Single-channel Mode Research Articles

A 10-Bit Multichannel Digitizer ASIC for Detectors in Particle Physics Experiments

The design and measurement results of a multi-channel power scalable 10-bit digitizer ASIC developed for the luminosity detector at the future linear colliders (ILC/CLIC) are discussed. The 8 channel prototype with different modes of output data serialization was designed and fabricated in a 0.35 μm CMOS technology. The ASIC works for sampling rates from about 10 kS/s to 25 MS/s (50 MS/s in single channel mode) allowing linear scaling of ADCs and serializer power consumption (0.8 mW/MS/s ADC core, 1.2 mW/MS/s total per channel). A wide spectrum of static and dynamic measurements confirm very good ADC resolution (ENOB = 9.7 bits), excellent channel uniformity and negligible crosstalk. To profit from non-continuous detector operation in linear collider experiments and to save power consumption, fast periodic power pulsing is implemented.

EXPERIMENTAL COMPARISON OF REMEDIAL SINGLE-CHANNEL OPERATIONS FOR REDUNDANT FLUX-SWITCHING PERMANENT-MAGNET MOTOR DRIVE

Redundant ∞ux-switching permanent-magnet (R-FSPM) motor is a new fault-tolerant machine having PMs in the stator, ofiering high e-ciency, high reliability, and robust structure. This paper proposes two remedial control strategies for fault-tolerant operations of the R-FSPM motor drive in the single-channel (SC) mode. First, by doubling the healthy-channel currents, the reduced torque due to one channel loss can be remedied, the so-called remedial brushless AC (BLAC) operation mode. Second, by injecting harmonic current (IHC) considering harmonic back-EMF efiect, the reduced torque can also be smoothly remedied, the so-c alled remedial IHC operation mode. Finally, both of the proposed remedial control strategies are verifled by co-simulation and experimentation, hence conflrming the validity of the proposed fault-tolerant R-FSPM motor drive.

The analyses of the heat-up process of a planar, anode-supported solid oxide fuel cell using the dual-channel heating strategy

In the present study, a finite-volume (FV) model has been developed to investigate the thermal behavior, the heat-up time and the corresponding temperature gradient for an anode-supported planar SOFC during the heat-up process. A methane burner is employed for the heat-up of the SOFC. Effects of the burner power and the flow configuration on the temperature distribution, the effective maximum-temperature-gradient, the heat-up time and the required energy in the heat-up process are investigated. The numerical results obtained from the present study show that the single-channel mode is impractical for the SOFC heat-up due to the lengthy heat-up time. For a fixed-power burner, the required heat-up time for the counter-flow configuration is about 25% less than that of the co-flow configuration. For the counter-flow configuration, the temperature gradient is averagely about 17% larger than that for the co-flow configuration. The total energy required for the counter-flow configuration is about 20% less than that for the co-flow configuration. The counter-flow configuration is superior to the others as far as the heat-up time and the required energy are concerned, although it yields a relatively higher maximum-temperature-gradient.

Comparison of transient and steady-state performances analysis for a dual-channel switched reluctance machine operation under different modes

This study deals with the comparison of the dynamic modelling, the transient and steady-state performances analysis and experimental verification for a 12/8 dual-channel switched reluctance machine (DCSRM) under single- and dual-channel operation modes. The DCSRM has inherent short flux paths capability, and the magnetic circuits for both the channels share most of the magnetic real estate in the machine under dual-channel excitation mode. According to the different flux patterns, the dynamic models for the DCSRM operating under different modes are presented. In this proposed dual-channel operation model, the mutual coupling between different phases in each channel of the DCSRM is considered. By using the dynamic models, various transient and steady-state performances such as starting up speed under closed-loop control, phase currents, phase flux linkages, total torque characteristics and sudden change in torque operation are predicted and compared for the DCSRM under different modes and excitation conditions. It is shown that when the DCSRM operation is under dual-channel mode, it has faster acceleration performance and the torque is more than two times of that under single-channel mode. Finally, an experimental laboratory set-up based on digital signal processor and complex programmable logic device (CPLD) is built, which verify the proposed modelling and analysis. The experimental results of transient and steady-state performances are compared with the simulation results in the DCSRM systems under single- and dual-channel operation modes.

