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Sample records for bandpass butterworth filter

  1. Colloidal Bandpass and Bandgap Filters

    NASA Astrophysics Data System (ADS)

    Yellen, Benjamin; Tahir, Mukarram; Ouyang, Yuyu; Nori, Franco

    2013-03-01

    Thermally or deterministically-driven transport of objects through asymmetric potential energy landscapes (ratchet-based motion) is of considerable interest as models for biological transport and as methods for controlling the flow of information, material, and energy. Here, we provide a general framework for implementing a colloidal bandpass filter, in which particles of a specific size range can be selectively transported through a periodic lattice, whereas larger or smaller particles are dynamically trapped in closed-orbits. Our approach is based on quasi-static (adiabatic) transition in a tunable potential energy landscape composed of a multi-frequency magnetic field input signal with the static field of a spatially-periodic magnetization. By tuning the phase shifts between the input signal and the relative forcing coefficients, large-sized particles may experience no local energy barriers, medium-sized particles experience only one local energy barrier, and small-sized particles experience two local energy barriers. The odd symmetry present in this system can be used to nudge the medium-sized particles along an open pathway, whereas the large or small beads remain trapped in a closed-orbit, leading to a bandpass filter, and vice versa for a bandgap filter. NSF CMMI - 0800173, Youth 100 Scholars Fund

  2. Divergence-tolerant resonant bandpass filters.

    PubMed

    Ko, Yeong Hwan; Niraula, Manoj; Magnusson, Robert

    2016-07-15

    Bandpass filters based on subwavelength dielectric gratings are grounded in physical principles that are totally distinct from their thin-film counterparts. Ease in fabrication, design scalability, material sparsity, and on-chip integration compatibility makes them a promising alternative especially for long-wavelength applications. Here we demonstrate the interesting attribute of resonant bandpass filters of high angular stability for fully conical light incidence. Fashioning an experimental bandpass filter with a subwavelength silicon grating on a quartz substrate, we show that fully conical incidence provides an angular full width at half-maximum linewidth of ∼9.5° compared to a linewidth of ∼0.1° for classical incidence. Slow angular variation of the central wavelength with full conical incidence arises via a corresponding slow angular variation of the resonant second diffraction orders driving the pertinent leaky modes. Moreover, full conical incidence maintains a profile with a single passband as opposed to the formation of two passbands characteristic of resonant subwavelength gratings under classical incidence. Our experimental results demonstrate excellent stability in angle, spectral profile, linewidth, and efficiency. PMID:27420521

  3. Narrow bandpass cryogenic filter for microwave measurements.

    PubMed

    Ivanov, B I; Klimenko, D N; Sultanov, A N; Il'ichev, E; Meyer, H-G

    2013-05-01

    An ultra-wide stopband hairpin bandpass filter with integrated nonuniform transmission lines was designed and fabricated for highly sensitive measurements at cryogenic temperatures down to millikelvin and a frequency range of 10 Hz-10 GHz. The scattering matrices of the filter were characterized at T = 4.2 K. The filter provides a stopband from 10 Hz to 2.2 GHz and from 2.3 GHz to 10 GHz with more than 50 dB and 40 dB of amplitude suppression, respectively. The center frequency of the passband is f0 = 2.25 GHz with a bandwidth Δf = 80 MHz. The maximum insertion loss in the passband is 4 dB. The filter has a 50 Ω input and output impedance, SubMiniature version A connector termination, and significantly reduced form factor. The wide stopband frequency range and narrow passband in conjunction with small dimensions make the filter suitable to use it as a part of a high sensitive readout for superconducting quantum circuits, such as superconducting quantum bits and cryogenic parametric amplifiers. PMID:23742575

  4. Narrow bandpass cryogenic filter for microwave measurements

    NASA Astrophysics Data System (ADS)

    Ivanov, B. I.; Klimenko, D. N.; Sultanov, A. N.; Il'ichev, E.; Meyer, H.-G.

    2013-05-01

    An ultra-wide stopband hairpin bandpass filter with integrated nonuniform transmission lines was designed and fabricated for highly sensitive measurements at cryogenic temperatures down to millikelvin and a frequency range of 10 Hz-10 GHz. The scattering matrices of the filter were characterized at T = 4.2 K. The filter provides a stopband from 10 Hz to 2.2 GHz and from 2.3 GHz to 10 GHz with more than 50 dB and 40 dB of amplitude suppression, respectively. The center frequency of the passband is f0 = 2.25 GHz with a bandwidth Δf = 80 MHz. The maximum insertion loss in the passband is 4 dB. The filter has a 50 Ω input and output impedance, SubMiniature version A connector termination, and significantly reduced form factor. The wide stopband frequency range and narrow passband in conjunction with small dimensions make the filter suitable to use it as a part of a high sensitive readout for superconducting quantum circuits, such as superconducting quantum bits and cryogenic parametric amplifiers.

  5. Improving holographic reconstruction by automatic Butterworth filtering for microelectromechanical systems characterization.

    PubMed

    Matrecano, Marcella; Memmolo, Pasquale; Miccio, Lisa; Persano, Anna; Quaranta, Fabio; Siciliano, Pietro; Ferraro, Pietro

    2015-04-10

    Digital holographic microscopy is an important interferometric tool in optical metrology allowing the investigation of engineered surfaces with microscale lateral resolution and nanoscale axial precision. In particular, microelectromechanical systems (MEMS) surface analysis, conducted by holographic characterization, requires high accuracy for functional testing. The main issues related to MEMS inspection are the superficial roughness and the complex geometry resulting from the several fabrication steps. Here, an automatic procedure, particularly suited in the case of high-roughness surfaces, is presented to selectively filter the spectrum, providing very low-noise reconstructed images. The numerical procedure is based on Butterworth filtering, and the obtained results demonstrate a significant increase in the images' quality and in the accuracy of the measurements, making our technique highly applicable for quantitative phase imaging in MEMS analysis. Furthermore, our method is fully tunable to the spectrum under investigation and automatic. This makes it highly suitable for real-time applications. Several experimental tests show the suitability of the proposed approach. PMID:25967334

  6. Photonic microwave bandpass filter with improved dynamic range.

    PubMed

    Yan, Yu; Yao, Jianping

    2008-08-01

    A technique to improve the dynamic range of a photonic microwave bandpass filter is proposed and experimentally demonstrated. The filter is implemented based on phase modulation to intensity modulation conversion using fiber Bragg gratings (FBGs) serving as frequency discriminators, with the optical carriers located at the left or right slopes of the FBGs, to generate positive or negative tap coefficients. The dynamic range of the photonic microwave bandpass filter is increased by reducing the optical-carrier-induced shot noise and relative intensity noise at the photodetector, which is realized by placing the optical carriers at the lower slopes of the FBG reflection spectra. A photonic microwave bandpass filter with an improvement in dynamic range of about 10 dB is demonstrated. PMID:18670527

  7. Cryogenic metal mesh bandpass filters for submillimeter astronomy

    NASA Technical Reports Server (NTRS)

    Dragovan, M.

    1984-01-01

    The design and performance of a tunable double-half-wave bandpass filter centered at 286 microns (Delta lambda/lambda = 0.16) and operating at cryogenic temperatures (for astronomy applications) are presented. The operating principle is explained, and the fabrication of the device, which comprises two identical mutually coupled Fabry-Perot filters with electroformed Ni-mesh reflectors and is tuned by means of variable spacers, is described. A drawing of the design and graphs of computed and measured performance are provided. Significantly improved bandpass characteristics are obtained relative to the single Fabry-Perot filter.

  8. A compact triple-band bandpass filter based on metamaterials

    NASA Astrophysics Data System (ADS)

    Zhao, Ya-juan; Jiang, Bo; Li, Bao-yi; Wang, Dong-hong

    2016-07-01

    This paper presents a compact triple-band bandpass filter based on metamaterials. The miniaturization is realized by the principle of phase compensation of metamaterial. Compared with the conventional half-wavelength filter, the metamaterial filter has a small size of 10 mm×10 mm. The triple-band bandpass filter performance has been validated by the electromagnetic simulation software of high frequency structure simulator (HFSS). The results illustrate that the filter is designed with center frequencies of 2.4 GHz, 5.1 GHz and 8.8 GHz, bandwidths of about 7.9% (2.31—2.50 GHz), 7.8% (5.0—5.4 GHz) and 7.4% (8.50—9.15 GHz), respectively, and it shows good band pass characteristics.

  9. Thermoluminescence dosimeters with narrow bandpass filters

    SciTech Connect

    Walker, Scottie W.

    2004-07-20

    A dosimetry method exposes more than one thermoluminescence crystals to radiation without using conventional filters, and reads the energy stored in the crystals by converting the energy to light in a conventional manner, and then filters each crystal output in a different portion of the spectrum generated by the crystals.

  10. Spectral performance of WFIRST/AFTA bandpass filter prototypes

    NASA Astrophysics Data System (ADS)

    Quijada, Manuel A.; Huang, Winson; Miller, Kevin H.; Seide, Laurie; Content, David; Kruk, Jeffrey

    2015-09-01

    The current baseline for the Wide-Field Infrared Survey Telescope Astrophysics Focused Telescope Assets (WFIRST/AFTA) instrument includes a single wide-field channel instrument for both imaging and spectroscopy. The only routinely moving part during scientific observations for this wide-field channel is the element wheel (EW) assembly. This filter-wheel assembly will have 8 positions that will be populated with 6 bandpass filters, a blank position, and a grism assembly that will consist of a three-element assembly to disperse the central wavelength undeviated for galaxy redshift surveys. All elements in the EW assembly will be made out of fused silica substrates (110 mm diameter) that will have the appropriate bandpass coatings according to the filter designations (Z087, Y106, J129, H158, F184, W149 and Grism). This paper will present and discuss spectral performance (including spectral transmission and surface-figure wavefront errors ) for a subset of the bandpass filter complement that include filters such as Z087, W149, and Grism. These filter coatings have been procured from three different vendors to assess the most challenging aspects in terms of the in-band throughput (> 95 %), out of band rejection (< 10-4), spatial uniformity (< 1% transmission level) and the cut-on and cut-off slopes (≍ 3% for the filters and 0.3% for the grism coatings).

  11. Compact Micromachined Infrared Bandpass Filters for Planetary Spectroscopy

    NASA Technical Reports Server (NTRS)

    Merrell, Willie C., II; Aslam, Shahid; Brown, Ari D.; Chervenak, James A.; Huang, Wei-Chung; Quijada, Manuel; Wollack, Edward

    2011-01-01

    The future needs of space based observational planetary and astronomy missions include low mass and small volume radiometric instruments that can operate in high radiation and low temperature environments. Here we focus on a central spectroscopic component, the bandpass filter. We model the bandpass response of the filters to target the wavelength of the resonance peaks at 20, 40, and 60 micrometers and report good agreement between the modeled and measured response. We present a technique of using common micromachining processes for semiconductor fabrication to make compact, free standing resonant metal mesh filter arrays with silicon support frames. The process can accommodate multiple detector array architectures and the silicon frame provides lightweight mechanical support with low form factor. We also present a conceptual hybridization of the filters with a detector array.

  12. Switched Band-Pass Filters for Adaptive Transceivers

    NASA Technical Reports Server (NTRS)

    Wang, Ray

    2007-01-01

    Switched band-pass filters are key components of proposed adaptive, software- defined radio transceivers that would be parts of envisioned digital-data-communication networks that would enable real-time acquisition and monitoring of data from geographically distributed sensors. Examples of sensors to be connected to such networks include security cameras, radio-frequency identification units, and geolocation units based on the Global Positioning System. Through suitable software configuration and without changing hardware, these transceivers could be made to operate according to any of a number of complex wireless-communication standards that could be characterized by diverse modulation schemes, bandwidths, and data-handling protocols. The adaptive transceivers would include field-programmable gate arrays (FPGAs) and digital signal-processing hardware. In the receiving path of a transceiver, the incoming signal would be amplified by a low-noise amplifier (LNA). The output spectrum of the LNA would be processed by a band-pass filter operating in the frequency range between 900 MHz and 2.4 GHz. Then a down-converter would translate the signal to a lower frequency range to facilitate analog-to-digital conversion, which would be followed by baseband processing by one or more FPGAs. In the transmitting path, a digital stream would first be converted to an analog signal, which would then be up-converted to a selected frequency band before being applied to a transmitting power amplifier. The aforementioned band-pass filter in the receiving path would be a combination of resonant inductor-and-capacitor filters and switched band-pass filters. The overall combination would implement a switch function designed mathematically to exhibit desired frequency responses and to switch the signal in each frequency band to an analog-to-digital converter appropriate for that band to produce a digital intermediate-frequency signal for digital signal processing.

  13. Rational engineering of nanoporous anodic alumina optical bandpass filters

    NASA Astrophysics Data System (ADS)

    Santos, Abel; Pereira, Taj; Law, Cheryl Suwen; Losic, Dusan

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  14. Rational engineering of nanoporous anodic alumina optical bandpass filters.

    PubMed

    Santos, Abel; Pereira, Taj; Law, Cheryl Suwen; Losic, Dusan

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  15. Dual-band bandpass filter using composite metamaterial resonator

    NASA Astrophysics Data System (ADS)

    Jin, Yu-Ting; Si, Li-Ming; Zhang, Qing-Le; Wu, Yu-Ming; Lv, Xin

    2016-03-01

    A dual-band bandpass filter at X-band is proposed using composite metamaterial resonator consisting of an outer square closed-ring resonator (SCRR) and two inner electric inductance-capacitance (ELC) resonators. Numerical simulation and microwave measurement reveal that the filter exhibits two passbands centered at 8.76 GHz and 11.04 GHz, with 3 dB bandwidths of 130 MHz and 290 MHz, respectively. The complex dispersion relation of the filter is further derived based on the effective medium theory, where two balanced composite right-/left-handed bands are found, i.e. lines exhibiting two left-handed and two right-handed bands alternating. The proposed filter may find useful in dual-band or multi-band wireless communication systems.

  16. 3D Display Using Conjugated Multiband Bandpass Filters

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam; White, Victor E.; Shcheglov, Kirill

    2012-01-01

    Stereoscopic display techniques are based on the principle of displaying two views, with a slightly different perspective, in such a way that the left eye views only by the left eye, and the right eye views only by the right eye. However, one of the major challenges in optical devices is crosstalk between the two channels. Crosstalk is due to the optical devices not completely blocking the wrong-side image, so the left eye sees a little bit of the right image and the right eye sees a little bit of the left image. This results in eyestrain and headaches. A pair of interference filters worn as an optical device can solve the problem. The device consists of a pair of multiband bandpass filters that are conjugated. The term "conjugated" describes the passband regions of one filter not overlapping with those of the other, but the regions are interdigitated. Along with the glasses, a 3D display produces colors composed of primary colors (basis for producing colors) having the spectral bands the same as the passbands of the filters. More specifically, the primary colors producing one viewpoint will be made up of the passbands of one filter, and those of the other viewpoint will be made up of the passbands of the conjugated filter. Thus, the primary colors of one filter would be seen by the eye that has the matching multiband filter. The inherent characteristic of the interference filter will allow little or no transmission of the wrong side of the stereoscopic images.

  17. Narrow bandpass tunable terahertz filter based on photonic crystal cavity.

    PubMed

    He, Jinglong; Liu, Pingan; He, Yalan; Hong, Zhi

    2012-02-20

    We have fabricated a very narrow bandpass tunable terahertz (THz) filter based on a one-dimensional photonic crystal cavity. Since the filter consists of silicon wafers and air spacers, it has a very high quality factor of about 1500. The full width at half maximum (FWHM) of the passband is only about 200 MHz, and the peak transmission is higher than -4 dB. Besides, the central frequency can be tuned rapidly over the entire bandgap with the length of cavity adjusted by a motorized linear stage. Further analytical calculations indicate that a high-Q tunable filter with both high peak transmission and wide tunable range is possible if thinner silicon layers are used. PMID:22358169

  18. Rational engineering of nanoporous anodic alumina optical bandpass filters

    NASA Astrophysics Data System (ADS)

    Santos, Abel; Pereira, Taj; Law, Cheryl Suwen; Losic, Dusan

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  19. Frequency Selective Surface Bandpass Filters Applied To Thermophotovoltaic Generators

    NASA Astrophysics Data System (ADS)

    Horne, W. E.; Morgan, Mark D.; Horne, W. Paul; Sundaram, Vasan S.

    2004-11-01

    EDTEK, Inc. is developing three TPV applications, a portable diesel fueled generator for military and remote users, a hybrid solar-gas fueled power system intended for light industry and commercial 24-hour use, and a radioisotope fueled generator for deep-space spacecraft. The application of FSS bandpass filters for spectral control in these three different TPV applications has been analyzed. It has been determined that the design of the filter cannot be evaluated solely on the parameters of the filter itself. The interactions between the filter and the emitter and the TPV cells must be taken into account. In addition to the technical analysis of the converter, the overall system losses must be included in the analysis and the design requirements such as fuel efficiency, weight, generator size, cost and other factors must be included in the analysis. The analysis shows that the FSS filters are useful for producing the three systems with good efficiencies; however, different designs are required for the filters for each application.

  20. Far-infrared band-pass grid filters

    NASA Astrophysics Data System (ADS)

    MacDonald, Michael E.; Grossman, Erich N.

    1996-12-01

    The spectral performance of bandpass grid filters centered at terahertz frequencies is presented. The filters are composed of a periodic array of cross-shaped apertures in an evaporated metal film on a thin dielectric substrate. A commercial Fourier-transform spectrometer is used to measure spectral transmittance. Results are presented for filters using gold films of different thickness. The peak transmittance is correlated with the DC surface resistance Rs of the film, which is probed using an in situ test structure on the fabricated filters. This is true even though the gold films all have a thickness several times the classical skin depth at the resonant frequency. Measurements of Rs and peak transmittance at 77 K show an equivalent correlation, indicating that some of the loss is due to the finite conductivity of the gold film. The dielectric substrate causes a downward shift in the center frequency of the filter proportional to the dielectric constant and thickness of the substrate. The center frequency shifts rapidly with increasing dielectric thickness and reaches an asymptotic value reduced from the freestanding case by the square root of the mean dielectric constant. Measurements are compared to a finite-difference time domain model, which accurately predicts the center frequency, but does not account for losses. The performance of these filters, along with their simple fabrication, makes them useful frequency- selective elements at far-IR wavelengths.

  1. Bandpass filter arrays patterned by photolithography for multispectral remote sensing

    NASA Astrophysics Data System (ADS)

    Bauer, T.; Thome, Heidi; Eisenhammer, Thomas

    2014-10-01

    Optical remote sensing of the earth from air and space typically utilizes several channels from visible (VIS), near infrared (NIR) up to the short wave infrared (SWIR) spectral region. Thin-film optical filters are applied to select these channels. Filter wheels and arrays of discrete stripe filters are standard configurations. To achieve compact and light weight camera designs multi-channel filter plates or assemblies can be mounted close to the electronic detectors. Optics Balzers has implemented a micro-structuring process based on a sequence of multiple coatings and photolithography on the same substrate. High-performance band pass filters are applied by plasma assisted evaporation (plasma IAD) with advance plasma source (APS) technology and optical broad-band monitoring (BBM). This technology has already proven for various multi spectral imager (MSI) configurations on fused silica, sapphire and other substrates for remote sensing application. The optical filter design and performance is limited by the maximum coating thickness micro-structurable by photolithographic lift-off processes and by thermal and radiation load on the photoresist mask during the process Recent progress in image resolution and sensor selectivity requires improvements of optical filter performance. Blocking in the UV and NIR and in between the spectral cannels, in-band transmission and filter edge steepness are subject of current development. Technological limits of the IAD coating accuracy can be overcome by more precise coating technologies like plasma assisted reactive magnetron sputtering (PARMS) and combination with optical broadband monitoring (BBM). We present an overview about concepts and technologies for band-pass filter arrays for multi-spectral imaging at Optics Balzers. Recent performance improvements of filter arrays made by micro-structuring will be presented.

  2. Optically tunable acoustic wave band-pass filter

    SciTech Connect

    Swinteck, N.; Lucas, P.; Deymier, P. A.

    2014-12-15

    The acoustic properties of a hybrid composite that exhibits both photonic and phononic behavior are investigated numerically with finite-element and finite-difference time-domain simulations. The structure is constituted of a periodic array of photonic resonant cavities embedded in a background superlattice. The resonant cavities contain a photo-elastic chalcogenide glass that undergoes atomic-scale structural reorganization when irradiated with light having energy close to its band-gap. Photo-excitation of the chalcogenide glass changes its elastic properties and, consequently, augments the acoustic transmission spectrum of the composite. By modulating the intensity of light irradiating the hybrid photonic/phononic structure, the position and spectral width of phonon passing-bands can be controlled. This demonstration offers the technological platform for optically-tunable acoustic wave band-pass filters.

  3. 1 THz Micromachined Waveguide Band-Pass Filter

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Hu, Jiang; Zhang, Yong; Zheng, Zhongwan; Liu, Yupeng; Xu, Ruimin; Xue, Quan

    2016-05-01

    This paper presents a waveguide band-pass filter operating at the 0.75 ˜ 1.1 THz frequency band. The metal conductivity, the surface impedance, and the skin depth are investigated in the terahertz (THz) frequency band for more accurate designs, especially at the 1 THz and higher frequencies. Because the influence of the fabrication tolerance on the component performance cannot be negligible while the frequency increases, it is a necessary to adopt the simple structure with less resonant cavities for obtaining the given performance. Therefore, the filter in this paper is designed based on the TE301/TE102 dual-mode rectangular waveguide resonant cavities, which has fewer cavities and better rejection of the stop-band. The proposed filter is fabricated using the deep reactive ion etching (DRIE) micromachining technique. Measured results are in good agreement with simulations, which verifies the accuracy of the analysis above, and the design process is valuable to realize high-performance passive components while the frequency is up to 1 THz or higher frequencies.

  4. Dynamic, infrared bandpass filters prepared from polymer-stabilized cholesteric liquid crystals.

    PubMed

    Worth, Bradley; Lee, Kyung Min; Tondiglia, Vincent P; Myers, Joshua; Mou, Shin; White, Timothy J

    2016-09-01

    We report on the formulation and electrical control of the position and bandwidth of reflective bandpass filters prepared from cholesteric liquid crystal (CLC) in the infrared (3-5 μm). These filters are prepared from alignment cells employing infrared transparent electrodes and substrates. The optical nature of the electrodes is shown to strongly influence the resulting transmission of the bandpass filters outside of the spectral reflection. PMID:27607292

  5. Flexibly tunable multichannel filter and bandpass filter based on long-period fiber gratings

    NASA Astrophysics Data System (ADS)

    Han, Young-Geun; Hyuck Kim, Sang; Lee, Sang Bae

    2004-05-01

    The voltage-controllable multichannel filter based on multiply cascaded long-period fiber gratings with a divided coil heater will be proposed and experimentally demonstrated. It has several advantages of the large tuning range in both C- and L-band, multichannel operation, multiwavelength electivity, and bandwidth controllability. The tunable bandpass filter based on long-period fiber gratings ith the broad bandwidth over 6.5 nm, large tuning range over 30 nm, and excellent side mode suppression more than 40 dB will be also discussed.

  6. 1D linear-phase band-pass multiplierless FIR Hilbert transformers and filters

    NASA Astrophysics Data System (ADS)

    Pavlović, Vlastimir D.; Dončov, Nebojša S.; Ćirić, Dejan G.

    2016-06-01

    An original analytical method, based on modified Christoffel-Darboux formula, is used in the paper in order to synthesise a linear-phase band-pass finite impulse response (FIR) filter function that can have an effect of Hilbert transformer. New structure of the band-pass FIR filter in recursive realisation, together with the corresponding difference equation, is presented providing the efficient filter solution without multipliers. Several examples of filter types for different parity of two real free integer parameters, including a particular solution of Hilbert transformer, are considered in terms of required number of adders and values of cut-off frequencies of the pass and stop bands. A comparison of the proposed band-pass filter characteristics with those of a classical filter solution is provided in the paper.

  7. Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared.

    PubMed

    Stolberg-Rohr, Thomine; Hawkins, Gary J

    2015-01-12

    The ability of narrow bandpass filters to discriminate wavelengths between closely-separated gas absorption lines is crucial in many areas of infrared spectroscopy. As improvements to the sensitivity of infrared detectors enables operation in uncontrolled high-temperature environments, this imposes demands on the explicit bandpass design to provide temperature-invariant behavior. The unique negative temperature coefficient (dn/dT<0) of Lead-based (Pb) salts, in combination with dielectric materials enable bandpass filters with exclusive immunity to shifts in wavelength with temperature. This paper presents the results of an investigation into the interdependence between multilayer bandpass design and optical materials together with a review on invariance at elevated temperatures. PMID:25835704

  8. High-performance RC bandpass filter is adapted to miniaturized construction

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Miniaturized bandpass filter with RC networks is suitable for use in integrated circuits. The circuit consists of three stages of amplification with additional resistive and capacitive components to obtain the desired characteristics. The advantages of the active RC filter network are the reduction in size and weight and elimination of magnetic materials.

  9. Miniaturized sharp band-pass filter based on complementary electric-LC resonator

    NASA Astrophysics Data System (ADS)

    Torabi, Yalda; Dadashzadeh, Golamreza; Oraizi, Homayoon

    2016-04-01

    In this paper, a novel application of complementary electric-LC (CELC) resonator as a basic element to synthesize miniaturized sharp band-pass filters is introduced. The proposed metamaterial band-pass filter is a three-stage CELC-based device, where two shunt short-circuited stubs are employed in the input and output stages and a series gap is etched in the middle stage. By these means, a high-selectivity prototype band-pass filter with 2 % fractional bandwidth in S band is designed and fabricated. The out-of-band attenuation is better than 40 dB, and the upper and lower transition bands are also quite sharp due to the presence of two transmission zeros (nearly 60 and 30 dB fall in 0.2 GHz at lower and upper edges, respectively). Moreover, the filter is substantially miniaturized with a size of effective region of 1.3 cm × 1 cm at 2.9 GHz, which is quite smaller relative to conventional designs with the same performance. The fabrication and measurement of the proposed filter configuration attest to its expected desirable features. Therefore, the application of CELC resonator is proposed for super-compact sharp band-pass filters.

  10. Tunable optical bandpass filter with multiple flat-top bands in nanostructured resonators

    NASA Astrophysics Data System (ADS)

    Xie, Jun; Chen, Yuping; Lu, Wenjie; Chen, Xianfeng

    2011-03-01

    Based on second-order nonlinearity, we present a tunable optical bandpass filter at c-band by introducing a back quasiphase-matching technique with a nanostructured named multiple resonator waveguide. Two injecting forward lights and one backward propagating light interact with difference frequency generation. At that juncture, the transmission of the forward signal can be modulated via changing the forward control power. As a result, a tunable optical bandpass filter with multiple flat-top transmit bands of the forward signal can be formed in the waveguide.

  11. Alkali metal for ultraviolet band-pass filter

    NASA Technical Reports Server (NTRS)

    Mardesich, Nick (Inventor); Fraschetti, George A. (Inventor); Mccann, Timothy A. (Inventor); Mayall, Sherwood D. (Inventor); Dunn, Donald E. (Inventor); Trauger, John T. (Inventor)

    1993-01-01

    An alkali metal filter having a layer of metallic bismuth deposited onto the alkali metal is provided. The metallic bismuth acts to stabilize the surface of the alkali metal to prevent substantial surface migration from occurring on the alkali metal, which may degrade optical characteristics of the filter. To this end, a layer of metallic bismuth is deposited by vapor deposition over the alkali metal to a depth of approximately 5 to 10 A. A complete alkali metal filter is described along with a method for fabricating the alkali metal filter.

  12. Spectral and Wavefront Error Performance of WFIRST-AFTA Bandpass Filter Coating Prototypes

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Seide, Laurie; Pasquale, Bert A.; McMann, Joseph C.; Hagopian, John G.; Dominguez, Margaret Z.; Gong, Quian; Marx, Catherine T.

    2016-01-01

    The Cycle 5 design baseline for the Wide-Field Infrared Survey Telescope Astrophysics Focused Telescope Assets (WFIRST/AFTA) instrument includes a single wide-field channel (WFC) instrument for both imaging and slit-less spectroscopy. The only routinely moving part during scientific observations for this wide-field channel is the element wheel (EW) assembly. This filter-wheel assembly will have 8 positions that will be populated with 6 bandpass filters, a blank position, and a Grism that will consist of a three-element assembly to disperse the full field with an undeviated central wavelength for galaxy redshift surveys. All filter elements in the EW assembly will be made out of fused silica substrates (110 mm diameter) that will have the appropriate bandpass coatings according to the filter designations (Z087, Y106, J129, H158, F184, W149 and Grism). This paper presents and discusses the performance (including spectral transmission and reflected/transmitted wavefront error measurements) of a subset of bandpass filter coating prototypes that are based on the WFC instrument filter compliment. The bandpass coating prototypes that are tested in this effort correspond to the Z087, W149, and Grism filter elements. These filter coatings have been procured from three different vendors to assess the most challenging aspects in terms of the in-band throughput, out of band rejection (including the cut-on and cutoff slopes), and the impact the wavefront error distortions of these filter coatings will have on the imaging performance of the wide-field channel in the WFIRST/AFTA observatory.

  13. An optically tunable wideband optoelectronic oscillator based on a bandpass microwave photonic filter.

    PubMed

    Jiang, Fan; Wong, Jia Haur; Lam, Huy Quoc; Zhou, Junqiang; Aditya, Sheel; Lim, Peng Huei; Lee, Kenneth Eng Kian; Shum, Perry Ping; Zhang, Xinliang

    2013-07-15

    An optoelectronic oscillator (OEO) with wideband frequency tunability and stable output based on a bandpass microwave photonic filter (MPF) has been proposed and experimentally demonstrated. Realized by cascading a finite impulse response (FIR) filter and an infinite impulse response (IIR) filter together, the tunable bandpass MPF successfully replaces the narrowband electrical bandpass filter in a conventional single-loop OEO and serves as the oscillating frequency selector. The FIR filter is based on a tunable multi-wavelength laser and dispersion compensation fiber (DCF) while the IIR filter is simply based on an optical loop. Utilizing a long length of DCF as the dispersion medium for the FIR filter also provides a long delay line for the OEO feedback cavity and as a result, optical tuning over a wide frequency range can be achieved without sacrificing the quality of the generated signal. By tuning the wavelength spacing of the multi-wavelength laser, the oscillation frequency can be tuned from 6.88 GHz to 12.79 GHz with an average step-size of 0.128 GHz. The maximum frequency drift of the generated 10 GHz signal is observed to be 1.923 kHz over 1 hour and its phase noise reaches the -112 dBc/Hz limit of our measuring equipment at 10 kHz offset frequency. PMID:23938489

  14. Design and implementation of waveguide bandpass filter using complementary metaresonator

    NASA Astrophysics Data System (ADS)

    Haq, Tanveer ul; Khan, M. F.; Siddiqui, O. F.

    2016-01-01

    During past few years, designing of complementary metamaterials-based microwave devices have extensively increased. In this paper, passband filter for rectangular waveguide is designed using complementary symmetric split-ring resonator (CSSRR). By varying different geometrical parameters of CSSRR, the passband frequency and bandwidth can be varied. Effect of design parameter on quality factor of filter is also calculated. By appropriate choice of CSSRR geometrical parameters, a filter is proposed which gives passband of 2 GHz. The results are calculated numerically using HFSS 14.0.

  15. A novel band-pass filter based on a periodically drilled SIW structure

    NASA Astrophysics Data System (ADS)

    Coves, A.; Torregrosa-Penalva, G.; San-Blas, A. A.; Sánchez-Soriano, M. A.; Martellosio, A.; Bronchalo, E.; Bozzi, M.

    2016-04-01

    The design and fabrication of a band-pass step impedance filter based on high and low dielectric constant sections has been realized on substrate integrated waveguide (SIW) technology. The overall process includes the design of the ideal band-pass prototype filter, where the implementation of the impedance inverters has been carried out by means of waveguide sections of lower permittivity. This can be practically achieved by implementing arrays of air holes along the waveguide. Several SIW structures with and without arrays of air holes have been simulated and fabricated in order to experimentally evaluate their relative permittivity. Additionally, the equivalent filter in SIW technology has been designed and optimized. Finally, a prototype of the designed filter has been fabricated and measured, showing a good agreement between measurements and simulations, which demonstrates the validity of the proposed design approach.

  16. Compact Micromachined Bandpass Filters for Infrared Planetary Spectroscopy

    NASA Technical Reports Server (NTRS)

    Brown, Ari D.; Aslam, Shahid; Chervenak, James A.; Huang, Wei-Chung; Merrell, Willie; Quijada, Manuel

    2011-01-01

    The thermal instrument strawman payload of the Jupiter Europa Orbiter on the Europa Jupiter Science Mission will map out thermal anomalies, the structure, and atmospheric conditions of Europa and Jupiter within the 7-100 micron spectral range. One key requirement for the payload is that the mass cannot exceed 3.7 kg. Consequently, a new generation of light-weight miniaturized spectrometers needs to be developed. On the path toward developing these spectrometers is development of ancillary miniaturized spectroscopic components. In this paper, we present a strategy for making radiation hard and low mass FIR band pass metal mesh filters. Our strategy involves using MEMS-based fabrication techniques, which will permit the quasi-optical filter structures to be made with micron-scale precision. This will enable us to achieve tight control over both the pass band of the filter and the micromachined silicon support structure architecture, which will facilitate integration of the filters for a variety of applications.

  17. Microwave bandpass filters based on thin-film acoustic resonators: theory and experiment

    NASA Astrophysics Data System (ADS)

    Dvoesherstov, M. Yu.; Cherednik, V. I.

    2015-11-01

    We theoretically and experimentally analyze microwave thin-film acoustoelectronic bandpass ladder filters built on AlN-based thin-film acoustoelectronic microwave resonators operating in the frequency range 4.6-5 GHz and describe the technology of their fabrication. We demonstrate that the parameters of filters are mainly determined by the characteristics of resonators that make up the filter and show that the characteristics of a three-section ladder filter can be significantly improved by optimizing the areas of the upper electrodes of the series and parallel resonators contained in it.

  18. Effect of bandpass filtering on melodic contour identification by cochlear implant users.

    PubMed

    Galvin, John J; Fu, Qian-Jie

    2011-02-01

    Melodic contour identification was measured in cochlear implant (CI) and normal-hearing (NH) subjects for piano samples processed by four bandpass filters: low (310-620 Hz), middle (620-2480 Hz), high (2480-4960 Hz), and full (310-4960 Hz). NH performance was near-perfect for all filter ranges and much higher than CI performance. The best mean CI performance was with the middle frequency range; performance was much better for some CI subjects with the middle rather than the full filter. These results suggest that acoustic filtering may reduce potential mismatches between fundamental frequencies and harmonic components thereby improving CI users' melodic pitch perception. PMID:21361410

  19. Microstrip Hairpin Bandpass Filter Using Modified Minkowski Fractal-Shape for Suppression of Second Harmonic

    NASA Astrophysics Data System (ADS)

    Lalbakhsh, Ali; Lotfi Neyestanak, Abbas Ali; Naser-Moghaddasi, Mohammad

    In this paper, a novel microstrip hairpin-line bandpass filter which employs a modified Minkowski fractal shape is proposed. Although conventional hairpin-line filters are popular for RF front ends, they suffer from undesired spurious responses located at the second harmonic, which causes asymmetry in the upper skirt band. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shape. To validate this novel geometry, the proposed filters are fabricated and measured. Simulated results are in good agreement with measured results.

  20. Ultra-narrow bandpass filters for infrared applications with improved angle of incidence performance

    NASA Astrophysics Data System (ADS)

    Rahmlow, Thomas D.; Fredell, Markus; Chanda, Sheetal; Johnson, Robert

    2016-05-01

    Narrow band-pass optical interference filters are used for a variety of applications to improve signal quality in laser based systems. Applications include LIDAR, sensor processing and free space communications. A narrow band width optical filter allows for passage of the laser signal while rejecting ambient light. The more narrow the bandwidth, the better the signal to noise. However, the bandwidth of a design for a particular application is typically limited by a number of factors including spectral shift over the operational angles of incidence, thermal shift over the range of operating temperature and, in the case of laser communication, rejection of adjacent laser channels. The trade-off of these parameters can significantly impact system design and performance. This paper presents design and material approaches to maximize the performance of narrow bandpass filters in the infrared.

  1. Tunable coherence-free microwave photonic bandpass filter based on double cross gain modulation technique.

    PubMed

    Chan, Erwin H W

    2012-10-01

    A tunable, coherence-free, high-resolution microwave photonic bandpass filter, which is compatible to be inserted in a conventional fiber optic link, is presented. It is based on using two cross gain modulation based wavelength converters in a recursive loop. The double cross gain modulation technique solves the semiconductor optical amplifier facet reflection problem in the conventional recursive structure; hence the new microwave photonic signal processor has no coherent interference and no phase-induced intensity noise. It allows arbitrary narrow-linewidth telecommunication-type lasers to be used while enabling stable filter operation to be realized. The filter passband frequency can be tuned by using a wavelength tunable laser and a wavelength dependent time delay component. Experimental results demonstrate robust high-resolution bandpass filter operation with narrow-linewidth sources, no phase-induced intensity noise and a high signal-to-noise ratio performance. Tunable coherence-free operation of the high-resolution bandpass filter is also demonstrated. PMID:23188262

  2. Widely tunable single bandpass microwave photonic filter based on Brillouin-assisted optical carrier recovery.

    PubMed

    Wang, Wen Ting; Liu, Jian Guo; Sun, Wen Hui; Wang, Wei Yu; Wang, Sun Long; Zhu, Ning Hua

    2014-12-01

    A widely tunable single bandpass microwave photonic filter (MPF) based on Brillouin-assisted optical carrier recovery in a highly nonlinear fiber (HNLF) with only one optical filter is proposed and experimentally demonstrated. The fundamental principle lies in the fact that the suppressed optical carrier of the phase modulated optical signal could be recovered by the stimulated Brillouin scattering (SBS) amplification effect. When phase modulated optical signals go through an optical filter with a bandpass response, the optical carrier and the upper sidebands suffer from the suppression of the optical filter because they fall in the stopband of that. In our system, the optical carrier could be recovered by the SBS operation around 38 dB. The MPF is achieved by one-to-one mapping from the optical domain to the electrical domain only when one of phase modulated sidebands lies in the bandpass of the optical filter. It shows an excellent selectivity with a 3-dB bandwidth of 170 MHz over a tuning frequency range of 9.5-32.5 GHz. The out-of-band suppression of the MPF is more than 20 dB. Moreover, the MPF shows an excellent shape factor with 10-dB bandwidth of only 520 MHz. The frequency response of the MPF could be widely tuned by changing the frequency difference between the frequency of the optical carrier and the center frequency of the bandpass of the optical filter. A proof-of-concept experiment is carried out to verify the proposed approach. PMID:25606864

  3. Radiation Hard Bandpass Filters for Mid- to Far-IR Planetary Instruments

    NASA Technical Reports Server (NTRS)

    Brown, Ari D.; Aslam, Shahid; Chervenack, James A.; Huang, Wei-Chung; Merrell, Willie C.; Quijada, Manuel; Steptoe-Jackson, Rosalind; Wollack, Edward J.

    2012-01-01

    We present a novel method to fabricate compact metal mesh bandpass filters for use in mid- to far-infrared planetary instruments operating in the 20-600 micron wavelength spectral regime. Our target applications include thermal mapping instruments on ESA's JUICE as well as on a de-scoped JEO. These filters are novel because they are compact, customizable, free-standing copper mesh resonant bandpass filters with micromachined silicon support frames. The filters are well suited for thermal mapping mission to the outer planets and their moons because the filter material is radiation hard. Furthermore, the silicon support frame allows for effective hybridization with sensors made on silicon substrates. Using a Fourier Transform Spectrometer, we have demonstrated high transmittance within the passband as well as good out-of-band rejection [1]. In addition, we have developed a unique method of filter stacking in order to increase the bandwidth and sharpen the roll-off of the filters. This method allows one to reliably control the spacing between filters to within 2 microns. Furthermore, our method allows for reliable control over the relative position and orienta-tion between the shared faces of the filters.

  4. Compact Bandpass Filter Based on Parallel-coupled Lines and Quasi-lumped Structure

    NASA Astrophysics Data System (ADS)

    Ding, Chen; Li, Jiao; Wei, Feng; Shi, Xiao-Wei

    2016-01-01

    A compact microstrip bandpass filter (BPF) using quarter-wavelength resonators is proposed based on the parallel-coupled lines (PCLs) and quasi-lumped structure. A method based on the matrix and network transformation of cascaded-quadruplet (CQ) filters is investigated and successfully applied to the BPF design. The design formulas for the proposed BPF are analytically developed. Specifically, in order to verify the feasibility of the proposed method, three BPFs centering at 1.575 GHz with different FBWs are designed. Good agreement between the simulated and measured results is observed. Moreover, the designed filters can achieve a wide stopband.

  5. Design and manufacture of a bandpass filter with high transmittance and steep edge on both sides

    NASA Astrophysics Data System (ADS)

    Wang, Ruisheng; Lü, Shaobo; Yin, Xiaojun; Zhao, Shuaifeng; Sun, Yan

    2016-01-01

    By using Nb2O5 and SiO2 as the coating material, a 152 layers (12 cavities) bandpass film stack with steep edge on both sides was designed. Multiple thickness control methods, including direct optical monitoring control and time control were used in coating strategy. To confirm the feasibility of this coating strategy, a process simulation was performed using Simulator software, and the simulation result indicated that relative thickness errors for all layers were less than ±0.1%. A bandpass filter with this film stack on one side was manufactured by using a plasma assisted reactive magnetic sputtering coating machine. The measuring result shows that the peak transmittance of the filter (without AR on backside) is up to 95.4%, and the steepness of both blocking slope are less than λ/100.

  6. A band-pass plasmonic filter with dual-square ring resonator

    NASA Astrophysics Data System (ADS)

    Duan, Gaoyan; Lang, Peilin; Wang, Lulu; Yu, Li; Xiao, Jinghua

    2014-09-01

    In this paper, we show the simulation of a plasmonic band-pass filter which consists of two surface plasmon polaritons (SPPs) waveguides and a resonator in metal-insulator-metal (MIM) structure. The resonator is formed by two square rings and a patch between them. The patch is a tiny rectangle cavity in order to transfer the SPPs from one ring to the other. The finite element method (FEM) method is employed in simulation. The results show that the dual-ring resonator performs better than a single ring does. The 3 dB bandwidth near the peak wavelength λ = 1054 nm is merely 31.7 nm. The resonant wavelength can be shifted by changing the side length of the square ring. This narrow band-pass filter is easy to fabricate and has potential applications in future integrated optical circuits.

  7. Project Report: Reducing Color Rivalry in Imagery for Conjugated Multiple Bandpass Filter Based Stereo Endoscopy

    NASA Technical Reports Server (NTRS)

    Ream, Allen

    2011-01-01

    A pair of conjugated multiple bandpass filters (CMBF) can be used to create spatially separated pupils in a traditional lens and imaging sensor system allowing for the passive capture of stereo video. This method is especially useful for surgical endoscopy where smaller cameras are needed to provide ample room for manipulating tools while also granting improved visualizations of scene depth. The significant issue in this process is that, due to the complimentary nature of the filters, the colors seen through each filter do not match each other, and also differ from colors as seen under a white illumination source. A color correction model was implemented that included optimized filter selection, such that the degree of necessary post-processing correction was minimized, and a chromatic adaptation transformation that attempted to fix the imaged colors tristimulus indices based on the principle of color constancy. Due to fabrication constraints, only dual bandpass filters were feasible. The theoretical average color error after correction between these filters was still above the fusion limit meaning that rivalry conditions are possible during viewing. This error can be minimized further by designing the filters for a subset of colors corresponding to specific working environments.

  8. Method for experimental determination of the contribution of individual sources to total noise. [using bandpass filter for signal analysis

    NASA Technical Reports Server (NTRS)

    Rubichev, N. A.

    1973-01-01

    Multiple noise sources generating signals in a mechanical device are analyzed by considering the medium transmitting the sound as linear, and by using a band filter with bandpass for synchronous detection and signal transformation.

  9. Note: An ultranarrow bandpass filter system for single-photon experiments in quantum optics

    NASA Astrophysics Data System (ADS)

    Höckel, David; Martin, Eugen; Benson, Oliver

    2010-02-01

    We describe a combined ultranarrow bandpass filtering setup for single-photon experiments in quantum optics. The filter is particularly suitable for single-photon electromagnetically induced transparency (EIT) experiments, but can also be used in several similar applications. A multipass planar Fabry-Pérot etalon together with polarization filters and spatial filtering allows 114 dB pump beam suppression, while the signal beam is attenuated by just 4 dB, although both wavelengths are only separated by 0.025 nm (9.2 GHz). The multipass etalon alone accounts for 46 dB suppression while it has a peak transmission of 65%. We demonstrate EIT experiments in Cs vapor at room temperature with probe power in the femtowatt regime using this filter.

  10. System design for a million channel digital spectrum analyzer /MCSA/. [of bandpass filtering in SETI receivers

    NASA Technical Reports Server (NTRS)

    Peterson, A.; Narasimha, M.; Narayan, S.

    1980-01-01

    The system design of a wideband (8 MHz) million-channel digital spectrum analyzer for use with a SETI receiver is presented. The analyzer makes use of a digital bandpass filter bank for transforming the wideband input signal into a specified number (120) of uniform narrowband output channels by the use of a Fourier transform digital processor combined with a prototype digital weighting network (finite impulse response filter). The output is then processed separately by 120 microprocessor-based discrete Fourier transform computers, each producing 8190 output channels of approximately 8 Hz bandwidth by the use of an 8190-point prime factor algorithm.

  11. An algorithm used for quality criterion automatic measurement of band-pass filters and its device implementation

    NASA Astrophysics Data System (ADS)

    Liu, Qianshun; Liu, Yan; Yu, Feihong

    2013-08-01

    As a kind of film device, band-pass filter is widely used in pattern recognition, infrared detection, optical fiber communication, etc. In this paper, an algorithm for automatic measurement of band-pass filter quality criterion is proposed based on the proven theory calculation of derivate spectral transmittance of filter formula. Firstly, wavelet transform to reduce spectrum data noises is used. Secondly, combining with the Gaussian curve fitting and least squares method, the algorithm fits spectrum curve and searches the peak. Finally, some parameters for judging band-pass filter quality are figure out. Based on the algorithm, a pipeline for band-pass filters automatic measurement system has been designed that can scan the filter array automatically and display spectral transmittance of each filter. At the same time, the system compares the measuring result with the user defined standards to determine if the filter is qualified or not. The qualified product will be market with green color, and the unqualified product will be marked with red color. With the experiments verification, the automatic measurement system basically realized comprehensive, accurate and rapid measurement of band-pass filter quality and achieved the expected results.

  12. Metamaterial composite bandpass filter with an ultra-broadband rejection bandwidth of up to 240 terahertz

    NASA Astrophysics Data System (ADS)

    Strikwerda, Andrew C.; Zalkovskij, Maksim; Lund Lorenzen, Dennis; Krabbe, Alexander; Lavrinenko, Andrei V.; Uhd Jepsen, Peter

    2014-05-01

    We present a metamaterial, consisting of a cross structure and a metal mesh filter, that forms a composite with greater functional bandwidth than any terahertz (THz) metamaterial to date. Metamaterials traditionally have a narrow usable bandwidth that is much smaller than common THz sources, such as photoconductive antennas and difference frequency generation. The composite structure shown here expands the usable bandwidth to exceed that of current THz sources. To highlight the applicability of this combination, we demonstrate a series of bandpass filters with only a single pass band, with a central frequency (f0) that is scalable from 0.86-8.51 THz, that highly extinguishes other frequencies up to >240 THz. The performance of these filters is demonstrated in experiment, using both air biased coherent detection and a Fourier transform infrared spectrometer (FTIR), as well as in simulation. We present equations—and discuss their scaling laws—which detail the f0 and full width at half max (Δf) of the pass band, as well as the required geometric dimensions for their fabrication using standard UV photolithography and easily achievable fabrication linewidths. With these equations, the geometric parameters and Δf for a desired frequency can be quickly calculated. Using these bandpass filters as a proof of principle, we believe that this metamaterial composite provides the key for ultra-broadband metamaterial design.

  13. Optical bandpass filters for detector arrays' modulation transfer function estimation by means of laser speckle

    NASA Astrophysics Data System (ADS)

    Astar, William

    1996-06-01

    Two apertures, a square slit (SS) and a diamond slit (DS), both zero'th-order magnitude transparencies with bandpass filters in their optical transfer functions (OTFs), are designed and optimized for the purpose of modulation transfer function (MTF) evaluation of detector arrays by means of laser speckle. The SS and DS apertures are compared to an existing design, the extended frequency aperture, and show, respectively, improvements of 464% and 58% in filter magnitude; improvements of -13.4% (a compromise) and 17% in bandwidth; and improvements of 627% and 423% in throughput, implying a greatly reduced laser power requirement. As a result, they should significantly enhance detector arrays' MTF evaluations and at a greatly reduced cost. The DS aperture possesses identical OTFs in both the horizontal and vertical directions, enabling MTF evaluation using the bandpass filters in those directions from the same speckle data frame--previously not possible. The DS aperture can be further modified to yield filter magnitude and bandwidth improvements of 111% and 40%, respectively; although becoming easier to fabricate, this modification would be a lower throughput improvement of 310% over the existing design.

  14. W-band waveguide bandpass filter with E-plane cut.

    PubMed

    Furtula, Vedran; Salewski, Mirko

    2014-07-01

    In this paper, we present a design and measurements of a five-section bandpass filter with a passband from 96 to 106 GHz. The insertion loss is less than 1.4 dB in the passband, and the rejection is better than 40 dB in the range from 115 to 142 GHz. We use transmission line coupling theory based on Tchebyscheff's synthesis in order to provide an initial guess for the geometrical parameters of the filter such as cavity lengths and coupling widths. The filter is manufactured from brass in two halves in the E-plane cut topology. The S-parameters of the filter are measured and compared with the simulations. The measured passband insertion loss is approximately 0.4 dB worse than in the simulation, and the measured passband width is approximately 3.4% narrower. The measured filter attenuation roll-off corresponds well to the simulation. We also compare our S-parameter measurements of the E-plane filter with corresponding measurements of a very similar H-plane filter. The transmission and reflection characteristics of the E-plane filter are better than those of the H-plane filter. PMID:25085158

  15. Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot

    PubMed Central

    Mezaal, Yaqeen S.; Eyyuboglu, Halil T.

    2016-01-01

    A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered. PMID:27054755

  16. Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot.

    PubMed

    Mezaal, Yaqeen S; Eyyuboglu, Halil T

    2016-01-01

    A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered. PMID:27054755

  17. Polarization insensitive wide-angle triple-band metamaterial bandpass filter

    NASA Astrophysics Data System (ADS)

    Fu, Wenyue; Han, Yuchen; Li, Jiandong; Wang, Haoshen; Li, Haipeng; Han, Kui; Shen, Xiaopeng; Cui, Tiejun

    2016-07-01

    In this letter, we report the design, fabrication and measurement of a polarization insensitive wide-angle triple-band metamaterial bandpass filter (BPF) in the microwave frequency. The proposed BPF consists of two identical metal resonant units which have three concentric square slots separated by a dielectric layer. Experimental results show that the BPF has three distinctive transmission bands centered at frequencies 6.22 GHz, 9.46 GHz and 12.14 GHz with transmission rates of  ‑0.40 dB, ‑0.71 dB and  ‑1.40 dB, respectively, agreeing well with simulation results. By introducing the substrate integrated waveguide, the filter is valid to a wide range of incident angles for both transverse electric and transverse magnetic polarizations. The triple-band metamaterial BPF can be used as multiband filters and radomes owing to its multiband transmissions, polarizations insensitive and wide-angle responses.

  18. Solar-blind ultraviolet band-pass filter based on metal—dielectric multilayer structures

    NASA Astrophysics Data System (ADS)

    Wang, Tian-Jiao; Xu, Wei-Zong; Lu, Hai; Ren, Fang-Fang; Chen, Dun-Jun; Zhang, Rong; Zheng, You-Dou

    2014-07-01

    Solar-blind ultraviolet (UV) band-pass filter has significant value in many scientific, commercial, and military applications, in which the detection of weak UV signal against a strong background of solar radiation is required. In this work, a solar-blind filter is designed based on the concept of “transparent metal”. The filter consisting of Al/SiO2 multilayers could exhibit a high transmission in the solar-blind wavelength region and a wide stopband extending from near-ultraviolet to infrared wavelength range. The central wavelength, bandwidth, Q factor, and rejection ratio of the passband are numerically studied as a function of individual layer thickness and multilayer period.

  19. Investigation of Spectral Characteristics for Microstructured Quasi-Optical Bandpass Subteraherz Filters

    NASA Astrophysics Data System (ADS)

    Kuznetsov, S. A.; Gelfand, A. V.

    2016-03-01

    The electrodynamic features of quasi-optical bandpass filters based on multilayer microstructured frequency selective surfaces intended for effective spectral selection of subteraherz electromagnetic radiation are considered. As an optimal solution, the multiplex filters are highlighted wherein tripole-slot self-bearing copper microstructures free from dielectric substrates are employed. The results of the experimental development for such filters are presented by the example of structures with resonant transmission at the frequencies of 0.6 and 1 THz, and the details of testing their spectral performance in the range of 0.1-1.5 THz using a BWO spectroscopy technique are described. Good agreement between the experimental data and the results of theoretical predictions is demonstrated.

  20. Photosensitive post tuning of chalcogenide Te 20As 30Se 50 narrow bandpass filters

    NASA Astrophysics Data System (ADS)

    Shen, Weidong; Cathelinaud, Michel; Lequime, Michel; Nazabal, Virginie; Liu, Xu

    2008-07-01

    We present an experimental study on the photosensitive properties of narrow bandpass filters based on a chalcogenide Te 20As 30Se 50 (TAS) spacer. The transmittance curve of single TAS layer was shifted towards long wavelength direction after 2 h exposure by Xenon arc lamp. The refractive index and extinction coefficient were both increased together with a red shift of optical gap. A maximum 1.7% photo-induced effect was observed. Narrow band filters constituted by TAS and cryolite were manufactured by electron beam deposition. The transmittance spectrum of the filter during the exposure by a wide band source was in situ measured and the resonant wavelength was observed to turn longer gradually till saturation. A spatially localized central wavelength change up to 5.7 nm was finally obtained. The stability of the photo-induced effect was studied and some comments were given at the end of this paper.

  1. Dual-band bandpass tunable microwave photonic filter based on stimulated Brillouin scattering

    NASA Astrophysics Data System (ADS)

    Li, Jia-qi; Xiao, Yong-chuan; Dong, Wei; Zhang, Xin-dong

    2016-07-01

    A dual-band bandpass microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is theoretically analyzed and experimentally demonstrated. Two separated tunable laser sources (TLSs) are employed to generate two passbands by implementing phase modulation to amplitude modulation conversion by using SBS induced sideband amplification. The center frequencies of both passbands can be independently tuned ranging from 1 GHz to 19 GHz. High resolution with 3 dB bandwidth less than 30 MHz and large out-of-band rejection about 40 dB under 25 mW optical pump power are achieved.

  2. Design of cross-coupled planar microstrip band-pass filters using a novel adjustment method

    NASA Astrophysics Data System (ADS)

    Alkafaji, Muhammed S. S.

