Analytical approach for modeling and performance analysis of microring resonators as optical filters with multiple output bus waveguides

NASA Astrophysics Data System (ADS)

Lakra, Suchita; Mandal, Sanjoy

2017-06-01

A quadruple micro-optical ring resonator (QMORR) with multiple output bus waveguides is mathematically modeled and analyzed by making use of the delay-line signal processing approach in Z-domain and Mason's gain formula. The performances of QMORR with two output bus waveguides with vertical coupling are analyzed. This proposed structure is capable of providing wider free spectral response from both the output buses with appreciable cross talk. Thus, this configuration could provide increased capacity to insert a large number of communication channels. The simulated frequency response characteristic and its dispersion and group delay characteristics are graphically presented using the MATLAB environment.

AgRISTARS. Supporting research: MARS x-band scatterometer

NASA Technical Reports Server (NTRS)

Ulaby, F. T. (Principal Investigator); Gabel, P. F., Jr.; Brunfeldt, D. R.

1981-01-01

The design, construction, and data collection procedures of the mobile agricultural radar sensor (MARS) x band scatterometer are described. This system is an inexpensive, highly mobile, truck mounted FM-CW radar operating at a center frequency of 10.2 GHz. The antennas, which allow for VV and VH polarizations, are configured in a side looking mode that allows for drive by data collection. This configuration shortens fieldwork time considerably while increasing statistical confidence in the data. Both internal calibration, via a delay line, and external calibration with a Luneberg lens are used to calibrate the instrument in terms of sigma(o). The radar scattering cross section per unit area, sigma(o), is found using the radar equation.

Surface acoustic wave devices as passive buried sensors

NASA Astrophysics Data System (ADS)

Friedt, J.-M.; Rétornaz, T.; Alzuaga, S.; Baron, T.; Martin, G.; Laroche, T.; Ballandras, S.; Griselin, M.; Simonnet, J.-P.

2011-02-01

Surface acoustic wave (SAW) devices are currently used as passive remote-controlled sensors for measuring various physical quantities through a wireless link. Among the two main classes of designs—resonator and delay line—the former has the advantage of providing narrow-band spectrum informations and hence appears compatible with an interrogation strategy complying with Industry-Scientific-Medical regulations in radio-frequency (rf) bands centered around 434, 866, or 915 MHz. Delay-line based sensors require larger bandwidths as they consists of a few interdigitated electrodes excited by short rf pulses with large instantaneous energy and short response delays but is compatible with existing equipment such as ground penetrating radar (GPR). We here demonstrate the measurement of temperature using the two configurations, particularly for long term monitoring using sensors buried in soil. Although we have demonstrated long term stability and robustness of packaged resonators and signal to noise ratio compatible with the expected application, the interrogation range (maximum 80 cm) is insufficient for most geology or geophysical purposes. We then focus on the use of delay lines, as the corresponding interrogation method is similar to the one used by GPR which allows for rf penetration distances ranging from a few meters to tens of meters and which operates in the lower rf range, depending on soil water content, permittivity, and conductivity. Assuming propagation losses in a pure dielectric medium with negligible conductivity (snow or ice), an interrogation distance of about 40 m is predicted, which overcomes the observed limits met when using interrogation methods specifically developed for wireless SAW sensors, and could partly comply with the above-mentioned applications. Although quite optimistic, this estimate is consistent with the signal to noise ratio observed during an experimental demonstration of the interrogation of a delay line buried at a depth of 5 m in snow.

Application of photonic crystal defects in constructing all-optical switches, optical delay lines and low-cross-talk waveguide intersections for ultrashort optical pulses

NASA Astrophysics Data System (ADS)

Lan, Sheng; Sugimoto, Yoshimasa; Nishikawa, Satoshi; Ikeda, Naoki; Yang, Tao; Kanamoto, Kozyo; Ishikawa, Hiroshi; Asakawa, Kiyoshi

2002-07-01

We present a systematic study of coupled defects in photonic crystals (PCs) and explore their applications in constructing optical components and devices for ultrafast all-optical signal processing. First, we find that very deep band gaps can be generated in the impurity bands of coupled cavity waveguides (CCWs) by a small periodic modulation of defect modes. This phenomenon implies a high-efficiency all-optical switching mechanism. The switching mechanism can be easily extended from one-dimensional (1D) to two-dimensional and three-dimensional PC structures by utilizing the coupling of defect pairs which are generally present in PCs. Second, we suggest that CCWs with quasiflat and narrow impurity bands can be employed as efficient delay lines for ultrashort pulses. Criteria for designing such kind of CCWs have been derived from the analysis of defect coupling and the investigation of pulse transmission through various CCWs. It is found that the availability of quasiflat impurity bands depends not only on the intrinsic properties of the constituting defects but also on the detailed configuration of CCWs. In experiments, optical delay lines based on 1D monorail CCWs have been successfully fabricated and characterized. Finally, we have proposed a new mechanism for constructing waveguide intersections with broad bandwidth and low cross-talk.

Shale oil recovery process

DOEpatents

Zerga, Daniel P.

1980-01-01

A process of producing within a subterranean oil shale deposit a retort chamber containing permeable fragmented material wherein a series of explosive charges are emplaced in the deposit in a particular configuration comprising an initiating round which functions to produce an upward flexure of the overburden and to initiate fragmentation of the oil shale within the area of the retort chamber to be formed, the initiating round being followed in a predetermined time sequence by retreating lines of emplaced charges developing further fragmentation within the retort zone and continued lateral upward flexure of the overburden. The initiating round is characterized by a plurality of 5-spot patterns and the retreating lines of charges are positioned and fired along zigzag lines generally forming retreating rows of W's. Particular time delays in the firing of successive charges are disclosed.

Inspection logistics planning for multi-stage production systems with applications to semiconductor fabrication lines

NASA Astrophysics Data System (ADS)

Chen, Kyle Dakai

Since the market for semiconductor products has become more lucrative and competitive, research into improving yields for semiconductor fabrication lines has lately received a tremendous amount of attention. One of the most critical tasks in achieving such yield improvements is to plan the in-line inspection sampling efficiently so that any potential yield problems can be detected early and eliminated quickly. We formulate a multi-stage inspection planning model based on configurations in actual semiconductor fabrication lines, specifically taking into account both the capacity constraint and the congestion effects at the inspection station. We propose a new mixed First-Come-First-Serve (FCFS) and Last-Come-First-Serve (LCFS) discipline for serving the inspection samples to expedite the detection of potential yield problems. Employing this mixed FCFS and LCFS discipline, we derive approximate expressions for the queueing delays in yield problem detection time and develop near-optimal algorithms to obtain the inspection logistics planning policies. We also investigate the queueing performance with this mixed type of service discipline under different assumptions and configurations. In addition, we conduct numerical tests and generate managerial insights based on input data from actual semiconductor fabrication lines. To the best of our knowledge, this research is novel in developing, for the first time in the literature, near-optimal results for inspection logistics planning in multi-stage production systems with congestion effects explicitly considered.

Signal enhancement of neutral He emission lines by fast electron bombardment of laser-induced He plasma

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

Suyanto, Hery; Pardede, Marincan; Hedwig, Rinda

2016-08-15

A time-resolved spectroscopic study is performed on the enhancement signals of He gas plasma emission using nanosecond (ns) and picosecond (ps) lasers in an orthogonal configuration. The ns laser is used for the He gas plasma generation and the ps laser is employed for the ejection of fast electrons from a metal target, which serves to excite subsequently the He atoms in the plasma. The study is focused on the most dominant He I 587.6 nm and He I 667.8 nm emission lines suggested to be responsible for the He-assisted excitation (HAE) mechanism. The time-dependent intensity enhancements induced by themore » fast electrons generated with a series of delayed ps laser ablations are deduced from the intensity time profiles of both He emission lines. The results clearly lead to the conclusion that the metastable excited triplet He atoms are actually the species overwhelmingly produced during the recombination process in the ns laser-induced He gas plasma. These metastable He atoms are believed to serve as the major energy source for the delayed excitation of analyte atoms in ns laser-induced breakdown spectroscopy (LIBS) using He ambient gas.« less

MAJOR ELECTRON EVENTS AND CORONAL MAGNETIC CONFIGURATIONS OF THE RELATED SOLAR ACTIVE REGIONS

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

Li, C.; Owen, C. J.; Matthews, S. A.

A statistical survey of 26 major electron events during the period 2002 February through the end of solar cycle 23 is presented. We have obtained electron solar onset times and the peak flux spectra for each event by fitting to a power-law spectrum truncated by an exponential high-energy tail, i.e., f(E){approx}E{sup -{delta}}e{sup -E/E{sub 0}}. We also derived the coronal magnetic configurations of the related solar active regions (ARs) from the potential-field source-surface model. It is found that (1) 10 of the 11 well-connected open field-line events are prompt events whose solar onset times coincide with the maxima of flare emissionmore » and 13 of the 14 closed field-line events are delayed events. (2) A not-well-connected open field-line event and one of the closed field-line events are prompt events, they are both associated with large-scale coronal disturbances or dimming. (3) An averaged harder spectrum is found in open field-line events compared with the closed ones. Specifically, the averaged spectral index {delta} is of 1.6 {+-} 0.3 in open field-line events and of 2.0 {+-} 0.4 in closed ones. The spectra of three closed field-line events show infinite rollover energies E {sub 0}. These correlations clearly establish a significant link between the coronal magnetic field-line topology and the escape of charged particles from the flaring ARs into interplanetary space during the major solar energetic particle events.« less

Electrical delay line multiplexing for pulsed mode radiation detectors

NASA Astrophysics Data System (ADS)

Vinke, Ruud; Yeom, Jung Yeol; Levin, Craig S.

2015-04-01

Medical imaging systems are composed of a large number of position sensitive radiation detectors to provide high resolution imaging. For example, whole-body Positron Emission Tomography (PET) systems are typically composed of thousands of scintillation crystal elements, which are coupled to photosensors. Thus, PET systems greatly benefit from methods to reduce the number of data acquisition channels, in order to reduce the system development cost and complexity. In this paper we present an electrical delay line multiplexing scheme that can significantly reduce the number of readout channels, while preserving the signal integrity required for good time resolution performance. We experimented with two 4 × 4 LYSO crystal arrays, with crystal elements having 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm dimensions, coupled to 16 Hamamatsu MPPC S10931-050P SiPM elements. Results show that each crystal could be accurately identified, even in the presence of scintillation light sharing and inter-crystal Compton scatter among neighboring crystal elements. The multiplexing configuration degraded the coincidence timing resolution from ∼243 ps FWHM to ∼272 ps FWHM when 16 SiPM signals were combined into a single channel for the 4 × 4 LYSO crystal array with 3 mm × 3 mm × 20 mm crystal element dimensions, in coincidence with a 3 mm × 3 mm × 5 mm LYSO crystal pixel. The method is flexible to allow multiplexing configurations across different block detectors, and is scalable to an entire ring of detectors.

Advanced Photon Counting Imaging Detectors with 100ps Timing for Astronomical and Space Sensing Applications

NASA Astrophysics Data System (ADS)

Siegmund, O.; Vallerga, J.; Welsh, B.; Rabin, M.; Bloch, J.

In recent years EAG has implemented a variety of high-resolution, large format, photon-counting MCP detectors in space instrumentation for satellite FUSE, GALEX, IMAGE, SOHO, HST-COS, rocket, and shuttle payloads. Our scheme of choice has been delay line readouts encoding photon event position centroids, by determination of the difference in arrival time of the event charge at the two ends of a distributed resistive-capacitive (RC) delay line. Our most commonly used delay line configuration is the cross delay line (XDL). In its simplest form the delay-line encoding electronics consists of a fast amplifier for each end of the delay line, followed by time-to-digital converters (TDC's). We have achieved resolutions of < 25 μm in tests over 65 mm x 65 mm (3k x3k resolution elements) with excellent linearity. Using high speed TDC's, we have been able to encode event positions for random photon rates of ~1 MHz, while time tagging events using the MCP output signal to better than 100 ps. The unique ability to record photon X,Y,T high fidelity information has advantages over "frame driven" recording devices for some important applications. For example we have built open face and sealed tube cross delay line detectors used for biological fluorescence lifetime imaging, observation of flare stars, orbital satellites and space debris with the GALEX satellite, and time resolved imaging of the Crab Pulsar with a telescope as small as 1m. Although microchannel plate delay line detectors meet many of the imaging and timing demands of various applications, they have limitations. The relatively high gain (107) reduces lifetime and local counting rate, and the fixed delay (10's of ns) makes multiple simultaneous event recording problematic. To overcome these limitations we have begun development of cross strip readout anodes for microchannel plate detectors. The cross strip (XS) anode is a coarse (~0.5 mm) multi-layer metal and ceramic pattern of crossed fingers on an alumina substrate. The charge cloud is matched to the anode period so that it is collected on several neighboring fingers to ensure an accurate event charge centroid can be determined. Each finger of the anode is connected to a low noise charge sensitive amplifier and followed by subsequent A/D conversion of individual strip charge values and a hardware centroid determination of better than 1/100 of a strip are possible. Recently we have commissioned a full 32 x 32 mm XS open face laboratory detector and demonstrated excellent resolution (<6 μm FWHM, ~5k x 5k resolution) using low MCP gain (<5 x 105) thus increasing the MCP local counting rate capacity and overall lifetime of the detector system. In collaboration with Los Alamos National Laboratory, NASA and NSF we are developing high rate (>107 Hz) XS encoding electronics that will encode temporally simultaneous events (non spatially overlapping). Sealed tube XS detectors with GaAs and other photocathodes are also under development to increase detection efficiency and extend the sensitivity range. This type of sensor could be a significant enabling technology for several important applications, including airborne and space situational awareness, high-speed adaptive optics (by increasing the SNR and speed in the control loop), astronomy of transient and time-variable sources, optical metrology, and secure quantum communication (as a receiver of cryptographic keys for three-dimensional imaging), single-molecule fluorescence lifetime microscopy (simultaneously tracking and measuring ~1000 molecules), optical/NIR LIDAR, hybrid mass spectrometry and optical night-time/reconnaissance (LANL-ASPIRE).

Acoustic method of investigating the material properties and humidity sensing behavior of polymer coated piezoelectric substrates

NASA Astrophysics Data System (ADS)

Caliendo, Cinzia

2006-09-01

The relative humidity (RH) sensing behavior of a polymeric film was investigated by means of polymer coated surface acoustic wave (SAW) delay lines implemented on single crystal piezoelectric substrates, such as quartz and LiNbO3, and on thin piezoelectric polycrystalline films, such as ZnO and AlN, on Si and GaAs. The same SAW delay line configuration was implemented on each substrate and the obtained devices' operating frequency was in the range of 105-156MHz, depending on the type of the substrate, on its crystallographic orientation, and on the SAW propagation direction. The surface of each SAW device was covered by the same type RH sensitive film of the same thickness and the RH sensitivity of each polymer coated substrate, i.e., the SAW relative phase velocity shift per RH unit changes, was investigated in the 0%—80% RH range. The perturbational approach was used to relate the SAW sensor velocity response to the RH induced changes in the physical parameters of the sensitive polymer film: the incremental change in the mass density and shear modulus of the polymer film per unit RH change were estimated. The shift of the bare SAW delay lines operating frequency induced by the presence of the polymer film, at RH =0% and at T =-10°C, allowed the experimental estimation of the mass sensitivity values of each substrate. These values were in good accordance with those reported in the literature and with those theoretically evaluated by exact numerical calculation. The shift of the bare SAW delay lines propagation loss induced by the polymer coating of the device surface, at RH =0% and at ambient temperature, allowed the experimental estimation of the elastic sensitivity of each substrate. These values were found in good accordance with those available from the literature. The temperature coefficient of delay and the electromechanical coupling coefficient of the bare substrates were also estimated. The membrane sensitivity to ethanol, methanol and isopropylic alcohol was tested by means of a high-frequency (670MHz) high-sensitivity Si /AlN resonator sensor.

Apparatus and Method for Compensating for Process, Voltage, and Temperature Variation of the Time Delay of a Digital Delay Line

NASA Technical Reports Server (NTRS)

Seefeldt, James (Inventor); Feng, Xiaoxin (Inventor); Roper, Weston (Inventor)

2013-01-01

A process, voltage, and temperature (PVT) compensation circuit and a method of continuously generating a delay measure are provided. The compensation circuit includes two delay lines, each delay line providing a delay output. The two delay lines may each include a number of delay elements, which in turn may include one or more current-starved inverters. The number of delay lines may differ between the two delay lines. The delay outputs are provided to a combining circuit that determines an offset pulse based on the two delay outputs and then averages the voltage of the offset pulse to determine a delay measure. The delay measure may be one or more currents or voltages indicating an amount of PVT compensation to apply to input or output signals of an application circuit, such as a memory-bus driver, dynamic random access memory (DRAM), a synchronous DRAM, a processor or other clocked circuit.

Investigation of Various Surface Acoustic Wave Design Configurations for Improved Sensitivity

NASA Astrophysics Data System (ADS)

Manohar, Greeshma

Surface acoustic wave sensors have been a focus of active research for many years. Its ability to respond for surface perturbation is a basic principle for its sensing capability. Sensitivity to surface perturbation changes with every inter-digital transducer (IDT) design parameters, substrate selection, metallization choice and technique, delay line length and working environment. In this thesis, surface acoustic wave (SAW) sensors are designed and characterized to improve sensitivity and reduce loss. To quantify the improvements with a specific design configuration, the sensors are employed to measure temperature. Four SAW sensors design configurations, namely bi-directional, split electrode, single phase unidirectional transducer (SPUDT) and metal grating on delay line (shear transvers wave sensors) are designed and then fabricated in Nanotechnology Research and Education Center (NREC) facility using traditional MEMS fabrication processes Additionally, sensors are then coated with guiding layer SU8-2035 of 40µm using spin coating and SiO 2 of 6µm using plasma enhanced chemical vapor deposition (PECVD) process. Sensors are later diced and tested for every 5°C increment using network analyzer for temperature ranging from 30°C±0.5°C to 80°C±0.5°C. Data acquired from network analyzer is analyzed using plot of logarithmic magnitude, phase and frequency shift. Furthermore, to investigate the effect of metallization technique on the sensor performance, sensors are also fabricated on substrates that were metallized at a commercial MEMS foundry. All in-house and outside sputtered sensor configurations are compared to investigate quality of sputtered metal on wafer. One with better quality sputtered metal is chosen for further study. Later sensors coated with SU8 and SiO2 as guiding layer are compared to investigate effect of each waveguide on sensors and determine which waveguide offers better performance. The results showed that company sputtered sensors have higher sensitivity compared to in-house sputtered wafers. Furthermore after comparing SU8 and SiO2 coated sensors in the same instrumental and environmental condition, it was observed that SU8 coated di-directional and single phase unidirectional transducer (SPUDT) sensors showed best response.

A review on high-resolution CMOS delay lines: towards sub-picosecond jitter performance.

PubMed

Abdulrazzaq, Bilal I; Abdul Halin, Izhal; Kawahito, Shoji; Sidek, Roslina M; Shafie, Suhaidi; Yunus, Nurul Amziah Md

2016-01-01

A review on CMOS delay lines with a focus on the most frequently used techniques for high-resolution delay step is presented. The primary types, specifications, delay circuits, and operating principles are presented. The delay circuits reported in this paper are used for delaying digital inputs and clock signals. The most common analog and digitally-controlled delay elements topologies are presented, focusing on the main delay-tuning strategies. IC variables, namely, process, supply voltage, temperature, and noise sources that affect delay resolution through timing jitter are discussed. The design specifications of these delay elements are also discussed and compared for the common delay line circuits. As a result, the main findings of this paper are highlighting and discussing the followings: the most efficient high-resolution delay line techniques, the trade-off challenge found between CMOS delay lines designed using either analog or digitally-controlled delay elements, the trade-off challenge between delay resolution and delay range and the proposed solutions for this challenge, and how CMOS technology scaling can affect the performance of CMOS delay lines. Moreover, the current trends and efforts used in order to generate output delayed signal with low jitter in the sub-picosecond range are presented.

Autonomous Mission Operations

NASA Technical Reports Server (NTRS)

Frank, Jeremy; Spirkovska, Lilijana; McCann, Rob; Wang, Lui; Pohlkamp, Kara; Morin, Lee

2012-01-01

NASA's Advanced Exploration Systems Autonomous Mission Operations (AMO) project conducted an empirical investigation of the impact of time-delay on todays mission operations, and of the effect of processes and mission support tools designed to mitigate time-delay related impacts. Mission operation scenarios were designed for NASA's Deep Space Habitat (DSH), an analog spacecraft habitat, covering a range of activities including nominal objectives, DSH system failures, and crew medical emergencies. The scenarios were simulated at time-delay values representative of Lunar (1.2-5 sec), Near Earth Object (NEO) (50 sec) and Mars (300 sec) missions. Each combination of operational scenario and time-delay was tested in a Baseline configuration, designed to reflect present-day operations of the International Space Station, and a Mitigation configuration in which a variety of software tools, information displays, and crew-ground communications protocols were employed to assist both crews and Flight Control Team (FCT) members with the long-delay conditions. Preliminary findings indicate: 1) Workload of both crew members and FCT members generally increased along with increasing time delay. 2) Advanced procedure execution viewers, caution and warning tools, and communications protocols such as text messaging decreased the workload of both flight controllers and crew, and decreased the difficulty of coordinating activities. 3) Whereas crew workload ratings increased between 50 sec and 300 sec of time-delay in the Baseline configuration, workload ratings decreased (or remained flat) in the Mitigation configuration.

Enhancing the sensitivity of three-axis detectable surface acoustic wave gyroscope by using a floating thin piezoelectric membrane

NASA Astrophysics Data System (ADS)

Lee, Munhwan; Lee, Keekeun

2017-06-01

A new type of surface acoustic wave (SAW) gyroscope was developed on a floating thin piezoelectric membrane to enhance sensitivity and reliability by removing a bulk noise effect and by importing a higher amplitude of SAW. The developed device constitutes a two-port SAW resonator with a metallic dot array between two interdigital transducers (IDTs), and a one-port SAW delay line. The bulk silicon was completely etched away, leaving only a thin piezoelectric membrane with a thickness of one wavelength. A voltage controlled oscillator (VCO) was connected to a SAW resonator to activate the SAW resonator, while the SAW delay line was connected to the oscilloscope to monitor any variations caused by the Coriolis force. When the device was rotated, a secondary wave was generated, changing the amplitude of the SAW delay line. The highest sensitivity was observed in a device with a full acoustic wavelength thickness of the membrane because most of the acoustic field is confined within an acoustic wavelength thickness from the top surface; moreover, the thin-membrane-based gyroscope eliminates the bulk noise effect flowing along the bulk substrate. The obtained sensitivity and linearity of the SAW gyroscope were ˜27.5 µV deg-1 s-1 and ˜4.3%, respectively. Superior directivity was observed. The device surface was vacuum-sealed using poly(dimethylsiloxane) (PDMS) bonding to eliminate environmental interference. A three-axis detectable gyroscope was also implemented by placing three gyrosensors with the same configuration at right angles to each other on a printed circuit board.

Impact of backreflections on single-fiber bidirectional wavelength-division-multiplexing passive optical networks (WDM-PONs)

NASA Astrophysics Data System (ADS)

Gao, Shiyu

With increased demand for bandwidth-hungry applications such as video-on-demand, wavelength-division-multiplexing passive optical network (WDM-PON) has become a strong contender in overcoming the last mile bottle neck. However, the wide-scale deployment of WDM-PONs has been delayed mainly due to the high cost of wavelength-specific optical components. To realize cost-effective WDM-PONs, various wavelength-independent, so called colorless architectures, have been developed so that all the subscribers can have identical optical network units (ONUs). In such WDM-PONs, however, single-fiber bidirectional transmission results in degradation of system performance caused by interference between the signals and backreflections. This thesis investigates the impact of backreflections on single-fiber bidirectional WDM-PONs. A WDM-PON with various optical line terminals (OLTs) and colorless ONU configurations is presented. The dependence of the power penalty, caused by backreflections, on a variety of parameters is investigated. This includes parameters such as the source linewidths, receiver bandwidth, transmission line loss (TLL), ONU gain, chirp effect at the ONU and optical return loss (ORL), in various WDM-PON configurations. The WDM-PON with continuous wave (CW) seed light and remodulation schemes are both presented and studied experimentally. The impacts of the backreflections on the single-fiber bidirectional WDM-PON with various OLT and ONU configurations are compared and analyzed accordingly.

Comparing Methods for Dynamic Airspace Configuration

NASA Technical Reports Server (NTRS)

Zelinski, Shannon; Lai, Chok Fung

2011-01-01

This paper compares airspace design solutions for dynamically reconfiguring airspace in response to nominal daily traffic volume fluctuation. Airspace designs from seven algorithmic methods and a representation of current day operations in Kansas City Center were simulated with two times today's demand traffic. A three-configuration scenario was used to represent current day operations. Algorithms used projected unimpeded flight tracks to design initial 24-hour plans to switch between three configurations at predetermined reconfiguration times. At each reconfiguration time, algorithms used updated projected flight tracks to update the subsequent planned configurations. Compared to the baseline, most airspace design methods reduced delay and increased reconfiguration complexity, with similar traffic pattern complexity results. Design updates enabled several methods to as much as half the delay from their original designs. Freeform design methods reduced delay and increased reconfiguration complexity the most.

All-fiber variable optical delay line for applications in optical coherence tomography: feasibility study for a novel delay line.

PubMed

Choi, Eunseo; Na, Jihoon; Ryu, Seon; Mudhana, Gopinath; Lee, Byeong

2005-02-21

We have implemented an all-fiber optical delay line using two linearly chirped fiber Bragg gratings cascaded in reverse order and all-fiber optics components. The features of the proposed all-fiber based technique for variable delay line are discussed theoretically and demonstrated experimentally. The non-invasive cross-sectional images of biomedical samples as well as a transparent glass plate obtained with implemented all-fiber delay line having the axial resolution of 100 mum and the dynamic range of 50dB are presented to validates the imaging performance and demonstrate the feasibility of the delay line for optical coherence tomography.

Micromachined silicon acoustic delay line with improved structural stability and acoustic directivity for real-time photoacoustic tomography

NASA Astrophysics Data System (ADS)

Cho, Young; Kumar, Akhil; Xu, Song; Zou, Jun

2017-03-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. However, as its length increases to provide longer delay time, the delay line becomes more vulnerable to structural instability due to reduced mechanical stiffness. In addition, the small cross-section area of the delay line results in a large acoustic acceptance angle and therefore poor directivity. To address these two issues, this paper reports the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, a new tapered design for the input terminal of the delay line was also investigate to improve its acoustic directivity by reducing the acoustic acceptance angle. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

Micromachined silicon acoustic delay line with 3D-printed micro linkers and tapered input for improved structural stability and acoustic directivity

NASA Astrophysics Data System (ADS)

Cho, Y.; Kumar, A.; Xu, S.; Zou, J.

2016-10-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. To achieve deeper imaging depth and wider field of view, a longer delay time and therefore delay length are required. However, as the length of the delay line increases, it becomes more vulnerable to structural instability due to reduced mechanical stiffness. In this paper, we report the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, the improvement of the acoustic acceptance angle of the silicon acoustic delay lines was also investigated to better suppress the reception of unwanted ultrasound signals outside of the imaging plane. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

VARIABLE TIME DELAY MEANS

DOEpatents

Clemensen, R.E.

1959-11-01

An electrically variable time delay line is described which may be readily controlled simuitaneously with variable impedance matching means coupied thereto such that reflections are prevented. Broadly, the delay line includes a signal winding about a magnetic core whose permeability is electrically variable. Inasmuch as the inductance of the line varies directly with the permeability, the time delay and characteristic impedance of the line both vary as the square root of the permeability. Consequently, impedance matching means may be varied similariy and simultaneously w:th the electrically variable permeability to match the line impedance over the entire range of time delay whereby reflections are prevented.

Enhancement of the NMSU Channel Error Simulator to Provide User-Selectable Link Delays

NASA Technical Reports Server (NTRS)

Horan, Stephen; Wang, Ru-Hai

2000-01-01

This is the third in a continuing series of reports describing the development of the Space-to-Ground Link Simulator (SGLS) to be used for testing data transfers under simulated space channel conditions. The SGLS is based upon Virtual Instrument (VI) software techniques for managing the error generation, link data rate configuration, and, now, selection of the link delay value. In this report we detail the changes that needed to be made to the SGLS VI configuration to permit link delays to be added to the basic error generation and link data rate control capabilities. This was accomplished by modifying the rate-splitting VIs to include a buffer the hold the incoming data for the duration selected by the user to emulate the channel link delay. In sample tests of this configuration, the TCP/IP(sub ftp) service and the SCPS(sub fp) service were used to transmit 10-KB data files using both symmetric (both forward and return links set to 115200 bps) and unsymmetric (forward link set at 2400 bps and a return link set at 115200 bps) link configurations. Transmission times were recorded at bit error rates of 0 through 10(exp -5) to give an indication of the link performance. In these tests. we noted separate timings for the protocol setup time to initiate the file transfer and the variation in the actual file transfer time caused by channel errors. Both protocols showed similar performance to that seen earlier for the symmetric and unsymmetric channels. This time, the delays in establishing the file protocol also showed that these delays could double the transmission time and need to be accounted for in mission planning. Both protocols also showed a difficulty in transmitting large data files over large link delays. In these tests, there was no clear favorite between the TCP/IP(sub ftp) and the SCPS(sub fp). Based upon these tests, further testing is recommended to extend the results to different file transfer configurations.

Terrestrial Planet Finder cryogenic delay line development

NASA Technical Reports Server (NTRS)

Smythe, Robert F.; Swain, Mark R.; Alvarez-Salazar, Oscar; Moore, James D.

2004-01-01

Delay lines provide the path-length compensation that makes the measurement of interference fringes possible. When used for nulling interferometry, the delay line must control path-lengths so that the null is stable and controlled throughout the measurement. We report on a low noise, low disturbance, and high bandwidth optical delay line capable of meeting the TPF interferometer optical path length control requirements at cryogenic temperatures.

AGN Space Telescope and Optical Reverberation Mapping Project. IV. Velocity-Delay Mapping of Broad Emission Lines in NGC 5548

NASA Astrophysics Data System (ADS)

Horne, Keith D.; Agn Storm Team

2015-01-01

Two-dimensional velocity-delay maps of AGN broad emission line regions can be recovered by modelling observations of reverberating emission-line profiles on the assumption that the line profile variations are driven by changes in ionising radiation from a compact source near the black hole. The observable light travel time delay resolves spatial structure on iso-delay paraboloids, while the doppler shift resolves kinematic structure along the observer's line-of-sight. Velocity-delay maps will be presented and briefly discussed for the Lyman alpha, CIV and Hbeta line profiles based on the HST and ground-based spectrophotometric monitoring of NGC 5548 during the 2014 AGN STORM campaign.

ESO and Fokker Space Sign Contract about VLTI Delay Line

NASA Astrophysics Data System (ADS)

1998-03-01

The European Southern Observatory is building the world's largest optical telescope, the Very Large Telescope (VLT) , at the ESO Paranal Observatory in Chile. The VLT consists of four 8.2-m unit telescopes and several smaller, moveable Auxiliary Telescopes. When coupled as the giant VLT Interferometer (VLTI) , they will together provide the sharpest images ever obtained by any optical telescope. It will in principle be able to see an astronaut on the surface of the Moon, 400,000 km away. The VLTI Delay Lines Fokker Space (Leiden, The Netherlands) has been awarded a contract for the delivery of the Delay Line of the VLTI. This is a mechanical-optical system that will compensate the optical path differences of the light beams from the individual telescopes. Such a system is necessary to ensure that the light from all telescopes arrive in the same phase at the focal point of the interferometer. Otherwise, the very sharp interferometric images cannot be obtained. ESO PR Photo 08/98 [JPEG, 102k] Schematic representation of the VLTI Delay Line, showing the retro-reflector on its moving base. For more details, please consult the technical explanation below. This highly accurate system will be developed in close co-operation with the Dutch institute TNO-TPD (Netherlands Organization for Applied Scientific Research - Institute of Applied Physics) . The most innovative feature of the Delay Line is the new control strategy, a two-stage control system, based on linear motor technology, combined with high accuracy piezo-electric control elements. This enables the system to position the so-called cat's eye reflector system with an accuracy of only a few nanometers (millionth of a millimetre (nm)) over a stroke length of 60 metres. Within radio astronomy, interferometric techniques have been applied by Dutch astronomers since many years. They will now be able to contribute with their extensive knowledge of such systems to the next generation of astronomical interferometric instruments within the present collaboration. About Fokker Space Fokker Space is the largest company in the Dutch space industry. It is based in Leiden, has 481 employees and an operating income of 220 million Netherlands Guilders in 1996. Fokker Space is mainly active in the field of solar arrays, launcher structures, thermal products, instruments and simulators. It also plays a key role in the development of robotics and is responsible as a prime contractor for the European Robotics Arm (ERA) to be used on the International Space Station. Fokker Space is well embedded in the Dutch aerospace infrastructure, thanks to close relations with the Dutch Space Agency (NIVR) , the National Aerospace Laboratory (NLR) , the Delft University of Technology and other Dutch space industries and institutes like TNO-TPD (Netherlands Organization for Applied Scientific Research - Institute of Applied Physics) . Fokker Space has also entered into strategic partnerships in Europe, Russia and North America. These facts, combined with the long lasting relation with the European Space Agency ESA and with the Dutch Government imply that Fokker Space has secured a solid base for continuation of its business far into the next millennium. Some technical details about the VLTI Delay Line The VLT Delay Line forms an essential part of the VLT Interferometer (VLTI) . It represents the current limit of high technology in this field and includes many innovative features. Some of the technical details are given below. In order to enable a useful combination of the light beams from the individual telescopes of the VLT (that is, to produce interferometric fringes at the focal point), the optical path length differences must be corrected by the Delay Line system. These differences are caused by: * the static geometric path length difference between the telescopes in a certain configuration; * the diurnal motion of the astronomical source during observation due to Earth's rotation; and * the rapid path length variations due to atmospheric disturbances and/or mechanical vibrations along the optical path length. The VLTI Delay Line system consists of a retro-reflector mounted on a moving base. The optical design of this `Cat's Eye' is of the Ritchey-Chretien type that reflects the light very effectively. For this particular application, the `Cat's Eye' is not a corner cube with 3 perpendicular mirrors as is the case in the reflectors on cars and bicycles; it is in fact a telescope with a mirror at the focus that sends a light beam back in a direction parallel to the one it came from. The moving base enables the Cat's Eye to travel along a 60 metres long rail track, thereby providing optical path difference corrections of up to 120 metres, as required for the VLT telescope configurations at Paranal. The necessary, rapid path length corrections are performed by a fine positioning loop in which a piezo crystal (mounted on the backside of the Variable Curvature Mirror M3) is used to correct the fast optical path variations as measured by a Fringe Sensing Unit (FSU). The latter provides a signal to the Delay Line system via a fast link to the Delay Line Local Control Unit. An optical datalink to the Cat's Eye on the carriage ensures the transfer of data to the Piezo controller. The carriage is driven by a Linear Induction Motor. The coils for the motor are mounted on the floor of the Delay Line Long Support Bench and the magnets are mounted on the bottom of the carriage. The metrology system (to measure the carriage position) consists of a laser-interferometer whose beam follows the same path as the light beams from the telescopes via the Cat's Eye. The main design parameters are shown here: Optical Path range above 120 m Optical Path resolution better than 20 nm Optical Path stability better than 14 nm over any 0.01 sec (in the visible spectral range) better than 50 nm over any 0.05 sec (in Near-IR spectral range) better than 225 nm over any 0.3 sec (in Thermal-IR spectral range) Absolute position repeatability 50 micron (over full length - 60 metres) 1 micron (over observation length - 3 metres) Maximum velocity: 0.5 m/sec Maximum velocity errors 1 micron/sec Maximum power dissipation 15 Watts Note: [1] This Press Release is issued jointly by ESO and Fokker Space on the occasion of the signature of the contract for the VLTI Delay System which takes place at Fokker Space in Leiden (The Netherlands) today. How to obtain ESO Press Information ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org ). ESO Press Photos may be reproduced, if credit is given to the European Southern Observatory.

Holistic Facial Composite Creation and Subsequent Video Line-up Eyewitness Identification Paradigm.

PubMed

Davis, Josh P; Maigut, Andreea C; Jolliffe, Darrick; Gibson, Stuart J; Solomon, Chris J

2015-12-24

The paradigm detailed in this manuscript describes an applied experimental method based on real police investigations during which an eyewitness or victim to a crime may create from memory a holistic facial composite of the culprit with the assistance of a police operator. The aim is that the composite is recognized by someone who believes that they know the culprit. For this paradigm, participants view a culprit actor on video and following a delay, participant-witnesses construct a holistic system facial composite. Controls do not construct a composite. From a series of arrays of computer-generated, but realistic faces, the holistic system construction method primarily requires participant-witnesses to select the facial images most closely meeting their memory of the culprit. Variation between faces in successive arrays is reduced until ideally the final image possesses a close likeness to the culprit. Participant-witness directed tools can also alter facial features, configurations between features and holistic properties (e.g., age, distinctiveness, skin tone), all within a whole face context. The procedure is designed to closely match the holistic manner by which humans' process faces. On completion, based on their memory of the culprit, ratings of composite-culprit similarity are collected from the participant-witnesses. Similar ratings are collected from culprit-acquaintance assessors, as a marker of composite recognition likelihood. Following a further delay, all participants--including the controls--attempt to identify the culprit in either a culprit-present or culprit-absent video line-up, to replicate circumstances in which the police have located the correct culprit, or an innocent suspect. Data of control and participant-witness line-up outcomes are presented, demonstrating the positive influence of holistic composite construction on identification accuracy. Correlational analyses are conducted to measure the relationship between assessor and participant-witness composite-culprit similarity ratings, delay, identification accuracy, and confidence to examine which factors influence video line-up outcomes.

Holistic Facial Composite Creation and Subsequent Video Line-up Eyewitness Identification Paradigm

PubMed Central

Davis, Josh P.; Maigut, Andreea C.; Jolliffe, Darrick; Gibson, Stuart J.; Solomon, Chris J.

2015-01-01

The paradigm detailed in this manuscript describes an applied experimental method based on real police investigations during which an eyewitness or victim to a crime may create from memory a holistic facial composite of the culprit with the assistance of a police operator. The aim is that the composite is recognized by someone who believes that they know the culprit. For this paradigm, participants view a culprit actor on video and following a delay, participant-witnesses construct a holistic system facial composite. Controls do not construct a composite. From a series of arrays of computer-generated, but realistic faces, the holistic system construction method primarily requires participant-witnesses to select the facial images most closely meeting their memory of the culprit. Variation between faces in successive arrays is reduced until ideally the final image possesses a close likeness to the culprit. Participant-witness directed tools can also alter facial features, configurations between features and holistic properties (e.g., age, distinctiveness, skin tone), all within a whole face context. The procedure is designed to closely match the holistic manner by which humans’ process faces. On completion, based on their memory of the culprit, ratings of composite-culprit similarity are collected from the participant-witnesses. Similar ratings are collected from culprit-acquaintance assessors, as a marker of composite recognition likelihood. Following a further delay, all participants — including the controls — attempt to identify the culprit in either a culprit-present or culprit-absent video line-up, to replicate circumstances in which the police have located the correct culprit, or an innocent suspect. Data of control and participant-witness line-up outcomes are presented, demonstrating the positive influence of holistic composite construction on identification accuracy. Correlational analyses are conducted to measure the relationship between assessor and participant-witness composite-culprit similarity ratings, delay, identification accuracy, and confidence to examine which factors influence video line-up outcomes. PMID:26779673

Extended Range Passive Wireless Tag System and Method

NASA Technical Reports Server (NTRS)

Fink, Patrick W. (Inventor); Lin, Gregory Y. (Inventor); Kennedy, Timothy F. (Inventor)

2013-01-01

A passive wireless tag assembly comprises a plurality of antennas and transmission lines interconnected with circuitry and constructed and arranged in a Van Atta array or configuration to reflect an interrogator signal in the direction from where it came. The circuitry may comprise at least one surface acoustic wave (SAW)-based circuit that functions as a signal reflector and is operatively connected with an information circuit. In another embodiment, at least one delay circuit and/or at least one passive modulation circuit(s) are utilized. In yet another embodiment, antennas connected to SAW-based devices are mounted to at least one of the orthogonal surfaces of a corner reflector.

Microwave fiber optics delay line

NASA Astrophysics Data System (ADS)

Slayman, C.; Yen, H. W.

1980-01-01

A microwave delay line is one of the devices used in EW systems for preserving the frequency and phase contents of RF signals. For such applications, delay lines are required to have large dynamic range, wide bandwidth, low insertion loss, and a linear response. The basic components of a fiber-optics delay line are: an optical source, a wideband optical modulator, a spool of single-mode fiber with appropriate length to provide a given microwave signal delay, and a high-speed photodetector with an RF amplifier. This contract program is to study the feasibility of such a fiber-optic delay line in the frequency range of 4.0 to 6.5 GHz. The modulation scheme studied is the direct modulation of injection lasers. The most important issue identified is the frequency response of the injection laser and the photodetector.

Magnonic Crystal as a Delay Line for Low-Noise Auto-Oscillator

DTIC Science & Technology

2015-05-12

Magnonic crystal as a delay line for low-noise auto-oscillator Elena Bankowski and Thomas Meitzler U.S. Army TARDEC, Warren, Michigan 48397, USA...authors propose to use the magnonic crystal patterned on the YIG magnetic film as an efficient delay line in the feedback loop of tunable auto-oscillator...increasing the thickness of such delay line as compare to the YIG film with no pattern. In turn, use of this magnonic crystal opens a way to improve

The across frequency independence of equalization of interaural time delay in the equalization-cancellation model of binaural unmasking.

PubMed

Akeroyd, Michael A

2004-08-01

The equalization stage in the equalization-cancellation model of binaural unmasking compensates for the interaural time delay (ITD) of a masking noise by introducing an opposite, internal delay [N. I. Durlach, in Foundations of Modern Auditory Theory, Vol. II., edited by J. V. Tobias (Academic, New York, 1972)]. Culling and Summerfield [J. Acoust. Soc. Am. 98, 785-797 (1995)] developed a multi-channel version of this model in which equalization was "free" to use the optimal delay in each channel. Two experiments were conducted to test if equalization was indeed free or if it was "restricted" to the same delay in all channels. One experiment measured binaural detection thresholds, using an adaptive procedure, for 1-, 5-, or 17-component tones against a broadband masking noise, in three binaural configurations (N0S180, N180S0, and N90S270). The thresholds for the 1-component stimuli were used to normalize the levels of each of the 5- and 17-component stimuli so that they were equally detectable. If equalization was restricted, then, for the 5- and 17-component stimuli, the N90S270 and N180S0 configurations would yield a greater threshold than the N0S180 configurations. No such difference was found. A subsequent experiment measured binaural detection thresholds, via psychometric functions, for a 2-component complex tone in the same three binaural configurations. Again, no differential effect of configuration was observed. An analytic model of the detection of a complex tone showed that the results were more consistent with free equalization than restricted equalization, although the size of the differences was found to depend on the shape of the psychometric function for detection.

The DARWIN breadboard cryogenic optical delay line

NASA Astrophysics Data System (ADS)

van den Dool, T. C.; Gielesen, W.; Kamphues, F.; Loix, N.; Kooijman, P. P.; de Vries, C.; van Weers, H.; Fleury, K.; Stockman, Y.; Velsink, G.; Benoit, J.; Poupinet, A.; Sève, F.

2017-11-01

TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line (figure 1) for use in future space interferometry missions. The work is performed under ESA contract 17.747/03 in preparation for the DARWIN mission. The breadboard (BB) delay line is representative of a flight mechanism. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a twomirror cat's eye. Magnetic bearings provide frictionless and wear free operation with zero-hysteresis. The design of the BB delay line has been completed. The development test program, including operation at 100 K has been completed. The verification test programme is currently being carried out and will include functional testing at 40 K.

Intensity coding in electric hearing: effects of electrode configurations and stimulation waveforms.

PubMed

Chua, Tiffany Elise H; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were five Clarion cochlear implant users. For each subject, data from apical, middle, and basal electrode positions were collected when possible. Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen.

Generation of tunable infrared radiation by stimulated Raman scattering on hydrogen in a prism-lens optical delay line

NASA Astrophysics Data System (ADS)

Andreev, R. B.; Butylkin, V. S.; Evtiushkin, V. A.; Fisher, P. S.; Khabarov, V. V.

1983-03-01

The threshold of stimulated Raman scattering was lowered by filling an optical delay line with hydrogen. Pumping was by a tunable neodymium laser. Lens-prism combinations were used as phase correctors in the delay line. The dependences of the energy of the Stokes component on the pump energy determined experimentally for different numbers of transits through the delay line were compared with the results of a calculation allowing for the losses in the components of this line. When the frequency conversion was by a factor of at least 2 and the tuning range was wide (tens of percent), the optimal performance was obtained from the optical delay line when total-internal-reflection prisms and lenses were combined in a single component and oriented at the Brewster angle.

BRIEF COMMUNICATIONS: Generation of tunable infrared radiation by stimulated Raman scattering on hydrogen in a prism-lens optical delay line

NASA Astrophysics Data System (ADS)

Andreev, R. B.; Butylkin, V. S.; Evtyushkin, V. A.; Fisher, P. S.; Khabarov, V. V.

1983-03-01

The threshold of stimulated Raman scattering was lowered by filling an optical delay line with hydrogen. Pumping was by a tunable neodymium laser. Lens-prism combinations were used as phase correctors in the delay line. The dependences of the energy of the Stokes component on the pump energy determined experimentally for different numbers of transits through the delay line were compared with the results of a calculation allowing for the losses in the components of this line. When the frequency conversion was by a factor of at least 2 and the tuning range was wide (tens of percent), the optimal performance was obtained from the optical delay line when total-internal-reflection prisms and lenses were combined in a single component and oriented at the Brewster angle.

UCTM2: An updated User friendly Configurable Trigger, scaler and delay Module for nuclear and particle physics

NASA Astrophysics Data System (ADS)

Bourrion, O.; Boyer, B.; Derome, L.; Pignol, G.

2016-06-01

We developed a highly integrated and versatile electronic module to equip small nuclear physics experiments and lab teaching classes: the User friendly Configurable Trigger, scaler and delay Module for nuclear and particle physics (UCTM). It is configurable through a Graphical User Interface (GUI) and provides a large number of possible trigger conditions without any Hardware Description Language (HDL) required knowledge. This new version significantly enhances the previous capabilities by providing two additional features: signal digitization and time measurements. The design, performances and a typical application are presented.

Application configuration selection for energy-efficient execution on multicore systems

DOE PAGES

Wang, Shinan; Luo, Bing; Shi, Weisong; ...

2015-09-21

Balanced performance and energy consumption are incorporated in the design of modern computer systems. Several runtime factors, such as concurrency levels, thread mapping strategies, and dynamic voltage and frequency scaling (DVFS) should be considered in order to achieve optimal energy efficiency fora workload. Selecting appropriate run-time factors, however, is one of the most challenging tasks because the run-time factors are architecture-specific and workload-specific. And while most existing works concentrate on either static analysis of the workload or run-time prediction results, we present a hybrid two-step method that utilizes concurrency levels and DVFS settings to achieve the energy efficiency configuration formore » a worldoad. The experimental results based on a Xeon E5620 server with NPB and PARSEC benchmark suites show that the model is able to predict the energy efficient configuration accurately. On average, an additional 10% EDP (Energy Delay Product) saving is obtained by using run-time DVFS for the entire system. An off-line optimal solution is used to compare with the proposed scheme. Finally, the experimental results show that the average extra EDP saved by the optimal solution is within 5% on selective parallel benchmarks.« less

Acute ethanol does not always affect delay discounting in rats selected to prefer or avoid ethanol.

PubMed

Wilhelm, Clare J; Mitchell, Suzanne H

2012-01-01

The purpose of this study was to determine whether animals predisposed to prefer alcohol possess an altered acute response to alcohol on a delay discounting task relative to animals predisposed to avoid alcohol. We used rats selected to prefer or avoid alcohol to assess whether genotype moderates changes in delay discounting induced by acute ethanol exposure. Selectively bred rat lines of Sardinian alcohol-preferring (sP; n = 8) and non-preferring (sNP; n = 8) rats, and alko alcohol (AA, n = 8) and alko non-alcohol (ANA, n = 8) rats were trained in an adjusting amount task to assess delay discounting. There were no significant effects of line on baseline discounting; however, both lines of alcohol-preferring rats exhibit slowed reaction times. Acute ethanol (0, 0.25, 0.5 g/kg) treatment also had no effect on delay discounting in any of the selectively bred rat lines. Our data indicate that in these lines of animals, alcohol preference or avoidance has no impact on delay discounting following acute ethanol exposure. It is possible that other genetic models or lines may be differentially affected by alcohol and exhibit qualitatively and quantitatively different responses in delay discounting tasks.

The guidance of visual search by shape features and shape configurations.

PubMed

McCants, Cody W; Berggren, Nick; Eimer, Martin

2018-03-01

Representations of target features (attentional templates) guide attentional object selection during visual search. In many search tasks, targets objects are defined not by a single feature but by the spatial configuration of their component shapes. We used electrophysiological markers of attentional selection processes to determine whether the guidance of shape configuration search is entirely part-based or sensitive to the spatial relationship between shape features. Participants searched for targets defined by the spatial arrangement of two shape components (e.g., hourglass above circle). N2pc components were triggered not only by targets but also by partially matching distractors with one target shape (e.g., hourglass above hexagon) and by distractors that contained both target shapes in the reverse arrangement (e.g., circle above hourglass), in line with part-based attentional control. Target N2pc components were delayed when a reverse distractor was present on the opposite side of the same display, suggesting that early shape-specific attentional guidance processes could not distinguish between targets and reverse distractors. The control of attention then became sensitive to spatial configuration, which resulted in a stronger attentional bias for target objects relative to reverse and partially matching distractors. Results demonstrate that search for target objects defined by the spatial arrangement of their component shapes is initially controlled in a feature-based fashion but can later be guided by templates for spatial configurations. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Distortion management in slow-light pulse delay.

PubMed

Stenner, Michael D; Neifeld, Mark A; Zhu, Zhaoming; Dawes, Andrew M C; Gauthier, Daniel J

2005-12-12

We describe a methodology to maximize slow-light pulse delay subject to a constraint on the allowable pulse distortion. We show that optimizing over a larger number of physical variables can increase the distortion-constrained delay. We demonstrate these concepts by comparing the optimum slow-light pulse delay achievable using a single Lorentzian gain line with that achievable using a pair of closely-spaced gain lines. We predict that distortion management using a gain doublet can provide approximately a factor of 2 increase in slow-light pulse delay as compared with the optimum single-line delay. Experimental results employing Brillouin gain in optical fiber confirm our theoretical predictions.

Prototype high speed optical delay line for stellar interferometry

NASA Astrophysics Data System (ADS)

Colavita, M. M.; Hines, B. E.; Shao, M.; Klose, G. J.; Gibson, B. V.

1991-12-01

The long baselines of the next-generation ground-based optical stellar interferometers require optical delay lines which can maintain nm-level path-length accuracy while moving at high speeds. NASA-JPL is currently designing delay lines to meet these requirements. The design is an enhanced version of the Mark III delay line, with the following key features: hardened, large diameter wheels, rather than recirculating ball bearings, to reduce mechanical noise; a friction-drive cart which bears the cable-dragging forces, and drives the optics cart through a force connection only; a balanced PZT assembly to enable high-bandwidth path-length control; and a precision aligned flexural suspension for the optics assembly to minimize bearing noise feedthrough. The delay line is fully programmable in position and velocity, and the system is controlled with four cascaded software feedback loops. Preliminary performance is a jitter in any 5 ms window of less than 10 nm rms for delay rates of up to 28 mm/s; total jitter is less than 10 nm rms for delay rates up to 20 mm/s.

Determination of chlorine, sulfur and carbon in reinforced concrete structures by double-pulse laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Labutin, Timur A.; Popov, Andrey M.; Zaytsev, Sergey M.; Zorov, Nikita B.; Belkov, Mikhail V.; Kiris, Vasilii V.; Raikov, Sergey N.

2014-09-01

Accurate and reliable quantitative determination of non-metal corrosion agents in concrete is still an actual task of analytical use of LIBS. Two double-pulse LIBS systems were tested as a tool for the determination of chlorine, sulfur and carbon in concretes. Both systems had collinear configuration; a laboratory setup was equipped with an ICCD and two lasers (355/532 nm + 540 nm), but a CCD was a detector for a mobile system with one laser (1064 nm). Analytical lines of Cl I at 837.59 nm, S I at 921 nm and C I at 247.86 nm were used to plot calibration curves. Optimal interpulse delays for the laboratory setup were 4 μs for chlorine and 2.8 μs for carbon, while an interpulse delay of 2 μs was optimal for chlorine and sulfur determination with the mobile system. We suggested the normalization of the Cl I line at 837.59 nm to the Mg II line at 279.08 nm (visible at 837.23 nm in the third order) to compensate for pulse-to-pulse fluctuations of chlorine lines. It provided the decrease of the detection limit of chlorine from 400 ppm to 50 ppm. Therefore, we reported that LIBS can be used to determine main corrosive active substances under ambient conditions in concrete below critical threshold values. Moreover, the application of the mobile system for in-situ qualitative assessment of corrosion way of a steel cage of a swimming pool dome was also demonstrated. It was found that chloride corrosion due to the disinfection of water was the main way for corrosion of the open part steel and the steel rebar inside the concrete.

Advanced optical delay line demonstrator

NASA Astrophysics Data System (ADS)

van den Dool, Teun; Kamphues, Fred; Fouss, B.; Henrioulle, K.; Hogenhuis, Harm

2004-09-01

TNO TPD, in cooperation with Micromega-Dynamics and Dutch Space, has designed an advanced Optical Delay Line (ODL) for use in future ground based and space interferometry missions. The work is performed under NIVR contract in preparation for GENIE and DARWIN. Using the ESO PRIMA DDL requirements as a baseline, the delay line can be used for PRIMA and GENIE without any modifications. The delay line design is modular and flexible, which makes scaling for other applications a relatively easy task. The ODL has a single linear motor actuator for Optical Path Difference (OPD) control, driving a two-mirror cat"s eye with SiC mirrors and CFRP structure. Magnetic bearings provide frictionless and wear free operation with zerohysteresis. The delay line is currently being assembled and will be subjected to a comprehensive test program in the second half of 2004.

Intensity coding in electric hearing: Effects of electrode configurations and stimulation waveforms

PubMed Central

Chua, Tiffany Elise H.; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Objectives Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception, but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. Design The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were 5 Clarion cochlear implant users. For each subject, data from apical, middle and basal electrode positions were collected when possible. Results Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. Conclusions The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings, nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen. PMID:21610498

Optical sampling by laser cavity tuning.

PubMed

Hochrein, Thomas; Wilk, Rafal; Mei, Michael; Holzwarth, Ronald; Krumbholz, Norman; Koch, Martin

2010-01-18

Most time-resolved optical experiments rely either on external mechanical delay lines or on two synchronized femtosecond lasers to achieve a defined temporal delay between two optical pulses. Here, we present a new method which does not require any external delay lines and uses only a single femtosecond laser. It is based on the cross-correlation of an optical pulse with a subsequent pulse from the same laser. Temporal delay between these two pulses is achieved by varying the repetition rate of the laser. We validate the new scheme by a comparison with a cross-correlation measurement carried out with a conventional mechanical delay line.

Development of a Low-cost, FPGA-based, Delay Line Particle Detector for Satellite and Sounding Rocket Applications

NASA Astrophysics Data System (ADS)

Harrington, M.; Kujawski, J. T.; Adrian, M. L.; Weatherwax, A. T.

2013-12-01

Electrons are, by definition, a fundamental, chemical and electromagnetic constituent of any plasma. This is especially true within the partially ionized plasmas of Earth's ionosphere where electrons are a critical component of a vast array of plasma processes. Siena College is working on a novel method of processing information from electron spectrometer anodes using delay line techniques and inexpensive COTS electronics to track the movement of high-energy particles. Electron spectrometers use a variety of techniques to determine where an amplified electron cloud falls onto a collecting surface. One traditional method divides the collecting surface into sectors and uses a single detector for each sector. However, as the angular and spatial resolution increases, so does the number of detectors, increasing power consumption, cost, size, and weight of the system. An alternative approach is to connect each sector with a delay line built within the PCB material which is shielded from cross talk by a flooded ground plane. Only one pair of detectors (e.g., one at each end of the chain) are needed with the delay line technique which is different from traditional delay line detectors which use either Application Specific Integrated Circuits (ASICs) or very fast clocks. In this paper, we report on the implementation and testing of a delay line detector using a low-cost Xilinx FPGA and a thirty-two sector delay system. This Delay Line Detector has potential satellite and rocket flight applications due to its low cost, small size and power efficiency

Lossless microwave photonic delay line using a ring resonator with an integrated semiconductor optical amplifier

NASA Astrophysics Data System (ADS)

Xie, Yiwei; Zhuang, Leimeng; Boller, Klaus-Jochen; Lowery, Arthur James

2017-06-01

Optical delay lines implemented in photonic integrated circuits (PICs) are essential for creating robust and low-cost optical signal processors on miniaturized chips. In particular, tunable delay lines enable a key feature of programmability for the on-chip processing functions. However, the previously investigated tunable delay lines are plagued by a severe drawback of delay-dependent loss due to the propagation loss in the constituent waveguides. In principle, a serial-connected amplifier can be used to compensate such losses or perform additional amplitude manipulation. However, this solution is generally unpractical as it introduces additional burden on chip area and power consumption, particularly for large-scale integrated PICs. Here, we report an integrated tunable delay line that overcomes the delay-dependent loss, and simultaneously allows for independent manipulation of group delay and amplitude responses. It uses a ring resonator with a tunable coupler and a semiconductor optical amplifier in the feedback path. A proof-of-concept device with a free spectral range of 11.5 GHz and a delay bandwidth in the order of 200 MHz is discussed in the context of microwave photonics and is experimentally demonstrated to be able to provide a lossless delay up to 1.1 to a 5 ns Gaussian pulse. The proposed device can be designed for different frequency scales with potential for applications across many other areas such as telecommunications, LIDAR, and spectroscopy, serving as a novel building block for creating chip-scale programmable optical signal processors.

High-repetition-rate optical delay line using a micromirror array and galvanometer mirror for a terahertz system.

PubMed

Kitahara, Hideaki; Tani, Masahiko; Hangyo, Masanori

2009-07-01

We developed a high-repetition-rate optical delay line based on a micromirror array and galvanometer mirror for terahertz time-domain spectroscopy. The micromirror array is fabricated by using the x-ray lithographic technology. The measurement of terahertz time-domain waveforms with the new optical delay line is demonstrated successfully up to 25 Hz.

One vs two primary LOX feedline configuration study for the National Launch System

NASA Technical Reports Server (NTRS)

Dill, K.; Davis, D.; Bates, R.; Tarwater, R.

1992-01-01

Six single LOX feedline designs were evaluated for use on the National Launch Vehicle. A single feedline design, designated the 'Spider', was chosen and compared to the baseline system. The baseline configuration employs two 20-inch I.D. lines, each supplying LOX to three 650,000 lbf thrust Space Transportation Main Engines. Five single feedline diameters were examined for the spider configuration; 22, 24, 26, 28, and 30-inch I.D. System dry weights and LOX residuals were estimated. These parameters, along with calculated staged mass for the different single line and baseline configurations, were used to calculate the payload mass to orbit. For the cases where LOX is drained to minimum NPSP conditions, none of the single lines performed as well as the dual line system, although the 22-inch diameter single line compared well. However, for the cases where LOX is drained to operating levels (LOX level at the booster and spider manifolds for the dual and single line configurations, respectively), the 22 - 26-inch I.D. single line systems show a greater payload capability.

How to induce multiple delays in coupled chaotic oscillators?

NASA Astrophysics Data System (ADS)

Bhowmick, Sourav K.; Ghosh, Dibakar; Roy, Prodyot K.; Kurths, Jürgen; Dana, Syamal K.

2013-12-01

Lag synchronization is a basic phenomenon in mismatched coupled systems, delay coupled systems, and time-delayed systems. It is characterized by a lag configuration that identifies a unique time shift between all pairs of similar state variables of the coupled systems. In this report, an attempt is made how to induce multiple lag configurations in coupled systems when different pairs of state variables attain different time shift. A design of coupling is presented to realize this multiple lag synchronization. Numerical illustration is given using examples of the Rössler system and the slow-fast Hindmarsh-Rose neuron model. The multiple lag scenario is physically realized in an electronic circuit of two Sprott systems.

