bluuebunny/crossref_metadata_2025 huggingface dataset:
2D simulation of interaction between separation region and gasdynamic perturbation caused by rapid heat release in supersonic airflow
Authors: Saveliev A.S.
Published: January 2021

2D modeling of rapid local release of thermal energy (0.1 – 7 J/m) into the supersonic airflow (Mach numberM=2) was carried out in order to change the flow pattern around the wing model. It was shown that the results of numerical simulation of the process of a single instantaneous local heat release on the surface of the model are in good agreement with the experimentally obtained patterns of the flow around the wing model when energy was released using long spark discharge. The simulation of the process of local rapid energy deposition in a pulse-periodic mode was carried out and it was shown that, on the average over time, it is possible to significantly reduce the separation region size. In this case the calculated aerodynamic coefficients of the model change by several percent. It was found that the right choice value of frequency is important, since at an inappropriate value, the effect may be the opposite. It was shown that the stability of the repetition rate of local energy inputs is also important for the shift of the separation point downstream. The mechanisms of the effect of rapid local energy input on the separation region at relatively low and high values of thermal energy are discussed.
Estimation of gas-dynamic characteristics of supersonic plasma jets based on spectroscopy results
Authors: Pashchina A S , Chinnov V F , Efimov A V
Published: January 2021

A method for estimating the gas-dynamic characteristics of supersonic plasma jets based on the minimum number of plasma parameters (electron number density and temperature) that are easily measured by spectral diagnostic methods is considered. The course of the most important parameters characterizing the gas dynamics of the nonequilibrium plasma flow in the shock-wave region of a supersonic plasma jet created by a pulsed capillary discharge is revealed, and their values are estimated. A significant difference between the electron and gas temperatures was found in the vicinity of the central shock wave.
Analysis of Grounded Substrate Effects on Cold Atmospheric Plasma Jet Irradiation of Cellular and Animal models
Authors: Schweigert I. , Alexandrov A. , Zakrevsky D. , Gugin P. , Milakhina E. , Golubitskaya E. , Troitskaya O. , Biryukov M. , Koval O.
Published: January 2021

Plasma devices with cylindrical and plane geometries generating the nonthermal atmospheric plasma jets are used for the treatment of the cancer cells in vitro and in vivo. It is shown in the simulations and experiment that the grounded substrate placed under the bio target essentially increases the plasma treatment efficiency. Nevertheless the temperature control is needed to avoid the burns in a spot of contact of plasma jet with the mice skin. The measured and calculated local temperature increase with different regimes of plasma device operation is presented. The MTT and iCELLigence assays of the viability of cancer cells in vitro show the efficiency of plasma jet treatment and mice models in vivo demonstrate the safety regime for cold atmospheric pressure plasma irradiation.
Current-voltage characteristics of a discharge in a supersonic flow of ionized air in permanent magnets field
Authors: Baranov D.S. , Bityurin V.A. , Bocharov A.N. , Bychkov S.S. , Grushin V.A. , Kusmartseva E. V. , Tretyakova N.V. , Batura N.I. , Zhurkin N.G.
Published: January 2021

The work is devoted to the development of direct conversion devices of energy of high-enthalpy hypersonic gas flow into electrical energy. The experiments were carried out to study the electrical characteristics of the gap between two electrodes filled with weakly ionized plasma of the airflow at the wind tunnel with a magnetogasdynamic accelerator SMGDU. The voltages induced in the field of permanent magnets and the corresponding induction currents were measured with an ohmic load in the external circuit. The current-voltage characteristics of the discharge are constructed for the case of an additional supply of a current pulse from an external source to the interelectrode gap. The conductivity of the medium in the gas flow and the MHD interaction parameter were estimated. The results obtained can be used in the design of surface MHD generators for the autonomous production of electrical power on board of a hypersonic aircraft.
Selectivity of plasma actuators in a boundary layer transition control applications
Authors: Moralev I. , Popov I. , Selivonin I. , Ustinov M.
Published: January 2021

The paper describes the results of the study of broadband velocity pulsations, induced by dielectric barrier discharge plasma actuator in the 2D subsonic boundary layer, and their role in a boundary layer excitation. The origin of the velocity pulsations is the stochastic dynamics of microdischarges. The presented data include the parametric study of the disturbances power on the supply voltage characteristics and their structure. Also, the preliminary study of the role of the broadband disturbances in the Tollmien-Schlichting wave excitation was performed.
CFD analysis of pylon equipped by plasma module for combustion in supersonic airflow
Authors: Firsov A A , Dolgov E V , Kolosov N S , Yarantsev D A
Published: January 2021

Two new geometrical configurations of pylon equipped by plasma module for combustion in supersonic airflow were developed and discussed. This paper presents the results of three-dimensional CFD simulation of the flow around the pylon. The simulation was performed for two modifications of pylon and two possible geometries of set of three pylons. No fundamental difference was found between the two pylon geometries. It was shown that in one case of the installation of three pylons it provides continuous flow around the pylons, which should ensure stable operation of the plasma generator. In the second case of the arrangement of the pylons, the obtained flow structure promotes faster mixing of fuel with air; however, a significant separation zone is formed behind the pylons, which may impede the stable operation of the discharge.
Parameters of an electric discharge in a mixing layer of a supersonic air flow and an injected gas
Authors: Firsov A.A. , Efimov A.V. , Kolosov N.S. , Leonov S.B.
Published: January 2021

