subsystem, built around small probes on the subreflector plane, would estimate wavefront distortions from differences among phases of signals received by the probes. The distortion estimates from the three subsystems would be processed to generate control signals to be fed to the MEMS RF switches to correct for the distortions, thereby enabling collimation and aiming of the received or transmitted radio beam to the required precision.

  1. SEISMIC-REFLECTOR DATABASE SOFTWARE.

    USGS Publications Warehouse

    Wright, Evelyn L.; Hosom, John-Paul; ,

    1986-01-01

    The seismic data analysis (SDA) software system facilitates generation of marine seismic reflector databases composed of reflector depths, travel times, root-mean-square and interval velocities, geographic coordinates, and identifying information. System processes include digitizing of seismic profiles and velocity semblance curves, merging of velocity and navigation data with profile travel-time data, calculation of reflector depths in meters, profile and map graphic displays, data editing and smoothing, and entry of finalized data into a comprehensive database. An overview of concepts, file structures, and programs is presented.

  2. Activity-rotation relations for lower main sequence stars

    NASA Astrophysics Data System (ADS)

    Dobson-Hockey, Andrea Kay

    It was known for some time that stellar rotation and activity are related, both for chromospheric activity and control activity. Younger, more rapidly rotating stars of a given spectral type generally show higher levels of activity than do older, more slowly rotating stars. On the Sun acitivity is distinctly related to magnetic fields. This leads to the suggestion that activity, at least in solar-type stars, is traceable to a magnetic dynamo which results from the interaction of rotation and differential rotation with convection. The more efficient the coriolis forces are at introducing helicity into convective motions, the more the magnetic field will be amplified and the more activity that is expected. The precise nature of the relationship between magnetic fields, rotation, and activity remains to be well-defined. It is the purpose to examine the relationship between activity and rotation in order to better define and express such a relation (or relations). To meet this goal, a comprehensive sample of stars was collected from the published literature having two or more of the following: chromospheric Ca II, H, and K emission indices; coronal soft X-ray illumination; rotation rates; and where possible, ages. It is seen that the use of normalized activity units and Rossby number generally improves the correlation between activity and rotation. The use of the convective turnover time further permits a possible explanation for the distribution of stars in an activity-color diagram. A large and homogeneous data set permits better definition of previously examined functional dependencies such as the time decay of activity and the relationship between chromospheric and coronal activity indicators.

  3. Activity-rotation relations for lower main-sequence stars

    SciTech Connect

    Dobson-Hockey, A.K.

    1987-01-01

    It has been known for some time that stellar rotation and activity are related, both for chromospheric activity (e.g., Noyes et al. 1984) and coronal activity (e.g., Pallavicini et al. 1981; Maggio et al. 1987). Younger, more rapidly rotating stars of a given spectral type generally show higher levels of activity than do older, more slowly rotating stars. On the Sun, activity is distinctly related to magnetic fields. This leads to the suggestion that activity, at least in solar-type stars, is traceable to a magnetic dynamo which results from the interaction of rotation and differential rotation with convection. The more efficient the coriolis forces are at introducing helicity into convective motions, the more the magnetic field will be amplified and the more activity we may expect to see. The precise nature of the relationship between magnetic fields, rotation, and activity remains to be well-defined. This thesis examines the relationship between activity (both chromospheric and coronal) and rotation in order to better define and express such a relation (or relations).

  4. The Position and Attitude of Sub-reflector Modeling for TM65 m Radio Telescope

    NASA Astrophysics Data System (ADS)

    Sun, Z. X.; Chen, L.; Wang, J. Q.

    2016-01-01

    In the course of astronomical observations, with changes in angle of pitch, the large radio telescope will have different degrees of deformation in the sub-reflector support, back frame, main reflector etc, which will lead to the dramatic decline of antenna efficiency in both high and low elevation. A sub-reflector system of the Tian Ma 65 m radio telescope has been installed in order to compensate for the gravitational deformations of the sub-reflector support and the main reflector. The position and attitude of the sub-reflector are variable in order to improve the pointing performance and the efficiency at different elevations. In this paper, it is studied that the changes of position and attitude of the sub-reflector have influence on the efficiency of antenna in the X band and Ku band. A model has been constructed to determine the position and attitude of the sub-reflector with elevation, as well as the point compensation model, by observing the radio source. In addition, antenna efficiency was tested with sub-reflector position adjusted and fixed. The results show that the model of sub-reflector can effectively improve the efficiency of the 65 m radio telescope. In X band, the aperture efficiency of the radio telescope reaches more than 60% over the entire elevation range.

  5. Determinants of physical activity among Somali women living in Maine.

    PubMed

    Devlin, John T; Dhalac, Deqa; Suldan, Asha A; Jacobs, Ana; Guled, Khadija; Bankole, Kolawole A

    2012-04-01

    Somali women living in the US are at increased risk for chronic health conditions due to changes in lifestyle following immigration. Numerous barriers to physical activity have been reported in this population. Behavioral theory may inform the design of successful health interventions. We explored in focus groups the behavioral determinants of physical activity (theory of planned behavior, self-efficacy) among Somali women (N = 30). We found that most (two-thirds) subjects were sedentary, although women who had lived in the US for 10 years or longer were more likely to be active. Somali women recognize the health threat of physical inactivity, including high rates of obesity. Moral norms appear to be the major barrier to physical activity, due to prohibitions against exercising in public or in Western-style clothing. Taking moral norms into consideration should allow for the design of culturally-appropriate exercise programs that can address a major health threat in this vulnerable population.

  6. Reflectors for SAR performance testing.

    SciTech Connect

    Doerry, Armin Walter

    2008-01-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  7. Evolution of activity signatures during the main sequence phase

    NASA Astrophysics Data System (ADS)

    Skumanich, A.; MacGregor, K.

    Recent work on the decay of magnetic activity signatures, such as chromospheric/transition region/coronal emission as well as mean flare emission, with age for solar and later type stars is reviewed. In terms of magnetic flux, as measured by excess chromospheric Ca II luminosity, it is shown that a simple dynamo-rotation relation that incorporates both a saturated state with its characteristic critical rotation as well as an asymptotic linear power law, i.e., a scale free relation, fits the extant data that includes the dMe stars. Introducing the saturated dynamo state, as exemplified by the dMe stars, into activity power-power diagrams, allows for not only specification of the saturated state, but for definition of evolutionary tracks that represent the decay from the saturated state. Using the quiescent coronal X-ray power (luminosity) as a basic measure of magnetic activity, simple monomial relations for both the saturated state (linear) and for the evolutionary tracks governing both quiescent activity and mean flare activity are found. In particular, the coronal power loss is found to vary quadratically with the chromospheric power loss, hence with magnetic flux.

  8. Some patterns of woodcock activities on Maine summer fields

    USGS Publications Warehouse

    Krohn, W.B.

    1971-01-01

    Certain aspects of woodcock usage of summer fields were studied in Maine. Findings were as follows: ....1. On two study fields in 1968, numbers of woodcock first began spending nights in the fields during the second week of June. During 1968 and 1969, the number of birds flushed from the fields varied greatly between nights. Use of fields continued into the first week of November......2. Woodcock started flying into summer fields approximately 26 minutes after sunset. Unless disturbed, birds remained on fields throughout the night and started departing for diurnal covers about 48 minutes before sunrise. The duration of evening and morning flight periods averaged 13 to 15 minutes.....3. Woodcock did not necessarily use the same field throughout the summer. Five of the 36 birds taken as repeats were caught on fields other than where originally banded. However, it was believed that flights to and from fields were essentially local movements.....4. Vegetation appeared to have been a critical factor influencing the distribution of woodcock in fields. Areas of low ground cover interspersed with taller and denser cover were used most frequently.....5. Immatures, especially immature males, were the predominant age-sex class captured on Maine summer fields. The question of whether the age-sex composition of birds using summer fields is atypical of the total woodcock population requires additional study.

  9. The Main Sequence of Explosive Solar Active Regions: Comparison of Emerging and Mature Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, David; Moore, Ron

    2011-01-01

    For mature active regions, an active region s magnetic flux content determines the maximum free energy the active region can have. Most Large flares and CMEs occur in active regions that are near their free-energy limit. Active-region flare power radiated in the GOES 1-8 band increases steeply as the free-energy limit is approached. We infer that the free-energy limit is set by the rate of release of an active region s free magnetic energy by flares, CMEs and coronal heating balancing the maximum rate the Sun can put free energy into the active region s magnetic field. This balance of maximum power results in explosive active regions residing in a "mainsequence" in active-region (flux content, free energy content) phase space, which sequence is analogous to the main sequence of hydrogen-burning stars in (mass, luminosity) phase space.

  10. Design, Development and Testing of the GMI Reflector Deployment Assembly

    NASA Technical Reports Server (NTRS)

    Guy, Larry; Foster, Mike; McEachen, Mike; Pellicciotti, Joseph; Kubitschek, Michael

    2011-01-01

    The GMI Reflector Deployment Assembly (RDA) is an articulating structure that accurately positions and supports the main reflector of the Global Microwave Imager (GMI) throughout the 3 year mission life. The GMI instrument will fly on the core Global Precipitation Measurement (GPM) spacecraft and will be used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydrometeorological predictions through more accurate and frequent precipitation measurements1. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard to design, build, and test the GMI instrument. The RDA was designed and manufactured by ATK Aerospace Systems Group to meet a number of challenging packaging and performance requirements. ATK developed a flight-like engineering development unit (EDU) and two flight mechanisms that have been delivered to BATC. This paper will focus on driving GMI instrument system requirements, the RDA design, development, and test activities performed to demonstrate that requirements have been met.

  11. A Cassegrain reflector system for compact range applications

    NASA Technical Reports Server (NTRS)

    Rader, Mark D.; Burnside, Walter D.

    1986-01-01

    An integral part of a compact range is the means of providing a uniform plane wave. A Cassegrain reflector system is one alternative for achieving this goal. Theoretically, this system offers better performance than a simple reflector system. The longer pathlengths in the Cassegrain system lead to a more uniform field in the plane of interest. The addition of the subreflector creates several problems, though. System complexity is increased both in terms of construction and performance analysis. The subreflector also leads to aperture blockage and the orientation of the feed now results in spillover illuminating the target areas as well as the rest of the range. Finally, the addition of the subreflector leads to interaction between the two reflectors resulting in undesired field variations in the plane of interest. These difficulties are addressed and through the concept of blending the surfaces, a Cassegrain reflector system is developed that will provide a uniform plane wave that offers superior performance over large target areas for a given size reflector system. Design and analysis is implemented by considering the main reflector and subreflector separately. Then the system may be put together and the final design and system analysis completed.

  12. Reflector system for a lighting fixture

    DOEpatents

    Siminovitch, M.J.; Page, E.; Gould, C.T.

    1998-09-08

    Disclosed herein is a reflector system for a lighting fixture having a illumination source surrounded by an envelope. The reflector system includes a first reflector surrounding the illumination source. The reflector system also includes a second reflector which is non-contiguous with the first reflector and which surrounds the illumination source. The illumination source creates light rays which are reflected by the first and second reflectors. The first reflector directs light rays toward the center line of the fixture. However, the reflected rays despite being so reflected do not substantially intersect the envelope. The reflected light rays from the second reflector being directed so that they diverge from the center line of the fixture avoiding intersection with the semi-transparent envelope. 5 figs.

  13. Reflector system for a lighting fixture

    DOEpatents

    Siminovitch, Michael J.; Page, Erik; Gould, Carl T.

    2001-01-01

    Disclosed herein is a reflector system for a lighting fixture having a illumination source surrounded by an envelope. The reflector system includes a first reflector surrounding the illumination source. The reflector system also includes a second reflector which is non-contiguous with the first reflector and which surrounds the illumination source. The illumination source creates light rays which are reflected by the first and second reflectors. The first reflector directs light rays toward the center line of the fixture. However, the reflected rays despite being so reflected do not substantially intersect the envelope. The reflected light rays from the second reflector being directed so that they diverge from the center line of the fixture avoiding intersection with the semi-transparent envelope.

  14. Reflector system for a lighting fixture

    DOEpatents

    Siminovitch, Michael J.; Page, Erik; Gould, Carl T.

    1998-01-01

    Disclosed herein is a reflector system for a lighting fixture having a illumination source surrounded by an envelope. The reflector system includes a first reflector surrounding the illumination source. The reflector system also includes a second reflector which is non-contiguous with the first reflector and which surrounds the illumination source. The illumination source creates light rays which are reflected by the first and second reflectors. The first reflector directs light rays toward the center line of the fixture. However, the reflected rays despite being so reflected do not substantially intersect the envelope. The reflected light rays from the second reflector being directed so that they diverge from the center line of the fixture avoiding intersection with the semi-transparent envelope.

  15. Active magnetic suspension in main magnetic field of electric motor

    NASA Astrophysics Data System (ADS)

    Urusov, I. D.; Galkin, V. I.; Likhoshvay, I. P.

    1985-10-01

    An active magnetic suspension for the rotor of an electric motor is considered, especially in small or miniature high-speed devices such as gyros, microturbomachines, and machine-tool spindle drives where it would eliminate the need for extra bearings and contribute to size and weight reduction. A disk-type rotor made of a ferromagnetic material is located horizontally inside the bore of a vertical stator so that weight and external loads compensate the magnetic pull upward. This pull is generated by the magnetic field in the air gap and can be automatically controlled by an electronic feedback circuit which regulates the stator input voltage depending on the rotor position along the stator bore, with a displacement transducer on the rotor indicating the position. The performance of such a suspension with automatic control in a 3-phase induction motor is analyzed on the basis of the system of differential equations describing the behavior of the electromechanical system during axial oscillations of the rotor, assuming a constant rotor speed during the transient periods.

  16. Large deployable reflectors for telecom and earth observation applications

    NASA Astrophysics Data System (ADS)

    Scialino, L.; Ihle, A.; Migliorelli, M.; Gatti, N.; Datashvili, L.; van `t Klooster, K.; Santiago Prowald, J.

    2013-12-01

    Large deployable antennas are one of the key components for advanced missions in the fields of telecom and earth observation. In the recent past, missions have taken on board large deployable reflector (LDR) up to 22 m of diameter and several missions have already planned embarking large reflectors, such as the 12 m of INMARSAT XL or BIOMASS. At the moment, no European LDR providers are available and the market is dominated by Northrop-Grumman and Harris. Consequently, the development of European large reflector technology is considered a key step to maintain commercial and strategic competitiveness (ESA Large Reflector Antenna Working Group Final Report, TEC-EEA/2010.595/CM, 2010). In this scenario, the ESA General Study Project RESTEO (REflector Synergy between Telecom and Earth Observation), starting from the identification of future missions needs, has identified the most promising reflector concepts based on European heritage/technology, able to cover the largest range of potential future missions for both telecom and earth observation. This paper summarizes the activities and findings of the RESTEO Study.

  17. Solar Tracking Error Analysis of Fresnel Reflector

    PubMed Central

    Zheng, Jiantao; Yan, Junjie; Pei, Jie; Liu, Guanjie

    2014-01-01

    Depending on the rotational structure of Fresnel reflector, the rotation angle of the mirror was deduced under the eccentric condition. By analyzing the influence of the sun tracking rotation angle error caused by main factors, the change rule and extent of the influence were revealed. It is concluded that the tracking errors caused by the difference between the rotation axis and true north meridian, at noon, were maximum under certain conditions and reduced at morning and afternoon gradually. The tracking error caused by other deviations such as rotating eccentric, latitude, and solar altitude was positive at morning, negative at afternoon, and zero at a certain moment of noon. PMID:24895664

  18. Electromagnetic backscattering by corner reflectors

    NASA Technical Reports Server (NTRS)

    Balanis, C. A.; Griesser, T.

    1986-01-01

    The Geometrical Theory of Diffraction (GTD), which supplements Geometric Optics (GO), and the Physical Theory of Diffraction (PTD), which supplements Physical Optics (PO), are used to predict the backscatter cross sections of dihedral corner reflectors which have right, obtuse, or acute included angles. These theories allow individual backscattering mechanisms of the dihedral corner reflectors to be identified and provide good agreement with experimental results in the azimuthal plane. The advantages and disadvantages of the geometrical and physical theories are discussed in terms of their accuracy, usefulness, and complexity. Numerous comparisons of analytical results with experimental data are presented. While physical optics alone is more accurate and more useful than geometrical optics alone, the combination of geometrical optics and geometrical diffraction seems to out perform physical optics and physical diffraction when compared with experimental data, especially for acute angle dihedral corner reflectors.

  19. Lamp bulb with integral reflector

    DOEpatents

    Levin, Izrail; Shanks, Bruce; Sumner, Thomas L.

    2001-01-01

    An improved electrodeless discharge lamp bulb includes an integral ceramic reflector as a portion of the bulb envelope. The bulb envelope further includes two pieces, a reflector portion or segment is cast quartz ceramic and a light transmissive portion is a clear fused silica. In one embodiment, the cast quartz ceramic segment includes heat sink fins or stubs providing an increased outside surface area to dissipate internal heat. In another embodiment, the quartz ceramic segment includes an outside surface fused to eliminate gas permeation by polishing.

  20. Extreme Precision Antenna Reflector Study Results

    NASA Technical Reports Server (NTRS)

    Sharp, G. R.; Gilger, L. D.; Ard, K. E.

    1985-01-01

    Thermal and mechanical distortion degrade the RF performance of antennas. The complexity of future communications antennas requires accurate, dimensionally stable antenna reflectors and structures built from materials other than those currently used. The advantages and disadvantages of using carbon fibers in an epoxy matrix are reviewed as well as current reflector fabrications technology and adjustment. The manufacturing sequence and coefficient of thermal expansion of carbon fiber/borosilicate glass composites is described. The construction of a parabolic reflector from this material and the assembling of both reflector and antenna are described. A 3M-aperture-diameter carbon/glass reflector that can be used as a subassembly for large reflectors is depicted. The deployment sequence for a 10.5M-aperture-diameter antenna, final reflector adjustment, and the deployment sequence for large reflectors are also illustrated.

  1. Adjusting the Contour of Reflector Panels

    NASA Technical Reports Server (NTRS)

    Palmer, W. B.; Giebler, M. M.

    1984-01-01

    Postfabrication adjustment of contour of panels for reflector, such as parabolic reflector for radio antennas, possible with simple mechanism consisting of threaded stud, two nuts, and flexure. Contours adjusted manually.

  2. Large space-borne reflector antenna characterization: Evaluation and distortion compensation

    NASA Astrophysics Data System (ADS)

    Hoferer, Robert Alois

    For space-borne reflector antenna applications, both size and weight of the antenna is restricted to the payload capacity of the launch vehicle. Advantages in the material and manufacturing capabilities of large reflector antennas over the recent years have made it possible to propose antenna systems with ever increasing size and operating frequency. Before deployment, however, it is crucial to accurately evaluate the radiation characteristics of these antennas. Also, if compensatory measures are applied to compensate for structural distortions, it is necessary to assess its effectiveness for a particular the examined antenna configuration. In this dissertation, an effective dual reflector analysis technique has been developed, using a combination of Physical Optics, Geometrical Optics and Fourier-Jacobi surface expansion. This analysis technique has been applied to two classes of reflector antenna applications. First, two challenging single reflector antenna configurations have been designed and analyzed. Second, the analysis technique is used for subreflector shaping in the process of main reflector distortion compensation for an electrically large dual reflector antenna configuration. Note that the inflatable reflector antenna configurations investigated in this thesis belong to the class reflector antennas larger than 20 m, which are now being considered for future space missions.

  3. KuDGR- Dual Gridded Carbon Fiber Reinforced Plastic Reflector

    NASA Astrophysics Data System (ADS)

    Ihle, Alexander; Reichmann, O.; Lori, M.; Nathrath, N.; Pereira, C.; Linke, S.; Rinous, P.

    2014-06-01

    In the frame of an ESA-funded TRP activity HPS GmbH, together with INVENT GmbH and INEGI, has developed an advanced concept for dual gridded reflectors. The target frequency band is the Ku-band requiring high in-orbit thermo-elastic stability. It is a follow-on of the previous KaDGR [1] activity. The concept concerns the polarisation grid of the front and rear reflector. The grids are connected by a full CFRP monolithic peripheral ring. The demonstrator has an overall diameter of 1.4 x 1.2 m and a weight of only 4.23 kg. The design of this concept allows for smaller and larger reflectors.In the following we will present the results of the different development steps and current status of the TRP activity.

  4. Ellipsoidal reflectors in biomedical diagnostic

    NASA Astrophysics Data System (ADS)

    Bezuglyi, M. A.; Bezuglaya, N. V.

    2013-11-01

    In this work were considered photometric tools for biomedical diagnostics, which contain a mirror ellipsoid of revolution. Proposed schemes with ellipsoidal reflectors for diagnostics in reflected and in reflected and transmitted light. A comparative analysis of measurement standards scattering surfaces was held.

  5. Membrane Shell Reflector Segment Antenna

    NASA Technical Reports Server (NTRS)

    Fang, Houfei; Im, Eastwood; Lin, John; Moore, James

    2012-01-01

    The mesh reflector is the only type of large, in-space deployable antenna that has successfully flown in space. However, state-of-the-art large deployable mesh antenna systems are RF-frequency-limited by both global shape accuracy and local surface quality. The limitations of mesh reflectors stem from two factors. First, at higher frequencies, the porosity and surface roughness of the mesh results in loss and scattering of the signal. Second, the mesh material does not have any bending stiffness and thus cannot be formed into true parabolic (or other desired) shapes. To advance the deployable reflector technology at high RF frequencies from the current state-of-the-art, significant improvements need to be made in three major aspects: a high-stability and highprecision deployable truss; a continuously curved RF reflecting surface (the function of the surface as well as its first derivative are both continuous); and the RF reflecting surface should be made of a continuous material. To meet these three requirements, the Membrane Shell Reflector Segment (MSRS) antenna was developed.

  6. Polarization losses in reflector antennas

    NASA Astrophysics Data System (ADS)

    Safak, M.; Yazgan, E.

    1985-08-01

    Various definitions for polarization-loss efficiency of Cassegrainian and front-fed reflectors are compared. The effects of flare angle, feed taper and the feed pattern asymmetry on the polarization-loss efficiency are investigated. The definitions based on aperture fields are shown to be inadequate and far fields must be used for calculating the polarization losses.

  7. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings...

  8. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings...

  9. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings...

  10. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings...

  11. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Radar reflector. 169.726 Section 169.726 Shipping COAST... Control, Miscellaneous Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design while underway. Markings...

  12. Primary reflector for solar energy collection systems

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor); Stephens, J. B.

    1978-01-01

    A fixed, linear, ground-based primary reflector is disclosed which has an extended curved sawtooth-contoured surface covered with a metalized polymeric reflecting material. The device reflects solar energy to a movably supported collector that is kept at the concentrated line focus of the reflector primary. The primary reflector may be constructed by a process utilizing well-known freeway paving machinery.

  13. Power transient analyses of experimental in-reflector devices during safety shutdown in Jules Horowitz Reactor (JHR)

    SciTech Connect

    Camprini, P. C.; Sumini, M.; Artioli, C.; Gonnier, C.; Pouchin, B.; Bourdon, S.

    2012-07-01

    The Jules Horowitz Reactor (JHR) is designed to be a 100 MW material testing reactor (MTR) and it is expected to become the reference facility in the framework of European nuclear research activity. As the core neutron spectrum is quite fast, several experimental devices concerning fuel studies have been conceived to be placed in the reflector in order to exploit a proper thermal neutron flux irradiation. Since the core power is relatively high, the neutronic coupling between the reactor core and the reflector devices has to be taken into account for different rod insertions. In fact the thermal power produced within the fuel samples is considerable. Heat removal during shutdown is a main topic in nuclear safety and it is worth to analyse thermal power transients in fuel samples as well. Here a thermal hydraulic model for JHR core is proposed aiming at a simple and representative description as far as reactivity feedbacks are concerned. Then it is coupled with a neutronic pointwise kinetics analysis by means of the DULCINEE code to compute core power transient calculations. Moreover, some reflector-core coupling evaluations are performed through Monte Carlo method using the TRIPOLI 4.7 code. The JHR equilibrium cycle is considered with respect to four fuel compositions namely Beginning of Cycle (BOC), Xenon Saturation Point (XSP), Middle of Cycle (MOC) and End of Cycle (EOC). Then thermal power transients in the experimental reflector devices are evaluated during safety shutdowns and they are verified for all these cycle steps. (authors)

  14. The design of the central-axis reflector (ZAS).

    NASA Astrophysics Data System (ADS)

    Hügenell, H.

    1988-10-01

    The central-axis reflector (ZAS), the design principle which is presented in the paper is a segmented-mirror telescope. The inventions relate mainly to the optical system and to the tracking apparatus. A large number of small individual mirror bodies, ground off-axis (hexagonal/polygonal) produce one primary mirror with closed circular aperture when joined together.

  15. Improving the Efficiency of Quasi-Optical Bragg Reflectors

    NASA Astrophysics Data System (ADS)

    Khozin, M. A.; Denisov, G. G.; Belousov, V. I.

    2017-01-01

    In the analysis of propagation of wave beams in quasi-optical transmission lines, the loss rate and transformation of modes by various elements of the transmission line are of great importance. The effects occurring when a spatially bounded, obliquely incident wave beam is reflected from a Bragg resonator being a periodic, plane-layered medium with varied dielectric permittivity are considered. Such a reflector can be used as a frequency-selective element of the transmission line. Since the reflection coefficient of a plane wave from the Bragg reflector depends on its incidence angle, there occurs a transformation of the reflected beam. Analytical expressions for the beam displacement, the angle of deflection of the beam from the mirror reflection direction, and the wavefront curvature variation have been obtained. The influence of the mentioned effects on characteristics of the reflected wave beam in the main band of the Bragg reflector is numerically analyzed. The possibility of compensation for these distortions is considered.

  16. Beam-Steerable Flat-Panel Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Lee, Choon Sae; Lee, Chanam; Miranda, Felix A.

    2005-01-01

    Many space applications require a high-gain antenna that can be easily deployable in space. Currently, the most common high-gain antenna for space-born applications is an umbrella-type reflector antenna that can be folded while being lifted to the Earth orbit. There have been a number of issues to be resolved for this type of antenna. The reflecting surface of a fine wire mesh has to be light in weight and flexible while opening up once in orbit. Also the mesh must be a good conductor at the operating frequency. In this paper, we propose a different type of high-gain antenna for easy space deployment. The proposed antenna is similar to reflector antennas except the curved main reflector is replaced by a flat reconfigurable surface for easy packing and deployment in space. Moreover it is possible to steer the beam without moving the entire antenna system.

  17. Computer-aided design of reflector antennas - The Green Bank Radio Telescope

    NASA Astrophysics Data System (ADS)

    Terada, Marco A. B.; Stutzman, Warren L.

    1998-03-01

    This paper presents an evaluation of the electrical performance of the Green Bank Telescope (GBT) reflector antenna, operating as single- and dual-offset configurations, as well as a general overview of the GBT system. The GBT dual-offset Gregorian configuration is designed for low cross polarization (XPOL) using the dual-offset reflector antenna (DORA) synthesis package code. The procedure implemented in DORA to upgrade an existing main reflector to a low cross-polarized dual-offset Gregorian reflector antenna is also described. All computed patterns were obtained with the parabolic reflector analysis code (PRAC) program, and with the commercial code GRASP7. The GBT radiation patterns and performance values indicate that low XPOL performance can be achieved with a dual-offset configuration, provided that a low XPOL feed is used. The GBT configuration is employed as a case example for the aforementioned procedure.

  18. Actuator Grouping Optimization on Flexible Space Reflectors

    NASA Technical Reports Server (NTRS)

    Hill, Jeffrey R.; Wang, K. W.; Fang, Houfei; Quijano, Ubaldo

    2011-01-01

    With the rapid advances in deployable membrane and mesh antenna technologies, the feasibility of developing large, lightweight reflectors has greatly improved. In order to achieve the required surface accuracy, precision surface control is needed on these lightweight reflectors. For this study, an analytical model is shown which combines a flexible Kapton reflector with Polyvinylidene fluoride (PVDF) actuators for surface control. Surface errors are introduced that are similar to real world scenarios, and a least squares control algorithm is developed for surface control. Experimental results on a 2.4 meter reflector show that while the analytical reflector model is generally correct, due to idiosyncrasies in the reflector it cannot be used for online control. A new method called the En Mass Elimination algorithm is used to determine the optimal grouping of actuators when the number of actuators in the system exceeds the number of power supplies available.

  19. Integrated 222-GHz corner-reflector antennas

    NASA Astrophysics Data System (ADS)

    Gearhart, Steven S.; Ling, Curtis C.; Rebeiz, Gabriel M.

    1991-01-01

    A high-gain monolithic millimeter-wave antenna has been designed, fabricated, and tested at 222 GHz. The structure consists of a traveling-wave antenna integrated on a 1.2-micron dielectric membrane and suspended in a longitudinal cavity etched in a silicon wafer. A new traveling-wave antenna design yields a wideband input impedance and a low cross-polarization component in the E- and quasi-H-plane patterns. A directivity of 17.7 dB and a main-beam efficiency of 88.5 percent are calculated from the 222-GHz pattern measurements. The integrated corner-reflector antenna is well suited for millimeter- and submillimeter-wave imaging applications in large f-number systems.

  20. Vibration suppression for Precision Segmented Reflector backup structure.

    NASA Astrophysics Data System (ADS)

    Chen, G. S.; Garba, J. A.; Wada, B. K.

    1989-09-01

    This paper describes an ongoing effort at the JPL on the vibration suppression for the Precision Segmented Reflector backup structure. The effort is centered on the vibration damping augmentation through a system consisting of active and passive damping members. An active member is a structural member with built-in piezoelectric actuator and sensors. A bridge feedback technique developed in the communication engineering is applied locally to the active member for active damping augmentation.

  1. Design concepts for large reflector antenna structures

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.; Adams, L. R.

    1983-01-01

    Practical approaches for establishing large, precise antenna reflectors in space are described. Reflector surfaces consisting of either solid panels or knitted mesh are considered. The approach using a deep articulated truss structure to support a mesh reflector is selected for detailed investigations. A new sequential deployment concept for the tetrahedral truss is explained. Good joint design is discussed, and examples are described both analytically and by means of demonstration models. The influence of curvature on the design and its vibration characteristics are investigated.

  2. Lamp with a truncated reflector cup

    DOEpatents

    Li, Ming; Allen, Steven C.; Bazydola, Sarah; Ghiu, Camil-Daniel

    2013-10-15

    A lamp assembly, and method for making same. The lamp assembly includes first and second truncated reflector cups. The lamp assembly also includes at least one base plate disposed between the first and second truncated reflector cups, and a light engine disposed on a top surface of the at least one base plate. The light engine is configured to emit light to be reflected by one of the first and second truncated reflector cups.

  3. State-of-the-art low-cost solar reflector materials

    SciTech Connect

    Kennedy, C; Jorgensen, G

    1994-11-01

    Solar thermal technologies generate power by concentrating sunlight with large mirrors. The National Renewable Energy Laboratory (NREL) is working with industrial partners to develop the optical reflector materials needed for the successful deployment of this technology. The reflector materials must be low in cost and maintain high specular reflectance for extended lifetimes in severe outdoor environments. Currently, the best candidate materials for solar mirrors are silver-coated low-iron glass and silvered polymer films. Polymer reflectors are lighter in weight, offer greater flexibility in system design, and have the potential for lower cost than glass mirrors. In parallel with collaborative activities, several innovative candidate reflector-material constructions were investigated at NREL. The low-cost material requirement necessitates manufacturing compatible with mass-production techniques. Future cooperative efforts with the web-coating industry offers the promise of exciting new alternative materials and the potential for dramatic cost savings in developing advanced solar reflector materials.

  4. Evaluation of Hardware and Procedures for Astronaut Assembly and Repair of Large Precision Reflectors

    NASA Technical Reports Server (NTRS)

    Lake, Mark S.; Heard, Walter L., Jr.; Watson, Judith J.; Collins, Timothy J.

    2000-01-01

    A detailed procedure is presented that enables astronauts in extravehicular activity (EVA) to efficiently assemble and repair large (i.e., greater than 10m-diameter) segmented reflectors, supported by a truss, for space-based optical or radio-frequency science instruments. The procedure, estimated timelines, and reflector hardware performance are verified in simulated 0-g (neutral buoyancy) assembly tests of a 14m-diameter, offset-focus, reflector test article. The test article includes a near-flight-quality, 315-member, doubly curved support truss and 7 mockup reflector panels (roughly 2m in diameter) representing a portion of the 37 total panels needed to fully populate the reflector. Data from the tests indicate that a flight version of the design (including all reflector panels) could be assembled in less than 5 hours - less than the 6 hours normally permitted for a single EVA. This assembly rate essentially matches pre-test predictions that were based on a vast amount of historical data on EVA assembly of structures produced by NASA Langley Research Center. Furthermore, procedures and a tool for the removal and replacement of a damaged reflector panel were evaluated, and it was shown that EVA repair of this type of reflector is feasible with the use of appropriate EVA crew aids.

  5. Electronic Compensation For Distortion Of Antenna Reflector

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Cockrell, C.R.; Staton, L. D.

    1995-01-01

    Proposed method of obtaining approximately desired radiation or reception pattern from antenna that includes reflector based on concept of superposition of electromagnetic fields generated by multiple feedhorns or feed antenna elements arrayed at various positions near reflector and excited at electronically adjustable magnitudes and phases. In intended application, reflector nominally paraboloidal, feed elements N feedhorns in hexagonal array, and method used to compensate for deviations of real reflector surface from nominal paraboloidal shape. Method and concept also applicable to electronic beam steering and electronic antenna compensation in other situations.

  6. Low Sidelobe Scanning Beams for Parabolic Reflectors,

    DTIC Science & Technology

    Parabolic antennas, *Sidelobes, *Electronic scanners, Parabolas, Far field, Antenna feeds , Reflectors, Low level, Amplitude, Distortion, Configurations, Secondary, Compensation, Feeding , Symposia, Taper

  7. Solar thermal collectors using planar reflector

    NASA Technical Reports Server (NTRS)

    Espy, P. N.

    1978-01-01

    Specular reflectors have been used successfully with flat-plate collectors to achieve exceptionally high operating temperatures and high delivered energy per unit collector area. Optimal orientation of collectors and reflectors can result in even higher performance with an improved relationship between energy demand and supply. This paper reports on a study providing first order optimization of collector-reflector arrays in which single- and multiple-faceted reflectors in fixed or singly adjustable configurations provide delivered energy maxima in either summer or winter.

  8. Passive solar reflector satellite revisited

    NASA Astrophysics Data System (ADS)

    Polk, C.; Daly, J. C.

    1980-07-01

    Passive light weight reflectors in space which direct the incident solar energy to a specified location on the Earth surface are proposed as an alternative system for the solar power satellite to overcome conversion losses and to avoid the need for photovoltaic cells. On Earth, either photovoltaic cells or a steam turbine alternator on a solar tower, or a similar conventional, relatively high efficiency cycle are used for electricity generation. The constraints which apply to the design of the optical system if a single satellite is placed in geostationary orbit are outlined. A single lens and a two lens system are discussed.

  9. Passive solar reflector satellite revisited

    NASA Technical Reports Server (NTRS)

    Polk, C.; Daly, J. C.

    1980-01-01

    Passive light weight reflectors in space which direct the incident solar energy to a specified location on the Earth surface are proposed as an alternative system for the solar power satellite to overcome conversion losses and to avoid the need for photovoltaic cells. On Earth, either photovoltaic cells or a steam turbine alternator on a solar tower, or a similar conventional, relatively high efficiency cycle are used for electricity generation. The constraints which apply to the design of the optical system if a single satellite is placed in geostationary orbit are outlined. A single lens and a two lens system are discussed.

  10. Conformal Membrane Reflectors for Deployable Optics

    NASA Technical Reports Server (NTRS)

    Hood, Patrick J.; Keys, Andrew S. (Technical Monitor)

    2002-01-01

    This presentation reports the Phase I results on NASA's Gossamer Spacecraft Exploratory Research and Technology Program. Cornerstone Research Group, Inc., the University of Rochester, and International Photonics Consultants collaborated to investigate the feasibility of free-standing, liquid-crystal-polymer (LCP) reflectors for integration into space-based optical systems. The goal of the program was to achieve large-diameter, broadband. reflective membranes that are resistant to the effects of space, specifically cryogenic environments and gamma-ray irradiation. Additionally, we assessed the applicability of utilizing the technology as tight sails, since, by their very nature, these films offer high-reflectivity at specified wavelengths. Previous research programs have demonstrated all-polymer, narrow-band Specular reflectors and diffuse membrane reflectors. The feasibility of fabricating an all-polymer broadband specular reflector and a narrow-band specular membrane reflector was assessed in the Phase I Gossamer program. In addition, preliminary gamma irradiation studies were conducted to determine the stability of the polymer reflectors to radiation. Materials and process technology were developed to fabricate coupon-scale reflectors of both broad- and narrow-band specular reflectors in Phase 1. This presentation will report the results of these studies, including, the performance of a narrow-band specular membrane. Gamma irradiation exposures indicate limited impact on the optical performance although additional exposure studies are warranted. Plans to scale up the membrane fabrication process will be presented.

  11. Back surface reflectors for solar cells

    NASA Technical Reports Server (NTRS)

    Chai, A. T.

    1980-01-01

    Sample solar cells were fabricated to study the effects of various back surface reflectors on the device performance. They are typical 50 micrometers thick, space quality, silicon solar cells except for variations of the back contact configuration. The back surfaces of the sample cells are polished to a mirror like finish, and have either conventional full contacts or grid finger contacts. Measurements and evaluation of various metallic back surface reflectors, as well as cells with total internal reflection, are presented. Results indicate that back surface reflectors formed using a grid finger back contact are more effective reflectors than cells with full back metallization and that Au, Ag, or Cu are better back surface reflector metals than Al.

  12. Nanolaminate Membranes as Cylindrical Telescope Reflectors

    NASA Technical Reports Server (NTRS)

    Dooley, Jennifer; Dragovan, Mark; Hickey, Gregory; Lih, Shyh-Shiu Lih

    2010-01-01

    A document discusses a proposal to use axially stretched metal nanolaminate membranes as lightweight parabolic cylindrical reflectors in the Dual Anamorphic Reflector Telescope (DART) - a planned spaceborne telescope in which the cylindrical reflectors would be arranged to obtain a point focus. The discussion brings together a combination of concepts reported separately in several prior NASA Tech Briefs articles, the most relevant being "Nanolaminate Mirrors With Integral Figure-Control Actuators" NPO -30221, Vol. 26, No. 5 (May 2002), page 90; and "Reflectors Made From Membranes Stretched Between Beams" NPO -30571, Vol. 33, No. 10 (October 2009), page 11a. The engineering issues receiving the greatest emphasis in the instant document are (1) the change in curvature associated with the Poisson contraction of a stretched nanolaminate reflector membrane and (2) the feasibility of using patches of poly(vinylidene fluoride) on the rear membrane surface as piezoelectric actuators to correct the surface figure for the effect of Poisson contraction and other shape errors.

  13. Piezocomposite Actuator Arrays for Correcting and Controlling Wavefront Error in Reflectors

    NASA Technical Reports Server (NTRS)

    Bradford, Samuel Case; Peterson, Lee D.; Ohara, Catherine M.; Shi, Fang; Agnes, Greg S.; Hoffman, Samuel M.; Wilkie, William Keats

    2012-01-01

    Three reflectors have been developed and tested to assess the performance of a distributed network of piezocomposite actuators for correcting thermal deformations and total wave-front error. The primary testbed article is an active composite reflector, composed of a spherically curved panel with a graphite face sheet and aluminum honeycomb core composite, and then augmented with a network of 90 distributed piezoelectric composite actuators. The piezoelectric actuator system may be used for correcting as-built residual shape errors, and for controlling low-order, thermally-induced quasi-static distortions of the panel. In this study, thermally-induced surface deformations of 1 to 5 microns were deliberately introduced onto the reflector, then measured using a speckle holography interferometer system. The reflector surface figure was subsequently corrected to a tolerance of 50 nm using the actuators embedded in the reflector's back face sheet. Two additional test articles were constructed: a borosilicate at window at 150 mm diameter with 18 actuators bonded to the back surface; and a direct metal laser sintered reflector with spherical curvature, 230 mm diameter, and 12 actuators bonded to the back surface. In the case of the glass reflector, absolute measurements were performed with an interferometer and the absolute surface was corrected. These test articles were evaluated to determine their absolute surface control capabilities, as well as to assess a multiphysics modeling effort developed under this program for the prediction of active reflector response. This paper will describe the design, construction, and testing of active reflector systems under thermal loads, and subsequent correction of surface shape via distributed peizeoelctric actuation.

  14. Aquarius Main Structure Configuration

    NASA Technical Reports Server (NTRS)

    Eremenko, Alexander

    2012-01-01

    The Aquarius/SAC-D Observatory is a joint US-Argentine mission to map the salinity at the ocean surface. This information is critical to improving our understanding of two major components of Earth's climate system - the water cycle and ocean circulation. By measuring ocean salinity from space, the Aquarius/SAC-D Mission will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Aquarius is the primary instrument on the SAC-D spacecraft. It consists of a Passive Microwave Radiometer to detect the surface emission that is used to obtain salinity and an Active Scatterometer to measure the ocean waves that affect the precision of the salinity measurement. The Aquarius Primary Structure houses instrument electronics, feed assemblies, and supports a deployable boom with a 2.5 m Reflector, and provides the structural interface to the SAC-D Spacecraft. The key challenge for the Aquarius main structure configuration is to satisfy the needs of component accommodations, ensuring that the instrument can meet all operational, pointing, environmental, and launch vehicle requirements. This paper describes the evolution of the Aquarius main structure configuration, the challenges of balancing the conflicting requirements, and the major configuration driving decisions and compromises.

  15. Solar-powered illuminated reflector

    SciTech Connect

    Roberts, J.C.

    1987-05-26

    A highway traffic marker is described comprising: a housing adapted to be secured to a highway; a reflector in the housing for reflecting light in at least one predetermined direction toward highway traffic; at least one light source in the housing; a battery in circuit with the light source; a photovoltaic system is the housing for charging the battery. The housing includes window means for transmitting light from the light source outward from the housing in the predetermined direction; and optical lightguide element is mounted in the housing for guiding light from the one light source to the window means. The optical lightguide element has a generally conical shape and the window means being a Fresnel lens.

  16. Integrated reflector antenna design and analysis

    NASA Technical Reports Server (NTRS)

    Zimmerman, M. L.; Lee, S. W.; Ni, S.; Christensen, M.; Wang, Y. M.

    1993-01-01

    Reflector antenna design is a mature field and most aspects were studied. However, of that most previous work is distinguished by the fact that it is narrow in scope, analyzing only a particular problem under certain conditions. Methods of analysis of this type are not useful for working on real-life problems since they can not handle the many and various types of perturbations of basic antenna design. The idea of an integrated design and analysis is proposed. By broadening the scope of the analysis, it becomes possible to deal with the intricacies attendant with modem reflector antenna design problems. The concept of integrated reflector antenna design is put forward. A number of electromagnetic problems related to reflector antenna design are investigated. Some of these show how tools for reflector antenna design are created. In particular, a method for estimating spillover loss for open-ended waveguide feeds is examined. The problem of calculating and optimizing beam efficiency (an important figure of merit in radiometry applications) is also solved. Other chapters deal with applications of this general analysis. The wide angle scan abilities of reflector antennas is examined and a design is proposed for the ATDRSS triband reflector antenna. The development of a general phased-array pattern computation program is discussed and how the concept of integrated design can be extended to other types of antennas is shown. The conclusions are contained in the final chapter.

  17. Conceptual Design of the Aluminum Reflector Antenna for DATE5

    NASA Astrophysics Data System (ADS)

    Qian, Yuan; Kan, Frank W.; Sarawit, Andrew T.; Lou, Zheng; Cheng, Jing-Quan; Wang, Hai-Ren; Zuo, Ying-Xi; Yang, Ji

    2016-08-01

    DATE5, a 5 m telescope for terahertz exploration, was proposed for acquiring observations at Dome A, Antarctica. In order to observe the terahertz spectrum, it is necessary to maintain high surface accuracy in the the antenna when it is exposed to Antarctic weather conditions. Structural analysis shows that both machined aluminum and carbon fiber reinforced plastic (CFRP) panels can meet surface accuracy requirements. In this paper, one design concept based on aluminum panels is introduced. This includes panel layout, details on panel support, design of a CFRP backup structure, and detailed finite element analysis. Modal, gravity and thermal analysis are all performed and surface deformations of the main reflector are evaluated for all load cases. At the end of the paper, the manufacture of a prototype panel is also described. Based on these results, we found that using smaller aluminum reflector panels has the potential to meet the surface requirements in the harsh Dome A environment.

  18. RPMA (Real Property Maintenance Activities) Consolidation Activities in the National Capital Region. Volume 1. Main Report.

    DTIC Science & Technology

    1984-05-01

    planning the activities of future IPCs. Pre-IPC Activities Participating installations should have been directed through command channels to take the...the task with minimal impact on the existing A workload, and (2) ensure that the request for inforniation is formal and sent through channels . Planners...34... . .•.....¢,.. -...... ,- % * .*. ...... ....... .°. •.-.-.-. •..... 39. The District init inttei the cofl ract Ior <I’MA t i i on;, e i, ( I i HQDA through command channels . 40

  19. Biological polarized light reflectors in stomatopod crustaceans

    NASA Astrophysics Data System (ADS)

    Chiou, Tsyr-Huei; Cronin, Thomas W.; Caldwell, Roy L.; Marshall, Justin

    2005-08-01

    Body parts that can reflect highly polarized light have been found in several species of stomatopod crustaceans (mantis shrimps). These polarized light reflectors can be grossly divided into two major types. The first type, usually red or pink in color to the human visual system, is located within an animal's cuticle. Reflectors of the second type, showing iridescent blue, are located beneath the exoskeleton and thus are unaffected by the molt cycle. We used reflection spectropolarimetry and transmission electron microscopy (TEM) to study the reflective properties and the structures that reflect highly polarized light in stomatopods. For the first type of reflector, the degree of polarization usually changes dramatically, from less than 20% to over 70%, with a change in viewing angle. TEM examination indicates that the polarization reflection is generated by multilayer thin-film interference. The second type of reflector, the blue colored ones, reflects highly polarized light to all viewing angles. However, these reflectors show a slight chromatic change with different viewing angles. TEM sections have revealed that streams of oval-shaped vesicles might be responsible for the production of the polarized light reflection. In all the reflectors we have examined so far, the reflected light is always maximally polarized at around 500 nm, which is close to the wavelength best transmitted by sea water. This suggests that the polarized light reflectors found in stomatopods are well adapted to the underwater environment. We also found that most reflectors produce polarized light with a horizontal e-vector. How these polarized light reflectors are used in stomatopod signaling remains unknown.

  20. New Horizons in C-F Activation by Main Group Electrophiles

    SciTech Connect

    Ozerov, Oleg V.

    2016-02-13

    This technical report describes progress on the DOE sponsored project "New Horizons in C-F Activation by Main Group Electrophiles" during the period of 09/15/2010 – 08/31/2015. The main goal of this project was to develop improved catalysts for conversion of carbon-fluorine bonds in potentially harmful compounds. The approach involved combining of a highly reactive positively charged main-group compound with a highly unreactive negatively charged species (anions) as a way to access potent catalysts for carbon-fluorine bond activation. This report details progress made in improving synthetic pathways to a variety of new anions with improved properties and analysis of their potential in catalysis.

  1. Distributed Bragg Reflectors With Reduced Optical Absorption

    DOEpatents

    Klem, John F.

    2005-08-16

    A new class of distributed Bragg reflectors has been developed. These distributed Bragg reflectors comprise interlayers positioned between sets of high-index and low-index quarter-wave plates. The presence of these interlayers is to reduce photon absorption resulting from spatially indirect photon-assisted electronic transitions between the high-index and low-index quarter wave plates. The distributed Bragg reflectors have applications for use in vertical-cavity surface-emitting lasers for use at 1.55 .mu.m and at other wavelengths of interest.

  2. Flat plate reflectors for PV collectors

    SciTech Connect

    Spielberg, J.I. )

    1989-01-01

    This article delineates experimentation establishing that fixed reflectors may be used with solar photovoltaic panels to obtain 70% of the efficiency of a dual-axis tracking system. Also described is how the power output of a stationary, non-tracking panel can be easily doubled via the addition of over-sized, overhanging wind reflectors in place of the traditional reflectors of a dual axis system. Discussion covers theory, experimental details, comparison of theory to results, and conclusions drawn. 15 refs., 7 figs., 1 tab.

  3. Rural Education for the Gifted: Activities at the University of Maine at Presque Isle.

    ERIC Educational Resources Information Center

    Anderson, Ruth B.

    Programs and courses about the gifted in rural areas have been offered by the University of Maine at Presque Isle since 1973. Activities (such as designing and building rockets, play writing and producing, and park design) and workshops have been held for and about the gifted. One of the problems with programs for this population is that they are…

  4. Polarization properties of reflector antennas used as radio telescopes

    NASA Astrophysics Data System (ADS)

    Ng, T.; Landecker, T. L.; Cazzolato, F.; Routledge, D.; Gray, A. D.; Reid, R. I.; Veidt, B. G.

    2005-10-01

    The distribution of cross polarization across the main beam and near sidelobes of a reflector antenna is calculated. Results are expressed in terms relevant to imaging in radio astronomy, using Stokes parameters, as plots of instrumental polarization Q/I, U/I, and V/I, showing conversion of total intensity of a signal which is unpolarized into apparent linear and circular polarization. The calculations use GRASP8, software that is based on physical optics and the physical theory of diffraction. For purposes of calculation, the symmetrical paraboloidal reflector (diameter ~40 wavelengths) is fed at the prime focus with a linearly polarized signal. Computed radiation patterns at a number of feed orientations are averaged to establish the antenna response to an unpolarized radio astronomy signal. The results of the computations are consistent with measurements of instrumental polarization of the Dominion Radio Astrophysical Observatory Synthesis Telescope at 1420 MHz made using unpolarized radio sources. For this telescope, the dominant source of instrumental polarization across the field is the cross polarization of the feed. The next most significant effect is scattering by the feed struts; both three-strut and four-strut configurations are examined. Struts affect performance in linear polarization but also introduce some instrumental circular polarization. The contribution to instrumental polarization from the reflector itself is comparatively small. Roughness of the reflector surface has relatively little effect in the main beam in Q and U but introduces V and also randomizes the polarization of the sidelobes. In all cases considered, the computations show that the first and subsequent sidelobes are highly polarized, with levels of instrumental polarization up to 50%.

  5. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.

    1992-01-01

    Virginia Tech has several articles which support the NASA Langley effort in the area of large aperture radiometric antenna systems. This semi-annual report reports on the following activities: a feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas and the design of array feeds for large reflector antennas.

  6. Analysis of a generalized dual reflector antenna system using physical optics

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Lagin, Alan R.

