Showing papers by "Prashant Kumar published in 2013"

Can a “Blue Sky” return to Indian megacities?

Abstract: Deterioration of air quality in Indian megacities (Delhi, Mumbai or Kolkata) is much more significant than that observed in the megacities of developed countries. Densely packed high-rise buildings restrict the self-cleaning capabilities of Indian megacities. Also, the ever growing number of on-road vehicles, resuspension of the dust, and anthropogenic activities exacerbate the levels of ambient air pollution, which is in turn breathed by urban dwellers. Pollution levels exceeding the standards on a regular basis often result in a notable increase in morbidity and mortality. This article discusses the challenges faced by Indian megacities in their quest for sustainable growth, without compromising the air quality and urban way of life.

Indoor-outdoor concentrations of particulate matter in nine microenvironments of a mix-use commercial building in megacity Delhi

Abstract: Three naturally and six mechanically ventilated microenvironments (MEs) of a mix-use commercial building in Delhi are used to study indoor–outdoor (I/O) relationships of particulate matter ≤10 μm (PM10), ≤2.5 μm (PM2.5), and ≤1 μm (PM1). Effect of environmental and occupancy parameters on the concentrations of PM during working and non-working hours (i.e., activity and non-activity periods, respectively) are also investigated. Average outdoor concentration of PM10 and PM2.5 were found to exceed the 24-h averaged national standard values, showing a polluted environment surrounding the studied building. During working hours, indoor PM10 concentration was found 6–10 times, both PM2.5 and PM1 were 1.5–2 times, higher than the non-working hours in the selected MEs. The variations of indoor concentrations were highest (17.1–601.2 μg/m3) for PM10 compared with PM2.5 (16.9–102.6 μg/m3) and PM1.0 (10.6–63.6 μg/m3). The I/O for PM10, PM2.5, and PM1.0 varied from 0.37–3.1, 0.2–3.2, and 0.17–2.9, respectively. The results suggest highest I/O for PM10, PM2.5, and PM1 as 3.1, 2.15, and 1.76, respectively, in all the three natural-ventilated MEs (canteen, kitchen, reception). Irrespective of PM types, the average I/O was 1 for naturally ventilated MEs. As opposed to PM1, better correlation (r > 0.6) was noted between indoor PM10, PM2.5, and CO2 concentrations in most of the airtight MEs.

Energy-pollution nexus for urban buildings.

Abstract: Since the first oil crisis in 1974, economic reasons placed energy saving among the top priorities in most industrialised countries. In the decades that followed, another, equally strong driver for energy saving emerged: climate change caused by anthropogenic emissions, a large fraction of which result from energy generation. Intrinsically linked to energy consumption and its related emissions is another problem: indoor air quality. City dwellers in industrialised nations spend over 90% of their time indoors and exposure to indoor pollutants contributes to ~2.6% of global burden of disease and nearly 2 million premature deaths per year1. Changing climate conditions, together with human expectations of comfortable thermal conditions, elevates building energy requirements for heating, cooling, lighting and the use of other electrical equipment. We believe that these changes elicit a need to understand the nexus between energy consumption and its consequent impact on indoor air quality in urban buildings. In our opinion the key questions are how energy consumption is distributed between different building services, and how the resulting pollution affects indoor air quality. The energy-pollution nexus has clearly been identified in qualitative terms; however the quantification of such a nexus to derive emissions or concentrations per unit energy consumption is still weak, inconclusive and requires forward thinking. Of course, various aspects of energy consumption and indoor air quality have been studied in detail separately, but in-depth, integrated studies of the energy-pollution nexus are hard to come by. We argue that such studies could be instrumental in providing sustainable solutions to maintain the trade-off between the energy efficiency of buildings and acceptable levels of air pollution for healthy living.