TECHNICAL DESIGN NOTE: Picosecond resolution programmable delay line

NASA Astrophysics Data System (ADS)

Suchenek, Mariusz

2009-11-01

The note presents implementation of a programmable delay line for digital signals. The tested circuit has a subnanosecond delay range programmable with a resolution of picoseconds. Implementation of the circuit was based on low-cost components, easily available on the market.

Motion/visual cueing requirements for vortex encounters during simulated transport visual approach and landing

NASA Technical Reports Server (NTRS)

Parrish, R. V.; Bowles, R. L.

1983-01-01

This paper addresses the issues of motion/visual cueing fidelity requirements for vortex encounters during simulated transport visual approaches and landings. Four simulator configurations were utilized to provide objective performance measures during simulated vortex penetrations, and subjective comments from pilots were collected. The configurations used were as follows: fixed base with visual degradation (delay), fixed base with no visual degradation, moving base with visual degradation (delay), and moving base with no visual degradation. The statistical comparisons of the objective measures and the subjective pilot opinions indicated that although both minimum visual delay and motion cueing are recommended for the vortex penetration task, the visual-scene delay characteristics were not as significant a fidelity factor as was the presence of motion cues. However, this indication was applicable to a restricted task, and to transport aircraft. Although they were statistically significant, the effects of visual delay and motion cueing on the touchdown-related measures were considered to be of no practical consequence.

One-dimensional photonic crystals for code-division multiple access

NASA Astrophysics Data System (ADS)

Wang, Shamino Yuanliang

One-dimensional photonic crystals exhibit reduced group velocity and huge dispersion at their rejection band edge frequencies. Therefore they are natural candidates as optical delay lines, dispersion compensators, and pulse reshapers. Using wavelength tunable pulses spectrally sliced from a mode-locked fiber laser, the transmission mode measurement was performed in the time domain with single picosecond resolution. Group delays and dispersion were measured with an autocorrelator as an ultrafast optical detector and cross-correlator. Our experimental results agree qualitatively with the theoretical and simulation predictions. A maximum group delay of 10 ps for a commercial 3 mm long uniform fiber Bragg grating and that of 22.6 ps for a research laboratory fabricated 1 cm grating were measured, corresponding to a group velocity 66% of the speed of light in bare fiber. We have also demonstrated in the overlap transmission region of a grating pair both gratings contribute to the group delay while the group velocity dispersion was canceled, resulting in additive delay in transmission with minimal pulse reshaping. This compound grating configuration was further expanded as specially designed grating sequence encoders and decoders in matched filter CDMA. The transmitter grating sequence temporally stretched the input pulse into a long time scale low peak intensity pseudorandom noise, while the conjugate grating sequence in the receiver performed pulse reconstruction and data recovery. A temporal FWHM contrast ratio of 2.5 and a peak intensity contrast ratio of 10 between the correctly and incorrectly decoded signals were achieved. Armed with more sophisticated grating designs we believe this would be a powerful solution to CDMA orthogonal code requirements.

Current status of the IOTA interferometer

NASA Astrophysics Data System (ADS)

Carleton, Nathaniel P.; Traub, Wesley A.; Lacasse, Marc G.; Nisenson, Peter; Pearlman, Michael R.; Reasenberg, Robert D.; Xu, Xinqi; Coldwell, Charles M.; Panasyuk, Alexander; Benson, James A.; Papaliolios, Costas; Predmore, Read; Schloerb, F. P.; Dyck, H. M.; Gibson, David M.

1994-06-01

The first two telescopes of the Infrared-Optical Telescope Array (IOTA) project are now in place and yielding data at the Smithsonian Institution's F. L. Whipple Observatory on Mt. Hopkins, near Tucson, Arizona. The IOTA collectors are 45 cm in diameter, and may be moved to various stations in an L-shaped configuration with a maximum baseline of 38 m. A third collector will be added as soon as funding permits. Each light-collector assembly consists of a siderostat feeding a stationary afocal Cassegrain telescope that produces a 10-X reduced parallel beam, which is in turn directed vertically downward by a piezo-driven active mirror that stabilizes the ultimate image position. The reduced beams enter an evacuated envelope and proceed to the corner of the array, where they are turned back along one arm for path compensation. The delay line, in one beam, consists of two parts: one dihedral reflector positioned in a slew-and-clamp mode to give the major part of the desired delay; and a second dihedral mounted on an air-bearing carriage to provide the variable delay that is needed. After delay, the beams exit from the vacuum and are directed by dichroic mirrors into the infrared beam-combination and detection system. The visible light passes on to another area, to the image-tracker detectors and the visible-light combination and detection system. The beams are combined in pupil-plane mode on beam splitters. The combined IR beams are conveyed to two cooled single-element InSb detectors. The combined visible-light beams are focussed by lenslet arrays onto multimode optical fibers that lead to the slit of a specially-designed prism spectrometer. For the visible mode, the delay line is run at several wavelengths on one side of the zero- path point, so that several cycles of interference occur across the spectrum. First results were obtained with the IR system, giving visibilities for several K and M stars, using 2.2 micrometers radiation on a N-S baseline of 21.2 m. From these measurements we obtained preliminary estimates of effective stellar diameters in the K band.

Ogura-CMS in Chinese cabbage (Brassica rapa ssp. pekinensis) causes delayed expression of many nuclear genes.

PubMed

Dong, Xiangshu; Kim, Wan Kyu; Lim, Yong-Pyo; Kim, Yeon-Ki; Hur, Yoonkang

2013-02-01

We investigated the mechanism regulating cytoplasmic male sterility (CMS) in Brassica rapa ssp. pekinensis using floral bud transcriptome analyses of Ogura-CMS Chinese cabbage and its maintainer line in B. rapa 300-K oligomeric probe (Br300K) microarrays. Ogura-CMS Chinese cabbage produced few and infertile pollen grains on indehiscent anthers. Compared to the maintainer line, CMS plants had shorter filaments and plant growth, and delayed flowering and pollen development. In microarray analysis, 4646 genes showed different expression, depending on floral bud size, between Ogura-CMS and its maintainer line. We found 108 and 62 genes specifically expressed in Ogura-CMS and its maintainer line, respectively. Ogura-CMS line-specific genes included stress-related, redox-related, and B. rapa novel genes. In the maintainer line, genes related to pollen coat and germination were specifically expressed in floral buds longer than 3mm, suggesting insufficient expression of these genes in Ogura-CMS is directly related to dysfunctional pollen. In addition, many nuclear genes associated with auxin response, ATP synthesis, pollen development and stress response had delayed expression in Ogura-CMS plants compared to the maintainer line, which is consistent with the delay in growth and development of Ogura-CMS plants. Delayed expression may reduce pollen grain production and/or cause sterility, implying that mitochondrial, retrograde signaling delays nuclear gene expression. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

The design of a breadboard cryogenic optical delay line for DARWIN

NASA Astrophysics Data System (ADS)

van den Dool, Teun C.; Kamphues, Fred; Fouss, B.; Henrioulle, K.; Kooijman, P. P.; Visser, Martijn; Velsink, G.; Fleury, K.

2004-09-01

TNO TPD, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard (BB) delay line is representative of a flight mechanism, with all materials and processes used being flight representative. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat's eye. Magnetic bearings provide frictionless and wear free operation with zero-hysteresis. Overall power consumption is below the ESA specification of 2.5 W. The power dissipated on the optical bench at 40 K is considerably less than the maximum allowable 25 mW. The design of the BB delay line has been completed. Verification testing, including functional testing at 40 K, is planned to start in the 4th quarter of 2004. The current design could also be adapted to the needs of the TPF-I mission.

The design of a breadboard cryogenic optical delay line for DARWIN

NASA Astrophysics Data System (ADS)

van den Dool, Teun; Kamphues, Fred; Fouss, B.; Henrioulle, K.; Kooijman, P. P.; Visser, Martijn; Velsink, G.; Fleury, K.

2004-09-01

TNO TPD, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard (BB) delay line is representative of a future flight mechanism, with all materials and processes used being flight representative. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat"s eye. Magnetic bearings provide frictionless and wear free operation with zero-hysteresis. Overall power consumption is below the ESA specification of 2.5 W. The power dissipated on the optical bench at 40 K is considerably less than the maximum allowable 25 mW. The BB delay line will be built in the second half of 2004. The manufacturing and assembly phase is followed by a comprehensive test program, including functional testing at 40 K in 2005. The tests will be carried out by Alcatel Space and SAGEIS-CSO.

Unsteady Performance of Finite-Span Pitching Propulsors in Mixtures of Side-by-Side and In-Line Arrangements

NASA Astrophysics Data System (ADS)

Kurt, Melike; Moored, Keith

2016-11-01

Birds, insects, and fish propel themselves by flapping their wings or oscillating their fins in unsteady motions. Many of these animals fly or swim in groups or collectives, typically described as flocks, swarms and schools. The three-dimensional steady flow interactions and the two dimensional unsteady flow interactions that occur in collectives are well characterized. However, the interactions that occur among three-dimensional unsteady propulsors remain relatively unexplored. The aim of the current study is to measure the forces acting on and the energetics of two finite-span pitching wings. The wings are arranged in mixtures of canonical in-line and side-by-side configurations while the phase delay between the pitching wings is varied. The thrust force, fluid-mediated interaction force between the wings and the propulsive efficiency are quantified. The three-dimensional interaction mechanisms are compared and contrasted with previously examined two-dimensional mechanisms. Stereoscopic particle image velocimetry is employed to characterize the three-dimensional flow structures along the span of the pitching wings.

Blood platelet adhesion to protein studied by on-line acoustic wave sensor.

PubMed

Cavic, B A; Freedman, J; Morel, Z; Mody, M; Rand, M L; Stone, D C; Thompson, M

2001-03-01

The attachment of blood platelets to the surface of bare and protein-coated thickness-shear mode acoustic wave devices operating in a flow-through configuration has been studied. Platelets in washed from bind to the gold electrodes of such sensors, but the resulting frequency shifts are far less than predicted by the conventional mass-based model of device operation. Adherence to albumin and various types of collagen can be produced by on-line introduction of protein or by a pre-coating strategy. Differences in attachment of platelets to collagen types I and IV and the Horm variety can be detected. Platelets attached to collagen yield an interesting delayed, but reversible signal on exposure to a flowing medium of low pH. Scanning electron microscopy of sensor surfaces at various time points in this experiment reveals that originally intact platelets are eventually destroyed by the high acidity of the medium. The reversible frequency is attributed to the presence of removable platelet granular components at the sensor-liquid interface.

High rate science data handling on Space Station Freedom

NASA Technical Reports Server (NTRS)

Handley, Thomas H., Jr.; Masline, Richard C.

1990-01-01

A study by NASA's User Information System Working Group for Space Station Freedom (SSF) has determined that the proposed onboard Data Management System, as initially configured, will be incapable of handling the data-generation rates typical of numerous scientific sensor payloads; many of these generate data at rates in excess of 10 Mbps, and there are at least four cases of rates in excess of 300 Mbps. The SSF Working Group has accordingly suggested an alternative conceptual architecture based on technology expected to achieve space-qualified status by 1995. The architecture encompasses recorders with rapid data-ingest capabilities and massive storage capabilities, optical delay lines allowing the recording of only the phenomena of interest, and data flow-compressing image processors.

Physics Goals for the Planned Next Linear Collider Engineering Test Facility

NASA Astrophysics Data System (ADS)

Raubenheimer, T. O.

2001-10-01

The Next Linear Collider (NLC) Collaboration is planning to construct an Engineering Test Facility (ETF) at Fermilab. As presently envisioned, the ETF would comprise a fundamental unit of the NLC main linac to include X-band klystrons and modulators, a delay-line power-distribution system (DLDS), and NLC accelerating structures that serve as loads. The principal purpose of the ETF is to validate stable operation of the power-distribution system, first without beam, then with a beam having the NLC pulse structure. This paper concerns the possibility of configuring and using the ETF to accelerate beam with an NLC pulse structure, as well as of doing experiments to measure beam-induced wakefields in the rf structures and their influence back on the beam.

Improved memory word line configuration allows high storage density

NASA Technical Reports Server (NTRS)

1966-01-01

Plated wire memory word drive line allows high storage density, good plated wire transmission and a simplified memory plane configuration. A half-turn word drive line with a magnetic keeper is used. The ground plane provides the return path for both the word current and the plated wire transmission line.

Skeletal muscle characterization of Japanese quail line selectively bred for lower body weight as an avian model of delayed muscle growth with hypoplasia.

PubMed

Choi, Young Min; Suh, Yeunsu; Shin, Sangsu; Lee, Kichoon

2014-01-01

This study was designed to extensively characterize the skeletal muscle development in the low weight (LW) quail selected from random bred control (RBC) Japanese quail in order to provide a new avian model of impaired and delayed growth in physically normal animals. The LW line had smaller embryo and body weights than the RBC line in all age groups (P<0.05). During 3 to 42 d post-hatch, the LW line exhibited approximately 60% smaller weight of pectoralis major muscle (PM), mainly resulting from lower fiber numbers compared to the RBC line (P<0.05). During early post-hatch period when myotubes are still actively forming, the LW line showed impaired PM growth with prolonged expression of Pax7 and lower expression levels of MyoD, Myf-5, and myogenin (P<0.05), likely leading to impairment of myogenic differentiation and consequently, reduced muscle fiber formation. Additionally, the LW line had delayed transition of neonatal to adult myosin heavy chain isoform, suggesting delayed muscle maturation. This is further supported by the finding that the LW line continued to grow unlike the RBC line; difference in the percentages of PMW to body weights between both quail lines diminished with increasing age from 42 to 75 d post-hatch. This delayed muscle growth in the LW line is accompanied by higher levels of myogenin expression at 42 d (P<0.05), higher percentage of centered nuclei at 42 d (P<0.01), and greater rate of increase in fiber size between 42 and 75 d post-hatch (P<0.001) compared to the RBC line. Analysis of physiological, morphological, and developmental parameters during muscle development of the LW quail line provided a well-characterized avian model for future identification of the responsible genes and for studying mechanisms of hypoplasia and delayed muscle growth.

Wide-area Power System Damping Control Coordination Based on Particle Swarm Optimization with Time Delay Considered

NASA Astrophysics Data System (ADS)

Zhang, J. Y.; Jiang, Y.

2017-10-01

To ensure satisfactory dynamic performance of controllers in time-delayed power systems, a WAMS-based control strategy is investigated in the presence of output feedback delay. An integrated approach based on Pade approximation and particle swarm optimization (PSO) is employed for parameter configuration of PSS. The coordination configuration scheme of power system controllers is achieved by a series of stability constraints at the aim of maximizing the minimum damping ratio of inter-area mode of power system. The validity of this derived PSS is verified on a prototype power system. The findings demonstrate that the proposed approach for control design could damp the inter-area oscillation and enhance the small-signal stability.

Medial temporal lobe contributions to short-term memory for faces

PubMed Central

Race, Elizabeth; LaRocque, Karen F.; Keane, Margaret M.; Verfaellie, Mieke

2015-01-01

The role of the medial temporal lobes (MTL) in short-term memory (STM) remains a matter of debate. While imaging studies commonly show hippocampal activation during short-delay memory tasks, evidence from amnesic patients with MTL lesions is mixed. It has been argued that apparent STM impairments in amnesia may reflect long-term memory (LTM) contributions to performance. We challenge this conclusion by demonstrating that MTL amnesic patients show impaired delayed matching-to-sample (DMS) for faces in a task that meets both a traditional delay-based and a recently proposed distractor-based criterion for classification as a STM task. In Experiment 1, we demonstrate that our face DMS task meets the proposed distractor-based criterion for STM classification, in that extensive processing of delay-period distractor stimuli disrupts performance of healthy individuals. In Experiment 2, MTL amnesic patients with lesions extending into anterior subhippocampal cortex, but not patients with lesions limited to the hippocampus, show impaired performance on this task without distraction at delays as short as 8s, within temporal range of delay-based STM classification, in the context of intact perceptual matching performance. Experiment 3 provides support for the hypothesis that STM for faces relies on configural processing by showing that the extent to which healthy participants’ performance is disrupted by interference depends on the configural demands of the distractor task. Together, these findings are consistent with the notion that the amnesic impairment in STM for faces reflects a deficit in configural processing associated with subhippocampal cortices and provide novel evidence that the MTL supports cognition beyond the LTM domain. PMID:23937185

Wide Band Low Noise Love Wave Magnetic Field Sensor System.

PubMed

Kittmann, Anne; Durdaut, Phillip; Zabel, Sebastian; Reermann, Jens; Schmalz, Julius; Spetzler, Benjamin; Meyners, Dirk; Sun, Nian X; McCord, Jeffrey; Gerken, Martina; Schmidt, Gerhard; Höft, Michael; Knöchel, Reinhard; Faupel, Franz; Quandt, Eckhard

2018-01-10

We present a comprehensive study of a magnetic sensor system that benefits from a new technique to substantially increase the magnetoelastic coupling of surface acoustic waves (SAW). The device uses shear horizontal acoustic surface waves that are guided by a fused silica layer with an amorphous magnetostrictive FeCoSiB thin film on top. The velocity of these so-called Love waves follows the magnetoelastically-induced changes of the shear modulus according to the magnetic field present. The SAW sensor is operated in a delay line configuration at approximately 150 MHz and translates the magnetic field to a time delay and a related phase shift. The fundamentals of this sensor concept are motivated by magnetic and mechanical simulations. They are experimentally verified using customized low-noise readout electronics. With an extremely low magnetic noise level of ≈100 pT/[Formula: see text], a bandwidth of 50 kHz and a dynamic range of 120 dB, this magnetic field sensor system shows outstanding characteristics. A range of additional measures to further increase the sensitivity are investigated with simulations.

Surface acoustic wave unidirectional transducers for quantum applications

NASA Astrophysics Data System (ADS)

Ekström, Maria K.; Aref, Thomas; Runeson, Johan; Björck, Johan; Boström, Isac; Delsing, Per

2017-02-01

The conversion efficiency of electric microwave signals into surface acoustic waves in different types of superconducting transducers is studied with the aim of quantum applications. We compare delay lines containing either conventional symmetric transducers (IDTs) or unidirectional transducers (UDTs) at 2.3 GHz and 10 mK. The UDT delay lines improve the insertion loss with 4.7 dB and a directivity of 22 dB is found for each UDT, indicating that 99.4% of the acoustic power goes in the desired direction. The power lost in the undesired direction accounts for more than 90% of the total loss in IDT delay lines, but only ˜3% of the total loss in the floating electrode unidirectional transducer delay lines.

Repetition rate multiplication of frequency comb using all-pass fiber resonator

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

Yang, Lijun; Yang, Honglei; Zhang, Hongyuan

2016-09-15

We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The inputmore » and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.« less

Stabilization of self-mode-locked quantum dash lasers by symmetric dual-loop optical feedback

NASA Astrophysics Data System (ADS)

Asghar, Haroon; Wei, Wei; Kumar, Pramod; Sooudi, Ehsan; McInerney, John. G.

2018-02-01

We report experimental studies of the influence of symmetric dual-loop optical feedback on the RF linewidth and timing jitter of self-mode-locked two-section quantum dash lasers emitting at 1550 nm. Various feedback schemes were investigated and optimum levels determined for narrowest RF linewidth and low timing jitter, for single-loop and symmetric dual-loop feedback. Two symmetric dual-loop configurations, with balanced and unbalanced feedback ratios, were studied. We demonstrate that unbalanced symmetric dual loop feedback, with the inner cavity resonant and fine delay tuning of the outer loop, gives narrowest RF linewidth and reduced timing jitter over a wide range of delay, unlike single and balanced symmetric dual-loop configurations. This configuration with feedback lengths 80 and 140 m narrows the RF linewidth by 4-67x and 10-100x, respectively, across the widest delay range, compared to free-running. For symmetric dual-loop feedback, the influence of different power split ratios through the feedback loops was determined. Our results show that symmetric dual-loop feedback is markedly more effective than single-loop feedback in reducing RF linewidth and timing jitter, and is much less sensitive to delay phase, making this technique ideal for applications where robustness and alignment tolerance are essential.

Mixed Modeling of a SAW Delay Line Using VHDL-AMS

NASA Technical Reports Server (NTRS)

Wilson, William C.; Atkinson, Gary M.

2006-01-01

To aid in the development of SAW sensors for aerospace applications we have created a model of a SAW Delay line using VHDL. The model implements the Impulse Response method to calculate the frequency response, impedance, and insertion loss. The model includes optimization for the number of finger pairs in the IDTs and for the aperture height. This paper presents the model and the results from the model for a SAW delay line design.

First-principles studies of Te line-ordered alloys in a MoS2 monolayer

NASA Astrophysics Data System (ADS)

Andriambelaza, N. F.; Mapasha, R. E.; Chetty, N.

2018-04-01

The thermodynamic stability, structural and electronic properties of Te line-ordered alloys are investigated using density functional theory (DFT) methods. Thirty four possible Te line-ordered alloy configurations are found in a 5×5 supercell of a MoS2 monolayer. The calculated formation energies show that the Te line-ordered alloy configurations are thermodynamically stable at 0 K and agree very well with the random alloys. The lowest energy configurations at each concentration correspond to the configuration where the Te atom rows are far apart from each other (avoiding clustering) within the supercell. The variation of the lattice constant at different concentrations obey Vegard's law. The Te line-ordered alloys fine tune the band gap of a MoS2 monolayer although deviating from linearity behavior. Our results suggest that the Te line-ordered alloys can be an effective way to modulate the band gap of a MoS2 monolayer for nanoelectronic, optoelectronic and nanophotonic applications.

Improved On-Chip Measurement of Delay in an FPGA or ASIC

NASA Technical Reports Server (NTRS)

Chen, Yuan; Burke, Gary; Sheldon, Douglas

2007-01-01

An improved design has been devised for on-chip-circuitry for measuring the delay through a chain of combinational logic elements in a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). In the improved design, the delay chain does not include input and output buffers and is not configured as an oscillator. Instead, the delay chain is made part of the signal chain of an on-chip pulse generator. The duration of the pulse is measured on-chip and taken to equal the delay.

Integrable microwave filter based on a photonic crystal delay line.

PubMed

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

2012-01-01

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

A planar transmission-line sensor for measuring the microwave permittivity of liquid and semisolid biological materials

USDA-ARS?s Scientific Manuscript database

A planar transmission-line configuration for rapid, nondestructive, wideband permittivity measurements of liquid and semisolid materials at microwave frequencies is described. The transmission-line propagation constant of the proposed configuration is determined with the multiline technique from sca...

Medial temporal lobe contributions to short-term memory for faces.

PubMed

Race, Elizabeth; LaRocque, Karen F; Keane, Margaret M; Verfaellie, Mieke

2013-11-01

The role of the medial temporal lobes (MTL) in short-term memory (STM) remains a matter of debate. Whereas imaging studies commonly show hippocampal activation during short-delay memory tasks, evidence from amnesic patients with MTL lesions is mixed. It has been argued that apparent STM impairments in amnesia may reflect long-term memory (LTM) contributions to performance. We challenge this conclusion by demonstrating that MTL amnesic patients show impaired delayed matching-to-sample (DMS) for faces in a task that meets both a traditional delay-based and a recently proposed distractor-based criterion for classification as an STM task. In Experiment 1, we demonstrate that our face DMS task meets the proposed distractor-based criterion for STM classification, in that extensive processing of delay-period distractor stimuli disrupts performance of healthy individuals. In Experiment 2, MTL amnesic patients with lesions extending into anterior subhippocampal cortex, but not patients with lesions limited to the hippocampus, show impaired performance on this task without distraction at delays as short as 8 s, within temporal range of delay-based STM classification, in the context of intact perceptual matching performance. Experiment 3 provides support for the hypothesis that STM for faces relies on configural processing by showing that the extent to which healthy participants' performance is disrupted by interference depends on the configural demands of the distractor task. Together, these findings are consistent with the notion that the amnesic impairment in STM for faces reflects a deficit in configural processing associated with subhippocampal cortices and provide novel evidence that the MTL supports cognition beyond the LTM domain. PsycINFO Database Record (c) 2013 APA, all rights reserved.

On-line estimation and compensation of measurement delay in GPS/SINS integration

NASA Astrophysics Data System (ADS)

Yang, Tao; Wang, Wei

2008-10-01

The chief aim of this paper is to propose a simple on-line estimation and compensation method of GPS/SINS measurement delay. The causes of time delay for GPS/SINS integration are analyzed in this paper. New Kalman filter state equations augmented by measurement delay and modified measurement equations are derived. Based on an open-loop Kalman filter, several simulations are run, results of which show that by the proposed method, the estimation and compensation error of measurement delay is below 0.1s.

Socio-economic status influences access to second-line disease modifying treatment in Relapsing Remitting Multiple Sclerosis patients

PubMed Central

Dejardin, Olivier; Droulon, Karine; Launoy, Guy; Defer, Gilles

2018-01-01

Objective In MS, Socio-Economic status (SES) may influence healthcare and access to disease-modifying treatments (DMTs). Optimising delays to switch patients to a second-line DMT may hamper disease progression most effectively and achieve long term disease control. The objective of this study is to identify the influence of SES on the delay between first and second line DMT in RRMS patients, in Western-Normandy, France. Methods The association between SES and the delay to access a second-line DMT were studied using data from the MS registry of Western-Normandy including 733 patients with a diagnosis of RRMS during the period in question [1982–2011]. We used the European Deprivation Index (EDI), a score with a rank level inversely related to SES. We performed multivariate adjusted Cox models for studying EDI effect on the delay between first and second line DMT. Results No significant influence of SES was observed on delay to access a second-line DMT if first-line DMT exposure time was less than 5 years. After 5 years from initiation of first-line treatment the risk of accessing a second-line DMT is 3 times higher for patients with lower deprivation indices (1st quintile of EDI) ([HR] 3.14 95%CI [1.72–5.72], p-value<0.001) compared to patients with higher values (EDI quintiles 2 to 5). Interpretation In RRMS, a high SES may facilitate access to a second-line DMT a few years after first-line DMT exposure. Greater consideration should also be given to the SES of MS patients as a risk factor in therapeutic healthcare issues throughout medical follow-up. PMID:29390025

Flow Characteristics and Status of CFD Hydrodynamic Model Development in Sudden Contraction Manifold/Orifice Configurations

DTIC Science & Technology

2011-07-01

Branching Configuration 33 6.6 CONTRACTION COEFFICIENT 35 7.0 SUPERCAVITATION 36 7.1 FLOW REATTACHMENT 36 7.1.1 In-Line... SUPERCAVITATION 37 7.2.1 In-Line Configuration Critical Cavitation 37 7.2.2 Dead Head Configuration Critical Cavitation 38 7.2.3 Approach...regimes are: (1) Non-Cavitation, (2) Inception of Cavitation, (3) Full Cavitation, (4) Supercavitation , and (5) Hydraulic Flip. The flow

Line length dependencies in interconnect optimization

NASA Astrophysics Data System (ADS)

Kadoch, Daniel; Duane, Michael; Lee, Yohan

1997-09-01

Metal line delay has become increasingly important for ULSI devices. Numerous expressions and software tools have been developed to describe interconnect delay as a function of the geometry and layout. Although many of these formulas have line length effects, this has not been explored in depth. Most software tools are either geared towards circuit designers, or involve more complex and CPU-intensive 3D modeling. In this work, PISCES (a 2D device simulator) was used to extract metal capacitance per unit length. We extend this approach for various lengths by creating a ladder network of the RC components and simulating in SPICE, or using simple closed-form Elmore delay equations. A new key result is that there are optimum metal line width/space for a fixed pitch and height/space ratios that are metal length dependent. For metal lines shorter than about 1500 micrometers , it is better to have narrower metal lines, and for lengths less than 500 micrometers , shrinking metal height is desirable because the penalty in resistance is more than compensated by the decrease in capacitance. For longer lines, the time delay is dominated by resistance, and wider, taller lines are better. Increasing metal spacing or reducing dielectric constant were beneficial for both long and short metal lines.

Optical phased array configuration for an extremely large telescope.

PubMed

Meinel, Aden Baker; Meinel, Marjorie Pettit

2004-01-20

Extremely large telescopes are currently under consideration by several groups in several countries. Extrapolation of current technology up to 30 m indicates a cost of over dollars 1 billion. Innovative concepts are being explored to find significant cost reductions. We explore the concept of an Optical Phased Array (OPA) telescope. Each element of the OPA is a separate Cassegrain telescope. Collimated beams from the array are sent via an associated set of delay lines to a central beam combiner. This array of small telescope elements offers the possibility of starting with a low-cost array of a few rings of elements, adding structure and additional Cass elements until the desired diameter telescope is attained. We address the salient features of such an extremely large telescope and cost elements relative to more conventional options.

Physics Goals for the Planned Next Linear Collider Engineering Test Facility

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

Raubenheimer, Tor O

2001-10-02

The Next Linear Collider (NLC) Collaboration is planning to construct an Engineering Test Facility (ETF) at Fermilab. As presently envisioned, the ETF would comprise a fundamental unit of the NLC main linac to include X-band klystrons and modulators, a delay-line power-distribution system (DLDS), and NLC accelerating structures that serve as loads. The principal purpose of the ETF is to validate stable operation of the power-distribution system, first without beam, then with a beam having the NLC pulse structure. This paper concerns the possibility of configuring and using the ETF to accelerate beam with an NLC pulse structure, as well asmore » of doing experiments to measure beam-induced wakefields in the rf structures and their influence back on the beam.« less

Physics goals for the planned next linear collider engineering test facility

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

Courtlandt L Bohn et al.

2001-06-26

The Next Linear Collider (NLC) Collaboration is planning to construct an Engineering Test Facility (ETF) at Fermilab. As presently envisioned, the ETF would comprise a fundamental unit of the NLC main linac to include X-band klystrons and modulators, a delay-line power-distribution system (DLDS), and NLC accelerating structures that serve as loads. The principal purpose of the ETF is to validate stable operation of the power-distribution system, first without beam, then with a beam having the NLC pulse structure. This paper concerns the possibility of configuring and using the ETF to accelerate beam with an NLC pulse structure, as well asmore » of doing experiments to measure beam-induced wakefields in the rf structures and their influence back on the beam.« less

Physics goals for the planned next linear collider engineering test facility.

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

Bohn, C.; Michelotti, L.; Ostiguy, J.-F.

2001-07-17

The Next Linear Collider (NLC) Collaboration is planning to construct an Engineering Test Facility (ETF) at Fermilab. As presently envisioned, the ETF would comprise a fundamental unit of the NLC main linac to include X-band klystrons and modulators, a delay-line power-distribution system (DLDS), and NLC accelerating structures that serve as loads. The principal purpose of the ETF is to validate stable operation of the power-distribution system, first without beam, then with a beam having the NLC pulse structure. This paper concerns the possibility of configuring and using the ETF to accelerate beam with an NLC pulse structure, as well asmore » of doing experiments to measure beam-induced wakefields in the rf structures and their influence back on the beam.« less

Suppression of shunting current in a magnetically insulated coaxial vacuum diode

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

Yalandin, M. I.; Sharypov, K. A.; Shpak, V. G.

2015-06-08

Real-time investigations of the dynamics of explosive electron emission from a high-voltage cathode holder made of nonmagnetic stainless steel in a magnetically insulated coaxial vacuum diode have been performed. It has been shown that aging the cathode with several tens of voltage pulses at a field of 1–2 MV/cm provides a stray emission delay ranging from hundreds of picoseconds to a nanosecond or more. In addition, the magnetic field must be configured so that the magnetic lines would not cross the vacuum gap between the diode case and the cathode holder in the region behind the emitting edge of themore » cathode. These efforts provide conditions for stable emission of the working beam from a graphite cathode with a sharp emitting edge.« less

The VLTI: An Ever Improving Imaging Machine

NASA Astrophysics Data System (ADS)

Merand, Antoine

2018-04-01

The last decade has seen VLTI transitioning from 2 to 3 to 4 Telescopes recombination. This led to an increase in the morphological complexity observations are able to address, and ultimately the possibility to reconstruct images. Reconstructing images using 4T data only is not a simple feat and requires coordinated observations with multiple re-configurations of VLTI moving telescopes, the Auxiliary Telescopes (AT). Whereas the current second generation instruments (GRAVITY and MATISSE) combine the 4 currently available telescopes, the VLTI platform can accommodate many more telescopes, and the tunnel has space for 2 more delay lines, allowing to combine simultaneously up to 8 telescopes. I will have a look at how VLTI could evolve to include and operate additional telescopes, as well as the improvements (and limitations) related to imaging stellar surfaces.

VLSI Implementation of a 2.8 Gevent/s Packet-Based AER Interface with Routing and Event Sorting Functionality

PubMed Central

Scholze, Stefan; Schiefer, Stefan; Partzsch, Johannes; Hartmann, Stephan; Mayr, Christian Georg; Höppner, Sebastian; Eisenreich, Holger; Henker, Stephan; Vogginger, Bernhard; Schüffny, Rene

2011-01-01

State-of-the-art large-scale neuromorphic systems require sophisticated spike event communication between units of the neural network. We present a high-speed communication infrastructure for a waferscale neuromorphic system, based on application-specific neuromorphic communication ICs in an field programmable gate arrays (FPGA)-maintained environment. The ICs implement configurable axonal delays, as required for certain types of dynamic processing or for emulating spike-based learning among distant cortical areas. Measurements are presented which show the efficacy of these delays in influencing behavior of neuromorphic benchmarks. The specialized, dedicated address-event-representation communication in most current systems requires separate, low-bandwidth configuration channels. In contrast, the configuration of the waferscale neuromorphic system is also handled by the digital packet-based pulse channel, which transmits configuration data at the full bandwidth otherwise used for pulse transmission. The overall so-called pulse communication subgroup (ICs and FPGA) delivers a factor 25–50 more event transmission rate than other current neuromorphic communication infrastructures. PMID:22016720

The manufacturing, assembly and acceptance testing of the breadboard cryogenic Optical Delay Line for DARWIN

NASA Astrophysics Data System (ADS)

van den Dool, T. C.; Kamphues, F.; Gielesen, W.; Dorrepaal, M.; Doelman, N.; Loix, N.; Verschueren, J. P.; Kooijman, P. P.; Visser, M.; Velsink, G.; Fleury, K.

2005-08-01

TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has developed a compact breadboard cryogenic Optical Delay Line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard delay line is representative of a future flight mechanism, with all used materials and processes being flight representative. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat's eye. Magnetic bearings are used for guiding. They provide frictionless and wear free operation with zero-hysteresis. The manufacturing, assembly and acceptance testing have been completed and are reported in this paper. The verification program, including functional testing at 40 K, will start in the final quarter of 2005.

A Combinatorial Grassmannian Representation of the Magic Three-Qubit Veldkamp Line

NASA Astrophysics Data System (ADS)

Saniga, Metod

2017-10-01

It is demonstrated that the magic three-qubit Veldkamp line occurs naturally within the Veldkamp space of combinatorial Grassmannian of type $G_2(7)$, $\\mathcal{V}(G_2(7))$. The lines of the ambient symplectic polar space are those lines of $\\mathcal{V}(G_2(7))$ whose cores feature an odd number of points of $G_2(7)$. After introducing basic properties of three different types of points and six distinct types of lines of $\\mathcal{V}(G_2(7))$, we explicitly show the combinatorial Grassmannian composition of the magic Veldkamp line; we first give representatives of points and lines of its core generalized quadrangle GQ$(2,2)$, and then additional points and lines of a specific elliptic quadric $\\mathcal{Q}^{-}$(5,2), a hyperbolic quadric $\\mathcal{Q}^{+}$(5,2) and a quadratic cone $\\widehat{\\mathcal{Q}}$(4,2) that are centered on the GQ$(2,2)$. In particular, each point of $\\mathcal{Q}^{+}$(5,2) is represented by a Pasch configuration and its complementary line, the (Schl\\"afli) double-six of points in $\\mathcal{Q}^{-}$(5,2) comprise six Cayley-Salmon configurations and six Desargues configurations with their complementary points, and the remaining Cayley-Salmon configuration stands for the vertex of $\\widehat{\\mathcal{Q}}$(4,2).

Loaded delay lines for future RF pulse compression systems

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

Jones, R.M.; Wilson, P.B.; Kroll, N.M.

1995-05-01

The peak power delivered by the klystrons in the NLCRA (Next Linear Collider Test Accelerator) now under construction at SLAC is enhanced by a factor of four in a SLED-II type of R.F. pulse compression system (pulse width compression ratio of six). To achieve the desired output pulse duration of 250 ns, a delay line constructed from a 36 m length of circular waveguide is used. Future colliders, however, will require even higher peak power and larger compression factors, which favors a more efficient binary pulse compression approach. Binary pulse compression, however, requires a line whose delay time is approximatelymore » proportional to the compression factor. To reduce the length of these lines to manageable proportions, periodically loaded delay lines are being analyzed using a generalized scattering matrix approach. One issue under study is the possibility of propagating two TE{sub o} modes, one with a high group velocity and one with a group velocity of the order 0.05c, for use in a single-line binary pulse compression system. Particular attention is paid to time domain pulse degradation and to Ohmic losses.« less

Medial joint line bone bruising at MRI complicating acute ankle inversion injury: what is its clinical significance?

PubMed

Chan, V O; Moran, D E; Shine, S; Eustace, S J

2013-10-01

To assess the incidence and clinical significance of medial joint line bone bruising following acute ankle inversion injury. Forty-five patients who underwent ankle magnetic resonance imaging (MRI) within 2 weeks of acute ankle inversion injury were included in this prospective study. Integrity of the lateral collateral ligament complex, presence of medial joint line bone bruising, tibio-talar joint effusion, and soft-tissue swelling were documented. Clinical follow-up at 6 months was carried out to determine the impact of injury on length of time out of work, delay in return to normal walking, delay in return to sports activity, and persistence of medial joint line pain. Thirty-seven patients had tears of the anterior talofibular ligament (ATFL). Twenty-six patients had medial joint line bone bruising with altered marrow signal at the medial aspect of the talus and congruent surface of the medial malleolus. A complete ATFL tear was seen in 92% of the patients with medial joint line bone bruising (p = 0.05). Patients with an ATFL tear and medial joint line bone bruising had a longer delay in return to normal walking (p = 0.0002), longer delay in return to sports activity (p = 0.0001), and persistent medial joint line pain (p = 0.0003). There was no statistically significant difference in outcome for the eight patients without ATFL tears. Medial joint line bone bruising following an acute ankle inversion injury was significantly associated with a complete ATFL tear, longer delay in the return to normal walking and sports activity, as well as persistent medial joint line pain. Its presence should prompt detailed assessment of the lateral collateral ligament complex, particularly the ATFL. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

The ACT Vision Mission Study Simulation Effort

NASA Astrophysics Data System (ADS)

Wunderer, C. B.; Kippen, R. M.; Bloser, P. F.; Boggs, S. E.; McConnell, M. L.; Hoover, A.; Oberlack, U.; Sturner, S.; Tournear, D.; Weidenspointner, G.; Zoglauer, A.

2004-12-01

The Advanced Compton Telescope (ACT) has been selected by NASA for a one-year "Vision Mission" study. The main goal of this study is to determine feasible instrument configurations to achieve ACT's sensitivity requirements, and to give recommendations for technology development. Space-based instruments operating in the energy range of nuclear lines are subject to complex backgrounds generated by cosmic-ray interactions and diffuse gamma rays; typically measurements are significantly background-dominated. Therefore accurate, detailed simulations of the background induced in different ACT configurations, and exploration of event selection and reconstruction techniques for reducing these backgrounds, are crucial to determining both the capabilities of a given instrument configuration and the technology enhancements that would result in the most significant performance improvements. The ACT Simulation team has assembled a complete suite of tools that allows the generation of particle backgrounds for a given orbit (based on CREME96), their propagation through any instrument and spacecraft geometry (using MGGPOD) - including delayed photon emission from instrument activation - as well as the event selection and reconstruction of Compton-scatter events in the given detectors (MEGAlib). The package can deal with polarized photon beams as well as e.g. anticoincidence shields. We will report on the progress of the ACT simulation effort and the suite of tools used. We thank Elena Novikova at NRL for her contributions, and NASA for support of this research.

The Role of Configural Processing in Face Classification by Race: An ERP Study

PubMed Central

Lv, Jing; Yan, Tianyi; Tao, Luyang; Zhao, Lun

2015-01-01

The current study investigated the time course of the other-race classification advantage (ORCA) in the subordinate classification of normally configured faces and distorted faces by race. Slightly distorting the face configuration delayed the categorization of own-race faces and had no conspicuous effects on other-race faces. The N170 was sensitive neither to configural distortions nor to faces' races. The P3 was enhanced for other-race than own-race faces and reduced by configural manipulation only for own-race faces. We suggest that the source of ORCA is the configural analysis applied by default while processing own-race faces. PMID:26733850

Nonlinear femtosecond pump-probe spectroscopy using a power-encoded soliton delay line.

PubMed

Saint-Jalm, Sarah; Andresen, Esben Ravn; Bendahmane, Abdelkrim; Kudlinski, Alexandre; Rigneault, Hervé

2016-01-01

We show femtosecond time-resolved nonlinear pump-probe spectroscopy using a fiber soliton as the probe pulse. Furthermore, we exploit soliton dynamics to record an entire transient trace with a power-encoded delay sweep. The power-encoded delay line takes advantage of the dependency of the soliton trajectory in the (λ,z) space upon input power; the difference in accumulated group delay between trajectories converts a fast power sweep into a fast delay sweep. We demonstrate the concept by performing transient absorption spectroscopy in a test sample and validate it against a conventional pump-probe setup.

Synchronization of unidirectionally delay-coupled chaotic oscillators with memory

NASA Astrophysics Data System (ADS)

Jaimes-Reátegui, Rider; Vera-Ávila, Victor P.; Sevilla-Escoboza, Ricardo; Huerta-Cuéllar, Guillermo; Castañeda-Hernández, Carlos E.; Chiu-Zarate, Roger; Pisarchik, Alexander N.

2016-11-01

We study synchronization of two chaotic oscillators coupled with time delay in a master-slave configuration and with delayed positive feedback in the slave oscillator which acts as memory. The dynamics of the slave oscillator is analyzed with bifurcation diagrams of the peak value of the system variable with respect to the coupling and feedback strengths and two delay times. For small coupling, when the oscillators' phases synchronize, memory can induce bistability and stabilize periodic orbits, whereas for stronger coupling it is not possible. The delayed feedback signal impairs synchronization, simultaneously enhancing coherence of the slave oscillator.

Prove Out of Automated Assembly Line for M564 Delay Arming Mechanisms by Acquisition of 40,000 Units Assembled by Automated Line.

DTIC Science & Technology

1981-01-22

Arsenal Contract DUAA25-69-C- 0301 dated 3-10-69 for "Services to design and develop an automated line for assembly of Safety Adapter, Fuze, 1564...determine the line will function at the design rate of 5,000 acceptable assemblies per day and collect production data for incorporation into final...0,000 M564 Delay Arming Mechanisms of the line: Determine that the line will function at the design rate of 5,000. acceotabie asswml I es/day. Collect

Line sensing device for ultrafast laser acoustic inspection using adaptive optics

DOEpatents

Hale, Thomas C.; Moore, David S.

2003-11-04

Apparatus and method for inspecting thin film specimens along a line. A laser emits pulses of light that are split into first, second, third and fourth portions. A delay is introduced into the first portion of pulses and the first portion of pulses is directed onto a thin film specimen along a line. The third portion of pulses is directed onto the thin film specimen along the line. A delay is introduced into the fourth portion of pulses and the delayed fourth portion of pulses are directed to a photorefractive crystal. Pulses of light reflected from the thin film specimen are directed to the photorefractive crystal. Light from the photorefractive crystal is collected and transmitted to a linear photodiode array allowing inspection of the thin film specimens along a line.

Achieving Bidirectional Long Delays In Pulmonary Vein Antral Lines Prior To Bidirectional Block In Patients With Paroxysmal Atrial Fibrillation (The Bi-Bi Technique For Atrial Fibrillation Ablation).

PubMed

Mina, Adel F; Warnecke, Nicholas L

2016-01-01

Background: Pulmonary Vein Antral isolation (PVAI) is currently the standard of care for both paroxysmal and persistent atrial fibrillation ablation. Reconnection to the pulmonary vein is the most common cause of recurrence of atrial fibrillation. Achieving the endpoint of bidirectional block (BDB) for cavotricuspid isthmus dependant flutter has improved our outcomes for atrial flutter ablation. With this we tried to achieve long delays in the pulmonary veins antral lines prior to complete isolation comparable to those delays found in patient with bidirectional block of atrial flutter lines. Study Objective: The objective of this paper was to evaluate feasibility and efficacy of achieving Bidirectional long delays in pulmonary vein antral lines prior to Bidirectional Block in patient with paroxysmal atrial fibrillation. Method: A retrospective analysis was performed on patients who had paroxysmal atrial fibrillation procedures at Unity Point Methodist from January 2015 to January 2016. 20 consecutive patients with paroxysmal atrial fibrillation who had AF ablation using the Bi-Bi technique were evaluated. Result: Mean age was 63, number of antiarrhythmic used prior to ablation was 1.4, mean left atrial size was 38 mm. Mean chads score was 1.3. Mean EF was 53%. Long delays in the left antral circumferential lines were achieved with mean delay of 142 milliseconds +/-100. Also long delays in the right antral circumferential lines were achieved with mean delay of 150 milliseconds +/-80. 95 % (19/20) of patients were free of any atrial arrhythmias and were off antiarrhythmic medications for AF post procedure. There was only one transient complication in one patient who developed a moderate pericardial effusion that was successfully drained with no hemodynamic changes. The only patient who had recurrence was found to have asymptomatic AF with burden on his device <1%, this patient was also found to have non PV triggers for his AF. In patients with only PV triggered AF success rate was 100%. Conclusion: Achievement of Bidirectional long delays in pulmonary vein antral lines prior to Bidirectional Block in patient with paroxysmal atrial fibrillation is feasible and highly effective technique in this small cohort of patients studied. We also outlined the procedure in details.

Apparatus and Method for Communication over Power Lines

NASA Technical Reports Server (NTRS)

Krasowski, Michael J. (Inventor); Prokop, Norman F. (Inventor); Greer, III, Lawrence C. (Inventor); Nappier, Jennifer M. (Inventor)

2017-01-01

An apparatus and method are provided for communicating over power lines. The apparatus includes a coupling modem that is situated between a power line and a device. The coupling modem is configured to demodulate a signal received from the power line into a sine signal and a cosine signal. The coupling modem is also configured to modulate a communicated bit stream received from the device into a transmitted signal in order to impose the transmitted signal onto the power line.

Apparatus and Method for Communication over Power Lines

NASA Technical Reports Server (NTRS)

Krasowski, Michael J. (Inventor); Prokop, Norman F. (Inventor); Greer, Lawrence C., III (Inventor); Nappier, Jennifer M. (Inventor)

2015-01-01

An apparatus and method are provided for communicating over power lines. The apparatus includes a coupling modem that is situated between a power line and a device. The coupling modem is configured to demodulate a signal received from the power line into a sine signal and a cosine signal. The coupling modem is also configured to modulate a communicated bit stream received from the device into a transmitted signal in order to impose the transmitted signal onto the power line.

Phase-locked-loop-based delay-line-free picosecond electro-optic sampling system

NASA Astrophysics Data System (ADS)

Lin, Gong-Ru; Chang, Yung-Cheng

2003-04-01

A delay-line-free, high-speed electro-optic sampling (EOS) system is proposed by employing a delay-time-controlled ultrafast laser diode as the optical probe. Versatile optoelectronic delay-time controllers (ODTCs) based on modified voltage-controlled phase-locked-loop phase-shifting technologies are designed for the laser. The integration of the ODTC circuit and the pulsed laser diode has replaced the traditional optomechanical delay-line module used in the conventional EOS system. This design essentially prevents sampling distortion from misalignment of the probe beam, and overcomes the difficulty in sampling free-running high-speed transients. The maximum tuning range, error, scanning speed, tuning responsivity, and resolution of the ODTC are 3.9π (700°), <5% deviation, 25-2405 ns/s, 0.557 ps/mV, and ˜1 ps, respectively. Free-running wave forms from the analog, digital, and pulsed microwave signals are sampled and compared with those measured by the commercial apparatus.

Method and apparatus for analog pulse pile-up rejection

DOEpatents

De Geronimo, Gianluigi

2013-12-31

A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.

Method and apparatus for analog pulse pile-up rejection

DOEpatents

De Geronimo, Gianluigi

2014-11-18

A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.

Quantitative investigation of the edge enhancement in in-line phase contrast projections and tomosynthesis provided by distributing microbubbles on the interface between two tissues: a phantom study

NASA Astrophysics Data System (ADS)

Wu, Di; Donovan Wong, Molly; Li, Yuhua; Fajardo, Laurie; Zheng, Bin; Wu, Xizeng; Liu, Hong

2017-12-01

The objective of this study was to quantitatively investigate the ability to distribute microbubbles along the interface between two tissues, in an effort to improve the edge and/or boundary features in phase contrast imaging. The experiments were conducted by employing a custom designed tissue simulating phantom, which also simulated a clinical condition where the ligand-targeted microbubbles are self-aggregated on the endothelium of blood vessels surrounding malignant cells. Four different concentrations of microbubble suspensions were injected into the phantom: 0%, 0.1%, 0.2%, and 0.4%. A time delay of 5 min was implemented before image acquisition to allow the microbubbles to become distributed at the interface between the acrylic and the cavity simulating a blood vessel segment. For comparison purposes, images were acquired using three system configurations for both projection and tomosynthesis imaging with a fixed radiation dose delivery: conventional low-energy contact mode, low-energy in-line phase contrast and high-energy in-line phase contrast. The resultant images illustrate the edge feature enhancements in the in-line phase contrast imaging mode when the microbubble concentration is extremely low. The quantitative edge-enhancement-to-noise ratio calculations not only agree with the direct image observations, but also indicate that the edge feature enhancement can be improved by increasing the microbubble concentration. In addition, high-energy in-line phase contrast imaging provided better performance in detecting low-concentration microbubble distributions.

Spatial phase-shift dual-beam speckle interferometry.

PubMed

Gao, Xinya; Yang, Lianxiang; Wang, Yonghong; Zhang, Boyang; Dan, Xizuo; Li, Junrui; Wu, Sijin

2018-01-20

The spatial phase-shift technique has been successfully applied to an out-of-plane speckle interferometry system. Its application to a pure in-plane sensitive system has not been reported yet. This paper presents a novel optical configuration that enables the application of the spatial phase-shift technique to pure in-plane sensitive dual-beam speckle interferometry. The new spatial phase-shift dual-beam speckle interferometry (SPS-DBSP) uses a dual-beam in-plane electronic speckle pattern interferometry configuration with individual aperture shears, avoiding the interference in the object plane by the use of a low-coherence source, and different optical paths. The measured object is illuminated by two incoherent beams that are generated by a delay line, which is larger than the coherence length of the laser. The two beams reflected from the object surface interfere with each other at the CCD plane because of different optical paths. A spatial phase shift is introduced by the angle between the two apertures when they are mapped to the same optical axis. The phase of the in-plane deformation can directly be extracted from the speckle patterns by the Fourier transform method. The capability of SPS-DBSI is demonstrated by theoretical discussion as well as experiments.

Pump-probe micro-spectroscopy by means of an ultra-fast acousto-optics delay line.

PubMed

Audier, Xavier; Balla, Naveen; Rigneault, Hervé

2017-01-15

We demonstrate femtosecond pump-probe transient absorption spectroscopy using a programmable dispersive filter as an ultra-fast delay line. Combined with fast synchronous detection, this delay line allows for recording of 6 ps decay traces at 34 kHz. With such acquisition speed, we perform single point pump-probe spectroscopy on bulk samples in 80 μs and hyperspectral pump-probe imaging over a field of view of 100 μm in less than a second. The usability of the method is illustrated in a showcase experiment to image and discriminate between two pigments in a mixture.

Graphene-based fine-tunable optical delay line for optical beamforming in phased-array antennas.

PubMed

Tatoli, Teresa; Conteduca, Donato; Dell'Olio, Francesco; Ciminelli, Caterina; Armenise, Mario N

2016-06-01

The design of an integrated graphene-based fine-tunable optical delay line on silicon nitride for optical beamforming in phased-array antennas is reported. A high value of the optical delay time (τ_g=920  ps) together with a compact footprint (4.15  mm²) and optical loss <27  dB make this device particularly suitable for highly efficient steering in active phased-array antennas. The delay line includes two graphene-based Mach-Zehnder interferometer switches and two vertically stacked microring resonators between which a graphene capacitor is placed. The tuning range is obtained by varying the value of the voltage applied to the graphene electrodes, which controls the optical path of the light propagation and therefore the delay time. The graphene provides a faster reconfigurable time and low values of energy dissipation. Such significant advantages, together with a negligible beam-squint effect, allow us to overcome the limitations of conventional RF beamformers. A highly efficient fine-tunable optical delay line for the beamsteering of 20 radiating elements up to ±20° in the azimuth direction of a tile in a phased-array antenna of an X-band synthetic aperture radar has been designed.

Design of hybrid optical delay line for automotive radar test system

NASA Astrophysics Data System (ADS)

Son, Byung-Hee; Kim, Kwang-Jin; Li, Ye; Park, Chang-In; Choi, Young-Wan

2015-03-01

In this paper, hybrid optical delay line (HODL) which is demanded on automotive radar test system (RTS) is proposed and demonstrated. HODL is composed with coaxial cable in short delay time (< 32 nsec) and optical fiber in long delay time (>= 32 nsec) which are considering the volume, loss and frequency characteristics. Also, the optical transceiver that has the bandwidth of 1 GHz is designed for frequency modulated continuous wave (FMCW). Experimental results show that the S21 is +/- 0.5 dB in the optical transceiver and +/- 1.7 dB in the whole system at 3.7 GHz ~ 4.7 GHz. The resolution of delay time is 1 ns and the delay flatness is +/- 0.23 ns.

A Low Power Linear Phase Programmable Long Delay Circuit.

PubMed

Rodriguez-Villegas, Esther; Logesparan, Lojini; Casson, Alexander J

2014-06-01

A novel linear phase programmable delay is being proposed and implemented in a 0.35 μm CMOS process. The delay line consists of N cascaded cells, each of which delays the input signal by Td/N, where Td is the total line delay. The delay generated by each cell is programmable by changing a clock frequency and is also fully independent of the frequency of the input signal. The total delay hence depends only on the chosen clock frequency and the total number of cascaded cells. The minimum clock frequency is limited by the maximum time a voltage signal can effectively be held by an individual cell. The maximum number of cascaded cells will be limited by the effects of accumulated offset due to transistor mismatch, which eventually will affect the operating mode of the individual transistors in a cell. This latter limitation has however been dealt with in the topology by having an offset compensation mechanism that makes possible having a large number of cascaded cells and hence a long resulting delay. The delay line has been designed for scalp-based neural activity analysis that is predominantly in the sub-100 Hz frequency range. For these signals, the delay generated by a 31-cell cascade has been demonstrated to be programmable from 30 ms to 3 s. Measurement results demonstrate a 31 stage, 50 Hz bandwidth, 0.3 s delay that operates from a 1.1 V supply with power consumption of 270 nW.

A Novel Component Carrier Configuration and Switching Scheme for Real-Time Traffic in a Cognitive-Radio-Based Spectrum Aggregation System

PubMed Central

Fu, Yunhai; Ma, Lin; Xu, Yubin

2015-01-01

In spectrum aggregation (SA), two or more component carriers (CCs) of different bandwidths in different bands can be aggregated to support a wider transmission bandwidth. The scheduling delay is the most important design constraint for the broadband wireless trunking (BWT) system, especially in the cognitive radio (CR) condition. The current resource scheduling schemes for spectrum aggregation become questionable and are not suitable for meeting the challenge of the delay requirement. Consequently, the authors propose a novel component carrier configuration and switching scheme for real-time traffic (RT-CCCS) to satisfy the delay requirement in the CR-based SA system. In this work, the authors consider a sensor-network-assisted CR network. The authors first introduce a resource scheduling structure for SA in the CR condition. Then the proposed scheme is analyzed in detail. Finally, simulations are carried out to verify the analysis on the proposed scheme. Simulation results prove that our proposed scheme can satisfy the delay requirement in the CR-based SA system. PMID:26393594

A condition for small bootstrap current in three-dimensional toroidal configurations

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

Mikhailov, M. I., E-mail: mikhaylov-mi@nrcki.ru; Nührenberg, J.; Zille, R.

2016-11-15

It is shown that, if the maximum of the magnetic field strength on a magnetic surface in a threedimensional magnetic confinement configuration with stellarator symmetry constitutes a line that is orthogonal to the field lines and crosses the symmetry line, then the bootstrap current density is smaller compared to that in quasi-axisymmetric (qa) [J. Nührenberg et al., in Proc. of Joint Varenna−Lausanne Int. Workshop on Theory of Fusion Plasmas, Varenna, 1994, p. 3] and quasi-helically (qh) symmetric [J. Nührenberg and R. Zille, Phys. Lett. A 129, 113 (1988)] configurations.

A novel shock and heat tolerant gyrosensor utilizing a one-port surface acoustic wave reflective delay line

NASA Astrophysics Data System (ADS)

Oh, Haekwan; Fu, Chen; Yang, Sang Sik; Wang, Wen; Lee, Keekeun

2012-04-01

A surface acoustic wave (SAW)-based gyroscope with an 80 MHz central frequency was fabricated on a 128° YX LiNbO3 piezoelectric substrate. The fabricated gyroscope is composed of a SAW resonator, metallic dots and a SAW reflective delay line. The SAW resonator, which is activated by a voltage-controlled oscillator, generates a stable standing wave with a large amplitude at an 80 MHz resonant frequency, and the metallic dots induce a Coriolis force and generate a secondary SAW in the direction orthogonal to the propagating standing wave. The SAW reflective delay line is employed to measure the Coriolis effect by analyzing the deviations in the resonant frequency of the SAW reflective delay line. A combined finite element method/boundary element method was utilized to extract the optimal device parameters prior to fabrication. The device was fabricated according to the modeling results and then measured on a rate table. When the device was subjected to an angular rotation, a secondary SAW from the vibrating metallic dots was generated owing to the Coriolis force, resulting in a perturbation of the propagating SAW in the SAW reflective delay line. Depending on the angular velocity, the reflection peak of SAW reflective delay line was changed linearly, and this change was measured by the network analyzer. The measured results matched the modeling results well. The obtained sensitivity was approximately 1.23 deg/(deg/s) in an angular rate range of 0-2000 deg s-1. Good thermal and shock stabilities were observed during the evaluation process proving the shock and heat robustness of the fabricated SAW gyroscope.

Improvement of ECM Techniques through Implementation of a Genetic Algorithm

DTIC Science & Technology

2008-03-01

Range Gate Pull-Off (RGPO), where pulse returns are time - delayed to induce an increase in target distance, and Velocity Gate Pull-Off (VGPO), which...estima- tion, the assumption given is that the signal is a stationary, bandlimited process, 13 where the time delay will be fixed for each interval [11...This configuration, known as a transponder system with constant gain, uses time delayed copies of the original to rebroadcast back into the environment

Computer-Drawn Field Lines and Potential Surfaces for a Wide Range of Field Configurations

ERIC Educational Resources Information Center

Brandt, Siegmund; Schneider, Hermann

1976-01-01

Describes a computer program that computes field lines and equipotential surfaces for a wide range of field configurations. Presents the mathematical technique and details of the program, the input data, and different modes of graphical representation. (MLH)

Structural and electronic properties of double-walled boron nitride nanocones

NASA Astrophysics Data System (ADS)

Brito, E.; Silva, T. S.; Guerra, T.; Leite, L.; Azevedo, S.; Freitas, A.; Kaschny, J. R.

2018-01-01

First principles calculations were applied to study the structural and electronic properties of different configurations of double-walled boron nitride nanocones with a disclination angle of 60°. The analysis includes different rotation angles, distance between apexes, as well as distinct types of antiphase boundaries. The calculations indicate that the non-rotated configuration of double-walled nanocone with a defective line composed by C and N atoms, forming C-N bonds, is the most stable configuration. It was found that the yam angle, apexes distance and defective line composition present significant influence on the electronic properties of such structures. Moreover, analyzing the spin charge density, for the electronic states near the Fermi level, it was also found that the configuration with a defective line containing C atoms presents a net magnetic moment.

