Most of the investigations regarding friction stir welding(FSW)of aluminum alloy plates have been limited to about 5 to 6mm thick plates.In prior work conducted the various aspects concerning the process parameters an...Most of the investigations regarding friction stir welding(FSW)of aluminum alloy plates have been limited to about 5 to 6mm thick plates.In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy.Two different simple-tomanufacture tool geometries were used.The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined.It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates,tool having trapezoidal pin geometry was suitable.Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min.At very low and high dwell time the ductility of welded joints are reduced significantly.展开更多
Wetlands are those landscapes which are saturated with water or covered by water either perennially or for a major part of the year. Due to transforming nature of the wetlands from aquatic to terrestrial, the related ...Wetlands are those landscapes which are saturated with water or covered by water either perennially or for a major part of the year. Due to transforming nature of the wetlands from aquatic to terrestrial, the related physical features are not easy to be monitored. With the recent advancement in Remote sensing technique, the feature extraction of wetland with the help of different satellite derived band algebras including Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Modified NDWI (MNDWI), Normalized Difference Moisture Index (NDMI) is being used by experts. The common diagnostic features of wetlands are surface water, swamps and aquatic vegetation. The present study is based on a comparison between these four indices. Baraila wetland of Vaishali district Bihar is selected as a site for the study because the surface water of this “BAT” shaped wetland has decreased rapidly in last half decade which is alarming for the related ecology and biodiversity.展开更多
An electronic circuit has been designed to mimic glycolysis, the Citric Acid (TCA) cycle and the electron transport chain. Enzymes play a vital role in metabolic pathways; similarly transistors play a vital role in e...An electronic circuit has been designed to mimic glycolysis, the Citric Acid (TCA) cycle and the electron transport chain. Enzymes play a vital role in metabolic pathways; similarly transistors play a vital role in electronic circuits; the characteristics of enzymes in comparison with those of transistors suggests that the properties are analagous. Enzymes possess an active site into which the substrate binds, similarly the transistor possess a layer in which the recombination of holes and electrons takes place. Hence the applied voltage in the circuit is considered as the substrate. The enthalpy values of the enzymes are converted into volts, which is to be applied to the circuit. ATP is the energy source in the metabolic pathway which functions like a potential in the electronic circuit. Some enzymes can function only with the help of a cofactor; here modelled as a switch. Using all the above electronic circuit analogues, which possess the similar characteristics of the metabolic pathway constituents, circuits have been designed.展开更多
This paper analyzes and compares the performance of a new inverter topology with two types of input sources: 1) Solar PV source and 2) Ideal dc source (battery). The simulation is done in SIMULINK/MATLAB Software. It ...This paper analyzes and compares the performance of a new inverter topology with two types of input sources: 1) Solar PV source and 2) Ideal dc source (battery). The simulation is done in SIMULINK/MATLAB Software. It is shown that when the solar panel is connected, spikes are obtained in output voltage waveforms. These spikes are eliminated by inserting a capacitor. The capacitor is chosen for a particular power factor which is optimum with respect to cost, size and power quality. Total Harmonic Distortion, Active Power, Reactive Power, RMS Voltage and RMS Current are measured for different load power factor. Finally these results are compared with those obtained using battery with same input voltage magnitude. This Paper shows that for Solar Panel Circuit, THD, P and Q are less for 0.8 and above power factor, however below 0.8 PF, the THD, active and reactive power transfer are more. This means that the performance of Solar Panel in the proposed circuit topology is seen to be better as compared to the same circuit with battery within a range of power factor.展开更多
The experimental results which were carried out by different researchers on corrosion of RCC beam were validated in ABAQUS. A finite element (FE) model similar to experimental condition was generated in ABAQUS. The mo...The experimental results which were carried out by different researchers on corrosion of RCC beam were validated in ABAQUS. A finite element (FE) model similar to experimental condition was generated in ABAQUS. The model with different percentages of corrosion and with varying load conditions was also generated. The deflections of RCC beam for different corrosion percentages and for varying load conditions were then validated. The model is then used to explore the effects of bar radial expansion, due to formation of corrosion products, on the cracking of cover concrete. The predictions are compared with tests results from reinforced concrete accelerated corrosion specimens. The aim of the analytical investigation was to reveal the mechanism for the development of concrete cracking due to corrosion of reinforcement. Further the finite element model will be used to explain qualitatively the experimentally determined relationship between amount of corrosion for concrete cracking and ratio of concrete cover to bar diameter, as well as that between reinforcement bond strength and amount of corrosion.展开更多
