In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of st...In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of strip footing placed on the rock mass.By taking into account the various boundary constraints across the surface of crack edges,the study investigates the presence of two categories of surface cracks,namely(1)separated crack,and(2)fine crack.The lower bound limit analysis is employed in conjunction with the finite element method(LBFELA)to conduct the numerical analysis.In order to evaluate rock mass yielding,the power conic programming(PCP)method is utilized to implement the generalized Hoek-Brown(GHB)failure criterion.The stability of the strip footing is analyzed by determining the bearing capacity factor(Nσγ),which is presented in the form of design charts by varying the strength parameters of rock,including the Geological Strength Index(GSI),Hoek-Brown material parameter(mi),Disturbance factor(D),and Normalised Uniaxial Compressive Strength(σci/γB),whereγis the unit weight of rock mass,and B is the width of strip footing.The study also investigates the impact of cracks on strip footings,considering different positions of the crack(LC)and depths of the crack(DC).The results demonstrate that the influence of the fine crack is only noticeable until the LC/B ratio reaches 6.However,for the separated crack,its impact remains significant even when the LC/B ratio exceeds 16.The appearance of fine crack at the edge of the footing results in a decrease in the magnitude Nσγof up to 45%,indicating a substantial reduction in the stability of the footing.The failure patterns are presented and discussed in detail for various cases in this study to examine the effect of surface cracks on the strip footing and to address the extent of the plastic collapse.展开更多
Awareness on nutritive value and health benefits of rice is of vital importance in order to increase the consumption of rice in daily diet of the human beings. In this study, a total of six aromatic and two non-aromat...Awareness on nutritive value and health benefits of rice is of vital importance in order to increase the consumption of rice in daily diet of the human beings. In this study, a total of six aromatic and two non-aromatic rice accessions grown in India were analysed for their nutritional quality attributes including proximate composition, mineral contents and fatty acids. Data with three replications were used to measure Pearson＇s simple correlation co-efficient in order to establish the relationship among various nutritional quality attributes. The result on proximate composition showed that Govind Bhog had the highest moisture（13.57%） and fat（0.92%） content, which signifies its tasty attribute. Badshah Bhog exhibited the highest fibre content（0.85%）, carbohydrate content（82.70%） and food energy（365.23 k Cal per 100 g）. Among the minerals, the higher Ca（98.75 mg/kg）, Zn（17.00 mg/kg） and Fe（31.50 mg/kg） were in Gopal Bhog, whereas the highest Na（68.85 mg/kg） was in Badshah Bhog, the highest K（500.00 mg/kg） was in Swetganga, Khushboo and Sarbati. The highest contents of unsaturated fatty acids viz. oleic acid（49.14%）, linoleic acid（46.99%） and linolenic acid（1.27%） were found in Sarbati, whereas the highest content of saturated fatty acids viz. myristic acid（4.60%） and palmitic acid（31.91%） were found in Govind Bhog and stearic acid（6.47%） in Todal. The identified aromatic rice accessions Gopal Bhog, Govind Bhog and Badshah Bhog and non-aromatic rice accession Sarbati were found nutritionally superior among all eight tested accessions. The nutritional quality oriented attributes in this study were competent with recognized prominent aromatic and non-aromatic rice accessions as an index of their nutritional worth and recommend to farmers and consumers which may be graded as export quality rice with good unique nutritional values in international market.展开更多
This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criteri...This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criterion, the failure behavior of the rock mass is modeled with the help of the power cone programming in the lower bound finite element limit analysis framework. Using bearing capacity factor(Ns), the change in bearing capacity of the strip footing due to the occurrence of eccentrically inclined loading is presented. The variations of the magnitude of Ns are obtained by examining the effects of the Hoek-Brown rock mass strength parameters(uniaxial compressive strength(sci), disturbance factor(D), rock parameter(mi), and Geological Strength Index(GSI)) in the presence of different magnitudes of eccentricity(e) and inclination angle(λ) with respect to the vertical plane, and presented as design charts. Both the inclined loading modes, i.e., inclination towards the center of strip footing(+λ) and inclination away from the center of strip footing(-λ), are adopted to perform the investigation. In addition, the correlation between the input parameters and the corresponding output is developed by utilizing the artificial neural network(ANN). Additionally, from sensitivity analysis, it is observed that inclination angle(λ) is the most sensitive parameter. For practicing engineers, the obtained design equation and design charts can be beneficial to understand the bearing capacity variation in the existence of eccentrically inclined loading in mountain areas.展开更多
The role of microstructural features on in-vitro degradation and surface film development of a thermomechanically processed Mg-4Zn-0.5Ca-0.8Mn alloy has been investigated employing electrochemical studies,scanning ele...The role of microstructural features on in-vitro degradation and surface film development of a thermomechanically processed Mg-4Zn-0.5Ca-0.8Mn alloy has been investigated employing electrochemical studies,scanning electron microscopy and X-ray photoelectron spectroscopy.The specimen forged at 523 K temperature developed a coarse unimodal microstructure consisting of basal oriented grains,whereas the specimens forged at 623 K and 723 K temperatures exhibited bimodal microstructures containing randomly oriented fine grains and basal oriented coarse grains.The bimodal microstructures exerted higher resistance to corrosion compared to the unimodal microstructure in presence of a protective surface film.The optimum size distribution of fine and coarse grains as well as the prevalence of basal oriented grains led to the lowest anodic current density in the specimen forged at 623 K.The morphology of Ca_(2)Mg_(6)Zn_(3)precipitates governed the cathodic kinetics by controlling the anode to cathode surface area ratio.Despite the specimen forged at 723 K comprised comparatively lower fraction of precipitates than at 623 K,the mesh-like precipitate morphology increased the effective cathodic surface area,leading to enhanced localised corrosion in the former specimen.Optimal microstructural features developed at 623 K forging temperature formed a well-protective surface film with lower Mg(OH)_(2)to MgO ratio,exhibiting distinctly high polarization resistance and superior cytocompatibility in terms of cell-proliferation and cell-differentiation.展开更多
