bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward a general model for reflection recovery and single image enhancement
Authors: Chang Meng , Li Qi , He Zhuang , Feng Huajun , Xu Zhihai
Published: June 2020

Images often suffer from low visual quality due to poor imaging conditions such as low light or hazy weather. The haze imaging model is widely used in contrast enhancement in daylight condition with haze, while the retinex model is universal for low‐light conditions. Although their forms and applications are different, they can be unified into a more general form through the proposed observation. Based on this model, the authors can estimate the reflection of the scene more accurately in more complex imaging conditions. In this study, the authors propose a simple but effective method for estimating the reflection and enhancing the image contrast based on a general imaging model. To preserve the image details and control contrast, the authors introduce dark boundary and bright boundary to handle the high‐light and low‐light conditions, and a guided structure‐preserving optimization algorithm is proposed to estimate them. After obtaining the dark and bright boundaries, the reflection is calculated and the image is enhanced accordingly. Different from previous approaches, which were designed for specific applications, the proposed method can be used for more diverse imaging conditions. Experiments show that the proposed method can be applied to many poor imaging conditions and maintain good performance.
Retracted: Research on measurement and energy efficiency improvement of flat panel display based on industrial control
Authors: Cui Yuan , Yu Yang , Chen Zhuyang , Xue Bo
Published: June 2020

In view of the fact that on flat panel display industrial production line, the power consumption is very important and determined by their different driving modes and light‐emitting principles. Based on the industrial control systems, this paper analyses the power consumption of flat panel display, studies the main factors affecting its power consumption and analyses the main methods to improve light efficiency and reduce power consumption. This paper also discusses the focus issues in the current standard of flat panel display power measurement at home and abroad. According to the characteristics of different flat panel displays, this paper discusses the dual indexes of power consumption and efficiency in power measurement, and how to consider the influence of screen brightness and angle of view in the measurement.
Retracted: Improved artificial bee colony algorithm with opposition‐based learning
Authors: Cao Yongcun , Ji Saisai , Lu Yong
Published: June 2020

The artificial bee colony (ABC) algorithm is a biological‐inspired optimisation algorithm proposed by Karaboga. Since its solution search equation is good at exploration but poor at exploitation, the ABC algorithm converges slowly and is easy to fall into local optimum. Inspired by opposition‐based learning (OBL), the authors propose an improved ABC algorithm called opposition‐based learning ABC (OLABC). In OLABC, firstly, the population would be initialised using OBL. Secondly, to ensure the diversity of the population during the iterative process, the solution search equation is employed to bee phase would be improved. Generate the opposite solution when the fitness value of the newly generated solution is smaller than the current solution, and then apply the greedy selection strategy to update the solution. Thirdly, the adaptive weight strategy is used to dynamically adjust the weight, balancing the global exploration and local exploitation capabilities of the algorithm. Experiments on a set of benchmark functions show that OLABC has better convergence speed and optimisation precision than the compared algorithms.
Performance optimisation of the grid‐connected flyback inverter under improved hybrid conduction mode
Authors: Mohammadi Saleh , Izadfar Hamid Reza , Eskandarian Naser
Published: June 2020

In the unfolding‐type interleaved two‐switch flyback inverter (ILTFI) operating in discontinuous conduction mode (DCM), the hybrid control strategy combining the one‐phase DCM and the two‐phase DCM has a significant impact on improving the efficiency under all load conditions. In the situation where the marginal power of this control strategy is increased, the converter may enter CCM. Consequently, the converter cannot track the reference current and the output current quality is notably decreased. To tackle this issue, a novel hybrid control method is proposed which varies the switching frequency based on the output power. The proposed approach is immune to the loss analysis and power losses of the components. Hence, it is independent of components selection and their characteristics. In this case, the smooth transition between the one‐phase and the two‐phase operation modes is guaranteed without affecting the output power quality and the stability of the converter in DCM. The control complexity of the proposed scheme is low and the converter can be easily controlled in DCM. The performance of the flyback microinverter with the proposed hybrid control scheme is verified by the simulation and the experimental results together with the loss analysis.
Deep learning approach for wind speed forecasts at turbine locations in a wind farm
Authors: Kou Peng , Wang Chen , Liang Deliang , Cheng Song , Gao Lin
Published: June 2020

In a wind farm, individual turbines disturb the wind field by generating wakes, so wind speeds at various turbine locations are different. From the perspective of wind farm control, there is an interest in dynamic optimization of the power reference for each individual wind turbine, and the wind speed forecast at each turbine location is hence required. This paper develops a joint model of convolutional neural network (CNN) and the gated recurrent units (GRU) to forecast the wind speed at turbine locations. This model employs a two‐layer architecture. At the lower‐layer, the spatial features are automatically extracted by CNN. The extracted spatial features describe the spatial correlations among multiple wind turbines. At the upper‐layer, GRU learns the temporal correlations across the extracted spatial features. This joint model is trained in an integrated manner. A salient characteristic of this model is that it extracts high‐level spatial‐temporal features from wind data. These automatically learnt features capture the spatial‐temporal wind dynamics and interactions in a wind farm, thus being informative and appropriate for the forecasting at specific turbine locations. The simulation on actual data demonstrates the effectiveness of the presented model.
Optimising power system frequency stability using virtual inertia from inverter‐based renewable energy generation
Authors: Farmer Warren J. , Rix Arnold J.
Published: June 2020

