bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of the iron oxide phases formed during the synthesis of core–shell FexOy@C nanoparticles modified with Ag
Authors: Petrov D A , Lin C -R , Ivantsov R D , Ovchinnikov S G , Zharkov S M , Yurkin G Y , Velikanov D A , Knyazev Y V , Molokeev M S , Tseng Y -T , Lin E -S , Edelman I S , Baskakov A O , Starchikov S S , Lyubutin I S
Published: June 2020

Core–shell FexOy@C nanoparticles (NPs) modified with Ag were studied with x-ray diffraction, transmission electron microscopy, energy dispersive elemental mapping, Mössbauer spectroscopy, static magnetic measurements, and optical magnetic circular dichroism (MCD). FexOy@C NPs synthesized by the pyrolysis process of the mixture of Fe(NO3)3 · 9H2O with oleylamine and oleic acid were added to a heated mixture of oleylamine and AgNO3 in different concentrations. The final product was a mixture of iron oxide crystalline NPs in an amorphous carbon shell and Ag crystalline NPs. The iron oxide NPs were presented by two magnetic phases with extremely close crystal structures: Fe3O4 and γ-Fe2O3. Ag is shown to form crystalline NPs located very close to the iron oxide NPs. An assumption is made about the formation of hybrid FexOy@C-Ag NPs. Correlations were obtained between the Ag concentration in the fabricated samples, their magnetic properties and the MCD spectrum shape. Introducing Ag led to a approximately linear decrease of the NPs saturation magnetization depending upon the Ag concentration, it also resulted into the MCD spectrum shift to the lower light wave energies. MCD was also studied for the Fe3O4@C NPs synthesized earlier with the same one-step process using different heat treatment temperatures, and MCD spectra were compared for two series of NPs. A possible contribution of the surface plasmon excitation in Ag NPs to the MCD spectrum of the FexOy@C-Ag NPs is discussed.
Fabrication and photocatalytic characterization of SnO2 and SnO2/Tio2 nanostructure films
Authors: Abbas Khaldoon N. , Hussain Nedal A. , Nusseif Asmaa D. , Hussein Emad H. , Aziz Wisam J. , Salim Ali A.
Published: June 2020

Pure spherical-like SnO2 and agglomerated spherical SnO2/TiO2 nanostructures (NS) films were effectively synthesized via hydrothermal route and modest combination of pulse laser ablation besides hydrothermal (PLAL-H) methods, respectively. The as-prepared samples were deposited on glass substrates at growth temperature 100 °C and characterized by FESEM, X-ray diffraction, and UV-Vis absorption and Photoluminescence (PL) measurements. Both samples exhibit a pure tetragonal rutile and anatase polycrystalline structure. The PL spectrum of pure SnO2 Ns reveals five emission peaks in UV and visible regions. In contrast, a red shift in UV emission peak was clearly observed in SnO2/TiO2 nanocomposite spectrum and disappeared all visible emission peaks. Moreover, the samples as photocatalysts films were examined under sunlight irradiation driven photodegradation of methylene blue (MB) dye. The findings exposed that the photodegradation efficiency toward MB dye at maximum irradiation time 150 min was mostly similar around 21.5 % of both as-growth films.
Study on The Third-Order NLO Properties of Trace Metal Ions in Nitric Acid Solution by Closed-Aperture Z-scan Technique
Authors: Izz Rosli Muhammad , Awalludin Afiq , Duralim Maisarah , Abdullah Mundzir , Safwan Abd Aziz Muhammad
Published: June 2020

Discovery of materials which exhibit large real third-order optical nonlinearities have recently become the topic of a broad scientific interest, due to its potential applications in many areas especially in the field of all-optical signal-processing. Here in this work, we report a preliminary investigation on the third-order nonlinear optical (NLO) response of different type of trace metal ions in nitric acid standard solution. A facile and rapid single beam z-scan technique incorporating 532nm diode pump solid state laser was employed to study the response of Lead (Pb), Cadmium (Cd), Mercury (Hg), Zinc (Zn), Aluminum (Al) ions towards NLO properties. Nonlinear refraction (NLR) response of the heavy metal samples were recorded from closed-aperture output and the maximum values of nonlinear refractive index,n2for all Pb, Cd, Hg, Zn, Al were recorded at 1.96355×10−9, 3.38228×10−9, 9.36907×10−9, 8.67559×10−10,3.28211×10−9cm2W−1respectively. Based on the experimental findings, the negative sign of the nonlinear refractive index values successfully indicates that the samples exhibit nonlinear self-defocusing effect, which is further expected to have potential applications in all-optical devices.
Non-contact Fiber Optic Displacement Sensor for Sugar Concentration Detection
Authors: Rahman Johari Abdul , Krishnan Ganesan , Bakhtiar Hazri , Hani Jameela Sapingi Husni , Wadi Harun Sulaiman
Published: June 2020

