The dynamic time-over-threshold method for multi-channel APD based gamma-ray detectors

Energy Technology Data Exchange (ETDEWEB)

Orita, T., E-mail: orita.tadashi@jaea.go.jp [Japan Atomic Energy Agency, Fukushima (Japan); Shimazoe, K.; Takahashi, H. [Department of Nuclear Management and Engineering, The University of Tokyo, Bunkyō (Japan)

2015-03-01

t– Recent advances in manufacturing technology have enabled the use of multi-channel pixelated detectors in gamma-ray imaging applications. When obtaining gamma-ray measurements, it is important to obtain pulse height information in order to avoid unnecessary events such as scattering. However, as the number of channels increases, more electronics are needed to process each channel's signal, and the corresponding increases in circuit size and power consumption can result in practical problems. The time-over-threshold (ToT) method, which has recently become popular in the medical field, is a signal processing technique that can effectively avoid such problems. However, ToT suffers from poor linearity and its dynamic range is limited. We therefore propose a new ToT technique called the dynamic time-over-threshold (dToT) method [4]. A new signal processing system using dToT and CR-RC shaping demonstrated much better linearity than that of a conventional ToT. Using a test circuit with a new Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (GAGG) scintillator and an avalanche photodiode, the pulse height spectra of {sup 137}Cs and {sup 22}Na sources were measured with high linearity. Based on these results, we designed a new application-specific integrated circuit (ASIC) for this multi-channel dToT system, measured the spectra of a {sup 22}Na source, and investigated the linearity of the system.

Data processing for the multichannel pulse height analysis system ND-50/50, (1)

International Nuclear Information System (INIS)

Katagiri, Masaki

1977-03-01

The multichannel pulse height analysis system ND-50/50 manufactured by Nuclear Data Inc. consists of a 4096 channel pulse height analyzer and a small computer PDP-8/L (Digital Equipment Corporation). A conversational interpretive language, MACAL (Multichannel Analyzer CALculator) has been developed to analyze gamma-ray spectra in ND-50/50. It is a modification of the FOCAL (FOrmula CALculator) language of Digital Equipment Corporation. MACAL consists of imperative English commands and mathematical expressions, and has standard mathematical functions and functions for controlling the multichannel pulse height analyzer and I/O devices (high-speed reader, high-speed punch, and digital plotter). With MACAL, the following five programs were prepared : 1) program for controlling the multichannel pulse height analyzer and data handling, 2) program for automatically analyzing gamma-ray spectra obtained by germanium detectors, 3) program for automatically measuring characteristics of germanium detectors, 4) program for calculating the center energy of gamma-ray peaks, and 5) program for plotting the pulse height distribution and diagraming the results obtained with the programs. By combining the programs according to experimental purposes, the system can be highly effective. (auth.)

Pulse width and height modulation for multi-level resistance in bi-layer TaOx based RRAM

Science.gov (United States)

Alamgir, Zahiruddin; Beckmann, Karsten; Holt, Joshua; Cady, Nathaniel C.

2017-08-01

Mutli-level switching in resistive memory devices enables a wide range of computational paradigms, including neuromorphic and cognitive computing. To this end, we have developed a bi-layer tantalum oxide based resistive random access memory device using Hf as the oxygen exchange layer. Multiple, discrete resistance levels were achieved by modulating the RESET pulse width and height, ranging from 2 kΩ to several MΩ. For a fixed pulse height, OFF state resistance was found to increase gradually with the increase in the pulse width, whereas for a fixed pulse width, the increase in the pulse height resulted in drastic changes in resistance. Resistive switching in these devices transitioned from Schottky emission in the OFF state to tunneling based conduction in the ON state, based on I-V curve fitting and temperature dependent current measurements. These devices also demonstrated endurance of more than 108 cycles with a satisfactory Roff/Ron ratio and retention greater than 104 s.

Pulse height non-linearity in LaBr3:Ce crystal for gamma ray spectrometry and imaging

International Nuclear Information System (INIS)

Pani, R.; Cinti, M.N.; Pellegrini, R.; Bennati, P.; Ridolfi, S.; Scafe, R.; Orsolini Cencelli, V.; De Notaristefani, F.; Fabbri, A.; Navarria, F.L.; Lanconelli, N.; Moschini, G.; Boccaccio, P.

2011-01-01

In this paper the response in term of pulse height linearity of two Hamamatsu photomultipliers is investigated, when coupled to a LaBr 3 :Ce scintillation crystal. The two photodetectors have high quantum efficiency and in particular 30% for R6231-01 and 42% for R7600-200 tube. The substantial difference is in the dynode structure, linear focused and metal channel for R6231 and R7600 respectively. In this work in order to verify the non-linearity effects on the pulse height distribution, due principally to the high and fast light production of LaBr 3 :Ce scintillator, we propose a 'peak by peak' procedure to calibrate the pulse height distribution. Utilizing a specific fragmentation of the calibration curve in subsets, the calculated energy values are very similar for both PMTs. This result confirmed the potentiality of the procedure to highlight the non-linearity effects on pulse height distribution.

Pulse height model for deuterated scintillation detectors

International Nuclear Information System (INIS)

Wang, Haitang; Enqvist, Andreas

2015-01-01

An analytical model of light pulse height distribution for finite deuterated scintillation detectors is created using the impulse approximation. Particularly, the energy distribution of a scattered neutron is calculated based on an existing collision probability scheme for general cylindrical shaped detectors considering double differential cross-sections. The light pulse height distribution is analytically and numerically calculated by convoluting collision sequences with the light output function for an EJ-315 detector from our measurements completed at Ohio University. The model provides a good description of collision histories capturing transferred neutron energy in deuterium-based scintillation materials. The resulting light pulse height distribution details pulse compositions and their corresponding contributions. It shows that probabilities of neutron collision with carbon and deuterium nuclei are comparable, however the light pulse amplitude due to collisions with carbon nuclei is small and mainly located at the lower region of the light pulse distribution axis. The model can explore those neutron interaction events that generate pulses near or below a threshold that would be imposed in measurements. A comparison is made between the light pulse height distributions given by the analytical model and measurements. It reveals a significant probability of a neutron generating a small light pulse due to collisions with carbon nuclei when compared to larger light pulse generated by collisions involving deuterium nuclei. This model is beneficial to understand responses of scintillation materials and pulse compositions, as well as nuclei information extraction from recorded pulses.

New-fashioned Multi-channel Analyzer Based on Bipartition Method

International Nuclear Information System (INIS)

Liu Mingjian; Zhang Yan; Yan Xuekun; Chen Ying

2009-01-01

A new-fashioned digital-analog converter (DAC) which can find the pulse-signal amplitude through dichotomy is devised. With this new DAC method, a 256-channel multi-channel pulse amplitude analyzer (MCA) is designed successfully, and its hardware and software are introduced in detail. This provides a new method for designing MCA. (authors)

High-speed nuclear quality pulse height analyzer for synchrotron-based applications

International Nuclear Information System (INIS)

Beche, Jean-Francois; Bucher, Jerome J.; Fabris, Lorenzo; Riot, Vincent J.

2001-01-01

A high throughput Pulse Height Analyzer system for synchrotron-based applications requiring high resolution, high processing speed and low dead time has been developed. The system is comprised of a 120ns 12-bit nuclear quality Analog to Digital converter with a self-adaptive fast peak detector-stretcher and a custom-made fast histogramming memory module that records and processes the digitized data. The histogramming module is packaged in a VME or VXI compatible interface. Data is transferred through a fast optical link from the memory interface to a computer. A dedicated data acquisition program matches the hardware characteristics of the histogramming memory module. The data acquisition system allows for two data collection modes: ''standard'' data acquisition mode where the data is accumulated and read in synchronization with an external trigger and ''live'' data acquisition mode where the system operates as a standard Pulse Height Analyzer. The acquisition, standard or live, can be performed on several channels simultaneously. A two-channel prototype has been demonstrated at the Stanford Synchrotron Radiation Laboratory accelerator in conjunction with an X-ray Fluorescence Absorption Spectroscopy experiment. A detailed description of the entire system is given and experimental data is shown

Development of a PDA Based Portable Pulse Height Analyzer System

International Nuclear Information System (INIS)

Mankheed, Panuphong; Ngernvijit, Narippawaj; Thong-Aram, Decho

2007-08-01

Full text: In this research a portable pulse height analyzer system was developed by application of a Personal Digital Assistant (PDAs) palm Tungsten T model together with Single Chip SCA developed by Department of Nuclear Technology, Chulalongkorn University to be used for education and research works. Capability of the developed system could measure both the energy and the average count rate of gamma rays. The results of this research showed that the gamma energy spectrum analysis of the developed system with a 2? x 2? NaI(Tl) detector could display photo peaks of Cs-137 and Co-60 at channel 57, channel 103, and channel 117 respectively. The energy resolution was found to be 7.14% at energy 661.66 keV of Cs-137

Super-pixel extraction based on multi-channel pulse coupled neural network

Science.gov (United States)

Xu, GuangZhu; Hu, Song; Zhang, Liu; Zhao, JingJing; Fu, YunXia; Lei, BangJun

2018-04-01

Super-pixel extraction techniques group pixels to form over-segmented image blocks according to the similarity among pixels. Compared with the traditional pixel-based methods, the image descripting method based on super-pixel has advantages of less calculation, being easy to perceive, and has been widely used in image processing and computer vision applications. Pulse coupled neural network (PCNN) is a biologically inspired model, which stems from the phenomenon of synchronous pulse release in the visual cortex of cats. Each PCNN neuron can correspond to a pixel of an input image, and the dynamic firing pattern of each neuron contains both the pixel feature information and its context spatial structural information. In this paper, a new color super-pixel extraction algorithm based on multi-channel pulse coupled neural network (MPCNN) was proposed. The algorithm adopted the block dividing idea of SLIC algorithm, and the image was divided into blocks with same size first. Then, for each image block, the adjacent pixels of each seed with similar color were classified as a group, named a super-pixel. At last, post-processing was adopted for those pixels or pixel blocks which had not been grouped. Experiments show that the proposed method can adjust the number of superpixel and segmentation precision by setting parameters, and has good potential for super-pixel extraction.

An Apple II -based bidimensional pulse height analyser

International Nuclear Information System (INIS)

Bateman, J.E.; Flesher, A.C.; Honeyman, R.N.; Pritchard, T.E.; Price, W.P.R.

1984-06-01

The implementation of a pulse height analyser function in an Apple II microcomputer using minimal purpose built hardware is described. Except for a small interface module the system consists of two suites of software, one giving a conventional one dimensional analysis on a span of 1024 channels, and the other a two dimensional analysis on a 128 x 128 image format. Using the recently introduced ACCELERATOR coprocessor card the system performs with a dead time per event of less than 50 μS. Full software facilities are provided for display, storage and processing of the data using standard Applesoft BASIC. (author)

FPGA based high-performance multi-channel analyzer with local histogram memory

International Nuclear Information System (INIS)

Kulkarni, C.P.; Vaidya, P.P.; Paulson, M.

2004-01-01

Modern nuclear spectroscopy systems demand for a Multi-Channel Analyzer (MCA) with higher resolution, faster speed and other advanced features. The MCA described here is targeted for such demanding applications. The MCA has an in-built local histogram memory and a memory management unit integrated in an FPGA (Field Programmable Gate Array) chip. In addition to the integrated low power digital circuitry, the system utilizes state of the art advanced analog circuits like low power, high speed and high precision comparators, op-amps, ADC and DAC. The operating resolution is selectable from 256 channels to 16384 channels for pulse height analysis. It supports high count rate applications (typically 100 KHz) without significant dead time penalty. It can have an USB bus interface with simple changes. In general, the MCA gives a high performance, compact and low power alternative for portable and battery operated systems as well as for high end laboratory instruments. (author)

First observation of multi-pulse X-ray train via multi-collision laser Compton scattering

International Nuclear Information System (INIS)

Kuroda, R.; Toyokawa, H.; Yasumoto, M.; Ikeura-Sekiguchi, H.; Koike, M.; Yamada, K.; Yanagida, T.; Nakajyo, T.; Sakai, F.

2009-01-01

A compact hard X-ray source via laser Compton scattering (LCS) has been developed for biological and medical applications at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan. The multi-collision LCS has been investigated in order to enhance the X-ray yields. The first observation of multi-pulse X-ray train with 6 pulses via the multi-collision LCS has been successfully demonstrated between the multi-bunch electron train with 6 bunches and the multi-pulse Ti:Sa laser train with 6 pulses. The 32 MeV electron train was generated from a Cs 2 Te photocathode rf gun with a multi-pulse UV laser and the S-band linac. The Ti:Sa laser train was obtained with the chirp pulse amplification (CPA) including the modified regenerative amplifier. The X-ray train with 6 pulses with 12.6 ns spacing was observed with the micro-channel plate (MCP). The maximum energy of the X-ray is analytically estimated to be about 24 keV and the total number of generated photons was calculated to be about 1.8x10 6 photons/train.

Determination of pseudo multi-pulse production rate in GM counters by correlation analysis between signal pulses

International Nuclear Information System (INIS)

Hashimoto, Kengo; Ueda, Taizou

1996-01-01

A technique, based on the correlation analysis of signal pulses in time sequence, is proposed to determine the production rate of the pseudo multi-pulse in Geiger-Mueller (GM) counter. With a multi-channel scaler initiated by a signal pulse, subsequent pulses are recorded in sequence. The production of the multi-pulse increases the counting probability immediately after the initiation. By examining the deviation of the measured probability from the ideal counting probability, the production rate and the average lag time to produce the multi-pulse can be determined. By the use of the present technique, the production rate and the average lag time were obtained for the various GM tubes. These results indicate that the consumption of the quench gas results in a significant increase in the production rate but little variation in the lag time, and that the lag time strongly depends on the tube diameter. (author)

Exploring the complementarity of THz pulse imaging and DCE-MRIs: Toward a unified multi-channel classification and a deep learning framework.

Science.gov (United States)

Yin, X-X; Zhang, Y; Cao, J; Wu, J-L; Hadjiloucas, S

2016-12-01

We provide a comprehensive account of recent advances in biomedical image analysis and classification from two complementary imaging modalities: terahertz (THz) pulse imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The work aims to highlight underlining commonalities in both data structures so that a common multi-channel data fusion framework can be developed. Signal pre-processing in both datasets is discussed briefly taking into consideration advances in multi-resolution analysis and model based fractional order calculus system identification. Developments in statistical signal processing using principal component and independent component analysis are also considered. These algorithms have been developed independently by the THz-pulse imaging and DCE-MRI communities, and there is scope to place them in a common multi-channel framework to provide better software standardization at the pre-processing de-noising stage. A comprehensive discussion of feature selection strategies is also provided and the importance of preserving textural information is highlighted. Feature extraction and classification methods taking into consideration recent advances in support vector machine (SVM) and extreme learning machine (ELM) classifiers and their complex extensions are presented. An outlook on Clifford algebra classifiers and deep learning techniques suitable to both types of datasets is also provided. The work points toward the direction of developing a new unified multi-channel signal processing framework for biomedical image analysis that will explore synergies from both sensing modalities for inferring disease proliferation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Pulse-height defect in single-crystal CVD diamond detectors

Energy Technology Data Exchange (ETDEWEB)

Beliuskina, O.; Imai, N. [The University of Tokyo, Center for Nuclear Study, Wako, Saitama (Japan); Strekalovsky, A.O.; Aleksandrov, A.A.; Aleksandrova, I.A.; Ilich, S.; Kamanin, D.V.; Knyazheva, G.N.; Kuznetsova, E.A.; Mishinsky, G.V.; Pyatkov, Yu.V.; Strekalovsky, O.V.; Zhuchko, V.E. [JINR, Flerov Laboratory of Nuclear Reactions, Dubna, Moscow Region (Russian Federation); Devaraja, H.M. [Manipal University, Manipal Centre for Natural Sciences, Manipal, Karnataka (India); Heinz, C. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Giessen (Germany); Heinz, S. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Giessen (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Hofmann, S.; Kis, M.; Kozhuharov, C.; Maurer, J.; Traeger, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Pomorski, M. [CEA, LIST, Diamond Sensor Laboratory, CEA/Saclay, Gif-sur-Yvette (France)

2017-02-15

The pulse-height versus deposited energy response of a single-crystal chemical vapor deposition (scCVD) diamond detector was measured for ions of Ti, Cu, Nb, Ag, Xe, Au, and of fission fragments of {sup 252} Cf at different energies. For the fission fragments, data were also measured at different electric field strengths of the detector. Heavy ions have a significant pulse-height defect in CVD diamond material, which increases with increasing energy of the ions. It also depends on the electrical field strength applied at the detector. The measured pulse-height defects were explained in the framework of recombination models. Calibration methods known from silicon detectors were modified and applied. A comparison with data for the pulse-height defect in silicon detectors was performed. (orig.)

Drift chamber and pulse height readout systems using analog multiplexing

International Nuclear Information System (INIS)

Cisneros, E.L; Kang, H.K.; Hall, J.N.; Larsen, R.S.

1976-11-01

Drift chamber and pulse-height readout systems are being developed for use in a new large scale detector at the SPEAR colliding beam facility. The systems are based upon 32 channels of sample-and-hold together with an analog multiplexer in a single-width CAMAC module. The modules within each crate are scanned by an autonomous controller containing a single ADC and memory plus arithmetic capability for offset, gain and linearity corrections. The drift chamber module has a facility for extracting hit wire information for use in trigger decision circuitry

Low-cost programmable pulse generator for particle telescope calibration

CERN Document Server

Sanchez, S; Seisdedos, M; Meziat, D; Carbajo, M; Medina, J; Bronchalo, E; Peral, L D; Rodríguez-Pacheco, J

1999-01-01

In this paper we present a new calibration system for particle telescopes including multipulse generator and digital controller. The calibration system generates synchronized pulses of variable height for every detector channel on the telescope. The control system is based on a commercial microcontroller linked to a personal computer through an RS-232 bidirectional line. The aim of the device is to perform laboratory calibration of multi-detector telescopes prior to calibration at accelerator. This task includes evaluation of linearity and resolution of each detector channel, as well as coincidence logic. The heights of the pulses sent to the detectors are obtained by Monte Carlo simulation of telescope response to a particle flux of any desired geometry and composition.

FERDO/FERD, Unfolding of Pulse-Height Spectrometer Spectra

International Nuclear Information System (INIS)

Rust, B.W.; Ingersoll, D.T.; Burrus, W.R.

1985-01-01

1 - Description of problem or function: FERDO and FERD are unfolding codes which can be used to correct observed pulse-height distributions for the non-ideal response of a pulse-height spectrometer or to solve poorly conditioned linear equations. 2 - Method of solution: It is assumed that the response of the spectrometer is given by Ax = b, where A is the spectrometer response function matrix, x is the unknown spectrum, and b is the pulse-height distribution. FERDO does not resolve directly for x but instead solves for p = Wx, where W is a 'window function matrix'. Typically, W is the resolution function of an ideal spectrometer which has a single Gaussian response. The effective resolution of the unfolding solution may be varied by the choice of W. Confidence intervals are found for each element of the solution p

Estimate of pulse-sequence data acquisition system for multi-dimensional measurement

Energy Technology Data Exchange (ETDEWEB)

Kitamura, Yasunori; Sakae, Takeji; Nohtomi, Akihiro; Matoba, Masaru [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering; Matsumoto, Yuzuru

1996-07-01

A pulse-sequence data acquisition system has been newly designed and estimated for the measurement of one- or multi-dimensional pulse train coming from radiation detectors. In this system, in order to realize the pulse-sequence data acquisition, the arrival time of each pulse is recorded to a memory of a personal computer (PC). For the multi-dimensional data acquisition with several input channels, each arrival-time data is tagged with a `flag` which indicates the input channel of arriving pulse. Counting losses due to the existence of processing time of the PC are expected to be reduced by using a First-In-First-Out (FIFO) memory unit. In order to verify this system, a computer simulation was performed, Various sets of random pulse trains with different mean pulse rate (1-600 kcps) were generated by using Monte Carlo simulation technique. Those pulse trains were dealt with another code which simulates the newly-designed data acquisition system including a FIFO memory unit; the memory size was assumed to be 0-100 words. And the recorded pulse trains on the PC with the various FIFO memory sizes have been observed. From the result of the simulation, it appears that the system with 3 words FIFO memory unit works successfully up to the pulse rate of 10 kcps without any severe counting losses. (author)

Estimate of pulse-sequence data acquisition system for multi-dimensional measurement

International Nuclear Information System (INIS)

Kitamura, Yasunori; Sakae, Takeji; Nohtomi, Akihiro; Matoba, Masaru; Matsumoto, Yuzuru.

1996-01-01

A pulse-sequence data acquisition system has been newly designed and estimated for the measurement of one- or multi-dimensional pulse train coming from radiation detectors. In this system, in order to realize the pulse-sequence data acquisition, the arrival time of each pulse is recorded to a memory of a personal computer (PC). For the multi-dimensional data acquisition with several input channels, each arrival-time data is tagged with a 'flag' which indicates the input channel of arriving pulse. Counting losses due to the existence of processing time of the PC are expected to be reduced by using a First-In-First-Out (FIFO) memory unit. In order to verify this system, a computer simulation was performed, Various sets of random pulse trains with different mean pulse rate (1-600 kcps) were generated by using Monte Carlo simulation technique. Those pulse trains were dealt with another code which simulates the newly-designed data acquisition system including a FIFO memory unit; the memory size was assumed to be 0-100 words. And the recorded pulse trains on the PC with the various FIFO memory sizes have been observed. From the result of the simulation, it appears that the system with 3 words FIFO memory unit works successfully up to the pulse rate of 10 kcps without any severe counting losses. (author)

A 12-bit spectroscopy analog-to-digital converter type SAA (Successive Approximation type with channel width Averaging) intended for multichannel pulse height analyzer SWAN-1 based on IBM PC/XT/AT

International Nuclear Information System (INIS)

Borsuk, S.; Kulka, Z.

1989-12-01

A 12-bit spectroscopy analog-to-digital converter (ADC) type SAA (Successive Approximation type with channel width Averaging) intended for multichannel pulse height analyzer SWAN-1 based on IBM PC/XT/AT has been described. Design principles, specifications and measurements of a fundamental SAA-2 converter version are reported. Finally, two next versions of the converter with introduced modifications are discussed. 6 refs., 7 figs. (author)

Realization of an optical multi and mono-channel analyzer, associated to a streak camera. Application to metrology of picosecond low intensity luminous pulses

International Nuclear Information System (INIS)

Roth, J.M.

1985-02-01

An electronic system including a low light level television tube (Nocticon) to digitize images from streak cameras is studied and realized. Performances (sensibility, signal-to-noise ratio) are studied and compared with a multi-channel analyzer using a linear network of photodiodes. It is applied to duration and amplitude measurement of short luminous pulses [fr

High-energy few-cycle pulse compression through self-channeling in gases

International Nuclear Information System (INIS)

Hauri, C.; Merano, M.; Trisorio, A.; Canova, F.; Canova, L.; Lopez-Martens, R.; Ruchon, T.; Engquist, A.; Varju, K.; Gustafsson, E.

2006-01-01

successfully scaled this pulse compression regime to the multi-mJ level. In this case, temporally clean 10-fs pulses with energies up to 1.8 mJ could be generated through self-channeling of 3.5 mJ, 40-fs pulses. Again, the spectrally broadened pulses are seen to carry large negative chirps and the shortest measured pulse duration of 9.5-fs was achieved by inserting more than 1 cm of glass in order to compensate for the negative GDD. Single-shot measurements show the exceptional shot-to-shot stability of this pulse compression scheme. In conclusion, we demonstrate a stable nonlinear pulse compression technique based on self-channeling of intense 40-fs pulses in gases, in which ultrashort pulses are efficiently generated with unexpected large negative chirp. The strongly pre-compensated spectral phase characteristics of such few-cycle pulses makes them a practical driving source for further high-field applications since the shortest pulse durations can be achieved on target by simple propagation through bulk material (e.g. vacuum window). Simulations involving the solution to the nonlinear propagation equation are underway in order to understand this unexpected pulse compression regime and to find optimal conditions for further scaling in energy.

Evaluation of the potential of soil remediation by direct multi-channel pulsed corona discharge in soil.

Science.gov (United States)

Wang, Tie Cheng; Qu, Guangzhou; Li, Jie; Liang, Dongli

2014-01-15

A novel approach, named multi-channel pulsed corona discharge in soil, was developed for remediating organic pollutants contaminated soil, with p-nitrophenol (PNP) as the model pollutant. The feasibility of PNP degradation in soil was explored by evaluating effects of pulse discharge voltage, air flow rate and soil moisture on PNP degradation. Based on roles of chemically active species and evolution of degradation intermediates, PNP degradation processes were discussed. Experimental results showed that about 89.4% of PNP was smoothly degraded within 60min of discharge treatment at pulse discharge voltage 27kV, soil moisture 5% and air flow rate 0.8Lmin(-1), and the degradation process fitted the first-order kinetic model. Increasing pulse discharge voltage was found to be favorable for PNP degradation, but not for energy yield. There existed appropriate air flow rate and soil moisture for obtaining gratifying PNP degradation efficacy. Roles of radical scavenger and measurement of active species suggested that ozone, H2O2, and OH radicals played very important roles in PNP degradation. CN bond in PNP molecule was cleaved, and the main intermediate products such as hydroquinone, benzoquinone, catechol, phenol, acetic acid, formic acid, oxalic acid, NO2(-) and NO3(-) were identified. Possible pathway of PNP degradation in soil in such a system was proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Multi-channel imaging cytometry with a single detector

Science.gov (United States)

Locknar, Sarah; Barton, John; Entwistle, Mark; Carver, Gary; Johnson, Robert

2018-02-01

Multi-channel microscopy and multi-channel flow cytometry generate high bit data streams. Multiple channels (both spectral and spatial) are important in diagnosing diseased tissue and identifying individual cells. Omega Optical has developed techniques for mapping multiple channels into the time domain for detection by a single high gain, high bandwidth detector. This approach is based on pulsed laser excitation and a serial array of optical fibers coated with spectral reflectors such that up to 15 wavelength bins are sequentially detected by a single-element detector within 2.5 μs. Our multichannel microscopy system uses firmware running on dedicated DSP and FPGA chips to synchronize the laser, scanning mirrors, and sampling clock. The signals are digitized by an NI board into 14 bits at 60MHz - allowing for 232 by 174 pixel fields in up to 15 channels with 10x over sampling. Our multi-channel imaging cytometry design adds channels for forward scattering and back scattering to the fluorescence spectral channels. All channels are detected within the 2.5 μs - which is compatible with fast cytometry. Going forward, we plan to digitize at 16 bits with an A-toD chip attached to a custom board. Processing these digital signals in custom firmware would allow an on-board graphics processing unit to display imaging flow cytometry data over configurable scanning line lengths. The scatter channels can be used to trigger data buffering when a cell is present in the beam. This approach enables a low cost mechanically robust imaging cytometer.

Comparison of performance of analog-to-digital converters (ADC) for pulse height analyzers

International Nuclear Information System (INIS)

Suzuki, Shogo; Hirai, Shoji

1981-01-01

In the recent ADCs for pulse height analyzers (PHA), Wilkinson type is a leading one, and those with 50 to 200 MHz clock frequency and 8K channel are mostly on the market. The comparison of the performance of ADCs was conducted under the condition of using these multi-channel PHAs as γ-ray spectrometers. The following three ADCs were compared: ADC incorporated in CANBERRA 8100 MCA, and CANBERRA 8060 ADCs used as the ADCs for 1st and 2nd GAMA systems. In this case, the conversion gains of these ADCs were set at 4K because the memory of 8100 MCA was 4K, and the GAMA systems were also mostly operated at 4K. In this paper, report is made on the measurements of dead time, the change of γ peaks immediately after the power was turned on, the temperature dependence of ADCs the long term stability of ADCs, derivative non-linearity, and integration non-linearity. The dead time of the ADC of 8100 CMA was shorter in the range up to 1000 channels. The temperature dependence was -0.017%/deg C in 8100 MCA, and -0.061 and -0.072%/deg C in GAMA. The long term stability was -0.02%/14 hr in 8100 MCA, and -0.027%/14 hr in 8060 of 1st GAMA. The derivative non-linearity was 0.45% in 8100 MCA, 0.67% in 8060 of 1st GAMA, and the integration non-linearity was 0.075% for 8100 MCA, and 0.085 - 0.1% in 8060 ADCs. Also, the change of γ peaks immediately after the power was turned on for 8100 ADC was better than that of 8060 ADC. (Wakatsuki, Y.)

Twenty-channel high-voltage pulse generators

International Nuclear Information System (INIS)

Anan'in, P.S.; Kashirin, A.P.

1980-01-01

A 20-channel high-voltage pulse generator operating with a mismatched load is described. The generator contains shaping lines 20 m long made of coaxial cable, a trigatron-type discharged, and isolating plates. The channel characteristic impedance is 50 Ohm. The maximum pulse amplitude is up to 15 kV on a high-resistance load and 7.5 kV on a matched one. The pulse duration is 100 ns at a pulse rise time of 12 ns, the delay introduced by the generator is 200 +-2.5 ns. Provision is made in the control circuit for compensation of the shaped pulse and separation of a pulse reflected from the load. The reflected pulse shape and amplitude characterize load parameters. Generator tests proved its high operational reliability (after 10 5 operations no significant changes in generator performances have been observed). The generator is intended for filmless data output from spark chambers

Multi-channel time-division integrator in HL-2A

International Nuclear Information System (INIS)

Yan Ji

2008-01-01

HL-2A is China's first Tokamak device with divertor configuration (magnetic confinement controlled nuclear fusion device). To find out the details of on-going fusion reaction at different times is of important significance in achieving controlled nuclear fusion. We developed a new type multi-channel time-division integrator for HL-2A. It has functions of automatic cutting off negative pulse of the input signals, optional integrating time division spacing 0.2-1 ms, TTL starting trigger signal, automatic regularly work 20 s, and integrating 10 channel at the same time. (authors)

Multi-channel integrated circuits for the detection and measurement of ionizing radiation

International Nuclear Information System (INIS)

Engel, G.L.; Duggireddi, N.; Vangapally, V.; Elson, J.M.; Sobotka, L.G.; Charity, R.J.

2011-01-01

The Integrated Circuits (IC) Design Research Laboratory at Southern Illinois University Edwardsville (SIUE) has collaborated with the Nuclear Reactions Group at Washington University (WU) to develop a family of multi-channel integrated circuits. To date, the collaboration has successfully produced two micro-chips. The first was an analog shaped and peak sensing chip with on-board constant-fraction discriminators and sparsified readout. This chip is known as Heavy-Ion Nuclear Physics-16 Channel (HINP16C). The second chip, christened PSD8C, was designed to logically complement (in terms of detector types) the HINP16C chip. Pulse Shape Discrimination-8 Channel (PSD8C), featuring three settable charge integration windows per channel, performs pulse shape discrimination (PSD). This paper summarizes the design, capabilities, and features of the HINP16C and PSD8C ICs. It proceeds to discuss the modifications, made to the ICs and their associated systems, which have attempted to improve ease of use, increase performance, and extend capabilities. The paper concludes with a brief discussion of what may be the next chip (employing a multi-sampling scheme) to be added to our CMOS ASIC 'tool box' for radiation detection instrumentation.

Research on development of multi-channel analyzer used for monitoring and warning radiation equipment

International Nuclear Information System (INIS)

Nguyen Van Sy; Dang Quang Thieu; Nguyen Thi Bao My

2015-01-01

The subject assigned to this paper presents research on development of multi-channel analyzer used for monitoring and warning environmental radiation equipment under the project KC.05.16/11-15 Research on manufacturing equipment monitoring and warning radiation. In this thematic we have two subjects that need to be resolved such as: i) Designing spectroscopy amplifier block (AMP) duty pulse signals obtained about few hundred millivolts output from scintillation detector preamplifier, amplified as a few volts and the standard Gaussian pulses shaped to connect to the analog-to-digital converter. The spectroscopy amplifier block can change the gain by digital control to respond to the problem of automatic spectrum stability for multi-channel analyzer systems. ii) Designing analog-to-digital converter block (ADC) in accordance with the actual conditions, such as high stability, fast conversion time, high throughput, and it consumes low energy. Selecting suitable microprocessor for fast connection ability, to operate reliably paired with the analog-to-digital converter into a multi-channel analyzer (MCA) serving analysis. (author)

Modeling Photo-multiplier Gain and Regenerating Pulse Height Data for Application Development

Science.gov (United States)

Aspinall, Michael D.; Jones, Ashley R.

2018-01-01

Systems that adopt organic scintillation detector arrays often require a calibration process prior to the intended measurement campaign to correct for significant performance variances between detectors within the array. These differences exist because of low tolerances associated with photo-multiplier tube technology and environmental influences. Differences in detector response can be corrected for by adjusting the supplied photo-multiplier tube voltage to control its gain and the effect that this has on the pulse height spectra from a gamma-only calibration source with a defined photo-peak. Automated methods that analyze these spectra and adjust the photo-multiplier tube bias accordingly are emerging for hardware that integrate acquisition electronics and high voltage control. However, development of such algorithms require access to the hardware, multiple detectors and calibration source for prolonged periods, all with associated constraints and risks. In this work, we report on a software function and related models developed to rescale and regenerate pulse height data acquired from a single scintillation detector. Such a function could be used to generate significant and varied pulse height data that can be used to integration-test algorithms that are capable of automatically response matching multiple detectors using pulse height spectra analysis. Furthermore, a function of this sort removes the dependence on multiple detectors, digital analyzers and calibration source. Results show a good match between the real and regenerated pulse height data. The function has also been used successfully to develop auto-calibration algorithms.

The use of logarithmic pulse height and energy scales in organic scintillator spectroscopy

International Nuclear Information System (INIS)

Whittlestone, S.

1980-01-01

The use of logarithmic pulse height and energy scales is advantageous for organic for organic scintillator neutron spectroscopy, providing an expanded dynamic range and economy of computer usage. An experimental logarithmic pulse height analysis system is shown to be feasible. A pulse height spectrum from a neutron measurement has been analysed using linear and logarithmic scales; the latter reduced the computer storage requirements by a factor of 13 and analysis time by 8.7, and there was no degradation of the analysed spectrum. Most of the arguments favouring use of logarithmic scales apply equally well to other types of scintillation spectroscopy. (orig.)

Optimal Linear Filters for Pulse Height Measurements in the Presence of Noise

International Nuclear Information System (INIS)

Nygaard, K.

1966-07-01

For measurements of nuclear pulse height spectra a linear filter is used between the pulse amplifier and the pulse height recorder so as to improve the signal/noise ratio. The problem of finding the optimal filter is investigated with emphasis on technical realizability. The maximum available signal/noise ratio is theoretically calculated on the basis of all the information which can be found in the output of the pulse amplifier, and on an assumed a priori knowledge of the pulse time of arrival. It is then shown that the maximum available signal/noise ratio can be obtained with practical measurements without any a priori knowledge of pulse time of arrival, and a general description of the optimal linear filter is given. The solution is unique, technically realizable, and based solely on data (noise power spectrum and pulse shape) which can be measured at the output terminals of the pulse amplifier used

Optimal Linear Filters for Pulse Height Measurements in the Presence of Noise

Energy Technology Data Exchange (ETDEWEB)

Nygaard, K

1966-07-15

For measurements of nuclear pulse height spectra a linear filter is used between the pulse amplifier and the pulse height recorder so as to improve the signal/noise ratio. The problem of finding the optimal filter is investigated with emphasis on technical realizability. The maximum available signal/noise ratio is theoretically calculated on the basis of all the information which can be found in the output of the pulse amplifier, and on an assumed a priori knowledge of the pulse time of arrival. It is then shown that the maximum available signal/noise ratio can be obtained with practical measurements without any a priori knowledge of pulse time of arrival, and a general description of the optimal linear filter is given. The solution is unique, technically realizable, and based solely on data (noise power spectrum and pulse shape) which can be measured at the output terminals of the pulse amplifier used.

A multi-channel integrated circuit for use in low- and intermediate-energy nuclear physics-HINP16C

Energy Technology Data Exchange (ETDEWEB)

Engel, George L. [Department of Electrical and Computer Engineering, VLSI Design Research Laboratory, Southern Illinois University Edwardsville, Engineering Building, Room 3047, Edwardsville, IL 62026-1801 (United States)]. E-mail: gengel@siue.edu; Sadasivam, Muthukumar [Department of Electrical and Computer Engineering, VLSI Design Research Laboratory, Southern Illinois University Edwardsville, Engineering Building, Room 3047, Edwardsville, IL 62026-1801 (United States); Nethi, Mythreyi [Department of Electrical and Computer Engineering, VLSI Design Research Laboratory, Southern Illinois University Edwardsville, Engineering Building, Room 3047, Edwardsville, IL 62026-1801 (United States); Elson, Jon M. [Department of Chemistry, Washington University, Saint Louis, MO, 63130 (United States); Sobotka, Lee G. [Department of Chemistry, Washington University, Saint Louis, MO, 63130 (United States); Charity, Robert J. [Department of Chemistry, Washington University, Saint Louis, MO, 63130 (United States)

2007-04-11

The design, simulations, and tests of a 16-channel chip for solid-state detectors are presented. The chip produces sparsified pulse trains for both linear (pulse height) and timing (relative to an external reference) and allows the use of one of two internal charge sensitive amplifiers or an external amplifier. A shaper and peak detector are implemented in the linear branch and a pseudo-constant fraction discriminator and time-to-voltage converter are implemented in the logic/timing branch. The internal plus external gain options and the preparation of both pulse height and timing pulse trains suitable for pipeline ADCs, makes the chip suitable for a wide variety of applications. The chip was fabricated in the AMI 0.5 {mu}m n-well (C5N) process available through MOS implementation services (MOSIS)

4-channel time delayed pulse generator

International Nuclear Information System (INIS)

Wetzel, L.F.S.; Rossi, J.O.; Del Bosco, E.

1987-02-01

It is described the project of a 4-channel delayed pulse generator employed to trigger the plasma centrifuge experiment of the Laboratorio Associado de Plasmas. The circuit delivers pulses with amplitude of 15V, full width at half maximum of 50μs and rise time of 0.7μs. The maximum time delay is 100ms. There are two channels with a fine adjustment of 0-1ms. The system can be manually or automatically driven. (author) [pt

Multi-DSP and FPGA based Multi-channel Direct IF/RF Digital receiver for atmospheric radar

Science.gov (United States)

Yasodha, Polisetti; Jayaraman, Achuthan; Kamaraj, Pandian; Durga rao, Meka; Thriveni, A.

2016-07-01

to DDC block, which down converts the data to base-band. The DDC block has NCO, mixer and two chains of Bessel filters (fifth order cascaded integration comb filter, two FIR filters, two half band filters and programmable FIR filters) for in-phase (I) and Quadrature phase (Q) channels. The NCO has 32 bits and is set to match the output frequency of ADC. Further, DDC down samples (decimation) the data and reduces the data rate to 16 MSPS. This data is further decimated and the data rate is reduced down to 4/2/1/0.5/0.25/0.125/0.0625 MSPS for baud lengths 0.25/0.5/1/2/4/8/16 μs respectively. The down sampled data is then fed to decoding block, which performs cross correlation to achieve pulse compression of the binary-phase coded data to obtain better range resolution with maximum possible height coverage. This step improves the signal power by a factor equal to the length of the code. Coherent integration block integrates the decoded data coherently for successive pulses, which improves the signal to noise ratio and reduces the data volume. DDC, decoding and coherent integration blocks are implemented in Xilinx vertex5 FPGA. Till this point, function of all six channels is same for DBS mode and multi-receiver modes. Data from vertex5 FPGA is transferred to PC via GbE-1 interface for multi-modes or to two Analog devices make ADSP-TS201 DSP chips (A and B), via link port for DBS mode. ADSP-TS201 chips perform the normalization, DC removal, windowing, FFT computation and spectral averaging on the data, which is transferred to storage/display PC via GbE-2 interface for real-time data display and data storing. Physical layer of GbE interface is implemented in an external chip (Marvel 88E1111) and MAC layer is implemented internal to vertex5 FPGA. The MCDRx has total 4 GB of DDR2 memory for data storage. Spartan6 FPGA is used for generating timing signals, required for basic operation of the radar and testing of the MCDRx.

Output pulse height distribution of the GM counters

International Nuclear Information System (INIS)

Zhang Songshou; Xiong Jianping

1995-01-01

The GM counters are the radiation detectors most in use. It has special advantages compared with other detectors. This paper introduces the output pulse height distribution of the GM counters, gives the measuring instruments and methods. The measuring results, some discussions, and useful conclusion are given as well

Laboratory tests of the Pulse Height Analysis system for Wendelstein 7-X

Science.gov (United States)

Kubkowska, M.; Czarnecka, A.; Figacz, W.; Jabłoński, S.; Kaczmarczyk, J.; Krawczyk, N.; Ryć, L.; Biedermann, C.; Koenig, R.; Thomsen, H.; Weller, A.; W7-X Team

2015-10-01

A pulse height analysis (PHA) system has been designed and manufactured for the Wendelstein 7-X stellarator, in such a way as to be already compatible with later quasi-continuous operation requirements. The diagnostic will provide X-ray spectra with energy resolution better than 180 eV . The system has three energy channels: 0.25-20 keV, 0.95-20 keV and 1.5-20 keV . For each channel a separate Silicon Drift Detector (SDD) equipped with a suitably selected beryllium foil is used. The range of the 3 energy channels can be further adapted to particular experiments by moving via a pneumatic actuator additional beryllium filters in front of the fixed ones. The PHA system is intended for measuring impurity species (e.g. C, Fe, Ni), electron temperature and for investigating possible suprathermal tails in the spectra. The system will be installed on the horizontal port AEK50 on W7-X. The SDD detectors, the replaceable filters and the adjustable piezo driven slits which allow to suitably adapt the X-ray signal intensity are mounted inside a vacuum chamber which is connected to the plasma vessel via a gate valve. The on-air diagnostic components are the preamplifiers, the Digital X-Ray Processor (XIA, U.S.A.), a computer, and an X-ray calibration source. For controlling the operation of the entire diagnostic system, as well as, for the data acquisition of the electrical pulses coming a special code was developed. The paper presents the construction of the PHA system for W7-X and the laboratory tests of its mechanical parts together with the information on the code developed to operate the diagnostic. The diagnostic was also tested and characterised by measuring Fe55 spectrum and fluorescence spectra of Ni, Fe, Cr and Cu induced by an X-ray mini-tube.

Cadmium-Zinc-Telluride photon detector for epithermal neutron spectroscopy--pulse height response characterisation

International Nuclear Information System (INIS)

Tardocchi, M.; Pietropaolo, A.; Andreani, C.; Bracco, A.; D'Angelo, A.; Gorini, G.; Imberti, S.; Senesi, R.; Rhodes, N.J.; Schooneveld, E.M.

2004-01-01

The Resonance Detector Spectrometer was recently revised for neutron spectroscopic studies in the eV energy region. In this technique one makes use of a photon detector to record the gamma emission from analyser foils used as neutron-gamma converters. The pulse-height response of a Cadmium-Zinc-Telluride photon detector to neutron capture emission from 238 U and 197 Au analyser foils was characterised in the neutron energy range 1-200 eV. The experiment was performed on the VESUVIO spectrometer at the ISIS neutron-pulsed source. A biparametric data acquisition, specifically developed for these measurements, allowed the simultaneous measurements of both the neutron time of flight and γ pulse-height spectra. Through the analysis of the γ pulse-height spectra the main components of the signal associated with resonant and non-resonant neutron absorption were identified. It was also shown that, in principle, energy discrimination can be used to improve the signal to background ratio of the neutron time-of-flight measurement

Multi-Channel Amplifier-Discriminator for Highly Time-Resolved Detection

CERN Document Server

Despeisse, M; Lapington, J; Jarron, P

2011-01-01

A low-power multi-channel amplifier-discriminator was developed for application in highly time-resolved detection systems. The proposed circuit architecture, so-called Nino, is based on a time-over-threshold approach and shows a high potential for time-resolved readout of solid-state photo-detectors and of detectors based on vacuum technologies. The Irpics circuit was designed in a 250 nm CMOS technology, implementing 32 channels of a Nino version optimized to achieve high-time resolution on the output low-voltage differential signals (LVDS) while keeping a low power consumption of 10 mW per channel. Electrical characterizations of the circuit demonstrate a very low intrinsic time jitter on the output pulse leading edge, measured below 10 ps rms for each channel for high input signal charges (100 fC) and below 25 ps rms for low input signal charges (20-100 fC). The read-out architecture moreover permits to retrieve the input signal charge from the timing measurements, while a calibration procedure was develop...

Measurement of H'(0.07) with pulse height weighting integration method

International Nuclear Information System (INIS)

Liye, LIU; Gang, JIN; Jizeng, MA

2002-01-01

H'(0.07) is an important quantity for radiation field measurement in health physics. One of the plastic scintillator measurement methods is employing the weak current produced by PMT. However, there are some weaknesses in the current method. For instance: sensitive to environment humidity and temperature, non-linearity energy response. In order to increase the precision of H'(0.07) measurement, a Pulse Height Weighting Integration Method is introduced for its advantages: low noise, high sensitivity, data processable, wide measurement range. Pulse Height Weighting Integration Method seems to be acceptable to measure directional dose equivalent. The representative theoretical energy response of the pre-described method accords with the preliminary experiment result

Multi-channel polarized thermal emitter

Science.gov (United States)

Lee, Jae-Hwang; Ho, Kai-Ming; Constant, Kristen P

2013-07-16

A multi-channel polarized thermal emitter (PTE) is presented. The multi-channel PTE can emit polarized thermal radiation without using a polarizer at normal emergence. The multi-channel PTE consists of two layers of metallic gratings on a monolithic and homogeneous metallic plate. It can be fabricated by a low-cost soft lithography technique called two-polymer microtransfer molding. The spectral positions of the mid-infrared (MIR) radiation peaks can be tuned by changing the periodicity of the gratings and the spectral separation between peaks are tuned by changing the mutual angle between the orientations of the two gratings.

Conversion of ADC pulse heights into MIP units (NUMASS test data, September 1991)

International Nuclear Information System (INIS)

Zhang, Q.P.

1993-04-01

ADC calibration is an important part of the data analysis in particle physics. Data analysis of ADC pulse heights is based on a physical unit which is called MIP (most probable energy loss of Minimum Ionization Particles). This paper describes the ADC calibration work for the September 1991 NUMASS test data, which were produced at CERN at the SPS facility. The Vavilov function is used to fit the energy loss distributions of minimum ionizing particles traversing the time of flight scintillators embedded in the uranium scintillator calorimeter. It is assumed that the energy loss distribution is the same for identical scintillators and the value at the peak of these distributions is used, i.e., the most probable energy loss, as a physical unit to derive the gains of the individual readout channels

Performances of Hybrid Amplitude Shape Modulation for UWB Communications Systems over AWGN Channel in a Single and Multi-User Environment

Directory of Open Access Journals (Sweden)

M. Herceg

2009-09-01

Full Text Available This paper analyzes the performance of the hybrid Amplitude Shape Modulation (h-ASM scheme for the time-hopping ultra-wideband (TH-UWB communication systems in the single and multi-user environment. h-ASM is the combination of Pulse Amplitude Modulation (PAM and Pulse Shape Modulation (PSM based on modified Hermite pulses (MHP. This scheme is suitable for high rate data transmission applications because b = log2(MN bits can be mapped with one waveform. The channel capacity and error probability over AWGN channel are derived and compared with other modulation schemes.

A high-throughput, multi-channel photon-counting detector with picosecond timing

Science.gov (United States)

Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

2009-06-01

High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

A high-throughput, multi-channel photon-counting detector with picosecond timing

International Nuclear Information System (INIS)

Lapington, J.S.; Fraser, G.W.; Miller, G.M.; Ashton, T.J.R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

2009-01-01

High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

Controlling Plasma Channels through Ultrashort Laser Pulse Filamentation

Science.gov (United States)

Ionin, Andrey; Seleznev, Leonid; Sunchugasheva, Elena

2013-09-01

A review of studies fulfilled at the Lebedev Institute in collaboration with the Moscow State University and Institute of Atmospheric Optics in Tomsk on influence of various characteristics of ultrashort laser pulse on plasma channels formed under its filamentation is presented. Filamentation of high-power laser pulses with wavefront controlled by a deformable mirror, with cross-sections spatially formed by various diaphragms and with different wavelengths was experimentally and numerically studied. An application of plasma channels formed due to filamentation of ultrashort laser pulse including a train of such pulses for triggering and guiding long electric discharges is discussed. The research was supported by RFBR Grants 11-02-12061-ofi-m and 11-02-01100, and EOARD Grant 097007 through ISTC Project 4073 P

Flow field optimization for proton exchange membrane fuel cells with varying channel heights and widths

International Nuclear Information System (INIS)

Wang Xiaodong; Huang Yuxian; Cheng, C.-H.; Jang, J.-Y.; Lee, D.-J.; Yan, W.-M.; Su Ay

2009-01-01

The optimal cathode flow field design of a single serpentine proton exchange membrane fuel cell is obtained by adopting a combined optimization procedure including a simplified conjugate-gradient method (SCGM) and a completely three-dimensional, two-phase, non-isothermal fuel cell model. The cell output power density P cell is the objective function to be maximized with channel heights, H 1 -H 5 , and channel widths, W 2 -W 5 as search variables. The optimal design has tapered channels 1, 3 and 4, and diverging channels 2 and 5, producing 22.51% increment compared with the basic design with all heights and widths setting as 1 mm. Reduced channel heights of channels 2-4 significantly enhance sub-rib convection to effectively transport oxygen to and liquid water out of diffusion layer. The final diverging channel prevents significant leakage of fuel to outlet via sub-rib convection from channel 4. Near-optimal design without huge loss in cell performance but is easily manufactured is discussed.

