Nickel chloride: potential accumulation from the airway. Toxicokinetics in rats.

The rate removal of nickel from the airway was measured in vivo. Removal in vivo was studied by intratracheal injection of nickel chloride solutions. Regardless of time after injection, the lungs and heart retained the greatest concentration of nickel and 40 days after 1.68 mumol administration they were the organs where nickel was still significantly measurable. The slow removal of nickel may indicate the presence of high affinity binding sites in the lung. Nickel can interact with others metals, such as copper and zinc, so that nickel exposure may have public health implications.

Mapping Wigner distribution functions into semiclassical distribution functions

A mapping that relates the Wigner phase-space distribution function of a given stationary quantum mechani-cal wave function, a solution of the Schrödinger equation, to a specific solution of the Liouville equation, both subject to the same potential, is studied. By making this mapping, bound states are described by semiclassical distribution functions still depending on Planck's constant, whereas for elastic scattering of a particle by a potential they do not depend on it, the classical limit being reached in this case. Following this method, the mapped distributions of a particle bound in the Pöschl-Teller potential and also in a modified oscillator potential are obtained.

Growth parameters and nutrient content in four multipurpose tree species with potential characteristics for agroforestry systems in a Cerrado region in Botucatu, São Paulo State, Brazil

In order to evaluate growth characteristics, adaptability, biomass production, nutrient recycling, nutrient distribution and the ability to regenerate degraded land, a trial using four multipurpose tree species (Leucaena leucocephala, Leucaena diversifolia, Acacia melanoxylon and Mimosa scabrella) was undertaken over two years in a distrophic red yellow latosol (oxisol) following a randomized block experimental design with four replications. At the age of two years, A. melanoxylon and L. diversifolia were the tallest species (5.25 and 4.97 m, respectively) and A. melanoxylon and M. scabrella had the largest diameters at 20 cm from tree base. Mimosa scabrella and A. melanoxylon had the highest dry matter production and quantity of nutrients in the above ground biomass. In all species, the highest nutrient contents were found in the leaves, followed by branches and stems. From all species, the highest Nutrient Utilization Efficiency Indexes were obtained for sulphur, phosphorous, and magnesium; L. diversifolia was the most efficient for nitrogen, potassium, calcium, sulphur, and manganese, while A. melanoxylon was the most efficient for phosphorus, magnesium, boron, iron, and zinc. Litter production levels over a three month period were as follows: M. scabrella > A. melanoxylon > L. diversifolia > L. leucocephala. Litter nutrient content was higher in M. scabrella than in the other species.

Yield and fruit size distribution of processing tomato cultivars

The productivity and fruit size distribution of 28 processing tomato cultivars were analyzed to determine the ones with potential for fresh market. The experiment was done in Jaboticabal-SP, Brazil (21o15'22'' South, 48o18'58'' West, altitude 595 m), in a Haplorthox soil, from June to December. The cultivars H 7155, Hypeel 108, Andino, U 573, H 9036, Ipa 6, H 9494, AG 33, Yuba, RPT 1294, AG 72, Peelmech, Curicó, Hypeel 45, RPT 1478, H 9492, H 9498, H 2710, Hitech 45, Halley, Botu 13, H 9553, U 646, NK 1570, AG 45, RPT 1095, RPT 1570 and PSX 37511 were evaluated. The experimental design was randomized blocks, with four repetitions, and five plants per experimental unit. Fruits harvested from each experimental unit were counted, classified by transversal diameter (large, medium, small, very small and cull) and then weighed. Cultivars AG 72, H 9498, Hypeel 45, RPT 1095 and Curicó yielded more than 70 fruits per plant, on average. The total production per plant of cultivars AG 72, H 9498, Hypeel 45, H 7155, Hypeel 108, Halley, Hitech, RPT 1095, H 9494, H 9036 and Curicó was greater than 4 kg. Considering the weight of large and medium fruits, categories which are important for fresh market, the cultivars H 2710, Botu 13, U 573, Hypeel 45, Yuba, RPT 1294 and Ipa 6 presented values above 50% for production.

PMUs optimized allocation using a tabu search algorithm for fault location in electric power distribution system

Phasor Measurement Units (PMUs) optimized allocation allows control, monitoring and accurate operation of electric power distribution systems, improving reliability and service quality. Good quality and considerable results are obtained for transmission systems using fault location techniques based on voltage measurements. Based on these techniques and performing PMUs optimized allocation it is possible to develop an electric power distribution system fault locator, which provides accurate results. The PMUs allocation problem presents combinatorial features related to devices number that can be allocated, and also probably places for allocation. Tabu search algorithm is the proposed technique to carry out PMUs allocation. This technique applied in a 141 buses real-life distribution urban feeder improved significantly the fault location results. © 2004 IEEE.

