Experimental Setup For Simultaneous Measurement Research Articles

Simultaneous Magnetic Shielding and Magnetization Loss Measurements of YBCO Cylinders at Variable Temperatures Under Cryogenic Helium Gas Circulation

A novel experimental setup for simultaneous measurements of magnetic shielding characteristics and magnetization ac loss measurements is described. The measurement system consists of a controllable helium circulation system that enables cooling of the samples to temperatures as low as 15 K and simultaneously allows calorimetric ac loss measurements. The simultaneous measurement of shielding characteristics and ac losses permits estimation of losses in realistic operating conditions of high-temperature superconducting magnetic shields. It is shown that if the extent of losses is high compared with the cooling efficiency, the magnetic shields could quench. The data on magnetic shielding efficacy along with the corresponding magnetization losses are presented.

Quadrant analysis of turbulent pollution flux above the modelled street intersection

The objective of this experimental study is to determine processes of a vertical turbulent pollution transport above the X-shaped street intersection in an idealised symmetric urban area for several approach flow directions. An experimental set-up for simultaneous measurement of the flow velocity and the tracer gas concentration in a high temporal resolution is assembled. Vertical turbulent scalar fluxes are computed from the measured data in a horizontal plane above the street intersection. The quadrant analysis was applied to the vertical turbulent pollution fluxes data. Events with dominant contribution to vertical turbulent pollution flux were detected. The mean duration, repetition frequency and the duration percentage were computed for these events. A strong influence of the approach flow direction on the the type of dominant events and their characteristics was resolved.

In Situ Monitoring of Stirring Effects on Polymorphic Transformations during Cooling Crystallization of Carbamazepine

The influence of experimental conditions on polymorphic outcome and transformations during cooling crystallization of carbamazepine (CBZ) from anhydrous ethanol has been investigated. Stirring was found to be the most important controlling factor for the initial polymorphic outcome in solutions prepared using commercial CBZ powder. For quiescent conditions, a few large crystals of the metastable trigonal α form (II) initially appeared, undergoing subsequent slow transformation into the stable P-monoclinic β form (III). Under sufficiently vigorous stirring, the induction times observed were clearly defined by the onset of turbidity, which was due to formation of a large number of small form III prismatic crystals. In experiments with solutions prepared by using recrystallized CBZ, significantly shorter induction times were observed under stirring conditions: a large number of small form II needle-shaped crystals initially formed at the onset of turbidity and then relatively rapidly transformed to small crystals of form III. This indicates a possible effect of impurities in the commercial CBZ powder inhibiting rapid nucleation of form II under stirring conditions. In situ monitoring of CBZ polymorphic outcome was performed using custom-built experimental setup for simultaneous measurement of intensity of transmitted and scattered light. Distinct pathways in two-variable intensity plots were observed for formation of each respective polymorph under stirring conditions. The same monitoring technique should be readily applicable to other systems.

Laser opto-acoustic study of phase transitions in metals confined by transparent dielectric

First-order phase transitions in metal induced by nanosecond laser pulse are studied here. The metal surface is irradiated through a layer of transparent dielectric—an optical glass. Such confinement considerably increases the efficiency of pressure generation at the metal surface. This technique allows to obtain near-critical states of metals—with temperatures ∼104 K and pressures ∼104 atm with table-top equipment. At the same time the glass prevents the ablation plume formation—so the surface temperature can be measured using thermal radiation data. An experimental setup for simultaneous measurements of pressure, temperature and reflectivity was assembled based on the elaborated method of experimental research. The processes of melting of lead and boiling of mercury were studied. The onset of the phase transition process led to a considerable tightening of the pressure pulse. A substantial drop of surface reflectivity due to increase of temperature and decrease of density was observed.

Laser optoacoustic study of near‐critical states and phase transitions in metals

Pulsed laser optoacoustic technique is used for generation and study of near‐critical states and phase transitions in metals. Metal surface is confined by a layer of transparent dielectric. In this case the efficiency of pressure generation is much greater than in case of the free surface so it is possible to achieve states of metals with relatively high thermodynamic parameters: P ∼104 atm and T ̃ 104 K with a table‐top laser system. The experimental setup for simultaneous measurements of pressure, temperature, and reflectivity of metal surface with nanosecond temporal resolution was assembled. Q‐switched Nd:YAG laser with pulse duration ̃ ∼10 ns and pulse energy ∼1 J was used. Pressure was measured using LiNbO3 piezotransducer. Temperature was obtained with optical pyrometer. Lead and mercury were chosen as test metals. Pressure pulses up to 1 kbar in lead and up to 7 kbar in mercury (with T ∼2400 K ‐ super‐critical area of the phase diagram for Hg) were obtained. The curve of laser heating process in P‐T coordinates was plotted. The measurements of optical properties showed considerable decrease of surface reflectivity both for lead and mercury at high laser fluences due to increase of temperature and density decrease.

