Ultra-Wideband Array in PCB for Millimeter-Wave 5G and ISM

NASA Technical Reports Server (NTRS)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2017-01-01

Growing mobile data consumption has prompted the exploration of the millimeter-wave spectrum for large bandwidth, high speed communications. However, the allocated bands are spread across a wide swath of spectrum: Fifth generation mobile architecture (5G): 28, 38, 39, 6471 GHz; Industrial, Scientific, and Medical bands (ISM): 24, 60 GHz. Moreover, high gain phased arrays are required to overcome the significant path loss associated with these frequencies. Further, it is necessary to incorporate several of these applications in a single, small size and low cost platform. To this end, we have developed a scanning, Ultra-Wideband (UWB) array which covers all 5G, ISM, and other mm-W bands from 2472 GHz. Critically, this is accomplished using mass-production Printed Circuit Board (PCB) fabrication. The results of this work are presented in this poster.

Millimeter wavelength observations of solar flares for Max 1991

NASA Technical Reports Server (NTRS)

Kundu, M. R.; Gopalswamy, N.; Nitta, N.; Schmahl, E. J.; White, S. M.; Welch, W. J.

1988-01-01

The Hat Creek millimeter-wave interferometer (to be known as the Berkeley-Illinois-Maryland Array, BIMA) is being upgraded. The improved array will become available during the coming solar maximum, and will have guaranteed time for solar observing. The Hat Creek millimeter-wave interferometer is described along with the improvements. The scientific objectives are briefly discussed.

The Atacama Large Millimeter Array (ALMA)

NASA Astrophysics Data System (ADS)

1999-06-01

The Atacama Large Millimeter Array (ALMA) is the new name [2] for a giant millimeter-wavelength telescope project. As described in the accompanying joint press release by ESO and the U.S. National Science Foundation , the present design and development phase is now a Europe-U.S. collaboration, and may soon include Japan. ALMA may become the largest ground-based astronomy project of the next decade after VLT/VLTI, and one of the major new facilities for world astronomy. ALMA will make it possible to study the origins of galaxies, stars and planets. As presently envisaged, ALMA will be comprised of up to 64 12-meter diameter antennas distributed over an area 10 km across. ESO PR Photo 24a/99 shows an artist's concept of a portion of the array in a compact configuration. ESO PR Video Clip 03/99 illustrates how all the antennas will move in unison to point to a single astronomical object and follow it as it traverses the sky. In this way the combined telescope will produce astronomical images of great sharpness and sensitivity [3]. An exceptional site For such observations to be possible the atmosphere above the telescope must be transparent at millimeter and submillimeter wavelengths. This requires a site that is high and dry, and a high plateau in the Atacama desert of Chile, probably the world's driest, is ideal - the next best thing to outer space for these observations. ESO PR Photo 24b/99 shows the location of the chosen site at Chajnantor, at 5000 meters altitude and 60 kilometers east of the village of San Pedro de Atacama, as seen from the Space Shuttle during a servicing mission of the Hubble Space Telescope. ESO PR Photo 24c/99 and ESO PR Photo 24d/99 show a satellite image of the immediate vicinity and the site marked on a map of northern Chile. ALMA will be the highest continuously operated observatory in the world. The stark nature of this extreme site is well illustrated by the panoramic view in ESO PR Photo 24e/99. High sensitivity and sharp images ALMA

The Atacama Large Millimeter/submillimeter Array - from Early Science to Full Operations.

NASA Astrophysics Data System (ADS)

Remijan, Anthony

2017-06-01

The Atacama Large Millimeter/Submillimeter Array (ALMA) is now entering its 6th cycle of scientific observations. Starting with Cycle 3, science observations were no longer considered "Early Science" or "best efforts". Cycle 5 is now the third cycle of "steady state" observations and Cycle 7 is advertised to begin ALMA "full science" operations. ALMA Full Science Operations will include all the capabilities that were agreed upon by the international consortium after the ALMA re-baselining effort. In this talk, I will detail the upcoming ALMA Cycle 5 observing capabilities, describe the process of selecting new observing modes for upcoming cycles and provide an update on the status of the ALMA Full Science capabilities.

Synthesis of Millimeter-Scale Carbon Nanotube Arrays and Their Applications on Electrochemical Supercapacitors

NASA Astrophysics Data System (ADS)

Cui, Xinwei

This research is aimed at synthesizing millimeter-scale carbon nanotube arrays (CNTA) by conventional chemical vapor deposition (CCVD) and water-assisted chemical vapor deposition (WACVD) methods, and exploring their application as catalyst supports for electrochemical supercapacitors. The growth mechanism and growth kinetics of CNTA under different conditions were systematically investigated to understand the relationship among physical characteristics of catalyst particles, growth parameters, and carbon nanotube (CNT) structures within CNTAs. Multiwalled CNT (MWCNT) array growth demonstrates lengthening and thickening stages in CCVD and WACVD. In CCVD, the lengthening and thickening were found to be competitive. By investigating catalyst particles after different pretreatment conditions, it has been found that inter-particle spacing plays a significant role in influencing CNTA height, CNT diameter and wall number. In WACVD, a long linear lengthening stage has been found. CNT wall number remains constant and catalysts preserve the activity in this stage, while MWCNTs thicken substantially and catalysts deactivate following the previously proposed radioactive decay model in the thickening stage of WACVD. Water was also shown to preserve the catalyst activity by significantly inhibiting catalyst-induced and gas phase-induced thickening processes in WACVD. Mn3O4 nanoparticles were successfully deposited and uniformly distributed within millimeter-long CNTAs by dip-casting method from non-aqueous solutions. After modification with Mn3O4 nanoparticles, CNTAs have been changed from hydrophobic to hydrophilic without their alignment and integrity being destroyed. The hydrophilic Mn 3O4/CNTA composite electrodes present ideal capacitive behavior with high reversibility. This opens up a new route of utilizing ultra-long CNTAs, based on which a scalable and cost-effective method was developed to fabricate composite electrodes using millimeter-long CNTAs. To improve the

Expanded Owens Valley Solar Array (EOVSA) Testbed and Prototype

NASA Astrophysics Data System (ADS)

Gary, Dale E.; Nita, G. M.; Sane, N.

2012-05-01

NJIT is engaged in constructing a new solar-dedicated radio array, the Expanded Owens Valley Solar Array (EOVSA), which is slated for completion in late 2013. An initial 3-antenna array, the EOVSA Subsystem Testbed (EST), is now in operation from 1-9 GHz based on three of the old OVSA antennas, to test certain design elements of the new array. We describe this instrument and show some results from recent solar flares observed with it. We also describe plans for an upcoming prototype of EOVSA, which will use three antennas of the new design over the full 1-18 GHz signal chain of the entirely new system. The EOVSA prototype will be in operation by late 2012. Highlights of the new design are ability to cover the entire 1-18 GHz in less than 1 s, simultaneous dual polarization, and improved sensitivity and stability. We discuss what can be expected from the prototype, and how it will compare with the full 13-antenna EOVSA. This work was supported by NSF grants AGS-0961867 and AST-0908344, and NASA grant NNX11AB49G to New Jersey Institute of Technology.

Millimeter-wave pseudomorphic HEMT MMIC phased array components for space communications

NASA Technical Reports Server (NTRS)

Lan, G. L.; Pao, C. K.; Wu, C. S.; Mandolia, G.; Hu, M.; Yuan, S.; Leonard, Regis

1991-01-01

Recent advances in pseudomorphic HEMT MMIC (PMHEMT/MMIC) technology have made it the preferred candidate for high performance millimeter-wave components for phased array applications. This paper describes the development of PMHEMT/MMIC components at Ka-band and V-band. Specifically, the following PMHEMT/MMIC components will be described: power amplifiers at Ka-band; power amplifiers at V-band; and four-bit phase shifters at V-band. For the Ka-band amplifier, 125 mW output power with 5.5 dB gain and 21 percent power added efficiency at 2 dB compression point has been achieved. For the V-band amplifier, 112 mW output power with 6 dB gain and 26 percent power added efficiency has been achieved. And, for the V-band phase shifter, four-bit (45 deg steps) phase shifters with less than 8 dB insertion loss from 61 GHz to 63 GHz will be described.

Dexterous ultrasonic levitation of millimeter-sized objects in air.

PubMed

Seah, Sue Ann; Drinkwater, Bruce W; Carter, Tom; Malkin, Rob; Subramanian, Sriram

2014-07-01

Acoustic levitation in air has applications in contactless handling and processing. Here a first-order Bessel function-shaped acoustic field, generated using an 8-element circular array operating at 40 kHz, traps millimeter-sized objects against gravity. The device can manipulate objects in a vertical plane over a few millimeters with an accuracy of ± 0.09 mm.

The Expanded Owens Valley Solar Array

NASA Astrophysics Data System (ADS)

Gary, Dale E.; Hurford, G. J.; Nita, G. M.; White, S. M.; Tun, S. D.; Fleishman, G. D.; McTiernan, J. M.

2011-05-01

The Expanded Owens Valley Solar Array (EOVSA) is now under construction near Big Pine, CA as a solar-dedicated microwave imaging array operating in the frequency range 1-18 GHz. The solar science to be addressed focuses on the 3D structure of the solar corona (magnetic field, temperature and density), on the sudden release of energy and subsequent particle acceleration, transport and heating, and on space weather phenomena. The project will support the scientific community by providing open data access and software tools for analysis of the data, to exploit synergies with on-going solar research in other wavelengths. The New Jersey Institute of Technology (NJIT) is expanding OVSA from its previous complement of 7 antennas to a total of 15 by adding 8 new antennas, and will reinvest in the existing infrastructure by replacing the existing control systems, signal transmission, and signal processing with modern, far more capable and reliable systems based on new technology developed for the Frequency Agile Solar Radiotelescope (FASR). The project will be completed in time to provide solar-dedicated observations during the upcoming solar maximum in 2013 and beyond. We provide an update on current status and our preparations for exploiting the data through modeling and data analysis tools. This research is supported by NSF grants AST-0908344, and AGS-0961867 and NASA grant NNX10AF27G to New Jersey Institute of Technology.

Millimeter and Sub-millimeter High Resolution Spectroscopy: New Frontiers with ALMA

NASA Astrophysics Data System (ADS)

Ziurys, Lucy M.

2016-06-01

It is becoming increasingly clear that new laboratory data will be critical for the next decade of observations with the Atacama Large Millimeter Array (ALMA). The high spatial resolution offered by ALMA will probe new regions of molecular complexity, including the inner envelopes of evolved stars, regions dominated by UV radiation, and the densest cores of molecular clouds. New molecular lines will be discovered in the wide wavelength range covered by the ALMA bands, and high resolution, gas-phase spectroscopy are needed to provide crucial “rest frequencies.” In particular, highly accurate methods that measure millimeter and sub-millimeter rotational transitions, such as direct absorption and Fourier transform mm-wave techniques, are important, especially when coupled to exotic molecular production schemes. Recent ALMA studies of SH+ and larger organic species have already demonstrated the need for laboratory measurements. New laboratory work will likely be required for circumstellar refractory molecules, radicals and ions generated near photon-dominated regions (PDRs), and large, organic-type species. This talk will give an overview of current contributions of laboratory spectroscopy to ALMA observations, summarize relevant spectroscopic techniques, and provide input into future prospects and directions.

Science with the Expanded Owens Valley Solar Array

NASA Astrophysics Data System (ADS)

Nita, Gelu M.; Gary, Dale E.; Fleishman, Gregory D.; Chen, Bin; White, Stephen M.; Hurford, Gordon J.; McTiernan, James; Hickish, Jack; Yu, Sijie; Nelin, Kjell B.

2017-08-01

The Expanded Owens Valley Solar Array (EOVSA) is a solar-dedicated radio array that makes images and spectra of the full Sun on a daily basis. Our main science goals are to understand the basic physics of solar activity, such as how the Sun releases stored magnetic energy on timescales of seconds, and how that solar activity, in the form of solar flares and coronal mass ejections, influences the Earth and near-Earth space environment, through disruptions of communication and navigation systems, and effects on satellites and systems on the ground. The array, which is composed out of thirteen 2.1 m dishes and two 27 m dishes (used only for calibration), has a footprint of 1.1 km EW x 1.2 km NS and it is capable of producing, every second, microwave images at two polarizations and 500 science channels spanning the 1-18 GHz frequency range. Such ability to make multi-frequency images of the Sun in this broad range of frequencies, with a frequency dependent resolution ranging from ˜53” at 1 GHz to ˜3”at 18 GHz, is unique in the world. Here we present an overview of the EOVSA instrument and a first set of science-quality active region and solar flare images produced from data taken during April 2017.This research is supported by NSF grant AST-1615807 and NASA grant NNX14AK66G to New Jersey Institute of Technology.

System engineering of the Atacama Large Millimeter/submillimeter Array

NASA Astrophysics Data System (ADS)

Bhatia, Ravinder; Marti, Javier; Sugimoto, Masahiro; Sramek, Richard; Miccolis, Maurizio; Morita, Koh-Ichiro; Arancibia, Demián.; Araya, Andrea; Asayama, Shin'ichiro; Barkats, Denis; Brito, Rodrigo; Brundage, William; Grammer, Wes; Haupt, Christoph; Kurlandczyk, Herve; Mizuno, Norikazu; Napier, Peter; Pizarro, Eduardo; Saini, Kamaljeet; Stahlman, Gretchen; Verzichelli, Gianluca; Whyborn, Nick; Yagoubov, Pavel

2012-09-01

The Atacama Large Millimeter/submillimeter Array (ALMA) will be composed of 66 high precision antennae located at 5000 meters altitude in northern Chile. This paper will present the methodology, tools and processes adopted to system engineer a project of high technical complexity, by system engineering teams that are remotely located and from different cultures, and in accordance with a demanding schedule and within tight financial constraints. The technical and organizational complexity of ALMA requires a disciplined approach to the definition, implementation and verification of the ALMA requirements. During the development phase, System Engineering chairs all technical reviews and facilitates the resolution of technical conflicts. We have developed analysis tools to analyze the system performance, incorporating key parameters that contribute to the ultimate performance, and are modeled using best estimates and/or measured values obtained during test campaigns. Strict tracking and control of the technical budgets ensures that the different parts of the system can operate together as a whole within ALMA boundary conditions. System Engineering is responsible for acceptances of the thousands of hardware items delivered to Chile, and also supports the software acceptance process. In addition, System Engineering leads the troubleshooting efforts during testing phases of the construction project. Finally, the team is conducting System level verification and diagnostics activities to assess the overall performance of the observatory. This paper will also share lessons learned from these system engineering and verification approaches.

MESAS: Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter Wavelengths

NASA Astrophysics Data System (ADS)

White, Jacob Aaron; Aufdenberg, Jason; Boley, A. C.; Hauschildt, Peter; Hughes, Meredith; Matthews, Brenda; Wilner, David

2018-06-01

In the early stages of planet formation, small dust grains grow to become millimeter-sized particles in debris disks around stars. These disks can in principle be characterized by their emission at submillimeter and millimeter wavelengths. Determining both the occurrence and abundance of debris in unresolved circumstellar disks of A-type main-sequence stars requires that the stellar photospheric emission be accurately modeled. To better constrain the photospheric emission for such systems, we present observations of Sirius A, an A-type star with no known debris, from the James Clerk Maxwell Telescope, Submillimeter Array, and Jansky Very Large Array at 0.45, 0.85, 0.88, 1.3, 6.7, and 9.0 mm. We use these observations to inform a PHOENIX model of Sirius A’s atmosphere. We find the model provides a good match to these data and can be used as a template for the submillimeter/millimeter emission of other early A-type stars where unresolved debris may be present. The observations are part of an ongoing observational campaign entitled Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths.

Wide-Field-of-View Millimeter-Wave Telescope Design with Ultra-Low Cross-Polarization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernacki, Bruce E.; Kelly, James F.; Sheen, David M.

2012-05-01

As millimeter-wave arrays become available, off-axis imaging performance of the fore optics increases in importance due to the relatively large physical extent of the arrays. Typically, simple optical telescope designs are adapted to millimeter-wave imaging but single-mirror spherical or classic conic designs cannot deliver adequate image quality except near the optical axis. Since most millimeter-wave designs are quasi-optical, optical ray tracing and commercial design software can be used to optimize designs to improve off-axis imaging as well as minimize cross-polarization. Methods that obey the Dragone-Mizuguchi condition for the design of reflective millimeter-wave telescopes with low cross-polarization also provide additional degreesmore » of freedom that offer larger fields of view than possible with single-reflector designs. Dragone’s graphical design method does not lend itself readily to computer-based optical design approaches, but subsequent authors expanded on Dragone’s geometric design approach with analytic expressions that describe the location, shape, off-axis height and tilt of the telescope elements that satisfy Dragone’s design rules and can be used as a first-order design for subsequent computer-based design and optimization. We investigate two design variants that obey the Dragone-Mizuguchi conditions that exhibit ultra-low polarization crosstalk and a large diffraction-limited field of view well suited to millimeter-wave imaging arrays.« less

Wide-field-of-view millimeter-wave telescope design with ultra-low cross-polarization

NASA Astrophysics Data System (ADS)

Bernacki, Bruce E.; Kelly, James F.; Sheen, David; Hatchell, Brian; Valdez, Patrick; Tedeschi, Jonathan; Hall, Thomas; McMakin, Douglas

2012-06-01

As millimeter-wave arrays become available, off-axis imaging performance of the fore optics increases in importance due to the relatively large physical extent of the arrays. Typically, simple optical telescope designs are adapted to millimeter-wave imaging but single-mirror spherical or classic conic designs cannot deliver adequate image quality except near the optical axis. Since millimeter-wave designs are quasi-optical, optical ray tracing and commercial design software can be used to optimize designs to improve off-axis imaging as well as minimize cross-polarization. Methods that obey the Dragone-Mizuguchi condition for the design of reflective millimeter-wave telescopes with low cross-polarization also provide additional degrees of freedom that offer larger fields of view than possible with single-reflector designs. Dragone's graphical design method does not lend itself readily to computer-based optical design approaches, but subsequent authors expanded on Dragone's geometric design approach with analytic expressions that describe the location, shape, off-axis height and tilt of the telescope elements that satisfy Dragone's design rules and can be used as a first-order design for subsequent computer-based design and optimization. We investigate two design variants that obey the Dragone-Mizuguchi conditions that exhibit ultra-low cross-polarization and a large diffraction-limited field of view well suited to millimeter-wave imaging arrays.

Microwave/millimeter wave technology

NASA Astrophysics Data System (ADS)

Abita, Joseph L.

1988-09-01

The microwave/millimeter-wave monolithic integrated-circuit (MIMIC) technology and systems are discussed along with the application of MIMICs in electronic warfare. The components of a MIMIC are described, with particular attention given to the active-array antenna transmit/receive module, which is at the focus of the MIMIC, and to the features of a typical MIMIC chip. The typical performance characteristics of MIMIC components are presented in tabular form.

Heterodyne Arrays for Terahertz/Sub-millimeter Astronomy

NASA Astrophysics Data System (ADS)

Kloosterman, Jenna; Walker, C. K.; SORAL; SRON; TU-Delft; JPL; APL; ASU; MIT

2014-01-01

The clouds of gas and dust that constitute the Interstellar Medium (ISM) within the Milky Way and other galaxies can be studied through the emission from atoms and molecules such as CO, [CI], [CII], [NII], and [OI]. Spectroscopic surveys of these tracers are necessary to disentangle large-scale structure and kinematics within the ISM. Each of these tracers has transitions in the Terahertz (THz) region of the electromagnetic spectrum, loosely defined as 0.3 - 3 THz, thus creating a need for large format THz heterodyne arrays. My dissertation research in radio instrumentation has focused on three main projects. The first, the Superheterodyne Camera (SuperCam), is a ground-based instrument for the Sub-millimeter Telescope (SMT) on Mt. Graham, Arizona. The receiver contains 64 heterodyne pixels designed to detect the J=3-2 rotational line of CO at 345 GHz. SuperCam had its first engineering run in Spring 2012 and its commissioning run in Spring 2013. The second project, the Stratospheric Terahertz Observatory (STO), is a balloon-borne, 0.8 m telescope, designed to observe the fine structure lines of [NII] and [CII] at 1.46 and 1.9 THz from an altitude of ~120,000 ft. STO had its first flight around Antarctica in January 2012 and is scheduled to have a second flight (as STO-2) in 2015. The last project is the building of a 4.74 THz heterodyne receiver to look for the fine structure line of the high density tracer [OI]. With an 815 K double sideband noise temperature (e.g. ~7 times the quantum noise limit), this is the most sensitive heterodyne receiver reported above 3 THz. It will be flown on STO-2 and was developed as part of the Galactic/extra-galactic Ultra-Long Duration Stratospheric Spectroscopic THz Observatory (GUSSTO) concept study. This dissertation talk will briefly cover the results of these instrumentation efforts and the science that drives them.

A Virtual Sky with Extragalactic H I and CO Lines for the Square Kilometre Array and the Atacama Large Millimeter/Submillimeter Array

NASA Astrophysics Data System (ADS)

Obreschkow, D.; Klöckner, H.-R.; Heywood, I.; Levrier, F.; Rawlings, S.

2009-10-01

We present a sky simulation of the atomic H I-emission line and the first 10 12C16O rotational emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500 h -1 Mpc; hence, the actual field of view depends on the (user-defined) maximal redshift z max; e.g., for z max = 10, the field of view yields ~4 × 4 deg2. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the H I and CO-emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 108 M sun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Λ cold dark matter (ΛCDM) cosmology. The evolving CDM distribution was adopted from the Millennium Simulation, an N-body CDM simulation in a cubic box with a side length of 500 h -1 Mpc. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such as the Square Kilometre Array, Large Millimeter Telescope, and Atacama Large Millimeter/Submillimeter Array. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz analyses for peak flux density limited and total flux limited surveys of H I and CO. A key prediction is that H I will be harder to detect at redshifts z gsim 2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models. -SAX-Sky"

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

NASA Astrophysics Data System (ADS)

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B.; Tai, Yuan-Chuan

2010-05-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 × 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 × 0.8 × 3 mm3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 × 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array.

PubMed

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

2010-05-07

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm(3) and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and +/-5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when +/-10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

PubMed Central

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

2010-01-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 × 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 × 0.8 × 3 mm3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 × 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

Limits on Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array

NASA Technical Reports Server (NTRS)

Holzapfel, W. L.; Carlstrom, J. E.; Grego, L.; Holder, G. P.; Joy, M. K.; Reese, E. D.; Rose, M. Franklin (Technical Monitor)

2000-01-01

We have used the Berkeley-Illinois-Maryland-Association (BIMA) millimeter array outfitted with sensitive cm-wave receivers to search for Cosmic Microwave Background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration which produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is 6.6 arcminutes. We have made sensitive images of seven fields, five of which where chosen specifically to have low IR dust contrast and be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power Q_flat = 5.6 (+3.0, -5.6) uK and Q_flat < 14.1 uK at 68% and 95% confidence. The sensitivity of this experiment to flat band power peaks at a multipole of l = 5470, which corresponds to an angular scale of approximately 2 arcminutes The most likely value of Q_flat is similar to the level of the expected secondary anisotropies.

Probing Titan's Complex Atmospheric Chemistry Using the Atacama Large Millimeter/Submillimeter Array

NASA Technical Reports Server (NTRS)

Cordiner, Martin A.; Nixon, Conor; Charnley, Steven B.; Teanby, Nick; Irwin, Pat; Serigano, Joseph; Palmer, Maureen; Kisiel, Zbigniew

2015-01-01

Titan is Saturn's largest moon, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Atmospheric photochemistry results in the production of a wide range of complex organic molecules, including hydrocarbons, nitriles, aromatics and other species of possible pre-biotic relevance. Titan's carbon-rich atmosphere may be analogous to that of primitive terrestrial planets throughout the universe, yet its origin, evolution and complete chemical inventory are not well understood. Here we present spatially-resolved maps of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH in Titan's atmosphere, observed using the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012-2013. These data show previously-undetected spatial structures for the observed species and provide the first spectroscopic detection of C2H5CN on Titan. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with photochemical production and transport in the upper atmosphere followed by subsidence over the poles. The HNC emission peaks are offset from the polar axis, indicating that Titan's mesosphere may be more longitudinally variable than previously thought.

High-altitude medical and operations problems and solutions for the Millimeter Array

NASA Astrophysics Data System (ADS)

Napier, Peter J.; West, John B.

1998-07-01

The 5000m altitude of the potential site for the Millimeter Array (MMA) in Northern Chile is so high that high-altitude problems for both the staff and equipment must be considered and included in planing for the facility. The very good accessibility of the site, only one hour's drive from the nearest town at altitude 2440m, makes it possible for MMA workers to sleep and perform much of their work at low altitude. Workers on the site will have 11 percent less oxygen available than workers at Mauna Kea Observatory. It is expected that the mental abilities and ability to do hard physical labor of workers on the high site will be reduced by 10 percent to 30 percent compared to sea-level. In-doors working areas on the MMA site will have their atmospheres oxygen enriched to provide an effective working altitude of 3500m where loss of mental ability should be small. Tests of oxygen enrichment at high-altitude Chilean mines and at the University of California White Mountain Research Station show that it is feasible and economic. Problems of equipment operation at 5000m altitude are expected to be manageable.

Millimeter-Wave Polarimeters Using Kinetic Inductance Detectors for TolTEC and Beyond

NASA Astrophysics Data System (ADS)

Austermann, J. E.; Beall, J. A.; Bryan, S. A.; Dober, B.; Gao, J.; Hilton, G.; Hubmayr, J.; Mauskopf, P.; McKenney, C. M.; Simon, S. M.; Ullom, J. N.; Vissers, M. R.; Wilson, G. W.

2018-05-01

Microwave kinetic inductance detectors (MKIDs) provide a compelling path forward to the large-format polarimeter, imaging, and spectrometer arrays needed for next-generation experiments in millimeter-wave cosmology and astronomy. We describe the development of feedhorn-coupled MKID detectors for the TolTEC millimeter-wave imaging polarimeter being constructed for the 50-m Large Millimeter Telescope (LMT). Observations with TolTEC are planned to begin in early 2019. TolTEC will comprise ˜ 7000 polarization-sensitive MKIDs and will represent the first MKID arrays fabricated and deployed on monolithic 150 mm diameter silicon wafers—a critical step toward future large-scale experiments with over 10^5 detectors. TolTEC will operate in observational bands at 1.1, 1.4, and 2.0 mm and will use dichroic filters to define a physically independent focal plane for each passband, thus allowing the polarimeters to use simple, direct-absorption inductive structures that are impedance matched to incident radiation. This work is part of a larger program at NIST-Boulder to develop MKID-based detector technologies for use over a wide range of photon energies spanning millimeter-waves to X-rays. We present the detailed pixel layout and describe the methods, tools, and flexible design parameters that allow this solution to be optimized for use anywhere in the millimeter and sub-millimeter bands. We also present measurements of prototype devices operating in the 1.1 mm band and compare the observed optical performance to that predicted from models and simulations.

Highly Efficient Broadband Multiplexed Millimeter-Wave Vortices from Metasurface-Enabled Transmit-Arrays of Subwavelength Thickness

NASA Astrophysics Data System (ADS)

Jiang, Zhi Hao; Kang, Lei; Hong, Wei; Werner, Douglas H.

2018-06-01

Structured electromagnetic waves carrying nonvanishing orbital angular momentum (OAM) have recently opened up alternative frontiers in the field of wave physics, holding great promise for a wide range of potential applications. By leveraging geometric phases originating from spin-to-orbital interactions, spin-dependent wave phenomena can be created, leading to a more versatile realm of dispersionless wave-front manipulation. However, the currently available transmissive vortex-beam generators suffer from a narrow bandwidth, require an optically thick device profile, or are limited by a low efficiency, severely restricting their integration into systems and/or widespread usage for practical applications. We present the design methodology and a physical analysis and complete experimental characterization of a class of millimeter-wave Pancharatnam-Berry transmit-arrays with a thickness of about λ0/3 , which enables highly efficient generation and separation of spin-controlled vortex beams over a broad bandwidth, achieving an unprecedented peak efficiency of 88% for a single vortex beam and 71% for dual vortex beams. The proposed transmit-array, which is capable of providing two-dimensional OAM multiplexing and demultiplexing without normal-mode background interference, overcomes all previous roadblocks and paves the way for high-efficiency electromagnetic vortex-beam generation as well as other wave-front-shaping devices from microwave frequencies to optical wavelengths.

24-71 GHz PCB Array for 5G ISM

NASA Technical Reports Server (NTRS)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2017-01-01

Millimeter-wave 5G mobile architectures need to consolidate disparate frequency bands into a single, multifunctional array. Existing arrays are either narrow-band, prohibitively expensive or cannot be scaled to these frequencies. In this paper, we present the first ultra-wideband millimeter wave array to operate across six 5G and ISM bands spanning 24-71 GHz. Importantly, the array is realized using low-cost PCB. The paper presents the design and optimized layout, and discusses fabrication and measurements.

Astronomers Break Ground on Atacama Large Millimeter Array (ALMA) - World's Largest Millimeter Wavelength Telescope

NASA Astrophysics Data System (ADS)

2003-11-01

Scientists and dignitaries from Europe, North America and Chile are breaking ground today (Thursday, November 6, 2003) on what will be the world's largest, most sensitive radio telescope operating at millimeter wavelengths . ALMA - the "Atacama Large Millimeter Array" - will be a single instrument composed of 64 high-precision antennas located in the II Region of Chile, in the District of San Pedro de Atacama, at the Chajnantor altiplano, 5,000 metres above sea level. ALMA 's primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimetre portion of the electromagnetic spectrum. The Atacama Large Millimeter Array (ALMA) is an international astronomy facility. ALMA is an equal partnership between Europe and North America, in cooperation with the Republic of Chile, and is funded in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC), and in Europe by the European Southern Observatory (ESO) and Spain. ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI), and on behalf of Europe by ESO. " ALMA will be a giant leap forward for our studies of this relatively little explored spectral window towards the Universe" , said Dr. Catherine Cesarsky , Director General of ESO. "With ESO leading the European part of this ambitious and forward-looking project, the impact of ALMA will be felt in wide circles on our continent. Together with our partners in North America and Chile, we are all looking forward to the truly outstanding opportunities that will be offered by ALMA , also to young scientists and engineers" . " The U.S. National Science Foundation joins today with our North American partner, Canada, and with the European Southern Observatory, Spain, and Chile to prepare

Spatially Resolved Sub-millimeter Continuum Imaging of Neptune with ALMA

NASA Astrophysics Data System (ADS)

Iino, Takahiro; Yamada, Takayoshi

2018-02-01

This paper reports the result of spatially resolved 646 GHz sub-millimeter imaging observation of Neptune obtained by the Atacama Large Millimeter and sub-millimeter Array. The observation was performed in 2012 August as the flux calibration and synthesized beam size were small enough to resolve Neptune’s disk at this time. This analysis aims to constrain the vertical structure of deep and upper-tropospheric South polar hot spot detected previously with mid-IR, millimeter, and centimeter wavelength. The probed atmospheric pressure region estimated by the radiative-transfer method was between 1.0 and 0.6 bar for the nadir and South pole views, respectively. The South polar hot spot was not detected clearly with an uncertainty of 2.1 K. The apparent discontinuity of tropospheric and stratospheric hot spot may be caused by the vertical wind shear of South polar zonal jet.

Integrated Millimeter-Wave Frequency Multiplers

NASA Astrophysics Data System (ADS)

Schoenthal, Gerhard S.; Deaver, B. S.; Crowe, T. W.; Bishop, W. L.; Saini, K.; Bradley, R. F.

2001-11-01

Many of the molecules of interest to radio astronomers and atmospheric chemists resonate at frequencies in the millimeter and submillimeter wavelength bands. To measure the spectra of these molecules scientists rely on heterodyne receivers that convert the high frequency signal to the GHz band where it is readily amplified and analyzed. One of the challenges of developing suitable receiver systems is the development of compact, reliable and affordable sources of local oscillator power at frequencies in excess of 100 GHz. One useful solution is to use GaAs Schottky diodes, in their varactor mode, to generate high frequency harmonics of lower frequency sources such as Gunn oscillators. As a part of a multi-national radio astronomy project, the Atacama Millimeter Large Array (ALMA), we have designed and fabricated a broadband frequency tripler with an output centered at 240 GHz. It is integrated on a quartz substrate to greatly reduce the parasitic capacitance and thereby improve electrical performance. The integrated circuit was designed to require no oxides or ohmic contacts, thereby easing fabrication. This talk will discuss the novel millimeter-wave integrated circuit fabrication process and the initial results.

Millimeter and submillimeter wave spectroscopy of propanal

NASA Astrophysics Data System (ADS)

Zingsheim, Oliver; Müller, Holger S. P.; Lewen, Frank; Jørgensen, Jes K.; Schlemmer, Stephan

2017-12-01

The rotational spectra of the two stable conformers syn- and gauche-propanal (CH3CH2CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first excited states associated with the aldehyde torsion and with the methyl torsion, respectively, of the syn-conformer were analyzed. The newly obtained spectroscopic parameters yield better predictions, thus fulfill sensitivity and resolution requirements in new astronomical observations in order to unambiguously assign pure rotational transitions of propanal. This is demonstrated on a radio astronomical spectrum from the Atacama Large Millimeter/submillimeter Array Protostellar Interferometric Line Survey (ALMA-PILS). In particular, an accurate description of observed splittings, caused by internal rotation of the methyl group in the syn-conformer and by tunneling rotation interaction from two stable degenerate gauche-conformers, is reported. The rotational spectrum of propanal is of additional interest because of its two large amplitude motions pertaining to the methyl and the aldehyde group, respectively.

Advanced Millimeter-Wave Imaging Enhances Security Screening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheen, David M.; Bernacki, Bruce E.; McMakin, Douglas L.

2012-01-12

Millimeter-wave imaging is rapidly gaining acceptance for passenger screening at airports and other secured facilities. This paper details a number of techniques developed over the last several years including novel image reconstruction and display techniques, polarimetric imaging techniques, array switching schemes, as well as high frequency high bandwidth techniques. Implementation of some of these methods will increase the cost and complexity of the mm-wave security portal imaging systems. RF photonic methods may provide new solutions to the design and development of the sequentially switched linear mm-wave arrays that are the key element in the mm-wave portal imaging systems.

Advanced Millimeter-Wave Security Portal Imaging Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheen, David M.; Bernacki, Bruce E.; McMakin, Douglas L.

2012-04-01

Millimeter-wave imaging is rapidly gaining acceptance for passenger screening at airports and other secured facilities. This paper details a number of techniques developed over the last several years including novel image reconstruction and display techniques, polarimetric imaging techniques, array switching schemes, as well as high frequency high bandwidth techniques. Implementation of some of these methods will increase the cost and complexity of the mm-wave security portal imaging systems. RF photonic methods may provide new solutions to the design and development of the sequentially switched linear mm-wave arrays that are the key element in the mm-wave portal imaging systems.

Millimeter accuracy satellites for two color ranging

NASA Technical Reports Server (NTRS)

Degnan, John J.

1993-01-01

The principal technical challenge in designing a millimeter accuracy satellite to support two color observations at high altitudes is to provide high optical cross-section simultaneously with minimal pulse spreading. In order to address this issue, we provide, a brief review of some fundamental properties of optical retroreflectors when used in spacecraft target arrays, develop a simple model for a spherical geodetic satellite, and use the model to determine some basic design criteria for a new generation of geodetic satellites capable of supporting millimeter accuracy two color laser ranging. We find that increasing the satellite diameter provides: a larger surface area for additional cube mounting thereby leading to higher cross-sections; and makes the satellite surface a better match for the incoming planar phasefront of the laser beam. Restricting the retroreflector field of view (e.g. by recessing it in its holder) limits the target response to the fraction of the satellite surface which best matches the optical phasefront thereby controlling the amount of pulse spreading. In surveying the arrays carried by existing satellites, we find that European STARLETTE and ERS-1 satellites appear to be the best candidates for supporting near term two color experiments in space.

Performance quantification of a millimeter-wavelength imaging system based on inexpensive glow-discharge-detector focal-plane array.

PubMed

Shilemay, Moshe; Rozban, Daniel; Levanon, Assaf; Yitzhaky, Yitzhak; Kopeika, Natan S; Yadid-Pecht, Orly; Abramovich, Amir

2013-03-01

Inexpensive millimeter-wavelength (MMW) optical digital imaging raises a challenge of evaluating the imaging performance and image quality because of the large electromagnetic wavelengths and pixel sensor sizes, which are 2 to 3 orders of magnitude larger than those of ordinary thermal or visual imaging systems, and also because of the noisiness of the inexpensive glow discharge detectors that compose the focal-plane array. This study quantifies the performances of this MMW imaging system. Its point-spread function and modulation transfer function were investigated. The experimental results and the analysis indicate that the image quality of this MMW imaging system is limited mostly by the noise, and the blur is dominated by the pixel sensor size. Therefore, the MMW image might be improved by oversampling, given that noise reduction is achieved. Demonstration of MMW image improvement through oversampling is presented.

Passive front-ends for wideband millimeter wave electronic warfare

NASA Astrophysics Data System (ADS)

Jastram, Nathan Joseph

This thesis presents the analysis, design and measurements of novel passive front ends of interest to millimeter wave electronic warfare systems. However, emerging threats in the millimeter waves (18 GHz and above) has led to a push for new systems capable of addressing these threats. At these frequencies, traditional techniques of design and fabrication are challenging due to small size, limited bandwidth and losses. The use of surface micromachining technology for wideband direction finding with multiple element antenna arrays for electronic support is demonstrated. A wideband tapered slot antenna is first designed and measured as an array element for the subsequent arrays. Both 18--36 GHz and 75--110 GHz amplitude only and amplitude/phase two element direction finding front ends are designed and measured. The design of arrays using Butler matrix and Rotman lens beamformers for greater than two element direction finding over W band and beyond using is also presented. The design of a dual polarized high power capable front end for electronic attack over an 18--45 GHz band is presented. To combine two polarizations into the same radiating aperture, an orthomode transducer (OMT) based upon a new double ridge waveguide cross section is developed. To provide greater flexibility in needed performance characteristics, several different turnstile junction matching sections are tested. A modular horn section is proposed to address flexible and ever changing operational requirements, and is designed for performance criteria such as constant gain, beamwidth, etc. A multi-section branch guide coupler and low loss Rotman lens based upon the proposed cross section are also developed. Prototyping methods for the herein designed millimeter wave electronic warfare front ends are investigated. Specifically, both printed circuit board (PCB) prototyping of micromachined systems and 3D printing of conventionally machined horns are presented. A 4--8 GHz two element array with

The AzTEC millimeter-wave camera: Design, integration, performance, and the characterization of the (sub-)millimeter galaxy population

NASA Astrophysics Data System (ADS)

Austermann, Jason Edward

One of the primary drivers in the development of large format millimeter detector arrays is the study of sub-millimeter galaxies (SMGs) - a population of very luminous high-redshift dust-obscured starbursts that are widely believed to be the dominant contributor to the Far-Infrared Background (FIB). The characterization of such a population requires the ability to map large patches of the (sub-)millimeter sky to high sensitivity within a feasible amount of time. I present this dissertation on the design, integration, and characterization of the 144-pixel AzTEC millimeter-wave camera and its application to the study of the sub-millimeter galaxy population. In particular, I present an unprecedented characterization of the "blank-field" (fields with no known mass bias) SMG number counts by mapping over 0.5 deg^2 to 1.1mm depths of ~1mJy - a previously unattained depth on these scales. This survey provides the tightest SMG number counts available, particularly for the brightest and rarest SMGs that require large survey areas for a significant number of detections. These counts are compared to the predictions of various models of the evolving mm/sub-mm source population, providing important constraints for the ongoing refinement of semi-analytic and hydrodynamical models of galaxy formation. I also present the results of an AzTEC 0.15 deg^2 survey of the COSMOS field, which uncovers a significant over-density of bright SMGs that are spatially correlated to foreground mass structures, presumably as a result of gravitational lensing. Finally, I compare the results of the available SMG surveys completed to date and explore the effects of cosmic variance on the interpretation of individual surveys.

Expanded Owens Valley Solar Array Science and Data Products

NASA Astrophysics Data System (ADS)

Gary, Dale E.; Hurford, G. J.; Nita, G. M.; Fleishman, G. D.; McTiernan, J. M.

2010-05-01

The Owens Valley Solar Array (OVSA) has been funded for major expansion, to create a university-based facility serving a broad scientific community, to keep the U.S. competitive in the field of solar radio physics. The project, funded by the National Science Foundation through the MRI-Recovery and Reinvestment program, will result in a world-class facility for scientific research at microwave radio frequencies (1-18 GHz) in solar and space weather physics. The project also includes an exciting program of targeted astronomical science. The solar science to be addressed focuses on the magnetic structure of the solar corona, on transient phenomena resulting from magnetic interactions, including the sudden release of energy and subsequent particle acceleration and heating, and on space weather phenomena. The project will support the scientific community by providing open data access and software tools for analysis of the data, to exploit synergies with on-going solar research in other wavelength bands. The New Jersey Institute of Technology (NJIT) will upgrade OVSA from its current complement of 7 antennas to a total of 15 by adding 8 new antennas, and will reinvest in the existing infrastructure by replacing the existing control systems, signal transmission, and signal processing with modern, far more capable and reliable systems based on new technology developed for the Frequency Agile Solar Radiotelescope (FASR). The project will be completed in time to provide solar-dedicated observations during the upcoming solar maximum in 2013 and beyond. We will detail the new science addressed by the expanded array, and provide an overview of the expected data products.

High performance millimeter-wave microstrip circulators and isolators

NASA Technical Reports Server (NTRS)

Shih, Ming; Pan, J. J.

1990-01-01

Millimeter wave systems, phased array antennas, and high performance components all require wideband circulators (and isolators) to perform diplexing and switching, to improve isolation and Voltage Standing Wave Ratio (VSWR), and to construct IMPATT diode reflection amplifiers. Presently, most of the millimeter-wave circulators and isolators are available in the configurations of waveguide or stripline, both of which suffer from the shortcomings of bulky size/weight, narrow bandwidth, and poor compatibility with monolithic millimeter-wave integrated circuits (MMIC). MMW microstrip circulators/isolators can eliminate or improve these shortcomings. Stub-tuned microstrip circulator configuration were developed utilizing the electromagnetic fields perturbation technique, the adhesion problems of microstrip metallization on new ferrite substrate were overcome, the fabrication, assembly, packaging techniques were improved, and then successfully designed, fabricated a Ka band circulator which has isolation and return loss of greater than 16dB, insertion loss less than 0.7dB. To assess the steady and reliable performance of the circulator, a temperature cycling test was done over the range of -20 to +50 C for 3 continuous cycles and found no significant impact or variation of circulator performance.

Detection and measurement of land subsidence using Global Positioning System and interferometric synthetic aperture radar, Coachella Valley, California, 1996-98

USGS Publications Warehouse

Sneed, Michelle; Ikehara, Marti E.; Galloway, D.L.; Amelung, Falk

2001-01-01

Land subsidence associated with ground-water-level declines has been recognized as a potential problem in Coachella Valley, California. Since the early 1920s, ground water has been a major source of agricultural, municipal, and domestic supply in the valley, resulting in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the lower Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels from the 1950s through the 1970s. Since the late 1970s, the demand for water in the valley has exceeded the deliveries of imported surface water, again resulting in increased pumping and ground-water-level declines. The magnitude and temporal occurrence of land subsidence in the lower Coachella Valley are not well known; data are sparse and accuracy varies. Also, the area is tectonically active and has subsided during the past several million years, which further complicates interpretations of the data. Land-surface-elevation data have been collected by many agencies using various methods and different geographic scales; because of this, the -150 millimeters (-0.5 foot) of subsidence determined for the southern parts of the valley for 1930-96 may have a possible error of plus or minus (?)90 millimeters (?0.3 foot). The location, extent, and magnitude of vertical land-surface changes from 1996 to 1998 were determined using Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) methods. GPS measurements for 14 monuments in the lower Coachella Valley indicate that the vertical land-surface changes from 1996 to 1998 ranged from -13 to -67 millimeters ? 40 millimeters (-0.04 to -0.22 foot ?0.13 foot). Changes at seven of the monuments exceeded the measurement error of ?40 millimeters (?0.13 foot), which indicates that small amounts of land subsidence occurred at these monuments between 1996 and 1998. Some of the water levels measured

The ASTRI mini-array software system (MASS) implementation: a proposal for the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Tanci, Claudio; Tosti, Gino; Conforti, Vito; Schwarz, Joseph; Antolini, Elisa; Antonelli, L. A.; Bulgarelli, Andrea; Bigongiari, Ciro; Bruno, Pietro; Canestrari, Rodolfo; Capalbi, Milvia; Cascone, Enrico; Catalano, Osvaldo; Di Paola, Andrea; Di Pierro, Federico; Fioretti, Valentina; Gallozzi, Stefano; Gardiol, Daniele; Gianotti, Fulvio; Giro, Enrico; Grillo, Alessandro; La Palombara, Nicola; Leto, Giuseppe; Lombardi, Saverio; Maccarone, Maria C.; Pareschi, Giovanni; Russo, Federico; Sangiorgi, Pierluca; Scuderi, Salvo; Stringhetti, Luca; Testa, Vincenzo; Trifoglio, Massimo; Vercellone, Stefano; Zoli, Andrea

2016-08-01

The ASTRI mini-array, composed of nine small-size dual mirror (SST-2M) telescopes, has been proposed to be installed at the southern site of the Cherenkov Telescope Array (CTA), as a set of preproduction units of the CTA observatory. The ASTRI mini-array is a collaborative and international effort carried out by Italy, Brazil and South Africa and led by the Italian National Institute of Astrophysics, INAF. We present the main features of the current implementation of the Mini-Array Software System (MASS) now in use for the activities of the ASTRI SST-2M telescope prototype located at the INAF observing station on Mt. Etna, Italy and the characteristics that make it a prototype for the CTA control software system. CTA Data Management (CTADATA) and CTA Array Control and Data Acquisition (CTA-ACTL) requirements and guidelines as well as the ASTRI use cases were considered in the MASS design, most of its features are derived from the Atacama Large Millimeter/sub-millimeter Array Control software. The MASS will provide a set of tools to manage all onsite operations of the ASTRI mini-array in order to perform the observations specified in the short term schedule (including monitoring and controlling all the hardware components of each telescope and calibration device), to analyze the acquired data online and to store/retrieve all the data products to/from the onsite repository.

Phased Arrays 1985 Symposium - Proceedings

DTIC Science & Technology

1985-08-01

have served the logic industry well, and appropriate versions can do the same for micruwdve drid millimeter * wave technology, An aspect of phased...continuing revolutions of the logic industry and the microwave monolithic integrated circuit community are bringing relevant technology closer to the array...monolithic phased array antennas, and discuss their relative advantages and disadvantages . Considerations such as bandwidth, maxianiru scan range, feed

Studies of Millimeter-Wave Diffraction Devices and Materials

DTIC Science & Technology

1984-12-28

7.0 REFERENCES 1. Andrenko, S . d., Devyatkov, Acad. N. D., and Shestopalov, V. P., "Millimeter Field Band Antenna Arrays", Dokl. Akad. 4auk SSSR, Vol... S UNCLASSTFIED I* .RIT.Y CL.ASSIFICATION OF THIS PAGE REPORT DOCUMENTATION PAGE :kFPOO- SEURITY CLASSIFICATION 1-b. RESTRICTIVE MARKINGS .EM...State and ZIP Code) 10. SOURCE OF FUNDIN.G NOS. ______ C)c \\~ S PROGRAM PROJECT TASK WORK UNIT 2~~V \\~ ~(~ELEMENT NO. NO. No. NO. ATEinciude Security

General view to the south of the antenna array ...

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

General view to the south of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Detail view to the east of the Antenna Array ...

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

Detail view to the east of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Oblique view to the northwest of the Antenna Array ...

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

Oblique view to the northwest of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

General view to the northwest of the antenna array ...

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

General view to the northwest of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Large-scale transmission-type multifunctional anisotropic coding metasurfaces in millimeter-wave frequencies

NASA Astrophysics Data System (ADS)

Cui, Tie Jun; Wu, Rui Yuan; Wu, Wei; Shi, Chuan Bo; Li, Yun Bo

2017-10-01

We propose fast and accurate designs to large-scale and low-profile transmission-type anisotropic coding metasurfaces with multiple functions in the millimeter-wave frequencies based on the antenna-array method. The numerical simulation of an anisotropic coding metasurface with the size of 30λ × 30λ by the proposed method takes only 20 min, which however cannot be realized by commercial software due to huge memory usage in personal computers. To inspect the performance of coding metasurfaces in the millimeter-wave band, the working frequency is chosen as 60 GHz. Based on the convolution operations and holographic theory, the proposed multifunctional anisotropic coding metasurface exhibits different effects excited by y-polarized and x-polarized incidences. This study extends the frequency range of coding metasurfaces, filling the gap between microwave and terahertz bands, and implying promising applications in millimeter-wave communication and imaging.

Resonant tunneling diodes as sources for millimeter and submillimeter wavelengths

NASA Technical Reports Server (NTRS)

Vanbesien, O.; Bouregba, R.; Mounaix, P.; Lippens, D.; Palmateer, L.; Pernot, J. C.; Beaudin, G.; Encrenaz, P.; Bockenhoff, E.; Nagle, J.

1992-01-01

High-quality Resonant Tunneling Diodes have been fabricated and tested as sources for millimeter and submillimeter wavelengths. The devices have shown excellent I-V characteristics with peak-to-valley current ratios as high as 6:1 and current densities in the range of 50-150 kA/cm(exp 2) at 300 K. Used as local oscillators, the diodes are capable of state of the art output power delivered by AlGaAs-based tunneling devices. As harmonic multipliers, a frequency of 320 GHz has been achieved by quintupling the fundamental oscillation of a klystron source.

Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter

NASA Astrophysics Data System (ADS)

Bower, Geoffrey C.; Markoff, Sera; Dexter, Jason; Gurwell, Mark A.; Moran, James M.; Brunthaler, Andreas; Falcke, Heino; Fragile, P. Chris; Maitra, Dipankar; Marrone, Dan; Peck, Alison; Rushton, Anthony; Wright, Melvyn C. H.

2015-03-01

We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between 2012 October and 2014 November. While we see variability over the whole spectrum with an amplitude as large as a factor of 2 at millimeter wavelengths, we find no evidence for a change in the mean flux density or spectrum of Sgr A* that can be attributed to interaction with the G2 source. The absence of a bow shock at low frequencies is consistent with a cross-sectional area for G2 that is less than 2× {10}29 cm2. This result fits with several model predictions including a magnetically arrested cloud, a pressure-confined stellar wind, and a stellar photosphere of a binary merger. There is no evidence for enhanced accretion onto the black hole driving greater jet and/or accretion flow emission. Finally, we measure the millimeter wavelength spectral index of Sgr A* to be flat; combined with previous measurements, this suggests that there is no spectral break between 230 and 690 GHz. The emission region is thus likely in a transition between optically thick and thin at these frequencies and requires a mix of lepton distributions with varying temperatures consistent with stratification.

View to the northeast of the antenna array OvertheHorizon ...

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

View to the northeast of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

View to the east of the Antenna Array OvertheHorizon ...

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

View to the east of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Detecting Extrasolar Planets With Millimeter-Wave Observatories

NASA Astrophysics Data System (ADS)

1996-01-01

. Another important advantage is that, at millimeter wavelengths, the star's brightness poses less of a problem for observers because, while it is still brighter than a planet, the difference in brightness between the two is far less. Because of the physical nature of the objects themselves, protoplanets in different stages of formation could readily be detected by advanced millimeter-wave observatories. The observatories that could provide these advantages are the Millimeter Array (MMA), a proposed 40-antenna millimeter-wave telescope that could be operational by 2005, and an upgraded version of the existing Very Large Array (VLA), a 27-antenna radio telescope in New Mexico. The MMA is a radio telescope designed to operate at wavelengths from 11.5 millimeters down to 0.5 millimeters, or frequencies from 26 to 650 GHz. It will use 40 precision antennas, each 8 meters in diameter, all operating in concert to produce extremely high- resolution images. As is done with the existing VLA and VLBA radio telescopes, the signals from all the MMA antennas will be processed in a special-purpose computer called a correlator. The processing of the signals corrects for atmospheric propagation effects and for the fact that the "synthesized telescope" is in fact made up of individual antennas. Planning for the MMA began as early as 1983, and a number of scientific workshops have allowed U.S. researchers to make known their needs for a millimeter-wave observatory to serve a wide variety of specialties. The National Science Foundation (NSF) provided initial design funding to NRAO in 1995 for MMA studies. Currently, MMA efforts are centered on selecting an appropriate site, which must be very high, dry and flat. A site at 16,500 feet elevation in northern Chile is now being tested. Hawaii's Mauna Kea is also under consideration. If funding is approved for the MMA, the instrument could be in operation by the year 2005. The MMA is expected to be an international instrument, with funding from

View to the eastnortheast of the Antenna Array OvertheHorizon ...

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

View to the east-northeast of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

The Millimeter-Wave Spectrum of Propanal

NASA Astrophysics Data System (ADS)

Zingsheim, Oliver; Müller, Holger S. P.; Lewen, Frank; Schlemmer, Stephan

2017-06-01

The microwave spectrum of propanal, also known as propionaldehyde, CH_3CH_2CHO, has been investigated in the laboratory already since 1964^1 and has also been detected in space^2. Recently, propanal was detected with the Atacama Large Millimeter/submillimeter Array (ALMA), Protostellar Interferometric Line Survey (PILS)^3. The high sensitivity and resolution of ALMA indicated small discrepancies between observed and predicted rotational spectra of propanal. As higher accuracies are desired the spectrum of propanal was measured up to 500 GHz with the Cologne (Sub-)Millimeter spectrometer. Propanal has two stable conformers, syn and gauche, which differ mainly in the rotation of the aldehyd group with respect to the rigid C-atom framework of the molecule. We extensively studied both of them. The lower syn-conformer shows small splittings caused by the internal rotation of the methyl group, whereas the spectrum of gauche-propanal is complicated due to the tunneling rotation interaction from two stable degenerate conformers. Additionally, we analyzed vibrationally excited states. ^1 Butcher et al., J. Chem. Phys. 40 6 (1964) ^2 Hollis et al., Astrophys. J. 610 L21 (2004) ^3 Lykke et al., A&A 597 A53 (2017)

INTERFEROMETRIC UPPER LIMITS ON MILLIMETER POLARIZATION OF THE DISKS AROUND DG Tau, GM Aur, AND MWC 480

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, A. Meredith; Hull, Charles L. H.; Plambeck, Richard L.

2013-04-15

Millimeter-wavelength polarization measurements offer a promising method for probing the geometry of magnetic fields in circumstellar disks. Single dish observations and theoretical work have hinted that magnetic field geometries might be predominantly toroidal, and that disks should exhibit millimeter polarization fractions of 2%-3%. While subsequent work has not confirmed these high polarization fractions, either the wavelength of observation or the target sources differed from the original observations. Here we present new polarimetric observations of three nearby circumstellar disks at 2'' resolution with the Submillimeter Array and the Combined Array for Research in Millimeter Astronomy. We reobserve GM Aur and DGmore » Tau, the systems in which millimeter polarization detections have been claimed. Despite higher resolution and sensitivity at wavelengths similar to the previous observations, the new observations do not show significant polarization. We also add observations of a new HAeBe system, MWC 480. These observations demonstrate that a very low ({approx}<0.5%) polarization fraction is probably common at large ({approx}>100 AU) scales in bright circumstellar disks. We suggest that high-resolution observations may be worthwhile to probe magnetic field structure on linear distances smaller than the disk scale height, as well as in regions closer to the star that may have larger MRI-induced magnetic field strengths.« less

View north of the antenna array, note the communications antenna ...

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

View north of the antenna array, note the communications antenna in the middleground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Kinetic inductance detectors for millimeter and submillimeter astronomy

NASA Astrophysics Data System (ADS)

Boudou, Nicolas; Benoit, Alain; Bourrion, Olivier; Calvo, Martino; Désert, François-Xavier; Macias-Perez, Juan; Monfardini, Alessandro; Roesch, Markus

2012-01-01

We present recent developments in Kinetic Inductance Detectors (KID) for large arrays of detectors. The main application is ground-based millimeter wave astronomy. We focus in particular, as a case study, on our own experiment: NIKA (Néel IRAM KID Arrays). NIKA is today the best in-the-field experiment using KID-based instruments, and consists of a dual-band imaging system designed for the IRAM 30 meter telescope at Pico Veleta. We describe in this article, after a general context introduction, the KID working principle and the readout electronics, crucial to take advantage of the intrinsic KID multiplexability. We conclude with a small subset of the astronomical sources observed simultaneously at 2 mm and 1.4 mm by NIKA during the last run, held in October 2010.

ALMA Partners Break Ground on World's Largest Millimeter Wavelength Telescope

NASA Astrophysics Data System (ADS)

2003-11-01

Scientists and dignitaries from North America, Europe, and Chile broke ground today (Thursday, November 6, 2003) on what will be the world's largest, most sensitive radio telescope operating at millimeter wavelengths. ALMA - the Atacama Large Millimeter Array - will be a single instrument composed of 64 high-precision antennas located on the Chajnantor plain of the Chilean Andes in the District of San Pedro de Atacama, 16,500 feet (5,000 meters) above sea level. ALMA's primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimeter portion of the electromagnetic spectrum. ALMA Array Artist's Conception of ALMA Array in Compact Configuration (Click on Image for Larger Version) Other Images Available: Artist's conception of the antennas for the Atacama Large Millimeter Array Moonrise over ALMA test equipment near Cerro Chajnantor, Chile VertexRSI antenna at the VLA test site The Atacama Large Millimeter Array is an international astronomy facility. ALMA is an equal partnership between Europe and North America, in cooperation with the Republic of Chile, and is funded in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC), and in Europe by the European Southern Observatory (ESO) and Spain. ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI), and on behalf of Europe by ESO. "The U.S. National Science Foundation joins today with our North American partner, Canada, and with the European Southern Observatory, Spain, and Chile to prepare for a spectacular new instrument," said Dr. Rita Colwell, director of the U.S. National Science Foundation. "The Atacama Large Millimeter Array will expand our vision of the Universe with "eyes" that pierce the shrouded mantles of

The ALMA Phasing System: A Beamforming Capability for Ultra-high-resolution Science at (Sub)Millimeter Wavelengths

NASA Astrophysics Data System (ADS)

Matthews, L. D.; Crew, G. B.; Doeleman, S. S.; Lacasse, R.; Saez, A. F.; Alef, W.; Akiyama, K.; Amestica, R.; Anderson, J. M.; Barkats, D. A.; Baudry, A.; Broguière, D.; Escoffier, R.; Fish, V. L.; Greenberg, J.; Hecht, M. H.; Hiriart, R.; Hirota, A.; Honma, M.; Ho, P. T. P.; Impellizzeri, C. M. V.; Inoue, M.; Kohno, Y.; Lopez, B.; Martí-Vidal, I.; Messias, H.; Meyer-Zhao, Z.; Mora-Klein, M.; Nagar, N. M.; Nishioka, H.; Oyama, T.; Pankratius, V.; Perez, J.; Phillips, N.; Pradel, N.; Rottmann, H.; Roy, A. L.; Ruszczyk, C. A.; Shillue, B.; Suzuki, S.; Treacy, R.

2018-01-01

The Atacama Millimeter/submillimeter Array (ALMA) Phasing Project (APP) has developed and deployed the hardware and software necessary to coherently sum the signals of individual ALMA antennas and record the aggregate sum in Very Long Baseline Interferometry (VLBI) Data Exchange Format. These beamforming capabilities allow the ALMA array to collectively function as the equivalent of a single large aperture and participate in global VLBI arrays. The inclusion of phased ALMA in current VLBI networks operating at (sub)millimeter wavelengths provides an order of magnitude improvement in sensitivity, as well as enhancements in u–v coverage and north–south angular resolution. The availability of a phased ALMA enables a wide range of new ultra-high angular resolution science applications, including the resolution of supermassive black holes on event horizon scales and studies of the launch and collimation of astrophysical jets. It also provides a high-sensitivity aperture that may be used for investigations such as pulsar searches at high frequencies. This paper provides an overview of the ALMA Phasing System design, implementation, and performance characteristics.

Evapotranspiration from forage grass replacing native vegetation in the Gila River valley of Arizona

USGS Publications Warehouse

Leppanen, O.E.

