Miracle-dz/UniFAR-FTUs huggingface dataset:
Source Width of Frontal Phantom Sources: Perception, Measurement, and Modeling

Phantom sources are known to be perceived similar to real sound sources but with some differences. One of the differences is an increase of the perceived source width. This article discusses the perception, measurement, and modeling of source width for frontal phantom sources with different symmetrical arrangements of up to three active loudspeakers. The perceived source width is evaluated on the basis of a listening test. The test results are compared to technical measures that are applied in room acoustics: the inter-aural cross correlation coefficient (IACC) and the lateral energy fraction (LF). Adaptation of the latter measure makes it possible to predict the results by considering simultaneous sound incidence. Finally, a simple model is presented for the prediction of the perceived source width that does not require acoustic measurements as it is solely based on the loudspeaker directions and gains.
Corporate governance in immigrant-founded entrepreneurial firms: ownership heterogeneity and firm performance

ABSTRACT Drawing from resource dependence theory and the faultlines perspective, this study examines how ownership heterogeneity affects firm performance in the understudied context of entrepreneurial firms founded by immigrants. We find that investment by venture capitalists (VCs) is associated with immigrant-founded entrepreneurial firms being less profitable during their infancy stage. Our results also reveal that the presence of a native-born co-owner has a negative effect on performance for these entrepreneurial firms. This study suggests that immigrant entrepreneurs be more cautious about the costs and benefits of seeking resources from VCs and partnering with native co-owners. Further, seeking capital from alternative sources and employing native talent and expertise in terms of business advisers or executive managers may be effective alternative approaches for immigrant entrepreneurs.
FDTD Simulation of Near-Field Radiative Heat Transfer between Thin Films Supporting Surface Phonon Polaritons: Lessons Learned

Abstract We present the numerical simulation, using the finite difference time domain (FDTD) method, of the radiative heat transfer between two thin SiC slabs. We aim to explore the ability of the FDTD method to reproduce the analytical results for the Surface Phonon Polariton (SPhP) assisted near field radiative energy transfer between two SiC slabs separated by a nano/micro-metric vacuum gap. In this regard, we describe the key challenges that must be addressed for simulating general near-field radiative energy transfer problems using the FDTD method. FDTD is a powerful technique for simulating the near-field radiative energy transfer because it allows simulating arbitrary shaped nano-structured bodies, like photonic crystals, for which an analytical solution is not readily obtained. Key words : Near-Field Radiative Heat Transfer, Fluctuation Electrodynamics, Thermal Radiation, Surface Phonon Polariton, FDTD 1. Introduction When two bodies are located at short distance (in the nano/micro scale) the evanescent modes can tunnel between each other and contribute to the radiative energy transfer, which can exceed the black body radiation by several orders of magnitude [1–3]. Besides, at nano-metric distance, the excitation of surface plasmon polaritons (SPP) in metals or surface phonon polaritons (SPhP) in polar materials, produce even further enhancement of the radiative energy transfer at the resonance frequencies [4–7], allowing for quasi-monochromatic near-field radiative heat transfer. These phenomena have got rising attention in the recent years due to the strong development of nano/micro-technologies, where near-field effects have to be considered in the thermal analysis. Some of the key applications that has been proposed so far are nano-lithography [8], near-field imaging [9], thermophotonic heat pumping [10], and thermophotovoltaic (TPV) energy conversion [3], [11–16] . Most of the theoretical studies on near-field radiative heat transfer presented so far are based on fluctuation electrodynamics theory [17–19]. This theoretical framework assumes that the origins of thermal radiation are the fluctuating currents originated by the random motion of charges within the material, and the problem can be solved analytically by means of the Green’s functions [20], which provides the spatial transfer function between current sources and the corresponding electro-magnetic fields in a given location of the space. However, the complexity of Green’s function formalism limits the theoretical development on near-field radiative heat transfer to relatively simple geometries; mainly infinite extended multilayered structures [19], for which a closed analytical solution is available.
LDV Measurements of the Flow Field in the Nozzle Region of a Confined Double Annular Burner

A database for the complex turbulent flow of a confined double annular burner in cold conditions is presented here, In the region close to the exit of the annular nozzles LDV measurements at 5515 grid points in the meridional plane were conducted. At each measurement position, validated data for 3000-16,000 particles were recorded, and the mean axial and radial velocities, axial and radial turbulence intensity and Reynolds stresses were computed. The resulting mean flow field is axisymmetric within an uncertainty of 2 percent. The contour plots of turbulent quantities on the fine grid, as well as the streamlines based on the mean flow field, are presented for the flow.
Unified modelling of near-cathode plasma layers in high-pressure arc discharges

