The three-dimensional numerical investigation of an incompressible flow through rib roughened solar air heater is carried out.A combination of thin transverse and truncated ribs is attached on the absorber plate to st...The three-dimensional numerical investigation of an incompressible flow through rib roughened solar air heater is carried out.A combination of thin transverse and truncated ribs is attached on the absorber plate to study its effect on the heat transfer and friction factor.The parameters in the form of Reynolds number(Re)of 4000-16000,relative roughness pitch(P/e)of 8-18 and relative roughness height(e/Dh)of 0.0366-0.055 is considered for the analysis.The CFD code ANSYS FLUENT is used to solve the governing equations of turbulent flow.The RNG k-εturbulence model is used to solve the transport equations with enhanced wall treatment,keeping the Y+<1.The maximum enhancement ratio of the Nusselt number and friction factor obtained is 1.91 and 3.61 respectively.The detailed investigation on average heat transfer,friction factor and flow structures have been discussed.展开更多
Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytot...Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride(TCH) over a metal-free 8-hydroxyquinoline(8-HQ) functionalized carbon nitride(CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth.This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.展开更多
In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Micros...In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Microstructural observations showed that the thickness of the produced composite layer was in the range of 2500μm.FSP resulted uniform distribution of CNT near the surface while agglomerated layers in the subsurface.Grain refinement of Mg achieved by FSP improved the hardness but significant enhancement in the hardness value was observed for FSPed MWCNT/Mg composites.Potentiodynamic polarization studies revealed that the increase in corrosion current density was observed for MWCNT/Mg composite compared with grain refined Mg and pure Mg,implying the significance of secondary phase(MWCNT)in decreasing the corrosion resistance of the composite.展开更多
Sheet-metal products are integral parts of engineering industries and academia research. Various testing techniques have revealed the deformation behaviors of sheet metals under complex stress states. Information obta...Sheet-metal products are integral parts of engineering industries and academia research. Various testing techniques have revealed the deformation behaviors of sheet metals under complex stress states. Information obtained from tensile and compression tests, however, are insufficient for the identification of material parameters relevant to modern constitutive laws, which require experimental setups capable of generating various loading conditions and applying great amounts of strain to sheet metals. In-plane shear testing has emerged as an important method to overcome the challenges associated with tension and compression tests and can provide additional information about deformation behaviors under large plastic strains. Materials such as Mg alloys with poor levels of both ductility and formability cannot accommodate large plastic strains. Therefore, tension and compression tests have limitations in explaining the material behaviors that occur during sheet metal forming where large plastic strains are introduced. Many studies have been conducted to explain the deformation behaviors of Mg alloys under shear deformation techniques. These include severe plastic deformation(SPD), especially the equal channel angular pressing(ECAP)and equal channel angular extrusion, rolling combined with shear deformation i.e. differential speed rolling(DSR), and also in-plane shear for sheet metals, particularly under large levels of plastic strain. These in-plane shear technique involves the Miyauchi shear test, ASTM shear test, and twin bridge shear tests. Moreover, many experimental results have revealed that the evolution of microstructure and texture during in-plane shear is closely related to the failure behavior of materials. Therefore, this review is focused on techniques for in-plane shear testing that have been reported thus far, on the effect of in-plane shear on the microstructure development of Mg alloy sheets, and on the usefulness of in-plane shear testing to evaluate the formability of Mg alloy sheets.展开更多
Wind energy （WE） has become immensely popular for distributed generation （DG）. This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric ...Wind energy （WE） has become immensely popular for distributed generation （DG）. This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric grid interfacing custom power device （CPD） is controlled to perform the smart exchanging of electric power as per the Indian grid code. WE is connected to DC link of CPD for the grid integration purpose. The CPD based distributed static compensator, i.e. the distributed static synchronous compensator （DSTATCOM）, is utilized for injecting the wind power to the point of common coupling （PCC） and also acts against the reactive power demand. The novel indirect current control scheme of DSTATCOM regulates the power import and export between the WE and the electric grid system. It also acts as a compensator and performs both the key features simultaneously. Hence, the penetration of additional generated WE power to the grid is increased by 20% to 25%. The burden of reactive power compensation from grid is reduced by DSTATCOM. The modeling and simulation are done in MATLAB. The results are validated and verified.展开更多
Dental crowns are best utilized as a way to improve the cosmetics of a tooth appearance when the crown simultaneously serves other purposes also, such as restoring a tooth to its original shape or strengthening a toot...Dental crowns are best utilized as a way to improve the cosmetics of a tooth appearance when the crown simultaneously serves other purposes also, such as restoring a tooth to its original shape or strengthening a tooth. The study presents four different designs of molar crown depending upon the tooth loss. The finite element results obtained suggests that restored material which fills the treated cavity along with small portion of root canal can help in retaining the restored tooth and can allow larger deformations for stresses induced well within the limit.展开更多