    1992-01-01

    Reflector antennas are widely used in communication satellite systems because they provide high gain at low cost. Offset-fed single paraboloids and dual reflector offset Cassegrain and Gregorian antennas with multiple focal region feeds provide a simple, blockage-free means of forming multiple, shaped, and isolated beams with low sidelobes. Such antennas are applicable to communications satellite frequency reuse systems and earth stations requiring access to several satellites. While the single offset paraboloid has been the most extensively used configuration for the satellite multiple-beam antenna, the trend toward large apertures requiring minimum scanned beam degradation over the field of view 18 degrees for full earth coverage from geostationary orbit may lead to impractically long focal length and large feed arrays. Dual reflector antennas offer packaging advantages and more degrees of design freedom to improve beam scanning and cross-polarization properties. The Cassegrain and Gregorian antennas are the most commonly used dual reflector antennas. A computer program for calculating the secondary pattern and directivity of a generalized dual reflector antenna system was developed and implemented at LeRC. The theoretical foundation for this program is based on the use of physical optics methodology for describing the induced currents on the sub-reflector and main reflector. The resulting induced currents on the main reflector are integrated to obtain the antenna far-zone electric fields. The computer program is verified with other physical optics programs and with measured antenna patterns. The comparison shows good agreement in far-field sidelobe reproduction and directivity.

  7. Trek across Maine 25th anniversary: a public health strategy to increase physical activity.

    PubMed

    Martin, Sarah Levin; Martin, Maurice; Perry, Tess; Harris, Jessica Maureen

    2013-09-01

    Could an annual event be an effective strategy to improve physical activity? Based on 25 years of data, we argue that it could be. Although there are eight recommended strategies to promote physical activity in the Community Guide, there is insufficient evidence for six others. Qualitative data collected from Trek Across Maine participants and other cause-specific events suggests that goal setting (i.e., individually adapted health behavior change) and family-based social support may be key factors in helping individuals become more physically active.

  8. 49 CFR 393.26 - Requirements for reflectors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... reflectors. (a) Mounting. Reflex reflectors shall be mounted at the locations required by § 393.11. In the... mounting height range. All permanent reflex reflectors shall be securely mounted on a rigid part of the... required to be permanently mounted to a part of the vehicle. Temporary reflex reflectors on...

  9. 49 CFR 393.26 - Requirements for reflectors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... reflectors. (a) Mounting. Reflex reflectors shall be mounted at the locations required by § 393.11. In the... mounting height range. All permanent reflex reflectors shall be securely mounted on a rigid part of the... required to be permanently mounted to a part of the vehicle. Temporary reflex reflectors on...

  10. 49 CFR 393.26 - Requirements for reflectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reflectors. (a) Mounting. Reflex reflectors shall be mounted at the locations required by § 393.11. In the... mounting height range. All permanent reflex reflectors shall be securely mounted on a rigid part of the... required to be permanently mounted to a part of the vehicle. Temporary reflex reflectors on...

  11. 49 CFR 393.26 - Requirements for reflectors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... reflectors. (a) Mounting. Reflex reflectors shall be mounted at the locations required by § 393.11. In the... mounting height range. All permanent reflex reflectors shall be securely mounted on a rigid part of the... required to be permanently mounted to a part of the vehicle. Temporary reflex reflectors on...

  12. 49 CFR 393.26 - Requirements for reflectors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... reflectors. (a) Mounting. Reflex reflectors shall be mounted at the locations required by § 393.11. In the... mounting height range. All permanent reflex reflectors shall be securely mounted on a rigid part of the... required to be permanently mounted to a part of the vehicle. Temporary reflex reflectors on...

  13. Focal region fields of distorted reflectors

    NASA Technical Reports Server (NTRS)

    Buris, N. E.; Kauffman, J. F.

    1988-01-01

    The problem of the focal region fields scattered by an arbitrary surface reflector under uniform plane wave illumination is solved. The physical optics (PO) approximation is used to calculate the current induced on the reflector. The surface of the reflector is described by a number of triangular domain-wise 5th degree bivariate polynomials. A 2-dimensional Gaussian quadrature is employed to numerically evaluate the integral expressions of the scattered fields. No Freshnel or Fraunhofer zone approximations are made. The relation of the focal fields problem to surface compensation techniques and other applications are mentioned. Several examples of distorted parabolic reflectors are presented. The computer code developed is included, together with instructions on its usage.

  14. Ellipsoidal optical reflectors reproduced by electroforming

    NASA Technical Reports Server (NTRS)

    Hungerford, W. J.; Larmer, J. W.; Levinsohn, M.

    1964-01-01

    An accurately dimensioned convex ellipsoidal surface, which will become a master after polishing, is fabricated from 316L stainless steel. When polishing of the master is completed, it is suspended in a modified watt bath for electroforming of nickel reflectors.

  15. Pactruss support structure for precision segmented reflectors

    NASA Technical Reports Server (NTRS)

    Hedgepeth, John M.

    1989-01-01

    The application of the Pactruss deployable structure to the support of large paraboloidal reflectors of very high precision was studied. The Pactruss concept, originally conceived for the Space Station truss, is shown to be suitable for use in a triangular arrangement to support a reflector surface composed of hexagonal reflector panels. A hybrid of Pactruss structural and deployable single-fold beams is shown to accommodate a center body. A minor alteration in the geometry is in order to avoid lockup during deployment. To assess the capability of the hybrid Pactruss structure, an example truss supporting a full-scale (20 meter diameter) infrared telescope was analyzed for static and dynamic performance. A truss structure weighing 800 kilograms gave adequate support to a reflector surface weighing 3,000 kilograms.

  16. The Design Of The Central-Axis Reflector (ZAS)

    NASA Astrophysics Data System (ADS)

    Hugenell, Hermann

    1990-07-01

    The central-axis reflector (LAS) , the design principle which is pre-sented below is a segmented-mirror telescope.The inventions relate main-ly to the optical system and to the tracking apparatus. A large number of small individual mirror bodies , ground off-axis (hexagonal/polygonal) produce one primary mirror with closed circular aperture when joined together. The overall design of the tracking apparatus results directly-and thus without unnecessary adornment- from the two planes of motion which have been reduced to a minimum but which are required for tracking of the telescope.

  17. Semiconductor Laser With Multilayer Dielectric Reflector

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1991-01-01

    Multilayer dielectric reflector included in proposed surface-emitting, distributed-feedback, grating semiconductor laser (e.g., a GaAlAs device). Contributes to efficiency and output power of laser by reducing amount of light entering substrate, where wasted by absorption. Index of refraction in reflector sublayers alternates between higher and lower value. Higher value less than effective index of refraction of waveguide layer.

  18. Design concepts for large antenna reflectors

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.

    1981-01-01

    A type of antenna reflector was studied in which a stiff structure is constructed to hold a membrane like reflector mesh in the correct position. An important basic restriction is that the mesh be controlled only by the structure and that no additional local shaping be employed. Furthermore, attention is confined to structures in which no adjustments would be made on assembly. Primary attention is given to the tetrahedral truss configuration because of its outstanding stiffness and dimensional stability.

  19. Aberrations of ellipsoidal reflectors for unit magnification.

    PubMed

    Mielenz, K D

    1974-12-01

    Ellipsoidal reflectors are useful for the 1:1 imaging of small objects without spherical and chromatic aberration. The magnitude of the off-axis aberrations of such reflectors is computed by application of Fermat's principle to the Hamiltonian point characteristic. The limiting form of the mirror aperture for which these aberrations do not exceed a set tolerance is an ellipse whose semiaxes depend on object size and angle of incidence.

  20. Solar central receiver heliostat reflector assembly

    DOEpatents

    Horton, Richard H.; Zdeb, John J.

    1980-01-01

    A heliostat reflector assembly for a solar central receiver system comprises a light-weight, readily assemblable frame which supports a sheet of stretchable reflective material and includes mechanism for selectively applying tension to and positioning the sheet to stretch it to optical flatness. The frame is mounted on and supported by a pipe pedestal assembly that, in turn, is installed in the ground. The frame is controllably driven in a predetermined way by a light-weight drive system so as to be angularly adjustable in both elevation and azimuth to track the sun and efficiently continuously reflect the sun's rays to a focal zone, i.e. central receiver, which forms part of a solar energy utilization system, such as a solar energy fueled electrical power generation system. The frame may include a built-in system for testing for optical flatness of the reflector. The preferable geometric configuration of the reflector is octagonal; however, it may be other shapes, such as hexagonal, pentagonal or square. Several different embodiments of means for tensioning and positioning the reflector to achieve optical flatness are disclosed. The reflector assembly is based on the stretch frame concept which provides an extremely light-weight, simple, low-cost reflector assembly that may be driven for positioning and tracking by a light-weight, inexpensive drive system.

  1. Solar central receiver heliostat reflector assembly

    SciTech Connect

    Horton, R.H.; Zdeb, J.J.

    1980-06-24

    A heliostat reflector assembly for a solar central receiver system comprises a light-weight, readily assemblable frame which supports a sheet of stretchable reflective material and includes a mechanism for selectively applying tension to and positioning the sheet to stretch it to optical flatness. The frame is mounted on and supported by a pipe pedestal assembly that, in turn, is installed in the ground. The frame is controllably driven in a predetermined way by a light-weight drive system so as to be angularly adjustable in both elevation and azimuth to track the sun and efficiently continuously reflect the sun's rays to a focal zone, i.e. central receiver, which forms part of a solar energy utilization system, such as a solar energy fueled electrical power generation system. The frame may include a built-in system for testing for optical flatness of the reflector. The preferable geometric configuration of the reflector is octagonal; however, it may be other shapes, such as hexagonal, pentagonal or square. Several different embodiments of means for tensioning and positioning the reflector to achieve optical flatness are disclosed. The reflector assembly is based on the stretch frame concept which provides an extremely light-weight, simple, low-cost reflector assembly that may be driven for positioning and tracking by a light-weight, inexpensive drive system. 14 figs.

  2. Solar central receiver heliostat reflector assembly

    SciTech Connect

    Horton, R.H.; Zdeb, J.J.

    1980-06-24

    A heliostat reflector assembly for a solar central receiver system comprises a light-weight, readily assemblable frame which supports a sheet of stretchable reflective material and includes mechanism for selectively applying tension to and positioning the sheet to stretch it to optical flatness. The frame is mounted on and supported by a pipe pedestal assembly that, in turn, is installed in the ground. The frame is controllably driven in a predetermined way by a light-weight drive system so as to be angularly adjustable in both elevation and azimuth to track the sun and efficiently continuously reflect the sun's rays to a focal zone, i.e., central receiver, which forms part of a solar energy utilization system, such as a solar energy fueled electrical power generation system. The frame may include a built-in system for testing for optical flatness of the reflector. The preferable geometric configuration of the reflector is octagonal; however, it may be other shapes, such as hexagonal, pentagonal or square. Several different embodiments of means for tensioning and positioning the reflector to achieve optical flatness are disclosed. The reflector assembly is based on the stretch frame concept which provides an extremely light-weight, simple, low-cost reflector assembly that may be driven for positioning and tracking by a light-weight, inexpensive drive system. 14 claims.

  3. Intestinal bacteria activate estrogenic effect of main constituents puerarin and daidzin of Pueraria thunbergiana.

    PubMed

    Park, Eun-Kyung; Shin, Jieun; Bae, Eun-Ah; Lee, Young-Chul; Kim, Dong-Hyun

    2006-12-01

    To understand the relationship between the metabolites and estrogenic activity of the main isoflavones puerarin and daidzin of the rhizome of Pueraria thunbergiana (PT, family Leguminosae), PT and its isoflavones were transformed by human intestinal bacteria and their estrogenic effects were investigated. All human fecal specimens hydrolyzed puerarin and daidzin to daidzein, but their hydrolyzing activities varied depending on the individuals. All intestinal bacteria isolated from human also hydrolyzed daidzin to daidzein, but a few bacteria transformed puerarin to daidzein. When the estrogenic effect of PT, puerarin and daidzin was compared with those of their metabolites, the metabolites more potently increased proliferation of MCF-7 cells than PT, puerarin and daidzin. The metabolite daidzein also potently increased estrogen-response c-fos mRNA and PR protein expressions. These findings suggest that intestinal bacteria, which can hydrolyze puerarin and/or daidzin, may activate a potent estrogenic activity of PT.

  4. Evaluation of Cellular Antioxidant and Antiproliferative Activities of Five Main Phyllanthus Emblica L. Cultivars in China.

    PubMed

    Li, Y; Sun, H Y; Yu, X Y; Liu, D; Wan, H X

    2015-01-01

    The cell-based antioxidant activity assay as more biological relevant assay was considered to be more accurate to predict antioxidant activity in vivo than chemical activity assays. In the present study, the five main Phyllanthus emblica L. cultivars in China were subjected for cellular antioxidant activity based on HepG2 cells as well as antiproliferative activity. Total phenolics, total flavonoids and oxygen radical absorbance capacity were also measured. The results showed that Qingyougan, Binggan and Boligan (832±100, 774±52 and 704±28 μmol of quercetin equivalents/100 g) had higher cellular antioxidant activity than Tianyougan and Yougan (553±50 and 457±24 μmol of quercetin equivalents/100 g) in phosphate buffered saline wash protocol whereas, Boligan (3735±217 μmol of quercetin equivalents/100 g) had the highest cellular antioxidant activity and Tianyougan (2025±171 μmol of quercetin equivalents/100 g) had the lowest cellular antioxidant activity in no phosphate buffered saline wash protocol. The highest and lowest antiproliferative activities were observed in Binggan and Tianyougan (median effective dose: 6.95±0.11 and 14.03±0.10 mg/ml), respectively. The significant correlation was only observed between total flavonoids and cellular antioxidant activity from no phosphate buffered saline wash protocol (R(2) =0.908, P<0.05), and total flavonoids and antiproliferative activity (R(2) =0.887, P<0.05), suggesting the major contribution of flavonoids to the bioactivities of emblica. Overall, the data obtained revealed that different Phyllanthus emblica L. cultivars had strong cellular antioxidant and antiproliferative activities, thus should be recommended to increase consumption for health.

  5. A trend analysis of global fire activity. Is it land use or climate the main driver?

    NASA Astrophysics Data System (ADS)

    Bistinas, Ioannis; Oom, Duarte; Silva, Joao M. N.; Lopez-Saldaña, Gerardo; Pereira, Jose M. C.

    2016-04-01

    We perform a global trend analysis of active fire counts at 0.5o spatial resolution, using 156 months (January 2001 - December 2013) of MODIS Climate Modelling Grid data (TERRA). We use the Contextual Mann-Kendall (CMK) test to assess the statistical significance at cell level and found that 13% of the global land area displays statistically significant active fire count trends, with a slight predominance of negative trends (50.63% of the total significant cells). We perform the same trend analysis with the unexplained variability (residuals) between active fires and the Fire Weather Index (FWI) that is used as a proxy for climate. There is agreement between the main patterns from the trend analysis coming from the residuals and the active fire trends, implying that the main contemporary fire trends are not climate driven. Spatially coherent patches with significant trends were found in all continents (with the obvious exception of Antarctica). The majority of significant trends occur in areas of high fire incidence, and both increasing and decreasing trends appear to be associated with land use change processes. The analysis reveals large negative trends at the Sahel and between Russia and Kazakhstan, whereas a massive and coherent positive trend appears in southeastern Asia. Smaller patches of positive trends appear in southeastern United States and in Mexico, as well as in Brazil and between Argentina and Paraguay, and in Asia in India. There are also negative trends in Brazil, Argentina and in Australia. The study highlights the land use activities as the main driver of these trends, but also the need for data driven analyses and longer time series for future studies in order to gain better knowledge on fire occurrence.

  6. Antioxidative activity of Rosmarinus officinalis L. essential oil compared to its main components.

    PubMed

    Wang, W; Wu, N; Zu, Y G; Fu, Y J

    2008-06-01

    This study was designed to examine the in vitro antioxidant activities of Rosmarinus officinalis L. essential oil compared to three of its main components (1,8-cineole, α-pinene, β-pinene). GC-MS analysis of the essential oil resulted in the identification of 19 compounds, representing 97.97% of the oil, the major constituents of the oil were described as 1,8-cineole (27.23%), α-pinene (19.43%), camphor (14.26%), camphene (11.52%) and β-pinene (6.71%). The oil and the components were subjected to screening for their possible antioxidant activity by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and β-carotene bleaching test. In the DPPH test system, free radical-scavenging activity of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were determined to be 62.45%±3.42%, 42.7%±2.5%, 45.61%±4.23% and 46.21%±2.24% (v/v), respectively. In the β-carotene bleaching test system, we tested series concentration of samples to show the antioxidant activities of the oil and its main components, whereas the concentrations providing 50% inhibition (IC50) values of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were 2.04%±0.42%, 4.05%±0.65%, 2.28%±0.23% and 2.56%±0.16% (v/v), respectively. In general, R. officinalis L. essential oil showed greater activity than its components in both systems, and the antioxidant activities of all the tested samples were mostly related to their concentrations. Antioxidant activities of the synthetic antioxidant, ascorbic acid and BHT, were also determined in parallel experiments as positive control.

  7. Osteoblasts Proliferation and Differentiation Stimulating Activities of the Main Components of Epimedii folium

    PubMed Central

    Liu, Mingming; Xu, Haiyan; Ma, Yong; Cheng, Jian; Hua, Zhen; Huang, Guicheng

    2017-01-01

    Background: Osteoporosis is a disease of bones that leads to an increased risk of fracture. Epimedii Folium is commonly used for treating bone fractures and joint diseases for thousands of years in China. Methods: This study was aimed to screen active components, which might have the potency to stimulate osteoblasts proliferation and differentiation in Epimedii Folium. An HPLC method was established to analyze the main components in Epimedii Folium. The MTT and ALP methods were utilized for the assay of osteoblasts proliferation and differentiation activity. Bavachin, a flavonoid compound was treated as the positive control. Results: Totally eight compounds have been identified by comparing their retention time with correspondent standard substances. Icariside I and icariside II significantly stimulated cell proliferation and osteoblasts differentiation. All these compounds were found with a characterized flavonoid structure in each of their molecule backbones. Conclusion: These results lead to a hypothesis that flavonoid monoglycoside structure might be crucial to exhibit the activity. The structure–effect relationship of these compounds with flavonoid monoglycoside structure in mouse primary calvarial osteoblasts needs to be explored in further research. SUMMARY Eight compounds were identified by comparing their retention time with correspondent standard substances.Icariside I and icariside II significantly stimulated cell proliferation and osteoblasts differentiation.Flavonoid monoglycoside structure might be crucial to exhibit the osteoblasts proliferation and differentiation activity. Effects of the main components of Epimedii Folium on osteoblasts proliferation after treating 48 h. Abbreviations used: HPLC: High performance liquid chromatography, MTT: Methylthiazolyldiphenyl - tetrazolium bromide, ALP: Alkaline phosphatase PMID:28216889

  8. Ordinary and Activated Bone Grafts: Applied Classification and the Main Features

    PubMed Central

    Deev, R. V.; Drobyshev, A. Y.; Bozo, I. Y.; Isaev, A. A.

    2015-01-01

    Bone grafts are medical devices that are in high demand in clinical practice for substitution of bone defects and recovery of atrophic bone regions. Based on the analysis of the modern groups of bone grafts, the particularities of their composition, the mechanisms of their biological effects, and their therapeutic indications, applicable classification was proposed that separates the bone substitutes into “ordinary” and “activated.” The main differential criterion is the presence of biologically active components in the material that are standardized by qualitative and quantitative parameters: growth factors, cells, or gene constructions encoding growth factors. The pronounced osteoinductive and (or) osteogenic properties of activated osteoplastic materials allow drawing upon their efficacy in the substitution of large bone defects. PMID:26649300

  9. SUBLIMATION-DRIVEN ACTIVITY IN MAIN-BELT COMET 313P/GIBBS

    SciTech Connect

    Hsieh, Henry H.; Hainaut, Olivier; Novaković, Bojan; Bolin, Bryce; Denneau, Larry; Haghighipour, Nader; Kleyna, Jan; Meech, Karen J.; Schunova, Eva; Wainscoat, Richard J.; Fitzsimmons, Alan; Kokotanekova, Rosita; Snodgrass, Colin; Lacerda, Pedro; Micheli, Marco; Moskovitz, Nick; Wasserman, Lawrence; Waszczak, Adam

    2015-02-10

    We present an observational and dynamical study of newly discovered main-belt comet 313P/Gibbs. We find that the object is clearly active both in observations obtained in 2014 and in precovery observations obtained in 2003 by the Sloan Digital Sky Survey, strongly suggesting that its activity is sublimation-driven. This conclusion is supported by a photometric analysis showing an increase in the total brightness of the comet over the 2014 observing period, and dust modeling results showing that the dust emission persists over at least three months during both active periods, where we find start dates for emission no later than 2003 July 24 ± 10 for the 2003 active period and 2014 July 28 ± 10 for the 2014 active period. From serendipitous observations by the Subaru Telescope in 2004 when the object was apparently inactive, we estimate that the nucleus has an absolute R-band magnitude of H{sub R} = 17.1 ± 0.3, corresponding to an effective nucleus radius of r{sub e} ∼ 1.00 ± 0.15 km. The object’s faintness at that time means we cannot rule out the presence of activity, and so this computed radius should be considered an upper limit. We find that 313P’s orbit is intrinsically chaotic, having a Lyapunov time of T{sub l} = 12,000 yr and being located near two three-body mean-motion resonances with Jupiter and Saturn, 11J-1S-5A and 10J+12S-7A, yet appears stable over >50 Myr in an apparent example of stable chaos. We furthermore find that 313P is the second main-belt comet, after P/2012 T1 (PANSTARRS), to belong to the ∼155 Myr old Lixiaohua asteroid family.

  10. Beam scanning offset Cassegrain reflector antennas by subreflector movement

    NASA Technical Reports Server (NTRS)

    Lapean, James W., Jr.; Stutzman, Warren L.

    1994-01-01

    In 1987 a NASA panel recommended the creation of the Mission to Planet Earth. This mission was intended to apply to remote sensing experience of the space community to earth remote sensing to enhance the understanding of the climatological processes of our planet and to determine if, and to what extent, the hydrological cycle of Earth is being affected by human activity. One of the systems required for the mission was a wide scanning, high gain reflector antenna system for use in radiometric remote sensing from geostationary orbit. This work describes research conducted at Virginia Tech into techniques for beam scanning offset Cassegrain reflector antennas by subreflector translation and rotation. Background material relevant to beam scanning antenna systems and offset Cassegrain reflector antenna system is presented. A test case is developed based on the background material. The test case is beam scanned using two geometrical optics methods of determining the optimum subreflector position for the desired scanned beam direction. Physical optics far-field results are given for the beam scanned systems. The test case system is found to be capable of beam scanning over a range of 35 half-power beamwidths while maintaining a 90 percent beam efficiency or 50 half-power beamwidths while maintaining less than l dB of gain loss during scanning.

  11. Variation in contents of main active components and antioxidant activity in leaves of different pigeon pea cultivars during growth.

    PubMed

    Wei, Zuo-Fu; Jin, Shuang; Luo, Meng; Pan, You-Zhi; Li, Ting-Ting; Qi, Xiao-Lin; Efferth, Thomas; Fu, Yu-Jie; Zu, Yuan-Gang

    2013-10-23

    Pigeon pea is an important and multiuse grain legume crop, and its leaves are a very valuable natural resource. To obtain a high-quality biological resource, it is necessary to choose the excellent cultivar and determine the appropriate harvest time. In this study, the variation in contents of main active components and antioxidant activity in leaves of six pigeon pea cultivars during growth were investigated. The level of each individual active component significantly varied during growth, but with a different pattern, and this variation was different among cultivars. Flavonoid glycosides orientin, vitexin, and apigenin-6,8-di-C-α-L-arabinopyranoside showed two peak values at mid-late and final stages of growth in most cases. Pinostrobin chalcone, longistyline C, and cajaninstilbene acid showed remarkablely higher values at the mid-late stage of growth than at other stages. Pinostrobin had an extremely different variation pattern compared to other active components. Its content was the highest at the earlier stage of growth. Principal component analysis (PCA) revealed that vitexin and apigenin-6,8-di-C-α-L-arabinopyranoside were mainly responsible for distinguishing cultivars analyzed. In a comprehensive consideration, the leaves should preferentially be harvested at the 135th day after sowing when the level of active components and antioxidant activity reached higher values. Cultivars ICP 13092, ICPL 87091, and ICPL 96053 were considered to be excellent cultivars with high antioxidant activity. Our findings can provide valuable information for producing a high-quality pigeon pea resource.

  12. Structure of the SARS coronavirus main proteinase as an active C{sub 2} crystallographic dimer

    SciTech Connect

    Xu, Ting; Ooi, Amy; Lee, Hooi Chen; Wilmouth, Rupert; Liu, Ding Xiang; Lescar, Julien

    2005-11-01

    An orthorhombic crystal form of the SARS CoV main proteinase diffracting to a resolution of 1.9 Å is reported. The conformation of residues in the catalytic site indicates an active enzyme. The 34 kDa main proteinase (M{sup pro}) from the severe acute respiratory syndrome coronavirus (SARS-CoV) plays an important role in the virus life cycle through the specific processing of viral polyproteins. As such, SARS-CoV M{sup pro} is a key target for the identification of specific inhibitors directed against the SARS virus. With a view to facilitating the development of such compounds, crystals were obtained of the enzyme at pH 6.5 in the orthorhombic space group P2{sub 1}2{sub 1}2 that diffract to a resolution of 1.9 Å. These crystals contain one monomer per asymmetric unit and the biologically active dimer is generated via the crystallographic twofold axis. The conformation of the catalytic site indicates that the enzyme is active in the crystalline form and thus suitable for structure-based inhibition studies.

  13. Selenium contents in tobacco and main stream cigarette smoke determined using neutron activation analysis

    SciTech Connect

    Sorak-Pokrajac, M.; Dermelj, M.; Slejkovec, Z.

    1994-01-01

    In the domain of the essential trace elements, the role of selenium is extremely important. As one of the volatile elements it can be partly absorbed through the pulmonary system during smoking and transported to different organs of the body. Thus a knowledge of its concentration levels in various sorts of tobacco and in the smoke of commercial cigarettes, as well as in the same type of cigarettes from plants treated with selenium, is of interest for various research fields. The purpose of this contribution is to present reliable quantitative data on selenium contents in tobacco, soil, and main stream cigarette smoke, obtained by destructive neutron activation analysis.

  14. Short History of Fixed-Reflector Radio Telescopes

    NASA Astrophysics Data System (ADS)

    Strom, R. G.

    2016-02-01

    From the 66 m parabolic reflector built in 1947 at Jodrell Bank to the 305 m Arecibo dish completed nearly two decades later, radio astronomers in the early days experimented with fixed reflecting mirrors to achieve large collecting areas. In this brief history I will consider the over half-dozen such instruments (of which I am aware) built by 1970, and their main achievements. I will discuss the likely reasons for the success of some of these telescopes, as well as their short-comings, and the lessons for future instruments like FAST.

  15. The design of the central-axis reflector (ZAS)

    NASA Astrophysics Data System (ADS)

    Huegenell, Hermann

    1989-04-01

    The design principle of the central-axis reflector, a segmented-mirror telescope, is presented. The inventions relate mainly to the optical system and to the tracking apparatus. A large number of small individual mirror bodies, ground off-axis (hexagonal/polygonal), produce one primary mirror with closed circular aperture when joined together. The overall design of the tracking apparatus results directly (and thus without unnecessary adornment) from the two planes of motion which have been reduced to a minimum but which are required for tracking of the telescope.

  16. Enhanced imaging of reflector antenna surface distortion using microwave holography

    NASA Technical Reports Server (NTRS)

    Gilmore, Sean W.; Rudduck, Roger C.

    1989-01-01

    Two signal processing techniques are discussed that improve the accuracy of a microwave holographic measurement by removing unwanted signals from the aperture distribution: pattern simulation and subtraction, and time domain filtering. Pattern simulation and subtraction involves modeling unwanted scattering mechanisms and then removing them from the measured far-field data. Measurements taken on a focal point geometry and a Cassegrain geometry at 11 GHz were processed by the holographic analysis system. Pattern simulation and subtraction was applied to both geometries. Surface deformation profiles generated for the Cassegrain antenna by this system were compared to an optical measurement of the main reflector surface.

  17. High-Precision Shape Control of In-Space Deployable Large Membrane/Thin-Shell Reflectors

    NASA Technical Reports Server (NTRS)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    This innovation has been developed to improve the resolutions of future spacebased active and passive microwave antennas for earth-science remote sensing missions by maintaining surface figure precisions of large membrane/thin-shell reflectors during orbiting. The intention is for these sensing instruments to be deployable at orbit altitudes one or two orders of magnitude higher than Low Earth Orbit (LEO), but still being able to acquire measurements at spatial resolution and sensitivity similar to those of LEO. Because active and passive microwave remote sensors are able to penetrate through clouds to acquire vertical profile measurements of geophysical parameters, it is desirable to elevate them to the higher orbits to obtain orbital geometries that offer large spatial coverage and more frequent observations. This capability is essential for monitoring and for detailed understanding of the life cycles of natural hazards, such as hurricanes, tropical storms, flash floods, and tsunamis. Major components of this high-precision antenna-surface-control system include a membrane/thin shell reflector, a metrology sensor, a controller, actuators, and corresponding power amplifier and signal conditioning electronics (see figure). Actuators are attached to the back of the reflector to produce contraction/ expansion forces to adjust the shape of the thin-material reflector. The wavefront-sensing metrology system continuously measures the surface figure of the reflector, converts the surface figure to digital data and feeds the data to the controller. The controller determines the control parameters and generates commands to the actuator system. The flexible, piezoelectric polymer actuators are thus activated, providing the control forces needed to correct any distortions that exist in the reflector surface. Piezoelectric polymer actuators are very thin and flexible. They can be implemented on the back of the membrane/thin-shell reflector without introducing significant

  18. Atrazine and its main metabolites alter the locomotor activity of larval zebrafish (Danio rerio).

    PubMed

    Liu, Zhenzhen; Wang, Yueyi; Zhu, Zhihong; Yang, Enlu; Feng, Xiayan; Fu, Zhengwei; Jin, Yuanxiang

    2016-04-01

    Atrazine (ATZ) and its main chlorometabolites, i.e., diaminochlorotriazine (DACT), deisopropylatrazine (DIP), and deethylatrazine (DE), have been widely detected in aquatic systems near agricultural fields. However, their possible effects on aquatic animals are still not fully understood. In this study, it was observed that several developmental endpoints such as the heart beat, hatchability, and morphological abnormalities were influenced by ATZ and its metabolites in different developmental stages. In addition, after 5 days of exposure to 30, 100, 300 μg L(-1) ATZ and its main chlorometabolites, the swimming behaviors of larval zebrafish were significantly disturbed, and the acetylcholinesterase (AChE) activities were consistently inhibited. Our results also demonstrate that ATZ and its main chlorometabolites are neuroendocrine disruptors that impact the expression of neurotoxicity-related genes such as Ache, Gap43, Gfap, Syn2a, Shha, Mbp, Elavl3, Nestin and Ngn1 in early developmental stages of zebrafish. According to our results, it is possible that not only ATZ but also its metabolites (DACT, DIP and DE) have the same or even more toxic effects on different endpoints of the early developmental stages of zebrafish.

  19. Advanced composite materials for precision segmented reflectors

    NASA Technical Reports Server (NTRS)

    Stein, Bland A.; Bowles, David E.

    1988-01-01

    The objective in the NASA Precision Segmented Reflector (PSR) project is to develop new composite material concepts for highly stable and durable reflectors with precision surfaces. The project focuses on alternate material concepts such as the development of new low coefficient of thermal expansion resins as matrices for graphite fiber reinforced composites, quartz fiber reinforced epoxies, and graphite reinforced glass. Low residual stress fabrication methods will be developed. When coupon specimens of these new material concepts have demonstrated the required surface accuracies and resistance to thermal distortion and microcracking, reflector panels will be fabricated and tested in simulated space environments. An important part of the program is the analytical modeling of environmental stability of these new composite materials concepts through constitutive equation development, modeling of microdamage in the composite matrix, and prediction of long term stability (including viscoelasticity). These analyses include both closed form and finite element solutions at the micro and macro levels.

  20. Advanced deployable reflectors for communications satellites

    NASA Astrophysics Data System (ADS)

    Lowe, Elvin; Josephs, Michael; Hedgepeth, John

    1993-02-01

    This paper discusses a concept for a deployable mesh reflector for large spacecraft antennas and the processes used in design, fabrication and testing. A set of overall reflector requirements such as stowed volume, deployed diameter and RF loss derived from system specifications are presented. The development of design and analysis tools to allow parametric studies such as facet size, number of ribs and number of rib segments is discussed. CATIA (a commercially available three-dimensional design and analysis tool) is used to perform kinematic analyses as well as to establish the database to be used by the several groups participating in the development is examined. Results of trade studies performed to reduce cost with minimum risk to product delivery are included. A thirty foot reflector has been built and tested.

  1. Test progress on the electrostatic membrane reflector

    NASA Technical Reports Server (NTRS)

    Mihora, D. J.

    1981-01-01

    An extemely lightweight type of precision reflector antenna, being developed for potential deployment from the space shuttle, uses electrostatic forces to tension a thin membrane and form it into a concave reflector surface. The typical shuttle-deployed antenna would have a diameter of 100 meters and an RMS surface smoothness of 10 to 1 mm for operation at 1 to 10 GHz. NASA Langley Research Center built and is currently testing a subscale (16 foot diameter) model of the membrane reflector portion of such an antenna. Preliminary test results and principal factors affecting surface quality are addressed. Factors included are the effect of the perimeter boundary, splicing of the membrane, the long-scale smoothness of commercial membranes, and the spatial controllability of the membrane using voltage adjustments to alter the electrostatic pressure. Only readily available commercial membranes are considered.

  2. The Freeform Reflector for Uniform Rectangular Illumination

    NASA Astrophysics Data System (ADS)

    Ding, Yi; Gu, Pei-Fu; Zheng, Zhen-Rong

    2007-12-01

    Energy from the source was rearranged through reflection by a freeform reflector, in order to get uniform rectangular illumination. The numerical results of partial differential equation sets were investigated to obtain the freeform reflector and these equations were obtained upon the determination of the characters of source and the desired illumination. As an example, a light emitting diode (LED) with a Lambertian light-emitting surface of 1 × 1 mm2 and a viewing angle of 120° was applied as the source, and the target plane was a 4:3 rectangle with uniform illumination. The projective length of the reflector on x-axis is about 23 mm, and on y-axis is about 21 mm. Thus the illumination system is very compact.

  3. Composite materials for precision space reflector panels

    NASA Technical Reports Server (NTRS)

    Tompkins, Stephen S.; Funk, Joan G.; Bowles, David E.; Towell, Timothy W.; Connell, John W.

    1992-01-01

    One of the critical technology needs of large precision reflectors for future astrophysical and optical communications satellites lies in the area of structural materials. Results from a materials research and development program at NASA Langley Research Center to provide materials for these reflector applications are discussed. Advanced materials that meet the reflector panel requirements are identified, and thermal, mechanical and durability properties of candidate materials after exposure to simulated space environments are compared. A parabolic, graphite-phenolic honeycomb composite panel having a surface accuracy of 70.8 microinches rms and an areal weight of 1.17 lbm/sq ft was fabricated with T50/ERL1962 facesheets, a PAEI thermoplastic surface film, and Al and SiO(x) coatings.

  4. Global circulation as the main source of cloud activity on Titan.

    PubMed

    Rodriguez, Sébastien; Le Mouélic, Stéphane; Rannou, Pascal; Tobie, Gabriel; Baines, Kevin H; Barnes, Jason W; Griffith, Caitlin A; Hirtzig, Mathieu; Pitman, Karly M; Sotin, Christophe; Brown, Robert H; Buratti, Bonnie J; Clark, Roger N; Nicholson, Phil D

    2009-06-04

    Clouds on Titan result from the condensation of methane and ethane and, as on other planets, are primarily structured by circulation of the atmosphere. At present, cloud activity mainly occurs in the southern (summer) hemisphere, arising near the pole and at mid-latitudes from cumulus updrafts triggered by surface heating and/or local methane sources, and at the north (winter) pole, resulting from the subsidence and condensation of ethane-rich air into the colder troposphere. General circulation models predict that this distribution should change with the seasons on a 15-year timescale, and that clouds should develop under certain circumstances at temperate latitudes ( approximately 40 degrees ) in the winter hemisphere. The models, however, have hitherto been poorly constrained and their long-term predictions have not yet been observationally verified. Here we report that the global spatial cloud coverage on Titan is in general agreement with the models, confirming that cloud activity is mainly controlled by the global circulation. The non-detection of clouds at latitude approximately 40 degrees N and the persistence of the southern clouds while the southern summer is ending are, however, both contrary to predictions. This suggests that Titan's equator-to-pole thermal contrast is overestimated in the models and that its atmosphere responds to the seasonal forcing with a greater inertia than expected.

  5. Effects of Chlorophenoxy Herbicides and Their Main Transformation Products on DNA Damage and Acetylcholinesterase Activity

    PubMed Central

    Benfeito, Sofia; Silva, Tiago; Garrido, Jorge; Andrade, Paula B.; Sottomayor, M. J.; Borges, Fernanda; Garrido, E. Manuela

    2014-01-01

    Persistent pesticide transformation products (TPs) are increasingly being detected among different environmental compartments, including groundwater and surface water. However, there is no sufficient experimental data on their toxicological potential to assess the risk associated with TPs, even if their occurrence is known. In this study, the interaction of chlorophenoxy herbicides (MCPA, mecoprop, 2,4-D and dichlorprop) and their main transformation products with calf thymus DNA by UV-visible absorption spectroscopy has been assessed. Additionally, the toxicity of the chlorophenoxy herbicides and TPs was also assessed evaluating the inhibition of acetylcholinesterase activity. On the basis of the results found, it seems that AChE is not the main target of chlorophenoxy herbicides and their TPs. However, the results found showed that the transformation products displayed a higher inhibitory activity when compared with the parent herbicides. The results obtained in the DNA interaction studies showed, in general, a slight effect on the stability of the double helix. However, the data found for 4-chloro-2-methyl-6-nitrophenol suggest that this transformation product can interact with DNA through a noncovalent mode. PMID:24795892

  6. Global circulation as the main source of cloud activity on Titan

    USGS Publications Warehouse

    Rodriguez, S.; Le, Mouelic S.; Rannou, P.; Tobie, G.; Baines, K.H.; Barnes, J.W.; Griffith, C.A.; Hirtzig, M.; Pitman, K.M.; Sotin, C.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2009-01-01

    Clouds on Titan result from the condensation of methane and ethane and, as on other planets, are primarily structured by circulation of the atmosphere. At present, cloud activity mainly occurs in the southern (summer) hemisphere, arising near the pole and at mid-latitudes from cumulus updrafts triggered by surface heating and/or local methane sources, and at the north (winter) pole, resulting from the subsidence and condensation of ethane-rich air into the colder troposphere. General circulation models predict that this distribution should change with the seasons on a 15-year timescale, and that clouds should develop under certain circumstances at temperate latitudes (40??) in the winter hemisphere. The models, however, have hitherto been poorly constrained and their long-term predictions have not yet been observationally verified. Here we report that the global spatial cloud coverage on Titan is in general agreement with the models, confirming that cloud activity is mainly controlled by the global circulation. The non-detection of clouds at latitude 40??N and the persistence of the southern clouds while the southern summer is ending are, however, both contrary to predictions. This suggests that Titans equator-to-pole thermal contrast is overestimated in the models and that its atmosphere responds to the seasonal forcing with a greater inertia than expected. ?? 2009 Macmillan Publishers Limited. All rights reserved.

  7. CHARACTERIZATION OF ACTIVE MAIN BELT OBJECT P/2012 F5 (GIBBS): A POSSIBLE IMPACTED ASTEROID

    SciTech Connect

    Stevenson, R.; Kramer, E. A.; Bauer, J. M.; Masiero, J. R.; Mainzer, A. K.

    2012-11-10

    In this work, we characterize the recently discovered active main belt object P/2012 F5 (Gibbs), which was discovered with a dust trail >7' in length in the outer main belt, 7 months prior to aphelion. We use optical imaging obtained on UT 2012 March 27 to analyze the central condensation and the long trail. We find B-band and R-band apparent magnitudes of 20.96 {+-} 0.04 mag and 19.93 {+-} 0.02 mag, respectively, which give an upper limit on the radius of the nucleus of 2.1 km. The geometric scattering cross-section of material in the trail was {approx}4 Multiplication-Sign 10{sup 8} m{sup 2}, corresponding to a mass of {approx}5 Multiplication-Sign 10{sup 7} kg. Analysis of infrared images taken by the Wide-field Infrared Survey Explorer in 2010 September reveals that the object was below the detection limit, suggesting that it was less active than it was during 2012, or possibly inactive, just six months after it passed through perihelion. We set a 1{sigma} upper limit on its radius during this time of 2.9 km. P/2012 F5 (Gibbs) is dynamically stable in the outer main belt on timescales of {approx}1 Gyr, pointing toward an asteroidal origin. We find that the morphology of the ejected dust is consistent with it being produced by a single event that occurred on UT 2011 July 7 {+-} 20 days, possibly as the result of a collision with a small impactor.

  8. Design of the Central-Axis Reflector (ZAS) and results leading to the Off-Axis Reflector

    NASA Astrophysics Data System (ADS)

    Huegenell, Hermann

    1990-07-01

    The Central-Axis Reflector (ZAS), the design of which is presented, is a segmented mirror telescope. The inventions relate mainly to the optical system and to the tracking apparatus. A number of individual mirror bodies, ground off-axis (hexagonal/polygonal) produce one primary mirror with closed circular aperture when joined together. The overall design of the tracking apparatus results directly (and thus without unnecessary adornment) from the two planes of motion which have been reduced to an obligatory minimum but which are required for tracking of the telescope.

  9. Cryogenic systems for the large deployable reflector

    NASA Technical Reports Server (NTRS)

    Mason, Peter V.

    1988-01-01

    There are five technologies which may have application for Large Deployable Reflector (LDR), one passive and four active. In order of maturity, they are passive stored cryogen systems, and mechanical, sorption, magnetic, and pulse-tube refrigerators. In addition, deep space radiators will be required to reject the heat of the active systems, and may be useful as auxiliary coolers for the stored cryogen systems. Hybrid combinations of these technologies may well be more efficient than any one alone, and extensive system studies will be required to determine the best trade-offs. Stored cryogen systems were flown on a number of missions. The systems are capable of meeting the temperature requirements of LDR. The size and weight of stored cryogen systems are proportional to heat load and, as a result, are applicable only if the low-temperature heat load can be kept small. Systems using chemisorption and physical adsorption for compressors and pumps have received considerable attention in the past few years. Systems based on adiabatic demagnetization of paramagnetic salts were used for refrigeration for many years. Pulse-tube refrigerators were recently proposed which show relatively high efficiency for temperatures in the 60 to 80 K range. The instrument heat loads and operating temperatures are critical to the selection and design of the cryogenic system. Every effort should be made to minimize heat loads, raise operating temperatures, and to define these precisely. No one technology is now ready for application to LDR. Substantial development efforts are underway in all of the technologies and should be monitored and advocated. Magnetic and pulse-tube refrigerators have high potential.

  10. Monte Carlo simulation of moderator and reflector in coal analyzer based on a D-T neutron generator.

    PubMed

    Shan, Qing; Chu, Shengnan; Jia, Wenbao

    2015-11-01

    Coal is one of the most popular fuels in the world. The use of coal not only produces carbon dioxide, but also contributes to the environmental pollution by heavy metals. In prompt gamma-ray neutron activation analysis (PGNAA)-based coal analyzer, the characteristic gamma rays of C and O are mainly induced by fast neutrons, whereas thermal neutrons can be used to induce the characteristic gamma rays of H, Si, and heavy metals. Therefore, appropriate thermal and fast neutrons are beneficial in improving the measurement accuracy of heavy metals, and ensure that the measurement accuracy of main elements meets the requirements of the industry. Once the required yield of the deuterium-tritium (d-T) neutron generator is determined, appropriate thermal and fast neutrons can be obtained by optimizing the neutron source term. In this article, the Monte Carlo N-Particle (MCNP) Transport Code and Evaluated Nuclear Data File (ENDF) database are used to optimize the neutron source term in PGNAA-based coal analyzer, including the material and shape of the moderator and neutron reflector. The optimized targets include two points: (1) the ratio of the thermal to fast neutron is 1:1 and (2) the total neutron flux from the optimized neutron source in the sample increases at least 100% when compared with the initial one. The simulation results show that, the total neutron flux in the sample increases 102%, 102%, 85%, 72%, and 62% with Pb, Bi, Nb, W, and Be reflectors, respectively. Maximum optimization of the targets is achieved when the moderator is a 3-cm-thick lead layer coupled with a 3-cm-thick high-density polyethylene (HDPE) layer, and the neutron reflector is a 27-cm-thick hemispherical lead layer.

  11. Aqueous Volatiles in Hydrothermal fluids from the Main Endeavour Vent Field: Temporal Variability Following Earthquake Activity

    NASA Astrophysics Data System (ADS)

    Seewald, J. S.; Cruse, A. M.; Saccocia, P. J.

    2001-12-01

    Volatile species play a critical role in a broad spectrum of physical, chemical, and biological processes associated with hydrothermal circulation at oceanic spreading centers. Earthquake activity at the Main Endeavour vent field, northern Juan de Fuca Ridge in June 1999 [1] provided and opportunity to assess factors that regulate the flux of volatile species from the oceanic crust to the water column following a rapid change in subsurface reaction zone conditions. High temperature vent fluids were collected in gas-tight samplers at the Main Endeavour field in September 1999, approximately four months after the earthquakes, and again in July 2000, and were analyzed for the abundance of aqueous volatile and non-volatile species. Measured concentrations of aqueous H2, H2S, and CO2 increased substantially in September 1999 relative to pre-earthquake values [2,3], and subsequently decreased in July 2000, while aqueous Cl concentrations initially decreased in 1999 and subsequently increased in 2000. Concentrations of Cl in all fluids were depleted relative to seawater values. Aqueous CH4 and NH3 concentrations decreased in both the 1999 and 2000 samples relative to pre- earthquake values. Variations in Cl concentration of Endeavour fluids reflect varying degrees of phase separation under near critical temperature and pressure conditions. Because volatile species efficiently partition into the vapor phase, variations in their abundance as a function of Cl concentration can be used to constrain conditions of phase separation and fluid-rock interaction. For example, concentrations of volatile species that are not readily incorporated into minerals (CH4 and NH3) correlated weakly with Cl suggesting phase separation was occurring under supercritical conditions after the earthquake activity. In contrast, compositional data for fluids prior to the earthquakes indicate a strong negative correlation between these species and Cl suggesting phase separation under subcritical

  12. WISE/NEOWISE OBSERVATIONS OF ACTIVE BODIES IN THE MAIN BELT

    SciTech Connect

    Bauer, James M.; Mainzer, A. K.; Masiero, Joseph R.; Blauvelt, Erin K.; Cherry, De'Andre; Grav, Tommy; Walker, Russell G.; McMillan, Robert S.; Scotti, James V.; Fernandez, Yan R.; Kramer, Emily; Meech, Karen J.; Tholen, David J.; Riesen, Timm; Urban, Laurie; Khayat, Alain; Lisse, Carey M.; Cutri, Roc M.; Dailey, John W.; Pearman, George; Collaboration: WISE Team; and others

    2012-03-01

    We report results based on mid-infrared photometry of five active main belt objects (AMBOs) detected by the Wide-field Infrared Survey Explorer (WISE) spacecraft. Four of these bodies, P/2010 R2 (La Sagra), 133P/Elst-Pizarro, (596) Scheila, and 176P/LINEAR, showed no signs of activity at the time of the observations, allowing the WISE detections to place firm constraints on their diameters and albedos. Geometric albedos were in the range of a few percent, and on the order of other measured comet nuclei. P/2010 A2 was observed on 2010 April 2-3, three months after its peak activity. Photometry of the coma at 12 and 22 {mu}m combined with ground-based visible-wavelength measurements provides constraints on the dust particle mass distribution (PMD), dlog n/dlog m, yielding power-law slope values of {alpha} = -0.5 {+-} 0.1. This PMD is considerably more shallow than that found for other comets, in particular inbound particle fluence during the Stardust encounter of comet 81P/Wild 2. It is similar to the PMD seen for 9P/Tempel 1 in the immediate aftermath of the Deep Impact experiment. Upper limits for CO{sub 2} and CO production are also provided for each AMBO and compared with revised production numbers for WISE observations of 103P/Hartley 2.

  13. Dual annular rotating "windowed" nuclear reflector reactor control system

    DOEpatents

    Jacox, Michael G.; Drexler, Robert L.; Hunt, Robert N. M.; Lake, James A.

    1994-01-01

    A nuclear reactor control system is provided in a nuclear reactor having a core operating in the fast neutron energy spectrum where criticality control is achieved by neutron leakage. The control system includes dual annular, rotatable reflector rings. There are two reflector rings: an inner reflector ring and an outer reflector ring. The reflectors are concentrically assembled, surround the reactor core, and each reflector ring includes a plurality of openings. The openings in each ring are capable of being aligned or non-aligned with each other. Independent driving means for each of the annular reflector rings is provided so that reactor criticality can be initiated and controlled by rotation of either reflector ring such that the extent of alignment of the openings in each ring controls the reflection of neutrons from the core.

  14. An investigation into shape and vibration control of space antenna reflectors

    NASA Astrophysics Data System (ADS)

    Susheel, C. K.; Kumar, Rajeev; Chauhan, Vishal S.

    2016-12-01

    A study into the shape and active vibration control of antenna reflectors, an important member of the space structures, is carried out in this paper. Geometric nonlinear analysis is considered for performance evaluation of antenna reflectors, as very high precision is an important aspect of space structures. An effort has been made to demonstrate the importance of functionally graded materials in space structures. Piezolaminated structures have been used for shape and vibration control applications for many years. However, due to the problems like debonding and delamination, the reliability of these materials in space structures is still uncertain. To overcome these problems, patches made of functionally graded piezoelectric material (FGPM) are used for shape and vibration control of antenna reflectors in this investigation. FGPM patches are also used to demonstrate the beam-shaping and beam-steering application of antenna reflectors. For the active vibration control application, a fuzzy-logic controller (FLC) is designed and validated with the experimental results. An experimental study has been conducted for comparing the performance of different controllers in the context of vibration reduction. The FLC is then used for active vibration control of an antenna reflector under the application of thermal impact and sinusoidal loading.

  15. The Main Sequences of Star-forming Galaxies and Active Galactic Nuclei at High Redshift

    NASA Astrophysics Data System (ADS)

    Mancuso, C.; Lapi, A.; Shi, J.; Cai, Z.-Y.; Gonzalez-Nuevo, J.; Béthermin, M.; Danese, L.

    2016-12-01

    We provide a novel, unifying physical interpretation on the origin, average shape, scatter, and cosmic evolution for the main sequences of star-forming galaxies and active galactic nuclei (AGNs) at high redshift z≳ 1. We achieve this goal in a model-independent way by exploiting: (i) the redshift-dependent star formation rate functions based on the latest UV/far-IR data from HST/Herschel, and related statistics of strong gravitationally lensed sources; (ii) deterministic evolutionary tracks for the history of star formation and black hole accretion, gauged on a wealth of multiwavelength observations including the observed Eddington ratio distribution. We further validate these ingredients by showing their consistency with the observed galaxy stellar mass functions and AGN bolometric luminosity functions at different redshifts via the continuity equation approach. Our analysis of the main sequence for high-redshift galaxies and AGNs highlights that the present data are consistently interpreted in terms of an in situ coevolution scenario for star formation and black hole accretion, envisaging these as local, time-coordinated processes.