The data obtained by spectral measurements, high-speed video recording and the current-voltage characteristics acquisition allowed to estimate the parameters (Te, ne, σ) of the gas discharge plasma organized in a shear layer formed at injection of carbon-containing gases into supersonic air flow. Injection of ethylene (C2H4) into air imitates hydrocarbon fuel; injection of carbon dioxide (CO2) into the air imitates products of chemical reactions.
Acoustic radiation by a Hill vortex in viscous heat-conducting gas
Authors: Cherkasov D.Y. , Shugaev F.V.
Published: January 2021

Acoustic radiation by a Hill vortex has been studied on the basis of the Navier – Stokes equations. We used the expansion of unknown functions into power series of the initial vorticity which was assumed to be small. The Navier-Stokes equations were reduced to a parabolic system with constant coefficients for higher derivatives. The problem is set in such a manner. The vorticity is defined inside a sphere at t = 0. The initial density and the temperature are assumed to be constant throughout the whole space. The solution is represented as a power series whose coefficients are multiple integrals. They have been calculated with the aid of Korobov grids. The density oscillations have been investigated. The frequency spectra were studied at various distances from the vortex. The results may be useful for modelling decaying grid turbulence.
Hydrodynamic phenomena in optical discharges in liquids under self-focusing of periodic-pulse laser radiation
Authors: Lavrentyev S Yu , Solovyov N G , Shemyakin A N , Yakimov M Yu
Published: January 2021

Quasi-stationary flows under the effect of focused periodic pulse femtosecond laser radiation were generated and observed in liquid solvents: water, heavy water, alcohols, ketones, chloromethanes. The mechanism inducing directional flows appears to be directional collapse of the gas bubbles produced by multiphoton dissociation in a focused laser beam. Laser pulses of 450 fs length, up to 220 μJ pulse energy at repetition rates up to 10 kHz have induced stationary flows of liquid originated from the laser beam waist directed along or transversely to the beam axis. The streams along the beam axis were observed under low pulse power (10-20 μJ), provided precise lens adjustment. Lens displacement transversely to the beam axis led to splitting beam waist in two astigmatic foci. Both foci generate the streams along the beam axis. Counter directed streams have collided in the gap between foci, forming the flow spreading transversely to the laser beam. The increase of the pulse energy was followed by formation of the filament of self-focusing. Repeating cycles of focusing and defocusing along the filament produced several beam energy dissipation zones, each one generating separate streams along the beam axis. Colliding of the counter directed streams gave rise to complex flow pattern transversely and upward with respect to the beam axis.
Dielectric barrier discharge in radially converging gas flow generating two coaxial and opposite directed non-thermal plasma jets
Authors: Akishev Yu.S. , Petryakov A.V. , Trushkin N.I.
Published: January 2021

An original source of non-equilibrium low-temperature plasma jets based on a barrier discharge in a radially converging flow of atomic and molecular gases at atmospheric pressure was developed and created. The discharge electrode system consists of two parallel and coaxial quartz disks, in the geometric center of those two coaxial identical holes were made. On the outer side of each disk a metal foil in the form of a wide ring is glued coaxially to the holes. The gas flow is directed from the periphery of the disks to their center and exits normally to the disks surfaces through narrow holes. As a result, two coaxial and opposite directed plasma jets are formed, which are perpendicular to the disks. There are no analogs of the developed source in literature. The source has been tested for plasma treatment of dielectric yarns that are transported through holes in dielectric barriers and are constantly enveloped in plasma jets. The results show practical possibility of using the developed gas-discharge source for continuous “roll-to-roll” plasma treatment of polymer filaments with the aim to improve their hydrophilicity.
Study of the dependence of the structure and luminescence of the discharge channel in a discharge with a liquid cathode from the electrochemical properties of a liquid cathode
Authors: Chistolinov A.V. , Yakushin R.V. , Perfilieva A.V. , Sargsyan M.A. , Gadzhiev M.Kh. , Tyuftyaev A.S.
Published: January 2021

In the present work, the structure of the discharge channels glow of a discharge with a liquid cathode at different pH values of the solution at a given concentration of alkali metal (Na) ions in the solution is investigated by the methods of emission spectroscopy and high-speed photography. The dependence of the atomic sodium line intensity in the emission spectrum of the discharge plasma from the pH value of the solution is investigated. The dependence of the discharge channels filaments shape on the presence of sodium impurities in them is found. The spatial and temporal inhomogeneity of sodium luminescence in the emission spectrum of the discharge channel of a discharge with a liquid cathode at different pH values of the solution is studied. Its connection to the mechanism of sodium transfer into the gas phase is discussed.
Laser breakdown model in the absorption mode behind a light supported detonation wave
Authors: Kiseleva T.A. , Korotaeva T.A. , Yadrenkin M.A. , Yakovlev V.I.
Published: January 2021

The light supported detonation wave (LSDW) propagation with the laser radiation absorption in a narrow layer behind wave’s front is considered in the paper alternatively to the volumetric energy source model usually used for the energy deposition simulation [1-7]. The next laser plasma flow features were revealed in [8] by methods of numerical simulation:

1) laser plasma forms high-speed jet flow behind the LSDW front along the light beam propagation direction,

2) jet parameters are close to an isentropic flow mode at significant distances from the LSDW front, therefor can be determined with a good approximation using the unsteady pressure solution for the point explosion model with a kinematic x-t transformation. These features allow one to determine the plasma momentum value (in the direction of a laser beam) of the optical breakdown as an additional factor of effect on gas flow, first indicated in [9]. For an argon flow, we used a comparative analysis of the results of numerical simulations obtained both accounting the absorbed energy only and the breakdown plasma momentum additionally acquired at the absorption of radiation behind the LSDW front.