Pearl millet(Pennisetum glaucum)is one of the major millets with high nutritional properties.This crop exhibits exceptional resilience to drought and high temperatures.However,the processing of pearl millet poses a si...Pearl millet(Pennisetum glaucum)is one of the major millets with high nutritional properties.This crop exhibits exceptional resilience to drought and high temperatures.However,the processing of pearl millet poses a significant challenge due to its high lipid content,enzyme activity,and presence of antinutrients.Consequently,it becomes imperative to enhance the quality and prolong the shelf life of pearl millet flour by employing suitable technologies.Hydrothermal treatment in the food industry has long been seen as promising due to its potential to reduce microbial load,inactivate enzymes,and improve nutrient retention.This study aims to investigate the effects of hydrothermal treatment on the quality characteristics of pearl millet.The independent variables of the study were soaking temperature(35,45,55℃),soaking time(2,3,4 h),and steaming time(5,10,15 min).Treatment conditions had a statistically significant effect on nutrient retention.Major antinutrients like tannins and phytates were reduced by 0.99% to 5.94% and 0.36% to 6.00%,respectively,after the treatment.Lipase activity decreased significantly up to 10% with the treatment conditions.The findings of this study could potentially encourage the use of pearl millet flour in the production of various food items and promote the application of hydrothermal treatment in the field of food processing.展开更多
Metallic alloys for a given application are usually designed to achieve the desired properties by devising experimentsbased on experience, thermodynamic and kinetic principles, and various modeling and simulation exer...Metallic alloys for a given application are usually designed to achieve the desired properties by devising experimentsbased on experience, thermodynamic and kinetic principles, and various modeling and simulation exercises.However, the influence of process parameters and material properties is often non-linear and non-colligative. Inrecent years, machine learning (ML) has emerged as a promising tool to dealwith the complex interrelation betweencomposition, properties, and process parameters to facilitate accelerated discovery and development of new alloysand functionalities. In this study, we adopt an ML-based approach, coupled with genetic algorithm (GA) principles,to design novel copper alloys for achieving seemingly contradictory targets of high strength and high electricalconductivity. Initially, we establish a correlation between the alloy composition (binary to multi-component) andthe target properties, namely, electrical conductivity and mechanical strength. Catboost, an ML model coupledwith GA, was used for this task. The accuracy of the model was above 93.5%. Next, for obtaining the optimizedcompositions the outputs fromthe initial model were refined by combining the concepts of data augmentation andPareto front. Finally, the ultimate objective of predicting the target composition that would deliver the desired rangeof properties was achieved by developing an advancedMLmodel through data segregation and data augmentation.To examine the reliability of this model, results were rigorously compared and verified using several independentdata reported in the literature. This comparison substantiates that the results predicted by our model regarding thevariation of conductivity and evolution ofmicrostructure and mechanical properties with composition are in goodagreement with the reports published in the literature.展开更多
The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building fou...The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building foundation is modeled by a 200 mm by 200 mm and 40 mm thick rigid plexi-glass block. The block is placed in the middle of a 1m by 1m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by LVDT. The whole setup is mounted on a shake table and subjected to sinusoidal motions with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (> 0.65 g) of motions. The performance of a composite consisting of sand and 50% shredded rubber tire placed under the footing is found to be most promising as a low-cost effective base isolator.展开更多
Volume instability of expansive soils due to moisture fluctuations is often disastrous,causing severe damages and distortions in the supported structures.It is,therefore,necessary to adequately improve the performance...Volume instability of expansive soils due to moisture fluctuations is often disastrous,causing severe damages and distortions in the supported structures.It is,therefore,necessary to adequately improve the performance of such soils that they can favorably fulfil the post-construction stability requirements.This can be achieved through chemical stabilization using additives such as lime,cement and fly ash.In this paper,suitability of such additives under various conditions and their mechanisms are reviewed in detail.It is observed that the stabilization process primarily involves hydration,cation exchange,flocculation and pozzolanic reactions.The degree of stabilization is controlled by several factors such as additive type,additive content,soil type,soil mineralogy,curing period,curing temperature,delay in compaction,pH of soil matrix,and molding water content,including presence of nano-silica,organic matter and sulfate compounds.Provision of nano-silica not only improves soil packing but also accelerates the pozzolanic reaction.However,presence of deleterious compounds such as sulfate or organic matter can turn the treated soils unfavorable at times even worser than the unstabilized ones.展开更多
AIM:To investigate the events associated with the apoptotic effect of p-Coumaric acid,one of the phenolic components of honey,in human colorectal carcinoma(HCT-15)cells.METHODS:3-(4,5-dimethylthiazol-2-yl)-2,5-dipheny...AIM:To investigate the events associated with the apoptotic effect of p-Coumaric acid,one of the phenolic components of honey,in human colorectal carcinoma(HCT-15)cells.METHODS:3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertazolium-bromide assay was performed to determine the antiproliferative effect of p-Coumaric acid against colon cancer cells.Colony forming assay was conducted to quantify the colony inhibition in HCT15 and HT 29 colon cancer cells after p-Coumaric acid treatment.Propidium Iodide staining of the HCT15 cells using flow cytometry was done to study the changes in the cell cycle of treated cells.Identification of apoptosis was done using scanning electron microscope and photomicrograph evaluation of HCT 15cells after exposing to p-Coumaric acid.Levels of reactive oxygen species(ROS)of HCT 15 cells exposed to p-Coumaric acid was evaluated using 2’,7’-dichlorfluorescein-diacetate.Mitochondrial membrane potential of HCT-15 was assessed using rhodamine-123 with the help of flow cytometry.Lipid layer breaks associated with p-Coumaric acid treatment was