Main Physical Principles Research Articles

Large, grid-connected solar photovoltaic power plants renewable energy

As an essential part of renewable energy, the solar photovoltaic technic grows rapidly with two main types: off-grid and grid-connected systems. This paper focuses on grid-connected solar photovoltaic power plants and introduces the main physical principles of solar photovoltaics. Typical components of solar photovoltaic power plants are also presented, along with their functions. The extraordinary environmental impact and the relatively low and decreasing cost of grid-connected solar photovoltaics reflect its excellent development potential. Compared with other energy, grid-connected solar photovoltaics provides an alternative to conventional fossil fuel generation. With the improvement of silicon purification technology and the working efficiency of solar batteries, the scale of grid-connected solar photovoltaics power plants will be further expanded.

Domestic Solar Heating: Historical Development, System Description,Social Aspects, and Future Prospects

With the advancing technology, there are many well-developed domestic solar systems with two main categories: activeheating systems and passive heating systems. This paper focuses on a functional heating system which includes solarwater and air heating systems. The main physical principles are solar thermal energy and heat transfer, implementedon solar collectors and heat exchangers. As for the environmental aspect, domestic solar heating systems can reducegreenhouse emissions, alleviating global warming. Moreover, with the increasing demand for renewable energy due tothe rising awareness of environmental protection, the marketing size of solar energy has become larger. Solar heatingsystems have been a fast-growing technology in many countries over the last decade. Compared with other energy, theprice of solar energy is considered the cheapest, which can help consumers save around $5,000 with a payback time of 5years. Therefore, the solar heating market will expand in the future because of carbon emission reduction and increasingefficiency.

Process virtualization for X-ray images obtaining in industrial radiography during nuclear power plant NDT specialists training

The research aims to highlight the analysis of the virtualization prerequisites in terms of the non-destructive testing training. The peculiarities of radiation control (RC), which significantly affect the organization of practical classes and the profitability of personnel training, are given. The main requirements for specialists in the course of practical training are listed. Methods of processing and visualizing information about the structure of dense three-dimensional bodies are considered and a simplified task-specified alternative is proposed. The results of the research underline the principle of image construction and processing through the use of digital twins of testing samples. This allows the user to get an image that is similar to shooting results of real metal samples in terms of training purposes. In order to deliver a more effective methodology, the main physical principles are taken into account for digital models of radiographs and optical density of films.

Compact Modeling Technology for the Simulation of Integrated Circuits Based on Graphene Field-Effect Transistors.

The progress made toward the definition of a modular compact modeling technology for graphene field-effect transistors (GFETs) that enables the electrical analysis of arbitrary GFET-based integrated circuits is reported. A set of primary models embracing the main physical principles defines the ideal GFET response under DC, transient (time domain), AC (frequency domain), and noise (frequency domain) analysis. Another set of secondary models accounts for the GFET non-idealities, such as extrinsic-, short-channel-, trapping/detrapping-, self-heating-, and non-quasi static-effects, which can have a significant impact under static and/or dynamic operation. At both device and circuit levels, significant consistency is demonstrated between the simulation output and experimental data for relevant operating conditions. Additionally, a perspective of the challenges during the scale up of the GFET modeling technology toward higher technology readiness levels while drawing a collaborative scenario among fabrication technology groups, modeling groups, and circuit designers, is provided.

Исследования процессов выделения газов из жидких сред в судовых сепарационных установках и аппаратах