A model of a near-cathode region in high-pressure arc discharges is developed in the framework of the hydrodynamic (diffusion) approximation. Governing equations are solved numerically in 1D without any further simplifications, in particular, without explicitly dividing the near-cathode region into a space-charge sheath and a quasi-neutral plasma. Results of numerical simulation are reported for a very high-pressure mercury arc and an atmospheric-pressure argon arc. Physical mechanisms dominating different sections of the near-cathode region are identified. It is shown that the near-cathode space-charge sheath is of primary importance under conditions of practical interest. Physical bases of simplified models of the near-cathode region in high-pressure arc discharges are analysed. A comparison of results given by the present model with those given by a simplified model has revealed qualitative agreement; the agreement is not only qualitative but also quantitative in the case of an atmospheric-pressure argon plasma at moderate values of the near-cathode voltage drop. The modelling data are compared with results of spectroscopic measurements of the electron temperature and density in the near-cathode region.
An accurate method for the calculation of singular integrals arising in time-domain integral equation analysis of electromagnetic scattering

An accurate method for the evaluation of the Cauchy principal value integrals arising in time-domain electromagnetic wave scattering is presented. This is applied to a boundary integral equation (BIE) method employing quadratic curvilinear surface elements where such singularities do not vanish (as they generally do when simpler but less accurate discretizations are employed). The technique involves weakening the singularity in the original kernel to a degree where conventional integration methods may be employed and transforming the strong singularity to a line integral in a form which allows cancellation of its singular components. The effectiveness of the method is demonstrated by scattering calculations on a variety of targets and the computational cost of the approach is trivial.
Eigenpath Following for Systems with Symmetric Complex-Valued Stiffness Matrices

A vibration analysis of a structure with joints is performed. The simulation is conducted with finite element software capable of performing a numeric modal analysis with hysteretic damping assumption. The joints are modeled with thin layer elements, representing dissipation and stiffness of the joints. The matrices describing the system consist of the mass, as well as real and complex-valued stiffness matrices. If the eigenvalues of this system are found in one step, due to the mode crossing occurring for the closely spaced modes, it is difficult and time consuming to assign calculated modal damping factors to the corresponding undamped eigenvalues. In order to avoid this problem, an eigenvalue following method is used. The outcome of the solution is the graphical presentation of continuous eigenvalue paths, showing the change in the eigenvalues from the undamped to the fully damped case. For every undamped eigenvalue exists its equivalent eigenfrequency and damping factor that can be used for further numerical analysis. In scope of this article a Predictor-Corrector and a Rayleigh-Quotient Iteration algorithms are applied to the problem. The algorithms are tested specifically on the type of matrices resulting from the weakly damped hysteretic formulation arising from the simulation of metallic structures with joints.
Association of coffee consumption pattern and metabolic syndrome among middle-aged and older adults: A cross-sectional study

Objectives The association between coffee consumption and the risk of metabolic syndrome (MetS) remains inconsistent. The aim of this study was to evaluate the association between coffee intake and components of MetS. Method A cross-sectional survey including 1,719 adults was conducted in Guangdong, China. Data on age, gender, education level, marriage status, body mass index (BMI), current smoking and drinking status and breakfast habit, coffee consumption type, and daily servings were derived based on 2-day, 24-h recall. MetS were assessed according to the International Diabetes Federation definition. Multivariable logistic regression was conducted to examine the association between the coffee consumption type, daily servings, and the components of MetS. Results Regardless of the coffee type, compared with non-coffee consumers, coffee consumers had higher odds ratios (ORs) of the elevated fasting blood glucose (FBG) in both men [OR: 3.590; 95% confidence intervals (CI): 2.891–4.457] and women (OR: 3.590; 95% CI: 2.891–4.457). In women, the risk of elevated blood pressure (BP) was 0.553 times (OR: 0.553; 95% CI: 0.372–0.821, P = 0.004) for people who drank total coffee > 1 serving/day than for non-coffee drinkers. Conclusion In conclusion, regardless of type, coffee intake is associated with an increased prevalence of FBG in both men and women, but has a protective effect on hypertension only in women.
Coaxial Low-Pass Filter Design and Manufacture