  16. The dynamics and morphology of the Main Ionospheric Trough during storm active periods

    NASA Astrophysics Data System (ADS)

    Przepiórka, Dorota; Matyjasiak, Barbara; Rothkaehl, Hanna

    2015-04-01

    Mid-latitude trough, or Main Ionospheric Trough (MIT) lies on the equatorward edge of the auroral oval and plays a role as a boundary layer between the region of closed and open magnetic field lines. Here the magnetosphere-ionosphere-thermosphere coupling processes can be studied because MIT is controlled by both Earth's magnetic field and the IMF (Interplanetary Magnetic Field). MIT is well known from its magnetic storm phase dependence. With the storm onset the structure moves to lower latitudes. It narrows and deepens with the increase of the storm. During recovery phase the intensification of the electromagnetic emissions and energetic particle precipitation can be observed within the latitudes of MIT, what may explain the high variability of the trough location and shape in that time. Analysed magnetic storms have fallen into solar activity minimum, nevertheless causing strong modifications in Earth's plasma environment.

  17. [Main types of activity of specialists of medical and preventive profile in military hospitals].

    PubMed

    Akimkin, V G; Azarov, I I; Volynkov, I O; Bobylev, V A

    2015-09-01

    Infection prevention in medical organizations is an essential task to ensure quality of medical care and create a safe environment for patients and medical staff. The main task of a specialist of medical and preventive profile in the hospital is to maintain sanitary and epidemiological safety and control fulfillment of a complex of preventive measures. To achieve these goals specialists monitor epidemiological and microbiological fulfilment of the implementation and effectiveness of preventive measures, which allow to except infection entry to the hospital and possible carrying out beyond the hospital, occurrence and spread of disease. An obligatory activity of the specialist of medical and preventive profile in the hospital is a scientific and methodical work. The authors propose adoption of preventive structural subdivisions to the state largest diversified military hospitals.

  18. The Discovery of Solar-like Activity Cycles Beyond the End of the Main Sequence?

    NASA Astrophysics Data System (ADS)

    Route, Matthew

    2016-10-01

    The long-term magnetic behavior of objects near the cooler end of the stellar main sequence is poorly understood. Most theoretical work on the generation of magnetism in these ultracool dwarfs (spectral type ≥M7 stars and brown dwarfs) suggests that their magnetic fields should not change in strength and direction. Using polarized radio emission measurements of their magnetic field orientations, I demonstrate that these cool, low-mass, fully convective objects appear to undergo magnetic polarity reversals analogous to those that occur on the Sun. This powerful new technique potentially indicates that the patterns of magnetic activity displayed by the Sun continue to exist, despite the fully convective interiors of these objects, in contravention of several leading theories of the generation of magnetic fields by internal dynamos.

  19. WATER-ICE-DRIVEN ACTIVITY ON MAIN-BELT COMET P/2010 A2 (LINEAR)?

    SciTech Connect

    Moreno, F.; Ortiz, J. L.; Cabrera-Lavers, A.; Augusteijn, T.; Liimets, T.; Lindberg, J. E.; Pursimo, T.; RodrIguez-Gil, P.; Vaduvescu, O.

    2010-08-01

    The dust ejecta of Main-Belt Comet P/2010 A2 (LINEAR) have been observed with several telescopes at the Observatorio del Roque de los Muchachos on La Palma, Spain. Application of an inverse dust tail Monte Carlo method to the images of the dust ejecta from the object indicates that a sustained, likely water-ice-driven, activity over some eight months is the mechanism responsible for the formation of the observed tail. The total amount of the dust released is estimated to be 5 x 10{sup 7} kg, which represents about 0.3% of the nucleus mass. While the event could have been triggered by a collision, this cannot be determined from the currently available data.

  20. Identification and quantification of the main active anticancer alkaloids from the root of Glaucium flavum.

    PubMed

    Bournine, Lamine; Bensalem, Sihem; Wauters, Jean-Noël; Iguer-Ouada, Mokrane; Maiza-Benabdesselam, Fadila; Bedjou, Fatiha; Castronovo, Vincent; Bellahcène, Akeila; Tits, Monique; Frédérich, Michel

    2013-12-02

    Glaucium flavum is used in Algerian folk medicine to remove warts (benign tumors). Its local appellations are Cheqiq el-asfar and Qarn el-djedyane. We have recently reported the anti-tumoral activity of Glaucium flavum root alkaloid extract against human cancer cells, in vitro and in vivo. The principal identified alkaloid in the extract was protopine. This study aims to determine which component(s) of Glaucium flavum root extract might possess potent antitumor activity on human cancer cells. Quantitative estimation of Glaucium flavum alkaloids was realized by HPLC-DAD. Glaucium flavum effect on human normal and cancer cell viability was determined using WST-1 assay. Quantification of alkaloids in Glaucium flavum revealed that the dried root part contained 0.84% of protopine and 0.07% of bocconoline (w/w), while the dried aerial part contained only 0.08% of protopine, glaucine as the main alkaloid, and no bocconoline. In vitro evaluation of the growth inhibitory activity on breast cancer and normal cells demonstrated that purified protopine did not reproduce the full cytotoxic activity of the alkaloid root extract on cancer cell lines. On the other hand, bocconoline inhibited strongly the viability of cancer cells with an IC50 of 7.8 µM and only a low cytotoxic effect was observed against normal human cells. Our results showed for the first time that protopine is the major root alkaloid of Glaucium flavum. Finally, we are the first to demonstrate a specific anticancer effect of Glaucium flavum root extract against breast cancer cells, which can be attributed, at least in part, to bocconoline.

  1. Slip Rates of Main Active Fault Zones Through Turkey Inferred From GPS Observations

    NASA Astrophysics Data System (ADS)

    Ozener, H.; Aktug, B.; Dogru, A.; Tasci, L.; Acar, M.; Emre, O.; Yilmaz, O.; Turgut, B.; Halicioglu, K.; Sabuncu, A.; Bal, O.; Eraslan, A.

    2015-12-01

    Active Fault Map of Turkey was revised and published by General Directorate of Mineral Research and Exploration in 2012. This map reveals that there are about 500 faults can generate earthquakes.In order to understand the earthquake potential of these faults, it is needed to determine the slip rates. Although many regional and local studies were performed in the past, the slip rates of the active faults in Turkey have not been determined. In this study, the block modelling, which is the most common method to produce slip rates, will be done. GPS velocities required for block modeling is being compiled from the published studies and the raw data provided then velocity field is combined. To form a homogeneous velocity field, different stochastic models will be used and the optimal velocity field will be achieved. In literature, GPS site velocities, which are computed for different purposes and published, are combined globally and this combined velocity field are used in the analysis of strain accumulation. It is also aimed to develop optimal stochastic models to combine the velocity data. Real time, survey mode and published GPS observations is being combined in this study. We also perform new GPS observations. Furthermore, micro blocks and main fault zones from Active Fault Map Turkey will be determined and homogeneous velocity field will be used to infer slip rates of these active faults. Here, we present the result of first year of the study. This study is being supported by THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TURKEY (TUBITAK)-CAYDAG with grant no. 113Y430.

  2. Advanced sunflower antenna concept development. [stowable reflectors

    NASA Technical Reports Server (NTRS)

    Archer, J. S.

    1980-01-01

    The feasibility of stowing large solid antenna reflectors in the shuttle was demonstrated for applications with 40 foot apertures at frequencies of 100 GHz. Concepts allowing extension of the basic concept to 80-foot apertures operable at 60 GHz were identified.

  3. Distortion compensation techniques for large reflector antennas

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.

    2001-01-01

    The high-frequency limit of reflector antennas is usually governed by the magnitude of the surface error. Whereas little can be done for the high-spatial frequency portion of this error, there are various techniques that can be employed to compensate for large-scale surface errors due to gravity induced distortions for spacecraft antennas.

  4. Wirelessly Controllable Inflated Electroactive Polymer (EAP) Reflectors

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart; Badescu, Mircea

    2005-01-01

    Inflatable membrane reflectors are attractive for deployable, large aperture, lightweight optical and microwave systems in micro-gravity space environment. However, any fabrication flaw or temperature variation may results in significant aberration of the surface. Even for a perfectly fabricated inflatable membrane mirror with uniform thickness, theory shows it will form a Hencky curve surface but a desired parabolic or spherical surface. Precision control of the surfaceshape of extremely flexible membrane structures is a critical challenge for the success of this technology. Wirelessly controllable inflated reflectors made of electroactive polymers (EAP) are proposed in this paper. A finite element model was configured to predict the behavior of the inflatable EAP membranes under pre-strains, pressures and distributed electric charges on the surface. To explore the controllability of the inflatable EAP reflectors, an iteration algorism was developed to find the required electric actuation for correcting the aberration of the Hencky curve to the desired parabolic curve. The correction capability of the reflectors with available EAP materials was explored numerically and is presented in this paper.

  5. Electrically thin flat lenses and reflectors.

    PubMed

    Ruphuy, Miguel; Siddiqui, Omar; Ramahi, Omar M

    2015-09-01

    We introduce electrically thin dielectric lenses and reflectors that focus a plane wave based on the principles of phase compensation and constructive wave interference. Phase compensation is achieved by arranging thin rectangular slabs having different dielectric permittivity according to a permittivity profile obtained through analytic design equations. All incident rays parallel to the optical axis converge to a focal point with equalized optical paths resulting in constructive interference. Plane wave simulations indicate strong focusing, even in the presence of impedance mismatch between free space and the dielectric layers composing the lens. We demonstrate focusing at 9.45 GHz using a lens fabricated with commercially available dielectric materials. In addition to focusing, the flat lens proposed here demonstrates relatively high power gain at the focal point. We also present a flat reflector based on the same concept. We believe that the proposed dielectric lens and reflector are strong candidates to replace heavy metallic dishes and reflectors used in a variety of applications, especially satellites.

  6. Welding torch with arc light reflector

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S. (Inventor)

    1986-01-01

    A welding torch arc light reflector is disclosed for welding torches having optical viewing systems. A schematic of a welding torch having an internal coaxial viewing system consisting of a lens which focuses the field of view of the weld scene of the workpiece onto the end of the fiberoptic bundle is provided. The transmitted image of the fiberoptic bundle is provided to a camera lens which focuses it onto a TV sensor array for transmission. To improve the parity of the image of the monitoring system, an arc light reflector is shown fitted to the end of the torch housing or gas cup. The arc light reflector has an internal conical section portion which is polished to serve as a mirror which reflects the bright arc light back onto the darker areas of the weld area and thereby provides a more detailed image for the monitoring system. The novelty of the invention lies in the use of an arc light reflector on welding torches having optical viewing systems.

  7. Welding torch with arc light reflector

    NASA Astrophysics Data System (ADS)

    Gordon, Stephen S.

    1986-12-01

    A welding torch arc light reflector is disclosed for welding torches having optical viewing systems. A schematic of a welding torch having an internal coaxial viewing system consisting of a lens which focuses the field of view of the weld scene of the workpiece onto the end of the fiberoptic bundle is provided. The transmitted image of the fiberoptic bundle is provided to a camera lens which focuses it onto a TV sensor array for transmission. To improve the parity of the image of the monitoring system, an arc light reflector is shown fitted to the end of the torch housing or gas cup. The arc light reflector has an internal conical section portion which is polished to serve as a mirror which reflects the bright arc light back onto the darker areas of the weld area and thereby provides a more detailed image for the monitoring system. The novelty of the invention lies in the use of an arc light reflector on welding torches having optical viewing systems.

  8. Multimode Analysis of Bragg Reflectors for Cyclotron Maser Applications

    DTIC Science & Technology

    1991-02-16

    exponentially with distance in the reflector. The spatial dependance of the TMI I mode is oscillatory. Figure 3 shows the frequency dependence of the...mode reflector for a CARM oscillator resonator. Figure 4 shows the frequency dependance of the reflection and mode conversion in the reflector. In order

  9. Heavy reflector experiments in the IPEN/MB-01 reactor: Stainless steel, carbon steel and nickel

    SciTech Connect

    Santos, Adimir dos; Andrade e Silva, Graciete Simoes de; Jerez, Rogerio; Liambos Mura, Luis Felipe; Fuga, Rinaldo

    2013-05-06

    New experiments devoted to the measurements of physical parameters of a light water core surrounded by a heavy reflector were performed in the IPEN/MB-01 research reactor facility. These experiments comprise three sets of heavy reflector (SS-304, Carbon Steel, and Nickel) in a form of laminates around 3 mm thick. Each set was introduced individually in the west face of the core of the IPEN/MB-01 reactor. The aim here is to provide high quality experimental data for the interpretation and validation of the SS-304 heavy reflector calculation methods. The experiments of Carbon Steel, which is composed mainly of iron, and Nickel were performed to provide a consistent and an interpretative check for the SS-304 reflector experiment. The experimental results comprise critical control bank positions, temperatures and reactivities as a function of the number of the plates. Particularly to the case of Nickel, the experimental data are unique of its kind. The theoretical analysis was performed by MCNP-5 with the nuclear data library ENDF/B-VII.0. It was shown that this nuclear data library has a very good performance up to thirteen plates and overestimates the reactivity for higher number of plates independently of the type of the reflector.

  10. Antibacterial activity and anticancer activity of Rosmarinus officinalis L. essential oil compared to that of its main components.

    PubMed

    Wang, Wei; Li, Nan; Luo, Meng; Zu, Yuangang; Efferth, Thomas

    2012-03-05

    In this study, Rosmarinus officinalis L. essential oil and three of its main components 1,8-cineole (27.23%), α-pinene (19.43%) and β-pinene (6.71%) were evaluated for their in vitro antibacterial activities and toxicology properties. R. officinalis L. essential oil possessed similar antibacterial activities to α-pinene, and a little bit better than β-pinene, while 1,8-cineole possessed the lowest antibacterial activities. R. officinalis L. essential oil exhibited the strongest cytotoxicity towards three human cancer cells. Its inhibition concentration 50% (IC₅₀) values on SK-OV-3, HO-8910 and Bel-7402 were 0.025‰, 0.076‰ and 0.13‰ (v/v), respectively. The cytotoxicity of all the test samples on SK-OV-3 was significantly stronger than on HO-8910 and Bel-7402. In general, R. officinalis L. essential oil showed greater activity than its components in both antibacterial and anticancer test systems, and the activities were mostly related to their concentrations.

  11. Interpolation solutions for the problem of synthesis of dual-shaped offset reflector antennas

    NASA Technical Reports Server (NTRS)

    Jervase, Joseph A.; Mittra, Raj; Galindo-Israel, Victor; Imbriale, W.

    1989-01-01

    Synthesis of dual-shaped offset reflector antennas to control the exit aperture distribution of amplitude and phase has received considerable attention in recent years. For a given feed illumination and desired aperture field distribution, an exact formulation of the problem of simultaneously synthesizing the shapes of the sub and main reflectors was presented recently by Galindo-Israel et al. (1987) in terms of a set of nonlinear first-order differential equations. In this paper, a numerical approach to solving these equations is discussed which circumvents some of the difficulties encountered by Galindo-Israel et al., particularly for small values of theta.

  12. Analysis of the Thermo-Elastic Response of Space Reflectors to Simulated Space Environment

    NASA Astrophysics Data System (ADS)

    Allegri, G.; Ivagnes, M. M.; Marchetti, M.; Poscente, F.

    2002-01-01

    The evaluation of space environment effects on materials and structures is a key matter to develop a proper design of long duration missions: since a large part of satellites operating in the earth orbital environment are employed for telecommunications, the development of space antennas and reflectors featured by high dimensional stability versus space environment interactions represents a major challenge for designers. The structural layout of state of the art space antennas and reflectors is very complex, since several different sensible elements and materials are employed: particular care must be placed in evaluating the actual geometrical configuration of the reflectors operating in the space environment, since very limited distortions of the designed layout can produce severe effects on the quality of the signal both received and transmitted, especially for antennas operating at high frequencies. The effects of thermal loads due to direct sunlight exposition and to earth and moon albedo can be easily taken into account employing the standard methods of structural analysis: on the other hand the thermal cycling and the exposition to the vacuum environment produce a long term damage accumulation which affects the whole structure. The typical effects of the just mentioned exposition are the outgassing of polymeric materials and the contamination of the exposed surface, which can affect sensibly the thermo-mechanical properties of the materials themselves and, therefore, the structural global response. The main aim of the present paper is to evaluate the synergistic effects of thermal cycling and of the exposition to high vacuum environment on an innovative antenna developed by Alenia Spazio S.p.a.: to this purpose, both an experimental and numerical research activity has been developed. A complete prototype of the antenna has been exposed to the space environment simulated by the SAS facility: this latter is constituted by an high vacuum chamber, equipped by

  13. Parametric x-ray FEL operating with external Bragg reflectors

    SciTech Connect

    Baryshevsky, V.G.; Batrakov, K.G.; Dubovskaya, I.Ya.

    1995-12-31

    In the crystal X-ray FELs using channeling and parametric quasi-Cherenkov mechanisms of spontaneous radiation were considered as versions of FEL allowing, in principle, to obtain coherent X-ray source. In this case a crystal is both radiator and resonator for X-rays emitted by a particle beam passing through crystal. However, it is well-known that a beam current density required for lasing is extremely high in X-ray spectral range for any radiation mechanisms and it is very important to find a way to lower its magnitude. The application of three-dimensional distributed feedback formed by dynamical diffraction of emitted photons permitted to reduce starting beam current density 10{sup 2}-10{sup 4} times up to 10{sup 9}. One of ways to lower the starting current is the formation of multi-wave distributed feedback the another one is the application of external reflectors. The thing is that lasing regime was shown to be produced at frequencies in the vicinity of degeneration point for roots of dispersion equation describing radiation modes excited in an active medium (crystal plus particle beam). Unfortunately, in case of parametric quasi-Cherenkov FEL this region coincides with the region of strong self-absorption of radiation inside a crystal. That fact, obviously, increases the starting beam current. In this report we have shown that the application of external Bragg reflectors gives the possibility to lower radiation self-absorption inside a crystal by modifying radiation modes excited in the active medium under consideration. The corresponding dispersion equation and the expression for excited modes are derived. The generation equation determining starting conditions for lasing is obtained. Using these expressions we have shown that the application of external Bragg reflectors permits to reduce starting beam current density more than 10 times.

  14. Magnetic Activity Analysis for a Sample of G-type Main Sequence Kepler Targets

    NASA Astrophysics Data System (ADS)

    Mehrabi, Ahmad; He, Han; Khosroshahi, Habib

    2017-01-01

    The variation of a stellar light curve owing to rotational modulation by magnetic features (starspots and faculae) on the star’s surface can be used to investigate the magnetic properties of the host star. In this paper, we use the periodicity and magnitude of the light-curve variation as two proxies to study the stellar magnetic properties for a large sample of G-type main sequence Kepler targets, for which the rotation periods were recently determined. By analyzing the correlation between the two magnetic proxies, it is found that: (1) the two proxies are positively correlated for most of the stars in our sample, and the percentages of negative, zero, and positive correlations are 4.27%, 6.81%, and 88.91%, respectively; (2) negative correlation stars cannot have a large magnitude of light-curve variation; and (3) with the increase of rotation period, the relative number of positive correlation stars decreases and the negative correlation one increases. These results indicate that stars with shorter rotation period tend to have positive correlation between the two proxies, and a good portion of the positive correlation stars have a larger magnitude of light-curve variation (and hence more intense magnetic activities) than negative correlation stars.

  15. Silicon reflectors for external cavity lasers based on ring resonators

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Li, Xia; Jin, Hao; Yu, Hui; Yang, Jianyi; Jiang, Xiaoqing

    2017-01-01

    We propose and experimentally investigate types of silicon ring reflectors on Silicon-On-Insulator (SOI) platform. These reflectors are used for realizing the silicon hybrid external cavity lasers. A suspended edge coupler is used to connect the reflective semiconductor optical amplifier (RSOA) chip and the reflectors. The properties of the reflectors and the hybrid external cavity lasers with these reflectors are illustrated. The experimental results show that all of those reflectors have a high reflectivity and the highest reflectivity can up to be 95%. The lowest insertion loss can be as low as 0.4 dB. The output power of the hybrid external cavity lasers with these reflectors can reach mW magnitude and the highest output power is 6.1 mW. Over 30 dB side mode suppression ratio is obtained.

  16. Multi-Band Frequency-Selective Microwave Reflectors

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao

    1995-01-01

    Double-loop patch and slot elements used in two different frequency-multiplexing designs. Array of double-round-loop conductive patches highly reflective at frequencies around 33 GHz (in Ka band). Array of double-square loop slots in conductive plane highly transmissive in S and Ku bands and highly reflective in X band. These frequency-selective reflectors closely related to several previous articles in NASA Tech Briefs, including "Frequency-Selective Microwave Reflectors" (NPO-18701), "Improved Dichroic Microwave Reflector" (NPO-18664), "Double-Square-Loop Dichroic Microwave Reflector" (NPO-18676), "Triband Circular-Loop Dichroic Microwave Reflector" (NPO-18714), "Making Curved Frequency-Selective Microwave Reflectors" (NPO-18755), "More Circular-Loop Dichroic Microwave Reflectors" (NPO-18940).

  17. Theory of divalent main group H2 activation: electronics and quasiclassical trajectories.

    PubMed

    Devarajan, Deepa; Doubleday, Charles E; Ess, Daniel H

    2013-08-05

    Density functional theory (DFT), absolutely localized molecular orbital (ALMO) analysis, and quasiclassical trajectories (QCTs) were used to study the structure, barrier heights, thermodynamics, electronic properties, and dynamics of dihydrogen (H2) activation by singlet divalent main group compounds (ER2; E = C, Si, Ge). ALMO energy and charge decomposition calculations reveal that in the transition state CR2 acts as an ambiphile toward H2 because of equal forward-bonding and back-bonding orbital stabilization while SiR2 and GeR2 act as nucleophiles with dominant orbital energy stabilization arising from ER2 to H2 donation. Frontier molecular orbital (FMO) energy gaps do not provide a reasonable estimate of energy stabilization gained between the ER2 and H2 in the transition state or an accurate description of the nucleophilic versus electrophilic character because of electron repulsion and orbital overlap influences that are neglected. In CR2 transition states, forward-bonding and back-bonding are maximized in the nonleast motion geometry. In contrast, SiR2/GeR2 transition states have side-on geometries to avoid electron-electron repulsion. Electron repulsion, rather than orbital interactions, also determines the relative barrier heights of CR2 versus SiR2/GeR2 reactions. Examination of barrier heights and reaction energies shows a clear kinetic-thermodynamic relationship for ER2 activation of H2. A computational survey of R groups on ER2 divalent atom centers was performed to explore the possibility for H2 activation to occur with a low barrier and thermodynamically reversible. QCTs show that dihydrogen approach and reaction with CR2 may involve geometries significantly different than the static transition-state structure. In contrast, trajectories for dihydrogen addition to SiR2 involve geometries close to the side-on approach suggested by the static transition-state structure. QCTs also demonstrate that addition of H2 to CR2 and SiR2 is dynamically concerted

  18. Iterative alignment of reflector segments using a laser tracker

    NASA Astrophysics Data System (ADS)

    Cabrera Cuevas, Lizeth; Lucero Alvarez, Maribel; Leon-Huerta, Andrea; Hernandez Rios, Emilio; Hernandez Lázaro, Josefina; Tzile Torres, Carlos; Castro Santos, David; Gale, David M.; Wilson, Grant; Narayanan, Gopal; Smith, David R.

    2013-04-01

    The Large Millimeter Telescope (LMT) is a 50m diameter millimetre-wave radio telescope situated on the summit of Sierra Negra, Puebla, at an altitude of 4600 meters. The reflector surface of the LMT currently employs84 segments arranged in three annular rings. Each segment is comprised of 8 precision composite subpanels located on five threaded adjusters. During the current primary surface refurbishment, individual segments are aligned in the telescope basement using a laser tracker. This allows increased spatial resolution in shorter timescales, resulting in the opportunity for improved logistics and increased alignment precision. To perform segment alignment an iterative process is carried out whereby the surface is measured and subpanel deformations are corrected with the goal of 40 microns RMS. In practice we have been able to achieve RMS errors of almost 20 microns, with 35 microns typical. The number of iterations varies from around ten to over 20, depending mainly on the behaviour of the mechanical adjusters that support the individual subpanels. Cross marks scribed on the reflector surface are used as fiducials, because their positions on the paraboloid are well known. Measurement data is processed using a robust curve fitting algorithm which provides a map of the surface showing the subpanel deviations. From this map the required subpanel adjuster movements are calculated allowing surface improvement in a stepwise manner.

  19. Compensation for Primary Reflector Wavefront Error

    NASA Technical Reports Server (NTRS)

    Meinel, A. B. (Inventor); Meinel, M. P. (Inventor); Stacy, J. E. (Inventor)

    1986-01-01

    The object of the invention is to compensate for errors in a large telescope primary reflector by making certain compensating deviations in a smaller, auxiliary reflector of the telescope. At least one intermediate element forms an image of the primary surface onto the secondary surface, so each point on the secondary surface corresponds to a point on the primary surface. The secondary surface is formed with a deviation from an ideal secondary surface, with the piston distance of each point on the actual secondary surface equal to the piston distance of a corresponding piston on the actual primary surface from the ideal primary surface. It is found that this results in electromagnetic (e.g., light) rays which strike a deviating area of the actual primary surface being brought to the same focus as if the actual primary surface did not have a diviation from an ideal primary surface.

  20. Contour mode resonators with acoustic reflectors

    DOEpatents

    Olsson, Roy H.; Fleming, James G.; Tuck, Melanie R.

    2008-06-10

    A microelectromechanical (MEM) resonator is disclosed which has a linear or ring-shaped acoustic resonator suspended above a substrate by an acoustic reflector. The acoustic resonator can be formed with a piezoelectric material (e.g. aluminum nitride, zinc oxide or PZT), or using an electrostatically-actuated material. The acoustic reflector (also termed an acoustic mirror) uses alternating sections of a relatively low acoustic impedance Z.sub.L material and a relatively high acoustic impedance Z.sub.H material to isolate the acoustic resonator from the substrate. The MEM resonator, which can be formed on a silicon substrate with conventional CMOS circuitry, has applications for forming oscillators, rf filters, and acoustic sensors.

  1. Support trusses for large precision segmented reflectors: Preliminary design and analysis

    NASA Technical Reports Server (NTRS)

    Collins, Timothy J.; Fichter, W. B.

    1989-01-01

    Precision Segmented Reflector (PSR) technology is currently being developed for a range of future applications such as the Large Deployable Reflector. The structures activities at NASA-Langley are outlined in support of the PSR program. Design concepts are explored for erectable and deployable support structures which are envisioned to be the backbone of these precision reflectors. Important functional requirements for the support trusses related to stiffness, mass, and surface accuracy are reviewed. Proposed geometries for these structures and factors motivating the erectable and deployable designs are discussed. Analytical results related to stiffness, dynamic behavior, and surface accuracy are presented and considered in light of the functional requirements. Results are included for both a 4-meter-diameter prototype support truss which is currently being designed as the Test Bed for the PSR technology development program, and for two 20-meter support structures.

  2. 77 FR 68151 - Agency Information Collection Activities; Submission for OMB Review; Comment Request: Main Fan...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ...: Main Fan Operation and Inspection (I-A, II-A, III, and V-A Mines) ACTION: Notice. SUMMARY: The... information collection request (ICR) titled, ``Main Fan Operation and Inspection (I-A, II-A, III, and V-A..._PUBLIC@dol.gov . Authority: 44 U.S.C. 3507(a)(1)(D). SUPPLEMENTARY INFORMATION: Potentially...

  3. Isogrid Membranes for Precise, Singly Curved Reflectors

    NASA Technical Reports Server (NTRS)

    Fang, Houfei; Lou, Michael

    2005-01-01

    A new type of composite material has been proposed for membranes that would constitute the reflective surfaces of planned lightweight, single-curvature (e.g., parabolic cylindrical) reflectors for some radar and radio-communication systems. The proposed composite materials would consist of polyimide membranes containing embedded grids of highstrength (e.g., carbon) fibers. The purpose of the fiber reinforcements, as explained in more detail below, is to prevent wrinkling or rippling of the membrane.

  4. Simulation of parabolic reflectors for ultraviolet phototherapy

    NASA Astrophysics Data System (ADS)

    Grimes, David Robert

    2016-08-01

    Ultraviolet (UVR) phototherapy is widely used to treat an array of skin conditions, including psoriasis, eczema and vitiligo. For such interventions, a quantified dose is vital if the treatment is to be both biologically effective and to avoid the detrimental effects of over-dosing. As dose is absorbed at surface level, the orientation of patient site with respect to the UVR lamps modulates effective dose. Previous investigations have modelled this behaviour, and examined the impact of shaped anodized aluminium reflectors typically placed around lamps in phototherapy cabins. These mirrors are effective but tend to yield complex patterns of reflection around the cabin which can result in substantial dose inhomogeneity. There has been some speculation over whether using the reflective property of parabolic mirrors might improve dose delivery or homogeneity through the treatment cabin. In this work, the effects of parabolic mirrors are simulated and compared with standard shaped mirrors. Simulation results strongly suggest that parabolic reflectors reduce total irradiance relative to standard shaped reflectors, and have a negligible impact on dose homogeneity.

  5. Analysis of Reflector Antennas in Radio Telescopes

    NASA Astrophysics Data System (ADS)

    Yeap, K. H.; Loh, M. C.; Tham, C. Y.; Yiam, C. Y.; Yeong, K. C.; Lai, K. C.

    2016-11-01

    We present an analysis on the performance of the Cassegrain and Gregorian on-axis, off-axis and offset antennas. In our study, we have adopted the design parameters for the Cassegrain configuration used in the Atacama Large Millimeter Array (ALMA) project. Modifications on the original parameters are made so as to meet the design requirement for the off-axis and offset configurations. To reduce spillover loss in the offset antennas, we have adjusted the angle between the axis of the primary reflector and that of the sub-reflector, so that the feed horn is placed right next to the edge of the primary reflector. This is to allow the offset antennas to receive the highest power at the feed horn. The results obtained from the physical optics simulation show that the radiation characteristics of both Cassegrain and Gregorian antennas are similar. The offset designs exhibit the best performance, followed by the on-axis, and, finally, the off-axis designs. Our analysis also shows that the performance of both offset Cassegrain and Gregorian antennas are comparable to each other.

  6. Vacuum deposited polymer/silver reflector material

    SciTech Connect

    Affinito, J.; Martin, P.; Gross, M.; Bennett, W.

    1994-07-01

    Weatherable, low cost, front surface, solar reflectors on flexible substrates would be highly desirable for lamination to solar concentrator panels. The method to be described in this paper may permit such reflector material to be fabricated for less than 50 cents per square foot. Vacuum deposited Polymer/Silver/Polymer reflectors and Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates. Reflectivities were measured in the wavelength range from .4 {mu}m to .8 {mu}m. It is hoped that a low cost substrate can be used with the substrate laminated to the concentrator and the weatherable acrylic polymer coating facing the sun. This technique should be capable of deposition line speeds approaching 1500 linear feet/minute. Central to this technique is a new vacuum deposition process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process - for Polymer Multi-Layer.

  7. Chemical Effect of Dry and Wet Cleaning of the Ru Protective Layer of the Extreme ultraviolet (EUV) Lithography Reflector

    SciTech Connect

    Belau, Leonid; Park, Jeong Y.; Liang, Ted; Seo, Hyungtak; Somorjai, Gabor A.

    2009-04-10

    The authors report the chemical influence of cleaning of the Ru capping layer on the extreme ultraviolet (EUV) reflector surface. The cleaning of EUV reflector to remove the contamination particles has two requirements: to prevent corrosion and etching of the reflector surface and to maintain the reflectivity functionality of the reflector after the corrosive cleaning processes. Two main approaches for EUV reflector cleaning, wet chemical treatments [sulfuric acid and hydrogen peroxide mixture (SPM), ozonated water, and ozonated hydrogen peroxide] and dry cleaning (oxygen plasma and UV/ozone treatment), were tested. The changes in surface morphology and roughness were characterized using scanning electron microscopy and atomic force microscopy, while the surface etching and change of oxidation states were probed with x-ray photoelectron spectroscopy. Significant surface oxidation of the Ru capping layer was observed after oxygen plasma and UV/ozone treatment, while the oxidation is unnoticeable after SPM treatment. Based on these surface studies, the authors found that SPM treatment exhibits the minimal corrosive interactions with Ru capping layer. They address the molecular mechanism of corrosive gas and liquid-phase chemical interaction with the surface of Ru capping layer on the EUV reflector.

  8. Characterising Seismicity at Alutu, an Actively Deforming Volcano in the Main Ethiopian Rift

    NASA Astrophysics Data System (ADS)

    Wilks, M.; Nowacki, A.; Kendall, J. M.; Wookey, J. M.; Biggs, J.; Bastow, I. D.; Ayele, A.; Bedada, T.

    2013-12-01

    The Main Ethiopian Rift (MER) provides a unique example of the tectonic and volcanic processes occuring during the transition from continental rifting to oceanic spreading. Situated 100 km south of Addis Ababa along the eastern rift margin, Alutu is a silicic stratovolcano that geodetic measurements (InSAR and GPS) have shown is actively deforming. Though the volcano has received relatively little scientific attention it is also a site of economic significance as a geothermal power plant resides within the caldera. As part of ARGOS (Alutu Research Geophysical ObservationS), a multi-disciplinary project aiming to investigate the magmatic and hydrothermal processes occuring at Alutu, a seismic network of 12 broadband seismometers was deployed in January 2012. Other components of ARGOS include InSAR, GPS, geologic mapping and magnetotellurics. From the seismic dataset, P- and S-wave arrivals across the array were manually picked and used to locate events using a non-linear earthquake location algorithm (NonLinLoc) and a predefined 1D velocity model. Perturbations were later applied to this velocity model to investigate the sensitivity of the locations and evaluate the true uncertainties of the solutions. Over 1000 events were successfully located during 2012, where picks were possible at 4 or more stations. Seismicity clusters at both shallow depths (z<2 km) beneath the caldera and at deeper depths of 5-15 km. There is a significant increase in seismicity during the rainy months, suggesting the shallow events may be related to the hydrothermal system. We interpret the deeper events as being magmatic in origin. Events are also located along the eastern border faults that bound the outer edges of the MER and highlights that seismicity arises concurrently via tectonic processes. An adapted version of Richter's original local magnitude scale (ML) to account for attenuation within the MER (Keir et al., 2006) was then used to compute magnitudes for the best located events

  9. Nisin as a Food Preservative: Part 1: Physicochemical Properties, Antimicrobial Activity, and Main Uses.

    PubMed

    Gharsallaoui, Adem; Oulahal, Nadia; Joly, Catherine; Degraeve, Pascal

    2016-06-10

    Nisin is a natural preservative for many food products. This bacteriocin is mainly used in dairy and meat products. Nisin inhibits pathogenic food borne bacteria such as Listeria monocytogenes and many other Gram-positive food spoilage microorganisms. Nisin can be used alone or in combination with other preservatives or also with several physical treatments. This paper reviews physicochemical and biological properties of nisin, the main factors affecting its antimicrobial effectiveness, and its food applications as an additive directly incorporated into food matrices.

  10. Final Report: Main Group Element Chemistry in Service of Hydrogen Storage and Activation

    SciTech Connect

    David A. Dixon; Anthony J. Arduengo, III

    2010-09-30

    goal was met in terms of reducing the number of costly experiments and helping to focus the experimental effort on the potentially optimal targets. We have used computational chemistry approaches to predict the thermodynamic properties of a wide range of compounds containing boron, nitrogen, hydrogen, and other elements as appropriate including carbon. These calculations were done in most cases with high level molecular orbital theory methods that have small error bars on the order of ± 1 to 2 kcal/mol. The results were used to benchmark more approximate methods such as density functional theory for larger systems and for database development. We predicted reliable thermodynamics for thousands of compounds for release and regeneration schemes to aid/guide materials design and process design and simulation. These are the first reliable computed values for these compounds and for many represent the only available values. Overall, the computational results have provided us with new insights into the chemistry of main group and organic-base chemical hydrogen systems from the release of hydrogen to the regeneration of spent fuel. A number of experimental accomplishments were also made in this project. The experimental work on hydrogen storage materials centered on activated polarized σ- or π-bonded frameworks that hold the potential for ready dihydrogen activation, uptake, and eventually release. To this end, a large number of non-traditional valence systems including carbenes, cyanocarbons, and C-B and and B-N systems were synthesized and examined. During the course of these studies an important lead arose from the novel valency of a class of stable organic singlet bi-radical systems. A synthetic strategy to an “endless” hydrogen storage polymer has been developed based on our cyanocarbon chemistry. A key issue with the synthetic efforts was being able to link the kinetics of release with the size of the substituents as it was difficult to develop a low molecular

  11. Redefining Medlicott-Wadia's main boundary fault from Jhelum to Yamuna: An active fault strand of the main boundary thrust in northwest Himalaya

    NASA Astrophysics Data System (ADS)

    Thakur, V. C.; Jayangondaperumal, R.; Malik, M. A.

    2010-06-01

    The MBT demarcates a tectonic boundary between the Tertiary Sub Himalaya and the pre-Tertiary Lesser Himalaya. South of the MBT, another tectonically important fault extends from Muzaffarabad and Riasi in Jammu-Kashmir to Bilaspur and Nahan in Himachal. Medlicott and Wadia had designated this fault the Main Boundary Fault (MBF) in Simla Hills and Jammu region respectively. In between these two areas, later workers gave local-area names to the MBF as the Riasi Thrust in Jammu, Palampur Thrust in Kangra, Bilaspur Thrust in Simla Hills and Nahan Thrust in Sirmur. We have reviewed and established the tectonostratigraphic framework and physical continuity of the lower Tertiary belt and the MBF. The lower Tertiary belt, lying south of the MBT, has characteristic tectonostratigraphic setting with discontinuous bodies of stromatolite-bearing Proterozoic limestone overlain with depositional contact by the Paleocene-lower part Middle Eocene marine Subathu/Patala formation which in turn overlain by the Upper Oligocene-Lower Miocene non-marine Dharamsala/Murree Formation. To avoid confusion with the MBT, we designate collectively the MBF and related faults as the Medlicott-Wadia Thrust (MWT). The MWT extends east of Hazara-Kashmir syntaxis to river Yamuna, covering a distance of ˜ 700 km. Further east of Yamuna, the lower Tertiary belt pinches out and the MWT merges with the sensuo-stricto MBT. The Proterozoic limestone represents the basement over which the lower Tertiary sediments were deposited. The limestone basement with its cover was detached by the MWT, exhuming to the surface and thrusting over largely the Siwalik group. The reactivated Balakot-Bagh Fault, causative fault for the 2005 Kashmir earthquake, extends southeast with right-step to the Riasi Thrust. The Riasi Thrust shows evidence of reactivation and active tectonic activity in Jammu region. It extends further east to the Palampur Thrust in Kangra reentrant, which lies within the 1905 Kangra earthquake

  12. Properties of wideband resonant reflectors under fully conical light incidence

    NASA Astrophysics Data System (ADS)

    Ko, Yeong Hwan; Niraula, Manoj; Lee, Kyu Jin; Magnusson, Robert

    2016-03-01

    Applying numerical modeling coupled with experiments, we investigate the properties of wideband resonant reflectors under fully conical light incidence. We show that the wave vectors pertinent to resonant first-order diffraction under fully conical mounting vary less with incident angle than those associated with reflectors in classical mounting. Therefore, as the evanescent diffracted waves drive the leaky modes responsible for the resonance effects, fully-conical mounting imbues reflectors with larger angular tolerance than their classical counterparts. We quantify the angular-spectral performance of representative resonant wideband reflectors in conic and classic mounts by numerical calculations with improved spectra found for fully conic incidence. Moreover, these predictions are verified experimentally for wideband reflectors fashioned in crystalline and amorphous silicon in distinct spectral regions spanning the 1200-1600-nm and 1600-2400-nm spectral bands. These results will be useful in various applications demanding wideband reflectors that are efficient and materially sparse.

  13. A new approach for shaping of dual-reflector antennas

    NASA Technical Reports Server (NTRS)

    Lee, Teh-Hong; Burnside, W. D.; Rudduck, Roger C.

    1987-01-01

    The shaping of 2-D dual-reflector antenna systems to generate a prescribed distribution with uniform phase at the aperture of the second reflector is examined. This method is based on the geometrical nature of Cassegrain and Gregorian dual-reflector antennas. The method of syntheses satisfies the principles of geometrical optics which are the foundations of dual-reflector designs. Instead of setting up differential equations or heuristically designing the subreflector, a set of algebraic equations is formulated and solved numerically to obtain the desired surfaces. The caustics of the reflected rays from the subreflector can be obtained and examined. Several examples of 2-D dual-reflector shaping are shown to validate the study. Geometrical optics and physical optics are used to calculate the scattered fields from the reflectors.

  14. Is spinal excitability of the triceps surae mainly affected by muscle activity or body position?

    PubMed

    Cattagni, T; Martin, A; Scaglioni, G

    2014-06-15

    The aim of this study was to determine how muscle activity and body orientation contribute to the triceps surae spinal transmission modulation, when moving from a sitting to a standing position. Maximal Hoffmann-reflex (Hmax) and motor potential (Mmax) were evoked in the soleus (SOL), medial and lateral gastrocnemius in 10 male subjects and in three conditions, passive sitting, active sitting and upright standing, with the same SOL activity in active sitting and upright standing. Moreover volitional wave (V) was evoked in the two active conditions (i.e., active sitting and upright standing). The results showed that SOL Hmax/Mmax was lower in active sitting than in passive sitting, while for the gastrocnemii it was not significantly altered. For the three plantar flexors, Hmax/Mmax was lower in upright standing than in active sitting, whereas V/Mmax was not modulated. SOL H-reflex is therefore affected by the increase in muscle activity and change in body orientation, while, in the gastrocnemii, it was only affected by a change in posture. In conclusion, passing from a sitting to a standing position affects the Hmax/Mmax of the whole triceps surae, but the mechanisms responsible for this change differ among the synergist muscles. The V/Mmax does not change when upright stance is assumed. This means that the increased inhibitory activity in orthostatic position is compensated by an increased excitatory inflow to the α-motoneurons of central and/or peripheral origin.

  15. Wideband QAMC reflector's antenna for low profile applications

    NASA Astrophysics Data System (ADS)

    Grelier, M.; Jousset, M.; Mallégol, S.; Lepage, A. C.; Begaud, X.; LeMener, J. M.

    2011-06-01

    A wideband reflector's antenna based on quasi-artificial magnetic conductor is proposed. To validate the design, an Archimedean spiral has been backed to this new reflector. In comparison to classical solution using absorbent material, the prototype presents a very low thickness of λ/15 at the lowest operating frequency and an improved gain over a 2.4:1 bandwidth. The whole methodology to design this reflector can be applied to other wideband antennas.

  16. Controlled-Shape, Ultrasonic-Angle-Beam Standard Reflector

    NASA Technical Reports Server (NTRS)

    Berry, J., Robertf.

    1986-01-01

    New ultrasonic angle-beam standard reflector uses impression of letter "l" steel-die stamp. NDE techniques and standard reflector apply to use of pulse-echo-type ultrasonic equipment for inspection of wrought metals including forgings and forging stock; rolled billet, bar or plate; and extruded bar, tube, and shapes. "l" reference standard reflector affords advantages of easy insertion in inspected item using common hand-tools and greatly reduced implementation time through elimination of machining operations.

  17. The DART Cylindrical, Infrared, 1 Meter Membrane Reflector

    NASA Technical Reports Server (NTRS)

    Morgan, Rhonda M.; Agnes, Greg S.; Barber, Dan; Dooley, Jennifer; Dragovan, Mark; Hatheway, Al E.; Marcin, Marty

    2004-01-01

    The Dual Anamorphic Reflector Telescopes (DART) is an architecture for large aperture space telescopes that enables the use of membranes. A membrane can be readily shaped in one direction of curvature using a combination of boundary control and tensioning, yielding a cylindrical reflector. Two cylindrical reflectors (orthogonal and confocal) comprise the 'primary mirror' of the telescope system. The aperture is completely unobstructed and ideal for infrared and high contrast observations.

  18. Magnetron sputtering in rigid optical solar reflectors production

    NASA Astrophysics Data System (ADS)

    Asainov, O. Kh; Bainov, D. D.; Krivobokov, V. P.; Sidelev, D. V.

    2016-07-01

    Magnetron sputtering was applied to meet the growing need for glass optical solar reflectors. This plasma method provided more uniform deposition of the silver based coating on glass substrates resulted in decrease of defective reflectors fraction down to 5%. For instance, such parameter of resistive evaporation was of 30%. Silver film adhesion to glass substrate was enhanced with indium tin oxide sublayer. Sunlight absorption coefficient of these rigid reflectors was 0.081-0.083.

  19. Testing the figure of parabolic reflectors for solar concentrators.

    PubMed

    Bodenheimer, J S; Eisenberg, N P; Gur, J

    1982-12-15

    A novel method for testing the optical quality of large parabolic solar concentrators is presented, based on autocollimation. An optical system continuously scans the reflector along a fixed reference axis. At each position along the axis, the spread function is obtained. Analysis of the location, width, and intensity changes of this function gives quantitative information about the reflector's defects. A figure of merit describing the performance of parabolic trough reflectors is proposed.

  20. Velocity characteristics of reflectors in solar tower systems

    NASA Astrophysics Data System (ADS)

    Aparisi, R. R.; Tepliakov, D. I.; Khantsis, B. G.

    An analysis is presented of the velocities of azimuthal and zenithal rotations of reflectors in solar tower systems in relation to reflector arrangement, geographic latitude, and season of the year. Two methods are used in the analysis: (1) the direct calculation of heliostat rotation velocity at successive moments of time; and (2) a generalized representation of reflector velocity fields. Research and engineering applications of the calculations are discussed.

  1. Designs for the ATDRSS tri-band reflector antenna

    NASA Technical Reports Server (NTRS)

    Lee, Shung-Wu; Zimmerman, Martin L.; Fujikawa, Gene; Sharp, G. Richard

    1991-01-01

    Two approaches to design a tri-band reflector antenna for the Advanced TDRSS are examined. Two reflector antenna configurations utilizing frequency selective surfaces for operation in three frequency bands, S, Ku, and Ka, are proposed. Far-field patterns and the antenna feed losses were computed for each configuration. An offset-fed single reflector antenna configuration was adapted for conceptual spacecraft design. CADAM drawings were completed and a 1/13th scale model of the spacecraft was constructed.

  2. The Main Sequence of Explosive Solar Active Regions: Discovery and Interpretation

    DTIC Science & Technology

    2009-01-01

    from equilibrium between input of free energy to an explosive active region’s magnetic field in the chromosphere and corona by contortion of the field...coronal mass ejections (CMEs) – Sun: flares 1. INTRODUCTION For an active region’s chromospheric and coronal magnetic field to be able to...reason for this trend is that in the smaller active regions near the front the maximum rate of buildup of free energy in the field in the chromosphere

  3. Ellipsoidal reflector design of the LED vehicle projector type headlamp

    NASA Astrophysics Data System (ADS)

    Ying, Shang-Ping; Lyu, Jhen-Cyun

    2016-09-01

    In this study, the design of the projector type headlamp using LEDs with different structure parameters is proposed. The ellipsoidal reflector with different major and minor axis would contribute different aperture and focal lengths of the ellipsoidal reflector, and then collimate the light to the converging lens. With specific converging lens and metal-based baffle plate in the projector type headlamp system, we systematical analysis of the ellipsoidal reflector in the projector type headlamp. The systematical analysis of the ellipsoidal reflector can be a reference to design a projector type headlamp with compact size and high photometry performance.

  4. POMESH - DIFFRACTION ANALYSIS OF REFLECTOR ANTENNAS

    NASA Technical Reports Server (NTRS)

    Hodges, R. E.

    1994-01-01

    POMESH is a computer program capable of predicting the performance of reflector antennas. Both far field pattern and gain calculations are performed using the Physical Optics (PO) approximation of the equivalent surface currents. POMESH is primarily intended for relatively small reflectors. It is useful in situations where the surface is described by irregular data that must be interpolated and for cases where the surface derivatives are not known. This method is flexible and robust and also supports near field calculations. Because of the near field computation ability, this computational engine is quite useful for subreflector computations. The program is constructed in a highly modular form so that it may be readily adapted to perform tasks other than the one that is explicitly described here. Since the computationally intensive portions of the algorithm are simple loops, the program can be easily adapted to take advantage of vector processor and parallel architectures. In POMESH the reflector is represented as a piecewise planar surface comprised of triangular regions known as facets. A uniform physical optics (PO) current is assumed to exist on each triangular facet. Then, the PO integral on a facet is approximated by the product of the PO current value at the center and the area of the triangle. In this way, the PO integral over the reflector surface is reduced to a summation of the contribution from each triangular facet. The source horn, or feed, that illuminates the subreflector is approximated by a linear combination of plane patterns. POMESH contains three polarization pattern definitions for the feed; a linear x-polarized element, linear y-polarized element, and a circular polarized element. If a more general feed pattern is required, it is a simple matter to replace the subroutine that implements the pattern definitions. POMESH obtains information necessary to specify the coordinate systems, location of other data files, and parameters of the desired

  5. The main constituents of Tulipa systola Stapf. roots and flowers; their antioxidant activities.

    PubMed

    Ibrahim, Mohammed Farhad; Hussain, Faiq Hama Saeed; Zanoni, Giuseppe; Vidari, Giovanni

    2016-12-28

    People living on the mountains of the Kurdistan Region, Iraq make a large use of herbs in the local traditional medicine. Among them, Tulipa systola, which grows under and between rocks, is very popular as an anti-inflammatory remedy and pain-relief. The phytochemical study of an ethanolic extract obtained from flowers and roots of Tulip (T systola Stapf.) afforded three compounds, identified as (+)-1-O-E-feruloyl-3-O-E-p-coumaroylglycerol (1), (+)-6-tuliposide A (2), and (-)-kaempferol-3-O-rutinoside (3). The significant radical scavenging and antioxidant activity of the isolated compounds were evaluated on three tests, by determining the DPPH free radical scavenging activity, the total antioxidant activity and the hydrogen peroxide scavenging activity. Tuliposide A shows potent allergenic activity.

  6. Infrared reflector based on liquid crystal polymers and its impact on thermal comfort conditions in buildings

    NASA Astrophysics Data System (ADS)

    Khandelwal, Hitesh; Roberz, Franziska; Loonen, Roel C. G. M.; Hensen, Jan L. M.; Bastiaansen, Cees W. M.; Broer, Dick J.; Debije, Michael G.; Schenning, Albert P. H. J.

    2014-10-01

    There has been a huge increase in the global demand of energy over the last few years. One of the main contributors to energy consumption in buildings, cars, greenhouses and indoor spaces is the cooling devices needed to maintain the indoor temperature at comfortable levels. To reduce the energy used by cooling devices, we need improved light control in transparent building elements, such as windows. Infrared (IR) reflectors applied to the windows for rejection of infrared light would be very attractive, especially if they do not affect light in the visible region. A method to selectively and precisely control infrared transmission is via the use of cholesteric liquid crystal (Ch-LC) polymer reflectors. Ch-LCs, also known as chiral-nematic LCs, reflect circularly polarized light as a result of their self-organizing molecular helices. The pitch of the helix in these networks determines the wavelength of reflection. In contrast to existing alternatives, they are characterized by a very sharp cut-off between the transmissive and the reflective state enabling exact tailoring of the heat reflection. In this article we have focused on fabrication of infrared reflectors using Ch-LCs and a computational model was used to predict the energy savings of this IR-reflector in an office building in Abu Dhabi which indicated that 6 % energy savings can be realized.

