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Review of Scientific Instruments

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https://www.readbyqxmd.com/read/28040985/piezoresistive-strain-sensing-of-carbon-black-silicone-composites-above-percolation-threshold
#1
Shuying Shang, Yujuan Yue, Xiaoer Wang
A series of flexible composites with a carbon black (CB) filled silicone rubber matrix were made by an improved process in this work. A low percolation threshold with a mass ratio of 2.99% CB was achieved. The piezoresistive behavior of CB/silicone composites above the critical value, with the mass ratio of carbon black to the silicone rubber ranging from 0.01 to 0.2, was studied. The piezoresistive behavior was different from each other for the composites with different CB contents. But, the composites show an excellent repeatability of piezoresistivity under cyclic compression, no matter with low filler content or with high filler content...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040984/rugged-constant-temperature-thermal-anemometer
#2
J Palma, R Labbé
Here we report a robust thermal anemometer which can be easily built. It was conceived to measure outdoor wind speeds and for airspeed monitoring in wind tunnels and other indoor uses. It works at a constant, low temperature of approximately 90 °C, so that an independent measurement of the air temperature is required to give a correct speed reading. Despite the size and high thermal inertia of the probe, the test results show that this anemometer is capable of measuring turbulent fluctuations up to ∼100 Hz in winds of ∼14 m/s, which corresponds to a scale similar to the length of the probe...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040983/a-versatile-implementation-of-pulsed-optical-excitation-in-scanning-tunneling-microscopy
#3
P Kloth, T Thias, O Bunjes, J von der Haar, M Wenderoth
We present a combination of pulsed optical excitation and scanning tunneling microscopy with a highly flexible pulse generation method. A high frequency arbitrary wave generator drives a gigahertz electro-optical modulator, which processes a continuous-wave laser beam of a low-noise laser diode into the desired wave shape. For pump-probe excitation we generate optical pulse series in an all-electronic way. Thereby we can easily adapt parameters like pulse amplitude, width, or repetition cycle to the demands of the experiment...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040982/design-of-experimental-setup-for-supercritical-co2-jet-under-high-ambient-pressure-conditions
#4
Huaizhong Shi, Gensheng Li, Zhenguo He, Haizhu Wang, Shikun Zhang
With the commercial extraction of hydrocarbons in shale and tight reservoirs, efficient methods are needed to accelerate developing process. Supercritical CO2 (SC-CO2) jet has been considered as a potential way due to its unique fluid properties. In this article, a new setup is designed for laboratory experiment to research the SC-CO2 jet's characteristics in different jet temperatures, pressures, standoff distances, ambient pressures, etc. The setup is composed of five modules, including SC-CO2 generation system, pure SC-CO2 jet system, abrasive SC-CO2 jet system, CO2 recovery system, and data acquisition system...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040981/fabrication-of-thermal-resistant-gratings-for-high-temperature-measurements-using-geometric-phase-analysis
#5
Q Zhang, Z Liu, H Xie, K Ma, L Wu
Grating fabrication techniques are crucial to the success of grating-based deformation measurement methods because the quality of the grating will directly affect the measurement results. Deformation measurements at high temperatures entail heating and, perhaps, oxidize the grating. The contrast of the grating lines may change during the heating process. Thus, the thermal-resistant capability of the grating becomes a point of great concern before taking measurements. This study proposes a method that combines a laser-engraving technique with the processes of particle spraying and sintering for fabricating thermal-resistant gratings...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040980/curved-diamond-crystal-spectrographs-for-x-ray-free-electron-laser-noninvasive-diagnostics
#6
Sergey Terentyev, Vladimir Blank, Tomasz Kolodziej, Yuri Shvyd'ko
We report on the manufacturing and X-ray tests of bent diamond-crystal X-ray spectrographs, designed for noninvasive diagnostics of the X-ray free-electron laser (XFEL) spectra in the spectral range from 5 to 15 keV. The key component is a curved, 20-μm thin, single crystalline diamond triangular plate in the (110) orientation. The radius of curvature can be varied between R = 0.6 m and R = 0.1 m in a controlled fashion, ensuring imaging in a spectral window of up to 60 eV for ≃8 keV X-rays. All of the components of the bending mechanism (about 10 parts) are manufactured from diamond, thus ensuring safe operations in intense XFEL beams...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040979/opto-electro-modulated-transient-photovoltage-and-photocurrent-system-for-investigation-of-charge-transport-and-recombination-in-solar-cells