Dynamic Modeling and Performance Prediction for Dual-Channel Switched Reluctance Machine Considering Mutual Coupling

Switched reluctance machines (SRMs) are normally designed and applied as 6/4 or 8/6 single-channel SRMs. However, recent efforts with 12/8 dual-channel SRMs (DCSRMs) have spurred interest. The 12/8 DCSRM is driven by two independent sets of power electronic circuits with dual control channels, and the two channels would have strong interactions between each other due to the magnetic mutual coupling for each channel. We propose a dynamic modeling strategy that accounts for the effect of mutual coupling of a DCSRM. First, we illustrate the flux patterns of a DCSRM under different operation modes. Then, we use an indirect experimental procedure to measure the static self and mutual flux linkages for the DCSRM. By using the measured flux linkage data, we describe a simulation model for a DCSRM operating in single-channel mode and dual-channel mode in which the mutual coupling is considered. We predict and compare the dynamic performance characteristics such as phase currents, flux linkages, energy conversion, and static torque under different operation modes and excitation conditions. Finally, we compare the simulation and experimental results for four operating conditions in DCSRM systems in single-channel mode and dual-channel mode. The proposed modeling strategy for the DCSRM is quite accurate.

Simultaneous Recording Of Ligand-binding And Channel-gating On Individual Nicotinic-acetylcholine Receptors In Living Cells

Simultaneously measuring both the ligand-binding and the gating of ligand-gated ion channels will provide important novel insight in receptor and channel function (see e.g. Edelstein et. al.). Such measurements require a fluorescently labeled agonist as ligand, single molecule sensitive optical and electrical detection, micro-second time-resolution, and optimal alignment of the optical and electrophysiological single-channel acquisition parts.Here we present first results from simultaneously measurements of ligand-binding and channel gating of individual prototypical ligand-gated ion channels in living cells, using APD-based fast confocal detection and conventional patch-clamping in single channel mode. In order to reach a reasonable throughput of experiments, it was essential that the sample, patch-pipette and the confocal volume could be moved independently and be aligned with micrometer precision.We show data from nicotinic-acetylcholine receptors, expressed in HEK293 cells and fluorescently labeled epibatidine as agonist, to elucidate details of the channel gating.S.J. Edelstein, O. Schaad & J.P. Changeux: Biochmistry;1997; 36(45), 13755

Autofluorescence spectroscopy and imaging of Platymonas subcordiformis irradiated by diode laser based on LSCM

Autofluorescence spectra and optical imaging of Platymonas subcordiformis after irradiation of diode laser were observed via laser scanning confocal microscopy (LSCM). With 488 nm Ar(+) laser excitation, the horizontal and vertical dimensions of a cup-shaped chloroplast of the irradiation group increased about 10% compared with the control group. The fluorescence spectra were similar between irradiation group and control group with a maximum fluorescence band around 682 nm, whereas the former has a higher intensity. Image of a small circular substance with stronger two-photon autofluorescence (TPA) was obtained when using two-photon excitation wavelength of 800 nm in single-channel mode. Further analysis by the 800 nm excitation based on two independent-channels mode showed an emission band of the small circular substance around 376-505 nm, which corresponded to the eyespot of P. subcordiformis. In lambda scanning mode, with two-photon wavelength of 800 nm excitation, six fluorescence peaks that are located at 465, 520, 560, 617, 660 and 680 nm were observed; the fluorescence intensity of the irradiation group was higher than that of the control group, especially at 520, 560 and 617 nm. As a conclusion, diode laser irradiation can promote chloroplast growth of P. subcordiformis cells in the form of expanding area and the increasing content of protein, phospholipids and chlorophyll. LSCM, especially TPA imaging based on femtosecond laser excitation, provides a nondestructive, real-time and accurate method to study changes of living algal cells under laser irradiation and other environmental factors.

