Potential Energy Values Research Articles

The Synoptic Characteristics, Causes, and Mechanisms of Kahlaa Tornado in Iraq on 14th April 2016

In this study, an analysis of the synoptic characteristics, causes and mechanisms of Kahlaa tornado event was carried out. This tornado occurred on 10:30 UTC (1:30 pm Iraq Local Time) on 14 April 2016 to the north of Kahlaa town in Maysan governorate. We analyzed surface and upper charts, weather conditions, the damage indices, the dynamical features and the instability of the tornado. The analysis showed that there was a low pressure system which was an extension of the Monsoon low in addition to a supercell thunderstorm and a jet stream aloft. The cold trough and high relative vorticity at 500 hPa level, the humid warm wind blowing from the south and the dry cold wind from the north contributed to the initiation of the tornado. According to the damage amount, Kahlaa tornado can be classified as EF2 degree (considerable) on Enhanced Fujita scale. Three indices were calculated to estimate the instability of the tornado. The values of the convective available potential energy (CAPE), K-index, and lifted index were (≥2500 J/kg), (35.3 oC), and (-7), respectively. All these indices confirmed the instability required to form severe thunderstorm essential to tornado formation. Although the forecasting of tornadoes occurrence is difficult, there would be indications that may lead to expect of occurrence. These may include the availability of moisture, heat, and significant wind direction changes with altitude. However, the vital factors were the existence of high instability and a supercell thunderstorm.

Urban-climate interactions during summer over eastern North America

The urban heat island is a representative urban climate characteristic, which can affect heat-stress conditions and extreme precipitation that are closely connected with human life. Better understanding of urban-climate interactions, therefore, is crucial to ultimately support better planning and adaptation in various application fields. This study assesses urban-climate interactions during summer for eastern North America using regional climate model simulations at 0.22° resolution. Two regional climate model experiments, with and without realistic representation of urban regions, are performed for the 1981–2010 period. Comparison of the two experiments shows higher mean temperatures and reduced mean precipitation in the simulation with realistic urban representation, which can be attributed primarily to reduced albedo and soil moisture for the urban regions in this simulation. Furthermore, the mean temperature and precipitation in the simulation with improved urban representation is also closer to that observed. Analysis of short-duration precipitation extremes for climatologically different sub-regions, however, suggests that, for higher temperatures, the magnitudes of precipitation extremes are generally higher in the simulation with realistic urban representation, particularly for coastal urban regions, and are collocated with higher values of convective available potential energy and cloud fraction. Enhanced sea and lake breezes associated with lower sea level pressure found around these regions, contribute additional water vapor and further enhance dynamic convective development, leading to higher precipitation intensities. Analysis of temperature extremes clearly demonstrates that urban regions experience aggravated heat-stress conditions due to relatively higher temperatures despite reduced relative humidity. Double the number of extreme heat spells lasting six or more days are noted for the coastal urban regions in the study domain. This study, in addition to demonstrating the differences in urban-climate interactions for climatologically different regions, also demonstrates the need for better representation of urban regions in climate models to generate realistic climate information.

Climatology of Convective Storms in Estonia from Radar Data and Severe Convective Environments

Data from the C-band weather radar located in central Estonia in conjunction with the latest reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF), ERA5, and Nordic Lightning Information System (NORDLIS) lightning location system data are used to investigate the climatology of convective storms for nine summer periods (2010–2019, 2017 excluded). First, an automated 35-dBZ reflectivity threshold-based storm area detection algorithm is used to derive initial individual convective cells from the base level radar reflectivity. Those detected cells are used as a basis combined with convective available potential energy (CAPE) values from ERA5 reanalysis to find thresholds for a severe convective storm in Estonia. A severe convective storm is defined as an area with radar reflectivity at least 51 dBZ and CAPE at least 80 J/kg. Verification of those severe convective storm areas with lightning data reveals a good correlation on various temporal scales from hourly to yearly distributions. The probability of a severe convective storm day in the study area during the summer period is 45%, and the probability of a thunderstorm day is 54%. Jenkinson Collison’ circulation types are calculated from ERA5 reanalysis to find the probability of a severe convective storm depending on the circulation direction and the representativeness of the investigated period by comparing it against 1979–2019. The prevailing airflow direction is from SW and W, whereas the probability of the convective storm to be severe is in the case of SE and S airflow. Finally, the spatial distribution of the severe convective storms shows that the yearly mean number of severe convective days for the 100 km2 grid cell is mostly between 3 and 8 in the distance up to 150 km from radar. Severe convective storms are most frequent in W and SW parts of continental Estonia.