A non-contact fiber optic displacement sensor was used for sugar concentration sensing. A concentric fiber optic bundle and sucrose solutions were used as the fiber probe and sugar samples respectively. Concentration of samples used were in the range of 9% to 33% weight percentages. The fiber probe was displaced above the sample surfaces and displacement curves were recorded. There were two peaks were observed in the displacement curve for each sample. The distance between peaks increases linearly as concentration increases and it was used to evaluate the sensing performance. In term of the performance, the sensitivity and linearity obtained were 0.08295 mm/% and 96% respectively.
Pulse laser ablated growth of Au-Ag nanocolloids: Basic insight on physiochemical attributes
Authors: Salim A A , Ghoshal S K , Bakhtiar Hazri , Krishnan G , Safwan aziz M , Sapingi H H J
Published: June 2020

Despite considerable research the evidence around the wide applications in the nanomedicine and nanophotonic area of gold-silver (Au–Ag) nanocolloids remains equivocal and under exploration. Due to their physical properties, enhanced permeability, high fluorescent, surface area to volume ratio, retention effect, localized surface plasmon resonance (LSPR) and controlled perfusion of drugs, made Au–Ag nanoparticles is over interested. Hence, we produced Au–Ag nanocolloids using nanosecond pulse laser ablation in liquid (NPLAL) technique. Targets of Au and Ag were submerged individually inside the cubic vessel fulfilled by 8 mL of glycol liquid media and vertically ablated with different pulse laser ablation (PLA) energy (50, 100, 150 and 200 mJ). The influence of the PLA energy (at fundamental wavelength 1064 nm) on the optical properties, morphology, particle size distribution, and chemical structure of the obtained colloidal Au–Au NPs was established. UV-Vis and FTIR spectrophotometers have been utilized to determine the absorbance characteristics and chemical functional groups of Au–Ag nanostructures, respectively. The attained of Au-Ag nanostructure exhibits a single-surface plasmon resonance (SPR) band, positioned between SPR bands of the monometallic and a surface bonding functional group (e.g. carboxyl or hydroxy groups). The proposed technique can be a basis for the developing complex compositions/colloids with unique and optimal physical properties may use for developing future nanomedicinal and nanophotonics.
Fuzzy Logic Controller for Classroom Air Conditioner
Authors: Riyadh Waheed Safa , Mundher Adnan Myasar , Mohd Suaib Norhaida , Shafry Mohd Rahim Mohd
Published: June 2020

In the modernized era, the air conditioners are an integrated part of comfort living especially in hot climates. They are used to control the interior spatial temperature, relative humidity, degree of cleanliness, and speed of air streaming. The automatic controllers are the key elements of the modern air conditioning systems that ensure the reliable operation, improved quality, low operation cost, and better security. Thus, the realization, design, and application of the controller systems require the exact specifications of the involved processes. In this regard, controllers based on the fuzzy logic (FL) are prospective for air conditioners due to the easy accessibility of different output levels. Furthermore, using the FL it is possible to scale and control the users’ air processing demand depending on the temperature and relative humidity of the space. Based on these factors, this paper reports the design and performance evaluation of a FL based controller useful for air conditioners when implemented in the classroom setting. This FL based control system can reduce the complexity of programming thereby can be executed on general microcontrollers utilized in the control panels of classroom air conditioner. The results revealed the outperforming nature of the FL based controllers over other traditional controllers used to adjust the indoor temperature and relative humidity by air conditioners.
Realization of efficient red laser using europium doped new boro-telluro-dolomite glass hosts: Ag nanoparticles functionality
Authors: Bulus I , Bhaktiar H , Hussin R , Danmallam I M , Ghoshal S K
Published: June 2020

Achieving highly efficient visible red emission with high color purity from the rare earth ions doped glasses containing metallic nanoparticles is of scholastic significance in the quest of novel laser glass host. Stimulated by this demand, we synthesized some new class of silver nanoparticles (Ag – NPs) embedded europium ions (Eu3+) doped boro – telluro – dolomite glasses (hereafter coded as BTDEAx, where x = 0.0, 0.1, 0.3, 0.5, 0.8 and 1.0 mol%) by convectional melt quenching method. These glasses were optically characterized using UV – Vis – NIR absorption and photoluminescence (PL) spectroscopy’s to ascertain their lasing candidacy. The absorption spectra of the Eu3+ ion free sample (BTDA0.8) disclosed a single surface plasmon band characteristic of Ag – NPs at 464 nm. Meanwhile, the visible emission intensities (excited with 467 nm wavelength) of the glasses due to Ag – NPs inclusion were greatly intensified. Of all glasses, the sample prepared with 0.8 mol% of Ag NPs (BTDEAg0.8) revealed highest PL intensity enhancement. Furthermore, the attainment of high color purity (97.037 %) detected from the CIE diagram with chromaticity coordinates (0.63765, 0.36094) close to ideal red color phosphor (0.67, 0.33) indeed approved the suitability of the proposed glasses for solid state red laser construction.
Effect of gas concentration on the electron transport and the plasma parameters of the CO2 gas mixture
Authors: Kaittan Fayyadh Ibrahim , Saud oraibi Nissan , Mutar Oufi Attarid , Ibrahim Alwan Ahmed , Abdulhasan Jawad A.
Published: June 2020

