Assessment of digital image classification algorithms for forest and land-use classification in the eastern Himalayas using the IRS LISS III sensor

The article describes the assessment and discusses the potential of different methods of classifying Linear Imaging Self-Scanning Sensor (LISS) III sensor data for vegetation-cover type and land-use mapping in the hilly terrain of the eastern Arunachal Pradesh, in the northeastern part of India. The forest cover types and their distribution in the study area are governed by climatic conditions and topographical features, which change along the gradient from tropical in the south to alpine in the Greater Himalayas in the north. Arunachal Pradesh is part of the Himalayan Biodiversity Hotspot and is at the tri-junction of Indian, Sino-Japanese, and Indo-Malayan floristic regions. The evergreen forests in the area represent climatic climaxes, which are partly original virgin and partly affected by anthropogenic pressures. Due to phenological and physiognomic similarities in ecotone regions, the differences in the spectral reflectance between adjacent forest types are not well pronounced. The age of the forests, terrain characteristics, and the nature of the vegetation itself could be other reasons for the near-similar reflectance. It is for these reasons that conventional classification algorithms for supervised and unsupervised classification do not perform well. Therefore, there is a need to find a suitable method for vegetation and land-use mapping with high mapping accuracy in this region, which is a biodiversity hotspot. A suitable classification technique is important to characterize vegetation-cover type in this complex terrain. We tested unsupervised, supervised, hybrid, object-oriented, and expert classification techniques for vegetation and land-use mapping on Indian Remote Sensing (IRS)-1C LISS III data. The expert classifier produced the highest accuracy (93.39%) followed by object-oriented, hybrid, and supervised and unsupervised classification techniques.     

Annual and seasonal variations in tropospheric ozone concentrations around Varanasi

This study examines the annual, seasonal and diurnal variations in the ambient concentrations of ozone at a suburban site of Varanasi, India, during 2002–2006. Prominent seasonal variations in ozone concentrations were recorded. Ozone concentrations were higher during the warmer months. Daytime 12‐hourly mean monthly ozone concentrations varied from 45.18 to 62.35 ppb during summer, from 28.55 to 44.25 ppb during winter and from 24 to 43.85 ppb during the rainy season from 2002 to 2006. Distinct diurnal variations in ozone concentrations were also observed. Daytime maxima in ozone concentration were recorded between 1200 and 1400 h, whereas morning and evening hours showed lower concentrations of ozone. Ozone concentrations in the atmosphere depended on several meteorological factors. Monthly average ozone concentration was significantly correlated with maximum temperature (p<0.001) and mean monthly temperature (p<0.05), maximum relative humidity (p<0.001), minimum relative humidity (p<0.001) and mean monthly relative humidity (p<0.001), and sunshine hours (p<0.001). Ozone concentrations in the ambient air have shown an increase in the past decade that was more in the winter and rainy seasons than in the summer. This study suggests that ozone concentrations around Varanasi were sufficiently high to cause significant damage to agricultural production. The present work can be extended to a regional level by incorporating modelling studies using recent remote sensing tools.     

Satellite- and ground-based measurements of CO2 over the Indian region: its seasonal dependencies,spatial variability,and model estimates

ABSTRACT

The present study demonstrates the distribution of carbon dioxide (CO₂) concentration over the Indian region and the surrounding oceanic regions during 2009–2012, using measurements from satellites viz., Greenhouse Gases Observing Satellite (GOSAT) and Atmospheric Infrared Sounder, Carbon Tracker (CT) model simulations and flask measurements from two Indian stations Sinhagad (SNG) (73°45′ E, 18°21′36″ N) and Cape Rama (CRI) (73°54′ E, 15°6′ N). The concentration of CO₂ is observed to be maximum during pre-monsoon and shows a decreasing phase during the post-monsoon season. In a regional scale, it is found that Indo-Gangetic Plain and northern India have relatively higher concentrations compared to the other regions. The probability distribution of the concentration differences shows that for most of the time, the differences lie between ±3 ppmv between GOSAT and CT. The comparison between the CO₂ flask measurements over SNG and CRI with respect to that of GOSAT and CT clearly reveals that the differences in CO₂ are as high as 10 ppmv between the ground- and satellite-based measurements. Further, we utilized the Lagrangian model FLEXible PARTicle (FLEXPART) to understand the source?receptor relationship over CRI, SNG, and over the equatorial Indian Ocean (IO). The source contributions from the northern and eastern continental regions of the Indian region are found to be more influential over SNG compared to CRI. It is also found from simulations that the equatorial IO has less influence from the continental source and therefore has a reduced seasonal variability compared to the other regions considered in the present study.     