Focus on test and measurement

Focus on test and measurement

Anionic and cationic photofragmentation of core-excited N2O

We have measured all detectable cationic and anionic fragments in single-channel mode fromN2Oas a function of photon energy in the vicinity of the nitrogen 1s core-levelthreshold. Due to the high degree of localization of the core electrons, the twoexcitations Nt1s → 3π*and Nc1s → 3π*show high levels of site-selective behaviour. The observedpartial ion yield for the sole anionic fragment, O−,in conjunction with the partial cation yields, confirms our previous demonstrationof anion-yield spectroscopy as a unique tool to identify core-level shaperesonances.

High-Speed Data Acquisition System and Receiver Configurations for Time-Domain Radiofrequency Electron Paramagnetic Resonance Spectroscopy and Imaging

Design strategies, system configuration, and operation of a dual-channel data acquisition system for a radiofrequency (RF) time-domain electron paramagnetic resonance (EPR) spectrometer/imager operating at 300 MHz are described. This system wasconfigured to incorporate high-speed analog-to-digital conversion (ADC) and summation capabilities with both internal and external triggering via GPIB interface. The sampling rate of the ADC is programmable up to a maximum of 1 GS/s when operating in a dual-channel mode or 2 GS/s when the EPR data are collected in a single-channel mode. By using high-speed flash ADCs, a pipelined 8-bit adder, and a 24-bit accumulator, a repetition rate of 230 kHz is realized to sum FIDs of 4096 points. The record length is programmable up to a maximum of 8K points and a large number of FIDs (224) can be summed without overflow before the data can be transferred to a host computer via GPIB interface for further processing. The data acquisition system can operate in a two-channel (quadrature) receiver mode for the conventional mixing to baseband. For detection using the single-channel mode, the resonance signals around the center frequency of 300 MHz were mixed with a synchronized local oscillator of appropriate frequency leading to an intermediate frequency (IF) which is sampled at a rate of 2 GS/s. Comparison of quadrature-mode and an IF-mode operation for EPR detection is presented by studying the FID signal intensity across a bandwidth of 10 MHz and as a function of transmit RF power. Imaging of large-sized phantoms accommodated in appropriately sized resonators indicates that IF-mode operation can be used to obtain distortion-free images in resonators of size 50 mm diameter and 50 mm length.

Time and frequency-resolved photoluminescence up conversion using broadly tuneable picosecond infrared pulses

A simultaneous time and frequency-resolved photoluminescence setup based upon the concept of sum-frequency generation has been developed using the parallel collection capabilities of a liquid nitrogen cooled, high quantum efficiency charge coupled device (CCD) detector. This up conversion system can provide excellent time resolution (down to ∼100 fs), when the detector is used in the single channel mode, with large dynamic range. When the CCD detector is used in its full capacity (1024 channels), wide spectral range as well as temporal information are obtained simultaneously from the up-converted signal, thus providing important information on the dynamics of various emission peaks which can occur simultaneously. Together with this, an efficient method for generation of high repetition rate, low energy infrared light between 1.44 and 1.62 μm is described. The technique uses difference frequency mixing of the fundamental wavelength of a mode-locked Nd:yttrium aluminum garnet laser and the output of a synchronously pumped Rhodamine 640 dye laser in a 10 mm long lithium triborate crystal. This source was then used to performed cw and time-resolved up-conversion photoluminescence measurements on a 1.54 μm emitting InGaAsP epitaxial layer.

Through the looking glass

The main distinctive feature in the creation of the new nuclear fuel handling complex at the Novovoronezh NPP is the deep integration of the information and control system (ICS) and the electrical equipment complex of the refueling machine (RM) into a single complex. The structure of the multi-level multi-processor and multi-network ICS provides high fault-tolerance and functional safety and fully corresponds to the principle of no single point of failure, even when operating in single-channel mode. Control of the RM during refueling is carried out with the participation of a human operator, who is supported by an intelligent interface. The operator makes decisions on certain actions to control the RM and the complex as a whole, monitors the control process and takes decisions on preventing abnormal or emergency situations.In fact, the ICS is a distributed system that implements the entire control cycle and contains information, processing and control parts. In each part, communication devices realize data connections between the components on the entire graph or on a common bus.The development result is a new generation RM ICS that differs from the existing ones by innovative methodical, algorithmic, hardware–software and design-technological solutions, which reduce the time and increase the safety of nuclear fuel handling in VVER reactors. At the same time, the introduction of the RM ICS increases the installed capacity utilization factor (ICUF) of the power unit by about 1.66%, which ensures additional electricity generation and supply for consumers.

