Subjects -> PHYSICS (Total: 857 journals)
    - ELECTRICITY AND MAGNETISM (10 journals)
    - MECHANICS (22 journals)
    - NUCLEAR PHYSICS (53 journals)
    - OPTICS (92 journals)
    - PHYSICS (625 journals)
    - SOUND (25 journals)
    - THERMODYNAMICS (30 journals)

PHYSICS (625 journals)            First | 1 2 3 4 | Last

Showing 201 - 400 of 741 Journals sorted alphabetically
International Journal of Astronomy and Astrophysics     Open Access   (Followers: 36)
International Journal of Biological, Physical and Chemical Studies     Open Access  
International Journal of Computational Materials Science and Surface Engineering     Hybrid Journal   (Followers: 7)
International Journal of Damage Mechanics     Hybrid Journal   (Followers: 5)
International Journal of Engineering and Applied Physics     Open Access  
International Journal of Fatigue     Hybrid Journal   (Followers: 41)
International Journal of Fracture     Hybrid Journal   (Followers: 14)
International Journal of Geometric Methods in Modern Physics     Hybrid Journal   (Followers: 2)
International Journal of Geophysics     Open Access   (Followers: 5)
International Journal of Heat and Fluid Flow     Hybrid Journal   (Followers: 41)
International Journal of Low Radiation     Hybrid Journal  
International Journal of Low-Carbon Technologies     Open Access   (Followers: 1)
International Journal of Mass Spectrometry     Hybrid Journal   (Followers: 17)
International Journal of Material Forming     Hybrid Journal   (Followers: 1)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 2)
International Journal of Mechanical Sciences     Hybrid Journal   (Followers: 14)
International Journal of Mechanics and Materials in Design     Hybrid Journal   (Followers: 7)
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology     Open Access   (Followers: 11)
International Journal of Microstructure and Materials Properties     Hybrid Journal   (Followers: 7)
International Journal of Microwave Science and Technology     Open Access   (Followers: 12)
International Journal of Modeling, Simulation, and Scientific Computing     Hybrid Journal   (Followers: 3)
International Journal of Modern Physics A     Hybrid Journal   (Followers: 15)
International Journal of Modern Physics B     Hybrid Journal   (Followers: 12)
International Journal of Modern Physics C     Hybrid Journal   (Followers: 14)
International Journal of Modern Physics D     Hybrid Journal   (Followers: 13)
International Journal of Modern Physics E     Hybrid Journal   (Followers: 13)
International Journal of Multiphysics     Open Access  
International Journal of Nanomanufacturing     Hybrid Journal  
International Journal of Nanoscience     Hybrid Journal  
International Journal of Nanotechnology     Hybrid Journal   (Followers: 9)
International Journal of Non-Linear Mechanics     Hybrid Journal   (Followers: 8)
International Journal of Nonlinear Dynamics and Control     Hybrid Journal   (Followers: 6)
International Journal of Physics     Open Access   (Followers: 10)
International Journal of PIXE     Hybrid Journal  
International Journal of Plasticity     Hybrid Journal   (Followers: 7)
International Journal of Quantum Information     Hybrid Journal   (Followers: 6)
International Journal of Self-Propagating High-Temperature Synthesis     Hybrid Journal  
International Journal of Solids and Structures     Hybrid Journal   (Followers: 14)
International Journal of Surface Science and Engineering     Hybrid Journal   (Followers: 6)
International Journal of Theoretical and Applied Multiscale Mechanics     Hybrid Journal   (Followers: 3)
International Journal of Theoretical and Mathematical Physics     Open Access   (Followers: 13)
International Journal of Theoretical Physics     Hybrid Journal   (Followers: 17)
International Journal of Thermal Sciences     Hybrid Journal   (Followers: 18)
International Journal on Smart Sensing and Intelligent Systems     Open Access  
International Letters of Chemistry, Physics and Astronomy     Open Access   (Followers: 8)
International Materials Reviews     Hybrid Journal   (Followers: 15)
Iranian Journal of Medical Physics     Open Access  
Iranian Journal of Science and Technology, Transactions A : Science     Hybrid Journal  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 4)
Izvestiya, Atmospheric and Oceanic Physics     Full-text available via subscription   (Followers: 1)
Izvestiya, Physics of the Solid Earth     Hybrid Journal   (Followers: 2)
Jambura Physics Journal     Open Access  
JETP Letters     Hybrid Journal   (Followers: 3)
Journal of Adhesion Science and Technology     Hybrid Journal   (Followers: 10)
Journal of Advanced Physics     Full-text available via subscription   (Followers: 13)
Journal of Advances in Physics     Open Access   (Followers: 13)
Journal of Applied Mathematics and Physics     Open Access   (Followers: 9)
Journal of Applied Mechanics and Technical Physics     Hybrid Journal   (Followers: 7)