Object and purpose of research. This paper discusses plants and units for splitting homogeneous (multi-phase) fluids into homogenous phases for shipbuilding and other industrial applications. The purpose of this work is to determine efficiency of hardware and solutions of various versions through simulation of separation processes for aerated 3D flows by means of configurable dummies at the experimental rig. Materials and methods. Official scientific and technical publications about analytical and experimental studies on the processes taking place in separation plants and units. Methodology of fluid and gas mechanics, dimension theory methods, experimental methods. Main results. This paper discusses the state of the art in development and operation of de-aeration plants and units in shipbuilding and related industries, with classification of main physical principles of fluid degassing. Experimental studies were performed at hydraulic test rig with unified versions of reconfigurable dummy for a variety of typical solutions currently applied at marine and industrial separation plants and units for controllable splitting of multi-phase flows into separate phases. Experimental assessment has found structural imperfections demonstrating the low technical level of investigated objects. It also highlighted behavioral patterns of highly saturated multi-phase flows with physical parameters established as per the practice of operating the equipment as part of systems, i.e. in different conditions and different configurations of closed-loop circuits. The study yielded new knowledge about the interaction of multi-phase flows with structural parts of a number of separation units. Finally, the study highlighted current obstacles for the optimization of separation processes, as well as suggested promising ways to high-end designs of separation plants and units. Conclusion. The findings of this work enable an objective decision-making about the application of given separation unit type in given service conditions as part of various marine or industrial systems. Technical solutions suggested in it will be helpful insights for development of more advanced and competitive separation units that would replace the imported products. The test data obtained in this work could also be helpful for further development of design requirements to marine ballast systems with high-capacity pumps.

Laser-induced breakdown spectroscopy in heritage science

Abstract Laser-induced breakdown spectroscopy (LIBS) is a versatile analytical technique that can be used to probe the elemental composition of materials in diverse types of heritage samples, objects or monuments. The main physical principles underlying LIBS are presented along with analytical figures of merit and technical details concerning instrumentation. In practice, LIBS analysis does not require any sample preparation and the technique is nearly non-invasive, offering close to microscopic spatial resolution and the possibility for depth profile analysis. These features are, at present, available in a number of compact or transportable instruments that offer versatility and enable the use of LIBS for the analysis of a broad variety of objects/samples at diverse locations and this can be highly valuable at several stages of archaeological investigations and conservation campaigns. Representative examples are presented indicating how LIBS has been used to obtain compositional information for materials in the context of archaeological science, art history and conservation.

The Coriolis mass flow meter as a volume meter for the custody transfer in liquid hydrocarbons logistics

In recent years, the Coriolis mass flow meters (CMF), devices based on the Coriolis effect over a vibrating pipe, have developed better metrological performance and they are now a reasonable alternative for the custody transfer measurements. Nowadays, many custody transfer operations require measurement of the net volume (volume measured at a certain reference temperature) and, therefore, it is not feasible to use the CMF as a mass flow meter. However, the actual CMF can be used as net volume meters because they have special equipment to measure density and temperature, and a flow computer. In this work, firstly a mathematical simplification of the physical model is proposed for the CMF. We part from the dimensional analysis of the flow-phase relationship produced by the Coriolis force, the main physical principle behind these devices. A simplified formula is obtained and it permits identifying the magnitudes of influence of the CMF as a mass meter. Secondly, its metrological properties are characterized. For such purpose, a 4” straight tube commercial meter has been calibrated in volume, in the 50 to 165 m3/h range against a standard container and a bidirectional prover, employing gas oil and kerosene (JET-A1). These calibrations have turned out to be compatible with the ones performed by the manufacturer in mass and using water. Then it is verified that the CMF fulfills the requisites of the legal metrology: maximum error allowed, linearity and repeatability. Skewness is observed in the relative error (expressed in %) of the CMF and it has been researched to be due to systematic effects related to constructive parameters of the meter. Lineal correlation is verified between relative error and temperature, and between relative error and flow rate, with negative slopes of −0.03% °C−1 and −0.001% h/m3 respectively.

Suppressing the thermal decomposition of forest fuel using the different water spraying schemes

This article presents the main findings of the experimental research into the fire suppression by continuous spraying of water over the combustion zone and by pulsed liquid aerosol delivery according to two schemes. The test samples con-tained either birch leaves only or mixed of (leaves, twigs, and needles). We monitored the temperature in the fuel bed and used thermocouple readings to determine the conditions and characteristics of suppressing the combustion and thermal decomposition of the material. Using optical methods and high speed recording, we obtained the parameters of sprayed liquid-flow as well as the processes involved in the interaction between liquid aerosol and the decomposing forest fuel. The experimental study helped us establish how much time and quenching liquid is sufficient to suppress the forest fuel combustion. Furthermore, we determined the influence of the forest fuel volume on the conditions and characteristics of the processes under study. Finally, we identified the main physical principles of the thermal decomposition of forest fuel when using the proposed approaches to spraying water into the combustion zone. The research findings enable the optimization of aerial firefighting in terms of wildfire containment and suppression.

