Multiple Linear Correlation Analysis 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. Simple regression techniques, may sometimes, provide adequate estimation of ET₀. Implementation of regression methods considering all the predictor variables may, however, lead to overfit and consequent reduction in the predictive capability. The regression models for ET₀ have been developed in the present study for Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar regions of Andhra Pradesh, India by following step-wise procedure, eliminating superfluous predictor variables based on statistical criteria. The sunshine hours, wind velocity, temperature and relative humidity influenced ET₀ in the study area. The linear regression models developed in terms of predictor variables may conveniently be applied in the regions selected for the present study and, in the regions with similar climatic conditions for satisfactory ET₀ estimation.     

Synthesis and properties of electrodeposited Ni/ceria nanocomposite coatings

Composite plating is a method of co-depositing fine particles of metallic or non-metallic compounds or polymers in the plated layer to improve material properties such as lubrication, wear resistance and corrosion resistance. In the present study, Ni was chosen as the matrix material and ceria nanoparticles were chosen as the distributed phase. Nanocrystalline ceria powder was synthesized by the solution combustion process and characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanosize ceria particles were co-deposited with nickel from a nickel sulfamate bath using conventional electrodeposition method. The electrodeposition was carried out at current densities of 0.23, 0.77, 1.55, 3.1 and 5.4 A/dm². The microhardness of the Ni matrix was enhanced by the incorporation of ceria particles. Potentiodynamic polarization, electrochemical impedance spectroscopy and SEM were used to characterize the corrosion behaviour of Ni and Ni/CeO₂ coatings. These studies showed improved corrosion resistance for Ni/CeO₂ when compared to Ni. The microhardness, corrosion resistance and wear resistance of Ni and Ni/CeO₂ were compared.     

Optical absorption spectrum of Cr3 ions in sodium ammonium sulphate dihydrate single crystal

Optical absorption spectrum of Cr³⁺ ions doped in sodium ammonium sulphate dihydrate single crystal has been studied both at room and liquid nitrogen temperatures. The observed bands were explained satisfactorily assuming octahedral symmetry for the Cr³⁺ ion in the crystal. The crystal field parameters Dq = 1750 cm^-1, B = 735 cm^-1 and C = 3220 cm^-1 are found to give a good fit to the observed band positions.     

A review of urban energy system models: Approaches,challenges and opportunities

Energy use in cities has attracted significant research in recent years. However such a broad topic inevitably results in number of alternative interpretations of the problem domain and the modelling tools used in its study. This paper seeks to pull together these strands by proposing a theoretical definition of an urban energy system model and then evaluating the state of current practice. Drawing on a review of 219 papers, five key areas of practice were identified – technology design, building design, urban climate, systems design, and policy assessment – each with distinct and incomplete interpretations of the problem domain. We also highlight a sixth field, land use and transportation modelling, which has direct relevance to the use of energy in cities but has been somewhat overlooked by the literature to date. Despite their diversity, these approaches to urban energy system modelling share four common challenges in understanding model complexity, data quality and uncertainty, model integration, and policy relevance. We then examine the opportunities for improving current practice in urban energy systems modelling, focusing on the potential of sensitivity analysis and cloud computing, data collection and integration techniques, and the use of activity-based modelling as an integrating framework. The results indicate that there is significant potential for urban energy systems modelling to move beyond single disciplinary approaches towards a sophisticated integrated perspective that more fully captures the theoretical intricacy of urban energy systems.     

Development and Characterization of Water-Blown Polyurethane Foams from Diethanolamides of Karanja Oil

The present study focuses on the use of renewable resource, namely karanja oil for the development of polyurethane foams. The non-edible oil was chemically modified into the diethanolamide by hydroxylation followed by transamidation. The structure of the diethanolamide was confirmed by proton nuclear magnetic resonance spectroscopy, infrared spectroscopy and gas chromatography–mass spectrometry and used as polyol to prepare water-blown polyurethane foams. Polyurethane foams were produced with carbon dioxide as the blowing agent generated by the reaction between excess polymeric MDI with water. Foams were prepared by a hand mixing process which involved blending of the diethanolamide with polypropylene glycol, polymeric MDI, water, catalyst and surfactant. The hydroxyamide content, catalyst nature and molecular weight of polypropylene glycol were varied and the effect on the properties was studied. Foam rise time and other physical properties such as density, compression strength and flexural strength were evaluated. Optical microscopy was used to study the morphology to reveal the closed cell nature and other structure–property relationships.     

Low temperature assisted chemical coprecipitation synthesis of 8YSZ plasma sprayable powder for solid oxide fuel cells

Plasma spraying is one of the potential manufacturing technologies widely used in tubular solid oxide fuel cells (SOFC) fabrication. The plasma spray technology requires powders with good flowability and large particle size (5-200 μm). A simple, low temperature assisted chemical process was used for the preparation of plasma grade yttria stabilized zirconia powder without any agglomeration process. The powder was characterized by X-ray diffractometry, particle size analysis, scanning electron microscopy and Raman spectroscopy. The powder exhibited cubic phase, good flowability and blocky angular shape. The 8YSZ powder was plasma sprayed and the coatings after sintering showed gas tightness (gas leak rate ∼ 1 × 10⁻⁶ mbar l s⁻¹ cm²). This was substantiated by the presence of densely packed grains as seen in the surface FESEM image of the sintered plasma sprayed 8YSZ free form. Conductivity values in par with the values reported in literature were obtained for plasma sprayed 8YSZ coating.     

4“-O-Alkylated α-Galactosylceramide Analogues as iNKT-Cell Antigens: Synthetic,Biological, and Structural Studies

Invariant natural killer T-cells (iNKT) are a glycolipid-responsive subset of T-lymphocytes that fulfill a pivotal role in the immune system. The archetypical synthetic glycolipid, α-galactosylceramide (α-GalCer), whose molecular framework is inspired by a group of amphiphilic natural products, remains the most studied antigen for iNKT-cells. Nonetheless, the potential of α-GalCer as an immunostimulating agent is compromised by the fact that this glycolipid elicits simultaneous secretion of Th1- and Th2-cytokines. This has incited medicinal chemistry efforts to identify analogues that are able to perturb the Th1/Th2 balance. In this work, we present the synthesis of an extensive set of 4“-O-alkylated α-GalCer analogues, which were evaluated in vivo for their cytokine induction. We have found that conversion of the 4”-OH group to ether moieties decreases the immunogenic potential in mice relative to α-GalCer. Yet, the benzyl-modified glycolipids are able to produce a distinct pro-inflammatory immune response. The crystal structures suggest an extra hydrophobic interaction between the benzyl moiety and the α2-helix of CD1d.     

Energy-Efficient Power Allocation with Guaranteed QoS Under Imperfect Sensing for OFDM-Based Heterogeneous Cognitive Radio Networks

Wireless Personal Communications - This paper investigates the energy efficient resource allocation scheme for orthogonal frequency division multiplexing based heterogeneous cognitive radio network...