Fluctuating paths of least time, Schrödinger equation, van der Waals torque and Casimir effect mechanism

The use of an infinity of fluctuating paths of least time that are compatible with the quantum mechanics indeterminacy provides a new interpretation in geometrical optic of the interference pattern of Young’s double slit experiment, which suggests that the wave behavior of matter and radiation is dictated by the space-time geodesics. Moreover, the association of a wave function to each path of least time as a probability amplitude together with an uncertainty for momentum and position allows to derive the Schrödinger’s equation starting from the geodesic’s characteristics. A new insight is obtained regarding the van der Waals torque as well as Casimir attraction/repulsion mechanism.

Geometrical optic learning difficulties for Moroccan students during secondary/university transition

<p><span>To remedy the difficulties encountered by Moroccan students in geometrical optics during the transition from secondary to higher education and for an efficient education system, we propose this study to investigate the causes of these difficulties as well as their impact on the quality of the secondary/university transition, and come up with a remediation device to overcome them. For this survey, we adopted a mixed method to collect both qualitative and quantitative data. The research tools used are semi-directive interviews with thirty high school and university teachers; questionnaires and exercises were administered to 120 of first year university students. The results of this study revealed the persistence of difficulties in geometrical optics and particularly in geometric construction whose origins are attributed to the misrepresentations and low prerequisites among students as well as a break in the curriculum and teaching methods during the transition from secondary to higher education.</span></p>

Density Operator Approach to Turbulent Flows in Plasma and Atmospheric Fluids

We formulate a statistical wave-mechanical approach to describe dissipation and instabilities in two-dimensional turbulent flows of magnetized plasmas and atmospheric fluids, such as drift and Rossby waves. This is made possible by the existence of Hilbert space, associated with the electric potential of plasma or stream function of atmospheric fluid. We therefore regard such turbulent flows as macroscopic wave-mechanical phenomena, driven by the non-Hermitian Hamiltonian operator we derive, whose anti-Hermitian component is attributed to an effect of the environment. Introducing a wave-mechanical density operator for the statistical ensembles of waves, we formulate master equations and define observables: such as the enstrophy and energy of both the waves and zonal flow as statistical averages. We establish that our open system can generally follow two types of time evolution, depending on whether the environment hinders or assists the system’s stability and integrity. We also consider a phase-space formulation of the theory, including the geometrical-optic limit and beyond, and study the conservation laws of physical observables. It is thus shown that the approach predicts various mechanisms of energy and enstrophy exchange between drift waves and zonal flow, which were hitherto overlooked in models based on wave kinetic equations.

Site Prediction Model for the over Rooftop Path in a Suburban Environment at Millimeter Wave

This paper proposes the site-specific pathloss model for a small town in a suburban environment at millimeter wave. Also, the site general characteristics are provided in the entire measurement area of the small town. The proposed pathloss model is based on the moving measurement campaign according to the distance between a transmitter and a receiver in the candidate millimeter wave band or future five-generation service. In addition, the probability characteristics of pathloss such as the cumulative density function are shown to estimate the spreading characteristics of the wideband signal with a five-hundred-MHz bandwidth. Measurement was performed for the small town in a suburban covered with low-rise commercial restaurants or houses. Transmitting signals propagate through the over rooftop of low-rise houses of average ten meters height. Their multipath signals may be arrived at a receiving station located at the below roof of the house by reflection, diffraction, and scattered mechanism. A current propagation model for the over rooftop is based on generic or geometrical optic equations in a fully non-line-of-sight environment. But, non-line-of-sight cases in a realistic suburban environment include partly the open space between houses. Therefore, the definition of the propagation model of this sight-specific case is very important so clearly as to show the difference for the over rooftop according to the different displacements of houses in a non-line-of-sight environment. Finally, we suggest the improved propagation model of pathloss that can reflect various environments in a small town.

Pengembangan tes kemampuan berpikir kritis pada materi Optik Geometri untuk mahasiswa Fisika

Penelitian ini merupakan jenis penelitian & pengembangan yang dilakukan dengan tujuan untuk mengembangkan tes kemampuan berpikir kritis. Penelitian ini menggunakan model ADDIE dengan urutan tahapan penganalisisan, perencanaan, pengembangan, pengimplementasian, dan pengevaluasian, tetapi pada penelitian ini hanya dilakukan sampai tahap pengimplementasian. Tes yang dikembangkan dalam penelitian ini terdiri dari lima belas butir soal uraian. Validasi terhadap butir soal tes dilakukan dua kali, yaitu validasi isi dan validasi empiris. Hasil validasi isi menunjukkan bahwa nilai rata-rata butir soal tes sebesar 3,394 berkategori baik, sedangkan hasil validasi empiris menunjukkan bahwa ada sebelas soal berkategori valid dan empat soal berkategori tidak valid. Sebelas soal yang berkategori valid memiliki nilai koefisien reliabilitas Cronbach Alpha sebesar 0,67. Hasil implementasi tes menunjukkan hasil bahwa nilai rata-rata kemampuan berpikir kritis mahasiswa sebesar 27,20 dari 100,00 dengan nilai tertinggi 71,05 dan nilai terendah 2,63. Hal ini menunjukkan bahwa kemampuan berpikir kritis mahasiswa masih kurang.Kata kunci: tes kemampuan bepikir kritis, kemampuan berpikir kritis DEVELOPING CRITICAL THINKING SKILLS TEST IN GEOMETRICAL OPTIC FOR PHYSICS STUDENTAbstractThe kind of this study is the research and development that aims to develop critical thinking skills test. This study uses ADDIE model that has five steps: analyze, design, develop, implement, and evaluate, but in this study only done until the implementing step. This test consists of fifteen items essay test. Validation of this test performed twice, content validation and empirical validation. Content validation shows that this test have good categorized with average score 3,394, whereas empirical validation shows that there are eleven items that have valid categorized and four items that have invalid categorized. The valid items have reliabity coefficient Alpha Cronbach 0,67. The result of implementing step shows that students have average of critical thinking skill score 27,20 from 100,00 with the higest score 71,05 and the lowest score 2,63. This result shows that students’ critical thinking skills are still lacks.Keywords: critical thinking skills test, critical thinking skills