Influence of virtual changes in building configurations of a real street canyon on the dispersion of PM10

Abstract: Four geometrical configurations of a real street canyon in Barreiro city (Portugal) are considered to study their influence on the dispersion of PM. These configurations include actual architectural layout of the street (Option 1), and three virtual cases (Options 1-3). Option 2 includes the modification of real geometry by including 4 m gaps between the buildings situated on the southern part of the street canyon. Option 3 considers 6 m gaps between buildings as opposed to 4 m gaps in Option 2. Option 4 assumes the same height for all buildings on the southern part of the street canyon, with no gaps between buildings. Computational fluid dynamics code (CFD), FLUENT, is used to simulate the detailed flow and turbulence characteristics in three-dimensional domain of chosen street canyon, together with the PM dispersion for both the summer and winter seasons. The modelled PM concentrations were then compared with the measured data at seven different locations in the street canyon. Our results indicate up to 23% lower PM concentrations at 1.5 m above the road level during the along-canyon wind direction due to the channelling of flow, compared with those observed during the cross-canyon wind direction. Detailed inspection of the results obtained from the Options 1-3 indicated that the spacing between the buildings tend to increase particle dilution during the cross-canyon winds, resulting in up to 20, and 22% reduced concentrations for options 2, and 3 respectively, compared with the actual configuration (Option 1). The largest improvement (∼7%) in the PM concentrations was given by Option 2, while other options showed modest changes. Possible reasons for these changes under varying meteorological conditions are explained in the context of changing building configurations and their implications in city planning. © 2013 Elsevier Ltd. All rights reserved.

Performance Analysis of ZRP over AODV, DSR and DYMO for MANET under Various Network Conditions using QualNet Simulator

Abstract: A network which does not require any fixed pre-existing infrastructure and can be defined as a set of mobile nodes is called MANET. In MANET mobile nodes are communicating through wireless medium. In MANET all mobile nodes behaves as router and when required they takes part in discovery and maintenance of the route to the other node. One of the major challenges in designing a routing protocol for the MANET is to determine a packet route; a node needs to know at least about its neighbors. On the other hand in MANET wireless networks conditions changes frequently with time due to the mobile nodes thus routing becomes a challenging task. To serve this purposes various proactive, reactive and hybrid routing protocols are developed by researchers. Among all AODV, DSR, DYMO and ZRP are well known popular routing protocols and have been standardized by the IETF MANET WG. ZRP is a well known hybrid routing protocol. To understand its suitability we must understand its behavior under various real time conditions. This paper presents performance analysis of ZRP routing protocol over AODV, DSR, and DYMO routing protocols using QualNet version 5.2. This experiment uses different network conditions, close to real time condition, for the performance analysis of ZRP using AODV, DSR and DYMO as a reference protocol. Simulations are carried out to analyze the different network parameters such as throughput, average jitter, average end-toend delay and packet delivery ratio.

Enlightening and Noxious Shades of Nanotechnology Application in Concrete

Abstract: Nanotechnology is currently a key area of research with both useful applications and environmental concerns. The aim of this chapter is to evaluate both the positive and negative aspects of applying nanotechnology within concrete materials and structures. The chapter begins with information on current applications of nanotechnology enabled products within the construction industry, followed by a summary of recent research and review articles related to the application of nanomaterials in concrete technology. The broader application of nanotechnology integrated products in the construction industry for the creation of lighter and stronger structural composites, low maintenance surface coatings, and enhancing the properties of cementitious materials are considered. The application of nanosensors in the construction industry is also discussed. The subsequent sections present an overview of the potential environmental impacts of nanotechnologies in terms of the release of particulate pollutants, including nanoparticles, during the construction, demolition and refurbishment activities. The chapter finally concludes by highlighting some areas for future work.

