Improving Heat Transfer in Parabolic Trough Solar Collectors by Magnetic Nanofluids

A parabolic trough solar collector(PTSC)converts solar radiation into thermal energy.However,low thermal efficiency of PTSC poses a hindrance to the deployment of solar thermal power plants.Thermal performance of PTSC is enhanced in this study by incorporating magnetic nanoparticles into the working fluid.The circular receiver pipe,with dimensions of 66 mm diameter,2 mm thickness,and 24 m length,is exposed to uniform temperature and velocity conditions.The working fluid,Therminol-66,is supplemented with Fe3O4 magnetic nanoparticles at concentrations ranging from 1%to 4%.The findings demonstrate that the inclusion of nanoparticles increases the convective heat transfer coefficient(HTC)of the PTSC,with higher nanoparticle volume fractions leading to greater heat transfer but increased pressure drop.The thermal enhancement factor(TEF)of the PTSC is positively affected by the volume fraction of nanoparticles,both with and without a magnetic field.Notably,the scenario with a 4%nanoparticle volume fraction and a magnetic field strength of 250 G exhibits the highest TEF,indicating superior thermal performance.These findings offer potential avenues for improving the efficiency of PTSCs in solar thermal plants by introducing magnetic nanoparticles into the working fluid.

Si–Ge based vertical tunnel field-effect transistor of junction-less structure with improved sensitivity using dielectric modulation for biosensing applications

A dielectric modulation strategy for gate oxide material that enhances the sensing performance of biosensors in junction-less vertical tunnel field effect transistors(TFETs)is reported.The junction-less technique,in which metals with specific work functions are deposited on the source region to modulate the channel conductivity,is used to provide the necessary doping for the proper functioning of the device.TCAD simulation studies of the proposed structure and junction structure have been compared,and showed an enhanced rectification of 10^(4) times.The proposed structure is designed to have a nanocavity of length 10 nm on the left-and right-hand sides of the fixed gate dielectric,which improves the biosensor capture area,and hence the sensitivity.By considering neutral and charged biomolecules with different dielectric constants,TCAD simulation studies were compared for their sensitivities.The off-state current IOFFcan be used as a suitable sensing parameter because it has been observed that the proposed sensor exhibits a significant variation in drain current.Additionally,it has been investigated how positively and negatively charged biomolecules affect the drain current and threshold voltage.To explore the device performance when the nanogaps are fully filled,half filled and unevenly filled,extensive TCAD simulations have been run.The proposed TFET structure is further benchmarked to other structures to show its better sensing capabilities.

Experimental and simulation studies on delamination strength of laminated glass composites having polyvinyl butyral and ethyl vinyl acetate inter-layers of different critical thicknesses

The laminated glasses(LGs)composites are gaining popularity as protectivestructural material. Delamination strength(DS) of(LGs) with different inter-layers and their different nominal thicknesses were compared. The effect of inter-layer thickness, delamination load, and inter-layer type on DS is clearly observed from this brief study. It is concluded that inter-layer thickness has the significant role in determining the DS of LGs. The statistical analysis confirmed the strong association of DS with inter-layer thickness and the interlayer type. It was found that the LG-PVB composite has the comparatively lower DS than LG-EVA composite and inter-layer thickness has the prominent role in the determination of DS in the LG-EVAcomposite. There is an increment in DS with an increment in critical inter-layer thickness in both LG-EVA and LG-PVBcomposites. The increment in the inter-layer thickness from 0.38 mm to 0.76 mm increases DS significantly; whereas, the further increment in the inter-layer thickness to the higher value has a lesser effect. The finite element model was constituted(without considering the effect of temperature) for determining DS of LG composite. The simulation results were in a good match with experimental results. The results of the present work can be utilized by the design engineers while selecting LG for structural applications.