Journal of Applied Physics     Hybrid Journal   (Followers: 69)
Journal of Applied Spectroscopy     Hybrid Journal   (Followers: 9)
Journal of Astrophysics     Open Access   (Followers: 33)
Journal of Astrophysics and Astronomy     Open Access   (Followers: 58)
Journal of Building Physics     Hybrid Journal   (Followers: 1)
Journal of Chromatographic Science     Hybrid Journal   (Followers: 15)
Journal of Complex Networks     Hybrid Journal   (Followers: 1)
Journal of Composite Materials     Hybrid Journal   (Followers: 243)
Journal of Computational and Theoretical Transport     Hybrid Journal   (Followers: 2)
Journal of Computational Methods in Physics     Open Access   (Followers: 8)
Journal of Computational Physics     Hybrid Journal   (Followers: 59)
Journal of Computational Physics : X     Open Access   (Followers: 1)
Journal of Contemporary Physics (Armenian Academy of Sciences)     Hybrid Journal   (Followers: 9)
Journal of Dynamic Systems, Measurement, and Control     Full-text available via subscription   (Followers: 14)
Journal of Elasticity     Hybrid Journal   (Followers: 7)
Journal of Electron Spectroscopy and Related Phenomena     Hybrid Journal   (Followers: 3)
Journal of Electronic Materials     Hybrid Journal   (Followers: 3)
Journal of Electronics Cooling and Thermal Control     Open Access   (Followers: 9)
Journal of Engineering Materials and Technology     Full-text available via subscription   (Followers: 17)
Journal of Engineering Physics and Thermophysics     Hybrid Journal   (Followers: 2)
Journal of Experimental and Theoretical Physics     Hybrid Journal   (Followers: 4)
Journal of Experimental Physics     Open Access   (Followers: 3)
Journal of Fire Sciences     Hybrid Journal   (Followers: 6)
Journal of Geometry and Physics     Full-text available via subscription   (Followers: 2)
Journal of Geophysical Research : Space Physics     Full-text available via subscription   (Followers: 136)
Journal of Gravity     Open Access   (Followers: 4)
Journal of High Energy Astrophysics     Full-text available via subscription   (Followers: 25)
Journal of High Energy Physics     Hybrid Journal   (Followers: 17)
Journal of High Energy Physics, Gravitation and Cosmology     Open Access   (Followers: 2)
Journal of Hydrogels     Full-text available via subscription  
Journal of Hyperspectral Remote Sensing     Open Access   (Followers: 23)
Journal of Imaging     Open Access   (Followers: 3)
Journal of Information Display     Open Access   (Followers: 1)
Journal of Intelligent Material Systems and Structures     Hybrid Journal   (Followers: 8)
Journal of Lightwave Technology     Hybrid Journal   (Followers: 14)
Journal of Low Frequency Noise, Vibration and Active Control     Open Access   (Followers: 8)
Journal of Luminescence     Hybrid Journal   (Followers: 2)
Journal of Materials Engineering and Performance     Hybrid Journal   (Followers: 22)
Journal of Materials Physics and Chemistry     Open Access   (Followers: 7)
Journal of Materials Science     Hybrid Journal   (Followers: 25)
Journal of Materials Science : Materials in Electronics     Hybrid Journal   (Followers: 2)
Journal of Materials Science : Materials in Medicine     Hybrid Journal   (Followers: 1)
Journal of Mathematical Fluid Mechanics     Hybrid Journal   (Followers: 10)
Journal of Mathematical Physics     Hybrid Journal   (Followers: 25)
Journal of Medical Imaging and Health Informatics     Full-text available via subscription  
Journal of Medical Ultrasonics     Hybrid Journal   (Followers: 2)
Journal of Micro/Nanolithography MEMS and MOEMS     Hybrid Journal   (Followers: 24)
Journal of Molecular Spectroscopy     Hybrid Journal   (Followers: 6)
Journal of Motor Behavior     Hybrid Journal   (Followers: 8)
Journal of Multiscale Modeling     Hybrid Journal   (Followers: 1)
Journal of Nepal Physical Society     Open Access  
Journal of Nondestructive Evaluation     Hybrid Journal   (Followers: 11)
Journal of Nonlinear Dynamics     Open Access   (Followers: 6)
Journal of Nonlinear Mathematical Physics     Hybrid Journal   (Followers: 2)
Journal of Nuclear Physics, Material Sciences, Radiation and Applications     Open Access   (Followers: 6)
Journal of Optics     Hybrid Journal   (Followers: 17)
Journal of Photonics for Energy     Hybrid Journal   (Followers: 2)
Journal of Physical and Chemical Reference Data     Hybrid Journal   (Followers: 4)
Journal of Physical Chemistry B     Hybrid Journal   (Followers: 48)
Journal of Physical Chemistry C     Hybrid Journal   (Followers: 36)
Journal of Physical Oceanography     Hybrid Journal   (Followers: 18, SJR: 2.461, CiteScore: 3)
Journal of Physical Organic Chemistry     Hybrid Journal   (Followers: 8)
Journal of Physics and Chemistry of Solids     Hybrid Journal   (Followers: 3)
Journal of Plasma Physics     Hybrid Journal   (Followers: 21)
Journal of Polymer Science Part B: Polymer Physics     Hybrid Journal   (Followers: 22)