quantified using the dye merocyanine 540.Apoptosis was confirmed and quantified using flow cytometric analysis of HCT15 cells subjected to p-Coumaric acid treatment after staining with YO-PRO-1.RESULTS:Antiproliferative test showed p-Coumaric acid has an inhibitory effect on HCT 15 and HT 29 cells with an IC50(concentration for 50%inhibition)value of 1400 and 1600μmol/L respectively.Colony forming assay revealed the time-dependent inhibition of HCT 15 and HT 29 cells subjected to p-Coumaric acid treatment.Propidium iodide staining of treated HCT 15cells showed increasing accumulation of apoptotic cells(37.45±1.98 vs 1.07±1.01)at sub-G1phase of the cell cycle after p-Coumaric acid treatment.HCT-15 cells observed with photomicrograph and scanning electron microscope showed the signs of apoptosis like blebbing and shrinkage after p-Coumaric acid exposure.Evaluation of the lipid layer showed increasing lipid layer breaks was associated with the growth inhibition of p-Coumaric acid.A fall in mitochondrial membrane potential and increasing ROS generation was observed in the p-Coumaric acid treated cells.Further apoptosis evaluated by YO-PRO-1 staining also showed the timedependent increase of apoptotic cells after treatment.CONCLUSION:These results depicted that p-Coumaric acid inhibited the growth of colon cancer cells by inducing apoptosis through ROS-mitochondrial pathway.展开更多
This research aims to study the significance of Gd addition(0wt%–2wt%) on the microstructure and mechanical properties of Mg–9Al alloy. The effect of Gd addition on the microstructure was investigated via X-ray diff...This research aims to study the significance of Gd addition(0wt%–2wt%) on the microstructure and mechanical properties of Mg–9Al alloy. The effect of Gd addition on the microstructure was investigated via X-ray diffraction(XRD), optical microscopy, scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The Mg–9Al alloy contained two phases, α-Mg and β-Mg_(17)Al_(12). Alloying with Gd led to the emergence of a new rectangular-shaped phase, Al_2Gd. The grain size also decreased marginally upon Gd addition. The ultimate tensile strength and microhardness of Mg–9Al alloy increased by 23% and 19%, respectively, upon 1.5wt% Gd addition. We observed that, although Mg–9Al–2.0Gd alloy exhibited the smallest grain size(181 μm) and the highest dislocation density(5.1 × 10^(10) m^(-2)) among the investigated compositions, the Mg–9Al–1.5Gd alloy displayed the best mechanical properties. This anomalous behavior was observed because the Al_2Gd phase was uniformly distributed and present in abundance in Mg–9Al–1.5Gd alloy, whereas it was coarsened and asymmetrically conglomerated in Mg–9Al–2.0Gd.展开更多
The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nep...The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis(LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km2, that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and6800 m above mean sea level(a msl). With a total surface area of 37.9 km2, these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.展开更多
In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydra...In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical kinetics.The estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.展开更多
The present study investigates the mechanical and in-vitro corrosion behavior of Mg-4Zn-0.5Ca-0.8Mn alloy in optimum homogenized conditions.The optimization of the homogenization parameters has been carried out employ...The present study investigates the mechanical and in-vitro corrosion behavior of Mg-4Zn-0.5Ca-0.8Mn alloy in optimum homogenized conditions.The optimization of the homogenization parameters has been carried out employing thermodynamic calculations and kinetic modeling.The model utilizes the inter-diffusivity of the solute elements and predicts that∼6–24 h of homogenization at 633 K effectively redistributes the elements in the Mg matrix.Based on the insights obtained from the simulations,the as-cast Mg-4Zn-0.5Ca-0.8Mn alloy was subjected to homogenization heat treatment process for 6–24h.The microstructural study through optical microscopy and scanning electron microscopy(SEM)revealed that the interconnected network of second phase precipitates substantially dissolve within 24 h,implying adequate homogenization.Moreover,fine Mg-Zn based precipitates with varied morphology and phase fractions also evolved during homogenization treatment,as confirmed through SEM and transmission electron microscopy.In the 12 h homogenized specimen,the highest fraction of uniformly dispersed fine precipitates resulted in the highest strength(∼225 MPa).On the other hand,a substantial disruption in coarse precipitate network and lower aspect ratio of fine Mg-Zn precipitates led to the highest ductility(∼8%)in this specimen.In the 24 h homogenized specimen,the ductility reduced marginally owing to higher aspect ratio of fine precipitates.The immersion and electrochemical tests(viz.,potentiodynamic polarization and electrochemical impedance spectroscopy)carried out in Hank’s solution revealed that the 24 h homogenized specimen exhibits the best corrosion properties.The least fraction of Ca_(2)Mg_(6)Zn_(3)phase with maximum disruption in interconnectivity,in combination with a small fraction of fine equilibrium MgZn_(2)precipitates,resulted in suppression of localized corrosion in this specimen.This promotes the formation of the most stable and compact product layer over the specimen,resulting in the highest corrosion resistance.展开更多
The behavior of braced excavation in dry sand under a seismic condition is investigated in this paper.A series of shake table tests on a reduced scale model of a retaining wall with one level of bracing were conducted...The behavior of braced excavation in dry sand under a seismic condition is investigated in this paper.A series of shake table tests on a reduced scale model of a retaining wall with one level of bracing were conducted to study the effect of different design parameters such as excavation depth,acceleration amplitude and wall stiffness.Numerical analyses using FLAC 2D were also performed considering one level of bracing.The strut forces,lateral displacements and bending moments in the wall at the end of earthquake motion were compared with experimental results.The study showed that in a post-seismic condition,when other factors were constant,lateral displacement,bending moment,strut forces and maximum ground surface displacement increased with excavation depth and the amplitude of base acceleration.The study also showed that as wall stiffness decreased,the lateral displacement of the wall and ground surface displacement increased,but the bending moment of the wall and strut forces decreased.The net earth pressure behind the walls was influenced by excavation depth and the peak acceleration amplitude,but did not change significantly with wall stiffness.Strut force was the least affected parameter when compared with others under a seismic condition.展开更多
