40 CFR 141.562 - My system only has two or fewer filters-is there any special provision regarding individual...

Code of Federal Regulations, 2013 CFR

2013-07-01

... filters-is there any special provision regarding individual filter turbidity monitoring? 141.562 Section... Fewer Than 10,000 People Individual Filter Turbidity Requirements § 141.562 My system only has two or fewer filters—is there any special provision regarding individual filter turbidity monitoring? Yes, if...

On-board multicarrier demodulator for mobile applications using DSP implementation

NASA Astrophysics Data System (ADS)

Yim, W. H.; Kwan, C. C. D.; Coakley, F. P.; Evans, B. G.

1990-11-01

This paper describes the design and implementation of an on-board multicarrier demodulator using commercial digital signal processors. This is for use in a mobile satellite communication system employing an up-link SCPC/FDMA scheme. Channels are separated by a flexible multistage digital filter bank followed by a channel multiplexed digital demodulator array. The cross/dot product design approach of error detector leads to a new QPSK frequency control algorithm that allows fast acquisition without special preamble pattern. Timing correction is performed digitally using an extended stack of polyphase sub-filters.

Ultrasound image filtering using the mutiplicative model

NASA Astrophysics Data System (ADS)

Navarrete, Hugo; Frery, Alejandro C.; Sanchez, Fermin; Anto, Joan

2002-04-01

Ultrasound images, as a special case of coherent images, are normally corrupted with multiplicative noise i.e. speckle noise. Speckle noise reduction is a difficult task due to its multiplicative nature, but good statistical models of speckle formation are useful to design adaptive speckle reduction filters. In this article a new statistical model, emerging from the Multiplicative Model framework, is presented and compared to previous models (Rayleigh, Rice and K laws). It is shown that the proposed model gives the best performance when modeling the statistics of ultrasound images. Finally, the parameters of the model can be used to quantify the extent of speckle formation; this quantification is applied to adaptive speckle reduction filter design. The effectiveness of the filter is demonstrated on typical in-vivo log-compressed B-scan images obtained by a clinical ultrasound system.

40 CFR 141.564 - My system practices lime softening-is there any special provision regarding my individual filter...

Code of Federal Regulations, 2011 CFR

2011-07-01

... there any special provision regarding my individual filter turbidity monitoring? 141.564 Section 141.564... People Individual Filter Turbidity Requirements § 141.564 My system practices lime softening—is there any special provision regarding my individual filter turbidity monitoring? If your system utilizes lime...

40 CFR 141.564 - My system practices lime softening-is there any special provision regarding my individual filter...

Code of Federal Regulations, 2014 CFR

2014-07-01

... there any special provision regarding my individual filter turbidity monitoring? 141.564 Section 141.564... People Individual Filter Turbidity Requirements § 141.564 My system practices lime softening—is there any special provision regarding my individual filter turbidity monitoring? If your system utilizes lime...

40 CFR 141.564 - My system practices lime softening-is there any special provision regarding my individual filter...

Code of Federal Regulations, 2010 CFR

2010-07-01

... there any special provision regarding my individual filter turbidity monitoring? 141.564 Section 141.564... People Individual Filter Turbidity Requirements § 141.564 My system practices lime softening—is there any special provision regarding my individual filter turbidity monitoring? If your system utilizes lime...

40 CFR 141.564 - My system practices lime softening-is there any special provision regarding my individual filter...

Code of Federal Regulations, 2013 CFR

2013-07-01

... there any special provision regarding my individual filter turbidity monitoring? 141.564 Section 141.564... People Individual Filter Turbidity Requirements § 141.564 My system practices lime softening—is there any special provision regarding my individual filter turbidity monitoring? If your system utilizes lime...

40 CFR 141.564 - My system practices lime softening-is there any special provision regarding my individual filter...

Code of Federal Regulations, 2012 CFR

2012-07-01

... there any special provision regarding my individual filter turbidity monitoring? 141.564 Section 141.564... People Individual Filter Turbidity Requirements § 141.564 My system practices lime softening—is there any special provision regarding my individual filter turbidity monitoring? If your system utilizes lime...

Photographic Film Image Enhancement

DOT National Transportation Integrated Search

1975-01-01

A series of experiments were undertaken to assess the feasibility of defogging color film by the techniques of Optical Spatial Filtering. A coherent optical processor was built using red, blue, and green laser light input and specially designed Fouri...

40 CFR 141.553 - My system practices lime softening-is there any special provision regarding my combined filter...

Code of Federal Regulations, 2014 CFR

2014-07-01

... there any special provision regarding my combined filter effluent? 141.553 Section 141.553 Protection of... Filter Effluent Requirements § 141.553 My system practices lime softening—is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may acidify...

40 CFR 141.553 - My system practices lime softening-is there any special provision regarding my combined filter...

Code of Federal Regulations, 2013 CFR

2013-07-01

... there any special provision regarding my combined filter effluent? 141.553 Section 141.553 Protection of... Filter Effluent Requirements § 141.553 My system practices lime softening—is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may acidify...

40 CFR 141.553 - My system practices lime softening-is there any special provision regarding my combined filter...

Code of Federal Regulations, 2012 CFR

2012-07-01

... there any special provision regarding my combined filter effluent? 141.553 Section 141.553 Protection of... Filter Effluent Requirements § 141.553 My system practices lime softening—is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may acidify...

40 CFR 141.553 - My system practices lime softening-is there any special provision regarding my combined filter...

Code of Federal Regulations, 2010 CFR

2010-07-01

... there any special provision regarding my combined filter effluent? 141.553 Section 141.553 Protection of... Filter Effluent Requirements § 141.553 My system practices lime softening—is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may acidify...

40 CFR 141.553 - My system practices lime softening-is there any special provision regarding my combined filter...

Code of Federal Regulations, 2011 CFR

2011-07-01

... there any special provision regarding my combined filter effluent? 141.553 Section 141.553 Protection of... Filter Effluent Requirements § 141.553 My system practices lime softening—is there any special provision regarding my combined filter effluent? If your system practices lime softening, you may acidify...

XAPiir: A recursive digital filtering package

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

Harris, D.

1990-09-21

XAPiir is a basic recursive digital filtering package, containing both design and implementation subroutines. XAPiir was developed for the experimental array processor (XAP) software package, and is written in FORTRAN. However, it is intended to be incorporated into any general- or special-purpose signal analysis program. It replaces the older package RECFIL, offering several enhancements. RECFIL is used in several large analysis programs developed at LLNL, including the seismic analysis package SAC, several expert systems (NORSEA and NETSEA), and two general purpose signal analysis packages (SIG and VIEW). This report is divided into two sections: the first describes the use ofmore » the subroutine package, and the second, its internal organization. In the first section, the filter design problem is briefly reviewed, along with the definitions of the filter design parameters and their relationship to the subroutine input parameters. In the second section, the internal organization is documented to simplify maintenance and extensions to the package. 5 refs., 9 figs.« less

Structured FBG filters for 10-Gb/s DPSK signal demodulation in single ended applications

NASA Astrophysics Data System (ADS)

Marazzi, L.; Boffi, P.; Parolari, P.; Martinelli, M.; Gatti, D.; Coluccelli, N.; Longhi, S.

2011-05-01

Differential phase-shift keying (DPSK) demodulations operated by a structured fiber Bragg grating (FBG) filter and by a Mach-Zehnder delay interferometer (MZDI) in a single-ended configuration are compared. Experimental measurements at 10 Gb/s demonstrate that a specially designed FBG outperforms an integrated-optic MZDI of ˜4 dB and ˜3.5 dB in back-to-back and after 25-km propagation, respectively. Both demodulators show low polarization sensitivity and signal frequency detuning dependence, but only MZDI operating point requires a thermal control. FBG filter proves an interesting solution for DPSK demodulation in low-cost applications and, moreover, can be designed to match colorless requirements of wave division multiplexed passive optical network (WDM-PON) applications.

Method for mercury refinement

DOEpatents

Grossman, M.W.; Speer, R.; George, W.A.

1991-04-09

The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

Apparatus for mercury refinement

DOEpatents

Grossman, M.W.; Speer, R.; George, W.A.

1991-07-16

The effluent from mercury collected during the photochemical separation of the [sup 196]Hg isotope is often contaminated with particulate mercurous chloride, Hg[sub 2]Cl[sub 2]. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg[sub 2]Cl[sub 2] contaminant. The present invention is particularly directed to such filtering. 5 figures.

Apparatus for mercury refinement

DOEpatents

Grossman, Mark W.; Speer, Richard; George, William A.

1991-01-01

The effluent from mercury collected during the photochemical separation of the .sup.196 Hg isotope is often contaminated with particulate mercurous chloride, Hg.sub.2 Cl.sub.2. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg.sub.2 Cl.sub.2 contaminant. The present invention is particularly directed to such filtering.

Method for mercury refinement

DOEpatents

Grossman, Mark W.; Speer, Richard; George, William A.

1991-01-01

The effluent from mercury collected during the photochemical separation of the .sup.196 Hg isotope is often contaminated with particulate mercurous chloride, Hg.sub.2 Cl.sub.2. The use of mechanical filtering via thin glass tubes, ultrasonic rinsing with acetone (dimethyl ketone) and a specially designed cold trap have been found effective in removing the particulate (i.e., solid) Hg.sub.2 Cl.sub.2 contaminant. The present invention is particularly directed to such filtering.

A Custom Robotic System for Inspecting HEPA Filters in the Payload Changeout Room at the NASA Kennedy Space Center

NASA Technical Reports Server (NTRS)

Spencer, James E., Jr.; Looney, Joe

1994-01-01

In this paper, the prime objective is to describe a custom 4-dof (degree-of-freedom) robotic arm capable of autonomously or telerobotically performing systematic HEPA filter inspection and certification in the Shuttle Launch Pad Payload Changeout Rooms (PCR's) on pads A and B at the Kennedy Space Center, Florida. This HEPA filter inspection robot (HFIR) has been designed to be easily deployable and is equipped with the necessary sensory devices, control hardware, software and man-machine interfaces needed to implement HEPA filter inspection reliably and efficiently without damaging the filters or colliding with existing PCR structures or filters. The main purpose of the HFIR is to implement an automated positioning system to move special inspection sensors in pre-defined or manual patterns for the purpose of verifying filter integrity and efficiency. This will ultimately relieve NASA Payload Operations from significant problems associated with time, cost and personnel safety, impacts realized during non-automated PCR HFIR filter certification.

Direct filtration for recovery of Schistosoma mansoni cercariae in the field.

PubMed

Sandt, D G

1973-01-01

The recovery of schistosome cercariae from natural waters has been limited by variations in turbidity and in the accuracy of recovery with different techniques. A modification of the Rowan vacuum paper filtration method employing a battery-operated pumping system, a glass-silicone plate filter, and a specially designed filter holder is described and evaluated. Field tests on St Lucia indicate a mean filtration volume of 12.2 litres per filter at a mean turbidity of 20.3 Jackson turbidity units. Overall, 86% of the volumes filtered per filter were in excess of 6 litres. Particle size, rather than turbidity, was found to be the main factor influencing filter blockage, reading time, and accuracy. Recoveries of 0.01 cercaria (Schistosoma mansoni) per litre sampled were obtained, but the practical limit of the method is considered to be closer to 0.1 cercaria per litre sampled.

Modal Filters for Infrared Interferometry

NASA Technical Reports Server (NTRS)

Ksendzov, Alexander; MacDonald, Daniel R.; Soibel, Alexander

2009-01-01

Modal filters in the approximately equal to 10-micrometer spectral range have been implemented as planar dielectric waveguides in infrared interferometric applications such as searching for Earth-like planets. When looking for a small, dim object ("Earth") in close proximity to a large, bright object ("Sun"), the interferometric technique uses beams from two telescopes combined with a 180 phase shift in order to cancel the light from a brighter object. The interferometer baseline can be adjusted so that, at the same time, the light from the dimmer object arrives at the combiner in phase. This light can be detected and its infrared (IR) optical spectra can be studied. The cancellation of light from the "Sun" to approximately equal to 10(exp 6) is required; this is not possible without special devices-modal filters- that equalize the wavefronts arriving from the two telescopes. Currently, modal filters in the approximately equal to 10-micrometer spectral range are implemented as single- mode fibers. Using semiconductor technology, single-mode waveguides for use as modal filters were fabricated. Two designs were implemented: one using an InGaAs waveguide layer matched to an InP substrate, and one using InAlAs matched to an InP substrate. Photon Design software was used to design the waveguides, with the main feature all designs being single-mode operation in the 10.5- to 17-micrometer spectral range. Preliminary results show that the filter's rejection ratio is 26 dB.

Basic Electronics II.

ERIC Educational Resources Information Center

Willison, Neal A.; Shelton, James K.

Designed for use in basic electronics programs, this curriculum guide is comprised of 15 units of instruction. Unit titles are Review of the Nature of Matter and the P-N Junction, Rectifiers, Filters, Special Semiconductor Diodes, Bipolar-Junction Diodes, Bipolar Transistor Circuits, Transistor Amplifiers, Operational Amplifiers, Logic Devices,…

Research on starlight hardware-in-the-loop simulator

NASA Astrophysics Data System (ADS)

Zhang, Ying; Gao, Yang; Qu, Huiyang; Liu, Dongfang; Du, Huijie; Lei, Jie

2016-10-01

The starlight navigation is considered to be one of the most important methods for spacecraft navigation. Starlight simulation system is a high-precision system with large fields of view, designed to test the starlight navigation sensor performance on the ground. A complete hardware-in-the-loop simulation of the system has been built. The starlight simulator is made up of light source, light source controller, light filter, LCD, collimator and control computer. LCD is the key display component of the system, and is installed at the focal point of the collimator. For the LCD cannot emit light itself, so light source and light source power controller is specially designed for the brightness demanded by the LCD. Light filter is designed for the dark background which is also needed in the simulation.

Fourier plane filters

NASA Technical Reports Server (NTRS)

Oliver, D. S.; Aldrich, R. E.; Krol, F. T.

1972-01-01

An electrically addressed liquid crystal Fourier plane filter capable of real time optical image processing is described. The filter consists of two parts: a wedge filter having forty 9 deg segments and a ring filter having twenty concentric rings in a one inch diameter active area. Transmission of the filter in the off (transparent) state exceeds fifty percent. By using polarizing optics, contrast as high as 10,000:1 can be achieved at voltages compatible with FET switching technology. A phenomenological model for the dynamic scattering is presented for this special case. The filter is designed to be operated from a computer and is addressed by a seven bit binary word which includes an on or off command and selects any one of the twenty rings or twenty wedge pairs. The overall system uses addressable latches so that once an element is in a specified state, it will remain there until a change of state command is received. The drive for the liquid crystal filter is ? 30 V peak at 30 Hz to 70 Hz. These parameters give a rise time for the scattering of 20 msec and a decay time of 80 to 100 msec.

Educating Smokers about Their Cigarettes and Nicotine Medications

ERIC Educational Resources Information Center

Bansal-Travers, Maansi; Cummings, K. Michael; Hyland, Andrew; Brown, Anthony; Celestino, Paula

2010-01-01

The objective of this study was to test the efficacy of specially designed educational materials to correct misperceptions held by smokers about nicotine, nicotine medications, low tar cigarettes, filters and product ingredients. To accomplish this, 682 New York State Smokers' Quitline callers were randomized to one of two groups: control group…

Fiber Bragg grating inscription in optical multicore fibers

NASA Astrophysics Data System (ADS)

Becker, Martin; Elsmann, Tino; Lorenz, Adrian; Spittel, Ron; Kobelke, Jens; Schuster, Kay; Rothhardt, Manfred; Latka, Ines; Dochow, Sebastian; Bartelt, Hartmut

2015-09-01

Fiber Bragg gratings as key components in telecommunication, fiber lasers, and sensing systems usually rely on the Bragg condition for single mode fibers. In special applications, such as in biophotonics and astrophysics, high light coupling efficiency is of great importance and therefore, multimode fibers are often preferred. The wavelength filtering effect of Bragg gratings in multimode fibers, however is spectrally blurred over a wide modal spectrum of the fiber. With a well-designed all solid multicore microstructured fiber a good light guiding efficiency in combination with narrow spectral filtering effect by Bragg gratings becomes possible.

Aerosolization Characteristics of Hard Impact Testing of Depleted Uranium Penetrators

DTIC Science & Technology

1982-10-01

meters (8 feet) deep half-cylinder, which is designed to prevent sabot parts from travelling laterally after impaction. The PFT is located about 15...specially designed , cut and perforated collection filter. Configuration I is used for staces one and three while Configuration II is used for stages two...official Department of the Army position, unless so designated by other authorized documents. d0#8 Wt oWnsti~tute indo?.dment of an ome, I producot

Evaluation of environmental filtration control of engineered nanoparticles using the Harvard Versatile Engineered Nanomaterial Generation System (VENGES)

NASA Astrophysics Data System (ADS)

Tsai, Candace S.-J.; Echevarría-Vega, Manuel E.; Sotiriou, Georgios A.; Santeufemio, Christopher; Schmidt, Daniel; Demokritou, Philip; Ellenbecker, Michael

2012-05-01

Applying engineering controls to airborne engineered nanoparticles (ENPs) is critical to prevent environmental releases and worker exposure. This study evaluated the effectiveness of two air sampling and six air cleaning fabric filters at collecting ENPs using industrially relevant flame-made engineered nanoparticles generated using a versatile engineered nanomaterial generation system (VENGES), recently designed and constructed at Harvard University. VENGES has the ability to generate metal and metal oxide exposure atmospheres while controlling important particle properties such as primary particle size, aerosol size distribution, and agglomeration state. For this study, amorphous SiO2 ENPs with a 15.4 nm primary particle size were generated and diluted with HEPA-filtered air. The aerosol was passed through the filter samples at two different filtration face velocities (2.3 and 3.5 m/min). Particle concentrations as a function of particle size were measured upstream and downstream of the filters using a specially designed filter test system to evaluate filtration efficiency. Real time instruments (FMPS and APS) were used to measure particle concentration for diameters from 5 to 20,000 nm. Membrane-coated fabric filters were found to have enhanced nanoparticle collection efficiency by 20-46 % points compared to non-coated fabric and could provide collection efficiency above 95 %.

Evaluation of environmental filtration control of engineered nanoparticles using the Harvard Versatile Engineered Nanomaterial Generation System (VENGES)

PubMed Central

Echevarría-Vega, Manuel E.; Sotiriou, Georgios A.; Santeufemio, Christopher; Schmidt, Daniel; Demokritou, Philip; Ellenbecker, Michael

2013-01-01

Applying engineering controls to airborne engineered nanoparticles (ENPs) is critical to prevent environmental releases and worker exposure. This study evaluated the effectiveness of two air sampling and six air cleaning fabric filters at collecting ENPs using industrially relevant flame-made engineered nanoparticles generated using a versatile engineered nanomaterial generation system (VENGES), recently designed and constructed at Harvard University. VENGES has the ability to generate metal and metal oxide exposure atmospheres while controlling important particle properties such as primary particle size, aerosol size distribution, and agglomeration state. For this study, amorphous SiO2 ENPs with a 15.4 nm primary particle size were generated and diluted with HEPA-filtered air. The aerosol was passed through the filter samples at two different filtration face velocities (2.3 and 3.5 m/min). Particle concentrations as a function of particle size were measured upstream and downstream of the filters using a specially designed filter test system to evaluate filtration efficiency. Real time instruments (FMPS and APS) were used to measure particle concentration for diameters from 5 to 20,000 nm. Membrane-coated fabric filters were found to have enhanced nanoparticle collection efficiency by 20–46 % points compared to non-coated fabric and could provide collection efficiency above 95 %. PMID:23412707

What is the best reference RNA? And other questions regarding the design and analysis of two-color microarray experiments.

PubMed

Kerr, Kathleen F; Serikawa, Kyle A; Wei, Caimiao; Peters, Mette A; Bumgarner, Roger E

2007-01-01

The reference design is a practical and popular choice for microarray studies using two-color platforms. In the reference design, the reference RNA uses half of all array resources, leading investigators to ask: What is the best reference RNA? We propose a novel method for evaluating reference RNAs and present the results of an experiment that was specially designed to evaluate three common choices of reference RNA. We found no compelling evidence in favor of any particular reference. In particular, a commercial reference showed no advantage in our data. Our experimental design also enabled a new way to test the effectiveness of pre-processing methods for two-color arrays. Our results favor using intensity normalization and foregoing background subtraction. Finally, we evaluate the sensitivity and specificity of data quality filters, and we propose a new filter that can be applied to any experimental design and does not rely on replicate hybridizations.

Use of astronomy filters in fluorescence microscopy.

PubMed

Piper, Jörg

2012-02-01

Monochrome astronomy filters are well suited for use as excitation or suppression filters in fluorescence microscopy. Because of their particular optical design, such filters can be combined with standard halogen light sources for excitation in many fluorescent probes. In this "low energy excitation," photobleaching (fading) or other irritations of native specimens are avoided. Photomicrographs can be taken from living motile fluorescent specimens also with a flash so that fluorescence images can be created free from indistinctness caused by movement. Special filter cubes or dichroic mirrors are not needed for our method. By use of suitable astronomy filters, fluorescence microscopy can be carried out with standard laboratory microscopes equipped with condensers for bright-field (BF) and dark-field (DF) illumination in transmitted light. In BF excitation, the background brightness can be modulated in tiny steps up to dark or black. Moreover, standard industry microscopes fitted with a vertical illuminator for examinations of opaque probes in DF or BF illumination based on incident light (wafer inspections, for instance) can also be used for excitation in epi-illumination when adequate astronomy filters are inserted as excitatory and suppression filters in the illuminating and imaging light path. In all variants, transmission bands can be modulated by transmission shift.

Two-Dimensional Hermite Filters Simplify the Description of High-Order Statistics of Natural Images.

PubMed

Hu, Qin; Victor, Jonathan D

2016-09-01

Natural image statistics play a crucial role in shaping biological visual systems, understanding their function and design principles, and designing effective computer-vision algorithms. High-order statistics are critical for conveying local features, but they are challenging to study - largely because their number and variety is large. Here, via the use of two-dimensional Hermite (TDH) functions, we identify a covert symmetry in high-order statistics of natural images that simplifies this task. This emerges from the structure of TDH functions, which are an orthogonal set of functions that are organized into a hierarchy of ranks. Specifically, we find that the shape (skewness and kurtosis) of the distribution of filter coefficients depends only on the projection of the function onto a 1-dimensional subspace specific to each rank. The characterization of natural image statistics provided by TDH filter coefficients reflects both their phase and amplitude structure, and we suggest an intuitive interpretation for the special subspace within each rank.

Luma-chroma space filter design for subpixel-based monochrome image downsampling.

PubMed

Fang, Lu; Au, Oscar C; Cheung, Ngai-Man; Katsaggelos, Aggelos K; Li, Houqiang; Zou, Feng

2013-10-01

In general, subpixel-based downsampling can achieve higher apparent resolution of the down-sampled images on LCD or OLED displays than pixel-based downsampling. With the frequency domain analysis of subpixel-based downsampling, we discover special characteristics of the luma-chroma color transform choice for monochrome images. With these, we model the anti-aliasing filter design for subpixel-based monochrome image downsampling as a human visual system-based optimization problem with a two-term cost function and obtain a closed-form solution. One cost term measures the luminance distortion and the other term measures the chrominance aliasing in our chosen luma-chroma space. Simulation results suggest that the proposed method can achieve sharper down-sampled gray/font images compared with conventional pixel and subpixel-based methods, without noticeable color fringing artifacts.

Investigation on the reflector/moderator geometry and its effect on the neutron beam design in BNCT.

PubMed

Kasesaz, Y; Rahmani, F; Khalafi, H

2015-12-01

In order to provide an appropriate neutron beam for Boron Neutron Capture Therapy (BNCT), a special Beam Shaping Assembly (BSA) must be designed based on the neutron source specifications. A typical BSA includes moderator, reflector, collimator, thermal neutron filter, and gamma filter. In common BSA, the reflector is considered as a layer which covers the sides of the moderator materials. In this paper, new reflector/moderator geometries including multi-layer and hexagonal lattice have been suggested and the effect of them has been investigated by MCNP4C Monte Carlo code. It was found that the proposed configurations have a significant effect to improve the thermal to epithermal neutron flux ratio which is an important neutron beam parameter. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pass-band reconfigurable spoof surface plasmon polaritons

NASA Astrophysics Data System (ADS)

Zhang, Hao Chi; He, Pei Hang; Gao, Xinxin; Tang, Wen Xuan; Cui, Tie Jun

2018-04-01

In this paper, we introduce a new scheme to construct the band-pass tunable filter based on the band-pass reconfigurable spoof surface plasmon polaritons (SPPs), whose cut-off frequencies at both sides of the passband can be tuned through changing the direct current (DC) bias of varactors. Compared to traditional technology (e.g. microstrip filters), the spoof SPP structure can provide more tight field confinement and more significant field enhancement, which is extremely valuable for many system applications. In order to achieve this scheme, we proposed a specially designed SPP filter integrated with varactors and DC bias feeding structure to support the spoof SPP passband reconfiguration. Furthermore, the full-wave simulated result verifies the outstanding performance on both efficiency and reconfiguration, which has the potential to be widely used in advanced intelligent systems.

A miniaturized HTS microwave receiver front-end subsystem for radar and communication applications

NASA Astrophysics Data System (ADS)

Bian, Yongbo; Guo, Jin; Gao, Changzheng; Li, Chunguang; Li, Hong; Wang, Jia; Cui, Bin; He, Xiaofeng; Li, Chao; Li, Na; Li, Guoqiang; Zhang, Qiang; Zhang, Xueqiang; Meng, Jibao; He, Yusheng

2010-08-01

This paper presents a miniaturized high performance high temperature superconducting (HTS) microwave receiver front-end subsystem, which uses a mini stirling cryocooler to cool a high selective HTS filter and a low noise amplifier (LNA). The HTS filter was miniaturized by using specially designed compact resonators and fabricating with double-sided YBCO films on LAO substrate which has a relatively high permittivity. The LNA was specially designed to work at cryogenic temperature with noise figure of 0.27 dB at 71 K. The mini cryocooler, which is widely used in infrared detectors, has a smaller size (60 mm × 80 mm × 100 mm) and a lighter weight (340 g) than the stirling cryocoolers commonly used in other HTS filter subsystem. The whole front-end subsystem, including a HTS filter, a LNA, a cryocooler and the vacuum chamber, has a size of only φ120 mm × 175 mm and a weight of only 3.3 kg. The microwave devices inside the subsystem are working at 71.8 K with a consumed cooling power of 0.325 W. The center frequency of this subsystem is 925.2 MHz and the bandwidth is 2.7 MHz (which is a fractional bandwidth of 0.2%), with the gain of 19.75 dB at center frequency and the return loss better than -18.11 dB in the pass band. The stop band rejection is more than 60 dB and the skirt slope is exceeding 120 dB MHz -1. The noise figure of this subsystem is less than 0.8 dB. This front-end subsystem can be used in radars and communication systems conveniently due to it’s compact size and light weight.

Design of Circular, Square, Single, and Multi-layer Induction Coils for Electromagnetic Priming Using Inductance Estimates

NASA Astrophysics Data System (ADS)

Fritzsch, Robert; Kennedy, Mark W.; Aune, Ragnhild E.

2018-02-01

Special induction coils used for electro magnetic priming of ceramic foam filters in liquid metal filtration have been designed using a combination of analytical and finite element modeling. Relatively simple empirical equations published by Wheeler in 1928 and 1982 have been used during the design process. The equations were found to accurately predict the z-component of the magnetic flux densities of both single- and multi-layer coils as verified both experimentally and by using COMSOL® 5.1 multiphysics simulations.

Steep and flat bandpass filter using linearly chirped and apodized fiber Bragg grating

NASA Astrophysics Data System (ADS)

Wu, Xunqi; Jacquet, Jo"l.; Duan, Guanghua

2010-02-01

The development of new optical systems requires the design of novel components that fulfill the market constraints. In particular, low loss, high optical rejection and low cost narrowband filters can play an important role for the introduction of the Wavelength Division Multiplexing (WDM) technology in the local network. So, a novel fiber filter is proposed in this article, with a special combined apodized Linearly Chirped Fiber Bragg Grating (LCFBG) which presents the preferable flat-top and steep-edge characteristics. In the design, we use a continuum cavity condition which is obtained when the effective round-trip phase of oscillated wavelength band is kept identical over the whole Bragg wavelength range. And the transmission spectra are calculated by the reconstruction of the matrixes with the continuum oscillation condition. Therefore, our works show that the ideal square shaped filter is obtained with a lower chirp value relatively together with symmetric reflectivity on both mirrors. The coupling coefficient of the FBG is adjusted to get the same reflectivity values and then to get a transmission filter close to unity. We have then introduced an apodization function of the filter to get a flatter transfer function. Various apodizations schemes have been tested. In this paper, we design and analyze a type of continuum fiber filter with the cavity formed between mirror and apodized LCFBG as reflectors. We calculate firstly the reflectivity, the transmissivity and the group time delay of LCFBG modeled by a simple and practical Transfer Matrix Method (TMM), and then the cavity is reconstructed by TMM, the length of the oscillated cavity is calculated by the continuum oscillation condition, so the output of transmission from the side of LCFBG is continuous in the corresponded reflected bandwidth of LCFBG. We obtain the results and discuss some characteristics of this type of continuum fiber filter.

Recursive least squares method of regression coefficients estimation as a special case of Kalman filter

NASA Astrophysics Data System (ADS)

Borodachev, S. M.

2016-06-01

The simple derivation of recursive least squares (RLS) method equations is given as special case of Kalman filter estimation of a constant system state under changing observation conditions. A numerical example illustrates application of RLS to multicollinearity problem.

Design of a 32-Channel EEG System for Brain Control Interface Applications

PubMed Central

Wang, Ching-Sung

2012-01-01

This study integrates the hardware circuit design and the development support of the software interface to achieve a 32-channel EEG system for BCI applications. Since the EEG signals of human bodies are generally very weak, in addition to preventing noise interference, it also requires avoiding the waveform distortion as well as waveform offset and so on; therefore, the design of a preamplifier with high common-mode rejection ratio and high signal-to-noise ratio is very important. Moreover, the friction between the electrode pads and the skin as well as the design of dual power supply will generate DC bias which affects the measurement signals. For this reason, this study specially designs an improved single-power AC-coupled circuit, which effectively reduces the DC bias and improves the error caused by the effects of part errors. At the same time, the digital way is applied to design the adjustable amplification and filter function, which can design for different EEG frequency bands. For the analog circuit, a frequency band will be taken out through the filtering circuit and then the digital filtering design will be used to adjust the extracted frequency band for the target frequency band, combining with MATLAB to design man-machine interface for displaying brain wave. Finally the measured signals are compared to the traditional 32-channel EEG signals. In addition to meeting the IFCN standards, the system design also conducted measurement verification in the standard EEG isolation room in order to demonstrate the accuracy and reliability of this system design. PMID:22778545

Design of a 32-channel EEG system for brain control interface applications.

PubMed

Wang, Ching-Sung

2012-01-01

This study integrates the hardware circuit design and the development support of the software interface to achieve a 32-channel EEG system for BCI applications. Since the EEG signals of human bodies are generally very weak, in addition to preventing noise interference, it also requires avoiding the waveform distortion as well as waveform offset and so on; therefore, the design of a preamplifier with high common-mode rejection ratio and high signal-to-noise ratio is very important. Moreover, the friction between the electrode pads and the skin as well as the design of dual power supply will generate DC bias which affects the measurement signals. For this reason, this study specially designs an improved single-power AC-coupled circuit, which effectively reduces the DC bias and improves the error caused by the effects of part errors. At the same time, the digital way is applied to design the adjustable amplification and filter function, which can design for different EEG frequency bands. For the analog circuit, a frequency band will be taken out through the filtering circuit and then the digital filtering design will be used to adjust the extracted frequency band for the target frequency band, combining with MATLAB to design man-machine interface for displaying brain wave. Finally the measured signals are compared to the traditional 32-channel EEG signals. In addition to meeting the IFCN standards, the system design also conducted measurement verification in the standard EEG isolation room in order to demonstrate the accuracy and reliability of this system design.

Electron volt spectroscopy on a pulsed neutron source

NASA Astrophysics Data System (ADS)

Newport, R. J.; Penfold, J.; Williams, W. G.

1984-07-01

The principal design aspects of a pulsed source neutron spectrometer in which the scattered neutron energy is determined by a resonance absorption filter difference method are discussed. Calculations of the accessible dynamic range, resolution and spectrum simulations are given for the spectrometer on a high intensity pulsed neutron source, such as the spallation neutron source (SNS) now being constructed at the Rutherford Appleton Laboratory. Special emphasis is made of the advantage gained by placing coarse and fixed energy-sensitive filters before and after the scatterer; these enhance the inelastic/elastic descrimination of the method. A brief description is given of a double difference filter method which gives a superior difference peak shape, as well as a better energy transfer resolution. Finally, some first results of scattering from zirconium hydride, obtained on a test spectrometer, are presented.

A Bio-Realistic Analog CMOS Cochlea Filter With High Tunability and Ultra-Steep Roll-Off.

PubMed

Wang, Shiwei; Koickal, Thomas Jacob; Hamilton, Alister; Cheung, Rebecca; Smith, Leslie S

2015-06-01

This paper presents the design and experimental results of a cochlea filter in analog very large scale integration (VLSI) which highly resembles physiologically measured response of the mammalian cochlea. The filter consists of three specialized sub-filter stages which respectively provide passive response in low frequencies, actively tunable response in mid-band frequencies and ultra-steep roll-off at transition frequencies from pass-band to stop-band. The sub-filters are implemented in balanced ladder topology using floating active inductors. Measured results from the fabricated chip show that wide range of mid-band tuning including gain tuning of over 20 dB, Q factor tuning from 2 to 19 as well as the bio-realistic center frequency shift are achieved by adjusting only one circuit parameter. Besides, the filter has an ultra-steep roll-off reaching over 300 dB/dec. By changing biasing currents, the filter can be configured to operate with center frequencies from 31 Hz to 8 kHz. The filter is 9th order, consumes 59.5 ∼ 90.0 μW power and occupies 0.9 mm2 chip area. A parallel bank of the proposed filter can be used as the front-end in hearing prosthesis devices, speech processors as well as other bio-inspired auditory systems owing to its bio-realistic behavior, low power consumption and small size.

Low-cost space-varying FIR filter architecture for computational imaging systems

NASA Astrophysics Data System (ADS)

Feng, Guotong; Shoaib, Mohammed; Schwartz, Edward L.; Dirk Robinson, M.

2010-01-01

Recent research demonstrates the advantage of designing electro-optical imaging systems by jointly optimizing the optical and digital subsystems. The optical systems designed using this joint approach intentionally introduce large and often space-varying optical aberrations that produce blurry optical images. Digital sharpening restores reduced contrast due to these intentional optical aberrations. Computational imaging systems designed in this fashion have several advantages including extended depth-of-field, lower system costs, and improved low-light performance. Currently, most consumer imaging systems lack the necessary computational resources to compensate for these optical systems with large aberrations in the digital processor. Hence, the exploitation of the advantages of the jointly designed computational imaging system requires low-complexity algorithms enabling space-varying sharpening. In this paper, we describe a low-cost algorithmic framework and associated hardware enabling the space-varying finite impulse response (FIR) sharpening required to restore largely aberrated optical images. Our framework leverages the space-varying properties of optical images formed using rotationally-symmetric optical lens elements. First, we describe an approach to leverage the rotational symmetry of the point spread function (PSF) about the optical axis allowing computational savings. Second, we employ a specially designed bank of sharpening filters tuned to the specific radial variation common to optical aberrations. We evaluate the computational efficiency and image quality achieved by using this low-cost space-varying FIR filter architecture.

Nonequal iteration directional filters permit selective clearance of ripples in passband circuits

NASA Technical Reports Server (NTRS)

Kurpis, G. P.

1970-01-01

Modified directional filter is comprised of alternate pairs of dielectric and air gap filter sections with unequal electrical lengths. Filter provides more flexibility in choosing dielectric material thickness and permits switching from specially ground to standard thicknesses.

A Low Cost Structurally Optimized Design for Diverse Filter Types

PubMed Central

Kazmi, Majida; Aziz, Arshad; Akhtar, Pervez; Ikram, Nassar

2016-01-01

A wide range of image processing applications deploys two dimensional (2D)-filters for performing diversified tasks such as image enhancement, edge detection, noise suppression, multi scale decomposition and compression etc. All of these tasks require multiple type of 2D-filters simultaneously to acquire the desired results. The resource hungry conventional approach is not a viable option for implementing these computationally intensive 2D-filters especially in a resource constraint environment. Thus it calls for optimized solutions. Mostly the optimization of these filters are based on exploiting structural properties. A common shortcoming of all previously reported optimized approaches is their restricted applicability only for a specific filter type. These narrow scoped solutions completely disregard the versatility attribute of advanced image processing applications and in turn offset their effectiveness while implementing a complete application. This paper presents an efficient framework which exploits the structural properties of 2D-filters for effectually reducing its computational cost along with an added advantage of versatility for supporting diverse filter types. A composite symmetric filter structure is introduced which exploits the identities of quadrant and circular T-symmetries in two distinct filter regions simultaneously. These T-symmetries effectually reduce the number of filter coefficients and consequently its multipliers count. The proposed framework at the same time empowers this composite filter structure with additional capabilities of realizing all of its Ψ-symmetry based subtypes and also its special asymmetric filters case. The two-fold optimized framework thus reduces filter computational cost up to 75% as compared to the conventional approach as well as its versatility attribute not only supports diverse filter types but also offers further cost reduction via resource sharing for sequential implementation of diversified image processing applications especially in a constraint environment. PMID:27832133

Parallelized Kalman-Filter-Based Reconstruction of Particle Tracks on Many-Core Processors and GPUs

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

Cerati, Giuseppe; Elmer, Peter; Krutelyov, Slava

2017-01-01

For over a decade now, physical and energy constraints have limited clock speed improvements in commodity microprocessors. Instead, chipmakers have been pushed into producing lower-power, multi-core processors such as Graphical Processing Units (GPU), ARM CPUs, and Intel MICs. Broad-based efforts from manufacturers and developers have been devoted to making these processors user-friendly enough to perform general computations. However, extracting performance from a larger number of cores, as well as specialized vector or SIMD units, requires special care in algorithm design and code optimization. One of the most computationally challenging problems in high-energy particle experiments is finding and fitting the charged-particlemore » tracks during event reconstruction. This is expected to become by far the dominant problem at the High-Luminosity Large Hadron Collider (HL-LHC), for example. Today the most common track finding methods are those based on the Kalman filter. Experience with Kalman techniques on real tracking detector systems has shown that they are robust and provide high physics performance. This is why they are currently in use at the LHC, both in the trigger and offine. Previously we reported on the significant parallel speedups that resulted from our investigations to adapt Kalman filters to track fitting and track building on Intel Xeon and Xeon Phi. Here, we discuss our progresses toward the understanding of these processors and the new developments to port the Kalman filter to NVIDIA GPUs.« less

Parallelized Kalman-Filter-Based Reconstruction of Particle Tracks on Many-Core Processors and GPUs

NASA Astrophysics Data System (ADS)

Cerati, Giuseppe; Elmer, Peter; Krutelyov, Slava; Lantz, Steven; Lefebvre, Matthieu; Masciovecchio, Mario; McDermott, Kevin; Riley, Daniel; Tadel, Matevž; Wittich, Peter; Würthwein, Frank; Yagil, Avi

2017-08-01

For over a decade now, physical and energy constraints have limited clock speed improvements in commodity microprocessors. Instead, chipmakers have been pushed into producing lower-power, multi-core processors such as Graphical Processing Units (GPU), ARM CPUs, and Intel MICs. Broad-based efforts from manufacturers and developers have been devoted to making these processors user-friendly enough to perform general computations. However, extracting performance from a larger number of cores, as well as specialized vector or SIMD units, requires special care in algorithm design and code optimization. One of the most computationally challenging problems in high-energy particle experiments is finding and fitting the charged-particle tracks during event reconstruction. This is expected to become by far the dominant problem at the High-Luminosity Large Hadron Collider (HL-LHC), for example. Today the most common track finding methods are those based on the Kalman filter. Experience with Kalman techniques on real tracking detector systems has shown that they are robust and provide high physics performance. This is why they are currently in use at the LHC, both in the trigger and offine. Previously we reported on the significant parallel speedups that resulted from our investigations to adapt Kalman filters to track fitting and track building on Intel Xeon and Xeon Phi. Here, we discuss our progresses toward the understanding of these processors and the new developments to port the Kalman filter to NVIDIA GPUs.

Photographic film image enhancement

NASA Technical Reports Server (NTRS)

Horner, J. L.

1975-01-01

A series of experiments were undertaken to assess the feasibility of defogging color film by the techniques of optical spatial filtering. A coherent optical processor was built using red, blue, and green laser light input and specially designed Fourier transformation lenses. An array of spatial filters was fabricated on black and white emulsion slides using the coherent optical processor. The technique was first applied to laboratory white light fogged film, and the results were successful. However, when the same technique was applied to some original Apollo X radiation fogged color negatives, the results showed no similar restoration. Examples of each experiment are presented and possible reasons for the lack of restoration in the Apollo films are discussed.

A dense grid of narrow bandpass steep edge filters for the JST/T250 telescope: summary of results

NASA Astrophysics Data System (ADS)

Brauneck, U.; Sprengard, R.; Bourquin, S.; Marín-Franch, A.

2017-09-01

On the Javalambre mountain in Spain, the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA) has setup a new wide field telescope, the JST/T250: a 2.55 m telescope with a plate scale of 22.67"/mm and a 3° diameter field of view. To conduct a photometric sky survey, a large format mosaic camera made of 14 individual CCDs is used in combination with filter trays containing 14 filters each of theses 101.7 x 96.5 mm in size. For this instrument, SCHOTT manufactured 56 specially designed steep edged bandpass interference filters which were recently completed. The filter set consists of bandpass filters in the range between 348,5 nm and 910 nm and a longpass filter at 915 nm. Most of the filters have FWHM of 14.5 nm and a blocking between 250 and 1050 nm with optical density of OD5. Absorptive color glass substrates in combination with interference filters were used to minimize residual reflection in order to avoid ghost images. Inspite of containing absorptive elements, the filters show the maximum possible transmission. This was achieved by using magnetron sputtering for the filter coating process. The most important requirement for the continuous photometric survey is the tight tolerancing of the central wavelengths and FWHM of the filters. This insures each bandpass having a defined overlap with its neighbors. In addition, the blocking of the filters is better than OD5 in the range 250-1050 nm. A high image quality required a low transmitted wavefront error (

Eyes Matched to the Prize: The State of Matched Filters in Insect Visual Circuits.

PubMed

Kohn, Jessica R; Heath, Sarah L; Behnia, Rudy

2018-01-01

Confronted with an ever-changing visual landscape, animals must be able to detect relevant stimuli and translate this information into behavioral output. A visual scene contains an abundance of information: to interpret the entirety of it would be uneconomical. To optimally perform this task, neural mechanisms exist to enhance the detection of important features of the sensory environment while simultaneously filtering out irrelevant information. This can be accomplished by using a circuit design that implements specific "matched filters" that are tuned to relevant stimuli. Following this rule, the well-characterized visual systems of insects have evolved to streamline feature extraction on both a structural and functional level. Here, we review examples of specialized visual microcircuits for vital behaviors across insect species, including feature detection, escape, and estimation of self-motion. Additionally, we discuss how these microcircuits are modulated to weigh relevant input with respect to different internal and behavioral states.

Spatial filtering of audible sound with acoustic landscapes

NASA Astrophysics Data System (ADS)

Wang, Shuping; Tao, Jiancheng; Qiu, Xiaojun; Cheng, Jianchun

2017-07-01

Acoustic metasurfaces manipulate waves with specially designed structures and achieve properties that natural materials cannot offer. Similar surfaces work in audio frequency range as well and lead to marvelous acoustic phenomena that can be perceived by human ears. Being intrigued by the famous Maoshan Bugle phenomenon, we investigate large scale metasurfaces consisting of periodic steps of sizes comparable to the wavelength of audio frequency in both time and space domains. We propose a theoretical method to calculate the scattered sound field and find that periodic corrugated surfaces work as spatial filters and the frequency selective character can only be observed at the same side as the incident wave. The Maoshan Bugle phenomenon can be well explained with the method. Finally, we demonstrate that the proposed method can be used to design acoustical landscapes, which transform impulsive sound into famous trumpet solos or other melodious sound.

On VLSI Design of Rank-Order Filtering using DCRAM Architecture

PubMed Central

Lin, Meng-Chun; Dung, Lan-Rong

2009-01-01

This paper addresses on VLSI design of rank-order filtering (ROF) with a maskable memory for real-time speech and image processing applications. Based on a generic bit-sliced ROF algorithm, the proposed design uses a special-defined memory, called the dual-cell random-access memory (DCRAM), to realize major operations of ROF: threshold decomposition and polarization. Using the memory-oriented architecture, the proposed ROF processor can benefit from high flexibility, low cost and high speed. The DCRAM can perform the bit-sliced read, partial write, and pipelined processing. The bit-sliced read and partial write are driven by maskable registers. With recursive execution of the bit-slicing read and partial write, the DCRAM can effectively realize ROF in terms of cost and speed. The proposed design has been implemented using TSMC 0.18 μm 1P6M technology. As shown in the result of physical implementation, the core size is 356.1 × 427.7μm2 and the VLSI implementation of ROF can operate at 256 MHz for 1.8V supply. PMID:19865599

Efficiency of automotive cabin air filters to reduce acute health effects of diesel exhaust in human subjects

PubMed Central

Rudell, B.; Wass, U.; Horstedt, P.; Levin, J. O.; Lindahl, R.; Rannug, U.; Sunesson, A. L.; Ostberg, Y.; Sandstrom, T.

1999-01-01

OBJECTIVES: To evaluate the efficiency of different automotive cabin air filters to prevent penetration of components of diesel exhaust and thereby reduce biomedical effects in human subjects. Filtered air and unfiltered diluted diesel exhaust (DDE) were used as negative and positive controls, respectively, and were compared with exposure to DDE filtered with four different filter systems. METHODS: 32 Healthy non- smoking subjects (age 21-53) participated in the study. Each subject was exposed six times for 1 hour in a specially designed exposure chamber: once to air, once to unfiltered DDE, and once to DDE filtered with the four different cabin air filters. Particle concentrations during exposure to unfiltered DDE were kept at 300 micrograms/m3. Two of the filters were particle filters. The other two were particle filters combined with active charcoal filters that might reduce certain gaseous components. Subjective symptoms were recorded and nasal airway lavage (NAL), acoustic rhinometry, and lung function measurements were performed. RESULTS: The two particle filters decreased the concentrations of diesel exhaust particles by about half, but did not reduce the intensity of symptoms induced by exhaust. The combination of active charcoal filters and a particle filter significantly reduced the symptoms and discomfort caused by the diesel exhaust. The most noticable differences in efficacy between the filters were found in the reduction of detection of an unpleasant smell from the diesel exhaust. In this respect even the two charcoal filter combinations differed significantly. The efficacy to reduce symptoms may depend on the abilities of the filters investigated to reduce certain hydrocarbons. No acute effects on NAL, rhinometry, and lung function variables were found. CONCLUSIONS: This study has shown that the use of active charcoal filters, and a particle filter, clearly reduced the intensity of symptoms induced by diesel exhaust. Complementary studies on vehicle cabin air filters may result in further diminishing the biomedical effects of diesel exhaust in subjects exposed in traffic and workplaces.   PMID:10450238

Frequency tuning characteristics of a Q-switched Co:MgF2 laser

NASA Technical Reports Server (NTRS)

Lovold, S.; Moulton, P. F.; Killinger, D. K.; Menyuk, N.

1985-01-01

A tunable Q-switched Co:MgF2 laser has been developed for atmospheric remote sensing applications. Frequency tuning is provided by a quartz etalon and a specially designed three-element birefringent filter covering the whole gain bandwidth of the Co:MgF2 laser. The laser has good temporal and spectral characteristics, with an emission linewidth of approximately 3 GHz (0.1 per cm).

Video image processing

NASA Technical Reports Server (NTRS)

Murray, N. D.

1985-01-01

Current technology projections indicate a lack of availability of special purpose computing for Space Station applications. Potential functions for video image special purpose processing are being investigated, such as smoothing, enhancement, restoration and filtering, data compression, feature extraction, object detection and identification, pixel interpolation/extrapolation, spectral estimation and factorization, and vision synthesis. Also, architectural approaches are being identified and a conceptual design generated. Computationally simple algorithms will be research and their image/vision effectiveness determined. Suitable algorithms will be implimented into an overall architectural approach that will provide image/vision processing at video rates that are flexible, selectable, and programmable. Information is given in the form of charts, diagrams and outlines.

Characterizations of Some Fuzzy Prefilters (Filters) in EQ-Algebras

PubMed Central

Xin, Xiao Long; Yang, Yong Wei

2014-01-01

We introduce and study some types of fuzzy prefilters (filters) in EQ-algebras. First, we present several characterizations of fuzzy positive implicative prefilters (filters), fuzzy implicative prefilters (filters), and fuzzy fantastic prefilters (filters). Next, using their characterizations, we mainly consider the relationships among these special fuzzy filters. Particularly, we find some conditions under which a fuzzy implicative prefilter (filter) is equivalent to a fuzzy positive implicative prefilter (filter). As applications, we obtain some new results about classical filters in EQ-algebras and some related results about fuzzy filters in residuated lattices. PMID:24892096

Customized broadband sloan-filters for the JST/T250 and JAST/T80 telescopes: summary of results

NASA Astrophysics Data System (ADS)

Brauneck, U.; Sprengard, R.; Bourquin, S.; Marín-Franch, A.

2017-09-01

The Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA) will conduct a photometric sky survey with 2 new telescopes recently setup on the Javalambre mountain in Spain: the JST/T250 is a 2.55m telescope with a plate scale of 22.67"/mm and a 3° diameter field of view (FoV) and the auxiliary telescope JAST/T80 with a 82cm primary mirror and a FoV of 2 deg diameter. A multiple CCD (9k-by-9k array size, 10μm pixel size) mosaic camera is used in combination with filter trays or filter wheels, each containing a multitude of filters in dimensions of 101.7x96.5mm or 106.8x106.8mm. For this project, SCHOTT manufactured 56 specially designed narrow band steep edged bandpass interference filters and 5 broadband sloan-filters which were completed only recently. We report here on the results of the broadband sloanfilters with transmission bands of 324-400nm (sloan-u), 400-550nm (sloan-g), 550-700nm (sloan-r), 695-850nm (sloan-i) and 830-1200nm (sloan-z). The filters are composed of SCHOTT filterglasses and clearglass substrates coated with interference filters and represent an improvement of broadband sloan filters commonly used in astronomy. Inspite of the absorptive elements, the filters show maximum possible transmissions achieved by magnetron sputtered filter coatings. In addition the blocking of the filters is better than OD5 in the range 250-1050nm. A high image quality required a low transmitted wavefront error (<λ/8 locally, respectively <λ/2 globally) which was achieved by combining up to 2 substrates. We report on the spectral and interferometric results measured on the filters.

Determination of Pd, Pt and Rh in vehicles escape fumes by GF-AAS and ICP-OES.

PubMed

Goncalves, Antonio; Domínguez, José R; Alvarado, José

2008-04-15

Automotive exhaust gases from vehicles using catalytic converters were filtered through cellulose filter papers to collect suspended particles expulsed along with the engine's escape fumes. A specially designed sample collector was used for supporting the filter papers during collection. The collector was manufactured from a new car's exhaust pipe. A cellulose circular paper filter, 11 cm diameter, was attached to one end of the pipe and kept centered by pressing it against the borders of the pipe by means of a perforated aluminum cap, slightly wider than the pipe, used to cover this end of the collector. Filter papers loaded with the solid particles were acid-digested using a modified domestic microwave oven to bring the solid material into solution. The resulting solutions were analyzed for Pt by graphite furnace atomic absorption spectrometry (GF-AAS) and for Pd and Rh by inductively coupled plasma (ICP-OES). Results indicate that concentration of these analytes in the particulate is higher for new vehicles, having new catalytic converters, than for old ones. Maximum Pd, Pt and Rh in the samples analyzed were found to be 5.36, 12.60 and 1.03 microg g(-1), respectively.

Ultra-wide bandpass filter based on long-period fiber gratings and the evanescent field coupling between two fibers.

PubMed

Kim, Myoung Jin; Jung, Yong Min; Kim, Bok Hyeon; Han, Won-Taek; Lee, Byeong Ha

2007-08-20

We demonstrate a fiber-based bandpass filter with an ultra-wide spectral bandwidth. The ultra-wide band feature is achieved by inscribing a long-period fiber grating (LPG) in a specially-designed low index core single mode fiber. To get the bandpass function, the evanescent field coupling between two attached fibers is utilized. By applying strain, the spectral shape of the pass-band is adjusted to flat-top and Gaussian shapes. For the flat-top case, the bandwidth is obtained ~ 160 nm with an insertion loss of ~ 2 dB. With strain, the spectral shape is switched into a Gaussian one, which has ~ 120 nm FWHM and ~ 4.18 dB insertion loss at the peak.

Biomedical bandpass filter for fluorescence microscopy imaging based on TiO2/SiO2 and TiO2/MgF2 dielectric multilayers

NASA Astrophysics Data System (ADS)

Butt, M. A.; Fomchenkov, S. A.; Ullah, A.; Verma, P.; Khonina, S. N.

2016-08-01

We report a design for creating a multilayer dielectric optical filters based on TiO2 and SiO2/MgF2 alternating layers. We have selected Titanium dioxide (TiO2) for high refractive index (2.5), Silicon dioxide (SiO2) and Magnesium fluoride (MgF2) as a low refractive index layer (1.45 & 1.37) respectively. Miniaturized visible spectrometers are useful for quick and mobile characterization of biological samples. Such devices can be fabricated by using Fabry-Perot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. Distributed Bragg Reflectors (DBRs) consisting of alternating high and low refractive index material pairs are the most commonly used mirrors in FP filters, due to their high reflectivity. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer range. Therefore a bandpass filters are required to restrict wavelength outside the stopband of the FP DBRs. The proposed filter shows a high quality with average transmission of 97.4% within the passbands and the transmission outside the passband is around 4%. Special attention has been given to keep the thickness of the filters within the economic limits. It can be suggested that these filters are exceptional choice for florescence imaging and Endoscope narrow band imaging.

A Novel Grid SINS/DVL Integrated Navigation Algorithm for Marine Application

PubMed Central

Kang, Yingyao; Zhao, Lin; Cheng, Jianhua; Fan, Xiaoliang

2018-01-01

Integrated navigation algorithms under the grid frame have been proposed based on the Kalman filter (KF) to solve the problem of navigation in some special regions. However, in the existing study of grid strapdown inertial navigation system (SINS)/Doppler velocity log (DVL) integrated navigation algorithms, the Earth models of the filter dynamic model and the SINS mechanization are not unified. Besides, traditional integrated systems with the KF based correction scheme are susceptible to measurement errors, which would decrease the accuracy and robustness of the system. In this paper, an adaptive robust Kalman filter (ARKF) based hybrid-correction grid SINS/DVL integrated navigation algorithm is designed with the unified reference ellipsoid Earth model to improve the navigation accuracy in middle-high latitude regions for marine application. Firstly, to unify the Earth models, the mechanization of grid SINS is introduced and the error equations are derived based on the same reference ellipsoid Earth model. Then, a more accurate grid SINS/DVL filter model is designed according to the new error equations. Finally, a hybrid-correction scheme based on the ARKF is proposed to resist the effect of measurement errors. Simulation and experiment results show that, compared with the traditional algorithms, the proposed navigation algorithm can effectively improve the navigation performance in middle-high latitude regions by the unified Earth models and the ARKF based hybrid-correction scheme. PMID:29373549

The design of wavefront coded imaging system

NASA Astrophysics Data System (ADS)

Lan, Shun; Cen, Zhaofeng; Li, Xiaotong

2016-10-01

Wavefront Coding is a new method to extend the depth of field, which combines optical design and signal processing together. By using optical design software ZEMAX ,we designed a practical wavefront coded imaging system based on a conventional Cooke triplet system .Unlike conventional optical system, the wavefront of this new system is modulated by a specially designed phase mask, which makes the point spread function (PSF)of optical system not sensitive to defocus. Therefore, a series of same blurred images obtained at the image plane. In addition, the optical transfer function (OTF) of the wavefront coded imaging system is independent of focus, which is nearly constant with misfocus and has no regions of zeros. All object information can be completely recovered through digital filtering at different defocus positions. The focus invariance of MTF is selected as merit function in this design. And the coefficients of phase mask are set as optimization goals. Compared to conventional optical system, wavefront coded imaging system obtains better quality images under different object distances. Some deficiencies appear in the restored images due to the influence of digital filtering algorithm, which are also analyzed in this paper. The depth of field of the designed wavefront coded imaging system is about 28 times larger than initial optical system, while keeping higher optical power and resolution at the image plane.

A comparative CFD study of four inferior vena cava filters.

