Advances and Trends in Physical Science Research Vol. 2

An Investigation of the SAR Distribution in Bone Marrow with Possible Non-Thermal Effects

2021-07-22T03:31:34+00:00

The power absorption due to EMF radiation is calculated, in bone and bone marrow. The EMF employed in various communication and technological applications indicate undeniable effect on humans both as public and occupational environments. These EMF effects arouse from electronic devices such as, cellular phones and their networks, wi-fi routers, microwave transmitters, antennae, etc. besides the upcoming 5G generation and their extended applications. EMF exposure effects are estimated by either animal experimentation or phantom model assessments. Moreover computer modelling, either stochastic or deterministic, besides epidemiological studies are taken into account as well. A deterministic mathematical model is constructed and applied, using the reported frequency dependent electromagnetic properties, for bone and bone marrow. The specific absorption rate (SAR), in both anatomic structures, is computed according to the present mathematical model, is represented spatially in the bone-marrow-bone layers under study. The effect of exposure to electric field of strengths ranging from 1V/m to 1kV/m is investigated for a wide frequency spectrum in each layer of the proposed model. The frequency dependence of the SAR, through these layers, is illustrated for frequencies ranging from 1kHz to1GHz. The thermal and non-thermal power densities are calculated for an extended frequency range from (10MHz-100GHz).The present results are in agreement with international safety standards for applied field strengths of maximum value; 10V/m for bone and 100V/m for bone marrow. Furthermore, the present model shows that oblique incidence results in higher SAR values than with normal incidence, highly evident for low frequency, especially for the frequency 1kHz. Higher absorption rates are exhibited by frequencies around 10MHz than those exhibited by frequencies in the range 1GHz to10GHz. The model, developed by this study, provides a possibility for establishment of some features or changes in the assessed biological parameters, which couldn’t be established by other methods applied. The author suggests introducing standardization for the non-thermal power and giving its assessment considerable attention by the international organizations.

Aim: Deterministic evaluation of the microwave power density distribution and absorption, in long bone and bone marrow, due to far field exposure.

Study Design: A mathematical model is constructed and applied to a bone –bone marrow-bone section to simulate EMF propagation and hence absorption in each layer.

Place and Duration of Study: Department of Engineering Math. And Physics Dept., Fac. Of Engineering, Cairo University.

Methodology: The author employs a bone-marrow-bone model to investigate the effect of incident EMF. The equations governing the total electric and magnetic field distributions in each layer are deduced, considering its biological electromagnetic properties. The model is simulated by a computer program using Maple V. The computed values of real and imaginary components of power density in bone and bone marrow are graphically represented versus frequency. The exposure to electric field of strength ranging from 1V/m to 1kV/m is investigated using the proposed method. The frequency dependence of the power density, both dissipated and stored, through the bone-marrow-bone layers is illustrated for a frequency range of 1kHz-10GHz.

Results: Electromagnetic radiation of 1MHz-10MHz induce absorbed power within the safety limits for all applied field strengths. The 1GHz incident radiation induces SAR values higher than permissible ranges for field strengths above 400V/m whereas the same occurs for a low frequency range at 100V/m. Moreover, the present results are in agreement with international safety standards for applied filed strengths till 10V/m for bone and till 100V/m for bone marrow, covering the applied frequencies (1 kHz -1 GHz). Except for exposure to electric field of strength higher than 100V/m, the SAR acquired by the bone marrow is within the safety levels. These results also show that the non-thermal power densities are more effective for the UHF range 100MHz-100GHz.

Conclusion: The results obtained are in agreement with international safety standards for filed strengths of maximum value 10V/m for bone and 100V/m for bone marrow. Oblique incidence results in higher SAR values than normal incidence, especially for low frequency (1kHz). Non-thermal effects should be given further consideration especially for UHF ranges.