Dense Clustered Multi-Channel Wireless Sensor Cloud

Directory of Open Access Journals (Sweden)

Sivaramakrishnan Sivakumar

2015-08-01

Full Text Available Dense Wireless Sensor Network Clouds have an inherent issue of latency and packet drops with regards to data collection. Though there is extensive literature that tries to address these issues through either scheduling, channel contention or a combination of the two, the problem still largely exists. In this paper, a Clustered Multi-Channel Scheduling Protocol (CMSP is designed that creates a Voronoi partition of a dense network. Each partition is assigned a channel, and a scheduling scheme is adopted to collect data within the Voronoi partitions. This scheme collects data from the partitions concurrently and then passes it to the base station. CMSP is compared using simulation with other multi-channel protocols like Tree-based Multi-Channel, Multi-Channel MAC and Multi-frequency Media Access Control for wireless sensor networks. Results indicate CMSP has higher throughput and data delivery ratio at a lower power consumption due to network partitioning and hierarchical scheduling that minimizes load on the network.

Design of multi-channel amplitude analyzer base on LonWorks

International Nuclear Information System (INIS)

Zhang Ying; Zhao Lihong; Chen Aihua

2008-01-01

The paper introduces the multi-channel analyzer which adopts LonWorks technology. The system detects the pulse peak by hardware circuits and controls data acquisition and network communication by Micro Controller and Unit and Neuron chip. SCM is programmed by Keil C51; the communication between SCM and nerve cell is realized by Neron C language, and the computer program is written by VB language. Test results show that this analyzer is with fast conversion speed and low power consumption. (authors)

Pulse height measurements and electron attachment in drift chambers operated with Xe,CO2 mixtures

CERN Document Server

Andronic, A

2003-01-01

We present pulse height measurements in drift chambers operated with Xe,CO2 gas mixtures. We investigate the attachment of primary electrons on oxygen and SF6 contaminants in the detection gas. The measurements are compared with simulations of properties of drifting electrons. We present two methods to check the gas quality: gas chromatography and Fe55 pulse height measurements using monitor detectors.

Pulse height measurements and electron attachment in drift chambers operated with Xe,CO2 mixtures

International Nuclear Information System (INIS)

Andronic, A.; Appelshaeuser, H.; Blume, C.; Braun-Munzinger, P.; Bucher, D.; Busch, O.; Ramirez, A.C.A. Castillo; Catanescu, V.; Ciobanu, M.; Daues, H.; Devismes, A.; Emschermann, D.; Fateev, O.; Garabatos, C.; Herrmann, N.; Ivanov, M.; Mahmoud, T.; Peitzmann, T.; Petracek, V.; Petrovici, M.; Reygers, K.; Sann, H.; Santo, R.; Schicker, R.; Sedykh, S.; Shimansky, S.; Simon, R.S.; Smykov, L.; Soltveit, H.K.; Stachel, J.; Stelzer, H.; Tsiledakis, G.; Vulpescu, B.; Wessels, J.P.; Windelband, B.; Winkelmann, O.; Xu, C.; Zaudtke, O.; Zanevsky, Yu.; Yurevich, V.

2003-01-01

We present pulse height measurements in drift chambers operated with Xe,CO 2 gas mixtures. We investigate the attachment of primary electrons on oxygen and SF 6 contaminants in the detection gas. The measurements are compared with simulations of properties of drifting electrons. We present two methods to check the gas quality: gas chromatography and 55 Fe pulse height measurements using monitor detectors

Multi-channel Kondo necklace

International Nuclear Information System (INIS)

Fazekas, P.; Kee Haeyoung.

1993-06-01

A multi-channel generalization of Doniach's Kondo necklace model is formulated, and its phase diagram studied in the mean-field approximation. Our intention is to introduce the possible simplest model which displays some of the features expected from the overscreened Kondo lattice. The N conduction electron channels are represented by N sets of pseudospins τ J , j = 1 1,..., N which are all antiferromagnetically coupled to a periodic array of modul S = 1/2 spins. Exploiting permutation symmetry in the channel index j allows us to write down the self-consistency equation for general N. For N > 2, we find that the critical temperature is rising with increasing Kondo interaction; we interpret this effect by pointing out that the Kondo coupling creates the composite pseudospin objects which undergo an ordering transition. The relevance of our findings to the underlying fermionic multi-channel problem is discussed. (author). 33 refs, 1 fig

Modelling customer behaviour in multi-channel service distribution

NARCIS (Netherlands)

Heinhuis, D.; de Vries, E.J.; Kundisch, D.; Veit, D.J.; Weitzel, T.; Weinhardt, C.

2009-01-01

Financial service providers are innovating their distribution strategy into multi-channel strategies. The success of a multi-channel approach and the high investments made in information systems and enterprise architectures depends on the adoption and multi-channel usage behaviour of consumers. We

Fundamental studies on initiation and evolution of multi-channel discharges and their application to next generation pulsed power machines.

Energy Technology Data Exchange (ETDEWEB)

Schwarz, Jens; Savage, Mark E.; Lucero, Diego Jose; Jaramillo, Deanna M.; Seals, Kelly Gene; Pitts, Todd Alan; Hautzenroeder, Brenna M.; Laine, Mark Richard; Karelitz, David B.; Porter, John L.

2014-09-01

Future pulsed power systems may rely on linear transformer driver (LTD) technology. The LTD's will be the building blocks for a driver that can deliver higher current than the Z-Machine. The LTD's would require tens of thousands of low inductance ( %3C 85nH), high voltage (200 kV DC) switches with high reliability and long lifetime ( 10 4 shots). Sandia's Z-Machine employs 36 megavolt class switches that are laser triggered by a single channel discharge. This is feasible for tens of switches but the high inductance and short switch life- time associated with the single channel discharge are undesirable for future machines. Thus the fundamental problem is how to lower inductance and losses while increasing switch life- time and reliability. These goals can be achieved by increasing the number of current-carrying channels. The rail gap switch is ideal for this purpose. Although those switches have been extensively studied during the past decades, each effort has only characterized a particular switch. There is no comprehensive understanding of the underlying physics that would allow predictive capability for arbitrary switch geometry. We have studied rail gap switches via an extensive suite of advanced diagnostics in synergy with theoretical physics and advanced modeling capability. Design and topology of multichannel switches as they relate to discharge dynamics are investigated. This involves electrically and optically triggered rail gaps, as well as discrete multi-site switch concepts.

Iterative equalization for OFDM systems over wideband Multi-Scale Multi-Lag channels

NARCIS (Netherlands)

Xu, T.; Tang, Z.; Remis, R.; Leus, G.

2012-01-01

OFDM suffers from inter-carrier interference (ICI) when the channel is time varying. This article seeks to quantify the amount of interference resulting from wideband OFDM channels, which are assumed to follow the multi-scale multi-lag (MSML) model. The MSML channel model results in full channel

Single-electron pulse-height spectra in thin-gap parallel-plate chambers

CERN Document Server

Fonte, Paulo J R; Peskov, Vladimir; Policarpo, Armando

1999-01-01

Single-electron pulse-height spectra were measured in 0.6 and 1.2 mm parallel-plate chambers developed for the TOF system of the ALICE /LHC-HI experiment. Mixtures of Ar with ethane, isobutane, and SF/sub 6/ were studied. The observed spectrum shows a clear peak for all gases, suggesting efficient single-electron detection in thin parallel-plate structures. The pulse-height spectrum can be described by the weighted sum of an exponential and a Polya distribution, the Polya contribution becoming more important at higher gains. Additionally, it was found that the maximum gain, above 10/sup 6/, is limited by the appearance of streamers and depends weakly on the gas composition. The suitability of each mixture for single-electron detection is also quantitatively assessed. (8 refs).

Multi-channel Kondo necklace

Energy Technology Data Exchange (ETDEWEB)

Fazekas, P; Haeyoung, Kee

1993-06-01

A multi-channel generalization of Doniach`s Kondo necklace model is formulated, and its phase diagram studied in the mean-field approximation. Our intention is to introduce the possible simplest model which displays some of the features expected from the overscreened Kondo lattice. The N conduction electron channels are represented by N sets of pseudospins {tau}{sub J}, j = 1 1,..., N which are all antiferromagnetically coupled to a periodic array of modul S = 1/2 spins. Exploiting permutation symmetry in the channel index j allows us to write down the self-consistency equation for general N. For N > 2, we find that the critical temperature is rising with increasing Kondo interaction; we interpret this effect by pointing out that the Kondo coupling creates the composite pseudospin objects which undergo an ordering transition. The relevance of our findings to the underlying fermionic multi-channel problem is discussed. (author). 33 refs, 1 fig.

Study of multi-channel readout ASIC and its discrete module for particle detector

International Nuclear Information System (INIS)

Wang Ke; Fan Lei; Zhang Shengjun; Li Xian

2013-01-01

Recently, kinds of particle detectors have used Application Specific Integrated Circuits (ASIC) in their electronics readout systems, it is the key part for the whole system. This project designed a multi-channel readout ASIC for general detectors. The chip has Preamplifier, Shaper and Peak Detector embedded for easy readout. For each channel, signal which is preprocessed by a low-noise preamplifier is sent to the shaper to form a quasi-Gaussian pulse and keep its peak for readout. This chip and modules of individual Preamplifier, Shaper and Peak Detector have been manufactured and tested. The discrete modules work well, and the 6-channel chip NPRE 6 is ready for test in some particle detection system. (authors)

Formation of plasma channels in air under filamentation of focused ultrashort laser pulses

International Nuclear Information System (INIS)

Ionin, A A; Seleznev, L V; Sunchugasheva, E S

2015-01-01

The formation of plasma channels in air under filamentation of focused ultrashort laser pulses was experimentally and theoretically studied together with theoreticians of the Moscow State University and the Institute of Atmospheric Optics. The influence of various characteristics of ultrashort laser pulses on these plasma channels is discussed. Plasma channels formed under filamentation of focused laser beams with a wavefront distorted by spherical aberration (introduced by adaptive optics) and by astigmatism, with cross-section spatially formed by various diaphragms and with different UV and IR wavelengths, were experimentally and numerically studied. The influence of plasma channels created by a filament of a focused UV or IR femtosecond laser pulse (λ = 248 nm or 740 nm) on characteristics of other plasma channels formed by a femtosecond pulse at the same wavelength following the first one with varied nanosecond time delay was also experimentally studied. An application of plasma channels formed due to the filamentation of focused UV ultrashort laser pulses including a train of such pulses and a combination of ultrashort and long (∼100 ns) laser pulses for triggering and guiding long (∼1 m) electric discharges is discussed. (topical review)

Feasibility study for a multi-channel pulsed radar reflectometer for the jet divertor region

International Nuclear Information System (INIS)

Heijnen, S.H.; Pol, M.J. van de.

1994-09-01

In this report, the feasibility of a pulsed radar system for measuring the electron density profile in the divertor region of JET is studied. Some dedicated experiments are performed with a four-channel system, which was designed for the Rijnhuizen Tokamak Project. To simulate divertor plasmas the measurements are performed in ECRH induced plasmas without current. The parameters of these kinds of plasmas are: n e 19 m -3 , T e <100 eV, and a diameter of ∼30 cm. (HSI)

Multi-channel mechanical test machine for HANARO (I)

International Nuclear Information System (INIS)

Song, M. S.; Choi, Y.; Cho, M. S.; Kim, B. G.; Kang, Y. H.

2004-01-01

Design and fabrication of multi-channel mechanical test machine is useful and important for the study of in-pile test of nuclear materials in HANARO. The dimension and shape of the multi-channel mechanical test machine should be fixed to a test reactor and their objectives. KAERI successfully developed a non-instrumented multi-channel mechanical test machine for material irradiation tests in a domestic research reactor, HANARO. This results in strongly stimulating and accelerating irradiation tests of materials in domestic industry and research fields with HANARO. Although various types of in-pile creep capsule were made for well installation in each test reactor, there is no in-pile creep multi-channel mechanical test machine for HANARO. Hence, the objectives of this study are to fabricate and test a multi-channel mechanical test machine of HANARO

Measurement of the heat transfer coefficient in the dimpled channel: effects of dimple arrangement and channel height

International Nuclear Information System (INIS)

Shin, So Min; Lee, Ki Seon; Park, Seoung Duck; Kwak, Jae Su

2009-01-01

Heat transfer coefficients were measured in a channel with one side dimpled surface. The sphere type dimples were fabricated, and the diameter (D) and the depth of dimple was 16 mm and 4 mm, respectively. Two channel heights of about 0.6D and 1.2D, two dimple configurations were tested. The Reynolds number based on the channel hydraulic diameter was varied from 30000 to 50000. The improved hue detection based transient liquid crystal technique was used in the heat transfer measurement. Heat transfer measurement results showed that high heat transfer was induced downstream of the dimples due to flow reattachment. Due to the flow recirculation on the upstream side in the dimple, the heat transfer coefficient was very low. As the Reynolds increased, the overall heat transfer coefficients also increased. With the same dimple arrangement, the heat transfer coefficients and the thermal performance factors were higher for the lower channel height. As the distance between the dimples became smaller, the overall heat transfer coefficient and the thermal performance factors increased

Organization of pulse-height analysis programs for high event rates

Energy Technology Data Exchange (ETDEWEB)

Cohn, C E [Argonne National Lab., Ill. (USA)

1976-09-01

The ability of a pulse-height analysis program to handle high event rates can be enhanced by organizing it so as to minimize the time spent in interrupt housekeeping. Specifically, the routine that services the data-ready interrupt from the ADC should test whether another event is ready before performing the interrupt return.

Pulse height measurements and electron attachment in drift chambers operated with Xe,CO{sub 2} mixtures

Energy Technology Data Exchange (ETDEWEB)

Andronic, A. E-mail: a.andronic@gsi.de; Appelshaeuser, H.; Blume, C.; Braun-Munzinger, P.; Bucher, D.; Busch, O.; Ramirez, A.C.A. Castillo; Catanescu, V.; Ciobanu, M.; Daues, H.; Devismes, A.; Emschermann, D.; Fateev, O.; Garabatos, C.; Herrmann, N.; Ivanov, M.; Mahmoud, T.; Peitzmann, T.; Petracek, V.; Petrovici, M.; Reygers, K.; Sann, H.; Santo, R.; Schicker, R.; Sedykh, S.; Shimansky, S.; Simon, R.S.; Smykov, L.; Soltveit, H.K.; Stachel, J.; Stelzer, H.; Tsiledakis, G.; Vulpescu, B.; Wessels, J.P.; Windelband, B.; Winkelmann, O.; Xu, C.; Zaudtke, O.; Zanevsky, Yu.; Yurevich, V

2003-02-11

We present pulse height measurements in drift chambers operated with Xe,CO{sub 2} gas mixtures. We investigate the attachment of primary electrons on oxygen and SF{sub 6} contaminants in the detection gas. The measurements are compared with simulations of properties of drifting electrons. We present two methods to check the gas quality: gas chromatography and {sup 55}Fe pulse height measurements using monitor detectors.

Multi-Chromatic Ultrashort Pulse Filamentation and Bulk Modification in Dielectrics

Science.gov (United States)

2016-05-05

AFRL-AFOSR-VA-TR-2016-0194 Multi- Chromatic Ultrashort Pulse Filamentation and Bulk Modification in Dielectrics Jeremy Gulley KENNESAW STATE...Jan 2016 4. TITLE AND SUBTITLE Multi- chromatic Ultrashort Pulse Filamentation and Bulk Modification in Dielectrics 5a. CONTRACT NUMBER 5b. GRANT...in, and modification of, dielectric solids by multi- chromatic ultrashort laser pulses. It was a theoretical effort to develop models of multi

Design and Construction of an Autonomous Low-Cost Pulse Height Analyzer and a Single Channel Analyzer for Moessbauer Spectroscopy

International Nuclear Information System (INIS)

Velasquez, A.A.; Trujillo, J.M.; Morales, A.L.; Tobon, J.E.; Gancedo, J.R.; Reyes, L.

2005-01-01

A multichannel analyzer (MCA) and a single channel-analyzer (SCA) for Moessbauer spectrometry application have been designed and built. Both systems include low-cost digital and analog components. A microcontroller manages, either in PHA or MCS mode, the data acquisition, data storage and setting of the pulse discriminator limits. The user can monitor the system from an external PC through the serial port with the RS232 communication protocol. A graphic interface made with the LabVIEW software allows the user to adjust digitally the lower and upper limits of the pulse discriminator, and to visualize as well as save the PHA spectra in a file. The system has been tested using a 57Co radioactive source and several iron compounds, yielding satisfactory results. The low cost of its design, construction and maintenance make this equipment an attractive choice when assembling a Moessbauer spectrometer

A z-gradient array for simultaneous multi-slice excitation with a single-band RF pulse.

Science.gov (United States)

Ertan, Koray; Taraghinia, Soheil; Sadeghi, Alireza; Atalar, Ergin

2018-07-01

Multi-slice radiofrequency (RF) pulses have higher specific absorption rates, more peak RF power, and longer pulse durations than single-slice RF pulses. Gradient field design techniques using a z-gradient array are investigated for exciting multiple slices with a single-band RF pulse. Two different field design methods are formulated to solve for the required current values of the gradient array elements for the given slice locations. The method requirements are specified, optimization problems are formulated for the minimum current norm and an analytical solution is provided. A 9-channel z-gradient coil array driven by independent, custom-designed gradient amplifiers is used to validate the theory. Performance measures such as normalized slice thickness error, gradient strength per unit norm current, power dissipation, and maximum amplitude of the magnetic field are provided for various slice locations and numbers of slices. Two and 3 slices are excited by a single-band RF pulse in simulations and phantom experiments. The possibility of multi-slice excitation with a single-band RF pulse using a z-gradient array is validated in simulations and phantom experiments. Magn Reson Med 80:400-412, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Multi-pulse shadowgraphic RGB illumination and detection for flow tracking

Science.gov (United States)

Menser, Jan; Schneider, Florian; Dreier, Thomas; Kaiser, Sebastian A.

2018-06-01

This work demonstrates the application of a multi-color LED and a consumer color camera for visualizing phase boundaries in two-phase flows, in particular for particle tracking velocimetry. The LED emits a sequence of short light pulses, red, green, then blue (RGB), and through its color-filter array, the camera captures all three pulses on a single RGB frame. In a backlit configuration, liquid droplets appear as shadows in each color channel. Color reversal and color cross-talk correction yield a series of three frozen-flow images that can be used for further analysis, e.g., determining the droplet velocity by particle tracking. Three example flows are presented, solid particles suspended in water, the penetrating front of a gasoline direct-injection spray, and the liquid break-up region of an "air-assisted" nozzle. Because of the shadowgraphic arrangement, long path lengths through scattering media lower image contrast, while visualization of phase boundaries with high resolution is a strength of this method. Apart from a pulse-and-delay generator, the overall system cost is very low.

Program for the analysis of pulse height spectra and the background from a proportional detector

International Nuclear Information System (INIS)

Flores-Llamas, H.; Yee-Madeira, H.; Contreras-Puente, G.; Zamorano-Ulloa, R.

1991-01-01

A PC-Fortran program is presented for fitting of lineshapes and the analysis of pulse height spectra obtainable with proportional detectors. The common fitting and analysis of pulse height spectra by means of mixed Gaussian lineshapes is readily improved by using Voigt lineshapes. In addition, the background can be evaluated during the fitting process without the need of extra measurements. As an application of the program, a pulse height transmission spectrum accumulated with a static 57 Co source and detected with an argon-metane proportional detector, was least squares fitted to an elaborated complex trial lineshape function containing two Voigt lines plus a straight line. The fitting straight line parameters a and b characterize quantitatively the background. The very good PC-fitting obtained shows that the fitting of experimental spectra with the more realistic Voigt lineshapes is no longer a formidable task and that it is possible to evaluate and subtract the background inherent to the experiment during the fitting process. (orig.)

Investigations of Orchestra Auralizations Using the Multi-Channel Multi-Source Auralization Technique

DEFF Research Database (Denmark)

Vigeant, Michelle; Wang, Lily M.; Rindel, Jens Holger

2008-01-01

a multi-channel multi-source auralization technique, involving individual five-channel anechoic recordings of each instrumental part of two symphonies. In the first study, these auralizations were subjectively compared to orchestra auralizations made using (a) a single omni-directional source, (b......) a surface source, and (c) single-channel multi-source method. Results show that the multi-source auralizations were rated to be more realistic than the surface source ones and to have larger source width than the single omni-directional source auralizations. No significant differences were found between......Room acoustics computer modeling is a tool for generating impulse responses and auralizations from modeled spaces. The auralizations are commonly made from a single-channel anechoic recording of solo instruments. For this investigation, auralizations of an entire orchestra were created using...

Investigation of the Pulse Height Distribution of Boron Trifluoride Proportional Counters

Energy Technology Data Exchange (ETDEWEB)

Andersson, I Oe; Malmskog, S

1962-08-15

The report describes a theoretical and experimental investigation of the factors that determine the pulse height distribution of BF{sub 3}, proportional counters irradiated by thermal neutrons. The branching ratio of the {sup 10}B (n,{alpha}) {sup 7}Li reaction for thermal neutrons has been measured.

A channel profile analyser

International Nuclear Information System (INIS)

Gobbur, S.G.

1983-01-01

It is well understood that due to the wide band noise present in a nuclear analog-to-digital converter, events at the boundaries of adjacent channels are shared. It is a difficult and laborious process to exactly find out the shape of the channels at the boundaries. A simple scheme has been developed for the direct display of channel shape of any type of ADC on a cathode ray oscilliscope display. This has been accomplished by sequentially incrementing the reference voltage of a precision pulse generator by a fraction of a channel and storing ADC data in alternative memory locations of a multichannel pulse height analyser. Alternative channels are needed due to the sharing at the boundaries of channels. In the flat region of the profile alternate memory locations are channels with zero counts and channels with the full scale counts. At the boundaries all memory locations will have counts. The shape of this is a direct display of the channel boundaries. (orig.)

Mimicking multi-channel scattering with single-channel approaches

OpenAIRE

Grishkevich, Sergey; Schneider, Philipp-Immanuel; Vanne, Yulian V.; Saenz, Alejandro

2009-01-01

The collision of two atoms is an intrinsic multi-channel (MC) problem as becomes especially obvious in the presence of Feshbach resonances. Due to its complexity, however, single-channel (SC) approximations, which reproduce the long-range behavior of the open channel, are often applied in calculations. In this work the complete MC problem is solved numerically for the magnetic Feshbach resonances (MFRs) in collisions between generic ultracold 6Li and 87Rb atoms in the ground state and in the ...

Emission spectrochemical determination of boron in steels with pulse height distribution analyzer

International Nuclear Information System (INIS)

Ito, Minao; Sato, Shoki; Fushida, Hiroshi; Narita, Masanao

1983-01-01

The method for rapid determination of total, acid soluble and insoluble boron was established by using emission spectrochemical apparatus equipped with pulse height distribution analyzer. By using the analyzer, emission intensity can be expressed as different level intensity of pulse height distribution. It was made clear that soluble and insoluble boron had different contribution degree to each intensity and that this contribution degree varied at different pre-spark. Therefore, it is necessary for accurate determination of boron that this contribution degree should be corrected by using two intensities, of which contribution degrees are different. It was found on this two intensities method that total and soluble boron corresponded well to 50 % intensities at zero pre-spark and at 2000 pre-spark and that insoluble boron corresponded well to 70 % intensity at zero pre-spark and 50 % intensity at 2000 pre-spark. (author)

A novel time-to-pulse height converter for fast-neutron time-of-flight techniques

International Nuclear Information System (INIS)

Christiansen, J.

1962-01-01

An electronic time-to-pulse height converter is described which uses a multiplicative method instead of the usual one of adding overlapping pulses. This is achieved by a coincidence of a linear sawtooth and a sharply clipped needle-pulse. The sawtooth is fed to the grid of a beam-deflecting tube (E80T) and the needle-pulse is applied to the deflecting plates and opens the tube only during a time-interval of about 5.10 -9 s. The plate gets a charge proportional to the time-difference between the start of the sawtooth and the needle pulse. The plate-pulse is stretched and amplified and its height represents a measurement of the time-difference. With this method we got a time resolution of 2τ = 7 x 10 -12 s with artificial pulses, 2τ = 3 x 10 -10 s with Co 60 γ-coincidences by using NE 102 plastic crystals and 2τ = 1.4 x 10 -9 s with 511-keV γ-coincidences using NaI(Te) crystals. The method was also used with pulsed beam techniques. In this case we got from the pulsing RF an 8-Mc, sharply-peaked pulse-sequence, which was fed to the E80T plates. We had a time-resolution of 2τ = 1.1 x 10 -9 s with 4-MeV neutrons using plastic crystals 0.7 in long. Normally the region of linear response was 30 ns but it was possible to go up to 120 ns. (author) [fr

Essays on Online and Multi-Channel Marketing

OpenAIRE

Zhang, Lingling

2016-01-01

Firms increasingly adopt online and multi-channel marketing strategies to reach and persuade consumers. Therefore, designing an effective marketing mix is critical to their success. The aim of my dissertation is to understand the strategy behind firms’ channel choices and assess marketing effectiveness. It consists of three large-scale empirical studies examining several important aspects of online and multi-channel marketing. My first essay focuses on the business-to-business (B2B) inte...

Multi-channel software defined radio experimental evaluation and analysis

CSIR Research Space (South Africa)

Van der Merwe, JR

2014-09-01

Full Text Available Multi-channel software-defined radios (SDRs) can be utilised as inexpensive prototyping platforms for transceiver arrays. The application for multi-channel prototyping is discussed and measured results of coherent channels for both receiver...

Theoretical research of multi-pulses laser induced damage in dielectrics

International Nuclear Information System (INIS)

Luo Jin; Liu Zhichao; Chen Songlin; Ma Ping

2013-01-01

The pulse width is different, the mechanism of the laser-matter interaction is different. Damage results from plasma formation and ablation forτ≤10 ps and from heat depositing and conventional melting for τ>100 ps. Two theoretical models of transparent dielectrics irradiated by multi-pulses laser are respectively developed based on the above-mentioned different mechanism. One is the dielectric breakdown model based on electron density evolution equation for femtosecond multi-pluses laser, the other is the dielectric heat-damage model based on Fourier's heat exchange equation for nanosecond multi-pluses laser. Using these models, the effects of laser parameters and material parameters on the laser-induced damage threshold of dielectrics are analyzed. The analysis results show that different parameters have different influence on the damage threshold. The effect of parameters on the multi -pulses damage threshold is not entirely the same to the single-pulse damage threshold. The multi-pulses damage mechanism of dielectrics is discussed in detail, considering the effect of different parameters. The discussion provides more information for understanding its damage process and more knowledge to improve its damage thresholds. And the relationship between damage threshold and pulse number is illustrated, it is in good agreement with experimental results. The illustration can help us to predict the multi-pulses damage threshold and the lifetime of optical components. (authors)

The Time Division Multi-Channel Communication Model and the Correlative Protocol Based on Quantum Time Division Multi-Channel Communication

International Nuclear Information System (INIS)

Liu Xiao-Hui; Pei Chang-Xing; Nie Min

2010-01-01

Based on the classical time division multi-channel communication theory, we present a scheme of quantum time-division multi-channel communication (QTDMC). Moreover, the model of quantum time division switch (QTDS) and correlative protocol of QTDMC are proposed. The quantum bit error rate (QBER) is analyzed and the QBER simulation test is performed. The scheme shows that the QTDS can carry out multi-user communication through quantum channel, the QBER can also reach the reliability requirement of communication, and the protocol of QTDMC has high practicability and transplantable. The scheme of QTDS may play an important role in the establishment of quantum communication in a large scale in the future. (general)

Multi-channel data acquisition system for CT

International Nuclear Information System (INIS)

Cao Fuqiang; He Bin; Liu Guohua; Xu Minjian

2009-01-01

The architecture design and realization of a data acquisition system for multi-channel CT is described. The article introduces the conversion of analog signal to digital signal, the data cache and transmission. This data acquisition system can be widely used in the system which requires the multi-channel, weak current signal detection. (authors)

Design and construction of the 8K multi-channel gamma spectrometer module (ADC+MCD)

International Nuclear Information System (INIS)

Vu Xuan Cach; Hoang Thi Ngoc Bich; Truong Van Dat; Pham Ngoc Tuan; Dang Lanh; Tuong Thi Thu Huong; Nguyen Xuan Hai

2007-01-01

A multichannel pulse-height analyzer system (MCA) consists of an ADC with 8192 channel performance, a histogramming memory, and a visual display of the histogram, implemented on a Personal Computer (PC). The purpose of the analog-to-digital converter (ADC) is to measure the maximum amplitude of an analog pulse, and convert that value into a digital number. This digital output is a proportional representation of the analog amplitude at the ADC input. The digital ADC outputs are stored in a histogram memory, where each bin represents a pulse height interval and the number of events in each bin represents the number of events in that interval. The combination of ADC, histogramming memory and display functions are the minimum to constitute a multichannel analyzer or MCA based on PC. It is designed and fabricated on a single NIM module. The communication between MCA module and PC implements via USB bus. In our application, performance of the USB standard version 1.1 is good enough for purposes. The application program was designed in LabWIEW 8.0 software. This application is the main display and acquisition software for the MCA module. It is compatible with Windows 98SE/XP. The libraries USB driver, with their supporting files, are in the FTD2XX driver DLL Package and D2XX function 7.0 for LabWIEW supporting. These libraries are used to write custom code to control the MCA module. The 8K MCA module has the main following hardware specifications: ADC Successive-approximation type with sliding scale linearization; resolution: 8192 channels; dead time per event: 5 μs, including memory transfer; integral nonlinearity: ±0.025% over the top 98% of the dynamic range; differential nonlinearity: < ±1% over the top 98% of the dynamic range; data memory: 224 counts per channel (16 millions counts); presets; Real Time/Live Time: 1 to 232(s), Multiples of 1 s; ADC LLD and ULD Aajustable from 0 to 100% of full scale via hardware control; input accepts positive unipolar pulses in

Single-pulse and multi-pulse femtosecond laser damage of optical single films

International Nuclear Information System (INIS)

Yuan Lei; Zhao Yuan'an; He Hongbo; Shao Jianda; Fan Zhengxiu

2006-01-01

Laser-induced damage of a single 500 nm HfO 2 film and a single 500 nm ZrO 2 film were studied with single- and multi-pulse femtosecond laser. The laser-induced damage thresholds (LIDT) of both samples by the 1-on-1 method and the 1000-on-1 method were reported. It was discovered that the LIDT of the HfO 2 single film was higher than that of the ZrO 2 single film by both test methods, which was explained by simple Keldysh's multiphoton ionization theory. The LIDT of multi-pulse was lower than that of single-pulse for both samples as a result of accumulative effect. (authors)

Design and Construction of an Autonomous Low-Cost Pulse Height Analyzer and a Single Channel Analyzer for Mössbauer Spectroscopy

Science.gov (United States)

Velásquez, A. A.; Gancedo, J. R.; Trujillo, J. M.; Morales, A. L.; Tobón, J. E.; Reyes, L.

2005-04-01

A multichannel analyzer (MCA) and a single channel-analyzer (SCA) for Mössbauer spectrometry application have been designed and built. Both systems include low-cost digital and analog components. A microcontroller manages, either in PHA or MCS mode, the data acquisition, data storage and setting of the pulse discriminator limits. The user can monitor the system from an external PC through the serial port with the RS232 communication protocol. A graphic interface made with the LabVIEW software allows the user to adjust digitally the lower and upper limits of the pulse discriminator, and to visualize as well as save the PHA spectra in a file. The system has been tested using a 57Co radioactive source and several iron compounds, yielding satisfactory results. The low cost of its design, construction and maintenance make this equipment an attractive choice when assembling a Mössbauer spectrometer.

Computer-based multi-channel analyzer based on internet

International Nuclear Information System (INIS)

Zhou Xinzhi; Ning Jiaoxian

2001-01-01

Combined the technology of Internet with computer-based multi-channel analyzer, a new kind of computer-based multi-channel analyzer system which is based on browser is presented. Its framework and principle as well as its implementation are discussed

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping

2016-05-18

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping; Wu, Ying; Lai, Yun

2016-01-01

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Baseline distortion effect on gamma-ray pulse-height spectra in neutron capture experiments

International Nuclear Information System (INIS)

Laptev, A.; Harada, H.; Nakamura, S.; Hori, J.; Igashira, M.; Ohsaki, T.; Ohgama, K.

2005-01-01

A baseline distortion effect due to gamma-flash at neutron time-of-flight measurement using a pulse neutron source has been investigated. Pulses from C 6 D 6 detectors accumulated by flash-ADC were processed with both standard analog-to-digital converter (ADC) and flash-ADC operational modes. A correction factor of gamma-ray yields, due to baseline shift, was quantitatively obtained by comparing the pulse height spectra of the two data-taking modes. The magnitude of the correction factor depends on the time after gamma-flash and has complex time dependence with a changing sign

Self-channeling of high-power laser pulses through strong atmospheric turbulence

Science.gov (United States)

Peñano, J.; Palastro, J. P.; Hafizi, B.; Helle, M. H.; DiComo, G. P.

2017-07-01

We present an unusual example of truly long-range propagation of high-power laser pulses through strong atmospheric turbulence. A form of nonlinear self-channeling is achieved when the laser power is close to the self-focusing power of air and the transverse dimensions of the pulse are smaller than the coherence diameter of turbulence. In this mode, nonlinear self-focusing counteracts diffraction, and turbulence-induced spreading is greatly reduced. Furthermore, the laser intensity is below the ionization threshold so that multiphoton absorption and plasma defocusing are avoided. Simulations show that the pulse can propagate many Rayleigh lengths (several kilometers) while maintaining a high intensity. In the presence of aerosols, or other extinction mechanisms that deplete laser energy, the pulse can be chirped to maintain the channeling.

Derivation of pulse height to exposure rate conversion functions for aerial radiological surveys

International Nuclear Information System (INIS)

Artuso, J.F.

1985-01-01

A method is described for deriving conversion functions that can be used to convert pulse height spectra taken at altitude to the exposure rate at the 1-m level. An integral equation is set up which involves the integration of a calculated pulse height spectrum multiplied by an unknown conversion function and then set equal to the exposure rate at ground level. This equation is then solved for the conversion function by assuming as a solution a three-term polynomial. Conversion functions have been derived for various source distributions, including surface, uniform, and exponentially distributed sources. These conversion functions are independent of source energy, which means that a conversion can be made without any knowledge of the isotopic content of the source. In the case of a uniform distribution, these conversion functions provide conversions that agree to within 10% with ground truth measurements

Some studies on the pulse-height loss due to capacitive decay in the detector-circuit of parallel plate ionization chambers

International Nuclear Information System (INIS)

Sharma, S.L.; Anil Kumar, G.; Choudhury, R.K.

2006-01-01

Pulse-type ionization chambers are invariably operated in the electron-sensitive mode where the capacitive decay in the detector-circuit during the electron collection produces loss in the pulse-height. In order to understand and appreciate the effect of this capacitive decay on the detector response, we have carried out Monte Carlo simulations of the response of two-electrode parallel plate ionization chambers with and without the capacitive decay keeping shaping time so large that the ballistic deficit is negligibly small. These simulations have been carried out incorporating the physical processes, namely, emission of charged particles from a point radioactive source, the generation of charge carriers in the active volume, separation and acceleration of the charge carriers, transport of the charge carriers, induction of charges on the electrodes, pulse processing by preamplifier-amplifier network, etc. These simulations have shown that the concerned capacitive decay produces appreciable loss in the pulse-height, if the detector-circuit time constant is of the order of maximum electron collection time. We have also carried out measurements on the pulse-height loss due to the capacitive decay in the detector-circuit during the electron collection for a two-electrode parallel plate ionization chamber. The experimental data on the pulse-height loss match reasonably well with the theoretical predictions

Burst pressure of phaseguide structures of different heights in all-polymer microfluidic channels

DEFF Research Database (Denmark)

Garbarino, Francesca; Kistrup, Kasper; Rizzi, Giovanni

2017-01-01

We present an experimental investigation of the burst/overflow pressure of water and a representative surfactant-containing buffer in microfluidic channels with phaseguide structures oriented at an angle of 90° to the channel length as a function of their height, . The all-polymer chips were...... structures were found able to pin both liquids and the burst pressure was found to increase approximately linearly with the height of the phaseguide from about 100–350 Pa for water and from about 25–200 Pa for the buffer. The burst pressure was found not to depend on the channel width and it was only weakly...... influenced by the presence of a branch on the phaseguide. For phaseguides with a branch, the liquid was always found to burst at the branch location. The measured burst pressures were compared to those estimated using a simple theory. The knowledge obtained in this study enables simple tuning of liquid...

Single- and multi-pulse femtosecond laser ablation of optical filter materials

International Nuclear Information System (INIS)

Krueger, J.; Lenzner, M.; Martin, S.; Lenner, M.; Spielmann, C.; Fiedler, A.; Kautek, W.

2003-01-01

Ablation experiments employing Ti:sapphire laser pulses with durations from 30 to 340 fs (centre wavelength 800 nm, repetition rate 1 kHz) were performed in air. Absorbing filters (Schott BG18 and BG36) served as targets. The direct focusing technique was used under single- and multi-pulse irradiation conditions. Ablation threshold fluences were determined from a semi-logarithmic plot of the ablation crater diameter versus laser fluence. The threshold fluence decreases for a shorter pulse duration and an increasing number of pulses. The multi-pulse ablation threshold fluences are similar to those of undoped glass material (∼1 J cm -2 ). That means that the multi-pulse ablation threshold is independent on the doping level of the filters. For more than 100 pulses per spot and all pulse durations applied, the threshold fluence is practically constant. This leads to technically relevant ablation threshold values

A new method for multi-channel Fabry-Perot spectroscopy of light pulses in the nanosecond regime

International Nuclear Information System (INIS)

Behn, R.

1975-01-01

The demand for powerful multichannel spectrometers raised, e.g., in laser scattering plasma diagnostics, gave rise to the question if it would not be possible to avoid the light losses occuring in the use of multichannel Fabry-Perot spectrometers. These losses can be avoided with the technique presented here. The reflected light is collected and fed back to the interferometer at a different angle. It can thus be recovered for registration in another spectral channel. This method is particularly suitable for the investigation of short light pulses. A spectrum can thus be scanned step by step with full utilization of the transit time of the light pulse. In addition to light recovery, there is another advantage in that only one detector is used for multichannel analysis, thus eliminating calibration problems. In the annex to the report, emission spectres of different dye laser versions are presented and explained. (orig./GG) [de

Development of multi-channel high power rectangular RF window for LHCD system employing high temperature vacuum brazing technique

International Nuclear Information System (INIS)

Sharma, P K; Ambulkar, K K; Parmar, P R; Virani, C G; Thakur, A L; Joshi, L M; Nangru, S C

2010-01-01

A 3.7 GHz., 120 kW (pulsed), lower hybrid current drive (LHCD) system is employed to drive non-inductive plasma current in ADITYA tokamak. The rf power is coupled to the plasma through grill antenna and is placed in vacuum environment. A vacuum break between the pressurized transmission line and the grill antenna is achieved with the help of a multi (eight) channel rectangular RF vacuum window. The phasing between adjacent channels of 8-channel window (arranged in two rows) is important for launching lower hybrid waves and each channel should have independent vacuum window so that phase information is retained. The geometrical parameter of the grill antenna, like periodicity (9mm), channel dimensions (cross sectional dimension of 76mm x 7mm), etc. is to be maintained. These design constraint demanded a development of a multi channel rectangular RF vacuum window. To handle rf losses and thermal effects, high temperature vacuum brazing techniques is desired. Based on the above requirements we have successfully developed a multi channel rectangular rf vacuum window employing high temperature vacuum brazing technique. During the development process we could optimize the chemical processing parameters, brazing process parameters, jigs and fixtures for high temperature brazing and leak testing, etc. Finally the window is tested for low power rf performance using VNA. In this paper we would present the development of the said window in detail along with its mechanical, vacuum and rf performances.

Development of multi-channel high power rectangular RF window for LHCD system employing high temperature vacuum brazing technique

Energy Technology Data Exchange (ETDEWEB)

Sharma, P K; Ambulkar, K K; Parmar, P R; Virani, C G; Thakur, A L [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Joshi, L M; Nangru, S C, E-mail: pramod@ipr.res.i [Central Electronics Engineering Research Institute, Pilani, Rajasthan 333 031 (India)

2010-02-01

A 3.7 GHz., 120 kW (pulsed), lower hybrid current drive (LHCD) system is employed to drive non-inductive plasma current in ADITYA tokamak. The rf power is coupled to the plasma through grill antenna and is placed in vacuum environment. A vacuum break between the pressurized transmission line and the grill antenna is achieved with the help of a multi (eight) channel rectangular RF vacuum window. The phasing between adjacent channels of 8-channel window (arranged in two rows) is important for launching lower hybrid waves and each channel should have independent vacuum window so that phase information is retained. The geometrical parameter of the grill antenna, like periodicity (9mm), channel dimensions (cross sectional dimension of 76mm x 7mm), etc. is to be maintained. These design constraint demanded a development of a multi channel rectangular RF vacuum window. To handle rf losses and thermal effects, high temperature vacuum brazing techniques is desired. Based on the above requirements we have successfully developed a multi channel rectangular rf vacuum window employing high temperature vacuum brazing technique. During the development process we could optimize the chemical processing parameters, brazing process parameters, jigs and fixtures for high temperature brazing and leak testing, etc. Finally the window is tested for low power rf performance using VNA. In this paper we would present the development of the said window in detail along with its mechanical, vacuum and rf performances.

Simulation analysis of impulse characteristics of space debris irradiated by multi-pulse laser

Science.gov (United States)

Lin, Zhengguo; Jin, Xing; Chang, Hao; You, Xiangyu

2018-02-01

Cleaning space debris with laser is a hot topic in the field of space security research. Impulse characteristics are the basis of cleaning space debris with laser. In order to study the impulse characteristics of rotating irregular space debris irradiated by multi-pulse laser, the impulse calculation method of rotating space debris irradiated by multi-pulse laser is established based on the area matrix method. The calculation method of impulse and impulsive moment under multi-pulse irradiation is given. The calculation process of total impulse under multi-pulse irradiation is analyzed. With a typical non-planar space debris (cube) as example, the impulse characteristics of space debris irradiated by multi-pulse laser are simulated and analyzed. The effects of initial angular velocity, spot size and pulse frequency on impulse characteristics are investigated.

Enhanced propagation for relativistic laser pulses in inhomogeneous plasmas using hollow channels.

Science.gov (United States)

Fuchs, J; d'Humières, E; Sentoku, Y; Antici, P; Atzeni, S; Bandulet, H; Depierreux, S; Labaune, C; Schiavi, A

2010-11-26

The influence of long (several millimeters) and hollow channels, bored in inhomogeneous ionized plasma by using a long pulse laser beam, on the propagation of short, ultraintense laser pulses has been studied. Compared to the case without a channel, propagation in channels significantly improves beam transmission and maintains a beam quality close to propagation in vacuum. In addition, the growth of the forward-Raman instability is strongly reduced. These results are beneficial for the direct scheme of the fast ignitor concept of inertial confinement fusion as we demonstrate, in fast-ignition-relevant conditions, that with such channels laser energy can be carried through increasingly dense plasmas close to the fuel core with minimal losses.

Fabrication of Multi-Harmonic Buncher for Pulsed Proton Beam Generation

Energy Technology Data Exchange (ETDEWEB)

Kim, H. S.; Kwon, H. J.; Cho, Y. S. [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

2015-05-15

Fast neutrons with a broad spectrum can be generated by irradiating the proton beams on target materials. To measure the neutron energy by time of flight (TOF) method, the short pulse width of the proton beam is preferred because the neutron energy uncertainty is proportional to the pulse width. In addition, the pulse repetition rate should be low enough to extend the lower limit of the available neutron energy. Pulsed proton beam generation system is designed based on an electrostatic deflector and slit system as shown in Fig. 1. In a simple deflector with slit system, most of the proton beam is blocked by slit, especially when the beam pulse width is short. The ideal field pattern inside the buncher cavity is saw-tooth wave. To make the field pattern similar to the saw-tooth waveform, we adopted a multi-harmonic buncher (MHB). The design for the multi-harmonic buncher including 3D electromagnetic calculation has been performed. Based on the design, a multi-harmonic buncher cavity was fabricated. It consists of two resonators, two drift tubes and a vacuum chamber. The resonator is a quarter-wave coaxial resonator type. The drift tube is connected to the resonator by using a coaxial vacuum feedthrough. Design summary and detailed fabrication method of the multi-harmonic buncher is presented in this paper. A multi-harmonic buncher for a proton beam chopper system to generate a short pulse neutron beam was designed, fabricated and assembled.

Effect of Aspect Ratio, Channel Orientation, Rib Pitch-to-Height Ratio, and Number of Ribbed Walls on Pressure Drop Characteristics in a Rotating Channel with Detached Ribs

Directory of Open Access Journals (Sweden)

K. Arun

2007-01-01

Full Text Available The present work involves experimental investigation of the effects of aspect ratio, channel orientation angle, rib pitch-to-height ratio (P/e, and number of ribbed walls on friction factor in orthogonally rotating channel with detached ribs. The ribs are separated from the base wall to provide a small region of flow between the base wall and the ribs. Experiments have been conducted at Reynolds number ranging from 10000–17000 with rotation numbers varying from 0–0.38. Pitch-to-rib height ratios (P/e of 5 and 10 at constant rib height-to-hydraulic diameter ratio (e/D of 0.1 and a clearance ratio (C/e of 0.38 are considered. The rib angle of attack with respect to mainstream flow is 90∘. The channel orientation at which the ribbed wall becomes trailing surface (pressure side on which the Coriolis force acts is considered as the 0∘ orientation angle. For one-wall ribbed case, channel is oriented from 0∘ to 180∘ about its axis in steps of 30∘ to change the orientation angle. For two-wall ribbed case, the orientation angle is changed from 0∘ to 90∘ in steps of 30∘. Friction factors for the detached ribbed channels are compared with the corresponding attached ribbed channel. It is found that in one-wall detached ribbed channel, increase in the friction factor ratio with the orientation angle is lower for rectangular channel compared to that of square channel for both the pitch-to-rib height ratios of 5 and 10 at a given Reynolds number and rotation number. Friction factor ratios of two-wall detached ribbed rectangular channel are comparable with corresponding two-wall detached ribbed square channel both under stationary and rotating conditions.

Multi-channel phase-equivalent transformation and supersymmetry

OpenAIRE

Shirokov, A. M.; Sidorenko, V. N.

2000-01-01

Phase-equivalent transformation of local interaction is generalized to the multi-channel case. Generally, the transformation does not change the number of the bound states in the system and their energies. However, with a special choice of the parameters, the transformation removes one of the bound states and is equivalent to the multi-channel supersymmetry transformation recently suggested by Sparenberg and Baye. Using the transformation, it is also possible to add a bound state to the discr...

Inorganic nanocomposite films with polymer nanofillers made by the concurrent multi-beam multi-target pulsed laser deposition

Science.gov (United States)

Darwish, Abdalla M.; Sarkisov, Sergey S.; Mele, Paolo; Saini, Shrikant; Moore, Shaelynn; Bastian, Tyler; Dorlus, Wydglif; Zhang, Xiaodong; Koplitz, Brent

2017-08-01

We report on the new class of inorganic nanocomposite films with the inorganic phase hosting the polymer nanofillers made by the concurrent multi-beam multi-target pulsed laser deposition of the inorganic target material and matrix assisted pulsed laser evaporation of the polymer (MBMT-PLD/MAPLE). We used the exemplary nanocomposite thermoelectric films of aluminum-doped ZnO known as AZO with the nanofillers made of poly(methyl methacrylate) known as PMMA on various substrates such as SrTiO3, sapphire, fused silica, and polyimide. The AZO target was ablated with the second harmonic (532 nm) of the Nd:YAG Q-switched laser while PMMA was evaporated from its solution in chlorobenzene frozen in liquid nitrogen with the fundamental harmonic (1064 nm) of the same laser (50 Hz pulse repetition rate). The introduction of the polymer nanofillers increased the electrical conductivity of the nanocomposite films (possibly due to the carbonization of PMMA and the creation of additional channels of electric current) three times and reduced the thermal conductivity by 1.25 times as compared to the pure AZO films. Accordingly, the increase of the thermoelectric figure-of merit ZT would be 4 times. The best performance was observed for the sapphire substrates where the films were the most uniform. The results point to a huge potential of the optimization of a broad variety of optical, opto-electronic, and solar-power nanocomposite inorganic films by the controllable introduction of the polymer nanofillers using the MBMT-PLD/MAPLE method.

The Buywell Way: seven essential practices of a highly successful multi-channel e-tailer

Directory of Open Access Journals (Sweden)

Mary Tate

2005-05-01

Full Text Available After the dot-com bust there is considerable evidence that multi-channel retailers are more successful than purely on-line retailers. Multi-channel retailing is becoming mainstream and considerable research exists on successful multi-channel strategies. Despite this, some organisations are having more success than others with their multi-channel approach. We talked to the management of one of Australasia’s most successful multi-channel apparel and home-ware retailers about the theory and practice of multi-channel retailing, with the aim of building on existing theory in multi-channel e-commerce.

Pulse-height response of silicon surface-barrier detectors to high-energy heavy ions

International Nuclear Information System (INIS)

Smith, G.D.

1973-01-01

The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions ( 32 S, 35 Cl) and heavy target recoils (Ni, Cu, 98 Mo, Ag, Au) at sufficient energies to produce a significant recombination defect. The results confirm the existence of a recombination zone at the front surface of these detectors and the significance of plasma recombination as a portion of the pulse-height defect. (Diss. Abstr. Int., B)

Relativistic Channeling of a Picosecond Laser Pulse in a Near-Critical Preformed Plasma

International Nuclear Information System (INIS)

Borghesi, M.; MacKinnon, A.J.; Barringer, L.; Gaillard, R.; Gizzi, L.; Meyer, C.; Willi, O.; Pukhov, A.; Meyer-ter-Vehn, J.

