Browsing by Author "Mohapatra S.S."

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Affinity propagation clustering for quantification of level of service at uncontrolled median opening
(2014) Mohapatra S.S.; Dey P.P.; Sil G.
Level of service at uncontrolled median openings on multilane divided urban roads is not defined for heterogeneous traffic condition prevailing in India. The LOS of uncontrolled junctions is quantified by the delay experienced by the lower priority movement. Therefore, delay experienced by the lower priority movement i.e. U-turning vehicles at an uncontrolled median opening has been studied to quantify the delay ranges for different LOS categories. Recently developed, affinity propagation (AP) clustering algorithm was employed to achieve the solution of the classification problem. Five validation parameters are analyzed to get the optimal number of cluster number which is crucial for the classification of different level of service categories. Affinity Propagation clustering is used to get the delay ranges for 6 different LOS categories. The range is less than 4 second for best operating condition and is greater than 35 second for the worst operating condition.
Conflicting volume for U-turns at uncontrolled median openings
(2016) Mohapatra S.S.; Dey P.P.; Chandra S.
This paper proposes a practical approach to estimate the conflicting traffic volume caused by U-turns at uncontrolled median openings under mixed traffic conditions. Data were collected at 21 median openings on multi-lane divided roads in India (i.e. 13 on six-lane and eight on four-lane). The road width at the median opening is divided into three parts: zone of severe conflict, zone of safety and unaffected zone based on the placement of the left wheel of U-turning vehicles (left-hand drive rule followed in India). The first two zones together are considered as the conflicting zone for calculating the conflicting traffic. The proportion of opposing through traffic within the conflicting zone is considered as the conflicting traffic volume for U-turns. The conflicting volume at all the sections is estimated based on placement of through traffic across the width of the road and it is found to be dependent on the size of the U-turning vehicle. An equation is suggested to calculate the conflicting traffic based on the composition of U-turning traffic. The conflicting traffic on six-lane roads is found to be relatively, low but on four-lane roads, almost all of the opposing traffic becomes conflicting traffic for U-turns. � 2016, Thomas Telford Services Ltd. All rights reserved.
Estimation of critical gap of U-turns at uncontrolled median openings
(2019) Dash S.; Mohapatra S.S.; Dey P.P.
The estimation of critical gap is an important traffic parameter and this is useful to estimate the capacity of U-turning vehicles at uncontrolled median openings. In this study critical gap is estimated by four different methods by collecting data at seven median openings in India. During field study it was observed that, the heterogeneous traffic in India operates very peculiarly and the rule of priority is often violated and aggressive behavior of the minor stream vehicles compels the major stream vehicles to slow down to provide sufficient gap for the U-turn maneuver. These peculiar characteristics warrant for a re-look into the methodology of critical gap estimation. An unconventional method of critical gap estimation using the merging time of the U-turning vehicle is proposed. The merging time to clear the conflict area at uncontrolled median opening was calculated from field data and this time is utilized to estimate the critical gap for different categories of vehicle. � 2017, � 2017 Informa UK Limited, trading as Taylor & Francis Group.
Estimation of U-turn capacity at median opening
(2018) Mohapatra S.S.; Dey P.P.
Median openings are provided in multilane divided roads to enable U-turns. The atypical conditions prevailing in India motivated this study for the development of a methodology for the proper computation of the capacity for U-turns at these locations. Harders' formula has been widely used by various researchers to evaluate capacity for U-turns and this formula needs three elementary factors-namely, conflicting traffic volume, critical gap, and follow-up time. We collected the required data for capacity estimation from different uncontrolled median openings in India. We estimated the first input parameter required for Harders' formula, conflicting traffic volume, by analyzing the lateral placement of vehicles at the median opening area. We estimated the second parameter, critical gap, by using four different critical gap estimation procedures-namely; modified Raff, maximum likelihood, macroscopic probability equilibrium, and merging behavior. The third parameter, follow-up time, was measured directly in the field. Consequently, we calculated U-turn capacity for the given traffic streams and the findings were tested against the field capacity estimated in the field using Kyte's method. We then determined a suitable method for critical gap estimation in the Indian context by using two statistical parameters. � 2018 American Society of Civil Engineers.
Heterobimetallic Ir-Sn catalysis: Aza-Friedel-Crafts reaction of N-sulfonyl aldimines
(2013) Chatterjee P.N.; Maity A.K.; Mohapatra S.S.; Roy S.
