Properties of water masses, taxa abundance, and isotopic ratios of samples obtained around Svalbard archipelago

The feeding strategies of Calanus hyperboreus, C. glacialis, and C. finmarchicus were investigated in the high-Arctic Svalbard region (77-81 °N) in May, August, and December, including seasons with algal blooms, late- to post-bloom situations, and unproductive winter periods. Stable isotope and fatty acid trophic marker (FATM) techniques were employed together to assess trophic level (TL), carbon sources (phytoplankton vs. ice algae), and diet of the three Calanus species. In addition, population development, distribution, and nutritional state (i.e. storage lipids) were examined to estimate their population status at the time of sampling. In May and August, the vertical distribution of the three Calanus species usually coincided with the maximum algal biomass. Their stable isotope and fatty acid (FA) composition indicated that they all were essentially herbivores in May, when the algal biomass was highest. Their FA composition, however, revealed different food preferences. C. hyperboreus had high proportions of 18:4n3, suggesting that it fed mainly on Phaeocystis, whereas C. glacialis and C. finmarchicus had high proportions of 16:4n1, 16:1n7, and 20:5n3, suggesting diatoms as their major food source. Carbon sources (i.e. phytoplankton vs. ice algae) were not possible to determine solely from FATM techniques since ice-diatoms and pelagic-diatoms were characterised by the same FA. However, the enriched d13C values of C. glacialis and C. finmarchicus in May indicated that they fed both on pelagic- and ice-diatoms. Patterns in absolute FA and fatty alcohol composition revealed that diatoms were the most important food for C. hyperboreus and C. glacialis, followed by Phaeocystis, whereas diatoms, Phaeocystis and other small autotrophic flagellates were equally important food for C. finmarchicus. During periods of lower algal biomass, only C. glacialis exhibited evidence of significant dietary switch, with a TL indicative of omnivory (mean TL=2.4). Large spatial variability was observed in population development, distribution, and lipid store sizes in August. At the northernmost station at the southern margin of the Arctic Ocean, the three Calanus species had similarly low lipid stores as they had in May, suggesting that they ascended later in the year. In December, relatively lipid-rich specimens had TL similar to those during the peak productive season (TL~2.0), suggesting that they were hibernating and not feeding on the available refractory material available at that time of the year. In contrast, lipid-poor specimens in December had substantially high TL (TL=2.5), suggesting that they were active and possibly were feeding.

(Table 3) Observations of Mediterranean water lenses in the Eastern North Atlantic

Spreading pattern and mesoscale structure of Mediterranean water outflow in the eastern North Atlantic are studied on the basis of historical hydrographical records. Effect of bottom topography on Mediterranean water distribution is revealed. It is shown that the Mediterranean water outflow is divided into two streams after leaving the Gulf of Cadiz. These are northwestern and southwestern ones; the former is more intensive and spreads in more regular and continuous way. West of the Tejo (Tagus) Plateau it splits into three branches; the most intense of them keeps continuity up to 14°W. The less intensive southwestern stream passes south of the Gettysburg Bank and splits into two branches immediately after the Gulf of Cadiz. From 11°W, this stream has lenticular, intermittent character. West of 14°-15°W all Mediterranean water branches are represented mainly by isolated salty patches. As a result of historical data analysis in the 32°-44°N, 8°-22°W area, 30 Mediterranean water lenses have been found; 12 of them had not been previously mentioned in publications. A table of main parameters of Mediterranean water lenses is presented. It includes data of 108 observations from 1911 to 1993.

New selective earth faults only current directional method for isolated neutral systems

In order to achieve total selectivity at electrical distribution networks it is of great importance to analyze the defect currents at ungrounded power systems. This information will help to grant selectivity at electrical distribution networks ensuring that only the defect line or feeder is removed from service. In the present work a new selective and directional protection method for ungrounded power systems is evaluated. The new method measures only defect currents to detect earth faults and works with a directional criterion to determine the line under faulty conditions. The main contribution of this new technique is that it can detect earth faults in outgoing lines at any type of substation avoiding the possible mismatch of traditional directional earth fault relays. This detection technique is based on the comparison of the direction of a reference current to the direction of all earth fault capacitive currents at all the feeders connected to the same bus bars. This new method has been validated through computer simulations. The results for the different cases studied are remarkable, proving total validity and usefulness of the new method.

Probabilistic analysis of water availability for agriculture and associated crop net margins.

Rising water demands are difficult to meet in many regions of the world. In consequence, under meteorological adverse conditions, big economic losses in agriculture can take place. This paper aims to analyze the variability of water shortage in an irrigation district and the effect on farmer?s income. A probabilistic analysis of water availability for agriculture in the irrigation district is performed, through a supply-system simulation approach, considering stochastically generated series of stream-flows. Net margins associated to crop production are as well estimated depending on final water allocations. Net margins are calculated considering either single-crop farming, either a polyculture system. In a polyculture system, crop distribution and water redistribution are calculated through an optimization approach using the General Algebraic Modeling System (GAMS) for several scenarios of irrigation water availability. Expected net margins are obtained by crop and for the optimal crop and water distribution. The maximum expected margins are obtained for the optimal crop combination, followed by the alfalfa monoculture, maize, rice, wheat and finally barley. Water is distributed as follows, from biggest to smallest allocation: rice, alfalfa, maize, wheat and barley.

