The effect of ambient temperature on the performance of a 130 W polycrystalline photovoltaic (PV) module was explored in this study. With field data at Ilorin, Kwara State, Nigeria, the output current of a 130 W PV module was modeled using ambient temperatures. For two weeks of field observations, an instrumented meteorological mast was set up at an experimental site (80 30'N, 40 33'E) at Kwara State Polytechnic in Ilorin, Nigeria, for two weeks of field observations (1st to 14th July 2019). At 10-second intervals, the PV cell output current and ambient temperatures from the instrumented meteorological mast were recorded. A data logger (fabricated) storage module was used to store the sampled data. The saved data was further reduced to 20 min averages using the Microcal Origin data analysis program after erroneous measurement values were removed (quality assurance and quality control). With the MBE of 0.01 Wm-2, RMSE of 0.13 Wm-2, and r = 0.61, the predicted output current, OCP, was compared to the actual measured output current, OCm, and very good agreement was found. As a result, even with a short set of measured ambient temperature data, the estimator explored in this study is capable of predicting the performance of a polycrystalline PV cell in terms of its output current in the absence of direct measurement of the output current.
We solved the radial Schrödinger equation analytically using the Nikiforov-Uvarov method to obtain the energy eigenvalues and corresponding wavefunction in terms of Laguerre polynomials with the Generalized Yukawa potential (GYP). The present results are applied for calculating the mass spectra of heavy mesons such as charmonium ( cc ) and bottomonium (bb ) for different quantum states. The present potential provides excellent results in comparison with experimental data with a maximum error of 0.0157 GeV and work of other researchers.
Cadmium iodide (CdI2) thin films with varying grain size and thickness were studied for exploring the strategy of controlling bandgap (Eg) in the thin film-materials. The grain size (D) was calculated from the X-ray diffraction (XRD) and was found to increase with increasing the thickness (L) of the film. A variation of the refractive index (n) with the variation of L was observed, which might be due to the variation of both density and electronic structure. However, n was found to decrease with increasing the wavelength of light. The optical absorption spectra showed both allowed direct and indirect interband transitions across a fundamental gap. It was found that both indirect and direct Eg decrease with increasing L and that the indirect Eg was lower than the direct Eg, confirming the results of the earlier band structure calculations. The direct Eg was also found to decrease with increasing D. The results demonstrate the possibility of controlling and manipulating Eg by adjusting D and L.
Using the generalised gradient approximation (GGA) and an ultrasoft pseudopotential, we report on the structural, electrical, vibrational, and superconducting properties of LiFeP, an iron pnictide superconductor. The 3s state of P is regulated in the region considerably below the Fermi level, the 3s state of Li is above the Fermi level, and the 3d state of Fe is close to the Fermi level. The underlying bands close to the Fermi level reveal the metallic character of LiFeP. The positive frequencies of the phonon dispersion curves confirm the material's dynamical stability. A weak electron-phonon coupling (EPC), a measure of decreased electron scattering, indicates poor superconductivity in the material being studied. However, the big difference between the calculated TC results and the experimental data shows that to improve TC, the electron-phonon interaction needs to be 2.5–3.0 times stronger. Moreover, weak electron-phonon coupling is indicated by the effective interaction strength (N₀V) values and show superconducting nature.
The study explores seismic, electromagnetic, and well-log data to understand the investigated region's subsurface features and geologic events. Seismic data, local microseismic characteristics, and gravity anomaly were used to evaluate spatial and temporal patterns and how they relate. The data visualization plots revealed the Monte Carlo distributions of microseismic events, which is necessary for conducting the b-value analysis. Gravity survey data, mapped in graphics of strews, proved to be more complex relationships between gravity and elevation, declaring intricate patterns of actual underground structures. Imagery, created with real-time electromagnetic surveys, which were mimicked on an apparent resistivity pseudo section, revealed important information regarding resistivity anomalies – an essential prerequisite for identifying fluid pathways and fracture networks. A study of hydraulic fracturing parameters was carried out to establish the relationship between injection rates and pressures with fluid migration, proppant concentration, and others. Ultimately, the Bouguer gravity anomaly map created a spatial visual representation of density variations that, in turn, was helpful in geological interpretation. Accordingly, these conclusions reveal global ideas about the subsurface processes and thus enable effective geological studies and exploration of geological resources.