The heterobimetallic complex [Ir(COD)(SnCl3)Cl(?-Cl)] 2 catalyzes the aza-Friedel-Crafts reaction of 1,3,5- trimethoxybenzene, as well as substituted indoles with N-sulfonyl aldimines leading to the formation of diarylamines and triarylmethanes in good yields. The symmetrical triarylmethanes were also obtained from diarylamines and suitable nucleophiles via simultaneous cleavage of sp3 C-N bond and elimination of 1,3,5-trimethoxybenzene.
Lateral placement of U-turns at median openings on six-lane divided urban roads
(2015) Mohapatra S.S.; Dey P.P.
Study on lateral placement of U-turning vehicle is carried out by collecting data at 13 different median openings of six-lane divided roads. It was found that the lateral placement of all the vehicles'' taking U-turn at median opening may be unimodal or bimodal. The unimodal distribution was described by normal distribution, whereas bimodal distribution was described separately by two different normal distributions; one for only 2-W'' and other for all the vehicles excluding 2-W.'' Equations were developed and parameters were calculated to describe a bimodal placement distribution curve. The issue of bimodality in placement was investigated statistically and the separation factor (S(r)) and placement factor (PF) were used to describe the issue. This study on the lateral placement of Uturning vehicles holds significance in the better estimation of conflicting traffic volume, which is essential for the correct estimation of the capacity of U-turns at median openings in mixed traffic condition. � 2015 Institute of Materials, Minerals and Mining.
Mercury based drug in ancient India: The red sulfide of mercury in nanoscale
(2017) Mukhi P.; Mohapatra S.S.; Bhattacharjee M.; Ray K.K.; Muraleedharan T.S.; Arun A.; Sathyavathi R.; Juluri R.R.; Satyam P.V.; Panda A.K.; Biswas A.; Nayak S.; Bojja S.; Pratihar S.; Roy S.
Mercury is one of the elements which had attracted the attention of the chemists and physicians of ancient India and China. Among the various metal based drugs which utilize mercury, we became interested in the red sulfide of mercury which is known in ancient Indian literature as rasasindur (alias rasasindura, rasasindoor, rasasinduram, sindur, or sindoor) and is used extensively in various ailments and diseases. Following various physico-chemical characterizations it is concluded that rasasindur is chemically pure ?-HgS with Hg:S ratio as 1:1. Analysis of rasasindur vide Transmission Electron Microscopy (TEM) showed that the particles are in nanoscale. Bio-chemical studies of rasasindur were also demonstrated. It interacts with Bovine Serum Albumin (BSA) with an association constant of (9.76 � 0.56) � 103 M?1 and behaves as a protease inhibitor by inhibiting the proteolysis of BSA by trypsin. It also showed mild antioxidant properties. � 2017 Transdisciplinary University, Bangalore and World Ayurveda Foundation
Merging process of u-turns at uncontrolled median openings under mixed traffic conditions
(2018) Sil G.; Mohapatra S.S.; Dey P.P.; Chandra S.
At an uncontrolled median opening, the limited priority situation and the high degree of heterogeneity in traffic stream make the merging manoeuvre of U-turning vehicles very much complex. This study is an attempt to understand this merging manoeuvre. The different types of merging manoeuvres have been identified in the field and accordingly classified into different categories. Depending upon the number of vehicles that can merge all together into the opposing through traffic by accepting a single gap, the merging has been classified into two types: single entry merging and multiple entry merging. On the other hand, based on the situation of priority of movement, the merging process is divided into another two categories: ideal merging and forced merging. More explicitly, the ideal merging is split into free merging and Swift Merging (SM). In addition, the forced entry merging is categorized into Gradual Merging (GM) and Aggressive Merging (AM). Time distance diagrams for different types of merging are presented for their better understanding. Field data collected at seven median openings located on various 6-lane divided urban roads are used to analyse different types of merging in a mixed traffic situation. All vehicles plying on the road are divided into 5 categories such as car, motorized two-wheeler (2-W), motorized three-wheeler (3-W), Sports Utility Vehicle (SUV), and Light Commercial Vehicle (LCV) and the merging behaviour of these categories of vehicles have been studied. The effect of influencing parameters like opposing traffic volume and delay on merging are investigated. Mathematical relations are developed between Merging Time (MT) of a vehicle type and the opposing traffic volume. To address the effect of Service Delay (SD) on the MT of a vehicle, models are proposed between SD and MT for all the five categories of vehicles. The two types of merging; gradual and swift are prominently observed in field. The time required by different categories of vehicles for these two merging at various traffic volume levels are determined. Finally, two-tailed t-test is conducted to see if the MT for the two different types of merging is statistically different. � 2016 Vilnius Gediminas Technical University (VGTU) Press.
