Structural damage detection through longitudinal wave propagation using spectral finite element method

Kumar, K. Varun,Saravanan, T. Jothi,Sreekala, R.,Gopalakrishnan, N.,Mini, K.M. Techno-Press 2017 Geomechanics & engineering Vol.12 No.1

This paper investigates the damage identification of the concrete pile element through axial wave propagation technique using computational and experimental studies. Now-a-days, concrete pile foundations are often common in all engineering structures and their safety is significant for preventing the failure. Damage detection and estimation in a sub-structure is challenging as the visual picture of the sub-structure and its condition is not well known and the state of the structure or foundation can be inferred only through its static and dynamic response. The concept of wave propagation involves dynamic impedance and whenever a wave encounters a changing impedance (due to loss of stiffness), a reflecting wave is generated with the total strain energy forked as reflected as well as refracted portions. Among many frequency domain methods, the Spectral Finite Element method (SFEM) has been found suitable for analysis of wave propagation in real engineering structures as the formulation is based on dynamic equilibrium under harmonic steady state excitation. The feasibility of the axial wave propagation technique is studied through numerical simulations using Elementary rod theory and higher order Love rod theory under SFEM and ABAQUS dynamic explicit analysis with experimental validation exercise. Towards simulating the damage scenario in a pile element, dis-continuity (impedance mismatch) is induced by varying its cross-sectional area along its length. Both experimental and computational investigations are performed under pulse-echo and pitch-catch configuration methods. Analytical and experimental results are in good agreement.

Highly Efficient Organic Photocatalysts Discovered via a Computer-aided-design Strategy for Visible-light-driven Atom Transfer Radical Polymerization

Varun Kumar Singh,유창훈,김영무,권용환,김도연,이준혁,권민상 한국고분자학회 2018 한국고분자학회 학술대회 연구논문 초록집 Vol.43 No.2

Supranuclear oculomotor palsy in cerebral venous sinus thrombosis: a case report

Kumar Bismaya,Sabyasachi Pattanayak,Abhishek Dixit,Abhishek Pathak,Rameshwar Nath Chaurasia,Varun Kumar Singh 대한신경집중치료학회 2021 대한신경집중치료학회지 Vol.14 No.2

BackgroundFor certain ocular movement abnormalities, the exact neuroanatomical localization of the causative lesion is still not defined. Oculomotor apraxia, apraxia of eye opening and closing, and motor impersistence are rarely reported in acute stroke, particularly following venous stroke.Case ReportA 34-year-old man presented with headache, vomiting, focal seizures with bilateral tonic-clonic movements, and altered sensorium. Magnetic resonance imaging revealed bilateral frontal and left parietal hemorrhagic infarcts, and contrast venography revealed superior sagittal sinus thrombosis. The patient received anticoagulant treatment with antiepileptics. On re-examination on day 3, the patient had a rare combination of apraxia of eyelid closure, motor impersistence, and oculomotor apraxia. By Day 10 of admission, all oculomotor abnormalities had subsided.ConclusionTo the best of our knowledge, this is the first report of the combination of oculomotor apraxia and apraxia of eyelid closure with motor impersistence in a patient with cerebral venous sinus thrombosis.

Inhibitory Activity of Oak Pyroligneous Liquor against Coleosporium Plectranthi, an Obligate Parasite Responsible for the Rust Disease on Perilla Leaf

Kumar, Varun,Chauhan, Anil Kumar,Baek, Kwang-Hyun,Kang, Sun-Chul The Korean Society of Environmental Agriculture 2011 한국환경농학회지 Vol.30 No.4

BACKGROUND: Coleosporium plectranthi, an obligate parasite, which is responsible for the rust disease of Perilla frutescens, a plant in Korea, commonly known as Perilla. All rusts are obligate parasites, meaning that they require a living host to complete their life cycle. They generally do not kill the host plant but can severely reduce growth and yield. Food and feed spoilage fungi cause great economic losses worldwide. It is estimated that between 5 and 10% of the world food production is wasted due to fungal deterioration. Rust disease of Perilla is highly frequent and is widely spread in Korea. The present study was designed to investigate a novel media for the urediniospore germination in vitro and anti-rust activity as well as GC-MS analysis of oak pyroligneous liquor. METHOD AND RESULTS: Urediniospores were collected from the infected leaf of Perilla. Spore suspension was made and the suspension was inoculated in the 2% water agar media with proper humidity, then they were incubated at $26^{\circ}C$ for 56 hrs. The GC-MS analysis of the oak pyroligneous liquor was also done to check the chemical composition. GC-MS analysis of the wood vinegar was found 15 compounds, among them o-mthoxyphenol (25.93%), 2,6-dimethoxyphenol (16.06%), 4-methylenecyclohexanone (10.69%), 2,3-dihydroxytoluene (7.84%), levoglucosane (6.14%) and propanoic acid (5.32%) were the major components. Different concentration of the oak pyroligneous liquor was used, and spore inhibition was recorded on the basis of spore counting. The best results were noted at the concentration of 50% solution where 31.8% spores were inhibited. CONCLUSION: On the basis of the chemical composition of the oak pyroligneous liquor and the activity recorded we can use it as an anti-rust agent.