Local scour is the reduction of original bed level around any hydraulic structure.Bridge failure due to scouring has made researchers study the cause of scouring and predict the scour depth and pattern around bridge p...Local scour is the reduction of original bed level around any hydraulic structure.Bridge failure due to scouring has made researchers study the cause of scouring and predict the scour depth and pattern around bridge piers and foundations.Several investigators have extensively studied local scour around isolated bridge pier,but modern designs of the bridges comprise of wide span and thus group of piers rather than a single pier.The flow and scour pattern around group of piers are different from the case of a single pier due to the interaction effect.The objective of present study is to investigate the effect of mutual interference of bridge piers on local scour experimentally around two piers in non-cohesive bed.Experiments were carried out on model bridge piers of circular cross section in a meandering channel.It was observed that when front and rear piers were placed at an angular displacement ofθ=40°and 80°respectively,maximum depth of scour is maximum.Hereθis the angle the line drawn at the inlet of bend to the line joining the centre of curvature and any point on the outer portion of the bend.展开更多
In today’s rapidly urbanizing world,there is dire need for adopting the principles of green/sustainable built-environment so as to mitigate the ill effects of environmental degradation and climate change.However,dema...In today’s rapidly urbanizing world,there is dire need for adopting the principles of green/sustainable built-environment so as to mitigate the ill effects of environmental degradation and climate change.However,demand for housing is on rise in developing countries like India,where sizeable population,especially the low-income strata,still lacks decent quality structurally safe housing.Extensive use of concrete and steel in construction over more than a century has led to detrimental environmental effects such uncontrolled release of greenhouse gases/pollutants,deforestation and erosion,leading to now visible outcomes of climate change.Bamboo,on other hand provides a sustainable alternative to concrete and steel as a building material since it absorbs the atmospheric carbon dioxide,produces more oxygen than timber producing trees and is a lightweight and renewable building material.Unlike timber,it matures in four to five years and being grass family,is replenishable in nature.However,from structural point of view,the main drawback of bamboo culm is its large slenderness ratio,which renders it weak in resisting bending and compressive loads.This paper presents an alternate structural system utilizing fibre reinforced bamboo composite(FRBC)to overcome the structural deficiency of a single shoot bamboo and build a prototype structure after detailed laboratory evaluation and structural analysis.Structural elements made from FRBC are utilized for fabricating a prototype 3D frame structure,measuring about 24 m2 in plan,representing a modular unit amenable to horizontal and vertical expansion.Eco-friendly materials like cow-dung based bricks and mortar,which offer net zero additional carbon dioxide emissions and circumvent reliance on cement and river sand,have been utilized as masonry infills after structural evaluation.The built structure provides a proof-of-concept demonstration of the feasibility of using bamboo and cow-dung,sustainable building materials,for achieving a structurally safe built-environment.The technology is especially suitable for countries like India which are endowed with tropical climatic conditions.By adopting such environmentally friendly alternatives,the construction industry can create a healthier environment while addressing housing and infrastructure needs in sustainable manner.展开更多
文摘Most of the investigations regarding friction stir welding(FSW)of aluminum alloy plates have been limited to about 5 to 6mm thick plates.In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy.Two different simple-tomanufacture tool geometries were used.The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined.It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates,tool having trapezoidal pin geometry was suitable.Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min.At very low and high dwell time the ductility of welded joints are reduced significantly.
文摘Wetlands are those landscapes which are saturated with water or covered by water either perennially or for a major part of the year. Due to transforming nature of the wetlands from aquatic to terrestrial, the related physical features are not easy to be monitored. With the recent advancement in Remote sensing technique, the feature extraction of wetland with the help of different satellite derived band algebras including Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Modified NDWI (MNDWI), Normalized Difference Moisture Index (NDMI) is being used by experts. The common diagnostic features of wetlands are surface water, swamps and aquatic vegetation. The present study is based on a comparison between these four indices. Baraila wetland of Vaishali district Bihar is selected as a site for the study because the surface water of this “BAT” shaped wetland has decreased rapidly in last half decade which is alarming for the related ecology and biodiversity.
文摘An electronic circuit has been designed to mimic glycolysis, the Citric Acid (TCA) cycle and the electron transport chain. Enzymes play a vital role in metabolic pathways; similarly transistors play a vital role in electronic circuits; the characteristics of enzymes in comparison with those of transistors suggests that the properties are analagous. Enzymes possess an active site into which the substrate binds, similarly the transistor possess a layer in which the recombination of holes and electrons takes place. Hence the applied voltage in the circuit is considered as the substrate. The enthalpy values of the enzymes are converted into volts, which is to be applied to the circuit. ATP is the energy source in the metabolic pathway which functions like a potential in the electronic circuit. Some enzymes can function only with the help of a cofactor; here modelled as a switch. Using all the above electronic circuit analogues, which possess the similar characteristics of the metabolic pathway constituents, circuits have been designed.
