Performance assessment of RC frame designed using force, displacement & energy based approach

Onkar G. Kumbhar,Ratnesh Kumar 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.6

Force based design (FBD) approach is prevalent in most of the national seismic design codes world over. Direct displacement based design (DDBD) and energy based design (EBD) approaches are relatively new methods of seismic design which claims to be more rational and predictive than the FBD. These three design approaches are conceptually distinct and imparts different strength, stiffness and ductility property to structural members for same plan configuration. In present study behavioural assessment of frame of six storey RC building designed using FBD, DDBD and EBD approaches has been performed. Lateral storey forces distribution, reinforcement design and results of nonlinear performance using static and dynamic methods have been compared. For the three approaches, considerable difference in lateral storey forces distribution and reinforcement design has been observed. Nonlinear pushover analysis and time history analysis results show that in FBD frame plastic deformation is concentrated in the lower storey, in EBD frame large plastic deformation is concentrated in the middle storeys though the inelastic hinges are well distributed over the height and, in DDBD frame plastic deformation is approximately uniform over the height. Overall the six storey frame designed using DDBD approach seems to be more rational than the other two methods.

Probabilistic free vibration analysis of Goland wing

Kumar, Sandeep,Onkar, Amit Kumar,Manjuprasad, M. The Society for Aerospace System Engineering 2019 International Journal of Aerospace System Engineer Vol.6 No.2

In this paper, the probabilistic free vibration analysis of a geometrically coupled cantilever wing with uncertain material properties is carried out using stochastic finite element (SFEM) based on first order perturbation technique. Here, both stiffness and damping of the system are considered as random parameters. The bending and torsional rigidities are assumed as spatially varying second order Gaussian random fields and represented by Karhunen Loeve (K-L) expansion. Here, the expected value, standard deviation, and probability distribution of random natural frequencies and damping ratios are computed. The results obtained from the present approach are also compared with Monte Carlo simulations (MCS). The results show that the uncertain bending rigidity has more influence on the damping ratio and frequency of modes 1 and 3 while uncertain torsional rigidity has more influence on the damping ratio and frequency of modes 2 and 3.

Enhancement of combined cycle performance using transpiration cooling of gas turbine blades with steam

Sanjay Kumar,Onkar Singh 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6

Gas/steam combined cycle is synergetic combination of Brayton cycle based topping cycle and Rankine cycle based bottoming cycle,which have capability of operating independently too. Combined cycle performance depends on the constituent cycles and it can be reasonablyimproved by enhancing gas cycle performance using gas turbine blade cooling. Amongst different cooling techniques the transpirationcooling offers effective utilization of coolant as compared to film cooling because of better shrouding of blade surface as thecoolant is discharged from entire blade surface. The present work deals with evaluation of performance enhancement of combined cycleby using steam transpiration cooling of gas turbine blades. The combined cycle performance parameters e.g. overall efficiency and specificpower output etc. have been compared for air transpiration cooling and steam transpiration cooling. The results revealed that for thespecified conditions the steam is superior coolant in comparison to air and the combined cycle performance can be enhanced by applyingtranspiration cooling in gas turbine blades with steam as coolant. With a turbine inlet temperature of 1800 K and compressor pressureratio of 23, the combined cycle efficiency with steam transpiration cooling of gas turbine blades is higher by 1.94 percent approximatelyas compared to the efficiency of combined cycle with air transpiration cooling of gas turbine blades.

Simplified beam-column joint model for reinforced concrete moment resisting frames

Kanak Parate,Onkar Kumbhar,Ratnesh Kumar 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.1

During strong seismic events, inelastic shear deformation occurs in beam-column joints. To capture inelastic shear deformation, an analytical model for beam-column joint in reinforced concrete (RC) frame structures has been proposed in this study. The proposed model has been developed using a rotational spring and rigid links. The stiffness properties of the rotational spring element have been assigned in terms of a moment rotation curve developed from the shear stress-strain backbone curve. The inelastic rotation behavior of joint has been categorized in three stages viz. cracking, yielding and ultimate. The joint shear stress and strain values at these stages have been estimated using analytical models and experimental database respectively. The stiffness properties of joint rotational spring have been modified by incorporating a geometry factor based on dimensions of adjoining beam and column members. The hysteretic response of the joint rotational spring has been defined by a pivot hysteresis model. The response of the proposed analytical model has been verified initially at the component level and later at the structural level with the two actually tested RC frame structures. The proposed joint model effectively emulates the inelastic behavior precisely with the experimental results at component as well as at structural levels.

