Miracle-dz/UniFAR-FTUs huggingface dataset:
Selection criteria for microphones used in pulsed nonresonant gas-phase photoacoustics

Theoretical and experimental investigations aimed at optimizing the detection performance in nonresonant pulsed photoacoustic (PA) studies in the gas phase by selecting microphones with appropriate characteristics are presented. An analytical function is introduced that allows the simulation of the measured signal-to-noise-ratio (SNR) for given microphone specifications. The crucial parameters for maximum SNR are the microphone responsivity, its bandwidth, and noise characteristics. Good agreement between calculated and measured PA signal shapes and their fast Fourier transform spectra is obtained. Comparisons of experimental data recorded in a gas mixture of 100 ppm ethylene buffered in synthetic air with various condenser and electret microphones with different characteristics confirm our theoretical predictions. The peak amplitude of the recorded microphone signal increases with decreasing laser beam radius rb. However, for standard microphones with a bandwidth of ≈20 kHz, there is no reason to use rb<.
All-silicon Fabry-Perot modulator based on the thermo-optic effect.

The operation at 1.5 μm of a silicon Fabry–Perot optical modulator is reported. The electrically driven device, which uses the thermo-optic effect to achieve as much as a 55% intensity modulation depth, has been realized by means of standard silicon microelectronic technology. This demonstrates that this new type of optical modulator can easily be integrated with electronic circuits. An accurate three-dimensional thermal analysis of the device has permitted the setup of a reliable numerical code aimed at the design of optimized integrated versions of it. The simulation outputs therefore predict operation frequencies of hundreds of kilohertz, remarkably superior to those previously reported in thermo-optic-effect-based modulators
Spacetime structures in simple quantum systems

Recently W Kinzel [1995 Phys. Bl. 51 1190] has argued that even simple quantum systems can exhibit surprising phenomena. As an example he presented the formation of canals and ridges in the time-dependent probability density of a particle caught in a square well with infinitely high walls. We show how these structures emerge from the wavefunction and present a simple derivation of their location in the spacetime continuum.
Effect of the electric arc and the ambient air on the contact resistance of silver, tungsten, and silver-tungsten contacts

Contact pairs of Ag, W, and Ag‐W were operated 6000 times in a 20‐A 110‐V ac circuit. The effect of contact‐resistance change was observed by measuring the temperature rise (TR) at the fixed contact while passing the steady‐state 20 A. The TR was measured before the switching had begun and after each 1000 operations. A large number of contact pairs were used in order to ensure a good statistical interpretation of the data. The chemical composition of the contact surfaces was measured using a Debye‐Scherer x‐ray analysis. The distribution of contact resistance for Ag contacts remained the same throughout the experiment. For W contacts, the distribution was initially higher than that for Ag: the result of conductivity and hardness differences. During the switching experiments, the formation of tungsten oxides on the contact surface resulted in high contact‐resistance values. For Ag‐W, the distribution was initially closer to that for Ag contacts: the result of a thin surface layer of Ag on the Ag‐W. During .
Some considerations on the instabilities of nonpolar liquids subjected to charge injection

The electrohydrodynamic stability of a plane layer of nonpolar liquid is analyzed under certain basic assumptions. The liquid is supposed to be perfectly insulating, the space charge resulting from a unipolar injection of charge. The injection is considered to be nonautonomous, that is, following a field dependent law. The regions of linear stability under stationary conditions have been computed both in terms of nondimensional parameters and directly measurable variables, such as the applied voltage and the gap spacing between the electrodes. The results have shown that the onset of instability is strongly dependent on an injection strength parameter and can be approximated by the linear criterion corresponding to autonomous injection, provided that the injected charge is given by the injection law. Experiments have also been performed to determine the instability threshold under transient conditions. An interpretation of these experiments has been done by generalizing an approximated theoretical study f.
Robust Two-Stage Approach Outperforms Robust Full Information Maximum Likelihood With Incomplete Nonnormal Data