    2015-02-01

    In this paper the design of a cross-coupled planar microwave band-pass filter using open-loop square microstrip resonators, with two symmetrically placed attenuation poles, is presented. The design starts from the following specifications: central frequency 3GHz, 150MHz bandwidth, 1dB ripple in the pass-band corresponding to return loss of 6.8dB.The adjustment method using additional ports placed on each resonator of the filter is used, allowing the interconnection of the filter structure with external lumped elements. Connecting a reactive element (capacitor) from such an additional port to ground allows a fine tuning of the resonator. Connecting a reactive element between two such additional ports allows a fine change in the coupling coefficient between these resonators. After adding four extra ports and connecting the external elements (capacitors), it is possible to use fast circuit simulation software to optimize the filter's response. Then all these capacitors have to be gradually eliminated, by compensating their effects through fine changes back in the layouts. If some specific issues are properly handled, this procedure improves considerably the quality of the final design of the filter. After a thorough optimization of the layout, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing this way the efficiency of the applied optimization method.

  3. Design and Specification of Optical Bandpass Filters for Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.; Tsevetanov, Zlatan; Woodruff, Bob; Mooney, Thomas A.

    1998-01-01

    Advanced optical bandpass filters for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) have been developed on a filter-by-filter basis through detailed studies which take into account the instrument's science goals, available optical filter fabrication technology, and developments in ACS's charge-coupled-device (CCD) detector technology. These filters include a subset of filters for the Sloan Digital Sky Survey (SDSS) which are optimized for astronomical photometry using today's charge-coupled-devices (CCD's). In order for ACS to be truly advanced, these filters must push the state-of-the-art in performance in a number of key areas at the same time. Important requirements for these filters include outstanding transmitted wavefront, high transmittance, uniform transmittance across each filter, spectrally structure-free bandpasses, exceptionally high out of band rejection, a high degree of parfocality, and immunity to environmental degradation. These constitute a very stringent set of requirements indeed, especially for filters which are up to 90 mm in diameter. The highly successful paradigm in which final specifications for flight filters were derived through interaction amongst the ACS Science Team, the instrument designer, the lead optical engineer, and the filter designer and vendor is described. Examples of iterative design trade studies carried out in the context of science needs and budgetary and schedule constraints are presented. An overview of the final design specifications for the ACS bandpass and ramp filters is also presented.

  4. Compact Dual-Band Bandpass Filter Using Stubs Loaded Ring Resonator

    NASA Astrophysics Data System (ADS)

    Xu, Jin

    2016-01-01

    This paper presents a novel second-order dual-band bandpass filter (BPF) by using proposed stubs loaded ring resonator. The resonant behavior of proposed stubs loaded ring resonator is analyzed by even-/odd-mode method, which shows its multiple-mode resonant characteristic. Parameters sweep is done so as to give the design guidelines. As an example, a second-order dual-band BPF operating at 1.8/5.2 GHz for GSM and WLAN applications is designed, fabricated and measured. The fabricated filter has a very compact size of 0.05λg×0.15λg. Measured results also show that the proposed dual-band BPF has a better than 20 dB rejection upper stopband from 5.47 GHz to 12.56 GHz. Good agreement is shown between the simulated and measured results.

  5. Tunable all-optical single-bandpass photonic microwave filter based on spectrally sliced broad optical source and phase modulation.

    PubMed

    Chen, Ming; Pan, Wei; Zou, Xihua; Luo, Bin; Yan, Lianshan; Liu, Xinkai

    2013-01-10

    A tunable all-optical single-bandpass photonic microwave filter (PMF) based on spectrally sliced broadband optical source and phase modulation is proposed and experimentally demonstrated. A broadband optical source and a Mach-Zehnder interferometer (MZI) are used to generate continuous optical spectral samples, which are employed to form a finite impulse response filter with a single-bandpass response with the help of a single-mode fiber. A phase modulator is then adopted to eliminate the baseband components in the filtering response. The center frequency of the PMF can be tuned by changing the free spectral range of the MZI. An experiment is performed, and the results demonstrate that the proposed PMF has a single-bandpass without baseband components and a tuning range of 5-15 GHz. PMID:23314649

  6. Continued Development of an Ultra-Narrow Bandpass Filter for Solar Research

    NASA Technical Reports Server (NTRS)

    Rust, David M.

    1993-01-01

    The objective of work under this task was to develop ultranarrow optical bandpass filters and related technology necessary for construction of a compact solar telescope capable of operating unattended in space. The scientific problems to which such a telescope could be applied include solar seismology, solar activity monitoring, solar irradiance variations, solar magnetic field evolution, and the location of targets for narrow-field specialized telescopes. We have demonstrated a Y-cut lithium-niobate Fabry-Perot etalon. This filter will be used on the Flare Genesis Experiment. We also obtained solar images with a Z-cut etalon. The technical report on etalon filters is attached to this final report. We believe that work under this grant will lead to the commercial availability of a universal optical filter with approximately 0.1 A bandwidth. Progress was made toward making a suitable 1-2 A tunable blocker filter, but it now appears that the best approach is to make a double-cavity etalon that will not require such a narrow blocker. Broader band blockers are commercially available.

  7. Wide Bandpass and Narrow Bandstop Microstrip Filters based on Hilbert fractal geometry: design and simulation results.

    PubMed

    Mezaal, Yaqeen S; Eyyuboglu, Halil T; Ali, Jawad K

    2014-01-01

    This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, -28 dB return loss and -0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, -0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems. PMID:25536436

  8. Wide Bandpass and Narrow Bandstop Microstrip Filters Based on Hilbert Fractal Geometry: Design and Simulation Results

    PubMed Central

    Mezaal, Yaqeen S.; Eyyuboglu, Halil T.; Ali, Jawad K.

    2014-01-01

    This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, −28 dB return loss and −0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, −0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems. PMID:25536436

  9. Symmetrical band-pass loudspeaker systems

    NASA Astrophysics Data System (ADS)

    Matusiak, Grzegorz Piotr

    2001-12-01

    Loudspeaker systems are analyzed in a doctoral dissertation. The dissertation concerns loudspeaker systems, which are known as subwoofers or band-pass loudspeaker systems. Their advantages include: high- quality sound reproduction in the low-frequency range, small dimensions, small nonlinear distortions and the fact that they can be placed anywhere in a room or car. Band-pass loudspeaker systems are used widely in the so- called Home Theatre as well as to provide sound in cinema, theatre, concert, discotheque, opera, operetta, philharmonic and amphitheater halls, at open-air concerts, and so on. Various designs are mass-produced by a large number of manufacturers. The study covers an analysis of band-pass loudspeaker systems to which the frequency transformation, i.e. the reactance transformation, has been applied. Since this is a symmetrical transformation, amplitude frequency responses of the studied band-pass systems are also symmetrical (logarithmic scale of a frequency). As a result, the high-pass loudspeaker system design method, known as the Thiele-Small, Benson analysis, can be employed. The investigations include the formulation of band-pass system equations (fourth, sixth and eighth-order polynomials) and the subsequent derivation of relations for the calculation of system parameters. The obtained results enable the calculation of optimum designs for prescribed alignments, e.g. (Chebyshev) equal-ripple, (Butterworth) maximally flat, or quasi-maximally flat (QB). The analysis covers fourth, sixth and eighth-order symmetrical systems. Eighth-order systems have been divided into three kinds according to three ways of physical realization. The doctoral dissertation includes band-pass loudspeaker systems, which can be designed with active or passive filters or without the filter. Designed systems consist of a loudspeaker whose front of a diaphragm is loaded with a Helmholtz resonator, i.e. an enclosure with a vent, which radiates sound outwards. The back is

  10. Thermally stable narrow-bandpass filter prepared by reactive ion-assisted sputtering.

    PubMed

    Tsai, R Y; Chang, C S; Chu, C W; Chen, T; Dai, F; Lin, D; Yan, S; Chang, A

    2001-04-01

    Thermal stabilities of three-cavity narrow-bandpass (NB) filters with high-index half-wave spacers and 78-102 layers of Ta(2)O(5) and SiO(2) prepared by reactive ion-assisted bipolar direct-current (dc) magnetron sputtering of tantalum and silicon targets, respectively, were investigated. Pure argon and pure oxygen were used as the sputtering gas and the reactant, respectively. The oxygen gas was introduced and ionized through the ion gun and toward the unheated BK7 glass substrate. The refractive indices of single-layer Ta(2)O(5) and SiO(2) films were 2.1 and 1.45, respectively, at 1550 nm, which were comparable with those of films prepared by other ion-assisted coating techniques. The moisture-resistant properties of the films were excellent as evidenced from the water-immersion test, implying that the packing density of the films was close to that of their bulk materials. The temperature-dependant wavelength shifts of the NB filters were <3 x 10(-3) nm/ degrees C at temperatures of <75 degrees C, indicating that the temperature-induced wavelength shift of the filter was <0.15 nm when the temperatures were raised from room temperature to 75 degrees C, which was compliant with Bellcore GR-1209-CORE generic requirements of NB filters used for optical-fiber communication systems. PMID:18357152

  11. The Ring of Fire - an internal illimination system for detector sensitivity and filter bandpass characterization

    SciTech Connect

    Scarpine, Victor E.; Kent, Stephen M.; Deustua, Susana E.; Sholl, Michael J.; Mufson, Stuart L.; Ott, Melanie N.; Wiesner, Matthew P.; Baptitst, Brian J.; /Indiana U.

    2010-07-01

    We describe a prototype of an illumination system, the Ring of Fire (ROF), which is used as part of an internal calibration system for large focal plane detector arrays in TMA (Three Mirror Anastigmat) telescope designs. Such designs have been proposed for the SNAP (SuperNova Acceleration Probe) version of a Joint Dark Energy Mission (JDEM). The ROF system illuminates the focal plane with a light beam the closely matches that of the telescope and is used for creating high spatial frequency flat fields and monitoring filter bandpasses for experiments that demand a highly accurate characterization of the detectors. We present measurements of a mockup of this prototype ROF design including studies in variations in illumination across a large focal plane.

  12. Learning Multiple Band-Pass Filters for Sleep Stage Estimation: Towards Care Support for Aged Persons

    NASA Astrophysics Data System (ADS)

    Takadama, Keiki; Hirose, Kazuyuki; Matsushima, Hiroyasu; Hattori, Kiyohiko; Nakajima, Nobuo

    This paper proposes the sleep stage estimation method that can provide an accurate estimation for each person without connecting any devices to human's body. In particular, our method learns the appropriate multiple band-pass filters to extract the specific wave pattern of heartbeat, which is required to estimate the sleep stage. For an accurate estimation, this paper employs Learning Classifier System (LCS) as the data-mining techniques and extends it to estimate the sleep stage. Extensive experiments on five subjects in mixed health confirm the following implications: (1) the proposed method can provide more accurate sleep stage estimation than the conventional method, and (2) the sleep stage estimation calculated by the proposed method is robust regardless of the physical condition of the subject.

  13. Photonic-assisted microwave phase shifter using a DMZM and an optical bandpass filter.

    PubMed

    Li, Wei; Sun, Wen Hui; Wang, Wen Ting; Wang, Li Xian; Liu, Jian Guo; Zhu, Ning Hua

    2014-03-10

    We propose and demonstrate a photonic-assisted wideband 360° microwave phase shifter based on a conventional dual-drive Mach-Zehnder modulator (DMZM) and an optical bandpass filter (OBPF). The two arms of the DMZM are driven by the fundamental microwave signal to be phase shifted and its frequency doubled component, respectively. The OBPF followed after the DMZM is used to remove the optical carrier and the sidebands at either side of the optical carrier. As a result, only two sidebands corresponding to the fundamental microwave signal and its frequency doubled component, respectively, are left. Moreover, the phase shift between the two sidebands can be continuously tunable by adjusting the bias voltage of the DMZM. This phase shift is mapped to the fundamental microwave signal which is recovered by beating the two sidebands in a photodetector (PD). The proposed approach is theoretically analyzed and experimentally verified. PMID:24663892

  14. Tunable bandpass microwave photonic filter with ultrahigh stopband attenuation and skirt selectivity.

    PubMed

    Jiang, Fan; Yu, Yuan; Tang, Haitao; Xu, Lu; Zhang, Xinliang

    2016-08-01

    we propose and demonstrate a bandpass microwave photonic filter (MPF) with ultrahigh stopband attenuation and skirt selectivity based on a simple signal cancellation technique. By injecting two phase modulated signals located on opposite sides of two resonant gain peaks of a Fabry-Pérot semiconductor optical amplifier (FP-SOA), two microwave frequency responses can be generated by the two input signals, respectively. The two frequency responses will add together within the passband but cancel each other out within the stopband, thus generating a MPF with simultaneous ultrahigh stopband attenuation and skirt selectivity. In the experiment the obtained MPF exhibits single passband in the range from 0 to 18 GHz and is tunable from 4 to 16 GHz by adjusting the laser wavelengths. During the tuning process the maximum stopband attenuation is 76.3 dB and the minimum 30-dB to 3-dB bandwidth shape factor is 3.5. PMID:27505828

  15. Electronically reconfigurable bandpass microwave photonic filter using a windowed optical frequency comb

    NASA Astrophysics Data System (ADS)

    Deng, Hong; Fu, Songnian; Tang, Ming; Liu, Deming

    2015-03-01

    A center frequency-tunable multi-tap bandpass microwave photonic filter (MPF) is proposed and experimentally demonstrated, with reconfigurable capability by electronic control. A Mach-Zehnder modulator-based optical frequency comb (OFC) is used as an optical source, and its output is optically shaped before introducing a time delay by 70 km single-mode fiber (SMF) transmission. After an optical-to-electronic conversion, the frequency response in terms of central frequency and passband bandwidth can be electronically reconfigurable by varying either the input microwave frequency of the OFC or the waveshaper configuration without modification of the optical configuration. The experimental results show that more than a 35 dB out-of-band rejection ratio and at least a 3 GHz continuously tuning range of passband center frequency without any DC response can be successfully achieved.

  16. Spin-wave band-pass filters based on yttrium iron garnet films for tunable microwave photonic oscillators

    NASA Astrophysics Data System (ADS)

    Ustinov, A. B.; Drozdovskii, A. V.; Nikitin, A. A.; Kalinikos, B. A.

    2015-12-01

    The paper reports on development of tunable band-pass microwave filters for microwave photonic generators. The filters were fabricated with the use of epitaxial yttrium iron garnet films. Principle of operation of the filters was based on excitation, propagation, and reception of spin waves. In order to obtain narrow pass band, the filtering properties of excitation and reception antennas were exploited. The filters demonstrated insertion losses of 2-3 dB, bandwidth of 25-35 MHz, and tuning range of up to 1.5 GHz in the range 3-7 GHz.

  17. Bandwidth stretching in interdigital bandpass RF filter on silicon substrate using bulk micromachining

    NASA Astrophysics Data System (ADS)

    Bhadauria, Avanish; Jangid, Harsh Vardhan; Singh, Kulwant

    2016-03-01

    We first time proposed a new technique to strech the fractional bandwidth (FBW) of an interdigital bandpass RF filter (IDBPF) on a silicon substrate using MEMS based micromachining and studied its RF performance through a circuit model under micromachining. When a silicon substrate is selectively etched vertically beneath the coupled line resonators in IDBPF, a mixed air-silicon region is created inside the substrate. This mixed region manipulates the effective dielectric constant and electromagnetic coupling among resonators, which finally leads to a signifant change in FWB of filter. To study transmission properties under micromachining, a five pole IDBPF is designed on a 500 µm thick high resistivity silicon substrate centered at 5.00 GHz with FBW of 56.8% and simulated by FEM based electromagnetic software HFSS. It has been seen by simulation results that at 50% micromached height from the ground plane, the IDBPF has achieved a maximum FBW of 79.8%, which is difficult to realize in conventional IDBPF on same substrate due to requirement of very tight coupling. Finally, we have developed an equivalent circuit model and studied the variation of its electrical parameters under micromachining and RF performance of filter in terms of circuit components.

  18. Microwave Band-Pass Filter with Aerosol-Deposited Al2O3-Polytetrafluoroethylene Composite Thick Films.

    PubMed

    Lee, Ji-Won; Koh, Jung-Hyuk

    2015-03-01

    Fabrication of microwave band-pass filter with coplanar waveguide with ground structure was realized by employing Al2O3-polytetrafluoroethylene (Al2O3-PTFE) composite thick films for integrated substrates produced by aerosol deposition (AD). In order to predict the performance of the band-pass filter, 3-D electromagnetic simulations were performed by high-frequency structure analysis. The thick Al2O3-PTFE composite films prepared by the AD process had submicron-sized Al2O3 crystallites due to the shock-absorbing effect of PTFE during the film growth. The thick films were characterized by X-ray diffraction and scanning electron microscopy. The Cu transmission lines with the thickness of 300 nm were deposited by electron-beam evaporation to form the band-pass filter. The fabricated band-pass filter showed similar characteristics to the simulation results. The insertion loss and resonance frequency were 9.5 dB and 2.3 GHz, respectively. PMID:26413656

  19. Performance Enhancement of Tunable Bandpass Filters Using Selective Etched Ferroelectric Thin Films

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Mueller, Carl H.; VanKeuls, Fred W.; Subramanyam, Guru; Vignesparamoorthy, Sivaruban

    2003-01-01

    The inclusion of voltage-tunable barium strontium titanate (BSTO) thin films into planar band pass filters offers tremendous potential to increase their versatility. The ability to tune the passband so as to correct for minor deviations in manufacturing tolerances, or to completely reconfigure the operating frequencies of a microwave communication system, are highly sought-after goals. However, use of ferroelectric films in these devices results in higher dielectric losses, which in turn increase the insertion loss and decrease the quality factors of the filters. This study explores the use of patterned ferroelectric layers to minimize dielectric losses without degrading tunability. Patterning the ferroelectric layers enables us to constrict the width of the ferroelectric layers between the coupled microstrip lines, and minimize losses due to ferroelectric layers. Coupled one-pole microstrip bandpass filters with fundamental resonances at approx. 7.2 GHz and well defined harmonic resonances at approx. 14.4 and approx. 21.6 GHz, were designed, simulated and tested. For one of the filters, experimental results verified that its center frequency was tunable by 528 MHz at a center frequency of 21.957 GHz, with insertion losses varying from 4.3 to 2.5 dB, at 0 and 3.5 V/micron, respectively. These data demonstrate that the tuning-to-loss figure of merit of tunable microstrip filters can be greatly improved using patterned ferroelectric thin films as the tuning element, and tuning can be controlled by engineering the ferroelectric constriction in the coupled sections.

  20. All-optical microwave bandpass filter with negative coefficients based on a phase modulator and linearly chirped fiber Bragg gratings.

    PubMed

    Zeng, Fei; Wang, Jun; Yao, Jianping

    2005-09-01

    A novel all-optical microwave bandpass filter with negative coefficients is presented. Positive and negative coefficients are obtained through conversion from phase modulation to intensity modulation by passing the phase-modulated optical carriers through chirped fiber Bragg gratings having group-delay responses with positive and negative slopes. A two-tap transversal microwave filter with one negative coefficient is experimentally implemented. PMID:16190418

  1. Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal.

    PubMed

    Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

    2016-07-01

    A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application. PMID:27475583

  2. Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

    2016-07-01

    A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application.

  3. Application of Cu2O-doped phosphate glasses for bandpass filter

    NASA Astrophysics Data System (ADS)

    Elhaes, H.; Attallah, M.; Elbashar, Y.; El-Okr, M.; Ibrahim, M.

    2014-09-01

    Phosphate glasses doped with copper ions having general composition 42P2O5-39ZnO-(18-x) Na2O-1CaO-xCu2O [x=2, 4, 6, 8, 10 mol%] were prepared using a conventional melt-quench technique. Physical and chemical properties of the glasses were investigated using X-ray diffraction technique and UV-visible optical absorption. The density was measured by Archimedes' method, and molar volume (VM) was calculated. It is found that density and molar volume show opposite trend by increasing Cu2O content. Absorbance and transmittance at the normal incidence are measured by a spectrophotometer in the spectral range of 190-1100 nm. Analyses of the obtained results were considered in the frame of current theories. Absorption data were used for absorption coefficient, the optical band gap (Eopt), the cutoff in UV and IR bands to the bandpass filter, which confirmed the optical properties of this type of filter. Eopt values for different glass samples are found to decrease with increasing Cu2O content.

  4. A K-band Frequency Agile Microstrip Bandpass Filter using a Thin Film HTS/Ferroelectric/dielectric Multilayer Configuration

    NASA Technical Reports Server (NTRS)

    Subramanyam, Guru; VanKeuls, Fred; Miranda, Felix A.

    1998-01-01

    We report on YBa2Cu3O(7-delta) (YBCO) thin film/SrTiO3 (STO) thin film K-band tunable bandpass filters on LaAlO3 (LAO) dielectric substrates. The 2 pole filter has a center frequency of 19 GHz and a 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO(epsilon(sub rSTO). A large tunability ((Delta)f/f(sub 0) = (f(sub Vmax) - f(sub 0)/f(sub 0), where f(sub 0) is the center frequency of the filter at no bias and f(sub Vmax) is the center frequency of the filter at the maximum applied bias) of greater than 10% was obtained in YBCO/STO/LAO microstrip bandpass filters operating below 77 K. A center frequency shift of 2.3 GHz (i.e., a tunability factor of approximately 15%) was obtained at a 400 V bipolar dc bias, and 30 K, with minimal degradation in the insertion loss of the filter. This paper addresses design, fabrication and testing of tunable filters based on STO ferroelectric thin films. The performance of the YBCO/STO/LAO filters is compared to that of gold/STO/LAO counterparts.

  5. A Novel K-Band Tunable Microstrip Bandpass Filter Using a Thin Film HTS/Ferroelectric/ Dielectric Configuration

    NASA Technical Reports Server (NTRS)

    Subramanyam, G.; VanKeuls, F.; Miranda, F. A.

    1998-01-01

    We report on YBCO/strontium titanate (STO) thin film K-band tunable bandpass filters on lanthanum aluminate substrates. The 2 pole filters were designed for a center frequency of 19 GHz and 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO (epsilon-rSTO). Center frequency shifts greater than 2 GHz were obtained at a 400V bipolar dc bias at temperatures below 77K, with minimum degradation in the insertion loss of the filters.

  6. Integrated InP-InGaAsP tunable coupled ring optical bandpass filters with zero insertion loss.

    PubMed

    Guzzon, Robert S; Norberg, Erik J; Parker, John S; Johansson, Leif A; Coldren, Larry A

    2011-04-11

    Second and third-order monolithically integrated coupled ring bandpass filters are demonstrated in the InP-InGaAsP material system with active semiconductor optical amplifiers (SOAs) and current injection phase modulators (PMs). Such integration achieves a high level of tunability and precise generation of optical filters in the RF domain at telecom wavelengths while simultaneously compensating for device insertion loss. Passband bandwidth tunability of 3.9 GHz to 7.1 GHz and stopband extinction up to 40 dB are shown for third-order filters. Center frequency tunability over a full free spectral range (FSR) is demonstrated, allowing for the placement of a filter anywhere in the telecom C-band. A Z-transform representation of coupled resonator filters is derived and compared with experimental results. A theoretical description of filter tunability is presented. PMID:21503092

  7. Tin-polyimide and indium-polyimide thin-film composites as soft X-ray bandpass filters

    NASA Technical Reports Server (NTRS)

    Powell, Stephen F.; Allen, Maxwell J.; Willis, Thomas D.

    1993-01-01

    A tin-polyimide and an indium-polyimide soft X-ray bandpass filter were fabricated with thicknesses of 1400 and 1750 A for the metal and polyimide components, respectively. The transmission of each filter was measured at the Stanford Synchrotron Radiation Laboratory. The transmission of the tin-polyimide filter was found to be about 40 percent for radiation with wavelengths between 60 and 80 A. The transmission of the indium-polyimide filter was greater than 40 percent between 70 and 90 A. The indium was about 5 percent more transmissive than the tin and attained a maximum transmission of about 48 percent at 76 A. Such filters have potential applications to soft X-ray telescopes that operate in this region. They might also be of interest to investigators who work with X-ray microscopes that image live biological specimens in the 23-44-A water window.

  8. Development of simple band-spectral pyranometer and quantum meter using photovoltaic cells and bandpass filters

    NASA Astrophysics Data System (ADS)

    Bilguun, Amarsaikhan; Nakaso, Tetsushi; Harigai, Toru; Suda, Yoshiyuki; Takikawa, Hirofumi; Tanoue, Hideto

    2016-02-01

    In recent years, greenhouse automatic-control, based on the measurement of solar irradiance, has been attracting attention. This control is an effective method for improving crop production. In the agricultural field, it is necessary to measure Photon Flux Density (PFD), which is an important parameter in the promotion of plant growth. In particular, the PFD of Photosynthetically Active Radiation (PAR, 400-700 nm) and Plant Biologically Active Radiation (PBAR, 300-800 nm) have been discussed in agricultural plant science. The commercial quantum meter (QM, PAR meter) can only measure Photosynthetically Photon Flux Density (PPFD) which is the integrated PFD quantity on the PAR wavelength. In this research, a band-spectral pyranometer or quantum meter using PVs with optical bandpass filters for dividing the PBAR wavelength into 100 nm bands (five independent channels) was developed. Before field testing, calibration of the instruments was carried out using a solar simulator. Next, a field test was conducted in three differing weather conditions such as clear, partly cloudy and cloudy skies. As a result, it was found that the response rate of the developed pyranometer was faster by four seconds compared with the response rate of the commercial pyranometer. Moreover, the outputs of each channel in the developed pyranometer were very similar to the integrated outputs of the commercial spectroradiometer. It was confirmed that the solar irradiance could be measured in each band separately using the developed band-spectral pyranometer. It was indicated that the developed band-spectral pyranometer could also be used as a PV band-spectral quantum meter which is obtained by converting the band irradiance into band PFD.

  9. Ultra-compact UHF Band-pass Filter Designed by Archimedes Spiral Capacitor and Shorted-loaded Stubs

    NASA Astrophysics Data System (ADS)

    Peng, Lin; Jiang, Xing

    2015-01-01

    UHF microstrip band-pass filters (BPFs) that much smaller than the referred BPFs are proposed in this communication. For the designing purpose of compactness, archimedes spiral capacitor and ground-loaded stubs are utilized to enhance capacitances and inductance of a filter. Two compact BPFs denoted as BPF 1 and BPF 2 are designed by applying these techniques. The size of BPF 1 and BPF 2 are 0.062 λg × 0.056 λg and 0.047 λg × 0.043 λg, respectively, where λg are guided wavelengths of the centre frequencies of the corresponding filters. The proposed filters were constructed and measured, and the measured results are in good agreement with the simulated ones.

  10. Novel Compact Ultra-Wideband Bandpass Filter by Application of Short-Circuited Stubs and Stepped-Impedance-Resonator

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Ping; Ma, Zhewang; Anada, Tetsuo

    To realize the compact ultra-wideband (UWB) bandpass filters, a novel filter prototype with two short-circuited stubs loaded at both sides of a stepped-impedance resonator (SIR) via the parallel coupled lines is proposed based on a distributed filter synthesis theory. The equivalent circuit of this filter is established, while the corresponding 7-pole Chebyshev-type transfer function is derived for filter synthesis. Then, a distributed-circuit-based technique was presented to synthesize the elements' values of this filter. As an example, a FCC UWB filter with the fractional bandwidth (FWB) @ -10dB up to 110% was designed using the proposed prototype and then re-modeled by commercial microwave circuit simulator to verify the correctness and accuracy of the synthesis theory. Furthermore, in terms of EM simulator, the filter was further-optimized and experimentally-realized by using microstrip line. Good agreements between the measurement results and theoretical ones validate the effectiveness of our technique. In addition, compared with the conventional SIR-type UWB filter without short-circuited stubs, the new one significantly improves the selectivity and out-of-band characteristics (especially in lower one -45dB@1-2GHz) to satisfy the FCC's spectrum mask. The designed filter also exhibits very compact size, quite low insertion loss, steep skirts, flat group delay and the easily-fabricatable structure (the coupling gap dimension in this filter is 0.15mm) as well. Moreover, it should be noted that, in terms of the presented design technique, the proposed filter prototype can be also used to easily realize the UWB filters with other FBW even greater than 110%.

  11. A bandpass filter for the enhancement of an X-ray reconstruction of the tissue in the spinal canal

    NASA Technical Reports Server (NTRS)

    Reed, I. S.; Glenn, W. V.; Kwoh, Y. S.; Truong, T. K.

    1980-01-01

    In this communication, a new bandpass reconstruction filter is developed to partially remove the low spatial frequencies of the bone and the soft tissue in an X-ray reconstruction of a lumbar spine. This partial removal of the low frequencies suppresses the bony vertebral body and the soft tissue components within the projections of actual clinical data. It also has the effect of enhancing the sharp edges of the fatty tissue surrounding the spinal cord region. The intent of this effort is to directly visualize the spinal cord without the need for water-soluble contrast (e.g., metrizamide) to be installed through lumbar punctures.

  12. A substrate integrated folded waveguide (SIFW) H-plane band-pass filter with double H-plane septa based on LTCC.

    PubMed

    Wang, Zhengwei; Bu, Shirong; Luo, Zhengxiang

    2012-03-01

    In this paper, a novel substrate integrated folded waveguide (SIFW) H-plane band-pass filter based on low-temperature co-fired ceramic technology (LTCC) is proposed which employs double H-plane septa of a short-ended evanescent waveguide as an impedance inverter. The filter has advantages of convenient integration, compact, low cost, mass-producibility, and ease of fabrication, and it also has frequency responses similar to those of traditional E-plane double-iris waveguide band-pass filters. To validate the new proposed topology, a three-pole narrowband band-pass filter is designed and fabricated using half-wavelength resonators. A comparison between measured results and simulated results shows good agreement. PMID:22481793

  13. HTS Dual-band Bandpass Filter Using Stub-loaded Hair-pin Resonators with Independently Controllable Bandwidths

    NASA Astrophysics Data System (ADS)

    Sekiya, N.; Sugiyama, S.

    We have developed a high-temperature superconducting (HTS) dual-band bandpass filter (BPF) using stub-loaded hair-pin resonators with independently controllable bandwidths. The proposed dual-band BPF is composed of five stub-loaded hair-pin resonators with H-shaped waveguides placed at the center in the spaces between them. The resonator enables independent control of the first and second band resonant frequencies. The main advantage of the proposed filter was to enable independent control of the bandwidths of the first and second band. The coupling coefficient of the second one was controlled by the distance between the resonators, which did not affect the coupling coefficient of the first one. On the other hand, the coupling coefficient of the first one was controlled by the H-shaped waveguide, which did not affect the coupling coefficient of the secondone. An electromagnetic simulator was used to design and analyze the filter. The filter was designed at 3.5 GHz with a 70-MHz (2%) bandwidth for the first band and at 5.0 GHz with a 250-MHz (5%) bandwidth for the second band. The filter was fabricated using YBa2Cu3Oy thin film on a CeO2-bufferd Al2O3 substrate. The measured results agree well with the simulated ones.

  14. Study of SNS and SIS NbN Josephson junctions coupled to a microwave band-pass filter

    NASA Astrophysics Data System (ADS)

    Baggetta, E.; Setzu, R.; Villégier, J. C.

    2006-06-01

    We have fabricated both NbN/TaxN/NbN SN*S-type, NbN/MgO/NbN SIS-type Josephson junctions and microwave band-pass filters on different substrates (Si, Sapphire, MgO). NbN films have been deposited on both sides of (100) oriented, 250 µm thick, MgO substrates with a high crystalline texture quality. The aim was to investigate the performances and the maximum achievable operating frequency in an NbN based RSFQ modulator front-end of an ADC in the 4 K-10 K temperature range. We observed that TaxN thin films can be tuned from an insulating phase to a superconducting phase (Tc ~4K) by varying the nitrogen content during sputter deposition while the barrier height of MgO can also be controlled by deposition conditions and by tri-layer postdeposition annealing. Junction properties (Jc~10-25 kA/cm2), Mac Cumber parameter and RnIc product measured up to 1 mV are shown to be controlled by the reactive sputtering conditions. We have designed three pole band-pass filters and resonators in a micro-strip configuration and studied the junction coupling with the filters. We will show that a sigma-delta NbN technology is a suitable solution for analogue-to-digital conversion in the future generations of telecommunication satellites to achieve high sampling frequency and large bandwidth at high carrier frequency signal.

  15. The enlargement of high reflectance range in ultra-narrow bandpass filter with disordered one-dimensional photonic crystal

    SciTech Connect

    Chen, Guibin; Yu, Haichun

    2014-01-21

    The conventional ultra-narrow bandpass filter structure has only a very limited width of high-reflectance range. This study, by introducing disorder into one-dimensional (1D) photonic crystal, attempts to enlarge the width of high-reflectance range while keeping the ultra-narrow bandpass. Enlargement by 46.8% was obtained after theoretical design. Since this structure contains some degree of disorder already, it has a strong tolerance of the variation of layer thicknesses. Unlike studies using conventional periodic structures, theoretical statistical results in this study demonstrate that high quality remains even after allowing for ±5% variation of layer thicknesses. This indicates that only a very low thickness control precision is required in the future and the production difficulty is immensely lowered. To put the construction to test, a structure has been developed and demonstrated by a magnetron reactive sputtering coating system, which agrees with the theoretical result very well. By introducing disorder into the periodic 1D photonic crystal structure, the high-reflectance range is significantly extended by 37%, with an ultra-narrow pass band of 0.8 nm and intensity of 82%.

  16. A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters.

    PubMed

    Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

    2015-01-01

    We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies. PMID:26552584

  17. A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

    2015-11-01

    We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies.

  18. A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters

    PubMed Central

    Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

    2015-01-01

    We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies. PMID:26552584

  19. Miniature bandpass microwave filter with interference suppression by more than 100 dB in a wide rejection band

    NASA Astrophysics Data System (ADS)

    Belyaev, B. A.; Serzhantov, A. M.; Tyurnev, V. V.; Leksikov, A. A.; Bal'va, Ya. F.

    2013-08-01

    A new planar resonator design in which a single conductor is replaced by three parallel stripe conductors located one above the other on a suspended two-layer substrate is proposed. It is shown that the resonator longitudinal sizes can be significantly reduced and, at the same time, the resonator intrinsic Q factor and frequencies of higher oscillation modes can be increased. A fourth-order bandpass filter with a central frequency of the transmission band (relative width 5%) of 1 GHz has been developed and fabricated. This filter has a -100-dB rejection band up to frequencies exceeding 10 GHz. The filter is enclosed in a metallic case with an internal size of 38 × 12 × 7.5 mm. It is shown that a similar filter fabricated in accordance with low-temperature cofired ceramic (LTCC) technology has a -40-dB rejection band up to 30 GHz, with sizes reduced to 5.0 × 4.25 × 1.24 mm.

  20. Tailoring the time delay of optical pulse/sequence employing cascaded SOA and band-pass filter

    NASA Astrophysics Data System (ADS)

    Wang, Fu; Wang, Zhi; Wu, Chongqing; Mao, Yaya; Shang, Chao; Gao, Kaiqiang; Li, Qiang

    2016-06-01

    A tunable time delay for a 100-ps pulse is achieved via a SOA cascaded band-pass filter, which can be tailored by tuning the filter or changing the SOA injection current. For a single pulse, when the pulse propagates through the cascaded system, a delay of 99.6 ps and an advance of 42.6 ps can be achieved by altering the SOA injection current at two different wavelengths located in the red band and blue band of the filter, respectively. The corresponding tunable delay range is 165 ps, and the maximum delay-bandwidth product (DBP) is 1.65. For an optical sequence, to our knowledge, it is the first time that the time delay is tailored over 145.6 ps corresponding to a DBP of 1.46 by tuning the wavelength from 1556.075 to 1556.955 nm, and 45.2 ps (95.6 ps) advance (delay) by tuning the injection current from 100 to 500 mA at 1556.155 nm (1556.955 nm). The dependence of the time delay on the injection current and filtering configuration has been discussed based on plenty of experiments data. Based on SOA's fast switching, this device can be used for signal synchronization and bit-by-bit signal processing in a communication system.

  1. Tunable photonic filters: a digital signal processing design approach.

    PubMed

    Binh, Le Nguyen

    2009-05-20

    Digital signal processing techniques are used for synthesizing tunable optical filters with variable bandwidth and centered reference frequency including the tunability of the low-pass, high-pass, bandpass, and bandstop optical filters. Potential applications of such filters are discussed, and the design techniques and properties of recursive digital filters are outlined. The basic filter structures, namely, the first-order all-pole optical filter (FOAPOF) and the first-order all-zero optical filter (FOAZOF), are described, and finally the design process of tunable optical filters and the designs of the second-order Butterworth low-pass, high-pass, bandpass, and bandstop tunable optical filters are presented. Indeed, we identify that the all-zero and all-pole networks are equivalent with well known principles of optics of interference and resonance, respectively. It is thus very straightforward to implement tunable optical filters, which is a unique feature. PMID:19458728

  2. A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters

    PubMed Central

    Li, Hanlun; Zhang, Aiwu; Hu, Shaoxing

    2015-01-01

    This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels. PMID:26205264

  3. Multilayer micromachined bandpass filter for L/S band satellite communication systems

    NASA Astrophysics Data System (ADS)

    Qureshi, A. Q. A.; Pelliccia, L.; Colpo, S.; Iannacci, J.; Farinelli, P.; Margesin, B.

    2013-05-01

    This paper presents the design and fabrication of a 2nd order L/S band filter used as a test vehicle for the development of a fabrication technology for cavity microwave filters based on micromachining in order to preliminary explore all the technological constraints on a simpler structure. The multilayered 2nd order pseudo-elliptic L/S band filter is based on λ/4 TEM mode resonators which are patterned on a dielectric layer. For convenience 500 μm thick Si wafers have been used even if this limits the simulated Q factor of the 2nd order L/S band filter to about 200. The test structures presented here amount to the more sophisticated 4th order filters in an extended technological concept (i.e. 1500 μm thick Si wafer and two additional modules) but still based on similar resonating elements aiming to replace the existing bulky metallic waveguide filters installed in many satellite transceivers. A five mask fabrication process is employed for the realization of the elements of said filter which is based on three modules. Module A and B are fabricated on the same wafer while module C which served as ground is fabricated on a separate wafer. A 2 μm high sealing ring is etched on the back of module A and B by DRIE (Deep Reactive Ion Etching) while cavities and TSVs (Through Silicon Vias) are etched by TMAH (TetraMethylAmmonium Hydroxide). The surface mounting compatibility of the filter is obtained by adopting vertical via holes to connect the external feeding lines (e.g. microstrip or coplanar) with the filter resonators. Such a transition separates the input/output from the filter input/output coupling mechanism. The final wafers are diced and specimens are vertically stacked and bonded through thermocompression bonding. The overall filter dimensions are 48x20x1.5 mm3.

  4. Spoof surface plasmon-based bandpass filter with extremely wide upper stopband

    NASA Astrophysics Data System (ADS)

    Xiaoyong, Liu; Lei, Zhu; Yijun, Feng

    2016-03-01

    We investigate the guiding modes of spoof surface plasmon polaritons (SPPs) on a symmetric ultra-thin plasmonic structure. From the analysis, we deduce the operating frequency region of the single-mode propagation. Based on this property, a spoof SPPs lowpass filter is then constituted in the microwave frequency. By introducing a transmission zero at the lower frequency band using a pair of stepped-impedance stubs, a wide passband filter is further realized. The proposed filter is fed by a transducer composed of a microstrip line with a flaring ground. The simulated results show that the presented filter has an extremely wide upper stopband in addition to excellent passband filtering characteristics such as low loss, wide band, and high square ratio. A prototype passband filter is also fabricated to validate the predicted performances. The proposed spoof-SPPs filter is believed to be very promising for other surface waveguide components in microwave and terahertz bands. Project supported by the Key Grant Project of Ministry of Education of China (Grant No. 313029), the FDCT Research Grant from Macao Science and Technology Development Fund, China (Grant No. 051/2014/A1), and the Multi-Year Research Grant from University of Macau, Macau SAR, China (Grant No. MYRG2014-00079-FST).

  5. Active tuning of a microstrip hairpin-line microwave bandpass filter on a polycrystalline yttrium iron garnet substrate using small magnetic fields

    NASA Astrophysics Data System (ADS)

    Gillette, S. M.; Geiler, A. L.; Chen, Z.; Chen, Y.; Arruda, T.; Xie, C.; Wang, L.; Zhu, X.; Liu, M.; Mukerjee, S.; Vittoria, C.; Harris, V. G.

    2011-04-01

    Active magnetic tuning of a microstrip hairpin-line coupled resonator bandpass filter fabricated on a polycrystalline yttrium iron garnet substrate has been demonstrated. The filter exhibits a five-pole Chebyshev response with passband center frequency tunability from 8.3 to 9 GHz under low applied H fields of 50-200 Oe. The instantaneous bandwidth was measured to be approximately 1 GHz. During tuning, passband center frequency insertion loss varies between 1 and 1.4 dB. Good agreement between simulated and measured device performance was demonstrated. Advantages of the proposed filter design include planar geometry, compact size, low insertion loss, and low field tunability. The proposed design approach lends itself to the implementation of a wide range of filter responses, including low pass, high pass, bandpass, and band stop, as well as passband characteristics, including center frequency, fractional bandwidth, passband ripple, out-of-band rejection, etc.

  6. "The Design of a Compact, Wide Spurious-Suppression Bandwidth Bandpass Filter Using Stepped Impedance Resonators"

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop; Wollack, Edward J.; Doiron, Terence; Papapolymerou, John; Laskar, Joy

    2005-01-01

    We propose an analytical design for a microstrip broadband spurious-suppression filter. The proposed design uses every section of the transmission lines as both a coupling and a spurious suppression element, which creates a very compact, planar filter. While a traditional filter length is greater than the multiple of the quarter wavelength at the center passband frequency (lambda(sub g)/4), the proposed filter length is less than (order n(Ssup th) + l)center dot lambda(sub g)/8. The filter s spurious response and physical dimension are controlled by the step impedance ratio (R) between two transmission line sections as a lambda(sub g)/4 resonator. The experimental result shows that, with R of 0.2, the out-of-band attenuation is greater than 40 dB; and the first spurious mode is shifted to more than 5 times the fundamental frequency. Moreover, it is the most compact planar filter design to date. The results also indicate a low in-band insertion loss.

  7. Design of high-order HTS dual-band bandpass filters with receiver subsystem for future mobile communication systems

    NASA Astrophysics Data System (ADS)

    Sekiya, N.

    2016-08-01

    We have developed two high-order high-temperature superconducting (HTS) dual-band bandpass filters (BPFs) with a receiver subsystem for future mobile communication systems. They feature stub-loaded hair-pin resonators with two types of microstrip lines between them. One has a six-pole design, and the other has an eight-pole design. Both were designed to operate at 2.15 GHz with a 43-MHz (2%) bandwidth for the lower passband and at 3.50 GHz with a 70-MHz (2%) bandwidth for the upper one. They were fabricated using YBa2Cu3Oy thin film on a CeO2-bufferd r-Al2O3 substrate. The measured results for both filters agree well with the simulated ones. The HTS dual-band BPF receiver subsystem uses a pulse tube cryocooler and a wideband low noise amplifier (LNA). We measured the frequency response of the six-pole dual-band BPF with and without a wideband LNA with a gain of 10 dB. The measured return losses were close.

  8. A Dual-Mode Bandpass Filter with Multiple Controllable Transmission-Zeros Using T-Shaped Stub-Loaded Resonators

    PubMed Central

    Yao, Zh.; Wang, C.; Kim, N. Y.

    2014-01-01

    A dual-mode broadband bandpass filter (BPF) with multiple controllable transmission-zeros using T-shaped stub-loaded resonators (TSSLRs) is presented. Due to the symmetrical plane, the odd-even-mode theory can be adopted to characterize the BPF. The proposed filter consists of a dual-mode TSSLR and two modified feed-lines, which introduce two capacitive and inductive source-load (S-L) couplings. Five controllable transmission zeros (TZs) can be achieved for the high selectivity and the wide stopband because of the tunable amount of coupling capacitance and inductance. The center frequency of the proposed BPF is 5.8 GHz, with a 3 dB fraction bandwidth of 8.9%. The measured insertion and return losses are 1.75 and 28.18 dB, respectively. A compact size and second harmonic frequency suppression can be obtained by the proposed BPF with S-L couplings. PMID:24688406

  9. Optimization of excitation-emission band-pass filter for visualization of viable bacteria distribution on the surface of pork meat.

    PubMed

    Nishino, Ken; Nakamura, Kazuaki; Tsuta, Mizuki; Yoshimura, Masatoshi; Sugiyama, Junichi; Nakauchi, Shigeki

    2013-05-20

    A novel method of optically reducing the dimensionality of an excitation-emission matrix (EEM) by optimizing the excitation and emission band-pass filters was proposed and applied to the visualization of viable bacteria on pork. Filters were designed theoretically using an EEM data set for evaluating colony-forming units on pork samples assuming signal-to-noise ratios of 100, 316, or 1000. These filters were evaluated using newly measured EEM images. The filters designed for S/N = 100 performed the best and allowed the visualization of viable bacteria distributions. The proposed method is expected to be a breakthrough in the application of EEM imaging. PMID:23736477

  10. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    SciTech Connect

    Yan, Hai Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  11. Dual-band bandpass terahertz wave filter based on microstrip resonant structure

    NASA Astrophysics Data System (ADS)

    Liu, Yu-hang; Li, Jiu-sheng

    2011-11-01

    The terahertz (THz) band, which refers to the spectral region between 0.1 and 10THz, covers the fingerprints of many chemical and biological materials. Within the past few years, there are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, chemical and biological sensing, terahertz wave communications, and medical diagnostics. For potential applications, the functional devices, such as beam polarizers, switchs and filters, are crucial components for a terahertz system. Terahertz wave filter based on two kinds of microstrip resonant structures, has been characterized by terahertz time-domain spectroscopy in the region from 0.1 to 3THz. The experimental results for the frequency dependence of the transmittance of the terahertz wave filter show that the terahertz wave transmittance peak is of 79.5% at 0.5THz and 82.5% at 0.81THz.

  12. Dual-band bandpass terahertz wave filter based on microstrip resonant structure

    NASA Astrophysics Data System (ADS)

    Liu, Yu-hang; Li, Jiu-sheng

    2012-03-01

    The terahertz (THz) band, which refers to the spectral region between 0.1 and 10THz, covers the fingerprints of many chemical and biological materials. Within the past few years, there are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, chemical and biological sensing, terahertz wave communications, and medical diagnostics. For potential applications, the functional devices, such as beam polarizers, switchs and filters, are crucial components for a terahertz system. Terahertz wave filter based on two kinds of microstrip resonant structures, has been characterized by terahertz time-domain spectroscopy in the region from 0.1 to 3THz. The experimental results for the frequency dependence of the transmittance of the terahertz wave filter show that the terahertz wave transmittance peak is of 79.5% at 0.5THz and 82.5% at 0.81THz.

  13. Micro-electro-mechanical bandpass filters for signal processing by standard CMOS process

    NASA Astrophysics Data System (ADS)

    Huang, Tsungwei; Chang, Peizen; Lee, ChiYuan; Xiao, Fuyuan

    2000-06-01

    This investigation fabricates a laminated-suspension microelectromechanical filter by a fully compatible CMOS process. Experimentally, due to the top metal layer begin used as the etch-resistant mask during the subsequent dry etching. Therefore, this study performs maskless etching with plasma and obtains excellent result including high selectivity and full release of the structure. Additionally, the MEMS filter can be driven by applying low-voltage of around 5 volts and a measured center frequency of around 13.1kHz and a quality factor of around 1871 were obtained for a single-comb resonator operate din air. The filter proposed herein has a monolithic integration capability with the relative electric circuits.

  14. Substrate integrated waveguide (SIW) inductive window band-pass filter based on post-wall irises

    NASA Astrophysics Data System (ADS)

    Nouri, K.; Haddadi, K.; Benzaïm, O.; Lasri, T.; Feham, M.

    2011-03-01

    In this article, we demonstrate a new inductive-window 5.245-GHz-band-pass filter based on post-wall irises by standard PcB process on Epoxy FR4 substrate. A new and easy to build microstrip-to-waveguide transition that consists of three tapers is also designed to connect the filter to standard measurement system. Both simulated results and measurements have shown insertion-loss lower than 5 dB within 14% bandwidth around 5.245 GHz and input return loss better than 25 dB over the frequency range.

  15. Systematic studies of the effect of a bandpass filter on a Josephson-junction noise thermometer

    SciTech Connect

    Soulen, R.J. Jr. ); Fogle, W.E.; Colwell, J.H. )

    1991-03-01

    This paper present the results of an extensive study of the effect of a filter upon the performance of a resistive SQUID noise thermometer used to define an absolute temperature scale below 1 K. Agreement between the model for this effect and the experimental results indicated that the temperature scale defined by the noise thermometer is accurate to 0.1%.

  16. A multiband THz bandpass filter based on multiple-resonance excitation of a composite metamaterial

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Fan, Wen-Hui

    2015-05-01

    We present a systematic numerical study on a metal-dielectric-metal (MDM) sandwich structure for multiple resonance transmission in terahertz (THz) region. The designed structure consists of periodic square close ring array on both side of a flexible dielectric substrate, exhibits a multiband transmission, with low average insertion loss, steep skirts and high out-of-band rejection. In addition, due to its rotationally symmetric structure, this filter is polarization-insensitive for normal incidence of the electromagnetic waves, keeping highly transmission at a wide range of incident angles for transverse electric waves and transverse magnetic waves. The metamaterial structure can be utilized as a desirable multiband filter with many practical applications, especially for THz communication, spectroscopic detection and phase imaging.

  17. The role of excitation-pattern cues in the detection of frequency shifts in bandpass-filtered complex tones.

    PubMed

    Marmel, Frederic; Plack, Christopher J; Hopkins, Kathryn; Carlyon, Robert P; Gockel, Hedwig E; Moore, Brian C J

    2015-05-01

    One task intended to measure sensitivity to temporal fine structure (TFS) involves the discrimination of a harmonic complex tone from a tone in which all harmonics are shifted upwards by the same amount in hertz. Both tones are passed through a fixed bandpass filter centered on the high harmonics to reduce the availability of excitation-pattern cues and a background noise is used to mask combination tones. The role of frequency selectivity in this "TFS1" task was investigated by varying level. Experiment 1 showed that listeners performed more poorly at a high level than at a low level. Experiment 2 included intermediate levels and showed that performance deteriorated for levels above about 57 dB sound pressure level. Experiment 3 estimated the magnitude of excitation-pattern cues from the variation in forward masking of a pure tone as a function of frequency shift in the complex tones. There was negligible variation, except for the lowest level used. The results indicate that the changes in excitation level at threshold for the TFS1 task would be too small to be usable. The results are consistent with the TFS1 task being performed using TFS cues, and with frequency selectivity having an indirect effect on performance via its influence on TFS cues. PMID:25994700

  18. U and Pu Gamma-Ray Measurements of Spent Fuel Using a Gamma-Ray Mirror Band-Pass Filter

    SciTech Connect

    Ziock, Klaus-Peter; Alameda, J.B.; Brejnholt, N.F.; Decker, T.A.; Descalle, M.A.; Fernandez-Perea, M.; Hill, R.M.; Kisner, R.A.; Melin, A.M.; Patton, B.W.; Ruz, J.; Soufli, R.; Pivovaroff, M.J.

    2014-01-01

    Abstract. We report on the use of grazing incidence gamma-ray mirrors to serve as a narrow band-pass filter for advanced non-destructive analysis (NDA) of spent nuclear fuel. The purpose of the mirrors is to limit the radiation reaching a HPGe detector to narrow spectral bands around characteristic emission lines from fissile isotopes in the fuel. This overcomes the normal rate issues when performing gamma-ray NDA measurements. In a proof-of-concept experiment, a set of simple flat gamma-ray mirrors were used to directly observe the atomic florescence lines from U and Pu from spent fuel pins with the detector located in a shirt-sleeve environment. The mirrors, consisting of highly polished silicon substrates deposited with WC/SiC multilayer coatings, successfully deflected the lines of interest while the intense primary radiation beam from the fuel was blocked by a lead beam stop. The gamma-ray multilayer coatings that make the mirrors work at the gamma-ray energies used here (~ 100 keV) have been experimentally tested at energies as high as 645 keV, indicating that direct observation of nuclear emission lines from 239Pu should be possible with an appropriately designed optic and shielding configuration.

  19. Reduction of timing jitter and intensity noise in normal-dispersion passively mode-locked fiber lasers by narrow band-pass filtering.

    PubMed

    Qin, Peng; Song, Youjian; Kim, Hyoji; Shin, Junho; Kwon, Dohyeon; Hu, Minglie; Wang, Chingyue; Kim, Jungwon

    2014-11-17

    Fiber lasers mode-locked with normal cavity dispersion have recently attracted great attention due to large output pulse energy and femtosecond pulse duration. Here we accurately characterized the timing jitter of normal-dispersion fiber lasers using a balanced cross-correlation method. The timing jitter characterization experiments show that the timing jitter of normal-dispersion mode-locked fiber lasers can be significantly reduced by using narrow band-pass filtering (e.g., 7-nm bandwidth filtering in this work). We further identify that the timing jitter of the fiber laser is confined in a limited range, which is almost independent of cavity dispersion map due to the amplifier-similariton formation by insertion of the narrow bandpass filter. The lowest observed timing jitter reaches 0.57 fs (rms) integrated from 10 kHz to 10 MHz Fourier frequency. The rms relative intensity noise (RIN) is also reduced from 0.37% to 0.02% (integrated from 1 kHz to 5 MHz Fourier frequency) by the insertion of narrow band-pass filter. PMID:25402069

  20. An antenna-coupled bolometer with an integrated microstrip bandpass filter

    NASA Astrophysics Data System (ADS)

    Myers, Michael J.; Holzapfel, William; Lee, Adrian T.; O'Brient, Roger; Richards, P. L.; Tran, Huan T.; Ade, Peter; Engargiola, Greg; Smith, Andy; Spieler, Helmuth

    2005-03-01

    We describe the fabrication and testing of antenna-coupled superconducting transition-edge bolometers for use at millimeter wavelengths. The design uses a double-slot dipole antenna connected to superconducting niobium microstrip. Band defining filters are implemented in the microstrip, which is then terminated with a load resistor. The power dissipated in the load resistor is measured by a superconducting transition-edge sensor (TES). The load resistor and TES are thermally well connected and are supported by a silicon nitride substrate. The substrate is suspended by four narrow silicon nitride legs for thermal isolation. The bolometers have been optically characterized and the spectral response is presented. This detector is a prototype element for use in an array designed for studies of the cosmic microwave background polarization.

  1. A 1microW 85nV/ radicalHz pseudo open-loop preamplifier with programmable band-pass filter for neural interface system.

    PubMed

    Chang, Sun-Il; Yoon, Euisik

    2009-01-01

    We report an energy efficient pseudo open-loop amplifier with programmable band-pass filter developed for neural interface systems. The proposed amplifier consumes 400nA at 2.5V power supply. The measured thermal noise level is 85nV/ radicalHz and input-referred noise is 1.69microV(rms) from 0.3Hz to 1 kHz. The amplifier has a noise efficiency factor of 2.43, the lowest in the differential topologies reported up to date to our knowledge. By programming the switched-capacitor frequency and bias current, we could control the bandwidth of the preamplifier from 138 mHz to 2.2 kHz to meet various application requirements. The entire preamplifier including band-pass filters has been realized in a small area of 0.043mm(2) using a 0.25microm CMOS technology. PMID:19964762

  2. Insertion loss and noise-temperature contribution of high-temperature superconducting bandpass filters centered at 2.3 and 8.45 GHz

    NASA Technical Reports Server (NTRS)

    Prater, J. L.; Bautista, J. J.