PubMed

López, Josep M; Fortuny, Gerard; Puigjaner, Dolors; Herrero, Joan; Marimon, Francesc

2018-03-30

Computational fluid dynamics was used to simulate the flow of blood within an inferior vena cava (IVC) geometry model that was reconstructed from computed tomography images obtained from a real patient. The main novelty of the present work is that we simulated the implantation of 4 different filter models in this realistic IVC geometry. We considered different blood flow rates in the range between V in =20 and V in =80 cm 3 /s, and all simulations were performed with both the Newtonian and a non-Newtonian model for the blood viscosity. We compared the hemodynamics performance of the different filter models, and we paid a special attention to the total drag force, F d , exerted by the blood flow on the filter surface. This force is the sum of 2 contributions: the viscous skin friction force, which was found to be roughly proportional to the filter surface area, and the pressure force, which depended on the particular filter geometry design. The F d force is relevant because it must be balanced by the total force exerted by the filter hooks/struts on the IVC wall at the attachment locations. For the highest V in value investigated, the variation in F d among filters was from 116 to 308 dyne. We also showed how the present results can be extrapolated to obtain good estimates of the drag forces if the blood viscosity levels change, ie, if the patient with a filter implanted is treated with anticoagulant therapy. Copyright © 2018 John Wiley & Sons, Ltd.

Customized broadband Sloan-filters for the JST/T250 and JAST/T80 telescopes: measurement summary

NASA Astrophysics Data System (ADS)

Brauneck, Ulf; Sprengard, Ruediger; Bourquin, Sebastien; Marín-Franch, Antonio

2018-01-01

The Centro de Estudios de Fisica del Cosmos de Aragon will conduct a photometric sky survey with two new telescopes recently set up on the Javalambre mountain in Spain: the JST/T250 is a 2.55-m telescope with a plate scale of 22.67 arc⁢sec/mm and a 3-deg-diameter field of view (FoV) and the auxiliary telescope JAST/T80 with a 82-cm primary mirror and an FoV of 2 deg diameter. A multiple CCD (9k-by-9k array size, 10-μm pixel size) mosaic camera is used in combination with filter trays or filter wheels, each containing a multitude of filters in dimensions of 101.7×96.5 mm or 106.8×106.8 mm. For this project, Schott manufactured 56 specially designed narrow band steep-edged bandpass interference filters and five broadband Sloan-filters which were completed only recently. We report here on the results of the broadband Sloan-filters with transmission bands of 324 to 400 nm (Sloan-u), 400 to 550 nm (Sloan-g), 550 to 700 nm (Sloan-r), 695 to 850 nm (Sloan-i), and 830 to 1200 nm (Sloan-z). The filters are composed of Schott filterglasses and clearglass substrates coated with interference filters and represent an improvement of broadband Sloan filters commonly used in astronomy. In spite of the absorptive elements, the filters show maximum possible transmissions achieved by magnetron sputtered filter coatings. In addition, the blocking of the filters is better than OD5 (transmission <10 to -5) in the range 250 to 1050 nm which was achieved by combining up to three substrates. A high image quality required a low transmitted wavefront error (<λ/8 locally, respectively <λ/2 globally). We report on the spectral and interferometric results measured on the filters.

Fast spacecraft adaptive attitude tracking control through immersion and invariance design

NASA Astrophysics Data System (ADS)

Wen, Haowei; Yue, Xiaokui; Li, Peng; Yuan, Jianping

2017-10-01

This paper presents a novel non-certainty-equivalence adaptive control method for the attitude tracking control problem of spacecraft with inertia uncertainties. The proposed immersion and invariance (I&I) based adaptation law provides a more direct and flexible approach to circumvent the limitations of the basic I&I method without employing any filter signal. By virtue of the adaptation high-gain equivalence property derived from the proposed adaptive method, the closed-loop adaptive system with a low adaptation gain could recover the high adaptation gain performance of the filter-based I&I method, and the resulting control torque demands during the initial transient has been significantly reduced. A special feature of this method is that the convergence of the parameter estimation error has been observably improved by utilizing an adaptation gain matrix instead of a single adaptation gain value. Numerical simulations are presented to highlight the various benefits of the proposed method compared with the certainty-equivalence-based control method and filter-based I&I control schemes.

An optimal control approach to the design of moving flight simulators

NASA Technical Reports Server (NTRS)

Sivan, R.; Ish-Shalom, J.; Huang, J.-K.

1982-01-01

An abstract flight simulator design problem is formulated in the form of an optimal control problem, which is solved for the linear-quadratic-Gaussian special case using a mathematical model of the vestibular organs. The optimization criterion used is the mean-square difference between the physiological outputs of the vestibular organs of the pilot in the aircraft and the pilot in the simulator. The dynamical equations are linearized, and the output signal is modeled as a random process with rational power spectral density. The method described yields the optimal structure of the simulator's motion generator, or 'washout filter'. A two-degree-of-freedom flight simulator design, including single output simulations, is presented.

Use of Semantic Technology to Create Curated Data Albums

NASA Technical Reports Server (NTRS)

Ramachandran, Rahul; Kulkarni, Ajinkya; Li, Xiang; Sainju, Roshan; Bakare, Rohan; Basyal, Sabin

2014-01-01

One of the continuing challenges in any Earth science investigation is the discovery and access of useful science content from the increasingly large volumes of Earth science data and related information available online. Current Earth science data systems are designed with the assumption that researchers access data primarily by instrument or geophysical parameter. Those who know exactly the data sets they need can obtain the specific files using these systems. However, in cases where researchers are interested in studying an event of research interest, they must manually assemble a variety of relevant data sets by searching the different distributed data systems. Consequently, there is a need to design and build specialized search and discover tools in Earth science that can filter through large volumes of distributed online data and information and only aggregate the relevant resources needed to support climatology and case studies. This paper presents a specialized search and discovery tool that automatically creates curated Data Albums. The tool was designed to enable key elements of the search process such as dynamic interaction and sense-making. The tool supports dynamic interaction via different modes of interactivity and visual presentation of information. The compilation of information and data into a Data Album is analogous to a shoebox within the sense-making framework. This tool automates most of the tedious information/data gathering tasks for researchers. Data curation by the tool is achieved via an ontology-based, relevancy ranking algorithm that filters out nonrelevant information and data. The curation enables better search results as compared to the simple keyword searches provided by existing data systems in Earth science.

Use of Semantic Technology to Create Curated Data Albums

NASA Technical Reports Server (NTRS)

Ramachandran, Rahul; Kulkarni, Ajinkya; Li, Xiang; Sainju, Roshan; Bakare, Rohan; Basyal, Sabin; Fox, Peter (Editor); Norack, Tom (Editor)

2014-01-01

One of the continuing challenges in any Earth science investigation is the discovery and access of useful science content from the increasingly large volumes of Earth science data and related information available online. Current Earth science data systems are designed with the assumption that researchers access data primarily by instrument or geophysical parameter. Those who know exactly the data sets they need can obtain the specific files using these systems. However, in cases where researchers are interested in studying an event of research interest, they must manually assemble a variety of relevant data sets by searching the different distributed data systems. Consequently, there is a need to design and build specialized search and discovery tools in Earth science that can filter through large volumes of distributed online data and information and only aggregate the relevant resources needed to support climatology and case studies. This paper presents a specialized search and discovery tool that automatically creates curated Data Albums. The tool was designed to enable key elements of the search process such as dynamic interaction and sense-making. The tool supports dynamic interaction via different modes of interactivity and visual presentation of information. The compilation of information and data into a Data Album is analogous to a shoebox within the sense-making framework. This tool automates most of the tedious information/data gathering tasks for researchers. Data curation by the tool is achieved via an ontology-based, relevancy ranking algorithm that filters out non-relevant information and data. The curation enables better search results as compared to the simple keyword searches provided by existing data systems in Earth science.

Dialysis centers -- what to expect

MedlinePlus

... will flow through a special filter that removes waste and excess fluid. The filter is sometimes called ... on: How well your kidneys work How much waste needs to be removed How much water weight ...

Vision-sensing image analysis for GTAW process control

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

Long, D.D.

1994-11-01

Image analysis of a gas tungsten arc welding (GTAW) process was completed using video images from a charge coupled device (CCD) camera inside a specially designed coaxial (GTAW) electrode holder. Video data was obtained from filtered and unfiltered images, with and without the GTAW arc present, showing weld joint features and locations. Data Translation image processing boards, installed in an IBM PC AT 386 compatible computer, and Media Cybernetics image processing software were used to investigate edge flange weld joint geometry for image analysis.

Simple methods to reduce patient exposure during scoliosis radiography

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

Butler, P.F.; Thomas, A.W.; Thompson, W.E.

1986-05-01

Radiation exposure to the breasts of adolescent females can be reduced significantly through the use of one or all of the following methods: fast, rare-earth screen-film combinations; specially designed compensating filters; and breast shielding. The importance of exposure reduction during scoliosis radiography as well as further details on the above described methods are discussed. In addition, the early results of a Center for Devices and Radiological Health study, which recorded exposure and technique data for scoliosis radiography, is presented.

Dense grid of narrow bandpass filters for the JST/T250 telescope: summary of results

NASA Astrophysics Data System (ADS)

Brauneck, Ulf; Sprengard, Ruediger; Bourquin, Sebastien; Marín-Franch, Antonio

2018-01-01

On the Javalambre mountain in Spain, the Centro de Estudios de Fisica del Cosmos de Aragon has setup two telescopes, the JST/T250 and the JAST/T80. The JAST/T80 telescope integrates T80Cam, a large format, single CCD camera while the JST/T250 will mount the JPCam instrument, a 1.2Gpix camera equipped with a 14-CCD mosaic using the new large format e2v 9.2k×9.2k 10-μm pixel detectors. Both T80Cam and JPCam integrate a large number of filters in dimensions of 106.8×106.8 mm2 and 101.7×95.5 mm2, respectively. For this instrument, SCHOTT manufactured 56 specially designed steep edged bandpass interference filters, which were recently completed. The filter set consists of bandpass filters in the range between 348.5 and 910 nm and a longpass filter at 915 nm. Most of the filters have full-width at half-maximum (FWHM) of 14.5 nm and a blocking between 250 and 1050 nm with optical density of OD5. Absorptive color glass substrates in combination with interference filters were used to minimize residual reflection in order to avoid ghost images. In spite of containing absorptive elements, the filters show the maximum possible transmission. This was achieved by using magnetron sputtering for the filter coating process. The most important requirement for the continuous photometric survey is the tight tolerancing of the central wavelengths and FWHM of the filters. This insures each bandpass has a defined overlap with its neighbors. A high image quality required a low transmitted wavefront error (<λ/4 locally and <λ/2 on the whole aperture), which was achieved even by combining two or three substrates. We report on the spectral and interferometric results measured on the whole set of filters.

FILTSoft: A computational tool for microstrip planar filter design

NASA Astrophysics Data System (ADS)

Elsayed, M. H.; Abidin, Z. Z.; Dahlan, S. H.; Cholan N., A.; Ngu, Xavier T. I.; Majid, H. A.

2017-09-01

Filters are key component of any communication system to control spectrum and suppress interferences. Designing a filter involves long process as well as good understanding of the basic hardware technology. Hence this paper introduces an automated design tool based on Matlab-GUI, called the FILTSoft (acronym for Filter Design Software) to ease the process. FILTSoft is a user friendly filter design tool to aid, guide and expedite calculations from lumped elements level to microstrip structure. Users just have to provide the required filter specifications as well as the material description. FILTSoft will calculate and display the lumped element details, the planar filter structure, and the expected filter's response. An example of a lowpass filter design was calculated using FILTSoft and the results were validated through prototype measurement for comparison purposes.

Lessons Learned in the Development of Gamma-Rover (GRover) Inspection Device

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

Valdez, Patrick LJ; Alzheimer, James M.; Catalan, Michael A.

2006-02-11

The Gamma-Rover (GRover) is an electrically powered crawler designed to visually inspect and characterize the radiological conditions within the B-Cell and D-Cell ventilation ducting in support of the Hanford Site’s 324 Building Stabilization/Deactivation Project. Due to the bid opening of the Department of Energy’s River Corridor Project prior to deployment, GRover has not yet been deployed. The delay in deployment has allowed the designers to develop lessons learned from the original development in order to propose improvements when the system is deployed in the future. Gamma field information is detected with a pair of Eberline DA1-8/RMS systems. One system ismore » mounted directly on the crawler, while the second is mounted on the deployment platform. Four web cameras on a pair of CAT-5e/USB channels provide video feedback from both the crawler and the deployment platform. The drive system was designed to overcome a potentially difficult path of the duct, which included three ninety-degree bends. Mockups of the duct bends yielded high friction on the tether, and a drive system to overcome this friction was especially difficult to design into such a small package. Deployment was to be performed during a routine air filter change-out. As such, a specialized deployment platform was designed to pass through the existing filter housing. GRover would be required to be staged within the hot cell prior to the filter change-out and could therefore be dosed in excess of 8 hours. Thus, the platform also had to protect the electronics from radiation damage for an extended period of time.« less

Design of a composite filter realizable on practical spatial light modulators

NASA Technical Reports Server (NTRS)

Rajan, P. K.; Ramakrishnan, Ramachandran

1994-01-01

Hybrid optical correlator systems use two spatial light modulators (SLM's), one at the input plane and the other at the filter plane. Currently available SLM's such as the deformable mirror device (DMD) and liquid crystal television (LCTV) SLM's exhibit arbitrarily constrained operating characteristics. The pattern recognition filters designed with the assumption that the SLM's have ideal operating characteristic may not behave as expected when implemented on the DMD or LCTV SLM's. Therefore it is necessary to incorporate the SLM constraints in the design of the filters. In this report, an iterative method is developed for the design of an unconstrained minimum average correlation energy (MACE) filter. Then using this algorithm a new approach for the design of a SLM constrained distortion invariant filter in the presence of input SLM is developed. Two different optimization algorithms are used to maximize the objective function during filter synthesis, one based on the simplex method and the other based on the Hooke and Jeeves method. Also, the simulated annealing based filter design algorithm proposed by Khan and Rajan is refined and improved. The performance of the filter is evaluated in terms of its recognition/discrimination capabilities using computer simulations and the results are compared with a simulated annealing optimization based MACE filter. The filters are designed for different LCTV SLM's operating characteristics and the correlation responses are compared. The distortion tolerance and the false class image discrimination qualities of the filter are comparable to those of the simulated annealing based filter but the new filter design takes about 1/6 of the computer time taken by the simulated annealing filter design.

Preprocessing of PHERMEX flash radiographic images with Haar and adaptive filtering

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

Brolley, J.E.

1978-11-01

Work on image preparation has continued with the application of high-sequency boosting via Haar filtering. This is useful in developing line or edge structures. Widrow LMS adaptive filtering has also been shown to be useful in developing edge structure in special problems. Shadow effects can be obtained with the latter which may be useful for some problems. Combined Haar and adaptive filtering is illustrated for a PHERMEX image.

Measuring the Acoustic Release of a Chemotherapeutic Agent from Folate-Targeted Polymeric Micelles.

PubMed

Abusara, Ayah; Abdel-Hafez, Mamoun; Husseini, Ghaleb

2018-08-01

In this paper, we compare the use of Bayesian filters for the estimation of release and re-encapsulation rates of a chemotherapeutic agent (namely Doxorubicin) from nanocarriers in an acoustically activated drug release system. The study is implemented using an advanced kinetic model that takes into account cavitation events causing the antineoplastic agent's release from polymeric micelles upon exposure to ultrasound. This model is an improvement over the previous representations of acoustic release that used simple zero-, first- and second-order release and re-encapsulation kinetics to study acoustically triggered drug release from polymeric micelles. The new model incorporates drug release and micellar reassembly events caused by cavitation allowing for the controlled release of chemotherapeutics specially and temporally. Different Bayesian estimators are tested for this purpose including Kalman filters (KF), Extended Kalman filters (EKF), Particle filters (PF), and multi-model KF and EKF. Simulated and experimental results are used to verify the performance of the above-mentioned estimators. The proposed methods demonstrate the utility and high-accuracy of using estimation methods in modeling this drug delivery technique. The results show that, in both cases (linear and non-linear dynamics), the modeling errors are expensive but can be minimized using a multi-model approach. In addition, particle filters are more flexible filters that perform reasonably well compared to the other two filters. The study improved the accuracy of the kinetic models used to capture acoustically activated drug release from polymeric micelles, which may in turn help in designing hardware and software capable of precisely controlling the delivered amount of chemotherapeutics to cancerous tissue.

Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids

PubMed Central

2012-01-01

We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.) PMID:22515214

Audit filters for improving processes of care and clinical outcomes in trauma systems.

PubMed

Evans, Christopher; Howes, Daniel; Pickett, William; Dagnone, Luigi

2009-10-07

Traumatic injuries represent a considerable public health burden with significant personal and societal costs. The care of the severely injured patient in a trauma system progresses along a continuum that includes numerous interventions being provided by a multidisciplinary group of healthcare personnel. Despite the recent emphasis on quality of care in medicine, there has been little research to direct trauma clinicians and administrators on how optimally to monitor and improve upon the quality of care delivered within a trauma system. Audit filters are one mechanism for improving quality of care and are defined as specific clinical processes or outcomes of care that, when they occur, represent unfavorable deviations from an established norm and which prompt review and feedback. Although audit filters are widely utilized for performance improvement in trauma systems they have not been subjected to systematic review of their effectiveness. To determine the effectiveness of using audit filters for improving processes of care and clinical outcomes in trauma systems. Our search strategy included an electronic search of the Cochrane Injuries Group Specialized Register, the Cochrane EPOC Group Specialized Register, CENTRAL (The Cochrane Library 2008, Issue 4), MEDLINE, PubMed, EMBASE, CINAHL, and ISI Web of Science: (SCI-EXPANDED and CPCI-S). We handsearched the Journal of Trauma, Injury, Annals of Emergency Medicine, Academic Emergency Medicine, and Injury Prevention. We searched two clinical trial registries: 1) The World Health Organization International Clinical Trials Registry Platform and, 2) Clinical Trials.gov. We also contacted content experts for further articles. The most recent electronic search was completed in December 2008 and the handsearch was completed up to February 2009. We searched for randomized controlled trials, controlled clinical trials, controlled before-and-after studies, and interrupted time series studies that used audit filters as an intervention for improving processes of care, morbidity, or mortality for severely injured patients. Two authors independently screened the search results, applied inclusion criteria, and extracted data. There were no studies identified that met the inclusion criteria for this review. We were unable to identify any studies of sufficient methodological quality to draw conclusions regarding the effectiveness of audit filters as a performance improvement intervention in trauma systems. Future research using rigorous study designs should focus on the relative effectiveness of audit filters in comparison to alternative quality improvement strategies at improving processes of care, functional outcomes, and mortality for injured patients.

An RC active filter design handbook

NASA Technical Reports Server (NTRS)

Deboo, G. J.

1977-01-01

The design of filters is described. Emphasis is placed on simplified procedures that can be used by the reader who has minimum knowledge about circuit design and little acquaintance with filter theory. The handbook has three main parts. The first part is a review of some information that is essential for work with filters. The second part includes design information for specific types of filter circuitry and describes simple procedures for obtaining the component values for a filter that will have a desired set of characteristics. Pertinent information relating to actual performance is given. The third part (appendix) is a review of certain topics in filter theory and is intended to provide some basic understanding of how filters are designed.

Penetration of Combustion Aerosol Particles Through Filters of NIOSH-Certified Filtering Facepiece Respirators (FFRs).

PubMed

Gao, Shuang; Kim, Jinyong; Yermakov, Michael; Elmashae, Yousef; He, Xinjian; Reponen, Tiina; Grinshpun, Sergey A

2015-01-01

Filtering facepiece respirators (FFRs) are commonly worn by first responders, first receivers, and other exposed groups to protect against exposure to airborne particles, including those originated by combustion. Most of these FFRs are NIOSH-certified (e.g., N95-type) based on the performance testing of their filters against charge-equilibrated aerosol challenges, e.g., NaCl. However, it has not been examined if the filtration data obtained with the NaCl-challenged FFR filters adequately represent the protection against real aerosol hazards such as combustion particles. A filter sample of N95 FFR mounted on a specially designed holder was challenged with NaCl particles and three combustion aerosols generated in a test chamber by burning wood, paper, and plastic. The concentrations upstream (Cup) and downstream (Cdown) of the filter were measured with a TSI P-Trak condensation particle counter and a Grimm Nanocheck particle spectrometer. Penetration was determined as (Cdown/Cup) ×100%. Four test conditions were chosen to represent inhalation flows of 15, 30, 55, and 85 L/min. Results showed that the penetration values of combustion particles were significantly higher than those of the "model" NaCl particles (p < 0.05), raising a concern about applicability of the N95 filters performance obtained with the NaCl aerosol challenge to protection against combustion particles. Aerosol type, inhalation flow rate and particle size were significant (p < 0.05) factors affecting the performance of the N95 FFR filter. In contrast to N95 filters, the penetration of combustion particles through R95 and P95 FFR filters (were tested in addition to N95) were not significantly higher than that obtained with NaCl particles. The findings were attributed to several effects, including the degradation of an N95 filter due to hydrophobic organic components generated into the air by combustion. Their interaction with fibers is anticipated to be similar to those involving "oily" particles. The findings of this study suggest that the efficiency of N95 respirator filters obtained with the NaCl aerosol challenge may not accurately predict (and rather overestimate) the filter efficiency against combustion particles.

Modern Display Technologies for Airborne Applications.

DTIC Science & Technology

1983-04-01

the case of LED head-down direct view displays, this requires that special attention be paid to the optical filtering , the electrical drive/address...effectively attenuates the LED specular reflectance component, the colour and neutral density filtering attentuate the diffuse component and the... filter techniques are planned for use with video, multi- colour and advanced versions of numeric, alphanumeric and graphic displays; this technique

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.

Application of lead-acrylic compensating filters in chiropractic full spine radiography: a technical report

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

Buehler, M.T.; Hrejsa, A.F.

X-raying the entire spinal column in the standing position in a single exposure (mainly the AP projection) is an often-used chiropractic radiography procedure which has also found some application in medical scoliosis screening program. Aside from any controversy of clinical objectives or medical necessity, the primary agreed-upon requisite for such procedure is twofold; achieving the best possible film image quality with the least amount of radiation exposure to the patient. A popular method of accomplishing this objective is by the use of collimator-attached devices designed to selectively filter the primary x-ray beam in accordance with regional variations of body thicknessmore » and/or density. This study was conducted to evaluate the use of a new lead-acrylic filter system under specialized chiropractic conditions. In comparison to other available systems, it was concluded that this new system; a) is generally equivalent in its radiation dose reduction capabilities; b) is capable of producing full spine radiographs with good to above average image quality; and c) is appreciably easier to use.« less

Commissioning and Science Verification of JAST/T80

NASA Astrophysics Data System (ADS)

Ederoclte, A.; Cenarro, A. J.; Marín-Franch, A.; Cristóbal-Hornillos, D.; Vázquez Ramió, H.; Varela, J.; Hurier, G.; Moles, M.; Lamadrid, J. L.; Díaz-Martín, M. C.; Iglesias Marzoa, R.; Tilve, V.; Rodríguez, S.; Maícas, N.; Abri, J.

2017-03-01

Located at the Observatorio Astrofísico de Javalambre, the ’’Javalambre Auxiliary Survey Telescope’’ is an 80cm telescope with a unvignetted 2 square degrees field of view. The telescope is equipped with T80Cam, a camera with a large format CCD and two filter wheels which can host, at any given time, 12 filters. The telescope has been designed to provide optical quality all across the field of view, which is achieved with a field corrector. In this talk, I will review the commissioning of the telescope. The optical performance in the centre of the field of view has been tested with lucky imaging technique, providing a telescope PSF of 0.4’’, which is close to the one expected from theory. Moreover, the tracking of the telescope does not affect the image quality, as it has been shown that stars appear round even in exposures of 10minutes obtained without guiding. Most importantly, we present the preliminary results of science verification observations which combine the two main characteristics of this telescope: the large field of view and the special filter set.

Phase noise suppression through parametric filtering

NASA Astrophysics Data System (ADS)

Cassella, Cristian; Strachan, Scott; Shaw, Steven W.; Piazza, Gianluca

2017-02-01

In this work, we introduce and experimentally demonstrate a parametric phase noise suppression technique, which we call "parametric phase noise filtering." This technique is based on the use of a solid-state parametric amplifier operating in its instability region and included in a non-autonomous feedback loop connected at the output of a noisy oscillator. We demonstrate that such a system behaves as a parametrically driven Duffing resonator and can operate at special points where it becomes largely immune to the phase fluctuations that affect the oscillator output signal. A prototype of a parametric phase noise filter (PFIL) was designed and fabricated to operate in the very-high-frequency range. The PFIL prototype allowed us to significantly reduce the phase noise at the output of a commercial signal generator operating around 220 MHz. Noise reduction of 16 dB (40×) and 13 dB (20×) were obtained, respectively, at 1 and 10 kHz offsets from the carrier frequency. The demonstration of this phase noise suppression technique opens up scenarios in the development of passive and low-cost phase noise cancellation circuits for any application demanding high quality frequency generation.

Advanced technology satellite demodulator development

NASA Technical Reports Server (NTRS)

Ames, Stephen A.

1989-01-01

Ford Aerospace has developed a proof-of-concept satellite 8 phase shift keying (PSK) modulation and coding system operating in the Time Division Multiple Access (TDMA) mode at a data range of 200 Mbps using rate 5/6 forward error correction coding. The 80 Msps 8 PSK modem was developed in a mostly digital form and is amenable to an ASIC realization in the next phase of development. The codec was developed as a paper design only. The power efficiency goal was to be within 2 dB of theoretical at a bit error rate (BER) of 5x10(exp 7) while the measured implementation loss was 4.5 dB. The bandwidth efficiency goal was 2 bits/sec/Hz while the realized bandwidth efficiency was 1.8 bits/sec/Hz. The burst format used a preamble of only 40 8 PSK symbol times including 32 symbols of all zeros and an eight symbol unique word. The modem and associated special test equipment (STE) were fabricated mostly on a specially designed stitch-weld board although a few of the highest rate circuits were built on printed circuit cards. All the digital circuits were ECL to support the clock rates of from 80 MHz to 360 MHz. The transmitter and receiver matched filters were square-root Nyquist bandpass filters realized at the 3.37 GHz i.f. The modem operated as a coherent system although no analog phase locked (PLL) loop was employed. Within the budgetary constraints of the program, the approach to the demodulator has been proven and is eligible to proceed to the next phase of development of a satellite demodulator engineering model. This would entail the development of an ASIC version of the digital portion of the demodulator, and MMIC version of the quadrature detector, and SAW Nyquist filters to realize the bandwidth efficiency.

An advanced real-time digital signal processing system for linear systems emulation, with special emphasis on network and acoustic response characterization

NASA Astrophysics Data System (ADS)

Gaydecki, Patrick; Fernandes, Bosco

2003-11-01

A fast digital signal processing (DSP) system is described that can perform real-time emulation of a wide variety of linear audio-bandwidth systems and networks, such as reverberant spaces, musical instrument bodies and very high order filter networks. The hardware design is based upon a Motorola DSP56309 operating at 110 million multiplication-accumulations per second and a dual-channel 24 bit codec with a maximum sampling frequency of 192 kHz. High level software has been developed to express complex vector frequency responses as both infinite impulse response (IIR) and finite impulse response (FIR) coefficients, in a form suitable for real-time convolution by the firmware installed in the DSP system memory. An algorithm has also been devised to express IIR filters as equivalent FIR structures, thereby obviating the potential instabilities associated with recursive equations and negating the traditional deficiencies of FIR filters respecting equivalent analogue designs. The speed and dynamic range of the system is such that, when sampling at 48 kHz, the frequency response can be specified to a spectral precision of 22 Hz when sampling at 10 kHz, this resolution increases to 0.9 Hz. Moreover, it is also possible to control the phase of any frequency band with a theoretical precision of 10-5 degrees in all cases. The system has been applied in the study of analogue filter networks, real-time Hilbert transformation, phase-shift systems and musical instrument body emulation, where it is providing valuable new insights into the understanding of psychoacoustic mechanisms.

Performance of a miniature mechanically cooled HPGe gamma-spectrometer for space applications

NASA Astrophysics Data System (ADS)

Kondratjev, V.; Pchelintsev, A.; Jakovlevs, O.; Sokolov, A.; Gostilo, V.; Owens, A.

2018-01-01

We report on the development of a miniaturized HPGe gamma-spectrometer for space applications. The instrument is designed around a 158 cm3 intrinsically pure Ge crystal in the closed-end coaxial configuration, cooled by a Thales RM3 miniature Stirling cycle electric cooler. To compensate the noise induced by the mechanical cooler the digital procession of the spectrometric signals with low frequency reject filter (LFR) is applied. The complete spectrometer assembly has a mass of 3.1 kg and consumes less than 10 W under working operation. The spectrometer was tested under a number of operating conditions in a specially designed chamber, which simulates the space environment. With the mechanical cooler switched off, FWHM energy resolutions of 1.5 keV and 2.2 keV were obtained at 122 keV and 1333 keV, respectively, at the nominal operating temperature of 90 K. When the cooler was switched on the energy resolutions degraded to 2.5 keV and 4 keV respectively. However, with the LFR filter switched in, the resolutions improved significantly to 1.8 keV and 2.4 keV.

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.

Design and implementation of an electrocardiographical signal acquisition and digital processing system orientated to the detection of paroxysmal arrhythmias

NASA Astrophysics Data System (ADS)

Iriart Braceli, Agustín; Exequiel Morani, Jorge

2011-12-01

This article describes the design, technical aspects and implementation of a device capable of acquiring electrocardiograph signals; visualize them in real time over a graphic liquid crystal display (GLCD), and the storage of these ECG registers on a SD memory card. It also details a noise suppression algorithm using the Wavelet Transform. This system was specially developed to cover some bankruptcy that presents actual Holters or ECG regarding the detection of paroxysmal arrhythmias. The contribution of this work is settled on its portability and low production cost. The filtering method used provides an ECG signal without any significant noise and appropriate to the diagnosis of cardiac pathologies.

A Highly Reliable and Cost-Efficient Multi-Sensor System for Land Vehicle Positioning.

PubMed

Li, Xu; Xu, Qimin; Li, Bin; Song, Xianghui

2016-05-25

In this paper, we propose a novel positioning solution for land vehicles which is highly reliable and cost-efficient. The proposed positioning system fuses information from the MEMS-based reduced inertial sensor system (RISS) which consists of one vertical gyroscope and two horizontal accelerometers, low-cost GPS, and supplementary sensors and sources. First, pitch and roll angle are accurately estimated based on a vehicle kinematic model. Meanwhile, the negative effect of the uncertain nonlinear drift of MEMS inertial sensors is eliminated by an H∞ filter. Further, a distributed-dual-H∞ filtering (DDHF) mechanism is adopted to address the uncertain nonlinear drift of the MEMS-RISS and make full use of the supplementary sensors and sources. The DDHF is composed of a main H∞ filter (MHF) and an auxiliary H∞ filter (AHF). Finally, a generalized regression neural network (GRNN) module with good approximation capability is specially designed for the MEMS-RISS. A hybrid methodology which combines the GRNN module and the AHF is utilized to compensate for RISS position errors during GPS outages. To verify the effectiveness of the proposed solution, road-test experiments with various scenarios were performed. The experimental results illustrate that the proposed system can achieve accurate and reliable positioning for land vehicles.

Advanced lithographic filtration and contamination control for 14nm node and beyond semiconductor processes

NASA Astrophysics Data System (ADS)

Varanasi, Rao; Mesawich, Michael; Connor, Patrick; Johnson, Lawrence

2017-03-01

Two versions of a specific 2nm rated filter containing filtration medium and all other components produced from high density polyethylene (HDPE), one subjected to standard cleaning, the other to specialized ultra-cleaning, were evaluated in terms of their cleanliness characteristics, and also defectivity of wafers processed with photoresist filtered through each. With respect to inherent cleanliness, the ultraclean version exhibited a 70% reduction in total metal extractables and 90% reduction in organics extractables compared to the standard clean version. In terms of particulate cleanliness, the ultraclean version achieved stability of effluent particles 30nm and larger in about half the time required by the standard clean version, also exhibiting effluent levels at stability almost 90% lower. In evaluating defectivity of blanket wafers processed with photoresist filtered through either version, initial defect density while using the ultraclean version was about half that observed when the standard clean version was in service, with defectivity also falling more rapidly during subsequent usage of the ultraclean version compared to the standard clean version. Similar behavior was observed for patterned wafers, where the enhanced defect reduction was primarily of bridging defects. The filter evaluation and actual process-oriented results demonstrate the extreme value in using filtration designed possessing the optimal intrinsic characteristics, but with further improvements possible through enhanced cleaning processes

A Highly Reliable and Cost-Efficient Multi-Sensor System for Land Vehicle Positioning

PubMed Central

Li, Xu; Xu, Qimin; Li, Bin; Song, Xianghui

2016-01-01

In this paper, we propose a novel positioning solution for land vehicles which is highly reliable and cost-efficient. The proposed positioning system fuses information from the MEMS-based reduced inertial sensor system (RISS) which consists of one vertical gyroscope and two horizontal accelerometers, low-cost GPS, and supplementary sensors and sources. First, pitch and roll angle are accurately estimated based on a vehicle kinematic model. Meanwhile, the negative effect of the uncertain nonlinear drift of MEMS inertial sensors is eliminated by an H∞ filter. Further, a distributed-dual-H∞ filtering (DDHF) mechanism is adopted to address the uncertain nonlinear drift of the MEMS-RISS and make full use of the supplementary sensors and sources. The DDHF is composed of a main H∞ filter (MHF) and an auxiliary H∞ filter (AHF). Finally, a generalized regression neural network (GRNN) module with good approximation capability is specially designed for the MEMS-RISS. A hybrid methodology which combines the GRNN module and the AHF is utilized to compensate for RISS position errors during GPS outages. To verify the effectiveness of the proposed solution, road-test experiments with various scenarios were performed. The experimental results illustrate that the proposed system can achieve accurate and reliable positioning for land vehicles. PMID:27231917

Method and apparatus for automated, modular, biomass power generation

DOEpatents

Diebold, James P; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael; Smith, Trevor

2013-11-05

Method and apparatus for generating a low tar, renewable fuel gas from biomass and using it in other energy conversion devices, many of which were designed for use with gaseous and liquid fossil fuels. An automated, downdraft gasifier incorporates extensive air injection into the char bed to maintain the conditions that promote the destruction of residual tars. The resulting fuel gas and entrained char and ash are cooled in a special heat exchanger, and then continuously cleaned in a filter prior to usage in standalone as well as networked power systems.

Method and apparatus for automated, modular, biomass power generation

DOEpatents

Diebold, James P [Lakewood, CO; Lilley, Arthur [Finleyville, PA; Browne, Kingsbury III [Golden, CO; Walt, Robb Ray [Aurora, CO; Duncan, Dustin [Littleton, CO; Walker, Michael [Longmont, CO; Steele, John [Aurora, CO; Fields, Michael [Arvada, CO; Smith, Trevor [Lakewood, CO

2011-03-22

Method and apparatus for generating a low tar, renewable fuel gas from biomass and using it in other energy conversion devices, many of which were designed for use with gaseous and liquid fossil fuels. An automated, downdraft gasifier incorporates extensive air injection into the char bed to maintain the conditions that promote the destruction of residual tars. The resulting fuel gas and entrained char and ash are cooled in a special heat exchanger, and then continuously cleaned in a filter prior to usage in standalone as well as networked power systems.

A Multi Directional Perfect Reconstruction Filter Bank Designed with 2-D Eigenfilter Approach: Application to Ultrasound Speckle Reduction.

PubMed

Nagare, Mukund B; Patil, Bhushan D; Holambe, Raghunath S

2017-02-01

B-Mode ultrasound images are degraded by inherent noise called Speckle, which creates a considerable impact on image quality. This noise reduces the accuracy of image analysis and interpretation. Therefore, reduction of speckle noise is an essential task which improves the accuracy of the clinical diagnostics. In this paper, a Multi-directional perfect-reconstruction (PR) filter bank is proposed based on 2-D eigenfilter approach. The proposed method used for the design of two-dimensional (2-D) two-channel linear-phase FIR perfect-reconstruction filter bank. In this method, the fan shaped, diamond shaped and checkerboard shaped filters are designed. The quadratic measure of the error function between the passband and stopband of the filter has been used an objective function. First, the low-pass analysis filter is designed and then the PR condition has been expressed as a set of linear constraints on the corresponding synthesis low-pass filter. Subsequently, the corresponding synthesis filter is designed using the eigenfilter design method with linear constraints. The newly designed 2-D filters are used in translation invariant pyramidal directional filter bank (TIPDFB) for reduction of speckle noise in ultrasound images. The proposed 2-D filters give better symmetry, regularity and frequency selectivity of the filters in comparison to existing design methods. The proposed method is validated on synthetic and real ultrasound data which ensures improvement in the quality of ultrasound images and efficiently suppresses the speckle noise compared to existing methods.

Shaped, lead-loaded acrylic filters for patient exposure reduction and image-quality improvement

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

Gray, J.E.; Stears, J.G.; Frank, E.D.

1983-03-01

Shaped filters that are constructed of lead-loaded acrylic material for use in patient radiography are discussed. Use of the filters will result in improved overall image quality with significant exposure reduction to the patient (approximately a 2X reduction in breast exposure and a 3X reduction in thyroid gland exposure). Detailed drawings of the shaped filters for scoliosis radiography, cervical spine radiography, and for long film changers in special procedures are provided. The use of the scoliosis filters is detailed and includes phantom and patient radiographs and dose reduction information.

Narrow-Band Organic Photodiodes for High-Resolution Imaging.

PubMed

Han, Moon Gyu; Park, Kyung-Bae; Bulliard, Xavier; Lee, Gae Hwang; Yun, Sungyoung; Leem, Dong-Seok; Heo, Chul-Joon; Yagi, Tadao; Sakurai, Rie; Ro, Takkyun; Lim, Seon-Jeong; Sul, Sangchul; Na, Kyoungwon; Ahn, Jungchak; Jin, Yong Wan; Lee, Sangyoon

2016-10-05

There are growing opportunities and demands for image sensors that produce higher-resolution images, even in low-light conditions. Increasing the light input areas through 3D architecture within the same pixel size can be an effective solution to address this issue. Organic photodiodes (OPDs) that possess wavelength selectivity can allow for advancements in this regard. Here, we report on novel push-pull D-π-A dyes specially designed for Gaussian-shaped, narrow-band absorption and the high photoelectric conversion. These p-type organic dyes work both as a color filter and as a source of photocurrents with linear and fast light responses, high sensitivity, and excellent stability, when combined with C60 to form bulk heterojunctions (BHJs). The effectiveness of the OPD composed of the active color filter was demonstrated by obtaining a full-color image using a camera that contained an organic/Si hybrid complementary metal-oxide-semiconductor (CMOS) color image sensor.

Special Reports.

ERIC Educational Resources Information Center

Haycock, Ken; Chapin, Betty; Bruce, David; Durrance, Joan C.; Pettigrew, Karen; Oakley, Robert L.; Juergens, Bonnie; Nevins, Kate

1999-01-01

Presents these special reports: "Information Age Dilemma: Filtering the Internet for Young People"; "KALIPER: A Look at Library and Information Science Education at the Turn of a New Century"; "Copyright 1998: Recalibrating the Balance"; "Library Networking and Cooperation in 1998". (AEF)

Flight prototype regenerative particulate filter system development

NASA Technical Reports Server (NTRS)

Green, D. C.; Garber, P. J.

1974-01-01

The effort to design, fabricate, and test a flight prototype Filter Regeneration Unit used to regenerate (clean) fluid particulate filter elements is reported. The design of the filter regeneration unit and the results of tests performed in both one-gravity and zero-gravity are discussed. The filter regeneration unit uses a backflush/jet impingement method of regenerating fluid filter elements that is highly efficient. A vortex particle separator and particle trap were designed for zero-gravity use, and the zero-gravity test results are discussed. The filter regeneration unit was designed for both inflight maintenance and ground refurbishment use on space shuttle and future space missions.

IIR digital filter design for powerline noise cancellation of ECG signal using arduino platform

NASA Astrophysics Data System (ADS)

Rahmatillah, Akif; Ataulkarim

2017-05-01

Powerline noise has been one of significant noises of Electrocardiogram (ECG) signal measurement. This noise is characterized by a sinusoidal signal which has 50 Hz of noise and 0.3 mV of maximum amplitude. This paper describes the design of IIR Notch filter design to reject a 50 Hz power line noise. IIR filter coefficients were calculated using pole placement method with three variations of band stop cut off frequencies of (49-51)Hz, (48 - 52)Hz, and (47 - 53)Hz. The algorithm and coefficients of filter were embedded to Arduino DUE (ARM 32 bit microcontroller). IIR notch filter designed has been able to reject power line noise with average square of error value of 0.225 on (49-51) Hz filter design and 0.2831 on (48 - 52)Hz filter design.

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection.

PubMed

Kontson, Kimberly; Jennings, Robert J

2015-09-01

For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the penelope Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using penelope and reconstructed using FBP. Parameters such as dose distribution, noise uniformity, and scatter were investigated. Analytical calculations with and without each bowtie filter show that some materials for a given design produce bowtie filters that are too large for implementation in breast CT scanners or too small to accurately manufacture. Results also demonstrate the ability to manipulate the energy fluence distribution (dynamic range) by using different materials, or different combinations of materials, for a given bowtie filter design. This feature is especially advantageous when using photon counting detector technology. Monte Carlo simulation results from penelope show that all studied material choices for bowtie design #2 achieve nearly uniform dose distribution, noise uniformity index less than 5%, and nearly uniform scatter-to-primary ratio. These same features can also be obtained using certain materials with bowtie designs #1 and #3. With the three bowtie filter designs used in this work, the selection of material is an important design consideration. An appropriate material choice can improve image quality, dose uniformity, and dynamic range.

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.

Are too many inferior vena cava filters used? Controversial evidences in different clinical settings: a narrative review.

PubMed

Dalla Vestra, Michele; Grolla, Elisabetta; Bonanni, Luca; Pesavento, Raffaele

2018-03-01

The use of inferior vena cava filters to prevent pulmonary embolism is increasing mainly because of indications that appear to be unclearly codified and recommended. The evidence supporting this approach is often heterogeneous, and mainly based on observational studies and consensus opinions, while the insertion of an IVC filter exposes patients to the risk of complications and increases health care costs. Thus, several proposed indications for an IVC filter placement remain controversial. We attempt to review the proof on the efficacy and safety of IVC filters in several "special" clinical settings, and assess the robustness of the available evidence for any specific indication to place an IVC filter.

Bowtie filters for dedicated breast CT: Theory and computational implementation

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

Kontson, Kimberly, E-mail: Kimberly.Kontson@fda.hhs.gov; Jennings, Robert J.

Purpose: To design bowtie filters with improved properties for dedicated breast CT to improve image quality and reduce dose to the patient. Methods: The authors present three different bowtie filters designed for a cylindrical 14-cm diameter phantom with a uniform composition of 40/60 breast tissue, which vary in their design objectives and performance improvements. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis material decomposition to produce the same spectral shape and intensity at the detector, using two differentmore » materials. Bowtie design #3 eliminates the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. All three designs are obtained using analytical computational methods and linear attenuation coefficients. Thus, the designs do not take into account the effects of scatter. The authors considered this to be a reasonable approach to the filter design problem since the use of Monte Carlo methods would have been computationally intensive. The filter profiles for a cone-angle of 0° were used for the entire length of each filter because the differences between those profiles and the correct cone-beam profiles for the cone angles in our system are very small, and the constant profiles allowed construction of the filters with the facilities available to us. For evaluation of the filters, we used Monte Carlo simulation techniques and the full cone-beam geometry. Images were generated with and without each bowtie filter to analyze the effect on dose distribution, noise uniformity, and contrast-to-noise ratio (CNR) homogeneity. Line profiles through the reconstructed images generated from the simulated projection images were also used as validation for the filter designs. Results: Examples of the three designs are presented. Initial verification of performance of the designs was done using analytical computations of HVL, intensity, and effective attenuation coefficient behind the phantom as a function of fan-angle with a cone-angle of 0°. The performance of the designs depends only weakly on incident spectrum and tissue composition. For all designs, the dynamic range requirement on the detector was reduced compared to the no-bowtie-filter case. Further verification of the filter designs was achieved through analysis of reconstructed images from simulations. Simulation data also showed that the use of our bowtie filters can reduce peripheral dose to the breast by 61% and provide uniform noise and CNR distributions. The bowtie filter design concepts validated in this work were then used to create a computational realization of a 3D anthropomorphic bowtie filter capable of achieving a constant effective attenuation coefficient behind the entire field-of-view of an anthropomorphic breast phantom. Conclusions: Three different bowtie filter designs that vary in performance improvements were described and evaluated using computational and simulation techniques. Results indicate that the designs are robust against variations in breast diameter, breast composition, and tube voltage, and that the use of these filters can reduce patient dose and improve image quality compared to the no-bowtie-filter case.« less

Indigenous technology development and standardization of the process for obtaining ready to use sterile sodium pertechnetate-Tc-99m solution from Geltech generator

PubMed Central

Sarkar, Sishir Kumar; Kothalkar, Chetan; Naskar, Prabhakar; Joshi, Sangeeta; Saraswathy, Padmanabhan; Dey, Arun Chandra; Vispute, Gunvant Leeladhar; Murhekar, Vishwas Vinayak; Pilkhwal, Neelam

2013-01-01

Purpose of the Study: The indigenous design and technology development for processing large scale zirconium molybdate-Mo-99 (ZrMo-99) Geltech generator was successfully commissioned in Board of Radiation and Isotope Technology (BRIT), India, in 2006. The generator production facility comprises of four shielded plant facilities equipped with tongs and special process gadgets amenable for remote operations for radiochemical processing of ZrMo-99 gel. Results: Over 2800 Geltech generators have been processed and supplied to user hospitals during the period 2006-2013. Geltech generator supplied by BRIT was initially not sterile. Simple elution of Tc-99m is performed by a sterile evacuated vial with sterile and pyrogen free 0.9% NaCl solution to obtain sodium (Tc-99m) pertechnetate solution. A special type online 0.22 μm membrane filter has been identified and adapted in Geltech generator. Conclusions: The online filtration of Tc-99m from Geltech generator; thus, provided sterile Tc-99m sodium pertechnetate solution. Generators assembled with modified filter assembly were supplied to local hospital in Mumbai Radiation Medicine Centre (RMC) and S.G.S. Medical College and KEM Hospital) and excellent performances were reported by users. PMID:24163509

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

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

Kontson, Kimberly, E-mail: Kimberly.Kontson@fda.hhs.gov; Jennings, Robert J.

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designsmore » were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity, and scatter were investigated. Results: Analytical calculations with and without each bowtie filter show that some materials for a given design produce bowtie filters that are too large for implementation in breast CT scanners or too small to accurately manufacture. Results also demonstrate the ability to manipulate the energy fluence distribution (dynamic range) by using different materials, or different combinations of materials, for a given bowtie filter design. This feature is especially advantageous when using photon counting detector technology. Monte Carlo simulation results from PENELOPE show that all studied material choices for bowtie design #2 achieve nearly uniform dose distribution, noise uniformity index less than 5%, and nearly uniform scatter-to-primary ratio. These same features can also be obtained using certain materials with bowtie designs #1 and #3. Conclusions: With the three bowtie filter designs used in this work, the selection of material is an important design consideration. An appropriate material choice can improve image quality, dose uniformity, and dynamic range.« less

Reflective Filters Design for Self-Filtering Narrowband Ultraviolet Imaging Experiment Wide-Field Surveys (NUVIEWS) Project

NASA Technical Reports Server (NTRS)

Park, Jung- Ho; Kim, Jongmin; Zukic, Muamer; Torr, Douglas G.

1994-01-01

We report the design of multilayer reflective filters for the self-filtering cameras of the NUVIEWS project. Wide angle self-filtering cameras were designed to image the C IV (154.9 nm) line emission, and H2 Lyman band fluorescence (centered at 161 nm) over a 20 deg x 30 deg field of view. A key element of the filter design includes the development of pi-multilayers optimized to provide maximum reflectance at 154.9 nm and 161 nm for the respective cameras without significant spectral sensitivity to the large cone angle of the incident radiation. We applied self-filtering concepts to design NUVIEWS telescope filters that are composed of three reflective mirrors and one folding mirror. The filters with narrowband widths of 6 and 8 rim at 154.9 and 161 nm, respectively, have net throughputs of more than 50 % with average blocking of out-of-band wavelengths better than 3 x 10(exp -4)%.

Distributed meandering waveguides (DMWs) for novel photonic circuits (Conference Presentation)

NASA Astrophysics Data System (ADS)

Dag, Ceren B.; Anil, Mehmet Ali; Serpengüzel, Ali

2017-05-01

Meandering waveguide distributed feedback structures are novel integrated photonic lightwave and microwave circuit elements. Meandering waveguide distributed feedback structures with a variety of spectral responses can be designed for a variety of lightwave and microwave circuit element functions. Distributed meandering waveguide (DMW) structures [1] show a variety of spectral behaviors with respect to the number of meandering loop mirrors (MLMs) [2] used in their composition as well as their internal coupling constants (Cs). DMW spectral behaviors include Fano resonances, coupled resonator induced transparency (CRIT), notch, add-drop, comb, and hitless filters. What makes the DMW special is the self-coupling property intrinsic to the DMW's nature. The basic example of DMW's nature is motivated through the analogy between the so-called symmetric meandering resonator (SMR), which consists of two coupled MLMs, and the resonator enhanced Mach-Zehnder interferometer (REMZI) [3]. A SMR shows the same spectral characteristics of Fano resonances with its self-coupling property, similar to the single, distributed and binary self coupled optical waveguide (SCOW) resonators [4]. So far DMWs have been studied for their electric field intensity, phase [5] and phasor responses [6]. The spectral analysis is performed using the coupled electric field analysis and the generalization of single meandering loop mirrors to multiple meandering distributed feedback structures is performed with the transfer matrix method. The building block of the meandering waveguide structures, the meandering loop mirror (MLM), is the integrated analogue of the fiber optic loop mirrors. The meandering resonator (MR) is composed of two uncoupled MLM's. The meandering distributed feedback (MDFB) structure is the DFB of the MLM. The symmetric MR (SMR) is composed of two coupled MLM's, and has the characteristics of a Fano resonator in the general case, and tunable power divider or tunable hitless filter in special cases. The antisymmetric MR (AMR) is composed of two coupled MLM's. The AMR has the characteristics of an add-drop filter in the general case, and coupled resonator induced transparency (CRIT) filter in a special case. The symmetric MDFB (SMDFB) is composed of multiple coupled MLM's. The antisymmetric MDFB (AMDFB) is composed of multiple coupled MLM's. The SMDFB and AMDFB can be utilized as band-pass, Fano, or Lorentzian filters, or Rabi splitters. Distributed meandering waveguide elements with extremely rich spectral and phase responses can be designed with creative combinations of distributed meandering waveguides structures for various novel photonic circuits. References [1 ] C. B. Dağ, M. A. Anıl, and A. Serpengüzel, "Meandering Waveguide Distributed Feedback Lightwave Circuits," J. Lightwave Technol, vol. 33, no. 9, pp. 1691-1702, May 2015. [2] N. J. Doran and D. Wood, "Nonlinear-optical loop mirror," Opt. Lett. vol. 13, no. 1, pp. 56-58, Jan. 1988. [3] L. Zhou and A. W. Poon, "Fano resonance-based electrically reconfigurable add-drop filters in silicon microring resonator-coupled Mach-Zehnder interferometers," Opt. Lett. vol. 32, no. 7, pp. 781-783, Apr. 2007. [4] Z. Zou, L. Zhou, X. Sun, J. Xie, H. Zhu, L. Lu, X. Li, and J. Chen, "Tunable two-stage self-coupled optical waveguide resonators," Opt. Lett. vol. 38, no. 8, pp. 1215-1217, Apr. 2013. [5] C. B. Dağ, M. A. Anıl, and A. Serpengüzel, "Novel distributed feedback lightwave circuit elements," in Proc. SPIE, San Francisco, 2015, vol. 9366, p. 93660A. [6] C. B. Dağ, M. A. Anıl, and A. Serpengüzel, "Meandering Waveguide Distributed Feedback Lightwave Elements: Phasor Diagram Analysis," in Proc. PIERS, Prague, 1986-1990 (2015).

Ultra-compact imaging plate scanner module using a MEMS mirror and specially designed MPPC

NASA Astrophysics Data System (ADS)

Miyamoto, Yuichi; Sasaki, Kensuke; Takasaka, Masaomi; Fujimoto, Masatoshi; Yamamoto, Koei

2017-02-01

Computed radiography (CR), which is one of the most useful methods for dental imaging and nondestructive testing, uses a phosphor imaging plate (IP) because it is flexible, reusable, and inexpensive. Conventional IP scanners utilize a galvanometer or a polygon mirror as a scanning device and a photomultiplier as an optical sensor. Microelectromechanical systems (MEMS) technology currently provides silicon-based devices and has the potential to replace such discrete devices and sensors. Using these devices, we constructed an ultra-compact IP scanner. Our extremely compact plate scanner utilizes a module that is composed of a one-dimensional MEMS mirror and a long multi-pixel photon counter (MPPC) that is combined with a specially designed wavelength filter and a rod lens. The MEMS mirror, which is a non-resonant electromagnetic type, is 2.6 mm in diameter with a recommended optical scanning angle up to +/-15°. The CR's wide dynamic range is maintained using a newly developed MPPC. The MPPC is a sort of silicon photomultiplier and is a high-sensitivity photon-counting device. To achieve such a wide dynamic range, we developed a long MPPC that has over 10,000 pixels. For size reduction and high optical efficiency, we set the MPPC close to an IP across the rod lens. To prevent the MPPC from detecting excitation light, which is much more intense than photo-stimulated light, we produced a sharp-cut wavelength filter that has a wide angle (+/-60°) of tolerance. We evaluated our constructed scanner module through gray chart and resolution chart images.

Real-valued composite filters for correlation-based optical pattern recognition

NASA Technical Reports Server (NTRS)

Rajan, P. K.; Balendra, Anushia

1992-01-01

Advances in the technology of optical devices such as spatial light modulators (SLMs) have influenced the research and growth of optical pattern recognition. In the research leading to this report, the design of real-valued composite filters that can be implemented using currently available SLMs for optical pattern recognition and classification was investigated. The design of real-valued minimum average correlation energy (RMACE) filter was investigated. Proper selection of the phase of the output response was shown to reduce the correlation energy. The performance of the filter was evaluated using computer simulations and compared with the complex filters. It was found that the performance degraded only slightly. Continuing the above investigation, the design of a real filter that minimizes the output correlation energy and the output variance due to noise was developed. Simulation studies showed that this filter had better tolerance to distortion and noise compared to that of the RMACE filter. Finally, the space domain design of RMACE filter was developed and implemented on the computer. It was found that the sharpness of the correlation peak was slightly reduced but the filter design was more computationally efficient than the complex filter.

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 rejection, and constant bandwidth is designed, simulated, fabricated and measured. The filters are fabricated using barium strontium titanate (BST) varactors. Electromagnetic simulations and measured results of the tunable two-pole ferroelectric filter are analyzed to explore the origins of high insertion loss in ferroelectric filters. The results indicate that the high-permittivity of the BST (a ferroelectric) not only makes the filters tunable and compact, but also increases the conductive loss of the ferroelectric-based tunable resonators which translates into high insertion loss in ferroelectric filters.

Design of an S band narrow-band bandpass BAW filter

NASA Astrophysics Data System (ADS)

Gao, Yang; Zhao, Kun-li; Han, Chao

2017-11-01

An S band narrowband bandpass filter BAW with center frequency 2.460 GHz, bandwidth 41MHz, band insertion loss - 1.154 dB, the passband ripple 0.9 dB, the out of band rejection about -42.5dB@2.385 GHz; -45.5dB@2.506 GHz was designed for potential UAV measurement and control applications. According to the design specifications, the design is as follows: each FBAR's stack was designed in BAW filter by using Mason model. Each FBAR's shape was designed with the method of apodization electrode. The layout of BAW filter was designed. The acoustic-electromagnetic cosimulation model was built to validate the performance of the designed BAW filter. The presented design procedure is a common one, and there are two characteristics: 1) an A and EM co-simulation method is used for the final BAW filter performance validation in the design stage, thus ensures over-optimistic designs by the bare 1D Mason model are found and rejected in time; 2) An in-house developed auto-layout method is used to get compact BAW filter layout, which simplifies iterative error-and-try work here and output necessary in-plane geometry information to the A and EM cosimulation model.

Design of miniature type parallel coupled microstrip hairpin filter in UHF range

NASA Astrophysics Data System (ADS)

Hasan, Adib Belhaj; Rahman, Maj Tarikur; Kahhar, Azizul; Trina, Tasnim; Saha, Pran Kanai

2017-12-01

A microstrip parallel coupled line bandpass filter is designed in UHF range and the filter size is reduced by microstrip hairpin structure. The FR4 substrate is used as base material of the filter. The filter is analyzed by both ADS and CST design studio in the frequency range of 500 MHz to 650 MHz. The Bandwidth is found 13.27% with a center frequency 570 MHz. Simulation from both ADS and CST shows a very good agreement of performance of the filter.

Restoration of Static JPEG Images and RGB Video Frames by Means of Nonlinear Filtering in Conditions of Gaussian and Non-Gaussian Noise

NASA Astrophysics Data System (ADS)

Sokolov, R. I.; Abdullin, R. R.