1997-01-01

Relativistic self-channeling of a picosecond laser pulse in a preformed plasma near critical density has been observed both experimentally and in 3D particle-in-cell simulations. Optical probing measurements indicate the formation of a single pulsating propagation channel, typically of about 5μm in diameter. The computational results reveal the importance in the channel formation of relativistic electrons traveling with the light pulse and of the corresponding self-generated magnetic field. copyright 1997 The American Physical Society

Design And Construction Of The 8K Multi-Channel GAMMA Spectrometer Module (AMPLIFIER+ADC+MCD)

International Nuclear Information System (INIS)

Truong Van Dat; Hoang Thi Ngoc Bich; Pham Ngoc Tuan; Dang Lanh; Tuong Thi Thu Huong; Vu Xuan Cach

2007-01-01

A multichannel pulse-height analyzer system (MCA) consists of an spectroscopy Amplifier, ADC with 8192 channel performance, a histogramming memory, and a visual display of the histogram implemented on a Personal Computer (PC). The purpose of the analog-to-digital converter (ADC) is to measure the maximum amplitude of an analog pulse, and convert that value into a digital number. This digital output is a proportional representation of the analog amplitude at the ADC input. The digital ADC outputs are stored in a histogram memory, where each bin represents a pulse height interval and the number of events in each bin represents the number of events in that interval. The combination of ADC, histogramming memory and display functions are the minimum to constitute a multichannel analyzer or MCA based on PC. It is designed and fabricated on a single NIM module. The communication between MCA module and PC implements via USB bus. In our application, performance of the USB standard version 1.1 is good enough for purposes. The application program was designed in LabWIEW 8.0 software. This application is the main display and acquisition software for the MCA module. It is compatible with Windows 98SE/XP. The libraries USB driver, with their supporting files, are in the FTD2XX driver DLL Package and D2XX function 7.0 for LabWIEW supporting. These libraries are used to write custom code to control the MCA module. (author)

An optimal multi-channel memory controller for real-time systems

NARCIS (Netherlands)

Gomony, M.D.; Akesson, K.B.; Goossens, K.G.W.

2013-01-01

Optimal utilization of a multi-channel memory, such as Wide IO DRAM, as shared memory in multi-processor platforms depends on the mapping of memory clients to the memory channels, the granularity at which the memory requests are interleaved in each channel, and the bandwidth and memory capacity

Evaluation of dynamic range for LLNL streak cameras using high contrast pulsed and pulse podiatry on the Nova laser system

International Nuclear Information System (INIS)

Richards, J.B.; Weiland, T.L.; Prior, J.A.

1990-01-01

This paper reports on a standard LLNL streak camera that has been used to analyze high contrast pulses on the Nova laser facility. These pulses have a plateau at their leading edge (foot) with an amplitude which is approximately 1% of the maximum pulse height. Relying on other features of the pulses and on signal multiplexing, we were able to determine how accurately the foot amplitude was being represented by the camera. Results indicate that the useful single channel dynamic range of the instrument approaches 100:1

16-channel analog store and multiplexer unit

Energy Technology Data Exchange (ETDEWEB)

Brossard, M; Kulka, Z [Clermont-Ferrand-2 Univ., 63 - Aubiere (France). Lab. de Physique Corpusculaire

1979-03-15

A 16-channel analog store and multiplexer unit is described. The unit enables storing and selection of analog information which is then digitally encoded by single ADC. This solution becomes economically attractive particularly in multidetector pulse height analysis systems.

Channeling and stability of laser pulses in plasmas

International Nuclear Information System (INIS)

Sprangle, P.; Krall, J.; Esarey, E.

1995-01-01

A laser pulse propagating in a plasma is found to undergo a combination of hose and modulation instabilities. The coupled equations for the laser beam envelope and centroid are derived and solved for a laser pulse of finite length propagating through either a uniform plasma or preformed plasma density channel. The laser envelope equation describes the pulse self-focusing and optical guiding in plasmas and is used to analyze the self-modulation instability. The laser centroid equation describes the transverse motion of the laser pulse (hosing) in plasmas. Significant coupling between the centroid and envelope motion as well as harmonic generation in the envelope can occur. In addition, the transverse profile of the generated wake field is strongly affected by the laser hose instability. Methods to reduce the laser hose instability are demonstrated. copyright 1995 American Institute of Physics

Interference-aware power control for multi-radio multi-channel wireless mesh networks

CSIR Research Space (South Africa)

Olwal, TO

2009-09-01

Full Text Available are well known in [9], [6]. The operation of multi-radio multi-channel (MRMC) WMNs generally requires sustainable energy supply. Substantial deployments of WMNs have recently been witnessed in rural and remote communities [4]. In such applications...]. Power resources are dynamically adjusted by each NIC using intra and inter-subsystem (channel) states. Due to the decentralized nature, each MP assumes imperfect knowledge about the global network. Further we assume that there exists...

Ground level cosmic ray pulse height spectrum of a 7. 5 cm diameter spherical NaI(Tl) scintillation detector for energy region below 5 MeV

Energy Technology Data Exchange (ETDEWEB)

Nagaoka, Toshi; Saito, Kimiaki; Moriuchi, Shigeru

1988-09-01

Ground level cosmic ray pulse height spectrum of a 7.5 cm diameter spherical NaI(Tl) scintillation detector was evaluated through stripping operation based on a pulse height spectrum measured on the sea and high precision response functions of the detector for U-series, Th-series and /sup 40/K. The exposure rate calculated from the determined cosmic ray pulse height spectrum was 0.21 R/h eq., which agreed well with that obtained from another method. The shape of the pulse height spectrum showed similarity to that measured at the altitude of 16,000 ft, especially in the energy region of 0 to 3 MeV. The principle of the adopted method is rather plain, however, the reliability of the spectrum is satisfactory. As the pulse height spectrum is a common information to any analytical method for environmental gamma ray using NaI(Tl) scintillation detector, it is expected to be used for simple and precise separation of cosmic ray component involved in the enviromental pulse height spectrum.

Ground level cosmic ray pulse height spectrum of a 7.5 cm diameter spherical NaI(Tl) scintillation detector for energy region below 5 MeV

International Nuclear Information System (INIS)

Nagaoka, Toshi; Saito, Kimiaki; Moriuchi, Shigeru

1988-01-01

Ground level cosmic ray pulse height spectrum of a 7.5 cm diameter spherical NaI(Tl) scintillation detector was evaluated through stripping operation based on a pulse height spectrum measured on the sea and high precision response functions of the detector for U-series, Th-series and 40 K. The exposure rate calculated from the determined cosmic ray pulse height spectrum was 0.21 μR/h eq., which agreed well with that obtained from another method. The shape of the pulse height spectrum showed similarity to that measured at the altitude of 16,000 ft, especially in the energy region of 0 to 3 MeV. The principle of the adopted method is rather plain, however, the reliability of the spectrum is satisfactory. As the pulse height spectrum is a common information to any analytical method for environmental gamma ray using NaI(Tl) scintillation detector, it is expected to be used for simple and precise separation of cosmic ray component involved in the enviromental pulse height spectrum. (author)

Independent multi-channel analyzer with the color display and microcomputer in the CAMAC standard

International Nuclear Information System (INIS)

Gyunter, Z.; Elizarov, O.I.; Zhukov, G.P.; Mikhaehlis, B.; Shul'tts, K.Kh.

1983-01-01

An independent multi-channel time-of-flight analyzer developed for a spectrometer of polarised neutrons and used in experiments with the IBR-2 pulse reactor is described. Different cyclic modes of measuring are realized in the analyzer, 4 kwords of analyzer momory being assigned for each mode. The spectra are displayed on a colour screen during measurements. Simultaneous displaying of up to 8 spectra is possible. A microcomputer transfers the spectra from the buffer analyzer memory to the microcomputer memory. The accumulated information is transferred to the PDP-11/70 central computer

Generation of electromagnetic pulses from plasma channels induced by femtosecond light strings

OpenAIRE

Cheng, Chung-Chieh; Wright, E. M.; Moloney, J. V.

2000-01-01

We present a model that elucidates the physics underlying the generation of an electromagnetic pulse from a femtosecond laser induced plasma channel. The radiation pressure force from the laser pulse spatially separates the ionized electrons from the heavier ions and the induced dipole moment subsequently oscillates at the plasma frequency and radiates an electromagnetic pulse.

Determination of optimum "multi-channel surface wave method" field parameters.

Science.gov (United States)

2012-12-01

Multi-channel surface wave methods (especially the multi-channel analyses of surface wave method; MASW) are routinely used to : determine the shear-wave velocity of the subsurface to depths of 100 feet for site classification purposes. Users are awar...

Skyrmion-based multi-channel racetrack

Science.gov (United States)

Song, Chengkun; Jin, Chendong; Wang, Jinshuai; Xia, Haiyan; Wang, Jianbo; Liu, Qingfang

2017-11-01

Magnetic skyrmions are promising for the application of racetrack memories, logic gates, and other nano-devices, owing to their topologically protected stability, small size, and low driving current. In this work, we propose a skyrmion-based multi-channel racetrack memory where the skyrmion moves in the selected channel by applying voltage-controlled magnetic anisotropy gates. It is demonstrated numerically that a current-dependent skyrmion Hall effect can be restrained by the additional potential of the voltage-controlled region, and the skyrmion velocity and moving channel in the racetrack can be operated by tuning the voltage-controlled magnetic anisotropy, gate position, and current density. Our results offer a potential application of racetrack memory based on skyrmions.

Multi-Channel Maximum Likelihood Pitch Estimation

DEFF Research Database (Denmark)

Christensen, Mads Græsbøll

2012-01-01

In this paper, a method for multi-channel pitch estimation is proposed. The method is a maximum likelihood estimator and is based on a parametric model where the signals in the various channels share the same fundamental frequency but can have different amplitudes, phases, and noise characteristics....... This essentially means that the model allows for different conditions in the various channels, like different signal-to-noise ratios, microphone characteristics and reverberation. Moreover, the method does not assume that a certain array structure is used but rather relies on a more general model and is hence...

Multi-Channel Deconvolution for Forward-Looking Phase Array Radar Imaging

Directory of Open Access Journals (Sweden)

Jie Xia

2017-07-01

Full Text Available The cross-range resolution of forward-looking phase array radar (PAR is limited by the effective antenna beamwidth since the azimuth echo is the convolution of antenna pattern and targets’ backscattering coefficients. Therefore, deconvolution algorithms are proposed to improve the imaging resolution under the limited antenna beamwidth. However, as a typical inverse problem, deconvolution is essentially a highly ill-posed problem which is sensitive to noise and cannot ensure a reliable and robust estimation. In this paper, multi-channel deconvolution is proposed for improving the performance of deconvolution, which intends to considerably alleviate the ill-posed problem of single-channel deconvolution. To depict the performance improvement obtained by multi-channel more effectively, evaluation parameters are generalized to characterize the angular spectrum of antenna pattern or singular value distribution of observation matrix, which are conducted to compare different deconvolution systems. Here we present two multi-channel deconvolution algorithms which improve upon the traditional deconvolution algorithms via combining with multi-channel technique. Extensive simulations and experimental results based on real data are presented to verify the effectiveness of the proposed imaging methods.

Recent advances in Multi-Channel Algebraic Scattering

International Nuclear Information System (INIS)

Karataglidis, S.; Fraser, P. R.; Amos, K.; Canton, L.; Pisent, G.; Svenne, J. P.; Knijff, D. van der

2011-01-01

For coupled-channel descriptions of low-energy nucleon-induced interactions involving nuclei with particle-unstable exited states, it is necessary to include the widths of the target states. How those widths may affect the elastic scattering cross sections is examined within the framework of the Multi-Channel Algebraic Scattering (MCAS) method.

Evaluation of Multi-Channel ADCs for Gamma-Ray Spectroscopy

Science.gov (United States)

Tan, Hui; Hennig, Wolfgang; Walby, Mark D.; Breus, Dimitry; Harris, Jackson

2013-04-01

As nuclear physicists increasingly design large scale experiments with hundreds or thousands of detector channels, there are growing needs for high density readout electronics with good timing and energy resolution that at the same time offer lower cost per channel compared to existing commercial solutions. Recent improvements in the design of commercial analog to digital converters (ADCs) have resulted in a variety of multi-channel ADCs that are natural choice for designing such high density readout modules. However, multi-channel ADCs typically are designed for medical imaging/ultrasound applications and therefore are not rated for their spectroscopic characteristics. In this work, we evaluated the gamma-ray spectroscopic performance of several multi-channel ADCs, including their energy resolution, nonlinearity, and timing resolution. Some of these ADCs demonstrated excellent energy resolution, 2.66% FWHM at 662 keV with a LaBr3 or 1.78 keV FWHM at 1332.5 keV with a high purity germanium (HPGe) detector, and sub-nanosecond timing resolution with LaBr 3. We present results from these measurements to illustrate their suitability for gamma-ray spectroscopy.

Evaluation of dynamic range for LLNL streak cameras using high contrast pulses and pulse podiatry'' on the Nova laser system

Energy Technology Data Exchange (ETDEWEB)

Richards, J.B.; Weiland, T.L.; Prior, J.A.

1990-07-01

A standard LLNL streak camera has been used to analyze high contrast pulses on the Nova laser facility. These pulses have a plateau at their leading edge (foot) with an amplitude which is approximately 1% of the maximum pulse height. Relying on other features of the pulses and on signal multiplexing, we were able to determine how accurately the foot amplitude was being represented by the camera. Results indicate that the useful single channel dynamic range of the instrument approaches 100:1. 1 ref., 4 figs., 1 tab.

Autonomous transmission power adaptation for multi-radio multi-channel wireless mesh networks

CSIR Research Space (South Africa)

Olwal, TO

2009-09-01

Full Text Available Multi-Radio Multi-Channel (MRMC) systems are key to power control problems in WMNs. Previous studies have emphasized through- put maximization in such systems as the main design challenge and transmission power control treated as a secondary issue...

Autonomous transmission power adaptation for multi-radio multi-channel wireless mesh networks

CSIR Research Space (South Africa)

Olwal, TO

2008-09-01

Full Text Available Multi-Radio Multi-Channel (MRMC) systems are key to power control problems in WMNs. Previous studies have emphasized throughput maximization in such systems as the main design challenge and transmission power control treated as a secondary issue...

A peak value searching method of the MCA based on digital logic devices

International Nuclear Information System (INIS)

Sang Ziru; Huang Shanshan; Chen Lian; Jin Ge

2010-01-01

Digital multi-channel analyzers play a more important role in multi-channel pulse height analysis technique. The direction of digitalization are characterized by powerful pulse processing ability, high throughput, improved stability and flexibility. This paper introduces a method of searching peak value of waveform based on digital logic with FPGA. This method reduce the dead time. Then data correction offline can improvement the non-linearity of MCA. It gives the α energy spectrum of 241 Am. (authors)

Robust, highly customizable, and economical multi-channel electrode for chronic multi-unit recording in behaving animals.

Science.gov (United States)

Tateyama, Yukina; Oyama, Kei; Shiraishi, Masaru; Iijima, Toshio; Tsutsui, Ken-Ichiro

2017-12-01

Multi-unit recording has been one of the most widely used techniques to investigate the correlation between multiple neuronal activities and behavior. However, a common problem of currently used multi-channel electrodes is their physical weakness. In this study, we developed a novel multi-channel electrode with sufficient physical strength to penetrate a thickened dura mater. This electrode consists of low-cost materials and is easily fabricated, and it enables recording without removing dura mater, thereby reducing the risk of inflammation, infection, or brain herniation. The low-cost multi-channel electrode developed in this study would be a useful tool for chronic recording in behaving animals. Copyright © 2017. Published by Elsevier B.V.

Combining multi-pulse excitation and chirp coding in contrast-enhanced ultrasound imaging

International Nuclear Information System (INIS)

Crocco, M; Sciallero, C; Trucco, A; Pellegretti, P

2009-01-01

The development of techniques to separate the response of the contrast agent from that of the biological tissues is of great importance in ultrasound medical imaging. In the literature, one can find various solutions involving the use of multiple transmitted signals and the weighted sum of related echoes. In this paper, the combination of one of these multi-pulse techniques with a coded excitation is proposed and assessed. Coded excitation has been used mainly to increase the signal-to-noise ratio (SNR) and the penetration depth, provided that a matched filtering is applied in the reception chain. However, it has been shown that a signal with a long duration time also increases the backscattered echoes produced by the microbubbles and, consequently, the contrast-to-tissue ratio. Therefore, the implementation of a multi-pulse technique using a long coded pulse can yield a better contrast-to-tissue ratio and SNR. This paper investigates the combination of the linear chirp pulse with a multi-pulse technique based on the transmission of three pulses. The performance was evaluated using both simulated and real signals, assessing the improvement in the contrast-to-tissue ratio and SNR, the visual quality of the images obtained and the axial accuracy. A comparison with the same multi-pulse technique implemented using a traditional amplitude-modulated pulse revealed that the deployment of a chirp pulse produces several noticeable advantages and only a minor drawback

[Multi-channel cochlear implants in patients with Mondini malformation].

Science.gov (United States)

Li, Yong-xin; Han, De-min; Zhao, Xiao-tian; Chen, Xue-qing; Kong, Ying; Zheng, Jun; Liu, Bo; Liu, Sha; Mo, Ling-yan; Zhang, Hua; Wang, Shuo

2004-02-01

To describe clinical experiences with multi-channel cochlear implantation in patients with Mondini malformation. Among 300 patients who received multi-channel cochlear implants from 1996 to 2002 in Beijing Tongren Hospital, 15 patients were diagnosed with Mondini malformation. A retrospective analysis was performed dealing with the surgical techniques, mapping and rehabilitations characteristics after surgery. 15 patients with normal cochlear structure are consider as control group. Gusher is found more common than the normal cochlear implantation, most of them are serious. The electrodes are inserted in the "cochleostomy" in full length of 13 Patients, 2 pairs of electrodes remains outside of "cochleostomy" in 2 patients. No serious complications occurred after implantation. All patients have auditory sensations. The impedance of the electrodes, the T level, C level and the hearing threshold are similar with the normal cochlear implantation group. The results have no significant difference in compare with normal cochlear group(P > 0.05). Multi-channel cochlear implantation could be performed safely in patients with Mondini malformation. The primary outcome for patients with Mondini malformation are similar to those with normal cochlear structure following the multi-channel cochlear implantation.

Nine-channel mid-power bipolar pulse generator based on a field programmable gate array

Energy Technology Data Exchange (ETDEWEB)

Haylock, Ben, E-mail: benjamin.haylock2@griffithuni.edu.au; Lenzini, Francesco; Kasture, Sachin; Fisher, Paul; Lobino, Mirko [Centre for Quantum Dynamics, Griffith University, Brisbane (Australia); Queensland Micro and Nanotechnology Centre, Griffith University, Brisbane (Australia); Streed, Erik W. [Centre for Quantum Dynamics, Griffith University, Brisbane (Australia); Institute for Glycomics, Griffith University, Gold Coast (Australia)

2016-05-15

Many channel arbitrary pulse sequence generation is required for the electro-optic reconfiguration of optical waveguide networks in Lithium Niobate. Here we describe a scalable solution to the requirement for mid-power bipolar parallel outputs, based on pulse patterns generated by an externally clocked field programmable gate array. Positive and negative pulses can be generated at repetition rates up to 80 MHz with pulse width adjustable in increments of 1.6 ns across nine independent outputs. Each channel can provide 1.5 W of RF power and can be synchronised with the operation of other components in an optical network such as light sources and detectors through an external clock with adjustable delay.

Multi-channel distributed coordinated function over single radio in wireless sensor networks.

Science.gov (United States)

Campbell, Carlene E-A; Loo, Kok-Keong Jonathan; Gemikonakli, Orhan; Khan, Shafiullah; Singh, Dhananjay

2011-01-01

Multi-channel assignments are becoming the solution of choice to improve performance in single radio for wireless networks. Multi-channel allows wireless networks to assign different channels to different nodes in real-time transmission. In this paper, we propose a new approach, Multi-channel Distributed Coordinated Function (MC-DCF) which takes advantage of multi-channel assignment. The backoff algorithm of the IEEE 802.11 distributed coordination function (DCF) was modified to invoke channel switching, based on threshold criteria in order to improve the overall throughput for wireless sensor networks (WSNs) over 802.11 networks. We presented simulation experiments in order to investigate the characteristics of multi-channel communication in wireless sensor networks using an NS2 platform. Nodes only use a single radio and perform channel switching only after specified threshold is reached. Single radio can only work on one channel at any given time. All nodes initiate constant bit rate streams towards the receiving nodes. In this work, we studied the impact of non-overlapping channels in the 2.4 frequency band on: constant bit rate (CBR) streams, node density, source nodes sending data directly to sink and signal strength by varying distances between the sensor nodes and operating frequencies of the radios with different data rates. We showed that multi-channel enhancement using our proposed algorithm provides significant improvement in terms of throughput, packet delivery ratio and delay. This technique can be considered for WSNs future use in 802.11 networks especially when the IEEE 802.11n becomes popular thereby may prevent the 802.15.4 network from operating effectively in the 2.4 GHz frequency band.

MIMO wireless networks channels, techniques and standards for multi-antenna, multi-user and multi-cell systems

CERN Document Server

Clerckx, Bruno

2013-01-01

This book is unique in presenting channels, techniques and standards for the next generation of MIMO wireless networks. Through a unified framework, it emphasizes how propagation mechanisms impact the system performance under realistic power constraints. Combining a solid mathematical analysis with a physical and intuitive approach to space-time signal processing, the book progressively derives innovative designs for space-time coding and precoding as well as multi-user and multi-cell techniques, taking into consideration that MIMO channels are often far from ideal. Reflecting developments

Range based power control for multi-radio multi-channel wireless mesh networks

CSIR Research Space (South Africa)

Olwal, TO

2009-08-01

Full Text Available Multi-Radio Multi-Channel (MRMC) systems are key to power control problems in Wireless Mesh Networks (WMNs). In this paper, researchers present a range based dynamic power control for MRMC WMNs. First, WMN is represented as a set of disjoint Unified...

Profile correction to electron temperature and enhancement factor in soft-x-ray pulse-height-analysis measurements in tokamaks

International Nuclear Information System (INIS)

Sesnic, S.; Diesso, M.; Hill, K.; Holland, A.; Pohl, F.

1988-01-01

Because soft-x-ray pulse-height-analysis spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. The correction factors for the electron temperature and the enhancement factor as a function of the temperature and density profile parameters and the energy are obtained. The spectrum distortion due to pulse pileup effects is also evaluated. A set of curves is given from which the distortion of the spectrum can be obtained if the electron temperature, the Be filter thickness, and the electronic parameters of the acquisition system are known. PG 1810,1812 ID 131801CON N X-ray diagnostics TT Profile correction to electron temperature and enhancement factor in soft-x-ray pulse-height-analysis measurements in tokamaks AU S. Sesnic, M. Diesso, K. Hill, and A. Holland LO Princeton University, Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 AU F. Pohl LO Max-Planck Institut fuer Plasmaphysik, 8046-Garching, Federal Republic of Germany SD (Presented on 16 March 1988) AB Because soft-x-ray pulse-height-analysis spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. The correction factors for the electron temperature and the enhancement factor as a function of the temperature and density profile parameters and the energy are obtained. The spectrum distortion due to pulse pileup effects is also evaluated. A set of curves is given from which the distortion of the spectrum can be obtained if the electron tempe

The conversion of a pulse height analyzer to a time analyzer

International Nuclear Information System (INIS)

Adib, M.; Salama, M.; Abdel-Kawy, A.; Faragalla, S.; Sayed, E.M.; Hamouda, I.

1975-01-01

A transistorized time unit circuit has been designed to convert a 400-channel amplitude analyser (RIDL model 34-12B) to a 400 channel time analyser. The obtained time analyser has channel widths of 24.4 μs, 48.8 μs, 97.6 μs. Experimental determination of the stability of the obtained time analyser was carried out by measuring statistically distributed pulses at constant rate. The stability of the time analyser for long time operation was found to be not less than 0.14%. The linearity of the time scale calibration was checked by measuring the transmission of neutrons through a polycrystalline powder of nickel. This method was found to give a more precise calibration of the time scale than the method based on using the transmission of the elements with well known resonances. From the experimental values obtained for Bragg's cut-off positions for nickel, the non linearity was calculated and found not to exceed 0.3%

Use of trapezoidal shaping algorithm in the digital multi-channel system

International Nuclear Information System (INIS)

Wang Jihong; Wang Lianghou; Fang Zongliang

2011-01-01

It discusses one kind of digital filter technology-trapezoidal algorithm based on actual need of studying the digital multi-channel. Firstly, demonstrating the feasibility of the arithmetic with theoretical analysis; secondly, predigesting the process of the arithmetic; thirdly, simulating with MATLAB; lastly, using the arithmetic to measure data. The result of testing indicates trapezoidal shaping algorithm accords with the need of digital multi-channel shaping extraordinary. The best filter can be obtained by means of setting parameter due to superiority of digital multi-channel. (authors)

Allowable propagation of short pulse laser beam in a plasma channel and electromagnetic solitary waves

International Nuclear Information System (INIS)

Zhang, Shan; Hong, Xue-Ren; Wang, Hong-Yu; Xie, Bai-Song

2011-01-01

Nonparaxial and nonlinear propagation of a short intense laser beam in a parabolic plasma channel is analyzed by means of the variational method and nonlinear dynamics. The beam propagation properties are classified by five kinds of behaviors. In particularly, the electromagnetic solitary wave for finite pulse laser is found beside the other four propagation cases including beam periodically oscillating with defocussing and focusing amplitude, constant spot size, beam catastrophic focusing. It is also found that the laser pulse can be allowed to propagate in the plasma channel only when a certain relation for laser parameters and plasma channel parameters is satisfied. For the solitary wave, it may provide an effective way to obtain ultra-short laser pulse.

Soft error rate analysis methodology of multi-Pulse-single-event transients

International Nuclear Information System (INIS)

Zhou Bin; Huo Mingxue; Xiao Liyi

2012-01-01

As transistor feature size scales down, soft errors in combinational logic because of high-energy particle radiation is gaining more and more concerns. In this paper, a combinational logic soft error analysis methodology considering multi-pulse-single-event transients (MPSETs) and re-convergence with multi transient pulses is proposed. In the proposed approach, the voltage pulse produced at the standard cell output is approximated by a triangle waveform, and characterized by three parameters: pulse width, the transition time of the first edge, and the transition time of the second edge. As for the pulse with the amplitude being smaller than the supply voltage, the edge extension technique is proposed. Moreover, an efficient electrical masking model comprehensively considering transition time, delay, width and amplitude is proposed, and an approach using the transition times of two edges and pulse width to compute the amplitude of pulse is proposed. Finally, our proposed firstly-independently-propagating-secondly-mutually-interacting (FIP-SMI) is used to deal with more practical re-convergence gate with multi transient pulses. As for MPSETs, a random generation model of MPSETs is exploratively proposed. Compared to the estimates obtained using circuit level simulations by HSpice, our proposed soft error rate analysis algorithm has 10% errors in SER estimation with speed up of 300 when the single-pulse-single-event transient (SPSET) is considered. We have also demonstrated the runtime and SER decrease with the increment of P0 using designs from the ISCAS-85 benchmarks. (authors)

A cement channel-detection technique using the pulsed-neutron log

International Nuclear Information System (INIS)

Myers, G.D.

1991-01-01

A channel-detection technique has been developed using boron solutions and pulsed-neutron logging (PNL) tools. This technique relies on the extremely high-neutron-absorption cross section that boron exhibits relative to other common elements, including chlorine. The PNL tool is used to detect movement of a boron solution in a log-inject-log procedure. The technique has identified channels in such difficult applications as logging through two strings of pipe and in highly deviated wellbores. Logging procedures are simple and cement channels can be readily identified. The boron solutions are relatively inexpensive, safe to handle, and nonradioactive. Additional PNL information for reservoir performance evaluation is collected simultaneously during channel-detection logging. This paper describes the theory, development, field application, and limitations of this channel-detection logging technique

Experimental researches and comparison on aerodynamic parameters and cleaning efficiency of multi-level multi-channel cyclone

Directory of Open Access Journals (Sweden)

Aleksandras Chlebnikovas

2015-10-01

Full Text Available Multi-level multi-channel cyclone – the lately designed air cleaning device that can remove ultra-fine 20 μm particulatematter (PM from dusted air and reach over 95% of the overall cleaning efficiency. Multi-channel cyclone technology is based on centrifugal forces and has the resulting additional filtering process operation. Multi-level structure of cyclone allows to achieve higher air flow cleaning capacity at the same dimensions of the device, thus saving installation space required for the job, production and operating costs. Studies have examined the air flow parameters change in one–, two– and three–levels multichannel cyclone. These constructions differ according to the productivity of cleaned air under the constant peripheral and transitional (50/50 case air flow relations. Accordance with the results of air flow dynamics – velocity distribution of multi-channel cyclone, aerodynamic resistance and efficiency can be judged on the flow turbulence, the flow channel cross-section and select the most appropriate application. Cleaning efficiency studies were carried out using fine granite and wood ashes PM. The maximum cleaning efficiency was 93.3%, at an average of 4.5 g/m3, the aerodynamic resistance was equal to 1525 Pa.

Space Vector Pulse Width Modulation of a Multi-Level Diode ...

African Journals Online (AJOL)

Space Vector Pulse Width Modulation of a Multi-Level Diode Clamped ... of MATLAB /SIMULINK modeling of the space vector pulse-width modulation and the ... two adjacent active vectors in determining the switching process of the multilevel ...

Femtosecond laser direct generation of 3D-microfluidic channels inside bulk PMMA.

Science.gov (United States)

Roth, Gian-Luca; Esen, Cemal; Hellmann, Ralf

2017-07-24

We report on laser direct generation of 3D-microchannels for microfluidic applications inside PMMA bulk material by focused femtosecond pulses. Inner lying channels with cross sectional areas from 100 µm 2 to 4400 µm 2 are directly created in the volume of a PMMA substrate. Using the presented process, the channel length is fundamentally unlimited. Here we demonstrate a channel length of 6 meters inside a substrate with dimensions of 20 × 20 × 1.1 mm. The formation of the micro channels is based on nonlinear absorption around the focal volume that triggers a material modification. The modified volume can be selectively opened to form the channel by a subsequent annealing process. The cross section of the channel is strongly influenced by the energy distribution and illumination around the focal volume determined by the optical setup and process design. The 3D channel layout can easily be realized by moving the specimen using 3D motorized stage, allowing freely chosen complex shaped channel architectures. Within a comprehensive parameter study, varying laser power, number of multi-passes, writing speed and writing depths, we identify an optimized process in terms of attainable channel height, width and aspect ratio, as well as process stability and reproducibility. The proof of concept for an application in three dimensional microfluidic systems is provided by florescence microscopy using a dye rhodamine B solution in isopropanol.

Multi-channel normal speed gated integrator in the measurement of the laser scattering light energy

International Nuclear Information System (INIS)

Yang Dong; Yu Xiaoqi; Hu Yuanfeng

2005-01-01

With the method of integration in a limited time, a Multi-channel normal speed gated integrator based on VXI system has been developed for measuring the signals with changeable pulse width in laser scattering light experiment. It has been tested with signal sources in ICF experiment. In tests, the integral nonlinearity between the integral results of the gated integrator and that of an oscilloscope is less than 1%. In the ICF experiments the maximum error between the integral results of the gated integrator and that of oscilloscope is less than 3% of the full scale range of the gated integrator. (authors)

Nonlinear Theory of Nonparaxial Laser Pulse Propagation in Plasma Channels

International Nuclear Information System (INIS)

Esarey, E.; Schroeder, C. B.; Shadwick, B. A.; Wurtele, J. S.; Leemans, W. P.

2000-01-01

Nonparaxial propagation of ultrashort, high-power laser pulses in plasma channels is examined. In the adiabatic limit, pulse energy conservation, nonlinear group velocity, damped betatron oscillations, self-steepening, self-phase modulation, and shock formation are analyzed. In the nonadiabatic limit, the coupling of forward Raman scattering (FRS) and the self-modulation instability (SMI) is analyzed and growth rates are derived, including regimes of reduced growth. The SMI is found to dominate FRS in most regimes of interest. (c) 2000 The American Physical Society

Multiple-state based power control for multi-radio multi-channel wireless mesh networks

CSIR Research Space (South Africa)

Olwal, TO

2009-01-01

Full Text Available Multi-Radio Multi-Channel (MRMC) systems are key to power control problems in wireless mesh networks (WMNs). In this paper, we present asynchronous multiple-state based power control for MRMC WMNs. First, WMN is represented as a set of disjoint...

Empirical Study on Multi-Channel Service Quality and Customer Loyalty of Retailers

OpenAIRE

Qi Yong-zhi

2014-01-01

This paper studies the influence of offline RSSQ (retailing store service quality), online store ESQ (E-service quality) and O2O MCISQ (multi-channel integration service quality) on traditional retailers' customer loyalty as well as the relation of them three in multi-channel retailing. 380 customers with both offline and online shopping experience at the same retailer's store are investigated. Through the structural equation model, we find out that in multi-channel retailing, RSSQ and MCISQ ...

Multi-channel motor evoked potential monitoring during anterior cervical discectomy and fusion

Directory of Open Access Journals (Sweden)

Dong-Gun Kim

Full Text Available Objectives: Anterior cervical discectomy and fusion (ACDF surgery is the most common surgical procedure for the cervical spine with low complication rate. Despite the potential prognostic benefit, intraoperative neurophysiological monitoring (IONM, a method for detecting impending neurological compromise, is not routinely used in ACDF surgery. The present study aimed to identify the potential benefits of monitoring multi-channel motor evoked potentials (MEPs during ACDF surgery. Methods: We retrospectively reviewed 200 consecutive patients who received IONM with multi-channel MEPs and somatosensory evoked potentials (SSEPs. On average, 9.2 muscles per patient were evaluated under MEP monitoring. Results: The rate of MEP change during surgery in the multi-level ACDF group was significantly higher than the single-level group. Two patients from the single-level ACDF group (1.7% and four patients from the multi-level ACDF group (4.9% experienced post-operative motor deficits. Multi-channel MEPs monitoring during single and multi-level ACDF surgery demonstrated higher sensitivity, specificity, positive predictive and negative predictive value than SSEP monitoring. Conclusions: Multi-channel MEP monitoring might be beneficial for the detection of segmental injury as well as long tract injury during single- and multi-level ACDF surgery. Significance: This is first large scale study to identify the usefulness of multi-channel MEPs in monitoring ACDF surgery. Keywords: Disc disease, Somatosensory evoked potentials, Intraoperative neurophysiological monitoring, Motor evoked potentials, Anterior cervical discectomy and fusion

Design criteria for pulse transformers used in neutron detector pulse counting channels

International Nuclear Information System (INIS)

Powler, E.P.

1963-10-01

The need for long cables between the detector and head amplifier in neutron pulse counting channels has led to the development of systems in which a transformer is used to 'match' the high impedance of a fission or proportional counter to the characteristic impedance of the cable. A further transformer can be used to match the cable to the input of a low noise pulse amplifier if this has a high impedance. This report is intended to give the designer sufficient information to optimise a system and predict the performance in terms of signal to noise ratio, resolving time and gain. Related problems are covered and include the use of balanced twin cables, the requirements of temperatures up to 500 deg. C and the need for high interference rejection. Two systems are described in some detail to emphasise the principles of design. (author)

Pulse height defect in ion implanted silicon detector for heavy ions with Z=6-28 in the energy range ∼ 0.25-2.5 MeV/u

International Nuclear Information System (INIS)

Diwan, P.K.; Sharma, V.; Shyam Kumar; Avasthi, D.K.

2005-01-01

The response of ion implanted silicon detector has been studied for heavy ions with Z= 6-28 in the energy range ∼ 0.25-2.5 MeV/u utilizing the 15UD Pelletron Accelerator facility at Nuclear Science Centre, New Delhi, India. The variation of pulse height in ion implanted silicon detector with projectile's atomic number and its energy have been investigated. It has been observed that pulse height-energy calibration for a given projectile is described well by a linear relationship indicating no pulse height defect with the variation in energy for specific Z projectile. Pulse height defect has been found to increase with increasing projectile atomic number. The mean slope of the collected charge signal versus projectile energy depends significantly on the atomic number of the projectile. (author)

Dynamics of laser-induced channel formation in water and influence of pulse duration on the ablation of biotissue under water with pulsed erbium-laser radiation

Science.gov (United States)

Ith, M.; Pratisto, H.; Altermatt, H. J.; Frenz, M.; Weber, H. P.

1994-12-01

The ability to use fiber-delivered erbium-laser radiation for non-contact arthroscopic meniscectomy in a liquid environment was studied. The laser radiation is transmitted through a water-vapor channel created by the leading part of the laser pulse. The dynamics of the channel formation around a submerged fiber tip was investigated with time-resolved flash photography. Strong pressure transients with amplitudes up to a few hundreds of bars measured with a needle hydrophone were found to accompany the channel formation process. Additional pressure transients in the range of kbars were observed after the laser pulse associated with the collapse of the vapor channel. Transmission measurements revealed that the duration the laser-induced channel stays open, and therefore the energy transmittable through it, is substantially determined by the laser pulse duration. The optimum pulse duration was found to be in the range between 250 and 350 µS. This was confirmed by histological evaluations of the laser incisions in meniscus: Increasing the pulse duration from 300 to 800 µs leads to a decrease in the crater depth from 1600 to 300 µm. A comparison of the histological examination after laser treatment through air and through water gave information on the influence of the vapor channel on the ablation efficiency, the cutting quality and the induced thermal damage in the adjacent tissue. The study shows that the erbium laser combined with an adequate fiber delivery system represents an effective surgical instrument liable to become increasingly accepted in orthopedic surgery.

An improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum

International Nuclear Information System (INIS)

Zhang, Jinping; Chen, Yuping; Hu, Mengning; Chen, Xianfeng

2015-01-01

In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes

An improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jinping; Chen, Yuping, E-mail: ypchen@sjtu.edu.cn; Hu, Mengning; Chen, Xianfeng [State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

2015-02-14

In this paper, an improved three-dimensional two-temperature model for multi-pulse femtosecond laser ablation of aluminum was proposed and proved in our experiment. Aiming to achieve hole-drilling with a high ratio of depth/entrance diameter in vacuum, this model can predict the depth and radius of the drilled holes precisely when employing different laser parameters. Additionally, for multi-pulse laser ablation, we found that the laser fluence and number of pulses are the dominant parameters and the multi-pulse ablation threshold is much lower than the single-pulse one, which will help to obtain high-quality holes.

Energy reduction using multi-channels optical wireless communication based OFDM

Science.gov (United States)

Darwesh, Laialy; Arnon, Shlomi

2017-10-01

In recent years, an increasing number of data center networks (DCNs) have been built to provide various cloud applications. Major challenges in the design of next generation DC networks include reduction of the energy consumption, high flexibility and scalability, high data rates, minimum latency and high cyber security. Use of optical wireless communication (OWC) to augment the DC network could help to confront some of these challenges. In this paper we present an OWC multi channels communication method that could lead to significant energy reduction of the communication equipment. The method is to convert a high speed serial data stream to many slower and parallel streams and vies versa at the receiver. We implement this concept of multi channels using optical orthogonal frequency division multiplexing (O-OFDM) method. In our scheme, we use asymmetrically clipped optical OFDM (ACO-OFDM). Our results show that the realization of multi channels OFDM (ACO-OFDM) methods reduces the total energy consumption exponentially, as the number of channels transmitted through them rises.

A multi-channel humidity control system based on LabVIEW

International Nuclear Information System (INIS)

Zhang Aiwu; Xie Yuguang; Liu Hongbang; Liu Yingbiao; Cai Xiao; Yu Boxiang; Lu Junguang; Zhou Li

2011-01-01

A real time multi-channel humidity control system was designed based on LabVIEW, using the dry air branch of BESⅢ drying system. The hardware of this control system consist of mini humidity and temperature sensors, intelligent collection module, switch quantity controller and electromagnetic valves. The humidity can be controlled at arbitrary value from air humidity to 3% with accuracy better than 2%. Multi microenvironment with different humidity can be easily controlled and monitored in real time by this system. It can also be extended to hybrid control of multi channel humidity and temperature. (authors)

MICROCALORIMETER SPECTROSCOPY AT HIGH PULSE RATES: A MULTI-PULSE FITTING TECHNIQUE

Energy Technology Data Exchange (ETDEWEB)

Fowler, J. W.; Alpert, B. K.; Doriese, W. B.; Joe, Y. I.; O’Neil, G. C.; Swetz, D. S.; Ullom, J. N. [National Institute of Standards and Technology, 325 Broadway MS 686.02, Boulder, CO 80305 (United States); Fischer, D. A.; Jaye, C. [National Institute of Standards and Technology, Brookhaven National Lab, Brookhaven, NY (United States)

2015-08-15

Transition Edge Sensor microcalorimeters can measure X-ray and gamma-ray energies with very high energy resolution and high photon-collection efficiency. For this technology to reach its full potential in future X-ray observatories, each sensor must be able to measure hundreds or even thousands of photon energies per second. Current “optimal filtering” approaches to achieve the best possible energy resolution work only for photons that are well isolated in time, a requirement which is in direct conflict with the need for high-rate measurements. We describe a new analysis procedure to allow fitting for the pulse height of all photons even in the presence of heavy pulse pile-up. In the limit of isolated pulses, the technique reduces to standard optimal filtering with long records. We employ reasonable approximations to the noise covariance function in order to render this procedure computationally viable even for very long data records. The technique is employed to analyze X-ray emission spectra at 600 eV and 6 keV at rates up to 250 counts s{sup −1} in microcalorimeters having exponential signal decay times of approximately 1.2 ms.

Simulation study on vertically distributed multi-channel tangential interferometry for KSTAR

International Nuclear Information System (INIS)

Nam, Y U; Juhn, J W

2012-01-01

Interferometry is powerful and reliable diagnostics which measures line-integrated electron density. Since this technique only measures an averaged value over whole probing line, a multi-channel scheme is used for an analysis for spatial distribution and variation of electron density. Typical setups of the multi-channel measurement are schemes of radially distributed vertical lines, vertically distributed horizontal lines and horizontally distributed tangential lines. In Korea Superconducting Tokamak Advanced Research, a vertically distributed multi-channel tangential interferometry is planned instead of above typical schemes due to limitation of complex in-vessel geometry and narrow diagnostics port through cryostat. Total 5-channels will be vertically placed as symmetric with the mid-plain. One of the characteristic features of the vertically distributed channels is that each channel is viewing different poloidal angle, while the horizontally distributed channels are viewing different toroidal angle. This scheme also can be used on an investigation of the up-down asymmetry and the vertical oscillation of plasma. Simulation has been performed and the result will be discussed to verify the possibility and the estimated effectiveness of the scheme on this paper.

Application-oriented research on plasma channeling of a large pulsed current

International Nuclear Information System (INIS)

Liu Jingye

2000-01-01

Utilizing the avalanche effect of plasma produced by the collision of energetic primary electrons with hydrogen molecules in a plasma, channeling of a large pulsed current is achieved, with the plasma acting as the carrier

Control programs of multichannel pulse height analyzer with CAMAC system using FACOM U-200 mini-computer

International Nuclear Information System (INIS)

Yamagishi, Kojiro

1978-02-01

The 4096 channel Pulse Height Analyzer (PHA) assembled with CAMAC plug-in units has been developed in JAERI. The PHA consists of ADC unit, CRT-display unit, and CAMAC plug-in units, which are memory-controller, MCA-timer, 4K words RAM memory and CRT-driver. The system is on-line connected to FACOM U-200 Mini-Computer through CAMAC interface unit Crate-controller. The softwares for on-line data acquisition of the system have been developed. These are four utility programs written in FORTRAN and two program packages written in assembler language FASP which are CAMAC Program Package and Basic Input/Output Program Package. CAMAC Program Package has 18 subroutine programs for control of CAMAC plug-in units from FACOM U-200 Mini-Computer; and Basic Input/Output Program Package has 26 subroutine programs to input/output data to/from a typewriter, keyboard, cassette magnetic tape and open reel magnetic tape. These subroutine programs are all FORTRAN callable. The PHA with CAMAC system is first outlined, and then usage is described in detail of four utility programs, CAMAC Program Package and Basic Input/Output Program Package. (auth.)

Multi-pulse frequency shifted (MPFS) multiple access modulation for ultra wideband

Science.gov (United States)

Nekoogar, Faranak [San Ramon, CA; Dowla, Farid U [Castro Valley, CA

2012-01-24

The multi-pulse frequency shifted technique uses mutually orthogonal short duration pulses o transmit and receive information in a UWB multiuser communication system. The multiuser system uses the same pulse shape with different frequencies for the reference and data for each user. Different users have a different pulse shape (mutually orthogonal to each other) and different transmit and reference frequencies. At the receiver, the reference pulse is frequency shifted to match the data pulse and a correlation scheme followed by a hard decision block detects the data.

Multi-Channel Capacitive Sensor Arrays

Directory of Open Access Journals (Sweden)

Bingnan Wang

2016-01-01

Full Text Available In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved.

Multi-channel data acquisition and processing system for moessbauer spectroscopy

International Nuclear Information System (INIS)

Jin Ge; Yang Yanming

1987-01-01

A multi-channel data acquisition and processing system for moessbauer spectroscopy is described, which consists of an intelligent interface and a BC3-80 microcomputer. The system has eight data channels, each channel contains a counting circuit and a memory. A Z80-CPU is used as a main unit for control and access. The microcomputer is used for real-time displaying spectrum, saving the data to disk, printing data and data processing. The system is applicable to a high counting rate multi-wire proportional chamber. It can increase greatly the counting rate for measuring moessbauer spectrum. The signals of each wire in the chamber go through a corresponding amplifier and a differential discriminator and are recorded by a corresponding data channel, the data of each channel is added by the microcomputer. In addition, two channels can be used to measure an absorption and a scattering spectrum at the same time and the internal and the surface information of the sample are obtained simultaneously

Automatically sweeping dual-channel boxcar integrator

International Nuclear Information System (INIS)

Keefe, D.J.; Patterson, D.R.

1978-01-01

An automatically sweeping dual-channel boxcar integrator has been developed to automate the search for a signal that repeatedly follows a trigger pulse by a constant or slowly varying time delay when that signal is completely hidden in random electrical noise and dc-offset drifts. The automatically sweeping dual-channel boxcar integrator improves the signal-to-noise ratio and eliminates dc-drift errors in the same way that a conventional dual-channel boxcar integrator does, but, in addition, automatically locates the hidden signal. When the signal is found, its time delay is displayed with 100-ns resolution, and its peak value is automatically measured and displayed. This relieves the operator of the tedious, time-consuming, and error-prone search for the signal whenever the time delay changes. The automatically sweeping boxcar integrator can also be used as a conventional dual-channel boxcar integrator. In either mode, it can repeatedly integrate a signal up to 990 times and thus make accurate measurements of the signal pulse height in the presence of random noise, dc offsets, and unsynchronized interfering signals

Dual-Pulse Pulse Position Modulation (DPPM) for Deep-Space Optical Communications: Performance and Practicality Analysis

Science.gov (United States)

Li, Jing; Hylton, Alan; Budinger, James; Nappier, Jennifer; Downey, Joseph; Raible, Daniel

2012-01-01

Due to its simplicity and robustness against wavefront distortion, pulse position modulation (PPM) with photon counting detector has been seriously considered for long-haul optical wireless systems. This paper evaluates the dual-pulse case and compares it with the conventional single-pulse case. Analytical expressions for symbol error rate and bit error rate are first derived and numerically evaluated, for the strong, negative-exponential turbulent atmosphere; and bandwidth efficiency and throughput are subsequently assessed. It is shown that, under a set of practical constraints including pulse width and pulse repetition frequency (PRF), dual-pulse PPM enables a better channel utilization and hence a higher throughput than it single-pulse counterpart. This result is new and different from the previous idealistic studies that showed multi-pulse PPM provided no essential information-theoretic gains than single-pulse PPM.

Multi-Gaussian fitting for pulse waveform using Weighted Least Squares and multi-criteria decision making method.

Science.gov (United States)

Wang, Lu; Xu, Lisheng; Feng, Shuting; Meng, Max Q-H; Wang, Kuanquan

2013-11-01

Analysis of pulse waveform is a low cost, non-invasive method for obtaining vital information related to the conditions of the cardiovascular system. In recent years, different Pulse Decomposition Analysis (PDA) methods have been applied to disclose the pathological mechanisms of the pulse waveform. All these methods decompose single-period pulse waveform into a constant number (such as 3, 4 or 5) of individual waves. Furthermore, those methods do not pay much attention to the estimation error of the key points in the pulse waveform. The estimation of human vascular conditions depends on the key points' positions of pulse wave. In this paper, we propose a Multi-Gaussian (MG) model to fit real pulse waveforms using an adaptive number (4 or 5 in our study) of Gaussian waves. The unknown parameters in the MG model are estimated by the Weighted Least Squares (WLS) method and the optimized weight values corresponding to different sampling points are selected by using the Multi-Criteria Decision Making (MCDM) method. Performance of the MG model and the WLS method has been evaluated by fitting 150 real pulse waveforms of five different types. The resulting Normalized Root Mean Square Error (NRMSE) was less than 2.0% and the estimation accuracy for the key points was satisfactory, demonstrating that our proposed method is effective in compressing, synthesizing and analyzing pulse waveforms. Copyright © 2013 Elsevier Ltd. All rights reserved.

The molecular mechanism of multi-ion conduction in K{sup +} channels

Energy Technology Data Exchange (ETDEWEB)

Gwan, J.F.

2007-01-19

Steered molecular dynamics (SMD) simulation method is applied to a fully solvated membrane-channel model for studying the ion permeation process in potassium channels. The channel model is based on the crystallographic structure of a prokaryotic K{sup +} channel- the KcsA channel, which is a representative of most known eukaryotic K{sup +} channels. It has long been proposed that the ion transportation in a conventional K{sup +}-channel follows a multi-ion fashion: permeating ions line in a queue in the channel pore and move in a single file through the channel. The conventional view of multi-ion transportation is that the electrostatic repulsion between ions helps to overcome the attraction between ions and the channel pore. In this study, we proposed two SMD simulation schemes, referred to 'the single-ion SMD' simulations and 'the multi-ion SMD' simulations. Concerted movements of a K-W-K sequence in the selectivity filter were observed in the single-ion SMD simulations. The analysis of the concerted movement reveals the molecular mechanism of the multi-ion transportation. It shows that, rather than the long range electrostatic interaction, the short range polar interaction is a more dominant factor in the multi-ion transportation. The polar groups which play a role in the concerted transportation are the water molecules and the backbone carbonyl groups of the selectivity filter. The polar interaction is sensitive to the relative orientation of the polar groups. By changing the orientation of a polar group, the interaction may switch from attractive to repulsive or vice versa. By this means, the energy barrier between binding sites in the selectivity filter can be switched on and off, and therefore the K{sup +} may be able to move to the neighboring binding site without an external driving force. The concerted transportation in the selectivity filter requires a delicate cooperation between K{sup +}, waters, and the backbone carbonyl groups. To

Design of Robust Pulses to Insufficient Synchronization for OFDM/OQAM Systems in Doubly Dispersive Channels

Directory of Open Access Journals (Sweden)

Yu Zhao

2015-01-01

Full Text Available This paper presents a pulse shaping method robust to insufficient synchronization in orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM/OQAM systems over doubly dispersive (DD channels. The proposed pulse is designed as a linear combination of several well localized Hermite functions. The coefficients optimization problem is modeled as a nonconvex constrained fractional programming problem based on the signal-to-interference ratio (SIR maximization criterion. An efficient iterative algorithm is applied to simplify the problem to a series of quadratically constrained quadratic program (QCQP problems which can be solved by semidefinite relaxation (SDR method. Simulation results show that the proposed pulse is superior to traditional pulses with respect to SIR performance over DD channels in the presence of carrier frequency offset (CFO and timing offset (TO.

Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

International Nuclear Information System (INIS)

Xia Liansheng; Yang Anmin; Chen Yi; Zhang Huang; Liu Xingguang; Li Jin; Jiang Xiaoguo; Zhang Kaizhi; Shi Jinshui; Deng Jianjun; Zhang Linwen

2010-01-01

The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process. (authors)

Performance evaluation of CPPM modulation in multi-path environments

International Nuclear Information System (INIS)

Tasev, Zarko; Kocarev, Ljupco

2003-01-01

Chaotic pulse position modulation (CPPM) is a novel technique to communicate with chaotic signals based upon pulse trains in which the intervals between two pulses are determined by chaotic dynamics of a pulse generator. Using numerical simulations we show that CPPM offers excellent multi-path performance. We simulated the CPPM radio system, which is designed for a WLAN application and operates in the 2.4 GHz ISM frequency band with IEEE 802.11 compliant channel spacing. In this case, the average performance loss due the multi-path for CPPM is less than 5 dB

Performance evaluation of CPPM modulation in multi-path environments

Energy Technology Data Exchange (ETDEWEB)

Tasev, Zarko E-mail: ztasev@ucsd.edu; Kocarev, Ljupco E-mail: lkocarev@ucsd.edu

2003-01-01

Chaotic pulse position modulation (CPPM) is a novel technique to communicate with chaotic signals based upon pulse trains in which the intervals between two pulses are determined by chaotic dynamics of a pulse generator. Using numerical simulations we show that CPPM offers excellent multi-path performance. We simulated the CPPM radio system, which is designed for a WLAN application and operates in the 2.4 GHz ISM frequency band with IEEE 802.11 compliant channel spacing. In this case, the average performance loss due the multi-path for CPPM is less than 5 dB.

Exploiting Multi-user Diversity and Multi-hop Diversity in Dual-hop Broadcast Channels

KAUST Repository

Zafar, Ammar

2013-05-21

We propose joint user-and-hop scheduling over dual-hop block-fading broadcast channels in order to exploit multi-user diversity gains and multi-hop diversity gains all together. To achieve this objective, the first and second hops are scheduled opportunistically based on the channel state information. The joint scheduling problem is formulated as maximizing the weighted sum of the long term achievable rates of the users under a stability constraint, which means that in the long term the rate received by the relay should equal the rate transmitted by it, in addition to power constraints. We show that this problem is equivalent to a single-hop broadcast channel by treating the source as a virtual user with an optimal weight that maintains the stability constraint. We show how to obtain the source weight either off-line based on channel statistics or on real-time based on channel measurements. Furthermore, we consider special cases including the maximum sum-rate scheduler and the proportional fair scheduler. We also show how to extend the scheme into one that allows multiple user scheduling via superposition coding with successive decoding. Numerical results demonstrate that our proposed joint scheduling scheme enlarges the rate region as compared to scheduling schemes that exploit the diversity gains partially.

Fast Computation of Pulse Height Spectra Using SGRD Code

Directory of Open Access Journals (Sweden)

Humbert Philippe

2017-01-01

Full Text Available SGRD (Spectroscopy, Gamma rays, Rapid, Deterministic code is used for fast calculation of the gamma ray spectrum produced by a spherical shielded source and measured by a detector. The photon source lines originate from the radioactive decay of the unstable isotopes. The emission rate and spectrum of these primary sources are calculated using the DARWIN code. The leakage spectrum is separated in two parts, the uncollided component is transported by ray-tracing and the scattered component is calculated using a multigroup discrete ordinates method. The pulsed height spectrum is then simulated by folding the leakage spectrum with the detector response functions which are pre-calculated using MCNP5 code for each considered detector type. An application to the simulation of the gamma spectrum produced by a natural uranium ball coated with plexiglass and measured using a NaI detector is presented.

Progress on channel spark development and application of pulsed electron beam deposition (PED) in the field of medical coating work

International Nuclear Information System (INIS)

Schultheiss, Christoph; Buth, Lothar-H.-O.; Frey, Wolfgang; Bluhm, Hansjoachim; Mayer, Hanns-G.

2002-01-01

A promising source for Pulsed Electron Beam Deposition (PED) is the channel spark. Recent improvements helped to reduce beam instabilities which up to now have limited the life time of the system. The beam power could be increased and because of better beam quality the transport length of the beam is increased from 1 to several centimeters (up to 10 cm). Together with other improvements on the triggering system and beam transport in dielectric tubes, the channel spark approaches industrial standards. An overview of actual applications in research and industry will be presented. An attractive feature of the pulsed electron beam thin film deposition is the conservation of stoichiometry even during deposition of multi-component earth-alkali and alkali glasses. Specially developed glasses like BIOGLAS registered have the ability to anchor soft living tissue at the surface. In form of a bulk material bio active glasses are brittle limiting its applications. Contrary to brittle bulk material a thin layers on medical implants exhibits reliable bio-functionality. Coating of implants with this category of materials is subject of the European INCOMED project (Innovative Coating of Medical Implants with Soft Tissue Anchoring Ability) which just has started

Pulse shape analyzer/timing-SCA application to beta measurement

International Nuclear Information System (INIS)

Selvi, S.; Celiktas, C.

2001-01-01

Electrical noise contribution to pulse height distributions from beta sources due to BC-400 plastic scintillator(PS), preamplifier and spectroscopy amplifier was rejected by setting the electronic set-up processing of the modified beta spectrometer consisted of pulse shape analyzer/timing single channel analyzer (PSA/SCA) and related complementary equipments. Improved noise rejection performance was evaluated in terms of elimination practically only all of the noise band of C-14 and Tl-204 spectra obtained using the two alternate beta spectrometer

A multi-channel isolated power supply in non-equipotential circuit

Science.gov (United States)

Li, Xiang; Zhao, Bo-Wen; Zhang, Yan-Chi; Xie, Da

2018-04-01

A multi-channel isolation power supply is designed for the problems of different MOSFET or IGBT in the non-equipotential circuit in this paper. It mainly includes the square wave generation circuit, the high-frequency transformer and the three-terminal stabilized circuit. The first part is used to generate the 24V square wave, and as the input of the magnetic ring transformer. In the second part, the magnetic ring transformer consists of one input and three outputs to realize multi-channel isolation output. The third part can output different potential and realize non-equal potential function through the three-terminal stabilized chip. In addition, the multi-channel isolation power source proposed in this paper is Small size, high reliability and low price, and it is convenient for power electronic switches that operate on multiple different potentials. Therefore, the research on power supply of power electronic circuit has practical significance.

MASMA: a versatile multifunctional unit (gated window amplifier, analog memory, and height-to-time converter)

International Nuclear Information System (INIS)

Goursky, V.; Thenes, P.

1969-01-01

This multipurpose unit is designed to accomplish one of the following functions: - gated window amplifier, - Analog memory and - Amplitude-to-time converter. The first function is mainly devoted to improve the poor resolution of pulse-height analyzers with a small number of channels. The analog memory, a new function in the standard range of plug-in modules, is capable of performing a number of operations: 1) fixed delay, or variable delay dependent on an external parameter (application to the analog processing of non-coincident pulses), 2) de-randomiser to increase the efficiency of the pulse height analysis in a spectrometry experiment, 3) linear multiplexer to allow an analyser to serve as many spectrometry devices as memory elements that it possesses. Associated with a coding scaler, this unit, if used as a amplitude-to-time converter, constitutes a Wilkinson A.D.C with a capability of 10 bits (or more) and with a 100 MHz clock frequency. (authors) [fr

Exponential decay and exponential recovery of modal gains in high count rate channel electron multipliers

International Nuclear Information System (INIS)

Hahn, S.F.; Burch, J.L.

1980-01-01

A series of data on high count rate channel electron multipliers revealed an initial drop and subsequent recovery of gains in exponential fashion. The FWHM of the pulse height distribution at the initial stage of testing can be used as a good criterion for the selection of operating bias voltage of the channel electron multiplier

Effect of Channel Orientation and Rib Pitch-to-Height Ratio on Pressure Drop in a Rotating Square Channel with Ribs on Two Opposite Surfaces

Directory of Open Access Journals (Sweden)

Prabhu S. V.

2005-01-01

Full Text Available The effect of channel orientation and rib pitch-to-height ratio on the pressure drop distribution in a rib-roughened channel is an important issue in turbine blade cooling. The present investigation is a study of the overall pressure drop distribution in a square cross-sectioned channel, with rib turbulators, rotating about an axis normal to the free stream. The ribs are configured in a symmetric arrangement on two opposite surfaces with a rib angle of 90 ∘ to the mainstream flow. The study has been conducted for three Reynolds numbers, namely, 13 000, 17 000, and 22 000 with the rotation number varying from 0– 0.38 . Experiments have been carried out for various rib pitch-to-height ratios ( P/e with a constant rib height-to-hydraulic diameter ratio ( e/D of 0.1 . The test section in which the ribs are placed on the leading and trailing surfaces is considered as the base case ( orientation angle= 0 ∘ , Coriolis force vector normal to the ribbed surfaces. The channel is turned about its axis in steps of 15 ∘ to vary the orientation angle from 0 ∘ to 90 ∘ . The overall pressure drop does not change considerably under conditions of rotation for the base case. However, for the other cases tested, it is observed that the overall pressure drop increases with an increase in the rotation number for a given orientation angle and also increases with an increase in the orientation angle for a given rotation number. This change is attributed to the variation in the separation zone downstream of the ribs due to the presence of the Coriolis force—local pressure drop data is presented which supports this idea. At an orientation angle of 90 ∘ (ribs on the top and bottom surfaces, Coriolis force vector normal to the smooth surfaces, the overall pressure drop is observed to be maximum during rotation. The overall pressure drop for a case with a rib pitch-to-height ratio of 5 on both surfaces is found to be the highest

Metasurface for multi-channel terahertz beam splitters and polarization rotators

Science.gov (United States)

Zang, XiaoFei; Gong, HanHong; Li, Zhen; Xie, JingYa; Cheng, QingQing; Chen, Lin; Shkurinov, Alexander P.; Zhu, YiMing; Zhuang, SongLin

2018-04-01

Terahertz beam splitters and polarization rotators are two typical devices with wide applications ranging from terahertz communication to system integration. However, they are faced with severe challenges in manipulating THz waves in multiple channels, which is desirable for system integration and device miniaturization. Here, we propose a method to design ultra-thin multi-channel THz beam splitters and polarization rotators simultaneously. The reflected beams are divided into four beams with nearly the same density under illumination of linear-polarized THz waves, while the polarization of reflected beams in each channel is modulated with a rotation angle or invariable with respect to the incident THz waves, leading to the multi-channel polarization rotator (multiple polarization rotation in the reflective channels) and beam splitter, respectively. Reflective metasurfaces, created by patterning metal-rods with different orientations on a polyimide film, were fabricated and measured to demonstrate these characteristics. The proposed approach provides an efficient way of controlling polarization of THz waves in various channels, which significantly simplifies THz functional devices and the experimental system.

The effect of ratio between rigid plant height and water depth on the manning’s coefficient in open channel

Science.gov (United States)

Rizalihadi, M.; Ziana; Shaskia, Nina; Asharly, H.

2018-05-01

One of the important factors in channel dimension is the Manning’s coefficient ( n ). This coefficient is influenced not only by the channel roughness but also by the presence of plants in the channel. The aim of the study is to see the effect of the ratio between the height of the rigid plant and water depth on the Manning’s coefficient (n) in open channel. The study was conducted in open channel with 15.5 m long, 0.5 m wide and 1.0 m high, in which at the center of the channel is planted with the rigid plants with a density of 42 plants/m2. The flow was run with a discharge of 0.013 m3/s at 6 ratios of Hplants/Hwater, namely: 0; 0.2; 0.6; 0.8; 1,0 and 1,2, to obtain the velocity and water profiles. Then the value of n is analyzed using Manning’s equation. The results showed that the mean velocity becomes decrease 17.81-34.01% as increase the ratio of Hplants/Hwater. This results in increasing n value to become 1.22-1.52 times compared to the unplanted channel ( no =0.038). So, it can be concluded that the ratio between the rigid plant’s height and water depth in the open channel can affect the value of Manning coefficient.

Computer model for calculating gamma-ray pulse-height spectra for logging applications

International Nuclear Information System (INIS)

Evans, M.L.

1981-01-01

A generalized computer model has been devised to simulate the emission, transport, and detection of natural gamma radiation from various logging environments. The model yields high-resolution gamma-ray pulse-height spectra that can be used to correct both gross gamma and spectral gamma-ray logs. The technique can help provide corrections to airborne and surface radiometric survey logs for the effects of varying altitude, formation composition, and overburden. Applied to borehole logging, the model can yield estimates of the effects of varying borehole fluid and casing attenuations, as well as varying formation porosity and saturation

Data acquisition systems for uses of multi-counter time analyzer and one-dimensional PSD pulse height analyzer to neutron scattering measurements

International Nuclear Information System (INIS)

Ono, Masayoshi; Tasaki, Seiji; Okamoto, Sunao

1989-01-01

A data acquisition system having the various modern electronic devices was designed and tested for practical use of neutron time-of-flight (TOF) measurements with multiple counters. The system is principally composed of TOF logic units (load-able up to 128 units) with a control unit and a conventional micro-computer. The TOF logic unit (main memory, 2048 ch, 24 bits/ch) demonstrates about 1.7 times higher efficiency for neutron counting rate per channel than the one by a conventional TOF logic unit. Meanwhile, some data-access functions of the TOF logic unit were applied to position sensitive analyzer of one-dimensional neutron PSD for small angle scattering. The analyzer was tested with use of pulse generator. The result shows good linearity. (author)

Plasma channels during filamentation of a femtosecond laser pulse with wavefront astigmatism in air

Energy Technology Data Exchange (ETDEWEB)

Dergachev, A A; Kandidov, V P; Shlenov, S A [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation); Ionin, A A; Mokrousova, D V; Seleznev, L V; Sinitsyn, D V; Sunchugasheva, E S; Shustikova, A P [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2014-12-31

We have demonstrated experimentally and numerically the possibility of controlling parameters of plasma channels formed during filamentation of a femtosecond laser pulse by introducing astigmatism in the laser beam wavefront. It is found that weak astigmatism increases the length of the plasma channel in comparison with the case of aberration-free focusing and that strong astigmatism can cause splitting of the plasma channel into two channels located one after another on the filament axis. (interaction of laser radiation with matter. laser plasma)

Automatic pickup of arrival time of channel wave based on multi-channel constraints

Science.gov (United States)

Wang, Bao-Li

2018-03-01

Accurately detecting the arrival time of a channel wave in a coal seam is very important for in-seam seismic data processing. The arrival time greatly affects the accuracy of the channel wave inversion and the computed tomography (CT) result. However, because the signal-to-noise ratio of in-seam seismic data is reduced by the long wavelength and strong frequency dispersion, accurately timing the arrival of channel waves is extremely difficult. For this purpose, we propose a method that automatically picks up the arrival time of channel waves based on multi-channel constraints. We first estimate the Jaccard similarity coefficient of two ray paths, then apply it as a weight coefficient for stacking the multichannel dispersion spectra. The reasonableness and effectiveness of the proposed method is verified in an actual data application. Most importantly, the method increases the degree of automation and the pickup precision of the channel-wave arrival time.

Multi-channel service concept design and prototyping

NARCIS (Netherlands)

Sperling, C.P.; Simons, L.P.A.; Bouwman, W.A.G.A.

2007-01-01

Designing e-services which have to function in a multi-channel context has proved to be challenging for organizations. Previous research has shown that structured design methods are useful to structure the design process. In this paper we proceed from an existing method (which identifies

EDMC: An enhanced distributed multi-channel anti-collision algorithm for RFID reader system

Science.gov (United States)

Zhang, YuJing; Cui, Yinghua

2017-05-01

In this paper, we proposes an enhanced distributed multi-channel reader anti-collision algorithm for RFID environments which is based on the distributed multi-channel reader anti-collision algorithm for RFID environments (called DiMCA). We proposes a monitor method to decide whether reader receive the latest control news after it selected the data channel. The simulation result shows that it improves interrogation delay.

TH-CD-207B-06: Swank Factor of Segmented Scintillators in Multi-Slice CT Detectors: Pulse Height Spectra and Light Escape

Energy Technology Data Exchange (ETDEWEB)

Howansky, A; Peng, B; Lubinsky, A; Zhao, W [Stony Brook University, Stony Brook, NY (United States)

2016-06-15

Purpose: Pulse height spectra (PHS) have been used to determine the Swank factor of a scintillator by measuring fluctuations in its light output per x-ray interaction. The Swank factor and x-ray quantum efficiency of a scintillator define the upper limit to its imaging performance, i.e. DQE(0). The Swank factor below the K-edge is dominated by optical properties, i.e. variations in light escape efficiency from different depths of interaction, denoted e(z). These variations can be optimized to improve tradeoffs in x-ray absorption, light yield, and spatial resolution. This work develops a quantitative model for interpreting measured PHS, and estimating e(z) on an absolute scale. The method is used to investigate segmented ceramic GOS scintillators used in multi-slice CT detectors. Methods: PHS of a ceramic GOS plate (1 mm thickness) and segmented GOS array (1.4 mm thick) were measured at 46 keV. Signal and noise propagation through x-ray conversion gain, light escape, detection by a photomultiplier tube and dynode amplification were modeled using a cascade of stochastic gain stages. PHS were calculated with these expressions and compared to measurements. Light escape parameters were varied until modeled PHS agreed with measurements. The resulting estimates of e(z) were used to calculate PHS without measurement noise to determine the inherent Swank factor. Results: The variation in e(z) was 67.2–89.7% in the plate and 40.2–70.8% in the segmented sample, corresponding to conversion gains of 28.6–38.1 keV{sup −1} and 17.1–30.1 keV{sup −1}, respectively. The inherent Swank factors of the plate and segmented sample were 0.99 and 0.95, respectively. Conclusion: The high light escape efficiency in the ceramic GOS samples yields high Swank factors and DQE(0) in CT applications. The PHS model allows the intrinsic optical properties of scintillators to be deduced from PHS measurements, thus it provides new insights for evaluating the imaging performance of

Catalogue of response spectra for unfolding in situ gamma-ray pulse-height distributions

International Nuclear Information System (INIS)

Dymke, N.

1982-01-01

To unfold in situ gamma-ray pulse-height distributions by means of a response matrix technique, the matrix must be in keeping with the measurement geometry, detector size, and energy range to be covered by the measurements. A methodology has been described for determination of standard gamma-ray spectra needed in deriving response matrices and a spectrum catalogue compiled containing graphs and data for the 0-3 MeV (4 x 4 in. NaI(Tl)) and 0-8 MeV (1.5 x 1.5 in. NaI(Tl)) ranges. (author)

Analysis of flow distribution instability in parallel thin rectangular multi-channel system

Energy Technology Data Exchange (ETDEWEB)

Xia, G.L. [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an City 710049 (China); Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin City 150001 (China); Su, G.H., E-mail: ghsu@mail.xjtu.edu.cn [School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an City 710049 (China); Peng, M.J. [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin City 150001 (China)

2016-08-15

Highlights: • Flow distribution instability in parallel thin rectangular multi-channel system is studied using RELAP5 codes. • Flow excursion may bring parallel heating channel into the density wave oscillations region. • Flow distribution instability is more likely to happen at low power/flow ratio conditions. • The increase of channel number will not affect the flow distribution instability boundary. • Asymmetry inlet throttling and heating will make system more unstable. - Abstract: The flow distribution instability in parallel thin rectangular multi-channel system has been researched in the present study. The research model of parallel channel system is established by using RELAP5/MOD3.4 codes. The transient process of flow distribution instability is studied at imposed inlet mass flow rate and imposed pressure drop conditions. The influence of heating power, mass flow rate, system pressure and channel number on flow distribution instability are analyzed. Furthermore, the flow distribution instability of parallel two-channel system under asymmetric inlet throttling and heating power is studied. The results show that, if multi-channel system operates at the negative slope region of channel ΔP–G curve, small disturbance in pressure drop will lead to flow redistribution between parallel channels. Flow excursion may bring the operating point of heating channel into the density-wave oscillations region, this will result in out-phase or in-phase flow oscillations. Flow distribution instability is more likely to happen at low power/flow ratio conditions, the stability of parallel channel system increases with system pressure, the channel number has a little effect on system stability, but the asymmetry inlet throttling or heating power will make the system more unstable.

Channel Selection Policy in Multi-SU and Multi-PU Cognitive Radio Networks with Energy Harvesting for Internet of Everything

Directory of Open Access Journals (Sweden)

Feng Hu

2016-01-01

Full Text Available Cognitive radio, which will become a fundamental part of the Internet of Everything (IoE, has been identified as a promising solution for the spectrum scarcity. In a multi-SU and multi-PU cognitive radio network, selecting channels is a fundamental problem due to the channel competition among secondary users (SUs and packet collision between SUs and primary users (PUs. In this paper, we adopt cooperative sensing method to avoid the packet collision between SUs and PUs and focus on how to collect the spectrum sensing data of SUs for cooperative sensing. In order to reduce the channel competition among SUs, we first consider the hybrid transmission model for single SU where a SU can opportunistically access both idle channels operating either the Overlay or the Underlay model and the busy channels by using the energy harvesting technology. Then we propose a competitive set based channel selection policy for multi-SU where all SUs competing for data transmission or energy harvesting in the same channel will form a competitive set. Extensive simulations show that the proposed cooperative sensing method and the channel selection policy outperform previous solutions in terms of false alarm, average throughput, average waiting time, and energy harvesting efficiency of SUs.

Determination of pulse profile characteristics of multi spot retinal photocoagulation lasers.

Science.gov (United States)

Clarkson, Douglas McG; Makhzoum, Osama; Blackburn, John

2015-10-01

A system is described for determination of discrete pulse train characteristics of multi spot laser delivery systems for retinal photocoagulation. While photodiodes provide an ideal detection mechanism, measurement artifacts can potentially be introduced by the spatial pattern of the delivered beam relative to a discrete photodiode element. This problem was overcome by use of an integrating sphere to produce a uniform light field at the site of the photodiode detector. A basic current driven photodiode detection circuit incorporating an operational amplifier was used to generate a signal captured by a commercially available USB interface device at a rate of 10 kHz. Studies were undertaken of a Topcon Pascal Streamline laser system with output at a wavelength of 577 nm (yellow). This laser features the proprietary feature of 'Endpoint Management' ™ where pulses can be delivered as 100% of set energy levels with visible reaction on the retina and also at a reduced energy level to create potentially non visible but clinically effective lesions. Using the pulse train measurement device it was identified that the 'Endpoint Management' ™ delivery mode of pulses of lower energy was achieved by reducing the pulse duration of pulses for non-visible effect pulses while maintaining consistent beam power levels within the delivered pulse profile. The effect of eye geometry in determining safety and effectiveness of multi spot laser delivery for retinal photocoagulation is discussed. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Multi-channel fiber optic dew and humidity sensor

Science.gov (United States)

Limodehi, Hamid E.; Mozafari, Morteza; Amiri, Hesam; Légaré, François

2018-03-01

In this article, we introduce a multi-channel fiber optic dew and humidity sensor which works using a novel method based on relation between surface plasmon resonance (SPR) and water vapor condensation. The proposed sensor can instantly detect moisture or dew formation through its fiber optic channels, separately situated in different places. It enables to simultaneously measure the ambient Relative Humidity (RH) and dew point temperature of several environments with accuracy of 5%.

Pre-experiment testing of the Multi Channel Systems 16-channel preamplifier CPA16

International Nuclear Information System (INIS)

Patin, J B; Stoyer, M A; Moody, K J; Friensehner, A V

2003-01-01

The 16-channel preamplifier model CPA16 from Multi Channel Systems was studied. The CPA16 preamplifier/amplifier module is a candidate to be used as the preamplifiers and amplifiers for the focal plane detectors of the Mass Analyzer of Super Heavy Atoms (MASHA). The equipment used to test the CPA16, the results of testing the CPA16 with a pulser, a mixed 229 Th/ 148 Gd source and a 252 Cf source, and a summary of the results will be presented

Ablation mass features in multi-pulses femtosecond laser ablate molybdenum target

Science.gov (United States)

Zhao, Dongye; Gierse, Niels; Wegner, Julian; Pretzler, Georg; Oelmann, Jannis; Brezinsek, Sebastijan; Liang, Yunfeng; Neubauer, Olaf; Rasinski, Marcin; Linsmeier, Christian; Ding, Hongbin

2018-03-01

In this study, the ablation mass features related to reflectivity of bulk Molybdenum (Mo) were investigated by a Ti: Sa 6 fs laser pulse at central wavelength 790 nm. The ablated mass removal was determined using Confocal Microscopy (CM) technique. The surface reflectivity was calibrated and measured by a Lambda 950 spectrophotometer as well as a CCD camera during laser ablation. The ablation mass loss per pulse increase with the increasing of laser shots, meanwhile the surface reflectivity decrease. The multi-pulses (100 shots) ablation threshold of Mo was determined to be 0.15 J/cm2. The incubation coefficient was estimated as 0.835. The reflectivity change of the Mo target surface following multi-pulses laser ablation were studied as a function of laser ablation shots at various laser fluences from 1.07 J/cm2 to 36.23 J/cm2. The results of measured reflectivity indicate that surface reflectivity of Mo target has a significant decline in the first 3-laser pulses at the various fluences. These results are important for developing a quantitative analysis model for laser induced ablation and laser induced breakdown spectroscopy for the first wall diagnosis of EAST tokamak.

Digital Multi Channel Analyzer Enhancement

International Nuclear Information System (INIS)

Gonen, E.; Marcus, E.; Wengrowicz, U.; Beck, A.; Nir, J.; Sheinfeld, M.; Broide, A.; Tirosh, D.

2002-01-01

A cement analyzing system based on radiation spectroscopy had been developed [1], using novel digital approach for real-time, high-throughput and low-cost Multi Channel Analyzer. The performance of the developed system had a severe problem: the resulted spectrum suffered from lack of smoothness, it was very noisy and full of spikes and surges, therefore it was impossible to use this spectrum for analyzing the cement substance. This paper describes the work carried out to improve the system performance

Plasma lenses for ultrashort multi-petawatt laser pulses

Energy Technology Data Exchange (ETDEWEB)

Palastro, J. P.; Gordon, D.; Hafizi, B.; Johnson, L. A.; Peñano, J.; Hubbard, R. F.; Helle, M.; Kaganovich, D. [Naval Research Laboratory, Washington DC 20375-5346 (United States)

2015-12-15

An ideal plasma lens can provide the focusing power of a small f-number, solid-state focusing optic at a fraction of the diameter. An ideal plasma lens, however, relies on a steady-state, linear laser pulse-plasma interaction. Ultrashort multi-petawatt (MPW) pulses possess broad bandwidths and extreme intensities, and, as a result, their interaction with the plasma lens is neither steady state nor linear. Here, we examine nonlinear and time-dependent modifications to plasma lens focusing, and show that these result in chromatic and phase aberrations and amplitude distortion. We find that a plasma lens can provide enhanced focusing for 30 fs pulses with peak power up to ∼1 PW. The performance degrades through the MPW regime, until finally a focusing penalty is incurred at ∼10 PW.

Regret of Multi-Channel Bandit Game in Cognitive Radio Networks

Directory of Open Access Journals (Sweden)

Ma Jun

2016-01-01

Full Text Available The problem of how to evaluate the rate of convergence to Nash equilibrium solutions in the process of channel selection under incomplete information is studied. In this paper, the definition of regret is used to reflect the convergence rates of online algorithms. The process of selecting an idle channel for each secondary user is modeled as a multi-channel bandit game. The definition of the maximal averaged regret is given. Two existing online learning algorithms are used to obtain the Nash equilibrium for each SU. The maximal averaged regrets are used to evaluate the performances of online algorithms. When there is a pure strategy Nash equilibrium in the multi-channel bandit game, the maximal averaged regrets are finite. A cooperation mechanism is also needed in the process of calculating the maximal averaged regrets. Simulation results show the maximal averaged regrets are finite and the online algorithm with greater convergence rate has less maximal averaged regrets.

A single chip pulse processor for nuclear spectroscopy

International Nuclear Information System (INIS)

Hilsenrath, F.; Bakke, J.C.; Voss, H.D.

1985-01-01

A high performance digital pulse processor, integrated into a single gate array microcircuit, has been developed for spaceflight applications. The new approach takes advantage of the latest CMOS high speed A/D flash converters and low-power gated logic arrays. The pulse processor measures pulse height, pulse area and the required timing information (e.g. multi detector coincidence and pulse pile-up detection). The pulse processor features high throughput rate (e.g. 0.5 Mhz for 2 usec gausssian pulses) and improved differential linearity (e.g. + or - 0.2 LSB for a + or - 1 LSB A/D). Because of the parallel digital architecture of the device, the interface is microprocessor bus compatible. A satellite flight application of this module is presented for use in the X-ray imager and high energy particle spectrometers of the PEM experiment on the Upper Atmospheric Research Satellite

Microfluidic in-channel multi-electrode platform for neurotransmitter sensing

Science.gov (United States)

Kara, A.; Mathault, J.; Reitz, A.; Boisvert, M.; Tessier, F.; Greener, J.; Miled, A.

2016-03-01

In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.

Secondary Channel Bifurcation Geometry: A Multi-dimensional Problem

Science.gov (United States)

Gaeuman, D.; Stewart, R. L.

2017-12-01

The construction of secondary channels (or side channels) is a popular strategy for increasing aquatic habitat complexity in managed rivers. Such channels, however, frequently experience aggradation that prevents surface water from entering the side channels near their bifurcation points during periods of relatively low discharge. This failure to maintain an uninterrupted surface water connection with the main channel can reduce the habitat value of side channels for fish species that prefer lotic conditions. Various factors have been proposed as potential controls on the fate of side channels, including water surface slope differences between the main and secondary channels, the presence of main channel secondary circulation, transverse bed slopes, and bifurcation angle. A quantitative assessment of more than 50 natural and constructed secondary channels in the Trinity River of northern California indicates that bifurcations can assume a variety of configurations that are formed by different processes and whose longevity is governed by different sets of factors. Moreover, factors such as bifurcation angle and water surface slope vary with discharge level and are continuously distributed in space, such that they must be viewed as a multi-dimensional field rather than a single-valued attribute that can be assigned to a particular bifurcation.

New strategies for collision resolution of multi-access channel

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

Multi-access protocol is one of the commonlyapplied access control protocols,in which commonchannels is shared by multi-users(as shown inFig.1).In recent years,this protocol has been suc-cessfully applied to various communication sys-tems[1].Typical examples are satellite communica-tion system,mobile communication system,localarea net work(LAN)and metropolitan area net work(MAN).There are chiefly three kinds of Multi-ac-cess channel models,i.e.fixed allocation model,self-adjusting allocation model and rando...

Thermal Hydraulic Performance in a Solar Air Heater Channel with Multi V-Type Perforated Baffles

Directory of Open Access Journals (Sweden)

Anil Kumar

2016-07-01

Full Text Available This article presents heat transfer and fluid flow characteristics in a solar air heater (SAH channel with multi V-type perforated baffles. The flow passage has an aspect ratio of 10. The relative baffle height, relative pitch, relative baffle hole position, flow attack angle, and baffle open area ratio are 0.6, 8.0, 0.42, 60°, and 12%, respectively. The Reynolds numbers considered in the study was in the range of 3000–10,000. The re-normalization group (RNG k-ε turbulence model has been used for numerical analysis, and the optimum relative baffle width has been investigated considering relative baffle widths of 1.0–7.0.The numerical results are in good agreement with the experimental data for the range considered in the study. Multi V-type perforated baffles are shown to have better thermal performance as compared to other baffle shapes in a rectangular passage. The overall thermal hydraulic performance shows the maximum value at the relative baffle width of 5.0.

Multi-server blind quantum computation over collective-noise channels

Science.gov (United States)

Xiao, Min; Liu, Lin; Song, Xiuli

2018-03-01

Blind quantum computation (BQC) enables ordinary clients to securely outsource their computation task to costly quantum servers. Besides two essential properties, namely correctness and blindness, practical BQC protocols also should make clients as classical as possible and tolerate faults from nonideal quantum channel. In this paper, using logical Bell states as quantum resource, we propose multi-server BQC protocols over collective-dephasing noise channel and collective-rotation noise channel, respectively. The proposed protocols permit completely or almost classical client, meet the correctness and blindness requirements of BQC protocol, and are typically practical BQC protocols.

On-line gas mixing and multi-channel distribution system

International Nuclear Information System (INIS)

Kalmani, S.D.; Mondal, N.K.; Satyanarayana, B.; Verma, P.; Joshi, Avinash

2009-01-01

In this presentation, we describe a mass-flow controller based on-line gas mixing unit with the multi-channel distribution system. We highlight different aspects such as requirement, design, calibration, control and operation of this system. This unit has the capability to mix up to four different input gases and distribute over 16 output channels. Output in individual channels is controlled accurately by using capillary-based system. At present, we are using this gas mixing unit for prototype of iron calorimeter (ICAL) detector of India-based Neutrino Observatory (INO).

Emulating Spherical Wave Channel Models in Multi-probe Anechoic Chamber Setups

DEFF Research Database (Denmark)

Fan, Wei; Carreño, Xavier; Nielsen, Jesper Ødum

2015-01-01

to emulate spherical wave channel models in multi-probe anechoic chamber setups. In this paper, a technique based on the field synthesis principle is proposed to approximate spherical waves emitted from arbitrarily located point sources with arbitrary polarizations. Simulation results show that static......Spherical wave channel modeling has attracted huge research attention for massive multiple-input multiple-output (MIMO) and short-distance MIMO systems. Current research work in multi-probe anechoic chamber systems is limited to reproduce radio channels assuming planar wavefronts. There is a need...... spherical waves can be reproduced with a limited number of probes, and the field synthesis accuracy of spherical wave depends on the location of the source point....

A multi-channel AC power supply controller

International Nuclear Information System (INIS)

Su Hong; Li Xiaogang; Ma Xiaoli; Zhou Bo; Yin Weiwei

2003-01-01

A multi-channel ac power supply controller developed recently by authors is introduced briefly in this paper. This controller is a computer controlled multi-electronic-switch device. This controller was developed for the automatic control and monitoring system of a 220 V ac power supply system, it is a key front-end device of the automatic control and monitoring system. There is an electronic switch in each channel, the rated load power is ≤1 kW/each channel. Another function is to sample the 220 V ac output voltage so that computer can monitor the operation state of each electronic switch. Through these switches, the 220 V ac power supply is applied to some device or apparatus that need to be powered by 220 V ac power supply. In the design, a solid-state relay was employed as an electronic switch. This controller can be connected in cascade mode. There are 8 boxes at most can be connected in cascade mode. The length of control word is 8 bit, which contains addressing information and electronic switch state setting information. The sampling output of the controller is multiplexed. It is only one bit that indicates the operating state of an electronic switch. This controller has been used in an automatic control and monitoring system for 220 V ac power supply system

effect of the plasma ion channel on self-focusing of a Gaussian laser pulse in underdense plasma

Directory of Open Access Journals (Sweden)

Sh Irani

2013-09-01

Full Text Available  We have considered the self-focusing of a Gaussian laser pulse in unmagnetized plasma. High-intensity electromagnetic fields cause the variation of electron density in plasma. These changes in the special conditions cause the acceleration of electrons to the higher energy and velocities. Thus the equation of plasma density evolution was obtained considering the electrons ponderomotive force. Then, an equation for the width of laser pulse with a relativistic mass correction term and the effect of ion channel were derived and the propagation of high-intensity laser pulse in an underdense plasma with weak relativistic approximation was investigated. It is shown that the ratio of ion channel radius to spot size could result in different forms of self focusing for the laser pulse in plasma.

Multi-Pulsed High Hydrostatic Pressure Treatment of Foods

Directory of Open Access Journals (Sweden)

Sencer Buzrul

2015-05-01

Full Text Available Multi-pulsed high hydrostatic pressure (mpHHP treatment of foods has been investigated for more than two decades. It was reported that the mpHHP treatment, with few exceptions, is more effective than the classical or single-pulsed HHP (spHHP treatment for inactivation of microorganisms in fruit juice, dairy products, liquid whole egg, meat products, and sea foods. Moreover, the mpHHP treatment could be also used to inactivate enzymes in foods and to increase the shelf-life of foods. The effects of the mpHHP treatment of foods are summarized and the differences between the mpHHP and spHHP are also emphasized.

Using Poisson-regularized inversion of Bremsstrahlung emission to extract full electron energy distribution functions from x-ray pulse-height detector data

Science.gov (United States)

Swanson, C.; Jandovitz, P.; Cohen, S. A.

2018-02-01

We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV. The algorithm is found to out-perform current leading x-ray inversion algorithms when the error due to counting statistics is high.

Modelling multi-pulse population dynamics from ultrafast spectroscopy.

Directory of Open Access Journals (Sweden)

Luuk J G W van Wilderen

2011-03-01

Full Text Available Current advanced laser, optics and electronics technology allows sensitive recording of molecular dynamics, from single resonance to multi-colour and multi-pulse experiments. Extracting the occurring (bio- physical relevant pathways via global analysis of experimental data requires a systematic investigation of connectivity schemes. Here we present a Matlab-based toolbox for this purpose. The toolbox has a graphical user interface which facilitates the application of different reaction models to the data to generate the coupled differential equations. Any time-dependent dataset can be analysed to extract time-independent correlations of the observables by using gradient or direct search methods. Specific capabilities (i.e. chirp and instrument response function for the analysis of ultrafast pump-probe spectroscopic data are included. The inclusion of an extra pulse that interacts with a transient phase can help to disentangle complex interdependent pathways. The modelling of pathways is therefore extended by new theory (which is included in the toolbox that describes the finite bleach (orientation effect of single and multiple intense polarised femtosecond pulses on an ensemble of randomly oriented particles in the presence of population decay. For instance, the generally assumed flat-top multimode beam profile is adapted to a more realistic Gaussian shape, exposing the need for several corrections for accurate anisotropy measurements. In addition, the (selective excitation (photoselection and anisotropy of populations that interact with single or multiple intense polarised laser pulses is demonstrated as function of power density and beam profile. Using example values of real world experiments it is calculated to what extent this effectively orients the ensemble of particles. Finally, the implementation includes the interaction with multiple pulses in addition to depth averaging in optically dense samples. In summary, we show that mathematical

Modelling multi-pulse population dynamics from ultrafast spectroscopy.

Science.gov (United States)

van Wilderen, Luuk J G W; Lincoln, Craig N; van Thor, Jasper J

2011-03-21

Current advanced laser, optics and electronics technology allows sensitive recording of molecular dynamics, from single resonance to multi-colour and multi-pulse experiments. Extracting the occurring (bio-) physical relevant pathways via global analysis of experimental data requires a systematic investigation of connectivity schemes. Here we present a Matlab-based toolbox for this purpose. The toolbox has a graphical user interface which facilitates the application of different reaction models to the data to generate the coupled differential equations. Any time-dependent dataset can be analysed to extract time-independent correlations of the observables by using gradient or direct search methods. Specific capabilities (i.e. chirp and instrument response function) for the analysis of ultrafast pump-probe spectroscopic data are included. The inclusion of an extra pulse that interacts with a transient phase can help to disentangle complex interdependent pathways. The modelling of pathways is therefore extended by new theory (which is included in the toolbox) that describes the finite bleach (orientation) effect of single and multiple intense polarised femtosecond pulses on an ensemble of randomly oriented particles in the presence of population decay. For instance, the generally assumed flat-top multimode beam profile is adapted to a more realistic Gaussian shape, exposing the need for several corrections for accurate anisotropy measurements. In addition, the (selective) excitation (photoselection) and anisotropy of populations that interact with single or multiple intense polarised laser pulses is demonstrated as function of power density and beam profile. Using example values of real world experiments it is calculated to what extent this effectively orients the ensemble of particles. Finally, the implementation includes the interaction with multiple pulses in addition to depth averaging in optically dense samples. In summary, we show that mathematical modelling is

Improved Detection System Description and New Method for Accurate Calibration of Micro-Channel Plate Based Instruments and Its Use in the Fast Plasma Investigation on NASA's Magnetospheric MultiScale Mission

Science.gov (United States)

Gliese, U.; Avanov, L. A.; Barrie, A. C.; Kujawski, J. T.; Mariano, A. J.; Tucker, C. J.; Chornay, D. J.; Cao, N. T.; Gershman, D. J.; Dorelli, J. C.;

Digital pulse shape discrimination of detector data using fuzzy clustering

International Nuclear Information System (INIS)

Kumar, Abhinav; Chatterjee, A.; Ramachandran, K.; Shrivastava, A.; Mahata, K.

2011-01-01

In accelerator based experiments, data acquisition is done by CAMAC, VME and other systems. The current trend is to digitize the pulse shapes and not just the peak heights of all the input channels, by means of Flash ADCs. In view of the large number of channels involved, this leads to unprecedented data volumes. Therefore, attempts to perform a first level of analysis in real time using algorithms implemented in FPGA have become important. In the present work, digital pulse shape discrimination using fuzzy clustering has been investigated. The attempt has been to devise general purpose PSD Techniques, loosely coupled with the characteristics of detector or particle type, for particle identification. The method is applicable to neutron-gamma discrimination for liquid scintillators and charged particles detected by Si detectors

A Low-cost Multi-channel Analogue Signal Generator

CERN Document Server

Muller, F; Shen, W; Stamen, R

2009-01-01

A scalable multi-channel analogue signal generator is presented. It uses a commercial low-cost graphics card with multiple outputs in a standard PC as signal source. Each color signal serves as independent channel to generate an analogue signal. A custom-built external PCB was developed to adjust the graphics card output voltage levels for a specific task, which needed differential signals. The system furthermore comprises a software package to program the signal shape. The implementation of the signal generator is presented as well as an application where it was successfully utilized.

Experimental research for vacuum gap breakdown in high voltage multi-pulse

International Nuclear Information System (INIS)

Huang Ziping; He Jialong; Chen Sifu; Deng Jianjun; Wang Liping

2008-01-01

Base on the breakdown theory of vacuum gaps, experiments have been done to find out the breakdown electric field intensities in high voltage single-and triple-pulse for 26 vacuum gaps with different shapes. The experimental results match up to the theory and confirm the effect of the pulse-number increase on the breakdown electric field intensity. The key point to decide the macroscopical breakdown electric field intensity of a vacuum gap has been pointed out with some advises about the design of a multi-pulse linear inductive accelerator's accelerate gap. (authors)

Effect of flow rate distribution at the inlet on hydrodynamic mixing in narrow rectangular multi-channel

International Nuclear Information System (INIS)

Xu Jianjun; Chen Bingde; Wang Xiaojun

2008-01-01

Flow and heat transfer in the narrow rectangular multi-channel is widely en- countered in the engineering application, hydrodynamic mixing in the narrow rectangular multi-channel is one of the important concerns. With the help of the Computational Fluid Dynamics code CFX, the effect of flow rate distribution of the main channel at the inlet on hydrodynamic mixing in the narrow rectangular multi-channel is numerical simulated. The results show that the flow rate distributions at the inlet have a great effect on hydrodynamics mixing in multi-channel, the flow rate in the main channel doesn't change with increasing the axial mixing section when the average flow rate at the inlet is set. Hydrodynamic mixing will arise in the mixing section when the different ratio of the flow rate distribution at the inlet is set, and hydrodynamic mixing increases with the difference of the flow rate distribution at the inlet increase. The trend of the flow rate distribution of the main channel is consistent during the whole axial mixing section, and hydrodynamic mixing in former 4 mixing section is obvious. (authors)

The Art of Multi-channel Hypermedia Application Development

NARCIS (Netherlands)

Synodinos, Dionysios G.; Avgeriou, Paris

2003-01-01

The plethora of networked devices and platforms that continuously come to light, as well as the emergence of alternative ways to access the internet, have increased the demand for multi-channel access to hypermedia applications. Researchers and practitioners nowadays not only have to deal with the

A Novel Spectrally Efficient Asynchronous Multi-Channel MAC Using a Half-Duplex Transceiver for Wireless Networks

Directory of Open Access Journals (Sweden)

Abdullah Devendiran

2018-01-01

Full Text Available Multi-channel medium access control (MAC protocols maximize network performance by enabling concurrent wireless transmissions over non-interfering channels. Despite physical layer advancements, the underlying IEEE 802.11 MAC standard cannot fully exploit features and support high-performance applications. In this work, we propose the novel spectrally efficient asynchronous multi-channel MAC (SA-MMAC protocol for wireless networks using a single half-duplex transceiver. A full-duplex mode of operation on data channels reduces the signaling overhead and boosts the spectrum efficiency. A revamped contention mechanism of IEEE 802.11 addresses the multi-channel hidden terminal problem, and a jamming signal from the receiver addresses the collisions in control signals. Furthermore, the control channel is used for data transmissions to increase the bandwidth utilization but under a restricted half-duplex mode to avoid causing a bottleneck situation. The simulator is tested for correctness. The results suggest that the protocol can work well on 3, 4, or 12 concurrent channels with high node density, providing about 12.5 times more throughput than IEEE 802.11 and 18% to 95% more throughput than its multi-channel variants under saturated traffic conditions.

Multi-channel electronically scanned cryogenic pressure sensor

Science.gov (United States)

Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Kruse, Nancy M. H. (Inventor)

1995-01-01

A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multielement array. These dies are bonded at specific sites on a glass, prepatterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

A multi-channel coronal spectrophotometer.

Science.gov (United States)

Landman, D. A.; Orrall, F. Q.; Zane, R.

1973-01-01

We describe a new multi-channel coronal spectrophotometer system, presently being installed at Mees Solar Observatory, Mount Haleakala, Maui. The apparatus is designed to record and interpret intensities from many sections of the visible and near-visible spectral regions simultaneously, with relatively high spatial and temporal resolution. The detector, a thermoelectrically cooled silicon vidicon camera tube, has its central target area divided into a rectangular array of about 100,000 pixels and is read out in a slow-scan (about 2 sec/frame) mode. Instrument functioning is entirely under PDP 11/45 computer control, and interfacing is via the CAMAC system.

Dynamics of intense laser channel formation in an underdense plasma

International Nuclear Information System (INIS)

Davis, J.; Petrov, G.M.; Velikovich, A.L.

2005-01-01

Efficient guiding and propagation of multi-keV x-rays in plasmas can be achieved by dynamically modifying the media through plasma channel formation. The dynamics of plasma channel formation is studied in preformed underdense plasma irradiated by a high intensity laser. This is done by a two-dimensional model coupling laser propagation to a relativistic particle-in-cell model. For laser intensity of 10 20 W/cm 2 and a laser beam width of 5 μm the channel formation proceeds on a time scale of 60-70 fs in uniform plasma with density 10 18 cm -3 . The channel closes shortly after the rear of the laser pulse has passed due to Coulomb attraction from the ion core. Electron cavitation occurs only if the laser intensity is above a certain threshold intensity and the laser pulse duration exceeds 100 fs. X-ray generation and propagation is feasible for ultrarelativistic laser pulses with small beam width, less than ∼20 μm, and duration of more than 100 fs

A high-speed interface for multi-channel analyzer

International Nuclear Information System (INIS)

Shen Ji; Zheng Zhong; Qiao Chong; Chen Ziyu; Ye Yunxiu; Ye Zhenyu

2003-01-01

This paper presents a high-speed computer interface for multi-channel analyzer based on DMA technique. Its essential principle and operating procedure are introduced. By the detecting of γ spectrum of 137 Cs with the interface, it's proved that the interface can meet the requirements of high-speed data acquisition

A Low-cost Multi-channel Analogue Signal Generator

CERN Document Server

Müller, F; The ATLAS collaboration; Shen, W; Stamen, R

2009-01-01

A scalable multi-channel analogue signal generator is presented. It uses a commercial low-cost graphics card with multiple outputs in a standard PC as signal source. Each color signal serves as independent channel to generate an analogue signal. A custom-built external PCB was developed to adjust the graphics card output voltage levels for a specific task, which needed differential signals. The system furthermore comprises a software package to program the signal shape. The signal generator was successfully used as independent test bed for the ATLAS Level-1 Trigger Pre-Processor, providing up to 16 analogue signals.

Emitter signal separation method based on multi-level digital channelization

Science.gov (United States)

Han, Xun; Ping, Yifan; Wang, Sujun; Feng, Ying; Kuang, Yin; Yang, Xinquan

2018-02-01

To solve the problem of emitter separation under complex electromagnetic environment, a signal separation method based on multi-level digital channelization is proposed in this paper. A two-level structure which can divide signal into different channel is designed first, after that, the peaks of different channels are tracked using the track filter and the coincident signals in time domain are separated in time-frequency domain. Finally, the time domain waveforms of different signals are acquired by reverse transformation. The validness of the proposed method is proved by experiment.

Channel Power in Multi-Channel Environments

NARCIS (Netherlands)

M.G. Dekimpe (Marnik); B. Skiera (Bernd)

2004-01-01

textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

Interpretation of measured data and the resolution analysis of the RTP 4-channel pulsed radar

International Nuclear Information System (INIS)

Pavlo, P.

