Hybrid moving block bootstrap for stochastic simulation of multi-site multi-season streamflows

The Hybrid approach introduced by the authors for at-site modeling of annual and periodic streamflows in earlier works is extended to simulate multi-site multi-season streamflows. It bears significance in integrated river basin planning studies. This hybrid model involves: (i) partial pre-whitening of standardized multi-season streamflows at each site using a parsimonious linear periodic model; (ii) contemporaneous resampling of the resulting residuals with an appropriate block size, using moving block bootstrap (non-parametric, NP) technique; and (iii) post-blackening the bootstrapped innovation series at each site, by adding the corresponding parametric model component for the site, to obtain generated streamflows at each of the sites. It gains significantly by effectively utilizing the merits of both parametric and NP models. It is able to reproduce various statistics, including the dependence relationships at both spatial and temporal levels without using any normalizing transformations and/or adjustment procedures. The potential of the hybrid model in reproducing a wide variety of statistics including the run characteristics, is demonstrated through an application for multi-site streamflow generation in the Upper Cauvery river basin, Southern India. (C) 2004 Elsevier B.V. All rights reserved.

Shrewd alliances: mixed foraging associations between treeshrews,greater racket-tailed drongos and sparrowhawks on Great Nicobar Island, India

Mixed-species foraging associations may form to enhance feeding success or to avoid predators. We report the costs and consequences of an unusual foraging association between an endemic foliage gleaning tupaid (Nicobar treeshrew Tupaia nicobarica) and two species of birds; one an insectivorous commensal (greater racket-tailed drongo Dicrurus paradiseus) and the other a diurnal raptor and potential predator (Accipiter sp.). In an alliance driven, and perhaps engineered, by drongos, these species formed cohesive groups with predictable relationships. Treeshrew breeding pairs were found more frequently than solitary individuals with sparrowhawks and were more likely to tolerate sparrowhawks in the presence of drongos. Treeshrews maintained greater distances from sparrowhawks than drongos, and permitted the raptors to come closer when drongos were present. Treeshrew foraging rates declined in the presence of drongos; however, the latter may provide them predator avoidance benefits. The choice of the raptor to join the association is intriguing; particular environmental resource states may drive the evolution of such behavioural strategies. Although foraging benefits seem to be the primary driver of this association, predator avoidance also influences interactions, suggesting that strategies driving the formation of flocks may be complex and context dependent with varying benefits for different actors.

An intelligent approach using support vector machines for monitoring and identification of faults on transmission systems

Power system disturbances are often caused by faults on transmission lines. When faults occur in a power system, the protective relays detect the fault and initiate tripping of appropriate circuit breakers, which isolate the affected part from the rest of the power system. Generally Extra High Voltage (EHV) transmission substations in power systems are connected with multiple transmission lines to neighboring substations. In some cases mal-operation of relays can happen under varying operating conditions, because of inappropriate coordination of relay settings. Due to these actions the power system margins for contingencies are decreasing. Hence, power system protective relaying reliability becomes increasingly important. In this paper an approach is presented using Support Vector Machine (SVM) as an intelligent tool for identifying the faulted line that is emanating from a substation and finding the distance from the substation. Results on 24-bus equivalent EHV system, part of Indian southern grid, are presented for illustration purpose. This approach is particularly important to avoid mal-operation of relays following a disturbance in the neighboring line connected to the same substation and assuring secure operation of the power systems.

Crystal growth, transport and magnetic properties of rare-earth manganite Pr1-xPbxMnO3

Crystal growth, electrical and magnetic properties are reported for mixed valence manganite Pr1-xPbxMnO3 (x = 0.2, 0.23, and 0.3). The crystals with x = 0.2 and 0.23 are ferromagnetic and insulating, whereas that with x = 0.3 is ferromagnetic below 200 K and shows an insulator-metal transition at 235 K. This composition shows a magnetoresistance of 90% in a field of 5 T. In the paramagnetic region, the temperature dependence of magnetic susceptibility of the crystals follows a Curie-Weiss behavior. The thermal evolution of magnetization in the ferromagnetic phase varies as T-3/2, in accordance with Bloch's law. The spin-stiffness constant D obtained from the Bloch constant is found to increase linearly with x. The magnetization does not reach complete saturation upto a field of 5 T. A possible contribution of the Pr spins to the total magnetic moment is discussed.

The Amenability Studies on Beneficiation of Low Grade Phyllite Deposits of Tungsten From Degana, Rajasthan

The phyllite deposit of Degana, Rajasthan, containing tungsten values in the form of wolframite, (Fe, MnWO sub 4 ) finely dispersed in the quartz groundmass, has been quantitatively analysed to give 0.063% WO sub 3 , 6.66% Fe sub 2 O sub 3 , 14.30% Al sub 2 O sub 3 and 67.4% SiO sub 2 . The major gangue minerals identified are quartz, iron oxides and mica along with minor amounts of graphite, fluorite and sulphides. The amenability of the ore to gravity concentration, magnetic separation and a combination of the processes has been studied. A combination of tabling on --100 mesh ground ore and dry magnetic separation of the tabled concentrate gave a final concentrate containing 1.834% WO sub 3 with an overall recovery of only 4.6%. The complex mineralogy combined with fine dispersion of very low W values have contributed to the low recoveries and grades. Graph, photomicrographs. 10 ref.--AA

Hydropower Project Design Incorporating Submergence Costs

Submergence of land is a major impact of large hydropower projects. Such projects are often also dogged by siltation, delays in construction and heavy debt burdens-factors that are not considered in the project planning exercise. A simple constrained optimization model for the benefit~ost analysis of large hydropower projects that considers these features is proposed. The model is then applied to two sites in India. Using the potential productivity of an energy plantation on the submergible land is suggested as a reasonable approach to estimating the opportunity cost of submergence. Optimum project dimensions are calculated for various scenarios. Results indicate that the inclusion of submergence cost may lead to a substanual reduction in net present value and hence in project viability. Parameters such as project lifespan, con$truction time, discount rate and external debt burden are also of significance. The designs proposed by the planners are found to be uneconomic, whIle even the optimal design may not be viable for more typical scenarios. The concept of energy opportunity cost is useful for preliminary screening; some projects may require more detailed calculations. The optimization approach helps identify significant trade-offs between energy generation and land availability.

