Variation Of Physical Parameters Research Articles

Investigation of Self-heating Effects in Ultrathin FDSOI MOSFETS

This paper contains the design consideration of 18nm FDSOI MOSFET for mitigating the self-heating effects. As the device scaling reaches towards the nano regime, self-heating effects are quite significant. Increase in the lattice temperature will lead to decrease in the mobility and degradation of the drain current. Self-heating effects are investigated in FDSOI MOSFET by comparing different physical parameter variations like gate length, spacer thickness, buried oxide thickness and source/drain/metal contacts. It is being observed that the heat sinks used as metal contacts can reduce lattice temperature up to 62% and spacer size thickness can reduce it by 10%. However the buried oxide box thickness and gate length modifications do not have considerable impact on the self-heating.

Physical Properties and Impact Parameter Variations of Kepler Planets from Analytic Light-curve Modeling

Abstract We apply AnalyticLC, an analytic model described in an accompanying paper, to interpret Kepler data of systems that contain two or three transiting planets. We perform tests to verify that the obtained solutions agree with full N-body integrations, and that the number of model parameters is statistically justified. We probe non-co-planar interactions via impact parameter variations (TbVs), enabled by our analytic model. The subset of systems with a valid solution includes 54 systems composed of 140 planets, more than half of which are without previously reported mass constraints. Overall we provide: (i) estimates of physical and orbital properties for all systems analyzed; (ii) 102 planets with mass detections significant to better than 3σ, 43 of which have masses below 5 m ⊕; and (iii) 35 TbVs significant to better than 3σ. We focus on select systems showing strong TbVs, which can result from either interaction among the known transiting planets, or with a nontransiting object, and provide: (iv) a method to constrain the parameters of such unseen companions. These results are enabled by an accurate 3D photodynamical model, of a kind expected to become increasingly important for modeling multidecade photometric and composite (radial velocity, astrometry) data sets.

Enhancing irrigation water productivity and controlling salinity under uncertainty: A full fuzzy dependent linear fractional programming approach

An integrated simulation-optimization framework is developed under uncertainty to enhance irrigation water productivity and control salinity in an arid area. A full fuzzy dependent linear fractional programming approach is formulated by incorporating fuzzy dependent-chance programming, fuzzy credibility-constrained programming and linear fractional programming within a general framework of irrigation planning. Then, simulation module concerning water, salt balance process and crop water-salt production functions enables to quantify daily physical process of water and salt movement among the soil water, crop root zone and groundwater aquifers. Thus, this study can readily handle fuzzy uncertainty existing concurrently in the ratio objective (i.e., economic water productivity) through the concept of fuzzy dependent chance and double-sided constraints. It can also simultaneously provide the maximum credibility level that the objective is achievable and credibility levels implying that optimal solutions are believable. Besides, daily variations of simulated physical parameters are illustrated corresponding to management strategies. To demonstrate its applicability, it’s then applied to a case study of irrigation planning in the Jiefangzha Irrigation Subarea in Hetao Irrigation District, northwest China. Results can clearly analyze tradeoffs among satisfaction degree of fuzzy objective, fuzzy constraints and optimal solutions. Moreover, by examining different management targets and salt accumulation constraints, this study demonstrates the merits and importance of the work to promote irrigation water productivity and control salinity. Dynamic decision making of irrigation planning is possibly made by coupling daily simulation and optimization modules. Therefore, these findings can support decision makers to identify appropriate solutions for irrigation planning.

A New Wearable System for Sensing Outdoor Environmental Conditions for Monitoring Hyper-Microclimate.

The rapid urbanization process brings consequences to urban environments, such poor air quality and the urban heat island issues. Due to these effects, environmental monitoring is gaining attention with the aim of identifying local risks and improving cities’ liveability and resilience. However, these environments are very heterogeneous, and high-spatial-resolution data are needed to identify the intra-urban variations of physical parameters. Recently, wearable sensing techniques have been used to perform microscale monitoring, but they usually focus on one environmental physics domain. This paper presents a new wearable system developed to monitor key multidomain parameters related to the air quality, thermal, and visual domains, on a hyperlocal scale from a pedestrian’s perspective. The system consisted of a set of sensors connected to a control unit settled on a backpack and could be connected via Wi-Fi to any portable equipment. The device was prototyped to guarantee the easy sensors maintenance, and a user-friendly dashboard facilitated a real-time monitoring overview. Several tests were conducted to confirm the reliability of the sensors. The new device will allow comprehensive environmental monitoring and multidomain comfort investigations to be carried out, which can support urban planners to face the negative effects of urbanization and to crowd data sourcing in smart cities.