The experimental results of an optical discharge plasma in a subsonic argon flow are also presented. Pulse-periodic radiation with a frequency of 40 kHz and average power of 1.6 kW (peak power more than 30 kW) was generated by CO2-laser created in ITAM SB RAS. In order to obtain the LSDW mode by increasing a length of the breakdown plasma a focusing system f / d ≈ 9 was applied. A high-speed video camera with the exposure time of 1.0 μs, and the shooting speed of 200,000 frames / sec was used to record process. It has been established that the plasma dynamics has two successive stages: from the initial high-speed (of the order of 1 μs) propagation of the optical discharge to the subsequent lower-velocity gas-dynamic stage.
On the classification of the laminar-turbulent transition process using the methods of nonlinear dynamics: general analysis and the future
Authors: Evstigneev N M
Published: January 2021

The definition of a turbulent flow is still not mathematically defined. Different methods exists that provide different definitions resulting in different approaches and classifications of the laminar-turbulent transition as well as the fully developed turbulent flows. The paper includes the analysis of different stages of turbulence development, specific methods that are used in each stage and possible methods of unification of these methods based on the nonlinear-dynamical approach. Results are demonstrated for some characteristic fluid dynamics problems. Future highlights on the path to possible unification are discussed.
Fully implicit multiple graphics processing units’ schemes for hypersonic flows with lower upper symmetric Gauss-Seidel preconditioner on unstructured non-orthogonal grids
Authors: Bocharov A N , Evstigneev N M , Ryabkov O I
Published: January 2021

The paper discusses the simulation of the hypersonic flow problems on unstructured grids using fully implicit scheme and the analysis of the orthogonal corrections on the quality of heat fluxes on the surfaces of the bodies subject to hypersonic flow. The governing equations are the Navier-Stokes equations for viscous calorically perfect gas. Second order finite volume discretization is applied to the problem on arbitrary unstructured grids with implicit temporal treatment. The problem is solved using the Newton-Raphson method. Such methods require the solution of large linear systems with iterative solvers and require a preconditioning operator to converge. In this paper a well known Lower-Upper Symmetric Gauss Seidel (LU-SGS) preconditioner is applied. The new method is based on the tricky reordering for the factored Jacobi matrix that allows one to execute block triangular matrix solvers on GPUs in parallel without the loss of algebraic properties of the original non-factored operator. Good convergence properties are demonstrated for large scale problems of external aerodynamics with implicit Courant number around 1000 - 10000 for flows with Mach number around 13-25. The influence of the non-orthogonal corretions on the fluxes for highly scewed anisotropic grids is demonstrated at Mach numbers around 20. It is shown that the non-orthogonality corrections are of the second infinitesimal order compared to the effects of the shock fix influence on the heat fluxes on the body.
Non-stationary layered vector fields and their divergence functions
Authors: Burakhanov B M
Published: January 2021

This paper discusses the general properties of non-stationary layered vector fields and their functions of divergence. According to the classification of vector fields proposed in [1], layered vector fields are vortex vector fields that require two scalar functions to be defined. The main attention is paid to the study of a class of non-stationary layered vector fields that have the property of convergence to a stationary layered vector field. This means that these stationary layered vector fields can be considered as the result of the convergence process of non-stationary layered vector fields. It is shown that the condition for convergence of some non-stationary layered vector fields to a stationary layered vector field is that one of the two scalar functions that must be set to define a layered vector field belongs to the set of so–called scalar T-functions. T–functions are divided into two classes and the general properties of T–functions belonging to each of these classes are considered. Scalar characteristics of the mentioned non-stationary layered vector fields with properties of the Lyapunov function [2] are established.
Near-surface layer formation in the surface dielectric barrier discharge driven by negative voltage pulse
Authors: Soloviev V R
Published: January 2021

The reason of the near-surface layer formation in the Surface Dielectric Barrier Discharge driven by negative voltage pulse has been analysed numerically. According to calculations, the thickness of this layer is around 4μm in atmospheric pressure air; it is inversely proportional to gas density and does not depend on applied voltage value and dielectric parameters. The electric field value inside a layer depends on applied voltage and changes from 60 to 600kV/cm for negative voltage pulse amplitudes from 4.5 to 24kV.
The effect of the exposed electrode oxidation on the filamentation thresholds of a nanosecond DBD
Authors: Selivonin I. , Ding C. , Starikovskaia S. , Moralev I.
Published: January 2021