Plasmonic Photodetectors

Plasmonic photodetectors are attracting the attention of the photonics community. Plasmonics is attractive because metallic structures have the ability to confine light by coupling an electromagnetic wave to charged carrier oscillations at the surface of the metal. The wavelength of such oscillations can be much smaller than the corresponding light wavelength in vacuum. This enables the light-matter interaction on a deep subwavelength scale, which in turn allows for more compact and potentially higher speed devices. In this review, we discuss different types of photodetectors and ways in which plasmonics can be applied to them. We elucidate several plasmonic photodetector concepts/schemes and discuss the main physical principles behind their operation. Finally, we reflect on the characteristics of an “ideal” photodetector and propose a device that might be the perfect plasmonic detector.

Controlled moiré effect in multiview three-dimensional displays: image quality and image generation

Approaches to control the moire effect are discussed. To improve the image quality, especially in the autostereoscopic three-dimensional displays, the minimization of the moire effect is considered, including the minimization by angle, by period, by distance, etc. Also, less known nontraditional but effective approaches, such as spectral trajectories, statistical treatment, convolution-based minimization, and the amplitude of the moire patterns, are at issue. On the other hand, the maximum moire can be useful in displays. A proposed “2.5-D” display represents a new type of displays, the displays based on the moire effect as on the main physical principle. As of today, binary black-and-white images are displayed, but this is not a principal limit and color imaging is also possible. A positive usage of the moire effect to show images instead of its removal may be considered as an approach in displaying.

From Micro- to Satellite Gravity: Understanding the Earth

The main physical principle of gravity method application is the difference in densities between the various geological, environmental, archaeological and other targets and host media. Gravity is one of the oldest geophysical methods and it is widely applied for knowledge of subsurface and deep Earth’s domains. The present review displays multiscale examples of gravity field examination: from very detailed (delineation of karst terranes and archaeological targets) to regional investigations (development of 3D physical-geological models and satellite data examination of giant regions). Geographically the examined areas include the South Caucasus, the Dead Sea region, the Eastern Mediterranean and the Arabian-African region. Diverse methodologies of the gravity data processing, qualitative and quantitative interpretation, and results of 3D gravity field modeling are shown. It is demonstrated that integration of gravity field analysis with other geophysical methods (magnetic, paleomagnetic, thermal, seismic, etc.) significantly increases accuracy and reliability of developed physical-geological models. The further ways of evaluation of gravity data analysis are considered.

Main principles of passive devices based on graphene and carbon films in microwave—THz frequency range

The ability of thin conductive films, including graphene, pyrolytic carbon (PyC), graphitic PyC (GrPyC), graphene with graphitic islands (GrI), glassy carbon (GC), and sandwich structures made of all these materials separated by polymer slabs to absorb electromagnetic radiation in microwave-THz frequency range, is discussed. The main physical principles making a basis for high absorption ability of these heterostructures are explained both in the language of electromagnetic theory and using representation of equivalent electrical circuits. The idea of using carbonaceous thin films as the main working elements of passive radiofrequency (RF) devices, such as shields, filters, polarizers, collimators, is proposed theoretically and proved experimentally. The important advantage of PyC, GrI, GrPyC, and GC is that, in contrast to graphene, they either can be easily deposited onto a dielectric substrate or are strong enough to allow their transfer from the catalytic substrate without a shuttle polymer layer. This opens a new avenue toward the development of a scalable protocol for cost-efficient production of ultralight electromagnetic shields that can be transferred to commercial applications. A robust design via finite-element method and design of experiment for RF devices based on carbon/graphene films and sandwiches is also discussed in the context of virtual prototyping.

Demonstration of the operation principles of intermediate band solar cells at room temperature

In this work we report, for the first time at room temperature, experimental results that prove, simultaneously in the same device, the two main physical principles involved in the operation of intermediate band solar cells: (1) the production of sub-bandgap photocurrent by two optical transitions through the intermediate band; (2) the generation of an output voltage which is not limited by the photon energy absorption threshold. These principles, which had always required cryogenic temperatures to be evidenced all together, are now demonstrated at room temperature on an intermediate band solar cell based on InAs quantum dots with Al0.3Ga0.7As barriers.