Inhibitory Activity of Oak Pyroligneous Liquor against Coleosporium Plectranthi, an Obligate Parasite Responsible for the Rust Disease on Perilla Leaf

( Varun Kumar ),( Anil Kumar Chauhan ),( Kwang Hyun Baek ),( Sun Chul Kang ) 한국환경농학회 2011 한국환경농학회지 Vol.30 No.4

BACKGROUND: Coleosporium plectranthi, an obligate parasite, which is responsible for the rust disease of Perilla frutescens, a plant in Korea, commonly known as Perilla. All rusts are obligate parasites, meaning that they require a living host to complete their life cycle. They generally do not kill the host plant but can severely reduce growth and yield. Food and feed spoilage fungi cause great economic losses worldwide. It is estimated that between 5 and 10% of the world food production is wasted due to fungal deterioration. Rust disease of Perilla is highly frequent and is widely spread in Korea. The present study was designed to investigate a novel media for the urediniospore germination in vitro and anti-rust activity as well as GC-MS analysis of oak pyroligneous liquor. METHOD AND RESULTS: Urediniospores were collected from the infected leaf of Perilla. Spore suspension was made and the suspension was inoculated in the 2% water agar media with proper humidity, then they were incubated at 26℃ for 56 hrs. The GC-MS analysis of the oak pyroligneous liquor was also done to check the chemical composition. GC-MS analysis of the wood vinegar was found 15 compounds, among them o-mthoxyphenol (25.93%), 2,6- dimethoxyphenol (16.06%),4-methylenecyclohexanone (10.69%), 2,3-dihydroxytoluene (7.84%), levoglucosane (6.14%) and propanoic acid (5.32%) were the major components. Different concentration of the oak pyroligneous liquor was used, and spore inhibition was recorded on the basis of spore counting. The best results were noted at the concentration of 50% solution where 31.8% spores were inhibited. CONCLUSION: On the basis of the chemical composition of the oak pyroligneous liquor and the activity recorded we can use it as an anti-rust agent.

A novel pectoral muscle segmentation from scanned mammograms using EMO algorithm

Santhos Kumar Avuti,Varun Bajaj,Anil Kumar,Girish Kumar Singh 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.4

Mammogram images are majorly used for detecting the breast cancer. The level of positivity of breast cancer is detected afterexcluding the pectoral muscle from mammogram images. Hence, it is very signifi cant to identify and segment the pectoralmuscle from the mammographic images. In this work, a new multilevel thresholding, on the basis of electro-magnetismoptimization (EMO) technique, is proposed. The EMO works on the principle of attractive and repulsive forces among thecharges to develop the members of a population. Here, both Kapur’s and Otsu based cost functions are employed with EMOseparately. These standard functions are executed over the EMO operator till the best solution is achieved. Thus, optimalthreshold levels can be identifi ed for the considered mammographic image. The proposed methodology is applied on all thethree twenty-two mammogram images available in mammographic image analysis society dataset, and successful segmentationof the pectoral muscle is achieved for majority of the mammogram images. Hence, the proposed algorithm is found tobe robust for variations in the pectoral muscle.

Clinical spectrum of elderly-onset inflammatory bowel disease in India

Yogesh Kumar Gupta,Arshdeep Singh,Vikram Narang,Vandana Midha,Ramit Mahajan,Varun Mehta,Dharmatma Singh,Namita Bansal,Madeline Vithya Barnaba Durairaj,Amit Kumar Dutta,Ajit Sood 대한장연구학회 2023 Intestinal Research Vol.21 No.2

Background/Aims: Inflammatory bowel disease (IBD) is increasingly being recognized in elderly patients. Data on clinical spectrum of elderly-onset IBD patients is lacking from India. Methods: A cross-sectional retrospective analysis of a prospectively maintained database of patients diagnosed with IBD was conducted at 2 centers in India. The clinical spectrum of elderly-onset IBD including demographic profile (age and sex), clinical presentation, disease characteristics (disease behavior and severity, extent of disease), and treatment were recorded and compared with adult-onset IBD. Results: During the study period, 3,922 (3,172 ulcerative colitis [UC] and 750 Crohn’s disease [CD]) patients with IBD were recorded in the database. A total of 186 patients (4.74%; 116 males [62.36%]) had elderly-onset IBD (69.35% UC and 30.64% CD). Diarrhea, blood in stools, nocturnal frequency and pain abdomen were the commonest presentations for UC, whereas pain abdomen, weight loss and diarrhea were the most frequent symptoms in CD. For both elderly onset UC and CD, majority of the patients had moderately severe disease. Left-sided colitis was the commonest disease location in UC. Isolated ileal disease and inflammatory behavior were the most common disease location and behavior, respectively in CD. 5-Aminosalicylates were the commonest prescribed drug for both elderly onset UC and CD. Thiopurines and biologics were used infrequently. Prevalence of colorectal cancer was higher in elderly onset IBD. Conclusions: Elderly onset IBD is not uncommon in India. Both the elderly onset UC and CD were milder, with no significant differences in disease characteristics (disease extent, location and behavior) when compared to adult-onset IBD. Colorectal cancer was more common in elderly onset IBD.

