Measurement of Temperature by Mach-Zehnder Interferometry

Subject of study. The shift direction of interference fringes depending on the sign of the local phase shift introduced to one of the interfering waves was investigated in terms of two-beam interferometry. Aim of study. This study aimed to validate the fact that two-beam interferometry based on a single interferogram enables definitive determination of the phase-shift sign using the shift direction of the interference fringe. Method. Positions of the interference fringes and their shifts were calculated considering the phase distribution of interfering waves in the observation plane. The Mach–Zehnder interferometer was used to experimentally confirm the obtained theoretical results. Two closely adjacent substrates were used as objects. A subwavelength layer of a standard material was deposited on a part of the surface of one substrate, and a layer of metamaterial was deposited on the part of the second substrate. Main results. Expressions determining the direction and amplitude of the shift of interference fringes depending on the sign and amplitude of the local phase shift in one of the two interfering waves with a plane or spherical front were obtained. Strict rules of interference fringe shift depending on the sign of the phase shift were formulated based on the calculations. Results of the experiment using the Mach–Zehnder interferometer with different combinations of beams with spherical and plane wavefronts confirmed the theoretical calculations. Practical significance. Classic interferometric methods require significant time and the application of complex experimental procedures to determine the sign of the phase shift. The application of the results obtained in this study enables the determination of the sign of the introduced local phase shift based on a single interferogram without additional time expenditures. Thus, the method investigating the metamaterial layers of a subwavelength thickness is significantly simplified.

Development of Transient Pulse Detonation Engine Cycle Analysis and Performance Prediction (PDE-CAPP) Code

This article presents dc magnetic flux bias suppression methods for a dual active bridge (DAB) converter in both steady state and transient process. The steady-state dc offset is caused by asymmetries of the circuit and power switches in practice, while the transient offset is caused by the sudden update of phase shift ratio. This dc bias will increase the conduction losses, lead to loss of zero voltage switching (ZVS), and even saturate the magnetic components. To prevent this risk, this article proposes methods to suppress the dc bias both in steady state and transient process. For steady-state dc bias suppression, the duty cycles of square voltages generated by the primary and secondary side H-bridges are regulated according to the dc bias current. The conditions to achieve zero dc bias and the small-signal model to regulate the dc bias current are derived. For transient dc bias suppression, the phase shift ratio variation is limited to ensure the peak inductor current within the safe operating range. Tunnel magnetoresistance (TMR) is employed to sense the currents, and an analog integration and sampling method is proposed to detect dc bias. Finally, the proposed method is verified through experimental results on a 3200-W DAB prototype.

Ammonia storage and slip under steady and transient state in close-coupled SCR

Optical device based on Mach Zehnder Interferometer (MZI) is usually used as the optical switching, modulator and many applications in telecommunication networks. This paper discuss the Temperature Effect of Wavelength Division Multiplexing (WDM) Interleaver by using single and cascaded MZI. The Sellmeier equation is used to calculate the refractive index changing caused by the temperature changing. The output power of MZI is obtained by using matrix equation. The characteristic of output power varied with several temperatures between 28 and 300 degree Celsius. The wavelength used in this simulation is in L-Band region which is about 1570–1610nm. Temperature changing cause the changing of refractive index of material. The temperature changing leads to the shifting of wavelength channel which describe the characteristic of thermo optic effect on single and cascaded MZI.

The conventional two-beam interferometry adopts only one expression about plasma density and thickness because only fringe shift is recognized from the recorded fringes. Therefore, the prior hypotheses that the plasma is thickness-uniform or circular symmetry have to be introduced to separate them, which limits the applied range and accuracy of the conventional method. This paper found that the laser beam will be deflected if the thickness changes, leading the recorded fringes to be defocused. As a result, a new expression relying on recognizing the defocus parameter of the recorded fringes is derived, and a pointwise separation algorithm to separate density and thickness is proposed based on the two expressions. Compared to the conventional algorithms, the new algorithm requires no hypotheses and thus has a wider applied range.

It is very important to understand the surface and volume charge transportation properties of high insulating materials, such as polyimide, in order to find suitable method to mitigate the electrostatic discharge (ESD) of certain sensitive components on spacecraft. An isothermal surface potential decay (ISPD) experiment is performed inside a ground based vacuum chamber on polyimide under a simulated space environment. Immediately after low energy electron beam irradiation on polyimide, the 2D surface potential distributions are measured by a non-contact potential probe under five various temperatures from 298 to 338 K. The surface potential decay of the insulating material can be divided into two categories: transient process and steady state process. The steady state process is determined by the surface and volume charge transportation properties of dielectric. An ISPD model with genetic algorithm (GA) is developed to reveal the steady state surface potential decay experimental results. From the GA analysis, we obtain the surface resistivity, volume Ohmic resistivity, and charge carrier mobility of polyimide at various temperatures. After analyzing the surface and volume charge transportation properties of the material as a function of temperature, we find that the surface resistivity, volume Ohmic resistivity, and charge carrier mobility are well fitted with the Arrhenius law. Consequently, surface activation energy, volume activation energy, and <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">trap energy</sub> of polyimide are found as 0.30 eV, 0.32 eV, and 0.54 eV, respectively.