Quiet Time Variation of Ionosphere Parameters near Equator

2021-07-22T03:39:23+00:00

In recent, ionosphere has been intensively investigated by analyzing data variability and or improving existing models for now casting and or forecasting reasons. Therefore, the investigation of f2 layer critical frequency (fof2) parameter by means of the 2012 version of iri (international reference ionosphere) model and tiegcm (thermosphere ionosphere electrodynamics general circulation model) is required. The present study appreciates the estimation of TIEGCM (Thermosphere Ionosphere Electrodynamics General Circulation Model) and that of the 2012 version of IRI in African Equatorial Ionisation Anomaly (EIA) region through the diurnal variation of F2 layer critical frequency (foF2). The comparison made between data and theoretical values carried out from TIEGCM and IRI-2012 during solar cycle minimum and maximum phases and under quiet time condition over seasons. Data concern solar cycle 22 foF2 data of Ouagadougou station (Lat: 12.4° N; Long: 358.5°E, dip: 1.43°N for 2013) provided by Télécom Bretagne. Quiet time condition is determined by Aa inferior or equal to 20 nT and solar cycle maximum, and minimum phases correspond to sunspot number Rz superior to 100 and Rz inferior to 20, respectively. Seasons are estimated by considering December as winter month, March as spring month, June as summer month and September as autumn month. Models predictions are better during solar maximum than during solar minimum and strongly dependent on pre-sunrise and post-sunset periods. The seasonal Hourly quiet time foF2 is given by the arithmetic mean values of the five quietest day hourly values. Data profiles show noon bite out a profile with more and less pronounced morning or afternoon peak in equinox and that during solar maximum and that also in solar minimum except during solstice where the profile fairly is dome or plateau. During solar minimum, both models present a more or less pronounced afternoon peak with more or less deep trough between 1000 LT and 1400 LT. During solar maximum, in general, TIEGCM shows afternoon peak and IRI-2012 present plateau profile. This result exhibits the non-well estimation of the dynamic process of this region. Model accuracy is highlighted by the Mean Relative Error (MRE) values. These values show a better prediction for IRI-2012 except in September for both solar cycle phases involved. The non-good prediction of TIEGCM is observed in December during solar minimum and in June during solar maximum. This study shows that running IRI model enables to show that foF2 time variations present “reversed profiles” on minimum and “plateau profile” on maximum solar cycle phases. It also shows winter anomaly on foF2 profiles. These different conclusions have been previously found by other authors. This work also reports winter anomaly on foF2 parameter. The closed link between foF2 and TEC time variations is carried out. (Winter anomaly on TEC). The study shows Total electron contents effects on critical frequency of radio waves in the ionosphere layer.

Classical Mechanics from Stochastic Quantum Dynamics

2021-07-22T03:42:31+00:00

The present study deals with the corresponding stochastic Schrödinger equation (SSE) leading to the quantum-to-classical transition. This work shows that the stochastic generalisation of the quantum hydrodynamic analogy (QHA) has its corresponding SSE. The SSE owns an imaginary random noise that has a finite correlation distance so that when the physical length of the problem is much smaller than it, the SSE converges to the standard Schrödinger equation. The model derives the correlation length of the environmental noise, leaving the quantum potential energy of fluctuations finite, and shows that in non-linear (weakly bounded) systems, the term responsible of the non-local interaction in the SSE may have a finite range of efficacy maintaining its non-local effect on a finite distance. A non-linear SSE that describes the related large-scale classical dynamics is derived. The work also shows that at the edge between the quantum and the classical regime the SSE can lead to the semi-empirical Gross-Pitaevskii equation. The SSE can be helpful in describing at larger extent open quantum systems where the environmental fluctuations and the classical effects are both relevant.

Study on the Doppler Method to Detect Metal Fault

2021-07-22T03:46:11+00:00

The study deals with the interaction of ultrasound with metals discovered an unusual phenomenon. Microwave sensor indicates fluctuations of electric surface conductivity when exposed to elastic ultrasonic vibrations in metal objects. The defective area is by a content of microdefects of the type "the mouth of the cracks". They are known as the field of "acoustic activity" the method of Acoustic Emission (AE). The high coefficient of phase modulation of the reflected field allows you to indicate the Doppler signal is useful for 6-30 dB over the noise from a distance of 70-180 mm. The phenomenon is called "of Gorbunov effect". It has been successfully used as remote non-destructive testing method is ultrasonic methods of flaw detection, acoustic emission. A semiconductor detector responds to the amount of incident and reflected waves, registering the change in reflection coefficient. When injected into the area of the surface that differ in conductivity from the previous one can identify cracks the size of a quarter wavelength. It has been successfully used as remote non-destructive testing method that replaces the ultrasonic methods of flaw detection, acoustic emission. While testing a fragment of the steam-pipe destroyed during operation due to flooding, our device allowed to indicate these defects when the external surface of the steam pipe is excited by ultrasound. The microwave sensor at this time irradiated the outside surface of the steam. Rrevealing that the new device is able to reconsider the defectoscopy of the inne-surface of the steam pipe by chemical etching method of the inner-surface with scrutinizing by a contrast agent, a microscope, an x-ray flaw detector.