    1993-01-01

    Two superconducting Tl-Ca-Cu-Ba-O bandpass filters were fabricated for JPL by Superconductor Technologies Incorporated, Santa Barbara, California. The filters were designed to operate at 2.3 GHz (S-band) with a 0.5-dB bandwidth of 60 MHz and at 8.45 GHz (X-band) with a 0.5-dB bandwidth of 150 MHz. The structure selected for both filters incorporates half-wavelength thin-film resonators in a stripline configuration. The S-band filter uses an edge-coupled interdigital design and the X-band filter uses an end-coupled design. The insertion loss and the noise-temperature contribution were measured at 12 K for both filters.

  3. Emergence of band-pass filtering through adaptive spiking in the owl's cochlear nucleus.

    PubMed

    Fontaine, Bertrand; MacLeod, Katrina M; Lubejko, Susan T; Steinberg, Louisa J; Köppl, Christine; Peña, Jose L

    2014-07-15

    In the visual, auditory, and electrosensory modalities, stimuli are defined by first- and second-order attributes. The fast time-pressure signal of a sound, a first-order attribute, is important, for instance, in sound localization and pitch perception, while its slow amplitude-modulated envelope, a second-order attribute, can be used for sound recognition. Ascending the auditory pathway from ear to midbrain, neurons increasingly show a preference for the envelope and are most sensitive to particular envelope modulation frequencies, a tuning considered important for encoding sound identity. The level at which this tuning property emerges along the pathway varies across species, and the mechanism of how this occurs is a matter of debate. In this paper, we target the transition between auditory nerve fibers and the cochlear nucleus angularis (NA). While the owl's auditory nerve fibers simultaneously encode the fast and slow attributes of a sound, one synapse further, NA neurons encode the envelope more efficiently than the auditory nerve. Using in vivo and in vitro electrophysiology and computational analysis, we show that a single-cell mechanism inducing spike threshold adaptation can explain the difference in neural filtering between the two areas. We show that spike threshold adaptation can explain the increased selectivity to modulation frequency, as input level increases in NA. These results demonstrate that a spike generation nonlinearity can modulate the tuning to second-order stimulus features, without invoking network or synaptic mechanisms. PMID:24790170

  4. Emergence of band-pass filtering through adaptive spiking in the owl's cochlear nucleus

    PubMed Central

    MacLeod, Katrina M.; Lubejko, Susan T.; Steinberg, Louisa J.; Köppl, Christine; Peña, Jose L.

    2014-01-01

    In the visual, auditory, and electrosensory modalities, stimuli are defined by first- and second-order attributes. The fast time-pressure signal of a sound, a first-order attribute, is important, for instance, in sound localization and pitch perception, while its slow amplitude-modulated envelope, a second-order attribute, can be used for sound recognition. Ascending the auditory pathway from ear to midbrain, neurons increasingly show a preference for the envelope and are most sensitive to particular envelope modulation frequencies, a tuning considered important for encoding sound identity. The level at which this tuning property emerges along the pathway varies across species, and the mechanism of how this occurs is a matter of debate. In this paper, we target the transition between auditory nerve fibers and the cochlear nucleus angularis (NA). While the owl's auditory nerve fibers simultaneously encode the fast and slow attributes of a sound, one synapse further, NA neurons encode the envelope more efficiently than the auditory nerve. Using in vivo and in vitro electrophysiology and computational analysis, we show that a single-cell mechanism inducing spike threshold adaptation can explain the difference in neural filtering between the two areas. We show that spike threshold adaptation can explain the increased selectivity to modulation frequency, as input level increases in NA. These results demonstrate that a spike generation nonlinearity can modulate the tuning to second-order stimulus features, without invoking network or synaptic mechanisms. PMID:24790170

  5. A Triple-band Bandpass Filter using Tri-section Step-impedance and Capacitively Loaded Step-impedance Resonators for GSM, WiMAX, and WLAN systems

    NASA Astrophysics Data System (ADS)

    Chomtong, P.; Akkaraekthalin, P.

    2014-05-01

    This paper presents a triple-band bandpass filter for applications of GSM, WiMAX, and WLAN systems. The proposed filter comprises of the tri-section step-impedance and capacitively loaded step-impedance resonators, which are combined using the cross coupling technique. Additionally, tapered lines are used to connect at both ports of the filter in order to enhance matching for the tri-band resonant frequencies. The filter can operate at the resonant frequencies of 1.8 GHz, 3.7 GHz, and 5.5 GHz. At resonant frequencies, the measured values of S11 are -17.2 dB, -33.6 dB, and -17.9 dB, while the measured values of S21 are -2.23 dB, -2.98 dB, and -3.31 dB, respectively. Moreover, the presented filter has compact size compared with the conventional open-loop cross coupling triple band bandpass filters

  6. Design and fabrication of UV band-pass filters based on SiO2/Si3N4 dielectric distributed bragg reflectors

    NASA Astrophysics Data System (ADS)

    Dai, Jiangping; Gao, Wang; Liu, Bin; Cao, Xianlei; Tao, Tao; Xie, Zili; Zhao, Hong; Chen, Dunjun; Ping, Han; Zhang, Rong

    2016-02-01

    We have designed one kind of optical filters based on double stacks of 13.5-pairs SiO2/Si3N4 dielectric distributed Bragg reflector (DDBR) structures, to realize the passband with different central wavelengths in ultraviolet (UV) range. These SiO2/Si3N4 multi-layers have been successfully fabricated on (0001) sapphire substrates by plasma-enhanced chemical vapor deposition (PECVD). The reflectance spectra measured by the UV-visible spectrometer manifest that a series of band-pass filters with fixed passband width of ∼30 nm and central passband varied from 310 nm to 370 nm have been obtained successfully. Besides, the other series of filters with passband width varied from 30 nm to 45 nm can be achieved. With good control of PECVD deposition parameters, all samples exhibit smooth surface with root mean square roughness less than 4.5 nm. Moreover, cross-section scanning electron microscope (SEM) images show these DDBR structures have good periodicity in accordance with the design, indicating that these band-pass filter structures are suitable for wavelength-window-selection UV photodetectors.

  7. A compact, higher order, high temperature superconductor microstrip bandpass filter on a two-inch lanthanum aluminate substrate for personal communication service applications

    NASA Astrophysics Data System (ADS)

    Pal, Srikanta; Stevens, Chris; Edwards, David

    2005-10-01

    A practical design methodology for a compact parallel-coupled microstrip bandpass filter structure with steep attenuation is introduced using a computer-aided full wave electromagnetic simulation based on the method of moments. The structure consists of an array of fully aligned half-wavelength spiral meander line resonators. Aimed at application in the front-end receiver of digital cellular communication service, a 12-pole high temperature superconductor filter with 2.27% fractional bandwidth at 883.0 MHz was designed. The filter is fabricated using thallium-barium-calcium-copper oxide (TBCCO) thin films on a two-inch lanthanum aluminate (LaAlO3) wafer. The S-parameter measurements show a good agreement with the simulated results. At 70 K, the 12-pole filter shows less than 0.4 dB insertion loss, 0.3 dB passband ripple, better than 12 dB return loss. The out of band rejection at 3 MHz below the passband edges is more than 60.0 dB. In order to estimate the power handling capability of the filter, the third-order intermodulation distortion was measured. A sensitivity analysis for the observed frequency shift in the filter is reported. Also from this analysis an approach for using the same design in 0.5% FBW applications is discussed.

  8. Combination of highly nonlinear fiber, an optical bandpass filter, and a Fabry-Perot filter to improve the signal-to-noise ratio of a supercontinuum continuous-wave optical source

    NASA Astrophysics Data System (ADS)

    Nan, Yinbo; Huo, Li; Lou, Caiyun

    2005-05-01

    We present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented. Numerical simulations show that the improvement in modulation depth is relative to the HNLF's length, the 3-dB bandwidth of the optical bandpass filter, and the reflection ratio of the FP filter and that the average improvement in modulation depth is 13.7 dB under specified conditions.

  9. Combination of highly nonlinear fiber, an optical bandpass filter, and a Fabry-Perot filter to improve the signal-to-noise ratio of a supercontinuum continuous-wave optical source.

    PubMed

    Nan, Yinbo; Huo, Li; Lou, Caiyun

    2005-05-20

    We present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented. Numerical simulations show that the improvement in modulation depth is relative to the HNLF's length, the 3-dB bandwidth of the optical bandpass filter, and the reflection ratio of the FP filter and that the average improvement in modulation depth is 13.7 dB under specified conditions. PMID:15929296

  10. GPR signal enhancement using band-pass and K-L filtering: a case study for the evaluation of grout in a shielded tunnel

    NASA Astrophysics Data System (ADS)

    Xie, Xiongyao; Zeng, Chenchao; Wang, Zhigao

    2013-06-01

    The rapidness, non-destructiveness and high precision of ground penetrating radar (GPR) technology has enabled it to be widely and increasingly used in tunnel detection. However, data acquisition was usually restricted by physical and many other limitations. In order to improve the signal-to-noise ratio, band-pass and Karhunen-Loève (K-L) filtering are recommended. An evaluation of Yingbin No. 3 Road Tunnel is presented to illustrate the effectiveness of GPR in the inspection of the thickness of the grouting layer behind the segment and the function of the two methods mentioned above. The advantages and limitations of these two processing methods are discussed in this paper and suggestions are provided.

  11. Exploring mechanisms of spontaneous functional connectivity in MEG: how delayed network interactions lead to structured amplitude envelopes of band-pass filtered oscillations.

    PubMed

    Cabral, Joana; Luckhoo, Henry; Woolrich, Mark; Joensson, Morten; Mohseni, Hamid; Baker, Adam; Kringelbach, Morten L; Deco, Gustavo

    2014-04-15

    Spontaneous (or resting-state) brain activity has attracted a growing body of neuroimaging research over the last decades. Whole-brain network models have proved helpful to investigate the source of slow (<0.1 Hz) correlated hemodynamic fluctuations revealed in fMRI during rest. However, the mechanisms mediating resting-state long-distance correlations and the relationship with the faster neural activity remain unclear. Novel insights coming from MEG studies have shown that the amplitude envelopes of alpha- and beta-frequency oscillations (~8-30 Hz) display similar correlation patterns as the fMRI signals. In this work, we combine experimental and theoretical work to investigate the mechanisms of spontaneous MEG functional connectivity. Using a simple model of coupled oscillators adapted to incorporate realistic whole-brain connectivity and conduction delays, we explore how slow and structured amplitude envelopes of band-pass filtered signals - fairly reproducing MEG data collected from 10 healthy subjects at rest - are generated spontaneously in the space-time structure of the brain network. Our simulation results show that the large-scale neuroanatomical connectivity provides an optimal network structure to support a regime with metastable synchronization. In this regime, different subsystems may temporarily synchronize at reduced collective frequencies (falling in the 8-30 Hz range due to the delays) while the global system never fully synchronizes. This mechanism modulates the frequency of the oscillators on a slow time-scale (<0.1 Hz) leading to structured amplitude fluctuations of band-pass filtered signals. Taken overall, our results reveal that the structured amplitude envelope fluctuations observed in resting-state MEG data may originate from spontaneous synchronization mechanisms naturally occurring in the space-time structure of the brain. PMID:24321555

  12. Fibre coupled micro-light emitting diode array light source with integrated band-pass filter for fluorescence detection in miniaturised analytical systems.

    PubMed

    Vaculovičová, Markéta; Akther, Mahbub; Maaskant, Pleun; Brabazon, Dermot; Macka, Mirek

    2015-04-29

    In this work, a new type of miniaturized fibre-coupled solid-state light source is demonstrated as an excitation source for fluorescence detection in capillary electrophoresis. It is based on a parabolically shaped micro-light emitting diode (μ-LED) array with a custom band-pass optical interference filter (IF) deposited at the back of the LED substrate. The GaN μ-LED array consisted of 270 individual μ-LED elements with a peak emission at 470 nm, each about 14 μm in diameter and operated as a single unit. Light was extracted through the transparent substrate material, and coupled to an optical fibre (OF, 400 μm in diameter, numerical aperture NA=0.37), to form an integrated μ-LED-IF-OF light source component. This packaged μ-LED-IF-OF light source emitted approximately 225 μW of optical power at a bias current of 20 mA. The bandpass IF filter was designed to reduce undesirable LED light emissions in the wavelength range above 490 nm. Devices with and without IF were compared in terms of the optical power output, spectral characteristics as well as LOD values. While the IF consisted of only 7.5 pairs (15 layers) of SiO2/HfO2 layers, it resulted in an improvement of the baseline noise as well as the detection limit measured using fluorescein as test analyte, both by approximately one order of magnitude, with a LOD of 1×10(-8) mol L(-1) obtained under optimised conditions. The μ-LED-IF-OF light source was then demonstrated for use in capillary electrophoresis with fluorimetric detection. The limits of detection obtained by this device were compared to those obtained with a commercial fibre coupled LED device. PMID:25847165

  13. Ultra-Compact Broadband High-Spurious Suppression Bandpass Filter Using Double Split-end Stepped Impedance Resonators

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop; Wollack, Ed; Papapolymerou, John; Laskar, Joy

    2005-01-01

    We propose an ultra compact single-layer spurious suppression band pass filter design which has the following benefit: 1) Effective coupling area can be increased with no fabrication limitation and no effect on the spurious response; 2) Two fundamental poles are introduced to suppress spurs; 3) Filter can be designed with up to 30% bandwidth; 4) The Filter length is reduced by at least 100% when compared to the conventional filter; 5) Spurious modes are suppressed up to at the seven times the fundamental frequency; and 6) It uses only one layer of metallization which minimize the fabrication cost.

  14. A new facility for manufacturing and testing very large narrow bandpass filters and other high performance optical coatings

    NASA Astrophysics Data System (ADS)

    Mooney, Thomas; Pawlewicz, Walter; Merrill, Michael; Leclerc, David; Hurd, Kerry

    2014-07-01

    Optical coatings are key elements of any optical system. They can reduce surface reflection loss, isolate spectral bands, re-direct the light path and split light beams by wavelength. For decades, astronomers have made use of these special characteristics embodied in Anti-Reflection (AR) coatings, Band Pass (BP) filters, mirrors and Dichroic Beamsplitters (DBS). In the last several years, a need has arisen for much larger high performance filters and coatings. This is being driven by the ever increasing size of new and planned telescopes with their correspondingly larger focal planes. Typical Broadband filters require modest wavelength uniformity and can be produced in legacy (existing) coating chambers, even in fairly large formats. However, some new instruments require narrow BP (NBP) filters of 60 cm or greater diameter in order to perform efficiently. Some planned systems will even require filters in the 75 cm diameter range. The implications for coating such large, very expensive optics are that the equipment must not only accommodate a large optic, but the process must achieve excellent uniformity over broad areas. It must also exhibit excellent performance, reproducibility and reliability in depositions consisting of well over one hundred layers and many hours duration. And finally, the spectral performance must be verifiable, not through an indirect method, but directly of the science optic itself. To address these challenges, Materion designed, built, tested and put into production a purposebuilt laboratory. This paper will describe in detail the elements of the lab creation and initial achievements.

  15. Compact ultra wide band microstrip bandpass filter based on multiple-mode resonator and modified complementary split ring resonator.

    PubMed

    Marcotegui, J Antonio; Illescas, Jesús Miguel; Estevez, Aritz; Falcone, Francisco

    2013-01-01

    A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring Resonator (MCSRR)-a concept proposed here for the first time-are adjusted to obtain the desired response with broadband, sharp rejection, low insertion loss, and low return loss. Full wave simulation results as well as measurement results from fabricated prototypes are presented, showing good agreement. The proposed technique offers a new alternative to implement low-cost high-performance filter devices, applicable to a wide range of communication systems. PMID:24319366

  16. Compact Ultra Wide Band Microstrip Bandpass Filter Based on Multiple-Mode Resonator and Modified Complementary Split Ring Resonator

    PubMed Central

    Marcotegui, J. Antonio; Illescas, Jesús Miguel; Estevez, Aritz

    2013-01-01

    A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring Resonator (MCSRR)—a concept proposed here for the first time—are adjusted to obtain the desired response with broadband, sharp rejection, low insertion loss, and low return loss. Full wave simulation results as well as measurement results from fabricated prototypes are presented, showing good agreement. The proposed technique offers a new alternative to implement low-cost high-performance filter devices, applicable to a wide range of communication systems. PMID:24319366

  17. Linear absorption coefficient of beryllium in the 50-300-A wavelength range. [bandpass filter materials for ultraviolet astronomy instrumentation

    NASA Technical Reports Server (NTRS)

    Barstow, M. A.; Lewis, M.; Petre, R.

    1983-01-01

    Transmittances of thin-film filters fabricated for an extreme-UV astronomy sounding-rocket experiment yield values for the linear absorption coefficient of beryllium in the 50-300-A wavelength range, in which previous measurements are sparse. The inferred values are consistent with the lowest data previously published and may have important consequences for extreme-UV astronomers.

  18. Silicon band-rejection and band-pass filter based on asymmetric Bragg sidewall gratings in a multimode waveguide.

    PubMed

    Qiu, Huiye; Jiang, Jianfei; Yu, Ping; Dai, Tingge; Yang, Jianyi; Yu, Hui; Jiang, Xiaoqing

    2016-06-01

    A silicon photonic wire filter based on an asymmetric sidewall Bragg grating in a multimode silicon-on-insulator strip waveguide is demonstrated. The operating principle is based on the contra-directional coupling between the transverse electric fundamental (TE0) and first-order (TE1) modes, which is enabled by the asymmetric spatially periodic refractive-index perturbations. An asymmetric Y-junction is cascaded at the input port of the filter so as to drop the Bragg reflection. Compared with conventional Bragg grating-based filters, this device eliminates the back reflection at the input port and the 6 dB inherent insertion loss at the drop port; moreover, a narrow 3 dB bandwidth can be obtained with a large critical dimension as a result of the weak coupling strength between the TE0 and TE1 modes inside the multimode waveguide. Experimental results show that a bandwidth of ∼2.8  nm is achieved by a large corrugation width of 150 nm. The insertion loss at the drop port is -2.1  dB, and the extinction ratio is -33  dB at the through port. PMID:27244386

  19. Correlation of microwave nonlinearity and magnetic pinning in high-temperature superconductor thin film band-pass filters

    NASA Astrophysics Data System (ADS)

    Zhao, Hua; Wang, Xiang; Wu, Judy Z.

    2008-08-01

    Third-order intermodulation has been studied in two-pole X-band microstrip filters made of three high-temperature superconductors (HTS), including HgBa2CaCu2O6+δ (Hg-1212), Tl2Ba2CaCu2Oy (Tl-2212) and YBa2Cu3O7-δ (YBCO) at >=77 K. In addition, the dc critical current density Jc was investigated in these three types of HTS films in the same temperature range. Interestingly, the dc Jc and the rf critical current density JIP3 derived from the third-order intercept (IP3) have a similar dependence on the reduced temperature, suggesting that the magnetic vortex depinning in HTS materials dominates the microwave nonlinearity at elevated temperatures. This observation agrees with the recent theoretical discussion on the origin of the microwave nonlinearity. Disagreement between Jc and JIP3, however, has been observed in the trilayer YBCO/CeO2/YBCO filters. Although magnetic flux pinning and hence Jc were improved by the insertion of a 20 nm thin CeO2 layer, the reduced JIP3 is attributed to the high power loss from the extra interfaces between YBCO and CeO2.

  20. Intensive Plasmonic Flash Light Sintering of Copper Nanoinks Using a Band-Pass Light Filter for Highly Electrically Conductive Electrodes in Printed Electronics.

    PubMed

    Hwang, Yeon-Taek; Chung, Wan-Ho; Jang, Yong-Rae; Kim, Hak-Sung

    2016-04-01

    In this work, an intensive plasmonic flash light sintering technique was developed by using a band-pass light filter matching the plasmonic wavelength of the copper nanoparticles. The sintering characteristics, such as resistivity and microstructure, of the copper nanoink films were studied as a function of the range of the wavelength employed in the flash white light sintering. The flash white light irradiation conditions (e.g., wavelength range, irradiation energy, pulse number, on-time, and off-time) were optimized to obtain a high conductivity of the copper nanoink films without causing damage to the polyimide substrate. The wavelength range corresponding to the plasmonic wavelength of the copper nanoparticles could efficiently sinter the copper nanoink and enhance its conductivity. Ultimately, the sintered copper nanoink films under optimal light sintering conditions showed the lowest resistivity (6.97 μΩ·cm), which was only 4.1 times higher than that of bulk copper films (1.68 μΩ·cm). PMID:26975337

  1. Flat-top bandpass microwave photonic filter with tunable bandwidth and center frequency based on a Fabry-Pérot semiconductor optical amplifier.

    PubMed

    Jiang, Fan; Yu, Yuan; Cao, Tong; Tang, Haitao; Dong, Jianji; Zhang, Xinliang

    2016-07-15

    We propose a flat-top bandpass microwave photonic filter (MPF) with flexible tunability of the bandwidth and center frequency based on optical nonlinearities in a Fabry-Pérot semiconductor optical amplifier (FP-SOA). Phase-inverted modulation induced by cross-gain modulation (XGM) and optical spectral broadening induced by self-phase modulation (SPM) are exploited to achieve flat-top and bandwidth tuning, respectively. Wideband and continuous tuning of the center frequency is achieved by altering the bias current of the FP-SOA. Experimental results demonstrate a flat-top single-passband MPF with its center frequency tunable from 6.0 to 18.3 GHz by adjusting the bias current from 54.05 to 107.85 mA. The 3-dB bandwidth of the passband when centered at 10.0 GHz is shown to be variable from 680 to 1.43 GHz, by increasing the injected optical power from -1 to +5  dBm. During the bandwidth tuning, the amplitude ripple within the passband is maintained at less than ±0.5  dB. Excellent main to secondary sidelobe ratio exceeding 45 dB is achieved when the MPF is centered at 18.3 GHz. PMID:27420520

  2. Effect of RF Filtering on the Performance of Uncoded PCM/PM Telemetry Channels

    NASA Technical Reports Server (NTRS)

    Koerner, M. A.

    1984-01-01

    A method for calculating the increase in received telemetry signal power required to compensate for the use of a radio frequency interference (RFI) filter in front of the DSN receiving system low-noise amplifier is described. The telemetry system for which the degradation is calculated is an uncoded PCM/PM system in which the NRZ data directly modulates the carrier at a modulation level which leaves a discrete carrier. A phase-locked loop in the RF receiver tracks the discrete carrier and coherently demodulates the PCM data. The RFI filter may be a series of Butterworth, Tchebychev, or Bessel low-pass, high-pass, band-pass, or band-reject filters, each with arbitrary bandwidth, number of poles, and, for band-pass or band-reject filters, resonant frequency. The only restriction is that the RFI filter must have only simple poles. Numerical results are presented for the RFI filters the DSN plans to place in front of the S-band FET, S-band maser, and X-band maser low noise amplifiers. The main conclusion is that the filters will produce negligible degradation at data rates below 4 Mbps.

  3. Study of a mode-locked erbium-doped frequency-shifted-feedback fiber laser incorporating a broad bandpass filter: Experimental results

    NASA Astrophysics Data System (ADS)

    Vazquez-Zuniga, Luis Alonso; Jeong, Yoonchan

    2013-10-01

    We present rigorous experimental studies on the spectral and temporal behaviors of an erbium-doped frequency-shifted-feedback fiber laser (FSFL), with respect to various parameters of the laser cavity, including the direction of the frequency-shift mechanism, the quantity of frequency-shift, and the output coupling ratio (OCR) of the cavity. We show that if the filter bandwidth is much broader than the laser linewidth, the laser spectrum tends to split and form a secondary spectral band (SSB) on the shorter or longer wavelength side of the primary spectrum, depending on whether the direction of the frequency-shift mechanism is upward or downward, respectively. We found that the SSB forms a parasitic pulse with much lower peak power traveling on the leading or trailing edge of the primary pulse, which leads to a significant asymmetry in the whole pulse formation in the time domain.

  4. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  5. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  6. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  7. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  8. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  9. Filter Design and Performance Evaluation for Fingerprint Image Segmentation

    PubMed Central

    Thai, Duy Hoang; Huckemann, Stephan; Gottschlich, Carsten

    2016-01-01

    Fingerprint recognition plays an important role in many commercial applications and is used by millions of people every day, e.g. for unlocking mobile phones. Fingerprint image segmentation is typically the first processing step of most fingerprint algorithms and it divides an image into foreground, the region of interest, and background. Two types of error can occur during this step which both have a negative impact on the recognition performance: ‘true’ foreground can be labeled as background and features like minutiae can be lost, or conversely ‘true’ background can be misclassified as foreground and spurious features can be introduced. The contribution of this paper is threefold: firstly, we propose a novel factorized directional bandpass (FDB) segmentation method for texture extraction based on the directional Hilbert transform of a Butterworth bandpass (DHBB) filter interwoven with soft-thresholding. Secondly, we provide a manually marked ground truth segmentation for 10560 images as an evaluation benchmark. Thirdly, we conduct a systematic performance comparison between the FDB method and four of the most often cited fingerprint segmentation algorithms showing that the FDB segmentation method clearly outperforms these four widely used methods. The benchmark and the implementation of the FDB method are made publicly available. PMID:27171150

  10. Filter Design and Performance Evaluation for Fingerprint Image Segmentation.

    PubMed

    Thai, Duy Hoang; Huckemann, Stephan; Gottschlich, Carsten

    2016-01-01

    Fingerprint recognition plays an important role in many commercial applications and is used by millions of people every day, e.g. for unlocking mobile phones. Fingerprint image segmentation is typically the first processing step of most fingerprint algorithms and it divides an image into foreground, the region of interest, and background. Two types of error can occur during this step which both have a negative impact on the recognition performance: 'true' foreground can be labeled as background and features like minutiae can be lost, or conversely 'true' background can be misclassified as foreground and spurious features can be introduced. The contribution of this paper is threefold: firstly, we propose a novel factorized directional bandpass (FDB) segmentation method for texture extraction based on the directional Hilbert transform of a Butterworth bandpass (DHBB) filter interwoven with soft-thresholding. Secondly, we provide a manually marked ground truth segmentation for 10560 images as an evaluation benchmark. Thirdly, we conduct a systematic performance comparison between the FDB method and four of the most often cited fingerprint segmentation algorithms showing that the FDB segmentation method clearly outperforms these four widely used methods. The benchmark and the implementation of the FDB method are made publicly available. PMID:27171150

  11. Design and experimental characterization of a bandpass sampling receiver

    NASA Astrophysics Data System (ADS)

    Singh, Avantika; Kumar, Devika S.; Venkateswaran, Gomathy; Manjukrishna, S.; Singh, Amrendra Kumar; Kurup, Dhanesh G.

    2016-03-01

    In this paper, we present a robust and efficient approach for deigning reconfigurable Radio receivers based on Bandpass sampling. The direct sampled RF frontend is followed by signal processing blocks implemented on an FPGA and consists of a PLL based on second order Costas technique and a Kaiser windowing based lowpass filtering. The proposed method can be used for implementing a cost effective multi-channel receiver for data, audio, video etc. over various channels.

  12. Bandpass x-ray diode and x-ray multiplier detector

    DOEpatents

    Wang, C.L.

    1982-09-27

    An absorption-edge of an x-ray absorption filter and a quantum jump of a photocathode determine the bandpass characteristics of an x-ray diode detector. An anode, which collects the photoelectrons emitted by the photocathode, has enhanced amplification provided by photoelectron-multiplying means which include dynodes or a microchannel-plate electron-multiplier. Suppression of undesired high frequency response for a bandpass x-ray diode is provided by subtracting a signal representative of energies above the passband from a signal representative of the overall response of the bandpass diode.

  13. Soliton transmission control by super-Gaussian filters

    NASA Astrophysics Data System (ADS)

    Peral, E.; Capmany, J.; Marti, J.

    1996-12-01

    Bandwidth-limited filtering has been proven to overcome certain limitations in soliton transmission systems. We propose super-Gaussian filters instead of Butterworth filter response obtained with conventionally used Fabry-Perot etalons as a method to improve soliton stability and reduce dispersion degradation and theoretically demonstrate their practical implementation in the form of holographic fiber gratings.

  14. Band-pass processing in a GPCR signaling pathway selects for NFAT transcription factor activation.

    PubMed

    Sumit, M; Neubig, R R; Takayama, S; Linderman, J J

    2015-11-01

    Many biological processes are rhythmic and proper timing is increasingly appreciated as being critical for development and maintenance of physiological functions. To understand how temporal modulation of an input signal influences downstream responses, we employ microfluidic pulsatile stimulation of a G-protein coupled receptor, the muscarinic M3 receptor, in single cells with simultaneous real-time imaging of both intracellular calcium and NFAT nuclear localization. Interestingly, we find that reduced stimulation with pulses of ligand can give more efficient transcription factor activation, if stimuli are timed appropriately. Our experiments and computational analyses show that M3 receptor-induced calcium oscillations form a low pass filter while calcium-induced NFAT translocation forms a high pass filter. The combination acts as a band-pass filter optimized for intermediate frequencies of stimulation. We demonstrate that receptor desensitization and NFAT translocation rates determine critical features of the band-pass filter and that the band-pass may be shifted for different receptors or NFAT dynamics. As an example, we show that the two NFAT isoforms (NFAT4 and NFAT1) have shifted band-pass windows for the same receptor. While we focus specifically on the M3 muscarinic receptor and NFAT translocation, band-pass processing is expected to be a general theme that applies to multiple signaling pathways. PMID:26374065

  15. Low-Noise Band-Pass Amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L.

    1982-01-01

    Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.

  16. Properties of multilayer filters

    NASA Technical Reports Server (NTRS)

    Baumeister, P. W.

    1973-01-01

    New methods were investigated of using optical interference coatings to produce bandpass filters for the spectral region 110 nm to 200 nm. The types of filter are: triple cavity metal dielectric filters; all dielectric reflection filters; and all dielectric Fabry Perot type filters. The latter two types use thorium fluoride and either cryolite films or magnesium fluoride films in the stacks. The optical properties of the thorium fluoride were also measured.

  17. Nonuniformly-spaced photonic microwave delayline filter.

    PubMed

    Dai, Yitang; Yao, Jianping

    2008-03-31

    A new technique to implement a photonic microwave delay-line filter based on nonuniform tap spacing with arbitrary bandpass response is proposed and experimentally demonstrated. Being different from a regular photonic microwave delay-line filter where the taps are uniformly spaced, the proposed filter in this paper has nonuniformly-spaced taps. The key feature of this technique is that a photonics microwave delay-line filter with arbitrary bandpass response can be realized with only positive taps via nonuniform tap spacing. The use of the proposed technique to implement a flat-top bandpass filter is experimentally demonstrated. PMID:18542568

  18. Microwave photonic bandstop filter with wide tunability and adjustable bandwidth.

    PubMed

    Li, Wei; Yang, Chengwu; Wang, Ling; Yuan, Zhilin; Liu, Jianguo; Li, Ming; Zhu, Ninghua

    2015-12-28

    A microwave photonic bandstop filter is proposed and experimentally demonstrated in this work. The filter exhibits promising performance combination of reconfigurability, frequency tunability, and bandwidth adjustment. The phase modulation on two orthogonal polarization states produces a bandpass and a lowpass MPF, respectively. The key concept of destructive interference between the bandpass and lowpass MPF enables the reconfiguration of MPF from bandpass to bandstop. By adjusting the wavelength of two orthogonally polarized optical carriers and the bandwidth of an optical bandpass filter, the bandstop filter is tunable in terms of center frequency and bandwidth. PMID:26832021

  19. Photonic crystal fiber π-phase-shifted long-period gratings with wide bandpass and temperature insensitivity

    NASA Astrophysics Data System (ADS)

    Zheng, Shijie; Zhu, Yinian

    2015-11-01

    In order to solve for the mode intensity distributions in a photonic crystal fiber (PCF) cross section and the propagation constant for the design of fiber bandpass filters, we numerically analyze the modal distributions of the fundamental core mode and different cladding modes. Based on the simulation results, we also experimentally demonstrate a simple fabrication of bandpass filters inscribed on the PCF by inserting a π-phase shift in a 12-period long-period grating (LPG). Two rejection bands with greater than 18 dB isolation and an ultra-wide band of 85.3 nm are achieved. The phase-shifted PCF-LPGs are fabricated using a CO2 laser with point-by-point focused pulses. The proposed fiber bandpass filter is compact and is not influenced by temperature effects.

  20. DFB fiber laser hydrophone with band-pass response.

    PubMed

    Zhang, Faxiang; Zhang, Wentao; Li, Fang; Liu, Yuliang

    2011-11-15

    A distributed-feedback fiber laser hydrophone with band-pass response is presented. The design of the hydrophone aims to equalize static pressure and eliminate signal aliasing of high-frequency acoustic components. Theoretical analysis is presented based on electro-acoustic theory. The experimental results agree well with the theory. The measured underwater responses show that the hydrophone has a pressure sensitivity of -170 dB re:pm/μPa over a bandwidth between 100 Hz and 500 Hz. A sensitivity reduction exceeding -35 dB is observed at 2500 Hz. The tested static pressure sensitivity of the hydrophone is -226 dB. The proposed fiber laser hydrophone of this kind is expected to have important application in deep water fiber-optic sonar systems with anti-aliasing, and the understanding gained through this work can be extended to a guide of hydrophone design for required filtering bandwidth. PMID:22089550

  1. FORTRAN IV Digital Filter Design Programs. Digital Systems Education Project.

    ERIC Educational Resources Information Center

    Reuss, E.; And Others

    The goals of the Digital Systems Education Project (DISE) include the development and distribution of educational/instructional materials in the digital systems area. Toward that end, this document contains three reports: (1) A FORTRAN IV Design Program for Low-Pass Butterworth and Chebychev Digital Filters; (2) A FORTRAN IV Design Program for…

  2. Tunable Filter Made From Three Coupled WGM Resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Iltchenko, Vladimir; Maleki, Lute; Matsko, Andrey

    2006-01-01

    A tunable third-order band-pass optical filter has been constructed as an assembly of three coupled, tunable, whispering-gallery-mode resonators similar to the one described in Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter (NPO-30896), NASA Tech Briefs, Vol. 28, No. 4 (April 2004), page 5a. This filter offers a combination of four characteristics that are desirable for potential applications in photonics: (1) wide real-time tunability accompanied by a high-order filter function, (2) narrowness of the passband, (3) relatively low loss between input and output coupling optical fibers, and (4) a sparse spectrum. In contrast, prior tunable band-pass optical filters have exhibited, at most, two of these four characteristics. As described in several prior NASA Tech Briefs articles, a whispering-gallery-mode (WGM) resonator is a spheroidal, disklike, or toroidal body made of a highly transparent material. It is so named because it is designed to exploit whispering-gallery electromagnetic modes, which are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. Figure 1 depicts the optical layout of the present filter comprising an assembly of three coupled, tunable WGM resonators. Each WGM resonator is made from a disk of Z-cut LiNbO3 of 3.3-mm diameter and 50-m thickness. The perimeter of the disk is polished and rounded to a radius of curvature of 40 microns. The free spectral range of each WGM resonator is about 13.3 GHz. Gold coats on the flat faces of the disk serve as electrodes for exploiting the electro-optical effect in LiNbO3 for tuning. There is no metal coat on the rounded perimeter region, where the whispering-gallery modes propagate. Light is coupled from an input optical fiber into the whispering-gallery-modes of the first WGM resonator by means of a diamond prism. Another diamond prism is used to couple light from the whispering

  3. Sensitivity of bandpass filters using recirculating delay-line structures

    NASA Astrophysics Data System (ADS)

    Heyde, Eric C.

    1996-12-01

    Recirculating delay lines have value notably as sensors and optical signal processors. Most useful applications depend on a high-finesse response from a network. A proof that, with given response parameters, more complex systems can produce behavior that is more stable to the effects of nonidealities than a single recirculating loop is presented.

  4. Tunable microwave photonic notch filter based on sliced broadband optical source.

    PubMed

    Yu, Yang; Li, Shangyuan; Zheng, Xiaoping; Zhang, Hanyi; Zhou, Bingkun

    2015-09-21

    A microwave photonic filter is demonstrated with both tunable center frequency and bandwidth. This filter is switchable from all-pass, bandpass to notch filter, and the notch filter is a result of the subtraction of a bandpass filter from an all-pass filter based on a balanced photodetector. The all-pass filter is achieved based on a single wavelength radio over fiber link, and the bandpass one is acquired by using the spectrum-sliced broadband optical source. Theoretical analysis and experimental results show that both the center frequency and the bandwidth of the notch filter can be widely tuned. PMID:26406636

  5. Comparison of deformation at ends of the results obtained by some commonly used filters

    NASA Astrophysics Data System (ADS)

    Liao, Dechun; Liao, Xinhao

    By using some commonly used filters, such as MULTI-STAGE, ELLIPSE, CHEBYSHEV, and BUTTERWORTH, seasonal, interannual, and decadal components are separated from a synthetic LOD series which was composed of 11 periodic terms extracted from a real LOD series during 1962 - 1998. And then comparisons of the filtered results with the original components have been made to investigate the deformations induced by the different filters at the two ends of the data series. Some results are shown. It is clear by the comparison that the MULTI-STAGE filter has least deformation rate at the two ends of series either it is used for high or low pass filtering, the BUTTERWORTH (for high pass filtering) and CHEBYSHEV (for low pass filtering) have less deformation among the others. For the band pass filtering, however, the CHEBYSHEV filter has least deformation. After adding some extended data obtained by fitting the original data series as a linear statistical model, comparison of the filtered results show that the BUTTERWORTH and ELLIPSE filters have least deformations for band pass filtering. The ends deformation induced by filtering will be smaller for any filters after adding of some statistically extended data to the original series.

  6. A class of orthogonal nonrecursive binomial filters.

    NASA Technical Reports Server (NTRS)

    Haddad, R. A.

    1971-01-01

    The time- and frequency-domain properties of the orthogonal binomial sequences are presented. It is shown that these sequences, or digital filters based on them, can be generated using adders and delay elements only. The frequency-domain behavior of these nonrecursive binomial filters suggests a number of applications as low-pass Gaussian filters or as inexpensive bandpass filters.

  7. Optimum filters for narrow-band frequency modulation.

    NASA Technical Reports Server (NTRS)

    Shelton, R. D.

    1972-01-01

    The results of a computer search for the optimum type of bandpass filter for low-index angle-modulated signals are reported. The bandpass filters are discussed in terms of their low-pass prototypes. Only filter functions with constant numerators are considered. The pole locations for the optimum filters of several cases are shown in a table. The results are fairly independent of modulation index and bandwidth.

  8. Reliability of Three-Dimensional Linear Kinematics and Kinetics of Swimming Derived from Digitized Video at 25 and 50 Hz with 10 and 5 Frame Extensions to the 4(th) Order Butterworth Smoothing Window.

    PubMed

    Sanders, Ross H; Gonjo, Tomohiro; McCabe, Carla B

    2015-06-01

    The purpose of this study was to explore the reliability of estimating three-dimensional (3D) linear kinematics and kinetics of a swimmer derived from digitized video and to assess the effect of framing rate and smoothing window size. A stroke cycle of two high-level front crawl swimmers and one high level backstroke swimmer was recorded by four underwater and two above water video cameras. One of the front crawl swimmers was recorded and digitized at 50 Hz with a window for smoothing by 4(th) order Butterworth digital filter extending 10 frames beyond the start and finish of the stroke cycle, while the other front crawl and backstroke swimmer were recorded and digitized at 25 Hz with the window extending five frames beyond the start and finish of the stroke cycle. Each camera view of the stroke cycle was digitized five times yielding five independent 3D data sets from which whole body centre of mass (CM) component velocities and accelerations were derived together with wrist and ankle linear velocities. Coefficients of reliability ranging from r = 0.942 to r = 0.999 indicated that both methods are sufficiently reliable to identify real differences in net force production during the pulls of the right and left hands. Reliability of digitizing was better for front crawl when digitizing at 50Hz with 10 frames extension than at 25 Hz with 5 frames extension (p < 0.01) and better for backstroke than front crawl (p < 0.01). However, despite the extension and reflection of data, errors were larger in the first 15% of the stroke cycle than the period between 15 and 85% of the stroke cycle for CM velocity and acceleration and for foot speed (p < 0.01). Key pointsAn inverse dynamics based on 3D position data digitized from multiple camera views above and below the water surface is sufficiently reliable to yield insights regarding force production in swimming additional to those of other approaches.The ability to link the force profiles to swimming actions and technique is

  9. Temperature Tunable Air-Gap Etalon Filter

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Stephen, Mark A.; Lunt, David L.

    1998-01-01

    We report on experimental measurements of a temperature tuned air-gap etalon filter. The filter exhibits temperature dependent wavelength tuning of 54 pm/C. It has a nominal center wavelength of 532 nm. The etalon filter has a 27 pm optical bandpass and 600 pm free spectral range (finesse approximately 22). The experimental results are in close agreement with etalon theory.

  10. Mechanism for bandpass frequency characteristic in distortion product otoacoustic emission generation.

    PubMed

    Fahey, P F; Stagner, B B; Martin, G K

    2006-02-01

    It is commonly observed that the levels of the 2f1-f2 and the other mf1-nf2 (m = n + 1 = integer) distortion product otoacoustic emissions (DPOAEs) initially increase in level for fixed f2 as fl -->f2, starting at f1 bandpass shape. It has been hypothesized that this effect is due to (1) a second filter, (2) suppression of distortion generation by the primary tones, (3) reemission of distortion products from the distortion product place (on the basilar membrane), (4) the presence of an even order nonlinearity, and (5) cancellation of the DPOAE due to the vector addition of multiple sources of distortion product. In this study distortion products were produced with f1 sweep conditions where there would be minimal vector cancellation of multiple DPOAE sources. It was observed that under this condition, there is no or minimal bandpass shape of the DPOAE generation curve. Therefore, the data support the hypothesis that the bandpass shape obtained with traditional f1 sweeps is due to vector cancellation from multiple sources. PMID:16521760

  11. Optimizing the performance of bandpass photon detectors for inverse photoemission: Transmission of alkaline earth fluoride window crystals

    SciTech Connect

    Thiede, Christian Schmidt, Anke B.; Donath, Markus

    2015-08-15

    Bandpass photon detectors are widely used in inverse photoemission in the isochromat mode at energies in the vacuum-ultraviolet spectral range. The energy bandpass of gas-filled counters is usually formed by the ionization threshold of the counting gas as high-pass filter and the transmission cutoff of an alkaline earth fluoride window as low-pass filter. The transmission characteristics of the window have, therefore, a crucial impact on the detector performance. We present transmission measurements in the vacuum-ultraviolet spectral range for alkaline earth fluoride window crystals in the vicinity of the transmission cutoff as a function of crystal purity, surface finish, surface contamination, temperature, and thickness. Our findings reveal that the transmission characteristics of the window crystal and, thus, the detector performance depend critically on these window parameters.

  12. Research on spectroscopic imaging. Volume 1: Technical discussion. [birefringent filters

    NASA Technical Reports Server (NTRS)

    Title, A.; Rosenberg, W.

    1979-01-01

    The principals of operation and the capabilities of birefringent filters systems are examined. Topics covered include: Lyot, Solc, and partial polarizer filters; transmission profile management; tuning birefringent filters; field of view; bandpass control; engineering considerations; and recommendations. Improvements for field of view effects, and the development of birefringent filters for spaceflight are discussed in appendices.

  13. Reconfigurable microwave photonic filter based on polarization modulation

    NASA Astrophysics Data System (ADS)

    Xu, Enming; Pan, Shilong; Li, Peili

    2016-03-01

    A reconfigurable microwave photonic filter based on a polarization modulator (PolM) is proposed and experimentally demonstrated. The PolM together with a polarization controller (PC) and a polarization beam splitter (PBS) implements two complementary intensity modulations in two separated branches. Then, optical components are inserted in the two branches to realize a bandpass filter and an allpass filter, respectively. When the two branches are combined by a second PBS, a filter with a frequency response that equals the subtraction of the frequency responses of the allpass filter and bandpass filter is achieved. By adjusting the PCs placed before the second PBS, a notch filter with a tunable notch depth or a bandpass filter can be achieved.

  14. Active imaging system with Faraday filter

    DOEpatents

    Snyder, J.J.

    1993-04-13

    An active imaging system has a low to medium powered laser transmitter and receiver wherein the receiver includes a Faraday filter with an ultranarrow optical bandpass and a bare (nonintensified) CCD camera. The laser is locked in the vicinity of the passband of the Faraday filter. The system has high sensitivity to the laser illumination while eliminating solar background.

  15. Active imaging system with Faraday filter

    DOEpatents

    Snyder, James J.

    1993-01-01

    An active imaging system has a low to medium powered laser transmitter and receiver wherein the receiver includes a Faraday filter with an ultranarrow optical bandpass and a bare (nonintensified) CCD camera. The laser is locked in the vicinity of the passband of the Faraday filter. The system has high sensitivity to the laser illumination while eliminating solar background.

  16. Design and application of finite impulse response digital filters.

    PubMed

    Miller, T R; Sampathkumaran, K S

    1982-01-01

    The finite impulse response (FIR) digital filter is a spatial domain filter with a frequency domain representation. The theory of the FIR filter is presented and techniques are described for designing FIR filters with known frequency response characteristics. Rational design principles are emphasized based on characterization of the imaging system using the modulation transfer function and physical properties of the imaged objects. Bandpass, Wiener, and low-pass filters were designed and applied to 201Tl myocardial images. The bandpass filter eliminates low-frequency image components that represent background activity and high-frequency components due to noise. The Wiener, or minimum mean square error filter 'sharpens' the image while also reducing noise. The Wiener filter illustrates the power of the FIR technique to design filters with any desired frequency response. The low-pass filter, while of relative limited use, is presented to compare it with a popular elementary 'smoothing' filter. PMID:7060600

  17. Band-Pass Amplifier Without Discrete Reactance Elements

    NASA Technical Reports Server (NTRS)

    Kleinberg, L.

    1984-01-01

    Inherent or "natural" device capacitance exploited. Band-Pass Circuit has input impedance of equivalent circuit at frequencies much greater than operational-amplifier rolloff frequency. Apparent inductance and capacitance arise from combined effects of feedback and reactive component of amplifier gain in frequency range.

  18. Eulerian Time-Domain Filtering for Spatial LES

    NASA Technical Reports Server (NTRS)

    Pruett, C. David

    1997-01-01

    Eulerian time-domain filtering seems to be appropriate for LES (large eddy simulation) of flows whose large coherent structures convect approximately at a common characteristic velocity; e.g., mixing layers, jets, and wakes. For these flows, we develop an approach to LES based on an explicit second-order digital Butterworth filter, which is applied in,the time domain in an Eulerian context. The approach is validated through a priori and a posteriori analyses of the simulated flow of a heated, subsonic, axisymmetric jet.

  19. [Restoration filtering based on projection power spectrum for single-photon emission computed tomography].

    PubMed

    Kubo, N

    1995-04-01

    To improve the quality of single-photon emission computed tomographic (SPECT) images, a restoration filter has been developed. This filter was designed according to practical "least squares filter" theory. It is necessary to know the object power spectrum and the noise power spectrum. The power spectrum is estimated from the power spectrum of a projection, when the high-frequency power spectrum of a projection is adequately approximated as a polynomial exponential expression. A study of the restoration with the filter based on a projection power spectrum was conducted, and compared with that of the "Butterworth" filtering method (cut-off frequency of 0.15 cycles/pixel), and "Wiener" filtering (signal-to-noise power spectrum ratio was a constant). Normalized mean-squared errors (NMSE) of the phantom, two line sources located in a 99mTc filled cylinder, were used. NMSE of the "Butterworth" filter, "Wiener" filter, and filtering based on a power spectrum were 0.77, 0.83, and 0.76 respectively. Clinically, brain SPECT images utilizing this new restoration filter improved the contrast. Thus, this filter may be useful in diagnosis of SPECT images. PMID:7776546

  20. Second-order optical filter based on a mirrored gradient index lens.

    PubMed

    Liang, W; Savchenkov, A A; Matsko, A B; Ilchenko, V S; Seidel, D; Maleki, L

    2010-07-15

    We demonstrate a second-order bandpass filter using a single gradient index lens (GRIN) coated with mirrors. The filter becomes possible because of the residual and externally introduced small birefringence of the GRIN lens material. We show that the filter function can be trimmed by mechanical strain of the lens. Applications of the filter in microwave photonics are discussed. PMID:20634829

  1. Restoration of combined conjugate images in SPECT; Comparison of a new Weiner filter and the image-dependent Metz filter

    SciTech Connect

    Penny, B.C.; King, M.A.; Glick, S.J. . Dept. of Nuclear Medicine)

    1990-04-01

    This study applies two image-dependent restoration filters to projection image sets obtained with single photon emission computed tomography (SPECT). Wiener and Metz restoration of combined conjugate views are compared to: each other, Wiener restoration of individual projection images, and to one-dimensional (1D) Butterworth smoothing. The combined view restoration filters adapt to the average thickness of the object by estimating a modulation transfer function (MTF) for that thickness. Simulated Tc-99m liver-spleen studies with randomly placed cold spot tumors, a projector which accounts for the spatially variant blurring in SPECT, and a Poisson noise generator are used to compute simulated projection image sets.

  2. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification

    NASA Astrophysics Data System (ADS)

    Jena, D. P.; Panigrahi, S. N.

    2016-03-01

    Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.

  3. Magnetoencephalographic responses correspond to individual annoyance of bandpass noise

    NASA Astrophysics Data System (ADS)

    Soeta, Y.; Nakagawa, S.; Tonoike, M.; Ando, Y.

    2004-10-01

    The relation between human brain responses to an individual's annoyance of bandpass noise was investigated using magnetoencephalography (MEG) measurements and analysis by autocorrelation function (ACF) and cross-correlation function (CCF). Pure tone and bandpass noises with a centre frequency of 1000 Hz were used as source signals. The sound pressure level was constant at 74 dBA and the duration of the stimulus was 2.0 s. The scale values of annoyance for each subject were obtained by paired-comparison tests. In MEG measurements, the combination of a reference stimulus (pure tone) and test stimuli (bandpass noise) was alternately presented 30 times at a constant 2 s interstimulus interval. The results show that the effective duration of the ACF, τe, of MEG in the 8-13 Hz range, which represent repetitive features within the signal itself, became shorter during the presentation of an annoying stimulus. Also, the maximum value of the CCF, |φ(τ)|max, became smaller. The shorter τe and smaller |φ(τ)|max indicate that a wider area of the brain is unstable for longer with annoying auditory stimuli.

  4. Image quality, space-qualified UV interference filters

    NASA Technical Reports Server (NTRS)

    Mooney, Thomas A.

    1992-01-01

    The progress during the contract period is described. The project involved fabrication of image quality, space-qualified bandpass filters in the 200-350 nm spectral region. Ion-assisted deposition (IAD) was applied to produce stable, reasonably durable filter coatings on space compatible UV substrates. Thin film materials and UV transmitting substrates were tested for resistance to simulated space effects.

  5. Image pre-filtering for measurement error reduction in digital image correlation

    NASA Astrophysics Data System (ADS)

    Zhou, Yihao; Sun, Chen; Song, Yuntao; Chen, Jubing

    2015-02-01

    In digital image correlation, the sub-pixel intensity interpolation causes a systematic error in the measured displacements. The error increases toward high-frequency component of the speckle pattern. In practice, a captured image is usually corrupted by additive white noise. The noise introduces additional energy in the high frequencies and therefore raises the systematic error. Meanwhile, the noise also elevates the random error which increases with the noise power. In order to reduce the systematic error and the random error of the measurements, we apply a pre-filtering to the images prior to the correlation so that the high-frequency contents are suppressed. Two spatial-domain filters (binomial and Gaussian) and two frequency-domain filters (Butterworth and Wiener) are tested on speckle images undergoing both simulated and real-world translations. By evaluating the errors of the various combinations of speckle patterns, interpolators, noise levels, and filter configurations, we come to the following conclusions. All the four filters are able to reduce the systematic error. Meanwhile, the random error can also be reduced if the signal power is mainly distributed around DC. For high-frequency speckle patterns, the low-pass filters (binomial, Gaussian and Butterworth) slightly increase the random error and Butterworth filter produces the lowest random error among them. By using Wiener filter with over-estimated noise power, the random error can be reduced but the resultant systematic error is higher than that of low-pass filters. In general, Butterworth filter is recommended for error reduction due to its flexibility of passband selection and maximal preservation of the allowed frequencies. Binomial filter enables efficient implementation and thus becomes a good option if computational cost is a critical issue. While used together with pre-filtering, B-spline interpolator produces lower systematic error than bicubic interpolator and similar level of the random

  6. Metal mesh resonant filters for terahertz frequencies.

    PubMed

    Melo, Arline M; Kornberg, Mariano A; Kaufmann, Pierre; Piazzetta, Maria H; Bortolucci, Emílio C; Zakia, Maria B; Bauer, Otto H; Poglitsch, Albrecht; da Silva, Alexandre M P Alves

    2008-11-10

    The interest in terahertz photometric and imaging measurements has motivated the development of bandpass resonant filters to be coupled to multiple-pixel devices such as bolometer arrays. Resonant grids are relatively simple to fabricate, exhibiting high transmission at the central frequency, a narrow bandpass, and good rejection of the side frequencies of the spectrum. We have fabricated filters centered at different frequencies between 0.4 and 10 THz, using photolithography and electroforming techniques. Transmission measurements have shown center frequencies and bandwidths close to the design predictions. The performance of the filters was found not to be critically dependent on small physical deformations in the mesh, becoming more noticeable at higher frequencies (i.e., for smaller physical sizes). Wider bandwidths, needed to attain higher sensitivities in the continuum, were obtained by changing the design parameters for filters at 2 and 3 THz. PMID:19002231

  7. Bandpass sampling in heterodyne receivers for coherent optical access networks.

    PubMed

    Bakopoulos, Paraskevas; Dris, Stefanos; Schrenk, Bernhard; Lazarou, Ioannis; Avramopoulos, Hercules

    2012-12-31

    A novel digital receiver architecture for coherent heterodyne-detected optical signals is presented. It demonstrates the application of bandpass sampling in an optical communications context, to overcome the high sampling rate requirement of conventional receivers (more than twice the signal bandwidth). The concept is targeted for WDM coherent optical access networks, where applying heterodyne detection constitutes a promising approach to reducing optical hardware complexity. The validity of the concept is experimentally assessed in a 76 km WDM-PON scenario, where the developed DSP achieves a 50% ADC rate reduction with penalty-free operation. PMID:23388768

  8. Advanced astronomical interference filters from SCHOTT technology

    NASA Astrophysics Data System (ADS)

    Hull, Anthony B.; Reichel, Steffen; Brauneck, Ulf; Bourquin, Sebastien; Marin-Franch, Antoni

    2016-01-01

    Developing precision interference filters for astronomical radiometry often requires simultaneous solutions to very difficult requirements. SCHOTT's 80-year legacy methods with interference filters and 9,200-m2 facility dedicated to filters and optical fabrication bring multiple disciplines together to simultaneously solve requirements that include: narrow-band high-transmission, steep-edge bandpasses, extremely high out-of-band rejection across Si response, sizes accommodating large fields-of-view, precision mechanical filter assemblies and both spectral uniformity and excellent transmitted wavefront across the field. We discuss solutions as satisfied for Spain's state-of-the-art new fast LOCAL UNIVERSE 3° wide-field survey telescope.