Journal of Porous Materials     Hybrid Journal   (Followers: 4)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 1)
Journal of Quantitative Spectroscopy and Radiative Transfer     Hybrid Journal   (Followers: 3)
Journal of Reinforced Plastics and Composites     Hybrid Journal   (Followers: 30)
Journal of Rheology     Full-text available via subscription   (Followers: 7)
Journal of Sandwich Structures and Materials     Hybrid Journal   (Followers: 4)
Journal of Scientific Research     Open Access  
Journal of Sensors     Open Access   (Followers: 25)
Journal of Sol-Gel Science and Technology     Hybrid Journal  
Journal of Solid State Physics     Open Access   (Followers: 8)
Journal of Spectroscopy     Open Access   (Followers: 6)
Journal of Superconductivity and Novel Magnetism     Partially Free   (Followers: 1)
Journal of Synchrotron Radiation     Open Access   (Followers: 3)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 32)
Journal of the ICRU     Hybrid Journal  
Journal of the Korean Physical Society     Partially Free  
Journal of the Physical Society of Japan     Hybrid Journal   (Followers: 2)
Journal of Theoretical and Applied Physics     Open Access   (Followers: 9)
Journal of Tissue Engineering     Open Access   (Followers: 6)
Journal of Ultrasound in Medicine     Full-text available via subscription   (Followers: 11)
Journal of Vibration and Control     Hybrid Journal   (Followers: 42)
Journal of Visualization     Hybrid Journal   (Followers: 3)
Journal of Zhejiang University : Sceince A     Hybrid Journal  
JPSE (Journal of Physical Science and Engineering)     Open Access  
Jurnal Fisika     Open Access  
Jurnal Ilmiah Pendidikan Fisika Al-Biruni     Open Access  
Jurnal NEUTRINO     Open Access  
Jurnal Online of Physics     Open Access  
Jurnal Pendidikan Fisika Indonesia (Indonesian Journal of Physics Education)     Open Access  
Jurnal Penelitian Fisika dan Aplikasinya     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Karbala International Journal of Modern Science     Open Access  
Kasuari : Physics Education Journal     Open Access  
La Rivista del Nuovo Cimento     Hybrid Journal  
Lasers in Surgery and Medicine     Hybrid Journal   (Followers: 1)
Latvian Journal of Physics and Technical Sciences     Open Access  
Letters in High Energy Physics     Open Access  
Letters in Mathematical Physics     Hybrid Journal   (Followers: 4)
Light : Science & Applications     Open Access   (Followers: 3)
Living Reviews in Computational Astrophysics     Open Access   (Followers: 3)
Living Reviews in Relativity     Open Access  
Living Reviews in Solar Physics     Open Access   (Followers: 1)
Lubrication Science     Hybrid Journal   (Followers: 2)
Macalester Journal of Physics and Astronomy     Open Access   (Followers: 5)
Machining Science and Technology: An International Journal     Hybrid Journal   (Followers: 2)
Magnetic Resonance     Open Access  
Magnetic Resonance Letters     Open Access  
Magnetic Resonance Materials in Physics, Biology and Medicine     Hybrid Journal   (Followers: 3)
MAPAN     Hybrid Journal  
Mass Spectrometry Reviews     Hybrid Journal   (Followers: 31)
Matéria (Rio de Janeiro)     Open Access  
Materials and Design     Open Access   (Followers: 47)
Materials at High Temperatures     Full-text available via subscription   (Followers: 3)
Materials Chemistry and Physics     Full-text available via subscription   (Followers: 15)
Materials Research Bulletin     Hybrid Journal   (Followers: 25)
Materials Research Innovations     Hybrid Journal   (Followers: 1)
Materials Science     Hybrid Journal   (Followers: 7)
Materials Science and Engineering: A     Hybrid Journal   (Followers: 44)
Materials Science and Engineering: B     Hybrid Journal   (Followers: 22)
Materials Science and Engineering: R: Reports     Hybrid Journal   (Followers: 15)
Materials Science and Technology     Hybrid Journal   (Followers: 40)
Materials Today Physics     Hybrid Journal   (Followers: 1)
Matériaux & Techniques     Full-text available via subscription   (Followers: 2)
Mathematical Physics, Analysis and Geometry     Hybrid Journal   (Followers: 3)
Mathematics and Mechanics of Solids     Hybrid Journal   (Followers: 3)
Matter and Radiation at Extremes     Open Access   (Followers: 1)
Meccanica     Hybrid Journal   (Followers: 1)
Mechanics of Advanced Materials and Structures     Hybrid Journal   (Followers: 6)
Mechanics of Materials     Hybrid Journal   (Followers: 25)
Mechanics of Time-Dependent Materials     Hybrid Journal   (Followers: 2)
Mechanics Research Communications     Hybrid Journal   (Followers: 4)
Medical Physics     Hybrid Journal   (Followers: 17)
Micro and Nano Systems Letters     Open Access   (Followers: 6)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 11)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 9)
Modern Instrumentation     Open Access   (Followers: 57)
Modern Physics Letters A     Hybrid Journal   (Followers: 14)