The paper presents the results of a study of the effect of an oxide film formed on the edge of an electrode on the filamentation threshold voltage of a surface nanosecond DBD. Since the oxidation of the discharge edge has a significant effect on the discharge operation mode and dissipated power, some changes in the filamentation thresholds should be observed. The presented data include the filamentation thresholds of a discharge on an aluminum electrode in synthetic air in the pressure range of 1-10 bar in the case of a new electrode and an electrode covered by an oxide layer. The studies were carried out for both positive and negative polarity of the supply voltage pulse at two pulse shapes with different voltage growth rates. The effect of pulse shape, as well as the effect of air humidity on the filamentation threshold, is discussed.
Emission spectrum analysis of an atmospheric electrode microwave discharge in argon flow and of a cold plasma jet on its base
Authors: Antipov S.N. , Sargsyan M.A. , Gadzhiev M.Kh.
Published: January 2021

The measurements and analysis of the emission spectra both of atmospheric-pressure electrode microwave discharge in argon flow and cold plasma jet induced by the discharge are conducted. We used experimental setup based on the previously developed multipurpose 2.45-Hz-plasmatron with the external portable discharge chamber (plasma torch) with the outlet of 2.5 cm in diameter and power of about several hundred watts. Discharge chamber has 6 rod-like electrodes which form a regular hexagon in a cross section of the torch. Discharge channels are formed between the ends of the electrodes and the inner wall of the chamber. Molecular bands of NO, OH, N2, NH and atomic lines of Ar were found in the spectrum of the discharge channels. Based on the analysis of the spectra, it was shown that the gas temperature in the discharge channel was about 1200 K. In the cold plasma jet spectrum, due to its weak luminescence, only the molecular lines OH and N2 were reliably observed.
MHD simulation of sawtooth events in meridional plane driven by various solar wind velocities
Authors: Gubanov E. V. , Likhachev A.P. , Medin S.A.
Published: January 2021

The meridional global MHD modeling of magnetosphere sawtooth events is performed for three values of the solar wind velocity: 200 km/s, 400 km/s and 800 km/s. The tooth cycle period of the open magnetic field specific flux decreases from 6.4 to 2.0 ks, respectively, while the oscillations amplitude changes inessentially. The tail magnetic field topology evolve through all the standard phases and events. In the distant tail the flapping current sheet is disturbed by the Alfven waves. In the dipole magnetic field domain the night-side attached vortices splitting and their subsequent shedding occur forming the Karman like vortex street. The vortex shedding period falls from 200 s to 110 s with the increase of the solar wind velocity. In the day-side shocked layer the vertically elongated thin magnetic island with the two neutral points is located. The magnetic island accounts for the deflection of the solar plasma inflow around the magnetosphere.
Study of cooling process of plasma jet flowing around a thin ablating graphite rod
Authors: Khromov M.A. , Kavyrshin D.I. , Chinnov V.F. , Sargsyan M.A.
Published: January 2021

We present results of spectroscopic measurement of electron temperature in submerged nitrogen and argon mixture plasma jet for cases of free flow and introduction of thin graphite rod into the jet. The observed cooling of plasma caused by rod introduction agrees with the calculated enthalpy decrease from graphite rod heating and ablation. In this experiment, a marker was used to create artificial optical inhomogeneities in the flow, which allowed us to determine flow velocity from the analysis of their movement. In this case, we aim to determine the degree of influence of rod introduction into the plasma on its parameters. Upon introduction into the plasma, the rod was heated and partially destroyed by the plasma flow, reducing its temperature by 8-20% depending on the flow rate of the plasma-forming gas. The observed plasma cooling was compared with the calculated decrease in enthalpy caused by the cost of heating and ablation of the rod material.
Investigation of LCAO approximation for diatomic molecules in Hartree-Fock method
Authors: Mitin A. V. , Bityurin V. A. , Bocharov A. N.
Published: January 2021

It was shown that the use of the conventional two-center LCAO approximation in the Hartree-Fock method results in non-equivalent description of the asymptotic properties of the total molecular wave function and MO’s in the directions of the united and separated atoms. This leads to a deviation of the Hartree-Fock potential curve calculated with using this approximation from that one obtained without it and which is growing with decreasing the internuclear separation. Additionally, the method has been developed for an investigation of the quality of the asymptotic behavior of the potential curves by analyzing their analytical properties. The direct comparison of the Hartree-Fock potential curves of CH and OH molecules obtained with and without LCAO approximation, as well an application of the proposed method for investigation of the analytical properties of them, display this shortcoming of the conventional two-center LCAO approximation.
Neutron Flux and Soft X-Radiation Created by Heterogeneous Plasmoid
Authors: Klimov A I , Belov N K , Tolkunov B N
Published: January 2021

Experimental results on registration of different radiations from a heterogeneous plasmoid (HP) created by pulsed-repetitive discharge in the experimental set up PVR are considered in this work. Intensive cold neutron flux, optical radiation and soft X-radiation (E<10 KeV) were measured in the HP. It was revealed that there is a high voltage threshold Ud>3.8 kV in the electric discharge for stable generation of intensive cold neutron flux.
Effect of pyrolysis temperature on the synthesis of high-quality MWCNTs by CVD method
Authors: Abdel Aziz Omar , Wafy Tamer Z. , Abdelhafiz Mahmoud , Elsayed Mohamed A.
Published: January 2021