1981-01-01

Estimates of evapotranspiration from an area of forage grass, which had been planted to replace native vegetation of little economic value, were made daily for a 363-day period in 1969 and 1970. The measurement site was located in the Gila River valley in east-central Arizona. The forage, panigrass (Panicum antidotale Retz.), grew from seed during the early summer of 1969 and after winterkill, regrew in 1970. Daily evapotranspiration estimates, which were based on energy budget measurements, ranged from a maximum of 9.2 millimeters to small amounts of condensation. Two daily values of substantial condensation (0.9 and 0.4 millimeter) were of dubious quality, but were retained in the record. The annual evapotranspiration was 989 millimeters, of which about 332 millimeters came from precipitation at the site. The water table fluctuated between 210 and 280 centimeters below land surface. However, the measurement site was near a wash, so that undocumented, shallower subterranean flows may have occurred. (USGS)

View to the southwest of the antenna array, note the ...

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

View to the southwest of the antenna array, note the site fence in the foreground - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Controlled Synthesis of Millimeter-Long Silicon Nanowires with Uniform Electronic Properties

PubMed Central

Park, Won Il; Zheng, Gengfeng; Jiang, Xiaocheng; Tian, Bozhi; Lieber, Charles M.

2009-01-01

We report the nanocluster-catalyzed growth of ultra-long and highly-uniform single-crystalline silicon nanowires (SiNWs) with millimeter-scale lengths and aspect ratios up to ca. 100,000. The average SiNW growth rate using disilane (Si2H6) at 400 °C was 31 µm/min, while the growth rate determined for silane (SiH4) reactant under similar growth conditions was 130 times lower. Transmission electron microscopy studies of millimeter-long SiNWs with diameters of 20–80 nm show that the nanowires grow preferentially along the <110> direction independent of diameter. In addition, ultra-long SiNWs were used as building blocks to fabricate one-dimensional arrays of field-effect transistors (FETs) consisting of ca. 100 independent devices per nanowire. Significantly, electrical transport measurements demonstrated that the millimeter-long SiNWs had uniform electrical properties along the entire length of wires, and each device can behave as a reliable FET with an on-state current, threshold voltage, and transconductance values (average ± 1 standard deviation) of 1.8 ± 0.3 µA, 6.0 ± 1.1 V, 210 ± 60 nS, respectively. Electronically-uniform millimeter-long SiNWs were also functionalized with monoclonal antibody receptors, and used to demonstrate multiplexed detection of cancer marker proteins with a single nanowire. The synthesis of structurally- and electronically-uniform ultra-long SiNWs may open up new opportunities for integrated nanoelectronics, and could serve as unique building blocks linking integrated structures from the nanometer through millimeter length scales. PMID:18710294

Advanced millimeter-wave security portal imaging techniques

NASA Astrophysics Data System (ADS)

Sheen, David M.; Bernacki, Bruce E.; McMakin, Douglas L.

2012-03-01

Millimeter-wave (mm-wave) imaging is rapidly gaining acceptance as a security tool to augment conventional metal detectors and baggage x-ray systems for passenger screening at airports and other secured facilities. This acceptance indicates that the technology has matured; however, many potential improvements can yet be realized. The authors have developed a number of techniques over the last several years including novel image reconstruction and display techniques, polarimetric imaging techniques, array switching schemes, and high-frequency high-bandwidth techniques. All of these may improve the performance of new systems; however, some of these techniques will increase the cost and complexity of the mm-wave security portal imaging systems. Reducing this cost may require the development of novel array designs. In particular, RF photonic methods may provide new solutions to the design and development of the sequentially switched linear mm-wave arrays that are the key element in the mm-wave portal imaging systems. Highfrequency, high-bandwidth designs are difficult to achieve with conventional mm-wave electronic devices, and RF photonic devices may be a practical alternative. In this paper, the mm-wave imaging techniques developed at PNNL are reviewed and the potential for implementing RF photonic mm-wave array designs is explored.

Large-Aperture Wide-Bandwidth Anti-Reflection-Coated Silicon Lenses for Millimeter Wavelengths

NASA Technical Reports Server (NTRS)

Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, E. J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.;

Detection and Measurement of Land Subsidence Using Global Positioning System Surveying and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1996-2005

USGS Publications Warehouse

Sneed, Michelle; Brandt, Justin T.

2007-01-01

Land subsidence associated with ground-water-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Ground water has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of ground water resulted in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated ground-water-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and interferometric synthetic aperture radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley. GPS measurements made at 13 geodetic monuments in 1996 and in 2005 in the southern Coachella Valley indicate that the elevation of the land surface had a net decline of 333 to 22 millimeters ?58 millimeters (1.1 to 0.07 foot ?0.19 foot) during the 9-year period. Changes at 10 of the 13 monuments exceeded the maximum uncertainty of ?58 millimeters (?0.19 foot) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2005. GPS measurements made at 20 geodetic monuments in 2000 and in 2005 indicate that the elevation of the land surface changed -312 to +25 millimeters ?42 millimeters (-1.0 to +0.08 foot ?0.14 foot) during the 5-year period. Changes at 14 of the 20 monuments exceeded the maximum uncertainty of ?42 millimeters (?0.14 foot) at the 95-percent confidence level, indicating that subsidence occurred at

Broad-bandwidth Metamaterial Antireflection Coatings for Sub-Millimeter Astronomy and CMB Foreground Removal

NASA Astrophysics Data System (ADS)

McMahon, Jeff

Sub-millimeter observations are crucial for answering questions about star and galaxy formation; understanding galactic dust foregrounds; and for removing these foregrounds to detect the faint signature of inflationary gravitational waves in the polarization of the Cosmic Microwave Background (CMB). Achieving these goals requires improved, broad-band antireflection coated lenses and half-wave plates (HWPs). These optical elements will significantly boost the sensitivity and capability of future sub-millimeter and CMB missions. We propose to develop wide-bandwidth metamaterial antireflection coatings for silicon lenses and sapphire HWPs with 3:1 ratio bandwidth that are scalable across the sub-millimeter band from 300 GHz to 3 THz. This is an extension of our successful work on saw cut metamaterial AR coatings for silicon optics at millimeter wave lengths. These, and the proposed coatings consist of arrays of sub-wavelength scale features cut into optical surfaces that behave like simple dielectrics. We have demonstrated saw cut 3:1 bandwidth coatings on silicon lenses, but these coatings are limited to the millimeter wave band by the limitations of dicing saw machining. The crucial advance needed to extend these broad band coatings throughout the sub-millimeter band is the development of laser cut graded index metamaterial coatings. The proposed work includes developing the capability to fabricate these coatings, optimizing the design of these metamaterials, fabricating and testing prototype lenses and HWPs, and working with the PIPER collaboration to achieve a sub-orbital demonstration of this technology. The proposed work will develop potentially revolutionary new high performance coatings for the sub-millimeter bands, and cary this technology to TRL 7 paving the way for its use in space. We anticipate that there will be a wide range of applications for these coatings on future NASA balloons and satellites.

Millimeter-scale epileptiform spike propagation patterns and their relationship to seizures

PubMed Central

Vanleer, Ann C; Blanco, Justin A; Wagenaar, Joost B; Viventi, Jonathan; Contreras, Diego; Litt, Brian

2016-01-01

Objective Current mapping of epileptic networks in patients prior to epilepsy surgery utilizes electrode arrays with sparse spatial sampling (∼1.0 cm inter-electrode spacing). Recent research demonstrates that sub-millimeter, cortical-column-scale domains have a role in seizure generation that may be clinically significant. We use high-resolution, active, flexible surface electrode arrays with 500 μm inter-electrode spacing to explore epileptiform local field potential spike propagation patterns in two dimensions recorded from subdural micro-electrocorticographic signals in vivo in cat. In this study, we aimed to develop methods to quantitatively characterize the spatiotemporal dynamics of epileptiform activity at high-resolution. Approach We topically administered a GABA-antagonist, picrotoxin, to induce acute neocortical epileptiform activity leading up to discrete electrographic seizures. We extracted features from local field potential spikes to characterize spatiotemporal patterns in these events. We then tested the hypothesis that two dimensional spike patterns during seizures were different from those between seizures. Main results We showed that spatially correlated events can be used to distinguish ictal versus interictal spikes. Significance We conclude that sub-millimeter-scale spatiotemporal spike patterns reveal network dynamics that are invisible to standard clinical recordings and contain information related to seizure-state. PMID:26859260

Millimeter-scale epileptiform spike propagation patterns and their relationship to seizures

NASA Astrophysics Data System (ADS)

Vanleer, Ann C.; Blanco, Justin A.; Wagenaar, Joost B.; Viventi, Jonathan; Contreras, Diego; Litt, Brian

2016-04-01

Objective. Current mapping of epileptic networks in patients prior to epilepsy surgery utilizes electrode arrays with sparse spatial sampling (∼1.0 cm inter-electrode spacing). Recent research demonstrates that sub-millimeter, cortical-column-scale domains have a role in seizure generation that may be clinically significant. We use high-resolution, active, flexible surface electrode arrays with 500 μm inter-electrode spacing to explore epileptiform local field potential (LFP) spike propagation patterns in two dimensions recorded from subdural micro-electrocorticographic signals in vivo in cat. In this study, we aimed to develop methods to quantitatively characterize the spatiotemporal dynamics of epileptiform activity at high-resolution. Approach. We topically administered a GABA-antagonist, picrotoxin, to induce acute neocortical epileptiform activity leading up to discrete electrographic seizures. We extracted features from LFP spikes to characterize spatiotemporal patterns in these events. We then tested the hypothesis that two-dimensional spike patterns during seizures were different from those between seizures. Main results. We showed that spatially correlated events can be used to distinguish ictal versus interictal spikes. Significance. We conclude that sub-millimeter-scale spatiotemporal spike patterns reveal network dynamics that are invisible to standard clinical recordings and contain information related to seizure-state.

Combined illumination cylindrical millimeter-wave imaging technique for concealed weapon detection

NASA Astrophysics Data System (ADS)

Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

2000-07-01

A novel millimeter-wave imaging technique has been developed for personnel surveillance applications, including the detection of concealed weapons, explosives, drugs, and other contraband material. Millimeter-waves are high-frequency radio waves in the frequency band of 30 - 300 GHz, and pose no health threat to humans at moderate power levels. These waves readily penetrate common clothing materials, and are reflected by the human body and by concealed items. The combined illumination cylindrical imaging concept consists of a vertical, high-resolution, millimeter-wave array of antennas which is scanned in a cylindrical manner about the person under surveillance. Using a computer, the data from this scan is mathematically reconstructed into a series of focused 3D images of the person. After reconstruction, the images are combined into a single high-resolution 3D image of the person under surveillance. This combined image is then rendered using 3D computer graphics techniques. The combined cylindrical illumination is critical as it allows the display of information from all angles. This is necessary because millimeter-waves do not penetrate the body. Ultimately, the images displayed to the operate will be icon-based to protect the privacy of the person being screened. Novel aspects of this technique include the cylindrical scanning concept and the image reconstruction algorithm, which was developed specifically for this imaging system. An engineering prototype based on this cylindrical imaging technique has been fabricated and tested. This work has been sponsored by the Federal Aviation Administration.

Analysis of seismic waves crossing the Santa Clara Valley using the three-component MUSIQUE array algorithm

NASA Astrophysics Data System (ADS)

Hobiger, Manuel; Cornou, Cécile; Bard, Pierre-Yves; Le Bihan, Nicolas; Imperatori, Walter

2016-10-01

We introduce the MUSIQUE algorithm and apply it to seismic wavefield recordings in California. The algorithm is designed to analyse seismic signals recorded by arrays of three-component seismic sensors. It is based on the MUSIC and the quaternion-MUSIC algorithms. In a first step, the MUSIC algorithm is applied in order to estimate the backazimuth and velocity of incident seismic waves and to discriminate between Love and possible Rayleigh waves. In a second step, the polarization parameters of possible Rayleigh waves are analysed using quaternion-MUSIC, distinguishing retrograde and prograde Rayleigh waves and determining their ellipticity. In this study, we apply the MUSIQUE algorithm to seismic wavefield recordings of the San Jose Dense Seismic Array. This array has been installed in 1999 in the Evergreen Basin, a sedimentary basin in the Eastern Santa Clara Valley. The analysis includes 22 regional earthquakes with epicentres between 40 and 600 km distant from the array and covering different backazimuths with respect to the array. The azimuthal distribution and the energy partition of the different surface wave types are analysed. Love waves dominate the wavefield for the vast majority of the events. For close events in the north, the wavefield is dominated by the first harmonic mode of Love waves, for farther events, the fundamental mode dominates. The energy distribution is different for earthquakes occurring northwest and southeast of the array. In both cases, the waves crossing the array are mostly arriving from the respective hemicycle. However, scattered Love waves arriving from the south can be seen for all earthquakes. Combining the information of all events, it is possible to retrieve the Love wave dispersion curves of the fundamental and the first harmonic mode. The particle motion of the fundamental mode of Rayleigh waves is retrograde and for the first harmonic mode, it is prograde. For both modes, we can also retrieve dispersion and ellipticity

Design and performance of dual-polarization lumped-element kinetic inductance detectors for millimeter-wave polarimetry

NASA Astrophysics Data System (ADS)

McCarrick, H.; Jones, G.; Johnson, B. R.; Abitbol, M. H.; Ade, P. A. R.; Bryan, S.; Day, P.; Essinger-Hileman, T.; Flanigan, D.; Leduc, H. G.; Limon, M.; Mauskopf, P.; Miller, A.; Tucker, C.

2018-02-01

Aims: Lumped-element kinetic inductance detectors (LEKIDs) are an attractive technology for millimeter-wave observations that require large arrays of extremely low-noise detectors. We designed, fabricated and characterized 64-element (128 LEKID) arrays of horn-coupled, dual-polarization LEKIDs optimized for ground-based CMB polarimetry. Our devices are sensitive to two orthogonal polarizations in a single spectral band centered on 150 GHz with Δν/ν = 0.2. The 65 × 65 mm square arrays are designed to be tiled into the focal plane of an optical system. We demonstrate the viability of these dual-polarization LEKIDs with laboratory measurements. Methods: The LEKID modules are tested with an FPGA-based readout system in a sub-kelvin cryostat that uses a two-stage adiabatic demagnetization refrigerator. The devices are characterized using a blackbody and a millimeter-wave source. The polarization properties are measured with a cryogenic stepped half-wave plate. We measure the resonator parameters and the detector sensitivity, noise spectrum, dynamic range, and polarization response. Results: The resonators have internal quality factors approaching 1 × 106. The detectors have uniform response between orthogonal polarizations and a large dynamic range. The detectors are photon-noise limited above 1 pW of absorbed power. The noise-equivalent temperatures under a 3.4 K blackbody load are <100 μK √s. The polarization fractions of detectors sensitive to orthogonal polarizations are >80%. The entire array is multiplexed on a single readout line, demonstrating a multiplexing factor of 128. The array and readout meet the requirements for 4 arrays to be read out simultaneously for a multiplexing factor of 512. Conclusions: This laboratory study demonstrates the first dual-polarization LEKID array optimized specifically for CMB polarimetry and shows the readiness of the detectors for on-sky observations.

Detection and Measurement of Land Subsidence Using Global Positioning System and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1998-2000

USGS Publications Warehouse

Sneed, Michelle; Stork, Sylvia V.; Ikehara, Marti E.

2002-01-01

Land subsidence associated with ground-water-level declines has been recognized as a potential problem in Coachella Valley, California. Since the early 1920s, ground water has been a major source of agricultural, municipal, and domestic supply in the valley. Pumping of ground water resulted in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the lower Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated ground-water-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. The location, extent, and magnitude of the vertical land-surface changes in Coachella Valley between 1998 and 2000 were determined using Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) methods. GPS measurements made at 15 geodetic monuments in the lower Coachella Valley indicate that -34 to +60 millimeters ? 45 millimeters (-0.11 to +0.20 foot ? 0.15 foot) of vertical change in the land surface occurred during the 2-year period. Changes at three of the monuments exceeded the maximum uncertainty of ? 45 millimeters (? 0.15 foot) at the 95-percent confidence level, which indicates that small amounts of uplift occurred at these monuments between October 1998 and August 2000. Water-level measurements made at wells near the three uplifted monuments during this 2-year period indicate that the water levels fluctuate seasonally; water-level measurements made at these wells in September 1998 and September 2000 indicate that the water levels rose slightly near two monuments and declined slightly near the third. The relation between the seasonally fluctuating, but fairly stable, water levels between

Semiconductor millimeter wavelength electronics

NASA Astrophysics Data System (ADS)

Rosenbaum, F. J.

1985-12-01

This final report summarizes the results of research carried out on topics in millimeter wavelength semiconductor electronics under an ONR Selected Research Opportunity program. Study areas included III-V compound semiconductor growth and characterization, microwave and millimeter wave device modeling, fabrication and testing, and the development of new device concepts. A new millimeter wave mixer and detector, the Gap diode was invented. Topics reported on include ballistic transport, Zener oscillations, impurities in GaAs, electron velocity-electric field calculation and measurements, etc., calculations.

SMURF: SubMillimeter User Reduction Facility

NASA Astrophysics Data System (ADS)

Jenness, Tim; Chapin, Edward L.; Berry, David S.; Gibb, Andy G.; Tilanus, Remo P. J.; Balfour, Jennifer; Tilanus, Vincent; Currie, Malcolm J.

2013-10-01

SMURF reduces submillimeter single-dish continuum and heterodyne data. It is mainly targeted at data produced by the James Clerk Maxwell Telescope but data from other telescopes have been reduced using the package. SMURF is released as part of the bundle that comprises Starlink (ascl:1110.012) and most of the packages that use it. The two key commands are MAKEMAP for the creation of maps from sub millimeter continuum data and MAKECUBE for the creation of data cubes from heterodyne array instruments. The software can also convert data from legacy JCMT file formats to the modern form to allow it to be processed by MAKECUBE. SMURF is a core component of the ORAC-DR (ascl:1310.001) data reduction pipeline for JCMT.

Millimeter waves: acoustic and electromagnetic.

PubMed

Ziskin, Marvin C

2013-01-01

This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. Copyright © 2012 Wiley Periodicals, Inc.

ALMA 26 arcmin2 Survey of GOODS-S at One-millimeter (ASAGAO): X-Ray AGN Properties of Millimeter-selected Galaxies

NASA Astrophysics Data System (ADS)

Ueda, Y.; Hatsukade, B.; Kohno, K.; Yamaguchi, Y.; Tamura, Y.; Umehata, H.; Akiyama, M.; Ao, Y.; Aretxaga, I.; Caputi, K.; Dunlop, J. S.; Espada, D.; Fujimoto, S.; Hayatsu, N. H.; Imanishi, M.; Inoue, A. K.; Ivison, R. J.; Kodama, T.; Lee, M. M.; Matsuoka, K.; Miyaji, T.; Morokuma-Matsui, K.; Nagao, T.; Nakanishi, K.; Nyland, K.; Ohta, K.; Ouchi, M.; Rujopakarn, W.; Saito, T.; Tadaki, K.; Tanaka, I.; Taniguchi, Y.; Wang, T.; Wang, W.-H.; Yoshimura, Y.; Yun, M. S.

2018-01-01

We investigate the X-ray active galactic nucleus (AGN) properties of millimeter galaxies in the Great Observatories Origins Deep Survey South (GOODS-S) field detected with the Atacama Large Millimeter/submillimeter Array (ALMA), by utilizing the Chandra 7-Ms data, the deepest X-ray survey to date. Our millimeter galaxy sample comes from the ASAGAO survey covering 26 arcmin2 (12 sources at a 1.2 mm flux-density limit of ≈ 0.6 mJy), supplemented by the deeper but narrower 1.3 mm survey of a part of the ASAGAO field by Dunlop et al. Ofthe 25 total millimeter galaxies, 14 have Chandra counterparts. The observed AGN fractions at z=1.5{--}3 are found to be {90}-19+8% and {57}-25+23% for the ultra-luminous and luminous infrared galaxies with log {L}{IR}/{L}ȯ = 12–12.8 and log {L}{IR}/{L}ȯ = 11.5–12, respectively. The majority (∼2/3) of the ALMA and/or Herschel detected X-ray AGNs at z = 1.5‑3 appear to be star-formation-dominant populations, having {L}{{X}}/ {L}{IR} ratios smaller than the “simultaneous evolution” value expected from the local black-hole-mass-to-stellar-mass ({M}{BH}–M *) relation. On the basis of the {L}{{X}} and stellar mass relation, we infer that a large fraction of star-forming galaxies at z=1.5{--}3 have black hole masses that are smaller than those expected from the local {M}{BH}–M * relation. This contrasts previous reports on luminous AGNs at the same redshifts detected in wider and shallower surveys, which are subject to selection biases against lower luminosity AGNs. Our results are consistent with an evolutionary scenario in which star formation occurs first, and an AGN-dominant phase follows later, in objects that finally evolve into galaxies with classical bulges.

Laboratory Measurements of Sulfuric Acid Vapor Opacity at Millimeter Wavelengths Under Venus Conditions

NASA Astrophysics Data System (ADS)

Akins, Alexander Brooks; Steffes, Paul G.

2017-10-01

Radio astronomical observations of the lower-cloud and sub-cloud regions of the Venusian atmosphere at millimeter wavelengths can provide insight into the nature of the sub-cloud sulfur chemistry. Previous observations (de Pater et al., Icarus 90, 1991 and Sagawa, J. Natl. Inst. of Inf. And Comm. Tech. 55, 2008) indicate substantial variations in Venus disc brightness at millimeter wavelengths, likely due to variations in SO2 and H2SO4 vapor abundances. Although previous measurements of H2SO4 vapor opacity provide accurate information at centimeter wavelengths (Kolodner and Steffes, Icarus 132, 1998), extrapolation to millimeter wavelength observations is speculative. A Fabry-Perot open resonator with a quality factor in excess of 15,000 has been designed to measure the opacity of H2SO4 vapor in a CO2 atmosphere under Venus temperature and pressure conditions below the clouds. The resonator system has been designed using corrosion-resistant materials to ensure data integrity. Opacity measurements made with this system target the 2-4 millimeter wavelength range, applicable to recent Atacama Large Millimeter Array observations of Venus. Initial laboratory results for H2SO4 vapor opacity will be presented, and the implications of these results for pressure broadened opacity formalisms will be discussed. In addition to radio astronomical observations, these results of these measurements can aid in the interpretation of radiometer and radio occultation measurements from future Venus missions, such as the Venera D orbiter. This work is supported by the NASA Solar System Workings Program under grant NNX17AB19G.

Method and apparatus for millimeter-wave detection of thermal waves for materials evaluation

DOEpatents

Gopalsami, Nachappa; Raptis, Apostolos C.

1991-01-01

A method and apparatus for generating thermal waves in a sample and for measuring thermal inhomogeneities at subsurface levels using millimeter-wave radiometry. An intensity modulated heating source is oriented toward a narrow spot on the surface of a material sample and thermal radiation in a narrow volume of material around the spot is monitored using a millimeter-wave radiometer; the radiometer scans the sample point-by-point and a computer stores and displays in-phase and quadrature phase components of thermal radiations for each point on the scan. Alternatively, an intensity modulated heating source is oriented toward a relatively large surface area in a material sample and variations in thermal radiation within the full field of an antenna array are obtained using an aperture synthesis radiometer technique.

Millimeter wavelength propagation studies

NASA Technical Reports Server (NTRS)

Hodge, D. B.

1974-01-01

The investigations conducted for the Millimeter Wavelength Propagation Studies during the period December, 1966, to June 1974 are reported. These efforts included the preparation for the ATS-5 Millimeter Wavelength Propagation Experiment and the subsequent data acquisition and data analysis. The emphasis of the OSU participation in this experiment was placed on the determination of reliability improvement resulting from the use of space diversity on a millimeter wavelength earth-space communication link. Related measurements included the determination of the correlation between radiometric temperature and attenuation along the earth-space propagation path. Along with this experimental effort a theoretical model was developed for the prediction of attenuation statistics on single and spatially separated earth space propagation paths. A High Resolution Radar/Radiometer System and Low Resolution Radar System were developed and implemented for the study of intense rain cells in preparation for the ATS-6 Millimeter Wavelength Propagation Experiment.

Nova Oph 2017 (TCP J17394608-2457555) detected at millimeter wavelengths

NASA Astrophysics Data System (ADS)

Kaminski, T.; Gehrz, R.

2017-06-01

Millimeter-wave continuum emission was detected in Nova Oph 2017 (ATel #10366, #10367) with the Submillimeter Array in Hawaii. The object was observed on July 20, 2017 in four spectral ranges: 224.3-232.3, 240.6-248.6, 336-344, and 352-360 GHz. The combined continuum flux in the two lower ranges (i.e., at a wavelength of 1.3 mm) is of 4.8 mJy, well above the noise with an rms of 0.6 mJy per beam.

Unidirectional waveguide grating antennas with uniform emission for optical phased arrays.

PubMed

Raval, Manan; Poulton, Christopher V; Watts, Michael R

2017-07-01

We demonstrate millimeter-scale optical waveguide grating antennas with unidirectional emission for integrated optical phased arrays. Unidirectional emission eliminates the fundamental problem of blind spots in the element factor of a phased array caused by reflections of antenna radiation within the substrate. Over 90% directionality is demonstrated using a design consisting of two silicon nitride layers. Furthermore, the perturbation strength along the antenna is apodized to achieve uniform emission for the first time, to the best of our knowledge, on a millimeter scale. This allows for a high effective aperture and receiving efficiency. The emission profile of the measured 3 mm long antenna has a standard deviation of 8.65% of the mean. These antennas are state of the art and will allow for integrated optical phased arrays with blind-spot-free high transmission output power and high receiving efficiency for LIDAR and free-space communication systems.

A dual-polarized broadband planar antenna and channelizing filter bank for millimeter wavelengths

NASA Astrophysics Data System (ADS)

O'Brient, Roger; Ade, Peter; Arnold, Kam; Edwards, Jennifer; Engargiola, Greg; Holzapfel, William L.; Lee, Adrian T.; Myers, Michael J.; Quealy, Erin; Rebeiz, Gabriel; Richards, Paul; Suzuki, Aritoki

2013-02-01

We describe the design, fabrication, and testing of a broadband log-periodic antenna coupled to multiple cryogenic bolometers. This detector architecture, optimized here for astrophysical observations, simultaneously receives two linear polarizations with two octaves of bandwidth at millimeter wavelengths. The broad bandwidth signal received by the antenna is divided into sub-bands with integrated in-line frequency-selective filters. We demonstrate two such filter banks: a diplexer with two sub-bands and a log-periodic channelizer with seven contiguous sub-bands. These detectors have receiver efficiencies of 20%-40% and percent level polarization isolation. Superconducting transition-edge sensor bolometers detect the power in each sub-band and polarization. We demonstrate circularly symmetric beam patterns, high polarization isolation, accurately positioned bands, and high optical efficiency. The pixel design is applicable to astronomical observations of intensity and polarization at millimeter through sub-millimeter wavelengths. As compared with an imaging array of pixels measuring only one band, simultaneous measurements of multiple bands in each pixel has the potential to result in a higher signal-to-noise measurement while also providing spectral information. This development facilitates compact systems with high mapping speeds for observations that require information in multiple frequency bands.

Dense array recordings in the San Bernardino Valley of landers-big bear aftershocks: Basin surface waves, Moho reflections, and three-dimensional simulations

USGS Publications Warehouse

Frankel, Arthur

1994-01-01

Fourteen GEOS seismic recorders were deployed in the San Bernardino Valley to study the propagation of short-period (T ≈ 1 to 3 sec) surface waves and Moho reflections. Three dense arrays were used to determine the direction and speed of propagation of arrivals in the seismograms. The seismograms for a shallow (d ≈ 1 km) M 4.9 aftershock of the Big Bear earthquake exhibit a very long duration (60 sec) of sustained shaking at periods of about 2 sec. Array analysis indicates that these late arrivals are dominated by surface waves traveling in various directions across the Valley. Some energy is arriving from a direction 180° from the epicenter and was apparently reflected from the edge of the Valley opposite the source. A close-in aftershock (Δ = 25 km, depth = 7 km) displays substantial short-period surface waves at deep-soil sites. A three-dimensional (3D) finite difference simulation produces synthetic seismograms with durations similar to those of the observed records for this event, indicating the importance of S-wave to surface-wave conversion near the edge of the basin. Flat-layered models severely underpredict the duration and spectral amplification of this deep-soil site. I show an example where the coda wave amplitude ratio at 1 to 2 Hz between a deep-soil and a rock site does not equal the S-wave amplitude ratio, because of the presence of surface waves in the coda of the deep-soil site. For one of the events studied (Δ ≈ 90 km), there are sizable phases that are critically reflected from the Moho (PmP and SmS). At one of the rock sites, the SmS phase has a more peaked spectrum that the direct S wave.

Application of Immunosignatures for Diagnosis of Valley Fever

PubMed Central

Navalkar, Krupa Arun; Johnston, Stephen Albert; Woodbury, Neal; Galgiani, John N.; Magee, D. Mitchell; Chicacz, Zbigniew

2014-01-01

Valley fever (VF) is difficult to diagnose, partly because the symptoms of VF are confounded with those of other community-acquired pneumonias. Confirmatory diagnostics detect IgM and IgG antibodies against coccidioidal antigens via immunodiffusion (ID). The false-negative rate can be as high as 50% to 70%, with 5% of symptomatic patients never showing detectable antibody levels. In this study, we tested whether the immunosignature diagnostic can resolve VF false negatives. An immunosignature is the pattern of antibody binding to random-sequence peptides on a peptide microarray. A 10,000-peptide microarray was first used to determine whether valley fever patients can be distinguished from 3 other cohorts with similar infections. After determining the VF-specific peptides, a small 96-peptide diagnostic array was created and tested. The performances of the 10,000-peptide array and the 96-peptide diagnostic array were compared to that of the ID diagnostic standard. The 10,000-peptide microarray classified the VF samples from the other 3 infections with 98% accuracy. It also classified VF false-negative patients with 100% sensitivity in a blinded test set versus 28% sensitivity for ID. The immunosignature microarray has potential for simultaneously distinguishing valley fever patients from those with other fungal or bacterial infections. The same 10,000-peptide array can diagnose VF false-negative patients with 100% sensitivity. The smaller 96-peptide diagnostic array was less specific for diagnosing false negatives. We conclude that the performance of the immunosignature diagnostic exceeds that of the existing standard, and the immunosignature can distinguish related infections and might be used in lieu of existing diagnostics. PMID:24964807

Coherent Detector Arrays for Continuum and Spectral Line Applications

NASA Technical Reports Server (NTRS)

Gaier, Todd C.

2006-01-01

This viewgraph presentation reviews the requirements for improved coherent detector arrays for use in continuum and spectral line applications. With detectors approaching fundamental limits, large arrays offer the only path to sensitivity improvement. Monolithic Microwave Integrated Circuit (MMIC) technology offers a straightforward path to massive focal plane millimeter wave arrays: The technology will readily support continuum imagers, polarimeters and spectral line receivers from 30-110 GHz. Science programs, particularly large field blind surveys will benefit from simultaneous observations of hundreds or thousands of pixels 1000 element array is competitive with a cost less than $2M.

High-performance packaging for monolithic microwave and millimeter-wave integrated circuits

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Li, K.; Shih, Y. C.

1992-01-01

Packaging schemes are developed that provide low-loss, hermetic enclosure for enhanced monolithic microwave and millimeter-wave integrated circuits. These package schemes are based on a fused quartz substrate material offering improved RF performance through 44 GHz. The small size and weight of the packages make them useful for a number of applications, including phased array antenna systems. As part of the packaging effort, a test fixture was developed to interface the single chip packages to conventional laboratory instrumentation for characterization of the packaged devices.

Millimeter wave imaging: a historical review

NASA Astrophysics Data System (ADS)

Appleby, Roger; Robertson, Duncan A.; Wikner, David

2017-05-01

The SPIE Passive and Active Millimeter Wave Imaging conference has provided an annual focus and forum for practitioners in the field of millimeter wave imaging for the past two decades. To celebrate the conference's twentieth anniversary we present a historical review of the evolution of millimeter wave imaging over the past twenty years. Advances in device technology play a fundamental role in imaging capability whilst system architectures have also evolved. Imaging phenomenology continues to be a crucial topic underpinning the deployment of millimeter wave imaging in diverse applications such as security, remote sensing, non-destructive testing and synthetic vision.

High-performance packaging for monolithic microwave and millimeter-wave integrated circuits

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Li, K.; Shih, Y. C.

1992-01-01

Packaging schemes were developed that provide low-loss, hermetic enclosure for advanced monolithic microwave and millimeter-wave integrated circuits (MMICs). The package designs are based on a fused quartz substrate material that offers improved radio frequency (RF) performance through 44 gigahertz (GHz). The small size and weight of the packages make them appropriate for a variety of applications, including phased array antenna systems. Packages were designed in two forms; one for housing a single MMIC chip, the second in the form of a multi-chip phased array module. The single chip array module was developed in three separate sizes, for chips of different geometry and frequency requirements. The phased array module was developed to address packaging directly for antenna applications, and includes transmission line and interconnect structures to support multi-element operation. All packages are fabricated using fused quartz substrate materials. As part of the packaging effort, a test fixture was developed to interface the single chip packages to conventional laboratory instrumentation for characterization of the packaged devices. The package and test fixture designs were both developed in a generic sense, optimizing performance for a wide range of possible applications and devices.

Extended Millimeter Emission in the HD 141569 Circumstellar Disk Detected with ALMA

NASA Astrophysics Data System (ADS)

White, Jacob Aaron; Boley, A. C.

2018-06-01

We present archival Atacama Large Millimeter/submillimeter Array (ALMA) observations of the HD 141569 circumstellar disk at 345, 230, and 100 GHz. These data detect extended millimeter emission that is exterior to the inner disk. We find through simultaneous visibility modeling of all three data sets that the system’s morphology is described well by a two-component disk model. The inner disk ranges from approximately 16–45 au with a spectral index of 1.81 (q = 2.95), and the outer disk ranges from 95 to 300 au with a spectral index of 2.28 (q = 3.21). Azimuthally averaged radial emission profiles derived from the continuum images at each frequency show potential emission that is consistent with the visibility modeling. The analysis presented here shows that at ∼5 Myr, HD 141569's grain size distribution is steeper and therefore possibly evolved in the outer disk than in the inner disk.

Millimeter and hard x ray/gamma ray observations of solar flares during the June 1991 GRO campaign

NASA Technical Reports Server (NTRS)

Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J.

1992-01-01

We have carried out high-spatial-resolution millimeter observations of solar flares using the Berkeley-Illinois-Maryland Array (BIMA). At the present time, BIMA consists of only three elements, which is not adequate for mapping highly variable solar phenomena, but is excellent for studies of the temporal structure of flares at millimeter wavelengths at several different spatial scales. We present BIMA observations made during the Gamma Ray Observatories (GRO)/Solar Max 1991 campaign in Jun. 1991 when solar activity was unusually high. Our observations covered the period 8-9 Jun. 1991; this period overlapped the period 4-15 Jun. when the Compton Telescope made the Sun a target of opportunity because of the high level of solar activity.

Fabrication of an Absorber-Coupled MKID Detector and Readout for Sub-Millimeter and Far-Infrared Astronomy

NASA Technical Reports Server (NTRS)

Brown, Ari-David; Hsieh, Wen-Ting; Moseley, S. Harvey; Stevenson, Thomas R.; U-yen, Kongpop; Wollack, Edward J.

2010-01-01

We have fabricated absorber-coupled microwave kinetic inductance detector (MKID) arrays for sub-millimeter and far-infrared astronomy. Each detector array is comprised of lambda/2 stepped impedance resonators, a 1.5 micrometer thick silicon membrane, and 380 micrometer thick silicon walls. The resonators consist of parallel plate aluminum transmission lines coupled to low impedance Nb microstrip traces of variable length, which set the resonant frequency of each resonator. This allows for multiplexed microwave readout and, consequently, good spatial discrimination between pixels in the array. The Al transmission lines simultaneously act to absorb optical power and are designed to have a surface impedance and filling fraction so as to match the impedance of free space. Our novel fabrication techniques demonstrate high fabrication yield of MKID arrays on large single crystal membranes and sub-micron front-to-back alignment of the microstrip circuit.

Fabrication of an Absorber-Coupled MKID Detector and Readout for Sub-Millimeter and Far-Infrared Astronomy

NASA Technical Reports Server (NTRS)

Brown, Ari-David; Hsieh, Wen-Ting; Moseley, S. Harvey; Stevenson, Thomas R.; U-yen, Kongpop; Wollack, Edward J.

2010-01-01

We have fabricated absorber-coupled microwave kinetic inductance detector (MKID) arrays for sub-millimeter and farinfrared astronomy. Each detector array is comprised of lambda/2 stepped impedance resonators, a 1.5µm thick silicon membrane, and 380µm thick silicon walls. The resonators consist of parallel plate aluminum transmission lines coupled to low impedance Nb microstrip traces of variable length, which set the resonant frequency of each resonator. This allows for multiplexed microwave readout and, consequently, good spatial discrimination between pixels in the array. The Al transmission lines simultaneously act to absorb optical power and are designed to have a surface impedance and filling fraction so as to match the impedance of free space. Our novel fabrication techniques demonstrate high fabrication yield of MKID arrays on large single crystal membranes and sub-micron front-to-back alignment of the microstrip circuit.

Full-Sky Maps of the VHF Radio Sky with the Owens Valley Radio Observatory Long Wavelength Array

NASA Astrophysics Data System (ADS)

Eastwood, Michael W.; Hallinan, Gregg

2018-05-01

21-cm cosmology is a powerful new probe of the intergalactic medium at redshifts 20 >~ z >~ 6 corresponding to the Cosmic Dawn and Epoch of Reionization. Current observations of the highly-redshifted 21-cm transition are limited by the dynamic range they can achieve against foreground sources of low-frequency (<200 MHz) of radio emission. We used the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) to generate a series of new modern high-fidelity sky maps that capture emission on angular scales ranging from tens of degrees to ~15 arcmin, and frequencies between 36 and 73 MHz. These sky maps were generated from the application of Tikhonov-regularized m-mode analysis imaging, which is a new interferometric imaging technique that is uniquely suited for low-frequency, wide-field, drift-scanning interferometers.

Compressive passive millimeter wave imager

DOEpatents

Gopalsami, Nachappa; Liao, Shaolin; Elmer, Thomas W; Koehl, Eugene R; Heifetz, Alexander; Raptis, Apostolos C

2015-01-27

A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is positioned to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

Advances in real-time millimeter-wave imaging radiometers for avionic synthetic vision

NASA Astrophysics Data System (ADS)

Lovberg, John A.; Chou, Ri-Chee; Martin, Christopher A.; Galliano, Joseph A., Jr.

1995-06-01

Millimeter-wave imaging has advantages over conventional visible or infrared imaging for many applications because millimeter-wave signals can travel through fog, snow, dust, and clouds with much less attenuation than infrared or visible light waves. Additionally, passive imaging systems avoid many problems associated with active radar imaging systems, such as radar clutter, glint, and multi-path return. ThermoTrex Corporation previously reported on its development of a passive imaging radiometer that uses an array of frequency-scanned antennas coupled to a multichannel acousto-optic spectrum analyzer (Bragg-cell) to form visible images of a scene through the acquisition of thermal blackbody radiation in the millimeter-wave spectrum. The output from the Bragg cell is imaged by a standard video camera and passed to a computer for normalization and display at real-time frame rates. An application of this system is its incorporation as part of an enhanced vision system to provide pilots with a synthetic view of a runway in fog and during other adverse weather conditions. Ongoing improvements to a 94 GHz imaging system and examples of recent images taken with this system will be presented. Additionally, the development of dielectric antennas and an electro- optic-based processor for improved system performance, and the development of an `ultra- compact' 220 GHz imaging system will be discussed.

Alumina+Silica+/-Germanium Alteration in Smectite-Bearing Marathon Valley, Endeavour Crater Rim, Mars

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Gellert, R.; Van Bommel, S.; Arvidson, R. E.; Clark, B. C.; Ming, D. W.; Schroeder, C.; Yen, A. S.; Fox, V. K.; Farrand, W. H.;

Sub-millimeter wave frequency heterodyne detector system

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

2009-01-01

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Sub-millimeter wave frequency heterodyne detector system

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

2010-01-01

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Antenna-Coupled Bolometer Arrays for Astrophysics

NASA Astrophysics Data System (ADS)

Bock, James

Bolometers offer the best sensitivity in the far-infrared to millimeter-wave region of the electromagnetic spectrum. We are developing arrays of feedhorn-coupled bolometers for the ESA/NASA Planck Surveyor and Herschel Space Observatory. Advances in the format and sensitivity of bolometric focal plane array enables future astrophysics mission opportunities, such as CMB polarimetry and far-infrared/submillimeter spectral line surveys. Compared to bolometers with extended area radiation absorbers, antenna-coupled bolometers offer active volumes that are orders of magnitude smaller. Coupled to lithographed micro-strip filters and antennas, antenna-coupled bolometer arrays allow flexible focal plane architectures specialized for imaging, polarimetry, and spectroscopy. These architectures greatly reduce the mass of sub-Kelvin bolometer focal planes that drive the design of bolometric instrumentation.

Preliminary estimates of spatially distributed net infiltration and recharge for the Death Valley region, Nevada-California

USGS Publications Warehouse

Hevesi, J.A.; Flint, A.L.; Flint, L.E.

2002-01-01

A three-dimensional ground-water flow model has been developed to evaluate the Death Valley regional flow system, which includes ground water beneath the Nevada Test Site. Estimates of spatially distributed net infiltration and recharge are needed to define upper boundary conditions. This study presents a preliminary application of a conceptual and numerical model of net infiltration. The model was developed in studies at Yucca Mountain, Nevada, which is located in the approximate center of the Death Valley ground-water flow system. The conceptual model describes the effects of precipitation, runoff, evapotranspiration, and redistribution of water in the shallow unsaturated zone on predicted rates of net infiltration; precipitation and soil depth are the two most significant variables. The conceptual model was tested using a preliminary numerical model based on energy- and water-balance calculations. Daily precipitation for 1980 through 1995, averaging 202 millimeters per year over the 39,556 square kilometers area of the ground-water flow model, was input to the numerical model to simulate net infiltration ranging from zero for a soil thickness greater than 6 meters to over 350 millimeters per year for thin soils at high elevations in the Spring Mountains overlying permeable bedrock. Estimated average net infiltration over the entire ground-water flow model domain is 7.8 millimeters per year.To evaluate the application of the net-infiltration model developed on a local scale at Yucca Mountain, to net-infiltration estimates representing the magnitude and distribution of recharge on a regional scale, the net-infiltration results were compared with recharge estimates obtained using empirical methods. Comparison of model results with previous estimates of basinwide recharge suggests that the net-infiltration estimates obtained using this model may overestimate recharge because of uncertainty in modeled precipitation, bedrock permeability, and soil properties for

Millimeter and Submillimeter Wave Spectroscopy of Higher Energy Conformers of 1,2-PROPANEDIOL

NASA Astrophysics Data System (ADS)

Zakharenko, Olena; Bossa, Jean-Baptiste; Lewen, Frank; Schlemmer, Stephan; Müller, Holger S. P.

2017-06-01

We have performed a study of the millimeter/submillimeter wave spectrum of four higher energy conformers of 1,2-propanediol (continuation of the previous study on the three lowest energy conformers. The present analysis of rotational transitions carried out in the frequency range 38 - 400 GHz represents a significant extension of previous microwave work. The new data were combined with previously-measured microwave transitions and fitted using a Watson's S-reduced Hamiltonian. The final fits were within experimental accuracy, and included spectroscopic parameters up to sixth order of angular momentum, for the ground states of the four higher energy conformers following previously studied ones: g'Ga, gG'g', aGg' and g'Gg. The present analysis provides reliable frequency predictions for astrophysical detection of 1,2-propanediol by radio telescope arrays at millimeter wavelengths. J.-B. Bossa, M.H. Ordu, H.S.P. Müller, F. Lewen, S. Schlemmer, A&A 570 (2014) A12)

Compact Radiative Control Structures for Millimeter Astronomy

NASA Technical Reports Server (NTRS)

Brown, Ari D.; Chuss, David T.; Chervenak, James A.; Henry, Ross M.; Moseley, s. Harvey; Wollack, Edward J.

2010-01-01

We have designed, fabricated, and tested compact radiative control structures, including antireflection coatings and resonant absorbers, for millimeter through submillimeter wave astronomy. The antireflection coatings consist of micromachined single crystal silicon dielectric sub-wavelength honeycombs. The effective dielectric constant of the structures is set by the honeycomb cell geometry. The resonant absorbers consist of pieces of solid single crystal silicon substrate and thin phosphorus implanted regions whose sheet resistance is tailored to maximize absorption by the structure. We present an implantation model that can be used to predict the ion energy and dose required for obtaining a target implant layer sheet resistance. A neutral density filter, a hybrid of a silicon dielectric honeycomb with an implanted region, has also been fabricated with this basic approach. These radiative control structures are scalable and compatible for use large focal plane detector arrays.

Millimeter Wave Radar Applications to Weapons Systems

DTIC Science & Technology

1976-06-01

meter wave region compared with the high attenuation in the optical region. It is this unique characteristic of millimeter waves to penetrate fog...miiliaeter wave radars in graund-to-- air , ground-to-ground, and air -to-ground weapons systems aye presented. The advantages and limitation~s¶ of operating...MILLIMETER WAVE RADAR CHARACTERISTICS ..... ............ .. 27 A, General ................ ......................... ... 27 B. Ground-to- Air Millimeter

Investigation of radiant millimeter wave/terahertz radiation from low-infrared signature targets

NASA Astrophysics Data System (ADS)

Aytaç, B.; Alkuş, Ü.; Sivaslıgil, M.; Şahin, A. B.; Altan, H.

2017-10-01

Millimeter (mm) and sub-mm wave radiation is increasingly becoming a region of interest as better methods are developed to detect in this wavelength range. The development of sensitive focal plane array (FPA) architectures as well as single pixel scanners has opened up a new field of passive detection and imaging. Spectral signatures of objects, a long standing area of interest in the Short Wave Infrared (SWIR), Mid-Wave (MWIR) and Long Wave-IR (LWIR) bands can now be assessed in the mm-wave/terahertz (THz) region. The advantage is that this form of radiation is not as adversely affected by poor atmospheric conditions compared to other bands. In this study, a preliminary experiment in a laboratory environment is performed to assess the radiance from targets with low infrared signatures in the millimeter wave/terahertz (THz) band (<1 THz). The goal of this approach is to be able to model the experimental results to better understand the mm-wave/THz signature of targets with low observability in the IR bands.

Slotted Polyimide-Aerogel-Filled-Waveguide Arrays

NASA Technical Reports Server (NTRS)

Rodriguez-Solis, Rafael A.; Pacheco, Hector L.; Miranda, Felix A.; Meador, Mary Ann B.

2013-01-01

Polyimide aerogels were considered to serve as a filling for millimeter-wave waveguides. While these waveguides present a slightly higher loss than hollow waveguides, they have less losses than Duroid substrate integrated waveguides (less than 0.15 dB at Ka-band, in a 20 mm section), and exhibit an order of magnitude of mass reduction when compared to commercial waveguides. A Ka-band slotted aerogel-filled-waveguide array was designed, which provided the same gain (9 dBi) as its standard waveguide counterpart, and a slotted aerogel-filled-waveguide array using folded-slots was designed for comparison, obtaining a gain of 9 dB and a bandwidth of 590 MHz.

Graphene array antenna for 5G applications

NASA Astrophysics Data System (ADS)

Sa'don, Siti Nor Hafizah; Kamarudin, Muhammad Ramlee; Ahmad, Fauzan; Jusoh, Muzammil; Majid, Huda A.

2017-02-01

Fifth generation (5G) needs to provide better coverage than the previous generation. However, high frequency and millimeter wave experience penetration loss, propagation loss and even more loss in energy for long distance. Hence, a graphene array antenna is proposed for high gain to cover a long distance communications since array antenna enables in providing more directive beams. The investigation is conducted on three types of substrates with gain achieved is more than 7 dBi. The gain obtained is good since it is comparable with other studies. In addition, these antennas consume small numbers of elements to achieve high gain.

Instrument Performance of GISMO, a 2 Millimeter TES Bolometer Camera used at the IRAM 30 m Telescope

NASA Technical Reports Server (NTRS)

Staguhn, Johannes

2008-01-01

In November of 2007 we demonstrated a monolithic Backshort-Under-Grid (BUG) 8x16 array in the field using our 2 mm wavelength imager GISMO (Goddard IRAM Superconducting 2 Millimeter Observer) at the IRAM 30 m telescope in Spain for astronomical observations. The 2 mm spectral range provides a unique terrestrial window enabling ground-based observations of the earliest active dusty galaxies in the universe and thereby allowing a better constraint on the star formation rate in these objects. The optical design incorporates a 100 mm diameter silicon lens cooled to 4 K, which provides the required fast beam yielding 0.9 lambda/D pixels. With this spatial sampling, GISMO will be very efficient at detecting sources serendipitously in large sky surveys, while the capability for diffraction limited imaging is preserved. The camera provides significantly greater detection sensitivity and mapping speed at this wavelength than has previously been possible. The instrument will fill in the spectral energy distribution of high redshift galaxies at the Rayleigh-Jeans part of the dust emission spectrum, even at the highest redshifts. Here1 will we present early results from our observing run with the first fielded BUG bolometer array. We have developed key technologies to enable highly versatile, kilopixel, infrared through millimeter wavelength bolometer arrays. The Backshort-Under-Grid (BUG) array consists of three components: 1) a transition-edge-sensor (TES) based bolometer array with background-limited sensitivity and high filling factor, 2) a quarter-wave reflective backshort grid providing high optical efficiency, and 3) a superconducting bump-bonded large format Superconducting Quantum Interference Device (SQUID) multiplexer readout. The array is described in more detail elsewhere (Allen et al., this conference). In November of 2007 we demonstrated a monolithic 8x 16 array with 2 mm-pitch detectors in the field using our 2 mm wavelength imager GISMO (Goddard IRAM

Morning Transition Tracer Experiments in a Deep Narrow Valley.

NASA Astrophysics Data System (ADS)

Whiteman, C. David

1989-07-01

Three sulfur hexafluoride atmospheric tracer experiments were conducted during the post-sunrise temperature inversion breakup period in the deep, narrow Brush Creek Valley of Colorado. Experiments were conducted under clear, undisturbed weather conditions.A continuous elevated tracer plume was produced along the axis of the valley before sunrise and the behavior of the plume during the inversion breakup period was detected down-valley from the release point using an array of radio-controlled sequential bag samplers, a vertical SF6 profiling system carried on a tethered balloon, two portable gas chromatographs operated on a sidewall of the valley, and a continuous real-time SF6 monitor operated from a research aircraft. Supporting meteorological data came primarily from tethered balloon profilers. The nocturnal elevated plume was carried and diffused in down-valley flows. After sunrise, convective boundary layers grew upward from the sunlit valley surfaces, fumigating the elevated plume onto the valley floor and sidewalls. Upslope flow developed in the growing convective boundary layers, carrying fumigated SF6 up the sidewalls and causing a compensating subsidence over the valley center. High post-sunrise SF6 concentrations were experienced on the northeast-facing sidewall of the northwest-southeast oriented valley as a result of cross-valley flow, which developed due to differential solar heating of the sidewalls. Reversal of the down-valley wind system brought air with lower SF6 concentrations into the lower valley.

Formation, Detection and the Distribution of Complex Organic Molecules with the Atacama Large Millimeter/submillimeter Array (ALMA)

NASA Astrophysics Data System (ADS)

Remijan, Anthony John

2015-08-01

The formation and distribution of complex organic material in astronomical environments continues to be a focused research area in astrochemistry. For several decades now, emphasis has been placed on the millimeter/submillimeter regime of the radio spectrum for trying to detect new molecular species and to constrain the chemical formation route of complex molecules by comparing and contrasting their relative distributions towards varying astronomical environments. This effort has been extremely laborious as millimeter/submillimeter facilities have been only able to detect and map the distribution of the strongest transition(s) of the simplest organic molecules. Even then, these single transition "chemical maps" have been very low spatial resolution because early millimeter/submillimeter facilities did not have access to broadband spectral coverage or the imaging capabilities to truly ascertain the morphology of the molecular emission. In the era of ALMA, these limitations have been greatly lifted. Broadband spectral line surveys now hold the key to uncovering the full molecular complexity in astronomical environments. In addition, searches for complex organic material is no longer limited to investigating the strongest lines of the simplest molecules toward the strongest sources of emission in the Galaxy. ALMA is issuing a new era of exploration as the search for complex molecules will now be available to an increased suite of sources in the Galaxy and our understanding of the formation of this complex material will be greatly increased as a result. This presentation will highlight the current and future ALMA capabilities in the search for complex molecules towards astronomical environments, highlight the recent searches that ALMA scientists have conducted from the start of ALMA Early Science and provide the motivation for the next suite of astronomical searches to investigate our pre-biotic origins in the universe.

Ssalmon - The Solar Simulations For The Atacama Large Millimeter Observatory Network

NASA Astrophysics Data System (ADS)

Wedemeyer, Sven; Ssalmon Group

2016-07-01

The Atacama Large Millimeter/submillimeter Array (ALMA) provides a new powerful tool for observing the solar chromosphere at high spatial, temporal, and spectral resolution, which will allow for addressing a wide range of scientific topics in solar physics. Numerical simulations of the solar atmosphere and modeling of instrumental effects are valuable tools for constraining, preparing and optimizing future observations with ALMA and for interpreting the results. In order to co-ordinate related activities, the Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) was initiated on September 1st, 2014, in connection with the NA- and EU-led solar ALMA development studies. As of April, 2015, SSALMON has grown to 83 members from 18 countries (plus ESO and ESA). Another important goal of SSALMON is to promote the scientific potential of solar science with ALMA, which has resulted in two major publications so far. During 2015, the SSALMON Expert Teams produced a White Paper with potential science cases for Cycle 4, which will be the first time regular solar observations will be carried out. Registration and more information at http://www.ssalmon.uio.no.

Research Spotlight: Groundwater is being depleted rapidly in California's Central Valley

NASA Astrophysics Data System (ADS)

Tretkoff, Ernie

2011-03-01

Groundwater is being depleted in California's Central Valley at a rapid rate, according to data from the Gravity Recovery and Climate Experiment (GRACE) satellite. Famiglietti et al. analyzed 78 months of GRACE data covering October 2003 to March 2010 to estimate water storage changes in California's Sacramento and San Joaquin river basins. They found that the basins are losing water at a rate of about 30 millimeters per year equivalent water height, or a total of about 30 cubic kilometers over the 78-month period. Furthermore, they found that two thirds of this loss, or a total of 20 cubic kilometers for the study period, came from groundwater depletion in the Central Valley. Quantifying groundwater depletion can be challenging in many areas because of a lack of monitoring infrastructure and reporting requirements; the study shows that satellite-based monitoring can be a useful way to track groundwater volumes. The authors warn that the current rate of groundwater depletion in the Central Valley may be unsustainable and could have “potentially dire consequences for the economic and food security of the United States.” (Geophysical Research Letters, doi:10.1029/2010GL046442, 2011)

Dense arrays of millimeter-sized glass lenses fabricated at wafer-level.

PubMed

Albero, Jorge; Perrin, Stéphane; Bargiel, Sylwester; Passilly, Nicolas; Baranski, Maciej; Gauthier-Manuel, Ludovic; Bernard, Florent; Lullin, Justine; Froehly, Luc; Krauter, Johann; Osten, Wolfgang; Gorecki, Christophe

2015-05-04

This paper presents the study of a fabrication technique of lenses arrays based on the reflow of glass inside cylindrical silicon cavities. Lenses whose sizes are out of the microfabrication standards are considered. In particular, the case of high fill factor arrays is discussed in detail since the proximity between lenses generates undesired effects. These effects, not experienced when lenses are sufficiently separated so that they can be considered as single items, are corrected by properly designing the silicon cavities. Complete topographic as well as optical characterizations are reported. The compatibility of materials with Micro-Opto-Electromechanical Systems (MOEMS) integration processes makes this technology attractive for the miniaturization of inspection systems, especially those devoted to imaging.

Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation

PubMed Central

Ibrahim, Akram; Férachou, Denis; Sharma, Gargi; Singh, Kanwarpal; Kirouac-Turmel, Marie; Ozaki, Tsuneyuki

2016-01-01

Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 106, which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results. PMID:26976363

Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation.

PubMed

Ibrahim, Akram; Férachou, Denis; Sharma, Gargi; Singh, Kanwarpal; Kirouac-Turmel, Marie; Ozaki, Tsuneyuki

2016-03-15

Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 10(6), which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results.

Millimeter Wave Communication through Plasma

NASA Technical Reports Server (NTRS)

Bastin, Gary L.

2008-01-01

Millimeter wave communication through plasma at frequencies of 35 GHz or higher shows promise in maintaining communications connectivity during rocket launch and re-entry, critical events which are typically plagued with communication dropouts. Extensive prior research into plasmas has characterized the plasma frequency at these events, and research at the Kennedy Space Center is investigating the feasibility of millimeter communication through these plasma frequencies.

Millimeter and submillimeter observations from the Atacama plateau and high altitude balloons

NASA Astrophysics Data System (ADS)

Devlin, Mark

2002-05-01

A new generation of ground-based and sub-orbital platforms will be operational in the next few years. These telescopes will operate from high sites in Chile and Antarctica, and airborne platforms where the atmosphere is transparent enough to allow sensitive measurements in the millimeter and submillimeter bands. The telescopes will employ state-of-the-art instrumentation including large format bolometer arrays and spectrometers. I will discuss the results of our observations in the Atacama region of Chile (MAT/TOCO), our future observations on the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) now under construction, and our proposed Atacama Cosmology Telescope (ACT). .

Infrasound and seismic array analysis of snow avalanches: results from the 2015-2017 experiment in Dischma valley above Davos, Switzerland

NASA Astrophysics Data System (ADS)

Marchetti, Emanuele; van Herwijnen, Alec; Ripepe, Maurizio

2017-04-01

While flowing downhill a snow avalanche radiates seismic and infrasonic waves being coupled both with the ground and the atmosphere. Infrasound waves are mostly generated by the powder cloud of the avalanche, while seismic waves are mostly generated by the dense flowing snow mass on the ground, resulting in different energy partitioning between seismic and infrasound for different kinds of avalanches. This results into a general uncertainty on the efficiency of seismic and infrasound monitoring, in terms of the size and source-to-receiver distance of detectable events. Nevertheless, both seismic and infrasound have been used as monitoring systems for the remote detection of snow avalanches, being the reliable detection of snow avalanches of crucial importance to better understand triggering mechanisms, identify possible precursors, or improve avalanche forecasting. We present infrasonic and seismic array data collected during the winters of 2015- 2016 and 2016-2017 in the Dischma valley above Davos, Switzerland, where a five element infrasound array and a 7 element seismic array had been deployed at short distance from each other and with several avalanche paths nearby. Avalanche observation in the area is performed through automatic cameras providing additional information on the location, type (dry or wet), size and occurrence time of the avalanches released. The use of arrays instead of single sensors allows increasing the signal-to-noise ratio and identifying events in terms of back-azimuth and apparent velocity of the wave-field, thus providing indication on the source position of the recorded signal. For selected snow avalanches captured with automatic cameras, we therefore perform seismic and infrasound array processing to constrain the avalanche path and dynamics and investigate the partitioning of seismic and infrasound energy for the different portions of the avalanche path. Moreover we compare results of seismic and infrasound array processing for the

DIRECT DETECTION OF PRECURSORS OF GAS GIANTS FORMED BY GRAVITATIONAL INSTABILITY WITH THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayer, Lucio; Peters, Thomas; Pineda, Jaime E.

