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Dec 2007

Volume 78, Issue 12, Articles (12xxxx)

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Rev. Sci. Instrum. 78, 121301 (2007); http://dx.doi.org/10.1063/1.2821148 (15 pages)

A. Westphalen, M.-S. Lee, A. Remhof, and H. Zabel
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A high pressure cell for small angle neutron scattering up to 500 MPa in combination with light scattering to investigate liquid samples

J. Kohlbrecher, A. Bollhalder, R. Vavrin, and G. Meier

Rev. Sci. Instrum. 78, 125101 (2007); http://dx.doi.org/10.1063/1.2817632 (6 pages) | Cited 9 times

Online Publication Date: 6 December 2007

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We report on a high pressure cell to use with small angle neutron scattering (SANS) in a pressure range up to 500 MPa. The cell offers the new possibility to investigate liquid samples by a specially designed sample chamber, which allows changing of samples relatively easily. Since the cell construction uses sapphire as window material, also light scattering investigations can be performed simultaneously to the SANS measurements. In this article we describe the construction of a high pressure cell and we demonstrate the applicability of the construction for SANS in combination with dynamic light scattering showing data on the biological molecule lysozyme.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Design and implementation of an efficient acoustically levitated drop reactor for in stillo measurements

Christopher R. Field and Alexander Scheeline

Rev. Sci. Instrum. 78, 125102 (2007); http://dx.doi.org/10.1063/1.2818798 (8 pages) | Cited 11 times

Online Publication Date: 6 December 2007

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We present the details necessary for building an efficient acoustic drop levitator with reduced electrical power consumption and greater drop stability compared to previous designs. The system is optimized so that the levitated drop may be used as a chemical reactor. By introducing a temperature, pressure, and relative humidity sensor for feedback control of a linear actuator for adjusting resonator length, we have built a completely automated system capable of continuous levitation for extended periods of time. The result is a system capable of portable operation and interfacing with a variety of detection instrumentation for in stillo (in drop) measurements.
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43.58.-e Acoustical measurements and instrumentation

A study on the disk-shaped piezoelectric transformer with multiple outputs

Mingsen Guo, K. H. Lam, S. Wang, K. W. Kwok, Helen L. W. Chan, and X. Z. Zhao

Rev. Sci. Instrum. 78, 125103 (2007); http://dx.doi.org/10.1063/1.2818809 (7 pages)

Online Publication Date: 7 December 2007

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In this study, a modified disk-shaped multiple-output piezoelectric transformer operated at the fundamental radial vibration mode has been presented. A derived equivalent circuit for the multioutput piezoelectric transformer was used to analyze the performance. Two piezoelectric transformers, a symmetrically electroded piezoelectric transformer with dual outputs and an asymmetrically electroded piezoelectric transformer with triple outputs, were fabricated with lead zirconate titanate piezoelectric ceramics. The characteristics of the two piezoelectric transformers were investigated experimentally. The piezoelectric transformer with multiple outputs has potential to be used in power supply units and other electronic circuits.
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85.50.-n Dielectric, ferroelectric, and piezoelectric devices
84.30.Jc Power electronics; power supply circuits

High-pressure phase equilibria with compressed gases

Wei Ren and Aaron M. Scurto

Rev. Sci. Instrum. 78, 125104 (2007); http://dx.doi.org/10.1063/1.2814025 (7 pages) | Cited 14 times

Online Publication Date: 13 December 2007

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An apparatus is described that is capable of determining high-pressure vapor-liquid equilibrium, liquid-liquid equilibrium, solid-liquid-vapor equilibrium, vapor-liquid-liquid equilibrium, and mixture critical points and transitions. The device is capable of temperatures to 150 °C and pressures to 300 bars (higher with slight modifications). The construction and operation are described in detail and do not require the use of mercury. This method requires very low sample volumes and no analytical equipment nor system-specific calibration. The apparatus was verified by comparison with literature data for the decane-CO2 mixture and CO2-ionic liquid [1-hexyl-3-methyl-imidazolium bis(trifyl)imide)] systems. The experimental data have excellent agreement with the literature data that used different experimental methods. A rigorous error analysis of the system is also presented.
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64.70.Ja Liquid-liquid transitions
62.50.-p High-pressure effects in solids and liquids
64.70.D- Solid-liquid transitions
64.70.F- Liquid-vapor transitions
64.75.-g Phase equilibria