Treatment of Oral Leukoplakia with Diode Laser: a Pilot Study on Indian Subjects

Kharadi, Usama A Rashid,Onkar, Sanjeev,Birangane, Rajendra,Chaudhari, Swapnali,Kulkarni, Abhay,Chaudhari, Rohan Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.18

Background: To evaluate the safety, convenience and effectiveness of 940nm diode laser for treatment of homogenous leukoplakia. Materials and Methods: Ten patients having homogenous leukoplakia which were diagnosed clinically were selected from an Indian dental educational institution for the study. Toludine blue staining was applied locally over the lesion. The area where there was increased uptake of stain was excised using a 940 nm EZLASE TM diode laser (BIOLASE-USA). Results: Although various treatment modalities have been tried and the search continues for novel treatment modalities for complete removal of homogenous leukoplakia, from results of our preliminary pilot study it is clear that the use of 940 nm diode laser as a treatment modality for homogenous leukoplakia is a good substitute. Healing was perfect without any complication within a duration of 1 month. Pain intensity was also mild and absolutely zero on the VAS scale after 1 month follow up. Conclusions: 940 nm diode lasers are safe and can be effectively used as a treatment modality of homogenous leukoplakia, without any complication and without compromising health and oral function of patients. Considering recurrence factor, long term follow up for patients is a must.

A Note on Semi-Closed Graph

Lee,Je-Yoon,Panwar,Onkar Singh,Dube,K.K. 울산대학교 1983 연구논문집 Vol.14 No.2

이 논문에서 사상이 반폐그래프를 갖기 위한 여러가지 조건들을 알아본다. 사상이 폐그래프를 가지면 그 그래프는 반폐 그래프이나, 그 역은 성립하지 않음을 보인다. 또 이미 알려진 몇 개의 사상들이 반폐 그래프를 갖지 못하는 것을 보이고, 반면, 반폐 그래프를 가져도 항상 좋은 형의 사상이 되지 않음을 보였다. In this note, various conditions are discussed under which a mapping has a semi-closed graph. If a mapping has a closed graph, then, clearly, its graph is semi0closed but not conversely (Exmaple 1). It is shown that, on one hand, various types of some known mappings may fail to have semi-closed graphs and, on the other hand, a mapping having semi-closed graph may fail to be some 'nice' types of mappings.

Performance Evaluation of Solar Energy Driven Diffusion Absorption Refrigeration Cycle Using Inorganic Fluid Pair

Kishan Pal Singh,Onkar Singh 대한설비공학회 2018 International Journal Of Air-Conditioning and Refr Vol.26 No.4

In the present era, the refrigeration and air conditioning have become essential requirements, and consume significant portion of energy available. The refrigeration requirements are severe in the hot and humid countries and, the refrigeration systems based upon solar energy are desirable. This study focuses on the thermodynamic modelling of ammonia water diffusion absorption refrigeration cycle with helium as pressure equalizing gas. The performance of the cycle is investigated parametrically by computer simulation based on thermodynamic modeling. It is found that the performance shows a loss of 37.36% at 110 ∘ C while only 23.52% at 140∘C a generator temperature in the range of 120 to 150 ∘ C is best suited for ammonia concentration range of 0.25–0.45 to get optimum performance.

Evaluation of Dimensions of Kambin's Triangle to Calculate Maximum Permissible Cannula Diameter for Percutaneous Endoscopic Lumbar Discectomy : A 3-Dimensional Magnetic Resonance Imaging Based Study

Pairaiturkar, Pradyumna Purushottam,Sudame, Onkar Shekhar,Pophale, Chetan Shashikant The Korean Neurosurgical Society 2019 Journal of Korean neurosurgical society Vol.62 No.4

