共查询到20条相似文献,搜索用时 328 毫秒
1.
The current — overpotential characteristics of the H2 - Pd - SCY interphase have been studied at atmospheric total pressure and temparatures between 400 – 550 °C in the single
chamber reactor — cell: Pd | SCY | Pd. The results of I−η measurements indicate that the apparent anodic and cathodic charge
tranfer coefficients are equal to: αa=αc=0.5. The present results are compared to those obtained with the single — chamber reactor cell: Ag | SCY | Ag. A solid state
proton (H+) conducting reactor — cell with Pd electrodes was tested for the ammonia synthesis from its elements at atmospheric pressure.
At 570 °C, over 75% of the ectrochemically supplied hydrogen was converted into NH3. The thermodynamic requirement for a high pressure process was eliminated.
Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998. 相似文献
2.
Abstract
Porous pressure-sensitive paint (PSP) is employed as a visualization technique for unsteady flow features on a low-pressure turbine blade. Recognizing that the measurement of high-frequency pressure fluctuations in unsteady flows—especially in turbomachinery—has proven to be difficult, recent advancements in the development of porous PSP have enabled the high-resolution measurement of pressure fields with frequency content of at least 20 kHz. In this work, PSP is applied to an L1A low-pressure turbine blade section (Re = 20,000 based on axial chord) to visualize the surface dynamics of a vortex generator jet (VGJ) pulsed at 10.6 Hz with nitrogen gas. Intensity-based, time-resolved PSP measurements reveal the development and the surface structure of the VGJ as well as the spanwise variation in the blowing profile. 相似文献3.
Mark A. Rubin 《Foundations of Physics》2006,36(8):1115-1159
Stapp claims that, when spatial degrees of freedom are taken into account, Everett quantum mechanics is ambiguous due to a “core basis problem.” To examine an aspect of this claim I generalize the ideal measurement model to include translational degrees of freedom for both the measured system and the measuring apparatus. Analysis of this generalized model using the Everett interpretation in the Heisenberg picture shows that it makes unambiguous predictions for the possible results of measurements and their respective probabilities. The presence of translational degrees of freedom for the measuring apparatus affects the probabilities of measurement outcomes in the same way that a mixed state for the measured system would. Examination of a measurement scenario involving several observers illustrates the consistency of the model with perceived spatial localization of the measuring apparatus.This work was sponsored by the Air Force under Air Force Contract FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the U.S. Government. 相似文献
4.
V. M. Shmelev A. D. Margolin N. Ya. Vasilik V. G. Krupkin V. T. Volov D. B. Volov 《Technical Physics》1998,43(9):1069-1071
An alternative, nonelectrical method for obtaining a dense radiating plasma and the possibilities of using this method to
pump solid-state lasers are investigated. The plasma was obtained experimentally by heating the working gas in a two-stage
ballistic plasmatron. A new device — a vortex chamber — is proposed for transferring energy into the plasmatron-laser system.
Zh. Tekh. Fiz. 68, 67–70 (September 1998) 相似文献
5.
L. S. Schulman 《Foundations of Physics》1997,27(12):1623-1636
The quantum Zeno effect (QZE) is often associated with the ironic maxim, “a watched pot never boils”, although the notion
of “watching” suggests a continuous activity at odds with the usual (pulsed measurement) presentation of the QZE. We show
how continuous watching can provide the same halting of decay as the usual QZE, and, for incomplete hindrance, we provide
a precise connection between the interval between projections and the response time of the continuous observer. Thus, watching
closely, but not so closely as to halt the “boiling”, is equivalent to—gives the same degree of partial hindrance as—pulsed
measurements with a particular pulsing rate. Our demonstration is accomplished by treating the apparatus for the continuous
watching as a fully quantum object. This in turn allows us a second perspective on the QZE, in which it is the modified level
structure of the combined system/apparatus Hamiltonian that slows the decay. This and other considerations favor the characterization
“dominated time evolution” for the QZE. 相似文献
6.
An automated setup for impedance measurements of NOX sensors and sensor elements has been assembled. The NOX atmosphere is generated using NO and NO2 calibration mixtures and N2. The mixture is passed to the measurement chamber, where impedance measurements are performed. The sample can be subjected
to temperature between 50 and 800 °C. The gas mixture is passed to the chemiluminescence analyser, where NOX and NO amount is determined. The automation is based on National Instruments LabView programming language. Gas flow control,
impedance measurement and NOX level analysis can be simultaneously performed using a single PC computer.
Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 – 18, 2004. 相似文献
7.