Electron Swarm Parameters in plasma gas mixtures of Co2 have been calculated. Studies focused on four gas mixtures with Co2, He, and N2 in the ratio 5%: 55%: 40%, 2.5%: 45%: 52.5%, 10%: 50%: 40% and 40%: 40%: 20% respectively. Calculations of the electron energy distribution function f (ε), drift velocity Vd, mobility μ, electron diffusion D, D/μ, electron average energy <ε> and electric field E in the range of electric field to gas number density ratio E/N from 1×10−19 to 5×10−15 at 300 0K were reported in this work. The theoretical calculations shown helium has a good effect on the electrons transition parameters of Co2 laser. Furthermore, at low energy, the total collision rate is increasing slowly for higher electron energy.
Parametric analysis of the Lateral Distribution Function of Cherenkov light for Yakutsk EAS Array in the Energy Range 1–20 PeV
Authors: Al-Zubaidi Falah , Al-Rubaiee A. A. , Hariharan B.
Published: June 2020

In this research, the simulation of lateral distribution function (LDF) of Cherenkov radiation was performed using CORSIKA software for two hadronic models QGSJET and GHEISHA. This simulation was performed for several elementary particles such as protons, iron nuclei, electrons and gamma quanta, in the range of energies 1-20 PeV for three zenith angles 0°, 20° and 30°. A parameterization of Cherenkov light LDF was performed for that simulated curves using Lorentzian function. The comparison between the obtained results for LDF of Cherenkov light with that measured with Yakutsk EAS array gave a good agreement within the distances of 100-1000 m from the shower axis.
Few Layer Molybdenum Selenide Saturable Absorber using Optical Deposition Technique for Q-switched Ytterbium Pulses Laser Generation
Authors: Aizi Mat Salim Muhammad , Razalli Azzuhri Saaidal , Afiq Ismail Mohd , Ab. Razak Mohd. Zulhakimi
Published: June 2020

We have successfully generated a Q-switched ytterbium-doped fiber laser pulses using few layers of Molybdenum Selenide (MoSe2) as saturable absorber (SA). The setup was a ring fiber laser cavity with few-layer MoSe2, deposited onto a fiber ferrule using an optical deposition technique. A stable pulses started at input power of 68.8 mW with repetition rate ranging from 14.2 kHz to 34.0 kHz was achieved with highest pulse energy, shortest pulse width and highest output power of 3.6 nJ, 4.4 µs and 0.12 mW were observed, respectively.
Effect of laser energy and wavelength on average size of gold nanoparticles synthesized by pulsed laser ablation in deionized water
Authors: Jamaludin N , Chaudhary K T , Haider Z , Duralim M , Ismail F D , Roslan M S , Amira N H , Ali J
Published: June 2020

In this paper, the effect of Nd:YAG laser wavelength and energy on the synthesis of gold nanoparticles is reported. Gold nanoparticles colloidal solutions were prepared by pulsed laser ablation of gold target in deionized water. The Nd:YAG laser with repetition rate of 1 Hz was assigned to supply energy at fundamental and second harmonic wavelengths i.e., 1064 nm and 532 nm, respectively. Synthesized nanoparticles were characterized using particle size analyzer (PSA). Four different laser energies were used to ablate the samples and synthesize gold nanoparticles. The average size of gold nanoparticles was found to decrease with increasing laser energy. The gold nanoparticles of smaller size were obtained when the target was ablated with 532nm wavelength of Nd:YAG laser. Higher laser energies and efficient absorption of 532 nm wavelength resulted in size reduction by fragmentation of colloidal nanoparticles.
The tissue temperature during injection of drug solution into it as an integral indicator of rheology
Authors: Urakov A , Gurevich K , Alies M , Reshetnikov A , Kasatkin A , Urakova N
Published: June 2020

The dynamics of local temperature in the area of injection of drug solutions with regard to their physical and chemical properties is studied. It is shown that infrared thermography allows to visualize the processes of intra tissue rheology of drugs both when the temperature of injected drugs differs from the local temperature of tissues in the injection area and when their temperatures are equal. Methods of infrared diagnostics of tissue homogeneity, as well as methods for identifying, specifying the localization, shape and size of tumors, foreign bodies and local inflammations have been developed. It is shown that artificial temperature contrast of veins filled with blood and/or drug solutions in relation to the tissues surrounding them allows to visualize these structures using a thermal imager in real time. It is established that the dynamics of the local temperature of tissues at the injection sites of drug solutions depends not only on the temperature of the injected drugs, but also on the presence and severity of their local irritant effect. It is shown that the local irritating effect of drugs is manifested in the places of their injections by local hyperthermia, hyperemia, swelling and soreness. A direct dependence of the severity of the local irritant effect of drugs on the value of the total concentration of ingredients and the degree of hyperosmotic activity of solutions was established. Therefore, dilution of drugs with water is a way to reduce their local irritant effect.
Simulation of the residual stress in a multi-pass oil and gas pipe weld joint
Authors: Hasan Alhafadhi Mahmood , Krallics Gyorgy
Published: June 2020