This study presents a water phantom study of verification of tangential breast treatment dose calculations in a two-dimensional treatment planning system (TPS) at the Department of Radiotherapy, in a National hospital in Sri Lanka. Measurements were made using a 0.6 cc Farmer-type cylindrical ionization chamber with an electrometer in a breast phantom made of water field Perspex structure. The measured doses in the breast were compared with calculations made on a two-dimensional radiotherapy treatment planning software THERAPLAN®PLUS version 3.55 using the digitized breast phantom contour. Overall, the measurements obtained from the TPS had an accuracy of ±5% compared to the direct measurements while most of the measurements lie within ±3%. And dose in the chest wall was below the tolerance level of the lung and heart. Thus, it was concluded that TPS calculations and dose distributions are within the clinically acceptable accuracy level of international standards (ICRU report 50).
Sri Lanka is well known for high-quality vein graphite, which can be exported with value addition at a higher price than the raw form to remain competitive in the global market. The present study aims at industrial scale production of Sri Lankan vein graphite above 99.9% purity level using ecofriendly and chemical methods. For the first time a novel mechanical floatation method was followed to purify vein graphite above 99% on mass scale. Acid leaching method was followed subsequently to remove most of the impurities from graphite at industrial scale as well. Subsequently, alkali-acid method was followed for further purification of graphite. The raw and treated graphite were subjected to X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis to verify any structural change resulting from the treatment process. XRD analysis showed that the crystalline structure of graphite has not significantly changed upon treatment. XPS and FTIR spectroscopic analysis also revealed that there is no apparent functional groups attached to graphite structure after treatment. SEM images demonstrated a flaky appearance of graphite without any clear changes in morphology even after the treatment with acids at commercial level quantitates. The results illustrated that combination of the flotation technique and chemical treatment allow graphite purification well above 99.9% carbon without significant structural changes.
We study the nonlinear electromagnetic wave propagation in inhomogeneous fibers in the anomalous dispersive regime. In order to include the inhomogeneous physical effects, the nonlinear Schrödinger (NLS) equation, which governs the solitary pulse propagation in optical fiber, is modified by adding terms for phase modulation and fiber power loss/gain. Lax pair construction and Hirota transformation are introduced in order to bilinearize and solve the modified inhomogeneous NLS equations. A general integrability condition is arrived for gain and loss cases. The modified NLS equations in the anomalous dispersive regime are then Hirota bilinearized, and exact bright solitons solutions are obtained. The analytical soliton solutions are also obtained. The results show that in both gain and loss cases the areas of the pulse envelopes remain preserved during the propagation in the fibers, demonstrating that bright solitary wave propagation is maintained in the cores. The results are discussed in detail.
Lead acid battery has long been recognized as a versatile cost-effective energy storage solution for applications, including automotive, renewable energy integration, and telecommunications. The present research aims to investigate the impact of specific additives such as carbon black and reduced graphene oxide on the positive electrode of lead oxide batteries. To assess the performance of lead oxide batteries, the electrode material is formulated by combining lead oxide, lead dioxide, and additives at appropriate ratios and characterized using XRD and SEM. The discharge capacity of each positive electrode is investigated using a two-electrode cell and results were compared with a similar commercial cell. When the rGO or carbon black ratio of the positive electrode is 0.4% (w/w), the respective discharge capacities of the battery were 276.4mAh and 243.68mAh which is well above the discharge capacity of a commercial battery under similar conditions. In addition, the respective voltage drops of the battery with each rGO and carbon black were 0.22V and 0.30 V which is significantly less than that of a similar commercial battery (1.07V). In addition, a stable capacity was observed in the rGO based battery during the chargedischarge cycling. These findings highlight the potential of rGO and carbon black as additives in improving the electrochemical performance of lead-acid batteries.
Graphene oxide (GO) and reduced graphene oxide (rGO) were prepared from high pure Sri Lankan vein graphite on a lab-scale as well as on a mass scale following an improved Hummer’s method and a thermal method with a goal of investigating the quality of final products. Both oxidation and reduction process in mass scale production process have been subjected to composition and condition change considering factors such as safety, cost-effectiveness, eco-friendliness, user friendliness, and waste disposal management. Raman, XPS, FTIR, XRD, SEM, and TEM spectroscopic analysis were conducted to verify the final products on oxidation of graphite and its successive reduction. Exfoliation of graphite layers into few-layer rGO with large lateral size (D50, ca. 45 m) is visible through TEM and SEM. The XRD, FTIR, and XPS analysis indicated that the graphite was successfully oxidized to GO and reduced back to rGO with fewer oxygen functionalities, equivalent to ca. 7 % wt. The C/O ratio in XPS reflects that the oxygen-containing moieties are twice as rich in GO compared to graphite. XPS and FTIR further revealed epoxide and carboxylic groups being the main oxidized products of GO. Raman spectra further verified the restoration of sp2 hybridized bonds on the reduction of GO. The rGO prepared at 1000 ºC showed rGO with high conductivity, high surface area, fewest oxygen functions and fewest defects than reported. The combination of spectroscopic analysis carried out in the investigation provided valuable information and knowledge on the chemically produced graphene like rGO on mass scale with good properties compared to similar studies. The study demonstrates directions for further improvement of the synthesis method exploring the ability to use naturally pure vein graphite towards quality graphene on a mass scale.