This article builds on the work of Savalei and Bentler (2009), who proposed and evaluated a statistically justified two-stage (TS) approach for fitting structural equation models with incomplete normally distributed data. The TS approach first obtains saturated maximum likelihood (ML) estimates of the population means and covariance matrix and then uses these saturated estimates in the complete data ML fitting function. Standard errors and test statistics are then adjusted to reflect uncertainty due to missing data. This work presents an extension of the TS methodology to nonnormal incomplete data (robust TS) and conducts an empirical evaluation of its performance relative to the full information maximum likelihood (FIML) approach with robust standard errors and a scaled chi-square statistic. The results indicate that although TS parameter estimates are slightly lower in efficiency, the TS approach performs better than FIML in terms of coverage and the rejection rate of the scaled chi-square across a wide variety of conditions. Its wide implementation and further study are encouraged.
The scaling law in the hole erosion test with a constant pressure drop

A process called ‘piping’, which often occurs in the soil at dams, levees, and dykes, involves the formation and development of a continuous tunnel between upstream and downstream ends. The hole erosion test is commonly used to quantify the critical stress and the rate of piping erosion progression. The aim of this study is to draw up a model for interpreting the results of this test. A characteristic internal erosion time is defined and expressed as a function of the initial hydraulic gradient and the coefficient of surface erosion. It is established here that the product of the coefficient of erosion and the flow velocity is a significant dimensionless number: when this number is small, the kinetics of erosion are low, and the particle concentration does not have any effect on the flow. This finding applies to most of the available test results. Theoretical and experimental evidence is presented showing that the evolution of the pipe radius during erosion with a constant pressure drop obeys a scaling exponential law. Copyright © 2008 John Wiley & Sons, Ltd.
Notable internal thermal effect on the yielding of metallic glasses

We revealed a notable internal thermal effect on the yielding of metallic glasses with the aid of a newly developed microscopic model focusing on the interaction of incipient localized shear events. It is shown that at the high strain rate, localized heating in metallic glasses instead of localized structure change plays the dominant role in shear softening. Using the modified cooperative shear model with the ingredient of the thermal effect, we captured the sudden decrease of the strength of metallic glasses after a critical strain rate, which was found in experiments.
A family of Wiener transforms associated with a pair of operators on Hilbert space

In this article, for each pair of operators A and B on the complexification H of a given Hilbert space H′, we consider a family of Wiener transforms given by where f belongs to the class 𝒫 of complex-valued polynomials on H′ and the integration on H′ is performed with respect to the isonormal distribution g c of the variance parameter c>0. We characterize the composition formula, the inversion formula, the Parseval relation and the unitary extension of the Wiener transform to L 2 (H′, dg c ).
Reducing incentive constraints in bidimensional screening

This paper studies screening problems with quasilinear preferences, where agents' private information is two-dimensional and the allocation instrument is one-dimensional. We define a preorder to compare types based on their marginal valuation to the instrument, which facilitates the reduction of incentive compatibility constraints that must be checked. With this approach, the discretized problem becomes computationally tractable. As an application, we numerically solve a problem introduced by Lewis & Sappington (1988)
The physics of fracture in an unstable polymeric liquid

Entangled polymer solutions and melts show a variety of behaviours under different flow conditions. Recent step strain experiments [Macromolecules 42, 6261 (2009)] demonstrated a fracture-like behaviour that was interpreted in terms of a massive loss of entanglements after yielding. This was taken to violate the Doi-Edwards tube model [The Theory of Polymer Dynamics (Oxford University Press, New York, United States, 1986)]. Here this phenomenon is investigated using the Rolie-Poly model, which approximates a successful version of the DE theory. The results give close quantitative agreement with the experiments, as well as with the proposal by Marrucci and Grizzuti in 1983 that entangled polymer liquids possess an elastic instability. The `fracture' is a transient manifestation of this elastic instability that relies on the amplification of spatially inhomogeneous fluctuations. Linear stability analysis of the fluid shows that there is also a viscous contribution to this instability so that this fracture-like behaviour is possible before the elastic limit is reached.
A Reynolds-averaged turbulence modeling approach using three transport equations for the turbulent viscosity, kinetic energy, and dissipation rate

