Effect of a booster mirror on the performance of a ‘built-in’ storage solar water heater

In this paper, the performance of a ‘built-in’ storage solar water heater-flat mirror system has been presented. Numerical calculations have been made for a typical cold day (viz. 28 Jan. 1980) at Delhi. The booster mirror causes a minimum temperature rise during the moring and a temperature difference of 7°C excess with respect to the reference panel occurred. The reflectance of the mirror is taken as 0·88.     

Process control in CNC manufacturing for discrete components: A STEP-NC compliant framework

With today's highly competitive global manufacturing marketplace, the pressure for right-first-time manufacture has never been so high. New emerging data standards combined with machine data collection methods, such as in-process verification lead the way to a complete paradigm shift from the traditional manufacturing and inspection to intelligent networked process control. Low-level G and M codes offer very limited information on machine capabilities or work piece characteristics which consequently, results in no information being available on manufacturing processes, inspection plans and work piece attributes in terms of tolerances, etc. and design features to computer numerically controlled (CNC) machines. One solution to the aforementioned problems is using STEP-NC (ISO 14649) suite of standards, which aim to provide higher-level information for process control. In this paper, the authors provide a definition for process control in CNC manufacturing and identify the challenges in achieving process control in current CNC manufacturing scenario. The paper then introduces a STEP-compliant framework that makes use of self-learning algorithms that enable the manufacturing system to learn from previous data and results in eliminating the errors and consistently producing quality products. The framework relies on knowledge discovery methods such as data mining encapsulated in a process analyser to derive rules for corrective measures to control the manufacturing process. The design for the knowledge-based process analyser and the various process control mechanisms conclude the paper.     

Influence of calcination conditions on phase formation and particle size of indium niobate powders synthesized by the solid-state reaction

A wolframite-type phase of indium niobate, InNbO₄, has been synthesized by a solid-state reaction via a rapid vibro-milling technique. The formation of the InNbO₄ phase in the calcined powders has been investigated as a function of calcination conditions by TG-DTA and XRD techniques. Morphology, particle size and chemical composition have been determined via a combination of SEM and EDX techniques. Single-phase InNbO₄ powders have been obtained successfully for calcination condition of 900 °C for 4 h or 950 °C for 2 h with heating/cooling rates of 30 °C/min. Higher temperatures and longer dwell times clearly favoured particle growth and the formation of large and hard agglomerates.     

Wavelet Bootstrap Multiple Linear Regression Based Hybrid Modeling for Daily River Discharge Forecasting

A new hybrid model, the wavelet–bootstrap–multiple linear regression (WBMLR) is proposed to explore the potential of wavelet analysis and bootstrap resampling techniques for daily discharge forecasting. The performance of the developed WBMLR model is also compared with five more models: multiple linear regression (MLR), artificial neural network (ANN), wavelet-based MLR (WMLR), wavelet-based ANN (WANN) and wavelet–bootstrap–ANN (WBANN) models. Seven years of discharge data from seven gauging stations in the middle reaches of Mahanadi river basin in India are applied in this study. Significant input vectors are decomposed into discrete wavelet components (DWCs) using discrete wavelet transformation (DWT) to generate wavelet sub time series that are used as inputs to the MLR and ANN models to develop the WMLR and WANN models, respectively. Effective wavelets are selected by considering several types of wavelets with different vanishing moments. WBMLR and WBANN models are developed as ensemble of different WMLR and WANN models, respectively, developed using different realizations of the training dataset generated using bootstrap resampling technique. The results show that the wavelet bootstrap hybrid models (i.e. WBMLR and WBANN) produce significantly better results than the traditional MLR and ANN models. Hybrid models based on MLR (WMLR, WBMLR) perform better than the ANN based hybrid models (WBANN, WANN). The WBMLR and WMLR models simulate the peak discharges better than the WBANN, WANN, MLR and ANN models, whereas the overall performance of WBMLR model is found to be more accurate and reliable than the remaining five models.     

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.