  7. Design and rigorous analysis of generalized axially- symmetric dual-reflector antennas

    NASA Astrophysics Data System (ADS)

    Moreira, Fernando J. S.

    1997-10-01

    The development of reflector antennas is continuously driven by ever increasing performance requirements, creating a demand for improved design and analysis tools. Ideally, the antenna synthesis should rely on general closed-form design equations (to establish the initial geometry and performance), as well as on accurate analysis techniques (to tune up the antenna performance by accounting for all pertinent electrical effects). Driven by these motivations, this dissertation provides the required formulation for the rigorous (in a numerical sense) analysis of axially-symmetric dual-reflector antennas and for their effective design. The rigorous analysis is performed using integral-equation techniques, which permit the inclusion of all relevant antenna components (i.e., reflector surfaces and feed structure), with the exception of the supporting struts and radomes. These techniques allow the electrical performance of a designed antenna to be accurately determined, hence minimizing the use of hardware models. The design portion starts with a unified investigation of generalized classical axially-symmetric dual-reflector antennas- conic-section generated configurations that minimize the main-reflector scattering towards the subreflector while providing a uniform-phase aperture illumination. It is shown that all possible configurations can be grouped in four basic categories. Using Geometrical Optics principles, useful closed-form design expressions are obtained, allowing a straightforward determination of the initial geometry and its upper-bound high-frequency performance. The improvement of the antenna radiation characteristics through the reflector shaping is also explored. An amplitude distribution is proposed for the shaped-antenna aperture field (with constant phase), providing high efficiency while controlling the sidelobe envelope. The diffraction and spillover effects are also investigated using Geometrical Theory of Diffraction, yielding useful formulas and

  8. Antibacterial and Anti-Inflammatory Activities of Physalis Alkekengi var. franchetii and Its Main Constituents

    PubMed Central

    Shu, Zunpeng; Xing, Na; Wang, Qiuhong; Li, Xinli; Xu, Bingqing; Li, Zhenyu; Kuang, Haixue

    2016-01-01

    This study was designed to determine whether the 50% EtOH fraction from AB-8 macroporous resin fractionation of a 70% EtOH extract of P. Alkekengi (50-EFP) has antibacterial and/or anti-inflammatory activity both in vivo and in vitro and to investigate the mechanism of 50-EFP anti-inflammatory activity. Additionally, this study sought to define the chemical composition of 50-EFP. Results indicated that 50-EFP showed significant antibacterial activity in vitro and efficacy in vivo. Moreover, 50-EFP significantly reduced nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), interleukin 1 (IL-1), and interleukin 6 (IL-6) production in lipopolysaccharide- (LPS-) stimulated THP-1 cells. Nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) (examined at the protein level) in THP-1 cells were suppressed by 50-EFP, which inhibited nuclear translocation of p65. Consistent with this anti-inflammatory activity in vitro, 50-EFP reduced inflammation in both animal models. Finally, seventeen compounds (8 physalins and 9 flavones) were isolated as major components of 50-EFP. Our data demonstrate that 50-EFP has antibacterial and anti-inflammatory activities both in vitro and in vivo. The anti-inflammatory effect appears to occur, at least in part, through the inhibition of nuclear translocation of p65. Moreover, physalins and flavones are probably the active components in 50-EFP that exert antibacterial and anti-inflammatory activities. PMID:27057196

  9. Essential oil from Chenopodium ambrosioides and main components: activity against Leishmania, their mitochondria and other microorganisms.

    PubMed

    Monzote, Lianet; García, Marley; Pastor, Jacinta; Gil, Lizette; Scull, Ramón; Maes, Louis; Cos, Paul; Gille, Lars

    2014-01-01

    Chenopodium ambrosioides is an aromatic herb used by native people to treat parasitic diseases. The aim of this work is to compare the in vitro anti-leishmanial activity of the essential oil (EO) from C. ambrosioides and its major components (ascaridole, carvacrol and caryophyllene oxide) and study their mechanism of action and activity against a panel of microorganism. Antileishmanial activity and cytotoxicity of the EO and major components was study. In addition, experiments to elucidate the mechanism of action were perform and activities against other microorganisms (bacteria, fungi and protozoa) were evaluate. All products were active against promastigote and amastigote forms of Leishmania. Ascaridole exhibited the better antileishmanial activity and the EO the highest selectivity index. The exploration of the mechanism suggests that the products cause a breakdown of mitochondrial membrane potential and a modification of redox indexes. Only EO showed antiprotozoal effect against Plasmodium falciparum and Trypanosoma brucei; while no activity against bacteria and fungi was observed. Our results demonstrate the potentialities of EO in cellular and molecular system, which could be consider in future studies to develop new antileishmanial drugs with a wide anti-parasitic spectrum.

  10. Free-flying solar reflector spacecraft

    NASA Technical Reports Server (NTRS)

    Hedgepeth, J. M.

    1981-01-01

    Results of investigations of requirements and design concepts for large solar-reflecting spacecraft are given. The emphasis is on the one kilometer diameter self contained spacecraft that can be packaged and launched in the space shuttle. The configuration consists of a compression rim stabilized by stays coming from each end of the central compression hub. The stays are stowed on reels on the ends of the hub. The hub consists of two Astromasts which are deployed after launch. The reflector membrane is a two micron thick Kapton film with a vapor deposited aluminum coating.

  11. Experiences with large CFRP-radiotelescope reflectors

    NASA Astrophysics Data System (ADS)

    Muser, D.

    1991-10-01

    Since 1986 several ground based 15 m radiotelescopes with CFRP (Carbon Fiber Reinforced Plastic) structures and reflector panels are under operation in the millimeter wavelength range. A new submillimeter telescope with 10 m diameter is under manufacture. Analysis and design, manufacturing and qualification show the advantages of CFRP. While the assembled dishes have accuracies of some 50 micrometers rms the mean value of about 1000 panels was measured to 12 micrometer rms. These results show the possibilities of manufacturing large space based antennae with the required accuracies for millimeter and submillimeter operations.

  12. Bright color reflective displays with interlayer reflectors

    NASA Astrophysics Data System (ADS)

    Kitson, Stephen; Geisow, Adrian; Rudin, John; Taphouse, Tim

    2011-08-01

    A good solution to the reflective display of color has been a major challenge for the display industry, with very limited color gamuts demonstrated to date. Conventional side-by-side red, green and blue color filters waste two-thirds of incident light. The alternative of stacking cyan, magenta and yellow layers is also challenging -- a 10% loss per layer compounds to nearly 50% overall. Here we demonstrate an architecture that interleaves absorbing-to-clear shutters with matched wavelength selective reflectors. This increases color gamut by reducing losses and more cleanly separating the color channels, and gives much wider choice of electro-optic colorants.

  13. Antimicrobial activity and main chemical composition of two smoke condensates from Peganum harmala seeds.

    PubMed

    Shahverdi, Ahmad R; Monsef-Esfahani, Hamid R; Nickavar, Bahman; Bitarafan, Lila; Khodaee, Samira; Khoshakhlagh, Narges

    2005-01-01

    The smoke of Peganum harmala seeds is traditionally used in Iran as a disinfectant agent. The aim of this study was to determine the antimicrobial activity of two smoke condensates from Peganum harmala seeds. Furthermore the composition of smoke preparations was studied using gas chromatography and mass spectroscopy analysis. The most prevalent compound detected in a dichloromethane extract was harmine. Standard harmine as well as the dichloromethane extract showed antimicrobial activity against all test strains. Harmine was not detected in an n-hexane extract and we did not observe antimicrobial activity from this smoke preparation at the tested concentrations.

  14. Main determinants of physical activity levels in individuals with Parkinson's disease.

    PubMed

    Lana, Raquel de Carvalho; de Araujo, Lysandra Nogueira; Cardoso, Francisco; Rodrigues-de-Paula, Fátima

    2016-02-01

    This study analyzed the relationship between patient characteristics, factors associated with Parkinson's disease (PD), and physical activity level of individuals affected by the disease. Forty-six volunteers with mild-to-moderate idiopathic PD were assessed using sections II/III of the Unified Parkinson's Disease Rating Scale and their motor functions were classified according to the modified Hoehn and Yahr (HY) scale. Data such as age, disease duration, the Human Activity Profile (HAP), the Fatigue Severity Scale were collected. Lower limb bradykinesia and clinical subtypes of PD were defined. Two models that explained 76% of the variance of the HAP were used. The first comprised age, ability to perform activities of daily living (ADL), and the HY scale; the second comprised age, ability to perform ADL, and lower limb bradykinesia. Possible modifiable factors such as the ability to perform ADL and lower limb bradykinesia were identified as predictors of physical activity level of individuals with PD.

  15. Active phenomena in the pre-main sequence Herbig Ae star HD 163296

    NASA Technical Reports Server (NTRS)

    Catala, C.; Praderie, F.; Simon, T.; Talavera, A.; The, P. S.

    1989-01-01

    Observations by IUE of the short-term variability of the Mg II and Ca II resonance lines in the Herbig Ae star HD 163296 are presented. Evidence that these lines show a phenomenon of rotational modulation, similar to the one observed in AB Aur, another Herbig Ae star is found. The variations in the spectrum of HD 163296 are even more conspicuous than in the spectrum of AB Aur. Magnetically structured winds may thus be a widespread phenomenon among the pre-main sequence Herbig Ae/Be stars.

  16. New CPV Systems With Static Reflectors

    NASA Astrophysics Data System (ADS)

    Tripanagnostopoulos, Y.; Chemisana, D.; Rosell, J. I.; Souliotis, M.

    2010-10-01

    New designs of low concentrating photovoltaics have been studied, where static reflectors and moving absorbers that track the concentrated solar rays, aim to cost effective solar devices. These systems are based on the concept that strip absorbers can use the beam radiation and convert it to electricity, while the diffuse radiation is absorbed by flat absorbers and converted into heat. The work on these designs follow the research on the linear Fresnel lenses, which are combined with PV or PV/T absorbers and can be used not only for the conversion of solar radiation into electricity and heat but also to control the illumination and the temperature of interior building spaces. Design aspects and optical results give a figure of the optical performance of these new CPV collectors, which are based on the converged solar radiation distribution profiles for East-West orientation of parabolic trough reflectors. The concentration ratio depends on the geometry of the parabola axis and the higher values correspond to the axis towards the summer solstice. The results show that the new CPV designs can be effectively applied in buildings adapting energy demand in electricity and heat.

  17. Hybrid grating reflectors: Origin of ultrabroad stopband

    NASA Astrophysics Data System (ADS)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

    2016-04-01

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well as a weak guided mode (GM) resonance. Most of the reflected power results from the FP resonance, while the GM resonance plays a key role in achieving a reflectance close to 100% as well as broadening the stopband. An HG sample with 7 InGaAlAs quantum wells included in the cap layer has been fabricated by directly wafer-bonding a III-V cap layer onto a Si grating layer. Its reflection property has been characterized. This heterogeneously integrated HG reflector may allow for a hybrid III-V on Si laser to be thermally efficient, which has promising prospects for silicon photonics light sources and high-speed operation.

  18. Optical Reflectance Measurements for Commonly Used Reflectors

    SciTech Connect

    Janecek, Petr Martin; Moses, William

    2008-06-11

    When simulating light collection in scintillators, modeling the angular distribution of optical light reflectance from surfaces is very important. Since light reflectance is poorly understood, either purely specular or purely diffuse reflectance is generally assumed. In this paper we measure the optical reflectance distribution for eleven commonly used reflectors. A 440 nm, output power stabilized, un-polarized laser is shone onto a reflector at a fixed angle of incidence. The reflected light's angular distribution is measured by an array of silicon photodiodes. The photodiodes are movable to cover 2 pi of solid angle. The light-induced current is, through a multiplexer, read out with a digital multimeter. A LabVIEW program controls the motion of the laser and the photodiode array, the multiplexer, and the data collection. The laser can be positioned at any angle with a position accuracy of 10 arc minutes. Each photodiode subtends 6.3o, and the photodiode array can be positioned at any angle with up to 10 arc minute angular resolution. The dynamic range for the current measurements is 105:1. The measured light reflectance distribution was measured to be specular for several ESR films as well as for aluminum foil, mostly diffuse for polytetrafluoroethylene (PTFE) tape and titanium dioxide paint, and neither specular nor diffuse for Lumirror(R), Melinex(R) and Tyvek(R). Instead, a more complicated light distribution was measured for these three materials.

  19. Test progress on the electrostatic membrane reflector

    NASA Technical Reports Server (NTRS)

    Goslee, J. W.; Mihora, D. J.

    1981-01-01

    NASA is currently developing a low mass antenna which derives its reflector surface quality from the application of electrostatic forces to form a thin membrane into the desired concave reflector surface. The shuttle-deployed antenna would have a diameter of 100 m and an RMS surface smoothness of 10 to 1 mm for operation at 1 to 10 GHz. Surface quality measurements have been made on a highly deformable elastic membrane, pressurized by electrostatic forces. Included are the effects of the perimeter boundary, splicing of the membrane, the long-scale smoothness of commercial membranes, and the spatial controllability of the membrane using voltage adjustments to alter the electrostatic forces. The electrostatic membrane was found to operate well in an open-loop sense, showing a high degree of position stability and negligible power consumption in dry air. Visco-electric creep was not evident, but the polymer membrane did expand and contract considerably due to its hygroscopic expansion coefficient. A residual roughness of about 0.75 mm existed with the polymer used in these tests; this error is attributed to seams and membrane anisotropy where the material is stiffer in one direction.

  20. The polyphenol content and antioxidant activities of the main edible vegetables in northern Vietnam.

    PubMed

    Thu, Nghiem Nguyet; Sakurai, Chika; Uto, Harumi; Van Chuyen, Nguyen; Lien, Do Thi Kim; Yamamoto, Shigeru; Ohmori, Reiko; Kondo, Kazuo

    2004-06-01

    Oxidized low-density lipoprotein (LDL) is considered a risk factor in atherosclerosis, and polyphenols are the potential agents to inhibit the oxidation of LDL. We determined the polyphenol contents and the antioxidant activities of commonly consumed vegetables in Vietnam and assessed the quantity of the polyphenol intake from vegetables in the current Vietnamese diet. The polyphenol contents in 30 kinds of vegetables was determined by the Folin-Ciocalteu method. The antioxidant activities of vegetables were evaluated by measuring the oxidation of LDL and the reduction of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. In this study, some herbs and edible wild vegetables possessed high contents of polyphenols and antioxidant activities. Among green vegetables, sweet potato leaves showed both a high polyphenol content and antioxidant activity. The mean polyphenol daily intake of the Vietnamese was a 595 mg catechin equivalent. Water spinach, a kind of green vegetable, contributed the highest amount (45%) of the total polyphenol intake, followed by other green vegetables. Neither herbs nor edible wild vegetables contributed significantly to the total polyphenol intake due to their low consumption. Green vegetables are therefore considered very important sources of polyphenol intake for the Vietnamese.

  1. The Main Sources of Intersubject Variability in Neuronal Activation for Reading Aloud

    ERIC Educational Resources Information Center

    Kherif, Ferath; Josse, Goulven; Seghier, Mohamed L.; Price, Cathy J.

    2009-01-01

    The aim of this study was to find the most prominent source of intersubject variability in neuronal activation for reading familiar words aloud. To this end, we collected functional imaging data from a large sample of subjects (n = 76) with different demographic characteristics such as handedness, sex, and age, while reading. The…

  2. Antioxidant activities of Lampaya medicinalis extracts and their main chemical constituents

    PubMed Central

    2014-01-01

    Background Lampaya medicinalis Phil. (Verbenaceae) is a plant used by Aymara and Quechua ethnic groups from Northern Chile as folk medicine in the treatment and cure of various diseases. The aim of this study was to investigate the in vitro antioxidant activity, total phenols content, total flavonoids content, total antioxidant activity, reducing power, brine shrimp cytotoxicity and identify the principal chemical constituents. Methods The crude hydroethanolic extract (HEE) and its partitioned fraction: hexane (HF), dichloromethane (DF), ethyl acetate (EAF), n-butanol (BF) and soluble residual aqueous fraction (RWF) were evaluated for their antioxidant activity using different assays namely, DPPH, ABTS, FRAP, β-carotene bleaching assay. The content of total phenolics and total flavonoids were measured by Folin-Ciocalteau and by the AlCl3 colorimetric method, respectively. Reducing power was determined by phosphomolybdate and hexacyanoferrate (III) methods. Biotoxicity assays were performed on shrimps of Artemia salina. The EAF was fractionated using chromatographic methods. Results Considerable amount of phenolic and flavonoid contents were recorded in the hydroethanolic extract (HEE) and its derived fractions. Although HEE and all its derived fractions exhibited good antioxidant activities, the most distinguished radical scavenging potential was observed for ethyl acetate fraction (EAF). EAF showed the higher radical scavenging activity by DPPH (95%) and by ABTS (98%), antioxidant activity by FRAP (158.18 ± 5.79 mg equivalent Trolox/g fraction), β-carotene bleaching assay (86.8%), the highest total phenols content (101.26 ± 1.07 mg GAE/g fraction), the highest total flavonoids content (66.26 ± 3.31 μg quercetin/g fraction). The EAF extract showed an reducing power of 78% and 65% using the phosphomolybdate and hexacyanoferrate (III) assays, respectively. Four flavonoids, two p-hydroxyacetophenone derivatives and one iridoid were isolated from Lampaya

  3. Soil microbial biomass, basal respiration and enzyme activity of main forest types in the Qinling Mountains.

    PubMed

    Cheng, Fei; Peng, Xiaobang; Zhao, Peng; Yuan, Jie; Zhong, Chonggao; Cheng, Yalong; Cui, Cui; Zhang, Shuoxin

    2013-01-01

    Different forest types exert essential impacts on soil physical-chemical characteristics by dominant tree species producing diverse litters and root exudates, thereby further regulating size and activity of soil microbial communities. However, the study accuracy is usually restricted by differences in climate, soil type and forest age. Our objective is to precisely quantify soil microbial biomass, basal respiration and enzyme activity of five natural secondary forest (NSF) types with the same stand age and soil type in a small climate region and to evaluate relationship between soil microbial and physical-chemical characters. We determined soil physical-chemical indices and used the chloroform fumigation-extraction method, alkali absorption method and titration or colorimetry to obtain the microbial data. Our results showed that soil physical-chemical characters remarkably differed among the NSFs. Microbial biomass carbon (Cmic) was the highest in wilson spruce soils, while microbial biomass nitrogen (Nmic) was the highest in sharptooth oak soils. Moreover, the highest basal respiration was found in the spruce soils, but mixed, Chinese pine and spruce stands exhibited a higher soil qCO2. The spruce soils had the highest Cmic/Nmic ratio, the greatest Nmic/TN and Cmic/Corg ratios were found in the oak soils. Additionally, the spruce soils had the maximum invertase activity and the minimum urease and catalase activities, but the maximum urease and catalase activities were found in the mixed stand. The Pearson correlation and principle component analyses revealed that the soils of spruce and oak stands obviously discriminated from other NSFs, whereas the others were similar. This suggested that the forest types affected soil microbial properties significantly due to differences in soil physical-chemical features.

  4. 78 FR 14357 - Certain Compact Fluorescent Reflector Lamps, Products Containing Same and Components Thereof...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... COMMISSION Certain Compact Fluorescent Reflector Lamps, Products Containing Same and Components Thereof... importation of certain compact fluorescent reflector lamps, products containing same and components thereof by... importation of certain compact fluorescent reflector lamps, products containing same and components thereof...

  5. Laser ranging retro-reflector: continuing measurements and expected results.

    PubMed

    Alley, C O; Chang, R F; Currie, D G; Poultney, S K; Bender, P L; Dicke, R H; Wilkinson, D T; Faller, J E; Kaula, W M; Macdonald, G J; Mulholland, J D; Plotkin, H H; Carrion, W; Wampler, E J

    1970-01-30

    After successful acquisition in August of reflected ruby laser pulses from the Apollo 11 laser ranging retro-reflector (LRRR) with the telescopes at the Lick and McDonald observatories, repeated measurements of the round-trip travel time of light have been made from the McDonald Observatory in September with an equivalent range precision of +/-2.5 meters. These acquisition period observations demonstrated the performance of the LRRR through lunar night and during sunlit conditions on the moon. Instrumentation activated at the McDonald Observatory in October has yielded a precision of +/-0.3 meter, and improvement to +/-0.15 meter is expected shortly. Continued monitoring of the changes in the earth-moon distance as measured by the round-trip travel time of light from suitably distributed earth stations is expected to contribute to our knowledge of the earth-moon system.

  6. Double-loop frequency selective surfaces for multi frequency division multiplexing in a dual reflector antenna

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao (Inventor)

    1994-01-01

    A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.

  7. Synthesis, characterization and biocidal activities of Schiff base polychelates containing polyurethane links in the main chain

    NASA Astrophysics Data System (ADS)

    Hasnain, Sumaiya; Nishat, Nahid

    The concept of combining metallo-polymers with urethanes offers a versatile approach for the synthesis of new polymeric materials. Polyurethane containing transition metals was synthesized by the reaction of Schiff base metal complex with toluene 2,4 diisocyanate. The proposed structures were confirmed by elemental analysis, 1H NMR, 13C NMR and FT-IR. The geometry is determined by UV-Visible spectra and magnetic moment measurements, which reveals that the Mn(II), Co(II) and Ni(II) complexes have octahedral geometry while square planer geometry is reported for Cu(II) and tetrahedral for Zn(II) complex. The antimicrobial activities are determined using the agar well diffusion method with Staphylococcus aureus, Escherichia coli, Bacillus subtilis (bacteria), Aspergillus niger, Candida albicans and Aspergillus flavus (yeast). All the polymeric metal complexes show comparatively good biocidal activity, which is further enhanced after polymerization.

  8. 46 CFR 28.235 - Anchors and radar reflectors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Anchors and radar reflectors. 28.235 Section 28.235....235 Anchors and radar reflectors. (a) Each vessel must be fitted with an anchor(s) and chain(s), cable... rigged with gear that provides a radar signature from a distance of 6 miles, each nonmetallic hull...

  9. 46 CFR 28.235 - Anchors and radar reflectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Anchors and radar reflectors. 28.235 Section 28.235....235 Anchors and radar reflectors. (a) Each vessel must be fitted with an anchor(s) and chain(s), cable... rigged with gear that provides a radar signature from a distance of 6 miles, each nonmetallic hull...

  10. 46 CFR 28.235 - Anchors and radar reflectors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Anchors and radar reflectors. 28.235 Section 28.235....235 Anchors and radar reflectors. (a) Each vessel must be fitted with an anchor(s) and chain(s), cable... rigged with gear that provides a radar signature from a distance of 6 miles, each nonmetallic hull...

  11. 46 CFR 28.235 - Anchors and radar reflectors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Anchors and radar reflectors. 28.235 Section 28.235....235 Anchors and radar reflectors. (a) Each vessel must be fitted with an anchor(s) and chain(s), cable... rigged with gear that provides a radar signature from a distance of 6 miles, each nonmetallic hull...

  12. 46 CFR 28.235 - Anchors and radar reflectors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Anchors and radar reflectors. 28.235 Section 28.235....235 Anchors and radar reflectors. (a) Each vessel must be fitted with an anchor(s) and chain(s), cable... rigged with gear that provides a radar signature from a distance of 6 miles, each nonmetallic hull...

  13. Detail of 25' highband reflector screen poles with monopole antenna ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of 25' high-band reflector screen poles with monopole antenna elements behind, note the metal sleeve bases of the reflector screen poles and the guy wire anchors from the dipole antenna elements (left foreground), view facing north northwest - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  14. Detail of 25' highband reflector screen pole showing the horizontal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of 25' high-band reflector screen pole showing the horizontal wood beams and vertical wires hung from ceramic insulators, note the dipole antenna element and 94' low-band reflector screen poles in background, view facing north - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  15. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District Commander may require or authorize the installation of radar reflectors and racons on bridge structures, stakes... bridge channel piers. Racons are used to mark the centerline of the channel....

  16. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District Commander may require or authorize the installation of radar reflectors and racons on bridge structures, stakes... bridge channel piers. Racons are used to mark the centerline of the channel....

  17. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District Commander may require or authorize the installation of radar reflectors and racons on bridge structures, stakes... bridge channel piers. Racons are used to mark the centerline of the channel....

  18. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District Commander may require or authorize the installation of radar reflectors and racons on bridge structures, stakes... bridge channel piers. Racons are used to mark the centerline of the channel....

  19. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District Commander may require or authorize the installation of radar reflectors and racons on bridge structures, stakes... bridge channel piers. Racons are used to mark the centerline of the channel....

  20. Modeling Mechanical Behavior of a Prismatic Replaceable Reflector Block

    SciTech Connect

    Robert Bratton

    2009-04-01

    This report outlines the development of finite element models used to determine temperature and stresses in a prismatic core reflector block. This initial analysis determines an appropriate temperature distribution in a prismatic reflector from limiting conditions in the adjacent fuel block based on simplifying assumptions.

  1. Study variants of hard CFRP reflector for intersatellite communication

    NASA Astrophysics Data System (ADS)

    Prosuntsov, PV; Reznik, SV; Mikhailovsky, KV; Novikov, AD; Aung, Zaw Ye

    2016-10-01

    The paper deals with the justification of space antennas reflector layout for advanced telecommunication satellites. The selection of design decisions is based on numerical simulations of heat transfer and mechanics processes characteristic of the geostationary orbit conditions. The advantages of parabolic shell of small thickness reflector scheme reinforced with star-shaped ribs on the convex side are demonstrated.

  2. X-ray resonator with pear-shaped reflectors

    SciTech Connect

    Churikov, V A

    2003-11-30

    An X-ray resonator design is proposed in which peculiar pear-shaped reflectors, which are grazing-incidence X-ray mirrors, serve as optical elements. Special features of this resonator are relatively high reflector efficiencies and the axial symmetry of the output radiation. (resonators)

  3. MainXchange in the Classroom: The New Internet Stock Market Game. Teacher's Guide and Student Activities.

    ERIC Educational Resources Information Center

    1998

    This teaching guide/student activities booklet, for grades 6-9 and 7-11, outlines an Internet-based stock exchange simulation that allows students to learn about the stock market in a fun format. The simulation (the "MainXchange") described in the booklet offers students the opportunity to engage in "real-life" investing, while…

  4. Simultaneous inversion of 3D velocity structure, hypocenter locations, and reflector geometry in Cascadia

    NASA Astrophysics Data System (ADS)

    Preston, Leiph Alexander

    We develop and apply a non-linear inversion of direct and wide-angle reflection travel times for 3-D P-wave velocity structure, earthquake hypocenters, and reflector geometry under NW Washington focusing on the structure of the subducting Juan de Fuca plate. The first-arrival travel times are derived from both active-source experiments and from local earthquakes. The reflection arrivals were picked from data collected during the 1998 Wet SHIPS active-source experiment, which consisted of air-gun sources within the inland water-ways of NW Washington and SW British Columbia to land-based stations. Our inversion procedure reduces the well-known trade-off between reflector position and the velocities above it by the combination of simultaneous inversion and adequate crossing paths. We interpret the wide-angle reflector as the Moho of the subducting Juan de Fuca slab. The relocated intraslab earthquakes separate into two groups: those located up-dip of the 45km reflector depth contour generally lie below the reflector in material whose velocity exceeds 7.7km/s, placing them within the subducting mantle, while those down-dip of this contour occur within material whose velocities are 6.8--7.5km/s, placing them within subducted oceanic crust. We interpret these groups of earthquakes as resulting from serpentine dehydration in the subducted mantle and the basalt to eclogite transformation in the subducted crust. We have performed velocity checkerboard, slab velocity resolution, and parameter sensitivity tests to estimate our ability to resolve the relationship among the reflector, intraslab hypocenters, and slab velocity structure. These tests indicate we have the necessary resolvability and can distinguish the relative locations among the velocities, reflector, and intraslab hypocenters within the subducting slab to +/-2km. The occurrence of events within the subducted mantle geometrically allows for larger magnitude earthquakes than could occur if they were confined to

  5. Baccharis dracunculifolia, the main botanical source of Brazilian green propolis, displays antiulcer activity.

    PubMed

    Lemos, Marivane; de Barros, Muriel Primon; Sousa, João Paulo Barreto; da Silva Filho, Ademar Alves; Bastos, Jairo Kenupp; de Andrade, Sérgio Faloni

    2007-04-01

    Baccharis dracunculifolia is the most important botanical source of Southeastern Brazilian propolis, known as green propolis for its colour. In a previous study, we described the gastric protective effect of the hydroalcoholic extract of Brazilian green propolis. We therefore wanted to investigate the possibility of using B. dracunculifolia extract for antiulcer treatment. This study was undertaken to evaluate the anti-ulcerogenic property of hydroalcoholic extract of B. dracunculifolia aerial parts. The HPLC analysis of the chemical composition of B. dracunculifolia extract used in this study revealed the presence mainly of cinnamic acid derivates and flavonoids. Doses of 50, 250 and 500 mg/kg of B. dracunculifolia crude extract and positive controls (omeprazole or cimetidine) significantly diminished the lesion index, the total lesion area and the percentage of lesion compared with negative control groups. The percentage of ulcer inhibition was significantly higher in groups treated with B. dracunculifolia, cimetidine or omeprazole, with all protocols used, compared with negative control groups. Regarding the model of gastric secretion, reductions in the volume of gastric juice and total acidity were observed, as well as an increase in the gastric pH. These results were similar to results from studies carried out with green propolis extract. Although more investigations are required, our results suggest that B. dracunculifolia has potential to be used as a phytotherapic preparation for the treatment of gastric ulcer.

  6. Self-clamping arc light reflector for welding torch

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S. (Inventor)

    1987-01-01

    This invention is directed to a coaxial extending metal mirror reflector attached to the electrode housing or gas cup on a welding torch. An electric welding torch with an internal viewing system for robotic welding is provded with an annular arc light reflector to reflect light from the arc back onto the workpiece. The reflector has a vertical split or gap in its surrounding wall to permit the adjacent wall ends forming the split to be sprung open slightly to permit the reflector to be removed or slipped onto the torch housing or gas cup. The upper opening of the reflector is slightly smaller than the torch housing or gas cup and therefore, when placed on the torch housing or gas cup has that springiness to cause it to clamp tightly on the housing or gas cup. The split or gap also serves to permit the feed of weld wire through to the weld area,

  7. Self-clamping arc light reflector for welding torch

    NASA Astrophysics Data System (ADS)

    Gordon, Stephen S.

    1987-07-01

    This invention is directed to a coaxial extending metal mirror reflector attached to the electrode housing or gas cup on a welding torch. An electric welding torch with an internal viewing system for robotic welding is provded with an annular arc light reflector to reflect light from the arc back onto the workpiece. The reflector has a vertical split or gap in its surrounding wall to permit the adjacent wall ends forming the split to be sprung open slightly to permit the reflector to be removed or slipped onto the torch housing or gas cup. The upper opening of the reflector is slightly smaller than the torch housing or gas cup and therefore, when placed on the torch housing or gas cup has that springiness to cause it to clamp tightly on the housing or gas cup. The split or gap also serves to permit the feed of weld wire through to the weld area,

  8. The cyclic AMP receptor protein is the main activator of pectinolysis genes in Erwinia chrysanthemi.

    PubMed Central

    Reverchon, S; Expert, D; Robert-Baudouy, J; Nasser, W

    1997-01-01

    The main virulence factors of the phytopathogenic bacterium Erwinia chrysanthemi are pectinases that cleave pectin, a major constituent of the plant cell wall. Although physiological studies suggested that pectinase production in Erwinia species is subjected to catabolite repression, the direct implication of the cyclic AMP receptor protein (CRP) in this regulation has never been demonstrated. To investigate the role of CRP in pectin catabolism, we cloned the E. chrysanthemi crp gene by complementation of an Escherichia coli crp mutation and then constructed E. chrysanthemi crp mutants by reverse genetics. The carbohydrate fermentation phenotype of the E. chrysanthemi crp mutants is similar to that of an E. coli crp mutant. Furthermore, these mutants are unable to grow on pectin or polygalacturonate as the sole carbon source. Analysis of the nucleotide sequence of the E. chrysanthemi crp gene revealed the presence of a 630-bp open reading frame (ORF) that codes for a protein highly similar to the CRP of E. coli. Using a crp::uidA transcriptional fusion, we demonstrated that the E. chrysanthemi CRP represses its own expression, probably via a mechanism similar to that described for the E. coli crp gene. Moreover, in the E. chrysanthemi crp mutants, expression of pectinase genes (pemA, pelB, pelC, pelD, and pelE) and of genes of the intracellular part of the pectin degradation pathway (ogl, kduI, and kdgT), which are important for inducer formation and transport, is dramatically reduced in induced conditions. In contrast, expression of pelA, which encodes a pectate lyase important for E. chrysanthemi pathogenicity, seems to be negatively regulated by CRP. The E. chrysanthemi crp mutants have greatly decreased maceration capacity in potato tubers, chicory leaves, and celery petioles as well as highly diminished virulence on saintpaulia plants. These findings demonstrate that CRP plays a crucial role in expression of the pectinolysis genes and in the pathogenicity of E

  9. Collagen-induced platelet activation mainly involves the protein kinase C pathway.

    PubMed Central

    Karniguian, A; Grelac, F; Levy-Toledano, S; Legrand, Y J; Rendu, F

    1990-01-01

    This study analyses early biochemical events in collagen-induced platelet activation. An early metabolic event occurring during the lag phase was the activation of PtdIns(4,5)P2-specific phospholipase C. Phosphatidic acid (PtdOH) formation, phosphorylation of P43 and P20, thromboxane B2 (TXB2) synthesis and platelet secretion began after the lag phase, and were similarly time-dependent, except for TXB2 synthesis, which was delayed. Collagen induced extensive P43 phosphorylation, whereas P20 phosphorylation was weak and always lower than with thrombin. The dose-response curves of P43 phosphorylation and granule secretion were similar, and both reached a peak at 7.5 micrograms of collagen/ml, a dose which induced half-maximal PtdOH and TXB2 formation. Sphingosine, assumed to inhibit protein kinase C, inhibited P43 phosphorylation and secretion in parallel. However, sphingosine was not specific for protein kinase C, since a 15 microM concentration, which did not inhibit P43 phosphorylation, blocked TXB2 synthesis by 50%. Sphingosine did not affect PtdOH formation at all, even at 100 microM, suggesting that collagen itself induced this PtdOH formation, independently of TXB2 generation. The absence of external Ca2+ allowed the cleavage of polyphosphoinositides and the accumulation of InsP3 to occur, but impaired P43 phosphorylation, PtdOH and TXB2 formation, and secretion; these were only restored by adding 0.11 microM-Ca2+. In conclusion, stimulation of platelet membrane receptors for collagen initiates a PtdInsP2-specific phospholipase C activation, which is independent of external Ca2+, and might be the immediate receptor-linked response. A Ca2+ influx is indispensable to the triggering of subsequent platelet responses. This stimulation predominantly involves the protein kinase C pathway associated with secretion, and appears not to be mediated by TXB2, at least during its initial stage. Images Fig. 6. PMID:2163606

  10. Fundamental relation between the main parameters of the thermally activated transport phenomena in complex oxide melts

    NASA Astrophysics Data System (ADS)

    Gasik, M. M.; Gasik, M. I.; Leont'ev, L. I.; Dashevskii, V. Ya.; Griogorovich, K. V.

    2014-07-01

    The relation between the activation energy and the preexponential factor in the Arrhenius equation that describes the viscosity and electrical conductivity of oxide (slag) melts is systematically analyzed over wide composition and temperature ranges for the first time. When deriving this relation, we do not use any model concepts and assumptions concerning the structure of slag melts or the character of electric charge transfer in them. The fundamental applicability of the Meyer-Neldel rule for this relation is shown and grounded. The application of this algorithm in practice can give information on the structure of experimental data, nonobvious correlations, and possible relations of a higher order and can quantitatively predict the behavior of parameters, including the range outside experimentally determined data.

  11. Deployment simulation of a deployable reflector for earth science application

    NASA Astrophysics Data System (ADS)

    Wang, Xiaokai; Fang, Houfei; Cai, Bei; Ma, Xiaofei

    2015-10-01

    A novel mission concept namely NEXRAD-In-Space (NIS) has been developed for monitoring hurricanes, cyclones and other severe storms from a geostationary orbit. It requires a space deployable 35-meter diameter Ka-band (35 GHz) reflector. NIS can measure hurricane precipitation intensity, dynamics and its life cycle. These information is necessary for predicting the track, intensity, rain rate and hurricane-induced floods. To meet the requirements of the radar system, a Membrane Shell Reflector Segment (MSRS) reflector technology has been developed and several technologies have been evaluated. However, the deployment analysis of this large size and high-precision reflector has not been investigated. For a pre-studies, a scaled tetrahedral truss reflector with spring driving deployment system has been made and tested, deployment dynamics analysis of this scaled reflector has been performed using ADAMS to understand its deployment dynamic behaviors. Eliminating the redundant constraints in the reflector system with a large number of moving parts is a challenging issue. A primitive joint and flexible struts were introduced to the analytical model and they can effectively eliminate over constraints of the model. By using a high-speed camera and a force transducer, a deployment experiment of a single-bay tetrahedral module has been conducted. With the tested results, an optimization process has been performed by using the parameter optimization module of ADAMS to obtain the parameters of the analytical model. These parameters were incorporated to the analytical model of the whole reflector. It is observed from the analysis results that the deployment process of the reflector with a fixed boundary experiences three stages. These stages are rapid deployment stage, slow deployment stage and impact stage. The insight of the force peak distributions of the reflector can help the optimization design of the structure.

  12. Impact of HFIR LEU Conversion on Beryllium Reflector Degradation Factors

    SciTech Connect

    Ilas, Dan

    2013-10-01

    An assessment of the impact of low enriched uranium (LEU) conversion on the factors that may cause the degradation of the beryllium reflector is performed for the High Flux Isotope Reactor (HFIR). The computational methods, models, and tools, comparisons with previous work, along with the results obtained are documented and discussed in this report. The report documents the results for the gas and neutronic poison production, and the heating in the beryllium reflector for both the highly enriched uranium (HEU) and LEU HFIR configurations, and discusses the impact that the conversion to LEU may have on these quantities. A time-averaging procedure was developed to calculate the isotopic (gas and poisons) production in reflector. The sensitivity of this approach to different approximations is gauged and documented. The results show that the gas is produced in the beryllium reflector at a total rate of 0.304 g/cycle for the HEU configuration; this rate increases by ~12% for the LEU case. The total tritium production rate in reflector is 0.098 g/cycle for the HEU core and approximately 11% higher for the LEU core. A significant increase (up to ~25%) in the neutronic poisons production in the reflector during the operation cycles is observed for the LEU core, compared to the HEU case, for regions close to the core s horizontal midplane. The poisoning level of the reflector may increase by more than two orders of magnitude during long periods of downtime. The heating rate in the reflector is estimated to be approximately 20% lower for the LEU core than for the HEU core. The decrease is due to a significantly lower contribution of the heating produced by the gamma radiation for the LEU core. Both the isotopic (gas and neutronic poisons) production and the heating rates are spatially non-uniform throughout the beryllium reflector volume. The maximum values typically occur in the removable reflector and close to the midplane.

  13. Evaluation of Essential Oil and its Three Main Active Ingredients of Chinese Chenopodium ambrosioides (Family: Chenopodiaceae) against Blattella germanica

    PubMed Central

    Zhu, Wei Xiang; Zhao, Kun; Chu, Sha Sha; Liu, Zhi Long

    2012-01-01

    Background: The efficacy of essential oil of Chenopodium ambrosioides flowering aerial parts and its three main active ingredients was evaluated against Blattella germanica male adults. Methods: Composition of essential oil was determined by GC-MS. Topical application bioassay was used to evaluate contact toxicity of essential oil and three main components. Fumigant toxicity of essential oil and its main components was measured using a sealed space method. Results: Twenty-two components were identified in the essential oil and the main components were (Z)-ascaridole (29.7%), isoascaridole (13.0%), ρ-cymene (12.7%) and piperitone (5.0%). The essential oil and (Z)-ascaridole, isoascaridole and ρ-cymene possessed fumigant toxicity against male German cockroaches with LC50 values of 4.13, 0.55, 2.07 and 6.92 mg/L air, respectively. Topical application bioassay showed that all the three compounds were toxic to male German cockroaches and (Z)-ascaridole was the strongest with a LD50 value of 22.02 μg/adult while the crude oil with a LD50 value of 67.46 μg/adult. Conclusion: The essential oil from Chinese C. ambrosioides and its three main active ingredients may be explored as natural potential insecticides in the control of cockroaches. PMID:23378965

  14. Climate change impacts on main agricultural activities in the Oltenia Plain (Romania)

    NASA Astrophysics Data System (ADS)

    Mitrica, B.; Mateescu, E.; Dragota, C.; Busuioc, A.; Grigorescu, I.; Popovici, A.

    2012-04-01

    Understanding the key drivers of agriculture in relation to climate change as well as their interrelationship with land management decisions and policies, one may be able to project future agricultural productions under certain economic, environmental, and social scenarios in order to minimize their negative impacts. The paper is aiming to stress upon the importance of modelling the potential impact of climate change on crop production, particularly under the current conditions when natural resources and food supplies are shortening in many parts of the world. Under the given circumstances, in assessing the impact of climate change on agriculture in the Oltenia Plain, the authors used a simulation model CERES (Crop-Environment Resource Synthesis), developed as a predictive and deterministic model, used for basic and applied research on the effects of climate (thermal regime, water stress) and management (fertilization practices, irrigation) on the growth and yield of different crops. In assessing the impact of climate change on maize and autumn wheat crops two applications of CERES model were used: CERES-Wheat and CERES-Maize overlapping two regional climatic scenarios for 2021-2050 and 2071-2100 periods. These models describe, based on daily data the basic biophysical processes which take place at the soil-plant-atmosphere interface as a response to the variability of different processes such as: photosynthesis, specific phonological phases, evapotranspiration, water dynamics in soil etc. Assessing the impact of climate change on agricultural productivity under the two regional climatic scenarios (2021-2050 and 2071-2100) will reveal their potential consequences on the main agricultural crops in the Oltenia Plain (autumn wheat and maize) depending on the interaction between local climatic conditions, the effect rising CO2 on photosynthesis and the genetical type of crops. Therefore, the autumn wheat benefits from the interaction between the rise of CO2 and air

  15. In vitro toxicological evaluation of essential oils and their main compounds used in active food packaging: A review.

    PubMed

    Llana-Ruiz-Cabello, Maria; Pichardo, Silvia; Maisanaba, Sara; Puerto, Maria; Prieto, Ana I; Gutiérrez-Praena, Daniel; Jos, Angeles; Cameán, Ana M

    2015-07-01

    Essential oils (EOs) and their main constituent compounds have been extensively investigated due to their application in the food industry for improving the shelf life of perishable products. Although they are still not available for use in food packaging in the market in Europe, considerable research in this field has been carried out recently. The safety of these EOs should be guaranteed before being commercialized. The aim of this work was to review the scientific publications, with a primary focus on the last 10 years, with respect to different in vitro toxicological aspects, mainly focussed on mutagenicity/genotoxicity. In general, fewer genotoxic studies have been reported on EOs in comparison to their main components, and most of them did not show mutagenic activity. However, more studies are needed in this field since the guidelines of the European Food Safety Authority have not always been followed accurately. The mutagenic/genotoxic activities of these substances have been related to metabolic activation. Therefore, in vivo tests are required to confirm the absence of genotoxic effects. Considering the great variability of the EOs and their main compounds, a case-by-case evaluation is needed to assure their safe use in food packaging.

  16. Present status of research activities relating global warming problems in Japan (mainly MITI and relating organizations)

    SciTech Connect

    Yokoyama, O.

    1993-12-31

    Japanese government has issued action program so called {open_quotes}Action Program to Arrest Global Warming{close_quotes} for preventing global warming at Oct., 1990. According to the program, CO{sub 2} emission should be stabilized on a per capita basis in the year 2000 and beyond at about same level as in 2000 by introducing several methods such as energy conservation, improvement of energy using efficiency, expanding use of renewable energy and so on. The basic concept, target and methods are summarized. At the same time, MITI published so called {open_quotes}New Earth 21{close_quotes} project which aims remedying the earth environment modified by human activities since industrial innovation began at about 200 years ago in coming 100 years. This plan proposed yearly step of research development of technology for mitigating CO{sub 2} emission. According to the MITI`s plan, 15 institutions belonging to AIST have carrying research for developing technology of reducing emission of CO{sub 2} and other greenhouse gases, with cooperation of other research organizations such as RITE (research Institute of Innovative Technology for Earth) and NEDO (New Energy and Industrial Technology Developing Organization). Time schedule of the research development by The New Earth 21 project is summarized in Table 2. Now, in Japan, many national institutions and universities, research works relating reduction and mitigation of GHG are carried out according to this guideline.

  17. Mentha suaveolens Ehrh. (Lamiaceae) Essential Oil and Its Main Constituent Piperitenone Oxide: Biological Activities and Chemistry.

    PubMed

    Božović, Mijat; Pirolli, Adele; Ragno, Rino

    2015-05-13

    Since herbal medicines play an important role in the treatment of a wide range of diseases, there is a growing need for their quality control and standardization. Mentha suaveolens Ehrh. (MS) is an aromatic herb with fruit and a spearmint flavor, used in the Mediterranean areas as a traditional medicine. It has an extensive range of biological activities, including cytotoxic, antimicrobial, antioxidant, anti-inflammatory, hypotensive and insecticidal properties, among others. This study aims to review the scientific findings and research reported to date on MS that prove many of the remarkable various biological actions, effects and some uses of this species as a source of bioactive natural compounds. On the other hand, piperitenone oxide (PO), the major chemical constituent of the carvone pathway MS essential oil, has been reported to exhibit numerous bioactivities in cells and animals. Thus, this integrated overview also surveys and interprets the present knowledge of chemistry and analysis of this oxygenated monoterpene, as well as its beneficial bioactivities. Areas for future research are suggested.

  18. Calamintha nepeta (L.) Savi and its Main Essential Oil Constituent Pulegone: Biological Activities and Chemistry.

    PubMed

    Božović, Mijat; Ragno, Rino

    2017-02-14

    Medicinal plants play an important role in the treatment of a wide range of diseases, even if their chemical constituents are not always completely recognized. Observations on their use and efficacy significantly contribute to the disclosure of their therapeutic properties. Calamintha nepeta (L.) Savi is an aromatic herb with a mint-oregano flavor, used in the Mediterranean areas as a traditional medicine. It has an extensive range of biological activities, including antimicrobial, antioxidant and anti-inflammatory, as well as anti-ulcer and insecticidal properties. This study aims to review the scientific findings and research reported to date on Calamintha nepeta (L.) Savi that prove many of the remarkable various biological actions, effects and some uses of this species as a source of bioactive natural compounds. On the other hand, pulegone, the major chemical constituent of Calamintha nepeta (L.) Savi essential oil, has been reported to exhibit numerous bioactivities in cells and animals. Thus, this integrated overview also surveys and interprets the present knowledge of chemistry and analysis of this oxygenated monoterpene, as well as its beneficial bioactivities. Areas for future research are suggested.

  19. [Ajoene the main active compound of garlic (Allium sativum): a new antifungal agent].

    PubMed

    Ledezma, Eliades; Apitz-Castro, Rafael

    2006-06-01

    The curative properties of garlic in medicine have been known for a long time. But, it was only in the last three decades when garlic properties were seriously investigated confirming its potential as therapeutic agent. Allicin, ajoene, thiosulfinates and a wide range of other organosulphurate compounds, are known to be the constituents linked to the garlic properties. Regarding the biochemical properties of these compounds, ajoene [(E,Z)-4,5,9 Trithiadodeca 1,6,11 Triene 9-oxide] is stable in water, and it can be obtained by chemical synthesis. There is evidence that some of the garlic constituents exert a wide variety of effects on different biological systems. However, ajoene is the garlic compound related to more biological activities, as showed in in vitro and in vivo systems. Those studies found that ajoene has antithrombotic, anti-tumoral,antifungal, and antiparasitic effects. This study deals with a recently described antifungal property of ajoene, and its potential use in clinical trails to treat several fungal infections.

  20. Benefit of Lunar Regolith on Reflector Mass Savings

    NASA Astrophysics Data System (ADS)

    Hatton, Steven A.; El-Genk, Mohamed S.

    2007-01-01

    The 2004 NASA Vision for Space Exploration calls for the return of mankind to the moon by no later than 2020, in preparation for an adventure to Mars and beyond. An envisioned lunar outpost will provide living quarters for initially 5- 10 astronauts for up to 2 weeks, and latter for science experiments, and recovery of mineral and indigenous resources for the day-to-day operation and production of propellant. These activities would require electrical and thermal powers in the order of 10's - 100's of kilowatts 24/7. Potential power options include photovoltaic, requiring massive batteries or fuel cells for energy storage during the long nights on the moon, and nuclear reactor power systems, which are much more compact and operate independent of the sun. This paper examines the benefit of using the lunar regolith as a supplemental neutron reflector on decreasing the launch mass of the Sectored Compact Reactor (SCoRe-S), developed at the Institute for Space and Nuclear Power Studies. In addition to providing at least $2.00 of hot-clean excess reactivity at the beginning of life, various SCoRe-S concepts investigated in this paper are at least $1.00 sub-critical when shutdown, and when the bare reactor cores are submerged in wet sand and flooded with seawater, following a launch abort accident. Design calculations performed using MCNP5 confirmed that using lunar regolith as supplementary reflector reduces the launch mass of the SCoRe-S cores by ~ 34% - 35%, or 150 - 200 kg, while satisfying the above reactivity requirements.

  1. Benefit of Lunar Regolith on Reflector Mass Savings

    SciTech Connect

    Hatton, Steven A.; El-Genk, Mohamed S.

    2007-01-30

    The 2004 NASA Vision for Space Exploration calls for the return of mankind to the moon by no later than 2020, in preparation for an adventure to Mars and beyond. An envisioned lunar outpost will provide living quarters for initially 5- 10 astronauts for up to 2 weeks, and latter for science experiments, and recovery of mineral and indigenous resources for the day-to-day operation and production of propellant. These activities would require electrical and thermal powers in the order of 10's - 100's of kilowatts 24/7. Potential power options include photovoltaic, requiring massive batteries or fuel cells for energy storage during the long nights on the moon, and nuclear reactor power systems, which are much more compact and operate independent of the sun. This paper examines the benefit of using the lunar regolith as a supplemental neutron reflector on decreasing the launch mass of the Sectored Compact Reactor (SCoRe-S), developed at the Institute for Space and Nuclear Power Studies. In addition to providing at least $2.00 of hot-clean excess reactivity at the beginning of life, various SCoRe-S concepts investigated in this paper are at least $1.00 sub-critical when shutdown, and when the bare reactor cores are submerged in wet sand and flooded with seawater, following a launch abort accident. Design calculations performed using MCNP5 confirmed that using lunar regolith as supplementary reflector reduces the launch mass of the SCoRe-S cores by {approx} 34% - 35%, or 150 - 200 kg, while satisfying the above reactivity requirements.

