Gas viscosity measurement with diamagnetic-levitation viscometer based on electromagnetically spinning system
Utilizing a graphite-disk probe attached with a thinaluminum disk, we have developed a friction-freeviscosity measurement system. The probe is levitated above a NdFeB magnet because ofdiamagnetic effect and rotated by an electromagnetically inducedtorque. The probe is absolutely free form mechanicalfriction, and therefore, the accuratemeasurements of theviscosity of gases can be achieved. To demonstrate the accuracy and sensitivity of our method, wemeasured theviscosity of 8 kinds of gases and its temperature change from 278 K to 318 K, and we confirmed a good agreement between the obtained values and literature values. Th...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: Y. Shimokawa, Y. Matsuura, T. Hirano and K. Sakai Source Type: research
An ultra-low noise, high-voltage piezo-driver
We present an ultra-lownoise, high-voltage driver suited for use withpiezoelectric actuators and other low-current applications. The architecture uses a flyback switching regulator to generate up to 250 V in our current design, with an output of 1 kV or more possible with small modifications. A high slew-rate op-amp suppresses the residual switchingnoise, yielding a total root-mean-squarenoise of ≈100μV (1 Hz –100 kHz). A low-voltage (±10 V), high bandwidth signal can be summed with unity gain directly onto the output, making the driver well-suited for closed-loop feedback applications. Digital control enables both r...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: N. C. Pisenti, A. Restelli, B. J. Reschovsky, D. S. Barker and G. K. Campbell Source Type: research
Seeking maximum linearity of transfer functions
Linearity is an important and frequently sought property in electronics and instrumentation. Here, we report a method capable of, given a transfer function (theoretical or derived from some realsystem), identifying the respective most linear region of operation with a fixed width. This methodology, which is based on least squares regression and systematic consideration of all possible regions, has been illustrated with respect to both an analytical (sigmoid transfer function) and a simple situation involving experimental data of a low-power, one-stage class Atransistor current amplifier. Such an approach, which has been ad...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: Filipi N. Silva, Cesar H. Comin and Luciano da F. Costa Source Type: research
Development of array piezoelectric fingers towards in vivo breast tumor detection
We have investigated the development of a handheld 4 × 1piezoelectric finger (PEF) array breasttumor detector system towardsin vivo patienttesting, particularly, on how the duration of the DC applied voltage, the depression depth of the handheld unit, and breast density affect the PEF detection sensitivity on 40 patients. The tests were blinded and carried out in four phases: with DC voltage durations 5, 3, 2, to 0.8 s corresponding to scanning a quadrant, a half, a whole breast, and both breasts within 30 min, respectively. The results showed that PEF detection sensitivity was unaffected by shortening the applied vo...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: Xin Xu, Youngsoo Chung, Ari D. Brooks, Wei-Heng Shih and Wan Y. Shih Source Type: research
Composition-tuning in a solid-state electrotransport furnace with active thermal expansion compensation
A new solid-state electrotransport (SSE) apparatus for refining ultra-puresingle crystals of metallic compounds under ultra-high vacuum is described. The setup employs a novelthermal expansion compensation mechanism to minimize mechanical stress on the sample during refinement with cold clamps for contamination-less purification at elevated temperatures. The apparatus is designed to tune the composition of initially slightly off-stoichiometric samples. Theexpansion compensation and stress-free operation were tested by recording thethermal expansion of elemental cerium in a treatment up to 655 °C. SSE refinement was the...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: J. L. Schmehr, W. Whitley and A. D. Huxley Source Type: research
High repetition pump-and-probe photoemission spectroscopy based on a compact fiber laser system