Production of high-quality Multi-Walled Carbon Nano-Tubes (MWCNTs) is essential in some field, especially in medical and mechanical applications. This work illustrates the synthesis of high-quality (MWCNTs) by Injection Chemical Vapor Deposition (Inj-CVD) method using Ferrocene / Toluene solution as a carbon precursor and a catalyst. The effect of synthesis pyrolysis temperature, which has a pivot impact on the synthesis process, was investigated. The structure defects, impurities, thermal stability and sample morphology, as well as the mean diameters of the MWCNTs, were analyzed using Raman spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscope (SEM), respectively. The results revealed that a change in quality, mean diameter and purity were observed when the pyrolysis temperature varied between 700°C to 850°C. High-quality MWCNTs were observed by Raman spectroscopy at a pyrolysis temperature of 700°C with ID/IG = 0.2. While the outer and inner diameters were 25±6 nm and 7.8±1.5nm respectively, measured by Transmission Electron Microscope (TEM). The Inj-CVD shows an excellent control of the quality of the prepared MWCNTs by optimizing the synthesis temperature.
Synthesis and characterization of barium hexaferrite (BaFe12O19) nanoparticles from iron ore waste and their possible application in water treatment
Authors: Erfan Nehal A. , Abdel-Hameed Salwa A. M. , Mohammed Asma A.
Published: January 2021

In this work hard magnetic glass ceramics has been fabricated using Egyptian Bahariya oasis ore; which contains not less than 51% of its weight as pure iron. High energy planetary ball mill was used to convert the prepared magnetic sample into nanoparticles. Different mechanical milling times were applied to study its effect on the properties of the produced magnetic glass ceramic. Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray florescence analysis (XRF), differential thermal analysis (DTA), X-ray diffraction analysis (XRD), Raman spectroscopy and Vibrating sample magnetometer (VSM) analysis techniques were performed to characterize the prepared glass ceramic samples before and after exposing to mechanical milling process. XRD revealed crystallization of barium hexaferrite as major phase with average crystallite size ∼26 nm. Saturation magnetization Ms depicted 21.2 emu/g after 5 hours milling. The produces nanoparticles after 5 hours milling showed a good performance in removal of pollutants like methylene blue and Congo red from water by adsorption.
Catalytic oxidation over nanostructured heterogeneous process as an effective tool for environmental remediation
Authors: Thabet Rahma H. , Tony Maha A. , El Sherbiny Shakinaz A. , Ali I. A. , Fouad Mai K.
Published: January 2021

Industrialization has led to a severe deterioration in water quality. Textile industry is considered a huge consumer of water in Egypt; the result is generating large amounts of dye-containing wastewater that is essential to be treated before the final disposal. However, searching for efficient treatment is an important aspect for a sustainable environment. Advanced oxidation processes (AOPs) have been emerged as efficient techniques for industrial wastewater remediation. Among the AOPs, Fenton based reactions is considered a promising process for its simplicity in application and cost-efficient with high process efficiency. In this study, heterogeneous Fenton reaction using magnetite nanoparticles induced by ultraviolet radiation (UV) was applied as a green technology pathway for textile dyeing wastewater oxidation. Nanostructured magnetite was successfully obtained by co-precipitation technique that is used as the precursor of the Fenton’s reaction process. The heterogeneous iron (Fe2+/Fe3+) supported catalyst with hydrogen peroxide (H2O2) was used as a coupled Fenton and Fenton-like oxidation system for methylene blue dye removal in aqueous media. The obtained results investigated that the dye oxidation rate increases with decreasing pH to 3.0. However, increasing H2O2 and magnetite (Fe3O4) nanoparticles catalyst results in an increase in the dye oxidation rate and the optimum operating values were 80 and 1600 mg/L for Fe3O4 and H2O2, respectively. By optimizing the amount of reagents, process conditions as well, the results revealed that magnetite was considered an efficient Fenton-based catalyst for dye oxidation that is reached to 94% within 3 hr of oxidation time. Finally, magnetite catalyst could be easily recovered by magnetic separation to confirm the process sustainability.
Assessment of antioxidant resistance to thermal - oxidative degradation of stabilized polybutadiene binder
Authors: Elsaka Eslam , Elbasuney Sherif , Elbeih Ahmed , Mostafa Hosam E. , Awad Mahmoud E. , Elhedery Tarek M.
Published: January 2021

polybutadiene is the most common polymeric binder for composite solid propellants. This polymer suffers from oxidative degradation reactions on storing with deterioration in mechanical properties. Certain anti-oxidant materials can retard such reaction offering enhanced aging characteristics. In this study, two different primary antioxidants including phenol-based (AO2246) and amine-based (Flexzone 6H) were employed to stabilize polybutadiene polymer. Oxidation induction time (OIT) was evaluated using isothermal DSC. High OIT value means high resistance to oxidative degradation. The impact of anti-oxidant on mechanical properties was evaluated using shore A. Flexzone 6H significantly improved binder oxidative stability with an increase in OIT value by 20 folds with significant decrease in oxidation enthalpy. Flexzone 6H can offer enhanced resistance toward oxidative reactions; as it can act as efficient H atom donor to break down chain degradation reaction. Additionally, the three stabilized aromatic rings can capture free radicals. AO2246 enhanced the binder mechanical characteristics during aging at 80 0C using Shore A test. In the meantime, AO2246 could enhance the mechanical properties due to its integration into the polymeric matrix due to –OH functional groups. The two anti-oxidants demonstrated controversy effects. Whereas Flexzone 6H offered enhanced resistance to oxidative degradation; AO2246 offered enhanced mechanical properties.
A Study of the detonation wave shape inside confined explosive with a metallic copper liner
Authors: Elshenawy Tamer , Elbeih Ahmed , Zaki Mohamed G. , Hussein Ahmed K.
Published: January 2021