  First | 1 2 3 4 | Last

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Latvian Journal of Physics and Technical Sciences
Journal Prestige (SJR): 0.226
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0868-8257 - ISSN (Online) 2255-8896
Published by Sciendo Homepage  [370 journals]
  • Study on Potential Role and Benefits of Liquified Natural Gas Import
           Terminal in Latvia

    • Abstract: Natural gas is relatively clean energy source, which emits less greenhouse gases (hereinafter – GHG), compared to other fossil fuels, such as hard and brown coal, and therefore it may be the most feasible resource to ensure smooth energy transition towards Europe’s climate neutrality by 2050. Traditional natural gas can be easily transported and used in liquefied (hereinafter – LNG) or compressed form. As for biomethane, in future it also can be used in liquefied (hereinafter – bioLNG) and compressed form, as well as transported by means of the current natural gas infrastructure. It can also significantly enhance regional and national energy security and independence, which has been challenging for the European Union (hereinafter – EU) over at least several decades.Issue on energy independence, security of supply, alternative natural gas sources has been in a hotspot of the Baltic energy policy makers as well. Now, considering Russia’s invasion in Ukraine, since late February 2022, a problem of the EU natural gas dependency on the Russian Federation has escalated again and with force never before experienced. The European natural gas prices also hit records, as the natural gas prices in the Netherlands Title Transfer Facility reached 345 euros per megawatt-hour (hereinafter – EUR/MWh) in March 2022.Therefore, LNG import terminal is the only viable option to reduce national dependency of the so-called pipe gas which in some cases, due to the insufficient interconnections, may be delivered from very limited number of sources. The European policy makers and relevant institutions are currently working towards radical EU natural gas supply diversification, where LNG deliveries coming from outside of Russia will certainly take a central stage.In case of Latvia, the potential benefits of the LNG terminal development in Skulte were evaluated in order to reduce energy independence of the Russian natural gas deliveries in the Baltic region and to introduce new ways and sources of the natural gas flows to the Baltics. LNG terminal in Skulte could ensure significant capital investment cost reduction comparing to other projects proposed for Latvia in different periods, due to already existing natural gas transmission infrastructure and the relative closeness to the Incukalns underground gas storage (hereinafter – UGS). Various aspects, such as technical, political and economic ones, were analysed to assure that Skulte LNG terminal would be a real asset not only to customers of Latvia, but also to those of the whole Baltic region, where in future it would be possible to use biomethane for efficient utilisation of existing and developing natural gas infrastructure.
      PubDate: Fri, 22 Apr 2022 00:00:00 GMT
       
  • Study on Mass and Linear Attenuation Coefficients of PMMA as Human
           Tissue-Equivalent Material

    • Abstract: To research the improvements of clinical imaging of human tissues, tissue-equivalent materials are one of the reasonable strategies for evaluating the impact of radiation dosages on human tissues. Hence, considering mass and linear attenuation coefficients is a promising method to foresee the appropriate tissue-identical material. In this examination, we utilise the built-up estimations of elemental compositions (mass portion of every component) of PMMA material by numerous analyses in literature. XCOM program was utilised to figure estimations of mass attenuation coefficients of PMMA for various photon energies (0.015–2.0) MeV. The outcomes reveal that the estimations of mass and linear attenuation coefficients are high as the energies begin to decrease and diminish gradually with an expansion in photon energies. Making a sensible coordinating between mass and linear attenuation coefficients of PMMA as human tissue-equivalent material with mass and linear attenuation coefficients of lung, brain, muscle and blood human tissues has demonstrated a phenomenal match.
      PubDate: Fri, 22 Apr 2022 00:00:00 GMT
       