2017-11-01

The use of nonlinear Markov process filtering makes it possible to restore both video stream frames and static photos at the stage of preprocessing. The present paper reflects the results of research in comparison of these types image filtering quality by means of special algorithm when Gaussian or non-Gaussian noises acting. Examples of filter operation at different values of signal-to-noise ratio are presented. A comparative analysis has been performed, and the best filtered kind of noise has been defined. It has been shown the quality of developed algorithm is much better than quality of adaptive one for RGB signal filtering at the same a priori information about the signal. Also, an advantage over median filter takes a place when both fluctuation and pulse noise filtering.

The intractable cigarette 'filter problem'.

PubMed

Harris, Bradford

2011-05-01

When lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the industry identified as the 'filter problem'. These extensive filter research and development efforts suggest a phase of genuine optimism among cigarette designers that cigarette filters could be engineered to mitigate the health hazards of smoking. This paper explores the early history of cigarette filter research and development in order to elucidate why and when seemingly sincere filter engineering efforts devolved into manipulations in cigarette design to sustain cigarette marketing and mitigate consumers' concerns about the health consequences of smoking. Relevant word and phrase searches were conducted in the Legacy Tobacco Documents Library online database, Google Patents, and media and medical databases including ProQuest, JSTOR, Medline and PubMed. 13 tobacco industry documents were identified that track prominent developments involved in what the industry referred to as the 'filter problem'. These reveal a period of intense focus on the 'filter problem' that persisted from the mid-1950s to the mid-1960s, featuring collaborations between cigarette producers and large American chemical and textile companies to develop effective filters. In addition, the documents reveal how cigarette filter researchers' growing scientific knowledge of smoke chemistry led to increasing recognition that filters were unlikely to offer significant health protection. One of the primary concerns of cigarette producers was to design cigarette filters that could be economically incorporated into the massive scale of cigarette production. The synthetic plastic cellulose acetate became the fundamental cigarette filter material. By the mid-1960s, the meaning of the phrase 'filter problem' changed, such that the effort to develop effective filters became a campaign to market cigarette designs that would sustain the myth of cigarette filter efficacy. This study indicates that cigarette designers at Philip Morris, British-American Tobacco, Lorillard and other companies believed for a time that they might be able to reduce some of the most dangerous substances in mainstream smoke through advanced engineering of filter tips. In their attempts to accomplish this, they developed the now ubiquitous cellulose acetate cigarette filter. By the mid-1960s cigarette designers realised that the intractability of the 'filter problem' derived from a simple fact: that which is harmful in mainstream smoke and that which provides the smoker with 'satisfaction' are essentially one and the same. Only in the wake of this realisation did the agenda of cigarette designers appear to transition away from mitigating the health hazards of smoking and towards the perpetuation of the notion that cigarette filters are effective in reducing these hazards. Filters became a marketing tool, designed to keep and recruit smokers as consumers of these hazardous products.

Application of reversible denoising and lifting steps with step skipping to color space transforms for improved lossless compression

NASA Astrophysics Data System (ADS)

Starosolski, Roman

2016-07-01

Reversible denoising and lifting steps (RDLS) are lifting steps integrated with denoising filters in such a way that, despite the inherently irreversible nature of denoising, they are perfectly reversible. We investigated the application of RDLS to reversible color space transforms: RCT, YCoCg-R, RDgDb, and LDgEb. In order to improve RDLS effects, we propose a heuristic for image-adaptive denoising filter selection, a fast estimator of the compressed image bitrate, and a special filter that may result in skipping of the steps. We analyzed the properties of the presented methods, paying special attention to their usefulness from a practical standpoint. For a diverse image test-set and lossless JPEG-LS, JPEG 2000, and JPEG XR algorithms, RDLS improves the bitrates of all the examined transforms. The most interesting results were obtained for an estimation-based heuristic filter selection out of a set of seven filters; the cost of this variant was similar to or lower than the transform cost, and it improved the average lossless JPEG 2000 bitrates by 2.65% for RDgDb and by over 1% for other transforms; bitrates of certain images were improved to a significantly greater extent.

New Capabilities of One-Meter Schmidt Telescope of the Byurakan Astrophysical Observatory after modernization

NASA Astrophysics Data System (ADS)

Movsessian, T. A.; Dodonov, S. N.; Gabrielyan, V. V.; Kotov, S. S.; Gevorgyan, M. H.

2017-12-01

Within the framework of cooperation between Byurakan Astrophysical Observatory and Special Astrophysical Observatory during 2013-2015 y the 1-m Schmidt telescope of the Byurakan Astrophysical was upgraded. We completely redesigned the control system of the telescope: we replaced the actuating mechanisms, developed telescope control software, and made the guiding system. In the Special Astrophysical Observatory, the 4k×4k Apogee (USA) liquid-cooled CCD was reworked and prepared. Detector was mounted in the focus of the telescope and provides 1-degree field of view with pixel-size of 0.868, and RON 11e-. The detector is equipped with a turret with 5 holes for filters. The 20 intermediate-band filters (FWHM= 250A) uniformly covering the 4000&-9000Å wavelength range, five broadband filters (u, g, r, i, z SDSS), and three narrow-band filters. During the first year of test operation of the 1-m telescope we performed pilot observations within the framework of three programs: search for young stellar objects, AGN evolution, and stellar composition of galaxy disks. We confirmed the possibility of efficiently selecting of young objects using observations performed in narrow-band Hα and [S II] filters and the intermediate-band 7500Å filter. Three-hours long exposures with SDSS g, r, and i band filters allow us to reach the surface brightness level of 28m from square arcsecond when investigating the stellar content of galaxy disks for a sample of nine galaxies. We used observations performed with the 1-m telescope in five broadband (SDSS u, g, r, i, and z) and 15 intermediate-band filters (4000-7500Å) to construct a sample of quasar candidates with 0.5

Miniaturized dielectric waveguide filters

NASA Astrophysics Data System (ADS)

Sandhu, Muhammad Y.; Hunter, Ian C.

2016-10-01

Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.

Design Techniques for Uniform-DFT, Linear Phase Filter Banks

NASA Technical Reports Server (NTRS)

Sun, Honglin; DeLeon, Phillip

1999-01-01

Uniform-DFT filter banks are an important class of filter banks and their theory is well known. One notable characteristic is their very efficient implementation when using polyphase filters and the FFT. Separately, linear phase filter banks, i.e. filter banks in which the analysis filters have a linear phase are also an important class of filter banks and desired in many applications. Unfortunately, it has been proved that one cannot design critically-sampled, uniform-DFT, linear phase filter banks and achieve perfect reconstruction. In this paper, we present a least-squares solution to this problem and in addition prove that oversampled, uniform-DFT, linear phase filter banks (which are also useful in many applications) can be constructed for perfect reconstruction. Design examples are included illustrate the methods.

Design of multiplier-less sharp transition width non-uniform filter banks using gravitational search algorithm

NASA Astrophysics Data System (ADS)

Bindiya T., S.; Elias, Elizabeth

2015-01-01

In this paper, multiplier-less near-perfect reconstruction tree-structured filter banks are proposed. Filters with sharp transition width are preferred in filter banks in order to reduce the aliasing between adjacent channels. When sharp transition width filters are designed as conventional finite impulse response filters, the order of the filters will become very high leading to increased complexity. The frequency response masking (FRM) method is known to result in linear-phase sharp transition width filters with low complexity. It is found that the proposed design method, which is based on FRM, gives better results compared to the earlier reported results, in terms of the number of multipliers when sharp transition width filter banks are needed. To further reduce the complexity and power consumption, the tree-structured filter bank is made totally multiplier-less by converting the continuous filter bank coefficients to finite precision coefficients in the signed power of two space. This may lead to performance degradation and calls for the use of a suitable optimisation technique. In this paper, gravitational search algorithm is proposed to be used in the design of the multiplier-less tree-structured uniform as well as non-uniform filter banks. This design method results in uniform and non-uniform filter banks which are simple, alias-free, linear phase and multiplier-less and have sharp transition width.

Design of coupled mace filters for optical pattern recognition using practical spatial light modulators

NASA Technical Reports Server (NTRS)

Rajan, P. K.; Khan, Ajmal

1993-01-01

Spatial light modulators (SLMs) are being used in correlation-based optical pattern recognition systems to implement the Fourier domain filters. Currently available SLMs have certain limitations with respect to the realizability of these filters. Therefore, it is necessary to incorporate the SLM constraints in the design of the filters. The design of a SLM-constrained minimum average correlation energy (SLM-MACE) filter using the simulated annealing-based optimization technique was investigated. The SLM-MACE filter was synthesized for three different types of constraints. The performance of the filter was evaluated in terms of its recognition (discrimination) capabilities using computer simulations. The correlation plane characteristics of the SLM-MACE filter were found to be reasonably good. The SLM-MACE filter yielded far better results than the analytical MACE filter implemented on practical SLMs using the constrained magnitude technique. Further, the filter performance was evaluated in the presence of noise in the input test images. This work demonstrated the need to include the SLM constraints in the filter design. Finally, a method is suggested to reduce the computation time required for the synthesis of the SLM-MACE filter.

Control design for robust stability in linear regulators: Application to aerospace flight control

NASA Technical Reports Server (NTRS)

Yedavalli, R. K.

1986-01-01

Time domain stability robustness analysis and design for linear multivariable uncertain systems with bounded uncertainties is the central theme of the research. After reviewing the recently developed upper bounds on the linear elemental (structured), time varying perturbation of an asymptotically stable linear time invariant regulator, it is shown that it is possible to further improve these bounds by employing state transformations. Then introducing a quantitative measure called the stability robustness index, a state feedback conrol design algorithm is presented for a general linear regulator problem and then specialized to the case of modal systems as well as matched systems. The extension of the algorithm to stochastic systems with Kalman filter as the state estimator is presented. Finally an algorithm for robust dynamic compensator design is presented using Parameter Optimization (PO) procedure. Applications in a aircraft control and flexible structure control are presented along with a comparison with other existing methods.

Identification and characterization of functional aquaporin water channel protein from alimentary tract of whitefly, Bemisia tabaci

USDA-ARS?s Scientific Manuscript database

Some hemipteran xylem and phloem feeding insects have evolved specialized alimentary structures or filter chambers that rapidly transport water for excretion or osmoregulation. In the whitefly, Bemisia tabaci, mass movement of water through opposing alimentary tract tissues within the filter chamber...

A comparison of methods for DPLL loop filter design

NASA Technical Reports Server (NTRS)

Aguirre, S.; Hurd, W. J.; Kumar, R.; Statman, J.

1986-01-01

Four design methodologies for loop filters for a class of digital phase-locked loops (DPLLs) are presented. The first design maps an optimum analog filter into the digital domain; the second approach designs a filter that minimizes in discrete time weighted combination of the variance of the phase error due to noise and the sum square of the deterministic phase error component; the third method uses Kalman filter estimation theory to design a filter composed of a least squares fading memory estimator and a predictor. The last design relies on classical theory, including rules for the design of compensators. Linear analysis is used throughout the article to compare different designs, and includes stability, steady state performance and transient behavior of the loops. Design methodology is not critical when the loop update rate can be made high relative to loop bandwidth, as the performance approaches that of continuous time. For low update rates, however, the miminization method is significantly superior to the other methods.

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.

40 CFR 430.121 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Specialized definitions. 430.121 Section 430.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Tissue, Filter, Non...

40 CFR 430.121 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Specialized definitions. 430.121 Section 430.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Tissue, Filter, Non-Woven, and...

40 CFR 430.121 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Specialized definitions. 430.121 Section 430.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Tissue, Filter, Non...

40 CFR 430.121 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Specialized definitions. 430.121 Section 430.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Tissue, Filter, Non...

40 CFR 430.121 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Specialized definitions. 430.121 Section 430.121 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Tissue, Filter, Non-Woven, and...

Initial Ares I Bending Filter Design

NASA Technical Reports Server (NTRS)

Jang, Jiann-Woei; Bedrossian, Nazareth; Hall, Robert; Norris, H. Lee; Hall, Charles; Jackson, Mark

2007-01-01

The Ares-I launch vehicle represents a challenging flex-body structural environment for control system design. Software filtering of the inertial sensor output will be required to ensure control system stability and adequate performance. This paper presents a design methodology employing numerical optimization to develop the Ares-I bending filters. The filter design methodology was based on a numerical constrained optimization approach to maximize stability margins while meeting performance requirements. The resulting bending filter designs achieved stability by adding lag to the first structural frequency and hence phase stabilizing the first Ares-I flex mode. To minimize rigid body performance impacts, a priority was placed via constraints in the optimization algorithm to minimize bandwidth decrease with the addition of the bending filters. The bending filters provided here have been demonstrated to provide a stable first stage control system in both the frequency domain and the MSFC MAVERIC time domain simulation.

Interferometric interrogation of π-phase shifted fiber Bragg grating sensors

NASA Astrophysics Data System (ADS)

Srivastava, Deepa; Tiwari, Umesh; Das, Bhargab

2018-03-01

Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrates that high resolution weak dynamic strain measurement down to 4 pε /√{ Hz } is easily achievable. Preliminary experimental results are also presented as proof-of-concept of the proposed interrogation principle.

The filter and calibration wheel for the ATHENA wide field imager

NASA Astrophysics Data System (ADS)

Rataj, M.; Polak, S.; Palgan, T.; Kamisiński, T.; Pilch, A.; Eder, J.; Meidinger, N.; Plattner, M.; Barbera, M.; Parodi, G.; D'Anca, Fabio

2016-07-01

The planned filter and calibration wheel for the Wide Field Imager (WFI) instrument on Athena is presented. With four selectable positions it provides the necessary functions, in particular an UV/VIS blocking filter for the WFI detectors and a calibration source. Challenges for the filter wheel design are the large volume and mass of the subsystem, the implementation of a robust mechanism and the protection of the ultra-thin filter with an area of 160 mm square. This paper describes performed trade-offs based on simulation results and describes the baseline design in detail. Reliable solutions are envisaged for the conceptual design of the filter and calibration wheel. Four different variant with different position of the filter are presented. Risk mitigation and the compliance to design requirements are demonstrated.

Input filter compensation for switching regulators

NASA Technical Reports Server (NTRS)

Lee, F. C.; Kelkar, S. S.

1982-01-01

The problems caused by the interaction between the input filter, output filter, and the control loop are discussed. The input filter design is made more complicated because of the need to avoid performance degradation and also stay within the weight and loss limitations. Conventional input filter design techniques are then dicussed. The concept of pole zero cancellation is reviewed; this concept is the basis for an approach to control the peaking of the output impedance of the input filter and thus mitigate some of the problems caused by the input filter. The proposed approach for control of the peaking of the output impedance of the input filter is to use a feedforward loop working in conjunction with feedback loops, thus forming a total state control scheme. The design of the feedforward loop for a buck regulator is described. A possible implementation of the feedforward loop design is suggested.

The intractable cigarette ‘filter problem’

PubMed Central

2011-01-01

Background When lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the industry identified as the ‘filter problem’. These extensive filter research and development efforts suggest a phase of genuine optimism among cigarette designers that cigarette filters could be engineered to mitigate the health hazards of smoking. Objective This paper explores the early history of cigarette filter research and development in order to elucidate why and when seemingly sincere filter engineering efforts devolved into manipulations in cigarette design to sustain cigarette marketing and mitigate consumers' concerns about the health consequences of smoking. Methods Relevant word and phrase searches were conducted in the Legacy Tobacco Documents Library online database, Google Patents, and media and medical databases including ProQuest, JSTOR, Medline and PubMed. Results 13 tobacco industry documents were identified that track prominent developments involved in what the industry referred to as the ‘filter problem’. These reveal a period of intense focus on the ‘filter problem’ that persisted from the mid-1950s to the mid-1960s, featuring collaborations between cigarette producers and large American chemical and textile companies to develop effective filters. In addition, the documents reveal how cigarette filter researchers' growing scientific knowledge of smoke chemistry led to increasing recognition that filters were unlikely to offer significant health protection. One of the primary concerns of cigarette producers was to design cigarette filters that could be economically incorporated into the massive scale of cigarette production. The synthetic plastic cellulose acetate became the fundamental cigarette filter material. By the mid-1960s, the meaning of the phrase ‘filter problem’ changed, such that the effort to develop effective filters became a campaign to market cigarette designs that would sustain the myth of cigarette filter efficacy. Conclusions This study indicates that cigarette designers at Philip Morris, British-American Tobacco, Lorillard and other companies believed for a time that they might be able to reduce some of the most dangerous substances in mainstream smoke through advanced engineering of filter tips. In their attempts to accomplish this, they developed the now ubiquitous cellulose acetate cigarette filter. By the mid-1960s cigarette designers realised that the intractability of the ‘filter problem’ derived from a simple fact: that which is harmful in mainstream smoke and that which provides the smoker with ‘satisfaction’ are essentially one and the same. Only in the wake of this realisation did the agenda of cigarette designers appear to transition away from mitigating the health hazards of smoking and towards the perpetuation of the notion that cigarette filters are effective in reducing these hazards. Filters became a marketing tool, designed to keep and recruit smokers as consumers of these hazardous products. PMID:21504917

Non-uniform cosine modulated filter banks using meta-heuristic algorithms in CSD space.

PubMed

Kalathil, Shaeen; Elias, Elizabeth

2015-11-01

This paper presents an efficient design of non-uniform cosine modulated filter banks (CMFB) using canonic signed digit (CSD) coefficients. CMFB has got an easy and efficient design approach. Non-uniform decomposition can be easily obtained by merging the appropriate filters of a uniform filter bank. Only the prototype filter needs to be designed and optimized. In this paper, the prototype filter is designed using window method, weighted Chebyshev approximation and weighted constrained least square approximation. The coefficients are quantized into CSD, using a look-up-table. The finite precision CSD rounding, deteriorates the filter bank performances. The performances of the filter bank are improved using suitably modified meta-heuristic algorithms. The different meta-heuristic algorithms which are modified and used in this paper are Artificial Bee Colony algorithm, Gravitational Search algorithm, Harmony Search algorithm and Genetic algorithm and they result in filter banks with less implementation complexity, power consumption and area requirements when compared with those of the conventional continuous coefficient non-uniform CMFB.

Non-uniform cosine modulated filter banks using meta-heuristic algorithms in CSD space

PubMed Central

Kalathil, Shaeen; Elias, Elizabeth

2014-01-01

This paper presents an efficient design of non-uniform cosine modulated filter banks (CMFB) using canonic signed digit (CSD) coefficients. CMFB has got an easy and efficient design approach. Non-uniform decomposition can be easily obtained by merging the appropriate filters of a uniform filter bank. Only the prototype filter needs to be designed and optimized. In this paper, the prototype filter is designed using window method, weighted Chebyshev approximation and weighted constrained least square approximation. The coefficients are quantized into CSD, using a look-up-table. The finite precision CSD rounding, deteriorates the filter bank performances. The performances of the filter bank are improved using suitably modified meta-heuristic algorithms. The different meta-heuristic algorithms which are modified and used in this paper are Artificial Bee Colony algorithm, Gravitational Search algorithm, Harmony Search algorithm and Genetic algorithm and they result in filter banks with less implementation complexity, power consumption and area requirements when compared with those of the conventional continuous coefficient non-uniform CMFB. PMID:26644921

Wet particle source identification and reduction using a new filter cleaning process

NASA Astrophysics Data System (ADS)

Umeda, Toru; Morita, Akihiko; Shimizu, Hideki; Tsuzuki, Shuichi

2014-03-01

Wet particle reduction during filter installation and start-up aligns closely with initiatives to reduce both chemical consumption and preventative maintenance time. The present study focuses on the effects of filter materials cleanliness on wet particle defectivity through evaluation of filters that have been treated with a new enhanced cleaning process focused on organic compounds reduction. Little difference in filter performance is observed between the two filter types at a size detection threshold of 60 nm, while clear differences are observed at that of 26 nm. It can be suggested that organic compounds can be identified as a potential source of wet particles. Pall recommends filters that have been treated with the special cleaning process for applications with a critical defect size of less than 60 nm. Standard filter products are capable to satisfy wet particle defect performance criteria in less critical lithography applications.

Chromotherapy of macular degeneration with transitions lenses and green-yellow medical filters and special programme for psychoorganic disturbances.

PubMed

Vojniković, Bozo; Vojniković, Davor

2010-04-01

Optical spectrum of the sunlight consists of visible or chromatic spectrum, with the range of wavelengths of electromagnetic vibrations from 7700 to 3900 AU, and the invisible spectrum: infrared and ultraviolet. Chromatic spectrum gives rise to the sensation of colour, capable for simulating specialized retinal photoreceptors and is perceptible as light. This rule of perception of the particular range of the optical spectrum goes mainly for man, while particular deviations, more or less, are applicable to the rest of animal and plant life. The optical part of the spectrum belongs to nonionizing radiation. It created the life on the Earth, maintaining it nowadays and even threatening the human organ of vision, because the retina had not been yet adequately accommodated through evolution with its photoreactive metabolism. Human retina is very sensitive about possible harmful influence of ultraviolet and blue light even today in evolution, but also phototoxic on complete strong visible light. In their clinical and experimental work on animals, the authors prove with their own patent (P 20020077A)-Vojniković B&D, and in collaboration with Essilor Optic Austria GmbH, that particular medical filters in the range of green-yellow colour especially (565 to 570 nm), and in combination with "Transitions" successfully threat macular degeneration-AMD, slowing down its progression and having positive psychoorganic effect on the depressive mood of such patients with threatened sight. Full attention has been paid to the design of medical filter, so the periphery of the lens plays a positive role in blood concentration of melatonin, while the central part stimulates the sight and the concentration of serotonine. Thus the physiological balance of melatonin and serotonin and the stability of psychophysical disturbances have been achieved.

Designing an Inverter-based Operational Transconductance Amplifier-capacitor Filter with Low Power Consumption for Biomedical Applications

PubMed Central

Yousefinezhad, Sajad; Kermani, Saeed; Hosseinnia, Saeed

2018-01-01

The operational transconductance amplifier-capacitor (OTA-C) filter is one of the best structures for implementing continuous-time filters. It is particularly important to design a universal OTA-C filter capable of generating the desired filter response via a single structure, thus reducing the filter circuit power consumption as well as noise and the occupied space on the electronic chip. In this study, an inverter-based universal OTA-C filter with very low power consumption and acceptable noise was designed with applications in bioelectric and biomedical equipment for recording biomedical signals. The very low power consumption of the proposed filter was achieved through introducing bias in subthreshold MOSFET transistors. The proposed filter is also capable of simultaneously receiving favorable low-, band-, and high-pass filter responses. The performance of the proposed filter was simulated and analyzed via HSPICE software (level 49) and 180 nm complementary metal-oxide-semiconductor technology. The rate of power consumption and noise obtained from simulations are 7.1 nW and 10.18 nA, respectively, so this filter has reduced noise as well as power consumption. The proposed universal OTA-C filter was designed based on the minimum number of transconductance blocks and an inverter circuit by three transconductance blocks (OTA). PMID:29535925

Designing an Inverter-based Operational Transconductance Amplifier-capacitor Filter with Low Power Consumption for Biomedical Applications.

PubMed

Yousefinezhad, Sajad; Kermani, Saeed; Hosseinnia, Saeed

2018-01-01

The operational transconductance amplifier-capacitor (OTA-C) filter is one of the best structures for implementing continuous-time filters. It is particularly important to design a universal OTA-C filter capable of generating the desired filter response via a single structure, thus reducing the filter circuit power consumption as well as noise and the occupied space on the electronic chip. In this study, an inverter-based universal OTA-C filter with very low power consumption and acceptable noise was designed with applications in bioelectric and biomedical equipment for recording biomedical signals. The very low power consumption of the proposed filter was achieved through introducing bias in subthreshold MOSFET transistors. The proposed filter is also capable of simultaneously receiving favorable low-, band-, and high-pass filter responses. The performance of the proposed filter was simulated and analyzed via HSPICE software (level 49) and 180 nm complementary metal-oxide-semiconductor technology. The rate of power consumption and noise obtained from simulations are 7.1 nW and 10.18 nA, respectively, so this filter has reduced noise as well as power consumption. The proposed universal OTA-C filter was designed based on the minimum number of transconductance blocks and an inverter circuit by three transconductance blocks (OTA).

Image denoising by sparse 3-D transform-domain collaborative filtering.

PubMed

Dabov, Kostadin; Foi, Alessandro; Katkovnik, Vladimir; Egiazarian, Karen

2007-08-01

We propose a novel image denoising strategy based on an enhanced sparse representation in transform domain. The enhancement of the sparsity is achieved by grouping similar 2-D image fragments (e.g., blocks) into 3-D data arrays which we call "groups." Collaborative filtering is a special procedure developed to deal with these 3-D groups. We realize it using the three successive steps: 3-D transformation of a group, shrinkage of the transform spectrum, and inverse 3-D transformation. The result is a 3-D estimate that consists of the jointly filtered grouped image blocks. By attenuating the noise, the collaborative filtering reveals even the finest details shared by grouped blocks and, at the same time, it preserves the essential unique features of each individual block. The filtered blocks are then returned to their original positions. Because these blocks are overlapping, for each pixel, we obtain many different estimates which need to be combined. Aggregation is a particular averaging procedure which is exploited to take advantage of this redundancy. A significant improvement is obtained by a specially developed collaborative Wiener filtering. An algorithm based on this novel denoising strategy and its efficient implementation are presented in full detail; an extension to color-image denoising is also developed. The experimental results demonstrate that this computationally scalable algorithm achieves state-of-the-art denoising performance in terms of both peak signal-to-noise ratio and subjective visual quality.

Software for Acoustic Rendering

NASA Technical Reports Server (NTRS)

Miller, Joel D.

2003-01-01

SLAB is a software system that can be run on a personal computer to simulate an acoustic environment in real time. SLAB was developed to enable computational experimentation in which one can exert low-level control over a variety of signal-processing parameters, related to spatialization, for conducting psychoacoustic studies. Among the parameters that can be manipulated are the number and position of reflections, the fidelity (that is, the number of taps in finite-impulse-response filters), the system latency, and the update rate of the filters. Another goal in the development of SLAB was to provide an inexpensive means of dynamic synthesis of virtual audio over headphones, without need for special-purpose signal-processing hardware. SLAB has a modular, object-oriented design that affords the flexibility and extensibility needed to accommodate a variety of computational experiments and signal-flow structures. SLAB s spatial renderer has a fixed signal-flow architecture corresponding to a set of parallel signal paths from each source to a listener. This fixed architecture can be regarded as a compromise that optimizes efficiency at the expense of complete flexibility. Such a compromise is necessary, given the design goal of enabling computational psychoacoustic experimentation on inexpensive personal computers.

Optimally designed narrowband guided-mode resonance reflectance filters for mid-infrared spectroscopy

PubMed Central

Liu, Jui-Nung; Schulmerich, Matthew V.; Bhargava, Rohit; Cunningham, Brian T.

2011-01-01

An alternative to the well-established Fourier transform infrared (FT-IR) spectrometry, termed discrete frequency infrared (DFIR) spectrometry, has recently been proposed. This approach uses narrowband mid-infrared reflectance filters based on guided-mode resonance (GMR) in waveguide gratings, but filters designed and fabricated have not attained the spectral selectivity (≤ 32 cm−1) commonly employed for measurements of condensed matter using FT-IR spectroscopy. With the incorporation of dispersion and optical absorption of materials, we present here optimal design of double-layer surface-relief silicon nitride-based GMR filters in the mid-IR for various narrow bandwidths below 32 cm−1. Both shift of the filter resonance wavelengths arising from the dispersion effect and reduction of peak reflection efficiency and electric field enhancement due to the absorption effect show that the optical characteristics of materials must be taken into consideration rigorously for accurate design of narrowband GMR filters. By incorporating considerations for background reflections, the optimally designed GMR filters can have bandwidth narrower than the designed filter by the antireflection equivalence method based on the same index modulation magnitude, without sacrificing low sideband reflections near resonance. The reported work will enable use of GMR filters-based instrumentation for common measurements of condensed matter, including tissues and polymer samples. PMID:22109445

Contingency designs for attitude determination of TRMM

NASA Technical Reports Server (NTRS)

Crassidis, John L.; Andrews, Stephen F.; Markley, F. Landis; Ha, Kong

1995-01-01

In this paper, several attitude estimation designs are developed for the Tropical Rainfall Measurement Mission (TRMM) spacecraft. A contingency attitude determination mode is required in the event of a primary sensor failure. The final design utilizes a full sixth-order Kalman filter. However, due to initial software concerns, the need to investigate simpler designs was required. The algorithms presented in this paper can be utilized in place of a full Kalman filter, and require less computational burden. These algorithms are based on filtered deterministic approaches and simplified Kalman filter approaches. Comparative performances of all designs are shown by simulating the TRMM spacecraft in mission mode. Comparisons of the simulation results indicate that comparable accuracy with respect to a full Kalman filter design is possible.

Software Would Largely Automate Design of Kalman Filter

NASA Technical Reports Server (NTRS)

Chuang, Jason C. H.; Negast, William J.

2005-01-01

Embedded Navigation Filter Automatic Designer (ENFAD) is a computer program being developed to automate the most difficult tasks in designing embedded software to implement a Kalman filter in a navigation system. The most difficult tasks are selection of error states of the filter and tuning of filter parameters, which are timeconsuming trial-and-error tasks that require expertise and rarely yield optimum results. An optimum selection of error states and filter parameters depends on navigation-sensor and vehicle characteristics, and on filter processing time. ENFAD would include a simulation module that would incorporate all possible error states with respect to a given set of vehicle and sensor characteristics. The first of two iterative optimization loops would vary the selection of error states until the best filter performance was achieved in Monte Carlo simulations. For a fixed selection of error states, the second loop would vary the filter parameter values until an optimal performance value was obtained. Design constraints would be satisfied in the optimization loops. Users would supply vehicle and sensor test data that would be used to refine digital models in ENFAD. Filter processing time and filter accuracy would be computed by ENFAD.

Mechanical design and qualification of IR filter mounts and filter wheel of INSAT-3D sounder for low temperature

NASA Astrophysics Data System (ADS)

Vora, A. P.; Rami, J. B.; Hait, A. K.; Dewan, C. P.; Subrahmanyam, D.; Kirankumar, A. S.

2017-11-01

Next generation Indian Meteorological Satellite will carry Sounder instrument having subsystem of filter wheel measuring Ø260mm and carrying 18 filters arranged in three concentric rings. These filters made from Germanium, are used to separate spectral channels in IR band. Filter wheel is required to be cooled to 214K and rotated at 600 rpm. This Paper discusses the challenges faced in mechanical design of the filter wheel, mainly filter mount design to protect brittle germanium filters from failure under stresses due to very low temperature, compactness of the wheel and casings for improved thermal efficiency, survival under vibration loads and material selection to keep it lighter in weight. Properties of Titanium, Kovar, Invar and Aluminium materials are considered for design. The mount has been designed to accommodate both thermal and dynamic loadings without introducing significant aberrations into the optics or incurring permanent alignment shifts. Detailed finite element analysis of mounts was carried out for stress verification. Results of the qualification tests are discussed for given temperature range of 100K and vibration loads of 12g in Sine and 11.8grms in Random at mount level. Results of the filter wheel qualification as mounted in Electro Optics Module (EOM) are also presented.

Design of efficient circularly symmetric two-dimensional variable digital FIR filters.

PubMed

Bindima, Thayyil; Elias, Elizabeth

2016-05-01

Circularly symmetric two-dimensional (2D) finite impulse response (FIR) filters find extensive use in image and medical applications, especially for isotropic filtering. Moreover, the design and implementation of 2D digital filters with variable fractional delay and variable magnitude responses without redesigning the filter has become a crucial topic of interest due to its significance in low-cost applications. Recently the design using fixed word length coefficients has gained importance due to the replacement of multipliers by shifters and adders, which reduces the hardware complexity. Among the various approaches to 2D design, transforming a one-dimensional (1D) filter to 2D by transformation, is reported to be an efficient technique. In this paper, 1D variable digital filters (VDFs) with tunable cut-off frequencies are designed using Farrow structure based interpolation approach, and the sub-filter coefficients in the Farrow structure are made multiplier-less using canonic signed digit (CSD) representation. The resulting performance degradation in the filters is overcome by using artificial bee colony (ABC) optimization. Finally, the optimized 1D VDFs are mapped to 2D using generalized McClellan transformation resulting in low complexity, circularly symmetric 2D VDFs with real-time tunability.

Design of efficient circularly symmetric two-dimensional variable digital FIR filters

PubMed Central

Bindima, Thayyil; Elias, Elizabeth

2016-01-01

Circularly symmetric two-dimensional (2D) finite impulse response (FIR) filters find extensive use in image and medical applications, especially for isotropic filtering. Moreover, the design and implementation of 2D digital filters with variable fractional delay and variable magnitude responses without redesigning the filter has become a crucial topic of interest due to its significance in low-cost applications. Recently the design using fixed word length coefficients has gained importance due to the replacement of multipliers by shifters and adders, which reduces the hardware complexity. Among the various approaches to 2D design, transforming a one-dimensional (1D) filter to 2D by transformation, is reported to be an efficient technique. In this paper, 1D variable digital filters (VDFs) with tunable cut-off frequencies are designed using Farrow structure based interpolation approach, and the sub-filter coefficients in the Farrow structure are made multiplier-less using canonic signed digit (CSD) representation. The resulting performance degradation in the filters is overcome by using artificial bee colony (ABC) optimization. Finally, the optimized 1D VDFs are mapped to 2D using generalized McClellan transformation resulting in low complexity, circularly symmetric 2D VDFs with real-time tunability. PMID:27222739

Evaluation of film type QX 807 (SO-368, Kodak Ektachrome MS, Estar thin base, with an equivalent Wratten 2A filter overcoat)

NASA Technical Reports Server (NTRS)

Lockwood, H. E.

1975-01-01

A color film with a sensitivity and color balance equal to SO-368, Kodak MS Ektachrome (Estar thin base) was required for use on the Apollo-Soyuz test project (ASTP). A Wratten 2A filter was required for use with the film to reduce short wavelength effects which frequently produce a blue color balance in aerial photographs. The background regarding a special emulsion which was produced with a 2A filter equivalent as an integral part of an SO-368 film manufactured by Eastman Kodak, the cost for production of the special film, and the results of a series of tests made within PTD to certify the film for ASTP use are documented. The tests conducted and documented were physical inspection, process compatibility, effective sensitivity, color balance, cross section analysis, resolution, spectral sensitivity, consistency of results, and picture sample analysis.

Preliminary optical design of PANIC, a wide-field infrared camera for CAHA

NASA Astrophysics Data System (ADS)

Cárdenas, M. C.; Rodríguez Gómez, J.; Lenzen, R.; Sánchez-Blanco, E.

2008-07-01

In this paper, we present the preliminary optical design of PANIC (PAnoramic Near Infrared camera for Calar Alto), a wide-field infrared imager for the Calar Alto 2.2 m telescope. The camera optical design is a folded single optical train that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 μm pixel. A mosaic of four Hawaii 2RG of 2k x 2k made by Teledyne is used as detector and will give a field of view of 31.9 arcmin x 31.9 arcmin. This cryogenic instrument has been optimized for the Y, J, H and K bands. Special care has been taken in the selection of the standard IR materials used for the optics in order to maximize the instrument throughput and to include the z band. The main challenges of this design are: to produce a well defined internal pupil which allows reducing the thermal background by a cryogenic pupil stop; the correction of off-axis aberrations due to the large field available; the correction of chromatic aberration because of the wide spectral coverage; and the capability of introduction of narrow band filters (~1%) in the system minimizing the degradation in the filter passband without a collimated stage in the camera. We show the optomechanical error budget and compensation strategy that allows our as built design to met the performances from an optical point of view. Finally, we demonstrate the flexibility of the design showing the performances of PANIC at the CAHA 3.5m telescope.

Optical Correlation of Images With Signal-Dependent Noise Using Constrained-Modulation Filter Devices

NASA Technical Reports Server (NTRS)

Downie, John D.

1995-01-01

Images with signal-dependent noise present challenges beyond those of images with additive white or colored signal-independent noise in terms of designing the optimal 4-f correlation filter that maximizes correlation-peak signal-to-noise ratio, or combinations of correlation-peak metrics. Determining the proper design becomes more difficult when the filter is to be implemented on a constrained-modulation spatial light modulator device. The design issues involved for updatable optical filters for images with signal-dependent film-grain noise and speckle noise are examined. It is shown that although design of the optimal linear filter in the Fourier domain is impossible for images with signal-dependent noise, proper nonlinear preprocessing of the images allows the application of previously developed design rules for optimal filters to be implemented on constrained-modulation devices. Thus the nonlinear preprocessing becomes necessary for correlation in optical systems with current spatial light modulator technology. These results are illustrated with computer simulations of images with signal-dependent noise correlated with binary-phase-only filters and ternary-phase-amplitude filters.

Thin film-based optically variable security devices: From passive to active

NASA Astrophysics Data System (ADS)

Baloukas, Bill

Counterfeiting costs the world economy billions of dollars every year. Aside from financial losses, counterfeiting also poses a great threat to the public's safety, for example through the existence of counterfeit passports (terrorism), pharmaceutical products (health hazards) and even airplane parts (safety issues). Optical security devices (OSDs) have therefore played a critical role in the fight against counterfeiting. It is the aim of the present thesis to show that through the use of metamerism and electrochromic materials, new types of active security devices with interesting features can be created; indeed, most present-day devices are passive in nature. I first demonstrate that the addition of metamerism in the design of interference filters can result in innovative features. Different structures which can be used in transmission and/or in reflection are designed, fabricated, and evaluated. The first structures which are presented here are based on a combination of two different metameric interference filters. Possessing widely different transmission spectra, these filters also offer different angular color shifts and, as a result, offer an opportunity of creating hidden image effects. Despite their interesting properties, such metameric devices are shown to be highly illuminant and observer sensitive; that is the color match is lost under most observation conditions. These issues are solved by a simpler structure based on the juxtaposition of an interference filter and a non-iridescent colored material. Throughout this study, I present the design approach, analyze the filters' sensitivity to deposition errors, and evaluate the performance of prototype devices prepared by dual ion beam sputtering. Following my work on passive metameric systems, I then propose to go one step further by implementing an active component using an electrochromic material. This novel concept, which is based on the joint use of a metameric filter and electrochromic device, offers the possibility of creating various surprising optical effects. Such a system is obviously more challenging to duplicate due to its complexity, but also adds a second level of authentication accessible to specialized personnel. By designing a metameric filter which matches either the bleached or colored state of an electrochromic device, I show that one can generate two hidden image effects: one which appears when the structure is tilted, and the other one which disappears when the electrochromic material is colored under an applied potential. In this specific study, I present an example of a filter that is metameric with the colored state of a tungsten-oxide-based Deb-type electrochromic device. A hybrid device such as presented in the previous study is clearly interesting from a prototype point of view. Unfortunately, having to design and fabricate two individual components would make such a security feature very expensive. Consequently, my goal was to combine both the color shift and electrochromic color change into a single structure. The following study thus demonstrates, that by designing and fabricating an interference filter based on dense and porous WO3, this goal can be achieved. Finally, a second method of fabricating electrochromic interference filters is proposed which results in a significant decrease in the total numbers of layers of the filters. Replacing the porous WO3 films by a WO 3/SiO2 composite allows for much lower refractive indices to be obtained thus resulting in a larger index contrast (0.61 versus 0.22 in the previous study). In this study, I first explore the physical and electrochromic properties of WO3/SiO2 mixtures. I then combine high and low index films in tandem configurations to observe the bleaching/ coloration dynamics. To account for the poor performance of the ITO|Composite|WO 3 film configuration, I also present an explanation based on the differences in electron diffusion coefficients of the films. I conclude this study with the demonstration of an 11 layer electrochromic interference filter based on the alternation of pure WO3 and (WO3)0.17(SiO 2)0.83 films (with a blue to purple angular color shift) as well as a short discussion on some possible solutions for the observed limitations. (Abstract shortened by UMI.).

Computer-aided design of nano-filter construction using DNA self-assembly

NASA Astrophysics Data System (ADS)

Mohammadzadegan, Reza; Mohabatkar, Hassan

2007-01-01

Computer-aided design plays a fundamental role in both top-down and bottom-up nano-system fabrication. This paper presents a bottom-up nano-filter patterning process based on DNA self-assembly. In this study we designed a new method to construct fully designed nano-filters with the pores between 5 nm and 9 nm in diameter. Our calculations illustrated that by constructing such a nano-filter we would be able to separate many molecules.

Ares-I Bending Filter Design using a Constrained Optimization Approach

NASA Technical Reports Server (NTRS)

Hall, Charles; Jang, Jiann-Woei; Hall, Robert; Bedrossian, Nazareth

2008-01-01

The Ares-I launch vehicle represents a challenging flex-body structural environment for control system design. Software filtering of the inertial sensor output is required to ensure adequate stable response to guidance commands while minimizing trajectory deviations. This paper presents a design methodology employing numerical optimization to develop the Ares-I bending filters. The design objectives include attitude tracking accuracy and robust stability with respect to rigid body dynamics, propellant slosh, and flex. Under the assumption that the Ares-I time-varying dynamics and control system can be frozen over a short period of time, the bending filters are designed to stabilize all the selected frozen-time launch control systems in the presence of parameter uncertainty. To ensure adequate response to guidance command, step response specifications are introduced as constraints in the optimization problem. Imposing these constrains minimizes performance degradation caused by the addition of the bending filters. The first stage bending filter design achieves stability by adding lag to the first structural frequency to phase stabilize the first flex mode while gain stabilizing the higher modes. The upper stage bending filter design gain stabilizes all the flex bending modes. The bending filter designs provided here have been demonstrated to provide stable first and second stage control systems in both Draper Ares Stability Analysis Tool (ASAT) and the MSFC MAVERIC 6DOF nonlinear time domain simulation.

Labyrinth double split open loop resonator based bandpass filter design for S, C and X-band application

NASA Astrophysics Data System (ADS)

Alam, Jubaer; Faruque, Mohammad Rashed Iqbal; Tariqul Islam, Mohammad

2018-07-01

Nested circular shaped Labyrinth double split open loop resonators (OLRs) are introduced in this article to design a triple bandpass filter for 3.01 GHz, 7.39 GHz and 12.88 GHz applications. A Rogers RT-5880 is used as a substrate to design the proposed passband filter which has a succinct structure where the attainment of the resonator is explored both integrally and experimentally. The same structure is designed on both sides of the substrate and an analysis is made on the current distribution. Based on the proposed resonator, a bandpass filter is designed and fabricated to justify the perception focusing on 3.01 GHz, 7.39 GHz and 12.88 GHz. It has also been observed by the Nicolson–Ross–Weir approach at the filtering frequencies. The effective electromagnetic parameters retrieved from the simulation of the S-parameters imply that the OLR metamaterial filter shows negative refraction bands. Having an auspicious design and double negative characteristics, this structure is suitable for triple passband filters, particularly for S, C and X-band applications.

Design of 2.5 GHz broad bandwidth microwave bandpass filter at operating frequency of 10 GHz using HFSS

NASA Astrophysics Data System (ADS)

Jasim, S. E.; Jusoh, M. A.; Mahmud, S. N. S.; Zamani, A. H.

2018-04-01

Development of low losses, small size and broad bandwidth microwave bandpass filter operating at higher frequencies is an active area of research. This paper presents a new route used to design and simulate microwave bandpass filter using finite element modelling and realized broad bandwidth, low losses, small dimension microwave bandpass filter operating at 10 GHz frequency using return loss method. The filter circuit has been carried out using Computer Aid Design (CAD), Ansoft HFSS software and designed with four parallel couple line model and small dimension (10 × 10 mm2) using LaAlO3 substrate. The response of the microwave filter circuit showed high return loss -50 dB at operating frequency at 10.4 GHz and broad bandwidth of 2.5 GHz from 9.5 to 12 GHz. The results indicate the filter design and simulation using HFSS is reliable and have the opportunity to transfer from lab potential experiments to the industry.

An Axiomatic Approach to Hyperconnectivity

NASA Astrophysics Data System (ADS)

Wilkinson, Michael H. F.

In this paper the notion of hyperconnectivity, first put forward by Serra as an extension of the notion of connectivity is explored theoretically. Hyperconnectivity operators, which are the hyperconnected equivalents of connectivity openings are defined, which supports both hyperconnected reconstruction and attribute filters. The new axiomatics yield insight into the relationship between hyperconnectivity and structural morphology. The latter turns out to be a special case of the former, which means a continuum of filters between connected and structural exists, all of which falls into the category of hyperconnected filters.

Specialized Color Targets for Spectral Reflectance Reconstruction of Magnified Images

NASA Astrophysics Data System (ADS)

Kruschwitz, Jennifer D. T.

Digital images are used almost exclusively instead of film to capture visual information across many scientific fields. The colorimetric color representation within these digital images can be relayed from the digital counts produced by the camera with the use of a known color target. In image capture of magnified images, there is currently no reliable color target that can be used at multiple magnifications and give the user a solid understanding of the color ground truth within those images. The first part of this dissertation included the design, fabrication, and testing of a color target produced with optical interference coated microlenses for use in an off-axis illumination, compound microscope. An ideal target was designed to increase the color gamut for colorimetric imaging and provide the necessary "Block Dye" spectral reflectance profiles across the visible spectrum to reduce the number of color patches necessary for multiple filter imaging systems that rely on statistical models for spectral reflectance reconstruction. There are other scientific disciplines that can benefit from a specialized color target to determine the color ground truth in their magnified images and perform spectral estimation. Not every discipline has the luxury of having a multi-filter imaging system. The second part of this dissertation developed two unique ways of using an interference coated color mirror target: one that relies on multiple light-source angles, and one that leverages a dynamic color change with time. The source multi-angle technique would be used for the microelectronic discipline where the reconstructed spectral reflectance would be used to determine a dielectric film thickness on a silicon substrate, and the time varying technique would be used for a biomedical example to determine the thickness of human tear film.

Lumped element filters for electronic warfare systems

NASA Astrophysics Data System (ADS)

Morgan, D.; Ragland, R.

1986-02-01

Increasing demands which future generations of electronic warfare (EW) systems are to satisfy include a reduction in the size of the equipment. The present paper is concerned with lumped element filters which can make a significant contribution to the downsizing of advanced EW systems. Lumped element filter design makes it possible to obtain very small package sizes by utilizing classical low frequency inductive and capacitive components which are small compared to the size of a wavelength. Cost-effective, temperature-stable devices can be obtained on the basis of new design techniques. Attention is given to aspects of design flexibility, an interdigital filter equivalent circuit diagram, conditions for which the use of lumped element filters can be recommended, construction techniques, a design example, and questions regarding the application of lumped element filters to EW processing systems.

General optical discrete z transform: design and application.

PubMed

Ngo, Nam Quoc

2016-12-20

This paper presents a generalization of the discrete z transform algorithm. It is shown that the GOD-ZT algorithm is a generalization of several important conventional discrete transforms. Based on the GOD-ZT algorithm, a tunable general optical discrete z transform (GOD-ZT) processor is synthesized using the silica-based finite impulse response transversal filter. To demonstrate the effectiveness of the method, the design and simulation of a tunable optical discrete Fourier transform (ODFT) processor as a special case of the synthesized GOD-ZT processor is presented. It is also shown that the ODFT processor can function as a real-time optical spectrum analyzer. The tunable ODFT has an important potential application as a tunable optical demultiplexer at the receiver end of an optical orthogonal frequency-division multiplexing transmission system.

Design considerations for a suboptimal Kalman filter

NASA Astrophysics Data System (ADS)

Difilippo, D. J.

1995-06-01

In designing a suboptimal Kalman filter, the designer must decide how to simplify the system error model without causing the filter estimation errors to increase to unacceptable levels. Deletion of certain error states and decoupling of error state dynamics are the two principal model simplifications that are commonly used in suboptimal filter design. For the most part, the decisions as to which error states can be deleted or decoupled are based on the designer's understanding of the physics of the particular system. Consequently, the details of a suboptimal design are usually unique to the specific application. In this paper, the process of designing a suboptimal Kalman filter is illustrated for the case of an airborne transfer-of-alignment (TOA) system used for synthetic aperture radar (SAR) motion compensation. In this application, the filter must continuously transfer the alignment of an onboard Doppler-damped master inertial navigation system (INS) to a strapdown navigator that processes information from a less accurate inertial measurement unit (IMU) mounted on the radar antenna. The IMU is used to measure spurious antenna motion during the SAR imaging interval, so that compensating phase corrections can be computed and applied to the radar returns, thereby presenting image degradation that would otherwise result from such motions. The principles of SAR are described in many references, for instance. The primary function of the TOA Kalman filter in a SAR motion compensation system is to control strapdown navigator attitude errors, and to a less degree, velocity and heading errors. Unlike a classical navigation application, absolute positional accuracy is not important. The motion compensation requirements for SAR imaging are discussed in some detail. This TOA application is particularly appropriate as a vehicle for discussing suboptimal filter design, because the system contains features that can be exploited to allow both deletion and decoupling of error states. In Section 2, a high-level background description of a SAR motion compensation system that incorporates a TOA Kalman filter is given. The optimal TOA filter design is presented in Section 3 with some simulation results to indicate potential filter performance. In Section 4, the suboptimal Kalman filter configuration is derived. Simulation results are also shown in this section to allow comparision between suboptimal and optimal filter performances. Conclusions are contained in Section 5.

A Model-Driven Visualization Tool for Use with Model-Based Systems Engineering Projects

NASA Technical Reports Server (NTRS)

Trase, Kathryn; Fink, Eric

2014-01-01

Model-Based Systems Engineering (MBSE) promotes increased consistency between a system's design and its design documentation through the use of an object-oriented system model. The creation of this system model facilitates data presentation by providing a mechanism from which information can be extracted by automated manipulation of model content. Existing MBSE tools enable model creation, but are often too complex for the unfamiliar model viewer to easily use. These tools do not yet provide many opportunities for easing into the development and use of a system model when system design documentation already exists. This study creates a Systems Modeling Language (SysML) Document Traceability Framework (SDTF) for integrating design documentation with a system model, and develops an Interactive Visualization Engine for SysML Tools (InVEST), that exports consistent, clear, and concise views of SysML model data. These exported views are each meaningful to a variety of project stakeholders with differing subjects of concern and depth of technical involvement. InVEST allows a model user to generate multiple views and reports from a MBSE model, including wiki pages and interactive visualizations of data. System data can also be filtered to present only the information relevant to the particular stakeholder, resulting in a view that is both consistent with the larger system model and other model views. Viewing the relationships between system artifacts and documentation, and filtering through data to see specialized views improves the value of the system as a whole, as data becomes information

On the design of recursive digital filters

NASA Technical Reports Server (NTRS)

Shenoi, K.; Narasimha, M. J.; Peterson, A. M.

1976-01-01

A change of variables is described which transforms the problem of designing a recursive digital filter to that of approximation by a ratio of polynomials on a finite interval. Some analytic techniques for the design of low-pass filters are presented, illustrating the use of the transformation. Also considered are methods for the design of phase equalizers.

Choice of word length in the design of a specialized hardware for lossless wavelet compression of medical images

NASA Astrophysics Data System (ADS)

Urriza, Isidro; Barragan, Luis A.; Artigas, Jose I.; Garcia, Jose I.; Navarro, Denis

1997-11-01

Image compression plays an important role in the archiving and transmission of medical images. Discrete cosine transform (DCT)-based compression methods are not suitable for medical images because of block-like image artifacts that could mask or be mistaken for pathology. Wavelet transforms (WTs) are used to overcome this problem. When implementing WTs in hardware, finite precision arithmetic introduces quantization errors. However, lossless compression is usually required in the medical image field. Thus, the hardware designer must look for the optimum register length that, while ensuring the lossless accuracy criteria, will also lead to a high-speed implementation with small chip area. In addition, wavelet choice is a critical issue that affects image quality as well as system design. We analyze the filters best suited to image compression that appear in the literature. For them, we obtain the maximum quantization errors produced in the calculation of the WT components. Thus, we deduce the minimum word length required for the reconstructed image to be numerically identical to the original image. The theoretical results are compared with experimental results obtained from algorithm simulations on random test images. These results enable us to compare the hardware implementation cost of the different filter banks. Moreover, to reduce the word length, we have analyzed the case of increasing the integer part of the numbers while maintaining constant the word length when the scale increases.

An Isolator System for minimally invasive surgery: the new design

PubMed Central

Jansen, Frank-Willem; Dankelman, Jenny

2010-01-01

Background The risk of obtaining a postsurgical infection depends highly on the air quality surrounding the exposed tissue, surgical instruments, and materials. Many isolators for open surgery have been invented to create a contained sterile volume around the exposed tissue. With the use of an isolator, a surgical procedure can be performed outside sterile environments. The goal of this study was to design an Isolator System (IS) for standard laparoscopic instruments while instrument movements are not restricted. Methods The developed IS consists of a sleeve to protect the instrument shaft and tip and a special balloon to protect the incision and trocar tube. A coupling mechanism connected at the sleeve allows instrument changes without contamination of the isolated parts. Smoke tests were performed to show that outside air does not enter the new IS during a simulated laparoscopic procedure. Eight test runs and one baseline run inside a contained volume filled with thick smoke were performed to investigate whether smoke particles entered the Isolator System. Filters were used to identify smoke entering the Isolator System. Results Seven filters showed no trace of smoke particles. In one test run, a part of the IS loosened and a small brown spot was visible. The filter from the baseline run was completely covered with a thick layer of particles, proving the effectiveness of the test. During all test runs, the isolated instrument was successfully locked on and unlocked from the isolated trocar. Instrument movements gave no complications. After removal of the isolated instrument, it took three novices an average of 3.1 (standard deviation (SD), 0.7) seconds to replace it correctly on the isolated trocar. Conclusions The designed IS for laparoscopy can increase sterility in environments where sterility cannot be guaranteed. The current design is developed for laparoscopy, but it can easily be adapted for other fields in minimally invasive surgery. PMID:20108141

Design-Filter Selection for H2 Control of Microgravity Isolation Systems: A Single-Degree-of-Freedom Case Study

NASA Technical Reports Server (NTRS)

Hampton, R. David; Whorton, Mark S.

2000-01-01

Many microgravity space-science experiments require active vibration isolation, to attain suitably low levels of background acceleration for useful experimental results. The design of state-space controllers by optimal control methods requires judicious choices of frequency-weighting design filters. Kinematic coupling among states greatly clouds designer intuition in the choices of these filters, and the masking effects of the state observations cloud the process further. Recent research into the practical application of H2 synthesis methods to such problems, indicates that certain steps can lead to state frequency-weighting design-filter choices with substantially improved promise of usefulness, even in the face of these difficulties. In choosing these filters on the states, one considers their relationships to corresponding design filters on appropriate pseudo-sensitivity- and pseudo-complementary-sensitivity functions. This paper investigates the application of these considerations to a single-degree-of-freedom microgravity vibration-isolation test case. Significant observations that were noted during the design process are presented. along with explanations based on the existent theory for such problems.

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.

Travelers' Health: Water Disinfection for Travelers

MedlinePlus

... hand-pump or gravity-drip filters with various designs and types of filter media are commercially available ... salts, thus achieving desalination. One new portable filter design incorporates hollow fiber technology, which is a cluster ...

Design of Microstrip Bandpass Filters Using SIRs with Even-Mode Harmonics Suppression for Cellular Systems

NASA Astrophysics Data System (ADS)

Theerawisitpong, Somboon; Suzuki, Toshitatsu; Morita, Noboru; Utsumi, Yozo

The design of microstrip bandpass filters using stepped-impedance resonators (SIRs) is examined. The passband center frequency for the WCDMA-FDD (uplink band) Japanese cellular system is 1950MHz with a 60-MHz bandwidth. The SIR physical characteristic can be designed using a SIR characteristic chart based on second harmonic suppression. In our filter design, passband design charts were obtained through the design procedure. Tchebycheff and maximally flat bandpass filters of any bandwidth and any number of steps can be designed using these passband design charts. In addition, sharp skirt characteristics in the passband can be realized by having two transmission zeros at both adjacent frequency bands by using open-ended quarter-wavelength stubs at input and output ports. A new even-mode harmonics suppression technique is proposed to enable a wide rejection band having a high suppression level. The unloaded quality factor of the resonator used in the proposed filters is greater than 240.

Pattern recognition with composite correlation filters designed with multi-object combinatorial optimization

DOE PAGES

Awwal, Abdul; Diaz-Ramirez, Victor H.; Cuevas, Andres; ...

2014-10-23

Composite correlation filters are used for solving a wide variety of pattern recognition problems. These filters are given by a combination of several training templates chosen by a designer in an ad hoc manner. In this work, we present a new approach for the design of composite filters based on multi-objective combinatorial optimization. Given a vast search space of training templates, an iterative algorithm is used to synthesize a filter with an optimized performance in terms of several competing criteria. Furthermore, by employing a suggested binary-search procedure a filter bank with a minimum number of filters can be constructed, formore » a prespecified trade-off of performance metrics. Computer simulation results obtained with the proposed method in recognizing geometrically distorted versions of a target in cluttered and noisy scenes are discussed and compared in terms of recognition performance and complexity with existing state-of-the-art filters.« less

Pattern recognition with composite correlation filters designed with multi-object combinatorial optimization

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

Awwal, Abdul; Diaz-Ramirez, Victor H.; Cuevas, Andres

Composite correlation filters are used for solving a wide variety of pattern recognition problems. These filters are given by a combination of several training templates chosen by a designer in an ad hoc manner. In this work, we present a new approach for the design of composite filters based on multi-objective combinatorial optimization. Given a vast search space of training templates, an iterative algorithm is used to synthesize a filter with an optimized performance in terms of several competing criteria. Furthermore, by employing a suggested binary-search procedure a filter bank with a minimum number of filters can be constructed, formore » a prespecified trade-off of performance metrics. Computer simulation results obtained with the proposed method in recognizing geometrically distorted versions of a target in cluttered and noisy scenes are discussed and compared in terms of recognition performance and complexity with existing state-of-the-art filters.« less

Selection vector filter framework

NASA Astrophysics Data System (ADS)

Lukac, Rastislav; Plataniotis, Konstantinos N.; Smolka, Bogdan; Venetsanopoulos, Anastasios N.

