13 research outputs found
High-frequency vertical profiling of meteorological parameters using AMF1 facility during RAWEX-GVAX at ARIES, Nainital
Get PDFAn extensive field study, RAWEX-GVAX, was carried out during a 10-month (June 2011-March 2012) campaign at ARIES, Nainital and observations on a wide range of parameters like physical and optical properties of aerosols, meteorological parameters and boundary layer evolution were made. This work presents results obtained from high-frequency (four launches per day), balloon-borne observations of meteorological parameters (pressure, temperature, relative humidity, wind speed and wind direction). These observations show wind speed as high as 84 m/s near the subtropical jet. It is shown that reanalysis wind speeds are in better agreement at 250 hPa (altitude of subtropical jet) than those above or below this value (100 hPa or 500 hPa). These observations also demonstrate that AIRS-derived temperature profiles are negatively biased in the lower altitude region, whereas they are positively biased near the tropopause. WRF simulated results are able to capture variations in temperature, humidity and wind speed profile reasonable well. WRF and AIRS-derived tropopause height, tropopause pressure and tropopause temperature also show agreement with radiosonde estimates
Heterogeneity in pre-monsoon aerosol types over the Arabian Sea deduced from ship-borne measurements of spectral AODs
No full textShip-borne sunphotometer measurements obtained in the Arabian Sea (AS) in the pre-monsoon season (18 April-10 May 2006) during a cruise campaign (ICARB) have been used to retrieve the Aerosol Optical Depth (AOD; τ) and the Ångström wavelength exponent (α). The continents surrounding the AS produce natural and anthropogenic aerosols that have distinctive influences on α and its spectral distribution. The α values were estimated by means of the least-squares method over the spectral bands 340-1020 nm and 340-870 nm. The spectral distribution of AOD in logarithmic co-ordinates could be fit using a 2nd order polynomial with higher accuracy in the wavelength band 340-1020 nm than in the 340-870 nm band. A polynomial fit analytically parameterizes the observed wavelength dependencies of AOD with least errors in spectral variation of α and yields accurate estimates of the coefficients (α1 and α2). The coarse-mode (positive curvature in the ln λ vs. ln λ) aerosols are mainly depicted in the Northern part of the AS closely associated with the nearby arid areas while fine-mode aerosols are mainly observed over the far and coastal AS regions. In the study period the mean AOD at 500 nm is 0.25±0.11 and the α340-1020 is 0.90±0.19. The α340-870 exhibits similar values (0.92±0.18), while significant differences revealed for the constant terms of the polynomial fit (α1 and α2) proportionally to the wavelength band used for their determination. Observed day-to-day variability in the aerosol load and optical properties are direct consequence of the local winds and air-mass trajectories along with the position of the ship. © Author(s) 2010
Validation of defect association energy on modulating oxygen ionic conductivity in low temperature solid oxide fuel cell
No full textThe defect association modifies the energy barrier for oxygen ion hopping between the vacancies, which is sensitive to the dopant ionic size in the CeO2-δ. Here, the work focuses on the co-dopant strategy of M0.1Sm0.1Ce0.8O2-δ (M = Yb, Gd, Sm, Nd, La) to study the defect association energy, and its subsequent effect on ionic conduction and power density. The electrolyte material with different co-dopants modifies the lattice parameter and bond length of cation–anion, which changes the defect–dopant interactions. Among the tested dopant, Nd0.1Sm0.1Ce0.8O2-δ exhibits the highest ionic conductivity of 34 mS cm−1 at 550 °C, which is nearly 2.3 times higher than the conventional Sm0.2Ce0.8O2-δ. This experimental observation validates the theoretically proposed concept of the balanced defect–dopant interactions at different sites leading to the reduction in defect association enthalpy. The experimental results were rationalized by calculating the defect association enthalpy for the co-doped system using density functional theory via one-cell method. The cell with Nd0.1Sm0.1Ce0.8O2-δ as an electrolyte shows a peak power density of 466 mW cm−2 at 550 °C, which is twice higher than the cell containing standard Sm0.2Ce0.8O2-δ electrolyte (212 mW cm−2). The results confirm that Nd0.1Sm0.1Ce0.8O2-δ is the potential electrolyte for low temperature SOFC operation. (Graphical abstract available) Erratum for Table1: The Publisher regrets that due to a production error Table 1 was incorrect in the above published article. Table 1. The ASR values obtained for button-type cells with various co-doped CeO2-δ electrolytes are also shown. The correct Table 1 is shown at DOI: https://dx.doi.org/10.1016/j.jpowsour.2020.22933