文摘This paper analyzes and compares the performance of a new inverter topology with two types of input sources: 1) Solar PV source and 2) Ideal dc source (battery). The simulation is done in SIMULINK/MATLAB Software. It is shown that when the solar panel is connected, spikes are obtained in output voltage waveforms. These spikes are eliminated by inserting a capacitor. The capacitor is chosen for a particular power factor which is optimum with respect to cost, size and power quality. Total Harmonic Distortion, Active Power, Reactive Power, RMS Voltage and RMS Current are measured for different load power factor. Finally these results are compared with those obtained using battery with same input voltage magnitude. This Paper shows that for Solar Panel Circuit, THD, P and Q are less for 0.8 and above power factor, however below 0.8 PF, the THD, active and reactive power transfer are more. This means that the performance of Solar Panel in the proposed circuit topology is seen to be better as compared to the same circuit with battery within a range of power factor.
文摘The experimental results which were carried out by different researchers on corrosion of RCC beam were validated in ABAQUS. A finite element (FE) model similar to experimental condition was generated in ABAQUS. The model with different percentages of corrosion and with varying load conditions was also generated. The deflections of RCC beam for different corrosion percentages and for varying load conditions were then validated. The model is then used to explore the effects of bar radial expansion, due to formation of corrosion products, on the cracking of cover concrete. The predictions are compared with tests results from reinforced concrete accelerated corrosion specimens. The aim of the analytical investigation was to reveal the mechanism for the development of concrete cracking due to corrosion of reinforcement. Further the finite element model will be used to explain qualitatively the experimentally determined relationship between amount of corrosion for concrete cracking and ratio of concrete cover to bar diameter, as well as that between reinforcement bond strength and amount of corrosion.
文摘Local scour is the reduction of original bed level around any hydraulic structure.Bridge failure due to scouring has made researchers study the cause of scouring and predict the scour depth and pattern around bridge piers and foundations.Several investigators have extensively studied local scour around isolated bridge pier,but modern designs of the bridges comprise of wide span and thus group of piers rather than a single pier.The flow and scour pattern around group of piers are different from the case of a single pier due to the interaction effect.The objective of present study is to investigate the effect of mutual interference of bridge piers on local scour experimentally around two piers in non-cohesive bed.Experiments were carried out on model bridge piers of circular cross section in a meandering channel.It was observed that when front and rear piers were placed at an angular displacement ofθ=40°and 80°respectively,maximum depth of scour is maximum.Hereθis the angle the line drawn at the inlet of bend to the line joining the centre of curvature and any point on the outer portion of the bend.
文摘In today’s rapidly urbanizing world,there is dire need for adopting the principles of green/sustainable built-environment so as to mitigate the ill effects of environmental degradation and climate change.However,demand for housing is on rise in developing countries like India,where sizeable population,especially the low-income strata,still lacks decent quality structurally safe housing.Extensive use of concrete and steel in construction over more than a century has led to detrimental environmental effects such uncontrolled release of greenhouse gases/pollutants,deforestation and erosion,leading to now visible outcomes of climate change.Bamboo,on other hand provides a sustainable alternative to concrete and steel as a building material since it absorbs the atmospheric carbon dioxide,produces more oxygen than timber producing trees and is a lightweight and renewable building material.Unlike timber,it matures in four to five years and being grass family,is replenishable in nature.However,from structural point of view,the main drawback of bamboo culm is its large slenderness ratio,which renders it weak in resisting bending and compressive loads.This paper presents an alternate structural system utilizing fibre reinforced bamboo composite(FRBC)to overcome the structural deficiency of a single shoot bamboo and build a prototype structure after detailed laboratory evaluation and structural analysis.Structural elements made from FRBC are utilized for fabricating a prototype 3D frame structure,measuring about 24 m2 in plan,representing a modular unit amenable to horizontal and vertical expansion.Eco-friendly materials like cow-dung based bricks and mortar,which offer net zero additional carbon dioxide emissions and circumvent reliance on cement and river sand,have been utilized as masonry infills after structural evaluation.The built structure provides a proof-of-concept demonstration of the feasibility of using bamboo and cow-dung,sustainable building materials,for achieving a structurally safe built-environment.The technology is especially suitable for countries like India which are endowed with tropical climatic conditions.By adopting such environmentally friendly alternatives,the construction industry can create a healthier environment while addressing housing and infrastructure needs in sustainable manner.