In this paper, a welding simulation procedure is developed using the FE software MSC Marc to predict the residual stresses.Numerical simulation was used to predict the thermal, mechanical and residual stresses behaviour in dissimilar material welded pipes which were found to be in good concurrence with experiments. Both two-dimensional FE model (2D) and three-dimensional FE model (3D) models are used to simulate the residual stressesin different directions in several regions of the weld zone under the same welding conditions. The 2D modelwas used toreduce the time and cost of numerical simulation.The aimof the present work is to understand the evolution of residual stresses (axial, radial and hoop stresses) in weldments. The results of thesimulationreveal that the hoop and the axial residual stresses around the weld region arenoticeablyvarying from those in the steady range.
Clay-cement suspensions based on Belchatow and Patoka polymineral clays – rheological characteristics
Authors: Litwinek-Rozbicka E , Izak P , ŁWójcik  , Mastalska-Popławska J
Published: June 2020

The results of studies concerning freshly prepared clay-cement sealing suspensions based on Bełchatów and Patoka polymineral clays, Portland cement and the addition of sodium water glass as the initiator of the hydration process were reported. Flow curves were determined in a coaxial cylinder system. On their basis, power of destruction and rebuilding of the thixotropic structure was calculated. Changes of the elasticity modulus G’ and viscosity modulus G’' were determined by oscillatory measurements in the plate - plate system at variable frequencies. The influence of the type of clay mineral and its content on the tendency to form a thixotropic structure was defined.
Rheology of uncured magnetorheological elastomers
Authors: Moucka R , Sedlacik M , Ronzova A
Published: June 2020

The aim of this paper is to study rheological properties of uncured magnetorheological elastomers comprising iron particles dispersed in silicon elastomer in relation to particle rearrangement by external magnetic field into oriented structures as this process is strongly affected by viscosity. Studied systems vary in used filler volume concentration (0 to 30 vol. %). From measured flow curves flow consistency index is extracted first by fitting experimental data to Herschel-Bulkley model followed by applying two concentration dependency models (Maron-Pierce and Krieger-Dougherty) to normed consistency. Results and model predictions are discussed.
Rheology Behaviour and Mechanical properties of Poly(vinyl alcohol) Membranes Modified with Nanodiamonds
Authors: Remiš Tomáš , Kadlec Jaroslav , Kovářík Tomáš
Published: June 2020

Poly (vinyl alcohol) (PVA) membranes have found wide application in biomedicine and pharmacy for their unique properties such as biocompatibility, elasticity and the ability to absorb large amounts of water. Also carbon nanomaterials have shown great potential in a number of applications in regenerative medicine. Nanodiamonds (ND) are a unique class of carbon nanoparticles that have become known thanks to their biocompatibility, highly functional surface and unique physical, chemical and optical properties. Nanocomposite membranes based on PVA and ND were prepared by a solution casting method to achieve an even distribution of ND in the PVA matrix. The resulting nanocomposites have excellent properties derived from ND and PVA. The mechanical properties of the membranes improved significantly with an increase in ND, suggesting a strong chemical interaction between ND and PVA. The SEM showed a uniform distribution of ND in the PVA membrane. From the results of the work we assume that ND are a suitable nano-filler for PVA membranes. This work examines the properties of ND-reinforced PVA membranes and their potential use in biomedical applications.
Using Crumb Rubber to Improve the Bituminous Mixes: Experimental Investigation of Rutting Behavior of Flexible Asphalt Mix for Road Construction
Authors: Qassim Al-Salih Wissam
Published: June 2020

Tires that are simply thrown away are a serious environmental problem and safe disposal is a difficult problem. Using the crumb rubber (CR) obtained from shredding of those scrap tires in roads is an alternative solution to their safe disposal. On the other side, excessive rutting in the bituminous layer is a structural defect associated with functional implications. Wheel loads and high pavement temperatures are environmental factors which the main cause of premature rutting. Modified binders and rut resistant mixes especially gradations can reduce premature rutting. The object of the paper to solve two main problems: firstly, the solution to the problem of the tires waste to safe disposal and; secondly, to study the rutting behaviour in bituminous mixes modified by tires waste in CR form. In this paper, two types of bituminous mixes, stone matrix asphalt and bituminous concrete those are used to carry wheel tracking test. The results are shown by using Marshall Test that 6% of CR content by weight if normal binder 60/70 content and optimum binder content for the binder in bituminous mixes is 5.1% & 5.5% by weight of mix is have improved the bituminous mixes. In addition, results indicated that the mixes prepared with a modified binder by CR are good in forming rut resisting mixes. The benefit of this study is the tires waste disposal in an environment-friendly way and better road to withstand rutting.
Numerically simulated prediction of residual stresses in welding considering phase transformation effects
Authors: Hasan Alhafadhi Mahmood , Krallics Gyorgy
Published: June 2020

This work deals with investigating the effects of solid-state phase transformation on residual stresses during the welding of low carbon and high carbon steels. In this study, depending on MSC Marc code, the simulation considers the local microstructure properties changes due to the thermal welding cycles. A sequentially coupled thermal and mechanical 2-D finite element model (FEM) was used. In FEM, phase transformation temperature diagrams are used to anticipate the amount of martensite in the fusion zone (FZ), and heat affects zone (HAZ). The simulation results demonstrated that the residual stress in low carbon steel is not affected by the volume change caused bythe austenite-martensite transformation. In contrarily,the residual stressesin the high carbon steel are considerably influenced by the martensitic transformation.
About mechanical behaviour of metal matrix composites under shock wave loading
Authors: Karakulov V V , Yu Smolin I , Kulkov S N
Published: June 2020