Natural disasters not only result in financial loss but also the human lives. The failure of the existing buildings is one of the primary concerns for the damage to human lives. In order to plan a disaster free city p...Natural disasters not only result in financial loss but also the human lives. The failure of the existing buildings is one of the primary concerns for the damage to human lives. In order to plan a disaster free city proper planning of the buildings ＆ infrastructure along with the associated information of non-spatial attributes are needed. The present paper highlights the application of satellite imagery for feature extraction and storing the associated database in GIS environment which is useful for decision making in real time disaster management. The complete methodology is elaborated with the help of a case study for earthquake risk assessment of Maharashtra Industrial Development Corporation （MIDC）, Akola, Maharashtra, India region. For the better and precise work 0.5 m. resolution imagery is utilized for extracting the buildings ＆ other infrastructure features. The structural and non-structural details of the buildings are stored as back end for possible vulnerability assessment, suitable planning and preparedness against the hazard. The extracted building features in the planned area have been given suitable weightages for Vulnerability Indexing. Based on suggested indexing approach possible retrofitting measures from the developed database can be recommended for the existing buildings in the proposed location of research. The proposed approach can further be extended for the entire infrastructure of the nation where the centralized data can be made available with Emergency Operation Centre for further planning ＆ preparedness to make the nation disaster free.展开更多
This paper deals with study of generalized Chaplygin gas model with dynamical gravitational and cosmological constants. In this paper a new set of exact solutions of Einstein field equations for spatially homogeneous ...This paper deals with study of generalized Chaplygin gas model with dynamical gravitational and cosmological constants. In this paper a new set of exact solutions of Einstein field equations for spatially homogeneous and anisotropic Bianchi type Ⅰ space-time have been obtained. The solutions of the Einstein's field equations are obtained by considering(i) the power law relation between Hubble parameter H and scale factor R and(ii) scale factor of the form R =-1/t + t^2, t > 1. The assumptions lead to constant and variable deceleration parameter respectively. The physical and dynamical behaviors of the models have been discussed with the help of graphical representations. Also we have discussed the stability and physical acceptability of solutions for solution type-Ⅰ and solution type-Ⅱ.展开更多
The present paper addresses the comparative study of three adjacent single-degree-of freedom structures for elastic and inelastic system with and without pounding under seismic excitations. For the gap between three a...The present paper addresses the comparative study of three adjacent single-degree-of freedom structures for elastic and inelastic system with and without pounding under seismic excitations. For the gap between three adjacent structures, the simulation is done by using linear spring element without damping. The entire numerical simulation is done in time domain by considering the inputs of four real ground motions. The results of the study show that the response of elastic system is much different to that of response of inelastic system in the absence and presence of pounding, especially in lighter or more flexible structures. Elastic structures show much severe pounding response than inelastic structures. Modeling of colliding structures behaving inelastically is really needed in order to obtain the accurate structural pounding involved response under seismic excitation.展开更多
In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was performed.The ConWep program,developed by the US A...In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was performed.The ConWep program,developed by the US Army,was used to simulate blast loading using ABAQUS/Explicit■.Drucker-Prager(D-P)plasticity model,concrete damage plasticity(CDP),and Johnson-Cook(J-C)plasticity models were used to define the behavior of the soil,concrete,and reinforcement,respectively.FE analysis was carried out to compare the damages to the superstructure with variation in the cross-sectional shapes of the tunnel under internal blast loading.Three tunnel shapes(circular,rectangular,and horseshoe cross-sections)were considered in the FE analysis.An explosive of 100 kg TNT was located at the center of the cross-section of the tunnel.The response of the tunnel in terms of displacement and stress at critical locations was computed.The results showed that changes in the cross-section of the tunnel affect the stability of the tunnel,even when keeping all other factors constant.It was observed that the intensity of the stresses was the highest for a rectangular tunnel and lowest for a circular tunnel.Furthermore,it was also determined that the tunnel with a rectangular cross-section experienced the maximum displacement in the reinforced concrete(RC)lining compared with the horseshoe and circular tunnels.The displacement measured at critical structural members of the superstructure was found to be the highest for the tunnel with a rectangular cross-section and lowest for the tunnel with a circular cross-section.展开更多
文摘The three-dimensional numerical investigation of an incompressible flow through rib roughened solar air heater is carried out.A combination of thin transverse and truncated ribs is attached on the absorber plate to study its effect on the heat transfer and friction factor.The parameters in the form of Reynolds number(Re)of 4000-16000,relative roughness pitch(P/e)of 8-18 and relative roughness height(e/Dh)of 0.0366-0.055 is considered for the analysis.The CFD code ANSYS FLUENT is used to solve the governing equations of turbulent flow.The RNG k-εturbulence model is used to solve the transport equations with enhanced wall treatment,keeping the Y+<1.The maximum enhancement ratio of the Nusselt number and friction factor obtained is 1.91 and 3.61 respectively.The detailed investigation on average heat transfer,friction factor and flow structures have been discussed.