The objective of this study is to optimise the use of virtual inertia given a virtual inertia budget and a network topology. Following a brief investigation into inertia distribution, it was observed that distributed inertia is more effective than centralised inertia for a large and sparse power system network. A subsection of the South African transmission network, the Western Transmission network, is expected to host large‐scale inverter‐based generation. The total power system inertia is in decline due to the large‐scale integration of inverter‐based renewable energy generation. In the literature, mitigation methods such as virtual inertia and ‘noise‐cancelling’ network topology design has been proposed to improve frequency stability. In this study, the Western Transmission network is modelled as a network of coupled oscillators. A state‐space model for the power system network is developed with virtual inertia as a feedback control loop. The ‐norm is used to design optimal feedback control through virtual inertia allocation/distribution, to increase power system frequency stability. The results show that the optimal distribution significantly improves system frequency stability by decreasing the rate of change of frequency and delaying the time to reach similar frequency nadir values.
Improved voltage control method of power system based on doubly fed wind farm considering power coupling under grid short‐circuit fault
Authors: Ouyang Jinxin , Pang Mingyu , Zheng Di , Yuan Yifeng , Diao Yanbo
Published: June 2020

The participation of wind farms in grid emergency control is considered necessary to ensure the safe and stable operation of power systems with high‐proportion wind generation. The grid voltage can be improved through the power control of doubly fed wind farm (DFWF) under grid faults. However, existing methods provide reactive power within the allowable power range (APR) under internal constraints of doubly fed wind turbine (DFWT). The precise control of DFWF is difficult to achieve, and its power controllability is underutilised because of the different operation status of DFWTs and the coupling between the APR and the grid voltage. Accordingly, an improved control method of DFWF is proposed to improve the voltage under grid fault. The power characteristics of DFWF are analysed. APR is described under internal constraints. The feasible power range (FPR) of DFWT under coupling is investigated. The connotations of FPR and APR are analysed, based on which a novel idea of active control of DFWF power is proposed. The maximum and optimal voltage operation points of DFWT under wind speed and rotor speed restrictions are calculated. The improved voltage control strategy is proposed. The simulation shows that the proposed method can significantly improve the voltage through the precise control of DFWF power.
Correlation function: biasing and fractal properties of the cosmic web
Authors: Einasto J. , Hütsi G. , Kuutma T. , Einasto M.
Published: June 2020

Aims. Our goal is to determine how the spatial correlation function of galaxies describes biasing and fractal properties of the cosmic web.

Methods. We calculated spatial correlation functions of galaxies, ξ(r), structure functions, g(r) = 1 + ξ(r), gradient functions, γ(r) = d log g(r)/d log r, and fractal dimension functions, D(r) = 3 + γ(r), using dark matter particles of the biased Λ cold dark matter (CDM) simulation, observed galaxies of the Sloan Digital Sky Survey (SDSS), and simulated galaxies of the Millennium and EAGLE simulations. We analysed how these functions describe fractal and biasing properties of the cosmic web.

Results. The correlation functions of the biased ΛCDM model samples at small distances (particle and galaxy separations), r ≤ 2.25 h−1 Mpc, describe the distribution of matter inside dark matter halos. In real and simulated galaxy samples, only the brightest galaxies in clusters are visible, and the transition from clusters to filaments occurs at a distance r ≈ 0.8−1.5 h−1 Mpc. At larger separations, the correlation functions describe the distribution of matter and galaxies in the whole cosmic web. The effective fractal dimension of the cosmic web is a continuous function of the distance (separation). Real and simulated galaxies of low luminosity, Mr ≥ −19, have almost identical correlation lengths and amplitudes, indicating that dwarf galaxies are satellites of brighter galaxies, and do not form a smooth population in voids.

Conclusions. The combination of several physical processes (e.g. the formation of halos along the caustics of particle trajectories and the phase synchronisation of density perturbations on various scales) transforms the initial random density field to the current highly non-random density field. Galaxy formation is suppressed in voids, which increases the amplitudes of correlation functions and power spectra of galaxies, and increases the large-scale bias parameter. The combined evidence leads to the large-scale bias parameter of L⋆ galaxies the value b⋆ = 1.85 ± 0.15. We find r0(L⋆) = 7.20 ± 0.19 for the correlation length of L⋆ galaxies.
The CARMENES search for exoplanets around M dwarfs
Authors: Fuhrmeister B. , Czesla S. , Hildebrandt L. , Nagel E. , Schmitt J. H. M. M. , Jeffers S. V. , Caballero J. A. , Hintz D. , Johnson E. N. , Schöfer P. , Zechmeister M. , Reiners A. , Ribas I. , Amado P. J. , Quirrenbach A. , Nortmann L. , Bauer F. F. , Béjar V. J. S. , Cortés-Contreras M. , Dreizler S. , Galadí-Enríquez D. , Hatzes A. P. , Kaminski A. , Kürster M. , Lafarga M. , Montes D.
Published: June 2020