The conducting behaviour of Pure and Malachite green mixed Polyvinyl Chloride (PVC) samples prepared using the solution cast method in various ratios, was investigated using Ultraviolet (UV)transmittance, UV absorbance, Infrared (IR) transmittance, and X-ray Diffraction (XRD). The results show that UV transmittance decreases with sensitizer concentration in PVC. UV absorbance shows an increasing trend with the degree of sensitization. The formation of a charge transfer complex in a polymer matrix was inferred from these studies. Reduction in electronic bandgap and hence change in conductive behaviour is reported.
The extraordinary properties of graphene have made application of this wonder material in multidisciplinary domains. Promising applications of graphene and its composites have been made a reality through enormous scientific efforts to date. In the present era, the attention has to focus on the right choice of methodology analogous to each application. The prospective product range of graphene is broad, and the attentiveness of each application would be deviated accordingly. We believe priority should be given to the most essential needs among the vast variety of opportunities. Here we focus on methods followed in the production of graphene and composites and their applications in energy storage devices including batteries, capacitors, and fuel cells. Physical, chemical, and biological methodologies followed in minute scale synthesis as well as mass level are discussed. The information would be supportive of the development of more effective energy storage devices based on graphene in soon.
Discovery of graphene has enhanced attention on industrial scale production of graphene using natural graphite which involves oxidation followed by reduction processes. Aiming for the first time, mass scale production of graphite oxide from Sri Lankan vein graphite of natural purity 99.5% carbon, following an improved Hummer’s method was experimented at optimized conditions minimizing chemical, energy and time wastage. The present study further aimed at determination of pH and manganese ions on successive purification processes of graphite oxide. The X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) characterizations were followed for verification of products. The wastewater produced from graphite oxide preparation process was systematically tested for Mn2+ ion using Atomic Absorption Spectroscopy (AAS). XRD peaks verified the formation of graphite oxide successfully through a complete oxidation of graphite. FTIR spectrum exhibited characteristic peaks related to typical graphite oxide while SEM shows the typical morphological features. XPS analysis verified complete removal of Mn from graphite oxide after purification. AAS analysis reveals entire removal of Mn after several washing cycles using only water. The investigation concludes that even mass scale production of quality graphite oxide is possible from Sri Lankan pure vein graphite which can subsequently be used to produce precious graphene and derivatives for various high-end applications.
Arrival of the South-West monsoon in Sri Lankan region is an abrupt phenomenon and with this annual climatological event, many meteorological parameters such as rainfall, wind, pressure etc. would remarkably change. Therefore, determination of the SW monsoon onset is socio economically significant as it influences agriculture and hydropower generation. With the advent of satellite imagery, pattern recognition techniques have been implemented favorably for forecasting the SW Monsoon onset. This study explains a methodology based on the Objective Dialectical Classifier to determine the onset dates utilizing only the clouds images. Results obtained in this research match well with the onset dates determined by the regional authorities.
Interest in Quantum Dot Lasers stem mainly from the low threshold current which can result due to quantization of energy levels and change in density of state function. In the most used lasers, separate confinement heterostructures, the nanoscale active region is ‘built into’ the waveguide region (optical confinement layer, OCL) based on a wide gap semiconductor material.The most important characteristic of quantum dot laser is the amount of light it emits as current is injected into the device. The dependence of laser power output on current, cavity length, and various other parameters has been estimated based on the rate equations model. Linear relation has been obtained between power and current and as the cavity length increases, the slope of the power–current characteristic decreases.The external quantum efficiency indicates the efficiency of a laser device in converting the injected electron–hole pairs (input electric charges) to the photons emitted from the device (output light). External differential quantum efficiency decreases linearly with increasing cavity length. As the internal loss increases, the slope of external differential quantum efficiency versus cavity length increases. The internal quantum efficiency is independent of the geometrical properties of the laser device, such as the cavity length or the stripe width. Internal quantum efficiency is one of the main figures of merit that should be used in assessing the quality of the semiconductor wafer from which the quantum dot laser is manufactured.One of the most important device characteristics of a laser diode is the efficiency of conversion of the input electric power into output optical power. Power conversion efficiency is found to increase with increasing drive current, gets its maximum value and after that it decreases slightly with increasing drive current. Power conversion efficiency also depends on different parameters like cavity length, internal efficiency, and threshold current.
