Civil Engineering

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Shiv Nadar University

Pedestrian fatalities from 2001 to 2009 in Delhi, India show that pedestrians have the largest share in total road fatalities. Though, facilities like pedestrian underpasses and overpasses are provided to cross the road at several locations, all too often pedestrians do not use them. This study was designed to analyze the pedestrians’ perceptions for underutilization of pedestrian facilities. Five hundred pedestrians were interviewed at seven different locations based on available pedestrian facilities such as zebra crossing, pedestrian underpasses and overpasses. Analysis of usage of these facilities showed that usage of underpasses and zebra crossing is less by female respondents. To know the safety and convenience perception of pedestrians with respect to a specific facility, ordinal logit model was used in this study. Results showed that convenience perception is statistically significant (at 95% CI) for the use of zebra crossings. The conclusions drawn from this study can be used to improve the state of pedestrian facilities in Delhi for prioritization of the facilities based on stated preferences. © 2016 Elsevier Ltd

(SoE) School of Engineering

World University root node

Transportation Research Part F: Traffic Psychology and Behaviour

Pedestrians perceptions for utilization of pedestrian facilities – Delhi, India

Traffic crash fatalities from 2006 to 09 in Delhi, India show that pedestrians have the largest share in total road fatalities. Perception of risk provides important information to identify potential crash risk. Thus, the main objective of this paper is to explore the pedestrian perception of risk in getting involved in a traffic crash in different locations and the role of built environment features in risk perception of pedestrians. Locations having a high number of pedestrian fatal crashes were identified using GIS map of Delhi. Pedestrian perceptions of risk at forty-five actual crash sites were collected through questionnaire survey. Risk perception of pedestrians of built environment features were analyzed based on pedestrian demographic characteristics. Ordered logit model was used to examine the influence of these variables on risk perception of respondent's neighborhood and of the location where the survey was conducted. Seventy percent respondents perceive the neighborhoods where they reside having higher risk than the actual crash locations. Several factors such as gender, number of lanes, sidewalk width, sidewalk maintenance, traffic speed and traffic volume were significantly associated with perceived risk. Survey sites were further categorized into four groups i.e. foot of flyover, four-way junctions below flyover, midblocks and intersections to find the impact of characteristics of locations on pedestrians' risk perception of different locations. Four-way junctions below flyover were found to have higher perceived risk compared to other locations. © 2016 Elsevier Ltd.

Safety Science

Pedestrians risk perception of traffic crash and built environment features - Delhi, India

In order to meet stringent environmental, safety and performance requirements from respective regulatory bodies, various technology-based industries are promoting the use of advanced carbon nanotube (CNT) reinforced lightweight and high strength polymer nanocomposites (PNCs) as a substitute to conventional materials both in structural and non-structural applications. The superior mechanical properties of PNCs made up of CNTs or bundles of CNTs can be attributed to the interfacial interaction between the CNTs and matrix, CNT's morphologies and to their uniform dispersion in the matrix. In PNCs, CNTs physically bond with polymeric matrix at a level where the assumption of continuum level interactions is not applicable. Modeling and prediction of mechanical response and failure behavior of CNTs and their composites becomes a complex task and is dealt with the help of up-scale modeling strategies involving multiple spatial and temporal scales in hierarchical or concurrent manner. Firstly, the article offers an insight into various modeling techniques in studying the mechanical response of CNTs; namely, equivalent continuum approach, quasi-continuum approach and molecular dynamics (MD) simulation. In the subsequent steps, these approaches are combined with analytical and numerical micromechanics models in a multiscale framework to predict the average macroscopic response of PNCs. The review also discusses the implementation aspects of these computational approaches, their current status and associated challenges with a future outlook.