Project delay analysis of HRSG

NASA Astrophysics Data System (ADS)

Silvianita; Novega, A. S.; Rosyid, D. M.; Suntoyo

2017-08-01

Completion of HRSG (Heat Recovery Steam Generator) fabrication project sometimes is not sufficient with the targeted time written on the contract. The delay on fabrication process can cause some disadvantages for fabricator, including forfeit payment, delay on HRSG construction process up until HRSG trials delay. In this paper, the author is using semi quantitative on HRSG pressure part fabrication delay with configuration plant 1 GT (Gas Turbine) + 1 HRSG + 1 STG (Steam Turbine Generator) using bow-tie analysis method. Bow-tie analysis method is a combination from FTA (Fault tree analysis) and ETA (Event tree analysis) to develop the risk matrix of HRSG. The result from FTA analysis is use as a threat for preventive measure. The result from ETA analysis is use as impact from fabrication delay.

Correlation of Puma airloads: Lifting-line and wake calculation

NASA Technical Reports Server (NTRS)

Bousman, William G.; Young, Colin; Gilbert, Neil; Toulmay, Francois; Johnson, Wayne; Riley, M. J.

1989-01-01

A cooperative program undertaken by organizations in the United States, England, France, and Australia has assessed the strengths and weaknesses of four lifting-line/wake methods and three CFD methods by comparing their predictions with the data obtained in flight trials of a research Puma. The Puma was tested in two configurations: a mixed bladed rotor with instrumented rectangular tip blades, and a configuration with four identical swept tip blades. The results are examined of the lifting-line predictions. The better lifting-line methods show good agreement with lift at the blade tip for the configuration with four swept tips; the moment is well predicted at 0.92 R, but deteriorates outboard. The predictions for the mixed bladed rotor configuration range from fair to good. The lift prediction is better for the swept tip blade than for the rectangular tip blade, but the reasons for this cannot be determined because of the unmodeled effects of the mixed bladed rotor.

Effect of skip row planting configuration on grain sorghum water use

USDA-ARS?s Scientific Manuscript database

Grain sorghum (Sorghum bicolor L. [Moench]) is grown as a dryland crop in the semi-arid Central Great Plains. Growing the crop in a skip row configuration has been proposed as a means of delaying water use during the vegetative stage such that more water will be available to be used during the more ...

Effects of time delay and pitch control sensitivity in the flared landing

NASA Technical Reports Server (NTRS)

Berthe, C. J.; Chalk, C. R.; Wingarten, N. C.; Grantham, W.

1986-01-01

Between December 1985 and January 1986, a flared landing program was conducted, using the USAF Total In-Flight simulator airplane, to examine time delay effects in a formal manner. Results show that as pitch sensitivity is increased, tolerance to time delay decreases. With the proper selection of pitch sensitivity, Level I performance was maintained with time delays ranging from 150 milliseconds to greater than 300 milliseconds. With higher sensitivity, configurations with Level I performance at 150 milliseconds degraded to level 2 at 200 milliseconds. When metrics of time delay and pitch sensitivity effects are applied to enhance previously developed predictive criteria, the result is an improved prediction technique which accounts for significant closed loop items.

Long-Term Behavior of Simulated Partial Lead Service Line Replacements

PubMed Central

St. Clair, Justin; Cartier, Clement; Triantafyllidou, Simoni; Clark, Brandi; Edwards, Marc

2016-01-01

Abstract In this 48-month pilot study, long-term impacts of copper:lead galvanic connections on lead release to water were assessed without confounding differences in pipe exposure prehistory or disturbances arising from cutting lead pipe. Lead release was tracked from three lead service line configurations, including (1) 100% lead, (2) traditional partial replacement with 50% copper upstream of 50% lead, and (3) 50% lead upstream of 50% copper as a function of flow rate, connection types, and sampling methodologies. Elevated lead from galvanic corrosion worsened with time, with 140% more lead release from configurations representing traditional partial replacement configurations at 14 months compared to earlier data in the first 8 months. Even when sampled consistently at moderate flow rate (8 LPM) and collecting all water passing through service lines, conditions representing traditional partial service line configurations were significantly worse (≈40%) when compared to 100% lead pipe. If sampled at a high flow rate (32 LPM) and collecting 2 L samples from service lines, 100% of samples collected from traditional partial replacement configurations exceeded thresholds posing an acute health risk versus a 0% risk for samples from 100% lead pipe. Temporary removal of lead accumulations near Pb:Cu junctions and lead deposits from other downstream plastic pipes reduced risk of partial replacements relative to that observed for 100% lead. When typical brass compression couplings were used to connect prepassivated lead pipes, lead release spiked up to 10 times higher, confirming prior concerns raised at bench and field scale regarding adverse impacts of crevices and service line disturbances on lead release. To quantify semirandom particulate lead release from service lines in future research, whole-house filters have many advantages compared to other approaches. PMID:26989344

Edge Effects in Line Intersect Sampling With

Treesearch

David L. R. Affleck; Timothy G. Gregoire; Harry T. Valentine

2005-01-01

Transects consisting of multiple, connected segments with a prescribed configuration are commonly used in ecological applications of line intersect sampling. The transect configuration has implications for the probability with which population elements are selected and for how the selection probabilities can be modified by the boundary of the tract being sampled. As...

Design unbiased estimation in line intersect sampling using segmented transects

Treesearch

David L.R. Affleck; Timothy G. Gregoire; Harry T. Valentine; Harry T. Valentine

2005-01-01

In many applications of line intersect sampling. transects consist of multiple, connected segments in a prescribed configuration. The relationship between the transect configuration and the selection probability of a population element is illustrated and a consistent sampling protocol, applicable to populations composed of arbitrarily shaped elements, is proposed. It...

VERNIER CHRONOTRON UTILIZING AT LEAST TWO SHORTED DELAY LINES

DOEpatents

Rufer, R.P.

1964-02-25

An improved vernier chronotron featuring pulse-forming circuits of a ringing'' or back and forth'' oscillatory type is described. A delay line shorted at both ends together with transistor circuitry to introduce a pulse into that line and also to provide reinforcement of the pulse as it oscillates between the pulse-reflective extremities is provided. A transistorized coincidence circuit is also provided. Enhanced measurement of time intervals in the nanosecond range is afforded. (AEC)

Neutron-flux profile monitor for use in a fission reactor

DOEpatents

Kopp, M.K.; Valentine, K.H.

1981-09-15

A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occurred. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Neutron flux profile monitor for use in a fission reactor

DOEpatents

Kopp, Manfred K.; Valentine, Kenneth H.

1983-01-01

A neutron flux monitor is provided which consists of a plurality of fission counters arranged as spaced-apart point detectors along a delay line. As a fission event occurs in any one of the counters, two delayed current pulses are generated at the output of the delay line. The time separation of the pulses identifies the counter in which the particular fission event occured. Neutron flux profiles of reactor cores can be more accurately measured as a result.

Non-contact thickness measurement using UTG

NASA Technical Reports Server (NTRS)

Bui, Hoa T. (Inventor)

1996-01-01

A measurement structure for determining the thickness of a specimen without mechanical contact but instead employing ultrasonic waves including an ultrasonic transducer and an ultrasonic delay line connected to the transducer by a retainer or collar. The specimen, whose thickness is to be measured, is positioned below the delay line. On the upper surface of the specimen a medium such as a drop of water is disposed which functions to couple the ultrasonic waves from the delay line to the specimen. A receiver device, which may be an ultrasonic thickness gauge, receives reflected ultrasonic waves reflected from the upper and lower surface of the specimen and determines the thickness of the specimen based on the time spacing of the reflected waves.

A high-resolution time-to-digital converter using a three-level resolution

NASA Astrophysics Data System (ADS)

Dehghani, Asma; Saneei, Mohsen; Mahani, Ali

2016-08-01

In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.

Subwavelength grating enabled on-chip ultra-compact optical true time delay line

PubMed Central

Wang, Junjia; Ashrafi, Reza; Adams, Rhys; Glesk, Ivan; Gasulla, Ivana; Capmany, José; Chen, Lawrence R.

2016-01-01

An optical true time delay line (OTTDL) is a basic photonic building block that enables many microwave photonic and optical processing operations. The conventional design for an integrated OTTDL that is based on spatial diversity uses a length-variable waveguide array to create the optical time delays, which can introduce complexities in the integrated circuit design. Here we report the first ever demonstration of an integrated index-variable OTTDL that exploits spatial diversity in an equal length waveguide array. The approach uses subwavelength grating waveguides in silicon-on-insulator (SOI), which enables the realization of OTTDLs having a simple geometry and that occupy a compact chip area. Moreover, compared to conventional wavelength-variable delay lines with a few THz operation bandwidth, our index-variable OTTDL has an extremely broad operation bandwidth practically exceeding several tens of THz, which supports operation for various input optical signals with broad ranges of central wavelength and bandwidth. PMID:27457024

Fast time-correlated multi-element photon detector and method

DOEpatents

Hayden, Carl C.; Chandler, David W.; Luong, A. Khai

2007-12-18

Photons emitted from a sample responsive to being excited by laser pulses are directed through a prism onto a photomultiplier tube having several spaced-apart anodes. The prism alters the path of each photon as a function of its wavelength so that the wavelength determines the anode to which the photon is directed. Taps of first and second delay lines that are coupled to respective alternating anodes. When an anode receives the photon, it generates a pulse that propagates through the delay line in opposite directions from its associated tap. A timer determines first and second times from the laser pulse to the pulse reaching the first and second ends of the delay line. The difference between the first and second times corresponds to the wavelength of the emitted photon and the sum of the first and second times corresponds to the emission delay of the emitted photon.

Subwavelength grating enabled on-chip ultra-compact optical true time delay line.

PubMed

Wang, Junjia; Ashrafi, Reza; Adams, Rhys; Glesk, Ivan; Gasulla, Ivana; Capmany, José; Chen, Lawrence R

2016-07-26

An optical true time delay line (OTTDL) is a basic photonic building block that enables many microwave photonic and optical processing operations. The conventional design for an integrated OTTDL that is based on spatial diversity uses a length-variable waveguide array to create the optical time delays, which can introduce complexities in the integrated circuit design. Here we report the first ever demonstration of an integrated index-variable OTTDL that exploits spatial diversity in an equal length waveguide array. The approach uses subwavelength grating waveguides in silicon-on-insulator (SOI), which enables the realization of OTTDLs having a simple geometry and that occupy a compact chip area. Moreover, compared to conventional wavelength-variable delay lines with a few THz operation bandwidth, our index-variable OTTDL has an extremely broad operation bandwidth practically exceeding several tens of THz, which supports operation for various input optical signals with broad ranges of central wavelength and bandwidth.

The nebular spectra of the transitional Type Ia Supernovae 2007on and 2011iv: broad, multiple components indicate aspherical explosion cores

NASA Astrophysics Data System (ADS)

Mazzali, P. A.; Ashall, C.; Pian, E.; Stritzinger, M. D.; Gall, C.; Phillips, M. M.; Höflich, P.; Hsiao, E.

2018-05-01

The nebular-epoch spectrum of the rapidly declining, `transitional' Type Ia supernova (SN) 2007on showed double emission peaks, which have been interpreted as indicating that the SN was the result of the direct collision of two white dwarfs. The spectrum can be reproduced using two distinct emission components, one redshifted and one blueshifted. These components are similar in mass but have slightly different degrees of ionization. They recede from one another at a line-of-sight speed larger than the sum of the combined expansion velocities of their emitting cores, thereby acting as two independent nebulae. While this configuration appears to be consistent with the scenario of two white dwarfs colliding, it may also indicate an off-centre delayed detonation explosion of a near-Chandrasekhar-mass white dwarf. In either case, broad emission line widths and a rapidly evolving light curve can be expected for the bolometric luminosity of the SN. This is the case for both SNe 2007on and 2011iv, also a transitional SN Ia that exploded in the same elliptical galaxy, NGC 1404. Although SN 2011iv does not show double-peaked emission line profiles, the width of its emission lines is such that a two-component model yields somewhat better results than a single-component model. Most of the mass ejected is in one component, however, which suggests that SN 2011iv was the result of the off-centre ignition of a Chandrasekhar-mass white dwarf.

Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers.

PubMed

Chin, Sanghoon; Thévenaz, Luc; Sancho, Juan; Sales, Salvador; Capmany, José; Berger, Perrine; Bourderionnet, Jérôme; Dolfi, Daniel

2010-10-11

We experimentally demonstrate a novel technique to process broadband microwave signals, using all-optically tunable true time delay in optical fibers. The configuration to achieve true time delay basically consists of two main stages: photonic RF phase shifter and slow light, based on stimulated Brillouin scattering in fibers. Dispersion properties of fibers are controlled, separately at optical carrier frequency and in the vicinity of microwave signal bandwidth. This way time delay induced within the signal bandwidth can be manipulated to correctly act as true time delay with a proper phase compensation introduced to the optical carrier. We completely analyzed the generated true time delay as a promising solution to feed phased array antenna for radar systems and to develop dynamically reconfigurable microwave photonic filters.

A mixed-signal implementation of a polychronous spiking neural network with delay adaptation

PubMed Central

Wang, Runchun M.; Hamilton, Tara J.; Tapson, Jonathan C.; van Schaik, André

2014-01-01

We present a mixed-signal implementation of a re-configurable polychronous spiking neural network capable of storing and recalling spatio-temporal patterns. The proposed neural network contains one neuron array and one axon array. Spike Timing Dependent Delay Plasticity is used to fine-tune delays and add dynamics to the network. In our mixed-signal implementation, the neurons and axons have been implemented as both analog and digital circuits. The system thus consists of one FPGA, containing the digital neuron array and the digital axon array, and one analog IC containing the analog neuron array and the analog axon array. The system can be easily configured to use different combinations of each. We present and discuss the experimental results of all combinations of the analog and digital axon arrays and the analog and digital neuron arrays. The test results show that the proposed neural network is capable of successfully recalling more than 85% of stored patterns using both analog and digital circuits. PMID:24672422

A mixed-signal implementation of a polychronous spiking neural network with delay adaptation.

PubMed

Wang, Runchun M; Hamilton, Tara J; Tapson, Jonathan C; van Schaik, André

2014-01-01

We present a mixed-signal implementation of a re-configurable polychronous spiking neural network capable of storing and recalling spatio-temporal patterns. The proposed neural network contains one neuron array and one axon array. Spike Timing Dependent Delay Plasticity is used to fine-tune delays and add dynamics to the network. In our mixed-signal implementation, the neurons and axons have been implemented as both analog and digital circuits. The system thus consists of one FPGA, containing the digital neuron array and the digital axon array, and one analog IC containing the analog neuron array and the analog axon array. The system can be easily configured to use different combinations of each. We present and discuss the experimental results of all combinations of the analog and digital axon arrays and the analog and digital neuron arrays. The test results show that the proposed neural network is capable of successfully recalling more than 85% of stored patterns using both analog and digital circuits.

Solid State Mini-RPV Color Imaging System

DTIC Science & Technology

1975-09-12

completed in the design and construction phase . Con- siderations are now in progress for conducting field tests of the equipment against "real world...Simplified Parallel Injection Configuration 2-21 CID Parallel Injection Configuration 2-23 Element Rate Timing 2-25 Horizontal Input and Phase Line...Timing 2-26 Line Reset /Injection Timing 2-27 Line Rate Timing (Start of Readout) 2-28 Driver A4 Block Diagram 2-31 Element Scan Time Base

Sensitivity of bandpass filters using recirculating delay-line structures

NASA Astrophysics Data System (ADS)

Heyde, Eric C.

1996-12-01

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

Separation control by vortex generator devices in a transonic channel flow

NASA Astrophysics Data System (ADS)

Bur, Reynald; Coponet, Didier; Carpels, Yves

2009-12-01

An experimental study was conducted in a transonic channel to control by mechanical vortex generator devices the strong interaction between a shock wave and a separated turbulent boundary layer. Control devices—co-rotating and counter-rotating vane-type vortex generators—were implemented upstream of the shock foot region and tested both on a steady shock wave and on a forced shock oscillation configurations. The spanwise spacing of vortex generator devices along the channel appeared to be an important parameter to control the flow separation region. When the distance between each device is decreased, the vortices merging is more efficient to reduce the separation. Their placement upstream of the shock wave is determinant to ensure that vortices have mixed momentum all spanwise long before they reach the separation line, so as to avoid separation cells. Then, vortex generators slightly reduced the amplitude of the forced shock wave oscillation by delaying the upstream displacement of the leading shock.

The Work Design Method for Human Friendly

NASA Astrophysics Data System (ADS)

Harada, Narumi; Sasaki, Masatoshi; Ichikawa, Masami

In order to realize “the product life cycle with respect for human nature". we ought to make work design so that work environment should be configured to be sound in mind and body, with due consideration of not only physical but also mental factors from the viewpoint of workers. The former includes too heavy work, unreasonable working posture, local fatigue of the body, the safety, and working comfort, and the latter includes work motivation, work worthiness, stress, etc. For the purpose of evaluating the degree of working comfort and safety at human-oriented production lines, we acknowledged, for the work design, the effectiveness of the work designing technique with working time variation duly considered. And, we formulated a model for a mental factor experienced by workers from the degree of working delays. This study covers a work design technique we developed with the effect of the factor as the value of evaluation.

The optical very large array and its moon-based version

NASA Technical Reports Server (NTRS)

Labeyrie, Antoine

1992-01-01

An Optical Very Large Array (OVLA) is currently in early prototyping stages for ground-based sites, such as Mauna Kea and perhaps the VLT site in Chile. Its concept is also suited for a moon-based interferometer. With a ring of bi-dimensionally mobile telescopes, there is maximal flexibility in the aperture pattern, and no need for delay lines. A circular configuration of many free-flying telescopes, TRIO, is also considered for space interferometers. Finally, the principle of gaseous mirrors may become applicable for moon-based optical arrays. Fifteen years after the first coherent linkage of two optical telescopes, the design of an ambitious imaging array, the OVLA, is now well advanced. Two 1.5 m telescopes have been built and now provide astronomical results. Elements of the OVLA are under construction. Although primarily conceived for ground-based sites, the OVLA structure appears to meet the essential requirements for operation on the Moon.

Atomic Data and Spectral Line Intensities for Be-like Ions

NASA Technical Reports Server (NTRS)

Bhatia, Anand; Landi, E.

2008-01-01

Atomic data and collision rates are needed to model the spectrum of optically thin astrophysical sources. Recent observations from solar instrumentation such as SOH0 and Hinode have revealed the presence of hosts of lines emitted by high-energy configurations from ions belonging to the Be-like to the 0-like isoelectronic sequences. Data for such configurations are often unavailable in the literature. We have started a program to calculate the atomic parameters and rates for the high-energy configurations of Be-like ions of the type ls2.21.nl' where n=3,4,5. We report on the results of this project and on the diagnostic application of the predicted spectral lines.

Integrated configurable equipment selection and line balancing for mass production with serial-parallel machining systems

NASA Astrophysics Data System (ADS)

Battaïa, Olga; Dolgui, Alexandre; Guschinsky, Nikolai; Levin, Genrikh

2014-10-01

Solving equipment selection and line balancing problems together allows better line configurations to be reached and avoids local optimal solutions. This article considers jointly these two decision problems for mass production lines with serial-parallel workplaces. This study was motivated by the design of production lines based on machines with rotary or mobile tables. Nevertheless, the results are more general and can be applied to assembly and production lines with similar structures. The designers' objectives and the constraints are studied in order to suggest a relevant mathematical model and an efficient optimization approach to solve it. A real case study is used to validate the model and the developed approach.

Apparatus for simultaneously disreefing a centrally reefed clustered parachute system

DOEpatents

Johnson, Donald W.

1988-01-01

A single multi-line cutter is connected to each of a cluster of parachutes by a separate short tether line that holds the parachutes, initially reefed by closed loop reefing lines, close to one another. The closed loop reefing lines and tether lines, one from each parachute, are disposed within the cutter to be simultaneously cut by its actuation when a central line attached between the payload and the cutter is stretched upon deployment of the cluster. A pyrotechnic or electronic time delay may be included in the cutter to delay the actual simultaneous cutting of all lines until the clustered parachutes attain a measure of stability prior to being disreefed. A second set of reefing lines and second tether lines may be provided for each parachute, to enable a two-stage, separately timed, step-by-step disreefing.

Apparatus for simultaneously disreefing a centrally reefed clustered parachute system

DOEpatents

Johnson, D.W.

1988-06-21

A single multi-line cutter is connected to each of a cluster of parachutes by a separate short tether line that holds the parachutes, initially reefed by closed loop reefing lines, close to one another. The closed loop reefing lines and tether lines, one from each parachute, are disposed within the cutter to be simultaneously cut by its actuation when a central line attached between the payload and the cutter is stretched upon deployment of the cluster. A pyrotechnic or electronic time delay may be included in the cutter to delay the actual simultaneous cutting of all lines until the clustered parachutes attain a measure of stability prior to being disreefed. A second set of reefing lines and second tether lines may be provided for each parachute, to enable a two-stage, separately timed, step-by-step disreefing. 13 figs.

Enhancing the detection of edges and non-differentiable points in an NMR spectrum using delayed-acquisition.

PubMed

Gong, Zhaoyuan; Walls, Jamie D

2018-02-01

Delayed-acquisition, which is a common technique for improving spectral resolution in Fourier transform based spectroscopies, typically relies upon differences in T 2 relaxation rates that are often due to underlying differences in dynamics and/or complexities of the spin systems being studied. After an acquisition delay, the broad signals from fast T 2 -relaxing species are more suppressed relative to the sharp signals from slow T 2 -relaxing species. In this paper, an alternative source of differential "dephasing" under delayed-acquisition is demonstrated that is based solely upon the mathematical properties of the line shape and is independent of the underlying spin dynamics and/or complexity. Signals associated with frequencies where the line shape either changes sharply and/or is non-differentiable at some finite order dephase at a much slower rate than those signals associated with frequencies where the line shape is smooth. Experiments employing delayed-acquisition to study interfaces in biphasic samples, to measure spatially-dependent longitudinal relaxation, and to highlight sharp features in NMR spectra are presented. Copyright © 2017 Elsevier Inc. All rights reserved.

Enhancing the detection of edges and non-differentiable points in an NMR spectrum using delayed-acquisition

NASA Astrophysics Data System (ADS)

Gong, Zhaoyuan; Walls, Jamie D.

2018-02-01

Delayed-acquisition, which is a common technique for improving spectral resolution in Fourier transform based spectroscopies, typically relies upon differences in T2 relaxation rates that are often due to underlying differences in dynamics and/or complexities of the spin systems being studied. After an acquisition delay, the broad signals from fast T2 -relaxing species are more suppressed relative to the sharp signals from slow T2 -relaxing species. In this paper, an alternative source of differential "dephasing" under delayed-acquisition is demonstrated that is based solely upon the mathematical properties of the line shape and is independent of the underlying spin dynamics and/or complexity. Signals associated with frequencies where the line shape either changes sharply and/or is non-differentiable at some finite order dephase at a much slower rate than those signals associated with frequencies where the line shape is smooth. Experiments employing delayed-acquisition to study interfaces in biphasic samples, to measure spatially-dependent longitudinal relaxation, and to highlight sharp features in NMR spectra are presented.

128 Gb/s TWDM PON system using dispersion-supported transmission method

NASA Astrophysics Data System (ADS)

Bindhaiq, Salem; Zulkifli, Nadiatulhuda; Supa'at, Abusahmah M.; Idrus, Sevia M.; Salleh, M. S.

2017-11-01

Time and wavelength division multiplexed passive optical network (TWDM-PON) trend is considered as the most extraordinary trend of the next generation solution to accommodate exponential traffic growth for converged new services. In this paper, we briefly review recent progress on TWDM-PON system through the use of low cost directly modulated lasers (DMLs) transmission for various line rate transmissions to date. Furthermore, through simulation, we propose and evaluate a cost effective way to upgrade TWDM-PON up to a symmetric capacity of 128 Gb/s using fiber Bragg gratings (FBGs) in optical line terminal (OLT) as a paramount dispersion manager in high speed light-wave systems in both upstream and downstream directions. A low cost and potential chirpless directed modulated grating laser (DMGL) is employed for downstream link and DML with a single delay-interferometer (DI) is employed for upstream link. After illustrating the demonstrated system architecture and configuration, we present the results and analysis to prove the system feasibility. The results show that a successful transmission is achieved over 40 km single mode fiber with a power budget of 33.7 dB, which could support 1:256 splitting ratio.

Large-format high resolution microchannel plate detectors for ultraviolet astronomy

NASA Technical Reports Server (NTRS)

Martin, Christopher

1995-01-01

This report includes work on two types of two-dimensional position-sensitive detectors that were developed in this lab under this award. We worked to develop and optimize the wire-wound helical delay line detector (HDL) in the first and second years. Some early work on the HDL is contained in a paper included as Appendix A. In the second and third years we developed the concept for, then successfully designed and tested, both a lab prototype, and a flight prototype of the first, crossed delay line detector based on two orthogonal serpentine delay lines (SDL). Some of the work on the SDL is contained in a paper included as Appendix B. Appendix C contains copies of the invention report and record.

Fiber-optic delay-line stabilization of heterodyne optical signal generator and method using same

NASA Technical Reports Server (NTRS)

Logan, Ronald T. (Inventor)

1997-01-01

The present invention is a laser heterodyne frequency generator system with a stabilizer for use in the microwave and millimeter-wave frequency ranges utilizing a photonic mixer as a photonic phase detector in a stable optical fiber delay-line. Phase and frequency fluctuations of the heterodyne laser signal generators are stabilized at microwave and millimeter wave frequencies by a delay line system operating as a frequency discriminator. The present invention is free from amplifier and mixer 1/.function. noise at microwave and millimeter-wave frequencies that typically limit phase noise performance in electronic cavity stabilized electronic oscillators. Thus, 1/.function. noise due to conventional mixers is eliminated and stable optical heterodyne generation of electrical signals is achieved.

Dramatic robustness of a multiple delay dispersed interferometer to spectrograph errors: how mixing delays reduces or cancels wavelength drift

NASA Astrophysics Data System (ADS)

Erskine, David J.; Linder, E.; Wishnow, E.; Edelstein, J.; Sirk, M.; Muirhead, P.; Lloyd, J.; Kim, A.

2016-08-01

We describe demonstrations of remarkable robustness to instrumental noises by using a multiple delay externally dispersed interferometer (EDI) on stellar observations at the Hale telescope. Previous observatory EDI demonstrations used a single delay. The EDI (also called "TEDI") boosted the 2,700 resolution of the native TripleSpec NIR spectrograph (950-2450 nm) by as much as 10x to 27,000, using 7 overlapping delays up to 3 cm. We observed superb rejection of fixed pattern noises due to bad pixels, since the fringing signal responds only to changes in multiple exposures synchronous to the applied delay dithering. Remarkably, we observed a 20x reduction of reaction in the output spectrum to PSF shifts of the native spectrograph along the dispersion direction, using our standard processing. This allowed high resolution observations under conditions of severe and irregular PSF drift otherwise not possible without the interferometer. Furthermore, we recently discovered an improved method of weighting and mixing data between pairs of delays that can theoretically further reduce the net reaction to PSF drift to zero. We demonstrate a 350x reduction in reaction to a native PSF shift using a simple simulation. This technique could similarly reduce radial velocity noise for future EDI's that use two delays overlapped in delay space (or a single delay overlapping the native peak). Finally, we show an extremely high dynamic range EDI measurement of our ThAr lamp compared to a literature ThAr spectrum, observing weak features ( 0.001x height of nearest strong line) that occur between the major lines. Because of individuality of each reference lamp, accurate knowledge of its spectrum between the (unfortunately) sparse major lines is important for precision radial velocimetry.

Eddy Current Pulsed Thermography with Different Excitation Configurations for Metallic Material and Defect Characterization.

PubMed

Tian, Gui Yun; Gao, Yunlai; Li, Kongjing; Wang, Yizhe; Gao, Bin; He, Yunze

2016-06-08

This paper reviews recent developments of eddy current pulsed thermography (ECPT) for material characterization and nondestructive evaluation (NDE). Due to the fact that line-coil-based ECPT, with the limitation of non-uniform heating and a restricted view, is not suitable for complex geometry structures evaluation, Helmholtz coils and ferrite-yoke-based excitation configurations of ECPT are proposed and compared. Simulations and experiments of new ECPT configurations considering the multi-physical-phenomenon of hysteresis losses, stray losses, and eddy current heating in conjunction with uniform induction magnetic field have been conducted and implemented for ferromagnetic and non-ferromagnetic materials. These configurations of ECPT for metallic material and defect characterization are discussed and compared with conventional line-coil configuration. The results indicate that the proposed ECPT excitation configurations can be applied for different shapes of samples such as turbine blade edges and rail tracks.

An analog integrated circuit beamformer for high-frequency medical ultrasound imaging.

PubMed

Gurun, Gokce; Zahorian, Jaime S; Sisman, Alper; Karaman, Mustafa; Hasler, Paul E; Degertekin, F Levent

2012-10-01

We designed and fabricated a dynamic receive beamformer integrated circuit (IC) in 0.35-μm CMOS technology. This beamformer IC is suitable for integration with an annular array transducer for high-frequency (30-50 MHz) intravascular ultrasound (IVUS) imaging. The beamformer IC consists of receive preamplifiers, an analog dynamic delay-and-sum beamformer, and buffers for 8 receive channels. To form an analog dynamic delay line we designed an analog delay cell based on the current-mode first-order all-pass filter topology, as the basic building block. To increase the bandwidth of the delay cell, we explored an enhancement technique on the current mirrors. This technique improved the overall bandwidth of the delay line by a factor of 6. Each delay cell consumes 2.1-mW of power and is capable of generating a tunable time delay between 1.75 ns to 2.5 ns. We successfully integrated the fabricated beamformer IC with an 8-element annular array. Experimental test results demonstrated the desired buffering, preamplification and delaying capabilities of the beamformer.

Constructing Hopf bifurcation lines for the stability of nonlinear systems with two time delays

NASA Astrophysics Data System (ADS)

Nguimdo, Romain Modeste

2018-03-01

Although the plethora real-life systems modeled by nonlinear systems with two independent time delays, the algebraic expressions for determining the stability of their fixed points remain the Achilles' heel. Typically, the approach for studying the stability of delay systems consists in finding the bifurcation lines separating the stable and unstable parameter regions. This work deals with the parametric construction of algebraic expressions and their use for the determination of the stability boundaries of fixed points in nonlinear systems with two independent time delays. In particular, we concentrate on the cases for which the stability of the fixed points can be ascertained from a characteristic equation corresponding to that of scalar two-delay differential equations, one-component dual-delay feedback, or nonscalar differential equations with two delays for which the characteristic equation for the stability analysis can be reduced to that of a scalar case. Then, we apply our obtained algebraic expressions to identify either the parameter regions of stable microwaves generated by dual-delay optoelectronic oscillators or the regions of amplitude death in identical coupled oscillators.

Fixed-base simulator study of the effect of time delays in visual cues on pilot tracking performance

NASA Technical Reports Server (NTRS)

Queijo, M. J.; Riley, D. R.

1975-01-01

Factors were examined which determine the amount of time delay acceptable in the visual feedback loop in flight simulators. Acceptable time delays are defined as delays which significantly affect neither the results nor the manner in which the subject 'flies' the simulator. The subject tracked a target aircraft as it oscillated sinusoidally in a vertical plane only. The pursuing aircraft was permitted five degrees of freedom. Time delays of from 0.047 to 0.297 second were inserted in the visual feedback loop. A side task was employed to maintain the workload constant and to insure that the pilot was fully occupied during the experiment. Tracking results were obtained for 17 aircraft configurations having different longitudinal short-period characteristics. Results show a positive correlation between improved handling qualities and a longer acceptable time delay.

Feedwater temperature control methods and systems

DOEpatents

Moen, Stephan Craig; Noonan, Jack Patrick; Saha, Pradip

2014-04-22

A system for controlling the power level of a natural circulation boiling water nuclear reactor (NCBWR) is disclosed. The system, in accordance with an example embodiment of the present invention, may include a controller configured to control a power output level of the NCBWR by controlling a heating subsystem to adjust a temperature of feedwater flowing into an annulus of the NCBWR. The heating subsystem may include a steam diversion line configured to receive steam generated by a core of the NCBWR and a steam bypass valve configured to receive commands from the controller to control a flow of the steam in the steam diversion line, wherein the steam received by the steam diversion line has not passed through a turbine. Additional embodiments of the invention may include a feedwater bypass valve for controlling an amount of flow of the feedwater through a heater bypass line to the annulus.

Hunting stability analysis of high-speed train bogie under the frame lateral vibration active control

NASA Astrophysics Data System (ADS)

Yao, Yuan; Wu, Guosong; Sardahi, Yousef; Sun, Jian-Qiao

2018-02-01

In this paper, we study a multi-objective optimal design of three different frame vibration control configurations and compare their performances in improving the lateral stability of a high-speed train bogie. The existence of the time-delay in the control system and its impact on the bogie hunting stability are also investigated. The continuous time approximation method is used to approximate the time-delay system dynamics and then the root locus curves of the system before and after applying control are depicted. The analysis results show that the three control cases could improve the bogie hunting stability effectively. But the root locus of low- frequency hunting mode of bogie which determinates the system critical speed is different, thus affecting the system stability with the increasing of speed. Based on the stability analysis at different bogie dynamics parameters, the robustness of the control case (1) is the strongest. However, the case (2) is more suitable for the dynamic performance requirements of bogie. For the case (1), the time-delay over 10 ms may lead to instability of the control system which will affect the bogie hunting stability seriously. For the case (2) and (3), the increasing time-delay reduces the hunting stability gradually over the high-speed range. At a certain speed, such as 200 km/h, an appropriate time-delay is favourable to the bogie hunting stability. The mechanism is proposed according to the root locus analysis of time-delay system. At last, the nonlinear bifurcation characteristics of the bogie control system are studied by the numerical integration methods to verify the effects of these active control configurations and the delay on the bogie hunting stability.

Ultra-wideband receiver

DOEpatents

McEwan, Thomas E.

1994-01-01

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

Ultra-wideband receiver

DOEpatents

McEwan, Thomas E.

1996-01-01

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, .+-.UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals.

Temporal variations of electron density and temperature in Kr/Ne/H2 photoionized plasma induced by nanosecond pulses from extreme ultraviolet source

NASA Astrophysics Data System (ADS)

Saber, I.; Bartnik, A.; Wachulak, P.; Skrzeczanowski, W.; Jarocki, R.; Fiedorowicz, H.

2017-06-01

Spectral investigations of low-temperature photoionized plasmas created in a Kr/Ne/H2 gas mixture were performed. The low-temperature plasmas were generated by gas mixture irradiation using extreme ultraviolet pulses from a laser-plasma source. Emission spectra in the ultraviolet/visible range from the photoionized plasmas contained lines that mainly corresponded to neutral atoms and singly charged ions. Temporal variations in the plasma electron temperature and electron density were studied using different characteristic emission lines at various delay times. Results, based on Kr II lines, showed that the electron temperature decreased from 1.7 to 0.9 eV. The electron densities were estimated using different spectral lines at each delay time. In general, except for the Hβ line, in which the electron density decreased from 3.78 × 1016 cm-3 at 200 ns to 5.77 × 1015 cm-3 at 2000 ns, most of the electron density values measured from the different lines were of the order of 1015 cm-3 and decreased slightly while maintaining the same order when the delay time increased. The time dependences of the measured and simulated intensities of a spectral line of interest were also investigated. The validity of the partial or full local thermodynamic equilibrium (LTE) conditions in plasma was explained based on time-resolved electron density measurements. The partial LTE condition was satisfied for delay times in the 200 ns to 1500 ns range. The results are summarized, and the dominant basic atomic processes in the gas mixture photoionized plasma are discussed.

Pretest Scores Uniquely Predict 1-Year-Delayed Performance in a Simulation-Based Mastery Course for Central Line Insertion.

PubMed

Diederich, Emily; Thomas, Laura; Mahnken, Jonathan; Lineberry, Matthew

2018-06-01

Within simulation-based mastery learning (SBML) courses, there is inconsistent inclusion of learner pretesting, which requires considerable resources and is contrary to popular instructional frameworks. However, it may have several benefits, including its direct benefit as a form of deliberate practice and its facilitation of more learner-specific subsequent deliberate practice. We consider an unexplored potential benefit of pretesting: its ability to predict variable long-term learner performance. Twenty-seven residents completed an SBML course in central line insertion. Residents were tested on simulated central line insertion precourse, immediately postcourse, and after between 64 and 82 weeks. We analyzed pretest scores' prediction of delayed test scores, above and beyond prediction by program year, line insertion experiences in the interim, and immediate posttest scores. Pretest scores related strongly to delayed test scores (r = 0.59, P = 0.01; disattenuated ρ = 0.75). The number of independent central lines inserted also related to year-delayed test scores (r = 0.44, P = 0.02); other predictors did not discernibly relate. In a regression model jointly predicting delayed test scores, pretest was a significant predictor (β = 0.487, P = 0.011); number of independent insertions was not (β = 0.234, P = 0.198). This study suggests that pretests can play a major role in predicting learner variance in learning gains from SBML courses, thus facilitating more targeted refresher training. It also exposes a risk in SBML courses that learners who meet immediate mastery standards may be incorrectly assumed to have equal long-term learning gains.

75 FR 78928 - Limited Service Domestic Voyage Load Lines for River Barges on Lake Michigan, Delay of Effective...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-17

... Advisories may also be issued when lake ice exists that could be hazardous to small boats. Although river...-AA17 Limited Service Domestic Voyage Load Lines for River Barges on Lake Michigan, Delay of Effective... Lake Michigan. This rule finalized interim regulations that have been in effect since 2002, with some...

Atomic clouds as spectrally selective and tunable delay lines for single photons from quantum dots

NASA Astrophysics Data System (ADS)

Wildmann, Johannes S.; Trotta, Rinaldo; Martín-Sánchez, Javier; Zallo, Eugenio; O'Steen, Mark; Schmidt, Oliver G.; Rastelli, Armando

2015-12-01

We demonstrate a compact, spectrally selective, and tunable delay line for single photons emitted by quantum dots. This is achieved by fine-tuning the wavelength of the optical transitions of such "artificial atoms" into a spectral window in which a cloud of natural atoms behaves as a slow-light medium. By employing the ground-state fine-structure-split exciton confined in an InGaAs/GaAs quantum dot as a source of single photons at different frequencies and the hyperfine-structure-split D1 transition of Cs-vapors as a tunable delay medium, we achieve a differential delay of up 2.4 ns on a 7.5-cm-long path for photons that are only 60 μ eV (14.5 GHz) apart. To quantitatively explain the experimental data, we develop a theoretical model that accounts for both the inhomogeneous broadening of the quantum-dot emission lines and the Doppler broadening of the atomic lines. The concept we proposed here may be used to implement time-reordering operations aimed at erasing the "which-path" information that deteriorates entangled-photon emission from excitons with finite fine-structure splitting.

Effect of applied voltage and inter-pulse delay in spark-assisted LIBS

NASA Astrophysics Data System (ADS)

Robledo-Martinez, A.; Sobral, H.; Garcia-Villarreal, A.

2018-06-01

We report the results obtained in an investigation on the effect of the time delay between the laser and electrical pulses in a spark-assisted laser-induced breakdown spectroscopy (LIBS) experiment. The electrical discharge is produced by the discharge of a charged coaxial cable. This arrangement produces a fast unipolar current pulse (500 ns) that applies high power ( 600 kW) to the laser ablation plasma. The delay between the laser pulse and the electric pulse can be controlled at will in order to find the optimal time in terms of enhancement of the emitted lines. It was found that the application of the high voltage pulse enhances the ionic lines emitted by up to two orders of magnitude. An additional enhancement by a factor of 2-4 can be obtained delaying the application of the electric pulse by a time of 0.6-20 μs. In the tests it was noticed that the ionic lines were found to be clearly responsive to increments in the applied electric energy while the neutral lines did so marginally. Our results show that the intensification of the lines is mainly due to reheating of the ablation plasma as the application of the electrical pulse increments the temperature of the ablation plasma by about 50%. It is demonstrated that the present technique is an efficient way of intensifying the lines emitted without incurring in additional damage to the sample.

Micromachined silicon parallel acoustic delay lines as time-delayed ultrasound detector array for real-time photoacoustic tomography

NASA Astrophysics Data System (ADS)

Cho, Y.; Chang, C.-C.; Wang, L. V.; Zou, J.

2016-02-01

This paper reports the development of a new 16-channel parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT). The PADLs were directly fabricated from single-crystalline silicon substrates using deep reactive ion etching. Compared with other acoustic delay lines (e.g., optical fibers), the micromachined silicon PADLs offer higher acoustic transmission efficiency, smaller form factor, easier assembly, and mass production capability. To demonstrate its real-time photoacoustic imaging capability, the silicon PADL array was interfaced with one single-element ultrasonic transducer followed by one channel of data acquisition electronics to receive 16 channels of photoacoustic signals simultaneously. A PAT image of an optically-absorbing target embedded in an optically-scattering phantom was reconstructed, which matched well with the actual size of the imaged target. Because the silicon PADL array allows a signal-to-channel reduction ratio of 16:1, it could significantly simplify the design and construction of ultrasonic receivers for real-time PAT.

Comparison of divided and full pupil configurations for line-scanning confocal microscopy in human skin and oral mucosa

NASA Astrophysics Data System (ADS)

Larson, Bjorg; Abeytunge, Sanjeewa; Glazowski, Chris; Rajadhyaksha, Milind

2012-02-01

Confocal point-scanning microscopy has been showing promise in the detection, diagnosing and mapping of skin lesions in clinical settings. The noninvasive technique allows provides optical sectioning and cellular resolution for in vivo diagnosis of melanoma and basal cell carcinoma and pre-operative and intra-operative mapping of margins. The imaging has also enabled more accurate "guided" biopsies while minimizing the otherwise large number of "blind" biopsies. Despite these translational advances, however, point-scanning technology remains relatively complex and expensive. Line-scanning technology may offer an alternative approach to accelerate translation to the clinic. Line-scanning, using fewer optical components, inexpensive linear-array detectors and custom electronics, may enable smaller, simpler and lower-cost confocal microscopes. A line is formed using a cylindrical lens and scanned through the back focal plane of the objective with a galvanometric scanner. A linear CCD is used for detection. Two pupil configurations were compared for performance in imaging human tissue. In the full-pupil configuration, illumination and detection is made through the full objective pupil. In the divided pupil approach, half the pupil is illuminated and the other half is used for detection. The divided pupil configuration loses spatial and axial resolution due to a diminished NA, but the sectioning capability and rejection of background is improved. Imaging in skin and oral mucosa illustrate the performance of the two configurations.

Optimal pupil design for confocal microscopy

NASA Astrophysics Data System (ADS)

Patel, Yogesh G.; Rajadhyaksha, Milind; DiMarzio, Charles A.

2010-02-01

Confocal reflectance microscopy may enable screening and diagnosis of skin cancers noninvasively and in real-time, as an adjunct to biopsy and pathology. Current instruments are large, complex, and expensive. A simpler, confocal line-scanning microscope may accelerate the translation of confocal microscopy in clinical and surgical dermatology. A confocal reflectance microscope may use a beamsplitter, transmitting and detecting through the pupil, or a divided pupil, or theta configuration, with half used for transmission and half for detection. The divided pupil may offer better sectioning and contrast. We present a Fourier optics model and compare the on-axis irradiance of a confocal point-scanning microscope in both pupil configurations, optimizing the profile of a Gaussian beam in a circular or semicircular aperture. We repeat both calculations with a cylindrical lens which focuses the source to a line. The variable parameter is the fillfactor, h, the ratio of the 1/e2 diameter of the Gaussian beam to the diameter of the full aperture. The optimal values of h, for point scanning are 0.90 (full) and 0.66 for the half-aperture. For line-scanning, the fill-factors are 1.02 (full) and 0.52 (half). Additional parameters to consider are the optimal location of the point-source beam in the divided-pupil configuration, the optimal line width for the line-source, and the width of the aperture in the divided-pupil configuration. Additional figures of merit are field-of-view and sectioning. Use of optimal designs is critical in comparing the experimental performance of the different configurations.

Configuration-specific kinetic theory applied to an ideal binary gas mixture.

PubMed

Wiseman, Floyd L

2006-10-05

This paper is the second in a two-part series dealing with the configuration-specific analyses for molecular collision events of hard, spherical molecules at thermal equilibrium. The first paper analyzed a single-component system, and the reader is referred to it for the fundamental concepts. In this paper, the expressions for the configuration-specific collision frequencies and the average line-of-centers collision angles and speeds are derived for an ideal binary gas mixture. The analyses show that the average line-of-centers quantities are all dependent upon the ratio of the masses of the two components, but not upon molecular size. Of course, the configuration-specific collision frequencies do depend on molecular size. The expression for the overall binary collision frequency is a simple sum of the configuration-specific collision frequencies and is identical to the conventional expression.

Webcam autofocus mechanism used as a delay line for the characterization of femtosecond pulses.

PubMed

Castro-Marín, Pablo; Kapellmann-Zafra, Gabriel; Garduño-Mejía, Jesús; Rosete-Aguilar, Martha; Román-Moreno, Carlos J

2015-08-01

In this work, we present an electromagnetic focusing mechanism (EFM), from a commercial webcam, implemented as a delay line of a femtosecond laser pulse characterization system. The characterization system consists on a second order autocorrelator based on a two-photon-absorption detection. The results presented here were performed for two different home-made femtosecond oscillators: Ti:sapph @ 820 nm and highly chirped pulses generated with an Erbium Doped Fiber @ 1550 nm. The EFM applied as a delay line represents an excellent alternative due its performance in terms of stability, resolution, and long scan range up to 3 ps. Due its low power consumption, the device can be connected through the Universal Serial Bus (USB) port. Details of components, schematics of electronic controls, and detection systems are presented.

Webcam autofocus mechanism used as a delay line for the characterization of femtosecond pulses

NASA Astrophysics Data System (ADS)

Castro-Marín, Pablo; Kapellmann-Zafra, Gabriel; Garduño-Mejía, Jesús; Rosete-Aguilar, Martha; Román-Moreno, Carlos J.

2015-08-01

In this work, we present an electromagnetic focusing mechanism (EFM), from a commercial webcam, implemented as a delay line of a femtosecond laser pulse characterization system. The characterization system consists on a second order autocorrelator based on a two-photon-absorption detection. The results presented here were performed for two different home-made femtosecond oscillators: Ti:sapph @ 820 nm and highly chirped pulses generated with an Erbium Doped Fiber @ 1550 nm. The EFM applied as a delay line represents an excellent alternative due its performance in terms of stability, resolution, and long scan range up to 3 ps. Due its low power consumption, the device can be connected through the Universal Serial Bus (USB) port. Details of components, schematics of electronic controls, and detection systems are presented.

The recommendation of line-balancing improvement on MCM product line 1 using genetics algorithm and moodie young at XYZ Company, Co.

NASA Astrophysics Data System (ADS)

Sriwana, I. K.; Marie, I. A.; Mangala, D.

2017-12-01

Kencana Gemilang, Co. is one electronics industry engaging in the manufacture sector. This company manufactures and assembles household electronic products, such as rice cooker, fan, iron, blender, etc. The company deals with an issue of underachievement of an established production target on MCM products line 1. This study aimed to calculate line efficiencies, delay times, and initial line smoothness indexes. The research was carried out by means of depicting a precedence diagram and gathering time data of each work element followed by examination and calculation of standard time as well as line balancing using methods of Moodie Young and Generics Algorithm. Based on results of calculation, better line balancing than the existing initial conditions, i.e. improvement in the line efficiency by 18.39%, deterioration in balanced delay by 28.39%, and deterioration of a smoothness index by 23.85% was obtained.

Numerical modelling of multimode fibre-optic communication lines

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

Sidelnikov, O S; Fedoruk, M P; Sygletos, S

The results of numerical modelling of nonlinear propagation of an optical signal in multimode fibres with a small differential group delay are presented. It is found that the dependence of the error vector magnitude (EVM) on the differential group delay can be reduced by increasing the number of ADC samples per symbol in the numerical implementation of the differential group delay compensation algorithm in the receiver. The possibility of using multimode fibres with a small differential group delay for data transmission in modern digital communication systems is demonstrated. It is shown that with increasing number of modes the strong couplingmore » regime provides a lower EVM level than the weak coupling one. (fibre-optic communication lines)« less

Echo Mapping of Active Galactic Nuclei

NASA Technical Reports Server (NTRS)

Peterson, B. M.; Horne, K.

2004-01-01

Echo mapping makes use of the intrinsic variability of the continuum source in active galactic nuclei to map out the distribution and kinematics of line-emitting gas from its light travel time-delayed response to continuum changes. Echo mapping experiments have yielded sizes for the broad line-emitting region in about three dozen AGNs. The dynamics of the line-emitting gas seem to be dominated by the gravity of the central black hole, enabling measurement of the black-hole masses in AGNs. We discuss requirements for future echo-mapping experiments that will yield the high quality velocity-delay maps of the broad-line region that are needed to determine its physical nature.

Employing TDMA Protocol in Neural Nanonetworks in Case of Neuron Specific Faults.

PubMed

Tezcan, Hakan; Oktug, Sema F; Kök, Fatma Neşe

2015-09-01

Many neurodegenerative diseases arise from the malfunctioning neurons in the pathway where the signal is carried. In this paper, we propose neuron specific TDMA/multiplexing and demultiplexing mechanisms to convey the spikes of a receptor neuron over a neighboring path in case of an irreversible path fault existing in its original path. The multiplexing mechanism depends on neural delay box (NDB) which is composed of a relay unit and a buffering unit. The relay unit can be realized as a nanoelectronic device. The buffering unit can be implemented either via neural delay lines as employed in optical switching systems or via nanoelectronic delay lines, i.e., delay flip flops. Demultiplexing is realized by a demultiplexer unit according to the time slot assignment information. Besides, we propose the use of neural interfaces in the NDBs and the demultiplexer unit for detecting and stimulating the generation of spikes. The objective of the proposed mechanisms is to substitute a malfunctioning path, increase the number of spikes delivered and correctly deliver the spikes to the intended part of the somatosensory cortex. The results demonstrate that significant performance improvement on the successively delivered number of spikes is achievable when delay lines are employed as neural buffers in NDBs.

ELF field in the proximity of complex power line configuration measurement procedures.

PubMed

Benes, M; Comelli, M; Villalta, R

2006-01-01

The issue of how to measure magnetic induction fields generated by various power line configurations, when there are several power lines that run across the same exposure area, has become a matter of interest and study within the Regional Environment Protection Agency of Friuli Venezia Giulia. In classifying the various power line typologies the definition of double circuit line was given: in this instance the magnetic field is determined by knowing the electrical and geometric parameters of the line. In the case of independent lines instead, the field is undetermined. It is therefore pointed out how, in the latter case, extracting previsional information from a set of measurements of the magnetic field alone is impossible. Making measurements throughout the territory of service has in several cases offered the opportunity to define standard operational procedures.

Reducing the Handover Delay in FMIPv6 Using Proactive Care-of Address Scheme

NASA Astrophysics Data System (ADS)

Li, Yong; Jin, Depeng; Su, Li; Zeng, Lieguang

To deal with the increasing number of mobile devices accessing the Internet and the increasing demands of mobility management, IETF has proposed Mobile IPv6 and its fast handover protocol FMIPv6. In FMIPv6, the possibility of Care-of Address (CoA) collision and the time for Return Routability (RR) procedure result in long handover delay, which makes it unsuitable for real-time applications. In this paper, we propose an improved handover scheme for FMIPv6, which reduces the handover delay by using proactive CoA acquisition, configuration and test method. In our proposal, collision-free CoA is proactively prepared, and the time for RR procedure does not contribute to the handover delay. Furthermore, we analyze our proposal's benefits and overhead tradeoff. The numerical results demonstrate that it outperforms the current schemes, such as FMIPv6 and enhanced FMIPv6, on the aspect of handover delay and packet transmission delay.

A generic hydrological model for a green roof drainage layer.

PubMed

Vesuviano, Gianni; Stovin, Virginia

2013-01-01

A rainfall simulator of length 5 m and width 1 m was used to supply constant intensity and largely spatially uniform water inflow events to 100 different configurations of commercially available green roof drainage layer and protection mat. The runoff from each inflow event was collected and sampled at one-second intervals. Time-series runoff responses were subsequently produced for each of the tested configurations, using the average response of three repeat tests. Runoff models, based on storage routing (dS/dt = I-Q) and a power-law relationship between storage and runoff (Q = kS(n)), and incorporating a delay parameter, were created. The parameters k, n and delay were optimized to best fit each of the runoff responses individually. The range and pattern of optimized parameter values was analysed with respect to roof and event configuration. An analysis was performed to determine the sensitivity of the shape of the runoff profile to changes in parameter values. There appears to be potential to consolidate values of n by roof slope and drainage component material.

JPRS Report, Science & Technology USSR: Physics & Mathematics.

DTIC Science & Technology

1991-06-06

through a fixed delay line ( Porro prism ) and then a polarizer, the transmitted one passed through an adjustable delay line ( Porro prism ) and then a...radiation emitted by a plasma liner upon its compression into a plasma column. The target is a layer of material forming a resonance -bound ion pair...4.8338 nm wavelength corresponding to the resonance line of the 2s2 2S1/2 —> 3p 2P1/2° transition in the lithium-like A1XI ion pumping the 2s2 ’S0

Continuous angle steering of an optically- controlled phased array antenna based on differential true time delay constituted by micro-optical components.

PubMed

Wang, Jian; Hou, Peipei; Cai, Haiwen; Sun, Jianfeng; Wang, Shunan; Wang, Lijuan; Yang, Fei

2015-04-06

We propose an optically controlled phased array antenna (PAA) based on differential true time delay constructed optical beamforming network (OBFN). Differential true time delay is realized by stack integrated micro-optical components. Optically-controlled angle steering of radio frequency (RF) beams are realized and demonstrated by this configuration. Experimental results demonstrate that OBFN based PAA can accomplish RF-independent broadband beam steering without beam squint effect and can achieve continuous angle steering. In addition, multi-beams for different steering angles are acquired synchronously.

Study on an azimuthal line cusp ion source for the KSTAR neutral beam injector.

PubMed

Jeong, Seung Ho; Chang, Doo-Hee; In, Sang Ryul; Lee, Kwang Won; Oh, Byung-Hoon; Yoon, Byung-Joo; Song, Woo Sob; Kim, Jinchoon; Kim, Tae Seong

2008-02-01

In this study it is found that the cusp magnetic field configuration of an anode bucket influences the primary electron behavior. An electron orbit code (ELEORBIT code) showed that an azimuthal line cusp (cusp lines run azimuthally with respect to the beam extraction direction) provides a longer primary electron confinement time than an axial line cusp configuration. Experimentally higher plasma densities were obtained under the same arc power when the azimuthal cusp chamber was used. The newly designed azimuthal cusp bucket has been investigated in an effort to increase the plasma density in its plasma generator per arc power.

Development of acoustically lined ejector technology for multitube jet noise suppressor nozzles by model and engine tests over a wide range of jet pressure ratios and temperatures

NASA Technical Reports Server (NTRS)

Atvars, J.; Paynter, G. C.; Walker, D. Q.; Wintermeyer, C. F.

1974-01-01

An experimental program comprising model nozzle and full-scale engine tests was undertaken to acquire parametric data for acoustically lined ejectors applied to primary jet noise suppression. Ejector lining design technology and acoustical scaling of lined ejector configurations were the major objectives. Ground static tests were run with a J-75 turbojet engine fitted with a 37-tube, area ratio 3.3 suppressor nozzle and two lengths of ejector shroud (L/D = 1 and 2). Seven ejector lining configurations were tested over the engine pressure ratio range of 1.40 to 2.40 with corresponding jet velocities between 305 and 610 M/sec. One-fourth scale model nozzles were tested over a pressure ratio range of 1.40 to 4.0 with jet total temperatures between ambient and 1088 K. Scaling of multielement nozzle ejector configurations was also studied using a single element of the nozzle array with identical ejector lengths and lining materials. Acoustic far field and near field data together with nozzle thrust performance and jet aerodynamic flow profiles are presented.

Design and Performance of Ka-Band Fiber-Optic Delay Lines

DTIC Science & Technology

2012-12-28

Approved for public release; distribution is unlimited. Vincent J. Urick Joseph M. singley christopher e. sUnderMan John F. diehl keith J...PAGES 17. LIMITATION OF ABSTRACT Design and Performance of Ka-Band Fiber-Optic Delay Lines Vincent J. Urick , Joseph M. Singley, Christopher E...Approved for public release; distribution is unlimited. Unclassified Unlimited Unclassified Unlimited Unclassified Unlimited 64 Vincent J. Urick (202

Control of operating parameters of laser ceilometers with the application of fiber optic delay line imitation

NASA Astrophysics Data System (ADS)

Kim, A. A.; Klochkov, D. V.; Konyaev, M. A.; Mihaylenko, A. S.

2017-11-01

The article considers the problem of control and verification of the laser ceilometers basic performance parameters and describes an alternative method based on the use of multi-length fiber optic delay line, simulating atmospheric track. The results of the described experiment demonstrate the great potential of this method for inspection and verification procedures of laser ceilometers.

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

Feldman, U.; Space Science Division, Naval Research Laboratory, Washington, DC 20375-5320; Doschek, G.A.

We list observed parity-forbidden and spin-forbidden lines in the 500-1600 A range emitted by solar coronal plasmas and derive improved energy levels from their wavelengths. The lines, emitted by astrophysical abundant elements, belong to transitions within the ground configurations of the type ns{sup 2} np {sup k}, for n = 2, 3 and k = 0-5, and between the lowest term of the first excited configuration 2s2p {sup k+1} and the 2s{sup 2}2p {sup k} ground configurations for k = 0, 1, 2. For each line we give the newly measured wavelength, and the measured or predicted wavelength from themore » NIST Atomic Spectra Database (ASD) (which except for a few cases includes the previously reported compilation of Kaufman and Sugar [J. Phys. Chem. Ref. Data 15 (1986) 321]), and the values of the transition probability taken from the ASD and CHIANTI database. The list contains measured wavelengths of 136 lines of which over 100 were not available for the Kaufman and Sugar compilation. In addition we provide energy levels that were derived from the reported lines.« less

Quark-antiquark potential in defect conformal field theory

NASA Astrophysics Data System (ADS)

Preti, Michelangelo; Trancanelli, Diego; Vescovi, Edoardo

2017-10-01

We consider antiparallel Wilson lines in N = 4 super Yang-Mills in the presence of a codimension-1 defect. We compute the Wilson lines' expectation value both at weak coupling, in the gauge theory, and at strong coupling, by finding the string configurations which are dual to this operator. These configurations display a Gross-Ooguri transition between a connected, U-shaped string phase and a phase in which the string breaks into two disconnected surfaces. We analyze in detail the critical configurations separating the two phases and compare the string result with the gauge theory one in a certain double scaling limit.

Factors contributing to the adaptation aftereffects of facial expression.

PubMed

Butler, Andrea; Oruc, Ipek; Fox, Christopher J; Barton, Jason J S

2008-01-29

Previous studies have demonstrated the existence of adaptation aftereffects for facial expressions. Here we investigated which aspects of facial stimuli contribute to these aftereffects. In Experiment 1, we examined the role of local adaptation to image elements such as curvature, shape and orientation, independent of expression, by using hybrid faces constructed from either the same or opposing expressions. While hybrid faces made with consistent expressions generated aftereffects as large as those with normal faces, there were no aftereffects from hybrid faces made from different expressions, despite the fact that these contained the same local image elements. In Experiment 2, we examined the role of facial features independent of the normal face configuration by contrasting adaptation with whole faces to adaptation with scrambled faces. We found that scrambled faces also generated significant aftereffects, indicating that expressive features without a normal facial configuration could generate expression aftereffects. In Experiment 3, we examined the role of facial configuration by using schematic faces made from line elements that in isolation do not carry expression-related information (e.g. curved segments and straight lines) but that convey an expression when arranged in a normal facial configuration. We obtained a significant aftereffect for facial configurations but not scrambled configurations of these line elements. We conclude that facial expression aftereffects are not due to local adaptation to image elements but due to high-level adaptation of neural representations that involve both facial features and facial configuration.

Ultra-wideband receiver

DOEpatents

McEwan, T.E.

1994-09-06

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, [+-] UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals. 16 figs.

Ultra-wideband receiver

DOEpatents

McEwan, T.E.

