The Physics Laboratory Works – Individualized Computer Simulations

The physics laboratory-works creating and operating computer simulations experience is described. A significant amount of laboratory works can be classified as a “black box”. The studied physical phenomenon is hidden from direct observation, the control is carried out by means of electrical measuring devices. It is difficult to distinguish physical reality from its imitation when performing such work, so the virtualization of this one does not require realistic images. The schematic representation of the laboratory installation greatly simplifies the process of creating a simulator. A unique set of installation parameters is formed for each student performing laboratory work on the simulator, which contributes to the independence of the student's work. These parameters are stored in Google Sheets. Their transfer to the laboratory work’s html-template is carried out in encrypted form through the Google Apps Script service. Virtual laboratory work is implemented as a cross-platform web application.

FEM ANALYSIS OF ENERGY LOSS DUE TO WAVE PROPAGATION FOR MICRO-PARTICLE IMPACTING SUBSTRATE WITH HIGH VELOCITIES

The impact between particles and material surface is a micro-scaled physical phenomenon found in various technological processes and in the study of the mechanical properties of materials. Design of materials with desired properties is a challenging issue for most industries. And especially in aviation one of the most important factors is mass. Recently with the innovations in 3D printing technologies, the importance of this phenomenon has increased. Numerical simulation of multi-particle systems is based on considering binary interactions; therefore, a simplified but as much accurate as possible particle interaction model is required for simulations. Particular cases of axisymmetric particle to substrate contact is modelled at select impact velocities and using different layer thicknesses. When modelling the particle impact at high contact velocity, a substrate thickness dependent change in the restitution coefficient was observed. This change happens is due to elastic waves and is important both to coating and 3D printing technologies when building layers of different properties materials.

Ovarian Biomechanics: From Health to Disease

Biomechanics is a physical phenomenon which mainly related with deformation and movement of life forms. As a mechanical signal, it participates in the growth and development of many tissues and organs, including ovary. Mechanical signals not only participate in multiple processes in the ovary but also play a critical role in ovarian growth and normal physiological functions. Additionally, the involvement of mechanical signals has been found in ovarian cancer and other ovarian diseases, prompting us to focus on the roles of mechanical signals in the process of ovarian health to disease. This review mainly discusses the effects and signal transduction of biomechanics (including elastic force, shear force, compressive stress and tensile stress) in ovarian development as a regulatory signal, as well as in the pathological process of normal ovarian diseases and cancer. This review also aims to provide new research ideas for the further research and treatment of ovarian-related diseases.

Numerical simulation of mold filling of semi-solid slurry based on viscosity theory

The mold filling of semi-solid slurry involves intricate theory and physical phenomenon. The influence of inner gate shape and filling speed on free surface and liquid-solid distribution is investigated by adopting finite element numerical simulation. The effect of viscosity is considered in the modelling. The results show that the inner gate shape affects the free surface. The filling speed of 3 m/s is favorable for the uniform distribution of solid-liquid phases. It has important guiding significance for the optimization of semi-solid forming process and molding design.

Development of laboratory devices for real-time measurement of object 3D position using stereo cameras

Measuring the 3D position at any time of a given object in real-time automatically and well documented to understand a physical phenomenon is essential. Exploring a stereo camera in developing 3D images is very intriguing since a 3D image perception generated by a stereo image may be reprojected back to generate a 3D object position at a specific time. This research aimed to develop a device and measure the 3D object position in real-time using a stereo camera. The device was constructed from a stereo camera, tripod, and a mini-PC. Calibration was carried out for position measurement in X, Y, and Z directions based on the disparity in the two images. Then, a simple 3D position measurement was carried out based on the calibration results. Also, whether the measurement was in real-time was justified. By applying template matching and triangulation algorithms on those two images, the object position in the 3D coordinate was calculated and recorded automatically. The disparity resolution characteristic of the stereo camera was obtained varied from 132 pixels to 58 pixels for an object distance to the camera from 30 cm to 70 cm. This setup could measure the 3D object position in real-time with an average delay time of less than 50 ms, using a notebook and a mini-PC. The 3D position measurement can be performed in real-time along with automatic documentation. Upon the stereo camera specifications used in this experiment, the maximum accuracy of the measurement in X, Y, and Z directions are ΔX = 0.6 cm, ΔY = 0.2 cm, and ΔZ = 0.8 cm at the measurement range of 30 cm–60 cm. This research is expected to provide new insights in the development of laboratory tools for learning physics, especially mechanics in schools and colleges.