The He I infrared (IR) triplet at 10 830 Å is known as an activity indicator in solar-type stars and has become a primary diagnostic in exoplanetary transmission spectroscopy. He I IR lines are a tracer of the stellar extreme-ultraviolet irradiation from the transition region and corona. We study the variability of the He I triplet lines in a spectral time series of 319 M dwarf stars that was obtained with the CARMENES high-resolution optical and near-infrared spectrograph at Calar Alto. We detect He I IR line variability in 18% of our sample stars, all of which show Hα in emission. Therefore, we find detectable He I variability in 78% of the sub-sample of stars with Hα emission. Detectable variability is strongly concentrated in the latest spectral sub-types, where the He I lines during quiescence are typically weak. The fraction of stars with detectable He I variation remains lower than 10% for stars earlier than M3.0 V, while it exceeds 30% for the later spectral sub-types. Flares are accompanied by particularly pronounced line variations, including strongly broadened lines with red and blue asymmetries. However, we also find evidence for enhanced He I absorption, which is potentially associated with increased high-energy irradiation levels at flare onset. Generally, He I and Hα line variations tend to be correlated, with Hα being the most sensitive indicator in terms of pseudo-equivalent width variation. This makes the He I triplet a favourable target for planetary transmission spectroscopy.
Coronavirus and Its Impact on Dental Fraternity
Authors: Prasad D Krishna , Prasad D Anupama , Parakh Mayank Kumar
Published: June 2020

The coronavirus disease-2019 (COVID-19) is a pandemic the world is currently facing head on. It is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). No current vaccine is available nor a curative treatment option is available at present, thus making it even more important to prevent the disease. Since dentists are in very close contact with their patients and there is aerosol production in various dental treatments, they are at a heightened risk of contracting the disease. To prevent the disease, strict hand and respiratory hygiene needs to be followed. Personal protective equipment should be used for any emergency procedures and thorough history must be taken of every patient. Digitalization of seminars and classes has been adopted by various dental institutions. With high infectivity of the virus, social distancing and stringent prevention protocols can help in controlling this severe global threat.
Atom interferometry with ultracold Mg atoms: frequency standard and quantum sensors
Authors: Taichenachev A V , Goncharov A N , Bonert A E , Baraulya V I , Tropnikov M A , Kuznetsov S A , Prudnikov O N , Bagayev S N
Published: June 2020

The results of theoretical and experimental studies aimed at the creation of matter wave interferometers with Mg atoms are presented. Atom-optical interferometers based on the Ramsey-Bordé scheme are of great interest for the development of optical frequency standards. Ultracold Mg atoms are promising for the development of an optical frequency standard with relative uncertainty and long-term frequency instability at a level of 10−17 − 10−18. A long-term frequency stability of 3·10−15 is obtained at an averaging time τ = 103 s while stabilizing the frequency of a ‘clock’ laser at 457 nm (1
S
0 → 3
P
1 transition) to narrow Ramsey-Bordé resonances of Mg atoms cooled and localized in a magneto-optical trap. The measured frequency stability is determined by the stability of the measurement system based on an optical frequency comb stabilized to the optical frequency of a Yb:YAG/I2 standard. We also present the results of theoretical studies aimed at the use of Mg atom interferometers based on Bragg diffraction for quantum sensing.
The influence of polarization of noble-gas atoms in strong laser field on high-order harmonic generation
Authors: Romanov A. A. , Silaev A. A. , Frolov M. V. , Vvedenskii N. V.
Published: June 2020

We study the ionization and high-order harmonic generation by argon atoms subjected into the intense laser pulse based on the numerical solution of the time-dependent Kohn-Sham equations. We demonstrate that atom polarization leads to significant screening of the external electric field and decrease in the atom ionization probability. At high leaser-pulse intensity, the suppression of depletion lead to enhancement of the HHG yield in comparison with the single-active electron approximation, which neglects the polarization effect.
Dynamical Mass Generation in Graphene by Bicircular Laser Fields
Authors: Suster M C , Derlikiewicz J , Kotur K M , Cajiao Vélez F , Krajewska K , Kamiński J Z
Published: June 2020

Electron-hole creation in single-layer intrinsic graphene interacting with bicircular laser fields is investigated. Due to the linear dispersion relation near the degeneracy points, the electron and hole dynamics are treated according to the Dirac theory, i.e., it is assumed that the charge carriers behave as ultrarelativistic massless fermions. Of special interest is their dynamical mass generation induced by a THz electromagnetic radiation. The harmonic response from graphene and electron currents induced by the bicircular laser field are also analyzed.
Control of Mid-IR Waveforms Generated During Gas Ionization by Two-Color Laser Pulses
Authors: Silaev A. A. , Romanov A. A. , Vvedenskii N. V.
Published: June 2020

The paper is devoted to further investigation of the generation of tunable mid-infrared radiation during gas ionization by two-color laser pulses. We demonstrate that control of generated mid-infrared frequency can be ensured with the use of linearly chirped laser pulse by changing the group delay between the laser-pulse components.
Characteristic quantities for nonequilibrium Bose systems
Authors: Yukalov V I , Novikov A N , Yukalova E P , Bagnato V S
Published: June 2020

The paper discusses what characteristic quantities could quantify nonequilibrium states of Bose systems. Among such quantities, the following are considered: effective temperature, Fresnel number, and Mach number. The suggested classification of nonequilibrium states is illustrated by studying a Bose-Einstein condensate in a shaken trap, where it is possible to distinguish eight different nonequilibrium states: weak nonequilibrium, vortex germs, vortex rings, vortex lines, deformed vortices, vortex turbulence, grain turbulence, and wave turbulence. Nonequilibrium states are created experimentally and modeled by solving the nonlinear Schrödinger equation.
Faraday waves and droplets in quasi-one-dimensional Bose gases
Authors: Tomio Lauro , Gammal A. , Abdullaev F.Kh , Kumar R. K.
Published: June 2020