1996-06-04

An ultra-wideband (UWB) receiver utilizes a strobed input line with a sampler connected to an amplifier. In a differential configuration, {+-}UWB inputs are connected to separate antennas or to two halves of a dipole antenna. The two input lines include samplers which are commonly strobed by a gating pulse with a very low duty cycle. In a single ended configuration, only a single strobed input line and sampler is utilized. The samplers integrate, or average, up to 10,000 pulses to achieve high sensitivity and good rejection of uncorrelated signals. 21 figs.

Magnetic reconnection in collisionless plasmas - Prescribed fields

NASA Technical Reports Server (NTRS)

Burkhart, G. R.; Drake, J. F.; Chen, J.

1990-01-01

The structure of the dissipation region during magnetic reconnection in collisionless plasma is investigated by examining a prescribed two-dimensional magnetic x line configuration with an imposed inductive electric field E(y). The calculations represent an extension of recent MHD simulations of steady state reconnection (Biskamp, 1986; Lee and Fu, 1986) to the collisionless kinetic regime. It is shown that the structure of the x line reconnection configuration depends on only two parameters: a normalized inductive field and a parameter R which represents the opening angle of the magnetic x lines.

Observational Requirements for High-Fidelity Reverberation Mapping

NASA Technical Reports Server (NTRS)

Horne, Keith; Peterson, Bradley M.; Collier, Stefan J.; Netzer, Hagai

2004-01-01

We present a series of simulations to demonstrate that high-fidelity velocity-delay maps of the emission-line regions in active galactic nuclei can be obtained from time-resolved spectrophotometric data sets like those that will arise from the proposed Kronos satellite. While previous reverberation-mapping experiments have established the size scale R of the broad emission-line regions from the mean time delay tau = R/c between the line and continuum variations and have provided strong evidence for supermassive black holes, the detailed structure and kinematics of the broad-line region remain ambiguous and poorly constrained. Here we outline the technical improvements that will be required to successfully map broad-line regions by reverberation techniques. For typical AGN continuum light curves, characterized by power-law power spectra P (f) is proportional to f(exp -alpha) with a = -1.5 +/- 0.5, our simulations show that a small UV/optical spectrometer like Kronos will clearly distinguish between currently viable alternative kinematic models. From spectra sampled at time intervals Delta t and sustained for a total duration T(sub dur), we can reconstruct high-fidelity velocity-delay maps with velocity resolution comparable to that of the spectra, and delay resolution Delta tau approx. 2 Delta t, provided T(sub dur) exceeds the broad-line region light crossing time by at least a factor of three. Even very complicated kinematical models, such as a Keplerian flow with superimposed spiral wave pattern, are resolved in maps from our simulated Kronos datasets. Reverberation mapping with Kronos data is therefore likely deliver the first clear maps of the geometry and kinematics in the broad emission-line regions 1-100 microarcseconds from supermassive black holes.

Results of a space shuttle vehicle ferry configuration afterbody fairing optimization study using a 140A/B 0.0405-scale model orbiter (43-0) in the Rockwell International 7.75 by 11.0 ft low speed wind tunnel (OA124)

NASA Technical Reports Server (NTRS)

Houlihan, S. R.

1975-01-01

Experimental aerodynamic investigations were conducted on a dual-strut mounted 0.0405-scale representation of the 140A/B outer mold line space shuttle orbiter vehicle. The tests, conducted from 11 Oct., 1974 through 22 Oct., 1974, were primarily to investigate aerodynamic stability and control characteristics of the space shuttle orbiter ferry configuration. Four afterbody fairing configurations and various additions to them in the form of horizontal and ventral fins strakes and other aerodynamic protuberances were tested. Base line data on the basic orbiter with MPS nozzles and bodyflap were recorded. The drag of the optimum ferry configuration was increased to the level of the basic orbiter for possible flight test configurations by the addition of two sizes of perforated speed brakes on the tail cone surface.

Webcam autofocus mechanism used as a delay line for the characterization of femtosecond pulses

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

Castro-Marín, Pablo; Kapellmann-Zafra, Gabriel; Garduño-Mejía, Jesús, E-mail: jesus.garduno@ccadet.unam.mx

2015-08-15

In this work, we present an electromagnetic focusing mechanism (EFM), from a commercial webcam, implemented as a delay line of a femtosecond laser pulse characterization system. The characterization system consists on a second order autocorrelator based on a two-photon-absorption detection. The results presented here were performed for two different home-made femtosecond oscillators: Ti:sapph @ 820 nm and highly chirped pulses generated with an Erbium Doped Fiber @ 1550 nm. The EFM applied as a delay line represents an excellent alternative due its performance in terms of stability, resolution, and long scan range up to 3 ps. Due its low powermore » consumption, the device can be connected through the Universal Serial Bus (USB) port. Details of components, schematics of electronic controls, and detection systems are presented.« less

Revival of oscillations from deaths in diffusively coupled nonlinear systems: Theory and experiment

NASA Astrophysics Data System (ADS)

Zou, Wei; Sebek, Michael; Kiss, István Z.; Kurths, Jürgen

2017-06-01

Amplitude death (AD) and oscillation death (OD) are two structurally different oscillation quenching phenomena in coupled nonlinear systems. As a reverse issue of AD and OD, revival of oscillations from deaths attracts an increasing attention recently. In this paper, we clearly disclose that a time delay in the self-feedback component of the coupling destabilizes not only AD but also OD, and even the AD to OD transition in paradigmatic models of coupled Stuart-Landau oscillators under diverse death configurations. Using a rigorous analysis, the effectiveness of this self-feedback delay in revoking AD is theoretically proved to be valid in an arbitrary network of coupled Stuart-Landau oscillators with generally distributed propagation delays. Moreover, the role of self-feedback delay in reviving oscillations from AD is experimentally verified in two delay-coupled electrochemical reactions.

Revival of oscillations from deaths in diffusively coupled nonlinear systems: Theory and experiment.

PubMed

Zou, Wei; Sebek, Michael; Kiss, István Z; Kurths, Jürgen

2017-06-01

Amplitude death (AD) and oscillation death (OD) are two structurally different oscillation quenching phenomena in coupled nonlinear systems. As a reverse issue of AD and OD, revival of oscillations from deaths attracts an increasing attention recently. In this paper, we clearly disclose that a time delay in the self-feedback component of the coupling destabilizes not only AD but also OD, and even the AD to OD transition in paradigmatic models of coupled Stuart-Landau oscillators under diverse death configurations. Using a rigorous analysis, the effectiveness of this self-feedback delay in revoking AD is theoretically proved to be valid in an arbitrary network of coupled Stuart-Landau oscillators with generally distributed propagation delays. Moreover, the role of self-feedback delay in reviving oscillations from AD is experimentally verified in two delay-coupled electrochemical reactions.

Transmission line design for a power distribution system at 20 kHz for aircraft

NASA Technical Reports Server (NTRS)

Zelby, L. W.; Mathes, J. B.; Shawver, J. W.

1986-01-01

A low inductance, low characteristic impedance transmission line was designed for a 20 kHz power distribution system. Several different conductor configurations were considered: strip lines, interdigitated metal ribbons, and standard insulated wires in multiwire configurations (circular and rectangular cylindrical arrangements). The final design was a rectangular arrangement of multiple wires of the same gauge with alternating polarities from wire to wire. This offered the lowest inductance per unit length (on the order of several nanohenries/meter) and the lowest characteristic impedance (on the order of one Ohm). Standard multipin connectors with gold-plated elements were recommended with this transmission line, the junction boxes to be internally connected with flat metal ribbons for low inductance, and the line to be constructed in sections of suitable length. Computer programs for the calculation of inductance of multiwire lines and of capacitances of strip lines were developed.

Enhanced Sensitivity of Novel Surface Acoustic Wave Microelectromechanical System-Interdigital Transducer Gyroscope

NASA Astrophysics Data System (ADS)

Wang, Wen; Oh, Haekwan; Lee, Keekeun; Yoon, Sungjin; Yang, Sangsik

2009-06-01

In this paper, we present a novel microelectromechanical system-interdigital transducer (MEMS-IDT) surface acoustic wave (SAW) gyroscope with an 80 MHz central frequency on a 128° YX LiNbO3 wafer. The developed MEMS-IDT gyroscope is composed of a two-port SAW resonator, a dual delay line oscillator, and metallic dots. The SAW resonator provides a stable standing wave, and the vibrating metallic dot at an antinode of the standing wave induces the second SAW in the normal direction of its vibrating axis. The dual delay line oscillator detects the Coriolis force by comparing the resonant frequencies between two oscillators through the interference effect. The coupling of mode (COM) modeling was used to extract the optimal design parameters prior to fabrication. In the electrical testing by the network analyzer, the fabricated SAW resonator and delay lines showed low insertion loss and similar operation frequencies between a resonator and delay lines. When the device was rotated, the resonant frequency differences between two oscillators linearly varied owing to the Coriolis force. The obtained sensitivity was approximately 119 Hz deg-1 s-1 in the angular rate range of 0-1000 deg/s. Satisfactory linearity and superior directivity were also observed in the test.

Compensating measured intra-wafer ring oscillator stage delay with intra-wafer exposure dose corrections

NASA Astrophysics Data System (ADS)

Verhaegen, Staf; Nackaerts, Axel; Dusa, Mircea; Carpaij, Rene; Vandenberghe, Geert; Finders, Jo

2006-03-01

The purpose of this paper is to use measurements on real working devices to derive more information than typically measured by the classic line-width measurement techniques. The first part of the paper will discuss the principle of the measurements with a ring oscillator, a circuit used to measure the speed of elementary logic gates. These measurements contribute to the understanding of the exact timing dependencies in circuits, which is of utmost importance for the design and simulation of these circuits. When connecting an odd number of digital inverting stages in a ring, the circuit has no stable digital state but acts as an analog oscillator with the oscillation frequency dependent on the analog propagation delay of the signals through the stages. By varying some conditions during a litho step, the delay change caused by the process condition change can be measured very accurately. The response of the ring oscillator delay to exposure dose is measured and presented in this paper together with a comparison of measured line-width values of the poly gate lines. The second part of the paper will focus on improving the intra-wafer variation of the stage delay. A number of ring oscillators are put in a design at different slit and scan locations. 200mm wafers are processed with 48 full dies present. From the intra-wafer delay fingerprint and the dose sensitivity of the delay an intra-wafer dose correction, also called a dose recipe, is calculated. This dose recipe is used on the scanner to compensate for effects that are the root cause for the delay profile; including reticle and processing such as track, etch and annealing.

Advanced Transport Delay Compensation Algorithms: Results of Delay Measurement and Piloted Performance Tests

NASA Technical Reports Server (NTRS)

Guo, Liwen; Cardullo, Frank M.; Kelly, Lon C.

2007-01-01

This report summarizes the results of delay measurement and piloted performance tests that were conducted to assess the effectiveness of the adaptive compensator and the state space compensator for alleviating the phase distortion of transport delay in the visual system in the VMS at the NASA Langley Research Center. Piloted simulation tests were conducted to assess the effectiveness of two novel compensators in comparison to the McFarland predictor and the baseline system with no compensation. Thirteen pilots with heterogeneous flight experience executed straight-in and offset approaches, at various delay configurations, on a flight simulator where different predictors were applied to compensate for transport delay. The glideslope and touchdown errors, power spectral density of the pilot control inputs, NASA Task Load Index, and Cooper-Harper rating of the handling qualities were employed for the analyses. The overall analyses show that the adaptive predictor results in slightly poorer compensation for short added delay (up to 48 ms) and better compensation for long added delay (up to 192 ms) than the McFarland compensator. The analyses also show that the state space predictor is fairly superior for short delay and significantly superior for long delay than the McFarland compensator.

Rolled-up transmission line structure for a radiofrequency integrated circuit (RFIC)

DOEpatents

Li, Xiuling; Huang, Wen

2015-04-28

A rolled-up transmission line structure for a radiofrequency integrated circuit (RFIC) comprises a multilayer sheet in a rolled configuration comprising multiple turns about a longitudinal axis, where the multilayer sheet comprises a conductive pattern layer on a strain-relieved layer. The conductive pattern layer comprises a first conductive film and a second conductive film separated from the first conductive film in a rolling direction. In the rolled configuration, the first conductive film surrounds the longitudinal axis, and the second conductive film surrounds the first conductive film. The first conductive film serves as a signal line and the second conductive film serves as a conductive shield for the rolled-up transmission line structure.

Global cluster synchronization in nonlinearly coupled community networks with heterogeneous coupling delays.

PubMed

Tseng, Jui-Pin

2017-02-01

This investigation establishes the global cluster synchronization of complex networks with a community structure based on an iterative approach. The units comprising the network are described by differential equations, and can be non-autonomous and involve time delays. In addition, units in the different communities can be governed by different equations. The coupling configuration of the network is rather general. The coupling terms can be non-diffusive, nonlinear, asymmetric, and with heterogeneous coupling delays. Based on this approach, both delay-dependent and delay-independent criteria for global cluster synchronization are derived. We implement the present approach for a nonlinearly coupled neural network with heterogeneous coupling delays. Two numerical examples are given to show that neural networks can behave in a variety of new collective ways under the synchronization criteria. These examples also demonstrate that neural networks remain synchronized in spite of coupling delays between neurons across different communities; however, they may lose synchrony if the coupling delays between the neurons within the same community are too large, such that the synchronization criteria are violated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multiple Velocity Profile Measurements in Hypersonic Flows using Sequentially-Imaged Fluorescence Tagging

NASA Technical Reports Server (NTRS)

Bathel, Brett F.; Danehy, Paul M.; Inmian, Jennifer A.; Jones, Stephen B.; Ivey, Christopher B.; Goyne, Christopher P.

2010-01-01

Nitric-oxide planar laser-induced fluorescence (NO PLIF) was used to perform velocity measurements in hypersonic flows by generating multiple tagged lines which fluoresce as they convect downstream. For each laser pulse, a single interline, progressive scan intensified CCD camera was used to obtain separate images of the initial undelayed and delayed NO molecules that had been tagged by the laser. The CCD configuration allowed for sub-microsecond acquisition of both images, resulting in sub-microsecond temporal resolution as well as sub-mm spatial resolution (0.5-mm x 0.7-mm). Determination of axial velocity was made by application of a cross-correlation analysis of the horizontal shift of individual tagged lines. Quantification of systematic errors, the contribution of gating/exposure duration errors, and influence of collision rate on fluorescence to temporal uncertainty were made. Quantification of the spatial uncertainty depended upon the analysis technique and signal-to-noise of the acquired profiles. This investigation focused on two hypersonic flow experiments: (1) a reaction control system (RCS) jet on an Orion Crew Exploration Vehicle (CEV) wind tunnel model and (2) a 10-degree half-angle wedge containing a 2-mm tall, 4-mm wide cylindrical boundary layer trip. The experiments were performed at the NASA Langley Research Center's 31-inch Mach 10 wind tunnel.

Experiments on Extinction of Fires by Airblast; Flame Displacement as an Extinction Mechanism.

DTIC Science & Technology

1980-05-01

commonly resumed active flaming after delays ranging from minutes to hours.) ~* Therefore, these flow fields are independent of the postive -phase dura- tion...pronounced and apparently very sensitive to location. Even a small perturbation intro- duced into the flow immediately in front of the fire may allow it to...configurations are needed. Acquisition of such data may be delayed , however, until a suitable thermal radiation source can be provided for use with the

Testing Delays Resulting in Increased Identification Accuracy in Line-Ups and Show-Ups.

ERIC Educational Resources Information Center

Dekle, Dawn J.

1997-01-01

Investigated time delays (immediate, two-three days, one week) between viewing a staged theft and attempting an eyewitness identification. Compared lineups to one-person showups in a laboratory analogue involving 412 subjects. Results show that across all time delays, participants maintained a higher identification accuracy with the showup…

Free-running waveform characterization using a delay-time tunable laser based delay-line-free electro-optic sampling oscilloscope

NASA Astrophysics Data System (ADS)

Lin, Gong-Ru

2002-12-01

We develop a delay-line-free and frequency traceable electro-optic sampling oscilloscope by use of a digital phase-locked loop phase shifter (PLL-PS) controlled delay-time-tunable gain-switched laser diode (GSLD). The home-made voltage-controllable PLL-PS exhibits a linear transfer function with ultra-wide phase shifting range of ±350° and tuning error of <±5%, which benefits the advantages of frequency tracking to free-running signals with suppressed timing-jitter. The maximum delay-time of PLL-PS controlled GSLD is up to 1.95 periods by changing the controlling voltage ( VREF) from -3.5 to 3.5 V, which corresponds to 3.9 ns at repetition frequency of 500 MHz. The tuning responsivity and resolution are about 0.56 ns/V and 0.15˜0.2 ps, respectively. The maximum delay-time switching bandwidth of 100 Hz is determined under the control of a saw-tooth modulated VREF function. The waveform sampling of microwave PECL signals generated from a free-running digital frequency divider is performed with acceptable measuring deviation.

The effect of porcelain firing and type of finish line on the marginal fit of zirconia copings.

PubMed

Vojdani, Mahroo; Safari, Anahita; Mohaghegh, Mina; Pardis, Soheil; Mahdavi, Farideh

2015-06-01

Although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. The purpose of this study was to evaluate the marginal fit of zirconia CAD/CAM ceramic crowns before and after porcelain firing. The influence of finish line configuration on the marginal fit was also evaluated. Twenty standardized zirconia CAD/CAM copings were fabricated for chamfer and shoulder finish line designs (n=10). The marginal fit of specimens was measured on 18 points, marked on the master metal die by using a digital microscope. After the crowns were finalized by porcelain veneering, the measurements of marginal fit were performed again. The means and standard deviations were calculated and data were analyzed using student's t-test and paired t-test (α=0.05). There were significant differences between marginal fit of chamfer and shoulder finish line groups before and after porcelain firing (p= 0.014 and p= 0.000, respectively). The marginal gap of copings with shoulder finish line was significantly smaller than those with chamfer configuration (p= 0.000), but there were no significant differences between the two marginal designs, after porcelain firing (p= 0.341). Porcelain veneering was found to have a statistically significant influence on the marginal fit of zirconia CAD/CAM crowns. Both margin configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.

Design of materials configurations for enhanced phononic and electronic properties

NASA Astrophysics Data System (ADS)

Daraio, Chiara

The discovery of novel nonlinear dynamic and electronic phenomena is presented for the specific cases of granular materials and carbon nanotubes. This research was conducted for designing and constructing optimized macro-, micro- and nano-scale structural configurations of materials, and for studying their phononic and electronic behavior. Variation of composite arrangements of granular elements with different elastic properties in a linear chain-of-sphere, Y-junction or 3-D configurations led to a variety of novel phononic phenomena and interesting physical properties, which can be potentially useful for security, communications, mechanical and biomedical engineering applications. Mechanical and electronic properties of carbon nanotubes with different atomic arrangements and microstructures were also investigated. Electronic properties of Y-junction configured carbon nanotubes exhibit an exciting transistor switch behavior which is not seen in linear configuration nanotubes. Strongly nonlinear materials were designed and fabricated using novel and innovative concepts. Due to their unique strongly nonlinear and anisotropic nature, novel wave phenomena have been discovered. Specifically, violations of Snell's law were detected and a new mechanism of wave interaction with interfaces between NTPCs (Nonlinear Tunable Phononic Crystals) was established. Polymer-based systems were tested for the first time, and the tunability of the solitary waves speed was demonstrated. New materials with transformed signal propagation speed in the manageable range of 10-100 m/s and signal amplitude typical for audible speech have been developed. The enhancing of the mitigation of solitary and shock waves in 1-D chains were demonstrated and a new protective medium was designed for practical applications. 1-D, 2-D and 3-D strongly nonlinear system have been investigated providing a broad impact on the whole area of strongly nonlinear wave dynamics and creating experimental basis for new theories and models. Potential applications include (1) designing of a sound scrambler/decoder for secure voice communications, (2) improving invisibility of submarine to acoustic detection signal, (3) noise and shock wave mitigation for protection of vibration sensitive devices such as head mounted vision devices, (4) drastic compression of acoustic signals into centimeter regime impulses for artificial ear implants, hearing aid and devices for ease of conversion to electronic signals and processing, and acoustic delay lines for communication applications.

Jet outflow and open field line measurements on the C-2U advanced beam-driven field-reversed configuration plasma experiment.

PubMed

Sheftman, D; Gupta, D; Roche, T; Thompson, M C; Giammanco, F; Conti, F; Marsili, P; Moreno, C D

2016-11-01

Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations.

Jet outflow and open field line measurements on the C-2U advanced beam-driven field-reversed configuration plasma experiment

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

Sheftman, D., E-mail: dsheftman@trialphaenergy.com; Gupta, D.; Roche, T.

Knowledge and control of the axial outflow of plasma particles and energy along open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven field-reversed configuration plasma. An overview of the diagnostic methods used to perform measurements on the open field line plasma on C-2U is presented, including passive Doppler impurity spectroscopy, microwave interferometry, and triple Langmuir probe measurements. Results of these measurements provide the jet ion temperature and axial velocity, electron density, and high frequency density fluctuations.

High Temperature Superconductivity Applications for Electronic Warfare and Microwave Systems

DTIC Science & Technology

1990-05-01

instantaneous frequency measurement (IFM), as well as, switched delay lines for EW radar range deception and low loss, high resolution MMIC phase...Junction (JJ). This device has been demonstrated in LTSC and is used in very stable ( low noise ), frequency selective, oscillators and very low noise ...following HTSC components: 1) MMIC Filters 2) MMIC Delay Lines/Phase Shifters 3) Microwave Resonators 4) Antenna Feed Networks 5) Low Frequency Antennas 1

1st Order Modeling of a SAW Delay Line using MathCAD(Registered)

NASA Technical Reports Server (NTRS)

Wilson, William C.; Atkinson, Gary M.

2007-01-01

To aid in the development of SAW sensors for Integrated Vehicle Health Monitoring applications, a first order model of a SAW Delay line has been created using MathCadA. The model implements the Impulse Response method to calculate the frequency response, impedance, and insertion loss. This paper presents the model and the results from the model for a SAW delay line design. Integrated Vehicle Health Monitoring (IVHM) of aerospace vehicles requires rugged sensors having reduced volume, mass, and power that can be used to measure a variety of phenomena. Wireless systems are preferred when retro-fitting sensors onto existing vehicles [1]. Surface Acoustic Wave (SAW) devices are capable of sensing: temperature, pressure, strain, chemical species, mass loading, acceleration, and shear stress. SAW technology is low cost, rugged, lightweight, and extremely low power. Passive wireless sensors have been developed using SAW technology. For these reasons new SAW sensors are being investigated for aerospace applications.

Constrained off-line synthesis approach of model predictive control for networked control systems with network-induced delays.

PubMed

Tang, Xiaoming; Qu, Hongchun; Wang, Ping; Zhao, Meng

2015-03-01

This paper investigates the off-line synthesis approach of model predictive control (MPC) for a class of networked control systems (NCSs) with network-induced delays. A new augmented model which can be readily applied to time-varying control law, is proposed to describe the NCS where bounded deterministic network-induced delays may occur in both sensor to controller (S-A) and controller to actuator (C-A) links. Based on this augmented model, a sufficient condition of the closed-loop stability is derived by applying the Lyapunov method. The off-line synthesis approach of model predictive control is addressed using the stability results of the system, which explicitly considers the satisfaction of input and state constraints. Numerical example is given to illustrate the effectiveness of the proposed method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Zero-lag synchronization in coupled time-delayed piecewise linear electronic circuits

NASA Astrophysics Data System (ADS)

Suresh, R.; Srinivasan, K.; Senthilkumar, D. V.; Raja Mohamed, I.; Murali, K.; Lakshmanan, M.; Kurths, J.

2013-07-01

We investigate and report an experimental confirmation of zero-lag synchronization (ZLS) in a system of three coupled time-delayed piecewise linear electronic circuits via dynamical relaying with different coupling configurations, namely mutual and subsystem coupling configurations. We have observed that when there is a feedback between the central unit (relay unit) and at least one of the outer units, ZLS occurs in the two outer units whereas the central and outer units exhibit inverse phase synchronization (IPS). We find that in the case of mutual coupling configuration ZLS occurs both in periodic and hyperchaotic regimes, while in the subsystem coupling configuration it occurs only in the hyperchaotic regime. Snapshots of the time evolution of outer circuits as observed from the oscilloscope confirm the occurrence of ZLS experimentally. The quality of ZLS is numerically verified by correlation coefficient and similarity function measures. Further, the transition to ZLS is verified from the changes in the largest Lyapunov exponents and the correlation coefficient as a function of the coupling strength. IPS is experimentally confirmed using time series plots and also can be visualized using the concept of localized sets which are also corroborated by numerical simulations. In addition, we have calculated the correlation of probability of recurrence to quantify the phase coherence. We have also analytically derived a sufficient condition for the stability of ZLS using the Krasovskii-Lyapunov theory.

Modular support blocks for fluid lines

NASA Technical Reports Server (NTRS)

Dimino, J. M.; Deskin, R. D.

1974-01-01

Modular line block comprises matched modular elements machined to accept fluid lines of different diameters. Modules can support different fluid-line configurations. Top and bottom surfaces are machined to accept dovetail strip used for holding modules together. End modules have holes drilled through to accept fastening screws.

In-line quincke tube muffler

NASA Astrophysics Data System (ADS)

Patrick, William P.; Bryant, Rebecca S.; Greenwald, Larry E.

2002-05-01

A unique low-pressure-drop muffler is described which has been designed to attenuate low frequency tonal noise in ducts. Flow through the muffler is divided into two noncommunicating paths in the cylindrical configuration which was designed, built, and tested. Half of the flow is ducted through a straight central annulus and the other half is ducted through a partitioned outer annulus which directs the flow in a spiral flow pattern around the inner annulus. Thus the outer flow has a longer path length and the sound within the outer annulus is phase-delayed relative to the inner flow causing destructive interference between the inner and outer waves with resulting strong attenuation at the tuned frequencies. A procedure will be described for designing a muffler (with flow) to produce high attenuation at the fundamental noise tone and all harmonics (up to the first cross mode). Results will be presented which show that the muffler achieved over 20 dB attenuation for the first five harmonics of the incident noise in a flowing duct.

Grating-patterned FeCo coated surface acoustic wave device for sensing magnetic field

NASA Astrophysics Data System (ADS)

Wang, Wen; Jia, Yana; Xue, Xufeng; Liang, Yong; Du, Zhaofu

2018-01-01

This study addresses the theoretical and experimental investigations of grating-patterned magnetostrictive FeCo coated surface acoustic wave (SAW) device for sensing magnetic field. The proposed sensor is composed of a configuration of differential dual-delay-line oscillators, and a magnetostrictive FeCo grating array deposited along the SAW propagation path of the sensing device, which suppresses effectively the hysteresis effect by releasing the internal binding force in FeCo. The magnetostrictive strain and ΔE effect from the FeCo coating modulates the SAW propagation characteristic, and the corresponding shift in differential oscillation frequency was utilized to evaluate the measurant. A theoretical model is performed to investigate the wave propagation in layered structure of FeCo/LiNbO3 in the effect of magnetostrictive, and allowing determining the optimal structure. The experimental results indicate that higher sensitivity, excellent linearity, and lower hysteresis error over the typical FeCo thin-film coated sensor were achieved from the grating-patterned FeCo coated sensor successfully.

Volume server: A scalable high speed and high capacity magnetic tape archive architecture with concurrent multi-host access

NASA Technical Reports Server (NTRS)

Rybczynski, Fred

1993-01-01

A major challenge facing data processing centers today is data management. This includes the storage of large volumes of data and access to it. Current media storage for large data volumes is typically off line and frequently off site in warehouses. Access to data archived in this fashion can be subject to long delays, errors in media selection and retrieval, and even loss of data through misplacement or damage to the media. Similarly, designers responsible for architecting systems capable of continuous high-speed recording of large volumes of digital data are faced with the challenge of identifying technologies and configurations that meet their requirements. Past approaches have tended to evaluate the combination of the fastest tape recorders with the highest capacity tape media and then to compromise technology selection as a consequence of cost. This paper discusses an architecture that addresses both of these challenges and proposes a cost effective solution based on robots, high speed helical scan tape drives, and large-capacity media.

Optical alignment of the VLTI

NASA Astrophysics Data System (ADS)

Guisard, Stephane

2003-02-01

When completed the VLTI project will be composed by four 8.2 m Unit Telescopes (UT) and four 1.8 m Auxiliay Telescopes (AT) with their respective Coude trains and relay optics, two test siderostats, 6 (up to 8) Delay lines and 8 Beam compressors with their corresponding feeding mirrors. There will be more than 200 optical components, mirrors and lenses, with diameters ranging from 5 mm to 8200 mm. Their surface shapes range from flat to off-axis ellipsoid, including also spherical, on and off-axis hyperbolae and parabolas as well as cylindrical surfaces. Depending on the interferometer configuration, the different possible optical path lengths are of the order of 100 to 300 meters. We describe briefly the principles chosen as well as the types of criteria and method used for the alignment. The method can certainly be applied to other optical systems. The explanations given are understandable to the non-optician, this text is not intended to be an alignment procedure.

Radiation hard programmable delay line for LHCb calorimeter upgrade

NASA Astrophysics Data System (ADS)

Mauricio, J.; Gascón, D.; Vilasís, X.; Picatoste, E.; Machefert, F.; Lefrancois, J.; Duarte, O.; Beigbeder, C.

2014-01-01

This paper describes the implementation of a SPI-programmable clock delay chip based on a Delay Locked Loop (DLL) in order to shift the phase of the LHC clock (25 ns) in steps of 1ns, with less than 5 ps jitter and 23 ps of DNL. The delay lines will be integrated into ICECAL, the LHCb calorimeter front-end analog signal processing ASIC in the near future. The stringent noise requirements on the ASIC imply minimizing the noise contribution of digital components. This is accomplished by implementing the DLL in differential mode. To achieve the required radiation tolerance several techniques are applied: double guard rings between PMOS and NMOS transistors as well as glitch suppressors and TMR Registers. This 5.7 mm2 chip has been implemented in CMOS 0.35 μm technology.

A 3.9 ps Time-Interval RMS Precision Time-to-Digital Converter Using a Dual-Sampling Method in an UltraScale FPGA

NASA Astrophysics Data System (ADS)

Wang, Yonggang; Liu, Chong

2016-10-01

Field programmable gate arrays (FPGAs) manufactured with more advanced processing technology have faster carry chains and smaller delay elements, which are favorable for the design of tapped delay line (TDL)-style time-to-digital converters (TDCs) in FPGA. However, new challenges are posed in using them to implement TDCs with a high time precision. In this paper, we propose a bin realignment method and a dual-sampling method for TDC implementation in a Xilinx UltraScale FPGA. The former realigns the disordered time delay taps so that the TDC precision can approach the limit of its delay granularity, while the latter doubles the number of taps in the delay line so that the TDC precision beyond the cell delay limitation can be expected. Two TDC channels were implemented in a Kintex UltraScale FPGA, and the effectiveness of the new methods was evaluated. For fixed time intervals in the range from 0 to 440 ns, the average RMS precision measured by the two TDC channels reaches 5.8 ps using the bin realignment, and it further improves to 3.9 ps by using the dual-sampling method. The time precision has a 5.6% variation in the measured temperature range. Every part of the TDC, including dual-sampling, encoding, and on-line calibration, could run at a 500 MHz clock frequency. The system measurement dead time is only 4 ns.

Thorium-based mixed oxide fuel in a pressurized water reactor: A feasibility analysis with MCNP

NASA Astrophysics Data System (ADS)

Tucker, Lucas Powelson

This dissertation investigates techniques for spent fuel monitoring, and assesses the feasibility of using a thorium-based mixed oxide fuel in a conventional pressurized water reactor for plutonium disposition. Both non-paralyzing and paralyzing dead-time calculations were performed for the Portable Spectroscopic Fast Neutron Probe (N-Probe), which can be used for spent fuel interrogation. Also, a Canberra 3He neutron detector's dead-time was estimated using a combination of subcritical assembly measurements and MCNP simulations. Next, a multitude of fission products were identified as candidates for burnup and spent fuel analysis of irradiated mixed oxide fuel. The best isotopes for these applications were identified by investigating half-life, photon energy, fission yield, branching ratios, production modes, thermal neutron absorption cross section and fuel matrix diffusivity. 132I and 97Nb were identified as good candidates for MOX fuel on-line burnup analysis. In the second, and most important, part of this work, the feasibility of utilizing ThMOX fuel in a pressurized water reactor (PWR) was first examined under steady-state, beginning of life conditions. Using a three-dimensional MCNP model of a Westinghouse-type 17x17 PWR, several fuel compositions and configurations of a one-third ThMOX core were compared to a 100% UO2 core. A blanket-type arrangement of 5.5 wt% PuO2 was determined to be the best candidate for further analysis. Next, the safety of the ThMOX configuration was evaluated through three cycles of burnup at several using the following metrics: axial and radial nuclear hot channel factors, moderator and fuel temperature coefficients, delayed neutron fraction, and shutdown margin. Additionally, the performance of the ThMOX configuration was assessed by tracking cycle length, plutonium destroyed, and fission product poison concentration.

Demonstration of a linear optical true-time delay device by use of a microelectromechanical mirror array.

PubMed

Rader, Amber; Anderson, Betty Lise

2003-03-10

We present the design and proof-of-concept demonstration of an optical device capable of producing true-time delay(s) (TTD)(s) for phased array antennas. This TTD device uses a free-space approach consisting of a single microelectromechanical systems (MEMS) mirror array in a multiple reflection spherical mirror configuration based on the White cell. Divergence is avoided by periodic refocusing by the mirrors. By using the MEMS mirror to switch between paths of different lengths, time delays are generated. Six different delays in 1-ns increments were demonstrated by using the Texas Instruments Digital Micromirror Device as the switching element. Losses of 1.6 to 5.2 dB per bounce and crosstalk of -27 dB were also measured, both resulting primarily from diffraction from holes in each pixel and the inter-pixel gaps of the MEMS.

Evaluation of the Affymetrix CytoScan® Dx Assay for Developmental Delay

PubMed Central

Webb, Bryn D.; Scharf, Rebecca J.; Spear, Emily A.; Edelmann, Lisa J.; Stroustrup, Annemarie

2015-01-01

The goal of molecular cytogenetic testing for children presenting with developmental delay is to identify or exclude genetic abnormalities that are associated with cognitive, behavioral, and/or motor symptoms. Until 2010, chromosome analysis was the standard first-line genetic screening test for evaluation of patients with developmental delay when a specific syndrome was not suspected. In 2010, The American College of Medical Genetics and several other groups recommended chromosomal microarray (CMA) as the first-line test in children with developmental delays, multiple congenital anomalies, and/or autism. This test is able to detect regions of genomic imbalances at a much finer resolution than G-banded karyotyping. Until recently, no CMA testing had been approved by the United States Food and Drug Administration (FDA). This review will focus on the use of the Affymetrix CytoScan® Dx Assay, the first CMA to receive FDA approval for the genetic evaluation of individuals with developmental delay. PMID:25350348

A dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled with a waveguide system

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

Wang, Boyun; Wang, Tao, E-mail: wangtao@hust.edu.cn; Tang, Jian

2014-10-07

We theoretically propose a dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled to a waveguide system through external optical pump beams. The optical Kerr effect modulation method is applied to improve tuning rate with response time of subpicoseconds or even femtoseconds. The group delay of an all-optical analog to electromagnetically induced transparency effect can be controlled by tuning either the frequency of photonic crystal microcavities or the propagation phase of line waveguide. Group delay is controlled between 5.88 and 70.98 ps by dynamically tuning resonant frequencies of the microcavities. Alternatively, the group delay is controlled between 1.86more » and 12.08 ps by dynamically tuning the propagation phase of line waveguide. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Results show a new direction toward microstructure integration optical pulse trapping and all-optical dynamical storage of light devices in optical communication and quantum information processing.« less

Characterization of Lifshitz transitions in topological nodal line semimetals

NASA Astrophysics Data System (ADS)

Jiang, Hui; Li, Linhu; Gong, Jiangbin; Chen, Shu

2018-04-01

We introduce a two-band model of three-dimensional nodal line semimetals (NLSMs), the Fermi surface of which at half-filling may form various one-dimensional configurations of different topology. We study the symmetries and "drumhead" surface states of the model, and find that the transitions between different configurations, namely, the Lifshitz transitions, can be identified solely by the number of gap-closing points on some high-symmetry planes in the Brillouin zone. A global phase diagram of this model is also obtained accordingly. We then investigate the effect of some extra terms analogous to a two-dimensional Rashba-type spin-orbit coupling. The introduced extra terms open a gap for the NLSMs and can be useful in engineering different topological insulating phases. We demonstrate that the behavior of surface Dirac cones in the resulting insulating system has a clear correspondence with the different configurations of the original nodal lines in the absence of the gap terms.

Self-Configuration and Self-Optimization Process in Heterogeneous Wireless Networks

PubMed Central

Guardalben, Lucas; Villalba, Luis Javier García; Buiati, Fábio; Sobral, João Bosco Mangueira; Camponogara, Eduardo

2011-01-01

Self-organization in Wireless Mesh Networks (WMN) is an emergent research area, which is becoming important due to the increasing number of nodes in a network. Consequently, the manual configuration of nodes is either impossible or highly costly. So it is desirable for the nodes to be able to configure themselves. In this paper, we propose an alternative architecture for self-organization of WMN based on Optimized Link State Routing Protocol (OLSR) and the ad hoc on demand distance vector (AODV) routing protocols as well as using the technology of software agents. We argue that the proposed self-optimization and self-configuration modules increase the throughput of network, reduces delay transmission and network load, decreases the traffic of HELLO messages according to network’s scalability. By simulation analysis, we conclude that the self-optimization and self-configuration mechanisms can significantly improve the performance of OLSR and AODV protocols in comparison to the baseline protocols analyzed. PMID:22346584

Self-configuration and self-optimization process in heterogeneous wireless networks.

PubMed

Guardalben, Lucas; Villalba, Luis Javier García; Buiati, Fábio; Sobral, João Bosco Mangueira; Camponogara, Eduardo

2011-01-01

Self-organization in Wireless Mesh Networks (WMN) is an emergent research area, which is becoming important due to the increasing number of nodes in a network. Consequently, the manual configuration of nodes is either impossible or highly costly. So it is desirable for the nodes to be able to configure themselves. In this paper, we propose an alternative architecture for self-organization of WMN based on Optimized Link State Routing Protocol (OLSR) and the ad hoc on demand distance vector (AODV) routing protocols as well as using the technology of software agents. We argue that the proposed self-optimization and self-configuration modules increase the throughput of network, reduces delay transmission and network load, decreases the traffic of HELLO messages according to network's scalability. By simulation analysis, we conclude that the self-optimization and self-configuration mechanisms can significantly improve the performance of OLSR and AODV protocols in comparison to the baseline protocols analyzed.

Laser gain on 3p-3d and 3s-3p transitions and X-ray line ratios for the nitrogen isoelectronic sequence

NASA Technical Reports Server (NTRS)

Feldman, U.; Seely, J. F.; Bhatia, A. K.

1989-01-01

Results are presented on calculations of the 72 levels belonging to the 2s(2)2p(3), 2s2p(4), 2p(5), 2s(2)2p(2)3s, 2s(2)2p(2)3p, and 2s(2)2p(2)3d configurations of the N I isoelectronic sequence for the ions Ar XII, Ti XVI, Fe XX, Zn XXIV, and Kr XXX, for electron densities up to 10 to the 24th/cu cm. It was found that large population inversions and gain occur between levels in the 2s(2)2p(2)3p configuration and levels in the 2s(2)2p(2)3d configuration that cannot decay to the ground configuration by an electric dipole transition. For increasing electron densities, the intensities of the X-ray transitions from the 2s(2)2p(2)3p configuration to the ground configuration decrease relative to the transitions from the 2s(2)2p(2)3s and 2s(2)2p(2)3d configurations to the ground configuration. The density dependence of these X-ray line ratios is presented.

Cruise Report for G1-03-GM, USGS Gas Hydrates Cruise, R/V Gyre, 1-14 May 2003, Northern Gulf of Mexico

USGS Publications Warehouse

Hutchinson, Deborah R.; Hart, Patrick E.

2004-01-01

This report gives a summary of the field program and instrumentation used on the R/V Gyre in the Gulf of Mexico in May, 2003, to collect multichannel seismic data in support of USGS and Department of Energy gas hydrate studies. Tabulated statistics, metadata, figures and maps are included to show the breadth of data collected and preliminary interpretations made during the field program. Geophysical data collected during this cruise will be released in a separate report. At the start of the cruise, three test lines were run to compare different source configurations in order to optimize data quality for the objectives of the cruise. The source chosen was the 13/13 in3 Generator-Injector (GI) Gun. Following these tests, a total of 101 lines (approximately 1033 km) of 24-channel high-resolution seismic reflection data were collected in the northern Gulf of Mexico. 59 lines (about 600 km) were collected in and around lease block Keathley Canyon 195. An additional 4 lines (85 km) provided a seismic tie between the Keathley Canyon data and USGS multichannel data collected in 1999. About 253 km of data were collected along 35 short lines in and around lease block Atwater Valley 14 on the floor of the Mississippi Canyon. Three lines (53 km) completed the cruise and provided a seismic tie to USGS multichannel data collected in 1998. Two on-board trained marine-mammal observers fulfilled the requirements determined by NOAA/National Marine Fisheries Service to avoid incidental harassment of marine mammals as established in the Marine Mammal Protection Act (MMPA). A total of three species of dolphins were observed during the cruise and one basking shark. No sperm whales were sighted. During the cruise, seismic operations were not delayed or terminated because of marine mammal activity.

Longitudinal Stability and Control Characteristics from a Flight Investigation of a Cruciform Canard Missile Configuration Having an Exposed Wing-canard Area Ratio of 16:1

NASA Technical Reports Server (NTRS)

Moul, Martin T; Wineman, Andrew R

1952-01-01

A flight investigation has been made to determine the longitudinal stability and control characteristics of a 60 0 delta-wing-canard missile configuration with an exposed wing-canard area ratio of 16:1. The results presented include the longitudinal stability derivatives, control effectiveness, and drag characteristics for a Mach number range of 0.75 to 1.80 and are compared with the results of a similar configuration having larger 6ontrols. Stability characteristics are also presented from the flights of an interdigitated canard configuration at a Mach number of 2.08 and a wing-body configuration at Mach numbers of 1.25 to 1.45. The stability derivatives varied gradually with Mach number with the exception of the damping-in-pitch derivative. Aerodynamic damping in pitch decreased to a minimum at a Mach number of 1.0 3, then increased to a peak value at a Mach number of 1.26 followed by a gradual decrease at higher Mach numbers. The aerodynamic-center location of the in-line canard configuration shifted rearward 13 percent of the mean aerodynamic chord at transonic speeds. The pitching-moment curve slope was 25 percent greater for the model having no canards than for the in-line configuration. No large effects of interdigitation were noted in the stability derivatives. Pitching effectiveness of the in-line configuration was maintained throughout the Mach number range. A comparison of the stability and control characteristics of two canard configurations having different area controls showed that decreasing the control area 44 percent decreased the pitching effectiveness proportionally, shifted the aerodynamic-center location rearward 9 to 14 percent of the mean aerodynamic chord, and reduced the total hinge moments required for 10 trimmed flight about 50 percent at transonic speeds.

Initial Characterization of Optical Communications with Disruption-Tolerant Network Protocols

NASA Technical Reports Server (NTRS)

Schoolcraft, Joshua; Wilson, Keith

2011-01-01

Disruption-tolerant networks (DTNs) are groups of network assets connected with a suite of communication protocol technologies designed to mitigate the effects of link delay and disruption. Application of DTN protocols to diverse groups of network resources in multiple sub-networks results in an overlay network-of-networks with autonomous data routing capability. In space environments where delay or disruption is expected, performance of this type of architecture (such as an interplanetary internet) can increase with the inclusion of new communications mediums and techniques. Space-based optical communication links are therefore an excellent building block of space DTN architectures. When compared to traditional radio frequency (RF) communications, optical systems can provide extremely power-efficient and high bandwidth links bridging sub-networks. Because optical links are more susceptible to link disruption and experience the same light-speed delays as RF, optical-enabled DTN architectures can lessen potential drawbacks and maintain the benefits of autonomous optical communications over deep space distances. These environment-driven expectations - link delay and interruption, along with asymmetric data rates - are the purpose of the proof-of-concept experiment outlined herein. In recognizing the potential of these two technologies, we report an initial experiment and characterization of the performance of a DTN-enabled space optical link. The experiment design employs a point-to-point free-space optical link configured to have asymmetric bandwidth. This link connects two networked systems running a DTN protocol implementation designed and written at JPL for use on spacecraft, and further configured for higher bandwidth performance. Comparing baseline data transmission metrics with and without periodic optical link interruptions, the experiment confirmed the DTN protocols' ability to handle real-world unexpected link outages while maintaining capability of reliably delivering data at relatively high rates. Finally, performance characterizations from this data suggest performance optimizations to configuration and protocols for future optical-specific DTN space link scenarios.

Multi-purpose wind tunnel reaction control model block

NASA Technical Reports Server (NTRS)

Dresser, H. S.; Daileda, J. J. (Inventor)

1978-01-01

A reaction control system nozzle block is provided for testing the response characteristics of space vehicles to a variety of reaction control thruster configurations. A pressurized air system is connected with the supply lines which lead to the individual jet nozzles. Each supply line terminates in a compact cylindrical plenum volume, axially perpendicular and adjacent to the throat of the jet nozzle. The volume of the cylindrical plenum is sized to provide uniform thrust characteristics from each jet nozzle irrespective of the angle of approach of the supply line to the plenum. Each supply line may be plugged or capped to stop the air supply to selected jet nozzles, thereby enabling a variety of nozzle configurations to be obtained from a single model nozzle block.

Analysis of Photonic Phase-Shifting Technique Employing Amplitude-Controlled Fiber-Optic Delay Lines

DTIC Science & Technology

2012-01-13

Controlled Fiber-Optic Delay Lines January 13, 2012 Approved for public release; distribution is unlimited. Meredith N. draa ViNceNt J. Urick keith J...Draa, Vincent J. Urick , and Keith J. Williams Naval Research Laboratory, Code 5652 4555 Overlook Avenue, SW Washington, DC 20375-5320 NRL/MR/5650--12...9376 Approved for public release; distribution is unlimited. Unclassified Unclassified Unclassified UU 29 Vincent J. Urick (202) 767-9352 Fiber optics

Development of wireless, chipless neural stimulator by using one-port surface acoustic wave delay line and diode-capacitor interface

NASA Astrophysics Data System (ADS)

Kim, Jisung; Kim, Saehan; Lee, Keekeun

2017-06-01

For the first time, a wireless and chipless neuron stimulator was developed by utilizing a surface acoustic wave (SAW) delay line, a diode-capacitor interface, a sharp metal tip, and antennas for the stimulation of neurons in the brain. The SAW delay line supersedes presently existing complex wireless transmission systems composed of a few thousands of transistors, enabling the fabrication of wireless and chipless transceiver systems. The diode-capacitor interface was used to convert AC signals to DC signals and induce stimulus pulses at a sharp metal probe. A 400 MHz RF energy was wirelessly radiated from antennas and then stimulation pulses were observed at a sharp gold probe. A ˜5 m reading distance was obtained using a 1 mW power from a network analyzer. The cycles of electromagnetic (EM) radiation from an antenna were controlled by shielding the antenna with an EM absorber. Stimulation pulses with different amplitudes and durations were successfully observed at the probe. The obtained pulses were ˜0.08 mV in amplitude and 3-10 Hz in frequency. Coupling-of-mode (COM) and SPICE modeling simulations were also used to determine the optimal structural parameters for SAW delay line and the values of passive elements. On the basis of the extracted parameters, the entire system was experimentally implemented and characterized.

Multiplexed two in-line holographic recordings for flow characterization in a flexible vessel

NASA Astrophysics Data System (ADS)

Lobera, Julia; Palero, Virginia; Roche, Eva M.; Gómez Climente, Marina; López Torres, Ana M.; Andrés, Nieves; Arroyo, M. Pilar

2017-06-01

The simultaneous presence of the real and virtual images in the hologram reconstruction is inherent in the in-line holography. This drawback can be overcome with a shifted knife-edge aperture at the focal plane of the imaging lens. The shifted aperture DIH produces holograms where the real and virtual images are completely separated. In this paper we propose a modification of the shifted aperture DIH that allows recording two holograms simultaneously using one camera, while retaining the simplicity of the in-line configuration and the advantage of the shifted-aperture strategy. As in typical stereoscopy, the advantage of this configuration is limited by the angle between the two illuminating beams, and therefore the aperture size. Some improvement on the out-of-plane resolution can be expected from a combined analysis of the multiplexed holograms. In order to compare this technique with other in-line holographic configurations, several experiments have been performed to study the spatial resolution along the optical axis. The capabilities of the different techniques for characterizing the flow in a flexible and transparent model of a carotid bifurcation are also investigated.

Evaluating the effects of bilingual traffic signs on driver performance and safety.

PubMed

Jamson, S L; Tate, F N; Jamson, A H

2005-12-15

Variable message signs (VMS) can provide immediate and relevant information to road users and bilingual VMS can provide great flexibility in countries where a significant proportion of the population speak an alternative language to the majority. The study reported here evaluates the effect of various bilingual VMS configurations on driver behaviour and safety. The aim of the study was to determine whether or not the visual distraction associated with bilingual VMS signs of different configurations (length, complexity) impacted on driving performance. A driving simulator was used to allow full control over the scenarios, road environment and sign configuration and both longitudinal and lateral driver performance was assessed. Drivers were able to read one- and two-line monolingual signs and two-line bilingual signs without disruption to their driving behaviour. However, drivers significantly reduced their speed in order to read four-line monolingual and four-line bilingual signs, accompanied by an increase in headway to the vehicle in front. This implies that drivers are possibly reading the irrelevant text on the bilingual sign and various methods for reducing this effect are discussed.

Innovative Design Systems: Where Are We, and Where Do We Go from Here

DTIC Science & Technology

1990-01-12

Description of a Tap U Figure 4- 5 : Causal Explanation of the Tap Function 12 Figre 4- 6 : The configuration space and qualitative 13 states of a tap Figure 4...Cunrniy, syntactic relaxations are most widely used. For example the constraint "Total Delay <- 5 hours" could be changed to: "Total delay <- 6 ...alternatives by way of ideas 5 . Incubation: Letting up, to invite illumination 6 . Synthesis: Putting the pieces together 7. Evaluation: Judging the

Comparison of coherently coupled multi-cavity and quantum dot embedded single cavity systems.

PubMed

Kocaman, Serdar; Sayan, Gönül Turhan

2016-12-12

Temporal group delays originating from the optical analogue to electromagnetically induced transparency (EIT) are compared in two systems. Similar transmission characteristics are observed between a coherently coupled high-Q multi-cavity array and a single quantum dot (QD) embedded cavity in the weak coupling regime. However, theoretically generated group delay values for the multi-cavity case are around two times higher. Both configurations allow direct scalability for chip-scale optical pulse trapping and coupled-cavity quantum electrodynamics (QED).

On the Maximum Mass of Differentially Rotating Neutron Stars

NASA Astrophysics Data System (ADS)

Baumgarte, Thomas W.; Shapiro, Stuart L.; Shibata, Masaru

2000-01-01

We construct relativistic equilibrium models of differentially rotating neutron stars and show that they can support significantly more mass than their nonrotating or uniformly rotating counterparts. We dynamically evolve such ``hypermassive'' models in full general relativity and show that there do exist configurations that are dynamically stable against radial collapse and bar formation. Our results suggest that the remnant of binary neutron star coalescence may be temporarily stabilized by differential rotation, leading to delayed collapse and a delayed gravitational wave burst.

Kinematical line broadening and spatially resolved line profiles from AGN.

NASA Astrophysics Data System (ADS)

Schulz, H.; Muecke, A.; Boer, B.; Dresen, M.; Schmidt-Kaler, T.

1995-03-01

We study geometrical effects for emission-line broadening in the optically thin limit by integrating the projected line emissivity along prespecified lines of sight that intersect rotating or expanding disks or cone-like configurations. Analytical expressions are given for the case that emissivity and velocity follow power laws of the radial distance. The results help to interpret spatially resolved spectra and to check the reliability of numerical computations. In the second part we describe a numerical code applicable to any geometrical configuration. Turbulent motions, atmospheric seeing and effects induced by the size of the observing aperture are simulated with appropriate convolution procedures. An application to narrow-line Hα profiles from the central region of the Seyfert galaxy NGC 7469 is presented. The shapes and asymmetries as well as the relative strengths of the Hα lines from different spatial positions can be explained by emission from a nuclear rotating disk of ionized gas, for which the distribution of Hα line emissivity and the rotation curve are derived. Appreciable turbulent line broadening with a Gaussian σ of ~40% of the rotational velocity has to be included to obtain a satisfactory fit.

NMR logging apparatus

DOEpatents

Walsh, David O; Turner, Peter

2014-05-27

Technologies including NMR logging apparatus and methods are disclosed. Example NMR logging apparatus may include surface instrumentation and one or more downhole probes configured to fit within an earth borehole. The surface instrumentation may comprise a power amplifier, which may be coupled to the downhole probes via one or more transmission lines, and a controller configured to cause the power amplifier to generate a NMR activating pulse or sequence of pulses. Impedance matching means may be configured to match an output impedance of the power amplifier through a transmission line to a load impedance of a downhole probe. Methods may include deploying the various elements of disclosed NMR logging apparatus and using the apparatus to perform NMR measurements.

Measuring a Fiber-Optic Delay Line Using a Mode-Locked Laser

NASA Technical Reports Server (NTRS)

Tu, Meirong; McKee, Michael R.; Pak, Kyung S.; Yu, Nan

2010-01-01

The figure schematically depicts a laboratory setup for determining the optical length of a fiber-optic delay line at a precision greater than that obtainable by use of optical time-domain reflectometry or of mechanical measurement of length during the delay-line-winding process. In this setup, the delay line becomes part of the resonant optical cavity that governs the frequency of oscillation of a mode-locked laser. The length can then be determined from frequency-domain measurements, as described below. The laboratory setup is basically an all-fiber ring laser in which the delay line constitutes part of the ring. Another part of the ring - the laser gain medium - is an erbium-doped fiber amplifier pumped by a diode laser at a wavelength of 980 nm. The loop also includes an optical isolator, two polarization controllers, and a polarizing beam splitter. The optical isolator enforces unidirectional lasing. The polarization beam splitter allows light in only one polarization mode to pass through the ring; light in the orthogonal polarization mode is rejected from the ring and utilized as a diagnostic output, which is fed to an optical spectrum analyzer and a photodetector. The photodetector output is fed to a radio-frequency spectrum analyzer and an oscilloscope. The fiber ring laser can generate continuous-wave radiation in non-mode-locked operation or ultrashort optical pulses in mode-locked operation. The mode-locked operation exhibited by this ring is said to be passive in the sense that no electro-optical modulator or other active optical component is used to achieve it. Passive mode locking is achieved by exploiting optical nonlinearity of passive components in such a manner as to obtain ultra-short optical pulses. In this setup, the particular nonlinear optical property exploited to achieve passive mode locking is nonlinear polarization rotation. This or any ring laser can support oscillation in multiple modes as long as sufficient gain is present to overcome losses in the ring. When mode locking is achieved, oscillation occurs in all the modes having the same phase and same polarization. The frequency interval between modes, often denoted the free spectral range (FSR), is given by c/nL, where c is the speed of light in vacuum, n is the effective index of refraction of the fiber, and L is the total length of optical path around the ring. Therefore, the length of the fiber-optic delay line, as part of the length around the ring, can be calculated from the FSRs measured with and without the delay line incorporated into the ring. For this purpose, the FSR measurements are made by use of the optical and radio-frequency spectrum analyzers. In experimentation on a 10-km-long fiber-optic delay line, it was found that this setup made it possible to measure the length to within a fractional error of about 3 10(exp -6), corresponding to a length error of 3 cm. In contrast, measurements by optical time-domain reflectometry and mechanical measurement were found to be much less precise: For optical time-domain reflectometry, the fractional error was found no less than 10(exp -4) (corresponding to a length error of 1 m) and for mechanical measurement, the fractional error was found to be about 10(exp -2) (corresponding to a length error of 100 m).

Delayed temporal discrimination in pigeons: A comparison of two procedures

PubMed Central

Chatlosh, Diane L.; Wasserman, Edward A.

1987-01-01

A within-subjects comparison was made of pigeons' performance on two temporal discrimination procedures that were signaled by differently colored keylight samples. During stimulus trials, a peck on the key displaying a slanted line was reinforced following short keylight samples, and a peck on the key displaying a horizontal line was reinforced following long keylight samples, regardless of the location of the stimuli on those two choice keys. During position trials, a peck on the left key was reinforced following short keylight samples and a peck on the right key was reinforced following long keylight samples, regardless of which line stimulus appeared on the correct key. Thus, on stimulus trials, the correct choice key could not be discriminated prior to the presentation of the test stimuli, whereas on position trials, the correct choice key could be discriminated during the presentation of the sample stimulus. During Phase 1, with a 0-s delay between sample and choice stimuli, discrimination learning was faster on position trials than on stimulus trials for all 4 birds. During Phase 2, 0-, 0.5-, and 1.0-s delays produced differential loss of stimulus control under the two tasks for 2 birds. Response patterns during the delay intervals provided some evidence for differential mediation of the two delayed discriminations. These between-task differences suggest that the same processes may not mediate performance in each. PMID:16812483

A liquid lens switching-based motionless variable fiber-optic delay line

NASA Astrophysics Data System (ADS)

Khwaja, Tariq Shamim; Reza, Syed Azer; Sheikh, Mumtaz

2018-05-01

We present a Variable Fiber-Optic Delay Line (VFODL) module capable of imparting long variable delays by switching an input optical/RF signal between Single Mode Fiber (SMF) patch cords of different lengths through a pair of Electronically Controlled Tunable Lenses (ECTLs) resulting in a polarization-independent operation. Depending on intended application, the lengths of the SMFs can be chosen accordingly to achieve the desired VFODL operation dynamic range. If so desired, the state of the input signal polarization can be preserved with the use of commercially available polarization-independent ECTLs along with polarization-maintaining SMFs (PM-SMFs), resulting in an output polarization that is identical to the input. An ECTL-based design also improves power consumption and repeatability. The delay switching mechanism is electronically-controlled, involves no bulk moving parts, and can be fully-automated. The VFODL module is compact due to the use of small optical components and SMFs that can be packaged compactly.

A position- and time-sensitive photon-counting detector with delay- line read-out

NASA Astrophysics Data System (ADS)

Jagutzki, Ottmar; Dangendorf, Volker; Lauck, Ronald; Czasch, Achim; Milnes, James

2007-05-01

We have developed image intensifier tubes with delay-anode read-out for time- and position-sensitive photon counting. The timing precision is better than 1 ns with 1000x1000 pixels position resolution and up to one megacounts/s processing rate. Large format detectors of 40 and 75 mm active diameter with internal helical-wire delay-line anodes have been produced and specified. A different type of 40 and 25 mm tubes with semi-conducting screen for image charge read-out allow for an economic and robust tube design and for placing the read-out anodes outside the sealed housing. Two types of external delay-line anodes, i.e. pick-up electrodes for the image charge, have been tested. We present tests of the detector and anode performance. Due to the low background this technique is well suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. As an example we present the application of scintillator read-out in time-of-flight (TOF) neutron radiography. Further applications so far are Fluorescence Life-time Microscopy (FLIM) and Astronomy.

Localized normalization for improved calibration curves of manganese and zinc in laser-induced plasma spectroscopy

NASA Astrophysics Data System (ADS)

Sabri, Nursalwanie Mohd; Haider, Zuhaib; Tufail, Kashif; Imran, Muhammad; Ali, Jalil

2017-03-01

Laser-induced plasma spectroscopy is performed to determine the elemental compositions of manganese and zinc in potassium bromide (KBr) matrix. This work has utilized Q-switched Nd:YAG laser installed in LIBS2500plus system at fundamental wavelength. The pelletized sample were ablated in air with maximum laser energy of 650 mJ for different gate delays ranging from 0-18 µs. The spectra of samples are obtained for five different compositions containing preferred spectral lines. The intensity of spectral line is observed at its maximum at a gate-delay 0.83 µs and subsequently decayed exponentially with the increasing of gate delay. Maximum signal-to-background ratio of Mn and Zn were found at gate delays of 7.92 and 7.50 µs, respectively. Initial calibration curves show bad data fitting, whereas the locally normalized intensity for both spectral lines shows enhancement since it is more linearly regressed. This study will give a better understanding in studying the plasma emission and the spectra analysis. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 24 May 2017.

