RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue

Dec 2004

Volume 75, Issue 12, pp. 5079-5369

Return to All Sections
back to top
RSS Feeds
back to top GENERAL INSTRUMENTS

A simple noise subtraction technique

F. Douarche, L. Buisson, S. Ciliberto, and A. Petrosyan

Rev. Sci. Instrum. 75, 5084 (2004); http://dx.doi.org/10.1063/1.1821625 (6 pages) | Cited 6 times

Online Publication Date: 10 November 2004

Full Text: | Download PDF

Show Abstract
Measuring very low level signals at low frequency is a tedious task, because environmental noise increases in this frequency domain and it is very difficult to filter it efficiently. In order to counteract these major problems, we propose a simple and generic noise subtraction technique, which mixes several features of traditional feedback techniques and those of noise estimators. As an example of application, large band measurements of the thermal fluctuations of a mechanical oscillator are presented. Our results show that the proposed noise subtraction technique is easy to implement and gives good results.
Show PACS
84.40.Ua Telecommunications: signal transmission and processing; communication satellites

Optimal two-point static calibration of measurement systems with quadratic response

Ramon Pallàs-Areny, Josep Jordana, and Óscar Casas

Rev. Sci. Instrum. 75, 5106 (2004); http://dx.doi.org/10.1063/1.1818531 (6 pages)

Online Publication Date: 10 November 2004

Full Text: | Download PDF

Show Abstract
Measurement devices and instruments must be calibrated after manufacture to correct for component and assembly tolerances, and periodically to correct for drift and aging effects. The number of reference inputs needed for calibration depends on the actual transfer characteristic and the desired accuracy. Often, a linear characteristic is assumed for simplicity, either for the overall input range (global linearization) or for successive input subranges (piecewise linearization). Thus, only two reference inputs are needed for each straight line. This two-point static calibration can be easily implemented in any system having some basic computation capability and allows for the correction of zero and gain errors, and of their drifts if the system is periodically calibrated. Often, the reference inputs for that calibration are the end values of the measurement range (or subrange). However, this is not always the optimal selection because the calibration error is minimal for those reference inputs only, which are not necessarily the most relevant inputs for the system being considered. This article proposes three optimization criteria for the selection of calibration points: limiting the maximal error (LME), minimizing the integral square error (ISE), and minimizing the integral absolute error (IAE). Each of these criteria needs reference inputs whose values are symmetrical with respect to the midrange input (xc), have the form xc±Δx/(2√n) when the measurand has a uniform probability distribution function, Δx being the measurement span, and do not depend on the nonlinearity of the actual response, provided this is quadratic. The factor n depends on the particular criterion selected: n = 2 for LME, n = 3 for ISE, and n = 4 for IAE. These three criteria give parallel calibration lines and can also be applied to other nonlinear responses by dividing the measurement span into convenient intervals. The application of those criteria to the linearization of a type-J thermocouple illustrate their performance and advantages with respect to the customary end-point linearization (n = 1) even for nonquadratic responses. For quadratic responses, n = 1 yields the maximal error at the center of the input measurement range.
Show PACS
06.20.Dk Measurement and error theory
06.20.F- Units and standards
02.50.-r Probability theory, stochastic processes, and statistics

A device to investigate the axial strain dependence of the critical current density in superconductors

A. Godeke, M. Dhalle, A. Morelli, L. Stobbelaar, H. van Weeren, H. J. N. van Eck, W. Abbas, A. Nijhuis, A. den Ouden, and B. ten Haken

Rev. Sci. Instrum. 75, 5112 (2004); http://dx.doi.org/10.1063/1.1819384 (7 pages) | Cited 28 times

Online Publication Date: 10 November 2004

Full Text: | Download PDF

Show Abstract
We have developed an instrument to study the behavior of the critical current density (Jc) in superconducting wires and tapes as a function of field (μ0H), temperature (T), and axial applied strain (εa). The apparatus is an improvement of similar devices that have been successfully used in our institute for over a decade. It encompasses specific advantages such as a simple sample layout, a well defined and homogeneous strain application, the possibility of investigating large compressive strains and the option of simple temperature variation, while improving the main drawback in our previous systems by increasing the investigated sample length by approximately a factor of 10. The increase in length is achieved via a design change from a straight beam section to an initially curved beam, placed perpendicular to the applied field axis in the limited diameter of a high field magnet bore. This article describes in detail the mechanical design of the device and its calibrations. Additionally initial Jc(εa) data, measured at liquid helium temperature, are presented for a bronze processed and for a powder-in-tube Nb3Sn superconducting wire. Comparisons are made with earlier characterizations, indicating consistent behavior of the instrument. The improved voltage resolution, resulting from the increased sample length, enables Jc determinations at an electric field criterion Ec = 10 μV/m, which is substantially lower than a criterion of Ec = 100 μV/m which was possible in our previous systems.
Show PACS
84.71.Mn Superconducting wires, fibers, and tapes
74.25.Sv Critical currents
07.10.Pz Instruments for strain, force, and torque
74.25.Ld Mechanical and acoustical properties, elasticity, and ultrasonic attenuation
02.70.Dh Finite-element and Galerkin methods

Heat power source controller circuit

F. Madrid, X. Jordà, M. Vellvehi, X. Perpiñà, and P. Godignon

Rev. Sci. Instrum. 75, 5123 (2004); http://dx.doi.org/10.1063/1.1819451 (3 pages)