A Reynolds-averaged approach to turbulent shear flows is sought with resort to a three-equation method. Its novelty is the introduction of a turbulent-viscosity transport equation through the transport equation for the Reynolds stress in addition to those for the turbulent kinetic energy and the dissipation rate. The latter two equations are used for evaluating the dimensional coefficients in the former. The aim of this model is to enhance the capability to cope with nonstationary and advection effects in various turbulent flows. The adaptability to them is confirmed through the application to homogeneous-shear and supersonic free-shear flows. In particular, the reasonable prediction is obtained in the latter where the growth rate of the shear layer is suppressed with the increase in the convective Mach number. The present model is also applied to a three-dimensional flow past a wing tip as an instance of complex aeronautical flows, and the excessive diffusion of the trailing vortices is shown to be suppr.
Multiple scattering of light in inhomogeneous media and applications

Light scattering-based techniques are being developed for non-invasive diagnostics of inhomogeneous media in various fields, such as medicine, biology, and material characterization. However, as most media of interest are highly scattering and have a complex structure, it is difficult to obtain a full analytical solution of the scattering problem without introducing approximations and assumptions about the properties of the system under consideration. Moreover, most of the previous studies deal with idealized scattering situations, rarely encountered in practice. This dissertation provides new analytical, numerical, and experimental solutions to describe subtle effects introduced by the properties of the light sources, and by the boundaries, absorption and morphology of the investigated media. A novel Monte Carlo simulation was developed to describe the statistics of partially coherent beams after propagation through inhomogeneous media. The Monte Carlo approach also enabled us to study the influence of the refractive index contrast on the diffusive processes, to discern between different effects of absorption in multiple scattering, and to support experimental results on inhomogeneous media with complex morphology. A detailed description of chromatic effects in scattering was used to develop new models that explain the spectral dependence of the detected signal in applications such as imaging and diffuse reflectance measurements. The quantitative and non-invasive characterization of inhomogeneous media with complex structures, such as porous membranes, diffusive coatings, and incipient lesions in natural teeth was then demonstrated.
Oscillation for Third-Order Nonlinear Delay Dynamic Equations on Time Scales

The oscillation for certain third-order nonlinear neutral delay dynamic equations on time scales is discussed in this article. By using the generalized Riccati transformation and the inequality technique, three new different sufficient conditions which ensure that every solution is oscillatory or converges to zero are established. The results obtained essentially generalize and improve earlier ones.
BLUEs of Parameters of Generalized Geometric Distribution Using Ordered Ranked Set Sampling

ABSTRACT As an alternative to the best linear unbiased estimates based on order statistics (BLUE-OS) for general location-scale distributions given by Lloyd (1952) and Downton (1954), Bhoj and Ahsanullah (1996) presented the best linear unbiased estimates based on ranked set sample (BLUE-RSS) for the generalized geometric distribution. Hossain and Muttlak (2000) extended it to some other distributions, and gave the BLUE-RSS for the population mean and the standard deviation. Bhoj and Ahsanullah (1996) and Hossain and Muttlak (2000) arrived at the conclusion that the BLUE-RSS of the location parameter is more efficient than the BLUE-OS, while the BLUE-RSS of the scale parameter is not as efficient as the BLUE-OS for small n. In this article, we derive the best linear unbiased estimates using ordered ranked set sampling (BLUE-ORSS). These estimates are then compared with both BLUE-OS and BLUE-RSS for two special cases of the generalized geometric distribution. We show that BLUE-ORSS are uniformly better than BLUE-OS and BLUE-RSS not only for the location parameter but also for the scale parameter.
Changes in Forcecardiography Heartbeat Morphology Induced by Cardio-Respiratory Interactions