Phases of gravitational instability are expected in the early phases of disk evolution, when the disk mass is still a substantial fraction of the mass of the star. Disk fragmentation into sub-stellar objects could occur in the cold exterior part of the disk. Direct detection of massive gaseous clumps on their way to collapse into gas giant planets would offer an unprecedented test of the disk instability model. Here we use state-of-the-art 3D radiation-hydro simulations of disks undergoing fragmentation into massive gas giants, post-processed with RADMC-3D to produce dust continuum emission maps. These are then fed into the Common Astronomymore » Software Applications (CASA) ALMA simulator. The synthetic maps show that both overdense spiral arms and actual clumps at different stages of collapse can be detected with the Atacama Large Millimeter/submillimeter Array (ALMA) in the full configuration at the distance of the Ophiuchus star forming region (125 pc). The detection of clumps is particularly effective at shorter wavelengths (690 GHz) combining two resolutions with multi-scale clean. Furthermore, we show that a flux-based estimate of the mass of a protoplanetary clump can be comparable to a factor of three higher than the gravitationally bound clump mass. The estimated mass depends on the assumed opacity, and on the gas temperature, which should be set using the input of radiation-hydro simulations. We conclude that ALMA has the capability to detect “smoking gun” systems that are a signpost of the disk instability model for gas giant planet formation.« less

The Millimeter Sky Transparency Imager (MiSTI)

NASA Astrophysics Data System (ADS)

Tamura, Yoichi; Kawabe, Ryohei; Kohno, Kotaro; Fukuhara, Masayuki; Momose, Munetake; Ezawa, Hajime; Kuboi, Akihito; Sekiguchi, Tomohiko; Kamazaki, Takeshi; Vila-Vilaró, Baltasar; Nakagawa, Yuki; Okada, Norio

2011-04-01

The Millimeter Sky Transparency Imager (MiSTI) is a small millimeter-wave scanning telescope with a 25-cm diameter dish operating at 183 GHz. MiSTI is installed at Atacama, Chile, and it measures emission from atmospheric water vapor and its fluctuations to estimate atmospheric absorption in the millimeter to submillimeter range. MiSTI observes the water vapor distribution at a spatial resolution of 0.°5, and it is sensitive enough to detect an excess path length of lesssim0.05 mm for an integration time of 1 s. By comparing the MiSTI measurements with those by a 220 GHz tipper, we validated that the 183 GHz measurements of MiSTI are correct, down to the level of any residual systematic errors in the 220 GHz measurements. Since 2008, MiSTI has provided real-time (every 1 hr) monitoring of the all-sky opacity distribution and atmospheric transmission curves in the (sub)millimeter through the internet, allowing us to know the (sub)millimeter sky conditions at Atacama.

Development of adaptive liquid microlenses and microlens arrays

NASA Astrophysics Data System (ADS)

Berry, Shaun R.; Stewart, Jason B.; Thorsen, Todd A.; Guha, Ingrid

2013-03-01

We report on the development of sub-millimeter size adaptive liquid microlenses and microlens arrays using two immiscible liquids to form individual lenses. Microlenses and microlens arrays having aperture diameters as small as 50 microns were fabricated on a planar quartz substrate using patterned hydrophobic/hydrophilic regions. Liquid lenses were formed by a self-assembled oil dosing process that created well-defined lenses having a high fill factor. Variable focus was achieved by controlling the lens curvature through electrowetting. Greater than 70° of contact angle change was achieved with less than 20 volts, which results in a large optical power dynamic range.

A reinterpretation of millimeter observations of nearby IRAS excess stars

NASA Technical Reports Server (NTRS)

Weintraub, David A.; Stern, S. Alan

1994-01-01

We analyze new and previously published 1300, 870, and 800 micrometers, single-element bolometer observations of Vega (alpha Lyr), Formalhaut (alpha PsA), epsilon Eri, tau(sup1) Eri, and Beta Leo. We show that these data are consistent with models in which the dust disks around these stars are larger than the radio telescope beams with which they were observed; thus, these disks may be many hundreds of AU in radius or larger. Our interpretation of submillimeter/millimeter measurements of these stars also indicates that for some Infrared Astronomy Satellite (IRAS) IR excess stars the assumption that there is no astrophysical flux in the OFF beams, when using the standard ON-minus-OFF chopping technique and the chop distance is less than 1000AU, may be incorrect. Therefore, for IRAS IR excess stars within approximately 20 pc, virtually all submillimeter/millimeter chopping observations with chop throws less than 100" may have subtracted away some or most of the flux associated with their circumstellar disks. Finally, we present new 1300 micrometers continuum observations of Vega made with chop throws of 500 and 1000 AU. These data are consistent with an interpretation in which Vega has a disk that is at least 1000AU in radius; this disk could have a region with much less material per beam area near 500 AU than at both 100 AU and 1000 AU, corresponding to a gap at the orbital distance of alpha Lyr B. The observations of Vega are also consistent with the assumption that the circumVega dust structure is unresolved. Thus, these new data very effectively illustrate that the 'standard' model of small, unresolved, dust structures around main-sequence IRAS IR excess stars is not unique. Maps of IRAS IR excess stars, which soon will be available from submillimeter/millimeter array detectors, will determine whether the paradigm shift we propose will occur.

A sub-millimeter resolution detector module for small-animal PET applications

NASA Astrophysics Data System (ADS)

Sacco, I.; Dohle, R.; Fischer, P.; Gola, A.; Piemonte, C.; Ritzert, M.

2017-01-01

We present a gamma detection module optimized for very high resolution PET applications, able to resolve arrays of scintillating crystals with sub-millimeter pitch. The detector is composed of a single ceramic substrate (LTCC): it hosts four flip-chip mounted PETA5 ASICs on the bottom side and an array of SiPM sensors on the top surface, fabricated in HD-RGB technology by FBK. Each chip has 36 channels, for a maximum of 144 readout channels on a sensitive area of about 32 mm × 32 mm. The module is MR-compatible. The thermal decoupling of the readout electronics from the photon sensors is obtained with an efficient internal liquid channel, integrated within the ceramic substrate. Two modules have been designed, based on different SiPM topologies: • Light spreader-based: an array of 12 × 12 SiPMs, with an overall pitch of 2.5 mm, is coupled with a scintillators array using a 1 mm thick glass plate. The light from one crystal is spread over a group of SiPMs, which are read out in parallel using PETA5 internal neighbor logic. • Interpolating SiPM-based: ISiPMs are intrinsic position-sensitive sensors. The photon diodes in the array are connected to one of the four available outputs so that the center of gravity of any bunch of detected photons can be reconstructed using a proper weight function of the read out amplitudes. An array of ISiPMs, each 7.5 mm× 5 mm sized, is directly coupled with the scintillating crystals. Both modules can clearly resolve LYSO arrays with a pitch of only 0.833 mm. The detector can be adjusted for clinical PET, where it has already shown ToF resolution of about 230 ps CRT at FWHM. The module designs, their features and results are described.

Millimeter wave satellite concepts, volume 1

NASA Technical Reports Server (NTRS)

Hilsen, N. B.; Holland, L. D.; Thomas, R. E.; Wallace, R. W.; Gallagher, J. G.

1977-01-01

The identification of technologies necessary for development of millimeter spectrum communication satellites was examined from a system point of view. Development of methodology based on the technical requirements of potential services that might be assigned to millimeter wave bands for identifying the viable and appropriate technologies for future NASA millimeter research and development programs, and testing of this methodology with selected user applications and services were the goals of the program. The entire communications network, both ground and space subsystems was studied. Cost, weight, and performance models for the subsystems, conceptual design for point-to-point and broadcast communications satellites, and analytic relationships between subsystem parameters and an overall link performance are discussed along with baseline conceptual systems, sensitivity studies, model adjustment analyses, identification of critical technologies and their risks, and brief research and development program scenarios for the technologies judged to be moderate or extensive risks. Identification of technologies for millimeter satellite communication systems, and assessment of the relative risks of these technologies, was accomplished through subsystem modeling and link optimization for both point-to-point and broadcast applications.

Quasi-optical antenna-mixer-array design for terahertz frequencies

NASA Technical Reports Server (NTRS)

Guo, Yong; Potter, Kent A.; Rutledge, David B.

1992-01-01

A new quasi-optical antenna-mixer-array design for terahertz frequencies is presented. In the design, antenna and mixer are combined into an entity, based on the technology in which millimeter-wave horn antenna arrays have been fabricated in silicon wafers. It consists of a set of forward- and backward-looking horns made with a set of silicon wafers. The front side is used to receive incoming signal, and the back side is used to feed local oscillator signal. Intermediate frequency is led out from the side of the array. Signal received by the horn array is picked up by antenna probes suspended on thin silicon-oxynitride membranes inside the horns. Mixer diodes will be located on the membranes inside the horns. Modeling of such an antenna-mixer-array design is done on a scaled model at microwave frequencies. The impedance matching, RF and LO isolation, and patterns of the array have been tested and analyzed.

Properties of Noise Cross Correlation Functions Obtained from a Distributed Acoustic Sensing (DAS) Array at Garner Valley, California

NASA Astrophysics Data System (ADS)

Zeng, X.; Lancelle, C.; Thurber, C. H.; Fratta, D.; Wang, H. F.; Chalari, A.; Clarke, A.

2015-12-01

The field test of Distributed Acoustic Sensing (DAS) conducted at Garner Valley, California on September 11-12, 2013 provided a continuous overnight record of ambient noise. The DAS array recorded ground motions every one meter of optical cable that was arranged approximately in the shape of a rectangle with dimensions of 160 m by 80 m. The long dimension of the array was adjacent to a state highway. Three hours of record were used to compute noise cross-correlation functions (NCFs) in one-minute windows. The trace from each sensor channel was pre-processed by downsampling to 200 Hz, followed by normalization in the time-domain and bandpass filtering between 2 and 20 Hz (Bensen et al., 2007). The one-minute NCFs were then stacked using the time-frequency domain phase-weighted stacking method (Schimmel & Gallart, 2007). The NCFs between channels were asymmetrical reflecting the direction of traffic noise. The group velocities were found using the frequency-time analysis method. The energy was concentrated between 5 and 15 Hz, which falls into the typical traffic noise frequency band. The resulting velocities were between 100 and 300 m/s for frequencies between 10 and 20 Hz, which are in the same range as described in the results for surface-wave dispersion obtained using an active source for the same site (Lancelle et al., 2015). The group velocity starts to decrease for frequencies greater than ~10 Hz, which was expected on the basis of a previous shear-wave velocity model (Steidl et al., 1996). Then, the phase velocity was calculated using the multichannel analysis of surface wave technique (MASW - Park et al., 1999) with 114 NCFs spaced one meter apart. The resulting dispersion curve between 5 and 15 Hz gave phase velocities that ranged from approximately 170 m/s at 15 Hz to 250 m/s at 5 Hz. These results are consistent with other results of active-source DAS and seismometer records obtained at the Garner Valley site (e.g., Stokoe et al. 2004). This analysis is

Study of multi-kilowatt solar arrays for Earth orbit applications

NASA Technical Reports Server (NTRS)

Patterson, R. E.

1983-01-01

A miniaturized Cassegrainian concentrator (MCC) solar array concept is being developed with the objective of significantly reducing the recurring cost of multikilowatt solar arrays. The desired cost reduction is obtained as a result of using very small high efficiency solar cells in conjuction with low cost optics. The MCC single element concept incident slar radiation is reflected rom a primary parabolic reflector to a secondary hyperbolic reflector and finally to a 4 millimeter diameter solar cell. A light catcher cone is used to improve off axis performance. The solar cell is mounted to a heat fin. An element is approximately 13 millimeters thick which permits efficient launch stowage of the concentrator system panels without complex optical component deployments or retractions. The MCC elements are packed in bays within graphite epoxy frames and are electrically connected into appropriate series-parallel circuits. A MCC sngle element with a 21 sq cm entrance aperture and a 20 efficient, 0.25 sq cm gallium arsenide solar cell has the same power output as 30 sq cm of 11-percent efficiency (at 68 C) silicon solar cells.

Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

NASA Technical Reports Server (NTRS)

Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.;

Millimeter radiation from a 3D model of the solar atmosphere. II. Chromospheric magnetic field

NASA Astrophysics Data System (ADS)

Loukitcheva, M.; White, S. M.; Solanki, S. K.; Fleishman, G. D.; Carlsson, M.

2017-05-01

Aims: We use state-of-the-art, three-dimensional non-local thermodynamic equilibrium (non-LTE) radiative magnetohydrodynamic simulations of the quiet solar atmosphere to carry out detailed tests of chromospheric magnetic field diagnostics from free-free radiation at millimeter and submillimeter wavelengths (mm/submm). Methods: The vertical component of the magnetic field was deduced from the mm/submm brightness spectra and the degree of circular polarization synthesized at millimeter frequencies. We used the frequency bands observed by the Atacama Large Millimeter/Submillimeter Array (ALMA) as a convenient reference. The magnetic field maps obtained describe the longitudinal magnetic field at the effective formation heights of the relevant wavelengths in the solar chromosphere. Results: The comparison of the deduced and model chromospheric magnetic fields at the spatial resolution of both the model and current observations demonstrates a good correlation, but has a tendency to underestimate the model field. The systematic discrepancy of about 10% is probably due to averaging of the restored field over the heights contributing to the radiation, weighted by the strength of the contribution. On the whole, the method of probing the longitudinal component of the magnetic field with free-free emission at mm/submm wavelengths is found to be applicable to measurements of the weak quiet-Sun magnetic fields. However, successful exploitation of this technique requires very accurate measurements of the polarization properties (primary beam and receiver polarization response) of the antennas, which will be the principal factor that determines the level to which chromospheric magnetic fields can be measured. Conclusions: Consequently, high-resolution and high-precision observations of circularly polarized radiation at millimeter wavelengths can be a powerful tool for producing chromospheric longitudinal magnetograms.

Submillimeter video imaging with a superconducting bolometer array

NASA Astrophysics Data System (ADS)

Becker, Daniel Thomas

Millimeter wavelength radiation holds promise for detection of security threats at a distance, including suicide bombers and maritime threats in poor weather. The high sensitivity of superconducting Transition Edge Sensor (TES) bolometers makes them ideal for passive imaging of thermal signals at millimeter and submillimeter wavelengths. I have built a 350 GHz video-rate imaging system using an array of feedhorn-coupled TES bolometers. The system operates at standoff distances of 16 m to 28 m with a measured spatial resolution of 1.4 cm (at 17 m). It currently contains one 251-detector sub-array, and can be expanded to contain four sub-arrays for a total of 1004 detectors. The system has been used to take video images that reveal the presence of weapons concealed beneath a shirt in an indoor setting. This dissertation describes the design, implementation and characterization of this system. It presents an overview of the challenges associated with standoff passive imaging and how these problems can be overcome through the use of large-format TES bolometer arrays. I describe the design of the system and cover the results of detector and optical characterization. I explain the procedure used to generate video images using the system, and present a noise analysis of those images. This analysis indicates that the Noise Equivalent Temperature Difference (NETD) of the video images is currently limited by artifacts of the scanning process. More sophisticated image processing algorithms can eliminate these artifacts and reduce the NETD to 100 mK, which is the target value for the most demanding passive imaging scenarios. I finish with an overview of future directions for this system.

Observations of basin ground motions from a dense seismic array in San Jose, California

USGS Publications Warehouse

Frankel, A.; Carver, D.; Cranswick, E.; Bice, T.; Sell, R.; Hanson, S.

2001-01-01

We installed a dense array of 41 digital seismographs in San Jose, California, to evaluate in detail the effects of a deep sedimentary basin and shallow sedimentary deposits on earthquake ground motions. This urban array is located near the eastern edge of the Santa Clara Valley and spans the Evergreen sedimentary basin identified by gravity data. Average station spacing is 1 km, with three stations initially spaced 110 m apart. Despite the high-noise urban environment, the stations of the array successfully triggered on and recorded small local earthquakes (M 2.5-2.8 at 10-25 km distance) and larger regional events such as the M 5.0 Bolinas earthquake (90 km distance), M 4.6-5.6 earthquakes near Mammoth Lakes (270 km distance), M 4.9-5.6 events in western Nevada (420 km distance) and the M 7.1 Hector Mine earthquake (590 km distance). Maps of spectral ratios across the array show that the highest amplitudes in all frequency bands studied (0.125-8 Hz) are generally observed at stations farther from the eastern edge of the Santa Clara Valley. Larger spectral amplitudes are often observed above the western edge of the Evergreen Basin. Snapshots of the recorded wavefield crossing the array for regional events to the east reveal that large, low-frequency (0.125-0.5 Hz) arrivals after the S-wave travel from south to north across the array. A moving-window, cross-correlation analysis finds that these later arrivals are surface waves traveling from the south. The timing and propagation direction of these arrivals indicates that they were likely produced by scattering of incident S waves at the border of the Santa Clara Valley to the south of the array. It is remarkable that the largest low-frequency phases at many of the valley sites for regional events to the east are basin surface waves coming from a direction about 70 degrees different from that of the epicenters. Basin surface waves emanating from the eastern edge of the valley are also identified by the cross

ATS-5 millimeter wave propagation measurements

NASA Technical Reports Server (NTRS)

Ippolito, L. J.

1973-01-01

Long term experimental measurements to determine the propagation characteristics of 15 and 32 GHz earth-space links and to evaluate performance characteristics of operational millimeter wave systems are reported. The ATS 5 millimeter wave experimental link experienced attenuation and fading characteristics as a function of rainfall rate and other meteorological parameters. A method of site selection for the lowest attenuation rainfall rate improved reception tremendously.

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): Fast-Scan Single-Dish Mapping

NASA Astrophysics Data System (ADS)

White, S. M.; Iwai, K.; Phillips, N. M.; Hills, R. E.; Hirota, A.; Yagoubov, P.; Siringo, G.; Shimojo, M.; Bastian, T. S.; Hales, A. S.; Sawada, T.; Asayama, S.; Sugimoto, M.; Marson, R. G.; Kawasaki, W.; Muller, E.; Nakazato, T.; Sugimoto, K.; Brajša, R.; Skokić, I.; Bárta, M.; Kim, S.; Remijan, A. J.; de Gregorio, I.; Corder, S. A.; Hudson, H. S.; Loukitcheva, M.; Chen, B.; De Pontieu, B.; Fleishmann, G. D.; Gary, D. E.; Kobelski, A.; Wedemeyer, S.; Yan, Y.

2017-07-01

The Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope has commenced science observations of the Sun starting in late 2016. Since the Sun is much larger than the field of view of individual ALMA dishes, the ALMA interferometer is unable to measure the background level of solar emission when observing the solar disk. The absolute temperature scale is a critical measurement for much of ALMA solar science, including the understanding of energy transfer through the solar atmosphere, the properties of prominences, and the study of shock heating in the chromosphere. In order to provide an absolute temperature scale, ALMA solar observing will take advantage of the remarkable fast-scanning capabilities of the ALMA 12 m dishes to make single-dish maps of the full Sun. This article reports on the results of an extensive commissioning effort to optimize the mapping procedure, and it describes the nature of the resulting data. Amplitude calibration is discussed in detail: a path that uses the two loads in the ALMA calibration system as well as sky measurements is described and applied to commissioning data. Inspection of a large number of single-dish datasets shows significant variation in the resulting temperatures, and based on the temperature distributions, we derive quiet-Sun values at disk center of 7300 K at λ = 3 mm and 5900 K at λ = 1.3 mm. These values have statistical uncertainties of about 100 K, but systematic uncertainties in the temperature scale that may be significantly larger. Example images are presented from two periods with very different levels of solar activity. At a resolution of about 25'', the 1.3 mm wavelength images show temperatures on the disk that vary over about a 2000 K range. Active regions and plages are among the hotter features, while a large sunspot umbra shows up as a depression, and filament channels are relatively cool. Prominences above the solar limb are a common feature of the single-dish images.

High power broadband millimeter wave TWTs

NASA Astrophysics Data System (ADS)

James, Bill G.

1999-05-01

In the early 1980's the requirement for high power broadband millimeter wave sources encouraged the development of microwave vacuum device amplifiers for radar and communication systems. Many government funded programs were implemented for the development of high power broadband millimeter wave amplifiers that would meet the needs of the high power community. The tube design capable of meeting these goals was the slow wave coupled cavity traveling wave device, which had a proven technology base at the lower frequencies (X Band). However scaling this technology to the millimeter frequencies had severe shortcomings in both thermal and manufacturing design. These shortcomings were overcome with the development of the Ladder Circuit technology. In conjunction with the circuit development high power electron beam systems had to be developed for the generation of high rf powers. These beam systems had to be capable of many megawatts of beam power density and high current densities. The cathode technology required to be capable of operating at current densities of 10 amperes per square centimeter at long pulse lengths and high duty cycle. Since the introduction of the Ladder Circuit technology a number of high power broadband millimeter wave amplifiers have been developed using this technology, and have been deployed in operating radar and communication systems. Broadband millimeter wave sources have been manufactured in the frequency range from 27 GHz to 100 GHz with power levels ranging from 100 watts to 50 kilowatts. Today the power levels achieved by these devices are nearing the limits of this technology; therefore to gain a significant increase in power at the millimeter wave frequencies other technologies will have to be considered particularly fast wave devices. This paper will briefly review the ladder circuit technology and present the designs of a number of broadband high power devices developed at Ka and W band. The discussion will include the beam systems

Image fusion based on millimeter-wave for concealed weapon detection

NASA Astrophysics Data System (ADS)

Zhu, Weiwen; Zhao, Yuejin; Deng, Chao; Zhang, Cunlin; Zhang, Yalin; Zhang, Jingshui

2010-11-01

This paper describes a novel multi sensors image fusion technology which is presented for concealed weapon detection (CWD). It is known to all, because of the good transparency of the clothes at millimeter wave band, a millimeter wave radiometer can be used to image and distinguish concealed contraband beneath clothes, for example guns, knives, detonator and so on. As a result, we adopt the passive millimeter wave (PMMW) imaging technology for airport security. However, in consideration of the wavelength of millimeter wave and the single channel mechanical scanning, the millimeter wave image has law optical resolution, which can't meet the need of practical application. Therefore, visible image (VI), which has higher resolution, is proposed for the image fusion with the millimeter wave image to enhance the readability. Before the image fusion, a novel image pre-processing which specifics to the fusion of millimeter wave imaging and visible image is adopted. And in the process of image fusion, multi resolution analysis (MRA) based on Wavelet Transform (WT) is adopted. In this way, the experiment result shows that this method has advantages in concealed weapon detection and has practical significance.

The large millimeter telescope/el Gran Telescopio Milimétrico: a new instrument for astrobiology.

PubMed

Irvine, William M; Carramiñana, Alberto; Carrasco, Luis; Schloerb, F Peter

2003-12-01

The Instituto Nacional de Astrofísica, Optica y Electrónica in Mexico and the University of Massachusetts in the U.S.A. are collaborating to build the world's largest radio telescope that operates at short millimeter wavelengths. This facility, known as the Large Millimeter Telescope (LMT) or el Gran Telescopio Milimétrico (GTM), is being sited at an altitude of 4600 m on Volcan Sierra Negra in the Mexican state of Puebla. The telescope will be a fully steerable dish with a diameter of 50 m and a surface consisting of 180 panels that are actively adjusted under computer control to correct for deformations due to gravity and temperature gradients. Instruments will include focal plane arrays to image both continuum and spectral line emission from celestial sources. The LMT/GTM will be an extremely powerful facility for studies encompassing almost all areas of astronomy, including astrobiology. In particular, the high sensitivity, angular resolution, and mapping speed will enable detailed investigations of the organic chemistry of interstellar molecular clouds, protoplanetary disks, and comets.

Study on Fins' Effect of Boiling Flow in Millimeter Channel Heat Exchanger

NASA Astrophysics Data System (ADS)

Watanabe, Satoshi

2005-11-01

Recently, a lot of researches about compact heat exchangers with mini-channels have been carried out with the hope of obtaining a high-efficiency heat transfer, due to the higher ratio of surface area than existing heat exchangers. However, there are many uncertain phenomena in fields such as boiling flow in mini-channels. Thus, in order to understand the boiling flow in mini-channels to design high-efficiency heat exchangers, this work focused on the visualization measurement of boiling flow in a millimeter channel. A transparent acrylic channel (heat exchanger form), high-speed camera (2000 fps at 1024 x 1024 pixels), and halogen lamp (backup light) were used as the visualization system. The channel's depth is 2 mm, width is 30 mm, and length is 400 mm. In preparation for commercial use, two types of channels were experimented on: a fins type and a normal slit type (without fins). The fins are circular cylindrical obstacles (diameter is 5 mm) to promote heat transfer, set in a triangular array (distance between each center point is 10 mm). Especially in this work, boiling flow and heat transfer promotion in the millimeter channel heat exchanger with fins was evaluated using a high-speed camera.

Conformal atomic layer deposition of alumina on millimeter tall, vertically-aligned carbon nanotube arrays.

PubMed

Stano, Kelly L; Carroll, Murphy; Padbury, Richard; McCord, Marian; Jur, Jesse S; Bradford, Philip D

2014-11-12

Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.

Self-Anchored Catalyst Interface Enables Ordered Via Array Formation from Submicrometer to Millimeter Scale for Polycrystalline and Single-Crystalline Silicon.

PubMed

Kim, Jeong Dong; Kim, Munho; Kong, Lingyu; Mohseni, Parsian K; Ranganathan, Srikanth; Pachamuthu, Jayavel; Chim, Wai Kin; Chiam, Sing Yang; Coleman, James J; Li, Xiuling

2018-03-14

Defying text definitions of wet etching, metal-assisted chemical etching (MacEtch), a solution-based, damage-free semiconductor etching method, is directional, where the metal catalyst film sinks with the semiconductor etching front, producing 3D semiconductor structures that are complementary to the metal catalyst film pattern. The same recipe that works perfectly to produce ordered array of nanostructures for single-crystalline Si (c-Si) fails completely when applied to polycrystalline Si (poly-Si) with the same doping type and level. Another long-standing challenge for MacEtch is the difficulty of uniformly etching across feature sizes larger than a few micrometers because of the nature of lateral etching. The issue of interface control between the catalyst and the semiconductor in both lateral and vertical directions over time and over distance needs to be systematically addressed. Here, we present a self-anchored catalyst (SAC) MacEtch method, where a nanoporous catalyst film is used to produce nanowires through the pinholes, which in turn physically anchor the catalyst film from detouring as it descends. The systematic vertical etch rate study as a function of porous catalyst diameter from 200 to 900 nm shows that the SAC-MacEtch not only confines the etching direction but also enhances the etch rate due to the increased liquid access path, significantly delaying the onset of the mass-transport-limited critical diameter compared to nonporous catalyst c-Si counterpart. With this enhanced mass transport approach, vias on multistacks of poly-Si/SiO 2 are also formed with excellent vertical registry through the polystack, even though they are separated by SiO 2 which is readily removed by HF alone with no anisotropy. In addition, 320 μm square through-Si-via (TSV) arrays in 550 μm thick c-Si are realized. The ability of SAC-MacEtch to etch through poly/oxide/poly stack as well as more than half millimeter thick silicon with excellent site specificity for a wide

A concordant scenario to explain FU Orionis from deep centimeter and millimeter interferometric observations

NASA Astrophysics Data System (ADS)

Liu, Hauyu Baobab; Vorobyov, Eduard I.; Dong, Ruobing; Dunham, Michael M.; Takami, Michihiro; Galván-Madrid, Roberto; Hashimoto, Jun; Kóspál, Ágnes; Henning, Thomas; Tamura, Motohide; Rodríguez, Luis F.; Hirano, Naomi; Hasegawa, Yasuhiro; Fukagawa, Misato; Carrasco-Gonzalez, Carlos; Tazzari, Marco

2017-06-01

Aims: The aim of this work is to constrain properties of the disk around the archetype FU Orionis object, FU Ori, with as good as 25 au resolution. Methods: We resolved FU Ori at 29-37 GHz using the Karl G. Jansky Very Large Array (JVLA) in the A-array configuration, which provided the highest possible angular resolution to date at this frequency band ( 0.07 arcsec). We also performed complementary JVLA 8-10 GHz observations, Submillimeter Array (SMA) 224 GHz and 272 GHz observations, and compared these with archival Atacama Large Millimeter Array (ALMA) 346 GHz observations to obtain the spectral energy distributions (SEDs). Results: Our 8-10 GHz observations do not find evidence for the presence of thermal radio jets, and constrain the radio jet/wind flux to at least 90 times lower than the expected value from the previously reported bolometric luminosity-radio luminosity correlation. The emission at frequencies higher than 29 GHz may be dominated by the two spatially unresolved sources, which are located immediately around FU Ori and its companion FU Ori S, respectively. Their deconvolved radii at 33 GHz are only a few au, which is two orders of magnitude smaller in linear scale than the gaseous disk revealed by the previous Subaru-HiCIAO 1.6 μm coronagraphic polarization imaging observations. We are struck by the fact that these two spatially compact sources contribute to over 50% of the observed fluxes at 224 GHz, 272 GHz, and 346 GHz. The 8-346 GHz SEDs of FU Ori and FU Ori S cannot be fit by constant spectral indices (over frequency), although we cannot rule out that it is due to the time variability of their (sub)millimeter fluxes. Conclusions: The more sophisticated models for SEDs considering the details of the observed spectral indices in the millimeter bands suggest that the >29 GHz emission is contributed by a combination of free-free emission from ionized gas and thermal emission from optically thick and optically thin dust components. We hypothesize

High Power Broadband Millimeter Wave TWTs

NASA Astrophysics Data System (ADS)

James, Bill G.

1998-04-01

In the early 1980's the requirement for high power broadband millimeter wave sources encouraged the development of microwave vacuum device amplifiers for radar and communication systems. Many government funded programs were implemented for the development of high power broadband millimeter wave amplifiers that would meet the needs of the high power community. The tube design capable of meeting these goals was the slow wave coupled cavity traveling wave device, which had a proven technology base at the lower frequencies (X Band). However scaling this technology to the millimeter frequencies had severe shortcomings in both thermal and manufacturing design. These shortcomings were overcome with the development of the Ladder Circuit technology. In conjunction with the circuit development high power electron beam systems had to be developed for the generation of high rf powers. These beam systems had to be capable of many megawatts of beam power density and high current densities. The cathode technology required to be capable of operating at current densities of 10 amperes per square centimeter at long pulse lengths and high duty cycle. Since the introduction of the Ladder Circuit technology a number of high power broadband millimeter wave amplifiers have been developed and deployed in operating radar and communication systems. Broadband millimeter wave sources have been manufactured in the frequency range from 27 GHz to 100 GHz with power levels ranging from 100 watts CW to 10 kilowatts Peak at W band over a 2 GHz bandwidth. Also a 50 kW peak power and 10 kW average power device at Ka band with 2 GHz bandwidth has been developed. Today the power levels achieved by these devices are nearing the limits of this technology; therefore to gain a significant increase in power at the millimeter wave frequencies, other technologies will have to be considered, particularly fast wave devices. This paper will briefly review the ladder circuit technology and present the designs of

Millimeter-wave monolithic diode-grid frequency multiplier

NASA Technical Reports Server (NTRS)

Maserjian, Joseph (Inventor)

1990-01-01

A semiconductor diode structure useful for harmonic generation of millimeter or submillimeter wave radiation from a fundamental input wave is fabricated on a GaAs substrate. A heavily doped layer of n(sup ++) GaAs is produced on the substrate and then a layer of intrinsic GaAs on said heavily doped layer on top of which a sheet of heavy doping (++) is produced. A thin layer of intrinsic GaAs grown over the sheet is capped with two metal contacts separated by a gap to produce two diodes connected back to back through the n(sup ++) layer for multiplication of frequency by an odd multiple. If only one metal contact caps the thin layer of intrinsic GaAs, the second diode contact is produced to connect to the n(sup ++) layer for multiplication of frequency by an even number. The odd or even frequency multiple is selected by a filter. A phased array of diodes in a grid will increase the power of the higher frequency generated.

Millimeter spatial resolution in vivo sodium MRI of the human eye at 7 T using a dedicated radiofrequency transceiver array.

PubMed

Wenz, Daniel; Kuehne, Andre; Huelnhagen, Till; Nagel, Armin M; Waiczies, Helmar; Weinberger, Oliver; Oezerdem, Celal; Stachs, Oliver; Langner, Soenke; Seeliger, Erdmann; Flemming, Bert; Hodge, Russell; Niendorf, Thoralf

2018-08-01

The aim of this study was to achieve millimeter spatial resolution sodium in vivo MRI of the human eye at 7 T using a dedicated six-channel transceiver array. We present a detailed description of the radiofrequency coil design, along with electromagnetic field and specific absorption ratio simulations, data validation, and in vivo application. Electromagnetic field and specific absorption ratio simulations were performed. Transmit field uniformity was optimized by using a multi-objective genetic algorithm. Transmit field mapping was conducted using a phase-sensitive method. An in vivo feasibility study was carried out with 3-dimensional density-adapted projection reconstruction imaging technique. Measured transmit field distribution agrees well with the one obtained from simulations. The specific absorption ratio simulations confirm that the radiofrequency coil is safe for clinical use. Our radiofrequency coil is light and conforms to an average human head. High spatial resolution (nominal 1.4 and 1.0 mm isotropic) sodium in vivo images of the human eye were acquired within scan times suitable for clinical applications (∼ 10 min). Three most important eye compartments in the context of sodium physiology were clearly delineated in all of the images: the vitreous humor, the aqueous humor, and the lens. Our results provide encouragement for further clinical studies. The implications for research into eye diseases including ocular melanoma, cataract, and glaucoma are discussed. Magn Reson Med 80:672-684, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

The development of inflatable array antennas

NASA Technical Reports Server (NTRS)

Huang, J.

2001-01-01

Inflatable array antennas are being developed to significantly reduce the mass, the launch vehicle's stowage volume, and the cost of future spacecraft systems. Three inflatable array antennas, recently developed for spacecraft applications, are a 3.3 m x 1.0 m L-band synthetic-aperture radar (SAR) array, a 1.0 m-diameter X-band telecom reflectarray, and a 3 m-diameter Ka-band telecom reflectarray. All three antennas are similar in construction, and each consists of an inflatable tubular frame that supports and tensions a multi-layer thin-membrane RF radiating surface with printed microstrip patches. The L-band SAR array achieved a bandwidth of 80 MHz, an aperture efficiency of 74%, and a total mass of 15 kg. The X-band reflectarray achieved an aperture efficiency of 37%, good radiation patterns, and a total mass of 1.2 kg (excluding the inflation system). The 3 m Ka-band reflectarray achieved a surface flatness of 0.1 mm RMS, good radiation patterns, and a total mass of 12.8 kg (excluding the inflation system). These antennas demonstrated that inflatable arrays are feasible across the microwave and millimeter-wave spectrums. Further developments of these antennas are deemed necessary, in particular, in the area of qualifying the inflatable structures for space-environment usage.

Millimeter Wave Sensor For On-Line Inspection Of Thin Sheet Dielectrics

DOEpatents

Bakhtiari, Sasan; Gopalsami, Nachappa; Raptis, Apostolos C.

1999-03-23

A millimeter wave sensor is provided for non-destructive inspection of thin sheet dielectric materials. The millimeter wave sensor includes a Gunn diode oscillator (GDO) source generating a mill meter wave electromagnetic energy signal having a single frequency. A heater is coupled to the GDO source for stabilizing the single frequency. A small size antenna is coupled to the GDO source for transmitting the millimeter wave electromagnetic energy signal to a sample material and for receiving a reflected millimeter wave electromagnetic energy signal from the sample material. Ferrite circulator isolators coupled between the GDO source and the antenna separate the millimeter wave electromagnetic energy signal into transmitted and received electromagnetic energy signal components and a detector detects change in both amplitude and phase of the transmitted and received electromagnetic energy signal components. A millimeter wave sensor is provided for non-destructive inspection of thin sheet dielectric materials. The millimeter wave sensor includes a Gunn diode oscillator (GDO) source generating a mill meter wave electromagnetic energy signal having a single frequency. A heater is coupled to the GDO source for stabilizing the single frequency. A small size antenna is coupled to the GDO source for transmitting the millimeter wave electromagnetic energy signal to a sample material and for receiving a reflected millimeter wave electromagnetic energy signal from the sample material. Ferrite circulator isolators coupled between the GDO source and the antenna separate the millimeter wave electromagnetic energy signal into transmitted and received electromagnetic energy signal components and a detector detects change in both amplitude and phase of the transmitted and received electromagnetic energy signal components.

Wide-field microscopy using microcamera arrays

NASA Astrophysics Data System (ADS)

Marks, Daniel L.; Youn, Seo Ho; Son, Hui S.; Kim, Jungsang; Brady, David J.

2013-02-01

A microcamera is a relay lens paired with image sensors. Microcameras are grouped into arrays to relay overlapping views of a single large surface to the sensors to form a continuous synthetic image. The imaged surface may be curved or irregular as each camera may independently be dynamically focused to a different depth. Microcamera arrays are akin to microprocessors in supercomputers in that both join individual processors by an optoelectronic routing fabric to increase capacity and performance. A microcamera may image ten or more megapixels and grouped into an array of several hundred, as has already been demonstrated by the DARPA AWARE Wide-Field program with multiscale gigapixel photography. We adapt gigapixel microcamera array architectures to wide-field microscopy of irregularly shaped surfaces to greatly increase area imaging over 1000 square millimeters at resolutions of 3 microns or better in a single snapshot. The system includes a novel relay design, a sensor electronics package, and a FPGA-based networking fabric. Biomedical applications of this include screening for skin lesions, wide-field and resolution-agile microsurgical imaging, and microscopic cytometry of millions of cells performed in situ.

A Total Lightning Climatology for the Tennessee Valley Region

NASA Technical Reports Server (NTRS)

McCaul, E. W.; Goodman, S. J.; Buechler, D. E.; Blakeslee, R.; Christian, H.; Boccippio, D.; Koshak, W.; Bailey, J.; Hallm, J.; Bateman, M.

2003-01-01

Total flash counts derived from the North Alabama Lightning Mapping Array are being processed for 2002 to form a climatology of total lightning for the Tennessee Valley region. The data from this active and interesting period will be compared to data fiom the National Lightning Detection Network, space-based lightning sensors, and weather radars.

Millimeter wave micro-CPW integrated antenna

NASA Astrophysics Data System (ADS)

Tzuang, Ching-Kuang C.; Lin, Ching-Chyuan

1996-12-01

This paper presents the latest result of applying the microstrip's leaky mode for a millimeter-wave active integrated antenna design. In contrast to the use of the first higher-order leaky mode, the second higher-order leaky mode, the second higher-order leaky mode of even symmetry is employed in the new approach, which allows larger dimension for leaky-wave antenna design and thereby reduces its performance sensitivity to the photolithographic tolerance. The new active integrated antenna operating at frequency about 34 GHz comprises of a microstrip and a coplanar waveguide stacked on top of each other, named as the millimeter wave micro-CPW integrated antenna. The feed is through the CPW that would be connected to the active uniplanar millimeter-wave (M)MIC's. Our experimental and theoretical investigations on the new integrated antenna show good input matching characteristics for such a highly directed leaky-wave antenna with the first-pass success.

High Angular Resolution Microwave Sensing with Large, Sparse, Random Arrays

DTIC Science & Technology

1983-11-01

RESEARCH AFOSR 82-0012 DTIC s" A6 19M UNIVERSITY of PENNSYLVANIA VALLEY FORGE RESEARCH CENTER THE MOORE SCHOOL OF ELECTRICAL ENGINEERING PHILADELPHIA...MICROWAVE SENSING WITH LARGE, SPARSE, RANDOM ARRAYS Final Scientific Report AIR FORCE OFFICE OF SCIENTIFIC RESEARCH AFOSR 82-0012 Valley Forge Research ...CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Air Force Office of Scientific Research /NE Nov 1983 - . Bildin 41073. NUMBER Or PAG ES BOllinZ AFB, DIC

Millimeter wave transmission systems and related devices

NASA Technical Reports Server (NTRS)

Hebert, L. M.

1984-01-01

A survey was made of the state-of-the-art in millimeter (20 GHz to 300 GHz) wave transmission systems and related devices. The survey includes summaries of analytical studies and theoretical results that were obtained for various transmission line structures. This material was supplemented by further analysis where appropriate. The transmission line structures are evaluated in terms of electrical performance, ease of manufacture, usefulness for building other devices and compatibility with solid state devices. Descriptions of waveguide transmission lines which have commonly been used in the microwave frequency range are provided along with special attention given to the problems that these guides face when their use is extended into the millimeter wave range. Also, guides which have been introduced specifically to satisfy the requirements of millimeter wave transmission are discussed in detail.

Millimeter-wave active probe

DOEpatents

Majidi-Ahy, Gholamreza; Bloom, David M.

1991-01-01

A millimeter-wave active probe for use in injecting signals with frequencies above 50GHz to millimeter-wave and ultrafast devices and integrated circuits including a substrate upon which a frequency multiplier consisting of filter sections and impedance matching sections are fabricated in uniplanar transmission line format. A coaxial input and uniplanar 50 ohm transmission line couple an approximately 20 GHz input signal to a low pass filter which rolls off at approximately 25 GHz. An input impedance matching section couples the energy from the low pass filter to a pair of matched, antiparallel beam lead diodes. These diodes generate odd-numberd harmonics which are coupled out of the diodes by an output impedance matching network and bandpass filter which suppresses the fundamental and third harmonics and selects the fifth harmonic for presentation at an output.

Resolution-Adaptive Hybrid MIMO Architectures for Millimeter Wave Communications

NASA Astrophysics Data System (ADS)

Choi, Jinseok; Evans, Brian L.; Gatherer, Alan

2017-12-01

In this paper, we propose a hybrid analog-digital beamforming architecture with resolution-adaptive ADCs for millimeter wave (mmWave) receivers with large antenna arrays. We adopt array response vectors for the analog combiners and derive ADC bit-allocation (BA) solutions in closed form. The BA solutions reveal that the optimal number of ADC bits is logarithmically proportional to the RF chain's signal-to-noise ratio raised to the 1/3 power. Using the solutions, two proposed BA algorithms minimize the mean square quantization error of received analog signals under a total ADC power constraint. Contributions of this paper include 1) ADC bit-allocation algorithms to improve communication performance of a hybrid MIMO receiver, 2) approximation of the capacity with the BA algorithm as a function of channels, and 3) a worst-case analysis of the ergodic rate of the proposed MIMO receiver that quantifies system tradeoffs and serves as the lower bound. Simulation results demonstrate that the BA algorithms outperform a fixed-ADC approach in both spectral and energy efficiency, and validate the capacity and ergodic rate formula. For a power constraint equivalent to that of fixed 4-bit ADCs, the revised BA algorithm makes the quantization error negligible while achieving 22% better energy efficiency. Having negligible quantization error allows existing state-of-the-art digital beamformers to be readily applied to the proposed system.

Earthquake Hazard Class Mapping by Parcel in Las Vegas Valley

NASA Astrophysics Data System (ADS)

Pancha, A.; Pullammanappallil, S.; Louie, J. N.; Hellmer, W. K.

2011-12-01

Clark County, Nevada completed the very first effort in the United States to map earthquake hazard class systematically through an entire urban area. The map is used in development and disaster response planning, in addition to its direct use for building code implementation and enforcement. The County contracted with the Nevada System of Higher Education to classify about 500 square miles including urban Las Vegas Valley, and exurban areas considered for future development. The Parcel Map includes over 10,000 surface-wave array measurements accomplished over three years using Optim's SeisOpt° ReMi measurement and processing techniques adapted for large scale data. These array measurements classify individual parcels on the NEHRP hazard scale. Parallel "blind" tests were conducted at 93 randomly selected sites. The rms difference between the Vs30 values yielded by the blind data and analyses and the Parcel Map analyses is 4.92%. Only six of the blind-test sites showed a difference with a magnitude greater than 10%. We describe a "C+" Class for sites with Class B average velocities but soft surface soil. The measured Parcel Map shows a clearly definable C+ to C boundary on the west side of the Valley. The C to D boundary is much more complex. Using the parcel map in computing shaking in the Valley for scenario earthquakes is crucial for obtaining realistic predictions of ground motions.

Producibility consideration for millimeter-wave transceivers

NASA Astrophysics Data System (ADS)

Seashore, Charles R.

1995-10-01

Considerable progress has been made in the development and demonstration of millimeter wave MMIC technology up to frequencies approaching 100 GHz. The recently completed multiyear, ARPA-sponsored, MIMIC program provided a considerable amount of funding and government-contractor team energy to advance the state-of-art with a number of important GaAs-based transceiver building blocks. Unfortuanely, producibility of millimeter wave MMIC transceiver modules has not been similarly addressed to provide a truly low cost, marketable product. This paper considers the module producibility problem and its various technological implications.

A Weak Bar Potential and Massive Core in the Seyfert 2 Galaxy NGC 3079: CO(1--0) observations using the Nobeyama Millimeter Array

NASA Astrophysics Data System (ADS)

Koda, J.; Sofue, Y.; Kohno, K.; Okumura, S. K.; Irwin, Judith A.

We present our recent 12CO (1-0) observations in the central molecular disk of the Hα/radio lobe galaxy NGC 3079 with the Nobeyama Millimeter Array. We show four kinematically distinct components in the observed molecular disk: a main disk, spiral arms, a nuclear disk and a nuclear core. We discuss their possible origins using a simple orbit-analysis model in a weak bar potential. We show that three of the four components are well-understood by typical gaseous orbits in a weak bar, such as gaseous x1- and x2-orbits. The main disk and spiral arms are well-understood as the gaseous x1-orbits and their associated crowding, respectively. The nuclear disk is naturally explained by the x2-orbits. However, the nuclear core, showing a high velocity of about 200kmps at a radius of about 100pc, cannot be explained by those gaseous orbits in a bar. Furthermore, no other orbits, derived by bars, cannot be responsible for the nuclear core. Thus we discuss that this component should be attributed to a central massive core with a dynamical mass of about 109Msun within the central 100pc radius. This mass is three orders of magnitude more massive than that of a central black hole in this galaxy. More detailed descriptions are presented in Koda et al. (2002).

A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER

NASA Astrophysics Data System (ADS)

Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

2014-05-01

, occupy minimum cabin space and maximize scan coverage, a pod-based configuration was adopted. Currently, the radar system is capable of collecting observations between zenith and nadir in a fixed scanning mode. Measurements are corrected for aircraft attitude changes. The near-nadir and zenith pointing observations minimize the cross-track Doppler contamination in the radial velocity measurements. An extensive engineering monitoring mechanism is built into the recording system status such as temperature, pressure, various electronic components' status and receiver characteristics. Status parameters are used for real-time system stability estimates and correcting radar system parameters. The pod based radar system is mounted on a modified Gulfstream V aircraft, which is operated and maintained by the National Center for Atmospheric Research (NCAR) on behalf of the National Science Foundation (NSF). The aircraft is called the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) (Laursen et al., 2006). It is also instrumented with high spectral resolution lidar (HSRL) and an array of in situ and remote sensors for atmospheric research. As part of the instrument suite for HIAPER, the NSF funded the development of the HIAPER Cloud Radar (HCR). The HCR is an airborne, millimeter-wavelength, dual-polarization, Doppler radar that serves the atmospheric science community by providing cloud remote sensing capabilities for the NSF/NCAR G-V (HIAPER) aircraft. An optimal radar configuration that is capable of maximizing the accuracy of both qualitative and quantitative estimated cloud microphysical and dynamical properties is the most attractive option to the research community. The Technical specifications of cloud radar are optimized for realizing the desired scientific performance for the pod-based configuration. The radar was both ground and flight tested and preliminary measurements of Doppler and polarization measurements were collected. HCR

Sub-Millimeter Heterodyne Focal-Plane Arrays for High-Resolution Astronomical Spectroscopy

NASA Astrophysics Data System (ADS)

Goldsmith, Paul F.

2017-09-01

Spectral lines are vital tools for astronomy, particularly for studying the interstellar medium, which is widely distributed throughout the volume of our Milky Way and of other galaxies. Broadband emissions, including synchrotron, free-free, and thermal dust emissions give astronomers important information. However, they do not give information about the motions of, for example, interstellar clouds, the filamentary structures found within them, star-forming dense cores, and photon-dominated regions energized by massive young stars. For study of the interstellar medium, spectral lines at sub-millimeter wavelengths are particularly important, for two reasons. First, they offer the unique ability to observe a variety of important molecules, atoms, and ions, which are the most important gas coolants (fine-structure lines of ionized and neutral carbon, neutral oxygen), probes of physical conditions (high-J transitions of CO, HF, fine-structure lines of ionized nitrogen), and of obvious biogenic importance (H2O). In addition, high-resolution observations of spectral lines offer the unique ability to disentangle the complex motions within these regions and, in some cases, to determine their arrangement along the line of sight. To accomplish this, spectral resolution high enough to resolve the spectral lines of interest is required. We can measure the resolution of the spectrometer in terms of its resolution, R = f/δf, where f is the rest frequency of the line, and δJ is the frequency resolution of the spectrometer. More-active sources can be advantageously studied with R = 3 × 10^5, while more quiescent sources require R as high as 10^7.

Amplifier based broadband pixel for sub-millimeter wave imaging

NASA Astrophysics Data System (ADS)

Sarkozy, Stephen; Drewes, Jonathan; Leong, Kevin M. K. H.; Lai, Richard; Mei, X. B. (Gerry); Yoshida, Wayne; Lange, Michael D.; Lee, Jane; Deal, William R.

2012-09-01

Broadband sub-millimeter wave technology has received significant attention for potential applications in security, medical, and military imaging. Despite theoretical advantages of reduced size, weight, and power compared to current millimeter wave systems, sub-millimeter wave systems have been hampered by a fundamental lack of amplification with sufficient gain and noise figure properties. We report a broadband pixel operating from 300 to 340 GHz, biased off a single 2 V power supply. Over this frequency range, the amplifiers provide > 40 dB gain and <8 dB noise figure, representing the current state-of-art performance capabilities. This pixel is enabled by revolutionary enhancements to indium phosphide (InP) high electron mobility transistor technology, based on a sub-50 nm gate and indium arsenide composite channel with a projected maximum oscillation frequency fmax>1.0 THz. The first sub-millimeter wave-based images using active amplification are demonstrated as part of the Joint Improvised Explosive Device Defeat Organization Longe Range Personnel Imager Program. This development and demonstration may bring to life future sub-millimeter-wave and THz applications such as solutions to brownout problems, ultra-high bandwidth satellite communication cross-links, and future planetary exploration missions.

Millimeter-wave spectra of the Jovian planets

NASA Technical Reports Server (NTRS)

Joiner, Joanna; Steffes, Paul G.

1991-01-01

The millimeter wave portion of the electromagnetic spectrum is critical for understanding the subcloud atmospheric structure of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune). This research utilizes a combination of laboratory measurements, computer modeling, and radio astronomical observation in order to obtain a better understanding of the millimeter-wave spectra of the Jovian planets. The pressure broadened absorption from gaseous ammonia (NH3) and hydrogen sulfide (H2S) was measured in the laboratory under simulated conditions for the Jovian atmospheres. Researchers developed new formalisms for computing the absorptivity of gaseous NH3 and H2S based on their laboratory measurements. They developed a radiative transfer and thermochemical model to predict the abundance and distribution of absorbing constituents in the Jovian atmospheres. They used the model to compute the millimeter wave emission from the Jovian planets.

A DUAL-BAND MILLIMETER-WAVE KINETIC INDUCTANCE CAMERA FOR THE IRAM 30 m TELESCOPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monfardini, A.; Benoit, A.; Bideaud, A.

The Neel IRAM KIDs Array (NIKA) is a fully integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. The instrument includes dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz. The imaging sensors consist of two spatially separated arrays of KIDs. The first array, mounted on the 150 GHz branch, is composed of 144 lumped-element KIDs. The second array (220 GHz) consists of 256 antenna-coupled KIDs. Each of the arrays is sensitive to a single polarization; the band splitting is achieved by using a grid polarizer. The optics and sensors aremore » mounted in a custom dilution cryostat, with an operating temperature of {approx}70 mK. Electronic readout is realized using frequency multiplexing and a transmission line geometry consisting of a coaxial cable connected in series with the sensor array and a low-noise 4 K amplifier. The dual-band NIKA was successfully tested in 2010 October at the Institute for Millimetric Radio Astronomy (IRAM) 30 m telescope at Pico Veleta, Spain, performing in-line with laboratory predictions. An optical NEP was then calculated to be around 2 x 10{sup -16} W Hz{sup -1/2} (at 1 Hz) while under a background loading of approximately 4 pW pixel{sup -1}. This improvement in comparison with a preliminary run (2009) verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically relevant faint and extended objects were then imaged including the Galactic Center SgrB2 (FIR1), the radio galaxy Cygnus A, and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows.« less

Dimension-Factorized Range Migration Algorithm for Regularly Distributed Array Imaging

PubMed Central

Guo, Qijia; Wang, Jie; Chang, Tianying

2017-01-01

The two-dimensional planar MIMO array is a popular approach for millimeter wave imaging applications. As a promising practical alternative, sparse MIMO arrays have been devised to reduce the number of antenna elements and transmitting/receiving channels with predictable and acceptable loss in image quality. In this paper, a high precision three-dimensional imaging algorithm is proposed for MIMO arrays of the regularly distributed type, especially the sparse varieties. Termed the Dimension-Factorized Range Migration Algorithm, the new imaging approach factorizes the conventional MIMO Range Migration Algorithm into multiple operations across the sparse dimensions. The thinner the sparse dimensions of the array, the more efficient the new algorithm will be. Advantages of the proposed approach are demonstrated by comparison with the conventional MIMO Range Migration Algorithm and its non-uniform fast Fourier transform based variant in terms of all the important characteristics of the approaches, especially the anti-noise capability. The computation cost is analyzed as well to evaluate the efficiency quantitatively. PMID:29113083

Beamforming Based Full-Duplex for Millimeter-Wave Communication

PubMed Central

Liu, Xiao; Xiao, Zhenyu; Bai, Lin; Choi, Jinho; Xia, Pengfei; Xia, Xiang-Gen

2016-01-01

In this paper, we study beamforming based full-duplex (FD) systems in millimeter-wave (mmWave) communications. A joint transmission and reception (Tx/Rx) beamforming problem is formulated to maximize the achievable rate by mitigating self-interference (SI). Since the optimal solution is difficult to find due to the non-convexity of the objective function, suboptimal schemes are proposed in this paper. A low-complexity algorithm, which iteratively maximizes signal power while suppressing SI, is proposed and its convergence is proven. Moreover, two closed-form solutions, which do not require iterations, are also derived under minimum-mean-square-error (MMSE), zero-forcing (ZF), and maximum-ratio transmission (MRT) criteria. Performance evaluations show that the proposed iterative scheme converges fast (within only two iterations on average) and approaches an upper-bound performance, while the two closed-form solutions also achieve appealing performances, although there are noticeable differences from the upper bound depending on channel conditions. Interestingly, these three schemes show different robustness against the geometry of Tx/Rx antenna arrays and channel estimation errors. PMID:27455256

Valley Topological Phases in Bilayer Sonic Crystals

NASA Astrophysics Data System (ADS)

Lu, Jiuyang; Qiu, Chunyin; Deng, Weiyin; Huang, Xueqin; Li, Feng; Zhang, Fan; Chen, Shuqi; Liu, Zhengyou

2018-03-01

Recently, the topological physics in artificial crystals for classical waves has become an emerging research area. In this Letter, we propose a unique bilayer design of sonic crystals that are constructed by two layers of coupled hexagonal array of triangular scatterers. Assisted by the additional layer degree of freedom, a rich topological phase diagram is achieved by simply rotating scatterers in both layers. Under a unified theoretical framework, two kinds of valley-projected topological acoustic insulators are distinguished analytically, i.e., the layer-mixed and layer-polarized topological valley Hall phases, respectively. The theory is evidently confirmed by our numerical and experimental observations of the nontrivial edge states that propagate along the interfaces separating different topological phases. Various applications such as sound communications in integrated devices can be anticipated by the intriguing acoustic edge states enriched by the layer information.

Kilopixel Pop-Up Bolometer Arrays for the Atacama Cosmology Telescope

NASA Technical Reports Server (NTRS)

Chervenak, J. A.; Wollack, E.; Henry, R.; Moseley, S. H.; Niemack, M.; Staggs, S.; Page, L.; Doriese, R.; Hilton, G. c.; Irwin, K. D.

2007-01-01

The recently deployed Atacama Cosmology Telescope (ACT) anticipates first light on its kilopixel array of close-packed transition-edge-sensor bolometers in November of 2007. The instrument will represent a full implementation of the next-generation, large format arrays for millimeter wave astronomy that use superconducting electronics and detectors. Achieving the practical construction of such an array is a significant step toward producing advanced detector arrays for future SOFIA instruments. We review the design considerations for the detector array produced for the ACT instrument. The first light imager consists of 32 separately instrumented 32-channel pop-up bolometer arrays (to create a 32x32 filled array of mm-wave sensors). Each array is instrumented with a 32-channel bias resistor array, Nyquist filter array, and time-division SQUID multiplexer. Each component needed to be produced in relatively large quantities with suitable uniformity to meet tolerances for array operation. An optical design was chosen to maximize absorption at the focal plane while mitigating reflections and stray light. The pop-up geometry (previously implemented with semiconducting detectors and readout on the SHARC II and HAWC instruments) enabled straightforward interface of the superconducting bias and readout circuit with the 2D array of superconducting bolometers. The array construction program balanced fabrication challenges with assembly challenges to deliver the instrument in a timely fashion. We present some of the results of the array build and characterization of its performance.

Transition-Edge Hot-Electron Microbolometers for Millimeter and Submillimeter Astrophysics

NASA Technical Reports Server (NTRS)

Hsieh, Wen-Ting; Stevenson, Thomas; U-yen, Kongpop; Wollack, Edward; Barrentine, Emily

2014-01-01

The millimeter and the submillimeter wavelengths of the electromagnetic spectrum hold a wealth of information about the evolution of the universe. In particular, cosmic microwave background (CMB) radiation and its polarization carry the oldest information in the universe, and provide the best test of the inflationary paradigm available to astronomy today. Detecting gravity waves through their imprint on the CMB polarization would have extraordinary repercussions for cosmology and physics. A transition-edge hot-electron micro - bolometer (THM) consists of a superconducting bilayer transition-edge sensor (TES) with a thin-film absorber. Unlike traditional monolithic bolometers that make use of micromachined structures, the THM em ploys the decoupling between electrons and phonons at millikelvin temperatures to provide thermal isolation. The devices are fabricated photolithographically and are easily integrated with antennas via microstrip transmission lines, and with SQUID (superconducting quantum interference device) readouts. The small volume of the absorber and TES produces a short thermal time constant that facilitates rapid sky scanning. The THM consists of a thin-film metal absorber overlapping a superconducting TES. The absorber forms the termination of a superconducting microstripline that carries RF power from an antenna. The purpose of forming a separate absorber and TES is to allow flexibility in the optimization of the two components. In particular, the absorbing film's impedance can be chosen to match the antenna, while the TES impedance can be chosen to match to the readout SQUID amplifier. This scheme combines the advantages of the TES with the advantages of planar millimeter-wave transmission line circuits. Antenna-coupling to the detectors via planar transmission lines allows the detector dimensions to be much smaller than a wavelength, so the technique can be extended across the entire microwave, millimeter, and submillimeter wavelength ranges. The

Millimeter-wave detection using resonant tunnelling diodes

NASA Technical Reports Server (NTRS)

Mehdi, I.; Kidner, C.; East, J. R.; Haddad, G. I.

1990-01-01

A lattice-matched InGaAs/InAlAs resonant tunnelling diode is studied as a video detector in the millimeter-wave range. Tangential signal sensitivity and video resistance measurements are made as a function of bias and frequency. A tangential signal sensitivity of -37 dBm (1 MHz amplifier bandwidth) with a corresponding video resistance of 350 ohms at 40 GHz has been measured. These results appear to be the first millimeter-wave tangential signal sensitivity and video resistance results for a resonant tunnelling diode.

ACTIVITIES: Centimeter and Millimeter Measurements

ERIC Educational Resources Information Center

Bolster, L. Carey

1974-01-01

An activity is suggested which will give junior high school students practice in estimating and measuring in centimeters and millimeters. Three worksheets are given, one of which is a model for making a metric caliper. (LS)

Microfabricated Millimeter-Wave High-Power Vacuum Electronic Amplifiers

DTIC Science & Technology

2015-01-01

Applications filed 2012). In spite of the challenges, high power sources of electromagnetic radiation are needed in the mmW bands for advanced DoD...Research Laboratory is demonstrating and developing millimeter-wave vacuum electronic traveling wave tube amplifiers at W- and G- band in the 10’ s to 100... s of watts power range at several percent instantaneous bandwidth. Keywords: Traveling wave tube; millimeter wave; vacuum electron device

Real-time millimeter-wave imaging radiometer for avionic synthetic vision

NASA Astrophysics Data System (ADS)

Lovberg, John A.; Chou, Ri-Chee; Martin, Christopher A.