Analysis on the Spatial Variability Mechanism of the Characteristic Water Quality Factors of Urban River Channel Reclaimed Water

Due to the limitations of the treatment process of urban sewage treatment plants and the complexity of water sources, the rich inorganic nitrogen and trace persistent organic matter in the reclaimed water cause potential human health risks through lateral leakage or bioaccumulation during the replenishment process of rivers and lakes. Exploring the distribution law of different types of reclaimed water characteristic water quality factors and their formation in reclaimed water replenishment river channels is of great significance to river and lake management. This study takes the Beijing-Tianjin-Hebei section of the North Canal as the research area and explores the spatial variation characteristics of conventional physical parameters, full index, inorganic nitrogen, and salinity hydronium antibiotics in river water quality with the help of clustering, discrimination, principal components, and variance decomposition. The results showed that, although the spatial distribution patterns of different types of water quality factors were consistent, they all showed significant mid-upstream and downstream distribution; however, there were big differences in the degree of variation and the mechanism of variation. The spatial variation of inorganic nitrogen and antibiotics was the most obvious, whereas the variation in conventional physical parameters and the full index was the weakest, and the salinity hydronium showed moderate variation. The spatial variation mechanism of conventional physical parameters was mainly reflected in microbial degradation. The full index was the result of the combined effect of microorganisms, diffusion, the synergy of the two, and a certain degree of source-sink homogeneity. Diffusion was the main mechanism affecting the spatial variation in salinity hydronium. The spatial variation mechanism of inorganic nitrogen was mainly reflected in the source-sink homogenization and microbial degradation; as a secondary mechanism of the spatial variation of inorganic nitrogen, diffusion had a synergistic mode with microbial degradation. Antibiotics, which have great differences in chemical structural stability and biodegradability, showed high spatial variability and had the highest diffusion and microbial synergy mechanism. This research provides a quantitative analysis of the spatial variability mechanism of water quality based on variance decomposition, which has practical guiding significance for the causes of the spatial variability of river pollutants and river management.

Energy-Efficient Carbon Nanotube Field-Effect Phototransistors: Quantum Simulation, Device Physics, and Photosensitivity Analysis

In this paper, new nanoscale phototransistors based on carbon nanotube (CNT) are proposed and assessed using a quantum simulation-based computational methodology. The used numerical model is based on the self-consistent computation combining the Poisson solver and Schrödinger solver within the non-equilibrium Green’s function (NEGF) formalism while assuming a ballistic transport. The working principle of the proposed phototransistors is based on the light-induced gate photovoltage that alters the electrostatic gating of the transducers as well as the quantum mechanical transport in the zigzag CNT channel. The computational investigation includes two known carbon nanotube field-effect transistors (CNTFET) as photodetector, namely, the MOSFET-like CNTFET and the CNT tunneling FET (CNTTFET). The physics, quantum transport, and photosensitivity behavior of the nanoscale phototransistors were thoroughly investigated including the electron potential distribution, energy-position-resolved current spectrum, drain current, subthreshold swing, sensitivity behavior, and scaling capability. In addition, a parametric investigation was conducted to reveal the photosensitivity trends against the variation in physical and geometrical phototransistors parameters. The obtained results make the investigated CNT-based phototransistors intriguing photodetectors that can serve the cutting-edge nanoscale optoelectronics.

Transient Process Analysis of Multi-Physical Parameters of Turbine Generator During Out of Phase Synchronization Fault

The air-cooled turbo-generator often works in the more frequent start-up and shut-down operation. Either the misoperation or the failure of synchronizing controllers can cause the out of phase synchronization fault. The fault can disturb the power angle and cause a strong impact electromagnetic force for the generator. With the traditional numerical calculation method, it is difficult to calculate the variations of key physical parameters and the electromagnetic field in the end region of the generator under complex working conditions, especially the out of phase synchronization fault. In order to solve the problem, a calculation method of the nonlinear transient electromagnetic field with multi-domain field-circuit-grid coupled is proposed. The correctness of the model and method is validated by comparing the calculated and test values of the magnetic density flux at the key points of the generator under the no-load condition. Based on this method, the power angle variation, the magnetic flux leakage distribution in the end region, and the electromagnetic force on the end winding in the transient process of the fault are calculated and analyzed.