  • Lattice Dynamics Calculations for MgZnO Solid Solutions

    • Abstract: In this study, Mg1-xZnxO solid solutions are studied by modelling lattice dynamics, using the methods of classical molecular dynamics. These time-efficient methods are of great interest since they allow using large crystallic structures, which reduce artificial defect periodicity. The main program used is General Utility Lattice Program (GULP). The Buckingham potential is used for modelling interatomic forces. The parameters for this potential are found for different effective ionic charges by using lattice parameters and vibrational frequencies obtained from ab initio calculations performed in the program CRYSTAL14. With these potentials, the dispersion relations and densities of states have been calculated for MgO, ZnO and Mg1-xZnxO. Calculations have been made for different Mg and Zn contents in the wurtzite and cubic phase solid solutions, respectively, using the supercell method and a large number of Brillouin zone sampling points.New interatomic potentials for interactions Mg-O, O-O, Zn-O have been obtained. These potential parameters have been verified and the phonon dispersion curves and DOS for MgO and ZnO utilising these potential parameters have been compared to other studies, both experimental and theoretical. By adding more Zn in the cubic phase (c-MgO) solution, no local vibrational modes are observed; however, there is a clear spectral widening and a noticeable change in the low frequency region (100–300 cm−1) of the DOS. Adding more Mg in wurtzite phase (w-ZnO) solution, on the other hand, results in local vibrational modes in the mid (350 cm−1) and high frequency (650 cm−1) regions.
      PubDate: Fri, 22 Apr 2022 00:00:00 GMT
       
  • Maximum Shannon Information Delivered in a Lecture

    • Abstract: The aim of our paper is to evaluate the maximum Shannon (syntactic) information carried through a video lecture. To achieve the aim, we have considered a natural lecture delivered by a lecturer as a signal transmitted over the physical communication channel consisting of a sound sub-channel and light sub-channel. Receivers are eyes and ears of listeners whose physical characteristics are taken into account. The physiological, neurological and cognitive aspects of the problem are neglected in calculations. The method has been developed to calculate the absolute maximum values of Shannon information characteristics of a natural lecture basing on the capacity formula of continuous communication channel and physical considerations taken into account for the first time, to our knowledge. Maximum Shannon information characteristics (entropies of sound and light frames, amounts of total acoustical and optical information, capacities of sound and light sub-channels, total amount of information and total capacity) of a natural lecture perceived by the audience have been calculated. These values are the upper bounds of a video lecture. The obtained results are discussed in the paper. After some modification, the proposed method can be practically applied for the optimization of both natural and video lectures because there is some correlation between syntactic and semantic information characteristics.
      PubDate: Fri, 22 Apr 2022 00:00:00 GMT
       
  • Application Possibilities of the Off-Grid HVAC System Operation Solution
           for Temporary Shelters in the Latvian Climate Conditions

    • Abstract: Temporary shelters are extensively used by emergency services (rescue, disaster relief, military response) and other end-users requiring temporary mobile power solutions for different purposes (event organization, vacation homes, summer camps, etc.). The Covid-19 pandemics resulted in an increase of motor homes worldwide sales.When temporary shelter connection to power grid is impossible, the off-grid liquid fossil fuel generator can be used for electricity generation. Since the liquid fuel supply is often limited, the stock of fuel requires storage that may pose an explosion risk. Quickly installable and energy-efficient ventilation / cooling system with heat recovery is essential to ensure adequate air hygiene and occupants’ comfort in temporary structure.This paper presents a mobile modular electric energy generating unit with photovoltaic (PV) panels for providing temporary shelters (tents) in Latvian climate conditions with heating, ventilation, and air conditioning (HVAC). All calculations were performed using the computer model developed with TRNSYS tool and based on real data from mobile modular energy unit for spring, summer and autumn 2020 and winter 2021. The results show that mobile modular energy unit can be successfully applied for off-grid HVAC system operation of temporary shelters in the Latvian climate conditions.
      PubDate: Fri, 22 Apr 2022 00:00:00 GMT
       
  • Identification of the Parameters of a Three-Phase Asynchronous Motor for
           Intelligent Monitoring Systems

    • Abstract: The study presents an algorithm and a mathematical model for evaluating the parameters of the equivalent circuit of an asynchronous electric motor for intelligent monitoring systems. To identify the parameters of electric motors, a gradient descent method is used to find the minimum of a positive function. The algorithm and mathematical model were tested not only theoretically, but also in laboratory experiments. The results obtained proved that the proposed algorithm was an efficient and accurate method for estimating parameters. Computer modelling and experimental research confirmed the possibility of using the algorithm and the device for identifying parameters in the construction of control systems for a variable frequency drive with three-phase asynchronous electric motors in practice.
      PubDate: Fri, 22 Apr 2022 00:00:00 GMT
       
  • The Least-Cost Optimization of PV-Station DC/AC Equipment Using Battery
           Energy Storage System