Progress in Aerospace Sciences

Modeling of carbon nanotubes and carbon nanotube-polymer composites

Gaseous toxic air pollutants are normally associated with acute short-term and chronic long-term health effects, and hence measurement of these pollutants is essential on a daily basis to understand the science of their occurrences. In this study, gaseous O3, SO2, NO2, NH3, HNO2, HNO3, and HCl and water-soluble inorganic ions (Na+, K+, Ca2+, Mg2+, NH4 +, NO3 -, SO4 2-, and Cl-) in PM2.5 were measured during a summer in Kanpur, India, using an annular denuder technique on a time resolution of 12 h. The denuder technique revealed that evaporation losses of NH4 +, Cl-, and NO3 - from a Teflon filter and trapped in nylon filters were temperature sensitive. The evaporation losses were 17.8 ± 8.7%, 29.5 ± 19.3%, and 37.1 ± 25.9% during daytime, and 10.2 ± 6.4%, 17.7 ± 10.1%, and 19.3 ± 12.2% during nighttime for NH4 +, Cl-, and NO3 -, respectively. Overall, 24 h average concentrations of O3, SO2, NO2, NH3, HNO2, HNO3, and HCl were 49.6, 8.6, 34.2, 21.5, 3.6, 9.8, and 1.4 μgm-3, respectively; and 2.1, 1.5, 2.9, 1.1, 13.1, 12.9, 19.7, and 1.3 μgm-3 were observed for Na+, K+, Ca2+, Mg2+, NH4 +, NO3 -, SO4 2-, and Cl-, respectively, in PM2.5. Levels of O3, NH3, HNO2, HNO3, PM2.5, K+, Ca2+, Mg2+, NO3 -, and SO4 2- showed significant diurnal variations at 95% confidence level. However, SO2, NO2, HCl, Na+, NH4 +, and Cl- did not show any significant diurnal variations. Ion balance showed that an abundant quantity of NH3 was present in the study area to neutralize H2SO4, HNO3, and HCl to form (NH4)2SO4, NH4NO3, and NH4Cl, and thermodynamics for the formation of NH4NO3 was favored under more humid conditions. © 2015 American Society of Civil Engineers.

Journal of Hazardous, Toxic, and Radioactive Waste

Characterization of gaseous pollutants and water-soluble inorganic ions in PM2.5 during Summer time at an urban site of North India

Rotating biological contactors (RBCs) are low-cost, efficient and an eco-friendly volatile organics control technique. In this study, a state-of-art disk-based RBC has been modified to a drum-based with sponge supporting medium and its performance at different inlet loading rates (ILR) of gaseous benzene, and its effect on elimination capacity (EC) and removal efficiency (RE) have been investigated. The results showed that the RE remained over 90% up to the ILR of about 8 g m-3 h-1, and decreased to about 80% with the further increase in ILR. The EC reached maximum to about 45 g m-3 h-1 at a benzene load of about 69 g m-3 h-1. The EC of benzene increased with the increase in loading rate, but the RE showed an opposite trend. The production of carbon dioxide, which determines the degree of pollutant degradability, also increased with the increase in EC. Along with benzene the nutrients (NH3-N and PO4-P) from liquid phase also got removed in RBC, which shows its potential application in industries. Furthermore, a potential benzene degrader was tentatively identified as genera Enterobacter. The maximum biodegradation rate (rmax) and half saturation constant (Ks) were determined as 21.46 g m-3 h-1 and 1.71 g m-3, respectively. © 2016 Elsevier Ltd.

International Biodeterioration and Biodegradation

Benzene control from waste gas streams with a sponge-medium based rotating biological contactor

Epoxy matrix reinforced with conventional microscale short carbon fibers (SCFs) and carbon nanotubes (CNTs) form a hybrid material system where the characteristic length scales of SCFs and CNTs differ by multiple orders of magnitude. Several recent studies show that the addition of CNTs into a non-conducting polymer matrix improves both structural performance such as modulus, strength and fracture toughness and functional response such as electrical and thermal conductivities of the resulting nano-composite. In this study, a physics-based hierarchical multiscale modeling approach is presented to calculate the effective electrical conductivity of SCF-CNT-polymer hybrid composites. A dual step procedure is adopted to couple the effects of nano- and micro-scale so as to estimate the effective electrical properties of the composite. First, CNTs are dispersed into the non-conducting polymer matrix to obtain an electrically conductive CNT-epoxy composite. The effective electrical conductivity of CNT-epoxy composite is modeled using a physics-based formulation for both randomly distributed and vertically aligned cases of CNTs and the results are verified with the measured data available in the literature. In the second step, SCFs are randomly distributed in the CNT-epoxy composite and the effective electrical conductivity of the resulting SCF-CNT-epoxy hybrid composite is estimated using a micromechanics based self-consistent approach considering SCFs as microscopic inhomogeneities.