1994-07-01

ThermoTrex Corporation (TTC) has developed an imaging radiometer, the passive microwave camera (PMC), that uses an array of frequency-scanned antennas coupled to a multi-channel acousto-optic (Bragg cell) spectrum analyzer to form visible images of a scene through acquisition of thermal blackbody radiation in the millimeter-wave spectrum. The output of the Bragg cell is imaged by a standard video camera and passed to a computer for normalization and display at real-time frame rates. One application of this system could be its incorporation into an enhanced vision system to provide pilots with a clear view of the runway during fog and other adverse weather conditions. The unique PMC system architecture will allow compact large-aperture implementations because of its flat antenna sensor. Other potential applications include air traffic control, all-weather area surveillance, fire detection, and security. This paper describes the architecture of the TTC PMC and shows examples of images acquired with the system.

Millimeter wave detection of nuclear radiation: an alternative detection mechanism.

PubMed

Gopalsami, N; Chien, H T; Heifetz, A; Koehl, E R; Raptis, A C

2009-08-01

We present a nuclear radiation detection mechanism using millimeter waves as an alternative to conventional detection. It is based on the concept that nuclear radiation causes ionization of air and that if we place a dielectric material near the radiation source, it acts as a charge accumulator of the air ions. We have found that millimeter waves can interrogate the charge cloud on the dielectric material remotely. This concept was tested with a standoff millimeter wave system by monitoring the charge levels on a cardboard tube placed in an x-ray beam.

Superconducting Detector Arrays for Astrophysics

NASA Technical Reports Server (NTRS)

Chervenak, James

2008-01-01

The next generation of astrophysics instruments will feature an order of magnitude more photon sensors or sensors that have an order of magnitude greater sensitivity. Since detector noise scales with temperature, a number of candidate technologies have been developed that use the intrinsic advantages of detector systems that operate below 1 Kelvin. Many of these systems employ of the superconducting phenomena that occur in metals at these temperatures to build ultrasensitive detectors and low-noise, low-power readout architectures. I will present one such system in use today to meet the needs of the astrophysics community at millimeter and x-ray wavelengths. Our group at NASA in collaboration with Princeton, NIST, Boulder and a number of other groups is building large format arrays of superconducting transition edge sensors (TES) read out with multiplexed superconducting quantum interference devices (SQUID). I will present the high sensitivity we have achieved in multiplexed x-ray sensors with the TES technology and describe the construction of a 1000-sensor TES/SQUID array for microwave measurements. With our collaboration's deployment of a kilopixel TES array for 2 mm radiation at the Atacarna Cosmology Telescope in November 2007, we have first images of the lensed Cosmic Microwave Background at fine angular scales.

A silicon technology for millimeter-wave monolithic circuits

NASA Astrophysics Data System (ADS)

Stabile, P. J.; Rosen, A.

1984-12-01

A silicon millimeter-wave integrated-circuit (SIMMWIC) technology that includes high-energy ion implantation and pulsed-laser annealing, secondary ion mass spectrometry (SIMS) profile diagnostics, and novel wafer thinning has been developed. This technology has been applied to a SIMMWIC single-pole single-throw (SPST) switch and to IMPATT and p-i-n diode fabrication schemes. Thus, the SIMMWIC technology is a proven base for monolithic millimeter-wave sources and control circuit applications.

Leak Detection in Spacecraft Using a 64-Element Multiplexed Passive Array to Monitor Structure-Borne Noise

NASA Astrophysics Data System (ADS)

Holland, Stephen D.; Song, Jun-Ho; Chimenti, D. E.; Roberts, Ron

2006-03-01

We demonstrate an array sensor method intended to locate leaks in manned spacecraft using leak-generated, structure-borne ultrasonic noise. We have developed and tested a method for sensing and processing leak noise to reveal the leak location involving the use of a 64-element phased-array. Cross-correlations of ultrasonic noise waveforms from a leak into vacuum have been used with a phased-array analysis to find the direction from the sensor to the leak. This method measures the propagation of guided ultrasonic Lamb waves passing under the PZT array sensor in the spacecraft skin structure. This paper will describe the custom-designed array with integrated electronics, as well as the performance of the array in prototype applications. We show that this method can be used to successfully locate leaks to within a few millimeters on a 0.6-m square aluminum plate.

Millimeter Studies of Nearby Debris Disks

NASA Astrophysics Data System (ADS)

MacGregor, Meredith Ann

2017-03-01

At least 20% of nearby main sequence stars are known to be surrounded by disks of dusty material resulting from the collisional erosion of planetesimals, similar to asteroids and comets in our own Solar System. The material in these ‘debris disks’ is directly linked to the larger bodies, like planets, in the system through collisions and gravitational perturbations. Observations at millimeter wavelengths are especially critical to our understanding of these systems, since the large grains that dominate emission at these long wavelengths reliably trace the underlying planetesimal distribution. In this thesis, I have used state-of-the-art observations at millimeter wavelengths to address three related questions concerning debris disks and planetary system evolution: 1) How are wide-separation, substellar companions formed? 2) What is the physical nature of the collisional process in debris disks? And, 3) Can the structure and morphology of debris disks provide probes of planet formation and subsequent dynamical evolution? Using ALMA observations of GQ Lup, a pre-main sequence system with a wide-separation, substellar companion, I have placed constraints on the mass of a circumplanetary disk around the companion, informing formation scenarios for this and other similar systems (Chapter 2). I obtained observations of a sample of fifteen debris disks with both the VLA and ATCA at centimeter wavelengths, and robustly determined the millimeter spectral index of each disk and thus the slope of the grain size distribution, providing the first observational test of collision models of debris disks (Chapter 3). By applying an MCMC modeling framework to resolved millimeter observations with ALMA and SMA, I have placed the first constraints on the position, width, surface density gradient, and any asymmetric structure of the AU Mic, HD 15115, Epsilon Eridani, Tau Ceti, and Fomalhaut debris disks (Chapters 4–8). These observations of individual systems hint at trends in

Millimeter wave propagation measurements using the ATS 5 satellite

NASA Technical Reports Server (NTRS)

Ippolito, L. J.

1972-01-01

The ATS 5 millimeter wave propagation experiment determines long- and short-term attenuation statistics of operational millimeter wavelength earthspace links as functions of defined meteorological conditions. A preliminary analysis of results with 15 GHz downlink and 32 GHz uplink frequency bands indicates that both frequency bands exhibit an excellent potential for utilization in reliable high data rate earth-space communications systems.

Solar radiometry at millimeter wavelengths. [Fast Fourier Transformation solutions

NASA Technical Reports Server (NTRS)

Henze, W.

1974-01-01

In the area of resolution enhancement, the use of Fast Fourier Transform programs was investigated for possible application to millimeter wavelength maps of the sun. A difficulty arises with the La Posta maps in that they are limited to 35 arc-minutes square while the smeared out solar image is larger than that. A list of possible cometary emission lines near 13 millimeters is presented. Although preparation of the list was inspired by the appearance of Comet Kohoutek, the results are applicable to any future comet. The brightness temperature of the sun at 8.6 millimeters was measured using the moon as a calibration source. The result does not confirm a deep absorption feature as apparently observed by earlier workers.

Low-Cost Enclosure For The Sub-Millimeter Telescope

NASA Astrophysics Data System (ADS)

Ulich, Bobby L.; Hoffmann, William F.; Davison, Warren B.; Baars, Jacob W. M.; Mezger, Peter G.

1983-11-01

The University of Arizona and the Max-Planck-Institut fur Radioastronomie are collaborating to construct a sub-millimeter wavelength radio telescope facility at the summit of Mt. Lemmon (2791 m above sea level) near Tucson, Arizona. We have designed a corotating building to protect the 10 m diameter Sub-Millimeter Telescope (SMT) against storm damage, to provide large instrumentation rooms at the Nasmyth foci, and to minimize degradation of the reflector profile accuracy and pointing errors caused by wind forces and solar radiation.

Resolved Millimeter Observations of the HR 8799 Debris Disk

NASA Astrophysics Data System (ADS)

Wilner, David J.; MacGregor, Meredith A.; Andrews, Sean M.; Hughes, A. Meredith; Matthews, Brenda; Su, Kate

2018-03-01

We present 1.3 mm observations of the debris disk surrounding the HR 8799 multi-planet system from the Submillimeter Array to complement archival ALMA observations that spatially filtered away the bulk of the emission. The image morphology at 3.″8 (150 au) resolution indicates an optically thin circumstellar belt, which we associate with a population of dust-producing planetesimals within the debris disk. The interferometric visibilities are fit well by an axisymmetric radial power-law model characterized by a broad width, ΔR/R ≳ 1. The belt inclination and orientation parameters are consistent with the planet orbital parameters within the mutual uncertainties. The models constrain the radial location of the inner edge of the belt to {R}in}={104}-12+8 au. In a simple scenario where the chaotic zone of the outermost planet b truncates the planetesimal distribution, this inner edge location translates into a constraint on the planet b mass of {M}pl}={5.8}-3.1+7.9 M Jup. This mass estimate is consistent with infrared observations of the planet luminosity and standard hot-start evolutionary models, with the uncertainties allowing for a range of initial conditions. We also present new 9 mm observations of the debris disk from the Very Large Array and determine a millimeter spectral index of 2.41 ± 0.17. This value is typical of debris disks and indicates a power-law index of the grain size distribution q = 3.27 ± 0.10, close to predictions for a classical collisional cascade.

NOY: a neutrino observatory network project based on stand alone air shower detector arrays

NASA Astrophysics Data System (ADS)

Montanet, F.; Lebrun, D.; Chauvin, J.; Lagorio, E.; Stassi, P.

2011-09-01

We have developed a self powered stand alone particle detector array dedicated to the observation of horizontal tau air showers induced by high energy neutrinos interacting in mountain rock. Air shower particle detection reaches a 100% duty cycle and is practically free of background when compared to Cherenkov light or radio techniques. It is thus better suited for rare neutrino event search. An appropriate mountain to valley topological configuration has been identified and the first array will be deployed on an inclined slope at an elevation of 1500 m facing Southern Alps near the city of Grenoble (France). A full simulation has been performed. A neutrino energy dependent mountain tomography chart is obtained using a neutrino and tau propagation code together with a detailed cartography and elevation map of the region. The array acceptance is then evaluated between 1 PeV and 100 EeV by simulating decaying tau air showers across the valley. The effective detection surface is determined by the shower lateral extension at array location and is hence much larger than the array geometrical area. The array exposure will be 1014 cm2 sr s at 100 PeV. Several independent arrays can be deployed with the aim of constituting a large distributed observatory. Some other sites are already under study. At last, special care is dedicated to the educational and outreach aspects of such a cosmic ray detector.

Millimeter-wave micro-Doppler measurements of small UAVs

NASA Astrophysics Data System (ADS)

Rahman, Samiur; Robertson, Duncan A.

2017-05-01

This paper discusses the micro-Doppler signatures of small UAVs obtained from a millimeter-wave radar system. At first, simulation results are shown to demonstrate the theoretical concept. It is illustrated that whilst the propeller rotation rate of the small UAVs is quite high, millimeter-wave radar systems are capable of capturing the full micro-Doppler spread. Measurements of small UAVs have been performed with both CW and FMCW radars operating at 94 GHz. The CW radar was used for obtaining micro-Doppler signatures of individual propellers. The field test data of a flying small UAV was collected with the FMCW radar and was processed to extract micro-Doppler signatures. The high fidelity results clearly reveal features such as blade flashes and propeller rotation modulation lines which can be used to classify targets. This work confirms that millimeter-wave radar is suitable for the detection and classification of small UAVs at usefully long ranges.

Surveying Low-Mass Star Formation with the Submillimeter Array

NASA Astrophysics Data System (ADS)

Dunham, Michael

2018-01-01

Large astronomical surveys yield important statistical information that can’t be derived from single-object and small-number surveys. In this talk I will review two recent surveys in low-mass star formation undertaken by the Submillimeter Array (SMA): a millimeter continuum survey of disks surrounding variably accreting young stars, and a complete continuum and molecular line survey of all protostars in the nearby Perseus Molecular Cloud. I will highlight several new insights into the processes by which low-mass stars gain their mass that have resulted from the statistical power of these surveys.

Code-modulated interferometric imaging system using phased arrays

NASA Astrophysics Data System (ADS)

Chauhan, Vikas; Greene, Kevin; Floyd, Brian

2016-05-01

Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

Stray light suppression in the Goddard IRAM 2-Millimeter Observer (GISMO)

NASA Astrophysics Data System (ADS)

Sharp, E. H.; Benford, D. J.; Fixsen, D. J.; Moseley, S. H.; Staguhn, J. G.; Wollack, E. J.

2012-09-01

The Goddard-IRAM Superconducting 2 Millimeter Observer (GISMO) is an 8x16 Transition Edge Sensor (TES) array of bolometers built as a pathfinder for TES detector development efforts at NASA Goddard Space Flight Center. GISMO has been used annually at the Institut de Radioastronomie Millimétrique (IRAM) 30 meter telescope since 2007 under engineering time and was opened in the spring of 2012 to the general astronomical community. The spring deployment provided an opportunity to modify elements of the room temperature optics before moving the instrument to its new permanent position in the telescope receiver cabin. This allowed for the possibility to extend the cryostat, introduce improved cold baffling and thus further optimize the stray light performance for final astronomical use of the instrument, which has been completed and validated. We will demonstrate and discuss several of the methods used to quantify and limit the influence of stray light in the GISMO camera.

Stray Light Suppression in the Goddard IRAM 2-Millimeter Observer (GISMO)

NASA Technical Reports Server (NTRS)

Sharp, E. H.; Benford, D. J.; Fixsen, D. J.; Moseley, S. H.; Staguhn, J. G.; Wollack, E. J.

2012-01-01

The Goddard-IRAM Superconducting 2 Millimeter Observer (GISMO) is an 8xl6 Transition Edge Sensor (TES) array of bolometers built as a pathfinder for TES detector development efforts at NASA Goddard Space Flight Center. GISMO has been used annually at the Institut de Radioastronomie Millimetrique (IRAM) 30 meter telescope since 2007 under engineering time and was opened in the spring of 2012 to the general astronomical community. The spring deployment provided an opportunity to modify elements of the room temperature optics before moving the instrument to its new permanent position in the telescope receiver cabin. This allowed for the possibility to extend the cryostat, introduce improved cold baffling and thus further optimize the stray light performance for final astronomical use of the instrument, which has been completed and validated. We will demonstrate and discuss several of the methods used to quantify and limit the influence of stray light in the GISMO camera.

Design of a 2-mm Wavelength KIDs Prototype Camera for the Large Millimeter Telescope

NASA Astrophysics Data System (ADS)

Velázquez, M.; Ferrusca, D.; Castillo-Dominguez, E.; Ibarra-Medel, E.; Ventura, S.; Gómez-Rivera, V.; Hughes, D.; Aretxaga, I.; Grant, W.; Doyle, S.; Mauskopf, P.

2016-08-01

A new camera is being developed for the Large Millimeter Telescope (Sierra Negra, México) by an international collaboration with the University of Massachusetts, the University of Cardiff, and Arizona State University. The camera is based on kinetic inductance detectors (KIDs), a very promising technology due to their sensitivity and especially, their compatibility with frequency domain multiplexing at microwave frequencies allowing large format arrays, in comparison with other detection technologies for mm-wavelength astronomy. The instrument will have a 100 pixels array of KIDs to image the 2-mm wavelength band and is designed for closed cycle operation using a pulse tube cryocooler along with a three-stage sub-kelvin 3He cooler to provide a 250 mK detector stage. RF cabling is used to readout the detectors from room temperature to 250 mK focal plane, and the amplification stage is achieved with a low-noise amplifier operating at 4 K. The readout electronics will be based on open-source reconfigurable open architecture computing hardware in order to perform real-time microwave transmission measurements and monitoring the resonance frequency of each detector, as well as the detection process.

Millimeter wavelength observations of solar active regions

NASA Technical Reports Server (NTRS)

Kundu, M. R.

1973-01-01

Polarization properties of active regions at 9 mm are discussed, and the observed degree of polarization is used to obtain an estimate of chromospheric magnetic fields. Also discussed is the polarization structure at 9 mm of an active region that produced a minor flare around 1900 UT on September 28, 1971. Total power observations indicate that new regions develop, or weak regions intensify at millimeter wavelengths as a result of bursts at distant sites. The spectra of the peak flux density of moderately strong bursts observed at 9 mm show a sharp drop toward the shorter millimeter wavelengths. The weak bursts at 3.5 mm are manifest mainly as heating phenomena.

Sub-millimeter science with the Heinrich-Hertz-Telescope

NASA Astrophysics Data System (ADS)

Dumke, Michael

The Heinrich-Hertz-Telescope on Mt. Graham, Arizona, is a state-of-the-art single-dish radio telescope for observations in the sub-millimeter wavelength range. It is operated by the Sub-Millimeter Telescope Observatory (SMTO), which is a collaboration between the University of Arizona, Tucson, and the Max-Planck-Institut für Radioastronomie, Bonn. In this talk I give an overview over the telescope and its instrumentation, and show some examples of forefront research performed by astronomers from both the U.S. and Europe using this instrument. The telescope is located on Mt. Graham, Arizona, at an altitude of 3178 m, which ensures sub-mm weather conditions during a significant amount of available observing time. It has a primary reflector of 10 m diameter, mounted on a carbon fiber backup structure, and is equipped with a corotating enclosure. The surface accuracy of the primary reflector is 12 microns rms, what makes the HHT the most accurate radio telescope ever built. For spectral line observations, SIS receivers covering the frequency range from 200 to 500 GHz are available. Furthermore, a Hot-Electron-Bolometer, developed at the CfA, can be used for spectral line observations above 800 GHz. The continuum receivers are a 4-color bolometer, observing at 1300, 870, 450, and 350 microns, and a 19-channel bolometer array, developed at the MPIfR, which is sensitive around 850 microns. In the last few years, the HHT has been used by several groups to perform astronomical research. The most notable result was the measurement of the CO(9--8) line in Orion at 1.037 THz with the Hot-Electron Bolometer -- the first radioastronomical observation above 1 THz from a ground-based telescope. Several galactic molecular line sources have been mapped in the CO(7--6) line at 806 GHz, and in two fine-structure lines of atomic carbon. A continuum map of the galactic center at 850 microns could be produced using the new 19-channel bolometer array. Even external galaxies, where

Millimeter-wave generation and characterization of a GaAs FET by optical mixing

NASA Technical Reports Server (NTRS)

Ni, David C.; Fetterman, Harold R.; Chew, Wilbert

1990-01-01

Coherent mixing of optical radiation from a tunable continuous-wave dye laser and a stabilized He-Ne laser was used to generate millimeter-wave signals in GaAs FETs attached to printed-circuit millimeter-wave antennas. The generated signal was further down-converted to a 2-GHz IF by an antenna-coupled millimeter-wave local oscillator at 62 GHz. Detailed characterizations of power and S/N under different bias conditions have been performed. This technique is expected to allow signal generation and frequency-response evaluation of millimeter-wave devices at frequencies as high as 100 GHz.

Full colorless transmission of millimeter-wave band gigabit data over WDM-PON using sideband routing

NASA Astrophysics Data System (ADS)

Won, Yong-Yuk; Kim, Hyun-Seung; Son, Yong-Hwan; Han, Sang-Kook

2011-12-01

A new wavelength division multiplexed-radio over fiber (WDM-RoF) access network scheme supporting the simultaneous transmission of a 1.25-Gb/s wired data as well as a 1.25-Gb/s wireless data is proposed in this paper. An optical carrier suppression effect and sideband routing using the multiplexing of arrayed waveguide grating (AWG) with 50-GHz channel spacing are utilized to generate a millimeter wave band carrier. These techniques make the proposed architecture transmit both a wired data and a wireless one at the same time. A reflective semiconductor optical amplifier (RSOA) is employed at both central office and base station so that this architecture is operated colorlessly. Error free transmissions (BER of 10-9) of both downlink and uplink are achieved simultaneously.

Wide extragalactic (sub-)millimeter surveys with SCUBA and AzTEC

NASA Astrophysics Data System (ADS)

Aretxaga, I.; Hughes, D. H.; SHADES Collaboration; AzTEC Collaboration

2009-05-01

We summarize the present status of our knowledge of the millimeter galaxy population derived from extensive (sub-) millimeter extragalactic surveys like the SCUBA HAlf Degree Survey (SHADES), and the current status of the next generation of surveys traced with the AzTEC camera, that has, so far, surveyed more than 2 degrees at 1.1wavelengths.

Millimeter and X-Ray Emission from the 5 July 2012 Solar Flare

NASA Astrophysics Data System (ADS)

Tsap, Y. T.; Smirnova, V. V.; Motorina, G. G.; Morgachev, A. S.; Kuznetsov, S. A.; Nagnibeda, V. G.; Ryzhov, V. S.

2018-03-01

The 5 July 2012 solar flare SOL2012-07-05T11:44 (11:39 - 11:49 UT) with an increasing millimeter spectrum between 93 and 140 GHz is considered. We use space and ground-based observations in X-ray, extreme ultraviolet, microwave, and millimeter wave ranges obtained with the Reuven Ramaty High-Energy Solar Spectroscopic Imager, Solar Dynamics Observatory (SDO), Geostationary Operational Environmental Satellite, Radio Solar Telescope Network, and Bauman Moscow State Technical University millimeter radio telescope RT-7.5. The main parameters of thermal and accelerated electrons were determined through X-ray spectral fitting assuming the homogeneous thermal source and thick-target model. From the data of the Atmospheric Imaging Assembly/SDO and differential-emission-measure calculations it is shown that the thermal coronal plasma gives a negligible contribution to the millimeter flare emission. Model calculations suggest that the observed increase of millimeter spectral flux with frequency is determined by gyrosynchrotron emission of high-energy (≳ 300 keV) electrons in the chromosphere. The consequences of the results are discussed in the light of the flare-energy-release mechanisms.

Large micromirror array for multi-object spectroscopy in space

NASA Astrophysics Data System (ADS)

Canonica, Michael; Zamkotsian, Frédéric; Lanzoni, Patrick; Noell, Wilfried

2017-11-01

Multi-object spectroscopy (MOS) is a powerful tool for space and ground-based telescopes for the study of the formation and evolution of galaxies. This technique requires a programmable slit mask for astronomical object selection. We are engaged in a European development of micromirror arrays (MMA) for generating reflective slit masks in future MOS, called MIRA. The 100 x 200 μm2 micromirrors are electrostatically tilted providing a precise angle. The main requirements are cryogenic environment capabilities, precise and uniform tilt angle over the whole device, uniformity of the mirror voltage-tilt hysteresis and a low mirror deformation. A first MMA with single-crystal silicon micromirrors was successfully designed, fabricated and tested. A new generation of micromirror arrays composed of 2048 micromirrors (32 x 64) and modelled for individual addressing were fabricated using fusion and eutectic wafer-level bonding. These micromirrors without coating show a peak-to-valley deformation less than 10 nm, a tilt angle of 24° for an actuation voltage of 130 V. Individual addressing capability of each mirror has been demonstrated using a line-column algorithm based on an optimized voltage-tilt hysteresis. Devices are currently packaged, wire-bonded and integrated to a dedicated electronics to demonstrate the individual actuation of all micromirrors on an array. An operational test of this large array with gold coated mirrors has been done at cryogenic temperature (162 K): the micromirrors were actuated successfully before, during and after the cryogenic experiment. The micromirror surface deformation was measured at cryo and is below 30 nm peak-to-valley.

Microwave and millimeter-wave resonant tunneling diodes

NASA Technical Reports Server (NTRS)

Sollner, T. C. L. Gerhard; Brown, Elliott R.; Goodhue, W. D.

1987-01-01

Several demonstrated resonant tunneling devices including oscillators, mixers, multiplexers, and a variable negative resistance are discussed. Techniques of the millimeter/submillimeter regime are also discussed.

Investigation of passive atmospheric sounding using millimeter and submillimeter wavelength channels

NASA Technical Reports Server (NTRS)

Gasiewski, Albin J.; Adelberg, L. K.; Kunkee, D. B.; Jackson, D. M.

1993-01-01

Activities within the period from July 1, 1992 through December 31, 1992 by Georgia Tech researchers in millimeter and submillimeter wavelength tropospheric remote sensing have been centered around the calibration of the Millimeter-wave Imaging Radiometer (MIR), preliminary flight data analysis, and preparation for TOGA/COARE. The MIR instrument is a joint project between NASA/GSFC and Georgia Tech. In the current configuration, the MIR has channels at 90, 150, 183(+/-1,3,7), and 220 GHz. Provisions for three additional channels at 325(+/-1,3) and 8 GHz have been made, and a 325-GHz receiver is currently being built by the ZAX Millimeter Wave Corporation for use in the MIR. Past Georgia Tech contributions to the MIR and its related scientific uses have included basic system design studies, performance analyses, and circuit and radiometric load design, in-flight software, and post-flight data display software. The combination of the above millimeter wave and submillimeter wave channels aboard a single well-calibrated instrument will provide unique radiometric data for radiative transfer and cloud and water vapor retrieval studies. A paper by the PI discussing the potential benefits of passive millimeter and submillimeter wave observations for cloud, water vapor and precipitation measurements has recently been published, and is included as an appendix.

Bolometric kinetic inductance detector technology for sub-millimeter radiometric imaging

NASA Astrophysics Data System (ADS)

Hassel, Juha; Timofeev, Andrey V.; Vesterinen, Visa; Sipola, Hannu; Helistö, Panu; Aikio, Mika; Mäyrä, Aki; Grönberg, Leif; Luukanen, Arttu

2015-10-01

Radiometric sub-millimeter imaging is a candidate technology especially in security screening applications utilizing the property of radiation in the band of 0.2 - 1.0 THz to penetrate through dielectric substances such as clothing. The challenge of the passive technology is the fact that the irradiance corresponding to the blackbody radiation is very weak in this spectral band: about two orders of magnitude below that of the infrared band. Therefore the role of the detector technology is of ultimate importance to achieve sufficient sensitivity. In this paper we present results related to our technology relying on superconducting kinetic inductance detectors operating in a thermal (bolometric) mode. The detector technology is motivated by the fact that it is naturally suitable for scalable multiplexed readout systems, and operates with relatively simple cryogenics. We will review the basic concepts of the detectors, and provide experimental figures of merit. Furthermore, we will discuss the issues related to the scale-up of our detector technology into large 2D focal plane arrays.

MIMIC For Millimeter Wave Integrated Circuit Radars

NASA Astrophysics Data System (ADS)

Seashore, C. R.

1987-09-01

A significant program is currently underway in the U.S. to investigate, develop and produce a variety of GaAs analog circuits for use in microwave and millimeter wave sensors and systems. This represents a "new wave" of RF technology which promises to significantly change system engineering thinking relative to RF Architectures. At millimeter wave frequencies, we look forward to a relatively high level of critical component integration based on MESFET and HEMT device implementations. These designs will spawn more compact RF front ends with colocated antenna/transceiver functions and innovative packaging concepts which will survive and function in a typical military operational environment which includes challenging temperature, shock and special handling requirements.

Millimeter wave sensor for monitoring effluents

DOEpatents

Gopalsami, Nachappa; Bakhtiari, Sasan; Raptis, Apostolos C.; Dieckman, Stephen L.

1995-01-01

A millimeter-wave sensor for detecting and measuring effluents from processing plants either remotely or on-site includes a high frequency signal source for transmitting frequency-modulated continuous waves in the millimeter or submillimeter range with a wide sweep capability and a computer-controlled detector for detecting a plurality of species of effluents on a real time basis. A high resolution spectrum of an effluent, or effluents, is generated by a deconvolution of the measured spectra resulting in a narrowing of the line widths by 2 or 3 orders of magnitude as compared with the pressure broadened spectra detected at atmospheric pressure for improved spectral specificity and measurement sensitivity. The sensor is particularly adapted for remote monitoring such as where access is limited or sensor cost restricts multiple sensors as well as for large area monitoring under nearly all weather conditions.

Site response, shallow shear-wave velocity, and wave propagation at the San Jose, California, dense seismic array

USGS Publications Warehouse

Hartzell, S.; Carver, D.; Williams, R.A.; Harmsen, S.; Zerva, A.

2003-01-01

Ground-motion records from a 52-element dense seismic array near San Jose, California, are analyzed to obtain site response, shallow shear-wave velocity, and plane-wave propagation characteristics. The array, located on the eastern side of the Santa Clara Valley south of the San Francisco Bay, is sited over the Evergreen basin, a 7-km-deep depression with Miocene and younger deposits. Site response values below 4 Hz are up to a factor of 2 greater when larger, regional records are included in the analysis, due to strong surface-wave development within the Santa Clara Valley. The pattern of site amplification is the same, however, with local or regional events. Site amplification increases away from the eastern edge of the Santa Clara Valley, reaching a maximum over the western edge of the Evergreen basin, where the pre-Cenozoic basement shallows rapidly. Amplification then decreases further to the west. This pattern may be caused by lower shallow shear-wave velocities and thicker Quaternary deposits further from the edge of the Santa Clara Valley and generation/trapping of surface waves above the shallowing basement of the western Evergreen basin. Shear-wave velocities from the inversion of site response spectra based on smaller, local earthquakes compare well with those obtained independently from our seismic reflection/refraction measurements. Velocities from the inversion of site spectra that include larger, regional records do not compare well with these measurements. A mix of local and regional events, however, is appropriate for determination of site response to be used in seismic hazard evaluation, since large damaging events would excite both body and surface waves with a wide range in ray parameters. Frequency-wavenumber, plane-wave analysis is used to determine the backazimuth and apparent velocity of coherent phases at the array. Conventional, high-resolution, and multiple signal characterization f-k power spectra and stacked slowness power spectra are

Evaluation of a SiPM array coupled to a Gd3Al2Ga3O12:Ce (GAGG:Ce) discrete scintillator.

PubMed

David, S; Georgiou, M; Fysikopoulos, E; Loudos, G

2015-11-01

In this study, we present the results of the evaluation of the SensL ArraySL-4 photo-detector, coupled to a 6 × 6 GAGG:Ce scintillator array, with 2 × 2 × 5 mm(3) crystal size elements for possible applications in medical imaging detectors with focus in PET applications. Experimental evaluation was carried out with (22)Na and (137)Cs radioactive sources and the parameters studied were energy resolution and peak to valley ratio. ArraySL-4 is a commercially available, 4 × 4 array detector covering an active area of 13.4 mm(2). The GAGG:Ce scintillator array used in this study has 0.1 mm thickness BaSO4 reflector material between the crystal elements. A symmetric resistive voltage division matrix was applied, which reduces the 16 outputs of the array to 4 position signals. A Field Programmable Gate Array was used for triggering and digital processing of the signal pulses acquired using free running Analog to Digital Converters. Raw images and horizontal profiles of the 6 × 6 GAGG:Ce scintillator array produced under 511 keV and 662 keV excitation are illustrated. Moreover, the energy spectra obtained with (22)Na and (137)Cs radioactive sources from a single 2 × 2 × 5 mm(3) GAGG:Ce scintillator are shown. The peak to valley ratio and the mean energy resolution values are reported. The acquired raw image of the GAGG:Ce crystal array under 511 keV excitation shows a clear visualization of all discrete scintillator elements with a mean peak to valley ratio equal to 40. The mean energy resolution was measured equal to 10.5% and 9% respectively under 511 keV and 662 keV irradiation. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Valley-dependent band structure and valley polarization in periodically modulated graphene

NASA Astrophysics Data System (ADS)

Lu, Wei-Tao

2016-08-01

The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

Tunable ferromagnetic resonance in La-Co substituted barium hexaferrites at millimeter wave frequencies

NASA Astrophysics Data System (ADS)

Korolev, Konstantin A.; Wu, Chuanjian; Yu, Zhong; Sun, Ke; Afsar, Mohammed N.; Harris, Vincent G.

2018-05-01

Transmittance measurements have been performed on La-Co substituted barium hexaferrites in millimeter waves. Broadband millimeter-wave measurements have been carried out using the free space quasi-optical spectrometer, equipped with a set of high power backward wave oscillators covering the frequency range of 30 - 120 GHz. Strong absorption zones have been observed in the millimeter-wave transmittance spectra of all La-Co substituted barium hexaferrites due to the ferromagnetic resonance. Linear shift of ferromagnetic resonance frequency as functions of La-Co substitutions have been found. Real and imaginary parts of dielectric permittivity of La-Co substituted barium hexaferrites have been calculated using the analysis of recorded high precision transmittance spectra. Frequency dependences of magnetic permeability of La-Co substituted barium hexaferrites, as well as saturation magnetization and anisotropy field have been determined based on Schlömann's theory for partially magnetized ferrites. La-Co substituted barium hexaferrites have been further investigated by DC magnetization to assess magnetic behavior and compare with millimeter wave data. Consistency of saturation magnetization determined independently by both millimeter wave absorption and DC magnetization have been found for all La-Co substituted barium hexaferrites. These materials seem to be quite promising as tunable millimeter wave absorbers, filters, circulators, based on the adjusting of their substitution parameters.

Advancements in Kinetic Inductance Detector, Spectrometer, and Amplifier Technologies for Millimeter-Wave Astronomy

NASA Astrophysics Data System (ADS)

Che, George

The inductance of a conductor expresses its tendency to oppose a change in current flowing through it. For superconductors, in addition to the familiar magnetic inductance due to energy stored in the magnetic field generated by this current, kinetic inductance due to inertia of charge carriers is a significant and often dominant contribution to total inductance. Devices based on modifying the kinetic inductance of thin film superconductors have widespread application to millimeter-wave astronomy. Lithographically patterning such a film into a high quality factor resonator produces a high sensitivity photodetector known as a kinetic inductance detector (KID), which is sensitive to frequencies above the superconducting energy gap of the chosen material. Inherently multiplexable in the frequency domain and relatively simple to fabricate, KIDs pave the way to the large format focal plane array instruments necessary to conduct the next generation of cosmic microwave background (CMB), star formation, and galaxy evolution studies. In addition, non-linear kinetic inductance can be exploited to develop traveling wave kinetic inductance parametric amplifiers (TKIPs) based on superconducting delay lines to read out these instruments. I present my contributions to both large and small scale collaborative efforts to develop KID arrays, spectrometers integrated with KIDs, and TKIPs. I optimize a dual polarization TiN KID absorber for the next generation Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry, which is designed to investigate the role magnetic fields play in star formation. As part of an effort to demonstrate aluminum KIDs on sky for CMB polarimetry, I fabricate devices for three design variants. SuperSpec and WSpec are respectively the on-chip and waveguide implementations of a filter bank spectrometer concept designed for survey spectroscopy of high redshift galaxies. I provide a robust tool for characterizing the performance of all Super

Chirped-Pulse Millimeter-Wave Spectroscopy of Rydberg-Rydberg Transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prozument, Kirill; Colombo, Anthony P.; Zhou Yan

2011-09-30

Transitions between Rydberg states of Ca atoms, in a pulsed, supersonic atomic beam, are directly detected by chirped-pulse millimeter-wave spectroscopy. Broadband, high-resolution spectra with accurate relative intensities are recorded instantly. Free induction decay (FID) of atoms, polarized by the chirped pulse, at their Rydberg-Rydberg transition frequencies, is heterodyne detected, averaged in the time domain, and Fourier transformed into the frequency domain. Millimeter-wave transient nutations are observed, and the possibility of FID evolving to superradiance is discussed.

Plasmonic phased array feeder enabling ultra-fast beam steering at millimeter waves.

PubMed

Bonjour, R; Burla, M; Abrecht, F C; Welschen, S; Hoessbacher, C; Heni, W; Gebrewold, S A; Baeuerle, B; Josten, A; Salamin, Y; Haffner, C; Johnston, P V; Elder, D L; Leuchtmann, P; Hillerkuss, D; Fedoryshyn, Y; Dalton, L R; Hafner, C; Leuthold, J

2016-10-31

In this paper, we demonstrate an integrated microwave phoneeded for beamtonics phased array antenna feeder at 60 GHz with a record-low footprint. Our design is based on ultra-compact plasmonic phase modulators (active area <2.5µm²) that not only provide small size but also ultra-fast tuning speed. In our design, the integrated circuit footprint is in fact only limited by the contact pads of the electrodes and by the optical feeding waveguides. Using the high speed of the plasmonic modulators, we demonstrate beam steering with less than 1 ns reconfiguration time, i.e. the beam direction is reconfigured in-between 1 GBd transmitted symbols.

Antenna-coupled TES bolometer arrays for CMB polarimetry

NASA Astrophysics Data System (ADS)

Kuo, C. L.; Bock, J. J.; Bonetti, J. A.; Brevik, J.; Chattopadhyay, G.; Day, P. K.; Golwala, S.; Kenyon, M.; Lange, A. E.; LeDuc, H. G.; Nguyen, H.; Ogburn, R. W.; Orlando, A.; Transgrud, A.; Turner, A.; Wang, G.; Zmuidzinas, J.

2008-07-01

We describe the design and performance of polarization selective antenna-coupled TES arrays that will be used in several upcoming Cosmic Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully lithographic polarimeter arrays utilize planar phased-antennas for collimation (F/4 beam) and microstrip filters for band definition (25% bandwidth). These devices demonstrate high optical efficiency, excellent beam shapes, and well-defined spectral bands. The dual-polarization antennas provide well-matched beams and low cross polarization response, both important for high-fidelity polarization measurements. These devices have so far been developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave atmospheric windows for CMB observations. In the near future, the flexible microstrip-coupled architecture can provide photon noise-limited detection for the entire frequency range of the CMBPOL mission. This paper is a summary of the progress we have made since the 2006 SPIE meeting in Orlando, FL.

Millimeter-scale MEMS enabled autonomous systems: system feasibility and mobility

NASA Astrophysics Data System (ADS)

Pulskamp, Jeffrey S.

2012-06-01

Millimeter-scale robotic systems based on highly integrated microelectronics and micro-electromechanical systems (MEMS) could offer unique benefits and attributes for small-scale autonomous systems. This extreme scale for robotics will naturally constrain the realizable system capabilities significantly. This paper assesses the feasibility of developing such systems by defining the fundamental design trade spaces between component design variables and system level performance parameters. This permits the development of mobility enabling component technologies within a system relevant context. Feasible ranges of system mass, required aerodynamic power, available battery power, load supported power, flight endurance, and required leg load bearing capability are presented for millimeter-scale platforms. The analysis illustrates the feasibility of developing both flight capable and ground mobile millimeter-scale autonomous systems while highlighting the significant challenges that must be overcome to realize their potential.

Millimeter-wave technology advances since 1985 and future trends

NASA Astrophysics Data System (ADS)

Meinel, Holger H.

1991-05-01

The author focuses on finline or E-plane technology. Several examples, including AVES, a 61.5-GHz radar sensor for traffic data acquisition, are included. Monolithic integrated 60- and 94-GHz receiver circuits composed of a mixer and IF amplifier in compatible FET technology on GaAs are presented to show the state of the art in this area. A promising approach to the use of silicon technology for monolithic millimeter-wave integrated circuits, called SIMMWIC, is described as well. As millimeter-wave technology has matured, increased interest has been generated for very specific applications: (1) commercial automotive applications such as intelligent cruise control and enhanced vision have attracted great interest, calling for a low-cost design approach; and (2) an almost classical application of millimeter-wave techniques is the field of radar seekers, e.g., for intelligent ammunitions, calling for high performance under extreme environmental conditions. Two examples fulfilling these requirements are described.

Millimeter-wave and terahertz integrated circuit antennas

NASA Technical Reports Server (NTRS)

Rebeiz, Gabriel M.

1992-01-01

This paper presents a comprehensive review of integrated circuit antennas suitable for millimeter and terahertz applications. A great deal of research was done on integrated circuit antennas in the last decade and many of the problems associated with electrically thick dielectric substrates, such as substrate modes and poor radiation patterns, have been understood and solved. Several new antennas, such as the integrated horn antenna, the dielectric-filled parabola, the Fresnel plate antenna, the dual-slot antenna, and the log-periodic and spiral antennas on extended hemispherical lenses, have resulted in excellent performance at millimeter-wave frequencies, and are covered in detail in this paper. Also, a review of the efficiency definitions used with planar antennas is given in detail in the appendix.

Hierarchical Phased Array Antenna Focal Plane for Cosmic Microwave Background Polarization and Sub-mm Observations

NASA Astrophysics Data System (ADS)

Lee, Adrian

We propose to develop planar-antenna-coupled superconducting bolometer arrays for observations at sub-millimeter to millimeter wavelengths. Our pixel architecture features a dual-polarization, log-periodic antenna with a 5:1 bandwidth ratio, followed by a filter bank that divides the total bandwidth into several broad photometric bands. We propose to develop an hierarchical phased array of our basic pixel type that gives optimal mapping speed (sensitivity) over a much broader range of frequencies. The advantage of this combination of an intrinsically broadband pixel with hierarchical phase arraying include a combination of greatly reduced focal-plane mass, higher array sensitivity, and a larger number of spectral bands compared to focal-plane designs using conventional single-color pixels. These advantages have the potential to greatly reduce cost and/or increase performance of NASA missions in the sub-millimeter to millimeter bands. For CMB polarization, a wide frequency range of about 30 to 400 GHz is required to subtract galactic foregrounds. As an example, the multichroic architecture we propose could reduce the focal plane mass of the EPIC-IM CMB polarization mission study concept by a factor of 4, with great savings in required cryocooler performance and therefore cost. We have demonstrated the lens-coupled antenna concept in the POLARBEAR groundbased CMB polarization experiment which is now operating in Chile. That experiment uses a single-band planar antenna that gives excellent beam properties and optical efficiency. POLARBEAR recently succeeded in detecting gravitational lensing B-modes in the CMB polarization. In the laboratory, we have measured two octaves of total bandwidth in the log-periodic sinuous antenna. We have built filter banks of 2, 3, and 7 bands with 4, 6, and 14 bolometers per pixel for two linear polarizations. Pixels of this type are slated to be deployed on the ground in POLARBEAR and SPT-3G and proposed to be used on a balloon by EBEX

Farming Systems and Rural Out-Migration in Nang Rong, Thailand, and Chitwan Valley, Nepal

ERIC Educational Resources Information Center

Piotrowski, Martin; Ghimire, Dirgha; Rindfuss, Ronald

2013-01-01

Using data from two postfrontier rural settings, Nang Rong, Thailand (N = 2,538), and Chitwan Valley, Nepal (N = 876), this article examines agricultural push factors determining the out-migration of young people age 15 to 19. We focus on different dimensions of migration, including distance and duration. Our study examines a wide array of…

Indium Hybridization of Large Format TES Bolometer Arrays to Readout Multiplexers for Far-Infrared Astronomy

NASA Technical Reports Server (NTRS)

Miller, Timothy M.; Costen, Nick; Allen, Christine

2007-01-01

The advance of new detector technologies combined with enhanced fabrication methods has resulted in an increase in development of large format arrays. The next generation of scientific instruments will utilize detectors containing hundreds to thousands of elements providing a more efficient means to conduct large area sky surveys. Some notable detectors include a 32x32 x-ray microcalorimeter for Constellation-X, an infrared bolometer called SAFIRE to fly on the airborne observatory SOFIA, and the sub-millimeter bolometer SCUBA-2 to be deployed at the JCMT which will use more than 10,000 elements for two colors, each color using four 32x40 arrays. Of these detectors, SCUBA-2 is farthest along in development and uses indium hybridization to multiplexers for readout of the large number of elements, a technology that will be required to enable the next generation of large format arrays. Our current efforts in working toward large format arrays have produced GISMO, the Goddard IRAM Superconducting 2-Millimeter observer. GISMO is a far infrared instrument to be field tested later this year at the IRAM 30 meter telescope in Spain. GISMO utilizes transition edge sensor (TES) technology in an 8x16 filled array format that allows for typical fan-out wiring and wire-bonding to four 1x32 NIST multiplexers. GISMO'S electrical wiring is routed along the tops of 30 micron walls which also serve as the mechanical framework for the array. This architecture works well for the 128 element array, but is approaching the limit for routing the necessary wires along the surface while maintaining a high fill factor. Larger format arrays will benefit greatly from making electrical connections through the wafer to the backside, where they can be hybridized to a read-out substrate tailored to handling the wiring scheme. The next generation array we are developing is a 32x40 element array on a pitch of 1135 microns that conforms to the NIST multiplexer, already developed for the SCUBA-2

Research on metal-plated cellulose nitrate flakes and their infrared / millimeter wave characteristics

NASA Astrophysics Data System (ADS)

Ye, Shu-qin; Zhu, Chen-guang; Wang, Li-hong; Ou'yang, De-hua; Pan, Gong-pei

2016-10-01

Copper-plated and silver-plated cellulose nitrate flakes, which were prepared by using chemical plating technology, were used to jam infrared detector and millimeter-wave radar. It was tested for the conductivity and infrared jamming performance of plating and also the RCS (Radar Cross Section) performance of millimeter-wave radar. Test results showed that the prepared metal-plated cellulose nitrate flakes have obvious conductivity, and infrared total radiation energy of silver plating and copper plating had approximately increased 32% and 21% respectively. Through determination, the millimeter-wave reflecting property and RCS of silver-plated cellulose nitrate flakes were higher than that of copper-plated cellulose nitrate flakes. Therefore, silver-plated cellulose nitrate flakes can be used as an effective infrared / millimeter wave composite jamming material.

Primary Dendrite Array: Observations from Ground-Based and Space Station Processed Samples

NASA Technical Reports Server (NTRS)

Tewari, Surendra N.; Grugel, Richard N.; Erdman, Robert G.; Poirier, David R.

2012-01-01

Influence of natural convection on primary dendrite array morphology during directional solidification is being investigated under a collaborative European Space Agency-NASA joint research program, Microstructure Formation in Castings of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST). Two Aluminum-7 wt pct Silicon alloy samples, MICAST6 and MICAST7, were directionally solidified in microgravity on the International Space Station. Terrestrially grown dendritic monocrystal cylindrical samples were remelted and directionally solidified at 18 K per centimeter (MICAST6) and 28 K per centimeter (MICAST7). Directional solidification involved a growth speed step increase (MICAST6-from 5 to 50 millimeters per second) and a speed decrease (MICAST7-from 20 to 10 millimeters per second). Distribution and morphology of primary dendrites is currently being characterized in these samples, and also in samples solidified on earth under nominally similar thermal gradients and growth speeds. Primary dendrite spacing and trunk diameter measurements from this investigation will be presented.

A millimeter-wave reflection-beam isolator

NASA Technical Reports Server (NTRS)

Kanda, M.; May, W. G.

1975-01-01

A new and simple type of millimeter-wave isolator using a solid-state magnetoplasma in a reflection-beam system is described. Some data are presented showing performance at 94 GHz. Practical considerations indicate that performance should be much closer to ideal at higher frequencies.

Development of a contrast phantom for active millimeter-wave imaging systems

NASA Astrophysics Data System (ADS)

Barber, Jeffrey; Weatherall, James C.; Brauer, Carolyn S.; Smith, Barry T.

2011-06-01

As the development of active millimeter wave imaging systems continues, it is necessary to validate materials that simulate the expected response of explosives. While physics-based models have been used to develop simulants, it is desirable to image both the explosive and simulant together in a controlled fashion in order to demonstrate success. To this end, a millimeter wave contrast phantom has been created to calibrate image grayscale while controlling the configuration of the explosive and simulant such that direct comparison of their respective returns can be performed. The physics of the phantom are described, with millimeter wave images presented to show successful development of the phantom and simulant validation at GHz frequencies.

Large array of 2048 tilting micromirrors for astronomical spectroscopy: optical and cryogenic characterization

NASA Astrophysics Data System (ADS)

Zamkotsian, Frédéric; Canonica, Michael; Lanzoni, Patrick; Noell, Wilfried; Lani, Sebastien

2014-03-01

Multi-object spectroscopy (MOS) is a powerful tool for space and ground-based telescopes for the study of the formation and evolution of galaxies. This technique requires a programmable slit mask for astronomical object selection. We are engaged in a European development of micromirror arrays (MMA) for generating reflective slit masks in future MOS, called MIRA. MMA with 100 × 200 μm2 single-crystal silicon micromirrors were successfully designed, fabricated and tested. Arrays are composed of 2048 micromirrors (32 x 64) with a peak-to-valley deformation less than 10 nm, a tilt angle of 24° for an actuation voltage of 130 V. The micromirrors were actuated successfully before, during and after cryogenic cooling, down to 162K. The micromirror surface deformation was measured at cryo and is below 30 nm peak-to-valley. These performances demonstrate the ability of such MOEMS device to work as objects selector in future generation of MOS instruments both in ground-based and space telescopes. In order to fill large focal planes (mosaicing of several chips), we are currently developing large micromirror arrays integrated with their electronics.

Urban seismology - Northridge aftershocks recorded by multi-scale arrays of portable digital seismographs

USGS Publications Warehouse

Meremonte, M.; Frankel, A.; Cranswick, E.; Carver, D.; Worley, D.

1996-01-01

We deployed portable digital seismographs in the San Fernando Valley (SFV), the Los Angeles basin (LAB), and surrounding hills to record aftershocks of the 17 January 1994 Northridge California earthquake. The purpose of the deployment was to investigate factors relevant to seismic zonation in urban areas, such as site amplification, sedimentary basin effects, and the variability of ground motion over short baselines. We placed seismographs at 47 sites (not all concurrently) and recorded about 290 earthquakes with magnitudes up to 5.1 at five stations or more. We deployed widely spaced stations for profiles across the San Fernando Valley, as well as five dense arrays (apertures of 200 to 500 m) in areas of high damage, such as the collapsed Interstate 10 overpass, Sherman Oaks, and the collapsed parking garage at CalState Northridge. Aftershock data analysis indicates a correlation of site amplification with mainshock damage. We found several cases where the site amplification depended on the azimuth of the aftershock, possibly indicating focusing from basin structures. For the parking garage array, we found large ground-motion variabilities (a factor of 2) over 200-m distances for sites on the same mapped soil unit. Array analysis of the aftershock seismograms demonstrates that sizable arrivals after the direct 5 waves consist of surface waves traveling from the same azimuth as that of the epicenter. These surface waves increase the duration of motions and can have frequencies as high as about 4 Hz. For the events studied here, we do not observe large arrivals reflected from the southern edge of the San Fernando Valley.

Millimeter Wave Holographical Inspection of Honeycomb Composites

NASA Technical Reports Server (NTRS)

Case, J. T.; Kharkovsky, S.; Zoughi, R.; Stefes, G.; Hepburn, Frank L.; Hepburn, Frank L.

2007-01-01

Multi-layered composite structures manufactured with honeycomb, foam or balsa wood cores are finding increasing utility in a variety of aerospace, transportation, and infrastructure applications. Due to the low conductivity and inhomogeneity associated with these composites standard nondestructive testing (NDT) methods are not always capable of inspecting their interior for various defects caused during the manufacturing process or as a result of in-service loading. On the contrary, microwave and millimeter wave NDT methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as disbond, delamination, moisture and oil intrusion, impact damage, etc. Millimeter wave frequency spectrum spans 30 GHz - 300 GHz with corresponding wavelengths of 10 - 1 mm. Due to the inherent short wavelengths at these frequencies, one can produce high spatial resolution images of these composites either using real-antenna focused or synthetic-aperture focused methods. In addition, incorporation of swept-frequency in the latter method (i.e., holography) results in high-resolution three-dimensional images. This paper presents the basic steps behind producing such images at millimeter wave frequencies and the results of two honeycomb composite panels are demonstrated at Q-band (33-50 GHz). In addition, these results are compared to previous results using X-ray computed tomography.

Millimeter Wave Holographical Inspection of Honeycomb Composites

NASA Astrophysics Data System (ADS)

Case, J. T.; Kharkovsky, S.; Zoughi, R.; Steffes, G.; Hepburn, F. L.

2008-02-01

Multi-layered composite structures manufactured with honeycomb, foam, or balsa wood cores are finding increasing utility in a variety of aerospace, transportation, and infrastructure applications. Due to the low conductivity and inhomogeneity associated with these composites, standard nondestructive testing (NDT) methods are not always capable of inspecting their interior for various defects caused during the manufacturing process or as a result of in-service loading. On the contrary, microwave and millimeter wave NDT methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as isband, delamination, moisture and oil intrusion, impact damage, etc. Millimeter wave frequency spectrum spans 30 GHz-300 GHz with corresponding wavelengths of 10-1 mm. Due to the inherent short wavelengths at these frequencies, one can produce high spatial resolution images of these composites either using real-antenna focused or synthetic-aperture focused methods. In addition, incorporation of swept-frequency in the latter method (i.e., holography) results in high-resolution three-dimensional images. This paper presents the basic steps behind producing such images at millimeter wave frequencies and the results of two honeycomb composite panels are demonstrated at Q-band (33-50 GHz). In addition, these results are compared to previous results using X-ray computed tomography.

The Next-Generation Very Large Array: Technical Overview

NASA Astrophysics Data System (ADS)

McKinnon, Mark; Selina, Rob

2018-01-01

As part of its mandate as a national observatory, the NRAO is looking toward the long range future of radio astronomy and fostering the long term growth of the US astronomical community. NRAO has sponsored a series of science and technical community meetings to consider the science mission and design of a next-generation Very Large Array (ngVLA), building on the legacies of the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Array (VLA).The basic ngVLA design emerging from these discussions is an interferometric array with approximately ten times the sensitivity and ten times higher spatial resolution than the VLA and ALMA radio telescopes, optimized for operation in the wavelength range 0.3cm to 3cm. The ngVLA would open a new window on the Universe through ultra-sensitive imaging of thermal line and continuum emission down to milli-arcsecond resolution, as well as unprecedented broadband continuum polarimetric imaging of non-thermal processes. The specifications and concepts for major ngVLA system elements are rapidly converging.We will provide an overview of the current system design of the ngVLA. The concepts for major system elements such as the antenna, receiving electronics, and central signal processing will be presented. We will also describe the major development activities that are presently underway to advance the design.

Millimeter-wave spectroscopy of the SiCl+ ion

NASA Astrophysics Data System (ADS)

Takeda, Kazuki; Masuda, Satoshi; Harada, Kensuke; Tanaka, Keiichi

2016-05-01

The millimeter-wave spectrum of the SiCl+ ion in the ground and first excited vibrational states was observed for the two isotopic (35Cl and 37Cl) species. The ion was generated in a free-space absorption cell by a hollow cathode discharge of SiCl4 diluted with He and discriminated from neutral species by the magnetic field effect on the absorption lines. The observed millimeter-wave spectrum was combined with a previously reported diode laser spectrum in an analysis to determine mass-independent Dunham coefficients as well as the mass scaling parameters. The equilibrium bond length of SiCl+ determined is re = 1.943 978(2) Å.

Millimeter Wave Nonreciprocal Devices.

DTIC Science & Technology

1983-01-03

measures microwave magnetic field patterns of magnetostatic waves in LPE -YIG thin films has been developed. The probe’s sensing element is either a...Morgenthaler, "Workshop on Application of Garnet and Ferrite Thin Films to Microwave Devices," Session FC, Third Joint Intermag - Magnetism and...thin films Li... millimeter waves magnetostati c waves i A TRAC" =CmE4 F*91040 eEp y mnenu -d Dfenvely by Noek n.m--) The Microwave and Quantum

Imaging spectroscopy using embedded diffractive optical arrays

NASA Astrophysics Data System (ADS)

Hinnrichs, Michele; Hinnrichs, Bradford

2017-09-01

Pacific Advanced Technology (PAT) has developed an infrared hyperspectral camera based on diffractive optic arrays. This approach to hyperspectral imaging has been demonstrated in all three infrared bands SWIR, MWIR and LWIR. The hyperspectral optical system has been integrated into the cold-shield of the sensor enabling the small size and weight of this infrared hyperspectral sensor. This new and innovative approach to an infrared hyperspectral imaging spectrometer uses micro-optics that are made up of an area array of diffractive optical elements where each element is tuned to image a different spectral region on a common focal plane array. The lenslet array is embedded in the cold-shield of the sensor and actuated with a miniature piezo-electric motor. This approach enables rapid infrared spectral imaging with multiple spectral images collected and processed simultaneously each frame of the camera. This paper will present our optical mechanical design approach which results in an infrared hyper-spectral imaging system that is small enough for a payload on a small satellite, mini-UAV, commercial quadcopter or man portable. Also, an application of how this spectral imaging technology can easily be used to quantify the mass and volume flow rates of hydrocarbon gases. The diffractive optical elements used in the lenslet array are blazed gratings where each lenslet is tuned for a different spectral bandpass. The lenslets are configured in an area array placed a few millimeters above the focal plane and embedded in the cold-shield to reduce the background signal normally associated with the optics. The detector array is divided into sub-images covered by each lenslet. We have developed various systems using a different number of lenslets in the area array. Depending on the size of the focal plane and the diameter of the lenslet array will determine the number of simultaneous different spectral images collected each frame of the camera. A 2 x 2 lenslet array will image

Infrared-Bolometer Arrays with Reflective Backshorts

NASA Technical Reports Server (NTRS)

Miller, Timothy M.; Abrahams, John; Allen, Christine A.

2011-01-01

Integrated circuits that incorporate square arrays of superconducting-transition- edge bolometers with optically reflective backshorts are being developed for use in image sensors in the spectral range from far infrared to millimeter wavelengths. To maximize the optical efficiency (and, thus, sensitivity) of such a sensor at a specific wavelength, resonant optical structures are created by placing the backshorts at a quarter wavelength behind the bolometer plane. The bolometer and backshort arrays are fabricated separately, then integrated to form a single unit denoted a backshort-under-grid (BUG) bolometer array. In a subsequent fabrication step, the BUG bolometer array is connected, by use of single-sided indium bump bonding, to a readout device that comprises mostly a superconducting quantum interference device (SQUID) multiplexer circuit. The resulting sensor unit comprising the BUG bolometer array and the readout device is operated at a temperature below 1 K. The concept of increasing optical efficiency by use of backshorts at a quarter wavelength behind the bolometers is not new. Instead, the novelty of the present development lies mainly in several features of the design of the BUG bolometer array and the fabrication sequence used to implement the design. Prior to joining with the backshort array, the bolometer array comprises, more specifically, a square grid of free-standing molybdenum/gold superconducting-transition-edge bolometer elements on a 1.4- m-thick top layer of silicon that is part of a silicon support frame made from a silicon-on-insulator wafer. The backshort array is fabricated separately as a frame structure that includes support beams and contains a correspond - ing grid of optically reflective patches on a single-crystal silicon substrate. The process used to fabricate the bolometer array includes standard patterning and etching steps that result in the formation of deep notches in the silicon support frame. These notches are designed to

Untuned resonators for near millimeter waves

NASA Astrophysics Data System (ADS)

Gebbie, H. A.; Llewellyn-Jones, D. T.

1981-03-01

A brief account is given of the reasons for revitalizing an old technique for near millimeter wave measurements. The principles of the method are outlined and the scope of its application indicated. The potential importance of the technique for liquid phase and biological material studies is illustrated.

Integrated Electron-tunneling Refrigerator and TES Bolometer for Millimeter Wave Astronomy

NASA Technical Reports Server (NTRS)

Silverberg, R. F.; Benford, D. J.; Chen, T. C.; Chervenak, J.; Finkbeiner, F.; Moseley, S. H.; Duncan, W.; Miller, N.; Schmidt, D.; Ullom, J.

2005-01-01

We describe progress in the development of a close-packed array of bolometers intended for use in photometric applications at millimeter wavelengths from ground- based telescopes. Each bolometer in the may uses a proximity-effect Transition Edge Sensor (TES) sensing element and each will have integrated Normal-Insulator-Superconductor (NIS) refrigerators to cool the bolometer below the ambient bath temperature. The NIS refrigerators and acoustic-phonon-mode-isolated bolometers are fabricated on silicon. The radiation-absorbing element is mechanically suspended by four legs, whose dimensions are used to control and optimize the thermal conductance of the bolometer. Using the technology developed at NIST, we fabricate NIS refrigerators at the base of each of the suspension legs. The NIS refrigerators remove hot electrons by quantum-mechanical tunneling and are expected to cool the biased (approx.10 pW) bolometers to <170 mK while the bolometers are inside a pumped 3He-cooled cryostat operating at approx.280 mK. This significantly lower temperature at the bolometer allows the detectors to approach background-limited performance despite the simple cryogenic system.

[Acoustic detection of absorption of millimeter-band electromagnetic waves in biological objects].