NUMERICAL STUDY OF THE INFLUENCE OF GEOMETRIC PARAMETERS ON THE AVALIABLE POWER IN A SOLAR CHIMNEY

In the presented work, it is made a numerical study about the main physical principle of a solar chimney (SCPP – Solar Chimney Power Plant) and the influence of some geometric parameters on the available power in the SCPP. The main objectives are to test the applicability of the studied numerical model in future studies of SCPP geometric optimization and to test the action of the collector inlet height (H1) and the chimney outlet diameter (D2) on the available power of the device. For that it is considered an incompressible, turbulent, steady flow with mixed convective heat transfer in a two-dimensional and axisymmetric domain, similar to the one found in a solar chimney. The conservation equations of mass, momentum and energy are numerically solved using the finite volume method, more specifically with the FLUENT software. The classical turbulence modeling (RANS) was used for the turbulence approach with standard model k – ε. The other geometric parameters: collector radius (R) and the inlet and outlet of the turbine section, R1 and R2, are also constant. The verification results indicated a good agreement with those presented in the literature, even using a simplified domain. It was also observed that the H1 parameter is almost insensitive in the solar chimney performance, whereas the D2 variable presented great influence in the available power. The best performance was attained for an intermediate value of D2, D2 = 0.44 m. For this value, the available power was almost 72% and 19% higher from those obtained in the inferior and superior extremes of the studied D2 variable, D2 = 0.22 m and 0.88 m, respectively. It was also observed that there is a very good possibility of optimization of the chimney geometry in future studies.

Semi-analytical response of acoustic logging measurements in frequency domain

This work proposes a semi-analytical method for simulation of the acoustic response of multipole eccentered sources in a fluid-filled borehole. Assuming a geometry that is invariant with respect to the azimuthal and vertical directions, the solution in frequency domain is expressed in terms of a Fourier series and a Fourier integral. The proposed semi-analytical method builds upon the idea of separating singularities from the smooth part of the integrand when performing the inverse Fourier transform. The singular part is treated analytically using existing inversion formulae, while the regular part is treated with a FFT technique. As a result, a simple and effective method that can be used for simulating and understanding the main physical principles occurring in borehole-eccentered sonic measurements is obtained. Numerical results verify the proposed method and illustrate its advantages.

Numerical Approach of the Main Physical Operational Principle of Several Wave Energy Converters: Oscillating Water Column, Overtopping and Submerged Plate

In this work it is numerically studied the wave flow inside a tank and the main operational physical principle of three different wave energy converters (WEC): oscillating water column (OWC), overtopping and submerged plate. The wave energy converters are evaluated in laboratory and real scales. For all studied cases the conservation equations of mass, momentum and one equation for the transport of volumetric fraction are solved with the finite volume method (FVM). To tackle with water-air mixture, the multiphase model Volume of Fluid (VOF) is used. Several results showed the accuracy of the numerical approach for estimation of the physical phenomenon of wave flow inside tanks, as well as, its interaction with the studied devices. For the cases with geometrical optimization, Constructal Design is employed for geometrical evaluation of the devices. Results presented several theoretical recommendations about the influence of geometrical parameters (such as ratios between heights and lengths of OWC chamber and ramp of overtopping device and the distance from the plate to the seabed of wave tank) over the available power take off (PTO) in the OWC and submerged plate devices and over the amount of water stored in the reservoir of the overtopping device. Results showed the importance of geometric shapes over the devices performance. Moreover, it is evaluated the influence of several wave parameters (such as wave period and relative depths) over the fluid dynamic performance of the devices and geometrical parameters of the devices. It is noticed the non-occurrence of universal optimal shapes.