Mechanical properties of G550 cold-formed steel under transient and steady state conditions

Experimental investigation of a model bulb turbine under steady state and load rejection process

Industrial buildings, as in the nuclear industry, are equipped with ventilation systems, the main role of which is to ensure pollutant containment inside the facility during normal, damaged or accidental situations. To do this, the ventilation system is designed to maintain rooms at lower pressure with respect to the outside environment. The air, taken from the outside, thus flows from the rooms with the lowest contamination risk to the rooms with the highest contamination risk, before being filtered and released into the atmosphere. Wind creates pressure fields along the external envelope and communicating openings of the facility, which can modify internal airflows, notably leakage flow rates of rooms. In order to study the combined effects of wind and mechanical ventilation, a methodology for carrying out reduced-scale experiments to predict isothermal flows, in steady and transient states, has been developed and then numerically and experimentally validated. The application of this methodology to two standard nuclear configurations has led to experiments performed in the Jules Verne climatic wind tunnel of the CSTB in order to study the containment of this kind of configuration subjected to wind effects. It was shown that wind effects, in steady state, can lead to partial or total loss of the pollutant containment, with the mechanical ventilation on or off. Moreover, wind turbulence generates significant fluctuations of pressures and flow rates that can bring about instantaneous reversal leakage flow rates, which cannot be identified in steady state. From these experimental results, the zonal code SYLVIA, developed by IRSN and used notably to support safety assessments in nuclear buildings, has been validated for taking into account wind effects in steady and transient states.

Transient state analysis of separated flow around a sphere

In this series of articles, an attempt is made to find and to discover a mathematical method for analysis of the electromagnetic processes in ac-dc and/or dc-ac converters. This method based on the application of difference equations, makes it possible to describe the behaviour of converters in steady-state and transient processes. Analysis is applied to full-wave and half-wave power converters regardless of their specific schemes. The project will include 3 articles in this series: 1) General equations of ac-dc power converters for steady-state and transient processes, 2) Transient processes of ac-dc power converters, 3) Steady-state processes of ac-dc power converters. This series is a result of the author's investigations, begun at the Academy of Sciences of the USSR in 1969 and finished at the Ben-Gurion University of the Negev in 1975. The first stage of investigation was based on [1, 2]. Some first results were published [3, 4].

In the LPCVD reactor the temperature variations within the wafer load are the most important factor to maintain the thickness of the materials deposited on the surface of the wafer constant and to affect the deformation of each wafer. In this study the temporal variations of radial and axial temperature nonuniformities of each wafer in the LPCVD reactor are numerically estimated by assuming diffuse reflection. To verify the validity of the present numerical results, the present results obtained from the transient analysis are compared with those of Badgwell's work in which a steady-state condition was assumed. The main objective of this work is to determine the temporal variations of the temperature of each wafer in the LPCVD process since the wafers experience severe change in temperature in the early stage of the process.

Local deformation of a polymer mixture crosslinked by irradiation with ultraviolet light was in situ monitored by using a Mach‐Zehnder interferometer. In combination with the refractive index data obtained from independent measurements, the deformation in the nanometer scales of the crosslinked blends was calculated by using the difference in optical path length of the blend measured before and after irradiation. Upon varying the crosslink density of the blend by changing the light intensity, it was found that the local deformation well correlates with the crosslink density obtained from the reaction kinetics experiments. Furthermore, the strain relaxation of the blends was also monitored in situ and analyzed after irradiation over different time intervals. The results obtained in this study reveal the possibility of monitoring the nanometer‐scale deformation in polymers during radiation curing. These data also provide important information on the correlations between the irradiation‐induced elastic strain and the resulting morphology of reacting polymer blends. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2898–2913, 2005

It has been shown recently that non-Abelian states and the spin-polarized and unpolarized versions of the Abelian 331 state may have identical signatures in Fabry-P\'erot interferometry in the quantum Hall effect at filling factor 5/2. We calculate the Fano factor for the shot noise in a Mach-Zehnder interferometer in the 331 states and demonstrate that it differs from the Fano factor in the proposed non-Abelian states. The Fano factor depends periodically on the magnetic flux through the interferometer. Its maximal value is $2\ifmmode\times\else\texttimes\fi{}1.4e$ for the 331 states with a symmetry between two flavors of quasiparticles. In the absence of such symmetry the Fano factor can reach $2\ifmmode\times\else\texttimes\fi{}2.3e$. On the other hand, for the Pfaffian and anti-Pfaffian states the maximal Fano factor is $2\ifmmode\times\else\texttimes\fi{}3.2e$. The period of the flux dependence of the Fano factor is one flux quantum. If only quasiparticles of one flavor can tunnel through the interferometer then the period drops to one half of the flux quantum. We also discuss transport signatures of a general Halperin state with the filling factor $2+k/(k+2)$.