  2. Imaging with Spherically Bent Crystals or Reflectors

    SciTech Connect

    Bitter, M; Hill, K W; Scott, S; Ince-Cushman, A; Reinke, M; Podpaly, Y; Rice, J E; Beiersdorfer, P

    2010-06-01

    This paper consists of two parts: Part I describes the working principle of a recently developed x-ray imaging crystal spectrometer, where the astigmatism of spherically bent crystals is being used with advantage to record spatially resolved spectra of highly charged ions for Doppler measurements of the ion-temperature and toroidal plasmarotation- velocity profiles in tokamak plasmas. This type of spectrometer was thoroughly tested on NSTX and Alcator C-Mod, and its concept was recently adopted for the design of the ITER crystal spectrometers. Part II describes imaging schemes, where the astigmatism has been eliminated by the use of matched pairs of spherically bent crystals or reflectors. These imaging schemes are applicable over a wide range of the electromagnetic radiation, which includes microwaves, visible light, EUV radiation, and x-rays. Potential applications with EUV radiation and x-rays are the diagnosis of laserproduced plasmas, imaging of biological samples with synchrotron radiation, and lithography.

  3. Multiple seismic reflectors in Earth's lowermost mantle.

    PubMed

    Shang, Xuefeng; Shim, Sang-Heon; de Hoop, Maarten; van der Hilst, Robert

    2014-02-18

    The modern view of Earth's lowermost mantle considers a D″ region of enhanced (seismologically inferred) heterogeneity bounded by the core-mantle boundary and an interface some 150-300 km above it, with the latter often attributed to the postperovskite phase transition (in MgSiO3). Seismic exploration of Earth's deep interior suggests, however, that this view needs modification. So-called ScS and SKKS waves, which probe the lowermost mantle from above and below, respectively, reveal multiple reflectors beneath Central America and East Asia, two areas known for subduction of oceanic plates deep into Earth's mantle. This observation is inconsistent with expectations from a thermal response of a single isochemical postperovskite transition, but some of the newly observed structures can be explained with postperovskite transitions in differentiated slab materials. Our results imply that the lowermost mantle is more complex than hitherto thought and that interfaces and compositional heterogeneity occur beyond the D″ region sensu stricto.

  4. Method of making reflecting film reflector

    DOEpatents

    Cottingham, James G.

    1980-01-01

    A reflector of the reflecting film type is disclosed and which may be used in a heliostatic system for concentrating solar energy and comprising a reflecting film bonded to an appropriate rigid substrate in such a way that specularity of a very high order is achieved. A method of bonding the reflecting film to the substrate is also disclosed and comprises the steps of initially adhering the film to a smooth, clean flat rigid surface with a non-bonding liquid between the rigid surface and film, and then bonding the substrate and film. The non-bonding liquid has a molecular adhesion greater than any stresses due to handling or curing of the bonding agent which is applied between the film and the opposing surface of the rigid substrate.

  5. The 20 GHz proof-of-concept test model results for a multiple scan beam dual reflector antenna

    NASA Technical Reports Server (NTRS)

    Roberts, T.; Smoll, A.; Luh, H.; Matthews, E. W.; Scott, W. G.

    1984-01-01

    A full scale 20 GHz antenna model was designed, fabricated and tested. The model is intended to test the low sidelobe beam scanning capability of a new class of an offset dual reflector and feed array configuration. The offset main reflector and subreflector surfaces are custom shaped by a computer synthesis procedure. The derived optics result in beam scan loss under 1 db over the + or - 12.3 beamwidths by + or - 5.8 beamwidths scan volume while maintaining low sidelobes. It is found that the measured and computed patterns are in good agreement.

  6. Inline microring reflector for photonic applications

    NASA Astrophysics Data System (ADS)

    Kang, Young Mo

    The microring is a compact resonator that is used as a versatile building block in photonic circuits ranging from filters, modulators, logic gates, sensors, switches, multiplexers, and laser cavities. The Bragg grating is a periodic structure that allows the selection of a narrow bandwidth of spectrum for stable lasing operation. In this dissertation, we study analysis and simulations of a compact microring based reflector assembled by forming a Bragg grating into a loop. With the appropriate design, the microring resonance can precisely align with the reflection peak of the grating while all other peaks are suppressed by reflection nulls of the grating. The field buildup at the resonance effectively amplifies small reflection of the grating, thereby producing significant overall reflection from the ring, and it is possible to achieve a stable narrow linewidth compact laser by forming a single mode laser cavity. The device operation principle is studied from two distinct perspectives; the first looks at coupling of two contra-directional traveling waves within the ring whereas the second aspect investigates relative excitation of the two competing microring resonant modes. In the former method, we relate the steady state amplitudes of the two traveling waves to the reflection spectrum of the grating and solve for the reflection and transmission response for each wavelength of interest. In the latter approach, we expand the field in terms of the resonant modes of the ring cavity and derive transfer functions for reflection and transmission from the nearby mode frequencies. The angular periodicity of the reflective microring geometry allows us to effectively simulate the resonant modes from a computational domain of a single period grating when the continuity boundary condition is applied. We successfully predict the reflection and transmission response of a Si3N 4/SiO2 microring reflector using this method---otherwise too large to carry out full-wave simulation

  7. Effects of essential oil extracted from Nigella sativa (L.) seeds and its main components on human neutrophil elastase activity.

    PubMed

    Kacem, Rachid; Meraihi, Zahia

    2006-04-01

    The effects of essential oil extracted from Nigella sativa (L.) seeds and its main components on human neutrophil elastase (HNE) activity were investigated. Essential oil was extracted from N. sativa (L.) seeds using hydrodistillation. The yield was equal to 0.4%. Inhibition of HNE activity by essential oil was found to be dose dependent. The highest inhibitory concentration (HIC) of essential oil which caused total inhibition of HNE activity was 5.8 mg/ml. Microassays carried out to evaluate the inhibitory effect of major components of essential oil on HNE activity revealed that carvacrol (5-isopropyl-2-methylphenol) showed marked HNE inhibitory activity with a very low IC(50) value (12 microM). Based on these results, the inhibitory effects of essential oil on HNE activity are due to the presence of bioactive molecules, mainly carvacrol this compound is an inhibitor of HNE and could be considered as a natural antielastase agent and possible candidate for phytotherapy in the treatment of injuries that appear in some pathologic cases such as chronic obstructive pulmonary disease and emphysema.

  8. A generalized method for determining radiation patterns of aperture antennas and its application to reflector antennas. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Paknys, J. R.

    1982-01-01

    The reflector antenna may be thought of as an aperture antenna. The classical solution for the radiation pattern of such an antenna is found by the aperture integration (AI) method. Success with this method depends on how accurately the aperture currents are known beforehand. In the past, geometrical optics (GO) has been employed to find the aperture currents. This approximation is suitable for calculating the main beam and possibly the first few sidelobes. A better approximation is to use aperture currents calculated from the geometrical theory of diffraction (GTD). Integration of the GTD currents over and extended aperture yields more accurate results for the radiation pattern. This approach is useful when conventional AI and GTD solutions have no common region of validity. This problem arises in reflector antennas. Two dimensional models of parabolic reflectors are studied; however, the techniques discussed can be applied to any aperture antenna.

  9. Offset dual-shaped reflectors for dual chamber compact ranges

    NASA Technical Reports Server (NTRS)

    Galindo-Israel, Victor; Imbriale, William A.; Rengarajan, Sembiam R.; Mittra, Raj

    1991-01-01

    The application of the theory of the synthesis of offset dual-shaped reflectors to the design of compact ranges is examined. The object of the compact range is to provide a uniform plane wave with minimum amplitude and phase ripple over as large a volume as possible for a given size reflector. Ripple can be lowered by reducing the edge diffraction from the reflector producing the plane wave. This has been done either by serrating or rolling the edge. An alternative approach is to use dual offset-shaped reflector synthesis techniques to produce a reflector aperture distribution that is uniform over most of the aperture, but with a Gaussian taper near the edge. This approach can be used together with rolling and/or serration if desirable. The amount of phase and amplitude ripple obtained with two different dual-shaped reflector designs is studied as a function of position in the plane wave zone and reflector size in wavelengths. The amount of both transverse and longitudinal (z-component) cross polarization is studied.

  10. Apparatus For Linewidth Reduction in Distributed Feedback or Distributed Bragg Reflector Semiconductor Lasers Using Vertical Emission

    NASA Technical Reports Server (NTRS)

    Cook, Anthony L. (Inventor); Hendricks, Herbert D. (Inventor)

    2000-01-01

    The linewidth of a distributed feedback semiconductor laser or a distributed Bragg reflector laser having one or more second order gratings is reduced by using an external cavity to couple the vertical emission back into the laser. This method and device prevent disturbance of the main laser beam, provide unobstructed access to laser emission for the formation of the external cavity, and do not require a very narrow heat sink. Any distributed Bragg reflector semiconductor laser or distributed feedback semiconductor laser that can produce a vertical emission through the epitaxial material and through a window in the top metallization can be used. The external cavity can be formed with an optical fiber or with a lens and a mirror or grating.

  11. Mechanical behaviour of tape springs used in the deployment of reflectors around a solar panel

    NASA Astrophysics Data System (ADS)

    Dewalque, Florence; Collette, Jean-Paul; Brüls, Olivier

    2016-06-01

    In order to increase the production of power on small satellites, solar panels are commonly deployed and, in some cases, reflectors are added to improve the concentration factor on solar cells. In this work, reflectors are deployed by the means of compliant mechanisms known as tape springs. Their attractive characteristics are, among others, their passive behaviour, their self-locking capacity, their elastic deformations and their robustness. However, their mechanical behaviour is highly nonlinear and requires thorough analyses in order to develop predictive numerical models. It is shown here through parametric studies that the nonlinear behaviour of a tape spring is mainly governed by its geometry. Thus, for each specific application, its dimensions can be determined in order to minimise two critical features: the maximum stress affecting the structure and the maximum motion amplitude during deployment. In this paper, an optimisation procedure is proposed to meet these requirements.

  12. Benchmark Calculations for Reflector Effect in Fast Cores by Using the Latest Evaluated Nuclear Data Libraries

    NASA Astrophysics Data System (ADS)

    Fukushima, M.; Ishikawa, M.; Numata, K.; Jin, T.; Kugo, T.

    2014-04-01

    Benchmark calculations for reflector effects in fast cores were performed to validate the reliability of scattering data of structural materials in the major evaluated nuclear data libraries, JENDL-4.0, ENDF/B-VII.1 and JEFF-3.1.2. The criticalities of two FCA and two ZPR cores were analyzed by using a continuous energy Monte Carlo calculation code. The ratios of calculation to experimental values were compared between these cores and the sensitivity analyses were performed. From the results, the replacement reactivity from blanket to SS and Na reflector is better evaluated by JENDL-4.0 than by ENDF/B-VII.1 mainly due to the μbar values of Na and 52Cr.

  13. Deterministic and Monte-Carlo calculation schemes of the EPR core and its heavy steel reflector

    SciTech Connect

    Golfier, H.; Poinot-Salanon, C.; Nicolas, A.; Taieb, J.; Enderle, R.

    2006-07-01

    The aim of this work is to study an EPR core and its heavy reflector with the objective to quantify both the methodological biases within three calculation schemes and the impact on the core neutronic behaviour of the heavy reflector. To reach this, three different calculation schemes are presented here: - A reference calculation using the pointwise Monte-Carlo TRIPOLI4 code - A deterministic one, fully heterogeneous, based on the method of Characteristics - implemented in the APOLLO2 code - A diffusion approach using the mixed-dual finite elements with the CRONOS2 code. The first part of the paper gives the main characteristics of the core configuration chosen for the analyses. In a second part, the three different models and schemes are described and the third part is dedicated to the analysis of the results. (authors)

  14. Feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas

    NASA Technical Reports Server (NTRS)

    Stutzman, W. L.; Takamizawa, K.; Werntz, P.; Lapean, J.; Barts, R.; Shen, B.

    1991-01-01

    Virginia Tech is involved in a number of activities with NASA Langley related to large aperture radiometric antenna systems. These efforts are summarized and the focus of this report is on the feasibility study of a synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas; however, some results for all activities are reported.

  15. Deployable reflector design for Ku-band operation

    NASA Technical Reports Server (NTRS)

    Tankersley, B. C.

    1974-01-01

    A project was conducted to extend the deployable antenna technology state-of-the art through the design, analysis, construction, and testing of a lightweight, high surface tolerance, 12.5 foot diameter reflector for Ku-band operation. The applicability of the reflector design to the Tracking and Data Relay Satellite (TDRS) program was one requirement to be met. A documentary of the total program is presented. The performance requirements used to guide and constrain the design are discussed. The radio frequency, structural/dynamic, and thermal performance results are reported. Appendices are used to provide test data and detailed fabrication drawings of the reflector.

  16. Pressure surge reflector for pipe type cable system

    SciTech Connect

    Chu, H.; El Badaly, H.A.; Ghafurian, R. ); Aabo, T.; Ringlee, R.R.; Williams, J.A. ); Melcher, J. )

    1990-04-01

    This paper describes work performed on the development and testing of a pressure surge reflector, designed to reduce the pressure seen at potheads during an electrical failure in a pipe type cable system. The reflector is designed to protect the potheads from failing due to the pressure surge that may be large enough to fracture the porcelain, particularly when the electrical failure is physically close to the pothead. Test results show that the prototype reflector will lower the pressure significantly, bringing the pressure surge below the factory pressure test level for standard potheads.

  17. REFLECTOR CONTROL OF A BOILING-WATER REACTOR

    DOEpatents

    Treshow, M.

    1962-05-22

    A line connecting the reactor with a spent steam condenser contains a valve set to open when the pressure in the reactor exceeds a predetermined value and an orifice on the upstream side of the valve. Another line connects the reflector with this line between the orifice and the valve. An excess steam pressure causes the valve to open and the flow of steam through the line draws water out of the reflector. Provision is also made for adding water to the reflector when the steam pressure drops. (AEC)

  18. Discovery and characteristics of the rapidly rotating active asteroid (62412) 2000 SY178 in the main belt

    SciTech Connect

    Sheppard, Scott S.; Trujillo, Chadwick

    2015-02-01

    We report a new active asteroid in the main belt of asteroids between Mars and Jupiter. Object (62412) 2000 SY178 exhibited a tail in images collected during our survey for objects beyond the Kuiper Belt using the Dark Energy Camera on the CTIO 4 m telescope. We obtained broadband colors of 62412 at the Magellan Telescope, which, along with 62412's low albedo, suggests it is a C-type asteroid. 62412's orbital dynamics and color strongly correlate with the Hygiea family in the outer main belt, making it the first active asteroid known in this heavily populated family. We also find 62412 to have a very short rotation period of 3.33 ± 0.01 hours from a double-peaked light curve with a maximum peak-to-peak amplitude of 0.45 ± 0.01 mag. We identify 62412 as the fastest known rotator of the Hygiea family and the nearby Themis family of similar composition, which contains several known main belt comets. The activity on 62412 was seen over one year after perihelion passage in its 5.6 year orbit. 62412 has the highest perihelion and one of the most circular orbits known for any active asteroid. The observed activity is probably linked to 62412's rapid rotation, which is near the critical period for break-up. The fast spin rate may also change the shape and shift material around 62412's surface, possibly exposing buried ice. Assuming 62412 is a strengthless rubble pile, we find the density of 62412 to be around 1500 kg m{sup −3}.

  19. Ligand-binding specificity and promiscuity of the main lignocellulolytic enzyme families as revealed by active-site architecture analysis

    PubMed Central

    Tian, Li; Liu, Shijia; Wang, Shuai; Wang, Lushan

    2016-01-01

    Biomass can be converted into sugars by a series of lignocellulolytic enzymes, which belong to the glycoside hydrolase (GH) families summarized in CAZy databases. Here, using a structural bioinformatics method, we analyzed the active site architecture of the main lignocellulolytic enzyme families. The aromatic amino acids Trp/Tyr and polar amino acids Glu/Asp/Asn/Gln/Arg occurred at higher frequencies in the active site architecture than in the whole enzyme structure. And the number of potential subsites was significantly different among different families. In the cellulase and xylanase families, the conserved amino acids in the active site architecture were mostly found at the −2 to +1 subsites, while in β-glucosidase they were mainly concentrated at the −1 subsite. Families with more conserved binding amino acid residues displayed strong selectivity for their ligands, while those with fewer conserved binding amino acid residues often exhibited promiscuity when recognizing ligands. Enzymes with different activities also tended to bind different hydroxyl oxygen atoms on the ligand. These results may help us to better understand the common and unique structural bases of enzyme-ligand recognition from different families and provide a theoretical basis for the functional evolution and rational design of major lignocellulolytic enzymes. PMID:27009476

  20. Space Reflector Materials for Prometheus Application

    SciTech Connect

    J. Nash; V. Munne; LL Stimely

    2006-01-31

    The two materials studied in depth which appear to have the most promise in a Prometheus reflector application are beryllium (Be) and beryllium oxide (BeO). Three additional materials, magnesium oxide (MgO), alumina (Al{sub 2}O{sub 3}), and magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) were also recently identified to be of potential interest, and may have promise in a Prometheus application as well, but are expected to be somewhat higher mass than either a Be or BeO based reflector. Literature review and analysis indicates that material properties for Be are largely known, but there are gaps in the properties of Be0 relative to the operating conditions for a Prometheus application. A detailed preconceptual design information document was issued providing material properties for both materials (Reference (a)). Beryllium oxide specimens were planned to be irradiated in the JOY0 Japanese test reactor to partially fill the material property gaps, but more testing in the High Flux Isotope Reactor (HFIR) test reactor at Oak Ridge National Laboratory (ORNL) was expected to be needed. A key issue identified for BeO was obtaining material for irradiation testing with an average grain size of {approx}5 micrometers, reminiscent of material for which prior irradiation test results were promising. Current commercially available material has an average grain size of {approx}10 micrometers. The literature indicated that improved irradiation performance could be expected (e.g., reduced irradiation-induced swelling) with the finer grain size material. Confirmation of these results would allow the use of historic irradiated materials test results from the literature, reducing the extent of required testing and therefore the cost of using this material. Environmental, safety and health (ES&H) concerns associated with manufacturing are significant but manageable for Be and BeO. Although particulate-generating operations (e.g., machining, grinding, etc.) involving Be

  1. Proceedings of the Large Deployable Reflector Science and Technology Workshop. Volume 1: Executive Summary

    NASA Technical Reports Server (NTRS)

    Leidich, C. A.; Pittman, B.

    1984-01-01

    A large ambient temperature, for infrared submillimeter telescope in space was discussed. The results of the scientific and technical activities were summarized. The scientific effort consisted of reviewing the science rationale for the Large Deployable Reflector (LDR) and arriving at a concensus set of scientific requirements. The telescope requirements were then compared to the current and anticipated state of the various technologies involved, and the technological shortfalls identified.

  2. Prominent reflector beneath around the segmentation boundary between Tonankai-Nankai earthquake area

    NASA Astrophysics Data System (ADS)

    Nakanishi, A.; Shimomura, N.; Fujie, G.; Kodaira, S.; Obana, K.; Takahashi, T.; Yamamoto, Y.; Yamashita, M.; Takahashi, N.; Kaneda, Y.; Mochizuki, K.; Kato, A.; Iidaka, T.; Kurashimo, E.; Shinohara, M.; Takeda, T.; Shiomi, K.

    2013-12-01

    In the Nankai Trough subduction seismogenic zone, the Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. In most cases, first break of such large events of Nankai Trough usually begins from southwest off the Kii Peninsula so far. The idea of split Philippine Sea plate between the Kii Peninsula and the Shikoku Island, which explains seismicity, tectonic background, receiver function image and historical plate motion, was previously suggested. Moreover, between the Kii Peninsula and the Shikoku Island, there is a gap of deep low-frequency events observed in the belt-like zone along the strike of the subducting Philippine Sea plate. In 2010 and 2011, we conducted the large-scale high-resolution wide-angle and reflection (MCS) seismic study, and long-term observation from off Shikoku and Kii Peninsula. Marine active source seismic data have been acquired along grid two-dimensional profiles having the total length of ~800km/year. A three-dimensional seismic tomography using active and passive seismic data observed both land and ocean bottom stations have been also performed. From those data, we found a possible prominent reflector imaged in the offshore side in the Kii channel at the depth of ~18km. The velocity just beneath the reflector cannot be determined due to the lack of ray paths. Based of the amplitude information, we interpret the reflector as the forearc Moho based on the velocity gap (from ~6.4km/s to ~7.4km/s). However, the reflector is shallower than the forearc Moho of other area along the Nankai Trough. Similar reflectors are recognized along other seismic profiles around the Kii channel. In this presentation, we will show the result of structure analysis to understand the peculiar structure including the prominent reflector around the Kii channel. Relation between the structure and the existence of the segmentation of the Nankai megathrust earthquake or seismic gap of the deep low-frequency events will be also

  3. The basal forebrain modulates spontaneous activity of principal cells in the main olfactory bulb of anesthetized mice

    PubMed Central

    Zhan, Xiping; Yin, Pingbo; Heinbockel, Thomas

    2013-01-01

    Spontaneous activity is an important characteristic of the principal cells in the main olfactory bulb (MOB) for encoding odor information, which is modulated by the basal forebrain. Cholinergic activation has been reported to inhibit all major neuron types in the MOB. In this study, the effect of diagonal band (NDB) stimulation on mitral/tufted (M/T) cell spontaneous activity was examined in anesthetized mice. NDB stimulation increased spontaneous activity in 66 MOB neurons which lasted for 2–35 s before returning to the baseline level. The majority of the effected units showed a decrease of interspike intervals (ISI) at a range of 8–25 ms. Fifty-two percent of NDB stimulation responsive units showed intrinsic rhythmical bursting, which was enhanced temporarily by NDB stimulation, whereas the remaining non-rhythmic units were capable of synchronized bursting. The effect was attenuated by scopolamine in 21 of 27 units tested. Only four NDB units were inhibited by NDB stimulation, an inhibition that lasted less than 10 s. The NDB stimulation responsive neurons appeared to be M/T cells. Our findings demonstrate an NDB excitation effect on M/T neurons that mostly requires muscarinic receptor activation, and is likely due to non-selectivity of electrical stimulation. This suggests that cholinergic and a diverse group of non-cholinergic neurons in the basal forebrain co-ordinately modulate the dynamics of M/T cell spontaneous activity, which is fundamental for odor representation and attentional perception. PMID:24065892

  4. Microbiological analysis, antimicrobial activity, and heavy-metals content of Jordanian Ma'in hot-springs water.

    PubMed

    Shakhatreh, Muhamad Ali K; Jacob, Jacob H; Hussein, Emad I; Masadeh, Majed M; Obeidat, Safwan M; Juhmani, Abdul-Salam F; Abd Al-Razaq, Mutaz A

    2017-02-14

    Ma'in hot springs are known as sites of balneotherapy. However, little is known about their microbiology and chemistry. In this study, we aim at evaluating the antimicrobial activity of Ma'in hot-springs water (MHSW), studying its microbiology, and determining its physicochemical properties including the heavy metals content. Therefore, water samples were collected from Ma'in hot springs and tested for antimicrobial activity using agar diffusion method. Water was then cultivated on nutrient agar to isolate and identify the dominant bacteria by chemical and molecular methods. The identified strains were tested by cross streak method to evaluate their antimicrobial activity against different clinical and standard strains. Finally, water samples were chemically analyzed and the heavy-metals content was assessed. Results revealed that MHSW was not active against any of the clinical isolates. Nevertheless, MHSW was found to be active against five standard bacterial strains, namely, Staphylococcus epidermidis ATCC 12228 (inhibition zone: 20mm), Staphylococcus aureus ATCC 29213 (inhibition zone: 19mm), Micrococcus luteus ATCC 9341 (inhibition zone: 15.3mm), and Bacillus cereus ATCC 11778 (inhibition zone: 12.3mm). After cultivation of MHSW, five bacterial isolates were obtained and identified based on 16S rRNA gene analysis as new strains of Anoxybacillus flavithermus (identity percentage ranges between 96-99%). Physicochemical analysis revealed that the in situ temperature was 59°C, pH was 7.8, salinity was 1.6ppt, and dissolved oxygen was 3.8mgl(-1). In respect to heavy-metals content in MHSW, the following metals were present in the order: Cr (0.571ppm)>Mn(0.169ppm)>Fe (0.124ppm)>Zn (0.095)>Cu(0.070ppm)>Ni(0.058ppm)>Cd (0.023ppm)>Pb (0ppm). Cd, Cr, Ni and Mn were found to be higher than permissible levels set by international organizations and countries. This study highlights new chemical and microbiological data about Ma'in hot springs.

  5. Preliminary design approach for large high precision segmented reflectors

    NASA Technical Reports Server (NTRS)

    Mikulas, Martin M., Jr.; Collins, Timothy J.; Hedgepeth, John M.

    1990-01-01

    A simplified preliminary design capability for erectable precision segmented reflectors is presented. This design capability permits a rapid assessment of a wide range of reflector parameters as well as new structural concepts and materials. The preliminary design approach was applied to a range of precision reflectors from 10 meters to 100 meters in diameter while considering standard design drivers. The design drivers considered were: weight, fundamental frequency, launch packaging volume, part count, and on-orbit assembly time. For the range of parameters considered, on-orbit assembly time was identified as the major design driver. A family of modular panels is introduced which can significantly reduce the number of reflector parts and the on-orbit assembly time.

  6. Elevation of a portion of the reflector screen and antenna ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Elevation of a portion of the reflector screen and antenna circles from the interior, view facing southeast - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  7. 6. GENE WASH DAM, LOOKING NORTHWEST. SURVEY REFLECTOR IN FOREGROUND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. GENE WASH DAM, LOOKING NORTHWEST. SURVEY REFLECTOR IN FOREGROUND FOR MONITORING MOVEMENT OF DAM AND EARTH. - Gene Wash Reservoir & Dam, 2 miles west of Parker Dam, Parker Dam, San Bernardino County, CA

  8. Optical biometry of biological tissues by ellipsoidal reflectors

    NASA Astrophysics Data System (ADS)

    Bezuglyi, M. A.; Pavlovets, N. V.

    2013-06-01

    Possibilities of measuring systems that uses ellipsoidal reflectors for determining the optical parameters of biological tissue are studied. The modified inverse Monte Carlo method was designed for biomedical photometric system "biological tissue - ellipsoidal mirror."

  9. 16 CFR 1512.16 - Requirements for reflectors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... sidewalls or, alternatively, reflectors mounted on the spokes of each wheel, or, for non-caliper rim brake... must break before additional separation (peeling) from the rim is observed. (3) After...

  10. 16 CFR 1512.16 - Requirements for reflectors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... sidewalls or, alternatively, reflectors mounted on the spokes of each wheel, or, for non-caliper rim brake... must break before additional separation (peeling) from the rim is observed. (3) After...

  11. 16 CFR 1512.16 - Requirements for reflectors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... sidewalls or, alternatively, reflectors mounted on the spokes of each wheel, or, for non-caliper rim brake... must break before additional separation (peeling) from the rim is observed. (3) After...

  12. 16 CFR 1512.16 - Requirements for reflectors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sidewalls or, alternatively, reflectors mounted on the spokes of each wheel, or, for non-caliper rim brake... must break before additional separation (peeling) from the rim is observed. (3) After...

  13. 16 CFR 1512.16 - Requirements for reflectors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... sidewalls or, alternatively, reflectors mounted on the spokes of each wheel, or, for non-caliper rim brake... must break before additional separation (peeling) from the rim is observed. (3) After...

  14. A bionic approach to mathematical modeling the fold geometry of deployable reflector antennas on satellites

    NASA Astrophysics Data System (ADS)

    Feng, C. M.; Liu, T. S.

    2014-10-01

    Inspired from biology, this study presents a method for designing the fold geometry of deployable reflectors. Since the space available inside rockets for transporting satellites with reflector antennas is typically cylindrical in shape, and its cross-sectional area is considerably smaller than the reflector antenna after deployment, the cross-sectional area of the folded reflector must be smaller than the available rocket interior space. Membrane reflectors in aerospace are a type of lightweight structure that can be packaged compactly. To design membrane reflectors from the perspective of deployment processes, bionic applications from morphological changes of plants are investigated. Creating biologically inspired reflectors, this paper deals with fold geometry of reflectors, which imitate flower buds. This study uses mathematical formulation to describe geometric profiles of flower buds. Based on the formulation, new designs for deployable membrane reflectors derived from bionics are proposed. Adjusting parameters in the formulation of these designs leads to decreases in reflector area before deployment.

  15. Reflectors for SAR performance testing-second edition

    SciTech Connect

    Doerry, Armin Walter

    2014-02-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  16. Aluminum honeycomb reflector panels on James Clerk Maxwell Telescope

    NASA Astrophysics Data System (ADS)

    Greenhalgh, R. Justin S.

    1993-10-01

    The accuracy requirements and design philosophy of the JCMT reflector structure are briefly reviewed, leading to a steel space-frame with separate reflector panels. The choice of material for the panels is discussed, with particular emphasis on the properties of aluminum honeycomb composites. The development of the manufacturing process and the details of the process are described. Finally, statistics on the results of the manufacturing process are given.

  17. On the design of large space deployable modular antenna reflectors

    NASA Technical Reports Server (NTRS)

    Ribble, J. W.; Woods, A. A., Jr.

    1981-01-01

    The deployment kinematics, stowing philosophy, and deployment sequencing for large deployable antenna modules were verified. Mesh attachment methods compatible with full scale modules were devised. Parametric studies of large modular reflectors established size, mass, and aperture frequency capabilities for these assemblies. Preliminary studies were made devising means of delivering modules to orbit, and once there, of assembling the modules into complete modular antenna reflectors. The basic feasibility of creating mass efficient modules erectable into large structures in space was established.

  18. Ultralightweight Space Deployable Primary Reflector Demonstrator

    NASA Technical Reports Server (NTRS)

    Montgomery, Edward E., IV; Zeiders, Glenn W.; Smith, W. Scott (Technical Monitor)

    2002-01-01

    A concept has been developed and analyzed and several generational prototypes built for a gossamer-class deployable truss for a mirror or reflector with many smaller precisely-figured solid elements attached will, for at least the next several decades, minimize the mass of a large primary mirror assembly while still providing the high image quality essential for planet-finding and cosmological astronomical missions. Primary mirror segments are mounted in turn on ultralightweight thermally-formed plastic panels that hold clusters of mirror segments in rigid arrays whose tip/tilt and piston would be corrected over the scale of the plastic panels by the control segments. Prototype panels developed under this program are 45 cm wide and fabricated from commercially available Kaplan sheets. A three-strut octahedral tensegrity is the basis for the overall support structure. Each fundamental is composed of two such octahedrons, rotated oppositely about a common triangular face. Adjacent modules are joined at the nodes of the upper and lower triangles to form a deployable structure that could be made arbitrarily large. A seven-module dowel-and-wire prototype has been constructed. Deployment techniques based on the use of collapsing toggled struts with diagonal tensional elements allows an assembly of tensegrities to be fully collapsed and redeployed. The prototype designs will be described and results of a test program for measuring strength and deformation will be presented.

  19. Improved Monoblock laser brightness using external reflector.

    PubMed

    Hays, A D; Nettleton, John; Barr, Nick; Hough, Nathaniel; Goldberg, Lew

    2014-03-01

    The Monoblock laser has become the laser of choice in long-range, eye-safe laser range finders. It is eye-safe with emission at 1570 nm, high pulse energy, simple construction, and high efficiency when pumped by a laser-diode stack. Although the output beam divergence of a typical Monoblock with a 3  mm×3  mm cross section is relatively large (10-12 mrad), it can be reduced to <1  mrad using a telescope with large magnification. In this paper we present a simple and compact technique for achieving significant reduction in the Monoblock beam divergence using a partial reflector that is placed a short distance from the optical parametric oscillator (OPO). Using a 38 mm long Monoblock with a 10 mm long potassium titanyl phosphate OPO, we achieved a beam divergence of <4  mrad, corresponding to a >2.5× reduction from the unmodified laser. Performance using this technique with various feedback and etalon spacings is presented.

  20. Disordered animal multilayer reflectors and the localization of light

    PubMed Central

    Jordan, T. M.; Partridge, J. C.; Roberts, N. W.

    2014-01-01

    Multilayer optical reflectors constructed from ‘stacks’ of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered ‘coloured’ and more strongly disordered ‘silvery’ reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine–cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity. PMID:25339688

  1. Disordered animal multilayer reflectors and the localization of light.

    PubMed

    Jordan, T M; Partridge, J C; Roberts, N W

    2014-12-06

    Multilayer optical reflectors constructed from 'stacks' of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered 'coloured' and more strongly disordered 'silvery' reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine-cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity.

  2. Design method for four-reflector type beam waveguide systems

    NASA Technical Reports Server (NTRS)

    Betsudan, S.; Katagi, T.; Urasaki, S.

    1986-01-01

    Discussed is a method for the design of four reflector type beam waveguide feed systems, comprised of a conical horn and 4 focused reflectors, which are used widely as the primary reflector systems for communications satellite Earth station antennas. The design parameters for these systems are clarified, the relations between each parameter are brought out based on the beam mode development, and the independent design parameters are specified. The characteristics of these systems, namely spillover loss, crosspolarization components, and frequency characteristics, and their relation to the design parameters, are also shown. It is also indicated that design parameters which decide the dimensions of the conical horn or the shape of the focused reflectors can be unerringly established once the design standard for the system has been selected as either: (1) minimizing the crosspolarization component by keeping the spillover loss to within acceptable limits, or (2) minimizing the spillover loss by maintaining the crossover components below an acceptable level and the independent design parameters, such as the respective sizes of the focused reflectors and the distances between the focussed reflectors, etc., have been established according to mechanical restrictions. A sample design is also shown. In addition to being able to clarify the effects of each of the design parameters on the system and improving insight into these systems, the efficiency of these systems will also be increased with this design method.

  3. Why play an active role? A qualitative examination of lay citizens' main motives for participation in health promotion.

    PubMed

    Fienieg, Barbara; Nierkens, Vera; Tonkens, Evelien; Plochg, Thomas; Stronks, Karien

    2012-09-01

    While active participation is regarded essential in health promotion worldwide, its application proves to be challenging. Notably, participants' experiences are infrequently studied, and it is largely unknown why lay citizens would want to play an active role in promoting the health of the community they belong to. Aiming to produce practical insights to further the application of the participation principle, this qualitative study examined participants' driving motives in a diverse array of health promotion undertakings. Six projects in The Netherlands were used as case studies, including a community-project promoting mental health, peer education against harmful substance use, a health support group, health policy development, physical activity and healthy life style courses. The study involved 24 participants, who played a variety of active roles. Semi-structured interviews were conducted, transcribed verbatim and subjected to content analysis. We found four main motives driving lay citizens in their active participation in health promotion projects: 'purposeful action', 'personal development', 'exemplary status' and 'service and reciprocity'. The motives reflected crucially distinct personal desires in the participation process, namely to produce tangible results, to experience advancements for oneself, to gain personal recognition as a role model and to have or maintain valued relationships. The implications of the findings are discussed for researchers and professionals in health promotion.

  4. Variability of stellar granulation and convective blueshift with spectral type and magnetic activity. I. K and G main sequence stars

    NASA Astrophysics Data System (ADS)

    Meunier, N.; Lagrange, A.-M.; Mbemba Kabuiku, L.; Alex, M.; Mignon, L.; Borgniet, S.

    2017-01-01

    Context. In solar-type stars, the attenuation of convective blueshift by stellar magnetic activity dominates the RV (radial velocity) variations over the low amplitude signal induced by low mass planets. Models of stars that differ from the Sun will require a good knowledge of the attenuation of the convective blueshift to estimate its impact on the variations. Aims: It is therefore crucial to precisely determine not only the amplitude of the convective blueshift for different types of stars, but also the dependence of this convective blueshift on magnetic activity, as these are key factors in our model producing the RV. Methods: We studied a sample of main sequence stars with spectral types from G0 to K2 and focused on their temporally averaged properties: the activity level and a criterion allowing to characterise the amplitude of the convective blueshift. This criterion is derived from the dependence of the convective blueshift with the intensity at the bottom of a large set of selected spectral lines. Results: We find the differential velocity shifts of spectral lines due to convection to depend on the spectral type, the wavelength (this dependence is correlated with the Teff and activity level), and on the activity level. This allows us to quantify the dependence of granulation properties on magnetic activity for stars other than the Sun. We are indeed able to derive a significant dependence of the convective blueshift on activity level for all types of stars. The attenuation factor of the convective blueshift appears to be constant over the considered range of spectral types. We derive a convective blueshift which decreases towards lower temperatures, with a trend in close agreement with models for Teff lower than 5800 K, but with a significantly larger global amplitude. Differences also remain to be examined in detail for larger Teff. We finally compare the observed RV variation amplitudes with those that could be derived from our convective blueshift using

  5. Intervening in Earth's climate system through space-based solar reflectors

    NASA Astrophysics Data System (ADS)

    Salazar, F. J. T.; McInnes, C. R.; Winter, O. C.

    2016-07-01

    Several space-based climate engineering methods, including shading the Earth with a particle ring for active cooling, or the use of orbital reflectors to increase the total insolation of Mars for climate warming have been considered to modify planetary climates in a controller manner. In this study, solar reflectors on polar orbits are proposed to intervene in the Earth's climate system, involving near circular polar orbits normal to the ecliptic plane of the Earth. Similarly, a family of displaced polar orbits (non-Keplerian orbits) are also characterized to mitigate future natural climate variability, producing a modest global temperature increase, again to compensate for possible future cooling. These include deposition of aerosols in the stratosphere from large volcanic events. The two-body problem is considered, taking into account the effects of solar radiation pressure and the Earth's J2 oblateness perturbation.

  6. Systematic analysis of diffuse rear reflectors for enhanced light trapping in silicon solar cells

    SciTech Connect

    Pfeffer, Florian; Eisenlohr, Johannes; Basch, Angelika; Hermle, Martin; Lee, Benjamin G.; Goldschmidt, Jan Christoph

    2016-08-01

    Simple diffuse rear reflectors can enhance the light path length of weakly absorbed near infrared light in silicon solar cells and set a benchmark for more complex and expensive light trapping structures like dielectric gratings or plasmonic particles. We analyzed such simple diffuse rear reflectors systematically by optical and electrical measurements. We applied white paint, TiO2 nanoparticles, white backsheets and a silver mirror to bifacial silicon solar cells and measured the enhancement of the external quantum efficiency for three different solar cell geometries: planar front and rear side, textured front and planar rear side, and textured front and rear side. We showed that an air-gap between the solar cell and the reflector decreases the absorption enhancement significantly, thus white paint and TiO2 nanoparticles directly applied to the rear cell surface lead to the highest short circuit current density enhancements. The short circuit current density gains for a 200 um thick planar solar cell reached up to 1.8 mA/cm2, compared to a non-reflecting black rear side and up to 0.8 mA/cm2 compared to a high-quality silver mirror rear side. For solar cells with textured front side the short circuit current density gains are in the range between 0.5 and 1.0 mA/cm2 compared to a non-reflecting black rear side and do not significantly depend on the angular characteristic of the rear side reflector but mainly on its absolute reflectance.

  7. Influence of pre-harvest red light irradiation on main phytochemicals and antioxidant activity of Chinese kale sprouts.

    PubMed

    Deng, Mingdan; Qian, Hongmei; Chen, Lili; Sun, Bo; Chang, Jiaqi; Miao, Huiying; Cai, Congxi; Wang, Qiaomei

    2017-05-01

    The effects of pre-harvest red light irradiation on main healthy phytochemicals as well as antioxidant activity of Chinese kale sprouts during postharvest storage were investigated. 6-day-old sprouts were treated by red light for 24h before harvest and sampled for further analysis of nutritional quality on the first, second and third day after harvest. The results indicated that red light exposure notably postponed the degradation of aliphatic, indole, and total glucosinolates during postharvest storage. The vitamin C level was remarkably higher in red light treated sprouts on the first and second day after harvest when compared with the control. In addition, red light treatment also enhanced the accumulation of total phenolics and maintained higher level of antioxidant activity than the control. All above results suggested that pre-harvest red light treatment might provide a new strategy to maintain the nutritive value of Chinese kale sprouts during postharvest storage.

  8. Study and comparison of the maximum stress directions and main fault orientations in some active zones in Iran

    NASA Astrophysics Data System (ADS)

    Forouhid, Khatereh; Faraji, Atefeh; Ghorashi, Manouchehr

    2010-05-01

    Study and comparison of the maximum stress directions and main fault orientations in some active zones in Iran Khatereh Forouhid, Manouchehr Ghorashi, Atefeh Faraji Institute of Geophysics, Tehran University, Tehran, Iran kforouhid@yahoo.com Farajiatefeh@yahoo.com The Iranian plateau is the widest active zone in Alpine-Himalayan collision system that is located between two stable platforms, the Arabia in southwest and Eurasia in northeast. The convergence of these two platforms towards each other is the main reason for seismicity and different styles of deformation observed in Iran. In this study, the Iranian plateau is divided into 7 regions based on their seismotectonic characteristics. These regions are; Zagros, Makran, East Iran, Alborz, Kopeh Dagh, Central Iran and Azarbayejan (northwest of Iran). In each region, focal mechanism solutions of early and modern instrumental earthquakes (the only source of information suitable to use for stress distribution study in Iran) with magnitudes more than 5.0 and their relations to active faults are considered. By studying each maximum stress direction based on a group of earthquake focal mechanisms and considering main fault orientations, each region is studied individually. According to these data, some of these regions are divided into smaller parts. These sub-divided parts have some characters that make them different from their neighbors in the same region. In this regard, Zagros is studied in detail based on seismotectonic characteristics and divided into three parts, with N-S maximum stress direction (compressional) in one part and two different kind of NE-SW direction in two other. We use this information to investigate the style and distribution of active faulting in the Zagros and the relationships of this activity with shortening of the Arabia-Eurasia collision. It is worth to mention that as the fault slip will almost occur in the direction of maximum resolved shear stress on the fault plane, probably strain

  9. Integrated photonics based on planar holographic Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Greiner, Christoph M.; Iazikov, Dmitri; Mossberg, Thomas W.

    2004-10-01

    Integrated holographics is a novel photonics technology made possible by recent advances in semiconductor manufacturing technology and planar waveguide fabrication. The technology's corner stone, the holographic Bragg reflector (HBR), is a slab-waveguide based, nanoscale, refractive-index structure that merges, for the first time, powerful features of holography, such as single-element spectral and spatial signal processing and overlay of multiple structures, with a highly integrated environment. As a building block for photonic circuits, the HBR's holographic signal mapping comprises a unique and novel way of on-chip signal routing and transport that is free-space-like but fully integrated. Signals propagate and overlap freely as they are imaged from active element to active element - an architecture that eliminates the need for constraining electronics-style channel-waveguides and associated space requirements and opens the door to unique integrated photonic circuits of very compact footprint. Photolithographic HBR fabrication was recently demonstrated to provide complete amplitude and phase control over individual HBR diffractive elements thus offering the powerful ability to implement almost arbitrary phase-coherent spectral filtering functions. This is enabling to a broad range of optics-on-a-chip devices including compact multiplexers, tailored passband optical filters, optical switch fabrics, spectral comparators, and correlator-based optical look-up tables.

  10. Large Deployable Reflector Technologies for Future European Telecom and Earth Observation Missions

    NASA Astrophysics Data System (ADS)

    Ihle, A.; Breunig, E.; Dadashvili, L.; Migliorelli, M.; Scialino, L.; van't Klosters, K.; Santiago-Prowald, J.

    2012-07-01

    This paper presents requirements, analysis and design results for European large deployable reflectors (LDR) for space applications. For telecommunications, the foreseeable use of large reflectors is associated to the continuous demand for improved performance of mobile services. On the other hand, several earth observation (EO) missions can be identified carrying either active or passive remote sensing instruments (or both), in which a large effective aperture is needed e.g. BIOMASS. From the European point of view there is a total dependence of USA industry as such LDRs are not available from European suppliers. The RESTEO study is part of a number of ESA led activities to facilitate European LDR development. This paper is focused on the structural-mechanical aspects of this study. We identify the general requirements for LDRs with special emphasis on launcher accommodation for EO mission. In the next step, optimal concepts for the LDR structure and the RF-Surface are reviewed. Regarding the RF surface, both, a knitted metal mesh and a shell membrane based on carbon fibre reinforced silicon (CFRS) are considered. In terms of the backing structure, the peripheral ring concept is identified as most promising and a large number of options for the deployment kinematics are discussed. Of those, pantographic kinematics and a conical peripheral ring are selected. A preliminary design for these two most promising LDR concepts is performed which includes static, modal and kinematic simulation and also techniques to generate the reflector nets.

  11. Antifungal activity of the essential oil of Illicium verum fruit and its main component trans-anethole.

    PubMed

    Huang, Yongfu; Zhao, Jianglin; Zhou, Ligang; Wang, Jihua; Gong, Youwen; Chen, Xujun; Guo, Zejian; Wang, Qi; Jiang, Weibo

    2010-10-27

    In order to identify natural products for plant disease control, the essential oil of star anise (Illicium verum Hook. f.) fruit was investigated for its antifungal activity on plant pathogenic fungi. The fruit essential oil obtained by hydro-distillation was analyzed for its chemical composition by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). trans-Anethole (89.5%), 2-(1-cyclopentenyl)-furan (0.9%) and cis-anethole (0.7%) were found to be the main components among 22 identified compounds, which accounted for 94.6% of the total oil. The antifungal activity of the oil and its main component trans-anethole against plant pathogenic fungi were determined. Both the essential oil and trans-anethole exhibited strong inhibitory effect against all test fungi indicating that most of the observed antifungal properties was due to the presence of trans-anethole in the oil, which could be developed as natural fungicides for plant disease control in fruit and vegetable preservation.

  12. Transduction for Pheromones in the Main Olfactory Epithelium Is Mediated by the Ca2+-Activated Channel TRPM5

    PubMed Central

    López, Fabián; Delgado, Ricardo; López, Roberto; Bacigalupo, Juan

    2014-01-01

    Growing evidence suggests that the main olfactory epithelium contains a subset of olfactory sensory neurons (OSNs) responding to pheromones. One candidate subpopulation expresses the calcium activated cation channel TRPM5 (transient receptor potential channel M5). Using GFP driven by the TRPM5 promoter in mice, we show that this subpopulation responds to putative pheromones, urine, and major histocompatibility complex peptides, but not to regular odors or a pheromone detected by other species. In addition, this subpopulation of TRPM5-GFP+ OSNs uses novel transduction. In regular OSNs, odorants elicit activation of the cyclic nucleotide-gated (CNG) channel, leading to Ca2+ gating of Cl− channels; in TRPM5-GFP+ OSNs, the Ca2+-activated Cl− ANO2 (anoctamin 2) channel is not expressed, and pheromones elicit activation of the CNG channel leading to Ca2+ gating of TRPM5. In conclusion, we show that OSNs expressing TRPM5 respond to pheromones, but not to regular odors through the opening of CNG channels leading to Ca2+ gating of TRPM5. PMID:24573286

  13. Optical transmitter module using polymer waveguide with fully integrated reflector mirrors

    NASA Astrophysics Data System (ADS)

    Cho, In-Kui; Ahn, Seoung-Ho; Lee, Woo-Jin; Han, Sang-Pil; Bae, Byeong-Soo; Yoon, Keun Byoung; Jeong, Myung-Yung; Park, Hyo Hoon

    2006-09-01

    The cost-effective and repeatable technology for integration of polymer multimode waveguide and out-of-plane 45° reflector mirrors is developed. This method is cost-effective, repeatable, robust, and fully compatible with the standard manufacturing processes for a 90° optical bending structure. The basic concept of the technology for integration of waveguide and out-of-plane 45° reflector mirrors is as follows; 1) The positively patterned master in order to mold waveguides is manufactured by using photolithography and Deep RIE (Reactive Ion Etching). And the master is polished to obtain 45°-inclined plane. 2) Both sides of the positively patterned master are divided into three parts by using a sawing machine. One is a center master (main-master) with a positively patterned waveguide and the others are side masters (sub-master) without a pattered waveguide. The main master and sub-master turned over get back together again. 3) The negatively patterned PDMS master to be able to mold simultaneously both waveguide and out-of-plane 45° reflector mirrors is manufactured through pouring PDMS gel into master and thermally curing the PDMS master. 4) The multimode tapered waveguides with out-of-plane 45° reflector mirrors are simultaneously embossed by using PDMS master. The UV (Ultraviolet) curable material is organic-inorganic hybrid material (HYBRIMER, core index: 1.51, clad index: 1.48). The transmitter module is constructed on a MOB. The MOB was employed for several purposes; to align optical module passively, to use as heat sinker and also to support the boards. On this MOB, 1×4 arrays of vertical-cavity surface-emitting laser (VCSEL) and Tapered Waveguide with 45° reflector mirrors are integrated. The height and width of waveguide's core are 100 μm, 60 μm respectively and the pitch is 250 μm. The transmission access lines in transmitter are designed considering differential impedance matching for high-speed operation. We measured the insertion loss of this

  14. Hybrid Deployable Foam Antennas and Reflectors

    NASA Technical Reports Server (NTRS)

    Rivellini, Tommaso; Willis, Paul; Hodges, Richard; Spitz, Suzanne

    2006-01-01

    Hybrid deployable radio antennas and reflectors of a proposed type would feature rigid narrower apertures plus wider adjoining apertures comprising reflective surfaces supported by open-cell polymeric foam structures (see figure). The open-cell foam structure of such an antenna would be compressed for compact stowage during transport. To initiate deployment of the antenna, the foam structure would simply be released from its stowage mechanical restraint. The elasticity of the foam would drive the expansion of the foam structure to its full size and shape. There are several alternatives for fabricating a reflective surface supported by a polymeric foam structure. One approach would be to coat the foam with a metal. Another approach would be to attach a metal film or a metal-coated polymeric membrane to the foam. Yet another approach would be to attach a metal mesh to the foam. The hybrid antenna design and deployment concept as proposed offers significant advantages over other concepts for deployable antennas: 1) In the unlikely event of failure to deploy, the rigid narrow portion of the antenna would still function, providing a minimum level of assured performance. In contrast, most other concepts for deploying a large antenna from compact stowage are of an "all or nothing" nature: the antenna is not useful at all until and unless it is fully deployed. 2) Stowage and deployment would not depend on complex mechanisms or actuators, nor would it involve the use of inflatable structures. Therefore, relative to antennas deployed by use of mechanisms, actuators, or inflation systems, this antenna could be lighter, cheaper, amenable to stowage in a smaller volume, and more reliable. An open-cell polymeric (e.g., polyurethane) foam offers several advantages for use as a compressible/expandable structural material to support a large antenna or reflector aperture. A few of these advantages are the following: 3) The open cellular structure is amenable to compression to a very

  15. Changes in the long-term hydrological regimes and the impacts of human activities in the main Wei River, China

    NASA Astrophysics Data System (ADS)

    Zhang, Hongbo; Huang, Qiang; Zhang, Qiang; Gu, Lei; Chen, Keyu; Yu, Qijun

    2016-03-01

    Under the combined influence of climate changes and human activities, the hydrological regime of the Wei River shows remarkable variations which have caused many issues in the Wei River in recent decades, such as a lack of freshwater, water pollution, disastrous flooding and channel sedimentation. Hence, hydrological regime changes and potential human-induced impacts have been drawing increasing attention from local government and hydrologists. This study investigates hydrological regime changes in the natural and measured runoff series at four hydrological stations on the main Wei River and quantifies features of their long-term change by analysing their historical annual and seasonal runoff data using several approaches, i.e., continuous wavelet transform, cross-wavelet, wavelet coherence, trend-free pre-whitening Mann-Kendall test and detrended fluctuation analysis. By contrasting two different analysis results between natural and measured river runoff series, the impacts of human activities on the long-term hydrological regime were investigated via the changes of spatio-temporal distribution in dominant periods, the trends and long-range memory of river runoff. The results show : (a) that periodic properties of the streamflow changes are the result of climate, referring to precipitation changes in particular, while human activities play a minor role; (b) a significant decreasing trend can be observed in the natural streamflow series along the entire main stream of the Wei River and the more serious decrease emerging in measured flow should result from human-induced influences in recent decades; and (c) continuous decreasing streamflow in the Wei River will trigger serious shortages of freshwater in the future, which may challenge the sustainability and safety of water resources development in the river basin, and should be paid great attention before 2020.