PENILAIAN PEMAHAMAN REPRESENTASI GRAFIK MATERI OPTIKA GEOMETRI MENGGUNAKAN TES DIAGNOSTIK

Abstrak: Tujuan penelitian adalah mengembangkan dan menerapkan tes diagnostik pilihan ganda tiga tingkat untuk mengukur pemahaman representasi grafik mahasiswa terkait esensi inkuiri sains dan materi optika geometri. Penelitian menggunakan metode campuran melibatkan 83 mahasiswa calon guru fisika di satu LPTK Sumatera Utara. Instrumen tes diagnostik terlebih dahulu didesain kemudian disempurnakan selama proses, direvisi, dan digunakan untuk mendeteksi dan menilai pemahaman representasi grafik mahasiswa calon guru fisika. Instrumen tes telah dikembangkan untuk dapat mendiagnosis dan memperbaiki kesalahan-kesalahan yang dilakukan calon guru fisika terkait dengan keterampilan mengonstruk grafik, menemukan kesulitan-kesulitan dalam membaca dan menginterpretasi grafik. Analisis data dilakukan secara kualitatif dan kuantitatif. Hasil studi menunjukkan pembacaan grafik dan keterampilan menginterpretasi grafik calon guru fisika masih belum memadai dan juga kemahiran dalam menganalisis grafik bergantung pada jenis grafik dan level atau tipe pertanyaan yang dikembangkan. Kata Kunci: representasi grafik, optik geometri, diagnostik tes ASSESSING OF UNDERSTANDING GRAPHICAL REPRESENTATION CONTENT GEOMETRICAL OPTIC USING DIAGNOSTIC TEST Abstract: The purpose of this study is to develop and apply three tier multiple choice diagnostic test to measure student’s understanding of graphical representation about essential features of inquiry and content geometrical optic. The study was conducted using mixed methods and carried out with 83 prephysics teachers at a University of Teachers Education in North Sumatera. The diagnostic instrument was designed and then progressively refined, revised, and implemented to detect and assess student’s understanding of graphical representation. Test instrument was developed to diagnose and correct the mistakes made by pre-service physics teachers about construction graphic skills, difficulties in the reading and interpretation graphical representation. The results of this study showed that graph reading and interpretation skills of pre service teachers were inadequate and also their graphing analysis varies depending on the type of graph and level type of question was developed. Keywords: graphical representation, geometrical optic, diagnostic test

Transformation of Rice’s small perturbation solution for rough surface scattering into the high frequency reciprocal physical and geometric optics solutions

A step by step transformation of the low frequency small height and slope perturbation solution into the high frequency reciprocal and dual, physical and geometrical optic solutions is presented. The familiar Kirchhoff approximations for the fields impressed by the incident plane wave upon the rough surfaces results in nonreciprocal solutions. It is shown that the surface element scattering coefficients based on the Kirchhoff approximations agree with the corresponding reciprocal physical optics solutions only at the stationary phase, specular points on the rough surfaces. While the Kirchhoff approximations and physical optics approximations are based on the characterization of the surface fields by Fresnel reflection coefficients, the corresponding surface element scatter coefficient derived for the small perturbation solution and the full wave solutions are based on the imposition of boundary conditions for the tangential components of the electric and magnetic fields. A flow graph schematically depicting the relationships between these solutions for the scattered fields is also presented.

Synchrotron x-ray μ-tomography to model the thermal radiative properties of an opaque ceramic coating at T = 1000 K

Synchrotron x-ray μ-tomography has been used to reconstruct the three-dimensional view of a rough surface extracted from a heterogeneous ceramic coating composed of Pr2NiO4+δ. Radiographs with a resolution of 0.7 μm have been recorded at T = 300, 600, and 900 K. The analysis of surface geometry makes use of the geometrical optic approximation up to T = 900 K possible. Subsequently, a large number of rays (105) are impinged onto the numerical surface, as revealed by x-ray tomography, to reproduce the normal emissivity of the coating. This normal emissivity was obtained beforehand by infrared emittance spectroscopy at T = 1000 K. Comparison of the two approaches suggests that the optical contribution of the coating micropores can be integrated into the ray tracing code. The effective medium approximation is used for this purpose. Finally, the applicability of this hybrid approach is discussed.

WAVE TRANSMISSION IN DISPERSIVE MEDIA

The aim of this paper is to study the reflection-transmission of geometrical optic rays described by semi-linear symmetric hyperbolic systems such as the Maxwell–Lorentz equations with the anharmonic model of polarisation. The framework is both that of Donnat and Williams since we consider dispersive media and profiles with hyperbolic (imaginary) phases and elliptic phases (complex with non-null real part). We first give hypothesis close to the Maxwell equation. Then we introduce a decomposition for both profile into boundary (tangential) and normal part and we solve the so-called "microscopic" equation of the small scales for each boundary frequency. Then we show that the non-linearities generate harmonics which interact at the boundary and generate new resonant profiles with harmonic tangential frequency. Lastly we make a WKB expansion at any order and give a precise description of the correctors.