Distribution pattern and biomass estimation of benthic invertebrates in Aras reservoir

This study was carried out at monthly basis covering six sampling stations in Aras reservoir in 1995, The samples were collected by Ekman grab with 3 replicates, The results Showed that Oligochaetes were the dominant taxa in this reservoir which were observed all year round and had the highest abundance and biomass, The Chironomidae were the second dominant family. Gammaridae and Mysidae had the least abundance and biomass, Maximum biomass of Oligochaetes was observed in spring with the average figure of 19.03 g/m2 and minimum biomass was observed in winter with average biomass of 5.87 g/m2 Maximum and minimum biomass or Chironomidae were recorded in summer and spring, of which their correspond average biomass were 1.52 and 0.06 g/m2, respectively. The highest and lowest biomass of Mysidae family were observed in summer and spring with the average biomass of 0.46 and 0.00 g/m2, respectively. Gammaridae family observed only in summer. The differences of biomass of these 3 families were significant based on kruskal-wallis nonparametric test (p0.05). Maximum (26.06 g/m2) and minimum biomass (3.14 g/m2) of benthic organisms were observed in stations 4 and 5, respectively and no remarkable variation was observed in the percentage of total organic matter (TOM) content during different seasons. Maximum and minimum average percentage of TOM were 6.66% to 4.79% in spring and winter, respectively. Based on collected data and obtained results, it can be assumed that feeding of fishes, sediment composition, amount of TOM and water temperature were the most important factors effect on temporal and spatial variation in population and biomass of benthic organisms of Aras reservoir

The biomass and distribution of Pseudocumidae in the southern-west coasts of the Caspian Sea (Guilan province)

The most part of the fauna population in the Caspian Sea comprised invertebrates that is dominated by benthic organisms. Cumacea belongs to Arthropoda phylum, class of Crustacea and has an important role as food for sturgeon fishes in the Caspian Sea. This study was performed from autumn 1992 to summer 1993 in sixteen transects and each transect had four stations located at 10,20, 50 and 100 m depths. The survey revealed that the maximum mean biomass of this family was observed at 10 m depth in transect 15 with 9.62 gim2 and the minimum was observed at 20 m depth in transect 1 with 0.07 g/m2. The greatest biomass of this family was observed in spring with average biomass of 6.48 g/m2 and the lowest biomass was observed in autumn-winter with average biomass ofl.47 g/m2. The maximum and minimum mean biomass was observed at 100 m and 10 m depths respectively. The average biomass of this benthos had significant differences in different depths and seasons (P<0.05). The amount of T.O.M had high and considerable changes in different depths with a range of 3.55-10.37% for depths of 10 to 100m, respectively. Also the maximum percentage of sand in sediment was observed in 10m depth with value of 58.64% and minimum value was 34.73% in 100m depth. The mean biomass of this aquatic organism was 4.75 ± o.45 g/m2 in eastren area and 3.59±0.31 g/m2 in western area of this province. Nonparametric statitical analysis of Kruskal- Wallis showed significant diffrence between mean biomass in this two areas (P < 0.05)

Robust Hybrid Linear State Estimator Utilizing SCADA and PMU Measurements

This paper intends to improve the accuracy of power system State Estimation (SE) by introducing a hybrid linear robust state estimator. To this end, automatic bad data rejection is accomplished through an M-estimator, i.e. a Schweppe-type estimator with Huber loss function. The method of Iteratively Reweighted Least Squares (IRLS) is used to maximize the likelihood function in the M-estimator. Leverage measurements are also treated by a simple yet effective formulation. To run the algorithm for real-world large-scale grids, cumbersome construction of the Jacobian matrix at each iteration is avoided. In addition, convergence to the local minima faced in the large-scale Gauss-Newton algorithm is not a concern as the proposed formulation is linear with no approximation. As observability and redundancy considerations mandate SE to take advantage of traditional SCADA measurements along with available PMU measurements, the linearity of the proposed SE formulation is guaranteed regardless of whether PMU-only, SCADA-only or hybrid SCADA/PMU measurements are utilized. In this regard, covariance matrix for measurements weights is derived for both types of measurements. Thanks to the linear formulation and therefore swiftness of the proposed algorithm, SE could be run for different power systems with a few up to thousands of buses

PREPARATION, IDENTIFICATION AND BIOLOGICAL PROPERTIES OF NEW FLUORIDE NANOCOMPOUNDS

Indexación: Web of Science; Scopus.Nanoparticles (NPs) of new fluoride (SrF2 and MgF2) nanocompounds were synthesized by the simple chemical method of precipitation in ethanol. Synthesis of the strontium fluoride (SrF2)-magnesium oxide (MgO) nanocomposite was achieved through the ultrasonic method. These prepared nanopowders were characterized through Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, Powder X-ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM). FT-IR confirmed the purity of the synthesized fluoride NPs by evaluation of the vibrations, and UV-Visible showed the intense absorption peaks of NPs. PXRD analysis indicated the average of particle size, and SEM demonstrated a nearly spherical morphology of the NPs. The antibacterical properties of the nanopowders on Staphylococcus Aureus, Bacillus Subtilis and E. Aklay bacteria were studied, with the strongest effect by the magnesium fluoride (MgF2) NPs and the SrF2-MgO nanocomposite.http://ref.scielo.org/yfr3f

Online Non-iterative Estimation of Transmission Line and Transformer Parameters by SCADA Data

Utilization of various measurements provided by supervisory control and data acquisition (SCADA) system has recently attracted increasing attention. Real-time estimation of transmission line parameters, utilizing voltage and power flow measurements provided by remote terminal units (RTUs) located at line terminals, has been investigated. This paper significantly improves the existing approaches by introducing a novel linear formulation of the problem, which can be solved in a closed form. The distributed-parameter model of long transmission lines is considered and its parameters are estimated in a noniterative manner using traditional SCADA measurements. The new method is further extended to estimate transformer series impedance and tap position using SCADA measurements, linearly. As such, the shortcomings associated with the previously proposed iterative approach, e.g. concern over convergence, for transmission line parameters are avoided. Moreover, the novel technique for estimating transformer parameters allows to determine the tap position as well as updated transformer series impedance. Furthermore, a thorough analysis is presented to take the measurement accuracy into account. Simulation results for different transmission lines and transformers in the IEEE 118-bus test system are reported. The results obtained indicate successful performance of the proposed algorithms