Influence of the magnetic field configuration on the plasma flow in Hall thrusters

NASA Astrophysics Data System (ADS)

Andreussi, T.; Giannetti, V.; Leporini, A.; Saravia, M. M.; Andrenucci, M.

2018-01-01

In Hall propulsion, the thrust is provided by the acceleration of ions in a plasma generated in a cross-field configuration. Standard thruster configurations have annular channels with an almost radial magnetic field at the channel exit. A potential difference is imposed in the axial direction and the intensity of the magnetic field is calibrated in order to hinder the electron motion, while leaving the ions non-magnetised. Magnetic field lines can be assumed, as a first approximation, as lines of constant electron temperature and of thermalized potential. In typical thruster configurations, the discharge occurs inside a ceramic channel and, due to plasma-wall interactions, the electron temperature is typically low, less than few tens of eV. Hence, the magnetic field lines can be effectively used to tailor the distribution of the electrostatic potential. However, the erosion of the ceramic walls caused by the ion bombardment represents the main limiting factor of the thruster lifetime and new thruster configurations are currently under development. For these configurations, classical first order models of the plasma dynamics fail to grasp the influence of the magnetic topology on the plasma flow. In the present paper, a novel approach to investigate the correlation between magnetic field topology and thruster performance is presented. Due to the anisotropy induced by the magnetic field, the gradients of the plasma properties are assumed to be mainly in the direction orthogonal to the local magnetic field, thus enabling a quasi-one-dimensional description in magnetic coordinates. Theoretical and experimental investigations performed on a 5 kW class Hall thruster with different magnetic field configurations are then presented and discussed.

On the existence of the field line solutions of the Einstein-Maxwell equations

NASA Astrophysics Data System (ADS)

Vancea, Ion V.

The main result of this paper is the proof that there are local electric and magnetic field configurations expressed in terms of field lines on an arbitrary hyperbolic manifold. This electromagnetic field is described by (dual) solutions of the Maxwell’s equations of the Einstein-Maxwell theory. These solutions have the following important properties: (i) they are general, in the sense that the knot solutions are particular cases of them and (ii) they reduce to the electromagnetic fields in the field line representation in the flat space-time. Also, we discuss briefly the real representation of these electromagnetic configurations and write down the corresponding Einstein equations.

The Effect of Porcelain Firing and Type of Finish Line on the Marginal Fit of Zirconia Copings

PubMed Central

Vojdani, Mahroo; Safari, Anahita; Mohaghegh, Mina; Pardis, Soheil; Mahdavi, Farideh

2015-01-01

Statement of the Problem Although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. Purpose The purpose of this study was to evaluate the marginal fit of zirconia CAD/CAM ceramic crowns before and after porcelain firing. The influence of finish line configuration on the marginal fit was also evaluated. Materials and Method Twenty standardized zirconia CAD/CAM copings were fabricated for chamfer and shoulder finish line designs (n=10). The marginal fit of specimens was measured on 18 points, marked on the master metal die by using a digital microscope. After the crowns were finalized by porcelain veneering, the measurements of marginal fit were performed again. The means and standard deviations were calculated and data were analyzed using student’s t-test and paired t-test (α=0.05). Results There were significant differences between marginal fit of chamfer and shoulder finish line groups before and after porcelain firing (p= 0.014 and p= 0.000, respectively). The marginal gap of copings with shoulder finish line was significantly smaller than those with chamfer configuration (p= 0.000), but there were no significant differences between the two marginal designs, after porcelain firing (p= 0.341). Conclusion Porcelain veneering was found to have a statistically significant influence on the marginal fit of zirconia CAD/CAM crowns. Both margin configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy. PMID:26046107

Characteristics of gamma-ray line flares

NASA Technical Reports Server (NTRS)

Bai, T.; Dennis, B.

1983-01-01

Observations of solar gamma rays by the Solar Maximum Mission (SMM) demonstrate that energetic protons and ions are rapidly accelerated during the impulsive phase. To understand the acceleration mechanisms for these particles, the characteristics of the gamma ray line flares observed by SMM were studied. Some very intense hard X-ray flares without detectable gamma ray lines were also investigated. Gamma ray line flares are distinguished from other flares by: (1) intense hard X-ray and microwave emissions; (2) delay of high energy hard X-rays; (3) emission of type 2 and/or type 4 radio bursts; and (4) flat hard X-ray spectra (average power law index: 3.1). The majority of the gamma ray line flares shared all these characteristics, and the remainder shared at least three of them. Positive correlations were found between durations of spike bursts and spatial sizes of flare loops as well as between delay times and durations of spike bursts.

Penning plasma based simultaneous light emission source of visible and VUV lights

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

Vyas, G. L., E-mail: glvyas27@gmail.com; Prakash, R.; Pal, U. N.

In this paper, a laboratory-based penning plasma discharge source is reported which has been developed in two anode configurations and is able to produce visible and VUV lights simultaneously. The developed source has simultaneous diagnostics facility using Langmuir probe and optical emission spectroscopy. The two anode configurations, namely, double ring and rectangular configurations, have been studied and compared for optimum use of the geometry for efficient light emissions and recording. The plasma is produced using helium gas and admixture of three noble gases including helium, neon, and argon. The source is capable to produce eight spectral lines for pure heliummore » in the VUV range from 20 to 60 nm and total 24 spectral lines covering the wavelength range 20–106 nm for the admixture of gases. The large range of VUV lines is generated from gaseous admixture rather from the sputtered materials. The recorded spectrum shows that the plasma light radiations in both visible and VUV range are larger in double ring configuration than that of the rectangular configurations at the same discharge operating conditions. To clearly understand the difference, the imaging of the discharge using ICCD camera and particle-in-cell simulation using VORPAL have also been carried out. The effect of ion diffusion, metastable collision with the anode wall and the nonlinear effects are correlated to explain the results.« less

The pore-lining region of shaker voltage-gated potassium channels: comparison of beta-barrel and alpha-helix bundle models.

PubMed Central

Kerr, I D; Sansom, M S

1997-01-01

Although there is a large body of site-directed mutagenesis data that identify the pore-lining sequence of the voltage-gated potassium channel, the structure of this region remains unknown. We have interpreted the available biochemical data as a set of topological and orientational restraints and employed these restraints to produce molecular models of the potassium channel pore region, H5. The H5 sequence has been modeled either as a tetramer of membrane-spanning beta-hairpins, thus producing an eight-stranded beta-barrel, or as a tetramer of incompletely membrane-spanning alpha-helical hairpins, thus producing an eight-staved alpha-helix bundle. In total, restraints-directed modeling has produced 40 different configurations of the beta-barrel model, each configuration comprising an ensemble of 20 structures, and 24 different configurations of the alpha-helix bundle model, each comprising an ensemble of 24 structures. Thus, over 1300 model structures for H5 have been generated. Configurations have been ranked on the basis of their predicted pore properties and on the extent of their agreement with the biochemical data. This ranking is employed to identify particular configurations of H5 that may be explored further as models of the pore-lining region of the voltage-gated potassium channel pore. Images FIGURE 7 FIGURE 12 PMID:9251779

Endpoint Naming for Space Delay/Disruption Tolerant Networking

NASA Technical Reports Server (NTRS)

Clare, Loren; Burleigh, Scott; Scott, Keith

2010-01-01

Delay/Disruption Tolerant Networking (DTN) provides solutions to space communication challenges such as disconnections when orbiters lose line-of-sight with landers, long propagation delays over interplanetary links, and other operational constraints. DTN is critical to enabling the future space internetworking envisioned by NASA. Interoperability with international partners is essential and standardization is progressing through both the CCSDS and the IETF.

Electronic Combat Hardware-in-the-Loop Testing in an Open Air Environment

DTIC Science & Technology

1994-09-01

APQ- 126 (F-111) Gun Dish Squat Eye ANAWG-9 (F-14) Grill Pan Straight Flush I-Hawk Hawk Screech Sun Visor Head Light Tall King High Fix Team Work High...the required delay to the IF, the SPCs contain a Teledyne Microwave Bulk Acoustic Wave (BAW) delay line as well as a Coherent Variable Delay Unit

High frequency power distribution system

NASA Technical Reports Server (NTRS)

Patel, Mikund R.

1986-01-01

The objective of this project was to provide the technology of high frequency, high power transmission lines to the 100 kW power range at 20 kHz frequency. In addition to the necessary design studies, a 150 m long, 600 V, 60 A transmission line was built, tested and delivered for full vacuum tests. The configuration analysis on five alternative configurations resulted in the final selection of the three parallel Litz straps configuration, which gave a virtually concentric design in the electromagnetic sense. Low inductance, low EMI and flexibility in handling are the key features of this configuration. The final design was made after a parametric study to minimize the losses, weight and inductance. The construction of the cable was completed with no major difficulties. The R,L,C parameters measured on the cable agreed well with the calculated values. The corona tests on insulation samples showed a safety factor of 3.

Elmo bumpy square plasma confinement device

DOEpatents

Owen, L.W.

1985-01-01

The invention is an Elmo bumpy type plasma confinement device having a polygonal configuration of closed magnet field lines for improved plasma confinement. In the preferred embodiment, the device is of a square configuration which is referred to as an Elmo bumpy square (EBS). The EBS is formed by four linear magnetic mirror sections each comprising a plurality of axisymmetric assemblies connected in series and linked by 90/sup 0/ sections of a high magnetic field toroidal solenoid type field generating coils. These coils provide corner confinement with a minimum of radial dispersion of the confined plasma to minimize the detrimental effects of the toroidal curvature of the magnetic field. Each corner is formed by a plurality of circular or elliptical coils aligned about the corner radius to provide maximum continuity in the closing of the magnetic field lines about the square configuration confining the plasma within a vacuum vessel located within the various coils forming the square configuration confinement geometry.

Design of lane merges at rural freeway construction work zones.

DOT National Transportation Integrated Search

2008-02-01

The goal of this project is to evaluate unconventional lane-drop merge configurations in the vicinity of construction work zones on rural freeways to comparatively assess the conditions of the various designs that impact delay, flow, and safety throu...

Infrared coronal emission lines and the possibility of their laser emission in Seyfert nuclei

NASA Technical Reports Server (NTRS)

Greenhouse, Matthew A.; Feldman, Uri; Smith, Howard A.; Klapisch, Marcel; Bhatia, Anand K.; Bar-Shalom, Avi

1993-01-01

Results are presented from detailed balance calculations, and a compilation of atomic data and other model calculations designed to support upcoming ISO and current observing programs involving IR coronal emission lines, together with a table with a complete line list of infrared transitions within the ground configurations 2s2 2p(k), 3s2 3p(k), and the first excited configurations 2s 2p and 3s 3p of highly ionized astrophysically abundant elements. The temperature and density parameter space for dominant cooling via IR coronal lines is presented, and the relationship of IR and optical coronal lines is discussed. It is found that, under physical conditions found in Seyfert nuclei, 14 of 70 transitions examined have significant population inversions in levels that give rise to IR coronal lines. Several IR coronal line transitions were found to have laser gain lengths that correspond to column densities of 10 exp 24-25/sq cm which are modeled to exist in Seyfert nuclei. Observations that can reveal inverted level populations and laser gain in IR coronal lines are suggested.

Line scanning time-of-flight laser sensor for intelligent transport systems, combining wide field-of-view optics of 30 deg, high scanning speed of 0.9 ms/line, and simple sensor configuration

NASA Astrophysics Data System (ADS)

Imaki, Masaharu; Kameyama, Shumpei; Ishimura, Eitaro; Nakaji, Masaharu; Yoshinaga, Hideo; Hirano, Yoshihito

2017-03-01

We developed a line scanning time-of-flight (TOF) laser sensor for an intelligent transport system (ITS), which combines wide field-of-view (FOV) receiving optics of 30 deg and a high-speed microelectro mechanical system scanner of 0.9 ms/line with a simple sensor configuration. The newly developed high-aspect ratio photodiode realizes the scanless and wide FOV receiver. The sinusoidal wave intensity modulation method is used for the TOF measurement. This enables the noise reduction of the trans-impedance amplifier by applying the LC-resonant method. The vehicle detection and axle counting, which are the important functions in ITS, are also demonstrated.

Acoustic radiation from lined, unflanged ducts: Acoustic source distribution program

NASA Technical Reports Server (NTRS)

Beckemeyer, R. J.; Sawdy, D. T.

1971-01-01

An acoustic radiation analysis was developed to predict the far-field characteristics of fan noise radiated from an acoustically lined unflanged duct. This analysis is comprised of three modular digital computer programs which together provide a capability of accounting for the impedance mismatch at the duct exit plane. Admissible duct configurations include circular or annular, with or without an extended centerbody. This variation in duct configurations provides a capability of modeling inlet and fan duct noise radiation. The computer programs are described in detail.

Passive magnetic shielding in MRI-Linac systems.

PubMed

Whelan, Brendan; Kolling, Stefan; Oborn, Brad M; Keall, Paul

2018-03-26

Passive magnetic shielding refers to the use of ferromagnetic materials to redirect magnetic field lines away from vulnerable regions. An application of particular interest to the medical physics community is shielding in MRI systems, especially integrated MRI-linear accelerator (MRI-Linac) systems. In these systems, the goal is not only to minimize the magnetic field in some volume, but also to minimize the impact of the shield on the magnetic fields within the imaging volume of the MRI scanner. In this work, finite element modelling was used to assess the shielding of a side coupled 6 MV linac and resultant heterogeneity induced within the 30 cm diameter of spherical volume (DSV) of a novel 1 Tesla split bore MRI magnet. A number of different shield parameters were investigated; distance between shield and magnet, shield shape, shield thickness, shield length, openings in the shield, number of concentric layers, spacing between each layer, and shield material. Both the in-line and perpendicular MRI-Linac configurations were studied. By modifying the shield shape around the linac from the starting design of an open ended cylinder, the shielding effect was boosted by approximately 70% whilst the impact on the magnet was simultaneously reduced by approximately 10%. Openings in the shield for the RF port and beam exit were substantial sources of field leakage; however it was demonstrated that shielding could be added around these openings to compensate for this leakage. Layering multiple concentric shield shells was highly effective in the perpendicular configuration, but less so for the in-line configuration. Cautious use of high permeability materials such as Mu-metal can greatly increase the shielding performance in some scenarios. In the perpendicular configuration, magnetic shielding was more effective and the impact on the magnet lower compared with the in-line configuration.

Passive magnetic shielding in MRI-Linac systems

NASA Astrophysics Data System (ADS)

Whelan, Brendan; Kolling, Stefan; Oborn, Brad M.; Keall, Paul

2018-04-01

Passive magnetic shielding refers to the use of ferromagnetic materials to redirect magnetic field lines away from vulnerable regions. An application of particular interest to the medical physics community is shielding in MRI systems, especially integrated MRI-linear accelerator (MRI-Linac) systems. In these systems, the goal is not only to minimize the magnetic field in some volume, but also to minimize the impact of the shield on the magnetic fields within the imaging volume of the MRI scanner. In this work, finite element modelling was used to assess the shielding of a side coupled 6 MV linac and resultant heterogeneity induced within the 30 cm diameter of spherical volume (DSV) of a novel 1 Tesla split bore MRI magnet. A number of different shield parameters were investigated; distance between shield and magnet, shield shape, shield thickness, shield length, openings in the shield, number of concentric layers, spacing between each layer, and shield material. Both the in-line and perpendicular MRI-Linac configurations were studied. By modifying the shield shape around the linac from the starting design of an open ended cylinder, the shielding effect was boosted by approximately 70% whilst the impact on the magnet was simultaneously reduced by approximately 10%. Openings in the shield for the RF port and beam exit were substantial sources of field leakage; however it was demonstrated that shielding could be added around these openings to compensate for this leakage. Layering multiple concentric shield shells was highly effective in the perpendicular configuration, but less so for the in-line configuration. Cautious use of high permeability materials such as Mu-metal can greatly increase the shielding performance in some scenarios. In the perpendicular configuration, magnetic shielding was more effective and the impact on the magnet lower compared with the in-line configuration.

Magnonic crystal as a delay line for low-noise auto-oscillators

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

Bankowski, Elena; Meitzler, Thomas; Khymyn, Roman S., E-mail: khiminr@gmail.com

2015-09-21

It is demonstrated that a delay line based on a one-dimensional magnonic crystal used in a feedback loop of a microwave auto-oscillator can substantially reduce the phase noise figure and improve other vital performance characteristics of the auto-oscillator. The advantage is achieved due to the increase of the effective delay time in the magnonic crystal, compared to the case of an un-patterned yttrium iron garnet (YIG) film, and improvement of the power-handling characteristics due to the now possible increase of the YIG film thickness. The internal modes of a magnonic crystal caused by the periodic energy exchange between the incidentmore » and reflected spin waves play the dominant role in the described effect.« less

Elimination of residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy using an optical fiber delay line.

PubMed

Chakraborty, Arup Lal; Ruxton, Keith; Johnstone, Walter; Lengden, Michael; Duffin, Kevin

2009-06-08

A new fiber-optic technique to eliminate residual amplitude modulation in tunable diode laser wavelength modulation spectroscopy is presented. The modulated laser output is split to pass in parallel through the gas measurement cell and an optical fiber delay line, with the modulation frequency / delay chosen to introduce a relative phase shift of pi between them. The two signals are balanced using a variable attenuator and recombined through a fiber coupler. In the absence of gas, the direct laser intensity modulation cancels, thereby eliminating the high background. The presence of gas induces a concentration-dependent imbalance at the coupler's output from which the absolute absorption profile is directly recovered with high accuracy using 1f detection.

S-band SBAW microwave source, phase 2

NASA Technical Reports Server (NTRS)

1983-01-01

Results of aging experiments on 1.072 GHz SBAW oscillators are discussed as well as the design, fabrication and test of 2.143 GHz SBAW delay lines. Two design approaches were implemented. The third harmonic transducer on 36 deg rotated Y cut quartz proved to be the most useful design, whereas the fifth harmonic transducer on - 50 5 deg rotated Y cut quartz suffered from high insertion loss and poor sidelobe rejection. The construction and characterization of the 2 GHz SBAW oscillator are described. Phase noise, frequency dependence on temperature, and 6-month aging were measured. Some SAW and SBAW oscillators were compared as were both the 1 and 2 GHz oscillators. The 2 GHz SBAW oscillator showed significant improvement in phase noise and temperature stability over the 2 GHz SAW oscillator developed in previous NASA programs. A technique to produce SBAW delay lines of different frequencies from a single mask is examined. The delay lines were incorporated into oscillator circuits to demonstrate the ability to select the frequency output of the SBAW oscillator.

Network configuration management : paving the way to network agility.

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

Maestas, Joseph H.

2007-08-01

Sandia networks consist of nearly nine hundred routers and switches and nearly one million lines of command code, and each line ideally contributes to the capabilities of the network to convey information from one location to another. Sandia's Cyber Infrastructure Development and Deployment organizations recognize that it is therefore essential to standardize network configurations and enforce conformance to industry best business practices and documented internal configuration standards to provide a network that is agile, adaptable, and highly available. This is especially important in times of constrained budgets as members of the workforce are called upon to improve efficiency, effectiveness, andmore » customer focus. Best business practices recommend using the standardized configurations in the enforcement process so that when root cause analysis results in recommended configuration changes, subsequent configuration auditing will improve compliance to the standard. Ultimately, this minimizes mean time to repair, maintains the network security posture, improves network availability, and enables efficient transition to new technologies. Network standardization brings improved network agility, which in turn enables enterprise agility, because the network touches all facets of corporate business. Improved network agility improves the business enterprise as a whole.« less

Labeled line drawing of Galileo spacecraft's atmospheric probe

NASA Technical Reports Server (NTRS)

1989-01-01

Labeled line drawing entitled GALILEO PROBE identifies the deceleration module aft cover, descent module, and deceleration module aeroshell configurations and dimensions prior to and during entry into Jupiter's atmosphere.

Labeled line drawing of Galileo spacecraft's atmospheric probe

NASA Image and Video Library

1989-09-11

Labeled line drawing entitled GALILEO PROBE identifies the deceleration module aft cover, descent module, and deceleration module aeroshell configurations and dimensions prior to and during entry into Jupiter's atmosphere.

Implementing the concurrent operation of sub-arrays in the ALMA correlator

NASA Astrophysics Data System (ADS)

Amestica, Rodrigo; Perez, Jesus; Lacasse, Richard; Saez, Alejandro

2016-07-01

The ALMA correlator processes the digitized signals from 64 individual antennas to produce a grand total of 2016 correlated base-lines, with runtime selectable lags resolution and integration time. The on-line software system can process a maximum of 125M visibilities per second, producing an archiving data rate close to one sixteenth of the former (7.8M visibilities per second with a network transfer limit of 60 MB/sec). Mechanisms in the correlator hardware design make it possible to split the total number of antennas in the array into smaller subsets, or sub-arrays, such that they can share correlator resources while executing independent observations. The software part of the sub-system is responsible for configuring and scheduling correlator resources in such a way that observations among independent subarrays occur simultaneously while internally sharing correlator resources under a cooperative arrangement. Configuration of correlator modes through its CAN-bus interface and periodic geometric delay updates are the most relevant activities to schedule concurrently while observations happen at the same time among a number of sub-arrays. For that to work correctly, the software interface to sub-arrays schedules shared correlator resources sequentially before observations actually start on each sub-array. Start times for specific observations are optimized and reported back to the higher level observing software. After that initial sequential phase has taken place then simultaneous executions and recording of correlated data across different sub-arrays move forward concurrently, sharing the local network to broadcast results to other software sub-systems. The present paper presents an overview of the different hardware and software actors within the correlator sub-system that implement some degree of concurrency and synchronization needed for seamless and simultaneous operation of multiple sub-arrays, limitations stemming from the resource-sharing nature of the correlator, limitations intrinsic to the digital technology available in the correlator hardware, and milestones so far reached by this new ALMA feature.

Spatiotemporal topology and temporal sequence identification with an adaptive time-delay neural network

NASA Astrophysics Data System (ADS)

Lin, Daw-Tung; Ligomenides, Panos A.; Dayhoff, Judith E.

1993-08-01

Inspired from the time delays that occur in neurobiological signal transmission, we describe an adaptive time delay neural network (ATNN) which is a powerful dynamic learning technique for spatiotemporal pattern transformation and temporal sequence identification. The dynamic properties of this network are formulated through the adaptation of time-delays and synapse weights, which are adjusted on-line based on gradient descent rules according to the evolution of observed inputs and outputs. We have applied the ATNN to examples that possess spatiotemporal complexity, with temporal sequences that are completed by the network. The ATNN is able to be applied to pattern completion. Simulation results show that the ATNN learns the topology of a circular and figure eight trajectories within 500 on-line training iterations, and reproduces the trajectory dynamically with very high accuracy. The ATNN was also trained to model the Fourier series expansion of the sum of different odd harmonics. The resulting network provides more flexibility and efficiency than the TDNN and allows the network to seek optimal values for time-delays as well as optimal synapse weights.

Achromatic registration of quadrature components of the optical spectrum in spectral domain optical coherence tomography

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

Shilyagin, P A; Gelikonov, G V; Gelikonov, V M

2014-07-31

We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phasemore » shift achromatism over a wide spectral range is achieved by using in the delay lines the individual elements with different dispersion characteristics. The ranges of admissible adjustment parameters of the achromatised delay line are estimated for exact and inexact conformity of the geometric characteristics of its components to those calculated. A possibility of simultaneous recording of the close-to-quadrature spectral components with a single linear photodetector element is experimentally confirmed. The suppression of the artefact mirror peak in the OCT-signal by an additional 9 dB relative to the level of its suppression is experimentally achieved when the air delay line is used. Two-dimensional images of the surface positioned at an angle to the axis of the probe beam are obtained with the correction of the 'mirror' artefact while maintaining the dynamic range of the image. (laser biophotonics)« less

The enigmatic WR46: A binary or a pulsator in disguise. II. The spectroscopy

NASA Astrophysics Data System (ADS)

Veen, P. M.; van Genderen, A. M.; Crowther, P. A.; van der Hucht, K. A.

2002-04-01

We present spectroscopic monitoring of the Wolf-Rayet (WR) star WR 46 between 1989 and 1998, which has been obtained simultaneously with multicolour photometry (Veen et al. \\cite{Veen02a}, Paper I). The spectroscopic monitoring data show that the radiative fluxes of the optical emission lines (O Vi 3811/34, O Vi 5290, N V 4944, N V 4604/20, He Ii 4686, He Ii 4859, He Ii 5411, He Ii 6560) vary in concert with the photometric single-wave (sw) frequency f_sw (Paper I), and also the difference of that period between 1989 and 1991. The line-flux variability does not provide obvious support for a short second period (Paper I). The radial-velocity variations show a remarkable behaviour: usually, they display a coherent single-wave on the time scale of the double-wave period, while during some nights the radial velocity appears surprisingly to stay constant (see also Marchenko et al. \\cite{Marchenko00}). These so-called stand-stills may be related to the observed time-delay effects. A time-delay effect manifests itself in several phenomena. Firstly, the line flux shows small, but persistent, time-delays for lines originating from lower optical depths, the outer-wind lines (N V 4604/20 and He Ii). Secondly, the radial-velocity variations display much larger time-delays than the line fluxes and their behaviour appears less consistent. Assuming that the double-wave period controls the radial velocity, the stand-still is observed to start when the radial motion is in anti-phase with the presumed orbital motion. Thirdly, the outer-wind lines are observed to enter a stand-still much later than the inner-wind lines. Fourthly, the radial-velocity variations of the peaks of the emission lines precede the radial-velocity variations of the wings of those lines. In addition to line-flux- and radial-velocity variability, the He Ii 4686 emission line shows pronounced line-profile changes on a time scale of hours. Our monitoring is not sufficient to study this in detail. Furthermore, we discern a flaring behaviour, i.e., an emission bump appeared on the blue wing of two He Ii-lines (around -1700 km s-1) lasting less than 5 min. Finally, the line fluxes follow the observed brightenings, also on a time scale of years. We conclude that the short-term cyclic variability confirms the WR nature as established from the WR standard model analysis by Crowther et al. (\\cite{Crowther95}; hereafter referred to as CSH). The various time-delay effects are consistent with the formation of the spectrum in a stratified stellar wind. The outer layers trail the inner ones. The variability is inconsistent with the formation of the spectrum in a stellar disc as proposed by Niemela et al. (\\cite{Niemela95}) and Steiner & Diaz (\\cite{Steiner98}). The long-term cyclic variability of the brightness and line fluxes is related to an increase of the mass-loss-rate, and, possibly, to the period changes. The interpretation of the nature of the variability is deferred to Veen et al. (\\cite{Veen02b}, Paper III). Based on observations collected at the European Southern Observatory (ESO), La Silla, Chile.

Development of an automated on-line pepsin digestion-liquid chromatography-tandem mass spectrometry configuration for the rapid analysis of protein adducts of chemical warfare agents.

PubMed

Carol-Visser, Jeroen; van der Schans, Marcel; Fidder, Alex; Hulst, Albert G; van Baar, Ben L M; Irth, Hubertus; Noort, Daan

2008-07-01

Rapid monitoring and retrospective verification are key issues in protection against and non-proliferation of chemical warfare agents (CWA). Such monitoring and verification are adequately accomplished by the analysis of persistent protein adducts of these agents. Liquid chromatography-mass spectrometry (LC-MS) is the tool of choice in the analysis of such protein adducts, but the overall experimental procedure is quite elaborate. Therefore, an automated on-line pepsin digestion-LC-MS configuration has been developed for the rapid determination of CWA protein adducts. The utility of this configuration is demonstrated by the analysis of specific adducts of sarin and sulfur mustard to human butyryl cholinesterase and human serum albumin, respectively.

Coaxial fast metal-to-metal switch for high current.

PubMed

Boissady, C; Rioux-Damidau, F

1978-11-01

A fast mechanical switch of coaxial configuration, driven by a magnetic field, is described. It presents a low inductance (6 nH), a low resistance (3 muOmega) and delay-times of 25 micros with a jitter of 0.08 micros.

Strut and wall interference on jet-induced ground effects of a STOVL aircraft in hover

NASA Technical Reports Server (NTRS)

Kristy, Michael H.

1995-01-01

A small scale ground effect test rig was used to study the ground plane flow field generated by a STOVL aircraft in hover. The objective of the research was to support NASA-Ames Research Center planning for the Large Scale Powered Model (LSPM) test for the ARPA-sponsored ASTOVL program. Specifically, small scale oil flow visualization studies were conducted to make a relative assessment of the aerodynamic interference of a proposed strut configuration and a wall configuration on the ground plane stagnation line. A simplified flat plate model representative of a generic jet-powered STOVL aircraft was used to simulate the LSPM. Cold air jets were used to simulate both the lift fan and the twin rear engines. Nozzle Pressure Ratios were used that closely represented those used on the LSPM tests. The flow visualization data clearly identified a shift in the stagnation line location for both the strut and the wall configuration. Considering the experimental uncertainty, it was concluded that either the strut configuration o r the wall configuration caused only a minor aerodynamic interference.

A collection of articles on S/X-band experiment zero delay ranging tests, volume 1

NASA Technical Reports Server (NTRS)

Otoshi, T. Y. (Editor)

1975-01-01

Articles are presented which are concerned with the development of special test equipment and a dual-frequency zero delay device (ZDD) that were required for range tests and the measurement of ground station delays for the Mariner-Venus-Mercury 1973 S/X-band experiment. Test data obtained at DSS 14 after installation of the ZDD on the 64-m antenna are given. It is shown that large variations of range were observed as a function of antenna elevation angle and were sensitive to antenna location. A ranging calibration configuration that was subsequently developed and a technique for determining the appropriate Z-correction are described. Zero delay test data at DSS 14 during the Mariner 10 Venus-Mercury-Encounter periods (1974 days 12-150) are presented. The theoretical analysis and experimental verifications are included of the effects of multipath and effects of discontinuities on range delay measurements. A movable subreflector technique and the multipath theory were used to isolate principal multipath errors on the 64-m antenna and to enable a more accurate determination of the actual ground station range delay.

Research on Spectroscopy, Opacity, and Atmospheres

NASA Technical Reports Server (NTRS)

Kurucz, Robert L.

2005-01-01

I propose to continue providing observers with basic data for interpreting spectra from stars, novas, supernovas, clusters, and galaxies. These data will include allowed and forbidden line lists, both laboratory and computed, for the first five to ten ions of all atoms and for all relevant diatomic molecules. I will eventually expand to all ions of the first thirty elements to treat far UV and X-ray spectra, and for envelope opacities. I also include triatomic molecules provided by other researchers. I have also made CDs with Partridge and Schwenke's water data for work on UV stars. The line data also serve as input to my model atmosphere and synthesis programs that generate energy distributions, photometry, limb darkening, and spectra that can be used for planning observations and for fitting observed spectra. The spectrum synthesis programs produce detailed plots with the lines identified. Grids of stellar spectra can be used for radial velocity-, rotation-, or abundance templates and for population synthesis. I am fitting spectra of bright stars to test the data and to produce atlases to guide observers. For each star the whole spectrum is computed from the UV to the far IR. The line data, opacities, models, spectra, and programs are freely distributed on CDs and on my Web site and represent a unique resource for many NASA programs. I am now in full production of new line lists for atoms. I am computing all ions of all elements from H to Zn and the first 5 ions of all the heavier elements, about 800 ions. For each ion I treat as many as 61 even and 61 odd configurations, computing all energy levels and eigenvectors. The Hamiltonian is determined from a scaled-Hartree-Fock starting guess by least squares fitting the observed energy levels. The average energy of each configuration is used in computing scaled-Thomas-Fermi-Dirac wavefunctions for each configuration which in turn are used to compute allowed and forbidden transition integrals. These are multiplied into the LS allowed and forbidden transition arrays. The transition arrays are transformed to the observed coupling to yield the allowed and forbidden line lists. Results are put on the web as they are finished. Provided I get funding,there will be more than 500 million lines. I will then compare ion by ion, to all the laboratory and computed data in the literature and make up a working line list for spectrum synthesis and opacity calculations with the best available data. As the laboratory spectrum analyses are improved, I will redo the calculations with the new energy levels. My original plan when I started the new calculations was to run through all the atoms using my old Cray programs from the 1980's that were limited to 1100 x 1100 arrays in the Hamiltonian for each J. Then I would go back and rerun the more complicated cases with 3000 x 3000 arrays so that I could include many more configurations and more configuration interactions. At present I am limited to 61 even and 61 odd configurations and I try to include everything up through n = 9. The current program runs on Alpha workstations. I decided to test the big program on Fe I and Fe II to see whether there was any great difference in the low configurations compared to those from the Cray program. Besides increasing the number of E1 lines by a factor of 6 to 7.7 million, there was an unexpected result: the electric quadrupole transitions were 10 times stronger than before because the transition integrals are weighted by r(exp 2) ---they become very large for high n, and because there are numerous configuration interactions that mix the low and high configurations. As a check I was able to reproduce Carstang's (1962) lower results by running his three configurations with my program. Since my model atom is still only a subset of a real Fe II ion, the true quadrupole A values are probably larger than mine. The magnetic dipole lines are affected by the mixing but the overall scale does not change. Because of this scovery I decided that there was no point in computing the small array cases. I have been running with as many configurations as I can and with thousands of parameters in the Hamiltonian. The computer runs take much longer to set up and produce than I had expected. I have concentrated on redoing the low iron group spectra, especially to get data for supernova modelers. I have done only Ca I -- Zn I, Ca II -- Zn II, CU I -- Cu XXIX, Zn I - Zn XXX, for practice at high stages of ionization, C I, C II, S I, and CL I and Ag I for people who were working on the laboratory spectra. Check my web site kurucz.harvard.edu for current additions. My latest calculations have been for carbon I and sulphur I, and silicon I is under way using the same elaborate approach as for C I, which took many months to do. These line lists greatly increase the number of lines in the ultraviolet, in the visible, and especially in the infrared. They will increase the opacity in A, F, and G stars. They will account for many unidentified lines in the sun.

True-time-delay photonic beamformer for an L-band phased array radar

NASA Astrophysics Data System (ADS)

Zmuda, Henry; Toughlian, Edward N.; Payson, Paul M.; Malowicki, John E.

1995-10-01

The problem of obtaining a true-time-delay photonic beamformer has recently been a topic of great interest. Many interesting and novel approaches to this problem have been studied. This paper examines the design, construction, and testing of a dynamic optical processor for the control of a 20-element phased array antenna operating at L-band (1.2-1.4 GHz). The approach taken here has several distinct advantages. The actual optical control is accomplished with a class of spatial light modulator known as a segmented mirror device (SMD). This allows for the possibility of controlling an extremely large number (tens of thousands) of antenna elements using integrated circuit technology. The SMD technology is driven by the HDTV and laser printer markets so ultimate cost reduction as well as technological improvements are expected. Optical splitting is efficiently accomplished using a diffractive optical element. This again has the potential for use in antenna array systems with a large number of radiating elements. The actual time delay is achieved using a single acousto-optic device for all the array elements. Acousto-optic device technologies offer sufficient delay as needed for a time steered array. The topological configuration is an optical heterodyne system, hence high, potentially millimeter wave center frequencies are possible by mixing two lasers of slightly differing frequencies. Finally, the entire system is spatially integrated into a 3D glass substrate. The integrated system provides the ruggedness needed in most applications and essentially eliminates the drift problems associated with free space optical systems. Though the system is presently being configured as a beamformer, it has the ability to operate as a general photonic signal processing element in an adaptive (reconfigurable) transversal frequency filter configuration. Such systems are widely applicable in jammer/noise canceling systems, broadband ISDN, and for spread spectrum secure communications. This paper also serves as an update of work-in-progress at the Rome Laboratory Photonics Center Optical Beamforming Lab. The multi-faceted aspects of the design and construction of this state-of-the-art beamforming project will be discussed. Experimental results which demonstrate the performance of the system to-date with regard to both maximum delay and resolution over a broad bandwidth are presented.

Kinetic parameters of the GUINEVERE reference configuration in VENUS-F reactor obtained from a pile noise experiment using Rossi and Feynman methods

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

Geslot, Benoit; Pepino, Alexandra; Blaise, Patrick

A pile noise measurement campaign has been conducted by the CEA in the VENUS-F reactor (SCK-CEN, Mol Belgium) in April 2011 in the reference critical configuration of the GUINEVERE experimental program. The experimental setup made it possible to estimate the core kinetic parameters: the prompt neutron decay constant, the delayed neutron fraction and the generation time. A precise assessment of these constants is of prime importance. In particular, the effective delayed neutron fraction is used to normalize and compare calculated reactivities of different subcritical configurations, obtained by modifying either the core layout or the control rods position, with experimental onesmore » deduced from the analysis of measurements. This paper presents results obtained with a CEA-developed time stamping acquisition system. Data were analyzed using Rossi-α and Feynman-α methods. Results were normalized to reactor power using a calibrated fission chamber with a deposit of Np-237. Calculated factors were necessary to the analysis: the Diven factor was computed by the ENEA (Italy) and the power calibration factor by the CNRS/IN2P3/LPC Caen. Results deduced with both methods are consistent with respect to calculated quantities. Recommended values are given by the Rossi-α estimator, that was found to be the most robust. The neutron generation time was found equal to 0.438 ± 0.009 μs and the effective delayed neutron fraction is 765 ± 8 pcm. Discrepancies with the calculated value (722 pcm, calculation from ENEA) are satisfactory: -5.6% for the Rossi-α estimate and -2.7% for the Feynman-α estimate. (authors)« less

Separation Assurance and Scheduling Coordination in the Arrival Environment

NASA Technical Reports Server (NTRS)

Aweiss, Arwa S.; Cone, Andrew C.; Holladay, Joshua J.; Munoz, Epifanio; Lewis, Timothy A.

2016-01-01

Separation assurance (SA) automation has been proposed as either a ground-based or airborne paradigm. The arrival environment is complex because aircraft are being sequenced and spaced to the arrival fix. This paper examines the effect of the allocation of the SA and scheduling functions on the performance of the system. Two coordination configurations between an SA and an arrival management system are tested using both ground and airborne implementations. All configurations have a conflict detection and resolution (CD&R) system and either an integrated or separated scheduler. Performance metrics are presented for the ground and airborne systems based on arrival traffic headed to Dallas/ Fort Worth International airport. The total delay, time-spacing conformance, and schedule conformance are used to measure efficiency. The goal of the analysis is to use the metrics to identify performance differences between the configurations that are based on different function allocations. A surveillance range limitation of 100 nmi and a time delay for sharing updated trajectory intent of 30 seconds were implemented for the airborne system. Overall, these results indicate that the surveillance range and the sharing of trajectories and aircraft schedules are important factors in determining the efficiency of an airborne arrival management system. These parameters are not relevant to the ground-based system as modeled for this study because it has instantaneous access to all aircraft trajectories and intent. Creating a schedule external to the CD&R and the scheduling conformance system was seen to reduce total delays for the airborne system, and had a minor effect on the ground-based system. The effect of an external scheduler on other metrics was mixed.

TASK ALLOCATION IN GEO-DISTRIBUTED CYBER-PHYSICAL SYSTEMS

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

Aggarwal, Rachit; Smidts, Carol

This paper studies the task allocation algorithm for a distributed test facility (DTF), which aims to assemble geo-distributed cyber (software) and physical (hardware in the loop components into a prototype cyber-physical system (CPS). This allows low cost testing on an early conceptual prototype (ECP) of the ultimate CPS (UCPS) to be developed. The DTF provides an instrumentation interface for carrying out reliability experiments remotely such as fault propagation analysis and in-situ testing of hardware and software components in a simulated environment. Unfortunately, the geo-distribution introduces an overhead that is not inherent to the UCPS, i.e. a significant time delay inmore » communication that threatens the stability of the ECP and is not an appropriate representation of the behavior of the UCPS. This can be mitigated by implementing a task allocation algorithm to find a suitable configuration and assign the software components to appropriate computational locations, dynamically. This would allow the ECP to operate more efficiently with less probability of being unstable due to the delays introduced by geo-distribution. The task allocation algorithm proposed in this work uses a Monte Carlo approach along with Dynamic Programming to identify the optimal network configuration to keep the time delays to a minimum.« less

Analytic relations for magnifications and time delays in gravitational lenses with fold and cusp configurations

NASA Astrophysics Data System (ADS)

Congdon, Arthur B.; Keeton, Charles R.; Nordgren, C. Erik

2008-09-01

Gravitational lensing provides a unique and powerful probe of the mass distributions of distant galaxies. Four-image lens systems with fold and cusp configurations have two or three bright images near a critical point. Within the framework of singularity theory, we derive analytic relations that are satisfied for a light source that lies a small but finite distance from the astroid caustic of a four-image lens. Using a perturbative expansion of the image positions, we show that the time delay between the close pair of images in a fold lens scales with the cube of the image separation, with a constant of proportionality that depends on a particular third derivative of the lens potential. We also apply our formalism to cusp lenses, where we develop perturbative expressions for the image positions, magnifications and time delays of the images in a cusp triplet. Some of these results were derived previously for a source asymptotically close to a cusp point, but using a simplified form of the lens equation whose validity may be in doubt for sources that lie at astrophysically relevant distances from the caustic. Along with the work of Keeton, Gaudi & Petters, this paper demonstrates that perturbation theory plays an important role in theoretical lensing studies.

14 CFR 1214.805 - Unforeseen customer delay.

Code of Federal Regulations, 2013 CFR

2013-01-01

... problem pose a threat of delay to the Shuttle launch schedule or critical off-line activities, NASA shall... availability of facilities, equipment, and personnel. In requesting NASA to make such special efforts, the customer shall agree to reimburse NASA the estimated additional cost incurred. ...

14 CFR 1214.805 - Unforeseen customer delay.

Code of Federal Regulations, 2011 CFR

2011-01-01

... problem pose a threat of delay to the Shuttle launch schedule or critical off-line activities, NASA shall... availability of facilities, equipment, and personnel. In requesting NASA to make such special efforts, the customer shall agree to reimburse NASA the estimated additional cost incurred. ...

14 CFR 1214.805 - Unforeseen customer delay.

Code of Federal Regulations, 2012 CFR

2012-01-01

... problem pose a threat of delay to the Shuttle launch schedule or critical off-line activities, NASA shall... availability of facilities, equipment, and personnel. In requesting NASA to make such special efforts, the customer shall agree to reimburse NASA the estimated additional cost incurred. ...

A Milestone for the VLT Interferometer

NASA Astrophysics Data System (ADS)

2000-10-01

Less than one month after "First Light" for the fourth 8.2-m YEPUN telescope ( ESO PR 18/00 ), another special moment occurred at ESO's Paranal Observatory. This time, it was the first truly "underground" event, in the 168-metre long Interferometric Tunnel that has been dug beneath the platform at the top of the mountain. As one staff member remarked on this occasion, it was something like "the first scheduled trip of the Paranal metro"! With the successful integration of the first Delay Line on Monday, September 25th, 2000, ESO has accomplished another important step towards the VLT Interferometer (VLTI). It will be followed by the integration of the second Delay Line by the end of November and the third is scheduled for February 2001; both are now in their final development phase in Europe. "VLTI First Light" is then expected to take place soon thereafter, by means of two small special telescopes ("siderostats"). The combination of the light beams from two of the 8.2-m Unit Telescopes will happen in mid-2001. The VLTI Delay Lines The VLTI Delay Lines form essential parts of this very complicated optical system. They serve to ensure that the light beams from several telescopes arrive in phase at the common interferometric focus. Details about how they function may be found in ESO PR 04/98. In order to achieve the necessary performance, ESO has worked with two Dutch contractors, Fokker Space and TNO-TPD - Netherlands Organization for Applied Scientific Research - Institute of Applied Physics , to arrive at a totally new Delay Line concept. Another Dutch participant in the VLTI project is the Nova-ESO VLTI Expertise Centre (NEVEC) , cf. ESO PR 14/00. The installation at Paranal The last twelve months have been very busy for the integration team, with much preparatory work at the VLTI buildings for the final installation of the Delay Line systems. The assembly of the translation mechanisms for the first two Delay Lines in the tunnel started in mid-2000. This included the alignment of their rails and supports to the extreme accuracy of about 0.25 mm over a total distance of 66.7 metres ( PR Photos 26a-b/00 ). To achieve such an unusually high precision, ESO - in collaboration with the French company FOGALE - developed a measurement system that is based on the water-level principle. The delicate assembly and alignment of the critical sub-systems of the Delay Line were undertaken with the support of Fokker Space and TPD/TNO ( PR Photo 26e/00 ). Also for this, state-of-the-art methods were required in order to ensure a stringent performance of the system. This includes optical alignment of the optics with an accuracy at the arcsec level and positioning of the linear motors at the 0.01 mm (10 µm) level. The Delay Line is one of the key systems in the VLT Interferometer. It is responsible for the compensation of the length of the optical path that is different from the individual telescopes. Extreme accuracy needed In the case of the VLT, this accuracy of the path length compensation must be within a tolerance of only 0.05 µm (0.00005 mm) over a distance of 120 metres. The present concept by ESO and the Dutch contractors is based on a retro-reflector (a "Cat's Eye") that is fixed on a carriage that runs on two stainless steel rails ( PR Photos 26c-d/00 ). The motion on these rails is performed by a 60 metres linear motor and a piezo-transducer element. They are controlled by a laser metrology system that measures the instantaneous distances betwen the mirrors with the required accuracy. This carriage is 2.5 metres long and weighs 250 kg. The total friction force is less than 50 grammes, thanks to the extreme accuracy of the rail alignment and special ball bearings. Because of this, the total power required for the Delay Line operation is only about 15 W. The mirrors of the retro-reflector are made of aluminium by REOSC (France). They have been coated with a single layer of gold for the best possible reflection at infrared wavelengths. This is the caption to ESO PR Photos 26a-e/00 . They may be reproduced, if credit is given to the European Southern Observatory. Note, however, that since these photos were electronically recorded and were primarily obtained to document the ongoing activities at Paranal, they are not of full professional quality for photographic reproduction.

Numerical modeling of crystal growth on a centrifuge for unstable natural convection configurations

NASA Technical Reports Server (NTRS)

Ramachandran, N.; Downey, J. P.; Curreri, P. A.; Jones, J. C.

1993-01-01

The fluid mechanics associated with crystal growth processes on centrifuges is modeled using 2D and 3D models. Two-dimensional calculations show that flow bifurcations exist in such crystal growth configurations where the ampoule is oriented in the same direction as the resultant gravity vector and a temperature gradient is imposed on the melt. A scaling analysis is formulated to predict the flow transition point from the natural convection dominated regime to the Coriolis force dominated regime. Results of 3D calculations are presented for two thermal configurations of the crystal growth cell: top heated and bottom heated with respect to the centrifugal acceleration. In the top heated configuration, a substantial reduction in the convection intensity within the melt can be attained by centrifuge operations, and close to steady diffusion-limited thermal conditions can be achieved over a narrow range of the imposed microgravity level. In the bottom heated configuration the Coriolis force has a stabilizing effect on fluid motion by delaying the onset of unsteady convection.

Care 3, Phase 1, volume 1

NASA Technical Reports Server (NTRS)

Stiffler, J. J.; Bryant, L. A.; Guccione, L.

1979-01-01

A computer program to aid in accessing the reliability of fault tolerant avionics systems was developed. A simple mathematical expression was used to evaluate the reliability of any redundant configuration over any interval during which the failure rates and coverage parameters remained unaffected by configuration changes. Provision was made for convolving such expressions in order to evaluate the reliability of a dual mode system. A coverage model was also developed to determine the various relevant coverage coefficients as a function of the available hardware and software fault detector characteristics, and subsequent isolation and recovery delay statistics.

Operating systems in the air transportation environment.

NASA Technical Reports Server (NTRS)

Cherry, G. W.

1971-01-01

Consideration of the problems facing air transport at present, and to be expected in the future. In the Northeast Corridor these problems involve community acceptance, airway and airport congestion and delays, passenger acceptance, noise reduction, and improvements in low-density short-haul economics. In the development of a superior short-haul operating system, terminal-configured vs cruise-configured vehicles are evaluated. CTOL, STOL, and VTOL aircraft of various types are discussed. In the field of noise abatement, it is shown that flight procedural techniques are capable of supplementing ?quiet engine' technology.

Consistency properties of chaotic systems driven by time-delayed feedback

NASA Astrophysics Data System (ADS)

Jüngling, T.; Soriano, M. C.; Oliver, N.; Porte, X.; Fischer, I.

2018-04-01

Consistency refers to the property of an externally driven dynamical system to respond in similar ways to similar inputs. In a delay system, the delayed feedback can be considered as an external drive to the undelayed subsystem. We analyze the degree of consistency in a generic chaotic system with delayed feedback by means of the auxiliary system approach. In this scheme an identical copy of the nonlinear node is driven by exactly the same signal as the original, allowing us to verify complete consistency via complete synchronization. In the past, the phenomenon of synchronization in delay-coupled chaotic systems has been widely studied using correlation functions. Here, we analytically derive relationships between characteristic signatures of the correlation functions in such systems and unequivocally relate them to the degree of consistency. The analytical framework is illustrated and supported by numerical calculations of the logistic map with delayed feedback for different replica configurations. We further apply the formalism to time series from an experiment based on a semiconductor laser with a double fiber-optical feedback loop. The experiment constitutes a high-quality replica scheme for studying consistency of the delay-driven laser and confirms the general theoretical results.

Distortion cancellation performance of miniature delay filters for feed-forward linear power amplifiers.

PubMed

Roy, Manas K

2002-11-01

The technique of feed-forward amplitude control has been widely used in the linearization of power amplifiers for wireless communication systems. In this technique, an error signal due to third order intermodulation distortion (IMD) is extracted, amplified, and used to correct the delayed main line distorted signal. For example, a miniature prototype base station for the Global System for Mobile Communications/Code Division Multiple Access (GSM/CDMA) cellular system uses feed-forward amplifiers with bulky and expensive coaxial cables, about 20 feet in length, to provide about 25 ns of delay. This paper shows alternate space-saving approaches of achieving these delays using three different types of delay filters: electromagnetic interdigital/lumped (<2.5"), ceramic (<1.8"), and ladder-type surface acoustic wave (SAW) (0.15"). The delay lines introduce phase and amplitude imbalance and delay mismatch in the linearization loop due to fabrication tolerances. These adversely affect the IMD cancellation. Using an RF system simulation tool, this paper critically compares the IMD cancellation performance achieved using the three technologies. Simulation results show that the optimization of delay mismatch can achieve the desired cancellation more easily than other parameters. It is shown that, if the critical system parameter (phase deviation from linearity), is maintained at <2.5 degrees peak-to-peak over a 20 MHz bandwidth in the frequency range 855 MHz to 875 MHz, one can achieve 25 dB of IMD cancellation performance. This paper concludes with the suggestion of a set of realistic specifications for a miniature delay filter for the low power loop of the feed-forward amplifier.

A Reverberation-based Black Hole Mass for MCG-06-30-15

NASA Astrophysics Data System (ADS)

Bentz, Misty C.; Cackett, Edward M.; Crenshaw, D. Michael; Horne, Keith; Street, Rachel; Ou-Yang, Benjamin

2016-10-01

We present the results of a reverberation campaign targeting MGC-06-30-15. Spectrophotometric monitoring and broad-band photometric monitoring over the course of four months in spring 2012 allowed a determination of a time delay in the broad Hβ emission line of τ = 5.3 ± 1.8 days in the rest frame of the active galactic nucleus (AGN). Combined with the width of the variable portion of the emission line, we determine a black hole mass of M BH = (1.6 ± 0.4) × 106 M ⊙. Both the Hβ time delay and the black hole mass are in good agreement with expectations from the R BLR-L and M BH-σ ⋆ relationships for other reverberation-mapped AGNs. The Hβ time delay is also in good agreement with the relationship between Hβ and broad-band near-IR delays, in which the effective size of the broad-line region is ˜4-5 times smaller than the inner edge of the dust torus. Additionally, the reverberation-based mass is in good agreement with estimates from the scaling relationship of the break in the X-ray power spectral density, and with constraints based on stellar kinematics derived from integral field spectroscopy of the inner ˜0.5 kpc of the galaxy.

Relationships between processing delay and microbial load of broiler neck skin samples.

PubMed

Lucianez, A; Holmes, M A; Tucker, A W

2010-01-01

The measurable microbial load on poultry carcasses during processing is determined by a number of factors including farm or origin, processing hygiene, and external temperature. This study investigated associations between carcass microbial load and progressive delays to processing. A total of 30 carcasses were delayed immediately after defeathering and before evisceration in a commercial abattoir in groups of five, and were held at ambient temperature for 1, 2, 3, 4, 6, and 8 h. Delayed carcasses were reintroduced to the processing line, and quantitative assessment of total viable count, coliforms, Staphylococcus aureus, and Pseudomonas spp. was undertaken on neck skin flap samples collected after carcass chilling and then pooled for each group. Sampling was repeated on 5 separate days, and the data were combined. Significant increases in total viable count (P = 0.001) and coliforms (P = 0.004), but not for S. aureus or Pseudomonas loads, were observed across the 8-h period of delay. In line with previous studies, there was significant variation in microbiological data according to sampling day. In conclusion, there is a significant and measurable decline in microbiological status of uneviscerated but defeathered poultry carcasses after an 8-h delay, but the variability of sampling results, reflecting the wide range of factors that impact microbial load, means that it is not possible to determine maximum or minimum acceptable periods of processing delay based on this criterion alone.

Differential effects of visual context on pattern discrimination by pigeons (Columba livia) and humans (Homo sapiens).

PubMed

Kelly, Debbie M; Cook, Robert G

2003-06-01

Three experiment examined the role of contextual information during line orientation and line position discriminations by pigeons (Columba livia) and humans (Homo sapiens). Experiment 1 tested pigeons' performance with these stimuli in a target localization task using texture displays. Experiments 2 and 3 tested pigeons and humans, respectively, with small and large variations of these stimuli in a same-different task. Humans showed a configural superiority effect when tested with displays constructed from large elements but not when tested with the smaller, more densely packed texture displays. The pigeons, in contrast, exhibited a configural inferiority effect when required to discriminate line orientation, regardless of stimulus size. These contrasting results suggest a species difference in the perceptionand use of features and contextual information in the discrimination of line information.

Energy management - The delayed flap approach

NASA Technical Reports Server (NTRS)

Bull, J. S.

1976-01-01

Flight test evaluation of a Delayed Flap approach procedure intended to provide reductions in noise and fuel consumption is underway using the NASA CV-990 test aircraft. Approach is initiated at a high airspeed (240 kt) and in a drag configuration that allows for low thrust. The aircraft is flown along the conventional ILS glide slope. A Fast/Slow message display signals the pilot when to extend approach flaps, landing gear, and land flaps. Implementation of the procedure in commercial service may require the addition of a DME navigation aid co-located with the ILS glide slope transmitter. The Delayed Flap approach saves 250 lb of fuel over the Reduced Flap approach, with a 95 EPNdB noise contour only 43% as large.

MOEMS optical delay line for optical coherence tomography

NASA Astrophysics Data System (ADS)

Choudhary, Om P.; Chouksey, S.; Sen, P. K.; Sen, P.; Solanki, J.; Andrews, J. T.

2014-09-01

Micro-Opto-Electro-Mechanical optical coherence tomography, a lab-on-chip for biomedical applications is designed, studied, fabricated and characterized. To fabricate the device standard PolyMUMPS processes is adopted. We report the utilization of electro-optic modulator for a fast scanning optical delay line for time domain optical coherence tomography. Design optimization are performed using Tanner EDA while simulations are performed using COMSOL. The paper summarizes various results and fabrication methodology adopted. The success of the device promises a future hand-held or endoscopic optical coherence tomography for biomedical applications.

Modeling of SAW Delay Lines

NASA Technical Reports Server (NTRS)

Wilson, William C.; Atkinson, Gary M.

2007-01-01

Integrated Vehicle Health Monitoring (IVHM) of aerospace vehicles requires rugged sensors having reduced volume, mass, and power that can be used to measure a variety of phenomena. Wireless systems are preferred when retro-fitting sensors onto existing vehicles. Surface Acoustic Wave (SAW) devices are capable of sensing: temperature, pressure, strain, chemical species, mass loading, acceleration, and shear stress. SAW technology is low cost, rugged, lightweight, and extremely low power. To aid in the development of SAW sensors for IVHM applications, a first order model of a SAW Delay line has been created.

Network Configuration Analysis for Formation Flying Satellites

NASA Technical Reports Server (NTRS)

Knoblock, Eric J.; Wallett, Thomas M.; Konangi, Vijay K.; Bhasin, Kul B.

2001-01-01

The performance of two networks to support autonomous multi-spacecraft formation flying systems is presented. Both systems are comprised of a ten-satellite formation, with one of the satellites designated as the central or 'mother ship.' All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/EP over ATM protocol architecture within the formation, and the second system uses the IEEE 802.11 protocol architecture within the formation. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IP queuing delay, IP queue size and IP processing delay at the mother ship as well as end-to-end delay for both systems. In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core.

PubMed

Lashkari, A; Khalafi, H; Kazeminejad, H

2013-05-01

In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR_PC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change.

Effective delayed neutron fraction and prompt neutron lifetime of Tehran research reactor mixed-core

PubMed Central

Lashkari, A.; Khalafi, H.; Kazeminejad, H.

2013-01-01

In this work, kinetic parameters of Tehran research reactor (TRR) mixed cores have been calculated. The mixed core configurations are made by replacement of the low enriched uranium control fuel elements with highly enriched uranium control fuel elements in the reference core. The MTR_PC package, a nuclear reactor analysis tool, is used to perform the analysis. Simulations were carried out to compute effective delayed neutron fraction and prompt neutron lifetime. Calculation of kinetic parameters is necessary for reactivity and power excursion transient analysis. The results of this research show that effective delayed neutron fraction decreases and prompt neutron lifetime increases with the fuels burn-up. Also, by increasing the number of highly enriched uranium control fuel elements in the reference core, the prompt neutron lifetime increases, but effective delayed neutron fraction does not show any considerable change. PMID:24976672

An FPGA Implementation of a Polychronous Spiking Neural Network with Delay Adaptation.

PubMed

Wang, Runchun; Cohen, Gregory; Stiefel, Klaus M; Hamilton, Tara Julia; Tapson, Jonathan; van Schaik, André

2013-01-01

We present an FPGA implementation of a re-configurable, polychronous spiking neural network with a large capacity for spatial-temporal patterns. The proposed neural network generates delay paths de novo, so that only connections that actually appear in the training patterns will be created. This allows the proposed network to use all the axons (variables) to store information. Spike Timing Dependent Delay Plasticity is used to fine-tune and add dynamics to the network. We use a time multiplexing approach allowing us to achieve 4096 (4k) neurons and up to 1.15 million programmable delay axons on a Virtex 6 FPGA. Test results show that the proposed neural network is capable of successfully recalling more than 95% of all spikes for 96% of the stored patterns. The tests also show that the neural network is robust to noise from random input spikes.

Quantification of calcium using localized normalization on laser-induced breakdown spectroscopy data

NASA Astrophysics Data System (ADS)

Sabri, Nursalwanie Mohd; Haider, Zuhaib; Tufail, Kashif; Aziz, Safwan; Ali, Jalil; Wahab, Zaidan Abdul; Abbas, Zulkifly

2017-03-01

This paper focuses on localized normalization for improved calibration curves in laser-induced breakdown spectroscopy (LIBS) measurements. The calibration curves have been obtained using five samples consisting of different concentrations of calcium (Ca) in potassium bromide (KBr) matrix. The work has utilized Q-switched Nd:YAG laser installed in LIBS2500plus system with fundamental wavelength and laser energy of 650 mJ. Optimization of gate delay can be obtained from signal-to-background ratio (SBR) of Ca II 315.9 and 317.9 nm. The optimum conditions are determined in which having high spectral intensity and SBR. The highest spectral lines of ionic and emission lines of Ca at gate delay of 0.83 µs. From SBR, the optimized gate delay is at 5.42 µs for both Ca II spectral lines. Calibration curves consist of three parts; original intensity from LIBS experimentation, normalization and localized normalization of the spectral line intensity. The R2 values of the calibration curves plotted using locally normalized intensities of Ca I 610.3, 612.2 and 616.2 nm spectral lines are 0.96329, 0.97042, and 0.96131, respectively. The enhancement from calibration curves using the regression coefficient allows more accurate analysis in LIBS. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 24 May 2017.

14 CFR § 1214.805 - Unforeseen customer delay.

Code of Federal Regulations, 2014 CFR

2014-01-01

... problem pose a threat of delay to the Shuttle launch schedule or critical off-line activities, NASA shall... availability of facilities, equipment, and personnel. In requesting NASA to make such special efforts, the customer shall agree to reimburse NASA the estimated additional cost incurred. ...