基金the department of science and technology fund for improvement of science and technology infrastructure (DST FIST) (No. SR/FST/CSI-279/2016(C)) for providing XRD and UV-DRS facilitiesthe department of science and technology science and engineering research board (DST-SERB) through the project (No. SB/EMEQ-052/2014 SERB) for financial assistancethe Director, Visvesvaraya National Institute of Technology (VNIT) Nagpur for financial support。
文摘Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride(TCH) over a metal-free 8-hydroxyquinoline(8-HQ) functionalized carbon nitride(CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth.This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.
文摘In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Microstructural observations showed that the thickness of the produced composite layer was in the range of 2500μm.FSP resulted uniform distribution of CNT near the surface while agglomerated layers in the subsurface.Grain refinement of Mg achieved by FSP improved the hardness but significant enhancement in the hardness value was observed for FSPed MWCNT/Mg composites.Potentiodynamic polarization studies revealed that the increase in corrosion current density was observed for MWCNT/Mg composite compared with grain refined Mg and pure Mg,implying the significance of secondary phase(MWCNT)in decreasing the corrosion resistance of the composite.
基金financially supported by the Science and Engineering Research Board (SERB)a statutory body of the Department of Science&Technology (DST)+1 种基金Government of India through the Start-up Research Grant (SRG) scheme (File No. SRG/2020/000341)National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT)(NRF-2020R1A2C1010134)。
文摘Sheet-metal products are integral parts of engineering industries and academia research. Various testing techniques have revealed the deformation behaviors of sheet metals under complex stress states. Information obtained from tensile and compression tests, however, are insufficient for the identification of material parameters relevant to modern constitutive laws, which require experimental setups capable of generating various loading conditions and applying great amounts of strain to sheet metals. In-plane shear testing has emerged as an important method to overcome the challenges associated with tension and compression tests and can provide additional information about deformation behaviors under large plastic strains. Materials such as Mg alloys with poor levels of both ductility and formability cannot accommodate large plastic strains. Therefore, tension and compression tests have limitations in explaining the material behaviors that occur during sheet metal forming where large plastic strains are introduced. Many studies have been conducted to explain the deformation behaviors of Mg alloys under shear deformation techniques. These include severe plastic deformation(SPD), especially the equal channel angular pressing(ECAP)and equal channel angular extrusion, rolling combined with shear deformation i.e. differential speed rolling(DSR), and also in-plane shear for sheet metals, particularly under large levels of plastic strain. These in-plane shear technique involves the Miyauchi shear test, ASTM shear test, and twin bridge shear tests. Moreover, many experimental results have revealed that the evolution of microstructure and texture during in-plane shear is closely related to the failure behavior of materials. Therefore, this review is focused on techniques for in-plane shear testing that have been reported thus far, on the effect of in-plane shear on the microstructure development of Mg alloy sheets, and on the usefulness of in-plane shear testing to evaluate the formability of Mg alloy sheets.
文摘Wind energy （WE） has become immensely popular for distributed generation （DG）. This case presents the monitoring, modeling, control, and analysis of the two-level three-phase WE based DG system where the electric grid interfacing custom power device （CPD） is controlled to perform the smart exchanging of electric power as per the Indian grid code. WE is connected to DC link of CPD for the grid integration purpose. The CPD based distributed static compensator, i.e. the distributed static synchronous compensator （DSTATCOM）, is utilized for injecting the wind power to the point of common coupling （PCC） and also acts against the reactive power demand. The novel indirect current control scheme of DSTATCOM regulates the power import and export between the WE and the electric grid system. It also acts as a compensator and performs both the key features simultaneously. Hence, the penetration of additional generated WE power to the grid is increased by 20% to 25%. The burden of reactive power compensation from grid is reduced by DSTATCOM. The modeling and simulation are done in MATLAB. The results are validated and verified.