2003-10-01

We provide a unified framework of nonlinear vector techniques outputting the lowest ranked vector. The proposed framework constitutes a generalized filter class for multichannel signal processing. A new class of nonlinear selection filters are based on the robust order-statistic theory and the minimization of the weighted distance function to other input samples. The proposed method can be designed to perform a variety of filtering operations including previously developed filtering techniques such as vector median, basic vector directional filter, directional distance filter, weighted vector median filters and weighted directional filters. A wide range of filtering operations is guaranteed by the filter structure with two independent weight vectors for angular and distance domains of the vector space. In order to adapt the filter parameters to varying signal and noise statistics, we provide also the generalized optimization algorithms taking the advantage of the weighted median filters and the relationship between standard median filter and vector median filter. Thus, we can deal with both statistical and deterministic aspects of the filter design process. It will be shown that the proposed method holds the required properties such as the capability of modelling the underlying system in the application at hand, the robustness with respect to errors in the model of underlying system, the availability of the training procedure and finally, the simplicity of filter representation, analysis, design and implementation. Simulation studies also indicate that the new filters are computationally attractive and have excellent performance in environments corrupted by bit errors and impulsive noise.

The Stable Solar Analyzer

NASA Technical Reports Server (NTRS)

Rust, D. M.; Appourchaux, T.

1988-01-01

Progress in the development of an instrument with very high (1:10 billion) wavelength stability designed to measure solar surface velocities and magnetic fields is reported. The instrument determines Doppler and Zeeman shifts in solar spectral lines by a 6-point weighted average. It is built around an electrically tunable solid lithium-niobate Fabry-Perot etalon that is stabilized against a diode laser which itself is locked to a resonance line of cesium 133. Key features are the etalon, which acts as a wide-angle 0.017-nm solar filter, the camera with a specially stabilized shutter, and the instrument control and data collection system. Use of the instrument in helioseismological research is emphasized.

TU-CD-207-10: Dedicated Cone-Beam Breast CT: Design of a 3-D Beam-Shaping Filter

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

Vedantham, S; Shi, L; Karellas, A

2015-06-15

Purpose: To design a 3 -D beam-shaping filter for cone-beam breast CT for equalizing x-ray photon fluence incident on the detector along both fan and cone angle directions. Methods: The 3-D beam-shaping filter was designed as the sum of two filters: a bow-tie filter assuming cylindrical breast and a 3D difference filter equivalent to the difference in projected thickness between the cylinder and the real breast. Both filters were designed with breast-equivalent material and converted to Al for the targeted x-ray spectrum. The bow-tie was designed for the largest diameter cylindrical breast by determining the fan-angle dependent path-length and themore » filter thickness needed to equalize the fluence. A total of 23,760 projections (180 projections of 132 binary breast CT volumes) were averaged, scaled for the largest breast, and subtracted from the projection of the largest diameter cylindrical breast to provide the 3D difference filter. The 3 -D beam shaping filter was obtained by summing the two filters. Numerical simulations with semi-ellipsoidal breasts of 10–18 cm diameter (chest-wall to nipple length=0.75 x diameter) were conducted to evaluate beam equalization. Results: The proposed 3-D beam-shaping filter showed a 140% -300% improvement in equalizing the photon fluence along the chest-wall to nipple (cone-angle) direction compared to a bow-tie filter. The improvement over bow-tie filter was larger for breasts with longer chest-wall to nipple length. Along the radial (fan-angle) direction, the performance of the 3-D beam shaping filter was marginally better than the bow-tie filter, with 4%-10% improvement in equalizing the photon fluence. For a ray traversing the chest-wall diameter of the breast, the filter transmission ratio was >0.95. Conclusion: The 3-D beam shaping filter provided substantial advantage over bow-tie filter in equalizing the photon fluence along the cone-angle direction. In conjunction with a 2-axis positioner, the filter can accommodate breasts of varying dimensions and chest-wall inclusion. Supported in part by NIH R01 CA128906 and R21 CA134128. The contents are solely the responsibility of the authors and do not reflect the official views of the NIH or NCI.« less

GPU-based parallel algorithm for blind image restoration using midfrequency-based methods

NASA Astrophysics Data System (ADS)

Xie, Lang; Luo, Yi-han; Bao, Qi-liang

2013-08-01

GPU-based general-purpose computing is a new branch of modern parallel computing, so the study of parallel algorithms specially designed for GPU hardware architecture is of great significance. In order to solve the problem of high computational complexity and poor real-time performance in blind image restoration, the midfrequency-based algorithm for blind image restoration was analyzed and improved in this paper. Furthermore, a midfrequency-based filtering method is also used to restore the image hardly with any recursion or iteration. Combining the algorithm with data intensiveness, data parallel computing and GPU execution model of single instruction and multiple threads, a new parallel midfrequency-based algorithm for blind image restoration is proposed in this paper, which is suitable for stream computing of GPU. In this algorithm, the GPU is utilized to accelerate the estimation of class-G point spread functions and midfrequency-based filtering. Aiming at better management of the GPU threads, the threads in a grid are scheduled according to the decomposition of the filtering data in frequency domain after the optimization of data access and the communication between the host and the device. The kernel parallelism structure is determined by the decomposition of the filtering data to ensure the transmission rate to get around the memory bandwidth limitation. The results show that, with the new algorithm, the operational speed is significantly increased and the real-time performance of image restoration is effectively improved, especially for high-resolution images.

Report of Operation FITZWILLIAM. Volume 2. Nuclear Detection by Airborne Filters

DTIC Science & Technology

1948-01-01

filter device w.a~ designed so as to expoBe a pai,r or filter papers simultaneous:ty. 10ne in each side of th.$ assembly.. The un11;. vaa mounted...m:inut.e at the normal cruising ~:rpeed of’ the air- eril!t. The filter devi1r.:e ~ras designed to operate on the veQ.turi. pri:ncipl,e. 6 Comparison...radioactivity by a spt!c1.al vrap-around Gei ger-MueUer ccunter designed specifically for ~~s purpo~e. Measur ed acti vitjes of filter papers at any one

First Light for Mimir, a Near-Infrared Wide-Field Imager, Spectrometer, and Polarimeter for the Perkins Telescope

NASA Astrophysics Data System (ADS)

Clemens, D. P.; Sarcia, D.; Tollestrup, E. V.; Grabau, A.; Bosh, A.; Buie, M.; Taylor, B.; Dunham, E.

2004-12-01

The Mimir instrument completed its 5-year development in our Boston University lab and was delivered this past July to Flagstaff, Arizona and the Perkins telescope for commissioning. Mimir is a "facility-class" multi-function near-infrared imager, spectrometer, and polarimeter developed under a joint program by Boston University and Lowell Observatory scientists, staff, and engineers. It fully covers the wavelength range 1-5 microns onto its 1024x1024 Aladdin III InSb array detector. In its wide-field imaging mode, a 10x10 arcmin field is sampled at 0.6 arcsec per pixel. In its narrow-field mode, the field is 3x3 arcmin, sampled at 0.2 arcsec per pixel. A full complement of JHKsL'M' broad-band filters are present in its four filter wheels. Spectroscopy is accomplished using a matched slit-plate and selector system, three grisms, and special spectroscopy filters (for order suppression). Polarimetry is accomplished using rotating half-wave plates and a fixed wire grid. All of these modes were certified in the lab; all have been certified at the Perkins telescope during the August/September commissioning run. Mode switches are accomplished in a matter of only seconds, making Mimir exceedingly versatile. The poster highlights the designs and components of Mimir as well as examples of images, spectra, and polarimetry from the commissioning telescope runs this past fall. Internal, shared-risk observations with Mimir begin this quarter. Mimir design and development has been funded by NASA, NSF, and the W.M. Keck Foundation.

Fast estimate of Hartley entropy in image sharpening

NASA Astrophysics Data System (ADS)

Krbcová, Zuzana; Kukal, Jaromír.; Svihlik, Jan; Fliegel, Karel

2016-09-01

Two classes of linear IIR filters: Laplacian of Gaussian (LoG) and Difference of Gaussians (DoG) are frequently used as high pass filters for contextual vision and edge detection. They are also used for image sharpening when linearly combined with the original image. Resulting sharpening filters are radially symmetric in spatial and frequency domains. Our approach is based on the radial approximation of unknown optimal filter, which is designed as a weighted sum of Gaussian filters with various radii. The novel filter is designed for MRI image enhancement where the image intensity represents anatomical structure plus additive noise. We prefer the gradient norm of Hartley entropy of whole image intensity as a measure which has to be maximized for the best sharpening. The entropy estimation procedure is as fast as FFT included in the filter but this estimate is a continuous function of enhanced image intensities. Physically motivated heuristic is used for optimum sharpening filter design by its parameter tuning. Our approach is compared with Wiener filter on MRI images.

Analysis of Local Structure, Chemistry and Bonding by Electron Energy Loss Spectroscopy

NASA Astrophysics Data System (ADS)

Mayer, Joachim

In the present chapter, the reader will first be introduced briefly to the basic principles of analytical transmission electron microscopy (ATEM) with special emphasis on electron energy-loss spectroscopy (EELS) and energy-filtering TEM. The quantification of spectra to obtain chemical information and the origin and interpretation of near-edge fine structures in EELS (ELNES) are discussed. Special attention will be given to the characterization of internal interfaces and the literature in this area will be reviewed. Selected examples of the application of ATEM in the investigation of internal interfaces will be given. These examples include both EELS in the energy-filtering TEM and in the scanning transmission electron microscope (STEM).

Tracking with time-delayed data in multisensor systems

NASA Astrophysics Data System (ADS)

Hilton, Richard D.; Martin, David A.; Blair, William D.

1993-08-01

When techniques for target tracking are expanded to make use of multiple sensors in a multiplatform system, the possibility of time delayed data becomes a reality. When a discrete-time Kalman filter is applied and some of the data entering the filter are delayed, proper processing of these late data is a necessity for obtaining an optimal estimate of a target's state. If this problem is not given special care, the quality of the state estimates can be degraded relative to that quality provided by a single sensor. A negative-time update technique is developed using the criteria of minimum mean-square error (MMSE) under the constraint that only the results of the most recent update are saved. The performance of the MMSE technique is compared to that of the ad hoc approach employed in the Cooperative Engagement Capabilities (CEC) system for processing data from multiple platforms. It was discovered that the MMSE technique is a stable solution to the negative-time update problem, while the CEC technique was found to be less than desirable when used with filters designed for tracking highly maneuvering targets at relatively low data rates. The MMSE negative-time update technique was found to be a superior alternative to the existing CEC negative-time update technique.

Image reconstruction of x-ray tomography by using image J platform

NASA Astrophysics Data System (ADS)

Zain, R. M.; Razali, A. M.; Salleh, K. A. M.; Yahya, R.

2017-01-01

A tomogram is a technical term for a CT image. It is also called a slice because it corresponds to what the object being scanned would look like if it were sliced open along a plane. A CT slice corresponds to a certain thickness of the object being scanned. So, while a typical digital image is composed of pixels, a CT slice image is composed of voxels (volume elements). In the case of x-ray tomography, similar to x-ray Radiography, the quantity being imaged is the distribution of the attenuation coefficient μ(x) within the object of interest. The different is only on the technique to produce the tomogram. The image of x-ray radiography can be produced straight foward after exposed to x-ray, while the image of tomography produces by combination of radiography images in every angle of projection. A number of image reconstruction methods by converting x-ray attenuation data into a tomography image have been produced by researchers. In this work, Ramp filter in "filtered back projection" has been applied. The linear data acquired at each angular orientation are convolved with a specially designed filter and then back projected across a pixel field at the same angle. This paper describe the step of using Image J software to produce image reconstruction of x-ray tomography.

On the relationship between matched filter theory as applied to gust loads and phased design loads analysis

NASA Technical Reports Server (NTRS)

Zeiler, Thomas A.; Pototzky, Anthony S.

1989-01-01

A theoretical basis and example calculations are given that demonstrate the relationship between the Matched Filter Theory approach to the calculation of time-correlated gust loads and Phased Design Load Analysis in common use in the aerospace industry. The relationship depends upon the duality between Matched Filter Theory and Random Process Theory and upon the fact that Random Process Theory is used in Phased Design Loads Analysis in determining an equiprobable loads design ellipse. Extensive background information describing the relevant points of Phased Design Loads Analysis, calculating time-correlated gust loads with Matched Filter Theory, and the duality between Matched Filter Theory and Random Process Theory is given. It is then shown that the time histories of two time-correlated gust load responses, determined using the Matched Filter Theory approach, can be plotted as parametric functions of time and that the resulting plot, when superposed upon the design ellipse corresponding to the two loads, is tangent to the ellipse. The question is raised of whether or not it is possible for a parametric load plot to extend outside the associated design ellipse. If it is possible, then the use of the equiprobable loads design ellipse will not be a conservative design practice in some circumstances.

Optimal design of a bank of spatio-temporal filters for EEG signal classification.

PubMed

Higashi, Hiroshi; Tanaka, Toshihisa

2011-01-01

The spatial weights for electrodes called common spatial pattern (CSP) are known to be effective in EEG signal classification for motor imagery based brain computer interfaces (MI-BCI). To achieve accurate classification in CSP, the frequency filter should be properly designed. To this end, several methods for designing the filter have been proposed. However, the existing methods cannot consider plural brain activities described with different frequency bands and different spatial patterns such as activities of mu and beta rhythms. In order to efficiently extract these brain activities, we propose a method to design plural filters and spatial weights which extract desired brain activity. The proposed method designs finite impulse response (FIR) filters and the associated spatial weights by optimization of an objective function which is a natural extension of CSP. Moreover, we show by a classification experiment that the bank of FIR filters which are designed by introducing an orthogonality into the objective function can extract good discriminative features. Moreover, the experiment result suggests that the proposed method can automatically detect and extract brain activities related to motor imagery.

Imaging IR spectrometer, phase 2

NASA Technical Reports Server (NTRS)

Gradie, Jonathan; Lewis, Ralph; Lundeen, Thomas; Wang, Shu-I

1990-01-01

The development is examined of a prototype multi-channel infrared imaging spectrometer. The design, construction and preliminary performance is described. This instrument is intended for use with JPL Table Mountain telescope as well as the 88 inch UH telescope on Mauna Kea. The instrument is capable of sampling simultaneously the spectral region of 0.9 to 2.6 um at an average spectral resolution of 1 percent using a cooled (77 K) optical bench, a concave holographic grating and a special order sorting filter to allow the acquisition of the full spectral range on a 128 x 128 HgCdTe infrared detector array. The field of view of the spectrometer is 0.5 arcsec/pixel in mapping mode and designed to be 5 arcsec/pixel in spot mode. The innovative optical design has resulted in a small, transportable spectrometer, capable of remote operation. Commercial applications of this spectrometer design include remote sensing from both space and aircraft platforms as well as groundbased astronomical observations.

Tracking control of air-breathing hypersonic vehicles with non-affine dynamics via improved neural back-stepping design.

PubMed

Bu, Xiangwei; He, Guangjun; Wang, Ke

2018-04-01

This study considers the design of a new back-stepping control approach for air-breathing hypersonic vehicle (AHV) non-affine models via neural approximation. The AHV's non-affine dynamics is decomposed into velocity subsystem and altitude subsystem to be controlled separately, and robust adaptive tracking control laws are developed using improved back-stepping designs. Neural networks are applied to estimate the unknown non-affine dynamics, which guarantees the addressed controllers with satisfactory robustness against uncertainties. In comparison with the existing control methodologies, the special contributions are that the non-affine issue is handled by constructing two low-pass filters based on model transformations, and virtual controllers are treated as intermediate variables such that they aren't needed for back-stepping designs any more. Lyapunov techniques are employed to show the uniformly ultimately boundedness of all closed-loop signals. Finally, simulation results are presented to verify the tracking performance and superiorities of the investigated control strategy. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Design and Simulation of Microstrip Hairpin Bandpass Filter with Open Stub and Defected Ground Structure (DGS) at X-Band Frequency

NASA Astrophysics Data System (ADS)

Hariyadi, T.; Mulyasari, S.; Mukhidin

2018-02-01

In this paper we have designed and simulated a Band Pass Filter (BPF) at X-band frequency. This filter is designed for X-band weather radar application with 9500 MHz center frequency and bandwidth -3 dB is 120 MHz. The filter design was performed using a hairpin microstrip combined with an open stub and defected ground structure (DGS). The substrate used is Rogers RT5880 with a dielectric constant of 2.2 and a thickness of 1.575 mm. Based on the simulation results, it is found that the filter works on frequency 9,44 - 9,56 GHz with insertion loss value at pass band is -1,57 dB.

Optimal design of FIR triplet halfband filter bank and application in image coding.

PubMed

Kha, H H; Tuan, H D; Nguyen, T Q

2011-02-01

This correspondence proposes an efficient semidefinite programming (SDP) method for the design of a class of linear phase finite impulse response triplet halfband filter banks whose filters have optimal frequency selectivity for a prescribed regularity order. The design problem is formulated as the minimization of the least square error subject to peak error constraints and regularity constraints. By using the linear matrix inequality characterization of the trigonometric semi-infinite constraints, it can then be exactly cast as a SDP problem with a small number of variables and, hence, can be solved efficiently. Several design examples of the triplet halfband filter bank are provided for illustration and comparison with previous works. Finally, the image coding performance of the filter bank is presented.

Mode-filtered large-core fiber for optical coherence tomography

PubMed Central

Moon, Sucbei; Chen, Zhongping

2013-01-01

We have investigated the use of multimode fiber in optical coherence tomography (OCT) with a mode filter that selectively suppresses the power of the high-order modes (HOMs). A large-core fiber (LCF) that has a moderate number of guiding modes was found to be an attractive alternative to the conventional single-mode fiber for its large mode area and the consequentially wide Rayleigh range of the output beam if the HOMs of the LCF were efficiently filtered out by a mode filter installed in the middle. For this, a simple mode filtering scheme of a fiber-coil mode filter was developed in this study. The LCF was uniformly coiled by an optimal bend radius with a fiber winder, specially devised for making a low-loss mode filter. The feasibility of the mode-filtered LCF in OCT imaging was tested with a common-path OCT system. It has been successfully demonstrated that our mode-filtered LCF can provide a useful imaging or sensing probe without an objective lens that greatly simplifies the structure of the probing optics. PMID:23207399

System reliability analysis of granular filter for protection against piping in dams

NASA Astrophysics Data System (ADS)

Srivastava, A.; Sivakumar Babu, G. L.

2015-09-01

Granular filters are provided for the safety of water retaining structure for protection against piping failure. The phenomenon of piping triggers when the base soil to be protected starts migrating in the direction of seepage flow under the influence of seepage force. To protect base soil from migration, the voids in the filter media should be small enough but it should not also be too small to block smooth passage of seeping water. Fulfilling these two contradictory design requirements at the same time is a major concern for the successful performance of granular filter media. Since Terzaghi era, conventionally, particle size distribution (PSD) of granular filters is designed based on particle size distribution characteristics of the base soil to be protected. The design approach provides a range of D15f value in which the PSD of granular filter media should fall and there exist infinite possibilities. Further, safety against the two critical design requirements cannot be ensured. Although used successfully for many decades, the existing filter design guidelines are purely empirical in nature accompanied with experience and good engineering judgment. In the present study, analytical solutions for obtaining the factor of safety with respect to base soil particle migration and soil permeability consideration as proposed by the authors are first discussed. The solution takes into consideration the basic geotechnical properties of base soil and filter media as well as existing hydraulic conditions and provides a comprehensive solution to the granular filter design with ability to assess the stability in terms of factor of safety. Considering the fact that geotechnical properties are variable in nature, probabilistic analysis is further suggested to evaluate the system reliability of the filter media that may help in risk assessment and risk management for decision making.

Inverse design of high-Q wave filters in two-dimensional phononic crystals by topology optimization.

PubMed

Dong, Hao-Wen; Wang, Yue-Sheng; Zhang, Chuanzeng

2017-04-01

Topology optimization of a waveguide-cavity structure in phononic crystals for designing narrow band filters under the given operating frequencies is presented in this paper. We show that it is possible to obtain an ultra-high-Q filter by only optimizing the cavity topology without introducing any other coupling medium. The optimized cavity with highly symmetric resonance can be utilized as the multi-channel filter, raising filter and T-splitter. In addition, most optimized high-Q filters have the Fano resonances near the resonant frequencies. Furthermore, our filter optimization based on the waveguide and cavity, and our simple illustration of a computational approach to wave control in phononic crystals can be extended and applied to design other acoustic devices or even opto-mechanical devices. Copyright © 2016 Elsevier B.V. All rights reserved.

A design aid for determining width of filter strips

Treesearch

M.G. Dosskey; M.J. Helmers; D.E. Eisenhauer

2008-01-01

watershed planners need a tool for determining width of filter strips that is accurate enough for developing cost-effective site designs and easy enough to use for making quick determinations on a large number and variety of sites.This study employed the process-based Vegetative Filter Strip Model to evaluate the relationship between filter strip width and trapping...

Design and Analysis of a Micromachined LC Low Pass Filter For 2.4GHz Application

NASA Astrophysics Data System (ADS)

Saroj, Samruddhi R.; Rathee, Vishal R.; Pande, Rajesh S.

2018-02-01

This paper reports design and analysis of a passive low pass filter with cut-off frequency of 2.4 GHz using MEMS (Micro Electro-Mechanical Systems) technology. The passive components such as suspended spiral inductors and metal-insulator-metal (MIM) capacitor are arranged in T network form to implement LC low pass filter design. This design employs a simple approach of suspension thereby reducing parasitic losses to eliminate the performance degrading effects caused by integrating an off-chip inductor in the filter circuit proposed to be developed on a low cost silicon substrate using RF-MEMS components. The filter occupies only 2.1 mm x 0.66 mm die area and is designed using micro-strip transmission line placed on a silicon substrate. The design is implemented in High Frequency Structural Simulator (HFSS) software and fabrication flow is proposed for its implementation. The simulated results show that the design has an insertion loss of -4.98 dB and return loss of -2.60dB.

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.

The Lockheed alternate partial polarizer universal filter

NASA Technical Reports Server (NTRS)

Title, A. M.

1976-01-01

A tunable birefringent filter using an alternate partial polarizer design has been built. The filter has a transmission of 38% in polarized light. Its full width at half maximum is .09A at 5500A. It is tunable from 4500 to 8500A by means of stepping motor actuated rotating half wave plates and polarizers. Wave length commands and thermal compensation commands are generated by a PPD 11/10 minicomputer. The alternate partial polarizer universal filter is compared with the universal birefringent filter and the design techniques, construction methods, and filter performance are discussed in some detail. Based on the experience of this filter some conclusions regarding the future of birefringent filters are elaborated.

A transmission-line model of back-cavity dynamics for in-plane pressure-differential microphones.

PubMed

Kim, Donghwan; Kuntzman, Michael L; Hall, Neal A

2014-11-01

Pressure-differential microphones inspired by the hearing mechanism of a special parasitoid fly have been described previously. The designs employ a beam structure that rotates about two pivots over an enclosed back volume. The back volume is only partially enclosed due to open slits around the perimeter of the beam. The open slits enable incoming sound waves to affect the pressure profile in the microphone's back volume. The goal of this work is to study the net moment applied to pressure-differential microphones by an incoming sound wave, which in-turn requires modeling the acoustic pressure distribution within the back volume. A lumped-element distributed transmission-line model of the back volume is introduced for this purpose. It is discovered that the net applied moment follows a low-pass filter behavior such that, at frequencies below a corner frequency depending on geometrical parameters of the design, the applied moment is unaffected by the open slits. This is in contrast to the high-pass filter behavior introduced by barometric pressure vents in conventional omnidirectional microphones. The model accurately predicts observed curvature in the frequency response of a prototype pressure-differential microphone 2 mm × 1 mm × 0.5 mm in size and employing piezoelectric readout.

Reduction of radiation exposure during radiography for scoliosis

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

Gray, J.E.; Hoffman, A.D.; Peterson, H.A.

1983-01-01

To reduce the radiation exposure received by young scoliosis patients during treatment, six changes in technique were instituted: (1) a posteroanterior projection, (2) specially designed leaded acrylic filters, (3) a high-speed screen-film system, (4) a specially designed cassette-holder and grid, (5) a breast-shield, and (6) additional filtration in the x-ray tube the thyroid, breast, and abdominal areas were made on an Alderson phantom. They revealed an eightfold reduction in abdominal exposure for both the posteroanterior and the lateral radiographys. There was a twentyfold reduction in exposure to the thyroid for the posteroanterior radiography from 100 to less than five milliroentgensmore » and for the lateral radiograph there was a 100-fold reduction from 618 to six milliroentgens. For the breasts there was a sixty-ninefold reduction from 344 to less than five milliroentgens for the posteroanterior radiography and a fifty-fivefold reduction from 277 to less than five milliroentgens for the lateral radiograph. These reductions in exposure were obtained without significant loss in the quality of the radiographs and in most instances with an improvement in the over-all quality of the radiograph due to the more uniform exposure.« less

Improvement of sand filter and constructed wetland design using an environmental decision support system.

PubMed

Turon, Clàudia; Comas, Joaquim; Torrens, Antonina; Molle, Pascal; Poch, Manel

2008-01-01

With the aim of improving effluent quality of waste stabilization ponds, different designs of vertical flow constructed wetlands and intermittent sand filters were tested on an experimental full-scale plant within the framework of a European project. The information extracted from this study was completed and updated with heuristic and bibliographic knowledge. The data and knowledge acquired were difficult to integrate into mathematical models because they involve qualitative information and expert reasoning. Therefore, it was decided to develop an environmental decision support system (EDSS-Filter-Design) as a tool to integrate mathematical models and knowledge-based techniques. This paper describes the development of this support tool, emphasizing the collection of data and knowledge and representation of this information by means of mathematical equations and a rule-based system. The developed support tool provides the main design characteristics of filters: (i) required surface, (ii) media type, and (iii) media depth. These design recommendations are based on wastewater characteristics, applied load, and required treatment level data provided by the user. The results of the EDSS-Filter-Design provide appropriate and useful information and guidelines on how to design filters, according to the expert criteria. The encapsulation of the information into a decision support system reduces the design period and provides a feasible, reasoned, and positively evaluated proposal.

Calibration sources and filters of the soft x-ray spectrometer instrument on the Hitomi spacecraft

NASA Astrophysics Data System (ADS)

de Vries, Cor P.; Haas, Daniel; Yamasaki, Noriko Y.; Herder, Jan-Willem den; Paltani, Stephane; Kilbourne, Caroline; Tsujimoto, Masahiro; Eckart, Megan E.; Leutenegger, Maurice A.; Costantini, Elisa; Dercksen, Johannes P. C.; Dubbeldam, Luc; Frericks, Martin; Laubert, Phillip P.; van Loon, Sander; Lowes, Paul; McCalden, Alec J.; Porter, Frederick S.; Ruijter, Jos; Wolfs, Rob

2018-01-01

The soft x-ray spectrometer was designed to operate onboard the Japanese Hitomi (ASTRO-H) satellite. In the beam of this instrument, there was a filter wheel containing x-ray filters and active calibration sources. This paper describes this filter wheel. We show the purpose of the filters and the preflight calibrations performed. In addition, we present the calibration source design and measured performance. Finally, we conclude with prospects for future missions.

Boundary implications for frequency response of interval FIR and IIR filters

NASA Technical Reports Server (NTRS)

Bose, N. K.; Kim, K. D.

1991-01-01

It is shown that vertex implication results in parameter space apply to interval trigonometric polynomials. Subsequently, it is shown that the frequency responses of both interval FIR and IIR filters are bounded by the frequency responses of certain extreme filters. The results apply directly in the evaluation of properties of designed filters, especially because it is more realistic to bound the filter coefficients from above and below instead of determining those with infinite precision because of finite arithmetic effects. Illustrative examples are provided to show how the extreme filters might be easily derived in any specific interval FIR or IIR filter design problem.

A Critical Review of Available Retrievable Inferior Vena Cava Filters and Future Directions

PubMed Central

Montgomery, Jennifer P.; Kaufman, John A.

2016-01-01

Inferior vena cava filters have been placed in patients for decades for protection against pulmonary embolism. The widespread use of filters has dramatically increased owing at least in part to the approval of retrievable vena cava filters. Retrievable filters have the potential to protect against pulmonary embolism and then be retrieved once no longer needed to avoid potential long-term complications. There are several retrievable vena cava filters available for use. This article discusses the different filter designs as well as the published data on these available filters. When selecting a filter for use, it is important to consider the potential short-term complications and the filters' window for retrieval. Understanding potential long-term complications is also critical, as these devices are approved for permanent placement and many filters are not retrieved. Finally, this article will address research into new designs that may be the future of vena cava filtration. PMID:27247475

A Critical Review of Available Retrievable Inferior Vena Cava Filters and Future Directions.

PubMed

Montgomery, Jennifer P; Kaufman, John A

2016-06-01

Inferior vena cava filters have been placed in patients for decades for protection against pulmonary embolism. The widespread use of filters has dramatically increased owing at least in part to the approval of retrievable vena cava filters. Retrievable filters have the potential to protect against pulmonary embolism and then be retrieved once no longer needed to avoid potential long-term complications. There are several retrievable vena cava filters available for use. This article discusses the different filter designs as well as the published data on these available filters. When selecting a filter for use, it is important to consider the potential short-term complications and the filters' window for retrieval. Understanding potential long-term complications is also critical, as these devices are approved for permanent placement and many filters are not retrieved. Finally, this article will address research into new designs that may be the future of vena cava filtration.

Hard X-ray Wiggler Front End Filter Design

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

Schulte-Schrepping, Horst; Hahn, Ulrich

2007-01-19

The front end filter design and implementation for the new HARWI-II hard X-ray wiggler at DORIS-III at HASYLAB/DESY is presented. The device emits a total power of 30 kW at 150mA storage ring current. The beam has a horizontal width of 3.8mrad and a central power density of 54 W/mm2 at 26m distance to the source. The filter section located in the ring tunnel has been introduced to tailor the thermal loads at the downstream optical components. The high power density and the high total power at the filter section are handled with a layered design. Glassy carbon filters convertmore » the absorbed power into thermal radiation to lower the heat load to an acceptable level for water cooled copper filters. The requirements in beam size and filtering are addressed by separating the filter functions in three units which are switched individually into the beam.« less

Media filter drain : modified design evaluation and existing design longevity evaluation.

DOT National Transportation Integrated Search

2014-02-01

The media filter drain (MFD), a stormwater water quality treatment best management practice, consists of media made up of : aggregate, perlite, gypsum and dolomite in a trench located along roadway shoulders with gravel and vegetative pre-filtering :...

An improved design method based on polyphase components for digital FIR filters

NASA Astrophysics Data System (ADS)

Kumar, A.; Kuldeep, B.; Singh, G. K.; Lee, Heung No

2017-11-01

This paper presents an efficient design of digital finite impulse response (FIR) filter, based on polyphase components and swarm optimisation techniques (SOTs). For this purpose, the design problem is formulated as mean square error between the actual response and ideal response in frequency domain using polyphase components of a prototype filter. To achieve more precise frequency response at some specified frequency, fractional derivative constraints (FDCs) have been applied, and optimal FDCs are computed using SOTs such as cuckoo search and modified cuckoo search algorithms. A comparative study of well-proved swarm optimisation, called particle swarm optimisation and artificial bee colony algorithm is made. The excellence of proposed method is evaluated using several important attributes of a filter. Comparative study evidences the excellence of proposed method for effective design of FIR filter.

Design and implementation of a multiband digital filter using FPGA to extract the ECG signal in the presence of different interference signals.

PubMed

Aboutabikh, Kamal; Aboukerdah, Nader

2015-07-01

In this paper, we propose a practical way to synthesize and filter an ECG signal in the presence of four types of interference signals: (1) those arising from power networks with a fundamental frequency of 50Hz, (2) those arising from respiration, having a frequency range from 0.05 to 0.5Hz, (3) muscle signals with a frequency of 25Hz, and (4) white noise present within the ECG signal band. This was done by implementing a multiband digital filter (seven bands) of type FIR Multiband Least Squares using a digital programmable device (Cyclone II EP2C70F896C6 FPGA, Altera), which was placed on an education and development board (DE2-70, Terasic). This filter was designed using the VHDL language in the Quartus II 9.1 design environment. The proposed method depends on Direct Digital Frequency Synthesizers (DDFS) designed to synthesize the ECG signal and various interference signals. So that the synthetic ECG specifications would be closer to actual ECG signals after filtering, we designed in a single multiband digital filter instead of using three separate digital filters LPF, HPF, BSF. Thus all interference signals were removed with a single digital filter. The multiband digital filter results were studied using a digital oscilloscope to characterize input and output signals in the presence of differing sinusoidal interference signals and white noise. Copyright © 2015 Elsevier Ltd. All rights reserved.

UWB Bandpass Filter with Ultra-wide Stopband based on Ring Resonator

NASA Astrophysics Data System (ADS)

Kazemi, Maryam; Lotfi, Saeedeh; Siahkamari, Hesam; Mohammadpanah, Mahmood

2018-04-01

An ultra-wideband (UWB) bandpass filter with ultra-wide stopband based on a rectangular ring resonator is presented. The filter is designed for the operational frequency band from 4.10 GHz to 10.80 GHz with an ultra-wide stopband from 11.23 GHz to 40 GHz. The even and odd equivalent circuits are used to achieve a suitable analysis of the proposed filter performance. To verify the design and analysis, the proposed bandpass filter is simulated using full-wave EM simulator Advanced Design System and fabricated on a 20mil thick Rogers_RO4003 substrate with relative permittivity of 3.38 and a loss tangent of 0.0021. The proposed filter behavior is investigated and simulation results are in good agreement with measurement results.

A New Scheme for the Design of Hilbert Transform Pairs of Biorthogonal Wavelet Bases

NASA Astrophysics Data System (ADS)

Shi, Hongli; Luo, Shuqian

2010-12-01

In designing the Hilbert transform pairs of biorthogonal wavelet bases, it has been shown that the requirements of the equal-magnitude responses and the half-sample phase offset on the lowpass filters are the necessary and sufficient condition. In this paper, the relationship between the phase offset and the vanishing moment difference of biorthogonal scaling filters is derived, which implies a simple way to choose the vanishing moments so that the phase response requirement can be satisfied structurally. The magnitude response requirement is approximately achieved by a constrained optimization procedure, where the objective function and constraints are all expressed in terms of the auxiliary filters of scaling filters rather than the scaling filters directly. Generally, the calculation burden in the design implementation will be less than that of the current schemes. The integral of magnitude response difference between the primal and dual scaling filters has been chosen as the objective function, which expresses the magnitude response requirements in the whole frequency range. Two design examples illustrate that the biorthogonal wavelet bases designed by the proposed scheme are very close to Hilbert transform pairs.

Role of the Filters in the Formation and Stabilization of Semiquinone Radicals Collected from Cigarette Smoke

PubMed Central

Maskos, Zofia; Dellinger, Barry

2013-01-01

The fractional pyrolysis of Bright tobacco was performed in nitrogen atmosphere over the temperature range of 240 – 510 °C in a specially constructed, high temperature flow reactor system. Electron paramagnetic resonance (EPR) spectroscopy was used to analyze the free radicals in the initially produced total particular matter (TPM) and in TPM after exposure to ambient air (aging). Different filters have been used to collect TPM from tobacco smoke: cellulosic, cellulose nitrate, cellulose acetate, nylon, Teflon and Cambridge. The collection of the primary radicals (measured immediately after collection of TPM on filters), the formation and stabilization of the secondary radicals (defined as radicals formed during aging of TPM samples on the filters) depend significantly on the material of the filter. A mechanistic explanation about different binding capability of the filters decreasing in the order: cellulosic < cellulose nitrate < cellulose acetate < nylon ~ teflon is presented. Different properties were observed for the Cambridge filter. Specific care must be taken using the filters for identification of radicals from tobacco smoke to avoid artifacts in each case. PMID:24265513

Systematic Biological Filter Design with a Desired I/O Filtering Response Based on Promoter-RBS Libraries.

PubMed

Hsu, Chih-Yuan; Pan, Zhen-Ming; Hu, Rei-Hsing; Chang, Chih-Chun; Cheng, Hsiao-Chun; Lin, Che; Chen, Bor-Sen

2015-01-01

In this study, robust biological filters with an external control to match a desired input/output (I/O) filtering response are engineered based on the well-characterized promoter-RBS libraries and a cascade gene circuit topology. In the field of synthetic biology, the biological filter system serves as a powerful detector or sensor to sense different molecular signals and produces a specific output response only if the concentration of the input molecular signal is higher or lower than a specified threshold. The proposed systematic design method of robust biological filters is summarized into three steps. Firstly, several well-characterized promoter-RBS libraries are established for biological filter design by identifying and collecting the quantitative and qualitative characteristics of their promoter-RBS components via nonlinear parameter estimation method. Then, the topology of synthetic biological filter is decomposed into three cascade gene regulatory modules, and an appropriate promoter-RBS library is selected for each module to achieve the desired I/O specification of a biological filter. Finally, based on the proposed systematic method, a robust externally tunable biological filter is engineered by searching the promoter-RBS component libraries and a control inducer concentration library to achieve the optimal reference match for the specified I/O filtering response.

Chirped-cavity dispersion-compensation filter design.

PubMed

Li, Ya-Ping; Chen, Sheng-Hui; Lee, Cheng-Chung

2006-03-01

A new basic structure of a dispersive-compensation filter, called a chirped-cavity dispersion-compensator (CCDC) filter, was designed to offer the advantages of small ripples in both reflectance and group-delay dispersion (GDD). This filter provides a high dispersion compensation, like the Gires-Tournois interferometer (GTI) filter, and a wide working bandwidth, like the chirped mirror (CM). The structure of the CCDC is a cavity-type Fabry-Perot filter with a spacer layer (2 mH or 2 mL) and a chirped high reflector. The CCDC filter can provide a negative GDD of -50 fs2 over a bandwidth of 56 THz with half the optical thickness of the CM or the GTI.

Chirped-cavity dispersion-compensation filter design

NASA Astrophysics Data System (ADS)

Li, Ya-Ping; Chen, Sheng-Hui; Lee, Cheng-Chung

2006-03-01

A new basic structure of a dispersive-compensation filter, called a chirped-cavity dispersion-compensator (CCDC) filter, was designed to offer the advantages of small ripples in both reflectance and group-delay dispersion (GDD). This filter provides a high dispersion compensation, like the Gires-Tournois interferometer (GTI) filter, and a wide working bandwidth, like the chirped mirror (CM). The structure of the CCDC is a cavity-type Fabry-Perot filter with a spacer layer (2 mH or 2 mL) and a chirped high reflector. The CCDC filter can provide a negative GDD of -50 fs2 over a bandwidth of 56 THz with half the optical thickness of the CM or the GTI.

Bimanual tapping of a syncopated rhythm reveals hemispheric preferences for relative movement frequencies.

PubMed

Pflug, Anja; Gompf, Florian; Kell, Christian Alexander

2017-08-01

In bimanual multifrequency tapping, right-handers commonly use the right hand to tap the relatively higher rate and the left hand to tap the relatively lower rate. This could be due to hemispheric specializations for the processing of relative frequencies. An extension of the double-filtering-by-frequency theory to motor control proposes a left hemispheric specialization for the control of relatively high and a right hemispheric specialization for the control of relatively low tapping rates. We investigated timing variability and rhythmic accentuation in right handers tapping mono- and multifrequent bimanual rhythms to test the predictions of the double-filtering-by-frequency theory. Yet, hemispheric specializations for the processing of relative tapping rates could be masked by a left hemispheric dominance for the control of known sequences. Tapping was thus either performed in an overlearned quadruple meter (tap of the slow rhythm on the first auditory beat) or in a syncopated quadruple meter (tap of the slow rhythm on the fourth auditory beat). Independent of syncopation, the right hand outperformed the left hand in timing accuracy for fast tapping. A left hand timing benefit for slow tapping rates as predicted by the double-filtering-by-frequency theory was only found in the syncopated tapping group. This suggests a right hemisphere preference for the control of slow tapping rates when rhythms are not overlearned. Error rates indicate that overlearned rhythms represent hierarchically structured meters that are controlled by a single timer that could potentially reside in the left hemisphere. Copyright © 2017 Elsevier B.V. All rights reserved.

Orthonormal filters for identification in active control systems

NASA Astrophysics Data System (ADS)

Mayer, Dirk

2015-12-01

Many active noise and vibration control systems require models of the control paths. When the controlled system changes slightly over time, adaptive digital filters for the identification of the models are useful. This paper aims at the investigation of a special class of adaptive digital filters: orthonormal filter banks possess the robust and simple adaptation of the widely applied finite impulse response (FIR) filters, but at a lower model order, which is important when considering implementation on embedded systems. However, the filter banks require prior knowledge about the resonance frequencies and damping of the structure. This knowledge can be supposed to be of limited precision, since in many practical systems, uncertainties in the structural parameters exist. In this work, a procedure using a number of training systems to find the fixed parameters for the filter banks is applied. The effect of uncertainties in the prior knowledge on the model error is examined both with a basic example and in an experiment. Furthermore, the possibilities to compensate for the imprecise prior knowledge by a higher filter order are investigated. Also comparisons with FIR filters are implemented in order to assess the possible advantages of the orthonormal filter banks. Numerical and experimental investigations show that significantly lower computational effort can be reached by the filter banks under certain conditions.

Designer Infrared Filters using Stacked Metal Lattices

NASA Technical Reports Server (NTRS)

Smith, Howard A.; Rebbert, M.; Sternberg, O.

2003-01-01

We have designed and fabricated infrared filters for use at wavelengths greater than or equal to 15 microns. Unlike conventional dielectric filters used at the short wavelengths, ours are made from stacked metal grids, spaced at a very small fraction of the performance wavelengths. The individual lattice layers are gold, the spacers are polyimide, and they are assembled using integrated circuit processing techniques; they resemble some metallic photonic band-gap structures. We simulate the filter performance accurately, including the coupling of the propagating, near-field electromagnetic modes, using computer aided design codes. We find no anomalous absorption. The geometrical parameters of the grids are easily altered in practice, allowing for the production of tuned filters with predictable useful transmission characteristics. Although developed for astronomical instrumentation, the filters arc broadly applicable in systems across infrared and terahertz bands.

The Analysis of the System of special water purification of Beloyarskaya Nuclear Power Plant unit BN-800

NASA Astrophysics Data System (ADS)

Valtseva, A. I.; Bibik, I. S.

2017-11-01

This article discusses how the latest system of special water purification KPF-30, designed specifically for the fourth power unit of Beloyarskaya nuclear power plant, which has a number of advantages over other water purification systems as chemical-physical and technical-economic, environmental, and other industrial indicators. The scheme covered in this article systems of special water purification involves the use of a hydrocyclone at the preliminary stage of water treatment, as a worthy alternative to ion-exchange filters, which can significantly reduce the volume of toxic waste. The world community implements the project of closing the nuclear fuel cycle, there is a need to improve the reliability of the equipment for safe processes and development of critical and supercritical parameters in the nuclear industry. Essentially, on operated NPP units, the only factor that can cost-effectively optimize to improve the reliability of equipment is the water chemistry. System KPF30 meets the principles and criteria of ecological safety, demonstrating the justification for reagent less method of water treatment on the main stages, in which no formation of toxic wastes, leading to irreversible consequences of environmental pollution and helps to conserve water.

Nitinol Embolic Protection Filters: Design Investigation by Finite Element Analysis

NASA Astrophysics Data System (ADS)

Conti, Michele; de Beule, Matthieu; Mortier, Peter; van Loo, Denis; Verdonck, Pascal; Vermassen, Frank; Segers, Patrick; Auricchio, Ferdinando; Verhegghe, Benedict

2009-08-01

The widespread acceptance of carotid artery stenting (CAS) to treat carotid artery stenosis and its effectiveness compared with surgical counterpart, carotid endarterectomy (CEA), is still a matter of debate. Transient or permanent neurological deficits may develop in patients undergoing CAS due to distal embolization or hemodynamic changes. Design, development, and usage of embolic protection devices (EPDs), such as embolic protection filters, appear to have a significant impact on the success of CAS. Unfortunately, some drawbacks, such as filtering failure, inability to cross tortuous high-grade stenoses, malpositioning and vessel injury, still remain and require design improvement. Currently, many different designs of such devices are available on the rapidly growing dedicated market. In spite of such a growing commercial interest, there is a significant need for design tools as well as for careful engineering investigations and design analyses of such nitinol devices. The present study aims to investigate the embolic protection filter design by finite element analysis. We first developed a parametrical computer-aided design model of an embolic filter based on micro-CT scans of the Angioguard™ XP (Cordis Endovascular, FL) EPD by means of the open source pyFormex software. Subsequently, we used the finite element method to simulate the deployment of the nitinol filter as it exits the delivery sheath. Comparison of the simulations with micro-CT images of the real device exiting the catheter showed excellent correspondence with our simulations. Finally, we evaluated circumferential basket-vessel wall apposition of a 4 mm size filter in a straight vessel of different sizes and shape. We conclude that the proposed methodology offers a useful tool to evaluate and to compare current or new designs of EPDs. Further simulations will investigate vessel wall apposition in a realistic tortuous anatomy.

Radar range data signal enhancement tracker

NASA Technical Reports Server (NTRS)

1975-01-01

The design, fabrication, and performance characteristics are described of two digital data signal enhancement filters which are capable of being inserted between the Space Shuttle Navigation Sensor outputs and the guidance computer. Commonality of interfaces has been stressed so that the filters may be evaluated through operation with simulated sensors or with actual prototype sensor hardware. The filters will provide both a smoothed range and range rate output. Different conceptual approaches are utilized for each filter. The first filter is based on a combination low pass nonrecursive filter and a cascaded simple average smoother for range and range rate, respectively. Filter number two is a tracking filter which is capable of following transient data of the type encountered during burn periods. A test simulator was also designed which generates typical shuttle navigation sensor data.

Tunable plasmon-induced transparency effect based on self-asymmetric H-shaped resonators meta-atoms

NASA Astrophysics Data System (ADS)

Cheng, Zhaoxiang; Chen, Lin; Zang, Xiaofei; Cai, Bin; Peng, Yan; Zhu, Yiming

2015-03-01

We have proposed and demonstrated a tunable plasmon-induced transparency (PIT) effect from two ways, based on self-asymmetric H-shaped resonators (AHR) meta-atoms. The tunable PIT effect is realized via varying polarization angles and coupling distances. First, by proper design, transition from PIT mode to dipole mode is theoretically and experimentally demonstrated by simply adjusting the polarization angle. Also, the manipulation of ‘dark-mode’ resonance intensity from strong to weak is achieved by varying coupling strength with different distances, which provided insight into the magnetic coupling hybridization mechanism. Prospectively, due to its special tunable characteristics, the AHR meta-atoms may be widely used in slow light, filters and switch devices.

Separable concatenated codes with iterative map decoding for Rician fading channels

NASA Technical Reports Server (NTRS)

Lodge, J. H.; Young, R. J.

1993-01-01

Very efficient signalling in radio channels requires the design of very powerful codes having special structure suitable for practical decoding schemes. In this paper, powerful codes are obtained by combining comparatively simple convolutional codes to form multi-tiered 'separable' convolutional codes. The decoding of these codes, using separable symbol-by-symbol maximum a posteriori (MAP) 'filters', is described. It is known that this approach yields impressive results in non-fading additive white Gaussian noise channels. Interleaving is an inherent part of the code construction, and consequently, these codes are well suited for fading channel communications. Here, simulation results for communications over Rician fading channels are presented to support this claim.

Design of thin-film filters for resolution improvements in filter-array based spectrometers using DSP

NASA Astrophysics Data System (ADS)

Lee, Woong-Bi; Kim, Cheolsun; Ju, Gun Wu; Lee, Yong Tak; Lee, Heung-No

2016-05-01

Miniature spectrometers have been widely developed in various academic and industrial applications such as bio-medical, chemical and environmental engineering. As a family of spectrometers, optical filter-array based spectrometers fabricated using CMOS or Nano technology provide miniaturization, superior portability and cost effectiveness. In filterarray based spectrometers, the resolution which represents the ability how closely resolve two neighboring spectra, depends on the number of filters and the characteristics of the transmission functions (TFs) of the filters. In practice, due to the small-size and low-cost fabrication, the number of filters is limited and the shape of the TF of each filter is nonideal. As a development of modern digital signal processing (DSP), the spectrometers are equipped with DSP algorithms not only to alleviate distortions due to unexpected noise or interferences among filters but also reconstruct the original signal spectrum. For a high-resolution spectrum reconstruction by the DSP, the TFs of the filters need to be sufficiently uncorrelated with each other. In this paper, we present a design of optical thin-film filters which have the uncorrelated TFs. Each filter consists of multiple layers of high- and low-refractive index materials deposited on a substrate. The proposed design helps the DSP algorithm to improve resolution with a small number of filters. We demonstrate that a resolution of 5 nm within a range from 500 nm to 1100 nm can be achieved with only 64 filters.

An improved cosmic crystallography method to detect holonomies in flat spaces

NASA Astrophysics Data System (ADS)

Fujii, H.; Yoshii, Y.

2011-05-01

A new, improved version of a cosmic crystallography method for constraining cosmic topology is introduced. Like the circles-in-the-sky method using CMB data, we work in a thin, shell-like region containing plenty of objects. Two pairs of objects (quadruplet) linked by a holonomy show a specific distribution pattern, and three filters of separation, vectorial condition, and lifetime of objects extract these quadruplets. Each object Pi is assigned an integer si, which is the number of candidate quadruplets including Pi as their members. Then an additional device of si-histogram is used to extract topological ghosts, which tend to have high values of si. In this paper we consider flat spaces with Euclidean geometry, and the filters are designed to constrain their holonomies. As the second filter, we prepared five types that are specialized for constraining specific holonomies: one for translation, one for half-turn corkscrew motion and glide reflection, and three for nth turn corkscrew motion for n = 4,3, and 6. Every multiconnected space has holonomies that are detected by at least one of these five filters.Our method is applied to the catalogs of toy quasars in flat Λ-CDM universes whose typical sizes correspond to z ~ 5. With these simulations our method is found to work quite well. These are the situations in which type-II pair crystallography methods are insensitive because of the tiny number of ghosts. Moreover, in the flat cases, our method should be more sensitive than the type-I pair (or, in general, n-tuplet) methods because of its multifilter construction and its independence from n.

Multi-Sensor Fusion with Interaction Multiple Model and Chi-Square Test Tolerant Filter.

PubMed

Yang, Chun; Mohammadi, Arash; Chen, Qing-Wei

2016-11-02

Motivated by the key importance of multi-sensor information fusion algorithms in the state-of-the-art integrated navigation systems due to recent advancements in sensor technologies, telecommunication, and navigation systems, the paper proposes an improved and innovative fault-tolerant fusion framework. An integrated navigation system is considered consisting of four sensory sub-systems, i.e., Strap-down Inertial Navigation System (SINS), Global Navigation System (GPS), the Bei-Dou2 (BD2) and Celestial Navigation System (CNS) navigation sensors. In such multi-sensor applications, on the one hand, the design of an efficient fusion methodology is extremely constrained specially when no information regarding the system's error characteristics is available. On the other hand, the development of an accurate fault detection and integrity monitoring solution is both challenging and critical. The paper addresses the sensitivity issues of conventional fault detection solutions and the unavailability of a precisely known system model by jointly designing fault detection and information fusion algorithms. In particular, by using ideas from Interacting Multiple Model (IMM) filters, the uncertainty of the system will be adjusted adaptively by model probabilities and using the proposed fuzzy-based fusion framework. The paper also addresses the problem of using corrupted measurements for fault detection purposes by designing a two state propagator chi-square test jointly with the fusion algorithm. Two IMM predictors, running in parallel, are used and alternatively reactivated based on the received information form the fusion filter to increase the reliability and accuracy of the proposed detection solution. With the combination of the IMM and the proposed fusion method, we increase the failure sensitivity of the detection system and, thereby, significantly increase the overall reliability and accuracy of the integrated navigation system. Simulation results indicate that the proposed fault tolerant fusion framework provides superior performance over its traditional counterparts.

Multi-Sensor Fusion with Interaction Multiple Model and Chi-Square Test Tolerant Filter

PubMed Central

Yang, Chun; Mohammadi, Arash; Chen, Qing-Wei

2016-01-01

Motivated by the key importance of multi-sensor information fusion algorithms in the state-of-the-art integrated navigation systems due to recent advancements in sensor technologies, telecommunication, and navigation systems, the paper proposes an improved and innovative fault-tolerant fusion framework. An integrated navigation system is considered consisting of four sensory sub-systems, i.e., Strap-down Inertial Navigation System (SINS), Global Navigation System (GPS), the Bei-Dou2 (BD2) and Celestial Navigation System (CNS) navigation sensors. In such multi-sensor applications, on the one hand, the design of an efficient fusion methodology is extremely constrained specially when no information regarding the system’s error characteristics is available. On the other hand, the development of an accurate fault detection and integrity monitoring solution is both challenging and critical. The paper addresses the sensitivity issues of conventional fault detection solutions and the unavailability of a precisely known system model by jointly designing fault detection and information fusion algorithms. In particular, by using ideas from Interacting Multiple Model (IMM) filters, the uncertainty of the system will be adjusted adaptively by model probabilities and using the proposed fuzzy-based fusion framework. The paper also addresses the problem of using corrupted measurements for fault detection purposes by designing a two state propagator chi-square test jointly with the fusion algorithm. Two IMM predictors, running in parallel, are used and alternatively reactivated based on the received information form the fusion filter to increase the reliability and accuracy of the proposed detection solution. With the combination of the IMM and the proposed fusion method, we increase the failure sensitivity of the detection system and, thereby, significantly increase the overall reliability and accuracy of the integrated navigation system. Simulation results indicate that the proposed fault tolerant fusion framework provides superior performance over its traditional counterparts. PMID:27827832

Wideband dichroic-filter design for LED-phosphor beam-combining

DOEpatents

Falicoff, Waqidi

2010-12-28

A general method is disclosed of designing two-component dichroic short-pass filters operable for incidence angle distributions over the 0-30.degree. range, and specific preferred embodiments are listed. The method is based on computer optimization algorithms for an N-layer design, specifically the N-dimensional conjugate-gradient minimization of a merit function based on difference from a target transmission spectrum, as well as subsequent cycles of needle synthesis for increasing N. A key feature of the method is the initial filter design, upon which the algorithm proceeds to iterate successive design candidates with smaller merit functions. This initial design, with high-index material H and low-index L, is (0.75 H, 0.5 L, 0.75 H)^m, denoting m (20-30) repetitions of a three-layer motif, giving rise to a filter with N=2 m+1.

Distributed digital signal processors for multi-body structures

NASA Technical Reports Server (NTRS)

Lee, Gordon K.

1990-01-01

Several digital filter designs were investigated which may be used to process sensor data from large space structures and to design digital hardware to implement the distributed signal processing architecture. Several experimental tests articles are available at NASA Langley Research Center to evaluate these designs. A summary of some of the digital filter designs is presented, an evaluation of their characteristics relative to control design is discussed, and candidate hardware microcontroller/microcomputer components are given. Future activities include software evaluation of the digital filter designs and actual hardware inplementation of some of the signal processor algorithms on an experimental testbed at NASA Langley.

Water system virus detection

NASA Technical Reports Server (NTRS)

Fraser, A. S.; Wells, A. F.; Tenoso, H. J.

1975-01-01

A monitoring system developed to test the capability of a water recovery system to reject the passage of viruses into the recovered water is described. A nonpathogenic marker virus, bacteriophage F2, is fed into the process stream before the recovery unit and the reclaimed water is assayed for its presence. Detection of the marker virus consists of two major components, concentration and isolation of the marker virus, and detection of the marker virus. The concentration system involves adsorption of virus to cellulose acetate filters in the presence of trivalent cations and low pH with subsequent desorption of the virus using volumes of high pH buffer. The detection of the virus is performed by a passive immune agglutination test utilizing specially prepared polystyrene particles. An engineering preliminary design was performed as a parallel effort to the laboratory development of the marker virus test system. Engineering schematics and drawings of a fully functional laboratory prototype capable of zero-G operation are presented. The instrument consists of reagent pump/metering system, reagent storage containers, a filter concentrator, an incubation/detector system, and an electronic readout and control system.

Symmetric/Asymmetrical SIRs Dual-Band BPF Design for WLAN Applications

NASA Astrophysics Data System (ADS)

Ho, Min-Hua; Ho, Hao-Hung; Chen, Mingchih

This paper presents the dual-band bandpass filters (BPFs) design composed of λ/2 and symmetrically/asymmetrically paired λ/4 stepped impedance resonators (SIRs) for the WLAN applications. The filters cover both the operating frequencies of 2.45 and 5.2GHz. The dual-coupling mechanism is used in the filter design to provide alternative routes for signals of selected frequencies. A prototype filter is composed of λ/2 and symmetrical λ/4 SIRs. The enhanced wide-stopband filter is then developed from the filter with the symmetrical λ/4 SIRs replaced by the asymmetrical ones. The asymmetrical λ/4 SIRs have their higher resonances frequencies isolated from the adjacent I/O SIRs and extend the enhanced filter an upper stopband limit beyond ten time the fundamental frequency. Also, the filter might possess a cross-coupling structure which introduces transmission zeros by the passband edges to improve the signal selectivity. The tapped-line feed is adopted in this circuit to create additional attenuation poles for improving the stopband rejection levels. Experiments are conducted to verify the circuit performance.