A Novel 2-D Programmable Photonic Time Delay Device for MM-Wave Signal Processing Applications

NASA Technical Reports Server (NTRS)

Yao, X.; Maleki, L.

1994-01-01

We describe a novel programmable photonic true time delay device that has the properties of low loss, inherent two dimensionality with a packing density exceeding 25 lines/cm super 2, virtually infinite bandwidth, and is easy to manufacture.

Load balancing strategy and its lookup-table enhancement in deterministic space delay/disruption tolerant networks

NASA Astrophysics Data System (ADS)

Huang, Jinhui; Liu, Wenxiang; Su, Yingxue; Wang, Feixue

2018-02-01

Space networks, in which connectivity is deterministic and intermittent, can be modeled by delay/disruption tolerant networks. In space delay/disruption tolerant networks, a packet is usually transmitted from the source node to the destination node indirectly via a series of relay nodes. If anyone of the nodes in the path becomes congested, the packet will be dropped due to buffer overflow. One of the main reasons behind congestion is the unbalanced network traffic distribution. We propose a load balancing strategy which takes the congestion status of both the local node and relay nodes into account. The congestion status, together with the end-to-end delay, is used in the routing selection. A lookup-table enhancement is also proposed. The off-line computation and the on-line adjustment are combined together to make a more precise estimate of the end-to-end delay while at the same time reducing the onboard computation. Simulation results show that the proposed strategy helps to distribute network traffic more evenly and therefore reduces the packet drop ratio. In addition, the average delay is also decreased in most cases. The lookup-table enhancement provides a compromise between the need for better communication performance and the desire for less onboard computation.

Absolute Configuration of Andrographolide and Its Proliferation of Osteoblast Cell Lines

NASA Astrophysics Data System (ADS)

Chantrapromma, S.; Boonnak, N.; Pitakpornpreecha, T.; Yordthong, T.; Chidan Kumar, C. S.; Fun, H. K.

2018-05-01

Andrographolide, C20H30O5, is a labdane diterpenoid which was isolated from the leave of Andrographis paniculata. Its crystal structure is determined by single crystal X-ray diffraction: monoclinic, sp. gr. P21, Z = 2. Absolute configuration is determined by the refinement of the Flack parameter to 0.21(19). In the crystal, molecules are linked by O-H···O hydrogen bonds and C-H···O interactions into two dimensional network parallel to the (001) plane. Its proliferation of osteoblast cell lines is reported.

First-principles studies of chromium line-ordered alloys in a molybdenum disulfide monolayer

NASA Astrophysics Data System (ADS)

Andriambelaza, N. F.; Mapasha, R. E.; Chetty, N.

2017-08-01

Density functional theory calculations have been performed to study the thermodynamic stability, structural and electronic properties of various chromium (Cr) line-ordered alloy configurations in a molybdenum disulfide (MoS2) hexagonal monolayer for band gap engineering. Only the molybdenum (Mo) sites were substituted at each concentration in this study. For comparison purposes, different Cr line-ordered alloy and random alloy configurations were studied and the most thermodynamically stable ones at each concentration were identified. The configurations formed by the nearest neighbor pair of Cr atoms are energetically most favorable. The line-ordered alloys are constantly lower in formation energy than the random alloys at each concentration. An increase in Cr concentration reduces the lattice constant of the MoS2 system following the Vegard’s law. From density of states analysis, we found that the MoS2 band gap is tunable by both the Cr line-ordered alloys and random alloys with the same magnitudes. The reduction of the band gap is mainly due to the hybridization of the Cr 3d and Mo 4d orbitals at the vicinity of the band edges. The band gap engineering and magnitudes (1.65 eV to 0.86 eV) suggest that the Cr alloys in a MoS2 monolayer are good candidates for nanotechnology devices.

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

Hannan, N. A.; Matos, J. E.; Stillman, J. A.

At the request of the Czech Technical University (CTU) in Prague, ANL has performed independent verification calculations using the MCNP Monte Carlo code for three core configurations of the VR-1 reactor: a current core configuration B1 with HEU (36%) IRT-3M fuel assemblies and planned core configurations C1 and C2 with LEU (19.7%) IRT-4M fuel assemblies. Details of these configurations were provided to ANL by CTU. For core configuration B1, criticality calculations were performed for two sets of control rod positions provided to ANL by CTU. Fore core configurations C1 and C2, criticality calculations were done for cases with all controlmore » rods at the top positions, all control rods at the bottom positions, and two critical states of the reactor for different control rod positions. In addition, sensitivity studies for variation of the {sup 235}U mass in each fuel assembly and variation of the fuel meat and cladding thicknesses in each of the fuel tubes were doe for the C1 core configuration. The reactivity worth of the individual control rods was calculated for the B1, C1, and C2 core configurations. Finally, the reactivity feedback coefficients, the prompt neutron lifetime, and the total effective delay neutron fraction were calculated for each of the three cores.« less

Optical data packet synchronization and multiplexing using a tunable optical delay based on wavelength conversion and inter-channel chromatic dispersion.

PubMed

Fazal, Irfan; Yilmaz, Omer; Nuccio, Scott; Zhang, Bo; Willner, Alan E; Langrock, Carsten; Fejer, Martin M

2007-08-20

10 Gb/s non-return-to-zero (NRZ) on-off keyed (OOK) optical data packets are synchronized and time-multiplexed using a 26-ns tunable all-optical delay line. The delay element is based on wavelength conversion in periodically poled lithium niobate (PPLN) waveguides, inter-channel chromatic dispersion in dispersion compensating fiber (DCF) and intra-channel dispersion compensation with a chirped fiber Bragg grating (FBG). Delay reconfiguration time is measured to be less than 300 ps.

Combinational logic for generating gate drive signals for phase control rectifiers

NASA Technical Reports Server (NTRS)

Dolland, C. R.; Trimble, D. W. (Inventor)

1982-01-01

Control signals for phase-delay rectifiers, which require a variable firing angle that ranges from 0 deg to 180 deg, are derived from line-to-line 3-phase signals and both positive and negative firing angle control signals which are generated by comparing current command and actual current. Line-to-line phases are transformed into line-to-neutral phases and integrated to produce 90 deg phase delayed signals that are inverted to produce three cosine signals, such that for each its maximum occurs at the intersection of positive half cycles of the other two phases which are inputs to other inverters. At the same time, both positive and negative (inverted) phase sync signals are generated for each phase by comparing each with the next and producing a square wave when it is greater. Ramp, sync and firing angle controls signals are than used in combinational logic to generate the gate firing control signals SCR gate drives which fire SCR devices in a bridge circuit.

Delayed fission of atomic nuclei (To the 50th anniversary of the discovery)

NASA Astrophysics Data System (ADS)

Skobelev, N. K.

2017-09-01

The history of the discovery of delayed nuclear fission is presented, and the retrospective of investigations into this phenomenon that were performed at various research centers worldwide is outlined. The results obtained by measuring basic delayed-fission features, including the fission probability, the total kinetic energy of fission fragments, and their mass distributions, are analyzed. Recommendations concerning further studies in various regions of nuclear map with the aim of searches for and investigation of atomic nuclei undergoing delayed fission are given. Lines of further research into features of delayed fission with the aim of solving current problems of fission physics are discussed.

Delayed luminescence in a multiparameter approach to evaluation and reduction of radiobiological risks

NASA Astrophysics Data System (ADS)

Grasso, Rosaria; Cammarata, Francesco Paolo; Minafra, Luigi; Marchese, Valentina; Russo, Giorgio; Manti, Lorenzo; Musumeci, Francesco; Scordino, Agata

2017-07-01

In the framework of the research project ETHICS "Pre-clinical experimental and theoretical studies to improve treatment and protection by charged particles" funded by the National Nuclear Physics Institute, Italy, we studied the phenomenon called delayed luminescence emitted by non-tumorigenic breast epithelial MCF10A cell line after proton irradiation at different doses (0.5, 2, 6, 9 Gy). The aim is to found possible correlations between delayed luminescence and in vitro damaging induced by ion irradiation. The first results of this research show that the delayed luminescence kinetics is proton dose dependent. An interesting correlation between delayed luminescence and clonogenic potential was observed.

Acoustic Signal Processing in Photorefractive Optical Systems.

NASA Astrophysics Data System (ADS)

Zhou, Gan

This thesis discusses applications of the photorefractive effect in the context of acoustic signal processing. The devices and systems presented here illustrate the ideas and optical principles involved in holographic processing of acoustic information. The interest in optical processing stems from the similarities between holographic optical systems and contemporary models for massively parallel computation, in particular, neural networks. An initial step in acoustic processing is the transformation of acoustic signals into relevant optical forms. A fiber-optic transducer with photorefractive readout transforms acoustic signals into optical images corresponding to their short-time spectrum. The device analyzes complex sound signals and interfaces them with conventional optical correlators. The transducer consists of 130 multimode optical fibers sampling the spectral range of 100 Hz to 5 kHz logarithmically. A physical model of the human cochlea can help us understand some characteristics of human acoustic transduction and signal representation. We construct a life-sized cochlear model using elastic membranes coupled with two fluid-filled chambers, and use a photorefractive novelty filter to investigate its response. The detection sensitivity is determined to be 0.3 angstroms per root Hz at 2 kHz. Qualitative agreement is found between the model response and physiological data. Delay lines map time-domain signals into space -domain and permit holographic processing of temporal information. A parallel optical delay line using dynamic beam coupling in a rotating photorefractive crystal is presented. We experimentally demonstrate a 64 channel device with 0.5 seconds of time-delay and 167 Hz bandwidth. Acoustic signal recognition is described in a photorefractive system implementing the time-delay neural network model. The system consists of a photorefractive optical delay-line and a holographic correlator programmed in a LiNbO_3 crystal. We demonstrate the recognition of synthesized chirps as well as spoken words. A photorefractive ring resonator containing an optical delay line can learn temporal information through self-organization. We experimentally investigate a system that learns by itself and picks out the most-frequently -presented signals from the input. We also give results demonstrating the separation of two orthogonal temporal signals into two competing ring resonators.

Optics of Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): Delay Lines and Alignment

NASA Technical Reports Server (NTRS)

Dhabal, Arnab; Rinehart, Stephen A.; Rizzo, Maxime J.; Mundy, Lee; Fixsen, Dale; Sampler, Henry; Mentzell, Eric; Veach, Todd; Silverberg, Robert F.; Furst, Stephen;

Delayed luminescence to monitor programmed cell death induced by berberine on thyroid cancer cells

NASA Astrophysics Data System (ADS)

Scordino, Agata; Campisi, Agata; Grasso, Rosaria; Bonfanti, Roberta; Gulino, Marisa; Iauk, Liliana; Parenti, Rosalba; Musumeci, Francesco

2014-11-01

Correlation between apoptosis and UVA-induced ultraweak photon emission delayed luminescence (DL) from tumor thyroid cell lines was investigated. In particular, the effects of berberine, an alkaloid that has been reported to have anticancer activities, on two cancer cell lines were studied. The FTC-133 and 8305C cell lines, as representative of follicular and anaplastic thyroid human cancer, respectively, were chosen. The results show that berberine is able to arrest cell cycle and activate apoptotic pathway as shown in both cell lines by deoxyribonucleic acid fragmentation, caspase-3 cleavage, p53 and p27 protein overexpression. In parallel, changes in DL spectral components after berberine treatment support the hypothesis that DL from human cells originates mainly from mitochondria, since berberine acts especially at the mitochondrial level. The decrease of DL blue component for both cell lines could be related to the decrease of intra-mitochondrial nicotinamide adenine dinucleotide and may be a hallmark of induced apoptosis. In contrast, the response in the red spectral range is different for the two cell lines and may be ascribed to a different iron homeostasis.

Delayed Cell Cycle Progression and Apoptosis Induced by Hemicellulase-Treated Agaricus blazei

PubMed Central

Kasai, Hirotake

2007-01-01

We examined the effects of hemicellulase-treated Agaricus blazei (AB fraction H, ABH) on growth of several tumor cell lines. ABH inhibited the proliferation of some cell lines without cytotoxic effects. It markedly prolonged the S phase of the cell cycle. ABH also induced mitochondria-mediated apoptosis in different cell lines. However, it had no impact on the growth of other cell lines. ABH induced strong activation of p38 mitogen-activated protein kinase (MAPK) in the cells in which it evoked apoptosis. On the other hand, ABH showed only a weak p38 activation effect in those cell lines in which it delayed cell cycle progression with little induction of apoptosis. However, p38 MAPK-specific inhibitor inhibited both ABH-induced effects, and ABH also caused apoptosis in the latter cells under conditions of high p38 MAPK activity induced by combined treatment with TNF-α. These results indicate that the responsiveness of p38 MAPK to ABH, which differs between cell lines, determines subsequent cellular responses on cell growth. PMID:17342245

Tactical STOL moment balance through innovative configuration technology

NASA Technical Reports Server (NTRS)

Eckard, G. J.; Sutton, R. C.; Poth, G. E.

1981-01-01

Innovative and conventional thrust vectoring moment balance mechanisms, as applied to advanced tactical fighters, are examined. The innovative mechanisms include thrust line translation, life line translation, and auxiliary power control; the conventional mechanisms under investigation are horizontal tails, canards, and variable sweep wings. These mechanisms are tested for their ability to provide negative static margins for landing approach or relocation of the vectored thrust line nearer the aircraft's center of gravity. The net pitching moment due to wing, flaps, and vectored thrust lift would then be small, making possible beneficial trim forces from small trimming devices. These innovative mechanisms are, however, possibly heavy and must be evaluated on their complexity, reliability, maintainability, and STOL capabilities. Several candidate fighter configurations are compared and evaluated.

Power plant including an exhaust gas recirculation system for injecting recirculated exhaust gases in the fuel and compressed air of a gas turbine engine

DOEpatents

Anand, Ashok Kumar; Nagarjuna Reddy, Thirumala Reddy; Shaffer, Jason Brian; York, William David

2014-05-13

A power plant is provided and includes a gas turbine engine having a combustor in which compressed gas and fuel are mixed and combusted, first and second supply lines respectively coupled to the combustor and respectively configured to supply the compressed gas and the fuel to the combustor and an exhaust gas recirculation (EGR) system to re-circulate exhaust gas produced by the gas turbine engine toward the combustor. The EGR system is coupled to the first and second supply lines and configured to combine first and second portions of the re-circulated exhaust gas with the compressed gas and the fuel at the first and second supply lines, respectively.

Negative ion formation and evolution in atmospheric pressure corona discharges between point-to-plane electrodes with arbitrary needle angle

NASA Astrophysics Data System (ADS)

Sekimoto, K.; Takayama, M.

2010-12-01

The change in the distribution pattern of negative ions HO-, NOx- and COx- observed on arbitrary point-to-plane electrode configuration has been investigated by varying the angle of needle to the plane electrode, under atmospheric pressure corona discharge conditions. The stationary inhomogeneous electric field distributions between the point-to-plane electrodes with arbitrary needle angle were calculated. The experimental and theoretical results obtained suggested that the negative ion evolutions progress along field lines established between the electrodes with arbitrary configurations and the resulting terminal ion formation on a given field line is attributable to the electric field strength on the needle tip surface where the field line arose. The NOx- and COx- ions were dominantly produced on the field lines arising from the needle tip apex region with the highest electric field strength, while the field lines emanating from the tip peripheral regions with lower field strength resulted in the formation of the HO- ion.

An ultrasonic pseudorandom signal-correlation system

NASA Astrophysics Data System (ADS)

Elias, C. M.

1980-01-01

A working ultrasonic pseudorandom signal-correlation system is described which, unlike ultrasonic random signal-correlation systems, does not require an acoustic delay line. Elimination of the delay line allows faster data acquisition and better range resolution. The system uses two identical shift-register type generators to produce pseudonoise bursts which are subsequences of a 65 535-bit complementary m-sequence. One generator produces the transmitted bursts while the other generates identical reference bursts which start at a variable correlation delay time after the transmitted bursts. The reference bursts are cross-correlated with the received echoes to obtain the approximate impulse response of the transducer/specimen system under test. Range sidelobes are reduced by transmitting and correlating many bursts at a given correlation delay before incrementing the delay. Signal-to-sidelobe ratios of greater than 47 dB have been obtained using this method. Limitations of the system due to sampling constraints and the pseudonoise power spectrum are discussed, and the system design and implementation are outlined. Results of experimental characterization of the system show that the pseudorandom signal-correlation system has approximately the same range resolution as a conventional pulse-echo system but can yield a significant increase in signal-to-noise ratio (SNR).

Design of a microfluidic cell using microstereolithography for electronic tongue applications

NASA Astrophysics Data System (ADS)

Jacesko, Stefany L.; Ji, Taeksoo; Abraham, Jose K.; Varadan, Vijay K.; Gardner, Julian W.

2003-07-01

In this paper we present design, fabrication and integration of a micro fluidic cell for use with the electronic tongue. The cell was machined using microstereo lithography on a Hexanediol Diacrylate (HDDA) liquid monomer. The wet cell was designed to confine the liquid under test to the sensing area and insure complete isolation of the interdigital transducers (IDTs). The electronic tongue is a shear horizontal surface acoustic wave (SH-SAW) device. Shear horizontally polarized Love-waves are guided between transmitting and receiving IDTs, over a piezoelectric substrate, which creates an electronic oscillator effect. This device has a dual delay line configuration, which accounts for the measuring of both mechanical and electrical properties of a liquid, simultaneously, with the ability to eliminate environmental factors. The data collected is distinguished using principal components analysis in conjunction with pre-processing parameters. The experiments show that the micro fluidic cell for this electronic tongue does not affect the losses or phase of the device to any extent of concern. Experiments also show that liquids such as Strawberry Hi-C, Teriyaki Sauce, DI Water, Coca Cola, and Pepsi are distinguishable using these methods.

Strongly anomalous diffusion in sheared magnetic configurations

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

Vanden Eijnden, E.; Balescu, R.

1996-03-01

The statistical behavior of magnetic lines in a sheared magnetic configuration with reference surface {ital x}=0 is investigated within the framework of the kinetic theory. A Liouville equation is associated with the equations of motion of the stochastic magnetic lines. After averaging over an ensemble of realizations, it yields a convection-diffusion equation within the quasilinear approximation. The diffusion coefficients are space dependent and peaked around the reference surface {ital x}=0. Due to the shear, the diffusion of lines away from the reference surface is slowed down. The behavior of the lines is asymptotically strongly non-Gaussian. The reference surface acts likemore » an attractor around which the magnetic lines spread with an effective subdiffusive behavior. Comparison is also made with more usual treatments based on the study of the first two moments equations. For sheared systems, it is explicitly shown that the Corrsin approximation assumed in the latter approach is no longer valid. It is also concluded that the diffusion coefficients cannot be derived from the mean square displacement of the magnetic lines in an inhomogeneous medium. {copyright} {ital 1996 American Institute of Physics.}« less

On-line, continuous monitoring in solar cell and fuel cell manufacturing using spectral reflectance imaging

DOEpatents

Sopori, Bhushan; Rupnowski, Przemyslaw; Ulsh, Michael

2016-01-12

A monitoring system 100 comprising a material transport system 104 providing for the transportation of a substantially planar material 102, 107 through the monitoring zone 103 of the monitoring system 100. The system 100 also includes a line camera 106 positioned to obtain multiple line images across a width of the material 102, 107 as it is transported through the monitoring zone 103. The system 100 further includes an illumination source 108 providing for the illumination of the material 102, 107 transported through the monitoring zone 103 such that light reflected in a direction normal to the substantially planar surface of the material 102, 107 is detected by the line camera 106. A data processing system 110 is also provided in digital communication with the line camera 106. The data processing system 110 is configured to receive data output from the line camera 106 and further configured to calculate and provide substantially contemporaneous information relating to a quality parameter of the material 102, 107. Also disclosed are methods of monitoring a quality parameter of a material.

FRIB Cryogenic Distribution System and Status

NASA Astrophysics Data System (ADS)

Ganni, V.; Dixon, K.; Laverdure, N.; Yang, S.; Nellis, T.; Jones, S.; Casagrande, F.

2015-12-01

The MSU-FRIB cryogenic distribution system supports the 2 K primary, 4 K primary, and 35 - 55 K shield operation of more than 70 loads in the accelerator and the experimental areas. It is based on JLab and SNS experience with bayonet-type disconnects between the loads and the distribution system for phased commissioning and maintenance. The linac transfer line, which features three separate transfer line segments for additional independence during phased commissioning at 4 K and 2 K, connects the folded arrangement of 49 cryomodules and 4 superconducting dipole magnets and a fourth transfer line supports the separator area cryo loads. The pressure reliefs for the transfer line process lines, located in the refrigeration room outside the tunnel/accelerator area, are piped to be vented outdoors. The transfer line designs integrate supply and return flow paths into a combined vacuum space. The main linac distribution segments are produced in a small number of standard configurations; a prototype of one such configuration has been fabricated at Jefferson Lab and has been installed at MSU to support testing of a prototype FRIB cryomodule.

A micromachined silicon parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT)

NASA Astrophysics Data System (ADS)

Cho, Young Y.; Chang, Cheng-Chung; Wang, Lihong V.; Zou, Jun

2015-03-01

To achieve real-time photoacoustic tomography (PAT), massive transducer arrays and data acquisition (DAQ) electronics are needed to receive the PA signals simultaneously, which results in complex and high-cost ultrasound receiver systems. To address this issue, we have developed a new PA data acquisition approach using acoustic time delay. Optical fibers were used as parallel acoustic delay lines (PADLs) to create different time delays in multiple channels of PA signals. This makes the PA signals reach a single-element transducer at different times. As a result, they can be properly received by single-channel DAQ electronics. However, due to their small diameter and fragility, using optical fiber as acoustic delay lines poses a number of challenges in the design, construction and packaging of the PADLs, thereby limiting their performances and use in real imaging applications. In this paper, we report the development of new silicon PADLs, which are directly made from silicon wafers using advanced micromachining technologies. The silicon PADLs have very low acoustic attenuation and distortion. A linear array of 16 silicon PADLs were assembled into a handheld package with one common input port and one common output port. To demonstrate its real-time PAT capability, the silicon PADL array (with its output port interfaced with a single-element transducer) was used to receive 16 channels of PA signals simultaneously from a tissue-mimicking optical phantom sample. The reconstructed PA image matches well with the imaging target. Therefore, the silicon PADL array can provide a 16× reduction in the ultrasound DAQ channels for real-time PAT.

Imprints of the quasar structure in time-delay light curves: Microlensing-aided reverberation mapping

NASA Astrophysics Data System (ADS)

Sluse, D.; Tewes, M.

2014-11-01

The advent of large area photometric surveys has raised a great deal of interest in the possibility of using broadband photometric data, instead of spectra, to measure the size of the broad line region of active galactic nuclei. We describe here a new method that uses time-delay lensed quasars where one or several images are affected by microlensing due to stars in the lensing galaxy. Because microlensing decreases (or increases) the flux of the continuum compared to the broad line region, it changes the contrast between these two emission components. We show that this effect can be used to effectively disentangle the intrinsic variability of those two regions, offering the opportunity to perform reverberation mapping based on single-band photometric data. Based on simulated light curves generated using a damped random walk model of quasar variability, we show that measurement of the size of the broad line region can be achieved using this method, provided one spectrum has been obtained independently during the monitoring. This method is complementary to photometric reverberation mapping and could also be extended to multi-band data. Because the effect described above produces a variability pattern in difference light curves between pairs of lensed images that is correlated with the time-lagged continuum variability, it can potentially produce systematic errors in measurement of time delays between pairs of lensed images. Simple simulations indicate that time-delay measurement techniques that use a sufficiently flexible model for the extrinsic variability are not affected by this effect and produce accurate time delays.

Delayed and Unreported Drug-Susceptibility Testing Results in the US National Tuberculosis Surveillance System, 1993-2014.

PubMed

Jones, Jefferson Michael; Armstrong, Lori R

Drug-susceptibility testing (DST) of Mycobacterium tuberculosis is necessary for identifying drug-resistant tuberculosis, administering effective treatment regimens, and preventing the spread of drug-resistant tuberculosis. DST is recommended for all culture-confirmed cases of tuberculosis. We examined trends in delayed and unreported DST results in the Centers for Disease Control and Prevention's National Tuberculosis Surveillance System. We analyzed culture-confirmed tuberculosis cases reported to the National Tuberculosis Surveillance System during 1993-2014 for annual trends in initial DST reporting for first-line antituberculosis drugs and trends in on-time, delayed, and unreported results. We defined on-time reporting as DST results received during the same calendar year in which the patient's case was reported or ≤4 months after the calendar year ended and delayed reporting as DST results received after the calendar year. We compared cases with on-time, delayed, and unreported DST results by patient and tuberculosis program characteristics. The proportion of cases with reported results for all first-line antituberculosis drugs increased during 1993-2011. Reporting of pyrazinamide results was lower than reporting of other drugs. However, during 2000-2012, of 134 787 tuberculosis cases reported to the National Tuberculosis Surveillance System, reporting was on time for 125 855 (93.4%) cases, delayed for 5332 (4.0%) cases, and unreported for 3600 (2.7%) cases. Despite increases in the proportion of cases with on-time DST results, delayed and unreported results persisted. Carefully assessing causes for delayed and unreported DST results should lead to more timely reporting of drug-resistant tuberculosis.

Delay Discounting and Intelligence: A Meta-Analysis

ERIC Educational Resources Information Center

Shamosh, Noah A.; Gray, Jeremy R.

2008-01-01

Delay discounting (DD), the tendency to prefer smaller, sooner rewards to larger, later ones, is an important indicator of self-control. Assessments of DD superficially require individuals to make choices based on motivational processes. However, several lines of evidence suggest that DD may be systematically related to cognitive ability. We…

New Paranal Views

NASA Astrophysics Data System (ADS)

2001-01-01

Last year saw very good progress at ESO's Paranal Observatory , the site of the Very Large Telescope (VLT). The third and fourth 8.2-m Unit Telescopes, MELIPAL and YEPUN had "First Light" (cf. PR 01/00 and PR 18/00 ), while the first two, ANTU and KUEYEN , were busy collecting first-class data for hundreds of astronomers. Meanwhile, work continued towards the next phase of the VLT project, the combination of the telescopes into the VLT Interferometer. The test instrument, VINCI (cf. PR 22/00 ) is now being installed in the VLTI Laboratory at the centre of the observing platform on the top of Paranal. Below is a new collection of video sequences and photos that illustrate the latest developments at the Paranal Observatory. The were obtained by the EPR Video Team in December 2000. The photos are available in different formats, including "high-resolution" that is suitable for reproduction purposes. A related ESO Video News Reel for professional broadcasters will soon become available and will be announced via the usual channels. Overview Paranal Observatory (Dec. 2000) Video Clip 02a/01 [MPEG - 4.5Mb] ESO PR Video Clip 02a/01 "Paranal Observatory (December 2000)" (4875 frames/3:15 min) [MPEG Video+Audio; 160x120 pix; 4.5Mb] [MPEG Video+Audio; 320x240 pix; 13.5 Mb] [RealMedia; streaming; 34kps] [RealMedia; streaming; 200kps] ESO Video Clip 02a/01 shows some of the construction activities at the Paranal Observatory in December 2000, beginning with a general view of the site. Then follow views of the Residencia , a building that has been designed by Architects Auer and Weber in Munich - it integrates very well into the desert, creating a welcome recreational site for staff and visitors in this harsh environment. The next scenes focus on the "stations" for the auxiliary telescopes for the VLTI and the installation of two delay lines in the 140-m long underground tunnel. The following part of the video clip shows the start-up of the excavation work for the 2.6-m VLT Survey Telescope (VST) as well as the location known as the "NTT Peak", now under consideration for the installation of the 4-m VISTA telescope. The last images are from to the second 8.2-m Unit Telescope, KUEYEN, that has been in full use by the astronomers with the UVES and FORS2 instruments since April 2000. ESO PR Photo 04a/01 ESO PR Photo 04a/01 [Preview - JPEG: 466 x 400 pix - 58k] [Normal - JPEG: 931 x 800 pix - 688k] [Hires - JPEG: 3000 x 2577 pix - 7.6M] Caption : PR Photo 04a/01 shows an afternoon view from the Paranal summit towards East, with the Base Camp and the new Residencia on the slope to the right, above the valley in the shadow of the mountain. ESO PR Photo 04b/01 ESO PR Photo 04b/01 [Preview - JPEG: 791 x 400 pix - 89k] [Normal - JPEG: 1582 x 800 pix - 1.1Mk] [Hires - JPEG: 3000 x 1517 pix - 3.6M] PR Photo 04b/01 shows the ramp leading to the main entrance to the partly subterranean Residencia , with the steel skeleton for the dome over the central area in place. ESO PR Photo 04c/01 ESO PR Photo 04c/01 [Preview - JPEG: 498 x 400 pix - 65k] [Normal - JPEG: 995 x 800 pix - 640k] [Hires - JPEG: 3000 x 2411 pix - 6.6M] PR Photo 04c/01 is an indoor view of the reception hall under the dome, looking towards the main entrance. ESO PR Photo 04d/01 ESO PR Photo 04d/01 [Preview - JPEG: 472 x 400 pix - 61k] [Normal - JPEG: 944 x 800 pix - 632k] [Hires - JPEG: 3000 x 2543 pix - 5.8M] PR Photo 04d/01 shows the ramps from the reception area towards the rooms. The VLT Interferometer The Delay Lines consitute a most important element of the VLT Interferometer , cf. PR Photos 26a-e/00. At this moment, two Delay Lines are operational on site. A third system will be integrated early this year. The VLTI Delay Line is located in an underground tunnel that is 168 metres long and 8 metres wide. This configuration has been designed to accommodate up to eight Delay Lines, including their transfer optics in an ideal environment: stable temperature, high degree of cleanliness, low levels of straylight, low air turbulence. The positions of the Delay Line carriages are computed to adjust the Optical Path Lengths requested for the fringe pattern observation. The positions are controlled in real time by a laser metrology system, specially developed for this purpose. The position precision is about 20 nm (1 nm = 10 -9 m, or 1 millionth of a millimetre) over a distance of 120 metres. The maximum velocity is 0.50 m/s in position mode and maximum 0.05 m/s in operation. The system is designed for 25 year of operation and to survive earthquake up to 8.6 magnitude on the Richter scale. The VLTI Delay Line is a three-year project, carried out by ESO in collaboration with Dutch Space Holdings (formerly Fokker Space) and TPD-TNO . VLTI Delay Lines (December 2000) - ESO PR Video Clip 02b/01 [MPEG - 3.6Mb] ESO PR Video Clip 02b/01 "VLTI Delay Lines (December 2000)" (2000 frames/1:20 min) [MPEG Video+Audio; 160x120 pix; 3.6Mb] [MPEG Video+Audio; 320x240 pix; 13.7 Mb] [RealMedia; streaming; 34kps] [RealMedia; streaming; 200kps] ESO Video Clip 02b/00 shows the Delay Lines of the VLT Interferometer facility at Paranal during tests. One of the carriages is moving on 66-metre long rectified rails, driven by a linear motor. The carriage is equipped with three wheels in order to preserve high guidance accuracy. Another important element is the Cat's Eye that reflects the light from the telescope to the VLT instrumentation. This optical system is made of aluminium (including the mirrors) to avoid thermo-mechanical problems. ESO PR Photo 04e/01 ESO PR Photo 04e/01 [Preview - JPEG: 400 x 402 pix - 62k] [Normal - JPEG: 800 x 804 pix - 544k] [Hires - JPEG: 3000 x 3016 pix - 6.2M] Caption : PR Photo 04e/01 shows one of the 30 "stations" for the movable 1.8-m Auxiliary Telescopes. When one of these telescopes is positioned ("parked") on top of it, The light will be guided through the hole towards the Interferometric Tunnel and the Delay Lines. ESO PR Photo 04f/01 ESO PR Photo 04f/01 [Preview - JPEG: 568 x 400 pix - 96k] [Normal - JPEG: 1136 x 800 pix - 840k] [Hires - JPEG: 3000 x 2112 pix - 4.6M] PR Photo 04f/01 shows a general view of the Interferometric Tunnel and the Delay Lines. ESO PR Photo 04g/01 ESO PR Photo 04g/01 [Preview - JPEG: 406 x 400 pix - 62k] [Normal - JPEG: 812 x 800 pix - 448k] [Hires - JPEG: 3000 x 2956 pix - 5.5M] PR Photo 04g/01 shows one of the Delay Line carriages in parking position. The "NTT Peak" The "NTT Peak" is a mountain top located about 2 km to the north of Paranal. It received this name when ESO considered to move the 3.58-m New Technology Telescope from La Silla to this peak. The possibility of installing the 4-m VISTA telescope (cf. PR 03/00 ) on this peak is now being discussed. ESO PR Photo 04h/01 ESO PR Photo 04h/01 [Preview - JPEG: 630 x 400 pix - 89k] [Normal - JPEG: 1259 x 800 pix - 1.1M] [Hires - JPEG: 3000 x 1907 pix - 5.2M] PR Photo 04h/01 shows the view from the "NTT Peak" towards south, vith the Paranal mountain and the VLT enclosures in the background. ESO PR Photo 04i/01 ESO PR Photo 04i/01 [Preview - JPEG: 516 x 400 pix - 50k] [Normal - JPEG: 1031 x 800 pix - 664k] [Hires - JPEG: 3000 x 2328 pix - 6.0M] PR Photo 04i/01 is a view towards the "NTT Peak" from the top of the Paranal mountain. The access road and the concrete pillar that was used to support a site testing telescope at the top of this peak are seen This is the caption to ESO PR Photos 04a-1/01 and PR Video Clips 02a-b/01 . They may be reproduced, if credit is given to the European Southern Observatory. The ESO PR Video Clips service to visitors to the ESO website provides "animated" illustrations of the ongoing work and events at the European Southern Observatory. The most recent clip was: ESO PR Video Clip 01/01 about the Physics On Stage Festival (11 January 2001) . Information is also available on the web about other ESO videos.

Topological Acoustic Delay Line

NASA Astrophysics Data System (ADS)

Zhang, Zhiwang; Tian, Ye; Cheng, Ying; Wei, Qi; Liu, Xiaojun; Christensen, Johan

2018-03-01

Topological protected wave engineering in artificially structured media is at the frontier of ongoing metamaterials research that is inspired by quantum mechanics. Acoustic analogues of electronic topological insulators have recently led to a wealth of new opportunities in manipulating sound propagation with strikingly unconventional acoustic edge modes immune to backscattering. Earlier fabrications of topological insulators are characterized by an unreconfigurable geometry and a very narrow frequency response, which severely hinders the exploration and design of useful devices. Here we establish topologically protected sound in reconfigurable phononic crystals that can be switched on and off simply by rotating its three-legged "atoms" without altering the lattice structure. In particular, we engineer robust phase delay defects that take advantage of the ultrabroadband reflection-free sound propagation. Such topological delay lines serve as a paradigm in compact acoustic devices, interconnects, and electroacoustic integrated circuits.

RF tuning element

NASA Technical Reports Server (NTRS)

McGrath, William R. (Inventor); Lubecke, Victor M. (Inventor)

1992-01-01

A device for tuning a circuit includes a substrate, a transmission line on the substrate that includes first and second conductors coupled to a circuit to be tuned, and a movable short-circuit for varying the impedance the transmission line presents to the circuit to be tuned. The movable short-circuit includes a dielectric layer disposed atop the transmission line and a distributed shorting element in the form of a conductive member that is configured to be slid along at least a portion of the transmission line atop the dielectric layer. The conductive member is configured to span the first and second conductors of the transmission line and to define at least a first opening that spans the two conductors so that the conductive member includes first and second sections separated by the first opening. The first and second sections of the conductive member combine with the first and second conductors of the transmission line to form first and second low impedance sections of transmission line, and the opening combines with the first and second conductors of the transmission line and the dielectric layer to form a first high impedance section of transmission line intermediate the first and second low impedance sections. Each of the first low impedance section and the first high impedance section have a length along the transmission line of approximately one-quarter wavelength, thus providing a periodic variation of transmission line impedance. That enhances reflection of rf power.

PID Controller Settings Based on a Transient Response Experiment

ERIC Educational Resources Information Center

Silva, Carlos M.; Lito, Patricia F.; Neves, Patricia S.; Da Silva, Francisco A.

2008-01-01

An experimental work on controller tuning for chemical engineering undergraduate students is proposed using a small heat exchange unit. Based upon process reaction curves in open-loop configuration, system gain and time constant are determined for first order model with time delay with excellent accuracy. Afterwards students calculate PID…

Pupil engineering for a confocal reflectance line-scanning microscope

NASA Astrophysics Data System (ADS)

Patel, Yogesh G.; Rajadhyaksha, Milind; DiMarzio, Charles A.

2011-03-01

Confocal reflectance microscopy may enable screening and diagnosis of skin cancers noninvasively and in real-time, as an adjunct to biopsy and pathology. Current confocal point-scanning systems are large, complex, and expensive. A confocal line-scanning microscope, utilizing a of linear array detector can be simpler, smaller, less expensive, and may accelerate the translation of confocal microscopy in clinical and surgical dermatology. A line scanner may be implemented with a divided-pupil, half used for transmission and half for detection, or with a full-pupil using a beamsplitter. The premise is that a confocal line-scanner with either a divided-pupil or a full-pupil will provide high resolution and optical sectioning that would be competitive to that of the standard confocal point-scanner. We have developed a confocal line-scanner that combines both divided-pupil and full-pupil configurations. This combined-pupil prototype is being evaluated to determine the advantages and limitations of each configuration for imaging skin, and comparison of performance to that of commercially available standard confocal point-scanning microscopes. With the combined configuration, experimental evaluation of line spread functions (LSFs), contrast, signal-to-noise ratio, and imaging performance is in progress under identical optical and skin conditions. Experimental comparisons between divided-pupil and full-pupil LSFs will be used to determine imaging performance. Both results will be compared to theoretical calculations using our previously reported Fourier analysis model and to the confocal point spread function (PSF). These results may lead to a simpler class of confocal reflectance scanning microscopes for clinical and surgical dermatology.

Compact and low-cost THz QTDS system.

PubMed

Probst, Thorsten; Rehn, Arno; Koch, Martin

2015-08-24

We present a terahertz quasi time domain spectroscopy (QTDS) system setup which is improved regarding cost and compactness. The diode laser is mounted directly onto the optical delay line, making the optical setup more compact. The system is operated using a Raspberry Pi and an additional sound card. This combination replaces the desktop/laptop computer, the lock-in-amplifier, the stage controller and the signal generator. We examined not only a commercially available stepper motor driven delay line, but also the repurposed internal mechanics from a DVD drive. We characterize the performance of the new system concept.

Break-before-make CMOS inverter for power-efficient delay implementation.

PubMed

Puhan, Janez; Raič, Dušan; Tuma, Tadej; Bűrmen, Árpád

2014-01-01

A modified static CMOS inverter with two inputs and two outputs is proposed to reduce short-circuit current in order to increment delay and reduce power overhead where slow operation is required. The circuit is based on bidirectional delay element connected in series with the PMOS and NMOS switching transistors. It provides differences in the dynamic response so that the direct-path current in the next stage is reduced. The switching transistors are never ON at the same time. Characteristics of various delay element implementations are presented and verified by circuit simulations. Global optimization procedure is used to obtain the most power-efficient transistor sizing. The performance of the modified CMOS inverter chain is compared to standard implementation for various delays. The energy (charge) per delay is reduced up to 40%. The use of the proposed delay element is demonstrated by implementing a low-power delay line and a leading-edge detector cell.

Break-before-Make CMOS Inverter for Power-Efficient Delay Implementation

PubMed Central

Raič, Dušan

2014-01-01

A modified static CMOS inverter with two inputs and two outputs is proposed to reduce short-circuit current in order to increment delay and reduce power overhead where slow operation is required. The circuit is based on bidirectional delay element connected in series with the PMOS and NMOS switching transistors. It provides differences in the dynamic response so that the direct-path current in the next stage is reduced. The switching transistors are never ON at the same time. Characteristics of various delay element implementations are presented and verified by circuit simulations. Global optimization procedure is used to obtain the most power-efficient transistor sizing. The performance of the modified CMOS inverter chain is compared to standard implementation for various delays. The energy (charge) per delay is reduced up to 40%. The use of the proposed delay element is demonstrated by implementing a low-power delay line and a leading-edge detector cell. PMID:25538951

BPTAP: A New Approach to IP over DTN

NASA Technical Reports Server (NTRS)

Tsao, Philip; Nguyen, Sam

2012-01-01

Traditional Internet protocols have been widely deployed for a variety of applications. However such protocols generally perform poorly in situations in which, round trip delays are very large (interplanetary distances) or . persistent connectivity is not always available (widely dispersed MANET). Delay/Disruption Tolerant Network (DTN) technology was invented to address these issues: (1) . Relay nodes "take custody" of blocks of network traffic on a hop-by -hop basis and retransmit them in cases of expected or unexpected link outage (2) Bundle lifetime may be configured for long round trip light times. BPTAP is novel by encapsulating Ethernet frames in BP

Performances of a date dissemination code on telephone lines using commercial modems

NASA Technical Reports Server (NTRS)

Cordara, F.; Pettiti, V.; Quasso, R.; Rubiola, E.

1993-01-01

A coded time/date information dissemination system (CTD), based on telephone lines and commercial modems, is now in its experimental phase in Italy at IEN. This service, born from a cooperation with other metrological laboratories (TUG, Austria, SNT, Sweden, VSL, The Netherlands), represents an attempt towards an European standardization. Some results of an experimental analysis in which a few modems were tested, both in laboratory conditions and connected to the telephone network, in order to evaluate the timing capability of the system are given. When the system is used in a one-way mode, in many practical cases the modems delay turns out to be the main factor which limits the accuracy, even more than the telephone line delays. If the two-way mode is used, the modems asymmetry, i.e., the delay difference between transmission and reception, is almost always the most important source of uncertainty, provided the link is not including a space segment. Comparing the widely used V.22 modems to the old V.21 ones, the latters turn out to be better both in delay time (30-100 ms V.22, and 7-15 ms V.21) and asymmetry (10-50 micro-s V.22, and 10 ms V.22). Time transfer accuracies of 10 micron-s (same turn) to 100 micro-s (long distance calls) were obtained in two-way mode with commercial V.21 modems.

A REVERBERATION-BASED BLACK HOLE MASS FOR MCG-06-30-15

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

Bentz, Misty C.; Crenshaw, D. Michael; Ou-Yang, Benjamin

2016-10-20

We present the results of a reverberation campaign targeting MGC-06-30-15. Spectrophotometric monitoring and broad-band photometric monitoring over the course of four months in spring 2012 allowed a determination of a time delay in the broad H β emission line of τ = 5.3 ± 1.8 days in the rest frame of the active galactic nucleus (AGN). Combined with the width of the variable portion of the emission line, we determine a black hole mass of M {sub BH} = (1.6 ± 0.4) × 10{sup 6} M {sub ⊙}. Both the H β time delay and the black hole mass aremore » in good agreement with expectations from the R {sub BLR}– L and M {sub BH}– σ {sub ⋆} relationships for other reverberation-mapped AGNs. The H β time delay is also in good agreement with the relationship between H β and broad-band near-IR delays, in which the effective size of the broad-line region is ∼4–5 times smaller than the inner edge of the dust torus. Additionally, the reverberation-based mass is in good agreement with estimates from the scaling relationship of the break in the X-ray power spectral density, and with constraints based on stellar kinematics derived from integral field spectroscopy of the inner ∼0.5 kpc of the galaxy.« less

Laser-induced periodic surface structures on 6H-SiC single crystals using temporally delayed femtosecond laser double-pulse trains

NASA Astrophysics Data System (ADS)

Song, Juan; Tao, Wenjun; Song, Hui; Gong, Min; Ma, Guohong; Dai, Ye; Zhao, Quanzhong; Qiu, Jianrong

2016-04-01

In this paper, a time-delay-adjustable double-pulse train with 800-nm wavelength, 200-fs pulse duration and a repetition rate of 1 kHz, produced by a collinear two-beam optical system like a Mach-Zehnder interferometer, was employed for irradiation of 6H-SiC crystal. The dependence of the induced structures on time delay of double-pulse train for parallel-polarization configuration was studied. The results show that as the time delay of collinear parallel-polarization dual-pulse train increased, the induced near-subwavelength ripples (NSWRs) turn from irregular rippled pattern to regularly periodic pattern and have their grooves much deepened. The characteristics timescale for this transition is about 6.24 ps. Besides, the areas of NSWR were found to decay exponentially for time delay from 0 to 1.24 ps and then slowly increase for time delay from 1.24 to 14.24 ps. Analysis shows that multiphoton ionization effect, grating-assisted surface plasmon coupling effect, and timely intervene of second pulse in a certain physical stage experienced by 6H-SiC excited upon first pulse irradiation may contribute to the transition of morphology details.

A new experimental method for the accelerated characterization of composite materials

NASA Technical Reports Server (NTRS)

Brinson, H. F.; Morris, D. H.; Yeow, Y. T.

1978-01-01

A method which permits the prediction of long-term properties of graphite/epoxy laminates on the basis of short-term (15 min) laboratory tests is described. Demonstration of delayed viscoelastic fracture in one laminate configuration, and data on the time and temperature response of a matrix-dominated unidirectional laminate contributed to a characterization of the viscoelastic process in the graphite/epoxy composites. Master curves from short-term tests of certain laminate configurations can be employed to generate long-term master curves. In addition, analytical predictions from short-term results can be used to predict long-term (25-hour) laminate properties.

Acoustic Wave Propagation in Pressure Sense Lines

NASA Technical Reports Server (NTRS)

Vitarius, Patrick; Gregory, Don A.; Wiley, John; Korman, Valentin

2003-01-01

Sense lines are used in pressure measurements to passively transmit information from hostile environments to areas where transducers can be used. The transfer function of a sense line can be used to obtain information about the measured environment from the protected sensor. Several properties of this transfer function are examined, including frequency dependence, Helmholtz resonance, and time of flight delay.

A twofold quantum delayed-choice experiment in a superconducting circuit

PubMed Central

Liu, Ke; Xu, Yuan; Wang, Weiting; Zheng, Shi-Biao; Roy, Tanay; Kundu, Suman; Chand, Madhavi; Ranadive, Arpit; Vijay, Rajamani; Song, Yipu; Duan, Luming; Sun, Luyan

2017-01-01

Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system’s path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system’s behavior depends not only on the measuring device’s configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment. PMID:28508079

A twofold quantum delayed-choice experiment in a superconducting circuit.

PubMed

Liu, Ke; Xu, Yuan; Wang, Weiting; Zheng, Shi-Biao; Roy, Tanay; Kundu, Suman; Chand, Madhavi; Ranadive, Arpit; Vijay, Rajamani; Song, Yipu; Duan, Luming; Sun, Luyan

2017-05-01

Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system's path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system's behavior depends not only on the measuring device's configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment.

The WS transform for the Kuramoto model with distributed amplitudes, phase lag and time delay

NASA Astrophysics Data System (ADS)

Lohe, M. A.

2017-12-01

We apply the Watanabe-Strogatz (WS) transform to a generalized Kuramoto model with distributed parameters describing the amplitude of oscillation, phase lag, and time delay at each node of the system. The model has global coupling and identical frequencies, but allows for repulsive interactions at arbitrary nodes leading to conformist-contrarian phenomena together with variable amplitude and time-delay effects. We show how to determine the initial values of the WS system for any initial conditions for the Kuramoto system, and investigate the asymptotic behaviour of the WS variables. For the case of zero time delay the possible asymptotic configurations are determined by the sign of a single parameter μ which measures whether or not the attractive nodes dominate the repulsive nodes. If μ>0 the system completely synchronizes from general initial conditions, whereas if μ<0 one of two types of phase-locked synchronization occurs, depending on the initial values, while for μ=0 periodic solutions can occur. For the case of arbitrary non-uniform time delays we derive a stability condition for completely synchronized solutions.

Statistical Mechanics of the Delayed Reward-Based Learning with Node Perturbation

NASA Astrophysics Data System (ADS)

Hiroshi Saito,; Kentaro Katahira,; Kazuo Okanoya,; Masato Okada,

2010-06-01

In reward-based learning, reward is typically given with some delay after a behavior that causes the reward. In machine learning literature, the framework of the eligibility trace has been used as one of the solutions to handle the delayed reward in reinforcement learning. In recent studies, the eligibility trace is implied to be important for difficult neuroscience problem known as the “distal reward problem”. Node perturbation is one of the stochastic gradient methods from among many kinds of reinforcement learning implementations, and it searches the approximate gradient by introducing perturbation to a network. Since the stochastic gradient method does not require a objective function differential, it is expected to be able to account for the learning mechanism of a complex system, like a brain. We study the node perturbation with the eligibility trace as a specific example of delayed reward-based learning, and analyzed it using a statistical mechanics approach. As a result, we show the optimal time constant of the eligibility trace respect to the reward delay and the existence of unlearnable parameter configurations.

Ion current in a magnetic neutral region - Generation of an incipient magnetopause

NASA Technical Reports Server (NTRS)

Whipple, E. C.; Silevitch, M. B.

1982-01-01

The current contributed by ions trapped in the vicinity of a magnetic X line is calculated. The three dimensional configuration of the neutral region is found to be critical in determining the current in that the escape mechanism and trapping times depend on the three-dimensional aspects. A trapping criterion is defined. In the neutral region the ions can gain substantial kinetic energy, and the current will change the X line configuration in such a way that there will be a positive feedback effect, rapidly forming an extended magnetopauselike structure for even very small incident plasma densities.

Simultaneous recording of mouse retinal ganglion cells during epiretinal or subretinal stimulation

PubMed Central

Sim, S.L.; Szalewski, R.J.; Johnson, L.J.; Akah, L.E.; Shoemaker, L.E.; Thoreson, W.B.; Margalit, E.

2015-01-01

We compared response patterns and electrical receptive fields (ERF) of retinal ganglion cells (RGCs) during epiretinal and subretinal electrical stimulation of isolated mouse retina. Retinas were stimulated with an array of 3200 independently controllable electrodes. Four response patterns were observed: a burst of activity immediately after stimulation (Type I cells, Vision Research (2008), 48, 1562–1568), delayed bursts beginning >25 ms after stimulation (Type II), a combination of both (Type III), and inhibition of ongoing spike activity. Type I responses were produced more often by epiretinal than subretinal stimulation whereas delayed and inhibitory responses were evoked more frequently by subretinal stimulation. Response latencies were significantly shorter with epiretinal than subretinal stimulation. These data suggest that subretinal stimulation is more effective at activating intraretinal circuits than epiretinal stimulation. There was no significant difference in charge threshold between subretinal and epiretinal configurations. ERFs were defined by the stimulating array surface area that successfully stimulated spikes in an RGC. ERFs were complex in shape, similar to receptive fields mapped with light. ERF areas were significantly smaller with subretinal than epiretinal stimulation. This may reflect the greater distance between stimulating electrodes and RGCs in the subretinal configuration. ERFs for immediate and delayed responses mapped within the same Type III cells differed in shape and size, consistent with different sites and mechanisms for generating these two response types. PMID:24863584

Time-resolved coherent Raman spectroscopy by high-speed pump-probe delay scanning.

PubMed

Domingue, S R; Winters, D G; Bartels, R A

2014-07-15

Using a spinning window pump-probe delay scanner, we demonstrate a means of acquiring time-resolved vibrational spectra at rates up to 700 Hz. The time-dependent phase shift accumulated by the probe pulse in the presence of a coherently vibrating sample gives rise to a Raman-induced frequency shifting readily detectable in a balanced detector. This rapid delay scanning system represents a 23-fold increase in averaging speed and is >10× faster than state-of-the-art voice coil delay lines. These advancements make pump-probe spectroscopy a more practical means of imaging complex media.

Risk of progression in macula-on rhegmatogenous retinal detachment.

PubMed

Callizo, Josep; Pfeiffer, Sebastian; Lahme, Eva; van Oterendorp, Christian; Khattab, Mohammed; Bemme, Sebastian; Kulanga, Miroslav; Hoerauf, Hans; Feltgen, Nicolas

2017-08-01

To identify factors that may lead to a rapid progression in macula-on rhegmatogenous retinal detachment (RRD), in particular, those that may lead to macular involvement. Observational, prospective, single-center study. Patients referred for surgery due to primary rhegmatogenous retinal detachment with the macula on between 2009 and 2013 were included. Relevant factors analyzed included age, time delay until surgery, lens status, myopia, the detachment's location and configuration as well as number, size and type of retinal breaks. Eyes underwent optical coherence tomography to detect macular detachment. A multivariate analysis was performed to investigate the effect of several factors in the progression of retinal detachment. A total of 116 eyes of 116 patients were included. Mean time delay between admission and surgery was 1.8 ± 1.4 days. Progression was observed in 19.8% of the eyes. Of those, 47.8% presented macular detachment. Ten of the 11 (90.9%) eyes presenting progression involving the macula also exhibited a bullous configuration, which was the only parameter that correlated significantly with detachment progression in patients with (p = 0.0036) and without (p = 0.0014) macular involvement. For the first time in a prospective trial, a bullous configuration was found to be a highly significant predictor for progression in macula-on detachments. Our data support prompt surgery in patients diagnosed with bullous macula-on RRD.

Benefit Assessment for Metroplex Tactical Runway Configuration Management (mTRCM) in a Simulated Environment

NASA Technical Reports Server (NTRS)

Phojanamongkolkij, Nipa; Oseguera-Lohr, Rosa M.; Lohr, Gary W.; Robbins, Steven W.; Fenbert, James W.; Hartman, Christopher L.

2015-01-01

The System-Oriented Runway Management (SORM) concept is a collection of capabilities focused on a more efficient use of runways while considering all of the factors that affect runway use. Tactical Runway Configuration Management (TRCM), one of the SORM capabilities, provides runway configuration and runway usage recommendations, and monitoring the active runway configuration for suitability given existing factors. This report focuses on the metroplex environment, with two or more proximate airports having arrival and departure operations that are highly interdependent. The myriad of factors that affect metroplex opeations require consideration in arriving at runway configurations that collectively best serve the system as a whole. To assess the metroplex TRCM (mTRCM) benefit, the performance metrics must be compared with the actual historical operations. The historical configuration schedules can be viewed as the schedules produced by subject matter experts (SMEs), and therefore are referred to as the SMEs' schedules. These schedules were obtained from the FAA's Aviation System Performance Metrics (ASPM) database; this is the most representative information regarding runway configuration selection by SMEs. This report focused on a benefit assessment of total delay, transit time, and throughput efficiency (TE) benefits using the mTRCM algorithm at representative volumes for today's traffic at the New York metroplex (N90).

Magneto-optical observation of twisted vortices in type-II superconductors

NASA Astrophysics Data System (ADS)

Indenbom, M. V.; van der Beek, C. J.; Berseth, V.; Benoit, W.; D'Anna, G.; Erb, A.; Walker, E.; Flükiger, R.

1997-02-01

When magnetic flux penetrates a type-II superconductor, it does so as quantized flux lines or vortex lines, so called because each is surrounded by a supercurrent vortex. Interactions between such vortices lead to a very rich and well characterized phenomenology for this 'mixed state'. But an outstanding question remains: are individual vortex lines 'strong', or can they easily be cut and made to pass through one another? The concept of vortex cutting was originally proposed to account for dissipation observed in superconducting wires oriented parallel to an applied magnetic field, where the vortex lines and transport current should be in a force-free configuration1-6. Previous experiments, however, have been unable to establish the vortex topology in the force-free configuration or the size of the energy barrier for vortex cutting. Here we report magneto-optical images of YBa2Cu3O7-δ samples in the force-free configuration which show that thousands of vortex lines can twist together to form highly stable structures. In some cases, these 'vortex twisters' interact with one another to produce wave-like dynamics. Our measurements also determine directly the current required to initiate vortex cutting, and show that it is much higher than that needed to overcome the pinning of vortices by material defects. This implies that thermodynamic phases of entangled vortices7-10 are intrinsically stable and may occupy a significant portion of the mixed-state phase diagram for type-II superconductors.

Phase mixing of Alfvén waves in axisymmetric non-reflective magnetic plasma configurations

NASA Astrophysics Data System (ADS)

Petrukhin, N. S.; Ruderman, M. S.; Shurgalina, E. G.

2018-02-01

We study damping of phase-mixed Alfvén waves propagating in non-reflective axisymmetric magnetic plasma configurations. We derive the general equation describing the attenuation of the Alfvén wave amplitude. Then we applied the general theory to a particular case with the exponentially divergent magnetic field lines. The condition that the configuration is non-reflective determines the variation of the plasma density along the magnetic field lines. The density profiles exponentially decreasing with the height are not among non-reflective density profiles. However, we managed to find non-reflective profiles that fairly well approximate exponentially decreasing density. We calculate the variation of the total wave energy flux with the height for various values of shear viscosity. We found that to have a substantial amount of wave energy dissipated at the lower corona, one needs to increase shear viscosity by seven orders of magnitude in comparison with the value given by the classical plasma theory. An important result that we obtained is that the efficiency of the wave damping strongly depends on the density variation with the height. The stronger the density decrease, the weaker the wave damping is. On the basis of this result, we suggested a physical explanation of the phenomenon of the enhanced wave damping in equilibrium configurations with exponentially diverging magnetic field lines.

Dynamic Stall of Finite Span Blades and its Control

NASA Astrophysics Data System (ADS)

Taylor, Keith; Leong, Chia; Amitay, Michael

2013-11-01

An experimental investigational study into a dynamically pitching s809 airfoil at a Reynolds number of 220,000 was conducted. Particle Image Velocimetry was employed to visualize and quantify the flow field around the airfoil. This investigation compares a 2-D configuration with 3-D configuration (i.e., a finite span blade). The difference in the flow field between these two configurations is explored, as the vibrations present in the 3-D configuration (due to the dynamic stall) may contribute to a different apparent flow field than classical results would suggest. In addition, a comparison between lift and drag coefficients, measured on the 2-D and 3-D configurations, is explored, demonstrating how time varying lift and drag forces oscillate at characteristic frequencies associated with the primary vibrational modes of the model. In addition, flow control is applied through the actuation of an array of synthetic jets located near the leading edge of the model, in order to effect changes in the flow field around the model, demonstrating how dynamic stall can be delayed or eliminated during dynamic conditions.

Submarine Construction (Unterseebootsbau)

DTIC Science & Technology

1972-08-01

PIPE FOR THE SNORKEL EXHAUST MAST 11 AIR EXIT (GENERALLY TO MAIN AIR INDUCTION LINE) 12 EXHAUST GAS INLET FROM EXHAUST GAS LINE SIDE VIEW (MAST...Electric Engine 76 Diesel Engines 79 Air Intake and Gas Exhaust Systems for the Diesel Engines 79 Diesel Fuel and Pressurized Water System 82...Lines of a Submarine ■. 31 Figure 6 - Lines of a Submersible 31 Figure 7 - Twin- Screw Stern Configurations 34 Figure 8 - Single- Screw Stern

Investigation of the line arrangement of 2D resistivity surveys for 3D inversion*

NASA Astrophysics Data System (ADS)

Inoue, Keisuke; Nakazato, Hiroomi; Takeuchi, Mutsuo; Sugimoto, Yoshihiro; Kim, Hee Joon; Yoshisako, Hiroshi; Konno, Michiaki; Shoda, Daisuke

2018-03-01

We have conducted numerical and field experiments to investigate the applicability of electrode configurations and line layouts commonly used for two-dimensional (2D) resistivity surveys to 3D inversion. We examined three kinds of electrode configurations and two types of line arrangements, for 16 resistivity models of a conductive body in a homogeneous half-space. The results of the numerical experiment revealed that the parallel-line arrangement was effective in identifying the approximate location of the conductive body. The orthogonal-line arrangement was optimal for identifying a target body near the line intersection. As a result, we propose that parallel lines are useful to highlight areas of particular interest where further detailed work with an intersecting line could be carried out. In the field experiment, 2D resistivity data were measured on a loam layer with a backfilled pit. The reconstructed resistivity image derived from parallel-line data showed a low-resistivity portion near the backfilled pit. When an orthogonal line was added to the parallel lines, the newly estimated location of the backfilled pit coincided well with the actual location. In a further field application, we collected several 2D resistivity datasets in the Nojima Fault area in Awaji Island. The 3D inversion of these datasets provided a resistivity distribution corresponding to the geological structure. In particular, the Nojima Fault was imaged as the western boundary of a low-resistivity belt, from only two orthogonal lines.

