Laminar flame speeds for n-butanol/air mixtures at elevated pressures and temperatures: An experimental and numerical study

Niladri Talukder,이기용 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4

Laminar flame speeds of n-butanol/air premixed flames were measured experimentally and numerically at elevated pressures and temperatures for a wide range of equivalence ratios. Laminar flame speeds were obtained experimentally from the temporal evaluation of the flame front of spherically outwardly propagating flames at zero stress rate. The shadowgraph technique was employed to gain optical access to the constant volume combustion chamber. Flame propagation images were captured by a high-speed camera and MATLAB codes were used to process the images and calculate laminar flame speeds. Flame speeds have been calculated numerically using CHEMKIN-Pro based on a short reaction mechanism for n-butanol oxidation, which was derived from a previously published full reaction mechanism. Numerical predictions were in qualitative agreement with experimental data. The effects of initial pressure and temperature elevation were analyzed. Also, the effect of simultaneous elevation of initial pressures and temperatures is documented. For all experimental conditions, the maximum flame speed was found at around equivalence ratio 1.1. In general, flame speeds decreased with the elevation of initial pressure and increased with initial temperature elevation.

Re-examining the Spectrum of Lumbosacral Transitional Dysmorphisms: Quantifying Joint Asymmetries and Evaluating the Anatomy of Screw Fixation Corridors

Niladri Kumar Mahato 대한척추신경외과학회 2020 Neurospine Vol.17 No.1

Objective: Although a wide range of sacral dysmorphisms has been documented with lumbosacral transitional vertebrae (LSTV) variations, quantitative characterization of the upper segment morphology and articular anatomy across the array of lumbosacral transitions are hardly found in the literature. This study presents LSTV anomalies as a series of sequential morphological changes (the LSTV spectrum) and quantitatively compares 6 LSTV subtypes with normative sacral dimensions including the anatomy at the upper sacral segments used for percutaneous sacroiliac screw insertion. Methods: Seven linear dimensions were measured from LSTV subtypes and normal sacral variants from dried adult sacral specimens. The auricular, superior articular and facet surface areas were quantified. Obliquity and thickness of osseous corridors used for sacroiliac screw fixation were measured. Data were statistically compared within and between LSTV subtypes and the normal variants. Results: LSTVs presented a wide range of morphometric differences in comparison to the normal bones. Grouping LSTV according to auricular surface positions (high, normal, and low) demonstrated significant between-group differences in the obliquity and thickness at the S1 and S2 segmental corridors. Conclusion: Frequent occurrence of LSTV in the general population may require evaluation of anatomical parameters in these variations for safe sacroiliac instrumentation around this region.

Assessment of In Vivo Lumbar Inter-Vertebral Motion: Reliability of a Novel Dynamic Weight-Bearing Magnetic Resonance Imaging Technique Using a Side-Bending Task

Niladri Kumar Mahato,Stephane Montuelle,Brian C. Clark 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.3

Study Design: Between-session reliability of a magnetic resonance imaging (MRI) based experimental technique to quantify lumbar inter-vertebral motion in humans. Purpose: We have developed a novel, dynamic, MRI-based approach for quantifying in vivo lumbar inter-vertebral motion. In this study, we present the protocol’s reliability results to quantify inter-vertebral spine motion. Overview of Literature: Morphometric studies on intervertebral displacements using static, supine MRI and quantification of dynamic spine motion using different X-ray based radiography techniques are commonly found in the literature. However, reliability testing of techniques assessing real-time lumbar intervertebral motion using weight-bearing MRI has rarely been reported. Methods: Ten adults without a history of back pain performed a side-bending task on two separate occasions, inside an open-MRI, in a weight-bearing, upright position. The images were acquired during the task using a dynamic magnetic resonance (MR) sequence. The MRI imaging space was externally calibrated before the study to recreate the imaging volume for subsequent use in an animation software. The dynamic MR images were processed to create side-bending movement animations in the virtual environment. Participant-specific three-dimensional models were manually superimposed over vertebral image silhouettes in a sequence of image frames, representing the motion trials. Inter-vertebral axes and translation and rotational displacements of vertebrae were quantified using the animation software. Results: Quantification of inter-vertebral rotations and translations shows high reliability. Between-session reliability results yielded high values for the intra-class correlation coefficient (0.86–0.93), coefficient of variation (13.3%–16.04%), and Pearson’s correlation coefficients (0.89–0.98). Conclusions: This technique may be developed further to improve its speed and accuracy for diagnostic applications, to study in vivo spine stability, and to assess outcomes of surgical and non-surgical interventions applied to manage pathological spine motion.

Experimental Measurement of Laminar Flame Velocity of n-Butanol-Air Premixed Flame at High Pressure and Temperature

Niladri Talukder,Ki Yong Lee(이기용) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.12

Lumbar Spine Anatomy in Supine versus Weight- Bearing Magnetic Resonance Imaging: Detecting Significant Positional Changes and Testing Reliability of Quantification

Mahato Niladri Kumar,Maharaj Paramanand,Clark Brian C. 대한척추외과학회 2024 Asian Spine Journal Vol.18 No.1