Teratological Evidences in Fish Fauna with reference to Water Quality of Doon Valley, Uttarakhand

Fish fauna of Doon Valley (part of District Dehradun) was explored alongwith 15 physical and chemical water quality parameters. Fish and water sampling was done of five major rivers viz., Baldi, Song and Suswa in the Eastern and Tons and Asan in the Western part of Doon Valley. While doing the taxonomical analysis, four teratological evidence were recorded in the fish species. Teratological manifestation with respect to furcated rostral barbel was observed in one female specimen of Paracanthocobitis botia, furcated maxillary barbel was seen in one specimen of Glyptothorax pectinopterus, forked rostral barbel in Lepidocephalichthys guntea and furcated caudal fin in Heteropneustes fossilis. The fluctuation pattern in water quality all through 3 different seasons reflected an increment pattern from summer to rainy in the parameters like depth, width, water velocity, CO2, turbidity and TDS. The declining trend in the values of the aforesaid parameters was noticed beyond rainy months. From rainy to winters, the increment in values was noticed in DO, pH, hardness, alkalinity, BOD, nitrate and phosphate was observed. The parameters which showed increment in values from winters to summers include AT, WT, CO2. Width, depth and WV have been the chief physical factors with wide range of variations. BOD, Hardness, NO3 TDS, DO and CO2 values seemed more important from the quality of water chemistry point of view. Seasonal variation in physical and chemical parameters have also been observed.

Towards a Monte Carlo simulation of a pebble bed type high temperature gas cooled reactor using Geant4

This paper introduces the stochastic Monte Carlo (MC) modelling of a nuclear reactor core using the Geant4 framework. The simulation is exercised in the context of a High Temperature Gas Cooled Reactor (HTGCR) that uses helium (a noble gas) as a coolant and graphite as a neutron moderator. The study presents the results from the implementation of basic neutronics, scalability, geometrical discretisation for studying the spatial variation of physical parameters, time slicing and adaptation of Geant4 for correct intra-slice persistence, a scheme of integration with thermal hydraulics by workflow scheduling, validation of the thermal macroscopic cross-section behaviour, the process of fission, burn, decay, and differential energy depositions for the various physics processes, validation of the Xenon effects on the neutronics, criticality and core follow over multiple time steps.

Entropy Optimized Second Grade Fluid with MHD and Marangoni Convection Impacts: An Intelligent Neuro-Computing Paradigm

Artificial intelligence applications based on soft computing and machine learning algorithms have recently become the focus of researchers’ attention due to their robustness, precise modeling, simulation, and efficient assessment. The presented work aims to provide an innovative application of Levenberg Marquardt Technique with Artificial Back Propagated Neural Networks (LMT-ABPNN) to examine the entropy generation in Marangoni convection Magnetohydrodynamic Second Grade Fluidic flow model (MHD-SGFM) with Joule heating and dissipation impact. The PDEs describing MHD-SGFM are reduced into ODEs by appropriate transformation. The dataset is determined through Homotopy Analysis Method by the variation of physical parameters for all scenarios of proposed LMT-ABPNN. The reference data samples for training/validation/testing processes are utilized as targets to determine the approximated solution of proposed LMT-ABPNN. The performance of LMT-ABPNN is validated by MSE based fitness, error histogram scrutiny, and regression analysis. Furthermore, the influence of pertinent parameters on temperature, concentration, velocity, entropy generation, and Bejan number is also deliberated. The study reveals that the larger β and Ma, the higher f′(η) while M has the reverse influence on f′(η). For higher values of β, M, Ma, and Ec, θ(η) boosts. The concentration ϕ(η) drops as Ma and Sc grow. An augmentation is noticed for NG for higher estimations of β,M, and Br. Larger β,M and Br decays the Bejan number.