文摘Dental crowns are best utilized as a way to improve the cosmetics of a tooth appearance when the crown simultaneously serves other purposes also, such as restoring a tooth to its original shape or strengthening a tooth. The study presents four different designs of molar crown depending upon the tooth loss. The finite element results obtained suggests that restored material which fills the treated cavity along with small portion of root canal can help in retaining the restored tooth and can allow larger deformations for stresses induced well within the limit.
文摘Natural disasters not only result in financial loss but also the human lives. The failure of the existing buildings is one of the primary concerns for the damage to human lives. In order to plan a disaster free city proper planning of the buildings ＆ infrastructure along with the associated information of non-spatial attributes are needed. The present paper highlights the application of satellite imagery for feature extraction and storing the associated database in GIS environment which is useful for decision making in real time disaster management. The complete methodology is elaborated with the help of a case study for earthquake risk assessment of Maharashtra Industrial Development Corporation （MIDC）, Akola, Maharashtra, India region. For the better and precise work 0.5 m. resolution imagery is utilized for extracting the buildings ＆ other infrastructure features. The structural and non-structural details of the buildings are stored as back end for possible vulnerability assessment, suitable planning and preparedness against the hazard. The extracted building features in the planned area have been given suitable weightages for Vulnerability Indexing. Based on suggested indexing approach possible retrofitting measures from the developed database can be recommended for the existing buildings in the proposed location of research. The proposed approach can further be extended for the entire infrastructure of the nation where the centralized data can be made available with Emergency Operation Centre for further planning ＆ preparedness to make the nation disaster free.
文摘This paper deals with study of generalized Chaplygin gas model with dynamical gravitational and cosmological constants. In this paper a new set of exact solutions of Einstein field equations for spatially homogeneous and anisotropic Bianchi type Ⅰ space-time have been obtained. The solutions of the Einstein's field equations are obtained by considering(i) the power law relation between Hubble parameter H and scale factor R and(ii) scale factor of the form R =-1/t + t^2, t > 1. The assumptions lead to constant and variable deceleration parameter respectively. The physical and dynamical behaviors of the models have been discussed with the help of graphical representations. Also we have discussed the stability and physical acceptability of solutions for solution type-Ⅰ and solution type-Ⅱ.
文摘The present paper addresses the comparative study of three adjacent single-degree-of freedom structures for elastic and inelastic system with and without pounding under seismic excitations. For the gap between three adjacent structures, the simulation is done by using linear spring element without damping. The entire numerical simulation is done in time domain by considering the inputs of four real ground motions. The results of the study show that the response of elastic system is much different to that of response of inelastic system in the absence and presence of pounding, especially in lighter or more flexible structures. Elastic structures show much severe pounding response than inelastic structures. Modeling of colliding structures behaving inelastically is really needed in order to obtain the accurate structural pounding involved response under seismic excitation.
文摘In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was performed.The ConWep program,developed by the US Army,was used to simulate blast loading using ABAQUS/Explicit■.Drucker-Prager(D-P)plasticity model,concrete damage plasticity(CDP),and Johnson-Cook(J-C)plasticity models were used to define the behavior of the soil,concrete,and reinforcement,respectively.FE analysis was carried out to compare the damages to the superstructure with variation in the cross-sectional shapes of the tunnel under internal blast loading.Three tunnel shapes(circular,rectangular,and horseshoe cross-sections)were considered in the FE analysis.An explosive of 100 kg TNT was located at the center of the cross-section of the tunnel.The response of the tunnel in terms of displacement and stress at critical locations was computed.The results showed that changes in the cross-section of the tunnel affect the stability of the tunnel,even when keeping all other factors constant.It was observed that the intensity of the stresses was the highest for a rectangular tunnel and lowest for a circular tunnel.Furthermore,it was also determined that the tunnel with a rectangular cross-section experienced the maximum displacement in the reinforced concrete(RC)lining compared with the horseshoe and circular tunnels.The displacement measured at critical structural members of the superstructure was found to be the highest for the tunnel with a rectangular cross-section and lowest for the tunnel with a circular cross-section.
