Domain Of Validity Research Articles

The Magnus effect in volleyball service by video analysis

In general, undergraduate laboratories of experimental physics do not usually have experiments designed to address Magnus effect and to measure the value of the lift coefficient. This work explores some experiments outdoors, which has the potential to arouse students’ curiosity about Magnus force by addressing three different types of volleyball services, performed by a professional beach volleyball player: spinning clockwise, counterclockwise, and low clockwise spin. In fact, due to the difference in these three ways of the volleyball service, the trajectory and the time of the travel can differ quite a lot from the movement of an oblique launch in vacuum. These differences can be predicted theoretically, although the complete solution can be obtained only numerically. However, in this work, two simplifications were adopted to provide an analytical solution: to consider only the drag force along the horizontal direction, and just weight and the Magnus force in the vertical direction. These simplifications can be justified because the oblique launches (the volleyball service) performed are close to small angles with respect to the horizontal direction. Thereby, the horizontal and vertical components of the motion equation could be solved as a function of time. The validity domain of this approach was established a posteriori by comparing the position data obtained by video analysis with the curves predicted by this simplified theoretical model. Furthermore, the drag and lift coefficients for the ball were extracted as adjusted parameters from these mathematical fits. These parameters are in good agreement with the literature.

Development of a simplified spectrophotometric method for nitrite determination in water samples

A new eco-friendly, rapid, and sensitive spectrophotometric method was developed to determine small quantities of nitrite, based on a diazotization mechanism. In an acidic solution, sulfathiazole was first diazotized with sodium nitrite, followed by adding phosphate buffer to form a yellow-colored compound, which showed maximum absorption at 450 nm, without the need for the addition of coupling agents such as N-(1-naphthyl) ethylenediamine. The effects of reagents amount and the optimal experimental conditions were examined by Central composite design. The simplified method presented a wide linear range of nitrite between 0.091 μg mL−1 and 1.47 μg mL−1, a sensitivity of 0.447 Abs mL µg−1, a determination coefficient of 0.998, and a low limit of detection of 0.053 μg mL−1. The simplified method was found to be comparable to the Griess method. It was evaluated for the measurements of nitrite using the accuracy profile approach. The validation procedure results established that 80% of the future results would be within the acceptability limit of 10% over the validation domain ranging from 0.174 μg mL−1 to 1.37 μg mL−1. The developed method was furtherly applied in the determination of nitrite using a developed paper-based analytical device that detected a nitrite concentration of 3 μg mL−1 which is considered by the World Health Organization to be the maximal permissible limit of nitrite in drinking water.

Computational approaches to Coherent Synchrotron Radiation in two and three dimensions

Coherent Synchrotron Radiation (CSR) is an important and often detrimental effect in particle accelerators. While one-dimensional models have been successfully used to design and explain the behavior of modern machines, questions remain about their domain of validity. In recent years, two- and three-dimensional models have been developed that are amenable to efficient numerical computation. This article gives an overview of CSR computation from its discovery through the present state of the art.

Towards highly accurate calculations of parity violation in chiral molecules: relativistic coupled-cluster theory including QED-effects

Parity-violating energies of the H2X2 (X = O, S, Se, Te, Po) molecules are reported, calculated as analytical expectation values at the relativistic coupled-cluster singles-and-doubles (CCSD) level using property-optimised basis sets. Radiative corrections to the was investigated using effective QED-potentials and found to reach a maximal value of 2.38% for H2Po2. However, this result depends on the choice of effective self-energy potential and may indicate limitations to their domain of validity.

Influence through mixing: hotspots as benchmarks for basic black-hole behaviour

Effective theories are being developed for fields outside black holes, often with an unusual open-system feel due to the influence of large number of degrees of freedom that lie out of reach beyond the horizon. What is often difficult when interpreting such theories is the absence of comparisons to simpler systems that share these features. We propose here such a simple model, involving a single external scalar field that mixes in a limited region of space with a ‘hotspot’ containing a large number of hot internal degrees of freedom. Since the model is at heart gaussian it can be solved explicitly, and we do so for the mode functions and correlation functions for the external field once the hotspot fields are traced out. We compare with calculations that work perturbatively in the mixing parameter, and by doing so can precisely identify its domain of validity. We also show how renormalization-group EFT methods can allow some perturbative contributions to be resummed beyond leading order, verifying the result using the exact expression.