PubMed

Polnikov, I G; Putvinskiĭ, A V

1988-01-01

Principles of photoacoustic spectroscopy were applied to elaborate a new method for controlling millimeter electromagnetic waves absorption in biological objects. The method was used in investigations of frequency dependence of millimeter wave power absorption in vitro and in vivo in the commonly used experimental irradiation systems.

Millimeter radiometer system technology

NASA Technical Reports Server (NTRS)

Wilson, W. J.; Swanson, P. N.

1989-01-01

JPL has had a large amount of experience with spaceborne microwave/millimeter wave radiometers for remote sensing. All of the instruments use filled aperture antenna systems from 5 cm diameter for the microwave Sounder Units (MSU), 16 m for the microwave limb sounder (MLS) to 20 m for the large deployable reflector (LDR). The advantages of filled aperture antenna systems are presented. The requirements of the 10 m Geoplat antenna system, 10 m multified antenna, and the MLS are briefly discussed.

Millimeter radiometer system technology

NASA Astrophysics Data System (ADS)

Wilson, W. J.; Swanson, P. N.

1989-07-01

JPL has had a large amount of experience with spaceborne microwave/millimeter wave radiometers for remote sensing. All of the instruments use filled aperture antenna systems from 5 cm diameter for the microwave Sounder Units (MSU), 16 m for the microwave limb sounder (MLS) to 20 m for the large deployable reflector (LDR). The advantages of filled aperture antenna systems are presented. The requirements of the 10 m Geoplat antenna system, 10 m multified antenna, and the MLS are briefly discussed.

Sparse interferometric millimeter-wave array for centimeter-level 100-m standoff imaging

NASA Astrophysics Data System (ADS)

Suen, Jonathan Y.; Lubin, Philip M.; Solomon, Steven L.; Ginn, Robert P.

2013-05-01

We present work on the development of a long range standoff concealed weapons detection system capable of imaging under very heavy clothing at distances exceeding 100 m with a cm resolution. The system is based off a combination of phased array technologies used in radio astronomy and SAR radar by using a coherent, multi-frequency reconstruction algorithm which can run at up to 1000 Hz frame rates and high SNR with a multi-tone transceiver. We show the flexible design space of our system as well as algorithm development, predicted system performance and impairments, and simulated reconstructed images. The system can be used for a variety of purposes including portal applications, crowd scanning and tactical situations. Additional uses include seeing through dust and fog.

Multi Ray Model for Near-Ground Millimeter Wave Radar

PubMed Central

Litvak, Boris; Pinhasi, Yosef

2017-01-01

A quasi-optical multi-ray model for a short-range millimeter wave radar is presented. The model considers multi-path effects emerging while multiple rays are scattered from the target and reflected to the radar receiver. Among the examined scenarios, the special case of grazing ground reflections is analyzed. Such a case becomes relevant when short range anti-collision radars are employed in vehicles. Such radars operate at millimeter wavelengths, and are aimed at the detection of targets located several tens of meters from the transmitter. Reflections from the road are expected to play a role in the received signal strength, together with the direct line-of-sight beams illuminated and scattered from the target. The model is demonstrated experimentally using radar operating in the W-band. Controlled measurements were done to distinguish between several scattering target features. The experimental setup was designed to imitate vehicle near-ground millimeter wave radars operating in vehicles. A comparison between analytical calculations and experimental results is made and discussed. PMID:28867776

Millimeter Wave Radar Clutter Program

DTIC Science & Technology

1989-10-30

conduct experimental measurments and develop theoretical models to Improve our understanding of electromagnetic wave interaction with terrain at...various types of terrain under a variety of conditions. The experimental data servos to guide the development of the models as well as to verify their... experimental measurement. Task 4 - Examination of Bistatic Scattering from Surfaces and Volumes: Prior to this program, no millimeter-wave bistatic

Nanotube Surface Arrays: Weaving, Bending, and Assembling on Patterned Silicon

NASA Astrophysics Data System (ADS)

Tsukruk, Vladimir V.; Ko, Hyunhyub; Peleshanko, Sergiy

2004-02-01

We report the fabrication of ordered arrays of oriented and bent carbon nanotube on a patterned silicon surface with a micron scale spacing extending over millimeter size surface areas. We suggest that the patterning is controlled by the hydrodynamic behavior of a fluid front and orientation and bending mechanisms are facilitated by the pinned carbon nanotubes trapped by the liquid-solid-vapor contact line. The bending of the pinned nanotubes occurs along the shrinking receding front of the drying microdroplets. The formation of stratified microfluidic layers is vital for stimulating periodic instabilities of the contact line.

RF to millimeter wave integration and module technologies

NASA Astrophysics Data System (ADS)

Vähä-Heikkilä, T.

2015-04-01

Radio Frequency (RF) consumer applications have boosted silicon integrated circuits (IC) and corresponding technologies. More and more functions are integrated to ICs and their performance is also increasing. However, RF front-end modules with filters and switches as well as antennas still need other way of integration. This paper focuses to RF front-end module and antenna developments as well as to the integration of millimeter wave radios. VTT Technical Research Centre of Finland has developed both Low Temperature Co-fired Ceramics (LTCC) and Integrated Passive Devices (IPD) integration platforms for RF and millimeter wave integrated modules. In addition to in-house technologies, VTT is using module and component technologies from other commercial sources.

Measurements of millimeter wave radar transmission and backscatter during dusty infrared test 2, dirt 2

NASA Astrophysics Data System (ADS)

Petito, F. C.; Wentworth, E. W.

1980-05-01

Recently there has been much interest expressed to determine the ability of millimeter wave radar to perform target acquisition during degraded visibility conditions. In this regard, one of the primary issues of concern has been the potential of high-explosive artillery barrages to obscure the battlefield from millimeter wave radar systems. To address this issue 95 GHz millimeter wave radar measurements were conducted during the Dusty Infrared Test 2 (DIRT 2). This test was held at White Sands Missile Range, NM, 18-28 July 1979. Millimeter wave transmission and backscatter measurements were performed during singular live firings and static detonations of 155 mm and 105 mm high-explosive artillery rounds in addition to static detonations of C-4 explosives. A brief description of the millimeter wave portion of the test and instrumentation is given. The data along with some preliminary conclusions are presented.

Performance modeling of terahertz (THz) and millimeter waves (mmW) pupil plane imaging

NASA Astrophysics Data System (ADS)

Mohammadian, Nafiseh; Furxhi, Orges; Zhang, Lei; Offermans, Peter; Ghazi, Galia; Driggers, Ronald

2018-05-01

Terahertz- (THz) and millimeter-wave sensors are becoming more important in industrial, security, medical, and defense applications. A major problem in these sensing areas is the resolution, sensitivity, and visual acuity of the imaging systems. There are different fundamental parameters in designing a system that have significant effects on the imaging performance. The performance of THz systems can be discussed in terms of two characteristics: sensitivity and spatial resolution. New approaches for design and manufacturing of THz imagers are a vital basis for developing future applications. Photonics solutions have been at the technological forefront in THz band applications. A single scan antenna does not provide reasonable resolution, sensitivity, and speed. An effective approach to imaging is placing a high-performance antenna in a two-dimensional antenna array to achieve higher radiation efficiency and higher resolution in the imaging systems. Here, we present the performance modeling of a pupil plane imaging system to find the resolution and sensitivity efficiency of the imaging system.

Far-Infrared and Millimeter Continuum Studies of K-Giants: Alpha Boo and Alpha Tau

NASA Technical Reports Server (NTRS)

Cohen, Martin; Carbon, Duane F.; Welch, William J.; Lim, Tanya; Forster, James R.; Goorvitch, David; Thigpen, William (Technical Monitor)

2002-01-01

We have imaged two normal, non-coronal, infrared-bright K-giants, alpha Boo and alpha Tau, in the 1.4-millimeter and 2.8-millimeter continuum using BIMA. These stars have been used as important absolute calibrators for several infrared satellites. Our goals are: (1) to probe the structure of their upper photospheres; (2) to establish whether these stars radiate as simple photospheres or possess long-wavelength chromospheres; and (3) to make a connection between millimeter-wave and far-infrared absolute flux calibrations. To accomplish these goals we also present ISO Long Wavelength Spectrometer (LWS) measurements of both these K-giants. The far-infrared and millimeter continuum radiation is produced in the vicinity of the temperature minimum in a Boo and a Tau, offering a direct test of the model photospheres and chromospheres for these two cool giants. We find that current photospheric models predict fluxes in reasonable agreement with those observed for those wavelengths which sample the upper photosphere, namely less than or equal to 170 micrometers in alpha Tau and less than or equal to 125 micrometers in alpha Boo. It is possible that alpha Tau is still radiative as far as 0.9 - 1.4 millimeters. We detect chromospheric radiation from both stars by 2.8 millimeters (by 1.4 millimeters in alpha Boo), and are able to establish useful bounds on the location of the temperature minimum. An attempt to interpret the chromospheric fluxes using the two-component "bifurcation model" proposed by Wiedemann et al. (1994) appears to lead to a significant contradiction.

Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics

NASA Astrophysics Data System (ADS)

Nagayama, Y.; Ito, N.; Kuwahara, D.; Tsuchiya, H.; Yamaguchi, S.

2017-04-01

The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 1019 m-3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

Millimeter-wave studies

NASA Technical Reports Server (NTRS)

Allen, Kenneth C.

1988-01-01

Progress on millimeter-wave propagation experiments in Hawaii is reported. A short path for measuring attenuation in rain at 9.6, 28.8, 57.6, and 96.1 GHz is in operation. A slant path from Hilo to the top of Mauna Kea is scheduled. On this path, scattering from rain and clouds that may cause interference for satellites closely spaced in geosynchronous orbit will be measured at the same frequencies at 28.8 and 96.1 GHz. In addition the full transmission matrix will be measured at the same frequencies on the slant path. The technique and equipment used to measure the transmission matrix are described.

Identifying explosives using broadband millimeter-wave imaging

NASA Astrophysics Data System (ADS)

Weatherall, James C.; Yam, Kevin; Barber, Jeffrey; Smith, Barry T.; Smith, Peter R.; Greca, Joseph

2017-05-01

Millimeter wave imaging is employed in Advanced Technology Imaging (AIT) systems to screen personnel for concealed explosives and weapons. AIT systems deployed in airports auto-detect potential threats by highlighting their location on a generic outline of a person using imaging data collected over a range of frequency. We show how the spectral information from the imaging data can be used to identify the composition of an anomalous object, in particular if it is an explosive material. The discriminative value of the technique was illustrated on military sheet explosive using millimeter-wave reflection data at frequencies 18 - 40 GHz, and commercial explosives using 2 - 18 GHz, but the free-space measurement was limited to a single horn with a large-area sample. This work extends the method to imaging data collected at high resolution with a 18 - 40 GHz imaging system. The identification of explosives is accomplished by extracting the dielectric constant from the free-space, multifrequency data. The reflection coefficient is a function of frequency because of propagation effects associated with the material's complex dielectric constant, which include interference from multiple reflections and energy loss in the sample. The dielectric constant is obtained by numerically fitting the reflection coefficient as a function of frequency to an optical model. In principal, the implementation of this technique in standoff imaging systems would allow threat assessment to be accomplished within the scope of millimeter-wave screening.

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mears, Carl Atherton

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit bymore » studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 ± 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker`s theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.« less

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mears, C.A.

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit bymore » studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 {plus minus} 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.« less

Understanding the variation in the millimeter-wave emission of Venus

NASA Technical Reports Server (NTRS)

Fahd, Antoine K.; Steffes, Paul G.

1992-01-01

Recent observations of the millimeter-wave emission from Venus at 112 GHz (2.6 mm) have shown significant variations in the continuum flux emission that may be attributed to the variability in the abundances of absorbing constituents in the Venus atmosphere. Such constituents include gaseous H2SO4, SO2, and liquid sulfuric acid (cloud condensates). Recently, Fahd and Steffes have shown that the effects of liquid H, SO4, and gaseous SO2 cannot completely account for this measured variability in the millimeter-wave emission of Venus. Thus, it is necessary to study the effect of gaseous H2SO4 on the millimeter-wave emission of Venus. This requires knowledge of the millimeter-wavelength (MMW) opacity of gaseous H2SO4, which unfortunately has never been determined for Venus-like conditions. We have measured the opacity of gaseous H2SO4 in a CO2 atmosphere at 550, 570, and 590 K, at 1 and 2 atm total pressure, and at a frequency of 94.1 GHz. Our results, in addition to previous centimeter-wavelength results are used to verify a modeling formalism for calculating the expected opacity of this gaseous mixture at other frequencies. This formalism is incorporated into a radiative transfer model to study the effect of gaseous H2SO4 on the MMW emission of Venus.

Study and interpretation of the millimeter-wave spectrum of Venus

NASA Technical Reports Server (NTRS)

Fahd, Antoine K.; Steffes, Paul G.

1992-01-01

The effects of the Venus atmospheric constituents on its millimeter wavelength emission are investigated. Specifically, this research describes the methodology and the results of laboratory measurements which are used to calculate the opacity of some of the major absorbers in the Venus atmosphere. The pressure broadened absorption of gaseous SO2/CO2 and gaseous H2SO4/CO2 has been measured at millimeter wavelengths. We have also developed new formalisms for computing the absorptivities of these gases based on our laboratory work. The complex dielectric constant of liquid sulfuric acid has been measured and the expected opacity from the liquid sulfuric acid cloud layer found in the atmosphere of Venus has been evaluated. The partial pressure of gaseous H2SO4 has been measured which results in a more accurate estimate of the dissociation factor of H2SO4. A radiative transfer model has been developed in order to understand how each atmospheric constituent affects the millimeter wave emissions from Venus. Our results from the radiative transfer model are compared with recent observations of the micro-wave and millimeter wave emissions from Venus. Our main conclusion from this work is that gaseous H2SO4 is the most likely cause of the variation in the observed emission from Venus at 112 GHz.

Millimeter-wave generation with spiraling electron beams

NASA Technical Reports Server (NTRS)

Kulke, B.

1971-01-01

The feasibility of using the interaction between a thin, solid, spiraling electron beam of 10 to 20 kV energy and a microwave cavity to generate watts of CW millimeter-wave power was investigated. Experimental results are given for several prototype devices operating at 9.4 GHz and at 94 GHz. Power outputs of 5 W, and electronic efficiencies near 3%, were obtained at X band, and moderate gain was obtained at 94 GHz. The small-signal theory gives a good fit to the X-band data, and the device behavior at 94 GHz is as expected from the given beam characteristics. The performance is limited chiefly by the velocity spread in the spiraling electron beam, and once this can be brought under control, high-power generation of millimeter waves appears quite feasible with this type of device.

Passive millimeter-wave imaging

NASA Technical Reports Server (NTRS)

Young, Stephen K.; Davidheiser, Roger A.; Hauss, Bruce; Lee, Paul S. C.; Mussetto, Michael; Shoucri, Merit M.; Yujiri, Larry

1993-01-01

Millimeter-wave hardware systems are being developed. Our approach begins with identifying and defining the applications. System requirements are then specified based on mission needs using our end-to-end performance model. The model was benchmarked against existing data bases and, where data is deficient, it is acquired via field measurements. The derived system requirements are then validated with the appropriate field measurements using our imaging testbeds and hardware breadboards. The result is a final system that satisfies all the requirements of the target mission.

77 FR 33237 - Saline Valley Warm Springs Management Plan/Environmental Impact Statement, Death Valley National...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-05

... Valley Warm Springs Management Plan/Environmental Impact Statement, Death Valley National Park, Inyo... an Environmental Impact Statement for the Saline Valley Warm Springs Management Plan, Death Valley... analysis process for the Saline Valley Warm Springs Management Plan for Death Valley [[Page 33238...

Low-cost three-dimensional millimeter-wave holographic imaging system based on a frequency-scanning antenna.

PubMed

Amin Nili, Vahid; Mansouri, Ehsan; Kavehvash, Zahra; Fakharzadeh, Mohammad; Shabany, Mahdi; Khavasi, Amin

2018-01-01

In this paper, a closed-form two-dimensional reconstruction technique for hybrid frequency and mechanical scanning millimeter-wave (MMW) imaging systems is proposed. Although being commercially implemented in many imaging systems as a low-cost real-time solution, the results of frequency scanning systems have been reconstructed numerically or have been reported as the captured raw data with no clear details. Furthermore, this paper proposes a new framework to utilize the captured data of different frequencies for three-dimensional (3D) reconstruction based on novel proposed closed-form relations. The hybrid frequency and mechanical scanning structure, together with the proposed reconstruction method, yields a low-cost MMW imaging system with a satisfying performance. The extracted reconstruction formulations are validated through numerical simulations, which show comparable image quality with conventional MMW imaging systems, i.e., switched-array (SA) and phased-array (PA) structures. Extensive simulations are also performed in the presence of additive noise, demonstrating the acceptable robustness of the system against system noise compared to SA and comparable performance with PA. Finally, 3D reconstruction of the simulated data shows a depth resolution of better than 10 cm with minimum degradation of lateral resolution in the 10 GHz frequency bandwidth.

Photon Transport in One-Dimensional Incommensurately Epitaxial CsPbX 3 Arrays

DOE PAGES

Wang, Yiping; Sun, Xin; Shivanna, Ravichandran; ...

2016-11-16

One-dimensional nanoscale epitaxial arrays serve as a great model in studying fundamental physics and for emerging applications. With an increasing focus laid on the Cs-based inorganic halide perovskite out of its outstanding material stability, we have applied vapor phase epitaxy to grow well aligned horizontal CsPbX 3 (X: Cl, Br, or I or their mixed) nanowire arrays in large scale on mica substrate. The as-grown nanowire features a triangular prism morphology with typical length ranging from a few tens of micrometers to a few millimeters. Structural analysis reveals that the wire arrays follow the symmetry of mica substrate through incommensuratemore » epitaxy, paving a way for a universally applicable method to grow a broad family of halide perovskite materials. We have studied the unique photon transport in the one-dimensional structure in the all-inorganic Cs-based perovskite wires via temperature dependent and spatially resolved photoluminescence. Furthermore, epitaxy of well oriented wire arrays in halide perovskite would be a promising direction for enabling the circuit-level applications of halide perovskite in high-performance electro-optics and optoelectronics.« less

[Impact of various millimeter-range electromagnetic radiation schedules on immunological parameters in patients with respiratory sarcoidosis].

PubMed

Borisov, S B; Shpykov, A S; Terent'eva, N A

2007-01-01

The paper analyzes the impact of various millimeter-range electromagnetic radiation schedules on immunological parameters in 152 patients with new-onset respiratory sarcoidosis. It shows that the immunomodulatory effect of millimeter-range therapy depends on the treatment regimen chosen. There is evidence for the advantages of millimeter-range noise electromagnetic radiation.

Millimeter-Wave Generation with Spiraling Electron Beams

DOT National Transportation Integrated Search

1971-02-01

An investigation has been carried out of the feasibility : of using the interaction between a thin, solid, : spiraling electron beam of 10-20kV energy and a microwave : cavity to generate watts of CW millimeter-wave power. : Experimental results are ...

Continuous millimeter-wave radiation has no effect on lipid peroxidation in liposomes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Logani, M.K.; Ziskin, M.C.

1996-02-01

The effect of millimeter waves on lipid peroxidation was studied in the presence and absence of melanin. Irradiation of liposomes with continuous millimeter electromagnetic waves at frequencies of 53.6, 61.2 and 78.2 GHz and incident power densities of 10, 1 and 500 mW/cm{sup 2}, respectively, did not show an enhancement in the formation of lipid peroxides compared to unirradiated samples. Liposomes exposed to 254 nm UVC radiation at 0.32 mW/cm{sup 2} and 302 nm UVB radiation at 1.12 mW/cm{sup 2} served as positive controls. No increment in the formation of lipid peroxides was observed when irradiation of liposomes was carriedmore » out in the presence of ADP-Fe{sup +3} and EDTA-Fe{sup +3}. Direct irradiation of melanin with millimeter waves did not exhibit an increased formation of superoxide or hydrogen peroxide. The present results indicate that millimeter waves of the above frequencies and intensities do not cause lipid peroxidation in liposomal membranes. 19 refs., 2 figs., 1 tab.« less

27 CFR 9.57 - Green Valley of Russian River Valley.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Green Valley of Russian River Valley. 9.57 Section 9.57 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.57 Green Valley of Russian River...

27 CFR 9.57 - Green Valley of Russian River Valley.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Green Valley of Russian River Valley. 9.57 Section 9.57 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.57 Green Valley of Russian River...

27 CFR 9.57 - Green Valley of Russian River Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Green Valley of Russian River Valley. 9.57 Section 9.57 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.57 Green Valley of Russian River...

27 CFR 9.57 - Green Valley of Russian River Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Green Valley of Russian River Valley. 9.57 Section 9.57 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.57 Green Valley of Russian River...

27 CFR 9.57 - Green Valley of Russian River Valley.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Green Valley of Russian River Valley. 9.57 Section 9.57 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.57 Green Valley of Russian River...

Site characterization at the Rabbit Valley Geophysical Performance Evaluation Range

NASA Astrophysics Data System (ADS)

Koppenjan, S.,; Martinez, M.

The United States Department of Energy (US DOE) is developing a Geophysical Performance Evaluation Range (GPER) at Rabbit Valley located 30 miles west of Grand Junction, Colorado. The purpose of the range is to provide a test area for geophysical instruments and survey procedures. Assessment of equipment accuracy and resolution is accomplished through the use of static and dynamic physical models. These models include targets with fixed configurations and targets that can be re-configured to simulate specific specifications. Initial testing (1991) combined with the current tests at the Rabbit Valley GPER will establish baseline data and will provide performance criteria for the development of geophysical technologies and techniques. The US DOE's Special Technologies Laboratory (STL) staff has conducted a Ground Penetrating Radar (GPR) survey of the site with its stepped FM-CW GPR. Additionally, STL contracted several other geophysical tests. These include an airborne GPR survey incorporating a 'chirped' FM-CW GPR system and a magnetic survey with a surfaced-towed magnetometer array unit Ground-based and aerial video and still frame pictures were also acquired. STL compiled and analyzed all of the geophysical maps and created a site characterization database. This paper discusses the results of the multi-sensor geophysical studies performed at Rabbit Valley and the future plans for the site.

First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.

PubMed

Maruta, Kazuki; Iwakuni, Tatsuhiko; Ohta, Atsushi; Arai, Takuto; Shirato, Yushi; Kurosaki, Satoshi; Iizuka, Masataka

2016-07-08

Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity.

Channel microband electrode arrays for mechanistic electrochemistry. Two-dimensional voltammetry:  transport-limited currents.

PubMed

Alden, J A; Feldman, M A; Hill, E; Prieto, F; Oyama, M; Coles, B A; Compton, R G; Dobson, P J; Leigh, P A

1998-05-01

A channel electrode array, with electrodes ranging in size from the millimeter to the submicrometer scale, is used for the amperometric interrogation of mechanistically complex electrode processes. In this way, the transport-limited current, measured as a function of both electrode size and electrolyte flow rate (convection), is shown to provide a highly sensitive probe of mechanism and kinetics. The application of "two-dimensional voltammetry" to diverse electrode processes, including E, ECE, ECEE, EC', and DISP2 reactions, is reported.

Bolometric Array Detectors for Space-Borne Astronomy

NASA Technical Reports Server (NTRS)

Lange, Andrew E.

2000-01-01

Funding from the NASA Innovative Research Grant was used to develop bolometric detectors. As described in the proposal, silicon nitride micromesh ('spider-web') absorbers had been demonstrated at U.C. Berkeley but not developed to be flight-worthy devices. We proceeded to first fabricate bolometers with Neutron Transmutation Doped (NTD) Ge thermistors that demonstrated high optical coupling (Church et al. 1996) and were developed for a ground-based millimeter-wave receiver (Mauskopf et al. 1997). The next generation of devices used In bump-bonded thermistors to achieve devices with performance product NEP*sqrt(tau) = 3e - 18 j at 300 mK, demonstrating a full order of magnitude improvement over pervious devices. These devices achieved an NEP = 1e-18 W/rtHz (Murray et al. 1996) as promised in the proposal. Sensitivities as good as 1e - 19 W/rtHz appear achievable with the silicon nitride architecture (Bock et al. 1997). Finally, arrays of micromesh bolometers were shown to be feasible in the last year of the program by etching a large number of devices on a single silicon wafer (75 mm). Full arrays were subsequently demonstrated for selection on the ESA/NASA Far-Infrared Space Telescope (FIRST) in competition with detectors provided by CEA in France and GSFC in the US Micromesh bolometer arrays are now baselined for both the ESA/NASA Planck and FIRST missions.

Novel Techniques for Millimeter-Wave Packages

NASA Technical Reports Server (NTRS)

Herman, Martin I.; Lee, Karen A.; Kolawa, Elzbieta A.; Lowry, Lynn E.; Tulintseff, Ann N.

1995-01-01

A new millimeter-wave package architecture with supporting electrical, mechanical and material science experiment and analysis is presented. This package is well suited for discrete devices, monolithic microwave integrated circuits (MMIC's) and multichip module (MCM) applications. It has low-loss wide-band RF transitions which are necessary to overcome manufacturing tolerances leading to lower per unit cost Potential applications of this new packaging architecture which go beyond the standard requirements of device protection include integration of antennas, compatibility to photonic networks and direct transitions to waveguide systems. Techniques for electromagnetic analysis, thermal control and hermetic sealing were explored. Three dimensional electromagnetic analysis was performed using a finite difference time-domain (FDTD) algorithm and experimentally verified for millimeter-wave package input and output transitions. New multi-material system concepts (AlN, Cu, and diamond thin films) which allow excellent surface finishes to be achieved with enhanced thermal management have been investigated. A new approach utilizing block copolymer coatings was employed to hermetically seal packages which met MIL STD-883.

An Off-Grid Turbo Channel Estimation Algorithm for Millimeter Wave Communications.

PubMed

Han, Lingyi; Peng, Yuexing; Wang, Peng; Li, Yonghui

2016-09-22

The bandwidth shortage has motivated the exploration of the millimeter wave (mmWave) frequency spectrum for future communication networks. To compensate for the severe propagation attenuation in the mmWave band, massive antenna arrays can be adopted at both the transmitter and receiver to provide large array gains via directional beamforming. To achieve such array gains, channel estimation (CE) with high resolution and low latency is of great importance for mmWave communications. However, classic super-resolution subspace CE methods such as multiple signal classification (MUSIC) and estimation of signal parameters via rotation invariant technique (ESPRIT) cannot be applied here due to RF chain constraints. In this paper, an enhanced CE algorithm is developed for the off-grid problem when quantizing the angles of mmWave channel in the spatial domain where off-grid problem refers to the scenario that angles do not lie on the quantization grids with high probability, and it results in power leakage and severe reduction of the CE performance. A new model is first proposed to formulate the off-grid problem. The new model divides the continuously-distributed angle into a quantized discrete grid part, referred to as the integral grid angle, and an offset part, termed fractional off-grid angle. Accordingly, an iterative off-grid turbo CE (IOTCE) algorithm is proposed to renew and upgrade the CE between the integral grid part and the fractional off-grid part under the Turbo principle. By fully exploiting the sparse structure of mmWave channels, the integral grid part is estimated by a soft-decoding based compressed sensing (CS) method called improved turbo compressed channel sensing (ITCCS). It iteratively updates the soft information between the linear minimum mean square error (LMMSE) estimator and the sparsity combiner. Monte Carlo simulations are presented to evaluate the performance of the proposed method, and the results show that it enhances the angle detection

Synthesis of millimeter-scale transition metal dichalcogenides single crystals

DOE PAGES

Gong, Yongji; Ye, Gonglan; Lei, Sidong; ...

2016-02-10

The emergence of semiconducting transition metal dichalcogenide (TMD) atomic layers has opened up unprecedented opportunities in atomically thin electronics. Yet the scalable growth of TMD layers with large grain sizes and uniformity has remained very challenging. Here is reported a simple, scalable chemical vapor deposition approach for the growth of MoSe2 layers is reported, in which the nucleation density can be reduced from 105 to 25 nuclei cm -2, leading to millimeter-scale MoSe 2 single crystals as well as continuous macrocrystalline films with millimeter size grains. The selective growth of monolayers and multilayered MoSe2 films with well-defined stacking orientation canmore » also be controlled via tuning the growth temperature. In addition, periodic defects, such as nanoscale triangular holes, can be engineered into these layers by controlling the growth conditions. The low density of grain boundaries in the films results in high average mobilities, around ≈42 cm 2 V -1 s -1, for back-gated MoSe 2 transistors. This generic synthesis approach is also demonstrated for other TMD layers such as millimeter-scale WSe 2 single crystals.« less

Design and Fabrication Highlights Enabling a 2 mm, 128 Element Bolometer Array for GISMO

NASA Technical Reports Server (NTRS)

Allen, Christine; Benford, Dominic; Miller, Timothy; Staguhn, Johannes; Wollack, Edward; Moseley, Harvey

2007-01-01

The Backshort-Under-Grid (BUG) superconducting bolometer array architecture is intended to be highly versatile, operating in a large range of wavelengths and background conditions. We have undertaken a three-year program to develop key technologies and processes required to build kilopixel arrays. To validate the basic array design and to demonstrate its applicability for future kilopixel arrays, we have chosen to demonstrate a 128 element bolometer array optimized for 2 mm wavelength using a newly built Goddard instrument, GISMO (Goddard /RAM Superconducting 2-millimeter Observer). The arrays are fabricated using batch wafer processing developed and optimized for high pixel yield, low noise, and high uniformity. The molybdenum-gold superconducting transition edge sensors are fabricated using batch sputter deposition and are patterned using dry etch techniques developed at Goddard. With a detector pitch of 2 mm 8x16 array for GISMO occupies nearly one half of the processing area of a 100 mm silicon-on-insulator starting wafer. Two such arrays are produced from a single wafer along with witness samples for process characterization. To provide thermal isolation for the detector elements, at the end of the process over 90% of the silicon must be removed using deep reactive ion etching techniques. The electrical connections for each bolometer element are patterned on the top edge of the square grid supporting the array. The design considerations unique to GISMO, key fabrication challenges, and laboratory experimental results will be presented.

Morphology of large valleys on Hawaii - Evidence for groundwater sapping and comparisons with Martian valleys

NASA Technical Reports Server (NTRS)

Kochel, R. Craig; Piper, Jonathan F.

1986-01-01

Morphometric data on the runoff and sapping valleys on the slopes of Hawaii and Molokai in Hawaii are analyzed. The analysis reveals a clear distinction between the runoff valleys and sapping valleys. The Hawaiian sapping valleys are characterized by: (1) steep valley walls and flat floors, (2) amphitheater heads, (3) low drainage density, (4) paucity of downstream tributaries, (5) low frequency of up-dip tributaries, and (6) structural and stratigraphic control on valley patterns. The characteristics of the Hawaiian sapping valleys are compared to Martian valleys and experimental systems, and good correlation between the data is detected. Flume experiments were also conducted to study the evolution of sapping valleys in response to variable structure and stratigraphy.

Linearly Tapered Slot Antenna Radiation Characteristics at Millimeter-Wave Frequencies

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Lee, Richard Q.

1998-01-01

An endfire travelling wave antenna, such as, a linearly tapered slot antenna (LTSA) is a viable alternative to a patch antenna at millimeter-wave frequencies because of its simple design and ease of fabrication. This paper presents the radiation characteristics of LTSA at higher millimeter-wave frequencies. The measured radiation patterns are observed to be well behaved and symmetric with the main beam in the endfire direction. The measured gain is about 10 dB. The LTSAs have potential wireless applications at 50 GHz, 77 GHz, and 94 GHz.

Fabrication and characterization of ordered arrays of nanostructures

NASA Astrophysics Data System (ADS)

Larson, Preston

2005-11-01

Nanostructures are currently of great interest because of their unique properties and potential applications in a wide range of areas such as opto-electronic and biomedical devices. Current research in nanotechnology involves fabrication and characterization of these structures, as well as theoretical and experimental studies to explore their unique and novel properties. Not only do nanostructures have the potential to be both evolutionary (state-of-the-art ICs have more and more features on the nanoscale) but revolutionary (quantum computing) as well. In this thesis, a combination of bottom-up and top-down approaches is explored to fabricate ordered arrays of nanostrucutures. The bottom-up approach involves the growth of self-organized porous anodic aluminum oxide (AAO) films. AAO films consist of a well ordered hexagonal array of close-packed pores with diameters and spacings ranging from around 5 to 500 nm. Via a top-down approach, these AAO films are then used as masks or templates to fabricate ordered arrays of nanostructures (i.e. dots, holes, meshes, pillars, rings, etc.) of various materials using conventional deposition and/or etching techniques. Using AAO films as masks allows a simple and economical method to fabricate arrays of structures with nano-scale dimensions. Furthermore, they allow the fabrication of large areas (many millimeters on a side) of highly uniform and well-ordered arrays of nanostructures, a crucial requirement for most characterization techniques and applications. Characterization of these nanostructures using various techniques (electron microscopy, atomic force microscopy, UV-Vis absorption spectroscopy, photoluminescence, capacitance-voltage measurements, magnetization hysteresis curves, etc.) will be presented. Finally, these structures provide a unique opportunity to determine the single and collective properties of nanostructure arrays and will have various future applications including but not limited to: data storage, light

Ground-water flow directions and estimation of aquifer hydraulic properties in the lower Great Miami River Buried Valley aquifer system, Hamilton Area, Ohio

USGS Publications Warehouse

Sheets, Rodney A.; Bossenbroek, Karen E.

2005-01-01

The Great Miami River Buried Valley Aquifer System is one of the most productive sources of potable water in the Midwest, yielding as much as 3,000 gallons per minute to wells. Many water-supply wells tapping this aquifer system are purposely placed near rivers to take advantage of induced infiltration from the rivers. The City of Hamilton's North Well Field consists of 10 wells near the Great Miami River, all completed in the lower Great Miami River Buried Valley Aquifer System. A well-drilling program and a multiple-well aquifer test were done to investigate ground-water flow directions and to estimate aquifer hydraulic properties in the lower part of the Great Miami River Buried Valley Aquifer System. Descriptions of lithology from 10 well borings indicate varying amounts and thickness of clay or till, and therefore, varying levels of potential aquifer confinement. Borings also indicate that the aquifer properties can change dramatically over relatively short distances. Grain-size analyses indicate an average bulk hydraulic conductivity value of aquifer materials of 240 feet per day; the geometric mean of hydraulic conductivity values of aquifer material was 89 feet per day. Median grain sizes of aquifer material and clay units were 1.3 millimeters and 0.1 millimeters, respectively. Water levels in the Hamilton North Well Field are affected by stream stage in the Great Miami River and barometric pressure. Bank storage in response to stream stage is evident. Results from a multiple-well aquifer test at the well field indicate, as do the lithologic descriptions, that the aquifer is semiconfined in some areas and unconfined in others. Transmissivity and storage coefficient of the semiconfined part of the aquifer were 50,000 feet squared per day and 5x10-4, respectively. The average hydraulic conductivity (450 feet per day) based on the aquifer test is reasonable for glacial outwash but is higher than calculated from grain-size analyses, implying a scale effect

Contactless measurement of electrical conductivity of semiconductor wafers using the reflection of millimeter waves

NASA Astrophysics Data System (ADS)

Ju, Yang; Inoue, Kojiro; Saka, Masumi; Abe, Hiroyuki

2002-11-01

We present a method for quantitative measurement of electrical conductivity of semiconductor wafers in a contactless fashion by using millimeter waves. A focusing sensor was developed to focus a 110 GHz millimeter wave beam on the surface of a silicon wafer. The amplitude and the phase of the reflection coefficient of the millimeter wave signal were measured by which electrical conductivity of the wafer was determined quantitatively, independent of the permittivity and thickness of the wafers. The conductivity obtained by this method agrees well with that measured by the conventional four-point-probe method.

Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics.

PubMed

Nagayama, Y; Ito, N; Kuwahara, D; Tsuchiya, H; Yamaguchi, S

2017-04-01

The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 10 19 m -3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

On the mechanisms of interaction of low-intensity millimeter waves with biological objects

NASA Astrophysics Data System (ADS)

Betskii, O. V.

1994-01-01

The interaction of low-intensity millimeter-band electromagnetic waves with biological objects is examined. These waves are widely used in medical practice as a means of physiotherapy for the treatment of various human disorders. Principal attention is given to the mechanisms through which millimeter waves act on the human organism.

Few millimeter precision for baselines in the California Permanent GPS Geodetic Array

NASA Technical Reports Server (NTRS)

Lindqwister, Ulf J.; Zumberge, James F.; Webb, Frank H.; Blewitt, Geoffrey

1991-01-01

Geodetic measurements with Rogue GPS receivers from sites in the California Permanent GPS geodetic Array (PGGA) have been analyzed using the GIPSY orbit-determination and baseline-estimation software. Based on an unbiased selection of 23 daily measurements spanning 8 months, the LF contributions to the long-term repeatabilities of baseline measurements are approximately 5, 3, and 8 mm for the east, north, and vertical components. Short-term contributions to the long-term repeatabilities were evaluated by examining data from the week of October 21, 1990, which showed the lowest short-term scatter. For this week, daily repeatabilities of 2-3 mm in the horizontal and 4 mm in the vertical have been achieved for the 172-km JPL-Pinyon baseline, consistent with carrier phase date noise of about 6 mm. High quality (less than about 5 mm) repeatabilities have been achieved for all components of the other baselines as well.

Millimeter wave case study of operational deployments: retail, airport, military, courthouse, and customs

NASA Astrophysics Data System (ADS)

Tryon, Gary V.

2008-04-01

In the wake of the September 11, 2001 terrorist attack on America, our security and defense industry was instantly tasked with delivering technologies that could be used to help prevent future terrorist activities. The general public world wide is asking for solutions that will foster a safe society and travel environment. Our best defenses rest in our talents within a free open society to prevent dangerous individuals from boarding planes, entering buildings, courthouses, transportations hubs and military bases with weapons capable of causing damage and bodily harm in the first place. Passive millimeter wave (PMMW) whole body imaging systems are based upon the principle that every physical entity emits, reflects, and/or absorbs electromagnetic energy. The term "passive" means that this approach does not bombard the test subject with energy radiation to further induce the discovery of hidden objects. PMMW whole body imaging systems focus on the human body's natural emission and reflection of millimeter wavelength energy. In physics, "millimeter waves" (MMW) are defined as extremely high-frequency (30-300 GHz) electromagnetic oscillations. On the electromagnetic spectrum these waves are just larger than infrared waves, but smaller than radio waves. The wavelength of a MMW is between 1 millimeter and 10 millimeters. That is approximately the thickness of a large paperclip up to the diameter of an "AAA" battery.

Millimeter wave radar for automobile crash avoidance systems

NASA Astrophysics Data System (ADS)

Huguenin, G. Richard

1994-08-01

Low cost, millimeter wave, forward looking radar sensors for applications in Autonomous Collision Warning and Autonomous Intelligent Cruise Control systems will be described. These safety related systems promise the largest payoff in preventing highway crashes.

EEG changes as heat stress reactions in rats irradiated by high intensity 35 GHz millimeter waves.

PubMed

Xie, Taorong; Pei, Jian; Cui, Yibin; Zhang, Jie; Qi, Hongxing; Chen, Shude; Qiao, Dengjiang

2011-06-01

As the application of millimeter waves for civilian and military use increases, the possibility of overexposure to millimeter waves will also increase. This paper attempts to evaluate stress reactions evoked by 35 GHz millimeter waves. The stress reactions in Sprague-Dawley (SD) rats were quantitatively studied by analyzing electroencephalogram (EEG) changes induced by overexposure to 35 GHz millimeter waves. The relative changes in average energy of the EEG and its wavelet decompositions were used for extracting the stress reaction indicators. Incident average power densities (IAPDs) of 35 GHz millimeter waves from 0.5 W cm(-2) to 7.5 W cm(-2) were employed to investigate the relation between irradiation dose and the stress reactions in the rats. Different stress reaction periods evoked by irradiation were quantitatively evaluated by EEG results. The results illustrate that stress reactions are more intense during the first part of the irradiation than during the later part. The skin temperature increase produced by millimeter wave irradiation is the principle reason for stress reactions and skin injuries. As expected, at the higher levels of irradiation, the reaction time decreases and the reaction intensity increases.

The Very Large Array Data Processing Pipeline

NASA Astrophysics Data System (ADS)

Kent, Brian R.; Masters, Joseph S.; Chandler, Claire J.; Davis, Lindsey E.; Kern, Jeffrey S.; Ott, Juergen; Schinzel, Frank K.; Medlin, Drew; Muders, Dirk; Williams, Stewart; Geers, Vincent C.; Momjian, Emmanuel; Butler, Bryan J.; Nakazato, Takeshi; Sugimoto, Kanako

2018-01-01

We present the VLA Pipeline, software that is part of the larger pipeline processing framework used for the Karl G. Jansky Very Large Array (VLA), and Atacama Large Millimeter/sub-millimeter Array (ALMA) for both interferometric and single dish observations.Through a collection of base code jointly used by the VLA and ALMA, the pipeline builds a hierarchy of classes to execute individual atomic pipeline tasks within the Common Astronomy Software Applications (CASA) package. Each pipeline task contains heuristics designed by the team to actively decide the best processing path and execution parameters for calibration and imaging. The pipeline code is developed and written in Python and uses a "context" structure for tracking the heuristic decisions and processing results. The pipeline "weblog" acts as the user interface in verifying the quality assurance of each calibration and imaging stage. The majority of VLA scheduling blocks above 1 GHz are now processed with the standard continuum recipe of the pipeline and offer a calibrated measurement set as a basic data product to observatory users. In addition, the pipeline is used for processing data from the VLA Sky Survey (VLASS), a seven year community-driven endeavor started in September 2017 to survey the entire sky down to a declination of -40 degrees at S-band (2-4 GHz). This 5500 hour next-generation large radio survey will explore the time and spectral domains, relying on pipeline processing to generate calibrated measurement sets, polarimetry, and imaging data products that are available to the astronomical community with no proprietary period. Here we present an overview of the pipeline design philosophy, heuristics, and calibration and imaging results produced by the pipeline. Future development will include the testing of spectral line recipes, low signal-to-noise heuristics, and serving as a testing platform for science ready data products.The pipeline is developed as part of the CASA software package by an

Open nonradiative cavities as millimeter wave single-mode resonators

NASA Astrophysics Data System (ADS)

Annino, G.; Cassettari, M.; Martinelli, M.

2005-06-01

Open single-mode metallic cavities operating in nonradiative configurations are proposed and demonstrated. Starting from well-known dielectric resonators, possible nonradiative cavities have been established; their behavior on the fundamental TE011 mode has been predicted on the basis of general considerations. As a result, very efficient confinement properties are expected for a wide variety of open structures having rotational invariance. Test cavities realized having in mind practical millimeter wave constraints have been characterized at microwave frequencies. The obtained results confirm the expected high performances on widely open configurations. A possible excitation of the proposed resonators exploiting their nonradiative character is discussed, and the resulting overall ease of realization enlightened in view of millimeter wave employments.

Continuously distributed magnetization profile for millimeter-scale elastomeric undulatory swimming

NASA Astrophysics Data System (ADS)

Diller, Eric; Zhuang, Jiang; Zhan Lum, Guo; Edwards, Matthew R.; Sitti, Metin

2014-04-01

We have developed a millimeter-scale magnetically driven swimming robot for untethered motion at mid to low Reynolds numbers. The robot is propelled by continuous undulatory deformation, which is enabled by the distributed magnetization profile of a flexible sheet. We demonstrate control of a prototype device and measure deformation and speed as a function of magnetic field strength and frequency. Experimental results are compared with simple magnetoelastic and fluid propulsion models. The presented mechanism provides an efficient remote actuation method at the millimeter scale that may be suitable for further scaling down in size for micro-robotics applications in biotechnology and healthcare.

Valley Fever (Coccidioidomycosis) Statistics

MedlinePlus

... Valley fever may be under-recognized. 2 , 3 Public health surveillance for Valley fever Valley fever is reportable ... MMWR) . Check with your local, state, or territorial public health department for more information about disease reporting requirements ...

A Three-Frequency Feed for Millimeter-Wave Radiometry

NASA Technical Reports Server (NTRS)

Hoppe, Daniel J.; Khayatian, Behrouz; Sosnowski, John B.; Johnson, Alan K.; Bruneau, Peter J.

2012-01-01

A three-frequency millimeter-wave feed horn was developed as part of an advanced component technology task that provides components necessary for higher-frequency radiometers to meet the needs of the Surface Water and Ocean Topography (SWOT) mission. The primary objectives of SWOT are to characterize ocean sub-mesoscale processes on 10-km and larger scales in the global oceans, and to measure the global water storage in inland surface water bodies, including rivers, lakes, reservoirs, and wetlands. In this innovation, the feed provides three separate output ports in the 87-to- 97-GHz, 125-to-135-GHz, and 161-to-183- GHz bands; WR10 for the 90-GHz channel, WR8 for the 130-GHz channel, and WR5 for the 170-GHz channel. These ports are in turn connected to individual radiometer channels that will also demonstrate component technology including new PIN-diode switches and noise diodes for internal calibration integrated into each radiometer front end. For this application, a prime focus feed is required with an edge taper of approximately 20 dB at an illumination angle of 40 deg. A single polarization is provided in each band. Preliminary requirements called for a return loss of better than 15 dB, which is achieved across all three bands. Good pattern symmetry is also obtained throughout all three-frequency bands. This three-frequency broadband millimeter-wave feed also minimizes mass and provides a common focal point for all three millimeter-wave bands.

Millimeter imaging of HD 163296: probing the disk structure and kinematics

NASA Astrophysics Data System (ADS)

Isella, A.; Testi, L.; Natta, A.; Neri, R.; Wilner, D.; Qi, C.

2007-07-01

We present new multi-wavelength millimeter interferometric observations of the Herbig Ae star HD 163296 obtained with the IRAM/PBI, SMA and VLA arrays both in continuum and in the 12CO, 13CO and C18O emission lines. Gas and dust properties have been obtained comparing the observations with self-consistent disk models for the dust and CO emission. The circumstellar disk is resolved both in the continuum and in CO. We find strong evidence that the circumstellar material is in Keplerian rotation around a central star of 2.6 M_⊙. The disk inclination with respect to the line of sight is 46° ± 4° with a position angle of 128° ± 4°. The slope of the dust opacity measured between 0.87 and 7 mm (β = 1) confirms the presence of mm/cm-size grains in the disk midplane. The dust continuum emission is asymmetric and confined inside a radius of 200 AU while the CO emission extends up to 540 AU. The comparison between dust and CO temperature indicates that CO is present only in the disk interior. Finally, we obtain an increasing depletion of CO isotopomers from 12CO to 13CO and C18O. We argue that these results support the idea that the disk of HD 163296 is strongly evolved. In particular, we suggest that there is a strong depletion of dust relative to gas outside 200 AU; this may be due to the inward migration of large bodies that form in the outer disk or to clearing of a large gap in the dust distribution by a low mass companion. Based on observations carried out with IRAM Plateau de Bure Interferometer, Submillimeter Array and NRAO Very Large Array. IRAM Plateau de Bure Interferometer is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. The NRAO is a facility of the National Science Foundation operated under cooperative agreement

Valley polarization in bismuth

NASA Astrophysics Data System (ADS)

Fauque, Benoit

2013-03-01

The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

Millimeter-wave Molecular Line Observations of the Tornado Nebula

NASA Astrophysics Data System (ADS)

Sakai, D.; Oka, T.; Tanaka, K.; Matsumura, S.; Miura, K.; Takekawa, S.

2014-08-01

We report the results of millimeter-wave molecular line observations of the Tornado Nebula (G357.7-0.1), which is a bright radio source behind the Galactic center region. A 15' × 15' area was mapped in the J = 1-0 lines of CO, 13CO, and HCO+ with the Nobeyama Radio Observatory 45 m telescope. The Very Large Array archival data of OH at 1720 MHz were also reanalyzed. We found two molecular clouds with separate velocities, V LSR = -14 km s-1 and +5 km s-1. These clouds show rough spatial anti-correlation. Both clouds are associated with OH 1720 MHz emissions in the area overlapping with the Tornado Nebula. The spatial and velocity coincidence indicates violent interaction between the clouds and the Tornado Nebula. Modestly excited gas prefers the position of the Tornado "head" in the -14 km s-1 cloud, also suggesting the interaction. Virial analysis shows that the +5 km s-1 cloud is more tightly bound by self-gravity than the -14 km s-1 cloud. We propose a formation scenario for the Tornado Nebula; the +5 km s-1 cloud collided into the -14 km s-1 cloud, generating a high-density layer behind the shock front, which activates a putative compact object by Bondi-Hoyle-Lyttleton accretion to eject a pair of bipolar jets.

Site characterization at the Rabbit Valley Geophysical Performance Evaluation Range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koppenjan, S,; Martinez, M.

1994-06-01

The United States Department of Energy (US DOE) is developing a Geophysical Performance Evaluation Range (GPER) at Rabbit Valley located 30 miles west of Grand Junction, Colorado. The purpose of the range is to provide a test area for geophysical instruments and survey procedures. Assessment of equipment accuracy and resolution is accomplished through the use of static and dynamic physical models. These models include targets with fixed configurations and targets that can be re-configured to simulate specific specifications. Initial testing (1991) combined with the current tests at the Rabbit Valley GPER will establish baseline data and will provide performance criteriamore » for the development of geophysical technologies and techniques. The US DOE`s Special Technologies Laboratory (STL) staff has conducted a Ground Penetrating Radar (GPR) survey of the site with its stepped FM-CW GPR. Additionally, STL contracted several other geophysical tests. These include an airborne GPR survey incorporating a ``chirped`` FM-CW GPR system and a magnetic survey with a surfaced-towed magnetometer array unit Ground-based and aerial video and still frame pictures were also acquired. STL compiled and analyzed all of the geophysical maps and created a site characterization database. This paper discusses the results of the multi-sensor geophysical studies performed at Rabbit Valley and the future plans for the site.« less

Modal analysis of 2-D sedimentary basin from frequency domain decomposition of ambient vibration array recordings

NASA Astrophysics Data System (ADS)

Poggi, Valerio; Ermert, Laura; Burjanek, Jan; Michel, Clotaire; Fäh, Donat

2015-01-01

Frequency domain decomposition (FDD) is a well-established spectral technique used in civil engineering to analyse and monitor the modal response of buildings and structures. The method is based on singular value decomposition of the cross-power spectral density matrix from simultaneous array recordings of ambient vibrations. This method is advantageous to retrieve not only the resonance frequencies of the investigated structure, but also the corresponding modal shapes without the need for an absolute reference. This is an important piece of information, which can be used to validate the consistency of numerical models and analytical solutions. We apply this approach using advanced signal processing to evaluate the resonance characteristics of 2-D Alpine sedimentary valleys. In this study, we present the results obtained at Martigny, in the Rhône valley (Switzerland). For the analysis, we use 2 hr of ambient vibration recordings from a linear seismic array deployed perpendicularly to the valley axis. Only the horizontal-axial direction (SH) of the ground motion is considered. Using the FDD method, six separate resonant frequencies are retrieved together with their corresponding modal shapes. We compare the mode shapes with results from classical standard spectral ratios and numerical simulations of ambient vibration recordings.

Critical object recognition in millimeter-wave images with robustness to rotation and scale.

PubMed

Mohammadzade, Hoda; Ghojogh, Benyamin; Faezi, Sina; Shabany, Mahdi

2017-06-01

Locating critical objects is crucial in various security applications and industries. For example, in security applications, such as in airports, these objects might be hidden or covered under shields or secret sheaths. Millimeter-wave images can be utilized to discover and recognize the critical objects out of the hidden cases without any health risk due to their non-ionizing features. However, millimeter-wave images usually have waves in and around the detected objects, making object recognition difficult. Thus, regular image processing and classification methods cannot be used for these images and additional pre-processings and classification methods should be introduced. This paper proposes a novel pre-processing method for canceling rotation and scale using principal component analysis. In addition, a two-layer classification method is introduced and utilized for recognition. Moreover, a large dataset of millimeter-wave images is collected and created for experiments. Experimental results show that a typical classification method such as support vector machines can recognize 45.5% of a type of critical objects at 34.2% false alarm rate (FAR), which is a drastically poor recognition. The same method within the proposed recognition framework achieves 92.9% recognition rate at 0.43% FAR, which indicates a highly significant improvement. The significant contribution of this work is to introduce a new method for analyzing millimeter-wave images based on machine vision and learning approaches, which is not yet widely noted in the field of millimeter-wave image analysis.

High temperature superconductor analog electronics for millimeter-wavelength communications

NASA Technical Reports Server (NTRS)

Romanofsky, R. R.; Bhasin, K. B.

1991-01-01

The performance of high temperature superconductor (HTS) passive microwave circuits up to X-band was encouraging when compared to their metallic counterparts. The extremely low surface resistance of HTS films up to about 10 GHz enables a reduction in loss by as much as 100 times compared to copper when both materials are kept at about 77 K. However, a superconductor's surface resistance varies in proportion to the frequency squared. Consequently, the potential benefit of HTS materials to millimeter-wave communications requires careful analysis. A simple ring resonator was used to evaluate microstrip losses at Ka-band. Additional promising components were investigated such as antennas and phase shifters. Prospects for HTS to favorable impact millimeter-wave communications systems are discussed.

Investigation of passive atmospheric sounding using millimeter and submillimeter wavelength channels

NASA Technical Reports Server (NTRS)

Gasiewski, Albin J.; Kunkee, D. B.; Jackson, D. M.; Adelberg, L. K.

1992-01-01

Activities within the period from January 1, 1992 through June 30, 1992 by Georgia Tech researchers in millimeter and submillimeter wavelength tropospheric remote sensing have been centered around the integration and initial data flights of the MIR on board the NASA ER-2. Georgia Tech contributions during this period include completion of the MIR flight software and implementation of a 'quick-view' graphics program for ground based calibration and analysis of the MIR imagery. In the current configuration, the MIR has channels at 90, 150, 183 +/- 1,3,7, and 220 GHz. Provisions for three additional channels at 325 +/-1,3 and 9 GHZ have been made, and a 325-GHz receiver is currently being built by the ZAX Millimeter Wave Corporation for use in the MIR. The combination of the millimeter wave and submillimeter wave channels aboard a single well-calibrated instrument will provide the necessary aircraft radiometric data for radiative transfer and cloud and water vapor retrieval studies. A paper by the PI discussing the potential benefits of passive millimeter and submillimeter wave observations for cloud, water vapor and precipitation measurements has recently been accepted for publication (Gasiewski, 1992), and is included as Appendix A. The MIR instrument is a joint project between NASA/GSFC and Georgia Tech. Other Georgia Tech contributions to the MIR and its related scientific uses have included basic system design studies, performance analyses, and circuit and radiometric load design.

Terrestrial Cosmogenic-Nuclide Dating of Alluvial Fans in Death Valley, California

USGS Publications Warehouse

Machette, Michael N.; Slate, Janet L.; Phillips, Fred M.

2008-01-01

Panamint Valley and over Wingate Wash. A remnant of ancient lake shoreline deposits that once extended across the Hanaupah Canyon fan constrains the timing and extent of the last deep cycle of Pleistocene Lake Manly. The lacustrine delta complex yields a 36Cl depth-profile date of 130 ka, which is consistent with deposition during a highstand of Lake Manly at the end of MIS 6. These deposits are presently at an altitude of about 30 meters above sea level (asl), which relates to a lake with a maximum depth of about 115 meters. Remnants of shoreline deposits at higher elevations on the southern margin of the Hanaupah Canyon fan complex are cut across older alluvium (unit Qao) and may be related to an MIS 6 highstand of at least 67 meters asl or, more likely, an older (MIS 8 or earlier) highstand that is poorly preserved and still undated in the valley. As part of our work on the west-side fans, we also dated an older phase of alluvial-fan deposits from the Trail Canyon fan complex, which is north of Hanaupah Canyon. A 36Cl depth-profile age of 170 ka suggests alluvial deposition of unit Qaio (older phase of Qao) took place prior to the MIS 6 highstand of Lake Manly. Knowing the absolute ages (or range in ages) of the intermediate-age (Qai) surfaces in Death Valley allows us to estimate the following rates of geologic processes: (1) a lateral slip rate of 5 millimeters per year for the northern Death Valley fault zone; (2) uplift of 50 meters in roughly the past 80,000 years for parts of the Mustard Canyon hills in east-central Death Valley; and (3) an estimated 10-40 m of dip-slip thrust movement on the Echo Canyon fault in Furnace Creek Canyon.

Silicon-based antenna-coupled polarization-sensitive millimeter-wave bolometer arrays for cosmic microwave background instruments

NASA Astrophysics Data System (ADS)

Rostem, Karwan; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Brown, Ari; Chang, Meng-Ping; Chuss, David T.; Colazo, Felipe A.; Costen, Nick; Denis, Kevin L.; Essinger-Hileman, Tom; Hu, Ron; Marriage, Tobias A.; Moseley, Samuel H.; Stevenson, Thomas R.; U-Yen, Kongpop; Wollack, Edward J.; Xu, Zhilei

2016-07-01

We describe feedhorn-coupled polarization-sensitive detector arrays that utilize monocrystalline silicon as the dielectric substrate material. Monocrystalline silicon has a low-loss tangent and repeatable dielectric constant, characteristics that are critical for realizing efficient and uniform superconducting microwave circuits. An additional advantage of this material is its low specific heat. In a detector pixel, two Transition-Edge Sensor (TES) bolometers are antenna-coupled to in-band radiation via a symmetric planar orthomode transducer (OMT). Each orthogonal linear polarization is coupled to a separate superconducting microstrip transmission line circuit. On-chip filtering is employed to both reject out-of-band radiation from the upper band edge to the gap frequency of the niobium superconductor, and to flexibly define the bandwidth for each TES to meet the requirements of the application. The microwave circuit is compatible with multi-chroic operation. Metalized silicon platelets are used to define the backshort for the waveguide probes. This micro-machined structure is also used to mitigate the coupling of out-of-band radiation to the microwave circuit. At 40 GHz, the detectors have a measured efficiency of ˜90%. In this paper, we describe the development of the 90 GHz detector arrays that will be demonstrated using the Cosmology Large Angular Scale Surveyor (CLASS) ground-based telescope.

New Insights Into Valley Formation and Preservation: Geophysical Imaging of the Offshore Trinity River Paleovalley

NASA Astrophysics Data System (ADS)

Speed, C. M.; Swartz, J. M.; Gulick, S. P. S.; Goff, J.

2017-12-01

The Trinity River paleovalley is an offshore stratigraphic structure located on the inner continental shelf of the Gulf of Mexico offshore Galveston, Texas. Its formation is linked to the paleo-Trinity system as it existed across the continental shelf during the last glacial period. Newly acquired high-resolution geophysical data have imaged more complexity to the valley morphology and shelf stratigraphy than was previously captured. Significantly, the paleo-Trinity River valley appears to change in the degree of confinement and relief relative to the surrounding strata. Proximal to the modern shoreline, the interpreted time-transgressive erosive surface formed by the paleo-river system is broad and rugose with no single valley, but just 5 km farther offshore the system appears to become confined to a 10 km wide valley structure before again becoming unconfined once again 30 km offshore. Fluvial stratigraphy in this region has a similar degree of complexity in morphology and preservation. A dense geophysical survey of several hundred km is planned for Fall 2017, which will provide unprecedented imaging of the paleovalley morphology and associated stratigraphy. Our analysis leverages robust chirp processing techniques that allow for imaging of strata on the decimeter scale. We will integrate our geophysical results with a wide array of both newly collected and previously published sediment cores. This approach will allow us to address several key questions regarding incised valley formation and preservation on glacial-interglacial timescales including: to what extent do paleo-rivers remain confined within a single broad valley structure, what is the fluvial systems response to transgression, and what stratigraphy is created and preserved at the transition from fluvial to estuarine environments? Our work illustrates that traditional models of incised valley formation and subsequent infilling potentially fail to capture the full breadth of dynamics of past river

Threat detection in desert environment with passive millimeter-wave sensor

NASA Astrophysics Data System (ADS)

Wilson, John P.; Schuetz, Christopher A.; Martin, Richard D.; Dillon, Thomas E.; Murakowski, Maciej; Prather, Dennis W.

2011-06-01

A new technique for improvised explosive device (IED) creation uses an explosive device buried in foam and covered in a layer of dirt. These devices are difficult to detect visually, however, their material characteristics make them detectable by passive millimeter-wave (pmmW) sensors. Results are presented from a test using a mock IED and an outdoor set-up consisting of two mock IEDs on a dirt background. The results show that the mock IEDs produces a millimeter-wave signature which is distinguishable from the background surrounding the mock IEDs. Simulations based on the measured data are presented and a design for a future vehicle mounted sensor is shown.