Distribution, control, and measurement of irrigation water on the farm /

"Issued July 1963."

Appraisal of the water resources of the eastern part of the Tulare aquifer, Beadle, Hand, and Spink Counties, South Dakota /

Mode of access: Internet.

An assessment of the performance of high density polyethylene copolymers for natural gas distribution pipes

The total thermoplastics pipe market in west Europe is estimated at 900,000 metric tonnes for 1977 and is projected to grow to some 1.3 million tonnes of predominantly PVC and polyolefins pipe by 1985. By that time, polyethylene for gas distribution pipe and fittings will represent some 30% of the total polyethylene pipe market. The performance characteristics of a high density polyethylene are significantly influenced by both molecular weight and type of comonomer; the major influences being in the long-term hoop stress resistance and the environmental stress cracking resistance. Minor amounts of hexene-1 are more effective than comonomers lower in the homologous series, although there is some sacrifice of density related properties. A synergistic improvement is obtained by combining molecular weight increase with copolymerisation. The Long-term design strength of polyethylene copolymers can be determined from hoop stress measurement at elevated temperatures and by means of a separation factor of approximate value 22, extrapolation can be made to room temperature performance for a water environment. A polyethylene of black composition has a sufficiently improved performance over yellow pigmented pipe to cast doubts on the validity of internationally specifying yellow coded pipe for gas distribution service. The chemical environment (condensate formation) that can exist in natural gas distribution networks has a deleterious effect on the pipe performance the reduction amounting to at least two decades in log time. Desorption of such condensate is very slow and the influence of the more aggressive aromatic components is to lead to premature stress cracking. For natural gas distribution purposes, the design stress rating should be 39 Kg/cm2 for polyethylenes in the molecular weight range of 150 - 200,000 and 55 Kg/cm2 for higher molecular weight materials.

Assessing the resilience of water supply systems in Oman

Water systems in the Sultanate of Oman are inevitably exposed to varied threats and hazards due to both natural and man-made hazards. Natural disasters, especially tropical cyclone Gonu in 2007, cause immense damage to water supply systems in Oman. At the same time water loss from leaks is a major operational problem. This research developed an integrated approach to identify and rank the risks to the water sources, transmission pipelines and distribution networks in Oman and suggests appropriate mitigation measures. The system resilience was evaluated and an emergency response plan for the water supplies developed. The methodology involved mining the data held by the water supply utility for risk and resilience determination and operational data to support calculations of non-revenue water. Risk factors were identified, ranked and scored at a stakeholder workshop and the operational information required was principally gathered from interviews. Finally, an emergency response plan was developed by evaluating the risk and resilience factors. The risk analysis and assessment used a Coarse Risk Analysis (CRA) approach and risk scores were generated using a simple risk matrix based on WHO recommendations. The likelihoods and consequences of a wide range of hazardous events were identified through a key workshop and subsequent questionnaires. The thesis proposes a method of translating the detailed risk evaluations into resilience scores through a methodology used in transportation networks. A water audit indicated that the percentage of NRW in Oman is greater than 35% which is similar to other Gulf countries but high internationally. The principal strategy for managing NRW used in the research was the AWWA water audit method which includes free to use software and was found to be easy to apply in Oman. The research showed that risks to the main desalination processes can be controlled but the risk due to feed water quality might remain high even after implementing mitigation measures because the intake is close to an oil port with a significant risk of oil contamination and algal blooms. The most severe risks to transmission mains were found to be associated with pipe rather than pump failure. The systems in Oman were found to be moderately resilient, the resilience of desalination plants reasonably high but the transmission mains and pumping stations are very vulnerable. The integrated strategy developed in this study has a wide applicability, particularly in the Gulf area, which may have risks from exceptional events and will be experiencing NRW. Other developing countries may also experience such risks but with different magnitudes and the risk evaluation tables could provide a useful format for further work.

Age distribution of the central stars of galactic disk planetary nebulae

Context. Determination of the ages of central stars of planetary nebulae (CSPN) is a complex problem, and there is presently no single method that can be generally applied. We have developed several methods of estimating the ages of CSPN, based on both the observed nebular properties and some properties of the stars themselves. Aims. Our aim is to estimate the ages and the age distribution of CSPN and to compare the derived results with mass and age determinations of CSPN and white dwarfs based on empirical determinations of these quantities. Methods. We considered a sample of planetary nebulae in the galactic disk, most of which (similar to 69%) are located in the solar neighbourhood, within 3 kpc from the Sun. We discuss several methods of deriving the age distribution of CSPN, namely; (i) the use of an age-metallicity relation that also depends on the galactocentric distance; (ii) the use of an age-metallicity relation obtained for the galactic disk; and (iii) the determination of ages from the central star masses obtained from the observed nitrogen abundances. Results. We estimated the age distribution of CSPN with average uncertainties of 1-2 Gyr, and compared our results with the expected distribution based both on the observed mass distribution of white dwarfs and on the age distribution derived from available mass distributions of CSPN. Based on our derived age distributions, we conclude that most CSPN in the galactic disk have ages under 6 Gyr, and that the age distribution is peaked around 2-4 Gyr.