The expression E = h × f is misleading because it implies the distribution of a photon quantum over 299 792 458 m, while the expression E = (h × c)/λ enables us to explain the particle-wave duality

The two equations E = h × f and E = (h × c)/λ for the quantum of energy of electromagnetic radiation provide the same result but describe electromagnetic radiation very differently. E = (h × c)/λ describes the quantum of energy of electromagnetic radiation to be located already in one wavelength and therefore like a particle. E = h × f describes the quantum of energy distributed over 299 792 458 m and therefore like a wave. To obtain h × f for the quantum of energy, we have to refer the quantum of energy to 299 792 458 m. Only then we obtain from E = (h × c)/(299 792 458 m), as the distance of 299 792 458 m of the velocity c is cancelling out now, E = h × 1/s = h × Hz, which is the precondition to obtain the correct value for the quantum of energy by multiplying Planck’s constant h by the frequency f. This already indicates the necessity of today's physics to have to speak of a particle-wave duality. It turns out that electromagnetic radiation consists of the first wavelength that carries the quantum of energy and behaves like a particle, which today is called “photon,” and a few following wavelengths that do not carry a further quantum of energy and behave like a wave, which today is called “electromagnetic wave.” By this knowledge, the particle-wave duality vanishes, and we obtain one single physical phenomenon, which I call “photon-wave.” The strange behavior of quantum objects at a single slit, at double-slits, and at beam splitters can now be understood in a causal way. “God does not play dice!” Einstein was right.

Ductile fracture modeling of metallic materials: a short review

Since the end of the last century a lot of research on ductile damaging and fracture process has been carried out. The interest and the attention on the topic are due to several aspects. The margin to reduce the costs of production or maintenance can be still improved by a better knowledge of the ductile failure, leading to the necessity to overcome traditional approaches. New materials or technologies introduced in the industrial market require new strategies and approaches to model the metal behavior. In particular, the increase of the computational power together with the use of finite elements (FE), extended finite elements (X-FE), discrete elements (DE) methods need the formulation of constitutive models capable of describing accurately the physical phenomenon of the damaging process. Therefore, the recent development of novel constitutive models and damage criteria. This work offers an overview on the current state of the art in non-linear deformation and damaging process reviewing the main constitutive models and their numerical applications.

Modulation Instability of Hydro-Elastic Waves Blown by a Wind with a Uniform Vertical Profile

An interesting physical phenomenon was recently observed when a fresh-water basin is covered by a thin ice film that has properties similar to the property of a rubber membrane. Surface waves can be generated under the action of wind on the air–water interface that contains an ice film. The modulation property of hydro-elastic waves (HEWs) in deep water covered by thin ice film blown by the wind with a uniform vertical profile is studied here in terms of the airflow velocity versus wavenumber. The modulation instability of HEWs is studied through the analysis of coefficients of the nonlinear Schrödinger (NLS) equation with the help of the Lighthill criterion. The NLS equation is derived using the multiple scale method in the presence of airflow. It is demonstrated that the potentially unstable hydro-elastic waves with negative energy appear for relatively small wind speeds, whereas the Kelvin–Helmholtz instability arises when the wind speed becomes fairly strong. Estimates of parameters of modulated waves for the typical conditions are given.

Novel soliton solutions of four sets of generalized (2+1)-dimensional Boussinesq–Kadomtsev–Petviashvili-like equations

In this paper, we examined four different forms of generalized (2+1)-dimensional Boussinesq–Kadomtsev–Petviashvili (B-KP)-like equations. In this connection, an accurate computational method based on the Riccati equation called sub-equation method and its Bäcklund transformation is employed. Using this method, numerous exact solutions that do not exist in the literature have been obtained in the form of trigonometric, hyperbolic, and rational. These solutions are of considerable importance in applied sciences, coastal, and ocean engineering, where the B–KP-like equations modeled for some significant physical phenomenon. The graph of the bright and dark solitons is presented in order to demonstrate the influence of different physical parameters on the solutions. All of the findings prove the stability, effectiveness, and accuracy of the proposed method.

CFD STUDY OF SHIP-TO-BANK INTERACTION

Ship-to-bank interaction is a complex physical phenomenon that involves not only in the asymmetric pressure field near banks or channels but also shallow water effect. Traditionally many experimental studies were carried out in this field. As numerical method is getting popular, there were various computational approaches as well. In this study, flow around a container ship in confined water is investigated with the open source CFD (Computational Fluid Dynamics) toolbox, OpenFOAM. Computations with several bank arrangements and different settings are performed. The OpenFOAM results are also compared to experiment results for validation.