Elementary Tests Research Articles

Barotropic equations of state in 4D Einstein-Maxwell-Gauss-Bonnet stellar distributions

We investigate the role of a linear barotropic equation of state (p=γρ) on the structure of charged stars under higher curvature effects induced by the Gauss-Bonnet invariants in 4 dimensions. Assuming a constant spatially directed potential which gives isothermal behavior in the standard theory, the master equation is solved in terms of hypergeometric functions but a viable model could not be constructed. Setting the temporal potential to a constant, comparable to the defective Einstein static universe, interestingly admits nontrivial nonconstant exact solutions due to the higher curvature terms unlike in general relativity. Next the existence of a one-parameter group of conformal motions in the spacetime geometry was investigated. The master differential equation is solvable exactly in implicit form and explicit solutions are found for special cases. For the case of a stiff fluid p=ρ a stellar model with pleasing physical attributes is found. When the potential is assumed to vary linearly with the radius, an exact incoherent radiation model p=13ρ emerges. The physical properties of both these solutions are analyzed comprehensively with the aid of graphical plots in conjunction with suitably defined parameter spaces. It was found that both exact models passed elementary astrophysical tests for physical plausibility.

MONOGENIC QUARTIC POLYNOMIALS AND THEIR GALOIS GROUPS

Abstract A monic polynomial $f(x)\in {\mathbb Z}[x]$ of degree N is called monogenic if $f(x)$ is irreducible over ${\mathbb Q}$ and $\{1,\theta ,\theta ^2,\ldots ,\theta ^{N-1}\}$ is a basis for the ring of integers of ${\mathbb Q}(\theta )$ , where $f(\theta )=0$ . We use the classification of the Galois groups of quartic polynomials, due to Kappe and Warren [‘An elementary test for the Galois group of a quartic polynomial’, Amer. Math. Monthly96(2) (1989), 133–137], to investigate the existence of infinite collections of monogenic quartic polynomials having a prescribed Galois group, such that each member of the collection generates a distinct quartic field. With the exception of the cyclic case, we provide such an infinite single-parameter collection for each possible Galois group. We believe these examples are new and we provide evidence to support this belief by showing that they are distinct from other infinite collections in the literature. Finally, we devote a separate section to the cyclic case.

Development and deployment of an adaptive national elementary reading screening test

Increasingly over the past decade, there has been a demand of more thorough documentation of the quality of reading assessments. Yet, available documentation of high-quality measures are often restricted to general framework descriptions providing psychometric information as a token of test quality. In a modern view of validity, understanding what is being measured and how scores are calculated is a prerequisite for good interpretation and use of test scores. The present article aims to document the research and development process of a national adaptive screening test for reading difficulties, in which the envisioned interpretation and use of test scores is guiding the work. Given the mandatory nature of this test the sample consist of 49,828 third grade students aged 8. Significant outcomes from this design process involve detailed information on: (a) choice of sub-tests and item formats, (b) selection of high quality items, (c) choice and design of adaptive model, and finally, a statement on the challenges that are still to be met for such a test to function optimally. The present paper is among the first to, in an open and detailed manner, describe the development process as well as qualities and challenges of an adaptive reading screening test for students of this young age.

Numerical modeling of systems based on SMA wires and pulleys: A finite element formulation within the Arbitrary Lagrangian–Eulerian framework

Thanks to their properties of superelasticity and shape memory effects, SMA wires are often considered for the design of damping devices or actuators coupled to pulleys. In order to dimension such devices for commercialization, it is necessary to develop reliable, robust and fast numerical tools. To this end, simplifying the management of the wire/pulley contact using an Arbitrary Lagrangian–Eulerian (ALE) formulation is an original and effective solution. In this work, the wires are modeled by three-dimensional truss thermo-mechanical finite elements associated with a superelastic law. For each node, the curvilinear abscissa is used as an additional degree of freedom in order to deal with material flow from one element to another. After presenting the ALE formalism and the necessary precautions (advection of variables), as well as the material behavior and thermo-mechanical contact laws at the pulleys, elementary validation tests are studied. Finally, two devices taken from the literature are modeled using the ALE formalism. The results obtained demonstrate the relevance and effectiveness of the approach adopted, as well as the importance of not neglecting friction at the pulleys and thermal effects on the material mechanical response.