Context based configuration management system

NASA Technical Reports Server (NTRS)

Gurram, Mohana M. (Inventor); Maluf, David A. (Inventor); Mederos, Luis A. (Inventor); Gawdiak, Yuri O. (Inventor)

2010-01-01

A computer-based system for configuring and displaying information on changes in, and present status of, a collection of events associated with a project. Classes of icons for decision events, configurations and feedback mechanisms, and time lines (sequential and/or simultaneous) for related events are displayed. Metadata for each icon in each class is displayed by choosing and activating the corresponding icon. Access control (viewing, reading, writing, editing, deleting, etc.) is optionally imposed for metadata and other displayed information.

A Wedge Absorber Experiment at MICE

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

Neuffer, David; Mohayai, Tanaz; Rogers, Chris

2017-05-01

Emittance exchange mediated by wedge absorbers is required for longitudinal ionization cooling and for final transverse emittance minimization for a muon collider. A wedge absorber within the MICE beam line could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders, as well as configurations for low-energy muon sources. Parameters for this test are explored in simulation and possible experimental configurations with simulated results are presented.

Dynamic sample size detection in learning command line sequence for continuous authentication.

PubMed

Traore, Issa; Woungang, Isaac; Nakkabi, Youssef; Obaidat, Mohammad S; Ahmed, Ahmed Awad E; Khalilian, Bijan

2012-10-01

Continuous authentication (CA) consists of authenticating the user repetitively throughout a session with the goal of detecting and protecting against session hijacking attacks. While the accuracy of the detector is central to the success of CA, the detection delay or length of an individual authentication period is important as well since it is a measure of the window of vulnerability of the system. However, high accuracy and small detection delay are conflicting requirements that need to be balanced for optimum detection. In this paper, we propose the use of sequential sampling technique to achieve optimum detection by trading off adequately between detection delay and accuracy in the CA process. We illustrate our approach through CA based on user command line sequence and naïve Bayes classification scheme. Experimental evaluation using the Greenberg data set yields encouraging results consisting of a false acceptance rate (FAR) of 11.78% and a false rejection rate (FRR) of 1.33%, with an average command sequence length (i.e., detection delay) of 37 commands. When using the Schonlau (SEA) data set, we obtain FAR = 4.28% and FRR = 12%.

A counting-weighted calibration method for a field-programmable-gate-array-based time-to-digital converter

NASA Astrophysics Data System (ADS)

Chen, Yuan-Ho

2017-05-01

In this work, we propose a counting-weighted calibration method for field-programmable-gate-array (FPGA)-based time-to-digital converter (TDC) to provide non-linearity calibration for use in positron emission tomography (PET) scanners. To deal with the non-linearity in FPGA, we developed a counting-weighted delay line (CWD) to count the delay time of the delay cells in the TDC in order to reduce the differential non-linearity (DNL) values based on code density counts. The performance of the proposed CWD-TDC with regard to linearity far exceeds that of TDC with a traditional tapped delay line (TDL) architecture, without the need for nonlinearity calibration. When implemented in a Xilinx Vertix-5 FPGA device, the proposed CWD-TDC achieved time resolution of 60 ps with integral non-linearity (INL) and DNL of [-0.54, 0.24] and [-0.66, 0.65] least-significant-bit (LSB), respectively. This is a clear indication of the suitability of the proposed FPGA-based CWD-TDC for use in PET scanners.

Role of action potential configuration and the contribution of Ca2+ and K+ currents to isoprenaline-induced changes in canine ventricular cells

PubMed Central

Szentandrássy, N; Farkas, V; Bárándi, L; Hegyi, B; Ruzsnavszky, F; Horváth, B; Bányász, T; Magyar, J; Márton, I; Nánási, PP

2012-01-01

BACKGROUND AND PURPOSE Although isoprenaline (ISO) is known to activate several ion currents in mammalian myocardium, little is known about the role of action potential morphology in the ISO-induced changes in ion currents. Therefore, the effects of ISO on action potential configuration, L-type Ca2+ current (ICa), slow delayed rectifier K+ current (IKs) and fast delayed rectifier K+ current (IKr) were studied and compared in a frequency-dependent manner using canine isolated ventricular myocytes from various transmural locations. EXPERIMENTAL APPROACH Action potentials were recorded with conventional sharp microelectrodes; ion currents were measured using conventional and action potential voltage clamp techniques. KEY RESULTS In myocytes displaying a spike-and-dome action potential configuration (epicardial and midmyocardial cells), ISO caused reversible shortening of action potentials accompanied by elevation of the plateau. ISO-induced action potential shortening was absent in endocardial cells and in myocytes pretreated with 4-aminopyridine. Application of the IKr blocker E-4031 failed to modify the ISO effect, while action potentials were lengthened by ISO in the presence of the IKs blocker HMR-1556. Both action potential shortening and elevation of the plateau were prevented by pretreatment with the ICa blocker nisoldipine. Action potential voltage clamp experiments revealed a prominent slowly inactivating ICa followed by a rise in IKs, both currents increased with increasing the cycle length. CONCLUSIONS AND IMPLICATIONS The effect of ISO in canine ventricular cells depends critically on action potential configuration, and the ISO-induced activation of IKs– but not IKr– may be responsible for the observed shortening of action potentials. PMID:22563726

Role of action potential configuration and the contribution of C²⁺a and K⁺ currents to isoprenaline-induced changes in canine ventricular cells.

PubMed

Szentandrássy, N; Farkas, V; Bárándi, L; Hegyi, B; Ruzsnavszky, F; Horváth, B; Bányász, T; Magyar, J; Márton, I; Nánási, P P

2012-10-01

Although isoprenaline (ISO) is known to activate several ion currents in mammalian myocardium, little is known about the role of action potential morphology in the ISO-induced changes in ion currents. Therefore, the effects of ISO on action potential configuration, L-type Ca²⁺ current (I(Ca)), slow delayed rectifier K⁺ current (I(Ks)) and fast delayed rectifier K⁺ current (I(Kr)) were studied and compared in a frequency-dependent manner using canine isolated ventricular myocytes from various transmural locations. Action potentials were recorded with conventional sharp microelectrodes; ion currents were measured using conventional and action potential voltage clamp techniques. In myocytes displaying a spike-and-dome action potential configuration (epicardial and midmyocardial cells), ISO caused reversible shortening of action potentials accompanied by elevation of the plateau. ISO-induced action potential shortening was absent in endocardial cells and in myocytes pretreated with 4-aminopyridine. Application of the I(Kr) blocker E-4031 failed to modify the ISO effect, while action potentials were lengthened by ISO in the presence of the I(Ks) blocker HMR-1556. Both action potential shortening and elevation of the plateau were prevented by pretreatment with the I(Ca) blocker nisoldipine. Action potential voltage clamp experiments revealed a prominent slowly inactivating I(Ca) followed by a rise in I(Ks) , both currents increased with increasing the cycle length. The effect of ISO in canine ventricular cells depends critically on action potential configuration, and the ISO-induced activation of I(Ks) - but not I(Kr) - may be responsible for the observed shortening of action potentials. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

Dynamical Sequestration of the Moon-Forming Impactor in Co-Orbital Resonance with Earth

NASA Astrophysics Data System (ADS)

Kortenkamp, Stephen J.; Hartmann, William J.

2015-11-01

Recent concerns about the giant impact hypothesis for the origin of the moon, and an associated “isotope crisis” are assuaged if the impactor was a local object that formed near Earth and the impact occurred relatively late. We investigated a scenario that may meet these criteria, with the moon-forming impactor originating in 1:1 co-orbital resonance with Earth. Using N-body numerical simulations we explored the dynamical consequences of placing Mars-mass companions in various co-orbital configurations with a proto-Earth having 90% of its current mass. We modeled configurations that include the four terrestrial planets as well as configurations that also include the four giant planets. In both the 4- and 8-planet models we found that a single additional Mars-mass companion typically remains a stable co-orbital of Earth for the entire 250 million year (Myr) duration of our simulations (33 of 34 simulations). In an effort to destabilize such a system we carried out an additional 45 simulations that included a second Mars-mass co-orbital companion. Even with two Mars-mass companions sharing Earth’s orbit most of these models (28) also remained stable for the entire 250 Myr duration of the simulations. Of the 17 two-companion models that eventually became unstable 12 impacts were observed between Earth and an escaping co-orbital companion. The average delay we observed for an impact of a Mars-mass companion with Earth was 101 Myr, and the longest delay was 221 Myr. Several of the stable simulations involved unusual 3-planet co-orbital configurations that could exhibit interesting observational signatures in plantetary transit surveys.

Ground-Based GPS Sensing of Azimuthal Variations in Precipitable Water Vapor

NASA Technical Reports Server (NTRS)

Kroger, P. M.; Bar-Sever, Y. E.

1997-01-01

Current models for troposphere delay employed by GPS software packages map the total zenith delay to the line-of-sight delay of the individual satellite-receiver link under the assumption of azimuthal homogeneity. This could be a poor approximation for many sites, in particular, those located at an ocean front or next to a mountain range. We have modified the GIPSY-OASIS II software package to include a simple non-symmetric mapping function (MacMillan, 1995) which introduces two new parameters.

STS-34 Cargo Configuration drawing with payload bay location of Galileo/IUS

NASA Technical Reports Server (NTRS)

1989-01-01

Visual aid entitled NATIONAL STS PROGRAM STS-34 CARGO CONFIGURATION is a line drawing of Atlantis, Orbiter Vehicle (OV) 104, orbiting the Earth with its payload bay doors (PLBDs) open. A label identifies the Galileo spacecraft on an inertial upper stage (IUS) and its location in the payload bay (PLB).

Characterization of Cladosporols from the Marine Algal-Derived Endophytic Fungus Cladosporium cladosporioides EN-399 and Configurational Revision of the Previously Reported Cladosporol Derivatives.

PubMed

Li, Hong-Lei; Li, Xiao-Ming; Mándi, Attila; Antus, Sándor; Li, Xin; Zhang, Peng; Liu, Yang; Kurtán, Tibor; Wang, Bin-Gui

2017-10-06

Four new cladosporol derivatives, cladosporols F-I (1-4), the known cladosporol C (5), and its new epimer, cladosporol J (6), were isolated and identified from the marine algal-derived endophytic fungus Cladosporium cladosporioides EN-399. Their structures were determined by detailed interpretation of NMR and MS data, and the absolute configurations were established on the basis of TDDFT-ECD and OR calculations. The configurational assignment of cladosporols F (1) and G (2) showed that the previously reported absolute configuration of cladosporol A and all the related cladosporols need to be revised from (4'R) to (4'S). Compounds 1-6 showed antibacterial activity against Escherichia coli, Micrococcus luteus, and Vibrio harveyi with MIC values ranging from 4 to 128 μg/mL. Compound 3 showed significant cytotoxicity against A549, Huh7, and LM3 cell lines with IC 50 values of 5.0, 1.0, and 4.1 μM, respectively, and compound 5 showed activity against H446 cell line with IC 50 value of 4.0 μM.

40 CFR 90.1003 - Prohibited acts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... inventory of uncertified engines or Phase 1 engines beyond normal business practices to avoid or delay... model year in which less stringent standards under this part were in effect, shall not be subject to the... respects to a certified configuration of the same or later model year as the engine being replaced. (v) In...

78 FR 25846 - Special Conditions: Airbus, Model A340-600 Series Airplanes; Lower Deck Crew Rest Compartments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-03

... significantly delay issuance of the design approval and thus delivery of the affected aircraft. In addition, the... specific portion of the special conditions, explain the reason for any recommended change, and include... compartment configuration that affect crew member emergency egress or any other procedures affecting the...

D-A-D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies.

PubMed

Gan, Lin; Li, Xianglong; Cai, Xinyi; Liu, Kunkun; Li, Wei; Su, Shi-Jian

2018-01-01

The design of orange-light emitting, thermally activated, delayed fluorescence (TADF) materials is necessary and important for the development and application of organic light-emitting diodes (OLEDs). Herein, two donor-acceptor-donor (D-A-D)-type orange TADF materials based on fluorenone and acridine, namely 2,7-bis(9,9-dimethylacridin-10(9 H )-yl)-9 H -fluoren-9-one (27DACRFT, 1 ) and 3,6-bis(9,9-dimethylacridin-10(9 H )-yl)-9 H -fluoren-9-one (36DACRFT, 2 ), were successfully synthetized and characterized. The studies on their structure-property relationship show that the different configurations have a serious effect on the photoluminescence and electroluminescence performance according to the change in singlet-triplet splitting energy (Δ E ST ) and excited state geometry. This indicates that a better configuration design can reduce internal conversion and improve triplet exciton utilization of TADF materials. Importantly, OLEDs based on 2 exhibited a maximum external quantum efficiency of 8.9%, which is higher than the theoretical efficiency of the OLEDs based on conventional fluorescent materials.

Feed network and electromagnetic radiation source

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

Ardavan, Arzhang; Singleton, John; Linehan, Kevin E.

An antenna may include a volume polarization current radiator and a feed network. The volume polarization current radiator, includes a dielectric solid (such as a dielectric strip), and a plurality of closely-spaced excitation elements (24), each excitation element (24) being configured to induce a volume polarization current distribution in the dielectric solid proximate to the excitation element when a voltage is applied to the excitation element. The feed network is coupled to the volume polarization current radiator. The feed network also includes a plurality of passive power divider elements (32) and a plurality of passive delay elements (d1-d6) coupling themore » first port (30) and the plurality of second ports (108, 109, 164), the plurality of power divider elements (32) and the plurality of phase delay elements (d1-d6) being configured such that a radio-frequency signal that is applied to the first port (30) experiences a progressive change of phase as it is coupled to the plurality of second ports (108, 109, 164) so as to cause the volume polarization current distribution to propagate along the dielectric solid.« less

Flight test experience with pilot-induced-oscillation suppressor filters

NASA Technical Reports Server (NTRS)

Shafer, M. F.; Smith, R. E.; Stewart, J. F.; Bailey, R. E.

1983-01-01

Digital flight control systems are popular for their flexibility, reliability, and power; however, their use sometimes results in deficient handling qualities, including pilot-induced oscillation (PIO), which can require extensive redesign of the control system. When redesign is not immediately possible, temporary solutions, such as the PIO suppression (PIOS) filter developed for the Space Shuttle, have been proposed. To determine the effectiveness of such PIOS filters on more conventional, high-performance aircraft, three experiments were performed using the NASA F-8 digital fly-by-wire and USAF/Calspan NT-33 variable-stability aircraft. Two types of PIOS filters were evaluated, using high-gain, precision tasks (close formation, probe-and-drogue refueling, and precision touch-and-go landing) with a time delay or a first-order lag added to make the aircraft prone to PIO. Various configurations of the PIOS filter were evaluated in the flight programs, and most of the PIOS filter configurations reduced the occurrence of PIOs and improved the handling qualities of the PIO-prone aircraft. These experiments also confirmed the influence of high-gain tasks and excessive control system time delay in evoking pilot-induced oscillations.

Flight test experience with pilot-induced-oscillation suppression filters

NASA Technical Reports Server (NTRS)

Shafer, M. F.; Smith, R. E.; Stewart, J. F.; Bailey, R. E.

1984-01-01

Digital flight control systems are popular for their flexibility, reliability, and power; however, their use sometimes results in deficient handling qualities, including pilot-induced oscillation (PIO), which can require extensive redesign of the control system. When redesign is not immediately possible, temporary solutions, such as the PIO suppression (PIOS) filter developed for the Space Shuttle, have been proposed. To determine the effectiveness of such PIOS filters on more conventional, high-performance aircraft, three experiments were performed using the NASA F-8 digital fly-by-wire and USAF/Calspan NT-33 variable-stability aircraft. Two types of PIOS filters were evaluated, using high-gain, precision tasks (close formation, probe-and-drogue refueling, and precision touch-and-go landing) with a time delay or a first-order lag added to make the aircraft prone to PIO. Various configurations of the PIOS filter were evaluated in the flight programs, and most of the PIOS filter configurations reduced the occurrence of PIOs and improved the handling qualities of the PIO-prone aircraft. These experiments also confirmed the influence of high-gain tasks and excessive control system time delay in evoking pilot-induced oscillations.

The role of features and configural processing in face-race classification

PubMed Central

Zhao, Lun; Bentin, Shlomo

2011-01-01

We explored perceptual factors that might account for the other-race classification advantage (ORCA) in classifying faces by race. Testing Chinese participants in China and Israeli participants in Israel we show that: (a) The distinction between Chinese and Israeli faces is highly accurate even on the basis of isolated eyes or faces with eyes concealed, but full faces are categorized faster. (b) The ORCA is similarly robust for full faces and for face parts. (c) The ORCA was larger when the configuration of the inner-face components was distorted, reflecting delayed categorization of own-race distorted faces relative to own-race normally configured faces but no conspicuous distortion effect on other-race faces. These data demonstrate that perceptual factors can account for the ORCA independently of social bias. We suggest that one source of the ORCA in race categorization is the configural analysis applied by default while processing own-race but not other-race faces. PMID:22008980

Broadband optical frequency comb generator based on driving N-cascaded modulators by Gaussian-shaped waveform

NASA Astrophysics Data System (ADS)

Hmood, Jassim K.; Harun, Sulaiman W.

2018-05-01

A new approach for realizing a wideband optical frequency comb (OFC) generator based on driving cascaded modulators by a Gaussian-shaped waveform, is proposed and numerically demonstrated. The setup includes N-cascaded MZMs, a single Gaussian-shaped waveform generator, and N-1 electrical time delayer. The first MZM is driven directly by a Gaussian-shaped waveform, while delayed replicas of the Gaussian-shaped waveform drive the other MZMs. An analytical model that describes the proposed OFC generator is provided to study the effect of number and chirp factor of cascaded MZM as well as pulse width on output spectrum. Optical frequency combs at frequency spacing of 1 GHz are generated by applying Gaussian-shaped waveform at pulse widths ranging from 200 to 400 ps. Our results reveal that, the number of comb lines is inversely proportional to the pulse width and directly proportional to both number and chirp factor of cascaded MZMs. At pulse width of 200 ps and chirp factor of 4, 67 frequency lines can be measured at output spectrum of two-cascaded MZMs setup. Whereas, increasing the number of cascaded stages to 3, 4, and 5, the optical spectra counts 89, 109 and 123 frequency lines; respectively. When the delay time is optimized, 61 comb lines can be achieved with power fluctuations of less than 1 dB for five-cascaded MZMs setup.

Memory for Spatial Locations in a Patient with Near Space Neglect and Optic Ataxia: Involvement of the Occipitotemporal Stream

PubMed Central

Chieffi, Sergio; Messina, Giovanni; Messina, Antonietta; Villano, Ines; Monda, Vincenzo; Ambra, Ferdinando Ivano; Garofalo, Elisabetta; Romano, Felice; Mollica, Maria Pina; Monda, Marcellino; Iavarone, Alessandro

2017-01-01

Previous studies suggested that the occipitoparietal stream orients attention toward the near/lower space and is involved in immediate reaching, whereas the occipitotemporal stream orients attention toward the far/upper space and is involved in delayed reaching. In the present study, we investigated the role of the occipitotemporal stream in attention orienting and delayed reaching in a patient (GP) with bilateral damage to the occipitoparietal areas and optic ataxia. GP and healthy controls took part in three experiments. In the experiment 1, the participants bisected lines oriented along radial, vertical, and horizontal axes. GP bisected radial lines farther, and vertical lines more above, than the controls, consistent with an attentional bias toward the far/upper space and near/lower space neglect. The experiment 2 consisted of two tasks: (1) an immediate reaching task, in which GP reached target locations under visual control and (2) a delayed visual reaching task, in which GP and controls were asked to reach remembered target locations visually presented. We measured constant and variable distance and direction errors. In immediate reaching task, GP accurately reached target locations. In delayed reaching task, GP overshot remembered target locations, whereas the controls undershot them. Furthermore, variable errors were greater in GP than in the controls. In the experiment 3, GP and controls performed a delayed proprioceptive reaching task. Constant reaching errors did not differ between GP and the controls. However, variable direction errors were greater in GP than in the controls. We suggest that the occipitoparietal damage, and the relatively intact occipitotemporal region, produced in GP an attentional orienting bias toward the far/upper space (experiment 1). In turns, the attentional bias selectively shifted toward the far space remembered visual (experiment 2), but not proprioceptive (experiment 3), target locations. As a whole, these findings further support the hypothesis of an involvement of the occipitotemporal stream in delayed reaching. Furthermore, the observation that in both delayed reaching tasks the variable errors were greater in GP than in the controls suggested that in optic ataxia is present not only a visuo- but also a proprioceptivo-motor integration deficit. PMID:28620345

EBCO Technologies TR Cyclotrons, Dynamics, Equipment, and Applications

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

Johnson, R.R.; Univ British Columbia; Erdman, K. L.

2003-08-26

The Ebco Technologies TR cyclotrons have a common parent in the 500 MeV negative ion cyclotron at TRIUMF in Vancouver. As such, the TR cyclotrons have features that can be adapted for specific application. The cyclotron design is modularized into ion source and injection system, central region and then extraction. The cyclotron ion source is configured for cyclotron beam currents ranging from 50 microAmps to 2 milliAmps. The injection line can be operated in either continuous (CW) or in pulsed mode. The center region of the cyclotron is configured to match the ion source configuration. The extracted beams are directedmore » either to a local target station or to beam lines and thence to target stations. There has been development both in solid, liquid and gas targets. There has been development in radioisotope handling techniques, target material recovery and radiochemical synthesis.« less

Spectrum and energy levels of six-times ionized yttrium (Y VII)

NASA Astrophysics Data System (ADS)

Reader, Joseph

2018-03-01

The spectrum of six-times ionized yttrium, Y VII, was photographed with a sliding-spark discharge on 10.7 m normal- and grazing-incidence spectrographs. The region of observation was 157-824 Å. The observations extend the known configurations 4s24p3, 4s4p4, 4p5, 4s24p25s, 4s24p26s to the nearly complete 4s24p24d configuration. Our results for 4s24p24d significantly revise results of Rahimullah et al (1978 Phys. Scr. 18 96); Ateqad et al (1984 J. Phys. B: At. Mol. Phys. 17 4617). A total of 168 lines and 56 energy levels are now known for this ion. The observed configurations were interpreted with Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels. Transition probabilities for all classified lines were calculated with the fitted parameters.

The Sojourn Time in a Three Node, Acyclic, Jackson Queueing Network.

DTIC Science & Technology

1982-01-27

Effect of Intermediate Storage on Production Lines with Dependent Machines, Robert D. Foley and Petcharat Chansaenwilai 8015 Some Conditions for the...Queues, Robert D. Foley 8105 Reversibility of Production Lines with Dependent Machines, Petcharat Chansaenwilai 1 8106 Queues with Delayed Feedback, Robert

Overload protection for switching regulators

NASA Technical Reports Server (NTRS)

Lachochi, E.

1980-01-01

Circuit protects all output lines of switching regulator against overloads without requiring current sensors on every line. If overload is sensed, device short circuits bias on switching transistor so that power is rapidly cut off from loads. Circuit also includes delay network to inhibit erroneous operation during startup.

Identification of soft drinks using MEMS-IDT microsensors

NASA Astrophysics Data System (ADS)

Abraham, Jose K.; Karjathkar, Sonal; Jacesko, Stefany; Varadan, Vijay K.; Gardner, Julian W.

2005-05-01

Development of a taste sensor with high sensitivity, stability and selectivity is highly desirable for the food and beverage industries. The main goal of a taste sensor is to reproduce five kinds of senses of humans, which is quite difficult. The importance of knowing quality of beverages and drinking water has been recognized as a result of increase in concern in environmental pollution issues. However, no accurate measuring system appropriate for quality evaluation of beverages is available. A highly sensitive microsensor using horizontally polarized Surface Acoustic Waves (SH-SAW) for the detection and identification of soft drinks is presented in this paper. Different soft drinks were tested using this sensor and the results which could distinguish between two popular soft drinks like Pepsi and Coca cola is presented in this paper. The SH-SAW microsensors are fabricated on 36°-rotated Y cut X propagating LiTaO3 (36YX.LT) substrate. This design consists of a dual delay line configuration in which one line is free and other one is metallized and shielded. Due to high electromechanical coupling of 36YX.LT, it could detect difference in electrical properties and hence to distinguish different soft drinks. Measured electrical characteristics of these soft drinks at X-band frequency using free space system show distinguishable results. It is clear from these results that the microsensor based on 36YX.LT is an effective liquid identification system for quantifying human sensory expressions.

DFB laser - External modulator fiber optic delay line for radar applications

NASA Astrophysics Data System (ADS)

Newberg, I. L.; Gee, C. M.; Thurmond, G. D.; Yen, H. W.

1989-09-01

A new application of a long fiber-optic delay line as a radar repeater in a radar test set is described. The experimental 31.6-kilometer fiber-optic link includes an external modulator operating with a distributed-feedback laser and low-loss single-mode fiber matched to the laser wavelength to obtain low dispersion for achieving large bandwidth-length performance. The successful tests, in which pulse compression peak sidelobe measurements are used to confirm the link RF phase linearity and SNR performance, show that fiber-optic links can meet the stringent phase and noise requirements of modern radars at high microwave frequencies.

Displacement sensors using soft magnetostrictive alloys

NASA Astrophysics Data System (ADS)

Hristoforou, E.; Reilly, R. E.

1994-09-01

We report results on the response of a family of displacement sensors, which are based on the magentostrictive delay line (MDL) technique, using current conductors orthogonal to the MDL. Such sensing technique is based on the change of the magnetic circuit at the acoustic stress point of origin due to the displacement of a soft magnetic material above it. Integrated arrays of sensors can be obtained due to the acoustic delay line technique and they can be used as tactile arrays, digitizers or devices for medical applications (gait analysis etc.), while absence of hysteresis and low cost of manufacturing make them competent in this sector of sensor market.

Rippled disc electrostatic generator/motor configurations utilizing magnetic insulation

DOEpatents

Post, Richard F

2017-04-04

Electrostatic generators/motors designs are provided that generally may include a first rippled stator centered about a longitudinal axis; a second rippled stator centered about the axis, a first rippled rotor centered about the axis and located between the first rippled stator and the second rippled stator. A magnetic field having field lines about parallel with the average plane of at least one of the first rippled stator or the second rippled stator is provided with either a Halbach array configuration or a conductor array configuration.

Debonding of Stitched Composite Joints: Testing and Analysis

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1999-01-01

The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and analytical study. The experimental study was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation ofthe debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The strain energy release rates at the debond front were calculated using a finite element-based technique. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches effectively reduced mode I to zero, but had less of an effect on modes II and III.

Forbidden line emission from highly ionized atoms in tokamak plasmas

NASA Technical Reports Server (NTRS)

Feldman, U.; Doschek, G. A.; Bhatia, A. K.

1982-01-01

Considerable interest in the observation of forbidden spectral lines from highly ionized atoms in tokamak plasmas is related to the significance of such observations for plasma diagnostic applications. Atomic data for the elements Ti Cr, Mn, Fe, Ni, and Kr have been published by Feldman et al. (1980) and Bhatia et al. (1980). The present investigation is concerned with collisional excitation rate coefficients and radiative decay rates, which are interpolated for ions of elements between calcium, and krypton and for levels of the 2s2 2pk, 2s 2p(k+1), and 2p(k+2) configurations, and for the O I, N I, C I, B I, and Be I isoelectronic sequences. The provided interpolated atomic data can be employed to calculate level populations and relative line intensities for ions of the considered sequences, taking into account levels of the stated configurations. Important plasma diagnostic information provided by the forbidden lines includes the ion temperature

Nursing structures in New Zealand public hospitals: current configurations.

PubMed

Hughes, Kerri-Ann; Carryer, Jennifer Barbara

2011-02-01

This article reports research reviewing the configuration of nursing leadership in New Zealand public hospitals. It represents an analysis of Phase 1 of a larger study. Leadership in nursing is critical if the profession is to meet the challenges of health services in the 21st century. The research focuses on how leadership in public hospitals is structured at a strategic level. The preliminary summary of findings of this phase of the research show that reporting lines between directors of nursing (DON) and the chief executive officer (CEO) are not always direct, and organizational charts and nursing structures are not readily aligned. Clear financial or budget holding reporting lines by nursing leadership are not easily identified, or are professional and operational accountability lines clearly defined. From 15 total responses received, the organizations are structured differently both organizationally and in the nursing structures.

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

Siauw, Timmy; Cunha, Adam; Berenson, Dmitry

Purpose: In this study, the authors introduce skew line needle configurations for high dose rate (HDR) brachytherapy and needle planning by integer program (NPIP), a computational method for generating these configurations. NPIP generates needle configurations that are specific to the anatomy of the patient, avoid critical structures near the penile bulb and other healthy structures, and avoid needle collisions inside the body. Methods: NPIP consisted of three major components: a method for generating a set of candidate needles, a needle selection component that chose a candidate needle subset to be inserted, and a dose planner for verifying that the finalmore » needle configuration could meet dose objectives. NPIP was used to compute needle configurations for prostate cancer data sets from patients previously treated at our clinic. NPIP took two user-parameters: a number of candidate needles, and needle coverage radius, {delta}. The candidate needle set consisted of 5000 needles, and a range of {delta} values was used to compute different needle configurations for each patient. Dose plans were computed for each needle configuration. The number of needles generated and dosimetry were analyzed and compared to the physician implant. Results: NPIP computed at least one needle configuration for every patient that met dose objectives, avoided healthy structures and needle collisions, and used as many or fewer needles than standard practice. These needle configurations corresponded to a narrow range of {delta} values, which could be used as default values if this system is used in practice. The average end-to-end runtime for this implementation of NPIP was 286 s, but there was a wide variation from case to case. Conclusions: The authors have shown that NPIP can automatically generate skew line needle configurations with the aforementioned properties, and that given the correct input parameters, NPIP can generate needle configurations which meet dose objectives and use as many or fewer needles than the current HDR brachytherapy workflow. Combined with robot assisted brachytherapy, this system has the potential to reduce side effects associated with treatment. A physical trial should be done to test the implant feasibility of NPIP needle configurations.« less

Lithology and characteristic of landslide in Gombel Hill by 2D geoelectric resistivity method using dipole-dipole configuration

NASA Astrophysics Data System (ADS)

Setyawan, Agus; Satria Fikri, Muhammad; Endro Suseno, Jatmiko; Fuad, Muhamad

2018-05-01

Gombel hill locates at Semarang, Central Java, Indonesia. Base on Semarang’s susceptiblity map zone, Gombel hill is belong to high susceptibility and instability zone. Instability may cause faults to Gombel hill area, unfortunately the geosciences research in Gombel is still lack. The geophysical survey has been conducted using 2D geoelectric resistivity method with dipole – dipole configuration to identify the lithology of landslide at Gombel hill. The data have been collected from three lines. The first and third line have 100 m length, and the second line have 80 m length with 5 m space in each lines. The data were processed and modelled using Res2Dinv software. From the first line, suspected there are two layers which formed the structure of the subsurface. The second line suspected there are three layers which formed the structure of the subsurface. And the last line suspected there are two layers which formed the structure of the subsurface. Overall, the landslide of Gombel hill area can be found with depth 5 m – 6 m and found at contact between clay and clay rock layer. We expect the results can be used for mitigation hazard and planning the developing infrastructure in Gombel area.

VizieR Online Data Catalog: Interferometric CO obs. of 126 CALIFA galaxies (Bolatto+, 2017)

NASA Astrophysics Data System (ADS)

Bolatto, A. D.; Wong, T.; Utomo, D.; Blitz, L.; Vogel, S. N.; Sanchez, S. F.; Barrera-Ballesteros, J.; Cao, Y.; Colombo, D.; Dannerbauer, H.; Garcia-Benito, R.; Herrera-Camus, R.; Husemann, B.; Kalinova, V.; Leroy, A. K.; Leung, G.; Levy, R. C.; Mast, D.; Ostriker, E.; Rosolowsky, E.; Sandstrom, K. M.; Teuben, P.; van de Ven, G.; Walter, F.

2018-05-01

Observations of the original 177 CALIFA galaxies sample were conducted by CARMA's E-array in late 2014, integrating 40 minutes per galaxy. 125 galaxies were subsequently (from 2014 December to 2015 March) observed in the more extended D configuration, with an additional ~3.5hr of integration per target. The CARMA correlator was configured with five 250MHz windows covering the 12CO line with 3.4km/s resolution and a 3000km/s velocity range, and three 500MHz windows covering the 13CO line with 14.3km/s resolution and a 3800km/s velocity range. (3 data files).

Flight-Test Evaluation of the Longitudinal Stability and Control Characteristics of 0.5-Scale Models of the Fairchild Lark Pilotless-Aircraft Configuration: Standard Configuration with Wing Flaps Deflected 60 Degrees and Model having Tail in Line with Wings, TED No. NACA 2387

NASA Technical Reports Server (NTRS)

Stone, David G.

1947-01-01

Flight tests were conducted at the Flight Test Station of the Pilotless Aircraft Research Division at Wallop Island, Va., to determine the longitudinal control and stability characteristics of 0.5-scale models of the Fairchild Lark pilotless aircraft with the tail in line with the wings a d with the horizontal wing flaps deflected 60 deg. The data were obtained by the use of a telemeter and by radar tracking.

Effect of metrology time delay on overlay APC

NASA Astrophysics Data System (ADS)

Carlson, Alan; DiBiase, Debra

2002-07-01

The run-to-run control strategy of lithography APC is primarily composed of a feedback loop as shown in the diagram below. It is known that the insertion of a time delay in a feedback loop can cause degradation in control performance and could even cause a stable system to become unstable, if the time delay becomes sufficiently large. Many proponents of integrated metrology methods have cited the damage caused by metrology time delays as the primary justification for moving from a stand-alone to integrated metrology. While there is little dispute over the qualitative form of this argument, there has been very light published about the quantitative effects under real fab conditions - precisely how much control is lost due to these time delays. Another issue regarding time delays is that the length of these delays is not typically fixed - they vary from lot to lot and in some cases this variance can be large - from one hour on the short side to over 32 hours on the long side. Concern has been expressed that the variability in metrology time delays can cause undesirable dynamics in feedback loops that make it difficult to optimize feedback filters and gains and at worst could drive a system unstable. By using data from numerous fabs, spanning many sizes and styles of operation, we have conducted a quantitative study of the time delay effect on overlay run- to-run control. Our analysis resulted in the following conclusions: (1) There is a significant and material relationship between metrology time delay and overlay control under a variety of real world production conditions. (2) The run-to-run controller can be configured to minimize sensitivity to time delay variations. (3) The value of moving to integrated metrology can be quantified.

Effects of channel tap spacing on delay-lock tracking

NASA Astrophysics Data System (ADS)

Dana, Roger A.; Milner, Brian R.; Bogusch, Robert L.

1995-12-01

High fidelity simulations of communication links operating through frequency selective fading channels require both accurate channel models and faithful reproduction of the received signal. In modern radio receivers, processing beyond the analog-to-digital converter (A/D) is done digitally, so a high fidelity simulation is actually an emulation of this digital signal processing. The 'simulation' occurs in constructing the output of the A/D. One approach to constructing the A/D output is to convolve the channel impulse response function with the combined impulse response of the transmitted modulation and the A/D. For both link simulations and hardware channel simulators, the channel impulse response function is then generated with a finite number of samples per chip, and the convolution is implemented in a tapped delay line. In this paper we discuss the effects of the channel model tap spacing on the performance of delay locked loops (DLLs) in both direct sequence and frequency hopped spread spectrum systems. A frequency selective fading channel is considered, and the channel impulse response function is constructed with an integer number of taps per modulation symbol or chip. The tracking loop time delay is computed theoretically for this tapped delay line channel model and is compared to the results of high fidelity simulations of actual DLLs. A surprising result is obtained. The performance of the DLL depends strongly on the number of taps per chip. As this number increases the DLL delay approaches the theoretical limit.

Optical resonators for true-time-delay beam steering

NASA Astrophysics Data System (ADS)

Gesell, Leslie H.; Evanko, Stephen M.

1996-06-01

Conventional true time delay beamforming and steering devices rely on switching between various lengths of delay line. Therefore only discrete delays are possible. Proposed is a new photonics concept for true time delay beamforming which provides a finely controlled continuum of delays with switching speeds on the order of 10's of nanoseconds or faster. The architecture uses an array of waveguide cavities with different resonate frequencies to channelize the signal. Each spectral component of the signal is phase shifted by an amount proportional to the frequency of that component and the desired time delay. These phase shifted spectral components are then summed to obtain the delayed signal. This paper provides an overview of the results of a Phase I SBIR contract where this concept has been refined and analyzed. The parameters for an operational system are determined and indication of the feasibility of this approach is given. Among the issues addressed are the requirements of the resonators and the methods necessary to implement fiber optic Bragg gratings as these resonators.

Fully unsteady subsonic and supersonic potential aerodynamics for complex aircraft configurations for flutter applications

NASA Technical Reports Server (NTRS)

Tseng, K.; Morino, L.

1975-01-01

A general theory for study, oscillatory or fully unsteady potential compressible aerodynamics around complex configurations is presented. Using the finite-element method to discretize the space problem, one obtains a set of differential-delay equations in time relating the potential to its normal derivative which is expressed in terms of the generalized coordinates of the structure. For oscillatory flow, the motion consists of sinusoidal oscillations around a steady, subsonic or supersonic flow. For fully unsteady flow, the motion is assumed to consist of constant subsonic or supersonic speed for time t or = 0 and of small perturbations around the steady state for time t 0.

Sound transmission through triple-panel structures lined with poroelastic materials

NASA Astrophysics Data System (ADS)

Liu, Yu

2015-03-01

In this paper, previous theories on the prediction of sound transmission loss for a double-panel structure lined with poroelastic materials are extended to address the problem of a triple-panel structure. Six typical configurations are considered for a triple-panel structure based on the method of coupling the porous layers to the facing panels which determines critically the sound insulation performance of the system. The transfer matrix method is employed to solve the system by applying appropriate types of boundary conditions for these configurations. The transmission loss of the triple-panel structures in a diffuse sound field is calculated as a function of frequency and compared with that of corresponding double-panel structures. Generally, the triple-panel structure with poroelastic linings has superior acoustic performance to the double-panel counterpart, remarkably in the mid-high frequency range and possibly at low frequencies, by selecting appropriate configurations in which those with two air gaps in the structure exhibit the best overall performance over the entire frequency range. The poroelastic lining significantly lowers the cut-on frequency above which the triple-panel structure exhibits noticeably higher transmission loss. Compared with a double-panel structure, the wider range of system parameters for a triple-panel structure due to the additional partition provides more design space for tuning the sound insulation performance. Despite the increased structural complexity, the triple-panel structure lined with poroelastic materials has the obvious advantages in sound transmission loss while without the penalties in weight and volume, and is hence a promising replacement for the widely used double-panel sandwich structure.

Evaluation of R1-6 gateway treatment alternatives for pedestrian crossings : final report.

DOT National Transportation Integrated Search

2016-02-01

A series of studies evaluated the Gateway configuration of R1-6 in-street signs. A Gateway configuration consists of an R1-6 sign on the centerline, an R1-6 signs on both edges of the roadway, and R1-6 signs on the lane lines if it is a multilane roa...

Evaluation of R1-6 gateway treatment alternatives for pedestrian crossings.

DOT National Transportation Integrated Search

2016-02-01

A series of studies evaluated the Gateway configuration of R1-6 in-street signs. A : Gateway configuration consists of an R1-6 sign on the centerline, an R1-6 signs on both edges of : the roadway, and R1-6 signs on the lane lines if it is a multilane...

Spatially Developing Secondary Instabilities and Attachment Line Instability in Supersonic Boundary Layers

NASA Technical Reports Server (NTRS)

Li, Fei; Choudhari, Meelan M.

2008-01-01

This paper reports on progress towards developing a spatial stability code for compressible shear flows with two inhomogeneous directions, such as crossflow dominated swept-wing boundary layers and attachment line flows. Certain unique aspects of formulating a spatial, two-dimensional eigenvalue problem for the secondary instability of finite amplitude crossflow vortices are discussed. A primary test case used for parameter study corresponds to the low-speed, NLF-0415(b) airfoil configuration as tested in the ASU Unsteady Wind Tunnel, wherein a spanwise periodic array of roughness elements was placed near the leading edge in order to excite stationary crossflow modes with a specified fundamental wavelength. The two classes of flow conditions selected for this analysis include those for which the roughness array spacing corresponds to either the naturally dominant crossflow wavelength, or a subcritical wavelength that serves to reduce the growth of the naturally excited dominant crossflow modes. Numerical predictions are compared with the measured database, both as indirect validation for the spatial instability analysis and to provide a basis for comparison with a higher Reynolds number, supersonic swept-wing configuration. Application of the eigenvalue analysis to the supersonic configuration reveals that a broad spectrum of stationary crossflow modes can sustain sufficiently strong secondary instabilities as to potentially cause transition over this configuration. Implications of this finding for transition control in swept wing boundary layers are examined. Finally, extension of the spatial stability analysis to supersonic attachment line flows is also considered.

Unified Approach To Control Of Motions Of Mobile Robots

NASA Technical Reports Server (NTRS)

Seraji, Homayoun

1995-01-01

Improved computationally efficient scheme developed for on-line coordinated control of both manipulation and mobility of robots that include manipulator arms mounted on mobile bases. Present scheme similar to one described in "Coordinated Control of Mobile Robotic Manipulators" (NPO-19109). Both schemes based on configuration-control formalism. Present one incorporates explicit distinction between holonomic and nonholonomic constraints. Several other prior articles in NASA Tech Briefs discussed aspects of configuration-control formalism. These include "Increasing the Dexterity of Redundant Robots" (NPO-17801), "Redundant Robot Can Avoid Obstacles" (NPO-17852), "Configuration-Control Scheme Copes with Singularities" (NPO-18556), "More Uses for Configuration Control of Robots" (NPO-18607/NPO-18608).

A Laboratory Demonstration of the Three-Dimensional Nature of In-Line Holography.

ERIC Educational Resources Information Center

Baez, Albert V.; Castro, George

1999-01-01

Describes an experiment in which two semi-transparent reticles and a photographic plate separated by several centimeters are illuminated by a monochromatic point source in a typical in-line configuration that results in a hologram that contains information from both reticles. (Author/WRM)

Effect of multilayer substrate configuration in horizontal subsurface flow constructed wetlands: assessment of treatment performance, biofilm development, and solids accumulation.

PubMed

Ding, Yanli; Lyu, Tao; Bai, Shaoyuan; Li, Zhenling; Ding, Haijing; You, Shaohong; Xie, Qinglin

2018-01-01

This study investigates the influence of multilayer substrate configuration in horizontal subsurface flow constructed wetlands (HSCWs) on their treatment performance, biofilm development, and solids accumulation. Three pilot-scale HSCWs were built to treat campus sewage and have been operational for 3 years. The HSCWs included monolayer (CW1), three-layer (CW3), and six-layer (CW6) substrate configurations with hydraulic conductivity of the substrate increasing from the surface to bottom in the multilayer CWs. It was demonstrated the pollutant removal performance after a 3-year operation improved in the multilayer HSCWs (49-80%) compared to the monolayer HSCW (29-41%). Simultaneously, the multilayer HSCWs exhibited significant features that prevented clogging compared to the monolayer configuration. The amount of accumulated solids was notably higher in the monolayer CW compared to multilayer CWs. Further, multilayer HSCWs could delay clogging by providing higher biofilm development for organics removal and consequently, lesser solids accumulations. Principal component analysis strongly supported the visualization of the performance patterns in the present study and showed that multilayer substrate configuration, season, and sampling locations significantly influenced biofilm growth and solids accumulation. Finally, the present study provided important information to support the improved multilayer configured HSCW implication in the future.

SALT long-slit spectroscopy of CTS C30.10: two-component Mg II line

NASA Astrophysics Data System (ADS)

Modzelewska, J.; Czerny, B.; Hryniewicz, K.; Bilicki, M.; Krupa, M.; Świȩtoń, A.; Pych, W.; Udalski, A.; Adhikari, T. P.; Petrogalli, F.

2014-10-01

Context. Quasars can be used as a complementary tool to SN Ia to probe the distribution of dark energy in the Universe by measuring the time delay of the emission line with respect to the continuum. The understanding of the Mg II emission line structure is important for cosmological application and for the black hole mass measurements of intermediate redshift quasars. Aims: Knowing the shape of Mg II line and its variability allows for identifying which part of the line should be used to measure the time delay and the black hole mass. We thus aim at determining the structure and the variability of the Mg II line, as well as the underlying Fe II pseudo-continuum. Methods: We performed five spectroscopic observations of a quasar CTS C30.10 (z = 0.9000) with the SALT telescope between December 2012 and March 2014, and we studied the variations in the spectral shape in the 2700 Å-2900 Å rest frame. Results: We show that the Mg II line in this source consists of two kinematic components, which makes the source representative of type B quasars. Both components were modeled well with a Lorentzian shape, and they vary in a similar way. The Fe II contribution seems to be related only to the first (blue) Mg II component. Broad band spectral fitting instead favor the use of the whole line profile. The contribution of the narrow line region to Mg II is very low, below 2%. The Mg II variability is lower than the variability of the continuum, which is consistent with the simple reprocessing scenario. The variability level of CTS C30.10 and the measurement accuracy of the line and continuum is high enough to expect that further monitoring will allow the time delay between the Mg II line and continuum to be measured. Based on observations made with the Southern African Large Telescope (SALT) under program 2012-2-POL-003 and 2013-1-POL-RSA-002 (PI: B. Czerny).Spectra shown in Figs. 3 and 4 are only available in electronic form at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/570/A53Table 1 is available in electronic form at http://www.aanda.org

Magnetically excited flexural plate wave apparatus

DOEpatents

Martin, Stephen J.; Butler, Michael A.; Frye, Gregory C.; Smith, James H.

1998-01-01

A non-piezoelectric flexural plate wave apparatus having meander-line transducers mounted on a non-piezoelectric membrane. A static magnetic field is directed perpendicularly to the conductive legs of the transducers in the plane of the membrane. Single-port, two-port, resonant, non-resonant, eigenmode, and delay-line modes may be employed.

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

Fradkin, D.B.; Hull, L.M.; Laabs, G.W.

The results of dynamic sled track performance testing of advanced tandem configuration shaped-charge warheads against multiple-reactive-element tank armors are presented. Tandem configurations utilizing both currently fielded and experimental shaped-charge warheads were tested. Sled velocities used were between 400 and 1100 ft/s (Mach number 0.35 to 0.95), typical of the terminal approach velocity of TOW-type antitank missiles. High-speed motion pictures (5000 frames/s) of the sled in operation and a typical mock missile'' warhead package approaching the target are shown. Details of the sled design and fabrication and of the warhead package design and fabrication are presented. Sled track instrumentation is discussed.more » This instrumentation includes foil make/break switches and associated time interval meters (TIM) and digital delay units (DDU), magnetic Hall-effect transistors for measuring sled trajectory, and flash x-rays (FXR). Methods for timing the x-rays are presented. Schematic functional diagrams of the experimental setups are also given. Evidence of the ability to accurately time the delay between precursor and main warheads for even very long time delays are presented. FXR pictures illustrate the dynamics of the interaction of the jets with various target elements. The interaction dynamics of the jets is discussed in relation to the overall penetration performance of the tandem warhead. The use of x-ray fluorescence spectroscopy to help diagnose interaction dynamics is illustrated. The results of a test utilizing the missile propulsion rocket motor as a blast shield is presented in this paper. 2 refs., 22 figs.« less

1.0 T open-configuration magnetic resonance-guided microwave ablation of pig livers in real time

PubMed Central

Dong, Jun; Zhang, Liang; Li, Wang; Mao, Siyue; Wang, Yiqi; Wang, Deling; Shen, Lujun; Dong, Annan; Wu, Peihong

2015-01-01

The current fastest frame rate of each single image slice in MR-guided ablation is 1.3 seconds, which means delayed imaging for human at an average reaction time: 0.33 seconds. The delayed imaging greatly limits the accuracy of puncture and ablation, and results in puncture injury or incomplete ablation. To overcome delayed imaging and obtain real-time imaging, the study was performed using a 1.0-T whole-body open configuration MR scanner in the livers of 10 Wuzhishan pigs. A respiratory-triggered liver matrix array was explored to guide and monitor microwave ablation in real-time. We successfully performed the entire ablation procedure under MR real-time guidance at 0.202 s, the fastest frame rate for each single image slice. The puncture time ranged from 23 min to 3 min. For the pigs, the mean puncture time was shorted to 4.75 minutes and the mean ablation time was 11.25 minutes at power 70 W. The mean length and widths were 4.62 ± 0.24 cm and 2.64 ± 0.13 cm, respectively. No complications or ablation related deaths during or after ablation were observed. In the current study, MR is able to guide microwave ablation like ultrasound in real-time guidance showing great potential for the treatment of liver tumors. PMID:26315365

Pattern reverberation in networks of excitable systems with connection delays

NASA Astrophysics Data System (ADS)

Lücken, Leonhard; Rosin, David P.; Worlitzer, Vasco M.; Yanchuk, Serhiy

2017-01-01

We consider the recurrent pulse-coupled networks of excitable elements with delayed connections, which are inspired by the biological neural networks. If the delays are tuned appropriately, the network can either stay in the steady resting state, or alternatively, exhibit a desired spiking pattern. It is shown that such a network can be used as a pattern-recognition system. More specifically, the application of the correct pattern as an external input to the network leads to a self-sustained reverberation of the encoded pattern. In terms of the coupling structure, the tolerance and the refractory time of the individual systems, we determine the conditions for the uniqueness of the sustained activity, i.e., for the functionality of the network as an unambiguous pattern detector. We point out the relation of the considered systems with cyclic polychronous groups and show how the assumed delay configurations may arise in a self-organized manner when a spike-time dependent plasticity of the connection delays is assumed. As excitable elements, we employ the simplistic coincidence detector models as well as the Hodgkin-Huxley neuron models. Moreover, the system is implemented experimentally on a Field-Programmable Gate Array.

Effects of deflected thrust on the longitudinal aerodynamic characteristics of a close-coupled wing-canard configuration. [in the Langley V/STOL tunnel

NASA Technical Reports Server (NTRS)

Yip, L. P.; Paulson, J. W., Jr.

1977-01-01

The effects of power on the longitudinal aerodynamic characteristics of a close-coupled wing-canard fighter configuration with partial-span rectangular nozzles at the trailing edge of the wing were investigated. Data were obtained on a basic wing-strake configuration for nozzle and flap deflections from 0 deg to 30 deg and for nominal thrust coefficients from 0 to 0.30. The model was tested over an angle-of-attack range from -2 deg to 40 deg at Mach numbers of 0.15 and 0.18. Results show substantial improvements in lift-curve slope, in maximum lift, and in drag-due-to-lift efficiency when the canard and strakes have been added to the basic wing-fuselage (wing-alone) configuration. Addition of power increased both lift-curve slope and maximum lift, improved longitudinal stability, and reduced drag due to lift on both the wing-canard and wing-canard-strake configurations. These beneficial effects are primarily derived from boundary-layer control due to moderate thrust coefficients which delay flow separation on the nozzle and inboard portion of the wing flaps.

Microwave radiometry as a tool to calibrate tropospheric water-vapor delay

NASA Technical Reports Server (NTRS)

Resch, G. M.; Claflin, E. S.

1980-01-01

Microwave radiometers were used to measure the emission line due to the water vapor molecules of atmospheric emission. Four separate field tests were completed which compared radiometers to other techniques which measure water vapor. It is shown that water vapor induced delay can be estimated with an accuracy of plus or minus 2 cm for elevation angles above 17 degrees.

A High-Linearity, Ring-Oscillator-Based, Vernier Time-to-Digital Converter Utilizing Carry Chains in FPGAs

NASA Astrophysics Data System (ADS)

Cui, Ke; Ren, Zhongjie; Li, Xiangyu; Liu, Zongkai; Zhu, Rihong

2017-01-01

Time-to-digital converters (TDCs) using dedicated carry chains of field programmable gate arrays (FPGAs) are usually organized in tapped-delay-line type which are intensively researched in recent years. However this method incurs poor differential nonlinearity (DNL) which arises from the inherent uneven bin granularity. This paper proposes a TDC architecture which utilizes the carry chains in a quite different manner in order to alleviate this long-standing problem. Two independent carry chains working as the delay lines for the fine time interpolation are organized in a ring-oscillator-based Vernier style and the time difference between them is finely adjusted by assigning different number of basic delay cells. A specific design flow is described to obtain the desired delay difference. The TDC was implemented on a Stratix III FPGA. Test results show that the obtained resolution is 31 ps and the DNL\\INL is in the range of (-0.080 LSB, 0.073 LSB)(-0.087 LSB, 0.091 LSB). This demonstrates that the proposed architecture greatly improves linearity compared to previous techniques. Additionally the resource cost is rather low which uses only 319 LUTs and 104 registers per TDC channel.

Do Dogs Know the Trammel of Archimedes?

ERIC Educational Resources Information Center

Schwartz, Mark

2011-01-01

The refraction problem, well-known in calculus and physics, continues to reveal new insights. This paper presents a geometric solution in which the trammel of Archimedes plays the prominent role. When properly configured, the trammel generates an ellipse and its family of normal lines. One normal line in particular intersects the boundary…

Improved cryogenic refrigeration system

NASA Technical Reports Server (NTRS)

Higa, W. H.

1967-01-01

Two-position shuttle valve simplifies valving arrangement and crank-shaft configuration in gas-balancing and Stirling-cycle refrigeration systems used to produce temperatures below 173 degrees K. It connects the displacer and regenerator alternately to the supply line or the return line of the compressor, and establishes constant pressure on the drive piston.

Acoustic attenuation design requirements established through EPNL parametric trades

NASA Technical Reports Server (NTRS)

Veldman, H. F.

1972-01-01

An optimization procedure for the provision of an acoustic lining configuration that is balanced with respect to engine performance losses and lining attenuation characteristics was established using a method which determined acoustic attenuation design requirements through parametric trade studies using the subjective noise unit of effective perceived noise level (EPNL).

Interaction of Airspace Partitions and Traffic Flow Management Delay

NASA Technical Reports Server (NTRS)

Palopo, Kee; Chatterji, Gano B.; Lee, Hak-Tae

2010-01-01

To ensure that air traffic demand does not exceed airport and airspace capacities, traffic management restrictions, such as delaying aircraft on the ground, assigning them different routes and metering them in the airspace, are implemented. To reduce the delays resulting from these restrictions, revising the partitioning of airspace has been proposed to distribute capacity to yield a more efficient airspace configuration. The capacity of an airspace partition, commonly referred to as a sector, is limited by the number of flights that an air traffic controller can safely manage within the sector. Where viable, re-partitioning of the airspace distributes the flights over more efficient sectors and reduces individual sector demand. This increases the overall airspace efficiency, but requires additional resources in some sectors in terms of controllers and equipment, which is undesirable. This study examines the tradeoff of the number of sectors designed for a specified amount of traffic in a clear-weather day and the delays needed for accommodating the traffic demand. Results show that most of the delays are caused by airport arrival and departure capacity constraints. Some delays caused by airspace capacity constraints can be eliminated by re-partitioning the airspace. Analyses show that about 360 high-altitude sectors, which are approximately today s operational number of sectors of 373, are adequate for delays to be driven solely by airport capacity constraints for the current daily air traffic demand. For a marginal increase of 15 seconds of average delay, the number of sectors can be reduced to 283. In addition, simulations of traffic growths of 15% and 20% with forecasted airport capacities in the years 2018 and 2025 show that delays will continue to be governed by airport capacities. In clear-weather days, for small increases in traffic demand, increasing sector capacities will have almost no effect on delays.

Transmission Scheduling and Routing Algorithms for Delay Tolerant Networks

NASA Technical Reports Server (NTRS)

Dudukovich, Rachel; Raible, Daniel E.

2016-01-01

The challenges of data processing, transmission scheduling and routing within a space network present a multi-criteria optimization problem. Long delays, intermittent connectivity, asymmetric data rates and potentially high error rates make traditional networking approaches unsuitable. The delay tolerant networking architecture and protocols attempt to mitigate many of these issues, yet transmission scheduling is largely manually configured and routes are determined by a static contact routing graph. A high level of variability exists among the requirements and environmental characteristics of different missions, some of which may allow for the use of more opportunistic routing methods. In all cases, resource allocation and constraints must be balanced with the optimization of data throughput and quality of service. Much work has been done researching routing techniques for terrestrial-based challenged networks in an attempt to optimize contact opportunities and resource usage. This paper examines several popular methods to determine their potential applicability to space networks.

Displacement sensors using soft magnetostrictive alloys

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

Hristoforou, E.; Reilly, R.E.

1994-09-01

The authors report results on the response of a family of displacement sensors, which are based on the magnetostrictive delay line (MDL) technique, using current conductor orthogonal to the MDL. Such sensing technique is based on the change of the magnetic circuit and the acoustic stress point of origin due to the displacement of a soft magnetic material above it. Integrated arrays of sensors can be obtained due to the acoustic delay line technique and they can be used as tactile arrays, digitizers or devices for medical application (gait analysis etc.), while absence of hysteresis and low cost of manufacturingmore » make them competent in this sector of sensor market.« less

Wavelength-stepped, actively mode-locked fiber laser based on wavelength-division-multiplexed optical delay lines

NASA Astrophysics Data System (ADS)

Lee, Eunjoo; Kim, Byoung Yoon

2017-12-01

We propose a new scheme for an actively mode-locked wavelength-swept fiber laser that produces a train of discretely wavelength-stepped pulses from a short fiber cavity. Pulses with different wavelengths are split and combined by standard wavelength division multiplexers with fiber delay lines. As a proof of concept, we demonstrate a laser using an erbium doped fiber amplifier and commercially available wavelength-division multiplexers with wavelength spacing of 0.8 nm. The results show simultaneous mode-locking at three different wavelengths. Laser output parameters in time domain, optical and radio frequency spectral domain, and the noise characteristics are presented. Suggestions for the improved design are discussed.

Neural node network and model, and method of teaching same

DOEpatents

Parlos, A.G.; Atiya, A.F.; Fernandez, B.; Tsai, W.K.; Chong, K.T.

1995-12-26

The present invention is a fully connected feed forward network that includes at least one hidden layer. The hidden layer includes nodes in which the output of the node is fed back to that node as an input with a unit delay produced by a delay device occurring in the feedback path (local feedback). Each node within each layer also receives a delayed output (crosstalk) produced by a delay unit from all the other nodes within the same layer. The node performs a transfer function operation based on the inputs from the previous layer and the delayed outputs. The network can be implemented as analog or digital or within a general purpose processor. Two teaching methods can be used: (1) back propagation of weight calculation that includes the local feedback and the crosstalk or (2) more preferably a feed forward gradient decent which immediately follows the output computations and which also includes the local feedback and the crosstalk. Subsequent to the gradient propagation, the weights can be normalized, thereby preventing convergence to a local optimum. Education of the network can be incremental both on and off-line. An educated network is suitable for modeling and controlling dynamic nonlinear systems and time series systems and predicting the outputs as well as hidden states and parameters. The educated network can also be further educated during on-line processing. 21 figs.

Delayed expression of SAGs correlates with longevity in CMS wheat plants compared to its fertile plants.

PubMed

Semwal, Vimal Kumar; Singh, Bhupinder; Khanna-Chopra, Renu

2014-04-01

Reproductive sinks regulate monocarpic senescence in crop plants. Monocarpic senescence was studied in wheat fertile (cv. HW 2041) and its isonuclear cytoplasmic male sterile (CMS) line. CMS plants exhibited slower rate of senescence accompanied by longer green leaf area duration and slower deceleration in chlorophyll, protein content, PN and rubisco content coupled with lower protease activities than fertile (F) plants. CMS plants also exhibited lower ROS levels and less membrane damage than F plants. CMS plants maintained better antioxidant defense, less oxidative damage in chloroplast and higher transcript levels of both rbcL and rbcS genes during senescence than F plants. F plants exhibited early induction and higher expression of SAGs like serine and cysteine proteases, glutamine synthetases GS1 and GS2, WRKY53 transcription factor and decline in transcript levels of CAT1 and CAT2 genes than CMS plants. Hence, using genetically fertile and its CMS line of wheat it is confirmed that delayed senescence in the absence of reproductive sinks is linked with slower protein oxidation, rubisco degradation and delayed activation of SAGs. Better antioxidant defense in chloroplasts at later stages of senescence was able to mitigate the deleterious effects of ROS in CMS plants. We propose that delayed increase in ROS in cytoplasmic male sterile wheat plants resulted in delayed activation of WRKY53, SAGs and the associated biochemical changes than fertile plants.