The paper describes atime-resolvedphotoemission (TRPES) apparatus equipped with a Yb-dopedfiber laser system delivering 1.2-eV pump and 5.9-eV probe pulses at the repetition rate of 95 MHz. Time and energy resolutions are 11.3 meV and ∼310 fs, respectively, the latter is estimated by performing TRPES on a highly oriented pyrolyticgraphite (HOPG). The high repetition rate is suited for achieving high signal-to-noise ratio in TRPES spectra, thereby facilitating investigations of ultrafast electronic dynamics in the low pump fluence (p) region. TRPES ofpolycrystalline bismuth (Bi) atp as low as 30 nJ/mm2 is demonstrated. Th...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: Y. Ishida, T. Otsu, A. Ozawa, K. Yaji, S. Tani, S. Shin and Y. Kobayashi Source Type: research
A sparsity-based iterative algorithm for reconstruction of micro-CT images from highly undersampled projection datasets obtained with a synchrotron X-ray source
SynchrotronX-ray MicroComputed Tomography (Micro-CT) is animaging technique which is increasingly used for non-invasivein vivo preclinicalimaging. However, it often requires a large number of projections from many different angles toreconstruct high-qualityimages leading to significantly highradiationdoses and long scan times. To utilize thisimaging technique further forin vivoimaging, we need to designreconstruction algorithms that reduce theradiationdose and scan time without reduction ofreconstructed image quality. This research is focused on using a combination of gradient-based Douglas-Rachford splitting and discretew...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: S. Ali Melli, Khan A. Wahid, Paul Babyn, David M. L. Cooper and Varun P. Gopi Source Type: research
Retarding field analyzer for the EAST plasma boundary
A novel bi-directional Retarding Field Analyzer(RFA) probe has been installed on a fast reciprocating drive system on the Experimental Advanced SuperconductingTokamak (EAST) tomeasure the iontemperature and fast electron fluxes. ALangmuir probe assembly was added on the top of theRFA head to control theRFA position relative to the last closed flux surface and to have a possibility tomeasure the electron density andtemperature as well. Except the iontemperature, the fast electron fluxes from both ion and electron drift sides have beenmeasured during lower hybrid current drive. TheRFA probe has been also used tomeasure the f...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: Y. L. Li, G. S. Xu, C. Xiao, H. Q. Wang, N. Yan, B. N. Wan, L. Chen, Y. L. Liu, H. Zhang, W. Zhang, L. Wang, G. H. Hu, R. Chen, J. C. Xu, Y. Ye and J. Li Source Type: research
Bench testing of a heterodyne CO2 laser dispersion interferometer for high temporal resolution plasma density measurements
Aheterodyne detection scheme is combined with a 10.59 μm CO2 laserdispersioninterferometer for the first time to allow large bandwidthmeasurements in the 10-100 MHz range. The approach employed utilizes a 40 MHz acousto-optic cell operating on the frequency doubled CO2 beam which is obtained using a high 2nd harmonic conversion efficiency orientation patterned gallium arsenide crystal. Themeasured standard deviation of the line integratedelectron density equivalent phase resolution obtained with digital phase demodulation technique, is 4 × 1017 m−2. Air flow was found to significantly affect the baseline of the phase s...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: T. Akiyama, M. A. Van Zeeland, R. L. Boivin, T. N. Carlstrom, J. A. Chavez, C. M. Muscatello, R. C. O ’Neill, J. Vasquez, M. Watkins, W. Martin, A. Colio, D. K. Finkenthal, D. L. Brower, J. Chen, W. X. Ding and M. Perry Source Type: research
Modulation axis performs circular motion in a 45 ° dual-drive symmetric photoelastic modulator
A 45 ° dual-drive symmetric photoelasticmodulator is demonstrated. Twopiezoelectric actuators are connected to a symmetric photoelastic crystal at an angle of 45 °. When the amplitudes of the stress standingwaves induced by the twopiezoelectric actuators are equal and the phase difference between the two stress standingwaves isπ2, the modulation axis performs circular motion with a frequency of half of the photoelastic modulator ’s resonant frequency, while the retardation remains a constant that is determined at the driving voltage amplitudes. This reveals a newpolarization modulation method. We have theoretically an...