Beyond Schr\xf6dinger-Poisson: nonrelativistic effective field theory for scalar dark matter

Massive scalar fields provide excellent dark matter candidates, whose dynamics are often explored analytically and numerically using nonrelativistic Schrödinger-Poisson (SP) equations in a cosmological context. In this paper, starting from the nonlinear and fully relativistic Klein-Gordon-Einstein (KGE) equations in an expanding universe, we provide a systematic framework for deriving the SP equations, as well as relativistic corrections to them, by integrating out ‘fast modes’ and including nonlinear metric and matter contributions. We provide explicit equations for the leading-order relativistic corrections, which provide insight into deviations from the SP equations as the system approaches the relativistic regime. Upon including the leading-order corrections, our equations are applicable beyond the domain of validity of the SP system, and are simpler to use than the full KGE case in some contexts. As a concrete application, we calculate the mass-radius relationship of solitons in scalar dark matter and accurately capture the deviations of this relationship from the SP system towards the KGE one.

The traditional approximation of rotation for rapidly rotating stars and planets

Context. The traditional approximation of rotation (TAR) is a treatment of the hydrodynamic equations of rotating and stably stratified fluids in which the action of the Coriolis acceleration along the direction of the entropy and chemical stratifications is neglected because it is weak in comparison with the buoyancy Archimedean force. This leads to the neglect of the horizontal projection of the rotation vector in the equations for the dynamics of gravito-inertial waves (GIWs). The dependent variables in those equations then become separable into radial and horizontal parts as in the non-rotating case. The TAR is built on the assumptions that the star is spherical (i.e., its centrifugal deformation is neglected) and uniformly rotating. However, it has recently been generalised to include the effects of a moderate centrifugal deformation using a perturbative approach. Aims. We study the feasibility of carrying out a new generalisation to account for the centrifugal acceleration in the case of strongly deformed uniformly and rapidly rotating stars (and planets), and to identify the validity domain of this approximation. Methods. We built a complete formalism analytically that allows the study of the dynamics of GIWs in spheroidal coordinates which take the flattening of uniformly and rapidly rotating stars into account by assuming the hierarchies of frequencies adopted within the TAR in the spherical case. Results. Using 2D stellar models, we determine the validity domain of the generalised TAR as a function of the rotation rate of the star normalised by its critical angular velocity and its pseudo-radius. Assuming the anelastic and the two-dimensional Jeffreys-Wentzel-Kramers-Brillouin approximations, we derive a generalised Laplace tidal equation for the horizontal eigenfunctions of the GIWs and their asymptotic wave periods, which can be used to probe the structure and dynamics of rotating deformed stars with asteroseismology. The generalised TAR where the centrifugal deformation of a star (or planet) is taken into account non-perturbatively allows us to identify, within the framework of 2D Evolution STEllaire en Rotation models, the validity domain of this approximation which is reduced by increasing the rate of rotation. We can affirm with a level of confidence of 90% that the TAR remains applicable in all the space domain of deformed stars rotating at a rotation rate lower than 20% of the critical rotation rate. Conclusions. A new generalisation of the TAR, which takes the centrifugal acceleration into account in a non-perturbative way, is derived. This generalisation allows us to study the detectability and the signature of the centrifugal effects on GIWs in rapidly rotating deformed stars (and planets). We found that the effects of the centrifugal acceleration in rapidly rotating early-type stars on GIWs are theoretically detectable in modern space photometry using observations from Kepler. We found also, by comparing the period spacing pattern computed with the standard and the generalised TAR, that the centrifugal acceleration affects the period spacing by increasing its values for low radial orders and by decreasing them slightly for high radial orders.

Numerical simulation of the transient hydrogen trapping process using an analytical approximation of the McNabb and Foster equation. Part 2: Domain of validity

In a previous study [1], a resolution scheme called Generalized Oriani's Approximation (GOA) was proposed to solve a transient transport and trapping problem in the Abaqus Finite Element software. This proposition was motivated by the convergence of the Finite Element problem linked to the estimation of several functions during the computation (and especially the dudt one). In this study, the GOA is shown to be able to provide an accurate estimation of the trapped concentration in transient trapping processes as soon as the time increment is small enough for two configurations: hydrogen in metals and water in polymers. An estimation of the induced error is given. The GOA approach is illustrated on a simple configuration with various trapping parameters. Last, the ability of Abaqus to converge while modeling a transient trapping and transport problem is analyzed considering several dudt: it is shown especially that its estimation based on the GOA allows the solver to efficiently converge toward the solution.