Jochen Rau 《Foundations of Physics》2011,41(3):380-388
I show that quantum theory is the only probabilistic framework that permits arbitrary processes to be emulated by sequences
of local measurements. This supports the view that, contrary to conventional wisdom, measurement should not be regarded as
a complex phenomenon in need of a dynamical explanation but rather as a primitive—and perhaps the only primitive—operation
of the theory. 相似文献
8.
G. Cirri M. Bianconi F. Cordero A. Bicci M. Dobrowolny C. Bonifazi 《Il Nuovo Cimento C》1992,15(2):203-217
Summary This paper presents experimental results on the effects of increasing gas pressure on electron gun operations. The electron
gun used is the gun EGA which has been developed for the TSS-1 mission. Various gases have been used with pressures in the
range from 10−6 to a few times 10−3 mbar. The measurements, taken in a vacuum chamber, show a steady increase in the slope of theI–V characteristics of the gun when the pressure is increased, as a consequence of ionization phenomena induced by the electron
beam. Further measurements have been taken of the overall current on a target at some distance from the gun itself. An attempt
is also made at a theoretical calculation of the effects observed, based on simplified models. 相似文献
9.
Electron cyclotron resonance (ECR) plasma breakdown is studied in a small linear cylindrical system with four different gases
— hydrogen, helium, argon and nitrogen. Microwave power in the experimental system is delivered by a magnetron at 2.45 ± 0.02
GHz in TE10 mode and launched radially to have extra-ordinary (X) wave in plasma. The axial magnetic field required for ECR in the system
is such that the fundamental ECR surface (B = 875.0 G) resides at the geometrical centre of the plasma system. ECR breakdown parameters such as plasma delay time and
plasma decay time from plasma density measurements are carried out at the centre using a Langmuir probe. The operating parameters
such as working gas pressure (1 × 10−5−1× 10−2 mbar) and input microwave power (160–800 W) are varied and the corresponding effect on the breakdown parameters is studied.
The experimental results obtained are presented in this paper.
相似文献
10.
11.
N. D. Lowhorn W. Wong-Ng W. Zhang Z. Q. Lu M. Otani E. Thomas M. Green T. N. Tran N. Dilley S. Ghamaty N. Elsner T. Hogan A. D. Downey Q. Jie Q. Li H. Obara J. Sharp C. Caylor R. Venkatasubramanian R. Willigan J. Yang J. Martin G. Nolas B. Edwards T. Tritt 《Applied Physics A: Materials Science & Processing》2009,94(2):231-234
A Standard Reference Material (SRM™) for the Seebeck coefficient is critical for inter-laboratory data comparison and for instrument calibration. To develop
this SRM™, we have conducted an international round-robin measurement survey of two candidate materials—undoped Bi2Te3 and constantan (55% Cu and 45% Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active
thermoelectric research using a number of commercial and custom-built measurement systems and techniques. We report the results
of these measurements and the statistical analysis performed. Based on this extensive study, we have selected Bi2Te3 as the prototype standard material. 相似文献
12.
E. M. Maev V. A. Andreev T. A. Case K. M. Crowe P. U. Dick A. Dijksman J. Egger D. Fahrni A. A. Fetisov V. A. Ganzha F. J. Hartmann P. Kammel A. G. Krivchitch O. E. Maev C. Petitjean G. E. Petrov R. Prieels S. M. Sadetsky G. N. Schapkin R. Schmidt G. G. Semenchuk M. Soroka A. A. Vorobyov N. I. Voropaev 《Hyperfine Interactions》2001,138(1-4):451-457
A new experiment is under preparation with the aim to improve considerably the present knowledge of the rate Λ
s
, which should be measured on a level of 1% or better, for the basic electroweak capture reaction of a negative muon on the
free proton μp
1s
→ n + νμ. The capture rate will be determined by measuring the lifetime of μ− stopped in ultra pure hydrogen at 10 bar pressure and comparing it with the lifetime of the unbound μ+. A new experimental method was developed for this project which should allow measuring the μ− lifetime with at least 10 ppm precision. The basic element of the detector is operating in the hydrogen gas time projection
chamber (TPC) surrounded by multi-wire proportional chambers (MWPCs) and scintillator counters. The arrival times and trajectories
of the incoming muons and the outgoing decay electrons are measured with this device providing effective suppression of background.