Impedance Matched Absorptive Thermal Blocking Filters

NASA Technical Reports Server (NTRS)

Wollack, E. J.; Chuss, D. T.; U-Yen, K.; Rostem, K.

2014-01-01

We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50 Omega and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

Impedance Matched Absorptive Thermal Blocking Filters

NASA Technical Reports Server (NTRS)

Wollack, E. J.; Chuss, D. T.; Rostem, K.; U-Yen, K.

2014-01-01

We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50O and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

Iterative design of one- and two-dimensional FIR digital filters. [Finite duration Impulse Response

NASA Technical Reports Server (NTRS)

Suk, M.; Choi, K.; Algazi, V. R.

1976-01-01

The paper describes a new iterative technique for designing FIR (finite duration impulse response) digital filters using a frequency weighted least squares approximation. The technique is as easy to implement (via FFT) and as effective in two dimensions as in one dimension, and there are virtually no limitations on the class of filter frequency spectra approximated. An adaptive adjustment of the frequency weight to achieve other types of design approximation such as Chebyshev type design is discussed.

Input filter compensation for switching regulators

NASA Technical Reports Server (NTRS)

Kelkar, S. S.; Lee, F. C.

1983-01-01

A novel input filter compensation scheme for a buck regulator that eliminates the interaction between the input filter output impedance and the regulator control loop is presented. The scheme is implemented using a feedforward loop that senses the input filter state variables and uses this information to modulate the duty cycle signal. The feedforward design process presented is seen to be straightforward and the feedforward easy to implement. Extensive experimental data supported by analytical results show that significant performance improvement is achieved with the use of feedforward in the following performance categories: loop stability, audiosusceptibility, output impedance and transient response. The use of feedforward results in isolating the switching regulator from its power source thus eliminating all interaction between the regulator and equipment upstream. In addition the use of feedforward removes some of the input filter design constraints and makes the input filter design process simpler thus making it possible to optimize the input filter. The concept of feedforward compensation can also be extended to other types of switching regulators.

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.

Optical Fourier filtering for whole lens assessment of progressive power lenses.

PubMed

Spiers, T; Hull, C C

2000-07-01

Four binary filter designs for use in an optical Fourier filtering set-up were evaluated when taking quantitative measurements and when qualitatively mapping the power variation of progressive power lenses (PPLs). The binary filters tested were concentric ring, linear grating, grid and "chevron" designs. The chevron filter was considered best for quantitative measurements since it permitted a vernier acuity task to be used for measuring the fringe spacing, significantly reducing errors, and it also gave information on the polarity of the lens power. The linear grating filter was considered best for qualitatively evaluating the power variation. Optical Fourier filtering and a Nidek automatic focimeter were then used to measure the powers in the distance and near portions of five PPLs of differing design. Mean measurement error was 0.04 D with a maximum value of 0.13 D. Good qualitative agreement was found between the iso-cylinder plots provided by the manufacturer and the Fourier filter fringe patterns for the PPLs indicating that optical Fourier filtering provides the ability to map the power distribution across the entire lens aperture without the need for multiple point measurements. Arguments are presented that demonstrate that it should be possible to derive both iso-sphere and iso-cylinder plots from the binary filter patterns.

Low-loss interference filter arrays made by plasma-assisted reactive magnetron sputtering (PARMS) for high-performance multispectral imaging

NASA Astrophysics Data System (ADS)

Broßmann, Jan; Best, Thorsten; Bauer, Thomas; Jakobs, Stefan; Eisenhammer, Thomas

2016-10-01

Optical remote sensing of the earth from air and space typically utilizes several channels in the visible and near infrared spectrum. Thin-film optical interference filters, mostly of narrow bandpass type, are applied to select these channels. The filters are arranged in filter wheels, arrays of discrete stripe filters mounted in frames, or patterned arrays on a monolithic substrate. Such multi-channel filter assemblies can be mounted close to the detector, which allows a compact and lightweight camera design. Recent progress in image resolution and sensor sensitivity requires improvements of the optical filter performance. Higher demands placed on blocking in the UV and NIR and in between the spectral channels, in-band transmission and filter edge steepness as well as scattering lead to more complex filter coatings with thicknesses in the range of 10 - 25μm. Technological limits of the conventionally used ion-assisted evaporation process (IAD) can be overcome only by more precise and higher-energetic coating technologies like plasma-assisted reactive magnetron sputtering (PARMS) in combination with optical broadband monitoring. Optics Balzers has developed a photolithographic patterning process for coating thicknesses up to 15μm that is fully compatible with the advanced PARMS coating technology. This provides the possibility of depositing multiple complex high-performance filters on a monolithic substrate. We present an overview of the performance of recently developed filters with improved spectral performance designed for both monolithic filter-arrays and stripe filters mounted in frames. The pros and cons as well as the resulting limits of the filter designs for both configurations are discussed.

A robust approach to optimal matched filter design in ultrasonic non-destructive evaluation (NDE)

NASA Astrophysics Data System (ADS)

Li, Minghui; Hayward, Gordon

2017-02-01

The matched filter was demonstrated to be a powerful yet efficient technique to enhance defect detection and imaging in ultrasonic non-destructive evaluation (NDE) of coarse grain materials, provided that the filter was properly designed and optimized. In the literature, in order to accurately approximate the defect echoes, the design utilized the real excitation signals, which made it time consuming and less straightforward to implement in practice. In this paper, we present a more robust and flexible approach to optimal matched filter design using the simulated excitation signals, and the control parameters are chosen and optimized based on the real scenario of array transducer, transmitter-receiver system response, and the test sample, as a result, the filter response is optimized and depends on the material characteristics. Experiments on industrial samples are conducted and the results confirm the great benefits of the method.

Special-purpose fiber type 475--toxicological assessment.

PubMed

Bernstein, D M

2007-02-01

Type 475 special-purpose glass fiber is rather unique among the family of synthetic mineral fibers. It is used not for insulation but for "high-end" filtration products designed for high and ultra-high purity filtration of air and liquids. The designation for these types of filters varies with country and includes HEPA, ULPA, EU 10-13, EN1822, and S3. In its evaluation, type 475 has been grouped together with E-glass another special-purpose fibre often with little distinction made in terms of its chemistry and corresponding toxicological response. The detailed review of the available toxicology data on type 475 glass fibers clearly shows that following inhalation of this fiber even at relatively high doses, which likely exceed that at which lung overload in the rat is known to occur, type 475 glass fibers are not fibrogenic and do not cause tumors. These data clearly show an important differentiation in potency between type 475 glass fibers and E-glass and support treating these two types of fibers independently and not equating them though the term "special-purpose fibers." Analysis of the intraperitoneal studies taking into account fibre dimensions shows that at 109 fibers injected, there was a 0.3 tumor incidence. While these studies indicate according to the European Commission (EC) classification criteria that 475 should not be fully exonerated as a carcinogen, the results of the inhalation study fully support classification in category 3. The IP results are more difficult to interpret, however, the IP study itself provides no toxicological basis for determining what range of dose-response should correspond to EU category 3 or 2. Following the EC classification criteria, the toxicological data clearly indicate that 475 fibers are appropriately classified in EC category 3.

Phase Response Design of Recursive All-Pass Digital Filters Using a Modified PSO Algorithm

PubMed Central

2015-01-01

This paper develops a new design scheme for the phase response of an all-pass recursive digital filter. A variant of particle swarm optimization (PSO) algorithm will be utilized for solving this kind of filter design problem. It is here called the modified PSO (MPSO) algorithm in which another adjusting factor is more introduced in the velocity updating formula of the algorithm in order to improve the searching ability. In the proposed method, all of the designed filter coefficients are firstly collected to be a parameter vector and this vector is regarded as a particle of the algorithm. The MPSO with a modified velocity formula will force all particles into moving toward the optimal or near optimal solution by minimizing some defined objective function of the optimization problem. To show the effectiveness of the proposed method, two different kinds of linear phase response design examples are illustrated and the general PSO algorithm is compared as well. The obtained results show that the MPSO is superior to the general PSO for the phase response design of digital recursive all-pass filter. PMID:26366168

An improved ultra-wideband bandpass filter design using split ring resonator with coupled microstrip line

NASA Astrophysics Data System (ADS)

Umeshkumar, Dubey Suhmita; Kumar, Manish

2018-04-01

This paper incorporates an improved design of Ultra Wideband Bandpass filter by using split ring resonators (SRR) along with the coupled microstrip lines. The use of split ring resonators and shunt step impedance open circuit stub enhances the stability due to transmission zeroes at the ends. The designing of filter and simulation of parameters is carried out using Ansoft's HFSS 13.0 software on RT/Duroid 6002 as a substrate with dielectric constant of 2.94. The design utilizes a frequency band from 22GHz to 29GHz. This band is reserved for Automotive Radar system and sensors as per FCC specifications. The proposed design demonstrates insertion loss less than 0.6dB and return loss better than 12dB at mid frequency i.e. 24.4GHz. The reflection coefficient shows high stability of about 12.47dB at mid frequency. The fractional bandwidth of the proposed filter is about 28.7% and size of filter design is small due to thickness of 0.127mm.

Design optimisation of powers-of-two FIR filter using self-organising random immigrants GA

NASA Astrophysics Data System (ADS)

Chandra, Abhijit; Chattopadhyay, Sudipta

2015-01-01

In this communication, we propose a novel design strategy of multiplier-less low-pass finite impulse response (FIR) filter with the aid of a recent evolutionary optimisation technique, known as the self-organising random immigrants genetic algorithm. Individual impulse response coefficients of the proposed filter have been encoded as sum of signed powers-of-two. During the formulation of the cost function for the optimisation algorithm, both the frequency response characteristic and the hardware cost of the discrete coefficient FIR filter have been considered. The role of crossover probability of the optimisation technique has been evaluated on the overall performance of the proposed strategy. For this purpose, the convergence characteristic of the optimisation technique has been included in the simulation results. In our analysis, two design examples of different specifications have been taken into account. In order to substantiate the efficiency of our proposed structure, a number of state-of-the-art design strategies of multiplier-less FIR filter have also been included in this article for the purpose of comparison. Critical analysis of the result unambiguously establishes the usefulness of our proposed approach for the hardware efficient design of digital filter.

In Vitro Evaluation of a Rheolytic Thrombectomy System for Clot Removal from Five Different Temporary Vena Cava Filters

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

Buecker, Arno; Neuerburg, Joerg; Schmitz-Rode, Thomas

1997-11-15

Purpose: To evaluate the feasibility of thrombus removal from temporary vena cava filters using a rheolytic thrombectomy device and to assess the embolization rate of this procedure. Methods: Five temporary vena cava filters together with porcine thrombi were placed in a vena cava flow model (semitranslucent silicone tube of 23 mm diameter, pulsatile flow at a mean flow rate of 4 L/min). A rheolytic thrombectomy system (Hydrolyser) was used with a 9 Fr guiding catheter to remove the clots. The effluent was passed through filters of different size and the amount of embolized particles as well as the remaining thrombusmore » were measured. Results: Thrombus removal rates ranged from 85% to 100%. Embolization rates between 47% and 60% were calculated for the different filters. Conclusion: The Hydrolyser is able to remove sufficiently high amounts of thrombus from temporary vena cava filters. However, the amount of embolized particles makes it impossible to utilize this method without special precautions against embolization.« less

Fibrous Filter to Protect Building Environments from Polluting Agents: A Review

NASA Astrophysics Data System (ADS)

Chavhan, Md. Vaseem; Mukhopadhyay, Arunangshu

2016-04-01

This paper discusses the use of fibrous filter to protect the building environments from air born polluting agents and especially of concern chemical, biological and radiological agents. Air-filtration includes removal of particulate from air and toxic gases from air. In air filtration, particulate which are mostly biological and radioactive types of agents can be removed by using mechanical and electrostatic filters. Some biological agents, which cannot be removed by air filtration alone, special techniques like antimicrobial finish, UV germicides, coated filters etc. are required. Biocide agent can be added into the fibre itself by grafting reaction to impart antimicrobial activity. Chemical agents like toxic gases can be removed by integrating adsorbents and sorbents in filters or by fibre modifications. It is also possible to impart catalytic conversion properties into the fibre to remove volatile gasous. Radioactive agents can be removed by particulate filter if present in the form of aerosol or by gas cleaning by the use of specific fibre impregnate.

Cryptosporidium: A Guide to Water Filters

MedlinePlus

... label> Parasites Home A Guide to Water Filters Recommend on Facebook Tweet Share Compartir Filtering Tap ... absolute pore size of 1 micron or smaller. Filters designed to remove Crypto (any of the four ...

Flow Separation

DTIC Science & Technology

1975-11-01

PLENUM CHAMBER 4 DIFFUSER 2 FIXEn NOZZLE BLOCK 5 MODEL i MOVABLE NOZZLE BLOCK 6 SUPPORT Fig. 3. Trl-Color Filter ...boun- dary layer ( Model 2) to examine scaling effects. Special attention was paid to the phenomenon of flow separation in three dimensions...consequence. Special attention should be paid to the difference in scale of an average boundary layer thickness between Model 1 and 2. Because

Design, construction and operation of a new filter approach for treatment of surface waters in Southeast Asia

NASA Astrophysics Data System (ADS)

Frankel, R. J.

1981-05-01

A simple, inexpensive, and efficient method of water treatment for rural communities in Southeast Asia was developed using local materials as filter media. The filter utilizes coconut fiber and burnt rice husks in a two-stage filtering process designed as a gravityfed system without the need for backwashing, and eliminates in most cases the need of any chemicals. The first-stage filter with coconut fiber acts essentially as a substitute for the coagulation and sedimentation phases of conventional water-treatment plants. The second-stage filter, using burnt rice husks, is similar to slow sand filtration with the additional benefits of taste, color and odor removals through the absorption properties of the activated carbon in the medium. This paper reports on the design, construction costs, and operating results of several village size units in Thailand and in the Philippines.

Digitally Controllable Current Amplifier and Current Conveyors in Practical Application of Controllable Frequency Filter

NASA Astrophysics Data System (ADS)

Polak, Josef; Jerabek, Jan; Langhammer, Lukas; Sotner, Roman; Dvorak, Jan; Panek, David

2016-07-01

This paper presents the simulations results in comparison with the measured results of the practical realization of the multifunctional second order frequency filter with a Digitally Adjustable Current Amplifier (DACA) and two Dual-Output Controllable Current Conveyors (CCCII +/-). This filter is designed for use in current mode. The filter was designed of the single input multiple outputs (SIMO) type, therefore it has only one input and three outputs with individual filtering functions. DACA element used in a newly proposed circuit is present in form of an integrated chip and the current conveyors are implemented using the Universal Current Conveyor (UCC) chip with designation UCC-N1B. Proposed frequency filter enables independent control of the pole frequency using parameters of two current conveyors and also independent control of the quality factor by change of a current gain of DACA.

Hardware-efficient implementation of digital FIR filter using fast first-order moment algorithm

NASA Astrophysics Data System (ADS)

Cao, Li; Liu, Jianguo; Xiong, Jun; Zhang, Jing

2018-03-01

As the digital finite impulse response (FIR) filter can be transformed into the shift-add form of multiple small-sized firstorder moments, based on the existing fast first-order moment algorithm, this paper presents a novel multiplier-less structure to calculate any number of sequential filtering results in parallel. The theoretical analysis on its hardware and time-complexities reveals that by appropriately setting the degree of parallelism and the decomposition factor of a fixed word width, the proposed structure may achieve better area-time efficiency than the existing two-dimensional (2-D) memoryless-based filter. To evaluate the performance concretely, the proposed designs for different taps along with the existing 2-D memoryless-based filters, are synthesized by Synopsys Design Compiler with 0.18-μm SMIC library. The comparisons show that the proposed design has less area-time complexity and power consumption when the number of filter taps is larger than 48.

Teaching-learning-based Optimization Algorithm for Parameter Identification in the Design of IIR Filters

NASA Astrophysics Data System (ADS)

Singh, R.; Verma, H. K.

2013-12-01

This paper presents a teaching-learning-based optimization (TLBO) algorithm to solve parameter identification problems in the designing of digital infinite impulse response (IIR) filter. TLBO based filter modelling is applied to calculate the parameters of unknown plant in simulations. Unlike other heuristic search algorithms, TLBO algorithm is an algorithm-specific parameter-less algorithm. In this paper big bang-big crunch (BB-BC) optimization and PSO algorithms are also applied to filter design for comparison. Unknown filter parameters are considered as a vector to be optimized by these algorithms. MATLAB programming is used for implementation of proposed algorithms. Experimental results show that the TLBO is more accurate to estimate the filter parameters than the BB-BC optimization algorithm and has faster convergence rate when compared to PSO algorithm. TLBO is used where accuracy is more essential than the convergence speed.

A high-power spatial filter for Thomson scattering stray light reduction

NASA Astrophysics Data System (ADS)

Levesque, J. P.; Litzner, K. D.; Mauel, M. E.; Maurer, D. A.; Navratil, G. A.; Pedersen, T. S.

2011-03-01

The Thomson scattering diagnostic on the High Beta Tokamak-Extended Pulse (HBT-EP) is routinely used to measure electron temperature and density during plasma discharges. Avalanche photodiodes in a five-channel interference filter polychromator measure scattered light from a 6 ns, 800 mJ, 1064 nm Nd:YAG laser pulse. A low cost, high-power spatial filter was designed, tested, and added to the laser beamline in order to reduce stray laser light to levels which are acceptable for accurate Rayleigh calibration. A detailed analysis of the spatial filter design and performance is given. The spatial filter can be easily implemented in an existing Thomson scattering system without the need to disturb the vacuum chamber or significantly change the beamline. Although apertures in the spatial filter suffer substantial damage from the focused beam, with proper design they can last long enough to permit absolute calibration.

Multi-Bandwidth Frequency Selective Surfaces for Near Infrared Filtering: Design and Optimization

NASA Technical Reports Server (NTRS)

Cwik, Tom; Fernandez, Salvador; Ksendzov, A.; LaBaw, Clayton C.; Maker, Paul D.; Muller, Richard E.

1999-01-01

Frequency selective surfaces are widely used in the microwave and millimeter wave regions of the spectrum for filtering signals. They are used in telecommunication systems for multi-frequency operation or in instrument detectors for spectroscopy. The frequency selective surface operation depends on a periodic array of elements resonating at prescribed wavelengths producing a filter response. The size of the elements is on the order of half the electrical wavelength, and the array period is typically less than a wavelength for efficient operation. When operating in the optical region, diffraction gratings are used for filtering. In this regime the period of the grating may be several wavelengths producing multiple orders of light in reflection or transmission. In regions between these bands (specifically in the infrared band) frequency selective filters consisting of patterned metal layers fabricated using electron beam lithography are beginning to be developed. The operation is completely analogous to surfaces made in the microwave and millimeter wave region except for the choice of materials used and the fabrication process. In addition, the lithography process allows an arbitrary distribution of patterns corresponding to resonances at various wavelengths to be produced. The design of sub-millimeter filters follows the design methods used in the microwave region. Exacting modal matching, integral equation or finite element methods can be used for design. A major difference though is the introduction of material parameters and thicknesses tha_ may not be important in longer wavelength designs. This paper describes the design of multi-bandwidth filters operating in the I-5 micrometer wavelength range. This work follows on previous design [1,2]. In this paper extensions based on further optimization and an examination of the specific shape of the element in the periodic cell will be reported. Results from the design, manufacture and test of linear wedge filters built using micro-lithographic techniques and used ir spectral imaging applications will be presented.

Multi-Bandwidth Frequency Selective Surfaces for Near Infrared Filtering: Design and Optimization

NASA Technical Reports Server (NTRS)

Cwik, Tom; Fernandez, Salvador; Ksendzov, A.; LaBaw, Clayton C.; Maker, Paul D.; Muller, Richard E.

1998-01-01

Frequency selective surfaces are widely used in the microwave and millimeter wave regions of the spectrum for filtering signals. They are used in telecommunication systems for multi-frequency operation or in instrument detectors for spectroscopy. The frequency selective surface operation depends on a periodic array of elements resonating at prescribed wavelengths producing a filter response. The size of the elements is on the order of half the electrical wavelength, and the array period is typically less than a wavelength for efficient operation. When operating in the optical region, diffraction gratings are used for filtering. In this regime the period of the grating may be several wavelengths producing multiple orders of light in reflection or transmission. In regions between these bands (specifically in the infrared band) frequency selective filters consisting of patterned metal layers fabricated using electron beam lithography are beginning to be developed. The operation is completely analogous to surfaces made in the microwave and millimeter wave region except for the choice of materials used and the fabrication process. In addition, the lithography process allows an arbitrary distribution of patterns corresponding to resonances at various wavelengths to be produced. The design of sub-millimeter filters follows the design methods used in the microwave region. Exacting modal matching, integral equation or finite element methods can be used for design. A major difference though is the introduction of material parameters and thicknesses that may not be important in longer wavelength designs. This paper describes the design of multi- bandwidth filters operating in the 1-5 micrometer wavelength range. This work follows on a previous design. In this paper extensions based on further optimization and an examination of the specific shape of the element in the periodic cell will be reported. Results from the design, manufacture and test of linear wedge filters built using microlithographic techniques and used in spectral imaging applications will be presented.

ASME AG-1 Section FC Qualified HEPA Filters; a Particle Loading Comparison - 13435

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

Stillo, Andrew; Ricketts, Craig I.

High Efficiency Particulate Air (HEPA) Filters used to protect personnel, the public and the environment from airborne radioactive materials are designed, manufactured and qualified in accordance with ASME AG-1 Code section FC (HEPA Filters) [1]. The qualification process requires that filters manufactured in accordance with this ASME AG-1 code section must meet several performance requirements. These requirements include performance specifications for resistance to airflow, aerosol penetration, resistance to rough handling, resistance to pressure (includes high humidity and water droplet exposure), resistance to heated air, spot flame resistance and a visual/dimensional inspection. None of these requirements evaluate the particle loading capacitymore » of a HEPA filter design. Concerns, over the particle loading capacity, of the different designs included within the ASME AG-1 section FC code[1], have been voiced in the recent past. Additionally, the ability of a filter to maintain its integrity, if subjected to severe operating conditions such as elevated relative humidity, fog conditions or elevated temperature, after loading in use over long service intervals is also a major concern. Although currently qualified HEPA filter media are likely to have similar loading characteristics when evaluated independently, filter pleat geometry can have a significant impact on the in-situ particle loading capacity of filter packs. Aerosol particle characteristics, such as size and composition, may also have a significant impact on filter loading capacity. Test results comparing filter loading capacities for three different aerosol particles and three different filter pack configurations are reviewed. The information presented represents an empirical performance comparison among the filter designs tested. The results may serve as a basis for further discussion toward the possible development of a particle loading test to be included in the qualification requirements of ASME AG-1 Code sections FC and FK[1]. (authors)« less

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 dust particles on the filter surface and to facilitate dust removal with pulse or back airflow.

Virological Surveillance of Dengue in Saint Martin and Saint Barthélemy, French West Indies, Using Blood Samples on Filter Paper

PubMed Central

Matheus, Séverine; Chappert, Jean-Loup; Cassadou, Sylvie; Berger, Franck; Labeau, Bhetty; Bremand, Laetitia; Winicki, Alain; Huc-Anais, Patricia; Quenel, Philippe; Dussart, Philippe

2012-01-01

To strengthen active dengue surveillance in Saint Martin and Saint Barthélemy, two French Caribbean islands, we evaluated the epidemiological usefulness of collecting blood samples from NS1-positive dengue patients on filter paper to identify the dengue serotypes circulating in these regions during a 27-month period. This approach allowed dengue serotypes to be identified by reverse transcriptase-polymerase chain reaction in 90.1% of the total set of 666 samples analyzed and, in 95.5% of the samples collected during the acute phase of the disease. This prospective virological surveillance using blood samples absorbed onto filter paper, which were stored at 4°C and shipped at ambient temperature to a specialized laboratory for analysis, allowed us to avoid the logistic and financial costs associated with shipping frozen venous blood samples. This surveillance system offers a low-cost alternative for reinforcing dengue prevention in areas where specialized laboratories do not exist, notably by facilitating the early detection of potentially new dengue serotypes. PMID:22232467

Fractional Control of An Active Four-wheel-steering Vehicle

NASA Astrophysics Data System (ADS)

Wang, Tianting; Tong, Jun; Chen, Ning; Tian, Jie

2018-03-01

A four-wheel-steering (4WS) vehicle model and reference model with a drop filter are constructed. The decoupling of 4WS vehicle model is carried out. And a fractional PIλDμ controller is introduced into the decoupling strategy to reduce the effects of the uncertainty of the vehicle parameters as well as the unmodelled dynamics on the system performance. Based on optimization techniques, the design of fractional controller are obtained to ensure the robustness of 4WS vehicle during the special range of frequencies through proper choice of the constraints. In order to compare with fractional robust controller, an optimal controller for the same vehicle is also designed. The simulations of the two control systems are carried out and it reveals that the decoupling and fractional robust controller is able to make vehicle model trace the reference model very well with better robustness.

Improvement of the fringe analysis algorithm for wavelength scanning interferometry based on filter parameter optimization.

PubMed

Zhang, Tao; Gao, Feng; Muhamedsalih, Hussam; Lou, Shan; Martin, Haydn; Jiang, Xiangqian

2018-03-20

The phase slope method which estimates height through fringe pattern frequency and the algorithm which estimates height through the fringe phase are the fringe analysis algorithms widely used in interferometry. Generally they both extract the phase information by filtering the signal in frequency domain after Fourier transform. Among the numerous papers in the literature about these algorithms, it is found that the design of the filter, which plays an important role, has never been discussed in detail. This paper focuses on the filter design in these algorithms for wavelength scanning interferometry (WSI), trying to optimize the parameters to acquire the optimal results. The spectral characteristics of the interference signal are analyzed first. The effective signal is found to be narrow-band (near single frequency), and the central frequency is calculated theoretically. Therefore, the position of the filter pass-band is determined. The width of the filter window is optimized with the simulation to balance the elimination of the noise and the ringing of the filter. Experimental validation of the approach is provided, and the results agree very well with the simulation. The experiment shows that accuracy can be improved by optimizing the filter design, especially when the signal quality, i.e., the signal noise ratio (SNR), is low. The proposed method also shows the potential of improving the immunity to the environmental noise by adapting the signal to acquire the optimal results through designing an adaptive filter once the signal SNR can be estimated accurately.

Novel programmable microwave photonic filter with arbitrary filtering shape and linear phase.

PubMed

Zhu, Xiaoqi; Chen, Feiya; Peng, Huanfa; Chen, Zhangyuan

2017-04-17

We propose and demonstrate a novel optical frequency comb (OFC) based microwave photonic filter which is able to realize arbitrary filtering shape with linear phase response. The shape of filter response is software programmable using finite impulse response (FIR) filter design method. By shaping the OFC spectrum using a programmable waveshaper, we can realize designed amplitude of FIR taps. Positive and negative sign of FIR taps are achieved by balanced photo-detection. The double sideband (DSB) modulation and symmetric distribution of filter taps are used to maintain the linear phase condition. In the experiment, we realize a fully programmable filter in the range from DC to 13.88 GHz. Four basic types of filters (lowpass, highpass, bandpass and bandstop) with different bandwidths, cut-off frequencies and central frequencies are generated. Also a triple-passband filter is realized in our experiment. To the best of our knowledge, it is the first demonstration of a programmable multiple passband MPF with linear phase response. The experiment shows good agreement with the theoretical result.

A class of systolizable IIR digital filters and its design for proper scaling and minimum output roundoff noise

NASA Technical Reports Server (NTRS)

Lei, Shaw-Min; Yao, Kung

1990-01-01

A class of infinite impulse response (IIR) digital filters with a systolizable structure is proposed and its synthesis is investigated. The systolizable structure consists of pipelineable regular modules with local connections and is suitable for VLSI implementation. It is capable of achieving high performance as well as high throughput. This class of filter structure provides certain degrees of freedom that can be used to obtain some desirable properties for the filter. Techniques of evaluating the internal signal powers and the output roundoff noise of the proposed filter structure are developed. Based upon these techniques, a well-scaled IIR digital filter with minimum output roundoff noise is designed using a local optimization approach. The internal signals of all the modes of this filter are scaled to unity in the l2-norm sense. Compared to the Rao-Kailath (1984) orthogonal digital filter and the Gray-Markel (1973) normalized-lattice digital filter, this filter has better scaling properties and lower output roundoff noise.

Economical Implementation of a Filter Engine in an FPGA

NASA Technical Reports Server (NTRS)

Kowalski, James E.

2009-01-01

A logic design has been conceived for a field-programmable gate array (FPGA) that would implement a complex system of multiple digital state-space filters. The main innovative aspect of this design lies in providing for reuse of parts of the FPGA hardware to perform different parts of the filter computations at different times, in such a manner as to enable the timely performance of all required computations in the face of limitations on available FPGA hardware resources. The implementation of the digital state-space filter involves matrix vector multiplications, which, in the absence of the present innovation, would ordinarily necessitate some multiplexing of vector elements and/or routing of data flows along multiple paths. The design concept calls for implementing vector registers as shift registers to simplify operand access to multipliers and accumulators, obviating both multiplexing and routing of data along multiple paths. Each vector register would be reused for different parts of a calculation. Outputs would always be drawn from the same register, and inputs would always be loaded into the same register. A simple state machine would control each filter. The output of a given filter would be passed to the next filter, accompanied by a "valid" signal, which would start the state machine of the next filter. Multiple filter modules would share a multiplication/accumulation arithmetic unit. The filter computations would be timed by use of a clock having a frequency high enough, relative to the input and output data rate, to provide enough cycles for matrix and vector arithmetic operations. This design concept could prove beneficial in numerous applications in which digital filters are used and/or vectors are multiplied by coefficient matrices. Examples of such applications include general signal processing, filtering of signals in control systems, processing of geophysical measurements, and medical imaging. For these and other applications, it could be advantageous to combine compact FPGA digital filter implementations with other application-specific logic implementations on single integrated-circuit chips. An FPGA could readily be tailored to implement a variety of filters because the filter coefficients would be loaded into memory at startup.

Time-Reversal Based Range Extension Technique for Ultra-wideband (UWB) Sensors and Applications in Tactical Communications and Networking

DTIC Science & Technology

2009-04-16

the transmitted waveform, then spectral mask, notch line of Arbitrary Notch Filter , the designed waveforms and multipath impulse response represented...400 Frequence (MHz) Figure 5.4: Spectral mask, notch line of Arbitrary Notch Filter , the designed waveforms and multipath impulse response...600 Frequence (MHz) Figure 5.7: Spectral mask, notch line of Arbitrary Notch Filter , the designed waveforms and multipath impulse response

Design of recursive digital filters having specified phase and magnitude characteristics

NASA Technical Reports Server (NTRS)

King, R. E.; Condon, G. W.

1972-01-01

A method for a computer-aided design of a class of optimum filters, having specifications in the frequency domain of both magnitude and phase, is described. The method, an extension to the work of Steiglitz, uses the Fletcher-Powell algorithm to minimize a weighted squared magnitude and phase criterion. Results using the algorithm for the design of filters having specified phase as well as specified magnitude and phase compromise are presented.

Design and implementation of a hybrid digital phase-locked loop with a TMS320C25: An application to a transponder receiver breadboard

NASA Technical Reports Server (NTRS)

Yeh, H.-G.; Nguyen, T. M.

1994-01-01

Design, modeling, analysis, and simulation of a phase-locked loop (PLL) with a digital loop filter are presented in this article. A TMS320C25 digital signal processor (DSP) is used to implement this digital loop filter. In order to keep the compatibility, the main design goal was to replace the analog PLL (APLL) of the Deep-Space Transponder (DST) receiver breadboard's loop filter with a digital loop filter without changing anything else. This replacement results in a hybrid digital PLL (HDPLL). Both the original APLL and the designed HDPLL are Type I second-order systems. The real-time performance of the HDPLL and the receiver is provided and evaluated.

Optical filter for highlighting spectral features part I: design and development of the filter for discrimination of human skin with and without an application of cosmetic foundation.

PubMed

Nishino, Ken; Nakamura, Mutsuko; Matsumoto, Masayuki; Tanno, Osamu; Nakauchi, Shigeki

2011-03-28

Light reflected from an object's surface contains much information about its physical and chemical properties. Changes in the physical properties of an object are barely detectable in spectra. Conventional trichromatic systems, on the other hand, cannot detect most spectral features because spectral information is compressively represented as trichromatic signals forming a three-dimensional subspace. We propose a method for designing a filter that optically modulates a camera's spectral sensitivity to find an alternative subspace highlighting an object's spectral features more effectively than the original trichromatic space. We designed and developed a filter that detects cosmetic foundations on human face. Results confirmed that the filter can visualize and nondestructively inspect the foundation distribution.

Compact optical filter for dual-wavelength fluorescence-spectrometry based on enhanced transmission through metallic nano-slit array

NASA Astrophysics Data System (ADS)

Hu, X.; Zhan, L.; Xia, Y.

2009-03-01

A novel optical filter based on enhanced transmission through metallic nano-slit is proposed for dual-wavelength fluorescence-spectrometry. A special structure, sampled-period slit array, is utilized to meet the requirement of dual-wavelength transmission in this system. Structure parameters on the transmission property are analyzed by means of Fourier transformation. With the features both to enhance the fluorescence generation and to enhance light transmission, in addition with the feasibility for miniaturization, integration on one chip, and mass production, the proposed filters are promising for the realization of dual-wavelength fluorescence-spectrometry in micro-total-analysis-system.

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: IN-DRAIN TREATMENT DEVICE. HYDRO INTERNATIONAL UP-FLO™ FILTER

EPA Science Inventory

Verification testing of the Hydro International Up-Flo™ Filter with one filter module and CPZ Mix™ filter media was conducted at the Penn State Harrisburg Environmental Engineering Laboratory in Middletown, Pennsylvania. The Up-Flo™ Filter is designed as a passive, modular filtr...

Sand Type Filters for Swimming Pools. Standard No. 10, Revised October, 1966.

ERIC Educational Resources Information Center

National Sanitation Foundation, Ann Arbor, MI.

Sand type filters are covered in this standard. The filters described are intended to be designed and used specifically for swimming pool water filtration, both public and residential. Included are the basic components which are a necessary part of the sand type filter such as filter housing, upper and lower distribution systems filter media,…

Design of almost symmetric orthogonal wavelet filter bank via direct optimization.

PubMed

Murugesan, Selvaraaju; Tay, David B H

2012-05-01

It is a well-known fact that (compact-support) dyadic wavelets [based on the two channel filter banks (FBs)] cannot be simultaneously orthogonal and symmetric. Although orthogonal wavelets have the energy preservation property, biorthogonal wavelets are preferred in image processing applications because of their symmetric property. In this paper, a novel method is presented for the design of almost symmetric orthogonal wavelet FB. Orthogonality is structurally imposed by using the unnormalized lattice structure, and this leads to an objective function, which is relatively simple to optimize. The designed filters have good frequency response, flat group delay, almost symmetric filter coefficients, and symmetric wavelet function.

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, with 50-GHz bandwidth, were designed, each using multiple transmission line media such as microstrip, coplanar waveguide, and quasi-lumped components on 0.45- m thick silicon. In the design process, modeling issues had to be overcome. Due to the extremely high frequencies, very thin Si substrate, and the superconducting metal layers, most commercially available software fails in various ways. These issues were mitigated by using alternative software that was capable of handling them at the expense of greater simulation time. The design of on-chip components for the filter characterization, such as a broadband antenna, Wilkinson power dividers, attenuators, detectors, and transitions has been completed.

Phage-based biomolecular filter for the capture of bacterial pathogens in liquid streams

NASA Astrophysics Data System (ADS)

Du, Songtao; Chen, I.-Hsuan; Horikawa, Shin; Lu, Xu; Liu, Yuzhe; Wikle, Howard C.; Suh, Sang Jin; Chin, Bryan A.

2017-05-01

This paper investigates a phage-based biomolecular filter that enables the evaluation of large volumes of liquids for the presence of small quantities of bacterial pathogens. The filter is a planar arrangement of phage-coated, strip-shaped magnetoelastic (ME) biosensors (4 mm × 0.8 mm × 0.03 mm), magnetically coupled to a filter frame structure, through which a liquid of interest flows. This "phage filter" is designed to capture specific bacterial pathogens and allow non-specific debris to pass, eliminating the common clogging issue in conventional bead filters. ANSYS Maxwell was used to simulate the magnetic field pattern required to hold ME biosensors densely and to optimize the frame design. Based on the simulation results, a phage filter structure was constructed, and a proof-in-concept experiment was conducted where a Salmonella solution of known concentration were passed through the filter, and the number of captured Salmonella was quantified by plate counting.

Resilient filtering for time-varying stochastic coupling networks under the event-triggering scheduling

NASA Astrophysics Data System (ADS)

Wang, Fan; Liang, Jinling; Dobaie, Abdullah M.

2018-07-01

The resilient filtering problem is considered for a class of time-varying networks with stochastic coupling strengths. An event-triggered strategy is adopted to save the network resources by scheduling the signal transmission from the sensors to the filters based on certain prescribed rules. Moreover, the filter parameters to be designed are subject to gain perturbations. The primary aim of the addressed problem is to determine a resilient filter that ensures an acceptable filtering performance for the considered network with event-triggering scheduling. To handle such an issue, an upper bound on the estimation error variance is established for each node according to the stochastic analysis. Subsequently, the resilient filter is designed by locally minimizing the derived upper bound at each iteration. Moreover, rigorous analysis shows the monotonicity of the minimal upper bound regarding the triggering threshold. Finally, a simulation example is presented to show effectiveness of the established filter scheme.

Seeing High in the Sky

NASA Image and Video Library

2006-01-06

In this magnificent view, delicate haze layers high in the atmosphere encircle the oblate figure of Saturn. A special combination of spectral filters used for this image makes the high haze become visible

X-band preamplifier filter

NASA Technical Reports Server (NTRS)

Manshadi, F.

1986-01-01

A low-loss bandstop filter designed and developed for the Deep Space Network's 34-meter high-efficiency antennas is described. The filter is used for protection of the X-band traveling wave masers from the 20-kW transmitter signal. A combination of empirical and theoretical techniques was employed as well as computer simulation to verify the design before fabrication.

Cryogenic filter wheel design for an infrared instrument

NASA Astrophysics Data System (ADS)

Azcue, Joaquín.; Villanueva, Carlos; Sánchez, Antonio; Polo, Cristina; Reina, Manuel; Carretero, Angel; Torres, Josefina; Ramos, Gonzalo; Gonzalez, Luis M.; Sabau, Maria D.; Najarro, Francisco; Pintado, Jesús M.

2014-09-01

In the last two decades, Spain has built up a strong IR community which has successfully contributed to space instruments, reaching Co-PI level in the SPICA mission (Space Infrared Telescope for Cosmology and Astrophysics). Under the SPICA mission, INTA, focused on the SAFARI instrument requirements but highly adaptable to other missions has designed a cryogenic low dissipation filter wheel with six positions, taking as starting point the past experience of the team with the OSIRIS instrument (ROSETTA mission) filter wheels and adapting the design to work at cryogenic temperatures. One of the main goals of the mechanism is to use as much as possible commercial components and test them at cryogenic temperature. This paper is focused on the design of the filter wheel, including the material selection for each of the main components of the mechanism, the design of elastic mount for the filter assembly, a positioner device designed to provide positional accuracy and repeatability to the filter, allowing the locking of the position without dissipation. In order to know the position of the wheel on every moment a position sensor based on a Hall sensor was developed. A series of cryogenic tests have been performed in order to validate the material configuration selected, the ball bearing lubrication and the selection of the motor. A stepper motor characterization campaign was performed including heat dissipation measurements. The result is a six position filter wheel highly adaptable to different configurations and motors using commercial components. The mechanism was successfully tested at INTA facilities at 20K at breadboard level.

Fixed-frequency and Frequency-agile (au, HTS) Microstrip Bandstop Filters for L-band Applications

NASA Technical Reports Server (NTRS)

Saenz, Eileen M.; Subramanyam, Guru; VanKeuls, Fred W.; Chen, Chonglin; Miranda, Felix A.

2001-01-01

In this work, we report on the performance of a highly selective, compact 1.83 x 2.08 cm(exp 2) (approx. 0.72 x 0.82 in(exp 2) microstrip line bandstop filter of YBa2CU3O(7-delta) (YBCO) on LaAlO3 (LAO) substrate. The filter is designed for a center frequency of 1.623 GHz for a bandwidth at 3 dB from reference baseline of less than 5.15 MHz, and a bandstop rejection of 30 dB or better. The design and optimization of the filter was performed using Zeland's IE3D circuit simulator. The optimized design was used to fabricate gold (Au) and High-Temperature Superconductor (HTS) versions of the filter. We have also studied an electronically tunable version of the same filter. Tunability of the bandstop characteristics is achieved by the integration of a thin film conductor (Au or HTS) and the nonlinear dielectric ferroelectric SrTiO3 in a conductor/ferroelectric/dielectric modified microstrip configuration. The performance of these filters and comparison with the simulated data will be presented.

Spatial filters for high-peak-power multistage laser amplifiers.

PubMed

Potemkin, A K; Barmashova, T V; Kirsanov, A V; Martyanov, M A; Khazanov, E A; Shaykin, A A

2007-07-10

We describe spatial filters used in a Nd:glass laser with an output pulse energy up to 300 J and a pulse duration of 1 ns. This laser is designed for pumping of a chirped-pulse optical parametric amplifier. We present data required to choose the shape and diameter of a spatial filter lens, taking into account aberrations caused by spherical surfaces. Calculation of the optimal pinhole diameter is presented. Design features of the spatial filters and the procedure of their alignment are discussed in detail.

Filter line wiring designs in aircraft

NASA Astrophysics Data System (ADS)

Rowe, Richard M.

1990-10-01

The paper presents a harness design using a filter-line wire technology and appropriate termination methods to help meet high-energy radiated electromagnetic field (HERF) requirements for protection against the adverse effects of EMI on electrical and avionic systems. Filter-line interconnect harnessing systems discussed consist of high-performance wires and cables; when properly wired they suppress conducted and radiated EMI above 100 MHz. Filter-line termination devices include backshell adapters, braid splicers, and shield terminators providing 360-degree low-impedance terminations and enhancing maintainability of the system.

Acoustic Wave Filter Technology-A Review.

PubMed

Ruppel, Clemens C W

2017-09-01

Today, acoustic filters are the filter technology to meet the requirements with respect to performance dictated by the cellular phone standards and their form factor. Around two billion cellular phones are sold every year, and smart phones are of a very high percentage of approximately two-thirds. Smart phones require a very high number of filter functions ranging from the low double-digit range up to almost triple digit numbers in the near future. In the frequency range up to 1 GHz, surface acoustic wave (SAW) filters are almost exclusively employed, while in the higher frequency range, bulk acoustic wave (BAW) and SAW filters are competing for their shares. Prerequisites for the success of acoustic filters were the availability of high-quality substrates, advanced and highly reproducible fabrication technologies, optimum filter techniques, precise simulation software, and advanced design tools that allow the fast and efficient design according to customer specifications. This paper will try to focus on innovations leading to high volume applications of intermediate frequency (IF) and radio frequency (RF) acoustic filters, e.g., TV IF filters, IF filters for cellular phones, and SAW/BAW RF filters for the RF front-end of cellular phones.

Indium phosphide all air-gap Fabry-Pérot filters for near-infrared spectroscopic applications

NASA Astrophysics Data System (ADS)

Ullah, A.; Butt, M. A.; Fomchenkov, S. A.; Khonina, S. N.

2016-08-01

Food quality can be characterized by noninvasive techniques such as spectroscopy in the Near Infrared wavelength range. For example, 930 -1450 nm wavelength range can be used to detect diseases and differentiate between meat samples. Miniaturization of such NIR spectrometers is useful for quick and mobile characterization of food samples. Spectrometers can be miniaturized, without compromising the spectral resolution, using Fabry-Pérot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. The most commonly used mirrors in the design of FP filters are Distributed Bragg Reflections (DBRs) consisting of alternating high and low refractive index material pairs, due to their high reflectivity compared to metal mirrors. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer detector. Therefore, a bandpass filter is usually required to restrict wavelengths outside the stopband of the FP DBRs. Such bandpass filters are difficult to design and implement. Alternatively, high index contrast materials must be can be used to broaden the stopband width of the FP DBRs. In this work, Indium phosphide all air-gap filters are proposed in conjunction with InGaAs based detectors. The designed filter has a wide stopband covering the entire InGaAs detector sensitivity range. The filter can be tuned in the 950-1450 nm with single mode operation. The designed filter can hence be used for noninvasive meat quality control.

Environmentally and economically efficient utilization of coal processing waste.

PubMed

Dmitrienko, Margarita A; Strizhak, Pavel A

2017-11-15

High concentrations of hazardous anthropogenic emissions (sulfur, nitrogen and carbon oxides) from solid fuel combustion in coal burning plants cause environmental problems that have been especially pressing over the last 20-30 years. A promising solution to these problems is a switch from conventional pulverized coal combustion to coal-water slurry fuel. In this paper, we pay special attention to the environmental indicators characterizing the combustion of different coal ranks (gas, flame, coking, low-caking, and nonbaking coals) and coal-water slurry fuels based on the coal processing waste - filter cakes. There have been no consistent data so far on the acceptable intervals for the anthropogenic emissions of sulfur (SO x ), nitrogen (NO x ) and carbon (CO, CO 2 ) oxides. Using a specialized combustion chamber and gas analyzing system, we have measured the concentrations of typical coal and filter-cake-based CWS combustion products. We have also calculated the typical combustion heat of the fuels under study and measured the ratio between environmental and energy attributes. The research findings show that the use of filter cakes in the form of CWS is even better than coals in terms of environment and economy. Wide utilization of filter cakes solves many environmental problems: the areas of contaminated sites shrink, anthropogenic emissions decrease, and there is no need to develop new coal mines anymore. Copyright © 2017 Elsevier B.V. All rights reserved.

Model Adaptation for Prognostics in a Particle Filtering Framework

NASA Technical Reports Server (NTRS)

Saha, Bhaskar; Goebel, Kai Frank

2011-01-01

One of the key motivating factors for using particle filters for prognostics is the ability to include model parameters as part of the state vector to be estimated. This performs model adaptation in conjunction with state tracking, and thus, produces a tuned model that can used for long term predictions. This feature of particle filters works in most part due to the fact that they are not subject to the "curse of dimensionality", i.e. the exponential growth of computational complexity with state dimension. However, in practice, this property holds for "well-designed" particle filters only as dimensionality increases. This paper explores the notion of wellness of design in the context of predicting remaining useful life for individual discharge cycles of Li-ion batteries. Prognostic metrics are used to analyze the tradeoff between different model designs and prediction performance. Results demonstrate how sensitivity analysis may be used to arrive at a well-designed prognostic model that can take advantage of the model adaptation properties of a particle filter.

Design of adaptive control systems by means of self-adjusting transversal filters

NASA Technical Reports Server (NTRS)

Merhav, S. J.

1986-01-01

The design of closed-loop adaptive control systems based on nonparametric identification was addressed. Implementation is by self-adjusting Least Mean Square (LMS) transversal filters. The design concept is Model Reference Adaptive Control (MRAC). Major issues are to preserve the linearity of the error equations of each LMS filter, and to prevent estimation bias that is due to process or measurement noise, thus providing necessary conditions for the convergence and stability of the control system. The controlled element is assumed to be asymptotically stable and minimum phase. Because of the nonparametric Finite Impulse Response (FIR) estimates provided by the LMS filters, a-priori information on the plant model is needed only in broad terms. Following a survey of control system configurations and filter design considerations, system implementation is shown here in Single Input Single Output (SISO) format which is readily extendable to multivariable forms. In extensive computer simulation studies the controlled element is represented by a second-order system with widely varying damping, natural frequency, and relative degree.

Filters for the International Solar Terrestrial Physics (ISTP) mission far ultraviolet imager

NASA Technical Reports Server (NTRS)

Zukic, Muamer; Torr, Douglas G.; Kim, Jongmin; Spann, James F.; Torr, Marsha R.

1993-01-01

The far ultraviolet (FUV) imager for the International Solar Terrestrial Physics (ISTP) mission is designed to image four features of the aurora: O I lines at 130.4 nm and 135.6 nm and the N2 Lyman-Birge-Hopfield (LBH) bands between 140 nm - 160 nm (LBH long) and 160 nm - 180 nm (LBH long). In this paper we report the design and fabrication of narrow-band and broadband filters for the ISTP FUV imager. Narrow-band filters designed and fabricated for the O I lines have a bandwidth of less than 5 nm and a peak transmittance of 23.9 percent and 38.3 percent at 130.4 nm and 135.6 nm, respectively. Broadband filters designed and fabricated for LBH bands have the transmittance close to 60 percent. Blocking of out-of-band wavelengths for all filters is better than 5x10(exp -3) percent with the transmittance at 121.6 nm of less than 10(exp -6) percent.

Optimal Sharpening of Compensated Comb Decimation Filters: Analysis and Design

PubMed Central

Troncoso Romero, David Ernesto

2014-01-01

Comb filters are a class of low-complexity filters especially useful for multistage decimation processes. However, the magnitude response of comb filters presents a droop in the passband region and low stopband attenuation, which is undesirable in many applications. In this work, it is shown that, for stringent magnitude specifications, sharpening compensated comb filters requires a lower-degree sharpening polynomial compared to sharpening comb filters without compensation, resulting in a solution with lower computational complexity. Using a simple three-addition compensator and an optimization-based derivation of sharpening polynomials, we introduce an effective low-complexity filtering scheme. Design examples are presented in order to show the performance improvement in terms of passband distortion and selectivity compared to other methods based on the traditional Kaiser-Hamming sharpening and the Chebyshev sharpening techniques recently introduced in the literature. PMID:24578674

Optimal sharpening of compensated comb decimation filters: analysis and design.

PubMed

Troncoso Romero, David Ernesto; Laddomada, Massimiliano; Jovanovic Dolecek, Gordana

2014-01-01

Comb filters are a class of low-complexity filters especially useful for multistage decimation processes. However, the magnitude response of comb filters presents a droop in the passband region and low stopband attenuation, which is undesirable in many applications. In this work, it is shown that, for stringent magnitude specifications, sharpening compensated comb filters requires a lower-degree sharpening polynomial compared to sharpening comb filters without compensation, resulting in a solution with lower computational complexity. Using a simple three-addition compensator and an optimization-based derivation of sharpening polynomials, we introduce an effective low-complexity filtering scheme. Design examples are presented in order to show the performance improvement in terms of passband distortion and selectivity compared to other methods based on the traditional Kaiser-Hamming sharpening and the Chebyshev sharpening techniques recently introduced in the literature.

FILTER PLANT DESIGN FOR ASBESTOS FIBER REMOVAL

EPA Science Inventory

Water filtration plants used to remove asbestos fibers should be designed to produce filtered water with very low turbidity (0.10 ntu or lower). Flexibility in plant operation, especially with respect to conditioning raw water for filtration, is a key design factor. Preconditioni...

LSST Camera Optics Design

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

Riot, V J; Olivier, S; Bauman, B

2012-05-24

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope mirrors to optimize performance. We discuss the rationale for the LSST camera optics design, describe the methodology for fabricating, coating, mounting and testing the lenses and filters, and present the results of detailed analyses demonstrating that the camera optics willmore » meet their performance goals.« less

A novel low-complexity digital filter design for wearable ECG devices

PubMed Central

Mehrnia, Alireza

2017-01-01

Wearable and implantable Electrocardiograph (ECG) devices are becoming prevailing tools for continuous real-time personal health monitoring. The ECG signal can be contaminated by various types of noise and artifacts (e.g., powerline interference, baseline wandering) that must be removed or suppressed for accurate ECG signal processing. Limited device size, power consumption and cost are critical issues that need to be carefully considered when designing any portable health monitoring device, including a battery-powered ECG device. This work presents a novel low-complexity noise suppression reconfigurable finite impulse response (FIR) filter structure for wearable ECG and heart monitoring devices. The design relies on a recently introduced optimally-factored FIR filter method. The new filter structure and several of its useful features are presented in detail. We also studied the hardware complexity of the proposed structure and compared it with the state-of-the-art. The results showed that the new ECG filter has a lower hardware complexity relative to the state-of-the-art ECG filters. PMID:28384272

Optimizing binary phase and amplitude filters for PCE, SNR, and discrimination

NASA Technical Reports Server (NTRS)

Downie, John D.

1992-01-01

Binary phase-only filters (BPOFs) have generated much study because of their implementation on currently available spatial light modulator devices. On polarization-rotating devices such as the magneto-optic spatial light modulator (SLM), it is also possible to encode binary amplitude information into two SLM transmission states, in addition to the binary phase information. This is done by varying the rotation angle of the polarization analyzer following the SLM in the optical train. Through this parameter, a continuum of filters may be designed that span the space of binary phase and amplitude filters (BPAFs) between BPOFs and binary amplitude filters. In this study, we investigate the design of optimal BPAFs for the key correlation characteristics of peak sharpness (through the peak-to-correlation energy (PCE) metric), signal-to-noise ratio (SNR), and discrimination between in-class and out-of-class images. We present simulation results illustrating improvements obtained over conventional BPOFs, and trade-offs between the different performance criteria in terms of the filter design parameter.

A novel low-complexity digital filter design for wearable ECG devices.

PubMed

Asgari, Shadnaz; Mehrnia, Alireza

2017-01-01

Wearable and implantable Electrocardiograph (ECG) devices are becoming prevailing tools for continuous real-time personal health monitoring. The ECG signal can be contaminated by various types of noise and artifacts (e.g., powerline interference, baseline wandering) that must be removed or suppressed for accurate ECG signal processing. Limited device size, power consumption and cost are critical issues that need to be carefully considered when designing any portable health monitoring device, including a battery-powered ECG device. This work presents a novel low-complexity noise suppression reconfigurable finite impulse response (FIR) filter structure for wearable ECG and heart monitoring devices. The design relies on a recently introduced optimally-factored FIR filter method. The new filter structure and several of its useful features are presented in detail. We also studied the hardware complexity of the proposed structure and compared it with the state-of-the-art. The results showed that the new ECG filter has a lower hardware complexity relative to the state-of-the-art ECG filters.

Determination of tailored filter sets to create rayfiles including spatial and angular resolved spectral information.

PubMed

Rotscholl, Ingo; Trampert, Klaus; Krüger, Udo; Perner, Martin; Schmidt, Franz; Neumann, Cornelius

2015-11-16

To simulate and optimize optical designs regarding perceived color and homogeneity in commercial ray tracing software, realistic light source models are needed. Spectral rayfiles provide angular and spatial varying spectral information. We propose a spectral reconstruction method with a minimum of time consuming goniophotometric near field measurements with optical filters for the purpose of creating spectral rayfiles. Our discussion focuses on the selection of the ideal optical filter combination for any arbitrary spectrum out of a given filter set by considering measurement uncertainties with Monte Carlo simulations. We minimize the simulation time by a preselection of all filter combinations, which bases on factorial design.

Imaging spectrometer using a liquid crystal tunable filter

NASA Astrophysics Data System (ADS)

Chrien, Thomas G.; Chovit, Christopher; Miller, Peter J.

1993-09-01

A demonstration imaging spectrometer using a liquid crystal tunable filter (LCTF) was built and tested on a hot air balloon platform. The LCTF is a tunable polarization interference or Lyot filter. The LCTF enables a small, light weight, low power, band sequential imaging spectrometer design. An overview of the prototype system is given along with a description of balloon experiment results. System model performance predictions are given for a future LCTF based imaging spectrometer design. System design considerations of LCTF imaging spectrometers are discussed.

Design optimization of integrated BiDi triplexer optical filter based on planar lightwave circuit.

PubMed

Xu, Chenglin; Hong, Xiaobin; Huang, Wei-Ping

2006-05-29

Design optimization of a novel integrated bi-directional (BiDi) triplexer filter based on planar lightwave circuit (PLC) for fiber-to-the premise (FTTP) applications is described. A multi-mode interference (MMI) device is used to filter the up-stream 1310nm signal from the down-stream 1490nm and 1555nm signals. An array waveguide grating (AWG) device performs the dense WDM function by further separating the two down-stream signals. The MMI and AWG are built on the same substrate with monolithic integration. The design is validated by simulation, which shows excellent performance in terms of filter spectral characteristics (e.g., bandwidth, cross-talk, etc.) as well as insertion loss.

Design optimization of integrated BiDi triplexer optical filter based on planar lightwave circuit

NASA Astrophysics Data System (ADS)

Xu, Chenglin; Hong, Xiaobin; Huang, Wei-Ping

2006-05-01

Design optimization of a novel integrated bi-directional (BiDi) triplexer filter based on planar lightwave circuit (PLC) for fiber-to-the premise (FTTP) applications is described. A multi-mode interference (MMI) device is used to filter the up-stream 1310nm signal from the down-stream 1490nm and 1555nm signals. An array waveguide grating (AWG) device performs the dense WDM function by further separating the two down-stream signals. The MMI and AWG are built on the same substrate with monolithic integration. The design is validated by simulation, which shows excellent performance in terms of filter spectral characteristics (e.g., bandwidth, cross-talk, etc.) as well as insertion loss.