Extreme wind climate of the Arabian Peninsula characterized by using WRF simulation

Wind hazard is one of the most severe natural hazards. Structures and infrastructure can be vulnerable to wind load effects due to extreme wind speeds. Mitigation and the reduction of wind-related risks of structures and infrastructures can be made by considering the wind load effects within the structural design process. Building design codes or standards for some countries in the Arabian Peninsula do not formally define the wind load effects. For countries with wind load provisions in their building codes and standards, the spatial resolution of design wind speeds may not be sufficient to cover many cities or areas. To date, there has not been a comprehensive study on the extreme wind hazards at the design level in the Arabian Peninsula. Extreme wind hazards have been conventionally evaluated by using historical surface observations. However, an investigation showed that many meteorological stations in the Arabian Peninsula cannot be used to evaluate the design wind speeds due to low data quality or insufficient sampling resolution. This study used the Weather Research and Forecasting (WRF) model to obtain data with a high spatial-temporal resolution. The simulated extreme wind speeds across the Arabian Peninsula were characterized statistically. Spatial distributions of the extreme wind speeds and their associated attributes were investigated. The simulated wind speeds were separated into convective event-induced wind speeds and synoptic wind speeds to obtain the design wind speeds. The convective wind events were identified using a statistical algorithm defining the threshold values of the Lifted Index and the Convective Available Potential Energy values. A numerical parametric cyclone model was used to simulate the cyclone-induced extreme wind speeds for the southern coastal regions of the Arabian Peninsula. The design wind speeds were evaluated by using the most appropriate probability distribution and preferred fitting method. Contour maps of various return period wind speeds were developed.

ENERGY TRANSFORMATION MECHANISM OF A GAS BUBBLE COLLAPSE IN THE FREE-FIELD1)

Both the experiment method and numerical simulation method are applied in this paper to investigate the energy transformation mechanism of a gas bubble collapseing in the free field. The bubble radius, velocity and acceleration of the bubble evolution process are obtained according to the experimental results via the schlieren method. These parameters are substituted~into the bubble potential energy and kinetic energy equation to explain the energy changing. By using the CFD simulation method, a three-dimensional model with reformulated mass conservation equation and momentum equation considering the weakly compressibility, is introduced to discuss the bubble collapse process. The pressure and velocity distribution around the bubble are extracted from the simulation results in order to analyze the energy transformation mechanism. The results show that (i) the relation between the potential energy and bubble radius maintains the positive correlation, with the increasing of the potential energy, the kinetic energy decreases significantly. The value of potential energy is maximum at the end of the bubble expanding, and the kinetic energy of free field returns to zero at the same time. (ii) During the shrinking stage, a high-pressure area appears around the bubble, and gradients of velocity and pressure are higher than the other area in the free field. The high-pressure area is shrinking gradually when the bubble is collapsing. (iii) The potential energy transforms into kinetic energy during the whole process of the bubble evolution, and the kinetic energy is form of wave energy. A shock wave is captured when the bubble collapse, and the most of bubble energy transform into wave energy of the shock wave at this time.