Study on coke size degradation from coke plant wharf to blast furnaces stock house

The gas permeability, which is one of the most important requirements served by coke, is dependent largely on the size distribution of the coke at the various zones in the blast furnace. This papers deals with breakage of coke when it travels from wharf to blast furnace. In this study, six different coal blend samples in the range of 23.6–25.0% volatile matter and 11.7–14.8% ash were studied in stamp charged coke making process (wet bulk density 1.15 t/m³). The coke samples were collected from battery no. 8 wharf, CK06 (conveyer belt) and auto sampler. All experiments were conducted on shatter machine and an attempt has been made to find out reasons for breakage of coke. Results indicate that the coke size degradation is function of transporting system and dropping height of coke from wharf to blast furnace. It was also found that in stamp charging condition, it is possible to improve yield of blast furnace grade coke even at higher composition balance index of coal blend (2.94–3.70).     

Centered inclined slot coupling between waveguides with coplanar axes

The article presents the method of finding the complete equivalent circuit of two waveguides with coplanar axes coupled through a centered inclined slot in the common broad wall. The variational method based on dyadic Green's function is used for finding the parameters of the equivalent circuit. A cosinusoidal aperture field distribution is assumed. Considerable mathematical simplification is resulted from replacing the centered inclined slot by an equivalent magnetic dipole. Coupling slot characteristics are deduced, including resonant length, dominant mode scattering in both the waveguides. Numerical and experimental results for resonant lengths and scattering parameters are presented over a range of tilt angles, frequencies, and waveguide dimensions. These results have significant applications in linear waveguide arrays and coupler design. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Efficiency of Urban Water Supply Utilities in India

The two parameters of services output of water utilities are the per capita water available for consumption and the hours for which water is supplied per day. However, water utilities in India differ on the level of these outputs substantially. This paper uses the data for water utilities in 31 cities to analyse their performance in delivery of services. Using data envelopment analysis, a measure of technical efficiency for various utilities is calculated. The results indicate that water utilities can increase the delivery of water on a per capita basis and increase the hours of supply per day by about 18%. Nearly 37% of the increase in services could result from changing the scale of operation. This paper also discusses if the institutional framework within which these utilities operate has implications on their efficiency.     

Solar radiation models—A review

Solar radiation models for predicting the average daily and hourly global radiation, beam radiation and diffuse radiation on horizontal surface are reviewed in this article. Estimations of monthly average hourly global radiation from daily summations are discussed. It was observed that Collares‐Pereira and Rabl model as modified by Gueymard (CPRG) yielded the best performance for estimating mean hourly global radiation incident on a horizontal surface for Indian regions. Estimations of monthly average hourly beam and diffuse radiation are discussed. It was observed that Singh‐Tiwari and Jamil‐Tiwari both models generally give better results for climatic conditions of Indian regions. Therefore, their use is recommended for composite climate of Indian regions. Empirical correlations developed to establish a relationship between the hourly diffuse fraction and the hourly clearness index using hourly global and diffuse irradiation measurements on a horizontal surface are discussed. Fifty models using the Angstrom–Prescott equation to predict the average daily global radiation with hours of sunshine are considered. It was reported that Ertekin and Yaldiz model showed the best performance against measured data of Konya, Turkey. Copyright © 2010 John Wiley & Sons, Ltd.     

The development of low-temperature hardening silicone ceramer coatings for the corrosion protection of metals

The process parameters for the formulation of two different hybrid ceramic-polymer (ceramer), barrier-type coatings for the corrosion protection of metals are discussed. The coating formulations were characterized in the liquid, gel, and solid phases using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and Secondary Ion Mass Spectroscopy (SIMS), respectively. The coatings were applied to 6061-T6 aluminum alloy, hardened in ambient conditions, and analyzed with X-ray photoelectron spectroscopy (XPS). Thermal stability of the coatings was analyzed in inert and oxidative atmosphere using thermogravimertic analysis. The final surface morphology was studied using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). The nanoindentation technique supported by SEM revealed the nanomechanical properties of the coatings. The effectiveness as a barrier-type coating was studied using electrochemical polarization experiments and immersion experiments in saline solution.     

A passive auxiliary circuit achieves zero-voltage-switching in full-bridge converter over entire conversion range

A passive auxiliary circuit is proposed to achieve zero-voltage-switching (ZVS) over the entire conversion range in a full-bridge (FB) pulse-width modulated (PWM) converter (FBZVS converter) with minimum conduction loss penalty. The stored energy in the auxiliary circuit is minimal under the full-load condition. It increases progressively as the load current decreases. The proposed auxiliary circuit is passive, simple and can be viewed as an add-on to the conventional FBZVS converter. The principle of operation is described and the performance is demonstrated on a 100 kHz, 500 W prototype.