An ultra-low-power filtering technique for biomedical applications.

PubMed

Zhang, Tan-Tan; Mak, Pui-In; Vai, Mang-I; Mak, Peng-Un; Wan, Feng; Martins, R P

2011-01-01

This paper describes an ultra-low-power filtering technique for biomedical applications designated as T-wave sensing in heart-activities detection systems. The topology is based on a source-follower-based Biquad operating in the sub-threshold region. With the intrinsic advantages of simplicity and high linearity of the source-follower, ultra-low-cutoff filtering can be achieved, simultaneously with ultra low power and good linearity. An 8(th)-order 2.4-Hz lowpass filter design example optimized in a 0.35-μm CMOS process was designed achieving over 85-dB dynamic range, 74-dB stopband attenuation and consuming only 0.36 nW at a 3-V supply.

Design of a terahertz photonic crystal transmission filter containing ferroelectric material.

PubMed

King, Tzu-Chyang; Chen, Jian-Jie; Chang, Kai-Chun; Wu, Chien-Jang

2016-10-10

The ferroelectric material KTaO₃ (KTO) has a very high refractive index, which is advantageous to the photonic crystal (PC) design. KTO polycrystalline crystal has a high extinction coefficient. In this work, we perform a theoretical study of the transmission properties of a PC bandpass filter made of polycrystalline KTO at terahertz (THz) frequencies. Our results show that the defect modes of usual PC narrowband filters no longer exist because of the existence of the high loss. We provide a new PC structure for the high-extinction materials and show that it has defect modes in its transmittance spectra, providing a possible bandpass filter design in the THz region.

Photonic compressed sensing nyquist folding receiver

DTIC Science & Technology

2017-09-01

filter . Two independent photonic receiver architectures are designed and analyzed over the course of this research. Both receiver designs are...undersamples the signals using an opti- cal modulator configuration at 1550 nm and collects the detected samples in a low pass interpolation filter ...Electronic Intelligence EW Electronic Warfare FM Frequency Modulated LNA Low Noise Amplifier LPF Low Pass Filter MZI Mach-Zehnder Interferometer NYFR Nyquist

Electronic stethoscope with frequency shaping and infrasonic recording capabilities.

PubMed

Gordon, E S; Lagerwerff, J M

1976-03-01

A small electronic stethoscope with variable frequency response characteristics has been developed for aerospace and research applications. The system includes a specially designed piezoelectric pickup and amplifier with an overall frequency response from 0.7 to 5,000 HZ (-3 dB points) and selective bass and treble boost or cut of up to 15 dB. A steep slope, high pass filter can be switched in for ordinary clinical auscultation without overload distortion from strong infrasonic signal inputs. A commercial stethoscope-type headset, selected for best overall response, is used which can adequately handle up to 100 mW of audio power delivered from the amplifier. The active components of the amplifier consist of only four opamp-type integrated circuits.

Effects of aeolian erosion on microbial release from solids.

NASA Technical Reports Server (NTRS)

Gustan, E. A.; Olson, R. L.; Taylor, D. M.; Green, R. H.

1972-01-01

This study was initiated to determine the percentage of spores that would be expected to be released from the interior of solid materials by aeolian erosion on a planetary surface. Methyl methacrylate and Eccobond disks were fabricated so that each disk contained approximately 40,000 Bacillus subtilis var. niger spores. The disks were placed in a specially designed sandblasting device and eroded. Exposure periods of 0.5, 2 and 24 hours were investigated using filtered air to accelerate the sand. A series of tests was also conducted for a 0.5 hour period using carbon dioxide. Examination of the erosion products showed that less than 1% of the spores originally contained in the solids was released by aeolian erosion.

Antenna-Coupled Bolometer Arrays for Astrophysics

NASA Astrophysics Data System (ADS)

Bock, James

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

Continuous 1052, 1064 nm dual-wavelength Nd:YAG laser

NASA Astrophysics Data System (ADS)

Wang, Xiaozhong; Yuan, Haiyang; Wang, Mingshan; Huang, Wencai

2016-10-01

Dual-wavelength lasers are usually obtained through balancing the net gain of the two oscillating lines. Competition between transitions 1052 nm, 1061 nm and 1064 nm is utilized to realize a continuous wave 1052 and 1064 nm dual-wavelength Nd:YAG laser firstly in this paper. A specially designed Fabry-Perot band-pass filter is exploited as output coupler to control the thresholds of the oscillating wavelengths. The maximum power of the dual-wavelength laser is 1.6 W and the slope efficiency is about 10%. The power instability of the output dual-wavelength laser is smaller than ±4% in half an hour. The mechanism presented in this paper may provide a new way to obtain dual-wavelength lasers.

Evolution of an interfacial crack on the concrete-embankment boundary

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

Glascoe, Lee; Antoun, Tarabay; Kanarska, Yuliya

2013-07-10

Failure of a dam can have subtle beginnings. A small crack or dislocation at the interface of the concrete dam and the surrounding embankment soil initiated by, for example, a seismic or an explosive event can lead to a catastrophic failure of the dam. The dam may ‘self-rehabilitate’ if a properly designed granular filter is engineered around the embankment. Currently, the design criteria for such filters have only been based on experimental studies. We demonstrate the numerical prediction of filter effectiveness at the soil grain scale. This joint LLNL-ERDC basic research project, funded by the Department of Homeland Security’s Sciencemore » and Technology Directorate (DHS S&T), consists of validating advanced high performance computer simulations of soil erosion and transport of grain- and dam-scale models to detailed centrifuge and soil erosion tests. Validated computer predictions highlight that a resilient filter is consistent with the current design specifications for dam filters. These predictive simulations, unlike the design specifications, can be used to assess filter success or failure under different soil or loading conditions and can lead to meaningful estimates of the timing and nature of full-scale dam failure.« less

Linking landscape characteristics to mineral site use by band-tailed pigeons in Western Oregon: Coarse-filter conservation with fine-filter tuning

USGS Publications Warehouse

Overton, C.T.; Schmitz, R.A.; Casazza, Michael L.

2006-01-01

Mineral sites are scarce resources of high ion concentration used heavily by the Pacific Coast subpopulation of band-tailed pigeons. Over 20% of all known mineral sites used by band-tailed pigeons in western Oregon, including all hot springs, have been abandoned. Prior investigations have not analyzed stand or landscape level habitat composition in relation to band-tailed pigeon use of mineral sites. We used logistic regression models to evaluate the influence of habitat types, identified from Gap Analysis Program (GAP) products at two spatial scales, on the odds of mineral site use in Oregon (n = 69 currently used and 20 historically used). Our results indicated that the odds of current use were negatively associated with non-forested terrestrial and private land area around mineral sites. Similarly, the odds of current mineral site use were positively associated with forested and special status (GAP stewardship codes 1 and 2) land area. The most important variable associated with the odds of mineral site use was the amount of non-forested land cover at either spatial scale. Our results demonstrate the utility of meso-scale geographic information designed for regional, coarse-filter approaches to conservation in fine-filter investigation of wildlife-habitat relationships. Adjacent landcover and ownership status explain the pattern of use for known mineral sites in western Oregon. In order for conservation and management activities for band-tailed pigeons to be successful, mineral sites need to be addressed as important and vulnerable resources. Management of band-tailed pigeons should incorporate the potential for forest management activities and land ownership patterns to influence the risk of mineral site abandonment.

A Unified Fisher's Ratio Learning Method for Spatial Filter Optimization.

PubMed

Li, Xinyang; Guan, Cuntai; Zhang, Haihong; Ang, Kai Keng

To detect the mental task of interest, spatial filtering has been widely used to enhance the spatial resolution of electroencephalography (EEG). However, the effectiveness of spatial filtering is undermined due to the significant nonstationarity of EEG. Based on regularization, most of the conventional stationary spatial filter design methods address the nonstationarity at the cost of the interclass discrimination. Moreover, spatial filter optimization is inconsistent with feature extraction when EEG covariance matrices could not be jointly diagonalized due to the regularization. In this paper, we propose a novel framework for a spatial filter design. With Fisher's ratio in feature space directly used as the objective function, the spatial filter optimization is unified with feature extraction. Given its ratio form, the selection of the regularization parameter could be avoided. We evaluate the proposed method on a binary motor imagery data set of 16 subjects, who performed the calibration and test sessions on different days. The experimental results show that the proposed method yields improvement in classification performance for both single broadband and filter bank settings compared with conventional nonunified methods. We also provide a systematic attempt to compare different objective functions in modeling data nonstationarity with simulation studies.To detect the mental task of interest, spatial filtering has been widely used to enhance the spatial resolution of electroencephalography (EEG). However, the effectiveness of spatial filtering is undermined due to the significant nonstationarity of EEG. Based on regularization, most of the conventional stationary spatial filter design methods address the nonstationarity at the cost of the interclass discrimination. Moreover, spatial filter optimization is inconsistent with feature extraction when EEG covariance matrices could not be jointly diagonalized due to the regularization. In this paper, we propose a novel framework for a spatial filter design. With Fisher's ratio in feature space directly used as the objective function, the spatial filter optimization is unified with feature extraction. Given its ratio form, the selection of the regularization parameter could be avoided. We evaluate the proposed method on a binary motor imagery data set of 16 subjects, who performed the calibration and test sessions on different days. The experimental results show that the proposed method yields improvement in classification performance for both single broadband and filter bank settings compared with conventional nonunified methods. We also provide a systematic attempt to compare different objective functions in modeling data nonstationarity with simulation studies.

Design considerations for near-infrared filter photometry: effects of noise sources and selectivity.

PubMed

Tarumi, Toshiyasu; Amerov, Airat K; Arnold, Mark A; Small, Gary W

2009-06-01

Optimal filter design of two-channel near-infrared filter photometers is investigated for simulated two-component systems consisting of an analyte and a spectrally overlapping interferent. The degree of overlap between the analyte and interferent bands is varied over three levels. The optimal design is obtained for three cases: a source or background flicker noise limited case, a shot noise limited case, and a detector noise limited case. Conventional photometers consist of narrow-band optical filters with their bands located at discrete wavelengths. However, the use of broadband optical filters with overlapping responses has been proposed to obtain as much signal as possible from a weak and broad analyte band typical of near-infrared absorptions. One question regarding the use of broadband optical filters with overlapping responses is the selectivity achieved by such filters. The selectivity of two-channel photometers is evaluated on the basis of the angle between the analyte and interferent vectors in the space spanned by the relative change recorded for each of the two detector channels. This study shows that for the shot noise limited or detector noise limited cases, the slight decrease in selectivity with the use of broadband optical filters can be compensated by the higher signal-to-noise ratio afforded by the use of such filters. For the source noise limited case, the best quantitative results are obtained with the use of narrow-band non-overlapping optical filters.

Giardia and Drinking Water from Private Wells

MedlinePlus

... boiling water is using a point-of-use filter. Not all home water filters remove Giardia . Filters that are designed to remove the parasite should ... learn more, visit CDC’s A Guide to Water Filters page. As you consider ways to disinfect your ...

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.

Adapted all-numerical correlator for face recognition applications

NASA Astrophysics Data System (ADS)

Elbouz, M.; Bouzidi, F.; Alfalou, A.; Brosseau, C.; Leonard, I.; Benkelfat, B.-E.

2013-03-01

In this study, we suggest and validate an all-numerical implementation of a VanderLugt correlator which is optimized for face recognition applications. The main goal of this implementation is to take advantage of the benefits (detection, localization, and identification of a target object within a scene) of correlation methods and exploit the reconfigurability of numerical approaches. This technique requires a numerical implementation of the optical Fourier transform. We pay special attention to adapt the correlation filter to this numerical implementation. One main goal of this work is to reduce the size of the filter in order to decrease the memory space required for real time applications. To fulfil this requirement, we code the reference images with 8 bits and study the effect of this coding on the performances of several composite filters (phase-only filter, binary phase-only filter). The saturation effect has for effect to decrease the performances of the correlator for making a decision when filters contain up to nine references. Further, an optimization is proposed based for an optimized segmented composite filter. Based on this approach, we present tests with different faces demonstrating that the above mentioned saturation effect is significantly reduced while minimizing the size of the learning data base.

Virtual screening filters for the design of type II p38 MAP kinase inhibitors: a fragment based library generation approach.

PubMed

Badrinarayan, Preethi; Sastry, G Narahari

2012-04-01

In this work, we introduce the development and application of a three-step scoring and filtering procedure for the design of type II p38 MAP kinase leads using allosteric fragments extracted from virtual screening hits. The design of the virtual screening filters is based on a thorough evaluation of docking methods, DFG-loop conformation, binding interactions and chemotype specificity of the 138 p38 MAP kinase inhibitors from Protein Data Bank bound to DFG-in and DFG-out conformations using Glide, GOLD and CDOCKER. A 40 ns molecular dynamics simulation with the apo, type I with DFG-in and type II with DFG-out forms was carried out to delineate the effects of structural variations on inhibitor binding. The designed docking-score and sub-structure filters were first tested on a dataset of 249 potent p38 MAP kinase inhibitors from seven diverse series and 18,842 kinase inhibitors from PDB, to gauge their capacity to discriminate between kinase and non-kinase inhibitors and likewise to selectively filter-in target-specific inhibitors. The designed filters were then applied in the virtual screening of a database of ten million (10⁷) compounds resulting in the identification of 100 hits. Based on their binding modes, 98 allosteric fragments were extracted from the hits and a fragment library was generated. New type II p38 MAP kinase leads were designed by tailoring the existing type I ATP site binders with allosteric fragments using a common urea linker. Target specific virtual screening filters can thus be easily developed for other kinases based on this strategy to retrieve target selective compounds. Copyright © 2012 Elsevier Inc. All rights reserved.

Design certification tests: High Pressure Oxygen Filter (HPOF) program. Summary report

NASA Technical Reports Server (NTRS)

Smith, I. D.

1976-01-01

Design and acceptance certification test procedures and results are presented for a high pressure oxygen filter developed to protect the sealing surfaces in emergency oxygen systems. Equipment specifications are included.

Solid state electro-optic color filter and iris

NASA Technical Reports Server (NTRS)

1975-01-01

A pair of solid state electro-optic filters (SSEF) in a binocular holder were designed and fabricated for evaluation of field sequential stereo TV applications. The electronic circuitry for use with the stereo goggles was designed and fabricated, requiring only an external video input. A polarizing screen suitable for attachment to various size TV monitors for use in conjunction with the stereo goggles was designed and fabricated. An improved engineering model 2 filter was fabricated using the bonded holder technique developed previously and integrated to a GCTA color TV camera. An engineering model color filter was fabricated and assembled using PLZT control elements. In addition, a ruggedized holder assembly was designed, fabricated and tested. This assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and also permits mounting and optical alignment of the associated polarizers.

Evaluation of beam delivery and ripple filter design for non-isocentric proton and carbon ion therapy.

PubMed

Grevillot, L; Stock, M; Vatnitsky, S

2015-10-21

This study aims at selecting and evaluating a ripple filter design compatible with non-isocentric proton and carbon ion scanning beam treatment delivery for a compact nozzle. The use of non-isocentric treatments when the patient is shifted as close as possible towards the nozzle exit allows for a reduction in the air gap and thus an improvement in the quality of scanning proton beam treatment delivery. Reducing the air gap is less important for scanning carbon ions, but ripple filters are still necessary for scanning carbon ion beams to reduce the number of energy steps required to deliver homogeneous SOBP. The proper selection of ripple filters also allows a reduction in the possible transverse and depth-dose inhomogeneities that could appear in non-isocentric conditions in particular. A thorough review of existing ripple filter designs over the past 16 years is performed and a design for non-isocentric treatment delivery is presented. A unique ripple filter quality index (QIRiFi) independent of the particle type and energy and representative of the ratio between energy modulation and induced scattering is proposed. The Bragg peak width evaluated at the 80% dose level (BPW80) is proposed to relate the energy modulation of the delivered Bragg peaks and the energy layer step size allowing the production of homogeneous SOBP. Gate/Geant4 Monte Carlo simulations have been validated for carbon ion and ripple filter simulations based on measurements performed at CNAO and subsequently used for a detailed analysis of the proposed ripple filter design. A combination of two ripple filters in a series has been validated for non-isocentric delivery and did not show significant transverse and depth-dose inhomogeneities. Non-isocentric conditions allow a significant reduction in the spot size at the patient entrance (up to 350% and 200% for protons and carbon ions with range shifter, respectively), and therefore in the lateral penumbra in the patients.

Are special read alignment strategies necessary and cost-effective when handling sequencing reads from patient-derived tumor xenografts?

PubMed

Tso, Kai-Yuen; Lee, Sau Dan; Lo, Kwok-Wai; Yip, Kevin Y

2014-12-23

Patient-derived tumor xenografts in mice are widely used in cancer research and have become important in developing personalized therapies. When these xenografts are subject to DNA sequencing, the samples could contain various amounts of mouse DNA. It has been unclear how the mouse reads would affect data analyses. We conducted comprehensive simulations to compare three alignment strategies at different mutation rates, read lengths, sequencing error rates, human-mouse mixing ratios and sequenced regions. We also sequenced a nasopharyngeal carcinoma xenograft and a cell line to test how the strategies work on real data. We found the "filtering" and "combined reference" strategies performed better than aligning reads directly to human reference in terms of alignment and variant calling accuracies. The combined reference strategy was particularly good at reducing false negative variants calls without significantly increasing the false positive rate. In some scenarios the performance gain of these two special handling strategies was too small for special handling to be cost-effective, but it was found crucial when false non-synonymous SNVs should be minimized, especially in exome sequencing. Our study systematically analyzes the effects of mouse contamination in the sequencing data of human-in-mouse xenografts. Our findings provide information for designing data analysis pipelines for these data.

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.

Design of tunable thermo-optic C-band filter based on coated silicon slab

NASA Astrophysics Data System (ADS)

Pinhas, Hadar; Malka, Dror; Danan, Yossef; Sinvani, Moshe; Zalevsky, Zeev

2018-03-01

Optical filters are required to have narrow band-pass filtering in the spectral C-band for applications such as signal tracking, sub-band filtering or noise suppression. These requirements lead to a variety of filters such as Mach-Zehnder interferometer inter-leaver in silica, which offer thermo-optic effect for optical switching, however, without proper thermal and optical efficiency. In this paper we propose tunable thermo-optic filtering device based on coated silicon slab resonator with increased Q-factor for the C-band optical switching. The device can be designed either for long range wavelength tuning of for short range with increased wavelength resolution. Theoretical examination of the thermal parameters affecting the filtering process is shown together with experimental results. Proper channel isolation with an extinction ratio of 20dBs is achieved with spectral bandpass width of 0.07nm.

Filter Leaf. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

ERIC Educational Resources Information Center

Wooley, John F.

In the operation of vacuum filters and belt filters, it is desirable to evaluate the performance of different types of filter media and conditioning processes. The filter leaf test, which is used to evaluate these items, is described. Designed for individuals who have completed National Pollutant Discharge Elimination System (NPDES) level 1…

Diatomite Type Filters for Swimming Pools. Standard No. 9, Revised October, 1966.

ERIC Educational Resources Information Center

National Sanitation Foundation, Ann Arbor, MI.

Pressure and vacuum diatomite type filters are covered in this standard. The filters herein described are intended to be designed and used specifically for swimming pool water filtration, both public and residential. Included are the basic components which are a necessary part of the diatomite type filter such as filter housing, element supports,…

Quick-Change Optical-Filter Holder

NASA Technical Reports Server (NTRS)

Leone, Peter

1988-01-01

Dark slide and interlock protect against ambient light. Quick-change filter holder contains interlocking mechanism preventing simultaneous removal of both dark slide and filter drawer. Designed for use with Band pass optical filters in 10 channels leading to photomultiplier tubes in water-vapor lidar/ozone instrument, mechanism can be modified to operate in other optical systems requiring optical change in filters.

Hyperconnectivity, Attribute-Space Connectivity and Path Openings: Theoretical Relationships

NASA Astrophysics Data System (ADS)

Wilkinson, Michael H. F.

In this paper the relationship of hyperconnected filters with path openings and attribute-space connected filters is studied. Using a recently developed axiomatic framework based on hyperconnectivity operators, which are the hyperconnected equivalents of connectivity openings, it is shown that path openings are a special case of hyperconnected area openings. The new axiomatics also yield insight into the relationship between hyperconnectivity and attribute-space connectivity. It is shown any hyperconnectivity is an attribute-space connectivity, but that the reverse is not true.

Horizontal Estimation and Information Fusion in Multitarget and Multisensor Environments

DTIC Science & Technology

1987-09-01

provided needed inspirations. Special thanks are due to Distinguished Professor G . J. Thaler, Professor R . Panholzer, Professor N. F. Schneidewind, and...Guidance McGraw Hill, pp. 338-340, 1964. 31. Battin, R . H., and Levine, G . M., A22lication of Kalman Filtering Techniaues in The Aoollo Program, in Theory...FL.. pp. 171 -175, Dec. 197 1. 43. Singer, R . A., Sea R . G ., and Housewright K. B., Derivation and Evaluation of Imoroved Tracking Filters for Use in

Low temperature properties of spin filter NbN/GdN/NbN Josephson junctions

NASA Astrophysics Data System (ADS)

Massarotti, D.; Caruso, R.; Pal, A.; Rotoli, G.; Longobardi, L.; Pepe, G. P.; Blamire, M. G.; Tafuri, F.

2017-02-01

A ferromagnetic Josephson junction (JJ) represents a special class of hybrid system where different ordered phases meet and generate novel physics. In this work we report on the transport measurements of underdamped ferromagnetic NbN/GdN/NbN JJs at low temperatures. In these junctions the ferromagnetic insulator gadolinium nitride barrier generates spin-filtering properties and a dominant second harmonic component in the current-phase relation. These features make spin filter junctions quite interesting also in terms of fundamental studies on phase dynamics and dissipation. We discuss the fingerprints of spin filter JJs, through complementary transport measurements, and their implications on the phase dynamics, through standard measurements of switching current distributions. NbN/GdN/NbN JJs, where spin filter properties can be controllably tuned along with the critical current density (Jc), turn to be a very relevant term of reference to understand phase dynamics and dissipation in an enlarged class of JJs, not necessarily falling in the standard tunnel limit characterized by low Jc values.

Genetically Engineered Microelectronic Infrared Filters

NASA Technical Reports Server (NTRS)

Cwik, Tom; Klimeck, Gerhard

1998-01-01

A genetic algorithm is used for design of infrared filters and in the understanding of the material structure of a resonant tunneling diode. These two components are examples of microdevices and nanodevices that can be numerically simulated using fundamental mathematical and physical models. Because the number of parameters that can be used in the design of one of these devices is large, and because experimental exploration of the design space is unfeasible, reliable software models integrated with global optimization methods are examined The genetic algorithm and engineering design codes have been implemented on massively parallel computers to exploit their high performance. Design results are presented for the infrared filter showing new and optimized device design. Results for nanodevices are presented in a companion paper at this workshop.

Design of surface acoustic wave filters for the multiplex transmission system of multilevel inverter circuits

NASA Astrophysics Data System (ADS)

Kubo, Keita; Kanai, Nanae; Kobayashi, Fumiya; Goka, Shigeyoshi; Wada, Keiji; Kakio, Shoji

2017-07-01

We designed surface acoustic wave (SAW) filters for a multiplex transmission system of multilevel inverter circuits, and applied them to a single-phase three-level inverter. To reduce the transmission delay time of the SAW filters, a four-channel SAW filter array was fabricated and its characteristics were measured. The delay time of the SAW filters was <350 ns, and the delay time difference was reduced to ≤184 ns, less than half that previously reported. The SAW filters withstood up to 990 V, which is sufficient for the inverters used in most domestic appliances. A single-phase three-level inverter with the fabricated SAW filters worked with a total delay time shorter than our target delay time of 2.5 µs. The delay time difference of the proposed system was 0.26 µs, which is sufficient for preventing the inverter circuit from short-circuiting. The SAW filters controlled a multilevel inverter system with simple signal wiring and high dielectric withstanding voltages.

Spectroscopic imaging using acousto-optic tunable filters

NASA Astrophysics Data System (ADS)

Bouhifd, Mounir; Whelan, Maurice

2007-07-01

We report on novel hyper-spectral imaging filter-modules based on acousto-optic tuneable filters (AOTF). The AOTF functions as a full-field tuneable bandpass filter which offers fast continuous or random access tuning with high filtering efficiency. Due to the diffractive nature of the device, the unfiltered zero-order and the filtered first-order images are geometrically separated. The modules developed exploit this feature to simultaneously route both the transmitted white-light image and the filtered fluorescence image to two separate cameras. Incorporation of prisms in the optical paths and careful design of the relay optics in the filter module have overcome a number of aberrations inherent to imaging through AOTFs, leading to excellent spatial resolution. A number of practical uses of this technique, both for in vivo auto-fluorescence endoscopy and in vitro fluorescence microscopy were demonstrated. We describe the operational principle and design of recently improved prototype instruments for fluorescence-based diagnostics and demonstrate their performance by presenting challenging hyper-spectral fluorescence imaging applications.

Coplanar Waveguide Radial Line Double Stub and Application to Filter Circuits

NASA Technical Reports Server (NTRS)

Simons, R. N.; Taub, S. R.

1993-01-01

Coplanar waveguide (CPW) and grounded coplanar waveguide (GCPW) radial line double stub resonators are experimentally characterized with respect to stub radius and sector angle. A simple closed-form design equation, which predicts the resonance radius of the stub, is presented. Use of a double stub resonator as a lowpass filter or as a harmonic suppression filter is demonstrated, and design rules are given.

A reflective-type, quasi-optical metasurface filter

NASA Astrophysics Data System (ADS)

Sima, Boyu; Momeni Hasan Abadi, Seyed Mohamad Amin; Behdad, Nader

2017-08-01

We introduce a new technique for designing quasi-optical, reflective-type spatial filters. The proposed filter is a reflective metasurface with a one dimensional, frequency-dependent phase gradient along the aperture. By careful design of each unit cell of the metasurface, the phase shift gradient provided by the adjacent unit cells can be engineered to steer the beam towards a desired, anomalous reflection direction over the passband region of the filter. Outside of that range, the phase shift gradient required to produce the anomalous reflection is not present and hence, the wave is reflected towards the specular reflection direction. This way, the metasurface acts as a reflective filter in a quasi-optical system where the detector is placed along the direction of anomalous reflection. The spectral selectivity of this filter is determined by the frequency dispersion of the metasurface's phase response. Based on this principle, a prototype of the proposed metasurface filter, which operates at 10 GHz and has a bandwidth of 3%, is designed. The device is modeled using a combination of theoretical analysis using the phased-array theory and full-wave electromagnetic simulations. A prototype of this device is also fabricated and characterized using a free-space measurement system. Experimental results agree well with the simulations.

Efficient and Accurate Optimal Linear Phase FIR Filter Design Using Opposition-Based Harmony Search Algorithm

PubMed Central

Saha, S. K.; Dutta, R.; Choudhury, R.; Kar, R.; Mandal, D.; Ghoshal, S. P.

2013-01-01

In this paper, opposition-based harmony search has been applied for the optimal design of linear phase FIR filters. RGA, PSO, and DE have also been adopted for the sake of comparison. The original harmony search algorithm is chosen as the parent one, and opposition-based approach is applied. During the initialization, randomly generated population of solutions is chosen, opposite solutions are also considered, and the fitter one is selected as a priori guess. In harmony memory, each such solution passes through memory consideration rule, pitch adjustment rule, and then opposition-based reinitialization generation jumping, which gives the optimum result corresponding to the least error fitness in multidimensional search space of FIR filter design. Incorporation of different control parameters in the basic HS algorithm results in the balancing of exploration and exploitation of search space. Low pass, high pass, band pass, and band stop FIR filters are designed with the proposed OHS and other aforementioned algorithms individually for comparative optimization performance. A comparison of simulation results reveals the optimization efficacy of the OHS over the other optimization techniques for the solution of the multimodal, nondifferentiable, nonlinear, and constrained FIR filter design problems. PMID:23844390

Efficient and accurate optimal linear phase FIR filter design using opposition-based harmony search algorithm.

PubMed

Saha, S K; Dutta, R; Choudhury, R; Kar, R; Mandal, D; Ghoshal, S P

2013-01-01

In this paper, opposition-based harmony search has been applied for the optimal design of linear phase FIR filters. RGA, PSO, and DE have also been adopted for the sake of comparison. The original harmony search algorithm is chosen as the parent one, and opposition-based approach is applied. During the initialization, randomly generated population of solutions is chosen, opposite solutions are also considered, and the fitter one is selected as a priori guess. In harmony memory, each such solution passes through memory consideration rule, pitch adjustment rule, and then opposition-based reinitialization generation jumping, which gives the optimum result corresponding to the least error fitness in multidimensional search space of FIR filter design. Incorporation of different control parameters in the basic HS algorithm results in the balancing of exploration and exploitation of search space. Low pass, high pass, band pass, and band stop FIR filters are designed with the proposed OHS and other aforementioned algorithms individually for comparative optimization performance. A comparison of simulation results reveals the optimization efficacy of the OHS over the other optimization techniques for the solution of the multimodal, nondifferentiable, nonlinear, and constrained FIR filter design problems.

Optimal Design of Passive Power Filters Based on Pseudo-parallel Genetic Algorithm

NASA Astrophysics Data System (ADS)

Li, Pei; Li, Hongbo; Gao, Nannan; Niu, Lin; Guo, Liangfeng; Pei, Ying; Zhang, Yanyan; Xu, Minmin; Chen, Kerui

2017-05-01

The economic costs together with filter efficiency are taken as targets to optimize the parameter of passive filter. Furthermore, the method of combining pseudo-parallel genetic algorithm with adaptive genetic algorithm is adopted in this paper. In the early stages pseudo-parallel genetic algorithm is introduced to increase the population diversity, and adaptive genetic algorithm is used in the late stages to reduce the workload. At the same time, the migration rate of pseudo-parallel genetic algorithm is improved to change with population diversity adaptively. Simulation results show that the filter designed by the proposed method has better filtering effect with lower economic cost, and can be used in engineering.

Rugate filter for light-trapping in solar cells.

PubMed

Fahr, Stephan; Ulbrich, Carolin; Kirchartz, Thomas; Rau, Uwe; Rockstuhl, Carsten; Lederer, Falk

2008-06-23

We suggest a design for a coating that could be applied on top of any solar cell having at least one diffusing surface. This coating acts as an angle and wavelength selective filter, which increases the average path length and absorptance at long wavelengths without altering the solar cell performance at short wavelengths. The filter design is based on a continuous variation of the refractive index in order to minimize undesired reflection losses. Numerical procedures are used to optimize the filter for a 10 microm thick monocrystalline silicon solar cell, which lifts the efficiency above the Auger limit for unconcentrated illumination. The feasibility to fabricate such filters is also discussed, considering a finite available refractive index range.

Investigation of Dual-Mode Microstrip Bandpass Filter Based on SIR Technique

PubMed Central

Mezaal, Yaqeen S.; Ali, Jawad K.

2016-01-01

In this paper, a new bandpass filter design has been presented using simple topology of stepped impedance square loop resonator. The proposed bandpass filter has been simulated and fabricated using a substrate with an insulation constant of 10.8, thickness of 1.27mm and loss tangent of 0.0023 at center frequency of 5.8 GHz. The simulation results have been evaluated using Sonnet simulator that is extensively adopted in microwave analysis and implementation. The output frequency results demonstrated that the proposed filter has high-quality frequency responses in addition to isolated second harmonic frequency. Besides, this filter has very small surface area and perceptible narrow band response features that represent the conditions of recent wireless communication systems. Various filter specifications have been compared with different magnitudes of perturbation element dimension. Furthermore, phase scattering response and current intensity distribution of the proposed filter have been discussed. The simulated and experimental results are well-matched. Lastly, the features of the proposed filter have been compared with other designed microstrip filters in the literature. PMID:27798675

Silica dust exposure: Effect of filter size to compliance determination

NASA Astrophysics Data System (ADS)

Amran, Suhaily; Latif, Mohd Talib; Khan, Md Firoz; Leman, Abdul Mutalib; Goh, Eric; Jaafar, Shoffian Amin

2016-11-01

Monitoring of respirable dust was performed using a set of integrated sampling system consisting of sampling pump attached with filter media and separating device such as cyclone or special cassette. Based on selected method, filter sizes are either 25 mm or 37 mm poly vinyl chloride (PVC) filter. The aim of this study was to compare performance of two types of filter during personal respirable dust sampling for silica dust under field condition. The comparison strategy focused on the final compliance judgment based on both dataset. Eight hour parallel sampling of personal respirable dust exposure was performed among 30 crusher operators at six quarries. Each crusher operator was attached with parallel set of integrated sampling train containing either 25 mm or 37 mm PVC filter. Each set consisted of standard flow SKC sampler, attached with SKC GS3 cyclone and 2 pieces cassette loaded with 5.0 µm of PVC filter. Samples were analyzed by gravimetric technique. Personal respirable dust exposure between the two types of filters indicated significant positive correlation (p < 0.05) with moderate relationship (r2 = 0.6431). Personal exposure based on 25 mm PVC filter indicated 0.1% non-compliance to overall data while 37 mm PVC filter indicated similar findings at 0.4 %. Both data showed similar arithmetic mean(AM) and geometric mean(GM). In overall we concluded that personal respirable dust exposure either based on 25mm or 37mm PVC filter will give similar compliance determination. Both filters are reliable to be used in respirable dust monitoring for silica dust related exposure.

WE-F-16A-02: Design, Fabrication, and Validation of a 3D-Printed Proton Filter for Range Spreading

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

Remmes, N; Courneyea, L; Corner, S

2014-06-15

Purpose: To design, fabricate and test a 3D-printed filter for proton range spreading in scanned proton beams. The narrow Bragg peak in lower-energy synchrotron-based scanned proton beams can result in longer treatment times for shallow targets due to energy switching time and plan quality degradation due to minimum monitor unit limitations. A filter with variable thicknesses patterned on the same scale as the beam's lateral spot size will widen the Bragg peak. Methods: The filter consists of pyramids dimensioned to have a Gaussian distribution in thickness. The pyramids are 2.5mm wide at the base, 0.6 mm wide at the peak,more » 5mm tall, and are repeated in a 2.5mm pseudo-hexagonal lattice. Monte Carlo simulations of the filter in a proton beam were run using TOPAS to assess the change in depth profiles and lateral beam profiles. The prototypes were constrained to a 2.5cm diameter disk to allow for micro-CT imaging of promising prototypes. Three different 3D printers were tested. Depth-doses with and without the prototype filter were then measured in a ~70MeV proton beam using a multilayer ion chamber. Results: The simulation results were consistent with design expectations. Prototypes printed on one printer were clearly unacceptable on visual inspection. Prototypes on a second printer looked acceptable, but the micro-CT image showed unacceptable voids within the pyramids. Prototypes from the third printer appeared acceptable visually and on micro-CT imaging. Depth dose scans using the prototype from the third printer were consistent with simulation results. Bragg peak width increased by about 3x. Conclusions: A prototype 3D printer pyramid filter for range spreading was successfully designed, fabricated and tested. The filter has greater design flexibility and lower prototyping and production costs compared to traditional ridge filters. Printer and material selection played a large role in the successful development of the filter.« less

Kalman Filter Tracking on Parallel Architectures

NASA Astrophysics Data System (ADS)

Cerati, Giuseppe; Elmer, Peter; Lantz, Steven; McDermott, Kevin; Riley, Dan; Tadel, Matevž; Wittich, Peter; Würthwein, Frank; Yagil, Avi

2015-12-01

Power density constraints are limiting the performance improvements of modern CPUs. To address this we have seen the introduction of lower-power, multi-core processors, but the future will be even more exciting. In order to stay within the power density limits but still obtain Moore's Law performance/price gains, it will be necessary to parallelize algorithms to exploit larger numbers of lightweight cores and specialized functions like large vector units. Example technologies today include Intel's Xeon Phi and GPGPUs. Track finding and fitting is one of the most computationally challenging problems for event reconstruction in particle physics. At the High Luminosity LHC, for example, this will be by far the dominant problem. The need for greater parallelism has driven investigations of very different track finding techniques including Cellular Automata or returning to Hough Transform. The most common track finding techniques in use today are however those based on the Kalman Filter [2]. Significant experience has been accumulated with these techniques on real tracking detector systems, both in the trigger and offline. They are known to provide high physics performance, are robust and are exactly those being used today for the design of the tracking system for HL-LHC. Our previous investigations showed that, using optimized data structures, track fitting with Kalman Filter can achieve large speedup both with Intel Xeon and Xeon Phi. We report here our further progress towards an end-to-end track reconstruction algorithm fully exploiting vectorization and parallelization techniques in a realistic simulation setup.

Orbital angular momentum mode groups multiplexing transmission over 2.6-km conventional multi-mode fiber.

PubMed

Zhu, Long; Wang, Andong; Chen, Shi; Liu, Jun; Mo, Qi; Du, Cheng; Wang, Jian

2017-10-16

Twisted light carrying orbital angular momentum (OAM) is a special kind of structured light that has a helical phase front, a phase singularity, and a doughnut intensity profile. Beyond widespread developments in manipulation, microscopy, metrology, astronomy, nonlinear and quantum optics, OAM-carrying twisted light has seen emerging application of optical communications in free space and specially designed fibers. Instead of specialty fibers, here we show the direct use of a conventional graded-index multi-mode fiber (MMF) for OAM communications. By exploiting fiber-compatible mode exciting and filtering elements, we excite the first four OAM mode groups in an MMF. We demonstrate 2.6-km MMF transmission using four data-carrying OAM mode groups (OAM 0,1 , OAM +1,1 /OAM -1,1 , OAM +2,1 , OAM +3,1 ). Moreover, we demonstrate two data-carrying OAM mode groups multiplexing transmission over the 2.6-km MMF with low-level crosstalk free of multiple-input multiple-output digital signal processing (MIMO-DSP). The demonstrations may open up new perspectives to fiber-based OAM communication/non-communication applications using already existing conventional fibers.

Design of a robust thin-film interference filter for erbium-doped fiber amplifier gain equalization

NASA Astrophysics Data System (ADS)

Verly, Pierre G.

2002-06-01

Gain-flattening filters (GFFs) are key wavelength division multiplexing components in fiber-optics telecommunications. Challenging issues in the design of thin-film GFFs were recently the subject of a contest organized at the 2001 Conference on Optical Interference Coatings. The interest and main difficulty of the proposed problem was to minimize the sensitivity of a GFF to simulated fabrication errors. A high-yield solution and its design philosophy are described. The approach used to control the filter robustness is explained and illustrated by numerical results.

Design of a robust thin-film interference filter for erbium-doped fiber amplifier gain equalization.

PubMed

Verly, Pierre G

2002-06-01

Gain-flattening filters (GFFs) are key wavelength division multiplexing components in fiber-optics telecommunications. Challenging issues in the design of thin-film GFFs were recently the subject of a contest organized at the 2001 Conference on Optical Interference Coatings. The interest and main difficulty of the proposed problem was to minimize the sensitivity of a GFF to simulated fabrication errors. A high-yield solution and its design philosophy are described. The approach used to control the filter robustness is explained and illustrated by numerical results.

Computational tools for multi-linked flexible structures

NASA Technical Reports Server (NTRS)

Lee, Gordon K. F.; Brubaker, Thomas A.; Shults, James R.

1990-01-01

A software module which designs and tests controllers and filters in Kalman Estimator form, based on a polynomial state-space model is discussed. The user-friendly program employs an interactive graphics approach to simplify the design process. A variety of input methods are provided to test the effectiveness of the estimator. Utilities are provided which address important issues in filter design such as graphical analysis, statistical analysis, and calculation time. The program also provides the user with the ability to save filter parameters, inputs, and outputs for future use.

Hyperspectral Imaging Using Flexible Endoscopy for Laryngeal Cancer Detection

PubMed Central

Regeling, Bianca; Thies, Boris; Gerstner, Andreas O. H.; Westermann, Stephan; Müller, Nina A.; Bendix, Jörg; Laffers, Wiebke

2016-01-01

Hyperspectral imaging (HSI) is increasingly gaining acceptance in the medical field. Up until now, HSI has been used in conjunction with rigid endoscopy to detect cancer in vivo. The logical next step is to pair HSI with flexible endoscopy, since it improves access to hard-to-reach areas. While the flexible endoscope’s fiber optic cables provide the advantage of flexibility, they also introduce an interfering honeycomb-like pattern onto images. Due to the substantial impact this pattern has on locating cancerous tissue, it must be removed before the HS data can be further processed. Thereby, the loss of information is to minimize avoiding the suppression of small-area variations of pixel values. We have developed a system that uses flexible endoscopy to record HS cubes of the larynx and designed a special filtering technique to remove the honeycomb-like pattern with minimal loss of information. We have confirmed its feasibility by comparing it to conventional filtering techniques using an objective metric and by applying unsupervised and supervised classifications to raw and pre-processed HS cubes. Compared to conventional techniques, our method successfully removes the honeycomb-like pattern and considerably improves classification performance, while preserving image details. PMID:27529255

Hyperspectral Imaging Using Flexible Endoscopy for Laryngeal Cancer Detection.

PubMed

Regeling, Bianca; Thies, Boris; Gerstner, Andreas O H; Westermann, Stephan; Müller, Nina A; Bendix, Jörg; Laffers, Wiebke

2016-08-13

Hyperspectral imaging (HSI) is increasingly gaining acceptance in the medical field. Up until now, HSI has been used in conjunction with rigid endoscopy to detect cancer in vivo. The logical next step is to pair HSI with flexible endoscopy, since it improves access to hard-to-reach areas. While the flexible endoscope's fiber optic cables provide the advantage of flexibility, they also introduce an interfering honeycomb-like pattern onto images. Due to the substantial impact this pattern has on locating cancerous tissue, it must be removed before the HS data can be further processed. Thereby, the loss of information is to minimize avoiding the suppression of small-area variations of pixel values. We have developed a system that uses flexible endoscopy to record HS cubes of the larynx and designed a special filtering technique to remove the honeycomb-like pattern with minimal loss of information. We have confirmed its feasibility by comparing it to conventional filtering techniques using an objective metric and by applying unsupervised and supervised classifications to raw and pre-processed HS cubes. Compared to conventional techniques, our method successfully removes the honeycomb-like pattern and considerably improves classification performance, while preserving image details.

CBR/TIC Filter Design and Evaluation

DTIC Science & Technology

2006-12-29

CBR/TIC Filters Aged CK Filter Life Predicitions.................................................................. 29 Figure 30. CBR/TIC Filters...potting adhesive. Neoprene rubber face gaskets are adhered to each end of the particulate filter for airtight sealing. Figure 16. CBR/TIC HEPA...attached with adhesive to the bottom end cover and is spaced by the compression pads on the top end. EPDM foam compression pads are placed on top

Different depth intermittent sand filters for laboratory treatment of synthetic wastewater with concentrations close to measured septic tank effluent.

PubMed

Rodgers, M; Walsh, G; Healy, M G

2011-01-01

The objective of this study was to apply hydraulic and chemical oxygen demand (COD) loading rates at the upper limits of the design criteria for buried sand filters to test the sand filter depth design criteria. Over a 274-day study duration, synthetic effluent with a strength of domestic wastewater was intermittently dosed onto two sand filters of 0.2 m diameter, with depths of 0.3 and 0.4 m. Hydraulic and organic carbon loading rates of 105 L m(-2) d(-1) and 40 g COD m(-2) d(-1), respectively, were applied to the filters. The filters did not clog and had good effluent removal capabilities for 274 and 190 days, respectively. However, the 0.3 m-deep filter did experience a reduced performance towards the end of the study period. In the 0.3 and 0.4 m-deep filters, the effluent COD and SS concentrations were less than 86 and 31 mg L(-1), respectively, and nitrification was nearly complete in both these columns. Ortho-phosphorus (PO(4)-P) removal in fine sand and laterite 'upflow' filters, receiving effluent from the 0.3 m-deep filter, was 10% and 44%, respectively.

A robust spatial filtering technique for multisource localization and geoacoustic inversion.

PubMed

Stotts, S A

2005-07-01

Geoacoustic inversion and source localization using beamformed data from a ship of opportunity has been demonstrated with a bottom-mounted array. An alternative approach, which lies within a class referred to as spatial filtering, transforms element level data into beam data, applies a bearing filter, and transforms back to element level data prior to performing inversions. Automation of this filtering approach is facilitated for broadband applications by restricting the inverse transform to the degrees of freedom of the array, i.e., the effective number of elements, for frequencies near or below the design frequency. A procedure is described for nonuniformly spaced elements that guarantees filter stability well above the design frequency. Monitoring energy conservation with respect to filter output confirms filter stability. Filter performance with both uniformly spaced and nonuniformly spaced array elements is discussed. Vertical (range and depth) and horizontal (range and bearing) ambiguity surfaces are constructed to examine filter performance. Examples that demonstrate this filtering technique with both synthetic data and real data are presented along with comparisons to inversion results using beamformed data. Examinations of cost functions calculated within a simulated annealing algorithm reveal the efficacy of the approach.

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

Destriping of Landsat MSS images by filtering techniques

USGS Publications Warehouse

Pan, Jeng-Jong; Chang, Chein-I

1992-01-01

: The removal of striping noise encountered in the Landsat Multispectral Scanner (MSS) images can be generally done by using frequency filtering techniques. Frequency do~ain filteri~g has, how~ver, se,:era~ prob~ems~ such as storage limitation of data required for fast Fourier transforms, nngmg artl~acts appe~nng at hlgh-mt,enslty.dlscontinuities, and edge effects between adjacent filtered data sets. One way for clrcu~,,:entmg the above difficulties IS, to design a spatial filter to convolve with the images. Because it is known that the,stnpmg a.lways appears at frequencies of 1/6, 1/3, and 1/2 cycles per line, it is possible to design a simple one-dimensIOnal spat~a~ fll,ter to take advantage of this a priori knowledge to cope with the above problems. The desired filter is the type of ~mlte Impuls~ response which can be designed by a linear programming and Remez's exchange algorithm coupled ~lth an adaptIve tec,hmque. In addition, a four-step spatial filtering technique with an appropriate adaptive approach IS also presented which may be particularly useful for geometrically rectified MSS images.

A Game Theoretic Fault Detection Filter

NASA Technical Reports Server (NTRS)

Chung, Walter H.; Speyer, Jason L.

1995-01-01

The fault detection process is modelled as a disturbance attenuation problem. The solution to this problem is found via differential game theory, leading to an H(sub infinity) filter which bounds the transmission of all exogenous signals save the fault to be detected. For a general class of linear systems which includes some time-varying systems, it is shown that this transmission bound can be taken to zero by simultaneously bringing the sensor noise weighting to zero. Thus, in the limit, a complete transmission block can he achieved, making the game filter into a fault detection filter. When we specialize this result to time-invariant system, it is found that the detection filter attained in the limit is identical to the well known Beard-Jones Fault Detection Filter. That is, all fault inputs other than the one to be detected (the "nuisance faults") are restricted to an invariant subspace which is unobservable to a projection on the output. For time-invariant systems, it is also shown that in the limit, the order of the state-space and the game filter can be reduced by factoring out the invariant subspace. The result is a lower dimensional filter which can observe only the fault to be detected. A reduced-order filter can also he generated for time-varying systems, though the computational overhead may be intensive. An example given at the end of the paper demonstrates the effectiveness of the filter as a tool for fault detection and identification.

Ultraviolet filters in stomatopod crustaceans: diversity, ecology and evolution.

PubMed

Bok, Michael J; Porter, Megan L; Cronin, Thomas W

2015-07-01

Stomatopod crustaceans employ unique ultraviolet (UV) optical filters in order to tune the spectral sensitivities of their UV-sensitive photoreceptors. In the stomatopod species Neogonodactylus oerstedii, we previously found four filter types, produced by five distinct mycosporine-like amino acid pigments in the crystalline cones of their specialized midband ommatidial facets. This UV-spectral tuning array produces receptors with at least six distinct spectral sensitivities, despite expressing only two visual pigments. Here, we present a broad survey of these UV filters across the stomatopod order, examining their spectral absorption properties in 21 species from seven families in four superfamilies. We found that UV filters are present in three of the four superfamilies, and evolutionary character reconstruction implies that at least one class of UV filter was present in the ancestor of all modern stomatopods. Additionally, postlarval stomatopods were observed to produce the UV filters simultaneously alongside development of the adult eye. The absorbance properties of the filters are consistent within a species; however, between species we found a great deal of diversity, both in the number of filters and in their spectral absorbance characteristics. This diversity correlates with the habitat depth ranges of these species, suggesting that species living in shallow, UV-rich environments may tune their UV spectral sensitivities more aggressively. We also found additional, previously unrecognized UV filter types in the crystalline cones of the peripheral eye regions of some species, indicating the possibility for even greater stomatopod visual complexity than previously thought. © 2015. Published by The Company of Biologists Ltd.

Development of a filter to prevent infections with spore-forming bacteria in injecting drug users.

PubMed

Alhusein, Nour; Scott, Jenny; Kasprzyk-Hordern, Barbara; Bolhuis, Albert

2016-12-01

In heroin injectors, there have been a number of outbreaks caused by spore-forming bacteria, causing serious infections such as anthrax or botulism. These are, most likely, caused by injecting contaminated heroin, and our aim was to develop a filter that efficiently removes these bacteria and is also likely to be acceptable for use by people who inject drugs (i.e. quick, simple and not spoil the hit). A prototype filter was designed and different filter membranes were tested to assess the volume of liquid retained, filtration time and efficiency of the filter at removing bacterial spores. Binding of active ingredients of heroin to different types of membrane filters was determined using a highly sensitive analytical chemistry technique. Heroin samples that were tested contained up to 580 bacteria per gramme, with the majority being Bacillus spp., which are spore-forming soil bacteria. To remove these bacteria, a prototype filter was designed to fit insulin-type syringes, which are commonly used by people who inject drugs (PWIDs). Efficient filtration of heroin samples was achieved by combining a prefilter to remove particles and a 0.22 μm filter to remove bacterial spores. The most suitable membrane was polyethersulfone (PES). This membrane had the shortest filtration time while efficiently removing bacterial spores. No or negligible amounts of active ingredients in heroin were retained by the PES membrane. This study successfully produced a prototype filter designed to filter bacterial spores from heroin samples. Scaled up production could produce an effective harm reduction tool, especially during outbreaks such as occurred in Europe in 2009/10 and 2012.

Sequential Blood Filtration for Extracorporeal Circulation: Initial Results from a Proof-of-Concept Prototype.

PubMed

Herbst, Daniel P

2014-09-01

Micropore filters are used during extracorporeal circulation to prevent gaseous and solid particles from entering the patient's systemic circulation. Although these devices improve patient safety, limitations in current designs have prompted the development of a new concept in micropore filtration. A prototype of the new design was made using 40-μm filter screens and compared against four commercially available filters for performance in pressure loss and gross air handling. Pre- and postfilter bubble counts for 5- and 10-mL bolus injections in an ex vivo test circuit were recorded using a Doppler ultrasound bubble counter. Statistical analysis of results for bubble volume reduction between test filters was performed with one-way repeated-measures analysis of variance using Bonferroni post hoc tests. Changes in filter performance with changes in microbubble load were also assessed with dependent t tests using the 5- and 10-mL bolus injections as the paired sample for each filter. Significance was set at p < .05. All filters in the test group were comparable in pressure loss performance, showing a range of 26-33 mmHg at a flow rate of 6 L/min. In gross air-handling studies, the prototype showed improved bubble volume reduction, reaching statistical significance with three of the four commercial filters. All test filters showed decreased performance in bubble volume reduction when the microbubble load was increased. Findings from this research support the underpinning theories of a sequential arterial-line filter design and suggest that improvements in microbubble filtration may be possible using this technique.

Sequential Blood Filtration for Extracorporeal Circulation: Initial Results from a Proof-of-Concept Prototype

PubMed Central

Herbst, Daniel P.

2014-01-01

Abstract: Micropore filters are used during extracorporeal circulation to prevent gaseous and solid particles from entering the patient’s systemic circulation. Although these devices improve patient safety, limitations in current designs have prompted the development of a new concept in micropore filtration. A prototype of the new design was made using 40-μm filter screens and compared against four commercially available filters for performance in pressure loss and gross air handling. Pre- and postfilter bubble counts for 5- and 10-mL bolus injections in an ex vivo test circuit were recorded using a Doppler ultrasound bubble counter. Statistical analysis of results for bubble volume reduction between test filters was performed with one-way repeated-measures analysis of variance using Bonferroni post hoc tests. Changes in filter performance with changes in microbubble load were also assessed with dependent t tests using the 5- and 10-mL bolus injections as the paired sample for each filter. Significance was set at p < .05. All filters in the test group were comparable in pressure loss performance, showing a range of 26–33 mmHg at a flow rate of 6 L/min. In gross air-handling studies, the prototype showed improved bubble volume reduction, reaching statistical significance with three of the four commercial filters. All test filters showed decreased performance in bubble volume reduction when the microbubble load was increased. Findings from this research support the underpinning theories of a sequential arterial-line filter design and suggest that improvements in microbubble filtration may be possible using this technique. PMID:26357790

Raman Laser Spectrometer internal Optical Head current status: opto-mechanical redesign to minimize the excitation laser trace

NASA Astrophysics Data System (ADS)

Sanz, Miguel; Ramos, Gonzalo; Moral, Andoni; Pérez, Carlos; Belenguer, Tomás; del Rosario Canchal, María; Zuluaga, Pablo; Rodriguez, Jose Antonio; Santiago, Amaia; Rull, Fernando; Instituto Nacional de Técnica Aeroespacial (INTA); Ingeniería de Sistemas para la Defesa de España S.A. (ISDEFE)

2016-10-01

Raman Laser Spectrometer (RLS) is the Pasteur Payload instruments of the ExoMars mission, within the ESA's Aurora Exploration Programme, that will perform for the first time in an out planetary mission Raman spectroscopy. RLS is composed by SPU (Spectrometer Unit), iOH (Internal Optical Head), and ICEU (Instrument Control and Excitation Unit). iOH focuses the excitation laser on the samples (excitation path), and collects the Raman emission from the sample (collection path, composed on collimation system and filtering system). The original design presented a high laser trace reaching to the detector, and although a certain level of laser trace was required for calibration purposes, the high level degrades the Signal to Noise Ratio confounding some Raman peaks.The investigation revealing that the laser trace was not properly filtered as well as the iOH opto-mechanical redesign are reported on. After the study of the Long Pass Filters Optical Density (OD) as a function of the filtering stage to the detector distance, a new set of filters (Notch filters) was decided to be evaluated. Finally, and in order to minimize the laser trace, a new collection path design (mainly consisting on that the collimation and filtering stages are now separated in two barrels, and on the kind of filters to be used) was required. Distance between filters and collimation stage first lens was increased, increasing the OD. With this new design and using two Notch filters, the laser trace was reduced to assumable values, as can be observed in the functional test comparison also reported on this paper.

The Application of the FDTD Method to Millimeter-Wave Filter Circuits Including the Design and Analysis of a Compact Coplanar

NASA Technical Reports Server (NTRS)

Oswald, J. E.; Siegel, P. H.

1994-01-01

The finite difference time domain (FDTD) method is applied to the analysis of microwave, millimeter-wave and submillimeter-wave filter circuits. In each case, the validity of this method is confirmed by comparison with measured data. In addition, the FDTD calculations are used to design a new ultra-thin coplanar-strip filter for feeding a THz planar-antenna mixer.

Low power adder based auditory filter architecture.

PubMed

Rahiman, P F Khaleelur; Jayanthi, V S

2014-01-01

Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT) based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%.

GaN-based metamaterial terahertz bandpass filter design: tunability and ultra-broad passband attainment.

PubMed

Khodaee, M; Banakermani, M; Baghban, H

2015-10-10

Engineering metamaterial-based devices such as terahertz bandpass filters (BPFs) play a definitive role in advancement of terahertz technology. In this article, we propose a design procedure to obtain a considerably broadband terahertz BPF at a normal incidence; it shows promising filtering characteristics, including a wide passband of ∼1.34  THz at a central frequency of 1.17 THz, a flat top in a broad band, and high transmission, compared to previous reports. Then, exploiting the voltage-dependent carrier density control in an AlGaN/GaN heterostructure with a Schottky gate configuration, we investigate the tuning of the transmission properties in a narrow-band terahertz filter. A combination of the ultra-wide, flat-top BPF in series with the tunable, narrow band filter designed in the current study offers the ability to tune the desired resonance frequency along with high out-of-band rejection and the suppression of unwanted resonances in a large spectral range. The proposed structure exhibits a frequency tunability of 103 GHz for a voltage change between -8 and 2 V, and a transmission amplitude change of ∼0.51. This scheme may open up a route for the improved design of terahertz filters and modulators.

Evolution of an Interfacial Crack on the Concrete Embankment Boundary

NASA Astrophysics Data System (ADS)

Smith, J.; Ezzedine, S. M.; Lomov, I.; Kanarska, Y.; Antoun, T.; Glascoe, L. G.; Hall, R. L.; Woodson, S. C.