Using the TPC as an active target, we can monitor on-line the protium contamination by impurities with a sensitivity better
than 10−8. This can be done by detecting the charged products of the muon capture reaction on these impurities. It was demonstrated
that the TPC and MWPCs can operate in pure hydrogen under 10 bar pressure providing gas gain up to 10 000.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
Pilar Ferrer Juan Rubio‐Zuazo Catherine Heyman Fatima Esteban‐Betegón Germán R. Castro 《Journal of synchrotron radiation》2013,20(3):474-481
The multipurpose portable ultra‐high‐vacuum‐compatible chamber described in detail in this article has been designed to carry out grazing‐incidence X‐ray scattering techniques on the BM25‐SpLine CRG beamline at the ESRF. The chamber has a cylindrical form, built on a 360° beryllium double‐ended conflate flange (CF) nipple. The main advantage of this chamber design is the wide sample temperature range, which may be varied between 60 and 1000 K. Other advantages of using a cylinder are that the wall thickness is reduced to a minimum value, keeping maximal solid angle accessibility and keeping wall absorption of the incoming X‐ray beam constant. The heat exchanger is a customized compact liquid‐nitrogen (LN2) continuous‐flow cryostat. LN2 is transferred from a storage Dewar through a vacuum‐isolated transfer line to the heat exchanger. The sample is mounted on a molybdenum support on the heat exchanger, which is equipped with a BORALECTRIC heater element. The chamber versatility extends to the operating pressure, ranging from ultra‐high vacuum (<10?10 mbar) to high pressure (up to 3 × 103 mbar). In addition, it is equipped with several CF ports to allocate auxiliary components such as capillary gas‐inlet, viewports, leak valves, ion gun, turbo pump, etc., responding to a large variety of experiment requirements. A movable slits set‐up has been foreseen to reduce the background and diffuse scattering produced at the beryllium wall. Diffraction data can be recorded either with a point detector or with a bi‐dimensional CCD detector, or both detectors simultaneously. The system has been designed to carry out a multitude of experiments in a large variety of environments. The system feasibility is demonstrated by showing temperature‐dependence grazing‐incidence X‐ray diffraction and conductivity measurements on a 20 nm‐thick La0.7Ca0.3MnO3 thin film grown on a SrTiO3(001) substrate. 相似文献
14.
J. Uotila 《The European physical journal. Special topics》2008,153(1):401-404
A new prototype of a portable differential photoacoustic
measurement system was designed and built. The system applies the gas filter
correlation method. A blackbody radiator is used as a radiation source,
which allows measurements of great variety of different IR absorbing gases.
The prototype exploits the high sensitivity of a cantilever pressure sensor.
The differential design allows a selective real time measurement for a
single gas in open air or from the flowing sample. For the first time the
photoacoustic cell geometry for an acceleration noise damping was integrated
to a differential detector. The system has potential applications anywhere
that sensitive in-situ-measurements are required: for example in process
control technology, air quality monitoring, exhale monitoring, alarm devices
and food industry. The measurement of nitric oxide was modeled in the
presence of water vapor. As an example the concentration of water vapor,
that is acceptable if ppb-level nitric oxide measurements are to be done,
was calculated. With a typical band pass filter and a blackbody radiator the
amount is 20 ppm with 1.3 s integration time. The concentration was also
calculated to diode laser operating at 2.663 μm and quantum cascade
laser at 5.263 μm. The respective concentrations were 2 ppm and 6600 ppm. 相似文献
15.
D. Hertler R. Stirn S. Arndt R. Grzeszik A. Dreizler 《Applied physics. B, Lasers and optics》2011,104(2):399-407
This study presents the results of laser-induced incandescence (LII) measurements in an optically accessible gasoline direct
injection engine. The focus was to evaluate LII as a particle measurement technique which is able to provide a deeper understanding
of the underlying reaction and formation processes of soot in order to optimize the injection system to reduce exhaust gas
emissions. A comparison of time-resolved LII, based on the model described by Michelsen, with an Engine Exhaust Particle Sizer
(EEPS) was performed. In this context, the air–fuel ratio, the injection pressure and the injection timing have been varied
while applying the measurement techniques in the exhaust system. In case of a variation of the air–fuel ratio, two-dimensional
LII has been performed in the combustion chamber additionally. For each measurement, the Filter Smoke Number (FSN) was taken
into account as well. Finally, a good agreement of the different techniques was achieved. Moreover, we found that by combining
time-resolved LII and EEPS a differentiation of primary particles and agglomerates is possible. Consequently, a determination
of the processes in the combustion chamber and agglomeration in the exhaust gas is feasible. 相似文献
16.