Evaluasi Pembelajaran Menyimak di Kelas Tinggi

Listening skills also influence students' writing skills. In every writing lesson, students need inspiration through information or stories they hear from teachers or other people. Therefore, listening skills are correlated with writing skills. Furthermore, the connection between listening skills and reading lies in the pronunciation of the sound of a word. Without listening, students cannot identify the sounds of words so they may not be able to read. The important role of evaluating language learning in elementary schools is to become the basis for decision making and policy making, measuring student achievement, evaluating the curriculum, accrediting schools, monitoring the use of public funds, improving educational materials and programs. Learning evaluation functions for development and accreditation. In conducting language learning evaluations in elementary schools, test and non-test techniques can be used. The purpose of assessing listening skills learning is to find out whether everything experienced by students in learning is in accordance with basic competencies, especially indicators. Learning evaluation is divided into four types of evaluation, namely, Formative Evaluation, Summative Evaluation, Diagnostic Evaluation and Placement Evaluation.

초등학생 문해력 진단도구 개발과 타당화

초등학생 문해력 진단도구 개발과 타당화

Geographic isolation and learning: Evidence from rural schools in Colombia

Rural schools are usually behind in terms of learning, and this could be partly related to geographical isolation. We explore this hypothesis, assessing the causal effect of the distance between schools, towns, and State capitals on elementary school test scores. We use granular administrative records from Colombia and estimate spatial regression discontinuity models. Results indicate that the distance to both towns and State capitals negatively affect students test scores. The differences in educational inputs, such as teachers education attainment and contract stability, partly explain these gaps. A program providing monetary incentives to teachers in difficult access areas fails to attenuate the isolation effect.

Using Interpretable Machine Learning for Differential Item Functioning Detection in Psychometric Tests.

This study presents a novel method to investigate test fairness and differential item functioning combining psychometrics and machine learning. Test unfairness manifests itself in systematic and demographically imbalanced influences of confounding constructs on residual variances in psychometric modeling. Our method aims to account for resulting complex relationships between response patterns and demographic attributes. Specifically, it measures the importance of individual test items, and latent ability scores in comparison to a random baseline variable when predicting demographic characteristics. We conducted a simulation study to examine the functionality of our method under various conditions such as linear and complex impact, unfairness and varying number of factors, unfair items, and varying test length. We found that our method detects unfair items as reliably as Mantel-Haenszel statistics or logistic regression analyses but generalizes to multidimensional scales in a straight forward manner. To apply the method, we used random forests to predict migration backgrounds from ability scores and single items of an elementary school reading comprehension test. One item was found to be unfair according to all proposed decision criteria. Further analysis of the item's content provided plausible explanations for this finding. Analysis code is available at: https://osf.io/s57rw/?view_only=47a3564028d64758982730c6d9c6c547.

A sequential inverse approach for draping simulations of woven fabrics with anisotropic hyperelastic behavior laws

Simulations of the draping of woven fabrics for the manufacturing of composite parts with complex geometries rely on either the geometrical method, which does not consider the shearing stresses and the external forces, or incremental finite element analyses, which require substantial CPU times. In this study, the one-step finite element method, also referred as the inverse approach in the literature, commonly used for sheet metal forming, is adapted to the woven fabric draping. The main issue of one-step simulations is the convergence of the Newton–Raphson scheme, which relies on an appropriate initial solution estimation. This problem is addressed by a sequential initial solution estimation, based on successive sub-problems with increasing difficulty up to the actual one. Applications of the proposed method on elementary test cases show fast and robust convergence, with CPU times comparable to those of the geometrical method. The proposed method is able to predict the influence of external forces and material hyperelastic mechanical behavior laws on the strain components of interest of woven fabrics, such as the shearing angles between yarns and the yarn elongations.

Table Tennis Forehand Drive Learning Model for Application based Elementary School Students

This research produces a learning model for table tennis forehand drive strokes for upper elementary school students and tests the effectiveness of an application-based table tennis forehand stroke skill model for upper elementary school students. The research approach and method for this table tennis Forehand drive stroke skill learning model uses the ADDIE (Analysis, Design, Development, Implementation and Evaluation) research and development model. The subjects involved in this research were 34. The subjects of this research were upper elementary school students. The data analysis technique was created by conducting a pretest and posttest using a forehand drive stroke skill movement instrument. The results are analyzed, the point is to find out whether there is a percentage increase in skills through the learning model given to students. Based on the results of the analysis, it was found that there was an increase in the ability of table tennis forehand drive strokes for elementary school IV students after implementing the forehand drive movement learning model. The results obtained were 6.41% pre-test and 8.65% post-test.