Materials and Design

Multiscale modeling of effective electrical conductivity of short carbon fiber-carbon nanotube-polymer matrix hybrid composites

Design of high-performance power lines with advanced materials is indispensable to effectively eliminate losses in electrical power transmission and distribution (T&D) lines. In this study, aluminum conductor composite core with carbon nanostructure (ACCC-CNS) coating in a multilayered architecture is considered as a novel design alternative to conventional aluminum conductor steel-reinforced (ACSR) transmission line. In the multiphysics approach presented herein, first, electrothermal finite element analysis (FEA) of the ACSR line is performed to obtain its steady-state temperature for a given current. Subsequently, the sag of the ACSR line due to self-weight and thermal expansion is determined by performing thermostructural analysis employing an analytical model. The results are then verified with those obtained from the FEA of the ACSR line. The electrothermal finite element (FE) model and the thermostructural analytical model are then extended to the ACCC-CNS line. The results indicate that the ACCC-CNS line has higher current-carrying capacity (CCC) and lower sag compared to those of the ACSR line. Motivated by the improved performance of the ACCC-CNS line, a systematic parametric study is conducted in order to determine the optimum ampacity, core diameter and span length. The findings of this study would provide insights into the optimal design of high-performance overhead power lines.

Journal of Engineering Materials and Technology, Transactions of the ASME

High-Ampacity Overhead Power Lines with Carbon Nanostructure-Epoxy Composites

Atmospheric particulate mercury (PHg) is recognized as a global pollutant that requires regulation because of its significant impacts on both human health and wildlife. The haze episodes that occur frequently in China could influence the transport and fate of PHg. To examine the characteristics of PHg during haze and non-haze days, size-fractioned particles were collected using thirteen-stage Nano-MOUDI samplers (10 nm-18 μm) during a severe haze episode (from December 2013 to January 2014) in Shanghai. The PHg concentration on haze days (4.11 ± 0.53 ng m-3) was three times higher than on non-haze days (1.34 ± 0.15 ng m-3). The ratio of the PHg concentration to total gaseous mercury (TGM) ranged from 0.42 during haze days to 0.21 during non-haze days, which was possibly due to the elevated concentration of particles for gaseous elemental mercury (GEM) adsorption, elevated sulfate and nitrate contributing to GEM oxidation, and the catalytic effect of elevated water-soluble inorganic metal ions. PHg/PM10 during haze days (0.019 ± 0.004 ng/μg) was lower than during non-haze days (0.024 ± 0.002 ng/μg), and PHg/PM10 was significantly reduced with an increasing concentration of PM10, which implied a relatively lower growth velocity of mercury than other compositions on particles during haze days, especially in the diameter range of 0.018-0.032 μm.During haze days, each size-fractioned PHg concentration was higher than the corresponding fraction on non-haze days, and the dominant particle size was in the accumulation mode, with constant accumulation to a particle size of 0.56-1.0 μm. The mass size distribution of PHg was bimodal with peaks at 0.32-0.56 μm and 3.1-6.2 μm on non-haze days, and 0.56-1.0 μm and 3.1-6.2 μm on haze days. There was a clear trend that the dominant size for PHg in the fine modes shifted from 0.32-0.56 μm during non-haze days to 0.56-1.0 μm on haze days, which revealed the higher growth velocity of PHg on haze days due to the condensation and accumulation of Hg in particles. Traffic emissions and coal combustion may contribute to the high concentrations of Hg, because PHg of every size was found to correlate positively with SO2, NO2, and CO. A correlation was found between every mode of PHg and relative humidity, which affected the gas-particle partitioning of semi-volatile organic compounds, resulting in effective partitioning into aerosols. The strong correlations between Hg and water-soluble ions implied the oxidation of elemental Hg was the main gas-to-particle chemical transformation process. © 2016 Elsevier Ltd.

Atmospheric Environment

Characteristics of atmospheric particulate mercury in size-fractionated particles during haze days in Shanghai

This paper presents a case for extension of structural health monitoring (SHM) technologies to offer solutions for biomedical problems. SHM research has made remarkable progreß during the last two/ three decades. These technologies are now being extended for poßible applications in the bio-medical field. Especially, smart materials, such as piezo-electric ceramic (PZT) patches and fibre-Bragg grating (FBG) sensors, offer a new set of poßibilities to the bio-medical community to augment their conventional set of sensors, tools and equipment. The paper presents some of the recent extensions of SHM, such as condition monitoring of bones, monitoring of dental implant post surgery and foot preßure measurement. Latest developments, such as non-bonded configuration of PZT patches for monitoring bones and poßible applications in osteoporosis detection, are also discußed. In eßence, there is a whole new gamut of new poßibilities for SHM technologies making their foray into the bio-medical sector. © 2015 SPIE.