Modeling the critical position of U-turning vehicles at uncontrolled median openings
(2016) Mohapatra S.S.; Dey P.P.; Chandra S.
The present study provides a methodology for identification of the conflict zone between a turning vehicle and on-coming vehicles at uncontrolled median openings on urban roads under mixed traffic conditions. Data for turning movements of different types of vehicles were collected at 13 median openings on 6-lane roads and 8 median openings on 4-lane roads in different cities of India. These data are analyzed statistically and it was found that the critical position (path of the outer wheel) of a vehicle is influenced by the vehicle size and the road width. In the case of 6-lane roads, the critical position of turning vehicle may follow a unimodal or bimodal distribution depending upon the proportion of motorized two-wheelers (2-W) in the turning volume. On 4-lane roads, the gamma distribution was found to fit the placement data at all the eight sections. A simple model is proposed to identify the boundary of the conflict zone at median openings. The geometrical augmentation required at the median opening in order to avoid the conflict between turning vehicles and through traffic in the opposing median lane is also suggested. � 2015, Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.
Palladium(II) in electrophilic activation of aldehydes and enones: Efficient C-3 functionalization of indoles
(2015) Mohapatra S.S.; Mukhi P.; Mohanty A.; Pal S.; Sahoo A.O.; Das D.; Roy S.
The regioselective C-3 alkylation of indoles with aldehydes and enones as electrophiles is catalyzed by a d8 late transition metal complex PdCl2(MeCN)2 at room temperature in the presence of air/moisture and in the absence of any additional acid/base, additive, or ligand. The active catalyst in this alkylation is an organometallic intermediate C1 which is formed from the reaction of indole with the palladium(II) pre-catalyst. The crystallographic characterization and reactivity of C1 and its analogs with indoles and surrogates is in progress. � 2015 Elsevier Ltd. All rights reserved.
Recent advances in heterobimetallic catalysis across a "transition metal-tin" motif
(2015) Das D.; Mohapatra S.S.; Roy S.
Heterobimetallic catalysts, bearing a metal-metal bond between a transition metal (TM) and a tin atom, are very promising due to their ability in mediating a wide variety of organic transformations. Indeed the utilization of such catalysts is a challenging and evolving area in the field of homogeneous catalysis. Catalysis across a 'TM-Sn' motif is an emerging area in the broader domain of multimetallic catalysis. The present review apprises the chemists' community of the past, present and future scope of this versatile catalytic motif. The TM-Sn catalyzed reactions presented include, among others, Friedel-Crafts alkylation, carbonylation, polymerization, cyclization, olefin metathesis, Heck coupling, hydroarylation Michael addition and tandem coupling. The mechanistic aspects of the reactions have been highlighted as well. � The Royal Society of Chemistry 2015.
Service delay and merging time evaluation at median openings
(2019) Sil G.; Mohapatra S.S.; Dey P.P.; Chandra S.
Studies have been carried out on delays at unsignalized intersections but there is hardly any report is available on delays at unsignalised median openings on multi-lane divided urban roads. The present study estimates the average service delay to vehicles and proposes service delay models based on microscopic analysis of delay data under highly heterogeneous and unruly traffic conditions. The data for the study were collected by video recording at seven different uncontrolled median openings on multi-lane divided urban roads in India. The conflicting traffic was measured as the exact number of conflicting vehicles (n) as seen by a particular U-turning vehicle. The number of conflicting vehicles and the opposing through traffic were found to affect the service delay and mathematical models have been proposed. The merging time was also estimated for different categories of vehicles. Furthermore, the effect of opposing traffic volume and delay on merging time is studied. � 2019 Institute for Transport Studies in the European Economic Integration. All rights reserved.
Utilization of flow chemistry in catalysis: New avenues for the selective synthesis of Bis(indolyl)methanes
(2017) Mohapatra S.S.; Wilson Z.E.; Roy S.; Ley S.V.
Flow chemistry enables the preparation of bis(indolyl)methanes from various indoles and structurally divergent aldehydes using Sc(OTf)3 catalysis. The reaction is regioselective for C-3 functionalization of the indoles, occurring over short reaction times allowing for rapid investigation of scope with straightforward work up facilitating product isolation. � 2017 The Authors