Online Publication Date: 10 November 2004

Full Text: | Download PDF

Show Abstract
Experimental works on thermal management of electronic systems, such as thermal resistance or thermal conductivity measurement, often require a controlled heat power source. This article proposes a circuit based on an integral automatic controller that sets a heat power dissipation level of a power metal-oxide-semiconductor field effect transistor used as a heating device. It can operate in dc mode, setting a steady power generation, and in pulsed mode, controlling a transient power wave form. The controller operation principle is established together with all details for its implementation and use.
Show PACS
85.30.Tv Field effect devices

Threshold-crossing counting technique for damping factor determination of resonator sensors

Kefeng Zeng and Craig A. Grimes

Rev. Sci. Instrum. 75, 5257 (2004); http://dx.doi.org/10.1063/1.1819631 (5 pages) | Cited 4 times

Online Publication Date: 15 November 2004

Full Text: | Download PDF

Show Abstract
The behavior of resonator-type sensors at resonance is characterized by two fundamental parameters: resonance frequency and damping factor (or Q-factor). Practical applications require accurate and efficient measurements of these two parameters. Using magnetoelastic resonant sensors as a test case earlier work [K. Zeng, K. G. Ong, C. Mungle, and C. A. Grimes, Rev. Sci. Instrum. 73, 4375 (2002)] demonstrated the ability to determine resonance frequency by counting the number of cycles in the transient response of a pulsewise excited sensor. Presented in this paper is a novel technique for measuring the damping factor of a resonant magnetoelastic sensor, or any resonator type sensor, using threshold-crossing counting of the transient response. The damping factor determination technique eliminates the need for a lock-in amplifier or FFT analysis as in the conventional method of quality factor estimation from spectrum analysis, significantly simplifying the electronic implementation as well as improving measurement speed and accuracy.
Show PACS
07.55.-w Magnetic instruments and components
85.70.Ec Magnetostrictive, magnetoacoustic, and magnetostatic devices

Dedicated Max-Planck beamline for the in situ investigation of interfaces and thin films

A. Stierle, A. Steinhäuser, A. Rühm, F. U. Renner, R. Weigel, N. Kasper, and H. Dosch

Rev. Sci. Instrum. 75, 5302 (2004); http://dx.doi.org/10.1063/1.1819552 (6 pages) | Cited 29 times

Online Publication Date: 17 November 2004

Full Text: | Download PDF

Show Abstract
A dedicated beamline for the Max-Planck-Institut für Metallforschung was recently taken into operation at the Ångstrømquelle Karlsruhe (ANKA). Here we describe the layout of the beamline optics and the experimental end-station, consisting of a heavy duty multiple circle diffractometer. For both a new design was realized, combining a maximum flexibility in the beam properties [white, pink, (focused) monochromatic, energy range 6–20 keV] with a special diffractometer for heavy sample environments up to 500 kg, that can be run in different geometrical modes. In addition the angular-reciprocal space transformations for the diffractometer in use are derived, which allows an operation of the instrument in the convenient six circle mode. As an example, results from surface x-ray diffraction on a Cu3Au(111) single crystal are presented.
Show PACS
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
42.25.Fx Diffraction and scattering

Multi-mode combustion facility for thermal treatment studies of wastes and biomass

Fadi Eldabbagh, Janusz A. Kozinski, Michael Bourassa, Jean-Pierre Farant, Peter Gangli, Michael Groves, Eric Rosen, Vic Uloth, Jalal Hawari, and Wes Hutny

Rev. Sci. Instrum. 75, 5308 (2004); http://dx.doi.org/10.1063/1.1821645 (7 pages) | Cited 1 time

Online Publication Date: 30 November 2004

Full Text: | Download PDF

Show Abstract
This article describes newly built Multi-Mode Combustion Facility (MCF) used for investigating thermal destruction of industrial wastes and combustion of biomass. A flexible, refractory-lined combustion chamber consists of individual sections of various heights and diameter of 0.5 m. The MCF can be used either as a fluidized bed combustor (FBC) to study the combustion of solid residues or as a single-burner furnace (SBF) to study cofiring of biomass and natural gas. The facility is designed such that the outer wall temperature should not exceed 327 K with the use of water-cooling system and refractory materials. The inner temperature of each section is independent of the rest of the sections and controlled individually. This arrangement allows for the combustion process to be carried out in a multizone manner called low–high–low (LHL) temperature approach. The LHL approach means that the waste/biomass is initially fed into a low temperature zone (<1060 K) and then subjected to the high temperature treatment ( ∼ 1500 K) that is followed by another low temperature zone (<1160 K). The LHL setup allows for heavy metals encapsulation and immobilization within the fly ash particles. The facility has 25 openings for sampling of solids and gases at different stages of the combustion process, as well as in situ observation. Experiments reported in this article were performed in the bubbling FBC mode with the purpose of testing the leachability of heavy metals (Cd, Cr, and Pb) from fly ash generated during two different combustion approaches: (1) multi-zone LHL treatment, and (2) no-LHL. Baseline fluidization properties of different bed materials were tested. Axial profiles of temperature and gas concentration (CO2, NO, and NOx) were compared. The results show that the leachability of the heavy metals (Cd, Cr, and Pb) contained in the LHL-generated ash particles was negligible (0.14, 0.061, and 1.55 ppm, respectively), while the leachability data from the no-LHL technique were 30.7, 14.3, and 0.647 ppm, respectively. It was concluded that the MCF facility is easy to operate, flexible, and useful for studies of various waste-to-energy options. Our results also show an improvement in heavy metals leachability when using the LHL combustion technique.
Show PACS
82.33.Vx Reactions in flames, combustion, and explosions
81.40.Gh Other heat and thermomechanical treatments
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close