Faraday waves (FW) are studied in mixtures of Bose gases by taking into account quantum fluctuations beyond the GP mean-field formalism with the Lee-Huang-Yang term, with both inter-and intra-species scattering lengths periodically varying in time. In this case, the effect of periodic modulations on the system is studied, with nonlinear resonances shown to be excited in the oscillation widths of quantum droplets. It was shown that the period of the Faraday patterns is quite sensitive to the estimated value obtained by the beyond mean-field contribution, which can be used to measure quantum fluctuations in the ground state of the quasi-one-dimensional mixture. Variational predictions are confirmed by full numerical simulations. We also add an analysis of quantum droplets and quantum fluctuation contributions when considering three-body interactions.
From optical lattices to quantum crystals
Authors: Yukalov I
Published: June 2020

Optical lattices can be loaded with atoms which can have strong interactions, such that the interaction of atoms at different lattice sites cannot be neglected. Moreover, the intersite interactions can be so strong that it can force the atoms to form a self-organized lattice, such that exists in crystals. With increasing intersite interactions, there can appear several lattice states, including conducting optical lattices, insulating optical lattices, delocalized quantum crystals, and localized quantum crystals.
Beam cleaning effects in multimode GRIN-fiber Raman lasers and amplifiers
Authors: Kuznetsov A.G. , Nemov I.N. , Wolf A.A. , Kablukov S.I. , Babin S.A. , Chen Yizhu , Yao Tianfu , Leng Jinyong , Zhou Pu
Published: June 2020

Raman conversion in multimode GRIN fibers is accompanied by sufficient improvement of the output beam quality in comparison with that for pump radiation, which offers opportunities to create amplifiers and lasers of new type based on directly 9xx-nm diode pumped passive GRIN fibers, which may operate at almost any wavelength in transmission window (0.95-2 micron) of silica fibers. Here we review experimental results and physical mechanisms leading to the beam quality improvement (beam cleaning) in multimode Raman lasers and amplifiers, including effects of Raman gain, fiber Bragg gratings and Rayleigh backscattering feedback in GRIN fibers.
High-energy bremsstrahlung on atoms in a laser field
Authors: Krachkov P. A. , Piazza A. Di , Milstein A. I.
Published: June 2020

The impact of a laser field on the process of photon radiation by an ultra-relativistic electron in an atomic field is investigated. The angular distribution and the spectrum of the radiated photon are derived. By means of the quasiclassical approximation, the obtained results are exact in the parameters of the laser field and the atomic field. It is shown that the impact of the laser field is significant even for fairly average values of the laser field parameters routinely achievable nowadays. Therefore, an experimental observation of the influence of the laser field on bremsstrahlung in the atomic field is a very feasible task.
The influence of material parameters on optical and electrical properties of indium-tin oxide (ITO) layer
Authors: Musztyfaga-Staszuk M , Starowicz Z , Panek P , Socha R , Gawlińska-Nęcek K
Published: June 2020

Indium tin oxide (ITO) layers of various thicknesses were deposited on silicon substrate using magnetron sputtering technique. The use of the layers is dedicated to solar cells produced on the basis of heterostructures at low range of temperatures up to 300 °C. The structure, surface composition and both, optical and electrical properties of the layers were investigated. Optical parameters were characterized by spectrophotometry and ellipsometry, atomic force microscopy (AFM), scanning electron microscopy (SEM) and four-pointed probe as well as X-ray diffraction (XRD). In order to measure the resistivity of the connection zone between electrode and deposit layer transmission line method (TLM) was used. The connection zone between electrode and ITO layer were manufactured in the temperature range of 150-250 °C. Electrodes were formed from silver conductive paste. The use of ITO layer allows optimization of optical parameters in relation to electrical properties of the layer and enables creation of contacts with low resistivity values in low-temperature metallization processes.
Investigation of photothermal effect in nanomaterials
Authors: Stępińska I , Kozłowski M , Diduszko R , Biernacki K , Wronka H , Czerwosz E
Published: June 2020

The thermal emission dependence on various nanostructural materials absorption of electromagnetic irradiation was investigated. Nanomaterials containing Au and Ag nanoparticles, and CuO nanorods have been studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy. These nanomaterials were synthesised by physical vapour deposition and by a thermal oxidation process. The preliminary results of a photothermal experiment for all these materials are presented. The temperature increase due to this effect was observed.
IDEs structures created in the physical vacuum deposition process on textile substrates
Authors: Korzeniewska E , Szczęsny A , Kasprowicz D
Published: June 2020

The article proposes a method for producing interdigitated electrodes structures on a flexible composite substrate in the physical vacuum deposition process. Ag and Au with a purity of 99.99% were used as deposited metals. The results of impedance measurement of created structures in the range up to 500 kHz are presented. Based on the results of computer simulation, an equivalent circuit for computer simulation of the structures has been proposed based on measurement result. It can be used in the design of sensors built based on IDEs in textronic systems. The very high agreement was obtained between impedance measurements and simulation results up to tens of kilohertz.
Comparison of trimethylgallium decomposition models for epitaxy growth analysis in MOVPE reactors
Authors: Niedzielski Przemyslaw
Published: June 2020