Study Design: Testing between and within group differences and assessing reliability of measurements. Purpose: To study and compare lumbar spine morphology in supine and weight-bearing (WB) magnetic resonance imaging (MRI). Overview of Literature: Upright lumbar MRI may uncover anatomical changes that may escape detection when using conventional supine imaging. This study quantified anatomical dimensions of the lumbar spine in the supine and WB MRI, compared specific morphometric differences between them, and tested the intra-rater reliability of the measurements. Repeated measures analysis was used to compare within- and between-session measurements performed on the supine and WB images. Reliability and agreement were assessed by calculating intraclass correlation (ICC) coefficient. Methods: Data from 12 adults without any history of back pain were used in this study. Sagittal T2-weighted images of the lumbar spine were acquired in the supine and WB positions twice (in two separate sessions scheduled within a week). Linear, angular dimensions, and cross-sectional areas (CSAs) were measured using proprietary software. Supine and WB data acquired from the two imaging sessions were tested for intra-rater reliability. Quantified data were normalized for each session to test the significance of differences. ICC was calculated to test the reliability of the measurements. Results: Linear, angular, and CSA measurements demonstrated strong within-position (supine and WB) correlations (r-values, 0.75–0.97). Between-position (supine vs. WB) differences were significant for all measured dimensions (p<0.05). Between-session measurements demonstrated a strong correlation (r-values, 0.64–0.83). Calculated ICC showed strong agreement among the measurements. Conclusions: Anatomical dimensions of the lumbar spine may demonstrate consistent and significant differences between supine and WB MRI for specific structural parameters.

Laminar flame speeds and Markstein lengths of methyl decanoate-air premixed flames at elevated pressures and temperatures

Talukder, Niladri,Lee, Ki Yong Elsevier 2018 Fuel Vol.234 No.-

<P><B>Abstract</B></P> <P>Laminar flame speeds and Markstein lengths of methyl decanoate (MD)-air mixtures were measured within a range of equivalence ratio at different elevated pressures and temperatures using outwardly propagating spherical flames developed inside a constant volume combustion chamber. Shadowgraph technique was employed to observe the temporal evolution of flame fronts. A numerical scheme was used to justify all the experimental data of laminar flame speeds. The numerical scheme was developed based on a short mechanism of methyl decanoate oxidation. A sound agreement was observed between the numerical predictions and experimentally obtained data of laminar flame speeds. Markstein lengths were calculated to quantify the effect of stretch on the flame front at different initial conditions. The study provided viable data of laminar flame speeds and Markstein lengths of methyl decanoate-air flames at different initial conditions which were also well conforming to the established theories of conventional fuels regarding of the effects of equivalence ratio, pressure, and temperature variation on laminar flame speed.</P>

Remote Position Control System of Stepper Motor Using DTMF Technology

Sagarika Pal,Niladri S. Tripathy 보안공학연구지원센터 2011 International Journal of Control and Automation Vol.4 No.2

Investigation of As‑Cast and Homogenized Microstructure in Mg–6 wt% Sn–1 wt% Al Alloy: An Experimental and Modelling Study

Ashutosh Jena,Niladri Naskar,Nishant Kumar,Manas Paliwal 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

A wedge casting experiment was performed for ternary Mg–6 wt% Sn–1 wt% Al alloy to obtain solidified microstructure ina wide range of cooling rate (5–150 K/s). As-cast microstructural features such as secondary dendrite arm spacing and totalsecond phase fraction were determined as a function of cooling rate. Furthermore, the as-cast samples were solution treatedat 743 K and 793 K for 1, 6, 12 and 24 h to examine the variation of total secondary phases with respect to temperatureand time. The experimental data revealed the dissolution of total secondary phases within 1 h and 12–24 h at 793 K and743 K respectively. Solidification simulations incorporating solute back diffusion, secondary arm coarsening and dendritetip undercooling were performed for accurate analysis of the experimental results. The study also presents a diffusion-basedhomogenization model to investigate the microstructural changes in the ternary alloy during solution treatment. In thismodel, simultaneous dissolution of Mg2Snand Mg17Al12phases along with Sn and Al redistribution in the hcp Mg matrixwas incorporated. The effect of temperature and time was ascertained on the solute distribution and secondary phases dissolution. The modelling results were compared with the homogenized microstructural features.

저녹스 버너 설치 시설의 질소산화물 저감 효율 산정 방법

이기용(Ki Yong Lee),Niladri Talukder 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.12

Seasonal Variability of Marine Fish Diversity in Relation to Water Quality of East Midnapore Coast of West Bengal, India

Chini Deep Sankar,Mondal Niladri,Kar Avijit,Bunholi Ingrid,Singh Sourav,Ghosh Pratik,Patra Prasanta,Patra Shampa,Patra Bidhan Chandra 한국해양과학기술원 2023 Ocean science journal Vol.58 No.2

Marine fishes are one of the important factors in stabilizing the local aquatic ecosystem and regulating the nutritional socioeconomy of local fisher folks. The recent increases in anthropogenic activity, pollution and overfishing have led to the decline of marine fish species richness and their local aquatic habitats. In this study we sought to determine the inter-relationship between water quality, anthropogenic activity, and fish landing stations through a 31 km stretch of the East Midnapore coast in West Bengal, India which is known for its tourist destinations. The study was conducted monthly on different trawler fish landing sites from Dec 2018 to Dec 2021. During this period, we took fish samples and identified them. We obtained water quality data regarding Sea Surface Temperature (SST), Concentration of Chlorophyll-a (Chl-a), Turbidity, and Dissolved Oxygen (DO) in order to identify further correlation between the water quality analysis and species diversity. 154 numbers of commercially important marine fish species were documented. As per the IUCN database, 13% of the total fish species fall under the red list category and 16% of the species reveal a decreasing population trend. The availability of those red-listed fish throughout the season has been shown in the matrix plot to detect their gradual decrease in sighting. After analyzing the water quality data, we found out that DO, SST, Turbidity, and Chl-a correlate with the species richness on some sites and the water parameters are also differs during the seasons. Both fish species richness and water quality have been affected on those fish landing sites which have been subject to heavy anthropogenic loads.