Scanning electron microscopy studies of failure surfaces of short glass fibre — rubber composites

The failure surfaces of short-glass fibre reinforced rubber composites have been examined by scanning electron microscopy. The tensile, tear, flexing and abrasion modes have been studied. The different modes generate typical fracture surfaces depending on the nature of the test. The technical properties of the composites with and without reinforcing carbon-black filler have been explained on the basis of fracture modes. For comparison, mixes without fibre have also been studied.     

Thermodynamic analysis of R 21-DMF vapour absorption refrigeration systems for solar energy applicationsAnalyse thermodynamique des systèmes frigorifiques à absorption de R 21-DMF (diméthylformamide) pour les applications à l'énergie solaire

The concentration-enthalpy chart for R 21-DMF refrigerant-absorbent combination is presented for the temperature range of interest for solar-driven cooling applications. A thermodynamic analysis of the vapour absorption refrigeration system (VARS) working with R 21-DMF is made to study the theoretical performance characteristics. At evaporator temperatures lower than about 0°C, R 21-DMF has a distinct advantage over R 22-DMF systems in being able to operate at lower generator temperatures. Also R 21-DMF systems perform better than R 22-DMETEG systems.     

Inhibition by adenosine triphosphate of heart microsomal neutral lipase activity

Triacylglycerol lipolysis was inhibited by palmitate, in the isolated perfused normal rat heart. Acetate or acetylcarnitine could reproduce the inhibitory effects of palmitate. Since heart neutral lipase plays an important role in the lipolysis of heart triacylglycerols, the effects of acetylcarnitine, acetyl CoA and related metabolites on the microsomal neutral lipase activity were studied. ATP inhibited the enzyme activity in a concentration-dependent manner without a lag phase. AMP and adenylyl imidodiphosphate, two compounds structurally related to ATP but whose phosphate groups cannot be transferred, did not inhibit the microsomal lipase activity. These results suggested that ATP inhibited the lipase activity through the transfer of its phosphate group. It is proposed that cellular ATP concentration is a determinant of tricylglycerol lipolysis in the heart.     

Quantization Methods for Equal Gain Transmission With Finite Rate Feedback

We consider the design and analysis of quantizers for equal gain transmission (EGT) systems with finite rate feedback-based communication in flat-fading multiple input single output (MISO) systems. EGT is a beamforming technique that maximizes the MISO channel capacity when there is an equal power-per-antenna constraint at the transmitter, and requires the feedback of t-1 phase angles, when there are t antennas at the transmitter. In this paper, we contrast two popular approaches for quantizing the phase angles: vector quantization (VQ) and scalar quantization (SQ). On the VQ side, using the capacity loss with respect to EGT with perfect channel information at transmitter as performance metric, we develop a criterion for designing the beamforming codebook for quantized EGT (Q-EGT). We also propose an iterative algorithm based on the well-known generalized Lloyd algorithm, for computing the beamforming vector codebook. On the analytical side, we study the performance of Q-EGT and derive closed-form expressions for the performance in terms of capacity loss and outage probability in the case of i.i.d. Rayleigh flat-fading channels. On the SQ side, assuming uniform scalar quantization and i.i.d. Rayleigh flat-fading channels, we derive the high-resolution performance of quantized EGT and contrast the performance with that of VQ. We find that although both VQ and SQ achieve the same rate of convergence (to the capacity with perfect feedback) as the number of feedback bits B increases, there exists a fixed gap between the two     

Performance of Recalibrated Equations for the Estimation of Daily Reference Evapotranspiration

An accurate estimation of reference evapotranspiration (ET₀) is of paramount importance for many studies such as hydrologic water balance, irrigation system design and management, crop yield simulation, and water resources planning and management. In the present study, Blaney-Criddle, Jensen-Haise and Hargreaves (temperature based), Priestley-Taylor, Radiation and Makkink (radiation based) and, Pan Evaporation and Christiansen (pan evaporation based) methods have been evaluated and recalibrated with respect to FAO-56 Penman-Monteith method for estimating daily ET₀ in the semi-arid Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar sites of Andhra Pradesh, India. Recalibrated Blaney-Criddle (temperature based), Radiation (Radiation based) and Christiansen (Pan evaporation based) methods showed a satisfactory performance at the sites. Further, recalibrated Blaney- Criddle method showed relatively better performance than Radiation and Christiansen methods in the daily ET₀ estimation. Recalibrated Blaney- Criddle method may therefore be adopted at the sites selected for the present study and also at the sites with similar climatic conditions for satisfactory daily ET₀ estimation.     