The behaviour of shock wave inside a shaped charge is so important that the detonation wave nature characterizes (determines) the degree of jet coherency at the liner interface. The detonation wave shape inside the shaped charge depends on the casing thickness, material, the liner material, geometry and the applied wave shaper geometry. In this paper, a series of numerical simulation models were performed to study the incident and reflected waves and to characterize the resulting shock wave front to evaluate its effect on the produced (generated) jet characteristics. The used code was Autodyn 3D based on non-linear dynamic analysis with jetting analysis model. Inert wave shapers (Lead, Aluminium and steel) and active ones (TNT and PETN) behaviour were studied. The liner type used in this study was copper with in which the apex angle of the liner cone was 40°. It was concluded that the wave front shape has an obvious influence on the characteristics of the jet formation and its properties such as mass of jet and velocities of its tip. Also, the bulk sound speed of the liner itself in addition to the collapse characteristics of the liner was discussed in this paper successfully.
The Potentials of Aluminium Nanoparticles: Novel High Energy Density Material for Underwater Explosions
Authors: Elbasuney Sherif , Gaber Zaky M. , Radwan c Mostafa , Bennaya Mohamed , Abdelkhalek Sherif M.
Published: January 2021

The destructive parameters of underwater explosives (i.e. shock wave energy, maximum pressure, and bubble radius) are limited to explosion heat; that is comparatively low. One approach for enhanced heat output can be accomplished by integrating reactive metal particles (i. e. Aluminium). However conventional aluminium particles (µm size) would contribute only with combustion gaseous products behind detonation wave front. Underwater, there is no oxygen for such contribution to take place. Furthermore, conventional Al particles could decrease the detonation velocity. So far, full exploitation of aluminium particles in underwater explosions has not been accomplished. Aluminium nanoparticles would combust more efficiently within detonation wave front, offering smaller critical diameter, high reaction rate, and high heat release rate. Consequently, Al nanoparticles could be ideal high energy density material for underwater explosion. Ship model with positive metacentric height, GMT = 4.7 cm for ship transverse stability, and GML = 19.3 for ship longitudinal stability was designed. Ship model offers large angle stability (heeling angles = 0-70 deg.). 2 g of explosive charge was detonated underneath the developed naval structure. Upon explosion, the acceleration of the naval structure was measured using shock accelerometer VC tri-axial, high frequency, 5000 ground acceleration, Dytran, Inc. While, Al particles (10 µm) offered an increase in mono-hull acceleration by 16 % compared to TNT; Al nanoparticles offered an acceleration increase by 49 %. This novel finding can be ascribed to the efficient combustion of Al nanoparticles within detonation wave front offering ideal detonation reaction with enhanced destructive effect.
Aluminium Nanoparticles: The Potentials of Metalized Explosives with Combined Destructive Effect (Combustion/Detonation)
Authors: Elbasuney Sherif , Gaber Zaky M. , Radwan Mostafa , Maraden Ahmed , Abdelkhalek Sherif M.
Published: January 2021

Even though, reactive metal particles can boost the energy density of explosive materials. Such particles will react behind the detonation wave front with decrease in detonation velocity and brisance (destructive effect). This study reports on the effective development of aluminium nanoparticles (NPS) of 100 nm particle size. Al NPs offered superior performance compared micron scale particles. Al NPs offered an increase in shock wave strength by 48 % compared with 17 % for micron scale particles. While micron-Al decreased the destructive effect of TNT by -6.5 %; Al NPs offered an increase in destructive effect by 21 %. The main outcome of this study is that Al NPs offered an enhanced detonation velocity of 6330 m/s compared with 5650 m/s for TNT. Additionally Al NPs offered decrease in TNT critical diameter from 40 mm to 20 mm. While conventional Al particles could act as desensitizer; Al NPs could act as sensitizer and could combust efficiently within detonation wave front. This study reports on the real development of metalized nano-composite explosives with combined destructive effect (combustion/detonation).
Physico chemical studies for water at Rosetta branch of river Nile, Egypt
Authors: Masoud M S , Ismail A M , kamel H M , El-Kholany A S , ElKasas A A M
Published: January 2021

This work was carried out to study the quality of water of Rosetta branch. Five sites were chosen for sampling during the period of January 2013 to December 2013. Physical parameters (Temperature, electrical conductivity (EC), turbidity and pH) and chemical parameters (concentration of Cl-, Ca+2, Mg+2, NH4+, SO4-2, NO2-, and some of trace metals, alkalinity, total hardness, Dissolved Oxygen(DO), Chemical Oxygen Demand(COD) and Biological Oxygen Demand(BOD) were discussed. These results were compared with the results of another study that were carried out at Rosita Branch at 2018. Statistical analysis of data was computed to show the correlation between some parameters through the whole sampling sites during the period of the study, using simple correlation coefficient.
Rain Transmission Losses Assessment in Arid Environment, Egypt: Numerical and Experimental Study
Authors: Bakheet Adel , Sefelnasr Ahmed , Saber Mohamed
Published: January 2021