  16. From CoRoT 102899501 to the Sun. A time evolution model of chromospheric activity on the main sequence

    NASA Astrophysics Data System (ADS)

    Gondoin, P.; Gandolfi, D.; Fridlund, M.; Frasca, A.; Guenther, E. W.; Hatzes, A.; Deeg, H. J.; Parviainen, H.; Eigmüller, P.; Deleuil, M.

    2012-12-01

    Aims: The present study reports measurements of the rotation period of a young solar analogue, estimates of its surface coverage by photospheric starspots and of its chromospheric activity level, and derivations of its evolutionary status. Detailed observations of many young solar-type stars, such as the one reported in the present paper, provide insight into rotation and magnetic properties that may have prevailed on the Sun in its early evolution. Methods: Using a model based on the rotational modulation of the visibility of active regions, we analysed the high-accuracy CoRoT lightcurve of the active star CoRoT 102899501. Spectroscopic follow-up observations were used to derive its fundamental parameters. We compared the chromospheric activity level of Corot 102899501 with the R'HK index distribution vs age established on a large sample of solar-type dwarfs in open clusters. We also compared the chromospheric activity level of this young star with a model of chromospheric activity evolution established by combining relationships between the R'HK index and the Rossby number with a recent model of stellar rotation evolution on the main sequence. Results: We measure the spot coverage of the stellar surface as a function of time and find evidence for a tentative increase from 5 - 14% at the beginning of the observing run to 13-29% 35 days later. A high level of magnetic activity on Corot 102899501 is corroborated by a strong emission in the Balmer and Ca ii H and K lines (R'HK ~ -4). The starspots used as tracers of the star rotation constrain the rotation period to 1.625 ± 0.002 days and do not show evidence for differential rotation. The effective temperature (Teff = 5180 ± 80 K), surface gravity (log g = 4.35 ± 0.1), and metallicity ([M/H] = 0.05 ± 0.07 dex) indicate that the object is located near the evolutionary track of a 1.09 ± 0.12 M⊙ pre-main sequence star at an age of 23 ± 10 Myr. This value is consistent with the "gyro-age" of about 8-25 Myr

  17. Linear polarization of the radiation from active galactic nuclei and the redshift dependence of their main parameters

    NASA Astrophysics Data System (ADS)

    Silant'ev, N. A.; Piotrovich, M. Yu.; Gnedin, Yu. N.; Natsvlishvili, T. M.

    2010-11-01

    We consider the observed continuum linear polarization of extragalactic objects with various redshifts z, most of which have degrees of polarization p ≤ 10%. We propose that this polarization is due to multiple scattering of the radiation in magnetized accretion disks around the Active Galactic Nuclei (AGN; the Milne problem in an optically thick atmosphere). The structure of the accretion disks and the polarization of the emergent radiation depend on the main parameters of the AGN—the mass of the central body M BH , accretion rate dot M , magnetic field at the black-hole event horizon B H , angular momentum a *, and the explicit form of the magnetic-field distribution in the accretion disk. Theoretical expressions for the degree of polarization are averaged over all angles of the disks to the line of sight, and the resulting formula compared with the mean observed polarizations in redshift intervals Δ z = 0.25. The dependence of the observed degree of polarization and the main parameters on the redshift z is derived. The degrees of polarization of 305 objects from the catalog of Hutsemekers et al. with redshifts from zero to z = 2.25 are used for the analysis.

  18. Spectrofluorimetric determination of 3-methylflavone-8-carboxylic acid, the main active metabolite of flavoxate hydrochloride in human urine

    NASA Astrophysics Data System (ADS)

    Zaazaa, Hala E.; Mohamed, Afaf O.; Hawwam, Maha A.; Abdelkawy, Mohamed

    2015-01-01

    A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of 3-methylflavone-8-carboxylic acid as the main active metabolite of flavoxate hydrochloride in human urine. The proposed method was based on the measurement of the native fluorescence of the metabolite in methanol at an emission wavelength 390 nm, upon excitation at 338 nm. Moreover, the urinary excretion pattern has been calculated using the proposed method. Taking the advantage that 3-methylflavone-8-carboxylic acid is also the alkaline degradate, the proposed method was applied to in vitro determination of flavoxate hydrochloride in tablets dosage form via the measurement of its corresponding degradate. The method was validated in accordance with the ICH requirements and statistically compared to the official method with no significant difference in performance.

  19. Spectrofluorimetric determination of 3-methylflavone-8-carboxylic acid, the main active metabolite of flavoxate hydrochloride in human urine.

    PubMed

    Zaazaa, Hala E; Mohamed, Afaf O; Hawwam, Maha A; Abdelkawy, Mohamed

    2015-01-05

    A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of 3-methylflavone-8-carboxylic acid as the main active metabolite of flavoxate hydrochloride in human urine. The proposed method was based on the measurement of the native fluorescence of the metabolite in methanol at an emission wavelength 390 nm, upon excitation at 338 nm. Moreover, the urinary excretion pattern has been calculated using the proposed method. Taking the advantage that 3-methylflavone-8-carboxylic acid is also the alkaline degradate, the proposed method was applied to in vitro determination of flavoxate hydrochloride in tablets dosage form via the measurement of its corresponding degradate. The method was validated in accordance with the ICH requirements and statistically compared to the official method with no significant difference in performance.

  20. Analysis of Fabry-Perot optical micro-cavities based on coating-free all-silicon cylindrical Bragg reflectors.

    PubMed

    Malak, Maurine; Gaber, Noha; Marty, Frédéric; Pavy, Nicolas; Richalot, Elodie; Bourouina, Tarik

    2013-01-28

    We study the behavior of Fabry-Perot micro-optical resonators based on cylindrical reflectors, optionally combined with cylindrical lenses. The core of the resonator architecture incorporates coating-free, all-silicon, Bragg reflectors of cylindrical shape. The combined effect of high reflectance and light confinement produced by the reflectors curvature allows substantial reduction of the energy loss. The proposed resonator uses curved Bragg reflectors consisting of a stack of silicon-air wall pairs constructed by micromachining. Quality factor Q ~1000 was achieved on rather large cavity length L = 210 microns, which is mainly intended to lab-on-chip analytical experiments, where enough space is required to introduce the analyte inside the resonator. We report on the behavioral analysis of such resonators through analytical modeling along with numerical simulations supported by experimental results. We demonstrate selective excitation of pure longitudinal modes, taking advantage of a proper control of mode matching involved in the process of coupling light from an optical fiber to the resonator. For the sake of comparison, insight on the behavior of Fabry-Perot cavity incorporating a Fiber-Rod-Lens is confirmed by similar numerical simulations.

  1. Large deployable antenna reflector trimming mechanism (LDA-RTM)

    NASA Astrophysics Data System (ADS)

    Domingo, Miguel; Vázquez, Jorge

    2003-09-01

    Future projects dealing with radars or telecommunications require deployable antennas. ESA Contract no. 15230 for the "Development of Large Deployable Antenna Reflector for Advanced Mobile Communication" has the objective of developing this critical technology in Europe for the commercial market. The Reflector Trimming Mechanism (RTM) allows the fine adjustment of the huge Reflector Dish (12 meters projected aperture diameter) in such a way to recover the mispointing induced by all sources inclusive of the S/C, the Antenna Arm, the feed and the Reflector. The RTM design is modular and allows its implementation in different reflector types and dimensions changing the distance between movable and fixed points and the lateral stiffener. In each linear actuator, it is implemented a device which is able to decouple the top and the bottom part. This is required because of imposed displacements of the interfaces during launch. The decoupling device is latched before starting normal operating condition. It is actuated with the same stepper motor used for trimming. The RTM has been designed to be operated with the electronic box already developed for moving the Antenna Pointing Mechanism in Hispasat 1-C.

  2. A computer program to calculate radiation properties of reflector antennas

    NASA Technical Reports Server (NTRS)

    Agrawal, P. K.

    1978-01-01

    A computer program to calculate the radiation properties of the reflector antennas is presented. It can be used for paraboloidal, spherical, or ellipsoidal reflector surfaces and is easily modified to handle any surface that can be expressed analytically. The program is general enough to allow any arbitrary location and pointing angle for the feed antenna. The effect of blockage due to the feed horn is also included in the computations. The computer program is based upon the technique of tracing the rays from the feed antenna to the reflector to an aperture plane. The far field radiation properties are then calculated by performing a double integration over the field points in the aperture plane. To facilitate the computation of double intergral, the field points are first aligned along the equispaced straight lines in the aperture plane. The computation time is relatively insensitive to the absolute size of the aperture and even though no limits on the largest reflector size have been determined, the program was used for reflector diameters of 1000 wavelenghts.

  3. Computer prediction of large reflector antenna radiation properties

    NASA Technical Reports Server (NTRS)

    Botula, A.

    1980-01-01

    A FORTRAN program for calculating reflector antenna radiation patterns was rewritten and extended to include reflectors composed of a number of panels. These individual panels must be analytic surfaces. The theoretical foundation for the program is as follows: Geometrical optics techniques are used to trace rays from a feed antenna to the reflector surface and back to a mathematical plane just in front of the reflector. The resulting tangential electric field distribution, assumed to be the only source of forward radiation, is integrated numerically to calculate the radiation pattern for a desired set of angles. When the reflector is composed of more than one panel, each panel is treated as a separated antenna, the ray-tracing procedure and integration being repeated for each panel. The results of the individual aperture plane integrations are stored and summed to yield the relative electric field strength over the angles of interest. An example and several test cases are included to demonstrate the use of the program and verify the new method of computation.

  4. Antiviral activity of the Lippia graveolens (Mexican oregano) essential oil and its main compound carvacrol against human and animal viruses

    PubMed Central

    Pilau, Marciele Ribas; Alves, Sydney Hartz; Weiblen, Rudi; Arenhart, Sandra; Cueto, Ana Paula; Lovato, Luciane Teresinha

    2011-01-01

    Mexican oregano (Lippia graveolens) is a plant found in Mexico and Central America that is traditionally used as a medicinal herb. In the present study, we investigated the antiviral activity of the essential oil of Mexican oregano and its major component, carvacrol, against different human and animal viruses. The MTT test (3–4,5-dimethythiazol-2yl)-2,5-diphenyl tetrazolium bromide) was conducted to determine the selectivity index (SI) of the essential oil, which was equal to 13.1, 7.4, 10.8, 9.7, and 7.2 for acyclovir-resistant herpes simplex virus type 1 (ACVR-HHV-1), acyclovir-sensitive HHV-1, human respiratory syncytial virus (HRSV), bovine herpesvirus type 2 (BoHV-2), and bovine viral diarrhoea virus (BVDV), respectively. The human rotavirus (RV) and BoHV-1 and 5 were not inhibited by the essential oil. Carvacrol alone exhibited high antiviral activity against RV with a SI of 33, but it was less efficient than the oil for the other viruses. Thus, Mexican oregano oil and its main component, carvacrol, are able to inhibit different human and animal viruses in vitro. Specifically, the antiviral effects of Mexican oregano oil on ACVR-HHV-1 and HRSV and of carvacrol on RV justify more detailed studies. PMID:24031796

  5. Experimental Results of Plasma Induced EMI Effects in a Reflector Antenna System

    NASA Astrophysics Data System (ADS)

    Bandinelli, M.; Pandolfo, L.; Sarri, A.; Fittipaldi, D. A.; Pawlak, H.; Marliani, F.

    2012-05-01

    This paper presents measurement results of the electromagnetic interference (EMI) caused by the plasma plume of ion thrusters firing through the RF beam of reflector antennas. The EMI effect consists mainly in the introduction of discrete spurious modulation products on the RF carrier thus degrading spectral purity. The measurements were carried out on a mockup which is geometrically representative of the actual SGEO spacecraft design. The mockup and the acquisition system were specifically designed to allow RF measurements inside a metallic vacuum chamber. Three ion thrusters were characterised during the test campaign: SPT-100, HEMP-T, PPS-1350.

  6. Potential anxiolytic- and antidepressant-like effects of salvinorin A, the main active ingredient of Salvia divinorum, in rodents

    PubMed Central

    Braida, Daniela; Capurro, Valeria; Zani, Alessia; Rubino, Tiziana; Viganò, Daniela; Parolaro, Daniela; Sala, Mariaelvina

    2009-01-01

    Background and purpose: Drugs targeting brain κ-opioid receptors produce profound alterations in mood. In the present study we investigated the possible anxiolytic- and antidepressant-like effects of the κ-opioid receptor agonist salvinorin A, the main active ingredient of Salvia divinorum, in rats and mice. Experimental approach: Experiments were performed on male Sprague-Dawley rats or male Albino Swiss mice. The anxiolytic-like effects were tested by using the elevated plus maze, in rats. The antidepressant-like effect was estimated through the forced swim (rats) and the tail suspension (mice) test. κ-Opioid receptor involvement was investigated pretreating animals with the κ-opioid receptor antagonist, nor-binaltorphimine (1 or 10 mg·kg−1), while direct or indirect activity at CB1 cannabinoid receptors was evaluated with the CB1 cannabinoid receptor antagonist, N-(piperidin-1-yl) -5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251, 0.5 or 3 mg·kg−1), binding to striatal membranes of naïve rats and assay of fatty acid amide hydrolase in prefrontal cortex, hippocampus and amygdala. Key results: Salvinorin A, given s.c. (0.001–1000 µg·kg−1), exhibited both anxiolytic- and antidepressant-like effects that were prevented by nor-binaltorphimine or AM251 (0.5 or 3 mg·kg−1). Salvinorin A reduced fatty acid amide hydrolase activity in amygdala but had very weak affinity for cannabinoid CB1 receptors. Conclusions and implications: The anxiolytic- and antidepressant-like effects of Salvinorin A are mediated by both κ-opioid and endocannabinoid systems and may partly explain the subjective symptoms reported by recreational users of S. divinorum. PMID:19422370

  7. Search radar reflector antennas with extremely low sidelobes

    NASA Astrophysics Data System (ADS)

    Carlsson, E.; Derneryd, A.; Karlsson, E. R.; Larsson, J.-O.

    Several different search radar reflector antennas have been developed for varying elevation coverage and frequency requirements. The trend has been towards extremely low azimuth sidelobes. This paper treats electrical and mechanical design of such antennas including results achieved using computer aided optimization procedures (CAD). The definition of reflector shape and contour and the associated electrical performance, are presented. Furthermore, theoretical analyses concerning reflector surface imperfections and frequency dependence are given. Mechanical analyses for minimizing mass and deformations at high wind velocities, by means of computer simulations, wind tunnel tests and careful material selection are also presented. The antennas are manufactured in a sandwich GFRP construction on precision moulds which have been milled using NC-machines. Input data tapes are generated directly from the theoretical design computations (CAM). These antennas have been tested at a computer controlled test range and sidelobe performance down to -60 dB has been demonstrated.

  8. Large-Scale All-Dielectric Metamaterial Perfect Reflectors

    SciTech Connect

    Moitra, Parikshit; Slovick, Brian A.; li, Wei; Kravchencko, Ivan I.; Briggs, Dayrl P.; Krishnamurthy, S.; Valentine, Jason

    2015-05-08

    All-dielectric metamaterials offer a potential low-loss alternative to plasmonic metamaterials at optical frequencies. In this paper, we take advantage of the low absorption loss as well as the simple unit cell geometry to demonstrate large-scale (centimeter-sized) all-dielectric metamaterial perfect reflectors made from silicon cylinder resonators. These perfect reflectors, operating in the telecommunications band, were fabricated using self-assembly based nanosphere lithography. In spite of the disorder originating from the self-assembly process, the average reflectance of the metamaterial perfect reflectors is 99.7% at 1530 nm, surpassing the reflectance of metallic mirrors. Moreover, the spectral separation of the electric and magnetic resonances can be chosen to achieve the required reflection bandwidth while maintaining a high tolerance to disorder. Finally, the scalability of this design could lead to new avenues of manipulating light for low-loss and large-area photonic applications.

  9. Integrated structural electromagnetic optimization of large space antenna reflectors

    NASA Technical Reports Server (NTRS)

    Padula, S. L.; Adelman, H. M.; Bailey, M. C.

    1987-01-01

    The requirements for extremely precise and powerful large space antenna reflectors have motivated the development of a procedure for shape control of the reflector surface. A mathematical optimization procedure has been developed which improves antenna performance while minimizing necessary shape correction effort. In contrast to previous work which proposed controlling the rms distortion error of the surface thereby indirectly improving antenna performance, the current work includes electromagnetic (EM) performance calculations as an integral part of the control procedure. The application of the procedure to a radiometer design with a tetrahedral truss backup structure demonstrates the potential for significant improvement. The results indicate the benefit of including EM performance calculations in procedures for shape control of large space antenna reflectors.

  10. Integrated structure electromagnetic optimization of large space antenna reflectors

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Adelman, Howard M.; Bailey, M. C.

    1987-01-01

    The requirements for extremely precise and powerful large space antenna reflectors have motivated the development of a procedure for shape control of the reflector surface. A mathematical optimization procedure has been developed which improves antenna performance while minimizing necessary shape correction effort. In contrast to previous work which proposed controlling the rms distortion error of the surface thereby indirectly improving antenna performance, the current work includes electromagnetic (EM) performance calculations as an integral of the control procedure. The application of the procedure to a radiometer design with a tetrahedral truss backup structure demonstrates the potential for significant improvement. The results indicate the benefit of including EM performance calculations in procedures for shape control of large space antenna reflectors.

  11. Large-Scale All-Dielectric Metamaterial Perfect Reflectors

    DOE PAGES

    Moitra, Parikshit; Slovick, Brian A.; li, Wei; ...

    2015-05-08

    All-dielectric metamaterials offer a potential low-loss alternative to plasmonic metamaterials at optical frequencies. In this paper, we take advantage of the low absorption loss as well as the simple unit cell geometry to demonstrate large-scale (centimeter-sized) all-dielectric metamaterial perfect reflectors made from silicon cylinder resonators. These perfect reflectors, operating in the telecommunications band, were fabricated using self-assembly based nanosphere lithography. In spite of the disorder originating from the self-assembly process, the average reflectance of the metamaterial perfect reflectors is 99.7% at 1530 nm, surpassing the reflectance of metallic mirrors. Moreover, the spectral separation of the electric and magnetic resonances canmore » be chosen to achieve the required reflection bandwidth while maintaining a high tolerance to disorder. Finally, the scalability of this design could lead to new avenues of manipulating light for low-loss and large-area photonic applications.« less

  12. Illumination from space with orbiting solar-reflector spacecraft

    NASA Technical Reports Server (NTRS)

    Canady, J. E., Jr.; Allen, J. L., Jr.

    1982-01-01

    The feasibility of using orbiting mirrors to reflect sunlight to Earth for several illumination applications is studied. A constellation of sixteen 1 km solar reflector spacecraft in geosynchronous orbit can illuminate a region 333 km in diameter to 8 lux, which is brighter than most existing expressway lighting systems. This constellation can serve one region all night long or can provide illumination during mornings and evenings to five regions across the United States. Preliminary cost estimates indicate such an endeavor is economically feasible. The studies also explain how two solar reflectors can illuminate the in-orbit nighttime operations of Space Shuttle. An unfurlable, 1 km diameter solar reflector spacecraft design concept was derived. This spacecraft can be packaged in the Space, Shuttle, transported to low Earth orbit, unfurled, and solar sailed to operational orbits up to geosynchronous. The necessary technical studies and improvements in technology are described, and potential environmental concerns are discussed.

  13. Mechanisms Underlying the Antinociceptive, Antiedematogenic, and Anti-Inflammatory Activity of the Main Flavonoid from Kalanchoe pinnata

    PubMed Central

    Ferreira, Raquel Teixeira; Coutinho, Marcela Araújo Soares; Malvar, David do Carmo; Costa, Elson Alves; Florentino, Iziara Ferreira; Costa, Sônia Soares; Vanderlinde, Frederico Argollo

    2014-01-01

    Kalanchoe pinnata (KP) is popularly used for treating inflammatory diseases. This study investigated the antinociceptive, antiedematogenic, and anti-inflammatory potential of the subcutaneous administration of KP flower aqueous extract (KPFE), its ethyl acetate (EtOAcF) and butanol (BuOHF) fractions, and the main KP flavonoid [quercetin 3-O-α-L-arabinopyranosyl (1 → 2) α-L-rhamnopyranoside] (KPFV) in mice, as well as its possible mechanisms of action. KPFE (30–300 mg/kg) and KPFV (1–10 mg/kg) inhibited the acetic acid-induced writhing (ID50 = 164.8 and 9.4 mg/kg, resp.). KPFE (300 mg/kg), EtOAcF (12 mg/kg), BuOHF (15 mg/kg), or KPFV (0.3–3.0 mg/kg) reduced leukocyte migration on carrageenan-induced pleurisy (ID50 = 2.0 mg/kg for KPFV). KPFE (3–30 mg/kg) and KPFV (0.3–3.0 mg/kg) reduced the croton oil-induced ear edema (ID50 = 4.3 and 0.76 mg/kg, resp.). KPFE and KPFV reduced the TNF-α concentration in the pleural exudates on carrageenan-induced pleurisy test. Moreover, KPFV inhibited COX-1 (IC50 = 22.1 μg/mL) and COX-2 (IC50 > 50 μg/mL). The selectivity index (COX-1IC50/COX-2IC50) was <0.44. These results indicate that KPFE and KPFV produced antinociceptive, antiedematogenic, and anti-inflammatory activities through COX inhibition and TNF-α reduction, revealing that the main flavonoid in KP flowers and leaves plays an important role in the ethnomedicinal use of the plant. PMID:25580151

  14. Can We Forecast 1-Month Span Aftershock Activity from the First Day Data after the Main Shock?

    NASA Astrophysics Data System (ADS)

    Omi, T.; Ogata, Y.; Hirata, Y.; Aihara, K.

    2014-12-01

    A large earthquake triggers persistent aftershock activity in and near the focal region. Thus, intermediate term forecasting of aftershocks at its earlier stage is important for mitigating seismic risks. A main difficulty for the early forecasting is the substantial incompleteness of early aftershock data. To deal with such incomplete data, we have developed a statistical model of the incomplete data, enabling us to obtain the immediate estimate of the forecasting models from incomplete data [1, 2]. Another difficulty for the intermediate term forecasting is that we have to determine the parameter values of the forecasting models with high accuracy, because even a small bias in the parameter values can lead to a significant bias of the forecasting in intermediate term. However such accurate estimation is quite difficult at the early stage, especially using the early and incomplete data. Here we present a Bayesian forecasting method by using the epidemic-type aftershock sequence (ETAS) model. The Bayesian forecasting considers not only the best parameter values such as the maximum likelihood estimates or maximum a posteriori estimates but also the estimation uncertainty of the parameter values. By analyzing aftershock sequences in Japan, we show the forecasting performances of the intermediate-term aftershocks can be significantly improved by considering the estimation uncertainty of the ETAS model [3]. Furthermore, we discuss the impact of the modeling of the magnitude frequency distribution of detected aftershocks within a day span on the forecasting of large aftershocks. [1] T. Omi, Y. Ogata, Y. Hirata and K. Aihara, "Forecasting large aftershocks within one day after the main shock", Scientific Reports 3, 2218 (2013). [2] T. Omi, Y. Ogata, Y. Hirata and K. Aihara, "Estimating the ETAS model from an early aftershock sequence", Geophysical Research Letters 41, 850 (2014). [3] T. Omi, Y. Ogata, Y. Hirata and K. Aihara, "Intermediate-term forecasting of aftershocks

  15. Transformable reflector structure with V-folding rods

    NASA Astrophysics Data System (ADS)

    Tserodze, Sh.; Prowald, J. Santiago; Gogilashvili, V.; Chkhikvadze, K.

    2016-12-01

    A new design of space deployable reflector is presented. In particular, we consider closed-chain system (with central network), which as a result of transformation reaches the conical shape. In conformity with the technical specifications, individual parts of the system perform the simultaneous motion in the radial and axial directions. The main motion of the system produced by geometric constraints is studied, i.e., we consider the degree of structural motion. Parametric degrees of freedom caused by technological errors, modes of motion, types of load or deployment velocity are not taken into consideration at this stage. A peculiar feature of the deployable structure presented in the paper is that, as compared with analogous structures, for connecting the sections with one another there is no need of using synchronization devices in both—upper and lower kinematic chains simultaneously. This structural mechanism is a differential lever mechanism, the driving elements of which enable us to obtain the desired law of motion of every characteristic link. The kinematic model represents the whole system. Therefore, we can construct the function of position of the lever mechanism and also the kinematic functions of transmission. For the preliminary investigation of the structure and making possible changes in it, two mathematical models have been constructed by means of the ANSYS software using the Ansys Parametric Design Language. The degrees of freedom of the hinges are simulated in local coordinate systems and are as much as possible approximated to the real model. Calculations are performed for various kinds of loads and appropriate results are obtained.

  16. Novel array-feed distortion compensation techniques for reflector antennas

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Yahya

    1991-01-01

    Degradation of antenna performance by reflector surface distortion, which lowers gain and increases sidelobe levels, is addressed. Distortion compensation concepts based on the applications of properly matched array feeds are presented. Results of conceptual developments, numerical simulations, and measurement verifications are presented in support of this approach, with particular attention to the measurement technique. It is shown that the concept is most useful for overcoming the deterioration effects of slowly varying surface distortions, which would make the method very useful for future large space and ground antennas. It is further shown that for a typical, slowly varying thermal or gravitational surface distortion, a 19-element array feed can improve the reflector performance considerably.

  17. Caustic Singularities Of High-Gain, Dual-Shaped Reflectors

    NASA Technical Reports Server (NTRS)

    Galindo, Victor; Veruttipong, Thavath W.; Imbriale, William A.; Rengarajan, Sambiam

    1991-01-01

    Report presents study of some sources of error in analysis, by geometric theory of diffraction (GTD), of performance of high-gain, dual-shaped antenna reflector. Study probes into underlying analytic causes of singularity, with view toward devising and testing practical methods to avoid problems caused by singularity. Hybrid physical optics (PO) approach used to study near-field spillover or noise-temperature characteristics of high-gain relector antenna efficiently and accurately. Report illustrates this approach and underlying principles by presenting numerical results, for both offset and symmetrical reflector systems, computed by GTD, PO, and PO/GO methods.

  18. Static and dynamic characteristics of large deployable space reflectors

    NASA Technical Reports Server (NTRS)

    El-Raheb, M.; Wagner, P.

    1981-01-01

    A linear numerical model of the structural characteristics of deployable reflectors was developed. Due to cyclic symmetry of the reflector structure about its axis, only one of many segments is modeled using finite elements. The succeeding segments satisfy continuity of displacement and slope at the interface between consecutive segments. This process leads to (N/2+1) static or dynamic problems of smaller order and bandwidth where N is the number of segments. The solution of each reduced problem leads to motions having a distinct circumferential wave number. The dynamic coupling to the feed support structure is studied adopting modal synthesis.

  19. Dichroic Bragg reflectors based on birefringent porous silicon

    SciTech Connect

    Diener, J.; Kunzner, N.; Kovalev, D.; Gross, E.; Timoshenko, V. Yu.; Polisski, G.; Koch, F.

    2001-06-11

    Multilayers of anisotropically nanostructured silicon (Si) have been fabricated and studied by polarization-resolved reflection measurements. Alternating layers having different refractive indices exhibit additionally a strong in-plane anisotropy of their refractive index (birefringence). Therefore, a stack of layers, acting as a distributed Bragg reflector, has two distinct reflection bands, depending on the polarization of the incident linearly polarized light. This effect is governed by a three-dimensional (in-plane and in-depth) variation of the refractive index. These structures can yield optical effects which are difficult to achieve with conventional Bragg reflectors. {copyright} 2001 American Institute of Physics.

  20. Coupled Elastic-Thermal Dynamics of Deployable Mesh Reflectors

    NASA Technical Reports Server (NTRS)

    Shi, H.; Yang, B.; Thomson, M.; Fang, H.

    2011-01-01

    This paper presents a coupled elastic-thermal dynamic model and a quasi-static strategy on the analysis of the reflector dynamics in the space mission. The linearized model, its natural frequencies and mode shapes are then derived upon the nonlinear static equilibrium of the structure. The numerical example is provided to fully adapt the strategy and investigate the dynamic behaviors of the structure. Finally the proposed method is applied on the sample of the deployable mesh reflector and the simulation results are presented. The research work delivered in the paper will be used to design the feedback surface in future.

  1. New Developments in Large High Performance Shaped Reflectors

    NASA Astrophysics Data System (ADS)

    Abegg, C.; Baril, S.

    2002-01-01

    The large shaped reflectors, currently designed and manufactured at EADS LAUNCH VEHICLES, belong to a new generation of highly precise, highly stable and low mass reflectors for C/Ku-band and up to Ka-band missions. The previous EADS LAUNCH VEHICLES flight proven design was the one presented in the past at IAF and especially in 1994 and 1995, which was already at his time the in-orbit largest (3.5m x 2.6m) rigid reflector in the world for C/Ku-band missions. Operators require higher and higher performances for telecommunication antenna. And since the antenna performances are very dependent on the reflector ones, several developments of a new generation of large shaped reflectors started in the late 1990's. The first development consists in a new concept which particularly enhances the manufacturing easiness, the manufacturing distortion performances, the in-orbit distortion performances, the mass, the versatility versus a late change of coverage and versus implementation on different platforms. An extensive qualification test campaign has been successfully achieved in 2001, with outstanding performances: 30% mass gain and 50% gain of manufacturing and in-orbit accuracy with respect to previous 1995's design for the largest 3.5m x 2.6m reflectors. In parallel, developments have been led at EADS LAUNCH VEHICLES for large Ka-band mission antenna reflectors. These developments include single and dual shell reflectors with diameters up to 1.8 m. Furthermore, antenna requirements have recently led to more and more shaped profiles to fulfil RF needs. EADS LAUNCH VEHICLES has then started a development to verify the capability to manufacture very small curvature radius around 30mm, in order to provide the best product for the satellite missions. All the necessary analyses and material/processes characterisation tests have been carried out for these developments. Qualification tests have been performed or are under progress in profile measurements, sine vibration, acoustic

  2. PAHs in sediment cores at main river estuaries of Chaohu Lake: implication for the change of local anthropogenic activities.

    PubMed

    Ren, Chen; Wu, Yaketon; Zhang, Shuo; Wu, Liang-Liang; Liang, Xiao-Guo; Chen, Tian-Hu; Zhu, Cheng-Zhu; Sojinu, Samuel O; Wang, Ji-Zhong

    2015-02-01

    In the present study, 28 polycyclic aromatic hydrocarbons (PAHs) were investigated in four sediment cores collected from the main river estuaries of Chaohu Lake, one of the severely polluted lakes in China. The results indicate that elevated concentrations of total PAHs (Σ28PAH) were found in the samples from the estuary of Nanfei River (ENF), considering BaP-based total toxicity equivalent (TEQ-BaP) and toxic unit (TU) results; there are potential adverse environmental implications. The total organic carbon (TOC) played an important role on the accumulation of PAHs at ENF and the estuary of Tongyang River (ETY). The predominant PAHs are high molecular weight (HMW) homologous for all samples; as a result, industrial wastewater from a steel company is expectedly the key source of PAHs in ENF, while coke consumption would be the important source of PAHs at other three sampling sites. Vertical distribution of PAHs in the sediment cores could be explained by the local social and economic activities. Furthermore, a minor variation of PAH composition in the sediment core could be justified by the stable structure of energy consumption in the Anhui Province. These results justify the need for further enhancement of industrial wastewater treatment and development of renewable energies which are the key factors on the control of PAH pollution in China.

  3. Photosynthetic carbon reduction and carbon oxidation cycles are the main electron sinks for photosystem II activity during a mild drought.

    PubMed

    Cornic, Gabriel; Fresneau, Chantal

    2002-06-01

    Stomatal closure can explain the inhibition of net CO2 uptake by a leaf subjected to a mild drought: the photosynthetic apparatus appears resistant to lack of water. Changes in both the water content of leaves maintained in a constant environment and the ambient CO2 molar fraction during measurements on well-hydrated leaves lead to similar effects on net CO2 uptake and whole chain electron transport as estimated by leaf chlorophyll fluorescence measurements. In particular, it is shown that photosystem II (PSII) functioning and its regulation are not qualitatively changed during desiccation and that the variations in PSII photochemistry can simply be understood by changes in substrate availability in this condition. Moreover, an analysis of the literature shows that when inhibition of net CO2 uptake by C3 leaves under drought (Phaseolus vulgaris L., Helianthus annus L. and Solanum tuberosum L.) was lower than 80 %, elevated CO2 completely restored the photosynthetic capacity. The CO2 molar fraction in the chloroplasts declines as stomata close in drying leaves. As a consequence, in C3 plants, ribulose-1,5-bisphosphate oxygenation increases and becomes the main sink for photosynthetic electrons. Depending on the prevailing photon flux density, the O2 uptake through photorespiratory activity can entirely replace carbon dioxide as an electron acceptor, or not. The rate of the Mehler reaction remains low and unchanged during desiccation. However, drought could also involve CO2-sensitive modification of the photosynthetic metabolism depending on plant growth conditions and possibly also on plant species.

  4. Field trials on the repellent activity of four plant products against mainly Mansonia population in western Ethiopia.

    PubMed

    Hadis, Mamuye; Lulu, Mesfin; Mekonnen, Yared; Asfaw, Teffera

    2003-03-01

    The repellent activity of essential oils of lemon eucalyptus (Eucalyptus maculata citrodion), rue (Ruta chalepensis), oleoresin of pyrethrum (Chrysanthemum cinerariaefolium) and neem (Azadiracta indica) have been field tested as 40%, 50% and 75% solutions in coconut oil against populations of mosquitoes consisting mainly of Mansonia in Gambella, western Ethiopia. A latin square design was used to randomize the test subjects for possible individual differences for mosquito attraction. Repellency was evaluated as the percentage protection. Deet was included in the study for comparison. All the plant products manifested repellency. At 50% concentration at which the highest repellency was recorded the protection was 91.6%, 87.0%, 96.0%, 97.9% for rue, neem, pyrethrum and deet, respectively. The essential oil of lemon eucalyptus was not tried at this concentration. At a 40% concentration deet, lemon eucalyptus and pyrethrum were significantly (p < 0.05) more effective than rue and neem. At a 50% concentration, deet and pyrethrum were significantly better (p < 0.05) than rue and neem. At a 75% concentration concentration, deet and lemon eucalypus performed significantly better (p < 0.05) than pyrethrum and neem. The difference between pyrethrum and neem was also significant (p < 0.01).

  5. 49 CFR Appendix B to Part 224 - Reflectorization Implementation Compliance Report

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Reflectorization Implementation Compliance Report B Appendix B to Part 224 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION REFLECTORIZATION OF RAIL FREIGHT...

  6. 49 CFR Appendix B to Part 224 - Reflectorization Implementation Compliance Report

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Reflectorization Implementation Compliance Report B Appendix B to Part 224 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION REFLECTORIZATION OF RAIL FREIGHT...

  7. Main factors controlling microbial community structure, growth and activity after reclamation of a tailing pond with aided phytostabilization

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Acosta, José A.; Martínez-Martínez, Silvia; Faz, Ángel; Bååth, Erland

    2015-04-01

    Reclamation on bare tailing ponds has the potential to represent soil genesis in Technosols favoring the understanding of the changes of microbial communities and function. In this study we used phytostabilization aided with calcium carbonate and pig slurry/manure to reclaim an acidic bare tailing pond with the aim of investigating the effect of amending and different species on microbial community structure and function. We sampled after two years of amending and planting: unamended tailing soil (UTS), non-rhizospheric amended tailing soil (ATS), rhizospheric soil from four species, and non-rhizospheric native forest soil (NS), which acted as reference. The application of amendments increased pH up to neutrality, organic carbon (Corg), C/N and aggregate stability, while decreased salinity and heavy metals availability. No effect of rhizosphere was observed on physicochemical properties, metals immobilization and microbial community structure and function. To account for confounding effects due to soil organic matter, microbial properties were expressed per Corg. The high increments in pH and Corg have been the main factors driving changes in microbial community structure and function. Bacterial biomass was higher in UTS, without significant differences among the rest of soils. Fungal biomass followed the trend UTS < ATS = rhizospheric soils < NS. Bacterial growth increased and fungal growth decreased with increasing pH, despite the high availability of metals at low pH. Enzyme activities were lower in UTS, being β-glucosidase and β-glucosaminidase activities highly correlated with bacterial growth. Microbial activities were not correlated with the exchangeable fraction of heavy metals, indicating that microbial function is not strongly affected by these metals, likely due to the efficiency of the reclamation procedure to reduce metals toxicity. Changes in microbial community composition were largely explained by changes in pH, heavy metals availability and Corg

  8. Step-Stress Accelerated Degradation Testing for Solar Reflectors: Preprint

    SciTech Connect

    Jones, W.; Elmore, R.; Lee, J.; Kennedy, C.

    2011-09-01

    To meet the challenge to reduce the cost of electricity generated with concentrating solar power (CSP) new low-cost reflector materials are being developed including metalized polymer reflectors and must be tested and validated against appropriate failure mechanisms. We explore the application of testing methods and statistical inference techniques for quantifying estimates and improving lifetimes of concentrating solar power (CSP) reflectors associated with failure mechanisms initiated by exposure to the ultraviolet (UV) part of the solar spectrum. In general, a suite of durability and reliability tests are available for testing a variety of failure mechanisms where the results of a set are required to understand overall lifetime of a CSP reflector. We will focus on the use of the Ultra-Accelerated Weathering System (UAWS) as a testing device for assessing various degradation patterns attributable to accelerated UV exposure. Depending on number of samples, test conditions, degradation and failure patterns, test results may be used to derive insight into failure mechanisms, associated physical parameters, lifetimes and uncertainties. In the most complicated case warranting advanced planning and statistical inference, step-stress accelerated degradation (SSADT) methods may be applied.

  9. Advanced reflector characterization with ultrasonic phased arrays in NDE applications.

    PubMed

    Wilcox, Paul D; Holmes, Caroline; Drinkwater, Bruce W

    2007-08-01

    Ultrasonic arrays are increasingly widely used in nondestructive evaluation (NDE) due to their greater flexibility and potentially superior performance compared to conventional monolithic probes. The characterization of small defects remains a challenge for NDE and is of great importance for determining the impact of a defect on the integrity of a structure. In this paper, a technique for characterizing reflectors with subwavelength dimensions is described. This is achieved by post-processing the complete data set of time traces obtained from an ultrasonic array using two algorithms. The first algorithm is used to obtain information about reflector orientation and the second algorithm is used to distinguish between point-like reflectors that reflect uniformly in all directions and specular reflectors that have distinct orientations. Experimental results are presented using a commercial 64-element, 5-MHZ array on two aluminum test specimens that contain a number of machined slots and side-drilled holes. The results show that the orientation of 1-mm-long slots can be determined to within a few degrees and that the signals from 1-mm-long slots can be distinguished from that from a 1-mm-diameter circular hole. Techniques for quantifying both the orientation and the specularity of measured signals are presented and the effect of processing parameters on the accuracy of results is discussed.

  10. Long-Life Self-Renewing Solar Reflector Stack

    DOEpatents

    Butler, Barry Lynn

    1997-07-08

    A long-life solar reflector includes a solar collector substrate and a base layer bonded to a solar collector substrate. The first layer includes a first reflective layer and a first acrylic or transparent polymer layer covering the first reflective layer to prevent exposure of the first reflective layer. The reflector also includes at least one upper layer removably bonded to the first acrylic or transparent polymer layer of the base layer. The upper layer includes a second reflective layer and a second acrylic or transparent polymer layer covering the second reflective layer to prevent exposure of the second reflective layer. The upper layer may be removed from the base reflective layer to expose the base layer, thereby lengthening the useful life of the solar reflector. A method of manufacturing a solar reflector includes the steps of bonding a base layer to a solar collector substrate, wherein the base reflective layer includes a first reflective layer and a first transparent polymer or acrylic layer covering the first reflective layer; and removably bonding a first upper layer to the first transparent polymer or acrylic layer of the base layer. The first upper layer includes a second reflective layer and a second transparent polymer or acrylic layer covering the second reflective layer to prevent exposure of the second reflective layer.

  11. Detail of 94' lowband reflector screen posts, note the concrete ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of 94' low-band reflector screen posts, note the concrete curb and vertical wires between posts, view facing north northeast - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  12. Detail of dipole antenna element (right) and 94' lowband reflector ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of dipole antenna element (right) and 94' low-band reflector screen poles (left), note the guy wires from the antenna element, view facing north northeast - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  13. Beam spoiling a reflector antenna with conducting shim.

    SciTech Connect

    Doerry, Armin Walter

    2012-12-01

    A horn-fed dish reflector antenna has characteristics including beam pattern that are a function of its mechanical form. The beam pattern can be altered by changing the mechanical configuration of the antenna. One way to do this is with a reflecting insert or shim added to the face of the original dish.

  14. Process sequence produces strong, lightweight reflectors of excellent quality

    NASA Technical Reports Server (NTRS)

    Reader, A. F.; Russell, W. E.; Werner, E. A.

    1967-01-01

    Large compound curved surfaces for collecting and concentrating radiation are fabricated by the use of several common machining and forming processes. Lightweight sectors are assembled into large reflectors. With this concept of fabrication, integrally stiffened reflective sectors up to 25 square feet in area have been produced.

  15. Geometry adaptive control of a composite reflector using PZT actuator

    NASA Astrophysics Data System (ADS)

    Lan, Lan; Jiang, Shuidong; Zhou, Yang; Fang, Houfei; Tan, Shujun; Wu, Zhigang

    2015-04-01

    Maintaining geometrical high precision for a graphite fiber reinforced composite (GFRC) reflector is a challenging task. Although great efforts have been placed to improve the fabrication precision, geometry adaptive control for a reflector is becoming more and more necessary. This paper studied geometry adaptive control for a GFRC reflector with piezoelectric ceramic transducer (PZT) actuators assembled on the ribs. In order to model the piezoelectric effect in finite element analysis (FEA), a thermal analogy was used in which the temperature was applied to simulate the actuation voltage, and the piezoelectric constant was mimicked by a Coefficient of Thermal Expansion (CTE). PZT actuator's equivalent model was validated by an experiment. The deformations of a triangular GFRC specimen with three PZT actuators were also measured experimentally and compared with that of simulation. This study developed a multidisciplinary analytical model, which includes the composite structure, thermal, thermal deformation and control system, to perform an optimization analysis and design for the adaptive GFRC reflector by considering the free vibration, gravity deformation and geometry controllability.

  16. Prelaunch testing of the GEOS-3 laser reflector array

    NASA Technical Reports Server (NTRS)

    Minott, P. O.; Fitzmaurice, M. W.; Abshire, J. B.; Rowe, H. E.

    1978-01-01

    The prelaunch testing performed on the Geos-3 laser reflector array before launch was used to determine the lidar cross section of the array and the distance of the center of gravity of the satellite from the center of gravity of reflected laser pulses as a function of incidence angle. Experimental data are compared to computed results.

  17. Optical Phased Array Using Guided Resonance with Backside Reflectors

    NASA Technical Reports Server (NTRS)

    Horie, Yu (Inventor); Arbabi, Amir (Inventor); Faraon, Andrei (Inventor)

    2016-01-01

    Methods and systems for controlling the phase of electromagnetic waves are disclosed. A device can consist of a guided resonance grating layer, a spacer, and a reflector. A plurality of devices, arranged in a grid pattern, can control the phase of reflected electromagnetic phase, through refractive index control. Carrier injection, temperature control, and optical beams can be applied to control the refractive index.

  18. The Proposed DESDynI Array-Fed Reflector Feed

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Hodges, R.; Vacchione, J.; Zawadzki, M.

    2012-01-01

    This paper describes the feed antenna for a proposed NASA Earth orbiting radar sensor currently in formulation at the Jet Propulsion Laboratory (JPL). The proposed array-fed reflector antenna architecture would enable large physical aperture imaging from space at relatively low cost and high technology readiness. Design, construction, and modeling of the feed antenna are described.

  19. Hollow optical waveguides with omni-directional reflectors

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Shou; Hou, Chia-Hung; Chien, Hung-Ta; Hsiao, Fu-Li; Chen, Chii-Chang

    2005-03-01

    In this study, we design and fabricate a hollow optical waveguide with omni-directional reflectors in silicon-based materials. A groove is etched by inductive coupled plasma (ICP) with photolithographic process on (100) silicon wafer. The width of the groove is varied from 3.5 to 5.5 micrometer for different waveguide designs. The depth of the groove is 1.2 micrometers. Plasma enhanced chemical vapor deposition is used to deposit six pairs of Si/SiO2(0.111/0.258micrometers) on the samples. Finally, the top of the sample is covered by another silicon substrate on which the identical omni-directional reflector has been also deposited. By wafer bonding technology, the top omni-directional reflector can be combined with the groove to form a hollow optical waveguide. Light with the wavelength at 1.55 micrometers can be confined by the omni-directional reflectors at single mode operation. Polarization independent hollow optical waveguides can be achieved with this fabrication process.

  20. Geometrically Nonlinear Finite Element Analysis of a Composite Space Reflector

    NASA Technical Reports Server (NTRS)

    Lee, Kee-Joo; Leet, Sung W.; Clark, Greg; Broduer, Steve (Technical Monitor)

    2001-01-01

    Lightweight aerospace structures, such as low areal density composite space reflectors, are highly flexible and may undergo large deflection under applied loading, especially during the launch phase. Accordingly, geometrically nonlinear analysis that takes into account the effect of finite rotation may be needed to determine the deformed shape for a clearance check and the stress and strain state to ensure structural integrity. In this study, deformation of the space reflector is determined under static conditions using a geometrically nonlinear solid shell finite element model. For the solid shell element formulation, the kinematics of deformation is described by six variables that are purely vector components. Because rotational angles are not used, this approach is free of the limitations of small angle increments. This also allows easy connections between substructures and large load increments with respect to the conventional shell formulation using rotational parameters. Geometrically nonlinear analyses were carried out for three cases of static point loads applied at selected points. A chart shows results for a case when the load is applied at the center point of the reflector dish. The computed results capture the nonlinear behavior of the composite reflector as the applied load increases. Also, they are in good agreement with the data obtained by experiments.

  1. Optical phased array using guided resonance with backside reflectors

    SciTech Connect

    Horie, Yu; Arbabi, Amir; Faraon, Andrei

    2016-11-01

    Methods and systems for controlling the phase of electromagnetic waves are disclosed. A device can consist of a guided resonance grating layer, a spacer, and a reflector. A plurality of devices, arranged in a grid pattern, can control the phase of reflected electromagnetic phase, through refractive index control. Carrier injection, temperature control, and optical beams can be applied to control the refractive index.

  2. Project Echo: Horn-Reflector Antenna for Space Communication

    NASA Technical Reports Server (NTRS)

    Crawford, A. B.; Hogg, D. C.; Hunt, L. E.

    1961-01-01

    This paper describes the mechanical features of the horn- reflector antenna used for receiving signals reflected from the Project Echo balloon satellite, and presents in some detail the electrical characteristics (radiation patterns and gain) measured at a frequency of 2390 Mc. Theoretically derived characteristics which agree very well with the measurements are also presented; details of the calculations are given in the appendices.

  3. 49 CFR 393.22 - Combination of lighting devices and reflectors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Combination of lighting devices and reflectors... Wiring § 393.22 Combination of lighting devices and reflectors. (a) Permitted combinations. Except as provided in paragraph (b) of this section, two or more lighting devices and reflectors (whether or...

  4. 49 CFR 393.22 - Combination of lighting devices and reflectors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Combination of lighting devices and reflectors... Wiring § 393.22 Combination of lighting devices and reflectors. (a) Permitted combinations. Except as provided in paragraph (b) of this section, two or more lighting devices and reflectors (whether or...

  5. 49 CFR 393.22 - Combination of lighting devices and reflectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Combination of lighting devices and reflectors... Wiring § 393.22 Combination of lighting devices and reflectors. (a) Permitted combinations. Except as provided in paragraph (b) of this section, two or more lighting devices and reflectors (whether or...

  6. 49 CFR 393.22 - Combination of lighting devices and reflectors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Combination of lighting devices and reflectors... Wiring § 393.22 Combination of lighting devices and reflectors. (a) Permitted combinations. Except as provided in paragraph (b) of this section, two or more lighting devices and reflectors (whether or...

  7. 49 CFR 393.22 - Combination of lighting devices and reflectors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Combination of lighting devices and reflectors... Wiring § 393.22 Combination of lighting devices and reflectors. (a) Permitted combinations. Except as provided in paragraph (b) of this section, two or more lighting devices and reflectors (whether or...

  8. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December 1...-towaway operation, must be equipped with retroreflective sheeting or an array of reflex reflectors...

  9. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December 1...-towaway operation, must be equipped with retroreflective sheeting or an array of reflex reflectors...

  10. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December 1...-towaway operation, must be equipped with retroreflective sheeting or an array of reflex reflectors...

  11. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December 1...-towaway operation, must be equipped with retroreflective sheeting or an array of reflex reflectors...

  12. 49 CFR 393.13 - Retroreflective sheeting and reflex reflectors, requirements for semitrailers and trailers...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Retroreflective sheeting and reflex reflectors... sheeting and reflex reflectors, requirements for semitrailers and trailers manufactured before December 1...-towaway operation, must be equipped with retroreflective sheeting or an array of reflex reflectors...