H15-3: Number concentration, distribution and transformation of nanoparticles in and outside a car cabin

Abstract: City dwellers are regularly exposed to nanoparticle (i.e. particles < 300 nm in diameter), emitted by fossil fuelled vehicles, whilst commuting by transport modes such as taxis and buses. Exposure to these nanoparticles can lead to significant adverse effects on human health. This study aims to investigate spatial distribution of particle number concentrations (PNCs) and distributions (PNDs) in and outside a car cabin during driving. Possible influences of particle transformation processes on PNC and PNDs in the car cabin are also investigated. Another objective is to predict the PNCs in the car cabin using those measured outside. Measurements of particles in the 5-560 nm size range were conducted using a fast response differential mobility spectrometer (DMS50) in conjunction with an automated switching system. The DMS50 was used to measure size-resolved sequential distributions at: (i) four seats in the car cabin during about 700 minutes of driving, and (ii) two points at the driver's seat, inside and the front bonnet outside the cabin, during about 500 minutes of driving. The emission penetration and spatial distribution in the car cabin through (i) the ventilation system (Vent), and (ii) door/window sealing (CG) was simulated by means of three-dimensional computational fluid dynamics (CFD) using the Fluent code. Standard k-e turbulence model was employed to simulate turbulence flow in the cabin. Vent/CG emission ratio was altered for the two different scenarios (0.9/0.1 and 0.7/0.3), indicating; (i) no filter fitted Vent and high vehicle sealing efficiency, (ii) filter fitted Vent and reduced sealing efficiency. Four-point measurements indicated that the average PNCs at the front seats (3.96 and 3.85 × 104 cm-3) were almost identical to those found at the rear seats (3.82 and 4.00 × 104 cm-3). The very small differences (∼0.1%) suggest that the car cabin is very close to a well-mixed microenvironment. Two-point measurements revealed that the ratio of average PNCs in (2.72 ± 1.03 × 104 cm-3) and outside the car cabin (3.75 ± 1.62 × 104 cm-3) was about 0.72. A semi-empirical box mode model was introduced to predict PNCs in the car cabin as a function of those measured outside and cabin air exchange rate. Performance evaluation of the box model against statistical measures was within the recommended guidelines for urban air quality modelling. Overall, PNCs calculated by the model demonstrate a satisfactory correlation with the measured values. CFD simulations indicate that away from the Vent, emission is dispersed almost uniformly in the car cabin. Vent / CG ratios indicated that despite changes of emission filtering into the cabin, the dispersion characteristics remained almost identical at passengers' breathing height (i.e. 1.2 m from the floor).

H15-181: Influence of roadside vegetation barriers on concentrations of traffic-spewed ultrafine particles

Abstract: The study of ultrafine particles (those below 100 nm in diameter) is of great interest to the scientific community and policy makers due to their likely impacts on human health and the environment. Understanding the behaviour of ultrafine particles from their number concentrations and size distribution point of view in the ambient air will help to expedite the development of regulatory controls. Vegetation barriers are used in many places to reduce the pollution generated by the road traffic from reaching to the people living in urban areas, especially close to the road, where the ultrafine particles are expected to be in high concentrations. Limited information currently exist that could reveal detailed understanding about the effectiveness of near road vegetation barriers in removing concentrations of ultrafine particles. A fast response differential mobility spectrometer (DMS50) is used for the pseudo-simultaneous measurements of number and size distributions in the 5-560 nm size range. The measurements were made at four different points along the side of a busy highway. These points were at the front, middle and back of the vegetation barrier, and at a point without any vegetation; all these points were at the same height above the road level. The data was collected at 10 Hz sampling rate, with T 10-90% equal to 500 milliseconds, during a weekday (7 August 2012) and a weekend (11 August 2012). Analysis of the data was performed to investigate the influence of near road vegetative barriers on the number concentration and size distributions. Further analysis will be carried out to develop understanding about the effect of wind direction on the efficiency of the vegetation barrier and an indication about the dispersion of particles as they move away from source (vehicle tailpipe) through the vegetation barriers to roadside footpath. Preliminary results based on the weekday data shows that the concentrations of particles gradually decrease while passing through the vegetation barrier. No clear trend was found from the weekend data due to winds being parallel to road and low traffic density. Detailed analysis of the data is currently underway.