Effect of Chemical Fertilizer-adaptive Variants, Pseudomonas aeruginosa GRC2 and Azotobacter chroococcum AC1,on Macrophomina phaseolina Causing Charcoal Rotof Brassica juncea

Kishore Kumar Joshi,강선철,Varun Kumar,Ramesh Chand Dubey,Dinesh Kumar Maheshwari,Vivek K. Bajpai 한국환경농학회 2006 한국환경농학회지 Vol.25 No.3

Pseudomonas aeruginosa GRC2, siderophore-producing strain, inhibited growth of Macrophomina phaseolina in vitro and reduced charcoal rot in seeds of Brassica juncea in field when coated with adaptive strains. P. aeruginosa GRC2 and Azotobacter chroococcum AC1 produced indole-3-acetic acid and solubilized insoluble phosphate. A. chroococcum AC1 fixed nitrogen asymbiotically. Urea and diammonium phosphate- adaptive variant strains of P. aeruginosa and A. chroococcum strongly inhibited M. phaseolina in comparison to parental strains. Bacterization of seeds induced seed germination, seedling growth, and enhanced yield of B. juncea by 10.87% as compared to full doses of urea and diammonium phosphate. Both adaptive strains of chemical fertilizers aggressively colonized roots, showing effectiveness to growth and developments of B. juncea.

A parametric study of the 2D model of solar air heater with elliptical rib roughness using CFD

Rajneesh Kumar,Varun Geol,Anoop Kumar 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

The heat transfer can be improved by providing artificial roughness on absorber plate of the solar air heat. Many studies are available on circular, semi-circular, triangular and rectangular rib roughened solar air heater. But in present study heat transfer enhancement by providing elliptical ribs on absorber plate was analyzed by developing CFD code on non-commercial ANSYS (Fluent) 12.1 software. The simulations were performed on 2-D CFD model and analysis was carried out to study the effect of relative roughness width, relative roughness height and relative roughness pitch on heat transfer and friction factor. The Reynolds number range from 4000 to 15000 and turbulence phenomena is modeled by using Reynolds-average Navier-Stokes equations (RANS). The mathematical modeling is validated and compared with available results. The strong vortex formation takes place in the main stream flow because of elliptical roughness, which improved heat transfer augmentation in the solar air heater. The local turbulence kinetic energy strongly influenced by orientation of the elliptical ribs. The value of average Nusselt number increases by increasing relative roughness height but it decreases with the increase of relative roughness width and relative roughness pitch. The rib width has significant effects on heat transfer enhancement and maximum Nusselt number is observed for relatively small roughness width (i.e., 0.5) among the considered range of 0.5 mm to 2.0 mm. The maximum value of Nusselt number and friction factor is observed for relative roughness width of 0.5, relative roughness height of 0.045, and relative roughness pitch of 6.

Numerical investigation of heat transfer and friction factor in ribbed triangular duct solar air heater using Computational fluid dynamics (CFD)

Rajneesh Kumar,Varun Goel,Anoop Kumar,Sourabh Khurana,Paramvir Singh,Santosh B. Bopche 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

The Computational fluid dynamics (CFD) based analysis is carried out to investigate the thermal and hydraulic performance of circular rib roughened triangular passage Solar air heater (SAH). The circular ribs were provided over the absorber plate. The roughness parameter such as relative roughness pitch (P/e) and relative roughness height (e/D) varies from 4 to 20 and 0.015 to 0.06 (in four sets), respectively, the Reynolds number (Re) varies from 4000 to 18000. The flow governing equations were solved using commercial ANSYS (Fluent) software. The predicted Nusselt number (Nu) and friction factor (f) are validated with the available experimental results. The thermal and hydraulic performance of roughened duct is estimated in the form of Nusselt number and friction factor, respectively. The Thermohydraulic performance parameter (TPP) is also evaluated depending on the friction factor (f) and Nusselt number (Nu) values for SAH. The maximum Thermohydraulic performance parameter (TPP) is observed at Reynolds number of 15000 in case of relative roughness pitch (P/e) and relative roughness height (e/D) value of 12 and 0.06, respectively.