    • Abstract: The auction allocation of state support quotas for renewable generation implementation that will change the existing incentive for their development by providing “green” tariffs to producers is based on competitive selection of the power plant projects with the least cost of electricity generation. The competitive advantage of solar photovoltaic power plant (PV stations) projects can be done by deciding what kind of equipment can provide the minimum cost of electricity generation during the period of operation. In the article, there is improvement of non-linear mathematical least-cost optimization model of the structure of PV-station equipment using DC coupled battery energy storage system (BESS) to store the excess electricity of photovoltaic modules (PV modules), which is lost on inverters when they are overloaded during the hours of the highest intensity of solar radiation. The article presents the modelling results of overall operation of PV station with fixed power of PV modules, as well as determines optimal power of inverter equipment and battery capacity. The model calculations have shown that when the DC equipment costs of the PV station are reduced by almost 62 % and DC equipment costs of BESS are reduced by 86.7 % of the actual value in 2020 at the power of 10 MW PV modules, the optimal power of inverter equipment decreases from 7.08 to 6.29 MW, and the storage capacity increases from 0.22 to 2.51 MWh. The use of BESS allows accumulating the amount of electricity produced by PV modules, which is lost with limitation on inverters, while the cost of their joint electricity production is decreased by 0.42 %.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
       
  • Evaluation of Received Signal Power Level and Throughput Depending on
           Distance to Transmitter in Testbed for Automotive WLAN IEEE 802.11ac
           Communication Network

    • Abstract: WLAN IEEE 802.11ac is one of the wireless network technologies that can be used for ITS (Intelligent Transport Systems) needs, in particular for providing vehicle passengers with access to the data transmission network. To evaluate the performance of such automotive wireless access networks, it is necessary to perform experimental measurements. By conducting the throughput measurements in WLAN-based automotive communications testbed, it has been observed that the throughput of the communication channel decreases and the received signal becomes weaker as the vehicle moves away from the wireless access point. The aim of the research is to verify theoretically whether there is a correlation between the received signal power level and the throughput of the communication channel depending on the distance to the transmitter. To calculate the received signal power depending on the distance to the transmitter, a log-normal signal propagation model can be used, which takes into account random signal fluctuations that are described by the Nakagami distribution. Further, based on the obtained results, Shannon’s theorem can be used to calculate the maximum theoretical throughput of the communication channel. The analysis of the obtained results shows that a correlation exists between the received signal power level and the throughput of the communication channel depending on the distance to the transmitter. The performed theoretical calculations justify the experimentally obtained results.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
       
  • Morphology Influence on Wettability and Wetting Dynamics of ZnO
           Nanostructure Arrays

    • Abstract: Changes in nanostructure morphology and size may result in very different surface wettability. In this research, the impact of different morphological parameters on the wetting dynamics of ZnO nanostructured layers is studied. Six different morphologies are chosen to determine the specific wetting processes of ZnO nanostructures: nanoneedles, small diameter rods, large diameter rods, nanotubes, nanoplates, and plain thin films. Wetting dynamics is investigated using conventional sessile drop technique and a novel approach based on electrochemical impedance spectroscopy. The results show that the surface of nanostructured ZnO thin films exhibits both hydrophilic and hydrophobic wetting behaviour, depending on nanostructure form, size, and orientation. ZnO nanostructure arrays are a promising platform for electrochemical and optical sensing in aqueous solutions. The full and effective use of the sensor working surface can be ensured only under the condition of complete wetting of the nanostructured layer. Therefore, it is important to take into account the peculiarities of the wetting process of a specific morphology of nanostructures.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
       
  • Solar Microwave Emission Associated with Coronal Mass Ejections (CME)

    • Abstract: The connection between Coronal Mass Ejections (CME) and radio burst has been discovered especially at lower frequencies (< 2 GHz). The aim of the study is to investigate possible connection between CMEs and variability of radio brightenings at 37 GHz (8 mm) within the time frame of four days. The millimetre radio observations have been made on RT-14 radio telescope at Metsähovi Radio Observatory of Aalto University, Finland. In addition, 11.2 GHz (2.7 cm) total solar flux information is included in the analysis. The radio observations were made between March 2011 and September 2017, totally including 24 events. The results demonstrate that in most of the cases the radio brightening intensity achieves its maximum before CME occurs. Time of 11.2 GHz intensity appearance matches with time of CME appearance with difference of two to three hours. However, in most cases a maximum of 11.2 GHz intensity appears before CMEs. The study investigates a possibility of predicting CME appearance based on milli- and centimetre radio observations. The study also proposes a scenario connection between CMEs and solar microwave events.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
       
  • The Relation Between Photoconductivity Threshold and Open-Circuit Voltage
           in Organic Solar Cells

    • Abstract: Most of the solar cell parameters (short-circuit current, fill factor, power conversion efficiency) can only be determined by creating and measuring the solar cell. However, there is an empirical relation that links energy level values of the materials in the active layer to an open-circuit voltage (Uoc) of the solar cell. Due to a variety of possible methods used to determine energy level values and the dispersion of obtained results, this estimate is not always correct. Even if correct energy level values are obtained for separate materials, energy level shift takes place at the interfaces when two materials are mixed. That is why a simple and reliable experimental method for Uoc estimation is required. Usually, photoconductivity is used to obtain the energy gap between molecule ionization energy and electron affinity of a single material. When two materials are mixed, direct charge transfer from donor to acceptor molecule can be observed. The threshold energy (ECT) shows the real difference between donor molecule ionization energy and acceptor molecule electron affinity. This difference should correspond to the Uoc. The present study makes the comparison between the open-circuit voltage estimated from material energy level values, the obtained ECT values for various donor:acceptor systems, and the real Uoc obtained from solar cell measurements. Strong correlation between ECT and Uoc is obtained and the photoconductivity measurements can be used in the estimation of Uoc.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
       