Measurement of FSH in the ovarian tissue by radioimmunoassay: Correlation to serum FSH levels and follicular development in the hamster

A method is described for monitoring the concentration of endogenous receptor-bound gonadotropin in the ovarian tissue. This involved development of a radioimmunoassay procedure, the validity of which for measuring all of the tissue-bound hormone has been established. The specificity of the method of measurement was indicated by the fact that high levels of FSH could be measured only in target tissue such as follicles, while non-target organs showed little FSH. Using this method, the amount of FSH in the non-luteal ovarian tissue of the hamster at different stages of the estrous cycle was quantitated and compared with serum FSH levels found at these times. No correlation could be found between serum and tissue FSH levels at all times. On the morning of estrus, for example, when the serum level of FSH was high, the ovarian concentration was low, and on the evening of diestrus-2 the ovary exhibited high concentration of FSH, despite the serum FSH concentration being low at this time. The highest concentration of FSH in the ovary during the cycle was found on the evening of proestrus. Although a large amount of this was found in the Graafian follicles, a considerable amount could still be found in the �growing� follicles. Ovarian FSH concentration could be considered to be a reflection of FSH receptor content, since preventing the development of FSH receptors by blocking initiation of follicular development during the cycle resulted in a decrease in the concentration of FSH in the ovary. The high concentration of FSH in the ovary seen on the evening of diestrus-2 was not influenced either by varying the concentration of estrogen or by neutralization of LH. Neutralization of FSH on diestrus-2, on the other hand, caused a drastic reduction in the ovarian LH concentration on the next day (i.e. at proestrus), thus suggesting the importance of FSH in the induction of LH receptors.

Structure of 6-acetoxycoumarin: topochemical photodimerization and analysis of acetoxy...acetoxy interactions in the solid state

C~HaO 4, Mr=204.2, monoclinic, P2Jn,a=3.900(1), =37.530(6), c=6.460(1)A, fl=103.7 (1) °, V= 918.5 (5) A 3, Z = 4, D m = 1.443, D x --- 1.476 Mg m -3, Cu Ks, 2 = 1.5418 ,/k, /t = 0.86 mm -~, F(000) = 424, T= 293 K, R = 0.075 for 1019 significant reflections. Molecules pack in fl-type stacking mode which is characterized by the close packing of parallel and nearly planar reactive double bonds with a separation of 3.900/~ along the a axis.The syn head-head dimer obtained is the direct consequence of this packing arrangement. Molecular packing is stabilized by intermolecular C-H...O hydrogen bonding. Analysis of acetoxy...acetoxy interactions in the acetoxy compounds retrieved from the Cambridge Structural Database reveal that the majority of them are anti-dipolar.

The stereochemistry of a-aminoisobutyric acid containing peptides

a-Aminoisobutyric acid (Aib), * a nonprotein amino acid first described synthetically, I has been found in diverse sources, ranging from peptides of microbial origin2s3 to the Murchison mete~r i te.E~a rly studies of the chemistry of Aib were directed towards the synthesis of model peptides containing this "sterically hindered" amino There have been several reports on the synthesis of Aib containing analogs of biologically active peptides.

Discriminating between natural and anthropogenic aerosol contributions to optical depth over Afro-Asian region

To accurately assess the impact of anthropogenic aerosols on climate, spatial and temporal distribution of its radiative properties is essential. The first step towards separating the radiative impact of natural aerosol from its anthropogenic counterparts is to gather information on natural aerosols. In this paper, we have used data from multiple satellites to derive the anthropogenic aerosol fraction (AAF) over the Afro-Asian region. The AAF was largest during the pre-monsoon season (May-June) and lowest during winter. We have shown that over desert locations the AAF was unexpectedly large (>0.4) and the regionally (and annually) averaged anthropogenic fraction over the Afro-Asian region was 0.54 +/- 0.12. Copyright (C) 2010 Royal Meteorological Society

V-CE Sensing for IGBT Protection in NPC Three Level Converters-Causes For Spurious Trippings and Their Elimination

Neutral point clamped (NPC), three level converters with insulated gate bipolar transistor devices are very popular in medium voltage, high power applications. DC bus short circuit protection is usually done, using the sensed voltage across collector and emitter (i.e., V-CE sensing), of all the devices in a leg. This feature is accommodated with the conventional gate drive circuits used in the two level converters. The similar gate drive circuit, when adopted for NPC three level converter protection, leads to false V-CE fault signals for inner devices of the leg. The paper explains the detailed circuit behavior and reasons, which result in the occurrence of such false V-CE fault signals. This paper also illustrates that such a phenomenon shows dependence on the power factor of the supplied three-phase load. Finally, experimental results are presented to support the analysis. It is shown that the problem can be avoided by blocking out the V-CE sense fault signals of the inner devices of the leg.