1993-01-01

The resolution of a 4-channel pulsed radar being built at Rijnhuisen for the RTP tokamak is analyzed. The achievable resolution mainly depends on the accuracy of the time-of-flight measurements and the number of sampling frequencies; since the technological solution and the configuration have already been set, emphasis is put on interpretation of the measured data (the inversion problem) and minimization of the overall error. For this purpose, a specific neural network - the Multi Layer Perceptron (MLP) - has successfully been applied. Central density in the range of 0.2-0.6 x 10 20 m -3 was considered, i.e., one above the critical density for all four frequencies but not so high as to restrict the measurements to just the edge of the plasma. By balancing the inversion error and the time measurement error, for a wide class of density profiles the overall error in estimating the reflection point position of between 0.72 cm (for the lowest frequency) and 0.52 cm (for the highest frequency) root mean square was obtained, assuming an RMS error of 70 ps in the time of flight measurements. This is probably much better than what could be obtained by the Abel transform. Moreover, mapping with the MLP is considerably faster, and it should be considered for routine multichannel pulsed radar data processing. (author) 2 tabs., 4 figs., 6 refs

Development of a computer program to determine the pulse-height distribution in a gamma-ray detector from an arbitrary geometry source -feasibility study

International Nuclear Information System (INIS)

Currie, G.D.; Marshall, M.

1989-03-01

The feasibility of developing a computer program suitable for evaluating the pulse-height spectrum in a gamma-ray detector from a complex geometry source has been examined. A selection of relevant programs, Monte Carlo radiation transport codes, have been identified and their applicability to this study discussed. It is proposed that the computation be performed in two parts: the evaluation of the photon fluence at the detector using a photon transport code, and calculation of the pulse-height distribution from this spectrum using response functions determined with an electron-photon transport code. The two transport codes selected to perform this procedure are MCNP (Monte Carlo Neutron Photon code), and EGS4 (Electron Gamma Shower code). (Author)

The design and implementation of a PC based multi-channel scaler system

International Nuclear Information System (INIS)

Wang Qiang; Chinese Academy of Sciences, Beijing; Jin Dapeng; Liu Zhen'an; Zhao Dixin

2007-01-01

A multi-channel scaler system is designed for the system check and status monitoring of the BESIII trigger system. It is composed of a PC, two PCI interface multi-channel scaler cards, the corresponding drivers and user programs. Total 64 signals can be scaled and monitored in real time. The scaled data are recorded locally and some of them are distributed to the online system. In this paper, the hardware structure, software development and long time running stability of the system are introduced. (authors)

Application of avalanche photodiode for soft X-ray pulse-height analyses in the Ht-7 tokamak

CERN Document Server

Shi Yue Jiang; Hu Li Qun; Sun Yan Jun; LiuSheng; Ling Bil

2002-01-01

An avalanche photodiode (APD) has been used as soft X-ray energy pulse-height analysis system for the measurement of the electron temperature on the HT-7 tokamak. The experimental results obtained with the APD with its inferior energy resolution show a little difference compared to the conventional high energy-resolution Si (Li) detector. Both numerical analysis and experimental results prove that the APD is good enough for application of the electron temperature measurement in tokamaks.

An interactive visualization tool for multi-channel confocal microscopy data in neurobiology research

KAUST Repository

Yong Wan,

2009-11-01

Confocal microscopy is widely used in neurobiology for studying the three-dimensional structure of the nervous system. Confocal image data are often multi-channel, with each channel resulting from a different fluorescent dye or fluorescent protein; one channel may have dense data, while another has sparse; and there are often structures at several spatial scales: subneuronal domains, neurons, and large groups of neurons (brain regions). Even qualitative analysis can therefore require visualization using techniques and parameters fine-tuned to a particular dataset. Despite the plethora of volume rendering techniques that have been available for many years, the techniques standardly used in neurobiological research are somewhat rudimentary, such as looking at image slices or maximal intensity projections. Thus there is a real demand from neurobiologists, and biologists in general, for a flexible visualization tool that allows interactive visualization of multi-channel confocal data, with rapid fine-tuning of parameters to reveal the three-dimensional relationships of structures of interest. Together with neurobiologists, we have designed such a tool, choosing visualization methods to suit the characteristics of confocal data and a typical biologist\\'s workflow. We use interactive volume rendering with intuitive settings for multidimensional transfer functions, multiple render modes and multi-views for multi-channel volume data, and embedding of polygon data into volume data for rendering and editing. As an example, we apply this tool to visualize confocal microscopy datasets of the developing zebrafish visual system.

Simultaneous multi-element analysis of some edible pulses using neutron activation analysis

International Nuclear Information System (INIS)

El-Sweify, F.H.; Metwally, E.; Abdel-Khalik, H.

2007-01-01

This paper comprises the application of instrumental neutron activation analysis (INAA) for multi-element determination in some edible pulse samples. These edible pulses are usually daily used in the Egyptian kitchen. These were: anise, cumin, coriander, caraway, black cumin, white kidney bean, lupine, lentil, chickpea, broad bean, peanut, almond, and fenugreek. The pulses have been analyzed as dehulled pulses, in the case of legume and oil pulses with simultaneous analysis of their respective skins. The determined elements were: Ce, Co, Cr, Cs, Eu, Fe, Hf, Rb, Sb, Sc, Sr, Th and Zn. The element content in the dehulled pulses and their respective skins has been compared. Some elements were major or minor elements where others were trace elements. Standard reference materials were used to assure quality control, accuracy and precision of the technique. (author)

Cyclic Communication and the Inseparability of MIMO Multi-way Relay Channels

KAUST Repository

Chaaban, Anas; Sezgin, Aydin

2015-01-01

The K-user MIMO multi-way relay channel (Ychannel) consisting of K users with M antennas each and a common relay node with N antennas is studied in this paper. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed for this channel. The proposed strategy is based on two steps: channel diagonalization and cyclic communication. The channel diagonalization is applied by using zero-forcing beam-forming. After channel diagonalization, the channel is decomposed into parallel sub-channels. Cyclic communication is then applied, where signal-space alignment for network-coding is used over each sub-channel. The proposed strategy achieves the optimal DoF region of the channel if N M. To prove this, a new degrees-of-freedom outer bound is derived. As a by-product, we conclude that the MIMO Y-channel is not separable, i.e., independent coding on separate sub-channels is not enough, and one has to code jointly over several sub-channels.

Cyclic Communication and the Inseparability of MIMO Multi-way Relay Channels

KAUST Repository

Chaaban, Anas

2015-10-27

The K-user MIMO multi-way relay channel (Ychannel) consisting of K users with M antennas each and a common relay node with N antennas is studied in this paper. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed for this channel. The proposed strategy is based on two steps: channel diagonalization and cyclic communication. The channel diagonalization is applied by using zero-forcing beam-forming. After channel diagonalization, the channel is decomposed into parallel sub-channels. Cyclic communication is then applied, where signal-space alignment for network-coding is used over each sub-channel. The proposed strategy achieves the optimal DoF region of the channel if N M. To prove this, a new degrees-of-freedom outer bound is derived. As a by-product, we conclude that the MIMO Y-channel is not separable, i.e., independent coding on separate sub-channels is not enough, and one has to code jointly over several sub-channels.

Pulse-shape discrimination in NE213 liquid scintillator detectors

International Nuclear Information System (INIS)

Cavallaro, M.; Tropea, S.; Agodi, C.; Assié, M.; Azaiez, F.; Boiano, C.; Bondì, M.; Cappuzzello, F.; Carbone, D.; De Napoli, M.; Séréville, N. de; Foti, A.; Linares, R.; Nicolosi, D.; Scarpaci, J.A.

2013-01-01

The 16-channel fast stretcher BaFPro module, originally developed for processing signals of Barium Fluoride scintillators, has been modified to make a high performing analog pulse-shape analysis of signals from the NE213 liquid scintillators of the EDEN neutron detector array. The module produces two Gaussian signals, whose amplitudes are proportional to the height of the fast component of the output light and to the total energy deposited into the scintillator, respectively. An in-beam test has been performed at INFN-LNS (Italy) demonstrating a low detection threshold, a good pulse-shape discrimination even at low energies and a wide dynamic range for the measurement of the neutrons energy.

E-Fulfillment and Multi-Channel Distribution – A Review

NARCIS (Netherlands)

N.A.H. Agatz (Niels); M. Fleischmann (Moritz); J.A.E.E. van Nunen (Jo)

2006-01-01

textabstractThis review addresses the specific supply chain management issues of Internet fulfillment in a multi-channel environment. It provides a systematic overview of managerial planning tasks and reviews corresponding quantitative models. In this way, we aim to enhance the understanding of

Improved stabilization scheme for computerized pulse-height analyzers

International Nuclear Information System (INIS)

Cohn, C.E.

1982-01-01

A stabilization scheme has been adapted from a 24-bit to a 16-bit computer. A precision pulse generator produces tagged reference pulses alternately of high and low amplitude. Gain and zero corrections are obtained from these and applied to each normal event. Provisions are made to make the system robust against pileup corruption of the reference pulses. (orig.)

The effect of channel height on bubble nucleation in superhydrophobic microchannels due to subcritical heating

Science.gov (United States)

Cowley, Adam; Maynes, Daniel; Crockett, Julie; Iverson, Brian

2017-11-01

This work experimentally investigates the effects of heating on laminar flow in high aspect ratio superhydrophobic (SH) microchannels. When water that is saturated with dissolved air is used, the unwetted cavities of the SH surfaces act as nucleation sites and air effervesces out of solution onto the surfaces. The microchannels consist of a rib/cavity structured SH surface, that is heated, and a glass surface that is utilized for flow visualization. Two channel heights of nominally 183 and 366 μm are considered. The friction factor-Reynolds product (fRe) is obtained via pressure drop and volumetric flow rate measurements and the temperature profile along the channel is obtained via thermocouples embedded in an aluminum block below the SH surface. Five surface types/configurations are investigated: smooth hydrophilic, smooth hydrophobic, SH with ribs perpendicular to the flow, SH with ribs parallel to the flow, and SH with both ribs parallel to the flow and sparse ribs perpendicular to the flow. Depending on the surface type/configuration, large bubbles can form and adversely affect fRe and lead to higher temperatures along the channel. Once bubbles grow large enough, they are expelled from the channel. The channel size greatly effects the residence time of the bubbles and consequently fRe and the channel temperature. This research was supported by the National Science Foundation (NSF) (Grant No. CBET-1235881) and the Utah NASA Space Grant Consortium (NASA Grant NNX15A124H).

Harnessing mode-selective nonlinear optics for on-chip multi-channel all-optical signal processing

Directory of Open Access Journals (Sweden)

Ming Ma

2016-11-01

Full Text Available All-optical signal processing based on nonlinear optical effects allows for the realization of important functions in telecommunications including wavelength conversion, optical multiplexing/demultiplexing, Fourier transformation, and regeneration, amongst others, on ultrafast time scales to support high data rate transmission. In integrated photonic subsystems, the majority of all-optical signal processing systems demonstrated to date typically process only a single channel at a time or perform a single processing function, which imposes a serious limitation on the functionality of integrated solutions. Here, we demonstrate how nonlinear optical effects can be harnessed in a mode-selective manner to perform simultaneous multi-channel (two and multi-functional optical signal processing (i.e., regenerative wavelength conversion in an integrated silicon photonic device. This approach, which can be scaled to a higher number of channels, opens up a new degree of freedom for performing a broad range of multi-channel nonlinear optical signal processing functions using a single integrated photonic device.

The possibility of multi-layer nanofabrication via atomic force microscope-based pulse electrochemical nanopatterning

Science.gov (United States)

Kim, Uk Su; Morita, Noboru; Lee, Deug Woo; Jun, Martin; Park, Jeong Woo

2017-05-01

Pulse electrochemical nanopatterning, a non-contact scanning probe lithography process using ultrashort voltage pulses, is based primarily on an electrochemical machining process using localized electrochemical oxidation between a sharp tool tip and the sample surface. In this study, nanoscale oxide patterns were formed on silicon Si (100) wafer surfaces via electrochemical surface nanopatterning, by supplying external pulsed currents through non-contact atomic force microscopy. Nanoscale oxide width and height were controlled by modulating the applied pulse duration. Additionally, protruding nanoscale oxides were removed completely by simple chemical etching, showing a depressed pattern on the sample substrate surface. Nanoscale two-dimensional oxides, prepared by a localized electrochemical reaction, can be defined easily by controlling physical and electrical variables, before proceeding further to a layer-by-layer nanofabrication process.

A multi-channel high-resolution time recorder system

International Nuclear Information System (INIS)

Zhang Lingyun; Yang Xiaojun; Song Kezhu; Wang Yanfang

2004-01-01

This paper introduces a multi-channel and high-speed time recorder system, which was originally designed to work in the experiments of quantum cryptography research. The novelty of the system is that all the hardware logic is performed by only one FPGA. The system can achieve several desirable features, such as simplicity, high resolution and high processing speed. (authors)

Propagation of an intense laser pulse in an under-dense plasma: channeling and stimulated Raman scattering

International Nuclear Information System (INIS)

Friou, A.

2012-01-01

This thesis is divided in two parts: i) the laser channeling in hundreds of microns long under-dense plasmas (0.1 nc ≤ n ≤ nc, nc being the critical density) of a laser pulse of intensity 10 18-20 W/cm 2 and duration 1-10 ps; ii) the saturation mechanisms of stimulated Raman back-scattering of a laser pulse of intensity 10 14 to 10 16 W/cm 2 and duration of about 1 ps. A parametric study was performed to study the channeling of a very intense laser pulse, using a 2D PIC (Particle In Cell) code. Various kinds of channels were obtained depending on the laser and plasma parameters, thereby reproducing and enlarging previous studies. Moreover, the channeling velocity was measured and scaling laws were established for homogeneous plasmas. They are then applied to inhomogeneous plasmas, similar to those encountered in inertial confinement fusion (ICF). It is then possible to estimate the energy necessary to channel to the critical density, an important step for the fast ignition scheme of ICF. Raman saturation was studied using numerical simulations, in order to determine if it is due to dephasing or to the growth of sidebands, using different approaches. The first is to study Raman simulations (electromagnetic) performed with kinetic PIC and Vlasov codes. The second, is to study the evolution of a plasma initialized with a distribution function after the adiabatic theory, using a Vlasov code (electrostatic). In this case, we observe the growth of a sideband, with dominant wave number and growth rate in good agreement with kinetic simulations. The saturation of the plasma wave can be caused by both saturation mechanisms. [fr

Fieldable computer system for determining gamma-ray pulse-height distributions, flux spectra, and dose rates from Little Boy

International Nuclear Information System (INIS)

Moss, C.E.; Lucas, M.C.; Tisinger, E.W.; Hamm, M.E.

1984-01-01

Our system consists of a LeCroy 3500 data acquisition system with a built-in CAMAC crate and eight bismuth-germanate detectors 7.62 cm in diameter and 7.62 cm long. Gamma-ray pulse-height distributions are acquired simultaneously for up to eight positions. The system was very carefully calibrated and characterized from 0.1 to 8.3 MeV using gamma-ray spectra from a variety of radioactive sources. By fitting the pulse-height distributions from the sources with a function containing 17 parameters, we determined theoretical repsonse functions. We use these response functions to unfold the distributions to obtain flux spectra. A flux-to-dose-rate conversion curve based on the work of Dimbylow and Francis is then used to obtain dose rates. Direct use of measured spectra and flux-to-dose-rate curves to obtain dose rates avoids the errors that can arise from spectrum dependence in simple gamma-ray dosimeter instruments. We present some gamma-ray doses for the Little Boy assembly operated at low power. These results can be used to determine the exposures of the Hiroshima survivors and thus aid in the establishment of radation exposure limits for the nuclear industry

A multi-channel photometric detector for multi-component analysis in flow injection analysis.

Science.gov (United States)

Tan, A; Huang, J; Geng, L; Xu, J; Zhao, X

1994-01-01

The detector, a multi-channel photometric detector, described in this paper was developed using multi-wavelength LEDs (light emitting diode) and phototransistors for absorbance measurement controlled by an Intel 8031 8-bit single chip microcomputer. Up to four flow cells can be attached to the detector. The LEDs and phototransistors are both inexpensive, and reliable. The results given by the detector for simultaneous determination of trace amounts of cobalt and cadmium in zinc sulphate electrolyte are reported. Because of the newly developed detector, this approach employs much less hardware apparatus than by employing conventional photometric detectors.

Pulse pile-up. I: Short pulses

International Nuclear Information System (INIS)

Wilkinson, D.H.

1990-07-01

The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

Analysis and compensation of synchronous measurement error for multi-channel laser interferometer

International Nuclear Information System (INIS)

Du, Shengwu; Hu, Jinchun; Zhu, Yu; Hu, Chuxiong

2017-01-01

Dual-frequency laser interferometer has been widely used in precision motion system as a displacement sensor, to achieve nanoscale positioning or synchronization accuracy. In a multi-channel laser interferometer synchronous measurement system, signal delays are different in the different channels, which will cause asynchronous measurement, and then lead to measurement error, synchronous measurement error (SME). Based on signal delay analysis of the measurement system, this paper presents a multi-channel SME framework for synchronous measurement, and establishes the model between SME and motion velocity. Further, a real-time compensation method for SME is proposed. This method has been verified in a self-developed laser interferometer signal processing board (SPB). The experiment result showed that, using this compensation method, at a motion velocity 0.89 m s −1 , the max SME between two measuring channels in the SPB is 1.1 nm. This method is more easily implemented and applied to engineering than the method of directly testing smaller signal delay. (paper)

Analysis and compensation of synchronous measurement error for multi-channel laser interferometer

Science.gov (United States)

Du, Shengwu; Hu, Jinchun; Zhu, Yu; Hu, Chuxiong

2017-05-01

Dual-frequency laser interferometer has been widely used in precision motion system as a displacement sensor, to achieve nanoscale positioning or synchronization accuracy. In a multi-channel laser interferometer synchronous measurement system, signal delays are different in the different channels, which will cause asynchronous measurement, and then lead to measurement error, synchronous measurement error (SME). Based on signal delay analysis of the measurement system, this paper presents a multi-channel SME framework for synchronous measurement, and establishes the model between SME and motion velocity. Further, a real-time compensation method for SME is proposed. This method has been verified in a self-developed laser interferometer signal processing board (SPB). The experiment result showed that, using this compensation method, at a motion velocity 0.89 m s-1, the max SME between two measuring channels in the SPB is 1.1 nm. This method is more easily implemented and applied to engineering than the method of directly testing smaller signal delay.

space vector pulse width modulation of a multi-level diode clamped

African Journals Online (AJOL)

ES Obe

step by step development of MATLAB /SIMULINK modeling of the space vector ..... Pulse Width Mod. of Multi-Level Diode Clamped Converter 119 powergui. Discrete, .... Load. Figure 22: Block diagram of the three level DCC design. 3 LEVEL ...

Adaptive multi-channel downlink assignment for overloaded spectrum-shared multi-antenna overlaid cellular networks

KAUST Repository

Radaydeh, Redha Mahmoud

2012-10-19

Overlaid cellular technology has been considered as a promising candidate to enhance the capacity and extend the coverage of cellular networks, particularly indoors. The deployment of small cells (e.g. femtocells and/or picocells) in an overlaid setup is expected to reduce the operational power and to function satisfactorily with the existing cellular architecture. Among the possible deployments of small-cell access points is to manage many of them to serve specific spatial locations, while reusing the available spectrum universally. This contribution considers the aforementioned scenario with the objective to serve as many active users as possible when the available downlink spectrum is overloaded. The case study is motivated by the importance of realizing universal resource sharing in overlaid networks, while reducing the load of distributing available resources, satisfying downlink multi-channel assignment, controlling the aggregate level of interference, and maintaining desired design/operation requirements. These objectives need to be achieved in distributed manner in each spatial space with as low processing load as possible when the feedback links are capacity-limited, multiple small-cell access points can be shared, and data exchange between access points can not be coordinated. This contribution is summarized as follows. An adaptive downlink multi-channel assignment scheme when multiple co-channel and shared small-cell access points are allocated to serve active users is proposed. It is assumed that the deployed access points employ isotropic antenna arrays of arbitrary sizes, operate using the open-access strategy, and transmit on shared physical channels simultaneously. Moreover, each active user can be served by a single transmit channel per each access point at a time, and can sense the concurrent interference level associated with each transmit antenna channel non-coherently. The proposed scheme aims to identify a suitable subset of transmit channels

Mitigation Technique for Receiver Performance Variation of Multi-Color Channels in Visible Light Communication

Directory of Open Access Journals (Sweden)

Yeong Min Jang

2011-06-01

Full Text Available “Green” and energy-efficient wireless communication schemes have recently experienced rapid development and garnered much interest. One such scheme is visible light communication (VLC which is being touted as one of the next generation wireless communication systems. VLC allows communication using multi-color channels that provide high data rates and illumination simultaneously. Even though VLC has many advantageous features compared with RF technologies, including visibility, ubiquitousness, high speed, high security, harmlessness for the human body and freedom of RF interference, it suffers from some problems on the receiver side, one of them being photo sensitivity dissimilarity of the receiver. The photo sensitivity characteristics of a VLC receiver such as Si photo-detector depend on the wavelength variation. The performance of the VLC receiver is not uniform towards all channel colors, but it is desirable for receivers to have the same performance on each color channel. In this paper, we propose a mitigation technique for reducing the performance variation of the receiver on multi-color channels. We show received power, SNR, BER, output current, and outage probability in our simulation for different color channels. Simulation results show that, the proposed scheme can reduce the performance variation of the VLC receiver on multi-color channels.

Multi-channel temperature measurement system for automotive battery stack

Science.gov (United States)

Lewczuk, Radoslaw; Wojtkowski, Wojciech

2017-08-01

A multi-channel temperature measurement system for monitoring of automotive battery stack is presented in the paper. The presented system is a complete battery temperature measuring system for hybrid / electric vehicles that incorporates multi-channel temperature measurements with digital temperature sensors communicating through 1-Wire buses, individual 1-Wire bus for each sensor for parallel computing (parallel measurements instead of sequential), FPGA device which collects data from sensors and translates it for CAN bus frames. CAN bus is incorporated for communication with car Battery Management System and uses additional CAN bus controller which communicates with FPGA device through SPI bus. The described system can parallel measure up to 12 temperatures but can be easily extended in the future in case of additional needs. The structure of the system as well as particular devices are described in the paper. Selected results of experimental investigations which show proper operation of the system are presented as well.

Ant Colony Optimization Algorithm for Centralized Dynamic Channel Allocation in Multi-Cell OFDMA Systems

Science.gov (United States)

Kim, Hyo-Su; Kim, Dong-Hoi

The dynamic channel allocation (DCA) scheme in multi-cell systems causes serious inter-cell interference (ICI) problem to some existing calls when channels for new calls are allocated. Such a problem can be addressed by advanced centralized DCA design that is able to minimize ICI. Thus, in this paper, a centralized DCA is developed for the downlink of multi-cell orthogonal frequency division multiple access (OFDMA) systems with full spectral reuse. However, in practice, as the search space of channel assignment for centralized DCA scheme in multi-cell systems grows exponentially with the increase of the number of required calls, channels, and cells, it becomes an NP-hard problem and is currently too complicated to find an optimum channel allocation. In this paper, we propose an ant colony optimization (ACO) based DCA scheme using a low-complexity ACO algorithm which is a kind of heuristic algorithm in order to solve the aforementioned problem. Simulation results demonstrate significant performance improvements compared to the existing schemes in terms of the grade of service (GoS) performance and the forced termination probability of existing calls without degrading the system performance of the average throughput.

Multi-channel grouping techniques for conducting reactor safety studies

International Nuclear Information System (INIS)

Waltar, A.E.; Wilburn, N.P.

1975-01-01

In conducting safety studies for postulated unprotected accidents in an LMFBR system, it is common practice to employ multi-channel coupled neutronics, thermal hydraulics computer programs such as SAS3A or MELT-III. The multichannel feature of such code systems is important if the natural fuel failure incoherencies and the resulting sodium void/fuel motion reactivity feedbacks--which have strong spatial variations--are to be properly modeled. Because of the large amounts of computer time associated with many channel runs, however, there is a strong incentive to conduct parametric studies with as few channels as possible. The paper presented is focused on methods successfully employed to accomplish this end for a study of the hypothetical unprotected transient overpower accident conducted for the FFTF

Content-Based Multi-Channel Network Coding Algorithm in the Millimeter-Wave Sensor Network

Directory of Open Access Journals (Sweden)

Kai Lin

2016-07-01

Full Text Available With the development of wireless technology, the widespread use of 5G is already an irreversible trend, and millimeter-wave sensor networks are becoming more and more common. However, due to the high degree of complexity and bandwidth bottlenecks, the millimeter-wave sensor network still faces numerous problems. In this paper, we propose a novel content-based multi-channel network coding algorithm, which uses the functions of data fusion, multi-channel and network coding to improve the data transmission; the algorithm is referred to as content-based multi-channel network coding (CMNC. The CMNC algorithm provides a fusion-driven model based on the Dempster-Shafer (D-S evidence theory to classify the sensor nodes into different classes according to the data content. By using the result of the classification, the CMNC algorithm also provides the channel assignment strategy and uses network coding to further improve the quality of data transmission in the millimeter-wave sensor network. Extensive simulations are carried out and compared to other methods. Our simulation results show that the proposed CMNC algorithm can effectively improve the quality of data transmission and has better performance than the compared methods.

MODELING MULTI-WAVELENGTH PULSE PROFILES OF THE MILLISECOND PULSAR PSR B1821–24

Energy Technology Data Exchange (ETDEWEB)

Du, Yuanjie; Shuai, Ping; Bei, Xiaomin; Chen, Shaolong; Fu, Linzhong; Huang, Liangwei; Lin, Qingqing; Meng, Jing; Wu, Yaojun; Zhang, Hengbin; Zhang, Qian; Zhang, Xinyuan [Qian Xuesen Laboratory of Space Technology, NO. 104, Youyi Road, Haidian District, Beijing 100094 (China); Qiao, Guojun, E-mail: dyj@nao.cas.cn [School of Physics, Peking University, Beijing 100871 (China)

2015-03-10

PSR B1821–24 is a solitary millisecond pulsar that radiates multi-wavelength pulsed photons. It has complex radio, X-ray, and γ-ray pulse profiles with distinct peak phase separations that challenge the traditional caustic emission models. Using the single-pole annular gap model with a suitable magnetic inclination angle (α = 40°) and viewing angle (ζ = 75°), we managed to reproduce its pulse profiles of three wavebands. It is found that the middle radio peak originated from the core gap region at high altitudes, and the other two radio peaks originated from the annular gap region at relatively low altitudes. Two peaks of both X-ray and γ-ray wavebands basically originated from the annular gap region, while the γ-ray emission generated from the core gap region contributes somewhat to the first γ-ray peak. Precisely reproducing the multi-wavelength pulse profiles of PSR B1821–24 enables us to understand emission regions of distinct wavebands and justify pulsar emission models.

Dynamic channel assignment scheme for multi-radio wireless mesh networks

CSIR Research Space (South Africa)

Kareem, TR

2008-09-01

Full Text Available This paper investigates the challenges involve in designing a dynamic channel assignment (DCA) scheme for wireless mesh networks, particularly for multi-radio systems. It motivates the need for fast switching and process coordination modules...

An Efficient VLSI Architecture for Multi-Channel Spike Sorting Using a Generalized Hebbian Algorithm

Directory of Open Access Journals (Sweden)

Ying-Lun Chen

2015-08-01

Full Text Available A novel VLSI architecture for multi-channel online spike sorting is presented in this paper. In the architecture, the spike detection is based on nonlinear energy operator (NEO, and the feature extraction is carried out by the generalized Hebbian algorithm (GHA. To lower the power consumption and area costs of the circuits, all of the channels share the same core for spike detection and feature extraction operations. Each channel has dedicated buffers for storing the detected spikes and the principal components of that channel. The proposed circuit also contains a clock gating system supplying the clock to only the buffers of channels currently using the computation core to further reduce the power consumption. The architecture has been implemented by an application-specific integrated circuit (ASIC with 90-nm technology. Comparisons to the existing works show that the proposed architecture has lower power consumption and hardware area costs for real-time multi-channel spike detection and feature extraction.

An Efficient VLSI Architecture for Multi-Channel Spike Sorting Using a Generalized Hebbian Algorithm.

Science.gov (United States)

Chen, Ying-Lun; Hwang, Wen-Jyi; Ke, Chi-En

2015-08-13

A novel VLSI architecture for multi-channel online spike sorting is presented in this paper. In the architecture, the spike detection is based on nonlinear energy operator (NEO), and the feature extraction is carried out by the generalized Hebbian algorithm (GHA). To lower the power consumption and area costs of the circuits, all of the channels share the same core for spike detection and feature extraction operations. Each channel has dedicated buffers for storing the detected spikes and the principal components of that channel. The proposed circuit also contains a clock gating system supplying the clock to only the buffers of channels currently using the computation core to further reduce the power consumption. The architecture has been implemented by an application-specific integrated circuit (ASIC) with 90-nm technology. Comparisons to the existing works show that the proposed architecture has lower power consumption and hardware area costs for real-time multi-channel spike detection and feature extraction.

An Efficient VLSI Architecture for Multi-Channel Spike Sorting Using a Generalized Hebbian Algorithm

Science.gov (United States)

Chen, Ying-Lun; Hwang, Wen-Jyi; Ke, Chi-En

2015-01-01

A novel VLSI architecture for multi-channel online spike sorting is presented in this paper. In the architecture, the spike detection is based on nonlinear energy operator (NEO), and the feature extraction is carried out by the generalized Hebbian algorithm (GHA). To lower the power consumption and area costs of the circuits, all of the channels share the same core for spike detection and feature extraction operations. Each channel has dedicated buffers for storing the detected spikes and the principal components of that channel. The proposed circuit also contains a clock gating system supplying the clock to only the buffers of channels currently using the computation core to further reduce the power consumption. The architecture has been implemented by an application-specific integrated circuit (ASIC) with 90-nm technology. Comparisons to the existing works show that the proposed architecture has lower power consumption and hardware area costs for real-time multi-channel spike detection and feature extraction. PMID:26287193

Multi-level modelling of the response of the ultraminiature proportional counter: gas gain phenomena and pulse height spectra

International Nuclear Information System (INIS)

Olko, P.; Moutarde, C.; Segur, P.

1995-01-01

The ultraminiature proportional counters, UMC, unique radiation detectors for monitoring high intensity therapy fields, designed by Kliauga and operated at Columbia University (USA), have yielded a number of pulse height distributions for photons, neutrons and ions at simulated diameters of 5-50 nm. Monte Carlo calculations of the gas gain in such a counter questioned the possibility of achieving proportionally at such low simulated diameters. The response of the UMC has now been modelled taking into account both fluctuations of energy deposited in the counter volume and its calculated gas gain. Energy deposition was calculated using the MOCA-14, MOCA-8 and TRION codes, whereby distributions of ionisations d(j) after irradiations with 137 Cs, 15 MeV neutrons and 7 MeV.amu -1 deuterons were obtained. Monte Carlo calculations of electron avalanches in UMC show that the size of the single-electron avalanche P(n) reaching the anode depends strongly on the location of the primary ionisation within the counter volume. Distributions of the size of electron avalanches for higher numbers of primary ionisations, P *j (n), were obtained by successive convolutions of P(n). Finally, the counter response was obtained by weighting P *j (n) over d(j) distributions. On comparing the measured and calculated spectra it was concluded that the previously proposed single-electron peak calibration method might not be valid for the UMC due to the excessive width and overlap of electron avalanche distributions. Better agreement between the measured and calculated spectra is found if broader electron avalanche distributions than those used in the present calculations, are assumed. (author)

LDPC-coded MIMO optical communication over the atmospheric turbulence channel using Q-ary pulse-position modulation.

Science.gov (United States)

Djordjevic, Ivan B

2007-08-06

We describe a coded power-efficient transmission scheme based on repetition MIMO principle suitable for communication over the atmospheric turbulence channel, and determine its channel capacity. The proposed scheme employs the Q-ary pulse-position modulation. We further study how to approach the channel capacity limits using low-density parity-check (LDPC) codes. Component LDPC codes are designed using the concept of pairwise-balanced designs. Contrary to the several recent publications, bit-error rates and channel capacities are reported assuming non-ideal photodetection. The atmospheric turbulence channel is modeled using the Gamma-Gamma distribution function due to Al-Habash et al. Excellent bit-error rate performance improvement, over uncoded case, is found.

Probing temporal aspects of high-order harmonic pulses via multi-colour, multi-photon ionization processes

Energy Technology Data Exchange (ETDEWEB)

Mauritsson, J [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Johnsson, P [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); Lopez-Martens, R [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); Varju, K [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); L' Huillier, A [Department of Physics, Lund Institute of Technology, PO Box 118, SE-22100 Lund (Sweden); Gaarde, M B [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Schafer, K J [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States)

2005-07-14

High-order harmonics generated through the interaction of atoms and strong laser fields are a versatile, laboratory-scale source of extreme ultraviolet (XUV) radiation on a femtosecond or even attosecond time-scale. In order to be a useful experimental tool, however, this radiation has to be well characterized, both temporally and spectrally. In this paper we discuss how multi-photon, multi-colour ionization processes can be used to completely characterize either individual harmonics or attosecond pulse trains. In particular, we discuss the influence of the intensity and duration of the probe laser, and how these parameters effect the accuracy of the XUV characterization.

Probing temporal aspects of high-order harmonic pulses via multi-colour, multi-photon ionization processes

International Nuclear Information System (INIS)

Mauritsson, J; Johnsson, P; Lopez-Martens, R; Varju, K; L'Huillier, A; Gaarde, M B; Schafer, K J

2005-01-01

High-order harmonics generated through the interaction of atoms and strong laser fields are a versatile, laboratory-scale source of extreme ultraviolet (XUV) radiation on a femtosecond or even attosecond time-scale. In order to be a useful experimental tool, however, this radiation has to be well characterized, both temporally and spectrally. In this paper we discuss how multi-photon, multi-colour ionization processes can be used to completely characterize either individual harmonics or attosecond pulse trains. In particular, we discuss the influence of the intensity and duration of the probe laser, and how these parameters effect the accuracy of the XUV characterization

A nuclear radiation multi-parameter measurement system based on pulse-shape sampling

International Nuclear Information System (INIS)

Qiu Xiaolin; Fang Guoming; Xu Peng; Di Yuming

2007-01-01

In this paper, A nuclear radiation multi-parameter measurement system based on pulse-shape sampling is introduced, including the system's characteristics, composition, operating principle, experiment data and analysis. Compared with conventional nuclear measuring apparatus, it has some remarkable advantages such as the synchronous detection using multi-parameter measurement in the same measurement platform and the general analysis of signal data by user-defined program. (authors)

Realization of a counter/timer circuit used in digital pulse height analysis in a single chip

International Nuclear Information System (INIS)

Mahmoud, I.I.

2000-01-01

This paper presents a single chip realization of a counter circuit, which is used in random signal processing and nuclear gamma ray spectrometers. The circuit contains a counter to count the repetition rate of a selected pulse train coming from a single channel analyzer circuit. Also, it contains a timer to measure the accumulation period. The timer possesses a predetermined time facility so that processing lasts for a certain adjustable predetermined period. The counter and the timer are synchronized to start and stop simultaneously at the beginning and end of the counting interval. A multiplexed BCD to 7-segment decoder/driver is also included in the circuit. The multiplexing allows the decrease of pin count of the chip.Two stages are designed, simulated for a single channel, however more stages and channels can be added by copying the designed circuits. Schematic flow of Xilinx v.1.2I is used as the design strategy with top-level schematic design containing VHDL and schematic macros

16-channel analyser with high time-resolution for multiple coincidence experiments; Selecteur a 16 canaux a temps de resolution eleve pour experiences de coincidences multiples; Ispol'zovanie shestiadtsatikanal'nogo analizatora s bol'shoj razreshayushchej sposobnost'yu po vremeni dlya opytov s mnogokratnymi sovpadeniyami; Analizador de 16 canales de elevado poder temporal de resolucion para experimentos de coincidencias multiples

Energy Technology Data Exchange (ETDEWEB)

Brandt, B; Cappeller, U [University of Marburg, Marburg, Federal Republic of Germany (Germany)

1962-04-15

In usual slow-fast-coincidence experiments such events are counted which are selected in pulse-height by means of single-channel analysers. It is desirable to extend these techniques to a simultaneous energy-analysis of the pulses, selecting pulse-heights by means of multi-channel analysers. Multi-channel analysers used to perform such multiple coincidence experiments should give information about the amplitudes of arriving pulses at a well defined time-interval after the rising of the analysed pulse. A 16-channel pulse-height analyser is described which permits the generation of a pulse-height signal 2.5 x 10{sup -6} s after pulse-rising with an uncertainty of less than {+-} 2 x 10{sup -8} s. The resolving-time is less than 5 x 10{sup -6} s, controlled by an inspector-circuit to avoid distortions arising from the pile-up of pulses. The channel width is controlled by a window-amplifier, adjustable from 1 V to 7 V. The channel-height may be selected from 7 V to 103 V in steps of 0.5 V. (author) [French] En general, dans les experiences de coincidences lentes-rapides, on compte des evenements traduits sous forme d'impulsions dont l'amplitude est selectionnee a l'aide de selecteurs a un seul canal. Il est souhaitable d'etendre cette technique a l'analyse simultanee de l'energie des impulsions, en selectionnant les amplitudes au moyen de selecteurs a canaux multiples. Les selecteurs multi-canaux utilises pour ces experiences de coincidences multiples devraient fournir une indication sur les amplitudes des impulsions d'entree a un intervalle de temps bien defini, apres la montee de l'impulsion analysee. Les auteurs decrivent un selecteur d'amplitude a 16 canaux, qui delivre un signal 2,5 {center_dot} 10{sup -6} s apres l'etablissement de l'impulsion avec une erreur inferieure a {+-} 2 {center_dot} 10{sup -8} s. Le temps de resolution, inferieur a 5 {center_dot} 10{sup -6} s, est commande par un circuit special pour eviter les derangements qui resulteraient de l

Online purchase intentions: A multi-channel store image perspective

NARCIS (Netherlands)

Verhagen, T.; van Dolen, W.

2009-01-01

The advantages of the bricks-and-clicks retail format in the battle for the online customer has been widely discussed but empirical research on it has been limited. We applied a multi-channel store image perspective to assess its influence on online purchase intentions. Drawing on a sample of 630

Salt Intrusion, Tides and Mixing in Multi-channel Estuaries

NARCIS (Netherlands)

Nguyen, A.D.

2008-01-01

Multi-channel estuaries, such as the Mekong Delta in Vietnam and the Scheldt in the Netherlands, have characteristics of both the river and the sea, forming a unique environment influenced by tidal movements of the sea and freshwater flow of the river. This study addresses a number of knowledge gaps

Highly Efficient Multi Channel Packet Forwarding with Round Robin Intermittent Periodic Transmit for Multihop Wireless Backhaul Networks

Science.gov (United States)

Furukawa, Hiroshi

2017-01-01

Round Robin based Intermittent Periodic Transmit (RR-IPT) has been proposed which achieves highly efficient multi-hop relays in multi-hop wireless backhaul networks (MWBN) where relay nodes are 2-dimensionally deployed. This paper newly investigates multi-channel packet scheduling and forwarding scheme for RR-IPT. Downlink traffic is forwarded by RR-IPT via one of the channels, while uplink traffic and part of downlink are accommodated in the other channel. By comparing IPT and carrier sense multiple access with collision avoidance (CSMA/CA) for uplink/downlink packet forwarding channel, IPT is more effective in reducing packet loss rate whereas CSMA/CA is better in terms of system throughput and packet delay improvement. PMID:29137164

A low power Multi-Channel Analyzer

International Nuclear Information System (INIS)

Anderson, G.A.; Brackenbush, L.W.

1993-06-01

The instrumentation used in nuclear spectroscopy is generally large, is not portable, and requires a lot of power. Key components of these counting systems are the computer and the Multi-Channel Analyzer (MCA). To assist in performing measurements requiring portable systems, a small, very low power MCA has been developed at Pacific Northwest Laboratory (PNL). This MCA is interfaced with a Hewlett Packard palm top computer for portable applications. The MCA can also be connected to an IBM/PC for data storage and analysis. In addition, a real-time time display mode allows the user to view the spectra as they are collected

Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

Science.gov (United States)

Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

2011-02-01

In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time.

A microcomputer based multi parametric system for nuclear data acquisition and processing

International Nuclear Information System (INIS)

Toledo Acosta B, Rene; Osorio Deliz F, Juan; Arista Romeu, Eduardo; Perez Sanchez, Reinaldo; Lopes Torres, E.

1997-01-01

A four-parameter Multi parametric System for the acquisition and processing of nuclear data is described. It is characterized for its flexibility and relatively low cost, also guaranteeing a high acquisition capacity. The system allows to be utilized in a multi parametric manner, in pulse height analysis or in many combination of both for parameter. It is described the hardware and the software of the system

Multi-channel spintronic transistor design based on magnetoelectric barriers and spin-orbital effects

International Nuclear Information System (INIS)

Fujita, T; Jalil, M B A; Tan, S G

2008-01-01

We present a spin transistor design based on spin-orbital interactions in a two-dimensional electron gas, with magnetic barriers induced by a patterned ferromagnetic gate. The proposed device overcomes certain shortcomings of previous spin transistor designs such as long device length and degradation of conductance modulation for multi-channel transport. The robustness of our device for multi-channel transport is unique in spin transistor designs based on spin-orbit coupling. The device is more practical in fabrication and experimental respects compared to previously conceived single-mode spin transistors

Pulsed Q-switched ruby laser annealing of Bi implanted Si crystals investigated by channeling

International Nuclear Information System (INIS)

Deutch, B.I.; Shih-Chang, T.; Shang-Hwai, L.; Zu-Yao, Z.; Jia-Zeng, H.; Ren-Zhi, D.; Te-Chang, C.; De-Xin, C.

1979-01-01

Channeling was used to investigate pulsed, Q switched ruby-laser annealed and thermally annealed Si single crystals implanted with 40-keV Bi ions to a dose of 10 15 atoms/cm 2 . After thermal annealing, residual damage decreased with increasing annealing temperature to a minimum value of 30% at 900 0 C. The Bi atoms in substitutional sites reached a maximum value (50%) after annealing at 750 0 C but decreased with increasing annealing temperature. Out diffusion of Bi atoms occurred at temperatures higher than 625 0 C. For comparison, the residual damage disappeared almost completely after pulsed-laser annealing (30 ns pulse width, Energy, E = 3J/cm 2 ). The concentration of Bi in Si exceeded its solid solubility by an order of magnitude; 95% of Bi atoms were annealed to substitutional sites. Laser pulses of different energies were used to investigate the efficiency of annealing. (author)

Coordinating Multi-Channel Pricing of Seasonal Goods

OpenAIRE

Preetam Basu

2012-01-01

Advancement in information technology has opened new avenues for traditional retailers to expand their operations. Pricing, which has been a critical issue, is more important than ever before as traditional retailers pursue multi-channel sales. In this paper the author studies the pricing problem of a retailer selling a seasonal product simultaneously in a ‘brick and mortar’ store as well as online. Optimal prices are derived and different product-market conditions are determined under wh...

Zinc-dependent multi-conductance channel activity in mitochondria isolated from ischemic brain.

Science.gov (United States)

Bonanni, Laura; Chachar, Mushtaque; Jover-Mengual, Teresa; Li, Hongmei; Jones, Adrienne; Yokota, Hidenori; Ofengeim, Dimitry; Flannery, Richard J; Miyawaki, Takahiro; Cho, Chang-Hoon; Polster, Brian M; Pypaert, Marc; Hardwick, J Marie; Sensi, Stefano L; Zukin, R Suzanne; Jonas, Elizabeth A

2006-06-21

Transient global ischemia is a neuronal insult that induces delayed cell death. A hallmark event in the early post-ischemic period is enhanced permeability of mitochondrial membranes. The precise mechanisms by which mitochondrial function is disrupted are, as yet, unclear. Here we show that global ischemia promotes alterations in mitochondrial membrane contact points, a rise in intramitochondrial Zn2+, and activation of large, multi-conductance channels in mitochondrial outer membranes by 1 h after insult. Mitochondrial channel activity was associated with enhanced protease activity and proteolytic cleavage of BCL-xL to generate its pro-death counterpart, deltaN-BCL-xL. The findings implicate deltaN-BCL-xL in large, multi-conductance channel activity. Consistent with this, large channel activity was mimicked by introduction of recombinant deltaN-BCL-xL to control mitochondria and blocked by introduction of a functional BCL-xL antibody to post-ischemic mitochondria via the patch pipette. Channel activity was also inhibited by nicotinamide adenine dinucleotide, indicative of a role for the voltage-dependent anion channel (VDAC) of the outer mitochondrial membrane. In vivo administration of the membrane-impermeant Zn2+ chelator CaEDTA before ischemia or in vitro application of the membrane-permeant Zn2+ chelator tetrakis-(2-pyridylmethyl) ethylenediamine attenuated channel activity, suggesting a requirement for Zn2+. These findings reveal a novel mechanism by which ischemic insults disrupt the functional integrity of the outer mitochondrial membrane and implicate deltaN-BCL-xL and VDAC in the large, Zn2+-dependent mitochondrial channels observed in post-ischemic hippocampal mitochondria.

AIRBORNE X-HH INCIDENCE ANGLE IMPACT ON CANOPY HEIGHT RETREIVAL: IMPLICATIONS FOR SPACEBORNE X-HH TANDEM-X GLOBAL CANOPY HEIGHT MODEL

Directory of Open Access Journals (Sweden)

M. L. Tighe

2012-07-01

Full Text Available To support international climate change mitigation efforts, the United Nations REDD+ initiative (Reducing Emissions from Deforestation and Degradation seeks to reduce land use induced greenhouse gas emissions to the atmosphere. It requires independent monitoring of forest cover and forest biomass information in a spatially explicit form. It is widely recognised that remote sensing is required to deliver this information. Synthetic Aperture Radar interferometry (InSAR techniques have gained traction in the last decade as a viable technology from which vegetation canopy height and bare earth elevations can be derived. The viewing geometry of a SAR sensor is side-looking where the radar pulse is transmitted out to one side of the aircraft or satellite, defining an incidence angle (θ range. The incidence angle will change from near-range (NR to far-range (FR across of the track of the SAR platform. InSAR uses image pairs and thus, contain two set of incidence angles. Changes in the InSAR incidence angles can alter the relative contributions from the vegetation canopy and the ground surface and thus, affect the retrieved vegetation canopy height. Incidence angle change is less pronounced in spaceborne data than in airborne data and mitigated somewhat when multiple InSAR-data takes are combined. This study uses NEXTMap® single- and multi-pass X-band HH polarized InSAR to derive vegetation canopy height from the scattering phase centre height (hspc. Comparisons with in situ vegetation canopy height over three test sites (Arizona-1, Minnesota-2; the effect of incidence angle changes across swath on the X-HH InSAR hspc was examined. Results indicate at steep incidence angles (θ = 35º, more exposure of lower vegetation canopy structure (e.g. tree trunks led to greater lower canopy double bounce, increased ground scattering, and decreased volume scattering. This resulted in a lower scattering phase centre height (hspc or a greater underestimation of

Theoretical and Experimental Investigations of Coincidences in Poisson Distributed Pulse Trains and Spectral Distortion Caused by Pulse Pileup.

Science.gov (United States)

Bristow, Quentin

1990-01-01

Part one of this two-part study is concerned with the multiple coincidences in pulse trains from X-ray and gamma radiation detectors which are the cause of pulse pileup. A sequence of pulses with inter-arrival times less than tau, the resolving time of the pulse-height analysis system used to acquire spectra, is called a multiple pulse string. Such strings can be classified on the basis of the number of pulses they contain, or the number of resolving times they cover. The occurrence rates of such strings are derived from theoretical considerations. Logic circuits were devised to make experimental measurements of multiple pulse string occurrence rates in the output from a NaI(Tl) scintillation detector over a wide range of count rates. Markov process theory was used to predict state transition rates in the logic circuits, enabling the experimental data to be checked rigorously for conformity with those predicted for a Poisson distribution. No fundamental discrepancies were observed. Part two of the study is concerned with a theoretical analysis of pulse pileup and the development of a discrete correction algorithm, based on the use of a function to simulate the coincidence spectrum produced by partial sums of pulses. Monte Carlo simulations, incorporating criteria for pulse pileup inherent in the operation of modern ADC's, were used to generate pileup spectra due to coincidences between two pulses, (1st order pileup) and three pulses (2nd order pileup), for different semi-Gaussian pulse shapes. Coincidences between pulses in a single channel produced a basic probability density function spectrum which can be regarded as an impulse response for a particular pulse shape. The use of a flat spectrum (identical count rates in all channels) in the simulations, and in a parallel theoretical analysis, showed the 1st order pileup distorted the spectrum to a linear ramp with a pileup tail. The correction algorithm was successfully applied to correct entire spectra for 1st and

JADSPE, Multi-Channel Gamma Spectra Unfolding Program

International Nuclear Information System (INIS)

Rikovska, J.; Stejskalova, E.

2005-01-01

1 - Description of program or function: JADSPE is a package of eight programs to process multi-channel gamma-ray spectra. The programs can be used to: - locate automatically spectral peaks and calculate their positions, areas, and full widths at half maximum (FWHM); - plot the spectra on a CALCOMP plotter, TEKTRONIX terminal or a line printer; - add or subtract several spectra with the possibility of adjusting either their start and end channels or the maxima of the chosen corresponding peaks. The JADSPE package comprises the following programs: - SPECTF: automatic location of peaks and calculation of their positions, areas and FWHMS. The standard deviations of peak parameters are also determined, and each evaluated region is plotted on the line printer. - SPECT1: The areas and FWHMs are calculated for peaks whose positions are known beforehand. The standard deviations of calculated parameters are also determined, and each evaluated region is plotted on the line printer. - PLOCHA: The peak net area is calculated by summing the channel contents in specified regions and by subtracting a linear background. - GRAPH: Spectrum plotting on the line printer. - PLTNEW: Spectrum plotting on CALCOMP plotter or on TEKTRONIX terminal. - SUMDIF: The channel contents of several gamma-ray spectra are added or subtracted. - SSPFP: The channel contents of several gamma-ray spectra are added with adjustment of the maxima of specified peaks. - SOUCET: The channel contents of several gamma-ray spectra are added with the adjustment of start and end channels of the spectra. 2 - Method of solution: Non-linear least-square fit. 3 - Restrictions on the complexity of the problem: The full energy peaks are approximated by a symmetrical Gaussian function and the underlying background is approximated by a first-order polynomial. A fixed spectrum length of 4096 channels is assumed. Maxima of: - number of peaks in one multiplet: 9; - number of peaks identified by the automatic search procedure

The impact of the multi-channel retail mix on online store choice: Does online experience matter?