Friction of elastomer-on-glass system and direct observation of its frictional interface

We performed a study on the static friction of PDMS elastomers with well-defined surface topography sliding over glass. An experimental setup for simultaneous measurements of friction force and direct observations of frictional interface has been developed. The static friction force was nearly proportional to normal load. The static friction force was independent of stick time. The simultaneous measurements revealed that the static friction force was proportional to the total area of contact. The coefficient was nearly independent of the surface topography of PDMS elastomers.

Simultaneous measurement of patterns in the signal and idler near and far fields from a confocal optical parametrical oscillator with applications in quantum optics

We present the results of an experimental investigation of multimode intensity patterns from an optical parametric oscillator operating above threshold and show that it oscillates in 10-15 transverse modes strongly coupled through the nonlinear crystal, which makes this setup useful for future investigation of quantum correlations in the transverse plane. We describe the experimental setup for simultaneous measurements of signal and idler near- and far-field patterns and analyze the effects of various experimental complications such as walk-off and thermal index changes on the generated patterns. We also show that the oscillator can be stabilized by optical feedback, indicating a possible route for controlling the generated intensity patterns.

Simultaneous measurement of electrical and thermal properties: Application to margarine

An experimental set-up for simultaneous measurement of thermal and dielectric properties of pasty materials, and in particular of margarine is proposed. The objective of the study was to observe simultaneously how the above mentioned properties change when margarine undergoes temperature changes within a temperature range that also encompasses its melting point. The PVDF pyroelectric sensor in combination with the plane plate capacitor was used for simultaneous measurement avoiding thereby problems arising from differences in both, sample's quantity and specific portion taken, the illumination level, heating, etc. As result of temperature variations both, the electrical and thermal properties of margarine were shown very sensitive to the structural changes. The reversibility of the modification process was observed. The results obtained with the set-up for simultaneous measurements were compared to those acquired by the methods capable of measuring each of the two properties separately.

Experimental setup for simultaneous measurements of neutron diffraction and dielectric spectroscopy during crystallization of liquids

Here we present an experimental setup to obtain information on structural and dynamical changes in liquids during crystallization. This setup consists in a sample cell that allows performing simultaneous measurements of neutron diffraction and dielectric spectroscopy experiments. The capabilities of the technique have been probed by following in real time the crystallization process of a model liquid: the isopropanol. By performing the simultaneous experiment information can be obtained from both phases, amorphous and crystalline, and therefore it can provide a complete description of the changes occurring during a crystallization process. The use of this setup allowed us to demonstrate that a breakage of the hydrogen-bond network is a precursor step for the crystallization of isopropanol.

A magnetic resonance-compatible experimental set-up for hyperthermia studies.

This study presents the development and testing of an experimental set-up for simultaneous measurements of pH (intracellular by MR and extracellular by fibre-optic pH meter), tumour bio-energetics (by MR), and core/tumour temperatures (by thermocouples) in tumour-bearing mice. Potential sources of measurement errors when using these techniques concurrently in an MR set-up are discussed. Emphasis is placed on simple practical solutions to these problems.

A quasi two-dimensional bubble method for surface tension and contact angle measurements at the crystal-melt interface. II. Physical realization

An experimental setup for simultaneous measurement of the surface tension of a liquid and of the contact angle at the solid-liquid interface between a crystal and its own melt, is described. The method is based on shape determination of a gas bubble captured at the crystal-melt interface inside a thin cell composed of two plane-parallel glass plates, in contact with a temperature gradient heating block. The feasibility of the method is demonstrated in the case of coumarin.

Thermal conductivity of YBCO and thermal conductance at YBCO/ruby boundary Part 1: Joint experimental set-up for simultaneous measurements and experimental study in the temperature range 10–260 K

A joint experimental set-up has been constructed for simultaneous low temperature measurements of thermal conductivity, k, of two solid samples and thermal conductance, R b −1, at a solid/solid boundary using the steady state method. The thermal measurements presented here were carried out in the temperature range 10–260 K. A discussion of the peculiarities of the thermal conductivity behaviour of YBCO superconducting samples during the cooling cycle has been presented. Initial thermal boundary conductance measurements at the high temperature superconductor/solid (YBCO/ruby) boundary have been performed.

A method of determining photonucleon cross sections for separate residual nuclei states utilizing continuum gamma-ray sources

An experimental set-up for simultaneous measurement of photoprotons and deexcitation gamma rays in the giant resonance energy region is used for evaluation of photoparticle cross sections leading to different levels of residual nuclei. The system consists of a scattering chamber with four silicon surface-barrier detectors, allowing measurement of photoproton spectra at 8 angles between 30° and 150°, inclusive, and a Ge(Li) coaxial detector assembly for analysing gamma rays from excited residual nuclei states. A least-squares method is adopted for the calculation of (γ, p) cross sections. Two types of data are used in the calculation: photoproton spectra of different bremsstrahlung end- point energies, and the deexcitation gamma-ray spectra. The latter enable selection of those states in residual nuclei which are strongly populated in the reaction, and consequently reduce the number of free parameters in the least-squares analysis. Typical cross sections are presented to illustrate the effectiveness of the method.