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1.
Prakashan Chellattan Veettil Stijn Speelman Guido van Huylenbroeck 《Water Resources Management》2013,27(1):55-73
By introducing proper pricing instruments, farm level water can be used more efficient. But it demands a proper estimation strategy to analyse the efficiency and the input use behavior of farms under the new pricing system. As most production relationships are stochastic in nature, excluding random errors and noise from model specifications often leads to criticism. By using a probabilistically constrained programming formulation, an empirical estimation of stochastic data envelopment analysis (DEA) is done to analyze the efficiency of irrigation water use in the agricultural production system in the Krishna river basin, India. The results illustrate that water demand is higher for farms at, or close to the frontier and lower for those with low efficiency levels. In a second step, a simulation model is developed by using the frontier and economic efficiency derived from stochastic DEA to analyse the impact of water pricing on water use efficiency and water use behaviour. It is shown that an increase in the water price would not cause sizeable profit loss, if the pricing system is administered on a volumetric basis, but water demand would decrease substantially. 相似文献
2.
Kottila Veettil Dhaneesh Mohan GopiRaghunathan Ganeshamurthy Thipramalai Thankappan Ajith KumarThangavel Balasubramanian 《Food chemistry》2012,131(3):985-991
Tissue samples of marine organisms from the coastal waters of Agatti Island were subjected to analysis of metals (cadmium, cobalt, copper, iron, magnesium, manganese, nickel, lead and zinc), using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) for the assessment of the present condition of the Island ecosystem and compiling the baseline data for future monitoring, with respect of metal accumulation of marine organisms. Tissue samples of fish, shellfish and seaweed revealed that the metals have different levels of accumulation viz. Cd = 0.08-0.14, Co = 0.01-0.02, Cu = 0.16-0.98, Fe = 3.19-5.3, Mg = 86.73-152.45, Mn = 0.17-0.55, Ni = 0.06-0.26, Pb = 0.11-0.46 and Zn = 3.26-14.2 μg g−1 dry wt. Metal concentrations were more in shellfish and less in finfish. Concentrations of toxic metals such as Cd, Co, Ni and Pb were well below the permissible limits proposed by the World Health Organization. 相似文献
3.
Hari Krishna Varma P. Krishna Pillai Themanam Veettil Mani Krishna Gopa Kumara Warrier Alathoor D. Damodaran 《Journal of the American Ceramic Society》1994,77(1):129-132
Conditions for obtaining a stable sol in an isopropyl alcohol–water medium containing titanium isopropoxide and strontium nitrate, and acetic acid as a modifier, have been described. Spray drying of the sol results in submicrometer spherical agglomerates which on further thermal decomposition yield submicrometer particles of strontium titanate at temperatures as low as 500°C. The thermal decomposition characteristics of the spray-dried precursor and the development of strontium titanate phase have been discussed. Calcined precursor powder possesses a specific surface area of 12m2 /g, a comp action density of 57%, and a sintered density of > 98%. The optimum sintering temperature of such a powder was 1450°C, which resulted in a sintered grain size around 1.5 μm. Further, such a sintered sample had a dielectric constant of 260 and a loss factor of 0.008 at 1 kHz. This method appears to be very convenient with respect to handling of stable sols and thus avoids the usual difficulties regarding extended gelation as well as inhomogeneous precipitation. 相似文献
4.
Li Zou Huan Li Dan Wang Leyuan Ma Kundil Prakashan Zhen Xiu Zhang 《Polymer Engineering and Science》2020,60(1):211-217
Toughed polypropylene (PP) foams, with the combination of blending with trans-1,4-polyisoprene (TPI) and micro/nanocellular structure in the matrix, were prepared using a batch foaming process and N2 as the blowing agent. The incorporation of TPI in the PP matrix induces the enhanced formability and the slightly improved ductility and toughness compared to the neat PP. The simultaneous existence of the TPI phase and micro/nanocellular structure makes the fracture behavior follow the shear yielding of a bundle of fibrils in the tensile load direction. The results of mechanical properties measurements show that the notched Izod impact strengths of foamed PP/TPI blend are two to three times larger than those of the unfoamed counterparts. The PP/TPI blend foam with 5phr TPI content shows the highest impact strength when the foaming temperature is 140°C, which is fivefold increase over that of the neat PP. The enhanced ductility and toughness of PP/TPI foams were found with the increasing foaming temperature. The insert of micro−/nanocellular in PP/TPI blends simultaneously makes the notched impact strength increase significantly, tensile strength decrease, and elongation at break increase obviously, which provides the possibility to combine the higher impact strength and toughness with the advantage of microcellular foaming. POLYM. ENG. SCI., 60:211–217, 2020. © 2019 Society of Plastics Engineers 相似文献
5.
Microcellular foaming of chlorosulfonated polyethylene rubber and its kaolin‐filled compounds with supercritical nitrogen 下载免费PDF全文
The microcellular foaming of vulcanizates made from chlorosulfonated polyethylene (CSM) rubber and its kaolin‐filled compounds was carried out with supercritical nitrogen. The effects of various curing times, temperatures of the vulcanizates, and kaolin filler contents in the vulcanizates on the prepared foams were studied. The foaming of the vulcanizates with various crosslinking densities revealed the critical effect the crosslinking density of the CSM matrix played on its foaming. A certain sufficient level of crosslinking density was most effective for the foaming of the matrix; a higher crosslinking density led to a decreased cell size, increased cell density, and decreased matrix expansion in the foams. The effect of the crosslinking density was due to its effect on the free volume of the elastomeric matrix, which controlled the gas diffusion from the matrix during the pressure‐release stage of the foaming operation. The incorporation of kaolin decreased the cell size and increased the cell density of the foams; the decreased free volume and the heterogeneous cell nucleation effect of the kaolin contributed to this. The tensile strength of the foams significantly improved with increasing kaolin content in the foams. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45656. 相似文献
6.