Comparative case study of two methods to assess the eruptive potential of selected active regions

Solar eruptive events, like flares and coronal mass ejections, are characterized by the rapid release of energy that can give rise to emission of radiation across the entire electromagnetic spectrum and to an abrupt significant increase in the kinetic energy of particles. These energetic phenomena can have important effects on the space weather conditions and therefore it is necessary to understand their origin, in particular, what is the eruptive potential of an active region (AR). In these case studies, we compare two distinct methods that were used in previous works to investigate the variations of some characteristic physical parameters during the pre-flare states of flaring ARs. These methods consider: i) the magnetic flux evolution and magnetic helicity accumulation, and ii) the fractal and multi-fractal properties of flux concentrations in ARs. Our comparative analysisis based on time series of photospheric data obtained bythe Solar Dynamics Observatory between March 2011 and June 2013. We selected two distinct samples of ARs: one is distinguished by the occurrence of more energetic M- and X-class flare events, that may have a rapid effect on not just the near-Earth space, but also on the terrestrial environment; the second is characterized by no-flares or having just a few C- and B-class flares. We foundthat the two tested methods complement each other in their ability to assess the eruptive potentials of ARs and could be employed to identify ARs prone to flaring activity. Based on the presented case study, we suggest that using a combination of different methods may aid to identify more reliably the eruptive potentials of ARs and help to better understand the pre-flare states.

The intelligent networks for double-diffusion and MHD analysis of thin film flow over a stretched surface

This study presents a novel application of soft-computing through intelligent, neural networks backpropagated by Levenberg–Marquardt scheme (NNs-BLMS) to solve the mathematical model of unsteady thin film flow of magnetized Maxwell fluid with thermo-diffusion effects and chemical reaction (TFFMFTDECR) over a horizontal rotating disk. The expression for thermophoretic velocity is accounted. Energy expression is deliberated with the addition of non-uniform heat source. The PDEs of mathematical model of TFFMFTDECR are transformed to ODEs by the application of similarity transformations. A dataset is generated through Adams method for the proposed NNs-BLMS in case of various scenarios of TFFMFTDECR model by variation of rotation parameter, magnetic parameter, space dependent heat sink/source parameter, temperature dependent heat sink/source parameter and chemical reaction controlling parameter. The designed computational solver NNs-BLMS is implemented by performing training, testing and validation for the solution of TFFMFTDECR system for different variants. Variation of various physical parameters are designed via plots and explain in details. It is depicted that thin film thickness increases for higher values of disk rotation parameter, while it diminishes for higher magnetic parameter. Furthermore, higher values of Dufour number and the corresponding diminishing values of Soret number causes enhancement in fluid temperature profile. Further the effectiveness of NNs-BLMS is validated by comparing the results of the proposed solver and the standard solution of TFFMFTDECR model through error analyses, histogram representations and regression analyses.

Numerical Study on Heat Transfer Efficiency of Regenerative Thermal Oxidizers with Three Canisters

The heat transfer efficiency of a regenerative thermal oxidizer with three canisters used for volatile organic compounds treatment was studied using numerical simulation methods. A one-dimensional model that took into account the variation of physical parameters with temperature was built. The results show that the preheating temperature and outlet temperature tend to be stable as the operation time is increased. The heat transfer efficiency of equipment was mainly evaluated by heat recovery efficiency and energy recovery ratio under steady state conditions, which was affected by the inlet gas flow and temperature, valve switch time, combustion temperature, materials and porosity of the regenerative medium, and packing height. With the increase in packing cross-sectional area and packing height, the increase in heat transfer efficiency leads to an increase in equipment cost. Simultaneously, the shorter the valve switch time and the higher the density of the regenerative medium battery also help to improve the heat transfer efficiency without blocking equipment. Unless the removal efficiency of volatile organic compound treatment is reduced, it is recommended to reduce the inlet and combustion temperatures.