  • Investigation of Power Efficiency Changes in DWDM Systems Replacing
           Erbium-Doped Amplifiers By Semiconductor Optical Amplifiers

    • Abstract: To evaluate potential utilization of semiconductor optical amplifiers (SOAs) as a wideband amplification alternative to erbium doped fibre amplifiers (EDFAs) in dense wavelength division multiplexed (DWDM) coherent systems, the authors discuss changes in power consumption levels required for a single bit transmission. The research evaluates the power efficiency parameter for WDM transmission systems using both amplification schemes – EDFAs that utilise standard C-band and SOAs assuming 75 nm amplification spectral band. The power efficiency levels have been estimated for five transmission spans with maximal distance of 640 km. The standard 50 GHz channel spacing has been chosen for both system configurations to allocate 100 Gbps dual-polarization quadrature phase shift keying (DP-QPSK) optical signals. The simulation schemes are described along with the critical parameters, derived from the recent relevant studies that should be taken into account considering usage of SOAs as in-line amplifiers.
      PubDate: Wed, 02 Feb 2022 00:00:00 GMT
       
  • The Effect of the Range of a Modulating Phase Mask on the Retrieval of a
           Complex Object from Intensity Measurements

    • Abstract: In many fields of science, it is often impossible to preserve the information about the phase of the electromagnetic field, and only the information about the magnitude is available. This is known as the phase problem. Various algorithms have been proposed to recover the information about phase from intensity measurements. Nowadays, iterative algorithms of phase retrieval have become popular. Many of these algorithms are based on modulating the object under study with several masks and retrieving the missing information about the phase of an object by applying mathematical optimization methods. Several of these algorithms are able to retrieve not only the phase but also the magnitude of the object under study. In this study, we investigate the effect of the range of modulation of a mask on the accuracy of the retrieved magnitude and phase map. We conclude that there is a sharp boundary of the range of modulation separating the successfully retrieved magnitude and phase maps from those retrieved unsuccessfully. A decrease in the range of modulation affects the accuracy of the retrieved magnitude and phase map differently.
      PubDate: Tue, 07 Dec 2021 00:00:00 GMT
       
  • Three Stages of Composite Specimen Destruction in Static Failure

    • Abstract: The paper presents the results of standard specimen fracture made of anisotropic carbon fiber plastic with an epoxy matrix. Static stepwise loading of the specimen was carried out on an Instron 8801 testing machine to determine the characteristics of ductile fracture G1C in the first mode in accordance with ASTM D5528.During loading, the parameters of acoustic emission (AE) signals, such as AE impulse amplitudes and their energy were synchronously recorded. At the same time, the magnitude of the opening and the growth of the crack initiated by the artificial cut at the end of the specimen were recorded.According to the analysis of the acoustic emission signals, three zones with different G1C behaviour were identified: initial crack propagation, its stationary growth and accelerated fracture of the specimen. The zonal character of the change in the acoustic emission signals made it possible to determine the energy of the acoustic emission signals as diagnostic evidence for the onset of rapid destruction of the specimen.The amplitude of the AE-signals in the zones, however, remained constant. Online monitoring of changes in the energy of acoustic emission signals will prevent the onset of rapid destruction of an object in places of its deformations. The paper does not aim at defining G1C as usual. It presents the investigation of the fracture stages for a composite material using an acoustic emission method.
      PubDate: Tue, 07 Dec 2021 00:00:00 GMT
       
  • WO as Additive for Efficient Photocatalyst Binary System TiO/WO

    • Abstract: Two different methods of synthesis of TiO2/WO3 heterostructures were carried out with the aim to increase photocatalytic activity. In this study, anodic TiO2 nanotube films were synthesized by electrochemical anodization of titanium foil. WO3 particles were applied to anodic Ti/TiO2 samples in two different ways – by electrophoretic deposition (EPD) and insertion during the anodization process. Structural and photocatalytic properties were compared between pristine TiO2 and TiO2 with incorporated WO3 particles. Raman mapping was used to character-ise the uniformity of EPD WO3 coating and to determine the structural composition. The study showed that deposition of WO3 onto TiO2 nanotube layer lowered the band gap of the binary system compared to pristine TiO2 and WO3 influence on photo-electrochemical properties of titania. The addition of WO3 increased charge carrier dynamics but did not increase the measured photo-current response. As the WO3 undergoes a phase transition from monoclinic to orthorhombic at approximately 320 ℃ proper sequence WO3 deposition could be beneficial. It was observed that secondary heat treatment of WO3 lowers the photocurrent.
      PubDate: Tue, 07 Dec 2021 00:00:00 GMT
       