The mass spectra of the residual gas in a metallic vacuum chamber of capacity 3 l are studied with an MI-9303 high-resolution
magnetic resonance mass spectrometer in the mass range 1–140 u. The experiments are carried out under four evacuation conditions
in the pressure range P = 10−8–10−10 Torr, and almost all the mass peaks forming multiplets are resolved. It is shown that the multiplets with mass numbers M≤80 have, as a rule, a multicomponent structure and hydrogen is the basic component responsible for the total pressure in
the chamber irrespective of evacuation conditions. Next in order of intensity in the mass spectra are, CH
4
+
, H2O+, CO+, and CO
2
+
peaks. Other lines in the residual gas spectra are largely due to various C-, H-, N-, and O-based compounds. In addition,
the background mass spectrum involves Cl-and F-based compounds and noble gas isotopes. The multiplets with M > 80 often degenerate into a single hydrocarbon line. 相似文献
17.
A method is described for measuring the light pressure and energy of a laser pulse. The method is based on a transformation of the kinetic energy acquired by a suspended object from the laser pulse into the potential energy of a twisted elastic filament. Comparative measurements are made of the energy radiated by a pulsed ruby laser ( = 6943 Å) by a calorimetric method and by a method based on measurement of the light pressure. This latter method essentially eliminates the influence of the radiometric effect on the measured results. It permits a quite accurate measurement of the light pressure and energy of a laser pulse at pressures of the order of 10–5 torr and below.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol.12, No. 6, pp. 48–54, June, 1969. 相似文献
18.
B. Grouiez V. Zeninari L. Joly B. Parvitte 《Applied physics. B, Lasers and optics》2010,100(2):265-273
Pulsed quantum-cascade-laser spectrometers are usually used to detect atmospheric gases with either the interpulse technique
(short pulses, typically 5–20 ns) or the intrapulse technique (long pulses, typically 500–800 ns). Each of these techniques
has its drawbacks. Particularly the gas absorption spectra are generally distorted. We have previously developed another technique
called intermediate-size pulses (typically 50–100 ns) technique for gas detection using pulsed QCL spectrometers. In this
paper, infrared spectra of ammonia recorded with this technique in the 10 μm region are presented. For the NH3 spectra recorded at low pressure (i.e. in the mbar range), the spectra show typical oscillations after the absorption. The
Beer–Lambert law cannot explain these oscillations, termed the rapid-passage effect. Comparisons between experimental and
calculated spectra will be realized. This phenomenon is not satisfactory from a spectroscopic point of view and spectra must
be recorded at higher pressures. For the NH3 spectra recorded at higher pressure (i.e. in the 50 mbar range), the oscillations disappear and the Beer–Lambert law could
be reused. This paper will demonstrate that the intermediate-size technique gives reliable measurements for NH3 detection. Moreover the typical apparatus function (0.003 cm−1 HWHM) is far lower from the typical apparatus function of the interpulse QCL spectrometers (0.015 cm−1 HWHM). 相似文献
19.
E.M. Maev D.V. Balin T. Case K.M. Crowe A. Del Rosso V.A. Ganzha F.J. Hartmann S.M. Kozlov B. Lauss O.E. Maev M. Mühlbauer F. Mulhauser C. Petitjean G.E. Petrov S.M. Sadetsky G.N. Schapkin W. Schott G.G. Semenchuk Yu.V. Smirenin M.A. Soroka A.A. Vasiliev A.A. Vorobyov N.I. Voropaev J. Zmeskal 《Hyperfine Interactions》1999,118(1-4):171-176
We report on the results of an experiment aimed at observing muon-catalyzed d
3He-fusion with a setup previously used for studies of the muon-catalyzed dd-fusion. The basic element of the setup is a high
pressure ionization chamber operating as an active target. In this experiment the chamber was filled with an HD + 3He (5.6%) gas mixture at 13.2 bar pressure and 50 K temperature. These conditions were chosen as optimal for formation of
the 3Heμd-molecules with a low level of background from the d-μ-d fusion. The chamber was exposed to the negative muon beam at PSI. During a 3-week data-taking period, 9.7 × 108 muon stops have been selected. The analysis of the data was able to determine a new upper limit for the d
3He-fusion rate in the 3Heμd-molecule (λf≤ 6× 104 s-1), which is more than three orders of magnitude lower than the previously existed limit.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
A portable modular gas sensor for measuring the 13C/12C isotopic ratio in CO2 with a precision of 0.8‰(±1σ) was developed for volcanic gas emission studies. This sensor employed a difference frequency generation (DFG)-based spectroscopic
source operating at 4.35 μm (∼2300 cm-1) in combination with a dual-chamber gas absorption cell. Direct absorption spectroscopy using this specially designed cell
permitted rapid comparisons of isotopic ratios of a gas sample and a reference standard for appropriately selected CO2 absorption lines. Special attention was given to minimizing undesirable precision degrading effects, in particular temperature
and pressure fluctuations.
Received: 16 April 2002 / Revised version: 28 May 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-713/5245237, E-mail: fkt@rice.edu 相似文献