2013-12-01

Failure of a dam can have subtle beginnings: a small crack or dislocation at the interface of the concrete dam and the surrounding embankment soil initiated by a seismic event, for example, can: a) result in creating gaps between the concrete dam and the lateral embankments; b) initiate internal erosion of embankment; and c) lead to a catastrophic failure of the dam. The dam may ';self-rehabilitate' if a properly designed granular filter is engineered around the embankment. Currently, the design criteria for such filters have only been based on experimental studies. We demonstrate the numerical prediction of filter effectiveness at the soil grain scale and relate it to the larger dam scale. Validated computer predictions highlight that a resilient (or durable) filter is consistent with the current design specifications for dam filters. These predictive simulations, unlike the design specifications, can be used to assess filter success or failure under different soil or loading conditions and can lead to meaningful estimates of the timing and nature of full-scale dam failure. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was sponsored by the Department of Homeland Security (DHS), Science and Technology Directorate, Homeland Security Advanced Research Projects Agency (HSARPA).

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 test IOP test data. Though the region of interest of the signals examined in the current study did not contain extremely high frequency content, it is possible that live-fire testing may produce shock waves with higher frequency content. While post-processing filtering can remove experimental artifacts, special care should be taken to minimize or eliminate the possibility of recording these artifacts in the first place.

Compressive spectral testbed imaging system based on thin-film color-patterned filter arrays.

PubMed

Rueda, Hoover; Arguello, Henry; Arce, Gonzalo R

2016-11-20

Compressive spectral imaging systems can reliably capture multispectral data using far fewer measurements than traditional scanning techniques. In this paper, a thin-film patterned filter array-based compressive spectral imager is demonstrated, including its optical design and implementation. The use of a patterned filter array entails a single-step three-dimensional spatial-spectral coding on the input data cube, which provides higher flexibility on the selection of voxels being multiplexed on the sensor. The patterned filter array is designed and fabricated with micrometer pitch size thin films, referred to as pixelated filters, with three different wavelengths. The performance of the system is evaluated in terms of references measured by a commercially available spectrometer and the visual quality of the reconstructed images. Different distributions of the pixelated filters, including random and optimized structures, are explored.

System-level analysis and design for RGB-NIR CMOS camera

NASA Astrophysics Data System (ADS)

Geelen, Bert; Spooren, Nick; Tack, Klaas; Lambrechts, Andy; Jayapala, Murali

2017-02-01

This paper presents system-level analysis of a sensor capable of simultaneously acquiring both standard absorption based RGB color channels (400-700nm, 75nm FWHM), as well as an additional NIR channel (central wavelength: 808 nm, FWHM: 30nm collimated light). Parallel acquisition of RGB and NIR info on the same CMOS image sensor is enabled by monolithic pixel-level integration of both a NIR pass thin film filter and NIR blocking filters for the RGB channels. This overcomes the need for a standard camera-level NIR blocking filter to remove the NIR leakage present in standard RGB absorption filters from 700-1000nm. Such a camera-level NIR blocking filter would inhibit the acquisition of the NIR channel on the same sensor. Thin film filters do not operate in isolation. Rather, their performance is influenced by the system context in which they operate. The spectral distribution of light arriving at the photo diode is shaped a.o. by the illumination spectral profile, optical component transmission characteristics and sensor quantum efficiency. For example, knowledge of a low quantum efficiency (QE) of the CMOS image sensor above 800nm may reduce the filter's blocking requirements and simplify the filter structure. Similarly, knowledge of the incoming light angularity as set by the objective lens' F/# and exit pupil location may be taken into account during the thin film's optimization. This paper demonstrates how knowledge of the application context can facilitate filter design and relax design trade-offs and presents experimental results.

Management of Fractured Inferior Vena Cava Filters: Outcomes by Fragment Location.

PubMed

Trerotola, Scott O; Stavropoulos, S William

2017-09-01

Purpose To inform the management of fractured inferior vena cava filters on the basis of results from a tertiary referral center specializing in complex filter retrieval. Materials and Methods This study had institutional review board approval and was HIPAA compliant. Retrospective analysis of all patients with fractured filters and/or filter fragments evaluated for removal in a complex filter removal program was performed. Removal was attempted when fragments were intravascular or immediately extravascular by using primarily endobronchial forceps for caval fragments and snares for cardiac and pulmonary fragments. Data collected included success rate and complications of filter and fragment removal, symptoms relating to the filter or fragment, techniques used for removal, and follow-up of retained fragments. Results Sixty-five patients (12 men, 53 women) of a total of 222 patients referred for complex retrieval had fractured filters. Of these patients, two had undergone filter removal elsewhere and had retained fragments. All 63 filters were removed successfully with forceps (n = 61), a cone (n = 1), or a snare (n = 1). There were 116 separate filter fragments; removal was attempted for 78 fragments. Removal was successful for 63 (81%) of 78 fragments and varied by location. All extravascular fragments except one were retained. In all, 63 (54%) of 116 fragments were removed percutaneously, rendering 34 (54%) of 63 patients fragment free. Five minor (7.7% [five of 65]) and four major (6.2% [four of 65]) complications occurred. Conclusion Intravascular filter fragments can be removed safely with success rates that vary according to location. Because extravascular fragments are not readily accessible for removal, many patients are not rendered fragment free. © RSNA, 2017 Online supplemental material is available for this article.

A microprocessor based anti-aliasing filter for a PCM system

NASA Technical Reports Server (NTRS)

Morrow, D. C.; Sandlin, D. R.

1984-01-01

Described is the design and evaluation of a microprocessor based digital filter. The filter was made to investigate the feasibility of a digital replacement for the analog pre-sampling filters used in telemetry systems at the NASA Ames-Dryden Flight Research Facility (DFRF). The digital filter will utilize an Intel 2920 Analog Signal Processor (ASP) chip. Testing includes measurements of: (1) the filter frequency response and, (2) the filter signal resolution. The evaluation of the digital filter was made on the basis of circuit size, projected environmental stability and filter resolution. The 2920 based digital filter was found to meet or exceed the pre-sampling filter specifications for limited signal resolution applications.

Acousto-optical tunable filter for combined wideband, spectral, and optical coherence microscopy.

PubMed

Machikhin, Alexander S; Pozhar, Vitold E; Viskovatykh, Alexander V; Burmak, Ludmila I

2015-09-01

A multimodal technique for inspection of microscopic objects by means of wideband optical microscopy, spectral microscopy, and optical coherence microscopy is described, implemented, and tested. The key feature is the spectral selection of light in the output arm of an interferometer with use of the specialized imaging acousto-optical tunable filter. In this filter, two interfering optical beams are diffracted via the same ultrasound wave without destruction of interference image structure. The basic requirements for the acousto-optical tunable filter are defined, and mathematical formulas for calculation of its parameters are derived. Theoretical estimation of the achievable accuracy of the 3D image reconstruction is presented and experimental proofs are given. It is demonstrated that spectral imaging can also be accompanied by measurement of the quantitative reflectance spectra. Examples of inspection of optically transparent and nontransparent samples demonstrate the applicability of the technique.

A Real-Time De-Noising Algorithm for E-Noses in a Wireless Sensor Network

PubMed Central

Qu, Jianfeng; Chai, Yi; Yang, Simon X.

2009-01-01

A wireless e-nose network system is developed for the special purpose of monitoring odorant gases and accurately estimating odor strength in and around livestock farms. This system is to simultaneously acquire accurate odor strength values remotely at various locations, where each node is an e-nose that includes four metal-oxide semiconductor (MOS) gas sensors. A modified Kalman filtering technique is proposed for collecting raw data and de-noising based on the output noise characteristics of those gas sensors. The measurement noise variance is obtained in real time by data analysis using the proposed slip windows average method. The optimal system noise variance of the filter is obtained by using the experiments data. The Kalman filter theory on how to acquire MOS gas sensors data is discussed. Simulation results demonstrate that the proposed method can adjust the Kalman filter parameters and significantly reduce the noise from the gas sensors. PMID:22399946

Multidimensional signaling via wavelet packets

NASA Astrophysics Data System (ADS)

Lindsey, Alan R.

1995-04-01

This work presents a generalized signaling strategy for orthogonally multiplexed communication. Wavelet packet modulation (WPM) employs the basis functions from an arbitrary pruning of a full dyadic tree structured filter bank as orthogonal pulse shapes for conventional QAM symbols. The multi-scale modulation (MSM) and M-band wavelet modulation (MWM) schemes which have been recently introduced are handled as special cases, with the added benefit of an entire library of potentially superior sets of basis functions. The figures of merit are derived and it is shown that the power spectral density is equivalent to that for QAM (in fact, QAM is another special case) and hence directly applicable in existing systems employing this standard modulation. Two key advantages of this method are increased flexibility in time-frequency partitioning and an efficient all-digital filter bank implementation, making the WPM scheme more robust to a larger set of interferences (both temporal and sinusoidal) and computationally attractive as well.

Geometrical pose and structural estimation from a single image for automatic inspection of filter components

NASA Astrophysics Data System (ADS)

Liu, Yonghuai; Rodrigues, Marcos A.

2000-03-01

This paper describes research on the application of machine vision techniques to a real time automatic inspection task of air filter components in a manufacturing line. A novel calibration algorithm is proposed based on a special camera setup where defective items would show a large calibration error. The algorithm makes full use of rigid constraints derived from the analysis of geometrical properties of reflected correspondence vectors which have been synthesized into a single coordinate frame and provides a closed form solution to the estimation of all parameters. For a comparative study of performance, we also developed another algorithm based on this special camera setup using epipolar geometry. A number of experiments using synthetic data have shown that the proposed algorithm is generally more accurate and robust than the epipolar geometry based algorithm and that the geometric properties of reflected correspondence vectors provide effective constraints to the calibration of rigid body transformations.

Three-dimensional seismic depth migration

NASA Astrophysics Data System (ADS)

Zhou, Hongbo

1998-12-01

One-pass 3-D modeling and migration for poststack seismic data may be implemented by replacing the traditional 45sp° one-way wave equation (a third-order partial differential equation) with a pair of second and first order partial differential equations. Except for an extra correction term, the resulting second order equation has a form similar to Claerbout's 15sp° one-way wave equation, which is known to have a nearly circular horizontal impulse response. In this approach, there is no need to compensate for splitting errors. Numerical tests on synthetic data show that this algorithm has the desirable attributes of being second-order in accuracy and economical to solve. A modification of the Crank-Nicholson implementation maintains stability. Absorbing boundary conditions play an important role in one-way wave extrapolations by reducing reflections at grid edges. Clayton and Engquist's 2-D absorbing boundary conditions for one-way wave extrapolation by depth-stepping in the frequency domain are extended to 3-D using paraxial approximations of the scalar wave equation. Internal consistency is retained by incorporating the interior extrapolation equation with the absorbing boundary conditions. Numerical schemes are designed to make the proposed absorbing boundary conditions both mathematically correct and efficient with negligible extra cost. Synthetic examples illustrate the effectiveness of the algorithm for extrapolation with the 3-D 45sp° one-way wave equation. Frequency-space domain Butterworth and Chebyshev dip filters are implemented. By regrouping the product terms in the filter transfer function into summations, a cascaded (serial) Butterworth dip filter can be made parallel. A parallel Chebyshev dip filter can be similarly obtained, and has the same form as the Butterworth filter; but has different coeffcients. One of the advantages of the Chebyshev filter is that it has a sharper transition zone than that of Butterworth filter of the same order. Both filters are incorporated into 3-D one-way frequency-space depth migration for evanescent energy removal and for phase compensation of splitting errors; a single filter achieves both goals. Synthetic examples illustrate the behavior of the parallel filters. For a given order of filter, the cost of the Butterworth and Chebyshev filters is the same. A Chebyshev filter is more effective for phase compensation than the Butterworth filter of the same order, at the expense of some wavenumber-dependent amplitude ripples. An analytical formula for geometrical spreading is derived for a horizontally layered transversely isotropic medium with a vertical symmetry axis. Under this expression, geometrical spreading can be determined only by the anisotropic parameters in the first layer, the traveltime derivatives, and source-receiver offset. An explicit, numerically feasible expression for geometrical spreading can be further obtained by considering some of the special cases of transverse isotropy, such as weak anisotropy or elliptic anisotropy. Therefore, with the techniques of non-hyerbolic moveout for transverse isotropic media, geometrical spreading can be calculated by using picked traveltimes of primary P-wave reflections without having to know the actual parameters in the deeper subsurface; no ray tracing is needed. Synthetic examples verify the algorithm and show that it is numerically feasible for calculation of geometrical spreading.

One-meter Schmidt telescope of the Byurakan Astrophysical Observatory: New capabilities

NASA Astrophysics Data System (ADS)

Dodonov, S. N.; Kotov, S. S.; Movsesyan, T. A.; Gevorkyan, M.

2017-10-01

In 2013-2015 the Laboratory of spectroscopy and photometry of extragalactic objects (LS-PEO) of the Special Astrophysical Observatory together with Armenian specialists upgraded the 1-m Schmidt telescope of the Byurakan Astrophysical Observatory of the National Academy of Sciences of Armenia. We completely redesigned the control system of the telescope: we replaced the actuating mechanisms, developed telescope control software, and made the guiding system. We reworked and prepared a 4k × 4k Apogee (USA) liquid-cooled CCD with RON 11.1 e -, a pixel size of 0.″868, and field of view of about 1□°, and in October 2015 mounted it in the focus of the telescope. The detector is equipped with a turret bearing 20 intermediate-band filters ( FWHM = 250 Å) uniformly covering the 4000-9000 Å wavelength range, five broadband filters ( u, g, r, i, z SDSS), and three narrow-band filters (5000 Å, 6560 Å and 6760 Å, FWHM = 100 Å). During the first year of test operation of the 1-m telescope we performed pilot observations within the framework of three programs: search for young stellar objects, AGNevolution, and stellar composition of galaxy disks.We confirmed the possibility of efficiently selecting of young objects using observations performed in narrow-band H α and [SII] filters and the intermediate-band 7500 Å filter. Three-hours long exposures with SDSS g-, r-, and i-band filters allow us to reach the surface brightness level of 28m/□″ when investigating the stellar content of galaxy disks for a sample of nine galaxies. We used observations performed with the 1-m telescope in five broadband (SDSS u, g, r, i, and z) and 15 intermediate-band filters (4000-7500 Å) to construct a sample of quasar candidates with 0.5 < z < 5 (330 objects) in about one-sq. degree SA68 field complete down to R AB = 23m. Spectroscopic observations of 29 objects (19.m5 < R < 22m) carried out at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences confirmed the quasar nature of 28 objects.

A VHDL Core for Intrinsic Evolution of Discrete Time Filters with Signal Feedback

NASA Technical Reports Server (NTRS)

Gwaltney, David A.; Dutton, Kenneth

2005-01-01

The design of an Evolvable Machine VHDL Core is presented, representing a discrete-time processing structure capable of supporting control system applications. This VHDL Core is implemented in an FPGA and is interfaced with an evolutionary algorithm implemented in firmware on a Digital Signal Processor (DSP) to create an evolvable system platform. The salient features of this architecture are presented. The capability to implement IIR filter structures is presented along with the results of the intrinsic evolution of a filter. The robustness of the evolved filter design is tested and its unique characteristics are described.

Analysis and design of planar waveguide elements for use in filters and sensors

NASA Astrophysics Data System (ADS)

Chen, Guangzhou

In this dissertation we present both theoretical analysis and practical design considerations for planar optical waveguide devices. The analysis takes into account both transverse dimensions of the waveguides and is based on supermode theory combined with the resonance method for the determination of the propagation constants and field profiles of the supermodes. An improved accuracy has been achieved by including corrections due to the fields in the corner regions of the waveguides using perturbation theory. We analyze in detail two particular devices, an optical filter/combiner and an optical sensor. An optical wavelength filter/combiner is a common element in an integrated optical circuit. A new "bend free" filter/combiner is proposed and analyzed. The new wavelength filter consists of only straight parallel channels, which considerably simplify both the analysis and fabrication of the device. We show in detail how the operation of the device depends upon each of the design parameters. The intrinsic power loss in the proposed filter/combiner is minimized. The optical sensor is another important device and the sensitivity of measurement is an important issue in its design. Two operating mechanisms used in prior optical sensors are evanescent wave sensing or surface plasmon excitation. In this dissertation, we present a sensor with a directional coupler structure in which a measurand to be detected is interfaced with one side of the cladding. The analysis shows that it is possible to make a high resolution device by adjusting the design parameters. The dimensions and materials used in an optimized design are presented.

Designing Birefringent Filters For Solid-State Lasers

NASA Technical Reports Server (NTRS)

Monosmith, Bryan

1992-01-01

Mathematical model enables design of filter assembly of birefringent plates as integral part of resonator cavity of tunable solid-state laser. Proper design treats polarization eigenstate of entire resonator as function of wavelength. Program includes software modules for variety of optical elements including Pockels cell, laser rod, quarter- and half-wave plates, Faraday rotator, and polarizers.

A computational imaging target specific detectivity metric

NASA Astrophysics Data System (ADS)

Preece, Bradley L.; Nehmetallah, George

2017-05-01

Due to the large quantity of low-cost, high-speed computational processing available today, computational imaging (CI) systems are expected to have a major role for next generation multifunctional cameras. The purpose of this work is to quantify the performance of theses CI systems in a standardized manner. Due to the diversity of CI system designs that are available today or proposed in the near future, significant challenges in modeling and calculating a standardized detection signal-to-noise ratio (SNR) to measure the performance of these systems. In this paper, we developed a path forward for a standardized detectivity metric for CI systems. The detectivity metric is designed to evaluate the performance of a CI system searching for a specific known target or signal of interest, and is defined as the optimal linear matched filter SNR, similar to the Hotelling SNR, calculated in computational space with special considerations for standardization. Therefore, the detectivity metric is designed to be flexible, in order to handle various types of CI systems and specific targets, while keeping the complexity and assumptions of the systems to a minimum.

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.

Laser designator protection filter for see-spot thermal imaging systems

NASA Astrophysics Data System (ADS)

Donval, Ariela; Fisher, Tali; Lipman, Ofir; Oron, Moshe

2012-06-01

In some cases the FLIR has an open window in the 1.06 micrometer wavelength range; this capability is called 'see spot' and allows seeing a laser designator spot using the FLIR. A problem arises when the returned laser energy is too high for the camera sensitivity, and therefore can cause damage to the sensor. We propose a non-linear, solid-state dynamic filter solution protecting from damage in a passive way. Our filter blocks the transmission, only if the power exceeds a certain threshold as opposed to spectral filters that block a certain wavelength permanently. In this paper we introduce the Wideband Laser Protection Filter (WPF) solution for thermal imaging systems possessing the ability to see the laser spot.

Intermediate-Band Photometric Luminosity Descrimination for M Stars

NASA Astrophysics Data System (ADS)

Robertson, T. H.; Furiak, N. M.

1995-12-01

Synthetic photometry has been used to design an intermediate-band filter to be used with CCD cameras to facilitate the luminosity classification of M stars. Spectrophotometric data published by Gunn & Stryker (1983) were used to test various bandwidths and centers. Based on these calculations an intermediate-band filter has been purchased. This filter is being used in conjunction with standard BVRI filters to test its effectiveness in luminosity classification of M stars having a wide range of temperatures and different chemical compositions. The results of the theoretical calculations, filter design specifications and preliminary results of the testing program are presented. This research is supported in part by funds provided by Ball State University, The Fund for Astrophysical Research and the Indiana Academy of Science.

Optimal design of active EMC filters

NASA Astrophysics Data System (ADS)

Chand, B.; Kut, T.; Dickmann, S.

2013-07-01

A recent trend in automotive industry is adding electrical drive systems to conventional drives. The electrification allows an expansion of energy sources and provides great opportunities for environmental friendly mobility. The electrical powertrain and its components can also cause disturbances which couple into nearby electronic control units and communication cables. Therefore the communication can be degraded or even permanently disrupted. To minimize these interferences, different approaches are possible. One possibility is to use EMC filters. However, the diversity of filters is very large and the determination of an appropriate filter for each application is time-consuming. Therefore, the filter design is determined by using a simulation tool including an effective optimization algorithm. This method leads to improvements in terms of weight, volume and cost.

Adaptive clutter rejection filters for airborne Doppler weather radar applied to the detection of low altitude windshear

NASA Technical Reports Server (NTRS)

Keel, Byron M.

1989-01-01

An optimum adaptive clutter rejection filter for use with airborne Doppler weather radar is presented. The radar system is being designed to operate at low-altitudes for the detection of windshear in an airport terminal area where ground clutter returns may mask the weather return. The coefficients of the adaptive clutter rejection filter are obtained using a complex form of a square root normalized recursive least squares lattice estimation algorithm which models the clutter return data as an autoregressive process. The normalized lattice structure implementation of the adaptive modeling process for determining the filter coefficients assures that the resulting coefficients will yield a stable filter and offers possible fixed point implementation. A 10th order FIR clutter rejection filter indexed by geographical location is designed through autoregressive modeling of simulated clutter data. Filtered data, containing simulated dry microburst and clutter return, are analyzed using pulse-pair estimation techniques. To measure the ability of the clutter rejection filters to remove the clutter, results are compared to pulse-pair estimates of windspeed within a simulated dry microburst without clutter. In the filter evaluation process, post-filtered pulse-pair width estimates and power levels are also used to measure the effectiveness of the filters. The results support the use of an adaptive clutter rejection filter for reducing the clutter induced bias in pulse-pair estimates of windspeed.

Quantum image median filtering in the spatial domain

NASA Astrophysics Data System (ADS)

Li, Panchi; Liu, Xiande; Xiao, Hong

2018-03-01

Spatial filtering is one principal tool used in image processing for a broad spectrum of applications. Median filtering has become a prominent representation of spatial filtering because its performance in noise reduction is excellent. Although filtering of quantum images in the frequency domain has been described in the literature, and there is a one-to-one correspondence between linear spatial filters and filters in the frequency domain, median filtering is a nonlinear process that cannot be achieved in the frequency domain. We therefore investigated the spatial filtering of quantum image, focusing on the design method of the quantum median filter and applications in image de-noising. To this end, first, we presented the quantum circuits for three basic modules (i.e., Cycle Shift, Comparator, and Swap), and then, we design two composite modules (i.e., Sort and Median Calculation). We next constructed a complete quantum circuit that implements the median filtering task and present the results of several simulation experiments on some grayscale images with different noise patterns. Although experimental results show that the proposed scheme has almost the same noise suppression capacity as its classical counterpart, the complexity analysis shows that the proposed scheme can reduce the computational complexity of the classical median filter from the exponential function of image size n to the second-order polynomial function of image size n, so that the classical method can be speeded up.

Broadband notch filter design for millimeter-wave plasma diagnostics.

PubMed

Furtula, V; Michelsen, P K; Leipold, F; Salewski, M; Korsholm, S B; Meo, F; Nielsen, S K; Stejner, M; Moseev, D; Johansen, T

2010-10-01

Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ∼900 MHz, and a typical insertion loss below 2 dB in the passband of ±9 GHz. The design is based on a fundamental rectangular waveguide with eight cylindrical cavities coupled by T-junction apertures formed as thin slits. Parameters that affect the notch performance such as physical lengths and conductor materials are discussed. The excited resonance mode in the cylindrical cavities is the fundamental TE(11). The performance of the constructed filter is measured using a vector network analyzer monitoring a total bandwidth of 30 GHz. We compare the measurements with numerical simulations.

Design and performance of a high-Tc superconductor coplanar waveguide filter

NASA Technical Reports Server (NTRS)

Chew, Wilbert; Riley, A. L.; Rascoe, Daniel L.; Hunt, Brian D.; Foote, Marc C.; Cooley, Thomas W.; Bajuk, Louis J.

1991-01-01

The design of a coplanar waveguide low-pass filter made of YBa2Cu3O(7-delta) (YBCO) on an LaAlO3 substrate is described. Measurements were incorporated into simple models for microwave CAD analysis to develop a final design. The patterned and packaged coplanar waveguide low-pass filter of YBCO, with dimensions suited for integrated circuits, exhibited measured insertion losses when cooled in liquid nitrogen superior to those of a similarly cooled thin-film copper filter throughout the 0 to 9.5 GHz passband. Coplanar waveguide models for use with thin-film normal metal (with thickness either greater or less than the skin depth) and YBCO are discussed and used to compare the losses of the measured YBCO and copper circuits.

Compact triple band-stop filter using novel epsilon-shaped metamaterial with lumped capacitor

NASA Astrophysics Data System (ADS)

Ali, W. A. E.; Hamdalla, M. Z. M.

2018-04-01

This paper presents the design of a novel epsilon-shaped metamaterial unit cell structure that is applicable for single-band and multi-band applications. A closed-form formulas to control the resonance frequencies of the proposed design are included. The proposed unit cell, which exhibits negative permeability at its frequency bands, is etched from the ground plane to form a band-stop filter. The filter design is constructed to validate the band-notched characteristics of the proposed unit cell. A lumped capacitor is inserted for size reduction purpose in addition to multi-resonance generation. The fundamental resonance frequency is translated from 3.62 GHz to 2.45 GHz, which means that the filter size will be more compact (more than 32% size reduction). The overall size of the proposed filter is 13 × 6 × 1.524 mm3, where the electrical size is 0.221λg × 0.102λg × 0.026λg at the lower frequency band (2.45 GHz). Two other resonance frequencies are generated at 5.3 GHz and 9.2 GHz, which confirm the multi-band behavior of the proposed filter. Good agreement between simulated and measured characteristics of the fabricated filter prototype is achieved.

Blocking Filters with Enhanced Throughput for X-Ray Microcalorimetry

NASA Technical Reports Server (NTRS)

Grove, David; Betcher, Jacob; Hagen, Mark

2012-01-01

New and improved blocking filters (see figure) have been developed for microcalorimeters on several mission payloads, made of high-transmission polyimide support mesh, that can replace the nickel mesh used in previous blocking filter flight designs. To realize the resolution and signal sensitivity of today s x-ray microcalorimeters, significant improvements in the blocking filter stack are needed. Using high-transmission polyimide support mesh, it is possible to improve overall throughput on a typical microcalorimeter such as Suzaku s X-ray Spectrometer by 11%, compared to previous flight designs. Using polyimide to replace standard metal mesh means the mesh will be transparent to energies 3 keV and higher. Incorporating polyimide s advantageous strength-to-weight ratio, thermal stability, and transmission characteristics permits thinner filter materials, significantly enhancing through - put. A prototype contamination blocking filter for ASTRO-H has passed QT-level acoustic testing. Resistive traces can also be incorporated to provide decontamination capability to actively restore filter performance in orbit.

Reduced size dual band pass filters for RFID applications with excellent bandpass/bandstop characteristics

NASA Astrophysics Data System (ADS)

Abdalla, M. A.; Choudhary, D. Kumar; Chaudhary, R. Kumar

2018-02-01

This paper presents the design of two reduced size dual-band metamaterial bandpass filters and its simulation followed by measurements of proposed filters. These filters are supporting different frequency bands and primarily could be utilize in radio frequency identification (RFID) application. The filter includes three cells in which two are symmetrical and both inductively coupled with the third cell which is present in between them. In the proposed designs, three different metamaterial composite right/left handed (CRLH) cell resonators have been analysed for compactness. The CRLH cell consists of an interdigital capacitor, a stub/meander line/spiral inductor and a via to connect the top of the structure and ground plane. Finally, the proposed dual band bandpass filters (using meander line and spiral inductor) are showing size reduction by 65% and 50% (with 25% operating frequency reduction), respectively, in comparison with reference filter using stub inductor. More than 30 dB attenuation has been achieved between the two passbands.

Correlation of Electric Field and Critical Design Parameters for Ferroelectric Tunable Microwave Filters

NASA Technical Reports Server (NTRS)

Subramanyam, Guru; VanKeuls, Fred W.; Miranda, Felix A.; Canedy, Chadwick L.; Aggarwal, Sanjeev; Venkatesan, Thirumalai; Ramesh, Ramamoorthy

2000-01-01

The correlation of electric field and critical design parameters such as the insertion loss, frequency ability return loss, and bandwidth of conductor/ferroelectric/dielectric microstrip tunable K-band microwave filters is discussed in this work. This work is based primarily on barium strontium titanate (BSTO) ferroelectric thin film based tunable microstrip filters for room temperature applications. Two new parameters which we believe will simplify the evaluation of ferroelectric thin films for tunable microwave filters, are defined. The first of these, called the sensitivity parameter, is defined as the incremental change in center frequency with incremental change in maximum applied electric field (EPEAK) in the filter. The other, the loss parameter, is defined as the incremental or decremental change in insertion loss of the filter with incremental change in maximum applied electric field. At room temperature, the Au/BSTO/LAO microstrip filters exhibited a sensitivity parameter value between 15 and 5 MHz/cm/kV. The loss parameter varied for different bias configurations used for electrically tuning the filter. The loss parameter varied from 0.05 to 0.01 dB/cm/kV at room temperature.

Technical Note: On maximizing Cherenkov emissions from medical linear accelerators.

PubMed

Shrock, Zachary; Yoon, Suk W; Gunasingha, Rathnayaka; Oldham, Mark; Adamson, Justus

2018-04-19

Cherenkov light during MV radiotherapy has recently found imaging and therapeutic applications but is challenged by relatively low fluence. Our purpose is to investigate the feasibility of increasing Cherenkov light production during MV radiotherapy by increasing photon energy and applying specialized beam-hardening filtration. GAMOS 5.0.0, a GEANT4-based framework for Monte Carlo simulations, was used to model standard clinical linear accelerator primary photon beams. The photon source was incident upon a 17.8 cm 3 cubic water phantom with a 94 cm source to surface distance. Dose and Cherenkov production was determined at depths of 3-9 cm. Filtration was simulated 15 cm below the photon beam source. Filter materials included aluminum, iron, and copper with thicknesses of 2-20 cm. Histories used depended on the level of attenuation from the filter, ranging from 100 million to 2 billion. Comparing average dose per history also allowed for evaluation of dose-rate reduction for different filters. Overall, increasing photon beam energy is more effective at improving Cherenkov production per unit dose than is filtration, with a standard 18 MV beam yielding 3.3-4.0× more photons than 6 MV. Introducing an aluminum filter into an unfiltered 2400 cGy/min 10 MV beam increases the Cherenkov production by 1.6-1.7×, while maintaining a clinical dose rate of 300 cGy/min, compared to increases of ~1.5× for iron and copper. Aluminum was also more effective than the standard flattening filter, with the increase over the unfiltered beam being 1.4-1.5× (maintaining 600 cGy/min dose rate) vs 1.3-1.4× for the standard flattening filter. Applying a 10 cm aluminum filter to a standard 18 MV, photon beam increased the Cherenkov production per unit dose to 3.9-4.3× beyond that of 6 MV (vs 3.3-4.0× for 18 MV with no aluminum filter). Through a combination of increasing photon energy and applying specialized beam-hardening filtration, the amount of Cherenkov photons per unit radiotherapy dose can be increased substantially. © 2018 American Association of Physicists in Medicine.

Dense grid sibling frames with linear phase filters

NASA Astrophysics Data System (ADS)

Abdelnour, Farras

2013-09-01

We introduce new 5-band dyadic sibling frames with dense time-frequency grid. Given a lowpass filter satisfying certain conditions, the remaining filters are obtained using spectral factorization. The analysis and synthesis filterbanks share the same lowpass and bandpass filters but have different and oversampled highpass filters. This leads to wavelets approximating shift-invariance. The filters are FIR, have linear phase, and the resulting wavelets have vanishing moments. The filters are designed using spectral factorization method. The proposed method leads to smooth limit functions with higher approximation order, and computationally stable filterbanks.

Control optimization, stabilization and computer algorithms for aircraft applications

NASA Technical Reports Server (NTRS)

1975-01-01

Research related to reliable aircraft design is summarized. Topics discussed include systems reliability optimization, failure detection algorithms, analysis of nonlinear filters, design of compensators incorporating time delays, digital compensator design, estimation for systems with echoes, low-order compensator design, descent-phase controller for 4-D navigation, infinite dimensional mathematical programming problems and optimal control problems with constraints, robust compensator design, numerical methods for the Lyapunov equations, and perturbation methods in linear filtering and control.

Waveguide bandpass filter with easily adjustable transmission zeros and 3-dB bandwidth

NASA Astrophysics Data System (ADS)

Bage, Amit; Das, Sushrut; Murmu, Lakhindar; Pattapu, Udayabhaskar; Biswal, Sonika

2018-07-01

This paper presents a compact waveguide bandpass filter with adjustable transmission zeros (TZs) and bandwidth. The design provides the flexibility to place the TZs at the desired locations for better interference rejection. To demonstrate, initially a three-pole bandpass filter has been designed by placing three single slot resonator structures inside a WR-90 waveguide. Next, two additional asymmetrical slot structures have been used with each of the above resonators to generate two TZs, one on each side of the passband. Since three resonators were used, this process results in six asymmetric slot structures those results in six TZs. The final filter operates at 9.98 GHz with a 3-dB bandwidth of 1.02 GHz and TZs at 8.23/8.70/9.16/10.9/11.6 and 13.115 GHz. Equivalent circuits and necessary design equations have been provided. To validate the simulation, the proposed filter has been fabricated and measured. The measured data show good agreement with simulated data.

Very long stripe-filters for a multispectral detector

NASA Astrophysics Data System (ADS)

Laubier, D.; Mercier Ythier, Renaud

2017-11-01

In order to simplify instrument design, a new linear area CCD sensor has been developed under CNES responsibility. This detector has four lines 6000 13-μm square pixels long with four stripe filters, one in front of each of them. The detector itself was manufactured and mounted by ATMEL, and the filters were made by SAGEM/REOSC. Assembly was done in two ways, one by ATMEL, the other by SESO. CNES was responsible for the overall design and mechanical/optical interfaces. This paper reports the optical part of this work, including filters placement strategy and line spacing. It will be shown how these two features are closely linked to straylight performance. First, a trade-off study was conducted between several concepts: the results of this study will be presented, as well as the filter design and manufacturing results. They show good transmission and excellent rejection. Final performance of the complete prototypes has been measured, and it will be compared to theoretical models.

Closed circuit TV system monitors welding operations

NASA Technical Reports Server (NTRS)

Gilman, M.

1967-01-01

TV camera system that has a special vidicon tube with a gradient density filter is used in remote monitoring of TIG welding of stainless steel. The welding operations involve complex assembly welding tools and skates in areas of limited accessibility.

Fourier Spectral Filter Array for Optimal Multispectral Imaging.

PubMed

Jia, Jie; Barnard, Kenneth J; Hirakawa, Keigo

2016-04-01

Limitations to existing multispectral imaging modalities include speed, cost, range, spatial resolution, and application-specific system designs that lack versatility of the hyperspectral imaging modalities. In this paper, we propose a novel general-purpose single-shot passive multispectral imaging modality. Central to this design is a new type of spectral filter array (SFA) based not on the notion of spatially multiplexing narrowband filters, but instead aimed at enabling single-shot Fourier transform spectroscopy. We refer to this new SFA pattern as Fourier SFA, and we prove that this design solves the problem of optimally sampling the hyperspectral image data.

An acoustic filter based on layered structure

PubMed Central

Steer, Michael B.

2015-01-01

Acoustic filters (AFs) are key components to control wave propagation in multi-frequency systems. We present a design which selectively achieves acoustic filtering with a stop band and passive amplification at the high- and low-frequencies, respectively. Measurement results from the prototypes closely match the design predictions. The AF suppresses the high frequency aliasing echo by 14.5 dB and amplifies the low frequency transmission by 8.0 dB, increasing an axial resolution from 416 to 86 μm in imaging. The AF design approach is proved to be effective in multi-frequency systems. PMID:25829548

Design and fabrication of far ultraviolet filters based on π-multilayer technology in high-k materials

PubMed Central

Wang, Xiao-Dong; Chen, Bo; Wang, Hai-Feng; He, Fei; Zheng, Xin; He, Ling-Ping; Chen, Bin; Liu, Shi-Jie; Cui, Zhong-Xu; Yang, Xiao-Hu; Li, Yun-Peng

2015-01-01

Application of π-multilayer technology is extended to high extinction coefficient materials, which is introduced into metal-dielectric filter design. Metal materials often have high extinction coefficients in far ultraviolet (FUV) region, so optical thickness of metal materials should be smaller than that of the dielectric material. A broadband FUV filter of 9-layer non-periodic Al/MgF2 multilayer was successfully designed and fabricated and it shows high reflectance in 140–180 nm, suppressed reflectance in 120–137 nm and 181–220 nm. PMID:25687255

Design of a broadband band-pass filter with notch-band using new models of coupled transmission lines.

PubMed

Daryasafar, Navid; Baghbani, Somaye; Moghaddasi, Mohammad Naser; Sadeghzade, Ramezanali

2014-01-01

We intend to design a broadband band-pass filter with notch-band, which uses coupled transmission lines in the structure, using new models of coupled transmission lines. In order to realize and present the new model, first, previous models will be simulated in the ADS program. Then, according to the change of their equations and consequently change of basic parameters of these models, optimization and dependency among these parameters and also their frequency response are attended and results of these changes in order to design a new filter are converged.

Nonlinear multilayers as optical limiters

NASA Astrophysics Data System (ADS)

Turner-Valle, Jennifer Anne

1998-10-01

In this work we present a non-iterative technique for computing the steady-state optical properties of nonlinear multilayers and we examine nonlinear multilayer designs for optical limiters. Optical limiters are filters with intensity-dependent transmission designed to curtail the transmission of incident light above a threshold irradiance value in order to protect optical sensors from damage due to intense light. Thin film multilayers composed of nonlinear materials exhibiting an intensity-dependent refractive index are used as the basis for optical limiter designs in order to enhance the nonlinear filter response by magnifying the electric field in the nonlinear materials through interference effects. The nonlinear multilayer designs considered in this work are based on linear optical interference filter designs which are selected for their spectral properties and electric field distributions. Quarter wave stacks and cavity filters are examined for their suitability as sensor protectors and their manufacturability. The underlying non-iterative technique used to calculate the optical response of these filters derives from recognizing that the multi-valued calculation of output irradiance as a function of incident irradiance may be turned into a single-valued calculation of incident irradiance as a function of output irradiance. Finally, the benefits and drawbacks of using nonlinear multilayer for optical limiting are examined and future research directions are proposed.

Design and implement of pack filter module base on embedded firewall

NASA Astrophysics Data System (ADS)

Tian, Libo; Wang, Chen; Yang, Shunbo

2011-10-01

In the traditional security solution conditions, software firewall cannot intercept and respond the invasion before being attacked. And because of the high cost, the hardware firewall does not apply to the security strategy of the end nodes, so we have designed a kind of solution of embedded firewall with hardware and software. With ARM embedding Linux operating system, we have designed packet filter module and intrusion detection module to implement the basic function of firewall. Experiments and results show that that firewall has the advantages of low cost, high processing speed, high safety and the application of the computer terminals. This paper focuses on packet filtering module design and implementation.

High-performance analysis of filtered semantic graphs

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

Buluc, Aydin; Fox, Armando; Gilbert, John R.

2012-01-01

High performance is a crucial consideration when executing a complex analytic query on a massive semantic graph. In a semantic graph, vertices and edges carry "attributes" of various types. Analytic queries on semantic graphs typically depend on the values of these attributes; thus, the computation must either view the graph through a filter that passes only those individual vertices and edges of interest, or else must first materialize a subgraph or subgraphs consisting of only the vertices and edges of interest. The filtered approach is superior due to its generality, ease of use, and memory efficiency, but may carry amore » performance cost. In the Knowledge Discovery Toolbox (KDT), a Python library for parallel graph computations, the user writes filters in a high-level language, but those filters result in relatively low performance due to the bottleneck of having to call into the Python interpreter for each edge. In this work, we use the Selective Embedded JIT Specialization (SEJITS) approach to automatically translate filters defined by programmers into a lower-level efficiency language, bypassing the upcall into Python. We evaluate our approach by comparing it with the high-performance C++ /MPI Combinatorial BLAS engine, and show that the productivity gained by using a high-level filtering language comes without sacrificing performance.« less

Metal removal efficiency, operational life and secondary environmental impacts of a stormwater filter developed from iron-oxide-amended bottom ash.

PubMed

Ilyas, Aamir; Muthanna, Tone M

2017-12-06

The aim of this paper was to conduct pilot-scale column tests on an alternative treatment filter designed for the treatment of highway stormwater in cold climates. The study evaluated adsorption performance of the filter with regard to the four most commonly found metals (Cu, Ni, Pb, and Zn) in highway stormwater. An alternative method was used to estimate the operational life of the filter from the adsorption test data without a breakthrough under high hydraulic loads. The potential environmental impact of the filter was assessed by comparing desorption test data with four different environmental quality standards. The proposed filter achieved high adsorption (over 90%) of the target metals. The comparisons of desorption and leaching data with the environmental standards indicated that iron-oxide/bottom ash was non-hazardous, reusable and without serious environmental risks. The operational life and filter dimensions were highly dependent on rainfall depth, which indicated that the filter design would have to be adapted to suit the climate. To fully appreciate the performance and environmental aspects, the filter unit should be tested in the field and the testing should explicitly include ecotoxicological and life cycle impacts.

[Design Method Analysis and Performance Comparison of Wall Filter for Ultrasound Color Flow Imaging].

PubMed

Wang, Lutao; Xiao, Jun; Chai, Hua

2015-08-01

The successful suppression of clutter arising from stationary or slowly moving tissue is one of the key issues in medical ultrasound color blood imaging. Remaining clutter may cause bias in the mean blood frequency estimation and results in a potentially misleading description of blood-flow. In this paper, based on the principle of general wall-filter, the design process of three classes of filters, infinitely impulse response with projection initialization (Prj-IIR), polynomials regression (Pol-Reg), and eigen-based filters are previewed and analyzed. The performance of the filters was assessed by calculating the bias and variance of a mean blood velocity using a standard autocorrelation estimator. Simulation results show that the performance of Pol-Reg filter is similar to Prj-IIR filters. Both of them can offer accurate estimation of mean blood flow speed under steady clutter conditions, and the clutter rejection ability can be enhanced by increasing the ensemble size of Doppler vector. Eigen-based filters can effectively remove the non-stationary clutter component, and further improve the estimation accuracy for low speed blood flow signals. There is also no significant increase in computation complexity for eigen-based filters when the ensemble size is less than 10.

An Unscented Kalman-Particle Hybrid Filter for Space Object Tracking

NASA Astrophysics Data System (ADS)

Raihan A. V, Dilshad; Chakravorty, Suman

2018-03-01

Optimal and consistent estimation of the state of space objects is pivotal to surveillance and tracking applications. However, probabilistic estimation of space objects is made difficult by the non-Gaussianity and nonlinearity associated with orbital mechanics. In this paper, we present an unscented Kalman-particle hybrid filtering framework for recursive Bayesian estimation of space objects. The hybrid filtering scheme is designed to provide accurate and consistent estimates when measurements are sparse without incurring a large computational cost. It employs an unscented Kalman filter (UKF) for estimation when measurements are available. When the target is outside the field of view (FOV) of the sensor, it updates the state probability density function (PDF) via a sequential Monte Carlo method. The hybrid filter addresses the problem of particle depletion through a suitably designed filter transition scheme. To assess the performance of the hybrid filtering approach, we consider two test cases of space objects that are assumed to undergo full three dimensional orbital motion under the effects of J 2 and atmospheric drag perturbations. It is demonstrated that the hybrid filters can furnish fast, accurate and consistent estimates outperforming standard UKF and particle filter (PF) implementations.

Media filter drain : modified design evaluation.

DOT National Transportation Integrated Search

2014-09-01

The media filter drain (MFD), a stormwater water quality treatment best management practice, consists of media made up of : aggregate, perlite, gypsum and dolomite in a trench located along roadway shoulders with gravel and vegetative pre-filtering f...

Polarization-dependent optics using gauge-field metamaterials

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

Liu, Fu; Xiao, Shiyi; Li, Jensen, E-mail: j.li@bham.ac.uk

2015-12-14

We show that effective gauge field for photons with polarization-split dispersion surfaces, being realized using uniaxial metamaterials, can be used for polarization control with unique opportunities. The metamaterials with the proposed gauge field correspond to a special choice of eigenpolarizations on the Poincaré sphere as pseudo-spins, in contrary to those from either conventional birefringent crystals or optical active media. It gives rise to all-angle polarization control and a generic route to manipulate photon trajectories or polarizations in the pseudo-spin domain. As demonstrations, we show beam splitting (birefringent polarizer), all-angle polarization control, unidirectional polarization filter, and interferometer as various polarization controlmore » devices in the pseudo-spin domain. We expect that more polarization-dependent devices can be designed under the same framework.« less

Analisis fotometrico del cumulo abierto NGC 6611

NASA Astrophysics Data System (ADS)

Suarez Nunez, Johanna

2007-08-01

Matlab programs were designed to apply differential aperture photometry. Two images were taken with a charge-couple device ( CCD ) in the visible V and blue filters, to calculate physical parameters (the flux( f ), the apparent magnitude ( m V ) and its reddening corrected value ( V 0 ), color index ( B- V ) and ( B-V ) 0 , the log of effective temperature (log T eff ), the absolute magnitude ( M V ), the bolometric magnitude ( M B ) & log(L [low *] /[Special characters omitted.] )) of each studied star pertaining to the open cluster NGC 6611. Upon obtaining the parameters, the color-magnitude diagram was graphed and by fitting to the main sequence, the distance modulus and thus the distance to the cluster was found. The stars were assumed to be at the same distance and born at approximately the same moment.

MARS PATHFINDER CAMERA TEST IN SAEF-2

NASA Technical Reports Server (NTRS)

1996-01-01

In the Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2), workers from the Jet Propulsion Laboratory (JPL) are conducting a systems test of the imager for the Mars Pathfinder. Mounted on the Pathfinder lander, the imager (the white cylindrical element the worker is touching) is a specially designed camera featuring a stereo-imaging system with color capability provided by a set of selectable filters. It is mounted on an extendable mast that will pop up after the lander touches down on the Martian surface. The imager will transmit images of the terrain, allowing engineers back on Earth to survey the landing site before the Pathfinder rover is deployed to explore the area. The Mars Pathfinder is scheduled for launch aboard a Delta II expendable launch vehicle on Dec. 2. JPL manages the Pathfinder project for NASA.

[Low level alpha activity measurements with pulse shape discrimination--application to the determination of alpha-nuclides in environmental samples].

PubMed

Satoh, K; Noguchi, M; Higuchi, H; Kitamura, K

1984-12-01

Liquid scintillation counting of alpha rays with pulse shape discrimination was applied to the analysis of 226Ra and 239+240Pu in environmental samples and of alpha-emitters in/on a filter paper. The instrument used in this study was either a specially designed detector or a commercial liquid scintillation counter with an automatic sample changer, both of which were connected to the pulse shape discrimination circuit. The background counting rate in alpha energy region of 5-7 MeV was 0.01 or 0.04 cpm/MeV, respectively. The figure of merit indicating the resolving power for alpha- and beta-particles in time spectrum was found to be 5.7 for the commercial liquid scintillation counter.

Robust information encryption diffractive-imaging-based scheme with special phase retrieval algorithm for a customized data container

NASA Astrophysics Data System (ADS)

Qin, Yi; Wang, Zhipeng; Wang, Hongjuan; Gong, Qiong; Zhou, Nanrun

2018-06-01

The diffractive-imaging-based encryption (DIBE) scheme has aroused wide interesting due to its compact architecture and low requirement of conditions. Nevertheless, the primary information can hardly be recovered exactly in the real applications when considering the speckle noise and potential occlusion imposed on the ciphertext. To deal with this issue, the customized data container (CDC) into DIBE is introduced and a new phase retrieval algorithm (PRA) for plaintext retrieval is proposed. The PRA, designed according to the peculiarity of the CDC, combines two key techniques from previous approaches, i.e., input-support-constraint and median-filtering. The proposed scheme can guarantee totally the reconstruction of the primary information despite heavy noise or occlusion and its effectiveness and feasibility have been demonstrated with simulation results.

Robust control of flexible space vehicles with minimum structural excitation: On-off pulse control of flexible space vehicles

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang

1992-01-01

Both feedback and feedforward control approaches for uncertain dynamical systems (in particular, with uncertainty in structural mode frequency) are investigated. The control objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant uncertainty. Preshaping of an ideal, time optimal control input using a tapped-delay filter is shown to provide a fast settling time with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. It is shown that a properly designed, feedback controller performs well, as compared with a time optimal open loop controller with special preshaping for performance robustness. Also included are two separate papers by the same authors on this subject.

Design of multi-wavelength tunable filter based on Lithium Niobate

NASA Astrophysics Data System (ADS)

Zhang, Ailing; Yao, Yuan; Zhang, Yue; Song, Hongyun

2018-05-01

A multi-wavelength tunable filter is designed. It consists of multiple waveguides among multiple waveguide gratings. A pair of electrodes were placed on both sides of each waveguide. The tunable filter uses the electro-optic effect of Lithium Niobate to tune the phase caused by each waveguide. Consequently, the wavelength and wavelength spacing of the filter are tuned by changing external voltages added on the electrode pairs. The tunable property of the filter is analyzed by phase matching condition and transfer-matrix method. Numerical results show that not only multiple wavelengths with narrow bandwidth are tuned with nearly equal spacing by synchronously changing the voltages added on all electrode pairs, but also the number of wavelengths is determined by the number of phase shifts caused by electrode pairs. Furthermore, due to the electro-optic effect of Lithium Niobate, the tuning speed of the filter can reach the order of ns.

Design and analysis of planar spiral resonator bandstop filter for microwave frequency

NASA Astrophysics Data System (ADS)

Motakabber, S. M. A.; Shaifudin Suharsono, Muhammad

2017-11-01

In microwave frequency, a spiral resonator can act as either frequency reject or acceptor circuits. A planar logarithmic spiral resonator bandstop filter has been developed based on this property. This project focuses on the rejection property of the spiral resonator. The performance analysis of the exhibited filter circuit has been performed by using scattering parameters (S-parameters) technique in the ultra-wideband microwave frequency. The proposed filter is built, simulated and S-parameters analysis have been accomplished by using electromagnetic simulation software CST microwave studio. The commercial microwave substrate Taconic TLX-8 has been used to build this filter. Experimental results showed that the -10 dB rejection bandwidth of the filter is 2.32 GHz and central frequency is 5.72 GHz which is suitable for ultra-wideband applications. The proposed design has been full of good compliance with the simulated and experimental results here.

The use of microbial-earthworm ecofilters for wastewater treatment with special attention to influencing factors in performance: A review.

PubMed

Jiang, Luhua; Liu, Yunguo; Hu, Xinjiang; Zeng, Guangming; Wang, Hui; Zhou, Lu; Tan, Xiaofei; Huang, Binyan; Liu, Shaobo; Liu, Simian

2016-01-01

With the unique advantages of lower operational and maintenance cost, the use of microbial-earthworm ecofilters (MEEs) for the wastewater treatment has been increasing rapidly in the recent years. This paper provided an overview of the research activities on the use of MEEs for removing pollutants from various wastewater throughout the world. However, the long-term effective treatment performance and sustainable operation of this system still remain a challenge since the treatment performance would be affected by design parameters, operational conditions, and environmental factors. In order to promote the treatment performance, therefore, this paper also provided and summarized the influencing factors of pollutants removal in MEEs. The design parameters and operational conditions of MEEs include earthworm species and load, filter media type, hydraulic loading rate, nutrient load, packing bed height, chemical factors and temperature. Lastly, this review highlighted the further research on these issues to improve performance and sustainability of MEEs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurement of Motion Transfer Functions for Mirror Suspensions

NASA Astrophysics Data System (ADS)

Stuver, Amber; Beilby, Mark; Glancy, Aran; Gonzalez, Gabriela

2001-04-01

Interferometric gravitational wave detectors, such as LIGO, use mirrors suspended in pendulums. The current LIGO dectors use simple pendulums, but advanced LIGO detectors will use multiple pendulums with some stages on soft vertical springs. A drawback of the a multiple pendulum design is that it is difficult to model and predict cross couplings from one vibrational mode to another due to slight unavoidable asymmetries in the real system. Of most concern are the couplings to motion along the optical axis and into angular motions, which have the most potential to contaminate data. Our research focuses on the experimental testing of the pendulum designs for cross couplings with a special dedicated shaking stage. The cross couplings in each degree of freedom, their isolation and damping are investigated in this research though the measurement of transfer functions as filtered though the suspension system. This research is supported by The Pennsylvania State University, the NSF Grant no. PHY-9870032, and the REU program at The Pennsylvania State University.

Microprocessor realizations of range rate filters

NASA Technical Reports Server (NTRS)

1979-01-01

The performance of five digital range rate filters is evaluated. A range rate filter receives an input of range data from a radar unit and produces an output of smoothed range data and its estimated derivative range rate. The filters are compared through simulation on an IBM 370. Two of the filter designs are implemented on a 6800 microprocessor-based system. Comparisons are made on the bases of noise variance reduction ratios and convergence times of the filters in response to simulated range signals.

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

Arndt, T.E., Fluor Daniel Hanford

A previous evaluation documented in report WHC-SD-GN-RPT-30005, Rev. 0, titled ``Evaluation on Self-Contained High Efficiency Particulate Filters,`` revealed that the SCHEPA filters do not have required documentation to be in compliance with the design, testing, and fabrication standards required in ASME N-509, ASME N-510, and MIL-F-51068. These standards are required by DOE Order 6430.IA. Without this documentation, filter adequacy cannot be verified. The existing SCHEPA filters can be removed and replaced with new filters and filter housing which meet current codes and standards.

Application of DFT Filter Banks and Cosine Modulated Filter Banks in Filtering

NASA Technical Reports Server (NTRS)

Lin, Yuan-Pei; Vaidyanathan, P. P.

1994-01-01

None given. This is a proposal for a paper to be presented at APCCAS '94 in Taipei, Taiwan. (From outline): This work is organized as follows: Sec. II is devoted to the construction of the new 2m channel under-decimated DFT filter bank. Implementation and complexity of this DFT filter bank are discussed therein. IN a similar manner, the new 2m channel cosine modulated filter bank is discussed in Sec. III. Design examples are given in Sec. IV.

An Intrinsically Switchable Ladder-Type Ferroelectric BST-on-Si Composite FBAR Filter.

PubMed

Lee, Seungku; Mortazawi, Amir

2016-03-01

This paper presents a ladder-type bulk acoustic wave (BAW) intrinsically switchable filter based on ferroelectric thin-film bulk acoustic resonators (FBARs). The switchable filter can be turned on and off by the application of an external bias voltage due to the electrostrictive effect in thin-film ferroelectrics. In this paper, Barium Strontium Titanate (BST) is used as the ferroelectric material. A systematic design approach for switchable ladder-type ferroelectric filters is provided based on required filter specifications. A switchable filter is implemented in the form of a BST-on-Si composite structure to control the effective electromechanical coupling coefficient of FBARs. As an experimental verification, a 2.5-stage intrinsically switchable BST-on-Si composite FBAR filter is designed, fabricated, and measured. Measurement results for a typical BST-on-Si composite FBAR show a resonator mechanical quality factor (Q(m)) of 971, as well as a (Q(m)) × f of 2423 GHz. The filter presented here provides a measured insertion loss of 7.8 dB, out-of-band rejection of 26 dB, and fractional bandwidth of 0.33% at 2.5827 GHz when the filter is in the on state at a dc bias of 40 V. In its off state, the filter exhibits an isolation of 31 dB.

Optical fiber sensors measurement system and special fibers improvement

NASA Astrophysics Data System (ADS)

Jelinek, Michal; Hrabina, Jan; Hola, Miroslava; Hucl, Vaclav; Cizek, Martin; Rerucha, Simon; Lazar, Josef; Mikel, Bretislav

2017-06-01

We present method for the improvement of the measurement accuracy in the optical frequency spectra measurements based on tunable optical filters. The optical filter was used during the design and realization of the measurement system for the inspection of the fiber Bragg gratings. The system incorporates a reference block for the compensation of environmental influences, an interferometric verification subsystem and a PC - based control software implemented in LabView. The preliminary experimental verification of the measurement principle and the measurement system functionality were carried out on a testing rig with a specially prepared concrete console in the UJV Řež. The presented system is the laboratory version of the special nuclear power plant containment shape deformation measurement system which was installed in the power plant Temelin during last year. On the base of this research we started with preparation other optical fiber sensors to nuclear power plants measurement. These sensors will be based on the microstructured and polarization maintaining optical fibers. We started with development of new methods and techniques of the splicing and shaping optical fibers. We are able to made optical tapers from ultra-short called adiabatic with length around 400 um up to long tapers with length up to 6 millimeters. We developed new techniques of splicing standard Single Mode (SM) and Multimode (MM) optical fibers and splicing of optical fibers with different diameters in the wavelength range from 532 to 1550 nm. Together with development these techniques we prepared other techniques to splicing and shaping special optical fibers like as Polarization-Maintaining (PM) or hollow core Photonic Crystal Fiber (PCF) and theirs cross splicing methods with focus to minimalize backreflection and attenuation. The splicing special optical fibers especially PCF fibers with standard telecommunication and other SM fibers can be done by our developed techniques. Adjustment of the splicing process has to be prepared for any new optical fibers and new fibers combinations. The splicing of the same types of fibers from different manufacturers can be adjusted by several tested changes in the splicing process. We are able to splice PCF with standard telecommunication fiber with attenuation up to 2 dB. The method is also presented. Development of these new techniques and methods of the optical fibers splicing are made with respect to using these fibers to another research and development in the field of optical fibers sensors, laser frequency stabilization and laser interferometry based on optical fibers. Especially for the field of laser frequency stabilization we developed and present new techniques to closing microstructured fibers with gases inside.

High-power converters for space applications

NASA Technical Reports Server (NTRS)

Park, J. N.; Cooper, Randy

1991-01-01

Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

An Enhanced Non-Coherent Pre-Filter Design for Tracking Error Estimation in GNSS Receivers.