The cardiac function is influenced by respiration. In particular, various parameters such as cardiac time intervals and the stroke volume are modulated by respiratory activity. It has long been recognized that cardio-respiratory interactions modify the morphology of cardio-mechanical signals, e.g., phonocardiogram, seismocardiogram (SCG), and ballistocardiogram. Forcecardiography (FCG) records the weak forces induced on the chest wall by the mechanical activity of the heart and lungs and relies on specific force sensors that are capable of monitoring respiration, infrasonic cardiac vibrations, and heart sounds, all simultaneously from a single site on the chest. This study addressed the changes in FCG heartbeat morphology caused by respiration. Two respiratory-modulated parameters were considered, namely the left ventricular ejection time (LVET) and a morphological similarity index (MSi) between heartbeats. The time trends of these parameters were extracted from FCG signals and further analyzed to evaluate their consistency within the respiratory cycle in order to assess their relationship with the breathing activity. The respiratory acts were localized in the time trends of the LVET and MSi and compared with a reference respiratory signal by computing the sensitivity and positive predictive value (PPV). In addition, the agreement between the inter-breath intervals estimated from the LVET and MSi and those estimated from the reference respiratory signal was assessed via linear regression and Bland–Altman analyses. The results of this study clearly showed a tight relationship between the respiratory activity and the considered respiratory-modulated parameters. Both the LVET and MSi exhibited cyclic time trends that remarkably matched the reference respiratory signal. In addition, they achieved a very high sensitivity and PPV (LVET: 94.7% and 95.7%, respectively; MSi: 99.3% and 95.3%, respectively). The linear regression analysis reported almost unit slopes for both the LVET (R2 = 0.86) and MSi (R2 = 0.97); the Bland–Altman analysis reported a non-significant bias for both the LVET and MSi as well as limits of agreement of ±1.68 s and ±0.771 s, respectively. In summary, the results obtained were substantially in line with previous findings on SCG signals, adding to the evidence that FCG and SCG signals share a similar information content.
Simulations of Galaxy Formation and Large Scale Structure

In this work we use the N-body resimulation technique to address aspects of structure formation. In the first chapter we study the influence of the local environment of DM haloes on their properties. In the second chapter we address the so-called “substructure problem” which is one of the major challenges of the ΛCDM model of cosmology. We perform ultra-high resolution simulations of the assembly of a Milky Way type dark matter halo within its full cosmological context and propose a new analytical fitting formula (SWTS) which provides a better fit to the simulated Milky Way halo than the NFW or Moore profiles do. In the third chapter we use our ultra-high resolution simulations to study the possible γ-ray signal from dark matter annihilation. If such a signal was detected, the nature of the dark matter, the answer to one of the most important questions of modern cosmology, would be known. (urn:nbn:de:bvb:19-16446)
Testing for Common Cyclical Features in VAR Models with Cointegration

We consider VAR models for variables exhibiting cointegration and common cyclical features. While the presence of cointegration reduces the rank of the long-run multiplier matrix, other types of common features lead to rank reduction of the short-run dynamics. We distinguish between strong and weak form reduced rank structures. Strong form reduced rank structures analyzed by Engle and Kozicki (1993) arise when a linear combination of the first differenced variables in a cointegrated VAR is white noise whereas in the presence of a weak form reduced rank structure, linear combinations of the first differenced variables corrected for the long-run effects are white noise. The weak form has an interest in its own. For instance, it is a necessary condition for the existence of first order codependent cycles in a VAR(2). Also, it is a necessary condition for the strong form. We also consider the mixed form which combines strong and weak forms. We discuss the model selection issues which arise from this distinction and propose a simple approach to testing for these structures using a sequence of likelihood ratio test statistics. The finite sample behavior of the sequential approach is analyzed in a Monte Carlo experiment. Finally, we illustrate the relevance of the different forms of reduced ranks with an empirical analysis of US business uctuations over the period 1954-1996.
REPEATABILITY OF TRAPEZIUS MUSCLE TONE ASSESSMENT BY A MYOMETRIC METHOD