Minerals are now being extracted from deep mines due to drying up of resource in shallow ground. The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with fill...Minerals are now being extracted from deep mines due to drying up of resource in shallow ground. The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filling technology. In addition, high horizontal stress may cause collapse of hanging wall and footwall rocks, hence designing of suitable crown pillars is absolutely necessary for imposing overall safety of the stopes. This paper provides a methodology for the evaluation of the required thickness of crown pillars for safe operation at depth ranging from 600 m to 1000 m. Analyses are conducted with the results of 108 non-linear numerical models considering Drucker-Prager material model in plane strain condition. Material properties of ore body rock and thickness of crown pillars are varied and safety factors of pillars estimated. Then, a generalized statistical relationship between the safety factors of crown pillars with the various input parameters is developed. The developed multivariate regression model is utilized for generating design/stability charts of pillars for different geo-mining conditions.These design charts can be used for the design of crown pillar thickness with the depth of the working,taking into account the changes of the rock mass conditions in underground metal mine.展开更多
Fluid mechanical peristaltic transport through esophagus is studied in the paper. A mathematical model has been developed to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube le...Fluid mechanical peristaltic transport through esophagus is studied in the paper. A mathematical model has been developed to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of a viscous fluid is considered here to depict the non-Newtonian behaviour of the fluid. The model is formulated and analyzed specifically to explore some important information concerning the movement of food bolus through esophagus. The analysis is carried out by using the lubrication theory. The study is particularly suitable for the cases where the Reynolds number is small. The esophagus is treated as a circular tube through which the transport of food bolus takes place by periodic contraction of the esophageal wall. Variation of different variables concerned with the transport phenomena such as pressure, flow velocities, particle trajectory, and reflux is investigated for a single wave as well as a train of periodic peristaltic waves. The locally variable pressure is seen to be highly sensitive to the flow index ＂n＂. The study clearly shows that continuous fluid transport for Newtonian/rheological fluids by wave train propagation is more effective than widely spaced single wave propagation in the case of peristaltic movement of food bolus in the esophagus.展开更多
The mineralogy and trace element contents in coals from the West Bokaro coalfield, which is the one of the biggest Gondwana coalfields of India, were studied to delineate enrichment of trace elements and their modes o...The mineralogy and trace element contents in coals from the West Bokaro coalfield, which is the one of the biggest Gondwana coalfields of India, were studied to delineate enrichment of trace elements and their modes of occur- rence. Elemental concentrations with reference to their crustal abundances indicated that coals are relatively enriched in As （4.4-15.5 mg/kg）, Cd （0.3-3.0 mg/kg）, Cu （28.0-68.1 mg/kg） and V （46.6-178.0 mg/kg）; depleted in Co （10.8-28.4 mg/ kg）, Mn （7.6-483.4 mg/kg）, Ni （13.0-31.6 mg/kg）, Cr （14.2-85.5 mg/kg） and Zn （5.25-70.4 mg/kg）. The concentration of As, Cd, Co, Cu and V were higher than the average values of world and Indian coals. Mineralogical study carried out by X-ray diffraction shows that quartz and kaolinite occur as dominant mineral phases in this coal. Fourier transform infrared spectroscopy pattern suggests organic structures primarily containing aromatic nuclei, aliphatic side chain and some oxygen containing groups. The modes of occurrence of trace elements present in these coals have been determined through statistical approach. Both Cu and Cr are more closely associated with mineral matter, whereas Co is dominantly present with its organic form. The concentrations of Cd, Mn, Ni, Zn, As and V have apparently occur in both organic and inorganic constituents. This study would be helpful to assess the potential environmental impacts during mining and combustion of this coal.展开更多
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
The elemental micro-segregation characteristic within the weld zone for ytterbium fiber laser welded Hastelloy C-276sheet was investigated. The analysis of segregation ratio and equilibrium distribution coefficient of...The elemental micro-segregation characteristic within the weld zone for ytterbium fiber laser welded Hastelloy C-276sheet was investigated. The analysis of segregation ratio and equilibrium distribution coefficient of elements, determined throughEDS data, indicate the reduction in micro-segregation of elements compared with the previous reported literatures for laser weldedHastelloy C-276. High melting efficiency of ytterbium fiber laser, reduction in the amount of linear heat input, and high cooling rateof the mushy zone lead to the reduction in micro-segregation. The melting efficiency of ytterbium fiber laser for welding of HastelloyC-276 of 64% is higher than that （48%） of conventional welding methods. High melting efficiency leads to the reduction in the linearheat input required for welding. Hence, in the present investigation, the same was found to substantially reduce as compared to theprevious reported literature. The cooling rate from liquidus temperature to solidus temperature at the weld centerline was found to bein the order of 10^3℃/s. Cellular dendritic substructure that constituted for lower micro-segregation was formed at the weldcenterline.展开更多
COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) wit...COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) with limited relaxation in non-hotspot areas. This strict lockdown has severely curtailed human activity across India. Here, aerosol concentrations of particular matters(PM) i.e., PM,PM, carbon monoxide(CO), nitrogen dioxide(NO), sulphur dioxide(SO), ammonia(NH) and ozone(O), and associated temperature fluctuation in four megacities(Delhi, Mumbai, Kolkata, and Chennai)from different regions of India were investigated. In this pandemic period, air temperature of Delhi,Kolkata, Mumbai and Chennai has decreased about 3 ℃, 2.5 ℃, 2 ℃ and 2 ℃ respectively. Compared to previous years and pre-lockdown period, air pollutants level and aerosol concentration(-41.91%,-37.13%,-54.94% and-46.79% respectively for Delhi, Mumbai, Kolkata and Chennai) in these four megacities has improved drastically during this lockdown period. Emission of PMhas experienced the highest decrease in these megacities, which directly shows the positive impact of restricted vehicular movement. Restricted emissions produce encouraging results in terms of urban air quality and temperature, which may encourage policymakers to consider it in terms of environmental sustainability.展开更多