Another version of the test of the new device relates to the indication of the quality of zirconium tubes (used for heat Emitting Elements (TVEL) in thermal nuclear power plants). Result revealed that the manufactured tubes should be rejected due to the appearance of "punctures", "sticking", scratches, micro-cracks. All these defects can be determined by optical methods using special microscopes with electronic video recording, software. The time taken for this study takes up to ten minutes. The device, reveals the defects in 2-3 seconds.

Research work on the new device continues. The new results are significantly different (in a positive way) from the results of ultrasonic flaw detection, acoustic emission method, which use contact sensors, immersion lubrication. Noticing the contact of the generators of the ultrasound in the new device to the laser generators will let you create a fully remote device.

Stochastically-Induced Quantum-to-Classical Transition: The Lindemann Relation, Maximum Density at the He Lambda Point and Water-Ice Transition

2021-07-22T03:50:10+00:00

In the present paper, by using the quantum stochastic hydrodynamic analogy (SQHA), the transition between gas, liquid and solid phases, made of structureless particles, have been analyzed. The interest for the quantum hydrodynamic analogy (QHA) has been recently growing by its strict relation with the Schrödinger mechanics. The SQHA shows that the quantum behaviour is maintained on a distance shorter than the theory-defined quantum correlation length (lc). When the physical length of the problem is larger than lc, the model shows that the quantum (potential) interactions may have a finite range of interaction maintaining the non-local behaviour on a finite distance “quantum non-locality length” lq (with lq >lc ). The present work shows the realization of “classical” phases (gas and van der Waals liquids), when the mean molecular distance is larger than the quantum non-locality length lq. On the other hand, when the mean molecular distance becomes smaller than lq or than lc phases transitions such as to solid crystal or to superfluid appear, respectively. The model shows that the quantum character of the matter emerges as a consequence of the random noise suppression generated by the quantum potential below the induced noise correlation length. The model explains the Lindemann empirical law about the mean square deviation of atoms from the equilibrium position at melting point of crystal, and shows a connection between the maximum density at the He lambda point and that one at the water-ice solidification point. The SQHA shows that both the linearity of the particle interaction and the reduction of amplitude of stochastic fluctuations elicited the emergence of quantum behavior. The SQHA model also shows that the nonlinear behavior of physical forces, other than to play an important role in the establishing of thermodynamic equilibrium, is a necessary condition to pass from the quantum to the classical phases and that fluctuation alone are not sufficient.

A Simulation Study of Artificial Heating of the Ionosphere by Powerful High Frequency Radio Waves

2021-07-22T03:55:27+00:00

Results of numerical modeling of the behavior of the F-layer ionospheric plasma during the periods of action of powerful high frequency radio waves, utilized for artificial heating experiments and pumped into the ionosphere by ground-based ionospheric heaters, are presented and discussed. For obtaining the presented simulation results, two distinct mathematical models were applied. The first mathematical model is based on a numerical solution of the system of transport equations for ionospheric plasma. This mathematical model allows us to simulate large-scale disturbances of the spatial structure of the F-region ionosphere, caused by the absorbed energy of powerful high frequency radio waves. The second mathematical model is based on a numerical solution of the system of kinetic equations for ion and electron gases in the ionosphere. The latter mathematical model allows us to investigate numerically kinetic processes in ionospheric plasma, in particular, the behavior of magnetic field aligned super-small-scale irregularities in the concentration of charged particles. Moreover, this model has allowed us to establish new details of the mechanism responsible for artificial heating of ionospheric plasma by powerful high frequency radio waves, pumped into the ionosphere by ground-based ionospheric heaters. These new details of the heating mechanism will be presented and discussed in this study.