Mathematical model of micropolar fluid in two-phase immiscible fluid flow through porous channel

This paper is concerned with the flow of two immiscible fluids through a porous horizontal channel. The fluid in the upper region is the micropolar fluid/the Eringen fluid, and the fluid in the lower region is the Newtonian viscous fluid. The flow is driven by a constant pressure gradient. The presence of micropolar fluids introduces additional rotational parameters. Also, the porous material considered in both regions has two different permeabilities. A direct method is used to obtain the analytical solu- tion of the concerned problem. In the present problem, the effects of the couple stress, the micropolarity parameter, the viscosity ratio, and the permeability on the velocity profile and the microrotational velocity are discussed. It is found that all the physical parameters play an important role in controlling the translational velocity profile and the microrotational velocity. In addition, numerical values of the different flow parameters are computed. The effects of the different flow parameters on the flow rate and the wall shear stress are also discussed graphically.

Life Cycle Energy Analysis of a Multifamily Residential House: A Case Study in Indian Context

The paper presents life cycle energy analysis of a multifamily residential house situated in Allahabad (U.P), India. The study covers energy for construction, operation, maintenance and demolition phases of the building. The selected building is a 4-storey concrete structured multifamily residential house comprising 44 apartments with usable floor area of 2960 m2. The material used for the building structure is steel reinforced concrete and envelope is made up of burnt clay brick masonry. Embodied energy of the building is calculated based on the embodied energy coefficients of building materials applicable in Indian context. Operating energy of the building is estimated using e-Quest energy simulation software. Results show that operating energy (89%) of the building is the largest contributor to life cycle energy of the building, followed by embodied energy (11%). Steel, cement and bricks are most significant materials in terms of contribution to the initial embodied energy profile. The life cycle energy intensity of the building is found to be 75 GJ/m2 and energy index 288 kWh/m2 years (primary). Use of aerated concrete blocks in the construction of walls and for covering roof has been examined as energy saving strategy and it is found that total life cycle energy demand of the building reduces by 9.7%. In addition, building integrated photo voltaic (PV) panels are found most promising for reduction (37%) in life cycle energy (primary) use of the building.

Delay-Dependent Stability Analysis of Discrete Time Delay Systems with Actuator Saturation

This paper focuses on the study and the characterization of stability regions of discrete time systems with a time varying state delay subjected to actuator saturation through anti-windup strategies. Delay-dependent stability conditions are stated in the local as well as global context. An optimization procedure to maximize the estimate of domain of attraction is given. The proposed technique is illustrated by means of numerical examples.

Spectrum handoff scheme with multiple attributes decision making for optimal network selection in cognitive radio networks

It is envisaged that in future Cognitive Radio （CR） networks deployment, multiple radio access networks may coexist. The networks may have different characteristics in terms of multiple attributes. CRs will have choices of selecting the optimal network out of the available networks. Optimal network selection is a challenging task that can be performed by spectrum handoff with Multiple Attribute Decision Making （MADM）. The spectrum handoff decision with MADM provides wider and optimal choice with quality of service. This motivates the development of a spectrum handoff scheme with MADM methods such as simple additive weighting, a technique for order preference by similarity to the ideal solution, a grey relational analysis and a cost function based method, which is the objective of this study. The CR preferences are based on voice, video and data services, called triple play services. The numerical results show that all MADM methods are effective for selecting the optimal network for spectrum handoff with a reduced complexity for the spectrum handoff decision. The paper shows that the proposed spectrum handoff scheme can be effectively implemented to select the optimal network according to triple play services in CR networks.