  • Methodology for Increasing the Competences of Housing Managers in Climate
           Change Issues

    • Abstract: In order to identify the necessary competences and develop the study course programme, within the framework of the EUKI (The European Climate Initiative; Die Europäische Klimaschutzinitiative) project “From Housing Manager to CLImate Manager”, research [1] has been conducted, describing the Latvian residential fund, analysing the principles and activities of multi-apartment residential buildings, as well as identifying and describing the parties involved in shaping the housing policy. Special attention is paid to energy efficiency issues for buildings – looking at Latvia’s potential for climate changes, analysing energy consumption in buildings in relation to energy efficiency requirements, as well as assessing the medium and long-term objectives of buildings in Latvia and the obstacles to achieving them.In order to clarify more precisely the necessary competences of housing managers for the successful implementation of the residential renovation process, a survey has been carried out for stakeholders in the project. Based on an analysis of the situation and the performed survey results, a methodology has been developed to increase the competences of housing managers in relation to the renovation of residential buildings in order to mitigate climate change.
      PubDate: Tue, 07 Dec 2021 00:00:00 GMT
       
  • Influence of “Productive” Impurities (Cd, Na, O) on the Properties of
           the CuZnSnS Absorber of Model Solar Cells

    • Abstract: The study focuses on the optical properties of the CZTS multicomponent semiconductor absorber with 3 % “production” impurities of Cd, Na, O within the framework of the density functional theory using the generalized gradient approximation and the SCAPS program, as well as investigates their influence on the performance and efficiency of CZTS-solar cells. The results showed that the introduction of Cd, Na, O impurities would lead to a decrease in the intensity of the absorption bands at 2.06 eV and 2.55 eV. The density of states CZTS: (Cd, Na, O) was determined from first principles, and it was revealed that impurities of Cd and O atoms would lead to a decrease in the band gap (to 0.9 eV and 0.79 eV), and an increase in Na impurity absorption (1.2 eV). It was also found that a decrease in the band gap led to a decrease in the open circuit voltage, and it was also shown that “industrial” impurities led to a decrease in the efficiency of energy conversion of solar cells to 2.34 %.
      PubDate: Tue, 07 Dec 2021 00:00:00 GMT
       
  • Investigation of the Flow-Based Fast Reroute Model with Implementation of
           a Multimedia Quality Protection Scheme

    • Abstract: In this paper, a tensor flow-based fast reroute model with multimedia quality protection is proposed. In the model, the conditions for implementing a multipath routing strategy and flow conservation are introduced taking into account possible packet loss at the network nodes and preventing overloading communication links both when using the primary and backup routes. At the same time, the novelty of the proposed solution is the formalization of the conditions of protection of the Quality of Experience level in terms of multimedia quality along the primary and backup routes. These conditions have been obtained during the tensor formalization of the network, which made it possible to calculate the quality of service indicators: packet loss probabilities, as well as the average end-to-end delay for audio and video flows transmitted in the multimedia session using the primary and backup routes, respectively. As a criterion for the optimality of the obtained solutions, a condition has been selected related to maximizing the overall performance of the infocommunication network. The results of the research of the proposed model confirm the adequacy of the numerical research results obtained for solving the problem of fast rerouting with link/node protection.
      PubDate: Tue, 07 Dec 2021 00:00:00 GMT
       
  • Forecasting Algorithm Based on Temperature Error Prediction Using Kalman
           Filter for Management System Development

    • Abstract: The study offers a new method of collection and processing of meteorological data from the meteorological service based on observations and correction of numerical weather forecast errors using a new prediction algorithm. This algorithm vastly increases the accuracy of the short-term forecast of outdoor air temperature, which is subject to uncertainty due to the stochastic nature of atmospheric processes. Processing of temperature data using Kalman filter provides the decrease in predicted temperature errors. The main setup methods of Kalman filter have been examined. The article also describes the implementation of accuracy improving algorithm of predicted temperature using Python.
      PubDate: Fri, 08 Oct 2021 00:00:00 GMT
       
  • Damage Detection of the Rod in the Crossflow Using Surrogate-Based
           Modelling

    • Abstract: An effective and accurate methodology is developed to create an inverse surrogate model for the mass reduction analysis of the rod in the rod bundle inserted in the crossflow. The performance of two surrogate modelling approaches has been evaluated. These models are the Response Surface Method and Legendre polynomial approximations. The relationship between dominant frequencies, support stiffness and rod mass derived from Computational Fluid Dynamics simulations is used as input data for approximations. The selection of sample points is implemented with a new type of orthogonal design. The results have shown that the proposed methodology can reliably replace the finite volume model and drastically reduce computational time.
      PubDate: Fri, 08 Oct 2021 00:00:00 GMT
       
 
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