  9. Spectral analysis and filtering techniques in digital spatial data processing

    USGS Publications Warehouse

    Pan, Jeng-Jong

    1989-01-01

    A filter toolbox has been developed at the EROS Data Center, US Geological Survey, for retrieving or removing specified frequency information from two-dimensional digital spatial data. This filter toolbox provides capabilities to compute the power spectrum of a given data and to design various filters in the frequency domain. Three types of filters are available in the toolbox: point filter, line filter, and area filter. Both the point and line filters employ Gaussian-type notch filters, and the area filter includes the capabilities to perform high-pass, band-pass, low-pass, and wedge filtering techniques. These filters are applied for analyzing satellite multispectral scanner data, airborne visible and infrared imaging spectrometer (AVIRIS) data, gravity data, and the digital elevation models (DEM) data. -from Author

  10. Synthesis of Band Filters and Equalizers Using Microwav FIR Techniques

    SciTech Connect

    Deibele, C.; /Fermilab

    2000-01-01

    It is desired to design a passive bandpass filter with both a linear phase and flat magnitude response within the band and also has steep skirts. Using the properties of both coupled lines and elementary FIR (Finite Impulse Response) signal processing techniques can produce a filter of adequate phase response and magnitude control. The design procedure will first be described and then a sample filter will then be synthesized and results shown.

  11. Detecting and Characterizing Exoplanets with the WFIRST Coronagraph: Colors of Planets in Standard and Designer Bandpasses-SETI

    NASA Astrophysics Data System (ADS)

    Turnbull, Margaret

    The WFIRST mission is now envisioned to include a coronagraph for the purpose of direct detection of nearby exoplanets, including planets known to exist via radial velocity detection and new discoveries. Assuming that starlight rejection sufficient for planet detection (~1e-9) can be achieved, what can be learned about these planets given a realistic spectral resolution and signal-to-noise ratio? We propose to investigate the potential for WFIRST to efficiently discriminate planets from background sources, and to characterize planets in terms of important diagnostic atmospheric features, using broad- and intermediate band color data. We will map out this capability as a function of signal-to-noise ratio, bandpass location, and bandpass width. Our investigation will place emphasis on gas giants, ice giants, and mini-Neptunes (compatible with current AFTA-C baseline performance specifications), as well as a variety of super-Earths (an AFTA-C "stretch" goal). We will explore a variety of compositions, cloud types, phase angles, and (in the case of super-Earths with semi-transparent atmospheres) surface types. Noiseless spectra generated for these model planets will be passed through (a) standard bandpasses for comparison to prior work and (b) filter transmission curves corresponding to bandpasses of 5-20% over the full range of WFIRST's expected bandpass (400 - 1,000 nm). From this, filter combinations will be used to generate planet colors and find filter sets that most efficiently discriminate between planets and background sources, and between planets of different type. We will then repeat this exercise for S/N levels of 1-1,000 in order to (1) explore the true efficacy of broadband measurements in exoplanet studies, and (2) provide an estimate of total required integration time for a compelling WFIRST exoplanet program. To accomplish this, we will use model spectra for mini-Neptunes, and ice and gas giants of varying composition (Hu et al. 2013), and observed

  12. Filters in 2D and 3D Cardiac SPECT Image Processing

    PubMed Central

    Ploussi, Agapi; Synefia, Stella

    2014-01-01

    Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast. PMID:24804144

  13. Piecewise spectrally band-pass for compressive coded aperture spectral imaging

    NASA Astrophysics Data System (ADS)

    Qian, Lu-Lu; Lü, Qun-Bo; Huang, Min; Xiang, Li-Bin

    2015-08-01

    Coded aperture snapshot spectral imaging (CASSI) has been discussed in recent years. It has the remarkable advantages of high optical throughput, snapshot imaging, etc. The entire spatial-spectral data-cube can be reconstructed with just a single two-dimensional (2D) compressive sensing measurement. On the other hand, for less spectrally sparse scenes, the insufficiency of sparse sampling and aliasing in spatial-spectral images reduce the accuracy of reconstructed three-dimensional (3D) spectral cube. To solve this problem, this paper extends the improved CASSI. A band-pass filter array is mounted on the coded mask, and then the first image plane is divided into some continuous spectral sub-band areas. The entire 3D spectral cube could be captured by the relative movement between the object and the instrument. The principle analysis and imaging simulation are presented. Compared with peak signal-to-noise ratio (PSNR) and the information entropy of the reconstructed images at different numbers of spectral sub-band areas, the reconstructed 3D spectral cube reveals an observable improvement in the reconstruction fidelity, with an increase in the number of the sub-bands and a simultaneous decrease in the number of spectral channels of each sub-band. Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 61225024) and the National High Technology Research and Development Program of China (Grant No. 2011AA7012022).

  14. Isotropically sensitive optical filter employing atomic resonance transitions

    DOEpatents

    Marling, John B.

    1981-01-01

    An ultra-high Q isotropically sensitive optical filter or optical detector employing atomic resonance transitions. More specifically, atomic resonance transitions utilized in conjunction with two optical bandpass filters provide an optical detector having a wide field of view (.about.2.pi. steradians) and very narrow acceptance bandwidth approaching 0.01 A. A light signal to be detected is transmitted through an outer bandpass filter into a resonantly absorbing atomic vapor, the excited atomic vapor then providing a fluorescence signal at a different wavelength which is transmitted through an inner bandpass filter. The outer and inner bandpass filters have no common transmission band, thereby resulting in complete blockage of all optical signals that are not resonantly shifted in wavelength by the intervening atomic vapor. Two embodiments are disclosed, one in which the light signal raises atoms contained in the atomic vapor from the ground state to an excited state from which fluorescence occurs, and the other in which a pump laser is used to raise the atoms in the ground state to a first excited state from which the light signal then is resonantly absorbed, thereby raising the atoms to a second excited state from which fluorescence occurs. A specific application is described in which an optical detector according to the present invention can be used as an underwater detector for light from an optical transmitter which could be located in an orbiting satellite.

  15. Compact continuously tunable microwave photonic filters based on cascaded silicon microring resonators

    NASA Astrophysics Data System (ADS)

    Liu, Li; He, Mengying; Dong, Jianji

    2016-03-01

    We propose and experimentally demonstrate a photonic approach to achieving tunable bandpass microwave photonic filters (MPFs) based on cascaded microring resonators (CMRRs). The optical spectrum of the silicon CMRRs could offer two bandpass response to separately filter the optical carrier and one of the sidebands generated by the phase modulation. Thus we could achieve a bandpass MPF. Moreover, as the central frequencies and bandwidths of the two bandpass response can be tuned by adjusting the laser wavelength and voltages applied on one MRR, the central operating frequency or 3-dB bandwidth of the MPF can be continuously tuned in wide ranges respectively. A proof-of-concept experiment illustrates a central frequency tuning range from 19 GHz to 40 GHz, and a wide bandwidth tuning range from 5.5 GHz to 17.5 GHz.

  16. A Quadrupole Band-Pass Filter for a White Proton Source

    NASA Astrophysics Data System (ADS)

    Morrow, Jonathon; Peterson, Jerry

    2009-10-01

    The LANSCE facility at Los Alamos National Laboratory uses a beam of 800 MeV protons as a source of continuous (white) beams of neutrons, used for a wide range of basic and applied science. The same source also provides a white source of protons, which would be very useful for research, if some degree of energy resolution were available. We are designing a quadrupole magnet system that will provide such energy resolution by focusing only the desired momentum onto a sample, with protons of more or less momentum more widely diffused. Results will be given for designs based on simple thin lens optics to understand the criteria and general trends. A full design will require use of magnetic beam transport codes and a specific magnet system.

  17. A Study on Compact Wide Bandpass Filter Using Inter-Digital Resonator

    NASA Astrophysics Data System (ADS)

    Yamamoto, Jumpei; Yasuzumi, Takenori; Uwano, Tomoki; Hashimoto, Osamu

    A new type of the wide-band BPF made up of an inter-digital resonator and parallel-coupled lines was proposed. The bandwidth of the inter-digital resonator becomes wider by increasing the number of fingers. The design of the parallel-coupled line was performed by optimazing the structural parameters so that the bandwidth is the same as that of the inter-digital resonator. The measured results of the combination of above elements for the BPF agreed well with the simulated ones such that the insertion loss is less than 0.67dB and that the sharp skirt characteristics are realized by attenuation poles near the edges of the passband.

  18. Bandpass-resampling effects for the retrieval of surface emissivity.

    PubMed

    Richter, Rudolf; Coll, Cesar

    2002-06-20

    The retrieval of surface emissivity in the 8-14-microm region from remotely sensed thermal imagery requires channel-averaged values of atmospheric transmittance, path radiance, and downwelling sky flux. Band-pass resampling introduces inherent retrieval errors that depend on atmospheric conditions, spectral region, bandwidth, flight altitude, and surface temperature. This simulation study is performed for clear sky conditions and moderate atmospheric water vapor contents. It shows that relative emissivity retrieval errors can reach as much as 3% for broadband sensors (1-2-microm bandwidth) and 0.8% for narrowband instruments (0.15 microm), even for constant surface emissivity. For spectrally varying surface emissivities the relative retrieval error increases for the broadband instrument by approximately 2% in channels with strong emissivity changes of 0.05-0.1. The corresponding retrieval errors for narrowband sensors increase by approximately 3-4%. The channels in the atmospheric window regions with lower transmittance, i.e., 8-8.5 and 12.5-14 microm, are most sensitive to retrieval errors. PMID:12078676

  19. Terahertz filter with tailored passband using multiple phase shifted fiber Bragg gratings.

    PubMed

    Zhou, Shu Fan; Reekie, Laurence; Chan, Hau Ping; Luk, Kwai Man; Chow, Yuk Tak

    2013-02-01

    Transmission filters for the terahertz domain having a shaped bandpass have been modeled and demonstrated. The filter designs were based on the desired filter type and bandwidth, and implemented by cascading quarter wave phase shifted fiber Bragg gratings written in Topas polymer subwavelength fiber. As an example, a 5-pole Chebyshev filter with <3 GHz bandwidth was designed and fabricated. Experimental and simulated results are in good agreement. PMID:23381404

  20. Flexible RF filter using a nonuniform SCISSOR.

    PubMed

    Zhuang, Leimeng

    2016-03-15

    This work presents a flexible radiofrequency (RF) filter using an integrated microwave photonic circuit that comprises a nonuniform side-coupled integrated spaced sequence of resonators (N-SCISSOR). The filter passband can be reconfigured by varying the N-SCISSOR parameters. When employing a dual-parallel Mach-Zechnder modulator, the filter is also able to perform frequency down-conversion. In the experiment, various filter response shapes are shown, ranging from a flat-top band-pass filter to a total opposite high-rejection (>40  dB) notch filter, with a frequency coverage of greater than two octaves. The frequency down-conversion function is also demonstrated. PMID:26977648

  1. Adaptive Spatial Filtering with Principal Component Analysis for Biomedical Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Nagaoka, Ryo; Yamazaki, Rena; Saijo, Yoshifumi

    Photoacoustic (PA) signal is very sensitive to noise generated by peripheral equipment such as power supply, stepping motor or semiconductor laser. Band-pass filter is not effective because the frequency bandwidth of the PA signal also covers the noise frequency. The objective of the present study is to reduce the noise by using an adaptive spatial filter with principal component analysis (PCA).

  2. Adaptive Mallow's optimization for weighted median filters

    NASA Astrophysics Data System (ADS)

    Rachuri, Raghu; Rao, Sathyanarayana S.

    2002-05-01

    This work extends the idea of spectral optimization for the design of Weighted Median filters and employ adaptive filtering that updates the coefficients of the FIR filter from which the weights of the median filters are derived. Mallows' theory of non-linear smoothers [1] has proven to be of great theoretical significance providing simple design guidelines for non-linear smoothers. It allows us to find a set of positive weights for a WM filter whose sample selection probabilities (SSP's) are as close as possible to a SSP set predetermined by Mallow's. Sample selection probabilities have been used as a basis for designing stack smoothers as they give a measure of the filter's detail preserving ability and give non-negative filter weights. We will extend this idea to design weighted median filters admitting negative weights. The new method first finds the linear FIR filter coefficients adaptively, which are then used to determine the weights of the median filter. WM filters can be designed to have band-pass, high-pass as well as low-pass frequency characteristics. Unlike the linear filters, however, the weighted median filters are robust in the presence of impulsive noise, as shown by the simulation results.

  3. Performance measures in the selection of reconstruction filters for SPECT imaging

    SciTech Connect

    Appledorn, C.R.; Oppenheim, B.E.; Wellman, H.N.

    1985-05-01

    Filter selection in SPECT image reconstruction poses an implicit tradeoff between image smoothness, image contrast and noise texture. It is known that the Ramachandran or ramp filter provides the greatest contrast (and resolution) in a reconstructed image at the expense of poor noise handling. In order to improve detection of either hot or cold lesions, practical experience dictates that some image smoothing must be provided. Thus, the question of the ''optimal'' filter selection has been the subject of this investigation. Using an extension of the approach as originally developed by Beck and Metz, the authors derived a figure-of-merit (FOM) that quantifies the performance of the reconstruction algorithm being tested. The FOM can be separated into two components: smoothness factor (SF) which is a measure of noise reduction and contrast factor (CF) which is a measure of the spatial resolution of the filter being tested. Each component is measured separately. The optimum filter should maintain the contrast of the Ramachandran filter (CF = 0.313) but improve the noise handling (SF = 8.86). A variety of commercially available filters were tested: rectangular, Hann, and Butterworth. Also examined were the order of the filter and the interpolation method (nearest-neighbor, linear, and Fourier methods with padding of zeros). The authors found that high order Butterworth filters performed best in maintaining contrast but reducing noise. Using a cutoff frequency of 0.200 (Nyquist = 0.500) and an order of 30, the filter provided a CF = 0.313 and a SF = 30.31. Linear interpolation was marginally better.

  4. Auditory stream segregation using amplitude modulated bandpass noise.

    PubMed

    Nie, Yingjiu; Nelson, Peggy B

    2015-01-01

    The purpose of this study was to investigate the roles of spectral overlap and amplitude modulation (AM) rate for stream segregation for noise signals, as well as to test the build-up effect based on these two cues. Segregation ability was evaluated using an objective paradigm with listeners' attention focused on stream segregation. Stimulus sequences consisted of two interleaved sets of bandpass noise bursts (A and B bursts). The A and B bursts differed in spectrum, AM-rate, or both. The amount of the difference between the two sets of noise bursts was varied. Long and short sequences were studied to investigate the build-up effect for segregation based on spectral and AM-rate differences. Results showed the following: (1). Stream segregation ability increased with greater spectral separation. (2). Larger AM-rate separations were associated with stronger segregation abilities. (3). Spectral separation was found to elicit the build-up effect for the range of spectral differences assessed in the current study. (4). AM-rate separation interacted with spectral separation suggesting an additive effect of spectral separation and AM-rate separation on segregation build-up. The findings suggest that, when normal-hearing listeners direct their attention towards segregation, they are able to segregate auditory streams based on reduced spectral contrast cues that vary by the amount of spectral overlap. Further, regardless of the spectral separation they are able to use AM-rate difference as a secondary/weaker cue. Based on the spectral differences, listeners can segregate auditory streams better as the listening duration is prolonged-i.e., sparse spectral cues elicit build-up segregation; however, AM-rate differences only appear to elicit build-up when in combination with spectral difference cues. PMID:26300831

  5. Thermal control design of the Lightning Mapper Sensor narrow-band spectral filter

    NASA Technical Reports Server (NTRS)

    Flannery, Martin R.; Potter, John; Raab, Jeff R.; Manlief, Scott K.

    1992-01-01

    The performance of the Lightning Mapper Sensor is dependent on the temperature shifts of its narrowband spectral filter. To perform over a 10 degree FOV with an 0.8 nm bandwidth, the filter must be 15 cm in diameter and mounted externally to the telescope optics. The filter thermal control required a filter design optimized for minimum bandpass shift with temperature, a thermal analysis of substrate materials for maximum temperature uniformity, and a thermal radiation analysis to determine the parameter sensitivity of the radiation shield for the filter, the filter thermal recovery time after occultation, and heater power to maintain filter performance in the earth-staring geosynchronous environment.

  6. Test Of A Microwave Amplifier With Superconductive Filter

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

    1995-01-01

    Report describes design and low-temperature tests of low-noise GaAs microwave amplifier combined with microstrip band-pass filter. Two versions of microstrip filter used in alternate tests; in one version, microstrips formed as films of high-transition-temperature superconductor Y/Ba/Cu/O on lanthanum aluminate substrate with gold film as ground plane. Other version identical except microstrips as well as ground plane made of gold, normally conductive.

  7. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations.

    PubMed

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T-C; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators. PMID:27131699

  8. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T.-C.; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators.

  9. Filter Circuit Design by Parallel Genetic Programming

    NASA Astrophysics Data System (ADS)

    Yano, Yuichi; Kato, Toshiji; Inoue, Kaoru; Miki, Mitsunori

    Genetic Programming (GP) is an extension of Genetic Algorithm(GA) to handle more structural problems. In this paper, an approach to filter circuit design by GP is proposed. By designing a gene which includes not only the parameters of consisting elements, but also the structural information of the circuit, it becomes possible to apply the proposed approach to various types of filter circuits. GP depends much on trial and error due to its probabilitic nature. To decrease this uncertainty and ensure the progress of the evolution, Parallel GP with multiple populations with the island model is also proposed. An MPI-based cluster system is used for realization of this parallel computing where each island correspondsd to each node. A lowpass and an asymmetric bandpass filters are designed. One hundred times of trials for multiple populations with and without migrations are tested in the design of lowpass filter to confirm the validity of the proposed method. In the asymmetric bandpass filter design, the results are compared with those of the circuit designed by hand to confirm the effectiveness of the proposed method. The proposed approach is applicable to various types of filter circuits. It can contribute to an automated design procedure, where it would require a expirenced designer if done by hand. It is also possible to obtain a new circuit design which would not be possible if done by hand.

  10. A novel filter bank for biotelemetry.

    PubMed

    Karagözoglu, B

    2001-03-01

    In a multichannel biotelemetry system, signals taken from a patient are distributed along the available frequency range (bandwidth) of the system through frequency-division-multiplexing, and combined into a single composite signal. Biological signals that are limited to low frequencies (below 10 Hz) modulate the frequencies of respective sub-carriers. Other biological signals are carried in amplitude-modulated forms. It is recognized that recovering original signals from a composite signal at the receiver side is a technical challenge when a telemetry system with narrow bandwidth capacity is used, since such a system leaves little frequency spacing between information channels. A filter bank is therefore utilized for recovering biological signals that are transmitted. The filter bank contains filter units comprising switched-capacitor filter integrated circuits. The filters have two distinct and opposing outputs (band-stop (notch) and band-pass). Since most biological signals are at low frequencies, and modulated signals occupy a narrow band around the carrier, notch filters can be used to efficiently stop signals in the narrow frequency range. Once the interim channels are removed, other channels become well separated from each other, and band-pass filters can select them. In the proposed system, efficient filtering of closely packed channels is achieved, with low interference, from neighboring channels. The filter bank is applied to a system that carries four biological signals and a battery status indicator signal. Experimental results reinforce theoretical predictions that the filter bank successfully de-multiplexes closely packed information channels with low crosstalk between them. It is concluded that the proposed filter bank allows utilization of cost-effective multichannel biotelemetry systems that are designed around commercial audio devices, and that it can be readily adapted to a broad range of physiological recording requirements. PMID:11458572

  11. Applications of the magneto-optical filter to stellar pulsation measurements

    NASA Technical Reports Server (NTRS)

    Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.

    1984-01-01

    A proposed method of employing the Cacciani magneto-optical filter (MOF) for stellar seismology studies is described. The method relies on the fact that the separation of the filter bandpasses in the MOF can be changed by varying the level of input power to the filter cells. With the use of a simple servosystem the bandpass of a MOF can be tuned to compensate for the changes in the radial velocity of a star introduced by the orbital motion of the Earth. Such a tuned filter can then be used to record intensity fluctuations through the MOF bandpass over an extended period of time for each given star. Also, the use of a two cell version of the MOF makes it possible to alternately chop between the bandpass located in the stellar line wing and a second bandpass located in the stellar continuum. Rapid interchange between the two channels makes it possible for atmospheric-introduced noise to be removed from the time series.

  12. Applications of the magneto-optical filter to stellar pulsation measurements

    NASA Technical Reports Server (NTRS)

    Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk, Steven

    1986-01-01

    A proposed method of employing the Cacciani magneto-optical filter (MOF) for stellar seismology studies is described. The method relies on the fact that the separation of the filter bandpasses in the MOF can be changed by varying the level of input power to the filter cells. With the use of a simple servosystem the bandpass of a MOF can be tuned to compensate for the changes in the radial velocity of a star introduced by the orbital motion of the earth. Such a tuned filter can then be used to record intensity fluctuations through the MOF bandpass over an extended period of time for each given star. Also, the use of a two cell version of the MOF makes it possible to alternately chop between the bandpass located in the stellar line wing and a second bandpass located in the stellar continuum. Rapid interchange between the two channels makes it possible for atmospheric-introduced noise to be removed from the time series.

  13. Wideband tunable optoelectronic oscillator based on a phase modulator and a tunable optical filter.

    PubMed

    Xie, Xiaopeng; Zhang, Cheng; Sun, Tao; Guo, Peng; Zhu, Xiaoqi; Zhu, Lixin; Hu, Weiwei; Chen, Zhangyuan

    2013-03-01

    A widely tunable optoelectronic oscillator (OEO) based on a broadband phase modulator and a tunable optical bandpass filter is proposed and experimentally demonstrated. A tunable range from 4.74 to 38.38 GHz is realized by directly tuning the bandwidth of the optical bandpass filter. To the best of our knowledge, this is the widest fundamental frequency tunable range ever achieved by an OEO. The phase noise performance of the generated signal is also investigated. The single-sideband phase noise is below -120 dBc/Hz at an offset of 10 KHz within the whole tunable range. PMID:23455255

  14. Filter-free wavelength converter using Sagnac loop and delayed interferometer

    NASA Astrophysics Data System (ADS)

    Tsuji, K.; Yamaguchi, T.; Onodera, N.; Saruwatari, M.

    2006-01-01

    A filter-free fiber-XPM-based wavelength converter is proposed and experimentally demonstrated without conventional bandpass optical filters used to filter out the converted signal. The converter is constructed with a propagation-diversity Sagnac loop to separate a converted signal from a pump signal and a delayed interferometer to covert the XPM signal into intensity modulation. We show that 10-Gbit/s input signals are successfully converted to signals with allotted wavelengths by our proposed scheme.

  15. Far-infrared filters utilizing small particle scattering and antireflection coatings

    NASA Technical Reports Server (NTRS)

    Armstrong, K. R.; Low, F. J.

    1974-01-01

    High-transmission, low-pass scatter filters for blocking at wavelengths from 3.5 to 50 microns and single-layer antireflection coatings for optical materials used in the 25- to 300-micron region of the spectrum are described. The application of both techniques to liquid-He-cooled filters permits the construction of efficient low-pass and medium-width bandpass filters for use throughout the far infrared.

  16. Comparison of the Richardson-Lucy method and a classical approach for spectrometer bandpass correction

    NASA Astrophysics Data System (ADS)

    Eichstädt, S.; Schmähling, F.; Wübbeler, G.; Anhalt, K.; Bünger, L.; Krüger, U.; Elster, C.

    2013-04-01

    Bandpass correction in spectrometer measurements using monochromators is often necessary in order to obtain accurate measurement results. The classical approach of spectrometer bandpass correction is based on local polynomial approximations and the use of finite differences. Here we compare this approach with an extension of the Richardson-Lucy method, which is well known in image processing, but has not been applied to spectrum bandpass correction yet. Using an extensive simulation study and a practical example, we demonstrate the potential of the Richardson-Lucy method. In contrast to the classical approach, it is robust with respect to wavelength step size and measurement noise. In almost all cases the Richardson-Lucy method turns out to be superior to the classical approach both in terms of spectrum estimate and its associated uncertainties.

  17. Achieving all-dielectric metamaterial band-pass frequency selective surface via high-permittivity ceramics

    NASA Astrophysics Data System (ADS)

    Li, Liyang; Wang, Jiafu; Ma, Hua; Wang, Jun; Feng, Mingde; Du, Hongliang; Yan, Mingbao; Zhang, Jieqiu; Qu, Shaobo; Xu, Zhuo

    2016-03-01

    In this paper, we propose the design of all-dielectric metamaterial band-pass frequency selective surfaces (FSSs) using high-permittivity ceramics based on effective medium theory and dielectric resonator theory. The band-pass response can be determined by the permittivity of the dielectric material, the periodicity, and geometrical shape of the dielectric unit cell. As an example, a band-pass FSS composed of H shaped ceramic resonators is demonstrated. Both the simulation and experiment results show that the FSS can achieve a pass band in X-band. Since such FSSs are made of low-loss high-permittivity ceramics, they are of important application values, especially in high-temperature, high-power environments. The design method can be readily extended to the design of FSSs in other frequencies.

  18. Stack filters

    NASA Astrophysics Data System (ADS)

    Wendt, P. D.; Coyle, E. J.; Gallagher, N. C., Jr.

    1986-08-01

    A large class of easily implemented nonlinear filters called stack filters are discussed which includes the rank order operators in addition to the compositions of morphological operators. Techniques similar to those used to determine the root signal behavior of median filters are employed to study the convergence properties of the filters, and necessary conditions for a stack filter to preserve monotone regions or edges in signals, and the output distribution of the filters, are obtained. Among the stack filters of window width three are found asymmetric median filters in which one removes only positive going edges, the other removes only negative going edges, while the median filter removes impulses of both signs.

  19. Metal-mesh optical filter technology for mid-IR, far-IR, and submillimeter

    NASA Astrophysics Data System (ADS)

    McGovern, William R.; Swinehart, Philip R.; Hogue, Eric L.; Daughton, David R.; DeLombard, Jay V.

    2012-06-01

    The innovative, high transmission band-pass filter technology presented here for the mid infrared (IR), terahertz (THz) and submillimeter ranges can tolerate cryogenic temperatures (down to 4K and below), are radiation-hard, vacuum-compatible and vibration-tolerant making them launch-capable and durable for potential space applications. In addition, Lake Shore band-pass filters (BPF) are light weight, as they employ no heavy substrates, nor have any vibronic bands due to polymer support layers. The filters are less than 2 mm thick (mostly the mounting frame) which allows insertion into tight spaces and standard filter wheels. The thin, light weight, vacuum compatible design can be incorporated into almost any detector setup. Filters are available for quick delivery in 29 standard center wavelengths (CWL) with 4 standard diameter sizes, up to 40mm inner diameter (ID).

  20. Low-power Gm-C filter employing current-reuse differential difference amplifiers

    DOE PAGESBeta

    Mincey, John S.; Briseno-Vidrios, Carlos; Silva-Martinez, Jose; Rodenbeck, Christopher T.

    2016-08-10

    This study deals with the design of low-power, high performance, continuous-time filters. The proposed OTA architecture employs current-reuse differential difference amplifiers in order to produce more power efficient Gm-C filter solutions. To demonstrate this, a 6th order low-pass Butterworth filter was designed in 0.18 m CMOS achieving a 65-MHz -3-dB frequency, an in-band input-referred third-order intercept point of 12.0 dBm, and an input referred noise density of 40 nV/Hz1=2, while only consuming 8.07 mW from a 1.8 V supply and occupying a total chip area of 0.21 mm2 with a power consumption of only 1.19 mW per pole.

  1. Single cavity filters on end-faces of optical fibers

    NASA Astrophysics Data System (ADS)

    Meister, Stefan; Schweda, Dawid; Dziedzina, Marcus; Al-Saadi, Aws; Franke, Bülent A.; Scharfenorth, Chris; Grimm, Bernd; Dufft, Daniela; Schrader, Sigurd K.; Eichler, Hans J.

    2010-02-01

    We have developed thin film Fabry-Perot filters directly coated on optical fibers to archive a high level of integration with a reduction of optical elements. Such band-pass filters can be used in fiber optical sensor systems, and for fiber communication, e.g. CWDM applications. The filters cavities consist of a single spacer and two dielectric mirrors. The dielectric mirrors are deposited by PVD directly on end-faces of single-mode optical fibers. Dielectric as well as polymeric materials were applied as the spacer layer. Polymeric spacer layers were deposited by dip coating. The influence of the mirror reflectivity on the transmission band of the Fabry-Perot filters was investigated. Furthermore, the optical performance of filters with first order (λ/2) as well as higher order spacers was analyzed. The experimental results are compared with numerical analysis of Fabry-Perot cavities on the end-face of cylindrical waveguides. The spectral characteristic of the filters are calculated using a software solving Maxwelĺs equations by a FDTD method. The layer design of the filters and the deposition process were optimized for maximum transmission and narrow bandwidth of the transmission peak. Passive band-pass filters on fiber end-faces were designed, fabricated and characterized for transmission wavelengths of 945 nm, 1300 nm, as well as 1550 nm. Bandwidths as narrow as 1 nm could be achieved for 945 nm.

  2. Multi-frequency weak signal detection based on wavelet transform and parameter compensation band-pass multi-stable stochastic resonance

    NASA Astrophysics Data System (ADS)

    Han, Dongying; li, Pei; An, Shujun; Shi, Peiming

    2016-03-01

    In actual fault diagnosis, useful information is often submerged in heavy noise, and the feature information is difficult to extract. A novel weak signal detection method aimed at the problem of detecting multi-frequency signals buried under heavy background noise is proposed based on wavelet transform and parameter compensation band-pass multi-stable stochastic resonance (SR). First, the noisy signal is processed by parameter compensation, with the noise and system parameters expanded 10 times to counteract the effect of the damping term. The processed signal is decomposed into multiple signals of different scale frequencies by wavelet transform. Following this, we adjust the size of the scaled signals' amplitudes and reconstruct the signals; the weak signal frequency components are then enhanced by multi-stable stochastic resonance. The enhanced components of the signal are processed through a band-pass filter, leaving the enhanced sections of the signal. The processed signal is analyzed by FFT to achieve detection of the multi-frequency weak signals. The simulation and experimental results show that the proposed method can enhance the signal amplitude, can effectively detect multi-frequency weak signals buried under heavy noise and is valuable and usable for bearing fault signal analysis.

  3. Isotropically sensitive optical filter employing atomic resonance transitions

    DOEpatents

    Marling, J.B.

    An ultra-high Q isotropically sensitive optical filter or optical detector is disclosed employing atomic resonance transitions. More specifically, atomic resonance transitions utilized in conjunction with two optical bandpass filters provide an optical detector having a wide field of view (approx. 2 ..pi.. steradians) and very narrow acceptance bandwidth approaching 0.01A. A light signal to be detected is transmitted through an outer bandpass filter into a resonantly absorbing atomic vapor, the excited atomic vapor than providing a fluorescence signal at a different wavelength which is transmitted through an inner bandpass filters have no common transmission band, therby resulting in complete blockage of all optical signals that are not resonantly shifted in wavelength by the intervening atomic vapor. Two embodiments are disclosed, one in which the light signal raises atoms contained in the atomic vapor from the ground state to an excited state from which fluorescence occurs, and the other in which a pump laser is used to raise the atoms in the ground state to a first excited state from which the light signal then is resonantly absorbed, thereby raising the atoms to a second excited state from which fluorescence occurs. A specific application is described in which an optical detector according to the present invention can be located in an orbiting satellite.

  4. Bandpass Sampling--An Opportunity to Stress the Importance of In-Depth Understanding

    ERIC Educational Resources Information Center

    Stern, Harold P. E.

    2010-01-01

    Many bandpass signals can be sampled at rates lower than the Nyquist rate, allowing significant practical advantages. Illustrating this phenomenon after discussing (and proving) Shannon's sampling theorem provides a valuable opportunity for an instructor to reinforce the principle that innovation is possible when students strive to have a complete…

  5. Band-pass design optimization of piezoelectric cantilever bimorph energy harvester

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Williams, Keith A.

    2011-03-01

    Piezoelectric energy harvesting has become a feasible method for powering micro portable electronics and wireless sensor networks by converting ambient vibration energy into electrical energy. As a thumb of rule, it is critical to tune the resonant frequency of the generator to the frequency of the environmental vibrations in order to induce the maximum structural deformation and then the maximum converted electrical energy through piezoelectric effect. However, it is well-known that the ambient vibrations are not usually fixed in only one single frequency and could span over a limited frequency band. In this paper, a band-pass design optimization of piezoelectric cantilever bimorph (PCB) energy harvester is presented based on the system transfer function of the PCB generator presented in a previous literature. For such an energy harvester, a group of PCB with dimensions appropriately selected can be integrated into a band-pass energy harvester working over a limited frequency band if the dimensions of piezoelectric bimorphs and proof masses are appropriately chosen. Further, the finite element analysis (FEA) of such a band-pass energy harvester is performed in ANSYS to validate the theoretical proposal. The result shows that the band-pass design optimization leads to a piezoelectric generator working over a certain frequency band while keeping outputting the relatively stable open-circuit voltage.

  6. Simultaneous correction of bandpass and stray-light effects in array spectroradiometer data

    NASA Astrophysics Data System (ADS)

    Nevas, Saulius; Wübbeler, Gerd; Sperling, Armin; Elster, Clemens; Teuber, Annette

    2012-04-01

    A method for the simultaneous correction of bandpass and stray-light effects in array spectroradiometer data is presented. The method is based on the inversion of the instrument matrix of a device determined with the help of tuneable lasers. By applying the Tikhonov regularization technique, a straightforward correction of the measurement results is possible.

  7. Polarization and angle insensitive dual-band bandpass frequency selective surface using all-dielectric metamaterials

    NASA Astrophysics Data System (ADS)

    Yu, Fei; Wang, Jun; Wang, Jiafu; Ma, Hua; Du, Hongliang; Xu, Zhuo; Qu, Shaobo

    2016-04-01

    In this paper, we demonstrate a dual-band bandpass all-dielectric frequency selective surface (FSS), the building elements of which are high-permittivity ceramic particles rather than metallic patterns. With proper structural design and parameter adjustment, the resonant frequency can be tuned at will. Dual-band bandpass response can be realized due to the coupling between electric and magnetic resonances. As an example, a dual-band bandpass FSS is designed in Ku band, which is composed of two-dimensional periodic arrays of complementary quatrefoil structures (CQS) cut from dielectric plates. Moreover, cylindrical dielectric resonators are introduced and placed in the center of each CQS to broaden the bandwidth and to sharpen the cut-off frequency. Theoretical analysis shows that the bandpass response arises from impedance matching caused by electric and magnetic resonances. In addition, effective electromagnetic parameters and dynamic field distributions are presented to explain the mechanism of impedance matching. The proposed FSS has the merits of polarization independence, stable transmission, and sharp roll-off frequency. The method can also be used to design all-dielectric FSSs with continuum structures at other frequencies.

  8. Application of high-pass filtering techniques on gravity and magnetic data of the eastern Qattara Depression area, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Zahra, Hesham Shaker; Oweis, Hesham T.

    2016-06-01

    In this work, a reconnaissance study is presented to delineate the subsurface tectonics and lithological inferences of the eastern area of Qattara Depression using the Bouguer gravity and aeromagnetic data. To achieve this goal, several transformation techniques and filtering processes are accomplished on these maps. At first, the total intensity aeromagnetic map is processed through the application of reduction to the magnetic north pole technique. The fast Fourier transform is carried out on the gravity and RTP magnetic data for establishing and defining the residual (shallow) sources. The frequency high-pass filtering is used to enhance the anomaly wavelengths associated with the shallow sources. The used processing techniques are the polynomial surface fitting enhancement, Laplacian, Strike Filtering, Enhancement Utilization, Suppression Utilization, Butterworth Filtering Utilization, Butterworth high-pass filter, Euler's deconvolution and forward modeling. The equivalent depths of the isolated short wavelength anomalies are 0.759 and 0.340 km below the flight surface, and the depths of the intermediate wavelength anomalies are 1.28 and 2.00 km for the gravity and magnetic data, respectively. Finally, the quantitative interpretations of the Bouguer gravity and RTP magnetic maps of the study area, reflect the occurrence of the various types of structures and their components. The main tectonic deformations of the study area have NNW-SSE, NNE-SSW, NE-SW, NW-SE and E-W trends.

  9. Input-Feedforward Two-Path Band-Pass Delta-Sigma Modulator Based on Horizontal or Vertical Opamp Sharing Technique

    NASA Astrophysics Data System (ADS)

    Waki, Naoya; Sato, Hiroki; Hyogo, Akira; Sekine, Keitaro

    In this paper, horizontal (where an opamp is shared in two adjacent stages) and vertical (where an opamp is shared across two paths) opamp sharing techniques for a two-path band-pass (BP) ΔΣ modulator are described, and input-feedforward two-path fourth-order BP ΔΣ modulators that have only two opamps are proposed. The proposed modulators are based on the horizontal or vertical opamp sharing technique. They can be realized with both a summation circuit using a switched capacitor (SC) network and a second-order high-pass filter (HPF) with a horizontal shared opamp or a double-sampling first-order HPF with a vertical shared opamp, which are based on an SC first-order HPF with an opamp. These techniques can reduce the number of opamps with no additional component and the chip area as well as realize lower power consumption.

  10. Surface plasmonic enhanced polarimetric longwave infrared photodetection with band pass spectral filtering

    NASA Astrophysics Data System (ADS)

    Vasinajindakaw, Puminun; Vaillancourt, Jarrod; Gu, Guiru; Lu, Xuejun

    2012-06-01

    In this paper, we report a surface plasmonic enhanced polarimetric longwave infrared (LWIR) photodetector. Polarization-selective detection of LWIR incidence with different polarizations is achieved at different plasmonic resonant modes. Band-pass spectral filtering is also provided at the plasmonic resonant modes by the plasmonic enhancement. The extinction ratio (ER) of the polarimetric detection and its limiting factor is discussed.

  11. Terahertz wave filter based on cinquefoil photonic crystal

    NASA Astrophysics Data System (ADS)

    Sun, Chao; Li, Jiu-sheng

    2012-03-01

    There are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, terahertz wave communications, and plasma diagnostics. For potential applications, the functional devices, such as beam polarizers, modulators and filters, are crucuial components for a terahertz system. As a dispensable device for ultrafast information processing and interconnection of terahertz wave communication, terahertz wave filter has attracted considerable attention. In this paper, we design the terahertz wave filter structure based on three kinds of photonic crystals structures. The finite-difference time-domain (FDTD) has been employed to analysis the performances of these terahertz wave filters. The simulation results show that these designed filters exhibit excellent transmission performance such as high transmission at the central frequency, adjustable bandpass, and good rejection of the sideband frequencies. Three kinds of compact and integrated terahertz wave filters are obtained.

  12. Terahertz wave filter based on cinquefoil photonic crystal

    NASA Astrophysics Data System (ADS)

    Sun, Chao; Li, Jiu-sheng

    2011-11-01

    There are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, terahertz wave communications, and plasma diagnostics. For potential applications, the functional devices, such as beam polarizers, modulators and filters, are crucuial components for a terahertz system. As a dispensable device for ultrafast information processing and interconnection of terahertz wave communication, terahertz wave filter has attracted considerable attention. In this paper, we design the terahertz wave filter structure based on three kinds of photonic crystals structures. The finite-difference time-domain (FDTD) has been employed to analysis the performances of these terahertz wave filters. The simulation results show that these designed filters exhibit excellent transmission performance such as high transmission at the central frequency, adjustable bandpass, and good rejection of the sideband frequencies. Three kinds of compact and integrated terahertz wave filters are obtained.

  13. Spectral and Wavefront Error Performance of WFIRST/AFTA Prototype Filters

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel; Seide, Laurie; Marx, Cathy; Pasquale, Bert; McMann, Joseph; Hagopian, John; Dominguez, Margaret; Gong, Qian; Morey, Peter

    2016-01-01

    The Cycle 5 design baseline for the Wide-Field Infrared Survey Telescope Astrophysics Focused Telescope Assets (WFIRSTAFTA) instrument includes a single wide-field channel (WFC) instrument for both imaging and slit-less spectroscopy. The only routinely moving part during scientific observations for this wide-field channel is the element wheel (EW) assembly. This filter-wheel assembly will have 8 positions that will be populated with 6 bandpass filters, a blank position, and a Grism that will consist of a three-element assembly to disperse the full field with an undeviated central wavelength for galaxy redshift surveys. All filter elements in the EW assembly will be made out of fused silica substrates (110 mm diameter) that will have the appropriate bandpass coatings according to the filter designations (Z087, Y106, J129, H158, F184, W149 and Grism). This paper presents and discusses the performance (including spectral transmission and reflectedtransmitted wavefront error measurements) of a subset of bandpass filter coating prototypes that are based on the WFC instrument filter compliment. The bandpass coating prototypes that are tested in this effort correspond to the Z087, W149, and Grism filter elements. These filter coatings have been procured from three different vendors to assess the most challenging aspects in terms of the in-band throughput, out of band rejection (including the cut-on and cutoff slopes), and the impact the wavefront error distortions of these filter coatings will have on the imaging performance of the de-field channel in the WFIRSTAFTA observatory.

  14. Performance of a Y-Ba-Cu-O superconducting filter/GaAs low noise amplifier hybrid circuit

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

    1992-01-01

    A superconducting 7.3 GHz two-pole microstrip bandpass filter and a GaAs low noise amplifier (LNA) were combined into a hybrid circuit and characterized at liquid nitrogen temperatures. This superconducting/seismology circuit's performance was compared to a gold filter/GaAs LNA hybrid circuit. The superconducting filter/GaAs LNA hybrid circuit showed higher gain and lower noise figure than its gold counterpart.

  15. Performance of a Y-Ba-Cu-O superconducting filter/GaAs low noise amplifier hybrid circuit

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

    1992-01-01

    A superconducting 7.3 GHz two-pole microstrip bandpass filter and a GaAs low noise amplifier (LNA) were combined into an active circuit and characterized at liquid nitrogen temperatures. This superconducting/semiconducting circuit's performance was compared to a gold filter/GaAs LNA hybrid circuit. The superconducting filter/GaAs LNA hybrid circuit showed higher gain and lower noise figure than its gold counterpart.

  16. Development of filter exchangeable 3CCD camera for multispectral imaging acquisition

    NASA Astrophysics Data System (ADS)

    Lee, Hoyoung; Park, Soo Hyun; Kim, Moon S.; Noh, Sang Ha

    2012-05-01

    There are a lot of methods to acquire multispectral images. Dynamic band selective and area-scan multispectral camera has not developed yet. This research focused on development of a filter exchangeable 3CCD camera which is modified from the conventional 3CCD camera. The camera consists of F-mounted lens, image splitter without dichroic coating, three bandpass filters, three image sensors, filer exchangeable frame and electric circuit for parallel image signal processing. In addition firmware and application software have developed. Remarkable improvements compared to a conventional 3CCD camera are its redesigned image splitter and filter exchangeable frame. Computer simulation is required to visualize a pathway of ray inside of prism when redesigning image splitter. Then the dimensions of splitter are determined by computer simulation which has options of BK7 glass and non-dichroic coating. These properties have been considered to obtain full wavelength rays on all film planes. The image splitter is verified by two line lasers with narrow waveband. The filter exchangeable frame is designed to make swap bandpass filters without displacement change of image sensors on film plane. The developed 3CCD camera is evaluated to application of detection to scab and bruise on Fuji apple. As a result, filter exchangeable 3CCD camera could give meaningful functionality for various multispectral applications which need to exchange bandpass filter.

  17. A review of metal mesh filters

    NASA Astrophysics Data System (ADS)

    Ade, Peter A. R.; Pisano, Giampaolo; Tucker, Carole; Weaver, Samuel

    2006-06-01

    The Astronomical Instrumentation Group at Cardiff University has been developing metal mesh optical filters for more than 30 years, which are currently in use in many ground-, balloon- and space-based instruments. Here we review the current state of the art with respect to these quasi-optical components (low-pass, high-pass and band-pass filters, dichroics and beam-dividers) as developed for the FIR and sub-millimetre wavelength region. We compare performance data with various modelling tools (HFSS, transmission line theory or Floquet mode analysis). These models assist with our understanding of the behaviour of these filters when used at non-normal incidence or in the diffraction region of the grid structures. Interesting artefacts, such as the Wood anomalies and behaviour with S and P polarisations, which dictate the usage of these components in polarisation sensitive instruments, will be discussed.

  18. Disk filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  19. Disk filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  20. An R-peak detection method that uses an SVD filter and a search back system.

    PubMed

    Jung, Woo-Hyuk; Lee, Sang-Goog

    2012-12-01

    In this paper, we present a method for detecting the R-peak of an ECG signal by using an singular value decomposition (SVD) filter and a search back system. The ECG signal was detected in two phases: the pre-processing phase and the decision phase. The pre-processing phase consisted of the stages for the SVD filter, Butterworth High Pass Filter (HPF), moving average (MA), and squaring, whereas the decision phase consisted of a single stage that detected the R-peak. In the pre-processing phase, the SVD filter removed noise while the Butterworth HPF eliminated baseline wander. The MA removed the remaining noise of the signal that had gone through the SVD filter to make the signal smooth, and squaring played a role in strengthening the signal. In the decision phase, the threshold was used to set the interval before detecting the R-peak. When the latest R-R interval (RRI), suggested by Hamilton et al., was greater than 150% of the previous RRI, the method of detecting the R-peak in such an interval was modified to be 150% or greater than the smallest interval of the two most latest RRIs. When the modified search back system was used, the error rate of the peak detection decreased to 0.29%, compared to 1.34% when the modified search back system was not used. Consequently, the sensitivity was 99.47%, the positive predictivity was 99.47%, and the detection error was 1.05%. Furthermore, the quality of the signal in data with a substantial amount of noise was improved, and thus, the R-peak was detected effectively. PMID:22922087

  1. Simulator spectral characterization using balloon calibrated solar cells with narrow band pass filters

    NASA Technical Reports Server (NTRS)

    Goodelle, G. S.; Brooks, G. R.; Seaman, C. H.

    1981-01-01

    The development and implementation of an instrument for spectral measurement of solar simulators for testing solar cell characteristics is reported. The device was constructed for detecting changes in solar simulator behavior and for comparing simulator spectral irradiance to solar AM0 output. It consists of a standard solar cell equipped with a band pass filter narrow enough so that, when flown on a balloon to sufficient altitude along with sufficient numbers of cells, each equipped with filters of different bandpass ratings, the entire spectral response of the standard cell can be determined. Measured short circuit currents from the balloon flights thus produce cell devices which, when exposed to solar simulator light, have a current which does or does not respond as observed under actual AM0 conditions. Improvements of the filtered cells in terms of finer bandpass filter tuning and measurement of temperature coefficients are indicated.

  2. Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures.

    PubMed

    Horie, Yu; Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Faraon, Andrei

    2016-05-30

    We propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-Pérot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250nm around λ = 1550nm (Δλ/λ = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwiched metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling. PMID:27410093

  3. Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures

    NASA Astrophysics Data System (ADS)

    Horie, Yu; Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Faraon, Andrei

    2016-05-01

    We propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-P\\'erot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250 nm around {\\lambda} = 1550 nm ({\\Delta}{\\lambda}/{\\lambda} = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwiched metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling.

  4. Photonic aided bandpass sampling in coherent phase modulated radio-over-fiber links

    NASA Astrophysics Data System (ADS)

    Cao, Minghua; Li, Jianqiang; Dai, Jian; Dai, Yitang; Yin, Feifei; Zhou, Yue; Xu, Kun

    2016-06-01

    We have experimentally presented a digital coherent receiver employing photonic aided bandpass sampling technology for phase-modulated radio-over-fiber (RoF) links. An optical intensity modulator (IM) is utilized as the bandpass sampler which performs encoded on-off keyed pulse sequence on the optical local oscillator. Quaternary Phase Shift Keying (QPSK) modulated data signal with 20 MHz bandwidth at 5.2 GHz, 10.2 GHz and 15.2 GHz RF carrier frequency is experimentally demonstrated to be successfully detected by using balanced photodiodes (BPDs) with only 800 MHz analog bandwidth. It demonstrates that the required analog bandwidth of BPDs and ADCs can be dramatically reduced in a direct sampled coherent RoF communications system.

  5. Computer-aided design of millimeter-wave E-plane filters

    NASA Astrophysics Data System (ADS)

    Shih, Y.-C.; Itoh, T.; Bui, L. Q.

    1983-02-01

    A computer-aided design (CAD) algorithm has been developed for a class of E-plane bandpass filters. The analysis portion of the algorithm is based on the residue-calculus technique and a generalized scattering parameter method. It is mathematically exact and numerically very efficient. Filters designed with this method have been fabricated and tested in Ka-band. Good agreement with design has been obtained.

  6. Water Filters

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Aquaspace H2OME Guardian Water Filter, available through Western Water International, Inc., reduces lead in water supplies. The filter is mounted on the faucet and the filter cartridge is placed in the "dead space" between sink and wall. This filter is one of several new filtration devices using the Aquaspace compound filter media, which combines company developed and NASA technology. Aquaspace filters are used in industrial, commercial, residential, and recreational environments as well as by developing nations where water is highly contaminated.

  7. Digital linearization of multi-carrier RF link with photonic bandpass sampling.

    PubMed

    Dai, Yitang; Liang, Xiaodong; Yin, Feifei; Zhou, Yue; Zhang, Junyi; Yu, Lan; Li, Jianqiang; Xu, Kun

    2015-09-01

    Due to the capacity in simultaneously down-converting and receiving ultra-wideband, multi-carrier radio frequency (RF) or microwave signals, the photonic bandpass sampling has found more and more applications in multi-carrier communication, frequency-agile coherent radar, compressive sensing, etc. The nonlinear transfer during the electronics-to-optics conversion results in distortions, which are bandpass sampled and frequency-folded within the first Nyquist zone, together with the target signals. Because of the multi-octave-span operation, all nonlinearities must be considered besides the usually-concerned third-order inter-modulation distortion (IMD3). We show theoretically that a photonic bandpass sampling link is equivalent to a baseband digital nonlinear link, and then propose a corresponding linearization scheme for the output signal. Such digital linearization is capable of suppressing all types of distortions. Both numerical and experimental examples are demonstrated, where all of the 3rd-order nonlinearities, including the internal and external IMD3, the cross modulation, and 3rd-order harmonics, are well eliminated. PMID:26368420

  8. Biological Filters.

    ERIC Educational Resources Information Center

    Klemetson, S. L.

    1978-01-01

    Presents the 1978 literature review of wastewater treatment. The review is concerned with biological filters, and it covers: (1) trickling filters; (2) rotating biological contractors; and (3) miscellaneous reactors. A list of 14 references is also presented. (HM)

  9. Metallic Filters

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Filtration technology originated in a mid 1960's NASA study. The results were distributed to the filter industry, an HR Textron responded, using the study as a departure for the development of 421 Filter Media. The HR system is composed of ultrafine steel fibers metallurgically bonded and compressed so that the pore structure is locked in place. The filters are used to filter polyesters, plastics, to remove hydrocarbon streams, etc. Several major companies use the product in chemical applications, pollution control, etc.

  10. Measuring Redshifts of Emission-line Galaxies Using Ramp Filters

    NASA Astrophysics Data System (ADS)

    Lesser, Ryan William; Bohman, John; McNeff, Mathew; Holden, Marcus; Moody, Joseph; Joner, Michael D.; Barnes, Jonathan

    2016-01-01

    Photometric redshifts are routinely obtained for galaxies without emission using broadband photometry. It is possible in theory to derive reasonably accurate (< 200 km/sec) photometric redshift values for emission-line objects using "ramp" filters with a linearly increasing/decreasing transmission through the bandpass. To test this idea we have obtained a set of filters tuned for isolating H-alpha at a redshift range of 0-10,000 km/sec. These filters consist of two that vary close to linearly in transmission, have opposite slope, and cover the wavelength range from 655nm - 685nm, plus a Stromgren y and 697nm filter to measure the continuum. Redshifts are derived from the ratio of the ramp filters indices after the continuum has been subtracted out. We are finishing the process of obtaining photometric data on a set of about 100 galaxies with known redshift to calibrate the technique and will report on our results.

  11. Water Filters

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A compact, lightweight electrolytic water filter generates silver ions in concentrations of 50 to 100 parts per billion in the water flow system. Silver ions serve as effective bactericide/deodorizers. Ray Ward requested and received from NASA a technical information package on the Shuttle filter, and used it as basis for his own initial development, a home use filter.

  12. FILTER TREATMENT

    DOEpatents

    Sutton, J.B.; Torrey, J.V.P.

    1958-08-26

    A process is described for reconditioning fused alumina filters which have become clogged by the accretion of bismuth phosphate in the filter pores, The method consists in contacting such filters with faming sulfuric acid, and maintaining such contact for a substantial period of time.

  13. Multispectral Filter Arrays: Recent Advances and Practical Implementation

    PubMed Central

    Lapray, Pierre-Jean; Wang, Xingbo; Thomas, Jean-Baptiste; Gouton, Pierre

    2014-01-01

    Thanks to some technical progress in interferencefilter design based on different technologies, we can finally successfully implement the concept of multispectral filter array-based sensors. This article provides the relevant state-of-the-art for multispectral imaging systems and presents the characteristics of the elements of our multispectral sensor as a case study. The spectral characteristics are based on two different spatial arrangements that distribute eight different bandpass filters in the visible and near-infrared area of the spectrum. We demonstrate that the system is viable and evaluate its performance through sensor spectral simulation. PMID:25407904

  14. Microwave photonic interference mitigation filter based on semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Xu, Enming; Zhang, Xinliang; Zhou, Lina; Zhang, Yu; Yu, Yuan; Wang, Fei; Huang, Dexiu

    2009-11-01

    A microwave photonic interference mitigation filter is proposed and experimentally demonstrated. The structure is based on a recirculating delay line loop comprising a semiconductor optical amplifier (SOA) and a tunable narrowband optical filter. Converted signal used as negative tap is generated through wavelength conversion employing cross-gain modulation of amplified spontaneous emission spectrum of the SOA. The converted signal circulating in the RDL loop realizes a high quality factor (Q) response after photo-detection. A bandpass response with negative coefficients combined with a broadband allpass response achieves a notch response with flat passband.

  15. Digital Filter ASIC for NASA Deep Space Radio Science

    NASA Technical Reports Server (NTRS)

    Kowalski, James E.

    1995-01-01

    This paper is about the implementation of an 80 MHz, 16-bit, multi-stage digital filter to decimate by 1600, providing a 50 kHz output with bandpass ripple of less than +/-0.1 dB. The chip uses two decimation by five units and six decimations by two executed by a single decimation by two units. The six decimations by two consist of six halfband filters, five having 30-taps and one having 51-taps. Use of a 16x16 register file for the digital delay lines enables implementation in the Vitesse 350K gate array.