A density functional theory study of molecular H2S adsorption on (4,0) SWCNT doped with Ge, Ga and B

The molecular adsorption of hydrogen sulfide has been investigated theoretically by using Density Functional Theory for gallium (Ga), germanium (Ge) and boron (B) doped (4,0) single-walled carbon nanotubes (SWCNTs). The method of B3LYP was utilized with basis sets of 6-31G(d,p) and LANL2DZ. Adsorption energy and adsorption enthalpy, HOMO and LUMO energy values, HOMO-LUMO energy gap, chemical hardness, chemical potential, electronegativity and Gibbs free energy values have been evaluated in this study. All doped SWCNT structures have negative Gibbs free energy and adsorption energy values which make these clusters promising for the removal of H2S by adsorption. However, Ge doped SWCNT cluster has the lowest HOMO-LUMO energy gap and chemical potential, highest electronegativity with minimum adsorption energy values when compared to other clusters. Furthermore, it is softer than other metal doped SWCNT clusters due to the lower chemical hardness value.

Molecular dynamics simulation of the roles of roughness ratio and surface potential energy in explosive boiling

Nanostructure can apparently affect explosive boiling through surface roughness that functions as a cavity for activating the bubble nucleus. In this work, the effect of surface roughness on the explosive boiling of water film over the copper surfaces with nanochannels having different heights and spacing is investigated. It is found that the increase in the roughness ratio by raising the channel height can substantially promote the onset time of boiling, increase the temperature and heat flux of water, and reduce the interfacial thermal resistance. The increase in roughness ratio by reducing the channel spacing has a promotion effect first and then a weakening effect on the boiling heat transfer. A critical channel spacing is proposed to address this effect on boiling heat transfer on surfaces with increasing roughness ratio by reducing the channel spacing. Moreover, a two-dimensional surface potential energy is used to address the relationship among the roughness ratio, interaction potential energy, and explosive boiling characteristics of the liquid molecules on the structured surfaces. The absolute value of surface potential energy increases with increasing roughness ratio with an increase average rate of 7.1 eV. It is concluded that, when the channel spacing exceeds the critical value, the major reason for the enhanced heat transfer by increasing the roughness ratio is essentially the improvement of the surface potential energy by increasing the heat transfer area. Further investigations on nanochannels with different heights and spacing indicate that the critical channel spacing of 1.444 nm is also suitable for more nanochannel surfaces. The findings of this study can help for a better understanding of the mechanisms of explosive boiling of various fluids on nanostructured surfaces by the surface potential energy.

Heavier Inner-core Rainfall of Major Hurricanes in the North Atlantic Basin than Other Global Basins

AbstractBased on 19 years of precipitation data collected by the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) mission, a comparison of the rainfall produced by tropical cyclones (TCs) in different global basins is presented. A total of 1789 TCs were examined in the period from 1998 to 2016 by taking advantage of more than 47,737 observations of TRMM/GPM 3B42 multi-satellite derived rainfall amounts. The axisymmetric component of the TC rainfall is analyzed in all TC-prone basins. The resulting radial profiles show that major hurricanes in the Atlantic basin exhibit significantly heavier inner-core rainfall rates than those in any other basins. To explain the possible causes of this difference, rainfall distributions for major hurricanes are stratified according to different TC intensity and environmental variables. Based on the examination of these parameters, we found that the stronger rainfall rates in the Atlantic major hurricanes are associated with higher values of convective available potential energy, drier relative humidity in the low to middle troposphere, colder air temperature at 250hPa, and stronger vertical wind shear than other basins. These results have important implications in the refining of our understanding of the mechanisms of TC rainfall.