QSAR, molecular docking and ADMET properties in silico studies of novel 4,5,6,7-tetrahydrobenzo[D]-thiazol-2-Yl derivatives derived from dimedone as potent anti-tumor agents through inhibition of C-Met receptor tyrosine kinase

A quantitative structure-activity relationship (QSAR) study is performed on 48 novel 4,5,6,7-tetrahydrobenzo[D]-thiazol-2 derivatives as anticancer agents capable of inhibiting c-Met receptor tyrosine kinase. The present study is conducted using multiple linear regression, multiple nonlinear regression and artificial neural networks. Three QSAR models are developed after partitioning the database into two sets (training and test) via the k-means method. The obtained values of the correlation coefficients by the three developed QSAR models are 0.90, 0.91 and 0.92, respectively. The resulting models are validated by using the external validation, leave-one-out cross-validation, Y-randomization test, and applicability domain methods. Moreover, we evaluated the drug-likeness properties of seven selected molecules based on their observed high activity to inhibit the c-Met receptor. The results of the evaluation showed that three of the seven compounds present drug-like characteristics.In order to identify the important active sites for the inhibition of the c-Met receptor responsible for the development of cancer cell lines, the crystallized form of the Crizotinib-c-Met complex (PDB code: 2WGJ) is used. These sites are used as references in the molecular docking test of the three selected molecules to identify the most suitable molecule for use as a new c-Met inhibitor. A comparative study is conducted based on the evaluation of the predicted properties of ADMET in silico between the candidate molecule and the Crizotinib inhibitor. The comparison results show that the selected molecule can be used as new anticancer drug candidates.

The dependence of subhalo abundance matching on galaxy photometry and selection criteria

ABSTRACT Subhalo abundance matching (SHAM) is a popular technique for assigning galaxy mass or luminosity to haloes produced in N-body simulations. The method works by matching the cumulative number functions of the galaxy and halo properties, and is therefore sensitive both to the precise definitions of those properties and to the selection criteria used to define the samples. Further dependence follows when SHAM parameters are calibrated with galaxy clustering, which is known to depend strongly on the manner in which galaxies are selected. In this paper we introduce a new parametrization for SHAM and derive the best-fitting SHAM parameters as a function of various properties of the selection of the galaxy sample and of the photometric definition, including Sérsic versus Petrosian magnitudes, stellar masses versus r-band magnitudes, and optical (Sloan Digital Sky Survey) versus $\mathrm{H}\, \small {\rm I}$ (ALFALFA) selection. In each case we calculate the models’ goodness-of-fit to measurements of the projected two-point galaxy correlation function. In the optically selected samples we find strong evidence that the scatter in the galaxy–halo connection increases towards the faint end, and that AM performs better with luminosity than stellar mass. The SHAM parameters of optically and $\mathrm{H}\, \small {\rm I}$-selected galaxies are mutually exclusive, with the latter suggesting the importance of properties beyond halo mass. We provide best-fitting parameters for the SHAM galaxy–halo connection as a function of each of our input choices, extending the domain of validity of the model while reducing potential systematic error in its use.

Sub3DNet1.0: a deep-learning model for regional-scale 3D subsurface structure mapping

Abstract. This study introduces an efficient deep-learning model based on convolutional neural networks with joint autoencoder and adversarial structures for 3D subsurface mapping from 2D surface observations. The method was applied to delineate paleovalleys in an Australian desert landscape. The neural network was trained on a 6400 km2 domain by using a land surface topography as 2D input and an airborne electromagnetic (AEM)-derived probability map of paleovalley presence as 3D output. The trained neural network has a squared error <0.10 across 99 % of the training domain and produces a squared error <0.10 across 93 % of the validation domain, demonstrating that it is reliable in reconstructing 3D paleovalley patterns beyond the training area. Due to its generic structure, the neural network structure designed in this study and the training algorithm have broad application potential to construct 3D geological features (e.g., ore bodies, aquifer) from 2D land surface observations.

Interpreting the radiative properties of advanced high strength steel using the geometric optics ray-tracing approximation

This study investigates the relationship between surface topography and radiative properties of advanced high strength steel (AHSS) alloys using the geometric optics approximation (GOA) with ray tracing. Five AHSS coupons with different alloy compositions and surface topographies are investigated. The directional-hemispherical and specular reflectance of samples are measured using a UV-Vis-NIR spectrophotometer (0.25–2.5 μm) and two FTIR spectrometers (2.5-20 μm), while surface profiles used in the ray tracing model are obtained using an optical profilometer. Predictions of directional-hemispherical reflectance are consistent with the experimental data when the surface parameters and incident wavelengths are within the valid GOA domain. Reflectance predictions in the specular direction are also in line with the measurements when the roughness parameters are in the specular approximation domain.