#7
Jiangjian Shi, Dongmei Li, Yanhong Luo, Huijue Wu, Qingbo Meng
An opto-electro-modulated transient photovoltage/photocurrent system has been developed to probe microscopic charge processes of a solar cell in its adjustable operating conditions. The reliability of this system is carefully determined by electric circuit simulations and experimental measurements. Using this system, the charge transport, recombination and storage properties of a conventional multicrystalline silicon solar cell under different steady-state bias voltages, and light illumination intensities are investigated...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040978/a-new-method-to-calibrate-the-absolute-sensitivity-of-a-soft-x-ray-streak-camera
#8
Jian Yu, Shenye Liu, Jin Li, Zhiwen Yang, Ming Chen, Luting Guo, Li Yao, Shali Xiao
In this paper, we introduce a new method to calibrate the absolute sensitivity of a soft X-ray streak camera (SXRSC). The calibrations are done in the static mode by using a small laser-produced X-ray source. A calibrated X-ray CCD is used as a secondary standard detector to monitor the X-ray source intensity. In addition, two sets of holographic flat-field grating spectrometers are chosen as the spectral discrimination systems of the SXRSC and the X-ray CCD. The absolute sensitivity of the SXRSC is obtained by comparing the signal counts of the SXRSC to the output counts of the X-ray CCD...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040977/modulation-axis-performs-circular-motion-in-a-45%C3%A2-dual-drive-symmetric-photoelastic-modulator
#9
K W Li, L M Wang, R Zhang, Z B Wang
A 45° dual-drive symmetric photoelastic modulator is demonstrated. Two piezoelectric actuators are connected to a symmetric photoelastic crystal at an angle of 45°. When the amplitudes of the stress standing waves induced by the two piezoelectric actuators are equal and the phase difference between the two stress standing waves is π2, 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...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040976/composition-tuning-in-a-solid-state-electrotransport-furnace-with-active-thermal-expansion-compensation
#10
J L Schmehr, W Whitley, A D Huxley
A new solid-state electrotransport (SSE) apparatus for refining ultra-pure single crystals of metallic compounds under ultra-high vacuum is described. The setup employs a novel thermal 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. The expansion compensation and stress-free operation were tested by recording the thermal expansion of elemental cerium in a treatment up to 655 °C...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040975/development-of-plasma-assisted-thermal-vapor-deposition-technique-for-high-quality-thin-film
#11
Kang-Il Lee, Yong Sup Choi, Hyun Jae Park
The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10(-3) Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040974/a-retarding-potential-analyzer-design-for-kev-level-ion-thruster-beams
#12
Zhe Zhang, Haibin Tang, Zun Zhang, Joseph Wang, Shuai Cao
We present a new Retarding Potential Analyzer (RPA) design that is capable of measuring keV-level energy, high-density plasma beams. This instrument overcomes the limitations of existing RPAs and can operate in plasmas with densities in excess of 1 × 10(15) m(-3) and ion energies up to 1200 eV. The RPA design parameters were determined by analyzing the electron density and temperature, the sheath thickness, and the ion density in the beam based on the Faraday probe and Langmuir probe measurements. A previously unobserved grid spacing arcing phenomenon was observed in experiments...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040973/combined-laser-ultrasonics-laser-heating-and-raman-scattering-in-diamond-anvil-cell-system
#13
Pavel V Zinin, Vitali B Prakapenka, Katherine Burgess, Shoko Odake, Nikolay Chigarev, Shiv K Sharma
We developed a multi-functional in situ measurement system under high pressure equipped with a laser ultrasonics (LU) system, Raman device, and laser heating system (LU-LH) in a diamond anvil cell (DAC). The system consists of four components: (1) a LU-DAC system (probe and pump lasers, photodetector, and oscilloscope) and DAC; (2) a fiber laser, which is designed to allow precise control of the total power in the range from 2 to 100 W by changing the diode current, for heating samples; (3) a spectrometer for measuring the temperature of the sample (using black body radiation), fluorescence spectrum (spectrum of the ruby for pressure measurement), and Raman scattering measurements inside a DAC under high pressure and high temperature (HPHT) conditions; and (4) an optical system to focus laser beams on the sample and image it in the DAC...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040972/research-on-ultra-fast-vacuum-mechanical-switch-driven-by-repulsive-force-actuator
