Numerical Study on Failure of Thin Composite Conoidal Shell Roofs Considering Geometric Nonlinearity

Kaustav Bakshi,Dipankar Chakravorty 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.3

Thin laminated composite conoidal shell roofs are popular among civil engineers due to its stiff, singly ruled and aesthetically appealing geometry. Such surfaces may undergo large displacements under transverse static overloading. Since no researchers reported failure of laminated conoids using nonlinear strains the authors aim to fill the void in the literature. A finite element code is proposed considering von-Karman nonlinearity. The study of linear and nonlinear failure loads clearly indicates that the linear formulation wrongly overestimates the failure loads and hence, not acceptable from practical engineering standpoint. Moreover, displacements at failure, the coordinate locations from where the failure initiates and the lamina stress initiating failure in the shell are also studied.

Relative static and dynamic performances of composite conoidal shell roofs

Kaustav Bakshi,Dipankar Chakravorty 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.15 No.4

Conoidal shells are doubly curved stiff surfaces which are easy to cast and fabricate due to their singly ruled property. Application of laminated composites in fabrication of conoidal shells reduces gravity forces and mass induced forces compared to the isotropic constructions due to the high strength to weight ratio of the material. These light weight shells are preferred in the industry to cover large column free open spaces. To ensure design reliability under service conditions, detailed knowledge about different behavioral aspects of conoidal shell is necessary. Hence, in this paper, static bending, free and forced vibration responses of composite conoidal shells are studied. Lagrange's equation of motion is used in conjunction with Hamilton's principle to derive governing equations of the shell. A finite element code using eight noded curved quadratic isoparametric elements is developed to get the solutions. Uniformly distributed load for static bending analysis and three different load time histories for solution of forced vibration problems are considered. Eight different stacking sequences of graphite-epoxy composite and two different boundary conditions are taken up in the present study. The study shows that relative performances of different shell combinations in terms of static behaviour cannot provide an idea about how they will relatively behave under dynamic loads and also the fact that the points of occurrence of maximum static and dynamic displacement may not be same on a shell surface.

Moisture distribution in concrete subjected to rain induced wetting-drying

Kaustav Sarkar,Bishwajit Bhattacharjee 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.6

A rational estimation of moisture distribution in structural concrete is vital for predicting the possible extent and rate of progression of impending degradation processes. The paper proposes a numerical scheme for analysing the evolution of moisture distribution in concrete subjected to wetting-drying exposure caused by intermittent periods of rainfall. The proposed paradigm is based on the stage wise implementation of non-linear finite element (FE) analysis, with each stage representing a distinct phase of a typical wet-dry cycle. The associated boundary conditions have been constituted to realize the influence of various meteorological elements such as rain, wind, relative humidity and temperature on the exposed concrete surface. The reliability of the developed scheme has been demonstrated through its application for the simulation of experimentally recorded moisture profiles reported in published literature. A sensitivity analysis has also been carried out to study the influence of critical material properties on simulated results. The proposed scheme is vital to the service life modelling of concrete structures in tropical climates which largely remain exposed to the action of alternating rains.

Dynamic analyses and field observations on piles in Kolkata city

Chatterjee, Kaustav,Choudhury, Deepankar,Rao, Vansittee Dilli,Mukherjee, S.P. Techno-Press 2015 Geomechanics & engineering Vol.8 No.3

In the present case study, High Strain Dynamic Testing of piles is conducted at 3 different locations of Kolkata city of India. The raw field data acquired is analyzed using Pile Driving Analyzer (PDA) and CAPWAP (Case Pile Wave Analysis Programme) computer software and load settlement curves along with variation of force and velocity with time is obtained. A finite difference based numerical software FLAC3D has been used for simulating the field conditions by simulating similar soil-pile models for each case. The net pile displacement and ultimate pile capacity determined from the field tests and estimated by using numerical analyses are compared. It is seen that the ultimate capacity of the pile computed using FLAC3D differs from the field test results by around 9%, thereby indicating the efficiency of FLAC3D as reliable numerical software for analyzing pile foundations subjected to impact loading. Moreover, various parameters like top layers of cohesive soil varying from soft to stiff consistency, pile length, pile diameter, pile impedance and critical height of fall of the hammer have been found to influence both pile displacement and net pile capacity substantially. It may, therefore, be suggested to include the test in relevant IS code of practice.