OpenAIRE

Melis, Kristina; Campo, Katia; Breugelmans, Els; Lamey, Lien

2015-01-01

More and more grocery retailers are becoming multi-channel retailers, as they are opening an online alternative next to their traditional offline supermarkets. While the number of multi-channel grocery shoppers is also expanding at a fast growth rate, there are still large differences in online shopping frequency, and as a result, in the levels of experience with buying in the online grocery channel. This study wants to (i) identify the underlying drivers of online store choice and (ii) explo...

Wireless acquisition of multi-channel seismic data using the Seismobile system

Science.gov (United States)

Isakow, Zbigniew

2017-11-01

This paper describes the wireless acquisition of multi-channel seismic data using a specialized mobile system, Seismobile, designed for subsoil diagnostics for transportation routes. The paper presents examples of multi-channel seismic records obtained during system tests in a configuration with 96 channels (4 landstreamers of 24-channel) and various seismic sources. Seismic waves were generated at the same point using different sources: a 5-kg hammer, a Gisco's source with a 90-kg pile-driver, and two other the pile-drivers of 45 and 70 kg. Particular attention is paid to the synchronization of source timing, the measurement of geometry by autonomous GPS systems, and the repeatability of triggering measurements constrained by an accelerometer identifying the seismic waveform. The tests were designed to the registration, reliability, and range of the wireless transmission of survey signals. The effectiveness of the automatic numbering of measuring modules was tested as the system components were arranged and fixed to the streamers. After measurements were completed, the accuracy and speed of data downloading from the internal memory (SDHC 32GB WiFi) was determined. Additionally, the functionality of automatic battery recharging, the maximum survey duration, and the reliability of battery discharge signalling were assessed.

Galvanically Decoupled Current Source Modules for Multi-Channel Bioimpedance Measurement Systems

Directory of Open Access Journals (Sweden)

Roman Kusche

2017-10-01

Full Text Available Bioimpedance measurements have become a useful technique in the past several years in biomedical engineering. Especially, multi-channel measurements facilitate new imaging and patient monitoring techniques. While most instrumentation research has focused on signal acquisition and signal processing, this work proposes the design of an excitation current source module that can be easily implemented in existing or upcoming bioimpedance measurement systems. It is galvanically isolated to enable simultaneous multi-channel bioimpedance measurements with a very low channel-coupling. The system is based on a microcontroller in combination with a voltage-controlled current source circuit. It generates selectable sinusoidal excitation signals between 0.12 and 1.5 mA in a frequency range from 12 to 250 kHz, whereas the voltage compliance range is ±3.2 V. The coupling factor between two current sources, experimentally galvanically connected with each other, is measured to be less than −48 dB over the entire intended frequency range. Finally, suggestions for developments in the future are made.

DIFFUSION OF THE PULSED ELECTROMAGNETIC FIELD INTO THE MULTI-LAYER CORE OF INDUCTOR AT PULSED DEVICES

Directory of Open Access Journals (Sweden)

Volodymyr T. Chemerys

2008-02-01

Full Text Available  The problem of the pulsed magnetic field distribution in the cross section of the inductor core at the induction accelerator of electron beam is under consideration in this paper. Owing to multi-layer structure of the core package it has the magnetic and electric anisotropy with different speed of the field diffusion along the sheets of magnetic and across the sheets. At the pulse duration less than one microsecond the essential non-uniformity of the field along both axes of the core cross section can be found. This effect reduces the efficiency of the ferromagnetic material using with corresponding loss of the accelerator efficiency. The main conclusion of the paper consists of the necessity to check the field diffusion characteristics in the process of inductor design to be sure that the pulsed field is able to fill the cross section of the core during the pulse switching. The magnetic characteristics of the anisotropic core have been investigated in the paper by one-dimensional and two-dimensional simulation in the quasi-stationary approximation using the traditional equation of the field diffusion.

Integrated multi-channel vehicle-vehicle and vehicle-roadside communications for ITS

Science.gov (United States)

2008-12-01

This research describes a medium access control (MAC) protocol to Enable multi-channel operation for dedicated short-range communication (DSRC). In particular, we focus on the challenge of supporting potentially high-bandwidth commercial or infotainm...

Feasibility study of applying a multi-channel analysis model to on-line core monitoring system

International Nuclear Information System (INIS)

In, W. K.; Yoo, Y. J.; Hwang, D. H.; Jun, T. H.

1998-01-01

A feasibility study was performed to evaluate the effect of implementing a multi-channel analysis model in on-line core monitoring system. A simplified thermal-hydraulic model has been used in the on-line core monitoring system of digital PWR. The design procedure, core thermal margin and computation time were investigated in case of replacing the simplified model with the multi-channel analysis model. For the given ranges of limiting conditions for operation in Yonggwang Unit 3 Cycle 1, the minimum DNBR of the simplified thermal-hydraulic code CETOP-D was compared to that of the multi-channel analysis code MATRA. A CETOP-D tuning is additionally required to ensure the accurate and conservative DNBR calculation but the MATRA tuning is not necessary. MATRA appeared to increase the DNBR overpower margin from 2.5% to 6% over the CETOP-D margin. MATRA took approximately 1 second to compute DNBR on the HP9000 workstation system, which is longer than the DNBR computation time of CETOP-D. It is, however, fast enough to perform the on-line monitoring of DNBR. It can be therefore concluded that the application of the multi-channel analysis model MATRA in the on-line core monitoring system is feasible

Development of refined MCNPX-PARET multi-channel model for transient analysis in research reactors

Energy Technology Data Exchange (ETDEWEB)

Kalcheva, S.; Koonen, E. [SCK-CEN, BR2 Reactor Dept., Boeretang 200, 2400 Mol (Belgium); Olson, A. P. [RERTR Program, Nuclear Engineering Div., Argonne National Laboratory, Cass Avenue, Argonne, IL 60439 (United States)

2012-07-01

Reactivity insertion transients are often analyzed (RELAP, PARET) using a two-channel model, representing the hot assembly with specified power distribution and an average assembly representing the remainder of the core. For the analysis of protected by the reactor safety system transients and zero reactivity feedback coefficients this approximation proves to give adequate results. However, a more refined multi-channel model representing the various assemblies, coupled through the reactivity feedback effects to the whole reactor core is needed for the analysis of unprotected transients with excluded over power and period trips. In the present paper a detailed multi-channel PARET model has been developed which describes the reactor core in different clusters representing typical BR2 fuel assemblies. The distribution of power and reactivity feedback in each cluster of the reactor core is obtained from a best-estimate MCNPX calculation using the whole core geometry model of the BR2 reactor. The sensitivity of the reactor response to power, temperature and energy distributions is studied for protected and unprotected reactivity insertion transients, with zero and non-zero reactivity feedback coefficients. The detailed multi-channel model is compared vs. simplified fewer-channel models. The sensitivities of transient characteristics derived from the different models are tested on a few reactivity insertion transients with reactivity feedback from coolant temperature and density change. (authors)

Characterization of liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system

Energy Technology Data Exchange (ETDEWEB)

Lombigit, L., E-mail: lojius@nm.gov.my; Yussup, N., E-mail: nolida@nm.gov.my; Ibrahim, Maslina Mohd; Rahman, Nur Aira Abd; Rawi, M. Z. M. [Instrumentation Group, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

2015-04-29

A digital n/γ pulse shape discrimination (PSD) system is currently under development at Instrumentation and Automation Centre, Malaysian Nuclear Agency. This system aims at simultaneous detection of fast neutron and gamma ray in mixed radiations environment. This work reports the system characterization performed on the liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system. The characterization involves measurement of electron light output from the BC-501A detector and energy channels calibration of the pulse height spectra acquired with DPSD system using set of photon reference sources. The main goal of this experiment is to calibrate the ADC channel of our DPSD system, characterized the BC-501 detector and find the position of Compton edge which later could be used as threshold for the n/γ PSD experiment. The detector resolution however is worse as compared to other published data but it is expected as our detector has a smaller active volume.

Characterization of liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system

International Nuclear Information System (INIS)

Lombigit, L.; Yussup, N.; Ibrahim, Maslina Mohd; Rahman, Nur Aira Abd; Rawi, M. Z. M.

2015-01-01

A digital n/γ pulse shape discrimination (PSD) system is currently under development at Instrumentation and Automation Centre, Malaysian Nuclear Agency. This system aims at simultaneous detection of fast neutron and gamma ray in mixed radiations environment. This work reports the system characterization performed on the liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system. The characterization involves measurement of electron light output from the BC-501A detector and energy channels calibration of the pulse height spectra acquired with DPSD system using set of photon reference sources. The main goal of this experiment is to calibrate the ADC channel of our DPSD system, characterized the BC-501 detector and find the position of Compton edge which later could be used as threshold for the n/γ PSD experiment. The detector resolution however is worse as compared to other published data but it is expected as our detector has a smaller active volume

D1.3 -- Short Report on the First Draft Multi-link Channel Model

DEFF Research Database (Denmark)

Pedersen, Troels; Raulefs, Ronald; Steinboeck, Gerhard

This deliverable is a preliminary report on the activities towards multi-link channel models. It summarizes the activities and achievements of investigations of WP1 Task 1.2 in the first year of the project. In this deliverable work focuses on the characterization of the crosscorrelation of multi...

Binaural unmasking of multi-channel stimuli in bilateral cochlear implant users.

Science.gov (United States)

Van Deun, Lieselot; van Wieringen, Astrid; Francart, Tom; Büchner, Andreas; Lenarz, Thomas; Wouters, Jan

2011-10-01

Previous work suggests that bilateral cochlear implant users are sensitive to interaural cues if experimental speech processors are used to preserve accurate interaural information in the electrical stimulation pattern. Binaural unmasking occurs in adults and children when an interaural delay is applied to the envelope of a high-rate pulse train. Nevertheless, for speech perception, binaural unmasking benefits have not been demonstrated consistently, even with coordinated stimulation at both ears. The present study aimed at bridging the gap between basic psychophysical performance on binaural signal detection tasks on the one hand and binaural perception of speech in noise on the other hand. Therefore, binaural signal detection was expanded to multi-channel stimulation and biologically relevant interaural delays. A harmonic complex, consisting of three sinusoids (125, 250, and 375 Hz), was added to three 125-Hz-wide noise bands centered on the sinusoids. When an interaural delay of 700 μs was introduced, an average BMLD of 3 dB was established. Outcomes are promising in view of real-life benefits. Future research should investigate the generalization of the observed benefits for signal detection to speech perception in everyday listening situations and determine the importance of coordination of bilateral speech processors and accentuation of envelope cues.

Suprathermal Electron Generation and Channel Formation by an Ultrarelativistic Laser Pulse in an Underdense Preformed Plasma

International Nuclear Information System (INIS)

Malka, G.; Gaillard, R.; Miquel, J.L.; Rousseaux, C.; Bonnaud, G.; Busquet, M.; Lours, L.; Fuchs, J.; Pepin, H.; Fuchs, J.; Amiranoff, F.; Baton, S.D.

1997-01-01

Relativistic electrons are produced, with energies up to 20MeV, by the interaction of a high-intensity subpicosecond laser pulse (1 μm , 300 fs , 10 19 W/cm 2 ) with an underdense plasma. Two suprathermal electron populations appear with temperatures of 1 and 3MeV. In the same conditions, the laser beam transmission is increased up to 20% 30%. We observe both features along with the evidence of laser pulse channeling. A fluid model predicts a strong self-focusing of the pulse. Acceleration in the enhanced laser field seems the most likely mechanism leading to the second electron population. copyright 1997 The American Physical Society

Multi-Channel Electronically Scanned Cryogenic Pressure Sensor And Method For Making Same

Science.gov (United States)

Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Holloway, Nancy M. (Inventor)

2001-01-01

A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multi-element array. These dies are bonded at specific sites on a glass, pre-patterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

A multi-species multi-fleet bioeconomic simulation model for the English Channel artisanal fisheries

DEFF Research Database (Denmark)

Ulrich, Clara; Le Gallic, B.; Dunn, M.R.

2002-01-01

Considering the large number of technical interactions between various fishing activities, the English Channel (ICES divisions VIId and VIIe) fisheries may be regarded as one large and diverse multi-country, multi-gear and multi-species artisanal fishery, although rarely studied as such. A whole...... of the model is to study the long-term consequences of various management alternatives on the economic situation of the English and French fleets fishing in the area and on exploited resources. The model describes this feature through the links between three entities on the one hand (stocks, fleets...... and "metiers", i.e. gear x target species x fishing area), and three modules on the other hand (activity, biological production and economics). The model is described and some simulation results are presented. An example simulating a decrease of one fleet segment effort illustrates these technical interactions...

Multi-channel electrical impedance tomography for regional tissue hydration monitoring

International Nuclear Information System (INIS)

Chen, Xiaohui; Kao, Tzu-Jen; Ashe, Jeffrey M; Boverman, Gregory; Sabatini, James E; Davenport, David M

2014-01-01

Poor assessment of hydration status during hemodialysis can lead to under- or over-hydration in patients with consequences of increased morbidity and mortality. In current practice, fluid management is largely based on clinical assessments to estimate dry weight (normal hydration body weight). However, hemodialysis patients usually have co-morbidities that can make the signs of fluid status ambiguous. Therefore, achieving normal hydration status remains a major challenge for hemodialysis therapy. Electrical impedance technology has emerged as a promising method for hydration monitoring due to its non-invasive nature, low cost and ease-of-use. Conventional electrical impedance-based hydration monitoring systems employ single-channel current excitation (either 2-electrode or 4-electrode methods) to perturb and extract averaged impedance from bulk tissue and use generalized models from large populations to derive hydration estimates. In the present study, a prototype, single-frequency electrical impedance tomography (EIT) system with simultaneous multi-channel current excitation was used to enable regional hydration change detection. We demonstrated the capability to detect a difference in daily impedance change between left leg and right leg in healthy human subjects, who wore a compression sock only on one leg to reduce daily gravitational fluid accumulation. The impedance difference corresponded well with the difference of lower leg volume change between left leg and right leg measured by volumetry, which on average is ∼35 ml, accounting for 0.7% of the lower leg volume. We have demonstrated the feasibility of using multi-channel EIT to extract hydration information in different tissue layers with minimal skin interference. Our simultaneous, multi-channel current excitation approach provides an effective method to separate electrode contact impedance and skin condition artifacts from hydration signals. The prototype system has the potential to be used in

Multi-channel electrical impedance tomography for regional tissue hydration monitoring.

Science.gov (United States)

Chen, Xiaohui; Kao, Tzu-Jen; Ashe, Jeffrey M; Boverman, Gregory; Sabatini, James E; Davenport, David M

2014-06-01

Poor assessment of hydration status during hemodialysis can lead to under- or over-hydration in patients with consequences of increased morbidity and mortality. In current practice, fluid management is largely based on clinical assessments to estimate dry weight (normal hydration body weight). However, hemodialysis patients usually have co-morbidities that can make the signs of fluid status ambiguous. Therefore, achieving normal hydration status remains a major challenge for hemodialysis therapy. Electrical impedance technology has emerged as a promising method for hydration monitoring due to its non-invasive nature, low cost and ease-of-use. Conventional electrical impedance-based hydration monitoring systems employ single-channel current excitation (either 2-electrode or 4-electrode methods) to perturb and extract averaged impedance from bulk tissue and use generalized models from large populations to derive hydration estimates. In the present study, a prototype, single-frequency electrical impedance tomography (EIT) system with simultaneous multi-channel current excitation was used to enable regional hydration change detection. We demonstrated the capability to detect a difference in daily impedance change between left leg and right leg in healthy human subjects, who wore a compression sock only on one leg to reduce daily gravitational fluid accumulation. The impedance difference corresponded well with the difference of lower leg volume change between left leg and right leg measured by volumetry, which on average is ~35 ml, accounting for 0.7% of the lower leg volume. We have demonstrated the feasibility of using multi-channel EIT to extract hydration information in different tissue layers with minimal skin interference. Our simultaneous, multi-channel current excitation approach provides an effective method to separate electrode contact impedance and skin condition artifacts from hydration signals. The prototype system has the potential to be used in clinical

A Receiver-Initiated Collision-Avoidance Protocol for Multi-Channel Networks

Science.gov (United States)

2001-01-01

00-00-2001 to 00-00-2001 4. TITLE AND SUBTITLE A Receiver-Initiated Collision-Avoidance Protocol for Multi-Channel Netowrks 5a. CONTRACT NUMBER...images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 10 19a. NAME OF RESPONSIBLE

A high dynamic range pulse counting detection system for mass spectrometry.

Science.gov (United States)

Collings, Bruce A; Dima, Martian D; Ivosev, Gordana; Zhong, Feng

2014-01-30

A high dynamic range pulse counting system has been developed that demonstrates an ability to operate at up to 2e8 counts per second (cps) on a triple quadrupole mass spectrometer. Previous pulse counting detection systems have typically been limited to about 1e7 cps at the upper end of the systems dynamic range. Modifications to the detection electronics and dead time correction algorithm are described in this paper. A high gain transimpedance amplifier is employed that allows a multi-channel electron multiplier to be operated at a significantly lower bias potential than in previous pulse counting systems. The system utilises a high-energy conversion dynode, a multi-channel electron multiplier, a high gain transimpedance amplifier, non-paralysing detection electronics and a modified dead time correction algorithm. Modification of the dead time correction algorithm is necessary due to a characteristic of the pulse counting electronics. A pulse counting detection system with the capability to count at ion arrival rates of up to 2e8 cps is described. This is shown to provide a linear dynamic range of nearly five orders of magnitude for a sample of aprazolam with concentrations ranging from 0.0006970 ng/mL to 3333 ng/mL while monitoring the m/z 309.1 → m/z 205.2 transition. This represents an upward extension of the detector's linear dynamic range of about two orders of magnitude. A new high dynamic range pulse counting system has been developed demonstrating the ability to operate at up to 2e8 cps on a triple quadrupole mass spectrometer. This provides an upward extension of the detector's linear dynamic range by about two orders of magnitude over previous pulse counting systems. Copyright © 2013 John Wiley & Sons, Ltd.

High spatial resolution distributed fiber system for multi-parameter sensing based on modulated pulses.

Science.gov (United States)

Zhang, Jingdong; Zhu, Tao; Zhou, Huan; Huang, Shihong; Liu, Min; Huang, Wei

2016-11-28

We demonstrate a cost-effective distributed fiber sensing system for the multi-parameter detection of the vibration, the temperature, and the strain by integrating phase-sensitive optical time domain reflectometry (φ-OTDR) and Brillouin optical time domain reflectometry (B-OTDR). Taking advantage of the fast changing property of the vibration and the static properties of the temperature and the strain, both the width and intensity of the laser pulses are modulated and injected into the single-mode sensing fiber proportionally, so that three concerned parameters can be extracted simultaneously by only one photo-detector and one data acquisition channel. A data processing method based on Gaussian window short time Fourier transform (G-STFT) is capable of achieving high spatial resolution in B-OTDR. The experimental results show that up to 4.8kHz vibration sensing with 3m spatial resolution at 10km standard single-mode fiber can be realized, as well as the distributed temperature and stress profiles along the same fiber with 80cm spatial resolution.

A strategy for determination of test intervals of k-out-of-n multi-channel systems

International Nuclear Information System (INIS)

Cho, S.; Jiang, J.

2007-01-01

State space models for determination of the optimal test frequencies for k-out-of-n multi channel systems are developed in this paper. The analytic solutions for the optimal surveillance test frequencies are derived using the Markov process technique. The solutions show that an optimal test frequency which maximizes the target probability can be determined by decomposing the system states to 3 states based on the system configuration and success criteria. Examples of quantification of the state probabilities and the optimal test frequencies of a three-channel system and a four-channel system with different success criteria are presented. The strategy for finding the optimal test frequency developed in this paper can generally be applicable to any k-out-of-n multi-channel standby systems that involve complex testing schemes. (author)

Development of multi-channel gated integrator and PXI-DAQ system for nuclear detector arrays

International Nuclear Information System (INIS)

Kong Jie; Su Hong; Chen Zhiqiang; Dong Chengfu; Qian Yi; Gao Shanshan; Zhou Chaoyang; Lu Wan; Ye Ruiping; Ma Junbing

2010-01-01

A multi-channel gated integrator and PXI based data acquisition system have been developed for nuclear detector arrays with hundreds of detector units. The multi-channel gated integrator can be controlled by a programmable GI controller. The PXI-DAQ system consists of NI PXI-1033 chassis with several PXI-DAQ cards. The system software has a user-friendly GUI which is written in C language using LabWindows/CVI under Windows XP operating system. The performance of the PXI-DAQ system is very reliable and capable of handling event rate up to 40 kHz.

XPS: A multi-channel preamplifier-shaper IC for X-ray spectroscopy

International Nuclear Information System (INIS)

Krieger, B.; Kipnis, I.; Ludewigt, B.A.

1997-11-01

An integrated circuit featuring 48 channels of charge-sensitive preamplifiers followed by variable-gain pulse shaping amplifiers is being developed as part of an x-ray spectrometer with a highly segmented detector to handle high fluxes in synchrotron experiments. Such detector systems can provide excellent energy resolution combined with one-dimensional spatial information. The IC combines many basic spectroscopy amplifier functions with a low-noise preamplifier section to produce a unique circuit capable of driving conventional ADC modules directly. An important feature of the design is the novel CR-RC 2 pulse shaper. In this section, high-linearity transconductor circuits are required in order to provide a broad range of continuously variable peaking times while still maintaining the linearity and noise performance necessary for x-ray spectroscopy. Reported here are first measurements made on the performance of a 16-channel prototype integrated circuit. At present, the preamplifier-shaper circuit achieves an equivalent input noise of 26 electrons rms at 2 micros peaking time with a 0.2 pF external capacitor, which is similar to the capacitance of a single detector element. The design was fabricated in standard 1.2 microm CMOS technology

Hydrodynamic optical-field-ionized plasma channels

Science.gov (United States)

Shalloo, R. J.; Arran, C.; Corner, L.; Holloway, J.; Jonnerby, J.; Walczak, R.; Milchberg, H. M.; Hooker, S. M.

2018-05-01

We present experiments and numerical simulations which demonstrate that fully ionized, low-density plasma channels could be formed by hydrodynamic expansion of plasma columns produced by optical field ionization. Simulations of the hydrodynamic expansion of plasma columns formed in hydrogen by an axicon lens show the generation of 200 mm long plasma channels with axial densities of order ne(0 ) =1 ×1017cm-3 and lowest-order modes of spot size WM≈40 μ m . These simulations show that the laser energy required to generate the channels is modest: of order 1 mJ per centimeter of channel. The simulations are confirmed by experiments with a spherical lens which show the formation of short plasma channels with 1.5 ×1017cm-3≲ne(0 ) ≲1 ×1018cm-3 and 61 μ m ≳WM≳33 μ m . Low-density plasma channels of this type would appear to be well suited as multi-GeV laser-plasma accelerator stages capable of long-term operation at high pulse repetition rates.

Nuclear Excitation by a Zeptosecond Multi-MeV Laser Pulse

International Nuclear Information System (INIS)

Weidenmueller, Hans A.

2011-01-01

A zeptosecond multi-MeV laser pulse may either excite a ''plasma'' of strongly interacting nucleons or a collective mode. We derive the conditions on laser energy and photon number such that either of these scenarios is realized. We use the nuclear giant dipole resonance as a representative example, and a random-matrix description of the fine-structure states and perturbation theory as tools.

Multi-pulse orbits and chaotic dynamics in motion of parametrically excited viscoelastic moving belt

International Nuclear Information System (INIS)

Zhang Wei; Yao Minghui

2006-01-01

In this paper, the Shilnikov type multi-pulse orbits and chaotic dynamics of parametrically excited viscoelastic moving belt are studied in detail. Using Kelvin-type viscoelastic constitutive law, the equations of motion for viscoelastic moving belt with the external damping and parametric excitation are given. The four-dimensional averaged equation under the case of primary parametric resonance is obtained by directly using the method of multiple scales and Galerkin's approach to the partial differential governing equation of viscoelastic moving belt. From the averaged equations obtained here, the theory of normal form is used to give the explicit expressions of normal form with a double zero and a pair of pure imaginary eigenvalues. Based on normal form, the energy-phrase method is employed to analyze the global bifurcations and chaotic dynamics in parametrically excited viscoelastic moving belt. The global bifurcation analysis indicates that there exist the heteroclinic bifurcations and the Silnikov type multi-pulse homoclinic orbits in the averaged equation. The results obtained above mean the existence of the chaos for the Smale horseshoe sense in parametrically excited viscoelastic moving belt. The chaotic motions of viscoelastic moving belts are also found by using numerical simulation. A new phenomenon on the multi-pulse jumping orbits is observed from three-dimensional phase space

A novel portable multi-channel analyzer based on high-speed microcontroller

International Nuclear Information System (INIS)

Lou Xinghua; Yi Hongchang; Wang Yuemin

2005-01-01

This paper introduces a novel portable multi-channel analyzer (MCA) based on high-speed microcontroller. The hardware implementation and the software scenario of the MCA are discussed. The MCA has features of high speed, small size and better performances. (authors)

Channels of energy redistribution in short-pulse laser interactions with metal targets

International Nuclear Information System (INIS)

Zhigilei, Leonid V.; Ivanov, Dmitriy S.

2005-01-01

The kinetics and channels of laser energy redistribution in a target irradiated by a short, 1 ps, laser pulse is investigated in computer simulations performed with a model that combines molecular dynamics (MD) simulations with a continuum description of the laser excitation and relaxation of the conduction band electrons, based on the two-temperature model (TTM). The energy transferred from the excited electrons to the lattice splits into several parts, namely the energy of the thermal motion of the atoms, the energy of collective atomic motions associated with the relaxation of laser-induced stresses, the energy carried away from the surface region of the target by a stress wave, the energy of quasi-static anisotropic stresses, and, at laser fluences above the melting threshold, the energy transferred to the latent heat of melting and then released upon recrystallization. The presence of the non-thermal channels of energy redistribution (stress wave and quasi-static stresses), not accounted for in the conventional TTM model, can have important implications for interpretation of experimental results on the kinetics of thermal and mechanical relaxation of a target irradiated by a short laser pulse as well as on the characteristics of laser-induced phase transformations. The fraction of the non-thermal energy in the total laser energy partitioning increases with increasing laser fluence

Radial-pulse propagation and impedance characteristics of optically shuttered channel intensifier tubes

International Nuclear Information System (INIS)

Detch, J.L. Jr.; Noel, B.W.

1981-01-01

Electrically gated proximity-focused channel intensifier tubes are often used as optical shutters. Optimum nanosecond shuttering requires both understanding the electrical pulse propagation across the device structure and proper impedance matching. A distributed-transmission-line model is developed that describes analytically the voltage- and current-wave propagation characteristics as functions of time for any point on the surface. The optical gain's spatial uniformity and shutter-open times are shown to depend on the electrical pulse width and amplitude, and on the applied bias. The driving-point impedance is derived from the model and is expressed as a function of an infinite sum of terms in the complex frequency. The synthesis in terms of lumped-constant network elements is realized in first- and second-Foster equivalent circuits. Experimental impedance data are compared with the model's predictions and deviations from the ideal model are discussed

Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

Energy Technology Data Exchange (ETDEWEB)

Pérez del Pino, Ángel, E-mail: aperez@icmab.es; Cabana, Laura; Tobias, Gerard [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); György, Enikö [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); National Institute for Lasers, Plasma and Radiation Physics, P. O. Box MG 36, 76900 Bucharest V (Romania); Ballesteros, Belén [ICN2—Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain)

2014-03-07

Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

Analytical optimal pulse shapes obtained with the aid of genetic algorithms

International Nuclear Information System (INIS)

Guerrero, Rubén D.; Arango, Carlos A.; Reyes, Andrés

2015-01-01

We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions

Analytical optimal pulse shapes obtained with the aid of genetic algorithms

Energy Technology Data Exchange (ETDEWEB)

Guerrero, Rubén D., E-mail: rdguerrerom@unal.edu.co [Department of Physics, Universidad Nacional de Colombia, Bogota (Colombia); Arango, Carlos A. [Department of Chemical Sciences, Universidad Icesi, Cali (Colombia); Reyes, Andrés [Department of Chemistry, Universidad Nacional de Colombia, Bogota (Colombia)

2015-09-28

We propose a methodology to design optimal pulses for achieving quantum optimal control on molecular systems. Our approach constrains pulse shapes to linear combinations of a fixed number of experimentally relevant pulse functions. Quantum optimal control is obtained by maximizing a multi-target fitness function using genetic algorithms. As a first application of the methodology, we generated an optimal pulse that successfully maximized the yield on a selected dissociation channel of a diatomic molecule. Our pulse is obtained as a linear combination of linearly chirped pulse functions. Data recorded along the evolution of the genetic algorithm contained important information regarding the interplay between radiative and diabatic processes. We performed a principal component analysis on these data to retrieve the most relevant processes along the optimal path. Our proposed methodology could be useful for performing quantum optimal control on more complex systems by employing a wider variety of pulse shape functions.

Multi-channel EEG-based sleep stage classification with joint collaborative representation and multiple kernel learning.

Science.gov (United States)

Shi, Jun; Liu, Xiao; Li, Yan; Zhang, Qi; Li, Yingjie; Ying, Shihui

2015-10-30

Electroencephalography (EEG) based sleep staging is commonly used in clinical routine. Feature extraction and representation plays a crucial role in EEG-based automatic classification of sleep stages. Sparse representation (SR) is a state-of-the-art unsupervised feature learning method suitable for EEG feature representation. Collaborative representation (CR) is an effective data coding method used as a classifier. Here we use CR as a data representation method to learn features from the EEG signal. A joint collaboration model is established to develop a multi-view learning algorithm, and generate joint CR (JCR) codes to fuse and represent multi-channel EEG signals. A two-stage multi-view learning-based sleep staging framework is then constructed, in which JCR and joint sparse representation (JSR) algorithms first fuse and learning the feature representation from multi-channel EEG signals, respectively. Multi-view JCR and JSR features are then integrated and sleep stages recognized by a multiple kernel extreme learning machine (MK-ELM) algorithm with grid search. The proposed two-stage multi-view learning algorithm achieves superior performance for sleep staging. With a K-means clustering based dictionary, the mean classification accuracy, sensitivity and specificity are 81.10 ± 0.15%, 71.42 ± 0.66% and 94.57 ± 0.07%, respectively; while with the dictionary learned using the submodular optimization method, they are 80.29 ± 0.22%, 71.26 ± 0.78% and 94.38 ± 0.10%, respectively. The two-stage multi-view learning based sleep staging framework outperforms all other classification methods compared in this work, while JCR is superior to JSR. The proposed multi-view learning framework has the potential for sleep staging based on multi-channel or multi-modality polysomnography signals. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of cuff inflation and deflation on pulse transit time measured from ECG and multi-wavelength PPG.

Science.gov (United States)

Liu, Jing; Li, Yao; Ding, Xiao-Rong; Dai, Wen-Xuan; Zhang, Yuan-Ting

2015-01-01

Pulse transit time (PTT), which refers to the time it takes a pulse wave to travel between two arterial sites is a promising index for cuff-less blood pressure (BP) estimation, as well as non-invasive assessment of arterial functions. However, it has not been investigated whether PTTs measured from ECG and different wavelength PPG are equally affected by the arterial status. Furthermore, comparison between the changes of different PTTs can provide enlightenment on the hardware implementation of the PTT-based BP estimation method. This work mainly studied the changes of PTTs calculated from electrocardiogram (ECG) and multi-wavelength photoplethysmogram (PPG) after exerting cuff pressure on the upper arm. A four-channel PPG acquisition system was developed to collect the multi-wavelength PPG signals of red, yellow, green and blue light at the fingertip simultaneously. Ten subjects participated in the experiment and their PTTs measured from different PPG and ECG signals before and after exerting cuff pressure were compared. This study found that within one minute after the four-minute cuff inflation and deflation process, the PTT measured from ECG and yellow PPG experienced a significant increase (p0.9) compared with that before exerting cuff pressure. This indicates that PTTs calculated from different wavelength PPG have different recoverability from smooth muscle relaxation. Another interesting finding is that the PTT calculated from ECG and yellow PPG had a strong correlation (|r|>0.7) with the time difference between yellow PPG and other PPG signals, which implies the potential of the time difference between yellow PPG and other PPGs as a complementary to PTT-based model for blood pressure estimation.

Hand Motion Classification Using a Multi-Channel Surface Electromyography Sensor

Directory of Open Access Journals (Sweden)

Dong Sun

2012-01-01

Full Text Available The human hand has multiple degrees of freedom (DOF for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high.

Hand motion classification using a multi-channel surface electromyography sensor.

Science.gov (United States)

Tang, Xueyan; Liu, Yunhui; Lv, Congyi; Sun, Dong

2012-01-01

The human hand has multiple degrees of freedom (DOF) for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG) sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high.

A wireless multi-channel bioimpedance measurement system for personalized healthcare and lifestyle.

Science.gov (United States)

Ramos, Javier; Ausín, José Luis; Lorido, Antonio Manuel; Redondo, Francisco; Duque-Carrillo, Juan Francisco

2013-01-01

Miniaturized, noninvasive, wearable sensors constitute a fundamental prerequisite for pervasive, predictive, and preventive healthcare systems. In this sense, this paper presents the design, realization, and evaluation of a wireless multi-channel measurement system based on a cost-effective high-performance integrated circuit for electrical bioimpedance (EBI) measurements in the frequency range from 1 kHz to 1 MHz. The resulting on-chip spectrometer provides high measuring EBI capabilities and together with a low-cost, commercially available radio frequency transceiver device. It provides reliable wireless communication, constitutes the basic node to build EBI wireless sensor networks (EBI-WSNs). The proposed EBI-WSN behaves as a high-performance wireless multi-channel EBI spectrometer, where the number of channels is completely scalable and independently configurable to satisfy specific measurement requirements of each individual. A prototype of the EBI node leads to a very small printed circuit board of approximately 8 cm2 including chip-antenna, which can operate several years on one 3-V coin cell battery and make it suitable for long-term preventive healthcare monitoring.

Network based multi-channel digital flash X-ray imaging system

International Nuclear Information System (INIS)

Wang Jingjin; Yuan Jie; Liu Yaqiang; Lin Yong; Song Zheng; Liu Keyin; Zhang Qi; Zheng Futang

2000-01-01

A network based multi-channel digital flash X-ray imaging system has been developed. It can be used to acquire and digitize orthogonal flash X-ray images in multi-interval, and to distribute the images on the network. There is no need of films and chemical process, no anxiety of waiting and no trouble of film archiving. This system is useful for testing ballistics, jet, explode, armour-piercing and fast running machines. The system composing and acquired images are presented. The software for object separating, mass calculating, 3D positioning, speed determining and cavity reconstruction are described

Network based multi-channel digital flash X-ray imaging system

International Nuclear Information System (INIS)

Wang Jingjin; Yuan Jie; Liu Yaqiang; Lin Yong; Song Zheng; Liu Keyin

2003-01-01

A network based multi-channel digital flash X-ray imaging system has been developed. It can be used to acquire and digitize orthogonal flash X-ray images in multi-interval, and to distribute the images on the network. There is no need of films and chemical process, no anxiety of waiting and no trouble of film archiving. This system is useful for testing ballistics, jet, explode, armour-piercing and fast running machines. The system composing and acquired images of terminal ballistics are presented. The software for object separating, profile calculating and 3D cavity reconstruction are described

Multi Channels PWM Controller for Thermoelectric Cooler Using a Programmable Logic Device and Lab-Windows CVI

Directory of Open Access Journals (Sweden)

Eli FLAXER

2008-09-01

Full Text Available We present a complete design of a multi channels PID controller for Thermoelectric Cooler (TEC using a pulse width modulation (PWM technique implemented by a dedicated programmable logic device (PLD programmed by VHDL. The PID control loop is implemented by software written by National Instrument Lab-Windows CVI. Due to the fact that the implementation is by a VHDL and PLD the design is modular, as a result, the circuit is very compact in size and very low cost as compared to any commercial product. In addition, since the control loop is implemented by software running on a personal computer (PC using a C language, it is easy to adjust the controller to various environmental conditions and for a width range of sensors like: a thermo couple (TC, thermistor, resistance temperature detectors (RTD etc. We demonstrate the performance of this circuit as a controller for a small incubator using thermistor as the temperature sensor.

A 16-channel real-time digital processor for pulse-shape discrimination in multiplicity assay

International Nuclear Information System (INIS)

Joyce, Malcolm J.; Aspinall, M.D.; Cave, F.D.; Lavietes, A.

2013-06-01

In recent years, real-time neutron/γ-ray pulse-shape discrimination has become feasible for use with scintillator-based detectors that respond extremely quickly, on the order of 25 ns in terms of pulse width, and their application to a variety of nuclear material assays has been reported. For the in-situ analysis of nuclear materials, measurements are often based on the multiplicity assessment of spontaneous fission events. An example of this is the 240 Pu eff assessment stemming from long-established techniques developed for 3 He-based neutron coincidence counters when 3 He was abundant and cheap. However, such measurements when using scintillator detectors can be plagued by low detection efficiencies and low orders of coincidence (often limited to triples) if the number of detectors in use is similarly limited to 3-4 detectors. Conversely, an array of >10 detector modules arranged to optimize efficiency and multiplicity sensitivity, shifts the emphasis in terms of performance requirement to the real-time digital analyzer and, critically, to the scope remaining in the temporal processing window of these systems. In this paper we report on the design, development and commissioning of a bespoke, 16-channel real-time pulse-shape discrimination analyzer specified for the materials assay challenge summarized above. The analyzer incorporates 16 dedicated and independent high-voltage supplies along with 16 independent digital processing channels offering pulse-shape discrimination at a rate of 3 x 10 6 events per second. These functions are configured from a dedicated graphical user interface, and all settings can be adjusted on-the-fly with the analyzer effectively configured one-time-only (where desired) for subsequent plug-and-play connection, for example to a fuel bundle organic scintillation detector array. (authors)

Objective ARX Model Order Selection for Multi-Channel Human Operator Identification

NARCIS (Netherlands)

Roggenkämper, N; Pool, D.M.; Drop, F.M.; van Paassen, M.M.; Mulder, M.

2016-01-01

In manual control, the human operator primarily responds to visual inputs but may elect to make use of other available feedback paths such as physical motion, adopting a multi-channel control strategy. Hu- man operator identification procedures generally require a priori selection of the model

Random matrix theory of multi-antenna communications: the Ricean channel

International Nuclear Information System (INIS)

Moustakas, Aris L; Simon, Steven H

2005-01-01

The use of multi-antenna arrays in wireless communications through disordered media promises huge increases in the information transmission rate. It is therefore important to analyse the information capacity of such systems in realistic situations of microwave transmission, where the statistics of the transmission amplitudes (channel) may be coloured. Here, we present an approach that provides analytic expressions for the statistics, i.e. the moments of the distribution, of the mutual information for general Gaussian channel statistics. The mathematical method applies tools developed originally in the context of coherent wave propagation in disordered media, such as random matrix theory and replicas. Although it is valid formally for large antenna numbers, this approach produces extremely accurate results even for arrays with as few as two antennas. We also develop a method to analytically optimize over the input signal distribution, which enables us to calculate analytic capacities when the transmitter has knowledge of the statistics of the channel. The emphasis of this paper is on elucidating the novel mathematical methods used. We do this by analysing a specific case when the channel matrix is a complex Gaussian with arbitrary mean and unit covariance, which is usually called the Ricean channel

Control of a pulse height analyzer using an RDX workstation

International Nuclear Information System (INIS)

Montelongo, S.; Hunt, D.N.

1984-12-01

The Nuclear Chemistry Division of Lawrence Livermore National laboratory is in the midst of upgrading its radiation counting facilities to automate data acquisition and quality control. This upgrade requires control of a pulse height analyzer (PHA) from an interactive LSI-11/23 workstation running RSX-11M. The PHA is a micro-computer based multichannel analyzer system providing data acquisition, storage, display, manipulation and input/output from up to four independent acquisition interfaces. Control of the analyzer includes reading and writing energy spectra, issuing commands, and servicing device interrupts. The analyzer communicates to the host system over a 9600-baud serial line using the Digital Data Communications link level Protocol (DDCMP). We relieved the RSX workstation CPU from the DDCMP overhead by implementing a DEC compatible in-house designed DMA serial line board (the ISL-11) to communicate with the analyzer. An RSX I/O device driver was written to complete the path between the analyzer and the RSX system by providing the link between the communication board and an application task. The I/O driver is written to handle several ISL-11 cards all operating in parallel thus providing support for control of multiple analyzers from a single workstation. The RSX device driver, its design and use by application code controlling the analyzer, and its operating environment will be discussed

A Suboptimal Scheme for Multi-User Scheduling in Gaussian Broadcast Channels

KAUST Repository

Zafar, Ammar; Alouini, Mohamed-Slim; Shaqfeh, Mohammad

2014-01-01

This work proposes a suboptimal multi-user scheduling scheme for Gaussian broadcast channels which improves upon the classical single user selection, while considerably reducing complexity as compared to the optimal superposition coding with successful interference cancellation. The proposed scheme combines the two users with the maximum weighted instantaneous rate using superposition coding. The instantaneous rate and power allocation are derived in closed-form, while the long term rate of each user is derived in integral form for all channel distributions. Numerical results are then provided to characterize the prospected gains of the proposed scheme.

A Suboptimal Scheme for Multi-User Scheduling in Gaussian Broadcast Channels

KAUST Repository

Zafar, Ammar

2014-05-28

This work proposes a suboptimal multi-user scheduling scheme for Gaussian broadcast channels which improves upon the classical single user selection, while considerably reducing complexity as compared to the optimal superposition coding with successful interference cancellation. The proposed scheme combines the two users with the maximum weighted instantaneous rate using superposition coding. The instantaneous rate and power allocation are derived in closed-form, while the long term rate of each user is derived in integral form for all channel distributions. Numerical results are then provided to characterize the prospected gains of the proposed scheme.

Design of multi-channel analyzer's monitoring system based on embedded system

International Nuclear Information System (INIS)

Yang Tao; Wei Yixiang

2007-01-01

A new Multi-Channel Analyzer's Monitoring system based on ARM9 Embedded system is introduced in this paper. Some solutions to problem are also discussed during the procedure of design, installation and debugging on Linux system. The Monitoring system is developed by using MiniGUI and Linux software system API, with the functions of collecting, displaying and I/O data controlling 1024 channels datum. They are all realized in real time, with the merits of low cost, small size and portability. All these lay the foundation of developing homemade Digital and Portable nuclear spectrometers. (authors)

Comparison of experimental pulse-height distributions in germanium detectors with integrated-tiger-series-code predictions

International Nuclear Information System (INIS)

Beutler, D.E.; Halbleib, J.A.; Knott, D.P.

1989-01-01

This paper reports pulse-height distributions in two different types of Ge detectors measured for a variety of medium-energy x-ray bremsstrahlung spectra. These measurements have been compared to predictions using the integrated tiger series (ITS) Monte Carlo electron/photon transport code. In general, the authors find excellent agreement between experiments and predictions using no free parameters. These results demonstrate that the ITS codes can predict the combined bremsstrahlung production and energy deposition with good precision (within measurement uncertainties). The one region of disagreement observed occurs for low-energy (<50 keV) photons using low-energy bremsstrahlung spectra. In this case the ITS codes appear to underestimate the produced and/or absorbed radiation by almost an order of magnitude

Oxidation of ammonium sulfite by a multi-needle-to-plate gas phase pulsed corona discharge reactor

Science.gov (United States)

Ren, Hua; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

2013-03-01

The oxidation of ammonium sulfite in the ammonia-based flue gas desulfurization (FGD) process was investigated in a multi-needle-to-plate gas phase pulsed corona discharge reactor in this paper. The effect of several parameters, including capacitance and peak pulse voltage of discharge system, electrode gap and bubbling gas flow rate on the oxidation rate of ammonium sulfite was reviewed. The oxidation rate of ammonium sulfite could reach 47.2% at the capacitance, the peak pulse voltage, electrode gap and bubbling gas flow rate equal to 2 nF, -24.6 k V, 35 mm and 4 L min-1 within treatment time of 40 min The experimental results indicate that the gas phase pulsed discharge system with a multi-needle-to-plate electrode can oxide the ammonium sulfite. The oxidation rate increased with the applied capacitance and peak pulse voltage and decreased with the electrode gap. As the bubbling gas flow rate increased, the oxidation rate increased first and then tended to reach a stationary value. These results would be important for the process optimization of the (NH4)2SO3 to (NH4)2SO4 oxidation.

Notes on the apparent discordance of pulse oximetry and multi-wavelength haemoglobin photometry

NARCIS (Netherlands)

Nijland, R.; Jongsma, H.W.; Nijhuis, J.G.; Oeseburg, Berend; Zijlstra, Willem

1995-01-01

Multi-wavelength photometers, blood gas analysers and pulse oximeters are widely used to measure various oxygen-related quantities. The definitions of these quantities are not always correct. This paper gives insight in the various definitions for oxygen quantities. Furthermore, the possible

Study on a resource allocation scheme in multi-hop MIMO-OFDM systems over lognormal-rayleigh compound channels

Directory of Open Access Journals (Sweden)

LIU Jun

2015-10-01

Full Text Available For new generation wireless communication networks,this paper studies the optimization of the capacity and end-to-end throughput of the MIMO-OFDM based multi-hop relay systems.A water-filling power allocation method is proposed to improve the channel capacity and the throughput of the MIMO-OFDM system based multi-hop relay system in the Lognormal-Rayleigh shadowing compound channels.Simulations on the capacity and throughput show that the water-filling algorithm can improve the system throughput effectively in the MIMO-OFDM multi-hop relay system.

Experimental characterization of the 192 channel Clear-PEM frontend ASIC coupled to a multi-pixel APD readout of LYSO:Ce crystals

International Nuclear Information System (INIS)

Albuquerque, Edgar; Bexiga, Vasco; Bugalho, Ricardo; Carrico, Bruno; Ferreira, Claudia S.; Ferreira, Miguel; Godinho, Joaquim; Goncalves, Fernando; Leong, Carlos; Lousa, Pedro; Machado, Pedro; Moura, Rui; Neves, Pedro; Ortigao, Catarina; Piedade, Fernando; Pinheiro, Joao F.; Rego, Joel; Rivetti, Angelo; Rodrigues, Pedro; Silva, Jose C.

2009-01-01

In the framework of the Clear-PEM project for the construction of a high-resolution scanner for breast cancer imaging, a very compact and dense frontend electronics system has been developed for readout of multi-pixel S8550 Hamamatsu APDs. The frontend electronics are instrumented with a mixed-signal Application-Specific Integrated Circuit (ASIC), which incorporates 192 low-noise charge pre-amplifiers, shapers, analog memory cells and digital control blocks. Pulses are continuously stored in memory cells at clock frequency. Channels above a common threshold voltage are readout for digitization by off-chip free-sampling ADCs. The ASIC has a size of 7.3x9.8mm 2 and was implemented in a AMS 0.35μm CMOS technology. In this paper the experimental characterization of the Clear-PEM frontend ASIC, reading out multi-pixel APDs coupled to LYSO:Ce crystal matrices, is presented. The chips were mounted on a custom test board connected to six APD arrays and to the data acquisition system. Six 32-pixel LYSO:Ce crystal matrices coupled on both sides to APD arrays were readout by two test boards. All 384 channels were operational. The chip power consumption is 660 mW (3.4 mW per channel). A very stable behavior of the chip was observed, with an estimated ENC of 1200-1300e - at APD gain 100. The inter-channel noise dispersion and mean baseline variation is less than 8% and 0.5%, respectively. The spread in the gain between different channels is found to be 1.5%. Energy resolution of 16.5% at 511 keV and 12.8% at 662 keV has been measured. Timing measurements between the two APDs that readout the same crystal is extracted and compared with detailed Monte Carlo simulations. At 511 keV the measured single photon time RMS resolution is 1.30 ns, in very good agreement with the expected value of 1.34 ns.

Multi-stage pulsed laser deposition of aluminum nitride at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Duta, L. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania); Stan, G.E. [National Institute of Materials Physics, 105 bis Atomistilor Street, 077125 Magurele (Romania); Stroescu, H.; Gartner, M.; Anastasescu, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Fogarassy, Zs. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Konkoly Thege Miklos u. 29-33, H-1121 Budapest (Hungary); Mihailescu, N. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania); Szekeres, A., E-mail: szekeres@issp.bas.bg [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Bakalova, S. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, 077125 Magurele (Romania)

2016-06-30

Highlights: • Multi-stage pulsed laser deposition of aluminum nitride at different temperatures. • 800 °C seed film boosts the next growth of crystalline structures at lower temperature. • Two-stage deposited AlN samples exhibit randomly oriented wurtzite structures. • Band gap energy values increase with deposition temperature. • Correlation was observed between single- and multi-stage AlN films. - Abstract: We report on multi-stage pulsed laser deposition of aluminum nitride (AlN) on Si (1 0 0) wafers, at different temperatures. The first stage of deposition was carried out at 800 °C, the optimum temperature for AlN crystallization. In the second stage, the deposition was conducted at lower temperatures (room temperature, 350 °C or 450 °C), in ambient Nitrogen, at 0.1 Pa. The synthesized structures were analyzed by grazing incidence X-ray diffraction (GIXRD), transmission electron microscopy (TEM), atomic force microscopy and spectroscopic ellipsometry (SE). GIXRD measurements indicated that the two-stage deposited AlN samples exhibited a randomly oriented wurtzite structure with nanosized crystallites. The peaks were shifted to larger angles, indicative for smaller inter-planar distances. Remarkably, TEM images demonstrated that the high-temperature AlN “seed” layers (800 °C) promoted the growth of poly-crystalline AlN structures at lower deposition temperatures. When increasing the deposition temperature, the surface roughness of the samples exhibited values in the range of 0.4–2.3 nm. SE analyses showed structures which yield band gap values within the range of 4.0–5.7 eV. A correlation between the results of single- and multi-stage AlN depositions was observed.

A multistation pulse height analysis system based on a PDP9L computer

International Nuclear Information System (INIS)

Ellis, P.J.