基金supported by the Centre for Development of Advanced Computing (CDAC), Pune
文摘In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of strip footing placed on the rock mass.By taking into account the various boundary constraints across the surface of crack edges,the study investigates the presence of two categories of surface cracks,namely(1)separated crack,and(2)fine crack.The lower bound limit analysis is employed in conjunction with the finite element method(LBFELA)to conduct the numerical analysis.In order to evaluate rock mass yielding,the power conic programming(PCP)method is utilized to implement the generalized Hoek-Brown(GHB)failure criterion.The stability of the strip footing is analyzed by determining the bearing capacity factor(Nσγ),which is presented in the form of design charts by varying the strength parameters of rock,including the Geological Strength Index(GSI),Hoek-Brown material parameter(mi),Disturbance factor(D),and Normalised Uniaxial Compressive Strength(σci/γB),whereγis the unit weight of rock mass,and B is the width of strip footing.The study also investigates the impact of cracks on strip footings,considering different positions of the crack(LC)and depths of the crack(DC).The results demonstrate that the influence of the fine crack is only noticeable until the LC/B ratio reaches 6.However,for the separated crack,its impact remains significant even when the LC/B ratio exceeds 16.The appearance of fine crack at the edge of the footing results in a decrease in the magnitude Nσγof up to 45%,indicating a substantial reduction in the stability of the footing.The failure patterns are presented and discussed in detail for various cases in this study to examine the effect of surface cracks on the strip footing and to address the extent of the plastic collapse.
基金financially supported by Department of Science and Technology,Ministry of Science and Technology,Government of India for an individual research fellowship(Grant No.IF120725 2012/686)
文摘Awareness on nutritive value and health benefits of rice is of vital importance in order to increase the consumption of rice in daily diet of the human beings. In this study, a total of six aromatic and two non-aromatic rice accessions grown in India were analysed for their nutritional quality attributes including proximate composition, mineral contents and fatty acids. Data with three replications were used to measure Pearson＇s simple correlation co-efficient in order to establish the relationship among various nutritional quality attributes. The result on proximate composition showed that Govind Bhog had the highest moisture（13.57%） and fat（0.92%） content, which signifies its tasty attribute. Badshah Bhog exhibited the highest fibre content（0.85%）, carbohydrate content（82.70%） and food energy（365.23 k Cal per 100 g）. Among the minerals, the higher Ca（98.75 mg/kg）, Zn（17.00 mg/kg） and Fe（31.50 mg/kg） were in Gopal Bhog, whereas the highest Na（68.85 mg/kg） was in Badshah Bhog, the highest K（500.00 mg/kg） was in Swetganga, Khushboo and Sarbati. The highest contents of unsaturated fatty acids viz. oleic acid（49.14%）, linoleic acid（46.99%） and linolenic acid（1.27%） were found in Sarbati, whereas the highest content of saturated fatty acids viz. myristic acid（4.60%） and palmitic acid（31.91%） were found in Govind Bhog and stearic acid（6.47%） in Todal. The identified aromatic rice accessions Gopal Bhog, Govind Bhog and Badshah Bhog and non-aromatic rice accession Sarbati were found nutritionally superior among all eight tested accessions. The nutritional quality oriented attributes in this study were competent with recognized prominent aromatic and non-aromatic rice accessions as an index of their nutritional worth and recommend to farmers and consumers which may be graded as export quality rice with good unique nutritional values in international market.
基金supported by Centre for Development of Advanced Computing (CDAC), Pune。
文摘This paper deals with the bearing capacity determination of strip footing on a rock mass in hilly area by considering the influence of inclined and eccentric loading. Applying the generalized HoekBrown failure criterion, the failure behavior of the rock mass is modeled with the help of the power cone programming in the lower bound finite element limit analysis framework. Using bearing capacity factor(Ns), the change in bearing capacity of the strip footing due to the occurrence of eccentrically inclined loading is presented. The variations of the magnitude of Ns are obtained by examining the effects of the Hoek-Brown rock mass strength parameters(uniaxial compressive strength(sci), disturbance factor(D), rock parameter(mi), and Geological Strength Index(GSI)) in the presence of different magnitudes of eccentricity(e) and inclination angle(λ) with respect to the vertical plane, and presented as design charts. Both the inclined loading modes, i.e., inclination towards the center of strip footing(+λ) and inclination away from the center of strip footing(-λ), are adopted to perform the investigation. In addition, the correlation between the input parameters and the corresponding output is developed by utilizing the artificial neural network(ANN). Additionally, from sensitivity analysis, it is observed that inclination angle(λ) is the most sensitive parameter. For practicing engineers, the obtained design equation and design charts can be beneficial to understand the bearing capacity variation in the existence of eccentrically inclined loading in mountain areas.
文摘The role of microstructural features on in-vitro degradation and surface film development of a thermomechanically processed Mg-4Zn-0.5Ca-0.8Mn alloy has been investigated employing electrochemical studies,scanning electron microscopy and X-ray photoelectron spectroscopy.The specimen forged at 523 K temperature developed a coarse unimodal microstructure consisting of basal oriented grains,whereas the specimens forged at 623 K and 723 K temperatures exhibited bimodal microstructures containing randomly oriented fine grains and basal oriented coarse grains.The bimodal microstructures exerted higher resistance to corrosion compared to the unimodal microstructure in presence of a protective surface film.The optimum size distribution of fine and coarse grains as well as the prevalence of basal oriented grains led to the lowest anodic current density in the specimen forged at 623 K.The morphology of Ca_(2)Mg_(6)Zn_(3)precipitates governed the cathodic kinetics by controlling the anode to cathode surface area ratio.Despite the specimen forged at 723 K comprised comparatively lower fraction of precipitates than at 623 K,the mesh-like precipitate morphology increased the effective cathodic surface area,leading to enhanced localised corrosion in the former specimen.Optimal microstructural features developed at 623 K forging temperature formed a well-protective surface film with lower Mg(OH)_(2)to MgO ratio,exhibiting distinctly high polarization resistance and superior cytocompatibility in terms of cell-proliferation and cell-differentiation.