  16. Tailoring of the Brillouin gain for on-chip widely tunable and reconfigurable broadband microwave photonic filters.

    PubMed

    Choudhary, Amol; Aryanfar, Iman; Shahnia, Shayan; Morrison, Blair; Vu, Khu; Madden, Stephen; Luther-Davies, Barry; Marpaung, David; Eggleton, Benjamin J

    2016-02-01

    An unprecedented Brillouin gain of 44 dB in a photonic chip enables the realization of broadly tunable and reconfigurable integrated microwave photonic filters. More than a decade bandwidth reconfigurability from 30 up to 440 MHz, with a passband ripple <1.9  dB is achieved by tailoring the Brillouin pump. The filter central frequency is continuously tuned up to 30 GHz with no degradation of the passband response, which is a major improvement over electronic filters. Furthermore, we demonstrate pump tailoring to realize multiple bandpass filters with different bandwidths and central frequencies, paving the way for multiple on-chip microwave filters and channelizers. PMID:26907391

  17. Novel Utilization of Terminators in the Design of Biologically Adjustable Synthetic Filters.

    PubMed

    Lin, Mei-Ting; Wang, Chun-Ying; Xie, Hui-Juan; Cheung, Chantal Hoi Yin; Hsieh, Chiao-Hui; Juan, Hsueh-Fen; Chen, Bor-Sen; Lin, Che

    2016-05-20

    Terminators, which signal the end of transcription processes, are typically placed behind the last coding sequence of an operon to prevent interference between transcript units in most biologically synthetic systems. Here, we seek to extend the usability of terminators in genetic system design by using terminators as regulatory genetic parts. Terminators with different impacts on their upstream and downstream genes are characterized in detail via dynamic modeling to predict the behavior of the overall genetic system. Some nonlinear effects of terminators observed in our terminator measurements potentially facilitate regulation of gene expression. Through dynamic modeling in silico, we find that such genetic systems may behave like genetic filters. In agreement with the simulations, we successfully implement genetic high-pass and bandpass filters in vivo, demonstrating the potential of using terminators as regulatory parts. The genetic bandpass filter in this work is implemented through the interdependence between genetic parts, in which the termination efficiency of a terminator varies with the strength of the upstream promoter. This design strategy for a bandpass filter requires fewer base pairs than the conventional strategy of concatenating high-pass and low-pass filters. Our results show that this novel utilization of terminators as regulatory parts may provide a new perspective for efficient design of genetic circuits. We believe that further exploration of the complicated dynamics of terminators is important in the development of synthetic biology. PMID:26912179

  18. Development of a Korotkov sound processor for automatic identification of auscultatory events. I - Specification of preprocessing bandpass filters

    NASA Technical Reports Server (NTRS)

    Golden, D. P., Jr.; Wolthuis, R. A.; Hoffler, G. W.; Gowen, R. J.

    1974-01-01

    Frequency bands that best discriminate the Korotkov sounds at systole and at diastole from the sounds immediately preceding these events are defined. Korotkov sound data were recorded from five normotensive subjects during orthostatic stress (lower body negative pressure) and bicycle ergometry. A spectral analysis of the seven Korotkov sounds centered about the systolic and diastolic auscultatory events revealed that a maximum increase in amplitude at the systolic transition occurred in the 18-26-Hz band, while a maximum decrease in amplitude at the diastolic transition occurred in the 40-60-Hz band. These findings were remarkably consistent across subjects and test conditions. These passbands are included in the design specifications for an automatic blood pressure measuring system used in conjuction with medical experiments during NASA's Skylab program.

  19. Quantitative Determination of Bandpasses for Producing Vegetation Indices from Recombined NEON Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Hulslander, D.

    2015-12-01

    Hyperspectral imaging systems can be used to produce spectral reflectance curves giving rich information about composition, relative abundances of materials, mixes and combinations. However, as each spectral return from these systems is a vector with several hundred elements, they can be very difficult to process and analyze, and problemeatic to compare within, across, and between datasets over time and space. Vegetation indices (e.g. NDVI, ARVI, EVI, et al) attempt to combine spectral features in to single-value scores. When derived from calibrated and atmospherically compensated reflectance data, these indices can be quantitatively compared. Historically, these indices have been calculated from multispectral sensor data. These sensors have a handful (4 to 16 or so) of bandbasses ranging from 20 nm to 200 nm FWHM covering specific spectral regions for a variety of reasons, including both intended applications and system limitations. Hyperspectral sensors, however, cover the spectrum with many, many narrow (5 to 10 nm) bandpasses. This allows for analyses using the full, detailed spectral curve, or combination of the bands in to regions by averaging or in to composites using transforms or other techniques. This raises the question of exactly which bands should be used and combined in what manner for ideally deriving well-known vegetation indices typically made from multispectral data. In this study we use derivatives and other curve and signal analysis techniques to analyze vegetation reflectance spectra to quantitatively define optimal bandpasses for several vegetation indices and combine the 5 nm hypserspectral bandpasses of the NEON Imaging Spectrometer to synthesize them.

  20. Filtering apparatus

    DOEpatents

    Haldipur, Gaurang B.; Dilmore, William J.

    1992-01-01

    A vertical vessel having a lower inlet and an upper outlet enclosure separated by a main horizontal tube sheet. The inlet enclosure receives the flue gas from a boiler of a power system and the outlet enclosure supplies cleaned gas to the turbines. The inlet enclosure contains a plurality of particulate-removing clusters, each having a plurality of filter units. Each filter unit includes a filter clean-gas chamber defined by a plate and a perforated auxiliary tube sheet with filter tubes suspended from each tube sheet and a tube connected to each chamber for passing cleaned gas to the outlet enclosure. The clusters are suspended from the main tube sheet with their filter units extending vertically and the filter tubes passing through the tube sheet and opening in the outlet enclosure. The flue gas is circulated about the outside surfaces of the filter tubes and the particulate is absorbed in the pores of the filter tubes. Pulses to clean the filter tubes are passed through their inner holes through tubes free of bends which are aligned with the tubes that pass the clean gas.

  1. Filtering apparatus

    DOEpatents

    Haldipur, G.B.; Dilmore, W.J.

    1992-09-01

    A vertical vessel is described having a lower inlet and an upper outlet enclosure separated by a main horizontal tube sheet. The inlet enclosure receives the flue gas from a boiler of a power system and the outlet enclosure supplies cleaned gas to the turbines. The inlet enclosure contains a plurality of particulate-removing clusters, each having a plurality of filter units. Each filter unit includes a filter clean-gas chamber defined by a plate and a perforated auxiliary tube sheet with filter tubes suspended from each tube sheet and a tube connected to each chamber for passing cleaned gas to the outlet enclosure. The clusters are suspended from the main tube sheet with their filter units extending vertically and the filter tubes passing through the tube sheet and opening in the outlet enclosure. The flue gas is circulated about the outside surfaces of the filter tubes and the particulate is absorbed in the pores of the filter tubes. Pulses to clean the filter tubes are passed through their inner holes through tubes free of bends which are aligned with the tubes that pass the clean gas. 18 figs.

  2. The J-PAS filter system

    NASA Astrophysics Data System (ADS)

    Marin-Franch, Antonio; Taylor, Keith; Cenarro, Javier; Cristobal-Hornillos, David; Moles, Mariano

    2015-08-01

    J-PAS (Javalambre-PAU Astrophysical Survey) is a Spanish-Brazilian collaboration to conduct a narrow-band photometric survey of 8500 square degrees of northern sky using an innovative filter system of 59 filters, 56 relatively narrow-band (FWHM=14.5 nm) filters continuously populating the spectrum between 350 to 1000nm in 10nm steps, plus 3 broad-band filters. This filter system will be able to produce photometric redshifts with a precision of 0.003(1 + z) for Luminous Red Galaxies, allowing J-PAS to measure the radial scale of the Baryonic Acoustic Oscillations. The J-PAS survey will be carried out using JPCam, a 14-CCD mosaic camera using the new e2v 9k-by-9k, 10μm pixel, CCDs mounted on the JST/T250, a dedicated 2.55m wide-field telescope at the Observatorio Astrofísico de Javalambre (OAJ) near Teruel, Spain. The filters will operate in a fast (f/3.6) converging beam. The requirements for average transmissions greater than 85% in the passband, <10-5 blocking from 250 to 1050nm, steep bandpass edges and high image quality impose significant challenges for the production of the J-PAS filters that have demanded the development of new design solutions. This talk presents the J-PAS filter system and describes the most challenging requirements and adopted design strategies. Measurements and tests of the first manufactured filters are also presented.

  3. Design of doubly focusing, tunable (5 to 30 keV), wide-bandpass optics made from layered synthetic microstructures

    SciTech Connect

    Bilderback, D.H.; Lairson, B.M.; Barbee, T.W. Jr.; Ice, G.E.; Sparks, C.J. Jr.

    1982-01-01

    Layered Synthetic Microstructures (LSMs) show great promise as focusing, high-throughput, hard x-ray monochromators. Experimental reflectivity vs. energy curves have been obtained on carbon-tungsten and carbon-molybdenum LSMs of up to 260 layers in thickness. Reflectivities for three flat LSMs with different bandpasses were 70% with ..delta..E/E = 5.4%, 66% with ..delta..E/E = 1.4%, and 19% with ..delta..E/E = 0.6%. A new generation of variable bandwidth optics using two successive LSMs is proposed. The first element will be an LSM deposited on a substrate that can be water cooled as it intercepts direct radiation from a storage ring. It can be bent for vertical focusing. The bandpass can be adjusted by choosing interchangeable first elements from an assortment of LSM's with different bandpasses (for example, ..delta..E/E = 0.005, 0.01, 0.02, 0.05, 0.1). The second LSM will consist of a multilayered structure with a 10% bandpass built onto a flexible substrate that can be bent for sagittal focusing. The result will be double focusing optics with an adjustable energy bandpass that are tunable from 5 to 30 keV.

  4. A matched filter algorithm for acoustic signal detection

    NASA Astrophysics Data System (ADS)

    Jordan, D. W.

    1985-06-01

    This thesis is a presentation of several alternative acoustic filter designs which allow Space Shuttle payload experiment initiation prior to launch. This initiation is accomplished independently of any spacecraft services by means of a matched band-pass filter tuned to the acoustic signal characteristic of the Auxiliary Power Unit (APU) which is brought up to operating RPM's approximately five minutes prior to launch. These alternative designs include an analog filter built around operational amplifiers, a digital IIR design implemented with an INTEL 2920 Signal Processor, and an Adaptive FIR Weiner design. Working prototypes of the first two filters are developed and a discussion of the advantage of the 2920 digital design is presented.

  5. New class of filter functions generated most directly by Christoffel-Darboux formula for Gegenbauer orthogonal polynomials

    NASA Astrophysics Data System (ADS)

    Ilić, Aleksandar D.; Pavlović, Vlastimir D.

    2011-01-01

    A new original formulation of all pole low-pass filter functions is proposed in this article. The starting point in solving the approximation problem is a direct application of the Christoffel-Darboux formula for the set of orthogonal polynomials, including Gegenbauer orthogonal polynomials in the finite interval [-1, +1] with the application of a weighting function with a single free parameter. A general solution for the filter functions is obtained in a compact explicit form, which is shown to enable generation of the Gegenbauer filter functions in a simple way by choosing the value of the free parameter. Moreover, the proposed solution with the same criterion of approximation could be used to generate Legendre and Chebyshev filter functions of the first and second kind as well. The examples of proposed filter functions of even (10th) and odd (11th) order are illustrated. The approximation is shown to yield a good compromise solution with respect to the filter frequency characteristics (magnitude as well as phase characteristics). The influence of tolerance of the filter critical component (inductor) on the proposed magnitude and group delay characteristics of a resistively terminated LC lossless ladder filter is analysed as well. The proposed filter functions are superior in terms of the excellent magnitude characteristic, which approximates an ideal filter almost perfectly over the entire pass-band range and exhibits the summed sensitivity function better than that of a Butterworth filter. In the article, we present the filter function solution that exhibits optimum amplitude as well as optimum group delay characteristics that are of crucial importance for implementation of digital processing as well as RF analogue parts of communication networks. Derivation of the other band range filter functions, which could be realised either by continuous or digital filters, is also generally possible with the procedure proposed in this article.

  6. Ultra-high peak rejection notch microwave photonic filter using a single silicon microring resonator.

    PubMed

    Long, Yun; Wang, Jian

    2015-07-13

    We propose a simple scheme to realize ultra-high peak rejection notch microwave photonic filter (MPF) based on a single silicon microring resonator (MRR). Using the combination of a conventional phase modulator (PM), a tunable bandpass filter (TBF), and a silicon MRR to manipulate the phase and amplitude of optical sidebands resulting in a signal cancellation at the RF notch filter frequency, we experimentally demonstrate a notch MPF with an ultra-high peak rejection beyond 60 dB. The frequency tunability of the proposed ultra-high peak rejection MPF is also demonstrated in the experiment. PMID:26191836

  7. High-efficiency microwave photonic harmonic down-conversion with tunable and reconfigurable filtering.

    PubMed

    Liao, Jinxin; Zheng, Xiaoping; Li, Shangyuan; Zhang, Hanyi; Zhou, Bingkun

    2014-12-01

    A new optical-frequency comb-based microwave photonic harmonic down-convertor with tunable and reconfigurable filtering is proposed and experimentally demonstrated. The coherent evenly spaced optical carriers offer harmonic down-conversion for ultrahigh radio frequency signals with low-frequency local oscillator, and construct a tunable and reconfigurable bandpass filter for the intermediate-frequency (IF) signal combined with dispersion. This implementation features high conversion efficiency. Experimental results show the filtered output IF signal has a clean spectrum with high quality. Measured conversion loss is 8.3 dB without extra electrical amplification. PMID:25490622

  8. Feature Identification and Filtering for Engine Misfire Detection (EMD) Using Zirconia Oxygen Sensor

    NASA Astrophysics Data System (ADS)

    Pauzi, Muhammad Zaim Mohamed; Abu Bakar, Elmi; Fauzi Ismail, Mohd

    2016-02-01

    Vehicles as transportation are popular and mainly use among peoples around the world for various kind of purpose either personal or not. Over hundreds of year internal combustion engines widely used because of high efficiency and low maintenance compare to new technology which are using cells of battery. Nevertheless, emission cause of incomplete combustion such engine misfire normally occurs as well. For instances, some mechanical, sensors or actuators failure and environmental condition contribute to the engine misfire. The importance of engine misfire detection (EMD) is to ensure engine emissions not harmful to the environments and avoid damage of catalytic converter. By using low cost narrowband oxygen sensor to acquire air to fuel ratio (AFR) signal behavior under misfire condition and analyst by digital signal processing method using Discrete Fourier Transform (DFT) algorithm for Digital Butterworth Filter designation is discussed in this paper.

  9. Selecting the optimal anti-aliasing filter for multichannel biosignal acquisition intended for inter-signal phase shift analysis.

    PubMed

    Keresnyei, Róbert; Megyeri, Péter; Zidarics, Zoltán; Hejjel, László

    2015-01-01

    The availability of microcomputer-based portable devices facilitates the high-volume multichannel biosignal acquisition and the analysis of their instantaneous oscillations and inter-signal temporal correlations. These new, non-invasively obtained parameters can have considerable prognostic or diagnostic roles. The present study investigates the inherent signal delay of the obligatory anti-aliasing filters. One cycle of each of the 8 electrocardiogram (ECG) and 4 photoplethysmogram signals from healthy volunteers or artificially synthesised series were passed through 100-80-60-40-20 Hz 2-4-6-8th order Bessel and Butterworth filters digitally synthesized by bilinear transformation, that resulted in a negligible error in signal delay compared to the mathematical model of the impulse- and step responses of the filters. The investigated filters have as diverse a signal delay as 2-46 ms depending on the filter parameters and the signal slew rate, which is difficult to predict in biological systems and thus difficult to compensate for. Its magnitude can be comparable to the examined phase shifts, deteriorating the accuracy of the measurement. As a conclusion, identical or very similar anti-aliasing filters with lower orders and higher corner frequencies, oversampling, and digital low pass filtering are recommended for biosignal acquisition intended for inter-signal phase shift analysis. PMID:25514627

  10. Demonstration and experimental evaluation of a bi-directional 10-GHz microwave photonic filter

    NASA Astrophysics Data System (ADS)

    Zaldívar-Huerta, I. E.; Correa-Mena, A. G.; Hernández-Nava, P.; García-Juárez, A.; Rodríguez-Asomoza, J.; Lee, Min Won

    2016-09-01

    A bi-directional 10-GHz microwave photonic filter is proposed and experimentally evaluated. Its frequency response consists of a series of microwave band-pass windows obtained by the interaction of externally modulated multimode laser diodes emitting around of 1550 nm associated to the chromatic dispersion parameter of an optical fiber, as well as the length of the optical link. Microwave band-pass windows exhibit on average a-3 dB bandwidth of 378 MHz. This electro-optical system shows an efficient configuration and good performance. Potentially, filtered microwave signals can be used as electrical carriers in optical communication systems to transmit and distribute services such as video, voice and data.

  11. Ultracompact ring resonator microwave photonic filters based on photonic crystal waveguides.

    PubMed

    Shen, Guansheng; Tian, Huiping; Ji, Yuefeng

    2013-02-20

    We design two microwave photonic filters (notch filter and bandpass filter) based on silicon on insulator (SOI) photonic crystal waveguides for a 60 GHz single-sideband signal radio-over-fiber (ROF) system. By perturbing the radii of the first two rows of holes adjacent to the photonic crystal waveguide, we obtained a broad negligible dispersion bandwidth and a corresponding constant low group velocity. With the slow light effect, the delay line of filters can be significantly reduced while providing the same delay time as fiber based delay lines. The simulation results show that the delay-line length of the notch filter is only about 25.9 μm, and it has a free spectral range of 130 GHz, a baseband width (BW) of 4.12 GHz, and a notch depth of 22 dB. The length of the bandpass filter is 62.4 μm, with a 19.6 dB extinction ratio and a 4.02 GHz BW, and the signal-to-noise ratio requirement of received data can be reduced by 9 dB for the 10(-7) bit-error ratio. Demonstrated microwave photonic crystal filters could be used in a future high-frequency millimeter ROF system. PMID:23434992

  12. Optimal filter design for shielded and unshielded ambient noise reduction in fetal magnetocardiography

    NASA Astrophysics Data System (ADS)

    Comani, S.; Mantini, D.; Alleva, G.; Di Luzio, S.; Romani, G. L.

    2005-12-01

    The greatest impediment to extracting high-quality fetal signals from fetal magnetocardiography (fMCG) is environmental magnetic noise, which may have peak-to-peak intensity comparable to fetal QRS amplitude. Being an unstructured Gaussian signal with large disturbances at specific frequencies, ambient field noise can be reduced with hardware-based approaches and/or with software algorithms that digitally filter magnetocardiographic recordings. At present, no systematic evaluation of filters' performances on shielded and unshielded fMCG is available. We designed high-pass and low-pass Chebychev II-type filters with zero-phase and stable impulse response; the most commonly used band-pass filters were implemented combining high-pass and low-pass filters. The achieved ambient noise reduction in shielded and unshielded recordings was quantified, and the corresponding signal-to-noise ratio (SNR) and signal-to-distortion ratio (SDR) of the retrieved fetal signals was evaluated. The study regarded 66 fMCG datasets at different gestational ages (22-37 weeks). Since the spectral structures of shielded and unshielded magnetic noise were very similar, we concluded that the same filter setting might be applied to both conditions. Band-pass filters (1.0-100 Hz) and (2.0-100 Hz) provided the best combinations of fetal signal detection rates, SNR and SDR; however, the former should be preferred in the case of arrhythmic fetuses, which might present spectral components below 2 Hz.

  13. Photonic crystal ring resonator based optical filters for photonic integrated circuits

    SciTech Connect

    Robinson, S.

    2014-10-15

    In this paper, a two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based optical Filters namely Add Drop Filter, Bandpass Filter, and Bandstop Filter are designed for Photonic Integrated Circuits (PICs). The normalized output response of the filters is obtained using 2D Finite Difference Time Domain (FDTD) method and the band diagram of periodic and non-periodic structure is attained by Plane Wave Expansion (PWE) method. The size of the device is minimized from a scale of few tens of millimeters to the order of micrometers. The overall size of the filters is around 11.4 μm × 11.4 μm which is highly suitable of photonic integrated circuits.

  14. Universal filters of arbitrary order and type employing square-root-domain technique

    NASA Astrophysics Data System (ADS)

    Khanday, F. A.; Psychalinos, C.; Shah, N. A.

    2014-07-01

    Novel Single Input Multiple Output (SIMO) and Multiple Input Single Output (MISO) universal filter topologies of arbitrary order and type are introduced in this paper. The proposed topologies have been realised by employing Square-Root Domain (SRD) technique. An offered benefit of the universal filter topologies is that only grounded capacitors are required for their implementations and the resonant frequency of the filters can be electronically controlled by an appropriate dc current. The proposed universal filters simultaneously offer all the five standard filtering functions i.e. Lowpass (LP), Highpass (HP) and Bandpass (BP), Bandstop (BS) and Allpass (AP) frequency responses. In addition, the SIMO topology is generic in the sense that it can yield four different stable filter configurations. Two design examples are provided in each configuration and the correct operation of the corresponding topologies has been evaluated through the PSPICE software with BSIM 0.35-µm CMOS process model parameters.

  15. National Seismic Stations transducers and filters

    SciTech Connect

    Rodgers, P.W.; Hummell, M.

    1981-01-13

    The National Seismic Stations (NSS) instruments are being developed for seismic monitoring of regional and teleseismic events. They consist of two 3-component, broadband, borehole seismometers: the KS-36000 and the S-700, which is the backup for the KS-36000. Output is divided into frequency bands to reduce data loss due to saturation. Complete block diagrams of the KS-36000 and S-700 NSS seismometers and filters are presented. Both open-loop and closed-loop steady-state amplitude and phase curves are given. Without band-pass filters (but with shaping filters) the KS-36000 has a flat (i.e., between the -3dB points) velocity sensitivity from 0.03 to 23 Hz. With its shaping filters, the S-700 is flat from 0.2 to 40 Hz. The structure of the three band-pass filters (LP, MP, and SP) is superimposed on these velocity sensitivities. Passbands of the resulting overall velocity sensitivity for the KS-36000 are as follows: LP band = 0.01-0.05 Hz, MP band = 0.02-1.3 Hz, and SP band = 1-10 Hz. Step-function responses and phase and group delays are given for each of the bands. The MP-band step response is oscillatory due to its sharp, high-frequency cutoff, but an MP-band filter with a less abrupt cutoff eliminates the oscillation. To generate typical NSS output seismograms, velocity inputs from four representative seismic events were used: an underground nuclear test (..delta.. approx. = 3.6/sup 0/), a regional earthquake (..delta.. approx. = 20/sup 0/), a local earthquake (..delta.. approx. = 1.5/sup 0/), and a teleseismic earthquake (..delta.. approx. = 123/sup 0/). The velocity inputs for these events were obtained from the LLNL digital seismic network (DSS) around the Nevada Test Site (NTS). The seismograms resulting from each of the bands were satisfactory, although the low-frequency corner of the MP band should be increased in frequency to 0.08 Hz.

  16. A simple tuning method for high temperature superconducting microstrip filters

    NASA Astrophysics Data System (ADS)

    Pal, Srikanta; Stevens, Chris; Edwards, David

    2005-07-01

    In this paper we report a simple tuning methodology of high temperature superconducting (HTS) microstrip filters. In order to establish this new tuning approach a 5 pole lumped element HTS bandpass filter, centre frequency 800 MHz, narrowband (bandwidth, 7.6 MHz), is designed and fabricated on a 2 inch (diameter) Y Ba2Cu3O6.94 thin film of thickness 700 nm and lanthanum aluminate (LaAlO3) substrate of 0.5 mm thickness. The filter was etched using conventional photolithography and a wet chemical etching process. The 5 pole lumped element filter is tested in an integrated RF-cryocooler measurement system at 65 K and also in liquid nitrogen (77 K). We demonstrate a 19.3 MHz downward shift of the centre frequency of the 5 pole filter response. This is achieved by overlaying two layers of thin dielectric tape (PTFE) (50.0 µm thickness, permittivity 3.2) over the conducting patterned part of the filter surface. A full wave electromagnetic analysis of the dielectric environment of this tuning arrangement matches the measured response closely. To improve the passband response, the filter is tuned in liquid nitrogen, placing pieces of sapphire rods over the resonators of the filter layout.

  17. The effects of sinusoidal interference on the second-order carrier tracking loop preceded by a bandpass limiter in the Block 4 receiver

    NASA Technical Reports Server (NTRS)

    Ruggier, C. J.

    1989-01-01

    Drop-lock relationships for the second-order phase-locked loop are derived when the carrier and a sinusoidal signal lie within the predetection filter bandwidth of the Block 4 receiver. Limiter suppression factors are calculated when a bandpass hard limiter is used to maintain constant total power at the loop. The parameters of interest are the interference-to-signal power ratio (ISR), the input signal-to-noise power ratio (NSR), and the interference signal frequency offset from carrier delta f. Limiter suppression caused by the combined effects of the noise and the interference signal accounts for the variability in the drop-lock threshold for given values of the input SNR and ISR parameters. Going beyond earlier published work that focused on the limiter's effect on the drop-lock threshold; an account is made for the limiter action in the interference mode and an overall imporvement is provided in the prediction accuracy of the drop-lock model.

  18. A Fast Terahertz Spectrometer Based on Frequency Selective Surface Filters

    NASA Astrophysics Data System (ADS)

    Carelli, P.; Chiarello, F.; Cibella, S.; Di Gaspare, A.; Leoni, R.; Ortolani, M.; Torrioli, G.

    2012-05-01

    We present a fast spectrometer working in the 0.7-4.8 THz range. Broadband radiation from a blackbody source is focused first on a rotating silicon wafer, whose surface was patterned with 18 metal band-pass filters, then on the sample under test and finally is detected by a superconducting microbolometer with microsecond time constant. The bolometer sensor is coupled to a spiral antenna whose frequency band matches the spectral range of the filters. The spectral resolution is set by the filters quality factor of about 3. A dynamic range of 100 and a S/N ratio of 20 are achieved by integrating for less than 10 second. The detector can operate up to 6 K in a closed-cycle cooler, hence making the present apparatus suitable for building up a simple terahertz video-rate spectrometer.

  19. Mode-coupling mechanisms of resonant transmission filters.

    PubMed

    Niraula, Manoj; Yoon, Jae Woong; Magnusson, Robert

    2014-10-20

    We study theoretically modal properties and parametric dependence of guided-mode resonance bandpass filters operating in the mid- and near-infrared spectral domains. We investigate three different device architectures consisting of single, double, and triple layers based on all-transparent dielectric and semiconductor thin films. The three device classes show high-performance bandpass filter profiles with broad, flat low-transmission sidebands accommodating sharp transmission peaks with their efficiencies approaching 100% with appropriate blending of multiple guided modes. We present three modal coupling configurations forming complex mixtures of two or three distinct leaky modes coupling at different evanescent diffraction orders. These modal compositions produce various widths of sidebands ranging from ~30 nm to ~2100 nm and transmission peak-linewidths ranging from ~1 pm to ~10 nm. Our modal analysis demonstrates key attributes of subwavelength periodic thin-film structures in multiple-modal blending to achieve desired transmission spectra. The design principle is applicable to various optical elements such as high-power optical filters, low-noise label-free biochemical sensor templates, and high-density display pixels. PMID:25401615

  20. Optimization of the filter parameters in (99m)Tc myocardial perfusion SPECT studies: the formulation of flowchart.

    PubMed

    Shibutani, Takayuki; Onoguchi, Masahisa; Yamada, Tomoki; Kamida, Hiroki; Kunishita, Kohei; Hayashi, Yuuki; Nakajima, Tadashi; Kinuya, Seigo

    2016-06-01

    Myocardial perfusion single photon emission computed tomography (SPECT) is typically subject to a variation in image quality due to the use of different acquisition protocols, image reconstruction parameters and image display settings by each institution. One of the principal image reconstruction parameters is the Butterworth filter cut-off frequency, a parameter strongly affecting the quality of myocardial images. The objective of this study was to formulate a flowchart for the determination of the optimal parameters of the Butterworth filter for filtered back projection (FBP), ordered subset expectation maximization (OSEM) and collimator-detector response compensation OSEM (CDR-OSEM) methods using the evaluation system of the myocardial image based on technical grounds phantom. SPECT studies were acquired for seven simulated defects where the average counts of the normal myocardial components of 45° left anterior oblique projections were approximately 10-120 counts/pixel. These SPECT images were then reconstructed by FBP, OSEM and CDR-OSEM methods. Visual and quantitative assessment of short axis images were performed for the defect and normal parts. Finally, we formulated a flowchart indicating the optimal image processing procedure for SPECT images. Correlation between normal myocardial counts and the optimal cut-off frequency could be represented as a regression expression, which had high or medium coefficient of determination. We formulated the flowchart in order to optimize the image reconstruction parameters based on a comprehensive assessment, which enabled us to perform objectively processing. Furthermore, the usefulness of image reconstruction using the flowchart was demonstrated by a clinical case. PMID:27052439

  1. Characterization of geothermally relevant structures at the top of crystalline basement in Switzerland by filters and gravity forward modelling

    NASA Astrophysics Data System (ADS)

    Abdelfettah, Yassine; Schill, Eva; Kuhn, Pascal

    2014-10-01

    Some of the major geothermal anomalies in central Europe are linked to tectonic structures within the top of crystalline basement, which modify strongly the top of this basement. Their assessment is a major challenge in exploration geophysics. Gravity has been proven to be suitable for the detection of mainly large scale lithological and structural inhomogeneities. Indeed, it is well known and proven by different wells that, for example, in northern Switzerland extended negative anomalies are linked to such structures. Due to depth limitation of wells, there vertical extension is often unknown. In this study, we have investigated the potential of gravity for the geometrical characterization of such basement structures. Our approach consists in the combination of the series of Butterworth filters, geological modelling and best-fitting between observed and computed residual anomalies. In this respect, filters of variable wavelength are applied to observed and computed gravity data. The geological model is discretized into a finite element mesh. Near-surface anomalies and the effect of the sedimentary cover were eliminated using cut-off wavelength of 10 km and geological and seismic information. We analysed the potential of preferential Butterworth filtering in a sensitivity study and applied the above mentioned approach to part of the Swiss molasses basin. Sensitivity analyses reveal that such sets of residual anomalies represents a pseudo-tomography revealing the distribution of different structures with depth. This finding allows for interpreting negative anomalies in terms of 3-D volumes. Best-fitting then permits determination of the most likely 3-D geometries of such basement structures. Our model fits both, geological observations and gravity: among 10 deep boreholes in the studied area, six reach the respective units and confirm our distribution of the negative (and positive) anomalies.

  2. Water Filters

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Seeking to find a more effective method of filtering potable water that was highly contaminated, Mike Pedersen, founder of Western Water International, learned that NASA had conducted extensive research in methods of purifying water on board manned spacecraft. The key is Aquaspace Compound, a proprietary WWI formula that scientifically blends various types of glandular activated charcoal with other active and inert ingredients. Aquaspace systems remove some substances; chlorine, by atomic adsorption, other types of organic chemicals by mechanical filtration and still others by catalytic reaction. Aquaspace filters are finding wide acceptance in industrial, commercial, residential and recreational applications in the U.S. and abroad.

  3. Potential-controlled filtering in quantum star graphs

    SciTech Connect

    Turek, Ondrej Cheon, Taksu

    2013-03-15

    We study the scattering in a quantum star graph with a Fueloep-Tsutsui coupling in its vertex and with external potentials on the lines. We find certain special couplings for which the probability of the transmission between two given lines of the graph is strongly influenced by the potential applied on another line. On the basis of this phenomenon we design a tunable quantum band-pass spectral filter. The transmission from the input to the output line is governed by a potential added on the controlling line. The strength of the potential directly determines the passband position, which allows to control the filter in a macroscopic manner. Generalization of this concept to quantum devices with multiple controlling lines proves possible. It enables the construction of spectral filters with more controllable parameters or with more operation modes. In particular, we design a band-pass filter with independently adjustable multiple passbands. We also address the problem of the physical realization of Fueloep-Tsutsui couplings and demonstrate that the couplings needed for the construction of the proposed quantum devices can be approximated by simple graphs carrying only {delta} potentials. - Highlights: Black-Right-Pointing-Pointer Spectral filtering devices based on quantum graphs are designed theoretically. Black-Right-Pointing-Pointer The passband is controlled by the application of macroscopic potentials on lines. Black-Right-Pointing-Pointer The filters are built upon special Fulop-Tsutsui type couplings at graph vertices. Black-Right-Pointing-Pointer A method of construction of Fulop-Tsutsui vertices from delta potentials is devised.

  4. DKIST visible broadband imager interference filters

    NASA Astrophysics Data System (ADS)

    Wöger, Friedrich

    2014-08-01

    The Visible Broadband Imager (VBI) is one of several first-light instruments of the Daniel K. Inouye Solar Telescope (DKIST, formerly known as the Advanced Technology Solar Telescope (ATST)). Operating at discrete wavelengths within a range of 390-860 nm, the VBI will be capable of sampling the solar atmosphere in several layers at the diffraction limit of DKIST's 4 meter aperture. The layers are selected by the peak wavelength and bandpass width of its interference filters that have to be manufactured to very tight specifications. We present the results of testing performed at the National Solar Observatory's Dunn Solar Telescope (DST) to confirm that the requirements were met by the vendor.

  5. An OTA-C filter for ECG acquisition systems with highly linear range and less passband attenuation

    NASA Astrophysics Data System (ADS)

    Jihai, Duan; Chuang, Lan; Weilin, Xu; Baolin, Wei

    2015-05-01

    A fifth order operational transconductance amplifier-C (OTA-C) Butterworth type low-pass filter with highly linear range and less passband attenuation is presented for wearable bio-telemetry monitoring applications in a UWB wireless body area network. The source degeneration structure applied in typical small transconductance circuit is improved to provide a highly linear range for the OTA-C filter. Moreover, to reduce the passband attenuation of the filter, a cascode structure is employed as the output stage of the OTA. The OTA-based circuit is operated in weak inversion due to strict power limitation in the biomedical chip. The filter is fabricated in a SMIC 0.18-μm CMOS process. The measured results for the filter have shown a passband gain of -6.2 dB, while the -3-dB frequency is around 276 Hz. For the 0.8 VPP sinusoidal input at 100 Hz, a total harmonic distortion (THD) of -56.8 dB is obtained. An electrocardiogram signal with noise interference is fed into this chip to validate the function of the designed filter. Project supported by the National Natural Science Foundation of China (Nos. 61161003, 61264001, 61166004) and the Guangxi Natural Science Foundation (No. 2013GXNSFAA019333).

  6. Clutter filtering influence on blood velocity estimation using speckle tracking.

    PubMed

    Fadnes, Solveig; Bjærum, Steinar; Torp, Hans; Lovstakken, Lasse

    2015-12-01

    Blood speckle tracking has shown potential for solving the angle-dependency limitation in color flow imaging. However, as clutter filtering is still Doppler-based, flow velocities at near-perpendicular beam-to-flow angles can be severely attenuated. It is shown that the clutter filter also alters the speckle appearance through a decrease in the lateral imaging bandwidth, leading to poorer lateral resolution and thus tracking performance. Interestingly, at perpendicular beam-to-flow angles lateral band-pass characteristics are inferred, and the resulting lateral amplitude modulation could help improve tracking estimates. Simulations and flow phantom experiments showed that substantially improved results could be achieved by utilizing time-variant clutter filters (e.g., polynomial regression filters) despite the inherent decorrelation inferred by these filters, but only for higher ensemble sizes (N > 36). We found that, compared with color flow imaging, speckle tracking could yield consistent estimates well below the clutter filter cutoff, but with a higher variance attributed to the low signalto- noise ratio inferred by filter attenuation. Overall, provided that a low f-number and high ensemble lengths (N approx. > 36) can be used, speckle tracking can consistently provide angle- independent flow velocity estimates, limited only by a lower bound on the flow velocity itself. PMID:26670849

  7. First Light of the Near-Infrared Narrow-Band Tunable Birefringent Filter at Big Bear Solar Observatory

    NASA Astrophysics Data System (ADS)

    Cao, Wenda; Hartkorn, Klaus; Ma, Jun; Xu, Yan; Spirock, Tom; Wang, Haimin; Goode, Philip R.

    2006-10-01

    We discuss a near-infrared (NIR) narrow-band tunable birefringent filter system newly developed by the Big Bear Solar Observatory (BBSO). This is one of the first narrow-bandpass NIR filter systems working at 1.56 μm which is used for the observation of the deepest solar photosphere. Four stages of calcite were used to obtain a bandpass of 2.5 Å along with a free spectral range (FSR) of 40 Å. Some unique techniques were implemented in the design, including liquid crystal variable retarders (LCVRs) to tune the bandpass in a range of ±100 Å, a wide field configuration to provide up to 2° incident angle, and oil-free structure to make it more compact and handy. After performing calibration and characteristic evaluation at the Evans Facility of the National Solar Observatory at Sacramento Peak (NSO/SP), a series of high-resolution filtergrams and imaging polarimetry observations were carried out with the Dunn Solar Telescope of NSO/SP and the 65-cm telescope of BBSO, in conjunction with the high-order adaptive optics system and the Fabry-Pérot Interferometer (FPI). In this paper, we describe the optical design and discuss the calibration method. Preliminary observations show that it is capable of serving as either a stand-alone narrow-band filter for NIR filtergram observations or an order-sorting filter of a FPI applied to NIR two-dimensional imaging spectro-polarimetry.

  8. FILTER-INDUCED BIAS IN Lyα EMITTER SURVEYS: A COMPARISON BETWEEN STANDARD AND TUNABLE FILTERS. GRAN TELESCOPIO CANARIAS PRELIMINARY RESULTS

    SciTech Connect

    De Diego, J. A.; De Leo, M. A.; Cepa, J.; Bongiovanni, A.; Verdugo, T.; Sánchez-Portal, M.

    2013-10-01

    Lyα emitter (LAE) surveys have successfully used the excess in a narrowband filter compared to a nearby broadband image to find candidates. However, the odd spectral energy distribution (SED) of LAEs combined with the instrumental profile has important effects on the properties of the candidate samples extracted from these surveys. We investigate the effect of the bandpass width and the transmission profile of the narrowband filters used for extracting LAE candidates at redshifts z ≅ 6.5 through Monte Carlo simulations, and we present pilot observations to test the performance of tunable filters to find LAEs and other emission-line candidates. We compare the samples obtained using a narrow ideal rectangular filter, the Subaru NB921 narrowband filter, and sweeping across a wavelength range using the ultra-narrow-band tunable filters of the instrument OSIRIS, installed at the 10.4 m Gran Telescopio Canarias. We use this instrument for extracting LAE candidates from a small set of real observations. Broadband data from the Subaru, Hubble Space Telescope, and Spitzer databases were used for fitting SEDs to calculate photometric redshifts and to identify interlopers. Narrowband surveys are very efficient in finding LAEs in large sky areas, but the samples obtained are not evenly distributed in redshift along the filter bandpass, and the number of LAEs with equivalent widths <60 Å can be underestimated. These biased results do not appear in samples obtained using ultra-narrow-band tunable filters. However, the field size of tunable filters is restricted because of the variation of the effective wavelength across the image. Thus, narrowband and ultra-narrow-band surveys are complementary strategies to investigate high-redshift LAEs.

  9. Plasmonic filter array for on-chip near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Erwen; Chong, Xinyuan; Ren, Fanghui; Wang, Alan X.

    2016-03-01

    We demonstrate an ultra-compact on-chip spectrometer for near-infrared (NIR) spectroscopy based on narrow-band band-pass filter array. Each individual filter consists of a plasmonic metallic grating with subwavelength period and extremely narrow slits on a quartz substrate, with a polymer cover layer as the waveguide layer. A narrow-band guided-mode resonance (GMR) associated with a surface-plasmon resonance (SPR) gives rise to the narrow-band transmission spectrum. Full width at half maximum (FWHM) of fabricated filter's spectrum is measured to be from 7 to 13 nm, and the operation bandwidth of the entire filter array covers wavelength range over 270 nm from 1510 to 1780 nm. We measure the NIR absorbance spectrum of xylene using our filter array device to demonstrate its application as a spectrometer.

  10. Water Filter

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A compact, lightweight electrolytic water sterilizer available through Ambassador Marketing, generates silver ions in concentrations of 50 to 100 parts per billion in water flow system. The silver ions serve as an effective bactericide/deodorizer. Tap water passes through filtering element of silver that has been chemically plated onto activated carbon. The silver inhibits bacterial growth and the activated carbon removes objectionable tastes and odors caused by addition of chlorine and other chemicals in municipal water supply. The three models available are a kitchen unit, a "Tourister" unit for portable use while traveling and a refrigerator unit that attaches to the ice cube water line. A filter will treat 5,000 to 10,000 gallons of water.

  11. Optimal bandpass sampling strategies for enhancing the performance of a phase noise meter

    NASA Astrophysics Data System (ADS)

    Angrisani, Leopoldo; Schiano Lo Moriello, Rosario; D'Arco, Mauro; Greenhall, Charles

    2008-10-01

    Measurement of phase noise affecting oscillators or clocks is a fundamental practice whenever the need of a reliable time base is of primary concern. In spite of the number of methods or techniques either available in the literature or implemented as personalities in general-purpose equipment, very accurate measurement results can be gained only through expensive, dedicated instruments. To offer a cost-effective alternative, the authors have already realized a DSP-based phase noise meter, capable of assuring good performance and real-time operation. The meter, however, suffers from a reduced frequency range (about 250 kHz), and needs an external time base for input signal digitization. To overcome these drawbacks, the authors propose the use of bandpass sampling strategies to enlarge the frequency range, and of an internal time base to make standalone operation much more feasible. After some remarks on the previous version of the meter, key features of the adopted time base and proposed sampling strategies are described in detail. Results of experimental tests, carried out on sinusoidal signals provided both by function and arbitrary waveform generators, are presented and discussed; evidence of the meter's reliability and efficacy is finally given.

  12. The effects of bandpass limiters on n-phase tracking systems

    NASA Technical Reports Server (NTRS)

    Butman, S. A.; Lesh, J. R.

    1977-01-01

    The combination of a bandpass limiter and an n(th) power tracking loop is considered. It is shown that the performance of the combination does not depend on the form of the nonlinear function used to create the n(th) harmonic signal so long as some energy in that zone is produced. Furthermore, the order in which the limiter and n(th) power nonlinearity occur is unimportant so that the results apply equally well to the n-phase Costas type of implementation of the n(th) power loops. Closed form expressions for the signal suppression factors are obtained and it is shown that the coherent and noncoherent SNR's out of the n(th) power-limiter combination can be expressed in terms of two of these suppression factors. This later point enables one to estimate the loop SNR of an n(th) power-limiter phase locked loop by simply calculating the suppression factors for n(th) and 2n(th) power loops. Finally, n(th) power phase locked loops without limiters are compared with similar loops with limiters where it is shown that the presence of the limiter can actually enhance the output SNR at moderate to large values of input SNR.

  13. The effects of bandpass limiters on n-phase tracking systems

    NASA Technical Reports Server (NTRS)

    Butman, S. A.; Lesh, J. R.

    1977-01-01

    The combination of a bandpass limiter and an n-th power tracking loop is considered. Performance of the combination does not depend on the form of the nonlinear function used to create the n-th harmonic signal as long as some energy in that zone is produced. The order in which the limiter and n-th power nonlinearity occur is unimportant so that the results apply equally well to the n-phase Costas type of implementations of the n-th power loops. Closed form expressions for the signal suppression factors are obtained. Coherent and noncoherent SNR's out of the n-th power-limiter combination can be expressed in terms of two of these suppression factors. The loop SNR of an n-th power-limited phase locked loop is estimated by simply calculating the suppression factors for n-th and 2n-th power loops. Finally, n-th power phase locked loops without limiters are compared with similar loops with limiters; the limiter can actually enhance output SNR at moderate to large input SNR.

  14. Eyeglass Filters

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Biomedical Optical Company of America's suntiger lenses eliminate more than 99% of harmful light wavelengths. NASA derived lenses make scenes more vivid in color and also increase the wearer's visual acuity. Distant objects, even on hazy days, appear crisp and clear; mountains seem closer, glare is greatly reduced, clouds stand out. Daytime use protects the retina from bleaching in bright light, thus improving night vision. Filtering helps prevent a variety of eye disorders, in particular cataracts and age related macular degeneration.

  15. Substrate Integrated Waveguide Cross-Coupling Filter with Multilayer Hexagonal Cavity

    PubMed Central

    Wu, B.; Xu, Z. Q.; Liao, J. X.

    2013-01-01

    Hexagonal cavities and their applications to multilayer substrate integrated waveguide (SIW) filters are presented. The hexagonal SIW cavity which can combine flexibility of rectangular one and performance of circular one is convenient for bandpass filter's design. Three types of experimental configuration with the same central frequency of 10 GHz and bandwidth of 6%, including three-order and four-order cross-coupling topologies, are constructed and fabricated based on low temperature cofired ceramic (LTCC) technology. Both theoretical and experimental results are presented. PMID:24459441

  16. Substrate integrated waveguide cross-coupling filter with multilayer hexagonal cavity.

    PubMed

    Wu, B; Xu, Z Q; Liao, J X

    2013-01-01

    Hexagonal cavities and their applications to multilayer substrate integrated waveguide (SIW) filters are presented. The hexagonal SIW cavity which can combine flexibility of rectangular one and performance of circular one is convenient for bandpass filter's design. Three types of experimental configuration with the same central frequency of 10 GHz and bandwidth of 6%, including three-order and four-order cross-coupling topologies, are constructed and fabricated based on low temperature cofired ceramic (LTCC) technology. Both theoretical and experimental results are presented. PMID:24459441

  17. Voltage-mode multifunction biquadratic filter with one input and six outputs using two ICCIIs.

    PubMed

    Chen, Hua-Pin

    2014-01-01

    A novel voltage-mode multifunction biquadratic filter with one input and six outputs is presented. The proposed circuit can realize inverting and noninverting low-pass, bandpass, and high-pass filters, simultaneously, by using two inverting second-generation current conveyors (ICCIIs), two grounded capacitors, and four resistors. Moreover, the proposed circuit offers the following attractive advantages: no requirements for component matching conditions, the use of only grounded capacitors, and low active and passive sensitivities. HSPICE and MATLAB simulations results are provided to demonstrate the theoretical analysis. PMID:24895651

  18. Voltage-Mode Multifunction Biquadratic Filter with One Input and Six Outputs Using Two ICCIIs

    PubMed Central

    Chen, Hua-Pin

    2014-01-01

    A novel voltage-mode multifunction biquadratic filter with one input and six outputs is presented. The proposed circuit can realize inverting and noninverting low-pass, bandpass, and high-pass filters, simultaneously, by using two inverting second-generation current conveyors (ICCIIs), two grounded capacitors, and four resistors. Moreover, the proposed circuit offers the following attractive advantages: no requirements for component matching conditions, the use of only grounded capacitors, and low active and passive sensitivities. HSPICE and MATLAB simulations results are provided to demonstrate the theoretical analysis. PMID:24895651

  19. Tunable Microwave Filter Design Using Thin-Film Ferroelectric Varactors

    NASA Astrophysics Data System (ADS)

    Haridasan, Vrinda

    Military, space, and consumer-based communication markets alike are moving towards multi-functional, multi-mode, and portable transceiver units. Ferroelectric-based tunable filter designs in RF front-ends are a relatively new area of research that provides a potential solution to support wideband and compact transceiver units. This work presents design methodologies developed to optimize a tunable filter design for system-level integration, and to improve the performance of a ferroelectric-based tunable bandpass filter. An investigative approach to find the origins of high insertion loss exhibited by these filters is also undertaken. A system-aware design guideline and figure of merit for ferroelectric-based tunable band- pass filters is developed. The guideline does not constrain the filter bandwidth as long as it falls within the range of the analog bandwidth of a system's analog to digital converter. A figure of merit (FOM) that optimizes filter design for a specific application is presented. It considers the worst-case filter performance parameters and a tuning sensitivity term that captures the relation between frequency tunability and the underlying material tunability. A non-tunable parasitic fringe capacitance associated with ferroelectric-based planar capacitors is confirmed by simulated and measured results. The fringe capacitance is an appreciable proportion of the tunable capacitance at frequencies of X-band and higher. As ferroelectric-based tunable capac- itors form tunable resonators in the filter design, a proportionally higher fringe capacitance reduces the capacitance tunability which in turn reduces the frequency tunability of the filter. Methods to reduce the fringe capacitance can thus increase frequency tunability or indirectly reduce the filter insertion-loss by trading off the increased tunability achieved to lower loss. A new two-pole tunable filter topology with high frequency tunability (> 30%), steep filter skirts, wide stopband

  20. Self-emission glucose monitoring system with single chip guided-mode resonance filters

    NASA Astrophysics Data System (ADS)

    Yeh, Yen-Chun; Yang, Sheng; Schmidt, Dominik

    2016-03-01

    In this study, we designed and simulated an array of bandpass filters as a spectral separator for mid-infrared self-emission noninvasive glucose monitoring, using the human body as the background radiation emitter. The filters were based on the guided-mode resonance (GMR) effect. The human body is a good black body radiator that provides a stable temperature and continuous radiation energy in the mid-infrared range. We can thus use self-emission from the human body to measure certain fingerprint peaks of glucose spectrum between 8 μm to 10 μm, which allows estimation of glucose concentration. The GMR filter set includes at least four filters on one chip fabricated at the same time. By using fixed thicknesses and the same thin-film material for all the filters on the chip, a structure period adjustment alone can theoretically achieve multiple bandpass filters between the glucose fingerprint ranges - and achieve these coplanar filters on a single chip. By using all CMOS-compatible materials, COMSOL simulations show that a series of peaks with transmittances up to 70% and bandwidths of around 200nm can be achieved. This filter set can be fabricated with just a few thin layers that can simplify the typical thin-film deposition process. The proposed GMR filter array can then be combined with a thermometer array to achieve the non-invasive glucose monitoring. We compare the results obtained with the first version of the fabricated filter set with the measurements of Fourier transform infrared (FT-IR) spectroscopy.

  1. Multi-GHz bandpass, high-repetition rate single channel mobile diagnostic system for ultra-wideband applications

    NASA Astrophysics Data System (ADS)

    Miner, Lynn M.; Voss, Donald E.

    1993-01-01

    Characterizing radiated ultra-wideband (UWB) signals poses challenges due to requirements for (1) multi-GHz bandpass recording of the signal's leading edge; (2) GHz-bandpass recording of long record lengths (10s-100s of ns); and (3) determining shot-to-shot reproducibility at rep-rates exceeding 10 kHz. The System Verification Apparatus (SVA) is a novel diagnostic system which can measure 60-ps rise-time signals on a single-shot basis, while monitoring pulse-to-pulse variation. The fully-integrated SVA includes a broadband sensor, signal and trigger conditioning electronics, multiple parallel digitizers with deep local storge, and automated software for acquiring, archiving, and analyzing waveform data with rapid (secs-minute) turnaround time. The instruments are housed in a portable 100-dB shielded aluminum enclosure. The SVA utilizes a 6-GHz bandpass free-field D-dot sensor to measure the incident electric field. Three separate digitizers together meet the requirements of high bandwidth, long record length, and high repetition rate. A 6-GHz bandpass scan converter digitizer captures the leading edge (few ns) of the radiated signal. 1-GHz and 600 MHz bandwidth solid-state digitizers supporting long record lengths (greater than 2 micrometers) record the balance of the signal, which typically contains negligible content above 1 GHz. These solid-state digitizers can store greater than 900 waveforms locally at rep-rates exceeding 65 Hz and 100 kHz, respectively. Data management and instrument control use an 80486-based PC, operating in a user-friendly Windows environment. All waveform and system configuration data are automatically stored in a built-in database. A fiber-optic link, up to 2 km long, provides electromagnetic isolation of the computer.

  2. Order-sorting filter transmittance measured with an array detector

    NASA Technical Reports Server (NTRS)

    Heaney, James B.; Bradley, Scott E.; Bly, Vincent T.; Ewin, Audrey J.; La, Anh T.

    1993-01-01

    The simultaneous measurement of the spectrally and spatially variant transmittance of a linear variable order-sorting filter in a manner that closely resembles its conditions of actual use is described. The transmittance of a prototype order-sorting filter was measured in the 400- to 880-nm wavelength region by illuminating it with the output beam of a spectrophotometer while the filter was attached to the front of a 30 x 32 pixel silicon array detector. The filter was designed to be used in the output beam of a grating spectrometer to prevent the dispersal of higher diffracted orders onto an array detector. Areas of the filter that were spatially matched to the corresponding detector pixel column had measured peak transmittances of about 90 percent that were uniform to within +/- 1.5 percent along a given column. Transmittances for incident wavelengths shorter than the desired bandpass, corresponding to the order overlap region, were measured in the 0.003 range. Line spread function measurements made with the array detector indicated no significant beam spreading caused by inserting the filter into the beam.

  3. Active Integrated Filters for RF-Photonic Channelizers

    PubMed Central

    Nagdi, Amr El; Liu, Ke; LaFave, Tim P.; Hunt, Louis R.; Ramakrishna, Viswanath; Dabkowski, Mieczyslaw; MacFarlane, Duncan L.; Christensen, Marc P.

    2011-01-01

    A theoretical study of RF-photonic channelizers using four architectures formed by active integrated filters with tunable gains is presented. The integrated filters are enabled by two- and four-port nano-photonic couplers (NPCs). Lossless and three individual manufacturing cases with high transmission, high reflection, and symmetric couplers are assumed in the work. NPCs behavior is dependent upon the phenomenon of frustrated total internal reflection. Experimentally, photonic channelizers are fabricated in one single semiconductor chip on multi-quantum well epitaxial InP wafers using conventional microelectronics processing techniques. A state space modeling approach is used to derive the transfer functions and analyze the stability of these filters. The ability of adapting using the gains is demonstrated. Our simulation results indicate that the characteristic bandpass and notch filter responses of each structure are the basis of channelizer architectures, and optical gain may be used to adjust filter parameters to obtain a desired frequency magnitude response, especially in the range of 1–5 GHz for the chip with a coupler separation of ∼9 mm. Preliminarily, the measurement of spectral response shows enhancement of quality factor by using higher optical gains. The present compact active filters on an InP-based integrated photonic circuit hold the potential for a variety of channelizer applications. Compared to a pure RF channelizer, photonic channelizers may perform both channelization and down-conversion in an optical domain. PMID:22319352

  4. A moving hum filter to suppress rotor noise in high-resolution airborne magnetic data

    USGS Publications Warehouse

    Xia, J.; Doll, W.E.; Miller, R.D.; Gamey, T.J.; Emond, A.M.

    2005-01-01

    A unique filtering approach is developed to eliminate helicopter rotor noise. It is designed to suppress harmonic noise from a rotor that varies slightly in amplitude, phase, and frequency and that contaminates aero-magnetic data. The filter provides a powerful harmonic noise-suppression tool for data acquired with modern large-dynamic-range recording systems. This three-step approach - polynomial fitting, bandpass filtering, and rotor-noise synthesis - significantly reduces rotor noise without altering the spectra of signals of interest. Two steps before hum filtering - polynomial fitting and bandpass filtering - are critical to accurately model the weak rotor noise. During rotor-noise synthesis, amplitude, phase, and frequency are determined. Data are processed segment by segment so that there is no limit on the length of data. The segment length changes dynamically along a line based on modeling results. Modeling the rotor noise is stable and efficient. Real-world data examples demonstrate that this method can suppress rotor noise by more than 95% when implemented in an aeromagnetic data-processing flow. ?? 2005 Society of Exploration Geophysicists. All rights reserved.

  5. Ceramic filters

    SciTech Connect

    Holmes, B.L.; Janney, M.A.