Realization of a video-rate distributed aperture millimeter-wave imaging system using optical upconversion

NASA Astrophysics Data System (ADS)

Schuetz, Christopher; Martin, Richard; Dillon, Thomas; Yao, Peng; Mackrides, Daniel; Harrity, Charles; Zablocki, Alicia; Shreve, Kevin; Bonnett, James; Curt, Petersen; Prather, Dennis

2013-05-01

Passive imaging using millimeter waves (mmWs) has many advantages and applications in the defense and security markets. All terrestrial bodies emit mmW radiation and these wavelengths are able to penetrate smoke, fog/clouds/marine layers, and even clothing. One primary obstacle to imaging in this spectrum is that longer wavelengths require larger apertures to achieve the resolutions desired for many applications. Accordingly, lens-based focal plane systems and scanning systems tend to require large aperture optics, which increase the achievable size and weight of such systems to beyond what can be supported by many applications. To overcome this limitation, a distributed aperture detection scheme is used in which the effective aperture size can be increased without the associated volumetric increase in imager size. This distributed aperture system is realized through conversion of the received mmW energy into sidebands on an optical carrier. This conversion serves, in essence, to scale the mmW sparse aperture array signals onto a complementary optical array. The side bands are subsequently stripped from the optical carrier and recombined to provide a real time snapshot of the mmW signal. Using this technique, we have constructed a real-time, video-rate imager operating at 75 GHz. A distributed aperture consisting of 220 upconversion channels is used to realize 2.5k pixels with passive sensitivity. Details of the construction and operation of this imager as well as field testing results will be presented herein.

Antenna Electronics Concept for the Next-Generation Very Large Array

NASA Astrophysics Data System (ADS)

Beasley, Anthony J.; Jackson, Jim; Selina, Robert

2017-01-01

The National Radio Astronomy Observatory (NRAO), in collaboration with its international partners, completed two major projects over the past decade: the sensitivity upgrade for the Karl Jansky Very Large Array (VLA) and the construction of the Atacama Large Millimeter/Sub-Millimeter Array (ALMA). The NRAO is now considering the scientific potential and technical feasibility of a next-generation VLA (ngVLA) with an emphasis on thermal imaging at milli-arcsecond resolution. The preliminary goals for the ngVLA are to increase both the system sensitivity and angular resolution of the VLA tenfold and to cover a frequency range of 1.2-116 GHz.A number of key technical challenges have been identified for the project. These include cost-effective antenna manufacturing (in the hundreds), suitable wide-band feed and receiver designs, broad-band data transmission, and large-N correlators. Minimizing the overall operations cost is also a fundamental design requirement.The designs of the antenna electronics, reference distribution system, and data transmission system are anticipated to be major construction and operations cost drivers for the facility. The electronics must achieve a high level of performance, while maintaining low operation and maintenance costs and a high level of reliability. Additionally, due to the uncertainty in the feasibility of wideband receivers, advancements in digitizer technology, and budget constraints, the hardware system architecture should be scalable to the number of receiver bands and the speed and resolution of available digitizers.Here, we present the projected performance requirements of the ngVLA, a proposed block diagram for the instrument’s electronics systems, parameter tradeoffs within the system specifications, and areas of technical risk where technical advances may be required for successful production and installation.

Limits on Arcminute-Scale Cosmic Microwave Background Anisotropy at 28.5 GHz

NASA Technical Reports Server (NTRS)

Holzapfel, W. L.; Carlstrom, J. E.; Grego, L.; Holder, G.; Joy, M.; Reese, E. D.

2000-01-01

We have used the Berkeley-Illinois-Maryland Association (BIMA) millimeter array outfitted with sensitive centimeter-wave receivers to search for cosmic microwave background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration that produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is approximately 6'.6. We have made sensitive images of seven fields, four of which where chosen specifically to have low infrared dust contrast and to be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power of Q(sub flat) = 5.6(sub -5.6)(exp 3.0) microK and Q(sub flat) < 14.1 microK at 68% and 95% confidence, respectively. The sensitivity of this experiment to flat-band power peaks at a multipole of I = 5470, which corresponds to an angular scale of approximately 2'. The most likely value of Q(sub flat) is similar to the level of the expected secondary anisotropies.

Optical manipulation of valley pseudospin

DOE PAGES

Ye, Ziliang; Sun, Dezheng; Heinz, Tony F.

2016-09-19

The coherent manipulation of spin and pseudospin underlies existing and emerging quantum technologies, including quantum communication and quantum computation. Valley polarization, associated with the occupancy of degenerate, but quantum mechanically distinct valleys in momentum space, closely resembles spin polarization and has been proposed as a pseudospin carrier for the future quantum electronics. Valley exciton polarization has been created in the transition metal dichalcogenide monolayers using excitation by circularly polarized light and has been detected both optically and electrically. In addition, the existence of coherence in the valley pseudospin has been identified experimentally. The manipulation of such valley coherence has, however,more » remained out of reach. In this paper, we demonstrate all-optical control of the valley coherence by means of the pseudomagnetic field associated with the optical Stark effect. Using below-bandgap circularly polarized light, we rotate the valley exciton pseudospin in monolayer WSe 2 on the femtosecond timescale. Both the direction and speed of the rotation can be manipulated optically by tuning the dynamic phase of excitons in opposite valleys. Finally, this study unveils the possibility of generation, manipulation, and detection of the valley pseudospin by coupling to photons.« less

Millimeter-wave MMIC technology for smart weapons

NASA Astrophysics Data System (ADS)

Seashore, Charles R.

1994-12-01

Millimeter wave MMIC component technology has made dramatic progress over the last ten years largely due to funding stimulation received under the ARPA Tri-Service MIMIC program. In several smart weapon systems, MMIC components are now specified as the baseline approach for millimeter wave radar transceiver hardware. Availability of this new frontier in microelectronics has also enabled realization of sensor fusion for multispectral capability to defeat many forms of known countermeasures. The current frequency range for these MMIC-based components is approximately 30 to 100 GHz. In several cases, it has been demonstrated that the MMIC component performance has exceeded that available from hybrid microstrip circuits using selected discrete devices. However, challenges still remain in chip producibility enhancement and cost reduction since many of the essential device structure candidates are themselves emerging technologies with a limited wafer fabrication history and accumulated test databases. It is concluded that smart weapons of the future will rely heavily on advanced microelectronics to satisfy performance requirements as well as meeting stringent packaging and power source constraints.

Seismicity of the Wabash Valley, Ste. Genevieve, and Rough Creek Graben Seismic Zones from the Earthscope Ozarks-Illinois-Indiana-Kentucky (OIINK) FlexArray Experiment

NASA Astrophysics Data System (ADS)

Shirley, Matthew Richard

I analyzed seismic data from the Ozarks-Illinois-Indiana-Kentucky (OIINK) seismic experiment that operated in eastern Missouri, southern Illinois, southern Indiana, and Kentucky from July 2012 through March 2015. A product of this analysis is a new catalog of earthquake locations and magnitudes for small-magnitude local events during this study period. The analysis included a pilot study involving detailed manual analysis of all events in a ten-day test period and determination of the best parameters for a suite of automated detection and location programs. I eliminated events that were not earthquakes (mostly quarry and surface mine blasts) from the output of the automated programs, and reprocessed the locations for the earthquakes with manually picked P- and S-wave arrivals. This catalog consists of earthquake locations, depths, and local magnitudes. The new catalog consists of 147 earthquake locations, including 19 located within the bounds of the OIINK array. Of these events, 16 were newly reported events, too small to be reported in the Center for Earthquake Research and Information (CERI) regional seismic network catalog. I compared the magnitudes reported by CERI for corresponding earthquakes to establish a magnitude calibration factor for all earthquakes recorded by the OIINK array. With the calibrated earthquake magnitudes, I incorporate the previous OIINK results from Yang et al. (2014) to create magnitude-frequency distributions for the seismic zones in the region alongside the magnitude-frequency distributions made from CERI data. This shows that Saint Genevieve and Wabash Valley seismic zones experience seismic activity at an order magnitude lower rate than the New Madrid seismic zone, and the Rough Creek Graben experiences seismic activity two orders of magnitude less frequently than New Madrid.

THE CHROMOSPHERIC SOLAR LIMB BRIGHTENING AT RADIO, MILLIMETER, SUB-MILLIMETER, AND INFRARED WAVELENGTHS

DOE Office of Scientific and Technical Information (OSTI.GOV)

De la Luz, V.

2016-07-10

Observations of the emission at radio, millimeter, sub-millimeter, and infrared wavelengths in the center of the solar disk validate the autoconsistence of semi-empirical models of the chromosphere. Theoretically, these models must reproduce the emission at the solar limb. In this work, we tested both the VALC and C7 semi-empirical models by computing their emission spectrum in the frequency range from 2 GHz to 10 THz at solar limb altitudes. We calculate the Sun's theoretical radii as well as their limb brightening. Non-local thermodynamic equilibrium was computed for hydrogen, electron density, and H{sup −}. In order to solve the radiative transfermore » equation, a three-dimensional (3D) geometry was employed to determine the ray paths, and Bremsstrahlung, H{sup −}, and inverse Bremsstrahlung opacity sources were integrated in the optical depth. We compared the computed solar radii with high-resolution observations at the limb obtained by Clark. We found that there are differences between the observed and computed solar radii of 12,000 km at 20 GHz, 5000 km at 100 GHz, and 1000 km at 3 THz for both semi-empirical models. A difference of 8000 km in the solar radii was found when comparing our results against the heights obtained from H α observations of spicules-off at the solar limb. We conclude that the solar radii cannot be reproduced by VALC and C7 semi-empirical models at radio—infrared wavelengths. Therefore, the structures in the high chromosphere provide a better measurement of the solar radii and their limb brightening as shown in previous investigations.« less

Josephson junction spectrum analyzer for millimeter and submillimeter wavelengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larkin, S.Y.; Anischenko, S.E.; Khabayev, P.V.

1994-12-31

A prototype of the Josephson-effect spectrum analyzer developed for the millimeter-wave band is described. The measurement results for spectra obtained in the frequency band from 50 to 250 GHz are presented.

Josephson Junction spectrum analyzer for millimeter and submillimeter wavelengths

NASA Technical Reports Server (NTRS)

Larkin, S. Y.; Anischenko, S. E.; Khabayev, P. V.

1995-01-01

A prototype of the Josephson-effect spectrum analyzer developed for the millimeter wave band is described. The measurement results for spectra obtained in the frequency band from 50 to 250 GHz are presented.

A Robust Waveguide Millimeter-Wave Noise Source

NASA Technical Reports Server (NTRS)

Ehsan, Negar; Piepmeier, Jeffrey R.; Solly, Michael; Macmurphy, Shawn; Lucey, Jared; Wollack, Edward

2015-01-01

This paper presents the design, fabrication, and characterization of a millimeter-wave noise source for the 160- 210 GHz frequency range. The noise source has been implemented in an E-split-block waveguide package and the internal circuitry was developed on a quartz substrate. The measured excess noise ratio at 200 GHz is 9.6 dB.

Subsurface Constraints on Late Cenozoic Basin Geometry in Northern Fish Lake Valley and Displacement Transfer Along the Northern Fish Lake Valley Fault Zone, Western Nevada

NASA Astrophysics Data System (ADS)

Mueller, N.; Kerstetter, S. R.; Katopody, D. T.; Oldow, J. S.

2016-12-01

The NW-striking, right-oblique Fish Lake Valley fault zone (FLVFZ) forms the northern segment of the longest active structure in the western Great Basin; the Death Valley - Furnace Creek - Fish Lake Valley fault system. Since the mid-Miocene, 50 km of right-lateral displacement is documented on the southern FLVFZ and much of that displacement was and is transferred east and north on active WNW left-lateral faults. Prior to the Pliocene, displacement was transferred east and north on a low-angle detachment. Displacement on the northern part of the FLVFZ continues and is transferred to a fanned array of splays striking (west to east) WNW, NNW, ENE and NNE. To determine the displacement budget on these structures, we conducted a gravity survey to determine subsurface basin morphology and its relation to active faults. Over 2450 stations were collected and combined with existing PACES and proprietary data for a total of 3388 stations. The data were terrain corrected and reduced to a 2.67 g/cm3 density to produce a residual complete Bouguer anomaly. The eastern part of northern Fish Lake Valley is underlain by several prominent gravity lows forming several sub-basins with maximum RCBA values ranging from -24 to -28 mGals. The RCBA was inverted for depth using Geosoft Oasis Montaj GM-SYS 3D modeling software. Density values for the inversion were constrained by lithologic and density logs from wells that penetrate the entire Cenozoic section into the Paleozoic basement. Best fitting gravity measurements taken at the wellheads yielded an effective density of 2.4 g/cm3 for the basin fill. Modeled basement depths range between 2.1 to 3 km. The sub-basins form an arc opening to the NW and are bounded by ENE and NNE faults in the south and NS to NNW in the north. At the northern end of the valley, the faults merge with ENE left-lateral strike slip faults of the Mina deflection, which carries displacement to NW dextral strike-slip faults of the central Walker Lane.

Millimeter-Wave GaN MMIC Integration with Additive Manufacturing

NASA Astrophysics Data System (ADS)

Coffey, Michael

This thesis addresses the analysis, design, integration and test of microwave and millimeter-wave monolithic microwave integrated circuits (MMIC or MMICs). Recent and ongoing progress in semiconductor device fabrication and MMIC processing technology has pushed the upper limit in MMIC frequencies from millimeter-wave (30-300 GHz) to terahertz (300-3000 GHz). MMIC components operating at these frequencies will be used to improve the sensitivity and performance of radiometers, receivers for communication systems, passive remote sensing systems, transceivers for radar instruments and radio astronomy systems. However, a serious hurdle in the utilization of these MMIC components, and a main topic presented in this thesis, is the development and reliable fabrication of practical packaging techniques. The focus of this thesis is the investigation of first, the design and analysis of microwave and millimeter-wave GaN MMICs and second, the integration of those MMICs into usable waveguide components. The analysis, design and testing of various X-band (8-12 GHz) thru H-band (170-260 GHz) GaN MMIC power amplifier (PA or PAs), including a V-band (40-75 GHz) voltage controlled oscillator, is the majority of this work. Several PA designs utilizing high-efficiency techniques are analyzed, designed and tested. These examples include a 2nd harmonic injection amplifier, a Class-E amplifier fabricated with a GaN-on-SiC 300 GHz fT process, and an example of the applicability of supply-modulation with a Doherty power amplifier, all operating at 10 GHz. Two H-band GaN MMIC PAs are designed, one with integrated CPW-to-waveguide transitions for integration. The analysis of PA stability is especially important for wideband, high- fT devices and a new way of analyzing stability is explored and experimentally validated. Last, the challenges of integrating MMICs operating at millimeter-wave frequencies are discussed and assemblies using additive and traditional manufacturing are demonstrated.

Design and development of a multifunction millimeter wave sensor

NASA Astrophysics Data System (ADS)

Nadimi, Sayyid Abdolmajid

1998-11-01

The millimeter-wave (MMW) spectrum (30-300 GHz) offers a unique combination of features that are advantageous when retrieving information about the environment. Due to small wavelengths involved, physically small antennas may be used to obtain very high gains (>50 dB) and resulting high spatial resolutions. Moreover, some features have scattering and emission behaviors that are more sensitive at MMW wavelengths than at microwave wavelengths. Examples include, water vapor (H2O). fog, haze, clouds, ozone (O 3) molecules, and chlorine monoxide (ClO) have rotational spectra in this region. The 75-110 GHz (W-band) atmospheric window is relatively quiet, and it can supply spectral information that can be useful in identifying and quantifying pollutants. Information such as the size and concentration of particulate pollutants can be obtained using radar techniques at W-band. Although there have been some activities at millimeter wave frequencies over very narrow bandwidths, there is a great need for wider bandwidth instruments for studying scattering and emission behaviors. To address this need and provide a versatile system for laboratory studies of electromagnetic phenomena at millimeter-wave frequencies, a multifunctionmillimeter- wave sensor has been designed and developed. This instrument is an active/passive wide band sensor operating in the 75-110 GHz region of the millimeter wave spectrum in four primary modes: (1)As a spectrometer measuring absorption over the entire 75-110 GHz region. (2)As a radiometer measuring blackbody emissions over the entire 75-110 GHz region. (3)As a pulse radar over a 500 MHz bandwidth centered around 93.1 GHz with a peak power of 200 mW. (4)As a step frequency radar when used in combination with a network analyzer over selected 9 GHz bandwidth segments (75-84, 84-93, 93-102, and 102-110) of the 75-110 GHz region. Measurements were performed on two volume fraction (15% and 20%) dense random media targets using this system. The results

Investigation of passive atmospheric sounding using millimeter and submillimeter wavelength channels

NASA Technical Reports Server (NTRS)

Gasiewski, A. J.; Adelberg, L. K.; Kunkee, D. B.; Jackson, D. M.

1993-01-01

Progress by investigators at the Georgia Institute of Technology in the development of techniques for passive microwave retrieval of water vapor, cloud, and precipitation parameters using millimeter- and sub-millimeter wavelength channels is reviewed. Channels of particular interest are in the tropospheric transmission windows at 90, 166, 220, 340, and 410 GHz and centered around the water vapor lines at 183 and 325 GHz. Collectively, these channels have potential application in high-resolution mapping (e.g., from geosynchronous orbit), remote sensing of cloud and precipitation parameters, and retrieval of water vapor profiles. During the period from 1 Jan. 1993 through 30 Jun. 1993 the Millimeter-wave Imaging Radiometer (MIR) completed data flights during a two-month long deployment in conjunction with TOGA/COARE. Coincident data was collected from several other ground-based, airborne, and satellite sensors, including the NASA/MSFC AMPR, MIT MTS, DMSP SSM/T-2 satellite, collocated radiosondes, ground- and aircraft-based radiometers and cloud lidars, airborne infrared imagers, solar flux probes, and airborne cloud particle sampling probes.

PNNL Expert Doug McMakin Discusses Millimeter Wave Technology

ScienceCinema

McMakin, Doug

2018-02-13

Electrical Engineer Doug McMakin discusses Millimeter Wave Holographic technology, which uses non-harmful, ultrahigh-frequency radio waves to penetrate clothing to detect and identify concealed objects, as well as obtain accurate body measurements.

Effects of Different Types of Burn Wounds and its Dressings on Millimeter-Wave Images

NASA Astrophysics Data System (ADS)

Daniel, Oppelt; Patrick, Korf; Julian, Adametz; Jannis, Groh; Martin, Vossiek; Kristina, Zhuravleva; Ole, Goertz

2018-03-01

Millimeter-wave imaging is a promising technology for diagnosing skin burns, that may make it easier to assess and determine the burn depth in the near future. However, up to now, it has not yet been brought to clinical use due to the lack of clinical trails on patients and a millimeter-wave-aided classification of skin burns. In this paper, in a preliminary step, ex-vivo burned porcine skin is utilized to visualize and quantify skin that has been burned in different ways, and to access its effect on millimeter-wave images. For the first time, a 24 hour study of in-vivo human skin visualizes the effect of wound dressings using a fast imaging system operating at frequencies from 70 to 80 GHz. For validation, the effective relative permittivity of the skin and the dressings are measured using a open-ended coaxial probe. An analytical model is applied to calculate the reflection coefficient which are compared to the intensity of the millimeter-wave images to validate the model.

Massive formation of square array junctions dramatically alters cell shape but does not cause lens opacity in the cav1-KO mice.

PubMed

Biswas, Sondip K; Brako, Lawrence; Lo, Woo-Kuen

2014-08-01

The wavy square array junctions are composed of truncated aquaporin-0 (AQP0) proteins typically distributed in the deep cortical and nuclear fibers in wild-type lenses. These junctions may help maintain the narrowed extracellular spaces between fiber cells to minimize light scattering. Herein, we investigate the impact of the cell shape changes, due to abnormal formation of extensive square array junctions, on the lens opacification in the caveolin-1 knockout mice. The cav1-KO and wild-type mice at age 1-22 months were used. By light microscopy examinations, cav1-KO lenses at age 1-18 months were transparent in both cortical and nuclear regions, whereas some lenses older than 18 months old exhibited nuclear cataracts. Scanning EM consistently observed the massive formation of ridge-and-valley membrane surfaces in young fibers at approximately 150 μm deep in all cav1-KO lenses studied. In contrast, the typical ridge-and-valleys were only seen in mature fibers deeper than 400 μm in wild-type lenses. The resulting extensive ridge-and-valleys dramatically altered the overall cell shape in cav1-KO lenses. Remarkably, despite dramatic shape changes, these deformed fiber cells remained intact and made close contact with their neighboring cells. By freeze-fracture TEM, ridge-and-valleys exhibited the typical orthogonal arrangement of 6.6 nm square array intramembrane particles and displayed the narrowed extracellular spaces. Immunofluorescence analysis showed that AQP0 C-terminus labeling was significantly decreased in outer cortical fibers in cav1-KO lenses. However, freeze-fracture immunogold labeling showed that the AQP0 C-terminus antibody was sparsely distributed on the wavy square array junctions, suggesting that the cleavage of AQP0 C-termini might not yet be complete. The cav1-KO lenses with nuclear cataracts showed complete cellular breakdown and large globule formation in the lens nucleus. This study suggests that despite dramatic cell shape changes, the

Experimental Phase Functions of Millimeter-sized Cosmic Dust Grains

NASA Astrophysics Data System (ADS)

Muñoz, O.; Moreno, F.; Vargas-Martín, F.; Guirado, D.; Escobar-Cerezo, J.; Min, M.; Hovenier, J. W.

2017-09-01

We present the experimental phase functions of three types of millimeter-sized dust grains consisting of enstatite, quartz, and volcanic material from Mount Etna, respectively. The three grains present similar sizes but different absorbing properties. The measurements are performed at 527 nm covering the scattering angle range from 3° to 170°. The measured phase functions show two well-defined regions: (I) soft forward peaks and (II) a continuous increase with the scattering angle at side- and back-scattering regions. This behavior at side- and back-scattering regions is in agreement with the observed phase functions of the Fomalhaut and HR 4796A dust rings. Further computations and measurements (including polarization) for millimeter-sized grains are needed to draw some conclusions about the fluffy or compact structure of the dust grains.

A Ka-Band (26 GHz) Circularly Polarized 2x2 Microstrip Patch Sub-Array with Compact Feed

NASA Technical Reports Server (NTRS)

Chrysler, Andrew; Furse, Cynthia; Simons, Rainee N.; Miranda, Felix A.

2017-01-01

A Ka-Band (26 gigahertz) 2 by 2 sub-array with square-shaped microstrip patch antenna elements having two truncated corners for circular polarization (CP) is presented. In addition, the layout for a new compact microstrip feed network for the sub-array is also presented. The compact feed network offers a footprint size reduction of near 60 percent over traditional sub-array at 26 gigahertz. Experimental data indicates that a truncation amount a equals 0.741 millimeters for an isolated patch element results in a return loss (S (sub II)) of minus 35 decibels at 26.3 gigahertz. Furthermore, the measured S (sub II) for the proof-of-concept sub-array with the above elements is better than minus 10.0 decibels at 27.7 gigahertz. However, the impedance match and the operating frequency can be fine-tuned to 26 gigahertz by adjusting the feed network dimensions. Lastly, good agreement is observed between the measured and simulated S (sub II) for the subarray for both right hand and left hand CP. The goal of this effort is utilize the above sub-array as a building block for a larger N by N element array, which would serve as a feed for a reflector antenna for satellite communications.

Chuckwalla Valley multiple-well monitoring site, Chuckwalla Valley, Riverside County

USGS Publications Warehouse

Everett, Rhett

2013-01-01

The U.S. Geological Survey (USGS), in cooperation with the Bureau of Land Management, is evaluating the geohydrology and water availability of the Chuckwalla Valley, California. As part of this evaluation, the USGS installed the Chuckwalla Valley multiple-well monitoring site (CWV1) in the southeastern portion of the Chuckwalla Basin. Data collected at this site provide information about the geology, hydrology, geophysics, and geochemistry of the local aquifer system, thus enhancing the understanding of the geohydrologic framework of the Chuckwalla Valley. This report presents construction information for the CWV1 multiple-well monitoring site and initial geohydrologic data collected from the site.

Mutual capacitance of liquid conductors in deformable tactile sensing arrays

NASA Astrophysics Data System (ADS)

Li, Bin; Fontecchio, Adam K.; Visell, Yon

2016-01-01

Advances in highly deformable electronics are needed in order to enable emerging categories of soft computing devices ranging from wearable electronics, to medical devices, and soft robotic components. The combination of highly elastic substrates with intrinsically stretchable conductors holds the promise of enabling electronic sensors that can conform to curved objects, reconfigurable displays, or soft biological tissues, including the skin. Here, we contribute sensing principles for tactile (mechanical image) sensors based on very low modulus polymer substrates with embedded liquid metal microfluidic arrays. The sensors are fabricated using a single-step casting method that utilizes fine nylon filaments to produce arrays of cylindrical channels on two layers. The liquid metal (gallium indium alloy) conductors that fill these channels readily adopt the shape of the embedding membrane, yielding levels of deformability greater than 400%, due to the use of soft polymer substrates. We modeled the sensor performance using electrostatic theory and continuum mechanics, yielding excellent agreement with experiments. Using a matrix-addressed capacitance measurement technique, we are able to resolve strain distributions with millimeter resolution over areas of several square centimeters.

Target contrast considerations in millimeter wave radiometry for airborne navigation

NASA Technical Reports Server (NTRS)

Mayer, A.

1971-01-01

Target signal requirements for aircraft navigation systems that use radiometric receivers which map thermally emitted power radiated by terrain or power radiated by ground-based beacons are discussed. For selected millimeter wavelength bands, microwaves suffer relatively little degradation by absorption or scattering on passage through the atmosphere, despite extreme weather variations. Interest centers on 8-millimeter waves because of component availability, portability (small size), high image resolution, and all-weather capability at this wavelength. The idea of radiometric airborne navigation is introduced. Elements of radiometry, terrain radiation, and atmospheric transmission characteristics are reviewed. Data pertaining to these elements at 8 mm wavelength are collected. Calculation of radiometric contrasts is discussed for some simple models of terrain targets.

Space propulsion and power beaming using millimeter systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benford, J.; Dickinson, R.

1995-11-01

Past schemes for using beamed microwave power for space propulsion and providing power to space platforms have used microwaves below 10 GHz. Recent expansions of the high power microwave technology domain offer fundamental reassessment of the following missions: (1) location of orbital debris, (2) supplying power to loitering high-altitude airplanes, (3) satellite battery recharging, (4) imaging of asteroids, (5) orbit raising and transfer, (6) interplanetary probe launch to the outer planets and comets, and ultimately (7) launch into Earth orbit. This group of applications may be done by a ground-based system. The system would start small, being built for themore » near Earth missions, and be enlarged incrementally as the technology matures and confidence develops. Of particular interest are sources in the millimeter range where there are low loss atmospheric windows and MJ pulses are available in quasi-CW operation. A development scenario for these missions using millimeter wave technology is described.« less

Millimeter image of the HL Tau Disk: gaps opened by planets?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hui

2015-10-20

Several observed features which favor planet-induced gaps in the disk are pointed out. Parameters of a two-fluid simulation model are listed, and some model results are shown. It is concluded that (1) interaction between planets, gas, and dust can explain the main features in the ALMA observation; (2) the millimeter image of a disk is determined by the dust profile, which in turn is influenced by planetary masses, viscosity, disk self-gravity, etc.; and (3) models that focus on the complex physics between gas and dust (and planets) are crucial in interpreting the (sub)millimeter images of disks.

Sacramento Valley, CA, USA

NASA Technical Reports Server (NTRS)

1973-01-01

The Sacramento Valley (40.5N, 121.5W) of California is the northern extension of the Central Valley, main agriculture region of the state. Hundreds of truck farms, vineyards and orchards can be seen throughout the length and breadth of the valley which was reclaimed from the desert by means of intensive and extensive irrigation projects.

Generation of Optical Millimeter Wave Using Two Cascaded Polarization Modulators Based on Frequency Octupling Without Filtering

NASA Astrophysics Data System (ADS)

Yang, Yang; Ma, Jianxin; Zhang, Ruijiao; Xin, Xiangjun; Zhang, Junyi

2015-11-01

An approach to generate an optical millimeter wave is introduced with frequency octupling using two cascaded polarization modulators followed by polarizers, respectively. By adjusting the modulation indexes of polarization modulators, only the ±4th-order sidebands are generated with a pure spectrum. Since no filter is needed, the proposed technique can be used to generate a frequency-tunable millimeter wave with a large frequency-tunable range. To prove the feasibility of the proposed approach, a simulation is conducted to generate an 80-GHz millimeter wave, and then its transmission performance is checked.

3D-Printed Millimeter Wave Structures

DTIC Science & Technology

2016-03-14

demonstrates the resolution of the printer with a 10 micron nozzle. Figure 2: Measured loss tangent of SEBS and SBS samples. 3D - Printed Millimeter... 3D printing of styrene-butadiene-styrene (SBS) and styrene ethylene/butylene-styrene (SEBS) is used to demonstrate the feasibility of 3D - printed ...Additionally, a dielectric lens is printed which improves the antenna gain of an open-ended WR-28 waveguide from 7 to 8.5 dBi. Keywords: 3D printing

Millimeter-Visible Injection Locking and Testing.

DTIC Science & Technology

1985-12-01

Fetterman , Chewlan Liew, & Wai-Leung Ngai 13a. TYPE OF REPORT 13b. TIME COVERED i 4. DATE OF REPORT (Year, Month, Day) I 5. PAGE COUNT FINAL FROM I Jan...HAROLD FETTERMAN > Accesior For NTIS CA&I DTIC TAB El Unr-no,: :ed [- SJ :st tt:C at i: .. ... ................... B y...Dist, 6btitior; I Av.-),! *j I Of Dist - -206 5 1 Millimeter-Visible Injection Locking and Testing Harold Fetterman , Chewlan Liew, and Wai-Leung

Experimental Phase Functions of Millimeter-sized Cosmic Dust Grains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muñoz, O.; Moreno, F.; Guirado, D.

We present the experimental phase functions of three types of millimeter-sized dust grains consisting of enstatite, quartz, and volcanic material from Mount Etna, respectively. The three grains present similar sizes but different absorbing properties. The measurements are performed at 527 nm covering the scattering angle range from 3° to 170°. The measured phase functions show two well-defined regions: (i) soft forward peaks and (ii) a continuous increase with the scattering angle at side- and back-scattering regions. This behavior at side- and back-scattering regions is in agreement with the observed phase functions of the Fomalhaut and HR 4796A dust rings. Furthermore » computations and measurements (including polarization) for millimeter-sized grains are needed to draw some conclusions about the fluffy or compact structure of the dust grains.« less

Monitoring of Microseismicity with ArrayTechniques in the Peach Tree Valley Region

NASA Astrophysics Data System (ADS)

Garcia-Reyes, J. L.; Clayton, R. W.

2016-12-01

This study is focused on the analysis of microseismicity along the San Andreas Fault in the PeachTree Valley region. This zone is part of the transition zone between the locked portion to the south (Parkfield, CA) and the creeping section to the north (Jovilet, et al., JGR, 2014). The data for the study comes from a 2-week deployment of 116 Zland nodes in a cross-shaped configuration along (8.2 km) and across (9 km) the Fault. We analyze the distribution of microseismicity using a 3D backprojection technique, and we explore the use of Hidden Markov Models to identify different patterns of microseismicity (Hammer et al., GJI, 2013). The goal of the study is to relate the style of seismicity to the mechanical state of the Fault. The results show the evolution of seismic activity as well as at least two different patterns of seismic signals.

Sacramento Valley, CA, USA

NASA Image and Video Library

1973-06-22

SL2-04-179 (22 June 1973) --- The Sacramento Valley (40.5N, 121.5W) of California is the northern extension of the Central Valley, main agriculture region of the state. Hundreds of truck farms, vineyards and orchards can be seen throughout the length and breadth of the valley which was reclaimed from the desert by means of intensive and extensive irrigation projects. Photo credit: NASA

Land subsidence, groundwater levels, and geology in the Coachella Valley, California, 1993-2010

USGS Publications Warehouse

Sneed, Michelle; Brandt, Justin T.; Solt, Mike

2014-01-01

Land subsidence associated with groundwater-level declines has been investigated by the U.S. Geological Survey in the Coachella Valley, California, since 1996. Groundwater has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of groundwater resulted in water-level declines as much as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in groundwater pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated groundwater-level declines and, consequently, an increase in the potential for land subsidence caused by aquifer-system compaction. Global Positioning System (GPS) surveying and Interferometric Synthetic Aperture Radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley during 1993–2010. The GPS measurements taken at 11 geodetic monuments in 1996 and in 2010 in the southern Coachella Valley indicated that the elevation of the land surface changed –136 to –23 millimeters (mm) ±54 mm (–0.45 to –0.08 feet (ft) ±0.18 ft) during the 14-year period. Changes at 6 of the 11 monuments exceeded the maximum expected uncertainty of ±54 mm (±0.18 ft) at the 95-percent confidence level, indicating that subsidence occurred at these monuments between June 1996 and August 2010. GPS measurements taken at 17 geodetic monuments in 2005 and 2010 indicated that the elevation of the land surface changed –256 to +16 mm ±28 mm (–0.84 to +0.05 ft ±0.09 ft) during the 5-year period. Changes at 5 of the 17 monuments exceeded the maximum expected uncertainty of ±28 mm (±0.09 ft) at the 95-percent confidence level, indicating that subsidence occurred

System-Level Integrated Circuit (SLIC) development for phased array antenna applications

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Raquet, C. A.

1991-01-01

A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

System-level integrated circuit (SLIC) development for phased array antenna applications

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Raquet, C. A.

1991-01-01

A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

Observation of acoustic valley vortex states and valley-chirality locked beam splitting

NASA Astrophysics Data System (ADS)

Ye, Liping; Qiu, Chunyin; Lu, Jiuyang; Wen, Xinhua; Shen, Yuanyuan; Ke, Manzhu; Zhang, Fan; Liu, Zhengyou

2017-05-01

We report an experimental observation of the classical version of valley polarized states in a two-dimensional hexagonal sonic crystal. The acoustic valley states, which carry specific linear momenta and orbital angular momenta, were selectively excited by external Gaussian beams and conveniently confirmed by the pressure distribution outside the crystal, according to the criterion of momentum conservation. The vortex nature of such intriguing bulk crystal states was directly characterized by scanning the phase profile inside the crystal. In addition, we observed a peculiar beam-splitting phenomenon, in which the separated beams are constructed by different valleys and locked to the opposite vortex chirality. The exceptional sound transport, encoded with valley-chirality locked information, may serve as the basis of designing conceptually interesting acoustic devices with unconventional functions.

Development and Testing of a Refractory Millimeter-Wave Absorbent Heat Exchanger

NASA Technical Reports Server (NTRS)

Lambot, Thomas; Myrabo, Leik; Murakami, David; Parkin, Kevin

2014-01-01

Central to the Millimeter-Wave Thermal Launch System (MTLS) is the millimeter-wave absorbent heat exchanger. We have developed metallic and ceramic variants, with the key challenge being the millimeter-wave absorbent coatings for each. The ceramic heat exchanger came to fruition first, demonstrating for the first time 1800 K peak surface temperatures under illumination by a 110 GHz Gaussian beam. Absorption efficiencies of up to 80 are calculated for mullite heat exchanger tubes and up to 50 are calculated for alumina tubes. These are compared with estimates based on stratified layer and finite element analyses. The problem of how to connect the 1800 K end of the ceramic tubes to a graphite outlet manifold and nozzle is solved by press fitting, or by threading the ends of the ceramic tubes and screwing them into place. The problem of how to connect the ceramic tubes to a metallic or nylon inlet pipe is solved by using soft compliant PTFE and PVC tubes that accommodate thermal deformations of the ceramic tubes during startup and operation. We show the resulting heat exchangers in static tests using argon and helium as propellants.

Chromosphere Active Region Plasma Diagnostics Based On Observations Of Millimeter Radiation

NASA Astrophysics Data System (ADS)

Loukitcheva, M.; Nagnibeda, V.

1999-10-01

In this paper we present the results of millimeter radiation calculations for different elements of chromospheric and transition region structures of the quiet Sun and S-component - elements of chromosphere network, sunspot groups and plages. The calculations were done on the basis of standard optical and UV models ( models by Vernazza et al. (1981,VAL), their modifications by Fontenla et al. (1993,FAL)). We also considered the sunspot model by Lites and Skumanich (1982,LS), S-component model by Staude et al.(1984) and modification of VAL and FAL models by Bocchialini and Vial - models NET and CELL. We compare these model calculations with observed characteristics of components of millimeter Solar radiation for the quiet Sun and S-component obtained with the radiotelescope RT-7.5 MGTU (wavelength 3.4 mm) and radioheliograph Nobeyama (wavelength 17.6 mm). From observations we derived spectral characteristics of millimeter sources and active region source structure. The comparison has shown that observed radio data are clearly in dissagrement with all the considered models. Finally, we propose further improvement of chromospheric and transition region models based on optical and UV observations in order to use for modelling information obtained from radio data.

Millimeter transient point sources in the SPTpol 100 square degree survey

DOE PAGES

Whitehorn, N.; Natoli, T.; Ade, P. A. R.; ...

2016-10-18

The millimeter transient sky is largely unexplored, with measurements limited to follow-up of objects detected at other wavelengths. High-angular-resolution telescopes, designed for measurement of the cosmic microwave background (CMB), offer the possibility to discover new, unknown transient sources in this band—particularly the afterglows of unobserved gamma-ray bursts (GRBs). Here, we use the 10 m millimeter-wave South Pole Telescope, designed for the primary purpose of observing the CMB at arcminute and larger angular scales, to conduct a search for such objects. During the 2012–2013 season, the telescope was used to continuously observe a 100 deg 2 patch of sky centered atmore » R.A. 23 h30 m and decl. –55° using the polarization-sensitive SPTpol camera in two bands centered at 95 and 150 GHz. These 6000 hr of observations provided continuous monitoring for day- to month-scale millimeter-wave transient sources at the 10 mJy level. As a result, one candidate object was observed with properties broadly consistent with a GRB afterglow, but at a statistical significance too low (p = 0.01) to confirm detection.« less

MILLIMETER TRANSIENT POINT SOURCES IN THE SPTpol 100 SQUARE DEGREE SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitehorn, N.; Haan, T. de; George, E. M.

The millimeter transient sky is largely unexplored, with measurements limited to follow-up of objects detected at other wavelengths. High-angular-resolution telescopes, designed for measurement of the cosmic microwave background (CMB), offer the possibility to discover new, unknown transient sources in this band—particularly the afterglows of unobserved gamma-ray bursts (GRBs). Here, we use the 10 m millimeter-wave South Pole Telescope, designed for the primary purpose of observing the CMB at arcminute and larger angular scales, to conduct a search for such objects. During the 2012–2013 season, the telescope was used to continuously observe a 100 deg{sup 2} patch of sky centered atmore » R.A. 23{sup h}30{sup m} and decl. −55° using the polarization-sensitive SPTpol camera in two bands centered at 95 and 150 GHz. These 6000 hr of observations provided continuous monitoring for day- to month-scale millimeter-wave transient sources at the 10 mJy level. One candidate object was observed with properties broadly consistent with a GRB afterglow, but at a statistical significance too low ( p = 0.01) to confirm detection.« less

Millimeter transient point sources in the SPTpol 100 square degree survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitehorn, N.; Natoli, T.; Ade, P. A. R.

The millimeter transient sky is largely unexplored, with measurements limited to follow-up of objects detected at other wavelengths. High-angular-resolution telescopes, designed for measurement of the cosmic microwave background (CMB), offer the possibility to discover new, unknown transient sources in this band—particularly the afterglows of unobserved gamma-ray bursts (GRBs). Here, we use the 10 m millimeter-wave South Pole Telescope, designed for the primary purpose of observing the CMB at arcminute and larger angular scales, to conduct a search for such objects. During the 2012–2013 season, the telescope was used to continuously observe a 100 deg 2 patch of sky centered atmore » R.A. 23 h30 m and decl. –55° using the polarization-sensitive SPTpol camera in two bands centered at 95 and 150 GHz. These 6000 hr of observations provided continuous monitoring for day- to month-scale millimeter-wave transient sources at the 10 mJy level. As a result, one candidate object was observed with properties broadly consistent with a GRB afterglow, but at a statistical significance too low (p = 0.01) to confirm detection.« less

Ground station hardware for the ATS-F millimeter wave experiment

NASA Technical Reports Server (NTRS)

Duffield, T. L.

1973-01-01

The results are presented of a program to design, fabricate, test, and install a primary ATS-F millimeter wave ground receiving station. Propagation parameters at millimeter waves are discussed along with the objective of the overall experiment. A general description is given of the receiving system and its function in the experiment. Typical receiver characteristics are presented which show that the experiment is entirely feasible from a link SNR standpoint. The receiving system hardware designs are discussed with separate treatment given to the propagation and the radiometer receiver designs. The modification and relocation are described of an existing 15-ft antenna to meet the ATS-F requirements. The design of a dual frequency feed subsystem and self calibration equipment is included.

Dry Valleys, Antarctica

NASA Image and Video Library

2009-11-02

The McMurdo Dry Valleys are a row of valleys west of McMurdo Sound, Antarctica. They are so named because of their extremely low humidity and lack of snow and ice cover. This image was acquired December 8, 2002 by NASA Terra spacecraft.

Comparison of phase velocities from array measurements of Rayleigh waves associated with microtremor and results calculated from borehole shear-wave velocity profiles

USGS Publications Warehouse

Liu, Hsi-Ping; Boore, David M.; Joyner, William B.; Oppenheimer, David H.; Warrick, Richard E.; Zhang, Wenbo; Hamilton, John C.; Brown, Leo T.

2000-01-01

Shear-wave velocities (VS) are widely used for earthquake ground-motion site characterization. VS data are now largely obtained using borehole methods. Drilling holes, however, is expensive. Nonintrusive surface methods are inexpensive for obtaining VS information, but not many comparisons with direct borehole measurements have been published. Because different assumptions are used in data interpretation of each surface method and public safety is involved in site characterization for engineering structures, it is important to validate the surface methods by additional comparisons with borehole measurements. We compare results obtained from a particular surface method (array measurement of surface waves associated with microtremor) with results obtained from borehole methods. Using a 10-element nested-triangular array of 100-m aperture, we measured surface-wave phase velocities at two California sites, Garner Valley near Hemet and Hollister Municipal Airport. The Garner Valley site is located at an ancient lake bed where water-saturated sediment overlies decomposed granite on top of granite bedrock. Our array was deployed at a location where seismic velocities had been determined to a depth of 500 m by borehole methods. At Hollister, where the near-surface sediment consists of clay, sand, and gravel, we determined phase velocities using an array located close to a 60-m deep borehole where downhole velocity logs already exist. Because we want to assess the measurements uncomplicated by uncertainties introduced by the inversion process, we compare our phase-velocity results with the borehole VS depth profile by calculating fundamental-mode Rayleigh-wave phase velocities from an earth model constructed from the borehole data. For wavelengths less than ~2 times of the array aperture at Garner Valley, phase-velocity results from array measurements agree with the calculated Rayleigh-wave velocities to better than 11%. Measurement errors become larger for wavelengths 2

Computer aided design of monolithic microwave and millimeter wave integrated circuits and subsystems

NASA Astrophysics Data System (ADS)

Ku, Walter H.; Gang, Guan-Wan; He, J. Q.; Ichitsubo, I.

1988-05-01

This final technical report presents results on the computer aided design of monolithic microwave and millimeter wave integrated circuits and subsystems. New results include analytical and computer aided device models of GaAs MESFETs and HEMTs or MODFETs, new synthesis techniques for monolithic feedback and distributed amplifiers and a new nonlinear CAD program for MIMIC called CADNON. This program incorporates the new MESFET and HEMT model and has been successfully applied to the design of monolithic millimeter-wave mixers.

Optically addressed ultra-wideband phased antenna array

NASA Astrophysics Data System (ADS)

Bai, Jian

Demands for high data rate and multifunctional apertures from both civilian and military users have motivated development of ultra-wideband (UWB) electrically steered phased arrays. Meanwhile, the need for large contiguous frequency is pushing operation of radio systems into the millimeter-wave (mm-wave) range. Therefore, modern radio systems require UWB performance from VHF to mm-wave. However, traditional electronic systems suffer many challenges that make achieving these requirements difficult. Several examples includes: voltage controlled oscillators (VCO) cannot provide a tunable range of several octaves, distribution of wideband local oscillator signals undergo high loss and dispersion through RF transmission lines, and antennas have very limited bandwidth or bulky sizes. Recently, RF photonics technology has drawn considerable attention because of its advantages over traditional systems, with the capability of offering extreme power efficiency, information capacity, frequency agility, and spatial beam diversity. A hybrid RF photonic communication system utilizing optical links and an RF transducer at the antenna potentially provides ultra-wideband data transmission, i.e., over 100 GHz. A successful implementation of such an optically addressed phased array requires addressing several key challenges. Photonic generation of an RF source with over a seven-octave bandwidth has been demonstrated in the last few years. However, one challenge which still remains is how to convey phased optical signals to downconversion modules and antennas. Therefore, a feed network with phase sweeping capability and low excessive phase noise needs to be developed. Another key challenge is to develop an ultra-wideband array antenna. Modern frontends require antennas to be compact, planar, and low-profile in addition to possessing broad bandwidth, conforming to stringent space, weight, cost, and power constraints. To address these issues, I will study broadband and miniaturization

Millimeter wave satellite concepts. Volume 2: Technical report

NASA Technical Reports Server (NTRS)

Hilsen, N. B.; Holland, L. D.; Wallace, R. W.; Kelly, D. L.; Thomas, R. R.; Vogler, F. H.

1979-01-01

Identification of technologies for millimeter satellite communication systems, and assessment of the relative risks of these technologies, were accomplished through subsystem modeling and link optimization for both point-to-point and broadcast applications. The results, in terms of annual cost per channel to the user from a commercial view point, are described.

Biological Effects of Millimeter-Wave Irradiation.

DTIC Science & Technology

1982-12-01

With the recent advances in millimeter-wave technology, including the availability of high - power transmitters in this band , the interaction of fields at... power was 14 mW for E- band , 10 mW for U- band ; and the frequency increment was 0.5 GHz. The mean values and the SD for the number of revertant colonies... high stability for short periods (i.e., about 30 minutes). We are now evaluating electronic means of stabilizing the klystron so that a ±1-MHz

Millimeter Continuum Observations Of Disk Solids

NASA Astrophysics Data System (ADS)

Andrews, Sean

2016-07-01

I will offer a condensed overview of some key issues in protoplanetary disk research that makes use interferometric measurements of the millimeter-wavelength continuum emitted by their solid particles. Several lines of evidence now qualitatively support theoretical models for the growth and migration of disk solids, but also advertise a quantitative tension with the traditional efficiency of that evolution. New observations of small-scale substructures in disks might both reconcile the conflict and shift our focus in the mechanics of planet formation.

Ultra-Wideband Millimeter-Wave Dielectric Characteristics of Freshly Excised Normal and Malignant Human Skin Tissues.

PubMed

Mirbeik-Sabzevari, Amir; Ashinoff, Robin; Tavassolian, Negar

2018-06-01

Millimeter waves have recently gained attention for the evaluation of skin lesions and the detection of skin tumors. Such evaluations heavily rely on the dielectric contrasts existing between normal and malignant skin tissues at millimeter-wave frequencies. However, current studies on the dielectric properties of normal and diseased skin tissues at these frequencies are limited and inconsistent. In this study, a comprehensive dielectric spectroscopy study is conducted for the first time to characterize the ultra-wideband dielectric properties of freshly excised normal and malignant skin tissues obtained from skin cancer patients having undergone Mohs micrographic surgeries at Hackensack University Medical Center. Measurements are conducted using a precision slim-form open-ended coaxial probe in conjunction with a millimeter-wave vector network analyzer over the frequency range of 0.5-50 GHz. A one-pole Cole-Cole model is fitted to the complex permittivity dataset of each sample. Statistically considerable contrasts are observed between the dielectric properties of malignant and normal skin tissues over the ultra-wideband millimeter-wave frequency range considered.

Strategies on solar observation of Atacama Large Millimeter/submillimeter Array (ALMA) band-1 receiver

NASA Astrophysics Data System (ADS)

Chiong, Chau-Ching; Chiang, Po-Han; Hwang, Yuh-Jing; Huang, Yau-De

2016-07-01

ALMA covering 35-950 GHz is the largest existing telescope array in the world. Among the 10 receiver bands, Band-1, which covers 35-50 GHz, is the lowest. Due to its small dimension and its time-variant frequency-dependent gain characteristics, current solar filter located above the cryostat cannot be applied to Band-1 for solar observation. Here we thus adopt new strategies to fulfill the goals. Thanks to the flexible dc biasing scheme of the HEMT-based amplifier in Band-1 front-end, bias adjustment of the cryogenic low noise amplifier is investigated to accomplish solar observation without using solar filter. Large power handling range can be achieved by the de-tuning bias technique with little degradation in system performance.

Millimeter-Wave Propagation and Remote Sensing of the Atmosphere,

DTIC Science & Technology

1983-12-01

tool to probe lower atmospheric structure. The principal applications of millimeter waves have been in the areas of communications, radar, and remote ... sensing . The availability of large bandwidths makes this region of the spectrum particularly attractive for high data rate communications. Because

Ground-water conditions in southern Utah Valley and Goshen Valley, Utah

USGS Publications Warehouse

Cordova, R.M.

1970-01-01

The investigation of ground-water conditions in southern Utah Valley and Goshen Valley, Utah, was made by the U. S. Geological Survey as part of a cooperative program with the Utah Department of Natural Resources, Division of Water Rights, to investigate the water resources of the State. The purposes of the investigation were to (1) determine the occurrence, recharge, discharge, movement, storage, chemical quality, and availability of ground water; (2) appraise the effects of increased withdrawal of water from wells; and (3) evaluate the effect of the Central Utah Project on the ground-water reservoir and the water supply of Utah Lake.This report presents a description of the aquifer system in the two valleys, a detailed description of the ground-water resources, and conclusions about potential development and its effect on the hydrologic conditions in the valleys. Two supplementary reports are products of the investigation. A basic-data release (Cordova, 1969) contains most of the basic data collected for the investigation, including well characteristics, drillers' logs, water levels, pumpage from wells, chemical analyses of ground and surface waters, and discharge of selected springs, drains, and streams. An interpretive report (Cordova and Mower, 1967) contains the results of a large-scale aquifer test in southern Utah Valley.

Millimeter-wave interconnects for microwave-frequency quantum machines

NASA Astrophysics Data System (ADS)

Pechal, Marek; Safavi-Naeini, Amir H.

2017-10-01

Superconducting microwave circuits form a versatile platform for storing and manipulating quantum information. A major challenge to further scalability is to find approaches for connecting these systems over long distances and at high rates. One approach is to convert the quantum state of a microwave circuit to optical photons that can be transmitted over kilometers at room temperature with little loss. Many proposals for electro-optic conversion between microwave and optics use optical driving of a weak three-wave mixing nonlinearity to convert the frequency of an excitation. Residual absorption of this optical pump leads to heating, which is problematic at cryogenic temperatures. Here we propose an alternative approach where a nonlinear superconducting circuit is driven to interconvert between microwave-frequency (7 ×109 Hz) and millimeter-wave-frequency photons (3 ×1011 Hz). To understand the potential for quantum state conversion between microwave and millimeter-wave photons, we consider the driven four-wave mixing quantum dynamics of nonlinear circuits. In contrast to the linear dynamics of the driven three-wave mixing converters, the proposed four-wave mixing converter has nonlinear decoherence channels that lead to a more complex parameter space of couplings and pump powers that we map out. We consider physical realizations of such converter circuits by deriving theoretically the upper bound on the maximum obtainable nonlinear coupling between any two modes in a lossless circuit, and synthesizing an optimal circuit based on realistic materials that saturates this bound. Our proposed circuit dissipates less than 10-9 times the energy of current electro-optic converters per qubit. Finally, we outline the quantum link budget for optical, microwave, and millimeter-wave connections, showing that our approach is viable for realizing interconnected quantum processors for intracity or quantum data center environments.

Microwave, Millimeter, Submillimeter, and Far Infrared Spectral Databases

NASA Technical Reports Server (NTRS)

Pearson, J. C.; Pickett, H. M.; Drouin, B. J.; Chen, P.; Cohen, E. A.

2002-01-01

The spectrum of most known astrophysical molecules is derived from transitions between a few hundred to a few hundred thousand energy levels populated at room temperature. In the microwave and millimeter wave regions. spectroscopy is almost always performed with traditional microwave techniques. In the submillimeter and far infrared microwave technique becomes progressively more technologically challenging and infrared techniques become more widely employed as the wavelength gets shorter. Infrared techniques are typically one to two orders of magnitude less precise but they do generate all the strong features in the spectrum. With microwave technique, it is generally impossible and rarely necessary to measure every single transition of a molecular species, so careful fitting of quantum mechanical Hamiltonians to the transitions measured are required to produce the complete spectral picture of the molecule required by astronomers. The fitting process produces the most precise data possible and is required in the interpret heterodyne observations. The drawback of traditional microwave technique is that precise knowledge of the band origins of low lying excited states is rarely gained. The fitting of data interpolates well for the range of quantum numbers where there is laboratory data, but extrapolation is almost never precise. The majority of high resolution spectroscopic data is millimeter or longer in wavelength and a very limited number of molecules have ever been studied with microwave techniques at wavelengths shorter than 0.3 millimeters. The situation with infrared technique is similarly dire in the submillimeter and far infrared because the black body sources used are competing with a very significant thermal background making the signal to noise poor. Regardless of the technique used the data must be archived in a way useful for the interpretation of observations.

Solvothermal transformation of a calcium oleate precursor into large-sized highly ordered arrays of ultralong hydroxyapatite microtubes.

PubMed

Lu, Bing-Qiang; Zhu, Ying-Jie; Chen, Feng; Qi, Chao; Zhao, Xin-Yu; Zhao, Jing

2014-06-02

Hydroxyapatite (HAP), a well-known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge. In this work, inspired by the ordered structure of tooth enamel, we have successfully synthesized three-dimensional bulk materials with large sizes (millimeter scale) that are made of highly ordered arrays of ultralong HAP microtubes (HOAUHMs) by solvothermal transformation of calcium oleate precursor. The core-shell-structured oblate sphere consists of a core that is composed of HAP nanorods and a shell that consists of highly ordered HAP microtube arrays. The prepared HOAUHMs are large: 6.0 mm in diameter and up to 1.4 mm in thickness. With increasing solvothermal reaction time, the HOAUHMs grow larger; the microtubes become more uniform and more ordered. This work provides a new synthetic method for synthesizing highly ordered arrays of uniform HAP ultralong microtubes that are promising for biomedical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-Resolution Millimeter-VLBI Imaging of the super-massive black hole candidate at the Galactic center - Sgr A*

NASA Astrophysics Data System (ADS)

Shen, Zqs

Sagittarius A* (Sgr A*), the extremely compact radio source at the Galactic center (GC), is the best candidate for the single super-massive black hole (SMBH). The accurate measurements of its mass (as a gravitational source) and size (as a radiative source) are of great importance in testing its SMBH hypothesis. Great progress has been made on determining its central dark mass of 3.7 million solar masses. Here, we will present the highest resolution VLBI imaging observations of Sgr A* made at both 7.0 and 3.5 millimeters with the Very Long Baseline Array (VLBA) plus the Green Bank Telescope (GBT) and the VLBA, respectively. Both the imaging and the model-fitting with the closure amplitudes show a consistent East-West elongated elliptical Gaussian emission. The inferred possible intrinsic emitting region is less than 1 AU at the distance of 8 kpc to GC.

Analysis of Mining-induced Valley Closure Movements

NASA Astrophysics Data System (ADS)

Zhang, C.; Mitra, R.; Oh, J.; Hebblewhite, B.

2016-05-01

Valley closure movements have been observed for decades in Australia and overseas when underground mining occurred beneath or in close proximity to valleys and other forms of irregular topographies. Valley closure is defined as the inward movements of the valley sides towards the valley centreline. Due to the complexity of the local geology and the interplay between several geological, topographical and mining factors, the underlying mechanisms that actually cause this behaviour are not completely understood. A comprehensive programme of numerical modelling investigations has been carried out to further evaluate and quantify the influence of a number of these mining and geological factors and their inter-relationships. The factors investigated in this paper include longwall positional factors, horizontal stress, panel width, depth of cover and geological structures around the valley. It is found that mining in a series passing beneath the valley dramatically increases valley closure, and mining parallel to valley induces much more closure than other mining orientations. The redistribution of horizontal stress and influence of mining activity have also been recognised as important factors promoting valley closure, and the effect of geological structure around the valley is found to be relatively small. This paper provides further insight into both the valley closure mechanisms and how these mechanisms should be considered in valley closure prediction models.

The Inter-Valley Soil Comparative Survey: the ecology of Dry Valley edaphic microbial communities

PubMed Central

Lee, Charles K; Barbier, Béatrice A; Bottos, Eric M; McDonald, Ian R; Cary, Stephen Craig

2012-01-01

Recent applications of molecular genetics to edaphic microbial communities of the McMurdo Dry Valleys and elsewhere have rejected a long-held belief that Antarctic soils contain extremely limited microbial diversity. The Inter-Valley Soil Comparative Survey aims to elucidate the factors shaping these unique microbial communities and their biogeography by integrating molecular genetic approaches with biogeochemical analyses. Although the microbial communities of Dry Valley soils may be complex, there is little doubt that the ecosystem's food web is relatively simple, and evidence suggests that physicochemical conditions may have the dominant role in shaping microbial communities. To examine this hypothesis, bacterial communities from representative soil samples collected in four geographically disparate Dry Valleys were analyzed using molecular genetic tools, including pyrosequencing of 16S rRNA gene PCR amplicons. Results show that the four communities are structurally and phylogenetically distinct, and possess significantly different levels of diversity. Strikingly, only 2 of 214 phylotypes were found in all four valleys, challenging a widespread assumption that the microbiota of the Dry Valleys is composed of a few cosmopolitan species. Analysis of soil geochemical properties indicated that salt content, alongside altitude and Cu2+, was significantly correlated with differences in microbial communities. Our results indicate that the microbial ecology of Dry Valley soils is highly localized and that physicochemical factors potentially have major roles in shaping the microbiology of ice-free areas of Antarctica. These findings hint at links between Dry Valley glacial geomorphology and microbial ecology, and raise previously unrecognized issues related to environmental management of this unique ecosystem. PMID:22170424

27 CFR 9.132 - Rogue Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rogue Valley. 9.132... Rogue Valley. (a) Name. The name of the viticultural area described in this section is “Rouge Valley.” (b) Approved map. The appropriate map for determining the boundaries of the Rogue Valley viticultural...

Micro-Ring Structures Stabilize Microdroplets to Enable Long Term Spheroid Culture in 384 Hanging Drop Array Plates

PubMed Central

Hsiao, Amy Y.; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J.; Takayama, Shuichi

2012-01-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis. PMID:22057945

Micro-ring structures stabilize microdroplets to enable long term spheroid culture in 384 hanging drop array plates.

PubMed

Hsiao, Amy Y; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J; Takayama, Shuichi

2012-04-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis.

HIGH-PRECISION ASTROMETRIC MILLIMETER VERY LONG BASELINE INTERFEROMETRY USING A NEW METHOD FOR ATMOSPHERIC CALIBRATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rioja, M.; Dodson, R., E-mail: maria.rioja@icrar.org

2011-04-15

We describe a new method which achieves high-precision very long baseline interferometry (VLBI) astrometry in observations at millimeter (mm) wavelengths. It combines fast frequency-switching observations, to correct for the dominant non-dispersive tropospheric fluctuations, with slow source-switching observations, for the remaining ionospheric dispersive terms. We call this method source-frequency phase referencing. Provided that the switching cycles match the properties of the propagation media, one can recover the source astrometry. We present an analytic description of the two-step calibration strategy, along with an error analysis to characterize its performance. Also, we provide observational demonstrations of a successful application with observations using themore » Very Long Baseline Array at 86 GHz of the pairs of sources 3C274 and 3C273 and 1308+326 and 1308+328 under various conditions. We conclude that this method is widely applicable to mm-VLBI observations of many target sources, and unique in providing bona fide astrometrically registered images and high-precision relative astrometric measurements in mm-VLBI using existing and newly built instruments, including space VLBI.« less

Geophysical Surveys of the Hydrologic Basin Underlying Yosemite Valley, California.