Variations in the cloud-base height over the central Himalayas during GVAX: association with the monsoon rainfall
Get PDFWe present the measurements of cloud-base height variations over Aryabhatta Research Institute of Observational Science, Nainital (79.45 degrees E, 29.37 degrees N, 1958 m amsl) obtained from Vaisala Ceilometer, during the nearly year-long Ganges Valley Aerosol Experiment (GVAX). The cloud-base measurements are analysed in conjunction with collocated measurements of rainfall, to study the possible contributions from different cloud types to the observed monsoonal rainfall during June to September 2011. The summer monsoon of 2011 was a normal monsoon year with total accumulated rainfall of 1035.8 mm during June-September with a maximum during July (367.0 mm) and minimum during September (222.3 mm). The annual mean monsoon rainfall over Nainital is 1440 +/- 430 mm. The total rainfall measured during other months (October 2011-March 2012) was only 9% of that observed during the summer monsoon. The first cloud-base height varied from about 31 m above ground level (AGL) to a maximum of 7.6 km AGL during the summer monsoon period of 2011. It is found that about 70% of the total rain is observed only when the first cloud-base height varies between surface and 2 km AGL, indicating that most of the rainfall at high altitude stations such as Nainital is associated with stratiform low-level clouds. However, about 25% of the total rainfall is being contributed by clouds between 2 and 6 km. The occurrences of high-altitude cumulus clouds are observed to be only 2-4%. This study is an attempt to fill a major gap of measurements over the topographically complex and observationally sparse northern Indian region providing the evaluation data for atmospheric models and therefore, have implications towards the better predictions of monsoon rainfall and the weather components over this region
Doppler Lidar observations over a high altitude mountainous site Manora Peak in the central Himalayan region
No full textThe RAWEX-GVAX field campaign has been carried out from June 2011 to March 2012 over a high altitude site Manora Peak, Nainital (29.4 degrees N; 79.2 degrees E; 1958 m amsl) in the central Himalayas to assess the impacts of absorbing aerosols on atmospheric thermodynamics and clouds. This paper presents the preliminary results of the observations and data analysis of the Doppler Lidar, installed at Nainital. Strong updrafts with vertical winds in the range of similar to 2-4 ms(-1) occurred during the daytime and throughout the season indicating thermally driven convection. On the other hand during nighttime, weak downdrafts persisted during stable conditions. Plan Position Indicator scan of Doppler Lidar showed north-northwesterly winds in the boundary layer. The mixing layer height, derived from the vertical velocity variance, showed diurnal variations, in the range similar to 0.7-1 km above ground level during daytime and very shallow during nighttime
Author Correction: Assessing thermal and economic performance of solar dryers in sustainable strategies for bottle gourd and tomato preservation
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Pharmacokinetic/pharmacodynamic modelling approaches in paediatric infectious diseases and immunology
Get PDFPharmacokinetic/pharmacodynamic (PKPD) modelling is used to describe and quantify dose-concentration-effect relationships. Within paediatric studies in infectious diseases and immunology these methods are often applied to developing guidance on appropriate dosing. In this paper, an introduction to the field of PKPD modelling is given, followed by a review of the PKPD studies that have been undertaken in paediatric infectious diseases and immunology. The main focus is on identifying the methodological approaches used to define the PKPD relationship in these studies. The major findings were that most studies of infectious diseases have developed a PK model and then used simulations to define a dose recommendation based on a pre-defined PD target, which may have been defined in adults or in vitro. For immunological studies much of the modelling has focused on either PK or PD, and since multiple drugs are usually used, delineating the relative contributions of each is challenging. The use of dynamical modelling of in vitro antibacterial studies, and paediatric HIV mechanistic PD models linked with the PK of all drugs, are emerging methods that should enhance PKPD-based recommendations in the future
Aerosol characteristics in north-east India using ARFINET spectral optical depth measurements