Free Vibration Analysis of RC Box-Girder Bridges Using FEM

The free vibration analysis of simply supported box-girder bridges is carried out using the finite element method.The fundamental frequency is determined in straight,skew,curved and skew-curved box-girder bridges.It is important to analyse the combined effect of skewness and curvature because skew-curved box-girder bridge behaviour cannot be predicted by simply adding the individual effects of skewness and curvature.At first,an existing model is considered to validate the present approach.A convergence study is carried out to decide the mesh size in the finite element method.An exhaustive parametric study is conducted to determine the fundamental frequency of box-girder bridges with varying skew angle,curve angle,span,span-depth ratio and cell number.The skew angle is varied from 0°to 60°,curve angle is varied from 0°to 60°,span is changed from 25 to 50 m,span-depth ratio is varied from 10 to 16,and single cell&double cell are used in the present study.A total of 420 bridge models are used for parametric study in the investigation.Mode shapes of the skew-curved bridge are also presented.The fundamental frequency of the skew-curved box-girder bridge is found to be more than the straight bridge,so,the skew-curved box-girder bridge is preferable.The present study may be useful in the design of box-girder bridges.

Frequencies of Lock Gate Structure Coupled with Reservoir Fluid

This study determines the natural frequencies of the lock gate structure,considering the coupled effect of reservoir fluid on one side using the finite element method(FEM).The gate is assumed to be a uniformly thick plate,and its material is isotropic,homogeneous,and elastic.The reservoir fluid is assumed to be inviscid and incompressible in an irrotational flow field.The length of the reservoir domain is truncated using the far boundary condition by adopting the Fourier series expansion theory.Two different assumptions on the free surface,i.e.,undisturbed and linearized,are considered in the fluid domain analysis.The computer code is written based on the developed finite element formulations.The natural frequencies of the lock gate are computed when interacting with and without reservoir fluid.Several numerical problems are studied considering the effects of boundary conditions,aspect ratios,and varying dimensions of the gate and the fluid domain.The frequencies of gate reduce significantly due to the presence of fluid.The frequencies increase when the fluid extends to either side of the gate.The frequencies reduce when the depth of the fluid domain above the top edge of the gate increases.The frequencies drop considerably when the free surface condition is taken into account.The results of frequencies of lock gate structure may be useful to the designer if it is experienced in natural catastrophes.

Ply-by-Ply Failure Analysis of Laminates under Dynamic Loading

Ply-by-ply failure analysis of symmetric and anti-symmetric laminates under uniform sinusoidal transverse dynamic loading is performed for a specified duration.The study investigates the first ply failure load,followed by the detection of successive ply failures and their failure modes using various failure theories.Some of the well-established failure theories,mostly used by the researchers,are considered for the failure prediction in laminates.The finite element computational model based on higher order shear deformation displacement field is used for the failure analysis and the complete methodology is computer coded using FORTRAN.The ply-discount stiffness reduction scheme is employed to modify the material properties of the failed lamina.The failure theories used in the analysis are compared according to their ability to predict failure load,failed ply,failure mode and progression of failure.The failure analysis is performed for both the cross-ply and angle-ply laminates with all edges simply supported and clamped.The significance of fibre orientation and stacking sequence in terms of the strength of a laminate and failure progression is also highlighted.

Coordination of Overcurrent Relay in Distributed System for Different Network Configuration

This paper presents a study on protection coordination of over current relays (OCRs) in a distributed system by considering its different operating modes. Two different case studies which are considered in present work for protection coordination include: (i) DG interfaced distribution system in grid connected mode and (ii) DG interfaced distribution system in islanded mode of operation. The proposed approach is tested on the Canadian urban benchmark distribution system consisting of 9 buses. On the occurrence of fault, level of fault current changes which in turn changes the operating time of various OCRs. Therefore, it is important to calculate and suggest method of the relay setting in order to minimize the operating time of relays and also to avoid its mal-operation. In this paper, the protection scheme is optimally designed by taking into account the above mentioned conditions. The operating time of relays can be decreased and, at the same time, coordination can be maintained by considering the optimum values of time dial setting (TDS). Genetic Algorithm (GA) has been used for determining the optimum values of TDS and hence operating time.