Objective : To evaluate 3-dimensional magnetic resonance imaging (MRI) of Kambin's safe zone to calculate maximum cannula diameter permissible for safe percutaneous endoscopic lumbar discectomy. Methods : Fifty 3D MRIs of 19 males and 31 females (mean, 47 years) were analysed. Oblique, axial and sagittal views were used for image analysis. Three authors calculated the inscribed circle (cannula diameter) individually, within the neural (original) and bony Kambin's triangle in oblique views, disc heights on sagittal views and root to facet distances at upper and lower end plate levels on axial views and their averages were taken. Results : The mean root to facet distances at upper end plate level measured on axial sections increased from $3.42{\pm}3.01mm$ at L12 level to $4.57{\pm}2.49mm$ at L5S1 level. The mean root to facet distances at lower end plate level measured on axial sections also increased from $6.07{\pm}1.13mm$ at L12 level to $12.9{\pm}2.83mm$ at L5S1 level. Mean maximum cannula diameter permissible through the neural Kambin's triangle increased from $5.67{\pm}1.38mm$ at L12 level to $9.7{\pm}3.82mm$ at L5S1 level. The mean maximum cannula diameter permissible through the bony Kambin's triangle also increased from $4.03{\pm}1.08mm$ at L12 level to $6.11{\pm}1mm$ at L5S1 level. Only 2% of the 427 bony Kambin's triangles could accommodate a cannula diameter of 8mm. The base of the bony Kambin's triangle taken in oblique view (3D MRI) was significantly higher than the root to facet distance at lower end plate level taken in axial view. Conclusion : The largest mean diameter of endoscopic cannula passable through "bony" Kambin's triangle was distinctively smaller than the largest mean diameter of endoscopic cannula passable through "neural" Kambin's triangle at all levels. Although proximity of exiting root to the facet joint is always taken into consideration before PELD procedure, our 3D MRI based anatomical study is the first to provide actual maximum cannula dimensions permissible in this region.

Placental Histopathology in COVID-19-Positive Mothers

Sherwani Nikita,Singh Neha,Neral Arvind,Jaiswal Jyoti,Nagaria Tripti,Khandwal Onkar 한국미생물·생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.9

The placenta is a captivating multifunctional organ of fetal origin and plays an essential role during pregnancy by intimately connecting mother and baby. This study explicates placental pathology and information about 25 placentas collected from the mothers infected with novel coronavirus (SARS-COV-2). So far, congenital transmission of SARS-CoV-2 seems to be remarkably uncommon in spite of many cases of COVID-19 during pregnancy. Out of the 25 placental tissue samples collected, none has shown gene expression of SARS-CoV-2 when confirmed by RT-PCR. At the same time, nasal and throat swab samples collected from newborns of SARS-CoV-2-positive mothers correspondingly tested negative by RT-PCR. The shielding properties of placental barriers against viral infections from mothers to newborns remains a mystery. Major histopathological findings have been recorded as choriodecidual tissue with necrosis, intramural fibrin deposition, chorionic villi with fibrosis, and calcification. Moreover, although recent findings are insufficient to prove direct placental transmission of COVID-19, the abundance of angiotensin-converting enzymes-2 (ACE-2) on the placental surface could potentially contribute to unpleasant outcomes during pregnancy as SARSCoV- 2 gains access to human cells via ACE-2. Finally, the significance of these findings is vague and needs further study.

Investigation of structural phase transition, Curie temperature and energy storage density of Ba0.97Ca0.03Ti1−xSnxO3 electroceramics

Kadhane Pravin S.,Baraskar Bharat G.,Darvade Tulshidas C.,Ramdasi Onkar A.,Samsuzzaman Md.,Kambale Rahul C. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5

Three different measurement methods to determine the structural phase transitions and Curie temperature of Ba 0.97 Ca 0.03 Ti 1−x Sn x O 3 (BCTS, x = 0.025, and 0.035 mol). electroceramics are discussed. At room temperature, both com- positions reveal the tetragonal perovskite lattice symmetry as evidenced by X-ray diffraction, temperature-dependent dielectric constant and Raman active modes. The temperature-dependent dielectric study reveals T R-O at − 60 °C, T O-T at 14 °C, T T-C at 126 °C for composition x = 0.025 and T R-O at − 50 °C, T O-T at 20 °C, T T-C at 118 °C for composition x = 0.035. To evident the structural changes happening at phase transitions as well as Curie temperature the variation of polarization concerning temperature is investigated which supports the temperature-dependent dielectric and Raman spectroscopy studies. The room temperature recoverable energy storage density and efficiency of BCTS are calculated by the integral area 3 of the polarization–electric fi eld (P-E) hysteresis loop. The observed recoverable energy storage density is 21.80 mJ/cm and 32.40 mJ/cm 3 with the efficiency of 43.58% and 52.25% for composition x = 0.025 and 0.035 mol., respectively. These results are having practical importance, due to the higher recoverable energy storage density and efficiency with moderate Curie temperature compared to the pure BaTiO 3 . Thus, it can be used as a promising novel and environmentally friendly, lead-free material, for different applications in low carbon vehicles, renewable energy technologies, integrated circuits, and for the high-temperature aerospace sector.