STUDY ON EFFECT OF PHYSICOCHEMICAL PARAMETERS ON GROWTH OF FUSARIUM EQUISETI (MTCC9658)

The microorganisms like fungi proliferate in different environmental and ecological conditions depending upon the availability of nutrients and the form of nutrient that they absorb. In addition to this the physical conditions like temperature, pH, salinity and light etc. also effect the growth and biomass production of fungal species. The present study was carried out to determine the effect of variation in physical and chemical parameters on growth and biomass production of the fungal strain Fusarium equiseti (MTCC9658). A maximum biomass yield of 12.24 g/L at pH 5 and temperature of 30ºC was recorded; and minimum of 5.21 g/L at pH 9 and temperature of 25ºC.The observations clearly indicate that pH 9 and above did not support higher biomass production at any of the temperatures,while pH 5 to pH 6 supports higher dry biomass production in all temperature ranges applied.The different carbon and nitrogen sources used in the medium corresponded to variation in growth of the strain. Dextrose in combination with Yeast extract as nitrogen source was best for biomass production.

Theoretical analysis of quasi-one-dimensional compressible magnetohydrodynamic channel flow

A theoretical analysis of quasi-one-dimensional, steady, inviscid, compressible channel flow at a low magnetic Reynolds number with variable cross-section is performed in this paper. A second-order nonlinear dynamical system describing the variation of physical parameters is investigated in the phase plane. The characteristics of all possible channel flow with a constant electromagnetic field are obtained by the phase plane and the isomorphism of labeled graphs. It is revealed that the magnetic interaction number novelly derived from the variation rate of the cross-sectional area could significantly affect the phase trajectory in the phase plane of dimensionless velocity and Mach number. Meanwhile, the phase trajectory is only dependent on this magnetic interaction number. Further analysis of the second-order dynamical system discovers five critical values in the range of the magnetic interaction number. These five critical values can divide the whole range into eight subsets under the isomorphism of labeled graphs, forming eight equivalence classes of the phase plane. The study of such eight equivalence classes reveals that the variable cross-section flow in the phase plane can be viewed as a linear superposition of constant cross-section magnetohydrodynamic flow and isentropic flow, the weight ratio being exactly the magnetic interaction number. Consequently, for the divergent channel, the acceleration region in the supersonic zone is larger than that of the constant cross-section flow, while for the convergent channel, only the acceleration region in the subsonic zone is larger than that of the constant cross-section flow.

MHD thin film flow of the Oldroyd-B fluid together with bioconvection and activation energy

The recent study concentrates on the liquid film flow considering Oldroyd-B fluid past a rotating disc in three-dimensional space. The flow pattern has been modeled under the effects of heat absorption/omission and radiation terminologies. The activation energy, bio-convectional, and gyrotactic microorganism phenomena are also included in this study. The Von Karman alterations have been used to alter the basic equations into the set of nonlinear differential equations. The elegant homotopy analysis method (HAM) has been used to obtain the solution of the system of nonlinear differential equations. The influence of the emerging parameters is scrutinized with physical descriptions against the flow pattern, temperature distribution, concentration profile, and gyrotactic microorganism. The detailed outcomes in the heat transfer rate, mass transfer, and motile organism due to the variation of physical parameters have also been shown through bar charts and discussed. It is found that the velocity field decline with the augmentation of magnetic parameter, film thickness parameter, time retardation, and relaxation parameters. The heat transfer enhances with the augmentation of radiation and heat absorption/omission parameters while declining with the Prandtl number. The greater magnitude of the Schmidt number declines the concentration profile.

Clandestine gold mining and pollution risks of sediments from Bagoue river (Niger watershed, Cote d’Ivoire)

Mercury used in gold amalgamation is a global concern and a major source of contamination and dispersion in environmental aquatic of Cote d’Ivoire, mainly in the North where clandestine gold mining activities are a local interest. The aim of this study was to assess the level of total mercury (Hg-T) contamination of sediments from Bagoue River. Water and sediments samples were collected during wet and dry seasons from six stations differently impacted. Spatial and seasonal variations in physical and chemical parameters were assessed. Results revealed that the level of Hg-T in water was 0.68±0.03 µg.L-1 and in the sediments, dry weight concentration was 0.064±0.01 mg.kg-1. The Hg-T concentration in sediments was significantly higher (p< 0.05) during the dry season (0.089±0.053 mg.kg-1) than that recorded in the wet season (0.064±0.039 mg.kg-1). Ultimately, strong and positive correlations have been observed between Hg-T in sediments and sandy sediments (r = +1), as well as suspended materials (r = +0.85). The pollution status of mercury in sediments according to the geo-accumulation index was uncontaminated (- 47.03) at all the seasons whereas enrichment factor has been moderate over climatic seasons at downstream stations heavily impacted by gold mining. The sandy texture of the River sediments favours the infiltration of mercury and its accumulation in groundwater. As a rate, the health risks associated with the consumption of these waters are potentially high.