Source: Review of Scientific Instruments - December 8, 2016 Category: Physics Authors: K. W. Li, L. M. Wang, R. Zhang and Z. B. Wang Source Type: research
Note: On the choice of the appropriate excitation-pulse-length for assessment of slow luminescence decays
The decay-time distribution deduced from luminescence kinetics experiments is, in general, dependent on the excitation pulse length as a direct consequence of different onset dynamics. We demonstrate this effect for the case of square excitation pulses applied to study the luminescence kinetics in Sinanocrystals. The short- and long-pulse limits are defined as 0.1 times the shortest lifetime in the distribution and 3 times the longest time, respectively. Outside these limits the decay-time distribution is independent on the pulse duration. In addition, we describe experimental conditions required to obtain a correct depict...
Source: Review of Scientific Instruments - December 7, 2016 Category: Physics Authors: M. Greben and J. Valenta Source Type: research
Apparatus for measuring pressure-driven transport through channels at high Knudsen numbers
The pressure-driven gasflow through micro- and nano-porousstructures is particularly interesting for innovativetechnologies such asmicroelectromechanical and nano-mechanical-electricalsystems. The classical continuum assumption breaks down for rarefiedflow through channels with a characteristic dimension comparable to the mean free path of the gas.Theories based on molecular interactions have been formulated to predict theflow at high Knudsen numbers.Measuring rarefied gasflow experimentally is a challenge since only a few studies have been able to determine flowrates in the molecularflow regime. Here we present the design...
Source: Review of Scientific Instruments - December 7, 2016 Category: Physics Authors: S. Karakitsiou, B. Holst and A. C. Hoffmann Source Type: research
Design of an accurate wireless data logger for vibration analysis with Android interface
In this work a new accurate wireless data logger using the Androidinterface was developed to monitor vibrations at low-cost. The new data logger is completely autonomous and extremely reduced in size. This instrument enables data collection wirelessly and the ability to display it on any tablet or smartphone with operating system Android. The prototype allows the monitoring of any industrial system with minimal investment in material and installation costs. The data logger is capable of making 12.8 kSPS enough to sample up to 5 kHz signals. The basic specification of the data logger includes a high resolution 1-axispiezoel...
Source: Review of Scientific Instruments - December 7, 2016 Category: Physics Authors: J. R. Blanco, J. Men éndez, F. J. Ferrero, J. C. Campo and M. Valledor Source Type: research
Photonic crystal fiber modal interferometer with Pd/WO3 coating for real-time monitoring of dissolved hydrogen concentration in transformer oil
A highly-sensitive and temperature-robustphotonic crystal fiber(PCF) modalinterferometer coated with Pd/WO3film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. Thesensor probe was fabricated by splicing two segments of a single mode fiber(SMF) with both ends of thePCF. Since the collapse of air holes in thePCF in the interfaces betweenSMF andPCF, a SMF-PCF-SMFinterferometer structure was formed. The Pd/WO3film was fabricated by sol-gel method and coated on the surface of thePCF by dip-coating method. When the Pd/WO3film is exposed to hydrogen, both the len...
Source: Review of Scientific Instruments - December 7, 2016 Category: Physics Authors: Ya-nan Zhang, Qilu Wu, Huijie Peng and Yong Zhao Source Type: research
A new method for simultaneous measurement of Seebeck coefficient and resistivity
A new method has been proposed and verified tomeasure the Seebeck coefficient andelectrical resistivity of a sample in the paper. Different from the conventional method for Seebeck coefficient andresistivitymeasurement, the new method adopts a four-point configuration tomeasure both the Seebeck coefficient andresistivity. It can well identify the inhomogeneity of the sample by simply comparing the four Seebeck coefficients of different probe combinations, and it is more accurate and appropriate to take the average value of the four Seebeck coefficients as themeasured result of the Seebeck coefficient of the sample than tha...
Source: Review of Scientific Instruments - December 6, 2016 Category: Physics Authors: Xu He, Junyou Yang, Qinghui Jiang, Yubo Luo, Dan Zhang, Zhiwei Zhou, Yangyang Ren, Xin Li, Jiwu Xin and Jingdi Hou Source Type: research