Comparative analysis of knowledge bases: system architecture

When comparing similar knowledge bases the question arises: what situations produce different conclusions in these bases? The task of comparing knowledge bases can emerge in different domains. For example, in legal domain, it is sometimes essential to compare different versions of a legal act or similar legal acts of different countries. The article presents an architecture of the system designed for the automated comparing of knowledge bases. The architecture implements the method of comparing based on the construction of elementary test situations.

Modeling crushable soils incorporating density effects via coordination number

A rational constitutive model of crushable soils is proposed based on a novel evolution law for the grading index, which incorporates the effect of packing density on the particle crushing phenomena through the coordination number as an intermediate variable. The evolution law of the grading index reasonably combines the increase in the coordination number due to an increase in packing density; and the increase in the crushing resistance due to the increase in the coordination number. The effect of particle crushing on the stress–strain response is incorporated by lowering the critical state specific volume with the changing grading due to crushing. The validity of the proposed constitutive model was verified with an extensive series of elementary tests and DEM. The proposed model properly predicted two seemingly contradictory experimental evidence for crushable soils that: densely packed soil exhibits lesser crushing than loosely packed one under the same effective stress paths; densely packed soil is more likely to crush than loosely packed one when it is sheared. This approach can predict the stress–strain response of crushable soils under different packing densities and stress paths, offering valuable insights for comprehending the crushing responses.

Community-Level Incarceration Rates and the Quality of Local Education Systems in North Carolina

Incarcerationis an important area of study in the United States, which incarcerates morepeople than any other country. Indirect evidence suggests that community levelincarceration rates are related to local school systems. Using a sample of2,145 North Carolina census tracts, we estimate a structural equation model oftract level incarceration rates to address two sets of research questions. First,are elementary school test scoresand student-teacher ratios directly related to local incarceration rates? Second,are elementary school test scores and student-teacher ratios indirectly relatedto local incarceration rates, mediated through other local factors? We find that both have a direct effect onincarceration rates, and that test scores have an indirect effect onincarceration through three of the tested mediating factors, which areemployment outcomes, poverty, and family structure. Our results suggest that tobetter understand patterns of community level incarceration rates,understanding local school systems’ role is crucial.

Protocolo diagnóstico y tratamiento de las crisis hipertensivas

Hypertensive crises are clinical situations which involve an acute rise in blood pressure (BP) that require swift diagnosis and appropriate treatment to prevent increasing organic dysfunction. The clinical history, physical examination and elementary complementary tests will allow us to differentiate between two entities: hypertensive urgency and emergency. A hypertensive urgency is defined as raised BP without injury to a target organ. The therapeutic target will be to gradually reduce the BP in the following days using orally administered drugs with a long half-life. A hypertensive emergency involves raised BP associated with injury to a target organ (the heart, kidneys or cerebrovascular) and it is a life-threatening risk for the patient. It requires immediate intravenous antihypertensive treatment, continuous haemodynamic monitoring and a rapid partial fall in BP.

Effects of Test Mode and Medium on Elementary School Students’ Test Experience

Abstract: The use of digital media in education can bring great benefits and its use in schooling is steadily increasing. Administrating paper- versus computer-based as well as fixed-item versus adaptive tests could create differences in test experience, which can threaten the comparability of test results. This study investigated how the pen-and-paper, computer-based, and computer-adaptive test formats of a standardized reading comprehension test affect test anxiety and motivation among German fourth-grade students. A within-class randomized field trial with 387 fourth graders (aged: 9–10 years; 46.3% female) was conducted. Repeated-measures analysis of covariance (ANCOVA) revealed no differences in state test anxiety between the test formats when controlling for trait test anxiety and pre-test state anxiety, but state reading motivation was initially higher when reading on a screen, controlling for trait reading motivation. However, this difference diminishes over the course of the test. Implications for using digital media in elementary school test situations are discussed.