Impact of Horizontal Grid Resolutions for Thunderstorms Simulation over Bangladesh Using WRF-ARW Model

In this paper, an attempt has been made to study the physical and dynamical characteristics of three thunderstorms that occurred on 06 May 2017 over Mymensingh, Chuadanga, and Sylhet in Bangladesh by the WRF-ARW model of 5 and 10 km horizontal resolutions, and to find out the impacts of horizontal grid resolution for simulating thunderstorm events. The model was run for 48 h using global Final Analysis (FNL) data. Various meteorological parameters such as Mean Sea Level Pressure (MSLP), wind pattern at several pressure levels, relative humidity, and radar reflectivity along with the atmospheric instability index are analyzed and compared with the observed data of Bangladesh Meteorological Department (BMD). The model has captured the low pressure area, the conjugation of easterly and westerly wind, the presence of strong convection, high magnitude of vertical wind shear, marked dry-line, updraft, and downdraft reasonably well for the finest grid resolution. But the convective available potential energy (CAPE) value is found almost similar near the places of occurrence for both resolutions. The model performance is found precisely well for the finest than that of coarse horizontal grid resolution.
 Dhaka Univ. J. Sci. 69(1): 43-51, 2021 (January)

МОДЕЛЮВАННЯ ПРОЦЕСУ ДЕЗІНТЕГРАЦІЇ РУДНОЇ ПОРОДИ В БАРАБАННОМУ МЛИНІ З ВИКОРИСТАННЯМ МЕТОДУ СКІНЧЕНИХ ЕЛЕМЕНТІВ

Розглянуто особливості руху рудних матеріалів в барабанному млині. Розроблено математичну модель процесу подрібнення рудних матеріалів з позиції балансу енергетичних величин процесу руйнування За використанням методу скінчених елементів показано, що виділений в будь-якому місці елемент завантаження піддається деформації з боку сусідніх елементів завантаження (шматків руди) в умовах всебічного нерівнокомпонентного стиснення контактними силами. Проаналізовано вплив напрямку сил контактного тертя при стисненні на ефективність руйнування рудної маси Данні сили суттєво впливають на появу максимальних зсувних (дотичних) напружень, які залежать від максимальних нормальних напружень, що виникають в шматках рудної породи Показана можливість керування режимами навантаження для підвищення ефективності процесу подрібнення.

Co-Digestion of Household Black Water with Kitchen Waste for a Sustainable Decentralized Waste Management: Biochemical Methane Potential and Mixing Ratios Effects

The generation of anthropogenic wastes, such as household human feces and kitchen waste, has resulted in a severe environmental impact. Sustainable management approaches to address disposal challenges and harness potential nutrient and energy values are urgently needed. This investigation assessed the anaerobic co-digestion of food waste and black water to identify the biochemical methane potential. The household kitchen waste showed improved performance at a dilution ratio of 50% with biochemical methane potential of 265 mL CH4/g volatile solid (VS), and that of the black water was 220 mL CH4/g VS without dilution. This trend indicates their easy biodegradation/digestibility and potential for energy recovery. The kitchen waste equal mix ratio of 50% v/v with the black water had the highest biochemical methane potential of 295.13 mL CH4/g VS when co-digested. High performance was due to the comparative balance in substrate concentrations that offered robust methanogenic activities without inhibitions. The effluent total chemical oxygen demand reduction of ∼90% and other physicochemical parameters showed that the codigestion treatment (kitchen waste and black water 50:50% v/v) was efficient. The codigestion route could offer a decentralized wastewater management system for energy recovery.

Study of Charge transfer complexes of chlorothiazide

The CT-complexes of chlorothiazide (n-donor) with picric acid, 3, 5-dinitrobenzoic acid (pi-acceptor) and iodine (sigma-acceptor) were investigated at different temperatures and solvents. These complexes were investigated in polar solvents (methanol, acetonitrile) and nonpolar solvents (dichloromethane and chloroform). The structures of the CT-complexes were studied by 1HNMR, infrared spectra and elemental analyses. The donation method was occurred from the lone pair of electron of nitrogen atom in chlorothiazide to pi- acceptors (n→ π*) and to sigma-acceptor (n–σ). Scanning electronic microscopy (SEM) shows images of chlorothiazide with 3,5-dinitrobenzoic acid, indicates that the produced complex is crystalline with a rod-like shape as the major crystals shapes. The molecular composition of the charge transfers complexes was 1:1 ratio (donor: acceptor) which determined by spectrophotometric titration. The extinction coefficient, eCT, the formation constant, KCT, transition dipole moment (μ), the oscillator strength (f), resonance energy (RN), ionization potential IP and transition energy (ECT) values of the complex were calculated.