1976-06-01

A PDP9L computer is used as the basis for a multistation pulse height analysis system. Each station which is equipped with an analog-to-digital converter, a display and a keyboard-printer can perform the basic operations associated with a commercial hard-wired system. The stations are independent of one another but two or more accumulating or displaying simultaneously result in a slight increase in analog-to-digital converter dead time. The keyboard-printer operates in conversational mode with no output forthcoming if incorrect characters are entered. System procedures are initiated from the station keyboard to control the display, accumulate, integrate, and read and write functions as flexibly as possible without excessively increasing the program-to-data ratio for core usage. This system was designed to enable software to be modified when different procedures become necessary, and to enable adaptation of the available equipment to other modes of accumulation and display. (author)

Scene text detection by leveraging multi-channel information and local context

Science.gov (United States)

Wang, Runmin; Qian, Shengyou; Yang, Jianfeng; Gao, Changxin

2018-03-01

As an important information carrier, texts play significant roles in many applications. However, text detection in unconstrained scenes is a challenging problem due to cluttered backgrounds, various appearances, uneven illumination, etc.. In this paper, an approach based on multi-channel information and local context is proposed to detect texts in natural scenes. According to character candidate detection plays a vital role in text detection system, Maximally Stable Extremal Regions(MSERs) and Graph-cut based method are integrated to obtain the character candidates by leveraging the multi-channel image information. A cascaded false positive elimination mechanism are constructed from the perspective of the character and the text line respectively. Since the local context information is very valuable for us, these information is utilized to retrieve the missing characters for boosting the text detection performance. Experimental results on two benchmark datasets, i.e., the ICDAR 2011 dataset and the ICDAR 2013 dataset, demonstrate that the proposed method have achieved the state-of-the-art performance.

The designing principle and implementation of multi-channel intelligence isotope thickness gauge based on multifunction card PCI-1710

International Nuclear Information System (INIS)

Zhang Bin; Zhao Shujun; Guo Maotian; He Jintian

2006-01-01

The designing principle, the constitution of system and the implementation of multi-channel intelligence isotope thickness gauge are introduced in the paper in detail, which are based on multifunction card PCI-1710. The paper also discusses the primaryprinciple of isotope thickness gauge, correct factor in measurement and complication of calibration. In the following, the whole frame of multi-channel intelligence isotope thickness gauge is given. The functions, the characteristics and the usage of multifunction card PCI-1710 are described. Furthermore, the developing process and the function modules of software are presented. Finally, the real prototype of multi-channel intelligence isotope thickness gauge is introduced, using 241 Am as a radioactive element. (authors)

Multifunctional data acquisition system based on USB and FPGA

International Nuclear Information System (INIS)

Huang Tuchen; Gong Hui; Shao Beibei

2013-01-01

A multifunctional data acquisition system based on USB and FPGA was developed. The system has four analog inputs digitalized by fast ADC. Based on flexibility of FPGA, different functions can be implemented such as waveform sampling, pulse counting, multi-channel pulse height analysis, and charge division readout process. The hardware communicates with host PC via USB interface. The Labview based user soft ware initializes the hardware, configures the running parameters, reads and processes the data as well as displays the result online. (authors)

Nanosecond electron beams compact generator

Energy Technology Data Exchange (ETDEWEB)

Konkin, D V; Nagovitsin, A Yu; Pavlov, S S; Popkov, N F [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation)

1997-12-31

A small-scale accelerator providing a storage energy of 40 J, electron energy of 200 keV, beam current released into air of 1 kA, and current pulse duration of 30-40 ns at the half-height is described. The multi-channel commutation is implemented in the accelerator capacitive energy storage, ensuring an output current pulse front of 10 ns, while the inductiveness is 120 nH. The gross weight of the device is approximately 100 kg. (author). 4 figs., 6 refs.

Nanosecond electron beams compact generator

International Nuclear Information System (INIS)

Konkin, D.V.; Nagovitsin, A.Yu.; Pavlov, S.S.; Popkov, N.F.

1996-01-01

A small-scale accelerator providing a storage energy of 40 J, electron energy of 200 keV, beam current released into air of 1 kA, and current pulse duration of 30-40 ns at the half-height is described. The multi-channel commutation is implemented in the accelerator capacitive energy storage, ensuring an output current pulse front of 10 ns, while the inductiveness is 120 nH. The gross weight of the device is approximately 100 kg. (author). 4 figs., 6 refs

Multi-carrier Communications over Time-varying Acoustic Channels

Science.gov (United States)

Aval, Yashar M.

Acoustic communication is an enabling technology for many autonomous undersea systems, such as those used for ocean monitoring, offshore oil and gas industry, aquaculture, or port security. There are three main challenges in achieving reliable high-rate underwater communication: the bandwidth of acoustic channels is extremely limited, the propagation delays are long, and the Doppler distortions are more pronounced than those found in wireless radio channels. In this dissertation we focus on assessing the fundamental limitations of acoustic communication, and designing efficient signal processing methods that cam overcome these limitations. We address the fundamental question of acoustic channel capacity (achievable rate) for single-input-multi-output (SIMO) acoustic channels using a per-path Rician fading model, and focusing on two scenarios: narrowband channels where the channel statistics can be approximated as frequency- independent, and wideband channels where the nominal path loss is frequency-dependent. In each scenario, we compare several candidate power allocation techniques, and show that assigning uniform power across all frequencies for the first scenario, and assigning uniform power across a selected frequency-band for the second scenario, are the best practical choices in most cases, because the long propagation delay renders the feedback information outdated for power allocation based on the estimated channel response. We quantify our results using the channel information extracted form the 2010 Mobile Acoustic Communications Experiment (MACE'10). Next, we focus on achieving reliable high-rate communication over underwater acoustic channels. Specifically, we investigate orthogonal frequency division multiplexing (OFDM) as the state-of-the-art technique for dealing with frequency-selective multipath channels, and propose a class of methods that compensate for the time-variation of the underwater acoustic channel. These methods are based on multiple

Remote Sensing of Cloud Top Heights Using the Research Scanning Polarimeter

Science.gov (United States)

Sinclair, Kenneth; van Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John; Wasilewski, Andrzej

2015-01-01

Clouds cover roughly two thirds of the globe and act as an important regulator of Earth's radiation budget. Of these, multilayered clouds occur about half of the time and are predominantly two-layered. Changes in cloud top height (CTH) have been predicted by models to have a globally averaged positive feedback, however observational changes in CTH have shown uncertain results. Additional CTH observations are necessary to better and quantify the effect. Improved CTH observations will also allow for improved sub-grid parameterizations in large-scale models and accurate CTH information is important when studying variations in freezing point and cloud microphysics. NASA's airborne Research Scanning Polarimeter (RSP) is able to measure cloud top height using a novel multi-angular contrast approach. RSP scans along the aircraft track and obtains measurements at 152 viewing angles at any aircraft location. The approach presented here aggregates measurements from multiple scans to a single location at cloud altitude using a correlation function designed to identify the location-distinct features in each scan. During NASAs SEAC4RS air campaign, the RSP was mounted on the ER-2 aircraft along with the Cloud Physics Lidar (CPL), which made simultaneous measurements of CTH. The RSPs unique method of determining CTH is presented. The capabilities of using single and combinations of channels within the approach are investigated. A detailed comparison of RSP retrieved CTHs with those of CPL reveal the accuracy of the approach. Results indicate a strong ability for the RSP to accurately identify cloud heights. Interestingly, the analysis reveals an ability for the approach to identify multiple cloud layers in a single scene and estimate the CTH of each layer. Capabilities and limitations of identifying single and multiple cloud layers heights are explored. Special focus is given to sources of error in the method including optically thin clouds, physically thick clouds, multi

Nanosecond pulsed electric fields depolarize transmembrane potential via voltage-gated K+, Ca2+ and TRPM8 channels in U87 glioblastoma cells.

Science.gov (United States)

Burke, Ryan C; Bardet, Sylvia M; Carr, Lynn; Romanenko, Sergii; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

2017-10-01

Nanosecond pulsed electric fields (nsPEFs) have a variety of applications in the biomedical and biotechnology industries. Cancer treatment has been at the forefront of investigations thus far as nsPEFs permeabilize cellular and intracellular membranes leading to apoptosis and necrosis. nsPEFs may also influence ion channel gating and have the potential to modulate cell physiology without poration of the membrane. This phenomenon was explored using live cell imaging and a sensitive fluorescent probe of transmembrane voltage in the human glioblastoma cell line, U87 MG, known to express a number of voltage-gated ion channels. The specific ion channels involved in the nsPEF response were screened using a membrane potential imaging approach and a combination of pharmacological antagonists and ion substitutions. It was found that a single 10ns pulsed electric field of 34kV/cm depolarizes the transmembrane potential of cells by acting on specific voltage-sensitive ion channels; namely the voltage and Ca2 + gated BK potassium channel, L- and T-type calcium channels, and the TRPM8 transient receptor potential channel. Copyright © 2017 Elsevier B.V. All rights reserved.

Multimode pulse counter

International Nuclear Information System (INIS)

Natanzon, D.D.

1982-01-01

A pulse counter with code conversion is described. The counter is based on the integrated circuits of direct-counting devices of medium integration. The counter ensures various modes of pulse counting depending on the logical control signals: reversible, two-channel summing, one-channel summing binary, summing with ''storage'' signal code fixation without interrupting pulse counting. Arrangement of the suggested structure as a microcircuit of medium integration might contribute to reduction in the counter type nomenclature in digital families of widely used integrated circuits

Personalized multi-channel headphone sound reproduction based on active noise cancellation

NARCIS (Netherlands)

Schobben, D.W.E.; Aarts, R.M.

2005-01-01

A system for headphone signal processing is discussed which gives a listener the same impression as listening to a multi-channel loudspeaker set-up. It is important that this processing is optimized for each individual listener. If this is not the case, large localization errors may occur. In the

Guiding of short, intense laser pulses through solid guides and preformed plasma channels

International Nuclear Information System (INIS)

Borghesi, M.; Mackinnon, A.J.; Gaillard, R.; Malka, G.; Vickers, C.; Willi, O.; Blanchot, N.; Miquel, J.L.; Canaud, B.; Davies, J.R.; Malka, G.; Offenberger, A.A.

2000-01-01

In a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Commissariat a l'Energie Atomique, Limeil (France), various techniques of guiding ultra-intense laser pulses over distances exceeding the natural diffraction length were investigated. Efficient guiding was demonstrated both through density channels formed in an underdense plasma by an intense prepulse and through solid guides (hollow capillary tubes). Indication of collimated fast electron propagation though solid targets has also been obtained. (authors)

Short-pulse propagation in fiber optical parametric amplifiers

DEFF Research Database (Denmark)

Cristofori, Valentina

Fiber optical parametric amplifiers (FOPAs) are attractive because they can provide large gain over a broad range of central wavelengths, depending only on the availability of a suitable pump laser. In addition, FOPAs are suitable for the realization of all-optical signal processing functionalities...... transfer can be reduced in saturated F OPAs. In order to characterize propagation impairments such as dispersion and Kerr effect, affecting signals reaching multi-terabit per second per channel, short pulses on the order of 500 fs need to be considered. Therefore, a short pulses fiber laser source...... is implemented to obtain an all-fiber system. The advantages of all fiber-systems are related to their reliability, long-term stability and compactness. Fiber optical parametric chirped pulse amplification is promising for the amplification of such signals thanks to the inherent compatibility of FOPAs with fiber...

Proposal for a fast, zero suppressing circuit for the digitization of analog pulses over long memory times

International Nuclear Information System (INIS)

Bourgeois, F.

1984-01-01

This report describes the design principles of a fast (100 MHz) time and pulse height digitizer that can record up to 15 analog pulses over 10-80 μs memory times. Unlike other triggered circuits prepulse samples are recorded without the help of an analog delay line. The low power requirements of the circuit as well as its fast read-out characteristics make it very attractive for detectors with many digitizing channels. Conventional circuits are described as a reference for the evaluation of this new design. An ECL 10 K implementation of the circuit is presented in the third section. (orig.)

Application of a multi-channel system for continuous monitoring and an early warning system.

Science.gov (United States)

Lee, J H; Song, C H; Kim, B C; Gu, M B

2006-01-01

A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system.

Multi-channel counter-current chromatography for high-throughput fractionation of natural products for drug discovery.

Science.gov (United States)

Wu, Shihua; Yang, Lu; Gao, Yuan; Liu, Xiaoyue; Liu, Feiyan

2008-02-08

A multi-channel counter-current chromatography (CCC) method has been designed and fabricated for the high-throughput fractionation of natural products without complications sometimes encountered with other conventional chromatographic systems, such as irreversible adsorptive constituent losses and deactivation, tailing of solute peaks and contamination. It has multiple independent CCC channels and each channel connects independent separation column(s) by parallel flow tubes, and thus the multi-channel CCC apparatus can achieve simultaneously two or more independent chromatographic processes. Furthermore, a high-throughput CCC fractionation method for natural products has been developed by a combination of a new three-channel CCC apparatus and conventional parallel chromatographic devices including pumps, sample injectors, effluent detectors and collectors, and its performance has been displayed on the fractionation of ethyl acetate extracts of three natural materials Solidago canadensis, Suillus placidus, and Trichosanthes kirilowii, which are found to be potent cytotoxic to tumor cell lines in the course of screening the antitumor candidates. By combination of biological screening programs and preparative high-performance liquid chromatography (HPLC) purification, 22.8 mg 6 beta-angeloyloxykolavenic acid and 29.4 mg 6 beta-tigloyloxykolavenic acid for S. canadensis, 25.3mg suillin for S. placidus, and 6.8 mg 23,24-dihydrocucurbitacin B for T. Kirilowii as their major cytotoxic principles were isolated from each 1000 mg crude ethyl acetate extract. Their chemical structures were characterized by electrospray ionization mass spectrometry, one- and two-dimensional nuclear magnetic resonance. The overall results indicate the multi-channel CCC is very useful for high-throughput fractionation of natural products for drug discovery in spite of the solvent balancing requirement and the lower resolution of the shorter CCC columns.

Joint image reconstruction method with correlative multi-channel prior for x-ray spectral computed tomography

DEFF Research Database (Denmark)

Kazantsev, Daniil; Jørgensen, Jakob Sauer; Andersen, Martin S

2018-01-01

peaks. The acquired energy-binned data, however, suffer from low signal-to-noise ratio, acquisition artifacts, and frequently angular undersampled conditions. New regularized iterative reconstruction methods have the potential to produce higher quality images and since energy channels are mutually...... to encourage joint smoothing directions. In particular, the method selects reference channels from which to propagate structure in an adaptive and stochastic way while preferring channels with a high data signal-to-noise ratio. The method is compared with current state-of-the-art multi-channel reconstruction...

Transport of long-pulse relativistic electron beams in preformed plasma channels in the ion focus regime

International Nuclear Information System (INIS)

Miller, J.D.

1989-01-01

Experiments have been performed demonstrating efficient transport of long-pulse (380 ns), high-current (200 A), relativistic electron beams (REBs) in preformed plasma channels in the ion focus regime (IFR). Plasma channels were created by low-energy ( e , and channel ion mass, in agreement with theoretical values predicted for the ion hose instability. Microwave emission has also been observed indicative of REB-plasma electron two-stream instability. Plasma channel density measurements indicate that the two-stream instability can become dominant for measured f e values slightly above unity. The author has introduced a theoretical analysis for high-current REB transport and modulation in axially periodic IFR plasma channels. Analytic expression for the electric field are found for the case of a cosine modulation of the channel ion density. Two different types of channels are considered: (i) periodic beam-induced ionization channels, and (ii) periodic plasma slab channels created by an external source. Analytical conditions are derived for the matched radius of the electron beam and for approximate beam envelope motion using a 'smooth' approximation. Numerical solutions to the envelope equation show that by changing the wavelength or the amplitude of the space-charge neutralization fraction of the ion channel density modulation, the beam can be made to focus and diverge, or to undergo stable, modulated transport

On a multi-channel transportation loss system with controlled input and controlled service

Directory of Open Access Journals (Sweden)

Jewgeni Dshalalow

1987-01-01

Full Text Available A multi-channel loss queueing system is investigated. The input stream is a controlled point process. The service in each of m parallel channels depends on the state of the system at certain moments of time when input and service may be controlled. To obtain explicitly the limiting distribution of the main process (Zt (the number of busy channels in equilibrium, an auxiliary three dimensional process with two additional components (one of them is a semi-Markov process is treated as semi-regenerative process. An optimization problem is discussed. Simple expressions for an objective function are derived.

Electro-optic tunable multi-channel filter in two-dimensional ferroelectric photonic crystals

International Nuclear Information System (INIS)

Fu, Yulan; Zhang, Jiaxiang; Hu, Xiaoyong; Gong, Qihuang

2010-01-01

An electro-optic tunable multi-channel filter is presented, which is based on a two-dimensional ferroelectric photonic crystal made of barium titanate. The filtering properties of the photonic crystal filter can be tuned by an applied voltage or by adjusting the structural parameters. The channel shifts about 30 nm under excitation of an applied voltage of 54.8 V. The influences of the structural disorders caused by the perturbations in the radius or the position of air holes on the filtering properties are also analyzed

Asymptotically exact solution of the multi-channel resonant-level model

International Nuclear Information System (INIS)

Zhang Guangming; Su Zhaobin; Yu Lu.

1994-01-01

An asymptotically exact partition function of the multi-channel resonant-level model is obtained through Tomonaga-Luttinger bosonization. A Fermi-liquid vs. non-Fermi-liquid transition, resulting from a competition between the Kondo and X-ray edge physics, is elucidated explicitly via the renormalization group theory. In the strong-coupling limit, the model is renormalized to the Toulouse limit. (author). 20 refs, 1 fig

The software for the USB-based multi-channel analyzer system

International Nuclear Information System (INIS)

Zhou Tong; Wei Yixiang

2002-01-01

A new type of multi-channel analyzer system is introduced, which takes advantage of Universal Serial Bus to communicate with computer and gets the merit of fast speed, universality and Plug and Play. The authors discussed the framework of the system, primary functions, display of spectrum date and the way of communication with hardware. The environment of the program is Visual Basic 6.0

Automatic extraction and processing of small RNAs on a multi-well/multi-channel (M&M) chip.

Science.gov (United States)

Zhong, Runtao; Flack, Kenneth; Zhong, Wenwan

2012-12-07

The study of the regulatory roles in small RNAs can be accelerated by techniques that permit simple, low-cost, and rapid extraction of small RNAs from a small number of cells. In order to ensure highly specific and sensitive detection, the extracted RNAs should be free of the background nucleic acids and present stably in a small volume. To meet these criteria, we designed a multi-well/multi-channel (M&M) chip to carry out automatic and selective isolation of small RNAs via solid-phase extraction (SPE), followed by reverse-transcription (RT) to convert them to the more stable cDNAs in a final volume of 2 μL. Droplets containing buffers for RNA binding, washing, and elution were trapped in microwells, which were connected by one channel, and suspended in mineral oil. The silica magnetic particles (SMPs) for SPE were moved along the channel from well to well, i.e. in between droplets, by a fixed magnet and a translation stage, allowing the nucleic acid fragments to bind to the SMPs, be washed, and then be eluted for RT reaction within 15 minutes. RNAs shorter than 63 nt were selectively enriched from cell lysates, with recovery comparable to that of a commercial kit. Physical separation of the droplets on our M&M chip allowed the usage of multiple channels for parallel processing of multiple samples. It also permitted smooth integration with on-chip RT-PCR, which simultaneously detected the target microRNA, mir-191, expressed in fewer than 10 cancer cells. Our results have demonstrated that the M&M chip device is a valuable and cost-saving platform for studying small RNA expression patterns in a limited number of cells with reasonable sample throughput.

Multi-Pulse Excitation for Underwater Analysis of Copper-Based Alloys Using a Novel Remote Laser-Induced Breakdown Spectroscopy (LIBS) System.

Science.gov (United States)

Guirado, Salvador; Fortes, Francisco J; Laserna, J Javier

2016-04-01

In this work, the use of multi-pulse excitation has been evaluated as an effective solution to mitigate the preferential ablation of the most volatile elements, namely Sn, Pb, and Zn, observed during laser-induced breakdown spectroscopy (LIBS) analysis of copper-based alloys. The novel remote LIBS prototype used in this experiments featured both single-pulse (SP-LIBS) and multi-pulse excitation (MP-LIBS). The remote instrument is capable of performing chemical analysis of submersed materials up to a depth of 50 m. Laser-induced breakdown spectroscopy analysis was performed at air pressure settings simulating the conditions during a real subsea analysis. A set of five certified bronze standards with variable concentration of Cu, As, Sn, Pb, and Zn were used. In SP-LIBS, signal emission is strongly sensitive to ambient pressure. In this case, fractionation effect was observed. Multi-pulse excitation circumvents the effect of pressure over the quantitative analysis, thus avoiding the fractionation phenomena observed in single pulse LIBS. The use of copper as internal standard minimizes matrix effects and discrepancies due to variation in ablated mass. © The Author(s) 2016.

Multi-Instrument Investigation of Ionospheric Flow Channels and Their Impact on the Ionosphere and Thermosphere during Geomagnetic Storms

Science.gov (United States)

2017-12-29

AFRL-AFOSR-JP-TR-2018-0009 Multi-instrument investigation of ionospheric flow channels and their impact on the ionosphere and thermosphere during...SUBTITLE Multi-instrument investigation of ionospheric flow channels and their impact on the ionosphere and thermosphere during geomagnetic storms 5a...Experiment) and GOCE (Gravity field and steady- state Ocean Circulation Explorer) satellite data. We also created a series of computer algorithms to

A method to reduce the suppression of relevant pulses in pulse weight discriminators

International Nuclear Information System (INIS)

Schwartz, P.

1975-01-01

The pulse height analyzer is used, for instance, with proportional counters. Pulses are broken down into amplitude ranges in accordance with their maximum amplitudes. In pulse height analyzers with real time analog-digital conversion only one deadtime is needed for the respective range selected. For this purpose, all discriminator thresholds of the amplitude stores connected parallel are actuated as an input pulse arrives. The leading edges of the discriminator signals set the amplitude range flip-flop. Only the flip-flop circuit of the maximum amplitude range reached remains set whilst all the others are erased. The trailing edge of the discriminator signals actuates the evaluation of the information stored by the flip-flop circuit selected. It triggers a pulse extender and resets the flip-flop selected. Therefore, only the amplitude range selected needs a deadtime. The pulse extender in addition reduces the processing time of the analyzer by the output pulse length. The characteristic used for the trailing edge is the backward count of the real time analog-digital converter. (DG/RF) [de

A multi-channel data acquisition system with high resolution based on microcomputer

International Nuclear Information System (INIS)

An Qi; Wang Yanfang; Xing Tao

1995-01-01

The paper introduces the principle of a multi-channel data acquisition system with high resolution based on the microcomputer.The system consists of five parts.They are analog-to-digital converter, data buffer area, trigger logic circuit, control circuit, and digital-to-analog converter

Compact and cost-effective multi-channel optical spectrometer for fine FBG sensing in IoT technology

Science.gov (United States)

Konishi, Tsuyoshi; Yamasaki, Yu

2018-02-01

Optical fiber sensor networks have attracted much attention in IoT technology and a fiber Bragg grating is one of key sensor devices there because of their advantages in a high affinity for optical fiber networks, compactness, immunity to electromagnetic interference and so on. Nevertheless, its sensitivity is not always satisfactory so as to be usable together with widespread cost-effective multi-channel spectrometers. In this paper, we introduce a new cost-effective approach for a portable multi-channel spectrometer with high spectral resolution and demonstrates some preliminary experimental results for fine FBG sensing.

Multi channel analyzer system addible to personal computer

International Nuclear Information System (INIS)

Ramirez J, F.J.; Garcia R, R.; Ramirez N, R.; Torres B, M.A.

1996-01-01

It has been developed a Multichannel analyzer system which was added to personal computer of 4096 channels for its use, in nuclear radiations matters, such as X-ray fluorescence analysis, Neutron activation analysis, etc. in that is interesting to know the radiation energy distribution. This system has three modules; a Digital analogical converter of 12 bits, fast (total conversion time of 6 μ s) that use a successive approximation technique with linearity correction by the gliding rule method. A digital card with microprocessor that is useful as an interface with the computer for the acquisition, data storage and the process control. A computer program with extensive use of graphics, friendly with the user in order to facilitate its utilization, also with the option to find peaks, an expansion of an interesting area, information storage in compatible format with spectra analysis programs, etc. Twenty five units of this system have been constructed which all of they were distributed to the ARCAL Member countries and the other 10 units were distributed in the National Institute of Nuclear Research. On the other hand, it has been able to find other applications where the information can be converted to pulses and the interest variable is represented by the pulse amplitude. (Author)

Multi - pulse tea CO2 laser beam interaction with the TiN thin films

International Nuclear Information System (INIS)

Gakovic, B.; Trtica, M.; Nenadovic, T.; Pavlicevic, B.

1998-01-01

The interaction of various types of energetic beams including a laser beam with the high-hardness coatings is of great fundamental and technological interest. The Nd:YAG, excimer and CO 2 are frequently used laser beams for this purpose. The interaction of a laser beam with low thickness coatings, deposited on austenitic stainless steel, is insufficiently known in the literature. Titanium nitride (TiN) possess the excellent physico-chemical characteristics. For this reason TiN films/coatings are widely used. The purpose of this article is a consideration of the effect of TEA C0 2 laser radiation on the TiN film deposited on austenitic stainless steel substrate (AISI 316). Investigation of TiN morphological changes, after multipulse laser irradiation, shown dependence on laser fluence, number of laser pulses and the laser pulse shape. Subsequently fast heating and cooling during multi-pulse laser bombardment cause the grain growth of TiN layer. Both laser pulses (pulses with tail and tail-free pulses) produced periodical wave like structure on polished substrate material. Periodicity is observed also on AISI 316 protected with TiN layer, but only with laser pulse with tail. (author)

Salt Plug Formation Caused by Decreased River Discharge in a Multi-channel Estuary

OpenAIRE

Shaha, Dinesh Chandra; Cho, Yang-Ki

2016-01-01

Freshwater input to estuaries may be greatly altered by the river barrages required to meet human needs for drinking water and irrigation and prevent salt water intrusion. Prior studies have examined the salt plugs associated with evaporation and salt outwelling from tidal salt flats in single-channel estuaries. In this work, we discovered a new type of salt plug formation in the multi-channel Pasur River Estuary (PRE) caused by decreasing river discharges resulting from an upstream barrage. ...

On the relationship between multi-channel envelope and temporal fine structure

DEFF Research Database (Denmark)

Søndergaard, Peter Lempel; Decorsiere, Remi Julien Blaise; Dau, Torsten

2011-01-01

The envelope of a signal is broadly defined as the slow changes in time of the signal, where as the temporal fine structure (TFS) are the fast changes in time, i.e. the carrier wave(s) of the signal. The focus of this paper is on envelope and TFS in multi-channel systems. We discuss the differenc...

Exploiting the opportunities of Internet and multi-channel pricing : An exploratory research

NARCIS (Netherlands)

Sotgiu, Francesca; Ancarani, Fabio

2004-01-01

Smart firms are not worried about the impact of the Internet on pricing, but realise that they have the unique opportunity to exploit new options and improve their marketing performance. Multi-channel pricing is one of the most interesting opportunities firms can exploit in the digital economy.

Experimental study of the effect of Nd:YAG laser on dental hard tissues: comparison between multi-pulse and free-generation emission code

International Nuclear Information System (INIS)

Carballosa Amor, A.; Tellez Jimenez, H.; Ponce Flores, E.; Flores Reyes, T.

2016-01-01

The aim of this study is to compare and contrast the morphological changes on dental hard tissue when irradiated with a Nd: YAG laser both on multi-pulse mode, with a Q: Switch of Cr: YAG passive, and on free generation mode. The experimental sample consisted of 6 healthy third molars which were divided equally and randomly between the two emission methods. The depths of each perforation were measured by optical coherence tomography (OCT). It was noted that, despite being less energy in the multi-pulse mode, the first three shots in this achieved deeper cavities than the ones on the free generation mode. Also, less damage to surrounding tissue were obtained on multi-pulse mode. (Author)

Multi codes and multi-scale analysis for void fraction prediction in hot channel for VVER-1000/V392

International Nuclear Information System (INIS)

Hoang Minh Giang; Hoang Tan Hung; Nguyen Huu Tiep

2015-01-01

Recently, an approach of multi codes and multi-scale analysis is widely applied to study core thermal hydraulic behavior such as void fraction prediction. Better results are achieved by using multi codes or coupling codes such as PARCS and RELAP5. The advantage of multi-scale analysis is zooming of the interested part in the simulated domain for detail investigation. Therefore, in this study, the multi codes between MCNP5, RELAP5, CTF and also the multi-scale analysis based RELAP5 and CTF are applied to investigate void fraction in hot channel of VVER-1000/V392 reactor. Since VVER-1000/V392 reactor is a typical advanced reactor that can be considered as the base to develop later VVER-1200 reactor, then understanding core behavior in transient conditions is necessary in order to investigate VVER technology. It is shown that the item of near wall boiling, Γ w in RELAP5 proposed by Lahey mechanistic method may not give enough accuracy of void fraction prediction as smaller scale code as CTF. (author)

Multi-channel Waveform Sampling ASIC for radiation detection and measurement

International Nuclear Information System (INIS)

Shimazoe, K.; Takahashi, H.; Yeom, J.Y.; Furumiya, T.; Ohi, J.

2013-01-01

We have designed and fabricated a 16-channel Waveform Sampling ASIC for radiation detection and measurement. Waveform sampling is very important for the pulse shape analysis and discrimination, which is often used in radiation detection to discriminate different radiations such as alpha, beta and gamma rays. One channel of the fabricated ASIC consists of a charge-sensitive preamplifier, a VGA (Variable Gain Amplifier), an ADC (Analog to Digital Converter) and digital circuits. The preamplifier converts the current signal to the voltage signal, and the VGA amplifies the signal to appropriate level for the ADC. The ADC was designed to digitize the waveform with a frequency of 100 MHz and a resolution of 6bits. Digital circuits consist of a free-running ADC and a multiplexer which were designed to convert a digitized 100 MHz/6bit signal to a 200 MHz/3bit one, which is effective for the reduction of the number and for the achievement of the high integration in one chip. This chip was designed and fabricated with 0.35 μm CMOS technology by ROHM and the size of the ASIC is 4.9 mm by 4.9 mm. The design concept and some experimental results are shown in this paper. -- Highlights: ► Waveform sampling (WS) ASIC is newly developed for pulse shape discrimination. ► WS ASIC can be used for radiation measurement and discrimination. ► WS ASIC is fabricated by submicron CMOS technology for 5 mm × 5 mm area. ► WS ASIC achieves high integration and can be used in very limited space

Optimization of multi-channel neutron focusing guides for extreme sample environments

International Nuclear Information System (INIS)

Di Julio, D D; Lelièvre-Berna, E; Andersen, K H; Bentley, P M; Courtois, P

2014-01-01

In this work, we present and discuss simulation results for the design of multichannel neutron focusing guides for extreme sample environments. A single focusing guide consists of any number of supermirror-coated curved outer channels surrounding a central channel. Furthermore, a guide is separated into two sections in order to allow for extension into a sample environment. The performance of a guide is evaluated through a Monte-Carlo ray tracing simulation which is further coupled to an optimization algorithm in order to find the best possible guide for a given situation. A number of population-based algorithms have been investigated for this purpose. These include particle-swarm optimization, artificial bee colony, and differential evolution. The performance of each algorithm and preliminary results of the design of a multi-channel neutron focusing guide using these methods are described. We found that a three-channel focusing guide offered the best performance, with a gain factor of 2.4 compared to no focusing guide, for the design scenario investigated in this work.

Multi-frequency accelerating strategy for the contrast source inversion method of ultrasound waveform tomography using pulse data

Science.gov (United States)

Lin, Hongxiang; Azuma, Takashi; Qu, Xiaolei; Takagi, Shu

2017-03-01

In this work, we construct a multi-frequency accelerating strategy for the contrast source inversion (CSI) method using pulse data in the time domain. CSI is a frequency-domain inversion method for ultrasound waveform tomography that does not require the forward solver through the process of reconstruction. Several prior researches show that the CSI method has a good performance of convergence and accuracy in the low-center-frequency situation. In contrast, utilizing the high-center-frequency data leads to a high-resolution reconstruction but slow convergence on large numbers of grid. Our objective is to take full advantage of all low frequency components from pulse data with the high-center-frequency data measured by the diagnostic device. First we process the raw data in the frequency domain. Then multi-frequency accelerating strategy helps restart CSI in the current frequency using the last iteration result obtained from the lower frequency component. The merit of multi- frequency accelerating strategy is that computational burden decreases at the first few iterations. Because the low frequency component of dataset computes on the coarse grid with assuming a fixed number of points per wavelength. In the numerical test, the pulse data were generated by the K-wave simulator and have been processed to meet the computation of the CSI method. We investigate the performance of the multi-frequency and single-frequency reconstructions and conclude that the multi-frequency accelerating strategy significantly enhances the quality of the reconstructed image and simultaneously reduces the average computational time for any iteration step.

Plasma channels for electron beam transport

International Nuclear Information System (INIS)

Schneider, R.F.; Smith, J.R.; Moffatt, M.E.; Nguyen, K.T.; Uhm, H.S.

1988-01-01

In recent years, there has been much interest in transport of intense relativistic electron beams using plasma channels. These channels are formed by either: ionization of an organic gas by UV photoionization or electron impact ionization of a low pressure gas utilizing a low energy (typically several hundred volts) electron gun. The second method is discussed here. As their electron gun, the authors used a 12 volt lightbulb filament which is biased to -400 volts with respect to the grounded 15 cm diameter drift tube. The electrons emitted from the filament are confined by an axial magnetic field of --100 Gauss to create a plasma channel which is less than 1 cm in radius. The channel density has been determined with Langmuir probes and the resulting line densities were found to be 10 11 to 10 12 per cm. When a multi-kiloamp electron beam is injected onto this channel, the beam space charge will eject the plasma electrons leaving the ions behind to charge neutralize the electron beam, hence allowing the beam to propagate. In this work, the authors performed experimental studies on the dynamics of the plasma channel. These include Langmuir probe measurements of a steady state (DC) channel, as well as time-resolved Langmuir probe studies of pulsed channels. In addition they performed experimental studies of beam propagation in these plasma channels. Specifically, they observed the behavior of current transport in these channels. Detailed results of beam transport and channel studies are presented

Time-correlated pulse-height measurements of low-multiplying nuclear materials

Energy Technology Data Exchange (ETDEWEB)

Miller, E.C., E-mail: ericcm@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Dolan, J.L.; Clarke, S.D.; Pozzi, S.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI (United States); Tomanin, A.; Peerani, P. [European Commission EC-JRC-IPSC, Ispra (Italy); Marleau, P. [Sandia National Laboratories, Livermore, CA (United States); Mattingly, J.K. [North Carolina State University, Raleigh, NC (United States)

2013-11-21

Methods for the determination of the subcritical neutron multiplication of nuclear materials are of interest in the field of nuclear nonproliferation and safeguards. A series of measurements were performed at the Joint Research Center facility in Ispra, Italy to investigate the possibility of using a time-correlated pulse-height (TCPH) analysis to estimate the sub-critical multiplication of nuclear material. The objective of the measurements was to evaluate the effectiveness of this technique, and to benchmark the simulation capabilities of MCNPX-PoliMi/MPPost. In this campaign, two low-multiplication samples were measured: a 1-kg mixed oxide (MOX) powder sample and several low-mass plutonium–gallium (PuGa) disks. The measured results demonstrated that the sensitivity of the TCPH technique could not clearly distinguish samples with very-low levels of multiplication. However, the simulated TCPH distributions agree well with the measured data, within 12% for all cases, validating the simulation capabilities of MCNPX-PoliMi/MPPost. To investigate the potential of the TCPH method for identifying high-multiplication samples, the validated MCNPX-PoliMi/MPPost codes were used to simulate sources of higher multiplications. Lastly, a characterization metric, the cumulative region integral (CRI), was introduced to estimate the level of multiplication in a source. However, this response was shown to be insensitive over the range of multiplications of interest. -- Highlights: •Present results of measurements of MOX fuel and PuGa disks. •Compared measurement results to simulations performed using MCNPX-Polimi and MPPost. •Investigated using correlated γ–n pairs to determine the multiplication of a system.

Pilot-Assisted Channel Estimation for Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

Science.gov (United States)

Shima, Tomoyuki; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of time-domain spreading and orthogonal frequency division multiplexing (OFDM). In orthogonal MC DS-CDMA, the frequency diversity gain can be obtained by applying frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion to a block of OFDM symbols and can improve the bit error rate (BER) performance in a severe frequency-selective fading channel. FDE requires an accurate estimate of the channel gain. The channel gain can be estimated by removing the pilot modulation in the frequency domain. In this paper, we propose a pilot-assisted channel estimation suitable for orthogonal MC DS-CDMA with FDE and evaluate, by computer simulation, the BER performance in a frequency-selective Rayleigh fading channel.

Multi-pulse drug delivery from a resorbable polymeric microchip device

Science.gov (United States)

Grayson, Amy C. Richards; Choi, Insung S.; Tyler, Betty M.; Wang, Paul P.; Brem, Henry; Cima, Michael J.; Langer, Robert

2003-11-01

Controlled-release drug delivery systems have many applications, including treatments for hormone deficiencies and chronic pain. A biodegradable device that could provide multi-dose drug delivery would be advantageous for long-term treatment of conditions requiring pulsatile drug release. In this work, biodegradable polymeric microchips were fabricated that released four pulses of radiolabelled dextran, human growth hormone or heparin in vitro. Heparin that was released over 142 days retained on average 96 +/- 12% of its bioactivity. The microchips were 1.2 cm in diameter, 480-560 μm thick and had 36 reservoirs that could each be filled with a different chemical. The devices were fabricated from poly(L-lactic acid) and had poly(D,L-lactic-co-glycolic acid) membranes of different molecular masses covering the reservoirs. A drug delivery system can be designed with the potential to release pulses of different drugs at intervals after implantation in a patient by using different molecular masses or materials for the membrane.

Miniaturized multi channel infrared optical gas sensor system

Science.gov (United States)

Wöllenstein, Jürgen; Eberhardt, Andre; Rademacher, Sven; Schmitt, Katrin

2011-06-01

Infrared spectroscopy uses the characteristic absorption of the molecules in the mid infrared and allows the determination of the gases and their concentration. Especially by the absorption at longer wavelengths between 8 μm and 12 μm, the so called "fingerprint" region, the molecules can be measured with highest selectivity. We present an infrared optical filter photometer for the analytical determination of trace gases in the air. The challenge in developing the filter photometer was the construction of a multi-channel system using a novel filter wheel concept - which acts as a chopper too- in order to measure simultaneously four gases: carbon monoxide, carbon dioxide, methane and ammonia. The system consists of a broadband infrared emitter, a long path cell with 1.7m optical path length, a filter wheel and analogue and digital signal processing. Multi channel filter photometers normally need one filter and one detector per target gas. There are small detection units with one, two or more detectors with integrated filters available on the market. One filter is normally used as reference at a wavelength without any cross-sensitivities to possible interfering gases (e.g. at 3.95 μm is an "atmospheric window" - a small spectral band without absorbing gases in the atmosphere). The advantage of a filter-wheel set-up is that a single IR-detector can be used, which reduces the signal drift enormously. Pyroelectric and thermopile detectors are often integrated in these kinds of spectrometers. For both detector types a modulation of the light is required and can be done - without an additional chopper - with the filter wheel.

Stochastic geometry model for multi-channel fog radio access networks

KAUST Repository

Emara, Mostafa

2017-06-29

Cache-enabled base station (BS) densification, denoted as a fog radio access network (F-RAN), is foreseen as a key component of 5G cellular networks. F-RAN enables storing popular files at the network edge (i.e., BS caches), which empowers local communication and alleviates traffic congestions at the core/backhaul network. The hitting probability, which is the probability of successfully transmitting popular files request from the network edge, is a fundamental key performance indicator (KPI) for F-RAN. This paper develops a scheduling aware mathematical framework, based on stochastic geometry, to characterize the hitting probability of F-RAN in a multi-channel environment. To this end, we assess and compare the performance of two caching distribution schemes, namely, uniform caching and Zipf caching. The numerical results show that the commonly used single channel environment leads to pessimistic assessment for the hitting probability of F-RAN. Furthermore, the numerical results manifest the superiority of the Zipf caching scheme and quantify the hitting probability gains in terms of the number of channels and cache size.

Superpixel-based segmentation of muscle fibers in multi-channel microscopy.

Science.gov (United States)

Nguyen, Binh P; Heemskerk, Hans; So, Peter T C; Tucker-Kellogg, Lisa

2016-12-05

Confetti fluorescence and other multi-color genetic labelling strategies are useful for observing stem cell regeneration and for other problems of cell lineage tracing. One difficulty of such strategies is segmenting the cell boundaries, which is a very different problem from segmenting color images from the real world. This paper addresses the difficulties and presents a superpixel-based framework for segmentation of regenerated muscle fibers in mice. We propose to integrate an edge detector into a superpixel algorithm and customize the method for multi-channel images. The enhanced superpixel method outperforms the original and another advanced superpixel algorithm in terms of both boundary recall and under-segmentation error. Our framework was applied to cross-section and lateral section images of regenerated muscle fibers from confetti-fluorescent mice. Compared with "ground-truth" segmentations, our framework yielded median Dice similarity coefficients of 0.92 and higher. Our segmentation framework is flexible and provides very good segmentations of multi-color muscle fibers. We anticipate our methods will be useful for segmenting a variety of tissues in confetti fluorecent mice and in mice with similar multi-color labels.

Coupling of laser energy into plasma channels

International Nuclear Information System (INIS)

Dimitrov, D. A.; Giacone, R. E.; Bruhwiler, D. L.; Busby, R.; Cary, J. R.; Geddes, C. G. R.; Esarey, E.; Leemans, W. P.

2007-01-01

Diffractive spreading of a laser pulse imposes severe limitations on the acceleration length and maximum electron energy in the laser wake field accelerator (LWFA). Optical guiding of a laser pulse via plasma channels can extend the laser-plasma interaction distance over many Rayleigh lengths. Energy efficient coupling of laser pulses into and through plasma channels is very important for optimal LWFA performance. Results from simulation parameter studies on channel guiding using the particle-in-cell (PIC) code VORPAL [C. Nieter and J. R. Cary, J. Comput. Phys. 196, 448 (2004)] are presented and discussed. The effects that density ramp length and the position of the laser pulse focus have on coupling into channels are considered. Moreover, the effect of laser energy leakage out of the channel domain and the effects of tunneling ionization of a neutral gas on the guided laser pulse are also investigated. Power spectral diagnostics were developed and used to separate pump depletion from energy leakage. The results of these simulations show that increasing the density ramp length decreases the efficiency of coupling a laser pulse to a channel and increases the energy loss when the pulse is vacuum focused at the channel entrance. Then, large spot size oscillations result in increased energy leakage. To further analyze the coupling, a differential equation is derived for the laser spot size evolution in the plasma density ramp and channel profiles are simulated. From the numerical solution of this equation, the optimal spot size and location for coupling into a plasma channel with a density ramp are determined. This result is confirmed by the PIC simulations. They show that specifying a vacuum focus location of the pulse in front of the top of the density ramp leads to an actual focus at the top of the ramp due to plasma focusing, resulting in reduced spot size oscillations. In this case, the leakage is significantly reduced and is negligibly affected by ramp length

Ergodic channel capacity of spatial correlated multiple-input multiple-output free space optical links using multipulse pulse-position modulation

Science.gov (United States)

Wang, Huiqin; Wang, Xue; Cao, Minghua

2017-02-01

The spatial correlation extensively exists in the multiple-input multiple-output (MIMO) free space optical (FSO) communication systems due to the channel fading and the antenna space limitation. Wilkinson's method was utilized to investigate the impact of spatial correlation on the MIMO FSO communication system employing multipulse pulse-position modulation. Simulation results show that the existence of spatial correlation reduces the ergodic channel capacity, and the reception diversity is more competent to resist this kind of performance degradation.

Comment on "Defocusing complex short-pulse equation and its multi-dark-soliton solution"

Science.gov (United States)

Youssoufa, Saliou; Kuetche, Victor K.; Kofane, Timoleon C.

2017-08-01

In their recent paper, Feng et al. [Phys. Rev. E 93, 052227 (2016), 10.1103/PhysRevE.93.052227] proposed a complex short-pulse equation of both focusing and defocusing types. They studied in detail the defocusing case and derived its multi-dark-soliton solutions. Nonetheless, from a physical viewpoint in order to better and deeply understand their genuine implications, we find it useful to provide a real and proper background for the derivation of the previous evolution system while showing that the expression of the nonlinear electric polarization the above authors used in their scheme is not suitable for getting the defocusing complex short-pulse equation.

Automated Filtering of Common Mode Artifacts in Multi-Channel Physiological Recordings

Science.gov (United States)

Kelly, John W.; Siewiorek, Daniel P.; Smailagic, Asim; Wang, Wei

2014-01-01

The removal of spatially correlated noise is an important step in processing multi-channel recordings. Here, a technique termed the adaptive common average reference (ACAR) is presented as an effective and simple method for removing this noise. The ACAR is based on a combination of the well-known common average reference (CAR) and an adaptive noise canceling (ANC) filter. In a convergent process, the CAR provides a reference to an ANC filter, which in turn provides feedback to enhance the CAR. This method was effective on both simulated and real data, outperforming the standard CAR when the amplitude or polarity of the noise changes across channels. In many cases the ACAR even outperformed independent component analysis (ICA). On 16 channels of simulated data the ACAR was able to attenuate up to approximately 290 dB of noise and could improve signal quality if the original SNR was as high as 5 dB. With an original SNR of 0 dB, the ACAR improved signal quality with only two data channels and performance improved as the number of channels increased. It also performed well under many different conditions for the structure of the noise and signals. Analysis of contaminated electrocorticographic (ECoG) recordings further showed the effectiveness of the ACAR. PMID:23708770

Experimental test results of multi-channel test rig of T1 test section, 5

International Nuclear Information System (INIS)

Hino, Ryutaro; Takase, Kazuyuki; Miyamoto, Yoshiaki

1990-09-01

Channel blockage test on a fuel column of the high temperature engineering test reactor (HTTR) has been performed under the helium gas atmosphere at a high temperature and a high pressure in order to obtain safety data on flow rate and temperature distributions in the fuel column with the multi-channel test rig of the fuel stack test section (T 1 ) in HENDEL. In the test, one of 12 fuel channels was blockaded to 90% of flow area at the channel inlet. Experimental results showed that the helium gas flow rate in the blockaded channel was 28%∼33% lower than the average flow rate for Reynolds number from 2300 to 14000 in isothermal flow. When simulated fuel rods were heated, the flow rate in the blockaded channel did not decrease down in comparison with the isothermal flow. This is due to that the heat generated in the fuel rods conducts to the other fuel channels in graphite fuel blocks, so that accelerated pressure losses in the fuel channels change with helium gas temperatures. (author)

Adaptive noise canceling of electrocardiogram artifacts in single channel electroencephalogram.

Science.gov (United States)

Cho, Sung Pil; Song, Mi Hye; Park, Young Cheol; Choi, Ho Seon; Lee, Kyoung Joung

2007-01-01

A new method for estimating and eliminating electrocardiogram (ECG) artifacts from single channel scalp electroencephalogram (EEG) is proposed. The proposed method consists of emphasis of QRS complex from EEG using least squares acceleration (LSA) filter, generation of synchronized pulse with R-peak and ECG artifacts estimation and elimination using adaptive filter. The performance of the proposed method was evaluated using simulated and real EEG recordings, we found that the ECG artifacts were successfully estimated and eliminated in comparison with the conventional multi-channel techniques, which are independent component analysis (ICA) and ensemble average (EA) method. From this we can conclude that the proposed method is useful for the detecting and eliminating the ECG artifacts from single channel EEG and simple to use for ambulatory/portable EEG monitoring system.

Multi parametric system for the acquisition and processing of nuclear data on a personal computer

International Nuclear Information System (INIS)

Toledo Acosta, R. B.; Osorio Deliz, J. F.; Arista Romeu, E.; Perez Sanchez, R.; Lopez Torres, E.

1997-01-01

A four-parameter Multi parametric System for the acquisition and processing of nuclear data is described. It is characterized for its flexibility and relatively low cost, also guaranteeing a high acquisition capacity. The system allows to be utilized in a multi parametric manner, in pulse height analysis or in any combination of both for parameter. The hardware and the software of the system are described. A general explanation of the operation and the characteristics of the system is offered. (author) [es

Dynamic pulse difference circuit

International Nuclear Information System (INIS)

Erickson, G.L.

1978-01-01

A digital electronic circuit of especial use for subtracting background activity pulses in gamma spectrometry is disclosed which comprises an up-down counter connected to count up with signal-channel pulses and to count down with background-channel pulses. A detector responsive to the count position of the up-down counter provides a signal when the up-down counter has completed one scaling sequence cycle of counts in the up direction. In an alternate embodiment, a detector responsive to the count position of the up-down counter provides a signal upon overflow of the counter

Osmosis and pervaporation in polyimide submicron microfluidic channel structures

NARCIS (Netherlands)

Eijkel, Jan C.T.; Bomer, Johan G.; van den Berg, Albert

2005-01-01

Osmosis and pervaporation of water through the roof of all-polyimide channels of 500 nm height is described. The phenomena cause both a liquid flow in the channels and a concentration change of dissolved salt. Both effects are amplified due to the thin channel roof and the small channel height.

Heating of multi-layered samples by a Nd: YAG pulsed laser

International Nuclear Information System (INIS)

Diniz Neto, O.O.