NASA Astrophysics Data System (ADS)

Maher, E. L.; Shaw, K. A.; Carey, C.; Dunn, M. E.; Whitman, S.; Bourdeau, J.; Eckert, E.; Louie, J. N.; Stock, G. M.

2017-12-01

UNR students in an Applied Geophysics course conducted geophysical investigations in Yosemite Valley during the months of March and August 2017. The goal of the study is to understand better the depth to bedrock, the geometry of the bedrock basin, and the properties of stratigraphy- below the valley floor. Gutenberg and others published the only prior geophysical investigation in 1956, to constrain the depth to bedrock. We employed gravity, resistivity, and refraction microtremor(ReMi) methods to investigate the interface between valley fill and bedrock, as well as shallow contrasts. Resistivity and ReMi arrays along three north-south transects investigated the top 50-60m of the basin fill. Gravity results constrained by shallow measurements suggest a maximum depth of 1000 m to bedrock. ReMi and resistivity techniques identified shallow contrasts in shear velocity and electrical resistivity that yielded information about the location of the unconfined water table, the thickness of the soil zone, and spatial variation in shallow sediment composition. The upper several meters of sediment commonly showed shear velocities below 200 m/s, while biomass-rich areas and sandy river banks could be below 150 m/s. Vs30 values consistently increased towards the edge of the basin. The general pattern for resistivity profiles was a zone of relatively high resistivity, >100 ohm-m, in the top 4 meters, followed by one or more layers with decreased resistivity. According to gravity measurements, assuming either -0.5 g/cc or -0.7 g/cc density contrast between bedrock and basin sediments, a maximum depth to bedrock is found south of El Capitan at respectively, 1145 ± 215 m or 818 ± 150 m. Longitudinal basin geometry coincides with the basin depth geometry discussed by Gutenberg in 1956. Their results describe a "double camel" shape where the deepest points are near El Capitan and the Ahwahnee Hotel and is shallowest near Yosemite Falls, in a wider part of the valley. An August Deep

Calving of Talyor Glacier, Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Carmichael, J. D.; Pettit, E. C.; Creager, K. C.; Hallet, B.

2007-12-01

Calving of tide-water glaciers has received considerable attention, with seismic arrays in Alaska, Greenland, and Antarctica devoted to their observation. In these environments, ice cliffs are directly coupled to oceanic temperatures. The land-based polar glaciers of the McMurdo Dry Valleys in Antarctica represent a simpler environment unaffected directly by water contact where other factors can be isolated. In particular, summer calving events of Taylor Glacier are observed to consist of precursory activity including crack growth, cliff overhang, and active seismicity at least 1 hour before collapse. We propose that collapse occurs only after a stress threshold has been crossed, evident from 'pre-calving' of ice from the cliff base 1-3 days prior to the major event. We provide photographic, seismic, and temperature data to illustrate the thermal and stress landscape for land-based calving of polar glaciers.

Twenty and thirty GHz millimeter wave experiments with the ATS-6 satellite

NASA Technical Reports Server (NTRS)

Ippolito, L. J. (Compiler)

1975-01-01

The ATS-6 millimeter wave experiment, provided the first direct measurements of 20 and 30 GHz earth-space links from an orbiting satellite. Studies at eleven locations in the continental United States were directed at an evaluation of rain attenuation effects, scintillations, depolarization, site diversity, coherence bandwidth, and analog and digital communications techniques. In addition to direct measurements on the 20 and 30 GHz links, methods of attenuation prediction with radars, rain gages, and radiometers were developed and compared with the directly measured attenuation. Initial data results of the ATS-6 millimeter wave experiment from the major participating organizations are presented.

Performance Investigation of Millimeter Wave Generation Reliant on Stimulated Brillouin Scattering

NASA Astrophysics Data System (ADS)

Tickoo, Sheetal; Gupta, Amit

2018-04-01

In this work, photonic method of generating the millimeter waves has been done based on Brillouin scattering effect in optical fiber. Here different approaches are proposed to get maximum frequency shift in mm-wave region using only pumps, radio signals with Mach-Zehnder modulator. Moreover for generated signal validation, signals modulated and send to both wired and wireless medium in optical domain. It is observed that maximum shift of 300 GHz is realized using 60 GHz input sine wave. Basically a frequency doubler is proposed which double shift of input frequency and provide better SNR. For the future generation network system, the generation of millimeter waves makes them well reliable for the transmission of the data.

A Sub-millimeter, Inductively Powered Neural Stimulator

PubMed Central

Freeman, Daniel K.; O'Brien, Jonathan M.; Kumar, Parshant; Daniels, Brian; Irion, Reed A.; Shraytah, Louis; Ingersoll, Brett K.; Magyar, Andrew P.; Czarnecki, Andrew; Wheeler, Jesse; Coppeta, Jonathan R.; Abban, Michael P.; Gatzke, Ronald; Fried, Shelley I.; Lee, Seung Woo; Duwel, Amy E.; Bernstein, Jonathan J.; Widge, Alik S.; Hernandez-Reynoso, Ana; Kanneganti, Aswini; Romero-Ortega, Mario I.; Cogan, Stuart F.

2017-01-01

Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless stimulators on the sub-millimeter scale (<1 mm3) is challenging. As device size shrinks, it becomes difficult to deliver sufficient wireless power to operate the device. Here, we present a sub-millimeter, inductively powered neural stimulator consisting only of a coil to receive power, a capacitor to tune the resonant frequency of the receiver, and a diode to rectify the radio-frequency signal to produce neural excitation. By replacing any complex receiver circuitry with a simple rectifier, we have reduced the required voltage levels that are needed to operate the device from 0.5 to 1 V (e.g., for CMOS) to ~0.25–0.5 V. This reduced voltage allows the use of smaller receive antennas for power, resulting in a device volume of 0.3–0.5 mm3. The device was encapsulated in epoxy, and successfully passed accelerated lifetime tests in 80°C saline for 2 weeks. We demonstrate a basic proof-of-concept using stimulation with tens of microamps of current delivered to the sciatic nerve in rat to produce a motor response. PMID:29230164

Hydrogeologic framework and estimates of groundwater storage for the Hualapai Valley, Detrital Valley, and Sacramento Valley basins, Mohave County, Arizona

USGS Publications Warehouse

Truini, Margot; Beard, L. Sue; Kennedy, Jeffrey; Anning, Dave W.

2013-01-01

We have investigated the hydrogeology of the Hualapai Valley, Detrital Valley, and Sacramento Valley basins of Mohave County in northwestern Arizona to develop a better understanding of groundwater storage within the basin fill aquifers. In our investigation we used geologic maps, well-log data, and geophysical surveys to delineate the sedimentary textures and lithology of the basin fill. We used gravity data to construct a basin geometry model that defines smaller subbasins within the larger basins, and airborne transient-electromagnetic modeled results along with well-log lithology data to infer the subsurface distribution of basin fill within the subbasins. Hydrogeologic units (HGUs) are delineated within the subbasins on the basis of the inferred lithology of saturated basin fill. We used the extent and size of HGUs to estimate groundwater storage to depths of 400 meters (m) below land surface (bls). The basin geometry model for the Hualapai Valley basin consists of three subbasins: the Kingman, Hualapai, and southern Gregg subbasins. In the Kingman subbasin, which is estimated to be 1,200 m deep, saturated basin fill consists of a mixture of fine- to coarse-grained sedimentary deposits. The Hualapai subbasin, which is the largest of the subbasins, contains a thick halite body from about 400 m to about 4,300 m bls. Saturated basin fill overlying the salt body consists predominately of fine-grained older playa deposits. In the southern Gregg subbasin, which is estimated to be 1,400 m deep, saturated basin fill is interpreted to consist primarily of fine- to coarse-grained sedimentary deposits. Groundwater storage to 400 m bls in the Hualapai Valley basin is estimated to be 14.1 cubic kilometers (km3). The basin geometry model for the Detrital Valley basin consists of three subbasins: northern Detrital, central Detrital, and southern Detrital subbasins. The northern and central Detrital subbasins are characterized by a predominance of playa evaporite and fine

Fretted Terrain Valleys

NASA Technical Reports Server (NTRS)

2004-01-01

30 October 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows shallow tributary valleys in the Ismenius Lacus fretted terrain region of northern Arabia Terra. These valleys exhibit a variety of typical fretted terrain valley wall and floor textures, including a lineated, pitted material somewhat reminiscent of the surface of a brain. Origins for these features are still being debated within the Mars science community; there are no clear analogs to these landforms on Earth. This image is located near 39.9oN, 332.1oW. The picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

A First Comparison of Millimeter Continuum and Mg ii Ultraviolet Line Emission from the Solar Chromosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bastian, T. S.; Chintzoglou, G.; De Pontieu, B.

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph ( IRIS ). Both millimeter/submillimeter- λ continuum emission and ultraviolet (UV) line emission originate from the solar chromosphere and both have the potential to serve as powerful and complementary diagnostics of physical conditions in this enigmatic region of the solar atmosphere. The observations were made of a solar active region on 2015 December 18 as part of the ALMA science verification effort. A map of the Sun’s continuum emission was obtained by ALMA at a wavelength of 1.25 mm (239more » GHz). A contemporaneous map was obtained by IRIS in the Mg ii h doublet line at 2803.5 Å. While a clear correlation between the 1.25 mm brightness temperature T{sub B} and the Mg ii h line radiation temperature T {sub rad} is observed, the slope is <1, perhaps as a result of the fact that these diagnostics are sensitive to different parts of the chromosphere and that the Mg ii h line source function includes a scattering component. There is a significant difference (35%) between the mean T{sub B} (1.25 mm) and mean T {sub rad} (Mg ii). Partitioning the maps into “sunspot,” “quiet areas,” and “plage regions” we find the relation between the IRIS Mg ii h line T {sub rad} and the ALMA T {sub B} region-dependent. We suggest this may be the result of regional dependences of the formation heights of the IRIS and ALMA diagnostics and/or the increased degree of coupling between the UV source function and the local gas temperature in the hotter, denser gas in plage regions.« less

Wave-Coupled Millimeter-Wave Electro-Optic Techniques

DTIC Science & Technology

2001-03-01

This report details results on two antenna-coupled millimeter-wave electro - optic modulators, the slot-vee antenna-coupled modulator and a 94 GHz...study of the effects of velocity mismatch on linearized electro - optic modulators was made and the results published. A key result was that directional...drift in electro - optic modulators was made and protons were determined to be the cause. Several inventions were made to reduce or eliminate proton-caused bias drift.

Millimeter-wave molecular line observations of the Tornado nebula

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakai, D.; Oka, T.; Tanaka, K.

We report the results of millimeter-wave molecular line observations of the Tornado Nebula (G357.7-0.1), which is a bright radio source behind the Galactic center region. A 15' × 15' area was mapped in the J = 1-0 lines of CO, {sup 13}CO, and HCO{sup +} with the Nobeyama Radio Observatory 45 m telescope. The Very Large Array archival data of OH at 1720 MHz were also reanalyzed. We found two molecular clouds with separate velocities, V{sub LSR} = –14 km s{sup –1} and +5 km s{sup –1}. These clouds show rough spatial anti-correlation. Both clouds are associated with OH 1720more » MHz emissions in the area overlapping with the Tornado Nebula. The spatial and velocity coincidence indicates violent interaction between the clouds and the Tornado Nebula. Modestly excited gas prefers the position of the Tornado 'head' in the –14 km s{sup –1} cloud, also suggesting the interaction. Virial analysis shows that the +5 km s{sup –1} cloud is more tightly bound by self-gravity than the –14 km s{sup –1} cloud. We propose a formation scenario for the Tornado Nebula; the +5 km s{sup –1} cloud collided into the –14 km s{sup –1} cloud, generating a high-density layer behind the shock front, which activates a putative compact object by Bondi-Hoyle-Lyttleton accretion to eject a pair of bipolar jets.« less

Geologic history of the Yosemite Valley

USGS Publications Warehouse

Matthes, Francois E.

1930-01-01

Projection of the longitudinal profiles of these hanging valleys forward to the axis of the Merced Canyon shows that they are closely accordant in height. Their profiles indicate a series of points on a former profile of the Merced with respect to which the side streams had graded their courses prior to the last uplift. This old profile can be extended upward into the glaciated part of the Merced Canyon above El Portal and even into the profoundly glaciated Yosemite Valley, accordant points being furnished by a number of hanging side valleys (due allowance being made for glacial erosion suffered by those valleys). However, not all the hanging valleys of the Yosemite region are accordant with this set. Several of them, including the upland valley of Yosemite Creek, constitute a separate set indicating another old profile of the Merced at a level 600 to 1,000 feet higher than the first. Others, including the hanging gulch of lower Bridalveil Creek, point to an old profile of the Merced about 1,200 feet lower than the first. There are thus three distinct sets of hanging valleys produced in three cycles of stream erosion. The valleys of the upper set, like those of the middle set, were left hanging as a result of rapid trenching by the Merced induced by an uplift of the range, there having been two such uplifts. Only the valleys of the lower set hang because of glacial deepening and widening of the Yosemite Valley, the cycle in which they were cut having been interrupted by the advent of the Pleistocene glaciers. They consequently indicate the preglacial depth of the Yosemite Valley. That depth, measured from the brow of El Capitan, was about 2,400 feet; measured from the rim at Glacier Point it was about 2,000 feet.

Observations of stimulated Raman scattering and laser-induced breakdown in millimeter-sized droplets

NASA Technical Reports Server (NTRS)

Biswas, A.; Pinnick, R. G.; Xie, J.-G.; Ruekgauer, T. E.; Armstrong, R. L.

1992-01-01

We report the first observations, to our knowledge, of nonlinear optical effects in large (millimeter-sized) droplets. Stimulated Raman scattering (SRS) and laser-induced breakdown (LIB) are simultaneously observed in acoustically levitated millimeter-sized glycerol droplets irradiated by either a frequency-doubled (532-nm) or a frequency-tripled (355-nm) Nd:YAG laser. The two processes, which occur above a nearby coincident irradiation threshold, are conjectured to arise from a common initiation mechanism: self-focusing. LIB generates vapor bubbles within the droplet, resulting in the quenching of SRS emission.

Joint Analysis of the Full AzTEC Sub-Millimeter Galaxy Data Set

NASA Astrophysics Data System (ADS)

Wilson, Grant; Ade, P.; Aretxaga, I.; Austermann, J.; Bock, J.; Hughes, D.; Kang, Y.; Kim, S.; Lowenthal, J.; Mauskopf, P.; Perera, T.; Scott, K.; Yun, M.

2006-12-01

Using the new AzTEC millimeter-wave camera on the James Clerk Maxwell Telescope (JCMT) in winter 2005/06, we conducted several surveys of the submm galaxy (SMG) population. The AzTEC 1.1 millimeter surveys include both blank-fields (no significant bias or foreground contamination) and regions of known over-densities, and are both large (100-1000 sq. arcmin.) and sensitive ( 1 mJy rms). The unique power of the AzTEC data set lies not only in the size and depth of the individual fields, but in the combined surveyed area that totals over 1 square degree. Hundreds of new sub-millimeter sources have been detected. A joint analysis of all AzTEC surveys will provide important new constraints on many characteristics of the SMG population, including number counts, clustering, and variance. In particular, the large area of the full AzTEC data set provides the first significant measurement of the brightest and most rare of the SMG population. Herein we present the initial combined results and explore the future potential of a complete joint analysis of the full AzTEC SMG data set.

76 FR 22746 - Conecuh Valley Railway, LLC-Acquisition and Operation Exemption-Conecuh Valley Railroad Co., Inc.

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-22

... Railway, LLC--Acquisition and Operation Exemption--Conecuh Valley Railroad Co., Inc. Conecuh Valley Railway, LLC (CVR), a noncarrier, has filed a verified notice of exemption under 49 CFR 1150.31 to acquire from Conecuh Valley Railroad Co., Inc. (COEH), and to operate [[Page 22747

Electromagnetic Considerations for Planar Bolometer Arrays in the Single Mode Limit

NASA Technical Reports Server (NTRS)

Wollack, Edward J.; Chuss, David T.; Moseley, Samuel

2006-01-01

Filled arrays of planar bolometers are finding astronomical applications at wavelengths as long as several millimeters. In an effort to keep focal planes to a reasonable size while maintaining large numbers of detectors, a common strategy is to push these arrays to operate close to or at the single mode limit. Doing so introduces several new challenges that are not experienced in the multi-mode case of far-infrared detectors having similar pixel sizes. First, diffractive effects of the pixels themselves are no longer insignificant and will ultimately contribute to the resolution limit of the optical system in which they reside. We use the method of Withlngton et al. (2003) to model the polarized diffraction in this limit. Second, it is necessary to re-examine the coupling between the radiation and the absorbing element that is thermally connected to the bolometers. The small f-numbers that are often employed to make use of large focal planes makes backshort construction problematic. We introduce a new strategy to increase detector efficiency that uses an antireflective layer on the front side of the detector array. In addition, typical methods for stray light control that rely on multiple reflections in a lossy medium fail due to physical size constraints. For this application, we find that resonant absorbers are a more effective strategy that can be implemented in the space available.

MAPPING THE RELEASE OF VOLATILES IN THE INNER COMAE OF COMETS C/2012 F6 (LEMMON) AND C/2012 S1 (ISON) USING THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cordiner, M. A.; Milam, S. N.; Mumma, M. J.

2014-09-01

Results are presented from the first cometary observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), including measurements of the spatially resolved distributions of HCN, HNC, H{sub 2}CO, and dust within the comae of two comets: C/2012 F6 (Lemmon) and C/2012 S1 (ISON), observed at heliocentric distances of 1.5 AU and 0.54 AU, respectively. These observations (with angular resolution ≈0.''5), reveal an unprecedented level of detail in the distributions of these fundamental cometary molecules, and demonstrate the power of ALMA for quantitative measurements of the distributions of molecules and dust in the inner comae of typical bright comets. In both comets, HCN ismore » found to originate from (or within a few hundred kilometers of) the nucleus, with a spatial distribution largely consistent with spherically symmetric, uniform outflow. By contrast, the HNC distributions are clumpy and asymmetrical, with peaks at cometocentric radii ∼500-1000 km, consistent with release of HNC in collimated outflow(s). Compared to HCN, the H{sub 2}CO distribution in comet Lemmon is very extended. The interferometric visibility amplitudes are consistent with coma production of H{sub 2}CO and HNC from unidentified precursor material(s) in both comets. Adopting a Haser model, the H{sub 2}CO parent scale length is found to be a few thousand kilometers in Lemmon and only a few hundred kilometers in ISON, consistent with the destruction of the precursor by photolysis or thermal degradation at a rate that scales in proportion to the solar radiation flux.« less

Grizzly Valley fault system, Sierra Valley, CA

USGS Publications Warehouse

Gold, Ryan; Stephenson, William; Odum, Jack; Briggs, Rich; Crone, Anthony; Angster, Steve

2012-01-01

The Grizzly Valley fault system (GVFS) strikes northwestward across Sierra Valley, California and is part of a network of active, dextral strike-slip faults in the northern Walker Lane (Figure 1). To investigate Quaternary motion across the GVFS, we analyzed high-resolution (0.25 m) airborne LiDAR data (Figure 2) in combination with six, high-resolution, P-wave, seismic-reflection profiles [Gold and others, 2012]. The 0.5- to 2.0-km-long seismic-reflection profiles were sited orthogonal to suspected tectonic lineaments identified from previous mapping and our analysis of airborne LiDAR data. To image the upper 400–700 m of subsurface stratigraphy of Sierra Valley (Figure 3), we used a 230-kg accelerated weight drop source. Geophone spacing ranged from 2 to 5 m and shots were co-located with the geophones. The profiles reveal a highly reflective, deformed basal marker that we interpret to be the top of Tertiary volcanic rocks, overlain by a 120- to 300-m-thick suite of subhorizontal reflectors we interpret as Plio-Pleistocene lacustrine deposits. Three profiles image the principle active trace of the GVFS, which is a steeply dipping fault zone that offsets the volcanic rocks and the basin fill (Figures 4 & 5).

Passive millimeter-wave imaging for concealed article detection

NASA Astrophysics Data System (ADS)

Lovberg, John A.; Galliano, Joseph A., Jr.; Clark, Stuart E.

1997-02-01

Passive-millimeter-wave imaging (PMI) provides a powerful sensing tool for law enforcement, allowing an unobtrusive means for detecting concealed weapons, explosives, or contraband on persons or in baggage. Natural thermal emissions at millimeter wavelengths from bodies, guns, explosives, and other articles pass easily through clothing or other concealment materials, where they can be detected and converted into conventional 2-dimensional images. A new implementation of PMI has demonstrated a large-area, near- real-time staring capability for personnel inspection at standoff ranges of greater than 10 meters. In this form, PMI does not require operator cuing based on subjective 'profiles' of suspicious appearance or behaviors, which may otherwise be construed as violations of civil rights. To the contrary, PMI detects and images heat generated by any object with no predisposition as to its nature or function (e.g. race or gender of humans). As a totally passive imaging tool, it generates no radio-frequency or other radiation which might raise public health concerns. Specifics of the new PMI architecture are presented along with a host of imaging data representing the current state- of-the-art.

Silicon micromachined waveguides for millimeter and submillimeter wavelengths

NASA Technical Reports Server (NTRS)

Yap, Markus; Tai, Yu-Chong; Mcgrath, William R.; Walker, Christopher

1992-01-01

The majority of radio receivers, transmitters, and components operating at millimeter and submillimeter wavelengths utilize rectangular waveguides in some form. However, conventional machining techniques for waveguides operating above a few hundred GHz are complicated and costly. This paper reports on the development of silicon micromachining techniques to create silicon-based waveguide circuits which can operate at millimeter and submillimeter wavelengths. As a first step, rectangular WR-10 waveguide structures have been fabricated from (110) silicon wafers using micromachining techniques. The waveguide is split along the broad wall. Each half is formed by first etching a channel completely through a wafer. Potassium hydroxide is used to etch smooth mirror-like vertical walls and LPCVD silicon nitride is used as a masking layer. This wafer is then bonded to another flat wafer using a polyimide bonding technique and diced into the U-shaped half wavelengths. Finally, a gold layer is applied to the waveguide walls. Insertion loss measurements show losses comparable to those of standard metal waveguides. It is suggested that active devices and planar circuits can be integrated with the waveguides, solving the traditional mounting problems. Potential applications in terahertz instrumentation technology are further discussed.

Topological Valley Currents in Gapped Dirac Materials

NASA Astrophysics Data System (ADS)

Lensky, Yuri D.; Song, Justin C. W.; Samutpraphoot, Polnop; Levitov, Leonid S.

2015-06-01

Gapped 2D Dirac materials, in which inversion symmetry is broken by a gap-opening perturbation, feature a unique valley transport regime. Topological valley currents in such materials are dominated by bulk currents produced by electronic states just beneath the gap rather than by edge modes. The system ground state hosts dissipationless persistent valley currents existing even when topologically protected edge modes are absent. Valley currents induced by an external bias are characterized by a quantized half-integer valley Hall conductivity. The undergap currents dominate magnetization and the charge Hall effect in a light-induced valley-polarized state.

Field Surveys, IOC Valleys. Volume III, Part II. Cultural Resources Survey, Pine and Wah Wah Valleys, Utah.

DTIC Science & Technology

1981-08-01

valleys are typical of the Basin and Range Province, characterized by parallel, north-south trending mountain ranges, separated by hydrologically closed... basins . Pine and Wah Wah valleys each have hardpan-playas in their lowest areas. State Highway 21 runs roughly northwest-southeast through both val...have been important for prehis- toric and historic use of the area. Pine Valley: Pine and Wah Wah valleys are closed alluvial basins . The central part

Influence of fracture anisotropy on ground water ages and chemistry, Valley and Ridge province, Pennsylvania

USGS Publications Warehouse

Burton, W.C.; Plummer, Niel; Busenberg, E.; Lindsey, B.D.; Gburek, W.J.

2002-01-01

Model ground water ages based on chlorofluorocarbons (CFCs) and tritium/helium-3 (3H/3He) data were obtained from two arrays of nested piezometers located on the north limb of an anticline in fractured sedimentary rocks in the Valley and Ridge geologic province of Pennsylvania. The fracture geometry of the gently east plunging fold is very regular and consists predominately of south dipping to subhorizontal to north dipping bedding-plane parting and east striking, steeply dipping axial-plane spaced cleavage. In the area of the piezometer arrays, which trend north-south on the north limb of the fold, north dipping bedding-plane parting is a more dominant fracture set than is steeply south dipping axial-plane cleavage. The dating of ground water from the piezometer arrays reveals that ground water traveling along paths parallel to the dip direction of bedding-plane parting has younger 3H/3He and CFC model ages, or a greater component of young water, than does ground water traveling along paths opposite to the dip direction. In predominantly unmixed samples there is a strong positive correlation between age of the young fraction of water and dissolved sodium concentration. The travel times inferred from the model ages are significantly longer than those previously calculated by a ground water flow model, which assumed isotropically fractured layers parallel to topography. A revised model factors in the directional anisotropy to produce longer travel times. Ground water travel times in the watershed therefore appear to be more influenced by anisotropic fracture geometry than previously realized. This could have significant implications for ground water models in other areas underlain by similarly tilted or folded sedimentary rock, such as elsewhere in the Valley and Ridge or the early Mesozoic basins.

Investigation of Passive Atmospheric Sounding Using Millimeter- and Submillimeter- Wavelength Channels

NASA Technical Reports Server (NTRS)

Gasiewski, Albin J.

1996-01-01

This report summarizes progress made during the period from July 1, 1994 through June 30, 1996 on the development of satellite-based observational techniques for high resolution imaging of precipitation and sounding of atmospheric ice and water vapor using passive microwave radiometers in the millimeter (MMW)- and submillimeter (SMMW)-wavelength. This is being achieved by radiative transfer modeling a millimeter and submillimeter wave frequencies and by the development and operation of an airborne millimeter wave imaging radiometer (MIR). The MIR has been used in both airborne and ground-based experiments. Its primary application is to provide calibrated radiometric imagery to verify MMW and SMMW radiative transfer models in clear air, cloud, and precipitation and to develop retrieval techniques using MMW and SMMW channels. The MIR imagery over convective storm cells has been used to illustrate the potentially useful cloud and water vapor sensing and storm-cell mapping capabilities of SMMW channels. The radiometric data has also been used to analyze radiative transfer model discrepancies caused by water vapor errors in radiosondes. The MMW and SMMW channels can be used to extend the altitude that water vapor sounding can be performed up into the lower stratosphere. Together, the use of both SMMW and MMW channels are expected to provide additional observational degrees of freedom related to cloud ice particle size.

A landscape scale valley confinement algorithm: Delineating unconfined valley bottoms for geomorphic, aquatic, and riparian applications

Treesearch

David E. Nagel; John M. Buffington; Sharon L. Parkes; Seth Wenger; Jaime R. Goode

2014-01-01

Valley confinement is an important landscape characteristic linked to aquatic habitat, riparian diversity, and geomorphic processes. This report describes a GIS program called the Valley Confinement Algorithm (VCA), which identifies unconfined valleys in montane landscapes. The algorithm uses nationally available digital elevation models (DEMs) at 10-30 m resolution to...

Graphene Nanobubbles as Valley Filters and Beam Splitters

NASA Astrophysics Data System (ADS)

Settnes, Mikkel; Power, Stephen R.; Brandbyge, Mads; Jauho, Antti-Pekka

2016-12-01

The energy band structure of graphene has two inequivalent valleys at the K and K' points of the Brillouin zone. The possibility to manipulate this valley degree of freedom defines the field of valleytronics, the valley analogue of spintronics. A key requirement for valleytronic devices is the ability to break the valley degeneracy by filtering and spatially splitting valleys to generate valley polarized currents. Here, we suggest a way to obtain valley polarization using strain-induced inhomogeneous pseudomagnetic fields (PMFs) that act oppositely on the two valleys. Notably, the suggested method does not involve external magnetic fields, or magnetic materials, unlike previous proposals. In our proposal the strain is due to experimentally feasible nanobubbles, whose associated PMFs lead to different real space trajectories for K and K' electrons, thus allowing the two valleys to be addressed individually. In this way, graphene nanobubbles can be exploited in both valley filtering and valley splitting devices, and our simulations reveal that a number of different functionalities are possible depending on the deformation field.

Millimeter wave backscatter measurements in support of collision avoidance applications

NASA Astrophysics Data System (ADS)

Narayanan, Ram M.; Snuttjer, Brett R. J.

1997-11-01

Millimeter-wave short range radar systems have unique advantages in surface navigation applications, such as military vehicle mobility, aircraft landing assistance, and automotive collision avoidance. In collision avoidance applications, characterization of clutter due to terrain and roadside objects is necessary in order to maximize the signal-to-clutter ratio (SCR) and to minimize false alarms. The results of two types of radar cross section (RCS) measurements at 95 GHz are reported in this paper. The first set of measurements presents data on the normalized RCS (NRCS) as well as clutter distributions of various terrain types at low grazing angles of 5° and 7.5°. The second set of measurements presents RCS data and statistics on various types of roadside objects, such as metallic and wooden sign posts. These results are expected to be useful for designers of short-range millimeter-wave collision avoidance radar systems.

The Long Valley Caldera GIS database

USGS Publications Warehouse

Battaglia, Maurizio; Williams, M.J.; Venezky, D.Y.; Hill, D.P.; Langbein, J.O.; Farrar, C.D.; Howle, J.F.; Sneed, M.; Segall, P.

2003-01-01

This database provides an overview of the studies being conducted by the Long Valley Observatory in eastern California from 1975 to 2001. The database includes geologic, monitoring, and topographic datasets related to Long Valley caldera. The CD-ROM contains a scan of the original geologic map of the Long Valley region by R. Bailey. Real-time data of the current activity of the caldera (including earthquakes, ground deformation and the release of volcanic gas), information about volcanic hazards and the USGS response plan are available online at the Long Valley observatory web page (http://lvo.wr.usgs.gov). If you have any comments or questions about this database, please contact the Scientist in Charge of the Long Valley observatory.

Comparison between Pixelated Scintillators: CsI(Tl), LaCl 3(Ce) and LYSO(Ce) when coupled to a Silicon Photomultipliers Array

NASA Astrophysics Data System (ADS)

Jeong, Manhee; Van, Benjamin; Wells, Byron T.; D'Aries, Lawrence J.; Hammig, Mark D.

2018-06-01

A large area SiPM array is individually coupled to five different types of scintillators in and each is evaluated for the development of a coded aperture imaging system. In order to readout signals from the 144 pixel array, a resistor network with symmetric charge division circuitry was developed, which successfully provides a significant reduction in the multiplicity of the analog outputs and reduces the size of the accumulated data. Energy resolutions at 662 keV for pixelated arrays of dimensions and material types as follows: 3 × 3 × 20 mm3 CsI(Tl), 4 × 4 × 20 mm3 CsI(Tl), 4 × 4 × 5 mm3 LYSO(Ce), 4 × 4 × 10 mm3 LYSO(Ce), and 2 × 2 × 5 mm3 LaCl3(Ce) have been determined. In addition, sub-millimeter FWHM pixel-identification resolutions were acquired from all of the scintillators tested.

Millimeter Wave Spectroscopy in a Semi-Confocal Fabry-Perot Cavity

NASA Astrophysics Data System (ADS)

Drouin, Brian; Tang, Adrian; Reck, Theodore J.; Nemchick, Deacon J.; Cich, Matthew J.; Crawford, Timothy J.; Raymond, Alexander W.; Chang, M.-C. Frank; Kim, Rod M.

2017-06-01

A new generation of CMOS circuits operating at 89-104 GHz with improved output power and pulse switch isolation have enhanced the performance of the miniaturized pulsed-echo Fourier transform spectrometer under development for planetary exploration at the Jet Propulsion laboratory. Additional progress has been made by creating a waveguide-fed structure for the novel planar coupler design. This structure has enabled characterization of each component in the system and enabled spectroscopy to be done with conventional millimeter hardware that enables (1) direct comparisons to the CMOS components, (2) enhanced bandwidth of 74-109 GHz, and (3) amplification of the transmitter prior to cavity injection. We have now demonstrated the technique with room temperature detections on multiple species including N_2O, OCS, CH_3CN, CH_3OH, CH_3NH_2, CH_3CHO, CH_3Cl, HDO, D_2O, CH_3CH_2CN and CH_3CH_2OH. Of particular interest to spectroscopic work in the millimeter range is the ongoing incorporation of a ΔΣ radio-frequency source into the millimeter-wave lock-loop - this has improved the phase-noise of the tunable CMOS transceiver to better than the room-temperature Doppler limit and provides a promising source for general use that may replace the high end microwave synthesizers. We are in the process of building a functional interface to the various subsystems. We will present a trade-space study to determine the optimal operating conditions of the pulse-echo system.

Apparatus for millimeter-wave signal generation

DOEpatents

Vawter, G. Allen; Hietala, Vincent M.; Zolper, John C.; Mar, Alan; Hohimer, John P.

1999-01-01

An opto-electronic integrated circuit (OEIC) apparatus is disclosed for generating an electrical signal at a frequency .gtoreq.10 GHz. The apparatus, formed on a single substrate, includes a semiconductor ring laser for generating a continuous train of mode-locked lasing pulses and a high-speed photodetector for detecting the train of lasing pulses and generating the electrical signal therefrom. Embodiments of the invention are disclosed with an active waveguide amplifier coupling the semiconductor ring laser and the high-speed photodetector. The invention has applications for use in OEICs and millimeter-wave monolithic integrated circuits (MMICs).

Conversion loss and noise of microwave and millimeter-wave mixers. I - Theory. II - Experiment

NASA Technical Reports Server (NTRS)

Held, D. N.; Kerr, A. R.

1978-01-01

The conversion loss and noise of microwave and millimeter-wave mixers are analyzed. Nonlinear capacitance, arbitrary embedding impedances, as well as shot, thermal and scattering noise arising in the diode, figure in the analysis. The anomalous mixer noise noted in millimeter-wave mixers by Kerr (1975) is shown to be explainable in terms of the correlation of down-converted components of the time-varying shot noise. A digital computer analysis of the conversion loss, noise, and output impedance of an 80-120-GHz mixer is also conducted.

Polarization-based material classification technique using passive millimeter-wave polarimetric imagery.

PubMed

Hu, Fei; Cheng, Yayun; Gui, Liangqi; Wu, Liang; Zhang, Xinyi; Peng, Xiaohui; Su, Jinlong

2016-11-01

The polarization properties of thermal millimeter-wave emission capture inherent information of objects, e.g., material composition, shape, and surface features. In this paper, a polarization-based material-classification technique using passive millimeter-wave polarimetric imagery is presented. Linear polarization ratio (LPR) is created to be a new feature discriminator that is sensitive to material type and to remove the reflected ambient radiation effect. The LPR characteristics of several common natural and artificial materials are investigated by theoretical and experimental analysis. Based on a priori information about LPR characteristics, the optimal range of incident angle and the classification criterion are discussed. Simulation and measurement results indicate that the presented classification technique is effective for distinguishing between metals and dielectrics. This technique suggests possible applications for outdoor metal target detection in open scenes.

Millimeter-wave Absorption Studies of Molecules in Diffuse Clouds

NASA Astrophysics Data System (ADS)

Lucas, Robert; Liszt, Harvey S.

1999-10-01

With IRAM instruments in the last few years, we have been using compact extragalactic millimeter wave radio sources as background objects to study the absorption spectrum of diffuse interstellar gas at millimeter wavelengths. The molecular content of interstellar gas has turned out to be unexpectedly rich. Simple polyatomic molecules such as HCO+, C2H are quite ubiquitous near the Galactic plane (beta < 15o), and many species are detected in some directions (CO, HCO+, H2CO, HCN, HNC, CN, C2H, C3H2, H2S, CS, HCS+, SO, SiO). Remarkable proportionality relations are found between related species such as HCO+ and OH, or CN, HCN and HNC. The high abundance of some species is still a challenge for current models of diffuse cloud chemistry. A factor of 10 increase in the sensitivity will make such studies achievable in denser clouds, where the chemistry is still more active and where abundances are nowadays only available by emission measurements, and thus subject to uncertainties due to sometimes poorly understood line formation and excitation conditions.

A superconducting tunnel junction receiver for millimeter-wave astronomy

NASA Technical Reports Server (NTRS)

Pan, S. K.; Kerr, A. R.

1986-01-01

The development and construction of an ultralow noise heterodyne receiver for millimeter wave astronomy is described along with its use for 115.3 GHz Co line observations. The receiver uses a Superconductor-Insulator-Superconductor (SIS) quasiparticle tunnel junction mixer to convert the millimeter wave signal to a microwave intermediate frequency. Experiments aimed at quantitative verification of J. R. Tucker's quantum mixer theory are studied, to see whether it could be used as the basis for the design of a practical receiver. The experimental results were in excellent agreement with the theory, assuming the three frequency approximation. Infinite available gain and negative output resistance were observed for the first time, nonclassical effects which are not seen in conventional diode mixers. Using Tucker's theory, an SIS receiver was then designed and constructed. At 115 GHz, the single sideband receiver noise temperature is 83K, the lowest ever reported in this frequency range. A CO survey toward Cygnus-X region, using this SIS receiver on the Columbia-GISS 4 ft. telescope, is also described.

Photocopy of photograph (original 35 millimeter negative in possession of ...

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

Photocopy of photograph (original 35 millimeter negative in possession of Luis Pumarada, San German, Puerto Rico). Luis Pumarada, Photographer, September 4, 1989. PUENTE RIO HONDO, VIEW FROM SOUTHWEST. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

A compendium of millimeter wave propagation studies performed by NASA

NASA Technical Reports Server (NTRS)

Kaul, R.; Rogers, D.; Bremer, J.

1977-01-01

Key millimeter wave propagation experiments and analytical results were summarized. The experiments were performed with the Ats-5, Ats-6 and Comstar satellites, radars, radiometers and rain gage networks. Analytic models were developed for extrapolation of experimental results to frequencies, locations, and communications systems.

27 CFR 9.78 - Ohio River Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ohio River Valley. 9.78... River Valley. (a) Name. The name of the viticultural area described in this section is “Ohio River Valley.” (b) Approved maps. The approved maps for determining the boundary of the Ohio River Valley...

Valley dependent transport in graphene L junction

NASA Astrophysics Data System (ADS)

Chan, K. S.

2018-05-01

We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

Water storage capacity of the natural river valley - how sedge communities influence it. Case study of Upper Biebrza Basin (Poland) based on ALS and TLS data

NASA Astrophysics Data System (ADS)

Brach, Marcin; Chormański, Jarosław

2014-05-01

The exact determination of water storage capacity in river valley is an important issue for hydrologists, ecologist and flood modellers. In case of natural river valley, the dense and complexity vegetation of the natural ecosystems can influence the proper identification of the water storage. Methods considered to be sufficient in other cases (urbanized, agricultural) may not produce correct results. Sedge communities in natural river valleys form characteristic tussocks, built from the species roots, other organic material and silt or mud. They are formed due to partial flooding during the inundation, so the plants can survive in hard, anaerobic conditions. They can growth even up to 0.5 meters, which is not so visible due to very dense vegetation in the valleys. These tussocks form a microtopography or a river valley. Currently, the most commonly used technology to register the terrain topography is an Airborne Laser Scanning (ALS), but in the case of the tussocks and the dense vegetation it generates high errors on elevation in the areas of the sedges (Carex appropinquata). This study concerns the Upper Biebrza Valley which is located in the northeastern Poland. For purpose of our work we used Terrestrial Laser Scanner (TLS) technology to determine microtopography of selected fields. Before measurements, the green part of the sedge was cut in selected measurements fields. It make possible to register only tussocks shape. Next, step was collection of the airborne ALS data of the valley with density of 8 points/sq m. The experimental field was divided on two sub-fields: one was cut and scanned using TLS before ALS collection, while the second after. Data collected as ALS and the TLS were then compared. The accuracy of the ALS data depends on the land cover of an area, while TLS accuracy is around 2 millimeters (when georeferenced it depends on the accuracy of reference points - in our case it was made using GPS RTK which gave us accuracy of few centimeters). The

Down in the Valley.

ERIC Educational Resources Information Center

Salter, Linda Graef

1999-01-01

Describes the partnerships formed by West Valley Mission Community College District (California) with its surrounding Silicon Valley business community in an effort to benefit workforce development. Asserts that community colleges are uniquely positioned to provide a lifelong education that will yield a skilled workforce to meet the needs of…

Functional ecology of an Antarctic Dry Valley

PubMed Central

Chan, Yuki; Van Nostrand, Joy D.; Zhou, Jizhong; Pointing, Stephen B.

2013-01-01

The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution. PMID:23671121

Functional ecology of an Antarctic Dry Valley.

PubMed

Chan, Yuki; Van Nostrand, Joy D; Zhou, Jizhong; Pointing, Stephen B; Farrell, Roberta L

2013-05-28

The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution.

Near millimeter wave characterization of dual mode materials

NASA Astrophysics Data System (ADS)

Stead, Michael; Simonis, George

1989-05-01

Nine materials which have application to both the millimeter and IR wavelength regions have been analyzed, and their indices of refraction and absorption coefficients have been determined in the 4-18/cm range. The lowest loss materials are found to be ALON and sapphire, and the highest loss samples to be ZnS and ZnSe. The mm-wave indices are all shown to be higher than their corresponding IR indices.

Inverse multipath fingerprinting for millimeter wave V2I beam alignment.

DOT National Transportation Integrated Search

2017-05-01

Efficient beam alignment is a crucial component in millimeter wave systems with analog beamforming, especially in fast-changing vehicular settings. This paper uses the vehicles position (e.g., available via GPS) to query the multipath fingerprint ...

Hazardous Waste Cleanup: West Valley Demonstration Project USDOE in West Valley, New York

EPA Pesticide Factsheets

The U.S. Department of Energy's West Valley Demonstration Project is located at 10282 Rock Spring Road in West Valley, New York. This is a 167 acre, Department of Energy (DOE)-operated portion of a 3,300-acre site owned by the New York State Energy

Frequency multiplexed superconducting quantum interference device readout of large bolometer arrays for cosmic microwave background measurements.

PubMed

Dobbs, M A; Lueker, M; Aird, K A; Bender, A N; Benson, B A; Bleem, L E; Carlstrom, J E; Chang, C L; Cho, H-M; Clarke, J; Crawford, T M; Crites, A T; Flanigan, D I; de Haan, T; George, E M; Halverson, N W; Holzapfel, W L; Hrubes, J D; Johnson, B R; Joseph, J; Keisler, R; Kennedy, J; Kermish, Z; Lanting, T M; Lee, A T; Leitch, E M; Luong-Van, D; McMahon, J J; Mehl, J; Meyer, S S; Montroy, T E; Padin, S; Plagge, T; Pryke, C; Richards, P L; Ruhl, J E; Schaffer, K K; Schwan, D; Shirokoff, E; Spieler, H G; Staniszewski, Z; Stark, A A; Vanderlinde, K; Vieira, J D; Vu, C; Westbrook, B; Williamson, R

2012-07-01

A technological milestone for experiments employing transition edge sensor bolometers operating at sub-Kelvin temperature is the deployment of detector arrays with 100s-1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ∼MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with superconducting quantum interference devices operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors.

Submillimeter Bolometer Array for the CSO

NASA Astrophysics Data System (ADS)

Wang, Ning; Hunter, T. R.; Benford, D. J.; Phillips, T. G.

We are building a bolometer array for use as a submillimeter continuum camera for the Caltech Submillimeter Observatory (CSO) located on Mauna Kea. This effort is a collaboration with Moseley et al. at Goddard Space Flight Center, who have developed the technique for fabricating monolithic bolometer arrays on Si wafers, as well as a sophisticated data taking system to use with these arrays (Moseley et al. 1984). Our primary goal is to construct a camera with 1x24 bolometer pixels operating at 350 and 450 microns using a 3He refrigerator. The monolithic bolometer arrays are fabricated using the techniques of photolithography and micromachining. Each pixel of the array is suspended by four thin Si legs 2 mm long and 12x14 square microns in cross section. These thin legs, obtained by wet Si etching, provide the weak thermal link between the bolometer pixel and the heat sink. A thermistor is formed on each bolometer pixel by P implantation compensated with 50% B. The bolometer array to be used for the camera will have a pixel size of 1x2 square millimeters, which is about half of the CSO beam size at a wavelength of 400 microns. We plan to use mirrors to focus the beam onto the pixels intead of Winston cones. In order to eliminate background radiation from warm surroundings reaching the bolometers, cold baffles will be inserted along the beam passages. To increase the bolometer absorption to radiation, a thin metal film will be deposited on the back of each bolometer pixel. It has been demonstrated that a proper impedance match of the bolometer element can increase the bolometer absorption efficiency to about 50% (Clarke et al., 1978). The use of baffle approach to illumination will make it easier for us to expand to more pixels in the future. The first stage amplification will be performed with cold FETs, connected to each bolometer pixel. Signals from each bolometer will be digitized using a 16 bit A/D with differential inputs. The digitizing frequency will be up to

Volcanological perspectives on Long Valley, Mammoth Mountain, and Mono Craters: Several contiguous but discrete systems

USGS Publications Warehouse

Hildreth, W.

2004-01-01

The volcanic history of the Long Valley region is examined within a framework of six successive (spatially discrete) foci of silicic magmatism, each driven by locally concentrated basaltic intrusion of the deep crust in response to extensional unloading and decompression melting of the upper mantle. A precaldera dacite field (3.5-2.5 Ma) northwest of the later site of Long Valley and the Glass Mountain locus of >60 high-silica rhyolite vents (2.2-0.79 Ma) northeast of it were spatially and temporally independent magmatic foci, both cold in postcaldera time. Shortly before the 760-ka caldera-forming eruption, the mantle-driven focus of crustal melting shifted ???20 km westward, abandoning its long-stable position under Glass Mountain and energizing instead the central Long Valley system that released 600 km3 of compositionally zoned rhyolitic Bishop Tuff (760 ka), followed by ???100 km3 of crystal-poor Early Rhyolite (760-650 ka) on the resurgent dome and later by three separate 5-unit clusters of varied Moat Rhyolites of small volume (527-101 ka). West of the caldera ring-fault zone, a fourth focus started up ???160 ka, producing a 10??20-km array of at least 35 mafic vents that surround the trachydacite/alkalic rhyodacite Mammoth Mountain dome complex at its core. This young 70-vent system lies west of the structural caldera and (though it may have locally re-energized the western margin of the mushy moribund Long Valley reservoir) represents a thermally and compositionally independent focus. A fifth major discrete focus started up by ???50 ka, 25-30 km north of Mammoth Mountain, beneath the center of what has become the Mono Craters chain. In the Holocene, this system advanced both north and south, producing ???30 dike-fed domes of crystal-poor high-silica rhyolite, some as young as 650 years. The nearby chain of mid-to-late Holocene Inyo domes is a fault-influenced zone of mixing where magmas of at least four kinds are confluent. The sixth and youngest focus is

Design of a Millimeter-Wave Concentrator for Beam Reception in High-Power Wireless Power Transfer

NASA Astrophysics Data System (ADS)

Fukunari, Masafumi; Wongsuryrat, Nat; Yamaguchi, Toshikazu; Nakamura, Yusuke; Komurasaki, Kimiya; Koizumi, Hiroyuki

2017-02-01

This study examined the performance of a developed taper-tube concentrator for 94-GHz millimeter-wave beam reception during wireless power transfer. The received energy is converted into kinetic energy of a working gas in the tube to drive an engine or thruster. The concentrator, which is assumed to have mirror reflection of millimeter waves in it, is designed to be shorter than conventional tapered waveguides of millimeter waves. A dimensionless design law of a concentrator is proposed based on geometric optics theory. Because the applicability of geometric optics theory is unclear, the ratio of its bore diameter to its wavelength was set as small compared to those in other possible applications. Then, the discrepancy between the designed and measured power reception was examined. Results show that the maximum discrepancy was as low as 7 % for the bore-to-wavelength ratio of 20 at the narrow end of the concentrator.

Embedded electronics for a video-rate distributed aperture passive millimeter-wave imager

NASA Astrophysics Data System (ADS)

Curt, Petersen F.; Bonnett, James; Schuetz, Christopher A.; Martin, Richard D.

2013-05-01

Optical upconversion for a distributed aperture millimeter wave imaging system is highly beneficial due to its superior bandwidth and limited susceptibility to EMI. These features mean the same technology can be used to collect information across a wide spectrum, as well as in harsh environments. Some practical uses of this technology include safety of flight in degraded visual environments (DVE), imaging through smoke and fog, and even electronic warfare. Using fiber-optics in the distributed aperture poses a particularly challenging problem with respect to maintaining coherence of the information between channels. In order to capture an image, the antenna aperture must be electronically steered and focused to a particular distance. Further, the state of the phased array must be maintained, even as environmental factors such as vibration, temperature and humidity adversely affect the propagation of the signals through the optical fibers. This phenomenon cannot be avoided or mitigated, but rather must be compensated for using a closed-loop control system. In this paper, we present an implementation of embedded electronics designed specifically for this purpose. This novel architecture is efficiently small, scalable to many simultaneously operating channels and sufficiently robust. We present our results, which include integration into a 220 channel imager and phase stability measurements as the system is stressed according to MIL-STD-810F vibration profiles of an H-53E heavy-lift helicopter.

Photocopy of photograph (original 35 millimeter negative in possession of ...

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

Photocopy of photograph (original 35 millimeter negative in possession of Luis Pumarada, San German, Puerto Rico). Luis Pumarada, Photographer, September 4, 1989. PUENTE RIO HONDO, DOMED PLATE DECK FROM BELOW. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

Photocopy of photograph (original 35 millimeter negative in possession of ...

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

Photocopy of photograph (original 35 millimeter negative in possession of Luis Pumarada, San German, Puerto Rico). Luis Pumarada, Photographer, September 4, 1989. PUENTE RIO HONDO, VIEW OF SOUTH ABUTMENT. - Puente Rio Hondo, Spanning Hondo River on PR Road 156, Barrio Rio Hondo, Comerio, Comerio Municipio, PR

Rift Valley Fever Virus

USDA-ARS?s Scientific Manuscript database

Rift Valley fever virus (RVFV) is a mosquito-transmitted virus or arbovirus that is endemic in sub-Saharan Africa. In the last decade, Rift Valley fever (RVF) outbreaks have resulted in loss of human and animal life, as well as had significant economic impact. The disease in livestock is primarily a...

Status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera

NASA Astrophysics Data System (ADS)

Golwala, Sunil R.; Bockstiegel, Clint; Brugger, Spencer; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran; Gao, Jiansong; Gill, Amandeep K.; Glenn, Jason; Hollister, Matthew I.; LeDuc, Henry G.; Maloney, Philip R.; Mazin, Benjamin A.; McHugh, Sean G.; Miller, David; Noroozian, Omid; Nguyen, Hien T.; Sayers, Jack; Schlaerth, James A.; Siegel, Seth; Vayonakis, Anastasios K.; Wilson, Philip R.; Zmuidzinas, Jonas

2012-09-01

We present the status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera, a new instrument for the Caltech Submillimeter Observatory. MUSIC is designed to have a 14', diffraction-limited field-of-view instrumented with 2304 detectors in 576 spatial pixels and four spectral bands at 0.87, 1.04, 1.33, and 1.98 mm. MUSIC will be used to study dusty star-forming galaxies, galaxy clusters via the Sunyaev-Zeldovich effect, and star formation in our own and nearby galaxies. MUSIC uses broadband superconducting phased-array slot-dipole antennas to form beams, lumpedelement on-chip bandpass filters to define spectral bands, and microwave kinetic inductance detectors to sense incoming light. The focal plane is fabricated in 8 tiles consisting of 72 spatial pixels each. It is coupled to the telescope via an ambient-temperature ellipsoidal mirror and a cold reimaging lens. A cold Lyot stop sits at the image of the primary mirror formed by the ellipsoidal mirror. Dielectric and metal-mesh filters are used to block thermal infrared and out-ofband radiation. The instrument uses a pulse tube cooler and 3He/ 3He/4He closed-cycle cooler to cool the focal plane to below 250 mK. A multilayer shield attenuates Earth's magnetic field. Each focal plane tile is read out by a single pair of coaxes and a HEMT amplifier. The readout system consists of 16 copies of custom-designed ADC/DAC and IF boards coupled to the CASPER ROACH platform. We focus on recent updates on the instrument design and results from the commissioning of the full camera in 2012.

Content-Based Multi-Channel Network Coding Algorithm in the Millimeter-Wave Sensor Network

PubMed Central

Lin, Kai; Wang, Di; Hu, Long

2016-01-01

With the development of wireless technology, the widespread use of 5G is already an irreversible trend, and millimeter-wave sensor networks are becoming more and more common. However, due to the high degree of complexity and bandwidth bottlenecks, the millimeter-wave sensor network still faces numerous problems. In this paper, we propose a novel content-based multi-channel network coding algorithm, which uses the functions of data fusion, multi-channel and network coding to improve the data transmission; the algorithm is referred to as content-based multi-channel network coding (CMNC). The CMNC algorithm provides a fusion-driven model based on the Dempster-Shafer (D-S) evidence theory to classify the sensor nodes into different classes according to the data content. By using the result of the classification, the CMNC algorithm also provides the channel assignment strategy and uses network coding to further improve the quality of data transmission in the millimeter-wave sensor network. Extensive simulations are carried out and compared to other methods. Our simulation results show that the proposed CMNC algorithm can effectively improve the quality of data transmission and has better performance than the compared methods. PMID:27376302

An evaluation of Skylab (EREP) remote sensing techniques applied to investigation of crustal structure. [Death Valley and Greenwater Valley (CA)

NASA Technical Reports Server (NTRS)

Bechtold, I. C. (Principal Investigator)

1974-01-01

The author has identified the following significant results. A study of Greenwater Valley indicates that the valley is bounded on the north and east by faults, on the south by a basement high, and on the west by the dip slope of the black mountains, movement of ground water from the valley is thus Movement of ground water from the valley is thus restricted, indicating the valley is a potential water reservoir.

Josephson frequency meter for millimeter and submillimeter wavelengths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anischenko, S.E.; Larkin, S.Y.; Chaikovsky, V.I.

1994-12-31

Frequency measurements of electromagnetic oscillations of millimeter and submillimeter wavebands with frequency growth due to a number of reasons become more and more difficult. First, these frequencies are considered to be cutoff for semiconductor converting devices and one has to use optical measurement methods instead of traditional ones with frequency transfer. Second, resonance measurement methods are characterized by using relatively narrow bands and optical ones are limited in frequency and time resolution due to the limited range and velocity of movement of their mechanical elements as well as the efficiency of these optical techniques decreases with the increase of wavelengthmore » due to diffraction losses. That requires the apriori information on the radiation frequency band of the source involved. Method of measuring frequency of harmonic microwave signals in millimeter and submillimeter wavebands based on the ac Josephson effect in superconducting contacts is devoid of all the above drawbacks. This approach offers a number of major advantages over the more traditional measurement methods, that is the one based on frequency conversion, resonance and interferrometric techniques. It can be characterized by high potential accuracy, wide range of frequencies measured, prompt measurement and the opportunity to obtain panoramic display of the results as well as full automation of the measuring process.« less

Josephson frequency meter for millimeter and submillimeter wavelengths

NASA Technical Reports Server (NTRS)

Anischenko, S. E.; Larkin, S. Y.; Chaikovsky, V. I.; Kabayev, P. V.; Kamyshin, V. V.

1995-01-01

Frequency measurements of electromagnetic oscillations of millimeter and submillimeter wavebands with frequency growth due to a number of reasons become more and more difficult. First, these frequencies are considered to be cutoffs for semiconductor converting devices and one has to use optical measurement methods instead of traditional ones with frequency transfer. Second, resonance measurement methods are characterized by using relatively narrow bands and optical ones are limited in frequency and time resolution due to the limited range and velocity of movement of their mechanical elements as well as the efficiency of these optical techniques decrease with the increase of wavelength due to diffraction losses. That requires a priori information on the radiation frequency band of the source involved. Method of measuring frequency of harmonic microwave signals in millimeter and submillimeter wavebands based on the ac Josephson effect in superconducting contacts is devoid of all the above drawbacks. This approach offers a number of major advantages over the more traditional measurement methods, that is one based on frequency conversion, resonance and interferometric techniques. It can be characterized by high potential accuracy, wide range of frequencies measured, prompt measurement and the opportunity to obtain a panoramic display of the results as well as full automation of the measuring process.

Millimeter Studies of Nearby Debris Disks

NASA Astrophysics Data System (ADS)

MacGregor, Meredith A.

2017-01-01

At least 20% of nearby main sequence stars are known to be surrounded by disks of dusty material resulting from the collisional erosion of planetesimals, larger bodies similar to asteroids and comets in our own Solar System. Since the dust-producing planetesimals are expected to persist in stable regions like belts and resonances, the locations, morphologies, and physical properties of dust in these ‘debris disks’ provide probes of planet formation and subsequent dynamical evolution. Observations at millimeter wavelengths are especially critical to our understanding of these systems, since the large grains that dominate emission at these long wavelengths do not travel far from their origin and therefore reliably trace the underlying planetesimal distribution. The newly upgraded capabilities of millimeter interferometers like ALMA are providing us with the opportunity to image these disks with unprecedented sensitivity and resolution. In this dissertation talk, I will present my ongoing work, which uses observations of the angularly resolved brightness distribution and the spectral dependence of the flux density to constrain both the structure and grain size distribution of a sample of nearby debris disks. I will present constraints on the position, width, surface density gradient, and any asymmetric structure of several debris disks (including Epsilon Eridani, Tau Ceti, and Fomalhaut) determined from ALMA and SMA observations. In addition, I will present the results of a survey using the VLA and ATCA to measure the long wavelength spectral index and thus the grain size distribution of fifteen debris disks. Together these results provide a foundation to investigate the dynamical evolution of planetary systems through multi-wavelength observations of debris disks.

Simulation of millimeter-wave body images and its application to biometric recognition

NASA Astrophysics Data System (ADS)

Moreno-Moreno, Miriam; Fierrez, Julian; Vera-Rodriguez, Ruben; Parron, Josep

2012-06-01

One of the emerging applications of the millimeter-wave imaging technology is its use in biometric recognition. This is mainly due to some properties of the millimeter-waves such as their ability to penetrate through clothing and other occlusions, their low obtrusiveness when collecting the image and the fact that they are harmless to health. In this work we first describe the generation of a database comprising 1200 synthetic images at 94 GHz obtained from the body of 50 people. Then we extract a small set of distance-based features from each image and select the best feature subsets for person recognition using the SFFS feature selection algorithm. Finally these features are used in body geometry authentication obtaining promising results.

27 CFR 9.154 - Chiles Valley.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Chiles Valley. (a) Name. The name of the viticultural area described in this section is “Chiles Valley... viticultural area are four 1:24,000 Scale U.S.G.S. topography maps. They are titled: (1) St. Helena, CA 1960 photorevised 1980; (2) Rutherford, CA 1951 photorevised 1968; (3) Chiles Valley, CA 1958 photorevised 1980; (4...

Meter-Scale Characteristics of Martian Channels and Valleys

USGS Publications Warehouse

Carr, M.H.; Malin, M.C.

2000-01-01

Mars Global Surveyor images, with resolutions as high as 1.5 m pixel, enable characterization of martian channels and valleys at resolutions one to two orders of magnitude better than was previously possible. A major surprise is the near-absence of valleys a few hundred meters wide and narrower. The almost complete absence of fine-scale valleys could be due to lack of precipitation, destruction of small valleys by erosion, or dominance of infiltration over surface runoff. V-shaped valleys with a central channel, such as Nanedi Vallis, provide compelling evidence for sustained or episodic flow of water across the surface. Larger valleys appear to have formed not by headward erosion as a consequence of groundwater sapping but by erosion from water sources upstream of the observed sections. The freshest appearing valleys have triangular cross sections, with talus from opposing walls meeting at the center of the valley. The relations suggest that the width of the valleys is controlled by the depth of incision and the angle of repose of the walls. The flat floors of less fresh-appearing valleys result primarily from later eolian fill. Several discontinuous valleys and lines of craters suggest massive subsurface solution or erosion. The climatic implications of the new images will remain obscure until the cause for the scarcity of fine-scale dissection is better understood. ?? 2000 Academic Press.