Modeling of Lightning Events using WRF-derived Microphysical Parameters

Numerical simulation of lightning events in Bangladesh has been carried out by using Weather Research and Forecasting Model with Advanced Research Dynamic solver (WRF-ARW). Three major lightning events have been considered for the case study; Case_1, lightning occurrence in Netrokona district in March 24 2017, Case_2, lightning event in Barishal district in April 23 2017, and case_3, lightning event in Sherpur district in April 29, 2018. The model simulation was run in 9 km and 3 km of horizontal resolution using six hourly NCEP-FNL datasets. Yonsei University (YSU) PBL scheme, Rapid Radiative Transfer Model (RRTM) long-wave scheme for radiation, and Kain-Fritsch cumulus parameterization scheme is used for this study. The obtained results from the simulation could reasonably capture the lightning condition of the atmosphere for all the three cases. The WRF simulation give reasonable agreement with the available observational data with some spatial and temporal variations, for example the Convective Available Potential Energy (CAPE) values observed are 1299 J/Kg, 3150 J/kg, 1221 J/kg and CAPE values simulated are 1618 J/kg, 3275 J/kg and 1023 J/kg for case_1, case_2 and case_3 respectively. The regression analysis of the flash count with the microphysical parameters is also studied. It is found that there is strong correlation between the lightning flash counts with the microphysical parameters. This study will help to understand the lightning better and will help to design a better lightning forecasting system.
 The Dhaka University Journal of Earth and Environmental Sciences, Vol. 8(2), 2019, P 41-50

Hayvansal Atıkların Potansiyel Biyogaz Enerji Değerinin Belirlenmesi: Antalya Örneği

Increasing the world population will increase the demand for new energy sources in the future. Waste generated as a result of agricultural activities can be considered as a sustainable energy source. Animal manure that occurs from livestock activities can be shown as an energy source if managed properly. Antalya province and its region, where agriculture and tourism are intense, have been chosen as the study area. In the study, taking into account the data of Turkey Statistical Institute in 2019, for cattle animal breeding the numbers of dairy and beef cattle; for ovine animal breeding the numbers of sheep and goats; for poultry, the numbers of laying hen, turkeys, geese and duck were evaluated. Manure amounts and potential biogas energy values were calculated considering the animal numbers of Antalya province in 2019. The amount of electricity and natural gas energy that can be obtained in this potential biogas energy is also calculated. The obtained results are compared with the relevant literature and calculations are made for the existing biogas potential. As a result of the research, it was calculated that the amount of manure that can be obtained from animal waste in Antalya province could be 3,821.86 million kg and the potential biogas energy could be 45.57 million MJ. It has been calculated that the total amount of biogas that can be obtained is equivalent to approximately 253.23 million kWh of electrical energy or 43.90 million m3 of natural gas energy. As a result, considering the energy need of Antalya province, it can be said that an economic gain can be achieved by utilizing animal wastes for energy production.

Multitechnique Observations on the Impacts of Declining Air Pollution on the Atmospheric Convective Processes During COVID-19 Pandemic at a Tropical Metropolis.

The present study addresses the impacts of reduced anthropogenic activities during the lockdown period of COVID-19 pandemic on the aerosol concentration, treated as heat absorbing agent, and on the related atmospheric processes, using ground-based and spaceborne measurements over a highly polluted Indian metropolis, Kolkata. The investigation reveals that reduced aerosol concentrations during the pre-monsoon of 2020, when the lockdown was implemented, decreased atmospheric instability as indicated by low values of the convective available potential energy (CAPE). This hindered the abundance of aerosols above the atmospheric boundary layer. Also, micro rain radar (MRR) observations showed a significant reduction of convective precipitation occurrences over Kolkata during this period. The back trajectory analysis has revealed the absence of continental component toward the wind clusters associated with rain occurrences during pre-monsoon 2020. This resulted in increased occurrences of stratiform rain events during the pre-monsoon of 2020 compared to the same period of previous years.