Real-Time Voltage Regulation in Power Distribution System Using Fuzzy Control

Two different fuzzy approaches to voltage control in electric power distribution systems are introduced in this paper. The real-time controller in each case would act on power transformers equipped with under-load tap changers. Learning systems are employed to turn the voltage-control relays into adaptive devices. The scope of this study has been limited to the power distribution substation, and the voltage measurements and control actions are carried out on the secondary bus. The capacity of fuzzy systems to handle approximate data, together with their unique ability to interpret qualitative information, make it possible to design voltage-control strategies that satisfy the requirements of the Brazilian regulatory bodies and the real concerns of the electric power distribution companies. Fuzzy control systems based on these two strategies have been implemented and the test results were highly satisfactory.

Fuzzy Control System for Voltage Regulation In Power Transformers

A fuzzy control strategy for voltage regulation in electric power distribution systems is introduced in this article. This real-time controller would act on power transformers equipped with under-load tap changers. The fuzzy system was employed to turn the voltage-control relays into adaptive devices. The scope of the present study has been limited to the power distribution substation, and both the voltage measurements and control actions are carried out on the secondary bus. The capacity of fuzzy systems to handle approximate data, together with their unique ability to interpret qualitative information, make it possible to design voltage control strategies that satisfy both the requirements of the Brazilian regulatory bodies and the real concerns of the electric power distribution companies. A prototype based on the fuzzy control strategy proposed in this paper has also been implemented for validation purposes and its experimental results were highly satisfactory.

A New Approach for Video Adaptation through Overlay Services Networks

Video adaptation is an extensively explored content providing technique aimed at appropriately suiting several usage scenarios featured by different network requirements and constraints, user`s terminal and preferences. However, its usage in high-demand video distribution systems, such as CNDs, has been badly approached, ignoring several aspects of optimization of network use. To address such deficiencies, this paper presents an approach for implementing the adaptation service by exploring the concept of overlay services networks. As a result of demonstrate the benefits of this proposal, it is made a comparison of this proposed adaptation service with other strategies of video adaptation.

Modeling and measuring double-frequency jitter in one-way master-slave networks

The double-frequency jitter is one of the main problems in clock distribution networks. In previous works, sonic analytical and numerical aspects of this phenomenon were studied and results were obtained for one-way master-slave (OWMS) architectures. Here, an experimental apparatus is implemented, allowing to measure the power of the double-frequency signal and to confirm the theoretical conjectures. (C) 2008 Elsevier B.V. All rights reserved.

Distribution and storage characterization of soil solution for drip irrigation

The increased use of marginal quality water with drip irrigation requires sound fertigation practices that reconcile environmental concerns with viable crop production objectives. We conducted experiments to characterize dynamics and patterns of soil solution within wet bulb formed by drip irrigation. Time-domain reflectometry probes were used to monitor the distribution of potassium nitrate (KNO(3)) and water distribution from drippers discharging at constant flow rates of 2, 4 and 8 L h(-1) in soil-filled containers. Considering results from different profiles, we observed greater solute storage near the dripper decreasing gradually towards the wetting front. About half of the applied KNO(3) solution (48%) was stored in the first layer (0-0.10 m) for all experiments, 29% was stored in the next layer (0.10-0.20 m). Comparing different dripper flow rates, we observed higher solution storage for 4 L h(-1), with 45, 53 and 47% of applied KNO(3) solution accumulating in the first layer (0-0.10 m) for dripper flow rates of 2, 4 and 8 L h(-1), respectively. The results suggest that based on the volume and frequency used in this experiment, it would be advantageous to apply small amounts of solution at more frequent intervals to reduce deep percolation losses of applied water and solutes.

The large-scale distribution of neutral hydrogen in the Fornax region

Using data from the H I Parkes All Sky Survey (HIPASS), we have searched for neutral hydrogen in galaxies in a region similar to25x25 deg(2) centred on NGC 1399, the nominal centre of the Fornax cluster. Within a velocity search range of 300-3700 km s(-1) and to a 3sigma lower flux limit of similar to40 mJy, 110 galaxies with H I emission were detected, one of which is previously uncatalogued. None of the detections has early-type morphology. Previously unknown velocities for 14 galaxies have been determined, with a further four velocity measurements being significantly dissimilar to published values. Identification of an optical counterpart is relatively unambiguous for more than similar to90 per cent of our H I galaxies. The galaxies appear to be embedded in a sheet at the cluster velocity which extends for more than 30degrees across the search area. At the nominal cluster distance of similar to20 Mpc, this corresponds to an elongated structure more than 10 Mpc in extent. A velocity gradient across the structure is detected, with radial velocities increasing by similar to500 km s(-1) from south-east to north-west. The clustering of galaxies evident in optical surveys is only weakly suggested in the spatial distribution of our H I detections. Of 62 H I detections within a 10degrees projected radius of the cluster centre, only two are within the core region (projected radius