  13. Photosynthetic Carbon Reduction and Carbon Oxidation Cycles are the Main Electron Sinks for Photosystem II Activity During a Mild Drought

    PubMed Central

    CORNIC, GABRIEL; FRESNEAU, CHANTAL

    2002-01-01

    Stomatal closure can explain the inhibition of net CO2 uptake by a leaf subjected to a mild drought: the photosynthetic apparatus appears resistant to lack of water. Changes in both the water content of leaves maintained in a constant environment and the ambient CO2 molar fraction during measurements on well‐hydrated leaves lead to similar effects on net CO2 uptake and whole chain electron transport as estimated by leaf chlorophyll fluorescence measurements. In particular, it is shown that photosystem II (PSII) functioning and its regulation are not qualitatively changed during desiccation and that the variations in PSII photochemistry can simply be understood by changes in substrate availability in this condition. Moreover, an analysis of the literature shows that when inhibition of net CO2 uptake by C3 leaves under drought (Phaseolus vulgaris L., Helianthus annus L. and Solanum tuberosum L.) was lower than 80 %, elevated CO2 completely restored the photosynthetic capacity. The CO2 molar fraction in the chloroplasts declines as stomata close in drying leaves. As a consequence, in C3 plants, ribulose‐1,5‐bisphosphate oxygenation increases and becomes the main sink for photosynthetic electrons. Depending on the prevailing photon flux density, the O2 uptake through photorespiratory activity can entirely replace carbon dioxide as an electron acceptor, or not. The rate of the Mehler reaction remains low and unchanged during desiccation. However, drought could also involve CO2‐sensitive modification of the photosynthetic metabolism depending on plant growth conditions and possibly also on plant species. PMID:12102514

  14. Lamp system with conditioned water coolant and diffuse reflector of polytetrafluorethylene(PTFE)

    DOEpatents

    Zapata, Luis E.; Hackel, Lloyd

    1999-01-01

    A lamp system with a very soft high-intensity output is provided over a large area by water cooling a long-arc lamp inside a diffuse reflector of polytetrafluorethylene (PTFE) and titanium dioxide (TiO.sub.2) white pigment. The water is kept clean and pure by a one micron particulate filter and an activated charcoal/ultraviolet irradiation system that circulates and de-ionizes and biologically sterilizes the coolant water at all times, even when the long-arc lamp is off.

  15. The DESDynI Synthetic Aperture Radar Array-Fed Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Ghaemi, Hirad; Giersch, Louis; Harcke, Leif; Hodges, Richard; Hoffman, James; Johnson, William; Jordan, Rolando; Khayatian, Behrouz; Rosen, Paul; Sadowy, Gregory; Shaffer, Scott; Shen, Yuhsyen; Veilleux, Louise; Wu, Patrick

    2010-01-01

    DESDynI is a mission being developed by NASA with radar and lidar instruments for Earth-orbit remote sensing. This paper focuses on the design of a largeaperture antenna for the radar instrument. The antenna comprises a deployable reflector antenna and an active switched array of patch elements fed by transmit/ receive modules. The antenna and radar architecture facilitates a new mode of synthetic aperture radar imaging called 'SweepSAR'. A system-level description of the antenna is provided, along with predictions of antenna performance.

  16. Local thickening of the Cascadia forearc crust and the origin of seismic reflectors in the uppermost mantle

    USGS Publications Warehouse

    Calvert, A.J.; Ramachandran, K.; Kao, H.; Fisher, M.A.

    2006-01-01

    Seismic reflection profiles from three different surveys of the Cascadia forearc are interpreted using P wave velocities and relocated hypocentres, which were both derived from the first arrival travel time inversion of wide-angle seismic data and local earthquakes. The subduction decollement, which is characterized beneath the continental shelf by a reflection of 0.5 s duration, can be traced landward into a large duplex structure in the lower forearc crust near southern Vancouver Island. Beneath Vancouver Island, the roof thrust of the duplex is revealed by a 5–12 km thick zone, identified previously as the E reflectors, and the floor thrust is defined by a short duration reflection from a − 1. We suggest that these relatively low velocities indicate the presence of either crustal rocks from the oceanic plate that have been underplated to the continent or crustal rocks from the forearc that have been transported downward by subduction erosion. The absence of seismicity from within the E reflectors implies that they are significantly weaker than the overlying crust, and the reflectors may be a zone of active ductile shear. In contrast, seismicity in parts of the D reflectors can be interpreted to mean that ductile shearing no longer occurs in the landward part of the duplex. Merging of the D and E reflectors at 42–46 km depth creates reflectivity in the uppermost mantle with a vertical thickness of at least 15 km. We suggest that pervasive reflectivity in the upper mantle elsewhere beneath Puget Sound and the Strait of Georgia arises from similar shear zones.

  17. Stochastic and sensitivity analysis of shape error of inflatable antenna reflectors

    NASA Astrophysics Data System (ADS)

    San, Bingbing; Yang, Qingshan; Yin, Liwei

    2017-03-01

    Inflatable antennas are promising candidates to realize future satellite communications and space observations since they are lightweight, low-cost and small-packaged-volume. However, due to their high flexibility, inflatable reflectors are difficult to manufacture accurately, which may result in undesirable shape errors, and thus affect their performance negatively. In this paper, the stochastic characteristics of shape errors induced during manufacturing process are investigated using Latin hypercube sampling coupled with manufacture simulations. Four main random error sources are involved, including errors in membrane thickness, errors in elastic modulus of membrane, boundary deviations and pressure variations. Using regression and correlation analysis, a global sensitivity study is conducted to rank the importance of these error sources. This global sensitivity analysis is novel in that it can take into account the random variation and the interaction between error sources. Analyses are parametrically carried out with various focal-length-to-diameter ratios (F/D) and aperture sizes (D) of reflectors to investigate their effects on significance ranking of error sources. The research reveals that RMS (Root Mean Square) of shape error is a random quantity with an exponent probability distribution and features great dispersion; with the increase of F/D and D, both mean value and standard deviation of shape errors are increased; in the proposed range, the significance ranking of error sources is independent of F/D and D; boundary deviation imposes the greatest effect with a much higher weight than the others; pressure variation ranks the second; error in thickness and elastic modulus of membrane ranks the last with very close sensitivities to pressure variation. Finally, suggestions are given for the control of the shape accuracy of reflectors and allowable values of error sources are proposed from the perspective of reliability.

  18. Main Report

    PubMed Central

    2006-01-01

    scientific literature. The criteria were distributed among three main categories for each condition: The availability and characteristics of the screening test;The availability and complexity of diagnostic services; andThe availability and efficacy of treatments related to the conditions. A survey process utilizing a data collection instrument was used to gather expert opinion on the conditions in the first tier of the assessment. The data collection format and survey provided the opportunity to quantify expert opinion and to obtain the views of a diverse set of interest groups (necessary due to the subjective nature of some of the criteria). Statistical analysis of data produced a score for each condition, which determined its ranking and initial placement in one of three categories (high scoring, moderately scoring, or low scoring/absence of a newborn screening test). In the second tier of these analyses, the evidence base related to each condition was assessed in depth (e.g., via systematic reviews of reference lists including MedLine, PubMed and others; books; Internet searches; professional guidelines; clinical evidence; and cost/economic evidence and modeling). The fact sheets reflecting these analyses were evaluated by at least two acknowledged experts for each condition. These experts assessed the data and the associated references related to each criterion and provided corrections where appropriate, assigned a value to the level of evidence and the quality of the studies that established the evidence base, and determined whether there were significant variances from the survey data. Survey results were subsequently realigned with the evidence obtained from the scientific literature during the second-tier analysis for all objective criteria, based on input from at least three acknowledged experts in each condition. The information from these two tiers of assessment was then considered with regard to the overriding principles and other technology or condition

  19. Method and Apparatus for Linewidth Reduction in Distributed Feedback or Distributed Bragg Reflector Semiconductor Lasers using Vertical Emission

    NASA Technical Reports Server (NTRS)

    Cook, Anthony L. (Inventor); Hendricks, Herbert D. (Inventor)

    1998-01-01

    The linewidth of a distributed feedback semiconductor laser or a distributed Bragg reflector laser having one or more second order gratings is reduced by using an external cavity to couple the vertical emission back into the laser. This method and device prevent disturbance of the main laser beam. provide unobstructed access to laser emission for the formation of the external cavity. and do not require a very narrow heat sink. Any distributed Bragg reflector semiconductor laser or distributed feedback semiconductor laser that can produce a vertical emission through the epitaxial material and through a window in the top metallization can be used. The external cavity can be formed with an optical fiber or with a lens and a mirror of grating.

  20. A Nonlinear Dynamic Model and Free Vibration Analysis of Deployable Mesh Reflectors

    NASA Technical Reports Server (NTRS)

    Shi, H.; Yang, B.; Thomson, M.; Fang, H.

    2011-01-01

    This paper presents a dynamic model of deployable mesh reflectors, in which geometric and material nonlinearities of such a space structure are fully described. Then, by linearization around an equilibrium configuration of the reflector structure, a linearized model is obtained. With this linearized model, the natural frequencies and mode shapes of a reflector can be computed. The nonlinear dynamic model of deployable mesh reflectors is verified by using commercial finite element software in numerical simulation. As shall be seen, the proposed nonlinear model is useful for shape (surface) control of deployable mesh reflectors under thermal loads.

  1. Concepts and analysis for precision segmented reflector and feed support structures

    NASA Technical Reports Server (NTRS)

    Miller, Richard K.; Thomson, Mark W.; Hedgepeth, John M.

    1990-01-01

    Several issues surrounding the design of a large (20-meter diameter) Precision Segmented Reflector are investigated. The concerns include development of a reflector support truss geometry that will permit deployment into the required doubly-curved shape without significant member strains. For deployable and erectable reflector support trusses, the reduction of structural redundancy was analyzed to achieve reduced weight and complexity for the designs. The stiffness and accuracy of such reduced member trusses, however, were found to be affected to a degree that is unexpected. The Precision Segmented Reflector designs were developed with performance requirements that represent the Reflector application. A novel deployable sunshade concept was developed, and a detailed parametric study of various feed support structural concepts was performed. The results of the detailed study reveal what may be the most desirable feed support structure geometry for Precision Segmented Reflector/Large Deployable Reflector applications.

  2. Detection of reflector surface error from near-field data: Effect of edge diffracted field

    NASA Technical Reports Server (NTRS)

    Cherrette, Alan R.; Lee, Shong W.; Acosta, Roberto J.

    1987-01-01

    The surface accuracy of large reflector antennas must be maintained within certain tolerances if high gain/low sidelobe performance is to be achieved. Thus the measurement of the surface profile is an important part of the quality control procedure when constructing antennas of this type. An efficient method for surface profile measurement has been proposed, i.e., the reflector surface is calculated from the measured near-field phase data using the theory of geometric optics. For a surface profile calculation of this kind, it is necessary to know the margin of error built into the method of calculation. This will enable a specification of the tolerance from which the surface profile can be determined. When calculating the surface profile from near-field phase data, there are two main sources of error. The first is the measurement error in near-field phase data. The second arises from the edge diffracted fields that are superimposed on the reflected fields in the measured near-field data. The error in the calculated surface profile produced by the edge diffracted fields is examined.

  3. Switchable reflector in the Panamanian tortoise beetle Charidotella egregia (Chrysomelidae: Cassidinae)

    NASA Astrophysics Data System (ADS)

    Vigneron, Jean Pol; Pasteels, Jacques M.; Windsor, Donald M.; Vértesy, Zofia; Rassart, Marie; Seldrum, Thomas; Dumont, Jacques; Deparis, Olivier; Lousse, Virginie; Biró, László P.; Ertz, Damien; Welch, Victoria

    2007-09-01

    The tortoise beetle Charidotella egregia is able to modify the structural color of its cuticle reversibly, when disturbed by stressful external events. After field observations, measurements of the optical properties in the two main stable color states and scanning electron microscope and transmission electron microscope investigations, a physical mechanism is proposed to explain the color switching of this insect. It is shown that the gold coloration displayed by animals at rest arises from a chirped multilayer reflector maintained in a perfect coherent state by the presence of humidity in the porous patches within each layer, while the red color displayed by disturbed animals results from the destruction of this reflector by the expulsion of the liquid from the porous patches, turning the multilayer into a translucent slab that leaves an unobstructed view of the deeper-lying, pigmented red substrate. This mechanism not only explains the change of hue but also the change of scattering mode from specular to diffuse. Quantitative modeling is developed in support of this analysis.

  4. High reflectivity III-nitride UV-C distributed Bragg reflectors for vertical cavity emitting lasers

    NASA Astrophysics Data System (ADS)

    Franke, A.; Hoffmann, M. P.; Kirste, R.; Bobea, M.; Tweedie, J.; Kaess, F.; Gerhold, M.; Collazo, R.; Sitar, Z.

    2016-10-01

    UV-C distributed Bragg reflectors (DBRs) for vertical cavity surface emitting laser applications and polariton lasers are presented. The structural integrity of up to 25 layer pairs of AlN/Al0.65Ga0.35N DBRs is maintained by balancing the tensile and compressive strain present between the single layers of the multilayer stack grown on top of an Al0.85Ga0.35N template. By comparing the structural and optical properties for DBRs grown on low dislocation density AlN and AlGaN templates, the criteria for plastic relaxation by cracking thick nitride Bragg reflectors are deduced. The critical thickness is found to be limited mainly by the accumulated strain energy during the DBR growth and is only negligibly affected by the dislocations. A reflectance of 97.7% at 273 nm is demonstrated. The demonstrated optical quality and an ability to tune the resonance wavelength of our resonators and microcavity structures open new opportunities for UV-C vertical emitters.

  5. Shape adjustment of cable mesh reflector antennas considering modeling uncertainties

    NASA Astrophysics Data System (ADS)

    Du, Jingli; Bao, Hong; Cui, Chuanzhen

    2014-04-01

    Cable mesh antennas are the most important implement to construct large space antennas nowadays. Reflector surface of cable mesh antennas has to be carefully adjusted to achieve required accuracy, which is an effective way to compensate manufacturing and assembly errors or other imperfections. In this paper shape adjustment of cable mesh antennas is addressed. The required displacement of the reflector surface is determined with respect to a modified paraboloid whose axial vertex offset is also considered as a variable. Then the adjustment problem is solved by minimizing the RMS error with respect to the desired paraboloid using minimal norm least squares method. To deal with the modeling uncertainties, the adjustment is achieved by solving a simple worst-case optimization problem instead of directly using the least squares method. A numerical example demonstrates the worst-case method is of good convergence and accuracy, and is robust to perturbations.

  6. High contrast reflective liquid crystal display using a thermochromic reflector

    NASA Astrophysics Data System (ADS)

    Heo, Kyong Chan; Yi, Jonghoon; Kwon, Jin Hyuk; Seog Gwag, Jin

    2015-02-01

    This paper presents a reflective liquid crystal display (LCD) with a high contrast ratio (CR) combined with mono-type thermochromic materials to solve the low CR of reflective type LCDs. Here, reflective, wide-band, electrically controlled birefringence mode was used as the optical liquid crystal (LC) mode, and a thermochromic material was used as the reflector for the white state and an absorber for the dark state. The combination of LCD and thermochromic material can have a synergistic effect in achieving a better display. By controlling the reflectance of the thermochromic reflector using Joule heating, the proposed reflective LC cell exhibited a high CR of approximately 70:1. The figure was extremely high compared to the approximately 10:1 of a typical reflective LC cell with an optically wide band design. The proposed LC cell configuration is expected to find many outdoor applications which can admit slow response speed.

  7. Cavity optomechanics with 2D photonic crystal membrane reflectors

    NASA Astrophysics Data System (ADS)

    Lingaraju, Navin B.; Shuai, Yichen; Lawall, John

    2016-03-01

    Membranes made from silicon nitride have significantly higher mechanical Q-factors under tensile stress than those made of other dielectric materials. This makes them ideal candidates for membrane reflectors that provide high finesse in Fabry-Perot cavities or membrane-in-the-middle optomechanical systems. Building on our previous work with one-dimensional gratings on suspended membranes, we patterned two-dimensional photonic crystal gratings on monolithic, suspended membranes made from silicon nitride. These high-Q membranes exhibited high reflectivity, upwards of 99%, over several nanometers in the telecom band. To probe their optical response in a cavity environment, we used these membrane reflectors as the moving mirror in a Fabry-Perot cavity. We were able to realize cavities with a finesse of over 4,500.

  8. Gratings and Random Reflectors for Near-Infrared PIN Diodes

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath; Bandara, Sumith; Liu, John; Ting, David

    2007-01-01

    Crossed diffraction gratings and random reflectors have been proposed as means to increase the quantum efficiencies of InGaAs/InP positive/intrinsic/ negative (PIN) diodes designed to operate as near-infrared photodetectors. The proposal is meant especially to apply to focal-plane imaging arrays of such photodetectors to be used for near-infrared imaging. A further increase in quantum efficiency near the short-wavelength limit of the near-infrared spectrum of such a photodetector array could be effected by removing the InP substrate of the array. The use of crossed diffraction gratings and random reflectors as optical devices for increasing the quantum efficiencies of quantum-well infrared photodetectors (QWIPs) was discussed in several prior NASA Tech Briefs articles. While the optical effects of crossed gratings and random reflectors as applied to PIN photodiodes would be similar to those of crossed gratings and random reflectors as applied to QWIPs, the physical mechanisms by which these optical effects would enhance efficiency differ between the PIN-photodiode and QWIP cases: In a QWIP, the multiple-quantum-well layers are typically oriented parallel to the focal plane and therefore perpendicular or nearly perpendicular to the direction of incidence of infrared light. By virtue of the applicable quantum selection rules, light polarized parallel to the focal plane (as normally incident light is) cannot excite charge carriers and, hence, cannot be detected. A pair of crossed gratings or a random reflector scatters normally or nearly normally incident light so that a significant portion of it attains a component of polarization normal to the focal plane and, hence, can excite charge carriers. A pair of crossed gratings or a random reflector on a PIN photodiode would also scatter light into directions away from the perpendicular to the focal plane. However, in this case, the reason for redirecting light away from the perpendicular is to increase the length of the

  9. The design of the Central-Axis Reflector (ZAS)

    NASA Astrophysics Data System (ADS)

    Huegenell, Hermann

    1989-10-01

    This paper discusses the design principles of the Central-Axis Reflector (ZAS), a segmented-mirror telescope designed to produce large light-gathering areas, with particular attention given to the optical system and the tracking apparatus of the ZAS. The paper also describes the manufacturing method for the primary mirror of the ZAS, the structure of the mirror bodies, the grinding and polishing method, and the structures and procedures used for mounting and adjustment of the individual mirror bodies. Consideration is also given to sensors and control systems, the optical path of the incident light, and a protecting dome. A variant of the ZAS, the Central-Axis Inclined Reflector, is also described.

  10. Reflectors for canning a BaF 2 crystal

    NASA Astrophysics Data System (ADS)

    Sinha, B. K.; Bhattacharya, R.

    1989-03-01

    The performance of BaF 2 crystals with various reflectors like teflon tape, ZrO 2, Al 2O 3 and CaF 2 powders is tested by measuring the energy and time resolution at different energies. It is shown that CaF 2 powder is a somewhat better reflector than the Al 2O 3 powder so far used by different workers. It is also seen that the reflectivity of CaF 2 powder for the BaF 2 emission spectrum is not much inferior to that of teflon tape which is, however, the best reported so far. Based on these observations a method of canning a BaF 2 crystal is proposed.

  11. Semiconductor hollow optical waveguides formed by omni-directional reflectors

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Shou; Wang, Mou-Sian; Chen, Chii-Chang

    2004-12-01

    In this study, a hollow optical waveguide with omni-directional reflectors in silicon-based materials was design, fabricated and characterized. By using dry etching technique, plasma-enhanced chemical vapor deposition for Si/SiO2 thin films and covering another wafer with omni-directional reflector together, the waveguides can be formed with an air core of 1.2μm x 1.3μm. A uniform propagation loss of the waveguide to be around 1.7dB/cm for C+L band was found for the TE and TM modes. Polarization-independent hollow optical waveguides were obtained with the hollow waveguide structure.

  12. Grating-assisted silicon-on-insulator racetrack resonator reflector.

    PubMed

    Boeck, Robert; Caverley, Michael; Chrostowski, Lukas; Jaeger, Nicolas A F

    2015-10-05

    We experimentally demonstrate a grating-assisted silicon-on-insulator (SOI) racetrack resonator reflector with a reflect port suppression of 10.3 dB and no free spectral range. We use contra-directional grating couplers within the coupling regions of the racetrack resonator to enable suppression of all but one of the peaks within the reflect port spectrum as well as all but one of the notches within the through port spectrum.

  13. Simplified Velocity Interferometer System for Any Reflector (VISAR) system

    SciTech Connect

    Sweatt, W.C.; Stanton, P.L.; Crump, O.B. Jr.

    1990-01-01

    A simplified, rugged VISAR (Velocity Interferometer System for Any Reflector) system has been developed using a non-removable delay element and an essentially non-adjustable interferometer cavity. In this system, the critical interference adjustments are performed during fabrication of the cavity, freeing the user from this task. Prototype systems are easy to use and give extremely high quality results. 6 refs., 7 figs.

  14. Aquarius Reflector Surface Temperature Monitoring Test and Analysis

    NASA Technical Reports Server (NTRS)

    Abbott, Jamie; Lee, Siu-Chun; Becker, Ray

    2008-01-01

    The presentation addresses how to infer the front side temperatures for the Aquarius L-band reflector based upon backside measurement sites. Slides discussing the mission objectives and design details are at the same level found on typical project outreach websites and in conference papers respectively. The test discussion provides modest detail of an ordinary thermal balance test using mockup hardware. The photographs show an off-Lab vacuum chamber facility with no compromising details.

  15. Cube-corner reflectors with interference dielectric coating

    SciTech Connect

    Sokolov, A L; Murashkin, V V; Akent'ev, A S; Karaseva, E A

    2013-09-30

    The cube-corner reflectors (CCRs) with a special interference dielectric coating intended for ring retroreflector systems of space vehicles with uniaxial orientation are considered. The diffraction patterns of radiation reflected from the CCRs with different face coatings are studied. It is shown that the choice of the angle between the faces, the size and the coating of CCR faces allow essential variation in the diffraction pattern, thereby providing its optimisation for solving different navigation problems. (nanogradient dielectric coatings and metamaterials)

  16. Shape control of distributed parameter reflectors using sliding mode control

    NASA Astrophysics Data System (ADS)

    Andoh, Fukashi; Washington, Gregory N.; Utkin, Vadim

    2001-08-01

    Sliding mode control has become one of the most powerful control methods for variable structure systems, a set of continuous systems with an appropriate switching logic. Its robustness properties and order reduction capability have made sliding mode control one of the most efficient tools for relatively higher order nonlinear plants operating under uncertain conditions. Piezo-electric materials possess the property of creating a charge when subjected to a mechanical strain, and of generating a strain when subjected to an electric field. Piezo-electric actuators are known to have a hysteresis due to the thermal motion and Coulomb interaction of Weiss domains. Because of the thermal effect the hysteresis of piezo-electric actuators is reproducible only with some uncertainty in experiments. The robustness of sliding mode control under uncertain conditions has an advantage in handling the hysteresis of piezo-electric actuators. In this research sliding mode control is used to control the shape of one- and two-dimensionally curved adaptive reflectors with piezo-electric actuators. Four discrete linear actuators for the one-dimensionally curved reflector and eight actuators for the two-dimensionally curved reflector are assumed.

  17. Diffractive surfaces for cat-eye array retro-reflectors

    NASA Astrophysics Data System (ADS)

    Glaser, I.

    2008-09-01

    Cat-eye-array retro-reflectors, combining a lenslet array with a reflective surface at the common focal plane of the lenslets, are widely used due to their simple structure and low cost. While for many applications the performance (brightness, acceptance angle range and directionality) is acceptable, others could benefit from better performance. Improving these retroreflectors is difficult because their simplicity results in too few degrees of freedom. Here, we show how the use of one or two diffractive surfaces can significantly increase the brightness of the reflected beam and/or the acceptance angle while still allowing inexpensive manufacturing by molding or replication. Specifically, we focus here on one potential application of cat-eye-array retro-reflectors: semipassive optical communication units. Semi-passive communication units combine a retroreflector with a light modulator. The directional auto-aligned retro-reflected signal enhances security and power efficiency. Furthermore, many modulators use very low power: far lower than light emitter. Modulated retro-reflectors have already been demonstrated for space and military communication. Here we focus on a different application: optical smart cards. These devices described elsewhere, can be used, for example, for access control identification or as non-contact secure teller machine ID. Such devices must have an optical modulator in the optical path, so the effect of the modulator must also be accounted for in the design. As a consumer product, low cost manufacturability is another requirement. Design examples are presented.

  18. Modulating Retro-Reflectors: Technology, Link Budgets and Applications

    NASA Technical Reports Server (NTRS)

    Salas, Alberto Guillen; Stupl, Jan; Mason, James

    2012-01-01

    Satellite communications systems today -- usually radio frequency (RF) -- tend to have low data rates and use a lot of on-board power. For CubeSats, communications often dominate the power budget. We investigate the use of modulating retro-reflectors (MRRs), previously demonstrated on the ground, for high data-rate communication downlinks from small satellites. A laser ground station would illuminate a retro-reflector on-board the satellite while an element in the retro-reflector modulates the intensity of the reflected signal, thereby encoding a data stream on the returning beam. A detector on the ground receives the data, keeping the complex systems and the vast majority of power consumption on the ground. Reducing the power consumption while increasing data rates would relax constraints on power budgets for small satellites, leaving more power available for payloads. In the future, this could enable the use of constellations of nano-satellites for a variety of missions, possibly leading to a paradigm shift in small satellite applications.

  19. Shape control of slack space reflectors using modulated solar pressure.

    PubMed

    Borggräfe, Andreas; Heiligers, Jeannette; Ceriotti, Matteo; McInnes, Colin R

    2015-07-08

    The static deflection profile of a large spin-stabilized space reflector because of solar radiation pressure acting on its surface is investigated. Such a spacecraft consists of a thin reflective circular film, which is deployed from a supporting hoop structure in an untensioned, slack manner. This paper investigates the use of a variable reflectivity distribution across the surface to control the solar pressure force and hence the deflected shape. In this first analysis, the film material is modelled as one-dimensional slack radial strings with no resistance to bending or transverse shear, which enables a semi-analytic derivation of the nominal deflection profile. An inverse method is then used to find the reflectivity distribution that generates a specific, for example, parabolic deflection shape of the strings. Applying these results to a parabolic reflector, short focal distances can be obtained when large slack lengths of the film are employed. The development of such optically controlled reflector films enables future key mission applications such as solar power collection, radio-frequency antennae and optical telescopes.

  20. Silicon solar cell using optimized intermediate reflector layer

    NASA Astrophysics Data System (ADS)

    Khalifa, Ahmed E.; Swillam, Mohamed A.

    2016-03-01

    Thin film silicon based photovoltaic cells have the advantages of using low cost nontoxic abundant constituents and low thermal manufacturing budget. However, better long-term efficiencies need to be achieved overcoming its inherent bad electrical properties of amorphous and/or microcrystalline Silicon. For the goal of achieving best results, multijunction cells of amorphous and microcrystalline silicon thin layers are industrially and lab utilized in addition to using one or more light management techniques such as textured layers, periodic and plasmonic back reflectors, flattened reflective substrates and intermediate reflector layer (IRL) between multijunction cells. The latter, IRL, which is the focus of this paper, serves as spectrally selective layer between different cells of the multijunction silicon thin film solar cell. IRL, reflects to the top cell short wavelength while permitting and scattering longer ones to achieve the best possible short circuit current. In this study, a new optimized periodic design of Intermediate reflector layer in micromorph (two multijunction cells of Microcrystalline and Amorphous Silicon) thin film solar cells is proposed. The optically simulated short circuit current reaches record values for same thickness designs when using all-ZnO design and even better results is anticipated if Lacquer material is used in combination with ZnO. The design methodology used in the paper can be easily applied to different types of IRL materials and also extended to triple and the relatively newly proposed quadruple thin films solar cells.

  1. Shape control of slack space reflectors using modulated solar pressure

    PubMed Central

    Borggräfe, Andreas; Heiligers, Jeannette; Ceriotti, Matteo; McInnes, Colin R.

    2015-01-01

    The static deflection profile of a large spin-stabilized space reflector because of solar radiation pressure acting on its surface is investigated. Such a spacecraft consists of a thin reflective circular film, which is deployed from a supporting hoop structure in an untensioned, slack manner. This paper investigates the use of a variable reflectivity distribution across the surface to control the solar pressure force and hence the deflected shape. In this first analysis, the film material is modelled as one-dimensional slack radial strings with no resistance to bending or transverse shear, which enables a semi-analytic derivation of the nominal deflection profile. An inverse method is then used to find the reflectivity distribution that generates a specific, for example, parabolic deflection shape of the strings. Applying these results to a parabolic reflector, short focal distances can be obtained when large slack lengths of the film are employed. The development of such optically controlled reflector films enables future key mission applications such as solar power collection, radio-frequency antennae and optical telescopes. PMID:26345083

  2. Tunable hollow waveguide distributed Bragg reflectors with variable air core

    NASA Astrophysics Data System (ADS)

    Sakurai, Yasuki; Koyama, Fumio

    2004-06-01

    We demonstrate a tunable hollow waveguide distributed Bragg reflector consisting of a grating loaded slab hollow waveguide with a variable air-core. The modeling shows that a change in an air-core thickness enables a large shift of several tens of nanometers in Bragg wavelength due to a change of several percents in a propagation constant. We fabricated a slab hollow waveguide Bragg reflector with 620 μm long and, 190 nm deep 1st-order circular grating composed of SiO2, exhibiting strong Bragg reflection at 1558 nm with an air-core thickness of 10 μm for TM mode. The peak reflectivity is 65% including fiber coupling losses, the 3-dB bandwidth is 2.8 nm and the grating-induced loss is less than 0.5 dB. We demonstrate a 3 nm wavelength tuning of the fabricated hollow waveguide Bragg reflector by changing an air-core thickness from 10 μm to 7.9 μm.

  3. Terrace retro-reflector array for poloidal polarimeter on ITER.

    PubMed

    Imazawa, R; Kawano, Y; Ono, T; Kusama, Y

    2011-02-01

    A new concept of a terrace retro-reflector array (TERRA) as part of the poloidal polarimeter for ITER is proposed in this paper. TERRA reflects a laser light even from a high incident angle in the direction of the incident-light path, while a conventional retro-reflector array cannot. Besides, TERRA can be installed in a smaller space than a corner-cube retro-reflector. In an optical sense, TERRA is equivalent to a Littrow grating, the blaze angle of which varies, depending on the incident angle. The reflected light generates a bright and dark fringe, and the bright fringe is required to travel along the incident-light path to achieve the objects of laser-aided diagnostics. In order to investigate the propagation properties of laser light reflected by TERRA, we have developed a new diffraction formula. Conditions for the propagation of the bright fringe in the direction of the incident light have been obtained using the Littrow grating model and have been confirmed in a simulation applying the new diffraction formula. Finally, we have designed laser transmission optics using TERRA for the ITER poloidal polarimeter and have calculated the light propagation of the system. The optical design obtains a high transmission efficiency, with 88.6% of the incident power returned. These results demonstrate the feasibility of applying TERRA to the ITER poloidal polarimeter.

  4. Accurate data fitting for adjustments of focus position coordinates applied to cassegrain antenna's sub-reflector compensation

    NASA Astrophysics Data System (ADS)

    Hu, Kaiyu; Aili, Yusup; Xu, Xuelin; Xiang, Binbin; Liu, Qi

    2014-12-01

    Based on the rapidly progress of the Xinjiang 110 m radio telescope project, Nanshan antenna reform programme and national strategic demand for aerospace development, this paper makes a thorough study for the real-time compensation of the sub-reflector for the deformation of the large antenna's main panel. First, it presents a brief introduction to the theoretical model of sub-reflector compensation and an analysis of adjustments under certain special elevations. Then it realizes high-precision data fit using MATLAB because of its powerful numerical calculation. This paper gives two different data fit methods and model equations and compares the effects of the two fit methods from different aspects by detailed error analysis. When the fit order is 4 and computing to 15 decimal places, it calculates the error of the difference between these two data fit methods: the value is negative and the magnitude is 10-13 mm. Finally, the paper chooses the higher precision fitting method whose absolute error is minuend and uses this method to generate a partial adjustment database in the range of some special angels in order to create conditions for the entire sub-reflector compensation process which satisfies the requirements for astronomical observations and deep-space exploration for data accuracy and system reliability. The specific technology is believed to possess certain general value for applicability.

  5. High-output LED-based light engine for profile lighting fixtures with high color uniformity using freeform reflectors.

    PubMed

    Gadegaard, Jesper; Jensen, Thøger Kari; Jørgensen, Dennis Thykjær; Kristensen, Peter Kjær; Søndergaard, Thomas; Pedersen, Thomas Garm; Pedersen, Kjeld

    2016-02-20

    In the stage lighting and entertainment market, light engines (LEs) for lighting fixtures are often based on high-intensity discharge (HID) bulbs. Switching to LED-based light engines gives possibilities for fast switching, additive color mixing, a longer lifetime, and potentially, more energy-efficient systems. The lumen output of a single LED is still not sufficient to replace an HID source in high-output profile fixtures, but combining multiple LEDs can create an LE with a similar output, but with added complexity. This paper presents the results of modeling and testing such a light engine. Custom ray-tracing software was used to design a high-output red, green and blue LED-based light engine with twelve CBT-90 LEDs using a dual-reflector principle. The simulated optical system efficiency was 0.626 with a perfect (R=1) reflector coating for light delivered on a target surface through the entire optical system. A profile lighting fixture prototype was created, and provided an output of 6744 lumen and an efficiency of 0.412. The lower efficiency was mainly due to a non-optimal reflector coating, and the optimized design is expected to reach a significantly higher efficiency.

  6. A new fabrication method for precision antenna reflectors for space flight and ground test

    NASA Technical Reports Server (NTRS)

    Sharp, G. Richard; Wanhainen, Joyce S.; Ketelsen, Dean A.

    1991-01-01

    Communications satellites are using increasingly higher frequencies that require increasingly precise antenna reflectors for use in space. Traditional industry fabrication methods for space antenna reflectors employ successive modeling techniques using high- and low-temperature molds for reflector face sheets and then a final fit-up of the completed honeycomb sandwich panel antenna reflector to a master pattern. However, as new missions are planned at much higher frequencies, greater accuracies will be necessary than are achievable using these present methods. A new approach for the fabrication of ground-test solid-surface antenna reflectors is to build a rigid support structure with an easy-to-machine surface. This surface is subsequently machined to the desired reflector contour and coated with a radio-frequency-reflective surface. This method was used to fabricate a 2.7-m-diameter ground-test antenna reflector to an accuracy of better than 0.013 mm (0.0005 in.) rms. A similar reflector for use on spacecraft would be constructed in a similar manner but with space-qualified materials. The design, analysis, and fabrication of the 2.7-m-diameter precision antenna reflector for antenna ground tests and the extension of this technology to precision, space-based antenna reflectors are described.

  7. Design and optimization of ultrathin crystalline silicon solar cells using an efficient back reflector

    NASA Astrophysics Data System (ADS)

    Saravanan, S.; Dubey, R. S.; Kalainathan, S.; More, M. A.; Gautam, D. K.

    2015-05-01

    Thin film solar cells are cheaper but having low absorption in longer wavelength and hence, an effective light trapping mechanism is essential. In this work, we proposed an ultrathin crystalline silicon solar cell which showed extraordinary performance due to enhanced light absorption in visible and infrared part of solar spectrum. Various designing parameters such as number of distributed Bragg reflector (DBR) pairs, anti-reflection layer thickness, grating thickness, active layer thickness, grating duty cycle and period were optimized for the optimal performance of solar cell. An ultrathin silicon solar cell with 40 nm active layer could produce an enhancement in cell efficiency ˜15 % and current density ˜23 mA/cm2. This design approach would be useful for the realization of new generation of solar cells with reduced active layer thickness.

  8. Final Technical Report for grant entitled "New Horizons in C-F Activation by Main Group Electrophiles"

    SciTech Connect

    Ozerov, Oleg V; Ozerov, Oleg V.

    2014-01-16

    We became interested in developing new methods for hydrodefluorination (HDF) and other types of C-F bond conversion in polyfluoroalkanes under mild conditions. We were attracted to an approach to C-F activation, where the key C-F cleavage proceeds by a Lewis acid abstraction of fluoride rather than a redox event. The efforts during the previous period were aimed at a) advancing the HDF reactivity with improvement in scope and catalyst longevity; b) extending C-F activation beyond HDF; c) generating insight about the elementary steps of the reaction and potential intermediates.

  9. Switchable broadband terahertz absorber/reflector enabled by hybrid graphene-gold metasurface.

    PubMed

    Zhao, Yu Tong; Wu, Bian; Huang, Bei Ju; Cheng, Qiang

    2017-04-03

    Numerous studies have been made to design switchable terahertz absorber for the application of amplitude modulator. However, it is still a challenge to achieve large modulation range while maintaining broad bandwidth. Here, we propose a switchable broadband absorber/reflector in the low-terahertz regime. By utilizing a hybrid graphene-gold metasurface on SiO2/pSi/PDMS substrate with an aluminum back, an excellent absorption across 0.53-1.05 THz with a wide incident angles for both TE and TM polarizations is achieved. By controlling the voltage across gold electrode and pSi, the chemical potential of graphene can be changed correspondingly. When the chemical potential of graphene varied from 0eV to 0.3eV, the state of the proposed structure can be switched from absorption (>90%) to reflection (>82%) over the whole operation bandwidth. Electric field intensity and surface loss density of the proposed absorber under different chemical potential are given to have a physical insight of the mechanisms. The switchable absorber/reflector can enable a wide application of high performance terahertz devices, such as active camouflage, imaging, modulators and electro-optic switches.

  10. The large deployable reflector: A NASA submillimeter-infrared orbiting observatory

    NASA Technical Reports Server (NTRS)

    Swanson, Paul N.

    1986-01-01

    The Large Deployable Reflector (LDR) concept is outlined. The LDR telescope is based on a 20-m diameter reflector. The primary mirror is a filled aperture made up of 84 hexagonal panels, each 2 m edge-to-edge. The panels are based on lightweight structural composite materials. The optical configuration is a four mirror two stage system. The primary mirror is passive. The active optical elements for figure control are at the quaternary mirror. The primary mirror panels are supported by a deployable PAC truss backup structure at the vertices of each hexagon. The four focal plane instruments covering the range of 30 to 1000 microns are located near the vertex of the primary mirror. Some instruments will be cooled with stored cryogens to liquid helium temperatures, others to liquid nitrogen temperatures. The spacecraft functions will be located in a resource module behind the primary mirror. The LDR will be transferred to orbit by the space transportation system and assembled and tested at the space station. It will then be boosted to an orbit of greater than or = 700 km as a free flyer.

  11. Enhanced performance of semitransparent inverted organic photovoltaic devices via a high reflector structure.

    PubMed

    Zhang, Dan-Dan; Jiang, Xiao-Chen; Wang, Rong; Xie, Hao-Jun; Ma, Guo-Fu; Ou, Qing-Dong; Chen, Yuan-Li; Li, Yan-Qing; Tang, Jian-Xin

    2013-10-23

    Significantly enhanced performances of semitransparent inverted organic photovoltaic devices have been realized by simply introducing a high reflector structure, which comprises several pairs of MoO3/LiF with a thickness of 60 nm for MoO3 and 90 nm for LiF, respectively. After optimizing the reflector structure, the enhanced light harvesting is achieved, and thus the increased optical current is obtained. The short-circuit current density (JSC) and power conversion efficiency (PCE) are increased to 10.9 mA cm(-2) and 4.32%, compared to 8.09 mA cm(-2) and 3.36% in the control device. This leads to a 30% enhancement in PCE. According to the experimental and simulated results, the improved performance is attributed to the effective reflection of light at the wavelength from 450 to 600 nm, which corresponds to the absorption range of the active layer. The demonstrated light-trapping approach is expected to be an effective method to realize the high efficiency in semitransparent organic photovoltaic devices.

  12. Concept Design of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Spence, Thomas; Cooley, Michael E.; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

    2016-01-01

    A scalable dual-band (Ka/W) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of the planned NASA Earth Science Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflectarray with a fixed pointing W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflectarray surface. More recently the science community has expressed interest in a mission that offers the ability to measure precipitation in addition to clouds and aerosols. In this paper we present summaries of multiple designs that explore options for realizing a tri-frequency (Ku/Ka/W), shared-aperture antenna system to meet these science objectives. Design considerations include meeting performance requirements while emphasizing payload size, weight, prime power, and cost. The extensive trades and lessons learned from our previous dual-band ACE system development were utilized as the foundation for this work.

  13. Development of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna Design for NASA

    NASA Technical Reports Server (NTRS)

    Spence, Thomas; Cooley, Michael; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

    2016-01-01

    A dual-band (Ka/W) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of NASA's planned Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflect array with a fixed W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflect array surface. More recently the science community has expressed interest in a mission that offers the ability to measure precipitation (Ku- band with scanning) in addition to clouds and aerosols. In this paper we present findings from a design study that explores options for realizing a tri-frequency (Ku/Ka/W), shared-aperture antenna system to meet these science objectives. Design considerations included meeting performance requirements while striving to minimize payload size, weight, prime power, and cost. The extensive trades and lessons learned from the ACE system development were utilized as the foundation for this work.

  14. Concept Design of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Spence, Thomas; Cooley, Michael; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

    2016-01-01

    A scalable dual-band (KaW) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of the planned NASA Earth Science Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflectarray with a fixed pointing W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflectarray surface.More recently the science community has expressed interest in a mission that offers the ability to measure precipitation in addition to clouds and aerosols. In this paper we present summaries of multiple designs that explore options for realizing a tri-frequency (KuKaW), shared-aperture antenna system to meet these science objectives. Design considerations include meeting performance requirements while emphasizing payload size, weight, prime power, and cost. The extensive trades and lessons learned from our previous dual-band ACE system development were utilized as the foundation for this work.

  15. Vertical cavity surface emitting laser emitting at 1.56 microns with AlGaAsSb/AlAsSb distributed Bragg reflectors

    SciTech Connect

    Blum, O.; Klem, J.F.; Lear, K.L.; Vawter, G.A.; Kurtz, S.R.

    1998-07-01

    The authors report 77K operation of an optically pumped vertical cavity surface emitting laser with an Sb-based cavity. The structure consists of 15 and 20 pair AlGaAsSb/AlAsSb top and bottom reflectors and a bulk InGaAs active region.

  16. Flight activity of USDA-ARS Russian honey bees (Hymenoptera: Apidae) during pollination of lowbush blueberries in Maine.

    PubMed

    Danka, Robert G; Beaman, Lorraine D

    2007-04-01

    Flight activity was compared in colonies of Russian honey bees, Apis mellifera L. (Hymenoptera: Apidae), and Italian bees during commercial pollination of lowbush blueberries (principally Vaccinium angustifolium Aiton) in Washington Co., ME, in late May and early June in 2003 and 2004. Colonies of the two stocks were managed equally in Louisiana during autumn through early spring preceding observations in late spring each year. Resulting average populations of adult bees and of brood were similar in colonies of the two bee stocks during pollination. Flight during pollination was monitored hourly on 6 d each year by counting bees exiting each colony per minute; counts were made manually with flight cones on 17 colonies per stock in 2003 and electronically with ApiSCAN-Plus counters on 20 colonies per stock in 2004. Analysis of variance showed that temperature, colony size (population of adult bees or brood), and the interaction of these effects were the strongest regulators of flight activity in both years. Russian and Italian bees had similar flight activity at any given colony size, temperature, or time of day. Flight increased linearly with rising temperatures and larger colony sizes. Larger colonies, however, were more responsive than smaller colonies across the range of temperatures measured. In 2003, flight responses to varying temperatures were less in the afternoon and evening (1500-1959 hours) than they were earlier in the day. Russian colonies had flight activity that was suitable for late spring pollination of lowbush blueberries.

  17. 25 years of N-heterocyclic carbenes: activation of both main-group element-element bonds and NHCs themselves.

    PubMed

    Würtemberger-Pietsch, Sabrina; Radius, Udo; Marder, Todd B

    2016-04-14

    N-Heterocyclic carbenes (NHCs) are widely used ligands and reagents in modern inorganic synthesis as well as in homogeneous catalysis and organocatalysis. However, NHCs are not always innocent bystanders. In the last few years, more and more examples were reported of reactions of NHCs with main-group elements which resulted in modification of the NHC. Many of these reactions lead to ring expansion and the formation of six-membered heterocyclic rings involving insertion of the heteroatom into the C-N bond and migration of hydrides, phenyl groups or boron-containing fragments. Furthermore, a few related NHC rearrangements were observed some decades ago. In this Perspective, we summarise the history of NHC ring expansion reactions from the 1960s till the present.

  18. Stellar Activity at the End of the Main Sequence: GHRS Observations of the M8 Ve Star VB 10

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.; Wood, Brian E.; Brown, Alexander; Giampapa, Mark S.; Ambruster, Carol

    1995-01-01

    We present Goddard High Resolution Spectrograph observations of the M8 Ve star VB 10 (equal to G1 752B), located very near the end of the stellar main sequence, and its dM3.5 binary companion G1 752A. These coeval stars provide a test bed for studying whether the outer atmospheres of stars respond to changes in internal structure as stars become fully convective near mass 0.3 solar mass (about spectral type M5), where the nature of the stellar magnetic dynamo presumably changes, and near the transition from red to brown dwarfs near mass 0.08 solar mass (about spectral type M9), when hydrogen burning ceases at the end of the main sequence. We obtain upper limits for the quiescent emission of VB 10 but observe a transition region spectrum during a large flare, which indicates that some type of magnetic dynamo must be present. Two indirect lines of evidence-scaling from the observed X-ray emission and scaling from a time-resolved flare on AD Leo suggest that the fraction of the stellar bolometric luminosity that heats the transition region of VB 10 outside of obvious flares is comparable to, or larger than, that for G1 752A. This suggests an increase in the magnetic heating rates, as measured by L(sub line)/L(sub bol) ratios, across the radiative/convective core boundary and as stars approach the red/brown dwarf boundary. These results provide new constraints for dynamo models and models of coronal and transition-region heating in late-type stars.

  19. Comparative Localization and Functional Activity of the Main Hepatobiliary Transporters in HepaRG Cells and Primary Human Hepatocytes

    PubMed Central

    Bachour-El Azzi, Pamela; Sharanek, Ahmad; Burban, Audrey; Li, Ruoya; Guével, Rémy Le; Abdel-Razzak, Ziad; Stieger, Bruno; Guguen-Guillouzo, Christiane; Guillouzo, André

    2015-01-01

    The role of hepatobiliary transporters in drug-induced liver injury remains poorly understood. Various in vivo and in vitro biological approaches are currently used for studying hepatic transporters; however, appropriate localization and functional activity of these transporters are essential for normal biliary flow and drug transport. Human hepatocytes (HHs) are considered as the most suitable in vitro cell model but erratic availability and inter-donor functional variations limit their use. In this work, we aimed to compare localization of influx and efflux transporters and their functional activity in differentiated human HepaRG hepatocytes with fresh HHs in conventional (CCHH) and sandwich (SCHH) cultures. All tested influx and efflux transporters were correctly localized to canalicular [bile salt export pump (BSEP), multidrug resistance-associated protein 2 (MRP2), multidrug resistance protein 1 (MDR1), and MDR3] or basolateral [Na+-taurocholate co-transporting polypeptide (NTCP) and MRP3] membrane domains and were functional in all models. Contrary to other transporters, NTCP and BSEP were less abundant and active in HepaRG cells, cellular uptake of taurocholate was 2.2- and 1.4-fold and bile excretion index 2.8- and 2.6-fold lower, than in SCHHs and CCHHs, respectively. However, when taurocholate canalicular efflux was evaluated in standard and divalent cation-free conditions in buffers or cell lysates, the difference between the three models did not exceed 9.3%. Interestingly, cell imaging showed higher bile canaliculi contraction/relaxation activity in HepaRG hepatocytes and larger bile canaliculi networks in SCHHs. Altogether, our results bring new insights in mechanisms involved in bile acids accumulation and excretion in HHs and suggest that HepaRG cells represent a suitable model for studying hepatobiliary transporters and drug-induced cholestasis. PMID:25690737

  20. Functional ultrasound imaging reveals different odor-evoked patterns of vascular activity in the main olfactory bulb and the anterior piriform cortex.

    PubMed

    Osmanski, B F; Martin, C; Montaldo, G; Lanièce, P; Pain, F; Tanter, M; Gurden, H

    2014-07-15

    Topographic representation of the outside world is a key feature of sensory systems, but so far it has been difficult to define how the activity pattern of the olfactory information is distributed at successive stages in the olfactory system. We studied odor-evoked activation patterns in the main olfactory bulb and the anterior piriform cortex of rats using functional ultrasound (fUS) imaging. fUS imaging is based on the use of ultrafast ultrasound scanners and detects variations in the local blood volume during brain activation. It makes deep brain imaging of ventral structures, such as the piriform cortex, possible. Stimulation with two different odors (hexanal and pentylacetate) induced the activation of odor-specific zones that were spatially segregated in the main olfactory bulb. Interestingly, the same odorants triggered the activation of the entire anterior piriform cortex, in all layers, with no distinguishable odor-specific areas detected in the power Doppler images. These fUS imaging results confirm the spatial distribution of odor-evoked activity in the main olfactory bulb, and furthermore, they reveal the absence of such a distribution in the anterior piriform cortex at the macroscopic scale in vivo.

  1. Optical absorptions in ZnO/a-Si distributed Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Chen, Aqing; Chen, Zhian; Zhu, Kaigui; Ji, Zhenguo

    2017-01-01

    The distributed Bragg reflectors (DBRs) consisting of alternating layers of ZnO and heavy doped amorphous silicon (a-Si) have been fabricated by magnetron sputtering. It is novel to find that the optical absorptions exist in the stopband of the DBRs, and that many discrete strong optical absorption peaks exist in the wavelength range of visible to near-infrared. The calculated results by FDTD show that the absorptions in the stopband mainly exist in the first a-Si layer, and that the light absorbed by other a-Si layers inside contributes to the two absorption peaks in near-infrared range. The strong absorptions ranged from visible to infrared open new possibilities to the enhancement of the performance of amorphous silicon solar cells.

  2. Large Deployable Reflector Science and Technology Workshop. Volume 2: Scientific Rationale and Technology Requirements

    NASA Technical Reports Server (NTRS)

    Hollenbach, D. (Editor)

    1983-01-01

    The scientific rationale for the large deployable reflector (LDR) and the overall technological requirements are discussed. The main scientific objectives include studies of the origins of planets, stars and galaxies, and of the ultimate fate of the universe. The envisioned studies require a telescope with a diameter of at least 20 m, diffraction-limited to wavelengths as short as 30-50 micron. In addition, light-bucket operation with 1 arcsec spatial resolution in the 2-4 microns wavelength region would be useful in studies of high-redshifted galaxies. Such a telescope would provide a large increase in spectroscopic sensitivity and spatial resolving power compared with existing or planned infrared telescopes.

  3. Cassegrainian/Gregorian-type null correctors for surface measurements of radio telescope reflectors.

    PubMed

    Greve, A

    1997-08-01

    The (sub)millimeter wavelength radio observatory of the next generation will probably be an interferometer array of some 50 telescopes with parabolic reflectors 10-15 m in diameter. At this scale of mass production it is convenient to have at hand for workshop assembly a reflector surface measurement technique that is precise and easy to operate. We discuss the possibility of reflector measurements based on 10.6-microm CO2 laser interferometry using Cassegrainian/Gregorian-type null correctors.

  4. An array fed dual reflector antenna for limited sector electronic beam scanning

    NASA Astrophysics Data System (ADS)

    Pearson, R. A.; Davies, D. E. N.; Cullen, A. L.