The results indicated that the presence of a standing high-power HF radio wave ought to influence significantly on the behavior of the bulk flow velocities of electrons and positively charged ions. At the levels of the loops of the wave, the vectors of the bulk flow velocities of the positive ions and electrons rotate with the frequency equal to the frequency of the disturbing HF radio wave. It turned out that considerable differences between modules of bulk flow velocities of electrons and positive ions take place at the levels of the wave’s loops, whereas, mentioned velocities are equal and negligible at the levels of the nodal points. As a consequence, intensive heating of the F-layer ionospheric plasma ought to arise at the levels of the loops of a wave. On the contrary, at the levels of the nodal points, the ionospheric plasma ought to stay undisturbed. The present study, revealed new details of the mechanism responsible for artificial heating of ionospheric plasma by powerful HF radio waves, pumped into the ionosphere by ground-based ionospheric heaters, have been submitted.

Paleoenvironmental Analysis and Its Significance in Sedimentology: Case Study of the Conglomerate Facies of the Awi Formation, Calabar Flank, Southeast Nigeria

2021-07-22T04:00:45+00:00

Pebble morphometry of unbroken quartz pebbles collected from the basal section of Awi Formation exposed around Ewen area, southeastern Nigeria was studied for paleoenvironmental reconstruction. Paleoenvironmental analysis refers to the study or use of ancient geological materials (rocks) to infer the depositional environment or setting within which they were deposited. Pebble morphometric analysis has aided the determination of paleoenvironment during the deposition of Awi Formation. The depositional processes responsible for shaping the pebbles and the environment that prevailed during past geological times was characterised. This involved the measurement of the three orthogonal axes (long, intermediate and short), determination of their corresponding roundness, flatness indices and elongation indices for no less than 200 pebbles. The pebbles were selected from 20 points across four exposed sections of the Awi Formation around Ewen village. The roundness was determined using the standard roundness chart. The results show that the pebbles are sub-rounded to sub-angular and predominantly compact-bladed. The mean values for the following morphometric parameters: Flatness index, elongation ratio, maximum projection sphericity index and oblate-prolate (OP) index are 0.57, 0.78, 0.74 and 15.65 respectively. These values are in agreement with those of modern fluvial pebbles. This result was integrated with the deductions from bivariate plots of roundness against elongation ratio and sphericity against OP index, and they all inferred the deposition of the conglomeratic sandstones in a fluvial setting with subordinate transitional setting. Fluviatile process with some overlapping littoral influence has been shown to be responsible for the variation in clast morphology of the paraconglomerates (matrix-supported) of Awi Formation. Integrating all observations viz; the sediment stratification and grading style (fining upwards successions) and the dominant unidirectional nature of the crudely imbricate pebbles, a typical fluvial setting is inferred. It is possible that the jointing, faulting, sheeting and/or exfoliation of the rocks of the Oban Massif, which is believed to be the principal source of the sediments (provenance), also accounts for the abundance of vein quartz in the area which was eventually adapted for this study. Within sedimentary settings as this one with paraconglomerates associated with high energy flux during deposition and other typical channel lag deposits are locations of good economic deposits (placer deposits) and in some cases hydrocarbon accumulation. Therefore, besides the significance for pebble morphometry in deciphering paleoenvironments, it also gives clues for potential sites of ore bodies and/or characteristics of some targets for hydrocarbon pools. There are obviously several methods for paleoenvironmental reconstruction using sediments as earlier mentioned, grain morphology is one. However, care must be taken when reconstructing paleoenvironment because the shape of grains is a result of so many other factors and for effective utilisation, a careful study and integration of all other parameters are recommended.

Cosmic Vacuum Energy Determining the Space-Time Geometry of the Empty Universe

2021-07-22T04:06:18+00:00

Different from energies constituted by baryons or photons both of which are expressed as energies per particle, vacuum energy by its nature represents a ”volume energy”, i.e. an energy represented by the sheer space volume, however, not simply reacting to the temporal change of this space volume, but rather in a non-evident way which we here try to ﬁx using thermodynamic principles. Vacuum energy is interpreted as a phenomenon of a polarization of empty space by real cosmic matter with the consequence that the prevailing vacuum energy should depend on the cosmic matter density. We try to interpret vacuum energy as a form of a heat capacity of cosmic volumes and study by the use of thermodynamical principles how the heat content of cosmic volumes should change with the change of the volumes themselves. In the present days of modern cosmology, it is assumed that the main ingredient to cosmic energy presently is vacuum energy with an energy density ϵ that is constant over the cosmic evolution. This paper shows that this assumption of constant vacuum energy density is unphysical, since it conﬂicts with the requirements of cosmic thermodynamics. The study starts from the total vacuum energy including the negatively valued gravitational binding energy and shows that cosmic thermodynamics then requires the cosmic vacuum energy density which can only vary with cosmic scale R = R(t) according to ϵ with only two values of ν being allowed, namely ν 1 = 2 and ν 2 vac ∼ R = 5/2. The study then discusses these two remaining solutions and ﬁnd, when requiring a universe with a constant total energy, that the only allowed power index is ν = 2. The consequences of this scaling of ϵ are discussed and the results for a cosmic scale evolution of a quasi-empty universe are presented.