Spatio-temporal variability of sea-ice and ocean parameters over the Arctic Ocean in response to a warming climate

The fast receding sea-ice extent in the Arctic Ocean (AO) has implications for the global climate. Changes in the sea-ice dynamics cause variations in ocean physical and biogeochemical parameters. An ensemble of simulations from the ‘Community Earth System Model’ (CESM2-WACCM), part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6), is utilized for years 1850–2100. The regional differences in sea-ice parameters are highlighted over seven marginal seas in the AO. The maximum difference in sea-ice heat content (~4.5 × 108 J m−2) is obtained in the East Siberian Sea, central AO, and along the east coast of Greenland in March. The sea surface temperature has higher temporal variability in the Barents Sea, Beaufort Sea and Chukchi Sea in September, which confines the Fram Strait and the Barents Sea regions in March. In September, the sea-ice concentration shows large (>30%) temporal variations in the East Siberian Sea, Laptev Sea, Beaufort Sea, and along the coast of Greenland. Sea surface temperature is projected to increase by 6 °C over the Chukchi Sea by the year 2100. In response to sea-ice melting, a decline in sea-ice thickness and reduction of sea surface salinity up to 2.5 psu is observed in the future relative to the present in some parts of the AO. The advection of Atlantic water and its wind-driven mixing causes maximum winter-time warming in the Svalbard region over the eastern Greenland Sea. The future projections indicate the ice-free surface during September in the AO by the year 2050.

Distributed Optical Fiber Sensing Assisted by Optical Communication Techniques

The development of optical fiber technology has facilitated the technological innovation in optical fiber communication and sensing systems over the past decades. Among all the fiber sensing technologies, distributed optical fiber sensing (DOFS) has attracted great research interests and has been extensively investigated. In optical fiber communication systems, optical parameters such as intensity, phase, polarization, or frequency are modulated to realize data transmission, while for DOFS they are employed to measure the distributed physical parameter variation along the sensing fiber. Due to the similarities shared by optical fiber communication systems and DOFS systems, optical communication techniques, including coherent detection, polarization diversity and multicarrier signaling have been widely used in the DOFS to improve the sensing performance. In this article, principles of coherent detection, polarization diversity and multicarrier signaling are introduced and their applications in phase sensitive optical time domain reflectometry and Brillouin optical time domain analyzer are reviewed. A newly proposed unidirectional forward transmission based DOFS is also presented.

Long-term X-ray observations of seyfert 1 galaxy ark 120: on the origin of soft-excess

ABSTRACT We present the long-term X-ray spectral and temporal analysis of a ‘bare-type AGN’ Ark 120. We consider the observations from XMM–Newton, Suzaku, Swift, and NuSTAR from 2003 to 2018. The spectral properties of this source are studied using various phenomenological and physical models present in the literature. We report (a) the variations of several physical parameters, such as the temperature and the optical depth of the electron cloud, the size of the Compton cloud, and the accretion properties for the last 15 yr. The spectral variations are explained from the changes in the accretion dynamics; (b) the X-ray time delay between 0.2–2 and 3–10 keV light-curves exhibited zero-delay in 2003, positive delay of 4.71 ± 2.1 ks in 2013, and negative delay of 2.90 ± 1.26 ks in 2014. The delays are explained considering Comptonization, reflection, and light-crossing time; (c) the long-term intrinsic luminosities, obtained using nthcomp, of the soft-excess and the primary continuum show a correlation with a Pearson correlation coefficient of 0.90. This indicates that the soft-excess and the primary continuum originate from the same physical process. From a physical model fitting, we infer that the soft excess for Ark 120 could be due to a small number of scatterings in the Compton cloud. Using Monte Carlo simulations, we show that indeed the spectra corresponding to fewer scatterings could provide a steeper soft-excess power law in the 0.2–3 keV range. Simulated luminosities are found to be in agreement with the observed values.