A Review of Price Forecasting Problem and Techniques in Deregulated Electricity Markets

In deregulated electricity markets, price forecasting is gaining importance between various market players in the power in order to adjust their bids in the day-ahead electricity markets and maximize their profits. Electricity price is volatile but non random in nature making it possible to identify the patterns based on the historical data and forecast. An accurate price forecasting method is an important factor for the market players as it enables them to decide their bidding strategy to maximize profits. Various models have been developed over a period of time which can be broadly classified into two types of models that are mainly used for Electricity Price forecasting are: 1) Time series models;and 2) Simulation based models;time series models are widely used among the two, for day ahead forecasting. The presented work summarizes the influencing factors that affect the price behavior and various established forecasting models based on time series analysis, such as Linear regression based models, nonlinear heuristics based models and other simulation based models.

Simulation &Performance Evaluation of QoS Routing Protocol for Adhoc Networks Using Directional Communication

A wireless ad-hoc network is a self-organized wireless network without fixed or backbone infrastructure. All nodes have routing capability and use peer-to-peer packet transmission or forward packets to other node using multi hop communication. Now days mobile ad-hoc networks are being used for different applications and traffics, so it require quality of service (QoS) support in routing protocol. In this paper, a modified QoS routing protocol using directional antenna has been proposed. High and normal priority can be assigned based on type of traffic. All the nodes in the path used by high priority flow are reserved as high priority flow for that flow and normal priority flow will avoid the paths used by high priority flows. If no disjoint paths are available, there may be two possibilities: Normal priority flows are blocked and other is, normal priority flows are allow using the coupled path with high priority flow. Blocking the normal priority flow, QoS routing protocol improves the performance of high priority flow. This concept may be use in emergency communication. Simulation results show that by assigning the priorities to flows, performance of high priority flows are improved and it will further improved by blocking the normal priority flow.

Soft Handover Probability Determination Considering New Direction of Motion

This paper presents prior determination of soft handover probability considering new direction of motion of mobile station (MS) coinciding with gravitation point of cells. Our simulation results for 3-cell scenario and considered new direction of MS motion can be potentially used as advance input to soft handover algorithms to minimize number of handovers.

Impact of Industrial Symbiosis on Sustainability

This paper quantitatively examines the impact of industrial symbiosis on sustainability. The quantitative approach, as developed by the authors, is based on the concept of Industrial Sustainability Index (ISI), which represents the socio-economic benefit of an industry per unit of its carbon emissions. The ISI was evaluated for a chemical production plant both in independent and symbiotic modes with different energy technologies. The ISI value for the chemical production plant in independent mode was found to be 6 units. This was three times more than in the case of the existing symbiotic mode with an adjacent pulp & paper industry having coal fired CHP plant. With the adoption of more energy efficient technologies e.g. natural gas based combined cycle power plant and solar PV electricity generation;the ISI in the modified symbiotic mode can be increased to 18 units. The results indicate that industrial symbiosis can help in sustainability improvement when the technologies used by the industries are energy efficient.

Life Cycle Energy of Low Rise Residential Buildings in Indian Context

Life cycle energy of the building accounts for all energy inputs to the buildings during their intended service life. Buildings need to be constructed in such a way that energy consumption in their life cycle is minimal. Life Cycle Energy (LCE) consumption data of buildings is not available in public domain which is essentially required for building designers and policy makers to formulate strategies for reduction in LCE of buildings. The paper presents LCE of twenty (20) low rise residential buildings in Indian context. LCE of the studied buildings is varying from 160 - 380 kWh/m2 year (Primary). Based on the LCE data of studied buildings, an equation is proposed to readily reckon LCE of a new building.