PubMed

Luo, Zhibin; Ding, Jicheng; Zhao, Lin; Wu, Mouyan

2017-11-18

Tracking error estimation is of great importance in global navigation satellite system (GNSS) receivers. Any inaccurate estimation for tracking error will decrease the signal tracking ability of signal tracking loops and the accuracies of position fixing, velocity determination, and timing. Tracking error estimation can be done by traditional discriminator, or Kalman filter-based pre-filter. The pre-filter can be divided into two categories: coherent and non-coherent. This paper focuses on the performance improvements of non-coherent pre-filter. Firstly, the signal characteristics of coherent and non-coherent integration-which are the basis of tracking error estimation-are analyzed in detail. After that, the probability distribution of estimation noise of four-quadrant arctangent (ATAN2) discriminator is derived according to the mathematical model of coherent integration. Secondly, the statistical property of observation noise of non-coherent pre-filter is studied through Monte Carlo simulation to set the observation noise variance matrix correctly. Thirdly, a simple fault detection and exclusion (FDE) structure is introduced to the non-coherent pre-filter design, and thus its effective working range for carrier phase error estimation extends from (-0.25 cycle, 0.25 cycle) to (-0.5 cycle, 0.5 cycle). Finally, the estimation accuracies of discriminator, coherent pre-filter, and the enhanced non-coherent pre-filter are evaluated comprehensively through the carefully designed experiment scenario. The pre-filter outperforms traditional discriminator in estimation accuracy. In a highly dynamic scenario, the enhanced non-coherent pre-filter provides accuracy improvements of 41.6%, 46.4%, and 50.36% for carrier phase error, carrier frequency error, and code phase error estimation, respectively, when compared with coherent pre-filter. The enhanced non-coherent pre-filter outperforms the coherent pre-filter in code phase error estimation when carrier-to-noise density ratio is less than 28.8 dB-Hz, in carrier frequency error estimation when carrier-to-noise density ratio is less than 20 dB-Hz, and in carrier phase error estimation when carrier-to-noise density belongs to (15, 23) dB-Hz ∪ (26, 50) dB-Hz.

An Enhanced Non-Coherent Pre-Filter Design for Tracking Error Estimation in GNSS Receivers

PubMed Central

Luo, Zhibin; Ding, Jicheng; Zhao, Lin; Wu, Mouyan

2017-01-01

Tracking error estimation is of great importance in global navigation satellite system (GNSS) receivers. Any inaccurate estimation for tracking error will decrease the signal tracking ability of signal tracking loops and the accuracies of position fixing, velocity determination, and timing. Tracking error estimation can be done by traditional discriminator, or Kalman filter-based pre-filter. The pre-filter can be divided into two categories: coherent and non-coherent. This paper focuses on the performance improvements of non-coherent pre-filter. Firstly, the signal characteristics of coherent and non-coherent integration—which are the basis of tracking error estimation—are analyzed in detail. After that, the probability distribution of estimation noise of four-quadrant arctangent (ATAN2) discriminator is derived according to the mathematical model of coherent integration. Secondly, the statistical property of observation noise of non-coherent pre-filter is studied through Monte Carlo simulation to set the observation noise variance matrix correctly. Thirdly, a simple fault detection and exclusion (FDE) structure is introduced to the non-coherent pre-filter design, and thus its effective working range for carrier phase error estimation extends from (−0.25 cycle, 0.25 cycle) to (−0.5 cycle, 0.5 cycle). Finally, the estimation accuracies of discriminator, coherent pre-filter, and the enhanced non-coherent pre-filter are evaluated comprehensively through the carefully designed experiment scenario. The pre-filter outperforms traditional discriminator in estimation accuracy. In a highly dynamic scenario, the enhanced non-coherent pre-filter provides accuracy improvements of 41.6%, 46.4%, and 50.36% for carrier phase error, carrier frequency error, and code phase error estimation, respectively, when compared with coherent pre-filter. The enhanced non-coherent pre-filter outperforms the coherent pre-filter in code phase error estimation when carrier-to-noise density ratio is less than 28.8 dB-Hz, in carrier frequency error estimation when carrier-to-noise density ratio is less than 20 dB-Hz, and in carrier phase error estimation when carrier-to-noise density belongs to (15, 23) dB-Hz ∪ (26, 50) dB-Hz. PMID:29156581

Flat-Passband 3 × 3 Interleaving Filter Designed With Optical Directional Couplers in Lattice Structure

NASA Astrophysics Data System (ADS)

Wang, Qi Jie; Zhang, Ying; Soh, Yeng Chai

2005-12-01

This paper presents a novel lattice optical delay-line circuit using 3 × 3 directional couplers to implement three-port optical interleaving filters. It is shown that the proposed circuit can deliver three channels of 2pi/3 phase-shifted interleaving transmission spectra if the coupling ratios of the last two directional couplers are selected appropriately. The other performance requirements of an optical interleaver can be achieved by designing the remaining part of the lattice circuit. A recursive synthesis design algorithm is developed to calculate the design parameters of the lattice circuit that will yield the desired filter response. As illustrative examples, interleavers with maximally flat-top passband transmission and with given transmission performance on passband ripples and passband bandwidth, respectively, are designed to verify the effectiveness of the proposed design scheme.

pH Meter probe assembly

DOEpatents

Hale, C.J.

1983-11-15

An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe. 1 fig.

pH Meter probe assembly

DOEpatents

Hale, Charles J.

1983-01-01

An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe.

Linear variable narrow bandpass optical filters in the far infrared (Conference Presentation)

NASA Astrophysics Data System (ADS)

Rahmlow, Thomas D.

2017-06-01

We are currently developing linear variable filters (LVF) with very high wavelength gradients. In the visible, these filters have a wavelength gradient of 50 to 100 nm/mm. In the infrared, the wavelength gradient covers the range of 500 to 900 microns/mm. Filter designs include band pass, long pass and ulta-high performance anti-reflection coatings. The active area of the filters is on the order of 5 to 30 mm along the wavelength gradient and up to 30 mm in the orthogonal, constant wavelength direction. Variation in performance along the constant direction is less than 1%. Repeatable performance from filter to filter, absolute placement of the filter relative to a substrate fiducial and, high in-band transmission across the full spectral band is demonstrated. Applications include order sorting filters, direct replacement of the spectrometer and hyper-spectral imaging. Off-band rejection with an optical density of greater than 3 allows use of the filter as an order sorting filter. The linear variable order sorting filters replaces other filter types such as block filters. The disadvantage of block filters is the loss of pixels due to the transition between filter blocks. The LVF is a continuous gradient without a discrete transition between filter wavelength regions. If the LVF is designed as a narrow band pass filter, it can be used in place of a spectrometer thus reducing overall sensor weight and cost while improving the robustness of the sensor. By controlling the orthogonal performance (smile) the LVF can be sized to the dimensions of the detector. When imaging on to a 2 dimensional array and operating the sensor in a push broom configuration, the LVF spectrometer performs as a hyper-spectral imager. This paper presents performance of LVF fabricated in the far infrared on substrates sized to available detectors. The impact of spot size, F-number and filter characterization are presented. Results are also compared to extended visible LVF filters.

Effect of filter designs on hydraulic properties and well efficiency.

PubMed

Kim, Byung-Woo

2014-09-01

To analyze the effect of filter pack arrangement on the hydraulic properties and the well efficiency of a well design, a step drawdown was conducted in a sand-filled tank model. Prior to the test, a single filter pack (SFP), granule only, and two dual filter packs (DFPs), type A (granule-pebble) and type B (pebble-granule), were designed to surround the well screen. The hydraulic properties and well efficiencies related to the filter packs were evaluated using the Hazen's, Eden-Hazel's, Jacob's, and Labadie-Helweg's methods. The results showed that the hydraulic properties and well efficiency of the DFPs were higher than those of a SFP, and the clogging effect and wellhead loss related to the aquifer material were the lowest owing to the grain size and the arrangement of the filter pack. The hydraulic conductivity of the DFPs types A and B was about 1.41 and 6.43 times that of a SFP, respectively. In addition, the well efficiency of the DFPs types A and B was about 1.38 and 1.60 times that of the SFP, respectively. In this study, hydraulic property and well efficiency changes were observed according to the variety of the filter pack used. The results differed from the predictions of previous studies on the grain-size ratio. Proper pack-aquifer ratios and filter pack arrangements are primary factors in the construction of efficient water wells, as is the grain ratio, intrinsic permeability (k), and hydraulic conductivity (K) between the grains of the filter packs and the grains of the aquifer. © 2014, National Ground Water Association.

Optimized FPGA Implementation of Multi-Rate FIR Filters Through Thread Decomposition

NASA Technical Reports Server (NTRS)

Zheng, Jason Xin; Nguyen, Kayla; He, Yutao

2010-01-01

Multirate (decimation/interpolation) filters are among the essential signal processing components in spaceborne instruments where Finite Impulse Response (FIR) filters are often used to minimize nonlinear group delay and finite-precision effects. Cascaded (multi-stage) designs of Multi-Rate FIR (MRFIR) filters are further used for large rate change ratio, in order to lower the required throughput while simultaneously achieving comparable or better performance than single-stage designs. Traditional representation and implementation of MRFIR employ polyphase decomposition of the original filter structure, whose main purpose is to compute only the needed output at the lowest possible sampling rate. In this paper, an alternative representation and implementation technique, called TD-MRFIR (Thread Decomposition MRFIR), is presented. The basic idea is to decompose MRFIR into output computational threads, in contrast to a structural decomposition of the original filter as done in the polyphase decomposition. Each thread represents an instance of the finite convolution required to produce a single output of the MRFIR. The filter is thus viewed as a finite collection of concurrent threads. The technical details of TD-MRFIR will be explained, first showing its applicability to the implementation of downsampling, upsampling, and resampling FIR filters, and then describing a general strategy to optimally allocate the number of filter taps. A particular FPGA design of multi-stage TD-MRFIR for the L-band radar of NASA's SMAP (Soil Moisture Active Passive) instrument is demonstrated; and its implementation results in several targeted FPGA devices are summarized in terms of the functional (bit width, fixed-point error) and performance (time closure, resource usage, and power estimation) parameters.

40 CFR 53.35 - Test procedure for Class II and Class III methods for PM2.5 and PM-2.5

Code of Federal Regulations, 2010 CFR

2010-07-01

... reference method samplers shall be of single-filter design (not multi-filter, sequential sample design... and multiplicative bias (comparative slope and intercept). (1) For each test site, calculate the mean...

40 CFR 53.35 - Test procedure for Class II and Class III methods for PM2.5 and PM-2.5

Code of Federal Regulations, 2011 CFR

2011-07-01

... reference method samplers shall be of single-filter design (not multi-filter, sequential sample design... and multiplicative bias (comparative slope and intercept). (1) For each test site, calculate the mean...

40 CFR 53.35 - Test procedure for Class II and Class III methods for PM2.5 and PM−2.5.

Code of Federal Regulations, 2012 CFR

2012-07-01

... reference method samplers shall be of single-filter design (not multi-filter, sequential sample design... and multiplicative bias (comparative slope and intercept). (1) For each test site, calculate the mean...

42 CFR 84.177 - Inhalation and exhalation valves; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... air from adversely affecting filters, except where filters are specifically designed to resist... DEVICES Non-Powered Air-Purifying Particulate Respirators § 84.177 Inhalation and exhalation valves... external influence; and (3) Designed and constructed to prevent inward leakage of contaminated air. ...

42 CFR 84.177 - Inhalation and exhalation valves; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... air from adversely affecting filters, except where filters are specifically designed to resist... DEVICES Non-Powered Air-Purifying Particulate Respirators § 84.177 Inhalation and exhalation valves... external influence; and (3) Designed and constructed to prevent inward leakage of contaminated air. ...

AgBufferBuilder: A geographic information system (GIS) tool for precision design and performance assessment of filter strips

Treesearch

M. G. Dosskey; S. Neelakantan; T. G. Mueller; T. Kellerman; M. J. Helmers; E. Rienzi

2015-01-01

Spatially nonuniform runoif reduces the water qua1iry perfortnance of constant- width filter strips. A geographic inlormation system (Gls)-based tool was developed and tested that ernploys terrain analysis to account lor spatially nonuniform runoffand produce more ellbctive filter strip designs.The computer program,AgBufTerBuilder, runs with ATcGIS versions 10.0 and 10...

Joint Transmit and Receive Filter Optimization for Sub-Nyquist Delay-Doppler Estimation

NASA Astrophysics Data System (ADS)

Lenz, Andreas; Stein, Manuel S.; Swindlehurst, A. Lee

2018-05-01

In this article, a framework is presented for the joint optimization of the analog transmit and receive filter with respect to a parameter estimation problem. At the receiver, conventional signal processing systems restrict the two-sided bandwidth of the analog pre-filter $B$ to the rate of the analog-to-digital converter $f_s$ to comply with the well-known Nyquist-Shannon sampling theorem. In contrast, here we consider a transceiver that by design violates the common paradigm $B\\leq f_s$. To this end, at the receiver, we allow for a higher pre-filter bandwidth $B>f_s$ and study the achievable parameter estimation accuracy under a fixed sampling rate when the transmit and receive filter are jointly optimized with respect to the Bayesian Cram\\'{e}r-Rao lower bound. For the case of delay-Doppler estimation, we propose to approximate the required Fisher information matrix and solve the transceiver design problem by an alternating optimization algorithm. The presented approach allows us to explore the Pareto-optimal region spanned by transmit and receive filters which are favorable under a weighted mean squared error criterion. We also discuss the computational complexity of the obtained transceiver design by visualizing the resulting ambiguity function. Finally, we verify the performance of the optimized designs by Monte-Carlo simulations of a likelihood-based estimator.

Development of a New Arterial-Line Filter Design Using Computational Fluid Dynamics Analysis

PubMed Central

Herbst, Daniel P.; Najm, Hani K.

2012-01-01

Abstract: Arterial-line filters used during extracorporeal circulation continue to rely on the physical properties of a wetted micropore and reductions in blood flow velocity to affect air separation from the circulating blood volume. Although problems associated with air embolism during cardiac surgery persist, a number of investigators have concluded that further improvements in filtration are needed to enhance air removal during cardiopulmonary bypass procedures. This article reviews theoretical principles of micropore filter technology and outlines the development of a new arterial-line filter concept using computational fluid dynamics analysis. Manufacturer-supplied data of a micropore screen and experimental results taken from an ex vivo test circuit were used to define the inputs needed for numerical modeling of a new filter design. Flow patterns, pressure distributions, and velocity profiles predicted with computational fluid dynamics softwarewere used to inform decisions on model refinements and how to achieve initial design goals of ≤225 mL prime volume and ≤500 cm2 of screen surface area. Predictions for optimal model geometry included a screen angle of 56° from the horizontal plane with a total surface area of 293.9 cm2 and a priming volume of 192.4 mL. This article describes in brief the developmental process used to advance a new filter design and supports the value of numerical modeling in this undertaking. PMID:23198394

Development of a new arterial-line filter design using computational fluid dynamics analysis.

PubMed

Herbst, Daniel P; Najm, Hani K

2012-09-01

Arterial-line filters used during extracorporeal circulation continue to rely on the physical properties of a wetted micropore and reductions in blood flow velocity to affect air separation from the circulating blood volume. Although problems associated with air embolism during cardiac surgery persist, a number of investigators have concluded that further improvements in filtration are needed to enhance air removal during cardiopulmonary bypass procedures. This article reviews theoretical principles of micropore filter technology and outlines the development of a new arterial-line filter concept using computational fluid dynamics analysis. Manufacturer-supplied data of a micropore screen and experimental results taken from an ex vivo test circuit were used to define the inputs needed for numerical modeling of a new filter design. Flow patterns, pressure distributions, and velocity profiles predicted with computational fluid dynamics software were used to inform decisions on model refinements and how to achieve initial design goals of < or = 225 mL prime volume and < or = 500 cm2 of screen surface area. Predictions for optimal model geometry included a screen angle of 56 degrees from the horizontal plane with a total surface area of 293.9 cm2 and a priming volume of 192.4 mL. This article describes in brief the developmental process used to advance a new filter design and supports the value of numerical modeling in this undertaking.

Mastcam Special Filters Help Locate Variations Ahead

NASA Image and Video Library

2017-11-01

This pair of images from the Mast Camera (Mastcam) on NASA's Curiosity rover illustrates how special filters are used to scout terrain ahead for variations in the local bedrock. The upper panorama is in the Mastcam's usual full color, for comparison. The lower panorama of the same scene, in false color, combines three exposures taken through different "science filters," each selecting for a narrow band of wavelengths. Filters and image processing steps were selected to make stronger signatures of hematite, an iron-oxide mineral, evident as purple. Hematite is of interest in this area of Mars -- partway up "Vera Rubin Ridge" on lower Mount Sharp -- as holding clues about ancient environmental conditions under which that mineral originated. In this pair of panoramas, the strongest indications of hematite appear related to areas where the bedrock is broken up. With information from this Mastcam reconnaissance, the rover team selected destinations in the scene for close-up investigations to gain understanding about the apparent patchiness in hematite spectral features. The Mastcam's left-eye camera took the component images of both panoramas on Sept. 12, 2017, during the 1,814th Martian day, or sol, of Curiosity's work on Mars. The view spans from south-southeast on the left to south-southwest on the right. The foreground across the bottom of the scene is about 50 feet (about 15 meters) wide. Figure 1 includes scale bars of 1 meter (3.3 feet) in the middle distance and 5 meters (16 feet) at upper right. Curiosity's Mastcam combines two cameras: the right eye with a telephoto lens and the left eye with a wider-angle lens. Each camera has a filter wheel that can be rotated in front of the lens for a choice of eight different filters. One filter for each camera is clear to all visible light, for regular full-color photos, and another is specifically for viewing the Sun. Some of the other filters were selected to admit wavelengths of light that are useful for identifying iron minerals. Each of the filters used for the lower panorama shown here admits light from a narrow band of wavelengths, extending to only about 5 to 10 nanometers longer or shorter than the filter's central wavelength. The three observations combined into this product used filters centered at three near-infrared wavelengths: 751 nanometers, 867 nanometers and 1,012 nanometers. Hematite distinctively absorbs some frequencies of infrared light more than others. Usual color photographs from digital cameras -- such as the upper panorama here from Mastcam -- combine information from red, green and blue filtering. The filters are in a microscopic grid in a "Bayer" filter array situated directly over the detector behind the lens, with wider bands of wavelengths. The colors of the upper panorama, as with most featured images from Mastcam, have been tuned with a color adjustment similar to white balancing for approximating how the rocks and sand would appear under daytime lighting conditions on Earth. https://photojournal.jpl.nasa.gov/catalog/PIA22065

An estimator-predictor approach to PLL loop filter design

NASA Technical Reports Server (NTRS)

Statman, J. I.; Hurd, W. J.

1986-01-01

An approach to the design of digital phase locked loops (DPLLs), using estimation theory concepts in the selection of a loop filter, is presented. The key concept is that the DPLL closed-loop transfer function is decomposed into an estimator and a predictor. The estimator provides recursive estimates of phase, frequency, and higher order derivatives, while the predictor compensates for the transport lag inherent in the loop. This decomposition results in a straightforward loop filter design procedure, enabling use of techniques from optimal and sub-optimal estimation theory. A design example for a particular choice of estimator is presented, followed by analysis of the associated bandwidth, gain margin, and steady state errors caused by unmodeled dynamics. This approach is under consideration for the design of the Deep Space Network (DSN) Advanced Receiver Carrier DPLL.

Technological development of spectral filters for Sentinel-2

NASA Astrophysics Data System (ADS)

Schröter, Karin; Schallenberg, Uwe; Mohaupt, Matthias

2017-11-01

In the frame of the initiative for Global Monitoring for Environment and Security (GMES), jointly undertaken by the European Commission and the European Space Agency a technological development of two filter assemblies was performed for the Multi- Spectral Instrument (MSI) for Sentinel-2. The multispectral pushbroom imaging of the Earth will be performed in 10 VNIR bands (from 443 nm to 945nm) and 3 SWIR bands (from 1375 nm to 2190 nm). Possible filter coating techniques and masking concepts were considered in the frame of trade-off studies. The selected deposition concept is based on self-blocked all-dielectric multilayer band pass filter. Band pass and blocking characteristic is deposited on the space side of a single filter substrate whereas the detector side of the substrate has an antireflective coating. The space- and detector side masking design is realized by blades integrated in the mechanical parts including the mechanical interface to the filter assembly support on the MSI focal plane. The feasibility and required performance of the VNIR Filter Assembly and SWIR Filter Assembly were successfully demonstrated by breadboarding. Extensive performance tests of spectral and optical parameters and environmental tests (radiation, vibration, shock, thermal vacuum cycling, humidity) were performed on filter stripe- and filter assembly level. The presentation will contain a detailed description of the filter assembly design and the results of the performance and environmental tests.

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.

Computational Design of Tunable UV-Vis-IR Filters Based on Silver Nanoparticle Arrays

NASA Astrophysics Data System (ADS)

Waters, Michael; Shi, Guangsha; Kioupakis, Emmanouil

We propose design strategies to develop selective optical filters in the UV-Vis-IR spectrum using the surface plasmon response of silver nanoparticle arrays. Our finite-difference time-domain simulations allow us to rapidly evaluate many nanostructures comprising simple geometries while varying their shape, height, width, and spacing. Our results allow us to identify trends in the filtering spectra as well as the relative amount of absorption and reflection. Optical filtering with nanoparticles is applicable to any transparent substrate and can be easily adapted to existing manufacturing processes while keeping the total cost of materials low. This work was supported by Guardian Industries Corp.

CLAES blocker filter rejection requirements. [Cryogenic Limb Array Etalon Spectrometer

NASA Technical Reports Server (NTRS)

James, T. C.; Kumer, J. B.; Roche, A. E.; Sterritt, L. W.; Uplinger, W. G.

1986-01-01

Some details of the calculations of out-of-band spectral rejection requirements for the CLAES blocker filters are described. For a particular blocker centered within an etalon bandpass, the signal to be expected when a particular etalon transmission peak is centered at the central wavelength of the blocker filter is calculated. This signal is compared with the total signal arising from all other transmission peaks within the etalon bandpass and all of the radiation from the entire spectrum outside of the etalon bandpass. The results for a few of the blocker filters are listed, and the design goals are compared with theoretical design results.

Combline designs improve mm-wave filter performance

NASA Astrophysics Data System (ADS)

Hey-Shipton, Gregory L.

1990-10-01

Combline filters with 2- to 75-percent bandwidths and orders up to 19 are discussed. They are realized as coupled rectangular coaxial transmission lines, since this type of transmission line is characterized by machinability and the wide variation in coupling coefficients that can be realized with rectangular bars. A broadband combline filter designed as a 19th-order, 0.01-dB equal-ripple Chebyshev type is presented, along with a third-order 0.001-dB equal-ripple Chebyshev filter with a 200-MHz bandwidth centered at 8.0 GHz. Interfaces to standard 50-ohm coaxial lines, as well as structures for waveguide interfaces are described, and focus is placed on a two-step impedance transformer matching a 538-ohm waveguide characteristic impedance to a 95-ohm filter terminal impedance.

Filtering of Discrete-Time Switched Neural Networks Ensuring Exponential Dissipative and $l_{2}$ - $l_{\\infty }$ Performances.

PubMed

Choi, Hyun Duck; Ahn, Choon Ki; Karimi, Hamid Reza; Lim, Myo Taeg

2017-10-01

This paper studies delay-dependent exponential dissipative and l 2 - l ∞ filtering problems for discrete-time switched neural networks (DSNNs) including time-delayed states. By introducing a novel discrete-time inequality, which is a discrete-time version of the continuous-time Wirtinger-type inequality, we establish new sets of linear matrix inequality (LMI) criteria such that discrete-time filtering error systems are exponentially stable with guaranteed performances in the exponential dissipative and l 2 - l ∞ senses. The design of the desired exponential dissipative and l 2 - l ∞ filters for DSNNs can be achieved by solving the proposed sets of LMI conditions. Via numerical simulation results, we show the validity of the desired discrete-time filter design approach.

Dichroic Filter for Separating W-Band and Ka-Band

NASA Technical Reports Server (NTRS)

Epp, Larry W.; Durden, Stephen L.; Jamnejad, Vahraz; Long, Ezra M.; Sosnowski, John B.; Higuera, Raymond J.; Chen, Jacqueline C.

2012-01-01

The proposed Aerosol/Cloud/Ecosystems (ACEs) mission development would advance cloud profiling radar from that used in CloudSat by adding a 35-GHz (Ka-band) channel to the 94-GHz (W-band) channel used in CloudSat. In order to illuminate a single antenna, and use CloudSat-like quasi-optical transmission lines, a spatial diplexer is needed to add the Ka-band channel. A dichroic filter separates Ka-band from W-band by employing advances in electrical discharge machining (EDM) and mode-matching analysis techniques developed and validated for designing dichroics for the Deep Space Network (DSN), to develop a preliminary design that both met the requirements of frequency separation and mechanical strength. First, a mechanical prototype was built using an approximately 102-micron-diameter EDM process, and tolerances of the hole dimensions, wall thickness, radius, and dichroic filter thickness measured. The prototype validated the manufacturing needed to design a dichroic filter for a higher-frequency usage than previously used in the DSN. The initial design was based on a Ka-band design, but thicker walls are required for mechanical rigidity than one obtains by simply scaling the Ka-band dichroic filter. The resulting trade of hole dimensions for mechanical rigidity (wall thickness) required electrical redesign of the hole dimensions. Updates to existing codes in the linear solver decreased the analysis time using mode-matching, enabling the electrical design to be realized quickly. This work is applicable to missions and instruments that seek to extend W-band cloud profiling measurements to other frequencies. By demonstrating a dichroic filter that passes W-band, but reflects a lower frequency, this opens up the development of instruments that both compare to and enhance CloudSat.

78 FR 57911 - Self-Regulatory Organizations; BOX Options Exchange LLC; Order Approving a Proposed Rule Change...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-20

... Filter September 16, 2013. I. Introduction On July 22, 2013, BOX Options Exchange LLC (the ``Exchange... included in the HSVF. A. Complex Order Filter BOX's Complex Order Filter provides a process designed to....\\4\\ BOX proposes to revise its rules to specifically provide that the Complex Order Filter operates...

Optimum design of hybrid phase locked loops

NASA Technical Reports Server (NTRS)

Lee, P.; Yan, T.

1981-01-01

The design procedure of phase locked loops is described in which the analog loop filter is replaced by a digital computer. Specific design curves are given for the step and ramp input changes in phase. It is shown that the designed digital filter depends explicitly on the product of the sampling time and the noise bandwidth of the phase locked loop. This technique of optimization can be applied to the design of digital analog loops for other applications.

Evaluation of a Cubature Kalman Filtering-Based Phase Unwrapping Method for Differential Interferograms with High Noise in Coal Mining Areas

PubMed Central

Liu, Wanli; Bian, Zhengfu; Liu, Zhenguo; Zhang, Qiuzhao

2015-01-01

Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise. PMID:26153776

Optimal filter design with progressive genetic algorithm for local damage detection in rolling bearings

NASA Astrophysics Data System (ADS)

Wodecki, Jacek; Michalak, Anna; Zimroz, Radoslaw

2018-03-01

Harsh industrial conditions present in underground mining cause a lot of difficulties for local damage detection in heavy-duty machinery. For vibration signals one of the most intuitive approaches of obtaining signal with expected properties, such as clearly visible informative features, is prefiltration with appropriately prepared filter. Design of such filter is very broad field of research on its own. In this paper authors propose a novel approach to dedicated optimal filter design using progressive genetic algorithm. Presented method is fully data-driven and requires no prior knowledge of the signal. It has been tested against a set of real and simulated data. Effectiveness of operation has been proven for both healthy and damaged case. Termination criterion for evolution process was developed, and diagnostic decision making feature has been proposed for final result determinance.

An Adaptive Kalman Filter Using a Simple Residual Tuning Method

NASA Technical Reports Server (NTRS)

Harman, Richard R.

1999-01-01

One difficulty in using Kalman filters in real world situations is the selection of the correct process noise, measurement noise, and initial state estimate and covariance. These parameters are commonly referred to as tuning parameters. Multiple methods have been developed to estimate these parameters. Most of those methods such as maximum likelihood, subspace, and observer Kalman Identification require extensive offline processing and are not suitable for real time processing. One technique, which is suitable for real time processing, is the residual tuning method. Any mismodeling of the filter tuning parameters will result in a non-white sequence for the filter measurement residuals. The residual tuning technique uses this information to estimate corrections to those tuning parameters. The actual implementation results in a set of sequential equations that run in parallel with the Kalman filter. A. H. Jazwinski developed a specialized version of this technique for estimation of process noise. Equations for the estimation of the measurement noise have also been developed. These algorithms are used to estimate the process noise and measurement noise for the Wide Field Infrared Explorer star tracker and gyro.

Correlation Filters for Detection of Cellular Nuclei in Histopathology Images.

PubMed

Ahmad, Asif; Asif, Amina; Rajpoot, Nasir; Arif, Muhammad; Minhas, Fayyaz Ul Amir Afsar

2017-11-21

Nuclei detection in histology images is an essential part of computer aided diagnosis of cancers and tumors. It is a challenging task due to diverse and complicated structures of cells. In this work, we present an automated technique for detection of cellular nuclei in hematoxylin and eosin stained histopathology images. Our proposed approach is based on kernelized correlation filters. Correlation filters have been widely used in object detection and tracking applications but their strength has not been explored in the medical imaging domain up till now. Our experimental results show that the proposed scheme gives state of the art accuracy and can learn complex nuclear morphologies. Like deep learning approaches, the proposed filters do not require engineering of image features as they can operate directly on histopathology images without significant preprocessing. However, unlike deep learning methods, the large-margin correlation filters developed in this work are interpretable, computationally efficient and do not require specialized or expensive computing hardware. A cloud based webserver of the proposed method and its python implementation can be accessed at the following URL: http://faculty.pieas.edu.pk/fayyaz/software.html#corehist .

The performance of biological anaerobic filters packed with sludge-fly ash ceramic particles (SFCP) and commercial ceramic particles (CCP) during the restart period: effect of the C/N ratios and filter media.

PubMed

Yue, Qinyan; Han, Shuxin; Yue, Min; Gao, Baoyu; Li, Qian; Yu, Hui; Zhao, Yaqin; Qi, Yuanfeng

2009-11-01

Two lab-scale upflow biological anaerobic filters (BAF) packed with sludge-fly ash ceramic particles (SFCP) and commercial ceramic particles (CCP) were employed to investigate effects of the C/N ratios and filter media on the BAF performance during the restart period. The results indicated that BAF could be restarted normally after one-month cease. The C/N ratio of 4.0 was the thresholds of nitrate removal and nitrite accumulation. TN removal and phosphate uptake reached the maximum value at the same C/N ratio of 5.5. Ammonia formation was also found and excreted a negative influence on TN removal, especially when higher C/N ratios were applied. Nutrients were mainly degraded within the height of 25 cm from the bottom. In addition, SFCP, as novel filter media manufactured by wastes-dewatered sludge and fly ash, represented a better potential in inhibiting nitrite accumulation, TN removal and phosphate uptake due to their special characteristics in comparison with CCP.

Adaptive marginal median filter for colour images.

PubMed

Morillas, Samuel; Gregori, Valentín; Sapena, Almanzor

2011-01-01

This paper describes a new filter for impulse noise reduction in colour images which is aimed at improving the noise reduction capability of the classical vector median filter. The filter is inspired by the application of a vector marginal median filtering process over a selected group of pixels in each filtering window. This selection, which is based on the vector median, along with the application of the marginal median operation constitutes an adaptive process that leads to a more robust filter design. Also, the proposed method is able to process colour images without introducing colour artifacts. Experimental results show that the images filtered with the proposed method contain less noisy pixels than those obtained through the vector median filter.

Optical Design of the LSST Camera

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

Olivier, S S; Seppala, L; Gilmore, K

2008-07-16

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design, with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a camera system that includes a set of broad-band filters and refractive corrector lenses to produce a flat focal plane with a field of view of 9.6 square degrees. Optical design of the camera lenses and filters is integrated with optical design of telescope mirrors to optimize performance, resulting in excellent image quality over the entire field from ultra-violet to near infra-red wavelengths. The LSST camera optics design consists of three refractive lenses withmore » clear aperture diameters of 1.55 m, 1.10 m and 0.69 m and six interchangeable, broad-band, filters with clear aperture diameters of 0.75 m. We describe the methodology for fabricating, coating, mounting and testing these lenses and filters, and we present the results of detailed tolerance analyses, demonstrating that the camera optics will perform to the specifications required to meet their performance goals.« less

Low-sensitivity H ∞ filter design for linear delta operator systems with sampling time jitter

NASA Astrophysics Data System (ADS)

Guo, Xiang-Gui; Yang, Guang-Hong

2012-04-01

This article is concerned with the problem of designing H ∞ filters for a class of linear discrete-time systems with low-sensitivity to sampling time jitter via delta operator approach. Delta-domain model is used to avoid the inherent numerical ill-condition resulting from the use of the standard shift-domain model at high sampling rates. Based on projection lemma in combination with the descriptor system approach often used to solve problems related to delay, a novel bounded real lemma with three slack variables for delta operator systems is presented. A sensitivity approach based on this novel lemma is proposed to mitigate the effects of sampling time jitter on system performance. Then, the problem of designing a low-sensitivity filter can be reduced to a convex optimisation problem. An important consideration in the design of correlation filters is the optimal trade-off between the standard H ∞ criterion and the sensitivity of the transfer function with respect to sampling time jitter. Finally, a numerical example demonstrating the validity of the proposed design method is given.

Progress on applications of high temperature superconducting microwave filters

NASA Astrophysics Data System (ADS)

Chunguang, Li; Xu, Wang; Jia, Wang; Liang, Sun; Yusheng, He

2017-07-01

In the past two decades, various kinds of high performance high temperature superconducting (HTS) filters have been constructed and the HTS filters and their front-end subsystems have been successfully applied in many fields. The HTS filters with small insertion loss, narrow bandwidth, flat in-band group delay, deep out-of-band rejection, and steep skirt slope are reviewed. Novel HTS filter design technologies, including those in high power handling filters, multiband filters and frequency tunable filters, are reviewed, as well as the all-HTS integrated front-end receivers. The successful applications to various civilian fields, such as mobile communication, radar, deep space detection, and satellite technology, are also reviewed.

Designing manufacturable filters for a 16-band plenoptic camera using differential evolution

NASA Astrophysics Data System (ADS)

Doster, Timothy; Olson, Colin C.; Fleet, Erin; Yetzbacher, Michael; Kanaev, Andrey; Lebow, Paul; Leathers, Robert

2017-05-01

A 16-band plenoptic camera allows for the rapid exchange of filter sets via a 4x4 filter array on the lens's front aperture. This ability to change out filters allows for an operator to quickly adapt to different locales or threat intelligence. Typically, such a system incorporates a default set of 16 equally spaced at-topped filters. Knowing the operating theater or the likely targets of interest it becomes advantageous to tune the filters. We propose using a modified beta distribution to parameterize the different possible filters and differential evolution (DE) to search over the space of possible filter designs. The modified beta distribution allows us to jointly optimize the width, taper and wavelength center of each single- or multi-pass filter in the set over a number of evolutionary steps. Further, by constraining the function parameters we can develop solutions which are not just theoretical but manufacturable. We examine two independent tasks: general spectral sensing and target detection. In the general spectral sensing task we utilize the theory of compressive sensing (CS) and find filters that generate codings which minimize the CS reconstruction error based on a fixed spectral dictionary of endmembers. For the target detection task and a set of known targets, we train the filters to optimize the separation of the background and target signature. We compare our results to the default 16 at-topped non-overlapping filter set which comes with the plenoptic camera and full hyperspectral resolution data which was previously acquired.

An optimal search filter for retrieving systematic reviews and meta-analyses

PubMed Central

2012-01-01

Background Health-evidence.ca is an online registry of systematic reviews evaluating the effectiveness of public health interventions. Extensive searching of bibliographic databases is required to keep the registry up to date. However, search filters have been developed to assist in searching the extensive amount of published literature indexed. Search filters can be designed to find literature related to a certain subject (i.e. content-specific filter) or particular study designs (i.e. methodological filter). The objective of this paper is to describe the development and validation of the health-evidence.ca Systematic Review search filter and to compare its performance to other available systematic review filters. Methods This analysis of search filters was conducted in MEDLINE, EMBASE, and CINAHL. The performance of thirty-one search filters in total was assessed. A validation data set of 219 articles indexed between January 2004 and December 2005 was used to evaluate performance on sensitivity, specificity, precision and the number needed to read for each filter. Results Nineteen of 31 search filters were effective in retrieving a high level of relevant articles (sensitivity scores greater than 85%). The majority achieved a high degree of sensitivity at the expense of precision and yielded large result sets. The main advantage of the health-evidence.ca Systematic Review search filter in comparison to the other filters was that it maintained the same level of sensitivity while reducing the number of articles that needed to be screened. Conclusions The health-evidence.ca Systematic Review search filter is a useful tool for identifying published systematic reviews, with further screening to identify those evaluating the effectiveness of public health interventions. The filter that narrows the focus saves considerable time and resources during updates of this online resource, without sacrificing sensitivity. PMID:22512835

Adaptive Deblurring of Noisy Images

DTIC Science & Technology

2007-10-01

deblurring filter adaptively by estimating energy of the signal and noise of the image to determine the passband and transition-band of the filter...The deblurring filter design criteria are: a) filter magnitude is less than one at the frequencies where the noise is stronger than the desired signal...filter is able to deblur the image by a desired amount based on the estimated or known blurring function while suppressing the noise in the output

Filter Bed of Packed Spheres

NASA Technical Reports Server (NTRS)

Elleman, D. D.; Wang, T. G.

1986-01-01

Spheres sized and treated for desired sieve properties. Filter constructed from densely packed spheres restrained by screens. Hollow gas-filled plastic or metal spheres normally used. Manufactured within one percent or better diameter tolerance. Normally, all spheres in filter of same nominal diameter. Filter used as sieve to pass only particles smaller than given size or to retain particles larger than that size. Options available under filter concept make it easy to design for specific applications.

How to include frequency dependent complex permeability Into SPICE models to improve EMI filters design?

NASA Astrophysics Data System (ADS)

Sixdenier, Fabien; Yade, Ousseynou; Martin, Christian; Bréard, Arnaud; Vollaire, Christian

2018-05-01

Electromagnetic interference (EMI) filters design is a rather difficult task where engineers have to choose adequate magnetic materials, design the magnetic circuit and choose the size and number of turns. The final design must achieve the attenuation requirements (constraints) and has to be as compact as possible (goal). Alternating current (AC) analysis is a powerful tool to predict global impedance or attenuation of any filter. However, AC analysis are generally performed without taking into account the frequency-dependent complex permeability behaviour of soft magnetic materials. That's why, we developed two frequency-dependent complex permeability models able to be included into SPICE models. After an identification process, the performances of each model are compared to measurements made on a realistic EMI filter prototype in common mode (CM) and differential mode (DM) to see the benefit of the approach. Simulation results are in good agreement with the measured ones especially in the middle frequency range.

Angular-Rate Estimation Using Delayed Quaternion Measurements

NASA Technical Reports Server (NTRS)

Azor, R.; Bar-Itzhack, I. Y.; Harman, R. R.

1999-01-01

This paper presents algorithms for estimating the angular-rate vector of satellites using quaternion measurements. Two approaches are compared one that uses differentiated quaternion measurements to yield coarse rate measurements, which are then fed into two different estimators. In the other approach the raw quaternion measurements themselves are fed directly into the two estimators. The two estimators rely on the ability to decompose the non-linear part of the rotas rotational dynamics equation of a body into a product of an angular-rate dependent matrix and the angular-rate vector itself. This non unique decomposition, enables the treatment of the nonlinear spacecraft (SC) dynamics model as a linear one and, thus, the application of a PseudoLinear Kalman Filter (PSELIKA). It also enables the application of a special Kalman filter which is based on the use of the solution of the State Dependent Algebraic Riccati Equation (SDARE) in order to compute the gain matrix and thus eliminates the need to compute recursively the filter covariance matrix. The replacement of the rotational dynamics by a simple Markov model is also examined. In this paper special consideration is given to the problem of delayed quaternion measurements. Two solutions to this problem are suggested and tested. Real Rossi X-Ray Timing Explorer (RXTE) data is used to test these algorithms, and results are presented.

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.

Application of acoustic surface wave filter-beam lead component technology to deep space multimission hardware design

NASA Technical Reports Server (NTRS)

Kermode, A. W.; Boreham, J. F.

1974-01-01

This paper discusses the utilization of acoustic surface wave filters, beam lead components, and thin film metallized ceramic substrate technology as applied to the design of deep space, long-life, multimission transponder. The specific design to be presented is for a second mixer local oscillator module, operating at frequencies as high as 249 MHz.

The Time-Domain Matched Filter and the Spectral-Domain Matched Filter in 1-Dimensional NMR Spectroscopy.

PubMed

Spencer, Richard G

2010-09-01

A type of "matched filter" (MF), used extensively in the processing of one-dimensional spectra, is defined by multiplication of a free-induction decay (FID) by a decaying exponential with the same time constant as that of the FID. This maximizes, in a sense to be defined, the signal-to-noise ratio (SNR) in the spectrum obtained after Fourier transformation. However, a different entity known also as the matched filter was introduced by van Vleck in the context of pulse detection in the 1940's and has become widely integrated into signal processing practice. These two types of matched filters appear to be quite distinct. In the NMR case, the "filter", that is, the exponential multiplication, is defined by the characteristics of, and applied to, a time domain signal in order to achieve improved SNR in the spectral domain. In signal processing, the filter is defined by the characteristics of a signal in the spectral domain, and applied in order to improve the SNR in the temporal (pulse) domain. We reconcile these two distinct implementations of the matched filter, demonstrating that the NMR "matched filter" is a special case of the matched filter more rigorously defined in the signal processing literature. In addition, two limitations in the use of the MF are highlighted. First, application of the MF distorts resonance ratios as defined by amplitudes, although not as defined by areas. Second, the MF maximizes SNR with respect to resonance amplitude, while intensities are often more appropriately defined by areas. Maximizing the SNR with respect to area requires a somewhat different approach to matched filtering.

Art in a new light: Design and assessment of illuminants to reduce photochemical degradation of works of art

NASA Astrophysics Data System (ADS)

Delgado Ramos, Monica Fabiola

The purpose of this research is to design the best lighting that will minimize long term photochemical degradation of Old Master Drawings and/or other works of art, while maintaining the patron's appreciation of the object's color and detail. The present approach is a technological refinement to the basic underlying earlier work on fluorescent lighting by W. A. Thornton, W.A. at General Electric1. Thin-film dielectric, multi-coating technology is used to create filters that eliminate ultraviolet light, near infrared light and significant unnecessary parts from the visible spectrum, thus maximizing the reduction in photochemical degradation, while maintaining optimal color rendering. Three interference filters, were designed and manufactured successfully. The filters are designated Mark 1, Mark 2, & Mark 3. In this dissertation, the filters are analyzed with regard to their performance parameters. This includes color rendering, retardation in fading or color change, beam angle effects, filter stability, perceived brightness, and visual appreciation parameters. To a high confidence level, all three filters are perceived as being indistinguishable from Unfiltered light with regard to the color confusion index parameter (CCI). Subjective assessments by tests subjects suggest the Mark 3 filter may display some distinguishability with a confidence level for distinguishability of 35% for the overall satisfaction parameter. The Mark 3 filter is the most complex three-color type spectral profile and this might be expected due to beam angle effects or departures in accuracy of color theory. Beam angle affects suggest that the Mark 1 and Mark 2 filters do not display significant color rendering aberrations due to Newton's colors interference effects, except possibly at the periphery of the broadest (55-60+°) beam angle lamps. Filtered and Unfiltered light are effectively of the same perceived brightness, though to a low confidence level, Unfiltered light might be perceived brighter. Accelerated aging studies of the filters indicate useful mean time before failures of >20 years. In fact, no failure was observed in any of the accelerated studies, The Mark 2 and Mark 3 filters were evaluated in equal-luminosity studies with regard to their effect on limiting fading of both standard fading samples such as the ISO Blue Wool series, and also other commercial pigments or stains. Within experimental error, the Mark 2 filter either slowed fading or had no effect on fading for all pigments relative to Unfiltered light and OptivexRTM filtered light, OptivexRTM being a common commercial filter used to protect works of art. Mark 3 protected in many cases, but for some pigments it was less protective than OptivexRTM filtered light. This failure is interpreted in terms of the wavelength dependence of the excess light in certain wavelength regions on an equal luminosity condition, and suggests that more subtle wavelength dependent optimizations have to be undertaken for filters which possess significant band separation.

Design of a nano-layered tunable optical filter

NASA Astrophysics Data System (ADS)

Banerjee, A.; Awasthi, S. K.; Malaviya, U.; Ojha, S. P.

2006-12-01

A novel theory to design tunable band pass filters using one-dimensional nano-photonic structures is proposed. Periodic structures consisting of different dielectrics and semiconductor materials are considered. A detailed mathematical analysis is presented to predict allowed and forbidden bands of wavelengths with variation of angle of incidence and lattice parameters. It is possible to get desired ranges of the electromagnetic spectrum filtered with this structure by changing the incidence angle of light and/or changing the value of the lattice parameters.

A Very Compact, High Speed and Rugged Acousto-Optic Tunable Filter for Wavelength Division Demultiplexing in Fiber Optic Communication Networks. Phase 1

DTIC Science & Technology

1995-06-30

Novel concepts of near-collinear/collinear acousto - optic interactions have been investigated during this SBIR Phase I program. As a result, several...new acousto - optic tunable filters have been built and tested. The program is highlighted by: (1) Design, fabrication and experimental demonstration of...a novel TeO2 near-collinear acousto - optic tunable filter has been designed, fabricated and tested. The device exhibits a 1.29 nm spectral resolution

The research of full automatic oil filtering control technology of high voltage insulating oil

NASA Astrophysics Data System (ADS)

Gong, Gangjun; Zhang, Tong; Yan, Guozeng; Zhang, Han; Chen, Zhimin; Su, Chang

2017-09-01

In this paper, the design scheme of automatic oil filter control system for transformer oil in UHV substation is summarized. The scheme specifically includes the typical double tank filter connection control method of the transformer oil of the UHV substation, which distinguishes the single port and the double port connection structure of the oil tank. Finally, the design scheme of the temperature sensor and respirator is given in detail, and the detailed evaluation and application scenarios are given for reference.

On the design of wave digital filters with low sensitivity properties.

NASA Technical Reports Server (NTRS)

Renner, K.; Gupta, S. C.

1973-01-01

The wave digital filter patterned after doubly terminated maximum available power (MAP) networks by means of the Richard's transformation has been shown to have low-coefficient-sensitivity properties. This paper examines the exact nature of the relationship between the wave-digital-filter structure and the MAP networks and how the sensitivity property arises, which permits implementation of the digital structure with a lower coefficient word length than that possible with the conventional structures. The proper design procedure is specified and the nature of the unique complementary outputs is discussed. Finally, an example is considered which illustrates the design, the conversion techniques, and the low sensitivity properties.

Computer designed compensation filters for use in radiation therapy. Master's thesis

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

Higgins, R. Jr.

1982-12-01

A computer program was written in the MUMPS language to design filters for use in cancer radiotherapy. The filter corrects for patient surface irregularities and allows homogeneous dose distribution with depth in the patient. The program does not correct for variations in the density of the patient. The program uses data available from the software in Computerized Medical Systems Inc.'s Radiation Treatment Planning package. External contours of General Electric CAT scans are made using the RTP software. The program uses the data from these external contours in designing the compensation filters. The program is written to process from 3 tomore » 31, 1cm thick, CAT scan slices. The output from the program can be in one of two different forms. The first option will drive the probe of a CMS Water Phantom in three dimensions as if it were the bit of a routing machine. Thus a routing machine constructed to run from the same output that drives the Water Phantom probe would produce a three dimensional filter mold. The second option is a listing of thicknesses for an array of aluminum blocks to filter the radiation. The size of the filter array is 10 in. by 10 in. The Printronix printer provides an array of blocks 1/2 in. by 1/2 in. with the thickness in millimeters printed inside each block.« less

Design and manufacture of super-multilayer optical filters based on PARMS technology

NASA Astrophysics Data System (ADS)

Lü, Shaobo; Wang, Ruisheng; Ma, Jing; Jiang, Chao; Mu, Jiali; Zhao, Shuaifeng; Yin, Xiaojun

2018-04-01

Three multilayer interference optical filters, including a UV band-pass, a VIS dual-band-pass and a notch filter, were designed by using Ta2O5, Nb2O5, Al2O3 and SiO2 as high- and low-index materials. During the design of the coating process, a hybrid optical monitoring and RATE-controlled layer thickness control scheme was adopted. The coating process was simulated by using the optical monitoring system (OMS) Simulator, and the simulation result indicated that the layer thickness can be controlled within an error of less than ±0.1%. The three filters were manufactured on a plasma-assisted reactive magnetic sputtering (PARMS) coating machine. The measurements indicate that for the UV band-pass filter, the peak transmittance is higher than 95% and the blocking density is better than OD6 in the 300-1100 nm region, whereas for the dual-band-pass filter, the center wavelength positioning accuracy of the two passbands are less than ±2 nm, the peak transmittance is higher than 95% and blocking density is better than OD6 in the 300-950 nm region. Finally, for the notch filter, the minimum transmittance rates are >90% and >94% in the visible and near infrared, respectively, and the blocking density is better than OD5.5 at 808 nm.

The Design, Implementation, and Performance of the Astro-H SXS Aperture Assembly and Blocking Filters

NASA Technical Reports Server (NTRS)

Kilbourne, Caroline A.; Adams, Joseph S.; Arsenovic, Petar; Ayers, Travis; Chiao, Meng P.; DiPirro, Michael J.; Eckart, Megan E.; Fujimoto, Ryuichi; Kazeva, John D.; Kelley, Richard L.;

Design, implementation, and performance of the Astro-H soft x-ray spectrometer aperture assembly and blocking filters

NASA Astrophysics Data System (ADS)

Kilbourne, Caroline A.; Adams, Joseph S.; Arsenovic, Petar; Ayers, Travis; Chiao, Meng P.; DiPirro, Michael J.; Eckart, Megan E.; Fujimoto, Ryuichi; Kazeva, John D.; Kripps, Kari L.; Lairson, Bruce M.; Leutenegger, Maurice A.; Lopez, Heidi C.; McCammon, Dan; McGuinness, Daniel S.; Mitsuda, Kazuhisa; Moseley, Samuel J.; Porter, F. Scott; Schweiss, Andrea N.; Takei, Yoh; Thorpe, Rosemary Schmidt; Watanabe, Tomomi; Yamasaki, Noriko Y.; Yoshida, Seiji

2018-01-01

The calorimeter array of the JAXA Astro-H (renamed Hitomi) soft x-ray spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV. The properties that made the SXS array a powerful x-ray spectrometer also made it sensitive to photons from the entire electromagnetic band as well as particles. If characterized as a bolometer, it would have had a noise equivalent power of <4 × 10 ? 18 W / (Hz)0.5. Thus, it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. In addition, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. These needs were addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that blocked long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly was a system of barriers, baffles, filter carriers, and filter mounts that supported the filters and inhibited their potential contamination. The three outer filters also had been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.

Ares I Flight Control System Design

NASA Technical Reports Server (NTRS)

Jang, Jiann-Woei; Alaniz, Abran; Hall, Robert; Bedrossian, Nazareth; Hall, Charles; Ryan, Stephen; Jackson, Mark

2010-01-01

The Ares I launch vehicle represents a challenging flex-body structural environment for flight control system design. This paper presents a design methodology for employing numerical optimization to develop the Ares I flight control system. The design objectives include attitude tracking accuracy and robust stability with respect to rigid body dynamics, propellant slosh, and flex. Under the assumption that the Ares I time-varying dynamics and control system can be frozen over a short period of time, the flight controllers are designed to stabilize all selected frozen-time launch control systems in the presence of parametric uncertainty. Flex filters in the flight control system are designed to minimize the flex components in the error signals before they are sent to the attitude controller. To ensure adequate response to guidance command, step response specifications are introduced as constraints in the optimization problem. Imposing these constraints minimizes performance degradation caused by the addition of the flex filters. The first stage bending filter design achieves stability by adding lag to the first structural frequency to phase stabilize the first flex mode while gain stabilizing the higher modes. The upper stage bending filter design gain stabilizes all the flex bending modes. The flight control system designs provided here have been demonstrated to provide stable first and second stage control systems in both Draper Ares Stability Analysis Tool (ASAT) and the MSFC 6DOF nonlinear time domain simulation.

Reductions of E. coli, echovirus type 12 and bacteriophages in an intermittently operated household-scale slow sand filter.

PubMed

Elliott, M A; Stauber, C E; Koksal, F; DiGiano, F A; Sobsey, M D

2008-05-01

Point-of-use (POU) drinking water treatment technology enables those without access to safe water sources to improve the quality of their water by treating it in the home. One of the most promising emerging POU technologies is the biosand filter (BSF), a household-scale, intermittently operated slow sand filter. Over 500,000 people in developing countries currently use the filters to treat their drinking water. However, despite this successful implementation, there has been almost no systematic, process engineering research to substantiate the effectiveness of the BSF or to optimize its design and operation. The major objectives of this research were to: (1) gain an understanding of the hydraulic flow condition within the filter (2) characterize the ability of the BSF to reduce the concentration of enteric bacteria and viruses in water and (3) gain insight into the key parameters of filter operation and their effects on filter performance. Three 6-8 week microbial challenge experiments are reported herein in which local surface water was seeded with E. coli, echovirus type 12 and bacteriophages (MS2 and PRD-1) and charged to the filter daily. Tracer tests indicate that the BSF operated at hydraulic conditions closely resembling plug flow. The performance of the filter in reducing microbial concentrations was highly dependent upon (1) filter ripening over weeks of operation and (2) the daily volume charged to the filter. BSF performance was best when less than one pore volume (18.3-L in the filter design studied) was charged to the filter per day and this has important implications for filter design and operation. Enhanced filter performance due to ripening was generally observed after roughly 30 days. Reductions of E. coli B ranged from 0.3 log10 (50%) to 4 log10, with geometric mean reductions after at least 30 days of operation of 1.9 log10. Echovirus 12 reductions were comparable to those for E. coli B with a range of 1 log10 to >3 log10 and mean reductions after 30 days of 2.1 log10. Bacteriophage reductions were much lower, ranging from zero to 1.3 log10 (95%) with mean reductions of only 0.5 log10 (70%). These data indicate that virus reduction by BSF may differ substantially depending upon the specific viral agent.

COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC. - INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA Science Inventory

The CPFM technology is designed to remove trace to moderate levels of nontritium radionuclides and heavy metal pollutants from water. The technology uses a proprietary compound that consists of inorganic, oxide-based granules. This mixed is designed to remove heavy metals and rad...

Design of Linear Quadratic Regulators and Kalman Filters

NASA Technical Reports Server (NTRS)

Lehtinen, B.; Geyser, L.

1986-01-01

AESOP solves problems associated with design of controls and state estimators for linear time-invariant systems. Systems considered are modeled in state-variable form by set of linear differential and algebraic equations with constant coefficients. Two key problems solved by AESOP are linear quadratic regulator (LQR) design problem and steady-state Kalman filter design problem. AESOP is interactive. User solves design problems and analyzes solutions in single interactive session. Both numerical and graphical information available to user during the session.

A 3D ultrasound scanner: real time filtering and rendering algorithms.

PubMed

Cifarelli, D; Ruggiero, C; Brusacà, M; Mazzarella, M

1997-01-01

The work described here has been carried out within a collaborative project between DIST and ESAOTE BIOMEDICA aiming to set up a new ultrasonic scanner performing 3D reconstruction. A system is being set up to process and display 3D ultrasonic data in a fast, economical and user friendly way to help the physician during diagnosis. A comparison is presented among several algorithms for digital filtering, data segmentation and rendering for real time, PC based, three-dimensional reconstruction from B-mode ultrasonic biomedical images. Several algorithms for digital filtering have been compared as relates to processing time and to final image quality. Three-dimensional data segmentation techniques and rendering has been carried out with special reference to user friendly features for foreseeable applications and reconstruction speed.

VizieR Online Data Catalog: Long-term optical monitoring of E1821+643 (Shapovalova+, 2016)

NASA Astrophysics Data System (ADS)

Shapovalova, A. I.; Popovic, L. C.; Chavushyan, V. H.; Burenkov, A. N.; Ilic, D.; Kollatschny, W.; Kovacevic, A.; Valdes, J. R.; Patino-Alvarez, V.; Leon-Tavares, J.; Torrealba, J.; Zhdanova, V. E.

2016-03-01

The photometry in BVR filters of E1821+643 was performed at the Special Astrophysical Observatory of the Russian Academy of Science (SAO RAS) during the 2003-2014 period (98 nights) with the 1m Zeiss telescope. The photometric system of this instrument resembles those of Johnson in the B and V filters and of Cousins in the R filter. Spectra of E1821+643 (~140 nights) were acquired with two telescopes (6m and 1m) at SAO RAS, Russia (during 1998-2014), one telescope (INAOE's 2.1m) at Guillermo Haro Observatory (GHO) Cananea, Sonora, Mexico (during 1998-2007 and 2013), and two telescopes (3.5m and 2.2m) at Calar Alto Observatory, Spain (during 1990-1994). (4 data files).