Distribution line models analysis for loss calculation within three-phase three-wire power flow algorithms

Three-phase three-wire power flow algorithms, as any tool for power systems analysis, require reliable impedances and models in order to obtain accurate results. Kron's reduction procedure, which embeds neutral wire influence into phase wires, has shown good results when three-phase three-wire power flow algorithms based on current summation method were used. However, Kron's reduction can harm reliabilities of some algorithms whose iterative processes need loss calculation (power summation method). In this work, three three-phase three-wire power flow algorithms based on power summation method, will be compared with a three-phase four-wire approach based on backward-forward technique and current summation. Two four-wire unbalanced medium-voltage distribution networks will be analyzed and results will be presented and discussed. © 2004 IEEE.

Investigating effects of neutral wire and grounding in distribution systems with faults

In some applications like fault analysis, fault location, power quality studies, safety analysis, loss analysis, etc., knowing the neutral wire and ground currents and voltages could be of particular interest. In order to investigate effects of neutrals and system grounding on the operation of the distribution feeders with faults, in this research a hybrid short circuit algorithm is generalized. In this novel use of the technique, the neutral wire and assumed ground conductor are explicitly represented. Results obtained from several case studies using IEEE 34-node test network are presented and discussed.

Planning of secondary distribution circuits through evolutionary algorithms

In this work, the planning of secondary distribution circuits is approached as a mixed integer nonlinear programming problem (MINLP). In order to solve this problem, a dedicated evolutionary algorithm (EA) is proposed. This algorithm uses a codification scheme, genetic operators, and control parameters, projected and managed to consider the specific characteristics of the secondary network planning. The codification scheme maps the possible solutions that satisfy the requirements in order to obtain an effective and low-cost projected system-the conductors' adequate dimensioning, load balancing among phases, and the transformer placed at the center of the secondary system loads. An effective algorithm for three-phase power flow is used as an auxiliary methodology of the EA for the calculation of the fitness function proposed for solutions of each topology. Results for two secondary distribution circuits are presented, whereas one presents radial topology and the other a weakly meshed topology. © 2005 IEEE.

Evaluation of a multiobjective performance index for distribution systems with distributed generation

Here a multiobjective performance index for distribution systems with distributed generation based on a steady-state analysis of the network is proposed. This index quantifies the distributed generation impact on total losses, voltage profile and short circuit currents, and will be used as objective function in an evolutionary algorithm aimed at searching the best points for connecting distributed generators. Moreover, a loss allocation technique, based on the Zbus method, is applied on the original configuration of the network to obtain a good quality initial population. An IEEE medium voltage distribution network is analysed and results are presented and discussed.

Voltage regulator modeling for the three-phase power flow in distribution networks

In this paper a three-phase power flow for electrical distribution systems considering different models of voltage regulators is presented. A voltage regulator (VR) is an equipment that maintains the voltage level in a predefined value in a distribution line in spite of the load variations within its nominal power. Three different types of connections are analyzed: 1) wye-connected regulators, 2) open delta-connected regulators and 3) closed delta-connected regulators. To calculate the power flow, the three-phase backward/forward sweep algorithm is used. The methodology is tested on the IEEE 34 bus distribution system. ©2008 IEEE.

Potential use of the veris apparent EC sensor to predict soil texture under the semi-arid conditions of central Arizona

The operational details of the apparent electrical conductivity (ECa) sensor manufactured by Veris Technologies have been extensively documented in literature reports, but the geographical distribution of these research studies indicate a strong regional concentration in the US Mid-west and Southern states. The agricultural lands of these states diverge significantly to the soil conditions and water regime of irrigated land in the US South-western states such as Arizona where there is no previous research reports of the use of this particular sensor. The objectives of the present study were to analyze the performance of this sensor under the conditions of typical soils in irrigated farms of Central Arizona. We tested under static conditions the performance of the sensor on three soils of contrasting texture. Observations were collected as time series data as soil moisture changed from saturation to permanent wilting point. Observations were repeated at the hours of lowest and highest temperatures. In addition, this study included soil penetration resistance and salinity determinations. Preliminary results indicate that soil temperature of the upper layer caused the most dynamic change in the sensor output. The ECa curves of the three soil textures tested had well defined distinctive characteristics. Final multivariate analysis is pending.

Fault section estimation in automated distribution substations

In this paper, a methodology based on Unconstrained Binary Programming (UBP) model and Genetic Algorithms (GAs) is proposed for estimating fault sections in automated distribution substations. The UBP model, established by using the parsimonious set covering theory, looks for the match between the relays' protective alarms informed by the SCADA system and their expected states. The GA is developed to minimize the UBP model and estimate the fault sections in a swift and reliable manner. The proposed methodology is tested by utilizing a real-life automated distribution substation. Control parameters of the GA are tuned to achieve maximum computational efficiency and reduction of processing time. Results show the potential and efficiency of the methodology for estimating fault section in real-time at Distribution Control Centers. ©2009 IEEE.

An efficient codification to solve distribution network reconfiguration for loss reduction problem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Energy efficiency potential in Jamaica: challenges, opportunities and strategies for implementation

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Trade and sustainable development: spatial distribution of trade policies impacts on agriculture

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