The goal of this paper is to examine the trapezius muscle tone by measuring simultaneously using Myoton-2 myometer i.e., the natural oscillation frequency, stiffness and the elasticity of the trapezius muscle. With this method, the mechanical response of the muscle, to a short applied mechanical impulse, is registered by an acceleration probe. From the acquired damped natural oscillation waveform, the frequency (Hz), the stiffness (N/m) and the logarithmic decrement of damping (characterizing tissue's elasticity) are calculated, quantifying the functional state of the muscle. The trapezius muscle on both sides of the body was tested in twenty adult women by two investigators using the Myoton-2 myometer. During the measurements, the subjects were in a relaxed sitting position. The Bland and Altman graphical test, comparing the differences of the measurements of two investigators, was used for assessing the inter-observer repeatability. The registered values for the trapezius muscle tension, stiffness and elasticity are varying between the tested subjects, but the intra-class correlation coefficient (ICC) was near 1 for three muscular properties, showing that the variation within the subject (due to the investigator) is negligible, compared with the variation between the subjects.
Ion Effective Temperatures in Polar Coronal Holes: Observations versus Ion-Cyclotron Resonance

The resonant cyclotron interaction between ion-cyclotron waves and solar wind species is considered nowadays to be a strong candidate for heating and acceleration of protons, α-particles, and heavy ions. A crucial physical parameter for determining the amount and the location of significant heating and acceleration, which the different solar wind ions receive from the waves in the frame of the ion-cyclotron mechanism, is their charge-to-mass ratio q/m. Therefore, comparisons of ion temperatures derived from spectroscopic observations and calculated by ion-cyclotron models, for ions that span a broad range in q/m, would provide a rigorous test for such models. By using an ion-cyclotron model, we calculate the effective temperatures for 10 different ions that cover the range 0.16-0.37 in q/m. Effective temperatures correspond to unresolved thermal motions and wave motions. The good agreement between our calculations, based on the specific mechanism that we employed here (ion-cyclotron resonance) and on spectroscopic observations of effective temperatures in polar coronal holes, provides support that the above mechanism accounts for the energetics and kinematics of fast solar wind heavy ions. However, such an agreement does not prove that other potential mechanisms can be excluded.
Space–time finite element computation of arterial fluid–structure interactions with patient‐specific data

The stabilized space–time fluid–structure interaction (SSTFSI) technique developed by the team for advanced flow simulation and modeling is applied to the computation of arterial fluid–structure interaction (FSI) with patient‐specific data. The SSTFSI technique is based on the deforming‐spatial‐domain/stabilized space–time formulation and is supplemented with a number of special techniques developed for arterial FSI. These include a recipe for pre‐FSI computations that improve the convergence of the FSI computations, using an estimated zero‐pressure arterial geometry, layers of refined fluid mechanics mesh near the arterial walls, and a special mapping technique for specifying the velocity profile at an inflow boundary with non‐circular shape. In the test computations reported here, we focus on a patient‐specific middle cerebral artery segment with aneurysm, where the arterial geometry is based on computed tomography images. Copyright © 2009 John Wiley & Sons, Ltd.
Novel writing technique of long and highly reflective in-fibre gratings

A novel method for writing fibre Bragg gratings is introduced. The method consists of translating a UV beam along the fibre through a phase mask. Because the phase mask and the fibre are held together, the phase of the interference pattern generated by the mask is not altered when the beam is translated along the mask. Gratings up to 1.5 cm long, limited by the mask dimensions, and with 98.5% reflection have been written in that way.