Exploring Inland Tropical Cyclone Rainfall and Tornadoes under Future Climate Conditions through a Case Study of Hurricane Ivan

AbstractThe overarching purpose of this study is to investigate the impacts of anthropogenic climate change both on the rainfall and tornadoes associated with tropical cyclones (TCs) making landfall in the U.S. Atlantic basin. The “pseudo–global warming” (PGW) approach is applied to Hurricane Ivan (2004), a historically prolific tropical cyclone tornado (TCT)-producing storm. Hurricane Ivan is simulated under its current climate forcings using the Weather Research and Forecasting Model. This control simulation (CTRL) is then compared with PGW simulations in which the current forcings are modified by climate-change differences obtained from the Community Climate System Model, version 4 (NCAR); Model for Interdisciplinary Research on Climate, version 5 (MIROC); and Geophysical Fluid Dynamics Laboratory Climate Model, version 3 (GFDL). Changes in TC intensity, TC rainfall, and TCT production, identified for the PGW-modified Ivan, are documented and analyzed. Relative to CTRL, all three PGW simulations show an increase in TC intensity and generate substantially more accumulated rainfall over the course of Ivan’s progression over land. However, only one of the TCs under PGW (MIROC) produced more TCTs than CTRL. Evidence is provided that, in addition to favorable environmental conditions, TCT production is related to the TC track length and to the strength of the interaction between the TC and an environmental midlevel trough. Enhanced TCT generation at landfall for MIROC and GFDL is attributed to increased values of convective available potential energy, low-level shear, and storm-relative environmental helicity.

A case study of a derecho storm in dry, high-shear environment

The present study examines the origin and environmental conditions of the severe convective windstorm on September 17, 2017, which affected several countries in the central and southeastern Europe, above all Serbia and Romania. The large area of the damage swath (at least 500 km long) and high wind gusts (up to 40 m/s) would classify this event as a derecho or at least as a storm very similar to derechos (with respect to newer definition proposals). Small-scale bow echoes were found in areas with highest reported wind gusts, and some thunderstorms within the storm-producing convective system were probably supercells. The existence of high wind shear and storm rotation could be also related to the significant rightward deflection of the system with respect to the mean wind and propagation of other thunderstorms and systems observed on that day. In contrary to many other known derecho events, this storm propagated toward a very dry airmass exhibiting only low or moderate convective available potential energy (CAPE) values. This is shown by soundings, ECMWF model outputs, and vertical profiles from the IASI L2 satellite sounder. Several convective parameters (e.g. CAPE, downdraft CAPE, derecho composite parameter, 0-3-km relative humidity, 0-6-km shear) were evaluated and compared with proximity soundings of other described European derechos or with the available climatology. The possibility of a balance between the cold pool-generated horizontal vorticity and the environmental shear is also discussed. It is concluded that identification of low-level humidity sources (with aid of storm-relative wind vectors or streamlines) can be important in forecasting of thunderstorm systems moving toward an airmass, which is seemingly too dry for development and maintenance of deep convection. It is also shown that due to low CAPE values, some composite parameters would not indicate favourable conditions for a long-lived convective system. The lack of radiosonde observations can be partially supplemented by data from the IASI L2 sounder, which profiles can be largely different from model forecasts, showing much drier air in the mid- and upper troposphere in this case. It is concluded that due to the absence of strong synoptic forcing and larger pressure gradient at surface, convective processes played major role in the windstorm development. The presence of high temperature lapse rates at low- and mid-levels, high wind shear and unusually dry pre-storm airmass could be considered as the most important signatures related to the storm severity.