Protein kinase C-mediated inhibition of an inward rectifier potassium channel by substance P in nucleus basalis neurons.

In nucleus basalis neurons, substance P (SP) causes a slow excitation, mediated through a pertussis toxin-insensitive G protein, by suppressing an inward rectifier K+ channel. Here we report that SP applied outside the patch pipette inhibited the single-channel activity, recorded on-cell, of the inward rectifier. The PKC inhibitors staurosporine and PKC(19-36) suppressed this effect in whole-cell mode and in on-cell single-channel mode. A diacylglycerol analog mimicked the SP effect, and PKC(19-36) suppressed this analog effect. SP irreversibly suppressed the inward rectifier in neurons treated with okadaic acid. These results indicate that a diffusible messenger mediates the SP effect, that its signal transduction involves phosphorylation by PKC, and that dephosphorylation by a serine/threonine protein phosphatase mediates its recovery.

Characterization and simulation of proton exchanged integrated optical modulators with various dielectric buffer layers

Fast and accurate numerical techniques are developed for calculating the optical depth of modulation of integrated optical devices with various dielectric buffer layers. The matrix effective refractive-index method is used in calculating the LiNbO/sub 3/ proton exchange single-channel optical mode parameters. An approximate technique for calculating electrode electric-field distributions as a function of various buffer layers is presented. Comparisons of computer simulations to experimental measurements performed on Mach-Zehnder modulators containing various buffer layers demonstrate that the numerical techniques are sufficiently accurate for computer-aided design use. >

An Element-Specific, Dual-Channel, Flame Infrared Emission, Gas Chromatography Detector for Chlorinated and Fluorinated Hydrocarbons

A flame infrared emission (FIRE) gas chromatography (GC) detector for organofluorine and organochlorine compounds has been developed and evaluated. The element-specific GC-FIRE detector makes use of a beamsplitter to divide the source radiation into two optical paths. The divided radiation passes through appropriate notch filters to isolate the background and analyte emission, which are each monitored by separate lead selenide detectors that form part of a Wheatstone bridge network. The output from the Wheatstone bridge is fed into the differential mode (A-B) input of a lock-in amplifier (LIA). In the chlorine mode of operation, a 3.7- μm optical notch filter is used in the analytical channel to isolate a portion of the HCl emission that results when organochlorine compounds are combusted in the hydrogen/air flame. In the fluorine mode of operation, a 2.35- μm optical notch filter in combination with a 2.55- μm short-pass filter is used to isolate a portion of the HF emission that results when organofluorine compounds are combusted. With the use of the dual-channel system, selectivity ratios of at least 760 (F) and 100 (Cl) were obtained, respresenting improvements by factors of about 104 (F) and 30 (Cl) in comparison with results from the single-channel mode of operation. With the use of Freon-113® (C2Cl3F3) as a representative analyte, detection limits in both the chlorine- and fluorine-selective modes were 200 ng s−1, representing improvements by factors of about 9.5 (F) and 4.5 (Cl), in comparison with results from the single-channel mode of operation.

Flow instabilities in parallel-channel flow systems of gas-liquid two-phase mixtures

Parallel-channel two-phase flow systems with compressible capacities and the negative-slope characteristics of the pressure drop vs flow rate curve suffer from a non-uniform flow distribution and/or pressure drop oscillation, depending on the pressure drop characteristics of each channel, under certain operating conditions. The modes of flow distribution are quite similar to those observed in boiling channels. Pressure drop oscillations are subdivided into two types: relaxation oscillation and quasi-static oscillation. The modes of oscillation observed in the parallel-channel system are a single-channel mode, a U-tube mode and a multi-channel mode. These modes of oscillation are closely related to the type of oscillation. Upstream compressibility in the gas feed pipe has a destabilizing effect on the oscillation. On the other hand, upstream compressibility in the liquid feed pipe has a stabilizing effect on the oscillations of the gas flow rate and the pressure drop between the headers of parallel channels, but induces a small oscillation of the liquid flow rate. These non-uniform flow distribution and oscillation patterns are analyzed; the results of the analysis are found to be in good agreement with the experimental results. Thus, the characteristics of the non-uniform flow distribution and the oscillation can be estimated by the method of analysis presented in this paper.