Obey validity limits of data-driven models through topological data analysis and one-class classification

Data-driven models are becoming increasingly popular in engineering, on their own or in combination with mechanistic models. Commonly, the trained models are subsequently used in model-based optimization of design and/or operation of processes. Thus, it is critical to ensure that data-driven models are not evaluated outside their validity domain during process optimization. We propose a method to learn this validity domain and encode it as constraints in process optimization. We first perform a topological data analysis using persistent homology identifying potential holes or separated clusters in the training data. In case clusters or holes are identified, we train a one-class classifier, i.e., a one-class support vector machine, on the training data domain and encode it as constraints in the subsequent process optimization. Otherwise, we construct the convex hull of the data and encode it as constraints. We finally perform deterministic global process optimization with the data-driven models subject to their respective validity constraints. To ensure computational tractability, we develop a reduced-space formulation for trained one-class support vector machines and show that our formulation outperforms common full-space formulations by a factor of over 3000, making it a viable tool for engineering applications. The method is ready-to-use and available open-source as part of our MeLOn toolbox (https://git.rwth-aachen.de/avt.svt/public/MeLOn).

A sequence of experiments and models to grasp the strange nature of light

We present a sequence of activities designed to stimulate students to reflect on the nature of light and on the different models (ray, wave, classical and quantum particles) used in teaching and learning optics. These activities are also aimed to help students in evaluating the profound meaning of the “correspondence principle” and develop their own views about some aspects of nature of science even if it is not taught explicitly. In fact, optics is a paradigmatic case where different scientific models are proposed in the University (and high school) courses. Even the oldest of these models have non empty domains of validity and both Maxwellian electromagnetism and geometrical optics are largely still used in the Physics curricula. As a consequence students are often puzzled, and think that each of these theories works in a specific domain, without any connection one with the other. Thus we investigate students’ mental models of light in different contexts and we show how they develop hybrid models in explaining different phenomena or use models inconsistently.

Timescale-Based Frozen Nonadiabatic Flamelet Combustion Modeling for Rocket Engine Thrust Chambers

The present research work introduces a novel combustion model formulation based on the flamelet concept suitable to investigate characteristic flow conditions in rocket engine thrust chambers. The new approach extends the validity domain of existing flamelet models to fully cover the observed flow conditions by incorporating kinetic rate effects into a state-of-the-art nonadiabatic flamelet manifold. This enables a transition between the fluid dynamic and reaction-rate-dominated combustion regimes, depending on the local Damköhler number of the numerical solution field. The approach is investigated based on a representative rocket engine test case focusing on highly nonadiabatic and de Laval nozzle flow conditions for the propellant combination methane-oxygen. Covering a range of propellant mixture ratios associated with significant variations of the underlying chemical effects, three flamelet combustion-modeling approaches of different manifold complexity are compared to high-fidelity laminar finite rate results based on the full chemical reaction mechanism. The obtained data show that the proposed model formulation is able to deliver a notably higher accuracy in the numerical prediction compared to the existing modeling approaches while retaining high computational efficiency to meet industrial design requirements.

Closed Analytic Formulas for the Approximation of the Legendre Complete Elliptic Integrals of the First and Second Kinds

The author proposes two sets of closedanalytic functions for the approximate calculus of thecomplete elliptic integrals of the first and secondkinds in the normal form due to Legendre, therespective expressions having a remarkablesimplicity and accuracy. The special usefulness of theproposed formulas consists in that they allowperforming the analytic study of variation of thefunctions in which they appear, by using thederivatives. Comparative tables including theapproximate values obtained by applying the two setsof formulas and the exact values, reproduced fromspecial functions tables are given (all versus therespective elliptic integrals modulus, k = sin ). It is tobe noticed that both sets of approximate formulas aregiven neither by spline nor by regression functions,but by asymptotic expansions, the identity with theexact functions being accomplished for the left end k= 0 ( = 0) of the domain. As one can see, the secondset of functions, although something more intricate,gives more accurate values than the first one andextends itself more closely to the right end k = 1 ( =90) of the domain. For reasons of accuracy, it isrecommended to use the first set until  = 70.5 only,and if it is necessary a better accuracy or a greaterupper limit of the validity domain, to use the secondset, but on no account beyond  = 88.2.