In this study, a low-pass filter with coaxial transmission lines is designed and produced. The objective for designing a coaxial low-pass filter was to utilize both low-loss transmission and high breakdown voltage capability for high power microwave applications to enable the suppression of the second harmonic of the 4.4-6 GHz C-Band (C-Band was selected as a proof of concept) signals with minimal insertion loss. Microwave and 3D electromagnetic simulators were used in the filter design. The design was started by establishing an 11 th order Chebyshev low-pass filter prototype giving 0.05 dB ripple. Based on this prototype, a filter circuit consisting of capacitors and inductors as lumped elements was designed. The low and high impedances to be selected for the stepped impedance method, which is the basis of the transition to coaxial transmission lines, were decided and the most suitable impedances for manufacturing was determined. The filter using these impedances and designed with stepped impedance lines was transformed into the filter in which coaxial transmission lines are used. Coaxial transmission lines in the low-pass filter circuit consist of conductors with an insulating material in between. While the insulating material is selected as air in the high impedance sections of the transmission lines, it is PTFE (Polytetrafluoroethylene) with an insulating constant of 2.1 in the low impedance sections. The designed filter was manufactured. The basic properties of the manufactured filter were characterized by using RF measuring devices and compared with the designed filter. The measurements results proved that the frequency responses of the designed filter and the produced filter were very close to each other. Namely, a low-pass filter with a cutoff frequency of 6 GHz, a sharp suppression of about 45 dB at the stopband of 9 GHz and a return loss of 20 dB was designed and produced by using coaxial transmission lines. The novelty in our work can be stated that the power handling capability is increased by two techniques. The first one is that the highest transmission line radius preventing the higher order mode excitations is used to decrease the conductor loss. Teflon is covered around the low impedance lines to enhance the dielectric breakdown capability. Teflon inclusion is also used to decrease the practical low impedance level that improves the filter characteristics.
On the flow in channels when rigid obstacles are placed in the stream

A previous paper drew attention to the collective importance of three physical quantities Q, R, S associated with ideal fluid flow in a horizontal channel. Invariability of these quantities at different cross-sections of the flow implies respectively conservation of flow rate, energy and momentum; and their values determine a wave-train uniquely. The properties of Q, R, S are recalled in the present paper to account for the various effects of lowering a rigid obstacle into a stream. The conditions giving rise to dissimilar types of flow are examined; in particular, the circumstances causing stationary waves on the downstream side are clearly distinguished from those under which the receding stream assumes a uniform ‘supercritical’ state. A well-known result in the theory of the solitary wave is shown to apply to the receding stream even when the extreme conditions for the wave are exceeded; although it fails to account for a region close to the obstacle where the curvature of the streamlines becomes large. In passing, a feature of the theory is shown to bear on the practical problem of producing a uniform stream. Precise calculations are made for the flow under a vertical sluice-gate and under an inclined plane. To account for the region near the bottom edge of the sluice-gate, a method based on conformal transformation is used whereby an unknown curve in the hodograph plane is approximated by an arc of an ellipse. The accuracy of the results is more than sufficient for practical purposes, and they compare favourably with solutions previously obtained by relaxation methods. A number of experiments with water streams are described.
Approximate controllability of stochastic delay differential systems driven by Poisson jumps with instantaneous and noninstantaneous impulses

Control systems in which instantaneous and noninstantaneous impulses occur simultaneously are difficult to handle. In this article, we investigate the solvability and approximate controllability for a new category of stochastic differential equations steered by Poisson jumps with instantaneous and noninstantaneous impulses. Utilizing the theory of fundamental solution, stochastic analysis, the measure of noncompactness, and the fixed‐point approach, we establish the presence of a mild solution for the proposed system. We have also constructed a new set of sufficient constraints that assures approximate controllability of the considered system. Next, we discuss the existence of a solution and approximate controllability for an impulsive deterministic control system in which the nonlinear term contains spatial derivatives. Lastly, two examples are presented to encapsulate the abstract results.
Modelling of flow through the circle of Willis and cerebral vasculature

The blood flow through the circle of Willis was modelled by coupling a Computational Fluid Dynamics (CFD) model of the circle of Willis with a branching tree model of the cerebral vasculature. The cerebral small vascular networks, which often cannot be accurately obtained by medical imaging, were modelled using a branching tree fractal model that accurately simulated the cerebral vasculature geometries and flow. This provided realistic mass flow boundary conditions for the outlet arteries of the circle of Willis. CFD was used to model the three-dimensional transient flow through a simplified and a patient-specific circle of Willis. The patient specific geometry was obtained directly from Computed Tomography (CT) images. A pipe network model was also used to predict the flow through the simplified circle of Willis and the predictions for the flow rates were within 4% of the CFD predictions. The coupled CFD and branching tree model provided useful insight into the variation of the flow through the circle of Willis.
Review of the psychometric properties of the Patient Health Questionnaire-9 (PHQ-9) Spanish version in a sample of Puerto Rican workers