Single-channel versus multichannel electrical stimulation. Voicing-frequency and formant-transition difference limens.

The 'frequency' processing ability of 11 cochlear-implant patients wearing the Symbion device was evaluated with the stimuli presented in a multichannel mode and in a single-channel mode. A fixed-formant synthetic vowel /a/ was used to measure voicing-frequency difference limen. A voiced, synthetic single formant was used to measure the formant-transition difference limen. On the voicing-frequency test, patients obtained a median difference limen of 8 Hz when stimuli were presented in the multichannel mode and 14.7 Hz in the single-channel mode. On the formant-transition test, patients obtained a median difference limen of 589 Hz in the multichannel mode and 611 Hz in the single-channel mode. Three patients were unable to obtain a difference limen within the range of available stimuli. The performance with multichannel stimulation was significantly better (lower difference limen) than performance in the single channel stimulation. Temporal information in more channels and place information may contribute to the superior performance with multichannel stimulation.

Some remarks on discrete-time buffers with correlated arrivals

A discrete-time buffer system with infinite waiting room, one single output channel and synchronous transmission mode is treated. The arrivals are correlated and a first order Markov process is used to describe this correlation. A set of equations describing the behavior of such a system is derived. In general, these cannot be solved easily; in some interesting special cases, however, explicit expressions for the probability generating function of the buffer occupancy (in stochastic equilibrium) are obtained. Also a mean value analysis of buffer behavior that applies for a large class of arrival processes is presented.

Speciation of Arsenic and Cadmium Compounds by Reversed-Phase Ion-Pair LC with Single-Wavelength Inductively Coupled Plasma Detection

Inductively coupled plasma (ICP) is one of the most popular plasma sources for spectrochemical analysis involving both single-element and multielement determinations. The occurrence of spectral overlap interferences has been a problem with some samples in complex matrices. The selection of appropriate analytical lines may require some compromise between optimum detection limits and the least spectral interference from major concomitants. However, if potential interfering substances are separated in time, their determination within a single-wavelength window (channel) should be possible. The applicability of ICP detection combined with high pressure liquid chromatography (HPLC) for speciation plus time resolution appears to be an attractive and potentially valuable analytical tool. The use of single-channel detection with reversed-phase ion-pair LC to separate Cd and As compounds has been investigated in this work. Complex samples containing sodium arsenite, sodium arsenate, cadmium ethylenediaminetetraacetate, and cadmium nitrilotriacetate were separated by reversed-phase ion-pair LC and detected in the single-channel mode at 228.812 nm, one of the useful “arsenic” emission wavelengths. This enables Cd (228.802 nm) and As speciation and detection at one wavelength setting because, within this bandpass, emission from both Cd and As can be detected. The separation efficiency has been improved through development of suitable column materials and mobile phases. The present experiment also shows the advantage of the ICP as an element-specific and -selective detector when compared to a conventional UV detector. Discussion of the advantages and applicability of this single-channel technique is given in terms of simplicity, sensitivity, precision, and detection limits.

25 + 1 channel pulsed ultrasound Doppler velocity meter for quantitative flow measurements and turbulence analysis

A multichannel pulsed ultrasound Doppler instrument designed to measure velocity and volume flow rate quantitatively has been applied for turbulence detection. A 7-MHz transmitting frequency and a phase locked loop technique for the frequency to velocity conversion have been used to obtain high temporal resolution in the single channel mode. To provide for reliable positioning of the single gate within the arterial lumen the device could first be operated in the multichannel mode measuring the velocity profiles with zero crossing detection methods. Measurements of the velocity in the center of the lumen of the common and internal carotid arteries have been recorded on a beat to beat basis. An ensemble average of 16 consecutive pulses was determined. Thereafter, the root mean square of the differences between ensemble average and individual velocity pulses was computed, and a disturbance index was defined by dividing the disturbance velocity by the mean velocity. First clinical results show that the method presented is a valuable complement to the analysis of flow pulse patterns in the transcutaneous examination of carotid arteries.