In this work the results of studying of the mechanical behaviour of metal-ceramic composites with an aluminium matrix on meso-scale level are submitted. Computer simulation of mechanical reaction of representative volume of composite material, considered as ensemble of the interacting structural elements (ceramic particles and metal matrix), is used for studying mechanisms of deformation on meso-scale level of metal-ceramic composites under the loading by shock waves. The mechanical behaviour of aluminium matrix is described by the model of the damaged elastic-plastic medium. The model of the damaged brittle solid is used for ceramics. The absence of macroscopic and mesoscopic voids and cracks in the material before loading is assumed. Ideal adhesion of ceramic material to metal is supposed at the initial condition. The problem is solved in 2D statement with application of finite-difference method. Results of numerical simulation of the mechanical behaviour of metal-ceramic composites under shock wave loading have shown the formation of non-stationary and essentially non-uniform fields of stresses and strains at the meso-scale level. The generation of a dissipative structure on the meso-scale level of the composites under shock wave loading was revealed in the simulations.
The features of fracture processes of the ceramic composite
Authors: Mikushina V A
Published: June 2020

The phenomenon of material fracture spans many different length scales. The paper is devoted to the numerical investigation of the features of fracture processes in alumina-zirconia composite ceramics at the mesoscale subjected to uniaxial compression. A structural model of the composite mesovolume based on the experimental SEM image is adopted. The mechanical behavior of the composite is described by a constitutive model of the damageable elastic-brittle medium. Two local fracture criteria are used that are based on the limit values of damage and tensile pressure. The energy dissipation process in the ceramic composite mesovolume during damage accumulation is analyzed. It is shown that the damage accumulation results in nonlinear dissipation of potential energy and the following kinetic energy increase. The last is accompanied by the appearance and growth of cracks in matrix and inclusions at the final stages of deformation.
Formation and characterisation of cobalt depleted outermost layer of WC–Co composite materials
Authors: Rugóczky Peter , Muránszky Gábor , Lassú Gábor , Lakatos János
Published: June 2020

The cobalt depleted layer of WC–Co composite materials was investigated after selective cobalt etching in diluted Caro’s acid. The time dependence of Co etching and the thickness of the etched layer was determined by using Glow Discharge Optical Emission Spectrometer (GD-OES) depth profiling as well as by calculation method based on determination of the dissolved Co by Atomic Absorption Spectrophotometric (AAS) measurement. The integrity of the modified outermost layer of the WC–Co composite materials were qualified using Rockwell C indentation test. This test methods were found usable for optimisation of the pre-treatment applied before the diamond thin film deposition.
Microstructural evaluation and thermal properties of sol-gel derived silica-titania based porous glasses
Authors: Deshmukh Kalim , Kovářík Tomáš , Křenek Tomáš , Stich Theresia , Docheva Denitsa
Published: June 2020

In recent years, the sol-gel synthesis of porous glasses has drawn widespread attention owing to the convenience and versatility of the sol-gel method. The sol-gel synthesis process mainly involves hydrolysis and condensation of precursors followed by drying and stabilization. In the present study, silica-titania (Si-Ti) based porous glasses with different compositions were synthesized using the sol-gel method. In general, the final properties of solgel derived glasses significantly depend on the characteristics such as pore structure, pore size, morphology and the compositions of the precursor materials. The influence of these processing parameters on the microstructural and thermal properties of Si-Ti based glasses has been investigated. The microstructures of the synthesized Si-Ti based porous glasses were investigated using scanning electron microscopy (SEM) and the thermal properties were evaluated using thermogravimetric analysis (TGA) and thermomechanical analysis (TMA). The main objective of the present study is to utilize these Si-Ti porous glasses as a potential biomaterial for bone tissue regeneration. Therefore, to understand this facet of Si-Ti porous glasses, it is essential to investigate their physical and microstructural properties.
The effect of expanded perlite on fired clay bricks
Authors: Hamza Alexandra , Kocserha István
Published: June 2020

Nowadays stricter energy regulations are compelling us to further improve the thermal insulation performance of current building materials. In this study we investigated the possibility of improving the thermal insulating performance of fired clay bricks. In our work we used two types of additives: sawdust, which is a general additive, and expanded perlite, which is typically a synthetic additive based on SiO2 and Al2O3. Sawdust and expanded perlite in amounts varying between 3.35-6.5 wt% were mixed into a clay masses to prepare test samples by pan mill. The moisture content of the clay masses was 25 wt%. Samples were prepared using a laboratory vacuum extruder, after which they were dried, and then sintered at 880 °C. The fired specimens were measured for firing shrinkage, water absorption, bulk density, and compressive strength. Furthermore, we determined the thermal conductivity of the specimens. The purpose of our research was to examine the usability of expanded perlite as an additive in brick manufacturing, and also to compare the results with sawdust, one of the most popular additives. In addition, measurements were made using the two additives together.
The Use of Si-B Alloys in Thermal Energy Storage System
Authors: Meng Jiao Jian , Grorud Bettina , Safarian Jafar , Tangstad Merete
Published: June 2020