Numerical analysis of the trimethylgallium (TMGa) decomposition during epitaxy growth process was analysed. The main aim is to compare previously published trimethylgallium decomposition models. Hence, thermo-fluidic and species transport simulations of the MOVPE (metal-organic vapour phase epitaxy) reactor were performed. Study is focused on a simplified, but most crucial mechanism of epitaxy growth: chemical model of a TMGa decomposition. Analysis of species densities and pyrolysis speed for different approaches were beneficial to understand emerging phenomena during epitaxy growth and to choose most applicable method for future consideration. Analysis have been conducted with the aid of Ansys Fluent software. Numerical simulations depict extreme results, indicating that selecting correct model as a base for the growth process modelling is crucial.
Monte Carlo simulations of hole transport in 4H-SiC using DOS calculations
Authors: Kovalchuk Andrii , Wozny Janusz , Lisik Zbigniew , Podgorski Jacek , Ruta Lukasz , Kubiak Andrzej , Boiadzhian Armen
Published: June 2020

In this article we show results of 4H-SiC Monte Carlo simulation of hole transport based on numerically calculated density of states. As a result of these simulations the hole mobility for low electric field is obtained. To properly include scattering on ionized acceptor dopants the Brooks-Herring and Conwell-Weisskopf models are used.
Thermal Design of Microreactor Structural Elements for Water Quality Analyser
Authors: Matviykiv O , Klymkovych T , Farmaha I , Bokla N , Marikutsa U , Pytel K
Published: June 2020

The research object is a Lab-chip device for environmental water quality monitoring. The main objective of the actual work is to determine a set of functional, geometric and technological parameters of Lab-chip microreactor to provide optimal temperature field conditions for predefined chemical reaction protocols. Since Lab-chip operates with a microdose of liquids or reagents and temperature processes in fluid flows are highly inertial, the problem of setting, maintaining and ensuring fast transient of certain temperature values in different areas of Lab-chip microchannels is nontrivial. The main focus was pointed on precise heating of defined Lab-chip areas (reaction chambers) and strict compliance with the non-stationary thermal regime, required for chemical reaction protocols. Modelling and simulation were done in COMSOL Multiphysics tool. As a result of the conducted research, there was obtained a set of parameters that provides the required thermal regime of reaction microchamber for the physicochemical determination of selected hazardous species in environmental water samples.
Thermal investigation of power diodes in novel integrated disc type packages
Authors: Massa S , Raj E
Published: June 2020

Paper focusses on electro-thermal numerical investigation of a novel disc type package for power diodes integrated with microchannel cooling system. Although the new solution ensures much lower average temperature of an electronic element, it results in much higher temperature non-uniformity obtained within the silicon structure. The distribution can be improved with the aid of redesigned microchannel cooler. The maximum junction temperature reduction of more than 25 °C is possible.
Thermoelectric cooling and heating of human body temperature
Authors: Gould C A
Published: June 2020

The cooling and/or heating of human body temperature is of critical importance and interest in a myriad of applications, however, the use of thermoelectric cooling has made little impact in this area. Current solutions focus on the use of wearable materials that assist the natural temperature regulation of the human body, or the use of liquid cooling techniques reliant on refrigerant fluid or large quantities of dry ice, often used in astronaut spacesuits, worn by surgeons during long surgical procedures, firefighters, military personnel, and motor racing drivers. The motivation for this work is to investigate the feasibility of using thermoelectricity to achieve the cooling process, replacing the existing use of refrigerant fluid and associated compressor and refrigeration components or the use of large quantities of dry ice to create chilled or cooled water. A thermoelectric cooling/heating prototype system has been designed and tested, and successfully demonstrates the temperature of circulating water within small tubes incorporated into a person’s vest undergarment can be used to regulate body temperature. The system briefly comprises: a small reservoir tank of water; a thermoelectric module, heatsink and electronic fan; a small electronic water pump; a proportional, integral, and derivative (PID) controller; interconnecting tubing to carry the circulating water; and a vest undergarment that is worn by the user to help regulate their body temperature. Results presented demonstrate the thermoelectric module successfully cools or heats the water circulating around the vest undergarment, which when worn by a user can be used to lower or increase their external body temperature and improve their temperature comfort levels. The thermoelectric cooling/heating system has several advantages over existing solutions including; a significant decrease in size and weight; system cost; accurate temperature control; ability to provide cooling or heating under user control; no moving parts within the thermoelectric module contributing to high reliability and reduced maintenance requirements; quiet in operation; the elimination of dry ice in the cooling process; and no use of refrigerate fluid or other harmful chemicals. Further work will optimize the design, scale the system to achieve specific cooling/heating targets, and demonstrate the effectiveness of the system in improving a user’s temperature comfort levels.
Thermoelectric water meter energy harvesting
Authors: Gould C A
Published: June 2020