Neural node network and model, and method of teaching same

DOEpatents

Parlos, Alexander G.; Atiya, Amir F.; Fernandez, Benito; Tsai, Wei K.; Chong, Kil T.

1995-01-01

The present invention is a fully connected feed forward network that includes at least one hidden layer 16. The hidden layer 16 includes nodes 20 in which the output of the node is fed back to that node as an input with a unit delay produced by a delay device 24 occurring in the feedback path 22 (local feedback). Each node within each layer also receives a delayed output (crosstalk) produced by a delay unit 36 from all the other nodes within the same layer 16. The node performs a transfer function operation based on the inputs from the previous layer and the delayed outputs. The network can be implemented as analog or digital or within a general purpose processor. Two teaching methods can be used: (1) back propagation of weight calculation that includes the local feedback and the crosstalk or (2) more preferably a feed forward gradient decent which immediately follows the output computations and which also includes the local feedback and the crosstalk. Subsequent to the gradient propagation, the weights can be normalized, thereby preventing convergence to a local optimum. Education of the network can be incremental both on and off-line. An educated network is suitable for modeling and controlling dynamic nonlinear systems and time series systems and predicting the outputs as well as hidden states and parameters. The educated network can also be further educated during on-line processing.

Cytotoxic effects of ultra-diluted remedies on breast cancer cells.

PubMed

Frenkel, Moshe; Mishra, Bal Mukund; Sen, Subrata; Yang, Peiying; Pawlus, Alison; Vence, Luis; Leblanc, Aimee; Cohen, Lorenzo; Banerji, Pratip; Banerji, Prasanta

2010-02-01

The use of ultra-diluted natural products in the management of disease and treatment of cancer has generated a lot of interest and controversy. We conducted an in vitro study to determine if products prescribed by a clinic in India have any effect on breast cancer cell lines. We studied four ultra-diluted remedies (Carcinosin, Phytolacca, Conium and Thuja) against two human breast adenocarcinoma cell lines (MCF-7 and MDA-MB-231) and a cell line derived from immortalized normal human mammary epithelial cells (HMLE). The remedies exerted preferential cytotoxic effects against the two breast cancer cell lines, causing cell cycle delay/arrest and apoptosis. These effects were accompanied by altered expression of the cell cycle regulatory proteins, including downregulation of phosphorylated Rb and upregulation of the CDK inhibitor p27, which were likely responsible for the cell cycle delay/arrest as well as induction of the apoptotic cascade that manifested in the activation of caspase 7 and cleavage of PARP in the treated cells. The findings demonstrate biological activity of these natural products when presented at ultra-diluted doses. Further in-depth studies with additional cell lines and animal models are warranted to explore the clinical applicability of these agents.

Switched-beam radiometer front-end network analysis

NASA Technical Reports Server (NTRS)

Trew, R. J.; Bilbro, G. L.

1994-01-01

The noise figure performance of various delay-line networks fabricated from microstrip lines with varying number of elements was investigated using a computer simulation. The effects of resistive losses in both the transmission lines and power combiners were considered. In general, it is found that an optimum number of elements exists, depending upon the resistive losses present in the network. Small resistive losses are found to have a significant degrading effect upon the noise figure performance of the array. Extreme stability in switching characteristics is necessary to minimize the nondeterministic noise of the array. For example, it is found that a 6 percent tolerance on the delay-line lengths will produce a 0.2 db uncertainty in the noise figure which translates into a 13.67 K temperature uncertainty generated by the network. If the tolerance can be held to 2 percent, the uncertainty in noise figure and noise temperature will be 0.025 db and 1.67 K, respectively. Three phase shift networks fabricated using a commercially available PIN diode switch were investigated. Loaded-line phase shifters are found to have desirable RF and noise characteristics and are attractive components for use in phased-array networks.

Coupled resonator optical waveguide sensors: sensitivity and the role of slow light

NASA Astrophysics Data System (ADS)

Terrel, Matthew A.; Digonnet, Michel J. F.; Fan, Shanhui

2009-05-01

We compare the sensitivity of two configurations of coupled resonator optical waveguide (CROW) gyroscopes proposed by others to conventional optical gyroscopes. In both cases, we demonstrate that for equal device footprint and loss, neither of these CROW gyroscopes configurations is more sensitive than its conventional counterpart. In all cases, loss ultimately limits the maximum rotation sensitivity. The fact that light travels more slowly (i.e., with a greater group delay) in a CROW than in a fiber therefore has no effect on sensitivity. The only benefit slow light does have is that it reduces the device length requirement, or equivalently it increases the sensitivity per unit length. However, we show that this improvement is quantitatively the same as in an RFOG. These conclusions are not limited to these two CROW configurations or to rotation sensing, but applicable to any measurand that modifies the phase of the signal(s) traveling in the resonators.

Modeling the Influence of Stitching on Delamination Growth in Stitched Warp-Knit Composite Lap Joints

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1999-01-01

The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and analytical study. The experimental study was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation of the debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The strain energy release rates at the debond front were calculated using a finite element-based technique. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches effectively reduced mode I to zero, but had less of an effect on modes II and III.

Preliminary aerodynamic design considerations for advanced laminar flow aircraft configurations

NASA Technical Reports Server (NTRS)

Johnson, Joseph L., Jr.; Yip, Long P.; Jordan, Frank L., Jr.

1986-01-01

Modern composite manufacturing methods have provided the opportunity for smooth surfaces that can sustain large regions of natural laminar flow (NLF) boundary layer behavior and have stimulated interest in developing advanced NLF airfoils and improved aircraft designs. Some of the preliminary results obtained in exploratory research investigations on advanced aircraft configurations at the NASA Langley Research Center are discussed. Results of the initial studies have shown that the aerodynamic effects of configuration variables such as canard/wing arrangements, airfoils, and pusher-type and tractor-type propeller installations can be particularly significant at high angles of attack. Flow field interactions between aircraft components were shown to produce undesirable aerodynamic effects on a wing behind a heavily loaded canard, and the use of properly designed wing leading-edge modifications, such as a leading-edge droop, offset the undesirable aerodynamic effects by delaying wing stall and providing increased stall/spin resistance with minimum degradation of laminar flow behavior.

Mark 3 VLBI system: Tropospheric calibration subsystems

NASA Technical Reports Server (NTRS)

Resch, G. M.

1980-01-01

Tropospheric delay calibrations are implemented in the Mark 3 system with two subsystems. Estimates of the dry component of tropospheric delay are provided by accurate barometric data from a subsystem of surface meteorological sensors (SMS). An estimate of the wet component of tropospheric delay is provided by a water vapor radiometer (WVR). Both subsystems interface directly to the ASCII Transceiver bus of the Mark 3 system and are operated by the control computer. Seven WVR's under construction are designed to operate in proximity to a radio telescope and can be commanded to point along the line-of-sight to a radio source. They should provide a delay estimate that is accurate to the + or - 2 cm level.

Stability and chaotification of vibration isolation floating raft systems with time-delayed feedback control.

PubMed

Li, Y L; Xu, D L; Fu, Y M; Zhou, J X

2011-09-01

This paper presents a systematic study on the stability of a two-dimensional vibration isolation floating raft system with a time-delayed feedback control. Based on the generalized Sturm criterion, the critical control gain for the delay-independent stability region and critical time delays for the stability switches are derived. The critical conditions can provide a theoretical guidance of chaotification design for line spectra reduction. Numerical simulations verify the correctness of the approach. Bifurcation analyses reveal that chaotification is more likely to occur in unstable region defined by these critical conditions, and the stiffness of the floating raft and mass ratio are the sensitive parameters to reduce critical control gain.

The 4d8-(4d74f + 4d76p + 4p54d9) transitions in the spectrum of five times ionized indium (In VI)

NASA Astrophysics Data System (ADS)

Ryabtsev, A. N.; Tauheed, A.; Swapnil; Kildiyarova, R. R.; Kononov, E. Ya

2018-06-01

The spectrum of five times ionized indium excited in a vacuum spark has been studied in the wavelength region 180-250 Å using a 3 m grazing incidence spectrograph. Transitions from highly excited interacting configurations 4d74f + 4d76p + 4p54d9 to the ground state 4d8 configuration were studied. 165 spectral lines were identified and 81 levels of the excited configurations were found.

Brief Report: Effect of Spatial Complexity on Visual Short-Term Memory and Self-Reported Autistic-Like Traits in Typically Developed Individuals

ERIC Educational Resources Information Center

Takahashi, Junichi; Gyoba, Jiro; Yamawaki, Nozomi

2013-01-01

This report examines effects of the spatial complexity of configurations on visual short-term memory (VSTM) capacity for individuals from the general population differing on autism-spectrum quotient (AQ) scores. During each trial, nine-line segments with various orientations were arrayed in simple or complex configurations and presented in both…

Core Flight System (cFS) a Low Cost Solution for SmallSats

NASA Technical Reports Server (NTRS)

McComas, David; Strege, Susanne; Wilmot, Jonathan

2015-01-01

The cFS is a FSW product line that uses a layered architecture and compile-time configuration parameters which make it portable and scalable for a wide range of platforms. The software layers that defined the application run-time environment are now under a NASA-wide configuration control board with the goal of sustaining an open-source application ecosystem.

Frustration and curvature - Glasses and the cholesteric blue phase

NASA Technical Reports Server (NTRS)

Sethna, J. P.

1983-01-01

An analogy is drawn between continuum elastic theories of the blue phase of cholesteric liquid crystals and recent theories of frustration in configurational glasses. Both involve the introduction of a lattice of disclination lines to relieve frustration; the frustration is due to an intrinsic curvature in the natural form of parallel transport. A continuum theory of configurational glasses is proposed.

Generalized EC&LSS computer program configuration control

NASA Technical Reports Server (NTRS)

Blakely, R. L.

1976-01-01

The generalized environmental control and life support system (ECLSS) computer program (G189A) simulation of the shuttle orbiter ECLSS was upgraded. The G189A component model configuration was changed to represent the current PV102 and subsequent vehicle ECLSS configurations as defined by baseline ARS and ATCS schematics. The diagrammatic output schematics of the gas, water, and freon loops were also revised to agree with the new ECLSS configuration. The accuracy of the transient analysis was enhanced by incorporating the thermal mass effects of the equipment, structure, and fluid in the ARS gas and water loops and in the ATCS freon loops. The sources of the data used to upgrade the simulation are: (1) ATCS freon loop line sizes and lengths; (2) ARS water loop line sizes and lengths; (3) ARS water loop and ATCS freon loop component and equipment weights; and (4) ARS cabin and avionics bay thermal capacitance and conductance values. A single G189A combination master program library tape was generated which contains all of the master program library versions which were previously maintained on separate tapes. A new component subroutine, PIPETL, was developed and incorporated into the G189A master program library.

Reverberation Mapping of the Broad Line Region: Application to a Hydrodynamical Line-driven Disk Wind Solution

NASA Astrophysics Data System (ADS)

Waters, Tim; Kashi, Amit; Proga, Daniel; Eracleous, Michael; Barth, Aaron J.; Greene, Jenny

2016-08-01

The latest analysis efforts in reverberation mapping are beginning to allow reconstruction of echo images (or velocity-delay maps) that encode information about the structure and kinematics of the broad line region (BLR) in active galactic nuclei (AGNs). Such maps can constrain sophisticated physical models for the BLR. The physical picture of the BLR is often theorized to be a photoionized wind launched from the AGN accretion disk. Previously we showed that the line-driven disk wind solution found in an earlier simulation by Proga and Kallman is virialized over a large distance from the disk. This finding implies that, according to this model, black hole masses can be reliably estimated through reverberation mapping techniques. However, predictions of echo images expected from line-driven disk winds are not available. Here, after presenting the necessary radiative transfer methodology, we carry out the first calculations of such predictions. We find that the echo images are quite similar to other virialized BLR models such as randomly orbiting clouds and thin Keplerian disks. We conduct a parameter survey exploring how echo images, line profiles, and transfer functions depend on both the inclination angle and the line opacity. We find that the line profiles are almost always single peaked, while transfer functions tend to have tails extending to large time delays. The outflow, despite being primarily equatorially directed, causes an appreciable blueshifted excess on both the echo image and line profile when seen from lower inclinations (I≲ 45^\\circ ). This effect may be observable in low ionization lines such as {{H}}β .

Delay-Line Three-Dimensional Position Sensitive Radiation Detection

NASA Astrophysics Data System (ADS)

Jeong, Manhee

High-resistivity silicon(Si) in large volumes and with good charge carrier transport properties has been produced and achieved success as a radiation detector material over the past few years due to its relatively low cost as well as the availability of well-established processing technologies. One application of that technology is in the fabrication of various position-sensing topologies from which the incident radiation's direction can be determined. We have succeeded in developing the modeling tools for investigating different position-sensing schemes and used those tools to examine both amplitude-based and time-based methods, an assessment that indicates that fine position-sensing can be achieved with simpler readout designs than are conventionally deployed. This realization can make ubiquitous and inexpensive deployment of special nuclear materials (SNM) detecting technology becomes more feasible because if one can deploy position-sensitive semiconductor detectors with only one or two contacts per side. For this purpose, we have described the delay-line radiation detector and its optimized fabrication. The semiconductor physics were simulated, the results from which guided the fabrication of the guard ring structure and the detector electrode, both of which included metal-field-plates. The measured improvement in the leakage current was confirmed with the fabricated devices, and the structures successfully suppressed soft-breakdown. We also demonstrated that fabricating an asymmetric strip-line structure successfully minimizing the pulse shaping and increases the distance through which one can propagate the information of the deposited charge distribution. With fabricated delay-line detectors we can acquire alpha spectra (Am-241) and gamma spectra (Ba-133, Co-57 and Cd-109). The delay-line detectors can therefore be used to extract the charge information from both ion and gamma-ray interactions. Furthermore, standard charge-sensitive circuits yield high SNR pulses. The detectors and existing electronics can therefore be used to yield imaging instruments for neutron and gamma-rays, in the case of silicon. For CZT, we would prefer to utilize current sensing to be able to clearly isolate the effects of the various charge-transport non-idealities, the full realization of which awaits the fabrication of the custom-designed TIA chip.

Transonic Aerodynamic Loading Characteristics of a Wing-Body-Tail Combination Having a 52.5 deg. Sweptback Wing of Aspect Ratio 3 With Conical Wing Camber and Body Indentation for a Design Mach Number of Square Root of 2

NASA Technical Reports Server (NTRS)

Cassetti, Marlowe D.; Re, Richard J.; Igoe, William B.

1961-01-01

An investigation has been made of the effects of conical wing camber and body indentation according to the supersonic area rule on the aerodynamic wing loading characteristics of a wing-body-tail configuration at transonic speeds. The wing aspect ratio was 3, taper ratio was 0.1, and quarter-chord-line sweepback was 52.5 deg. with 3-percent-thick airfoil sections. The tests were conducted in the Langley 16-foot transonic tunnel at Mach numbers from 0.80 to 1.05 and at angles of attack from 0 deg. to 14 deg., with Reynolds numbers based on mean aerodynamic chord varying from 7 x 10(exp 6) to 8 x 10(exp 6). Conical camber delayed wing-tip stall and reduced the severity of the accompanying longitudinal instability but did not appreciably affect the spanwise load distribution at angles of attack below tip stall. Body indentation reduced the transonic chordwise center-of-pressure travel from about 8 percent to 5 percent of the mean aerodynamic chord.

Fuel cell technology program

NASA Technical Reports Server (NTRS)

1971-01-01

The results of a solid polymer electrolyte fuel cell development program are summarized. A base line design was defined, and materials and components of the base line configuration were fabricated and tested. Concepts representing base line capability extensions in the areas of life, power, specific weight and volume, versatility of operation, field maintenance, and thermal control were identified and evaluated. Liaison and coordination with space shuttle contractors resulted in the exchange of engineering data.

Magnetic field configuration associated with solar gamma ray flares in June, 1991

NASA Technical Reports Server (NTRS)

Hagyard, M. J.; West, E. A.; Smith, J. E.; Trussart, F.-M.; Kenney, E. G.

1992-01-01

The vector magnetic field configuration of the solar active region AR 6659 that produced very high levels of flare activity in Jun. 1991 is described. The morphology and evolution of the photospheric fields are described for the period 7-10 Jun., and the flares taking place around these dates and their locations relative to the photospheric fields are indicated. By comparing the observed vector field with the potential field calculated from the observed line-of-sight flux, we identify the nonpotential characteristics of the fields along the magnetic neutral lines where the flares were observed. These results are compared with those from the earlier study of gamma-ray flares.

Contingent attentional capture or delayed allocation of attention?

NASA Technical Reports Server (NTRS)

Remington, R. W.; Folk, C. L.; McLean, J. P.

2001-01-01

Under certain circumstances, external stimuli will elicit an involuntary shift of spatial attention, referred to as attentional capture. According to the contingent involuntary orienting account (Folk, Remington, & Johnston, 1992), capture is conditioned by top-down factors that set attention to respond involuntarily to stimulus properties relevant to one's behavioral goals. Evidence for this comes from spatial cuing studies showing that a spatial cuing effect is observed only when cues have goal-relevant properties. Here, we examine alternative, decision-level explanations of the spatial cuing effect that attribute evidence of capture to postpresentation delays in the voluntary allocation of attention, rather than to on-line involuntary shifts in direct response to the cue. In three spatial cuing experiments, delayed-allocation accounts were tested by examining whether items at the cued location were preferentially processed. The experiments provide evidence that costs and benefits in spatial cuing experiments do reflect the on-line capture of attention. The implications of these results for models of attentional control are discussed.

Experimental Realization of a Reflections-Free Compact Delay Line Based on a Photonic Topological Insulator

PubMed Central

Lai, Kueifu; Ma, Tsuhsuang; Bo, Xiao; Anlage, Steven; Shvets, Gennady

2016-01-01

Electromagnetic (EM) waves propagating through an inhomogeneous medium are generally scattered whenever the medium’s electromagnetic properties change on the scale of a single wavelength. This fundamental phenomenon constrains how optical structures are designed and interfaced with each other. Recent theoretical work indicates that electromagnetic structures collectively known as photonic topological insulators (PTIs) can be employed to overcome this fundamental limitation, thereby paving the way for ultra-compact photonic structures that no longer have to be wavelength-scale smooth. Here we present the first experimental demonstration of a photonic delay line based on topologically protected surface electromagnetic waves (TPSWs) between two PTIs which are the EM counterparts of the quantum spin-Hall topological insulators in condensed matter. Unlike conventional guided EM waves that do not benefit from topological protection, TPSWs are shown to experience multi-wavelength reflection-free time delays when detoured around sharply-curved paths, thus offering a unique paradigm for compact and efficient wave buffers and other devices. PMID:27345575

Driving reconnection in sheared magnetic configurations with forced fluctuations

NASA Astrophysics Data System (ADS)

Pongkitiwanichakul, Peera; Makwana, Kirit D.; Ruffolo, David

2018-02-01

We investigate reconnection of magnetic field lines in sheared magnetic field configurations due to fluctuations driven by random forcing by means of numerical simulations. The simulations are performed with an incompressible, pseudo-spectral magnetohydrodynamics code in 2D where we take thick, resistively decaying, current-sheet like sheared magnetic configurations which do not reconnect spontaneously. We describe and test the forcing that is introduced in the momentum equation to drive fluctuations. It is found that the forcing does not change the rate of decay; however, it adds and removes energy faster in the presence of the magnetic shear structure compared to when it has decayed away. We observe that such a forcing can induce magnetic reconnection due to field line wandering leading to the formation of magnetic islands and O-points. These reconnecting field lines spread out as the current sheet decays with time. A semi-empirical formula is derived which reasonably explains the formation and spread of O-points. We find that reconnection spreads faster with stronger forcing and longer correlation time of forcing, while the wavenumber of forcing does not have a significant effect. When the field line wandering becomes large enough, the neighboring current sheets with opposite polarity start interacting, and then the magnetic field is rapidly annihilated. This work is useful to understand how forced fluctuations can drive reconnection in large scale current structures in space and astrophysical plasmas that are not susceptible to reconnection.

HOPE: An On-Line Piloted Handling Qualities Experiment Data Book

NASA Technical Reports Server (NTRS)

Jackson, E. B.; Proffitt, Melissa S.

2010-01-01

A novel on-line database for capturing most of the information obtained during piloted handling qualities experiments (either flight or simulated) is described. The Hyperlinked Overview of Piloted Evaluations (HOPE) web application is based on an open-source object-oriented Web-based front end (Ruby-on-Rails) that can be used with a variety of back-end relational database engines. The hyperlinked, on-line data book approach allows an easily-traversed way of looking at a variety of collected data, including pilot ratings, pilot information, vehicle and configuration characteristics, test maneuvers, and individual flight test cards and repeat runs. It allows for on-line retrieval of pilot comments, both audio and transcribed, as well as time history data retrieval and video playback. Pilot questionnaires are recorded as are pilot biographies. Simple statistics are calculated for each selected group of pilot ratings, allowing multiple ways to aggregate the data set (by pilot, by task, or by vehicle configuration, for example). Any number of per-run or per-task metrics can be captured in the database. The entire run metrics dataset can be downloaded in comma-separated text for further analysis off-line. It is expected that this tool will be made available upon request

Understanding the rotation of coronal holes

NASA Astrophysics Data System (ADS)

Wang, Y.-M.; Sheeley, N. R., Jr.

1993-09-01

In an earlier study we found that the rotation of coronal holes could be understood on the basis of a nearly current-free coronal field, with the holes representing open magnetic regions. In this paper we illustrate the model by focusing on the case of CH1, the rigidly rotating boot-shaped hole observed by Skylab. We show that the interaction between the polar fields and the flux associated with active regions produces distortions in the coronal field configuration and thus in the polar-hole boundaries; these distortions corotate with the perturbing nonaxisymmetric flux. In the case of CH1, positive-polarity field lines in the northern hemisphere 'collided' with like-polarity field lines fanning out from a decaying active region complex located just below the equator, producing a midlatitude corridor of open field lines rotating at the rate of the active region complex. Sheared coronal holes result when nonaxisymmetric flux is present at high latitudes, or equivalently, when the photospheric neutral line extends to high latitudes. We demonstrate how a small active region, rotating at the local photospheric rate, can drift through a rigidly rotating hole like CH1. Finally, we discuss the role of field-line reconnection in maintaining a quasi-potential coronal configuration.

Effect of vertical-tail location on the aerodynamic characteristics at subsonic speeds of a close-coupled canard configuration

NASA Technical Reports Server (NTRS)

Huffman, J. K.

1975-01-01

The effects were studied of various vertical-tail configurations on the longitudinal and lateral directional-stability characteristics of a general research fighter model utilizing wing-body-canard. The study indicates that the addition of the high canard resulted in an increase in total lift at angles of attack above 4 deg with a maximum lift coefficient about twice as large as that for the wing-body configuration. For the wing-body (canard off) configuration, the center-line vertical tail indicates positive vertical-tail effectiveness throughout the test angle-of-attack range; however, for this configuration none of the wing-mounted vertical-tail locations tested resulted in a positive directional-stability increment at the higher angles of attack. For the wing-body-canard configuration several outboard locations of the wing-mounted vertical tails were found.

Irradiation combined with SU5416: Microvascular changes and growth delay in a human xenograft glioblastoma tumor line

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

Schuuring, Janneke; Department of Neurology, Groene Hart Hospital, Gouda; Bussink, Johan

Purpose: The combination of irradiation and the antiangiogenic compound SU5416 was tested and compared with irradiation alone in a human glioblastoma tumor line xenografted in nude mice. The aim of this study was to monitor microenvironmental changes and growth delay. Methods and materials: A human glioblastoma xenograft tumor line was implanted in nude mice. Irradiations consisted of 10 Gy or 20 Gy with and without SU5416. Several microenvironmental parameters (tumor cell hypoxia, tumor blood perfusion, vascular volume, and microvascular density) were analyzed after imunohistochemical staining. Tumor growth delay was monitored for up to 200 days after treatment. Results: SU5416, whenmore » combined with irradiation, has an additive effect over treatment with irradiation alone. Analysis of the tumor microenvironment showed a decreased vascular density during treatment with SU5416. In tumors regrowing after reaching only a partial remission, vascular characteristics normalized shortly after cessation of SU5416. However, in tumors regrowing after reaching a complete remission, permanent microenvironmental changes and an increase of tumor necrosis with a subsequent slower tumor regrowth was found. Conclusions: Permanent vascular changes were seen after combined treatment resulting in complete remission. Antiangiogenic treatment with SU5416 when combined with irradiation has an additive effect over treatment with irradiation or antiangiogenic treatment alone.« less

Development of chipless, wireless current sensor system based on giant magnetoimpedance magnetic sensor and surface acoustic wave transponder.

PubMed

Kondalkar, Vijay V; Li, Xiang; Park, Ikmo; Yang, Sang Sik; Lee, Keekeun

2018-02-05

A chipless, wireless current sensor system was developed using a giant magnetoimpedance (GMI) magnetic sensor and one-port surface acoustic wave (SAW) reflective delay line for real-time power monitoring in a current-carrying conductor. The GMI sensor has a high-quality crystalline structure in each layer, which contributes to a high sensitivity and good linearity in a magnetic field of 3-16 Oe. A 400 MHz RF energy generated from the interdigital transducer (IDT)-type reflector on the one-port SAW delay line was used as an activation source for the GMI magnetic sensor. The one-port SAW delay line replaces the presently existing transceiver system, which is composed of thousands of transistors, thus enabling chipless and wireless operation. We confirmed a large variation in the amplitude of the SAW reflection peak with a change in the impedance of the GMI sensor caused by the current flow through the conductor. Good linearity and sensitivity of ~0.691 dB/A were observed for currents in the range 1-12 A. Coupling of Mode (COM) modeling and impedance matching analysis were also performed to predict the device performance in advance and these were compared with the experimental results.

ZRBA1, a Mixed EGFR/DNA Targeting Molecule, Potentiates Radiation Response Through Delayed DNA Damage Repair Process in a Triple Negative Breast Cancer Model

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

Heravi, Mitra; Department of Radiation Oncology, McGill University, Montreal; Segal Cancer Center, Jewish General Hospital, Montreal

2015-06-01

Purpose: ZRBA1 is a combi-molecule designed to induce DNA alkylating lesions and to block epidermal growth factor receptor (EGFR) TK domain. Inasmuch as ZRBA1 downregulates the EGFR TK-mediated antisurvival signaling and induces DNA damage, we postulated that it might be a radiosensitizer. The aim of this study was to further investigate the potentiating effect of ZRBA1 in combination with radiation and to elucidate the possible mechanisms of interaction between these 2 treatment modalities. Methods and Materials: The triple negative human breast MDA-MB-468 cancer cell line and mouse mammary cancer 4T1 cell line were used in this study. Clonogenic assay, Westernmore » blot analysis, and DNA damage analysis were performed at multiple time points after treatment. To confirm our in vitro findings, in vivo tumor growth delay assay was performed. Results: Our results show that a combination of ZRBA1 and radiation increases the radiation sensitivity of both cell lines significantly with a dose enhancement factor of 1.56, induces significant numbers of DNA strand breaks, prolongs higher DNA damage up to 24 hours after treatment, and significantly increases tumor growth delay in a syngeneic mouse model. Conclusions: Our data suggest that the higher efficacy of this combination could be partially due to increased DNA damage and delayed DNA repair process and to the inhibition of EGFR. The encouraging results of this combination demonstrated a significant improvement in treatment efficiency and therefore could be applicable in early clinical trial settings.« less

FE-XIII Infrared / FE-XIV Green Line Ratio Diagnostics (P55)

NASA Astrophysics Data System (ADS)

Srivastava, A. K.; et al.

2006-11-01

aks.astro.itbhu@gmail.com We consider the first 27-level atomic model of Fe XIII (5.9 < log Te < 6.4 K) to estimate its ground level populations, taking account of electron as well as proton collisional excitations and de-excitations, radiative cascades, radiative excitations and de-excitations. Radiative cascade is important but the effect of dilution factor is negligible at higher electron densities. The 3 P1-3P0 and 3P2-3P1 transitions in the ground configuration 3s2 3p2 of Fe XIII result in two forbidden coronal emission lines in the infrared region, namely 10747 Å and 10798 Å., while the 5303 Å green line is formed in the 3s2 3p 2 2 ground configuration of Fe XIV as a result of P3 / 2 - P1 / 2 magnetic dipole transition. The line-widths of appropriate pair of forbidden coronal emission lines observed simultaneously can be useful diagnostic tool to deduce temperature and non-thermal velocity in the large scale coronal structures using intensity ratios of the lines as the temperature signature, instead of assuming ion temperature to be equal to the electron temperature. Since the line intensity ratios IG5303/IIR10747 and IG5303/IIR10798 have very week density dependence, they are ideal monitors of temperature mapping in the solar corona.

Relativistic features and time delay of laser-induced tunnel ionization

NASA Astrophysics Data System (ADS)

Yakaboylu, Enderalp; Klaiber, Michael; Bauke, Heiko; Hatsagortsyan, Karen Z.; Keitel, Christoph H.

2013-12-01

The electron dynamics in the classically forbidden region during relativistic tunnel ionization is investigated. The classical forbidden region in the relativistic regime is identified by defining a gauge-invariant total-energy operator. Introducing position-dependent energy levels inside the tunneling barrier, we demonstrate that the relativistic tunnel ionization can be well described by a one-dimensional intuitive picture. This picture predicts that, in contrast to the well-known nonrelativistic regime, the ionized electron wave packet arises with a momentum shift along the laser's propagation direction. This is compatible with results from a strong-field approximation calculation where the binding potential is assumed to be zero ranged. Further, the tunneling time delay, stemming from Wigner's definition, is investigated for model configurations of tunneling and compared with results obtained from the exact propagator. By adapting Wigner's time delay definition to the ionization process, the tunneling time is investigated in the deep-tunneling and in the near-threshold-tunneling regimes. It is shown that while in the deep-tunneling regime signatures of the tunneling time delay are not measurable at remote distance, they are detectable, however, in the latter regime.

A Never-Get-Lost Reading Program

ERIC Educational Resources Information Center

Moore, William

2010-01-01

This paper proposes a reading support technique for Arabic students of English. These students must overcome the L1 interference "reversal of reading direction." PowerPoint presentations, utilizing a simple fade effect with adjustable delay between words such that the text appears nicely in a left-to-right manner, line by line with voice…

Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei XVI: A 13 Year Study of Spectral Variability in NGC 5548

NASA Technical Reports Server (NTRS)

Peterson, B. M.; Berlind, P.; Bertram, R.; Bischoff, K.; Bochkarev, N. G.; Burenkov, A. N.; Calkins, M.; Carrasco, L.; Chavushyan, V. H.

2002-01-01

We present the final installment of an intensive 13 year study of variations of the optical continuum and broad H beta emission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 H beta measurements. The H beta variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction between the size of the broad-line region and the ionizing luminosity, r is proportional to L(sup 1/2)(sub ion). Moreover, the apparently linear nature of the correlation between the H beta response time and the nonstellar optical continuum F(sub opt) arises as a consequence of the changing shape of the continuum as it varies, specifically F(sub opt) is proportional to F(sup 0.56)(sub UV).

Alterations of mitochondrial DNA in CEM cells selected for resistance toward ddC toxicity.

PubMed

Bjerke, M; Franco, M; Johansson, M; Balzarini, J; Karlsson, A

2006-01-01

2 ',3 '-dideoxycytidine (ddC) is a nucleoside analog that has been shown to produce a delayed toxicity which may be due to the depletion of mitochondrial DNA (mtDNA). In order to gain further understanding of the events involved in mitochondrial toxicity, two different CEM cell lines were selected for resistance to the delayed ddC toxicity.

A loose bolt delays loading of Endeavour's external tank

NASA Technical Reports Server (NTRS)

2000-01-01

This loose bracket, observed hanging down from the side of the White Room at Launch Pad 39B, delayed loading of Endeavour's external tank by several hours to allow technicians to remove it. A 'U' bolt connects the bracket to a fire suppression water line attached to the exterior of the White Room. The loose bolt could have possibly created a debris hazard.

Aerodynamics of an Axisymmetric Missile Concept Having Cruciform Strakes and In-Line Tail Fins From Mach 0.60 to 4.63

NASA Technical Reports Server (NTRS)

Allen, Jerry M.

2005-01-01

An experimental study has been performed to develop a large force and moment aerodynamic data set on a slender axisymmetric missile configuration having cruciform strakes and in-line control tail fins. The data include six-component balance measurements of the configuration aerodynamics and three-component measurements on all four tail fins. The test variables include angle of attack, roll angle, Mach number, model buildup, strake length, nose size, and tail fin deflection angles to provide pitch, yaw, and roll control. Test Mach numbers ranged from 0.60 to 4.63. The entire data set is presented on a CD-ROM that is attached to this paper. The CD-ROM also includes extensive plots of both the six-component configuration data and the three-component tail fin data. Selected samples of these plots are presented in this paper to illustrate the features of the data and to investigate the effects of the test variables.

Aerodynamics of an Axisymmetric Missile Concept Having Cruciform Strakes and In-Line Tail Fins From Mach 0.60 to 4.63, Supplement

NASA Technical Reports Server (NTRS)

Allen, Jerry M.

2005-01-01

An experimental study has been performed to develop a large force and moment aerodynamic data set on a slender axisymmetric missile configuration having cruciform strakes and in-line control tail fins. The data include six-component balance measurements of the configuration aerodynamics and three-component measurements on all four tail fins. The test variables include angle of attack, roll angle, Mach number, model buildup, strake length, nose size, and tail fin deflection angles to provide pitch, yaw, and roll control. Test Mach numbers ranged from 0.60 to 4.63. The entire data set is presented on a CD-ROM that is attached to this paper. The CD-ROM also includes extensive plots of both the six-component configuration data and the three-component tail fin data. Selected samples of these plots are presented in this paper to illustrate the features of the data and to investigate the effects of the test variables.

Hyperfine Structure Constants of Energetically High-lying Levels of Odd Parity of Atomic Vanadium

NASA Astrophysics Data System (ADS)

Güzelçimen, F.; Yapıcı, B.; Demir, G.; Er, A.; Öztürk, I. K.; Başar, Gö.; Kröger, S.; Tamanis, M.; Ferber, R.; Docenko, D.; Başar, Gü.

2014-09-01

High-resolution Fourier transform spectra of a vanadium-argon plasma have been recorded in the wavelength range of 365-670 nm (15,000-27,400 cm-1). Optical bandpass filters were used in the experimental setup to enhance the sensitivity of the Fourier transform spectrometer. In total, 138 atomic vanadium spectral lines showing resolved or partially resolved hyperfine structure have been analyzed to determine the magnetic dipole hyperfine structure constants A of the involved energy levels. One of the investigated lines has not been previously classified. As a result, the magnetic dipole hyperfine structure constants A for 90 energy levels are presented: 35 of them belong to the configuration 3d 34s4p and 55 to the configuration 3d 44p. Of these 90 constants, 67 have been determined for the first time, with 23 corresponding to the configuration 3d 34s4p and 44 to 3d 44p.

Delamination and Stitched Failure in Stitched Composite Joints

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1999-01-01

The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and finite element study. The experimental program was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation of the debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The experimentally determined debond length vs. applied load was used as an input parameter in the finite element analysis of both configurations. The strain energy release rates at the debond from were calculated using plate finite elements. Nonlinear fastener elements were used to model the stitches and multipoint constraints were used to model the contact problem. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches were effective in reducing mode I to zero, but had less of an effect on modes II and III.

Numerical Analysis of the SCHOLAR Supersonic Combustor

NASA Technical Reports Server (NTRS)

Rodriguez, Carlos G.; Cutler, Andrew D.

2003-01-01

The SCHOLAR scramjet experiment is the subject of an ongoing numerical investigation. The facility nozzle and combustor were solved separate and sequentially, with the exit conditions of the former used as inlet conditions for the latter. A baseline configuration for the numerical model was compared with the available experimental data. It was found that ignition-delay was underpredicted and fuel-plume penetration overpredicted, while the pressure rise was close to experimental values. In addition, grid-convergence by means of grid-sequencing could not be established. The effects of the different turbulence parameters were quantified. It was found that it was not possible to simultaneously predict the three main parameters of this flow: pressure-rise, ignition-delay, and fuel-plume penetration.

Controllability of multi-agent systems with time-delay in state and switching topology

NASA Astrophysics Data System (ADS)

Ji, Zhijian; Wang, Zidong; Lin, Hai; Wang, Zhen

2010-02-01

In this article, the controllability issue is addressed for an interconnected system of multiple agents. The network associated with the system is of the leader-follower structure with some agents taking leader role and others being followers interconnected via the neighbour-based rule. Sufficient conditions are derived for the controllability of multi-agent systems with time-delay in state, as well as a graph-based uncontrollability topology structure is revealed. Both single and double integrator dynamics are considered. For switching topology, two algebraic necessary and sufficient conditions are derived for the controllability of multi-agent systems. Several examples are also presented to illustrate how to control the system to shape into the desired configurations.

Delayed flap approach procedures for noise abatement and fuel conservation

NASA Technical Reports Server (NTRS)

Edwards, F. G.; Bull, J. S.; Foster, J. D.; Hegarty, D. M.; Drinkwater, F. J., III

1976-01-01

The NASA/Ames Research Center is currently investigating the delayed flap approach during which pilot actions are determined and prescribed by an onboard digital computer. The onboard digital computer determines the proper timing for the deployment of the landing gear and flaps based on the existing winds and airplane gross weight. Advisory commands are displayed to the pilot. The approach is flown along the conventional ILS glide slope but is initiated at a higher airspeed and in a clean aircraft configuration that allows for low thrust and results in reduced noise and fuel consumption. Topics discussed include operational procedures, pilot acceptability of these procedures, and fuel/noise benefits resulting from flight tests and simulation.

Using Crowdsourcing to Examine Relations Between Delay and Probability Discounting

PubMed Central

Jarmolowicz, David P.; Bickel, Warren K.; Carter, Anne E.; Franck, Christopher T.; Mueller, E. Terry

2016-01-01

Although the extensive lines of research on delay and/or probability discounting have greatly expanded our understanding of human decision-making processes, the relation between these two phenomena remains unclear. For example, some studies have reported robust associations between delay and probability discounting, whereas others have failed to demonstrate a consistent relation between the two. The current study sought to clarify this relation by examining the relation between delay and probability discounting in a large sample of internet users (n= 904) using the Amazon Mechanical Turk (AMT) crowdsourcing service. Because AMT is a novel data collection platform, the findings were validated through the replication of a number of previously established relations (e.g., relations between delay discounting and cigarette smoking status). A small but highly significant positive correlation between delay and probability discounting rates was obtained, and principal component analysis suggested that two (rather than one) components were preferable to account for the variance in both delay and probability discounting. Taken together, these findings suggest that delay and probability discounting may be related, but are not manifestations of a single component (e.g., impulsivity). PMID:22982370

Automatic toilet seat lowering apparatus

DOEpatents

Guerty, Harold G.

1994-09-06

A toilet seat lowering apparatus includes a housing defining an internal cavity for receiving water from the water supply line to the toilet holding tank. A descent delay assembly of the apparatus can include a stationary dam member and a rotating dam member for dividing the internal cavity into an inlet chamber and an outlet chamber and controlling the intake and evacuation of water in a delayed fashion. A descent initiator is activated when the internal cavity is filled with pressurized water and automatically begins the lowering of the toilet seat from its upright position, which lowering is also controlled by the descent delay assembly. In an alternative embodiment, the descent initiator and the descent delay assembly can be combined in a piston linked to the rotating dam member and provided with a water channel for creating a resisting pressure to the advancing piston and thereby slowing the associated descent of the toilet seat. A toilet seat lowering apparatus includes a housing defining an internal cavity for receiving water from the water supply line to the toilet holding tank. A descent delay assembly of the apparatus can include a stationary dam member and a rotating dam member for dividing the internal cavity into an inlet chamber and an outlet chamber and controlling the intake and evacuation of water in a delayed fashion. A descent initiator is activated when the internal cavity is filled with pressurized water and automatically begins the lowering of the toilet seat from its upright position, which lowering is also controlled by the descent delay assembly. In an alternative embodiment, the descent initiator and the descent delay assembly can be combined in a piston linked to the rotating dam member and provided with a water channel for creating a resisting pressure to the advancing piston and thereby slowing the associated descent of the toilet seat.

Teaching Reflections about the Architectural Design of the Vocational Training Centers in Granada

ERIC Educational Resources Information Center

Rodríguez, Luis; Gallego, José L.; Rodríguez, Antonio V.

2016-01-01

If the specificity of the architectural space is considered as a measuring element in the education scope to value the prominence of teaching throughout history, it is worth mentioning that the configuration of the vocational training center as a first-rate education scenario that arrives half century of delay with respect to schools, has few…

A Generalised Fault Protection Structure Proposed for Uni-grounded Low-Voltage AC Microgrids

NASA Astrophysics Data System (ADS)

Bui, Duong Minh; Chen, Shi-Lin; Lien, Keng-Yu; Jiang, Jheng-Lun

2016-04-01

This paper presents three main configurations of uni-grounded low-voltage AC microgrids. Transient situations of a uni-grounded low-voltage (LV) AC microgrid (MG) are simulated through various fault tests and operation transition tests between grid-connected and islanded modes. Based on transient simulation results, available fault protection methods are proposed for main and back-up protection of a uni-grounded AC microgrid. In addition, concept of a generalised fault protection structure of uni-grounded LVAC MGs is mentioned in the paper. As a result, main contributions of the paper are: (i) definition of different uni-grounded LVAC MG configurations; (ii) analysing transient responses of a uni-grounded LVAC microgrid through line-to-line faults, line-to-ground faults, three-phase faults and a microgrid operation transition test, (iii) proposing available fault protection methods for uni-grounded microgrids, such as: non-directional or directional overcurrent protection, under/over voltage protection, differential current protection, voltage-restrained overcurrent protection, and other fault protection principles not based on phase currents and voltages (e.g. total harmonic distortion detection of currents and voltages, using sequence components of current and voltage, 3I0 or 3V0 components), and (iv) developing a generalised fault protection structure with six individual protection zones to be suitable for different uni-grounded AC MG configurations.

Effect of flow rate and lead/copper pipe sequence on lead release from service lines.

PubMed

Cartier, Clément; Arnold, Roger B; Triantafyllidou, Simoni; Prévost, Michèle; Edwards, Marc

2012-09-01

A pilot experiment examined lead leaching from four representative configurations of service lines including: (1) 100% lead (Pb), (2) 100% copper (Cu), (3) 50% Pb upstream of 50% Cu, and (4) 50% Pb-downstream of 50% Cu using a range of flow rates. The cumulative mass of lead release indicated that a typical partial replacement configuration (50% lead downstream of copper) did not provide a net reduction in lead when compared to 100% lead pipe (85 mg for 50% Pb-downstream versus 83 mg for 100%-Pb) due to galvanic and deposition corrosion. The partially replaced service line configuration also had a much greater likelihood of producing water with "spikes" of lead particulates at higher flow rates, while tending to produce lower levels of lead at very low flow rates. After the first 214 days the galvanic current between copper and lead was only reduced by 34%, proving that galvanic impacts can be highly persistent even in water with optimized corrosion control by dosing of zinc orthophosphate. Finally, this experiment raises concern about the low flow rates used during some prior home sampling events, which may underestimate exposure to lead during normal water use, especially when galvanic Pb:Cu connections are present. Copyright © 2012 Elsevier Ltd. All rights reserved.

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

PubMed Central

Gan, Lin; Li, Xianglong; Cai, Xinyi; Liu, Kunkun; Li, Wei

2018-01-01

The design of orange-light emitting, thermally activated, delayed fluorescence (TADF) materials is necessary and important for the development and application of organic light-emitting diodes (OLEDs). Herein, two donor–acceptor–donor (D–A–D)-type orange TADF materials based on fluorenone and acridine, namely 2,7-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (27DACRFT, 1) and 3,6-bis(9,9-dimethylacridin-10(9H)-yl)-9H-fluoren-9-one (36DACRFT, 2), were successfully synthetized and characterized. The studies on their structure–property relationship show that the different configurations have a serious effect on the photoluminescence and electroluminescence performance according to the change in singlet–triplet splitting energy (ΔE ST) and excited state geometry. This indicates that a better configuration design can reduce internal conversion and improve triplet exciton utilization of TADF materials. Importantly, OLEDs based on 2 exhibited a maximum external quantum efficiency of 8.9%, which is higher than the theoretical efficiency of the OLEDs based on conventional fluorescent materials. PMID:29623130

Effect of organizational strategy on visual memory in patients with schizophrenia.

PubMed

Kim, Myung-Sun; Namgoong, Yoon; Youn, Tak

2008-08-01

The aim of the present study was to examine how copy organization mediated immediate recall among patients with schizophrenia using the Rey-Osterrieth Complex Figure Test (ROCF). The Boston Qualitative Scoring System (BQSS) was applied for qualitative and quantitative analyses of ROCF performances. Subjects included 20 patients with schizophrenia and 20 age- and gender-matched healthy controls. During the copy condition, the schizophrenia group and the control group differed in fragmentation; during the immediate recall condition, the two groups differed in configural presence and planning; and during the delayed recall condition, they differed in several qualitative measurements, including configural presence, cluster presence/placement, detail presence/placement, fragmentation, planning, and neatness. The two groups also differed in several quantitative measurements, including immediate presence and accuracy, immediate retention, delayed retention, and organization. Although organizational strategies used during the copy condition mediated the difference between the two groups during the immediate recall condition, group also had a significant direct effect on immediate recall. Schizophrenia patients are deficient in visual memory, and a piecemeal approach to the figure and organizational deficit seem to be related to the visual memory deficit. But schizophrenia patients also appeared to have some memory problems, including retention and/or retrieval deficits.

Laser-induced periodic surface structures on titanium upon single- and two-color femtosecond double-pulse irradiation.

PubMed

Höhm, Sandra; Rosenfeld, Arkadi; Krüger, Jörg; Bonse, Jörn

2015-10-05

Single- and two-color double-fs-pulse experiments were performed on titanium to study the dynamics of the formation of laser-induced periodic surface structures (LIPSS). A Mach-Zehnder inter-ferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences in two configurations - either at 800 nm only, or at 400 and 800 nm wavelengths. The inter-pulse delays of the individual 50-fs pulses ranged up to some tens of picoseconds. Multiple of these single- or two-color double-fs-pulse sequences were collinearly focused by a spherical mirror to the sample surface. In both experimental configurations, the peak fluence of each individual pulse was kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics were analyzed by scanning electron microscopy and the periods were quantified by Fourier analyses. The LIPSS periods along with the orientation allow a clear identification of the pulse which dominates the energy coupling to the material. A plasmonic model successfully explains the delay-dependence of the LIPSS on titanium and confirms the importance of the ultrafast energy deposition stage for LIPSS formation.

Optimization of locations of diffusion spots in indoor optical wireless local area networks

NASA Astrophysics Data System (ADS)

Eltokhey, Mahmoud W.; Mahmoud, K. R.; Ghassemlooy, Zabih; Obayya, Salah S. A.

2018-03-01

In this paper, we present a novel optimization of the locations of the diffusion spots in indoor optical wireless local area networks, based on the central force optimization (CFO) scheme. The users' performance uniformity is addressed by using the CFO algorithm, and adopting different objective function's configurations, while considering maximization and minimization of the signal to noise ratio and the delay spread, respectively. We also investigate the effect of varying the objective function's weights on the system and the users' performance as part of the adaptation process. The results show that the proposed objective function configuration-based optimization procedure offers an improvement of 65% in the standard deviation of individual receivers' performance.

Juncture flow improvement for wing/pylon configurations by using CFD methodology

NASA Technical Reports Server (NTRS)

Gea, Lie-Mine; Chyu, Wei J.; Stortz, Michael W.; Chow, Chuen-Yen

1993-01-01

Transonic flow field around a fighter wing/pylon configuration was simulated by using an implicit upwinding Navier-Stokes flow solver (F3D) and overset grid technology (Chimera). Flow separation and local shocks near the wing/pylon junction were observed in flight and predicted by numerical calculations. A new pylon/fairing shape was proposed to improve the flow quality. Based on numerical results, the size of separation area is significantly reduced and the onset of separation is delayed farther downstream. A smoother pressure gradient is also obtained near the junction area. This paper demonstrates that computational fluid dynamics (CFD) methodology can be used as a practical tool for aircraft design.

Two-dimensional Imaging Velocity Interferometry: Technique and Data Analysis

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

Erskine, D J; Smith, R F; Bolme, C

2011-03-23

We describe the data analysis procedures for an emerging interferometric technique for measuring motion across a two-dimensional image at a moment in time, i.e. a snapshot 2d-VISAR. Velocity interferometers (VISAR) measuring target motion to high precision have been an important diagnostic in shockwave physics for many years Until recently, this diagnostic has been limited to measuring motion at points or lines across a target. We introduce an emerging interferometric technique for measuring motion across a two-dimensional image, which could be called a snapshot 2d-VISAR. If a sufficiently fast movie camera technology existed, it could be placed behind a traditional VISARmore » optical system and record a 2d image vs time. But since that technology is not yet available, we use a CCD detector to record a single 2d image, with the pulsed nature of the illumination providing the time resolution. Consequently, since we are using pulsed illumination having a coherence length shorter than the VISAR interferometer delay ({approx}0.1 ns), we must use the white light velocimetry configuration to produce fringes with significant visibility. In this scheme, two interferometers (illuminating, detecting) having nearly identical delays are used in series, with one before the target and one after. This produces fringes with at most 50% visibility, but otherwise has the same fringe shift per target motion of a traditional VISAR. The 2d-VISAR observes a new world of information about shock behavior not readily accessible by traditional point or 1d-VISARS, simultaneously providing both a velocity map and an 'ordinary' snapshot photograph of the target. The 2d-VISAR has been used to observe nonuniformities in NIF related targets (polycrystalline diamond, Be), and in Si and Al.« less

Electromagnetic field therapy delays cellular senescence and death by enhancement of the heat shock response.

PubMed

Perez, Felipe P; Zhou, Ximing; Morisaki, Jorge; Jurivich, Donald

2008-04-01

Hormesis may result when mild repetitive stress increases cellular defense against diverse injuries. This process may also extend in vitro cellular proliferative life span as well as delay and reverse some of the age-dependent changes in both replicative and non-replicative cells. This study evaluated the potential hormetic effect of non-thermal repetitive electromagnetic field shock (REMFS) and its impact on cellular aging and mortality in primary human T lymphocytes and fibroblast cell lines. Unlike previous reports employing electromagnetic radiation, this study used a long wave length, low energy, and non-thermal REMFS (50MHz/0.5W) for various therapeutic regimens. The primary outcomes examined were age-dependent morphological changes in cells over time, cellular death prevention, and stimulation of the heat shock response. REMFS achieved several biological effects that modified the aging process. REMFS extended the total number of population doublings of mouse fibroblasts and contributed to youthful morphology of cells near their replicative lifespan. REMFS also enhanced cellular defenses of human T cells as reflected in lower cell mortality when compared to non-treated T cells. To determine the mechanism of REMFS-induced effects, analysis of the cellular heat shock response revealed Hsp90 release from the heat shock transcription factor (HSF1). Furthermore, REMFS increased HSF1 phosphorylation, enhanced HSF1-DNA binding, and improved Hsp70 expression relative to non-REMFS-treated cells. These results show that non-thermal REMFS activates an anti-aging hormetic effect as well as reduces cell mortality during lethal stress. Because the REMFS configuration employed in this study can potentially be applied to whole body therapy, prospects for translating these data into clinical interventions for Alzheimer's disease and other degenerative conditions with aging are discussed.

Surface and subsurface inspection of food safety and quality using a line-scan Raman system

USDA-ARS?s Scientific Manuscript database

This paper presents a line-scan Raman platform for food safety and quality research, which can be configured for Raman chemical imaging (RCI) mode for surface inspection and spatially offset Raman spectroscopy (SORS) mode for subsurface inspection. In the RCI mode, macro-scale imaging was achieved u...

40 CFR 63.148 - Leak inspection provisions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... line; or (2) Secure the bypass line valve in the closed position with a car-seal or a lock-and-key type... configuration has been checked out, and records of any car-seal that has broken. (4) For each inspection during...

40 CFR 63.148 - Leak inspection provisions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... line; or (2) Secure the bypass line valve in the closed position with a car-seal or a lock-and-key type... configuration has been checked out, and records of any car-seal that has broken. (4) For each inspection during...

40 CFR 63.148 - Leak inspection provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... line; or (2) Secure the bypass line valve in the closed position with a car-seal or a lock-and-key type... configuration has been checked out, and records of any car-seal that has broken. (4) For each inspection during...

40 CFR 63.148 - Leak inspection provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Standards for Organic Hazardous Air Pollutants From the Synthetic Organic Chemical Manufacturing Industry... line; or (2) Secure the bypass line valve in the closed position with a car-seal or a lock-and-key type... configuration has been checked out, and records of any car-seal that has broken. (4) For each inspection during...

Line-scan Raman imaging and spectroscopy platform for surface and subsurface evaluation of food safety and quality

USDA-ARS?s Scientific Manuscript database

Both surface and subsurface food inspection is important since interesting safety and quality attributes can be at different sample locations. This paper presents a multipurpose line-scan Raman platform for food safety and quality research, which can be configured for Raman chemical imaging (RCI) mo...

Assessment of Preconditioner for a USM3D Hierarchical Adaptive Nonlinear Method (HANIM) (Invited)

NASA Technical Reports Server (NTRS)

Pandya, Mohagna J.; Diskin, Boris; Thomas, James L.; Frink, Neal T.

2016-01-01

Enhancements to the previously reported mixed-element USM3D Hierarchical Adaptive Nonlinear Iteration Method (HANIM) framework have been made to further improve robustness, efficiency, and accuracy of computational fluid dynamic simulations. The key enhancements include a multi-color line-implicit preconditioner, a discretely consistent symmetry boundary condition, and a line-mapping method for the turbulence source term discretization. The USM3D iterative convergence for the turbulent flows is assessed on four configurations. The configurations include a two-dimensional (2D) bump-in-channel, the 2D NACA 0012 airfoil, a three-dimensional (3D) bump-in-channel, and a 3D hemisphere cylinder. The Reynolds Averaged Navier Stokes (RANS) solutions have been obtained using a Spalart-Allmaras turbulence model and families of uniformly refined nested grids. Two types of HANIM solutions using line- and point-implicit preconditioners have been computed. Additional solutions using the point-implicit preconditioner alone (PA) method that broadly represents the baseline solver technology have also been computed. The line-implicit HANIM shows superior iterative convergence in most cases with progressively increasing benefits on finer grids.

Differential acceleration in the final beam lines of a Heavy Ion Fusion driver

DOE PAGES

Friedman, Alex

2013-10-19

A long-standing challenge in the design of a Heavy Ion Fusion power plant is that the ion beams entering the target chamber, which number of order a hundred, all need to be routed from one or two multi-beam accelerators through a set of transport lines. The beams are divided into groups, which each have unique arrival times and may have unique kinetic energies. It is also necessary to arrange for each beam to enter the target chamber from a prescribed location on the periphery of that chamber. Furthermore, it has generally been assumed that additional constraints must be obeyed: thatmore » the path lengths of the beams in a group must be equal, and that any delay of \\main-pulse" beams relative to \\foot-pulse" beams must be provided by the insertion of large delay-arcs in the main beam transport lines. Here we introduce the notion of applying \\di erential acceleration" to individual beams or sets of beam at strategic stages of the transport lines. That is, by accelerating some beams \\sooner" and others \\later," it is possible to simplify the beam line con guration in a number of cases. For example, the time delay between the foot and main pulses can be generated without resorting to large arcs in the main-pulse beam lines. It is also possible to use di erential acceleration to e ect the simultaneous arrival on target of a set of beams ( e.g., for the foot-pulse) without requiring that their path lengths be precisely equal. We illustrate the technique for two model con gurations, one corresponding to a typical indirect-drive scenario requiring distinct foot and main energies, and the other to an ion-driven fast-ignition scenario wherein the foot and main beams share a common energy.« less

Meniscal tears missed on MR imaging: relationship to meniscal tear patterns and anterior cruciate ligament tears.

PubMed

De Smet, A A; Graf, B K

1994-04-01

MR imaging of the knee is a valuable technique for diagnosing meniscal tears, but some tears found at arthroscopy are not shown on MR imaging. The purpose of this study was to determine whether or not tears were more frequently missed in the presence of an anterior cruciate ligament tear or when tears had certain locations or configurations. We reviewed the original MR reports and surgical records of 400 patients who had both an MR examination and arthroscopy of the knee. Using chi 2 analysis, we examined how the sensitivity for detecting meniscal tears varied with the presence of a tear of the anterior cruciate ligament, with the location of the tear within the meniscus, and among six configurations of meniscal tears. We also studied whether sensitivity decreased with an increasing delay between MR examination and arthroscopy. In the presence of a tear of the anterior cruciate ligament, the sensitivity decreased from 0.97 to 0.88 (p = .016) for medial meniscal tears and from 0.94 to 0.69 (p = .0005) for lateral tears. The overall sensitivity for lateral meniscal tears was significantly less for posterior (p = .001) and peripheral (p = .005) tears than for other tear locations or configurations. The sensitivities did not significantly differ between tear locations and configurations in the medial meniscus or with an increasing delay until arthroscopy. Patients with a torn anterior cruciate ligament were more likely to have peripheral tears of the medial meniscus (p = .00004) and posterior (p = .0004) and peripheral (p = .04) tears of the lateral meniscus. Because of their location and configuration, meniscal tears associated with an anterior cruciate ligament injury are more difficult to detect on MR images than are tears in knees with an intact ligament. If a tear of the anterior cruciate ligament is detected, special attention should be given to the subtle peripheral tears that may be present in either meniscus, but most commonly in the posterior horn of the lateral meniscus. These tears are especially difficult to detect on MR images.

Method for wiring allocation and switch configuration in a multiprocessor environment

DOEpatents

Aridor, Yariv [Zichron Ya'akov, IL; Domany, Tamar [Kiryat Tivon, IL; Frachtenberg, Eitan [Jerusalem, IL; Gal, Yoav [Haifa, IL; Shmueli, Edi [Haifa, IL; Stockmeyer, legal representative, Robert E.; Stockmeyer, Larry Joseph [San Jose, CA

2008-07-15

A method for wiring allocation and switch configuration in a multiprocessor computer, the method including employing depth-first tree traversal to determine a plurality of paths among a plurality of processing elements allocated to a job along a plurality of switches and wires in a plurality of D-lines, and selecting one of the paths in accordance with at least one selection criterion.

Injector for use in high voltage isolators for liquid feed lines

NASA Technical Reports Server (NTRS)

Snyder, J. A. (Inventor)

1973-01-01

An improved injector is described for use in introducing fluid substances into feed lines employed in delivering flowing bodies of liquids. The injector includes a porous plug, concentrically related to a feed line, including an internally tapered surface of a truncated conical configuration with an inlet orifice of a first diameter substantially smaller than the first diameter and an external surface circumscribed by an annular chamber containing a body of insulating gas.

Design of MOEMS adjustable optical delay line to reduce link set-up time in a tera-bit/s optical interconnection network.

PubMed

Jing, Wencai; Zhang, Yimo; Zhou, Ge

2002-07-15

A new structure for bit synchronization in a tera-bit/s optical interconnection network has been designed using micro-electro-mechanical system (MEMS) technique. Link multiplexing has been adopted to reduce data packet communication latency. To eliminate link set-up time, adjustable optical delay lines (AODLs) have been adopted to shift the phases of the distributed optical clock signals for bit synchronization. By changing the optical path distance of the optical clock signal, the phase of the clock signal can be shifted at a very high resolution. A phase-shift resolution of 0.1 ps can be easily achieved with 30-microm alternation of the optical path length in vacuum.

Implementation of Nonlinear Control Laws for an Optical Delay Line

NASA Technical Reports Server (NTRS)

Hench, John J.; Lurie, Boris; Grogan, Robert; Johnson, Richard

2000-01-01

This paper discusses the implementation of a globally stable nonlinear controller algorithm for the Real-Time Interferometer Control System Testbed (RICST) brassboard optical delay line (ODL) developed for the Interferometry Technology Program at the Jet Propulsion Laboratory. The control methodology essentially employs loop shaping to implement linear control laws. while utilizing nonlinear elements as means of ameliorating the effects of actuator saturation in its coarse, main, and vernier stages. The linear controllers were implemented as high-order digital filters and were designed using Bode integral techniques to determine the loop shape. The nonlinear techniques encompass the areas of exact linearization, anti-windup control, nonlinear rate limiting and modal control. Details of the design procedure are given as well as data from the actual mechanism.