基金the Ministry of Human Resource Development,Govt.of India,for providing scholarship grants to the authors.
文摘Pearl millet(Pennisetum glaucum)is one of the major millets with high nutritional properties.This crop exhibits exceptional resilience to drought and high temperatures.However,the processing of pearl millet poses a significant challenge due to its high lipid content,enzyme activity,and presence of antinutrients.Consequently,it becomes imperative to enhance the quality and prolong the shelf life of pearl millet flour by employing suitable technologies.Hydrothermal treatment in the food industry has long been seen as promising due to its potential to reduce microbial load,inactivate enzymes,and improve nutrient retention.This study aims to investigate the effects of hydrothermal treatment on the quality characteristics of pearl millet.The independent variables of the study were soaking temperature(35,45,55℃),soaking time(2,3,4 h),and steaming time(5,10,15 min).Treatment conditions had a statistically significant effect on nutrient retention.Major antinutrients like tannins and phytates were reduced by 0.99% to 5.94% and 0.36% to 6.00%,respectively,after the treatment.Lipase activity decreased significantly up to 10% with the treatment conditions.The findings of this study could potentially encourage the use of pearl millet flour in the production of various food items and promote the application of hydrothermal treatment in the field of food processing.
文摘Metallic alloys for a given application are usually designed to achieve the desired properties by devising experimentsbased on experience, thermodynamic and kinetic principles, and various modeling and simulation exercises.However, the influence of process parameters and material properties is often non-linear and non-colligative. Inrecent years, machine learning (ML) has emerged as a promising tool to dealwith the complex interrelation betweencomposition, properties, and process parameters to facilitate accelerated discovery and development of new alloysand functionalities. In this study, we adopt an ML-based approach, coupled with genetic algorithm (GA) principles,to design novel copper alloys for achieving seemingly contradictory targets of high strength and high electricalconductivity. Initially, we establish a correlation between the alloy composition (binary to multi-component) andthe target properties, namely, electrical conductivity and mechanical strength. Catboost, an ML model coupledwith GA, was used for this task. The accuracy of the model was above 93.5%. Next, for obtaining the optimizedcompositions the outputs fromthe initial model were refined by combining the concepts of data augmentation andPareto front. Finally, the ultimate objective of predicting the target composition that would deliver the desired rangeof properties was achieved by developing an advancedMLmodel through data segregation and data augmentation.To examine the reliability of this model, results were rigorously compared and verified using several independentdata reported in the literature. This comparison substantiates that the results predicted by our model regarding thevariation of conductivity and evolution ofmicrostructure and mechanical properties with composition are in goodagreement with the reports published in the literature.
基金funding by Bhabha Atomic Research Centre (BARC),Mumbai
文摘The performance of a well-designed layer of sand, and composites like layer of sand mixed with shredded rubber tire (RSM) as low cost base isolators, is studied in shake table tests in the laboratory. The building foundation is modeled by a 200 mm by 200 mm and 40 mm thick rigid plexi-glass block. The block is placed in the middle of a 1m by 1m tank filled with sand. The selected base isolator is placed between the block and the sand foundation. Accelerometers are placed on top of the footing and foundation sand layer. The displacement of the footing is also measured by LVDT. The whole setup is mounted on a shake table and subjected to sinusoidal motions with varying amplitude and frequency. Sand is found to be effective only at very high amplitude (> 0.65 g) of motions. The performance of a composite consisting of sand and 50% shredded rubber tire placed under the footing is found to be most promising as a low-cost effective base isolator.
文摘Volume instability of expansive soils due to moisture fluctuations is often disastrous,causing severe damages and distortions in the supported structures.It is,therefore,necessary to adequately improve the performance of such soils that they can favorably fulfil the post-construction stability requirements.This can be achieved through chemical stabilization using additives such as lime,cement and fly ash.In this paper,suitability of such additives under various conditions and their mechanisms are reviewed in detail.It is observed that the stabilization process primarily involves hydration,cation exchange,flocculation and pozzolanic reactions.The degree of stabilization is controlled by several factors such as additive type,additive content,soil type,soil mineralogy,curing period,curing temperature,delay in compaction,pH of soil matrix,and molding water content,including presence of nano-silica,organic matter and sulfate compounds.Provision of nano-silica not only improves soil packing but also accelerates the pozzolanic reaction.However,presence of deleterious compounds such as sulfate or organic matter can turn the treated soils unfavorable at times even worser than the unstabilized ones.