    1995-12-31

    Filters were formed from ceramic fibers, organic fibers, and a ceramic bond phase using a papermaking technique. The distribution of particulate ceramic bond phase was determined using a model silicon carbide system. As the ceramic fiber increased in length and diameter the distance between particles decreased. The calculated number of particles per area showed good agreement with the observed value. After firing, the papers were characterized using a biaxial load test. The strength of papers was proportional to the amount of bond phase included in the paper. All samples exhibited strain-tolerant behavior.

  6. Multifunction optical filter with a Michelson-Gires-Tournois interferometer for wavelength-division-multiplexed network system applications.

    PubMed

    Dingel, B B; Izutsu, M

    1998-07-15

    We propose using a novel multifunction optical filter with a Michelson-Gires-Tournois interferometer (MGTI) for future smart wavelength-division-multiplexed network system applications. The MGTI filter is a typical Michelson interferometer in which one of its reflecting mirrors is replaced with a Gires-Tournois resonator. One unique feature of this device is that it can function as a channel-passing (CP), a channel-dropping (CD), or a wide-bandpass (BP) filter, depending on the interferometer arm-length difference. Other interesting features are that (1) the linewidths of both the CP and the CD filter are twice as narrow as that of a typical Fabry-Perot filter with similar parameters, (2) theoretical visibility is always unity regardless of the mirror reflectance value, and (3) the BP filter has an excellent boxlike response function. Numerical results showing these characteristics are presented. PMID:18087440

  7. Integrable microwave filter based on a photonic crystal delay line

    NASA Astrophysics Data System (ADS)

    Sancho, Juan; Bourderionnet, Jerome; Lloret, Juan; Combrié, Sylvain; Gasulla, Ivana; Xavier, Stephane; Sales, Salvador; Colman, Pierre; Lehoucq, Gaelle; Dolfi, Daniel; Capmany, José; de Rossi, Alfredo

    2012-09-01

    The availability of a tunable delay line with a chip-size footprint is a crucial step towards the full implementation of integrated microwave photonic signal processors. Achieving a large and tunable group delay on a millimetre-sized chip is not trivial. Slow light concepts are an appropriate solution, if propagation losses are kept acceptable. Here we use a low-loss 1.5 mm-long photonic crystal waveguide to demonstrate both notch and band-pass microwave filters that can be tuned over the 0-50-GHz spectral band. The waveguide is capable of generating a controllable delay with limited signal attenuation (total insertion loss below 10 dB when the delay is below 70 ps) and degradation. Owing to the very small footprint of the delay line, a fully integrated device is feasible, also featuring more complex and elaborate filter functions.

  8. Planar Superconducting Millimeter-Wave/Terahertz Channelizing Filter

    NASA Technical Reports Server (NTRS)

    Ehsan, Negar; U-yen, Kongpop; Brown, Ari; Hsieh, Wen-Ting; Wollack, Edward; Moseley, Samuel

    2013-01-01

    This innovation is a compact, superconducting, channelizing bandpass filter on a single-crystal (0.45 m thick) silicon substrate, which operates from 300 to 600 GHz. This device consists of four channels with center frequencies of 310, 380, 460, and 550 GHz, with approximately 50-GHz bandwidth per channel. The filter concept is inspired by the mammalian cochlea, which is a channelizing filter that covers three decades of bandwidth and 3,000 channels in a very small physical space. By using a simplified physical cochlear model, and its electrical analog of a channelizing filter covering multiple octaves bandwidth, a large number of output channels with high inter-channel isolation and high-order upper stopband response can be designed. A channelizing filter is a critical component used in spectrometer instruments that measure the intensity of light at various frequencies. This embodiment was designed for MicroSpec in order to increase the resolution of the instrument (with four channels, the resolution will be increased by a factor of four). MicroSpec is a revolutionary wafer-scale spectrometer that is intended for the SPICA (Space Infrared Telescope for Cosmology and Astrophysics) Mission. In addition to being a vital component of MicroSpec, the channelizing filter itself is a low-resolution spectrometer when integrated with only an antenna at its input, and a detector at each channel s output. During the design process for this filter, the available characteristic impedances, possible lumped element ranges, and fabrication tolerances were identified for design on a very thin silicon substrate. Iterations between full-wave and lumped-element circuit simulations were performed. Each channel s circuit was designed based on the availability of characteristic impedances and lumped element ranges. This design was based on a tabular type bandpass filter with no spurious harmonic response. Extensive electromagnetic modeling for each channel was performed. Four channels

  9. All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering.

    PubMed

    Wu, Yingchen; Huang, Qiangsheng; Keyvaninia, Shahram; Katumba, Andrew; Zhang, Jing; Xie, Weiqiang; Morthier, Geert; He, Jian-Jun; Roelkens, Gunther

    2016-09-01

    We demonstrate all-optical wavelength conversion (AOWC) of non-return-to-zero (NRZ) signal based on cross-gain modulation in a single heterogeneously integrated III-V-on-silicon semiconductor optical amplifier (SOA) with an optical bandpass filter. The SOA is 500 μm long and consumes less than 250 mW electrical power. We experimentally demonstrate 12.5 Gb/s and 40 Gb/s AOWC for both wavelength up and down conversion. PMID:27607638

  10. Perception of Filtered Speech by Children with Developmental Dyslexia and Children with Specific Language Impairments.

    PubMed

    Goswami, Usha; Cumming, Ruth; Chait, Maria; Huss, Martina; Mead, Natasha; Wilson, Angela M; Barnes, Lisa; Fosker, Tim

    2016-01-01

    Here we use two filtered speech tasks to investigate children's processing of slow (<4 Hz) versus faster (∼33 Hz) temporal modulations in speech. We compare groups of children with either developmental dyslexia (Experiment 1) or speech and language impairments (SLIs, Experiment 2) to groups of typically-developing (TD) children age-matched to each disorder group. Ten nursery rhymes were filtered so that their modulation frequencies were either low-pass filtered (<4 Hz) or band-pass filtered (22 - 40 Hz). Recognition of the filtered nursery rhymes was tested in a picture recognition multiple choice paradigm. Children with dyslexia aged 10 years showed equivalent recognition overall to TD controls for both the low-pass and band-pass filtered stimuli, but showed significantly impaired acoustic learning during the experiment from low-pass filtered targets. Children with oral SLIs aged 9 years showed significantly poorer recognition of band pass filtered targets compared to their TD controls, and showed comparable acoustic learning effects to TD children during the experiment. The SLI samples were also divided into children with and without phonological difficulties. The children with both SLI and phonological difficulties were impaired in recognizing both kinds of filtered speech. These data are suggestive of impaired temporal sampling of the speech signal at different modulation rates by children with different kinds of developmental language disorder. Both SLI and dyslexic samples showed impaired discrimination of amplitude rise times. Implications of these findings for a temporal sampling framework for understanding developmental language disorders are discussed. PMID:27303348

  11. Perception of Filtered Speech by Children with Developmental Dyslexia and Children with Specific Language Impairments

    PubMed Central

    Goswami, Usha; Cumming, Ruth; Chait, Maria; Huss, Martina; Mead, Natasha; Wilson, Angela M.; Barnes, Lisa; Fosker, Tim

    2016-01-01

    Here we use two filtered speech tasks to investigate children’s processing of slow (<4 Hz) versus faster (∼33 Hz) temporal modulations in speech. We compare groups of children with either developmental dyslexia (Experiment 1) or speech and language impairments (SLIs, Experiment 2) to groups of typically-developing (TD) children age-matched to each disorder group. Ten nursery rhymes were filtered so that their modulation frequencies were either low-pass filtered (<4 Hz) or band-pass filtered (22 – 40 Hz). Recognition of the filtered nursery rhymes was tested in a picture recognition multiple choice paradigm. Children with dyslexia aged 10 years showed equivalent recognition overall to TD controls for both the low-pass and band-pass filtered stimuli, but showed significantly impaired acoustic learning during the experiment from low-pass filtered targets. Children with oral SLIs aged 9 years showed significantly poorer recognition of band pass filtered targets compared to their TD controls, and showed comparable acoustic learning effects to TD children during the experiment. The SLI samples were also divided into children with and without phonological difficulties. The children with both SLI and phonological difficulties were impaired in recognizing both kinds of filtered speech. These data are suggestive of impaired temporal sampling of the speech signal at different modulation rates by children with different kinds of developmental language disorder. Both SLI and dyslexic samples showed impaired discrimination of amplitude rise times. Implications of these findings for a temporal sampling framework for understanding developmental language disorders are discussed. PMID:27303348

  12. Effects of Filtering on Experimental Blast Overpressure Measurements.

    PubMed

    Alphonse, Vanessa D; Kemper, Andrew R; Duma, Stefan M

    2015-01-01

    When access to live-fire test facilities is limited, experimental studies of blast-related injuries necessitate the use of a shock tube or Advanced Blast Simulator (ABS) to mimic free-field blast overpressure. However, modeling blast overpressure in a laboratory setting potentially introduces experimental artifacts in measured responses. Due to the high sampling rates required to capture a blast overpressure event, proximity to alternating current (AC-powered electronics) and poorly strain-relieved or unshielded wires can result in artifacts in the recorded overpressure trace. Data in this study were collected for tests conducted on an empty ABS (“Empty Tube”) using high frequency pressure sensors specifically designed for blast loading rates (n=5). Additionally, intraocular overpressure data (“IOP”) were collected for porcine eyes potted inside synthetic orbits located inside the ABS using an unshielded miniature pressure sensor (n=3). All tests were conducted at a 30 psi static overpressure level. A 4th order phaseless low pass Butterworth software filter was applied to the data. Various cutoff frequencies were examined to determine if the raw shock wave parameters values could be preserved while eliminating noise and artifacts. A Fast Fourier Transform (FFT) was applied to each test to examine the frequency spectra of the raw and filtered signals. Shock wave parameters (time of arrival, peak overpressure, positive duration, and positive impulse) were quantified using a custom MATLAB® script. Lower cutoff frequencies attenuated the raw signal, effectively decreasing the peak overpressure and increasing the positive duration. Rise time was not preserved the filtered data. A CFC 6000 filter preserved the remaining shock wave parameters within ±2.5% of the average raw values for the Empty Tube test data. A CFC 7000 filter removed experimental high-frequency artifacts and preserved the remaining shock wave parameters within ±2.5% of the average raw values for

  13. Novel Hexagonal Dual-Mode Substrate Integrated Waveguide Filter with Source-Load Coupling

    PubMed Central

    Zhang, Gen; Xu, Meijuan

    2014-01-01

    Hexagonal dual-mode cavity and its application to substrate integrated waveguide (SIW) filter are presented. The hexagonal SIW resonator which can combine flexibility of rectangular cavity and performance of circular cavity is convenient for dual-mode bandpass filters design. By introducing coupling between source and load, the filter not only has good selectivity due to two controllable transmission zeros, but also has a small size by the virtue of its single-cavity structure. A demonstration filter with a center frequency of 10 GHz and a 3 dB fractional bandwidth of 4% is designed and fabricated to validate the proposed structure. Measured results are in good agreement with simulated ones. PMID:24895669

  14. Novel hexagonal dual-mode substrate integrated waveguide filter with source-load coupling.

    PubMed

    Xu, Ziqiang; Zhang, Gen; Xia, Hong; Xu, Meijuan

    2014-01-01

    Hexagonal dual-mode cavity and its application to substrate integrated waveguide (SIW) filter are presented. The hexagonal SIW resonator which can combine flexibility of rectangular cavity and performance of circular cavity is convenient for dual-mode bandpass filters design. By introducing coupling between source and load, the filter not only has good selectivity due to two controllable transmission zeros, but also has a small size by the virtue of its single-cavity structure. A demonstration filter with a center frequency of 10 GHz and a 3 dB fractional bandwidth of 4% is designed and fabricated to validate the proposed structure. Measured results are in good agreement with simulated ones. PMID:24895669

  15. JPL activities on development of acousto-optic tunable filter imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Chao, Tien-Hsin; Reyes, George

    1992-01-01

    Recent activities of JPL in the development of a new type of imaging spectrometers for earth observation and planetary exploration are reported. This instrument uses the acousto-optic tunable filter (AOTF) as high resolution and fast programmable bandpass filter. AOTF operates in the principle of acousto-optic interaction in an anisotropic medium. This filter can be tuned in sequential, random, and multiwavelength access modes, providing observational flexibility. The diffraction process in the filter generates two diffracted monochromatic beams with polarization orthogonal to each other, creating a unique capability to measure both polarimetric and spectral properties of the incoming light simultaneously with a single instrument. The device gives wide wavelength operations with reasonably large throughput. In addition, it is in a compact solid-state structure without moving parts, providing system reliability. These attractive features give promising opportunities to develop a new generation of airborne/spaceborne and ground, real-time, imaging spectrometer systems for remote sensing applications.

  16. Dichroic filters to protect milliwatt far-infrared detectors from megawatt ECRH radiation.

    PubMed

    Bertschinger, G; Endres, C P; Lewen, F; Oosterbeek, J W

    2008-10-01

    Dichroic filters have been used to shield effectively the far infrared (FIR) detectors at the interferometer/polarimeter on TEXTOR. The filters consist of metal foils with regular holes, the hole diameter, the mutual spacing and the thickness of the foils are chosen to transmit radiation at the design frequency with transmission >90%. The attenuation at the low frequency end of the bandpass filter is about 30 dB per octave, the high frequency transmission is between 20% and 40%. The filters have been used to block the stray radiation from the megawatt microwave heating beam to the detectors of the FIR interferometer, operating with power on the detector in the milliwatt range. If required, the low frequency attenuation can be still enhanced, without compromising the transmission in the passband. The FIR interferometer used for plasma density and position control is no longer disturbed by electromagnetic waves used for plasma heating. PMID:19044527

  17. Dichroic filters to protect milliwatt far-infrared detectors from megawatt ECRH radiation

    NASA Astrophysics Data System (ADS)

    Bertschinger, G.; Endres, C. P.; Lewen, F.; Oosterbeek, J. W.

    2008-10-01

    Dichroic filters have been used to shield effectively the far infrared (FIR) detectors at the interferometer/polarimeter on TEXTOR. The filters consist of metal foils with regular holes, the hole diameter, the mutual spacing and the thickness of the foils are chosen to transmit radiation at the design frequency with transmission >90%. The attenuation at the low frequency end of the bandpass filter is about 30dB per octave, the high frequency transmission is between 20% and 40%. The filters have been used to block the stray radiation from the megawatt microwave heating beam to the detectors of the FIR interferometer, operating with power on the detector in the milliwatt range. If required, the low frequency attenuation can be still enhanced, without compromising the transmission in the passband. The FIR interferometer used for plasma density and position control is no longer disturbed by electromagnetic waves used for plasma heating.

  18. Dichroic filters to protect milliwatt far-infrared detectors from megawatt ECRH radiation

    SciTech Connect

    Bertschinger, G.; Oosterbeek, J. W.; Endres, C. P.; Lewen, F.

    2008-10-15

    Dichroic filters have been used to shield effectively the far infrared (FIR) detectors at the interferometer/polarimeter on TEXTOR. The filters consist of metal foils with regular holes, the hole diameter, the mutual spacing and the thickness of the foils are chosen to transmit radiation at the design frequency with transmission >90%. The attenuation at the low frequency end of the bandpass filter is about 30 dB per octave, the high frequency transmission is between 20% and 40%. The filters have been used to block the stray radiation from the megawatt microwave heating beam to the detectors of the FIR interferometer, operating with power on the detector in the milliwatt range. If required, the low frequency attenuation can be still enhanced, without compromising the transmission in the passband. The FIR interferometer used for plasma density and position control is no longer disturbed by electromagnetic waves used for plasma heating.

  19. MMTF: THE MARYLAND-MAGELLAN TUNABLE FILTER

    SciTech Connect

    Veilleux, S.; Weiner, B. J.; Rupke, D. S. N. E-mail: bjw@as.arizona.edu

    2010-01-15

    This paper describes the Maryland-Magellan Tunable Filter (MMTF) on the Magellan-Baade 6.5 m telescope. MMTF is based on a 150 mm clear aperture Fabry-Perot (FP) etalon that operates in low orders and provides transmission bandpass and central wavelength adjustable from {approx}5 A to {approx}15 A and from {approx}5000 A to over {approx}9200 A, respectively. It is installed in the Inamori Magellan Areal Camera and Spectrograph and delivers an image quality of {approx}0.''5 over a field of view of 27' in diameter (monochromatic over {approx}10'). This versatile and easy-to-operate instrument has been used over the past three years for a wide variety of projects. This paper first reviews the basic principles of FP tunable filters, and then provides a detailed description of the hardware and software associated with MMTF and the techniques developed to observe with this instrument and reduce the data. The main lessons learned in the course of the commissioning and implementation of MMTF are highlighted next, before concluding with a brief outlook on the future of MMTF and of similar facilities which are soon coming on line.

  20. MMTF: The Maryland-Magellan Tunable Filter

    NASA Astrophysics Data System (ADS)

    Veilleux, S.; Weiner, B. J.; Rupke, D. S. N.; McDonald, M.; Birk, C.; Bland-Hawthorn, J.; Dressler, A.; Hare, T.; Osip, D.; Pietraszewski, C.; Vogel, S. N.

    2010-01-01

    This paper describes the Maryland-Magellan Tunable Filter (MMTF) on the Magellan-Baade 6.5 m telescope. MMTF is based on a 150 mm clear aperture Fabry-Perot (FP) etalon that operates in low orders and provides transmission bandpass and central wavelength adjustable from ~5 Å to ~15 Å and from ~5000 Å to over ~9200 Å, respectively. It is installed in the Inamori Magellan Areal Camera and Spectrograph and delivers an image quality of ~0farcs5 over a field of view of 27' in diameter (monochromatic over ~10'). This versatile and easy-to-operate instrument has been used over the past three years for a wide variety of projects. This paper first reviews the basic principles of FP tunable filters, and then provides a detailed description of the hardware and software associated with MMTF and the techniques developed to observe with this instrument and reduce the data. The main lessons learned in the course of the commissioning and implementation of MMTF are highlighted next, before concluding with a brief outlook on the future of MMTF and of similar facilities which are soon coming on line.

  1. Monolithically Integrated Reconfigurable Filters for Microwave Photonic Links

    NASA Astrophysics Data System (ADS)

    Norberg, Erik J.

    For the purposes of commercial communication and military electronic warfare and radar alike, there is an increasing interest in RF systems that can handle very wide instantaneous bandwidths at high center frequencies. Optical signal processing has the capability to reduce latency, improve size, weight and power (SwAP) performance, and overcome the inherent bandwidth limitations of electronic counterparts. By rapidly pre-filtering wide bandwidth microwave signals in the optical domain, the analog-to-digital conversion (ADC) and subsequent digital signal processing (DSP) can be significantly relieved. Compared to channelizing and add/drop filters for wavelength division multiplexing (WDM) applications, the microwave filter application is much more challenging as it requires a more versatile filter, ideally with tunability in both frequency and bandwidth. In this work such a filter was developed using integrated photonics. By integrating the filter on a single InP chip, the stability required for coherent filtering is met, while the active integration platform offers a flexible filter design and higher tolerance in the coupler and fabrication specifications. Using an entirely deep etched fabrication with a single blanket regrowth, a simple fabrication with high yield is achieved. The reconfigurable filter is designed as an array of uncoupled filter stages with each filter stage reconfigurable as a filter pole or zero with arbitrary magnitude and phase. This gives rise to a flexible ffilter synthesis, much like an optical version of DSP filters. Flat-topped bandpass filters are demonstrated with frequency tunability over 30 GHz, bandwidth adjustable between 1.9 and 5.4 GHz, and stopband rejection >32 dB. In order to meet the stringent spurious-free dynamic range (SFDR) requirements of the microwave application, a novel epitaxial layer integration platform is developed. Optimized for high optical saturation power and low propagation loss, it produces semiconductor

  2. Method for improving line flux and redshift measurements with narrowband filters

    NASA Astrophysics Data System (ADS)

    Zabl, J.; Freudling, W.; Møller, P.; Milvang-Jensen, B.; Nilsson, K. K.; Fynbo, J. P. U.; Le Fèvre, O.; Tasca, L. A. M.

    2016-05-01

    Context. High redshift star-forming galaxies are discovered routinely because of a flux excess in narrowband filters caused by an emission line. In most cases, the width of such filters is broader than typical line widths, and the throughput of the filters varies substantially within the bandpass. This leads to substantial uncertainties in redshifts and fluxes that are derived from the observations with one specific narrowband filter. Aims: The uncertainty in measured line parameters can be sharply reduced by using repeated observations of the same target field with filters that have overlapping passbands but differ slightly in central wavelength or wavelength dependence of the effective filter curve. Such data are routinely collected with some large field imaging cameras that use multiple detectors and a separate filter for each of the detectors. An example is the European Southern Observatory's VISTA InfraRed CAMera (VIRCAM). Methods: We developed a method of determining more accurate redshift and line flux estimates from the ratio of apparent fluxes measured from observations in different narrowband filters and several matching broadband filters. A parameterized model of the line and continuum flux is used to predict the flux ratios as a function of redshift based on the known filter curves. These model predictions are then used to determine the most likely redshift and line flux. Results: We tested the obtainable quality of parameter estimation for the example of Hα in the VIRCAM NB118 filters both on simulated and actual observations where the latter were based on the UltraVISTA DR2 data set. We combined the narrowband data with deep broadband data in Y, J, and H. We find that with this method, the errors in the measured lines fluxes can be reduced up to almost an order of magnitude. Conclusions: We conclude that existing narrowband data can be used to derive accurate line fluxes if the observations include images taken with sufficiently different filter

  3. Ultra-wideband ladder filter using SH(0) plate wave in thin LiNbO(3) plate and its application to tunable filter.

    PubMed

    Kadota, Michio; Tanaka, Shuji

    2015-05-01

    A cognitive radio terminal using vacant frequency bands of digital TV (DTV) channels, i.e., TV white space, strongly requires a compact tunable filter covering a wide frequency range of the DTV band (470 to 710 MHz in Japan). In this study, a T-type ladder filter using ultra-wideband shear horizontal mode plate wave resonators was fabricated, and a low peak insertion loss of 0.8 dB and an ultra-large 6 dB bandwidth of 240 MHz (41%) were measured in the DTV band. In addition, bandpass filters with different center frequencies of 502 and 653 MHz at 6 dB attenuation were numerically synthesized based on the same T-type ladder filter in conjunction with band rejection filters with different frequencies. The results suggest that the combination of the wideband T-type ladder filter and the band rejection filters connected with variable capacitors enables a tunable filter with large tunability of frequency and bandwidth as well as large rejection at the adjacent channels of an available TV white space. PMID:25965686

  4. The use of linear programming techniques to design optimal digital filters for pulse shaping and channel equalization

    NASA Technical Reports Server (NTRS)

    Houts, R. C.; Burlage, D. W.

    1972-01-01

    A time domain technique is developed to design finite-duration impulse response digital filters using linear programming. Two related applications of this technique in data transmission systems are considered. The first is the design of pulse shaping digital filters to generate or detect signaling waveforms transmitted over bandlimited channels that are assumed to have ideal low pass or bandpass characteristics. The second is the design of digital filters to be used as preset equalizers in cascade with channels that have known impulse response characteristics. Example designs are presented which illustrate that excellent waveforms can be generated with frequency-sampling filters and the ease with which digital transversal filters can be designed for preset equalization.

  5. Revised Filter Profiles and Zero Points for Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew W.; von Braun, Kaspar

    2015-02-01

    Estimating accurate bolometric fluxes for stars requires reliable photometry to absolutely flux calibrate the spectra. This is a significant problem for studies of very bright stars, which are generally saturated in modern photometric surveys. Instead we must rely on photometry with less precise calibration. We utilize precisely flux-calibrated spectra to derive improved filter bandpasses and zero points for the most common sources of photometry for bright stars. In total, we test 39 different filters in the General Catalog of Photometric Data as well as those from Tycho-2 and Hipparcos. We show that utilizing inaccurate filter profiles from the literature can create significant color terms resulting in fluxes that deviate by gsim10% from actual values. To remedy this we employ an empirical approach; we iteratively adjust the literature filter profile and zero point, convolve it with catalog spectra, and compare to the corresponding flux from the photometry. We adopt the passband values that produce the best agreement between photometry and spectroscopy and are independent of stellar color. We find that while most zero points change by < 5%, a few systems change by 10-15%. Our final profiles and zero points are similar to recent estimates from the literature. Based on determinations of systematic errors in our selected spectroscopic libraries, we estimate that most of our improved zero points are accurate to 0.5-1%.

  6. High Q printed helical resonators for oscillators and filters.

    PubMed

    Everard, Jeremy K A; Broomfield, Carl D

    2007-09-01

    High Q compact printed helical resonators which operate from around 1.8 to 2 GHz are described. These consist of a multilayer printed circuit board (PCB) incorporating a printed helical transmission line. Loss in the via hole is reduced by ensuring that the standing wave current at this point is near zero. This ensures a significant increase in Q. Further increased energy storage per unit volume is achieved due to the 3-D helical nature of the resonator. Unloaded Qs of 235 and 195 have been obtained on low loss PCBs with dielectric constants of 2.2 and 10.5, respectively. Two applications for these resonators are described in this paper. The first is the design of a compact low noise oscillator where the ratio of QL/Q0, and hence insertion loss, is adjusted for low noise. The 2-GHz oscillator demonstrates a phase noise of -120 dBc/Hz at 10 kHz which is predicted exactly by the theory. The second is a three-section filter designed to offer the response required by the front end filter of a modern GSM mobile telephone. In the filter design three helical resonators are coupled together to produce a completely printed triplate bandpass filter. PMID:17941381

  7. In situ calibration of tunable filters: Lyot and Michelson.

    PubMed

    Mudge, Jason; Tarbell, Theodore

    2014-08-01

    Solar imaging optical filter technology has progressed significantly over the past 75 years, and the ability to tune narrowband filters is particularly valuable for solar atmosphere sensing. For example, imaging while tuning over a narrow solar spectral line (emission or absorption) provides two-dimensional measurements of Doppler shifts and magnetic fields. While tuning ability has improved significantly, tuning accuracy can be a challenge over time given system actuator drifts. For many cases, the ability to calibrate these actuators in situ is convenient and cost effective (e.g., ground-based observatories), and for other cases it is required (e.g., in a spacecraft). It is ideal to calibrate in situ without the need for additional hardware such as a spectrometer, and if that cannot be achieved, the next best thing is to do so with minimum additional hardware. Two examples of solar filters that need to be calibrated periodically are: (1) a liquid crystal variable retarder Lyot filter and (2) a tunable Michelson interferometer. For the first, the filter can have a number of stages back-to-back to achieve the desired finesse. Within each stage there is a liquid crystal variable retarder that adds some amount of retardance to the stage's fixed birefringent crystal; this provides wavelength bandpass tuning. For the second, there can be several Michelson interferometers in series each with an actuator to adjust the optical path length in one of its optical paths for tuning. The stacking of these filters implies there is a need to calibrate more than one actuator. An algorithm has been developed to calibrate these types of stacked and nonstacked filters in situ with minimal, if any, hardware additions. PMID:25090330

  8. HEPA filter dissolution process

    SciTech Connect

    Brewer, K.N.; Murphy, J.A.

    1992-12-31

    This invention is comprised of a process for dissolution of spent high efficiency particulate air (HEPA) filters and then combining the complexed filter solution with other radioactive wastes prior to calcining the mixed and blended waste feed. The process is an alternate to a prior method of acid leaching the spent filters which is an inefficient method of treating spent HEPA filters for disposal.

  9. Recirculating electric air filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  10. Hepa filter dissolution process

    DOEpatents

    Brewer, Ken N.; Murphy, James A.

    1994-01-01

    A process for dissolution of spent high efficiency particulate air (HEPA) filters and then combining the complexed filter solution with other radioactive wastes prior to calcining the mixed and blended waste feed. The process is an alternate to a prior method of acid leaching the spent filters which is an inefficient method of treating spent HEPA filters for disposal.

  11. HEPA filter dissolution process

    DOEpatents

    Brewer, K.N.; Murphy, J.A.

    1994-02-22

    A process is described for dissolution of spent high efficiency particulate air (HEPA) filters and then combining the complexed filter solution with other radioactive wastes prior to calcining the mixed and blended waste feed. The process is an alternate to a prior method of acid leaching the spent filters which is an inefficient method of treating spent HEPA filters for disposal. 4 figures.

  12. Recirculating electric air filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  13. Tunable millimeter-wave filters using a coplanar waveguide and micromachined variable capacitors

    NASA Astrophysics Data System (ADS)

    Park, Jae-Hyoung; Kim, Hong-Teuk; Kwon, Youngwoo; Kim, Yong-Kweon

    2001-11-01

    In this paper, new micromachined tunable bandpass filters for multi-band millimeter-wave telecommunication systems are proposed. Two types of millimeter-wave tunable filters have been fabricated using micromachining technology and the responses of the filters have been measured: one type is a two-pole lumped element filter and the other a two-pole resonator filter. The frequency tunability of the filter has been achieved by changing the gap between a common coplanar waveguide ground plate and a movable cantilever beam connected to the transmission line with a controllable range of 2.5 µm. The deflection of the cantilever beam has been measured with applied dc voltage. With the applied bias voltage from 0 to 50 V, the fabricated filters have shown center frequency shifts of 0.6 GHz (2.3%) at 26.6 GHz and 0.8 GHz (2.5%) at 32 GHz for the lumped element and resonator filters, respectively. The mechanical lifetime of the fabricated gold cantilever structure has been tested by observing the existence of the spring memory phenomenon; there is no memory phenomenon or breakdown until a repeated actuation of 1.6×108 cycles.

  14. Use of acousto-optic tunable filter in fluorescence imaging endoscopy

    NASA Astrophysics Data System (ADS)

    Bouhifd, Mounir; Whelan, Maurice; Aprahamian, Marc

    2003-10-01

    A prototype instrument for fluorescence-based medical diagnostics in vivo is described. The system consists of a rigid endoscope comprising a UV laser-source for fluorescence excitation and a white light source for direct imaging. An acousto-optic tuneable filter (AOTF) is employed as a full-field tuneable bandpass filter. This allows fast continuous or random-access tuning with high filtering efficiency. A study of the diagnostic potential of fluorescence imaging for pancreatitis was conducted on a rat model. In particular, the aim was to detect autofluorescence of endogenous protoporphyrin IX (PpIX) that has been shown to accumulate in early-stage diseased tissue undergoing an inflammatory response.

  15. A VHF band HTS filter based on modified single-spiral resonators for radio astronomy application

    NASA Astrophysics Data System (ADS)

    Li, Chao; Sun, Liang; Wang, Jia; Bian, YongBo; Yu, Tao; Li, Fei; Li, ChunGuang; Li, Hong; Gu, ChangZhi; He, YuSheng

    2013-05-01

    A 10-pole quasi-elliptic bandpass filter (BPF) with a relatively wide passband in the very high frequency (VHF) band was designed and fabricated using YBCO thin films deposited on both sides of a LaAlO3 substrate. Single-spiral resonators were modified to generate strong coupling and reduce the parasitic coupling. We analysed the coupling polarities between the modified resonators. Two pairs of attenuation poles were introduced in the filter for sharp cut-off response. The measurements showed that the filter has a centre frequency of 255.8 MHz, fractional bandwidth of about 12.3%, insertion loss of smaller than 0.265 dB, and the return loss in the passband of better than 17.5 dB, in good agreement with computer simulations.

  16. Triple-band high-temperature superconducting microstrip filter based on multimode split ring resonator

    NASA Astrophysics Data System (ADS)

    Liu, Hai-Wen; Wang, Yan; Fan, Yi-Chao; Guan, Xue-Hui; He, Yusheng

    2013-09-01

    A compact triple-band high-temperature superconducting (HTS) YBa2Cu3Oy microstrip bandpass filter using multimode split ring resonator (SRR) is presented in this letter. Also, its properties and equivalent circuit models are investigated by even- and odd-mode analysis. Moreover, design method of the proposed triple-band HTS filter for the applications of global positioning system at 1.57 GHz, worldwide interoperability for microwave access at 3.5 GHz, and wireless local area networks at 5.8 GHz is discussed. The centre frequencies and the bandwidths of the three passbands can be allocated properly choosing the dimension parameters of the multimode SRR. In addition, four transmission zeros are produced to improve the selectivity of this filter.

  17. Hemispherical concentrators and spectral filters for planar sensors in diffuse radiation fields.

    PubMed

    Savicki, J P; Morgan, S P

    1994-12-01

    A dielectric hemisphere of refractive index N can act as an N(2) concentrator of isotropic diffuse radiation under appropriate conditions. We give an analytic expression for the gain of a concentrator of arbitrary radius, neglecting surface reflections, and numerical methods for calculating the gain when the surface transmissivity is an arbitrary function of incidence angle. The theory is applied to the design of multilayer spectral filters for hemispherical concentrators. When an appropriate wavelength shift is incorporated into the design process, an 11-layer, coupled-cavity spectral filter on the surface of a hemisphere of index 1.5 shows excellent bandpass performance with a concentrator radius as small as 3 times the sensor radius. This concentrator-filter combination shows a peak response of 97% of the ideal N(2) response at 950 nm, together with a FWHM of 55 nm. PMID:20963025

  18. Polarization-independent visible wavelength filter incorporating a symmetric metal-dielectric resonant structure.

    PubMed

    Park, Chang-Hyun; Yoon, Yeo-Taek; Lee, Sang-Shin

    2012-10-01

    A nanophotonic polarization-independent visible wavelength filter is presented, incorporating a symmetric metal-dielectric resonant structure on quartz substrate, where a sub-wavelength grating, made up of a two-dimensional array of Al square sheets, is integrated with a Si(3)N(4) slab waveguide via an oxide layer. Incident light is orthogonally diffracted by the symmetric grating towards two directions of the grating groove, and then resonantly coupled to both transverse electric and transverse magnetic guided modes associated with the underlying waveguide, irrespective of light polarization. Polarization independent bandpass filtering was thus achieved around specific wavelengths, determined by the grating pitch and the effective index of the waveguide. Three devices, operating in the blue, green and red spectral bands, were built through design and analysis drawing upon the finite-difference time-domain method. The devices, DEV I, II, and III, were constructed with grating pitches of 285, 355 and 395 nm, respectively, while the core was 100 nm thick. They were inspected to function as an efficient bandpass filter, centered at 460, 560 and 610 nm, with bandwidths of about 13, 14 and 17 nm, respectively; the peak transmission efficiencies were consistently over 85%. Furthermore, the transfer characteristics, insensitive to light polarization, were satisfactorily confirmed for normal incidence. PMID:23188342

  19. a High Temperature Superconductor Microwave Filter Working in C-Band for the Sardinia Radio Telescope

    NASA Astrophysics Data System (ADS)

    Bolli, P.; Cresci, L.; Huang, F.; Mariotti, S.; Panella, D.

    A planar band-pass filter based on High Temperature Superconductor (HTS) has been designed for possible implementation in the cryogenic front-end of the C-band receiver for the Sardinia Radio Telescope. The band-pass filter is designed to operate at relatively high frequencies: center frequency 6.7 GHz with 30% bandwidth. Seven nominally identical filters have been fabricated to test different carrier materials and connector types aimed to keep the fabrication of the HTS filter simpler and more cost competitive. In addition to the conventional approach, silver plating, copper carriers and SMA connectors have been used. Cryogenic scattering parameter measurements show a good agreement with numerical results: the average of the transmission losses turns out to be in the range 0.15-0.25 dB depending on the prototypes, whereas the reflection coefficient is below -16 dB. The insertion loss has been also measured by using a radiometric approach based on the cold attenuator method showing consistent results with those given by the Vector Network Analyzer. Multiple cool-down measurements have been performed successfully proving the data repeatability both in short- and medium-term. Concerning alternative technical solutions, the SMA connectors and silver plating appear to be valid options whereas the copper carriers are inclined to destroy the circuit. Finally, numerical simulations and experimental measurements on a traditional copper filter operating at 20 K show that the HTS filter improves the losses of about 0.2 dB with respect to the copper one.

  20. On easily tunable wide-bandpass X-ray monochromators based on refraction in arrays of prisms.

    PubMed

    Jark, Werner

    2012-07-01

    Refractive lenses focus X-rays chromatically owing to a significant variation of the refractive index of the lens material with photon energy. Then, in combination with an exit slit in the focal plane, such lenses can be used as monochromators. The spectral resolution obtainable with refractive lenses based on prism arrays was recently systematically investigated experimentally. This contribution will show that a wide-bandpass performance can be predicted with a rather simple analytical approach. Based on the good agreement with the experimental data, one can then more rapidly and systematically optimize the lens structure for a given application. This contribution will then discuss more flexible solutions for the monochromator operation. It will be shown that a new monochromator scheme could easily provide tuning in a fixed-exit slit. PMID:22713879

  1. ARRANGEMENT FOR REPLACING FILTERS

    DOEpatents

    Blomgren, R.A.; Bohlin, N.J.C.

    1957-08-27

    An improved filtered air exhaust system which may be continually operated during the replacement of the filters without the escape of unfiltered air is described. This is accomplished by hermetically sealing the box like filter containers in a rectangular tunnel with neoprene covered sponge rubber sealing rings coated with a silicone impregnated pneumatic grease. The tunnel through which the filters are pushed is normal to the exhaust air duct. A number of unused filters are in line behind the filters in use, and are moved by a hydraulic ram so that a fresh filter is positioned in the air duct. The used filter is pushed into a waiting receptacle and is suitably disposed. This device permits a rapid and safe replacement of a radiation contaminated filter without interruption to the normal flow of exhaust air.

  2. Extreme-ultraviolet calibration of thin-film Zr filters for the cosmic hot interstellar plasma spectrometer.

    PubMed

    Hemphill, Richelieu; Pelizzo, Maria G; Hurwitz, Mark

    2002-08-01

    The design and calibration of thin-film Zr transmission filters for the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) spaceborne astronomical telescope is presented. The transmission of a 1,000-A-thick Zr filter is measured for wavelengths from 45 to 1,304 A as well as its variability with respect to expected space-flight enviromental extremes of temperature, vibration, and atomic O bombardment. For the CHIPS spectral band of 90-260 A, the transmission of the Zr fiter is deemed useful between 90 and 200 A and is stable with respect to expected temperature and vibrational changes. The maximum atomic O bombardment decreases the filter transmission between 90 and 130 A by approximately 20% and does not appreciably affect the rest of the CHIPS bandpass. These results make Zr an acceptable filter candidate for CHIPS. PMID:12153103

  3. On-chip Optical Filters with Designable Characteristics Based on an Interferometer with Embedded Silicon Photonic Structures

    SciTech Connect

    Lu, M.; Kocaman, S.; Aras, M.S.; Panoiu, N.C.; Wong, C.W.

    2012-02-15

    We demonstrate chip-scale flat-top filters at near-IR wavelengths using negative index photonic crystal based Mach-Zehnder interferometers. Supported by full three-dimensional numerical simulations, we experimentally demonstrate a new approach for engineering high-pass, low-pass, bandpass, and band-reject filters, based on designing the photonic band diagram both within the bandgap frequency region and away from it. We further show that our approach can be used to design filters that have tunable multilevel response for different sections of the spectrum and for different polarizations. This configuration enables deterministic control of the bandwidth and the rejection ratio of filters for integrated photonic circuits.

  4. On-chip copper-dielectric interference filters for manufacturing of ambient light and proximity CMOS sensors.

    PubMed

    Frey, Laurent; Masarotto, Lilian; D'Aillon, Patrick Gros; Pellé, Catherine; Armand, Marilyn; Marty, Michel; Jamin-Mornet, Clémence; Lhostis, Sandrine; Le Briz, Olivier

    2014-07-10

    Filter technologies implemented on CMOS image sensors for spectrally selective applications often use a combination of on-chip organic resists and an external substrate with multilayer dielectric coatings. The photopic-like and near-infrared bandpass filtering functions respectively required by ambient light sensing and user proximity detection through time-of-flight can be fully integrated on chip with multilayer metal-dielectric filters. Copper, silicon nitride, and silicon oxide are the materials selected for a technological proof-of-concept on functional wafers, due to their immediate availability in front-end semiconductor fabs. Filter optical designs are optimized with respect to specific performance criteria, and the robustness of the designs regarding process errors are evaluated for industrialization purposes. PMID:25090070

  5. Corrosion resistant filter unit

    SciTech Connect

    Gentry, J.M.

    1992-02-18

    This patent describes a fluid filter assembly adapted for the filtration of corrosive fluid to be injected into a well bore at pressure levels which may exceed 10,000 pounds per square. It comprises: a frame assembly for the mounting of a portion of the fluid filter assembly therein, the frame assembly; filter pods, the plurality of filter pods forming at least two banks of filter pods, each bank having at least two filter pods therein, each bank of the filter pods being supported by one or more the supports of the plurality of supports secured to selected struts of the frame assembly; an inlet manifold to direct the corrosive fluid to the plurality of filter pods, the inlet manifold being interconnected to the banks of filter pods formed by the filter pods whereby flow of the corrosive fluid can be directed to each bank of the filter pods; an outlet manifold to direct the corrosive fluid from the filter pods, the outlet manifold being interconnected to the banks of filter pods formed by the filter pods; a first valve means to control the flow of the corrosive fluid between banks of filter pods formed by the filter pods whereby the flow of the corrosive fluid can be selectively directed to each bank of the filter pods; a second valve means to selectively control the flow of the corrosive fluid between the inlet manifold and the outlet manifold; and union means for interconnecting the filter pods, inlet manifold and outlet manifold, each of the union means including mechanical connection means and internal seal means for isolating the corrosive fluids from the mechanical connection means.

  6. Rigid porous filter

    DOEpatents

    Chiang, Ta-Kuan; Straub, Douglas L.; Dennis, Richard A.

    2000-01-01

    The present invention involves a porous rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.

  7. Filter type gas sampler with filter consolidation

    DOEpatents

    Miley, Harry S.; Thompson, Robert C.; Hubbard, Charles W.; Perkins, Richard W.

    1997-01-01

    Disclosed is an apparatus for automatically consolidating a filter or, more specifically, an apparatus for drawing a volume of gas through a plurality of sections of a filter, whereafter the sections are subsequently combined for the purpose of simultaneously interrogating the sections to detect the presence of a contaminant.

  8. Filter type gas sampler with filter consolidation

    DOEpatents

    Miley, H.S.; Thompson, R.C.; Hubbard, C.W.; Perkins, R.W.

    1997-03-25

    Disclosed is an apparatus for automatically consolidating a filter or, more specifically, an apparatus for drawing a volume of gas through a plurality of sections of a filter, where after the sections are subsequently combined for the purpose of simultaneously interrogating the sections to detect the presence of a contaminant. 5 figs.

  9. Narrow band pass filter using birefringence film and quarter-wave film

    NASA Astrophysics Data System (ADS)

    Lee, Dong-kun; Song, Jang-Kun

    2016-03-01

    While a pixel in a color image has three colorimetric information of RGB, that in a spectral image contains full spectral information, several tens times more information compared to the color image. Hence, the spectral image is widely applicable in biology, material science, and environmental science. Although several methods for spectral image acquisition have been suggested to date, those methods are expensive, bulky, or slow in actual device. In this work, we designed a novel type of tunable narrow band-pass filter using rotatable polarizer, quarter-wave plate, and birefringence films. Different from the conventional Lyot-Ohman type filter, we do not use a liquid crystal layer. The selection of wavelength is made by rotating the polarizer in our filter set, and adopted a piezoelectric rotational actuator for that. We simulated to find the optimal conditions of the filter set, and finally, fabricated a filter module. The minimum band width was 5 nm, which is suitable for usual spectral imaging and can be reduced further if necessary, and the wavelength of light passing through the filter set was continuously selectable. After setting the filter in a microscope, we obtained a spectral image set for a bio sample that contained full spectrum information in each pixel. Using image processing, we could demonstrate to read out the spectral information for any selected position.

  10. Design and Experimental Investigation of a Compact Circularly Polarized Integrated Filtering Antenna for Wearable Biotelemetric Devices.

    PubMed

    Jiang, Zhi Hao; Gregory, Micah D; Werner, Douglas H

    2016-04-01

    A compact circularly polarized (CP) integrated filtering antenna is reported for wearable biotelemetric devices in the 2.4 GHz ISM band. The design is based on a mutual synthesis of a CP patch antenna connected to a bandpass filter composed of coupled stripline open-loop resonators, which provides an integrated low-profile radiating and filtering module with a compact form factor of 0.44λ(0)×0.44λ(0)×0.04λ(0). The optimized filtering antenna is fabricated and measured, achieving an S11 < -14 dB, an axial ratio of less than 3 dB and gain higher than 3.5 dBi in the targeted ISM band. With the integrated filtering functionality, the antenna exhibits good out-of-band rejection over an ultra-wide frequency range of 1-6 GHz. Further full-wave simulations and experiments were carried out, verifying that the proposed filtering antenna maintains these desirable properties even when mounted in close proximity to the human body at different positions. The stable impedance performance and the simultaneous wide axial ratio and radiated power beam widths make it an ideal candidate as a wearable antenna for off-body communications. The additional integrated filtering functionality further improves utility by greatly reducing interference and crosstalk with other existing wireless systems. PMID:26186795

  11. An adaptive filter bank for motor imagery based Brain Computer Interface.

    PubMed

    Thomas, Kavitha P; Guan, Cuntai; Tong, Lau Chiew; Prasad, Vinod A

    2008-01-01

    Brain Computer Interface (BCI) provides an alternative communication and control method for people with severe motor disabilities. Motor imagery patterns are widely used in Electroencephalogram (EEG) based BCIs. These motor imagery activities are associated with variation in alpha and beta band power of EEG signals called Event Related Desynchronization/synchronization (ERD/ERS). The dominant frequency bands are subject-specific and therefore performance of motor imagery based BCIs are sensitive to both temporal filtering and spatial filtering. As the optimum filter is strongly subject-dependent, we propose a method that selects the subject-specific discriminative frequency components using time-frequency plots of Fisher ratio of two-class motor imagery patterns. We also propose a low complexity adaptive Finite Impulse Response (FIR) filter bank system based on coefficient decimation technique which can realize the subject-specific bandpass filters adaptively depending on the information of Fisher ratio map. Features are extracted only from the selected frequency components. The proposed adaptive filter bank based system offers average classification accuracy of about 90%, which is slightly better than the existing fixed filter bank system. PMID:19162856

  12. Cordierite silicon nitride filters

    SciTech Connect

    Sawyer, J.; Buchan, B. ); Duiven, R.; Berger, M. ); Cleveland, J.; Ferri, J. )

    1992-02-01

    The objective of this project was to develop a silicon nitride based crossflow filter. This report summarizes the findings and results of the project. The project was phased with Phase I consisting of filter material development and crossflow filter design. Phase II involved filter manufacturing, filter testing under simulated conditions and reporting the results. In Phase I, Cordierite Silicon Nitride (CSN) was developed and tested for permeability and strength. Target values for each of these parameters were established early in the program. The values were met by the material development effort in Phase I. The crossflow filter design effort proceeded by developing a macroscopic design based on required surface area and estimated stresses. Then the thermal and pressure stresses were estimated using finite element analysis. In Phase II of this program, the filter manufacturing technique was developed, and the manufactured filters were tested. The technique developed involved press-bonding extruded tiles to form a filter, producing a monolithic filter after sintering. Filters manufactured using this technique were tested at Acurex and at the Westinghouse Science and Technology Center. The filters did not delaminate during testing and operated and high collection efficiency and good cleanability. Further development in areas of sintering and filter design is recommended.

  13. Bag filters for TPP

    SciTech Connect

    L.V. Chekalov; Yu.I. Gromov; V.V. Chekalov

    2007-05-15

    Cleaning of TPP flue gases with bag filters capable of pulsed regeneration is examined. A new filtering element with a three-dimensional filtering material formed from a needle-broached cloth in which the filtration area, as compared with a conventional smooth bag, is increased by more than two times, is proposed. The design of a new FRMI type of modular filter is also proposed. A standard series of FRMI filters with a filtration area ranging from 800 to 16,000 m{sup 2} is designed for an output more than 1 million m{sub 3}/h of with respect to cleaned gas. The new bag filter permits dry collection of sulfur oxides from waste gases at TPP operating on high-sulfur coals. The design of the filter makes it possible to replace filter elements without taking the entire unit out of service.

  14. HEPA filter monitoring program

    NASA Astrophysics Data System (ADS)

    Kirchner, K. N.; Johnson, C. M.; Aiken, W. F.; Lucerna, J. J.; Barnett, R. L.; Jensen, R. T.

    1986-07-01

    The testing and replacement of HEPA filters, widely used in the nuclear industry to purify process air, are costly and labor-intensive. Current methods of testing filter performance, such as differential pressure measurement and scanning air monitoring, allow determination of overall filter performance but preclude detection of incipient filter failure such as small holes in the filters. Using current technology, a continual in-situ monitoring system was designed which provides three major improvements over current methods of filter testing and replacement. The improvements include: cost savings by reducing the number of intact filters which are currently being replaced unnecessarily; more accurate and quantitative measurement of filter performance; and reduced personnel exposure to a radioactive environment by automatically performing most testing operations.

  15. Novel Backup Filter Device for Candle Filters

    SciTech Connect

    Bishop, B.; Goldsmith, R.; Dunham, G.; Henderson, A.

    2002-09-18

    The currently preferred means of particulate removal from process or combustion gas generated by advanced coal-based power production processes is filtration with candle filters. However, candle filters have not shown the requisite reliability to be commercially viable for hot gas clean up for either integrated gasifier combined cycle (IGCC) or pressurized fluid bed combustion (PFBC) processes. Even a single candle failure can lead to unacceptable ash breakthrough, which can result in (a) damage to highly sensitive and expensive downstream equipment, (b) unacceptably low system on-stream factor, and (c) unplanned outages. The U.S. Department of Energy (DOE) has recognized the need to have fail-safe devices installed within or downstream from candle filters. In addition to CeraMem, DOE has contracted with Siemens-Westinghouse, the Energy & Environmental Research Center (EERC) at the University of North Dakota, and the Southern Research Institute (SRI) to develop novel fail-safe devices. Siemens-Westinghouse is evaluating honeycomb-based filter devices on the clean-side of the candle filter that can operate up to 870 C. The EERC is developing a highly porous ceramic disk with a sticky yet temperature-stable coating that will trap dust in the event of filter failure. SRI is developing the Full-Flow Mechanical Safeguard Device that provides a positive seal for the candle filter. Operation of the SRI device is triggered by the higher-than-normal gas flow from a broken candle. The CeraMem approach is similar to that of Siemens-Westinghouse and involves the development of honeycomb-based filters that operate on the clean-side of a candle filter. The overall objective of this project is to fabricate and test silicon carbide-based honeycomb failsafe filters for protection of downstream equipment in advanced coal conversion processes. The fail-safe filter, installed directly downstream of a candle filter, should have the capability for stopping essentially all particulate

  16. MST Filterability Tests

    SciTech Connect

    Poirier, M. R.; Burket, P. R.; Duignan, M. R.

    2015-03-12

    The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). The low filter flux through the ARP has limited the rate at which radioactive liquid waste can be treated. Recent filter flux has averaged approximately 5 gallons per minute (gpm). Salt Batch 6 has had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. In addition, at the time the testing started, SRR was assessing the impact of replacing the 0.1 micron filter with a 0.5 micron filter. This report describes testing of MST filterability to investigate the impact of filter pore size and MST particle size on filter flux and testing of filter enhancers to attempt to increase filter flux. The authors constructed a laboratory-scale crossflow filter apparatus with two crossflow filters operating in parallel. One filter was a 0.1 micron Mott sintered SS filter and the other was a 0.5 micron Mott sintered SS filter. The authors also constructed a dead-end filtration apparatus to conduct screening tests with potential filter aids and body feeds, referred to as filter enhancers. The original baseline for ARP was 5.6 M sodium salt solution with a free hydroxide concentration of approximately 1.7 M.3 ARP has been operating with a sodium concentration of approximately 6.4 M and a free hydroxide concentration of approximately 2.5 M. SRNL conducted tests varying the concentration of sodium and free hydroxide to determine whether those changes had a significant effect on filter flux. The feed slurries for the MST filterability tests were composed of simple salts (NaOH, NaNO2, and NaNO3) and MST (0.2 – 4.8 g/L). The feed slurry for the filter enhancer tests contained simulated salt batch 6 supernate, MST, and filter enhancers.

  17. Survey of digital filtering

    NASA Technical Reports Server (NTRS)

    Nagle, H. T., Jr.

    1972-01-01

    A three part survey is made of the state-of-the-art in digital filtering. Part one presents background material including sampled data transformations and the discrete Fourier transform. Part two, digital filter theory, gives an in-depth coverage of filter categories, transfer function synthesis, quantization and other nonlinear errors, filter structures and computer aided design. Part three presents hardware mechanization techniques. Implementations by general purpose, mini-, and special-purpose computers are presented.

  18. Nonlinear optimal semirecursive filtering

    NASA Astrophysics Data System (ADS)

    Daum, Frederick E.

    1996-05-01

    This paper describes a new hybrid approach to filtering, in which part of the filter is recursive but another part in non-recursive. The practical utility of this notion is to reduce computational complexity. In particular, if the non- recursive part of the filter is sufficiently small, then such a filter might be cost-effective to run in real-time with computer technology available now or in the future.

  19. Chua's circuit and its characterization as a filter

    NASA Astrophysics Data System (ADS)

    Campos-Cantón, I.; Segura-Cisneros, O. A.; Balderas-Navarro, R. E.; Campos-Cantón, E.

    2014-11-01

    This article deals with Chua's circuit characterization from the point of view of a filter based on the concept of piecewise linear functions. Furthermore, experiments are developed for teaching electronic systems that can be used for novel filtering concepts. The frequency range in which they are tested is from 20 Hz to 20 kHz, due to the audio spectrum comprised in this frequency range. The node associated with the capacitor and Chua's diode is used as input, and the node for another capacitor and the coil is used as output, thereby establishing one input-output relationship for each system case given by the piecewise linear functions. The experimental result shows that Chua's circuit behaves as a bandpass filter-amplifier, with a maximum frequency around 3 kHz and bandwidth between 1.5 kHz and 5.5 kHz. The results presented in this paper can motivate engineering students to pursue applications of novel electrical circuits based on topics that are of potential interest in their future research studies.

  20. Flight Performance of UV Filters on the ALEXIS Satellite

    SciTech Connect

    Bloch, J.J.; Roussel-Dupre, D.; Starin, S.

    1999-07-08

    The ALEXIS (Array of Low-Energy X-ray Imaging Sensors) mission, serving as the first dedicated all-sky monitor in the extreme UV, has been collecting data since its launch in 1993. ALEXIS operates in a 70{degree} inclination orbit at an altitude of 800 km. The ALEXIS science mission is to observe the cosmic UV background and to study variability of EUV sources. The ALEXIS experiment is composed of six telescopes. Although the telescopes were only designed for a one-year technology verification mission, they are still functioning with much the same effectiveness as at the beginning of the mission. The telescopes comprise: (1) layered synthetic microstructure (LSM) spherical mirrors, (2) thin foil filters, and (3) microchannel plate (MCP) detectors, all enshrouded within the telescope body. The LSM mirrors select the bandpass for each telescope, while rejecting some of the HeII 304{angstrom} geocoronal radiation. The filters, constructed either from aluminum/carbon or Lexan/titanium/boron, serve to strongly reject the geocoronal radiation, as well as longer wavelength emission from bright OB stars. Each telescope detector consists of two plates, the outermost of which is curved to accurately match the spherical focal surface of the mirror. By reviewing the ground and flight histories, this paper analyzes the flight performance of the filters, including the effects of long term exposure and the formation of pinholes.