Potential use of nanotechnology in sustainable and ‘smart’ agriculture: advancements made in the last decade

Ranjita Ghosh Moulick,Sumistha Das,Nitai Debnath,Kaustav Bandyopadhyay 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.5

Ever since mankind embraced technology, the largest number of inventions have been aimed at agricultural improvement, more than any other sectors where technology is used. Nonetheless, today we are struggling to meet the ever increasing hunger of a growing world population. We have almost exhausted the supply of traditional technological ammunitions in the arsenal of agricultural science. The only way forward is to embrace smart agricultural practice in a sustainable manner. Use of modern electronics and material science to increase production, without further increasing fertilizer or pesticide input, can be referred to as smart and sustainable agriculture. Scientists have made giant leaps in the feld of ‘biology at nanoscale’ during the frst decade of the present century. Nanoparticles and nanosensors have huge potential in agricultural advancements, if used wisely with proper caution. Nanoparticles can be used for getting higher yield and for crop protection. Nanoparticles can also aid in the rate limiting process of gene delivery during genetic improvement of crop species. Nanobiosensors can contribute to smart farming by growth monitoring, real time detection of pests, and continuous monitoring of local environment. In this review, we will update the readers with some of the advancements made in these directions during the last decade.

Effect of Stone Columns on Strength and Consolidation Characteristics of Black Cotton Soil

Nitin Ishwarappa Bailappanavar,Mohit Kumar,Kaustav Chatterjee 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

One fifth of the land mass in India is covered by black cotton soil (BCS). Due to low permeability, poor strength and high compressibility, they pose huge engineering problems. In the present study, the influence of stone column on the consolidation and strength behaviour of black cotton soil is meticulously studied. Laboratory tests are carried out on both end bearing and floating type stone columns, having diameters (d) 50 mm, 60 mm and 70 mm with l/d ratios 3, 4 and 5 (l being the length of stone column), installed in black cotton soil. The load-settlement and consolidation behaviour of unreinforced and reinforced black cotton soil are compared. It has been found that for d = 60 mm and l/d = 3, the load carrying capacity for reinforced BCS increases by 23% and 20% for end bearing and floating type stone columns, respectively. Moreover the void ratio (e), coefficient of compressibility (av), coefficient of volume change (mv), coefficient of consolidation (Cv), coefficient of permeability (k) and compression index (Cc) of black cotton soils are significantly affected by the l/d ratio and diameter of the stone column. The present study reflects the efficiency of stone columns as suitable ground improvement technique for BCS.

A ‘Mixed’ Approach to Smart Group Formation in Collaborative Learning

Anal Acharya,Devadatta Sinha,Anurag Sarkar,Dibyabiva Seth,Kaustav Basu 한국산학기술학회 2015 SmartCR Vol.5 No.5

The most important aspect in collaborative learning is group formation. Over the years, researchers have proposed a variety of algorithms for collaborative group formation. Researchers have identified learner’s characteristics for this purpose like learning style, subject knowledge, preferred time slot, and domain expertise. Most of the generated groups were heterogeneous in nature. This study uses two parameters, the personal style of the learner and a performance indicator for collaborative group formation. Similar personal styles within a group were thought to facilitate group work, whereas a diverse degree of knowledge was thought to enhance the quality of learning. This ‘mixed’ approach was initially used to form homogeneous groups using K-means clustering. Heterogeneity was introduced within these groups through Agenda-driven search. An Automated Group Decomposition Program was written in Java platform using the developed model ,which was used to generate groups of students doing post-graduate workin Computer Science for their project work. T-test and survey results indicate that the proposed method is more effective for group formation than traditional methods.