Background This study aimed to examine the internal structure and assess the psychometric properties of the Patient Health Questionnaire (PHQ-9) in a Puerto Rican sample of workers. This instrument is a nine-item questionnaire, which was conceptualized as a unidimensional structure; however, there are mixed results regarding this internal structure. This measure is used in the occupational health psychology context in organizations in Puerto Rico; nevertheless, there is little evidence of its psychometric properties with samples of workers. Materials and methods A total of 955 samples from two different study samples were used in this cross-sectional study design in which the PHQ-9 was used. We conducted confirmatory factor analysis, bifactor analysis, and random intercept item factor analysis to examine the internal structure of the PHQ-9. Moreover, a two-factor model was examined by randomly assigning items to the two factors. Measurement invariance across sex and the relationship with other constructs were examined. Results The best-fitted model was the bifactor model followed by the random intercept item factor. The five sets of two-factor models with items randomly assigned obtained acceptable and similar fit indices regardless of the items. Conclusion The results suggest that the PHQ-9 appears to be a reliable and valid instrument to measure depression. The more parsimonious interpretation of its scores, for now, is a unidimensional structure. Comparison across sex appears to be useful in occupational health psychology research settings since the results suggest that the PHQ-9 is invariant regarding this variable.
Analytical and numerical analysis of phase and amplitude errors in the performance of arrayed waveguide gratings

The closed expression of the mean power transfer function for an arrayed waveguide grating (AWG), taking into account fabrication errors, is presented. Comparison with numerical simulations using a previous Fourier optics modeling show good agreement. The procedure to predict the AWG floor level using the numerical modeling is presented and checked against the analytical derived expressions.
Minimum effort dead‐beat control of linear servomechanisms with ripple‐free response

A new and systematic approach to the problem of minimum effort ripple‐free dead‐beat (EFRFDB) control of the step response of a linear servomechanism is presented. There is specified a set of admissible discrete error feedback controllers, complying with general conditions for the design of ripple‐free dead‐beat (RFDB) controllers, regardless of the introduced degree of freedom, defined as the number of steps exceeding their minimum number. The solution is unique for the minimum number of steps, while their increase enables one to make an optimal choice from a competitive set of controllers via their parametrization in a finite‐dimensional space. As an objective function, Chebyshev's norm of an arbitrarily chosen linear projection of the control variable was chosen. There has been elaborated a new, efficient algorithm for all stable systems of the given class with an arbitrary degree of freedom. A parametrized solution in a finite space of polynomials is obtained through the solution of a standard problem of mathematical programming which simultaneously yields the solution of a total position change maximization of servomechanism provided that a required number of steps and control effort limitation are given. A problem formulated in this way is consecutively used in solving the time‐optimal (minimum‐step) control of a servomechanism to a given steady‐state position with a specified limitation on control effort. The effect of EFRFDB control on the example of a linear servomechanism with torsion spring shaft, with the criterions of control effort and control difference effort, is illustrated and analysed. Copyright © 2001 John Wiley & Sons, Ltd.
Design of Forcing Functions for the Identification of Human Control Behavior

Human control behavior, as exercised during vehicle or aircraft control, can be identified by applying forcing functions with a specific frequency content to excite the human control system. The presence of these forcing functions may affect human control behavior as well, an effect which is not well-understood and might considerably affect the result of experiments. Common metrics, such as spectral shape and bandwidth, have been shown to be insufficient in predicting the forcing function's effect on human control behavior. This paper investigates the effect of forcing function phase on the control behavior, as well as the effect of the forcing function frequencies at which power is present, within a fixed spectral shape. These effects were tested in a human-in-the-loop compensatory tracking experiment. Our experiment showed that the effects ofthe frequencies were substantial. For this reason, a new metric was proposed to better predict the effects of forcing functions on the human control behavior, and to allow comparison between forcing functions with different spectral shapes and frequency contents. The metric considers the variance of the signal's derivatives. To test the validity of the metric, forcing functions with equal derivative variances were used in a compensatory tracking experiment. The outcome of the experiment reveals that the resulting behavior indeed can be considered equal when the variances are equal, even when the forcing function spectral shapes are considerably different.