No full textFour years (2010–2014) of spectral aerosol optical depth (AOD) data from 4 Indian Space Research Organisation's ARFINET (Aerosol Radiative Forcing over India) stations (Shillong, Agartala, Imphal and Dibrugarh) in the North-Eastern Region (NER) of India (lying between 22–30°N and 89–98°E) are synthesized to evolve a regional aerosol representation, for the first time. Results show that the columnar AOD (an indicator of the column abundance of aerosols) is highest at Agartala (0.80 ± 0.24) in the west and lowest at Imphal (0.59 ± 0.23) in the east in the pre-monsoon season due to intense anthropogenic bio-mass burning in this region aided by long-range transport from the high aerosol laden regions of the Indo-Gangetic Plains (IGP), polluted Bangladesh and Bay of Bengal. In addition to local biogenic aerosols and pollutants emitted from brick kilns, oil/gas fields, household bio-fuel/fossil-fuel, vehicles, industries. Aerosol distribution and climatic impacts show a west to east gradient within the NER. For example, the climatological mean AODs are 0.67 ± 0.26, 0.52 ± 0.14, 0.40 ± 0.17 and 0.41 ± 0.23 respectively in Agartala, Shillong, Imphal and Dibrugarh which are geographically located from west to east within the NER. The average aerosol burden in NER ranks second highest with climatological mean AOD 0.49 ± 0.2 next to the Indo-Gangetic Plains where the climatological mean AOD is 0.64 ± 0.2 followed by the South and South-East Asia region. Elevated aerosol layers are observed over the eastern most stations Dibrugarh and Imphal, while at the western stations the concentrations are high near the surface. The climate implications of aerosols are evaluated in terms of aerosol radiative forcing (ARF) and consequent heating of the atmosphere in the region which follows AOD and exhibit high values in pre-monsoon season at all the locations except in Agartala. The highest ARF in the atmosphere occurs in the pre-monsoon season ranging from 48.6 Wm−2 in Agartala to 25.1 Wm−2 in Imphal. Winter radiative forcing follows that in pre-monsoon season at these locations. The heating rate is high at 1.2 K day−1 and 1.0 K day−1 over Shillong and Dibrugarh respectively in this season. However, Agartala experiences higher surface forcing (−56.5 Wm−2) and consequent larger heating of the atmosphere of 1.6 K day−1 in winter
"Working together" for peace and prosperity of Southeast Asia, 1945-1968: the birth of the ASEAN Way.
Get PDFThe Association of Southeast Asian Nations (ASEAN) is the first organisation of such scope in the region, and one of the oldest in the world. Explaining its longevity are the principles and working methods that have been embodied in the organisation since its inception in 1967. Amongst the most prominent, and least studied, of these has been the so-called ASEAN Way. This thesis traces the troubled origins of ASEAN as an organisation, and the place in it of this paramount principle. It does so by examining its watershed period, defined here as 1945-1968. This is achieved by focussing on the many sources of dissonance and disharmony that had characterised the Southeast Asian region
before ASEAN’s inception, and most strongly so in the Cold War period. Despite this, the thesis suggests, the countries of the region were constantly searching for ways in which some degree of harmonisation, and solid forms of working relations between quite diverse states, could be achieved.
The thesis looks at the historically important staging posts of regional cooperation by examining interactions between countries in ASEAN: the formation process of the Association of Southeast Asia (ASA) and Maphilindo, both of which should be regarded as the forerunners of ASEAN, in addition to the formation of ASEAN itself. In the ASA, the practice of ‘consultation’ was regarded as important to ensure regional cooperation. The practices of ‘face-saving behaviour’ and ‘informality’ were added to these through the subsequent association of Indonesia, Malaya and the Philippines (Maphilindo). Maphilindo also introduced the idea of ‘working together’, this being written in its charter. In the period between the ending of the three-way dispute after the collapse of Maphilindo and the formation of ASEAN, the working method of ‘shelving thorny issues’, on which no compromise could be achieved, emerged. The thesis shows that the latter was first brought into the settlement process of the territorial dispute over Sabah, which was in important respects the catalyst for the formation of ASEAN. The thesis also looks at the settlement
process employed in the so-called Corregidor affair, which occurred only one year after the establishment of ASEAN, and was most important in shaping the working nature of the new association. In the course of the settlement process of the Corregidor affair, ASEAN first exercised in a loosely, and flexibly, integrated way all four of the above-mentioned practices, and did so under the overarching principle of ‘working together’; a notion that in some significant ways defines the ASEAN Way.Thesis (Ph.D.) -- University of Adelaide, School of History and Politics, 201