In water-scarce regions, Transmission Losses Assessment from rainfall is required for the Numerical and Experimental Study of groundwater recharge. This Study is an attempt to assess Transmission Losses and the infiltration rate at Wadi El-Assiuti, Egypt, field infiltration experiments were conducted to measure the infiltration and porosity at the target area, such as using a double-ring infiltrometer. Determination and Quantify the infiltration rate of the soil is very vital as input parameters of the hydrological modeling, irrigation planning and other natural or man-made Processes. Steady state infiltration rates have been determined in selected sites of Wadi El-Assiuti. Accurate determination of infiltration rates is fundamental for trustworthy prediction of surface runoff and groundwater recharge. Double ring infiltrometer was used to measure infiltration rate at selected sites. An important part of the study was the accurate and consistent measurement of infiltration rates‥ The infiltration rate was calculated according to the installation and operating instruction for the double ring in ASTM 2003. Final infiltration rates were 18 cm h−1, for the first observation site, 24.2 cm h−1for the second site and 59 cm h−1for the third site. The analysis indicated that the soil for the three selected areas is sandy soil. Infiltration rates were taken at 0 to70 minutes of 10 minutes intervals. The infiltration rate at the third site is high compared to the other two selected sites. After performing the experiments, soil samples have been gathered and analyzed in the laboratory for porosity analysis. The results of this study can therefore be applied in the prediction of saturated hydraulic conductivity of the surface layers and groundwater recharge, and in developing or selecting the most efficient irrigation methods. The results from this work have been also involved in a numerical hydrological model to estimate the Transmission Losses form rainfall at Wadi El-Assiuti using Hydro-BEAM.
Synthesis and characterization of zinc-imidazolate coordination polymer and its use for photocatalytic degradation of methylene blue dye under visible light irradiation
Authors: Mohsen Mostafa , Naeem Ibrahim , Awaad Mohamed I. , Baraka Ahmad
Published: January 2021

Zinc-Imidazole coordination polymer (Zn-Im CP) was facilely synthesized by hydrothermal method from zinc acetate and imidazole as ligand. The structure of the synthesized Zn-Im CP was analyzed by using scanning electron microscopy (SEM), EDX, FTIR, and powder X-ray diffraction (PXRD). Surface area of Zn-Im CP was determined by BET analysis of N2 adsorption. The photocatalytic performance of Zn-Im CP using visible light irradiation source was investigated using UV–Vis spectrophotometer for the degradation of methylene blue. The pseudo first order reaction kinetic model was applied on the degradation data which gave the rate constant of 0.006 min−1. The results indicate that Zn-Im CP exhibits good photocatalytic performance for the photodegradation of methylene blue following indirect mechanism pathway.
Synthesis, characterization and application of analcime to control nitrate ions from the ground water samples from Wadi El-Assiuti – Egypt as a low-cost and locally available adsorbent
Authors: Abdelmoneim Ahmed A. , Abdul-Moneim Mohamed , Geies Ahmed A , Farghaly Seham O.
Published: January 2021

In this study, the sorption behavior of synthetic (Analcime) zeolites with respect to nitrate ions has been studied in order to consider its application to purity ground water. Analcime or also can be called analcite (“weak”) is a kind of grey, white or colorless tectosilicates minerals. It is hydrated sodium aluminum silicates which exist in cubic form in crystalline. Analcime was successively synthesized from kaolinite as a raw material using the fusion with NaOH method. The conditions of hydrothermal crystallization (zeolitization) were found to be at temperature of 170 C˚, and time span between 36 h and 72 h for kaoline with the molar composition of 6Na2O: 0.75Al2O3:30SiO2. 780H2O.The synthetic materials have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric (DTA/TGA) analysis and Surface area and porosity of synthesized analcime .The results indicate that the crystallization of analcime not affected by the hydrothermal reaction time. Also analcime was tested as adsorbents for the removal of nitrate ions from the ground water samples from Wadi El-Assiuti – Egypt .The adsorption capacities of nitrate ions by analcime, as a function of its concentration, were determined at room temperature by varying analcime concentration for each water samples. During the process, all the other parameters (pH and contact time) were kept constant with respect to the initial concentration of nitrate ions in the water samples. It was found analcime has good removal efficiency obtained at pH 6-7.6, adsorbent dosage 10-12 g/L, and contact time 60 min. The Langmuir constants model for NO3
− ion sorption on the adsorption isotherms is fitted well. The RL value in the present investigation was equal or less than one, indicating that the adsorption of NO3
−ion by analcime is favorable.
Thermodynamic Analysis for Tracking the Effect of the Egyptian Zirconium Silicate on the slag properties of low hydrogen Welding Electrodes
Authors: AbdElkarim A , Abd El Aziz H M , Mohrez Waleed A , Mashaal H
Published: January 2021

One of the most common types of welding electrodes, used in welding processes; are the low hydrogen electrode classification; E 7018. This electrode is applied for fabrication most carbon steel alloys, where it used for welding plate works of ships, equipment, tanks, boilers and pressure vessels, steel structures of buildings, bridges as well. One of the most common drawbacks resulting of using of this welding electrode is the difficulty of removing the slag between the deposited passes, which consumes time and money and hence decreasing the quality of welding process also one of the most drawbacks of this type of welding electrode is the rabid burning of coating flux at elevated amperes increase.