Can platelet-rich plasma injections provide better pain relief and functional outcomes in persons with common shoulder diseases: a meta-analysis of randomized controlled trials

Apurba Barman,Archana Mishra,Rituparna Maiti,Jagannatha Sahoo,Kaustav Basu Thakur,Sreeja Kamala Sasidharan 대한견주관절학회 2022 대한견주관절의학회지 Vol.25 No.1

Background: To evaluate the efficacy of autologous platelet-rich plasma (PRP) injections in the treatment of common shoulder diseases. Methods: The PubMed, Medline, and Central databases and trial registries were searched from their inception to July 2020 for randomized controlled trials of autologous PRP injections for shoulder diseases versus placebo or any control intervention. Preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed in the selection, analysis, and reporting of findings. The primary outcome was pain intensity (visual analog scale), and secondary outcomes were changes in function and quality of life (QoL). Results: A total of 17 randomized controlled trials of PRP versus control were analyzed. From 8–12 weeks to ≥1 year, PRP injections were associated with better pain relief and functional outcomes than control interventions. PRP injections were also associated with greater QoL, with an effect size of 2.61 (95% confidence interval, 2.01–14.17) at medium-term follow-up. Compared with placebo and corticosteroid injections, PRP injections provide better pain relief and functional improvement. In subgroup analyses, trials in which PRP was prepared by the double centrifugation technique, the platelet concentration in the PRP was enriched ≥5 times, leucocyte-rich PRP was used, or an activating agent was used before application reported the most effective pain relief at 6–7 months. Conclusions: PRP injections could provide better pain relief and functional outcomes than other treatments for persons presenting with common shoulder diseases. PRP injections have a greater capacity to improve shoulder-related QoL than other interventions.

Genome-wide identification of auxin response factors (ARFs) in three different species of Arachis

Raul Bikash,Bhattacharjee Oindrila,Tembhare Kunal,Khanna Tanyya,Shaheen Tarannum,Sinharoy Senjuti,Bandyopadhyay Kaustav 한국식물생명공학회 2021 Plant biotechnology reports Vol.15 No.2

The phytohormone auxin is involved in the regulation of plant growth, nutrient acquisition, and response to environmental stimuli. Auxin response factors (ARFs) are transcription factors containing B3 DNA binding domain. ARFs play central role in auxin response, using Aux/IAA proteins as partners. Arachis is a genus within the Dalbergioid clade of papilionoid legumes, which out-branched from other members of papilionoids. Cultivated peanut (Arachis hypogaea L.) is an allotetraploid formed by hybridization of two parental genotypes Arachis duranensis, and Arachis ipaensis merely 10,000 years ago. We have made a genome-wide inventory of all the ARFs present in tetraploid A. hypogaea, as well as in two diploid parental genotypes. Our data show that Arachis contains more ARFs per diploid genome (around 31), compared to other legumes (around 25). We further observed few ARF-like genes which are defective in important domains. Most of the ARFs in tetraploid Arachis are redundant, representing the A and B sub-genomes. Some of the ARFs show expression bias from either A or B sub-genome, while some of the pairs are expressed from both sub-genomes. Many ARFs do not express in any of the conditions for which we have expression data. Finally, few pairs show diferential spatio-temporal expression pattern from A and B sub-genomes, indicative of diversifcation of function. This is the frst efort to list all the ARFs from an allotetraploid legume. The list of ARFs in all three species of Arachis will help the scientifc community working to understand auxin regulation in crop legumes. The phytohormone auxin is involved in the regulation of plant growth, nutrient acquisition, and response to environmental stimuli. Auxin response factors (ARFs) are transcription factors containing B3 DNA binding domain. ARFs play central role in auxin response, using Aux/IAA proteins as partners. Arachis is a genus within the Dalbergioid clade of papilionoid legumes, which out-branched from other members of papilionoids. Cultivated peanut (Arachis hypogaea L.) is an allotetraploid formed by hybridization of two parental genotypes Arachis duranensis, and Arachis ipaensis merely 10,000 years ago. We have made a genome-wide inventory of all the ARFs present in tetraploid A. hypogaea, as well as in two diploid parental genotypes. Our data show that Arachis contains more ARFs per diploid genome (around 31), compared to other legumes (around 25). We further observed few ARF-like genes which are defective in important domains. Most of the ARFs in tetraploid Arachis are redundant, representing the A and B sub-genomes. Some of the ARFs show expression bias from either A or B sub-genome, while some of the pairs are expressed from both sub-genomes. Many ARFs do not express in any of the conditions for which we have expression data. Finally, few pairs show diferential spatio-temporal expression pattern from A and B sub-genomes, indicative of diversifcation of function. This is the frst efort to list all the ARFs from an allotetraploid legume. The list of ARFs in all three species of Arachis will help the scientifc community working to understand auxin regulation in crop legumes.