基金Supported by Universiti Teknologi Malaysia,Malaysia for providing Visiting Research Fellowship
文摘AIM:To investigate the events associated with the apoptotic effect of p-Coumaric acid,one of the phenolic components of honey,in human colorectal carcinoma(HCT-15)cells.METHODS:3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertazolium-bromide assay was performed to determine the antiproliferative effect of p-Coumaric acid against colon cancer cells.Colony forming assay was conducted to quantify the colony inhibition in HCT15 and HT 29 colon cancer cells after p-Coumaric acid treatment.Propidium Iodide staining of the HCT15 cells using flow cytometry was done to study the changes in the cell cycle of treated cells.Identification of apoptosis was done using scanning electron microscope and photomicrograph evaluation of HCT 15cells after exposing to p-Coumaric acid.Levels of reactive oxygen species(ROS)of HCT 15 cells exposed to p-Coumaric acid was evaluated using 2’,7’-dichlorfluorescein-diacetate.Mitochondrial membrane potential of HCT-15 was assessed using rhodamine-123 with the help of flow cytometry.Lipid layer breaks associated with p-Coumaric acid treatment was quantified using the dye merocyanine 540.Apoptosis was confirmed and quantified using flow cytometric analysis of HCT15 cells subjected to p-Coumaric acid treatment after staining with YO-PRO-1.RESULTS:Antiproliferative test showed p-Coumaric acid has an inhibitory effect on HCT 15 and HT 29 cells with an IC50(concentration for 50%inhibition)value of 1400 and 1600μmol/L respectively.Colony forming assay revealed the time-dependent inhibition of HCT 15 and HT 29 cells subjected to p-Coumaric acid treatment.Propidium iodide staining of treated HCT 15cells showed increasing accumulation of apoptotic cells(37.45±1.98 vs 1.07±1.01)at sub-G1phase of the cell cycle after p-Coumaric acid treatment.HCT-15 cells observed with photomicrograph and scanning electron microscope showed the signs of apoptosis like blebbing and shrinkage after p-Coumaric acid exposure.Evaluation of the lipid layer showed increasing lipid layer breaks was associated with the growth inhibition of p-Coumaric acid.A fall in mitochondrial membrane potential and increasing ROS generation was observed in the p-Coumaric acid treated cells.Further apoptosis evaluated by YO-PRO-1 staining also showed the timedependent increase of apoptotic cells after treatment.CONCLUSION:These results depicted that p-Coumaric acid inhibited the growth of colon cancer cells by inducing apoptosis through ROS-mitochondrial pathway.
基金the financial support of the Council of Scientific and Industrial ResearchMinistry of Human Resource DevelopmentGovernment of India
文摘This research aims to study the significance of Gd addition(0wt%–2wt%) on the microstructure and mechanical properties of Mg–9Al alloy. The effect of Gd addition on the microstructure was investigated via X-ray diffraction(XRD), optical microscopy, scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The Mg–9Al alloy contained two phases, α-Mg and β-Mg_(17)Al_(12). Alloying with Gd led to the emergence of a new rectangular-shaped phase, Al_2Gd. The grain size also decreased marginally upon Gd addition. The ultimate tensile strength and microhardness of Mg–9Al alloy increased by 23% and 19%, respectively, upon 1.5wt% Gd addition. We observed that, although Mg–9Al–2.0Gd alloy exhibited the smallest grain size(181 μm) and the highest dislocation density(5.1 × 10^(10) m^(-2)) among the investigated compositions, the Mg–9Al–1.5Gd alloy displayed the best mechanical properties. This anomalous behavior was observed because the Al_2Gd phase was uniformly distributed and present in abundance in Mg–9Al–1.5Gd alloy, whereas it was coarsened and asymmetrically conglomerated in Mg–9Al–2.0Gd.
文摘The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis(LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km2, that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and6800 m above mean sea level(a msl). With a total surface area of 37.9 km2, these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.
基金Ministry of Steel-India,New Delhi for sponsoring the program to carry out the research work
文摘In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical kinetics.The estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.
文摘The present study investigates the mechanical and in-vitro corrosion behavior of Mg-4Zn-0.5Ca-0.8Mn alloy in optimum homogenized conditions.The optimization of the homogenization parameters has been carried out employing thermodynamic calculations and kinetic modeling.The model utilizes the inter-diffusivity of the solute elements and predicts that∼6–24 h of homogenization at 633 K effectively redistributes the elements in the Mg matrix.Based on the insights obtained from the simulations,the as-cast Mg-4Zn-0.5Ca-0.8Mn alloy was subjected to homogenization heat treatment process for 6–24h.The microstructural study through optical microscopy and scanning electron microscopy(SEM)revealed that the interconnected network of second phase precipitates substantially dissolve within 24 h,implying adequate homogenization.Moreover,fine Mg-Zn based precipitates with varied morphology and phase fractions also evolved during homogenization treatment,as confirmed through SEM and transmission electron microscopy.In the 12 h homogenized specimen,the highest fraction of uniformly dispersed fine precipitates resulted in the highest strength(∼225 MPa).On the other hand,a substantial disruption in coarse precipitate network and lower aspect ratio of fine Mg-Zn precipitates led to the highest ductility(∼8%)in this specimen.In the 24 h homogenized specimen,the ductility reduced marginally owing to higher aspect ratio of fine precipitates.The immersion and electrochemical tests(viz.,potentiodynamic polarization and electrochemical impedance spectroscopy)carried out in Hank’s solution revealed that the 24 h homogenized specimen exhibits the best corrosion properties.The least fraction of Ca_(2)Mg_(6)Zn_(3)phase with maximum disruption in interconnectivity,in combination with a small fraction of fine equilibrium MgZn_(2)precipitates,resulted in suppression of localized corrosion in this specimen.This promotes the formation of the most stable and compact product layer over the specimen,resulting in the highest corrosion resistance.
文摘The behavior of braced excavation in dry sand under a seismic condition is investigated in this paper.A series of shake table tests on a reduced scale model of a retaining wall with one level of bracing were conducted to study the effect of different design parameters such as excavation depth,acceleration amplitude and wall stiffness.Numerical analyses using FLAC 2D were also performed considering one level of bracing.The strut forces,lateral displacements and bending moments in the wall at the end of earthquake motion were compared with experimental results.The study showed that in a post-seismic condition,when other factors were constant,lateral displacement,bending moment,strut forces and maximum ground surface displacement increased with excavation depth and the amplitude of base acceleration.The study also showed that as wall stiffness decreased,the lateral displacement of the wall and ground surface displacement increased,but the bending moment of the wall and strut forces decreased.The net earth pressure behind the walls was influenced by excavation depth and the peak acceleration amplitude,but did not change significantly with wall stiffness.Strut force was the least affected parameter when compared with others under a seismic condition.