Domestic electronic water meters are installed by water meter utility companies to accurately measure household water usage for billing purposes, progressing from simple electromechanical systems to state-of-the art volumetric electronic smart meters with RF radio transmission, remote reading, and automatic billing capability. The motivation for this work is to replace, or increase the lifetime of, the on-board lithium-ion battery installed in electronic water meters with a thermoelectric energy harvesting solution to create a business advantage. Practical field experiments at several different water meter installations in the UK, USA, and Australia have demonstrated a temperature difference can exist between the top-side and bottom-side of a water meter, and between several different areas of the meter and the surrounding air. This temperature difference can be harnessed to generate electrical power using thermoelectricity. A prototype thermoelectric water meter energy harvesting system has been designed, and experiments demonstrate the system will operate when a temperature difference is present across the thermoelectric module, giving an output voltage of 3.7 V to power the water meter electronics directly or to provide a charge current for the existing lithium-ion battery to increase its lifetime. The work concludes it is feasible, although still challenging, to develop a solution for a novel thermoelectric powered water meter. Further work is required to address the commercial challenges that exist, develop and optimise the prototype solution into a production ready prototype, and conduct further tests using a standard UK domestic water profile at a UK water meter test site.
Coverage measurement and analysis during verification of DUT
Authors: Boiadzhian Armen , Lisik Zbigniew , Hahanova Irina
Published: June 2020

Verification involves checking the compliance of the system with the requirements of its specification at each level of detail. Given a certain complexity inherent in real systems, formal methods are not applicable for such a resister-transistor level (RTL)-description check, since they are associated with extremely high computational complexity. In practice, in this case, the device’s RTL code is checked by applying test stimulus to the RTL model and controlling the response to either the specification or the reference model. The applied techniques for writing and generating tests do not have a priori guarantees covering all possible situations that allow us to identify bugs in design.
On total edge irregularity strength of tadpole chain graph Tr(6, n)
Authors: Nurdini E , Rosyida I , Mulyono
Published: June 2020

Given a graph G(V, E) with a non-empty set of vertices V and a setof edges E. A total labelling f: V ∪ E → {1,2,…, k} is called an edge irregular total labeling if the weight of every edge is distinct. The weight of anedgee, under the total labeling f, is the sum of label of edgee and all labels of vertices that are incident to e. In other words, wt(xy) = f(xy) + f(x) + f(y). The total edge irregularity strength of G, denoted by tes(G) is the minimum k used to label graph G with the edge irregular total labeling. A tadpole chain graph of length r, denoted as Tr
(6, n), is a chain graph that consists of tadpole graph T (6, n) on each block. In this paper, we get

t
e
s
(

T
r

(
6
,
n
)
)
=

⌈

(
6
+
n
)
r
+
2

3

⌉

and construct an algorithm to find it.
Sigma chromatic number of graph coronas involving complete graphs
Authors: Garciano A D , Lagura M C T , Marcelo R M
Published: June 2020

Let c : V(G) → ℕ be a coloring of the vertices in a graph G. For a vertex u in G, the color sum of u, denoted by σ(u), is the sum of the colors of the neighbors of u. The coloring c is called a sigma coloring of G if σ(u) ≠ σ(v) whenever u and v are adjacent vertices in G. The minimum number of colors that can be used in a sigma coloring of G is called the sigma chromatic number of G and is denoted by σ(G). Given two simple, connected graphs G and H, the corona of G and H, denoted by G ⊙ H, is the graph obtained by taking one copy of G and |V(G)| copies of H and where the ith vertex of G is adjacent to every vertex of the ith copy of H. In this study, we will show that for a graph G with |V(G)| ≥ 2, and a complete graph Kn
of order n, n ≤ σ(G ⊙ Kn
) ≤ max {σ(G), n}. In addition, let Pn
and Cn
denote a path and a cycle of order n respectively. If m, n ≥ 3, we will prove that σ(Km
⊙ Pn
) = 2 if and only if

m
≤
n
−
2

⌊

n
4

⌋

+
2

. If n is even, we show that σ(Km
⊙ Cn
) = 2 if and only if

m
≤
n
−
2

⌈

n
4

⌉

+
2

. Furthermore, in the case that n is odd, we show that σ(Km
⊙ Cn
) = 3 if and only if

m
≤
H

(

⌈

n
4

⌉

−
1
,
n
−

⌈

n
4

⌉

)

where H(r, s) denotes the number of lattice points in the convex hull of points on the plane determined by the integer parameters r and s.
Twin chromatic indices of some graphs with maximum degree 3
Authors: Tolentino J D , Marcelo R M , Tolentino M A C
Published: June 2020

Letk≥ 2 be an integer andGbe a connected graph of order at least 3. A twink-edge coloring ofGis a proper edge coloring ofGthat uses colors from ℤkand that induces a proper vertex coloring onGwhere the color of a vertexvis the sum (in ℤk) of the colors of the edges incident withv. The smallest integerkfor whichGhas a twink-edge coloring is the twin chromatic index ofGand is denoted byχt′(G). In this paper, we determine the twin chromatic indices of circulant graphsCn(1,n2), and some generalized Petersen graphs such asGP(3s,k),GP(m, 2), andGP(4s,l) wheren≥ 6 andn≡ 0 (mod 4),s≥ 1,k≢ 0 (mod 3), m ≥ 3 and m ∉ {4, 5}, andlis odd. Moreover, we provide some sufficient conditions for a connected graph with maximum degree 3 to have twin chromatic index greater than 3.
Colour segmentation of Gram-Negative bacteria using graph Quadratic Form and Random Walker
Authors: Satoto B D , Utoyo I , Rulaningtyas R
Published: June 2020