Application of Xylopia aethiopica Seed Extract as Aluminium Alloy Corrosion Inhibitor in 0.75 M KOH Alkaline Solution

2021-07-22T04:09:39+00:00

Corrosion phenomena, control and prevention are unavoidable scientific issues that should be addressed due to increase of technological development. Aluminium (Al) is one of the most abundant elements found in the earth’s crust. The applications site of Al makes it to yield corrosion attack despite its corrosion resistance. The aim of alloying is to enhance the desired properties possessed by the Al. Plant extracts are rich source of naturally synthesised chemical compounds that can be extracted by simple procedure. The present study investigated the corrosion inhibition of Al alloy in 0.75 M KOH solution at room temperature using Xylopia aethiopica seed extract. The gravimetric technique was employed in the study. It was revealed that the presence of the spice extract in the test solution retards the corrosion rate. The calculated inhibition efficiency from the inhibitor surface coverage was observed to increase linearly with the inhibitor concentration. The consideration of the Langmuir adsorption isotherm indicated that the mechanism of adsorption is Physisorption. Temkin isotherm models explained that there were lateral attractions of the inhibitor molecules on the Al alloy surface. Flory-Huggins isotherm model confirms that there is bulky displacement of water molecules on the metal surface due to the presence of the inhibitor molecules. This depicts that the spice constituents clustered on the Al alloy surface preventing contact with the corrosive environment.

Degradation Monitoring of Hindered Amine Light Stabilizer Doped Polymers

2021-07-22T04:13:07+00:00

Polycarbonate (PC) is the most widely used aromatic polymer in various industrial applications. It is a condensation polymer in which benzene rings plus quaternary carbon atoms form bulky stiff molecules that promote rigidity and strength. The bulky chains crystallize with great difficulty, so the polymer is normally amorphous with excellent characteristics such as optical clarity, heat stability and mechanical resistance. The fluorescence and fluorescence excitation spectra of pure and doped PC depending on hindered-amine light stabilizers (HALS: Tinuvin 770 and Tinuvin 123) concentration and different processing conditions have been studied. Non-processed PC has no emission band in the visible range but processed PC with additives show visible fluorescence bands between 400–470 nm. It suggested that PC undergoes a kind of degradation process which lead to the fluorescence emission caused by the transitions from the new distortion-related localized states (defect states) created by processing and the additives. Such defects lead also to the emergence of a new band in the excitation and emission spectra at lower energies, where the symmetry of the bands break near. The intensity of these bands drastically depends on the sample treatment where the luminescence intensity quantitatively characterizes the concentration of defect radicals. An increase in screw speed resulted in an increase in specific mechanical energy (SME), higher SME led to a remarkable macromolecular degradation. The fluorescence spectroscopy of pure and doped polycarbonate (PC) depending on hindered-amine light stabilizers (HALS: Tinuvin 770 and Tinuvin 123) concentration and different processing conditions have been shown that pure non-processed PC has no emission band in the visible range but have an absorption band at 290 nm. Processing under excessive conditions is most likely to produce chains and general degradation which leads to a fluorescence emission. Processed PC with additives shows visible fluorescence bands between 400–470 nm. The intensity of these bands drastically depends on the sample treatment where the luminescence intensity quantitatively characterizes the concentration of defect radicals. PC becomes considerably yellow discolored with higher concentration of Tinuvin 770 or Tinuvin 123 and the PC gets more brittle (higher degradation grade).