Transient Combined Convective Heat Transfer over a Stretching Surface in a Non-Newtonian Nanofluid Using Buongiorno’s Model

The present paper investigates the transient mixed convective boundary layer flow of an incompressible non-Newtonian quiescent nanofluid adjacent to a vertical stretching surface. The effects of the Brownian motion and thermophoresis are included for the nanofluid. Using appropriate non-similarity transformations the non-dimensional, coupled and highly non-linear system of equations is solved numerically using the efficient Keller-box implicit finite difference method for the whole transient from t=0 (initial state) to (final steady-state flow). The box method is unconditionally stable. Numerical results for dimensionless velocity (f’), micro-rotation (g), temperature (θ), nanoparticle volume fraction (Φ) at final steady state flow, skin friction function (), Nusselt number function () and Sherwood number function () have been presented on various parameters inform of tables and graphs. The results indicate that as Nb and Nt increase, the Nusselt number decreases whereas Sherwood number increases at initial and early state time but decreases at the final steady state time. As the K increases, the friction factor decreases whereas surface mass transfer rate and the surface heat transfer rates slightly increase. The results reveal that there is a smooth transition of flow from unsteady state to the final steady state. A special case of our results is in good agreement with an earlier published work. The study has many practical applications such as extrusion of plastic sheets, paper production, glass blowing, metal spinning and drawing plastic films.

Effect of Digital and Financial Awareness of Household Womens on the Use of Fin-Tech in India: Observing the Relation with (Utaut) Model

Era of COVID-19 resulted in contactless transactions and extensive use of technological applications.Similar was the case of Fin-Tech which has extensively been used by consumers all around the globe for making transactions and other financial and economic needs.Although there is a lack of research to reflect these forms of evidence from the developing as well as Indian sides of the globe.On the other side,some studies indicated the Unified Household Acceptance and Use of Technology(UTAUT)model as the base to prefer mobile methods of transaction and Fin-Tech use.Hence this paper has been developed systematically to relate the financial literacy of household females from Generation Y with the use of Fin-Tech during the eve of COVID-19.For devising this relationship research has been induced with the UTAUT model and data have been collected from married household females between twenty-four to thirty-five years of age.Results were analyzed through SMART-PLS which highlighted the financial literacy of Indian household females has a significant association with UTAUT model.However,the entire UTAUT model does not have a significant relationship with the use of Fin-Tech.

Physical Parameter Variation Analysis on the Performance Characteristics of Nano DG-MOSFETs

DG-MOSFETs are the most widely explored device architectures for nano-scale CMOS circuit design in sub-50 nm due to the improved subthreshold slope and the reduced leakage power compared to bulk MOSFETs. In thin-film (tsi < 10 nm) DG-MOS structures, charge carriers are affected by tsi- induced quantum confinement along with the confinement caused by a very high electric field at the interface. Therefore, quantum confinement effects on the device characteristics are also quite important and it needs to be incorporated along with short channel effects for nano-scale circuit design. In this paper, we analyzed a DG-MOSFET structure at the 20 nm technology node incorporating quantum confinement effects and various short channel effects. The effect of physical parameter variations on performance characteristics of the device such as threshold voltage, subthreshold slope, ION - IOFF ratio, DIBL, etc. has been investigated and plotted through extensive TCAD simulations. The physical parameters considered in this paper are operating temperature (Top), channel doping concentration (Nc), gate oxide thickness (tox) and Silicon film thickness (tsi). It was observed that quantum confinement of charge carriers significantly affected the performance characteristics (mostly the subthreshold characteristics) of the device and therefore, it cannot be ignored in the subthreshold region-based circuit design like in many previous research works. The ATLASTM device simulator has been used in this paper to perform simulation and parameter extraction. The TCAD analysis presented in the manuscript can be incorporated for device modeling and device matching. It can be used to illustrate exact device behavior and for proper device control.

Real Time Implementation of Series Expansion Based Digital Controller for Magnetic Levitation System

This paper addresses a digital controller for a real time magnetic levitation system using series expansion of pulse transfer function, which achieves desired closed loop response. The proposed digital controller designed, based on series expansion of pulse transfer function by solving a linear equation using the method of least squares, which improves the transient performance and step tracking capability of the compensated system. The designed algorithm used for the control input is not iterative, so the calculation is very fast. The proposed control scheme has successfully applied on maglev system and also validated through the simulation and hardware experimental results.