Gram-negative bacteria are one of the bacteria that are often pathogenic to the human body. This bacterium causes resistance due to nosocomial with other Gram-negative bacteria. In the medical stage, the bacteria that cause nosocomial traits removed first before antibiotic therapy carried out on the main bacteria. To identify these bacteria, the clinical laboratory needs to make manual observations under a microscope. The approach taken in this research is using the image processing technique. There are four stages: pre-processing, segmentation, feature extraction, and identification. Segmentation is a stage to emphasize the object sought in an image. In this research, the approach used to capture objects is one of them using the Graph Quadratic Form algorithm. This algorithm chose because it can determine the shortest distance of the object from the nearest node so that the process of convergence of the object search becomes faster. The result is that this algorithm is better than the morphology-based algorithm and the contour-based algorithm, while the number of samples taken from 50 patients affected by Gram-negative bacteria. The image under research has a size of 512x512 pixels, a resolution of 72 dpi with a bit depth of 24. The segmentation process is carried out on Gram-negative bacterial images using two classes producing an average accuracy of 89% to Ground truth.
Characteristic polynomial of anti-adjacency matrix of directed cyclic friendship graph
Authors: Anzana N , Aminah S , Utama S , Silaban D R
Published: June 2020

Graph theory has some applications. One of them is used to do social network analysis as in Facebook with each person as nodes and every like, share, comment, tag as edges. Usually a network can be represented by a graph. Analysing a network is the same as analysing the structure of a graph. A structure of a graph can be analysed through some matrix representations such as anti-adjacency matrix. The entries of the anti-adjacency matrix of a directed graph represent the presence or absence of directed arcs from a vertex to the others. This paper is about the properties of the anti-adjacency matrix of directed cyclic friendship graph, those are the characteristic polynomial and the eigenvalues of the anti-adjacency matrix. The method used to obtain the general form of the coefficients of the characteristic polynomial is by adding up the determinant values of all directed induced subgraphs, cyclic or acyclic, of the directed cyclic friendship graph. Furthermore, the methods used to find theeigenvalues of the anti-adjacency matrix of directed cyclic friendship graph are the substitution method and factorization method. The result of this researcharethe general form of the coefficients of the characteristic polynomial and the general form of the eigenvalues of the anti-adjacency matrix depend on the number of triangles in directed cyclic friendship graph.
The matrix Jacobson graph of fields
Authors: Humaira S , Astuti P , Muchtadi-Alamsyah I , Erfanian A
Published: June 2020

The notion of Jacobson graph and n-array Jacobson graph of a commutative ring were introduced in 2012 and 2018, respectively, by Azimi et al and Ghayour et al. In this article we generalize them to matrix Jacobson graph. Let R be a commutative ring. The matrix Jacobson graph of a ring R, denoted

J

(
R
)

m
×
n

, is defined as a graph with vertex set is the set of matrix of ring without the matrix of its Jacobson such that two distinct vertices A, B are adjacent if and only if 1 − det(AtB) is not a unit of ring. In this article we study the matrix Jacobson graph where the underlying ring R is a finite field. Since any matrix of size m × n over a field F can be considered as a linear mapping from linear space Fm
to Fn
, we employ the structure of linear mappings on finite dimensional vector spaces to derive some properties of square and non square matrix Jacobson graph of fields, including their diameters.
On the set chromatic number of the join and comb product of graphs
Authors: Felipe B C L , Garciano A D , Tolentino M A C
Published: June 2020

A vertex coloring c : V(G) → ℕ of a non-trivial connected graph G is called a set coloring if NC(u) ≠ NC(v) for any pair of adjacent vertices u and v. Here, NC(x) denotes the set of colors assigned to vertices adjacent to x. The set chromatic number of G, denoted by χs
(G), is defined as the fewest number of colors needed to construct a set coloring of G. In this paper, we study the set chromatic number in relation to two graph operations: join and comb prdocut. We determine the set chromatic number of wheels and the join of a bipartite graph and a cycle, the join of two cycles, the join of a complete graph and a bipartite graph, and the join of two bipartite graphs. Moreover, we determine the set chromatic number of the comb product of a complete graph with paths, cycles, and large star graphs.
On Ramsey (P
3, C
7)-minimal graphs
Authors: Muttaqin G A , Rahmadani D , Purwanto  , Sulandra I M
Published: June 2020

Let F, G and H be graphs. Notation F → (G, H) means that there is any two-coloring, say red and blue, of all edges of F which contains red subgraph isomorphic to G or blue subgraph isomorphic to H. The graph F is Ramsey (G, H)-minimal if F → (G, H) but F − e ↛ (G, H) for any e ∈ E(F).The class of all Ramsey (G, H)-minimal graphs will be denoted by R(G, H). According to the previous study, we know that graphs in R(P
3, C
7) have at least 13 edges.In this paper, we find graphs in R(P
3, C
7) having seven vertices and 13 and 14 edges, respectively. Further, we give some necessary conditions for Ramsey (P
3, C
7)-minimal graphs with seven vertices.
On spectra of square edge-corona graphs
Authors: Zulkarnain S R , Rinurwati
Published: June 2020

Given two connected graphs, G and H. The Order and size of Gand H, are u and v, and m and n, respectively. Graph G square edge-corona H, denoted by G ⋄2
H and defined as G ⋄2
H: = (G ⋄ H) ⋄ H, that is a graph obtained from G, the first v-copies of H that is Hh
, with h ∈ {1,2,…, v], and the second v(1 + 2n + m)-copies of H that is Hhk
, with h ∈ {1,2,…, v] and k ∈ {1,2,…,1 + 2n + m] and joining the terminal vertices of eh
∈ E(G), with eh
= ihjh
and ih
, jh
∈ V(G), to all vertices of Hh
, and then joining the terminal vertices of ek
= rksk
, ek
∈ G ⋄ H, to all vertices of Hhk
. In this paper, the spectrum of the adjacency, Laplacian, and signless-Laplacian matrices of the graph G ⋄2
H will be analyzed further.
Local super antimagic total vertex coloring of some wheel related graphs
Authors: Pratama S A , Setiawani S , Slamin
Published: June 2020