1998-01-01

In the work we examine the heating of multi-layered samples by a powerful Nd-YAG pulsed laser. The samples are made of two and three layers, conductor-isolator (Al-Al 2 O 3 ). conductor-conductor (Al-Ag: Al-Au) an conductor-conductor-conductor (Al-Au-Ag:Ag-Au-Al). The transient behaviour of the temperature distribution throughout the samples is computed. We carry out three dimensional model calculations for the heating process in which we consider not only the temperature dependence of the sample thermal and optical parameters but also the space and time characteristics of the laser beams as the heating source. We showed the influence of the substrate in the thermal profile, in space and time, and maximum temperature on the multi-layered samples. (Author) 11 refs

Take time to make time : What to consider when managing multi-channel sales systems with the objective to increase sales efficiency

OpenAIRE

ALM, RAGNAR; KYRÖNLAHTI, RUDY

2016-01-01

Traditional sales systems have been disrupted by technological developments. In order to  adapt, companies are changing the way they interact with their customers in business-to-business markets. In the last three decades, multi-channel strategies have spurred the proliferation of different sales channels and new ways of managing sales systems. The purpose of this research was to investigate what should be considered when managing multi-channel sales systems with the objective of increasing s...

Multiplex multivariate recurrence network from multi-channel signals for revealing oil-water spatial flow behavior.

Science.gov (United States)

Gao, Zhong-Ke; Dang, Wei-Dong; Yang, Yu-Xuan; Cai, Qing

2017-03-01

The exploration of the spatial dynamical flow behaviors of oil-water flows has attracted increasing interests on account of its challenging complexity and great significance. We first technically design a double-layer distributed-sector conductance sensor and systematically carry out oil-water flow experiments to capture the spatial flow information. Based on the well-established recurrence network theory, we develop a novel multiplex multivariate recurrence network (MMRN) to fully and comprehensively fuse our double-layer multi-channel signals. Then we derive the projection networks from the inferred MMRNs and exploit the average clustering coefficient and the spectral radius to quantitatively characterize the nonlinear recurrent behaviors related to the distinct flow patterns. We find that these two network measures are very sensitive to the change of flow states and the distributions of network measures enable to uncover the spatial dynamical flow behaviors underlying different oil-water flow patterns. Our method paves the way for efficiently analyzing multi-channel signals from multi-layer sensor measurement system.

Pulse-voltage fast generator

International Nuclear Information System (INIS)

Valeev, R.I.; Nikiforov, M.G.; Kharchenko, A.F.

1988-01-01

The design is described and the test results of a four-channel pulse-voltage generator with maximum output voltage 200 kV are presented. The measurement results of generator triggering time depending on the value and polarity of the triggering voltage pulse for different triggering circuits are presented. The tests have shown stable triggering of all four channels of the generator in the range up to 40 % from selfbreakdown voltage. The generator triggering delay in the given range is <25 ns, asynchronism in channel triggering is <±1 ns

Multi-channel up-conversion infrared spectrometer and method of detecting a spectral distribution of light

DEFF Research Database (Denmark)

2015-01-01

A multi-channel infrared spectrometer for detecting an infrared spectrum of light received from an object. The spectrometer comprises a wavelength converter system comprising a nonlinear material and having an input side and an output side. The wavelength converter system comprises at least a first...... on the first side into light in a second output wavelength range output on the second side. The spectrometer further comprises a demultiplexer configured for demultiplexing light in the first up-conversion channel and light in the second up-conversion channel. The demultiplexer is located on the first side...

Four-channel delay generator model 5740

International Nuclear Information System (INIS)

Baumatz, D.; Milner, M.

1978-01-01

The 4-channel delay generator model 5740 generates 4-pulse groups in independent channels. The device offers the possibility of controlling both the time intervals between the pulses of a group and the rate of generation of groups

Opacity annotation of diffuse lung diseases using deep convolutional neural network with multi-channel information

Science.gov (United States)

Mabu, Shingo; Kido, Shoji; Hashimoto, Noriaki; Hirano, Yasushi; Kuremoto, Takashi

2018-02-01

This research proposes a multi-channel deep convolutional neural network (DCNN) for computer-aided diagnosis (CAD) that classifies normal and abnormal opacities of diffuse lung diseases in Computed Tomography (CT) images. Because CT images are gray scale, DCNN usually uses one channel for inputting image data. On the other hand, this research uses multi-channel DCNN where each channel corresponds to the original raw image or the images transformed by some preprocessing techniques. In fact, the information obtained only from raw images is limited and some conventional research suggested that preprocessing of images contributes to improving the classification accuracy. Thus, the combination of the original and preprocessed images is expected to show higher accuracy. The proposed method realizes region of interest (ROI)-based opacity annotation. We used lung CT images taken in Yamaguchi University Hospital, Japan, and they are divided into 32 × 32 ROI images. The ROIs contain six kinds of opacities: consolidation, ground-glass opacity (GGO), emphysema, honeycombing, nodular, and normal. The aim of the proposed method is to classify each ROI into one of the six opacities (classes). The DCNN structure is based on VGG network that secured the first and second places in ImageNet ILSVRC-2014. From the experimental results, the classification accuracy of the proposed method was better than the conventional method with single channel, and there was a significant difference between them.

Evaluation of K x-ray escape and crosstalk in CdTe detectors and multi-channel detectors

International Nuclear Information System (INIS)

Ohtsuchi, Tetsuro; Ohmori, Koichi; Tsutsui, Hiroshi; Baba, Sueki

1995-01-01

The simple structure of CdTe semiconductor detectors facilitates their downsizing, and their possible application to radiographic sensors has been studied. The escape of K X-rays from these detectors increases with reduction of their dimensions and affects the measurements of X- and gamma-ray spectra. K X-rays also produce crosstalk in multi-channel detectors with adjacent channels. Therefore, K X-rays which escape from the detector elements degrade both the precision of energy spectra and spatial resolution. The ratios of escape peak integrated counts to total photon counts for various sizes of CdTe single detectors were calculated for gamma rays using the Monte Carlo method. Also, escape and crosstalk ratios were simulated for the CdTe multi-channel detectors. The theoretical results were tested experimentally for 59.54-keV gamma rays from a 241 Am radioactive source. Results showed that escape ratios for single detectors were strongly dependent on element size and thickness. The escape and crosstalk ratios increased with closer channel pitch. The calculated results showed a good agreement with the experimental data. The calculations made it clear that K X-rays which escaped to neighboring channels induced crosstalk more frequently at smaller channel pitch in multichannel detectors. A radiation shielding grid which blocked incident photons between the boundary channels was also tested by experiment and by calculation. It was effective in reducing the probability of escape and crosstalk

The unfolding effects of transfer functions and processing of the pulse height distributions

Directory of Open Access Journals (Sweden)

Avdić Senada

2010-01-01

Full Text Available This paper deals with the improvements of the linear artificial neural network unfolding approach aimed at accurately determining the incident neutron spectrum. The effects of the transfer functions and pre-processing of the simulated pulse height distributions from liquid scintillation detectors on the artificial neural networks performance have been studied. A better energy resolution and higher reliability of the linear artificial neural network technique have been achieved after implementation of the results of this study. The optimized structure of the network was used to unfold both monoenergetic and continuous neutron energy spectra, such as the spectra of 252Cf and 241Am-Be sources, traditionally used in the nuclear safeguards experiments. We have demonstrated that the artificial neural network energy resolution of 0.1 MeV is comparable with the one obtained by the reference maximum likelihood expectation-maximization method which was implemented by using the one step late algorithm. Although the maximum likelihood algorithm provides the unfolded results of higher accuracy, especially for continuous neutron sources, the artificial neural network approach with the improved performances is more suitable for fast and robust determination of the neutron spectra with sufficient accuracy.

Multi-pulse chaotic motions of a rotor-active magnetic bearing system with time-varying stiffness

International Nuclear Information System (INIS)

Zhang, W.; Yao, M.H.; Zhan, X.P.

2006-01-01

In this paper, we investigate the Shilnikov type multi-pulse chaotic dynamics for a rotor-active magnetic bearings (AMB) system with 8-pole legs and the time-varying stiffness. The stiffness in the AMB is considered as the time-varying in a periodic form. The dimensionless equation of motion for the rotor-AMB system with the time-varying stiffness in the horizontal and vertical directions is a two-degree-of-freedom nonlinear system with quadratic and cubic nonlinearities and parametric excitation. The asymptotic perturbation method is used to obtain the averaged equations in the case of primary parametric resonance and 1/2 subharmonic resonance. It is found from the numerical results that there are the phenomena of the Shilnikov type multi-pulse chaotic motions for the rotor-AMB system. A new jumping phenomenon is discovered in the rotor-AMB system with the time-varying stiffness

TRANTHAC-1: transient thermal-hydraulic analysis code for HTGR core of multi-channel model

International Nuclear Information System (INIS)

Sato, Sadao; Miyamoto, Yoshiaki

1980-08-01

The computer program TRANTHAC-1 is for predicting thermal-hydraulic transient behavior in HTGR's core of pin-in-block type fuel elements, taking into consideration of the core flow distribution. The program treats a multi-channel model, each single channel representing the respective column composed of fuel elements. The fuel columns are grouped in flow control regions; each region is provided with an orifice assembly. In the region, all channels are of the same shape except one channel. Core heat is removed by downward flow of the control through the channel. In any transients, for given time-dependent power, total core flow, inlet coolant temperature and coolant pressure, the thermal response of the core can be determined. In the respective channels, the heat conduction in radial and axial direction are represented. And the temperature distribution in each channel with the components is calculated. The model and usage of the program are described. The program is written in FORTRAN-IV for computer FACOM 230-75 and it is composed of about 4,000 cards. The required core memory is about 75 kilowords. (author)

Multi spectral scaling data acquisition system

International Nuclear Information System (INIS)

Behere, Anita; Patil, R.D.; Ghodgaonkar, M.D.; Gopalakrishnan, K.R.

1997-01-01

In nuclear spectroscopy applications, it is often desired to acquire data at high rate with high resolution. With the availability of low cost computers, it is possible to make a powerful data acquisition system with minimum hardware and software development, by designing a PC plug-in acquisition board. But in using the PC processor for data acquisition, the PC can not be used as a multitasking node. Keeping this in view, PC plug-in acquisition boards with on-board processor find tremendous applications. Transputer based data acquisition board has been designed which can be configured as a high count rate pulse height MCA or as a Multi Spectral Scaler. Multi Spectral Scaling (MSS) is a new technique, in which multiple spectra are acquired in small time frames and are then analyzed. This paper describes the details of this multi spectral scaling data acquisition system. 2 figs

A 240-channel thick film multi-chip module for readout of silicon drift detectors

International Nuclear Information System (INIS)

Lynn, D.; Bellwied, R.; Beuttenmueller, R.; Caines, H.; Chen, W.; DiMassimo, D.; Dyke, H.; Elliott, D.; Grau, M.; Hoffmann, G.W.; Humanic, T.; Jensen, P.; Kleinfelder, S.A.; Kotov, I.; Kraner, H.W.; Kuczewski, P.; Leonhardt, B.; Li, Z.; Liaw, C.J.; LoCurto, G.; Middelkamp, P.; Minor, R.; Mazeh, N.; Nehmeh, S.; O'Conner, P.; Ott, G.; Pandey, S.U.; Pruneau, C.; Pinelli, D.; Radeka, V.; Rescia, S.; Rykov, V.; Schambach, J.; Sedlmeir, J.; Sheen, J.; Soja, B.; Stephani, D.; Sugarbaker, E.; Takahashi, J.; Wilson, K.

2000-01-01

We have developed a thick film multi-chip module for readout of silicon drift (or low capacitance ∼200 fF) detectors. Main elements of the module include a custom 16-channel NPN-BJT preamplifier-shaper (PASA) and a custom 16-channel CMOS Switched Capacitor Array (SCA). The primary design criteria of the module were the minimizations of the power (12 mW/channel), noise (ENC=490 e - rms), size (20.5 mmx63 mm), and radiation length (1.4%). We will discuss various aspects of the PASA design, with emphasis on the preamplifier feedback network. The SCA is a modification of an integrated circuit that has been previously described [1]; its design features specific to its application in the SVT (Silicon Vertex Tracker in the STAR experiment at RHIC) will be discussed. The 240-channel multi-chip module is a circuit with five metal layers fabricated in thick film technology on a beryllia substrate and contains 35 custom and commercial integrated circuits. It has been recently integrated with silicon drift detectors in both a prototype system assembly for the SVT and a silicon drift array for the E896 experiment at the Alternating Gradient Synchrotron at the Brookhaven National Laboratory. We will discuss features of the module's design and fabrication, report the test results, and emphasize its performance both on the bench and under experimental conditions

Salt intrusion in multi-channel estuaries: a case study in the Mekong Delta, Vietnam

Directory of Open Access Journals (Sweden)

A. D. Nguyen

2006-01-01

Full Text Available There is a well-tested theory for the computation of salt intrusion in alluvial estuaries that is fully analytical and predictive. The theory uses analytical equations to predict the mixing behaviour of the estuary based on measurable quantities, such as channel topography, river discharge and tidal characteristics. It applies to single-channel topographies and estuaries that demonstrate moderate tidal damping. The Mekong delta is a multi-channel estuary where the tide is damped due to a relatively strong river discharge (in the order of 2000 m3/s, even during the dry season. As a result the Mekong is a strongly riverine estuary. This paper aims to test if the theory can be applied to such a riverine multi-channel estuary, and to see if possible adjustments or generalisations need to be made. The paper presents salt intrusion measurements that were done by moving boat in 2005, to which the salt intrusion model was calibrated. The theory has been expanded to cater for tidal damping. Subsequently the model has been validated with observations made at fixed locations over the years 1998 and 1999. Finally it has been tested whether the Mekong calibration fits the overall predictive equations derived in other estuaries. The test has been successful and led to a slight adjustment of the predictive equation to cater for estuaries that experience a sloping bottom.

Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets

Science.gov (United States)

Zou, D. B.; Pukhov, A.; Yi, L. Q.; Zhou, H. B.; Yu, T. P.; Yin, Y.; Shao, F. Q.

2017-02-01

Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations.

First result from x-ray pulse height analyzer with radial scanning system for LHD

Science.gov (United States)

Muto, Sadatsugu; Morita, Shigeru

2001-01-01

Radial profiles of x-ray spectrum have been successfully obtained using an assembly of x-ray pulse height analyzer in large helical device. The observed profile is obtained from plasma heated by ICRF and neutral beam injection (NBI). As a detector, Si(Li) semiconductor is used with a histogramming memory and analog-to-digital converter (ADC) basically working at high counting rate up to 500 kcps. In routine operation a count rate of 62 kcps has been normally obtained with energy resolution better than 400 eV at iron Kα line. The assembly is equipped with four detectors and a radial scanning system which modulates sight lines of the detectors in major radius direction. The profiles of electron temperature and the intensity of metallic impurities have been obtained with a spatial resolution of a few centimeters. Measured electron temperature is in good agreement with that from Thomson scattering. The system is applicable to steady-state discharge. The design philosophy of the assembly and recent results on the performance tests are also presented.

Multi-channel unidirectional transmission of phononic crystal heterojunctions

Science.gov (United States)

Xu, Zhenlong; Tong, Jie; Wu, Fugen

2018-02-01

Two square steel columns are arranged in air to form two-dimensional square lattice phononic crystals (PNCs). Two PNCs can be combined into a non-orthogonal 45∘ heterojunction when the difference in the directional band gaps of the two PNC types is utilized. The finite element method is used to calculate the acoustic band structure, the heterogeneous junction transmission characteristics, acoustic field distribution, and many others. Results show that a non-orthogonal PNC heterojunction can produce a multi-channel unidirectional transmission of acoustic waves. With the square scatterer rotated, the heterojunction can select a frequency band for unidirectional transmission performance. This capability is particularly useful for constructing acoustic diodes with wide-bands and high-efficiency unidirectional transmission characteristics.

Multi-Channel RF System for MRI-Guided Transurethral Ultrasound Thermal Therapy

Science.gov (United States)

Yak, Nicolas; Asselin, Matthew; Chopra, Rajiv; Bronskill, Michael

2009-04-01

MRI-guided transurethral ultrasound thermal therapy is an approach to treating localized prostate cancer which targets precise deposition of thermal energy within a confined region of the gland. This treatment requires a system incorporating a heating applicator with multiple planar ultrasound transducers and associated RF electronics to control individual elements independently in order to achieve accurate 3D treatment. We report the design, construction, and characterization of a prototype multi-channel system capable of controlling 16 independent RF signals for a 16-element heating applicator. The main components are a control computer, microcontroller, and a 16-channel signal generator with 16 amplifiers, each incorporating a low-pass filter and transmitted/reflected power detection circuit. Each channel can deliver from 0.5 to 10 W of electrical power and good linearity from 3 to 12 MHz. Harmonic RF signals near the Larmor frequency of a 1.5 T MRI were measured to be below -30 dBm and heating experiments within the 1.5 T MR system showed no significant decrease in SNR of the temperature images. The frequency and power for all 16 channels could be changed in less than 250 ms, which was sufficiently rapid for proper performance of the control algorithms. A common backplane design was chosen which enabled an inexpensive, modular approach for each channel resulting in an overall system with minimal footprint.

Wall-cooling-induced mixed-convection flow recirculation in a vertical square-array multi-rod channel

International Nuclear Information System (INIS)

Luangdilok, W.; Todreas, N.E.

1989-01-01

This work investigated the structure of penetrative flow recirculation and associated flow conditions in a multi-rod channel induced by interassembly heat transfer that causes cooling through channel walls. Three investigation approaches, experimental, numerical, and analytical were employed in a complimentary fashion. Physical experiments involved water flow visualization and temperature measurement in a 4x4 rod square channel. Numerical experiments involved 3-dimensional simulations of water and sodium flow in a 2x2-rod channels. An approximate reverse flow model including Prandtl number effect was developed. A correlating equation based on the model and experiments was verified for water to correctly predict the trend of the 4x4-rod experimental penetration depth data. (orig.)

Measurements of void fraction by an improved multi-channel conductance void meter

International Nuclear Information System (INIS)

Song, Chul-Hwa; Chung, Moon Ki; No, Hee Cheon

1998-01-01

An improved multi-channel Conductance Void Meter (CVM) was developed to measure a void fraction. Its measuring principle is basically based upon the differences of electrical conductance of a two-phase mixture due to the variation of void fraction around a sensor. The sensor is designed to be flush-mounted to the inner wall of the test section to avoid the flow disturbances. The signal processor with three channels is specially designed so as to minimize the inherent error due to the phase difference between channels. It is emphasized that the guard electrodes are electrically shielded in order not to affect the measurements of two-phase mixture conductance, but to make the electric fields evenly distributed in a measuring volume. Void fraction is measured for bubbly and slug flow regimes in a vertical air-water loop, and statistical signal processing techniques are applied to show that CVM has a good dynamic resolution which is required to investigate the structural developments of bubbly flow and the propagation of void waves in a flow channel. (author)

An Economical Fast Discriminator for Nuclear Pulse Counting

International Nuclear Information System (INIS)

Issarachai, Opas; Punnachaiya, Suvit

2009-07-01

Full text: This research work was aimed to develop a fast discriminator at low cost but high capability for discrimination a nanosecond nuclear pulse. The fast discriminator can be used in association with fast photon counting system. The designed structure consisted of the ultra-fast voltage comparator using ADCMP601 integrated circuit, the monostable multivibrator with controllable pulse width output by propagation delay of logic gate, and the fast response buffer amplifier. The tested results of pulse height discrimination of 0-5 V nuclear pulse with 20 ns (FWHM) pulse width showed the correlation coefficient (R 2 ) between discrimination level and pulse height was 0.998, while the pulse rate more than 10 MHz could be counted. The 30 ns logic pulse width output revealed high stable and could be smoothly driven to low impedance load at 50 Ω. For pulse signal transmission to the counter, it was also found that the termination of reflected signal must be considered because it may cause pulse counting error

Hydraulic jumps in a channel

DEFF Research Database (Denmark)

Bonn, D.; Andersen, Anders Peter; Bohr, Tomas

2009-01-01

We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected......'s mixing-length theory with a mixing length that is proportional to the height of the fluid layer. Using averaged boundary-layer equations, taking into account the friction with the channel walls and the eddy viscosity, the flow both upstream and downstream of the jump can be understood. For the downstream...... subcritical flow, we assume that the critical height is attained close to the channel outlet. We use mass and momentum conservation to determine the position of the jump and obtain an estimate which is in rough agreement with our experiment. We show that the averaging method with a varying velocity profile...

Status of the upgraded version of the NRL GAMBLE II pulse power generator

International Nuclear Information System (INIS)

Boller, J.R.; Burton, J.K.; Shipman, J.D. Jr.

1979-01-01

The GAMBLE II water dielectric pulse power generator, in 1970, was the forerunner of the high energy (> 50 kJ) class of water dielectric generators. It has been redesigned internally to make maximum use of its original outer conductor shell and to optimize it for the positive polarity mode of operation for positive ion beam experimentation. The new design also initiates the use of an oil dielectric multi-channel switch at the output of the pulse forming line. This switch, because of its low capacitance, eliminates the need for an extra prepulse switch. The upgraded version has been tested up to power and energy levels which are nearly twice the original

Multi-Channel Multi-Radio Using 802.11 Based Media Access for Sink Nodes in Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Kok-Keong Loo

2011-05-01

Full Text Available The next generation surveillance and multimedia systems will become increasingly deployed as wireless sensor networks in order to monitor parks, public places and for business usage. The convergence of data and telecommunication over IP-based networks has paved the way for wireless networks. Functions are becoming more intertwined by the compelling force of innovation and technology. For example, many closed-circuit TV premises surveillance systems now rely on transmitting their images and data over IP networks instead of standalone video circuits. These systems will increase their reliability in the future on wireless networks and on IEEE 802.11 networks. However, due to limited non-overlapping channels, delay, and congestion there will be problems at sink nodes. In this paper we provide necessary conditions to verify the feasibility of round robin technique in these networks at the sink nodes by using a technique to regulate multi-radio multichannel assignment. We demonstrate through simulations that dynamic channel assignment scheme using multi-radio, and multichannel configuration at a single sink node can perform close to optimal on the average while multiple sink node assignment also performs well. The methods proposed in this paper can be a valuable tool for network designers in planning network deployment and for optimizing different performance objectives.

Multi-channel multi-radio using 802.11 based media access for sink nodes in wireless sensor networks.

Science.gov (United States)

Campbell, Carlene E-A; Khan, Shafiullah; Singh, Dhananjay; Loo, Kok-Keong

2011-01-01

The next generation surveillance and multimedia systems will become increasingly deployed as wireless sensor networks in order to monitor parks, public places and for business usage. The convergence of data and telecommunication over IP-based networks has paved the way for wireless networks. Functions are becoming more intertwined by the compelling force of innovation and technology. For example, many closed-circuit TV premises surveillance systems now rely on transmitting their images and data over IP networks instead of standalone video circuits. These systems will increase their reliability in the future on wireless networks and on IEEE 802.11 networks. However, due to limited non-overlapping channels, delay, and congestion there will be problems at sink nodes. In this paper we provide necessary conditions to verify the feasibility of round robin technique in these networks at the sink nodes by using a technique to regulate multi-radio multichannel assignment. We demonstrate through simulations that dynamic channel assignment scheme using multi-radio, and multichannel configuration at a single sink node can perform close to optimal on the average while multiple sink node assignment also performs well. The methods proposed in this paper can be a valuable tool for network designers in planning network deployment and for optimizing different performance objectives.

Multi-channel WDM RZ-to-NRZ format conversion at 50 Gbit/s based on single silicon microring resonator

DEFF Research Database (Denmark)

Ding, Yunhong; Peucheret, Christophe; Pu, Minhao

2010-01-01

We comprehensively analyze multiple WDM channels RZ-to- NRZ format conversion using a single microring resonator. The scheme relies on simultaneous suppression of the first order harmonic components in the spectra of all the RZ channels. An optimized silicon microring resonator with free spectral...... range of 100 GHz and Q value of 7900 is designed and fabricated for this purpose. Multi-channel RZ-to-NRZ format conversion is demonstrated experimentally at 50 Gbit/s for WDM channels with 200 GHz channel spacing using the fabricated device. Bit error rate (BER)measurements show very good conversion...

Operational Criteria for the Design of Front-Office Processes in Multi-Channel Service Delivery Systems

OpenAIRE

Sousa, Rui; Amorim, Marlene

2010-01-01

This paper identifies relevant operational factors that affect the design of front-office processes in Multi-Channel Service Delivery Systems. Based on two in-depth case studies in banking and telecommunications, we distinguish four operational factors: i) characteristics of the inputs and outputs of the service activities; ii) characteristics of the transformation taking place; iii) the expected utilization; iv) the economics of developing the activities in the channels. Building on these re...

Fuzzy coarse coding UP-grades A/D converters for pulse-height analysis

Energy Technology Data Exchange (ETDEWEB)

Casoli, P; Maranesi, P [Politecnico di Milano (Italy). Ist. di Ingegneria Nucleare

1983-01-15

Since they were first employed in nuclear pulse-height analysis, analog-to-digital converters show an evolution characterized by a continuous increase in their amplitude resolution. This trend looks as if it will continue in the immediate future but this forecast disagrees with the fact that the circuit complexity of the ADCs realized by conventional techniques rises sharply beyond 12 bit resolution. This paper describes and proposes a new A/D encoding technique. A successive-approximation ADC operating over a limited input range and having correspondingly a reduced resolution is employed. In order to adapt the input signal to this dynamic limitation, the signal is at first roughtly and quickly estimated by a flash converter and then, if necessary, an analog level is subtracted through a DAC. The input digit of this DAC is added to the result of the successive-approximations conversion to get the final correct result. The inherent differential non-linearities of the successive-approximations ADC and of the DAC are avoided by the combined actions of a sliding scale circuit and of an innovative circuit named 'shaker'. The satisfactory performance of the encoder has been experimentally verified through a 13 bit prototype. The simplicity of the proposed technique in comparison to conventional ones leads to the possibility of further raising the standard performance of nuclear spectroscopy ADCs.

Distributed capillary adiabatic tissue homogeneity model in parametric multi-channel blind AIF estimation using DCE-MRI.

Science.gov (United States)

Kratochvíla, Jiří; Jiřík, Radovan; Bartoš, Michal; Standara, Michal; Starčuk, Zenon; Taxt, Torfinn

2016-03-01

One of the main challenges in quantitative dynamic contrast-enhanced (DCE) MRI is estimation of the arterial input function (AIF). Usually, the signal from a single artery (ignoring contrast dispersion, partial volume effects and flow artifacts) or a population average of such signals (also ignoring variability between patients) is used. Multi-channel blind deconvolution is an alternative approach avoiding most of these problems. The AIF is estimated directly from the measured tracer concentration curves in several tissues. This contribution extends the published methods of multi-channel blind deconvolution by applying a more realistic model of the impulse residue function, the distributed capillary adiabatic tissue homogeneity model (DCATH). In addition, an alternative AIF model is used and several AIF-scaling methods are tested. The proposed method is evaluated on synthetic data with respect to the number of tissue regions and to the signal-to-noise ratio. Evaluation on clinical data (renal cell carcinoma patients before and after the beginning of the treatment) gave consistent results. An initial evaluation on clinical data indicates more reliable and less noise sensitive perfusion parameter estimates. Blind multi-channel deconvolution using the DCATH model might be a method of choice for AIF estimation in a clinical setup. © 2015 Wiley Periodicals, Inc.

Multi-Dielectric Brownian Dynamics and Design-Space-Exploration Studies of Permeation in Ion Channels.

Science.gov (United States)

Siksik, May; Krishnamurthy, Vikram

2017-09-01

This paper proposes a multi-dielectric Brownian dynamics simulation framework for design-space-exploration (DSE) studies of ion-channel permeation. The goal of such DSE studies is to estimate the channel modeling-parameters that minimize the mean-squared error between the simulated and expected "permeation characteristics." To address this computational challenge, we use a methodology based on statistical inference that utilizes the knowledge of channel structure to prune the design space. We demonstrate the proposed framework and DSE methodology using a case study based on the KcsA ion channel, in which the design space is successfully reduced from a 6-D space to a 2-D space. Our results show that the channel dielectric map computed using the framework matches with that computed directly using molecular dynamics with an error of 7%. Finally, the scalability and resolution of the model used are explored, and it is shown that the memory requirements needed for DSE remain constant as the number of parameters (degree of heterogeneity) increases.

Pulse number control of electrical resistance for multi-level storage based on phase change

International Nuclear Information System (INIS)

Nakayama, K; Takata, M; Kasai, T; Kitagawa, A; Akita, J

2007-01-01

Phase change nonvolatile memory devices composed of SeSbTe chalcogenide semiconductor thin film were fabricated. The resistivity of the SeSbTe system was investigated to apply to multi-level data storage. The chalcogenide semiconductor acts as a programmable resistor that has a large dynamic range. The resistance of the chalcogenide semiconductor can be set to intermediate resistances between the amorphous and crystalline states using electric pulses of a specified power, and it can be controlled by repetition of the electric pulses. The size of the memory cell used in this work is 200 nm thick with a contact area of 1 μm diameter. The resistance of the chalcogenide semiconductor gradually varies from 41 kΩ to 840 Ω within octal steps. The resistance of the chalcogenide semiconductor decreases with increasing number of applied pulses. The step-down characteristic of the resistance can be explained as the crystalline region of the active phase change region increases with increasing number of applied pulses. The extent of crystallization was also estimated by the overall resistivity of the active region of the memory cell

CAMAC differential pulse discriminator-counter

International Nuclear Information System (INIS)

Tselikov, N.V.

1987-01-01

Differential pulse discriminator-counter for Moessbauer spectrometer is described. Input pulse setting into the channel is performed according to the following algorithm: the pulse is transmitted to the channel depending on the fact whether the preceding pulse has got to the discrimination window or not. The circuit does not contain delay lines, taking into account the delay of a signal from the upper level discriminator in relation to the lower level discriminator signal, which is connected with input pulse rise finite time, which in turn allows one to reduce the discriminator dead time up to the operation time of threshold circuits. The pulse counting rate is 150 MHz, input signal amplitude is ±3 V, dead time is 6 ns, delay time from input to output is 14 ns. The unit is made in CAMAC system

A customizable multi-channel loudness compensation method based on WDRC for digital hearing aids

Science.gov (United States)

Hu, Jiebin; Wang, Mingjiang; Ma, Min

2017-08-01

Loudness compensation is the most significant signal processing algorithm in digital hearing aids at present. An algorithm of multi-channel loudness compensation for embedded system has been put forward in this paper. The number of channels is customizable in this algorithm. The algorithm can set different number and different width of channels for each patient based on frequency domain wide dynamic range compression. First, according to the requirement of patient to divide the frequency domain into multiple unequal frequency bands. And then calculate the gain of each channel according to the input-output curve of sound pressure level. Finally, the time-domain impulse response of gain is computed from Mel filter banks. It is used in conjunction with speech enhancement processing in hearing aids. Simulation results show that the algorithm can effectively enhance the loudness for different frequencies.

Monitoring small pioneer trees in the forest-tundra ecotone: using multi-temporal airborne laser scanning data to model height growth.

Science.gov (United States)

Hauglin, Marius; Bollandsås, Ole Martin; Gobakken, Terje; Næsset, Erik

2017-12-08

Monitoring of forest resources through national forest inventory programmes is carried out in many countries. The expected climate changes will affect trees and forests and might cause an expansion of trees into presently treeless areas, such as above the current alpine tree line. It is therefore a need to develop methods that enable the inclusion of also these areas into monitoring programmes. Airborne laser scanning (ALS) is an established tool in operational forest inventories, and could be a viable option for monitoring tasks. In the present study, we used multi-temporal ALS data with point density of 8-15 points per m 2 , together with field measurements from single trees in the forest-tundra ecotone along a 1500-km-long transect in Norway. The material comprised 262 small trees with an average height of 1.78 m. The field-measured height growth was derived from height measurements at two points in time. The elapsed time between the two measurements was 4 years. Regression models were then used to model the relationship between ALS-derived variables and tree heights as well as the height growth. Strong relationships between ALS-derived variables and tree heights were found, with R 2 values of 0.93 and 0.97 for the two points in time. The relationship between the ALS data and the field-derived height growth was weaker, with R 2 values of 0.36-0.42. A cross-validation gave corresponding results, with root mean square errors of 19 and 11% for the ALS height models and 60% for the model relating ALS data to single-tree height growth.

S100 lathe bed pulse generator applied to pulsed nuclear magnetic resonance

International Nuclear Information System (INIS)

Cernicchiaro, G.R.C.; Rudge, M.G.; Albuquerque, M.P.

1989-01-01

The project and construction of four channel pulse generator in the S100 standard plate and its control software for microcomputer are described. The microcomputer has total control on the pulse generator, which has seven programable parameters, defining the position of four pulses and the width for the three first ones. This pulse generator is controlled by a software developed in c language, and is used in pulsed nuclear magnetic resonance experiences. (M.C.K.) [pt

Drainage development and incision rates in an Upper Pleistocene Basalt-Limestone Boundary Channel: The Sa'ar Stream, Golan Heights, Israel

Science.gov (United States)

Shtober-Zisu, N.; Inbar, M.; Mor, D.; Jicha, B. R.; Singer, B. S.

2018-02-01

Long-term fluvial incision processes and corresponding geomorphic evolution are difficult to quantify, especially in complex systems affected by lithological and tectonic factors. Volcanic landscapes offer the most appropriate environment for the study of landscape evolution, as there is a clear starting time of formation and the lithology is homogenous. In the present study we aim to: (1) analyse the interplay of construction and incision processes throughout eruptive activity; (2) study fluvial erosion processes; (3) analyse sedimentary and volcanic lithological responses to channel erosion; and (4) calculate the incision rates in young basaltic bedrock. We have integrated existing and new 40Ar/39Ar ages of lava flows with estimates of channel geometry and tectonic activity, and considered process geomorphology concepts, to fully understand evolution of a bedrock channel incised at the boundary between basalts and sedimentary rocks with coeval active volcanic processes forcing drainage evolution. Our findings indicate that the Sa'ar basin evolution is controlled by: (1) rock strength of the mixed lithology; (2) alternating cycles of volcanic activity followed by erosion and incision; and (3) the Plio-Pleistocene uplift of Mt. Hermon. The carbonate slopes composing the southern flank of Mt. Hermon are moderate (18-26%) while the basalt slopes deriving from the Golan Heights are much steeper (26-51%). The highly erodible sedimentary rocks at Mt. Hermon's piedmont accelerated river incision, shaping a 650 m wide by 100 m deep canyon. Inside the canyon, the steep channel slope (8.6%) enables downstream movement of large boulders, including autochthonous mega-blocks (D90 size > 2.5 m); 24 knickpoints were identified using DS plots, developed within a knick zone over a distance of 6 km. The brittle and porous structure of the rubbly and blocky interflow layers (clinkers), interbedded between two massive basalt flows, enhances erosion and accelerates scouring of the

Optical fiber link for transmission of 1-nJ femtosecond laser pulses at 1550 nm

DEFF Research Database (Denmark)

Eichhorn, Finn; Olsson, Rasmus Kjelsmark; Buron, Jonas Christian Due

2010-01-01

We report on numerical and experimental characterization of the performance of a fiber link optimized for the delivery of sub-100-fs laser pulses at 1550 nm over several meters of fiber. We investigate the power handling capacity of the link, and demonstrate all-fiber delivery of 1-nJ pulses over...... a distance of 5.3 m. The fiber link consists of dispersion-compensating fiber (DCF) and standard single-mode fiber. The optical pulses at different positions in the fiber link are measured using frequency-resolved optical gating (FROG). The results are compared with numerical simulations of the pulse...... propagation based on the generalized nonlinear Schrödinger equation. The high input power capacity of the fiber link allows the splitting and distribution of femtosecond pulses to an array of fibers with applications in multi-channel fiber-coupled terahertz time-domain spectroscopy and imaging systems. We...

Computational Fluid Dynamics Study of Channel Geometric Effect for Fischer-Tropsch Microchannel Reactor

International Nuclear Information System (INIS)

Na, Jonggeol; Jung, Ikhwan; Kshetrimayum, Krishnadash S.; Park, Seongho; Park, Chansaem; Han, Chonghun

2014-01-01

Driven by both environmental and economic reasons, the development of small to medium scale GTL(gas-to-liquid) process for offshore applications and for utilizing other stranded or associated gas has recently been studied increasingly. Microchannel GTL reactors have been preferred over the conventional GTL reactors for such applications, due to its compactness, and additional advantages of small heat and mass transfer distance desired for high heat transfer performance and reactor conversion. In this work, multi-microchannel reactor was simulated by using commercial CFD code, ANSYS FLUENT, to study the geometric effect of the microchannels on the heat transfer phenomena. A heat generation curve was first calculated by modeling a Fischer-Tropsch reaction in a single-microchannel reactor model using Matlab-ASPEN integration platform. The calculated heat generation curve was implemented to the CFD model. Four design variables based on the microchannel geometry namely coolant channel width, coolant channel height, coolant channel to process channel distance, and coolant channel to coolant channel distance, were selected for calculating three dependent variables namely, heat flux, maximum temperature of coolant channel, and maximum temperature of process channel. The simulation results were visualized to understand the effects of the design variables on the dependent variables. Heat flux and maximum temperature of cooling channel and process channel were found to be increasing when coolant channel width and height were decreased. Coolant channel to process channel distance was found to have no effect on the heat transfer phenomena. Finally, total heat flux was found to be increasing and maximum coolant channel temperature to be decreasing when coolant channel to coolant channel distance was decreased. Using the qualitative trend revealed from the present study, an appropriate process channel and coolant channel geometry along with the distance between the adjacent

Advanced Modular, Multi-Channel, High Speed Fiber Optic Sensing System for Acoustic Emissions Monitoring, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to prove the feasibility of innovations based on ultra-light-weight, ultra-high-speed, multi-channel,...

Sparsity-based multi-height phase recovery in holographic microscopy

KAUST Repository

Rivenson, Yair

2016-11-30

High-resolution imaging of densely connected samples such as pathology slides using digital in-line holographic microscopy requires the acquisition of several holograms, e.g., at >6–8 different sample-to-sensor distances, to achieve robust phase recovery and coherent imaging of specimen. Reducing the number of these holographic measurements would normally result in reconstruction artifacts and loss of image quality, which would be detrimental especially for biomedical and diagnostics-related applications. Inspired by the fact that most natural images are sparse in some domain, here we introduce a sparsity-based phase reconstruction technique implemented in wavelet domain to achieve at least 2-fold reduction in the number of holographic measurements for coherent imaging of densely connected samples with minimal impact on the reconstructed image quality, quantified using a structural similarity index. We demonstrated the success of this approach by imaging Papanicolaou smears and breast cancer tissue slides over a large field-of-view of ~20 mm2 using 2 in-line holograms that are acquired at different sample-to-sensor distances and processed using sparsity-based multi-height phase recovery. This new phase recovery approach that makes use of sparsity can also be extended to other coherent imaging schemes, involving e.g., multiple illumination angles or wavelengths to increase the throughput and speed of coherent imaging.

Sparsity-based multi-height phase recovery in holographic microscopy

Science.gov (United States)

Rivenson, Yair; Wu, Yichen; Wang, Hongda; Zhang, Yibo; Feizi, Alborz; Ozcan, Aydogan

2016-11-01

High-resolution imaging of densely connected samples such as pathology slides using digital in-line holographic microscopy requires the acquisition of several holograms, e.g., at >6-8 different sample-to-sensor distances, to achieve robust phase recovery and coherent imaging of specimen. Reducing the number of these holographic measurements would normally result in reconstruction artifacts and loss of image quality, which would be detrimental especially for biomedical and diagnostics-related applications. Inspired by the fact that most natural images are sparse in some domain, here we introduce a sparsity-based phase reconstruction technique implemented in wavelet domain to achieve at least 2-fold reduction in the number of holographic measurements for coherent imaging of densely connected samples with minimal impact on the reconstructed image quality, quantified using a structural similarity index. We demonstrated the success of this approach by imaging Papanicolaou smears and breast cancer tissue slides over a large field-of-view of ~20 mm2 using 2 in-line holograms that are acquired at different sample-to-sensor distances and processed using sparsity-based multi-height phase recovery. This new phase recovery approach that makes use of sparsity can also be extended to other coherent imaging schemes, involving e.g., multiple illumination angles or wavelengths to increase the throughput and speed of coherent imaging.

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

Science.gov (United States)

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

1972-01-01

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

An integrated analog O/E/O link for multi-channel laser neurons

Energy Technology Data Exchange (ETDEWEB)

Nahmias, Mitchell A., E-mail: mnahmias@princeton.edu; Tait, Alexander N.; Tolias, Leonidas; Chang, Matthew P.; Ferreira de Lima, Thomas; Shastri, Bhavin J.; Prucnal, Paul R. [Electrical Engineering Department, Princeton University, 41 Olden St, Princeton, New Jersey 08540 (United States)

2016-04-11

We demonstrate an analog O/E/O electronic link to allow integrated laser neurons to accept many distinguishable, high bandwidth input signals simultaneously. This device utilizes wavelength division multiplexing to achieve multi-channel fan-in, a photodetector to sum signals together, and a laser cavity to perform a nonlinear operation. Its speed outpaces accelerated-time neuromorphic electronics, and it represents a viable direction towards scalable networking approaches.

Ion Channel Conformation and Oligomerization Assessment by Site-Directed Spin Labeling and Pulsed-EPR.

Science.gov (United States)

Pliotas, Christos

2017-01-01

Mechanosensitive (MS) ion channels are multimeric integral membrane proteins that respond to increased lipid bilayer tension by opening their nonselective pores to release solutes and relieve increased cytoplasmic pressure. These systems undergo major conformational changes during gating and the elucidation of their mechanism requires a deep understanding of the interplay between lipids and proteins. Lipids are responsible for transmitting lateral tension to MS channels and therefore play a key role in obtaining a molecular-detail model for mechanosensation. Site-directed spin labeling combined with electron paramagnetic resonance (EPR) spectroscopy is a powerful spectroscopic tool in the study of proteins. The main bottleneck for its use relates to challenges associated with successful isolation of the protein of interest, introduction of paramagnetic labels on desired sites, and access to specialized instrumentation and expertise. The design of sophisticated experiments, which combine a variety of existing EPR methodologies to address a diversity of specific questions, require knowledge of the limitations and strengths, characteristic of each particular EPR method. This chapter is using the MS ion channels as paradigms and focuses on the application of different EPR techniques to ion channels, in order to investigate oligomerization, conformation, and the effect of lipids on their regulation. The methodology we followed, from the initial strategic selection of mutants and sample preparation, including protein purification, spin labeling, reconstitution into lipid mimics to the complete set-up of the pulsed-EPR experiments, is described in detail. © 2017 Elsevier Inc. All rights reserved.

Dynamic analysis of multiple nuclear-coupled boiling channels based on a multi-point reactor model

International Nuclear Information System (INIS)

Lee, J.D.; Pan Chin

2005-01-01

This work investigates the non-linear dynamics and stabilities of a multiple nuclear-coupled boiling channel system based on a multi-point reactor model using the Galerkin nodal approximation method. The nodal approximation method for the multiple boiling channels developed by Lee and Pan [Lee, J.D., Pan, C., 1999. Dynamics of multiple parallel boiling channel systems with forced flows. Nucl. Eng. Des. 192, 31-44] is extended to address the two-phase flow dynamics in the present study. The multi-point reactor model, modified from Uehiro et al. [Uehiro, M., Rao, Y.F., Fukuda, K., 1996. Linear stability analysis on instabilities of in-phase and out-of-phase modes in boiling water reactors. J. Nucl. Sci. Technol. 33, 628-635], is employed to study a multiple-channel system with unequal steady-state neutron density distribution. Stability maps, non-linear dynamics and effects of major parameters on the multiple nuclear-coupled boiling channel system subject to a constant total flow rate are examined. This study finds that the void-reactivity feedback and neutron interactions among subcores are coupled and their competing effects may influence the system stability under different operating conditions. For those cases with strong neutron interaction conditions, by strengthening the void-reactivity feedback, the nuclear-coupled effect on the non-linear dynamics may induce two unstable oscillation modes, the supercritical Hopf bifurcation and the subcritical Hopf bifurcation. Moreover, for those cases with weak neutron interactions, by quadrupling the void-reactivity feedback coefficient, period-doubling and complex chaotic oscillations may appear in a three-channel system under some specific operating conditions. A unique type of complex chaotic attractor may evolve from the Rossler attractor because of the coupled channel-to-channel thermal-hydraulic and subcore-to-subcore neutron interactions. Such a complex chaotic attractor has the imbedding dimension of 5 and the

Application of pulsed multi-ion irradiations in radiation damage research: A stochastic cluster dynamics simulation study

Science.gov (United States)

Hoang, Tuan L.; Nazarov, Roman; Kang, Changwoo; Fan, Jiangyuan

2018-07-01

Under the multi-ion irradiation conditions present in accelerated material-testing facilities or fission/fusion nuclear reactors, the combined effects of atomic displacements with radiation products may induce complex synergies in the structural materials. However, limited access to multi-ion irradiation facilities and the lack of computational models capable of simulating the evolution of complex defects and their synergies make it difficult to understand the actual physical processes taking place in the materials under these extreme conditions. In this paper, we propose the application of pulsed single/dual-beam irradiation as replacements for the expensive steady triple-beam irradiation to study radiation damages in materials under multi-ion irradiation.

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

Science.gov (United States)

O'Bryan, J. B.; Romero-Talamás, C. A.; Woodruff, S.

2018-03-01

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization during multi-pulse coaxial helicity injection in the Sustained Spheromak Physics eXperiment. We describe multiple distinct phases of spheromak evolution, starting from vacuum magnetic fields and the formation of the initial magnetic flux bubble through multiple refluxing pulses and the eventual onset of the column mode instability. Experimental and computational magnetic diagnostics agree on the onset of the column mode instability, which first occurs during the second refluxing pulse of the simulated discharge. Our computations also reproduce the injector voltage traces, despite only specifying the injector current and not explicitly modeling the external capacitor bank circuit. The computations demonstrate that global magnetic evolution is fairly robust to different transport models and, therefore, that a single fluid-temperature model is sufficient for a broader, qualitative assessment of spheromak performance. Although discharges with similar traces of normalized injector current produce similar global spheromak evolution, details of the current distribution during the column mode instability impact the relative degree of poloidal flux amplification and magnetic helicity content.

Schlieren Visualization of the Energy Addition by Multi Laser Pulse in Hypersonic Flow

International Nuclear Information System (INIS)

Oliveira, A. C.; Minucci, M. A. S.; Toro, P. G. P.; Chanes, J. B. Jr; Myrabo, L. N.

2008-01-01

The experimental results of the energy addition by multi laser pulse in Mach 7 hypersonic flow are presented. Two high power pulsed CO 2 TEA lasers (TEA1 5.5 J, TEA2 3.9 J) were assembled sharing the same optical cavity to generate the plasma upstream of a hemispherical model installed in the tunnel test section. The lasers can be triggered with a selectable time delay and in the present report the results obtained with delay between 30 μs and 80 μs are shown. The schlieren technique associated with a high speed camera was used to accomplish the influence of the energy addition in the mitigation of the shock wave formed on the model surface by the hypersonic flow. A piezoelectric pressure transducer was used to obtain the time history of the impact pressure at stagnation point of the model and the pressure reduction could be measured. The total recovery of the shock wave between pulses as well as the prolonged effect of the mitigation without recovery was observed by changing the delay

Characteristics of crosstalk in the reproduced output of a newly developed multi-channel MR head

International Nuclear Information System (INIS)

Machida, K.; Hayashi, N.; Yoneda, Y.; Numazawa, J.; Kohro, M.; Tanabe, T.

2001-01-01

We prepared the multi-channel magnetoresistive head with a simple structural design and it has the advantages of high-density recording and ultra-high transfer rate. Characteristics of crosstalk in the reproduced output of our head have been estimated by a micromagnetic calculation using the Landau-Lifshitz-Gilbert (LLG) equation, while the specimen head was fabricated and evaluated. As a result, by applying a magnetic field of 40 Oe only between adjacent channels, the crosstalk was much decreased without reducing the reproduced output

Multi-scale viscosity model of turbulence for fully-developed channel flows

International Nuclear Information System (INIS)

Kriventsev, V.; Yamaguchi, A.; Ninokata, H.

2001-01-01

The full text follows. Multi-Scale Viscosity (MSV) model is proposed for estimation of the Reynolds stresses in turbulent fully-developed flow in a straight channel of an arbitrary shape. We assume that flow in an ''ideal'' channel is always stable, i.e. laminar, but turbulence is developing process of external perturbations cased by wall roughness and other factors. We also assume that real flows are always affected by perturbations of every scale lower than the size of the channel. And the turbulence is generated in form of internal, or ''turbulent'' viscosity increase to preserve stability of ''disturbed'' flow. The main idea of MSV can be expressed in the following phenomenological rule: A local deformation of axial velocity can generate the turbulence with the intensity that keeps the value of local turbulent Reynolds number below some critical value. Here, the local turbulent Reynolds number is defined as a product of value of axial velocity deformation for a given scale and generic length of this scale divided by accumulated value of laminar and turbulent viscosity of lower scales. In MSV, the only empirical parameter is the critical Reynolds number that is estimated to be around 100. It corresponds for the largest scale which is hydraulic diameter of the channel and, therefore represents the regular Reynolds number. Thus, the value Re=100 corresponds to conditions when turbulent flow can appear in case of ''significant'' (comparable with size of channel) velocity disturbance in boundary and/or initial conditions for velocity. Of course, most of real flows in channels with relatively smooth walls remain laminar for this small Reynolds number because of absence of such ''significant'' perturbations. MSV model has been applied to the fully-developed turbulent flows in straight channels such as a circular tube and annular channel. Friction factor and velocity profiles predicted with MSV are in a very good agreement with numerous experimental data. Position of

Dynamics of the spectral behaviour of an ultrashort laser pulse in an argon-gas-filled capillary discharge-preformed plasma channel

Directory of Open Access Journals (Sweden)

Sakai S.

2013-11-01

Full Text Available We have reported the argon plasma waveguide produced in an alumina (Al2O3 capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 1016  W/cm2. A one-dimensional magnetohydrodynamic (MHD code was used to evaluate the average degree of ionization of Ar in the preformed plasma channel. The spectrum of the propagated laser pulse in the Ar plasma waveguide was not modified and was well reproduced by a particle-in-cell (PIC simulation under initial ion charge state of Ar3+ in the preformed plasma waveguide. The optimum timing for the laser pulse injection was around 150 ns after initiation of a discharge with a peak current of 200 A.

A suspended boron foil multi-wire proportional counter neutron detector

Energy Technology Data Exchange (ETDEWEB)