文摘Minerals are now being extracted from deep mines due to drying up of resource in shallow ground. The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filling technology. In addition, high horizontal stress may cause collapse of hanging wall and footwall rocks, hence designing of suitable crown pillars is absolutely necessary for imposing overall safety of the stopes. This paper provides a methodology for the evaluation of the required thickness of crown pillars for safe operation at depth ranging from 600 m to 1000 m. Analyses are conducted with the results of 108 non-linear numerical models considering Drucker-Prager material model in plane strain condition. Material properties of ore body rock and thickness of crown pillars are varied and safety factors of pillars estimated. Then, a generalized statistical relationship between the safety factors of crown pillars with the various input parameters is developed. The developed multivariate regression model is utilized for generating design/stability charts of pillars for different geo-mining conditions.These design charts can be used for the design of crown pillar thickness with the depth of the working,taking into account the changes of the rock mass conditions in underground metal mine.
基金the Council of Scientific and Industrial Research (CSIR) of New Delhi for awarding him a scientific research fund
文摘Fluid mechanical peristaltic transport through esophagus is studied in the paper. A mathematical model has been developed to study the peristaltic transport of a rheological fluid for arbitrary wave shapes and tube lengths. The Ostwald-de Waele power law of a viscous fluid is considered here to depict the non-Newtonian behaviour of the fluid. The model is formulated and analyzed specifically to explore some important information concerning the movement of food bolus through esophagus. The analysis is carried out by using the lubrication theory. The study is particularly suitable for the cases where the Reynolds number is small. The esophagus is treated as a circular tube through which the transport of food bolus takes place by periodic contraction of the esophageal wall. Variation of different variables concerned with the transport phenomena such as pressure, flow velocities, particle trajectory, and reflux is investigated for a single wave as well as a train of periodic peristaltic waves. The locally variable pressure is seen to be highly sensitive to the flow index ＂n＂. The study clearly shows that continuous fluid transport for Newtonian/rheological fluids by wave train propagation is more effective than widely spaced single wave propagation in the case of peristaltic movement of food bolus in the esophagus.
文摘The mineralogy and trace element contents in coals from the West Bokaro coalfield, which is the one of the biggest Gondwana coalfields of India, were studied to delineate enrichment of trace elements and their modes of occur- rence. Elemental concentrations with reference to their crustal abundances indicated that coals are relatively enriched in As （4.4-15.5 mg/kg）, Cd （0.3-3.0 mg/kg）, Cu （28.0-68.1 mg/kg） and V （46.6-178.0 mg/kg）; depleted in Co （10.8-28.4 mg/ kg）, Mn （7.6-483.4 mg/kg）, Ni （13.0-31.6 mg/kg）, Cr （14.2-85.5 mg/kg） and Zn （5.25-70.4 mg/kg）. The concentration of As, Cd, Co, Cu and V were higher than the average values of world and Indian coals. Mineralogical study carried out by X-ray diffraction shows that quartz and kaolinite occur as dominant mineral phases in this coal. Fourier transform infrared spectroscopy pattern suggests organic structures primarily containing aromatic nuclei, aliphatic side chain and some oxygen containing groups. The modes of occurrence of trace elements present in these coals have been determined through statistical approach. Both Cu and Cr are more closely associated with mineral matter, whereas Co is dominantly present with its organic form. The concentrations of Cd, Mn, Ni, Zn, As and V have apparently occur in both organic and inorganic constituents. This study would be helpful to assess the potential environmental impacts during mining and combustion of this coal.
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The elemental micro-segregation characteristic within the weld zone for ytterbium fiber laser welded Hastelloy C-276sheet was investigated. The analysis of segregation ratio and equilibrium distribution coefficient of elements, determined throughEDS data, indicate the reduction in micro-segregation of elements compared with the previous reported literatures for laser weldedHastelloy C-276. High melting efficiency of ytterbium fiber laser, reduction in the amount of linear heat input, and high cooling rateof the mushy zone lead to the reduction in micro-segregation. The melting efficiency of ytterbium fiber laser for welding of HastelloyC-276 of 64% is higher than that （48%） of conventional welding methods. High melting efficiency leads to the reduction in the linearheat input required for welding. Hence, in the present investigation, the same was found to substantially reduce as compared to theprevious reported literature. The cooling rate from liquidus temperature to solidus temperature at the weld centerline was found to bein the order of 10^3℃/s. Cellular dendritic substructure that constituted for lower micro-segregation was formed at the weldcenterline.
文摘COVID-19 pandemic has forced to lockdown entire India starting from 24th March 2020 to 14th April 2020(first phase), extended up to 3rd May 2020(second phase), and further extended up to 17th May 2020(third phase) with limited relaxation in non-hotspot areas. This strict lockdown has severely curtailed human activity across India. Here, aerosol concentrations of particular matters(PM) i.e., PM,PM, carbon monoxide(CO), nitrogen dioxide(NO), sulphur dioxide(SO), ammonia(NH) and ozone(O), and associated temperature fluctuation in four megacities(Delhi, Mumbai, Kolkata, and Chennai)from different regions of India were investigated. In this pandemic period, air temperature of Delhi,Kolkata, Mumbai and Chennai has decreased about 3 ℃, 2.5 ℃, 2 ℃ and 2 ℃ respectively. Compared to previous years and pre-lockdown period, air pollutants level and aerosol concentration(-41.91%,-37.13%,-54.94% and-46.79% respectively for Delhi, Mumbai, Kolkata and Chennai) in these four megacities has improved drastically during this lockdown period. Emission of PMhas experienced the highest decrease in these megacities, which directly shows the positive impact of restricted vehicular movement. Restricted emissions produce encouraging results in terms of urban air quality and temperature, which may encourage policymakers to consider it in terms of environmental sustainability.