Ground water potential in a semi-arid region of Andhra Pradesh - a geographical information system approach

Continuous and adequate supplies of potable water from ground reservoirs are important for sustained agriculture, industry and domestic use throughout huge semi-arid regions of India. The present paper describes an approach to investigating groundwater potential over extensive geographical areas and illustrates its potential with reference to watershed planning in the large Varaha River Basin (VRB), Andhra Pradesh, India. The method involves the creation of a systematic database of information from satellite data for reconnaissance survey before going for field exploration. Colour composite images from Landsat Thematic Mapper and Indian Remote Sensing (IRS) satellite were used to interpret various thematic maps of the Varaha river basin. SPOT 1 MLA data of band 3 on a 1:250 000 scale was used for improving the accuracy of interpretation of topographic units due to its higher resolution and stereo coverage. Slope and other coverages were derived from topographic maps. The thematic and topographic information was digitized and ERDAS Imagine GIS software was used to analyse this information. Groundwater potential zones were delineated through subjective weights assigned to interpreted thematic and derived topographic units according to their likely infiltration capacities. Seven categories of groundwater potential ranging from very good to poor were derived automatically. Field measurements were then made within a selection of these categories to check the groundwater potential at selected sites. The validity and effectiveness of using remote sensing and GIS techniques for improving the targeting of field observations for groundwater for a huge river basin is shown by comparing the inferred groundwater potential with the field measurements.     

An effective hybrid approach to remote-sensing image classification

This article presents a hybrid fuzzy classifier for effective land-use/land-cover (LULC) mapping. It discusses a Bayesian method of incorporating spatial contextual information into the fuzzy noise classifier (FNC). The FNC was chosen as it detects noise using spectral information more efficiently than its fuzzy counterparts. The spatial information at the level of the second-order pixel neighbourhood was modelled using Markov random fields (MRFs). Spatial contextual information was added to the MRF using different adaptive interaction functions. These help to avoid over-smoothing at the class boundaries. The hybrid classifier was applied to advanced wide-field sensor (AWiFS) and linear imaging self-scanning sensor-III (LISS-III) images from a rural area in India. Validation was done with a LISS-IV image from the same area. The highest increase in accuracy among the adaptive functions was 4.1% and 2.1% for AWiFS and LISS-III images, respectively. The paper concludes that incorporation of spatial contextual information into the fuzzy noise classifier helps in achieving a more realistic and accurate classification of satellite images.     

Multi‐criteria decision evaluation in groundwater zones identification in Moyale‐Teltele subbasin,South Ethiopia

The conventional approaches such as ground‐based surveys and exploratory drilling for groundwater investigation are time‐consuming and uneconomical. Systematic organisation of data of characteristics of any terrain, evaluation of inter‐thematic, interclass dependencies and variability, and also analysing cumulative effect on the development of groundwater regime is the best approach which the current decade requires. This is proved by generation of the thematic information on the above factors through remote sensing technique, and integration in geographic information system (GIS) for evaluation using multi‐criteria decision‐making techniques. This paper presents the results of the attempt made to identify the groundwater potential zones in the Moyale‐Teltele Sub basin of the Genale Dawa River Basin in South Ethiopia using the integrated approaches of remote sensing and geographic information systems. Six geologic, physiographic, and hydrologic factors were applied namely: lithology, structure, geomorphology, slope, land cover, and drainage. Weighted Overlay Analysis using multicriteria decision technique is implemented to produce the groundwater potential map of the area. This result is further verified by groundwater yield data of boreholes and springs collected in the field and from previous reports. The validation revealed that the result is in good conformity with the actual yield of the wells and springs.     

Satellite derived crop calendar for canal operation schedule in Bhadra project command area,India

Spatial information on crop calendars in the command areas of irrigation systems is useful to irrigation engineers in order to achieve chronological synchronization between water delivery pattern and crop life cycle. Such synchronization is vital for efficient use of water. The capability of satellite remote sensing technology to generate spatial crop calendar information in an irrigated command area and its usefulness in the evaluation of water delivery patterns are demonstrated in this paper. The study pertains to the major crop paddy during the rabi season (December to June) of 1992-93, in the Bhadra project command area of Karnataka state, India. Analyses of multidate Normalized Difference Vegetation Index (NDVI) profiles of paddy crop generated from Indian Remote Sensing (IRS) satellite data for each distributary command reveal three distinct growth patterns in the study area with each pattern characterized by a particular crop calendar. The spatial variability in crop calendar over the total command area has thus been derived. The ground truth data obtained in crop cutting experiments (CCEs) validate the satellite derived crop calendar. Distributary wise, water delivery data have been studied in conjunction with the satellite derived crop calendar to determine whether the existing pattern of water delivery covers the required length of crop life cycle in the command area. It was found that the water supply was stopped about 30 days before harvesting in some distributaries and in some about 20-30 days before harvesting. A list of distributaries with greater lags between cessation of water supply and crop harvest was provided to irrigation system engineers to aid their plans for providing a reliable and predictable irrigation service. This is possible either through reorganization of canal operation schedule or through educating farmers about the need for adjusting their agricultural activities to match water supply patterns.