Alternative Evaluation of Olive Pomace (Pirina) as Production Waste

With the increasing need for energy, energy studies to be obtained from waste gain importance. In this study, it has been tried to determine the amount of biogas energy that can be obtained from olive pomace (pirina), which is produced by processing oil olives. Numerical maps of pirina amounts and potential biogas energy values and location maps of the proposed pirina processing plant were created. The necessary calculations were made by comparing the obtained results with the relevant literature information. In the study, the current potential biogas energy amount was calculated, maps were created and the electricity and gasoline energy equivalent levels of this energy were tried to be calculated using the 2015-2019 data of the Mediterranean, Aegean and Marmara Regions. The total potential amount of pirina in the research area is 1853375.7 tons and the potential biogas energy amount that can be obtained is 33360762.4 MJ. Pirina, which is the production waste after pressing the olives for oil, can be used for energy production. By using pirina to obtain biogas energy, both the utilization of pirina and the development of the regions will be provided.

Virial-potential-energy correlation and its relation to density scaling for quasireal model systems.

In this paper, we examine the virial- and the potential-energy correlation for quasireal model systems. This correlation constitutes the framework of the theory of the isomorph in the liquid phase diagram commonly examined using simple liquids. Interestingly, our results show that for the systems characterized by structural anisotropy and flexible bonds, the instantaneous values of total virial and total potential energy are entirely uncorrelated. It is due to the presence of the intramolecular interactions because the contributions to the virial and potential energy resulting from the intermolecular interactions still exhibit strong linear dependence. Interestingly, in contrast to the results reported for simple liquids, the slope of the mentioned linear dependence is different than the values of the density scaling exponent. However, our findings show that for quasireal materials, the slope of dependence between the virial and potential energy (resulting from the intermolecular interactions) strongly depends on the interval of intermolecular distances that are taken into account. Consequently, the value of the slope of the discussed relationship, which enables satisfactory density scaling, can be obtained. Interestingly, this conclusion is supported by the results obtained for analogous systems without intermolecular attraction, for which the value the slope of the virial-potential-energy correlation is independent of considered intermolecular distances, directly corresponds to the exponent of the intermolecular repulsion, and finally leads to accurate density scaling.

Effect of Different Sized Multi Walled Carbon Nanotubes on the Barrier Potential and Trap Concentration of Malachite Green Dye Based Organic Device

Abstract Present work shows effect of 8 nm diameter and 30 nm diameter multi walled carbon nanotubes (MWCNT) on the barrier potential and trap concentration of Malachite Green (MG) dye based organic device. MWCNTs are basically a bundle of concentric single-walled carbon nanotubes with different diameters. In this work, ITO coated glass substrate and aluminium have been used as front electrode and back electrode respectively and the spin coating method is used to prepare the MG dye based organic device. It has been observed that both barrier potential and trap concentration are in correlation. Estimation of both these parameters has been done from current-voltage characteristics of the device to estimate the trap energy and the barrier potential of the device. Device turn-on voltage or the transition voltage is also calculated by using current-voltage characteristics. In presence of 8 nm diameter MWCNT, the transition voltage is reduced from 3.9 V to 2.37 V, the barrier potential is lowered to 0.97 eV from 1.12 eV and the trap energy is lowered to 0.028 eV from 0.046 eV whereas incorporation of 30 nm diameter MWCNT shows reduction of transition voltage from 3.9 V to 2.71 V and a reduction of barrier potential and trap concentration from 1.12 eV to 1.03 eV and from 0.046 eV to 0.035 eV respectively. Presence of both 8 nm diameter and 30 nm diameter MWCNT lowers trap energy approximately to 39% and 24% respectively and lowers barrier potential approximately to 13% and 8% respectively. Estimation of barrier potential is also done by Norde method which shows lowering of the value from 0.88 eV to 0.79 eV and from 0.88 eV to 0.84 eV in presence of both 8 nm and 30 nm diameter multi walled carbon nanotubes respectively. Calculation of barrier potential from both the I-V characteristics and Norde method are in unison with each other. Indication of enhancement of charge flow in the device can be ascribed to the truncated values of barrier potential and trap energy.