Let G be a simple and finite graph with vertex set V and edge set E. The local antimagic total labeling of G is a map from V ∪ E to the set of positive integers from 1 to |V| + |E| such that the weight of two adjacent vertices are distinct. The weight of a vertex v is calculated by the sum of the label of the vertex v and the labels of all edges incident to it. If the vertices of G is labelled by the smallest labels, that is, {1, 2,…, |V|}, then the such labeling is called local super antimagic total labeling. Thus, the local super antimagic total labeling induces a proper vertex coloring of G where the vertex v is colored by the weight of vertex v. The minimum number of colors taken over all colorings induced by super local antimagic total labeling of G, is called local super antimagic total chromatic number of graph G, and denoted by χlsat
(G). In this paper, we consider the local super antimagic total chromatic number of some wheel related graphs such as fans, even gear graphs, and sun flower graphs.
Odd harmonious labeling on squid graph and double squid graph
Authors: Febriana F , Sugeng K A
Published: June 2020

An injective functionffrom set of vertices in graphGto a set of {0,1,…,|E| − 1} is called an odd harmonious labeling if the functionfinduced the edge functionf* from the set of edges ofGto a set of odd positive integer number {1,3,5,…,2|E| − 1} withf*(xy) =f(x) +f(y) for every edgexyinE.Graph that has an odd harmonious labeling is called odd harmonious graph. The squid graphTn,kis a graph which is obtained from a cycleCnand we addkpendant to one vertex of the cycle. It is known thatCnis an odd harmonious graph if and only ifn= 0 mod 4. However, by adding at least one pendant in the cycle graph, we can label the new graph odd harmoniously for all even number of vertices. In this paper, we showed that the graphTn,kandT2n,kare an odd harmonious graph, forn= 0 (mod 2),n≥ 4 andk≥ 1. The construction of the odd harmonious labeling of the graphTn,kandT2n,kare inspired by the odd harmonious labeling ofCnforn= 0(mod 4).
Unicyclic Ramsey (P
3, Pn
)-minimal graphs obtained from trees in the same class
Authors: Rahmadani D , Assiyatun H , Baskoro E T
Published: June 2020

If G, H and F are finite and simple graphs, notation F → (G, H) means that for any red-blue coloring of the edges of F, there is either a red subgraph isomorphic to G or a blue subgraph isomorphic to H. A graph F is a Ramsey (G, H)-minimal graph if F → (G, H) and for every e ∈ E(F), graph F − e ↛ (G, H). The class of all Ramsey (G, H)-minimal graphs (up to isomorphism) will be denoted by R(G, H). The characterization of all graphs in the infinite class R(P
3, Pn
) is still open, for any n ≥ 4. In this paper, we find an infinite families of trees in R(P
3, P
5). We determine how to construct unicyclic graphs in R(P
3, Pn
), for any n ≥ 5 from trees in the same class. Further, we give some properties for the unicyclic graphs constructed from trees in R(P
3, Pn
), for any n ≥ 5.
On the super

H

-decomposition local antimagic total labeling of subdivision graph
Authors: Fauziah S L , Dafik  , Agustin I H , Alfarisi R
Published: June 2020

We assume that G = G(V, E) is a finite, simple, and undirected graph with V as set of vertices and E as set of edges. A bijection g : V (G) ∪ E(G) → {1, 2, 3, …|V(G)| + |E(G)} is called a super

H

-decomposition local antimagic total labeling for any two adjacent subgraph

ℋ
i

and

ℋ
j

,

w
(

ℋ
i

)
≠
w
(

ℋ
j

)

, where

w
(
ℋ
)
=

∑

v
∈
V
(
ℋ
)

f
(
v
)

+

∑

e
∈
E
(
ℋ
)

f
(
e
)

. The chromatic number of super

H

-decomposition local antimagic total labeling is minimum number of colors in super

H

-decomposition local antimagic total labeling and denoted by

γ

l
a
t
ℋ

(
G
)

. In this paper, we used some subdivision graph. Such as subdivision of star graph (S(Sn
)), subdivision of sun graph (M(Mn
)), subdivision of wheel graph (S(Wn
)). The subdivision graph S(G) of a graph G is the graph obtained from G by replacing each of its edges by a path of length two.
Elegant labeling of some graphs
Authors: Prihandini R M , Dafik  , Agustin I H , Alfarisi R , Adawiyah R
Published: June 2020

An elegant labeling on graph G with α vertices and β edges is an injective (one-to-one) mapping from the set of vertices V(G) to the set of non-negative integers {0,1, 2, 3, …,β} in such a way that the set of values on the edges obtained by the sums mod β + 1 of the labels of their end vertices is {1, 2, 3,4,…, β}. The purpose of this research is to prove that several graphs, namely diamond ladder admit an elegant labeling. We also look for relationships between Edge Antimagic Vertex Labeling and Elegant Labeling.