Lithium-Ion Battery State-of-Charge Estimation Using Electrochemical Model with Sensitive Parameters Adjustment

State-of-charge (SOC) estimation of lithium-ion (Li-ion) batteries with good accuracy is of critical importance for battery management systems. For the model-based methods, the electrochemical model has been widely used due to its accuracy and ability to describe the internal behaviors of the battery. However, the uncertainty of parameters and the lack of correction from voltage also induce errors during long-time calculation. This paper proposes a particle filter (PF) based method to estimate Li-ion batteries’ SOC using electrochemical model, with sensitive parameter identification achieved using the particle swarm optimization (PSO) algorithm. First, a single particle model with electrolyte dynamics (SPME) is used in this work to reduce the computational burden of the battery electrochemical model, whose sensitive parameters are selected through the elementary effect test. Then, the representative sensitive parameters, which are difficult to measure directly, are adjusted by PSO for a high efficiency. Finally, a model-based SOC estimation framework is constructed with PF to achieve accurate Li-ion battery SOC. Compared with extended Kalman filter and equivalent circuit model, the proposed method shows high accuracy under three different driving cycles.

A new anisotropic bending model for nonlinear shells: Comparison with existing models and isogeometric finite element implementation

A new nonlinear hyperelastic bending model for shells formulated directly in surface form is presented, and compared to four existing prominent bending models. Through an essential set of elementary nonlinear bending test cases, the membrane and bending stresses of each model are examined analytically. Only the proposed bending model passes all the test cases, while the other bending models either fail or only pass the test cases for small deformations. The proposed new bending model can handle large deformations and initially curved surfaces. It is based on the principal curvatures and their directions in the initial configuration, and it thus can have different bending moduli along those directions. These characteristics make it flexible in modeling a given material, while it does not suffer from the pathologies of existing bending models. Further, the bending models are compared computationally through four classical benchmark examples and one contact example. As the underlying shell theory is based on Kirchhoff–Love kinematics, isogeometric NURBS shape functions are used to discretize the shell surface. The linearization and efficient finite element implementation of the proposed new model are also provided.

Measurement of the Electron Magnetic Moment.

The electron magnetic moment, -μ/μ_{B}=g/2=1.001 159 652 180 59 (13) [0.13ppt], is determined 2.2 times more accurately than the value that stood for fourteen years. The most precisely determined property of an elementary particle tests the most precise prediction of the standard model (SM) to 1 part in 10^{12}. The test would improve an order of magnitude if the uncertainty from discrepant measurements of the fine structure constant α is eliminated since the SM prediction is a function of α. The new measurement and SM theory together predict α^{-1}=137.035 999 166 (15) [0.11ppb] with an uncertainty 10 times smaller than the current disagreement between measured α values.

Mean Reversion Lessens Mean Blur: Evidence from the S&P Composite Index

This study makes use of a very long time series of the S&P Composite Index, checking once more that the rates of return benefit from aggregational normality. It performs unit root tests as well as elementary statistical tests that take advantage of normality. It finds that mean blur is not consistent with the hypothesis of random walk with constant parameters, because the means of the annual real rates of linear return can be estimated as usual. It gives further evidence that the rates of return on the S&P Composite Index are mean-reverting.

ПРИСТРІЙ ДЛЯ ВИЗНАЧЕННЯ ТЕХНІЧНОГО СТАНУ ЦИФРОВИХ ТЕЗЩО ВИКОРИСТОВУЄ ПАРАМЕТРИ ЕНЕРГОДИНАМІЧНОГО ПРОЦЕСУ

The article examines the structural and functional diagrams of the device for diagnosing existing and prospective typical digital replacement elements, which contain microprocessor-based on large integrated circuits and are part of the radio-electronic equipment of the Armed Forces of Ukraine. The principle of operation of the device is based on the use as diagnostic information of initial reactions (IR) of object of diagnosis and parameters of the energy-dynamic process. The use of two power supply voltages and the step-by-step construction of the test sequence (TS) makes it possible to make a decision about the operational efficiency of the object of diagnosis with reliability no lower than specified for an acceptable time. Decision-making about the technical condition of a typical replacement element and localization of defects is carried out with the help of a personal computer based on the theory of fuzzy logic. The computer is the core that provides the analysis of the available and received diagnostic information, the formation of test sequences (TS) and decision-making about the technical condition of the object of diagnosis. It allows you to quickly process a large amount of diagnostic information, carry out its analysis, storage and replenishment due to the knowledge of experts and the accumulation of statistics. This makes it possible to exclude some elementary test effects, the need for which is eliminated based on the results of the obtained data, as well as to reduce the number of sets in the TS, which leads to a reduction in diagnosis time. Step-by-step execution of commands and current analysis of the situation allows not only to carry out diagnostics up to the first faulty element, but also makes it possible to conduct a further search for faulty elements. The advantage of the proposed device is the possibility of increasing the reliability of diagnosis without increasing its duration.