Si-B alloys are considered as phase change materials (PCMs) in the thermal energy storage (TES) systems due to their high latent heats and moderate temperatures. In order to successful apply them, proper Si-B alloy composition and a suitable ceramic refractory material that can survive long time corrosion at high temperatures should be determined. Here, we investigate serials of Si-B alloys with the B range of 2-11 mass % in graphite crucibles in the temperature range 1450-1750 °C. This work shows that the interaction between Si-B alloys and graphite goes into two stages. Single SiC is formed at the interface at the B content of 2 mass %. SiC and B4C are produced at the interface at the B contents of higher than 5 mass %. Additionally, the results of structural characterization are supported by thermodynamic calculation. These results provide reliable data in the use of Si-B alloys as PCMs in the TES systems.
Effect of activation and exfoliation on the formation of carbon nanosheets derived from natural materials
Authors: Nuilek K , Simon A , Kurovics E , Ibrahim J F M , Varanasi D , Baumli P
Published: June 2020

Carbon is abundantly found in nature with a wide range of applications. It can be synthesized through physical and chemical processes. Chemical activation is considered as a very efficient method to obtain carbon with high surface area and narrow micropore distribution. Among all the chemical activating agents, alkaline hydroxides such as potassium hydroxide (KOH) or sodium hydroxide (NaOH) are reported to be of high interest in the production of carbon with higher performance. In our research, Nettle stem and peanut shell (natural materials) were used as raw materials for the preparation of carbon. Natural structures of nettle and peanut shell consists of cellulose, which is an important precursor in the preparation of highly ordered carbon nanosheets. Aqueous solutions of KOH and NaOH were used for activation and sulphuric acid (H2SO4) was used for exfoliation. The process employed here has yielded a high percentage of carbon nanostructured particles.
The role of purity level in foundry silica sand on its thermal properties
Authors: Svidró Judit , Tamás Svidró József , Diószegi Attila
Published: June 2020

Silica sand is the most commonly used mineral for molding and core making applications in foundry technology due to its availability, thermal and chemical attributes. However, there are many additional requirements foundry sands need to meet regarding their sizing, chemical purity, physical durability and thermal properties. This research studies the thermophysical properties of a foundry silica sand comprehensively. After separating one sand batch into numerous grain size ranges, the chemical composition and thermophysical properties of the fractions were investigated, respectively. By means of this approach, the chemical properties and thermal behavior can be directly linked. The silicon dioxide content shows a strong correlation with the thermal expansion properties of the various fractions. The results give a better understanding of the high temperature behavior of foundry silica sands and clarify the role of factors affecting their thermophysical properties.
The content of the adsorption centers of high-silica porous glasses
Authors: Tsyganova T A , Mjakin S V , Kostyreva T G
Published: June 2020

Changes in the specific surface, pore size and content of Lewis (siloxane) and Brønsted (silanol) surface groups for high-silica nanoporous glass with a sponge-corpuscular structure depending on their thickness and storage time are studied and interpreted in terms of porous structure features, hydration and aging effects.
Laser ablation of silicon monoxide and titanium monoxide in liquid: formation of mixed colloidal dispersion with photocatalytic activity
Authors: Vála Lukáš , Vavruňková Veronika , Jandová Věra , Křenek Tomáš
Published: June 2020

Silica–titania mixed oxides and composites have been extensively studied, whereas to the titanium monoxide (TiO) –silicon monoxide (SiO) counterparts has been devoted very little attention. Laser ablation of SiO and TiO in liquids is in according with literature completely unexplored. Here we report on Nd:YAG pulse laser ablation of SiO and TiO in ethanol which allows generation of SiO- and TiO-based nanoparticles and their agglomerates.

Mixed SiO-TiO colloid has been prepared by simple mixing of ablatively prepared individual colloids in 1:1 volume ratio. Measurement of size distribution by Dynamic Light Scattering (DLS) determines sizes of 24.85 nm and 262.3 nm for SiO colloid, 494.8 nm for TiO colloid and 35.2 nm and 397.5 nm for mixed colloid. Zeta potential values suggest incipient instability for all measured systems. Morphology of the particles captured on Ta substrate by evaporation of ethanol was studied using Scanning Electron Microscopy (SEM). Round-shaped, oval, and sheet-like particles and their agglomerates have been observed. Raman spectroscopy of the mixed SiO-TiO colloid revealed multiphase structure consisting of anatase and/or rutile, crystalline and amorphous silicon and silica and crystalline and amorphous titanium silicide TiSi2. Formation of TiSi2 demonstrates unexpected low temperature disproportionation of SiO and TiO-based species and mutual reducing interactions. Catalytic activity of individual SiO and TiO colloids and of their mixture has been tested in terms of methylene blue (MB) degradation under the daylight. TiO-SiO mixture exhibits higher solar-light catalytic activity compared to individual colloids which could by explain by the presence of highly photocatalytic TiSi2. These results represent potential of SiO and TiO reducing interactions which are favorable for generation of photocatalytic materials for water remediation.
Estimating domestic self-supply groundwater use in urban continental Africa
Authors: Chávez García Silva Rafael , Grönwall Jenny , van der Kwast Johannes , Danert Kerstin , Foppen Jan Willem
Published: June 2020