Borophene is a novel 2D material whose history goes back only as far as the year 2015. Borophene is one atom thick 2D boron sheet which depict excellent optical, electronic, metallic, semiconducting, high mechanical anisotropic, and photothermal properties. Also, due to borophene’s high mechanical strength, high specific capacity, and low diffusion barrier it poses as an ideal candidate as an anode material for metal metal-ion batteries. This is the avenue of interest of this review paper, where we intend to discuss the existing theoretical and experimental basis of various polymorphic structures of Borophene, as anode materials for metal-ion batteries.
Supercapacitors have been identified as one of the key energy storage devices with their excellent ability to bridge the gap between batteries and conventional capacitors in terms of power and energy. A great amount of research activities is being carried out to improve their performance to serve for worldwide day-to-day applications such as power backups, automobiles and power generators. This study is about determining the suitable active mass loading of reduced graphene oxide (RGO) based electrodes in solid state supercapacitors using cyclic voltammetry technique. The potential window of (0.01-1.2) V showed the highest single electrode specific capacitance (Csc) for the mass loading of 2 mg cm-2. As per the selected scan rates for the test, 10 mV s-1 exhibited the optimum Csc again for the same mass loading. Continuous cycling was done for 1000 cycles. Supercapacitor with the same mass loading had a higher Csc continuously throughout the 1000 cycles and also, its rate of reduction of Csc was lower.
The exact solution of the Feinberg–Horodecki equation for time-dependent harmonic vector potential has been investigated under a one-dimensional system. The quantized momentum and its corresponding un-normalized wave functions were explicitly obtained. The Fisher information (for time and momentum) and variance (for time and momentum) were calculated using expectation values of time and momentum via Hellman–Feynman theory (HFT). The time and momentum Shannon entropy were obtained using an existing formula. Numerical results were computed for time and momentum Fisher information to confirm the Cramer–Rao inequality. Another numerical results were obtained for time and momentum Shannon entropy to verify Bialynick-Birula, Mycielski (BBM) inequality. The effects of the potential parameters such as mass of the spring and the frequency on the theoretic quantities were fully examined. The new variance inequality was established using the inequalities of Fisher information. The established inequalities were confirmed by numerical results which also satisfied the popular Cramer–Rao inequality. The theoretic impetuses for Fisher information, variance, and Shannon entropy, respectively, were calculated and their variations with some potential parameters were studied.
Extruded biodegradable films based on Poly (butylene adipate-co-terephthalate) (PBAT) and Cassava starch (CS) at varying weights were prepared, and their relevant properties for packaging applications are here reported. Neither the peak position nor the intensity of the film’s distinctive infrared absorption peaks was altered by the addition of CS to PBAT. Therefore, adding CS to PBAT is solely a physical process. Experimental results show that the increase in CS content, the tensile strength, elongation at break, and the tear resistance of the composite are decreased. The "30% CS” included composite film was selected as the optimized composition since it is cost-effective while acquiring the required physical properties to be a better fit as a packaging material. However, the overall migration of residue on the surface of the “30% CS/PBAT” sample wasn’t in the acceptable range (<10 mg/dm2). Therefore, the developed product is suitable for use as a packaging material except for food packaging. Thus, the extrusion process needs to be further modified to be used as food packaging.
In presence of warm negative ion, propagation of ion-acoustic solitary waves has been investigated analytically in a plasma consisting of warm positive ion, warm positron and single-temperature non-isothermal electron. The necessary and sufficient conditions for the existence of compressive solitary waves are discussed critically along with the calculation of phase velocity, kinetic energy (K.E) and force (F) found out in this paper by this new analytical method. Some important general observations and Theorems related with this problem are highlighted that supports the results of previous authors. The Sagdeev potential function ψ(𝜙) [= - L(𝑢𝛼 )] against ϕ depicted graphically under the variation of different plasma parameters is the most important and interesting situations by this analytical method.