#14
Zhao Yuan, Junjia He, Yuan Pan, Xin Jing, Canyi Zhong, Ning Zhang, Xiaoguang Wei, Guangfu Tang
In order to meet the fast operation demands of DC circuit breakers, a high-speed vacuum mechanical switch (VMS) driven by a repulsive force actuator is focused. To improve the drive speed and energy conversion efficiency (ECE) of the actuators, the dynamic characteristics of the double sided coil repulsive force actuators are investigated, and two generalized optimization design methods focusing on the aspect ratio of the driving coils (defined as ARF) and the electrical parameters (defined as EF) are developed...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040971/note-stability-control-of-intermediate-frequencies-of-a-three-laser-far-infrared-polarimeter-interferometer-system
#15
Jiang-Tao Yu, He-Ping Li, Qiu-Yue Nie, Zhi-Yong Zou, Hai-Qing Liu, Cheng-Yu Bao, Yin-Xian Jie, Zhan-Xian Li
Stability of the intermediate frequency (IF) in the far-infrared polarimeter-interferometer diagnostic system is critically important for the long pulse discharge experiments on the EAST tokamak. In this note, a real-time remote/local IF stability control system is described. The measured plasma parameters, including the Faraday rotation angle, electron density, lower hybrid wave, and plasma current, are obtained with the aid of this newly developed IF stability control system.
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040970/seeking-maximum-linearity-of-transfer-functions
#16
Filipi N Silva, Cesar H Comin, Luciano da F Costa
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 real system), 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 A transistor current amplifier...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040969/sequential-time-interleaved-random-equivalent-sampling-for-repetitive-signal
#17
Yijiu Zhao, Jingjing Liu
Compressed sensing (CS) based sampling techniques exhibit many advantages over other existing approaches for sparse signal spectrum sensing; they are also incorporated into non-uniform sampling signal reconstruction to improve the efficiency, such as random equivalent sampling (RES). However, in CS based RES, only one sample of each acquisition is considered in the signal reconstruction stage, and it will result in more acquisition runs and longer sampling time. In this paper, a sampling sequence is taken in each RES acquisition run, and the corresponding block measurement matrix is constructed using a Whittaker-Shannon interpolation formula...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040968/a-new-method-of-probing-mechanical-losses-of-coatings-at-cryogenic-temperatures
#18
Serge Galliou, Samuel Deléglise, Maxim Goryachev, Leonhard Neuhaus, Gianpietro Cagnoli, Salim Zerkani, Vincent Dolique, Jérémy Bon, Xavier Vacheret, Philippe Abbé, Laurent Pinard, Christophe Michel, Thibaut Karassouloff, Tristan Briant, Pierre-François Cohadon, Antoine Heidmann, Michael E Tobar, Roger Bourquin
A new method of probing mechanical losses and comparing the corresponding deposition processes of metallic and dielectric coatings in 1-100 MHz frequency range and cryogenic temperatures is presented. The method is based on the use of high-quality quartz acoustic cavities whose internal losses are orders of magnitude lower than any available coating nowadays. The approach is demonstrated for chromium, chromium/gold, and multilayer tantala/silica coatings. The Ta2O5/SiO2 coating has been found to exhibit a loss angle lower than 1...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040967/tunable-transportable-spectroradiometer-based-on-an-acousto-optical-tunable-filter-development-and-optical-performance
#19
O Kozlova, A Sadouni, D Truong, S Briaudeau, M Himbert
We describe a high-performance, transportable, versatile spectroradiometer based on an acousto-optical tunable filter (AOTF). The instrument was developed for temperature metrology, namely, to determine the thermodynamic temperature of black bodies above the Ag freezing point (961.78 °C). Its main design feature is the attenuation of the diffraction side lobes (and, thus, out-of-band stray light) thanks to the use of a double-pass configuration. The radiofrequency tuning of the AOTF allows continuous, fine, and rapid wavelength control over a wide spectral range (650 nm-1000 nm)...
December 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28040966/design-of-an-accurate-wireless-data-logger-for-vibration-analysis-with-android-interface
#20
J R Blanco, J Menéndez, F J Ferrero, J C Campo, M Valledor
In this work a new accurate wireless data logger using the Android interface 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...
December 2016: Review of Scientific Instruments
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