Self-supply of groundwater for domestic use in urban sub-Saharan Africa (SSA) is common, but the extent to which it is practiced is unknown. We developed an open data based GIS method for continental Africa (without islands) using groundwater storage, depth to groundwater, aquifer productivity, and population density data. Furthermore, we developed proxies for public supply network coverage and socio-economic status, incorporating restriction measures for groundwater use. Our results indicate that in 2015 about 369 million urban inhabitants (∼79% of the total urban population) of continental Africa could potentially supply themselves with groundwater. However, the likely number of urban inhabitants using groundwater obtained via self-supply was less: about 150 million (∼32% of the total urban population). With the novel GIS based methodology presented here, the urban population using self-supply groundwater for domestic use can be determined, which is essential to inform policy and practice, and to influence public investment.
Analysis of Recharge Area Potential of Upper Cisadane Watershed
Authors: Mahera Sugih , Murtilaksono Kukuh , Tarigan Suria D.
Published: June 2020

This research is being conducted on Upper Cisadane Watershed, Bogor, West Java Province. The aim of this research is to investigate the recharge area and analyze the recharge potential. The data consisted of infiltration rate, slope, soil type, and existing landuse as land unit approach which is collected by purposive sampling. Beside that, climate data were collected to estimate the evaporation. The analysis of the data use SCS-CN method to assess the volume of surface runoff, Penman-Monteith method to asseess the evaporation, and Water Balance Method to asseess the groundwater as the recharge potention. The recharge area would be classified into several areas into the highest to the lowest recharging area. The result of this study would be the total of groundwater fluxas the recharge potential based on each classified recharge area. The condition ofrecharge area could be one of the reasoning in develeoping the urban water system. The land with the good condition has surplus as ΔS=490,26 mm, and the critical one has deficit as ΔS=(-)543,49. The condition of the highest recharghing area would be analysed as the criteria of potential recharging area and the area should be managed well in the future. The condition of the lowest recharghing area would be restored depend on its problem.
Spatial interaction of groundwater and surface topographic using geographically weighted regression in built-up area
Authors: Mulyadi A , Dede M , Widiawaty M A
Published: June 2020

Groundwater is a primary water resource for human living. In Indonesia, excessive exploitation of groundwater generally occurs in the built-up area due to over-discharge processes characterized by a cone of depression. This research revealed the spatial interaction between groundwater levels and surface topographic using geographically weighted regression in built-up area. Groundwater levels data are obtained from 72 wells in Cikembang, Bandung Regency, whereas surface topographic based on BIG’s DEMNas data which has 8 meters spatial resolution. This study showed significant spatial interaction between groundwater levels and surface topographic in the built-up area. The interaction has a clustered pattern with p-value less than 0.01. It indicated in the area with flat surface topographic has lower groundwater levels than others. There are several points who indicated the cone of depression in the built-up area with flat topographic. The geographically weighted regression model has high spatial variability and better results than the global regression model to assess groundwater level interaction with surface topographic.
Big data: definition, characteristics, life cycle, applications, and challenges
Authors: Basim Alwan Hiba , Ku-Mahamud Ku Ruhana
Published: June 2020

Any data set contains large volumes of information and complex data is called Big Data (BD). BD is unlike other traditional data sets, so it requires special processing to manage it. BD faces many challenges starting from data capture through to the final results. BD exists in many subject areas such as business, governments, sciences, healthcare and transport. Thus it touches peoples’ lives in many aspects. BD is considered as the most important topic and requires good understanding in order to be fully utilized. This paper presents the basic information of BD which includes its properties and applications. Descriptions and examples of BD and its categories are elaborated upon. The BD architectural establishment is presented followed by the conclusion of the importance of BD.
Dengue Outbreak Prediction Using an Improved Salp Swarm Algorithm
Authors: Amalina Mohd Rosli Khairunnisa , Mustaffa Zuriani , Yusof Yuhanis , Farhan Mohamad Mohsin Mohamad
Published: June 2020

Dengue disease is the most common type of disease caused by mosquitoes. It is reported that dengue fever was first recognized in Thailand and Philippines in 1950. According to World Health Organization (WHO), dengue is a viral disease that spread in public environment where the number of dengue cases reported enlarge within 5 years by 1 million from 2.2 million in 2010 to 3.2 million in 2015. Until today, numerous studies by researchers to improve the prediction of dengue fever disease based on Computational Intelligence (CI) methods have been reported. The research includes study using Swarm Intelligence (SI) algorithm. This research study proposed an improved Salp Swarm Algorithm (iSSA) for dengue outbreak prediction. The original SSA will be enhanced by enriching the exploration and exploitation process for the sake of improving the accuracy of dengue outbreak prediction. This will be done by inducing a mutation based on Levy Flight. Later, the iSSA algorithm will be realized on dengue disease dataset. The proposed iSSA will be compared against the original SSA and another CI method known as Grey Wolf Optimization (GWO). Two evaluation indicators known Root Mean Square Error (RMSE) and as Mean Absolute Error (MAE) are proposed in this research study to evaluate the prediction model where the smaller the value obtained, more accurate the prediction model. The result demonstrated that the proposed model produces a better result compare two the other results where the value of MAE and RMSE of the proposed model is smaller compare to other two model.
Students’ Continuance of Using E-Learning System: A Review of Conceptual Frameworks
Authors: Rahman N S A , Rosman A N , Sahabudin N A
Published: June 2020