An illustration‐based developmental motor screening questionnaire for young children: Development and a Rasch analysis

AbstractThis study aimed to develop an illustration‐based developmental motor screening questionnaire (DMSQi) for young children and examined its psychometric properties. 463 young children and their caregivers were collected and received the DMSQi assessment. DMSQi is made up of two domains. The gross motor (GM) domain includes body coordination and stability/mobility subdomains. The fine motor (FM) domain includes visual motor integration and hand grasp/manipulation subdomains. The internal consistency (Cronbach's α) and test–retest reliabilities (ICCs) of DMSQi were 0.88–0.98 and 0.85–0.95, respectively. For concurrent validity, the GM and FM domains of DMSQi were highly correlated with the corresponding domains of Peabody Developmental Motor Scale, second edition (r = 0.85–0.95). DMSQi had good discriminant validity for age (p < .001). Most items (96%) were fitted and the item difficulty was from −7 to 5 scaled by Rasch analysis. DMSQi is easy, quick, and culture‐specific. It has good reliability, validity, and item fit for assessing the motor development of young children.

Frame dragging and the Hong-Ou-Mandel dip: Gravitational effects in multiphoton interference

We investigate the Hong-Ou-Mandel (HOM) effect $-$ a two-photon quantum-interference effect $-$ in the space-time of a rotating spherical mass. In particular, we analyze a common-path HOM setup restricted to the surface of the earth and show that, in principle, general-relativistic frame-dragging induces observable shifts in the HOM dip. For completeness and correspondence with current literature, we also analyze the emergence of gravitational time-dilation effects in HOM interference, for a dual-arm configuration. The formalism thus presented establishes a basis for encoding general-relativistic effects into local, multi-photon, quantum-interference experiments. Demonstration of these instances would signify genuine observations of quantum and general relativistic effects, in tandem, and would also extend the domain of validity of general relativity, to the arena of quantized electromagnetic fields.

Enhanced modal matching formulation for a cost-efficient computation of the acoustical properties of multi-layer perforated and micro-perforated partitions

As rigidly backed micro-perforated panels (MPPs) are Helmholtz-type absorbers, their performance is typically limited to narrow frequency bands. The use of multi-layer or multi-array partitions has been widely studied to extend their absorption over a broader range. Optimal selection often requires combination of macro and micro-perforated panels constitutive of the overall partition. However, it is difficult to find a unified impedance model that may account for the whole range of hole diameters variations encountered in an optimization process. In this study, an enhanced multi-modal (EMM) formulation is developed that overcomes limitations for the domain of validity of the MPP parameters. It provides a unit cell transfer impedance that accounts for visco-thermal dissipation and high-order evanescent modes both within the perforation and at the panel walls. It can be used as a Robin-type visco-thermal boundary condition in a pure Acoustic finite element model (FEM) of a complex micro-/macro-perforated structure. This approach leads to a mixed analytical-numerical approach with a much lower computational cost than a full visco-thermal Acoustic FEM model. The inclusion of hole or panel interaction effects is then achieved through the acoustic or structural FEM parts.

Looking Out For (White) Australia

Abstract. We conceptualized and developed a measure of right-wing protective popular nationalism (RWPPN) – a specific form of popular nationalism where people seek to protect the national culture from outgroup influences. RWPPN is derived from a sociological analysis of right-wing popular nationalism in Australia and is theoretically related to several key psychological constructs, including right-wing authoritarianism (RWA), social dominance orientation (SDO), and symbolic threat. We conducted two surveys using nationally representative samples of Australian citizens. In study 1 ( n = 657), participants completed measures of RWPPN and related constructs. Exploratory and confirmatory factor analysis resulted in a 10-item scale. Construct validity was tested and confirmed across divergent, convergent, predictive, and concurrent validation domains. Additional convergent validation with RWA and SDO was tested in study 2 ( n = 316). Together, RWPPN was found to relate to expressions of national identity, prejudice, perceived outgroup threat, opposition to multiculturalism, and aggressive tendencies toward ethnic minorities. These effects remained significant when controlling for nationalism (measured as a concern for national superiority) and blind patriotism. In study 2, the effect on aggressive tendencies held when controlling for RWA and SDO and RWPPN mediated the relationship between RWA and aggressive tendencies. Reflecting the conservative nature of Australian popular nationalism, RWPPN correlated with right-wing political alignment. The research was conducted in Australia, but given the rise in right-wing populism internationally, RWPPN may be a phenomenon in other countries. Therefore, this paper offers a new construct and scale to investigate it in Australia and internationally.