  1. Combined tunable filters based swept laser source for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Chen, Minghui; Ding, Zhihua; Wang, Cheng; Huang, Yimei; Chen, Rong; Song, Chengli

    2013-03-01

    We demonstrate a novel ultra-broad tunable bandwidth and narrow instantaneous line-width swept laser source using combined tunable filters working at 1290 nm center wavelength for application in optical coherence tomography. The combined filters consist of a fiber Fabry-Perot tunable filter (FFP-TF) and a polygon mirror with scanning grating based filter. The FFP-TF has the narrow free spectral range (FSR) but ultra-high spectral resolution (narrow instantaneous bandwidth) driven at high frequency far from resonant frequency. The polygon filter in the Littrow configuration is composed of fiber collimator, polygon mirror driven by function generator, and diffractive grating with low groove. Polygon filter coarsely tunes with wide turning range and then FFP-TF finely tunes with narrow band-pass filtering. In contrast to traditional method using single tunable filter, the trade-off between bandwidth and instantaneous line-width is alleviated. The combined filters can realize ultra wide scan range and fairly narrow instantaneous bandwidth simultaneously. Two semiconductor optical amplifiers (SOA) in the parallel manner are used as the gain medium. The wide bandwidth could be obtained by these parallel SOAs to be suitable for sufficient wide range of the polygon filter's FSR because each SOA generates its own spectrum independently. The proposed swept laser source provides an edge-to-edge scanning range of 180 nm covering 1220 to 1400 nm with instantaneous line-width of about 0.03 nm at sweeping rate of 23.3 kHz. The swept laser source with combined filters offers broadband tunable range with narrow instantaneous line-width, which especially benefits for high resolution and deep imaging depth optical frequency domain imaging.

  2. The ribosome filter redux.

    PubMed

    Mauro, Vincent P; Edelman, Gerald M

    2007-09-15

    The ribosome filter hypothesis postulates that ribosomes are not simply translation machines but also function as regulatory elements that differentially affect or filter the translation of particular mRNAs. On the basis of new information, we take the opportunity here to review the ribosome filter hypothesis, suggest specific mechanisms of action, and discuss recent examples from the literature that support it. PMID:17890902

  3. Filter service system

    DOEpatents

    Sellers, Cheryl L.; Nordyke, Daniel S.; Crandell, Richard A.; Tomlins, Gregory; Fei, Dong; Panov, Alexander; Lane, William H.; Habeger, Craig F.

    2008-12-09

    According to an exemplary embodiment of the present disclosure, a system for removing matter from a filtering device includes a gas pressurization assembly. An element of the assembly is removably attachable to a first orifice of the filtering device. The system also includes a vacuum source fluidly connected to a second orifice of the filtering device.

  4. HEPA filter encapsulation

    DOEpatents

    Gates-Anderson, Dianne D.; Kidd, Scott D.; Bowers, John S.; Attebery, Ronald W.

    2003-01-01

    A low viscosity resin is delivered into a spent HEPA filter or other waste. The resin is introduced into the filter or other waste using a vacuum to assist in the mass transfer of the resin through the filter media or other waste.

  5. Nonlinear Attitude Filtering Methods

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Crassidis, John L.; Cheng, Yang

    2005-01-01

    This paper provides a survey of modern nonlinear filtering methods for attitude estimation. Early applications relied mostly on the extended Kalman filter for attitude estimation. Since these applications, several new approaches have been developed that have proven to be superior to the extended Kalman filter. Several of these approaches maintain the basic structure of the extended Kalman filter, but employ various modifications in order to provide better convergence or improve other performance characteristics. Examples of such approaches include: filter QUEST, extended QUEST, the super-iterated extended Kalman filter, the interlaced extended Kalman filter, and the second-order Kalman filter. Filters that propagate and update a discrete set of sigma points rather than using linearized equations for the mean and covariance are also reviewed. A two-step approach is discussed with a first-step state that linearizes the measurement model and an iterative second step to recover the desired attitude states. These approaches are all based on the Gaussian assumption that the probability density function is adequately specified by its mean and covariance. Other approaches that do not require this assumption are reviewed, including particle filters and a Bayesian filter based on a non-Gaussian, finite-parameter probability density function on SO(3). Finally, the predictive filter, nonlinear observers and adaptive approaches are shown. The strengths and weaknesses of the various approaches are discussed.

  6. Practical Active Capacitor Filter

    NASA Technical Reports Server (NTRS)

    Shuler, Robert L., Jr. (Inventor)

    2005-01-01

    A method and apparatus is described that filters an electrical signal. The filtering uses a capacitor multiplier circuit where the capacitor multiplier circuit uses at least one amplifier circuit and at least one capacitor. A filtered electrical signal results from a direct connection from an output of the at least one amplifier circuit.

  7. A New Ground Motion Intensity Measure, Peak Filtered Acceleration (PFA), to Estimate Collapse Vulnerability of Buildings in Earthquakes

    NASA Astrophysics Data System (ADS)

    Song, Shiyan

    In this thesis, we develop an efficient collapse prediction model, the PFA (Peak Filtered Acceleration) model, for buildings subjected to different types of ground motions. For the structural system, the PFA model covers modern steel and reinforced concrete moment-resisting frame buildings (potentially reinforced concrete shear wall buildings). For ground motions, the PFA model covers ramp-pulse-like ground motions, long-period ground motions, and short-period ground motions. To predict whether a building will collapse in response to a given ground motion, we first extract long-period components from the ground motion using a Butterworth low-pass filter with suggested order and cutoff frequency. The order depends on the type of ground motion, and the cutoff frequency depends on the building's natural frequency and ductility. We then compare the filtered acceleration time history with the capacity of the building. The capacity of the building is a constant for 2-dimentional buildings and a limit domain for 3-dimentional buildings. If the filtered acceleration exceeds the building's capacity, the building is predicted to collapse. Otherwise, it is expected to survive the ground motion. The parameters used in PFA model, which include fundamental period, global ductility and lateral capacity, can be obtained either from numerical analysis or interpolation based on the reference building system proposed in this thesis. The PFA collapse prediction model greatly reduces computational complexity while archiving good accuracy. It is verified by FEM simulations of 13 frame building models and 150 ground motion records. Based on the developed collapse prediction model, we propose to use PFA (Peak Filtered Acceleration) as a new ground motion intensity measure for collapse prediction. We compare PFA with traditional intensity measures PGA, PGV, PGD, and Sa in collapse prediction and find that PFA has the best performance among all the intensity measures. We also provide a

  8. Regenerative particulate filter development

    NASA Technical Reports Server (NTRS)

    Descamp, V. A.; Boex, M. W.; Hussey, M. W.; Larson, T. P.

    1972-01-01

    Development, design, and fabrication of a prototype filter regeneration unit for regenerating clean fluid particle filter elements by using a backflush/jet impingement technique are reported. Development tests were also conducted on a vortex particle separator designed for use in zero gravity environment. A maintainable filter was designed, fabricated and tested that allows filter element replacement without any leakage or spillage of system fluid. Also described are spacecraft fluid system design and filter maintenance techniques with respect to inflight maintenance for the space shuttle and space station.

  9. Ceramic fiber filter technology

    SciTech Connect

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  10. Plasma Treatment to Remove Carbon from Indium UV Filters

    NASA Technical Reports Server (NTRS)

    Greer, Harold F.; Nikzad, Shouleh; Beasley, Matthew; Gantner, Brennan

    2012-01-01

    The sounding rocket experiment FIRE (Far-ultraviolet Imaging Rocket Experiment) will improve the science community fs ability to image a spectral region hitherto unexplored astronomically. The imaging band of FIRE (.900 to 1,100 Angstroms) will help fill the current wavelength imaging observation hole existing from approximately equal to 620 Angstroms to the GALEX band near 1,350 Angstroms. FIRE is a single-optic prime focus telescope with a 1.75-m focal length. The bandpass of 900 to 1100 Angstroms is set by a combination of the mirror coating, the indium filter in front of the detector, and the salt coating on the front of the detector fs microchannel plates. Critical to this is the indium filter that must reduce the flux from Lymanalpha at 1,216 Angstroms by a minimum factor of 10(exp -4). The cost of this Lyman-alpha removal is that the filter is not fully transparent at the desired wavelengths of 900 to 1,100 Angstroms. Recently, in a project to improve the performance of optical and solar blind detectors, JPL developed a plasma process capable of removing carbon contamination from indium metal. In this work, a low-power, low-temperature hydrogen plasma reacts with the carbon contaminants in the indium to form methane, but leaves the indium metal surface undisturbed. This process was recently tested in a proof-of-concept experiment with a filter provided by the University of Colorado. This initial test on a test filter showed improvement in transmission from 7 to 9 percent near 900 with no process optimization applied. Further improvements in this performance were readily achieved to bring the total transmission to 12% with optimization to JPL's existing process.

  11. Compact planar microwave blocking filters

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)

    2012-01-01

    A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.

  12. Optical Filters to Exclude Non-Doppler-Shifted Light in Fast Velocimetry

    SciTech Connect

    Goosman, D; Avara, G; Wade, J; Rivera, A

    2002-08-22

    We frequently measure velocity-time histories of dynamic experiments. In some, the Doppler-shifted light is often weak compared to non-shifted light reflected from stationary surfaces and imperfections in components. With our Fabry-Perot (FP) based systems which handle multiple frequencies, data is lost where the fringes coincide; if we had used an intensity-measuring VISAR system, it would probably fail. We designed a facility for doing experiments under such conditions by selectively eliminating most of the non-shifted light. Our first filter excluded non-shifted light by a factor of 300 when manually tuned, and by 150 when run in an auto-tuning mode. It used a single 50 mm diameter FP as the filter with a spacing of 1.65 mm and reflectivities of 77%, and filters five channels prior to use in one of our 5-beam velocimeters. One use of the filter system was to embed optical fibers in long sections of explosives to make continuous detonation velocity-time histories. We have carried out many such tests with this filter, and two without. A special single-beam filter was constructed with a 40% efficiency for shifted light that rejected non-shifted light by 4 million times, with a bandpass of a few GHz.

  13. Multifrequency spatial filtering: A general property of two-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Serebryannikov, A. E.; Colak, E.; Petrov, A.; Usik, P. V.; Ozbay, E.

    2016-01-01

    Spatial filtering, an analog of frequency-domain filtering that can be obtained in the incidence angle domain at a fixed frequency is studied in the transmission mode for slabs of two-dimensional rod-type photonic crystals. In the present paper, the emphasis is put on the demonstration of the possibility to obtain various regimes of spatial filtering, i.e., band-stop, band-pass, and low-pass filtering in different frequency ranges in one simple configuration. The operation is based on the use of several Floquet-Bloch modes with appropriate dispersion properties, so that such one or two co-existing mode(s) contribute to the forming of a proper filter characteristic within each specific frequency range. It is shown that high-efficiency transmission and steep switching between pass and stop bands can be obtained in the angle domain for wide ranges of variation of the problem parameters. In particular, by varying the rod-diameter-to-lattice-constant ratio, one attains lots of freedom in the engineering of spatial filters with desired transmission characteristics.

  14. Accounting for filter bandwidth improves the quantitative accuracy of bioluminescence tomography

    NASA Astrophysics Data System (ADS)

    Taylor, Shelley L.; Mason, Suzannah K. G.; Glinton, Sophie L.; Cobbold, Mark; Dehghani, Hamid

    2015-09-01

    Bioluminescence imaging is a noninvasive technique whereby surface weighted images of luminescent probes within animals are used to characterize cell count and function. Traditionally, data are collected over the entire emission spectrum of the source using no filters and are used to evaluate cell count/function over the entire spectrum. Alternatively, multispectral data over several wavelengths can be incorporated to perform tomographic reconstruction of source location and intensity. However, bandpass filters used for multispectral data acquisition have a specific bandwidth, which is ignored in the reconstruction. In this work, ignoring the bandwidth is shown to introduce a dependence of the recovered source intensity on the bandwidth of the filters. A method of accounting for the bandwidth of filters used during multispectral data acquisition is presented and its efficacy in increasing the quantitative accuracy of bioluminescence tomography is demonstrated through simulation and experiment. It is demonstrated that while using filters with a large bandwidth can dramatically decrease the data acquisition time, if not accounted for, errors of up to 200% in quantitative accuracy are introduced in two-dimensional planar imaging, even after normalization. For tomographic imaging, the use of this method to account for filter bandwidth dramatically improves the quantitative accuracy.

  15. Vibration control of a flexible beam driven by a ball-screw stage with adaptive notch filters and a line enhancer

    NASA Astrophysics Data System (ADS)

    Wu, Shang-Teh; Lian, Sing-Han; Chen, Sheng-Han

    2015-07-01

    For a low-stiffness beam driven by a ball-screw stage, the lateral vibrations cannot be adequately controlled by a collocated compensator based on rotary-encoder feedback alone. Acceleration signals at the tip of the flexible beam are measured for active vibration control in addition to the collocated compensator. A second-order bandpass filter (a line enhancer) and two notch filters are included in the acceleration-feedback loop to raise modal dampings for the first and the second flexible modes without exciting higher-frequency resonances. A novel adaptation algorithm is devised to tune the center frequencies of the notch filters in real time. It consists of a second-order low-pass filter, a second-order bandpass filter and a phase detector. Improvement of the control system is elaborated progressively with the root-locus and bode-plot analyses, along with a physical interpretation. Extensive testings are conducted on an experimental device to verify the effectiveness of the control method.

  16. Fabric filter blinding mechanisms

    SciTech Connect

    Notestein, J.E.; Shang, J.Y.

    1982-08-01

    This discussion of various bag/cloth filter degradation mechanisms is mostly common sense. However, this information is occasionally lost in the subtleties of real-system operation. Although this paper is written with reference to fluidized-bed combustion (FBC) applications, the insights are generally applicable. For enumeration of particular filter fabric and baghouse experiences in FBC applications, the reader is referred to a report by Davy McKee Corporatin (no date). A fabric filter is a composite matrix of fibers oriented to retain the dust particles from dust-laden gas. The cleaned gas passes through the fabric filter; the retained dust particles are deposited on the surface of (and within) the fiber matrix. The retained dust can be later removed through mechanical means. The fabric may be made of any fibrous material, spun in yarn, and then woven, impacted, needled, or bonded into a felt. Deep penetration of aggregated fine particles, lack of dust removal during filter cleaning, and chars or condensed aerosols may contribute to the increase in pressure drop across the filter. This increases the filter operation power consumption and, consequently, reduces the filtration capacity. The phenomenon of building a high-pressure drop in spite of filter cleaning provisions is known as blinding. In order to maintain an acceptable gas throughput, blinding problems must be addressed. Recommendations are given: maintain temperature above dew point, use filter aids, by-pass filter during start-up or operational upsets, etc.

  17. Filtering separators having filter cleaning apparatus

    SciTech Connect

    Margraf, A.

    1984-08-28

    This invention relates to filtering separators of the kind having a housing which is subdivided by a partition, provided with parallel rows of holes or slots, into a dust-laden gas space for receiving filter elements positioned in parallel rows and being impinged upon by dust-laden gas from the outside towards the inside, and a clean gas space. In addition, the housing is provided with a chamber for cleansing the filter element surfaces of a row by counterflow action while covering at the same time the partition holes or slots leading to the adjacent rows of filter elements. The chamber is arranged for the supply of compressed air to at least one injector arranged to feed compressed air and secondary air to the row of filter elements to be cleansed. The chamber is also reciprocatingly displaceable along the partition in periodic and intermittent manner. According to the invention, a surface of the chamber facing towards the partition covers at least two of the rows of holes or slots of the partition, and the chamber is closed upon itself with respect to the clean gas space, and is connected to a compressed air reservoir via a distributor pipe and a control valve. At least one of the rows of holes or slots of the partition and the respective row of filter elements in flow communication therewith are in flow communication with the discharge side of at least one injector acted upon with compressed air. At least one other row of the rows of holes or slots of the partition and the respective row of filter elements is in flow communication with the suction side of the injector.

  18. Determination of 90Sr in contaminated environmental samples by tuneable bandpass dynamic reaction cell ICP-MS.

    PubMed

    Taylor, V F; Evans, R D; Cornett, R J

    2007-01-01

    A rapid method for the extraction and determination of 90Sr in natural water, plant and sediment samples was developed using extraction chromatography and dynamic reaction cell ICP-MS, with O2 as a reaction gas. While isobaric interference from the stable isotope 90Zr was efficiently removed by this method, interferences produced from in-cell reactions with Fe+ and Ni+ required suppression by tuneable bandpass, and in sediments, additional chromatographic separation. Method detection limits were 0.1 pg g-1 (0.5 Bq g-1), 0.04 pg g-1(0.2 Bq g-1), and 3 pg L-1 (5 Bq L-1) for sediments, plant and water samples, respectively, and 90Sr concentrations determined by ICP-MS were in good agreement with activities determined by Cerenkov counting and with certified reference values. While mass spectrometric determination does not rival detection limits achievable by radiometric counting, radiometric determination of 90Sr, a pure beta-emitter, is hindered by long analysis times (several weeks); the comparatively fast analysis achieved via ICP-MS enables same-day preparation and analysis of samples, making this an important technique for the environmental monitoring of areas contaminated by radioactivity. PMID:17111103

  19. Wavelength filtering and demultiplexing devices based on ultrathin corrugated MIM waveguides

    NASA Astrophysics Data System (ADS)

    Yang, Bao Jia; Zhou, Yong Jin

    2016-05-01

    We have numerically investigated the transmission properties of spoof surface plasmon polaritons on the ultrathin corrugated metal-insulator-metal (MIM) waveguides with different grooves. A band-pass plasmonic filter with T-shaped grooves and a compact 4-way wavelength division demultiplexing (WDM) incorporating the filter have been proposed. The whole 4-way WDM is more compact by the use of corrugated MIM waveguides with meander grooves. The near electric field distributions show that electromagnetic waves at different frequencies are guided and propagate along different branches with good isolation between branches. The experimental and numerical results have shown good agreements and validated the functions of the 4-way wavelength splitter. We also numerically investigate the 4-way WDM at terahertz frequencies by scaling down the whole structure. It is believed that the spoof plasmonic devices can find more applications in the plasmonic integration platform, such as optical communications, signal processing and spectral engineering.

  20. Metal-dielectric filters for solar-blind silicon ultraviolet detectors.

    PubMed

    Hennessy, John; Jewell, April D; Hoenk, Michael E; Nikzad, Shouleh

    2015-04-10

    We report on the fabrication of metal-dielectric thin film stacks deposited directly onto silicon substrates for use as ultraviolet bandpass filters. Integration of these filters onto silicon improves the admittance matching of the structure when compared to similar designs fabricated on transparent substrates, leading to higher peak transmission or improved out-of-band rejection if used with a Si-based sensor platform. Test structures fabricated with metallic Al and atomic layer deposited Al2O3 were characterized with spectroscopic ellipsometry and agree well with optical models. These models predict transmission as high as 90% the spectral range of 200-300 nm for simple three-layer coatings. PMID:25967344

  1. Denoising preterm EEG by signal decomposition and adaptive filtering: a comparative study.

    PubMed

    Navarro, X; Porée, F; Beuchée, A; Carrault, G

    2015-03-01

    Electroencephalography (EEG) from preterm infant monitoring systems is usually contaminated by several sources of noise that have to be removed in order to correctly interpret signals and perform automated analysis reliably. Band-pass and adaptive filters (AF) continue to be systematically applied, but their efficacy may be decreased facing preterm EEG patterns such as the tracé alternant and slow delta-waves. In this paper, we propose the combination of EEG decomposition with AF to improve the overall denoising process. Using artificially contaminated signals from real EEGs, we compared the quality of filtered signals applying different decomposition techniques: the discrete wavelet transform, the empirical mode decomposition (EMD) and a recent improved version, the complete ensemble EMD with adaptive noise. Simulations demonstrate that introducing EMD-based techniques prior to AF can reduce up to 30% the root mean squared errors in denoised EEGs. PMID:25659233

  2. Surface-acoustic-wave filter with a center frequency of 960 MHz

    NASA Astrophysics Data System (ADS)

    Guliaev, Iu. V.; Fedorets, V. N.; Buliuk, A. N.

    1985-05-01

    The paper reports the experimental characteristics of a SAW bandpass filter operating at the third harmonic with a center frequency of 960 MHz. The filter, fabricated by optical lithography, has a passband of 7 MHz at the 3 dB level; the insertion loss is 15 dB; the sidelobe suppression is at least 43 dB; the shape factor of the amplitude-frequency response curve at the 3 and 40 dB levels is 2.6; and the nonuniformity of this curve in the passband is 0.6 dB. Experimental results indicate that SAW absorption in the metal films from which the electrodes and the electrostatic shield between converters are fabricated must be taken into account in the design of devices for the microwave range.

  3. Sequentially timed all-optical mapping photography (STAMP) utilizing spectral filtering.

    PubMed

    Suzuki, Takakazu; Isa, Fumihiro; Fujii, Leo; Hirosawa, Kenichi; Nakagawa, Keiichi; Goda, Keisuke; Sakuma, Ichiro; Kannari, Fumihiko

    2015-11-16

    We propose and experimentally demonstrate a new method called SF-STAMP for sequentially timed all-optical mapping photography (STAMP) that utilizes spectral filtering. SF-STAMP is composed of a diffractive optical element (DOE), a band-pass filter, and two Fourier transform lenses. Using a linearly frequency-chirped pulse and converting the wavelength to the time axis, we realize single-shot ultrafast burst imaging. As an experimental demonstration of SF-STAMP, we monitor the dynamics of a laser ablation using a linearly frequency-chirped broadband pulse (>100 nm) that is temporally stretched up to ~40 ps. This imaging method is expected to be effective for investigating ultrafast dynamics in a diverse range of fields, such as photochemistry, plasma physics, and fluidics. PMID:26698529

  4. Optical Metrology for the Filter Set for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.; Boucarut, Rene A.; Content, David A.; Keski-Kuha, Ritva A.; Krebs, Carolyn A.; Miner, Linda A.; Norton, Todd A.; Mehalick, Kimberly; Petrone, Peter; Bush, Frank D.; Puc, Bernard; Standley, Clive; Tsvetanov, Zlatan; Kral, Catherine

    1998-01-01

    The Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) will employ a wide variety of spectral filtration components including narrow band, medium band, wide band, and far ultraviolet (FUV) long pass filters, spatially- variable filters (ramp filters), VIS/IR polarizers, NUV polarizers, FUV prisms, and a grism. These components are spread across ACS's Wide Field, High Resolution, and Solar Blind channels which provide diffraction-limited imaging of astronomical targets using aberration-correcting optics which remove most aberrations from HST's Optical Telescope Assembly (OTA). In order for ACS to be truly advanced, these filters must push the state-of-the-art in performance in a number of key areas at the same time. Important requirements which these filters must meet include outstanding transmitted wavefront, high transmittance, uniform transmittance across each filter, spectrally structure-free bandpasses, exceptionally high out of band rejection, and a high degree of parfocality. These constitute a very stringent set of requirements indeed, especially for filters which are up to 90 mm in diameter. The development of optical metrology stations used to demonstrate that each ACS filter will meet its design specifications is discussed. Of particular note are specially-designed spectral transmissometers and interferometers.

  5. The application of digital signal processing techniques to a teleoperator radar system

    NASA Technical Reports Server (NTRS)

    Pujol, A.

    1982-01-01

    A digital signal processing system was studied for the determination of the spectral frequency distribution of echo signals from a teleoperator radar system. The system consisted of a sample and hold circuit, an analog to digital converter, a digital filter, and a Fast Fourier Transform. The system is interfaced to a 16 bit microprocessor. The microprocessor is programmed to control the complete digital signal processing. The digital filtering and Fast Fourier Transform functions are implemented by a S2815 digital filter/utility peripheral chip and a S2814A Fast Fourier Transform chip. The S2815 initially simulates a low-pass Butterworth filter with later expansion to complete filter circuit (bandpass and highpass) synthesizing.

  6. Generic Kalman Filter Software

    NASA Technical Reports Server (NTRS)

    Lisano, Michael E., II; Crues, Edwin Z.

    2005-01-01

    The Generic Kalman Filter (GKF) software provides a standard basis for the development of application-specific Kalman-filter programs. Historically, Kalman filters have been implemented by customized programs that must be written, coded, and debugged anew for each unique application, then tested and tuned with simulated or actual measurement data. Total development times for typical Kalman-filter application programs have ranged from months to weeks. The GKF software can simplify the development process and reduce the development time by eliminating the need to re-create the fundamental implementation of the Kalman filter for each new application. The GKF software is written in the ANSI C programming language. It contains a generic Kalman-filter-development directory that, in turn, contains a code for a generic Kalman filter function; more specifically, it contains a generically designed and generically coded implementation of linear, linearized, and extended Kalman filtering algorithms, including algorithms for state- and covariance-update and -propagation functions. The mathematical theory that underlies the algorithms is well known and has been reported extensively in the open technical literature. Also contained in the directory are a header file that defines generic Kalman-filter data structures and prototype functions and template versions of application-specific subfunction and calling navigation/estimation routine code and headers. Once the user has provided a calling routine and the required application-specific subfunctions, the application-specific Kalman-filter software can be compiled and executed immediately. During execution, the generic Kalman-filter function is called from a higher-level navigation or estimation routine that preprocesses measurement data and post-processes output data. The generic Kalman-filter function uses the aforementioned data structures and five implementation- specific subfunctions, which have been developed by the user on

  7. Simulation of mid-infrared clutter rejection. 1: One-dimensional LMS spatial filter and adaptive threshold algorithms.

    PubMed

    Longmire, M S; Milton, A F; Takken, E H

    1982-11-01

    Several 1-D signal processing techniques have been evaluated by simulation with a digital computer using high-spatial-resolution (0.15 mrad) noise data gathered from back-lit clouds and uniform sky with a scanning data collection system operating in the 4.0-4.8-microm spectral band. Two ordinary bandpass filters and a least-mean-square (LMS) spatial filter were evaluated in combination with a fixed or adaptive threshold algorithm. The combination of a 1-D LMS filter and a 1-D adaptive threshold sensor was shown to reject extreme cloud clutter effectively and to provide nearly equal signal detection in a clear and cluttered sky, at least in systems whose NEI (noise equivalent irradiance) exceeds 1.5 x 10(-13) W/cm(2) and whose spatial resolution is better than 0.15 x 0.36 mrad. A summary gives highlights of the work, key numerical results, and conclusions. PMID:20396326

  8. Concentric Split Flow Filter

    NASA Technical Reports Server (NTRS)

    Stapleton, Thomas J. (Inventor)

    2015-01-01

    A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

  9. Optically tunable optical filter

    NASA Astrophysics Data System (ADS)

    James, Robert T. B.; Wah, Christopher; Iizuka, Keigo; Shimotahira, Hiroshi

    1995-12-01

    We experimentally demonstrate an optically tunable optical filter that uses photorefractive barium titanate. With our filter we implement a spectrum analyzer at 632.8 nm with a resolution of 1.2 nm. We simulate a wavelength-division multiplexing system by separating two semiconductor laser diodes, at 1560 nm and 1578 nm, with the same filter. The filter has a bandwidth of 6.9 nm. We also use the same filter to take 2.5-nm-wide slices out of a 20-nm-wide superluminescent diode centered at 840 nm. As a result, we experimentally demonstrate a phenomenal tuning range from 632.8 to 1578 nm with a single filtering device.

  10. Contactor/filter improvements

    DOEpatents

    Stelman, D.

    1988-06-30

    A contactor/filter arrangement for removing particulate contaminants from a gaseous stream is described. The filter includes a housing having a substantially vertically oriented granular material retention member with upstream and downstream faces, a substantially vertically oriented microporous gas filter element, wherein the retention member and the filter element are spaced apart to provide a zone for the passage of granular material therethrough. A gaseous stream containing particulate contaminants passes through the gas inlet means as well as through the upstream face of the granular material retention member, passing through the retention member, the body of granular material, the microporous gas filter element, exiting out of the gas outlet means. A cover screen isolates the filter element from contact with the moving granular bed. In one embodiment, the granular material is comprised of porous alumina impregnated with CuO, with the cover screen cleaned by the action of the moving granular material as well as by backflow pressure pulses. 6 figs.

  11. Detection of micro-cracks on metal surfaces using near-field microwave dual-behavior resonator filters

    NASA Astrophysics Data System (ADS)

    Kerouedan, Julien; Quéffélec, Patrick; Talbot, Philippe; Quendo, Cédric; DeBlasi, Serge; LeBrun, Alain

    2008-10-01

    This paper demonstrates how micro-cracks at the surface of metals can be detected and imaged by near-field microwave techniques from the crack-induced variations of the resonance frequency and of the resonant circuit quality factor. It deals with two resonant sensors: a quarter wavelength microstrip line resonator terminated by an electric dipole and an original dual-behavior resonator (DBR) band-pass filter probe. The detection principle is developed, at first, from the use of the electric dipole probe. The low sensitivity of the electric dipole resonator led us to investigate whether first-order band-pass filters based on dual behavior resonators were able to detect a 200 µm wide and 3 mm deep rectangular EDM notch at the surface of a steel plate used to validate our method. Simulation data and measurements results carried out on a stainless steel mock-up with several 200 µm wide EDM rectangular notches showed that the DBR sensor is more sensitive than the electric dipole probe, and highlighted the link between the spatial resolution and the width of the high-frequency stub of the DBR filter. Moreover, we demonstrate the notch detection for any orientation of the defect in relation to the DBR sensor and the ability to differentiate between notches of different depths. Simulation data and measurement results are presented and discussed.

  12. Hybrid Filter Membrane

    NASA Technical Reports Server (NTRS)

    Laicer, Castro; Rasimick, Brian; Green, Zachary

    2012-01-01

    Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

  13. Filter vapor trap

    DOEpatents

    Guon, Jerold

    1976-04-13

    A sintered filter trap is adapted for insertion in a gas stream of sodium vapor to condense and deposit sodium thereon. The filter is heated and operated above the melting temperature of sodium, resulting in a more efficient means to remove sodium particulates from the effluent inert gas emanating from the surface of a liquid sodium pool. Preferably the filter leaves are precoated with a natrophobic coating such as tetracosane.

  14. Westinghouse filter update

    SciTech Connect

    Bruck, G.J.; Smeltzer, E.E.; Newby, R.A.; Bachovchin, D.M.

    1993-06-01

    The Department of Energy, Morgantown Energy Technology Center (DOE/METC), with Westinghouse are developing high temperature particulate filters for application in integrated, coal gasification combined cycle (IGCC) and pressurized fluidized bed combustion (PFBC) power generation systems. Development of these IGCC and PFBC advanced power cycles using subpilot and pilot scale facilities include the integrated operation of a high temperature particulate filter. This testing provides the basis for evaluating filter design, performance and operation characteristics in the actual process gas environment. This operating data is essential for the specification of components and materials and successful scaleup of the filter systems for demonstration and commercial application.

  15. Independent task Fourier filters

    NASA Astrophysics Data System (ADS)

    Caulfield, H. John

    2001-11-01

    Since the early 1960s, a major part of optical computing systems has been Fourier pattern recognition, which takes advantage of high speed filter changes to enable powerful nonlinear discrimination in `real time.' Because filter has a task quite independent of the tasks of the other filters, they can be applied and evaluated in parallel or, in a simple approach I describe, in sequence very rapidly. Thus I use the name ITFF (independent task Fourier filter). These filters can also break very complex discrimination tasks into easily handled parts, so the wonderful space invariance properties of Fourier filtering need not be sacrificed to achieve high discrimination and good generalizability even for ultracomplex discrimination problems. The training procedure proceeds sequentially, as the task for a given filter is defined a posteriori by declaring it to be the discrimination of particular members of set A from all members of set B with sufficient margin. That is, we set the threshold to achieve the desired margin and note the A members discriminated by that threshold. Discriminating those A members from all members of B becomes the task of that filter. Those A members are then removed from the set A, so no other filter will be asked to perform that already accomplished task.

  16. Filter construction and design.

    PubMed

    Jornitz, Maik W

    2006-01-01

    Sterilizing and pre-filters are manufactured in different formats and designs. The criteria for the specific designs are set by the application and the specifications of the filter user. The optimal filter unit or even system requires evaluation, such as flow rate, throughput, unspecific adsorption, steam sterilizability and chemical compatibility. These parameters are commonly tested within a qualification phase, which ensures that an optimal filter design and combination finds its use. If such design investigations are neglected it could be costly in the process scale. PMID:16570863

  17. Nanofiber Filters Eliminate Contaminants

    NASA Technical Reports Server (NTRS)

    2009-01-01

    With support from Phase I and II SBIR funding from Johnson Space Center, Argonide Corporation of Sanford, Florida tested and developed its proprietary nanofiber water filter media. Capable of removing more than 99.99 percent of dangerous particles like bacteria, viruses, and parasites, the media was incorporated into the company's commercial NanoCeram water filter, an inductee into the Space Foundation's Space Technology Hall of Fame. In addition to its drinking water filters, Argonide now produces large-scale nanofiber filters used as part of the reverse osmosis process for industrial water purification.

  18. Linear phase compressive filter

    DOEpatents

    McEwan, T.E.

    1995-06-06

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line. 2 figs.

  19. Linear phase compressive filter

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.

  20. Uneven-order decentered Shapiro filters for boundary filtering

    NASA Astrophysics Data System (ADS)

    Falissard, F.

    2015-07-01

    This paper addresses the use of Shapiro filters for boundary filtering. A new class of uneven-order decentered Shapiro filters is proposed and compared to classical Shapiro filters and even-order decentered Shapiro filters. The theoretical analysis shows that the proposed boundary filters are more accurate than the centered Shapiro filters and more robust than the even-order decentered boundary filters usable at the same distance to the boundary. The benefit of the new boundary filters is assessed for computations using the compressible Euler equations.

  1. A new technique for 100-fold increase in the FSR of optical recirculating delay line filters using a time compression unit.

    PubMed

    Nguyen, T A; Chan, E H W; Minasian, R A

    2012-10-01

    A new technique that increases the free spectral range (FSR) of a recirculating delay line filter, is presented. The concept is based on a time-compression unit, which is used in conjunction with a frequency-shifting recirculating loop that generates multi-spectral characteristics, and the idea exploits the optical wavelength domain by wavelength-to-time mapping of the taps using an oppositely time-oriented dispersive element so that the taps travel different lengths, to time compress the tap separation. This technique solves, for the first time, the long-standing problem of the small FSR limitation in recirculating microwave photonic delay line filters, opening the way to realize the main functionalities required in microwave photonic filters. Experimental results are presented which demonstrate a large 100-fold increase in the FSR of the bandpass filter response. PMID:23188320

  2. Filter holder and gasket assembly for candle or tube filters

    DOEpatents

    Lippert, T.E.; Alvin, M.A.; Bruck, G.J.; Smeltzer, E.E.

    1999-03-02

    A filter holder and gasket assembly are disclosed for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder and gasket assembly includes a filter housing, an annular spacer ring securely attached within the filter housing, a gasket sock, a top gasket, a middle gasket and a cast nut. 9 figs.

  3. Filter holder and gasket assembly for candle or tube filters

    DOEpatents

    Lippert, Thomas Edwin; Alvin, Mary Anne; Bruck, Gerald Joseph; Smeltzer, Eugene E.

    1999-03-02

    A filter holder and gasket assembly for holding a candle filter element within a hot gas cleanup system pressure vessel. The filter holder and gasket assembly includes a filter housing, an annular spacer ring securely attached within the filter housing, a gasket sock, a top gasket, a middle gasket and a cast nut.

  4. Measuring Potassium in Exoplanet Atmospheres with the OSIRIS Tunable Filter

    NASA Astrophysics Data System (ADS)

    Colón, K. D.; Deeg, H. J.; Ford, E. B.; Redfield, S.; Fortney, J. J.; Shabram, M.; Mahadevan, S.

    2013-05-01

    We report observations of the exoplanet host-star HD 80606 using the OSIRIS tunable filter imager. Very-high-precision, narrow-band photometry in four bandpasses around the K I absorption feature was acquired during the January 2010 transit of HD 80606b, with further off-transit observations taken January and April of 2010. We obtained differential photometric precisions of ~2.08×10^-4 for the in-transit flux ratio measured at 769.91 nm, which probes the K I line core. The observed changes in the depth of the transit across several wavelengths is equivalent to a ~4.2% change in the apparent planetary radius with wavelength, which is much larger than the atmospheric scale height. This implies the observations probed the atmosphere at very low pressures as well as a dramatic change in the pressure at which the optical depth reaches unity across the bands observed. We hypothesize that the excess absorption may be due to K I in a high-speed wind being driven from the exoplanet's exosphere and discuss the viability of this and alternative interpretations. We also present similar observations of the exoplanet XO-2b that were acquired recently and which are currently being analysed. Finally, we discuss future prospects for exoplanet characterization using tunable filter spectrophotometry.

  5. Vocal tract filtering and the ``coo'' of doves

    NASA Astrophysics Data System (ADS)

    Fletcher, Neville H.; Riede, Tobias; Beckers, Gabriël J. L.; Suthers, Roderick A.

    2004-12-01

    Ring doves (Streptopelia risoria) produce a ``coo'' vocalization that is essentially a pure-tone sound at a frequency of about 600 Hz and with a duration of about 1.5 s. While making this vocalization, the dove inflates the upper part of its esophagus to form a thin-walled sac structure that radiates sound to the surroundings. It is a reasonable assumption that the combined influence of the trachea, glottis and inflated upper esophagus acts as an effective band-pass filter to eliminate higher harmonics generated by the vibrating syringeal valve. Calculations reported here indicate that this is indeed the case. The tracheal tube, terminated by a glottal constriction, is the initial resonant structure, and subsequent resonant filtering takes place through the action of the inflated esophageal sac. The inflated esophagus proves to be a more efficient sound radiating mechanism than an open beak. The action of this sac is only moderately affected by the degree of inflation, although an uninflated esophagus is inactive as a sound radiator. These conclusions are supported by measurements and observations that have been reported in a companion paper. .

  6. Downflow dust filter

    SciTech Connect

    Richard, K.L.

    1986-09-09

    This patent describes an industrial dust filter apparatus comprising: a housing including upper, intermediate and lower sections, the upper section having a top opening inlet for particulate laden gases and the lower section tapering downwardly to a particulate outlet; a plurality of vertically arranged substantially cylindrical filters supported in substantially parallel relationship to each other in the intermediate section of the housing, the filters being closed at their upper ends and having their exterior filter surfaces exposed to particulate laden gases from the inlet; at least one horizontal duct extending across the housing beneath the filters, closed at one end and opening at its other end to a clean gas outlet through a side wall of the intermediate housing section; means communicating the lower open end of the filters through the upper walls of the duct so that the duct functions as a clean gas plenum; a plurality of verturis, vertically supported in the duct, on aligned with each filter; and means in the duct for pulse firing a jet of air upwardly through the venturis into the interior of the filters to remove particulates from the outer surfaces thereof.

  7. Filtering reprecipitated slurry

    SciTech Connect

    Morrissey, M.F.

    1992-12-31

    As part of the Late Washing Demonstration at Savannah River Technology Center, Interim Waste Technology has filtered reprecipitated and non reprecipitated slurry with the Experimental Laboratory Filter (ELF) at TNX. Reprecipitated slurry generates higher permeate fluxes than non reprecipitated slurry. Washing reprecipitated slurry may require a defoamer because reprecipitation encourages foaming.

  8. Filtering reprecipitated slurry

    SciTech Connect

    Morrissey, M.F.

    1992-01-01

    As part of the Late Washing Demonstration at Savannah River Technology Center, Interim Waste Technology has filtered reprecipitated and non reprecipitated slurry with the Experimental Laboratory Filter (ELF) at TNX. Reprecipitated slurry generates higher permeate fluxes than non reprecipitated slurry. Washing reprecipitated slurry may require a defoamer because reprecipitation encourages foaming.

  9. Active rejector filter

    SciTech Connect

    Kuchinskii, A.G.; Pirogov, S.G.; Savchenko, V.M.; Yakushev, A.K.

    1985-01-01

    This paper describes an active rejector filter for suppressing noise signals in the frequency range 50-100 Hz and for extracting a vlf information signal. The filter has the following characteristics: a high input impedance, a resonant frequency of 75 Hz, a Q of 1.25, and an attenuation factor of 53 dB at resonant frequency.

  10. Sintered composite filter

    DOEpatents

    Bergman, W.

    1986-05-02

    A particulate filter medium formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers is described. Preferred composition is about 40 vol.% quartz and about 60 vol.% stainless steel fibers. The media is sintered at about 1100/sup 0/C to bond the stainless steel fibers into a cage network which holds the quartz fibers. High filter efficiency and low flow resistance are provided by the smaller quartz fibers. High strength is provided by the stainless steel fibers. The resulting media has a high efficiency and low pressure drop similar to the standard HEPA media, with tensile strength at least four times greater, and a maximum operating temperature of about 550/sup 0/C. The invention also includes methods to form the composite media and a HEPA filter utilizing the composite media. The filter media can be used to filter particles in both liquids and gases.

  11. Sub-micron filter

    DOEpatents

    Tepper, Frederick; Kaledin, Leonid

    2009-10-13

    Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2/g have been found to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of microbes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolecules such as proteins may be separated from each other based on their electronegative charges.

  12. Implicit Kalman filtering

    NASA Technical Reports Server (NTRS)

    Skliar, M.; Ramirez, W. F.

    1997-01-01

    For an implicitly defined discrete system, a new algorithm for Kalman filtering is developed and an efficient numerical implementation scheme is proposed. Unlike the traditional explicit approach, the implicit filter can be readily applied to ill-conditioned systems and allows for generalization to descriptor systems. The implementation of the implicit filter depends on the solution of the congruence matrix equation (A1)(Px)(AT1) = Py. We develop a general iterative method for the solution of this equation, and prove necessary and sufficient conditions for convergence. It is shown that when the system matrices of an implicit system are sparse, the implicit Kalman filter requires significantly less computer time and storage to implement as compared to the traditional explicit Kalman filter. Simulation results are presented to illustrate and substantiate the theoretical developments.

  13. Multidimensional synthetic estimation filter

    NASA Technical Reports Server (NTRS)

    Monroe, Stanley E., Jr.; Juday, Richard D.

    1990-01-01

    The synthetic estimation filter (SEF) crafts an affine variation into its response to a changing parameter (e.g. scale or rotation). Sets of such filters are used in an estimation correlator to reduce the number of filters required for a given tracking accuracy. By overspecifying the system (one more SEF than parameters to be tracked), the ratio of correlation responses between filters forms a robust estimator into the spanned domain of the parameters. Previous results dealt with a laboratory correlator which could track a single parameter. This paper explores the SEF and the estimator's extension to more dimensions. A 2D example is given in which a reduction of filters from 25 to 3 is demonstrated to span a 4-degree square portion of pose space.

  14. Information geometric nonlinear filtering

    NASA Astrophysics Data System (ADS)

    Newton, Nigel J.

    2015-06-01

    This paper develops information geometric representations for nonlinear filters in continuous time. The posterior distribution associated with an abstract nonlinear filtering problem is shown to satisfy a stochastic differential equation on a Hilbert information manifold. This supports the Fisher metric as a pseudo-Riemannian metric. Flows of Shannon information are shown to be connected with the quadratic variation of the process of posterior distributions in this metric. Apart from providing a suitable setting in which to study such information-theoretic properties, the Hilbert manifold has an appropriate topology from the point of view of multi-objective filter approximations. A general class of finite-dimensional exponential filters is shown to fit within this framework, and an intrinsic evolution equation, involving Amari's -1-covariant derivative, is developed for such filters. Three example systems, one of infinite dimension, are developed in detail.

  15. Dual-wavelength microarray fluorescence detection system using volume holographic filter.

    PubMed

    Fu, Dongxiang; Ma, Junshan; Chen, Jiabi

    2007-01-01

    A dual-wavelength microarray scanner based on laser confocal principle is constructed to acquire the laser-induced two-color fluorescence from dyes Cy3 and Cy5. Unlike most commercially available micoarray scanners whose lasers are continuous wave, filters are bandpass and the channels are multiple photomultiplier tubes (PMTs), the system mainly consists of two diode lasers, four volume holographic band-stop filters, and one PMT. The central wavelengths of two kinds of volume holographic band-stop filters are equal to those of the two laser, respectively. The fluorescence beams can pass through the filters, while laser beams are blocked by them because the filters are cut off. The two fluorescences can pass through a common optical path. Thus, only one pinhole and one PMT are required. The two fluorescences are acquired by the PMT with time sharing. The two respective fluorescences can be gathered when two diode lasers work asynchronously. If lasers work synchronously, the two wavelength fluorescences could be acquired simultaneously by the same PMT. A synthesis of a two-color fluorescence image can be realized straightforwardly in this manner. An experiment is conducted and Cy3 and Cy5 fluorescences are captured. Gridding of the fluorescent images based on basic morphological erosion appropriately locates the boundary between adjacent spots. PMID:17343515

  16. Optimization of spectral filtering parameters of acousto-optic pure rotational Raman lidar for atmospheric temperature profiling

    NASA Astrophysics Data System (ADS)

    Zhu, Jianhua; Wan, Lei; Nie, Guosheng; Guo, Xiaowei

    2003-12-01

    In this paper, as far as we know, it is the first time that a novel acousto-optic pure rotational Raman lidar based on acousto-optic tunable filter (AOTF) is put forward for the application of atmospheric temperature measurements. AOTF is employed in the novel lidar system as narrow band-pass filter and high-speed single-channel wavelength scanner. This new acousto-optic filtering technique can solve the problems of conventional pure rotational Raman lidar, e.g., low temperature detection sensitivity, untunability of filtering parameters, and signal interference between different detection channels. This paper will focus on the PRRS physical model calculation and simulation optimization of system parameters such as the central wavelengths and the bandwidths of filtering operation, and the required sensitivity. The theoretical calculations and optimization of AOTF spectral filtering parameters are conducted to achieve high temperature dependence and sensitivity, high signal intensities, high temperature of filtered spectral passbands, and adequate blocking of elastic Mie and Rayleigh scattering signals. The simulation results can provide suitable proposal and theroetical evaluation before the integration of a practical Raman lidar system.

  17. Properties of Ceramic Filters

    SciTech Connect

    Spain, J.D.

    1996-12-31

    The mechanical integrity of ceramic filter elements is a key issue for hot gas cleanup systems. To meet the demands of advanced power systems, the filter components sustain thermal stresses of normal operations (pulse cleaning), of start-up and shut-down, and of process upsets such as excessive ash accumulation without catastrophic failure. They must also survive various mechanical loads associated with handling and assembly, normal operation, and process upsets. For near-term filter systems, the elements must also survive operating temperature of 1650{degrees}F for three years. Objectives of the testing conducted were as follows: (1) measure basic physical, mechanical and thermal properties of candle filter materials and relate these properties to in-service performance, (2) perform post-exposure testing of candle-filter materials after service at Tidd and Karhula and compare post-exposure results to as-manufactured results to evaluate property degradation, (3) based on measured properties and in-service performance, develop an understanding of material requirements for candle-filter materials and help establish property goals, and (4) establish a test protocol for evaluation of candle filter materials.

  18. Method of filtering

    SciTech Connect

    White, H.R.

    1985-04-09

    This invention provides a non-fibrous combustible filter aid for vacuum pre-coat filter units which is effective to maintain a filter bed coating on rotary filter drums just sufficiently porous to pass the liquid of a slurry while retaining the slurry solids thereon and is capable of being scraped off the bed in thin film form with the slurry solids thereon. The filter aid comprises relatively non-compressible non-fibrous granular charcoal or nut shell particles having a dry bulk density from about 0.3 to about 0.6 grams per cubic centimeter, a particle density of about 1.4 to 1.7 grams per cubis centimeter and a particle size range of 30 to 125 microns. The filter aid of this invention is capable of being burned with the solids deposited thereon to recover the heat value thereof or to dispose of the solids, is free from silicates or other non-combustible ingredients, and is devoid of fibers which will interfere with the proper operation of the filter unit.

  19. Ceramic fiber reinforced filter

    DOEpatents

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  20. Solc filter engineering

    NASA Technical Reports Server (NTRS)

    Rosenberg, W. J.; Title, A. M.

    1982-01-01

    A Solc (1965) filter configuration is presented which is both tunable and spectrally variable, since it possesses an adjustable bandwidth, and which although less efficient than a Lyot filter is attractive because of its spectral versatility. The lossless design, using only an entrance and exit polarizer, improves throughput generally and especially in the IR, where polarizers are less convenient than dichroic sheet polarizers. Attention is given to the transmission profiles of Solc filters with different numbers of elements and split elements, as well as their mechanical design features.

  1. Multilevel filtering elliptic preconditioners

    NASA Technical Reports Server (NTRS)

    Kuo, C. C. Jay; Chan, Tony F.; Tong, Charles

    1989-01-01

    A class of preconditioners is presented for elliptic problems built on ideas borrowed from the digital filtering theory and implemented on a multilevel grid structure. They are designed to be both rapidly convergent and highly parallelizable. The digital filtering viewpoint allows the use of filter design techniques for constructing elliptic preconditioners and also provides an alternative framework for understanding several other recently proposed multilevel preconditioners. Numerical results are presented to assess the convergence behavior of the new methods and to compare them with other preconditioners of multilevel type, including the usual multigrid method as preconditioner, the hierarchical basis method and a recent method proposed by Bramble-Pasciak-Xu.

  2. Parallel Subconvolution Filtering Architectures

    NASA Technical Reports Server (NTRS)

    Gray, Andrew A.

    2003-01-01

    These architectures are based on methods of vector processing and the discrete-Fourier-transform/inverse-discrete- Fourier-transform (DFT-IDFT) overlap-and-save method, combined with time-block separation of digital filters into frequency-domain subfilters implemented by use of sub-convolutions. The parallel-processing method implemented in these architectures enables the use of relatively small DFT-IDFT pairs, while filter tap lengths are theoretically unlimited. The size of a DFT-IDFT pair is determined by the desired reduction in processing rate, rather than on the order of the filter that one seeks to implement. The emphasis in this report is on those aspects of the underlying theory and design rules that promote computational efficiency, parallel processing at reduced data rates, and simplification of the designs of very-large-scale integrated (VLSI) circuits needed to implement high-order filters and correlators.

  3. Improved optical filter

    NASA Technical Reports Server (NTRS)

    Title, A. M.

    1978-01-01

    Filter includes partial polarizer between birefrigent elements. Plastic film on partial polarizer compensates for any polarization rotation by partial polarizer. Two quarter-wave plates change incident, linearly polarized light into elliptically polarized light.

  4. Westinghouse filter update

    SciTech Connect

    Lippert, T.E.; Bruck, G.J.; Smeltzer, E.E.; Newby, R.A.; Bachovchin, D.M.

    1993-09-01

    Hot gas filters have been implemented and operated in four different test facilities: Subpilot scale entrained gasifier, located at the Texaco Montebello Research facilities in California, Foster Wheeler Advanced Pressurized Fluidized Bed Combustion pilot plant facilities, located in Livingston, New Jersey, Slipstream of the American Electric Power (AEP) 70 MW (electric) Tidd-PFBC, located in Brilliant, Ohio, and in the Ahlstrom 10 MW (thermal) Circulating PFBC facility, located in Karhula, Finland. Candle filter testing has occurred at all four facilities; cross flow filter testing has occurred at the Texaco and Foster Wheeler facilities. Table 1 identifies and summarizes the key operating characteristics of these facilities and the type and scale of filter unit tested. A brief description of each project is given.

  5. Active-R filter

    DOEpatents

    Soderstrand, Michael A.

    1976-01-01

    An operational amplifier-type active filter in which the only capacitor in the circuit is the compensating capacitance of the operational amplifiers, the various feedback and coupling elements being essentially solely resistive.

  6. HEPA air filter (image)

    MedlinePlus

    ... pet dander and other irritating allergens from the air. Along with other methods to reduce allergens, such ... controlling the amount of allergens circulating in the air. HEPA filters can be found in most air ...

  7. Anti-Glare Filters

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Glare from CRT screens has been blamed for blurred vision, eyestrain, headaches, etc. Optical Coating Laboratory, Inc. (OCLI) manufactures a coating to reduce glare which was used to coat the windows on the Gemini and Apollo spacecraft. In addition, OCLI offers anti-glare filters (Glare Guard) utilizing the same thin film coating technology. The coating minimizes brightness, provides enhanced contrast and improves readability. The filters are OCLI's first consumer product.

  8. Switching power supply filter

    NASA Technical Reports Server (NTRS)

    Kumar, Prithvi R. (Inventor); Abare, Wayne (Inventor)

    1989-01-01

    A filter for a switching power supply. The filter includes a common mode inductor with coil configurations allowing differential mode current from a dc source to pass through but attenuating common mode noise from the power supply so that the noise does not reach the dc source. The invention also includes the use of feed through capacitors at the switching power supply input terminals to provide further high-frequency noise attenuation.

  9. Contactor/filter improvements

    DOEpatents

    Stelman, David

    1989-01-01

    A contactor/filter arrangement for removing particulate contaminants from a gaseous stream includes a housing having a substantially vertically oriented granular material retention member with upstream and downstream faces, a substantially vertically oriented microporous gas filter element, wherein the retention member and the filter element are spaced apart to provide a zone for the passage of granular material therethrough. The housing further includes a gas inlet means, a gas outlet means, and means for moving a body of granular material through the zone. A gaseous stream containing particulate contaminants passes through the gas inlet means as well as through the upstream face of the granular material retention member, passing through the retention member, the body of granular material, the microporous gas filter element, exiting out of the gas outlet means. Disposed on the upstream face of the filter element is a cover screen which isolates the filter element from contact with the moving granular bed and collects a portion of the particulates so as to form a dust cake having openings small enough to exclude the granular material, yet large enough to receive the dust particles. In one embodiment, the granular material is comprised of prous alumina impregnated with CuO, with the cover screen cleaned by the action of the moving granular material as well as by backflow pressure pulses.

  10. Remotely serviced filter and housing

    DOEpatents

    Ross, Maurice J.; Zaladonis, Larry A.

    1988-09-27

    A filter system for a hot cell comprises a housing adapted for input of air or other gas to be filtered, flow of the air through a filter element, and exit of filtered air. The housing is tapered at the top to make it easy to insert a filter cartridge using an overhead crane. The filter cartridge holds the filter element while the air or other gas is passed through the filter element. Captive bolts in trunnion nuts are readily operated by electromechanical manipulators operating power wrenches to secure and release the filter cartridge. The filter cartridge is adapted to make it easy to change a filter element by using a master-slave manipulator at a shielded window station.

  11. A NUMERICAL METHOD FOR THE VISUALIZATION OF THE Fe XIV EMISSION IN THE SOLAR CORONA USING BROADBAND FILTERS

    SciTech Connect

    Martisek, K.; Druckmuellerova, H.

    2011-12-01

    The goal of this article is to demonstrate how the emission from the Fe XIV 530.3 nm coronal emission line, also known as the green line, can be extracted from images taken during total solar eclipses with commercially available color cameras. This concept is technically feasible because Fe XIV is the brightest optical emission line in the inner corona, and because the sensors of these cameras are retrofitted with a standard Bayer mask, namely, a square grid of spectrally broad (about 100 nm) green, blue, and red filters in the ratio of 2:1:1. The technique presented here, and developed for this purpose, yields qualitatively accurate Fe XIV images, as tested by comparing with Fe XIV eclipse images taken with a 0.15 nm narrow-bandpass filter. While this approach cannot replace narrow-bandpass Fe XIV images for quantitative studies of the corona, it provides a simple and affordable tool for studying the morphology of coronal structures emitting preferentially at the peak ionization temperature of Fe XIV, namely, 1.8 Multiplication-Sign 10{sup 6} K.