This study aimed to suggest rooted solution for these two problems by adding zirconium silicate to the flux recipe. Different percentages of Egyptian zirconium silicate were added to the coating flux recipes of type E7018 where the changes at both weldability and slag removing between deposited passes were noticed at different amperes. By using HSc simulation program of the thermodynamics data and expected phases in slag were studied. Microstructure samples of weld metal were imaged and analyzed, basicity index was calculated, XRF chemical analysis for all slag different samples, were determined. The study concluded that adding 5% of the Egyptian zirconium silicate to the flux clearly improved; the welding properties as well as the ease of slag removal.
Bioleaching of uranium from el-sella ore material using epicoccum nigrum
Authors: Elsayad Azhar M , Hussien Shimaa S , Mahfouz Mohamed G , El Mougith Abdou A , Hassanien Wesam A
Published: January 2021

Uranium (U) is one of the strategic elements and essential for many applications as a fuel in nuclear power plants and nuclear weapons. Bioleaching of uranium was carried out with Epicoccum nigrum isolated from El-Sella ore material. El-Sella area is located in the southern eastern desert of Egypt. The maximum bioleaching of U(VI) was found to be 76.6 % at these optimum conditions: 9 days incubation period, 0.5% pulp density, 30 °C incubation temperature at shaking speed 175 rpm. Glucose and NH4Cl were considered the best carbon and nitrogen sources for fungal growth. E. nigrum exhibits good potential in generating varieties of organic acids which effective for bioleaching of uranium. It produced 112.3 and 23.5 µg/ml from gallic and ellagic acids in the culture filtrate under the optimum conditions. This work addresses the area of beneficiation of the used mineral to solubilize U(VI) through the biotechnological route in Egypt, where the bioleaching method is more effective than the chemical one using organic acids.
Commercial approach for highly pure thorium from Egyptian monazite mineral acid process
Authors: Abd El Fatah A I L
Published: January 2021

Thorium has a special interest in the future nuclear energy as a fuel especially the breeder reactors. The present research has been fulfilled throughout successive research schedule manner on separation and purification of thorium from Egyptian beach monazite mineral after its acid digestion. Monazite mineral was digested with sulfuric acid 96% at 220°C for 2.5h and dissolute with ice water (1:15), the clear solution precipitated with ammonia solution 16.5% at pH 1to produce thorium pyrophosphate with 45% thorium content in case of ideal optimized whole process. The purification was carried out after the caustafication and leaching with hydrochloric acid followed by the addition of oxalic acid at pH 0.3-0.4 to produce thorium oxalate with 91.68 % purity. Thorium oxalate was transformed to oxide by caustafication then washed and separated and dissolute by hydrochloric acid. Highly pure thorium salt was attained with the addition of thiosulphate salt on the produced faint chloride solution under 0.1 to maximum 0.5 phosphate content to produce 99% purity.
Bio-sorption of uranium by saragassum detifolium from the trachytic sills of Wadi El Atshan area, central eastern desert, Egypt
Authors: Gad N SH , Farag N M
Published: January 2021

In wadi El Atshan area, Central Eastern Desert of Egypt, the main rock types exposed in that area are the older granites, Hammamat sedimentary rocks, younger granites, trachytic sills and dikes. The Field studies and radiometric survey indicate that the trachytic sills are the main rock type in the investigated area which contain secondary uranium minerals. Sargassum detifolium is used to capture uranium from the trachytic sills. The analysis indicates that this alga absorbs the uranium content by 100% in two samples where happened in the other samples as well as, it changes the chemical composition of some minerals content, while some elements changed while other elements are decreased, Sargassum detifolium has the ability to biosorbe uranium content about 75% as in uranotile mineral {CaU2 (SiO4)2(OH)6.3H2O}.
The effect of natural rubber on physical and mechanical properties of rubber seal for LPG tube valve
Authors: Handayani H , Ramadhan A , Cifriadi A , Kinasih N A , Falaah A F , Maspanger D R
Published: January 2021

The price of natural rubber (NR) continues to decline. In early January 2020 the price of Standard Indonesian Rubber (SIR) 20 was around 1.83 US$/kg and in May 2020 dropped to 1.09 US$/kg. Under this condition, NR downstream program becomes a necessity to increase domestic consumption of NR so that the sustainable rubber industry can be achieved. One prospective product and can be substituted using NR is the rubber seal for Liquified Petroleum Gas (LPG) tube valve. Based on the rubber seal quality requirements in Standar Nasional Indonesia (SNI) 7655: 2010, the rubber raw material should use rubber which is resistant to n-pentane. Nitrile Butadiene Rubber (NBR) synthetic rubber is suitable, meanwhile NR is not resistant to n-pentane so it is not suitable to produce rubber seal for LPG tube valve. Hence, this research studied the effect of NR on physical and mechanical properties of rubber seal compared to NBR compound. The results showed that NR improved elastic properties such as tensile strength, elongation at break and compression set, but decreased the resistance to n-pentane. Mixing NBR and NR with appropriate compositions can produce a better rubber seal for LPG tube valve.