This research presented a review of conceptual framework regarded to find the factors of students’ continued use of online learning system. The outcomes were reported according to a systematic review on the recent research articles (from 2013 until 2019) related with continued use of e-Learning system. From review of theoretical models and related theories we recommend to use Unified Theory of Acceptance and Use of Technology (UTAUT) to measure students’ intention to continued use of e-learning system. The discussion of this research obtained revealed that the most common factors influence students’ intention to continued use e-learning are performance expectancy, effort expectancy, social, self-efficacy, perceived usefulness and behavioral intention to continued use.
Improvement of tribological characteristics of rubbing surfaces as one of ways to increase energy efficiency of power plants
Authors: Karelina M Yu , Pydrin A V , Gaidar S M , Vorontsov A S , Qeblawi L Y
Published: June 2020

In this study, the team of authors solves the problem of increasing the energy efficiency of power plants by reducing losses while lowering the coefficient of friction. This problem is solved with the help of a multifunctional additive to lubricating oils, which are a surface-active substance (surfactant) capable of changing the friction conditions of contacting surfaces in a small amount when introduced into tribological units. The tests were carried out on a friction machine II5018 on a block-roller friction pair (the material of the roller is gray cast iron SCh20, the material of the block is steel 65). During the study, the moment and coefficient of friction were determined. A friction coefficient decrease of up to 50 % was obtained, which proves the effectiveness of the proposed compositions.
Analysis of thermophysical properties of asphalt mixtures
Authors: Zorin V A , Baurova N I , Kosenko E A
Published: June 2020

The article describes the main stages of experimental design of thermophysical properties of asphalt mixtures. Based on the results experimental studies, we have constructed graphs showing the dependence of the cooling time of the asphalt concrete mixture on environmental conditions and the method of thermal insulation of the asphalt concrete mixture during its transportation. Thermograms of experimental samples clearly show the effectiveness of various methods of thermal insulation of asphalt concrete mixes. The choice of a regression model characterizing the dependence of the cooling time of an asphalt concrete mix on variable factors is substantiated.
Effect of pressure boost on the diesel performance and gaseous emission with fuel spray pressure up to 3000 bar
Authors: Shatrov Mikhail G. , Dunin Andrey Y , Nguyen Thin Quynh
Published: June 2020

The study presents the results of a single-cylinder engine modeling that assesses the effect of turbochargers on diesel performance and gaseous emission with the fuel injection pressure up to 3000 bar. 3D modeling is performed in Fire ESE Diesel. The results show that indicator power, soot, HC increase, and BSFC, NOx decrease when using turbochargers. The boost pressure increases from 1 to 3.5 bar, the indicator power and BSFC vary tremendous, while the boost pressure increases from 3.5 to 4.5 bar, the indicator power, and BSFC change slowly. Indicator power grows by 15 %, BSFC reduces 16.6 %, NOx value goes down by 85 % and soot value goes up by 92.9 %, the maximum value of HC goes up by 51.6 % with a boost pressure of 4.5 bar and SOI at 17° BTDC. When the SOI falls, BSFC reduces and the maximum value of this reduction is 6.4 %, while indicator power increases by 5.6 % with the boost pressure of 3.5 bar. NOx value goes down by 70.3 % and soot value goes up by 88.6 % with the boost pressure of 4.5 bar. With the SOI of 5° BTDC, the turbocharging pressure from 2.5 to 4.5 bar, gaseous emissions meet the EURO V standard without the use of exhaust gas after-treatment systems.
Strain-rate-dependent model for the elastoplastic dynamic contact of sphere and plate
Authors: Jin Tengfei , Yin Xiaochun , Zhang Lin , Wang Hui , Yu Bo , Hao Qiming
Published: June 2020

A force-indentation contact model is presented for the dynamic contact loading of elastoplastic particle and plate to incorporate the material’s strain-rate-dependent plasticity, built theoretically from the well-known Hertz contact law and Hill’s solution for elastic and elastoplastic quasi-static contacts. A theoretical relation of the relative impact velocity and plastic strain rate is introduced to solve the model’s parameters. A Johnson–Cook strain rate dependence is included into the model to consider dynamic effects. We validate the model using finite element analysis and show that the model can accurately simulate the force-indentation relation. The impact responses of plate simulated by applying the model combined with a substructure technique are validated using finite element analysis and laboratory test. With the aid of the model, a significant decrease in contact pressure during fully plastic indentation and the independence of dynamic contact-loading path upon loading rate are observed.