  12. Signal-to-noise ratio estimation in digital computer simulation of lowpass and bandpass systems with applications to analog and digital communications, volume 3

    NASA Technical Reports Server (NTRS)

    Tranter, W. H.; Turner, M. D.

    1977-01-01

    Techniques are developed to estimate power gain, delay, signal-to-noise ratio, and mean square error in digital computer simulations of lowpass and bandpass systems. The techniques are applied to analog and digital communications. The signal-to-noise ratio estimates are shown to be maximum likelihood estimates in additive white Gaussian noise. The methods are seen to be especially useful for digital communication systems where the mapping from the signal-to-noise ratio to the error probability can be obtained. Simulation results show the techniques developed to be accurate and quite versatile in evaluating the performance of many systems through digital computer simulation.

  13. Enhancement of seminal stains using background correction algorithm with colour filters.

    PubMed

    Lee, Wee Chuen; Khoo, Bee Ee; Abdullah, Ahmad Fahmi Lim

    2016-06-01

    Evidence in crime scenes available in the form of biological stains which cannot be visualized during naked eye examination can be detected by imaging their fluorescence using a combination of excitation lights and suitable filters. These combinations selectively allow the passage of fluorescence light emitted from the targeted stains. However, interference from the fluorescence generated by many of the surface materials bearing the stains often renders it difficult to visualize the stains during forensic photography. This report describes the use of background correction algorithm (BCA) to enhance the visibility of seminal stain, a biological evidence that fluoresces. While earlier reports described the use of narrow band-pass filters for other fluorescing evidences, here, we utilize BCA to enhance images captured using commonly available colour filters, yellow, orange and red. Mean-based contrast adjustment was incorporated into BCA to adjust the background brightness for achieving similarity of images' background appearance, a crucial step for ensuring success while implementing BCA. Experiment results demonstrated the effectiveness of our proposed colour filters' approach using the improved BCA in enhancing the visibility of seminal stains in varying dilutions on selected surfaces. PMID:27061146

  14. Adaptive filter design based on the LMS algorithm for delay elimination in TCR/FC compensators.

    PubMed

    Hooshmand, Rahmat Allah; Torabian Esfahani, Mahdi

    2011-04-01

    Thyristor controlled reactor with fixed capacitor (TCR/FC) compensators have the capability of compensating reactive power and improving power quality phenomena. Delay in the response of such compensators degrades their performance. In this paper, a new method based on adaptive filters (AF) is proposed in order to eliminate delay and increase the response of the TCR compensator. The algorithm designed for the adaptive filters is performed based on the least mean square (LMS) algorithm. In this design, instead of fixed capacitors, band-pass LC filters are used. To evaluate the filter, a TCR/FC compensator was used for nonlinear and time varying loads of electric arc furnaces (EAFs). These loads caused occurrence of power quality phenomena in the supplying system, such as voltage fluctuation and flicker, odd and even harmonics and unbalancing in voltage and current. The above design was implemented in a realistic system model of a steel complex. The simulation results show that applying the proposed control in the TCR/FC compensator efficiently eliminated delay in the response and improved the performance of the compensator in the power system. PMID:21193194

  15. Alpha-radiation tests on the transmission of cryogenically cooled infrared filter materials used in ISOPHOT

    NASA Astrophysics Data System (ADS)

    Schubert, Josef; Lemke, Dietrich; Kraetschmer, Wolfgang; Mampel, K.

    1995-09-01

    We have studied potential effects of the ISO spacecraft orbital radiation environment on the transmission of infrared interference filters and filter materials. To simulate the critical proton radiation within the earth radiation belts and its influence on the materials at cryogenic temperatures the samples were cooled to LHe temperature and subjected to an Am-241 (alpha) -radiation source (approximately 4.1 MeV) mounted inside a cryostat. The dose per hour absorbed in a 20 micron thick layer, the mean penetration depth for the (alpha) particles, was about 25 krad (Si). The substrates Ge, ZnSe, and CaF2 and three tested ISOPHOT interference bandpass filters (3.21-3.37 micrometers and 2-50 micrometers even after a total dose of approximately 0.5 Mrad (Si), which is more than 100 times the expected total dose for ISOPHOT. The multilayer interference blocking coating on sapphire used on all ISOPHOT far infrared filters to block the wavelength range 1.7-6.7 micrometers showed no degeneration either. The organic far infrared antireflex coating materials polyethylene deposited on a quartz substrate, and a 15 micrometers thick parylene foil used as field lens coating, were investigated in the wavelength range of 16-300 micrometers . Our data suggests a slightly reduced transmission < 6% after 350 krad (Si) exposure.

  16. Filter and method of fabricating

    DOEpatents

    Janney, Mark A.

    2006-02-14

    A method of making a filter includes the steps of: providing a substrate having a porous surface; applying to the porous surface a coating of dry powder comprising particles to form a filter preform; and heating the filter preform to bind the substrate and the particles together to form a filter.

  17. Fabrication and characterization of high order filter based on resonance in hybrid multi-knots microfiber structure

    NASA Astrophysics Data System (ADS)

    Nodehi, S.; Mohammed, W. S.; Ahmad, H.; Harun, S. W.

    2016-04-01

    This work proposes a novel design of a hybrid microfiber resonator which can be used as a band-pass and band-stop filter in various applications such as fiber lasers. The structure comprises of two microfiber knot resonators with different sizes which are surrounded by a semi-loop structure with one input and two output ports. Utilization of the Vernier effect in the proposed structure showed an enhancement of the free spectral range (FSR). The finesse has increased by a factor of three compared to a single knot providing a sharper roll-off. The filter bandwidth is adjustable as a result of the manipulation of the coupling length and rings' radii. The performance of the device is explained theoretically using transfer matrix analysis.

  18. The impact of head movements on EEG and contact impedance: an adaptive filtering solution for motion artifact reduction.

    PubMed

    Mihajlovic, Vojkan; Patki, Shrishail; Grundlehner, Bernard

    2014-01-01

    Designing and developing a comfortable and convenient EEG system for daily usage that can provide reliable and robust EEG signal, encompasses a number of challenges. Among them, the most ambitious is the reduction of artifacts due to body movements. This paper studies the effect of head movement artifacts on the EEG signal and on the dry electrode-tissue impedance (ETI), monitored continuously using the imec's wireless EEG headset. We have shown that motion artifacts have huge impact on the EEG spectral content in the frequency range lower than 20 Hz. Coherence and spectral analysis revealed that ETI is not capable of describing disturbances at very low frequencies (below 2 Hz). Therefore, we devised a motion artifact reduction (MAR) method that uses a combination of a band-pass filtering and multi-channel adaptive filtering (AF), suitable for real-time MAR. This method was capable of substantially reducing artifacts produced by head movements. PMID:25571131

  19. Remotely serviced filter and housing

    DOEpatents

    Ross, M.J.; Zaladonis, L.A.

    1987-07-22

    A filter system for a hot cell comprises a housing adapted for input of air or other gas to be filtered, flow of the air through a filter element, and exit of filtered air. The housing is tapered at the top to make it easy to insert a filter cartridge holds the filter element while the air or other gas is passed through the filter element. Captive bolts in trunnion nuts are readily operated by electromechanical manipulators operating power wrenches to secure and release the filter cartridge. The filter cartridge is adapted to make it easy to change a filter element by using a master-slave manipulator at a shielded window station. 6 figs.

  20. An IIR median hybrid filter

    NASA Technical Reports Server (NTRS)

    Bauer, Peter H.; Sartori, Michael A.; Bryden, Timothy M.

    1992-01-01

    A new class of nonlinear filters, the so-called class of multidirectional infinite impulse response median hybrid filters, is presented and analyzed. The input signal is processed twice using a linear shift-invariant infinite impulse response filtering module: once with normal causality and a second time with inverted causality. The final output of the MIMH filter is the median of the two-directional outputs and the original input signal. Thus, the MIMH filter is a concatenation of linear filtering and nonlinear filtering (a median filtering module). Because of this unique scheme, the MIMH filter possesses many desirable properties which are both proven and analyzed (including impulse removal, step preservation, and noise suppression). A comparison to other existing median type filters is also provided.

  1. Filters for cathodic arc plasmas

    DOEpatents

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  2. Anti-clogging filter system

    SciTech Connect

    Brown, Erik P.

    2015-05-19

    An anti-clogging filter system for filtering a fluid containing large particles and small particles includes an enclosure with at least one individual elongated tubular filter element in the enclosure. The individual elongated tubular filter element has an internal passage, a closed end, an open end, and a filtering material in or on the individual elongated tubular filter element. The fluid travels through the open end of the elongated tubular element and through the internal passage and through the filtering material. An anti-clogging element is positioned on or adjacent the individual elongated tubular filter element and provides a fluid curtain that preferentially directs the larger particulates to one area of the filter material allowing the remainder of the filter material to remain more efficient.

  3. Filter cake characterization studies

    SciTech Connect

    Newby, R.A.; Smeltzer, E.E.; Alvin, M.A.; Lippert, T.E.

    1995-11-01

    The Westinghouse Electric Corporation, Science & Technology Center is developing an Integrated Low Emissions Cleanup (ILEC) concept for high-temperature gas cleaning to meet environmental standards, as well as to provide gas turbine protection. The ILEC system is a ceramic barrier hot gas filter (HGF) that removes particulate while simultaneously contributing to the control of sulfur, alkali, and potentially other contaminants in high-temperature, high-pressure fuel gases, or combustion gases. The gas-phase contaminant removal is performed by sorbent particles injected into the HGF. The overall objective of this program is to demonstrate, at a bench scale, the technical feasibility of the ILEC concept for multi-contaminant control, and to provide test data applicable to the design of subsequent field tests. The program has conducted ceramic barrier filter testing under simulated PFBC conditions to resolve issues relating to filter cake permeability, pulse cleaning, and filter cake additive performance. ILEC testing has also been performed to assess the potential for in-filter sulfur and alkali removal.

  4. Filter component assessment

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Diaz, E.S.; Smeltzer, E.W.

    1995-11-01

    The objectives of this program are to provide a more ruggedized filter system that utilizes porous ceramic filters which have improved resistance to damage resulting from crack propagation, thermal fatigue and/or thermal excursions during plant or process transient conditions, and/or mechanical ash bridging events within the candle filter array. As part of the current Phase 1, Task 1, effort of this program, Westinghouse is evaluating the filtration characteristics, mechanical integrity, and corrosion resistance of the following advanced or second generation candle filters for use in advanced coal-fired process applications: 3M CVI-SiC composite--chemical vapor infiltration of silicon carbide into an aluminosilicate Nextel{trademark} 312 fiber preform; DuPont PRD-66--filament wound candle filter structure containing corundum, cordierite, cristobalite, and mullite; DuPont SiC-SiC--chemical infiltration of silicon carbide into a silicon carbide Nicalon{trademark} fiber mat or felt preform; and IF and P Fibrosic{trademark}--vacuum infiltrated oxide-based chopped fibrous matrix. Results to date are presented.

  5. Multilayer volume microwave filters

    NASA Astrophysics Data System (ADS)

    Gvozdev, V. I.; Smirnov, S. V.; Chernushenko, A. M.

    1985-09-01

    Multilayer volume microwave filters are particularly suitable for miniaturization of radioelectronic devices by way of circuit integration, the principal advantage over planar filters being the much higher Q-factor; Q sub 0 or = 10 to the 3rd power as compared with Q sub 0 or = 10 to the 2nd power. Their metal-dielectric structure forms an array of coupled half-wavelength resonators electrically symmetric with respect to the center layer, coupling being effected by a magnetic field normal to the plane of resonators. The structure consists of an asymmetric strip line with conductor at the input end, followed by a metal layer with cut out symmetric slot line, a dielectric layer, a symmetric strip line with conductor, a metal layer with cut out symmetric slot line, a dielectric layer, and an asymmetric strip line with conductor at the output end. The size of such a filter depends directly on the number of resonator stages and, without the case, is comparable with the size of conventional filters on symmetric strip lines only but is much smaller than that of conventional filters on asymmetric strip lines only.

  6. Properties of ceramic candle filters

    SciTech Connect

    Pontius, D.H.; Starrett, H.S.

    1994-10-01

    The objectives of this program have been: (1) the post-test evaluation of candle filters, (2) to measure the material properties of current filter materials, destructively and non-destructively, and to relate these properties and behaviors to in-service performance, (3) to develop an understanding of the material requirements for hot gas filter elements, (4) to develop material property goals for filter materials, and (5) to establish test matrices and a protocol to evaluate candidate filter materials.

  7. Filters for Submillimeter Electromagnetic Waves

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M.

    1986-01-01

    New manufacturing process produces filters strong, yet have small, precise dimensions and smooth surface finish essential for dichroic filtering at submillimeter wavelengths. Many filters, each one essentially wafer containing fine metal grid made at same time. Stacked square wires plated, fused, and etched to form arrays of holes. Grid of nickel and tin held in brass ring. Wall thickness, thickness of filter (hole depth) and lateral hole dimensions all depend upon operating frequency and filter characteristics.

  8. Disinfecting Filters For Recirculated Air

    NASA Technical Reports Server (NTRS)

    Pilichi, Carmine A.

    1992-01-01

    Simple treatment disinfects air filters by killing bacteria, algae, fungi, mycobacteria, viruses, spores, and any other micro-organisms filters might harbor. Concept applied to reusable stainless-steel wire mesh filters and disposable air filters. Treatment used on filters in air-circulation systems in spacecraft, airplanes, other vehicles, and buildings to help prevent spread of colds, sore throats, and more-serious illnesses.

  9. DOE HEPA filter test program

    SciTech Connect

    1998-05-01

    This standard establishes essential elements of a Department of Energy (DOE) program for testing HEPA filters to be installed in DOE nuclear facilities or used in DOE-contracted activities. A key element is the testing of HEPA filters for performance at a DOE Filter Test Facility (FTF) prior to installation. Other key elements are (1) providing for a DOE HEPA filter procurement program, and (2) verifying that HEPA filters to be installed in nuclear facilities appear on a Qualified Products List (QPL).

  10. Stack filter classifiers

    SciTech Connect

    Porter, Reid B; Hush, Don

    2009-01-01

    Just as linear models generalize the sample mean and weighted average, weighted order statistic models generalize the sample median and weighted median. This analogy can be continued informally to generalized additive modeels in the case of the mean, and Stack Filters in the case of the median. Both of these model classes have been extensively studied for signal and image processing but it is surprising to find that for pattern classification, their treatment has been significantly one sided. Generalized additive models are now a major tool in pattern classification and many different learning algorithms have been developed to fit model parameters to finite data. However Stack Filters remain largely confined to signal and image processing and learning algorithms for classification are yet to be seen. This paper is a step towards Stack Filter Classifiers and it shows that the approach is interesting from both a theoretical and a practical perspective.

  11. Kalman filter modeling

    NASA Technical Reports Server (NTRS)

    Brown, R. G.

    1984-01-01

    The formulation of appropriate state-space models for Kalman filtering applications is studied. The so-called model is completely specified by four matrix parameters and the initial conditions of the recursive equations. Once these are determined, the die is cast, and the way in which the measurements are weighted is determined foreverafter. Thus, finding a model that fits the physical situation at hand is all important. Also, it is often the most difficult aspect of designing a Kalman filter. Formulation of discrete state models from the spectral density and ARMA random process descriptions is discussed. Finally, it is pointed out that many common processes encountered in applied work (such as band-limited white noise) simply do not lend themselves very well to Kalman filter modeling.

  12. Fourier-based segmentation of microcalcifications in mammograms

    NASA Astrophysics Data System (ADS)

    López-Meléndez, Elizabeth; Lara-Rodríguez, Luis David; Urcid, Gonzalo

    2015-09-01

    This paper presents a Fourier transform approach to detect microcalcifications in digital mammograms. The basic idea consists in the design of parametric Butterworth bandpass filters in the Fourier domain used to extract sharpened border like structures that correspond to detected mammography microcalcifications. Image thresholding of the filtered image is accomplished, first by homogenizing the background (fibroglandular tissue) with a median filter, after which a gamma correction is applied to change the global contrast. Second, by postprocessing the resulting image using histogram based local and global statistics we obtain a properly binarized image that emphasizes the desired objects (microcalcifications) and segmentation is completed using a sequence of morphological binary operations. Several illustrative examples taken from a clinical database are included to demonstrate the capability of the proposed approach in comparison with other edge detection techniques such as the difference of Gaussians (DoG) and the Laplacian of a Gaussian (LoG).

  13. Groundspeed filtering for CTAS

    NASA Technical Reports Server (NTRS)

    Slater, Gary L.

    1994-01-01

    Ground speed is one of the radar observables which is obtained along with position and heading from NASA Ames Center radar. Within the Center TRACON Automation System (CTAS), groundspeed is converted into airspeed using the wind speeds which CTAS obtains from the NOAA weather grid. This airspeed is then used in the trajectory synthesis logic which computes the trajectory for each individual aircraft. The time history of the typical radar groundspeed data is generally quite noisy, with high frequency variations on the order of five knots, and occasional 'outliers' which can be significantly different from the probable true speed. To try to smooth out these speeds and make the ETA estimate less erratic, filtering of the ground speed is done within CTAS. In its base form, the CTAS filter is a 'moving average' filter which averages the last ten radar values. In addition, there is separate logic to detect and correct for 'outliers', and acceleration logic which limits the groundspeed change in adjacent time samples. As will be shown, these additional modifications do cause significant changes in the actual groundspeed filter output. The conclusion is that the current ground speed filter logic is unable to track accurately the speed variations observed on many aircraft. The Kalman filter logic however, appears to be an improvement to the current algorithm used to smooth ground speed variations, while being simpler and more efficient to implement. Additional logic which can test for true 'outliers' can easily be added by looking at the difference in the a priori and post priori Kalman estimates, and not updating if the difference in these quantities is too large.

  14. Electronically tuned optical filters

    NASA Technical Reports Server (NTRS)

    Castellano, J. A.; Pasierb, E. F.; Oh, C. S.; Mccaffrey, M. T.

    1972-01-01

    A detailed account is given of efforts to develop a three layer, polychromic filter that can be tuned electronically. The operation of the filter is based on the cooperative alignment of pleochroic dye molecules by nematic liquid crystals activated by electric fields. This orientation produces changes in the optical density of the material and thus changes in the color of light transmitted through the medium. In addition, attempts to improve materials and devices which employ field induced changes of a cholesteric to a nematic liquid crystal are presented.

  15. New electronically tunable current-mode universal biquad filter using translinear current conveyors

    NASA Astrophysics Data System (ADS)

    Kumngern, Montree; Jongchanachavawat, Wirote; Dejhan, Kobchai

    2010-05-01

    In this study, a new electronically tunable current-mode universal filter with two inputs and two outputs employing one translinear current conveyor, one translinear current conveyor with controlled current gain and two grounded capacitors is presented. The proposed circuit offers the following attractive features: realisation of low-pass, band-pass, high-pass, band-stop and all-pass current responses from the same configuration; employment of the minimum active and passive components; no requirement of component matching conditions; independent current-control of the parameters natural frequency (ωo) and quality factor (Q); low active and passive sensitivities; and high impedance output. The characteristics of the proposed circuit are simulated using PSPICE to confirm the theory.

  16. Cryo-Transmittance and -Reflectance of Filters and Beamsplitters for the SIRTF Infrared Array Camera

    NASA Technical Reports Server (NTRS)

    Stewart, Kenneth P.; Quijada, Manuel A.a

    2000-01-01

    The Space Infrared Telescope Facility (SIRTF) Infrared Array Camera (IRAC) uses two dichroic beamsplitters, four bandpass filters, and four detector arrays to acquire images in four channels at wavelengths between 3 and 10 micron. Accurate knowledge of the pass bands is necessary because, in order to meet the science objectives, IRAC is required to do 2% relative photometry in each band relative to the other bands. We report the in-band and out-of-band polarized transmittance and reflectance of these optical elements measured near the instrument operating temperature of 1.4 K. Details of the experimental apparatus, which include a continuous flow liquid helium optical cryostat and a Fourier transform infrared (FTIR) spectrometer are discussed.

  17. Supervised Material Classification in Oblique Aerial Imagery Using Gabor Filter Features

    NASA Astrophysics Data System (ADS)

    Harris, Michael L.

    RIT's Digital Imaging and Remote Sensing Image Generation (DIRSIG) tool allows modeling of real world scenes to create synthetic imagery for sensor design and analysis, trade studies, algorithm validation, and training image analysts. To increase model construction speed, and the diversity and size of synthetic scenes which can be generated it is desirable to automatically segment real world imagery into different material types and import a material classmap into DIRSIG. This work contributes a methodology based on standard texture recognition techniques to supervised classification of material types in oblique aerial imagery. Oblique imagery provides many challenges for texture recognition due to illumination changes with view angle, projective distortions, occlusions and self shadowing. It is shown that features derived from a set of rotationally invariant bandpass filters fused with color channel information can provide supervised classification accuracies up to 70% with minimal training data.

  18. Two-mode model for metal-dielectric guided-mode resonance filters.

    PubMed

    Tuambilangana, Christelle; Pardo, Fabrice; Sakat, Emilie; Bouchon, Patrick; Pelouard, Jean-Luc; Haïdar, Riad

    2015-12-14

    Symmetric metal-dielectric guided-mode resonators (GMR) can operate as infrared band-pass filters, thanks to high-transmission resonant peaks and good rejection ratio. Starting from matrix formalism, we show that the behavior of the system can be described by a two-mode model. This model reduces to a scalar formula and the GMR is described as the combination of two independent Fabry-Perot resonators. The formalism has then been applied to the case of asymmetric GMR, in order to restore the properties of the symmetric system. This result allows designing GMR-on-substrate as efficient as free-standing systems, the same high transmission maximum value and high quality factor being conserved. PMID:26698960

  19. Characterization of a Dielectric E-Plane Loaded Waveguide by the NMVF: Application to Filters Design

    NASA Astrophysics Data System (ADS)

    Lilonga-Boyenga, Desire; Okoumou Moko, Gilbert

    The rectangular E-plane dielectric loaded metallic waveguide equivalent circuit with dielectric of an arbitrary shape, occupying all height of the waveguide is established using the New Multimodal Variational Formulation (NMVF). The advantage of this rigorous approach compared to the traditional multimodal variational formulation lies in the taking into account of all higher-order modes of the intermediate waveguides in the calculation of the overall structure's impedance matrix Z, thus resulting in increasing the results accuracy and decreasing the computing time. This new passive microwave components analysis and aided-design tool is applied firstly to analyze a rectangular loaded waveguide with one and two centered cylindrical dielectric posts and then one section transformer dielectric phase shifter and secondly, to design an evanescent dielectric resonators band-pass filter in X-band. The results obtained are in good agreement with literature data and FEM software simulations.

  20. Design of Microwave Front-End Narrowband Filter and Limiter Components

    NASA Astrophysics Data System (ADS)

    Cross, Lee W.

    This dissertation proposes three novel bandpass filter structures to protect systems exposed to damaging levels of electromagnetic (EM) radiation from intentional and unintentional high-power microwave (HPM) sources. This is of interest because many commercial microwave communications and sensor systems are unprotected from high power levels. Novel technologies to harden front-end components must maintain existing system performance and cost. The proposed concepts all use low-cost printed circuit board (PCB) fabrication to create compact solutions that support high integration. The first proposed filter achieves size reduction of 46% using a technology that is suitable for low-loss, narrowband filters that can handle high power levels. This is accomplished by reducing a substrate-integrated waveguide (SIW) loaded evanescent-mode bandpass filter to a half-mode SIW (HMSIW) structure. Demonstrated third-order SIW and HMSIW filters have 1.7 GHz center frequency and 0.2 GHz bandwidth. Simulation and measurements of the filters utilizing combline resonators prove the underlying principles. The second proposed device combines a traditional microstrip bent hairpin filter with encapsulated gas plasma elements to create a filter-limiter: a novel narrowband filter with integral HPM limiter behavior. An equivalent circuit model is presented for the ac coupled plasma-shell components used in this dissertation, and parameter values were extracted from measured results and EM simulation. The theory of operation of the proposed filter-limiter was experimentally validated and key predictions were demonstrated including two modes of operation in the on state: a constant output power mode and constant attenuation mode at high power. A third-order filter-limiter with center frequency of 870 MHz was demonstrated. It operates passively from incident microwave energy, and can be primed with an external voltage source to reduce both limiter turn-on threshold power and output power

  1. High temperature filter materials

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M.; Tressler, R.E.

    1992-12-01

    Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100{degrees}C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter {times} 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.

  2. High temperature filter materials

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M. . Science and Technology Center); Tressler, R.E. )

    1992-01-01

    Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100[degrees]C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter [times] 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.

  3. Digital hum filtering

    USGS Publications Warehouse

    Knapp, R.W.; Anderson, N.L.

    1994-01-01

    Data may be overprinted by a steady-state cyclical noise (hum). Steady-state indicates that the noise is invariant with time; its attributes, frequency, amplitude, and phase, do not change with time. Hum recorded on seismic data usually is powerline noise and associated higher harmonics; leakage from full-waveform rectified cathodic protection devices that contain the odd higher harmonics of powerline frequencies; or vibrational noise from mechanical devices. The fundamental frequency of powerline hum may be removed during data acquisition with the use of notch filters. Unfortunately, notch filters do not discriminate signal and noise, attenuating both. They also distort adjacent frequencies by phase shifting. Finally, they attenuate only the fundamental mode of the powerline noise; higher harmonics and frequencies other than that of powerlines are not removed. Digital notch filters, applied during processing, have many of the same problems as analog filters applied in the field. The method described here removes hum of a particular frequency. Hum attributes are measured by discrete Fourier analysis, and the hum is canceled from the data by subtraction. Errors are slight and the result of the presence of (random) noise in the window or asynchrony of the hum and data sampling. Error is minimized by increasing window size or by resampling to a finer interval. Errors affect the degree of hum attenuation, not the signal. The residual is steady-state hum of the same frequency. ?? 1994.

  4. Multichannel birefringent filter

    NASA Technical Reports Server (NTRS)

    Gouxiang, A.; Huefeng, H.

    1985-01-01

    A birefringent filter with a large field of view and no additional polarization is discussed. It plays an important role in observing the solar monochromatic image and the solar vector magnetic field. It has only one channel. For simultaneous multichannel observations, the solar spectrograph is better than the birefringent filter. A suggestion was proposed to try to obtain a multichannel birefringent filter which will be used in a new telescope at the Huairou reservoir station of Beijing Observatory. By means of N polarizing beam splitters, (N+1) channels can be divided. In principle, any number of limitless channels can be obtained, thereby subdividing the whole solar spectrum. But since the space in a telescope is limited, the channels to be used are also limited. For the new telescope, 5 and 9 channels are being considered, and the spectral range is from lambda 3800A to lambda 7000A. Many lines are included in this range, for example, H, K, H beta, lambda lambda 5324A, 5250A, 6302A, H alpha, etc., and some of the lines are suited to measure solar velocity fields. According to the character of these lines, the half width of each channel is determined. Moreover, in some channels the solid polarizing Michelson interferometer is considered for measuring velocity field with a lm/s accuracy. The advantages of the filter and problems to be solved are listed.

  5. Ozone decomposing filter

    DOEpatents

    Simandl, Ronald F.; Brown, John D.; Whinnery, Jr., LeRoy L.

    1999-01-01

    In an improved ozone decomposing air filter carbon fibers are held together with a carbonized binder in a perforated structure. The structure is made by combining rayon fibers with gelatin, forming the mixture in a mold, freeze-drying, and vacuum baking.

  6. Foam For Filtering

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Like nature's honeycomb, foam is a structure of many-sided cells, apparently solid but actually only three percent material and 97 percent air. Foam is made by a heat-producing chemical reaction which expands a plastic material in a manner somewhat akin to the heat-induced rising of a loaf of bread. The resulting structure of interconnected cells is flexible yet strong and extremely versatile in applicati6n. Foam can, for example, be a sound absorber in one form, while in another it allows sound to pass through it. It can be a very soft powder puff material and at the same time a highly abrasive scrubber. A sampling of foam uses includes stereo speaker grilles, applying postage meter ink, filtering lawnmower carburetor air; deadening noise in trucks and tractors, applying cosmetics, releasing fabric softener and antistatic agents in home clothes dryers, painting, filtering factory heating and ventilating systems, shining shoes, polishing cars, sponge-mopping floors, acting as pre-operative surgical scrubbers-the list is virtually limitless. The process by which foam is made produces "windows," thin plastic membranes connecting the cell walls. Windowed foam is used in many applications but for certain others-filtering, for example-it is desirable to have a completely open network. Scott Paper Company's Foam Division, Chester, Pennsylvania, improved a patented method of "removing the windows," to create an open structure that affords special utility in filtering applications. NASA technology contributed to Scott's improvement.

  7. Rotating drum filter

    DOEpatents

    Anson, Donald

    1990-01-01

    A perforated drum (10) rotates in a coaxial cylindrical housing (18) having three circumferential ports (19,22,23), and an axial outlet (24) at one end. The axis (11) is horizontal. A fibrous filter medium (20) is fed through a port (19) on or near the top of the housing (81) by a distributing mechanism (36) which lays a uniform mat (26) of the desired thickness onto the rotating drum (10). This mat (26) is carried by the drum (10) to a second port (23) through which dirty fluid (13) enters. The fluid (13) passes through the filter (26) and the cleaned stream (16) exits through the open end (15) of the drum (10) and the axial port (24) in the housing (18). The dirty filter material (20) is carried on to a third port (22) near the bottom of the housing (18) and drops into a receiver (31) from which it is continuously removed, cleaned (30), and returned (32) to the charging port (36) at the top. To support the filter mat, the perforated cylinder may carry a series of tines (40), shaped blades (41), or pockets, so that the mat (26) will not fall from the drum (10) prematurely. To minimize risk of mat failure, the fluid inlet port (23) may be located above the horizontal centerline (11).

  8. Ozone decomposing filter

    SciTech Connect

    Simandl, R.F.; Brown, J.D.; Whinnery, L.L. Jr.

    1999-11-02

    In an improved ozone decomposing air filter carbon fibers are held together with a carbonized binder in a perforated structure. The structure is made by combining rayon fibers with gelatin, forming the mixture in a mold, freeze-drying, and vacuum baking.

  9. Compressive Bilateral Filtering.

    PubMed

    Sugimoto, Kenjiro; Kamata, Sei-Ichiro

    2015-11-01

    This paper presents an efficient constant-time bilateral filter that produces a near-optimal performance tradeoff between approximate accuracy and computational complexity without any complicated parameter adjustment, called a compressive bilateral filter (CBLF). The constant-time means that the computational complexity is independent of its filter window size. Although many existing constant-time bilateral filters have been proposed step-by-step to pursue a more efficient performance tradeoff, they have less focused on the optimal tradeoff for their own frameworks. It is important to discuss this question, because it can reveal whether or not a constant-time algorithm still has plenty room for improvements of performance tradeoff. This paper tackles the question from a viewpoint of compressibility and highlights the fact that state-of-the-art algorithms have not yet touched the optimal tradeoff. The CBLF achieves a near-optimal performance tradeoff by two key ideas: 1) an approximate Gaussian range kernel through Fourier analysis and 2) a period length optimization. Experiments demonstrate that the CBLF significantly outperforms state-of-the-art algorithms in terms of approximate accuracy, computational complexity, and usability. PMID:26068315

  10. Counting digital filters

    NASA Technical Reports Server (NTRS)

    Zohar, S. (Inventor)

    1973-01-01

    Several embodiments of a counting digital filter of the non-recursive type are disclosed. In each embodiment two registers, at least one of which is a shift register, are included. The shift register received j sub x-bit data input words bit by bit. The kth data word is represented by the integer.

  11. Filter Component Assessment

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Diaz, E.S.; Smeltzer, E.E.

    1996-12-31

    Advanced particulate filtration systems are currently being developed at Westinghouse for use in both coal-fired Integrated Gasification Combined Cycle (IGCC) and Pressurized Fluidized Bed Combustion (PFBC) systems. To date, Westinghouse has demonstrated 5855 hours of successful operation of first generation monolithic filter elements in PFBC applications when ash bridging or process thermal transient excursions are avoided. Alternate advanced monolithic and second generation fiber reinforced, filament wound and vacuum infiltrated filters are also being developed which are considered to have enhanced high temperature creep resistance, improved fracture toughness, or enhanced thermal shock characteristics, respectively. Mechanical and component fabrication improvements, as well as degradation mechanisms for each filter element have been identified by Westinghouse during exposure to simulated PFBC operating conditions and alkali-containing steam/air environments. Additional effort is currently being focused on determining the stability of the advanced monolithic high temperature creep resistant clay bonded silicon carbide (SiC) materials, alumina/mullite, and chemically vapor infiltrated (CVI) SiC materials during operation in the Westinghouse Advanced Particulate Filtration (W-APF) system at Foster Wheeler`s pressurized circulating fluidized-bed combustion (PCFBC) test facility in Karhula, Finland. Select advanced filter materials are being defined for additional long-term exposure in integrated gasification combined cycle (IGCC) gas streams. The results of these efforts are summarized in this paper. 6 refs., 7 figs., 11 tabs.

  12. Domain wall filters

    SciTech Connect

    Baer, Oliver; Narayanan, Rajamani; Neuberger, Herbert; Witzel, Oliver

    2007-03-15

    We propose using the extra dimension separating the domain walls carrying lattice quarks of opposite handedness to gradually filter out the ultraviolet fluctuations of the gauge fields that are felt by the fermionic excitations living in the bulk. This generalization of the homogeneous domain wall construction has some theoretical features that seem nontrivial.

  13. Ceramic HEPA Filter Program

    SciTech Connect

    Mitchell, M A; Bergman, W; Haslam, J; Brown, E P; Sawyer, S; Beaulieu, R; Althouse, P; Meike, A

    2012-04-30

    Potential benefits of ceramic filters in nuclear facilities: (1) Short term benefit for DOE, NRC, and industry - (a) CalPoly HTTU provides unique testing capability to answer questions for DOE - High temperature testing of materials, components, filter, (b) Several DNFSB correspondences and presentations by DNFSB members have highlighted the need for HEPA filter R and D - DNFSB Recommendation 2009-2 highlighted a nuclear facility response to an evaluation basis earthquake followed by a fire (aka shake-n-bake) and CalPoly has capability for a shake-n-bake test; (2) Intermediate term benefit for DOE and industry - (a) Filtration for specialty applications, e.g., explosive applications at Nevada, (b) Spin-off technologies applicable to other commercial industries; and (3) Long term benefit for DOE, NRC, and industry - (a) Across industry, strong desire for better performance filter, (b) Engineering solution to safety problem will improve facility safety and decrease dependence on associated support systems, (c) Large potential life-cycle cost savings, and (d) Facilitates development and deployment of LLNL process innovations to allow continuous ventilation system operation during a fire.

  14. INTERIOR VIEW OF FILTER WHEEL MACHINE USED TO FILTER OUT ...

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

    INTERIOR VIEW OF FILTER WHEEL MACHINE USED TO FILTER OUT AND SEPARATE BICARBONATE FROM AMMONIONATED BRINE. DISCHARGE FROM STRIPPER COLUMNS (SOLVAY COLUMNS). - Solvay Process Company, SA Wetside Building, Between Willis & Milton Avenue, Solvay, Onondaga County, NY

  15. Filter assembly for metallic and intermetallic tube filters

    DOEpatents

    Alvin, Mary Anne; Lippert, Thomas E.; Bruck, Gerald J.; Smeltzer, Eugene E.

    2001-01-01

    A filter assembly (60) for holding a filter element (28) within a hot gas cleanup system pressure vessel is provided, containing: a filter housing (62), said filter housing having a certain axial length and having a peripheral sidewall, said sidewall defining an interior chamber (66); a one piece, all metal, fail-safe/regenerator device (68) within the interior chamber (66) of the filter housing (62) and/or extending beyond the axial length of the filter housing, said device containing an outward extending radial flange (71) within the filter housing for seating an essential seal (70), the device also having heat transfer media (72) disposed inside and screens (80) for particulate removal; one compliant gasket (70) positioned next to and above the outward extending radial flange of the fail-safe/regenerator device; and a porous metallic corrosion resistant superalloy type filter element body welded at the bottom of the metal fail-safe/regenerator device.

  16. DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.

    EPA Science Inventory

    The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...

  17. Versatile tunable current-mode universal biquadratic filter using MO-DVCCs and MOSFET-based electronic resistors.

    PubMed

    Chen, Hua-Pin

    2014-01-01

    This paper presents a versatile tunable current-mode universal biquadratic filter with four-input and three-output employing only two multioutput differential voltage current conveyors (MO-DVCCs), two grounded capacitors, and a well-known method for replacement of three grounded resistors by MOSFET-based electronic resistors. The proposed configuration exhibits high-output impedance which is important for easy cascading in the current-mode operations. The proposed circuit can be used as either a two-input three-output circuit or a three-input single-output circuit. In the operation of two-input three-output circuit, the bandpass, highpass, and bandreject filtering responses can be realized simultaneously while the allpass filtering response can be easily obtained by connecting appropriated output current directly without using additional stages. In the operation of three-input single-output circuit, all five generic filtering functions can be easily realized by selecting different three-input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no inverting-type input current signals are imposed. All the passive and active sensitivities are low. Postlayout simulations were carried out to verify the functionality of the design. PMID:24982963

  18. Versatile Tunable Current-Mode Universal Biquadratic Filter Using MO-DVCCs and MOSFET-Based Electronic Resistors

    PubMed Central

    2014-01-01

    This paper presents a versatile tunable current-mode universal biquadratic filter with four-input and three-output employing only two multioutput differential voltage current conveyors (MO-DVCCs), two grounded capacitors, and a well-known method for replacement of three grounded resistors by MOSFET-based electronic resistors. The proposed configuration exhibits high-output impedance which is important for easy cascading in the current-mode operations. The proposed circuit can be used as either a two-input three-output circuit or a three-input single-output circuit. In the operation of two-input three-output circuit, the bandpass, highpass, and bandreject filtering responses can be realized simultaneously while the allpass filtering response can be easily obtained by connecting appropriated output current directly without using additional stages. In the operation of three-input single-output circuit, all five generic filtering functions can be easily realized by selecting different three-input current signals. The filter permits orthogonal controllability of the quality factor and resonance angular frequency, and no inverting-type input current signals are imposed. All the passive and active sensitivities are low. Postlayout simulations were carried out to verify the functionality of the design. PMID:24982963

  19. OPTIMIZATION OF ADVANCED FILTER SYSTEMS

    SciTech Connect

    R.A. Newby; M.A. Alvin; G.J. Bruck; T.E. Lippert; E.E. Smeltzer; M.E. Stampahar

    2002-06-30

    Two advanced, hot gas, barrier filter system concepts have been proposed by the Siemens Westinghouse Power Corporation to improve the reliability and availability of barrier filter systems in applications such as PFBC and IGCC power generation. The two hot gas, barrier filter system concepts, the inverted candle filter system and the sheet filter system, were the focus of bench-scale testing, data evaluations, and commercial cost evaluations to assess their feasibility as viable barrier filter systems. The program results show that the inverted candle filter system has high potential to be a highly reliable, commercially successful, hot gas, barrier filter system. Some types of thin-walled, standard candle filter elements can be used directly as inverted candle filter elements, and the development of a new type of filter element is not a requirement of this technology. Six types of inverted candle filter elements were procured and assessed in the program in cold flow and high-temperature test campaigns. The thin-walled McDermott 610 CFCC inverted candle filter elements, and the thin-walled Pall iron aluminide inverted candle filter elements are the best candidates for demonstration of the technology. Although the capital cost of the inverted candle filter system is estimated to range from about 0 to 15% greater than the capital cost of the standard candle filter system, the operating cost and life-cycle cost of the inverted candle filter system is expected to be superior to that of the standard candle filter system. Improved hot gas, barrier filter system availability will result in improved overall power plant economics. The inverted candle filter system is recommended for continued development through larger-scale testing in a coal-fueled test facility, and inverted candle containment equipment has been fabricated and shipped to a gasifier development site for potential future testing. Two types of sheet filter elements were procured and assessed in the program

  20. Active resistance capacitance filter design

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.

    1970-01-01

    Filters, formed by combinations of distributed RC elements with positive-feedback voltage amplifiers, provide transfer functions similar to those the heavier LC filters ordinarily employ. They also provide signal amplification.

  1. The Magnetic Centrifugal Mass Filter

    SciTech Connect

    Abraham J. Fetterman and Nathaniel J. Fisch

    2011-08-04

    Mass filters using rotating plasmas have been considered for separating nuclear waste and spent nuclear fuel. We propose a new mass filter that utilizes centrifugal and magnetic confinement of ions in a way similar to the asymmetric centrifugal trap. This magnetic centrifugal mass filter is shown to be more proliferation resistant than present technology. This filter is collisional and produces well confined output streams, among other advantages. __________________________________________________

  2. Effects of rare-earth filters on patient exposure and image contrast

    SciTech Connect

    Mauriello, S.M.; Washburn, D.B.; Matteson, S.R.

    1987-08-01

    Minimizing patient exposure while maintaining a diagnostically acceptable radiograph is a major goal in diagnostic radiography. Rare-earth filters may be the means to achieve this goal due to their band-pass effect. The purpose of this study was to examine the image contrast effects and exposure reductions for various thicknesses of aluminum, samarium, gadolinium, gadolinium oxysulfide, and gadolinium oxysulfide added to 2.5 mm of aluminum. Trials were conducted on an intra-oral dental x-ray unit (range, 65 to 90 kVp). When compared with conventional aluminum, all of the rare-earth filters provided lower radiation exposures, with gadolinium in the metallic or oxysulfide form providing the lowest exposures. Samarium, at a thickness of 0.127 mm, yielded the highest image contrast. Gadolinium or gadolinium oxysulfide added to 2.5 mm of aluminum resulted in a slight loss of contrast when compared with conventional aluminum filtration. This loss may not be clinically significant, and when coupled with the reduced exposure afforded by these filters, they become viable as acceptable alternatives to aluminum filtration.

  3. Application-Dedicated Selection of Filters (ADSF) using covariance maximization and orthogonal projection.

    PubMed

    Hadoux, Xavier; Kumar, Dinesh Kant; Sarossy, Marc G; Roger, Jean-Michel; Gorretta, Nathalie

    2016-05-19

    Visible and near-infrared (Vis-NIR) spectra are generated by the combination of numerous low resolution features. Spectral variables are thus highly correlated, which can cause problems for selecting the most appropriate ones for a given application. Some decomposition bases such as Fourier or wavelet generally help highlighting spectral features that are important, but are by nature constraint to have both positive and negative components. Thus, in addition to complicating the selected features interpretability, it impedes their use for application-dedicated sensors. In this paper we have proposed a new method for feature selection: Application-Dedicated Selection of Filters (ADSF). This method relaxes the shape constraint by enabling the selection of any type of user defined custom features. By considering only relevant features, based on the underlying nature of the data, high regularization of the final model can be obtained, even in the small sample size context often encountered in spectroscopic applications. For larger scale deployment of application-dedicated sensors, these predefined feature constraints can lead to application specific optical filters, e.g., lowpass, highpass, bandpass or bandstop filters with positive only coefficients. In a similar fashion to Partial Least Squares, ADSF successively selects features using covariance maximization and deflates their influences using orthogonal projection in order to optimally tune the selection to the data with limited redundancy. ADSF is well suited for spectroscopic data as it can deal with large numbers of highly correlated variables in supervised learning, even with many correlated responses. PMID:27126785

  4. Quantitative fluorescence detection of phenylalanine in blood spots on filter paper

    NASA Astrophysics Data System (ADS)

    Li, Yuezhi; Liu, Fengjun; Wang, Xuemin; Xu, Gang

    2007-11-01

    Phenylketonuria is a genetic disease, which causes the metabolization disorder of phenylalanine, this disorder would damage the neural system of infants as a result of the accumulation of phenylalanine in blood. Therefore, it is of great importance to diagnose and treat phenylketonuria as early as possible for newborns. The aim of this paper is to develop a fluorescence detection system to measure blood phenylalanine concentration of new-born infants. In this design, a high luminance ultraviolet LED is used for excitation source, and a kind of bifurcated optical fiber assembly is applied for conduction of light. The excitation source is filtered and coupled into quartz fibers of the bifurcated fiber assembly for conduction of light to excite the fluorescence of phenylalanine in blood sample. The collected fluorescence is transmitted along the glass fibers of the assemblies and coupled to a photomultiplier tube. The fluorescence is filtered with 470~500 nm band-pass filter to subdue scattered excitation light and to limit the spectral width of the detected fluorescence. By the comparison with a standard instrument, the new system with low power consumption, low cost and small size is also proven sensitive and accurate, which meets the demand of clinical phenylketonuria screening.

  5. Filtered cathodic arc source

    DOEpatents

    Falabella, Steven; Sanders, David M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45.degree. to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  6. Filtered cathodic arc source

    DOEpatents

    Falabella, S.; Sanders, D.M.

    1994-01-18

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45[degree] to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures.

  7. Filtered cathodic arc source

    SciTech Connect

    Falabella, S.; Sanders, D.M.

    1992-12-31

    Disclosed is a continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45{degrees} to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

  8. Drilling fluid filter

    DOEpatents

    Hall, David R.; Fox, Joe; Garner, Kory

    2007-01-23

    A drilling fluid filter for placement within a bore wall of a tubular drill string component comprises a perforated receptacle with an open end and a closed end. A hanger for engagement with the bore wall is mounted at the open end of the perforated receptacle. A mandrel is adjacent and attached to the open end of the perforated receptacle. A linkage connects the mandrel to the hanger. The linkage may be selected from the group consisting of struts, articulated struts and cams. The mandrel operates on the hanger through the linkage to engage and disengage the drilling fluid filter from the tubular drill string component. The mandrel may have a stationary portion comprising a first attachment to the open end of the perforated receptacle and a telescoping adjustable portion comprising a second attachment to the linkage. The mandrel may also comprise a top-hole interface for top-hole equipment.

  9. Dichroic ultraviolet light filters

    NASA Astrophysics Data System (ADS)

    Kocher, Christoph; Weder, Christoph; Smith, Paul

    2003-10-01

    With the intention to produce dichroic filters for use in photoluminescent systems that rely on polarized UV light, we synthesized a number of linear, dichroic dyes, which absorb mainly in the near-UV range of the electromagnetic spectrum. These dyes were designed for compatibility with common thermoplastic polymers such as linear low-density poly(ethylene), poly(ethylene terephthalate), and polyamide-12. Films of these host polymers that consisted of 0.2% by weight of various dichroic UV dyes were produced by common melt-processing schemes. Uniaxial drawing of these films yielded highly dichroic UV filters with dichroic ratios in absorption that in some cases exceeded 100. The fact that these free-standing films display little or no coloration and are environmentally stable makes them useful for various applications that involve generation of polarized UV light.

  10. High frequency integrated MOS filters

    NASA Technical Reports Server (NTRS)

    Peterson, C.

    1990-01-01

    Several techniques exist for implementing integrated MOS filters. These techniques fit into the general categories of sampled and tuned continuous-time filters. Advantages and limitations of each approach are discussed. This paper focuses primarily on the high frequency capabilities of MOS integrated filters.

  11. Drive Diagnostic Filter Wheel Control

    Energy Science and Technology Software Center (ESTSC)

    2007-07-17

    DrD Filter Wheel Control is National Instrument's Labview software that drives a Drive Diagnostic filter wheel. The software can drive the filter wheel between each end limit, detect the positive and negative limit and each home position and post the stepper motot values to an Excel spreadsheet. The software can also be used to cycle the assembly between the end limits.

  12. Assessment of ceramic membrane filters

    SciTech Connect

    Ahluwalia, R.K.; Geyer, H.K.; Im, K.H.

    1995-08-01

    The objectives of this project include the development of analytical models for evaluating the fluid mechanics of membrane coated, dead-end ceramic filters, and to determine the effects of thermal and thermo-chemical aging on the material properties of emerging ceramic hot gas filters. A honeycomb cordierite monolith with a thin ceramic coating and a rigid candle filter were evaluated.

  13. Quick-change filter cartridge

    DOEpatents

    Rodgers, John C.; McFarland, Andrew R.; Ortiz, Carlos A.

    1995-01-01

    A quick-change filter cartridge. In sampling systems for measurement of airborne materials, a filter element is introduced into the sampled airstream such that the aerosol constituents are removed and deposited on the filter. Fragile sampling media often require support in order to prevent rupture during sampling, and careful mounting and sealing to prevent misalignment, tearing, or creasing which would allow the sampled air to bypass the filter. Additionally, handling of filter elements may introduce cross-contamination or exposure of operators to toxic materials. Moreover, it is desirable to enable the preloading of filter media into quick-change cartridges in clean laboratory environments, thereby simplifying and expediting the filter-changing process in the field. The quick-change filter cartridge of the present invention permits the application of a variety of filter media in many types of instruments and may also be used in automated systems. The cartridge includes a base through which a vacuum can be applied to draw air through the filter medium which is located on a porous filter support and held there by means of a cap which forms an airtight seal with the base. The base is also adapted for receiving absorbing media so that both particulates and gas-phase samples may be trapped for investigation, the latter downstream of the aerosol filter.

  14. BMP FILTERS: UPFLOW VS. DOWNFLOW

    EPA Science Inventory

    Stormwater filters are typically operated in a downflow mode. This research had two objectives: 1) to determine the increased life of a filter operated in an upflow mode, and 2) to determine if the operation of a downflow, mixed-media filter could be modeled using the power equat...

  15. Ultraviolet band-pass Schottky barrier photodetectors formed by Al-doped ZnO contacts to n-GaN

    SciTech Connect

    Sheu, J.K.; Lee, M.L.; Tun, C.J.; Lin, S.W.

    2006-01-23

    This work prepared Al-doped ZnO(AZO) films using dc sputtering to form Schottky contacts onto GaN films with low-temperature-grown GaN cap layer. Application of ultraviolet photodetector showed that spectral responsivity exhibits a narrow bandpass characteristic ranging from 345 to 375 nm. Moreover, unbiased peak responsivity was estimated to be around 0.12 A/W at 365 nm, which corresponds to a quantum efficiency of around 40%. In our study, relatively low responsivity can be explained by the marked absorption of the AZO contact layer. When the reverse biases were below 5 V, the study revealed that dark currents were well below 5x10{sup -12} A even though the samples were annealed at increased temperatures.

  16. Regenerable particulate filter

    DOEpatents

    Stuecker, John N.; Cesarano, III, Joseph; Miller, James E.

    2009-05-05

    A method of making a three-dimensional lattice structure, such as a filter used to remove particulates from a gas stream, where the physical lattice structure is designed utilizing software simulation from pre-defined mass transfer and flow characteristics and the designed lattice structure is fabricated using a free-form fabrication manufacturing technique, where the periodic lattice structure is comprised of individual geometric elements.

  17. Archimedes Mass Filter Vaporizer

    NASA Astrophysics Data System (ADS)

    Putvinski, S.; Agnew, A. F.; Cluggish, B. P.; Ohkawa, T.; Sevier, L.; Umstadter, K. R.; Dresvin, S. V.; Kuteev, B. V.; Feygenson, O. N.; Ivanov, D. V.; Zverev, S. G.; Miroshnikov, I. V.; Egorov, S. M.; Kiesewetter, D. V.; Maliugin, V. I.

    2001-10-01

    Archimedes Technology Group, Inc., is developing a plasma mass separator called the Archimedes Filter that separates waste oxide mixtures ion by ion into two mass groups: light and heavy. Since high-level waste at Hanford has 99.9its radioactivity associated with heavy elements, the Archimedes Filter can effectively decontaminate over three-quarters of that waste. The Filter process involves some preprocessing followed by volatilization and separation by the magnetic and electric fields of the main plasma. This presentation describes the approach to volatilization of the waste oxy-hydroxide mixture by means of a very high heat flux (q > 10 MW/m2). Such a high heat flux is required to ensure congruent evaporation of the complex oxy-hydroxide mixture and is achieved by injection of small droplets of molten waste into an inductively coupled plasma (ICP) torch. This presentation further addresses different issues related to evaporation of the waste including modeling of droplet evaporation, estimates of parameters of plasma torch, and 2D modeling of the plasma. The experimental test bed for oxide vaporization and results of the initial experiments on oxide evaporation in 60 kW ICP torch will also be described.

  18. Improvement in birefringent filters. IV - The alternate partial polarizer filter

    NASA Technical Reports Server (NTRS)

    Title, A. M.

    1976-01-01

    The design and performance of a birefringent filter with alternate partial polarizers are analyzed. The properties of several filter configurations with imperfect intermediate polarizers are examined. It is shown that such filters have significant advantages in transmission and profile shape over both the standard Lyot and the contrast element Lyot filters. These theoretical advantages are demonstrated by the measured properties of an actual filter using the alternate partial polarizer (APP) design. This filter is a four-module eight-crystal APP device which has been built using Polaroid HN-38 for the perfect polarizers and two laminated sheets of HN-55 for the partial polarizers. The measured characteristics of the filter are found to be in good agreement with theory.

  19. Parameter optimization for a high-order band-pass continuous-time sigma-delta modulator MEMS gyroscope using a genetic algorithm approach

    NASA Astrophysics Data System (ADS)

    Chen, Fang; Chang, Honglong; Yuan, Weizheng; Wilcock, Reuben; Kraft, Michael

    2012-10-01

    This paper describes a novel multiobjective parameter optimization method based on a genetic algorithm (GA) for the design of a sixth-order continuous-time, force feedback band-pass sigma-delta modulator (BP-ΣΔM) interface for the sense mode of a MEMS gyroscope. The design procedure starts by deriving a parameterized Simulink model of the BP-ΣΔM gyroscope interface. The system parameters are then optimized by the GA. Consequently, the optimized design is tested for robustness by a Monte Carlo analysis to find a solution that is both optimal and robust. System level simulations result in a signal-to-noise ratio (SNR) larger than 90 dB in a bandwidth of 64 Hz with a 200° s-1 angular rate input signal; the noise floor is about -100 dBV Hz-1/2. The simulations are compared to measured data from a hardware implementation. For zero input rotation with the gyroscope operating at atmospheric pressure, the spectrum of the output bitstream shows an obvious band-pass noise shaping and a deep notch at the gyroscope resonant frequency. The noise floor of measured power spectral density (PSD) of the output bitstream agrees well with simulation of the optimized system level model. The bias stability, rate sensitivity and nonlinearity of the gyroscope controlled by an optimized BP-ΣΔM closed-loop interface are 34.15° h-1, 22.3 mV °-1 s-1, 98 ppm, respectively. This compares to a simple open-loop interface for which the corresponding values are 89° h-1, 14.3 mV °-1 s-1, 7600 ppm, and a nonoptimized BP-ΣΔM closed-loop interface with corresponding values of 60° h-1, 17 mV °-1 s-1, 200 ppm.

  20. COBE experience with filter QUEST

    NASA Astrophysics Data System (ADS)

    Filla, O.; Keat, J.; Chu, D.

    1991-10-01

    A gyro based filter variation on the standard QUEST attitude determination algorithm is applied to the Cosmic Background Explorer (COBE). Filter QUEST is found to be three times as fast as the batch estimator and slightly more accurate than regular QUEST. Perhaps more important than its speed or accuracy is the fact that Filter QUEST can provide real time attitude solutions when regular QUEST cannot, due to lack of observability. Filter QUEST is also easy to use and adjust for the proper memory length. Suitable applications for Filter QUEST include coarse and real time attitude determination.