Superluminal Motion of Free Spin-half Particles in a Fiber Bundle Formalism

2021-07-22T04:18:48+00:00

The hypothesis of the spin of an electron, leading to its angular momentum, is no longer an open question, in science. Experimental evidence like the hydrogen ﬁne structure and the Stern-Gerlach experiment in the 1920s and, recently, Nuclear Magnetic Resonance (NMR) have for long paved the way to deﬁnitely end this debate. Equipped with this mathematical machinery potent enough to handle the theories which are of interest to us, the expectation value of the overall relative linear velocity component of a fermion ﬁeld was investigated in a previous paper, found quantized, and exceeding the speed of light. In the present article, we aim to review and describe this result in the framework of a ﬁber bundle theory. Using a method developed in the 1980s by Zimmer for Dynamical-System theory, we explicate the feasibility of the superluminal free electron and neutrino result in bundle language.

Characterisation of Worst Month Statistics for Satellite-Earth Links Performance in Tropical Locations

2021-07-22T04:35:22+00:00

The study presents the results of experimental data showing seasonal variability of rainfall intensities at two locations in Nigeria. The increasing development in satellite technology has brought about several novel mobile satellite services and applications. Consequently, there is a pressing demand for seamless data transfer and accessibility to satellite-earth microwave links in SHF/EHF frequency bands. Mobile platforms available via satellite include e-defence, Tele-banking, Skype, e-learning and so on. Consumers continue to press for ubiquitous coverage, internet traffic by-pass, scalability and improved quality of service of communication systems. However, rain has been the major degradation parameter for the availability of satellite signals especially at frequencies greater than 10 GHz. This paper presents some statistical analysis of rainfall in two tropical locations in Nigeria – Akure (7°17’N, 5°18’E, 358 m) in the Southwest, and Jos Plateau (9°57’N, 8°58’E, 1192 m) in the north central. Rainfall intensities of one-minute integration time were measured for 19 months (June 2013 to December 2014). The degrading effect of rainfall intensities was highlighted in the statistics of the worst month and monthly variations in rain rates along Ku-band signal paths in the study locations. Predicted results showed that rain induced attenuation values above 30 dB occurred during the worst months, while clear sky values are below 2 dB. The worst month statistics obtained were largely different from those proposed by the ITU. Thus, for optimum link budgeting, the modified values of Q and ß should be adapted in these regions. The worst month statistics derived would serve as an essential planning tool for the system link designer for fade analysis and site diversity implementation; and eventually, result in better availability of radio-communication systems in the region. The results will facilitate improved radio-communication planning in the region. More investigation on beacon measurements of rain-induced attenuation is required to corroborate these results. The paper has revealed crucial considerations that affect the quality objectives of telecommunication systems. The results show that AY and AWM can be safely estimated from measured data of one minute integration time, and modelled with ITU-R recommended values. However, it is recommended that the worst-month design criteria of 178 mm/h and 150 mm/h for Akure and Jos, be considered as the actual design goal. Also, the relationship between the worst-month and average year has been given by β and Q1 parameters, as 0.372 and 1.060 for Akure, and 0.207 and 2.042 for Jos. Rain fade levels in worst month in both study locations are about 50% higher than levels in the average year, which suggests the need for alternative methods of mitigating rain fade such as adaptive power control schemes.

Plasma Sprayed Red Mud-Fly Ash Composite Coatings on Mild Steel: A Comprehensive Outline