Millimeter-scale liquid metal droplet thermal switch

NASA Astrophysics Data System (ADS)

Yang, Tianyu; Kwon, Beomjin; Weisensee, Patricia B.; Kang, Jin Gu; Li, Xuejiao; Braun, Paul; Miljkovic, Nenad; King, William P.

2018-02-01

Devices capable of actively controlling heat flow have been desired by the thermal management community for decades. The need for thermal control has become particularly urgent with power densification resulting in devices with localized heat fluxes as high as 1 kW/cm2. Thermal switches, capable of modulating between high and low thermal conductances, enable the partitioning and active control of heat flow pathways. This paper reports a millimeter-scale thermal switch with a switching ratio >70, at heat fluxes near 10 W/cm2. The device consists of a silicone channel filled with a reducing liquid or vapor and an immersed liquid metal Galinstan slug. Galinstan has a relatively high thermal conductivity (≈16.5 W/mK at room temperature), and its position can be manipulated within the fluid channel, using either hydrostatic pressure or electric fields. When Galinstan bridges the hot and cold reservoirs (the "ON" state), heat flows across the channel. When the hot and cold reservoirs are instead filled with the encapsulating liquid or vapor (the "OFF" state), the cross-channel heat flow significantly reduces due to the lower thermal conductivity of the solution (≈0.03-0.6 W/mK). We demonstrate switching ratios as high as 15.6 for liquid filled channels and 71.3 for vapor filled channels. This work provides a framework for the development of millimeter-scale thermal switches and diodes capable of spatial and temporal control of heat flows.

Microscopic Identification of Prokaryotes in Modern and Ancient Halite, Saline Valley and Death Valley, California

NASA Astrophysics Data System (ADS)

Schubert, Brian A.; Lowenstein, Tim K.; Timofeeff, Michael N.

2009-06-01

Primary fluid inclusions in halite crystallized in Saline Valley, California, in 1980, 2004-2005, and 2007, contain rod- and coccoid-shaped microparticles the same size and morphology as archaea and bacteria living in modern brines. Primary fluid inclusions from a well-dated (0-100,000 years), 90 m long salt core from Badwater Basin, Death Valley, California, also contain microparticles, here interpreted as halophilic and halotolerant prokaryotes. Prokaryotes are distinguished from crystals on the basis of morphology, optical properties (birefringence), and uniformity of size. Electron micrographs of microparticles from filtered modern brine (Saline Valley), dissolved modern halite crystals (Saline Valley), and dissolved ancient halite crystals (Death Valley) support in situ microscopic observations that prokaryotes are present in fluid inclusions in ancient halite. In the Death Valley salt core, prokaryotes in fluid inclusions occur almost exclusively in halite precipitated in perennial saline lakes 10,000 to 35,000 years ago. This suggests that trapping and preservation of prokaryotes in fluid inclusions is influenced by the surface environment in which the halite originally precipitated. In all cases, prokaryotes in fluid inclusions in halite from the Death Valley salt core are miniaturized (<1 μm diameter cocci, <2.5 μm long, very rare rod shapes), which supports interpretations that the prokaryotes are indigenous to the halite and starvation survival may be the normal response of some prokaryotes to entrapment in fluid inclusions for millennia. These results reinforce the view that fluid inclusions in halite and possibly other evaporites are important repositories of microbial life and should be carefully examined in the search for ancient microorganisms on Earth, Mars, and elsewhere in the Solar System.

Synergism of Dewetting and Self-Wrinkling To Create Two-Dimensional Ordered Arrays of Functional Microspheres.

PubMed

Han, Xue; Hou, Jing; Xie, Jixun; Yin, Jian; Tong, Yi; Lu, Conghua; Möhwald, Helmuth

2016-06-29

Here we report a simple, novel, yet robust nonlithographic method for the controlled fabrication of two-dimensional (2-D) ordered arrays of polyethylene glycol (PEG) microspheres. It is based on the synergistic combination of two bottom-up processes enabling periodic structure formation for the first time: dewetting and the mechanical wrinkle formation. The deterministic dewetting results from the hydrophilic polymer PEG on an incompatible polystyrene (PS) film bound to a polydimethylsiloxane (PDMS) substrate, which is directed both by a wrinkled template and by the template-directed in-situ self-wrinkling PS/PDMS substrate. Two strategies have been introduced to achieve synergism to enhance the 2-D ordering, i.e., employing 2-D in-situ self-wrinkling substrates and boundary conditions. As a result, we achieve highly ordered 2-D arrays of PEG microspheres with desired self-organized microstructures, such as the array location (e.g., selectively on the crest/in the valley of the wrinkles), diameter, spacing of the microspheres, and array direction. Additionally, the coordination of PEG with HAuCl4 is utilized to fabricate 2-D ordered arrays of functional PEG-HAuCl4 composite microspheres, which are further converted into different Au nanoparticle arrays. This simple versatile combined strategy could be extended to fabricate highly ordered 2-D arrays of other functional materials and achieve desirable properties and functionalities.

Development and Short-Range Testing of a 100 kW Side-Illuminated Millimeter-Wave Thermal Rocket

NASA Technical Reports Server (NTRS)

Bruccoleri, Alexander; Eilers, James A.; Lambot, Thomas; Parkin, Kevin

2015-01-01

The objective of the phase described here of the Millimeter-Wave Thermal Launch System (MTLS) Project was to launch a small thermal rocket into the air using millimeter waves. The preliminary results of the first MTLS flight vehicle launches are presented in this work. The design and construction of a small thermal rocket with a planar ceramic heat exchanger mounted along the axis of the rocket is described. The heat exchanger was illuminated from the side by a millimeter-wave beam and fed propellant from above via a small tank containing high pressure argon or nitrogen. Short-range tests where the rocket was launched, tracked, and heated with the beam are described. The rockets were approximately 1.5 meters in length and 65 millimeters in diameter, with a liftoff mass of 1.8 kilograms. The rocket airframes were coated in aluminum and had a parachute recovery system activated via a timer and Pyrodex. At the rocket heat exchanger, the beam distance was 40 meters with a peak power intensity of 77 watts per square centimeter. and a total power of 32 kilowatts in a 30 centimeter diameter circle. An altitude of approximately 10 meters was achieved. Recommendations for improvements are discussed.

Valley Vortex States in Sonic Crystals

NASA Astrophysics Data System (ADS)

Lu, Jiuyang; Qiu, Chunyin; Ke, Manzhu; Liu, Zhengyou

2016-03-01

Valleytronics is quickly emerging as an exciting field in fundamental and applied research. In this Letter, we study the acoustic version of valley states in sonic crystals and reveal a vortex nature of such states. In addition to the selection rules established for exciting valley polarized states, a mimicked valley Hall effect of sound is proposed further. The extraordinary chirality of valley vortex states, detectable in experiments, may open a new possibility in sound manipulations. This is appealing to scalar acoustics that lacks a spin degree of freedom inherently. In addition, the valley selection enables a handy way to create vortex matter in acoustics, in which the vortex chirality can be controlled flexibly. Potential applications can be anticipated with the exotic interaction of acoustic vortices with matter, such as to trigger the rotation of the trapped microparticles without contact.

Topological Valley Transport in Two-dimensional Honeycomb Photonic Crystals.

PubMed

Yang, Yuting; Jiang, Hua; Hang, Zhi Hong

2018-01-25

Two-dimensional photonic crystals, in analogy to AB/BA stacking bilayer graphene in electronic system, are studied. Inequivalent valleys in the momentum space for photons can be manipulated by simply engineering diameters of cylinders in a honeycomb lattice. The inequivalent valleys in photonic crystal are selectively excited by a designed optical chiral source and bulk valley polarizations are visualized. Unidirectional valley interface states are proved to exist on a domain wall connecting two photonic crystals with different valley Chern numbers. With the similar optical vortex index, interface states can couple with bulk valley polarizations and thus valley filter and valley coupler can be designed. Our simple dielectric PC scheme can help to exploit the valley degree of freedom for future optical devices.

Diagnosis and Treatment of Neurological Disorders by Millimeter-Wave Stimulation

NASA Technical Reports Server (NTRS)

Siegel, Peter H.; Pikov, Victor

2011-01-01

Increasingly, millimeter waves are being employed for telecomm, radar, and imaging applications. To date in the U.S, however, very few investigations on the impact of this radiation on biological systems at the cellular level have been undertaken. In the beginning, to examine the impact of millimeter waves on cellular processes, researchers discovered that cell membrane depolarization may be triggered by low levels of integrated power at these high frequencies. Such a situation could be used to advantage in the direct stimulation of neuronal cells for applications in neuroprosthetics and diagnosing or treating neurological disorders. An experimental system was set up to directly monitor cell response on exposure to continuous-wave, fixed-frequency, millimeter-wave radiation at low and modest power levels (0.1 to 100 safe exposure standards) between 50 and 100 GHz. Two immortalized cell lines derived from lung and neuronal tissue were transfected with green fluorescent protein (GFP) that locates on the inside of the cell membrane lipid bi-layer. Oxonol dye was added to the cell medium. When membrane depolarization occurs, the oxonal bound to the outer wall of the lipid bi-layer can penetrate close to the inner wall where the GFP resides. Under fluorescent excitation (488 nm), the normally green GFP (520 nm) optical signal quenches and gives rise to a red output when the oxonol comes close enough to the GFP to excite a fluorescence resonance energy transfer (FRET) with an output at 620 nm. The presence of a strong FRET signature upon exposures of 30 seconds to 2 minutes at 5-10 milliwatts per square centimeter RF power at 50 GHz, followed by a return to the normal 520-nm GFP signal after a few minutes indicating repolarization of the membrane, indicates that low levels of RF energy may be able to trigger non-destructive membrane depolarization without direct cell contact. Such a mechanism could be used to stimulate neuronal cells in the cortex without the need for

Optical tuning of electronic valleys (Conference Presentation)

NASA Astrophysics Data System (ADS)

Sie, Edbert J.; Gedik, Nuh

2017-02-01

Monolayer transition-metal dichalcogenides such as MoS2 and WS2 are prime examples of atomically thin semiconducting crystals that exhibit remarkable electronic and optical properties. They have a pair of valleys that can serve as a new electronic degree of freedom, and these valleys obey optical selection rules with circularly polarized light. Here, we discuss how ultrafast laser pulses can be used to tune their energy levels in a controllable valley-selective manner. The energy tunability is extremely large, comparable to what would be obtained using a hundred Tesla of magnetic field. We will also show that such valley tunability can be performed while we effectively manipulate the valley selection rules. Finally, we will explore the prospect of using this technique through photoemission spectroscopy to create a new phase of matter called a valley Floquet topological insulator.

Dynamic scheduling and planning parallel observations on large Radio Telescope Arrays with the Square Kilometre Array in mind

NASA Astrophysics Data System (ADS)

Buchner, Johannes

2011-12-01

literature: The inability of a GA to properly improve schedules and the generation of schedules with frequent interruptions. Finally, we demonstrate the scheduling framework for several operating telescopes: (1) Dynamic re-scheduling with the AUT Warkworth 12m telescope, (2) Scheduling for the Australian Mopra 22m telescope and scheduling for the Allen Telescope Array. Furthermore, we discuss the applicability of the presented scheduling framework to the Atacama Large Millimeter/submillimeter Array (ALMA, in construction) and the SKA. In particular, during the development phase of the SKA, this dynamic, scalable scheduling framework can accommodate changing conditions.

Martian oceans, valleys and climate

USGS Publications Warehouse

Carr, M.H.

2000-01-01

The new Mars Global Surveyor altimetry shows that the heavily cratered southern hemisphere of Mars is 5 km higher that the sparely cratered plains of the northern hemisphere. Previous suggestions that oceans formerly occupied that northern plains as evidenced by shorelines are partly supported by the new data. A previously identified outer boundary has a wide range of elevations and is unlikely to be a shoreline but an inner contact with a narrow range of elevations is a more likely candidate. No shorelines are visible in the newly acquired, 2.5 metre/pixel imaging. Newly imaged valleys provide strong support for sustained or episodic flow of water across the Martian surface. A major surprise, however, is the near absence of valleys less than 100 m across. Martian valleys seemingly do not divide into ever smaller valleys as terrestrial valleys commonly do. This could be due to lack of precipitation or lack of surface runoff because of high infiltration rates. High erosion rates and supports warm climates and presence of large bodies of water during heavy bombardment. The climate history and fate of the water after heavy bombardment remain cotroversial.

An Expanded Very Large Array and CARMA Study of Dusty Disks and Torii with Large Grains in Dying Stars

NASA Astrophysics Data System (ADS)

Sahai, R.; Claussen, M. J.; Schnee, S.; Morris, M. R.; Sánchez Contreras, C.

2011-09-01

We report the results of a pilot multiwavelength survey in the radio continuum (X, Ka, and Q bands, i.e., from 3.6 cm to 7 mm) carried out with the Expanded Very Large Array (EVLA) in order to confirm the presence of very large dust grains in dusty disks and torii around the central stars in a small sample of post-asymptotic giant branch (pAGB) objects, as inferred from millimeter (mm) and submillimeter (submm) observations. Supporting mm-wave observations were also obtained with the Combined Array for Research in Millimeter-wave Astronomy toward three of our sources. Our EVLA survey has resulted in a robust detection of our most prominent submm emission source, the pre-planetary nebula (PPN) IRAS 22036+5306, in all three bands, and the disk-prominent pAGB object, RV Tau, in one band. The observed fluxes are consistent with optically thin free-free emission, and since they are insignificant compared to their submm/mm fluxes, we conclude that the latter must come from substantial masses of cool, large (mm-sized) grains. We find that the power-law emissivity in the cm-to-submm range for the large grains in IRAS22036 is νβ, with β = 1-1.3. Furthermore, the value of β in the 3-0.85 mm range for the three disk-prominent pAGB sources (β <= 0.4) is significantly lower than that of IRAS22036, suggesting that the grains in pAGB objects with circumbinary disks are likely larger than those in the dusty waists of pre-planetary nebulae.

Knickpoints and Hanging Valleys of Licus Vallis, Mars

NASA Astrophysics Data System (ADS)

Goudge, T. A.; Fassett, C.

2016-12-01

Licus Vallis is a 350 km long valley system located along the dichotomy boundary on Mars. The main trunk of the valley is incised 200-700 m into the surrounding terrain. The valley heads at an outlet breach of a shallow, 30 km diameter impact crater, and is also fed by a system of tributaries incised into the plateau surrounding Licus Vallis. Many of the tributary valleys, as well as the main stem of the valley fed by the paleolake outlet, have profiles that are not smoothly graded, but rather have distinct reaches with concave downward topography. These sections are either knickpoints or hanging valleys that develop in response to changes in the effective local base level, changes in climate conditions during incision of the valley, or lithologic boundaries in the substrate. Here we present remote sensing observations from images and topography to test these competing hypotheses and further characterize the evolution of this large valley system. Slope-watershed area relationships for the tributaries and main trunk valley are used to distinguish between knickpoints and hanging valleys. Analysis of orbital images does not reveal any distinct layer above which knickpoints develop, and the elevation of knickpoints show no systematic trends that might be expected of a regional lithologic unit(s). Our preliminary results suggest that the distance of knickpoint retreat is correlated with the position of the tributary valley and not the watershed area. Downstream valleys have retreated the most, suggesting they have had the most time to adjust to lowering of the local base level associated with incision of the main valley. These results are most consistent with a wave of incision sweeping up the valley system as it adjusts to a low base level in the northern plains. This conclusion is also consistent with observations of the incision depth of Licus Vallis, which increases approximately linearly downstream. Understanding this signature of base level control on the incision

New insight on the water management in Ica Valley-Peru

NASA Astrophysics Data System (ADS)

Guttman, Joseph; Berger, Diego

2014-05-01

The Andes divide Peru into three natural drainage basins: Pacific basin, Atlantic basin and Lake Titicaca basin. According to the National Water Authority (ANA), the Pacific basin is the driest basin. The bulk of water that feed the local aquifers in the coastal Pacific region is coming from rivers that flow west from the Andes. One of them is the Ica River- source of the Ica Aquifer and the Pampas de Villacuri Aquifer. The Ica River flows in a graben that was created by a series of faults. The graben is filled with sand and gravel with interbeded and lenses of clay. The aquifer thickness varies between 25 meters to more than 200 meters. The Ica Valley has an extension of 7700 km2 and belongs to the Province of Ica, the second larger economic center in Peru. The Valley is located in the hyperarid region of the Southern Coastal area of Peru with a few millimeters of precipitation per year. The direct recharge is almost zero. The recharge into the Ica Valley aquifer is comes indirectly by infiltration of storm water through the riverbed generates in the Andes, through irrigation canals and by irrigation return flow. In this hyperarid region, local aquifers like the Ica Valley are extremely valuable resources to local populations and are the key sources of groundwater for agriculture and population needs. Therefore, these aquifers play a crucial role in providing people with water and intense attention should be given to manage the water sector properly and to keep the aquifer sustainable for future generations. The total pumping (from rough estimations) is much greater than the direct and indirect recharge. The deficit in the water balance is reflected in large water level decline, out of operation of shallow wells and the ascending of saline water from deeper layers. The change from flood irrigation that contributes about 35-40% of the water to the aquifer, to drip irrigation dramatically reduces the amount of water that infiltrates into the sub-surface from the

Piezo-generator integrating a vertical array of GaN nanowires.

PubMed

Jamond, N; Chrétien, P; Houzé, F; Lu, L; Largeau, L; Maugain, O; Travers, L; Harmand, J C; Glas, F; Lefeuvre, E; Tchernycheva, M; Gogneau, N

2016-08-12

We demonstrate the first piezo-generator integrating a vertical array of GaN nanowires (NWs). We perform a systematic multi-scale analysis, going from single wire properties to macroscopic device fabrication and characterization, which allows us to establish for GaN NWs the relationship between the material properties and the piezo-generation, and to propose an efficient piezo-generator design. The piezo-conversion of individual MBE-grown p-doped GaN NWs in a dense array is assessed by atomic force microscopy (AFM) equipped with a Resiscope module yielding an average output voltage of 228 ± 120 mV and a maximum value of 350 mV generated per NW. In the case of p-doped GaN NWs, the piezo-generation is achieved when a positive piezo-potential is created inside the nanostructures, i.e. when the NWs are submitted to compressive deformation. The understanding of the piezo-generation mechanism in our GaN NWs, gained from AFM analyses, is applied to design a piezo-generator operated under compressive strain. The device consists of NW arrays of several square millimeters in size embedded into spin-on glass with a Schottky contact for rectification and collection of piezo-generated carriers. The generator delivers a maximum power density of ∼12.7 mW cm(-3). This value sets the new state of the art for piezo-generators based on GaN NWs and more generally on nitride NWs, and offers promising prospects for the use of GaN NWs as high-efficiency ultra-compact energy harvesters.

Pre-flare association of magnetic fields and millimeter-wave radio emission

NASA Technical Reports Server (NTRS)

Mayfield, E. B.; White, K. P., III

1976-01-01

Observations of radio emission at 3.3 mm wavelength associated with magnetic fields in active regions are reported. Results of more than 200 regions during the years 1967-1968 show a strong correlation between peak enhanced millimeter emission, total flux of the longitudinal component of photospheric magnetic fields and the number of flares produced during transit of active regions. For magnetic flux greater than (10 to the 21st power) maxwells flares will occur and for flux of (10 to the 23rd power) maxwells the sum of the H-alpha flare importance numbers is about 40. The peak millimeter enhancement increases with magnetic flux for regions which subsequently flared. Estimates of the magnetic energy available and the correlation with flare production indicate that the photospheric fields and probably chromospheric currents are responsible for the observed pre-flare heating and provide the energy of flares.

THE FIRST VERY LONG BASELINE INTERFEROMETRY IMAGE OF A 44 GHz METHANOL MASER WITH THE KVN AND VERA ARRAY (KaVA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumoto, Naoko; Hirota, Tomoya; Honma, Mareki

2014-07-01

We have carried out the first very long baseline interferometry (VLBI) imaging of a 44 GHz class I methanol maser (7{sub 0}-6{sub 1} A {sup +}) associated with a millimeter core MM2 in a massive star-forming region IRAS 18151–1208 with KaVA (KVN and VERA Array), which is a newly combined array of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). We have succeeded in imaging compact maser features with a synthesized beam size of 2.7 milliarcseconds × 1.5 milliarcseconds (mas). These features are detected at a limited number of baselines within the length of shorter than ≈ 650 km corresponding to 100 Mλ in the uv-coverage.more » The central velocity and the velocity width of the 44 GHz methanol maser are consistent with those of the quiescent gas rather than the outflow traced by the SiO thermal line. The minimum component size among the maser features is ∼5 mas × 2 mas, which corresponds to the linear size of ∼15 AU × 6 AU assuming a distance of 3 kpc. The brightness temperatures of these features range from ∼3.5 × 10{sup 8} to 1.0 × 10{sup 10} K, which are higher than the estimated lower limit from a previous Very Large Array observation with the highest spatial resolution of ∼50 mas. The 44 GHz class I methanol maser in IRAS 18151–1208 is found to be associated with the MM2 core, which is thought to be less evolved than another millimeter core MM1 associated with the 6.7 GHz class II methanol maser.« less

Millimeter And Submillimeter-Wave Integrated Circuits On Quartz

NASA Technical Reports Server (NTRS)

Mehdi, Imran; Mazed, Mohammad; Siegel, Peter; Smith, R. Peter

1995-01-01

Proposed Quartz substrate Upside-down Integrated Device (QUID) relies on UV-curable adhesive to bond semiconductor with quartz. Integrated circuits including planar GaAs Schottky diodes and passive circuit elements (such as bandpass filters) fabricated on quartz substrates. Circuits designed to operate as mixers in waveguide circuit at millimeter and submillimeter wavelengths. Integrated circuits mechanically more robust, larger, and easier to handle than planar Schottky diode chips. Quartz substrate more suitable for waveguide circuits than GaAs substrate.

The investigation of using 5G millimeter-wave communications links for environmental monitoring

NASA Astrophysics Data System (ADS)

Han, Congzheng

2017-04-01

There has been significantly increasing recognition that millimeter waves from 30 GHz to 300 GHz as carriers for future 5G cellular networks. This is good for high speed, line-of-sight communication, potentially using very densely deployed infrastructure involving many small cells. High resolution, continuous and accurate monitoring of environmental conditions, such as rainfall and water vapor are of great important to meteorology, hydrology (e.g. flood warning), agriculture, environmental policy (e.g. pollution regulation) and weather forecasting. We have built a 28GHz measurement link at our research institute in central Beijing, China. This work will study the potential of using millimeter wave based wireless links to monitor environmental conditions including rainfall and water vapor.

Scannable Millimeter Wave Arrays. Volume 1

DTIC Science & Technology

1989-04-01

confusions all became clarified. In the process , much was learned of a basic nature, and the behavior of the microstrip leaky-wave strip antennas became... process , we can compute the complete propagation behavior for the structure in Fig. 3,10. We are interested in particular in the variation of 01ko...from conical scan. To understand the reason for the effect, let us reexamine the scan process . We first consider the limiting case for which k op = 0

Magnetic control of valley pseudospin in monolayer WSe 2

DOE PAGES

Aivazian, G.; Gong, Zhirui; Jones, Aaron M.; ...

2015-01-26

Local energy extrema of the bands in momentum space, or valleys, can endow electrons in solids with pseudo-spin in addition to real spin 1-5. In transition metal dichalcogenides this valley pseudo-spin, like real spin, is associated with a magnetic moment1,6 which underlies the valley-dependent circular dichroism 6 that allows optical generation of valley polarization 7-9, intervalley quantum coherence 10, and the valley Hall effect 11. However, magnetic manipulation of valley pseudospin via this magnetic moment 12-13, analogous to what is possible with real spin, has not been shown before. Here we report observation of the valley Zeeman splitting and magneticmore » tuning of polarization and coherence of the excitonic valley pseudospin, by performing polarization-resolved magneto-photoluminescence on monolayer WSe 2. Our measurements reveal both the atomic orbital and lattice contributions to the valley orbital magnetic moment; demonstrate the deviation of the band edges in the valleys from an exact massive Dirac fermion model; and reveal a striking difference between the magnetic responses of neutral and charged valley excitons which is explained by renormalization of the excitonic spectrum due to strong exchange interactions.« less

Spin and valley filter across line defect in silicene

NASA Astrophysics Data System (ADS)

Wang, Sake; Ren, Chongdan; Li, Yunfang; Tian, Hongyu; Lu, Weitao; Sun, Minglei

2018-05-01

We propose a new scheme to achieve an effective spin/valley filter in silicene with extended line defect on the basis of spin–valley coupling due to the intrinsic spin-orbit coupling (SOC). The transmission coefficient of the spin/valley states is seriously affected by the SOC. When a perpendicular magnetic field is applied on one side of the line defect, one valley state will experience backscattering, but the other valley will not; this leads to high valley polarization in all transmission directions. Moreover, the spin/valley polarization can be enhanced to 96% with the aid of a perpendicular electric field.

Formation of Valley Networks in a Cold and Icy Early Mars Climate: Predictions for Erosion Rates and Channel Morphology

NASA Astrophysics Data System (ADS)

Cassanelli, J.

2017-12-01

Mars is host to a diverse array of valley networks, systems of linear-to-sinuous depressions which are widely distributed across the surface and which exhibit branching patterns similar to the dendritic drainage patterns of terrestrial fluvial systems. Characteristics of the valley networks are indicative of an origin by fluvial activity, providing among the most compelling evidence for the past presence of flowing liquid water on the surface of Mars. Stratigraphic and crater age dating techniques suggest that the formation of the valley networks occurred predominantly during the early geologic history of Mars ( 3.7 Ga). However, whether the valley networks formed predominantly by rainfall in a relatively warm and wet early Mars climate, or by snowmelt and episodic rainfall in an ambient cold and icy climate, remains disputed. Understanding the formative environment of the valley networks will help distinguish between these warm and cold end-member early Mars climate models. Here we test a conceptual model for channel incision and evolution under cold and icy conditions with a substrate characterized by the presence of an ice-free dry active layer and subjacent ice-cemented regolith, similar to that found in the Antarctic McMurdo Dry Valleys. We implement numerical thermal models, quantitative erosion and transport estimates, and morphometric analyses in order to outline predictions for (1) the precise nature and structure of the substrate, (2) fluvial erosion/incision rates, and (3) channel morphology. Model predictions are compared against morphologic and morphometric observational data to evaluate consistency with the assumed cold climate scenario. In the cold climate scenario, the substrate is predicted to be characterized by a kilometers-thick globally-continuous cryosphere below a 50-100 meter thick desiccated ice-free zone. Initial results suggest that, with the predicted substrate structure, fluvial channel erosion and morphology in a cold early Mars

Fabrication of Tunnel Junctions For Direct Detector Arrays With Single-Electron Transistor Readout Using Electron-Beam Lithography

NASA Technical Reports Server (NTRS)

Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Rhee, K. W.; Teufel, J.; Schoelkopf, R. J.

2002-01-01

This paper will describe the fabrication of small aluminum tunnel junctions for applications in astronomy. Antenna-coupled superconducting tunnel junctions with integrated single-electron transistor readout have the potential for photon-counting sensitivity at sub-millimeter wavelengths. The junctions for the detector and single-electron transistor can be made with electron-beam lithography and a standard self-aligned double-angle deposition process. However, high yield and uniformity of the junctions is required for large-format detector arrays. This paper will describe how measurement and modification of the sensitivity ratio in the resist bilayer was used to greatly improve the reliability of forming devices with uniform, sub-micron size, low-leakage junctions.

Calibration, reconstruction, and rendering of cylindrical millimeter-wave image data

NASA Astrophysics Data System (ADS)

Sheen, David M.; Hall, Thomas E.

2011-05-01

Cylindrical millimeter-wave imaging systems and technology have been under development at the Pacific Northwest National Laboratory (PNNL) for several years. This technology has been commercialized, and systems are currently being deployed widely across the United States and internationally. These systems are effective at screening for concealed items of all types; however, new sensor designs, image reconstruction techniques, and image rendering algorithms could potentially improve performance. At PNNL, a number of specific techniques have been developed recently to improve cylindrical imaging methods including wideband techniques, combining data from full 360-degree scans, polarimetric imaging techniques, calibration methods, and 3-D data visualization techniques. Many of these techniques exploit the three-dimensionality of the cylindrical imaging technique by optimizing the depth resolution of the system and using this information to enhance detection. Other techniques, such as polarimetric methods, exploit scattering physics of the millimeter-wave interaction with concealed targets on the body. In this paper, calibration, reconstruction, and three-dimensional rendering techniques will be described that optimize the depth information in these images and the display of the images to the operator.

Optics for MUSIC: a new (sub)millimeter camera for the Caltech Submillimeter Observatory

NASA Astrophysics Data System (ADS)

Sayers, Jack; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran P.; Gao, Jiansong; Glenn, Jason; Golwala, Sunil R.; Hollister, Matt I.; LeDuc, Henry G.; Mazin, Benjamin A.; Maloney, Philip R.; Noroozian, Omid; Nguyen, Hien T.; Schlaerth, James A.; Siegel, Seth; Vaillancourt, John E.; Vayonakis, Anastasios; Wilson, Philip R.; Zmuidzinas, Jonas

2010-07-01

We will present the design and implementation, along with calculations and some measurements of the performance, of the room-temperature and cryogenic optics for MUSIC, a new (sub)millimeter camera we are developing for the Caltech Submm Observatory (CSO). The design consists of two focusing elements in addition to the CSO primary and secondary mirrors: a warm off-axis elliptical mirror and a cryogenic (4K) lens. These optics will provide a 14 arcmin field of view that is diffraction limited in all four of the MUSIC observing bands (2.00, 1.33, 1.02, and 0.86 mm). A cold (4K) Lyot stop will be used to define the primary mirror illumination, which will be maximized while keeping spillover at the sub 1% level. The MUSIC focal plane will be populated with broadband phased antenna arrays that efficiently couple to factor of (see manuscript) 3 in bandwidth,1, 2 and each pixel on the focal plane will be read out via a set of four lumped element filters that define the MUSIC observing bands (i.e., each pixel on the focal plane simultaneously observes in all four bands). Finally, a series of dielectric and metal-mesh low pass filters have been implemented to reduce the optical power load on the MUSIC cryogenic stages to a quasi-negligible level while maintaining good transmission in-band.

Contact Whiskers for Millimeter Wave Diodes

NASA Technical Reports Server (NTRS)

Kerr, A. R.; Grange, J. A.; Lichtenberger, J. A.

1978-01-01

Several techniques are investigated for making short conical tips on wires (whiskers) used for contacting millimeter-wave Schottky diodes. One procedure, using a phosphoric and chromic acid etching solution (PCE), is found to give good results on 12 microns phosphor-bronze wires. Full cone angles of 60 degrees-80 degrees are consistently obtained, compared with the 15 degrees-20 degrees angles obtained with the widely used sodium hydroxide etch. Methods are also described for cleaning, increasing the tip diameter (i.e. blunting), gold plating, and testing the contact resistance of the whiskers. The effects of the whisker tip shape on the electrical resistance, inductance, and capacitance of the whiskers are studied, and examples given for typical sets of parameters.

27 CFR 9.36 - McDowell Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

....” (b) Approved maps. The appropriate map for determining the boundaries of the McDowell Valley... and the ridge line (highest elevation line) between the McDowell Creek Valley and the Dooley Creek Valley. (3) Then southeasterly along the ridge line (highest elevation line) to the intersection of the...

27 CFR 9.36 - McDowell Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

....” (b) Approved maps. The appropriate map for determining the boundaries of the McDowell Valley... and the ridge line (highest elevation line) between the McDowell Creek Valley and the Dooley Creek Valley. (3) Then southeasterly along the ridge line (highest elevation line) to the intersection of the...

Valley Near Nilus Chaos

NASA Technical Reports Server (NTRS)

2003-01-01

MGS MOC Release No. MOC2-504, 5 October 2003

This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a valley near Nilus Chaos, around 25.2oN, 80.3oW. The scene has a uniform albedo, indicating that all of the landforms are probably mantled by fine, bright dust. Dark streaks on the valley walls indicate places where recent dust avalanches have occurred. The ripple-like dune features on the valley floor were formed by wind, but today they are inactive and covered with dust. A few craters, created by impacting debris, have formed on the dunes, again attesting to their inactivity in the modern martian environment. The image covers an area 3 km (1.9 mi) wide; it is illuminated by sunlight from the lower left.

Millimeter-wave Spectroscopy of NGC1068 With Z-Spec

NASA Astrophysics Data System (ADS)

Kamenetzky, Julia; Aguirre, J. E.; Bock, J. J.; Bradford, M.; Earle, L.; Glenn, J.; Maloney, P.; Matsuhara, H.; Naylor, B.; Nguyen, H. T.; Zmuidzinas, J.

2009-05-01

NGC1068 is commonly cited as the prototypical Seyfert 2 galaxy. Both the central and extended regions have been studied extensively across the electromagnetic spectrum, revealing many different astrophysical phenomena, such as a bright central region, radio jet knots, and a conical narrow-line region. Significantly, evidence has been found that the active galactic nucleus is shrouded by a dusty molecular disk, which could support the theory that viewing angle will unify Seyfert 1 and 2 galaxies. We observed NGC1068 with Z-Spec, a broadband (185-305 GHz) millimeter-wave grating spectrometer, at the Caltech Submillimeter Observatory. Its large bandwidth allows us to simultaneously observe multiple molecular rotational transitions along with the underlying continuum. The detector array is composed of 160 silicon-nitride micromesh bolometers cooled to 60 mK by an adiabatic demagnetization refrigerator (ADR) and a closed-cycle 3He refrigerator. Z-Spec's compact design is achieved via a WaFIRS (Waveguide Far IR Spectrometer) design utilizing a parallel-plate waveguide and curved diffraction grating. Z-Spec's spectral resolution is approximately 900 MHz at the band center. We obtained a high signal-to-noise ratio spectrum of NGC1068 in late January 2007. Key observable transitions in Z-Spec's bandpass include CO , 13CO, and C18O (J = 2 - 1), HCN, HNC, and HCO+ (J = 3 - 2), and multiple CS transitions. We are modeling the NGC1068 spectrum using these data and other transitions of these molecules from the literature to probe the physical characteristics of its interstellar medium, such as temperature, density, dense gas fraction, and the extent of the AGN's contribution to the molecular gas excitation. We will present preliminary results of the analysis.

27 CFR 9.194 - San Antonio Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

... significance. (b) Approved Maps. The appropriate maps for determining the boundary of the San Antonio Valley...) Hames Valley, California, 1949, photorevised 1978; (2) Tierra Redonda Mountain, California, 1949... southeast corner of section 14, T23S, R9E, on the Hames Valley map; (2) From the beginning point, proceed...

The millimeter wave super-Schottky diode detector

NASA Technical Reports Server (NTRS)

Silver, A. H.; Pedersen, R. J.; Mccoll, M.; Dickman, R. L.; Wilson, W. J.

1981-01-01

The 31 and 92 GHz measurements of the superconductor-Schottky diode extended to millimeter wavelengths by a redesign of the semiconductor interface are reported. Diodes were fabricated by pulse electroplating Pb on 2 x 10 to the 19th/cu cm p-Ga-As etched with HCl; a thin Au overplate is deposited to protect the Pb film from degradation and to improve its lifetime. The noise performance was almost ideal at 31 and 92 GHz; it was concluded that this diode is a quantum-limited-detector at 31 GHz, with excessive parasitic losses at 92 GHz.

A millimeter-wave tunneladder TWT

NASA Technical Reports Server (NTRS)

Wilson, D.

1988-01-01

A millimeter-wave traveling wave tube (TWT) was developed using a dispersive, high-impedance forward wave interaction structure based on a ladder, with non-space-harmonic interaction, for a tube with high gain per inch and high efficiency. The 'TunneLadder' interaction structure combines ladder properties modified to accommodate Pierce gun beam optics in a radially magnetized PM focusing structure. The development involved the fabrication of chemically milled, shaped ladders diffusion brazed to diamond cubes which are in turn active diffusion brazed to each ridge of a doubly ridged waveguide. Cold-test data, representing the (omega)(beta) and and impedance characteristics of the modified ladder circuit, were used in small and large-signal computer programs to predict TWT gain and efficiency. The structural design emphasizes ruggedness and reliability. Actual data from tested tubes verify the predicted performance while providing broader bandwidth than expected.

Millimeter-wave sensing of the environment: A bibliographic survey

NASA Technical Reports Server (NTRS)

Schneider, E.; Epstein, E. E.

1981-01-01

This literature survey was conducted to examine the field of millimeter wave remote sensing of the environment and collect all relevant observations made in the atmospheric windows near 90, 140, and 230 GHz of ocean, terrain, man-made features, and the atmosphere. Over 170 articles and reports were examined; bibliographic references are provided for all and abstracts are quoted when available. Selected highlights were extracted from the pertinent articles.

The Central Valley Hydrologic Model

NASA Astrophysics Data System (ADS)

Faunt, C.; Belitz, K.; Hanson, R. T.

2009-12-01

Historically, California’s Central Valley has been one of the most productive agricultural regions in the world. The Central Valley also is rapidly becoming an important area for California’s expanding urban population. In response to this competition for water, a number of water-related issues have gained prominence: conjunctive use, artificial recharge, hydrologic implications of land-use change, subsidence, and effects of climate variability. To provide information to stakeholders addressing these issues, the USGS made a detailed assessment of the Central Valley aquifer system that includes the present status of water resources and how these resources have changed over time. The principal product of this assessment is a tool, referred to as the Central Valley Hydrologic Model (CVHM), that simulates surface-water flows, groundwater flows, and land subsidence in response to stresses from human uses and from climate variability throughout the entire Central Valley. The CVHM utilizes MODFLOW combined with a new tool called “Farm Process” to simulate groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis. This model was discretized horizontally into 20,000 1-mi2 cells and vertically into 10 layers ranging in thickness from 50 feet at the land surface to 750 feet at depth. A texture model constructed by using data from more than 8,500 drillers’ logs was used to estimate hydraulic properties. Unmetered pumpage and surface-water deliveries for 21 water-balance regions were simulated with the Farm Process. Model results indicate that human activities, predominately surface-water deliveries and groundwater pumping for irrigated agriculture, have dramatically influenced the hydrology of the Central Valley. These human activities have increased flow though the aquifer system by about a factor of six compared to pre-development conditions. The simulated hydrology reflects spatial

Wintertime Ambient Ammonia Concentrations in Northern Utah's Urban Valleys

NASA Astrophysics Data System (ADS)

Hammond, I. A.; Martin, R. S.; Silva, P.; Baasandorj, M.

2017-12-01

Many of the population centers in northern Utah are currently classified as non-attainment or serious non-attainment, Wasatch Front, for PM2.5 and previous studies have shown ammonium nitrate to often be the largest contributor to the particulate mass. Furthermore, measurements have shown several of the Wasatch Front cities and Cache Valley (UT/ID) consistently recorded some of the highest ambient ammonia (NH3) concentrations in the continental United States. As a part of the multi-organization 2017 Utah Winter Fine Particulate Study real-time NH3 concentrations were monitored in the Cache Valley at the Logan, UT site, collocated at an EPA sampling trailer near the Utah State University (USU) campus. A Picarro model G2508 was to used collect 5-sec averaged concentrations of NH3, carbon dioxide (CO2), and methane (CH4) from January 16th to February 14th, 2017. Parts of three inversion events, wherein the PM2.5 concentrations approached or exceeded the National Ambient Air Quality Standards, were captured during the sampling period, including a 10-day event from January 25th to February 4th. Concentrations of all three of the observed species showed significant accumulation during the events, with NH3 concentrations ranging from below the detection limit (<0.5 ppb) to >70 ppb. Preliminary analysis suggested the temporal NH3 changes tracked the increase in PM2.5 throughout the inversion events; however, a one-day period of NH3 depletion during the main inversion event was observed while PM2.5 continued to increase. Additionally, a network of passive NH3 samplers (Ogawa Model 3300) were arrayed at 25 sites throughout the Cache Valley and at 11 sites located along the Wasatch Front. These networks sampled for three 7-day periods, during the same study time frame. Ion chromatographic (IC) analyses of the sample pads are not yet finalized; however, preliminary results show concentrations in the tens of ppb and seemingly spatially correlate with previous studies showing

NV PFA - Steptoe Valley

DOE Data Explorer

Jim Faulds

2015-10-29

All datasets and products specific to the Steptoe Valley model area. Includes a packed ArcMap project (.mpk), individually zipped shapefiles, and a file geodatabase for the northern Steptoe Valley area; a GeoSoft Oasis montaj project containing GM-SYS 2D gravity profiles along the trace of our seismic reflection lines; a 3D model in EarthVision; spreadsheet of links to published maps; and spreadsheets of well data.

27 CFR 9.27 - Lime Kiln Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Lime Kiln Valley. 9.27... OF THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.27 Lime Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley...

‘Valley Pearl’ table grape

USDA-ARS?s Scientific Manuscript database

‘Valley Pearl’ is an early to mid-season, white seedless table grape (Vitis vinifera L.) suitable for commercial table grape production where V. vinifera can be grown. Significant characteristics of ‘Valley Pearl’ are its high and consistent fruit production on spur pruned vines and large round berr...

Extraction of Martian valley networks from digital topography

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Collier, M. L.

2004-01-01

We have developed a novel method for delineating valley networks on Mars. The valleys are inferred from digital topography by an autonomous computer algorithm as drainage networks, instead of being manually mapped from images. Individual drainage basins are precisely defined and reconstructed to restore flow continuity disrupted by craters. Drainage networks are extracted from their underlying basins using the contributing area threshold method. We demonstrate that such drainage networks coincide with mapped valley networks verifying that valley networks are indeed drainage systems. Our procedure is capable of delineating and analyzing valley networks with unparalleled speed and consistency. We have applied this method to 28 Noachian locations on Mars exhibiting prominent valley networks. All extracted networks have a planar morphology similar to that of terrestrial river networks. They are characterized by a drainage density of approx.0.1/km, low in comparison to the drainage density of terrestrial river networks. Slopes of "streams" in Martian valley networks decrease downstream at a slower rate than slopes of streams in terrestrial river networks. This analysis, based on a sizable data set of valley networks, reveals that although valley networks have some features pointing to their origin by precipitation-fed runoff erosion, their quantitative characteristics suggest that precipitation intensity and/or longevity of past pluvial climate were inadequate to develop mature drainage basins on Mars.

Dynamics of Katabatic Winds in Colorado' Brush Creek Valley.

NASA Astrophysics Data System (ADS)

Vergeiner, I.; Dreiseitl, E.; Whiteman, C. David

1987-01-01

A method is proposed to evaluate the coupled mass, momentum and thermal energy budget equations for a deep valley under two-dimensional, steady-state flow conditions. The method requires the temperature, down- valley wind and valley width fields to be approximated by simple analytical functions. The vertical velocity field is calculated using the mass continuity equation. Advection terms in the momentum and energy equations are then calculated using finite differences computed on a vertical two-dimensional grid that runs down the valley's axis. The pressure gradient term in the momentum equation is calculated from the temperature field by means of the hydrostatic equation. The friction term is then calculated as a residual in the xmomentum equation, and the diabatic cooling term is calculated as a residual in the thermal energy budget equation.The method is applied to data from an 8-km-long segment of Colorado's; Brush Creek Valley on the night of 30-31 July 1982. Pressure decreased with distance down the peak on horizontal surfaces, with peak horizontal pressure gradients of 0.04 hPa km1. The valley mass budget indicated that subsidence was required in the valley to support calculated mean along-valley mass flux divergence. Peak subsidence rates on the order of 0.10 m s1 were calculated. Subsiding motions in the valley produced negative vertical down-valley momentum fluxes in the upper valley atmosphere, but produced positive down-valley momentum fluxes below the level of the jet. Friction, calculated as a residual in the x momentum equation, was negative, as expected on physical grounds. and attained reasonable quantitative values.The strong subsidence field in the stable valley atmosphere produced subsidence warming that was only partly counteracted by down-valley cold air advection. Strong diabatic cooling was therefore required in order to account for the weak net cooling of the valley atmosphere during the nighttime period when tethered balloon observations

Experimental validation of a millimeter wave radar technique to remotely sense atmospheric pressure at the Earth's surface

NASA Technical Reports Server (NTRS)

Flower, D. A.; Peckham, G. E.; Bradford, W. J.

1984-01-01

Experiments with a millimeter wave radar operating on the NASA CV-990 aircraft which validate the technique for remotely sensing atmospheric pressure at the Earth's surface are described. Measurements show that the precise millimeter wave observations needed to deduce pressure from space with an accuracy of 1 mb are possible, that sea surface reflection properties agree with theory and that the measured variation of differential absorption with altitude corresponds to that expected from spectroscopic models.

Conformal and Spectrally Agile Ultra Wideband Phased Array Antenna for Communication and Sensing

NASA Technical Reports Server (NTRS)

Novak, M.; Alwan, Elias; Miranda, Felix; Volakis, John

2015-01-01

There is a continuing need for reducing size and weight of satellite systems, and is also strong interest to increase the functional role of small- and nano-satellites (for instance SmallSats and CubeSats). To this end, a family of arrays is presented, demonstrating ultra-wideband operation across the numerous satellite communications and sensing frequencies up to the Ku-, Ka-, and Millimeter-Wave bands. An example design is demonstrated to operate from 3.5-18.5 GHz with VSWR2 at broadside, and validated through fabrication of an 8 x 8 prototype. This design is optimized for low cost, using Printed Circuit Board (PCB) fabrication. With the same fabrication technology, scaling is shown to be feasible up to a 9-49 GHz band. Further designs are discussed, which extend this wideband operation beyond the Ka-band, for instance from 20-80 GHz. Finally we will discuss recent efforts in the direct integration of such arrays with digital beamforming back-ends. It will be shown that using a novel on-site coding architecture, orders of magnitude reduction in hardware size, power, and cost is accomplished in this transceiver.

System using a megawatt class millimeter wave source and a high-power rectenna to beam power to a suspended platform

DOEpatents

Caplan, Malcolm; Friedman, Herbert W.

2005-07-19

A system for beaming power to a high altitude platform is based upon a high power millimeter gyrotron source, optical transmission components, and a high-power receiving antenna (i.e., a rectenna) capable of rectifying received millimeter energy and converting such energy into useable electrical power.

Millimeter-wave spectroscopy of hydantoin, a possible precursor of glycine

NASA Astrophysics Data System (ADS)

Ozeki, Hiroyuki; Miyahara, Rio; Ihara, Hiroto; Todaka, Satoshi; Kobayashi, Kaori; Ohishi, Masatoshi

2017-04-01

Context. Hydantoin (Imidazolidine-2, 4-dione, C3H4N2O2) is a five-membered heterocyclic compound that is known to arise from prebiotic molecules such as glycolic acid and urea, and to give the simplest amino acid, glycine, by hydrolysis under acidic condition. The gas chromatography combined with the mass spectrometry of carbonaceous chondrites lead to the detection of this molecule as well as several kinds of amino acids. Aims: The lack of spectroscopic information, especially on the rotational constants, has prevented us from conducting a search for hydantoin in interstellar space. If a rotational temperature of 100 K is assumed as the kinetic temperature of a star-forming region, the spectral intensity is expected to be at its maximum in the millimeter-wave region. Laboratory spectroscopy of hydantoin in the millimeter-wave region is the most important in providing accurate rest frequencies to be used for astronomical research. Methods: Pure rotational spectra of hydantoin were observed in the millimeter-wave region using the frequency modulated microwave spectrometer at Toho University. Solid hydantoin was heated to around 150 °C to provide appropriate vapor pressure. Quantum chemical calculations suggest that the permanent dipole moment of this molecule lies almost along the b-molecular axis, so that spectral search for b-type R-branch transition has been conducted. Results: Rotational and centrifugal distortion constants up to the fourth order for the ground vibrational state of hydantoin were accurately determined by measuring 161 b-type transitions in the frequency range between 90 and 370 GHz. In addition, we succeeded in assigning 230 satellite lines, which were attributed to the two vibrationally excited states. The spectral intensity ratio of these lines indicates that these states correspond to the low-lying (approximately 150 cm-1 above the ground state) vibrational modes. Conclusions: The frequency catalog of hydantoin in the millimeter-wave range

Geophysical character of the intraplate Wabash Fault System from the Wabash EarthScope FlexArray

NASA Astrophysics Data System (ADS)

Conder, J. A.; Zhu, L.; Wood, J. D.

2017-12-01

The Wabash Seismic Array was an EarthScope funded FlexArray deployment across the Wabash Fault System. The Wabash system is long known for oil and gas production. The fault system is often characterized as an intraplate seismic zone as it has produced several earthquakes above M4 in the last 50 years and potentially several above M7 in the Holocene. While earthquakes are far less numerous in the Wabash system than in the nearby New Madrid seismic zone, the seismic moment is nearly twice that of New Madrid over the past 50 years. The array consisted of 45 broadband instruments deployed across the axis to study the larger structure and 3 smaller phased arrays of 9 short-period instruments each to get a better sense of the local seismic output of smaller events. First results from the northern phased array indicate that seismicity in the Wabash behaves markedly differently than in New Madrid, with a low b-value around 0.7. Receiver functions show a 50 km thick crust beneath the system, thickening somewhat to the west. A variable-depth, positive-amplitude conversion in the deep crust gives evidence for a rift pillow at the base of the system within a dense lowermost crustal layer. Low Vs and a moderate negative amplitude conversion in the mid crust suggest a possible weak zone that could localize deformation. Shear wave splitting shows fast directions consistent with absolute plate motion across the system. Split times drop in magnitude to 0.5-0.7 seconds within the valley while in the 1-1.5 second range outside the valley. This magnitude decrease suggests a change in mantle signature beneath the fault system, possibly resulting from a small degree of local flow in the asthenosphere either along axis (as may occur with a thinned lithosphere) or by vertical flow (e.g., from delamination or dripping). We are building a 2D tomographic model across the region, relying primarily on teleseismic body waves. The tomography will undoubtedly show variations in crustal structure

Fretted Terrain Valley in Coloe Fossae Region

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Figure 1 Click on image for larger version

The image in figure 1 shows lineated valley fill in one of a series of enclosed, intersecting troughs known as Coloe (Choloe) Fossae. Lineated valley fill consists of rows of material in valley centers that are parallel to the valley walls. It is probably made of ice-rich material and boulders that are left behind when the ice-rich material sublimates. Very distinct rows can be seen near the south (bottom) wall of the valley. Lineated valley fill is thought to result from mass wasting (downslope movement) of ice-rich material from valley walls towards their centers. It is commonly found in valleys near the crustal dichotomy that separates the two hemispheres of Mars. The valley shown here joins four other valleys with lineated fill near the top left corner of this image. Their juncture is a topographic low, suggesting that the lineated valley fill from the different valleys may be flowing or creeping towards the low area (movement towards the upper left of the image). The valley walls appear smooth at first glance but are seen to be speckled with small craters several meters in diameter at HiRISE resolution (see contrast-enhanced subimage). This indicates that at least some of the wall material has been stable to mass wasting for some period of time. Also seen on the valley wall are elongated features shaped like teardrops. These are most likely slightly older craters that have been degraded due to potentially recent downhill creep. It is unknown whether the valley walls are shedding material today. The subimage is approximately 140 x 400 m (450 x 1280 ft).

Image PSP_001372_2160 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 11, 2006. The complete image is centered at 35.5 degrees latitude, 56.8 degrees East longitude. The range to the target site was 290.3 km (181

Victor Valley College Agreement between the Victor Valley Community College District and the Victor Valley College California Teachers Association Chapter 1170. July 1989 - June 1992.

ERIC Educational Resources Information Center

Victor Valley Community Coll. District, Victorville, CA.

The collective bargaining agreement between the Victor Valley College Board of Trustees and the Victor Valley College California Teachers Association/National Education Association is presented. This contract, covering the period from July 1989 through June 1992, deals with the following topics: bargaining agent recognition; district and…

Valley spin polarization of Tl/Si(111)

NASA Astrophysics Data System (ADS)

Stolwijk, Sebastian D.; Schmidt, Anke B.; Sakamoto, Kazuyuki; Krüger, Peter; Donath, Markus

2017-11-01

The metal/semiconductor hybrid system Tl/Si(111)-(1 ×1 ) exhibits a unique Tl-derived surface state with remarkable properties. It lies within the silicon band gap and forms spin-momentum-locked valleys close to the Fermi energy at the K ¯ and K¯' points. These valleys are completely spin polarized with opposite spin orientation at K ¯ and K¯' and show a giant spin splitting of more than 0.5 eV. We present a detailed preparation study of the surface system and demonstrate that the electronic valleys are extremely robust, surviving exposure to 100 L hydrogen and 500 L oxygen. We investigate the influence of additional Tl atoms on the spin-polarized valleys. By combining photoemission and inverse photoemission, we prove the existence of fully spin-polarized valleys crossing the Fermi level. Moreover, these metallic valleys carry opposite Berry curvature at K ¯ and K¯', very similar to WSe2, promising a large spin Hall effect. Thus, Tl/Si(111)-(1 ×1 ) possesses all necessary key properties for spintronic applications.

Electrical valley filtering in transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Hsieh, Tzu-Chi; Chou, Mei-Yin; Wu, Yu-Shu

2018-03-01

This work investigates the feasibility of electrical valley filtering for holes in transition metal dichalcogenides. We look specifically into the scheme that utilizes a potential barrier to produce valley-dependent tunneling rates, and perform the study with both a k .p -based analytic method and a recursive Green's function-based numerical method. The study yields the transmission coefficient as a function of incident energy and transverse wave vector, for holes going through lateral quantum barriers oriented in either armchair or zigzag directions, in both homogeneous and heterogeneous systems. The main findings are the following: (1) The tunneling current valley polarization increases with increasing barrier width or height; (2) both the valley-orbit interaction and band structure warping contribute to valley-dependent tunneling, with the former contribution being manifest in structures with asymmetric potential barriers, and the latter being orientation dependent and reaching maximum for transmission in the armchair direction; and (3) for transmission ˜0.1 , a tunneling current valley polarization of the order of 10 % can be achieved.

Observation of valley-dependent beams in photonic graphene.

PubMed

Deng, Fusheng; Sun, Yong; Wang, Xiao; Xue, Rui; Li, Yuan; Jiang, Haitao; Shi, Yunlong; Chang, Kai; Chen, Hong

2014-09-22

Valley-dependent propagation of light in an artificial photonic hexagonal lattice, akin to electrons in graphene, is investigated in microwave regime. Both numerical and experimental results show that the valley degeneracy in the photonic graphene is broken when the frequency is away from the Dirac point. The peculiar anisotropic wave transport property due to distinct valleys is analyzed using the equifrequency contours. More interestingly, the valley-dependent self-collimation and beam splitting phenomena are experimentally demonstrated with the armchair and zigzag interfaces, respectively. Our results confirm that there are two inequivalent Dirac points that lead to two distinct valleys in photonic graphene, which could be used to control the flow of light and might be used to carry information in valley polarized beam splitter, collimator or guiding device.

27 CFR 9.58 - Carmel Valley.

Code of Federal Regulations, 2011 CFR

2011-04-01

....” (b) Approved maps. The approved maps for determining the boundary of the Carmel Valley viticultural... Ridge, Calif., dated 1956; and (5) Rana Creek, Calif., dated 1956. (c) Boundary. The Carmel Valley...

27 CFR 9.58 - Carmel Valley.

Code of Federal Regulations, 2010 CFR

2010-04-01

....” (b) Approved maps. The approved maps for determining the boundary of the Carmel Valley viticultural... Ridge, Calif., dated 1956; and (5) Rana Creek, Calif., dated 1956. (c) Boundary. The Carmel Valley...

Water resources of Parowan Valley, Iron County, Utah

USGS Publications Warehouse

Marston, Thomas M.

2017-08-29

Parowan Valley, in Iron County, Utah, covers about 160 square miles west of the Red Cliffs and includes the towns of Parowan, Paragonah, and Summit. The valley is a structural depression formed by northwest-trending faults and is, essentially, a closed surface-water basin although a small part of the valley at the southwestern end drains into the adjacent Cedar Valley. Groundwater occurs in and has been developed mainly from the unconsolidated basin-fill aquifer. Long-term downward trends in groundwater levels have been documented by the U.S. Geological Survey (USGS) since the mid-1950s. The water resources of Parowan Valley were assessed during 2012 to 2014 with an emphasis on refining the understanding of the groundwater and surface-water systems and updating the groundwater budget.Surface-water discharge of five perennial mountain streams that enter Parowan Valley was measured from 2013 to 2014. The total annual surface-water discharge of the five streams during 2013 to 2014 was about 18,000 acre-feet (acre-ft) compared to the average annual streamflow of about 22,000 acre-ft from USGS streamgages operated on the three largest of these streams from the 1940s to the 1980s. The largest stream, Parowan Creek, contributes more than 50 percent of the annual surface-water discharge to the valley, with smaller amounts contributed by Red, Summit, Little, and Cottonwood Creeks.Average annual recharge to the Parowan Valley groundwater system was estimated to be about 25,000 acre-ft from 1994 to 2013. Nearly all recharge occurs as direct infiltration of snowmelt and rainfall on the Markagunt Plateau east of the valley. Smaller amounts of recharge occur as infiltration of streamflow and unconsumed irrigation water near the east side of the valley on alluvial fans associated with mountain streams at the foot of the Red Cliffs. Subsurface flow from the mountain block to the east of the valley is a significant source of groundwater recharge to the basin-fill aquifer

Estimates of evapotranspiration in alkaline scrub and meadow communities of Owens Valley, California, using the Bowen-ratio, eddy-correlation, and penman-combination methods

USGS Publications Warehouse

Duell, Lowell F. W.

1990-01-01

In Owens Valley, evapotranspiration (ET) is one of the largest components of outflow in the hydrologic budget and the least understood. ET estimates for December 1983 through October 1985 were made for seven representative locations selected on the basis of geohydrology and the characteristics of phreatophytic alkaline scrub and meadow communities. The Bowen-ratio, eddy-correlation, and Penman-combination methods were used to estimate ET. The results of the analyses appear satisfactory when compared with other estimates of ET. Results by the eddy-correlation method are for a direct and a residual latent-heat flux that is based on sensible-heat flux and energy-budget measurements. Penman-combination potential-ET estimates were determined to be unusable because they overestimated actual ET. Modification of the psychrometer constant of this method to account for differences between heat-diffusion resistance and vapor-diffusion resistance permitted actual ET to be estimated. The methods described in this report may be used for studies in similar semiarid and arid rangeland areas in the Western United States. Meteorological data for three field sites are included in the appendix of this report. Simple linear regression analysis indicates that ET estimates are correlated to air temperature, vapor-density deficit, and net radiation. Estimates of annual ET range from 301 millimeters at a low-density scrub site to 1,137 millimeters at a high-density meadow site. The monthly percentage of annual ET was determined to be similar for all sites studied.

Optical manipulation of valley pseduospin in 2D semiconductors

NASA Astrophysics Data System (ADS)

Ye, Ziliang

Valley polarization associated with the occupancy in the energy degenerate but quantum mechanically distinct valleys in the momentum space closely resembles spin polarization and has been proposed as a pseudospin carrier for future quantum information technologies. Monolayers of transition metal dichalcogenide (TMDC) crystals, with broken inversion symmetry and large spin-orbital coupling, support robust valley polarization and therefore provide an important platform for studying valley-dependent physics. Besides optical excitation and photoluminescence detection, valley polarization has been electrically measured through the valley Hall effect and created through spin injection from ferromagnetic semiconductor contacts. Moreover, the energy degeneracy of the valley degree of freedom has been lifted by the optical Stark effect. Recently, we have demonstrated optical manipulation of valley coherence, i.e., of the valley pseudospin, by the optical Stark effect in monolayer WSe2. Using below-bandgap circularly polarized light, we rotated the valley pseudospin on the femtosecond time scale. Both the direction and speed of the rotation can be optically controlled by tuning the dynamic phase of excitons in opposite valleys. The pseudospin rotation was identified by changes in the polarization of the photoluminescence. In addition, by varying the time delay between the excitation and control pulses, we directly probed the lifetime of the intervalley coherence. Similar rotation levels have also been observed in static magneto-optic experiments. Our work presents an important step towards the full control of the valley degree of freedom in 2D semiconductors. The work was done in collaboration with Dr. Dezheng Sun and Prof. Tony F. Heinz.