Krishna Gopa Kumara Warrier Hari Krishna Varma Themanam Veettil Mani Alathoor Damodaran Damodaran 《Journal of the American Ceramic Society》1992,75(7):1990-1992
A novel and rapid method to prepare 123 superconductor powder based on microwave processing is reported. A mixture of the nitrates of Y, Ba, and Cu in 123 stoichiometry when subjected to microwaves of frequency 2.45 GHz for 240 s resulted in an appreciable quantity of tetragonal 123 phase. Annealing for a period of 4 h at 940°C in flowing oxygen formed a superconductor having a T c of 91 K. Sintered pellets of the powder formed by microwave processing have shown transport J c of 105 A/cm2 . 相似文献
7.
Physicomechanical,friction, and abrasion properties of EVA/PU blend foams foamed by supercritical nitrogen 下载免费PDF全文
Zhen Xiu Zhang Tao Zhang Dan Wang Xin Zhang Zhenxiang Xin K. Prakashan 《Polymer Engineering and Science》2018,58(5):673-682
Elastomer foams based on EVA, PU, and EVA/PU blends formulated for shoe‐sole applications were prepared by a supercritical N2 batch foaming process and characterized for physicomechanical, friction and abrasion properties. The blending of EVA with PU was aimed for improving the friction and wear characteristics of the EVA based foams. All of the foams prepared showed spherical cells with closed‐cell morphology and the cell sizes varied with varying the EVA/PU blend ratio and CaCO3 content of the foams. The properties such as hardness and resilience, friction coefficients and abrasion resistance improved for the EVA/PU blend foams compared to the EVA foam, but their compression set, tensile strength, and tear strength were inferior to the EVA foam. The incorporation of CaCO3 filler increased density, hardness, tensile strength, and tear strength of the EVA/PU blend foams but decreased resilience, compression set, friction coefficients, and abrasion resistance. The improvement in friction coefficients and wear resistance obtained in the EVA/PU blend foams was significant for shoe‐sole applications. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers 相似文献
8.
Ternary composites of polypropylene (PP), polydimethylsiloxane (PDMS) elastomer, and nano‐SiO2, prepared with three different mixing sequences, were studied for dispersion morphology and its effect on the crystallization of PP and the mechanical properties. The mixing sequence produced a significant effect on the dispersion morphology and, thereby, on the mechanical properties of the composites. A two‐step mixing sequence, in which nano‐SiO2 was added in the second step to the PP/PDMS binary system, produced a significant encapsulation of nano‐SiO2 by PDMS, and this, in turn, resulted in the poor modulus and impact strength of the composite. A one‐step mixing sequence of all three components produced a separated dispersion of PDMS and nano‐SiO2 phases in the PP matrix with the occurrence of a fine band of nano‐SiO2 particles at the boundaries of the PDMS domains and the presence of some nano‐SiO2 filler particles inside the PDMS domains. This one‐step mixing sequence produced an improvement in the tensile modulus but a decrease in the impact strength with increasing nano‐SiO2 content. In the third sequence of mixing, which involved a two‐step mixing sequence through the addition of PDMS in the second step to the previously prepared PP/nano‐SiO2 binary system, the morphology of the dispersion showed separately dispersed PDMS and nano‐SiO2 phases with a loose network of nano‐SiO2 particles surrounding the PDMS domains. This latter series of ternary composites had the highest impact strength and exhibited high shear deformation under tensile and impact conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
9.
Effect of dispersion morphology, resulting from different mixing sequences used in making ternary composite polypropylene (PP)/poly(dimethylsiloxane) (PDMS)/nano SiO2, on the crystallization of PP phase is studied. Mixing sequence is found to have significant effect on the dispersion morphology of the ternary composite, which in turn affected the crystallization of the PP matrix of the ternary composite. Crystallization behaviour of PP, studied by the differential scanning calorimetry, is discussed for the effect of different dispersion morphologies on overall crystallization process rate, nucleation rate, crystal size distribution and crystallinity. 相似文献
10.
Modification of poovan banana (Musa AAB) starch by γ‐irradiation: effect on in vitro digestibility,molecular structure and physico‐chemical properties 下载免费PDF全文
Chagam Koteswara Reddy Puthan Veettil Vidya Korambeth Vijina Sundaramoorthy Haripriya 《International Journal of Food Science & Technology》2015,50(8):1778-1784
This study focussed at evaluating the effect of gamma irradiation on the in vitro digestibility, molecular structure and physico‐chemical properties of poovan banana (Musa AAB) starch using γ‐rays from a 60Co source at different doses with a dose rate of 2 kGy h?1. Physico‐chemical properties varied significantly and exhibited strong dose‐dependent relationship. Escalating irradiation leads to decrease in amylose content, pH, swelling power of the starch granules and syneresis of the gelatinised starch, while the same led to an increase in carboxyl content, in vitro digestibility, solubility and water absorption capacity of the starch granules. The results revealed that peak, hold, final and setback viscosities were significantly reduced. X‐ray diffraction pattern remained the same upon irradiation but a decrease in relative crystallinity was observed with increasing irradiation dose. Gelatinisation temperature and enthalpy decreased significantly when the increasing the dose of gamma irradiation. 相似文献