    A dual reflector configuration capable of electronic beam deflection is described. It was found that, in two dimensions, the performance of a confocal reflector arrangement can be significantly improved by shaping the subreflector. A computationally efficient method for analyzing the three-dimensional antenna has been demonstrated which combines an accurate array representation with a minimal amount of ray tracing to overcome the difficulties of modeling the array fed dual reflector antenna.

  5. Radar Cross-Section Measurements of V22 Blade Tip with and without LLNL Tipcap Reflector

    SciTech Connect

    Poland, D; Simpson, R

    2000-07-01

    It is desired to quantify the effect, in terms of radar cross-section (RCS), of the addition of a small aluminum reflector to the end of the V22 blades. This reflector was designed and manufactured in order to facilitate blade lag measurements by the 95 GHz Lawrence Livermore National Laboratory (LLNL) Radar Blade Tracker (RBT) system. The reflector used in these measurements was designed and fabricated at LLNL and is pictured in Figure 1.

  6. Acaricidal activity of Thymus vulgaris oil and its main components against Tyrophagus putrescentiae, a stored food mite.

    PubMed

    Jeong, E Y; Lim, J H; Kim, H G; Lee, H S

    2008-02-01

    The acaricidal activities of compounds derived from Thymus vulgaris (thyme) oil against Tyrophagus putrescentiae were assessed using an impregnated fabric disk bioassay, and were compared with those of the synthetic acaricides, benzyl benzoate and N,N-diethyl-m-toluamide. The observed responses differed according to dosage and chemical components. The 50% lethal dose (LD50) value of the T. vulgaris oil against T. putrescentiae was 10.2 microg/cm2. Biologically active constituents derived from T. vulgaris oil were purified by using silica gel chromatography and high-performance liquid chromatography. The structures of acaricidal components were analyzed by gas chromatography-mass spectrometry, 1H nuclear magnetic resonance (NMR), 13C NMR, 1H-13C COSY-NMR, and DEPT-NMR spectra, and were subsequently identified as carvacrol and thymol. Carvacrol was the most toxic compound with LD50 values (4.5 microg/cm2) significantly different from thymol (11.1 microg/cm2), benzyl benzoate (11.3 microg/cm2), and N,N-diethyl-m-toluamide (13.9 microg/cm2). Linalool was as toxic as was N,N-diethyl-m-toluamide. The lower LD50 of carvacrol indicates that it may be the major contributor of the toxicity of T. vulagaris oil against the stored food mite, although it only constitutes 14.2% of the oil. From this point of view, carvacrol and thymol can be very useful as potential control agents against stored food mite.

  7. Insecticidal activity of essential oil of Carum Carvi fruits from China and its main components against two grain storage insects.

    PubMed

    Fang, Rui; Jiang, Cai Hong; Wang, Xiu Yi; Zhang, Hai Ming; Liu, Zhi Long; Zhou, Ligang; Du, Shu Shan; Deng, Zhi Wei

    2010-12-20

    During our screening program for agrochemicals from Chinese medicinal herbs and wild plants, the essential oil of Carum carvi fruits was found to possess strong contact toxicity against Sitophilus zeamais and Tribolium castaneum adults, with LD₅₀ values of 3.07 and 3.29 μg/adult, respectively, and also showed strong fumigant toxicity against the two grain storage insects with LC₅₀ values of 3.37 and 2.53 mg/L, respectively. The essential oil obtained by hydrodistillation was investigated by GC and GC-MS. The main components of the essential oil were identified to be (R)-carvone (37.98%) and D-limonene (26.55%) followed by α-pinene (5.21), cis-carveol (5.01%) and β-myrcene (4.67%). (R)-Carvone and D-limonene were separated and purified by silica gel column chromatography and preparative thin layer chromatography, and further identified by means of physicochemical and spectrometric analysis. (R)-Carvone and D-limonene showed strong contact toxicity against S. zeamais (LD₅₀ = 2.79 and 29.86 μg/adult) and T. castaneum (LD₅₀ = 2.64 and 20.14 μg/adult). (R)-Carvone and D-limonene also possessed strong fumigant toxicity against S. zeamais (LC₅₀ = 2.76 and 48.18 mg/L) and T. castaneum adults (LC₅₀ = 1.96 and 19.10 mg/L).

  8. Studies on the antimicrobial activity and brine shrimp toxicity of Zeyheria tuberculosa (Vell.) Bur. (Bignoniaceae) extracts and their main constituents

    PubMed Central

    Bastos, Maria Lysete A; Lima, Maria Raquel F; Conserva, Lucia M; Andrade, Vânia S; Rocha, Eliana MM; Lemos, Rosangela PL

    2009-01-01

    Background Due to the indiscriminate use of antimicrobial drugs, the emergence of human pathogenic microorganisms resistant to major classes of antibiotics has been increased and has caused many clinical problems in the treatment of infectious diseases. Thus, the aim of this study was to evaluate for the first time the in vitro antimicrobial activity and brine shrimp lethality of extracts and isolated compounds from Zeyheria tuberculosa (Vell.) Bur., a species used in Brazilian folk medicine for treatment of cancer and skin diseases. Methods Using the disc diffusion method, bioautography assay and brine shrimp toxicity test (Artemia salina Leach), we studied the antimicrobial activity and lethality of extracts and isolated compounds against three microorganisms strains, including Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria and yeasts (Candida albicans). Results In this study, the extracts inhibited S. aureus (8.0 ± 0.0 to 14.0 ± 0.0 mm) and C. albicans (15.3 ± 0.68 to 25.6 ± 0.4 mm) growth. In the brine shrimp test, only two of them showed toxic effects (LC50 29.55 to 398.05 μg/mL) and some extracts were non-toxic or showed weak lethality (LC50 705.02 to > 1000 μg/mL). From these extracts, four flavones [5,6,7,8-tetramethoxyflavone (1), 5,6,7-trimethoxyflavone (2), 4'-hydroxy-5,6,7,8-tetramethoxyflavone (3), and 4'-hydroxy-5,6,7-trimethoxyflavone (4)] were isolated through bioassay-guided fractionation and identified based on the 1D and 2D NMR spectral data. By bioautography assays, compounds 1 [S. aureus (16.0 ± 0.0 mm) and C. albicans (20.0 ± 0.0 mm)] and 3 [S. aureus (10.3 ± 0.6 mm) and C. albicans (19.7 ± 0.6 mm)] inhibited both microorganisms while 2 inhibited only S. aureus (11.7 ± 0.6 mm). Compound 4 did not restrain the growth of any tested microorganism. Conclusion Our results showed that extracts and isolated flavones from Z. tuberculosa may be particularly useful against two pathogenic

  9. Demonstration of a single-crystal reflector-filter for enhancing slow neutron beams

    NASA Astrophysics Data System (ADS)

    Muhrer, G.; Schönfeldt, T.; Iverson, E. B.; Mocko, M.; Baxter, D. V.; Hügle, Th.; Gallmeier, F. X.; Klinkby, E. B.

    2016-09-01

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystal reflector-filter at a reflected neutron source and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. This finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.

  10. Structural Characterization of a Mo/Ru/Si Extreme Ultraviolet (EUV) Reflector by Optical Modeling

    NASA Astrophysics Data System (ADS)

    Kang, In-Yong; Kim, Tae Geun; Lee, Seung Yoon; Ahn, Jinho; Chung, Yong-Chae

    2004-06-01

    The performance of a multilayer extreme ultraviolet (EUV) reflector has a direct bearing on process throughput and the cost of new technology. Using measured data from an experimentally manufactured reflector, we intend, in this work, to show that the reflectivity of the Bragg reflector can be characterized by using structural parameters such as the d-spacing, density, thicknesses of the interdiffusion layers and oxidation layer. This quantitative analysis of the reflectivity derived from the structural parameters can be utilized to optimize the optical properties of the existing Mo/Ru/Si system and to provide fundamental insights into the science involved in a Bragg EUV reflector.

  11. Surface measuring technique. [using a laser to scan the surface of a reflector

    NASA Technical Reports Server (NTRS)

    Spiers, R. B., Jr.

    1980-01-01

    Measurement of the surface contour of a large electrostatically formed concave reflector using a modified Foucault or knife edge test is described. The curve of the actual electrostatically formed reflector surface is compared to a curve representing a reference sphere. Measurements of surface slope and deviation are calculated every 15 cm along the reflector's horizontal and vertical diameters. Characterization of surface roughness on a small scale compared to the laser spot size at the reflector are obtained from the increased laser spot size at a distant projection screen.

  12. Demonstration of a Single-Crystal Reflector-Filter for Enhancing Slow Neutron Beams

    DOE PAGES

    Muhrer, Guenter; Schönfeldt, Troels; Iverson, Erik B.; ...

    2016-06-14

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystalmore » reflector-filter and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. Ultimately, this finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.« less

  13. Demonstration of a Single-Crystal Reflector-Filter for Enhancing Slow Neutron Beams

    SciTech Connect

    Muhrer, Guenter; Schönfeldt, Troels; Iverson, Erik B.; Mocko, Michal; Baxter, David V.; Hügle, Thomas; Gallmeier, Franz X.; Klinkby, Esben

    2016-06-14

    The cold polycrystalline beryllium reflector-filter concept has been used to enhance the cold neutron emission of cryogenic hydrogen moderators, while suppressing the intermediate wavelength and fast neutron emission at the same time. While suppressing the fast neutron emission is often desired, the suppression of intermediate wavelength neutrons is often unwelcome. It has been hypothesized that replacing the polycrystalline reflector-filter concept with a single-crystal reflector-filter concept would overcome the suppression of intermediate wavelength neutrons and thereby extend the usability of the reflector-filter concept to shorter but still important wavelengths. In this paper we present the first experimental data on a single-crystal reflector-filter and compare experimental results with hypothesized performance. We find that a single-crystal reflector-filter retains the long-wavelength benefit of the polycrystalline reflector-filter, without suffering the same loss of important intermediate wavelength neutrons. Ultimately, this finding extends the applicability of the reflector-filter concept to intermediate wavelengths, and furthermore indicates that the reflector-filter benefits arise from its interaction with fast (background) neutrons, not with intermediate wavelength neutrons of potential interest in many types of neutron scattering.

  14. A method to design blended rolled edges for compact range reflectors

    NASA Technical Reports Server (NTRS)

    Gupta, Inder J.; Burnside, Walter D.

    1989-01-01

    A method to design blended rolled edges for arbitrary rim shape compact range reflectors is presented. The reflectors may be center-fed or offset-fed. The method leads to rolled edges with minimal surface discontinuities. It is shown that the reflectors designed using the prescribed method can be defined analytically using simple expressions. A procedure to obtain optimum rolled edges parameter is also presented. The procedure leads to blended rolled edges that minimize the diffracted fields emanating from the junction between the paraboloid and the rolled edge surface while satisfying certain constraints regarding the reflector size and the minimum operating frequency of the system.

  15. Enantioselective cyclopolymerization of 1,5-hexadiene catalyzed by chiral zirconocenes: A novel strategy for the synthesis of optically active polymers with chirality in the main chain

    SciTech Connect

    Coates, G.W.; Waymouth, R.M. )

    1993-01-13

    Enantioselective cyclopolymerization represents a novel strategy for the synthesis of optically active main-chain chiral polymers. Cyclopolymerization of 1,5-hexadiene using the optically active catalyst precursor, (R,R)-(EBTHI)ZrBINOL ((R,R)-1) [EBTHI = ethylene-1,2-bis([eta][sup 5]-4,5,6,7-tetrahydro-1-indenyl); BINOL = 1,1[prime]-bi-2-naphtholate], yields optically active poly(methylene-1,3-cyclopentane) (PMCP) with a molar optical rotation of [[Phi

  16. Epidihydropinidine, the main piperidine alkaloid compound of Norway spruce (Picea abies) shows promising antibacterial and anti-Candida activity.

    PubMed

    Fyhrquist, Pia; Virjamo, Virpi; Hiltunen, Eveliina; Julkunen-Tiitto, Riitta

    2017-03-01

    This study reports for the first time promising antibacterial and antifungal effects of epidihydropinidine, the major piperidine alkaloid in the needles and bark of Norway spruce, Picea abies (L.) Karsten. Epidihydropinidine was growth inhibitory against all bacterial and fungal strains used in our investigation, showing the lowest MIC value of 5.37μg/mL against Pseudomonas aeruginosa, Enterococcus faecalis, Candida glabrata and C. albicans. Epidihydropinidine was nearly three times more active than tetracycline against P. aeruginosa and E. faecalis. Promising antibacterial effects were also recorded against Staphylococcus aureus and Bacillus cereus (MIC 10.75μg/mL) as well as against Salmonella enterica (MIC and MBC 43μg/mL). Our preliminary results suggest that epidihydropinidine as well related alkaloids of Norway spruce could be powerful candidates for new antibiotics and for preventing food spoilage.

  17. Compensation for Phase Anisotropy of a Metal Reflector

    NASA Technical Reports Server (NTRS)

    Hong, John

    2007-01-01

    A method of compensation for the polarization- dependent phase anisotropy of a metal reflector has been proposed. The essence of the method is to coat the reflector with multiple thin alternating layers of two dielectrics that have different indices of refraction, so as to introduce an opposing polarization-dependent phase anisotropy. The anisotropy in question is a phenomenon that occurs in reflection of light at other than normal incidence: For a given plane wave having components polarized parallel (p) and perpendicular (s) to the plane of incidence, the phase of s-polarized reflected light differs from the phase p-polarized light by an amount that depends on the angle of incidence and the complex index of refraction of the metal. The magnitude of the phase difference is zero at zero angle of incidence (normal incidence) and increases with the angle of incidence. This anisotropy is analogous to a phase anisotropy that occurs in propagation of light through a uniaxial dielectric crystal. In such a case, another uniaxial crystal that has the same orientation but opposite birefringence can be used to cancel the phase anisotropy. Although it would be difficult to prepare a birefringent material in a form suitable for application to the curved surface of a typical metal reflector in an optical instrument, it should be possible to effect the desired cancellation of phase anisotropy by exploiting the form birefringence of multiple thin dielectric layers. (The term "form birefringence" can be defined loosely as birefringence arising, in part, from a regular array of alternating subwavelength regions having different indices of refraction.)

  18. Reflectance and unsteady temperature distribution of diffuse reflectors

    NASA Technical Reports Server (NTRS)

    Weston, K. C.; Reddy, R. S.

    1973-01-01

    The applicability of a previously derived solution of the Kubelka-Munk differential equations for the reflectance of an absorbing and scattering material for the case of a zero absorption coefficient to the description of the reflectance of a weakly absorbing, highly scattering material is examined. A solution for the transient heating of a one-dimensional volume reflector is obtained, and the error incurred in the use of the zero absorption coefficient solution is assessed for early times appropriate to the entry heat protection system application. It is found that the small difference in reflectance causes a significant difference in internal temperature.

  19. Recent BeO-reflector-controlled reactor experiments in ZPPR

    SciTech Connect

    McFarlane, H.F.; Brumbach, S.B.; Carpenter, S.G.; Collins, P.J.; McKnight, R.D.

    1986-01-01

    Integral reactor physics measurements were performed on a BeO-reflected fast reactor assembly in the ZPPR facility during January and February of 1985. The measurements emphasized power distributions and reflector control worths in two different critical states. The measurements have been analyzed using three-dimensional deterministic and Monte Carlo methods and the ENDF/B-V.2 nuclear data library. Together the measurements and analyses form a modern, reliable, benchmark data set for testing calculational methods that will be used in predicting some of the design parameters for future space reactors.

  20. Reflector and Shield Material Properties for Project Prometheus

    SciTech Connect

    J. Nash

    2005-11-02

    This letter provides updated reflector and shield preliminary material property information to support reactor design efforts. The information provided herein supersedes the applicable portions of Revision 1 to the Space Power Program Preliminary Reactor Design Basis (Reference (a)). This letter partially answers the request in Reference (b) to provide unirradiated and irradiated material properties for beryllium, beryllium oxide, isotopically enriched boron carbide ({sup 11}B{sub 4}C) and lithium hydride. With the exception of {sup 11}B{sub 4}C, the information is provided in Attachments 1 and 2. At the time of issuance of this document, {sup 11}B{sub 4}C had not been studied.

  1. VSHOT: a tool for characterizing large, imprecise reflectors

    SciTech Connect

    Jones, S.A.; Neal, D.R.; Gruetzner, J.K.; Houser, R.M.; Edgar, R.M.; Wendelin, T.J.

    1996-11-01

    A prototype Video Scanning Hartmann Optical Tester (VSHOT) has been developed to characterize the optics of dish-type solar concentrators. VSHOT is a flexible platform that may characterize any large reflector with a focal length over diameter ratio (f{number_sign}) greater than 0. 45, and RMS optical error in the 0. I - I 0 milliradian range. The VSHOT hardware, software, and operation are described. Measurement uncertainty and preliminary test results are discussed. Another potential application being explored for the VSHOT is the quality assurance of slumped-glass automobile windshields. Preliminary test results from a reference optic and a section of a windshield are presented.

  2. Giant Bragg Wavelength Tuning of Tunable Hollow Waveguide Bragg Reflector

    NASA Astrophysics Data System (ADS)

    Sakurai, Yasuki; Matsutani, Akihiro; Sakaguchi, Takahiro; Koyama, Fumio

    2005-09-01

    We demonstrate a giant Bragg wavelength tuning with a grating loaded hollow waveguide Bragg reflector. An air-core thickness change of a hollow waveguide enables us to achieve a large propagation constant change over few tens percent, which would be useful for various tunable optical devices. Our observed Bragg-wavelength tuning range is over 160 nm at an air-core thickness change from 10.7 to 1.8 μm, which corresponds to a propagation constant change of over 10%. This is the record large tuning value ever reported in conventional tuning schemes such as thermo-optic or electro-optic effects.

  3. Air-core hollow optical waveguides with omnidirectional reflectors

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Shou; Chen, Chii-Chang

    2006-04-01

    We have designed and fabricated a hollow optical waveguide with omnidirectional reflectors (ODRs) on a silicon substrate. The pattern is defined by photolithography on a (100) silicon wafer. The groove is etched by inductive coupled plasma. Plasma-enhanced chemical vapor deposition technology is used to deposit six-pair Si/SiO2 (0.111/0.258 µm) multilayer stacks on the sample. Finally, the top of the sample is covered with an identical ODR. Hence, the light is confined in a hollow waveguide.

  4. Optical device with low electrical and thermal resistance bragg reflectors

    DOEpatents

    Lear, Kevin L.

    1996-01-01

    A compound-semiconductor optical device and method. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors.

  5. Optical device with low electrical and thermal resistance Bragg reflectors

    DOEpatents

    Lear, K.L.

    1996-10-22

    A compound-semiconductor optical device and method are disclosed. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors. 16 figs.

  6. User's manual for semi-circular compact range reflector code

    NASA Technical Reports Server (NTRS)

    Gupta, Inder J.; Burnside, Walter D.

    1986-01-01

    A computer code was developed to analyze a semi-circular paraboloidal reflector antenna with a rolled edge at the top and a skirt at the bottom. The code can be used to compute the total near field of the antenna or its individual components at a given distance from the center of the paraboloid. Thus, it is very effective in computing the size of the sweet spot for RCS or antenna measurement. The operation of the code is described. Various input and output statements are explained. Some results obtained using the computer code are presented to illustrate the code's capability as well as being samples of input/output sets.

  7. Accretion and outflow activity on the late phases of pre-main-sequence evolution. The case of RZ Piscium

    NASA Astrophysics Data System (ADS)

    Potravnov, I. S.; Mkrtichian, D. E.; Grinin, V. P.; Ilyin, I. V.; Shakhovskoy, D. N.

    2017-03-01

    RZ Psc is an isolated high-latitude post-T Tauri star that demonstrates a UX Ori-type photometric activity. The star shows very weak spectroscopic signatures of accretion, but at the same time possesses the unusual footprints of the wind in Na i D lines. In the present work we investigate new spectroscopic observations of RZ Psc obtained in 2014 during two observation runs. We found variable blueshifted absorption components (BACs) in lines of the other alcali metals, K i 7699 Å and Ca ii IR triplet. We also confirmed the presence of a weak emission component in the Hα line, which allowed us to estimate the mass accretion rate on the star as Ṁ ≤ 7 × 10-12M⊙ yr-1. We could not reveal any clear periodicity in the appearance of BACs in sodium lines. Nevertheless, the exact coincidence of the structure and velocities of the Na i D absorptions observed with the interval of about one year suggests that such a periodicity should exist.

  8. Phenotyping studies to assess the effects of phytopharmaceuticals on in vivo activity of main human cytochrome p450 enzymes.

    PubMed

    Zadoyan, Gregor; Fuhr, Uwe

    2012-09-01

    The extensive use of herbal drugs and their multiple components and modes of action suggests that they may also cause drug interactions by changing the activity of human cytochrome P450 enzymes. The purpose of the present review is to present the available data for the top 14 herbal drug sales in the U. S. Studies describing the effects of herbal drugs on phenotyping substrates for individual CYPs were identified by a comprehensive MEDLINE search. Drugs included Allium sativum (Liliaceae), Echinacea purpurea (Asteraceae), Serenoa repens (Arecaceae), Ginkgo biloba (Ginkgoaceae), Vaccinium macrocarpon (Ericaceae), Glycine max (Fabaceae), Panax ginseng (Araliaceae), Actea racemosa (Ranunculaceae), Hypericum perforatum (Hypericaceae), Silybum marianum (Asteraceae), Camellia sinensis (Theaceae), Valeriana officinalis (Valerianaceae), Piper methysticum (Piperaceae), and Hydrastis canadensis (Ranunculaceae) preparations. We identified 70 clinical studies in 69 publications. The majority of the herbal drugs appeared to have no clear effects on most of the CYPs examined. If there was an effect, there was mild inhibition in almost all cases, as seen with garlic or kava effects on CYP2E1 and with soybean components on CYP1A2. The most pronounced effects were induction of CYP3A and other CYPs by St. John's wort and the inhibitory effect of goldenseal on CYP3A and CYP2D6, both being borderline between mild and moderate in magnitude. With the exceptions of St.John's wort and goldenseal, the information currently available suggests that concomitant intake of the herbal drugs addressed here is not a major risk for drugs that are metabolized by CYPs.

  9. Innovative design of parabolic reflector light guiding structure

    NASA Astrophysics Data System (ADS)

    Whang, Allen J.; Tso, Chun-Hsien; Chen, Yi-Yung

    2008-02-01

    Due to the idea of everlasting green architecture, it is of increasing importance to guild natural light into indoors. The advantages are multifold - to have better color rendering index, excellent energy savings from environments viewpoints and make humans more healthy, etc. Our search is to design an innovative structure, to convert outdoor sun light impinges on larger surfaces, into near linear light beam sources, later convert this light beam into near point sources which enters the indoor spaces then can be used as lighting sources indoors. We are not involved with the opto-electrical transformation, to the guild light into to the building, to perform the illumination, as well as the imaging function. Because non-imaging optics, well known for apply to the solar concentrators, that can use non-imaging structures to fulfill our needs, which can also be used as energy collectors in solar energy devices. Here, we have designed a pair of large and small parabolic reflector, which can be used to collect daylight and change area from large to small. Then we make a light-guide system that is been designed by us use of this parabolic reflector to guide the collection light, can pick up the performance for large surface source change to near linear source and a larger collection area.

  10. Concentricity calibration of photogrammetry retro-reflector target

    NASA Astrophysics Data System (ADS)

    Wei, Hengzheng; Wang, Weinong; Pei, Limei; Ren, Guoying

    2016-11-01

    Close range digital photogrammetry is being widely used in industrial measurements. The measurements are usually carried out with a mobile retro-reflector target, which is consists of a shaft and reflective target fixed in the center of the shaft. When the center of the target and the axis of the shaft is not consistent, it will introduce measurement error. Therefore, the concentricity of target is an important parameter for the measurement results. To achieve the concentricity of retro-reflector target a multi-sensor coordinate measurement machine with imaging probe and touch probe is used. In this combined measurement system the touch probe measure the axis of the shaft, and imaging probe measure the center of reflective target. An artifact is designed to evaluate the performance of combined system. This artifact is defined as a sharp edged hole in a metal plate. It is suitable to measure with touch probe as well as imaging probe. The touch probe measures 25 points on the hole and then with the imaging probe. With all the points measured by two kinds of probe the evaluation parameters including combination size error, form error and location error are calculated. These parameters are consistent with the ISO standard 10360-9. It indicates that combined measurement uncertainty is 3.2 microns which can meet the calibration requirements of target concentricity.

  11. Some Broadband Calculated RF Scatter from the Trihedral Corner Reflector

    NASA Astrophysics Data System (ADS)

    Mokole, E. L.; Gold, B. T.; Taylor, D. J.; Sarkar, T. K.; Hansen, J. P.

    To understand the target-like artifacts in radar returns called sea spikes 1 that are induced by ocean scatter,2 the WIPL-D3 and WIPL-DP4 electromagnetics codes are used to calculate monostatic and bistatic radar cross sections (RCSs) of a trihedral comer reflector at 1.5, 3.8, and 7 GHz for vertically and horizontally polarized fields. These computations are part of a larger effort to provide theoretical comparisons for recent scatter data from a 1-m trihedral reflector that was collected over 1.9 to 11.5 GHz in the open ocean with a short-pulse ultrawideband (UWB) system. Over the last eight years, this UWB experimental radar, called the microwave microscope (MWM), has been used in a series of measurements at the Atlantic Underwater Test and Experiment Center (AUTEC) in the Bahamas to investigate the low-elevation (grazing angles less than 4°)scatter of RF signals from the open ocean in an attempt to understand and mitigate the sea-spike phenomenon.

  12. Strong reflector-based beamforming in ultrasound medical imaging.

    PubMed

    Szasz, Teodora; Basarab, Adrian; Kouamé, Denis

    2016-03-01

    This paper investigates the use of sparse priors in creating original two-dimensional beamforming methods for ultrasound imaging. The proposed approaches detect the strong reflectors from the scanned medium based on the well known Bayesian Information Criteria used in statistical modeling. Moreover, they allow a parametric selection of the level of speckle in the final beamformed image. These methods are applied on simulated data and on recorded experimental data. Their performance is evaluated considering the standard image quality metrics: contrast ratio (CR), contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). A comparison is made with the classical delay-and-sum and minimum variance beamforming methods to confirm the ability of the proposed methods to precisely detect the number and the position of the strong reflectors in a sparse medium and to accurately reduce the speckle and highly enhance the contrast in a non-sparse medium. We confirm that our methods improve the contrast of the final image for both simulated and experimental data. In all experiments, the proposed approaches tend to preserve the speckle, which can be of major interest in clinical examinations, as it can contain useful information. In sparse mediums we achieve a highly improvement in contrast compared with the classical methods.

  13. Simulation requirements for the Large Deployable Reflector (LDR)

    NASA Technical Reports Server (NTRS)

    Soosaar, K.

    1984-01-01

    Simulation tools for the large deployable reflector (LDR) are discussed. These tools are often the transfer function variety equations. However, transfer functions are inadequate to represent time-varying systems for multiple control systems with overlapping bandwidths characterized by multi-input, multi-output features. Frequency domain approaches are the useful design tools, but a full-up simulation is needed. Because of the need for a dedicated computer for high frequency multi degree of freedom components encountered, non-real time smulation is preferred. Large numerical analysis software programs are useful only to receive inputs and provide output to the next block, and should be kept out of the direct loop of simulation. The following blocks make up the simulation. The thermal model block is a classical heat transfer program. It is a non-steady state program. The quasistatic block deals with problems associated with rigid body control of reflector segments. The steady state block assembles data into equations of motion and dynamics. A differential raytrace is obtained to establish a change in wave aberrations. The observation scene is described. The focal plane module converts the photon intensity impinging on it into electron streams or into permanent film records.

  14. High power GaInAs lasers with distributed Bragg reflectors

    NASA Technical Reports Server (NTRS)

    O'Brien, S.; Parke, R.; Welch, D. F.; Mehuys, D.; Scifres, D.

    1992-01-01

    Single-mode strained-layer lasers have been fabricated which use buried second-order gratings for distributed Bragg reflectors. The lasers contain a strained GaInAs quantum well in the active region and operate in an edge emitting fashion with CW powers in excess of 110 mW. Single longitudinal and transverse mode operation is maintained at about 971.9 nm up to 42 mW. Total power conversion efficiencies as high as 28 percent have been observed. The longitudinal and transverse mode behavior is stable under 90 percent amplitude modulation with 50 percent duty cycle pulses at 10 kHz and 10 MHz. Preliminary life-test data at 40 C also indicate room temperature lifetimes in excess of 45,000 hours.

  15. Performance Enhancement in Plasmonic Photoconductive Terahertz Electronics by Incorporating Distributed Bragg Reflectors

    NASA Astrophysics Data System (ADS)

    Hemmati, Soroosh

    Terahertz optoelectronics have shown significant promise in the development and enhancement of technologies in chemical identification, biological sensing, and medical imaging. The practical advancement of such devices, however, has been hindered by the characteristics of the frequency range, 0.3 to 3 THz in the electromagnetic radiation spectrum. Presented here is a demonstration of the significant advancements possible in creating efficient and ultra-fast plasmonic THz sources by incorporating an optical cavity using a distributed Bragg reflector (DBR). Plasmonic electrodes enable increased transmission of photons into a GaAs photo-absorbing substrate, and the DBR enhances the quantum efficiency of the device by creating an optical cavity which allows for nearly 100% of the incoming light getting absorbed in the active GaAs layer.

  16. WWER-1000 core and reflector parameters investigation in the LR-0 reactor

    SciTech Connect

    Zaritsky, S. M.; Alekseev, N. I.; Bolshagin, S. N.; Riazanov, D. K.; Lichadeev, V. V.; Ocmera, B.; Cvachovec, F.

    2006-07-01

    Measurements and calculations carried out in the core and reflector of WWER-1000 mock-up are discussed: - the determination of the pin-to-pin power distribution in the core by means of gamma-scanning of fuel pins and pin-to-pin calculations with Monte Carlo code MCU-REA and diffusion codes MOBY-DICK (with WIMS-D4 cell constants preparation) and RADAR - the fast neutron spectra measurements by proton recoil method inside the experimental channel in the core and inside the channel in the baffle, and corresponding calculations in P{sub 3}S{sub 8} approximation of discrete ordinates method with code DORT and BUGLE-96 library - the neutron spectra evaluations (adjustment) in the same channels in energy region 0.5 eV-18 MeV based on the activation and solid state track detectors measurements. (authors)

  17. [The main results of expert activities in the forensic biological departments of the bureau of forensic medical expertise of the Russian Federation for 2009].

    PubMed

    Gusarov, A A

    2011-01-01

    This paper reports the main results of expert activities in the forensic biological departments of the Bureau of Forensic Medical Expertise of the Russian Federation for 2009. Analysis of expert data is supplemented by the comparison of the efficacy of the methods applied for the purpose of forensic medical studies. The information about the staff composition, material and technical support of the forensic biological departments is presented. A number of drawbacks have been revealed in the work of the forensic biological departments; recommendations are proposed for the improvement of their activities.

  18. [Studies on effects of Achyranthes bidentata on tongsaimai pellets main active ingredients chlorogenic acid, isoliquiritin, harpagoside and glycyrrhizin in vivo pharmacokinetics].

    PubMed

    Cheng, Jian; Di, Liu-Qing; Shan, Jin-Jun; Zhao, Xiao-Li; Kang, An; Bi, Xiao-Lin; Li, Jun-Song

    2014-04-01

    To study on the effects of Achyranthes bidentata on Tongsaimai pellets main active ingredients chlorogenic acid, isoliquiritin, harpagoside and glycyrrhizin in rats in vivo pharmacokinetic behaviors, a method for the simultaneous determination of chlorogenic acid, isoliquiritin, harpagoside and liquiritigenin in rat plasma was established by UPLC-MS/MS. The analysis was performed on a waters Acquity BEH C18 column (2.1 mm x 100 mm, 1.7 microm) with the mixture of acetonitrile and 0.1% formic acid/water as mobile phase, and the gradient elution at a flow rate of 0.3 mL x min(-1). The analytes were detected by tandem mass spectrometry with the electrospray ionization (ESI) source and in the multiple reaction monitoring (MRM) mode. It turned out that the analytes of Tongsaimai pellets groups C(max) and AUC(Q-infinity) values were higher than that with A. bidentata group, and the C(max) values of chlorogenic acid had significantly difference (P < 0.05), the AUC(0-infinity) values of chlorogenic acid and glycyrrhizin had significantly difference (P < 0.05); The T(max) and CL values of two groups had no significantly difference. Results showed that the established method was specific, rapid, accurate and sensitive for the studies of Tongsaimai pellets four main active ingredients in rat in vivo pharmacokinetic, and A. bidentata have varying degrees of effects on Tongsaimai pellets four main active ingredients in rat in vivo pharmacokinetic behaviors.

  19. Reflector for efficient coupling of a laser beam to air or other fluids

    DOEpatents

    Kare, Jordin T.

    1992-01-01

    A reflector array is disclosed herein that provides a controlled region or regions of plasma breakdowns from a laser beam produced at a remotely-based laser source. The plasma may be applied to produce thrust to propel a spacecraft, or to diagnose a laser beam, or to produce shockwaves. The spacecraft propulsion system comprises a reflector array attached to the vehicle. The reflector array comprises a plurality of reflectors spaced apart on a reflective surface, with each reflector acting as an independent focusing mirror. The reflectors are spaced closely together to form a continuous or partially-continuous surface. The reflector array may be formed from a sheet of reflective material, such as copper or aluminum. In operation, a beam of electromagnetic energy, such as a laser beam, is directed at the reflectors which focus the reflected electromagnetic energy at a plurality of regions off the surface. The energy concentrated in the focal region causes a breakdown of the air or other fluid in the focal region, creating a plasma. Electromagnetic energy is absorbed in the plasma and it grows in volume, compressing and heating the adjacent fluid thereby providing thrust. Laser pulses may be applied repetitively. After each such thrust pulse, fresh air can be introduced next to the surface either laterally, or through a perforated surface. If air or some other gas or vapor is supplied, for example from a tank carried on board a vehicle, this invention may also be used to provide thrust in a vacuum environment.

  20. Theoretical modeling of the dynamics of a semiconductor laser subject to double-reflector optical feedback

    NASA Astrophysics Data System (ADS)

    Bakry, A.; Abdulrhmann, S.; Ahmed, M.

    2016-06-01

    We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.

  1. Simulation of Locking Space Truss Deployments for a Large Deployable Sparse Aperture Reflector

    DTIC Science & Technology

    2015-03-01

    solar cells , there exists the potential to increase the signal gain by using a larger antenna reflector aperture. However, the use of large reflectors, or...and Focus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3 Assumptions and Limitations ...69 Initial Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 First Cell Lockout Event

  2. A Theoretical Analysis of the Radar Cross Section of the Biconical Corner Reflector.

    DTIC Science & Technology

    1980-05-01

    of normal incidence on a symmetrical reflector are corrected. Approved for Public Release POSTAL ADDRESS: Chief Superintendent, Electronics Research... CODE : Electronic Research Laboratory 01 34-TR____________________ 10 rIMPRINT (Publishing organisation) I I COMPUTER PROGRAM(S) Defence Research Centre...limitation. 141 DESCRIPTORS: Radar cross section I COSATI CODES a. EIC Thesaurus Biconical corner reflectors Terms Reference targets b. Non-Thesaurus

  3. Shaped reflector antenna analysis using the Jacobi-Bessel series. [design for space and satellite communication

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Y.; Galindo-Israel, V.

    1980-01-01

    A vector radiation integral is derived for an offset shaped reflector illuminated by an arbitrarily located and oriented source. A procedure for expressing the integral in terms of a series of the Fourier transforms of an effective aperture distribution is discussed. The Jacobi-Bessel series is used to evaluate the Fourier transforms. Numerical results are presented for different reflector configurations and source locations.

  4. 10 CFR 429.35 - Bare or covered (no reflector) medium base compact fluorescent lamps.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Bare or covered (no reflector) medium base compact....35 Bare or covered (no reflector) medium base compact fluorescent lamps. (a) Sampling plan for selection of units for testing. (1) The requirements of § 429.11 are applicable to bare or covered...

  5. 10 CFR 429.35 - Bare or covered (no reflector) medium base compact fluorescent lamps.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Bare or covered (no reflector) medium base compact....35 Bare or covered (no reflector) medium base compact fluorescent lamps. (a) Sampling plan for selection of units for testing. (1) The requirements of § 429.11 are applicable to bare or covered...

  6. 10 CFR 429.35 - Bare or covered (no reflector) medium base compact fluorescent lamps.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Bare or covered (no reflector) medium base compact....35 Bare or covered (no reflector) medium base compact fluorescent lamps. (a) Sampling plan for selection of units for testing. (1) The requirements of § 429.11 are applicable to bare or covered...

  7. Flexible, angle-independent, structural color reflectors inspired by morpho butterfly wings.

    PubMed

    Chung, Kyungjae; Yu, Sunkyu; Heo, Chul-Joon; Shim, Jae Won; Yang, Seung-Man; Han, Moon Gyu; Lee, Hong-Seok; Jin, Yongwan; Lee, Sang Yoon; Park, Namkyoo; Shin, Jung H

    2012-05-08

    Thin-film color reflectors inspired by Morpho butterflies are fabricated. Using a combination of directional deposition, silica microspheres with a wide size distribution, and a PDMS (polydimethylsiloxane) encasing, a large, flexible reflector is created that actually provides better angle-independent color characteristics than Morpho butterflies and which can even be bent and folded freely without losing its Morpho-mimetic photonic properties.

  8. The effects of stainless steel radial reflector on core reactivity for small modular reactor

    SciTech Connect

    Kang, Jung Kil Hah, Chang Joo; Cho, Sung Ju Seong, Ki Bong

    2016-01-22

    Commercial PWR core is surrounded by a radial reflector, which consists of a baffle and water. Radial reflector is designed to reflect neutron back into the core region to improve the neutron efficiency of the reactor and to protect the reactor vessels from the embrittling effects caused by irradiation during power operation. Reflector also helps to flatten the neutron flux and power distributions in the reactor core. The conceptual nuclear design for boron-free small modular reactor (SMR) under development in Korea requires to have the cycle length of 4∼5 years, rated power of 180 MWth and enrichment less than 5 w/o. The aim of this paper is to analyze the effects of stainless steel radial reflector on the performance of the SMR using UO{sub 2} fuels. Three types of reflectors such as water, water/stainless steel 304 mixture and stainless steel 304 are selected to investigate the effect on core reactivity. Additionally, the thickness of stainless steel and double layer reflector type are also investigated. CASMO-4/SIMULATE-3 code system is used for this analysis. The results of analysis show that single layer stainless steel reflector is the most efficient reflector.

  9. Effect of disc reflectors on radiation impedance of short-backfire antenna

    NASA Astrophysics Data System (ADS)

    Marougi, S. D.

    1982-02-01

    Using near-field analysis, the influence of large and small disc reflectors used in short-backfire antennas on the radiation impedance of a dipole feed element has been investigated. The effect of each reflector is evaluated separately, and the overall change in the radiation impedance of the dipole is predicted.

  10. Reflector for efficient coupling of a laser beam to air or other fluids

    DOEpatents

    Kare, J.T.

    1992-10-06

    A reflector array is disclosed herein that provides a controlled region or regions of plasma breakdowns from a laser beam produced at a remotely-based laser source. The plasma may be applied to produce thrust to propel a spacecraft, or to diagnose a laser beam, or to produce shock waves. The spacecraft propulsion system comprises a reflector array attached to the vehicle. The reflector array comprises a plurality of reflectors spaced apart on a reflective surface, with each reflector acting as an independent focusing mirror. The reflectors are spaced closely together to form a continuous or partially-continuous surface. The reflector array may be formed from a sheet of reflective material, such as copper or aluminum. In operation, a beam of electromagnetic energy, such as a laser beam, is directed at the reflectors which focus the reflected electromagnetic energy at a plurality of regions off the surface. The energy concentrated in the focal region causes a breakdown of the air or other fluid in the focal region, creating a plasma. Electromagnetic energy is absorbed in the plasma and it grows in volume, compressing and heating the adjacent fluid thereby providing thrust. Laser pulses may be applied repetitively. After each such thrust pulse, fresh air can be introduced next to the surface either laterally, or through a perforated surface. If air or some other gas or vapor is supplied, for example from a tank carried on board a vehicle, this invention may also be used to provide thrust in a vacuum environment. 10 figs.

  11. The effects of stainless steel radial reflector on core reactivity for small modular reactor

    NASA Astrophysics Data System (ADS)

    Kang, Jung Kil; Hah, Chang Joo; Cho, Sung Ju; Seong, Ki Bong

    2016-01-01

    Commercial PWR core is surrounded by a radial reflector, which consists of a baffle and water. Radial reflector is designed to reflect neutron back into the core region to improve the neutron efficiency of the reactor and to protect the reactor vessels from the embrittling effects caused by irradiation during power operation. Reflector also helps to flatten the neutron flux and power distributions in the reactor core. The conceptual nuclear design for boron-free small modular reactor (SMR) under development in Korea requires to have the cycle length of 4˜5 years, rated power of 180 MWth and enrichment less than 5 w/o. The aim of this paper is to analyze the effects of stainless steel radial reflector on the performance of the SMR using UO2 fuels. Three types of reflectors such as water, water/stainless steel 304 mixture and stainless steel 304 are selected to investigate the effect on core reactivity. Additionally, the thickness of stainless steel and double layer reflector type are also investigated. CASMO-4/SIMULATE-3 code system is used for this analysis. The results of analysis show that single layer stainless steel reflector is the most efficient reflector.

  12. 49 CFR Appendix C to Part 224 - Guidelines for Electronic Submission of Reflectorization Implementation Compliance Reports

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Guidelines for Electronic Submission of Reflectorization Implementation Compliance Reports C Appendix C to Part 224 Transportation Other Regulations... REFLECTORIZATION OF RAIL FREIGHT ROLLING STOCK Pt. 224, App. C Appendix C to Part 224—Guidelines for...

  13. Weighted SAW reflector gratings for orthogonal frequency coded SAW tags and sensors

    NASA Technical Reports Server (NTRS)

    Puccio, Derek (Inventor); Malocha, Donald (Inventor)

    2011-01-01

    Weighted surface acoustic wave reflector gratings for coding identification tags and sensors to enable unique sensor operation and identification for a multi-sensor environment. In an embodiment, the weighted reflectors are variable while in another embodiment the reflector gratings are apodized. The weighting technique allows the designer to decrease reflectively and allows for more chips to be implemented in a device and, consequently, more coding diversity. As a result, more tags and sensors can be implemented using a given bandwidth when compared with uniform reflectors. Use of weighted reflector gratings with OFC makes various phase shifting schemes possible, such as in-phase and quadrature implementations of coded waveforms resulting in reduced device size and increased coding.

  14. Demonstration of radar reflector detection and ground clutter suppression using airborne weather and mapping radar

    NASA Technical Reports Server (NTRS)

    Anderson, D. J.; Bull, J. S.; Chisholm, J. P.

    1982-01-01

    A navigation system which utilizes minimum ground-based equipment is especially advantageous to helicopters, which can make off-airport landings. Research has been conducted in the use of weather and mapping radar to detect large radar reflectors overland for navigation purposes. As initial studies have not been successful, investigations were conducted regarding a new concept for the detection of ground-based radar reflectors and eliminating ground clutter, using a device called an echo processor (EP). A description is presented of the problems associated with detecting radar reflectors overland, taking into account the EP concept and the results of ground- and flight-test investigations. The echo processor concept was successfully demonstrated in detecting radar reflectors overland in a high-clutter environment. A radar reflector target size of 55 dBsm was found to be adequate for detection in an urban environment.

  15. Positive focal shift of gallium nitride high contrast grating focusing reflectors

    NASA Astrophysics Data System (ADS)

    He, Shumin; Wang, Zhenhai; Liu, Qifa

    2016-09-01

    We design a type of metasurfaces capable of serving as a visible-light focusing reflector based on gallium nitride (GaN) high contrast gratings (HCGs). The wavefront of the reflected light is precisely manipulated by spatial variation of the grating periods along the subwavelength ridge array to achieve light focusing. Different from conventional negative focal shift effect, a positive focal shift is observed in such focusing reflectors. Detailed investigations of the influence of device size on the focusing performance, especially the focal length, are preformed via a finite element method . The results show that all performance parameters are greatly affected by the reflector size. A more concentrated focal point, or a better focusing capability, can be achieved by larger size. With increasing reflector size, the achieved focal length decreases and gradually approaches to the design, thus the corresponding positive focal shift decreases. Our results are helpful for understanding the visible-light control of the planar HCG-based focusing reflectors.

  16. GaN-based high-voltage light-emitting diodes with backside reflector

    NASA Astrophysics Data System (ADS)

    Huamao, Huang; Hong, Wang; Xiaosheng, Huang; Jinyong, Hu

    2014-07-01

    High-voltage light-emitting diodes (HV-LED) withbackside reflector, including Ti3O5/SiO2 distributed Bragg reflector (DBR) or hybrid reflector combining DBR and Al or Ag metal layer, are investigated using Monte Carlo ray tracing method. The hybrid reflector leads to more enhancement of light-extraction efficiency (LEE). Moreover, the LEE can also be improved by redesigning the thicknesses of DBR. HV-LED with four redesigned DBR pairs (4-MDBR), and those with a hybrid reflector combining 4-MDBR and Al metal layer (4-MDBR-Al), are fabricated. Compared to 4-MDBR, the enhancement of light-output power induced by 4-MDBR-Al is 4.6%, which is consistent with the simulated value of 4.9%.

  17. Generation of XS library for the reflector of VVER reactor core using Monte Carlo code Serpent

    NASA Astrophysics Data System (ADS)

    Usheva, K. I.; Kuten, S. A.; Khruschinsky, A. A.; Babichev, L. F.

    2017-01-01

    A physical model of the radial and axial reflector of VVER-1200-like reactor core has been developed. Five types of radial reflector with different material composition exist for the VVER reactor core and 1D and 2D models were developed for all of them. Axial top and bottom reflectors are described by the 1D model. A two-group XS library for diffusion code DYN3D has been generated for all types of reflectors by using Serpent 2 Monte Carlo code. Power distribution in the reactor core calculated in DYN3D is flattened in the core central region to more extent in the 2D model of the radial reflector than in its 1D model.

  18. Effect of Laurus nobilis L. Essential Oil and its Main Components on α-glucosidase and Reactive Oxygen Species Scavenging Activity

    PubMed Central

    Sahin Basak, Serap; Candan, Ferda

    2013-01-01

    The present study was designed to determine the effects of the essential oil of Laurus nobilis L. (Lauraceae) and its three main components on α-glucosidase and reactive oxygen species scavenging activity. The chemical composition of the essential oil from Laurus nobilis L. leaves was analyzed by GC/GC-MS and resulted in the identification of 29 compounds, representing 99.18% of the total oil. 1,8-cineole (68.82%), 1-(S)-α-pinene (6.94%), and R-(+)- limonene (3.04%) were determined to be the main components. The antioxidant features of the essential oil and its three main components were evaluated using inhibition of 2,2-diphenyl-1- picrylhydrazyl, hydroxyl, and superoxide radicals, inhibition of hydrogen peroxide and lipid peroxidation assays. The results show that the DPPH, hydroxyl, and superoxide radical as well as hydrogen peroxide scavenging activities of the essential oil are greater than the positive controls and the three main components of the oil when tested independently. The inhibition of lipid peroxidation by the oil occurred less frequently than with 1,8-cineole and R-(+)- limonene alone, but the effects were more pronounced than those seen with 1-(S)-α-pinene and the positive controls. An α-glucosidase inhibition assay was applied to evaluate the in-vitro antidiabetic activity of the essential oil. IC50-values were obtained for laurel essential oil, 1, 8-cineole, 1-(S)-α-pinene, and R-(+)-limonene: 1.748 μL/mL, 1.118 μL/mL, 1.420 μL/mL and 1.300 μL/mL, respectively. We also found that laurel essential oil and 1, 8-cineole inhibited the α-glucosidase competitively while 1-(S)-α-pinene and R-(+)-limonene were uncompetitive inhibitors. PMID:24250611

  19. The Effects of Xiangqing Anodyne Spray on Treating Acute Soft-Tissue Injury Mainly Depend on Suppressing Activations of AKT and p38 Pathways

    PubMed Central

    Wang, Shudong; Li, Tao; Qu, Wei; Li, Xin; Ma, Shaoxin; Wang, Zheng; Liu, Wenya; Hou, Shanshan; Fu, Jihua

    2016-01-01

    Objectives. In the present study we try to elucidate the mechanism of Xiangqing anodyne spray (XQAS) effects on acute soft-tissue injury (STI). Methods. Acute STI model was established by hammer blow in the rat hind leg muscle. Within 8 hours, instantly after modeling and per 2-hour interval repeated topical applications with or without XQAS, CP or IH ethanol extracts spray (CPS and IHS) were performed, respectively; muscle swelling rate and inflammation-related biochemical parameters, muscle histological observation, and mRNA and protein expression were then examined. Results. XQAS dose-dependently suppressed STI-caused muscle swelling, proinflammatory mediator productions, and oxidative stress as well as severe pathological changes in the injured muscle tissue. Moreover, CPS mainly by blocking p38 activation while IHS majorly by blocking AKT activation led to cytoplastic IκBα degradation with NF-κB p65 translocated into the nucleus. There are synergistic effects between CP and IH components in the XQAS on preventing from acute STI with suppressing IκBα degradation, NF-κB p65 translocation, and subsequent inflammation and oxidative stress-related abnormality. Conclusion. Marked effects of XQAS on treating acute STI are ascribed to strong anti-inflammatory and antioxidative actions with a reasonable combination of CP active components, blocking p38-NF-κB pathway activated, and IH active components, blocking AKT-NF-κB pathway activated. PMID:27190541

  20. Peroxisome Proliferator-Activated Receptor α Activation Is Not the Main Contributor to Teratogenesis Elicited by Polar Compounds from Oxidized Frying Oil.

    PubMed

    Lin, Yu-Shun; Lin, Ting-Yi; Wu, Jia-Jiuan; Yao, Hsien-Tsung; Chang, Sunny Li-Yun; Chao, Pei-Min

    2017-02-27

    We previously reported that polar compounds (PO) in cooking oil are teratogenic and perturbed retinoic acid (RA) metabolism. Considering PO as a potent peroxisome proliferator-activated receptor α (PPARα) activator, this study aimed to investigate the role of PPARα in PO-induced teratogenesis and disturbance of RA metabolism. Female PPARα knockout or wild type mice were mated with males of the same genotype. Pregnant mice were fed a diet containing 10% fat from either fresh oil (FO) or PO from gestational day1 to day18, and killed at day18. The PO diet significantly increased the incidence of teratogenesis and fetal RA concentrations, regardless of genotype. Though PPARα deficiency disturbed maternal RA homeostasis, itself did not contribute to teratogenesis as long as FO diet was given. The mRNA profile of genes involved in RA metabolism was differentially affected by diet or genotype in mothers and fetuses. Based on hepatic mRNA levels of genes involved in xenobiotic metabolism, we inferred that PO not only activated PPARα, but also altered transactivity of other xenobiotic receptors. We concluded that PO-induced fetal anomalies and RA accumulation were independent of PPARα activation.