2021-07-22T04:40:08+00:00

The present investigation aims at evaluating the effect of fly ash addition on coating characteristics of pure red mud. Plasma sprayed coatings composed of red mud and a varying percentage of fly ash on mild steel were considered for the study. Coating technologies have already gained a promising momentum for the creation of emerging materials in the last few decades. Plasma spraying technique was used with varying levels of power namely 6, 9, 12 and 15 kW. Plasma spray is one of the most widely used techniques involved in surface modification by improvement of wear resistance, which may affirm the great versatility and its application to a wide spectrum of materials. Investigations of the coatings focused on tribological properties like sliding wear behaviour, wear morphology, wear mechanism and frictional force. Different coating characteristics like surface morphology, hardness, porosity, thickness and new phase formation are studied. The sustainability of these coatings towards high temperature at air environment up to 1000°C is evaluated by finding their adhesion strength. DSC and TGA techniques are implemented to observe the coating behaviour to heat. The coatings show remarkable resistance towards high temperature by virtue of adhesion strength compensation. It is feasible to use these coatings limiting < 800°C otherwise dislodging of coating from metal. Fly ash with 10, 20 and 50% by weight was mixed with red mud and sliding wear test performed using a pin on disc wear test machine. The wear test was performed for sliding distance up to 942 m with track diameter of 100 mm and at a sliding speed of 100 rpm (0.523 m/s); applying a normal load of 10 N for a maximum duration of 30 minutes. The variation of wear rate and frictional force with that of sliding distance and time has been presented. The addition of fly ash with red mud reduces the wear rate by enhancing the coating property. But the optimum percentages of fly ash required for better coating material still impact a question mark for the researchers. It is observed that for the early stage the wear rate increases slowly and then rises drastically with sliding distance for all coating type and finally becomes stagnant. Operating power level proved to be the remarkable variable for different coating property. In our observation the coatings wear resistance (reverse of wear rate) decreases until an optimum value at 12 kW, afterwards indicating some other dominating parameters. Significant wear resistance was visible with the addition of fly ash due to an increase in bond strength and dense film at the interface. Wear rate decreases with operating power up to 12 kW, thereafter increases with initiating other dominating parameters. The present study concludes that, red mud coatings possess acceptable thermal properties. Fly ash is a beneficiary reinforcing agent for red mud, and the composite can be coat able with favoring surface properties. These coatings can be operated at high temperature. It is observed that, these composite coatings can also be employed for suitable trbological applications. Plasma generating power, adversely affect the coating morphology. Our work is a portfolio for researcher to discover many other aspects of red mud and its composite coatings. Study of corrosion wear behaviour may be implemented by future investigators to find its distinct application areas.

A New Look at Formulation of Charge Storage in Capacitors and Application to Classical Capacitor and Fractional Capacitor Theory

2021-07-22T04:42:46+00:00

In this study, we revisit the concept of classical capacitor theory-and derive a possible new explanation of the definition charge stored in a capacitor. We introduce a ‘capacity function’ with respect to time to describe the charge storage in a classical capacitor and for a fractional capacitor. The observation regarding capacitor breakdown is very interesting. This study practically described for DC link capacitors (in power supply circuits), that the capacitor breaks down even it were never exceeded its maximum voltage limit. Here we will describe that the charge stored at any time in a capacitor as a ‘convolution integral’ of defined capacity function of a capacitor and voltage stress across it which comes from the causality principle. This approach, however, is different from the conventional method, where we multiply the capacity and the voltage functions to obtain charge stored. This new concept is in line with the observation of that charge stored as a step function and the relaxation current in form of impulse function for ‘ideal geometrical capacitor’ of constant capacity; when an uncharged capacitor is impressed with a constant voltage stress. Also this new formulation is valid for a power-law decay current that is given by ‘universal dielectric relaxation law’ called as ‘Curie von-Schweidler law’, when an uncharged capacitor is impressed with a constant voltage stress. This universal dielectric relaxation law gives rise to fractional derivative relating voltage stress and relaxation current that is formulation of ‘fractional capacitor’. A ‘fractional capacitor’ we will discuss with this new concept of redefining the charge store definition i.e. via this ‘convolution integral’ approach, and obtain the loss tangent value. We will also show how for a ‘fractional capacitor’ by use of ‘fractional integration’ we can convert the fractional capacity a constant that is in terms of fractional units (Farads per sec to the power of fractional number); to normal units of Farads. From the defined capacity function, we will also derive integrated capacity of capacitor. We will also give a possible physical explanation by taking example of porous and non-porous pitchers of constant volume holding water and thus, explaining the various interesting aspects of a classical capacitor and a fractional capacitor that we arrive with this new formulation; and also relates to a capacitor breakdown theory-due to electrostatic forces. Study investigates the charge stored in a capacitor, as a function of time is not the usual multiplication operation of capacity and voltage; instead, the charge is convolution integral of these two functions, derived from causality principles. With this formulation, we showed for a fractional capacitor, the charge goes to infinity for large times, when the fractional capacitor is placed on a constant voltage; and is in line with earlier fractional order models and observations. With this formulation of convolution integral, this study also showed that the relaxation current is in the form of impulse function for ideal geometrical capacitor of constant capacity, when stressed by a constant voltage and for fractional capacitor with power-law decay current that is given by universal dielectric relaxation law called as Curie von-Schweidler law. Practically, this new ‘generalized- formulation’ has use while getting the charge stored in a capacitor which is a function of time with time-varying voltage stress across it, and to convert the fractional capacity units to usual capacity units in Farads.