A probe for in situ, remote, detection of defects in buried plastic natural gas pipelines

M. P. Mathur, J. L. Spenik, C. M. Condon, E. R. Monazam, and W. L. Fincham

Rev. Sci. Instrum. 78, 125105 (2007); http://dx.doi.org/10.1063/1.2821238 (5 pages)

Online Publication Date: 18 December 2007

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Several techniques are available to determine the integrity of in situ metal pipeline but very little is available in the literature to determine the integrity of plastic pipelines. Since the decade of the 1970s much of the newly installed gas distribution and transmission lines in the United States are fabricated from polyethylene or other plastic. A probe has been developed to determine the in situ integrity of plastic natural gas pipelines that can be installed on a traversing mechanism (pig) to detect abnormalities in the walls of the plastic natural gas pipeline from the interior. This probe has its own internal power source and can be deployed into existing natural gas supply lines. Utilizing the capacitance parameter, the probe inspects the pipe for flaws and records the data internally which can be retrieved later for analysis.
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89.20.Bb Industrial and technological research and development

Pressure measurements in laboratory-scale blast wave flow fields

S. Rahman, E. Timofeev, and H. Kleine

Rev. Sci. Instrum. 78, 125106 (2007); http://dx.doi.org/10.1063/1.2818807 (11 pages) | Cited 2 times

Online Publication Date: 20 December 2007

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The present study examines the effects that temporal and spatial averagings due to finite size and finite response time of pressure transducers have on the pressure measurements in blast wave flow fields generated by milligram charges of silver azide. In such applications, the characteristic time and length scales of the physical process are of the same order of magnitude as the temporal and spatial characteristics of the transducer. The measured pressure values will then be spatially and temporally averaged, and important parameters for the assessment of blast effects may not be properly represented in the measured trace. In this study, face-on and side-on pressure transducer setups are considered. In the experiments, face-on and side-on readings at the same distance from the charge as well as time-resolved optical visualization of the whole flow field are obtained simultaneously for the same explosive event. The procedure of data extraction from the experimental pressure traces is revisited and discussed in detail. In the numerical modeling part of the study, numerical blast flow fields are generated using an Euler flow solver. A numerical pressure transducer model is developed to qualitatively simulate the averaging effects. The experimental and numerical data show that the results of pressure measurements in experiments with small charges must be used with great caution. The effective averaging of the pressure signal may lead to a significant underestimation of blast wave intensities. The side-on setup is especially prone to this effect. The face-on setup provides results close to those obtained from optical records only if the pressure transducer is sufficiently remote from the charge.
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47.40.Rs Detonation waves
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
47.80.Fg Pressure and temperature measurements
07.07.Mp Transducers

The influence of preamplifiers on the piezoelectric sensor’s dynamic property

W. Q. Liu, Z. H. Feng, R. B. Liu, and J. Zhang

Rev. Sci. Instrum. 78, 125107 (2007); http://dx.doi.org/10.1063/1.2825404 (4 pages) | Cited 1 time

Online Publication Date: 26 December 2007

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A charge amplifier or a voltage amplifier can be used as a signal conditioning circuit between a piezoelectric element and a meter or a data acquisition board. The outputs of the piezoelectric sensor are in an open-circuit state and a short-circuit state if a voltage amplifier and a charge amplifier are used, respectively. When the electrodes are in different states, the piezoelectric element has rather different stiffness and thus different sensor resonant frequency. This phenomenon is theoretically analyzed in detail and validated by a carefully designed experiment. The results indicate that a much wider range of working frequency is achieved when a voltage amplifier is used.
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43.38.Fx Piezoelectric and ferroelectric transducers
77.65.-j Piezoelectricity and electromechanical effects
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