Stellar oscillations - II - The non-adiabatic case

A leap forward has been performed due to the space-borne missions, MOST, CoRoT and Kepler. They provided a wealth of observational data, and more precisely oscillation spectra, which have been (and are still) exploited to infer the internal structure of stars. While an adiabatic approach is often sufficient to get information on the stellar equilibrium structures it is not sufficient to get a full understanding of the physics of the oscillation. Indeed, it does not permit one to answer some fundamental questions about the oscillations, such as: What are the physical mechanisms responsible for the pulsations inside stars? What determines the amplitudes? To what extent the adiabatic approximation is valid? All these questions can only be addressed by considering the energy exchanges between the oscillations and the surrounding medium. This lecture therefore aims at considering the energetical aspects of stellar pulsations with particular emphasis on the driving and damping mechanisms. To this end, the full non-adiabatic equations are introduced and thoroughly discussed. Two types of pulsation are distinguished, namely the self-excited oscillations that result from an instability and the solar-like oscillations that result from a balance between driving and damping by turbulent convection. For each type, the main physical principles are presented and illustrated using recent observations obtained with the ultra-high precision photometry space-borne missions (MOST, CoRoT and Kepler). Finally, we consider in detail the physics of scaling relations, which relates the seismic global indices with the global stellar parameters and gave birth to the development of statistical (or ensemble) asteroseismology. Indeed, several of these relations rely on the same cause: the physics of non-adiabatic oscillations.

Theory and detection scheme of seismic EM signals transferred into the atmosphere from the oceanic and continental lithosphere

Due to the compound structure of the medium and large portions of energy transferred, a seismic excitation in the oceanic or continental lithosphere disturbs all types of geophysical fields. To investigate the problem of electromagnetic (EM) disturbances in the atmosphere from the seismically activated lithosphere, we have formulated two mathematical models of interaction of fields of different physical nature resulting in arising of the low-frequency (from 0.1 to 10Hz by amplitude of a few hundreds of pT) EM signals in the atmosphere. First we have considered the EM field generation in the moving oceanic lithosphere and then in the moving continental one. For both cases, the main physical principles and geological data were applied for formulation of the model and characteristics of the computed signals of different nature agree with measurements of other authors. On the basis of the 2D model of the seismo-hydro-EM-temperature interaction in the lithosphere–Ocean–atmosphere domain, a block-scheme of a multisensory vertically distributed (from a seafloor up to the ionosphere) tsunami precursors’ detection system is described. On the basis of the 3D model of the seismo-EM interaction in a lithosphere–atmosphere domain, we explain why Prof. Kopytenko (Inst. IZMIRAN of Russian Acad. Sci.) and co-authors were able to estimate location of the future seismic epicenter area from their magnetic field measurements in the atmosphere near the earth’s surface.

A Novel Bar-Shaped Magnetic Shielding for Magnetoresistive Sensors in Current Measurement on Printed Circuit Boards

This paper presents the study of a novel bar-shaped magnetic shielding for magnetoresistive (MR) sensors in current measurement on printed circuit boards (PCB). The main physical principles of the shielding effect were studied by using the analytical model of magnetic flux concentration. Finite element analysis (FEA) simulations were used to simulate the shielding effects with changing geometrical parameters of the bar-shaped magnetic shielding. The dependences of the shielding effect on the parameters of length, width and thickness were analyzed. It shows that these parameters are critical for designing magnetic shielding. This new concept of magnetic shielding for MR sensors in current measurement on PCB was experimentally tested and verified in a laboratory setup. The experimental results verify the feasibility and effect of this novel magnetic shielding for MR sensors.

Magnetic flux concentration at micrometer scale

This paper presents the study of magnetic flux concentration phenomenon of magnetic flux concentrators (MFCs) at the micrometer scale. The main physical principles of magnetic flux concentration were studied by using analytical calculations and finite element method (FEM) simulations. The dependences of achievable maximum magnetic gain on the three critical parameters were analyzed. It shows that material, aspect ratio, and shape are three critical parameters for designing MFCs. Three typical MFCs were designed for magnetoresistive (MR) sensors in applications. The magnetic gain and linear working range of the MFCs were studied and compared. By using the same high-permeability magnetic material (nickel–iron alloy, μr ≈ 104−105), the MFCs of different geometries perform differently in magnetic amplification. The T-shaped concentrator shows higher magnetic amplification with magnetic gain G = 56 but comparatively narrower linear working range of 1.6 mTesla. The bar-shaped concentrator occupies smaller space and provides 62.5% wider linear working range (2.6 mTesla) than the T-shaped concentrator but at the expense of 32.1% smaller magnetic gain (G = 38). In the respect of magnetic gain, the triangle-shaped concentrator (G = 51) is comparable with the T-shaped concentrator. It provides a 42.3% wider linear working range (3.7 mTesla) than the bar-shaped concentrator.